2,288 research outputs found
Vacuum solutions with nontrivial boundaries for the Einstein-Gauss-Bonnet theory
The classification of certain class of static solutions for the
Einstein-Gauss-Bonnet theory in vacuum is presented. The spacelike section of
the class of metrics under consideration is a warped product of the real line
with a nontrivial base manifold. For arbitrary values of the Gauss-Bonnet
coupling, the base manifold must be Einstein with an additional scalar
restriction. The geometry of the boundary can be relaxed only when the
Gauss-Bonnet coupling is related with the cosmological and Newton constants, so
that the theory admits a unique maximally symmetric solution. This additional
freedom in the boundary metric allows the existence of three main branches of
geometries in the bulk, containing new black holes and wormholes in vacuum.Comment: Prepared for the proceedings of the 7th Alexander Friedmann
International Seminar on Gravitation and Cosmology, July 2008, Joao Pessoa,
Brasil. 4 pages, References adde
Applications of M.G. Krein's Theory of Regular Symmetric Operators to Sampling Theory
The classical Kramer sampling theorem establishes general conditions that
allow the reconstruction of functions by mean of orthogonal sampling formulae.
One major task in sampling theory is to find concrete, non trivial realizations
of this theorem. In this paper we provide a new approach to this subject on the
basis of the M. G. Krein's theory of representation of simple regular symmetric
operators having deficiency indices (1,1). We show that the resulting sampling
formulae have the form of Lagrange interpolation series. We also characterize
the space of functions reconstructible by our sampling formulae. Our
construction allows a rigorous treatment of certain ideas proposed recently in
quantum gravity.Comment: 15 pages; v2: minor changes in abstract, addition of PACS numbers,
changes in some keywords, some few changes in the introduction, correction of
the proof of the last theorem, and addition of some comments at the end of
the fourth sectio
Effects of patch size and number within a simple model of patchy colloids
We report on a computer simulation and integral equation study of a simple
model of patchy spheres, each of whose surfaces is decorated with two opposite
attractive caps, as a function of the fraction of covered attractive
surface. The simple model explored --- the two-patch Kern-Frenkel model ---
interpolates between a square-well and a hard-sphere potential on changing the
coverage . We show that integral equation theory provides quantitative
predictions in the entire explored region of temperatures and densities from
the square-well limit down to . For smaller
, good numerical convergence of the equations is achieved only at
temperatures larger than the gas-liquid critical point, where however integral
equation theory provides a complete description of the angular dependence.
These results are contrasted with those for the one-patch case. We investigate
the remaining region of coverage via numerical simulation and show how the
gas-liquid critical point moves to smaller densities and temperatures on
decreasing . Below , crystallization prevents the
possibility of observing the evolution of the line of critical points,
providing the angular analog of the disappearance of the liquid as an
equilibrium phase on decreasing the range for spherical potentials. Finally, we
show that the stable ordered phase evolves on decreasing from a
three-dimensional crystal of interconnected planes to a two-dimensional
independent-planes structure to a one-dimensional fluid of chains when the
one-bond-per-patch limit is eventually reached.Comment: 26 pages, 11 figures, J. Chem. Phys. in pres
On the habitat use of the Neotropical whip spider Charinus asturius (Arachnida: Amblypygi)
The non-random occupation of habitats is termed habitat selection. Some species of whip spiders select trees with burrows at their base, while others use substrates such as rocks. Here, we investigated the habitat use by Charinus asturius Pinto-da-Rocha, Machado & Weygoldt, 2002, an endemic species of Ilhabela Island in Brazil. We found that C. asturius is more likely to be found under rocks that cover larger areas of substrate. Our results also suggest the existence of territorialism in C. asturius and show that C. asturius adults may be found again on the same rock a week later. Additionally, our data show that C. asturius is present in a greater area of Ilhabela than previously documented.Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) [2014/19191-3, 2015/01518-9]Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq) [133214/2015-0]Univ Sao Paulo, Escola Artes Ciencias & Humanidades, Lab Ecol Sensorial & Comportamento Artropodes, Rua Arlindo Bettio 1000, BR-03828000 Sao Paulo, SP, BrazilUniv Sao Paulo, Inst Biociencias, Programa Pos Grad Zool, Rua Matao 321,Travessa 14, BR-05508900 Sao Paulo, BrazilUniv Sao Paulo, Inst Psicol, Dept Psicol Expt, Ave Prof Mello de Morais,1721 Butanta, BR-05508030 Sao Paulo, SP, BrazilUniv Fed Sao Paulo, Programa Pos Grad Ecol & Evolucao, Rua Prof Artur Riedel 275, BR-09972270 Diadema, BrazilUniv Fed Sao Paulo, Programa Pos Grad Ecol & Evolucao, Rua Prof Artur Riedel 275, BR-09972270 Diadema, BrazilFAPESP: [2014/19191-3, 2015/01518-9]CNPq: [133214/2015-0]Web of Scienc
The class of n-entire operators
We introduce a classification of simple, regular, closed symmetric operators
with deficiency indices (1,1) according to a geometric criterion that extends
the classical notions of entire operators and entire operators in the
generalized sense due to M. G. Krein. We show that these classes of operators
have several distinctive properties, some of them related to the spectra of
their canonical selfadjoint extensions. In particular, we provide necessary and
sufficient conditions on the spectra of two canonical selfadjoint extensions of
an operator for it to belong to one of our classes. Our discussion is based on
some recent results in the theory of de Branges spaces.Comment: 33 pages. Typos corrected. Changes in the wording of Section 2.
