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Gandhinagar Tuesday, 13 March, 2018 - 17:05

A recent study by researchers from the Department of Environmental Science, Tezpur University, Assam, and the Department of Earth Sciences, Indian Institute of Technology Gandhinagar, Gujarat on the groundwater in the Brahmaputra floodplains has revealed some alarming information. The study has detected the presence of arsenic, uranium and fluorides (compounds of the element fluorine) that can affect the wellbeing of the people in this region.

Arsenic and fluorides are naturally present in the groundwater in several countries across the world. In India, arsenic is found in the groundwater in West Bengal, Assam and other North Eastern states; ‎ fluorides in Andhra Pradesh, Rajasthan, Gujarat and Assam; and uranium in Andhra Pradesh, Jharkhand and Meghalaya. However, this study is the first to measure the co-occurrence of these elements in groundwater in the Brahmaputra floodplains.

The Brahmaputra floodplain has high deposits of alluvium -- material deposited by the river water. Alluvium sediments, rich in minerals, make the low-lying areas close to the banks of the Brahmaputra river very fertile. People living in the state of Assam depend on these regions for agriculture and survival. The researchers carried out a health risk analysis to understand how the exposure to these toxic substances could affect the local people.

There is an absence of data on the state of uranium contamination in the Brahmaputra floodplains and its detection in groundwater could present a more significant threat to the people who inhabit this area, say the authors, in their study published in the journal Chemosphere.

The researchers collected groundwater samples from tube-wells for two years between 2011 and 2012. They also analysed the sediment samples on the floodplain. Using a scanning electron microscope, they determined the the elements present in these samples. They followed guidelines from the USEPA (US Environmental Protection Agency) to carry out a preliminary health risk analysis to determine the risk of cancer and other diseases among people who depend on the drinking water from these areas.

The results of the study showed that most of the groundwater samples contained arsenic and fluoride in low concentrations within the permissible limits recommended by the World Health Organization, except for a few. The researchers found uranium in the sediment samples.

Further analysis showed that children were at the highest health risk due to the exposure to arsenic and fluoride in drinking water, followed by adult males and females. According to the researchers, this could be because children consume more water for their body weight, and since their bodies are still developing, they are more prone to risks. The researchers also point out that children between the age of 3 and 8 years are the most vulnerable.

Studies have shown that arsenic is carcinogenic and drinking water with arsenic concentrations of 50 µg/litre dramatically increases the risk of lung and bladder cancer. Apart from cancer and arsenic poisoning, exposure to arsenic also has adverse effects on a child’s cognitive development. Excess fluoride consumption can cause dental and skeletal fluorosis and affect brain development in children. Although there are no harmful radiation effects from naturally occurring uranium, consuming uranium in large amounts is known to cause kidney diseases.

The study brings out the fact that one of the most fertile floodplains in India could be a health hazard due to the presence of arsenic, uranium and fluorides. With these levels expected to increase in the coming years due to both natural and anthropogenic changes, it is a wake-up call for the authorities to address the issue and nip it at the bud.

Section: General, Science, Health, News Source: Link
Bengaluru Tuesday, 13 March, 2018 - 07:40

In a new study, researchers from the Raman Research Institute (RRI), Bengaluru, present observations about the binary star system ‘LMC X-4' in the neighbouring Large Magellanic Cloud satellite galaxy. Their findings, published in the New Astronomy Journal, uses data from receivers aboard spacecraft XMM-Newton launched by the European Space Agency, and the Rossi X-ray Timing Explorer satellite from NASA. The findings hold important clues in the mechanics behind X-ray emissions seen from this binary system of stars.

The Large Magellanic Cloud (LMC) is a satellite galaxy that orbits our own, much larger, Milky Way. LMC X-4 is a two-star system consisting of a pulsar - a highly magnetised neutron star beaming X-rays - and a companion star. Scientists believe that such pulsars are formed after a supernova explosion, when a dying star spectacularly shoots material and expanding shockwaves into space, before being reborn as a compact star. The neutron stars are so dense that their mass could be twice that of the Sun, with a radius of only 10 kilometres. Its high density makes its magnetic field a trillion times stronger than Earth’s.

In this study, Dr. Aru Beri and Dr. Biswajit Paul from RRI examined characteristics of the X-ray signals emitted from LMC X-4, using signal processing techniques and analysis. The scientists observed three states in the intensity of X-ray emitted by the pulsar: ‘flaring’, ‘persistent emission’, and ‘eclipse’.

Neutron stars evolve through ‘accretion’ - the continuous addition of usually gaseous particles by gravitational attraction. Due to very strong gravitational attraction, the neutron stars accumulate gas in streams from its orbiting companion onto ‘hotspots’ on the surface of the neutron star, which briefly flare with X-rays when the accretion abruptly increases. The ‘flaring state’ of LMC X-4, which happens when there is a sudden increase in the amount of material accreting onto the surface of the neutron star resulting in larger X-ray radiation, showed four distinct flares. These flares exhibit a pattern of pulsation that, when plotted, is broad and sinusoidal in shape. This is followed by a non-flaring or ‘persistent emission state’ where a low signal of X-rays is recorded. The third state of ‘eclipse’ is identified by an absence of X-rays when our view of the neutron star is blocked by its much larger companion.

The researchers focused on the complex structure of the X-ray pulses during the persistent emission state, defined as the region with no flares and no eclipse. They observed ‘dips’ in the pulses during the period of steady, low X-rays, identified by sharp drops in the intensity of radiation. They attribute this to the hotspots becoming obscured by optically dense bands of accreting gas that falls from the companion star into the neutron pulsar star.

The study estimates the timescales involved in the formation of the flares, and the subsequent formation of the accretion column that causes dips, stating that “observed differences in the pulse profiles during and after the flares suggest that significant change in the accretion stream happens during the transition between flares and the persistent state”.

