Experimentally testing the standard cosmological model
Energy Technology Data Exchange (ETDEWEB)
Schramm, D.N. (Chicago Univ., IL (USA) Fermi National Accelerator Lab., Batavia, IL (USA))
1990-11-01
The standard model of cosmology, the big bang, is now being tested and confirmed to remarkable accuracy. Recent high precision measurements relate to the microwave background; and big bang nucleosynthesis. This paper focuses on the latter since that relates more directly to high energy experiments. In particular, the recent LEP (and SLC) results on the number of neutrinos are discussed as a positive laboratory test of the standard cosmology scenario. Discussion is presented on the improved light element observational data as well as the improved neutron lifetime data. alternate nucleosynthesis scenarios of decaying matter or of quark-hadron induced inhomogeneities are discussed. It is shown that when these scenarios are made to fit the observed abundances accurately, the resulting conclusions on the baryonic density relative to the critical density, {Omega}{sub b}, remain approximately the same as in the standard homogeneous case, thus, adding to the robustness of the standard model conclusion that {Omega}{sub b} {approximately} 0.06. This latter point is the deriving force behind the need for non-baryonic dark matter (assuming {Omega}{sub total} = 1) and the need for dark baryonic matter, since {Omega}{sub visible} < {Omega}{sub b}. Recent accelerator constraints on non-baryonic matter are discussed, showing that any massive cold dark matter candidate must now have a mass M{sub x} {approx gt} 20 GeV and an interaction weaker than the Z{sup 0} coupling to a neutrino. It is also noted that recent hints regarding the solar neutrino experiments coupled with the see-saw model for {nu}-masses may imply that the {nu}{sub {tau}} is a good hot dark matter candidate. 73 refs., 5 figs.
Experimentally testing the standard cosmological model
International Nuclear Information System (INIS)
Schramm, D.N.
1990-11-01
The standard model of cosmology, the big bang, is now being tested and confirmed to remarkable accuracy. Recent high precision measurements relate to the microwave background; and big bang nucleosynthesis. This paper focuses on the latter since that relates more directly to high energy experiments. In particular, the recent LEP (and SLC) results on the number of neutrinos are discussed as a positive laboratory test of the standard cosmology scenario. Discussion is presented on the improved light element observational data as well as the improved neutron lifetime data. alternate nucleosynthesis scenarios of decaying matter or of quark-hadron induced inhomogeneities are discussed. It is shown that when these scenarios are made to fit the observed abundances accurately, the resulting conclusions on the baryonic density relative to the critical density, Ω b , remain approximately the same as in the standard homogeneous case, thus, adding to the robustness of the standard model conclusion that Ω b ∼ 0.06. This latter point is the deriving force behind the need for non-baryonic dark matter (assuming Ω total = 1) and the need for dark baryonic matter, since Ω visible b . Recent accelerator constraints on non-baryonic matter are discussed, showing that any massive cold dark matter candidate must now have a mass M x approx-gt 20 GeV and an interaction weaker than the Z 0 coupling to a neutrino. It is also noted that recent hints regarding the solar neutrino experiments coupled with the see-saw model for ν-masses may imply that the ν τ is a good hot dark matter candidate. 73 refs., 5 figs
Asymmetric dark matter annihilation as a test of non-standard cosmologies
International Nuclear Information System (INIS)
Gelmini, Graciela B.; Huh, Ji-Haeng; Rehagen, Thomas
2013-01-01
We show that the relic abundance of the minority component of asymmetric dark matter can be very sensitive to the expansion rate of the Universe and the temperature of transition between a non-standard pre-Big Bang Nucleosynthesis cosmological phase and the standard radiation dominated phase, if chemical decoupling happens before this transition. In particular, because the annihilation cross section of asymmetric dark matter is typically larger than that of symmetric dark matter in the standard cosmology, the decrease in relic density of the minority component in non-standard cosmologies with respect to the majority component may be compensated by the increase in annihilation cross section, so that the annihilation rate at present of asymmetric dark matter, contrary to general belief, could be larger than that of symmetric dark matter in the standard cosmology. Thus, if the annihilation cross section of the asymmetric dark matter candidate is known, the annihilation rate at present, if detectable, could be used to test the Universe before Big Bang Nucleosynthesis, an epoch from which we do not yet have any data
KiDS-450: testing extensions to the standard cosmological model
Joudaki, Shahab; Mead, Alexander; Blake, Chris; Choi, Ami; de Jong, Jelte; Erben, Thomas; Fenech Conti, Ian; Herbonnet, Ricardo; Heymans, Catherine; Hildebrandt, Hendrik; Hoekstra, Henk; Joachimi, Benjamin; Klaes, Dominik; Köhlinger, Fabian; Kuijken, Konrad; McFarland, John; Miller, Lance; Schneider, Peter; Viola, Massimo
2017-10-01
We test extensions to the standard cosmological model with weak gravitational lensing tomography using 450 deg2 of imaging data from the Kilo Degree Survey (KiDS). In these extended cosmologies, which include massive neutrinos, non-zero curvature, evolving dark energy, modified gravity and running of the scalar spectral index, we also examine the discordance between KiDS and cosmic microwave background (CMB) measurements from Planck. The discordance between the two data sets is largely unaffected by a more conservative treatment of the lensing systematics and the removal of angular scales most sensitive to non-linear physics. The only extended cosmology that simultaneously alleviates the discordance with Planck and is at least moderately favoured by the data includes evolving dark energy with a time-dependent equation of state (in the form of the w0 - wa parametrization). In this model, the respective S_8=σ _8√{Ω m/0.3} constraints agree at the 1σ level, and there is 'substantial concordance' between the KiDS and Planck data sets when accounting for the full parameter space. Moreover, the Planck constraint on the Hubble constant is wider than in Λ cold dark matter (ΛCDM) and in agreement with the Riess et al. (2016) direct measurement of H0. The dark energy model is moderately favoured as compared to ΛCDM when combining the KiDS and Planck measurements, and marginalized constraints in the w0-wa plane are discrepant with a cosmological constant at the 3σ level. KiDS further constrains the sum of neutrino masses to 4.0 eV (95% CL), finds no preference for time or scale-dependent modifications to the metric potentials, and is consistent with flatness and no running of the spectral index.
Beyond the Standard Model of Cosmology
International Nuclear Information System (INIS)
Ellis, John; Nanopoulos, D. V.
2004-01-01
Recent cosmological observations of unprecented accuracy, by WMAP in particular, have established a 'Standard Model' of cosmology, just as LEP established the Standard Model of particle physics. Both Standard Models raise open questions whose answers are likely to be linked. The most fundamental problems in both particle physics and cosmology will be resolved only within a framework for Quantum Gravity, for which the only game in town is string theory. We discuss novel ways to model cosmological inflation and late acceleration in a non-critical string approach, and discuss possible astrophysical tests
Cosmological tests of modified gravity.
Koyama, Kazuya
2016-04-01
We review recent progress in the construction of modified gravity models as alternatives to dark energy as well as the development of cosmological tests of gravity. Einstein's theory of general relativity (GR) has been tested accurately within the local universe i.e. the Solar System, but this leaves the possibility open that it is not a good description of gravity at the largest scales in the Universe. This being said, the standard model of cosmology assumes GR on all scales. In 1998, astronomers made the surprising discovery that the expansion of the Universe is accelerating, not slowing down. This late-time acceleration of the Universe has become the most challenging problem in theoretical physics. Within the framework of GR, the acceleration would originate from an unknown dark energy. Alternatively, it could be that there is no dark energy and GR itself is in error on cosmological scales. In this review, we first give an overview of recent developments in modified gravity theories including f(R) gravity, braneworld gravity, Horndeski theory and massive/bigravity theory. We then focus on common properties these models share, such as screening mechanisms they use to evade the stringent Solar System tests. Once armed with a theoretical knowledge of modified gravity models, we move on to discuss how we can test modifications of gravity on cosmological scales. We present tests of gravity using linear cosmological perturbations and review the latest constraints on deviations from the standard [Formula: see text]CDM model. Since screening mechanisms leave distinct signatures in the non-linear structure formation, we also review novel astrophysical tests of gravity using clusters, dwarf galaxies and stars. The last decade has seen a number of new constraints placed on gravity from astrophysical to cosmological scales. Thanks to on-going and future surveys, cosmological tests of gravity will enjoy another, possibly even more, exciting ten years.
CERN. Geneva
2017-01-01
Extensions of Einstein’s theory of General Relativity are under investigation as a potential explanation of the accelerating expansion rate of the universe. I’ll present a cosmologist’s overview of attempts to test these ideas in an efficient and unbiased manner. I’ll start by introducing the bestiary of alternative gravity theories that have been put forwards. This proliferation of models motivates us to develop model-independent, agnostic tools for comparing the theory space to cosmological data. I’ll introduce the effective field theory for cosmological perturbations, a framework designed to unify modified gravity theories in terms of a manageable set of parameters. Having outlined the formalism, I’ll talk about the current constraints on this framework, and the improvements expected from the next generation of large galaxy clustering, weak lensing and intensity mapping experiments.
Testing cosmology with galaxy clusters
DEFF Research Database (Denmark)
Rapetti Serra, David Angelo
2011-01-01
PASCOS 2011 will be held in Cambridge UK. The conference will be hosted by the Centre for Theoretical Cosmology (DAMTP) at the Mathematical Sciences site in the University of Cambridge. The aim of the conference is to explore and develop synergies between particle physics, string theory and cosmo......PASCOS 2011 will be held in Cambridge UK. The conference will be hosted by the Centre for Theoretical Cosmology (DAMTP) at the Mathematical Sciences site in the University of Cambridge. The aim of the conference is to explore and develop synergies between particle physics, string theory...... and cosmology. There will be an emphasis on timely interdisciplinary topics: • critical tests of inflationary cosmology • advances in fundamental cosmology • applications of string theory (AdS/CMT) • particle and string phenomenology • new experimental particle physics results • and cosmological probes...
Quasars as Cosmological Standard Candles
International Nuclear Information System (INIS)
Negrete, C. Alenka; Dultzin, Deborah; Marziani, Paola; Sulentic, Jack W.; Esparza-Arredondo, Donají; Martínez-Aldama, Mary L.; Del Olmo, Ascensión
2017-01-01
We propose the use of quasars with accretion rate near the Eddington ratio (extreme quasars) as standard candles. The selection criteria are based on the Eigenvector 1 (E1) formalism. Our first sample is a selection of 334 optical quasar spectra from the SDSS DR7 database with a S/N > 20. Using the E1, we define primary and secondary selection criteria in the optical spectral range. We show that it is possible to derive a redshift-independent estimate of luminosity for extreme Eddington ratio sources. Our results are consistent with concordance cosmology but we need to work with other spectral ranges to take into account the quasar orientation, among other constrains.
Quasars as Cosmological Standard Candles
Energy Technology Data Exchange (ETDEWEB)
Negrete, C. Alenka [CONACYT Research Fellow - Instituto de Astronomía, UNAM, Mexico City (Mexico); Dultzin, Deborah [Instituto de Astronomía, UNAM, Mexico City (Mexico); Marziani, Paola [INAF, Osservatorio Astronomico di Padova, Padua (Italy); Sulentic, Jack W. [Instituto de Astrofísica de Andalucía, IAA-CSIC, Granada (Spain); Esparza-Arredondo, Donají [Instituto de Radioastronomía y Astrofísica, Morelia (Mexico); Martínez-Aldama, Mary L.; Del Olmo, Ascensión, E-mail: alenka@astro.unam.mx [Instituto de Astrofísica de Andalucía, IAA-CSIC, Granada (Spain)
2017-12-15
We propose the use of quasars with accretion rate near the Eddington ratio (extreme quasars) as standard candles. The selection criteria are based on the Eigenvector 1 (E1) formalism. Our first sample is a selection of 334 optical quasar spectra from the SDSS DR7 database with a S/N > 20. Using the E1, we define primary and secondary selection criteria in the optical spectral range. We show that it is possible to derive a redshift-independent estimate of luminosity for extreme Eddington ratio sources. Our results are consistent with concordance cosmology but we need to work with other spectral ranges to take into account the quasar orientation, among other constrains.
Superheavy magnetic monopoles and the standard cosmology
International Nuclear Information System (INIS)
Turner, M.S.
1984-10-01
The superheavy magnetic monopoles predicted to exist in grand unified theories (GUTs) are very interesting obsects, both from the point of view of particle physics, as well as from astrophysics and cosmology. Astrophysical and cosmological considerations have proved to be invaluable in studying the properties of GUT monopoles. Because of the glut of monopoles predicted in the standard cosmology for the simplest GUTs (so many that the Universe should have reached a temperature of 3 0 K at the tender age of approx. = 10,000 yrs), the simplest GUTs and the standard cosmology are not compatible. This is a very important piece of information about physics at unification energies (E greater than or equal to 10 14 GeV) and about the earliest moments (t less than or equal to 10 -34 s) of the Universe. In this talk the author reviews the cosmological consequences of GUT monopoles within the context of the standard hot big bang model. 46 references
Inflation in the standard cosmological model
Uzan, Jean-Philippe
2015-12-01
The inflationary paradigm is now part of the standard cosmological model as a description of its primordial phase. While its original motivation was to solve the standard problems of the hot big bang model, it was soon understood that it offers a natural theory for the origin of the large-scale structure of the universe. Most models rely on a slow-rolling scalar field and enjoy very generic predictions. Besides, all the matter of the universe is produced by the decay of the inflaton field at the end of inflation during a phase of reheating. These predictions can be (and are) tested from their imprint of the large-scale structure and in particular the cosmic microwave background. Inflation stands as a window in physics where both general relativity and quantum field theory are at work and which can be observationally studied. It connects cosmology with high-energy physics. Today most models are constructed within extensions of the standard model, such as supersymmetry or string theory. Inflation also disrupts our vision of the universe, in particular with the ideas of chaotic inflation and eternal inflation that tend to promote the image of a very inhomogeneous universe with fractal structure on a large scale. This idea is also at the heart of further speculations, such as the multiverse. This introduction summarizes the connections between inflation and the hot big bang model and details the basics of its dynamics and predictions. xml:lang="fr"
Improved standard cosmology: Comparison with observation
International Nuclear Information System (INIS)
Wesson, P.S.
1982-01-01
A cosmological model describing inhomogeneous clusters of galaxies embedded in a homogeneous background is compared to observation. In this model, a cluster is described as a spherically symmetric distribution of matter with an inverse-square density law and an isothermal equation of state, while the background universe is essentially the Einstein/de Sitter one of standard cosmology, but with a small pressure. The model is found to be in overall good agreement with observation, and its adjustable parameters are assigned numerical values. The equation of state for a cluster and the finite cosmological pressure are properties of the model which can in principle be investigated by carrying out observations. Subject headings: cosmology: galaxies: clusters of: relativity
Crucial test of the Dirac cosmologies
International Nuclear Information System (INIS)
Steigman, G.
1978-01-01
In a cosmology consistent with the Cosmological Principle (large scale, statistical isotropy and homogeneity of the universe), a Planck spectrum is not preserved as the universe evolves unless the number of photons in a comoving volume is conserved. It is shown that a large class of cosmological models based on Dirac's Large Numbers Hypothesis (LNH) violate this constraint. The observed isotropy and spectral distribution of the microwave background radiation thus provide a crucial test of such cosmologies. After reviewing the LNH, the general evolution of radiation spectra in cosmologies consistent with the cosmological principle is outlined. It is shown that the predicted deviations from a Planck spectrum for Dirac cosmologies (as well as for ''tired-light'' cosmologies) are enormous. The Planckian (or near-Planckian) spectral form for the microwave radiation provides a crucial test, failed by such cosmologies
Particle physics and the standard cosmology
International Nuclear Information System (INIS)
Sarkar, S.
1985-12-01
The author reviews the constraints imposed by the standard cosmological model on physics beyond the standard SU(3)sub(C) x SU(2)sub(L) x U(1)sub(Y) model, with particular attention to supersymmetry and supergravity. (author)
Cosmological tests of general relativity
International Nuclear Information System (INIS)
Hut, P.
1977-01-01
It is stated that the general relativity theory could be tested on a cosmological scale by measuring the Hubble constant and the deceleration parameter, if, in addition, everything could be known about the matter filling the universe. If, on the other hand, nothing could be presupposed about the matter content of the universe general relativity could not be tested by measuring any number of time derivatives of the scale factor. But upon making the assumption of a universe filled with non-interacting mixture of non-relativistic matter and radiation general relativity can in principle be tested by measuring the first five derivatives of the scale factor. Some general relations are here presented using this assumption. (author)
Directory of Open Access Journals (Sweden)
Crothers S. J.
2005-10-01
Full Text Available Relativistic motion in the gravitational field of a massive body is governed by the external metric of a spherically symmetric extended object. Consequently, any solution for the point-mass is inadequate for the treatment of such motions since it pertains to a fictitious object. I therefore develop herein the physics of the standard tests of General Relativity by means of the generalised solution for the field external to a sphere of incompressible homogeneous fluid.
Cosmological tests of coupled Galileons
International Nuclear Information System (INIS)
Brax, Philippe; Burrage, Clare; Davis, Anne-Christine; Gubitosi, Giulia
2015-01-01
We investigate the cosmological properties of Galileon models which admit Minkowski space as a stable solution in vacuum. This is motivated by stable, positive tension brane world constructions that give rise to Galileons. We include both conformal and disformal couplings to matter and focus on constraints on the theory that arise because of these couplings. The disformal coupling to baryonic matter is extremely constrained by astrophysical and particle physics effects. The disformal coupling to photons induces a cosmological variation of the speed of light and therefore distorsions of the Cosmic Microwave Background spectrum which are known to be very small. The conformal coupling to baryons leads to a variation of particle masses since Big Bang Nucleosynthesis which is also tightly constrained. We consider the background cosmology of Galileon models coupled to Cold Dark Matter (CDM), photons and baryons and impose that the speed of light and particle masses respect the observational bounds on cosmological time scales. We find that requiring that the equation of state for the Galileon models must be close to -1 now restricts severely their parameter space and can only be achieved with a combination of the conformal and disformal couplings. This leads to large variations of particle masses and the speed of light which are not compatible with observations. As a result, we find that cosmological Galileon models are viable dark energy theories coupled to dark matter but their couplings, both disformal and conformal, to baryons and photons must be heavily suppressed making them only sensitive to CDM
Particle accelerators test cosmological theory
International Nuclear Information System (INIS)
Schramm, D.N.; Steigman, G.
1988-01-01
Over the past decade two subfields of science, cosmology and elementary-particle physics, have become married in a symbiotic relationship that has produced a number of exciting offspring. These offspring are beginning to yield insights on the creation of spacetime and matter at epochs as early as 10 to the minus 43 to 10 to the minus 35 second after the birth of the universe in the primordial explosion known as the big bang. Important clues to the nature of the big bang itself may even come from a theory currently under development, known as the ultimate theory of everything (T.E.O.). A T.E.O. would describe all the interactions among the fundamental particles in a single bold stroke. Now that cosmology ahs begun to make predictions about elementary-particle physics, it has become conceivable that those cosmological predictions could be checked with carefully controlled accelerator experiments. It has taken more than 10 years for accelerators to reach the point where they can do the appropriate experiments, but the experiments are now in fact in progress. The preliminary results confirm the predictions of cosmology. The cosmological prediction the authors have been concerned with pertains to setting limits on the number of fundamental particles of matter. It appears that there are 12 fundamental particles, as well as their corresponding antiparticles. Six of the fundamental particles are quarks. The other six are leptons. The 12 particles are grouped in three families, each family consisting of four members. Cosmology suggests there must be a finite number of families and, further limits the possible range of to small values: only three or at most four families exist. 7 figs
Cosmology tests in rare kaon decays
Directory of Open Access Journals (Sweden)
Duk Viacheslav
2016-01-01
Full Text Available The Standard Model (SM of particle physics is an extremely successful theory that effectively describes strong and electroweak interactions up to the energies presently accessible. Still, the SM does not explain the observed parameters of neutrino oscillations, baryon asymmetry of the Universe and Dark Matter (DM, and contains a fine-tuning of 16 orders of magnitude (the gauge hierarchy problem. Various New Physics (NP models beyond the SM have been developed in order to address the above limitations. This paper concentrates on several models related to cosmology and their tests in rare kaon decays. In particular, recent NA48/2 results on the search for heavy neutrinos, light in-flatons and dark photons are presented. Prospects for the ongoing NA62 experiment are discussed.
Cosmological tests of a scale covariant theory of gravitation
International Nuclear Information System (INIS)
Owen, J.R.
1979-01-01
The Friedmann models with #betta# = 0 are subjected to several optical and radio tests within the standard and scale covariant theories of gravitation. Within standard cosmology, both interferometric and scintillation data are interpreted in terms of selection effects and evolution. Within the context of scale covariant cosmology are derived: (1) the full solution to Einstein's gravitational equations in atomic units for a matter dominated universe, (2) the study of the magnitude vs. redshift relation for elliptical galaxies, (3) the derivation of the evolutionary parameter used in (2), (4) the isophotal angular diameter vs. redshift relation, (5) the metric angular diameter vs. redshift relation, (6) the N(m) vs. magnitude relation for QSO's and their m vs z relation, and finally (7) the integrated and differential expressions for the number count vs. radio flux test. The results, both in graphical and tabular form, are presented for four gauges (i.e. parametrized relations between atomic and gravitational units). No contradiction between the new theory and the data is found with any of the tests studied. For some gauges, which are suggested by a recent analysis of the time variation of the Moon's period which is discussed in the text in terms of the new theory, the effect of the deceleration parameter on cosmological predictions is enhanced over standard cosmology and it is possible to say that the data are more easily reconciled with an open universe. Within the same gauge, the main features of both the N(m) vs. m and m-z test are accounted for by the same simple evolutionary parametrization whereas different evolutionary rates were indicated by interpretation within standard cosmology. The same consistency, lacking in standard cosmology on this level of analysis, is achieved for the integrated and differential number count - radio flux tests within the same gauge
García-Bellido, J
2015-01-01
In these lectures I review the present status of the so-called Standard Cosmological Model, based on the hot Big Bang Theory and the Inflationary Paradigm. I will make special emphasis on the recent developments in observational cosmology, mainly the acceleration of the universe, the precise measurements of the microwave background anisotropies, and the formation of structure like galaxies and clusters of galaxies from tiny primordial fluctuations generated during inflation.
Testing the equivalence principle on cosmological scales
Bonvin, Camille; Fleury, Pierre
2018-05-01
The equivalence principle, that is one of the main pillars of general relativity, is very well tested in the Solar system; however, its validity is more uncertain on cosmological scales, or when dark matter is concerned. This article shows that relativistic effects in the large-scale structure can be used to directly test whether dark matter satisfies Euler's equation, i.e. whether its free fall is characterised by geodesic motion, just like baryons and light. After having proposed a general parametrisation for deviations from Euler's equation, we perform Fisher-matrix forecasts for future surveys like DESI and the SKA, and show that such deviations can be constrained with a precision of order 10%. Deviations from Euler's equation cannot be tested directly with standard methods like redshift-space distortions and gravitational lensing, since these observables are not sensitive to the time component of the metric. Our analysis shows therefore that relativistic effects bring new and complementary constraints to alternative theories of gravity.
Testing typicality in multiverse cosmology
Azhar, Feraz
2015-05-01
In extracting predictions from theories that describe a multiverse, we face the difficulty that we must assess probability distributions over possible observations prescribed not just by an underlying theory, but by a theory together with a conditionalization scheme that allows for (anthropic) selection effects. This means we usually need to compare distributions that are consistent with a broad range of possible observations with actual experimental data. One controversial means of making this comparison is by invoking the "principle of mediocrity": that is, the principle that we are typical of the reference class implicit in the conjunction of the theory and the conditionalization scheme. In this paper, we quantitatively assess the principle of mediocrity in a range of cosmological settings, employing "xerographic distributions" to impose a variety of assumptions regarding typicality. We find that for a fixed theory, the assumption that we are typical gives rise to higher likelihoods for our observations. If, however, one allows both the underlying theory and the assumption of typicality to vary, then the assumption of typicality does not always provide the highest likelihoods. Interpreted from a Bayesian perspective, these results support the claim that when one has the freedom to consider different combinations of theories and xerographic distributions (or different "frameworks"), one should favor the framework that has the highest posterior probability; and then from this framework one can infer, in particular, how typical we are. In this way, the invocation of the principle of mediocrity is more questionable than has been recently claimed.
Cosmological implications of standard model extensions
Peña Jiménez, Manuel
2013-01-01
Los modelos estándar tanto de partículas como de Cosmología son capaces de describir una gran cantidad de datos experimentales con una increíble precisión. Sin embargo, en ciertas áreas de estos modelos aún existen discrepancias frente a lo descrito teóricamente y lo observado en la naturaleza. En concreto, el modelo estándar de partículas es incapaz de dar una explicación del patrón de masas y mezclas observadas en las partículas conocidas (siendo de suma importancia la m...
Vittorio, Nicola
2018-01-01
Modern cosmology has changed significantly over the years, from the discovery to the precision measurement era. The data now available provide a wealth of information, mostly consistent with a model where dark matter and dark energy are in a rough proportion of 3:7. The time is right for a fresh new textbook which captures the state-of-the art in cosmology. Written by one of the world's leading cosmologists, this brand new, thoroughly class-tested textbook provides graduate and undergraduate students with coverage of the very latest developments and experimental results in the field. Prof. Nicola Vittorio shows what is meant by precision cosmology, from both theoretical and observational perspectives.
