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Archives – August, 2010

Desert Ants Can Count!

Life can be tough in deserts; for ants too! Ants use scents for navigation, they track back their scent trail to get back to their home. But in desert, scent trail is lost very soon in hot and windy conditions, so how do they navigate back to home. Well they count their steps! I will not reveal how scientists designed experiment to test this hypothesis. First watch this video, and then you can read their paper as well.

Leave a Comment August 26, 2010

Origin of The Word “Evolution”

When we think of the word “Evolution”, first thing that comes to everyone’s mind is Charles Darwin and his book Origin of Species which he wrote in 1859. So the question comes, did he coin the word evolution or it existed even before he wrote Origin of Species. Well, to learn about the history of the words, first thing we should do is lookup the dictionary, which not only gives various meanings of each word, but also mentions the year when the word was first used in print.

Merriam Webster:

Origin of EVOLUTION

Latin evolution-, evolutio unrolling, from evolvere

First Known Use: 1622

evolution  (ev·o·lu·tion)

Origin: early 17th century: from Latin evolutio(n-) ‘unrolling’, from the verb evolvere (see evolve). Early senses related to physical movement, first recorded in describing a tactical “wheeling” maneuver in the realignment of troops or ships. Current senses stem from a notion of “opening out” and “unfolding,” giving rise to a general sense of ‘development’

So what we find is that word evolution originated from Latin word evolutio, which means unrolling, something like unrolling of the scroll, and the word existed a couple of centuries before Darwin wrote Origin of Species. He infact did not even use the word evolution  in his book until the last line which was:

There is grandeur in this view of life, with its several powers, having been originally breathed by the Creator into a few forms or into one; and that, whilst this planet has gone circling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being evolved. [Abridged version of Origin of Species]

Darwin did not even prefer the choice of word evolution for describing — genetic adaptation of species to the environment as a result of natural selection, and breeding and mutation. He preferred other words such as “transmutation by means of natural selection”- tells Science historian Howard Markel in a NPR show. Infact, it was geologist Charles Lyell  who first used the word evolution for scientific purposes  in 1832 in a book he wrote about geology.  Darwin also did not like the word for another reason– it suggested the process as getting good, better, best and ultimately to perfection, which left the room for the idea of an ultimate creator and perfect creation. Darwin was totally against this idea of perfect creator and he described very carefully at various instances that the process of evolution is not unidirectional, and things can go opposite direction as well. Anyway, the word evolution caught up with public and scientists alike, thanks to Darwin’s followers who spread his theory, work and the word “Evolution” . So that’s how the word Evolution evolved!

Picture credit: Flickr user krossbow| Used under creative commons license

Info: NPR podcast

Leave a Comment August 26, 2010

Milky Way as Seen From Earth


Watch the galactic center of our Milky Way along with Perseid meteor shower, beautifully shot by Henry Lee at Joshua Tree National Park during period of August 12-15, 2010.

Leave a Comment August 25, 2010

Devastating Floods In Pakistan

The flood situation in Pakistan is getting bad to worse day by day and the image above shows what is left behind in most parts of north-western Pakistan, broken homes, lost lives, livelihood, spread of diseases, lack of basic amenities and total chaos. It’s one of the worst flood disaster that has happened in recent times, caused due to incessant month long monsoon rains. Currently 1/5th of Pakistan is under floods and it can get even worse in coming days.Blame it on Global warming or anything else, but the event is bizarre and has costed lives of so many people. While this single isolated event can’t be taken as proof of Global warming, but if you take into accounts all the climate extremities we have been observing in recent time, freezing cold winters, extreme hot and prolonged summers, prolonged rains such as these and earlier in other parts of India– it all points towards global warming as one of its cause. Indian Ocean has warmed up by 2 degree F since 1970. Warm oceans means more evaporation of water, it also heats up the air making it capable of holding more moisture: results- air can contain more moisture which then move into land where they trigger storms and bizarre rainfall patterns.

These images above shows the situation in Pakistan before and after the floods. The picture above was taken in 2009, while picture below was taken by satellite on Aug 19, 2010. Swollen Indus river can be clearly seen and the water is heading towards Kotri barrage before it flows into the sea. Barrage is still holding the water, but the level is rising and if it does overflow,  it will wreak havoc in the city of Hyderabad with a population of more than 1.5 million people.

