End wall flows in rotors and stators of a single stage compressor

A computer code for solving the parabolized Navier-Stokes equations for internal flows was developed. Oscillations that develop in the calculation procedure are discussed. The measurements made in the hub and annulus wall boundary layers are summarized. The flow in the hub wall boundary layer, starting ahead of the inlet guide vanes to the inlet of the rotor is traced

Re-equilibration after quenches in athermal martensites:Conversion-delays for vapour to liquid domain-wall phases

Entropy barriers and ageing states appear in martensitic structural-transition models, slowly re-equilibrating after temperature quenches, under Monte Carlo dynamics. Concepts from protein folding and ageing harmonic oscillators turn out to be useful in understanding these nonequilibrium evolutions. We show how the athermal, non-activated delay time for seeded parent-phase austenite to convert to product-phase martensite, arises from an identified entropy barrier in Fourier space. In an ageing state of low Monte Carlo acceptances, the strain structure factor makes constant-energy searches for rare pathways, to enter a Brillouin zone `golf hole' enclosing negative energy states, and to suddenly release entropically trapped stresses. In this context, a stress-dependent effective temperature can be defined, that re-equilibrates to the quenched bath temperature.Comment: 11 pages, 12 figures. Under process with Phys. Rev. B (2015

Comparative Assessment on Linearity Test based V2π and Vπ/2 Voltage Variations of Closed Loop IFOG

Interferometric Fiber Optic Gyroscope (IFOG) has to operate in closed loop condition to achieve inertial grade performance. The closed loop system is mainly depends upon the amplitude of the ramp signal (V2π of IOC) and bias (square wave) signal frequency (fbias). The digital phase ramp function is given as feedback to the optical system and makes gyro to null condition. The peak-to-peak amplitude (Vπ/2) of biasing signal is one-fourth of the ramp amplitude (V2π). If there are any variations in the amplitude of the ramp and biasing signals, then it introduces variations in the gyro performance. In this paper, a comparative discussion made in the gyro parameters for three cases: (i) V2π (vary) & Vπ/2 (constant), (ii) Vπ/2 (vary) & V2π (constant) and (iii) both V2π and Vπ/2 are varying simultaneously. The effects on gyroscope are described with the derived values in terms of linearity. From the experimental results, it was observed that the gyro output is very sensitive with respect to V2π variations and obtained the percentage error of 10% in gyro output, but very less effect due to Vπ/2 variations. So, the proper resetting of ramp voltage (V2π) is required to avoid nonlinearities and instabilities in gyro output

Fermions at unitarity and Haldane Exclusion Statistics

We consider a gas of neutral fermionic atoms at ultra-low temperatures, with the attractive interaction tuned to Feshbach resonance. We calculate, the variation of the chemical potential and the energy per particle as a function of temperature by assuming the system to be an ideal gas obeying the Haldane-Wu fractional exclusion statistics. Our results for the untrapped gas compare favourably with the recently published Monte Carlo calculations of two groups. For a harmonically trapped gas, the results agree with experiment, and also with other published work.Comment: 4 pages, 1 postscript figur

D-branes in Unoriented Non-critical Strings and Duality in SO(N) and Sp(N) Gauge Theories

We exhibit exact conformal field theory descriptions of SO(N) and Sp(N) pairs of Seiberg-dual gauge theories within string theory. The N=1 gauge theories with flavour are realized as low energy limits of the worldvolume theories on D-branes in unoriented non-critical superstring backgrounds. These unoriented backgrounds are obtained by constructing exact crosscap states in the SL(2,R)/U(1) coset conformal field theory using the modular bootstrap method. Seiberg duality is understood by studying the behaviour of the boundary and crosscap states under monodromy in the closed string parameter space.Comment: 23 pages, 2 figure

Leprosy and tuberculosis concomitant infection: a poorly understood, age-old relationship

