253 research outputs found

    A Ring with a Spin : Superfluidity in a toroidal Bose-Einstein condensate

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    Superfluidity is a remarkable phenomenon. Superfluidity was initially characterized by flow without friction, first seen in liquid helium in 1938, and has been studied extensively since. Superfluidity is believed to be related to, but not identical to Bose-Einstein condensation, a statistical mechanical phenomena predicted by Albert Einstein in 1924 based on the statistics of Satyendra Nath Bose, where bosonic atoms make a phase transition to form a Bose-Einstein condensate (BEC), a gas which has macroscopic occupation of a single quantum state. Developments in laser cooling of neutral atoms and the subsequent realization of Bose-Einstein condensates in ultracold gases have opened a new window into the study of superfluidity and its relation to Bose-Einstein condensation. In our atomic sodium BEC experiment, we studied superfluidity and dissipationless flow in an all-optical toroidal trap, constructed using the combination of a horizontal ``sheet''-like beam and vertical ``ring''-like beam, which, like a circuit loop, allows flow around the ring. On inducing a single quantum of circulation in the condensate, the smoothness and uniformity of the toroidal BEC enabled the sustaining of a persistent current lasting 40 seconds, limited by the lifetime of the BEC due to background gas pressure. This success set the stage for further experiments studying superfluidity. In a first set of experiments, we studied the stability of the persistent current by inserting a barrier in the flow path of the ring. The superflow stopped abruptly at a barrier strength such that the local flow velocity at the barrier exceeded a critical velocity, which supported decay via the creation of a vortex-antivortex pair. Our precise control in inducing and arresting superflow in the BEC is a first step toward studying other aspects of superfluidity, such as the effect of temperature and dimensionality. This thesis discusses these experiments and also details partial-transfer absorption imaging, an imaging technique developed in the course of this work

    Evidence of surface cooling from absorbing aerosols

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    Anthropogenic emissions over the Asian region have grown rapidly with increase in population and industrialization. Air-pollutants from this region lead to a brownish haze over most of the North Indian Ocean and South Asia during winter and spring. The haze, with as much as 10-15 of black carbon (by mass), is known to reduce the surface solar insolation by about 10 (-15 Wm -2) and nearly double the lower atmospheric solar heating. Here we present an analysis of observed surface-temperature variations over the Indian subcontinent, which filters out effects of greenhouse gases and natural variability. The analysis reveals that the absorbing aerosols have led to a statistically significant cooling of about 0.3°C since the 1970s. The seasonally asymmetric cooling, which is consistent with the seasonality of the South Asian aerosol forcing, raises the new possibility that the surface cooling underneath the polluted regions, is balanced by warming elsewhere

    Evidence of surface cooling from absorbing aerosols

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    Anthropogenic emissions over the Asian region have grown rapidly with increase in population and industrialization. Air-pollutants from this region lead to a brownish haze over most of the North Indian Ocean and South Asia during winter and spring. The haze, with as much as 10–15% of black carbon (by mass), is known to reduce the surface solar insolation by about 10% (−15 Wm−2) and nearly double the lower atmospheric solar heating. Here we present an analysis of observed surface-temperature variations over the Indian subcontinent, which filters out effects of greenhouse gases and natural variability. The analysis reveals that the absorbing aerosols have led to a statistically significant cooling of about 0.3°C since the 1970s. The seasonally asymmetric cooling, which is consistent with the seasonality of the South Asian aerosol forcing, raises the new possibility that the surface cooling underneath the polluted regions, is balanced by warming elsewhere

    Residue conservation and dimer-interface analysis of olfactory receptor molecular models

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    Olfactory Receptors (ORs) are members of the Class A rhodopsin like G-protein coupled receptors (GPCRs) which are the initial players in the signal transduction cascade, leading to the generation of nerve impulses transmitted to the brain and resulting in the detection of odorant molecules. Despite the accumulation of thousands of olfactory receptor sequences, no crystal structures of ORs are known tο date. However, the recent availability of crystallographic models of a few GPCRs allows us to generate homology models of ORs and analyze their amino acid patterns, as there is a huge diversity in OR sequences. In this study, we have generated three-dimensional models of 100 representative ORs from Homo sapiens, Mus musculus, Drosophila melanogaster, Caenorhabditis elegans and Sacharomyces cerevisiae which were selected on the basis of a composite classification scheme and phylogenetic analysis. The crystal structure of bovine rhodopsin was used as a template and it was found that the full-length models have more than 90% of their residues in allowed regions of the Ramachandran plot. The structures were further used for analysis of conserved residues in the transmembrane and extracellular loop regions in order to identify functionally important residues. Several ORs are known to be functional as dimers and hence dimer interfaces were predicted for OR models to analyse their oligomeric functional state