Picture credit: Boston.com/Bigpicture/AP photo

Satellite Image and info : NASA/ESO

Leave a Comment August 24, 2010

Meditate And Strengthen Your Brain in 11 Hours

While previous post was on muscles, lets move on to brain now. Meditation which has been practiced in East since ages, is known to relax the practitioner and help him/her have better control over emotions and stressful situations. But it’s also known that it’s not easy to achieve those benefits unless you practice meditation regularly and for sufficient amount of time. But if you practice a form of Chinese meditation called as Integrative-body mind training or IBMT, you might be able to achieve those benefits just after 11 hours of training. In recent study by Michael Posner and Y. Tang (PNAS, Jul 2010), it has been shown that just by 11 hours of IBMT training, positive structural changes were induced in a particular region of the brain which regulates and control our behavior. Anterior Cingulate Cortex (ACC) is that part of the brain which is related to self-regulation and this zone in the brain gets more interconnected as we grow up. In the experiment, it was shown that by 11 hr IBMT training, white matter tract in the brain which connects ACC to other structures of the brain was enhanced resulting in improved efficiency which in turn can result in better self-regulation.

For the experiments, 22 students from Univ of Oregon were given 11 hr IBMT training while 23 students were given simple relaxation training and neuro-imaging technique (diffusion tensor imaging) was used to monitor the fiber connectivity before and after the training. The technique measured something called fractional anisotropy by measuring diffusion of water in the pathway which gives the measure of fiber inter connectivity. The results showed enhanced fiber connectivity in the white matter which increases efficiency of connection between ACC and other parts of the brain. Results from previous studies by the same researchers showed that just after 5 hours of IBMT training , behavioral changes in the form of enhanced attention by students was observed. Also, low stress level was observed. This study further strengthens the positive effects of IBMT meditation and that too achievable in short time of practicing IBMT.

Reference Article: Tang et al., Jul 27 2010, Short-term meditation induces white matter changes in the anterior cingulate, doi: 10.1073/pnas.1011043107

Picture credit: Univ of Oregon Media Relations

Leave a Comment August 24, 2010

Do Muscles Remember Your Strength Training?

What happens to your muscles once you stop going through strength training process? General consensus has been that if you stop going to gym and stop strength training, your muscles will go back to old stage (when you were a lazy bum), and you will lose all the benefits of working out. In order to get back to shape you will have to start all over, that’s what we usually think. Well, behold your thoughts, new study published in PNAS shows that muscles do have some kind of  memory and they retain the memory of the training process you have gone through and so once you decide training process, you will not be starting at zero level. That’s exciting news for people like us, who are not consistent in physical fitness training.The study also states that retraining is facilitated by previous training episode.

So how does muscles retain the memory of previous training it has undergone. Muscle memory is stored as DNA containing nuclei or myonuclei. Muscle cells are very large and one of the few mutli-nuclei cells in vertebrates. Multiple nuclei provides sufficient DNA templates required for sustaining such large muscle cells. When we exercise or work out, muscle cell grows by fusion of muscle cells with stem cells and in the process new nuclei are generated. Earlier it was thought that during atrophy stage (reached after detraining), extra nuclei were destroyed by process called apoptosis. Recent experimental data challenges this idea.

Researchers at Univ of Oslo, Norway used mice to simulate the effect of working out and they used in-vivo imaging technique to observe the changes in mynuclei as the mice worked out their muscles for 21 days. They first observed increase in the myonuclei number during the course of first six days and then they observed increase in mass of the muscle during the rest of the period. In the next step they disconnected the nerve which connected the muscle and thus stimulated the detraining process. They observed that with time, mass of the muscle fiber decreased, as expected, but surprisingly the number of nuclei did not decrease. They observed that that during this process, cells were dying by apoptosis but not the newly formed muscle nuclei. These nuclei survived in the mice for about 3 months which is a long time comparing mice life-time. In humans, this might survive even longer. These surviving nuclei can be easily activated to make proteins for muscles, simply by restarting the training process, and these nuclei remember where you left off!

So, what are the advantages of this new exciting study? Firstly, the experiments and data are beautiful which challenges long held belief and research, it’s exciting scientifically. Secondly, it also suggests that if we work out now and increase these nuclei in our muscles, it might be helpful in our old age when we are unable to create these nuclei in muscles. Earlier we work out, easier to generate these protein synthesizing nuclei and better benefits can be reaped in old age. Thirdly, it also suggests that athletes who use steroids have to rethink their strategy as using steroids increases the number of these nuclei and if this is permanent, then they should be excluded from games forever as they would be getting that unfair advantage even after they stopped using the steroids. Rules of exclusion from games might have to be re-written, just saying sorry for using steroids might not suffice.

