79 research outputs found
Freely falling 2-surfaces and the quasi-local energy
We derive an expression for effective gravitational mass for any closed
spacelike 2-surface. This effective gravitational energy is defined directly
through the geometrical quantity of the freely falling 2-surface and thus is
well adapted to intuitive expectation that the gravitational mass should be
determined by the motion of test body moving freely in gravitational field. We
find that this effective gravitational mass has reasonable positive value for a
small sphere in the non-vacuum space-times and can be negative for vacuum case.
Further, this effective gravitational energy is compared with the quasi-local
energy based on the formalism of the General Relativity. Although some
gauge freedoms exist, analytic expressions of the quasi-local energy for vacuum
cases are same as the effective gravitational mass. Especially, we see that the
contribution from the cosmological constant is the same in general cases.Comment: 11 pages, no figures, REVTeX. Estimation of the effective mass of
small spheres in non-vaccum spacetime and Schwarzschild spacetime are added.
The negativity of the latter is discusse
Conserved charges for gravity with locally AdS asymptotics
A new formula for the conserved charges in 3+1 gravity for spacetimes with
local AdS asymptotic geometry is proposed. It is shown that requiring the
action to have an extremum for this class of asymptotia sets the boundary term
that must be added to the Lagrangian as the Euler density with a fixed weight
factor. The resulting action gives rise to the mass and angular momentum as
Noether charges associated to the asymptotic Killing vectors without requiring
specification of a reference background in order to have a convergent
expression. A consequence of this definition is that any negative constant
curvature spacetime has vanishing Noether charges. These results remain valid
in the limit of vanishing cosmological constant.Comment: 5 pages, 2 Columns, revtex. Last version for Phys. Rev. Let
Fractional differentiability of nowhere differentiable functions and dimensions
Weierstrass's everywhere continuous but nowhere differentiable function is
shown to be locally continuously fractionally differentiable everywhere for all
orders below the `critical order' 2-s and not so for orders between 2-s and 1,
where s, 1<s<2 is the box dimension of the graph of the function. This
observation is consolidated in the general result showing a direct connection
between local fractional differentiability and the box dimension/ local Holder
exponent. Levy index for one dimensional Levy flights is shown to be the
critical order of its characteristic function. Local fractional derivatives of
multifractal signals (non-random functions) are shown to provide the local
Holder exponent. It is argued that Local fractional derivatives provide a
powerful tool to analyze pointwise behavior of irregular signals.Comment: minor changes, 19 pages, Late
The Dark Energy Survey: Data Release 1
We describe the first public data release of the Dark Energy Survey, DES DR1, consisting of reduced single-epoch images, co-added images, co-added source catalogs, and associated products and services assembled over the first 3 yr of DES science operations. DES DR1 is based on optical/near-infrared imaging from 345 distinct nights (2013 August to 2016 February) by the Dark Energy Camera mounted on the 4 m Blanco telescope at the Cerro Tololo Inter-American Observatory in Chile. We release data from the DES wide-area survey covering ~5000 deg2 of the southern Galactic cap in five broad photometric bands, grizY. DES DR1 has a median delivered point-spread function of , r = 0.96, i = 0.88, z = 0.84, and Y = 090 FWHM, a photometric precision of \u3c1% in all bands, and an astrometric precision of 151 . The median co-added catalog depth for a 195 diameter aperture at signal-to-noise ratio (S/N) = 10 is g = 24.33, r = 24.08, i = 23.44, z = 22.69, and Y = 21.44 . DES DR1 includes nearly 400 million distinct astronomical objects detected in ~10,000 co-add tiles of size 0.534 deg2 produced from ~39,000 individual exposures. Benchmark galaxy and stellar samples contain ~310 million and ~80 million objects, respectively, following a basic object quality selection. These data are accessible through a range of interfaces, including query web clients, image cutout servers, jupyter notebooks, and an interactive co-add image visualization tool. DES DR1 constitutes the largest photometric data set to date at the achieved depth and photometric precision
Nuclear Clusters as a Probe for Expansion Flow in Heavy Ion Reactions at 10-15AGeV
A phase space coalescence description based on the Wigner-function method for
cluster formation in relativistic nucleus-nucleus collisions is presented. The
momentum distributions of nuclear clusters d,t and He are predicted for central
Au(11.6AGeV)Au and Si(14.6AGeV)Si reactions in the framework of the RQMD
transport approach. Transverse expansion leads to a strong shoulder-arm shape
and different inverse slope parameters in the transverse spectra of nuclear
clusters deviating markedly from thermal distributions. A clear ``bounce-off''
event shape is seen: the averaged transverse flow velocities in the reaction
plane are for clusters larger than for protons. The cluster yields
--particularly at low at midrapidities-- and the in-plane (anti)flow of
clusters and pions change if suitably strong baryon potential interactions are
included. This allows to study the transient pressure at high density via the
event shape analysis of nucleons, nucleon clusters and other hadrons.Comment: 38 pages, 9 figures, LaTeX type, eps used, subm. to Phys. Rev.
Theoretical Uncertainties and Phenomenological Aspects of Decay
We analyze uncertainties in the theoretical prediction for the inclusive
branching ratio . We find that the dominant
uncertainty in the leading order expression comes from its -dependence. We
discuss a next-to-leading order calculation of in
general terms and check to what extent the -dependence can be reduced in
such a calculation. We present constraints on the Standard and
Two-Higgs-Doublet Model parameters coming from the measurement of decay. The current theoretical uncertainties do not allow
one to definitively restrict the Standard Model parameters much beyond the
limits coming from other experiments. The bounds on the Two-Higgs-Doublet Model
remain very strong, though significantly weaker than the ones present in the
recent literature. In the Two-Higgs-Doublet Model case, the , and
processes are enough to give the most restrictive bounds in the
plane.Comment: 22 pages (including figures), MPI-Ph/93-77, TUM-T31-50/9
Genetic research: the role of citizens, public health and international stakeholders
Background: Genetic research has become an indispensable instrument for medical research, and the subjects involved have both divergent and convergent interests. Objective: The possibility of having more detailed genetic information undoubtedly offers benefits for the health of the subject, but could also pose risks and make the subject vulnerable to discrimination. Methods: The scientific community has viewed very favorably the public health utility of family history, in which data from a family whose members suffer from chronic pathologies is collected and filed, in order to develop a sort of “stratification of family risk.” Even though in the last decade the scientific and juridical literature has contributed greatly to the topic of biobanks, the perplexities that continue to surround this theme give the idea that current ethical protocols on research are inadequate. Results: Researchers, citizens, International stakeholders, mass media, Public Health and Governments play a key role in genetic research. It is obvious that the methods used for genetic research do not present intrinsic risks; they are much less dangerous than other activities of diagnosis and research. Before authorizing a research project, it is important to reflect on the responsibility and transparency of the studies to be conducted, and on the impact they may have on the interests of public health. Conclusion: We believe that the highest priority need is to develop a common language on the theme, as is the case in the sphere of clinical experimentation where rules of good clinical practice, albeit at times conflicting, have led to uniform convergences in the scientific world on the points to be actuated
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