Lasers operate by stimulating emission of radiation from their active medium. They produce coherent, monochromatic, collimated light beams. The first laser was created in 1960 using a ruby crystal as the active medium. Lasers have revolutionized science, technology and medicine with applications such as optical fiber communications, laser eye surgery, barcode scanners, laser pointers, Blu-ray players and more. Some key laser components include an energy source to pump the active medium, the active medium itself, and an optical resonator formed by mirrors to provide optical feedback.
Laser is a light source but it different from ordinary light sources due their peculiar characteristics. In general ordinary light produces due to spontaneous emission of radiation but in the case of lasers its due to the stimulated emission of radiation.
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The term "laser" originated as an acronym for "light amplification by stimulated emission of radiation
PRESENTATION 4- Basics of Laser in Dermatolgy
It includes -
Laser spectrum
Definition Laser
Classification of Lasers
Laser Theories
Laser terminology
Laser Hazards
Laser is a light source but it different from ordinary light sources due their peculiar characteristics. In general ordinary light produces due to spontaneous emission of radiation but in the case of lasers its due to the stimulated emission of radiation.
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The term "laser" originated as an acronym for "light amplification by stimulated emission of radiation
PRESENTATION 4- Basics of Laser in Dermatolgy
It includes -
Laser spectrum
Definition Laser
Classification of Lasers
Laser Theories
Laser terminology
Laser Hazards
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
Laser /certified fixed orthodontic courses by Indian dental academy Indian dental academy
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.
Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
0091-9248678078
This belongs to Physical Chemistry portion and it contains most of
things about laser working and principles.
By Aaryan Tyagi's Group
M.Sc. Applied Chemistry (1 Sem)
Amity University, Noida
Lasers in orthodontics /certified fixed orthodontic courses by Indian dent...Indian dental academy
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.
Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
0091-9248678078
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.
Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
00919248678078
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.
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.
Slide 1: Title Slide
Extrachromosomal Inheritance
Slide 2: Introduction to Extrachromosomal Inheritance
Definition: Extrachromosomal inheritance refers to the transmission of genetic material that is not found within the nucleus.
Key Components: Involves genes located in mitochondria, chloroplasts, and plasmids.
Slide 3: Mitochondrial Inheritance
Mitochondria: Organelles responsible for energy production.
Mitochondrial DNA (mtDNA): Circular DNA molecule found in mitochondria.
Inheritance Pattern: Maternally inherited, meaning it is passed from mothers to all their offspring.
Diseases: Examples include Leber’s hereditary optic neuropathy (LHON) and mitochondrial myopathy.
Slide 4: Chloroplast Inheritance
Chloroplasts: Organelles responsible for photosynthesis in plants.
Chloroplast DNA (cpDNA): Circular DNA molecule found in chloroplasts.
Inheritance Pattern: Often maternally inherited in most plants, but can vary in some species.
Examples: Variegation in plants, where leaf color patterns are determined by chloroplast DNA.
Slide 5: Plasmid Inheritance
Plasmids: Small, circular DNA molecules found in bacteria and some eukaryotes.
Features: Can carry antibiotic resistance genes and can be transferred between cells through processes like conjugation.
Significance: Important in biotechnology for gene cloning and genetic engineering.
Slide 6: Mechanisms of Extrachromosomal Inheritance
Non-Mendelian Patterns: Do not follow Mendel’s laws of inheritance.
Cytoplasmic Segregation: During cell division, organelles like mitochondria and chloroplasts are randomly distributed to daughter cells.
Heteroplasmy: Presence of more than one type of organellar genome within a cell, leading to variation in expression.
Slide 7: Examples of Extrachromosomal Inheritance
Four O’clock Plant (Mirabilis jalapa): Shows variegated leaves due to different cpDNA in leaf cells.
Petite Mutants in Yeast: Result from mutations in mitochondrial DNA affecting respiration.
Slide 8: Importance of Extrachromosomal Inheritance
Evolution: Provides insight into the evolution of eukaryotic cells.
Medicine: Understanding mitochondrial inheritance helps in diagnosing and treating mitochondrial diseases.
Agriculture: Chloroplast inheritance can be used in plant breeding and genetic modification.
