488 research outputs found

    One Parameter Solution of Spherically Symmetric Accretion in Various Pseudo-Schwarzschild Potentials

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    In this paper we have solved the hydrodynamic equations governing the spherically symmetric isothermal accretion (wind) onto (away from) compact objects using various pseudo-Schwarzschild potentials.These solutions are essentially one parameter solutions in a sense that all relevant dynamical as well as thermodynamic quantities for such a flow could be obtained (with the assumption of a one-temperature fluid) if {\it only one} flow parameter (temperature of the flow TT) is given. Also we have investigated the transonic behaviour of such a flow and showed that for a given TT, transitions from subsonic to the supersonic branch of accretion (wind) takes place at different locations depending on the potentials used to study the flow and we have identified these transition zones for flows in various such potentials.Comment: 9 pages, 3 black and white post-script figures. Published in the International Journal of Modern Physics D (IJMPD

    tagE: Enabling an Embodied Agent to Understand Human Instructions

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    Natural language serves as the primary mode of communication when an intelligent agent with a physical presence engages with human beings. While a plethora of research focuses on natural language understanding (NLU), encompassing endeavors such as sentiment analysis, intent prediction, question answering, and summarization, the scope of NLU directed at situations necessitating tangible actions by an embodied agent remains limited. The inherent ambiguity and incompleteness inherent in natural language present challenges for intelligent agents striving to decipher human intention. To tackle this predicament head-on, we introduce a novel system known as task and argument grounding for Embodied agents (tagE). At its core, our system employs an inventive neural network model designed to extract a series of tasks from complex task instructions expressed in natural language. Our proposed model adopts an encoder-decoder framework enriched with nested decoding to effectively extract tasks and their corresponding arguments from these intricate instructions. These extracted tasks are then mapped (or grounded) to the robot's established collection of skills, while the arguments find grounding in objects present within the environment. To facilitate the training and evaluation of our system, we have curated a dataset featuring complex instructions. The results of our experiments underscore the prowess of our approach, as it outperforms robust baseline models.Comment: Accepted in EMNLP Findings 202

    Sulfhydryls of tubulin

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    The 20 cysteine residues of tubulin are heterogeneously distributed throughout its three-dimensional structure. In the present work, we have used the reactivity of these cysteine residues with 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) as a probe to detect the global conformational changes of tubulin under different experimental conditions. The 20 sulfhydryl groups can be classified into two categories: fast and slow reacting. Colchicine binding causes a dramatic decrease in the reactivity of the cysteine residues and causes complete protection of 1.4 cysteine residues. Similarly, other colchicine analogs that bind reversibly initially decrease the rate of reaction; but unlike colchicine they do not cause complete protection of any sulfhydryl groups. Interestingly, in all cases we find that all the slow reacting sulfhydryl groups are affected to the same extent, that is, have a single rate constant. Glycerol has a major inhibitory effect on all these slow reacting sulfhydryls, suggesting that the reaction of slow reacting cysteines takes place from an open state at equilibrium with the native. Ageing of tubulin at 37 ° C leads to loss of self-assembly and colchicine binding activity. Using DTNB kinetics, we have shown that ageing leads to complete protection of some of the sulfhydryl groups and increased reaction rate for other slow reacting sulfhydryl groups. Ageing at 37 ° C also causes aggregation of tubulin as indicated by HPLC analysis. The protection of some sulfhydryl groups may be a consequence of aggregation, whereas the increased rate of reaction of other slow reacting sulfhydryls may be a result of changes in global dynamics. CD spectra and acrylamide quenching support such a notion. Binding of 8-anilino-1-naphthalenesulfonate (ANS) and bis-ANS by tubulin cause complete protection of some cysteine residues as indicated by the DTNB reaction, but has little effect on the other slow reacting cysteines, suggesting local effects

    Chaperone-like activity of tubulin. Binding and reactivation of unfolded substrate enzymes

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    The eukaryotic cytoskeletal protein tubulin is a heterodimer of two subunits, α and β , and is a building block unit of microtubules. In a previous communication we demonstrated that tubulin possesses chaperonelike activities by preventing the stress-induced aggregation of various proteins (Guha, S., Manna, T. K., Das, K. P., and Bhattacharyya, B. (1998) J. Biol. Chem. 273, 30077-30080). As an extension of this observation, we explored whether tubulin, like other known chaperones, also protected biological activity of proteins against thermal stress or increased the yields of active proteins during refolding from a denatured state. We show here that tubulin not only prevents the thermal aggregation of alcohol dehydrogenase and malic dehydrogenase but also protects them from loss of activity. We also show that tubulin prevents the aggregation of substrates during their refolding from a denatured state and forms a stable complex with denatured substrate. The activity of malic dehydrogenase, α -glucosidase, and lactate dehydrogenase during their refolding from urea or guanidium hydrochloride denatured states increased significantly in presence of tubulin compared with that without tubulin. These results suggest that tubulin, in addition to its role in mitosis, cell motility, and other cellular events, might be implicated in protein folding and protection from stress

