The document presents new theorems regarding obtaining a four-dimensional de Sitter universe or non-de Sitter expanding universe from a static warped reduction on a closed compact manifold M. For de Sitter, it must violate the null energy condition. For non-de Sitter expansion, there exists a threshold wthresh such that for w < wthresh, there is a bound N(w) on the number of e-foldings that can occur before violating an energy condition, even if w is time-varying. The bounds depend on properties of M and number of extra dimensions. The new theorems engage more fully with the intrinsic curvature of M.
Talk given at Cambridge DAMTP on Friday, 20 June 2008. Describes recent work on understanding what is necessary to embed accelerating cosmology in higher-dimensional theory.
This paper constructs charged thin-shell wormholes in (2+1) dimensions by cutting and pasting charged BTZ black holes. The surface stresses are determined using the Darmois-Israel formalism. The stability of the shell is analyzed considering phantom energy and generalized Chaplygin gas equations of state. Linearized stability is also discussed around the static solution. Graphs show regions of stability for different parameters.
1) The rotational Doppler effect describes a change in the resonant frequency of a system due to relative rotation between the emitter and observer. (Beginning sentence)
2) For magnetic resonance systems like ESR, NMR, and FMR, the resonant frequency is sensitive to magnetic fields and will shift due to the rotational Doppler effect caused by particle rotation.
3) For free magnetic nanoparticles with rotation rates of around 100 kHz, the rotational Doppler shift of around 100 kHz is measurable and on the same order as the linewidth for ESR and FMR, allowing determination of the maximum position with 100 kHz accuracy.
This document summarizes research conducted at Universitat de Barcelona from 1990-2010 on quantum magnetism. It discusses several key topics: (1) quantum relaxation from 1990-1996, where relaxation rates were studied in thin films; (2) resonant spin tunneling from 1996-2010, where an external magnetic field causes energy level crossings allowing spin tunneling; (3) quantum magnetic deflagration, where a "flame front" of spin reversal propagates through a crystal; and (4) superradiance, where coherent emission of photons occurs as spins decay to the ground state. The rotational Doppler effect is also discussed as it applies to magnetic resonance techniques.
1. The document summarizes research on quantum effects in nanomagnetism, including single domain particles, molecular magnets, and superconductors.
2. It discusses quantum tunneling of magnetization in single domain particles and molecular magnets, where the spin can tunnel through an anisotropy barrier.
3. Resonant spin tunneling is observed in molecular magnets at certain magnetic field values where spin energy levels are degenerate, allowing quantum superposition and tunneling.
4. Other topics covered include quantum magnetic deflagration, superradiance, magnetic vortices, and quantum effects in type-I superconductors such as topological hysteresis and flux penetration/expulsion patterns
This document summarizes research on magnetic vortices in nanoscale disk structures. It discusses the magnetic equilibrium configuration of vortices, which consists of an out-of-plane vortex core approximately 10nm in size surrounded by an in-plane curling magnetization field. Applying an in-plane magnetic field causes the vortex core to displace perpendicularly. The document also examines the low-frequency gyrotropic mode of the vortex core and hysteresis loops corresponding to single domain to vortex transitions in an array of permalloy disks under varying magnetic fields and temperatures.
The document contains a collection of multiple choice questions related to earthquake engineering and vibration analysis. Some key topics covered include:
1. Types of vibrations such as free vibration, forced vibration, and damped vibration.
2. Parameters used to describe vibrations like logarithmic decrement, damping factor, and natural frequency.
3. Analysis of single degree of freedom vibrating systems including equations of motion.
4. Concepts like critical damping, resonance, and stiffness calculations for different structural configurations like springs in series and parallel.
Presentation at "Emerging problems in particle phenomenology" workshop held at CUNY on April 11, 2010. Has sensitivity of Jets+MET searches for 7 TeV LHC.
Talk given at Cambridge DAMTP on Friday, 20 June 2008. Describes recent work on understanding what is necessary to embed accelerating cosmology in higher-dimensional theory.
This paper constructs charged thin-shell wormholes in (2+1) dimensions by cutting and pasting charged BTZ black holes. The surface stresses are determined using the Darmois-Israel formalism. The stability of the shell is analyzed considering phantom energy and generalized Chaplygin gas equations of state. Linearized stability is also discussed around the static solution. Graphs show regions of stability for different parameters.
1) The rotational Doppler effect describes a change in the resonant frequency of a system due to relative rotation between the emitter and observer. (Beginning sentence)
2) For magnetic resonance systems like ESR, NMR, and FMR, the resonant frequency is sensitive to magnetic fields and will shift due to the rotational Doppler effect caused by particle rotation.
3) For free magnetic nanoparticles with rotation rates of around 100 kHz, the rotational Doppler shift of around 100 kHz is measurable and on the same order as the linewidth for ESR and FMR, allowing determination of the maximum position with 100 kHz accuracy.
This document summarizes research conducted at Universitat de Barcelona from 1990-2010 on quantum magnetism. It discusses several key topics: (1) quantum relaxation from 1990-1996, where relaxation rates were studied in thin films; (2) resonant spin tunneling from 1996-2010, where an external magnetic field causes energy level crossings allowing spin tunneling; (3) quantum magnetic deflagration, where a "flame front" of spin reversal propagates through a crystal; and (4) superradiance, where coherent emission of photons occurs as spins decay to the ground state. The rotational Doppler effect is also discussed as it applies to magnetic resonance techniques.
1. The document summarizes research on quantum effects in nanomagnetism, including single domain particles, molecular magnets, and superconductors.
2. It discusses quantum tunneling of magnetization in single domain particles and molecular magnets, where the spin can tunnel through an anisotropy barrier.
3. Resonant spin tunneling is observed in molecular magnets at certain magnetic field values where spin energy levels are degenerate, allowing quantum superposition and tunneling.
4. Other topics covered include quantum magnetic deflagration, superradiance, magnetic vortices, and quantum effects in type-I superconductors such as topological hysteresis and flux penetration/expulsion patterns
This document summarizes research on magnetic vortices in nanoscale disk structures. It discusses the magnetic equilibrium configuration of vortices, which consists of an out-of-plane vortex core approximately 10nm in size surrounded by an in-plane curling magnetization field. Applying an in-plane magnetic field causes the vortex core to displace perpendicularly. The document also examines the low-frequency gyrotropic mode of the vortex core and hysteresis loops corresponding to single domain to vortex transitions in an array of permalloy disks under varying magnetic fields and temperatures.