A null test of the cosmological constant
International Nuclear Information System (INIS)
Chiba, Takeshi; Nakamura, Takashi
2007-01-01
We provide a consistency relation between cosmological observables in general relativity with the cosmological constant. Breaking of this relation at any redshift would imply the breakdown of the hypothesis of the cosmological constant as an explanation of the current acceleration of the universe. (author)
Kinematic tests of exotic flat cosmological models
International Nuclear Information System (INIS)
Charlton, J.C.; Turner, M.S.; NASA/Fermilab Astrophysics Center, Batavia, IL)
1987-01-01
Theoretical prejudice and inflationary models of the very early universe strongly favor the flat, Einstein-de Sitter model of the universe. At present the observational data conflict with this prejudice. This conflict can be resolved by considering flat models of the universe which posses a smooth component of energy density. The kinematics of such models, where the smooth component is relativistic particles, a cosmological term, a network of light strings, or fast-moving, light strings is studied in detail. The observational tests which can be used to discriminate between these models are also discussed. These tests include the magnitude-redshift, lookback time-redshift, angular size-redshift, and comoving volume-redshift diagrams and the growth of density fluctuations. 58 references
Kinematic tests of exotic flat cosmological models
International Nuclear Information System (INIS)
Charlton, J.C.; Turner, M.S.
1986-05-01
Theoretical prejudice and inflationary models of the very early Universe strongly favor the flat, Einstein-deSitter model of the Universe. At present the observational data conflict with this prejudice. This conflict can be resolved by considering flat models of the Universe which possess a smooth component by energy density. We study in detail the kinematics of such models, where the smooth component is relativistic particles, a cosmological term, a network of light strings, or fast-moving, light strings. We also discuss the observational tests which can be used to discriminate between these models. These tests include the magnitude-redshift, lookback time-redshift, angular size-redshift, and comoving volume-redshift diagrams and the growth of density fluctuations
Kinematic tests of exotic flat cosmological models
Energy Technology Data Exchange (ETDEWEB)
Charlton, J.C.; Turner, M.S.
1986-05-01
Theoretical prejudice and inflationary models of the very early Universe strongly favor the flat, Einstein-deSitter model of the Universe. At present the observational data conflict with this prejudice. This conflict can be resolved by considering flat models of the Universe which possess a smooth component by energy density. We study in detail the kinematics of such models, where the smooth component is relativistic particles, a cosmological term, a network of light strings, or fast-moving, light strings. We also discuss the observational tests which can be used to discriminate between these models. These tests include the magnitude-redshift, lookback time-redshift, angular size-redshift, and comoving volume-redshift diagrams and the growth of density fluctuations.
International Nuclear Information System (INIS)
Novikov, I.D.
1979-01-01
Progress made by this Commission over the period 1976-1978 is reviewed. Topics include the Hubble constant, deceleration parameter, large-scale distribution of matter in the universe, radio astronomy and cosmology, space astronomy and cosmology, formation of galaxies, physics near the cosmological singularity, and unconventional cosmological models. (C.F.)
CERN. Geneva
2011-01-01
While the cosmological standard model has many notable successes, it assumes 95% of the mass-energy density of the universe is dark and of unknown nature, and there was an early stage of inflationary expansion driven by physics far beyond the range of the particle physics standard model. In the colloquium I will discuss potential particle-physics implications of the standard cosmological model.
Kunze, Kerstin E.
2016-12-20
Cosmology is becoming an important tool to test particle physics models. We provide an overview of the standard model of cosmology with an emphasis on the observations relevant for testing fundamental physics.
A Monte Carlo Simulation Framework for Testing Cosmological Models
Directory of Open Access Journals (Sweden)
Heymann Y.
2014-10-01
Full Text Available We tested alternative cosmologies using Monte Carlo simulations based on the sam- pling method of the zCosmos galactic survey. The survey encompasses a collection of observable galaxies with respective redshifts that have been obtained for a given spec- troscopic area of the sky. Using a cosmological model, we can convert the redshifts into light-travel times and, by slicing the survey into small redshift buckets, compute a curve of galactic density over time. Because foreground galaxies obstruct the images of more distant galaxies, we simulated the theoretical galactic density curve using an average galactic radius. By comparing the galactic density curves of the simulations with that of the survey, we could assess the cosmologies. We applied the test to the expanding-universe cosmology of de Sitter and to a dichotomous cosmology.
Relic abundance of WIMPs in non-standard cosmological scenarios
International Nuclear Information System (INIS)
Yimingniyazi, W.
2007-01-01
In this thesis we study the relic density n χ of non--relativistic long--lived or stable particles χ in various non--standard cosmological scenarios. First, we discuss the relic density in the non--standard cosmological scenario in which the temperature is too low for the particles χ to achieve full chemical equilibrium. We also investigated the case where χ particles are non--thermally produced from the decay of heavier particles in addition to the usual thermal production. In low temperature scenario, we calculate the relic abundance starting from arbitrary initial temperatures T 0 of the radiation--dominated epoch and derive approximate solutions for the temperature dependence of the relic density which can accurately reproduces numerical results when full thermal equilibrium is not achieved. If full equilibrium is reached, our ansatz no longer reproduces the correct temperature dependence of the χ number density. However, we can contrive a semi-analytic formula which gives the correct final relic density, to an accuracy of about 3% or better, for all cross sections and initial temperatures. We also derive the lower bound on the initial temperature T 0 , assuming that the relic particle accounts for the dark matter energy density in the universe. The observed cold dark matter abundance constrains the initial temperature T 0 ≥m χ /23, where m χ is the mass of χ. Second, we discuss the χ density in the scenario where the the Hubble parameter is modified. Even in this case, an approximate formula similar to the standard one is found to be capable of predicting the final relic abundance correctly. Choosing the χ annihilation cross section such that the observed cold dark matter abundance is reproduced in standard cosmology, we constrain possible modifications of the expansion rate at T ∝m χ /20, well before Big Bang Nucleosynthesis. (orig.)
Relic abundance of WIMPs in non-standard cosmological scenarios
Energy Technology Data Exchange (ETDEWEB)
Yimingniyazi, W.
2007-08-06
In this thesis we study the relic density n{sub {chi}} of non--relativistic long--lived or stable particles {chi} in various non--standard cosmological scenarios. First, we discuss the relic density in the non--standard cosmological scenario in which the temperature is too low for the particles {chi} to achieve full chemical equilibrium. We also investigated the case where {chi} particles are non--thermally produced from the decay of heavier particles in addition to the usual thermal production. In low temperature scenario, we calculate the relic abundance starting from arbitrary initial temperatures T{sub 0} of the radiation--dominated epoch and derive approximate solutions for the temperature dependence of the relic density which can accurately reproduces numerical results when full thermal equilibrium is not achieved. If full equilibrium is reached, our ansatz no longer reproduces the correct temperature dependence of the {chi} number density. However, we can contrive a semi-analytic formula which gives the correct final relic density, to an accuracy of about 3% or better, for all cross sections and initial temperatures. We also derive the lower bound on the initial temperature T{sub 0}, assuming that the relic particle accounts for the dark matter energy density in the universe. The observed cold dark matter abundance constrains the initial temperature T{sub 0} {>=}m{sub {chi}}/23, where m{sub {chi}} is the mass of {chi}. Second, we discuss the {chi} density in the scenario where the the Hubble parameter is modified. Even in this case, an approximate formula similar to the standard one is found to be capable of predicting the final relic abundance correctly. Choosing the {chi} annihilation cross section such that the observed cold dark matter abundance is reproduced in standard cosmology, we constrain possible modifications of the expansion rate at T {proportional_to}m{sub {chi}}/20, well before Big Bang Nucleosynthesis. (orig.)
International Nuclear Information System (INIS)
Contopoulos, G.; Kotsakis, D.
1987-01-01
An extensive first part on a wealth of observational results relevant to cosmology lays the foundation for the second and central part of the book; the chapters on general relativity, the various cosmological theories, and the early universe. The authors present in a complete and almost non-mathematical way the ideas and theoretical concepts of modern cosmology including the exciting impact of high-energy particle physics, e.g. in the concept of the ''inflationary universe''. The final part addresses the deeper implications of cosmology, the arrow of time, the universality of physical laws, inflation and causality, and the anthropic principle
Cosmological consistency tests of gravity theory and cosmic acceleration
Ishak-Boushaki, Mustapha B.
2017-01-01
Testing general relativity at cosmological scales and probing the cause of cosmic acceleration are among the important objectives targeted by incoming and future astronomical surveys and experiments. I present our recent results on consistency tests that can provide insights about the underlying gravity theory and cosmic acceleration using cosmological data sets. We use statistical measures, the rate of cosmic expansion, the growth rate of large scale structure, and the physical consistency of these probes with one another.
Testing averaged cosmology with type Ia supernovae and BAO data
Energy Technology Data Exchange (ETDEWEB)
Santos, B.; Alcaniz, J.S. [Departamento de Astronomia, Observatório Nacional, 20921-400, Rio de Janeiro – RJ (Brazil); Coley, A.A. [Department of Mathematics and Statistics, Dalhousie University, Halifax, B3H 3J5 Canada (Canada); Devi, N. Chandrachani, E-mail: thoven@on.br, E-mail: aac@mathstat.dal.ca, E-mail: chandrachaniningombam@astro.unam.mx, E-mail: alcaniz@on.br [Instituto de Astronomía, Universidad Nacional Autónoma de México, Box 70-264, México City, México (Mexico)
2017-02-01
An important problem in precision cosmology is the determination of the effects of averaging and backreaction on observational predictions, particularly in view of the wealth of new observational data and improved statistical techniques. In this paper, we discuss the observational viability of a class of averaged cosmologies which consist of a simple parametrized phenomenological two-scale backreaction model with decoupled spatial curvature parameters. We perform a Bayesian model selection analysis and find that this class of averaged phenomenological cosmological models is favored with respect to the standard ΛCDM cosmological scenario when a joint analysis of current SNe Ia and BAO data is performed. In particular, the analysis provides observational evidence for non-trivial spatial curvature.
Testing averaged cosmology with type Ia supernovae and BAO data
International Nuclear Information System (INIS)
Santos, B.; Alcaniz, J.S.; Coley, A.A.; Devi, N. Chandrachani
2017-01-01
An important problem in precision cosmology is the determination of the effects of averaging and backreaction on observational predictions, particularly in view of the wealth of new observational data and improved statistical techniques. In this paper, we discuss the observational viability of a class of averaged cosmologies which consist of a simple parametrized phenomenological two-scale backreaction model with decoupled spatial curvature parameters. We perform a Bayesian model selection analysis and find that this class of averaged phenomenological cosmological models is favored with respect to the standard ΛCDM cosmological scenario when a joint analysis of current SNe Ia and BAO data is performed. In particular, the analysis provides observational evidence for non-trivial spatial curvature.
No Evidence for Extensions to the Standard Cosmological Model
Heavens, Alan; Fantaye, Yabebal; Sellentin, Elena; Eggers, Hans; Hosenie, Zafiirah; Kroon, Steve; Mootoovaloo, Arrykrishna
2017-09-01
We compute the Bayesian evidence for models considered in the main analysis of Planck cosmic microwave background data. By utilizing carefully defined nearest-neighbor distances in parameter space, we reuse the Monte Carlo Markov chains already produced for parameter inference to compute Bayes factors B for many different model-data set combinations. The standard 6-parameter flat cold dark matter model with a cosmological constant (Λ CDM ) is favored over all other models considered, with curvature being mildly favored only when cosmic microwave background lensing is not included. Many alternative models are strongly disfavored by the data, including primordial correlated isocurvature models (ln B =-7.8 ), nonzero scalar-to-tensor ratio (ln B =-4.3 ), running of the spectral index (ln B =-4.7 ), curvature (ln B =-3.6 ), nonstandard numbers of neutrinos (ln B =-3.1 ), nonstandard neutrino masses (ln B =-3.2 ), nonstandard lensing potential (ln B =-4.6 ), evolving dark energy (ln B =-3.2 ), sterile neutrinos (ln B =-6.9 ), and extra sterile neutrinos with a nonzero scalar-to-tensor ratio (ln B =-10.8 ). Other models are less strongly disfavored with respect to flat Λ CDM . As with all analyses based on Bayesian evidence, the final numbers depend on the widths of the parameter priors. We adopt the priors used in the Planck analysis, while performing a prior sensitivity analysis. Our quantitative conclusion is that extensions beyond the standard cosmological model are disfavored by Planck data. Only when newer Hubble constant measurements are included does Λ CDM become disfavored, and only mildly, compared with a dynamical dark energy model (ln B ˜+2 ).
Standard cosmological evolution in the f(R) model to Kaluza-Klein cosmology
International Nuclear Information System (INIS)
Aghmohammadi, A; Abolhassani, M R; Saaidi, Kh; Vajdi, A
2009-01-01
In this paper, using f(R) theory of gravity we explicitly calculate cosmological evolution in the presence of a perfect fluid source in four- and five-dimensional space-time in which this cosmological evolution in self-creation is presented by Reddy et al (2009 Int. J. Theor. Phys. 48 10). An exact cosmological model is presented using a relation between Einstein's gravity field equation components due to a metric with the same component from f(R) theory of gravity. Some physics and kinematical properties of the model are also discussed.
Testing and selecting cosmological models with ultra-compact radio quasars
Energy Technology Data Exchange (ETDEWEB)
Li, Xiaolei [Beijing Normal University, Department of Astronomy, Beijing (China); University of Michigan, Department of Physics, Ann Arbor, MI (United States); Cao, Shuo; Qi, Jingzhao; Zhu, Zong-Hong [Beijing Normal University, Department of Astronomy, Beijing (China); Zheng, Xiaogang; Biesiada, Marek [Beijing Normal University, Department of Astronomy, Beijing (China); University of Silesia, Department of Astrophysics and Cosmology, Institute of Phyisics, Katowice (Poland)
2017-10-15
In this paper, we place constraints on four alternative cosmological models under the assumption of the spatial flatness of the Universe: CPL, EDE, GCG and MPC. A new compilation of 120 compact radio quasars observed by very-long-baseline interferometry, which represents a type of new cosmological standard rulers, are used to test these cosmological models. Our results show that the fits on CPL obtained from the quasar sample are well consistent with those obtained from BAO. For other cosmological models considered, quasars provide constraints in agreement with those derived with other standard probes at 1σ confidence level. Moreover, the results obtained from other statistical methods including figure of merit, Om(z) and statefinder diagnostics indicate that: (1) Radio quasar standard ruler could provide better statistical constraints than BAO for all cosmological models considered, which suggests its potential to act as a powerful complementary probe to BAO and galaxy clusters. (2) Turning to Om(z) diagnostics, CPL, GCG and EDE models cannot be distinguished from each other at the present epoch. (3) In the framework of statefinder diagnostics, MPC and EDE will deviate from the ΛCDM model in the near future, while GCG model cannot be distinguished from the ΛCDM model unless much higher precision observations are available. (orig.)
Introduction to particle cosmology the standard model of cosmology and its open problems
Bambi, Cosimo
2016-01-01
This book introduces the basic concepts of particle cosmology and covers all the main aspects of the Big Bang Model (expansion of the Universe, Big Bang Nucleosynthesis, Cosmic Microwave Background, large scale structures) and the search for new physics (inflation, baryogenesis, dark matter, dark energy). It also includes the majority of recent discoveries, such as the precise determination of cosmological parameters using experiments like WMAP and Planck, the discovery of the Higgs boson at LHC, the non-discovery to date of supersymmetric particles, and the search for the imprint of gravitational waves on the CMB polarization by Planck and BICEP. This textbook is based on the authors’ courses on Cosmology, and aims at introducing Particle Cosmology to senior undergraduate and graduate students. It has been especially written to be accessible even for those students who do not have a strong background in General Relativity and quantum field theory. The content of this book is organized in an easy-to-use ...
A new golden age: testing general relativity with cosmology.
Bean, Rachel; Ferreira, Pedro G; Taylor, Andy
2011-12-28
Gravity drives the evolution of the Universe and is at the heart of its complexity. Einstein's field equations can be used to work out the detailed dynamics of space and time and to calculate the emergence of large-scale structure in the distribution of galaxies and radiation. Over the past few years, it has become clear that cosmological observations can be used not only to constrain different world models within the context of Einstein gravity but also to constrain the theory of gravity itself. In this article, we look at different aspects of this new field in which cosmology is used to test theories of gravity with a wide range of observations.
Early universe cosmology and tests of fundamental physics
International Nuclear Information System (INIS)
Albrecht, Andreas; Frieman, Joshua A.; Trodden, Mark
2002-01-01
This is the report of the Working Group on Early Universe Cosmology and tests of Fundamental Physics, group P4.8 of the of the Snowmass 2001 conference. Here we summarize the impressive array of advances that have taken place in this field, and identify opportunities for even greater progress in the future. Topics include Dark Energy, Cosmic Acceleration, Inflation, Phase Transitions, Baryogenesis, and String/M-theory Cosmology. The introductory section gives an executive summary with six key open questions on which we can expect to make significant progress
Early universe cosmology. In supersymmetric extensions of the standard model
Energy Technology Data Exchange (ETDEWEB)
Baumann, Jochen Peter
2012-03-19
In this thesis we investigate possible connections between cosmological inflation and leptogenesis on the one side and particle physics on the other side. We work in supersymmetric extensions of the Standard Model. A key role is played by the right-handed sneutrino, the superpartner of the right-handed neutrino involved in the type I seesaw mechanism. We study a combined model of inflation and non-thermal leptogenesis that is a simple extension of the Minimal Supersymmetric Standard Model (MSSM) with conserved R-parity, where we add three right-handed neutrino super fields. The inflaton direction is given by the imaginary components of the corresponding scalar component fields, which are protected from the supergravity (SUGRA) {eta}-problem by a shift symmetry in the Kaehler potential. We discuss the model first in a globally supersymmetric (SUSY) and then in a supergravity context and compute the inflationary predictions of the model. We also study reheating and non-thermal leptogenesis in this model. A numerical simulation shows that shortly after the waterfall phase transition that ends inflation, the universe is dominated by right-handed sneutrinos and their out-of-equilibrium decay can produce the desired matter-antimatter asymmetry. Using a simplified time-averaged description, we derive analytical expressions for the model predictions. Combining the results from inflation and leptogenesis allows us to constrain the allowed parameter space from two different directions, with implications for low energy neutrino physics. As a second thread of investigation, we discuss a generalisation of the inflationary model discussed above to include gauge non-singlet fields as inflatons. This is motivated by the fact that in left-right symmetric, supersymmetric Grand Unified Theories (SUSY GUTs), like SUSY Pati-Salam unification or SUSY SO(10) GUTs, the righthanded (s)neutrino is an indispensable ingredient and does not have to be put in by hand as in the MSSM. We discuss
Early universe cosmology. In supersymmetric extensions of the standard model
International Nuclear Information System (INIS)
Baumann, Jochen Peter
2012-01-01
In this thesis we investigate possible connections between cosmological inflation and leptogenesis on the one side and particle physics on the other side. We work in supersymmetric extensions of the Standard Model. A key role is played by the right-handed sneutrino, the superpartner of the right-handed neutrino involved in the type I seesaw mechanism. We study a combined model of inflation and non-thermal leptogenesis that is a simple extension of the Minimal Supersymmetric Standard Model (MSSM) with conserved R-parity, where we add three right-handed neutrino super fields. The inflaton direction is given by the imaginary components of the corresponding scalar component fields, which are protected from the supergravity (SUGRA) η-problem by a shift symmetry in the Kaehler potential. We discuss the model first in a globally supersymmetric (SUSY) and then in a supergravity context and compute the inflationary predictions of the model. We also study reheating and non-thermal leptogenesis in this model. A numerical simulation shows that shortly after the waterfall phase transition that ends inflation, the universe is dominated by right-handed sneutrinos and their out-of-equilibrium decay can produce the desired matter-antimatter asymmetry. Using a simplified time-averaged description, we derive analytical expressions for the model predictions. Combining the results from inflation and leptogenesis allows us to constrain the allowed parameter space from two different directions, with implications for low energy neutrino physics. As a second thread of investigation, we discuss a generalisation of the inflationary model discussed above to include gauge non-singlet fields as inflatons. This is motivated by the fact that in left-right symmetric, supersymmetric Grand Unified Theories (SUSY GUTs), like SUSY Pati-Salam unification or SUSY SO(10) GUTs, the righthanded (s)neutrino is an indispensable ingredient and does not have to be put in by hand as in the MSSM. We discuss the
International Nuclear Information System (INIS)
Gonzalez-Mestres, Luis
2016-01-01
A year ago, we wrote [1] that the field of Cosmology was undergoing a positive and constructive crisis. The possible development of more direct links between the Mathematical Physics aspects of cosmological patterns and the interpretation of experimental and observational results was particularly emphasized. Controversies on inflation are not really new, but in any case inflation is not required in pre-Big Bang models and the validity of the standard Big Bang + inflation + ΛCDM pattern has not by now been demonstrated by data. Planck has even explicitly reported the existence of “anomalies”. Remembering the far-reaching work of Yoichiro Nambu published in 1959-61, it seems legitimate to underline the need for a cross-disciplinary approach in the presence of deep, unsolved theoretical problems concerning new domains of matter properties and of the physical world. The physics of a possible preonic vacuum and the associated cosmology constitute one of these domains. If the vacuum is made of superluminal preons (superbradyons), and if standard particles are vacuum excitations, how to build a suitable theory to describe the internal structure of such a vacuum at both local and cosmic level? Experimental programs (South Pole, Atacama, AUGER, Telescope Array…) and observational ones (Planck, JEM-EUSO…) devoted to the study of cosmic microwave background radiation (CMB) and of ultra-high energy cosmic rays (UHECR) are crucial to elucidate such theoretical interrogations and guide new phenomenological developments. Together with a brief review of the observational and experimental situation, we also examine the main present theoretical and phenomenological problems and point out the role new physics and alternative cosmologies can potentially play. The need for data analyses less focused a priori on the standard models of Particle Physics and Cosmology is emphasized in this discussion. An example of a new approach to both fields is provided by the pre-Big Bang
Gonzalez-Mestres, Luis
2016-11-01
A year ago, we wrote [1] that the field of Cosmology was undergoing a positive and constructive crisis. The possible development of more direct links between the Mathematical Physics aspects of cosmological patterns and the interpretation of experimental and observational results was particularly emphasized. Controversies on inflation are not really new, but in any case inflation is not required in pre-Big Bang models and the validity of the standard Big Bang + inflation + ΛCDM pattern has not by now been demonstrated by data. Planck has even explicitly reported the existence of "anomalies". Remembering the far-reaching work of Yoichiro Nambu published in 1959-61, it seems legitimate to underline the need for a cross-disciplinary approach in the presence of deep, unsolved theoretical problems concerning new domains of matter properties and of the physical world. The physics of a possible preonic vacuum and the associated cosmology constitute one of these domains. If the vacuum is made of superluminal preons (superbradyons), and if standard particles are vacuum excitations, how to build a suitable theory to describe the internal structure of such a vacuum at both local and cosmic level? Experimental programs (South Pole, Atacama, AUGER, Telescope Array…) and observational ones (Planck, JEM-EUSO…) devoted to the study of cosmic microwave background radiation (CMB) and of ultra-high energy cosmic rays (UHECR) are crucial to elucidate such theoretical interrogations and guide new phenomenological developments. Together with a brief review of the observational and experimental situation, we also examine the main present theoretical and phenomenological problems and point out the role new physics and alternative cosmologies can potentially play. The need for data analyses less focused a priori on the standard models of Particle Physics and Cosmology is emphasized in this discussion. An example of a new approach to both fields is provided by the pre-Big Bang pattern
Testing the cosmological constant as a candidate for dark energy
International Nuclear Information System (INIS)
Kratochvil, Jan; Linde, Andrei; Linder, Eric V.; Shmakova, Marina
2004-01-01
It may be difficult to single out the best model of dark energy on the basis of the existing and planned cosmological observations, because many different models can lead to similar observational consequences. However, each particular model can be studied and either found consistent with observations or ruled out. In this paper, we concentrate on the possibility to test and rule out the simplest and by far the most popular of the models of dark energy, the theory described by general relativity with positive vacuum energy (the cosmological constant). We evaluate the conditions under which this model could be ruled out by the future observations made by the Supernova/Acceleration Probe SNAP (both for supernovae and weak lensing) and by the Planck Surveyor cosmic microwave background satellite
Tests of the particle physics-physical cosmology interface
International Nuclear Information System (INIS)
Schramm, D.N.
1993-01-01
Three interrelated interfaces of particle physics and physical cosmology are discussed: (1) inflation and other phase transitions; (2) Big Bang Nucleosynthesis (and also the quark-hadron transition); and (3) structure formation (including dark matter). Recent observations that affect each of these topics are discussed. Topic number 1 is shown to be consistent with the COBE observations but not proven and it may be having problems with some age-expansion data. Topic number 2 has now been well-tested and is an established ''pillar'' of the Big Bang. Topic number 3 is the prime arena of current physical cosmological activity. Experiments to resolve the current exciting, but still ambiguous, situation following the COBE results are discussed
Cosmological tests on Visser's massive graviton dark matter cosmology
Energy Technology Data Exchange (ETDEWEB)
Hu, Xin-Yun; Liu, Xian-Ming [Hubei University for Nationalities, Department of Physics, Enshi, Hubei (China); Zeng, Xiao-Xiong [Chongqing Jiaotong University, School of Science, Nanan (China)
2013-06-15
We present the constraints on the Massive Graviton Dark Matter scenario (MGCDM) using the cosmological observations, including type Ia supernovae (SNe Ia), Gamma Ray Bursts (GRB), Observational Hubble Parameter Data (OHD), Cosmic Microwave Background shift parameter, and the Radial Baryon Acoustic Oscillation. In order to compare the goodness of the data samples and their combinations, we adopt the Fisher matrix analysis and the figure of merit (FoM) diagnostic. Based on the constraint results, we further discuss the cosmic age problem in MGCDM. The calculation shows that the universe in MGCDM frame is older than that in standard {Lambda}CDM model, but the cosmic age crisis is still unresolved with just an alleviation. (orig.)
