15,517 research outputs found
Constant entropy hybrid stars: a first approximation of cooling evolution
We aim to study the possibility of a hadron-quark phase transition in the
interior of neutron stars, taking into account different schematic evolutionary
stages at finite temperature. We also discuss the strange quark matter
stability in the quark matter phase. Furthermore, we aim to analyze the
astrophysical properties of hot and cold hybrid stars, considering the
constraint on maximum mass given by the pulsars J1614-2230 and J0348+0432. We
have developed a computational code to construct semi-analytical hybrid
equations of state at fixed entropy per baryon and to obtain different families
of hybrid stars. An analytical approximation of the Field Correlator Method is
developed for the quark matter equation of state. For the hadronic equation of
state we use a table based on the relativistic mean field theory, without
hyperons. We solved the relativistic structure equations of hydrostatic
equilibrium and mass conservation for hybrid star configurations. For the
different equations of state obtained, we calculated the stability window for
the strange quark matter, lepton abundances, temperature profiles and contours
profiles for the maximum mass star depending on the parameters of the Field
Correlator Method. We also computed the mass-radius and gravitational
mass-baryonic mass relationships for different hybrid star families. We have
analyzed different stages of hot hybrid stars as a first approximation of the
cooling evolution of neutron stars with quark matter cores. We obtain cold
hybrid stars with maximum masses for different combinations of
the Field Correlator Method parameters. In addition, our study based on the
gravitational mass - baryonic mass plane shows a late phase transition between
hadronic and quark matter during the proto-hybrid star evolution, in contrast
with previous studies of proto-neutron stars.Comment: 12 pages, 14 figures, published in A&A 601, A21 (2017
Manajemen Kelompok Tani Petani Sayuran dalam Mendukung Ketahanan Pangan Kota Banjarbaru
Banjarbaru Municipality, from a spatial perspective, has a strategic role as a primary node of commodities distribution chain in South Kalimantan Province, because it is located between two main consumption centers, that are: Banjarmasin (the biggest consumption center) and Martapura. Beside as a consumption center, Banjarbaru also plays as an agricultural production center, especially vegetables. The study is purposed to know the management of the vegetable farmer group in order to promote food security in Banjarbaru Municipality. The population in the study was vegetable farmer groups. The samples were selected trough random sampling method. Generally, the management of the vegetable farmer group is in good condition (77.84%), planning (64.66%), organizing (85.89%), actuating (77.13%), and evaluation (65.55%). This shows that farmer group management able to support food security in Banjarbaru. For better management in a vegetable farmer group, it is suggested to increase the capability of planning in yields processing and marketing; and in recording farm activities
Dirichlet's and Thomson's principles for non-selfadjoint elliptic operators with application to non-reversible metastable diffusion processes
We present two variational formulae for the capacity in the context of
non-selfadjoint elliptic operators. The minimizers of these variational
problems are expressed as solutions of boundary-value elliptic equations. We
use these principles to provide a sharp estimate for the transition times
between two different wells for non-reversible diffusion processes. This
estimate permits to describe the metastable behavior of the system
Fractional charges in pyrochlore lattices
A pyrochlore lattice is considered where the average electron number of
electrons per site is half--integer, concentrating on the case of exactly half
an electron per site. Strong on-site repulsions are assumed, so that all sites
are either empty or singly occupied. Where there are in addition strong
nearest--neighbour repulsions, a tetrahedron rule comes into effect, as
previously suggested for magnetite. We show that in this case, there exist
excitations with fractional charge (+/-) e/2. These are intimately connected
with the high degeneracy of the ground state in the absence of kinetic energy
terms. When an additional electron is inserted into the system, it decays into
two point like excitations with charge -e/2, connected by a Heisenberg spin
chain which carries the electron's spin.Comment: 10 pages, 4 eps figures. To appear in Decemeber issue of Annalen der
Physi
Praktik Senam Hamil Hubungannya dengan Kelancaran Proses Persalinan
Maternal Mortality Rate (MMR) in Indonesia is higher than other countries, even among Asian countries. Exercise during pregnancy is the one of method to prepare delivery process and further is to prevent maternal death. The objective of this research is to analyze relationship between knowledge and practice of pregnancy exercise, also relationship between practice of pregnancy exercise and delivery process. This was a cross sectional research. Moreover, the population involve in this research were all primi para (mother that having first pregnancy) that recorded at Jagir Public Health Service Centre in Surabaya. The samples were taken by simple random sampling method. Furthermore, the relationship among variables was analyzed using chi square and fisher exact test. The result shows that there was no relationship betweenknowledge and practice of pregnancy exercise (p = 0.060), but there was a relationship between practice of pregnancy exercise and delivery process (p = 0.000). According to result of the research, its suggested that health promotion by doing pregnancy exercise should be developed because it can prepare physically and psychologically of delivery process and reduce the risk of maternal death.Key words: knowledge, pregnancy exercise, delivery proces
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