The document contains a collection of multiple choice questions related to earthquake engineering and vibration analysis. Some key topics covered include:
1. Types of vibrations such as free vibration, forced vibration, and damped vibration.
2. Parameters used to describe vibrations like logarithmic decrement, damping factor, and natural frequency.
3. Analysis of single degree of freedom vibrating systems including equations of motion.
4. Concepts like critical damping, resonance, and stiffness calculations for different structural configurations like springs in series and parallel.
Presentation at "Emerging problems in particle phenomenology" workshop held at CUNY on April 11, 2010. Has sensitivity of Jets+MET searches for 7 TeV LHC.
Soliton Stability of the 2D Nonlinear Schrödinger Equationsheilsn
The document discusses linear stability analysis of soliton solutions to the 2D nonlinear Schrodinger equation (NLS). It introduces NLS and its soliton solutions. It then performs a linear stability analysis by adding perturbations and deriving conditions for stability. This involves separating variables and examining the resulting spectral problem. In particular, it considers the high frequency limit and derives recursion relations to solve for the stability spectrum order-by-order in the perturbation parameter. Future work is mentioned to continue this analysis to higher orders.
1) Small particles in oscillatory flows with traveling waves tend to form ordered, low-dimensional structures known as particulate coherent structures (PAS).
2) The particles synchronize with the traveling waves, causing their individual motions to phase lock with the wave frequency and form the PAS.
3) Contrary to initial expectations, the mechanism behind PAS formation is quite simple - the inertial forces from the oscillatory flow and wave cause particles to synchronize with the wave, leading to the ordered structures.
This document discusses magnetic deflagration and detonation in nanomagnets and manganites. It summarizes previous work on magnetic avalanches in these materials and introduces the concept of quantum magnetic deflagration. Key findings include observing deflagration fronts propagating at resonant magnetic fields and a potential deflagration to detonation transition. The document also discusses using surface acoustic waves and high-frequency EPR to study spin dynamics, as well as observing magnetic deflagration and colossal resistivity changes in manganites.
A particle undergoes simple harmonic motion (SHM) if its acceleration is directly proportional to its displacement from a fixed point. For a particle undergoing SHM:
- Its acceleration is given by: = -n2x
- Its path is given by: x = a cos(nt) or x = a sin(nt), where a is the amplitude
- It has a period of T = 2π/n and a frequency of f = 1/T
The document then provides examples of applying these properties to determine if a particle is undergoing SHM and find its period and frequency.
Computation of the gravity gradient tensor due to topographic masses using te...Leonardo Uieda
The GOCE satellite mission has the objective of measuring the Earth's gravitational field with an unprecedented accuracy through the measurement of the gravity gradient tensor (GGT). One of the several applications of this new gravity data set is to study the geodynamics of the lithospheric plates, where the flat Earth approximation may not be ideal and the Earth's curvature should be taken into account. In such a case, the Earth could be modeled using tesseroids, also called spherical prisms, instead of the conventional rectangular prisms. The GGT due to a tesseroid is calculated using numerical integration methods, such as the Gauss-Legendre Quadrature (GLQ), as already proposed by Asgharzadeh et al. (2007) and Wild-Pfeiffer (2008). We present a computer program for the direct computation of the GGT caused by a tesseroid using the GLQ. The accuracy of this implementation was evaluated by comparing its results with the result of analytical formulas for the special case of a spherical cap with computation point located at one of the poles. The GGT due to the topographic masses of the Parana basin (SE Brazil) was estimated at 260 km altitude in an attempt to quantify this effect on the GOCE gravity data. The digital elevation model ETOPO1 (Amante and Eakins, 2009) between 40º W and 65º W and 10º S and 35º S, which includes the Paraná Basin, was used to generate a tesseroid model of the topography with grid spacing of 10' x 10' and a constant density of 2670 kg/m3. The largest amplitude observed was on the second vertical derivative component (-0.05 to 1.20 Eötvos) in regions of rough topography, such as that along the eastern Brazilian continental margins. These results indicate that the GGT due to topographic masses may have amplitudes of the same order of magnitude as the GGT due to density anomalies within the crust and mantle.
The document discusses the Kalman filter, an algorithm used to estimate unknown variables using measurements observed over time that contain noise. It provides three key points:
1) The Kalman filter is an optimal estimator that recursively infers parameters from indirect, noisy measurements by fusing predictions with new measurements.
2) It is conceptualized using an example of estimating a boat's position over time based on noisy sextant and GPS measurements.
3) The filter works by predicting the next state, taking a new measurement, and updating the estimate by weighing the prediction and measurement based on their uncertainties.
Un hombre de 49 años mató a martillazos a su ex pareja de 52 años en Barcelona, a pesar de que la mujer había denunciado al hombre en 54 ocasiones durante los últimos 10 años por malos tratos. Los vecinos sabían que el crimen ocurriría eventualmente, ya que el hombre había quebrantado una orden de alejamiento y amenazado repetidamente a la mujer, diciendo "Te voy a matar". El asesinato pone en duda la eficacia de las medidas preventivas contra los maltratadores.
http://inarocket.com
Learn BEM fundamentals as fast as possible. What is BEM (Block, element, modifier), BEM syntax, how it works with a real example, etc.
The document discusses how personalization and dynamic content are becoming increasingly important on websites. It notes that 52% of marketers see content personalization as critical and 75% of consumers like it when brands personalize their content. However, personalization can create issues for search engine optimization as dynamic URLs and content are more difficult for search engines to index than static pages. The document provides tips for SEOs to help address these personalization and SEO challenges, such as using static URLs when possible and submitting accurate sitemaps.
This document summarizes a study of CEO succession events among the largest 100 U.S. corporations between 2005-2015. The study analyzed executives who were passed over for the CEO role ("succession losers") and their subsequent careers. It found that 74% of passed over executives left their companies, with 30% eventually becoming CEOs elsewhere. However, companies led by succession losers saw average stock price declines of 13% over 3 years, compared to gains for companies whose CEO selections remained unchanged. The findings suggest that boards generally identify the most qualified CEO candidates, though differences between internal and external hires complicate comparisons.
How to Build a Dynamic Social Media PlanPost Planner
Stop guessing and wasting your time on networks and strategies that don’t work!
