1,907 research outputs found

    A Shock Wave Attached to a Pointed Obstacle in a Steady flow of a Dissociating Gas

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    A pointed obstacle is assumed symmetrically placed with respect to a uniform supersonic flow ahead of it. It is assumed that an oblique shock wave attached to the leading edge of the obstacle appears form the vertex so that the flow after the shock is along the surface of the obstacle. In this paper a relation between the curvature of an attached shock wave and that of a stream line is discovered. It is concluded that in a steady flow of an ideal dissociating gas, the stream lines at the rear of a straight attached shock wave are necessarily curved lines, whereas in an ordinary gas flow only a straight line flow is possible behind a straight shock

    Electronic screening and damping in magnetars

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    We calculate the screening of the ion-ion potential due to electrons in the presence of a large background magnetic field, at densities of relevance to neutron star crusts. Using the standard approach to incorporate electron screening through the one-loop polarization function, we show that the magnetic field produces important corrections both at short and long distances. In extreme fields, realized in highly magnetized neutron stars called magnetars, electrons occupy only the lowest Landau levels in the relatively low density region of the crust. Here our results show that the screening length for Coulomb interactions between ions can be smaller than the inter-ion spacing. More interestingly, we find that the screening is anisotropic and the screened potential between two static charges exhibits long range Friedel oscillations parallel to the magnetic field. This long-range oscillatory behavior is likely to affect the lattice structure of ions, and can possibly create rod-like structures in the magnetar crusts. We also calculate the imaginary part of the electron polarization function which determines the spectrum of electron-hole excitations and plays a role in damping lattice phonon excitations. We demonstrate that even for modest magnetic fields this damping is highly anisotropic and will likely lead to anisotropic phonon heat transport in the outer neutron star crust.Comment: 14 pages, 5 Figure

    OCT based evaluation of retinal changes in multiple sclerosis

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    Background: Optical coherence tomography is a non-invasive imaging technique routinely used in ophthalmology to visualize and quantify the layers of the retina. It also provides information on optic nerve head topography, peripapillary retinal nerve fibre layer thickness and macular volume which correlate with axonal loss. These measurements are of interest in optic neuropathies and in multiple sclerosis. The OCT parameters are now used as endpoints in neurologic clinical trials.Methods: A prospective study involving 30 patients of multiple sclerosis and equal number of age and sex matched controls were subjected to evaluation of retinal changes (peripapillary retinal nerve fiber layer and central macular thickness) using Zeiss Cirrus HD-OCT machine. The results collected were then subjected to statistical analysis.Results: Significant RNFL thinning was seen in patients of multiple sclerosis compared to the age and sex matched controls. Marked thinning was seen in superior and temporal quadrants of right eye (p value of 0.002 and 0.008 respectively) and all quadrants in left eye with a p value of < 0.001. Patients with multiple sclerosis for more than 5 yrs showed statistically significant RNFL thinning in the superior quadrant of right eye (p<.005), however, no such changes were seen in rest of the quadrants of right eye and in none of the quadrants of left eye Significant RNFL thinning was seen in the patients of multiple sclerosis without prior history of optic neuritis than patients with prior history of optic neuritis which was statistically significant with p value of .001.Conclusions: Patients with multiple sclerosis for more than 5 yrs showed statistically significant RNFL thinning in the superior quadrant of right eye (p<.005). Significant RNFL thinning was seen in the patients of multiple sclerosis without prior history of optic neuritis than patients with prior history of Optic neuritis which was statistically significant with p value of .001. No significant changes were seen in central macular thickness in multiple sclerosis compared to the controls which was corroborated by statistical analysis (p value of 0.37)

    Carica Papaya’s Anti-Diabetic and Anti-Cancer Properties – A Review

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    The Carica papaya originates from the Caricaceae family, and various members of this family have been used as treatments for a range of ailments. The perennial plant C. papaya, which is currently found over the whole tropical region, is thought to have originated in the southern region of Mexico. To assess the biological activity of distinct C. papaya sections, several scientific studies have been carried out. Since ancient times, the papaya plant's many components have been employed for medicinal purposes. In this article, the process of extracting Carica papaya leaves as well as the anti-cancer and anti-diabetic properties of papaya leaf activity were all things we wanted to assess. The information for this review paper, which focuses mostly on the therapeutic potential of papaya leaf extract was obtained via researching a collection of wider internet databases, including Google Scholar, PubMed, Science Direct, and Elsevier. The papaya plant, which has different parts such as fruit, leaves, seeds, bark, latex, and other substances, is very important in controlling the spread of illness. Alkaloids, glycosides, tannins, saponins, and flavonoids are just a few of the bioactive constituents in this, we focused on the papaya plant leaf's anti-cancer and anti-diabetic properties. The papaya has a wide range of therapeutic qualities. Papaya is a potent remedy, according to traditional beliefs. Biological activities have been the subject of much research. In the current review, all the pharmacological applications and activities of certain chemical components are discussed
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