The document describes observations from the Voyager 2 spacecraft of plasma properties at and near the heliopause (HP), which separates the solar wind from the very local interstellar medium (VLISM). Key findings include:
1) Voyager 2 observed a plasma boundary region starting 1.5 au before the HP, where the plasma slowed down, heated up, and doubled in density compared to typical heliosheath plasma.
2) Just inside the HP, a thinner boundary layer was observed over 0.06 au where the radial speed decreased and density and magnetic field increased.
3) In the VLISM beyond the HP, plasma currents were variable and implied temperatures of 30,000-50
This document discusses fluid-induced vibration (FIV) in heat exchangers. It covers topics like vortex shedding, synchronization, critical velocity, fluid-elastic instability, and vibration damage patterns. The key points are:
- Vortex shedding from cylindrical structures can cause fluid excitation forces at the shedding frequency, and fluid-structure coupling forces if that frequency matches structural natural frequencies.
- There is a critical cross-flow velocity at which fluid-elastic instability occurs, causing rapid increases in vibration amplitude.
- Vibration damage in heat exchangers can include tube collisions, baffle damage, tube sheet effects, and acoustic resonance failures.
This document summarizes research on generating micron- and nanosize liquid droplets using surface acoustic waves (SAWs). SAWs produce localized acoustic and electric Maxwell pressures near the contact line between a liquid drop and solid substrate. These pressures generate two sequences of self-similar hemispherical satellite droplets at different scales. The acoustic pressure dominates when the film thickness exceeds one-quarter the SAW wavelength and affects the mother drop shape and stability. The Maxwell pressure of nanodrops exceeds ten atmospheres and is sensitive to contact angle. Scaling theories are presented to explain how acoustic and Maxwell pressures govern droplet sizes.
This document describes an experiment to study the effects of buoyancy and momentum on thermal plumes. Warm dyed water was pumped into a tank of cooler water at two different flow rates, creating thermal plumes. A thermocouple array measured temperature profiles in the plumes, which were used to calculate reduced gravities, buoyancy fluxes, and momentum fluxes. The Morton length scale was determined for each flow rate, showing one plume was momentum-dominated and one was buoyancy-dominated. Temperature profiles, normalized reduced buoyancy plots, and centerline reduced buoyancy plots were analyzed to characterize the thermal structure and test scaling laws of the plumes.
This document discusses open channel flow equations and concepts. It introduces the continuity equation, energy equation, and Manning's equation for calculating velocity in uniform open channel flow. It provides sample calculations using Manning's equation and discusses computing a weighted Manning's coefficient for channels with varying roughness.
This study examines the effect of rain on ASCAT observations of sea surface radar cross-section using simultaneous rain measurements from NEXRAD radars. Three rain events were analyzed over Gulf of Mexico in 2008-2009. Results show rain can cause substantial increases in backscatter, from 2-4 dB depending on incidence angle, leading to errors in estimated wind speed of around 60%. The change in backscatter was found to depend on incidence angle but consequences were similar across angles due to wind speed models. Substantial wind errors were identified for rain rates of 6-20 mm/hr. Extra care is needed when using ASCAT data in tropical rainy regions.
This document presents a unified scaling law for earthquakes proposed by the authors. The scaling law links together established patterns in earthquake occurrence, including the Gutenberg-Richter law relating magnitude to frequency, the Omori law describing the decay of aftershock rates over time, and the fractal nature of fault systems. The authors analyze earthquake catalog data from southern California from 1984-2000 to test the scaling law. They find the intervals between earthquakes above varying magnitude cutoffs follow a scaling law that spans eight orders of magnitude, indicating earthquakes are part of a hierarchical, correlated clustering phenomenon with no clear distinction between main shocks and aftershocks. This supports the hypothesis that earthquakes are a self-organized critical phenomenon.
Chapter 3 linear wave theory and wave propagationMohsin Siddique
Small amplitude wave theory provides a mathematical description of periodic progressive waves using linear assumptions. It assumes wave amplitude is small compared to wavelength and depth. The key equations derived are the wave dispersion relationship and expressions for water particle velocity, acceleration, and pressure as functions of depth and phase. Wave energy is calculated as the sum of kinetic and potential energy. Wave power is the rate at which wave energy is transmitted shoreward and varies with depth from 0.5 in deep water to 1.0 in shallow water. Wave characteristics like height, length, and celerity change as waves propagate into shallower depths based on conservation of energy.
This document summarizes direct numerical simulations (DNS) of multiphase flows performed by Grétar Tryggvason and colleagues. It discusses DNS of bubbly flows in vertical channels, including the effects of bubble deformability and size on turbulent upflow. Machine learning methods are applied to DNS data to derive closure relationships for modeling averaged multiphase flows. More complex gas-liquid flows involving many bubbles of different sizes in turbulent channel flow are also examined.
This document discusses fluid-induced vibration (FIV) in heat exchangers. It covers topics like vortex shedding, synchronization, critical velocity, fluid-elastic instability, and vibration damage patterns. The key points are:
- Vortex shedding from cylindrical structures can cause fluid excitation forces at the shedding frequency, and fluid-structure coupling forces if that frequency matches structural natural frequencies.
- There is a critical cross-flow velocity at which fluid-elastic instability occurs, causing rapid increases in vibration amplitude.
- Vibration damage in heat exchangers can include tube collisions, baffle damage, tube sheet effects, and acoustic resonance failures.
This document summarizes research on generating micron- and nanosize liquid droplets using surface acoustic waves (SAWs). SAWs produce localized acoustic and electric Maxwell pressures near the contact line between a liquid drop and solid substrate. These pressures generate two sequences of self-similar hemispherical satellite droplets at different scales. The acoustic pressure dominates when the film thickness exceeds one-quarter the SAW wavelength and affects the mother drop shape and stability. The Maxwell pressure of nanodrops exceeds ten atmospheres and is sensitive to contact angle. Scaling theories are presented to explain how acoustic and Maxwell pressures govern droplet sizes.
This document describes an experiment to study the effects of buoyancy and momentum on thermal plumes. Warm dyed water was pumped into a tank of cooler water at two different flow rates, creating thermal plumes. A thermocouple array measured temperature profiles in the plumes, which were used to calculate reduced gravities, buoyancy fluxes, and momentum fluxes. The Morton length scale was determined for each flow rate, showing one plume was momentum-dominated and one was buoyancy-dominated. Temperature profiles, normalized reduced buoyancy plots, and centerline reduced buoyancy plots were analyzed to characterize the thermal structure and test scaling laws of the plumes.
This document discusses open channel flow equations and concepts. It introduces the continuity equation, energy equation, and Manning's equation for calculating velocity in uniform open channel flow. It provides sample calculations using Manning's equation and discusses computing a weighted Manning's coefficient for channels with varying roughness.
This study examines the effect of rain on ASCAT observations of sea surface radar cross-section using simultaneous rain measurements from NEXRAD radars. Three rain events were analyzed over Gulf of Mexico in 2008-2009. Results show rain can cause substantial increases in backscatter, from 2-4 dB depending on incidence angle, leading to errors in estimated wind speed of around 60%. The change in backscatter was found to depend on incidence angle but consequences were similar across angles due to wind speed models. Substantial wind errors were identified for rain rates of 6-20 mm/hr. Extra care is needed when using ASCAT data in tropical rainy regions.
This document presents a unified scaling law for earthquakes proposed by the authors. The scaling law links together established patterns in earthquake occurrence, including the Gutenberg-Richter law relating magnitude to frequency, the Omori law describing the decay of aftershock rates over time, and the fractal nature of fault systems. The authors analyze earthquake catalog data from southern California from 1984-2000 to test the scaling law. They find the intervals between earthquakes above varying magnitude cutoffs follow a scaling law that spans eight orders of magnitude, indicating earthquakes are part of a hierarchical, correlated clustering phenomenon with no clear distinction between main shocks and aftershocks. This supports the hypothesis that earthquakes are a self-organized critical phenomenon.
Chapter 3 linear wave theory and wave propagationMohsin Siddique
Small amplitude wave theory provides a mathematical description of periodic progressive waves using linear assumptions. It assumes wave amplitude is small compared to wavelength and depth. The key equations derived are the wave dispersion relationship and expressions for water particle velocity, acceleration, and pressure as functions of depth and phase. Wave energy is calculated as the sum of kinetic and potential energy. Wave power is the rate at which wave energy is transmitted shoreward and varies with depth from 0.5 in deep water to 1.0 in shallow water. Wave characteristics like height, length, and celerity change as waves propagate into shallower depths based on conservation of energy.
This document summarizes direct numerical simulations (DNS) of multiphase flows performed by Grétar Tryggvason and colleagues. It discusses DNS of bubbly flows in vertical channels, including the effects of bubble deformability and size on turbulent upflow. Machine learning methods are applied to DNS data to derive closure relationships for modeling averaged multiphase flows. More complex gas-liquid flows involving many bubbles of different sizes in turbulent channel flow are also examined.
Physical significance of non dimensional numbersvaibhav tailor
This document discusses four non-dimensional numbers that are used in heat transfer analysis:
The Nusselt number relates convective heat transfer to conductive heat transfer through a characteristic length and thermal conductivity. The Grashof number compares buoyancy and inertia forces to viscous forces in natural convection. The Prandtl number is the ratio of momentum diffusivity to thermal diffusivity, relating how a fluid conducts momentum and heat. The Reynolds number compares inertial to viscous forces, indicating flow regime from laminar to turbulent. These non-dimensional numbers provide insight into dominant transfer mechanisms in heat transfer problems.