Join Rebekah Radice and Katie Lance to learn how to optimize your social networks, the best kept secrets for hot content, top time management tools, and much more!
Watch the replay here: bit.ly/socialmedia-plan
Lightning Talk #9: How UX and Data Storytelling Can Shape Policy by Mika Aldabaux singapore
How can we take UX and Data Storytelling out of the tech context and use them to change the way government behaves?
Showcasing the truth is the highest goal of data storytelling. Because the design of a chart can affect the interpretation of data in a major way, one must wield visual tools with care and deliberation. Using quantitative facts to evoke an emotional response is best achieved with the combination of UX and data storytelling.
Further discriminatory signature of inflationLaila A
These are the slides of the talk I gave on discriminating between models of inflation using space based gravitational wave detectors, at KEK in Tskuba University, Japan.
Polarization and charge transfer in classical molecular dynamicsJiahao Chen
1) Polarization and charge transfer are important effects usually neglected in classical molecular dynamics simulations.
2) The document presents a new charge transfer model, QTPIE, that corrects deficiencies in existing fluctuating charge models while maintaining similar computational cost.
3) Simulations of linear water chains using QTPIE demonstrate quantitative polarization trends and qualitative charge transfer trends that agree with ab initio results, showing an improvement over existing models.
The quantum bounce of neutrons has been observed at the peV energy level. An application of Ramsey's method of oscillating fields allows high-precision spectroscopy of neutrons bouncing on a surface. This technique could improve the sensitivity for testing neutron couplings to hypothetical short-range forces and influences on gravity. Future experiments aim to reach sensitivities needed to probe certain axion dark matter models and non-Newtonian gravity potentials.
This document is the introduction and instructions for a physics exam on multiple choice questions. It provides the exam format, which is 40 multiple choice questions to be answered on an answer sheet. It also lists various physics formulas and constants that may be useful for answering the questions. The exam covers topics in mechanics, waves, electricity, quantum physics and other areas of physics.
The document summarizes potential discoveries at the LHC beyond the Standard Model. It discusses:
1) Searches for new constituents like excited neutrinos that may appear as single particles produced via Z, W, or gamma decays.
2) Searches for new quark singlets with charges of -1/3 that could be discovered if pair produced and decaying to bosons and jets.
3) Searches for new up-type quark doublets that could be discovered if pair produced and decaying to W bosons and jets. The document outlines possible mass ranges and luminosities needed for discovery.
4) It notes how new quark discoveries could enhance the search for the Higgs boson
This document provides an overview of key concepts in superconductivity:
1. Superconductors are defined by having zero resistance below a critical temperature and being perfectly diamagnetic due to the Meissner effect.
2. However, superconductivity is limited by critical fields and currents. Most superconductors are also type II, allowing magnetic flux penetration through vortices.
3. The document outlines models of the superconducting state including the penetration depth, vortex lattices in type II superconductors, and effects of geometry and anisotropy on magnetic fields.
The document summarizes research on vibration energy harvesting under uncertainty. It discusses piezoelectric energy harvesting using cantilever beams and focuses on harvesting from single frequencies at resonance. It notes that most previous work assumes certain input but uncertainty exists in real environments. The document outlines sources of uncertainty in excitation and system parameters and presents linear and nonlinear models of piezoelectric energy harvesters. It transforms models into the frequency domain to analyze optimal harvester design under Gaussian excitation without an inductor.
The document discusses different diode circuits and models. It covers forward and reverse bias of diodes, diode characteristics, and diode applications such as voltage regulation circuits. Ideal diode models and piecewise linear diode models are presented as approximations to analyze circuits containing diodes. Load line analysis is demonstrated as a technique for solving diode circuits graphically based on the diode characteristic curve.
This document discusses various methods for detecting neutrinos. It is very difficult to detect neutrinos due to their weak interactions. The earliest detection was through inverse beta decay using a nuclear reactor. Later, the Sudbury Neutrino Observatory was able to detect neutrinos via different interactions in deuterium, providing evidence of neutrino flavor oscillations. Now, large detectors like IceCube are detecting high-energy neutrinos from astrophysical sources. Measuring the neutrino mass precisely remains challenging but various techniques using beta decay spectra provide upper limits.
This is a parallel presentation from SUSY09 in June 09 on Composite Inelastic Dark Matter. It proposes a model that reconciles various direct detection dark matter experiments.
Soliton Stability of the 2D Nonlinear Schrödinger Equationsheilsn
The document discusses linear stability analysis of soliton solutions to the 2D nonlinear Schrodinger equation (NLS). It introduces NLS and its soliton solutions. It then performs a linear stability analysis by adding perturbations and deriving conditions for stability. This involves separating variables and examining the resulting spectral problem. In particular, it considers the high frequency limit and derives recursion relations to solve for the stability spectrum order-by-order in the perturbation parameter. Future work is mentioned to continue this analysis to higher orders.
1) Small particles in oscillatory flows with traveling waves tend to form ordered, low-dimensional structures known as particulate coherent structures (PAS).
2) The particles synchronize with the traveling waves, causing their individual motions to phase lock with the wave frequency and form the PAS.
3) Contrary to initial expectations, the mechanism behind PAS formation is quite simple - the inertial forces from the oscillatory flow and wave cause particles to synchronize with the wave, leading to the ordered structures.
This document discusses magnetic deflagration and detonation in nanomagnets and manganites. It summarizes previous work on magnetic avalanches in these materials and introduces the concept of quantum magnetic deflagration. Key findings include observing deflagration fronts propagating at resonant magnetic fields and a potential deflagration to detonation transition. The document also discusses using surface acoustic waves and high-frequency EPR to study spin dynamics, as well as observing magnetic deflagration and colossal resistivity changes in manganites.
A particle undergoes simple harmonic motion (SHM) if its acceleration is directly proportional to its displacement from a fixed point. For a particle undergoing SHM:
- Its acceleration is given by: = -n2x
- Its path is given by: x = a cos(nt) or x = a sin(nt), where a is the amplitude
- It has a period of T = 2π/n and a frequency of f = 1/T
The document then provides examples of applying these properties to determine if a particle is undergoing SHM and find its period and frequency.
