SCIENCE & TECHNOLOGY

Imaging a lie through MRI
Dr S.S. Verma
W
e should follow the path of truth but telling lies is a bestowed character on human beings and used sometimes to hide more serious things particularly by criminals. Technology has taken over the social and spiritual methods of lie detection. 

Reducing emissions
R
esearchers from the University of Leicester and the British Geological Society (BGS) have proposed storing carbon dioxide in huge underground reservoirs as a way of reducing emissions — and have even identified sites in Western Europe that would be suitable.

THIS UNIVERSE
PROF YASH PAL
 
What is the average life of a star? Why do the stars in a constellation (for e.g. Orion or Saptarishi) appear to be permanent? 

Prof Yash Pal

Prof Yash Pal

 


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Imaging a lie through MRI
Dr S.S. Verma

We should follow the path of truth but telling lies is a bestowed character on human beings and used sometimes to hide more serious things particularly by criminals. Technology has taken over the social and spiritual methods of lie detection. A polygraph test is the standard lie-detection tool employed by law enforcement and intelligence agencies for nearly a century which measures the stress of telling a lie, as reflected in accelerated heart rate, rapid breathing, rising blood pressure, and increased sweating.

The polygraph is widely considered unreliable in scientific circles, partly because its effectiveness depends heavily on the intimidation skills of the interrogator. Moreover, sociopaths who don’t feel guilt and people who learn to inhibit their reactions to stress can slip through a polygrapher’s net.

Scientists and engineers are always working to devise a more effective technique to detect lies which can be helpful for easy identification of the culprits in the society. Scientists are making use of latest developed imaging techniques towards detecting lies by imaging deception in the brain itself. The major noninvasive neuroimaging techniques used are positron emission tomography (PET), single photon emission computed tomography (SPECT), and magnetic resonance imaging (MRI), along with electro — encephalography (EEG), an earlier technique for monitoring brain activity.

Advances in all these techniques are enabling scientists to produce remarkably detailed computer-screen images of brain structures and to observe neurochemical changes that occur in the brain as it processes information or responds to various stimuli. Each technique has its own advantages and each provides different information about brain structure and function.

MRI uses magnetic fields and radio waves to produce high quality two — or three-dimensional images of brain structures without use of ionising radiation (X-rays) or radioactive tracers.

Using MRI, scientists can image both surface and deep brain structures with a high degree of detail, and they can detect minute changes in these structures that occur over time.

Within the last few years, scientists have developed techniques that enable them to use MRI to image the brain as it functions. Functional MRI (fMRI) relies on the paramagnetic properties of blood to enable scientists to see images of blood flow in the brain as it is occurring.

Thus researchers can make movies of changes in brain activity with greater precision as patients perform various tasks or are exposed to various stimuli. When people lie, they use different parts of their brains than when they tell the truth, and these brain changes can be measured by functional magnetic resonance imaging (fMRI). By mapping the neural circuits behind deception, researchers are turning fMRI into a new kind of lie detector that’s more probing and accurate than the polygraph.

FMRI-based lie-detection systems seek to assess a more direct measure of deceit: the level of activity in brain areas linked with lying. Previous studies have shown that the brain appears more active when someone is telling a falsehood, especially the brain areas involved in resolving conflict and cognitive control.

Scientists think that lying is more cognitively complex than telling the truth, and therefore it activates more of the brain. Research has shown that brain-activity patterns change when a person is asked to, say, read emotionally charged words rather than neutral ones. The neural circuitry used for lie detection is significantly modified by emotion.

Developments in brain imaging will continue to provide new insights into relationships between brain and mind states, and into psychological processes that can be quantified objectively and used to provide other measures of brain output besides overt behaviour and inferences from psychology experiments.

Further, the real-life stimulus is critical if this technique is to be developed into a practical test of deception because physiologic responses can vary among individuals and, in some cases, can be regulated, the polygraph is not considered a wholly reliable means of lie detection.

The science behind fMRI lie detection is getting matured with astonishing speed. Researchers believe that fMRI should be tougher to outwit because it detects something much harder to suppress: neurological evidence of the decision to lie. The great danger is that something like fMRI is adopted as a means of lie detection and becomes the standard before it has been scientifically evaluated for this purpose. Scientists say that, like the physiological changes monitored during polygraphs, the brain-activity patterns measured during fMRI are not specific to deception, making it challenging to identify a brain pattern that definitively identifies a lie.

Some practical obstacles stand in the way of its widespread use: the scanners are huge, costly and sensitive to head movement.

