6,659 research outputs found

    Pechukas-Yukawa approach to the evolution of the quantum state of a parametrically perturbed system

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    We consider the evolution of a quantum state of a Hamiltonian which is parametrically perturbed via a term proportional to the adiabatic parameter \lambda (t). Starting with the Pechukas-Yukawa mapping of the energy eigenvalues evolution on a generalised Calogero-Sutherland model of 1D classical gas, we consider the adiabatic approximation with two different expansions of the quantum state in powers of d\lambda/dt and compare them with a direct numerical simulation. We show that one of these expansions (Magnus series) is especially convenient for the description of non-adiabatic evolution of the system. Applying the expansion to the exact cover 3-satisfability problem, we obtain the occupation dynamics which provides insight on the population of states.Comment: 12 pages, 6 figure

    Stillbirth should be given greater priority on the global health agenda

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    Stillbirths are largely excluded from international measures of mortality and morbidity. Zeshan Qureshi and colleagues argue that stillbirth should be higher on the global health agenda

    Tocotrienols inhibit lipopolysaccharide-induced pro-inflammatory cytokines in macrophages of female mice

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    <p>Abstract</p> <p>Background</p> <p>Inflammation has been implicated in cardiovascular disease, and the important role of proteasomes in the development of inflammation and other macrophage functions has been demonstrated. Tocotrienols are potent hypocholesterolemic agents that inhibit β-hydroxy-β-methylglutaryl coenzyme A reductase activity, which is degraded via the ubiquitin-proteasome pathway. Our objective was to evaluate the effect of tocotrienols in reducing inflammation. Lipopolysaccharide (LPS) was used as a prototype for inflammation in murine RAW 264.7 cells and BALB/c female mice.</p> <p>Results</p> <p>The present results clearly demonstrate that α-, γ-, or δ-tocotrienol treatments inhibit the chymotrypsin-like activity of 20 S rabbit muscle proteasomes (> 50%; <it>P </it>< 0.05). Chymotrypsin, trypsin, and post-glutamase activities were decreased > 40% (<it>P </it>< 0.05) with low concentrations (< 80 μM), and then increased gradually with concentrations of (80 - 640 μM) in RAW 264.7 whole cells. Tocotrienols showed 9 - 33% (<it>P </it>< 0.05) inhibitions in TNF-α secretion in LPS-stimulated RAW 264.7 cells. Results of experiments carried out in BALB/c mice demonstrated that serum levels of TNF-α after LPS treatment were also reduced (20 - 48%; <it>P </it>< 0.05) by tocotrienols with doses of 1 and 10 μg/kg, and a corresponding rise in serum levels of corticosterone (19 - 41%; <it>P </it>< 0.05) and adrenocorticotropic hormone (81 - 145%; <it>P </it>< 0.02) was observed at higher concentrations (40 μM). Maximal inhibition of LPS-induced TNF-α was obtained with δ-tocotrienol (10 μg/kg). Low concentrations of δ-Tocotrienols (< 20 μM) blocked LPS-induced gene expression of TNF-α, IL-1β, IL-6 and iNOS (> 40%), while higher concentrations (40 μM) increased gene expression of the latter in peritoneal macrophages (prepared from BALB/c mice) as compared to control group.</p> <p>Conclusions</p> <p>These results represent a novel approach by using natural products, such as tocotrienols as proteasome modulators, which may lead to the development of new dietary supplements of tocotrienols for cardiovascular diseases, as well as others that are based on inflammation.</p

    Turbulent transport of material particles: An experimental study of finite size effects

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    We use an acoustic Lagrangian tracking technique, particularly adapted to measurements in open flows, and a versatile material particles generator (in the form of soap bubbles with adjustable size and density) to characterize Lagrangian statistics of finite sized, neutrally bouyant, particles transported in an isotropic turbulent flow of air. We vary the size of the particles in a range corresponding to turbulent inertial scales and explore how the turbulent forcing experienced by the particles depends on their size. We show that, while the global shape of the intermittent acceleration probability density function does not depend significantly on particle size, the acceleration variance of the particles decreases as they become larger in agreement with the classical scaling for the spectrum of Eulerian pressure fluctuations in the carrier flow

    Treatment of cardiovascular risk factors, nitric oxide synthesis, and c-reactive protein using a combination therapy of vitamins and flavanoids [abstract]

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    Researchers at the University of Missouri Kansas City have studied the synergistic effects of a novel combination of vitamins and flavanoids on cardiovascular risk factors, C-reactive protein levels, and nitric oxide production in the human body. Clinical trial results showed a marked decrease in the patients' serum nitric oxide and C-reactive protein levels. In addition, Hypercholesterolemic human subjects showed significant reductions in their lipid parameters (except for HDL cholesterol), and all subjects showed increases in total antioxidant status. Potential Areas of Applications: * Use as a nutritional supplemen

    An epidemic of Dengue fever in Karachi--associated clinical manifestations

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    Dengue is a mosquito borne disease with worldwide distribution. Depending on virulence factors and host immune status, infection can manifest as a severe but non fatal viral syndrome or a rapidly progressive and a frequently fatal haemorrhagic fever. During the course of an outbreak of viral fever in Karachi, Pakistan from June, 1994 to September, 1995, we studied 145 cases admitted at the Aga Khan University Hospital. 43% of the cases were between the age group of 20-30 years, majority of these being male (75%). Amongst the clinical signs and symptoms, the most frequent findings were fever, vomiting and abdominal pain. Spontaneous hemorrhagic manifestations occurred in 66 patients and of these petechiae and mucosal bleed were the commonest, that is, 42% and 38% respectively. At presentation thrombocytopenia (platelet count \u3c or = 50,000) per cubic millimeter) was present in 78%, leucopenia (white cell count \u3c 4,000 per cubic millimeter) in 34%. Apart from one patient who died from hemorrhagic shock on the 5th day of admission, the remaining patients recovered and their platelet counts normalized on an average in 9 days. This is the first reported epidemic in Karachi of dengue infection

    Ground state magnetic structure of Mn3_3Ge

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    We have used spherical neutron polarimetry to investigate the magnetic structure of the Mn spins in the hexagonal semimetal Mn3_3Ge, which exhibits a large intrinsic anomalous Hall effect. Our analysis of the polarimetric data finds a strong preference for a spin structure with E1gE_{1g} symmetry relative to the D6hD_{6h} point group. We show that weak ferromagnetism is an inevitable consequence of the symmetry of the observed magnetic structure, and that sixth order anisotropy is needed to select a unique ground state
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