1. Heat transfer occurs through three methods: conduction, convection, and radiation.
2. Conduction involves the transfer of heat through direct contact of particles. Convection involves the transfer of heat by fluid motion. Radiation involves heat transfer through electromagnetic waves without a medium.
3. Heat transfer is important across several engineering disciplines for applications like cooling systems, fluid heating/cooling, building design, and engines.
The document provides an overview of wind energy and wind turbine technology. It outlines the objectives to understand wind measurement and analysis, the workings of wind turbines and their components. The key sources and characteristics of wind are described, including types of wind patterns and how wind speed varies with location, time and height. Methods for measuring and analyzing wind resources at potential wind farm sites are also summarized.
Reconfinement and loss of stability in jets from active galactic nucleiSérgio Sacani
ets powered by active galactic nuclei appear impressively stable compared with their terrestrial and laboratory coun-terparts—they can be traced from their origin to distances exceeding their injection radius by up to a billion times1,2. However, some less energetic jets get disrupted and lose their coherence on the scale of their host galaxy1,3. Quite remark-ably, on the same scale, these jets are expected to become confined by the thermal pressure of the intra-galactic gas2. Motivated by these observations, we have started a system-atic study of active galactic nuclei jets undergoing reconfine-ment via computer simulations. Here, we show that in the case of unmagnetized relativistic jets, the reconfinement is accom-panied by the development of an instability and transition to a turbulent state. During their initial growth, the perturba-tions have a highly organized streamwise-oriented structure, indicating that it is not the Kelvin–Helmholtz instability, the instability which has been the main focus of the jet stability studies so far4,5. Instead, it is closely related to the centrifugal instability6. This instability is likely to be behind the division of active galactic nuclei jets into two morphological types in the Fanaroff–Riley classification7.
In this study the kinematic wave equation has been solved numerically using the modified Lax
explicit finite difference scheme (MLEFDS) and used for flood routing in a wide prismatic channel and a nonprismatic
channel. Two flood waves, one sinusoidal wave and one exponential wave, have been imposed at the
upstream boundary of the channel in which the flow is initially uniform. Six different schemes have been
introduced and used to compute the routing parameter, the wave celerity c. Two of these schemes are based on
constant depth and use constant celerity throughout the computation process. The rest of the schemes are based
on local depths and give celerity dependent on time and space. The effects of the routing parameter c on the
travel time of flood wave, the subsidence of the flood peak and the conservation flood flow volume have been
studied. The results seem to indicate that there is a minimal loss/gain of flow volume whatever the scheme is.
While it is confirmed that neither of the schemes is 100% volume conservative, it is found that the scheme
Kinematic Wave Model-2 (KWM-II) gives the most accurate result giving only 0.1% error in perspective of
volume conservation. The results obtained in this study are in good qualitative agreement with those obtained in
other similar studies.
The document summarizes wave generation studies conducted in a 3D wave basin. Periodic waves were generated using sinusoidal paddle motions to study propagation properties at different locations. Two second-order wave components were identified through Fourier analysis: bounded waves propagating at the same speed as first-order waves and free waves propagating slightly slower. Introducing secondary paddle motions suppressed the free waves, better matching second-order theory. Random waves were also generated based on field-measured spectral densities and analyzed through power spectra.
Transverse relaxation time fractal dimension of nuclear magnetic resonance fo...Khalid Al-Khidir
Transverse relaxation time fractal dimension of nuclear magnetic resonance for characterizing shajara reservoirs of the permo carboniferous shajara formation, saudi arabia
Pipe flow involves fluid completely filling a pipe, while open channel flow has a free surface. In pipe flow, pressure varies along the pipe but remains constant at the free surface in open channels. The main driving force is gravity in open channels and pressure gradient in pipes. Flow properties like cross-sectional area and velocity profile differ between the two flow types.
The document discusses various topics related to the transfer of heat, including:
1. The three main modes of heat transfer are conduction, convection, and radiation. Conduction involves the transfer of heat between particles without particle movement, convection involves heat transfer via actual particle movement, and radiation transfers heat directly via electromagnetic waves.
2. When thermal radiation falls on an object, it can be absorbed, transmitted, or reflected. The absorptance, transmittance, and reflectance of an object describe these properties.
3. Blackbody radiation follows several laws, including Wien's displacement law and Stefan's law. Wien's law states the wavelength of peak emission is inversely proportional to temperature,
Wind from the_black_hole_accretion_disk_driving_a_molecular_outflow_in_an_act...Sérgio Sacani
Artigo descreve estudo inédito que mostra que os ventos gerados pelos buracos negros nos centros das galáxias pode acabar com o processo de formação de estrelas nas galáxias hospedeiras.
This document summarizes the research investigating the effect of longitudinal atmospheric turbulence on the dynamics of an airfoil with a structural nonlinearity in pitch. Three different regions of dynamic behavior are observed when the airfoil is excited by longitudinal turbulence, compared to two regions for the nonexcited case. A new region exists where the airfoil response is concentrated about the equilibrium position, attributed to the parametric nature of the turbulence excitation. Utter occurs at a lower velocity and limit cycle oscillations occur at a higher velocity for the excited case versus the nonexcited case. The airfoil and aerodynamic models used in the numerical simulations are described.
The document summarizes an experiment on determining the state of open channel flow. It includes the background, objectives to determine flow state, critical depth, and Reynolds and Froude numbers. The experimental setup used a flume and point gauge to measure depth upstream and downstream of a weir. Flow was found to be subcritical transitional at section 1 and supercritical transitional at section 2, based on calculated Reynolds and Froude numbers. The critical depth was also calculated.
This document discusses four types of boundaries encountered in steady-state groundwater flow through homogeneous soils:
1. Impervious boundaries, where flow cannot penetrate or leave the boundary.
2. Reservoir boundaries, where the pressure distribution is hydrostatic and equipotential lines define the boundary.
3. Surfaces of seepage, where seepage leaves the flow region and enters an unfilled zone, resulting in a linear relationship between pressure and elevation.
4. Lines of seepage (free surfaces or depression curves), which separate saturated and unsaturated zones and require constant pressure and elevation changes along the boundary.
1) The document discusses various equations and concepts in hydraulics including the continuity equation, Bernoulli's equation, conservation of momentum, uniform flow in open channels, and Manning's formula.
2) The continuity equation states that the mass of fluid passing per unit time through an area is equal to the product of the flow velocity and cross-sectional area.
3) Bernoulli's equation relates the total energy of flowing water through different cross-sections in terms of pressure, elevation, and velocity.
This document discusses fluid kinematics, which is the branch of fluid mechanics that deals with the geometry of motion of fluids without considering forces or energies. It describes Lagrangian and Eulerian methods for describing fluid motion, defines types of flow such as laminar, turbulent, steady, and unsteady. It also discusses concepts like acceleration fields, circulation, vorticity, streamlines, pathlines, streaklines, stream functions, and velocity potential functions. Flow nets, which use a grid of streamlines and equipotential lines, are introduced as a way to study two-dimensional irrotational flows.
The document describes the design and development of a shockwave tube to study blast-induced neurological impairments. The shockwave tube uses a diaphragm to separate high and low pressure gas sections. When the diaphragm bursts, it produces a shockwave that propagates down the tube into the low pressure section. Pressure transducers measure the speed and pressure changes of the shockwaves. Data is collected on shockwaves created by varying the diaphragm material and initial gas pressures.
1) The document discusses fluid flow through orifices and mouthpieces. It describes the theory of small orifices discharging fluid using Bernoulli's equation and defines relevant terms like coefficient of velocity and coefficient of discharge.
2) Torricelli's theorem states the velocity of a discharging jet is proportional to the square root of the head producing flow. The theoretical discharge can be calculated using the orifice area and velocity.
3) Examples are provided to demonstrate calculating coefficients of velocity, discharge, and contraction for given orifice dimensions and fluid flow values.
This document discusses open channel flow. It begins by defining open channel flow as flow where the surface is open to the atmosphere, with only atmospheric pressure at the surface. It then classifies open channel flows as being either artificial or natural channels. It further classifies flows as being steady or unsteady, uniform or non-uniform, laminar or turbulent, subcritical, critical, or supercritical. The document also discusses gradually varied and rapidly varied flow, and defines geometric properties of open channels such as depth, width, perimeter, and hydraulic radius. It concludes by discussing the most economical channel sections.
This document discusses surface runoff, stream flow, hydrographs, and unit hydrographs. It begins by defining surface runoff and stream flow, explaining that surface runoff occurs when precipitation is unable to infiltrate the ground and flows overland into streams, rivers, and other bodies of water. It then discusses measuring stream flow through various methods like current meters and weirs to determine discharge. The document introduces the concept of hydrographs, which plot discharge over time, and unit hydrographs, which represent the hydrograph resulting from 1 unit of excess precipitation. It provides examples of using unit hydrographs and the S-curve method to develop hydrographs of different durations.
The document discusses wind energy and wind turbines. It begins by explaining how wind is formed from pressure gradients and the Coriolis effect. It then discusses different types of winds and how wind speed and patterns vary over time. Methods for measuring wind are presented, including wind atlases. The basics of how wind power is captured by wind turbines are covered, including swept area, power output formulas, and optimal turbine spacing in wind farms. Environmental impacts and public acceptance issues are also summarized.
