Saturday, 14 June 2014

Inhaling, exhaling

April 3, 2014

PHOTO: P.V. SIVAKUMAR

How does inhaled oxygen go out as carbon dioxide from our body while breathing?

PAVITHRA

Chennai

While we breathe, we inhale oxygen along with nitrogen and carbon dioxide which co-exist in air. The inhaled air reaches lungs and enters alveoli where oxygen diffuses out from alveoli into blood, which enters into lungs via pulmonary capillaries, and carbon dioxide diffuses into alveoli from blood. This simple diffusion happens because of partial pressure difference between oxygen and carbon dioxide in blood and alveoli.

In alveoli, partial pressure of oxygen is relatively higher than carbon dioxide whereas, in the blood which enters in to the lungs, partial pressure of carbon dioxide is higher than oxygen.

Carbon dioxide entered into the alveoli by diffusion will be exhaled by lungs while we breathe. Blood leaving the pulmonary capillaries is rich in oxygen and it goes to the left atrium and pumped by heart into the systemic circulation of our body.

For our body cells to perform various functions, they need energy, and this energy is generated by producing ATP molecules via burning fuel molecules such as carbohydrates using oxygen.

The side product of this reaction is carbon dioxide. So in the body cells, partial pressure of carbon dioxide is higher than oxygen.

Hence, when oxygen rich blood reaches body cells by systemic circulation, because of partial pressure gradient, oxygen will diffuse into the body cells and carbon dioxide will diffuse into blood.

Now the carbon dioxide rich blood will return to the heart (right atrium) and then pumped into lungs. In the lungs, carbon dioxide will be exhaled as explained in the beginning. This process is a cycle and oxygen is taken up and carbon dioxide is released out continuously in our body.

Dr. K. K. CHERALATHAN

Associate Professor

Materials Chemistry Division

School of Advanced Sciences

VIT University, Vellore

Copyright© 2014, The Hindu

Plants use scents to attract or repel insects

April 3, 2014

K.R. DEEPAK

Flowering plants attract pollinating insects with scent from their flowers and bright colours. Plants are able to adjust their scent bouquet to their needs to attract in a more targeted manner useful insects that kill pests.

Colour perception

June 12, 2014

Why does the perceived colour of a tree-covered mountain change from green to indigo to violet as the distance of the observer from the mountain successively increases?

VITTHAL JOSHI

Dehradun, Uttarakhand

Sunlight consists of all visible wavelengths from violet to red. Earth’s atmosphere consists of gas molecules (78 per cent Nitrogen, 21 per cent Oxygen, 1 per cent Argon and traces of water vapour, hydrogen etc.) dust particles, smoke, water droplets etc.

The size of the gas molecules is very small (1000 times approximately) when compared to the wavelength of the visible light and hence the scattering of sunlight by these gas molecules is wavelength dependent. So, short wavelength radiations like violet and blue are scattered more (Rayleigh scattering).

When an observer sees a mountain under sunlight, he not only sees the light coming from the mountain (trees and plants) but also the sunlight scattered by the gas molecules of atmosphere (more correctly, troposphere) present between him and the mountain.

When he looks close to mountain, light from the mountain is more than the light scattered from the atmosphere. Hence, it appears green. However, when he looks at the same mountain at larger distances, length of the atmosphere is increased and also the intensity of light coming from the mountain is reduced.

As a result, light scattered by the gas molecules present in the atmosphere is more than the light from the mountain. So, it appears blue at long distances. Generally, blue colour appears predominantly over violet as it is more sensitive to human eyes.

One may ask what happens to the scattering of sunlight by dust, smoke particles present in atmosphere. The size of these particles is comparable or larger than the wavelength of the visible light. Scattering of sunlight by these particles has negligible wavelength dependence (i.e. all colours are scattered uniformly and hence appears white). However, this white light intensity is very small compared to blue light scattered by the gas molecules.

DR. K. SARAVANAKUMAR

Assistant Professor of Physics

Bannari Amman Institute of Technology

Sathyamangalam, Tamil Nadu

Copyright© 2014, The Hindu

Turing’s thesis on morphogenesis validated

April 3, 2014

 

Shubashree Desikan

A zebra’s stripes shows a pattern.— photo: AFP

A zebra’s stripes shows a pattern.— photo: AFP

Ever wondered what causes the variety of patterns we see in nature — a zebra’s stripes, the leopard’s spots or the alternating arrangement of leaves on a plant’s branches? How do cells which are identical to start with, differentiate and form regular patterns? There indeed is a scientific explanation for it, and it has been now validated by experiments, too.

