1,092 research outputs found

    Large parallel and perpendicular electric fields on electron spatial scales in the terrestrial bow shock

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    Large parallel (\leq 100 mV/m) and perpendicular (\leq 600 mV/m) electric fields were measured in the Earth's bow shock by the vector electric field experiment on the Polar satellite. These are the first reported direct measurements of parallel electric fields in a collisionless shock. These fields exist on spatial scales comparable to or less than the electron skin depth (a few kilometers) and correspond to magnetic field-aligned potentials of tens of volts and perpendicular potentials up to a kilovolt. The perpendicular fields are amongst the largest ever measured in space, with energy densities of ϵ0E2/nkbTe\epsilon_0 E^2/ n k_b T_e of order 10%. The measured parallel electric field implies that the electrons can be demagnetized, which may result in stochastic (rather than coherent) electron heating

    More and More Restrictive-But Not Always Populist: Explaining Variation in the British Conservative Party's Stance on Immigration and Asylum

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    This is the Author's Accepted Manuscript of an article published in the Journal of Contemporary European Studies Vol. 21, Iss. 1, copyright Taylor & Francis 2013, available online at: http://www.tandfonline.com/10.1080/14782804.2013.766474Centre-right parties are commonly inclined towards appeals and policies on immigration that are both restrictive in nature and populist in tone-in part because this is what they believe in, in part because it affords them an electoral advantage over their rivals on the centre-left. One would expect, however, that the extent to which they focus on immigration and asylum will vary according to public opinion, according to who leads them, and according to whether they are in government or in opposition. This would appear to be the case for the British Conservative Party, but the relationship is not an entirely consistent one. Moreover, while the Party has, for half a century, pursued ever more restrictive policies, the extent to which it has couched its approach in populist rhetoric varies considerably over time-and not always in line with the severity of its stance on immigration. The reason for this lies partly in the social and economic liberalism of some of its leaders (and in their related concern to act 'responsibly' on race and immigration) but also in their anxiety not to alienate key sections of the middle classes who must be persuaded to support the Party if it is to win elections. These considerations are likely to weigh heavily with other centre-right parties, too. © 2013 Copyright Taylor and Francis Group, LLC

    Spacecraft charging and ion wake formation in the near-Sun environment

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    A three-dimensional (3-D), self-consistent code is employed to solve for the static potential structure surrounding a spacecraft in a high photoelectron environment. The numerical solutions show that, under certain conditions, a spacecraft can take on a negative potential in spite of strong photoelectron currents. The negative potential is due to an electrostatic barrier near the surface of the spacecraft that can reflect a large fraction of the photoelectron flux back to the spacecraft. This electrostatic barrier forms if (1) the photoelectron density at the surface of the spacecraft greatly exceeds the ambient plasma density, (2) the spacecraft size is significantly larger than local Debye length of the photoelectrons, and (3) the thermal electron energy is much larger than the characteristic energy of the escaping photoelectrons. All of these conditions are present near the Sun. The numerical solutions also show that the spacecraft's negative potential can be amplified by an ion wake. The negative potential of the ion wake prevents secondary electrons from escaping the part of spacecraft in contact with the wake. These findings may be important for future spacecraft missions that go nearer to the Sun, such as Solar Orbiter and Solar Probe Plus.Comment: 25 pages, 7 figures, accepted for publication in Physics of Plasma

    The Association of Early Dietary Supplementation with Vitamin E with the Incidence of Ulcerative Dermatitis in Mice on a C57BL/6 Background

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    The purpose of this study was to ascertain if prophylactic ingestion of a diet rich in vitamin E would prevent  or impede the development of ulcerative dermatitis in mice on a C57BL/6 background. Mice were fed after  weaning a standard mouse diet, vitamin E (99 IU/kg), or a mouse diet fortified with vitamin E (3000 IU/  kg). Cases of ulcerative dermatitis were recorded by individuals (i.e. aware of) the diet assignment. The  incidence of ulcerative dermatitis in a retrospective cohort of mice on standard diet was compared with the  group on the diet fortified with vitamin E. Age was associated with ulcerative dermatitis in standard diet  and vitamin E fortified diet groups, r = 0.43, p-value < 0.0001 and r = 0.18, p-value < 0.02, respectively.  The average age of incidence for ulcerative dermatitis in the mice fed the standard diet was 89 weeks and  for the mice fed the vitamin E diet it was 41 weeks. The unadjusted odds ratio comparing the incidence of  ulcerative dermatitis between the two diet groups was 4.6 with a 95% confidence interval of (2.44, 8.58),  x2 p-value < 0.0001. Therefore, there was an association between the diets and ulcerative dermatitis, with  the mice on the vitamin E fortified diet having almost five times the odds of having ulcerative dermatitis  compared with mice on the standard diet. Incidence of ulcerative dermatitis was not influenced by sex or  genotype. Our study results show that a diet fortified in vitamin E initiated at weaning does not prevent or  impede the development of ulcerative dermatitis in mice on a C57BL/6 background and on the contrary  accelerate development when administered to young mice.

    Purification and Characterization of a Mitogenic Lectin from Cephalosporium, a Pathogenic Fungus Causing Mycotic Keratitis

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    Ophthalmic mycoses caused by infectious fungi are being recognized as a serious concern since they lead to total blindness. Cephalosporium is one amongst several opportunistic fungal species implicated in ophthalmic infections leading to mycotic keratitis. A mitogenic lectin has been purified from the mycelia of fungus Cephalosporium, isolated from the corneal smears of a keratitis patient. Cephalosporium lectin (CSL) is a tetramer with subunit mass of 14 kDa, agglutinates human A, B, and O erythrocytes, and exhibits high affinity for mucin compared to fetuin and asialofetuin but does not bind to simple sugars indicating its complex sugar specificity. CSL showed strong binding to normal human peripheral blood mononuclear cells (PBMCs) to elicit mitogenic activity. The sugar specificity of the lectin and its interaction with PBMCs to exhibit mitogenic effect indicate its possible role in adhesion and infection process of Cephalosporium
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