8,042 research outputs found
A note on the cylindrical collapse of counter-rotating dust
We find analytical solutions describing the collapse of an infinitely long
cylindrical shell of counter-rotating dust. We show that--for the classes of
solutions discussed herein--from regular initial data a curvature singularity
inevitably develops, and no apparent horizons form, thus in accord with the
spirit of the hoop conjecture.Comment: 8 pages, LaTeX, ijmpd macros (included), 1 eps figure; accepted for
publication in Int. J. Mod. Phys.
No-horizon theorem for spacetimes with spacelike G1 isometry groups
We consider four-dimensional spacetimes which obey the
Einstein equations , and admit a global spacelike
isometry group. By means of dimensional reduction and local
analyis on the reduced (2+1) spacetime, we obtain a sufficient condition on
which guarantees that cannot contain apparent
horizons. Given any (3+1) spacetime with spacelike translational isometry, the
no-horizon condition can be readily tested without the need for dimensional
reduction. This provides thus a useful and encompassing apparent horizon test
for -symmetric spacetimes. We argue that this adds further evidence
towards the validity of the hoop conjecture, and signals possible violations of
strong cosmic censorship.Comment: 8 pages, LaTeX, uses IOP package; published in Class. Quantum Gra
Sistema de produção de leite para as mesorregiões metropolitana de Belém e Nordeste paraense.
Strong curvature singularities in quasispherical asymptotically de Sitter dust collapse
We study the occurrence, visibility, and curvature strength of singularities
in dust-containing Szekeres spacetimes (which possess no Killing vectors) with
a positive cosmological constant. We find that such singularities can be
locally naked, Tipler strong, and develop from a non-zero-measure set of
regular initial data. When examined along timelike geodesics, the singularity's
curvature strength is found to be independent of the initial data.Comment: 16 pages, LaTeX, uses IOP package, 2 eps figures; accepted for
publication in Class. Quantum Gra
Food Waste in Public Food Service Sector-Surplus and Leftovers
Food waste occurs at various stages of the food supply chain, starting from the production stage on farms to processing, distribution, and consumption. It is an important global problem that has social, environmental, ethical, and economic costs. The present work aims to discuss the differences in waste generated from surpluses or leftovers, the monitoring systems of food waste in public food services, and the good practices to reduce food waste. Besides the accessible knowledge about reducing waste, tonnes of food were daily discarded and wasted. To achieve a sustainable food system, food waste must be reduced significantly. Collaborative efforts are necessary to achieve significant reductions in food waste for achieving SDG 12.3 in public food services. Thus, policies that support or enforce larger implementation of best practices are needed. Knowledge about food waste is important to change attitudes and behaviors toward surplus food and leftovers. Some best practices can include promoting awareness campaigns to educate staff about the impact of food waste and the best practices to reduce it, including information on proper storage, portion control, and meal planning; implementing inventory management systems; donating surplus food via collaboration with food banks and charities; optimizing portion sizes, ensuring they are adequate and manageable for customers, reducing the likelihood of leftover food on the plate; allowing customers to order smaller quantities or share a meal; providing packaging to allow customers take their leftovers home for later consumption. The procedures to be adopted by public food services should provide guidance for the selection of products that can be donated. However, specific temperature requirements depending on the food category should be complied with. This paper enlarges the understanding of surpluses and leftovers and the best practices that could be implemented in public food services to minimize food waste.The participation of CG is supported by FCT/UIDB/04033/2020. The participation of FN is supported by FCT UIDB/00616/2020 and UIDP/00616/2020. The participation of SS and CS were supported by the projects UIDB/CVT/00772/2020 and LA/P/0059/2020 funded by the Portuguese Foundation for Science and Technology (FCT). CG, FN and CS would like to thank to project I & D AgriFood XXI, operation NORTE-01-0145-FEDER43 000041, co-funded by European Regional Development Fund (FEDER) through NORTE 2020 (Programa Operacional Regional do Norte 2014/2020)
Caracterização do sistema de produção de leite predominante no sudeste paraense.
Perfil da produção; O produtor; A propriedade; Terras; Benfeitorias, máquinas e equipamentos; Sistema de produção; Composição do rebanho; Alimentação do rebanho; Manejo do rebanho; Produção e produtividade; Coeficientes zootécnicos; Recursos humanos; Receita bruta; Comercialização; Aquisição de insumos; Economia da produção.bitstream/item/63562/1/Oriental-Doc142.PD
Impacto da insulinoterapia prévia no prognóstico dos pacientes diabéticos com sÃndromes coronárias agudas
Impact of previous insulin therapy on the prognosis of diabetic patients with acute coronary syndrome
Different faces of the phantom
The SNe type Ia data admit that the Universe today may be dominated by some
exotic matter with negative pressure violating all energy conditions. Such
exotic matter is called {\it phantom matter} due to the anomalies connected
with violation of the energy conditions. If a phantom matter dominates the
matter content of the universe, it can develop a singularity in a finite future
proper time. Here we show that, under certain conditions, the evolution of
perturbations of this matter may lead to avoidance of this future singularity
(the Big Rip). At the same time, we show that local concentrations of a phantom
field may form, among other regular configurations, black holes with
asymptotically flat static regions, separated by an event horizon from an
expanding, singularity-free, asymptotically de Sitter universe.Comment: 6 pages, presented at IRGAC 2006, Barcelona, 11-15 July 200
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