Testing general relativity at cosmological scales: Implementation and parameter correlations
International Nuclear Information System (INIS)
Dossett, Jason N.; Ishak, Mustapha; Moldenhauer, Jacob
2011-01-01
The testing of general relativity at cosmological scales has become a possible and timely endeavor that is not only motivated by the pressing question of cosmic acceleration but also by the proposals of some extensions to general relativity that would manifest themselves at large scales of distance. We analyze here correlations between modified gravity growth parameters and some core cosmological parameters using the latest cosmological data sets including the refined Cosmic Evolution Survey 3D weak lensing. We provide the parametrized modified growth equations and their evolution. We implement known functional and binning approaches, and propose a new hybrid approach to evolve the modified gravity parameters in redshift (time) and scale. The hybrid parametrization combines a binned redshift dependence and a smooth evolution in scale avoiding a jump in the matter power spectrum. The formalism developed to test the consistency of current and future data with general relativity is implemented in a package that we make publicly available and call ISiTGR (Integrated Software in Testing General Relativity), an integrated set of modified modules for the publicly available packages CosmoMC and CAMB, including a modified version of the integrated Sachs-Wolfe-galaxy cross correlation module of Ho et al. and a new weak-lensing likelihood module for the refined Hubble Space Telescope Cosmic Evolution Survey weak gravitational lensing tomography data. We obtain parameter constraints and correlation coefficients finding that modified gravity parameters are significantly correlated with σ 8 and mildly correlated with Ω m , for all evolution methods. The degeneracies between σ 8 and modified gravity parameters are found to be substantial for the functional form and also for some specific bins in the hybrid and binned methods indicating that these degeneracies will need to be taken into consideration when using future high precision data.
Deviation from Standard Inflationary Cosmology and the Problems in Ekpyrosis
Tseng, Chien-Yao
There are two competing models of our universe right now. One is Big Bang with inflation cosmology. The other is the cyclic model with ekpyrotic phase in each cycle. This paper is divided into two main parts according to these two models. In the first part, we quantify the potentially observable effects of a small violation of translational invariance during inflation, as characterized by the presence of a preferred point, line, or plane. We explore the imprint such a violation would leave on the cosmic microwave background anisotropy, and provide explicit formulas for the expected amplitudes ( alma*l'm') of the spherical-harmonic coefficients. We then provide a model and study the two-point correlation of a massless scalar (the inflaton) when the stress tensor contains the energy density from an infinitely long straight cosmic string in addition to a cosmological constant. Finally, we discuss if inflation can reconcile with the Liouville's theorem as far as the fine-tuning problem is concerned. In the second part, we find several problems in the cyclic/ekpyrotic cosmology. First of all, quantum to classical transition would not happen during an ekpyrotic phase even for superhorizon modes, and therefore the fluctuations cannot be interpreted as classical. This implies the prediction of scale-free power spectrum in ekpyrotic/cyclic universe model requires more inspection. Secondly, we find that the usual mechanism to solve fine-tuning problems is not compatible with eternal universe which contains infinitely many cycles in both direction of time. Therefore, all fine-tuning problems including the flatness problem still asks for an explanation in any generic cyclic models.
What does cosmology tell us about particle physics beyond the Standard Model?
Komatsu, Eiichiro
2012-07-01
Cosmology demands particle physics beyond the Standard Model: we need to explain the nature of dark matter and dark energy, and the physics of cosmic inflation. Cosmology also provides the tightest upper bound on the sum of neutrino masses, and it seems only a matter of time before we measure the absolute mass of neutrinos, unveiling the neutrino mass hierarchy. It also provides a measurement of the number of relativistic species at the photon decoupling epoch (at which the temperature of the universe is 3000 K). Astronomy and Astrophysics Decadal Survey conducted by USA's National Academy of Sciences has identified these four topics (dark matter, dark energy, inflation and neutrinos) as the most important subjects to study in cosmology over the next decade. In this contribution, we review the current status on these topics, in light of the recent cosmological constraints.
Ultra-cold WIMPs relics of non-standard pre-BBN cosmologies
Gelmini, Graciela B
2008-01-01
We point out that in scenarios in which the Universe evolves in a non-standard manner during and after the kinetic decoupling of weakly interacting massive particles (WIMPs), these relics can be much colder than in standard cosmological scenarios (i.e. can be ultra-cold), possibly leading to the formation of smaller first objects in hierarchical structure formation scenarios.
Energy Technology Data Exchange (ETDEWEB)
Vilenkin, Alexander, E-mail: vilenkin@cosmos.phy.tufts.ed [Institute of Cosmology, Department of Physics and Astronomy, Tufts University, Medford, MA 02155 (United States)
2010-01-01
The 'new standard cosmology', based on the theory of inflation, has very impressive observational support. I review some outstanding problems of the new cosmology and the global view of the universe - the multiverse - that it suggests. I focus in particular on prospects for further observational tests of inflation and of the multiverse.
International Nuclear Information System (INIS)
Vilenkin, Alexander
2010-01-01
The n ew standard cosmology , based on the theory of inflation, has very impressive observational support. I review some outstanding problems of the new cosmology and the global view of the universe - the multiverse - that it suggests. I focus in particular on prospects for further observational tests of inflation and of the multiverse.
International Nuclear Information System (INIS)
Gordon, H.; Marciano, W.; Williams, H.H.
1982-01-01
We summarize here the results of the standard model group which has studied the ways in which different facilities may be used to test in detail what we now call the standard model, that is SU/sub c/(3) x SU(2) x U(1). The topics considered are: W +- , Z 0 mass, width; sin 2 theta/sub W/ and neutral current couplings; W + W - , Wγ; Higgs; QCD; toponium and naked quarks; glueballs; mixing angles; and heavy ions
From Planck Data to Planck Era: Observational Tests of Holographic Cosmology.
Afshordi, Niayesh; Corianò, Claudio; Delle Rose, Luigi; Gould, Elizabeth; Skenderis, Kostas
2017-01-27
We test a class of holographic models for the very early Universe against cosmological observations and find that they are competitive to the standard cold dark matter model with a cosmological constant (ΛCDM) of cosmology. These models are based on three-dimensional perturbative superrenormalizable quantum field theory (QFT), and, while they predict a different power spectrum from the standard power law used in ΛCDM, they still provide an excellent fit to the data (within their regime of validity). By comparing the Bayesian evidence for the models, we find that ΛCDM does a better job globally, while the holographic models provide a (marginally) better fit to the data without very low multipoles (i.e., l≲30), where the QFT becomes nonperturbative. Observations can be used to exclude some QFT models, while we also find models satisfying all phenomenological constraints: The data rule out the dual theory being a Yang-Mills theory coupled to fermions only but allow for a Yang-Mills theory coupled to nonminimal scalars with quartic interactions. Lattice simulations of 3D QFTs can provide nonperturbative predictions for large-angle statistics of the cosmic microwave background and potentially explain its apparent anomalies.
Riles, K
1998-01-01
The Large Electron Project (LEP) accelerator near Geneva, more than any other instrument, has rigorously tested the predictions of the Standard Model of elementary particles. LEP measurements have probed the theory from many different directions and, so far, the Standard Model has prevailed. The rigour of these tests has allowed LEP physicists to determine unequivocally the number of fundamental 'generations' of elementary particles. These tests also allowed physicists to ascertain the mass of the top quark in advance of its discovery. Recent increases in the accelerator's energy allow new measurements to be undertaken, measurements that may uncover directly or indirectly the long-sought Higgs particle, believed to impart mass to all other particles.
Averaging of the Equations of the Standard Cosmological Model over Rapid Oscillations
Ignat'ev, Yu. G.; Samigullina, A. R.
2017-11-01
An averaging of the equations of the standard cosmological model (SCM) is carried out. It is shown that the main contribution to the macroscopic energy density of the scalar field comes from its microscopic oscillations with the Compton period. The effective macroscopic equation of state of the oscillations of the scalar field corresponds to the nonrelativistic limit.
Ambiguous tests of general relativity on cosmological scales
International Nuclear Information System (INIS)
Zuntz, Joe; Baker, Tessa; Ferreira, Pedro G.; Skordis, Constantinos
2012-01-01
There are a number of approaches to testing General Relativity (GR) on linear scales using parameterized frameworks for modifying cosmological perturbation theory. It is sometimes assumed that the details of any given parameterization are unimportant if one uses it as a diagnostic for deviations from GR. In this brief report we argue that this is not necessarily so. First we show that adopting alternative combinations of modifications to the field equations significantly changes the constraints that one obtains. In addition, we show that using a parameterization with insufficient freedom significantly tightens the apparent theoretical constraints. Fundamentally we argue that it is almost never appropriate to consider modifications to the perturbed Einstein equations as being constraints on the effective gravitational constant, for example, in the same sense that solar system constraints are. The only consistent modifications are either those that grant near-total freedom, as in decomposition methods, or ones which map directly to a particular part of theory space
Cosmology and Particle Physics beyond Standard Models Ten Years of the SEENET-MTP Network
Álvarez-Gaumé, Luis; Stojkovic, Dejan
2014-01-01
This publication - "Cosmology and Particle Physics beyond Standard Models" - is dedicated to the celebration of the tenth anniversary of the Southeastern European Network in Mathematical and Theoretical Physics (SEENET-MTP). As a Theme Collection, rather than a Monograph or Proceedings, this volume presents a number of reports and overviews, a few research papers and a short note. However, some of them are excellent examples of a nowadays increasingly deep interplay between particle physics and cosmology. Contributions span a wide range of topics in cosmology, particle physics, but also gravity, including the interface of these fields. The presented work is of both theoretical and experimental/ observational nature. The contributions represent recent progress in their respective fields: inflation, dark matter, neutrino physics, supersymmetry, collider physics, string theory, quantum gravity, black hole physics and massive gravity.
Gonzalez-Mestres, L.
2014-04-01
Detailed analyses of WMAP and Planck data can have significant implications for noncyclic pre-Big Bang approaches incorporating a new fundamental scale beyond the Planck scale and, potentially, new ultimate constituents of matter with unconventional basic properties as compared to standard particles. Cosmic-ray experiments at the highest energies can also yield relevant information. Hopefully, future studies will be able to deal with alternatives: i) to standard physics for the structure of the physical vacuum, the nature of space-time, the validity of quantum field theory and conventional symmetries, the interpretation of string-like theories...; ii) to standard cosmology concerning the origin and evolution of our Universe, unconventional solutions to the cosmological constant problem, the validity of inflationary scenarios, the need for dark matter and dark energy... Lorentz-like symmetries for the properties of matter can then be naturally stable space-time configurations resulting from more general primordial scenarios that incorporate physics beyond the Planck scale and describe the formation and evolution of the physical vacuum. A possible answer to the question of the origin of half-integer spins can be provided by a primordial spinorial space-time with two complex coordinates instead of the conventional four real ones, leading to a really new cosmology. We discuss basic questions and phenomenological topics concerning noncyclic pre-Big Bang cosmologies and potentially related physics.
Espinosa, J R; Racco, D; Riotto, A
2018-03-23
For the current central values of the Higgs boson and top quark masses, the standard model Higgs potential develops an instability at a scale of the order of 10^{11} GeV. We show that a cosmological signature of such instability could be dark matter in the form of primordial black holes seeded by Higgs fluctuations during inflation. The existence of dark matter might not require physics beyond the standard model.
Espinosa, J. R.; Racco, D.; Riotto, A.
2018-03-01
For the current central values of the Higgs boson and top quark masses, the standard model Higgs potential develops an instability at a scale of the order of 1 011 GeV . We show that a cosmological signature of such instability could be dark matter in the form of primordial black holes seeded by Higgs fluctuations during inflation. The existence of dark matter might not require physics beyond the standard model.
Dynamical friction: The Hubble diagram as a cosmological test
International Nuclear Information System (INIS)
Gunn, J.E.; Tinsley, B.M.
1976-01-01
Effects on the Hubble diagram of the frictional accretion of small cluster galaxies by large ones, to which Ostriker and Tremaine have recently drawn attention, must be accurately determined if the magnitude-redshift relation is to become a viable cosmological test. We find that the process might be detectable through the concomitant change in galaxy colors, but that its effect on the dispersion of magnitudes of first-ranked cluster galaxies would be negligible even if the change in average magnitude is very important. The sign of the effect of accretion on the luminosity observed within a given aperture depends on the structures of the galaxies involved. The size of the effect not only depends sensitively on the galaxy structures, but is also amplified when the relatively recent collapse times of the clusters are taken into account. It is vital to answer the complicated observational and theoretical questions raised by these preliminary calculations, because the Hubble diagram remains the most promising approach to the deceleration parameter q 0 . Local tests of the density of the universe do not give equivalent information
Using quasars as standard clocks for measuring cosmological redshift.
Dai, De-Chang; Starkman, Glenn D; Stojkovic, Branislav; Stojkovic, Dejan; Weltman, Amanda
2012-06-08
We report hitherto unnoticed patterns in quasar light curves. We characterize segments of the quasar's light curves with the slopes of the straight lines fit through them. These slopes appear to be directly related to the quasars' redshifts. Alternatively, using only global shifts in time and flux, we are able to find significant overlaps between the light curves of different pairs of quasars by fitting the ratio of their redshifts. We are then able to reliably determine the redshift of one quasar from another. This implies that one can use quasars as standard clocks, as we explicitly demonstrate by constructing two independent methods of finding the redshift of a quasar from its light curve.
LINKING TESTS OF GRAVITY ON ALL SCALES: FROM THE STRONG-FIELD REGIME TO COSMOLOGY
Energy Technology Data Exchange (ETDEWEB)
Baker, Tessa [Astrophysics, Denys Wilkinson Building, Keble Road, University of Oxford, Oxford, OX1 3RH (United Kingdom); Psaltis, Dimitrios [Astronomy Department, University of Arizona, 933 North Cherry Avenue., Tucson, AZ 85721 (United States); Skordis, Constantinos, E-mail: tessa.baker@astro.ox.ac.uk, E-mail: dpsaltis@email.arizona.edu, E-mail: skordis@ucy.ac.cy [School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom)
2015-03-20
The current effort to test general relativity (GR) employs multiple disparate formalisms for different observables, obscuring the relations between laboratory, astrophysical, and cosmological constraints. To remedy this situation, we develop a parameter space for comparing tests of gravity on all scales in the universe. In particular, we present new methods for linking cosmological large-scale structure, the cosmic microwave background, and gravitational waves with classic PPN tests of gravity. Diagrams of this gravitational parameter space reveal a noticeable untested regime. The untested window, which separates small-scale systems from the troubled cosmological regime, could potentially hide the onset of corrections to GR.
The New Era of Precision Cosmology: Testing Gravity at Large Scales
Prescod-Weinstein, Chanda
2011-01-01
Cosmic acceleration may be the biggest phenomenological mystery in cosmology today. Various explanations for its cause have been proposed, including the cosmological constant, dark energy and modified gravities. Structure formation provides a strong test of any cosmic acceleration model because a successful dark energy model must not inhibit the development of observed large-scale structures. Traditional approaches to studies of structure formation in the presence of dark energy ore modified gravity implement the Press & Schechter formalism (PGF). However, does the PGF apply in all cosmologies? The search is on for a better understanding of universality in the PGF In this talk, I explore the potential for universality and talk about what dark matter haloes may be able to tell us about cosmology. I will also discuss the implications of this and new cosmological experiments for better understanding our theory of gravity.
International Nuclear Information System (INIS)
Artymowski, Michał; Lewicki, Marek; Wells, James D.
2017-01-01
We consider various models realizing baryogenesis during the electroweak phase transition (EWBG). Our focus is their possible detection in future collider experiments and possible observation of gravitational waves emitted during the phase transition. We also discuss the possibility of a non-standard cosmological history which can facilitate EWBG. We show how acceptable parameter space can be extended due to such a modification and conclude that next generation precision experiments such as the ILC will be able to confirm or falsify many models realizing EWBG. We also show that, in general, collider searches are a more powerful probe than gravitational wave searches. However, observation of a deviation from the SM without any hints of gravitational waves can point to models with modified cosmological history that generically enable EWBG with weaker phase transition and thus, smaller GW signals.
Energy Technology Data Exchange (ETDEWEB)
Artymowski, Michał [Jagiellonian University,Łojasiewicza 11, 30-348 Kraków (Poland); Lewicki, Marek [Faculty of Physics, University of Warsaw,ul. Pasteura 5, 02-093 Warsaw (Poland); Michigan Center for Theoretical Physics, University of Michigan,Ann Arbor MI 48109 (United States); Wells, James D. [Michigan Center for Theoretical Physics, University of Michigan,Ann Arbor MI 48109 (United States); Deutsches Elektronen-Synchrotron DESY, Theory Group,D-22603 Hamburg (Germany)
2017-03-13
We consider various models realizing baryogenesis during the electroweak phase transition (EWBG). Our focus is their possible detection in future collider experiments and possible observation of gravitational waves emitted during the phase transition. We also discuss the possibility of a non-standard cosmological history which can facilitate EWBG. We show how acceptable parameter space can be extended due to such a modification and conclude that next generation precision experiments such as the ILC will be able to confirm or falsify many models realizing EWBG. We also show that, in general, collider searches are a more powerful probe than gravitational wave searches. However, observation of a deviation from the SM without any hints of gravitational waves can point to models with modified cosmological history that generically enable EWBG with weaker phase transition and thus, smaller GW signals.
Benoit-Lévy, Aurélien; Chardin, Gabriel
2014-05-01
We study an unconventional cosmology, in which we investigate the consequences that antigravity would pose to cosmology. We present the main characteristics of the Dirac-Milne Universe, a cosmological model where antimatter has a negative active gravitational mass. In this non-standard Universe, separate domains of matter and antimatter coexist at our epoch without annihilation, separated by a gravitationally induced depletion zone. We show that this cosmology does not require a priori the Dark Matter and Dark Energy components of the standard model of cosmology. Additionally, inflation becomes an unnecessary ingredient. Investigating this model, we show that the classical cosmological tests such as primordial nucleosynthesis, Type Ia supernovæ and Cosmic Microwave Background are surprisingly concordant.
A tomographic test of cosmological principle using the JLA compilation of type Ia supernovae
Chang, Zhe; Lin, Hai-Nan; Sang, Yu; Wang, Sai
2018-05-01
We test the cosmological principle by fitting a dipolar modulation of distance modulus and searching for an evolution of this modulation with respect to cosmological redshift. Based on a redshift tomographic method, we divide the Joint Light-curve Analysis compilation of supernovae of type Ia into different redshift bins, and employ a Markov-Chain Monte-Carlo method to infer the anisotropic amplitude and direction in each redshift bin. However, we do not find any significant deviations from the cosmological principle, and the anisotropic amplitude is stringently constrained to be less than a few thousandths at 95% confidence level.
Introduction to gravity and cosmology
International Nuclear Information System (INIS)
Jauneau, L.
1988-09-01
Relativity principles, equivalence principles, and the general covariance principle are introduced. Curved space analysis via tensor calculus and absolute differential calculus is outlined. Einstein's equations are presented. The Schwarzschild solution; tests of general relativity; and black holes are discussed. Application of general relativity to cosmology is considered. The Standard Model of cosmology and its extensions are reviewed
Beyond concordance cosmology with magnification of gravitational-wave standard sirens.
Camera, Stefano; Nishizawa, Atsushi
2013-04-12
We show how future gravitational-wave detectors would be able to discriminate between the concordance Λ cold dark matter cosmological model and up-to-date competing alternatives, e.g., dynamical dark energy (DE) models or modified gravity (MG) theories. Our method consists of using the weak-lensing magnification effect that affects a standard-siren signal because of its traveling through the Universe's large scale structure. As a demonstration, we present constraints on DE and MG from proposed gravitational-wave detectors, namely Einstein Telescope and DECI-Hertz Interferometer Gravitational-Wave Observatory and Big-Bang Observer.
Directory of Open Access Journals (Sweden)
Astri Adelia
2018-06-01
Full Text Available In managing contact dermatitis, identification of the causative agent is essential to prevent recurrent complaints. Patch test is the gold standard to identify the causative agent. Nowadays, there are many patch test standard materials available in the market, but do not include all the materials that potentially cause contact dermatitis. Patch test using patient’s own products or later we refer to as non-standard materials, is very helpful in identifying the causative agents of contact dermatitis. Guidance is needed in producing non-standard patch test materials in order to avoid test results discrepancy.
Brandenberger, Robert H.
2008-01-01
String gas cosmology is a string theory-based approach to early universe cosmology which is based on making use of robust features of string theory such as the existence of new states and new symmetries. A first goal of string gas cosmology is to understand how string theory can effect the earliest moments of cosmology before the effective field theory approach which underlies standard and inflationary cosmology becomes valid. String gas cosmology may also provide an alternative to the curren...
Starting the universe: Stable violation of the null energy condition and non-standard cosmologies
International Nuclear Information System (INIS)
Creminelli, P.; Luty, M.A.; Nicolis, A.; Senatore, L.
2006-06-01
We present a consistent effective theory that violates the null energy condition (NEC) without developing any instabilities or other pathological features. The model is the ghost condensate with the global shift symmetry softly broken by a potential. We show that this system can drive a cosmological expansion with H-dot > 0. Demanding the absence of instabilities in this model requires H-dot or approx. H 2 . We then construct a general low-energy effective theory that describes scalar fluctuations about an arbitrary FRW background, and argue that the qualitative features found in our model are very general for stable systems that violate the NEC. Violating the NEC allows dramatically non- standard cosmological histories. To illustrate this, we construct an explicit model in which the expansion of our universe originates from an asymptotically flat state in the past, smoothing out the big-bang singularity within control of a low- energy effective theory. This gives an interesting alternative to standard inflation for solving the horizon problem. We also construct models in which the present acceleration has w < -1; a periodic ever-expanding universe; and a model with a smooth 'bounce' connecting a contracting and expanding phase. (author)
Tests on standard concrete samples
CERN PhotoLab
1973-01-01
Compression and tensile tests on standard concrete samples. The use of centrifugal force in tensile testing has been developed by the SB Division and the instruments were built in the Central workshops.
Super-Eddington accreting massive black holes as long-lived cosmological standards.
Wang, Jian-Min; Du, Pu; Valls-Gabaud, David; Hu, Chen; Netzer, Hagai
2013-02-22
Super-Eddington accreting massive black holes (SEAMBHs) reach saturated luminosities above a certain accretion rate due to photon trapping and advection in slim accretion disks. We show that these SEAMBHs could provide a new tool for estimating cosmological distances if they are properly identified by hard x-ray observations, in particular by the slope of their 2-10 keV continuum. To verify this idea we obtained black hole mass estimates and x-ray data for a sample of 60 narrow line Seyfert 1 galaxies that we consider to be the most promising SEAMBH candidates. We demonstrate that the distances derived by the new method for the objects in the sample get closer to the standard luminosity distances as the hard x-ray continuum gets steeper. The results allow us to analyze the requirements for using the method in future samples of active black holes and to demonstrate that the expected uncertainty, given large enough samples, can make them into a useful, new cosmological ruler.
How robust are the constraints on cosmology and galaxy evolution from the lens-redshift test?
International Nuclear Information System (INIS)
Capelo, Pedro R; Natarajan, Priyamvada
2007-01-01
The redshift distribution of galaxy lenses in known gravitational lens systems provides a powerful test that can potentially discriminate amongst cosmological models. However, applications of this elegant test have been curtailed by two factors: our ignorance of how galaxies evolve with redshift, and the absence of methods to deal with the effect of incomplete information in lensing systems. In this paper, we investigate both issues in detail. We explore how to extract the properties of evolving galaxies, assuming that the cosmology is well determined by other techniques. We propose a new nested Monte Carlo method to quantify the effects of incomplete data. We apply the lens-redshift test to an improved sample of seventy lens systems derived from recent observations, primarily from the SDSS, SLACS and the CLASS surveys. We find that the limiting factor in applying the lens-redshift test derives from poor statistics, including incomplete information samples and biased sampling. Many lenses that uniformly sample the underlying true image separation distribution will be needed to use this test as a complementary method to measure the value of the cosmological constant or the properties of evolving galaxies. Planned future surveys by missions like the SNAP satellite or LSST are likely to usher in a new era for strong lensing studies that utilize this test. With expected catalogues of thousands of new strong lenses, the lens-redshift test could offer a powerful tool to probe cosmology as well as galaxy evolution
How robust are the constraints on cosmology and galaxy evolution from the lens-redshift test?
Energy Technology Data Exchange (ETDEWEB)
Capelo, Pedro R [Astronomy Department, Yale University, PO Box 208101, New Haven, CT 06520-8101 (United States); Natarajan, Priyamvada [Astronomy Department, Yale University, PO Box 208101, New Haven, CT 06520-8101 (United States)
2007-12-15
The redshift distribution of galaxy lenses in known gravitational lens systems provides a powerful test that can potentially discriminate amongst cosmological models. However, applications of this elegant test have been curtailed by two factors: our ignorance of how galaxies evolve with redshift, and the absence of methods to deal with the effect of incomplete information in lensing systems. In this paper, we investigate both issues in detail. We explore how to extract the properties of evolving galaxies, assuming that the cosmology is well determined by other techniques. We propose a new nested Monte Carlo method to quantify the effects of incomplete data. We apply the lens-redshift test to an improved sample of seventy lens systems derived from recent observations, primarily from the SDSS, SLACS and the CLASS surveys. We find that the limiting factor in applying the lens-redshift test derives from poor statistics, including incomplete information samples and biased sampling. Many lenses that uniformly sample the underlying true image separation distribution will be needed to use this test as a complementary method to measure the value of the cosmological constant or the properties of evolving galaxies. Planned future surveys by missions like the SNAP satellite or LSST are likely to usher in a new era for strong lensing studies that utilize this test. With expected catalogues of thousands of new strong lenses, the lens-redshift test could offer a powerful tool to probe cosmology as well as galaxy evolution.
Sanders, RH; Papantonopoulos, E
2005-01-01
I discuss the classical cosmological tests, i.e., angular size-redshift, flux-redshift, and galaxy number counts, in the light of the cosmology prescribed by the interpretation of the CMB anisotropies. The discussion is somewhat of a primer for physicists, with emphasis upon the possible systematic
Jones, Bernard J. T.