This study takes us a step closer to confirming theories on the nature of light, magnetism, gravity and general relativity. Observing and analysing cosmic phenomena such as pulsars, enables a deeper understanding of some extreme conditions in the cosmos that cannot be created in laboratories. This study gives insight into the behaviour of plasma in extremely high magnetic field and very strong gravity.

The researchers of the study have plans to further their research on X-rays emitted from other stars. “We are currently making an X-ray polarimeter named POLIX, which is the main scientific instrument onboard XPoSat, a satellite mission of ISRO to be launched in 2019, dedicated for investigation of polarisation properties of cosmic X-ray sources”, shares Dr. Paul, about his future plans. Observations with POLIX will allow scientists to determine the magnetic field structure of neutron stars, the key element in the formation of the flares and dips in LMC X-4 that have been discovered with the current investigation.

Section: General, Science, Deep-dive Source:
Bengaluru Monday, 12 March, 2018 - 13:07

In today’s gadget-filled world of cameras, cell phones, smart watches and other lightweight and wearable devices, thin film transistors are commonplace. They are made by stacking thin layers of semiconductors, insulators and metals. In a study published in Nature’s Scientific Reports, researchers from the Indian Institute of Science, Bengaluru, have explored how creating textures in metal films used in such transistors could help make them easy to control.

Transistors are building blocks in any electronic circuit. Circuit engineers design various types of transistors by making modifications to their structure and their functional properties. One such property is the amount of output current produced, for each unit input voltage supplied. This property is called transconductance. Increase in transconductance is possible by changing the aspect ratio of the device, but it increases the area and thus the space occupied and also the unwanted capacitance. The researchers of the study have proposed a modification in manufacturing the device that can control transconductance and also keep unwanted capacitance in control.

A thin film transistor is fabricated by depositing thin layers on metal (called gate), insulator and semiconductor on an insulator surface, most commonly glass. The researchers of the study suggest creating parallel ridges or corrugations in the metal layer. This modification, they claim, can help control the transistor properties without increasing its size. Corrugations change the length and the properties of the channel through which the current flows. Corrugations or texturing could be made parallel to  the direction of flow of current or perpendicular to it or the angle could be varying continuously between these values. The gate metal is deposited in two stages, the first stage is a planar layer and the second achieves the desired texturing. 

The scientists studied the effects of corrugations using simulations and experiments. They found that the transconductance increased when corrugations were along the direction of flow of the current, and gradually decreased as the angle of corrugations became perpendicular to the flow of current. They also observed and measured the current-voltage characteristics, capacitance and the minimum voltage at which the transistor begins conducting, for transistors fabricated with a corrugated gate.

The study demonstrates that corrugations can be used as a method to control transistor parameters in addition to changing the aspect ratio or the input voltage. A smooth control over flow of current is possible by controlling the angle of the corrugations. This technique can be used to improve the gain of amplifiers without changing the layout area.

Section: General, Science, Technology, News Source: Link
Bengaluru Monday, 12 March, 2018 - 07:28

In research to be shared at the prestigious 56th International Reliability Physics Symposium (IRPS), researchers from the Indian Institute of Science Bangalore (IISc)  will present a paper that details a breakthrough in significantly improving the reliability limits of 3D FinFET technology in sub-14nm technology for System-on-Chip integration. The study is the result of work in collaboration with Intel that sought to better understand various aspects of electrostatic discharge (ESD), latch-up and hot carrier reliability of ultra-dense FinFET technologies. The team reached a significant milestone in understanding the fundamental knobs dictating various degradation and failure modes. The symposium is held in San Francisco, USA

The research also explores new possibilities of integrating high voltage functionalities in FinFET nodes. Making the FinFET devices to work in a narrow operating window or working at smaller voltages is less challenging than making them work under extended conditions with various reliability threats or operating them at higher voltages, for eventual integration in System on Chips (SoC).

Prof. Mayank Shrivastava, who is leading this effort at IISc Bangalore explained that “For system on chip (SoC) integration, besides low voltage functionalities, you need highly reliable devices capable of handling higher voltage and special ESD protection devices. For instance, the logic, memory and computational blocks in the SoCs can be implemented using sub-1V devices. However one may need 1.8V or 3.3V devices to interface the chips with the external world, which are called Input / Output (I/O) devices. Similarly, one requires 5V or 10V high voltage FinFET devices (often known as LDMOS) to develop power management modules as well as integrated RF power amplifiers. Beside various functional devices, SoC integration requires special ESD protection devices and additional ruggedisation of functional devices.”     

Prof. Shrivastava says this achievement of enhancing reliability limits of ultra-dense FinFETs and inventing special ESD protection and high voltage devices for the same is a breakthrough. Through the research, the electrical engineers were able to explain the mechanisms behind ESD, latch-up and hot carrier reliability in FinFET devices. Weak ESD robustness against exposure to high ESD stress at the end-user side had been a roadblock for the construction of high voltage interfaces and SoC integration in 3D FinFET nodes. The insight into the physics of the various device reliability and high voltage operation now allows the development of highly rugged devices. This is a significant milestone regarding enabling FinFET technology for SoC integration.

The Ph.D. students supported by Intel under this collaboration at IISc Bangalore, are Milova Paul and B. Sampath Kumar. Dr. Harald Gossner, a senior principal engineer at Intel, was involved in the research activity and called it one of finest examples of academia-industry interaction which has resulted in substantial value addition to the two collaborating partners.

Shrivastava said that this collaboration has been beneficial in exposing students to challenging real-world industry problems, and has provided them with a chance to closely interact with one of the world's largest semiconductor company. "Though we have been interacting with many semiconductor industries, this interaction with Intel is particularly different because of the immense trust Intel had in our capabilities and the information as well as mentorship that they were willing to share. Since the industries in the semiconductor business survive on their intellectual property (IP), it was important for us to realise the value of IP, and we sometimes had to go that extra mile in educating our students specifically on these aspects. We are happy that this interaction between IISc Bangalore & Intel is turning out to be a win-win situation for both the parties involved, which has resulted into several key IPs and series of high-value publications", Prof. Shrivastava stated.