In situ observations_of_interstellar_plasma_with_voyager_1Sérgio Sacani
Voyager 1 detected electron plasma oscillations beginning in April 2013 at a frequency corresponding to an electron density of 0.08 cm-3. This provides evidence that Voyager 1 has crossed into the nearby interstellar plasma, as the density is much higher than what is expected in the heliosheath. Comparison with radio emissions detected in 1992 suggests Voyager 1 has encountered a smoothly increasing plasma density ramp, as the frequency drift matches what was observed remotely. Estimating the shock propagation speed that would be required to produce the 1992 drift indicates a plausible speed of 40 km/s.
Evidence of a plume on Europa from Galileo magnetic and plasma wave signaturesSérgio Sacani
The icy surface of Jupiter’s moon, Europa, is thought to lie
on top of a global ocean1–4. Signatures in some Hubble Space
Telescope images have been associated with putative water
plumes rising above Europa’s surface5,6, providing support for
the ocean theory. However, all telescopic detections reported
were made at the limit of sensitivity of the data5–7
, thereby calling
for a search for plume signatures in in-situ measurements.
Here, we report in-situ evidence of a plume on Europa from
the magnetic field and plasma wave observations acquired on
Galileo’s closest encounter with the moon. During this flyby,
which dropped below 400 km altitude, the magnetometer8
recorded an approximately 1,000-kilometre-scale field rotation
and a decrease of over 200 nT in field magnitude, and
the Plasma Wave Spectrometer9 registered intense localized
wave emissions indicative of a brief but substantial increase
in plasma density. We show that the location, duration and
variations of the magnetic field and plasma wave measurements
are consistent with the interaction of Jupiter’s corotating
plasma with Europa if a plume with characteristics inferred
from Hubble images were erupting from the region of Europa’s
thermal anomalies. These results provide strong independent
evidence of the presence of plumes at Europa.
Physical significance of non dimensional numbersvaibhav tailor
This document discusses four non-dimensional numbers that are used in heat transfer analysis:
The Nusselt number relates convective heat transfer to conductive heat transfer through a characteristic length and thermal conductivity. The Grashof number compares buoyancy and inertia forces to viscous forces in natural convection. The Prandtl number is the ratio of momentum diffusivity to thermal diffusivity, relating how a fluid conducts momentum and heat. The Reynolds number compares inertial to viscous forces, indicating flow regime from laminar to turbulent. These non-dimensional numbers provide insight into dominant transfer mechanisms in heat transfer problems.
1. Heat transfer occurs through three methods: conduction, convection, and radiation.
2. Conduction involves the transfer of heat through direct contact of particles. Convection involves the transfer of heat by fluid motion. Radiation involves heat transfer through electromagnetic waves without a medium.
3. Heat transfer is important across several engineering disciplines for applications like cooling systems, fluid heating/cooling, building design, and engines.
The document provides an overview of wind energy and wind turbine technology. It outlines the objectives to understand wind measurement and analysis, the workings of wind turbines and their components. The key sources and characteristics of wind are described, including types of wind patterns and how wind speed varies with location, time and height. Methods for measuring and analyzing wind resources at potential wind farm sites are also summarized.
Reconfinement and loss of stability in jets from active galactic nucleiSérgio Sacani
ets powered by active galactic nuclei appear impressively stable compared with their terrestrial and laboratory coun-terparts—they can be traced from their origin to distances exceeding their injection radius by up to a billion times1,2. However, some less energetic jets get disrupted and lose their coherence on the scale of their host galaxy1,3. Quite remark-ably, on the same scale, these jets are expected to become confined by the thermal pressure of the intra-galactic gas2. Motivated by these observations, we have started a system-atic study of active galactic nuclei jets undergoing reconfine-ment via computer simulations. Here, we show that in the case of unmagnetized relativistic jets, the reconfinement is accom-panied by the development of an instability and transition to a turbulent state. During their initial growth, the perturba-tions have a highly organized streamwise-oriented structure, indicating that it is not the Kelvin–Helmholtz instability, the instability which has been the main focus of the jet stability studies so far4,5. Instead, it is closely related to the centrifugal instability6. This instability is likely to be behind the division of active galactic nuclei jets into two morphological types in the Fanaroff–Riley classification7.
In this study the kinematic wave equation has been solved numerically using the modified Lax
explicit finite difference scheme (MLEFDS) and used for flood routing in a wide prismatic channel and a nonprismatic
channel. Two flood waves, one sinusoidal wave and one exponential wave, have been imposed at the
upstream boundary of the channel in which the flow is initially uniform. Six different schemes have been
introduced and used to compute the routing parameter, the wave celerity c. Two of these schemes are based on
constant depth and use constant celerity throughout the computation process. The rest of the schemes are based
on local depths and give celerity dependent on time and space. The effects of the routing parameter c on the
travel time of flood wave, the subsidence of the flood peak and the conservation flood flow volume have been
studied. The results seem to indicate that there is a minimal loss/gain of flow volume whatever the scheme is.
While it is confirmed that neither of the schemes is 100% volume conservative, it is found that the scheme
Kinematic Wave Model-2 (KWM-II) gives the most accurate result giving only 0.1% error in perspective of
volume conservation. The results obtained in this study are in good qualitative agreement with those obtained in
other similar studies.
The document summarizes wave generation studies conducted in a 3D wave basin. Periodic waves were generated using sinusoidal paddle motions to study propagation properties at different locations. Two second-order wave components were identified through Fourier analysis: bounded waves propagating at the same speed as first-order waves and free waves propagating slightly slower. Introducing secondary paddle motions suppressed the free waves, better matching second-order theory. Random waves were also generated based on field-measured spectral densities and analyzed through power spectra.
Transverse relaxation time fractal dimension of nuclear magnetic resonance fo...Khalid Al-Khidir
Transverse relaxation time fractal dimension of nuclear magnetic resonance for characterizing shajara reservoirs of the permo carboniferous shajara formation, saudi arabia
Pipe flow involves fluid completely filling a pipe, while open channel flow has a free surface. In pipe flow, pressure varies along the pipe but remains constant at the free surface in open channels. The main driving force is gravity in open channels and pressure gradient in pipes. Flow properties like cross-sectional area and velocity profile differ between the two flow types.
The document discusses various topics related to the transfer of heat, including:
1. The three main modes of heat transfer are conduction, convection, and radiation. Conduction involves the transfer of heat between particles without particle movement, convection involves heat transfer via actual particle movement, and radiation transfers heat directly via electromagnetic waves.
2. When thermal radiation falls on an object, it can be absorbed, transmitted, or reflected. The absorptance, transmittance, and reflectance of an object describe these properties.
3. Blackbody radiation follows several laws, including Wien's displacement law and Stefan's law. Wien's law states the wavelength of peak emission is inversely proportional to temperature,
Wind from the_black_hole_accretion_disk_driving_a_molecular_outflow_in_an_act...Sérgio Sacani
Artigo descreve estudo inédito que mostra que os ventos gerados pelos buracos negros nos centros das galáxias pode acabar com o processo de formação de estrelas nas galáxias hospedeiras.
This document summarizes the research investigating the effect of longitudinal atmospheric turbulence on the dynamics of an airfoil with a structural nonlinearity in pitch. Three different regions of dynamic behavior are observed when the airfoil is excited by longitudinal turbulence, compared to two regions for the nonexcited case. A new region exists where the airfoil response is concentrated about the equilibrium position, attributed to the parametric nature of the turbulence excitation. Utter occurs at a lower velocity and limit cycle oscillations occur at a higher velocity for the excited case versus the nonexcited case. The airfoil and aerodynamic models used in the numerical simulations are described.
The document summarizes an experiment on determining the state of open channel flow. It includes the background, objectives to determine flow state, critical depth, and Reynolds and Froude numbers. The experimental setup used a flume and point gauge to measure depth upstream and downstream of a weir. Flow was found to be subcritical transitional at section 1 and supercritical transitional at section 2, based on calculated Reynolds and Froude numbers. The critical depth was also calculated.
This document discusses four types of boundaries encountered in steady-state groundwater flow through homogeneous soils:
1. Impervious boundaries, where flow cannot penetrate or leave the boundary.
2. Reservoir boundaries, where the pressure distribution is hydrostatic and equipotential lines define the boundary.
3. Surfaces of seepage, where seepage leaves the flow region and enters an unfilled zone, resulting in a linear relationship between pressure and elevation.
4. Lines of seepage (free surfaces or depression curves), which separate saturated and unsaturated zones and require constant pressure and elevation changes along the boundary.
1) The document discusses various equations and concepts in hydraulics including the continuity equation, Bernoulli's equation, conservation of momentum, uniform flow in open channels, and Manning's formula.
2) The continuity equation states that the mass of fluid passing per unit time through an area is equal to the product of the flow velocity and cross-sectional area.
3) Bernoulli's equation relates the total energy of flowing water through different cross-sections in terms of pressure, elevation, and velocity.
This document discusses fluid kinematics, which is the branch of fluid mechanics that deals with the geometry of motion of fluids without considering forces or energies. It describes Lagrangian and Eulerian methods for describing fluid motion, defines types of flow such as laminar, turbulent, steady, and unsteady. It also discusses concepts like acceleration fields, circulation, vorticity, streamlines, pathlines, streaklines, stream functions, and velocity potential functions. Flow nets, which use a grid of streamlines and equipotential lines, are introduced as a way to study two-dimensional irrotational flows.
