The Compton effect is the result of a high-energy photon colliding with a target, which releases loosely bound electrons from the outer shell of the atom or molecule .
The Compton effect is the result of a high-energy photon colliding with a target, which releases loosely bound electrons from the outer shell of the atom or molecule .
Laser is very important technological device these days.There is a use of laser in almost every field of science and technology. It also gives it's application in medicines also.
This presentation shows how it works and what is the mechanism behind this laser phenomenon. Here it is explained from atom theory to application.
Very good explanation with photographs.
(A) By active media
Solid state laser - crystal, or glass, doped with impurities, e.g. ruby laser, Ti:sapphire laser, semiconductor laser.
Gas laser - e.g. He-Ne laser, Ar+ laser, CO2 laser, N2 laser, HCN laser.
Dye laser - active medium: dye molecules in liquid solvent (sometimes in solids also).
(B) By mode of operation
CW
Pulsed
(C) By pumping and laser levels
3-level laser
4-level laser
Introduction to semiconductor lasers, and its working. construction of semiconductor laser, Ga As laser, and construction, achievement of population inversion, pumping.
Photonic crystals are periodic dielectric structures that have a band gap that forbids propagation of a certain frequency range of light. This property enables one to control light with amazing facility and produce effects that are impossible with conventional optics.Photonic crystals can be fabricated for one, two, or three dimensions. One-dimensional photonic crystals can be made of layers deposited or stuck together. Two-dimensional ones can be made by photolithography, or by drilling holes in a suitable substrate. Fabrication methods for three-dimensional ones include drilling under different angles, stacking multiple 2-D layers on top of each other, direct laser writing, or, for example, instigating self-assembly of spheres in a matrix and dissolving the spheres
Laser is very important technological device these days.There is a use of laser in almost every field of science and technology. It also gives it's application in medicines also.
This presentation shows how it works and what is the mechanism behind this laser phenomenon. Here it is explained from atom theory to application.
Very good explanation with photographs.
(A) By active media
Solid state laser - crystal, or glass, doped with impurities, e.g. ruby laser, Ti:sapphire laser, semiconductor laser.
Gas laser - e.g. He-Ne laser, Ar+ laser, CO2 laser, N2 laser, HCN laser.
Dye laser - active medium: dye molecules in liquid solvent (sometimes in solids also).
(B) By mode of operation
CW
Pulsed
(C) By pumping and laser levels
3-level laser
4-level laser
Introduction to semiconductor lasers, and its working. construction of semiconductor laser, Ga As laser, and construction, achievement of population inversion, pumping.
Photonic crystals are periodic dielectric structures that have a band gap that forbids propagation of a certain frequency range of light. This property enables one to control light with amazing facility and produce effects that are impossible with conventional optics.Photonic crystals can be fabricated for one, two, or three dimensions. One-dimensional photonic crystals can be made of layers deposited or stuck together. Two-dimensional ones can be made by photolithography, or by drilling holes in a suitable substrate. Fabrication methods for three-dimensional ones include drilling under different angles, stacking multiple 2-D layers on top of each other, direct laser writing, or, for example, instigating self-assembly of spheres in a matrix and dissolving the spheres
Cylindrical and spherical coordinates shalinishalini singh
In this Presentation, I have explained the co-ordinate system in three plain. ie Cylindrical, Spherical, Cartesian(Rectangular) along with its Differential formulas for length, area &volume.
This includes basic laser principles which are required to understand working of any laser system. It consists of the terms like excitation, de-excitation, population inversion, optical resonator, pumping source, active system and basic laser action.
A laser is a device that generates light by a process called STIMULATED EMISSION.
The acronym LASER stands for Light Amplification by Stimulated Emission of Radiation
Semiconducting lasers are multilayer semiconductor devices that generates a coherent beam of monochromatic light by laser action. A coherent beam resulted which all of the photons are in phase.
Contents
Definition of a laser
Emission and absorption of radiation
Population Inversion
Optical Feedback
Fundamentals of laser operation
Laser Hazards
This pdf is about the Schizophrenia.
For more details visit on YouTube; @SELF-EXPLANATORY;
https://www.youtube.com/channel/UCAiarMZDNhe1A3Rnpr_WkzA/videos
Thanks...!
Deep Behavioral Phenotyping in Systems Neuroscience for Functional Atlasing a...Ana Luísa Pinho
Functional Magnetic Resonance Imaging (fMRI) provides means to characterize brain activations in response to behavior. However, cognitive neuroscience has been limited to group-level effects referring to the performance of specific tasks. To obtain the functional profile of elementary cognitive mechanisms, the combination of brain responses to many tasks is required. Yet, to date, both structural atlases and parcellation-based activations do not fully account for cognitive function and still present several limitations. Further, they do not adapt overall to individual characteristics. In this talk, I will give an account of deep-behavioral phenotyping strategies, namely data-driven methods in large task-fMRI datasets, to optimize functional brain-data collection and improve inference of effects-of-interest related to mental processes. Key to this approach is the employment of fast multi-functional paradigms rich on features that can be well parametrized and, consequently, facilitate the creation of psycho-physiological constructs to be modelled with imaging data. Particular emphasis will be given to music stimuli when studying high-order cognitive mechanisms, due to their ecological nature and quality to enable complex behavior compounded by discrete entities. I will also discuss how deep-behavioral phenotyping and individualized models applied to neuroimaging data can better account for the subject-specific organization of domain-general cognitive systems in the human brain. Finally, the accumulation of functional brain signatures brings the possibility to clarify relationships among tasks and create a univocal link between brain systems and mental functions through: (1) the development of ontologies proposing an organization of cognitive processes; and (2) brain-network taxonomies describing functional specialization. To this end, tools to improve commensurability in cognitive science are necessary, such as public repositories, ontology-based platforms and automated meta-analysis tools. I will thus discuss some brain-atlasing resources currently under development, and their applicability in cognitive as well as clinical neuroscience.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Richard's entangled aventures in wonderlandRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
Comparing Evolved Extractive Text Summary Scores of Bidirectional Encoder Rep...University of Maribor
Slides from:
11th International Conference on Electrical, Electronics and Computer Engineering (IcETRAN), Niš, 3-6 June 2024
Track: Artificial Intelligence
https://www.etran.rs/2024/en/home-english/
Richard's aventures in two entangled wonderlandsRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
Normal Cell Metabolism:
Cellular respiration describes the series of steps that cells use to break down sugar and other chemicals to get the energy we need to function.