Those interested can hear the presentation by attending the symposium March 11-15 at the San Francisco Airport Hyatt Regency.

Section: General, Science, Technology, Engineering, News Source:
Mumbai Friday, 9 March, 2018 - 16:12

Ever wondered why the great cities of India like Mumbai and Chennai frequently make headlines for flood-related disasters? Researchers from the Indian Institute of Technology Bombay, have an answer for you. In a study published in Nature, the researchers have proved that the pattern of urbanisation, including buildings and roads, intensifies extreme rainfall.  The study also demonstrates that urbanisation considerably increases the variations in the intensity of rain at different locations in a city.

As per a report by the United Nations, the urban population in India is expected to touch 800 million by 2050, a hundred percent increase from its current values. Cities will continue to grow vertically and spatially, and climate change adds to the woes. The result? Increase in the frequency of extreme weather events that affect the urban society, economy, and infrastructure.

Previous studies have shown that the increase in concretisation, due to buildings and other structures, leads to lower runoff of the rainwater and causes floods in the cities. However, the impact of the pattern of urbanisation on rainfall was not clear. While studies based on satellite data showed that urbanisation intensifies rainfall, the data from weather stations could not support this. The researchers of this study have considered data from 55 different automatic weather stations to support the hypothesis that urbanisation does have an impact on extreme rainfall events.

The researchers attribute this phenomenon to ‘urban heat islands’ formed due to changes in the land cover, urban emissions that amplifies cloud condensation, and buildings that obstruct the atmospheric motion. In addition to the urbanisation, the pattern of urbanisation was also found to increase these impacts on rainfall as different urban structures affect the energy balance at the surface, as well as the atmosphere. In addition, the study highlights that the intensification of precipitation is not uniform, and is prominent in a few parts of the city, and depends on building canopies, heat sources, and road networks.

The researchers suggest localised monitoring and radar datasets as the most effective methods to study the impact of urbanisation on rainfall rather than weather stations which may not be able to capture all the local variations in rainfall pattern.

So the next time your city floods, stop looking at the clouds and start looking at the skyscraper instead.

Section: General, Science, Society, News Source: Link
Bengaluru Friday, 9 March, 2018 - 07:48

Roald Dahl’s famous book ‘James and the Giant Peach’ is a story of a boy named James, who, to escape his cruel aunts, takes up residence inside a giant, magical peach. Inside this fruit, he ends up having many wonderful adventures with a grasshopper, a centipede, an earthworm, a spider, a ladybug, and a glowworm -- all of them living inside the same peach! While one may dismiss this as a fantasy or a ‘bedtime’ story, many young fig wasps live a life of James, albeit inside a fig!

In a recent study, published in the journal Movement Ecology, researchers at the Indian Institute of Science, Bengaluru, have uncovered some hitherto unknown, exciting aspects about fig-wasps and the journey they take to lay their eggs. “Fig wasp communities are fantastic for a lot of reasons, especially since they are in such a close and intimate association with their host plant,” says Vignesh Venkateswaran, the lead author of the study.

Pollinating fig wasps and fig trees share an extraordinary special relationship where both benefit from each other. The female pollinating wasps enter the syconia –  the inflorescence of the fig, pollinate and lay their eggs in the syconia. Once done, their offspring develop and upon reaching adulthood, fly out with pollen clinging to them to repeat the cycle. When these wasps enter another syconium, they pollinate them. Fig wasp communities also consist of non-pollinating wasp species.This study investigated a community of seven wasp species of which only one species pollinates the fig.. The other six species are essentially cheaters in the system; making use of the fig to lay eggs without offering any service in return. And as for the eggs, they safely hatch and grow into adults, feeding on the fig, away from the eyes of their predators. This relationship can get so specific that the wasps of a specific species will only lay eggs in a syconium which is in precisely the right stage of development.

Apart from the obligate relationship, another fascinating aspect of fig wasps is the journey they take from their ‘home’ tree where they reside (natal tree) to the trees where they lay their eggs (resource tree). Though we know that each species of the fig wasp has its own window of time to lay its eggs, called an oviposition window, not much is known about the journey yet -- an aspect the researchers of the study are trying to bring out. “These trees can be away from each other by as much as 100 km or more, and these 2mm wasps have to fly such long distances in very short times, to survive and reproduce. Though fig wasps are expected to be excellent at flying and dispersing long distances, no study has ever attempted to characterise their ability to move,” shares Vignesh Venkateswaran.

The primary constraint in the journey of female wasps is the very short window in which they have to lay their eggs. Since all figs in their natal tree, where they are born, are in the same developmental stage and ripen once the adult wasps are released, the wasps now need to look for younger syconia to lay their eggs. “Wasps have to fly away to find other trees. But since each wasp is looking for a fig in a particular developmental stage, they are searching for different trees,” points out Vignesh.

Previous studies have shown that wind disperses female wasps from their natal syconium. In fact, the wasp species Ceratosolen arabicus can be wind-scattered over 160 km in its one-day adult lifespan! In this arduous journey, what role do wasps play in channelising their movement? The researchers tested the flight duration, energy reserves and resting metabolic rates of seven wasp species – five short-lived species and two with longer lifespans –  to decipher this.

“Each species has a specific oviposition window length. Imagine a wasp that has an oviposition window of only two days and another which has an oviposition window of 16 days. For the first wasp, the figs last for a short period in that stage. This short window would mean that there are fewer trees that have that stage of fig; fig trees transition through this stage quickly.  On the other hand, for a wasp that has an oviposition window of 16 days, the figs last for a very long time serving as a resource. The wasp can, during any of the 16 days, lay its eggs.  In simple terms, there will be eight times as many trees in any instance for the second wasp, compared to the first”, explains Vignesh  Venkateswaran.

The researchers found that all three traits –  flight duration, energy reserves and resting metabolic rates –  were higher in short-lived species as compared to the long-lived ones. This finding is significant as wasps with a short lifespan, generally tend to have smaller windows of opportunity to lay eggs and hence, need to traverse longer distances in search of syconia in the right stage of development. The study demonstrates, for the first time, that the developmental stage of the syconium influences the insect’s dispersal capacities. The results of the investigation also suggests that these traits are inherited across generations and strengthened by natural selection.