The document describes the design and development of a shockwave tube to study blast-induced neurological impairments. The shockwave tube uses a diaphragm to separate high and low pressure gas sections. When the diaphragm bursts, it produces a shockwave that propagates down the tube into the low pressure section. Pressure transducers measure the speed and pressure changes of the shockwaves. Data is collected on shockwaves created by varying the diaphragm material and initial gas pressures.
1) The document discusses fluid flow through orifices and mouthpieces. It describes the theory of small orifices discharging fluid using Bernoulli's equation and defines relevant terms like coefficient of velocity and coefficient of discharge.
2) Torricelli's theorem states the velocity of a discharging jet is proportional to the square root of the head producing flow. The theoretical discharge can be calculated using the orifice area and velocity.
3) Examples are provided to demonstrate calculating coefficients of velocity, discharge, and contraction for given orifice dimensions and fluid flow values.
This document discusses open channel flow. It begins by defining open channel flow as flow where the surface is open to the atmosphere, with only atmospheric pressure at the surface. It then classifies open channel flows as being either artificial or natural channels. It further classifies flows as being steady or unsteady, uniform or non-uniform, laminar or turbulent, subcritical, critical, or supercritical. The document also discusses gradually varied and rapidly varied flow, and defines geometric properties of open channels such as depth, width, perimeter, and hydraulic radius. It concludes by discussing the most economical channel sections.
This document discusses surface runoff, stream flow, hydrographs, and unit hydrographs. It begins by defining surface runoff and stream flow, explaining that surface runoff occurs when precipitation is unable to infiltrate the ground and flows overland into streams, rivers, and other bodies of water. It then discusses measuring stream flow through various methods like current meters and weirs to determine discharge. The document introduces the concept of hydrographs, which plot discharge over time, and unit hydrographs, which represent the hydrograph resulting from 1 unit of excess precipitation. It provides examples of using unit hydrographs and the S-curve method to develop hydrographs of different durations.
The document discusses wind energy and wind turbines. It begins by explaining how wind is formed from pressure gradients and the Coriolis effect. It then discusses different types of winds and how wind speed and patterns vary over time. Methods for measuring wind are presented, including wind atlases. The basics of how wind power is captured by wind turbines are covered, including swept area, power output formulas, and optimal turbine spacing in wind farms. Environmental impacts and public acceptance issues are also summarized.
In situ observations_of_interstellar_plasma_with_voyager_1Sérgio Sacani
Voyager 1 detected electron plasma oscillations beginning in April 2013 at a frequency corresponding to an electron density of 0.08 cm-3. This provides evidence that Voyager 1 has crossed into the nearby interstellar plasma, as the density is much higher than what is expected in the heliosheath. Comparison with radio emissions detected in 1992 suggests Voyager 1 has encountered a smoothly increasing plasma density ramp, as the frequency drift matches what was observed remotely. Estimating the shock propagation speed that would be required to produce the 1992 drift indicates a plausible speed of 40 km/s.
Evidence of a plume on Europa from Galileo magnetic and plasma wave signaturesSérgio Sacani
The icy surface of Jupiter’s moon, Europa, is thought to lie
on top of a global ocean1–4. Signatures in some Hubble Space
Telescope images have been associated with putative water
plumes rising above Europa’s surface5,6, providing support for
the ocean theory. However, all telescopic detections reported
were made at the limit of sensitivity of the data5–7
, thereby calling
for a search for plume signatures in in-situ measurements.
Here, we report in-situ evidence of a plume on Europa from
the magnetic field and plasma wave observations acquired on
Galileo’s closest encounter with the moon. During this flyby,
which dropped below 400 km altitude, the magnetometer8
recorded an approximately 1,000-kilometre-scale field rotation
and a decrease of over 200 nT in field magnitude, and
the Plasma Wave Spectrometer9 registered intense localized
wave emissions indicative of a brief but substantial increase
in plasma density. We show that the location, duration and
variations of the magnetic field and plasma wave measurements
are consistent with the interaction of Jupiter’s corotating
plasma with Europa if a plume with characteristics inferred
from Hubble images were erupting from the region of Europa’s
thermal anomalies. These results provide strong independent
evidence of the presence of plumes at Europa.
Voyager 1 Observes Low-Energy Galactic Cosmic Rays in a Region Depleted of He...Carlos Bella
Voyager 1 entered a region outside the heliosphere on August 25, 2012 where energetic ions from within the heliosphere disappeared and low energy cosmic rays from outside the heliosphere increased. While the magnetic field direction did not change, indicating Voyager 1 was still within the heliosphere, it had likely crossed into a depletion region devoid of energetic ions. Observations show decreases in ions from the heliosphere and increases in galactic cosmic rays, electrons, and magnetic field strength. Analysis of particle intensities and spectra provide evidence that Voyager 1 is observing galactic cosmic rays with minimal heliospheric modulation for the first time. The hydrogen to helium ratio is consistent with the solar photosphere abundance, differing
Voyager 1 observed changes in cosmic ray intensities on August 25, 2012 when it was 122 AU from the Sun, indicating it had entered a new region outside the heliosphere still dominated by the Sun's magnetic field. Energetic particles from inside the heliosphere disappeared, while intensities of low-energy galactic cosmic rays increased. Analysis of cosmic ray spectra revealed hydrogen and helium spectra peaking between 10-40 MeV/nucleon, consistent with abundances in the solar photosphere. This provides the first direct measurements of low-energy galactic cosmic rays outside of Earth's environment.
Search for the Exit: Voyager 1 at Heliosphere’s Border with the Galaxy.Carlos Bella
Voyager 1 has detected changes in energetic particle intensities that suggest it has reached the outer boundary of the heliosphere and entered interstellar space. Measurements show a sudden decrease in particles of solar origin by over 100 times on August 25, 2012, while galactic cosmic rays increased by 9.3% at the same time. This indicates Voyager 1 has reached a region dominated by interstellar plasma rather than heated solar plasma. The spacecraft is now detecting unexpected anisotropies in cosmic rays and temporary increases that may be associated with large solar storms, implying it is still within a transitional region to the local interstellar medium.
Search for the_exit_voyager1_at_heliosphere_border_with_the_galaxySérgio Sacani
Voyager 1 has detected changes in energetic particle intensities that suggest it has reached the outer boundary of the heliosphere and entered interstellar space. Measurements show a sudden decrease in particles of solar origin by over 100 times on August 25, 2012, while galactic cosmic rays increased by 9.3% at the same time. This indicates Voyager 1 has reached a region dominated by interstellar plasma rather than heated solar plasma. The spacecraft is now detecting unexpected anisotropies in cosmic rays and temporary increases that may be associated with large solar storms, implying it is still within a transitional region to the local interstellar medium.
Role of Magnetic Reconnection in Coronal Heatingijtsrd
The outermost atmosphere of the Sun, called the corona, is some 200 times hotter than the surface of the Sun. The main source of energy for heating the corona is believed to be the magnetic field which dominates the corona. Magnetic reconnection is probably the most important mechanism for releasing magnetic energy and may, therefore, be important for coronal heating or micro flaring. The best observational examples of reconnection in the corona are thought to be X ray bright points, which are small scale brightenings seen randomly throughout the whole corona. Theoretical models can not only explain the key observations relating to bright points, but they can also explain the complex three dimensional structures often seen in bright points. In these models magnetic neutral points play a significant role as the centres for reconnection both in two and three dimensions. Dr. Aradhna Sharma "Role of Magnetic Reconnection in Coronal Heating" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-6 | Issue-4 , June 2022, URL: https://www.ijtsrd.com/papers/ijtsrd50179.pdf Paper URL: https://www.ijtsrd.com/physics/other/50179/role-of-magnetic-reconnection-in-coronal-heating/dr-aradhna-sharma
1) Streamer theory was proposed in 1940 by Rather, Meek and Loeb to explain phenomena not accounted for by Townsend's theory of gas breakdown, such as dependence on gas pressure and geometry.
2) Streamer theory describes how a single avalanche can develop into a spark discharge through distortion of the electric field by space charge, generating further avalanches cumulatively at the avalanche head.
3) Positive ions are left behind the rapidly advancing avalanche head, enhancing the field in front and reducing it behind, while the field is also enhanced between the tail and cathode. This leads to further space charge increase and field enhancement around the anode, forming a streamer connecting anode to cathode.
Discovery of rapid whistlers close to Jupiter implying lightning rates simila...Sérgio Sacani
Electrical currents in atmospheric lightning strokes generate
impulsive radio waves in a broad range of frequencies, called
atmospherics. These waves can be modified by their passage
through the plasma environment of a planet into the form of
dispersed whistlers1. In the Io plasma torus around Jupiter,
Voyager 1 detected whistlers as several-seconds-long slowly
falling tones at audible frequencies2. These measurements
were the first evidence of lightning at Jupiter. Subsequently,
Jovian lightning was observed by optical cameras on board
several spacecraft in the form of localized flashes of light3–7.
Here, we show measurements by the Waves instrument8
on board the Juno spacecraft9–11 that indicate observations
of Jovian rapid whistlers: a form of dispersed atmospherics
at extremely short timescales of several milliseconds to
several tens of milliseconds. On the basis of these measurements,
we report over 1,600 lightning detections, the largest
set obtained to date. The data were acquired during close
approaches to Jupiter between August 2016 and September
2017, at radial distances below 5 Jovian radii. We detected up
to four lightning strokes per second, similar to rates in thunderstorms
on Earth12 and six times the peak rates from the
Voyager 1 observations13.