In their paper, recently published in the Proceedings of National Academy of Sciences , Nathan Tompkins and others describe an experiment involving a reaction-diffusion system which evolves patterns that can lead to cell differentiation.

Theoretically this was worked out nearly 60 years ago —Alan Turing came up with an explanation for the origin of static patterns in nature in 1952. In a seminal paper he outlined that chemicals diffusing across identical cells and interacting with each other would result in the cells developing differences in chemical concentrations and this would lead to their getting differentiated further. For instance, when sugar is dissolved in water, it spreads evenly through the water until every cell has equal concentration of sugar.

But if there are two species of chemicals diffusing through, an activator and inhibitor, for instance, what would happen is quite different. Let us say, this happens in a linear array of cells. There would, after some time, be a different quantity of each species of chemical in the different cells. This would be further complicated if the chemicals interacted with each other.

Using differential equations to describe this reaction-diffusion process, Turing predicted that after some time, there could emerge six patterns, some of which he identified with existing patterns in biology. To prove this, Dr. Tompkins model this process in the lab and show that their experimental system replicates five of these patterns and a further throws up a seventh, hitherto unpredicted pattern.

When asked how, given that they are studying small numbers of cells, they can be sure that the patterns they are seeing are indeed genuinely periodic patterns, Seth Fraden, Department of Physics, Brandeis University, a member of the collaboration, says in an email: “We use small numbers of drops in rings, but we also used long linear arrays in the order of 100 drops and even larger hexagonal, two-dimensional arrays of the order of 10,000 drops… We believe the patterns are genuine because they appear where the model predicts them.”

Copyright© 2014, The Hindu

Monday, 2 June 2014

Trajectory correction of Mars mission likely by June 11


Chennai, Jun 2 (PTI) Indian Space Research Organisation
is likely to perform its next trajectory correction manoeuvre
on its Mars Orbiter mission on June 11.

    As its Mars mission is "on intended track" and was
proceeding towards the red planet with "good health," ISRO had
earlier announced that the trajectory correction manoeuvre
scheduled for April was not necessary and postponed it for
this month.

    "The mission is in good health and is on the intended
track. We have planned the next trajectory correction
manoeuvre of Mars mission on June 11. It is yet to be
finalised," a senior ISRO official told PTI.

     The spacecraft has now crossed two third of the total
distance -- 480 million km approximately, they said.
Another trajectory correction manoeuvre has been planned
in August before the space agency performs Mars Orbit
Insertion in September.

    The Mars mission, which was launched from Sriharikota on
November 5 last year with an aim to reach the red planet's
atmosphere by September 24 this year, had already crossed the
half-way mark on April 9.

   ISRO scientists are continuously monitoring the
spacecraft using its Deep Space Network complemented by that
of NASA-JPL.

   The Rs 450-crore project is expected to provide the
scientific community better opportunities in planetary
research. PTI

Friday, 30 May 2014

14 Indian Scientists Who Changed The World. And Things You Probably Didn’t Know About Them!

Shreya Pareek

May 23, 2014

http://www.thebetterindia.com/10725/12-indian-scientists-changed-the-world-inspiring/#sthash.4g7Ib3ch.dpuf

 

Science is important part of our everyday lives, even more than we notice. From our fancy gadgets to the the fan that throws air in a hot summer day. From The refrigerator that cools us off to the electricity that runs our lives, it is all gift of science and technology.

I wonder what would we be doing if none of these things were invented? How often we take out time to think about those extra ordinary minds who made life easier for us? Here is the list of 12 Indian scientists who achieved a global recognition-

1. CV Raman

cv raman

Chandrasekhara Venkata Raman, for his pioneering work on scattering of light, won the Nobel Prize for Physics in 1930. Born in Tiruchirapalli on November 7, 1888, he was the first Asian and first non-White to receive any Nobel Prize in the sciences. Raman also worked on the acoustics of musical instruments. He was the first to investigate the harmonic nature of the sound of the Indian drums such as the tabla and the mridangam.