The study gives a new perspective on what could lead to differences in movement abilities of each species of a single community, and what could be the evolutionary forces that make them move the way they do. Besides, studies on these tiny wasps help throw some light into the fragile lives of figs and fig wasps. “Figs are important life-lines for animals in tropical forests. Each kind of fig has its own unique wasp community. The future of both is uncertain now due to rapid deforestation,” remarks Vignesh.

The researchers now plan to understand this complicated process of fig wasp movements with more hypotheses and modelling. “We are investigating dispersal of multiple fig wasp communities and testing some of our hypotheses. We are also modelling the minimum number of trees that may be required to enable the persistence of wasp communities,” signs off Vignesh Venkateswaran.  

Section: General, Science, Ecology, Deep-dive Source:
Kharagpur Thursday, 8 March, 2018 - 15:40

Scientists from Indian Institute of Technology Kharagpur (IIT Kgp) and GLA University, Mathura have developed a novel, low power humidity sensor using molybdenum disulphide nanoflakes and platinum nanocrystals.

Humidity refers to the amount of water vapour in the atmosphere. A high percentage water vapour in the atmosphere can be detrimental to our electronic devices, causing corrosion and damaging the device, and our infrastructure by causing mould damage. And, as humans cool-off through perspiration or sweating, high humidity can also upset the rate at which sweat evaporates affecting the body’s temperature control. Detecting high levels of humidity is a priority for comfortable living.

In the new study, researchers developed few-layered Molybdenum Disulphide (MoS2) decorated with platinum nanoparticles (PtNPs) to function as a low power, highly sensitive humidity sensor. Bulk powder of MoS2 was mixed with an appropriate solvent and then exfoliated to form the nanoflakes. Next, chloroplatinic acid hexahydrate were reduced to Pt NPs using a novel reduction technique using sulphide salt, to fabricate the Pt/MoS2 composite structure. The structure of the composite formed was confirmed to be that of MoS2 decorated with Pt nanoparticles, using various material characterization tools like scanning electron microscopy, atomic force microscopy, transmission electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, Raman spectroscopy and UV–visible spectroscopy.

To check their performance as a humidity sensor, the Pt/Mos2 composites were drop coated onto gold interdigitated electrodes to form a humidity sensor. The sensor was then exposed to various levels of relative humidity. The team fabricated composites with different amounts of Pt nanoparticles coating the MoS2 nanoflakes, to arrive at an ideal composition which could accurately measure the humidity, while remaining robust and efficient.

The results show, a mixing ratio of 0.25:1 of Pt NPs to MoS2 had the best response of all the samples measured. The response and recovery time of the newly developed sensor was also measured, and found to be around 92s and 154s respectively, indicating the sensor could make continuous observations, without much break between each measurement. The researchers further went on to explain the working of the sensor and the sensing mechanism. The low power consumption, response and recovery times, and the high efficiency of the device make it ideal for mass deployment for humidity measurements.

Section: General, Science, Engineering, News Source:
Bengaluru Thursday, 8 March, 2018 - 07:50

Cancer, the silent killer, comes in various types and forms. One of them is the head and neck cancer -- a group of cancers that start within the mouth, nose, throat, larynx, sinuses or salivary glands. It is the most commonly diagnosed cancer worldwide, and about 90% of all head and neck cancers are squamous cell carcinomas (HNSCC), says a report from the World Health Organization. Squamous cell carcinoma is an uncontrolled growth of abnormal cells arising in the squamous cells, which compose most of the skin’s upper layers.

Studies show that in India, people from the northeastern states--Assam, Manipur, Mizoram, Tripura and Nagaland -- have the highest incidence of head and neck cancers in the country. Now, a study by researchers from the Assam University, University of Science and Technology, Meghalaya; University of Kalyani, and the Institute of Advanced Study in Science and Technology, Guwahati, explores some of the reasons behind this observation. The study, published in Tumor Biology: Journal International Society for Oncology and Biomarkers, also suggest biomarkers for early, efficient and comprehensive diagnosis of HNSCC.

The researchers collected data from 50 healthy individuals and 50 individuals suffering from head and neck cancers about their age group, gender, lifestyle and tobacco-consumption habits. They then analysed this data and found that lifestyle and tobacco-consumption habits played a significant role in the incidence of cancer.

“The practice of betel quid chewing, primarily consumed with betel leaf and slaked lime, along with using smokeless tobacco products (khaini, zarda and gutkha) and cigarette smoking, contribute to the risk of HNSCC in these states. Also, using a kitchen with minimal ventilation and continuous exposure to household smoke from burning firewood plays a big role", says Dr. Rosy Mondal, a scientist at the Institute of Advanced Study in Science and Technology, Guwahati, and an author of the study.

For the study, the researchers also isolated ‘cell-free mitochondrial DNA’ from the blood plasma of the two study groups -- one that had healthy individuals, and the other with those who suffered from HNSCC. “Cell-free mitochondrial DNA is the freely circulating mitochondrial DNA. They are also referred to as cell-free DNA because they are not present inside the cell, rather circulate freely in the bloodstream”, explains Dr. Mondal.

The researchers then studied the relationship between the content of mitochondrial cell-free DNA, the nuclear DNA present in the cells, with the habit of using quid chewing, smoke and smokeless tobacco. It was done to establish the potential use of these DNAs as an early diagnostic marker. The results showed that there was a significant difference in the level of the cell-free DNA between HNSCC cases and control.

So what are the benefits of using cell-free DNA as a biomarker for detecting cancer? “The presence of certain changes in a tissue obtained invasively, via biopsy, for example, are considered biomarkers in cancer. These biomarkers could show some abnormality, or it could show the presence or absence of a membrane receptor, which could indicate cancer. Cell-free DNA acts as a non-invasive analysis of tumour-derived genetic material”, explains Dr. Mondal. “A non-invasive biomarker is simply one that can be obtained easily and without ‘harming’ the patient. It could lead to efficient screening and comprehensive monitoring of HNSCC, which could be very beneficial for the management of the corresponding disease burden in the states of northeast India”, she adds.