The document discusses streamer theory, which overcomes some limitations of Townsend's theory in explaining electric breakdown. Streamer theory proposes that a single avalanche can develop directly into a spark discharge due to the effects of space charge fields and photoionization. As electrons move rapidly through the gas, they leave behind a trail of slower positive ions, enhancing the electric field in front and behind the avalanche head. This leads to further avalanches and the formation of a streamer discharge between the electrodes. Meek provided a quantitative model to estimate the electric field needed to transform an avalanche into a streamer.
H-mode-like confinement formation in the RF discharge plasma in the Uragan-3M...Aleksey Beletskii
This PhD thesis studied plasma confinement and heating in the Uragan-3M torsatron device. Experiments varied RF power levels and plasma densities. At RF powers over 100 kW and densities around 1.2×1012 cm-3, signs of improved confinement similar to the H-mode transition were observed, including increased density, temperature, and stored energy. Faster processes like an electric field bifurcation and turbulence suppression triggered the transition, while slower processes like increasing fast ion content and density decay preceded it. Detailed edge plasma turbulence measurements found fluctuations suppressed after the transition. The fast ion loss appears to trigger the transition by initiating the electric field bifurcation. Further study of fast ion generation mechanisms could provide more insight.
Electrostatic Edge Plasma Turbulence in the Uragan-3M torsatronAleksey Beletskii
The document summarizes electrical probe measurements of electrostatic edge plasma turbulence in the Uragan-3M torsatron. Key findings include: (1) plasma density fluctuations in the scrape-off layer and divertor region exhibit a spectral splitting depending on position relative to the last closed magnetic surface; (2) formation of radial electric field shear decreases turbulence and anomalous transport at the plasma edge; (3) turbulence data from Uragan-3M is included in the International Stellarator/Heliotron Edge Turbulence Database. Future work involves direct measurements of plasma potential and electron temperature fluctuations using a new combined probe.
Inverse Compton cooling limits the brightness temperature of the radiating plasma to a maximum of
1011.5 K. Relativistic boosting can increase its observed value, but apparent brightness temperatures
much in excess of 1013 K are inaccessible using ground-based very long baseline interferometry (VLBI)
at any wavelength. We present observations of the quasar 3C 273, made with the space VLBI mission
RadioAstron on baselines up to 171,000 km, which directly reveal the presence of angular structure as
small as 26 µas (2.7 light months) and brightness temperature in excess of 1013 K. These measurements
challenge our understanding of the non-thermal continuum emission in the vicinity of supermassive
black holes and require a much higher Doppler factor than what is determined from jet apparent
kinematics.
Keywords: galaxies: active — galaxies: jets — radio continuum: galaxies — techniques: interferometric
— quasars: individual (3C 273)
This document summarizes research analyzing data from the Van Allen Probes and BARREL (Balloon Array for Radiation Belt Relativistic Electron Losses) campaigns to further understand global coherence in radiation belt electron loss modulated by plasmaspheric hiss. Analysis of data from 71 balloon payload combinations found significant coherence around noon, likely caused by solar wind structures impacting the bow shock and creating compressional waves propagating through the magnetosphere. This research aims to better understand how ultra-low frequency waves originating in the solar wind can cause nearly global-scale coherence in electron loss.
Artigo que descreve o trabalho feito com o Chandra nos aglomerados de galáxias de Perseus e Virgo sobre a descoberta de uma turbulência cósmica que impede a formação de novas estrelas.
Uma equipe de astrônomos norte-americanos descobriu o par de buracos negros supermassivos mais próximos até agora no universo.
O par de buracos negros está localizado no centro do quasar chamado de PKS 1302-102, a aproximadamente 3.5 bilhões de anos-luz de distância.
Esses dois buracos negros estão separados de apenas uma semana-luz e estão num movimento espiral um em direção ao outro que deve acabar com uma colisão cataclísmica.
Em contraste, o par de buracos negros mais próximos descoberto até então estava separado de aproximadamente 20 anos-luz.
Pulsar emission amplified and resolved by plasma lensing in an eclipsing binarySérgio Sacani
Radio pulsars scintillate because their emission travels through the
ionized interstellar medium along multiple paths, which interfere
with each other. It has long been realized that, independent of their
nature, the regions responsible for the scintillation could be used
as ‘interstellar lenses’ to localize pulsar emission regions1,2
. Most
such lenses, however, resolve emission components only marginally,
limiting results to statistical inferences and detections of small
positional shifts3–5
. As lenses situated close to their source offer
better resolution, it should be easier to resolve emission regions of
pulsars located in high-density environments such as supernova
remnants6
or binaries in which the pulsar’s companion has an
ionized outflow. Here we report observations of extreme plasma
lensing in the ‘black widow’ pulsar, B1957+20, near the phase in its
9.2-hour orbit at which its emission is eclipsed by its companion’s
outflow7–9
. During the lensing events, the observed radio flux is
enhanced by factors of up to 70–80 at specific frequencies. The
strongest events clearly resolve the emission regions: they affect the
narrow main pulse and parts of the wider interpulse differently. We
show that the events arise naturally from density fluctuations in
the outer regions of the outflow, and we infer a resolution of our
lenses that is comparable to the pulsar’s radius, about 10 kilometres.
Furthermore, the distinct frequency structures imparted by the
lensing are reminiscent of what is observed for the repeating fast
radio burst FRB 121102, providing observational support for the
idea that this source is observed through, and thus at times strongly
magnified by, plasma lenses10
Interchange reconnection as the source of the fast solar wind within coronal ...Sérgio Sacani
1) Recent measurements from Parker Solar Probe showed that the fast solar wind emerging from coronal holes is organized into 'microstreams' with an angular scale similar to underlying supergranulation cells associated with horizontal flows in the photosphere.
2) During a solar encounter where Parker Solar Probe came within 12.3 solar radii of the photosphere, plasma, energetic ion, and magnetic field measurements showed discrete microstreams structured at scales of supergranulation, with associated switchbacks of the radial magnetic field.
3) Correlation of the microstream and switchback structure with the spatial periodicity of the surface magnetic field suggests that interchange reconnection between open and closed magnetic fields in the low corona is driving the bursts observed by
The team detected signals from the Magellanic Stream using the 4.5m radio telescope at Leuschner Observatory. Images of the observed region in galactic coordinates showed high-velocity gases from -100 to -350 km/s, consistent with the Magellanic Stream. A velocity map matched previous studies, and higher intensities near the galactic pole aligned with expectations. Issues with intensity calibration and single polarization data collection impacted accuracy but detection of the stream was achieved.
Propagation of ELF Radiation from RS-LC System and Red Sprites in Earth- Iono...degarden
This document compares the propagation of extremely low frequency (ELF) radiation from return stroke-lateral corona (RS-LC) systems and red sprites in the Earth-ionosphere waveguide. It finds that red sprites contribute more greatly to Schumann resonances than RS-LC systems. The document derives mathematical expressions to model the velocity, current, and current moment of RS-LC systems and red sprites. It then uses these expressions to calculate the electric and magnetic fields generated by RS-LC systems and red sprites, finding that red sprites produce fields on the order of 10-5 V/m and 10-8 A/m, peaking at Schumann resonance frequencies.
Similar to Voyager 2 plasma observations of the heliopause (20)
The Enchantment of the Alien: Metaphysics and Marginality in Late Medieval an...Felipe Hime
This article examines why certain marginalized groups in late medieval and early modern Europe, such as executioners, gravediggers, and gypsies, were believed to have magical powers. It proposes that this was due to a complex set of interrelated factors that varied between regions and societies. Some individuals within these groups may have actually engaged in magical practices, contributing to beliefs about their supernatural associations. However, the article notes that it is difficult to determine the full extent and nature of these beliefs due to fragmented source documentation. It explores several reasons why marginalized people were thought to possess magical or demonic attributes, such as being associated with places like gallows hills or graveyards. The article argues this phenomenon took on added
Search for Interstellar Communication 1959Felipe Hime
This very short document does not contain any substantive information to summarize in 3 sentences or less. It only contains a copyright statement repeated three times without any additional context or content.
Brazil and Argentina have the most established space programs in South America. The paper reviews the history of space activities in each South American country from the 1960s onward. It discusses efforts to develop regional cooperation, including proposals for a South American Space Agency. While progress has been modest due to limited budgets and resources, countries have launched scientific satellites and developed space science and technology capabilities. The future of space activities in the region will depend on furthering regional collaboration on projects.
Alfvenic velocity spikes and rotational flowsFelipe Hime
1) The Parker Solar Probe observed the solar wind near the Sun during its first two encounters at heliocentric distances of around 35 solar radii.
2) The observations found Alfvénic fluctuations in the solar wind that were organized into velocity spikes lasting minutes associated with propagating S-shaped bends in the magnetic field lines.
3) An increasing rotational component to the solar wind velocity was detected, peaking at 35-50 km/s around the Sun - considerably above the amplitude of the waves - challenging models of circulation in the corona.
A measurement of water vapour amid a largelyFelipe Hime
- Galileo observations of Europa showed its surface consists of chaotic terrains like pits, domes, and irregular uplifts, suggesting Europa contains a global ocean under an icy crust.