2017-04-01
Preface; Notation and conventions; Part I. 100 Years of Cosmology: 1. Emerging cosmology; 2. The cosmic expansion; 3. The cosmic microwave background; 4. Recent cosmology; Part II. Newtonian Cosmology: 5. Newtonian cosmology; 6. Dark energy cosmological models; 7. The early universe; 8. The inhomogeneous universe; 9. The inflationary universe; Part III. Relativistic Cosmology: 10. Minkowski space; 11. The energy momentum tensor; 12. General relativity; 13. Space-time geometry and calculus; 14. The Einstein field equations; 15. Solutions of the Einstein equations; 16. The Robertson-Walker solution; 17. Congruences, curvature and Raychaudhuri; 18. Observing and measuring the universe; Part IV. The Physics of Matter and Radiation: 19. Physics of the CMB radiation; 20. Recombination of the primeval plasma; 21. CMB polarisation; 22. CMB anisotropy; Part V. Precision Tools for Precision Cosmology: 23. Likelihood; 24. Frequentist hypothesis testing; 25. Statistical inference: Bayesian; 26. CMB data processing; 27. Parametrising the universe; 28. Precision cosmology; 29. Epilogue; Appendix A. SI, CGS and Planck units; Appendix B. Magnitudes and distances; Appendix C. Representing vectors and tensors; Appendix D. The electromagnetic field; Appendix E. Statistical distributions; Appendix F. Functions on a sphere; Appendix G. Acknowledgements; References; Index.
Measuring the cosmological constant through the Lyman-alpha forest using the Alcock-Paczynski test
Lin, Wen-Ching
An important topic in cosmology is the determination of the energy densities of the major components of the Universe---OB, O DM and OΛ. Among these, the cosmological constant OΛ, which associates with the vacuum energy of our universe, draws specific attentions for its importance in fundamental particle physics. The Lyalpha forest QSO spectra are observationally available from z ˜ 0 to z ˜ 4. Recently the concept of performing the Alcock-Paczynski test on the Lyalpha forest to determine the cosmological constant has been proposed. This motivates us to develop a methodology incorporating sophisticated cosmological hydrodynamics simulations including these effects to implement the AP test and to perform an accurate measurement on the cosmological constant O Λ. To manipulate the data from paired QSO spectra with different angular separations, we propose an explicit method based on the maximum likelihood estimation. We use this method to implement the AP test and demonstrate the whole procedure based on our numerical simulations. Using mock pair spectra, we estimate that more than 40 pairs are required to derive an accurate value of OΛ due to the impact of cosmic variance. The degeneracy of other cosmological parameters is an important topic for this project. We examine two other parameters, sigma8 and n, the initial power spectrum amplitude and index, whose value are not consistently derived through other means. We conclude that when the uncertainties of these two parameters are around 10%--20%, the resulting bias in O Λ is less than 10%. Using a small sample of currently available QSO pairs, we have derived OΛ = 0.65+0.39-1.16 . Our preliminary result encourges us to take further steps on this project.
Darling, Jeremy
A new field of study, "real-time cosmology," is now possible. This involves observing a dynamic universe that can be seen to change over human timescales. Most cosmological observations are geometrical, using standard candles or rulers to measure the expansion history and curvature as light propagates through the universe. Real-time cosmological measurements are dynamical, revealing the changing geometry of the universe - thus often providing geometrical distances independent of the canonical cosmological distance ladder - and are typically orthogonal to customary cosmological tests. This field of inquiry is no longer far-fetched, and this proposal demonstrates using extant data that many types of measurement are now within a factor of a few of being detectable, but the theory will very soon lag the observational capabilities. The Gaia mission will provide astrometry and proper motions of roughly 100 microarcseconds per year for half a million quasars by the end of its 5-year mission, but the theory for how to employ these data for cosmological tests has not been established. This project will develop the theory, models, and methods needed to make optimal use of the Gaia extragalactic proper motion measurements and to make significant new cosmological tests, distance measurements, and mass measurements. Gaia data can provide rich cosmological tests that are nearly model-independent. This work will build the theoretical framework enabling Gaia to measure or constrain: (1) The real-time growth and recession of structures, providing mass and distance measurements, (2) Extragalactic parallax for a statistical sample and individual galaxies, thus providing geometric distances, (3) The primordial stochastic long-period gravitational wave background, which deflects quasar light in a quadrupolar proper motion pattern, and (4) Cosmic shear, rotation, bulk motion, and local voids that may manifest as an apparent acceleration attributed to dark energy. One can also test the
Standard Test Method for Sandwich Corrosion Test
American Society for Testing and Materials. Philadelphia
2009-01-01
1.1 This test method defines the procedure for evaluating the corrosivity of aircraft maintenance chemicals, when present between faying surfaces (sandwich) of aluminum alloys commonly used for aircraft structures. This test method is intended to be used in the qualification and approval of compounds employed in aircraft maintenance operations. 1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information. 1.3 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific hazard statements appear in Section 9.
Particle physics and cosmology beyond the Standard Model: inflation, dark matter and flavour
International Nuclear Information System (INIS)
Heurtier, L.
2015-01-01
This thesis has been focusing on beyond the Standard Model aspects of particle physics and their implication in cosmology. We have gone through this work along the timeline of the Universe History focusing on three major topics that are the inflationary period, the dark matter relic density production and detection, and finally the question of flavor changing constraints on low energy supersymmetric theories. In the first part of this thesis, after reviewing the theoretical and phenomenological aspects of both the Big Bang theory and the theory of Inflation we will study in detail how describing Inflation in a high energy supersymmetric theory. The second part of this thesis is dedicated to dark matter. We have studied phenomenological aspects of simple models, extending the present Standard Model with simple abelian symmetries, by assuming that the constituent of dark matter would be able to exchange information with the visible sector by the help of a mediator particle. We have studied in particular possible interactions of heavy or light dark matter with respectively the strong and the electroweak sectors of the Standard Model. Our models are strongly constrained of course by experiments. The third part of this work will be dedicated to a different aspect of beyond Standard Model theories, that is the treatment of the flavour changing processes of particle physics. The Minimal Supersymmetric Standard Model (MSSM), as one of these possible enlargement of the Standard Model, introduces new processes of flavour changing that are highly constrained by experiment. We present some works in which we consider the possibility of adding so called Dirac Gauginos to the MSSM to render flavour changing weaker in the theory, and propose different flavour patterns theories
Narlikar, Jayant Vishnu
2002-01-01
The third edition of this successful textbook is fully updated and includes important recent developments in cosmology. It begins with an introduction to cosmology and general relativity, and goes on to cover the mathematical models of standard cosmology. The physical aspects of cosmology, including primordial nucleosynthesis, the astroparticle physics of inflation, and the current ideas on structure formation are discussed. Alternative models of cosmology are reviewed, including the model of Quasi-Steady State Cosmology, which has recently been proposed as an alternative to Big Bang Cosmology.
Standardized waste form test methods
International Nuclear Information System (INIS)
Slate, S.C.
1984-11-01
The Materials Characterization Center (MCC) is developing standard tests to characterize nuclear waste forms. Development of the first thirteen tests was originally initiated to provide data to compare different high-level waste (HLW) forms and to characterize their basic performance. The current status of the first thirteen MCC tests and some sample test results is presented: The radiation stability tests (MCC-6 and 12) and the tensile-strength test (MCC-11) are approved; the static leach tests (MCC-1, 2, and 3) are being reviewed for full approval; the thermal stability (MCC-7) and microstructure evaluation (MCC-13) methods are being considered for the first time; and the flowing leach tests methods (MCC-4 and 5), the gas generation methods (MCC-8 and 9), and the brittle fracture method (MCC-10) are indefinitely delayed. Sample static leach test data on the ARM-1 approved reference material are presented. Established tests and proposed new tests will be used to meet new testing needs. For waste form production, tests on stability and composition measurement are needed to provide data to ensure waste form quality. In transportation, data are needed to evaluate the effects of accidents on canisterized waste forms. The new MCC-15 accident test method and some data are presented. Compliance testing needs required by the recent draft repository waste acceptance specifications are described. These specifications will control waste form contents, processing, and performance. 2 references, 2 figures
Standardized waste form test methods
International Nuclear Information System (INIS)
Slate, S.C.
1984-01-01
The Materials Characterization Center (MCC) is developing standard tests to characterize nuclear waste forms. Development of the first thirteen tests was originally initiated to provide data to compare different high-level waste (HLW) forms and to characterize their basic performance. The current status of the first thirteen MCC tests and some sample test results are presented: the radiation stability tests (MCC-6 and 12) and the tensile-strength test (MCC-11) are approved; the static leach tests (MCC-1, 2, and 3) are being reviewed for full approval; the thermal stability (MCC-7) and microstructure evaluation (MCC-13) methods are being considered for the first time; and the flowing leach test methods (MCC-4 and 5), the gas generation methods (MCC-8 and 9), and the brittle fracture method (MCC-10) are indefinitely delayed. Sample static leach test data on the ARM-1 approved reference material are presented. Established tests and proposed new tests will be used to meet new testing needs. For waste form production, tests on stability and composition measurement are needed to provide data to ensure waste form quality. In transporation, data are needed to evaluate the effects of accidents on canisterized waste forms. The new MCC-15 accident test method and some data are presented. Compliance testing needs required by the recent draft repository waste acceptance specifications are described. These specifications will control waste form contents, processing, and performance
Cosmology and particle physics
International Nuclear Information System (INIS)
Turner, M.S.
1985-01-01
The author reviews the standard cosmology, focusing on primordial nucleosynthesis, and discusses how the standard cosmology has been used to place constraints on the properties of various particles. Baryogenesis is examined in which the B, C, CP violating interactions in GUTs provide a dynamical explanation for the predominance of matter over antimatter and the present baryon-to-baryon ratio. Monoposes, cosmology and astrophysics are reviewed. The author also discusses supersymmetry/supergravity and cosmology, superstrings and cosmology in extra dimensions, and axions, astrophics, and cosmology
Lesgourgues, Julien; Miele, Gennaro; Pastor, Sergio
2013-01-01
The role that neutrinos have played in the evolution of the Universe is the focus of one of the most fascinating research areas that has stemmed from the interplay between cosmology, astrophysics and particle physics. In this self-contained book, the authors bring together all aspects of the role of neutrinos in cosmology, spanning from leptogenesis to primordial nucleosynthesis, their role in CMB and structure formation, to the problem of their direct detection. The book starts by guiding the reader through aspects of fundamental neutrino physics, such as the standard cosmological model and the statistical mechanics in the expanding Universe, before discussing the history of neutrinos in chronological order from the very early stages until today. This timely book will interest graduate students and researchers in astrophysics, cosmology and particle physics, who work with either a theoretical or experimental focus.
Testing dark energy and dark matter cosmological models with clusters of galaxies
Energy Technology Data Exchange (ETDEWEB)
Boehringer, Hans [Max-Planck-Institut fuer Extraterrestrische Physik, Garching (Germany)
2008-07-01
Galaxy clusters are, as the largest building blocks of our Universe, ideal probes to study the large-scale structure and to test cosmological models. The principle approach und the status of this research is reviewed. Clusters lend themselves for tests in serveral ways: the cluster mass function, the spatial clustering, the evolution of both functions with reshift, and the internal composition can be used to constrain cosmological parameters. X-ray observations are currently the best means of obtaining the relevant data on the galaxy cluster population. We illustrate in particular all the above mentioned methods with our ROSAT based cluster surveys. The mass calibration of clusters is an important issue, that is currently solved with XMM-Newton and Chandra studies. Based on the current experience we provide an outlook for future research, especially with eROSITA.
The generalized cosmic equation of state. A revised study with cosmological standard rulers
Energy Technology Data Exchange (ETDEWEB)
Ma, Yubo [Shanxi Datong University, School of Physics, Datong (China); Zhang, Jia [Weinan Normal University, Department of Physics, School of Mathematics and Physics, Weinan, Shanxi (China); Cao, Shuo; Zheng, Xiaogang; Xu, Tengpeng; Qi, Jingzhao [Beijing Normal University, Department of Astronomy, Beijing (China)
2017-12-15
In this paper, the generalized equation of state (GEoS) for dark energy (w{sub β} = w{sub 0} - w{sub β}[(1+z){sup -β} - 1]/β) is investigated with the combined standard ruler data from the observations of intermediate-luminosity radio quasars, galaxy clusters, BAO and CMB. The constraint results show that the best-fit EoS parameters are w{sub 0} = -0.94{sup +0.57}{sub -0.41}, w{sub β} = -0.17{sup +2.45}{sub -4.81} and β = -1.42 (with a lower limit of β > -2.70 at 68.3% C.L.), which implies that at early times the dark energy vanishes. In the framework of nine truncated GEoS models with different β parameters, our findings present very clear evidence disfavoring the case that dark energy always dominates over the other material components in the early universe. Moreover, stringent constraints can be obtained in combination with the latest measurements of Hubble parameter at different redshifts: w{sub 0} = -1.01{sup +0.56}{sub -0.31}, w{sub β} = 0.01{sup +2.33}{sub -4.52} and β = -0.42 (with a lower limit of β > -2.40 at 68.3% C.L.). Finally, the results obtained from the transition redshift (z{sub t}) and Om(z) diagnostic indicate that: (1) The above constraints on the GEoS model agree very well with the transition redshift interval 0.49 ≤ z{sub t} ≤ 0.88 within 1σ error region. (2) At the current observational level, the GEoS model is practically indistinguishable from ΛCDM, although a small deviation from ΛCDM cosmology is present in the combined standard ruler data. (orig.)
Testing approximate predictions of displacements of cosmological dark matter halos
Energy Technology Data Exchange (ETDEWEB)
Munari, Emiliano; Monaco, Pierluigi; Borgani, Stefano [Department of Physics, Astronomy Unit, University of Trieste, via Tiepolo 11, I-34143 Trieste (Italy); Koda, Jun [INAF – Osservatorio Astronomico di Brera, via E. Bianchi 46, I-23807 Merate (Italy); Kitaura, Francisco-Shu [Instituto de Astrofísica de Canarias, 38205 San Cristóbal de La Laguna, Santa Cruz de Tenerife (Spain); Sefusatti, Emiliano, E-mail: munari@oats.inaf.it, E-mail: monaco@oats.inaf.it, E-mail: jun.koda@brera.inaf.it, E-mail: fkitaura@iac.es, E-mail: sefusatti@oats.inaf.it, E-mail: borgani@oats.inaf.it [INAF – Osservatorio Astronomico di Trieste, via Tiepolo 11, I-34143 Trieste (Italy)
2017-07-01
We present a test to quantify how well some approximate methods, designed to reproduce the mildly non-linear evolution of perturbations, are able to reproduce the clustering of DM halos once the grouping of particles into halos is defined and kept fixed. The following methods have been considered: Lagrangian Perturbation Theory (LPT) up to third order, Truncated LPT, Augmented LPT, MUSCLE and COLA. The test runs as follows: halos are defined by applying a friends-of-friends (FoF) halo finder to the output of an N-body simulation. The approximate methods are then applied to the same initial conditions of the simulation, producing for all particles displacements from their starting position and velocities. The position and velocity of each halo are computed by averaging over the particles that belong to that halo, according to the FoF halo finder. This procedure allows us to perform a well-posed test of how clustering of the matter density and halo density fields are recovered, without asking to the approximate method an accurate reconstruction of halos. We have considered the results at z =0,0.5,1, and we have analysed power spectrum in real and redshift space, object-by-object difference in position and velocity, density Probability Distribution Function (PDF) and its moments, phase difference of Fourier modes. We find that higher LPT orders are generally able to better reproduce the clustering of halos, while little or no improvement is found for the matter density field when going to 2LPT and 3LPT. Augmentation provides some improvement when coupled with 2LPT, while its effect is limited when coupled with 3LPT. Little improvement is brought by MUSCLE with respect to Augmentation. The more expensive particle-mesh code COLA outperforms all LPT methods, and this is true even for mesh sizes as large as the inter-particle distance. This test sets an upper limit on the ability of these methods to reproduce the clustering of halos, for the cases when these objects are
Testing approximate predictions of displacements of cosmological dark matter halos
Munari, Emiliano; Monaco, Pierluigi; Koda, Jun; Kitaura, Francisco-Shu; Sefusatti, Emiliano; Borgani, Stefano
2017-07-01
We present a test to quantify how well some approximate methods, designed to reproduce the mildly non-linear evolution of perturbations, are able to reproduce the clustering of DM halos once the grouping of particles into halos is defined and kept fixed. The following methods have been considered: Lagrangian Perturbation Theory (LPT) up to third order, Truncated LPT, Augmented LPT, MUSCLE and COLA. The test runs as follows: halos are defined by applying a friends-of-friends (FoF) halo finder to the output of an N-body simulation. The approximate methods are then applied to the same initial conditions of the simulation, producing for all particles displacements from their starting position and velocities. The position and velocity of each halo are computed by averaging over the particles that belong to that halo, according to the FoF halo finder. This procedure allows us to perform a well-posed test of how clustering of the matter density and halo density fields are recovered, without asking to the approximate method an accurate reconstruction of halos. We have considered the results at z=0,0.5,1, and we have analysed power spectrum in real and redshift space, object-by-object difference in position and velocity, density Probability Distribution Function (PDF) and its moments, phase difference of Fourier modes. We find that higher LPT orders are generally able to better reproduce the clustering of halos, while little or no improvement is found for the matter density field when going to 2LPT and 3LPT. Augmentation provides some improvement when coupled with 2LPT, while its effect is limited when coupled with 3LPT. Little improvement is brought by MUSCLE with respect to Augmentation. The more expensive particle-mesh code COLA outperforms all LPT methods, and this is true even for mesh sizes as large as the inter-particle distance. This test sets an upper limit on the ability of these methods to reproduce the clustering of halos, for the cases when these objects are
Astrophysical Tests of Kinematical Conformal Cosmology in Fourth-Order Conformal Weyl Gravity
Directory of Open Access Journals (Sweden)
Gabriele U. Varieschi
2014-12-01
Full Text Available In this work we analyze kinematical conformal cosmology (KCC, an alternative cosmological model based on conformal Weyl gravity (CG, and test it against current type Ia supernova (SNIa luminosity data and other astrophysical observations. Expanding upon previous work on the subject, we revise the analysis of SNIa data, confirming that KCC can explain the evidence for an accelerating expansion of the Universe without using dark energy or other exotic components. We obtain an independent evaluation of the Hubble constant, H0 = 67:53 kms-1 Mpc-1, very close to the current best estimates. The main KCC and CG parameters are re-evaluated and their revised values are found to be close to previous estimates. We also show that available data for the Hubble parameter as a function of redshift can be fitted using KCC and that this model does not suffer from any apparent age problem. Overall,
Testing the Copernican and Cosmological Principles in the local universe with galaxy surveys
International Nuclear Information System (INIS)
Sylos Labini, Francesco; Baryshev, Yuri V.
2010-01-01
Cosmological density fields are assumed to be translational and rotational invariant, avoiding any special point or direction, thus satisfying the Copernican Principle. A spatially inhomogeneous matter distribution can be compatible with the Copernican Principle but not with the stronger version of it, the Cosmological Principle which requires the additional hypothesis of spatial homogeneity. We establish criteria for testing that a given density field, in a finite sample at low redshifts, is statistically and/or spatially homogeneous. The basic question to be considered is whether a distribution is, at different spatial scales, self-averaging. This can be achieved by studying the probability density function of conditional fluctuations. We find that galaxy structures in the SDSS samples, the largest currently available, are spatially inhomogeneous but statistically homogeneous and isotropic up to ∼ 100 Mpc/h. Evidences for the breaking of self-averaging are found up to the largest scales probed by the SDSS data. The comparison between the results obtained in volumes of different size allows us to unambiguously conclude that the lack of self-averaging is induced by finite-size effects due to long-range correlated fluctuations. We finally discuss the relevance of these results from the point of view of cosmological modeling
Where the world stands still: turnaround as a strong test of ΛCDM cosmology
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Pavlidou, V.; Tomaras, T.N., E-mail: pavlidou@physics.uoc.gr, E-mail: tomaras@physics.uoc.gr [Department of Physics and ITCP, University of Crete, 71003 Heraklion (Greece)
2014-09-01
Our intuitive understanding of cosmic structure formation works best in scales small enough so that isolated, bound, relaxed gravitating systems are no longer adjusting their radius; and large enough so that space and matter follow the average expansion of the Universe. Yet one of the most robust predictions of ΛCDM cosmology concerns the scale that separates these limits: the turnaround radius, which is the non-expanding shell furthest away from the center of a bound structure. We show that the maximum possible value of the turnaround radius within the framework of the ΛCDM model is, for a given mass M, equal to (3GM/Λ c{sup 2}){sup 1/3}, with G Newton's constant and c the speed of light, independently of cosmic epoch, exact nature of dark matter, or baryonic effects. We discuss the possible use of this prediction as an observational test for ΛCDM cosmology. Current data appear to favor ΛCDM over alternatives with local inhomogeneities and no Λ. However there exist several local-universe structures that have, within errors, reached their limiting size. With improved determinations of their turnaround radii and the enclosed mass, these objects may challenge the limit and ΛCDM cosmology.
Where the world stands still: turnaround as a strong test of ΛCDM cosmology
Pavlidou, V.; Tomaras, T. N.
2014-09-01
Our intuitive understanding of cosmic structure formation works best in scales small enough so that isolated, bound, relaxed gravitating systems are no longer adjusting their radius; and large enough so that space and matter follow the average expansion of the Universe. Yet one of the most robust predictions of ΛCDM cosmology concerns the scale that separates these limits: the turnaround radius, which is the non-expanding shell furthest away from the center of a bound structure. We show that the maximum possible value of the turnaround radius within the framework of the ΛCDM model is, for a given mass M, equal to (3GM/Λ c2)1/3, with G Newton's constant and c the speed of light, independently of cosmic epoch, exact nature of dark matter, or baryonic effects. We discuss the possible use of this prediction as an observational test for ΛCDM cosmology. Current data appear to favor ΛCDM over alternatives with local inhomogeneities and no Λ. However there exist several local-universe structures that have, within errors, reached their limiting size. With improved determinations of their turnaround radii and the enclosed mass, these objects may challenge the limit and ΛCDM cosmology.
Integrated Sachs-Wolfe effect versus redshift test for the cosmological parameters
Kantowski, R.; Chen, B.; Dai, X.
2015-04-01
We describe a method using the integrated Sachs-Wolfe (ISW) effect caused by individual inhomogeneities to determine the cosmological parameters H0, Ωm , and ΩΛ, etc. This ISW-redshift test requires detailed knowledge of the internal kinematics of a set of individual density perturbations, e.g., galaxy clusters and/or cosmic voids, in particular their density and velocity profiles, and their mass accretion rates. It assumes the density perturbations are isolated and embedded (equivalently compensated) and makes use of the newly found relation between the ISW temperature perturbation of the cosmic microwave background (CMB) and the Fermat potential of the lens. Given measurements of the amplitudes of the temperature variations in the CMB caused by such clusters or voids at various redshifts and estimates of their angular sizes or masses, one can constrain the cosmological parameters. More realistically, the converse is more likely, i.e., if the background cosmology is sufficiently constrained, measurement of ISW profiles of clusters and voids (e.g., hot and cold spots and rings) can constrain dynamical properties of the dark matter, including accretion, associated with such lenses and thus constrain the evolution of these objects with redshift.
Testing ΛCDM cosmology at turnaround: where to look for violations of the bound?
International Nuclear Information System (INIS)
Tanoglidis, D.; Pavlidou, V.; Tomaras, T.N.
2015-01-01
In ΛCDM cosmology, structure formation is halted shortly after dark energy dominates the mass/energy budget of the Universe. A manifestation of this effect is that in such a cosmology the turnaround radius—the non-expanding mass shell furthest away from the center of a structure— has an upper bound. Recently, a new, local, test for the existence of dark energy in the form of a cosmological constant was proposed based on this turnaround bound. Before designing an experiment that, through high-precision determination of masses and —independently— turnaround radii, will challenge ΛCDM cosmology, we have to answer two important questions: first, when turnaround-scale structures are predicted to be close enough to their maximum size, so that a possible violation of the bound may be observable. Second, which is the best mass scale to target for possible violations of the bound. These are the questions we address in the present work. Using the Press-Schechter formalism, we find that turnaround structures have in practice already stopped forming, and consequently, the turnaround radius of structures must be very close to the maximum value today. We also find that the mass scale of ∼ 10 13 M ⊙ characterizes the turnaround structures that start to form in a statistically important number density today —and even at an infinite time in the future, since structure formation has almost stopped. This mass scale also separates turnaround structures with qualitatively different cosmological evolution: smaller structures are no longer readjusting their mass distribution inside the turnaround scale, they asymptotically approach their ultimate abundance from higher values, and they are common enough to have, at some epoch, experienced major mergers with structures of comparable mass; larger structures exhibit the opposite behavior. We call this mass scale the transitional mass scale and we argue that it is the optimal for the purpose outlined above. As a corollary
Sanders, Robert H
2016-01-01
The advent of sensitive high-resolution observations of the cosmic microwave background radiation and their successful interpretation in terms of the standard cosmological model has led to great confidence in this model's reality. The prevailing attitude is that we now understand the Universe and need only work out the details. In this book, Sanders traces the development and successes of Lambda-CDM, and argues that this triumphalism may be premature. The model's two major components, dark energy and dark matter, have the character of the pre-twentieth-century luminiferous aether. While there is astronomical evidence for these hypothetical fluids, their enigmatic properties call into question our assumptions of the universality of locally determined physical law. Sanders explains how modified Newtonian dynamics (MOND) is a significant challenge for cold dark matter. Overall, the message is hopeful: the field of cosmology has not become frozen, and there is much fundamental work ahead for tomorrow's cosmologis...
