138 research outputs found

    Covariant formalism for the Berry connection due to gravity

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    It is well-known that Dirac particles gain geometric phase, namely Berry phase, while moving in an electromagnetic field. Researchers have already shown covariant formalism for the Berry connection due to an electromagnetic field. A similar effect is expected to happen due to the presence of Gravity. We use WKB approximation to develop a covariant formalism of Berry-like connection in the presence of Einstein gravity, which can be further used to describe the Berry-like phase or simply Berry phase. We also extend this formalism for massless Dirac particles (Weyl particles).Then we further show that this connection can be split into two parts, one of which vanishes when the metric is spherically symmetric and thus can be linked to the Aharonov-Bohm-like effect in the 3 + 1 formalism. At the same time, the other term can be related to the Pancharatnam-Berry like effect.Comment: 6 pages; published in Scientific Voyag

    Semiclassical analysis of Dirac fields on curved spacetime

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    We present a semiclassical analysis for Dirac fields on an arbitrary spacetime background and in the presence of a fixed electromagnetic field. Our approach is based on a Wentzel-Kramers-Brillouin approximation, and the results are analyzed at leading and next-to-leading order in the small expansion parameter \hbar. Taking into account the spin-orbit coupling between the internal and external degrees of freedom of wave packets, we derive effective ray equations with spin-dependent terms. These equations describe the gravitational spin Hall effect of localized Dirac wave packets. We treat both massive and massless Dirac fields and show how a covariantly defined Berry connection and the associated Berry curvature govern the semiclassical dynamics. The gravitational spin Hall equations are shown to be particular cases of the Mathisson-Papapetrou equations for spinning objects

    STUDY OF EARLY AND LATE ONSET COMPLICATIONS OF TRANSSPHENOIDAL PITUITARY ADENOMA RESECTION: AN INSTITUITIONAL EXPERIENCE.

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    Introduction:Considering the unique anatomical location and important role of pituitary gland in regulation of various endocrine functions, various postoperative complications are expected resulting from surgery on pituitary tumor. In this study, we analyzed various complications of transsphenoidal pituitary surgery and factors affecting it. Material and method:Study was conducted between September 2015 to November 2016 on a total of 60 patients. All clinical and surgical data were collected regarding tumor size, symptoms, and residual tumor after surgery, functional remission, symptom relief, and complications. All patients underwent neurological, ophthalmological, and endocrinological examinations before and after resection. Result:Out of 60 patients 43 were operated endoscopically and 17 were operated microscopically. Perioperatively, arachnoid tear was present in 20(33.33%) patients. 23(38.34%) cases were having total resection post-operatively, 20(33.33%) cases were having subtotal resection and in 17 (28.33%) cases either partial resection done or biopsy was taken. Grade of tumor resection was significantly associated with preoperative extent of tumor (p-value-0.003). CSF -leak was associated with Perioperative arachnoid tear significantly (p- value <0.001). Conclusion:Some complications are there in immediate post operative period, but on follow up, both endoscopic and microscopic procedures have fewer side effects and there was no statistical significant difference in complication rate in both types of surgery

    The study of serum c-reactive protein and its diagnostic importance in reducing the rate of negative appendectomy

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    Background: Introduction-Acute appendicitis is the most common abdominal surgical emergency and appendectomy is one of the most frequently performed abdominal operation but the diagnosis of acute appendicitis remains an enigmatic challenge, plagued by high rate of negative exploration. The objective of this study was to assess the accuracy of CRP over TLC in the diagnosis of acute appendicitis.Methods: Total 200 patients who had been diagnosed as a case of acute appendicitis based on WBC count and clinical diagnosis and were planned for appendectomy were selected for purposive sampling. Serum CRP was estimated in these patients before operation but was not considered in decision making process of appendectomy. All 200 removed appendixes were sent for histopathological examination.Results: Result-Sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of serum CRP were much greater than WBC count. Mean and standard deviation of serum CRP was 41.92±26.28 with p=<0.0001 which is highly significant.Conclusions: Conclusion-CRP should be added along with clinical diagnosis and other laboratory test in diagnosis of acute appendicitis to reduce the rate of negative appendectomy

    3D QSAR analysis on quinoxaline derivatives as anti-malarial using K-nearest neighbour molecular field analysis 

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    In the present article, k nearest neighbour molecular field analysis (kNN-MFA) method was used to develop a three dimensional quantitative structure activity relationship (3D-QSAR) model. In this study 37 derivatives of quinoxaline having antimalarial activity were used. Sphere exclusion (SE) algorithm was used to create the biological activity data set in to into training and test set. For model generation kNN-MFA method has coupled with stepwise, simulated annealing and genetic algorithm this method provides various models, in which the most significant model developed by stepwise backward-forward method with predictive internal q2=0.7589 and external predictivity (pred_r2 = 0.4752). In the presented model electrostatic descriptors play crucial role for activity. Electrostatic descriptor (E_137) indicates regions in which electron withdrawing groups are favourable and descriptor (E_939) represents electron rich or electron donating groups are advantageous in particular region. The counter map/ plot of this model further helps to understand the relationship of structural feature of derivative of quinoxaline and its biological activity this would be applied for designing of new potent antimalarial containing quinoxaline as lead.