This study is the first of its kind that relates the increased cell-free mitochondrial DNA content in patients with HNSCC, to the habits of betel quid chewing, using smoke and smokeless tobacco, and other lifestyle habits. The study also shows the likely use of cell-free DNA as a non-invasive biomarker in detecting cancer early on.

Section: General, Science, Health, Society, Deep-dive Source:
Delhi Wednesday, 7 March, 2018 - 14:29

The Western Ghats in India and Sri Lanka are well known biodiversity hotspots, with a rich diversity of amphibian species. Both these regions have high density of amphibian endemism, which means that many of the species of amphibians found here are found nowhere else on Earth. Over 85% of amphibian species found in Sri Lanka are endemic, making this island nation have the highest amphibian endemism in Asia.

A collaborative effort by researchers from the University of Delhi, India, University of Peradeniya, Sri Lanka, University of Sri Jayewardenepura, Sri Lanka, Savitribai Phule Pune University, India, Zoological Survey of India, India, University of Kelaniya, Sri Lanka and Guangxi University, China has led to a new species of frog-- Uperodon rohani or Rohan’s globular frog being described from Sri Lanka. The new species was revealed during the revision of the South Asian species of frogs in the Uperodon genus using an integrative taxonomic approach, which uses a combination of morphological studies and DNA bar-coding. The study was published in the prestigious Zootaxa journal.

Currently, there are 12 known species in the South Asian genus of globular frogs, most of which are largely found in India and Sri Lanka. In this study, the researchers reviewed the taxonomy of all the species in this genus and studied their distribution, calling pattern, breeding behaviour, and physical characteristics of adults and tadpoles. Data for the research was collected from the Western Ghats - Sri Lanka biodiversity hotspot, between 2002 and 2015.

Speaking about the new discovery, the researchers say that this species was widely mistaken to be the Indian species Uperodon variegatus. DNA analysis and morphological comparisons showed that the species in Sri Lanka is indeed a distinct species, and was named U. rohani. It was named after taxonomist Rohan Pethiyagoda, for his extensive contribution to biodiversity research on amphibians and fish in Sri Lanka.

U. rohani is endemic to Sri Lanka and is distributed across the country. According to the researchers, it is very closely related to U. variegatus with similar physical and genetic characteristics. However, they can be differentiated by certain physical characteristics such as: the snout length of U. rohani is almost the same as the diameter of its eye whereas the snout length of U. variegatus is relatively longer than its eye; and U. rohani’s head is relatively narrower as compared to the relatively wider head of U. variegatus.

In the last decade alone, over 160 species of frogs have been discovered from the Western Ghats - Sri Lanka biodiversity hotspot. With increase in amphibian research in this region and the advancement of taxonomic techniques and tools, our understanding of amphibian classification and nomenclature is fast improving.
 

Section: General, Science, Ecology, News Source: Link
Bengaluru Wednesday, 7 March, 2018 - 09:30

ವಯಸ್ಸು ಹೆಚ್ಚಾಗುತ್ತಾ ಸಾಗಿದಾಗ, ಸ್ಮರಣೆಯು ಇಳಿಜಾರಿನ ಕಡೆಗೆ ಹೊರಳಲು ಆರಂಭಿಸುತ್ತದೆ. ಆದರೆ, ಬದುಕಿನ ಅತ್ಯಂತ ಮೂಲಭೂತ ವಿಷಯಗಳನ್ನೇ ಮರೆತುಬಿಡೋದಂದ್ರೆ ಸುಮ್ಮನೇಯೇ? ತಿನ್ನುವುದು, ಮಾತನಾಡುವುದು, ಕುಟುಂಬದ ಸದಸ್ಯರ ಹೆಸರುಗಳನ್ನೇ ಮರೆಯುವಷ್ಟು ಸ್ಮರಣೆಯ ಸಮಸ್ಯೆ ಉಂಟಾದರೆ ಆ ಸ್ಥಿತಿಯನ್ನು ಬಹಳ ಗಂಭೀರವಾದ ಮಾನಸಿಕ ವ್ಯಾಧಿ ಎಂದು ಪರಿಗಣಿಸಲಾಗುತ್ತದೆ. ಈ ಗಂಭೀರ ಮರೆಗುಳಿತನದ ಅತ್ಯಂತ ಸಾಮಾನ್ಯ ವಿಧ-ಆಲ್ಝೈಮರ್ನ ಖಾಯಿಲೆ. ಇದು ಚಿಕಿತ್ಸೆ ಇಲ್ಲದ ಒಂದು ರೋಗವಾಗಿದ್ದು, ಸುಮಾರು ೧.೬ ದಶಲಕ್ಷ ಹಿರಿಯರು ಅಲ್ಝೈಮರ್ನೊಂದಿಗೆ ಬಳಲುತ್ತಿದ್ದಾರೆ; ಈ ರೋಗವನ್ನು ಸಂಪೂರ್ಣವಾಗಿ ಗುಣಪಡಿಸಲು ಸಾಧ್ಯವಿಲ್ಲದಿದ್ದರೂ, ಮೊದಲ ಹಂತಗಳಲ್ಲೇ ಪತ್ತೆಹಚ್ಚಲು ಸಾದ್ಯವಾದರೆ, ಸೂಕ್ತ ಔಷಧೋಪಚಾರದ ಸಹಾಯದಿಂದ ತಕ್ಕಮಟ್ಟಿಗೆ ಈ ರೋಗದ ಉಪಟಳವನ್ನುಸಹಿಸಿಕೊಳ್ಳಬಹುದು ಅಲ್ಲವೇ? ಅದೇ ನಿಟ್ಟಿನಲ್ಲಿ ಬೆಂಗಳೂರಿನ ಭಾರತೀಯ ವಿಜ್ಞಾನ ಸಂಸ್ಥೆಯ ಸಂಶೋಧಕರು ಸಂಶೋಧನೆ ಕೈಗೊಂಡಿದ್ದು, ಅವರ ಅಧ್ಯಯನವು ಈ ದಿಕ್ಕಿನಲ್ಲಿ ಹೊಸ ಒಳನೋಟಗಳನ್ನು ತೆರೆದಿಟ್ಟಿದೆ.