He discovered that, when light traverses a transparent material, some of the deflected light changes in wavelength. This phenomenon is now called Raman scattering and is the result of the Raman effect.

In October 1970, he collapsed in his laboratory. He was moved to hospital and the doctors gave him four hours to live. He survived and after a few days refused to stay in the hospital as he preferred to die in the gardens of his Institute surrounded by his flowers. He died of natural causes on 21 November 1970.

Before dying, Raman told his students,

Do not allow the journals of the Academy to die, for they are the sensitive indicators of the quality of Sccience being done in the country and whether science is taking root in it or not.

2. Homi J. Bhabha

homi_j_bhabha

Picture source

Born on October 30, 1909 in Bombay, Homi Jehangir Bhabha played an important part in contribution to The Quantum Theory.

He was the first one to become the Chairman of Atomic Energy Commission of India. Having started his scientific career in nuclear physics from Great Britain, Bhabha returned to India and played a key role in convincing the Congress Party’s senior leaders, most notable Jawaharlal Nehru, to start the ambitious nuclear programme.

Bhabha is generally acknowledged as the father of Indian nuclear power. But few people know that he was absolutely against India manufacturing atomic bombs even if the country had enough resources to do so. Instead he suggested that the production of an atomic reactor should be used to lessen India’s misery and poverty.

He died when Air India Flight 101 crashed near Mont Blanc on 24 January 1966. Many possible theories of the crash came up including a conspiracy theory in which Central Intelligence Agency (CIA) is involved in order to paralyze India’s nuclear program.

3. Visvesvaraya

sirmv_MV

Sir Mokshagundam Visvesvaraya, born on 5 September 1860, was a notable Indian engineer, scholar, statesman and the Diwan of Mysore during 1912 to 1918. He was a recipient of the Indian Republic’s highest honour, the Bharat Ratna.

Sir M V suggested India to be put under the industrialized nations as he believed that India can become developed through industries.

He has the credit of inventing ‘automatic sluice gates’ and ‘block irrigation system’ which are still considered to be marvels in engineering.

Since river beds were costly, he came up with an efficient way of filtering water through ‘Collector Wells’ in 1895 which was rarely seen anywhere in the world. (Source)

4. Venkatraman Radhakrishnan

Venkatraman

Picture source

Venkatraman Radhakrishnan was born on May 18, 1929 in Tondaripet, a suburb of Chennai. Venkataraman was a globally renowned space scientist and member of the Royal Swedish Academy of Sciences.

He was an internationally acclaimed Astrophysicist and also renowned for his design and fabrication of ultralight aircraft and sailboats.

His observations and theoretical insights helped the community in unraveling many mysteries surrounding pulsars, interstellar clouds, galaxy structures and various other celestial bodies. He died at the age of 81 in Bangalore.

5. S. Chandrashekar

s chandrasekhar

Picture source

Born on October 19, 1910 in Lahore, British India, he was awarded the 1983 Nobel Prize for Physics for his mathematical theory of black holes. The Chandrasekhar limit is named after him. He was nephew of CV Raman. Chandra became a United States citizen in 1953.

His most celebrated work concerns the radiation of energy from stars, particularly white dwarf stars, which are the dying fragments of stars. He died on August 21, 1995, at the age of 82 in Chicago.

6. Satyendra Nath Bose

SatyenBose1925

Born on January 1, 1894 in Calcutta, SN Bose was an Indian physicist specialising in quantum mechanics. He is of course most remembered for his role played in the class of particles ‘bosons‘, which were named after him by Paul Dirac to commemorate his work in the field.

Bose adapted a lecture at the University of Dhaka on the theory of radiation and the ultraviolet catastrophe into a short article called “Planck’s Law and the Hypothesis of Light Quanta” and sent it to Albert Einstein. Einstein agreed with him, translated Bose’s paper “Planck’s Law and Hypothesis of Light Quanta” into German, and had it published in Zeitschrift für Physik under Bose’s name, in 1924. This formed the basis of the Bose-Einstein Statistics.

In 1937, Rabindranath Tagore dedicated his only book on science, Visva–Parichay, to Satyendra Nath Bose. The Government of India awarded him India’s second highest civilian award, the Padma Vibhushan in 1954.