Slide 9: Recent Research and Advances
Gene Editing: Techniques like CRISPR-Cas9 are being used to edit mitochondrial and chloroplast DNA.
Therapies: Development of mitochondrial replacement therapy (MRT) for preventing mitochondrial diseases.
Slide 10: Conclusion
Summary: Extrachromosomal inheritance involves the transmission of genetic material outside the nucleus and plays a crucial role in genetics, medicine, and biotechnology.
Future Directions: Continued research and technological advancements hold promise for new treatments and applications.
Slide 11: Questions and Discussion
Invite Audience: Open the floor for any questions or further discussion on the topic.
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
A brief information about the SCOP protein database used in bioinformatics.
The Structural Classification of Proteins (SCOP) database is a comprehensive and authoritative resource for the structural and evolutionary relationships of proteins. It provides a detailed and curated classification of protein structures, grouping them into families, superfamilies, and folds based on their structural and sequence similarities.
2. ight
mplification by
timulated
mission of
adiation
Term coined by Gordon Gould.
One of the most influential technological achievements of the 20th
century.
Laser is an optical device that generates intense beam of coherent
monochromatic light by Stimulated emission of radiation.
4. HISTORY OF LASER
In 1917, Albert Einstein established the basic fundamentals to built
a laser (quantum theory of light and photons & mechanism of
stimulated emission).
In 1954, the first maser was demonstrated by Charles Townes, A L
Schawlow which worked in the microwave range.
The first laser was designed by Theodore Maiman in 1960 and was
made by ruby.
8. 1. COHERENCE :
The light from a laser is said to be coherent, which means
that all the light waves have the same frequency and move in
phase together.
Ordinary light in contrast is out of phase.
ORDINARY LIGHT LASER LIGHT
9. 2. DIRECTIONALITY :
Lasers emit light that is highly directional, that is, laser light is
emitted as a relatively narrow beam in a specific direction.
Ordinary light, such as from a light bulb, is emitted in many
directions away from the source.
ORDINARY LIGHT LASER LIGHT
10. 3. MONOCHROMATICITY :
The light emitted from a laser is monochromatic, that is, it is
of one colour or wavelength.
In contrast, ordinary white light is a combination of many
colours or wavelengths of light.
4. HIGH INTENSITY
In laser, the light spreads in small region of space and in a small
wavelength range.
In an ordinary light source, light spreads out uniformly in all
directions.
Hence, laser light has greater intensity when compared to
ordinary light.
13. 1. Energy source or pump source
• Part of laser system that provides energy to the laser medium.
• Example of energy source include electric discharges, chemical
reactions, light from another laser.
• Type of energy source depends on laser medium.
• For eg: Excimer laser uses chemical reactions as energy source
Helium laser uses electric discharge etc…
2. Laser medium
• Also known as active medium or gain medium.
• System in which population inversion and hence stimulated
emission takes place.
• Laser medium determines the characteristics of laser light
emitted.
• Can be solid(Nd:YAG laser), liquid(dye laser) or gaseous(helium
neon laser).
14. 3. Optical resonator
• Laser medium is surrounded by two parallel mirrors which
provide feedback of light.
• One mirror is fully reflective (High Reflection mirror) and other
is partially reflective (Output coupler).
• Output coupler will allow some of the light to leave the optical
cavity to produce laser output beam.
• Two mirrors are whole called as OPTICAL RESONATOR.
15. PRINCIPLES OF WORKING OF A
LAsERIn lasers, photons are interacted in 3 ways with atoms:
1. Absorption of radiation
2. Spontaneous emission
3. Stimulated emission
ABSORPTION OF RADIATION
• It is the process by which electrons in the lower energy state
absorbs energy from photons to jump into higher energy level.
• It occurs because these electrons in the lower energy state need
extra energy to jump into higher energy level.
• Extra energy is provided from various sources like heat, electric
field or light etc.
16. • Absorption of light occurs only if the energy of incident photon
exactly matches energy difference of the 2 energy levels.
• This results in POPULATION INVERSION – it is the process of
achieving greater number of electrons in higher energy state as
compared to lower energy state.