Lastly, it’s good news for people like us, we can workout whenever we get time, give a break when get busy, and then restart again when get time and our muscles can pick up from where we left. Good news for lazy bums like me. (Interestingly, this study came out the same week I started going out to gym for strength training, gives me a good excuse to take a break after few weeks).

Reference Article: Bruusgaard et al. Myonuclei acquired by overload exercise precede hypertrophy and are not lost on detraining, doi: 10.1073/pnas.0913935107

First Picture credit: Science News/ J.C. Bruusgaard/University of Oslo: nuclei can be seen as green color on the muscle fiber

Schematic credit: PNAS/ Authors of the article: Previously untrained muscles acquire newly formed nuclei by fusion of satellite cells preceding the hypertrophy. Subsequent detraining leads to atrophy but no loss of myonuclei. The elevated number of nuclei in muscle fibers that had experienced a hypertrophic episode would provide a mechanism for muscle memory, explaining the long-lasting effects of training and the ease with which previously trained individuals are more easily retrained.

Leave a Comment August 24, 2010

Photoemission Delay Time

Photoelectric effect has been known to us for a long time. Heinrich Hertz first observed this phenomena in 1887 where a material absorbs electromagnetic radiation and emits electrons. While most of details are clearly understood, one aspect which has been missing is the delay time in emission of electrons after the matter absorbs photon. If delay exists, does the delay also depend on the energy level from which electron is being emitted? Until now, it was assumed that the photo-emission process is instantaneous. Recent study by researchers at Max Planck Institute of Quantum Optics in Munich, Germany and group of other collaborators , has been able to precisely measure the delay time in photoemission process using ultra-short time measurement technology. They used Neon atoms to study the phenomena. Neon  is more complex than Helium, but it was chosen because Neon is simpler to model theoretically and it also has higher photo-ionization cross-section resulting higher Signal-to-Noise ratio. They found out that that electrons leave 2P level subshell   Formula attoseconds after the electrons have left 2S subshell.  The delaytime of 21 attoseconds between electron emission from 2S and 2P seem to be very small, but it’s an important result as it shows that the process is not instantaneous, as it was assumed until now, and there is certain delay involved possibly due to electron-electron interactions. Scientists also performed complex theoretical computations to calculate the delay time and they came with a delay time 0f 5 attoseconds. The discrepancy can be attributed to multi-electron Neon atom system which makes it very difficult to make accurate theoretical computations. For experiments, two ultrafast laser pulses were used: extreme UV pulse (<200 attosecond duration) was used to eject electrons from 2S and 2P subshells while near infra-red pulse was used for time resolved measurements.

“These to-date poorly understood interactions have a fundamental influence on electron movements in tiniest dimensions, which determine the course of all biological and chemical processes, not to mention the speed of microprocessors, which lie at the heart of computers”, explains Ferenc Krausz, co-author of the study from MPQ. “Our investigations shed light on the electrons’ interactions with one another on atomic scale“. [Attoworld.de Press Release]

The results of the study was published in Science (June 2010, Vol 328, pp 1658) and abstract is as follows:

Delay in Photoemission

Schultze et al.

Vol. 328. no. 5986, pp. 1658 – 1662
DOI: 10.1126/science.1189401

Photoemission from atoms is assumed to occur instantly in response to incident radiation and provides the basis for setting the zero of time in clocking atomic-scale electron motion. We used attosecond metrology to reveal a delay of Formula attoseconds in the emission of electrons liberated from the 2p orbitals of neon atoms with respect to those released from the 2s orbital by the same 100–electron volt light pulse. Small differences in the timing of photoemission from different quantum states provide a probe for modeling many-electron dynamics. Theoretical models refined with the help of attosecond timing metrology may provide insight into electron correlations and allow the setting of the zero of time in atomic-scale chronoscopy with a precision of a few attoseconds.

