197 research outputs found

    N Fermion Ground State of Calogero-Sutherland Type Models in Two and Higher Dimensions

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    I obtain the exact ground state of NN-fermions in DD-dimensions (D2)(D \geq 2) in case the NN particles are interacting via long-ranged two-body and three-body interactions and further they are also interacting via the harmonic oscillator potential. I also obtain the NN-fermion ground state in case the oscillator potential is replaced by an NN-body Coulomb-like interaction.Comment: 10 pages, Latex fil

    A Class of Exact Solutions For N-Anyons in a N-body Potential

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    A class of exact solutions are obtained for the problem of N-anyons interacting via the N-body potential V(x1,x2,...,xN)V (\vec x_1,\vec x_2,...,\vec x_N) = e21Ni<j(xixj)2-{e^2\over\sqrt{{1\over N}\sum_{i<j} (\vec x_i-\vec x_j)^2}} Unlike the oscillator case the resulting spectrum is not linear in the anyon parameter α(0α1)\alpha (0\leq \alpha\leq 1). However, a la oscillator case, cross-over between the ground states is shown to occur for N-anyons (N3)(N\geq 3) experiencing the above potential.Comment: 10 pages, no figure, latex fil

    Prediction of rock load emphasizing excavation damage of in situ rockscaused by blasting in coal mines

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    Roof failure in coal mines is strongly related to the frequency of laminations and their movement when the load acts upon them. Detachment of roof bolts from mine roof due to improper estimation of extent of weak zone is one of the major problems in underground coal mines, thus affecting the safety and productivity of workings. The most popular and practiced method for roof support design in Indian coal mines is the Central Mining Research Institute-ISM geomechanical classification system. Irrespective of such an established system of support design, accidents due to roof fall still persist. Here we review various available classification systems for rock load estimation and identify their limitations. The study has been extended taking into consideration the case study of KTK-6 incline of Singareni Collieries Company Limited by proposing a modified rock mass classification system based on seismic wave velocity as a key descriptor. A modified rock mass rating (RMR) system (RMRdyn) with inclusion of seismic velocity as one of the parameters is proposed for the estimation of rock load. Enhancement in rock load by 20% has been found for RMRCMRI-ISM values less than 40 according to the new rock load relation. This resulted in under-supporting of the roof and thus might have caused failures. For cases with RMRCMRI-ISM values more than 60, the earlier equation overestimates rock load by about 25% resulting in over-supporting. Thus, estimation of rock load from the proposed new equation appears to be more rational as it takes into account the actual damage zone

    Volar plating of isolated ulna shaft fractures

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    Background: Dorsal plating for ulna shaft fracture is a common practice. But this is associated with hardware prominence on the dorsal subcutaneous border of ulna necessitating implant removal on later days. Volar surface of ulna is flat similar to radius volar surface with good muscle cover reducing the problem of hardware prominence. So, we wanted to study the outcome of volar plating of ulnar shaft fractures.  Methods: Ten patients satisfying our inclusion criteria underwent volar plating using volar approach between FCU and ECU and 3.5 DCP was placed on flat volar surface of ulnar shaft under thick muscle cover of FCU and FDP. Results: Out of 10 patients, 7 were acute fractures, 2 were neglected non unions and 1was non-union with implant insitu. Bone graft was used in non-union cases. All fractures united at 6-9 month post op without any complications. Conclusions: Isolated ulnar shaft fractures are common orthopaedic injuries. Displaced fractures require stabilization with dynamic compression plate (DCP). Application of implant on its volar aspect in distal 2/3rd fractures is easy due to flat surface and avoids complications related to hard ware prominence and subsequent need for implant removal

    Cardiac Lipoma: An Uncharacteristically Large Intra-Atrial Mass Causing Symptoms

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    Primary tumours of the heart are often encountered in clinical practice. Different autopsy series estimate the incidence to be anywhere from 0.001% to 0.19%. Cardiac lipoma is a rare type of tumour of the heart and pericardium. It comprises approximately 10–19% of all cardiac tumours. We present a case of a large cardiac lipoma in a fifty-year-old female. She presented with sharp chest pains, palpitations, and dizziness. Acute coronary syndrome was ruled out. A transthoracic echocardiogram showed an abnormal, large, fixed right atrial mass. The mass was noted to be occupying most of the right atrium. It was excised due to its large size and persistent symptoms. On pathophysiology, the mass was definitively diagnosed to be an 80 mm × 70 mm cardiac lipoma. Postoperatively, the patient did well with resolution of her symptoms. This case provides evidence that even large, invasive, symptomatic cardiac lipomas can be successfully resected with good outcomes

    Structural deformation and displacement of a disc winding due to standard switching impulse voltage via finite element method

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    Switching operations in a power system network can lead to transient overvoltage in the high voltage (HV) winding of distribution transformers that causes high-stress build-up. This paper presents the relationship between electromagnetic force due to a standard switching impulse (SSI) and mechanical deformation/displacement behaviours for a disc-type transformer. The analysis was carried out based on a three-dimensional (3D) modelling of a continuous HV disc winding configuration whereby it is subjected to the switching transient voltage and force excitations through the finite element method (FEM). The electric transient solver analysed the static and dynamic aspects of the electromagnetic forces associated with the variation of forces versus time. The transient structural solver evaluated the structural behaviours of the disc winding related to the axial height and radial width of the winding under electromagnetic forces. It is found that the positively dominant axial force generated in the winding with a magnitude of 8.7 N causes the top and bottom layers of disc winding to tilt and displace. In addition, the positive average radial force of 1.4 N causes the circumference of the winding to experience hoop tension and outwardly stretch. © Universiti Putra Malaysia Press