7. Meghnad Saha

saha

Picture source

Born on October 6, 1893 in Dhaka, Bangladesh. Meghnad Saha’s best-known work concerned the thermal ionisation of elements, and it led him to formulate what is known as the Saha equation. This equation is one of the basic tools for interpretation of the spectra of stars in astrophysics. By studying the spectra of various stars, one can find their temperature and from that, using Saha’s equation, determine the ionisation state of the various elements making up the star.

He also invented an instrument to measure the weight and pressure of solar rays. But did you know, he was also the chief architect of river planning in India? He prepared the original plan for the Damodar Valley Project.

8. Srinivasa Ramanujan

RamanujanSrinivasa

Picture source

Born on December 22, 1887 in Tamil Nadu, Ramanujam was an Indian mathematician and autodidact who, with almost no formal training in pure mathematics, made extraordinary contributions to mathematical analysis, number theory, infinite series, and continued fractions.

By age 11, he had exhausted the mathematical knowledge of two college students who were lodgers at his home. He was later lent a book on advanced trigonometry written by S. L. Loney.[5][22] He completely mastered this book by the age of 13 and discovered sophisticated theorems on his own.

We hadn’t known before that he faced a lot of health problems while living in England due to scarcity of vegetarian food. He returned to India and died at a young age of 32.

Ramanujan’s home state of Tamil Nadu celebrates 22 December (Ramanujan’s birthday) as ‘State IT Day’, memorializing both the man and his achievements.

9. Jagadish Chandra Bose

J.C.Bose
Picture Source

Acharya J.C. Bose was a man of many talents. Born on 30 November, 1858 in Bikrampur, West Bengal, he was a polymath, physicist, biologist, botanist and archaeologist. He pioneered the study of radio and microwave optics, made important contributions to the study of plants and laid the foundation of experimental science in the Indian sub-continent. He was the first person to use semiconductor junctions to detect radio signals, thus demonstrating wireless communication for the first time. What’s more, he is also probably the father of open technology, as he made his inventions and work freely available for others to further develop. His reluctance for patenting his work is legendary.

Another of his well known inventions is the crescograph, through which he measured plant response to various stimuli and hypothesized that plants can feel pain, understand affection etc.

While most of us are aware of his scientific prowess, we might not be aware of his talent as an early writer of science fiction! He is in fact considered the father of Bengali science fiction.

10. Vikram Sarabhai

Vikram_Sarabhai
Picture Source

Considered as the Father of India’s space programme, Vikram Sarabhai was born on on 12 August, 1919 in the city of Ahmedabad in Gujarat. He was instrumental in the setting up of the Indian Space Research Organization (ISRO), when he successfully convinced the Indian government of the importance of a space programme for a developing nation after the launch of the Russian Sputnik, in his quote:

There are some who question the relevance of space activities in a developing nation. To us, there is no ambiguity of purpose. We do not have the fantasy of competing with the economically advanced nations in the exploration of the moon or the planets or manned space-flight.
But we are convinced that if we are to play a meaningful role nationally, and in the community of nations, we must be second to none in the application of advanced technologies to the real problems of man and society.

(source)

He was awarded the Padma Bhushan in 1966 and the Padma Vubhushan after his death in 1972. While everyone knows of his primary role in the establishment of ISRO, perhaps many of us do not know that he was also the force behind the establishment of many other Indian institutes of repute, most notably the Indian Institute of Management, Ahmedabad (IIM-A) and the Nehru Foundation for Development.

11. Salim Ali

Salim_ali_mns

Sálim Moizuddin Abdul Ali, born on November 12, 1896 in Mumba,i was an ornithologist and naturalist. Salim Ali was among the first Indians to conduct systematic bird surveys across India and his bird books helped develop ornithology in the sub-continent.

This Birdman of India was the key figure behind the Bombay Natural History Society after 1947 and used his personal influence to garner government support for the organisation. He was awarded India’s second highest civilian honour, the Padma Vibhushan in 1976.

12. Har Gobind Khorana

08_khorana_pu

Picture source

Born on January 9, 1922 Raipur village in West Punjab (now in Pakistan), Khorana was an Indian-American biochemist who shared the 1968 Nobel Prize for Physiology or Medicine with Marshall W. Nirenberg andRobert W. Holley for research that helped to show how the order of nucleotidesin nucleic acids, which carry the genetic code of the cell, control the cell’s synthesis of proteins.