Rajantie, Arttu
2018-03-06
The discovery of the Higgs boson in 2012 and other results from the Large Hadron Collider have confirmed the standard model of particle physics as the correct theory of elementary particles and their interactions up to energies of several TeV. Remarkably, the theory may even remain valid all the way to the Planck scale of quantum gravity, and therefore it provides a solid theoretical basis for describing the early Universe. Furthermore, the Higgs field itself has unique properties that may have allowed it to play a central role in the evolution of the Universe, from inflation to cosmological phase transitions and the origin of both baryonic and dark matter, and possibly to determine its ultimate fate through the electroweak vacuum instability. These connections between particle physics and cosmology have given rise to a new and growing field of Higgs cosmology, which promises to shed new light on some of the most puzzling questions about the Universe as new data from particle physics experiments and cosmological observations become available.This article is part of the Theo Murphy meeting issue 'Higgs cosmology'. © 2018 The Author(s).
Rajantie, Arttu
2018-01-01
The discovery of the Higgs boson in 2012 and other results from the Large Hadron Collider have confirmed the standard model of particle physics as the correct theory of elementary particles and their interactions up to energies of several TeV. Remarkably, the theory may even remain valid all the way to the Planck scale of quantum gravity, and therefore it provides a solid theoretical basis for describing the early Universe. Furthermore, the Higgs field itself has unique properties that may have allowed it to play a central role in the evolution of the Universe, from inflation to cosmological phase transitions and the origin of both baryonic and dark matter, and possibly to determine its ultimate fate through the electroweak vacuum instability. These connections between particle physics and cosmology have given rise to a new and growing field of Higgs cosmology, which promises to shed new light on some of the most puzzling questions about the Universe as new data from particle physics experiments and cosmological observations become available. This article is part of the Theo Murphy meeting issue `Higgs cosmology'.
Nonparametric test of consistency between cosmological models and multiband CMB measurements
Energy Technology Data Exchange (ETDEWEB)
Aghamousa, Amir [Asia Pacific Center for Theoretical Physics, Pohang, Gyeongbuk 790-784 (Korea, Republic of); Shafieloo, Arman, E-mail: amir@apctp.org, E-mail: shafieloo@kasi.re.kr [Korea Astronomy and Space Science Institute, Daejeon 305-348 (Korea, Republic of)
2015-06-01
We present a novel approach to test the consistency of the cosmological models with multiband CMB data using a nonparametric approach. In our analysis we calibrate the REACT (Risk Estimation and Adaptation after Coordinate Transformation) confidence levels associated with distances in function space (confidence distances) based on the Monte Carlo simulations in order to test the consistency of an assumed cosmological model with observation. To show the applicability of our algorithm, we confront Planck 2013 temperature data with concordance model of cosmology considering two different Planck spectra combination. In order to have an accurate quantitative statistical measure to compare between the data and the theoretical expectations, we calibrate REACT confidence distances and perform a bias control using many realizations of the data. Our results in this work using Planck 2013 temperature data put the best fit ΛCDM model at 95% (∼ 2σ) confidence distance from the center of the nonparametric confidence set while repeating the analysis excluding the Planck 217 × 217 GHz spectrum data, the best fit ΛCDM model shifts to 70% (∼ 1σ) confidence distance. The most prominent features in the data deviating from the best fit ΛCDM model seems to be at low multipoles 18 < ℓ < 26 at greater than 2σ, ℓ ∼ 750 at ∼1 to 2σ and ℓ ∼ 1800 at greater than 2σ level. Excluding the 217×217 GHz spectrum the feature at ℓ ∼ 1800 becomes substantially less significance at ∼1 to 2σ confidence level. Results of our analysis based on the new approach we propose in this work are in agreement with other analysis done using alternative methods.
Temple, Blake; Smoller, Joel
2009-08-25
We derive a system of three coupled equations that implicitly defines a continuous one-parameter family of expanding wave solutions of the Einstein equations, such that the Friedmann universe associated with the pure radiation phase of the Standard Model of Cosmology is embedded as a single point in this family. By approximating solutions near the center to leading order in the Hubble length, the family reduces to an explicit one-parameter family of expanding spacetimes, given in closed form, that represents a perturbation of the Standard Model. By introducing a comoving coordinate system, we calculate the correction to the Hubble constant as well as the exact leading order quadratic correction to the redshift vs. luminosity relation for an observer at the center. The correction to redshift vs. luminosity entails an adjustable free parameter that introduces an anomalous acceleration. We conclude (by continuity) that corrections to the redshift vs. luminosity relation observed after the radiation phase of the Big Bang can be accounted for, at the leading order quadratic level, by adjustment of this free parameter. The next order correction is then a prediction. Since nonlinearities alone could actuate dissipation and decay in the conservation laws associated with the highly nonlinear radiation phase and since noninteracting expanding waves represent possible time-asymptotic wave patterns that could result, we propose to further investigate the possibility that these corrections to the Standard Model might be the source of the anomalous acceleration of the galaxies, an explanation not requiring the cosmological constant or dark energy.
International Nuclear Information System (INIS)
Ballesteros, Guillermo; Ringwald, Andreas; Tamarit, Carlos
2016-10-01
We present a minimal extension of the Standard Model (SM) providing a consistent picture of particle physics from the electroweak scale to the Planck scale and of cosmology from inflation until today. Three right-handed neutrinos N_i, a new color triplet Q and a complex SM-singlet scalar σ, whose vacuum expectation value υ_σ∝10"1"1 GeV breaks lepton number and a Peccei-Quinn symmetry simultaneously, are added to the SM. At low energies, the model reduces to the SM, augmented by seesaw generated neutrino masses and mixing, plus the axion. The latter solves the strong CP problem and accounts for the cold dark matter in the Universe. The inflaton is comprised by a mixture of σ and the SM Higgs and reheating of the Universe after inflation proceeds via the Higgs portal. Baryogenesis occurs via thermal leptogenesis. Thus, five fundamental problems of particle physics and cosmology are solved at one stroke in this unified Standard Model-Axion-Seesaw-Higgs portal inflation (SMASH) model. It can be probed decisively by upcoming cosmic microwave background and axion dark matter experiments.
Energy Technology Data Exchange (ETDEWEB)
Ballesteros, Guillermo [Institut de Physique Théorique, Université Paris Saclay, CEA, CNRS, 91191 Gif-sur-Yvette (France); Redondo, Javier [Departamento de Física Teórica, Universidad de Zaragoza, Pedro Cerbuna 12, E-50009, Zaragoza (Spain); Ringwald, Andreas [DESY, Notkestr. 85, 22607 Hamburg (Germany); Tamarit, Carlos, E-mail: guillermo.ballesteros@cea.fr, E-mail: jredondo@unizar.es, E-mail: andreas.ringwald@desy.de, E-mail: carlos.tamarit@durham.ac.uk [Institute for Particle Physics Phenomenology, Durham University, South Road, DH1 3LE (United Kingdom)
2017-08-01
We present a minimal extension of the Standard Model (SM) providing a consistent picture of particle physics from the electroweak scale to the Planck scale and of cosmology from inflation until today. Three right-handed neutrinos N {sub i} , a new color triplet Q and a complex SM-singlet scalar σ, whose vacuum expectation value v {sub σ} ∼ 10{sup 11} GeV breaks lepton number and a Peccei-Quinn symmetry simultaneously, are added to the SM. At low energies, the model reduces to the SM, augmented by seesaw generated neutrino masses and mixing, plus the axion. The latter solves the strong CP problem and accounts for the cold dark matter in the Universe. The inflaton is comprised by a mixture of σ and the SM Higgs, and reheating of the Universe after inflation proceeds via the Higgs portal. Baryogenesis occurs via thermal leptogenesis. Thus, five fundamental problems of particle physics and cosmology are solved at one stroke in this unified Standard Model—axion—seesaw—Higgs portal inflation (SMASH) model. It can be probed decisively by upcoming cosmic microwave background and axion dark matter experiments.
Parameterized post-Newtonian cosmology
International Nuclear Information System (INIS)
Sanghai, Viraj A A; Clifton, Timothy
2017-01-01
Einstein’s theory of gravity has been extensively tested on solar system scales, and for isolated astrophysical systems, using the perturbative framework known as the parameterized post-Newtonian (PPN) formalism. This framework is designed for use in the weak-field and slow-motion limit of gravity, and can be used to constrain a large class of metric theories of gravity with data collected from the aforementioned systems. Given the potential of future surveys to probe cosmological scales to high precision, it is a topic of much contemporary interest to construct a similar framework to link Einstein’s theory of gravity and its alternatives to observations on cosmological scales. Our approach to this problem is to adapt and extend the existing PPN formalism for use in cosmology. We derive a set of equations that use the same parameters to consistently model both weak fields and cosmology. This allows us to parameterize a large class of modified theories of gravity and dark energy models on cosmological scales, using just four functions of time. These four functions can be directly linked to the background expansion of the universe, first-order cosmological perturbations, and the weak-field limit of the theory. They also reduce to the standard PPN parameters on solar system scales. We illustrate how dark energy models and scalar-tensor and vector-tensor theories of gravity fit into this framework, which we refer to as ‘parameterized post-Newtonian cosmology’ (PPNC). (paper)
Parameterized post-Newtonian cosmology
Sanghai, Viraj A. A.; Clifton, Timothy
2017-03-01
Einstein’s theory of gravity has been extensively tested on solar system scales, and for isolated astrophysical systems, using the perturbative framework known as the parameterized post-Newtonian (PPN) formalism. This framework is designed for use in the weak-field and slow-motion limit of gravity, and can be used to constrain a large class of metric theories of gravity with data collected from the aforementioned systems. Given the potential of future surveys to probe cosmological scales to high precision, it is a topic of much contemporary interest to construct a similar framework to link Einstein’s theory of gravity and its alternatives to observations on cosmological scales. Our approach to this problem is to adapt and extend the existing PPN formalism for use in cosmology. We derive a set of equations that use the same parameters to consistently model both weak fields and cosmology. This allows us to parameterize a large class of modified theories of gravity and dark energy models on cosmological scales, using just four functions of time. These four functions can be directly linked to the background expansion of the universe, first-order cosmological perturbations, and the weak-field limit of the theory. They also reduce to the standard PPN parameters on solar system scales. We illustrate how dark energy models and scalar-tensor and vector-tensor theories of gravity fit into this framework, which we refer to as ‘parameterized post-Newtonian cosmology’ (PPNC).
Directory of Open Access Journals (Sweden)
Laszlo A. Marosi
2013-01-01
Full Text Available We present a new redshift (RS versus photon travel time ( test including 171 supernovae RS data points. We extended the Hubble diagram to a range of z = 0,0141–8.1 in the hope that at high RSs, the fitting of the calculated RS/ diagrams to the observed RS data would, as predicted by different cosmological models, set constraints on alternative cosmological models. The Lambda cold dark matter (ΛCDM, the static universe model, and the case for a slowly expanding flat universe (SEU are considered. We show that on the basis of the Hubble diagram test, the static and the slowly expanding models are favored.
Chamcham, Khalil; Silk, Joseph; Barrow, John D.; Saunders, Simon
2017-04-01
Part I. Issues in the Philosophy of Cosmology: 1. Cosmology, cosmologia and the testing of cosmological theories George F. R. Ellis; 2. Black holes, cosmology and the passage of time: three problems at the limits of science Bernard Carr; 3. Moving boundaries? - comments on the relationship between philosophy and cosmology Claus Beisbart; 4. On the question why there exists something rather than nothing Roderich Tumulka; Part II. Structures in the Universe and the Structure of Modern Cosmology: 5. Some generalities about generality John D. Barrow; 6. Emergent structures of effective field theories Jean-Philippe Uzan; 7. Cosmological structure formation Joel R. Primack; 8. Formation of galaxies Joseph Silk; Part III. Foundations of Cosmology: Gravity and the Quantum: 9. The observer strikes back James Hartle and Thomas Hertog; 10. Testing inflation Chris Smeenk; 11. Why Boltzmann brains do not fluctuate into existence from the de Sitter vacuum Kimberly K. Boddy, Sean M. Carroll and Jason Pollack; 12. Holographic inflation revised Tom Banks; 13. Progress and gravity: overcoming divisions between general relativity and particle physics and between physics and HPS J. Brian Pitts; Part IV. Quantum Foundations and Quantum Gravity: 14. Is time's arrow perspectival? Carlo Rovelli; 15. Relational quantum cosmology Francesca Vidotto; 16. Cosmological ontology and epistemology Don N. Page; 17. Quantum origin of cosmological structure and dynamical reduction theories Daniel Sudarsky; 18. Towards a novel approach to semi-classical gravity Ward Struyve; Part V. Methodological and Philosophical Issues: 19. Limits of time in cosmology Svend E. Rugh and Henrik Zinkernagel; 20. Self-locating priors and cosmological measures Cian Dorr and Frank Arntzenius; 21. On probability and cosmology: inference beyond data? Martin Sahlén; 22. Testing the multiverse: Bayes, fine-tuning and typicality Luke A. Barnes; 23. A new perspective on Einstein's philosophy of cosmology Cormac O
The Frontiers of Observational Cosmology and the Confrontation with Theory
International Nuclear Information System (INIS)
Longair, Malcolm
2011-01-01
The current state of observational cosmology and the confrontation with theory is presented. The review is divided into the following sections: - Basic observations on which the models are based. - Testing the basic assumptions made in the construction of the standard cosmological models. - Structure formation in the standard models; - Observational tests of the standard models - the confrontation with observation; - Basic problems and approaches to their solution; - Future challenges - the ESA EUCLID mission is given as an example.
Smoller, Joel; Temple, Blake; Vogler, Zeke
2017-11-01
We identify the condition for smoothness at the centre of spherically symmetric solutions of Einstein's original equations without the cosmological constant or dark energy. We use this to derive a universal phase portrait which describes general, smooth, spherically symmetric solutions near the centre of symmetry when the pressure p=0. In this phase portrait, the critical k=0 Friedmann space-time appears as a saddle rest point which is unstable to spherical perturbations. This raises the question as to whether the Friedmann space-time is observable by redshift versus luminosity measurements looking outwards from any point. The unstable manifold of the saddle rest point corresponding to Friedmann describes the evolution of local uniformly expanding space-times whose accelerations closely mimic the effects of dark energy. A unique simple wave perturbation from the radiation epoch is shown to trigger the instability, match the accelerations of dark energy up to second order and distinguish the theory from dark energy at third order. In this sense, anomalous accelerations are not only consistent with Einstein's original theory of general relativity, but are a prediction of it without the cosmological constant or dark energy.
The hierarchy problem and the cosmological constant problem in the Standard Model
International Nuclear Information System (INIS)
Jegerlehner, Fred
2015-03-01
We argue that the SM in the Higgs phase does not suffer form a ''hierarchy problem'' and that similarly the ''cosmological constant problem'' resolves itself if we understand the SM as a low energy effective theory emerging from a cut-off medium at the Planck scale. We discuss these issues under the condition of a stable Higgs vacuum, which allows to extend the SM up to the Planck length. The bare Higgs boson mass then changes sign below the Planck scale, such the the SM in the early universe is in the symmetric phase. The cut-off enhanced Higgs mass term as well as the quartically enhanced cosmological constant term trigger the inflation of the early universe. The coefficients of the shift between bare and renormalized Higgs mass as well as of the shift between bare and renormalized vacuum energy density exhibit close-by zeros at some point below the Planck scale. The zeros are matching points between short distance and the renormalized low energy quantities. Since inflation tunes the total energy density to take the critical value of a flat universe Ω tot =ρ tot /ρ crit =Ω Λ +Ω matter +Ω radiation =1 it is obvious that Ω Λ today is of order Ω tot given that 1>Ω matter , Ω radiation >0, which saturate the total density to about 26 % only, the dominant part being dark matter(21%).
Smoller, Joel; Temple, Blake; Vogler, Zeke
2017-11-01
We identify the condition for smoothness at the centre of spherically symmetric solutions of Einstein's original equations without the cosmological constant or dark energy. We use this to derive a universal phase portrait which describes general, smooth, spherically symmetric solutions near the centre of symmetry when the pressure p =0. In this phase portrait, the critical k =0 Friedmann space-time appears as a saddle rest point which is unstable to spherical perturbations. This raises the question as to whether the Friedmann space-time is observable by redshift versus luminosity measurements looking outwards from any point. The unstable manifold of the saddle rest point corresponding to Friedmann describes the evolution of local uniformly expanding space-times whose accelerations closely mimic the effects of dark energy. A unique simple wave perturbation from the radiation epoch is shown to trigger the instability, match the accelerations of dark energy up to second order and distinguish the theory from dark energy at third order. In this sense, anomalous accelerations are not only consistent with Einstein's original theory of general relativity, but are a prediction of it without the cosmological constant or dark energy.
Smoller, Joel
2012-01-01
We prove that the Einstein equations in Standard Schwarzschild Coordinates close to form a system of three ordinary differential equations for a family of spherically symmetric, self-similar expansion waves, and the critical ($k=0$) Friedmann universe associated with the pure radiation phase of the Standard Model of Cosmology (FRW), is embedded as a single point in this family. Removing a scaling law and imposing regularity at the center, we prove that the family reduces to an implicitly defined one parameter family of distinct spacetimes determined by the value of a new {\\it acceleration parameter} $a$, such that $a=1$ corresponds to FRW. We prove that all self-similar spacetimes in the family are distinct from the non-critical $k\
Combined cosmological tests of a bivalent tachyonic dark energy scalar field model
International Nuclear Information System (INIS)
Keresztes, Zoltán; Gergely, László Á.
2014-01-01
A recently investigated tachyonic scalar field dark energy dominated universe exhibits a bivalent future: depending on initial parameters can run either into a de Sitter exponential expansion or into a traversable future soft singularity followed by a contraction phase. We also include in the model (i) a tiny amount of radiation, (ii) baryonic matter (Ω b h 2 = 0.022161, where the Hubble constant is fixed as h = 0.706) and (iii) cold dark matter (CDM). Out of a variety of six types of evolutions arising in a more subtle classification, we identify two in which in the past the scalar field effectively degenerates into a dust (its pressure drops to an insignificantly low negative value). These are the evolutions of type IIb converging to de Sitter and type III hitting the future soft singularity. We confront these background evolutions with various cosmological tests, including the supernova type Ia Union 2.1 data, baryon acoustic oscillation distance ratios, Hubble parameter-redshift relation and the cosmic microwave background (CMB) acoustic scale. We determine a subset of the evolutions of both types which at 1σ confidence level are consistent with all of these cosmological tests. At perturbative level we derive the CMB temperature power spectrum to find the best agreement with the Planck data for Ω CDM = 0.22. The fit is as good as for the ΛCDM model at high multipoles, but the power remains slightly overestimated at low multipoles, for both types of evolutions. The rest of the CDM is effectively generated by the tachyonic field, which in this sense acts as a combined dark energy and dark matter model
The Standardization of Tests: Criteria and Criticisms
Weiner, Paul S.; Hoock, William C.
1973-01-01
Following a review of the procedures involved in the establishment of norms for standardized tests, the specific procedures used to establish norms for three tests commonly used in speech and language pathology are critically examined. (LS)
Searching for signatures of non-standard physics in cosmological surveys
International Nuclear Information System (INIS)
Brunier, Tristan
2006-01-01
This report focuses on the origin of large-scale structures of the universe and the corresponding observable signatures. We examine classical evolution of perturbations before studying quantum mechanism which gave rise to them. The classical evolution of inhomogeneities is described with the theory of cosmological perturbations. Special attention is paid to second-order non-linearities, which are likely to show up tiny effects, set up initially or induced by the evolution. These tools are used to connect the structure of inhomogeneities to that of anisotropies of temperature and polarization of the cosmic microwave background. They allow a new physical interpretation of the power spectra behaviors, including high order effects. The effect induced by a dipolar anisotropy, of statistical or experimental nature, is examined as well as the behavior of non-Gaussian temperature fluctuations of primordial origin. We then explore the properties of quantum fields in curved spacetime, focusing on de Sitter space. In particular, we characterize the consequence of renormalization on the field masses. We finally apply these concepts to quantum fluctuations during inflation. We study the specific signatures of some inflationary models and show that non-Gaussianities are characterized and we check that these models survive radiative corrections to fields masses. (author) [fr
International Nuclear Information System (INIS)
Sasaki, Misao
1983-01-01
We review the recent status of the inflationary cosmology. After exhibiting the essence of difficulties associated with the horizon, flatness and baryon number problems in the standard big-bang cosmology, we discuss that the inflationary universe scenario is one of the most plausible solutions to these fundamental cosmological problems. Since there are two qualitatively different versions of the inflationary universe scenario, we review each of them separately and discuss merits and demerits of each version. The Hawking radiation in de Sitter space is also reviewed since it may play an essential role in the inflationary cosmology. (author)
Direct dark matter searches—Test of the Big Bounce Cosmology
International Nuclear Information System (INIS)
Cheung, Yeuk-Kwan E.; Vergados, J.D.
2015-01-01
We consider the possibility of using dark matter particle's mass and its interaction cross section as a smoking gun signal of the existence of a Big Bounce at the early stage in the evolution of our currently observed universe. A study of dark matter production in the pre-bounce contraction and the post bounce expansion epochs of this universe reveals a new venue for achieving the observed relic abundance of our present universe. Specifically, it predicts a characteristic relation governing a dark matter mass and interaction cross section and a factor of 1/2 in thermally averaged cross section, as compared to the non-thermal production in standard cosmology, is needed for creating enough dark matter particle to satisfy the currently observed relic abundance because dark matter is being created during the pre-bounce contraction, in addition to the post-bounce expansion. As the production rate is lower than the Hubble expansion rate information of the bounce universe evolution is preserved. Therefore once the value of dark matter mass and interaction cross section are obtained by direct detection in laboratories, this alternative route becomes a signature prediction of the bounce universe scenario. This leads us to consider a scalar dark matter candidate, which if it is light, has important implications on dark matter searches
Standard leach tests for nuclear waste materials
International Nuclear Information System (INIS)
Strachan, D.M.; Barnes, B.O.; Turcotte, R.P.
1980-01-01
Five leach tests were conducted to study time-dependent leaching of waste forms (glass). The first four tests include temperature as a variable and the use of three standard leachants. Three of the tests are static and two are dynamic (flow). This paper discusses the waste-form leach tests and presents some representative data. 4 figures
Conformal cosmological model and SNe Ia data
International Nuclear Information System (INIS)
Zakharov, A. F.; Pervushin, V. N.
2012-01-01
Now there is a huge scientific activity in astrophysical studies and cosmological ones in particular. Cosmology transforms from a pure theoretical branch of science into an observational one. All the cosmological models have to pass observational tests. The supernovae type Ia (SNe Ia) test is among the most important ones. If one applies the test to determine parameters of the standard Friedmann-Robertson-Walker cosmological model one can conclude that observations lead to the discovery of the dominance of the Λ term and as a result to an acceleration of the Universe. However, there are big mysteries connected with an origin and an essence of dark matter (DM) and the Λ term or dark energy (DE). Alternative theories of gravitation are treated as a possible solution of DM and DE puzzles. The conformal cosmological approach is one of possible alternatives to the standard ΛCDM model. As it was noted several years ago, in the framework of the conformal cosmological approach an introduction of a rigid matter can explain observational data without Λ term (or dark energy). We confirm the claim with much larger set of observational data.
International Nuclear Information System (INIS)
Partridge, R.B.
1977-01-01
Some sixty years after the development of relativistic cosmology by Einstein and his colleagues, observations are finally beginning to have an important impact on our views of the Universe. The available evidence seems to support one of the simplest cosmological models, the hot Big Bang model. The aim of this paper is to assess the observational support for certain assumptions underlying the hot Big Bang model. These are that the Universe is isobaric and homogeneous on a large scale; that it is expanding from an initial state of high density and temperature; and that the proper theory to describe the dynamics of the Universe is unmodified General Relativity. The properties of the cosmic microwave background radiation and recent observations of the abundance of light elements, in particular, support these assumptions. Also examined here are the data bearing on the related questions of the geometry and the future of the Universe (is it ever-expanding, or fated to recollapse). Finally, some difficulties and faults of the standard model are discussed, particularly various aspects of the 'initial condition' problem. It appears that the simplest Big Bang cosmological model calls for a highly specific set of initial conditions to produce the presently observed properties of the Universe. (Auth.)
International Nuclear Information System (INIS)
Wainwright, J.
1990-01-01
The workshop on mathematical cosmology was devoted to four topics of current interest. This report contains a brief discussion of the historical background of each topic and a concise summary of the content of each talk. The topics were; the observational cosmology program, the cosmological perturbation program, isotropic singularities, and the evolution of Bianchi cosmologies. (author)
International Nuclear Information System (INIS)
Raychaudhuri, A.K.
1979-01-01
The subject is covered in chapters, entitled; introduction; Newtonian gravitation and cosmology; general relativity and relativistic cosmology; analysis of observational data; relativistic models not obeying the cosmological principle; microwave radiation background; thermal history of the universe and nucleosynthesis; singularity of cosmological models; gravitational constant as a field variable; cosmological models based on Einstein-Cartan theory; cosmological singularity in two recent theories; fate of perturbations of isotropic universes; formation of galaxies; baryon symmetric cosmology; assorted topics (including extragalactic radio sources; Mach principle). (U.K.)
Wallace, Colin S.; Prather, Edward E.; Duncan, Douglas K.