With the development of technology, however, these limitations will be fixed and fMRI brain imaging equipment will become easily available and affordable, ensuring its increased use as a tool for lie detection.
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Reducing emissions

Researchers from the University of Leicester and the British Geological Society (BGS) have proposed storing carbon dioxide in huge underground reservoirs as a way of reducing emissions — and have even identified sites in Western Europe that would be suitable.

Their research, published in the journal, Planet Earth, reveals that CO2 can be contained in cool geological aquifers or reservoirs, where it can remain harmlessly for many thousands of years.

PhD research student, Ameena Camps, is working with Professor Mike Lovell at the University’s Department of Geology and with Chris Rochelle at BGS, investigating the storage of CO2.

Storing the gas in a solid form as a gas hydrate, or as a pool of liquid CO2 below a cap of hydrate cemented sediments, is believed to offer an alternative method of geological sequestration to the current practices of storage in warm, deep sediments in the North Sea.
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THIS UNIVERSE
PROF YASH PAL
 
What is the average life of a star? Why do the stars in a constellation (for e.g. Orion or Saptarishi) appear to be permanent? 
Images of unique areas of the brain involved in deception are recorded with functional MRI
Images of unique areas of the brain involved in deception are recorded with functional MRI

Life of a star depends on its mass. Strange as it might seem, bigger the mass shorter is its life! While a star with a mass like our sun might shine for about

 10 billion years, very heavy mass stars might end in a few million years. To understand this we have to have a general understanding of the way stars are born, how they live and the way they die.

Suppose we have a large cloud of dust and gas. It is quite likely that because of random fluctuations or some other cause some part of this cloud may come to be denser than its neighbourhood. In that case the surrounding regions would begin to gravitate towards the denser part. This is an accelerating process. Denser the inner part more is its attraction.

We therefore have a situation where the dust and the gas start falling inwards, leading to a compaction of the cloud. The falling material is subject to collisions and heating up of the dense cloud. The gravitational energy is being converted into heat energy. The central part of this cloud will be the hottest.

When we say that a gas is hot we also imply that its particles are moving with high random velocities and continuously colliding with each other. In fact temperature is a measure of the velocity of these particles.

Then something new happens. At very high temperatures atoms are ionized - we do not have neutral atoms anymore. The most abundant element is hydrogen, which after ionization is broken up into protons and electrons. Through a well-understood series of nuclear reactions and radioactivity we get the result that four protons can fuse into one helium nucleus and a lot of energy.

The energy comes from the fact that the mass of a helium nucleus is significantly less than the mass of four protons. This can happen only if the thermal energy of the protons is high enough to overcome the electrostatic repulsion between particles of like charges. As the temperature at the centre of the dense cloud rises the rate of the fusion reactions also increases. Rising temperature leads to a higher gas pressure till it is enough to support the inward gravitational pressure. At that stage the dense cloud is stabilized. It has become a star.

Our sun is one such star. This star would keep shining at about the same rate till the hydrogen supply near the core is exhausted.

Notice the remarkable mechanism that gives long term stability to stellar furnaces. Any increase in the internal temperature that would increase the energy production would also increase the internal pressure. As a result the star would expand, leading to a drop in the temperature and, hence, the rate of energy production. The reverse would happen if the internal temperature decreased. Stars are self-regulating furnaces.

From the above discussion it should be clear that if the material from which stars are formed is about the same, then the only thing that controls the brightness of the star is its mass. Very heavy stars will be able to compress the center to much higher temperature before the internal pressure rises enough to counter the force of the gravitational compression. A higher temperature also implies that the rate of reactions inside is much higher resulting in these stars being much brighter. This is a sensitive function. It turns out that stars that are ten times massive than our sun would produce energy, and consume their hydrogen fuel, at such a rate that they live a thousand times less than moderate stars like our sun. Even amongst stars the fat and the spendthrifts do not last long. While we have been talking about energy production in stars, let us not overlook that the stellar furnace is also creating heavier elements through fusion of light elements. This process does not stop at making of helium from hydrogen but in later stages of the stellar life, also leads to the synthesis of heavier elements. We will not go at this time into the details of how and when that happens. We would only say that the stars are believed to be the generators of all chemical elements of mass equal to and greater than carbon.

In the end let me say that nothing is permanent — not even the Saptarishi. Our life is too short compared to that of the stars. Even our history of a few thousand years is miniscule in length. Why only history, we humans have not been here for a long enough period to see a significant change in the appearance of the heavens. Yes the changing relative positions of stellar conditions even in historical times can be discerned. To be aware of big changes we have to look at the larger sample of astronomical observations. There we do see remnants of supernovae, neutron stars and evidence for black holes. These are all stages of the way some stars end their lives, sometimes to be born again in states completely invisible at the time of their birth. Top


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