2,194 research outputs found
Alpha 1 antitrypsin gene: A case-control study in chronic obstructive pulmonary disease
Alpha-1 antitrypsin (AAT) deficiency is an inherited disorder that causes low levels of, or no AAT in the blood. The most common illness in adults with AAT deficiency is lung disease during the third and fourth decades of life. Most commonly, it is associated with chronic obstructive pulmonary disease (COPD). Mutations in the protease inhibitor (PI) gene, located on chromosome 14, are associated with this genetic disorder. The Z protein is due to a single amino acid substitution of 342 glutamine lysine. Although cigarette smoking is the main environmental risk factor, only about 15% of smokers develop clinically significant disease suggesting other influences on disease expression. The study included hospital based age and sex matched 100 cases of COPD and 100 controls without COPD recruited from Christian Medical Centre, Jorhat, Assam. These cases were recruited from February 2009 to December 2009. Subjects were included in the COPD group on the basis of lung function test. DNA extraction was done by DNA extraction kit and amplification for AAT gene was done by site directed mutagenesis polymerase chain reaction (PCR) method as described by Tazellar et al. (1992). We found that smoking was the prior cause of COPD. A1AT deficiency is not prevalent in our population subset but certain other genes could be the attributable factor for COPD.Key words: Alpha 1-antitrypsin, chronic obstructive pulmonary disorder (COPD)
Solutions of Several Coupled Discrete Models in terms of Lame Polynomials of Order One and Two
Coupled discrete models abound in several areas of physics. Here we provide
an extensive set of exact quasiperiodic solutions of a number of coupled
discrete models in terms of Lame polynomials of order one and two. Some of the
models discussed are (i) coupled Salerno model, (ii) coupled Ablowitz-Ladik
model, (iii) coupled saturated discrete nonlinear Schrodinger equation, (iv)
coupled phi4 model, and (v) coupled phi6 model. Furthermore, we show that most
of these coupled models in fact also possess an even broader class of exact
solutions.Comment: 31 pages, to appear in Pramana (Journal of Physics) 201
Exercise cardiovascular magnetic resonance: feasibility and development of biventricular function and great vessel flow assessment, during continuous exercise accelerated by Compressed SENSE: preliminary results in healthy volunteers
Purpose
Exercise cardiovascular magnetic resonance (Ex-CMR) typically requires complex post-processing or transient exercise cessation, decreasing clinical utility. We aimed to demonstrate the feasibility of assessing biventricular volumes and great vessel flow during continuous in-scanner Ex-CMR, using vendor provided Compressed SENSE (C-SENSE) sequences and commercial analysis software (Cvi42).
Methods
12 healthy volunteers (8-male, age: 35â±â9 years) underwent continuous supine cycle ergometer (Lode-BV) Ex-CMR (1.5T Philips, Ingenia). Free-breathing, respiratory navigated C-SENSE short-axis cines and aortic/pulmonary phase contrast magnetic resonance (PCMR) sequences were validated against clinical sequences at rest and used during low and moderate intensity Ex-CMR. Optimal PCMR C-SENSE acceleration, C-SENSE-3 (CS3) vs C-SENSE-6 (CS6), was further investigated by image quality scoring. Intra-and inter-operator reproducibility of biventricular and flow indices was performed.
Results
All CS3 PCMR image quality scores were superior (pââ0.93). During Ex-CMR, biventricular end-diastolic volumes (EDV) remained unchanged, except right-ventricular EDV decreasing at moderate exercise. Biventricular ejection-fractions increased at each stage. Exercise biventricular cine and PCMR stroke volumes correlated very strongly (rââ„â0.9), demonstrating internal validity. Intra-observer reproducibility was excellent, co-efficient of variance (COV)â<â10%. Inter-observer reproducibility was excellent, except for resting right-ventricular, and exercise bi-ventricular end-systolic volumes which were good (COV 10â20%).