2011-01-01
This is the second of five papers detailing our national study of general education astronomy students' conceptual and reasoning difficulties with cosmology. This article begins our quantitative investigation of the data. We describe how we scored students' responses to four conceptual cosmology surveys, and we present evidence for the inter-rater…
The cosmological principle is not in the sky
Park, Chan-Gyung; Hyun, Hwasu; Noh, Hyerim; Hwang, Jai-chan
2017-08-01
The homogeneity of matter distribution at large scales, known as the cosmological principle, is a central assumption in the standard cosmological model. The case is testable though, thus no longer needs to be a principle. Here we perform a test for spatial homogeneity using the Sloan Digital Sky Survey Luminous Red Galaxies (LRG) sample by counting galaxies within a specified volume with the radius scale varying up to 300 h-1 Mpc. We directly confront the large-scale structure data with the definition of spatial homogeneity by comparing the averages and dispersions of galaxy number counts with allowed ranges of the random distribution with homogeneity. The LRG sample shows significantly larger dispersions of number counts than the random catalogues up to 300 h-1 Mpc scale, and even the average is located far outside the range allowed in the random distribution; the deviations are statistically impossible to be realized in the random distribution. This implies that the cosmological principle does not hold even at such large scales. The same analysis of mock galaxies derived from the N-body simulation, however, suggests that the LRG sample is consistent with the current paradigm of cosmology, thus the simulation is also not homogeneous in that scale. We conclude that the cosmological principle is neither in the observed sky nor demanded to be there by the standard cosmological world model. This reveals the nature of the cosmological principle adopted in the modern cosmology paradigm, and opens a new field of research in theoretical cosmology.
Cosmology and particle physics
International Nuclear Information System (INIS)
Turner, M.S.
1986-01-01
Progress in cosmology has become linked to progress in elementary particle physics. In these six lectures, the author illustrates the two-way nature of the interplay between these fields by focusing on a few selected topics. In the next section the author reviews the standard cosmology, especially concentrating on primordial nucleosynthesis and discusses how the standard cosmology has been used to place constraints on the properties of various particles. Grand Unification makes two striking predictions: (i) B non-conservation; (ii) the existence of stable, superheavy magnetic monopoles. Both have had great cosmological impact. In the following section the author discusses baryogenesis, the very attractive scenario in which the B,C,CP violating interactions in GUTs provide a dynamical explanation for the predominance of matter over antimatter and the present baryon-to-photon ratio. Monopoles are a cosmological disaster and an astrophysicist's delight. In Section 4 discusses monopoles, cosmology, and astrophysics. In the fourth lecture the author discusses how a very early (t≤10/sup -34/ sec) phase transition associated with spontaneous symmetry breaking (SSB) has the potential to explain a handful of very fundamental cosmological facts, facts which can be accommodated by the standard cosmology, but which are not ''explained'' by it. The fifth lecture is devoted to a discussion of structure formation in the universe
Comparison of test protocols for standard room/corner tests
R. H. White; M. A. Dietenberger; H. Tran; O. Grexa; L. Richardson; K. Sumathipala; M. Janssens
1998-01-01
As part of international efforts to evaluate alternative reaction-to-fire tests, several series of room/comer tests have been conducted. This paper reviews the overall results of related projects in which different test protocols for standard room/corner tests were used. Differences in the test protocols involved two options for the ignition burner scenario and whether...
Standards for educational and psychological testing
2014-01-01
Developed jointly by the American Educational Research Association, American Psychological Association, and the National Council on Measurement in Education, Standards for Educational and Psychological Testing (Revised 2014) addresses professional and technical issues of test development and use in education, psychology, and employment. It includes changes in federal law and measurement trends affecting validity, testing individuals with disabilities or different linguistic backgrounds, and new types of tests, as well as new uses of existing tests.
International Nuclear Information System (INIS)
Wang Xiaomin; Tegmark, Max; Zaldarriaga, Matias
2002-01-01
We perform a detailed analysis of the latest cosmic microwave background (CMB) measurements (including BOOMERaNG, DASI, Maxima and CBI), both alone and jointly with other cosmological data sets involving, e.g., galaxy clustering and the Lyman Alpha Forest. We first address the question of whether the CMB data are internally consistent once calibration and beam uncertainties are taken into account, performing a series of statistical tests. With a few minor caveats, our answer is yes, and we compress all data into a single set of 24 bandpowers with associated covariance matrix and window functions. We then compute joint constraints on the 11 parameters of the 'standard' adiabatic inflationary cosmological model. Our best fit model passes a series of physical consistency checks and agrees with essentially all currently available cosmological data. In addition to sharp constraints on the cosmic matter budget in good agreement with those of the BOOMERaNG, DASI and Maxima teams, we obtain a heaviest neutrino mass range 0.04-4.2 eV and the sharpest constraints to date on gravity waves which (together with preference for a slight red-tilt) favor 'small-field' inflation models
Boeyens, Jan CA
2010-01-01
The composition of the most remote objects brought into view by the Hubble telescope can no longer be reconciled with the nucleogenesis of standard cosmology and the alternative explanation, in terms of the LAMBDA-Cold-Dark-Matter model, has no recognizable chemical basis. A more rational scheme, based on the chemistry and periodicity of atomic matter, opens up an exciting new interpretation of the cosmos in terms of projective geometry and general relativity. The response of atomic structure to environmental pressure predicts non-Doppler cosmical redshifts and equilibrium nucleogenesis by alp
International Nuclear Information System (INIS)
Verde, L.
2011-01-01
This is the summary of two lectures that aim to give an overview of cosmology. I will not try to be toa rigorous in derivations, nor to give a full historical overview. The idea is to provide a 'taste' of cosmology and some of the interesting topics it covers. The standard cosmological model is presented and I highlight the successes of cosmology over the past decade or so. Keys to the development of the standard cosmological model are observations of the cosmic microwave background and of large-scale structure, which are introduced. Inflation and dark energy and the outlook for the future are also discussed. Slides from the lectures are available from the school web site: physicschool.web.cern.ch/PhysicSchool/CLASHEP/CLASHEP2011/. (author)
Verde, L.
2013-06-27
This is the summary of two lectures that aim to give an overview of cosmology. I will not try to be too rigorous in derivations, nor to give a full historical overview. The idea is to provide a "taste" of cosmology and some of the interesting topics it covers. The standard cosmological model is presented and I highlight the successes of cosmology over the past decade or so. Keys to the development of the standard cosmological model are observations of the cosmic microwave background and of large-scale structure, which are introduced. Inflation and dark energy and the outlook for the future are also discussed. Slides from the lectures are available from the school website: physicschool.web.cern.ch/PhysicSchool/CLASHEP/CLASHEP2011/.
76 FR 74078 - Standard Mail Market Test
2011-11-30
... POSTAL REGULATORY COMMISSION [Docket No. MT2011-3; Order No. 998] Standard Mail Market Test AGENCY... Service application for an exemption from the annual revenue limitation that applies to market tests of... limitation in any year during the test of an experimental market dominant product.\\1\\ Pursuant to 39 U.S.C...
International Nuclear Information System (INIS)
Tkachev, Igor
1993-01-01
When the common ground between particle physics, astrophysics and cosmology started to become a developing area, the Institute for Nuclear Research (INR) of the Russian Academy of Sciences had the foresight in 1981 to institute the Baksan Schools on Particles and Cosmology. This now traditional event, held biannually in the Baksan Valley, has gone on to attract international participation. The site is close to the INR Baksan Neutrino Observatory with its underground and surface installations, including the SAGE gallium solar neutrino detector, the Underground Scintillation Telescope, and the 'Carpet' extensive air shower array. Participation is mainly from experimentalists working in non accelerator particle physics and particle astrophysics. The most recent School, held from April 21 to 28, began with an opening address by INR Director V. A. Matveev. J.Frieman reviewed standard big bang cosmology, emphasizing how the recent COBE results and the observations of large scale galaxy clustering fit into a standard cosmology framework. For inflationary cosmology, he showed how different models may be tested through their predictions for large-scale galactic structure and for cosmic microwave background anisotropy. A.Stebbins presented details of the large scale distribution of galaxies which, combined with velocity information and microwave background anisotropy data, provide strong constraints on theories of the origin of primordial inhomogeneities. Inflation requires, and theories of the large scale structure strongly favour the critical value for the cosmic mass density, while, as D.Seckel explained in his lecture on nucleosynthesis and abundances of the light elements, the baryon contribution to this density has to be tens of times smaller. A general review on the observational evidence for dark matter, dark matter particle candidates and the strategy of dark matter searches was given by I. Tkachev, who stressed the gravitational microlensing MACHO
Neutron Sources for Standard-Based Testing
Energy Technology Data Exchange (ETDEWEB)
Radev, Radoslav [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); McLean, Thomas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2014-11-10
The DHS TC Standards and the consensus ANSI Standards use ^{252}Cf as the neutron source for performance testing because its energy spectrum is similar to the ^{235}U and ^{239}Pu fission sources used in nuclear weapons. An emission rate of 20,000 ± 20% neutrons per second is used for testing of the radiological requirements both in the ANSI standards and the TCS. Determination of the accurate neutron emission rate of the test source is important for maintaining consistency and agreement between testing results obtained at different testing facilities. Several characteristics in the manufacture and the decay of the source need to be understood and accounted for in order to make an accurate measurement of the performance of the neutron detection instrument. Additionally, neutron response characteristics of the particular instrument need to be known and taken into account as well as neutron scattering in the testing environment.
Development of the Universe and New Cosmology
Sakharov, Alexander S
2003-01-01
Cosmology is undergoing an explosive period of activity, fueled both by new, accurate astrophysical data and by innovative theoretical developments. Cosmological parameters such as the total density of the Universe and the rate of cosmological expansion are being precisely measured for the first time, and a consistent standard picture of the Universe is beginning to emerge. Recent developments in cosmology give rise the intriguing possibility that all structures in the Universe, from superclusters to planets, had a quantum-mechanical origin in its earliest moments. Furthermore, these ideas are not idle theorizing, but predictive, and subject to meaningful experimental test. We review the concordance model of the development of the Universe, as well as evidence for the observational revolution that this field is going through. This already provides us with important information on particle physics, which is inaccessible to accelerators.
International Nuclear Information System (INIS)
Stecker, F.W.
1989-01-01
This paper discusses two aspects of antimatter and cosmology: 1. the fundamental cosmological question as to whether antimatter plays an equally important role as matter in the universe (overall baryon symmetry), and 2. cosmic-ray antimatter tests for the nature of the dark matter in the universe. (orig.)
Combination and interpretation of observables in Cosmology
Directory of Open Access Journals (Sweden)
Virey Jean-Marc
2010-04-01
Full Text Available The standard cosmological model has deep theoretical foundations but need the introduction of two major unknown components, dark matter and dark energy, to be in agreement with various observations. Dark matter describes a non-relativistic collisionless fluid of (non baryonic matter which amount to 25% of the total density of the universe. Dark energy is a new kind of fluid not of matter type, representing 70% of the total density which should explain the recent acceleration of the expansion of the universe. Alternatively, one can reject this idea of adding one or two new components but argue that the equations used to make the interpretation should be modified consmological scales. Instead of dark matter one can invoke a failure of Newton's laws. Instead of dark energy, two approaches are proposed : general relativity (in term of the Einstein equation should be modified, or the cosmological principle which fixes the metric used for cosmology should be abandonned. One of the main objective of the community is to find the path of the relevant interpretations thanks to the next generation of experiments which should provide large statistics of observationnal data. Unfortunately, cosmological in formations are difficult to pin down directly fromt he measurements, and it is mandatory to combine the various observables to get the cosmological parameters. This is not problematic from the statistical point of view, but assumptions and approximations made for the analysis may bias our interprettion of the data. Consequently, a strong attention should be paied to the statistical methods used to make parameters estimation and for model testing. After a review of the basics of cosmology where the cosmological parameters are introduced, we discuss the various cosmological probes and their associated observables used to extract cosmological informations. We present the results obtained from several statistical analyses combining data of diferent nature but
Standardized Definitions for Code Verification Test Problems
Energy Technology Data Exchange (ETDEWEB)
Doebling, Scott William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2017-09-14
This document contains standardized definitions for several commonly used code verification test problems. These definitions are intended to contain sufficient information to set up the test problem in a computational physics code. These definitions are intended to be used in conjunction with exact solutions to these problems generated using Exact- Pack, www.github.com/lanl/exactpack.
Is the standard model really tested?
International Nuclear Information System (INIS)
Takasugi, E.
1989-01-01
It is discussed how the standard model is really tested. Among various tests, I concentrate on the CP violation phenomena in K and B meson system. Especially, the resent hope to overcome the theoretical uncertainty in the evaluation on the CP violation of K meson system is discussed. (author)
Classical and quantum cosmology
Calcagni, Gianluca
2017-01-01
This comprehensive textbook is devoted to classical and quantum cosmology, with particular emphasis on modern approaches to quantum gravity and string theory and on their observational imprint. It covers major challenges in theoretical physics such as the big bang and the cosmological constant problem. An extensive review of standard cosmology, the cosmic microwave background, inflation and dark energy sets the scene for the phenomenological application of all the main quantum-gravity and string-theory models of cosmology. Born of the author's teaching experience and commitment to bridging the gap between cosmologists and theoreticians working beyond the established laws of particle physics and general relativity, this is a unique text where quantum-gravity approaches and string theory are treated on an equal footing. As well as introducing cosmology to undergraduate and graduate students with its pedagogical presentation and the help of 45 solved exercises, this book, which includes an ambitious bibliography...
Energy Technology Data Exchange (ETDEWEB)
Avgoustidis, Anastasios [Centre for Theoretical Cosmology, DAMTP, CMS, Wilberforce Road, Cambridge CB3 0WA (United Kingdom); Burrage, Clare [Deutsches Elektronen Synchrotron DESY, Notkestrasse 85, D-22607 Hamburg (Germany); Redondo, Javier [Max Planck Institut für Physik, Föhringer Ring 6, D-80805, Munich (Germany); Verde, Licia; Jimenez, Raul, E-mail: a.avgoustidis@damtp.cam.ac.uk, E-mail: clare.burrage@desy.de, E-mail: redondo@mppmu.mpg.de, E-mail: liciaverde@icc.ub.edu, E-mail: raul.jimenez@icc.ub.edu [ICREA and Institute for Sciences of the Cosmos (ICC), University of Barcelona, IEEC, Barcelona 08028 (Spain)
2010-10-01
We update constraints on cosmic opacity by combining recent SN Type Ia data with the latest measurements of the Hubble expansion at redshifts between 0 and 2. The new constraint on the parameter ε parametrising deviations from the luminosity-angular diameter distance relation (d{sub L} = d{sub A}(1+z){sup 2+ε}), is ε = −0.04{sub −0.07}{sup +0.08} (2-σ). For the redshift range between 0.2 and 0.35 this corresponds to an opacity Δτ < 0.012 (95% C.L.), a factor of 2 stronger than the previous constraint. Various models of beyond the standard model physics that predict violation of photon number conservation contribute to the opacity and can be equally constrained. In this paper we put new limits on axion-like particles, including chameleons, and mini-charged particles.
Energy Technology Data Exchange (ETDEWEB)
Avgoustidis, Anastasios [DAMTP, CMS, Cambridge (United Kingdom). Centre for Theoretical Cosmology; Burrage, Clare [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Redondo, Javier [Max-Planck-Institut fuer Physik, Munich (Germany); Verde, Licia; Jimenez, Raul [Barcelona Univ., IEEC (ES). ICREA and Inst. for Sciences of the Cosmos (ICC)
2010-04-15
We update constraints on cosmic opacity by combining recent SN Type Ia data compilation with the latest measurements of the Hubble expansion at redshifts between 0 and 2. The new constraint on the parameter {epsilon} parametrising deviations from the luminosity-angular diameter distance relation (d{sub L}=d{sub A}(1+z){sup 2+{epsilon}}), is {epsilon}=-0.04{sub -0.07}{sup +0.08} (2-{sigma}). For the redshift range between 0.2 and 0.35 this corresponds to an opacity {delta}{tau}<0.012 (95% C.L.), a factor of 2 stronger than the previous constraint. Various models of beyond the standard model physics that predict violation of photon number conservation contribute to the opacity and can be equally constrained. In this paper we put new limits on axion-like particles, including chameleons, and minicharged particles. (orig.)
International Nuclear Information System (INIS)
Avgoustidis, Anastasios; Redondo, Javier; Verde, Licia; Jimenez, Raul
2010-04-01
We update constraints on cosmic opacity by combining recent SN Type Ia data compilation with the latest measurements of the Hubble expansion at redshifts between 0 and 2. The new constraint on the parameter ε parametrising deviations from the luminosity-angular diameter distance relation (d L =d A (1+z) 2+ε ), is ε=-0.04 -0.07 +0.08 (2-σ). For the redshift range between 0.2 and 0.35 this corresponds to an opacity Δτ<0.012 (95% C.L.), a factor of 2 stronger than the previous constraint. Various models of beyond the standard model physics that predict violation of photon number conservation contribute to the opacity and can be equally constrained. In this paper we put new limits on axion-like particles, including chameleons, and minicharged particles. (orig.)
International Nuclear Information System (INIS)
Landsberg, P.T.; Evans, D.A.
1977-01-01
The subject is dealt with in chapters, entitled: cosmology -some fundamentals; Newtonian gravitation - some fundamentals; the cosmological differential equation - the particle model and the continuum model; some simple Friedmann models; the classification of the Friedmann models; the steady-state model; universe with pressure; optical effects of the expansion according to various theories of light; optical observations and cosmological models. (U.K.)
Nondestructive testing standards and the ASME code
International Nuclear Information System (INIS)
Spanner, J.C.
1991-04-01
Nondestructive testing (NDT) requirements and standards are an important part of the ASME Boiler and Pressure Vessel Code. In this paper, the evolution of these requirements and standards is reviewed in the context of the unique technical and legal stature of the ASME Code. The coherent and consistent manner by which the ASME Code rules are organized is described, and the interrelationship between the various ASME Code sections, the piping codes, and the ASTM Standards is discussed. Significant changes occurred in ASME Sections 5 and 11 during the 1980s, and these are highlighted along with projections and comments regarding future trends and changes in these important documents. 4 refs., 8 tabs
Post-inflationary brane cosmology
International Nuclear Information System (INIS)
Mazumdar, Anupam
2001-01-01
The brane cosmology has invoked new challenges to the usual Big Bang cosmology. In this paper we present a brief account on thermal history of the post-inflationary brane cosmology. We have realized that it is not obvious that the post-inflationary brane cosmology would always deviate from the standard Big Bang cosmology. However, if it deviates some stringent conditions on the brane tension are to be satisfied. In this regard we study various implications on gravitino production and its abundance. We discuss Affleck-Dine mechanism for baryogenesis and make some comments on moduli and dilaton problems in this context
Observable cosmology and cosmological models
International Nuclear Information System (INIS)
Kardashev, N.S.; Lukash, V.N.; Novikov, I.D.
1987-01-01
Modern state of observation cosmology is briefly discussed. Among other things, a problem, related to Hibble constant and slowdown constant determining is considered. Within ''pancake'' theory hot (neutrino) cosmological model explains well the large-scale structure of the Universe, but does not explain the galaxy formation. A cold cosmological model explains well light object formation, but contradicts data on large-scale structure
The skin prick test – European standards
Directory of Open Access Journals (Sweden)
Heinzerling Lucie
2013-02-01
Full Text Available Abstract Skin prick testing is an essential test procedure to confirm sensitization in IgE-mediated allergic disease in subjects with rhinoconjunctivitis, asthma, urticaria, anapylaxis, atopic eczema and food and drug allergy. This manuscript reviews the available evidence including Medline and Embase searches, abstracts of international allergy meetings and position papers from the world allergy literature. The recommended method of prick testing includes the appropriate use of specific allergen extracts, positive and negative controls, interpretation of the tests after 15 – 20 minutes of application, with a positive result defined as a wheal ≥3 mm diameter. A standard prick test panel for Europe for inhalants is proposed and includes hazel (Corylus avellana, alder (Alnus incana, birch (Betula alba, plane (Platanus vulgaris, cypress (Cupressus sempervirens, grass mix (Poa pratensis, Dactilis glomerata, Lolium perenne, Phleum pratense, Festuca pratensis, Helictotrichon pretense, Olive (Olea europaea, mugwort (Artemisia vulgaris, ragweed (Ambrosia artemisiifolia, Alternaria alternata (tenuis, Cladosporium herbarum, Aspergillus fumigatus, Parietaria, cat, dog, Dermatophagoides pteronyssinus, Dermatophagoides farinae, and cockroach (Blatella germanica. Standardization of the skin test procedures and standard panels for different geographic locations are encouraged worldwide to permit better comparisons for diagnostic, clinical and research purposes.
Neutrino properties from cosmology
DEFF Research Database (Denmark)
Hannestad, S.
2013-01-01
In recent years precision cosmology has become an increasingly powerful probe of particle physics. Perhaps the prime example of this is the very stringent cosmological upper bound on the neutrino mass. However, other aspects of neutrino physics, such as their decoupling history and possible non......-standard interactions, can also be probed using observations of cosmic structure. Here, I review the current status of cosmological bounds on neutrino properties and discuss the potential of future observations, for example by the recently approved EUCLID mission, to precisely measure neutrino properties....
Zhang Yuan Zhong
2002-01-01
This book is one of a series in the areas of high-energy physics, cosmology and gravitation published by the Institute of Physics. It includes courses given at a doctoral school on 'Relativistic Cosmology: Theory and Observation' held in Spring 2000 at the Centre for Scientific Culture 'Alessandro Volta', Italy, sponsored by SIGRAV-Societa Italiana di Relativita e Gravitazione (Italian Society of Relativity and Gravitation) and the University of Insubria. This book collects 15 review reports given by a number of outstanding scientists. They touch upon the main aspects of modern cosmology from observational matters to theoretical models, such as cosmological models, the early universe, dark matter and dark energy, modern observational cosmology, cosmic microwave background, gravitational lensing, and numerical simulations in cosmology. In particular, the introduction to the basics of cosmology includes the basic equations, covariant and tetrad descriptions, Friedmann models, observation and horizons, etc. The ...
Precision tests of the Standard Model
International Nuclear Information System (INIS)
Ol'shevskij, A.G.
1996-01-01
The present status of the precision measurements of electroweak observables is discussed with the special emphasis on the results obtained recently. All together these measurements provide the basis for the stringent test of the Standard Model and determination of the SM parameters. 22 refs., 23 figs., 11 tabs
International Nuclear Information System (INIS)
Turner, Michael S.
1999-01-01
For two decades the hot big-bang model as been referred to as the standard cosmology - and for good reason. For just as long cosmologists have known that there are fundamental questions that are not answered by the standard cosmology and point to a grander theory. The best candidate for that grander theory is inflation + cold dark matter. It holds that the Universe is flat, that slowly moving elementary particles left over from the earliest moments provide the cosmic infrastructure, and that the primeval density inhomogeneities that seed all the structure arose from quantum fluctuations. There is now prima facie evidence that supports two basic tenets of this paradigm. An avalanche of high-quality cosmological observations will soon make this case stronger or will break it. Key questions remain to be answered; foremost among them are: identification and detection of the cold dark matter particles and elucidation of the dark-energy component. These are exciting times in cosmology!
Antiproton interaction with 4He as a test of GUT cosmology
International Nuclear Information System (INIS)
Chechetkin, V.M.; Khlopov, M.Yu.; Zeldovich, Ya.B.
1982-01-01
A new possibility of checking some GUT models is suggested, basing on the analysis of their cosmological consequences and the experimental study of the anti p 4 He interaction. The study of annihilation of antiprotons with 4 He may provide limits on the possible amount of antimatter in the early Universe, limits on the probability of formation of primordial black holes and restrictions on the GUT parameters determining the properties of domains of antimatter
Standard specification for agencies performing nondestructive testing
American Society for Testing and Materials. Philadelphia
2009-01-01
1.1 This specification covers minimum requirements for agencies performing nondestructive testing (NDT). 1.2 When using this specification to assess the capability of, or to accredit NDT agencies, Guide E 1359 shall be used as a basis for the survey. It can be supplemented as necessary with more detail in order to meet the auditor's specific needs. 1.3 This specification can be used as a basis to evaluate testing or inspection agencies, or both, and is intended for use for the qualifying or accrediting, or both, of testing or inspection agencies, public or private. 1.4 The use of SI or inch-pound units, or combination thereof, will be the responsibility of the technical committee whose standards are referred to in this standard. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to...
Patch testing with Indian standard series
Directory of Open Access Journals (Sweden)
Narendra G
2002-01-01
Full Text Available Hundred patients (61 males, 39 females suspected to have allergic contact dermatitis were patch tested with Indian standard series (ISS. Forty four showed one or more positive reactions. The frequent sensitizers observed were nickel sulphate-12 (15%, potassium dichromate-11 (13.75%, cobalt chloride and colophony-7 (8.75% each, fragrance mix and thiuram mix-6 (7.5% each. The ISS differs from the European Standard Series by inclusion of propylene glycol, nitrofurazone, gentamicin, chlorocresol, PEG-400 and ethylenediamine chloride where assesquiterpene lactone mix and primin allergens are excluded.
Seminar on standards, standardization, quality control and interlaboratory test programmes
Energy Technology Data Exchange (ETDEWEB)
de Bievre, P. [Central Bureau for Nuclear Measurements, Geel (Belgium)
1978-12-15
The author gives a resume on the proper use of standards and standardization of measurement procedures. Results of measurements obtained on the same instrument and on the same series of standards of different isotopic compositions are displayed.