- The authors conducted a survey from 2016-2017 using infrared spectroscopy at the Keck Observatory to directly measure water vapor on Europa, resulting in non-detections on 16 of 17 dates with strict upper limits.
- On one date (April 26, 2016), a measurement of water vapor was detected at Europa's leading hemisphere, corresponding to a column density of 1.4×1019 H2O m-2 and a total water production rate exceeding previous exogenic estimates, suggesting an isolated localized endogenic plume event.
hematic appreciation test is a psychological assessment tool used to measure an individual's appreciation and understanding of specific themes or topics. This test helps to evaluate an individual's ability to connect different ideas and concepts within a given theme, as well as their overall comprehension and interpretation skills. The results of the test can provide valuable insights into an individual's cognitive abilities, creativity, and critical thinking skills
Authoring a personal GPT for your research and practice: How we created the Q...Leonel Morgado
Thematic analysis in qualitative research is a time-consuming and systematic task, typically done using teams. Team members must ground their activities on common understandings of the major concepts underlying the thematic analysis, and define criteria for its development. However, conceptual misunderstandings, equivocations, and lack of adherence to criteria are challenges to the quality and speed of this process. Given the distributed and uncertain nature of this process, we wondered if the tasks in thematic analysis could be supported by readily available artificial intelligence chatbots. Our early efforts point to potential benefits: not just saving time in the coding process but better adherence to criteria and grounding, by increasing triangulation between humans and artificial intelligence. This tutorial will provide a description and demonstration of the process we followed, as two academic researchers, to develop a custom ChatGPT to assist with qualitative coding in the thematic data analysis process of immersive learning accounts in a survey of the academic literature: QUAL-E Immersive Learning Thematic Analysis Helper. In the hands-on time, participants will try out QUAL-E and develop their ideas for their own qualitative coding ChatGPT. Participants that have the paid ChatGPT Plus subscription can create a draft of their assistants. The organizers will provide course materials and slide deck that participants will be able to utilize to continue development of their custom GPT. The paid subscription to ChatGPT Plus is not required to participate in this workshop, just for trying out personal GPTs during it.
Phenomics assisted breeding in crop improvementIshaGoswami9
As the population is increasing and will reach about 9 billion upto 2050. Also due to climate change, it is difficult to meet the food requirement of such a large population. Facing the challenges presented by resource shortages, climate
change, and increasing global population, crop yield and quality need to be improved in a sustainable way over the coming decades. Genetic improvement by breeding is the best way to increase crop productivity. With the rapid progression of functional
genomics, an increasing number of crop genomes have been sequenced and dozens of genes influencing key agronomic traits have been identified. However, current genome sequence information has not been adequately exploited for understanding
the complex characteristics of multiple gene, owing to a lack of crop phenotypic data. Efficient, automatic, and accurate technologies and platforms that can capture phenotypic data that can
be linked to genomics information for crop improvement at all growth stages have become as important as genotyping. Thus,
high-throughput phenotyping has become the major bottleneck restricting crop breeding. Plant phenomics has been defined as the high-throughput, accurate acquisition and analysis of multi-dimensional phenotypes
during crop growing stages at the organism level, including the cell, tissue, organ, individual plant, plot, and field levels. With the rapid development of novel sensors, imaging technology,
and analysis methods, numerous infrastructure platforms have been developed for phenotyping.
ESPP presentation to EU Waste Water Network, 4th June 2024 “EU policies driving nutrient removal and recycling
and the revised UWWTD (Urban Waste Water Treatment Directive)”
Travis Hills' Endeavors in Minnesota: Fostering Environmental and Economic Pr...Travis Hills MN
Travis Hills of Minnesota developed a method to convert waste into high-value dry fertilizer, significantly enriching soil quality. By providing farmers with a valuable resource derived from waste, Travis Hills helps enhance farm profitability while promoting environmental stewardship. Travis Hills' sustainable practices lead to cost savings and increased revenue for farmers by improving resource efficiency and reducing waste.
Current Ms word generated power point presentation covers major details about the micronuclei test. It's significance and assays to conduct it. It is used to detect the micronuclei formation inside the cells of nearly every multicellular organism. It's formation takes place during chromosomal sepration at metaphase.
The debris of the ‘last major merger’ is dynamically youngSérgio Sacani
The Milky Way’s (MW) inner stellar halo contains an [Fe/H]-rich component with highly eccentric orbits, often referred to as the
‘last major merger.’ Hypotheses for the origin of this component include Gaia-Sausage/Enceladus (GSE), where the progenitor
collided with the MW proto-disc 8–11 Gyr ago, and the Virgo Radial Merger (VRM), where the progenitor collided with the
MW disc within the last 3 Gyr. These two scenarios make different predictions about observable structure in local phase space,
because the morphology of debris depends on how long it has had to phase mix. The recently identified phase-space folds in Gaia
DR3 have positive caustic velocities, making them fundamentally different than the phase-mixed chevrons found in simulations
at late times. Roughly 20 per cent of the stars in the prograde local stellar halo are associated with the observed caustics. Based
on a simple phase-mixing model, the observed number of caustics are consistent with a merger that occurred 1–2 Gyr ago.
We also compare the observed phase-space distribution to FIRE-2 Latte simulations of GSE-like mergers, using a quantitative
measurement of phase mixing (2D causticality). The observed local phase-space distribution best matches the simulated data
1–2 Gyr after collision, and certainly not later than 3 Gyr. This is further evidence that the progenitor of the ‘last major merger’
did not collide with the MW proto-disc at early times, as is thought for the GSE, but instead collided with the MW disc within
the last few Gyr, consistent with the body of work surrounding the VRM.
When I was asked to give a companion lecture in support of ‘The Philosophy of Science’ (https://shorturl.at/4pUXz) I decided not to walk through the detail of the many methodologies in order of use. Instead, I chose to employ a long standing, and ongoing, scientific development as an exemplar. And so, I chose the ever evolving story of Thermodynamics as a scientific investigation at its best.
Conducted over a period of >200 years, Thermodynamics R&D, and application, benefitted from the highest levels of professionalism, collaboration, and technical thoroughness. New layers of application, methodology, and practice were made possible by the progressive advance of technology. In turn, this has seen measurement and modelling accuracy continually improved at a micro and macro level.
Perhaps most importantly, Thermodynamics rapidly became a primary tool in the advance of applied science/engineering/technology, spanning micro-tech, to aerospace and cosmology. I can think of no better a story to illustrate the breadth of scientific methodologies and applications at their best.
Remote Sensing and Computational, Evolutionary, Supercomputing, and Intellige...University of Maribor
Slides from talk:
Aleš Zamuda: Remote Sensing and Computational, Evolutionary, Supercomputing, and Intelligent Systems.
11th International Conference on Electrical, Electronics and Computer Engineering (IcETRAN), Niš, 3-6 June 2024
Inter-Society Networking Panel GRSS/MTT-S/CIS Panel Session: Promoting Connection and Cooperation
https://www.etran.rs/2024/en/home-english/
Unlocking the mysteries of reproduction: Exploring fecundity and gonadosomati...AbdullaAlAsif1
The pygmy halfbeak Dermogenys colletei, is known for its viviparous nature, this presents an intriguing case of relatively low fecundity, raising questions about potential compensatory reproductive strategies employed by this species. Our study delves into the examination of fecundity and the Gonadosomatic Index (GSI) in the Pygmy Halfbeak, D. colletei (Meisner, 2001), an intriguing viviparous fish indigenous to Sarawak, Borneo. We hypothesize that the Pygmy halfbeak, D. colletei, may exhibit unique reproductive adaptations to offset its low fecundity, thus enhancing its survival and fitness. To address this, we conducted a comprehensive study utilizing 28 mature female specimens of D. colletei, carefully measuring fecundity and GSI to shed light on the reproductive adaptations of this species. Our findings reveal that D. colletei indeed exhibits low fecundity, with a mean of 16.76 ± 2.01, and a mean GSI of 12.83 ± 1.27, providing crucial insights into the reproductive mechanisms at play in this species. These results underscore the existence of unique reproductive strategies in D. colletei, enabling its adaptation and persistence in Borneo's diverse aquatic ecosystems, and call for further ecological research to elucidate these mechanisms. This study lends to a better understanding of viviparous fish in Borneo and contributes to the broader field of aquatic ecology, enhancing our knowledge of species adaptations to unique ecological challenges.
Or: Beyond linear.
Abstract: Equivariant neural networks are neural networks that incorporate symmetries. The nonlinear activation functions in these networks result in interesting nonlinear equivariant maps between simple representations, and motivate the key player of this talk: piecewise linear representation theory.
Disclaimer: No one is perfect, so please mind that there might be mistakes and typos.
dtubbenhauer@gmail.com
Corrected slides: dtubbenhauer.com/talks.html
EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Weste...Sérgio Sacani
Context. With a mass exceeding several 104 M⊙ and a rich and dense population of massive stars, supermassive young star clusters
represent the most massive star-forming environment that is dominated by the feedback from massive stars and gravitational interactions
among stars.
Aims. In this paper we present the Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS) project, which aims to investigate
the influence of the starburst environment on the formation of stars and planets, and on the evolution of both low and high mass stars.
The primary targets of this project are Westerlund 1 and 2, the closest supermassive star clusters to the Sun.
Methods. The project is based primarily on recent observations conducted with the Chandra and JWST observatories. Specifically,
the Chandra survey of Westerlund 1 consists of 36 new ACIS-I observations, nearly co-pointed, for a total exposure time of 1 Msec.