Photocredit: Attoworld.de Press Release/ MPQ/ LMU/ T. Naeser/ C. Hackenberger

Leave a Comment August 23, 2010

Role of Social Interactions in The Evolution of Migration

Migration of birds, animals, microbial organisms is a very interesting phenomena, much of which is still not clearly understood. In few of my earlier posts, I have mentioned about recent studies focusing on collective migration of birds and how they follow magneto-reception cues to guide them during migration. Other cues which organisms use while migrating can be odor, temperature gradient, concentration gradient etc. In another study, it was shown that the birds follow a pecking order, a kind of hierarchy with a leader and followers while flying long and short distances. Organisms migrate as it gives them certain benefits such as better resource availability, better breeding locations etc but it also involves some cost and organisms try to balance the cost and benefits and these studies try to explain how and why the migration pattern evolves while balancing the costs and benefits. One of the key factors which has not been extensively studied is the role of social interaction between different individuals and how it results in collective migration pattern. Well, that was until now! A recent study by researchers at Princeton University, which is going to be published in the next edition of PNAS, focuses on this key factor. Vishwesha Guttal and Iain Couzin at Princeton have developed a mathematical model which includes social interaction parameter and provides a generic temporal and spatial solution to various collective migration scenarios ranging from zero interaction groups to highly interactive groups. The model is not just limited to birds but can be applied to various organisms from bacteria to wildebeest, that’s the beauty of the model.

So what benefit do organisms get by social interactions? If an organism is error prone in sensing directional cues, then by having a larger group and by interacting with individual members, these errors can be minimized. This is based on principle called ” many wrongs principle” proposed by Bergmann and Donner in 1964 for explaining benefits of group size in animal navigation. By utilizing directional cues and being in group one can take advantage as proposed by many wrongs principle, but utilizing directional cues also incurs some cost. Organism can still enjoy the benefits of being in group even after switching off directional sensing abilities (no cost plus benefits). Ultimately all the members of the group will switch off their directional sensing ability, as there is no incentive to do so, resulting in the whole group losing migration capability. So how does migratory groups evolve a strategy wherein they can use utilize benefits of large group as suggested by “many wrongs principle” and still maintain their direction sensing capabilities. This model by Guttal and Couzin provides answer to such questions in the evolution of migration.

They define two main parameters, ωsi and ωgi, where ωgi is defined as gradient detection ability parameter while ωsi is defined as social trait paramater. ωgi=0 implies random walk by the organism while high ωgi gives high directional accuracy and provides the organism higher velocity in migration, but with high ωgi, comes higher energy related costs. Same with ωsi, higher social interactions comes with higher costs. Fitness of the individuals in the group is obtained by subtracting costs from benefits and thereby an optimum fitness of an individual can be determined. By having various combination of different values of these two parameters, various migration pattern emerges, this study shows. They found that in groups where individuals interact with each other, two modes exist in the optimum solution. One mode consists of individuals which have very high ωgi but very low ωsi, implying they don’t interact much with others but have good directional attributes- these are the leaders. The second mode consists of individuals high on social traits and low on directional traits- these are followers. The study also shows that larger groups require lower proportion of leaders. The paper discusses several other scenarios including effects of habitat destruction on migration pattern and I will recommend you to read the complete paper.

I liked the results of this study alot, not because its my friend’s work, but mostly because I like the simplicity of the model and how nicely it explains various scenarios of migratory pattern and strategies in various organisms. Good work Vishu!!

Here is the abstract of the paper:

Social interactions, information use, and the evolution of collective migration

Vishwesha Guttal and Iain D. Couzin

Abstract

Migration of organisms (or cells) is typically an adaptive response to spatiotemporal variation in resources that requires individuals to detect and respond to long-range and noisy environmental gradients. Many organisms, from wildebeest to bacteria, migrate en masse in a process that can involve a vast number of individuals. Despite the ubiquity of collective migration, and the key function it plays in the ecology of many species, it is still unclear what role social interactions play in the evolution of migratory strategies. Here, we explore the evolution of migratory behavior using an individual-based spatially explicit model that incorporates the costs and benefits of obtaining directional cues from the environment and evolvable social interactions among migrating individuals. We demonstrate that collective migratory strategies evolve under a wide range of ecological scenarios, even when social encounters are rare. Although collective migration appears to be a shared navigational process, populations typically consist of small proportions of individuals actively acquiring directional information from their environment, whereas the majorities use a socially facilitated movement behavior. Because many migratory species face severe threat through anthropogenic influences, we also explore the microevolutionary response of migratory strategies to environmental pressures. We predict a gradual decline of migration due to increasing habitat destruction and argue that much greater restoration is required to recover lost behaviors (i.e., a strong hysteresis effect). Our results provide insights into both the proximate and ultimate factors that underlie evolved migratory behavior in nature. [doi: 10.1073/pnas.1006874107]


Picture credit: Flickr user
rwjensen

Plot credit: Article doi: 10.1073/pnas.1006874107 Video credit: PNAS and authors of the article

Leave a Comment August 22, 2010

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