International Nuclear Information System (INIS)
Valotti, Andrea
2016-01-01
Cosmology is one of the fundamental pillars of astrophysics, as such it contains many unsolved puzzles. To investigate some of those puzzles, we analyze X-ray surveys of galaxy clusters. These surveys are possible thanks to the bremsstrahlung emission of the intra-cluster medium. The simultaneous fit of cluster counts as a function of mass and distance provides an independent measure of cosmological parameters such as Ω m , σ s , and the dark energy equation of state w0. A novel approach to cosmological analysis using galaxy cluster data, called top-down, was developed in N. Clerc et al. (2012). This top-down approach is based purely on instrumental observables that are considered in a two-dimensional X-ray color-magnitude diagram. The method self-consistently includes selection effects and scaling relationships. It also provides a means of bypassing the computation of individual cluster masses. My work presents an extension of the top-down method by introducing the apparent size of the cluster, creating a three-dimensional X-ray cluster diagram. The size of a cluster is sensitive to both the cluster mass and its angular diameter, so it must also be included in the assessment of selection effects. The performance of this new method is investigated using a Fisher analysis. In parallel, I have studied the effects of the intrinsic scatter in the cluster size scaling relation on the sample selection as well as on the obtained cosmological parameters. To validate the method, I estimate uncertainties of cosmological parameters with MCMC method Amoeba minimization routine and using two simulated XMM surveys that have an increasing level of complexity. The first simulated survey is a set of toy catalogues of 100 and 10000 deg 2 , whereas the second is a 1000 deg 2 catalogue that was generated using an Aardvark semi-analytical N-body simulation. This comparison corroborates the conclusions of the Fisher analysis. In conclusion, I find that a cluster diagram that accounts
Primordial alchemy: a test of the standard model
International Nuclear Information System (INIS)
Steigman, G.
1987-01-01
Big Bang Nucleosynthesis provides the only probe of the early evolution of the Universe constrained by observational data. The standard, hot, big bang model predicts the synthesis of the light elements (D, 3 He, 4 He, 7 Li) in astrophysically interesting abundances during the first few minutes in the evolution of the Universe. A quantitative comparison of the predicted abundances with those observed astronomically confirms the consistency of the standard model and yields valuable constraints on the parameters of cosmology and elementary particle physics. The current status of the comparison between theory and observation will be reviewed and the opportunities for future advances outlined
Cosmological Reflection of Particle Symmetry
Directory of Open Access Journals (Sweden)
Maxim Khlopov
2016-08-01
Full Text Available The standard model involves particle symmetry and the mechanism of its breaking. Modern cosmology is based on inflationary models with baryosynthesis and dark matter/energy, which involves physics beyond the standard model. Studies of the physical basis of modern cosmology combine direct searches for new physics at accelerators with its indirect non-accelerator probes, in which cosmological consequences of particle models play an important role. The cosmological reflection of particle symmetry and the mechanisms of its breaking are the subject of the present review.
Standardization of penetrating radiation testing system
International Nuclear Information System (INIS)
Wiley, P.A.; Aronson, H.L.
1979-01-01
Standardization is provided to control system gain of a penetrating radiation testing system by periodically inspecting a reference object in the same manner as the product samples so as to generate a stabilization signal which is compared to a reference signal. The difference, if any, between the stabilization signal and the reference signal is integrated and the integrated signal is used to correct the gain of the system
Standardization of Tests for Advanced Composites
石川, 隆司; ISHIKAWA, Takashi; 野口, 義男; NOGUCHI, Yoshio; 濱口, 泰正; HAMAGUCHI, Yasumasa
2003-01-01
Advanced composites are essentially the only feasible materials for the construction of newly developed aerospace vehicle. However, the path to be followed for the validation, evaluation and certification of composite aircraft structures is quite different from that of traditional metallic aircraft structures, and the importance of a composites database is now well recognized. A key issue in constructing a fully descriptive composites database is to establish standard composite test methods, ...
Standard test method for dynamic tear testing of metallic materials
American Society for Testing and Materials. Philadelphia
1983-01-01
1.1 This test method covers the dynamic tear (DT) test using specimens that are 3/16 in. to 5/8 in. (5 mm to 16 mm) inclusive in thickness. 1.2 This test method is applicable to materials with a minimum thickness of 3/16 in. (5 mm). 1.3 The pressed-knife procedure described for sharpening the notch tip generally limits this test method to materials with a hardness level less than 36 HRC. Note 1—The designation 36 HRC is a Rockwell hardness number of 36 on Rockwell C scale as defined in Test Methods E 18. 1.4 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
Axion cold dark matter in nonstandard cosmologies
International Nuclear Information System (INIS)
Visinelli, Luca; Gondolo, Paolo
2010-01-01
We study the parameter space of cold dark matter axions in two cosmological scenarios with nonstandard thermal histories before big bang nucleosynthesis: the low-temperature reheating (LTR) cosmology and the kination cosmology. If the Peccei-Quinn symmetry breaks during inflation, we find more allowed parameter space in the LTR cosmology than in the standard cosmology and less in the kination cosmology. On the contrary, if the Peccei-Quinn symmetry breaks after inflation, the Peccei-Quinn scale is orders of magnitude higher than standard in the LTR cosmology and lower in the kination cosmology. We show that the axion velocity dispersion may be used to distinguish some of these nonstandard cosmologies. Thus, axion cold dark matter may be a good probe of the history of the Universe before big bang nucleosynthesis.
Testing Gravity on Cosmological Scales with the Observed Abundance of Galaxy Clusters
DEFF Research Database (Denmark)
Rapetti Serra, David Angelo
2011-01-01
supernovae, baryon acoustic oscillations, and cosmic microwave background data we find a tight correlation between the growth index and the normalization of the matter power spectrum. Allowing the growth index and the dark energy equation of state parameter to take any constant values, we find no evidence......, and obtain improved constraints on departures from General Relativity (GR) on cosmological scales. We parameterize the linear growth rate of cosmic structure with a power law of the mean matter density to the growth index. Combining the X-ray cluster growth data with cluster gas-mass fraction, type Ia...
Cosmological Models and Stability
Andersson, Lars
Principles in the form of heuristic guidelines or generally accepted dogma play an important role in the development of physical theories. In particular, philosophical considerations and principles figure prominently in the work of Albert Einstein. As mentioned in the talk by Jiří Bičák at this conference, Einstein formulated the equivalence principle, an essential step on the road to general relativity, during his time in Prague 1911-1912. In this talk, I would like to discuss some aspects of cosmological models. As cosmology is an area of physics where "principles" such as the "cosmological principle" or the "Copernican principle" play a prominent role in motivating the class of models which form part of the current standard model, I will start by comparing the role of the equivalence principle to that of the principles used in cosmology. I will then briefly describe the standard model of cosmology to give a perspective on some mathematical problems and conjectures on cosmological models, which are discussed in the later part of this paper.
Cosmology for high energy physicists
International Nuclear Information System (INIS)
Albrecht, A.
1987-11-01
The standard big bang model of cosmology is presented. Although not perfect, its many successes make it a good starting point for most discussions of cosmology. Places are indicated where well understood laboratory physics is incorporated into the big bang, leading to successful predictions. Much less established aspects of high energy physics and some of the new ideas they have introduced into the field of cosmology are discussed, such as string theory, inflation and monopoles. 49 refs., 5 figs
Consistency test of the standard model
International Nuclear Information System (INIS)
Pawlowski, M.; Raczka, R.
1997-01-01
If the 'Higgs mass' is not the physical mass of a real particle but rather an effective ultraviolet cutoff then a process energy dependence of this cutoff must be admitted. Precision data from at least two energy scale experimental points are necessary to test this hypothesis. The first set of precision data is provided by the Z-boson peak experiments. We argue that the second set can be given by 10-20 GeV e + e - colliders. We pay attention to the special role of tau polarization experiments that can be sensitive to the 'Higgs mass' for a sample of ∼ 10 8 produced tau pairs. We argue that such a study may be regarded as a negative selfconsistency test of the Standard Model and of most of its extensions
Standard-E hydrogen monitoring system shop acceptance test procedure
Energy Technology Data Exchange (ETDEWEB)
Schneider, T.C.
1997-10-02
The purpose of this report is to document that the Standard-E Hydrogen Monitoring Systems (SHMS-E), fabricated by Mid-Columbia Engineering (MCE) for installation on the Waste Tank Farms in the Hanford 200 Areas, are constructed as intended by the design. The ATP performance will verify proper system fabrication.
Standard-E hydrogen monitoring system shop acceptance test report
International Nuclear Information System (INIS)
Schneider, T.C.
1997-01-01
The purpose of this report is to document that the Standard-E Hydrogen Monitoring Systems (SHMS-E), fabricated by Mid-Columbia Engineering (MCE) for installation on the Waste Tank Farms in the Hanford 200 Areas, are constructed as intended by the design. The ATP performance will verify proper system fabrication
Standard practice for instrumented indentation testing
American Society for Testing and Materials. Philadelphia
2007-01-01
1.1 This practice defines the basic steps of Instrumented Indentation Testing (IIT) and establishes the requirements, accuracies, and capabilities needed by an instrument to successfully perform the test and produce the data that can be used for the determination of indentation hardness and other material characteristics. IIT is a mechanical test that measures the response of a material to the imposed stress and strain of a shaped indenter by forcing the indenter into a material and monitoring the force on, and displacement of, the indenter as a function of time during the full loading-unloading test cycle. 1.2 The operational features of an IIT instrument, as well as requirements for Instrument Verification Annex A1), Standardized Reference Blocks (Annex A2) and Indenter Requirements (Annex A3) are defined. This practice is not intended to be a complete purchase specification for an IIT instrument. 1.3 With the exception of the non-mandatory Appendix X4, this practice does not define the analysis necessary...
Cosmological Probes for Supersymmetry
Directory of Open Access Journals (Sweden)
Maxim Khlopov
2015-05-01
Full Text Available The multi-parameter character of supersymmetric dark-matter models implies the combination of their experimental studies with astrophysical and cosmological probes. The physics of the early Universe provides nontrivial effects of non-equilibrium particles and primordial cosmological structures. Primordial black holes (PBHs are a profound signature of such structures that may arise as a cosmological consequence of supersymmetric (SUSY models. SUSY-based mechanisms of baryosynthesis can lead to the possibility of antimatter domains in a baryon asymmetric Universe. In the context of cosmoparticle physics, which studies the fundamental relationship of the micro- and macro-worlds, the development of SUSY illustrates the main principles of this approach, as the physical basis of the modern cosmology provides cross-disciplinary tests in physical and astronomical studies.
Tensors, relativity, and cosmology
Dalarsson, Mirjana
2015-01-01
Tensors, Relativity, and Cosmology, Second Edition, combines relativity, astrophysics, and cosmology in a single volume, providing a simplified introduction to each subject that is followed by detailed mathematical derivations. The book includes a section on general relativity that gives the case for a curved space-time, presents the mathematical background (tensor calculus, Riemannian geometry), discusses the Einstein equation and its solutions (including black holes and Penrose processes), and considers the energy-momentum tensor for various solutions. In addition, a section on relativistic astrophysics discusses stellar contraction and collapse, neutron stars and their equations of state, black holes, and accretion onto collapsed objects, with a final section on cosmology discussing cosmological models, observational tests, and scenarios for the early universe. This fully revised and updated second edition includes new material on relativistic effects, such as the behavior of clocks and measuring rods in m...
Testing cosmology from fundamental considerations: Is the Friedmann universe intrinsically flat
Mitra, Abhas
2014-02-01
Recently Melia and Shevchuk (Mon Not R Astron Soc 419:2579,2012) (MS) have proposed the so-called cosmology where the "Gravitational Horizon" of the universe is equal to the distance travelled by light since "Big Bang". Here we would like to see whether the basic claim is correct or not because MS have not given any cogent derivation for the same. Essentially we will compare the twin expressions for the Einstein energy momentum complex (EMC) of the Friedmann universe obtained by using an appropriate superpotential and also by a direct method. To enable a meaningful comparison of the twin expressions, both are computed by using the same quasi-Cartesian coordinates. We however do not claim that Einstein EMC is superior to many other routes of defining EM of a self-gravitating system. In fact, for static isolated spherical syatems, the idea of a coordinate independent field energy of Lynden-Bell and Katz (Mon Not R Astron Soc 213:21, 1985) might be quite physically significant. Yet, here, we use Einstein EMC because (i) our system is non-static and not isolated one (ii) our primary aim is not find any absolute value of EM, and, finally, (iii) only Einstein pseudo-tensor offers equivalent twin expressions for EM which one can be equated irrespective of any physical significance. Following such comparison of equivalent twin expressions of Einstein energy, we find an exact proof as to why Friedmann universe must be spatially flat even though, mathematically one can conceive of curved spaces in any dimension. Additionally, it follows that, apparently, the scale factor as insisted by proposition. Nonetheless, because of close similarity of this form, , with the (vacuum) Milne metric, and also because of implied unphysical equation of state, cosmology is unlikely to represent the physical universe.
Producing a scale-invariant spectrum of perturbations in a Hagedorn phase of string cosmology.
Nayeri, Ali; Brandenberger, Robert H; Vafa, Cumrun
2006-07-14
We study the generation of cosmological perturbations during the Hagedorn phase of string gas cosmology. Using tools of string thermodynamics we provide indications that it may be possible to obtain a nearly scale-invariant spectrum of cosmological fluctuations on scales which are of cosmological interest today. In our cosmological scenario, the early Hagedorn phase of string gas cosmology goes over smoothly into the radiation-dominated phase of standard cosmology, without having a period of cosmological inflation.
International Nuclear Information System (INIS)
Leibundgut, B.
2005-01-01
Supernovae have developed into a versatile tool for cosmology. Their impact on the cosmological model has been profound and led to the discovery of the accelerated expansion. The current status of the cosmological model as perceived through supernova observations will be presented. Supernovae are currently the only astrophysical objects that can measure the dynamics of the cosmic expansion during the past eight billion years. Ongoing experiments are trying to determine the characteristics of the accelerated expansion and give insight into what might be the physical explanation for the acceleration. (author)
International Nuclear Information System (INIS)
Meng Xiaolei; Zhang Tongjie; Zhan Hu; Wang Xin
2012-01-01
Aiming at comparing different morphological models of galaxy clusters, we use two new methods to make a cosmological model-independent test of the distance-duality (DD) relation. The luminosity distances come from the Union2 compilation of Supernovae Type Ia. The angular diameter distances are given by two cluster models (De Filippis et al. and Bonamente et al.). The advantage of our methods is that they can reduce statistical errors. Concerning the morphological hypotheses for cluster models, it is mainly focused on the comparison between the elliptical β-model and spherical β-model. The spherical β-model is divided into two groups in terms of different reduction methods of angular diameter distances, i.e., the conservative spherical β-model and corrected spherical β-model. Our results show that the DD relation is consistent with the elliptical β-model at 1σ confidence level (CL) for both methods, whereas for almost all spherical β-model parameterizations, the DD relation can only be accommodated at 3σ CL, particularly for the conservative spherical β-model. In order to minimize systematic uncertainties, we also apply the test to the overlap sample, i.e., the same set of clusters modeled by both De Filippis et al. and Bonamente et al. It is found that the DD relation is compatible with the elliptically modeled overlap sample at 1σ CL; however, for most of the parameterizations the DD relation cannot be accommodated even at 3σ CL for any of the two spherical β-models. Therefore, it is reasonable that the marked triaxial ellipsoidal model is a better geometrical hypothesis describing the structure of the galaxy cluster compared with the spherical β-model if the DD relation is valid in cosmological observations.
Experimental tests of the standard model
International Nuclear Information System (INIS)
Nodulman, L.
1998-01-01
The title implies an impossibly broad field, as the Standard Model includes the fermion matter states, as well as the forces and fields of SU(3) x SU(2) x U(1). For practical purposes, I will confine myself to electroweak unification, as discussed in the lectures of M. Herrero. Quarks and mixing were discussed in the lectures of R. Aleksan, and leptons and mixing were discussed in the lectures of K. Nakamura. I will essentially assume universality, that is flavor independence, rather than discussing tests of it. I will not pursue tests of QED beyond noting the consistency and precision of measurements of α EM in various processes including the Lamb shift, the anomalous magnetic moment (g-2) of the electron, and the quantum Hall effect. The fantastic precision and agreement of these predictions and measurements is something that convinces people that there may be something to this science enterprise. Also impressive is the success of the ''Universal Fermi Interaction'' description of beta decay processes, or in more modern parlance, weak charged current interactions. With one coupling constant G F , most precisely determined in muon decay, a huge number of nuclear instabilities are described. The slightly slow rate for neutron beta decay was one of the initial pieces of evidence for Cabbibo mixing, now generalized so that all charged current decays of any flavor are covered
International Nuclear Information System (INIS)
Berstein, J.
1984-01-01
These lectures offer a self-contained review of the role of neutrinos in cosmology. The first part deals with the question 'What is a neutrino.' and describes in a historical context the theoretical ideas and experimental discoveries related to the different types of neutrinos and their properties. The basic differences between the Dirac neutrino and the Majorana neutrino are pointed out and the evidence for different neutrino 'flavours', neutrino mass, and neutrino oscillations is discussed. The second part summarizes current views on cosmology, particularly as they are affected by recent theoretical and experimental advances in high-energy particle physics. Finally, the close relationship between neutrino physics and cosmology is brought out in more detail, to show how cosmological constraints can limit the various theoretical possibilities for neutrinos and, more particularly, how increasing knowledge of neutrino properties can contribute to our understanding of the origin, history, and future of the Universe. The level is that of the beginning graduate student. (orig.)
International Nuclear Information System (INIS)
Khalatnikov, I.M.; Belinskij, V.A.
1984-01-01
Application of the qualitative theory of dynamic systems to analysis of homogeneous cosmological models is described. Together with the well-known cases, requiring ideal liquid, the properties of cosmological evolution of matter with dissipative processes due to viscosity are considered. New cosmological effects occur, when viscosity terms being one and the same order with the rest terms in the equations of gravitation or even exceeding them. In these cases the description of the dissipative process by means of only two viscosity coefficients (volume and shift) may become inapplicable because all the rest decomposition terms of dissipative addition to the energy-momentum in velocity gradient can be large application of equations with hydrodynamic viscosty should be considered as a model of dissipative effects in cosmology
International Nuclear Information System (INIS)
Zeldovich, Y.B.
1983-01-01
This paper fives a general review of modern cosmology. The following subjects are discussed: hot big bang and periodization of the evolution; Hubble expansion; the structure of the universe (pancake theory); baryon asymmetry; inflatory universe. (Auth.)
Energy Technology Data Exchange (ETDEWEB)
Zhang Yuanzhong
2002-06-21
This book is one of a series in the areas of high-energy physics, cosmology and gravitation published by the Institute of Physics. It includes courses given at a doctoral school on 'Relativistic Cosmology: Theory and Observation' held in Spring 2000 at the Centre for Scientific Culture 'Alessandro Volta', Italy, sponsored by SIGRAV-Societa Italiana di Relativita e Gravitazione (Italian Society of Relativity and Gravitation) and the University of Insubria. This book collects 15 review reports given by a number of outstanding scientists. They touch upon the main aspects of modern cosmology from observational matters to theoretical models, such as cosmological models, the early universe, dark matter and dark energy, modern observational cosmology, cosmic microwave background, gravitational lensing, and numerical simulations in cosmology. In particular, the introduction to the basics of cosmology includes the basic equations, covariant and tetrad descriptions, Friedmann models, observation and horizons, etc. The chapters on the early universe involve inflationary theories, particle physics in the early universe, and the creation of matter in the universe. The chapters on dark matter (DM) deal with experimental evidence of DM, neutrino oscillations, DM candidates in supersymmetry models and supergravity, structure formation in the universe, dark-matter search with innovative techniques, and dark energy (cosmological constant), etc. The chapters about structure in the universe consist of the basis for structure formation, quantifying large-scale structure, cosmic background fluctuation, galaxy space distribution, and the clustering of galaxies. In the field of modern observational cosmology, galaxy surveys and cluster surveys are given. The chapter on gravitational lensing describes the lens basics and models, galactic microlensing and galaxy clusters as lenses. The last chapter, 'Numerical simulations in cosmology', deals with spatial and
International Nuclear Information System (INIS)
Zeldovich, Ya.
1984-01-01
The knowledge is summed up of contemporary cosmology on the universe and its development resulting from a great number of highly sensitive observations and the application of contemporary physical theories to the entire universe. The questions are assessed of mass density in the universe, the structure and origin of the universe, its baryon asymmetry and the quantum explanation of the origin of the universe. Physical problems are presented which should be resolved for the future development of cosmology. (Ha)
CERN. Geneva
2007-01-01
The understanding of the Universe at the largest and smallest scales traditionally has been the subject of cosmology and particle physics, respectively. Studying the evolution of the Universe connects today's large scales with the tiny scales in the very early Universe and provides the link between the physics of particles and of the cosmos. This series of five lectures aims at a modern and critical presentation of the basic ideas, methods, models and observations in today's particle cosmology.
Perturbations in loop quantum cosmology
International Nuclear Information System (INIS)
Nelson, W; Agullo, I; Ashtekar, A
2014-01-01
The era of precision cosmology has allowed us to accurately determine many important cosmological parameters, in particular via the CMB. Confronting Loop Quantum Cosmology with these observations provides us with a powerful test of the theory. For this to be possible, we need a detailed understanding of the generation and evolution of inhomogeneous perturbations during the early, quantum gravity phase of the universe. Here, we have described how Loop Quantum Cosmology provides a completion of the inflationary paradigm, that is consistent with the observed power spectra of the CMB
Voter Perceptions: Common Core State Standards & Tests
Achieve, Inc., 2014
2014-01-01
Since June 2010, 46 states and Washington DC have adopted the Common Core State Standards (CCSS)--K-12 standards in mathematics and English language arts/literacy developed through a multi-state initiative led by the National Governors Association and the Council of Chief State School Officers. Implementation of the standards is underway in all of…
Cosmological evolution of the Higgs boson's vacuum expectation value
Energy Technology Data Exchange (ETDEWEB)
Calmet, Xavier [University of Sussex, Department of Physics and Astronomy, Brighton (United Kingdom)
2017-11-15
We point out that the expansion of the universe leads to a cosmological time evolution of the vacuum expectation of the Higgs boson. Within the standard model of particle physics, the cosmological time evolution of the vacuum expectation of the Higgs leads to a cosmological time evolution of the masses of the fermions and of the electroweak gauge bosons, while the scale of Quantum Chromodynamics (QCD) remains constant. Precise measurements of the cosmological time evolution of μ = m{sub e}/m{sub p}, where m{sub e} and m{sub p} are, respectively, the electron and proton mass (which is essentially determined by the QCD scale), therefore provide a test of the standard models of particle physics and of cosmology. This ratio can be measured using modern atomic clocks. (orig.)
CERN. Geneva
2000-01-01
Most of the puzzles with standard big bang cosmology can be avoided if the big bang is NOT identified with the beginning of time. The short-distance cutoff and duality symmetries of superstring theory suggest a new (so-called pre-big bang) cosmology in which the birth of our Universe is the result of a long classical evolution characterized by a gravitational instability. I will motivate and describe this heretical scenario and compare its phenomenological implications with those of ortodox (post-big bang) inflation.
International Nuclear Information System (INIS)
Marrakchi, A.E.L.; Tapia, V.
1992-05-01
Some cosmological implications of the recently proposed fourth-rank theory of gravitation are studied. The model exhibits the possibility of being free from the horizon and flatness problems at the price of introducing a negative pressure. The field equations we obtain are compatible with k obs =0 and Ω obs t clas approx. 10 20 t Planck approx. 10 -23 s. When interpreted at the light of General Relativity the treatment is shown to be almost equivalent to that of the standard model of cosmology combined with the inflationary scenario. Hence, an interpretation of the negative pressure hypothesis is provided. (author). 8 refs
Standard Model theory calculations and experimental tests
International Nuclear Information System (INIS)
Cacciari, M.; Hamel de Monchenault, G.
2015-01-01
To present knowledge, all the physics at the Large Hadron Collider (LHC) can be described in the framework of the Standard Model (SM) of particle physics. Indeed the newly discovered Higgs boson with a mass close to 125 GeV seems to confirm the predictions of the SM. Thus, besides looking for direct manifestations of the physics beyond the SM, one of the primary missions of the LHC is to perform ever more stringent tests of the SM. This requires not only improved theoretical developments to produce testable predictions and provide experiments with reliable event generators, but also sophisticated analyses techniques to overcome the formidable experimental environment of the LHC and perform precision measurements. In the first section, we describe the state of the art of the theoretical tools and event generators that are used to provide predictions for the production cross sections of the processes of interest. In section 2, inclusive cross section measurements with jets, leptons and vector bosons are presented. Examples of differential cross sections, charge asymmetries and the study of lepton pairs are proposed in section 3. Finally, in section 4, we report studies on the multiple production of gauge bosons and constraints on anomalous gauge couplings
Common Core Standards and their Impact on Standardized Test Design
Polleck, J.N.; Jeffery, J.V.
2017-01-01
With adoption of the Common Core (CCSS) in a majority of U.S. states came developmentof new high-stakes exams. Though researchers have investigated CCSS andrelated policies, less attention has been directed toward understanding how standardsare translated into testing. Due to the influence that
Modified General Relativity and Cosmology
Abdel-Rahman, A.-M. M.
1997-10-01
Aspects of the modified general relativity theory of Rastall, Al-Rawaf and Taha are discussed in both the radiation- and matter-dominated flat cosmological models. A nucleosynthesis constraint on the theory's free parameter is obtained and the implication for the age of the Universe is discussed. The consistency of the modified matter- dominated model with the neoclassical cosmological tests is demonstrated.
Sinha, Manodeep; Berlind, Andreas A.; McBride, Cameron K.; Scoccimarro, Roman; Piscionere, Jennifer A.; Wibking, Benjamin D.
2018-04-01
Interpreting the small-scale clustering of galaxies with halo models can elucidate the connection between galaxies and dark matter halos. Unfortunately, the modelling is typically not sufficiently accurate for ruling out models statistically. It is thus difficult to use the information encoded in small scales to test cosmological models or probe subtle features of the galaxy-halo connection. In this paper, we attempt to push halo modelling into the "accurate" regime with a fully numerical mock-based methodology and careful treatment of statistical and systematic errors. With our forward-modelling approach, we can incorporate clustering statistics beyond the traditional two-point statistics. We use this modelling methodology to test the standard ΛCDM + halo model against the clustering of SDSS DR7 galaxies. Specifically, we use the projected correlation function, group multiplicity function and galaxy number density as constraints. We find that while the model fits each statistic separately, it struggles to fit them simultaneously. Adding group statistics leads to a more stringent test of the model and significantly tighter constraints on model parameters. We explore the impact of varying the adopted halo definition and cosmological model and find that changing the cosmology makes a significant difference. The most successful model we tried (Planck cosmology with Mvir halos) matches the clustering of low luminosity galaxies, but exhibits a 2.3σ tension with the clustering of luminous galaxies, thus providing evidence that the "standard" halo model needs to be extended. This work opens the door to adding interesting freedom to the halo model and including additional clustering statistics as constraints.