Additionally, we included 8 archival Chandra/ACIS-S observations. This paper presents the resulting catalog of X-ray sources within
and around Westerlund 1. Sources were detected by combining various existing methods, and photon extraction and source validation
were carried out using the ACIS-Extract software.
Results. The EWOCS X-ray catalog comprises 5963 validated sources out of the 9420 initially provided to ACIS-Extract, reaching a
photon flux threshold of approximately 2 × 10−8 photons cm−2
s
−1
. The X-ray sources exhibit a highly concentrated spatial distribution,
with 1075 sources located within the central 1 arcmin. We have successfully detected X-ray emissions from 126 out of the 166 known
massive stars of the cluster, and we have collected over 71 000 photons from the magnetar CXO J164710.20-455217.
EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Weste...
Voyager 2 plasma observations of the heliopause
1. Articles
https://doi.org/10.1038/s41550-019-0929-2
1
Kavli Institute for Astrophysics and Space Research and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA. 2
Institute
of Physics, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland. 3
University of Maryland, Baltimore County, Baltimore, MD, USA.
*e-mail: jdr@space.mit.edu
T
he heliopause (HP), where the heliosphere and solar wind
end and the very local interstellar medium (VLISM) begins,
was first crossed by Voyager 1 (V1) at 121.7 au on 25 August
20121–4
. Voyager 2 (V2) crossed the HP at 119.0 au on 5 November
20185–8
. The V2 crossing is important scientifically because the V2
HP crossing occurred in a flow regime very different from that at
V1, and the bulk of the plasma particles were not observed by V1
as the plasma instrument on V1 is not working. V1 provided a very
surprising view of the heliosheath, with an extended 8 au stagna-
tion region with little plasma flow. V2 provides another view of this
region at a different location and time. The plasma and magnetic
field pressure in the VLISM combine to confine the solar wind
inside the heliosphere; these measurements help define the roles
each plays in this process. This paper describes and discusses the
first plasma observations upstream of the HP, at the HP, and in the
VLISM beyond the HP.
The Voyager Plasma Science (PLS) experiment measures ion and
electron currents with energy/charge 10–5,950 eV q−1
(ref. 9
). Three
Faraday cups (A, B and C) look at small angles to the sunward direc-
tion and a fourth (D) looks at right angles to this direction. These
cups can detect flows up to 60° from the cup normal. The space-
craft is oriented so that the D cup points as close as possible (55°)
to the direction of VLISM flow. Sets of ion spectra are obtained
every 192 s from both the lower-energy-resolution L mode and the
higher-energy-resolution M mode. In the heliosheath, the region of
shocked solar wind between the termination shock and HP, data are
often observed in three or four of the cups. These spectra are fitted
with convected isotropic proton Maxwellian distributions to deter-
mine the plasma velocity, density and temperature10
. In the VLISM,
currents are detected in only the sideways-looking D cup.
Heliospheric asymmetries
Figure 1 shows the V2 crossing of the HP. The L mode currents
from the three sunward-looking detectors are shown, from the low-
est energy channel (10–30 eV) for the A and C cups and the lowest
two energy channels (10–57 eV) for the B cup. The B cup points
closest to the heliosheath flow direction, followed by the C and A
cups, respectively. A boundary layer with enhanced currents signals
the approach to the HP starting on day 150, about 1.5 au ahead of
the HP. The currents in all three sunward-looking detectors started
decreasing near day 300 of 2018 and then fell to background levels
at the HP on day 309 (5 November). After this time V2 was no lon-
ger in the solar wind; it had entered the VLISM. The first crossing
of the HP by V1 at 121.7 au defined the scale size of the heliosphere;
the second crossing by V2 at 119.0 au shows that the HP distance
is similar in both the V1 and V2 directions despite the termination
shock being 10 au closer at V1 than V210
.
The Voyager HP crossings are both preceded by increases in
the Galactic cosmic ray (GCR) intensities4,5
and decreases in helio-
spheric electron and higher-energy ion intensities3,6
. The radial
speed of the solar wind at V1 went to near zero 8 au before the HP
crossing11
. Figure 2 shows the first observations of plasma in the
boundary region inside the HP. The plasma speed starts to decrease
and the density and temperature start to increase on day 150, about
1.5 au before the HP (blue dashed line). By day 200, the speed had
decreased from 130 to 100 km s−1
, the density increased by almost
a factor of two, and the temperature increased by 50%. This region
from day 200 to the HP contains the largest densities and lowest
speeds observed by V2 in the heliosheath. Near day 150, when the
plasma boundary region begins, the slope of the GCR intensities
increases slightly. V2 enters a region of enhanced magnetic field
called a magnetic barrier starting at day 229, 0.6 au ahead of the HP,
when the magnetic field and the GCR intensity start to increase5,7
.
This transition is not apparent in the plasma data. V2 previously
observed density increases associated with merged interaction
regions driven by solar transients, but unlike the density increases
in front of the HP, they were associated with speed and magnetic
field increases12,13
.
Figure3showsthevelocitycomponentsintheheliosheathderived
from the V2 PLS instrument at V2 and from the LECP11,14
and CRS15
instruments at V1. V1 and V2 are on opposite sides of the nose of
heliosphere in both the T and N directions, so V1 (V2) observed
Voyager 2 plasma observations of the heliopause
and interstellar medium
John D. Richardson 1
*, John W. Belcher1
, Paula Garcia-Galindo2
and Leonard F. Burlaga 3
The solar wind blows outwards from the Sun and forms a bubble of solar material in the interstellar medium. The heliopause
(HP) is the boundary that divides the hot tenuous solar wind plasma in the heliosheath from the colder, denser very local inter-
stellar medium (VLISM). The Voyager 2 plasma experiment observed the HP crossing from the solar wind into the VLISM on 5
November 2018 at 119 au. Here we present the first measurements of plasma at and near the HP and in the VLISM. A plasma
boundary region with a width of 1.5 au is observed before the HP. The plasma in the boundary region slows, heats up and is twice
as dense as typical heliosheath plasma. A much thinner boundary layer begins about 0.06 au inside the HP where the radial
speed decreases and the density and magnetic field increase. The HP transition occurs in less than one day. The VLISM is vari-
able near the HP and hotter than expected. Voyager 2 observations show that the temperature is 30,000–50,000 K, whereas
models and observations predicted a VLISM temperature of 15,000–30,000 K.
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negative (positive) T and positive (negative) N flow. To compare the
magnitudes of VT and VN at V1 and V2, the signs of VT and VN for
V1 are reversed in the plot. The data are plotted so that the termina-
tion shock and HP are at the same location for each spacecraft. The
difference between the V1 and V2 profiles is striking. The V1 VR is
much lower than that at V2 throughout the heliosheath and goes to
zero about 8 au before the HP. At V2, VR slowly decreases across the
heliosheath, then drops sharply just before the HP. The magnitude
of VT is also much larger at V2 than V1, whereas the magnitude of
VN decreases at both spacecraft before the HP. The differences in the
speed profiles at V1 and V2 are not understood.
HP boundary layer
Figure 4 in an enlargement of the region near the HP to show
the plasma density, velocity components and magnetic field BT.
These data show that a boundary layer is present in front of the HP
starting near day 302, about 0.06 au before the HP. In this bound-
ary layer, the density increases by a factor of two, the magnitudes
of VR and VN decrease, the flow angle in the RT plane increases,
and the magnitude of BT increases by 30%. The magnetic barrier is
an increase in magnetic field that extends 0.6 au ahead of the HP7
.
This region contains solar wind plasma that is modified near the
HP boundary.
Plasma in the VLISM
The PLS instrument observes currents from the VLISM plasma in
the D cup, but these measurements are difficult to conduct as the
average proton energies are comparable to the PLS energy threshold
of 10 eV, the expected flow is at the edge of the cup’s acceptance angle
and the data (especially in the D cup) are often contaminated by
noise. For the L mode, data are observed only in the lowest-energy
(10–30 eV) channel of the D cup. The M mode spectra have under-
lying systematic noise that varies and is larger than the expected
currents. Figure 5 shows 15-point running averages of the current in
the 10–30 eV channel of the D cup from spectra with minimal noise.
The dashed vertical line is the HP, where the currents drop. The cur-
rents in the VLISM vary from 30–70 fA (10−15
A), which could be
due to changes in speed, flow direction, density or temperature. The
region of increased currents from day 418–435 (22 February to 11
March 2019) starts at about the same time as the plasma oscillations
observed by the Plasma Wave (PWS) experiment cease8
, consistent
with a shock passing V2, as these oscillations are generated by elec-
tron beams upstream of a shock2
. The currents increase after day
430, which suggests that the density increases away from the HP, as
observed by V116
.