Conclusion
Biventricular function, aortic and pulmonary flow assessment during continuous Ex-CMR using CS3 sequences is feasible, reproducible and analysable using commercially available software
Chronic nonpuerperal uterine inversion and necrosis: a case report
<p>Abstract</p> <p><b>Introduction</b></p> <p>Inversion of the non-pregnant uterus is rare.</p> <p><b>Case presentation</b></p> <p>A 56-year-old African American woman presented to our emergency center with complaints of a mass protruding from her vagina. She subsequently underwent vaginal myomectomy, abdominal hysterectomy and bilateral salpingo-oophorectomy. Pathologic examination revealed a necrotic fibroid and endometrium. At the time of laparotomy an inverted uterus was diagnosed when a 3 cm dimple containing bilateral round ligaments, infundibulopelvic ligaments and bladder was observed.</p> <p>Conclusion</p> <p>Chronic nonpuerperal inversion of the uterus is rare. Infection should be suspected and appropriate broad spectrum antibiotics begun while planning surgery. An attempt at vaginal restoration and removal is difficult. Abdominal hysterectomy may be necessary taking care to locate the distal urinary collecting system.</p
Phenomenological Aspects of Gauge Mediation with Sequestered Supersymmetry Breaking in light of Dark Matter Detection
In a recent work, a model of gauge mediation with sequestered supersymmetry
(SUSY) breaking was proposed. In this model, the mass of the gravitino is
O(100) GeV without causing the flavor-changing neutral-current problem. In
contrast to traditional gauge mediation, the gravitino is not the lightest SUSY
particle and the neutralino is the candidate of the dark matter. In this paper,
we investigate phenomenological aspects of this model and discuss the
possibility of the direct detection of the dark matter. In particular, we focus
on the light neutralino case and find that the light-Higgsino scenario such as
the focus point is interesting, taking account of the recent CDMS result.Comment: 17 pages, 8 figures; v2:references added, some corrections;
v3:version accepted for publication in JHE
Evolution of Landau Levels into Edge States at an Atomically Sharp Edge in Graphene
The quantum-Hall-effect (QHE) occurs in topologically-ordered states of
two-dimensional (2d) electron-systems in which an insulating bulk-state
coexists with protected 1d conducting edge-states. Owing to a unique
topologically imposed edge-bulk correspondence these edge-states are endowed
with universal properties such as fractionally-charged quasiparticles and
interference-patterns, which make them indispensable components for QH-based
quantum-computation and other applications. The precise edge-bulk
correspondence, conjectured theoretically in the limit of sharp edges, is
difficult to realize in conventional semiconductor-based electron systems where
soft boundaries lead to edge-state reconstruction. Using scanning-tunneling
microscopy and spectroscopy to follow the spatial evolution of bulk
Landau-levels towards a zigzag edge of graphene supported above a graphite
substrate we demonstrate that in this system it is possible to realize
atomically sharp edges with no edge-state reconstruction. Our results single
out graphene as a system where the edge-state structure can be controlled and
the universal properties directly probed.Comment: 16 pages, 4 figure
Quantum fluctuations can promote or inhibit glass formation
The very nature of glass is somewhat mysterious: while relaxation times in
glasses are of sufficient magnitude that large-scale motion on the atomic level
is essentially as slow as it is in the crystalline state, the structure of
glass appears barely different than that of the liquid that produced it.
Quantum mechanical systems ranging from electron liquids to superfluid helium
appear to form glasses, but as yet no unifying framework exists connecting
classical and quantum regimes of vitrification. Here we develop new insights
from theory and simulation into the quantum glass transition that surprisingly
reveal distinct regions where quantum fluctuations can either promote or
inhibit glass formation.Comment: Accepted for publication in Nature Physics. 22 pages, 3 figures, 1
Tabl
Fully gapped topological surface states in BiSe films induced by a d-wave high-temperature superconductor
Topological insulators are a new class of materials, that exhibit robust
gapless surface states protected by time-reversal symmetry. The interplay
between such symmetry-protected topological surface states and symmetry-broken
states (e.g. superconductivity) provides a platform for exploring novel quantum
phenomena and new functionalities, such as 1D chiral or helical gapless
Majorana fermions, and Majorana zero modes which may find application in
fault-tolerant quantum computation. Inducing superconductivity on topological
surface states is a prerequisite for their experimental realization. Here by
growing high quality topological insulator BiSe films on a d-wave
superconductor BiSrCaCuO using molecular beam epitaxy,
we are able to induce high temperature superconductivity on the surface states
of BiSe films with a large pairing gap up to 15 meV. Interestingly,
distinct from the d-wave pairing of BiSrCaCuO, the
proximity-induced gap on the surface states is nearly isotropic and consistent
with predominant s-wave pairing as revealed by angle-resolved photoemission
spectroscopy. Our work could provide a critical step toward the realization of
the long sought-after Majorana zero modes.Comment: Nature Physics, DOI:10.1038/nphys274
Collapse of superconductivity in a hybrid tin-graphene Josephson junction array
When a Josephson junction array is built with hybrid
superconductor/metal/superconductor junctions, a quantum phase transition from
a superconducting to a two-dimensional (2D) metallic ground state is predicted
to happen upon increasing the junction normal state resistance. Owing to its
surface-exposed 2D electron gas and its gate-tunable charge carrier density,
graphene coupled to superconductors is the ideal platform to study the
above-mentioned transition between ground states. Here we show that decorating
graphene with a sparse and regular array of superconducting nanodisks enables
to continuously gate-tune the quantum superconductor-to-metal transition of the
Josephson junction array into a zero-temperature metallic state. The
suppression of proximity-induced superconductivity is a direct consequence of
the emergence of quantum fluctuations of the superconducting phase of the
disks. Under perpendicular magnetic field, the competition between quantum
fluctuations and disorder is responsible for the resilience at the lowest
temperatures of a superconducting glassy state that persists above the upper
critical field. Our results provide the entire phase diagram of the disorder
and magnetic field-tuned transition and unveil the fundamental impact of
quantum phase fluctuations in 2D superconducting systems.Comment: 25 pages, 6 figure
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