೧೯೦೬ರಲ್ಲಿ ಡಾ. ಅಲೋಯಿಸ್ ಆಲ್ಝೈಮರ್ ಅವರಿಂದ ವಿವರಿಸಲ್ಪಟ್ಟ ಆಲ್ಝೈಮರ್ನ ಖಾಯಿಲೆಗೆ, ಒಂದು ಶತಮಾನದ ನಂತರವೂ ವಿಜ್ಞಾನಿಗಳು ಇನ್ನೂ ಚಿಕಿತ್ಸೆಗಾಗಿ ಹುಡುಕಾಟ ನಡೆಸಿದ್ದಾರೆ; ಆದರೆ, ಮೆದುಳಿನಲ್ಲಿ ಕಂಡುಬರುವ ಅಸಹಜತೆಯನ್ನು ಜೀವಕೊಶೀಯ ಮತ್ತು ಆನುವಂಶಿಕ ನೆಲೆಗಟ್ಟಿನಲ್ಲಿ ಅರ್ಥೈಸಿಕೊಳ್ಳುವ ಮಟ್ಟದಲ್ಲಿ ವಿಜ್ಞಾನ ಕ್ಷೇತ್ರ ಮುಂದುವರೆದಿರುವುದು, ಹೊಸ ಭರವಸೆ ನೀಡುತ್ತದೆ. "ಆಲ್ಝೈಮರ್ನ ರೋಗದಲ್ಲಿ ಕಣ್ಣಿಗೆ ಕಾಣುವಂತೆ ರೋಗಲಕ್ಷಣಗಳು ಗೋಚರಿಸುವುದಕ್ಕೂ ಕನಿಷ್ಠ ಎರಡು ದಶಕಗಳ ಮೊದಲೇ, ಆಣ್ವಿಕ ಮಟ್ಟದಲ್ಲಿ ಬದಲಾವಣೆ ಪ್ರಾರಂಭವಾಗಿರುತ್ತದೆ ಎಂದು ವಿಶ್ವದಾದ್ಯಂತ ಸಂಶೋಧನೆ ಬಹಿರಂಗಪಡಿಸಿದೆ" ಎನ್ನುತ್ತಾರೆ ಈ ಅಧ್ಯಯನವನ್ನು ಮುನ್ನಡೆಸಿದ ಪ್ರೊಫೆಸರ್ ವಿಜಯಲಕ್ಷ್ಮಿ ರವೀಂದ್ರನಾಥ್.

'ದಿ ಜರ್ನಲ್ ಆಫ್ ನ್ಯೂರೋಸೈನ್ಸ್'ನಲ್ಲಿ ಪ್ರಕಟವಾದ ಈ ಅಧ್ಯಯನದಲ್ಲಿ, ಸಂಶೋಧಕರು ಮೊದಲ ಬಾರಿಗೆ, ಒಂದು ಬಗೆಯ ಕೋಶಕವಚೀಯ ಪ್ರೊಟೀನ್ನ ನಷ್ಟವು, ಆಲ್ಝೈಮರ್ನ ಕಾಯಿಲೆಯಲ್ಲಿ ಕಂಡುಬರುವ ಅರಿವಿನ ಅಸಮರ್ಪಕತೆಗೆ ಕಾರಣ ಎಂದು ತೋರಿಸಿದ್ದಾರೆ. "ಆಲ್ಝೈಮರ್ ರೋಗದ ಪ್ರಗತಿಯ ಅವಧಿಯಲ್ಲಿ, ಅಣುಗಳ ಬದಲಾವಣೆಗಳು ಎಷ್ಟು ಶೀಘ್ರದಲ್ಲಿ ಸಂಭವಿಸುತ್ತವೆ ಎಂದು ನಾವು ಕಂಡುಕೊಳ್ಳಲು ಪ್ರಯತ್ನಿಸಿದ್ದೇವೆ. ಈ ಬದಲಾವಣೆಗಳ ಬಗೆಗಿನ ಜ್ಞಾನವನ್ನು ಮೊದಲ ಹಂತಗಳಲ್ಲಿ ಬೇಕಾಗುವ ರೋಗನಿರ್ಣಯ ಪರೀಕ್ಷೆಗಳನ್ನು ಅಭಿವೃದ್ಧಿಪಡಿಸಲು ಬಳಸಲಾಗುವುದು" ಎನ್ನುತ್ತಾರೆ ಡಾ. ವಿಜಯಲಕ್ಷ್ಮಿ