    COLLOID VERSUS CRYSTALLOID COLOAD FOR THE PREVENTION OF SPINAL ANEASTHESIA INDUCED HYPOTENSION OF ELECTIVE CAESAREAN SECTION

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    Background Spinal anaesthesia is the standard technique for elective caesarean section, but hypotension remains the main complication with this technique. This hypotension has detrimental effects on both mother and foetus. To prevent hypotension, crystalloid or colloid coload with vesopressor may be an alternate choice. Aim To compare the efficacy of crystalloid and colloid coload in presence of phenylephrine infusion for the prevention of spinal anaesthesia induced hypotension. Methods Forty subjects (40) are randomly allocated into two groups. Subjects were infused either crystalloid or colloid within 10 minutes after spinal anaesthesia (coload).Heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean blood pressure (MBP) and oxygen saturation were recorded in three minutes interval throughout the surgery. Continuous ECG monitoring was done. Adverse events (nausea, vomiting etc) if any were recorded in case report form (CRF).  Phenylephrine infusion was continued at the rate of 40 mcg/min throughout the surgery. Results Demographic parameters were comparable. HR, SBP, DBP, MBP, Oxygen saturation all are comparable between the groups and within the group in various time period. There was no episode of nausea or vomiting and no requirement of rescue medication of phenylephrine 100 mcg intravenously. Conclusion There is no difference of efficacy of crystalloid and colloid, when use as coload with phenylephrine infusion for the prevention of spinal anaesthesia induced hypotension.   Key words –spinal anaesthesia, crystalloid, colloid, hypotensio

    Ellagic acid derivatives from the leaves of Eugenia jambos Linn

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    1316-131

    Pseudo-Schwarzschild description of transonic spherical accretion onto compact objects

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    A number of `modified' Newtonian potentials of various forms are available in the literature which accurately approximate some general relativistic effects important for studying accretion discs around a Schwarzschild black hole. Such potentials may be called `pseudo-Schwarzschild' potentials because they nicely mimic the space-time around a non-rotating/slowly rotating compact object. In this paper, we examine the validity of the application of some of these potentials to study the spherically symmetric, transonic, hydrodynamic accretion onto a Schwarzschild black hole. By comparing the values of various dynamical and thermodynamic accretion parameters obtained for flows using these potentials with full general relativistic calculations, we have shown that though the potentials discussed in this paper were originally proposed to mimic the relativistic effects manifested in disc accretion, it is quite reasonable to use most of the potentials in studying various dynamical as well as thermodynamic quantities for spherical accretion to compromise between the ease of handling of a Newtonian description of gravity and the realistic situations described by complicated general relativistic calculations. Also we have shown that depending on the chosen regions of parameter space spanned by specific energy E{\cal E} and adiabatic index Îł\gamma of the flow, one potential may have more importance than another and we could identify which potential is the best approximation for full general relativistic flow in Scwarzschild space-time for particular values of E{\cal E} and Îł\gamma.Comment: 15 one-column pages. 6 black and white post-script figures. Published in A&

    Study of relationship between age and body mass index on knee osteoarthritis in advanced aged females in a divisional city of Bangladesh

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    Background: Knee osteoarthritis is a notable issue in senior citizens and is a burning problem worldwide. There are so many risk factors related to knee osteoarthritis but women's sex, age, and obesity are significant. The aim and objective of this study were to estimate the prevalence of knee osteoarthritis among women in the age group of 46 to 65 years and the effect of age and body mass index (BMI) on knee osteoarthritis.Methods: Cross-sectional study was conducted at outpatient department (OPD) in Mymensingh Medical College Hospital, a tertiary level hospital, among females of Mymensingh, a divisional city of Bangladesh in the age group of 46 to 65 years. Purposive sampling technique used to select study subjects. A total of 100 females participated in this study in one month (July 2019-August 2019).Results: 100 participants were enlisted in the study, in the age group of 46 to 55 years 39 (39%) and 56 to 65 years 61 (61%). Total 65 (65%) participants were affected with knee osteoarthritis. Among them, 19 (29.2%) participants were in the age group of 46-55 years and 46 (70.8%) participants were in the age group of 55-65 years, thus in the advanced age group, knee osteoarthritis is remarkably more. Participants affected with knee osteoarthritis with BMI ≥25 were significantly more affected 45 (69.2%) compared with participants with normal BMI 20 (30.2%).Conclusions: Knee osteoarthritis is significantly associated with advanced age and obesity. Advanced age and overweight were strongly associated with osteoarthritis in our population. Therefore, weight reduction and preventive measures can decrease the burden and will help in minimizing morbidity associated with OA
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