    EMR Adoption: A User Perception Study

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    Despite promise of significant benefits, inadequate user acceptance has frequently limited the impact of EMR implementations. Using an action research approach, our team is participating in an EMR implementation at Aravind Eye Care System (AECS), one of the largest eye hospitals in the world, to observe its current practices, measure user perceptions of EMR, plan interventions, and assess their impact. Our proximate research objective is to develop interventions based on sound conceptual foundations and empirical validation rather than in an ad hoc manner, to facilitate EMR acceptance by AECS hospital staff. The ensuing goal is to learn from the post intervention findings to develop guidelines for EMR implementations, particularly in a developing country context. In this paper we report on the first phase of this study, and these initial results show how even simple analysis of perception patterns can help to customize and shape intervention plans

    Identification of Benzoxazolinone Derivatives Based Inhibitors for Depression and Pain Related Disorders Using Human Serotonin and Norepinephrine Transporter as Dual Therapeutic Target: A Computational Approach

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    Pain is commonly associated with depression. Both pain and depression share common biological pathways and neurotransmitters, which has implications for the treatment of both disorders. A drug that could ameliorate both pain and depression could be beneficial in the development of new therapeutics in the management of disorders associated with pain/depression dyad. Alterations in the neurotransmitters namely, serotonin and norepinephrine in the central nervous system (CNS) have been implicated in the pathophysiology of pain and depression. Serotonin and norepinephrine reuptake inhibitors (SNRIs) have been implicated as a novel therapeutic target for a wide range of biological functions, including pain, anxiety and depression. 2-benzoxazolinone (2-BOA) from the mangrove Acanthus ilicifolius and its derivatives have been reported for its analgesic and antidepressant activities. In the present work, docking studies were done on the crystal structure of human transporters of serotonin (hSERT) and on homology modeled human transporters of norepinephrine (hNET) as therapeutic targets of depression and pain related disorders using 2-BOA and its derivatives as potential candidates. A homology model for hNET was constructed using MODELLER and validated. Further docking studies were done on hSERT and hNET using 2-BOA and its structural analogs. The result of the study proposes the possible potential candidate among 2-BOA derivatives that may be further developed as a therapeutic lead compound for use in disorders associated with depression and pain

    Productivity, performance and technical efficiency in banking: the foreign bank’s Saga in the context of financial reforms in India

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    This paper is an attempt to examine the total productivity growth of foreign banks for the period 2002-2003 to 2013-2014. Data of ten major foreign sector banks for twelve years were used for the analysis and interpretation. Malmquist Productivity Index and Input oriented CRS data envelopment analysis are being used to measure the productivity of these banks over the years. Along with the productivity of foreign sector banks, their performances were also determined through ratios. The results show that the foreign sector banks has obtained an excellent mean TFP of 1.06 and nine foreign sector banks has obtained an eligible score of one which depicts that foreign sector banks are doing well in the country. The excellent performance of foreign sector banks in the banking industry is further substantiated with the ratios. The study has revealed that by enlarging the scope of foreign banks will obviously bring growth, development and technological advancement in the Indian banking Sector. The Kelaniya Journal of Management, Vol. 4(1); 2015: 50-6

    Emergency revascularization in patients with cardiogenic shock on admission: a report from the SHOCK trial and registry

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    Aims To determine clinical correlates and optimal treatment strategy in patients with cardiogenic shock (CS) on admission. Methods and results In SHould we emergently revascularize Occluded Coronaries in cardiogenic shocK? (SHOCK) trial and registry patients with left ventricular (LV) dysfunction (n=1053), CS on admission occurred in 26% of directly admitted patients (n=166/627). Time from myocardial infarction to CS was shorter, initial haemodynamic profile poorer, and aggressive treatment less frequent in CS on admission than in delayed CS patients. CS on admission patients constituted a smaller relative proportion (11%) of the transferred (n=48/426) when compared with the directly admitted cohort (P<0.001). In-hospital mortality was higher (75 vs. 56%; P<0.001) with more rapid death (24-h mortality 40 vs. 17%; P<0.001) in CS on admission than in delayed CS patients. Emergency revascularization reduced in-hospital mortality in CS on admission (60 vs. 82%; P=0.001) and in delayed CS patients similarly (46 vs. 62%; P<0.001; interaction P=0.25). After adjustment for clinical differences, CS on admission was an independent predictor of in-hospital mortality (P=0.008). Conclusion CS on admission patients have a worse outcome but benefit equally from emergency revascularization as delayed CS patients, emphasizing the need for rapid and direct access of CS on admission patients to facilities providing this car
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