Computation of the gravity gradient tensor due to topographic masses using te...Leonardo Uieda
The GOCE satellite mission has the objective of measuring the Earth's gravitational field with an unprecedented accuracy through the measurement of the gravity gradient tensor (GGT). One of the several applications of this new gravity data set is to study the geodynamics of the lithospheric plates, where the flat Earth approximation may not be ideal and the Earth's curvature should be taken into account. In such a case, the Earth could be modeled using tesseroids, also called spherical prisms, instead of the conventional rectangular prisms. The GGT due to a tesseroid is calculated using numerical integration methods, such as the Gauss-Legendre Quadrature (GLQ), as already proposed by Asgharzadeh et al. (2007) and Wild-Pfeiffer (2008). We present a computer program for the direct computation of the GGT caused by a tesseroid using the GLQ. The accuracy of this implementation was evaluated by comparing its results with the result of analytical formulas for the special case of a spherical cap with computation point located at one of the poles. The GGT due to the topographic masses of the Parana basin (SE Brazil) was estimated at 260 km altitude in an attempt to quantify this effect on the GOCE gravity data. The digital elevation model ETOPO1 (Amante and Eakins, 2009) between 40º W and 65º W and 10º S and 35º S, which includes the Paraná Basin, was used to generate a tesseroid model of the topography with grid spacing of 10' x 10' and a constant density of 2670 kg/m3. The largest amplitude observed was on the second vertical derivative component (-0.05 to 1.20 Eötvos) in regions of rough topography, such as that along the eastern Brazilian continental margins. These results indicate that the GGT due to topographic masses may have amplitudes of the same order of magnitude as the GGT due to density anomalies within the crust and mantle.
The document discusses the Kalman filter, an algorithm used to estimate unknown variables using measurements observed over time that contain noise. It provides three key points:
1) The Kalman filter is an optimal estimator that recursively infers parameters from indirect, noisy measurements by fusing predictions with new measurements.
2) It is conceptualized using an example of estimating a boat's position over time based on noisy sextant and GPS measurements.
3) The filter works by predicting the next state, taking a new measurement, and updating the estimate by weighing the prediction and measurement based on their uncertainties.
Un hombre de 49 años mató a martillazos a su ex pareja de 52 años en Barcelona, a pesar de que la mujer había denunciado al hombre en 54 ocasiones durante los últimos 10 años por malos tratos. Los vecinos sabían que el crimen ocurriría eventualmente, ya que el hombre había quebrantado una orden de alejamiento y amenazado repetidamente a la mujer, diciendo "Te voy a matar". El asesinato pone en duda la eficacia de las medidas preventivas contra los maltratadores.
http://inarocket.com
Learn BEM fundamentals as fast as possible. What is BEM (Block, element, modifier), BEM syntax, how it works with a real example, etc.
The document discusses how personalization and dynamic content are becoming increasingly important on websites. It notes that 52% of marketers see content personalization as critical and 75% of consumers like it when brands personalize their content. However, personalization can create issues for search engine optimization as dynamic URLs and content are more difficult for search engines to index than static pages. The document provides tips for SEOs to help address these personalization and SEO challenges, such as using static URLs when possible and submitting accurate sitemaps.
This document summarizes a study of CEO succession events among the largest 100 U.S. corporations between 2005-2015. The study analyzed executives who were passed over for the CEO role ("succession losers") and their subsequent careers. It found that 74% of passed over executives left their companies, with 30% eventually becoming CEOs elsewhere. However, companies led by succession losers saw average stock price declines of 13% over 3 years, compared to gains for companies whose CEO selections remained unchanged. The findings suggest that boards generally identify the most qualified CEO candidates, though differences between internal and external hires complicate comparisons.
How to Build a Dynamic Social Media PlanPost Planner
Stop guessing and wasting your time on networks and strategies that don’t work!
Join Rebekah Radice and Katie Lance to learn how to optimize your social networks, the best kept secrets for hot content, top time management tools, and much more!
Watch the replay here: bit.ly/socialmedia-plan
Lightning Talk #9: How UX and Data Storytelling Can Shape Policy by Mika Aldabaux singapore
How can we take UX and Data Storytelling out of the tech context and use them to change the way government behaves?
Showcasing the truth is the highest goal of data storytelling. Because the design of a chart can affect the interpretation of data in a major way, one must wield visual tools with care and deliberation. Using quantitative facts to evoke an emotional response is best achieved with the combination of UX and data storytelling.
Further discriminatory signature of inflationLaila A
These are the slides of the talk I gave on discriminating between models of inflation using space based gravitational wave detectors, at KEK in Tskuba University, Japan.
Polarization and charge transfer in classical molecular dynamicsJiahao Chen
1) Polarization and charge transfer are important effects usually neglected in classical molecular dynamics simulations.
2) The document presents a new charge transfer model, QTPIE, that corrects deficiencies in existing fluctuating charge models while maintaining similar computational cost.
3) Simulations of linear water chains using QTPIE demonstrate quantitative polarization trends and qualitative charge transfer trends that agree with ab initio results, showing an improvement over existing models.
The quantum bounce of neutrons has been observed at the peV energy level. An application of Ramsey's method of oscillating fields allows high-precision spectroscopy of neutrons bouncing on a surface. This technique could improve the sensitivity for testing neutron couplings to hypothetical short-range forces and influences on gravity. Future experiments aim to reach sensitivities needed to probe certain axion dark matter models and non-Newtonian gravity potentials.
This document is the introduction and instructions for a physics exam on multiple choice questions. It provides the exam format, which is 40 multiple choice questions to be answered on an answer sheet. It also lists various physics formulas and constants that may be useful for answering the questions. The exam covers topics in mechanics, waves, electricity, quantum physics and other areas of physics.
The document summarizes potential discoveries at the LHC beyond the Standard Model. It discusses:
1) Searches for new constituents like excited neutrinos that may appear as single particles produced via Z, W, or gamma decays.
2) Searches for new quark singlets with charges of -1/3 that could be discovered if pair produced and decaying to bosons and jets.
3) Searches for new up-type quark doublets that could be discovered if pair produced and decaying to W bosons and jets. The document outlines possible mass ranges and luminosities needed for discovery.
4) It notes how new quark discoveries could enhance the search for the Higgs boson
This document provides an overview of key concepts in superconductivity:
1. Superconductors are defined by having zero resistance below a critical temperature and being perfectly diamagnetic due to the Meissner effect.
2. However, superconductivity is limited by critical fields and currents. Most superconductors are also type II, allowing magnetic flux penetration through vortices.