Historically, archaeological evidence, post-mortem findings and retro- spective analysis of leprosy institutions’ data demonstrates a high observed incidence of concomitant infection with leprosy and tuberculosis (TB). However, reports of concomitant infection in the modern literature remain scarce, with estimates of annual new case detection rates of concomitant infection at approximately 0·02 cases per 100,000 population. Whilst the mechanism for this apparent decline in concomitant infections remains unclear, further research on this topic has remained relatively neglected. Modelling of the interaction of the two organisms has suggested that the apparent decline in observations of concomitant infection may be due to the protective effects of cross immunity, whilst more recently others have questioned whether it is a more harmful relationship, predisposing towards increased host mortality. We review recent evidence, comparing it to previously held understanding on the epidemiological relationship and our own experience of concomitant infection. From this discussion, we highlight several under-investigated areas, which may lead to improvements in the future delivery of leprosy management and services, as well as enhance understanding in other fields of infection management. These include, a) highlighting the need for greater understanding of host immunogenetics involved in concomitant infection, b) whether prolonged courses of high dose steroids pre-dispose to TB infection? and, c) whether there is a risk of rifampicin resistance developing in leprosy patients treated in the face of undiagnosed TB and other infections? Longitudinal work is still required to characterise these temporal relationships further and add to the current paucity of literature on this subject matter

Electric Dipolar Susceptibility of the Anderson-Holstein Model

The temperature dependence of electric dipolar susceptibility \chi_P is discussed on the basis of the Anderson-Holstein model with the use of a numerical renormalization group (NRG) technique. Note that P is related with phonon Green's function D. In order to obtain correct temperature dependence of P at low temperatures, we propose a method to evaluate P through the Dyson equation from charge susceptibility \chi_c calculated by the NRG, in contrast to the direct NRG calculation of D. We find that the irreducible charge susceptibility estimated from \chi_c agree with the perturbation calculation, suggesting that our method works well.Comment: 4 pages, 4 figure

Analytical results for random walks in the presence of disorder and traps

In this paper, we study the dynamics of a random walker diffusing on a disordered one-dimensional lattice with random trappings. The distribution of escape probabilities is computed exactly for any strength of the disorder. These probabilities do not display any multifractal properties contrary to previous numerical claims. The explanation for this apparent multifractal behavior is given, and our conclusion are supported by numerical calculations. These exact results are exploited to compute the large time asymptotics of the survival probability (or the density) which is found to decay as $\exp [-Ct^{1/3}\log^{2/3}(t)]$. An exact lower bound for the density is found to decay in a similar way.Comment: 21 pages including 3 PS figures. Submitted to Phys. Rev.

Predisposing factors and clinical profile of acute severe asthma

Background: Asthma is a chronic inflammatory condition of the lung airways resulting in episodic airflow obstruction. It is also one of the leading causes of morbidity in children and hospital admissions. Current treatments, although helpful, are still unable to prevent childhood asthma exacerbations completely. Objectives: To study the clinical profile and predisposing factors for acute severe asthma in children. Methods: This prospective study was conducted between January 2015 and December 2015 in a tertiary care teaching hospital. Children between the age group of 5 and 18 years admitted with symptoms and signs of acute severe asthma formed the study group. Detailed history and examination were recorded in a systematically designed pro forma, and these patients were evaluated for the predisposing factors. Results: Out of 100 children with acute severe asthma, the predominant age group was between 5 and 10 years (68%). Boys are more commonly affected than girls in the ratio of 1:1.2. The most common predisposing factors were family history of asthma (60%), atopy (32%), and dermatitis (23%). The common risk factors responsible for acute exacerbations were viral infections (83%), poor drug compliance (68%), and exposure to house dust (61%). 55% of the children had acute exacerbation during the winter season. The common comorbid conditions were rhinosinusitis (35%), obesity (23%), and gastroesophageal reflux (9%). Eosinophilia was seen in 62% of the children with acute severe asthma. Conclusion: In the present study, majority of the asthmatics were males and belonged to urban area. Viral infections were the predominant factor for exacerbations and others like family, and previous history of atopy/allergic rhinitis/dermatitis, food allergy, indoor and outdoor pollution, seasonal variations, and comorbid conditions like obesity and rhinosinusitis were the common predisposing risk factors

Kondo Effect in Fermi Systems with a Gap: A Renormalization Group Study

We present the results of a Wilson Renormalization Group study of the single-impurity Kondo and Anderson models in a system with a gap in the conduction electron spectrum. The behavior of the impurity susceptibility and the zero-frequency response function, $T>$ are discussed in the cases with and without particle-hole symmetry. In addition, for the asymmetric Anderson model the correlation functions, $<\vec S \cdot\vec \sigma (0)>$,$$, and$$ are computed.Comment: 10 pages, 10 figure