In 1970, Khorana became the first to synthesize an artificial gene in a living cell. His work became the foundation for much of the later research in biotechnology and gene therapy.

How many are aware that the University of Wisconsin-Madison, the Government of India (DBT Department of Biotechnology), and the Indo-US Science and Technology Forum jointly created the Khorana Program in 2007? The mission of the Khorana Program is to build a seamless community of scientists, industrialists, and social entrepreneurs in the United States and India. Khorana died of natural causes on November 9, 2011 at the age of 89.

13. Birbal Sahni

birbalsahniPicture Source

Born on November 14, 1891 in West Punjab, Sahni was an Indian paleobotanist who studied the fossils of the Indian subcontinent. He was also a geologist who took an interest in archaeology. His greatest contributions lie in the study of the plants of India as well as paleobotany.

He was elected a Fellow of the Royal Society of London (FRS) in 1936, the highest British scientific honor, awarded for the first time to an Indian botanist.

He was a founder of The Paleobotanical Society which established the Institute of Palaeobotany on 10 September 1946 and which initially functioned in the Botany Department of Lucknow University. Sahni died 10 April 1949 due to a heart attack.

14. APJ Abdul Kalam

apj kalam

Picture source

Avul Pakir Jainulabdeen Abdul Kalam, born on October 15, 1931 is an Indian scientist who worked as an Aerospace engineer with Defence Research and Development Organisation (DRDO) and Indian Space Research Organisation (ISRO).

Kalam started his career by designing a small helicopter for the Indian Army. Kalam was also part of the INCOSPAR committee working under Vikram Sarabhai, the renowned space scientist. In 1969, Kalam was transferred to the Indian Space Research Organization (ISRO) where he was the project director of India’s first indigenous Satellite Launch Vehicle (SLV-III) which successfully deployed the Rohini satellite in near earth’s orbit in July 1980.

He also served as the 11th President of India from 2002 to 2007. Kalam advocated plans to develop India into a developed nation by 2020 in his book India 2020. He has received several prestigious awards, including the Bharat Ratna, India’s highest civilian honour. Known for his love for children, did you know that he had set a goal of meeting 100,000 students in the 2 years after his resignation from the role of scientific adviser in 1999? May he continue to inspire millions.

Tuesday, 27 May 2014

A new way to turn light into matter

May 21, 2014

Updated: May 21, 2014 22:47 IST

Shubashree Desikan

The title begs the question – did older ways to turn light into matter exist? Well, that is exactly what photo-electric effect does! So what’s new here is that we are talking about using direct, pairwise, photon-photon interactions to produce electron-positron pairs, which has not been possible to achieve, experimentally. Writing in Nature Photonics, O.J. Pike et al of Imperial College, London and Max-Planck Institut, Heidelberg, have come up with a suggestion for an experiment in which this can be achieved. They further reiterate their idea by running a Monte Carlo simulation which demonstrates that the dominant channel, with proper design of the experimental apparatus, is the two-photon (Breit-Wheeler) process of pair production.

Quantum electrodynamics does allow for the interconversion of photons and matter, namely, electron-positron pairs can annihilate to give photons; pairs of photons can interact to give electron-positron pairs and even vacuum, or empty space, can undergo polarisation to give out electron-positron pairs.

There are various energy constraints that make some of these processes difficult to achieve experimentally, especially that of two photons colliding to give out a pair.

Pike et al have proposed an experimental scheme to build a table-top photon-photon collider which will produce electron-positron pairs. They suggest shooting ultra-relativistic electrons into a gold target where, due to retardation, the electrons emit high-energy photons. This beam is fired into a vacuum holhlraum (a hohlraum is a cavity whose walls are in equilibrium with the radiation inside. So that the radiant energy that comes out of a small hole in it is like a blackbody radiation.) Inside the vacuum holhlraum, the light beam interacts and produces the electron-positron pairs, which, in turn, can be picked up using a magnetic field outside the cavity.

The authors suggest that the dominant mechanism in the pair production will be the two-photon collision process, and this is an experimental feat that has not been achieved so far. Further they perform Monte Carlo simulations and solve the cross-section equations to corroborate this.