3. The document outlines models of the superconducting state including the penetration depth, vortex lattices in type II superconductors, and effects of geometry and anisotropy on magnetic fields.
The document summarizes research on vibration energy harvesting under uncertainty. It discusses piezoelectric energy harvesting using cantilever beams and focuses on harvesting from single frequencies at resonance. It notes that most previous work assumes certain input but uncertainty exists in real environments. The document outlines sources of uncertainty in excitation and system parameters and presents linear and nonlinear models of piezoelectric energy harvesters. It transforms models into the frequency domain to analyze optimal harvester design under Gaussian excitation without an inductor.
The document discusses different diode circuits and models. It covers forward and reverse bias of diodes, diode characteristics, and diode applications such as voltage regulation circuits. Ideal diode models and piecewise linear diode models are presented as approximations to analyze circuits containing diodes. Load line analysis is demonstrated as a technique for solving diode circuits graphically based on the diode characteristic curve.
This document discusses various methods for detecting neutrinos. It is very difficult to detect neutrinos due to their weak interactions. The earliest detection was through inverse beta decay using a nuclear reactor. Later, the Sudbury Neutrino Observatory was able to detect neutrinos via different interactions in deuterium, providing evidence of neutrino flavor oscillations. Now, large detectors like IceCube are detecting high-energy neutrinos from astrophysical sources. Measuring the neutrino mass precisely remains challenging but various techniques using beta decay spectra provide upper limits.
This is a parallel presentation from SUSY09 in June 09 on Composite Inelastic Dark Matter. It proposes a model that reconciles various direct detection dark matter experiments.
The document discusses key topics in microwave engineering including:
1. Maxwell's equations which describe the fundamentals of electromagnetics.
2. Explanations of important concepts like electric and magnetic fields, vectors, divergence, curl and boundary conditions.
3. An overview of industries utilizing RF components and analysis of the RF components market including development trends, major companies and factors changing the industry.
1) The document discusses the governing equations for fluid dynamics, which are derived from conservation laws of physics, including conservation of mass, momentum, and energy.
2) These equations can be derived using either a Lagrangian description that follows fluid particles, or an Eulerian description that considers properties at fixed points in space and time.
3) Key equations derived include the continuity equation, momentum equations, and energy equation, which relate the rate of change of properties like density, momentum, and energy to surface and body forces.
2018SOE07-Kim-Computation of Added resistance of ships by using a frequency-d...SahilJawa3
This document summarizes research on using a frequency-domain Rankine panel method to compute the added resistance of ships in waves. It presents the background and motivation for accurately predicting added resistance. It reviews previous related work using frequency-domain and time-domain Rankine panel methods. It then describes the boundary value problem, basis potential evaluation, frequency-domain formulation, and higher-order B-spline panel numerical method used in the presented research. The research aims to efficiently and accurately predict added resistance for ship design and operation under IMO greenhouse gas emission regulations.
This document discusses magnetic resonance imaging (MRI) principles and techniques. It explains that MRI utilizes the magnetic spin property of hydrogen protons to produce images. It describes how tissues have different relaxation times on T1-weighted and T2-weighted MRI sequences. Key sequences discussed include FLAIR, STIR, DWI and ADC mapping which provide contrast between different tissues. The document summarizes the clinical applications and benefits of these various MRI sequences.
The document summarizes key developments in nuclear magnetic resonance (NMR) spectroscopy from its theoretical prediction in the 1930s to modern applications. It describes Pauli's prediction of nuclear spin in 1926, the detection of nuclear magnetic moments in the 1930s-1940s, and the awarding of Nobel Prizes to scientists who developed NMR techniques. It then discusses chemical shifts, spin properties of different nuclei, interactions such as Zeeman and J-coupling that provide structural information, and experimental aspects like magic angle spinning.
This document summarizes key concepts in symmetry in physics. It discusses that symmetries describe transformations where objects remain the same, like rotations or translations in space and time. Symmetries lead to conservation laws through Noether's theorem. Gauge theories like quantum electrodynamics are symmetric under local transformations of particle properties. The Standard Model combines three gauge symmetries. Spin is a fundamental property of particles related to intrinsic angular momentum and rotations in quantum spaces. The spin-statistics theorem relates particle spin to their wavefunction symmetry and statistics.
Instantons and Chern-Simons Terms in AdS4/CFT3: Gravity on the Brane?Sebastian De Haro
1) The document discusses instanton solutions in AdS4/CFT3 duality that probe non-conformal vacuums.
2) It constructs an explicit instanton solution for a conformally coupled scalar field with a quartic interaction in an AdS4 background.
3) Holographically, this instanton describes the decay of the AdS4 vacuum via tunneling, mediated by dressing with a non-zero scalar field. The decay rate is computed.
This document discusses developing a pressure balance watt balance to redefine the kilogram in terms of the Planck constant. It would use two pressure balances in weighing mode for force comparison and oscillating coil motion in dynamic mode. Research is underway to improve pressure balance performance, measure coil motion and induced voltage, design magnets, and address ground vibration issues. The goal is to have an operational pressure balance watt balance by mid-2013 to contribute results in advance of a 2014 international dataset compilation.
This document summarizes a presentation on new physics scenarios beyond the Standard Model. It begins with defining what is meant by a "new physics scenario" and discusses four main motivations for considering new physics: experiments not matching theoretical predictions, unnatural parameters, reducing the number of parameters, and exploring what is possible. The document then outlines some organizing principles for new physics scenarios, including chirality, anomaly cancellation, flavor symmetries, gauge coupling unification, and effective field theory. Specific new physics scenarios discussed include supersymmetry, extra dimensions, strong dynamics, and others.
Electron dynamics in a biased quantum well dosKevinrl
This document discusses how applying an electric field to a quantum well redistributes the density of states. It presents the methodology for solving Schrodinger's equation for a biased quantum well to determine the 1D and 3D density of states. The 1D density of states spreads around the energy level and the normally step-like 3D density of states smooths out and approaches the bulk density of states as the applied electric field increases. This redistribution of states changes characteristics like thermionic emission and carrier scattering in quantum well devices.