ENERGY
LOWER ENERGY STATE
HIGHER ENERGY STATE
17. 2. SPONTANEOUS EMISSION
• It is the process by which electrons in the excited state return to
the ground state by emitting photons.
• Electron in excited state can stay only for a short period called as
life time of excited electrons which is 10-8 sec.
• Here electrons move naturally from one state to another and
emission of photons also occur naturally which constitute ordinary
incoherent light.
ENERGY
LOWER ENERGY STATE
HIGHER ENERGY STATE
PHOTONS
18. 3. STIMULATED EMISSION
• It is the process by which incident photon interacts with the
excited electron and forces it to return to the ground state.
• Hence light energy is supplied directly to the excited electron, so
electrons in the excited state need not wait for completion of
their lifetime.
• Here 2 photons are emitted, one is due to incident photon and
another is due to energy release of excited electron.
• All emitted photons have the same energy same frequency and
travel in same direction.
• Number of photons emitted depends on number of electrons in
higher energy level and incident light intensity.
34. 1. Solid state laser
• Uses solid as a laser medium – glass or crystalline materials are
used.
• Materials such as Sapphire (Al2O3), Neodymium doped yttrium
aluminium garnet (Nd:YAG), Neodymium doped glass (Nd:Glass)
etc are used as materials for laser medium.
• Nd:YAG is the most commonly used.
• The first solid state laser was Ruby laser – here ruby crystal is the
medium.
RUBY LASER Nd:YAG LASER
35. 2. Gas laser
• Laser medium is in the gaseous state.
• Type of gas used can determine the laser efficiency.
• Types : Helium Neon laser, Argon laser, carbon monoxide laser,
Excimer lasers etc.
Helium Neon laser CO2 laser
36. 3. Liquid laser
• Uses liquid as laser medium.
• Most common is Dye laser – organic dye as laser medium.
DYE LASER
37. 4.Semiconductor laser
• Also known as LASER DIODE.
• Play an important role in our everyday life.
• These lasers are very cheap, compact size, and consume low
power.
39. LASERS IN MEDICINE
Bloodless surgery
Fiber optic endoscope
to detect ulcers in the
intestine .
Lasers are used extensively in the
treatment of eye diseases particularly
to reattach a detached retina.
40. Used to remove caries or decayed
portion of teeth.
Liver and lung diseases could be treated using lasers.
To destroy cancerous and precancerous cells.
Used to study internal structure of microorganisms and cells.
41. To break up gall stones and
kidney stones.
To remove plague
clogging human
arteries.
Lasers are used in
cosmetic treatments
such as acne treatment,
hair removal etc…
42. LASERS IN INDUSTRY
# For precision
measurements and
leveling
Latching tool Milling tool
43. Laser light is used to collect the
information about the prefixed
prizes of various products in shops
and business establishments from
the barcode printed on the
product.
Welding and cutting of metal
45. LASERS IN COMMUNICATION
Laser communication systems are wireless
communications through the atmosphere.
Eg: Optical fiber communications, used particularly for long
distance optical data transmission, Free space optical
communications for inter satellite communications etc…
48. BIOLOGICAL EFFECTS OF LASER RADIATION
The unprotected human eye is extremely sensitive to laser
radiation and can be permanently damaged from direct or
reflected beams.
The area of the eye damaged by laser energy is dependent upon
the wavelength of the incident laser beam.
The retina, cornea and lens are the areas most commonly
damaged.
1. Laser effects on eye
49. 2. Laser effects on skin
Thermal (burn) injury is the most
common cause of laser induced
skin damage.
Thermal damage is generally
associated with laser operating at
exposure time greater than 10
microseconds and the wavelength
region near UV to infrared region.
• Retina: laser light in the visible to infrared spectrum can
cause damages to retina. These wavelengths are also known
as “retinal hazard region”
• Cornea and lens: laser light in the UV or far infrared spectrum
can cause damage to cornea and lens.
50. NOBEL PRIZE IN PHYSICS 2018
DONNA
STRICKLAND
GERARD
MOUROU
ARTHUR
ASHKIN
“For groundbreaking inventions in the field of LASER PHYSICS”
(Inventing optical tweezers and high power laser pulses)