Though this simulation does not bring in anything new theoretically, it will be quite a feat to have a table-top photon-photon collider as they appear to suggest.

However, since they are suggesting that the energies of the pairs produced are in the range of 100 MeV to a GeV, it is debatable how useful this would be in high-energy physics experiments. It may be useful to probe quark resonances, but then, these have already been probed in other particle accelerators.

Keywords: Photon-photon interactions, electron-positron pairs, High energy physics experiments, quantum electrodynamics, high energy photons

May 26, 2014

The science of science writing

readerseditor@thehindu.co.in

Last week there was an exchange that brought out the clear distinction between writing about social sciences and science. On May 22, 2014, Shubashree Desikan wrote an interesting piece titled ‘A new way to turn light into matter’ in the weekly Science and Technology section. Her article was about a scientific paper published in a reputed journal, Nature Photonics , in which scientists from the Imperial College, London and Max-Planck Institut, Heidelberg, had argued for building a tabletop photon-photon collider that will produce electron-positron pairs.

One of our readers from Chennai, Mr. Raghavan, was quick to point out an erroneous comparison. The first paragraph of the article read: “The title begs the question — did older ways to turn light into matter exist? Well, that is exactly what photo-electric effect does!” Mr. Raghavan wrote to say that photo-electric effect is not turning light into matter, but is generation of electricity due to the influence of light and has nothing to do with the pair production and annihilation of matter explained in the article. Shubashree was quick to regret the confusion her piece created between photo-electric effect and pair production. She said: “Photo-electric effect does not create electron-positron pairs and this was not meant to be implied. In the sense that photo-electric effect and pair production, as we observe these, are only allowed by a quantum theory, they are equally contrary to a classical perception and that was the intention of mentioning the photo-electric effect as an example. It was not to say that photo-electric effect involved electron-positron pair production.”

The inherent strength of The Hindu is its commitment to cover a range of topics and develop in-house expertise in handling various domains of knowledge. From diplomacy and strategic affairs to banking, from sports to macroeconomics, from law and constitutional affairs to agriculture, from rural affairs to development models, from politics of governance to the politics of freedom of expression, the newspaper has invested in talents who can handle these important issues with expertise and élan.

Challenging field

The science and technology section is an important one in the newspaper. Apart from having a specialised weekly page on the topic, the newspaper covers many critical developments in the fields of science and technology. The Council for the Advancement of Science Writing rightly states that of all the journalism specialties, science writing may well be the most challenging and rewarding. Science journalists cover an impressive array of fields where advances are rapid, their impact on the society wide-reaching and the boundaries are constantly being redefined. This field is challenging because no writer can be qualified in any university to cover the range that includes genetics and astrophysics, atomic science and pharmacology, marine biology and organic chemistry, toxicity and environmental sciences, and human body and beyond. It is rewarding because science journalism helps us understand the new possibilities that these sciences have opened up for us, and also address a range of ethical issues. It takes enormous skill to present arcane and complex news of scientific discoveries and explorations in a language that is accessible to the general reader. The distinctiveness of science journalism lies in producing a prose that is simple but not simplistic, that respects the intelligence of a reader without being condescending. A science journalist is a truly multi-tasking person as the subjects he/she covers are very wide and deep both in their scope and content.

Role of science journalist

At the World Congress of Science Journalists held in Helsinki last year, the leading theme was critical thinking in the public sphere. The conference spoke about the most burning ethical issues and the values ingrained in the everyday work of a science journalist. From basic human rights and codes of conduct to matters of accessibility of scientific knowledge and political debates, it asked the participants: what is the significance of science journalism and science communication in the realisation of shared scientific advancement and culture in different parts of the world? It also looked at the question of vulnerability in the face of natural disasters, the world economic crisis, cultural changes and questions of health and well-being and the role of a science journalist in providing credible scientific information that can lead to informed choices.

The fundamental difference between writing about social sciences and science and technology is in the use of analogous examples to explain and elucidate a point or a view. While employing an analogous example enriches our understanding in social sciences, it may backfire as in the case of Subashree’s report because of extreme specificity of each subject. An analogy in a science story forces the writer to add annotations and afterwards to explain the intended meaning. Being a science journalist is demanding. It is not easy to explain Albert Einstein’s work in the language of Ernest Hemingway.

Copyright© 2014, The Hindu