Similar to New no-go theorems and the costs of cosmic acceleration (20)
HCL Notes and Domino License Cost Reduction in the World of DLAUpanagenda
Webinar Recording: https://www.panagenda.com/webinars/hcl-notes-and-domino-license-cost-reduction-in-the-world-of-dlau/
The introduction of DLAU and the CCB & CCX licensing model caused quite a stir in the HCL community. As a Notes and Domino customer, you may have faced challenges with unexpected user counts and license costs. You probably have questions on how this new licensing approach works and how to benefit from it. Most importantly, you likely have budget constraints and want to save money where possible. Don’t worry, we can help with all of this!
We’ll show you how to fix common misconfigurations that cause higher-than-expected user counts, and how to identify accounts which you can deactivate to save money. There are also frequent patterns that can cause unnecessary cost, like using a person document instead of a mail-in for shared mailboxes. We’ll provide examples and solutions for those as well. And naturally we’ll explain the new licensing model.
Join HCL Ambassador Marc Thomas in this webinar with a special guest appearance from Franz Walder. It will give you the tools and know-how to stay on top of what is going on with Domino licensing. You will be able lower your cost through an optimized configuration and keep it low going forward.
These topics will be covered
- Reducing license cost by finding and fixing misconfigurations and superfluous accounts
- How do CCB and CCX licenses really work?
- Understanding the DLAU tool and how to best utilize it
- Tips for common problem areas, like team mailboxes, functional/test users, etc
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4. Two data sets
ä>0 ä > 0 (?)
Late universe Early universe
(dark energy) (inflation?)
5. Old no-go theorems
Theorem (Gibbons ’84, Maldacena and Nunez ‘01)
To obtain a four-dimensional de Sitter universe from a static
warped reduction on closed compact manifold M, one must
violate the Strong Energy Condition (SEC).
6. Old no-go theorems
Theorem (Gibbons ’84, Maldacena and Nunez ‘01)
To obtain a four-dimensional de Sitter universe from a static
warped reduction on closed compact manifold M, one must
violate the Strong Energy Condition (SEC).
Evasive maneuvers
(a) Time dependent M
(b) Non-de Sitter expansion
(c) Transient de Sitter
(d) Accept SEC violation **
(e) Non-compact M (finite GN?)
** not always an option, depending on the theory
7. Old no-go theorems
Theorem (Gibbons ’84, Maldacena and Nunez ‘01)
To obtain a four-dimensional de Sitter universe from a static
warped reduction on closed compact manifold M, one must
violate the Strong Energy Condition (SEC).
Evasive maneuvers New improvements
(a) Time dependent M (1) Weaken energy condition
(b) Non-de Sitter expansion (2) Include non-de Sitter (w>-1)
(c) Transient de Sitter (3) Treat time-dependent M
(d) Accept SEC violation **
(e) Non-compact M (finite GN?)
** not always an option, depending on the theory
8. Some energy conditions
Null TMNnMnN ≥ 0 RMNtMtN ≥ 0 Strong
P P “geodesics
“gravity
is stable” ρ ρ converge” ≈
“gravity is
ρ
attractive”
Weak TMNtMtN ≥ 0 TMNtM not S.L. Dominant
P
“energy density P “subluminal
positive for all ρ ρ phase velocity”
observers”
ρ≥0 ρ ≥ |P |
ρ+P ≥0
9. Some energy conditions
Null TMNnMnN ≥ 0 RMNtMtN ≥ 0 Strong
P P “geodesics
“gravity
is stable” ρ ρ converge” ≈
“gravity is
attractive”
10. Some energy conditions
Null TMNnMnN ≥ 0 RMNtMtN ≥ 0 Strong
P P “geodesics
“gravity
is stable” ρ ρ converge” ≈
“gravity is
attractive”
•ρ+P≥0 • ρ + P ≥ 0 and ρ + 3P ≥ 0
• Two-derivative actions with positive • Scalars with V(φ) ≤ 0
definite kinetic terms, any V(φ) • ... classical 11D SUGRA + others
• D-branes & positive tension objects • anti-de Sitter Λ<0
• Implied by all other energy conditions • dust and radiation Satisfied by
• Casimir energy (...unless averaged) • Scalars with V (φ) >0 anywhere
• Negative tension (orientifold planes) • de Sitter Λ>0
• ghost condensates • D-branes
Violated by
11. The Null Energy Condition
...keeps us safe from... Causality violations
Instabilities & other pathologies
12. The Null Energy Condition
...keeps us safe from... Causality violations
Superluminal travel, “warp drives,”
traversable wormholes, time machines,
CTCs, chronology (non-)protection ...
Morris, Thorne Am. J. Phys. 56 (1988) 395 ; Visser, Kar, Dadhich Phys. Rev.
Lett. 90 (2003) 201102 ; Alcubierre Class. Quant. Grav. 11 (1994) L73 ;
Krasnikov Phys. Rev. D 57 (1998) 4760 ; Morris, Thorne, Yurtsever Phys.
Rev. Lett. 61 (1988) 1446 ; Hawking Phys. Rev. D 46 (1992) 603
Instabilities & other pathologies
13. The Null Energy Condition
...keeps us safe from... Causality violations
Superluminal travel, “warp drives,”
traversable wormholes, time machines,
CTCs, chronology (non-)protection ...
Morris, Thorne Am. J. Phys. 56 (1988) 395 ; Visser, Kar, Dadhich Phys. Rev.
Lett. 90 (2003) 201102 ; Alcubierre Class. Quant. Grav. 11 (1994) L73 ;
Krasnikov Phys. Rev. D 57 (1998) 4760 ; Morris, Thorne, Yurtsever Phys.
Rev. Lett. 61 (1988) 1446 ; Hawking Phys. Rev. D 46 (1992) 603
Instabilities & other pathologies
Classical: Big Rips, Big Bounces, gradient
instabilities ...
Quantum: unitarity violation, rapid
vacuum decay, perpetuum mobile ...
Cline, Jeon, Moore Phys. Rev. D 70 (2004) 043543 ; Hsu, Jenkins, Wise
Phys. Lett. B 597 (2004) 270 ; Dubovsky, Gregoire, Nicolis, Rattazzi JHEP
0603 (2006) 025 ; Buniy, Hsu, Murray Phys. Rev. D 74 (2006) 063518 ;
Caldwell Phys. Lett. B 545 (2002) 23 ; Caldwell, Kamionkowski, Weinberg
Phys. Rev. Lett. 91 (2003) 071301, Arkani-Hamed, Dubovsky, Nicolis,
Trincherini, Villadoro JHEP 05 (2007) 055 ; Dubovsky, Sibiryakov Phys.
