scholarly journals Local conditions separating expansion from collapse in spherically symmetric models with anisotropic pressures

2013 ◽  
Vol 88 (4) ◽  
Author(s):  
José P. Mimoso ◽  
Morgan Le Delliou ◽  
Filipe C. Mena
2021 ◽  
Vol 36 (29) ◽  
Author(s):  
Joaquin Estevez-Delgado ◽  
Modesto Pineda Duran ◽  
Arthur Cleary-Balderas ◽  
Noel Enrique Rodríguez Maya ◽  
José Martínez Peña

Starting from a regular, static and spherically symmetric spacetime, we present a stellar model formed by two sources of ordinary and quintessence matter both with anisotropic pressures. The ordinary matter, with density [Formula: see text], is formed by a fluid with a state equation type Chaplygin [Formula: see text] for the radial pressure. And the quintessence matter, with density [Formula: see text], has a state equation [Formula: see text] for the radial pressure and [Formula: see text] for the tangential pressure with [Formula: see text]. The model satisfies the required conditions to be physically acceptable and additionally the solution is potentially stable, i.e. [Formula: see text] according to the cracking concept, and it also satisfies the Harrison–Zeldovich–Novikov criteria. We describe in a graphic manner the behavior of the solution for the case in which the mass is [Formula: see text] and radius [Formula: see text][Formula: see text]km which matches the star EXO 1785-248, from where we obtain the maximum density [Formula: see text] for the values of the parameters [Formula: see text], [Formula: see text].


2015 ◽  
Vol 30 (27) ◽  
pp. 1550165
Author(s):  
S. Kalyana Rama

Unitarity of evolution in gravitational collapses implies existence of macroscopic stable horizonless objects. With such objects in mind, we study the effects of anisotropy of pressures on the stability of stars. We consider stars in four or higher dimensions and also stars in M theory made up of (intersecting) branes. Taking the stars to be static, spherically symmetric and the equations of state to be linear, we study “singular solutions” and the asymptotic perturbations around them. Oscillatory perturbations are likely to imply instability. We find that nonoscillatory perturbations, which may imply stability, are possible if an appropriate amount of anisotropy is present. This result suggests that it may be possible to have stable horizonless objects in four or any higher dimensions, and that anisotropic pressures may play a crucial role in ensuring their stability.


1977 ◽  
Vol 38 (02) ◽  
pp. 0399-0406 ◽  
Author(s):  
Peter N. Walsh ◽  
Richard E. Goldberg ◽  
Richard L. Tax ◽  
Larry E. Magargal

SummaryTo determine whether platelets play a role in the pathogenesis of retinal vein occlusion (RVO), platelets and coagulation were evaluated in 28 patients with RVO. Platelet coagulant activities concerned with the initiation and early stages of intrinsic coagulation were 2–4 fold increased in 9 patients with acute primary RVO but not in patients with acute secondary (10 patients) or chronic (9 patients) RVO. Platelet factor 3 activity, platelet aggregation, serotonin release by platelets and plasma coagulation were normal in all patients. Platelets may provide a trigger mechanism for venous thrombosis in the eye when local conditions permit.


2005 ◽  
Vol 35 (140) ◽  
pp. 379-392
Author(s):  
Helmut Dietrich

Poland accepted the alien and asylum policy of the European Union. But what does it mean, in the face of the fact that most of the refugees don´t want to sojourn a lot of time in Poland, but want to join their families or friends in Western Europe? How the transfer of policies does work, if the local conditions are quite different than in Germany or France? The answer seems to be the dramatization of the refugee situation in Poland, especially the adoption of emergency measures towards refugees of Chechnya.


2016 ◽  
pp. 91-118
Author(s):  
Peter Black

The Sonderdienst (Special Service) was an enforcement agency developed by German SS and Police authorities, specifically in the Lublin District of the so called Government General (central and southeastern German-occupied Poland) to assist in enforcing German occupation ordinances in the cities and particularly in the countryside, where lack of police personnel, ignorance of local conditions, and perceived fear of partisan attack discouraged a direct German police presence. After February 1941, the SS and Police relinquished control over the Sonderdienst to the German civilian occupation authorities. Under civilian authority, the Sonderdienst was deployed at the Kreis level, under command of the so-called German Stadt- and Kreishauptmänner in detachments of approximately 30 men to carry out administrative enforcement activities when the civilian authorities were unable to count or SS and police support. This article examines how the Sonderdienst highlights the dependence of German administration in the Government General on locally recruited auxiliaries, particularly in the countryside. The Sonderdienst was conceived, developed, expanded, and deployed within the context of a bitter battle between German civilian authorities and the SS/police apparatus over control of local executive police power. This is hardly new; yet the Government General is unusual in that the German civilian authorities were able to fight the SS to a draw on this issue. Since its formation followed the recruitment of the “ethnic” and ideological “cream” of the ethnic German population of occupied Poland into agencies such as the Selbstschutz, and the Waffen SS, the Sonderdienst represents an early effort of the National Socialist authorities to fashion an ethnically conscious and ideologically committed corps from young men of questionable, even dubious, German ancestry and heritage. Finally, this study reveals not only the complicity of the civilian authorities in Nazi crimes, but the link in German-occupied Poland between “routine” administrative duties, such as collecting fines for ordinance violations, and the brutal persecution and annihilation of groups targeted as enemies of the German Reich, such as the Polish Jews. Civilian administrators and SS and police authorities shared the “National Socialist consensus” in occupied Poland. They wanted to annihilate the Jews and the Polish intelligentsia, to exploit the labor potential of the Polish masses, and to turn the Government General into a region of German settlement. As a part of this vision, the Sonderdienst was to serve not only as a police executive, but as a political and cultural steppingstone to full acceptance into the German “racial community.” There is no question that, even in “routine” duties, the Sonderdienst participated, more or less willingly, in the implementation of the most evil racist policies of the National Socialist regime.


Author(s):  
J. Ure

The region contains half the area of exotic forest in New Zealand and the major industries dependent thereon. Both are expanding rapidly to meet promising export markets. Local conditions are particularly favourable for this form of primary production and continued expansion is expected.


2018 ◽  
Vol 11 (1) ◽  
pp. 4-26 ◽  
Author(s):  
Felix Fuhg

The emergence and formation of British working-class youth cultures in the 1960s were characterized by an ambivalent relationship between British identity, global culture and the formation of a multicultural society in the post-war decades. While national and local newspapers mostly reported on racial tensions and racially-motivated violence, culminating in the Notting Hill riots of 1958, the relationship between London's white working-class youth and teenagers with migration backgrounds was also shaped by a reciprocal, direct and indirect, personal and cultural exchange based on social interaction and local conditions. Starting from the Notting Hill Riots 1958, the article reconstructs places and cultural spheres of interaction between white working-class youth and teenagers from Caribbean communities in London in the 1960s. Following debates and discussions on race relations and the participation of black youth in the social life of London in the 1960s, the article shows that British working-class youth culture was affected in various ways by the processes of migration. By dealing with the multicultural dimension of the post-war metropolis, white working-class teenagers negotiated socio-economic as well as political changes, contributing in the process to an emergent, new image of post-imperial Britain.


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