    3D QSAR analysis on quinoxaline derivatives as anti-malarial using K-nearest neighbour molecular field analysis

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    727-731In the present article, k nearest neighbour molecular field analysis (kNN-MFA) method was used to develop a three dimensional quantitative structure activity relationship (3D-QSAR) model. In this study 37 derivatives of quinoxaline having antimalarial activity were used. Sphere exclusion (SE) algorithm was used to create the biological activity data set in to into training and test set. For model generation kNN-MFA method has coupled with stepwise, simulated annealing and genetic algorithm this method provides various models, in which the most significant model developed by stepwise backward-forward method with predictive internal q2=0.7589 and external predictivity (pred_r2 = 0.4752). In the presented model electrostatic descriptors play crucial role for activity. Electrostatic descriptor (E_137) indicates regions in which electron withdrawing groups are favourable and descriptor (E_939) represents electron rich or electron donating groups are advantageous in particular region. The counter map/ plot of this model further helps to understand the relationship of structural feature of derivative of quinoxaline and its biological activity this would be applied for designing of new potent antimalarial containing quinoxaline as lead

    Lumbosacral myelocystocele: A case report

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    Myelocystocele is a rare variety of spinal dysraphism that presents as a skin covered, midline, lumbosacral mass. Many a time it is associated with other congenital anomalies but isolated myelocystocele is rarely associated with neurological deficit. MRI is the modality of choice for preoperative diagnosis. A 3 years old female child presented with skin covered lumbosacral mass since birth. There was no associated neurological deficit. MRI revealed single cyst, which was continuous with central canal of spinal cord. Peroperatively, myelocystocele was found with tethering of cord. Untethering of cord and repair of myelocystocele was performed with uneventful recovery

    Challenges in setting up a large population-based prospective cohort study in India – learnings from the LoCARPoN cohort

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    Population-based prospective cohort studies can yield vital new evidence. However, they are difficult to setup especially in non-western contexts such as India. We describe our experience in establishing the Longitudinal Cognition and Aging Research on Population of the National Capital Region (LoCARPoN) cohort, which was the first-of-its-kind public-funded study with target sample size of 15,000, 3 sites, and funds of approx. US$ five million for eight years (2014–2022). LoCARPoN aimed to study incident stroke and dementia in adults aged ≥50 years in urban and rural populations of north India. Among the numerous challenges encountered, important were inadequate funding, lack of adequate space for medical and field sites, difficulty in hiring manpower, lack of IT infrastructure, non-availability of storage facility for biological samples, and absence of dedicated MRI machines. Meticulous planning, adequate funding, trained personnel, institutional and community support are critical for establishing such cohorts in the non-western contexts. Funding: The LoCARPoN cohort study was funded by the Department of Biotechnology (Grant No. BT/IN/Netherlands/03/KP/2012 dated 14/02/2014); and Department of Health Research (Grant No. R.11012/15/2018-HR, dated 09/08/2018), Government of India. The Erasmus component was funded through the Erasmus Medical Centre, Rotterdam, The Netherlands, and the Erasmus University, Rotterdam ( Alzheimer Nederland WE.15-2014-09).</p

    Mobilization of Stem Cells Using G-CSF for Acute Ischemic Stroke: A Randomized Controlled, Pilot Study

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    Background. There is emerging evidence to support the use of granulocyte colony-stimulating factor (G-CSF) therapy in patients with acute ischemic stroke. Aims. To explore feasibility, safety, and preliminary efficacy of G-CSF therapy in patients with acute ischemic stroke. Patients and Method. In randomized study, 10 patients with acute ischemic stroke were recruited in 1 : 1 ratio to receive 10 μg/kg G-CSF treatment subcutaneously daily for five days with conventional care or conventional treatment alone. Efficacy outcome measures were assessed at baseline, one month, and after six months of treatment included Barthel Index (BI), National Institute of Health Stroke Scale, and modified Rankin Scale. Results. One patient in G-CSF therapy arm died due to raised intracranial pressure. No severe adverse effects were seen in rest of patients receiving G-CSF therapy arm or control arm. No statistically significant difference between intervention and control was observed in any of the scores though a trend of higher improvement of BI score is seen in the intervention group. Conclusion. Although this study did not have power to examine efficacy, it provides preliminary evidence of potential safety, feasibility, and tolerability of G-CSF therapy. Further studies need to be done on a large sample to confirm the results
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