Lett. B 638 (2006) 509
14. Types of new theorems
de Sitter theorems
Non-de Sitter (w>-1) theorems
15. Types of new theorems
de Sitter theorems
• concerned with eternal de Sitter expansion
• must violate null energy condition under broad circumstances
• previous theorems used R00 because it does not involve the intrinsic
curvature R of M. To prove the new theorems, you look at the other
components and engage with the complexity of dealing with R.
Non-de Sitter (w>-1) theorems
16. Types of new theorems
de Sitter theorems
• concerned with eternal de Sitter expansion
• must violate null energy condition under broad circumstances
• previous theorems used R00 because it does not involve the intrinsic
curvature R of M. To prove the new theorems, you look at the other
components and engage with the complexity of dealing with R.
Non-de Sitter (w>-1) theorems
• For each number k of extra dimensions**
• There exists a threshold wthresh
• For w < wthresh there is a bound N(w) on the number of e-foldings
• Constant w: undergoing N > N(w) e-folds violates an energy condition.
• Varying w (1): for any w(t) the bound N[w(t)] obtained by quadrature.
• Varying w (2): if w < w✻ then N[w(t)] < N(w✻).
** depends on other properties of M, to be described
17. Types of new theorems
de Sitter theorems
• concerned with eternal de Sitter expansion
• must violate null energy condition under broad circumstances
• previous theorems used R00 because it does not involve the intrinsic
curvature R of M. To prove the new theorems, you look at the other
components and engage with the complexity of dealing with R.
Non-de Sitter (w>-1) theorems
• For each number k of extra dimensions**
• There exists a threshold wthresh
• For w < wthresh there is a bound N(w) on the number of e-foldings
• Constant w: undergoing N > N(w) e-folds violates an energy condition.
• Varying w (1): for any w(t) the bound N[w(t)] obtained by quadrature.
• Varying w (2): if w < w✻ then N[w(t)] < N(w✻).
** depends on other properties of M, to be described
18. Types of new theorems
de Sitter theorems
• concerned with eternal de Sitter expansion
• must violate null energy condition under broad circumstances
• previous theorems used R00 because it does not involve the intrinsic
curvature R of M. To prove the new theorems, you look at the other
components and engage with the complexity of dealing with R.
Non-de Sitter (w>-1) theorems
• For each number k of extra dimensions**
• There exists a threshold wthresh
• For w < wthresh there is a bound N(w) on the number of e-foldings
• Constant w: undergoing N > N(w) e-folds violates an energy condition.
• Varying w (1): for any w(t) the bound N[w(t)] obtained by quadrature.
• Varying w (2): if w < w✻ then N[w(t)] < N(w✻).
** depends on other properties of M, to be described
19. Types of new theorems
de Sitter theorems
• concerned with eternal de Sitter expansion
• must violate null energy condition under broad circumstances
• previous theorems used R00 because it does not involve the intrinsic
curvature R of M. To prove the new theorems, you look at the other
components and engage with the complexity of dealing with R.
Non-de Sitter (w>-1) theorems
• For each number k of extra dimensions**
• There exists a threshold wthresh
• For w < wthresh there is a bound N(w) on the number of e-foldings
• Constant w: undergoing N > N(w) e-folds violates an energy condition.
• Varying w (1): for any w(t) the bound N[w(t)] obtained by quadrature.
• Varying w (2): if w < w✻ then N[w(t)] < N(w✻).
** depends on other properties of M, to be described
20. Types of M
Curvature-free Curved
Intrinsic Ricci scalar R
R≠0 somewhere on M
vanishes everywhere on M
• One-dimensional (KK & RS) • Manifolds with non-Abelian
• Tori -- continuous isometries **
• realised by periodic ... includes models which obtain 4D
identification of Rn gauge symmetries by KK reduction
• with R ≥ 0 everywhere
• Special holonomy -- • Rugby-ball SLED
• Sp(n)
• Spin(7) ** We only know these cannot be Ricci-
• SU(n) (Calabi-Yau) flat, which is a stronger condition than
• G2 (M theory) “curvature-free.”
21. Types of M
Curvature-free Curved
Intrinsic Ricci scalar R
R≠0 somewhere on M
vanishes everywhere on M
• One-dimensional (KK & RS) • Manifolds with non-Abelian
• Tori -- continuous isometries **
• realised by periodic ... includes models which obtain 4D
identification of Rn gauge symmetries by KK reduction
• with R ≥ 0 everywhere
• Special holonomy -- • Rugby-ball SLED
• Sp(n)
• Spin(7) ** We only know these cannot be Ricci-
• SU(n) (Calabi-Yau) flat, which is a stronger condition than
• G2 (M theory) “curvature-free.”
22. Types of M
Curvature-free Curved
Intrinsic Ricci scalar R
R≠0 somewhere on M
vanishes everywhere on M
• One-dimensional (KK & RS) • Manifolds with non-Abelian
• Tori -- continuous isometries **
• realised by periodic ... includes models which obtain 4D
identification of Rn gauge symmetries by KK reduction
• with R ≥ 0 everywhere
• Special holonomy -- • Rugby-ball SLED
• Sp(n)
• Spin(7) ** We only know these cannot be Ricci-
• SU(n) (Calabi-Yau) flat, which is a stronger condition than
• G2 (M theory) “curvature-free.”