ಮೆದುಳನ್ನೂ ಸೇರಿದಂತೆ, ನಮ್ಮ ನರಮಂಡಲವು 'ನ್ಯೂರಾನ್' ಅಥವಾ 'ನರಕೋಶಿಕೆ' ಎಂಬ ೧೦೦ ಶತಕೋಟಿ ನರಕೋಶಗಳಿಂದ ಮಾಡಲ್ಪಟ್ಟಿದೆ; ಈ ಪ್ರತಿಯೊಂದು ನರಕೋಶವೂ ಜೀವಕೋಶೀಯ ದೇಹವನ್ನು, 'ಅಕ್ಸಾನ್' ಎಂಬ ಉದ್ದನೆಯ ಬಾಲದಂಥ ರಚನೆಯನ್ನು ಮತ್ತು 'ಡೆಂಡ್ರೈಟ್' ಎಂಬ ರೆಂಬೆಕೊಂಬೆಗಳಂತೆ ಹರಡಿಕೊಂಡಿರುವ ರಚನೆಗಳನ್ನು ಹೊಂದಿರುತ್ತದೆ. ಈ ಡೆಂಡ್ರೈಟ್ಗಳು ಅಂದರೆ ನರಕವಲುಗಳು, ನೆರೆಹೊರೆಯ ನರಕೋಶಿಕೆಗಳ ಆಕ್ಸಾನ್ಗಳಿಂದ ಮಾಹಿತಿಯನ್ನು ಸಂಗ್ರಹಿಸುತ್ತವೆ. ಈ ನರಕವಲುಗಳಿಂದ ಹೊರಬಂದಿರುವ ಸಣ್ಣ ಮುಂಚಾಚುವಿಕೆಗಳೇ, ಮಾಹಿತಿ ಪಡೆಯುವ ಕೇಂದ್ರಗಳು. ಅವು ಪ್ರಾಥಮಿಕವಾಗಿ 'ಆಕ್ಟಿನ್' ಎಂಬ ಕೋಶಕವಚೀಯ ಪ್ರೊಟೀನ್ನ ಮೂಲಕ ಕಾರ್ಯನಿರ್ವಹಿಸುತ್ತವೆ.

ನರಕೋಶಿಕೆಗಳಲ್ಲಿ, ಆಕ್ಟಿನ್ ಎಂಬ ಈ ಬಹುಮುಖ್ಯ ಪ್ರೋಟೀನ್ ಗ್ಲೋಬುಲರ್ ಆಕ್ಟಿನ್ (ಜಿ-ಆಕ್ಟಿನ್) ಮತ್ತು ಫಿಲಮೆಂಟಸ್ ಆಕ್ಟಿನ್ (ಎಫ್-ಆಕ್ಟಿನ್) ಎಂಬ ಎರಡು ಸ್ಥಿತಿಗಳಲ್ಲಿ ಅಸ್ತಿತ್ವದಲ್ಲಿದೆ. ತಂತು ಆಕಾರದ ಎಫ್-ಆಕ್ಟಿನ್ ಪ್ರೋಟೀನ್ನ ಕೆಲಸ, ನರಕವಲುಗಳ ಮುಂಚಾಚುವಿಕೆಯ ಸ್ವರೂಪವನ್ನು ಮತ್ತು ಸ್ಮರಣೆಯನ್ನು ಕಾಪಾಡಿಕೊಳ್ಳುದು. ಅನೇಕ ಜಿ-ಆಕ್ಟಿನ್ ಪ್ರೂಟೀನ್ ಅಣುಗಳು ಸೇರಿ ಎಫ್-ಆಕ್ಟಿನ್ನನ್ನು ರೂಪಿಸುತ್ತವೆ. ಹೆಚ್ಚು ಎಫ್-ಆಕ್ಟಿನ್ ಅಣುಗಳಿದ್ದರೆ ಮಿದುಳಿನ ಚಟುವಟಿಕೆಯು ಉತ್ತಮವಾಗಿರುತ್ತದೆ ಎಂದು ಅಧ್ಯಯನಗಳು ತೋರಿಸಿವೆ. ಆದ್ದರಿಂದ, ನರಕೋಶಗಳಲ್ಲಿ ಈ ಎರಡೂ ಪ್ರೋಟೀನ್ ಅಣುಗಳ ಆರೋಗ್ಯಕರ ಸಂಖ್ಯೆಯನ್ನು ಕಾಪಾಡಿಕೊಳ್ಳುವುದು ಡೆಂಡ್ರೈಟ್ಗಳ ಕಾರ್ಯನಿರ್ವಹಣೆಯಲ್ಲಿ ಪ್ರಮುಖ ಪಾತ್ರ ವಹಿಸುತ್ತದೆ. ಈ ಅಧ್ಯಯನದ ಮೂಲಕ, ಎಫ್-ಆಕ್ಟಿನ್ ಪ್ರೋಟೀನ್ನ ನಷ್ಟವು, ಆಲ್ಝೈಮರ್ ಖಾಯಿಲೆಗೆ ಕಾರಣವಾಗಬಹುದೆಂದು ಸಂಶೋಧಕರು ಕಂಡುಕೊಂಡಿದ್ದಾರೆ.

ಸಂಶೋಧಕರು, ಇಲಿಗಳ ಮೆದುಳಿನ ಜೀವಕೋಶಗಳಲ್ಲಿ ಮತ್ತು ಆಲ್ಝೈಮರ್ನಿಂದ ಬಳಲುತ್ತಿರುವ ಮನುಷ್ಯರ ಮೆದುಳಿನಲ್ಲಿ ಎಫ್-ಅಕ್ಟಿನ್ ಮತ್ತು ಜಿ-ಆಕ್ಟಿನ್ ಮಟ್ಟವನ್ನು ಅಧ್ಯಯನ ಮಾಡಿದರು. ಅವರು ಎಫ್-ಅಕ್ಟಿನ್ ಅಣುಗಳ ರಚನೆ ಮತ್ತು ಸಂಯೋಜನೆಯಲ್ಲಿನ ಬದಲಾವಣೆಯನ್ನು ತನಿಖೆ ಮಾಡಲು, ಜೀವರಾಸಾಯನಿಕ ಮತ್ತು ನಡವಳಿಕೆಯ ಪ್ರಯೋಗಗಳನ್ನು ನಡೆಸಿದರು ಮತ್ತು ಇದರ ಪರಿಣಾಮವಾಗಿ ಆಗುವ ಬದಲಾವಣೆಗಳು ನೇರವಾಗಿ ಸ್ಮರಣಶಕ್ತಿಯ ಮೇಲೆ ಪರಿಣಾಮ ಬೀರಿದೆಯೇ ಎಂದು ಕೂಲಂಕುಷವಾಗಿ ಗಮನಿಸಿದರು. ಒಂದು ವಿಶೇಷ ಬಗೆಯ ಸೂಕ್ಷ್ಮದರ್ಶಕವು ನರಕೋಶಗಳಲ್ಲಿನ ಎಫ್-ಆಕ್ಟಿನ್ನ ತೀವ್ರತರವಾದ ವಿಘಟನೆಯನ್ನು ವೀಕ್ಷಿಸಲು ವಿಜ್ಞಾನಿಗಳಿಗೆ ಸಹಾಯ ಮಾಡಿತು.