Energy is stored in the bonds of glucose and when glucose is broken down, much of that energy is released.
Cell utilize energy in the form of ATP.
The first step of respiration is called glycolysis. In a series of steps, glycolysis breaks glucose into two smaller molecules - a chemical called pyruvate. A small amount of ATP is formed during this process.
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to “burn” the pyruvates made in glycolysis to get more ATP.
The last step in the breakdown of glucose is called oxidative phosphorylation (Ox-Phos).
It takes place in specialized cell structures called mitochondria. This process produces a large amount of ATP. Importantly, cells need oxygen to complete oxidative phosphorylation.
If a cell completes only glycolysis, only 2 molecules of ATP are made per glucose. However, if the cell completes the entire respiration process (glycolysis - Kreb's - oxidative phosphorylation), about 36 molecules of ATP are created, giving it much more energy to use.
IN CANCER CELL:
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
introduction to WARBERG PHENOMENA:
WARBURG EFFECT Usually, cancer cells are highly glycolytic (glucose addiction) and take up more glucose than do normal cells from outside.
Otto Heinrich Warburg (; 8 October 1883 – 1 August 1970) In 1931 was awarded the Nobel Prize in Physiology for his "discovery of the nature and mode of action of the respiratory enzyme.
WARNBURG EFFECT : cancer cells under aerobic (well-oxygenated) conditions to metabolize glucose to lactate (aerobic glycolysis) is known as the Warburg effect. Warburg made the observation that tumor slices consume glucose and secrete lactate at a higher rate than normal tissues.
8. Absorption
• An atom initially at level one (ground level)
receives an external stimulus (energy).
• Energy raises it to level two (an excited state)
9. Spontaneous emission
• Atom in an excited state (high energy level)
falls back to a less excited state, emitting a
photon of light.
• This is called spontaneous or radiative
emission.
10. • Spontaneous emission is random
• Atoms involved in spontaneous emission may
produce monochromatic light…
• … but the phases of the waves will be different
(non-coherent) and …
• … they will travelling in different directions.
11. Stimulated emission
• Emission stimulated by another photon.
• The emitted photon is in the same direction
and in phase with the incident photon.
12. Population inversion
• Stimulated emission is the basis of the laser,
but you need many more atoms in the excited
state than the ground state. This is called
population inversion. It is achieved by
pumping.
Most atoms in ground state
Most atoms in excited state
(population inversion)
13. Metastable states
To achieve population inversion we must have
metastable states. These are excited states
where electrons stay for unusually long times.
14. Metastable states
Normally an electron in an excited state will
make the transition to a lower state in a time
of 10-7s. In contrast an electron may stay in a
metastable state for 10-3s.
15. • Laser equipment has three basic components:
– a resonant optical cavity
– a gain medium (active medium) and
– a pump source to excite the particles in the gain
medium.
16. • Active medium placed between two mirrors.
• Light bounces up and down between the
mirrors resonantly.
• Laser cavity made up of two mirrors, one of
which is semi-transparent to release the laser
that is generated in the cavity.
17. • Stimulated emission process takes place in the
gain medium.
• Gain medium amplifies light of any direction.
• However, only the light that bounces up and
down between the resonator mirrors is
amplified many times and therefore reaches a
high intensity.
18. • Monochromatic because the photon energy
has to match a particular energy transition.
• Since the amplification process maintains the
phase and direction of the light, the laser
output is directional and coherent.
19. • The active particles in the laser gain medium
need to be in a state of inversion for the laser
to operate.
• This is done through a process known as
pumping.
• The beam gains an extra photon whenever an
atom returns to the ground state
20. • The beam (laser) is reflected back and forth in
the cavity until it has enough intensity to be
sent out of the cavity.
• After that, the flash bulb can again excite
enough atoms for the creation of a new pulse.
21. • Laser is released continuously in a Continuous
Wave (CW) laser.
• An obstacle is placed in the laser cavity to stop
the laser discharge.
• The obstacle is removed when the flash bulb
has excited a large number of atoms it
releasing one gigantic pulse.
23. Helium-Neon laser
• The helium is used to create population
inversion in the neon. An electric field is used
to excite the Helium to a metastable state
20.61 eV above its ground level. When this
metastable helium atom collides with a neon
atom it excites the neon atom to a 20.66 eV
metastable state. The extra 0.05 eV comes
from the helium’s kinetic energy and the
helium atom is now back in its ground state.
24. Helium-Neon laser
The neon atoms transition to a
18.7 eV state, giving out photons
of λ = 632.8 nm. These photons
are reflected by mirrors at the
ends of the laser tube causing
stimulated emission in other
metastable neon atoms.
25. Helium-Neon laser
One of the mirrors is semi
transparent, allowing the
monochromatic, coherent,
directional and very intense
laser beam to emerge.
