703 research outputs found

    On the contribution of exchange interactions to the Vlasov equation

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    Exchange effects play an important role in determining the equilibrium properties of dense matter systems, as well as for magnetic phenomena. There exists an extensive literature concerning, e.g., the effects of exchange interactions on the equation of state of dense matter. Here, a generalization of the Vlasov equation to include exchange effects is presented allowing for electromagnetic mean fields, thus incorporating some of the dynamic effects due to the exchange interactions. Treating the exchange term perturbatively, the correction to classical Langmuir waves in plasmas is found, and the results are compared with previous work. It is noted that the relative importance of exchange effects scales similarly with density and temperature as particle dispersive effects, but that the overall magnitude is sensitive to the details of the specific problem. The implications of our results are discussed.Comment: 9 page

    Nonlinear wave interaction and spin models in the MHD regime

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    Here we consider the influence on the electron spin in the MHD regime. Recently developed models which include spin-velocity correlations are taken as a starting point. A theoretical argument is presented, suggesting that in the MHD regime a single fluid electron model with spin correlations is equivalent to a model with spin-up and spin-down electrons constituting different fluids, but where the spin-velocity correlations are omitted. Three wave interaction of 2 shear Alfven waves and a compressional Alfven wave is then taken as a model problem to evaluate the asserted equivalence. The theoretical argument turns out to be supported, as the predictions of the two models agree completely. Furthermore, the three wave coupling coefficients obey the Manley-Rowe relations, which give further support to the soundness of the models and the validity of the assumptions made in the derivation. Finally we point out that the proposed two-fluid model can be incorporated in standard Particle-In-Cell schemes with only minor modifications.Comment: 8 page

    Fluid moment hierarchy equations derived from gauge invariant quantum kinetic theory

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    The gauge invariant electromagnetic Wigner equation is taken as the basis for a fluid-like system describing quantum plasmas, derived from the moments of the gauge invariant Wigner function. The use of the standard, gauge dependent Wigner function is shown to produce inconsistencies, if a direct correspondence principle is applied. The propagation of linear transverse waves is considered and shown to be in agreement with the kinetic theory in the long wavelength approximation, provided an adequate closure is chosen for the macroscopic equations. A general recipe to solve the closure problem is suggested.Comment: 12 pages, 1 figur

    Regularizing velocity differences in time-lapse FWI using gradient mismatch information

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    We present a method for recovering time-lapse velocity changes using full waveform inversion (FWI). In a preprocessing step we invert for a single intermediate model by simultaneously minimizing the data misfit in the baseline and the monitor surveys. We record the individual FWI gradients corresponding to the baseline and the monitor datasets at each iteration of the inversion. Regions where these gradients consistently have opposing sign are likely to correspond to locations of time-lapse change. This insight is used to generate a spatially varying confidence map for time-lapse change. In a subsequent joint inversion we invert for baseline and monitor models while regularizing the difference between the models with this spatially varying confidence map. Unlike double difference full waveform inversion (DDFWI) we do not require identical source and receiver positions in the baseline and monitor surveys

    Effects of the gg-factor in semi-classical kinetic plasma theory

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    A kinetic theory for spin plasmas is put forward, generalizing those of previous authors. In the model, the ordinary phase space is extended to include the spin degrees of freedom. Together with Maxwell's equations, the system is shown to be energy conserving. Analysing the linear properties, it is found that new types of wave-particle resonances are possible, that depend directly on the anomalous magnetic moment of the electron. As a result new wave modes, not present in the absence of spin, appear. The implications of our results are discussed.Comment: 4 pages, two figures, version to appear in Physical Review Letter

    Morphine Suppository versus Indomethacin Suppository in the Management of Renal Colic: Randomized Clinical Trial