    Investigation on the resonant oscillations in an 11kV distribution transformer under standard and chopped lightning impulse overvoltages with different configurations of shield placements

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    This paper presents an investigation on the resonant oscillations of an 11 kV layer-type winding transformer under standard and chopped lightning impulse overvoltage conditions based on calculated parameters. The resistances, inductances and capacitances were calculated in order to develop the transformer winding equivalent circuit. The impulse overvoltages were applied to the high voltage (HV) winding and the resonant oscillations were simulated for each of the layers based on different electrostatic shield placement configurations. It is found that the placement of grounded shields between layer 13 and layer 14 results in the highest resonant oscillation and non-linear initial voltage distribution. The oscillation and linear stress distributions are at the lowest for shield placement between the HV and low voltage (LV) windings

    Investigation on the transient voltage in a 11 kV transformer under lightning surges

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    This paper investigates the transient voltage distribution in a 11 kV layer type winding transformer under a standard 1.2/50 µs lightning impulse. The winding parameters known as resistance (R), inductance (L) and capacitance (C) were obtained through numerical calculation which were used to simulate the lumped equivalent circuit model. The calculated and simulated voltage distributions in all the layers of HV winding were analyzed. There is a steep and linear distribution of simulated and calculated voltage

    Semaglutide and cardiovascular outcomes in patients with obesity and prevalent heart failure: a prespecified analysis of the SELECT trial

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    Background: Semaglutide, a GLP-1 receptor agonist, reduces the risk of major adverse cardiovascular events (MACE) in people with overweight or obesity, but the effects of this drug on outcomes in patients with atherosclerotic cardiovascular disease and heart failure are unknown. We report a prespecified analysis of the effect of once-weekly subcutaneous semaglutide 2·4 mg on ischaemic and heart failure cardiovascular outcomes. We aimed to investigate if semaglutide was beneficial in patients with atherosclerotic cardiovascular disease with a history of heart failure compared with placebo; if there was a difference in outcome in patients designated as having heart failure with preserved ejection fraction compared with heart failure with reduced ejection fraction; and if the efficacy and safety of semaglutide in patients with heart failure was related to baseline characteristics or subtype of heart failure. Methods: The SELECT trial was a randomised, double-blind, multicentre, placebo-controlled, event-driven phase 3 trial in 41 countries. Adults aged 45 years and older, with a BMI of 27 kg/m2 or greater and established cardiovascular disease were eligible for the study. Patients were randomly assigned (1:1) with a block size of four using an interactive web response system in a double-blind manner to escalating doses of once-weekly subcutaneous semaglutide over 16 weeks to a target dose of 2·4 mg, or placebo. In a prespecified analysis, we examined the effect of semaglutide compared with placebo in patients with and without a history of heart failure at enrolment, subclassified as heart failure with preserved ejection fraction, heart failure with reduced ejection fraction, or unclassified heart failure. Endpoints comprised MACE (a composite of non-fatal myocardial infarction, non-fatal stroke, and cardiovascular death); a composite heart failure outcome (cardiovascular death or hospitalisation or urgent hospital visit for heart failure); cardiovascular death; and all-cause death. The study is registered with ClinicalTrials.gov, NCT03574597. Findings: Between Oct 31, 2018, and March 31, 2021, 17 604 patients with a mean age of 61·6 years (SD 8·9) and a mean BMI of 33·4 kg/m2 (5·0) were randomly assigned to receive semaglutide (8803 [50·0%] patients) or placebo (8801 [50·0%] patients). 4286 (24·3%) of 17 604 patients had a history of investigator-defined heart failure at enrolment: 2273 (53·0%) of 4286 patients had heart failure with preserved ejection fraction, 1347 (31·4%) had heart failure with reduced ejection fraction, and 666 (15·5%) had unclassified heart failure. Baseline characteristics were similar between patients with and without heart failure. Patients with heart failure had a higher incidence of clinical events. Semaglutide improved all outcome measures in patients with heart failure at random assignment compared with those without heart failure (hazard ratio [HR] 0·72, 95% CI 0·60-0·87 for MACE; 0·79, 0·64-0·98 for the heart failure composite endpoint; 0·76, 0·59-0·97 for cardiovascular death; and 0·81, 0·66-1·00 for all-cause death; all pinteraction&gt;0·19). Treatment with semaglutide resulted in improved outcomes in both the heart failure with reduced ejection fraction (HR 0·65, 95% CI 0·49-0·87 for MACE; 0·79, 0·58-1·08 for the composite heart failure endpoint) and heart failure with preserved ejection fraction groups (0·69, 0·51-0·91 for MACE; 0·75, 0·52-1·07 for the composite heart failure endpoint), although patients with heart failure with reduced ejection fraction had higher absolute event rates than those with heart failure with preserved ejection fraction. For MACE and the heart failure composite, there were no significant differences in benefits across baseline age, sex, BMI, New York Heart Association status, and diuretic use. Serious adverse events were less frequent with semaglutide versus placebo, regardless of heart failure subtype. Interpretation: In patients with atherosclerotic cardiovascular diease and overweight or obesity, treatment with semaglutide 2·4 mg reduced MACE and composite heart failure endpoints compared with placebo in those with and without clinical heart failure, regardless of heart failure subtype. Our findings could facilitate prescribing and result in improved clinical outcomes for this patient group. Funding: Novo Nordisk

    Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

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    IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570
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