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P. V. Sukumaran 《Resonance》1998,3(3):8-17
The bolide impact theory for mass extinctions at the Cretaceous-tertiary (K-T) boundary was a revolutionary concept. This
theory was contested by short duration global volcanism as a possible alternative cause for the K-T extinction. Though there
is a converging evidence for an extra-terrestrial impact coinciding with the terminal Cretaceous, the causative link between
the impact and the K-T mass extinction is debatable. Thus, while the impact theory is re-emerging, available evidence is still
insufficient to rule out either of the two hypotheses.
An erratum to this article is available at . 相似文献
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P V Sukumaran 《Resonance》2001,6(11):4-17
The prebiotic organic synthesis occurred in a reducing or mildly oxidising atmosphere. There was no dearth of energy sources
to drive this reaction. The speculation that life originated in ocean floor vent habitats is supported by the recent discovery
of fossil microbes in a mid-Archaean vent ecosystem. Evidence from nucleic acid sequencing that the last common ancestor of
all extant life is a hyperthermophile also lends credence to this hypothesis. The first living molecule that held heritable
genetic information was probably ribonucleicacid. The course of events that nature would have followed to reach the RNA-world
is fairly clear, but simulating this course in the laboratory to reach RNA remains a formidable problem and has little relevance
to an early Earth setting. A prolonged period of abiotic chemical evolution undoubtedly preceded the emergence of the first
living molecule.
P V Sukumaran took his M Tech degree in applied geology from the University of Saugar and has been with the Geological Survey
of India since 1974. His interests include petrology, geochemistry, palaeoceanography and organic evolution. He is presently
posted as Director in the Department at Nagpur 相似文献
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Sailajah Sukumaran Vanessa A. Green 《International Journal of Inclusive Education》2013,17(8):821-844
Inclusive education has been introduced through a number of policy developments in Malaysia over the last 10 years but there is little research investigating the extent and nature of inclusive education for preschoolers with special educational needs (SEN). This study surveyed both regular and special education teachers in Malaysian integrated preschools asking them about the level and nature of inclusion taking place in their preschools and their perceptions and beliefs about inclusion. There was little evidence of practices of inclusion taking place. Both regular and special educators agreed that SEN should be educated alongside their peers in a school but were unlikely to agree that the SEN students should be in the same classroom. Factors identified as influencing inclusion included school culture, skills and competency, guidance and information, workload and students' disabilities. More guidelines and support are required for successful inclusion in Malaysian integrated preschools. 相似文献
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P. V. Sukumaran 《Resonance》2001,6(10):16-28
The Earth accreted from planetesimals 4.6 Ga1 ago. The first few hundred million years were unfavourable for any kind of organic synthesis. Available evidences indicate
that the time window for the origin of life on Earth is between 4.1 and 3.8 Ga ago. This period coincides with the late heavy
bombardment of the inner Solar System by comets and asteroids and is too short for a complex system as life to have evolved
from prebiotic chemistry. It is, therefore, speculated that at least some of the precursor organic compounds were impact-delivered
to the early Earth by comets. These extraterrestrial bodies also supplied much of the Earth’s volatiles. 相似文献
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P. V. Sukumaran 《Resonance》2000,5(9):8-21
The proto-ocean owes its origin to condensation of water vapour from the proto-atmosphere. Much of this ocean was lost to subsequent giant impacts. The water of the modern ocean is largely secondary, delivered by cometary impacts soon after the Moon-forming event. The early ocean had low dissolved O2 and SO 4 2− but had high pH and dissolved Fe2+. 相似文献
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Lazaro Alessandro Soares Nunes Sayeeda Mussavira Omana Sukumaran Bindhu 《Biochemia medica : ?asopis Hrvatskoga dru?tva medicinskih biokemi?ara / HDMB》2015,25(2):177-192
This systematic review presents the latest trends in salivary research and its applications in health and disease. Among the large number of analytes present in saliva, many are affected by diverse physiological and pathological conditions. Further, the non-invasive, easy and cost-effective collection methods prompt an interest in evaluating its diagnostic or prognostic utility. Accumulating data over the past two decades indicates towards the possible utility of saliva to monitor overall health, diagnose and treat various oral or systemic disorders and drug monitoring. Advances in saliva based systems biology has also contributed towards identification of several biomarkers, development of diverse salivary diagnostic kits and other sensitive analytical techniques. However, its utilization should be carefully evaluated in relation to standardization of pre-analytical and analytical variables, such as collection and storage methods, analyte circadian variation, sample recovery, prevention of sample contamination and analytical procedures. In spite of all these challenges, there is an escalating evolution of knowledge with the use of this biological matrix.Key words: saliva, non-invasive, biological markers, drug monitoring, oral health 相似文献
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P. V. Sukumaran 《Resonance》2000,5(5):6-14
In Part 1 we described the early atmosphere which was rich in nitrogen and carbon dioxide and was oxygen deficient. In due
course photosynthesis liberated free O2 from CO2. The abundance of O2 reached modern levels by the turn of the Proterozoic
and triggered metazoan radiation. However tectonic activity exerted the ultimate control on the growth of atmospheric O2 by
enhanced organic carbon burial in sediments. 相似文献
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P. V. Sukumaran 《Resonance》1999,4(12):4-10
Molecular O2 and H2O are the vital requirements of contemporary life. The evolution of the atmosphere and oceans, therefore, necessarily predates
metazoan evolution on the earth. The prebiotic primary atmosphere had CH4, NH3 and H2 as the chief components and was O2-deficient. Dissociation of CH4 and NH3 paved the way for the secondary atmosphere composed principally of CO2. 相似文献
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