References added. Examples added. arXiv admin note: text overlap with
arXiv:1104.476
Stretching and folding versus cutting and shuffling: An illustrated perspective on mixing and deformations of continua
We compare and contrast two types of deformations inspired by mixing
applications -- one from the mixing of fluids (stretching and folding), the
other from the mixing of granular matter (cutting and shuffling). The
connection between mechanics and dynamical systems is discussed in the context
of the kinematics of deformation, emphasizing the equivalence between stretches
and Lyapunov exponents. The stretching and folding motion exemplified by the
baker's map is shown to give rise to a dynamical system with a positive
Lyapunov exponent, the hallmark of chaotic mixing. On the other hand, cutting
and shuffling does not stretch. When an interval exchange transformation is
used as the basis for cutting and shuffling, we establish that all of the map's
Lyapunov exponents are zero. Mixing, as quantified by the interfacial area per
unit volume, is shown to be exponentially fast when there is stretching and
folding, but linear when there is only cutting and shuffling. We also discuss
how a simple computational approach can discern stretching in discrete data.Comment: REVTeX 4.1, 9 pages, 3 figures; v2 corrects some misprints. The
following article appeared in the American Journal of Physics and may be
found at http://ajp.aapt.org/resource/1/ajpias/v79/i4/p359_s1 . Copyright
2011 American Association of Physics Teachers. This article may be downloaded
for personal use only. Any other use requires prior permission of the author
and the AAP
Peranan Sektor Pertanian terhadap Perekonomian di Kabupaten Minahasa Selatan
The aim of this research is to known the role of agricultural sector in South Minahasa Regency. The role was measured by sector position analysis and is the agriculture subsector was the base sector or nonbase by seeing the contribution of the agricultural sectorto the farming of Gross Regional Domestic Product in South Minahasa Regency. The data that has been used in this research was the secondary data by the Central Statistic Board of North Sulawesi Province, also the Agricultural and Livestock Service of South Minahasa Regency. The result of this research shows that the agricultural sector was the biggest contributor in the forming of GDRP in South Minahasa Regency. By using location quotient (LQ) analysis, the agricultural sector was one of the base sectors in the other sectors of econonomics, while agriculture subsector which was the base subsector is the one-season horticulture plants subsector. Based on the result of Dinamic Location Quotient (DLQ) analysis, the agricultural sector was predicted still be the base sector of South Minahasa Regency for five years ahead. Furthemore, the prediction of the agricultural subsector that have the potention of becoming the base subsector in the future is food plants subsector, one-sesion horticulture plants subsector, a-year horticultural subsector etcetera, a-year plantation subsector, livestock subsector, the service of agricultural subsector and hunting, and the fisheries subsector
Does ratification of human-rights treaties have effects on population health?
Human-rights treaties indicate a country's commitment to human rights. Here, we assess whether ratification of human-rights treaties is associated with improved health and social indicators. Data for health (including HIV prevalence, and maternal, infant, and child [<5 years] mortalities) and social indicators (child labour, human development index, sex gap, and corruption index), gathered from 170 countries, showed no consistent associations between ratification of human-rights treaties and health or social outcomes. Established market economy states had consistently improved health compared with less wealthy settings, but this was not associated with treaty ratification. The status of treaty ratification alone is not a good indicator of the realisation of the right to health. We suggest the need for stringent requirements for ratification of treaties, improved accountability mechanisms to monitor compliance of states with treaty obligations, and financial assistance to support the realisation of the right to health
Towards the deformation quantization of linearized gravity
We present a first attempt to apply the approach of deformation quantization
to linearized Einstein's equations. We use the analogy with Maxwell equations
to derive the field equations of linearized gravity from a modified Maxwell
Lagrangian which allows the construction of a Hamiltonian in the standard way.
The deformation quantization procedure for free fields is applied to this
Hamiltonian. As a result we obtain the complete set of quantum states and its
discrete spectrum.Comment: 13 pages, no figures **preliminary entry **
Density Variations in the NW Star Stream of M31
The Pan Andromeda Archeological Survey (PAndAS) CFHT Megaprime survey of the
M31-M33 system has found a star stream which extends about 120 kpc NW from the
center of M31. The great length of the stream, and the likelihood that it does
not significantly intersect the disk of M31, means that it is unusually well
suited for a measurement of stream gaps and clumps along its length as a test
for the predicted thousands of dark matter sub-halos. The main result of this
paper is that the density of the stream varies between zero and about three
times the mean along its length on scales of 2 to 20 kpc. The probability that
the variations are random fluctuations in the star density is less than 10^-5.
As a control sample we search for density variations at precisely the same
location in stars with metallicity higher than the stream, [Fe/H]=[0, -0.5] and
find no variations above the expected shot noise. The lumpiness of the stream
is not compatible with a low mass star stream in a smooth galactic potential,
nor is it readily compatible with the disturbance caused by the visible M31
satellite galaxies. The stream's density variations appear to be consistent
with the effects of a large population of steep mass function dark matter
sub-halos, such as found in LCDM simulations, acting on an approximately 10Gyr
old star stream. The effects of a single set of halo substructure realizations
are shown for illustration, reserving a statistical comparison for another
study.Comment: ApJ revised version submitte
- …