We want to determine the VLISM speed, density and tempera-
ture, but with one data point in each spectrum we cannot derive
these three quantities. However, in January 2019, the PWS experi-
ment observed plasma oscillations in the 1.78 kHz band8
, giving an
electron density of 0.039 ± 30% cm−3
. These oscillations persisted
from day 394 (29 January 2019) to roughly the time of the increase
in current at day 418 (22 February 2019). The observed PLS cur-
rents in the D cup during that period were 35–50 fA. We assume
that the electron and proton densities are roughly equal and use the
PWS-derived density to constrain VT, the flow towards the D cup
and the thermal speed or temperature of the protons. Figure 6 shows
contours of simulated proton currents in the D cup for a density of
0.04 cm−3
and a range VT values and temperatures. The speed of the
unperturbed LISM is about 26 km s−1
(ref. 17
); this flow is slowed
and deflected near the HP. The temperature far from the HP in the
VLISM is about 7,500 K (ref. 17
); models predict that this plasma is
compressed and heated by a factor of 2–4 near the HP18
, or more if
200
150
B cup
channels 1 + 2
HP
C cup, channel 1
A cup, channel 1
100 150 200
Day of 2018
250 300 350
100
Current(fA)
50
0
Fig. 1 | Current observed by the V2 PLS experiment in the three Faraday
cups that look sunwards. Energies from 10–57 eV are shown for the B cup,
which looks most closely towards the flow direction. For the A and C cups
the energy range 10–30 eV is shown. On day 150, V2 enters the plasma
boundary layer where the currents increase. At the HP (vertical dashed
line), the observed currents in all three cups fall to background levels as V2
leaves the solar wind and enters the VLISM.
HP
Plasma boundary
region
Magnetic
barrier
∣V∣(kms–1
)∣B∣(nT)
N(cm–3
)GCRintensities
(countss–1
)
T(K)
50
100
150
0
0.008
0.006
0.004
0.002
0
1 × 105
8 × 104
6 × 104
4 × 104
2 × 104
0
0.6
0.4
0.2
0
2.4
2.2
2.0
1.8
1.6
0 50 100 150
Day of 2018
200 250 300
Fig. 2 | Daily averages of solar wind speed, density, temperature,
magnetic field magnitude and GCR count rates. The plasma boundary
layer (dashed blue lines) extends 1.5 au from day 150 to the HP, with a
decrease in speed and increase in density and temperature. The GCR slope
increases slightly at the start of this region.
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it is also heated by reconnection in a plasma depletion layer19
. For
currents of 35–50 fA, the values of VT and temperature (T) are con-
strained to lie within the shaded region of Fig. 6. The range of VT
can be further constrained; the flow should slow near the HP and
only a component of the flow is in the VT plane. A reasonable upper
limit for VT is 15 km s−1
, which corresponds to T > 30,000 K, near the
upper limit predicted for T by models18
.
V2 occasionally rolls around the axis pointed towards Earth.
Three 360° rolls have occurred since the HP crossing, each last-
ing 2,000 s; the PLS instrument makes a measurement every 192 s,
so a roll provides about 10 measurements at different look direc-
tions, which (in principal) allows the determination of VT, T and
N. Figure 7 shows M mode currents measured in the D cup in two
energy channels from spacecraft rolls on days 22 and 164 of 2019.
The simulated currents show that when a roll begins, the D cup first
moves away from the plasma flow direction and the predicted cur-
rents decrease, then near the end of the roll the cup points closer
to the expected flow and currents increase, before the cup returns
to the original orientation. The currents in the D cup channels are
scaled to highlight the roll variations and are in qualitative agree-
ment with expectations. This signal is convincing evidence that PLS
is measuring the VLISM plasma. Removal of the noise affecting
these currents and fitting the VLISM plasma parameters are sub-
jects of future work.
Summary
V2crossedtheHPat119.0 au,similartothe121.7 audistancefromV1,
and is making the first plasma measurements in the VLISM. A 1.5-au-
thick plasma boundary region was discovered ahead of the HP with
lower speeds and enhanced densities and temperatures. The plasma
flow speed at V2 remained high just before the HP, in sharp contrast
to V1, for which a flow stagnation region was observed for 2 years
before the HP crossing. This difference suggests that V1 observations
may be anomalous, perhaps due to instabilities of the HP boundary.
The HP boundary was sharp, occurring over less than a day, with a
boundary layer observed to start about 8 days before the crossing. The
sharpness of the HP itself was expected, but accompanied by a more
95 100 105
V1 distance (au)
V2 PLS
V1 LECP
–V1 LECP
–V1 CRS
V2 PLS
V2 PLS
HP
TS
110 115 120
VR(kms–1
)VT(kms–1
)VN(kms–1
)
100
50
0
40
20
0
–20
–40
–60
–80
–100
80 90 100
V2 distance (au)
110 120
150
200
100
50
0
Fig. 3 | Plasma velocity components observed by V1 and V2 in the
heliosheath in the RTN coordinate system. In the RTN system, R is radially
outwards, T is parallel to the plane of the solar equator and positive in the
direction of the Sun’s rotation and N completes a right-handed system. The
vertical lines show the termination shock (TS) and HP crossings. V2 speeds
are from the plasma instrument and V1 speeds are derived from LECP
(VR and VT) and CRS (VN) data using the Compton–Getting effect. The signs
of VT and VN are reversed for the V1 data. The magnitudes of VR and VT are
much lower at V1 than V2 across the entire heliosheath. The stagnation
region observed at V1 where the speed approached zero for 8 au before the
HP was not observed at V2.
118.85 118.90 118.95
Distance from sun (au)
HP
VT
119.00
0.008
0.010
0.006
0.004
N(cm–3
)
VR,VT,VN(kms–1
)
BT(nT)
0.002
0
80
60
40
VR
VN
20
0
–20
–0.65
–0.60
–0.55
–0.50
–0.45
–0.40
290 295 300
Day of 2018
305 310
Fig. 4 | The HP boundary layer extends from day 302 to the HP. In this
boundary layer the density N increases, VR decreases (and since VT is
constant, the flow angle in the RT plane increases), and the magnetic field
BT increases. This layer has a width of 0.06 au. V1 VT and VN flow directions
are opposite those at V2; the plot shows negative values to facilitate
comparison of flow magnitudes. Error bars are the standard errors of the
mean for the daily averaged plasma parameters.
100
HP
80
60
40
Dcupcurrents(fA)
20
0
250 300 350 400
Day of 2018
450 500
Fig. 5 | Currents observed in the PLS D cup, which looks closest to the
VLISM flow. These are 15-point running averages from the spectra least
contaminated by noise. The currents decrease at the HP but do not go to
background levels, with a possible shock at day 418 and an increase in the
current level after day 435.
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gradual decrease in VR. We note that Krimigis et al.6
suggest a larger
region of decreased VR than the PLS measurements; why these differ-
ent instruments give different velocities is not yet understood.
The VLISM currents are variable with a possible shock observed
near Feb 22, 2019. The temperature of the VLISM is at the high end
of that expected, of order 30,000–50,000 K. This higher T suggests
either more compression of the plasma than predicted or heating by
reconnection. Variations of the currents observed during spacecraft
rolls provide convincing evidence that the PLS observes the VLISM
and may allow future determinations of the VLISM speed, density,
and temperature.
Methods
The Voyager PLS measures ion and electron currents with energy/charge of
10–5950 eV q−1
and is fully described by Bridge et al.9
. In the heliosheath, the
region of shocked solar wind between the termination shock and HP, data are
often observed in three or four of the cups. These spectra are fitted with convected
isotropic proton Maxwellian distributions using the full response function of the
instrument to determine the thermal proton velocity, density and temperature20
.
The average 1σ errors in the heliosheath are about 8% for radial speed, 25% for
density and 31% for the thermal speed21
. In the VLISM currents are only detected
in the sideways-looking D cup.
Data availability
Data from the Voyager Plasma experiment are available at http://web.mit.edu/
space/www/voyager.html
Received: 12 July 2019; Accepted: 27 September 2019;
Published: xx xx xxxx
References
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of interstellar plasma with Voyager 1. Science 341, 1489–1492 (2013).
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with the galaxy. Science 341, 144–147 (2013).
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region depleted of heliospheric ions. Science 341, 150–153 (2013).
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flow velocity for plasma in a heliosheath transition layer. Nature 474,
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124–127 (2012).
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Cosmic Ray Conf. Beijing 12, 29–32 (2012).
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25
1
40
100
80
60
50
40
20
10
5
30
30
20
10
5
Currents (fA)
15 20
Wth (km s–1
)
25 30
2
T (× 104
K)
3 5
20
15
VT(kms–1
)
10
5
Fig. 6 | Contours of currents in the 10–30 eV channel of the D cup. Data
are for the density 0.04 cm−3
measured by PWS as a function of VT and
the proton thermal speed (Wth) and T. The PLS currents at the times of the
PWS measurements varied from 35–50 fA, constraining the values of VT
and T to the shaded red and blue region. VT is probably under 15 km s−1
, so
the red region shows the preferred portion of VT and T parameter space.
Simulation
Simulation
12.2–14.5
12.2–14.5 eV
16.8–19.3 eV
10–12.2 eV
eV
40
50
30
20
Current(fA)
10
0
40
50
30
20
Current(fA)
10
0
0 10 20 30 40
Minute
Minute
50 60 70
0 20 40 60 80
Fig. 7 | Observations of plasma currents in selected high-energy
resolution M mode channels during the V2 rolls in 2019. Top: day 21.
Bottom: day 164. The simulated variation for the 12.2–14.5 eV channel for
VR, VT, VN = (0, 15, −10) km s−1
, N = 0.06 cm3
and T = 54,000 K is shown
by the dashed red line; simulations for other channels are qualitatively
similar. The two energy channels with the clearest response in each roll
are shown. The measured currents have noise; the variation shown is real,
but qualitative. The response of the cup during these rolls confirms that it
observes VLISM plasma; with more work on noise removal these data may
be used to determine the VLISM N, T and V.
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