23. Comparison with previous theorems
curvature-free curved
Strong
(Gibbons et. al.)
de Sitter
w > -1
24. Comparison with previous theorems
curvature-free curved
Strong
(Gibbons et. al.)
de Sitter NEW NEW
Null Null*
*bounded avg. condition
w > -1
25. Comparison with previous theorems
curvature-free curved
Strong
(Gibbons et. al.)
de Sitter NEW NEW
Null Null*
*bounded avg. condition
NEW NEW
w > -1 Null Strong
(transient) (transient)
26. A simple example (I)
Ricci-flat extra dimensions with breathing-mode dynamics
2c
ds2
4+k = A(η)
2
−dη +
2
dx2
3 + exp ψ(η) ds2
k
k
27. A simple example (I)
Ricci-flat extra dimensions with breathing-mode dynamics
2c
ds2
4+k = A(η)2
−dη +
2
dx2
3 + exp ψ(η) ds2
k
k
Conversion to 4D Einstein frame
2k
c= a(η) = ecψ/2 A(η)
k+2
28. A simple example (I)
Ricci-flat extra dimensions with breathing-mode dynamics
2c
ds2
4+k = A(η)2
−dη +
2
dx2
3 + exp ψ(η) ds2
k
k
Conversion to 4D Einstein frame
2k
c= a(η) = ecψ/2 A(η)
k+2
Apply 4D Friedmann equations
2
1+w dψ
a(η) ∼ η 2/(1+3w) ρ+P = H =
2
3 dη
29. A simple example (I)
Ricci-flat extra dimensions with breathing-mode dynamics
2c
ds2
4+k = A(η)2
−dη +
2
dx2
3 + exp ψ(η) ds2
k
k
Conversion to 4D Einstein frame
2k
c= a(η) = ecψ/2 A(η)
k+2
Apply 4D Friedmann equations
2
1+w dψ
a(η) ∼ η 2/(1+3w) ρ+P = H =
2
3 dη
Yields η-dependence of ψ and A.
1+w
ψ(η) = ± ln η 6 + ψ0
1 + 3w
30. A simple example (II)
Reconstruct (4+k)D metric and use Einstein
equations to compute stress-energy tensor
1+w √
ψ(η) = ± ln η 6 + ψ0 V (ψ) = V0 e 3(1+w)ψ
1 + 3w
31. A simple example (II)
Reconstruct (4+k)D metric and use Einstein
equations to compute stress-energy tensor
w
NEC OK NEC OK
TMN nMnN
P = -2 ρ
NEC violated NEC violated
w k
1+w √
ψ(η) = ± ln η 6 + ψ0 V (ψ) = V0 e 3(1+w)ψ
1 + 3w
32. A simple example (II)
Lesson: potentials that look perfectly reasonable in 4D
require exotic physics in higher-dimensional context.
Reconstruct (4+k)D metric and use Einstein
equations to compute stress-energy tensor
w
NEC OK NEC OK
TMN nMnN
P = -2 ρ
NEC violated NEC violated
w k
1+w √
ψ(η) = ± ln η 6 + ψ0 V (ψ) = V0 e 3(1+w)ψ
1 + 3w
33. Assumptions
• M closed and compact, or a quotient of c.c. M/G
• Higher-dimensional action has Einstein-Hilbert form
...includes g(φ)R and F(R) models
• Arbitrary other matter fields present
• All four-dimensional statements refer to the Einstein
frame metric and its associated cosmology.
Denote by claim proven in the “long” paper 0802.3214
35. Three tools...
1. Decomposition of metric time derivative.
(Proxy for KK scalars and/or metric moduli)
36. Three tools...
1. Decomposition of metric time derivative.
(Proxy for KK scalars and/or metric moduli)
37. Three tools...
1. Decomposition of metric time derivative.
(Proxy for KK scalars and/or metric moduli)
2. One-parameter family of averages on the manifold
38. Three tools...
1. Decomposition of metric time derivative.
(Proxy for KK scalars and/or metric moduli)
2. One-parameter family of averages on the manifold
3. “NEC probes.” If negative the NEC must be violated.
39. Three tools...
1. Decomposition of metric time derivative.
(Proxy for KK scalars and/or metric moduli)
2. One-parameter family of averages on the manifold
3. “NEC probes.” If negative the NEC must be violated.
40. ...many challenges
• non-uniqueness of KK inversion
• (equiv) 4D theory gives only nonlocal information on M
• lack of explicit moduli space description
• apparent ghosts from conformal deformations of M
• “arbitrary” warp factor and deformations of M
• nature of the physics that causes acceleration?
• ...
41. ...many challenges
• non-uniqueness of KK inversion
• (equiv) 4D theory gives only nonlocal information on M
• lack of explicit moduli space description
• apparent ghosts from conformal deformations of M
• “arbitrary” warp factor and deformations of M
• nature of the physics that causes acceleration?
• ...
44. Averages of NEC probes
1. Metric deformations
enter with negative sign
45. Averages of NEC probes
1. Metric deformations
enter with negative sign
2. Negative
definite
46. Averages of NEC probes
1. Metric deformations
enter with negative sign
2. Negative 3. Coefficients depend on
definite averaging parameter A.
47. Averages of NEC probes
1. Metric deformations
enter with negative sign
2. Negative 3. Coefficients depend on
definite averaging parameter A.
4. “Arbitrary” warp function
enters the NEC condition
48. Averages of NEC probes
1. Metric deformations
enter with negative sign
2. Negative 3. Coefficients depend on
definite averaging parameter A.
4. “Arbitrary” warp function
enters the NEC condition
5. kN depends on dξ/dt
49. The v-equation
Minimax strategy -- choose A to minimise
the maximum number of e-foldings
50. The v-equation
Minimax strategy -- choose A to minimise
the maximum number of e-foldings
51. The v-equation
Minimax strategy -- choose A to minimise
the maximum number of e-foldings
“Optimising” A: value of A for which all coefficients are positive**
52. The v-equation
Minimax strategy -- choose A to minimise
the maximum number of e-foldings
“Optimising” A: value of A for which all coefficients are positive**
An optimising A always exists.
53. The v-equation
Minimax strategy -- choose A to minimise
the maximum number of e-foldings
“Optimising” A: value of A for which all coefficients are positive**
An optimising A always exists.
Optimal solution: saturates the inequalities 3N and kN. Any
other solution has fewer e-foldings consistent with the NEC.
54. The v-equation
Minimax strategy -- choose A to minimise
the maximum number of e-foldings
“Optimising” A: value of A for which all coefficients are positive**
An optimising A always exists.
Optimal solution: saturates the inequalities 3N and kN. Any
other solution has fewer e-foldings consistent with the NEC.
This gives a differential equation and boundary
conditions obeyed by the optimal solution
61. e-folds (II)
w
nS ≥ 0.90 w ≤ -0.97
w
nS ≥ 0.90 w ≤ -0.97
number of extra dimensions
62. Conclusions
• de Sitter case: weakened the energy condition to
the NEC in a variety of cases
• w > -1 case: constrained the number of allowed e-
foldings of accelerated expansion consistent with
energy conditions
• Instead of constructing examples of models, we
make statements about broad classes.
• Challenge -- many models with acceleration must
violate energy conditions consistently to be viable.