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    Background. Renal colic is a medical emergency due to the rapid onset and devastating nature of its pain. Opioids and nonsteroidal anti-inflammatory drugs (NSAIDs) are both used as first-line choices in its management. Aim. This study aimed to compare the efficacy and safety of opioids and NSAIDs in the management of acute renal colic. Methods. One hundred and fifty-eight patients were divided into two groups (n=79) and received either 10 mg morphine or 100 mg indomethacin suppositories. The severity of pain was measured using verbal numeric rating scale at baseline and 20, 40, 60, and 90 minutes after the administration of analgesics. Drug side effects as well as patients' vital signs were also recorded. Results. The mean decrease in the pain score during the first 20 minutes was significantly higher among those who received morphine suppository. However, no significant difference was observed between the two groups regarding the mean decrease in pain score during the first 40, 60, and 90 minutes after the admission. Prevalence of drug side effects or changes in the vital signs was not significantly different between the two groups. Conclusions. Morphine suppositories seem to be more efficient in achieving rapid pain relief comparing to indomethacin. © 2016 Forough Zamanian et al

    Spin induced nonlinearities in the electron MHD regime

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    We consider the influence of the electron spin on the nonlinear propagation of whistler waves. For this purpose a recently developed electron two-fluid model, where the spin up- and down populations are treated as different fluids, is adapted to the electron MHD regime. We then derive a nonlinear Schrodinger equation for whistler waves, and compare the coefficients of nonlinearity with and without spin effects. The relative importance of spin effects depend on the plasma density and temperature as well as the external magnetic field strength and the wave frequency. The significance of our results to various plasmas are discussed.Comment: 5 page

    Drug-induced skin reactions: A 2-year study

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    Background: The aim of this study was to analyze the clinical characteristics of patients with adverse cutaneous drug reactions, which occur when a medicinal product results in cutaneous morbidity. Methods: The study included 308 patients who were diagnosed as having an adverse cutaneous drug reaction during the study period (2007�2009). In 84 cases, histopathologic examination of skin biopsies were also performed. Results: Patients with drug reactions were found to be more commonly female (63) than male (37). Beta-lactam antibiotics were found to be the most frequent cause of adverse cutaneous drug reactions (42.7), followed by non-steroidal anti-infammatory drugs (16.5). Acute urticaria was the most common clinical presentation (59.2) followed by fxed drug eruptions (18.5), and maculopapular eruptions (14.9). Conclusion: Adverse cutaneous drug reactions in our study population were mainly induced by beta-lactam antibiotics and non-steroidal anti-inflammatory drugs. The most common forms of cutaneous adverse drug reactions were found to be acute urticaria, fxed drug eruptions, and maculopapular rashes. © 2015 Farshchian et al

    Spin and magnetization effects in plasmas

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    We give a short review of a number of different models for treating magnetization effects in plasmas. In particular, the transition between kinetic models and fluid models is discussed. We also give examples of applications of such theories. Some future aspects are discussed.Comment: 18 pages, 1 figure. To appear in Plasma Physics and Controlled Fusion, Special Issue for the 37th ICPP, Santiago, Chil

    The Potential of Algae in Treating Celiac Disease

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    Compounds found in algae, such as bioactive substances, sulfated polysaccharides, and polyunsaturated fatty acids, have been found to have positive effects on the immune system. Previous research has shown that algae can also benefit digestive system disorders. They possess antioxidant and anti-inflammatory properties and can influence the balance of gut microbiota and maintain the integrity of the intestinal lining. Celiac disease (CD), a disorder caused by an abnormal immune response to gluten, results in inflammation and damage to the intestinal lining, leading to problems with nutrient absorption. Although a lifelong gluten-free diet is the only treatment option for this disease, it is challenging to adhere to. Therefore, recent studies have focused on finding supplementary or alternative therapies for celiac disease patients. Traditional medical treatments, like anti-inflammatory and biological drugs, are associated with significant side effects and are not suitable for supplementary therapy for this group of patients. Algae shows promise as a potential research area for treating CD; however, their specific effects on this condition have not been widely studied. The aim of this study was to gather current information and draw attention to the potential use of algae extracts in treating CD to encourage further research in this field
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