ಇಲಿಗಳ ಮೆದುಳಿನ ಜೀವಕೋಶಗಳಲ್ಲಿ, ಎಫ್-ಆಕ್ಟಿನ್ ವಿಭಜನೆಯಾದಾಗ, ನರಕವಲುಗಳ ಮುಂಚಾಚುವಿಕೆಯ ವಾಸ್ತುಶಿಲ್ಪವೇ ಬದಲಾಯಿತು ಎಂದು ಫಲಿತಾಂಶಗಳು ತೋರಿಸಿಕೊಟ್ಟವು. ಅಲ್ಝೈಮರ್ನ ಲಕ್ಷಣಗಳು ಸಾಮಾನ್ಯವಾಗಿ ಏಳು ಅಥವಾ ಒಂಬತ್ತು ತಿಂಗಳ ನಂತರ ಕಾಣಿಸಿಕೊಳ್ಳುತ್ತವೆ; ಆದರೆ ಇಲ್ಲಿ ಒಂದು ತಿಂಗಳಿನಲ್ಲೇ ಬದಲಾವಣೆ ಕಂಡುಬಂತು. ಎಫ್-ಆಕ್ಟಿನ್ನ ವಿಭಜನೆಯನ್ನು ನಿಲ್ಲಿಸಲು ಸಂಶೋಧಕರು ಸ್ಥಿರವಾದ ರಾಸಾಯನಿಕವನ್ನು ಬಳಸಿದಾಗ, ಧನಾತ್ಮಕ ಫಲಿತಾಂಶವೂ ಕಂಡುಬಂತು. ಹಾಗೆಯೇ, ಎಫ್-ಆಕ್ಟಿನ್ನ ವಿಭಜನೆಯನ್ನು ಹೆಚ್ಚಿಸಲು ರಾಸಾಯನಿಕವನ್ನು ಬಳಸಿದಾಗ, ಇಲಿಗಳ ವರ್ತನೆಯಲ್ಲಿ ಆಲ್ಝೈಮರ್ನ ಗುಣಲಕ್ಷಣಗಳು ಕಂಡುಬಂತು ಎಂದು ಸಂಶೋಧಕರು ಗಮನಿಸಿದ್ದಾರೆ.

ಸಾಮಾನ್ಯ ಮನುಷ್ಯರ ಮೆದುಳಿನಲ್ಲಿನ ಎಫ್-ಆಕ್ಟಿನ್ ಮಟ್ಟಕ್ಕೆ ಹೋಲಿಸಿದರೆ ಆಲ್ಝೈಮರ್ನ ರೋಗಿಗಳಲ್ಲಿ ಎಫ್-ಆಕ್ಟಿನ್ ಮಟ್ಟ ಕಡಿಮೆ ಎಂದು ಸಂಶೋಧಕರು ಗಮನಿಸಿದ್ದಾರೆ. ಈ ರೋಗದ ಪ್ರಕ್ರಿಯೆಯಲ್ಲಿ ಬಹಳ ಮುಂಚಿನ ಹಂತದಲ್ಲೇ ಎಫ್-ಆಕ್ಟಿನ್ಗೆ ಯಾವುದೇ ರೀತಿಯ ಹಾನಿ ಉಂಟಾದರೆ ಕಂಡುಕೊಳ್ಳಬಹುದು ಎಂದು ಅವರು ಪ್ರತಿಪಾದಿಸಿದ್ದಾರೆ.  "ಆಲ್ಝೈಮರ್ನ ಖಾಯಿಲೆಯಲ್ಲಿ, ಮೆದುಳಿನಲ್ಲಿ ಉಂಟಾಗುತ್ತಿರುವ ಅಸಹಜತೆಯ ಆರಂಭಿಕ ಸೂಚಕವಾಗಿ ಎಫ್-ಆಕ್ಟಿನ್ನ ವಿಭಜನೆಯನ್ನು ಮಾನದಂಡವಾಗಿ ಇರಿಸಿಕೊಳ್ಳಬಹುದು ಎಂದು ನಮ್ಮ ಅಧ್ಯಯನವು ತೋರಿಸಿಕೊಟ್ಟಿದೆ. ಹಾಗಾಗಿ, ಇದರ ಮೂಲಕ ಆಲ್ಝೈಮರ್ನ ಖಾಯಿಲೆಯನ್ನು ಮೊದಲ ಹಂತದಲ್ಲೇ ಗುರುತಿಸಬಹುದಾಗಿದೆ" ಎನ್ನುತ್ತಾರೆ ಡಾ. ವಿಜಯಲಕ್ಷ್ಮಿ.

ಹೀಗೆ ಮೊದಲ ಹಂತದಲ್ಲೇ ಗುರುತಿಸಲ್ಪಟ್ಟರೆ ಈ ಖಾಯಿಲೆಯ ಉಪದ್ರವವನ್ನುಕಡಿಮೆ ಮಾಡಬಹುದು. ಎಲ್ಲರಲ್ಲೂ ವಯಸ್ಸಾದಂತೆ ಮರೆವಿನ ಸಮಸ್ಯೆ ತಲೆದೋರಬಹುದು ಆದರೂ ನಮ್ಮ ಪ್ರೀತಿಪಾತ್ರರು ಕಡಿಮೆ ಪ್ರಾಯದಲ್ಲೇ ಸ್ಮರಣೆಯ ಸಮಸ್ಯೆ ಎದುರಿಸಿ ಹೈರಾಣಾಗುವುದನ್ನುಸಹಿಸಲು ಸಾಧ್ಯವಿಲ್ಲವಲ್ಲ? ಹಾಗಾಗಿ ಈ ಸಂಶೋಧನೆಯು ಖಂಡಿತ ಭರವಸೆದಾಯಕ.

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