International Nuclear Information System (INIS)
Wesson, P.S.
1979-01-01
The Cosmological Principle states: the universe looks the same to all observers regardless of where they are located. To most astronomers today the Cosmological Principle means the universe looks the same to all observers because density of the galaxies is the same in all places. A new Cosmological Principle is proposed. It is called the Dimensional Cosmological Principle. It uses the properties of matter in the universe: density (rho), pressure (p), and mass (m) within some region of space of length (l). The laws of physics require incorporation of constants for gravity (G) and the speed of light (C). After combining the six parameters into dimensionless numbers, the best choices are: 8πGl 2 rho/c 2 , 8πGl 2 rho/c 4 , and 2 Gm/c 2 l (the Schwarzchild factor). The Dimensional Cosmological Principal came about because old ideas conflicted with the rapidly-growing body of observational evidence indicating that galaxies in the universe have a clumpy rather than uniform distribution
Interpreting Results from the Standardized UXO Test Sites
National Research Council Canada - National Science Library
May, Michael; Tuley, Michael
2007-01-01
...) and the Environmental Security Technology Certification Program (ESCTP) to complete a detailed analysis of the results of testing carried out at the Standardized Unexploded Ordnance (UXO) Test Sites...
Standard Ship Test and Inspection Plan, Procedures and Database
National Research Council Canada - National Science Library
1999-01-01
... construction schedules and increased cost is the area of test and inspection. This project investigates existing rules and regulations for testing and inspection of commercial ships and identifies differences and similarities within the requirements. The results include comparison matrices, a standard test plan, a set of standard test procedures, and a sample test database developed for a typical commercial ship.
Standardized Testing and the Construction of Governable Persons
Graham, Cameron; Neu, Dean
2004-01-01
While debates over standardized testing are ubiquitous, there has been relatively little consideration of how today's standardized testing practices have arisen. The current study provides a chronology of standardized testing within Alberta, Canada. Starting from prior work by Foucault and others on "governmentality", we propose that the…
Standard Guide for Testing Polymer Matrix Composite Materials
American Society for Testing and Materials. Philadelphia
2011-01-01
1.1 This guide summarizes the application of ASTM standard test methods (and other supporting standards) to continuous-fiber reinforced polymer matrix composite materials. The most commonly used or most applicable ASTM standards are included, emphasizing use of standards of Committee D30 on Composite Materials. 1.2 This guide does not cover all possible standards that could apply to polymer matrix composites and restricts discussion to the documented scope. Commonly used but non-standard industry extensions of test method scopes, such as application of static test methods to fatigue testing, are not discussed. A more complete summary of general composite testing standards, including non-ASTM test methods, is included in the Composite Materials Handbook (MIL-HDBK-17). Additional specific recommendations for testing textile (fabric, braided) composites are contained in Guide D6856. 1.3 This guide does not specify a system of measurement; the systems specified within each of the referenced standards shall appl...
Big-bang nucleosynthesis in the new cosmology
International Nuclear Information System (INIS)
Fields, B.D.
2005-01-01
Big bang nucleosynthesis (BBN) describes the production of the lightest elements in the first minutes of cosmic time. I will review the physics of cosmological element production, and the observations of the primordial element abundances. The comparison between theory and observation has heretofore provided our earliest probe of the universe, and given the best measure of the cosmic baryon content. However, BBN has now taken a new role in cosmology, in light of new precision measurements of the cosmic microwave background (CMB). Recent CMB anisotropy data yield a wealth of cosmological parameters; in particular, the baryon-to-photon ratio η = n B /n γ is measured to high precision. The confrontation between the BBN and CMB 'baryometers' poses a new and stringent test of the standard cosmology; the status of this test will be discussed. Moreover, it is now possible to recast the role of BBN by using the CMB to fix the baryon density and even some light element abundances. This strategy sharpens BBN into a more powerful probe of early universe physics, and of galactic nucleosynthesis processes. The impact of the CMB results on particle physics beyond the Standard Model, and on non-standard cosmology, will be illustrated. Prospects for improvement of these bounds via additional astronomical observations and nuclear experiments will be discussed, as will the lingering 'lithium problem.' (author)
International Nuclear Information System (INIS)
Dickau, Jonathan J.
2009-01-01
The use of fractals and fractal-like forms to describe or model the universe has had a long and varied history, which begins long before the word fractal was actually coined. Since the introduction of mathematical rigor to the subject of fractals, by Mandelbrot and others, there have been numerous cosmological theories and analyses of astronomical observations which suggest that the universe exhibits fractality or is by nature fractal. In recent years, the term fractal cosmology has come into usage, as a description for those theories and methods of analysis whereby a fractal nature of the cosmos is shown.
Testing the Standard Model with the Primordial Inflation Explorer
Kogut, Alan J.
2011-01-01
The Primordial Inflation Explorer is an Explorer-class mission to measure the gravity-wave signature of primordial inflation through its distinctive imprint on the linear polarization of the cosmic microwave background. PIXIE uses an innovative optical design to achieve background-limited sensitivity in 400 spectral channels spanning 2.5 decades in frequency from 30 GHz to 6 THz (1 cm to 50 micron wavelength). The principal science goal is the detection and characterization of linear polarization from an inflationary epoch in the early universe, with tensor-to-scalar ratio r < 10A{-3) at 5 standard deviations. The rich PIXIE data set will also constrain physical processes ranging from Big Bang cosmology to the nature of the first stars to physical conditions within the interstellar medium of the Galaxy. I describe the PIXIE instrument and mission architecture needed to detect the inflationary signature using only 4 semiconductor bolometers.
Energy Technology Data Exchange (ETDEWEB)
Turner, Michael S
1999-03-01
For two decades the hot big-bang model as been referred to as the standard cosmology - and for good reason. For just as long cosmologists have known that there are fundamental questions that are not answered by the standard cosmology and point to a grander theory. The best candidate for that grander theory is inflation + cold dark matter. It holds that the Universe is flat, that slowly moving elementary particles left over from the earliest moments provide the cosmic infrastructure, and that the primeval density inhomogeneities that seed all the structure arose from quantum fluctuations. There is now prima facie evidence that supports two basic tenets of this paradigm. An avalanche of high-quality cosmological observations will soon make this case stronger or will break it. Key questions remain to be answered; foremost among them are: identification and detection of the cold dark matter particles and elucidation of the dark-energy component. These are exciting times in cosmology{exclamation_point}.
Standard test methods for rockwell hardness of metallic materials
American Society for Testing and Materials. Philadelphia
2011-01-01
1.1 These test methods cover the determination of the Rockwell hardness and the Rockwell superficial hardness of metallic materials by the Rockwell indentation hardness principle. This standard provides the requirements for Rockwell hardness machines and the procedures for performing Rockwell hardness tests. 1.2 This standard includes additional requirements in annexes: Verification of Rockwell Hardness Testing Machines Annex A1 Rockwell Hardness Standardizing Machines Annex A2 Standardization of Rockwell Indenters Annex A3 Standardization of Rockwell Hardness Test Blocks Annex A4 Guidelines for Determining the Minimum Thickness of a Test Piece Annex A5 Hardness Value Corrections When Testing on Convex Cylindrical Surfaces Annex A6 1.3 This standard includes nonmandatory information in appendixes which relates to the Rockwell hardness test. List of ASTM Standards Giving Hardness Values Corresponding to Tensile Strength Appendix X1 Examples of Procedures for Determining Rockwell Hardness Uncertainty Appendix X...
Standard test methods for rockwell hardness of metallic materials
American Society for Testing and Materials. Philadelphia
2008-01-01
1.1 These test methods cover the determination of the Rockwell hardness and the Rockwell superficial hardness of metallic materials by the Rockwell indentation hardness principle. This standard provides the requirements for Rockwell hardness machines and the procedures for performing Rockwell hardness tests. 1.2 This standard includes additional requirements in annexes: Verification of Rockwell Hardness Testing Machines Annex A1 Rockwell Hardness Standardizing Machines Annex A2 Standardization of Rockwell Indenters Annex A3 Standardization of Rockwell Hardness Test Blocks Annex A4 Guidelines for Determining the Minimum Thickness of a Test Piece Annex A5 Hardness Value Corrections When Testing on Convex Cylindrical Surfaces Annex A6 1.3 This standard includes nonmandatory information in appendixes which relates to the Rockwell hardness test. List of ASTM Standards Giving Hardness Values Corresponding to Tensile Strength Appendix X1 Examples of Procedures for Determining Rockwell Hardness Uncertainty Appendix X...
Enqvist, K
2012-01-01
The very basics of cosmological inflation are discussed. We derive the equations of motion for the inflaton field, introduce the slow-roll parameters, and present the computation of the inflationary perturbations and their connection to the temperature fluctuations of the cosmic microwave background.
Ellis, G F R
1993-01-01
Many topics were covered in the submitted papers, showing much life in this subject at present. They ranged from conventional calculations in specific cosmological models to provocatively speculative work. Space and time restrictions required selecting from them, for summarisation here; the book of Abstracts should be consulted for a full overview.
International Nuclear Information System (INIS)
Chow, Nathan; Khoury, Justin
2009-01-01
We study the cosmology of a galileon scalar-tensor theory, obtained by covariantizing the decoupling Lagrangian of the Dvali-Gabadadze-Poratti (DGP) model. Despite being local in 3+1 dimensions, the resulting cosmological evolution is remarkably similar to that of the full 4+1-dimensional DGP framework, both for the expansion history and the evolution of density perturbations. As in the DGP model, the covariant galileon theory yields two branches of solutions, depending on the sign of the galileon velocity. Perturbations are stable on one branch and ghostlike on the other. An interesting effect uncovered in our analysis is a cosmological version of the Vainshtein screening mechanism: at early times, the galileon dynamics are dominated by self-interaction terms, resulting in its energy density being suppressed compared to matter or radiation; once the matter density has redshifted sufficiently, the galileon becomes an important component of the energy density and contributes to dark energy. We estimate conservatively that the resulting expansion history is consistent with the observed late-time cosmology, provided that the scale of modification satisfies r c > or approx. 15 Gpc.
A new cosmological paradigm: the cosmological constant and dark matter
International Nuclear Information System (INIS)
Krauss, L.M.
1998-01-01
The Standard Cosmological Model of the 1980 close-quote s is no more. I describe the definitive evidence that the density of matter is insufficient to result in a flat universe, as well as the mounting evidence that the cosmological constant is not zero. I finally discuss the implications of these results for particle physics and direct searches for non-baryonic dark matter. copyright 1998 American Institute of Physics
Bioassessment of the Standard Elutriate Test
1976-09-01
that the growth of the green algal, Chlorella vulgaris , was reduced approximately 50 percent in the presence of 2.0 ppm zinc. Payne (12) reported that...Environmental Protection Agency, Washington, DC, Oct., 1973. 14. Rachlin, Y. W., and Farran, M., "Growth Response of the Green Algae Chlorella ... vulgaris to Selective Concentrations of Zinc," Water Research, Vol. 8, 1974, pp. 575-577. 1:). Standard Methods for the Examination of Water and Wastewater
Towards a standardization of biomethane potential tests.
Holliger, Christof; Alves, Madalena; Andrade, Diana; Angelidaki, Irini; Astals, Sergi; Baier, Urs; Bougrier, Claire; Buffière, Pierre; Carballa, Marta; de Wilde, Vinnie; Ebertseder, Florian; Fernández, Belén; Ficara, Elena; Fotidis, Ioannis; Frigon, Jean-Claude; de Laclos, Hélène Fruteau; Ghasimi, Dara S M; Hack, Gabrielle; Hartel, Mathias; Heerenklage, Joern; Horvath, Ilona Sarvari; Jenicek, Pavel; Koch, Konrad; Krautwald, Judith; Lizasoain, Javier; Liu, Jing; Mosberger, Lona; Nistor, Mihaela; Oechsner, Hans; Oliveira, João Vítor; Paterson, Mark; Pauss, André; Pommier, Sébastien; Porqueddu, Isabella; Raposo, Francisco; Ribeiro, Thierry; Rüsch Pfund, Florian; Strömberg, Sten; Torrijos, Michel; van Eekert, Miriam; van Lier, Jules; Wedwitschka, Harald; Wierinck, Isabella
2016-12-01
Production of biogas from different organic materials is a most interesting source of renewable energy. The biomethane potential (BMP) of these materials has to be determined to get insight in design parameters for anaerobic digesters. Although several norms and guidelines for BMP tests exist, inter-laboratory tests regularly show high variability of BMPs for the same substrate. A workshop was held in June 2015, in Leysin, Switzerland, with over 40 attendees from 30 laboratories around the world, to agree on common solutions to the conundrum of inconsistent BMP test results. This paper presents the consensus of the intense roundtable discussions and cross-comparison of methodologies used in respective laboratories. Compulsory elements for the validation of BMP results were defined. They include the minimal number of replicates, the request to carry out blank and positive control assays, a criterion for the test duration, details on BMP calculation, and last but not least criteria for rejection of the BMP tests. Finally, recommendations on items that strongly influence the outcome of BMP tests such as inoculum characteristics, substrate preparation, test setup, and data analysis are presented to increase the probability of obtaining validated and reproducible results.
International Nuclear Information System (INIS)
Schramm, D.N.
1995-01-01
Primordial nucleosynthesis has established itself as one of the three pillars of Big Bang cosmology. Many of the Big Bang Nucleosynthesis reactions involve unstable nuclei. Hence there is a tight relationship hetween the subject of this conference and cosmology. The prime role of unstable nuclei in cosmology is related to lithium synthesis and the lack of cosmological synthesis of Be and B. These nuclei will thus be focused upon. Nucleosynthesis involves comparing calculated abundances with observed abundances. In general, abundance determinations are dominated by systematic rather than statistical errors, and work on bounding systematics is crucial. The quark-hadron inspired inhomogeneous calculations now unanimously agree that only relatively small variations in Ω b are possible vis-a-vis the homogeneous model; hence the robustness of Ω b ∼0.05 is now apparent. (These calculations depend critically on unstable nuclei.) The above argues that the bulk of the baryons in the universe are not producing visible light. A comparison with the ROSAT cluster data is also shown to be consistent with the standard BBN model. Ω b ∼1 seems to be definitely excluded, so if Ω TOTAL =1, as some recent observations may hint, then non-baryonic dark matter is required. The implications of the recently reported halo microlensing events are discussed. In summary, it is argued that the physics of unstable nuclei affects the fundamental dark matter argument. ((orig.))
Ekpyrotic and cyclic cosmology
International Nuclear Information System (INIS)
Lehners, Jean-Luc
2008-01-01
Ekpyrotic and cyclic cosmologies provide theories of the very early and of the very late universe. In these models, the big bang is described as a collision of branes - and thus the big bang is not the beginning of time. Before the big bang, there is an ekpyrotic phase with equation of state w=P/(ρ) >>1 (where P is the average pressure and ρ the average energy density) during which the universe slowly contracts. This phase resolves the standard cosmological puzzles and generates a nearly scale-invariant spectrum of cosmological perturbations containing a significant non-Gaussian component. At the same time it produces small-amplitude gravitational waves with a blue spectrum. The dark energy dominating the present-day cosmological evolution is reinterpreted as a small attractive force between our brane and a parallel one. This force eventually induces a new ekpyrotic phase and a new brane collision, leading to the idea of a cyclic universe. This review discusses the detailed properties of these models, their embedding in M-theory and their viability, with an emphasis on open issues and observational signatures
On the behaviour of test matter in the neighbourhood of caustics of homogeneous cosmological models
International Nuclear Information System (INIS)
Paul, H.G.
1983-01-01
Using power asymptotes for the metric of the BIANCHI types I, V, VII 0 , VIII and IX the intensity of geodesic focused scalar test matter is calculated in the neighbourhood of the caustic singularity of these space-time models. In all considered BIANCHI types there is a caustic diffraction with a diffraction field bounded by regions of extinction depending on the structure of the gravitational lense. (author)
42 CFR 493.1281 - Standard: Comparison of test results.
2010-10-01
... 42 Public Health 5 2010-10-01 2010-10-01 false Standard: Comparison of test results. 493.1281 Section 493.1281 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN... Testing Analytic Systems § 493.1281 Standard: Comparison of test results. (a) If a laboratory performs the...
Towards a standardization of biomethane potential tests
DEFF Research Database (Denmark)
Holliger, C.; Alves, M.; Andrade, D.
2016-01-01
Production of biogas fromdifferent organic materials is a most interesting source of renewable energy. The biomethane potential (BMP) of these materials has to be determined to get insight in design parameters for anaerobic digesters. Although several norms and guidelines for BMP tests exist, int...
Standard guide for fretting fatigue testing
American Society for Testing and Materials. Philadelphia
2010-01-01
1.1 This guide defines terminology and covers general requirements for conducting fretting fatigue tests and reporting the results. It describes the general types of fretting fatigue tests and provides some suggestions on developing and conducting fretting fatigue test programs. 1.2 Fretting fatigue tests are designed to determine the effects of mechanical and environmental parameters on the fretting fatigue behavior of metallic materials. This guide is not intended to establish preference of one apparatus or specimen design over others, but will establish guidelines for adherence in the design, calibration, and use of fretting fatigue apparatus and recommend the means to collect, record, and reporting of the data. 1.3 The number of cycles to form a fretting fatigue crack is dependent on both the material of the fatigue specimen and fretting pad, the geometry of contact between the two, and the method by which the loading and displacement are imposed. Similar to wear behavior of materials, it is important t...
Cosmological Non-Gaussian Signature Detection: Comparing Performance of Different Statistical Tests
Directory of Open Access Journals (Sweden)
O. Forni
2005-09-01
Full Text Available Currently, it appears that the best method for non-Gaussianity detection in the cosmic microwave background (CMB consists in calculating the kurtosis of the wavelet coefficients. We know that wavelet-kurtosis outperforms other methods such as the bispectrum, the genus, ridgelet-kurtosis, and curvelet-kurtosis on an empirical basis, but relatively few studies have compared other transform-based statistics, such as extreme values, or more recent tools such as higher criticism (HC, or proposed Ã¢Â€Âœbest possibleÃ¢Â€Â choices for such statistics. In this paper, we consider two models for transform-domain coefficients: (a a power-law model, which seems suited to the wavelet coefficients of simulated cosmic strings, and (b a sparse mixture model, which seems suitable for the curvelet coefficients of filamentary structure. For model (a, if power-law behavior holds with finite 8th moment, excess kurtosis is an asymptotically optimal detector, but if the 8th moment is not finite, a test based on extreme values is asymptotically optimal. For model (b, if the transform coefficients are very sparse, a recent test, higher criticism, is an optimal detector, but if they are dense, kurtosis is an optimal detector. Empirical wavelet coefficients of simulated cosmic strings have power-law character, infinite 8th moment, while curvelet coefficients of the simulated cosmic strings are not very sparse. In all cases, excess kurtosis seems to be an effective test in moderate-resolution imagery.
Use of supernovae light curves for testing the expansion hypothesis and other cosmological relations
International Nuclear Information System (INIS)
Rust, B.W.
1974-01-01
This thesis is primarily concerned with a test of the expansion hypothesis based on the relation Δt/sub obs/ = (1 + V/sub r//c)Δt/sub int/ where Δt/sub int/ is the time lapse characterizing some phenomenon in a distant galaxy, Δt/sub obs/ is the observed time lapse and V/sub r/ is the symbolic velocity of recession. If the red shift is a Doppler effect, the observed time lapse should be lengthened by the same factor as the wave length of the light. Many authors have suggested type I supernovae for such a test because of their great luminosity and the uniformity of their light curves, but apparently the test has heretofore never actually been performed. Thirty-six light curves were gathered from the literature and one (SN1971i) was measured. All of the light curves were reduced to a common (m/sub pg/) photometric system. The comparison time lapse, Δt/sub c/, was taken to be the time required for the brightness to fall from 0.5 m below peak to 2.5 m below peak. The straight line regression of Δt/sub c/ on V/sub r/ gives a correlation coefficient significant at the 93 percent level, and the simple static Euclidean hypothesis is rejected at that level. The regression line also deviates from the prediction of the classical expansion hypothesis. Better agreement was obtained using the chronogeometric theory of I. E. Segal ( []972 Astron. and Astrophys. 18, 143), but the scatter in the present data makes it impossible to distinguish between these alternate hypotheses at the 95 percent confidence level. The question of how many additional light curves would be needed to give definite tests is addressed. It is shown that at the present rate of supernova discoveries, only a few more years would be required to obtain the necessary data if light curves are systematically measured for the more distant supernovae. (Diss. Abstr. Int., B)
Grant, E.; Murdin, P.
2000-11-01
During the early Middle Ages (ca 500 to ca 1130) scholars with an interest in cosmology had little useful and dependable literature. They relied heavily on a partial Latin translation of PLATO's Timaeus by Chalcidius (4th century AD), and on a series of encyclopedic treatises associated with the names of Pliny the Elder (ca AD 23-79), Seneca (4 BC-AD 65), Macrobius (fl 5th century AD), Martianus ...
Greene, Benjamin; McClure, Mark B.
2012-01-01
The NASA Johnson Space Center White Sands Test Facility (WSTF) has performed testing of hazardous and reactive aerospace fluids, including hypergolic propellants, with materials since the 1960s with the Apollo program. Amongst other test activities, Test 15 is a NASA standard test for evaluating the reactivity of materials with selected aerospace fluids, in particular hydrazine, monomethylhydrazine, uns-dimethylhydrazine, Aerozine 50, dinitrogen tetroxide oxidizers, and ammonia. This manuscript provides an overview of the history of Test 15 over a timeline ranging from prior to its development and first implementation as a NASA standard test in 1974 to its current refinement. Precursor documents to NASA standard tests, as they are currently known, are reviewed. A related supplementary test, international standardization, and enhancements to Test 15 are also discussed. Because WSTF was instrumental in the development and implementation of Test 15, WSTF experience and practices are referred to in this manuscript.
Standard test method for creep-fatigue testing
American Society for Testing and Materials. Philadelphia
2009-01-01
1.1 This test method covers the determination of mechanical properties pertaining to creep-fatigue deformation or crack formation in nominally homogeneous materials, or both by the use of test specimens subjected to uniaxial forces under isothermal conditions. It concerns fatigue testing at strain rates or with cycles involving sufficiently long hold times to be responsible for the cyclic deformation response and cycles to crack formation to be affected by creep (and oxidation). It is intended as a test method for fatigue testing performed in support of such activities as materials research and development, mechanical design, process and quality control, product performance, and failure analysis. The cyclic conditions responsible for creep-fatigue deformation and cracking vary with material and with temperature for a given material. 1.2 The use of this test method is limited to specimens and does not cover testing of full-scale components, structures, or consumer products. 1.3 This test method is primarily ...
the Universe About Cosmology Planck Satellite Launched Cosmology Videos Professor George Smoot's group conducts research on the early universe (cosmology) using the Cosmic Microwave Background radiation (CMB science goals regarding cosmology. George Smoot named Director of Korean Cosmology Institute The GRB
American Society for Testing and Materials. Philadelphia
1985-01-01
1.1 This test method covers a procedure for a laboratory test for performing an initial evaluation (screening) of nonmetallic seal materials by immersion in a simulated geothermal test fluid. 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific precautionary statements, see Section 6 and 11.7.
International Nuclear Information System (INIS)
Schramm, D.N.
1989-12-01
Nuclear physics has provided one of the 2 critical observational tests of all Big Bang cosmology, namely Big Bang Nucleosynthesis. Furthermore, this same nuclear physics input enables a prediction to be made about one of the most fundamental physics questions of all, the number of elementary particle families. This paper reviews the standard Big Bang Nucleosynthesis arguments. The primordial He abundance is inferred from He--C and He--N and He--O correlations. The strengthened Li constraint as well as 2 D plus 3 He are used to limit the baryon density. This limit is the key argument behind the need for non-baryonic dark matter. The allowed number of neutrino families, N ν , is delineated using the new neutron lifetime value of τ n = 890 ± 4s (τ 1/2 = 10.3 min). The formal statistical result is N ν = 2.6 ± 0.3 (1σ) providing a reasonable fit (1.3σ) to 3 families but making a fourth light (m ν approx-lt 10 MeV) neutrino family exceedingly unlikely (approx-gt 4.7σ) (barring significant systematic errors either in D + 3 He, and Li and/or 4 He and/or τ n ). It is also shown that uncertainties induced by postulating a first-order quark-hadron phase transition do not seriously affect the conclusions. 21 refs., 3 figs
Schramm, David N.
1989-01-01
Nuclear physics has provided one of two critical observational tests of all Big Bang cosmology, namely Big Bang Nucleosynthesis. Furthermore, this same nuclear physics input enables a prediction to be made about one of the most fundamental physics questions of all, the number of elementary particle families. The standard Big Bang Nucleosynthesis arguments are reviewed. The primordial He abundance is inferred from He-C and He-N and He-O correlations. The strengthened Li constraint as well as D-2 plus He-3 are used to limit the baryon density. This limit is the key argument behind the need for non-baryonic dark matter. The allowed number of neutrino families, N(nu), is delineated using the new neutron lifetime value of tau(n) = 890 + or - 4s (tau(1/2) = 10.3 min). The formal statistical result is N(nu) = 2.6 + or - 0.3 (1 sigma), providing a reasonable fit (1.3 sigma) to three families but making a fourth light (m(nu) less than or equal to 10 MeV) neutrino family exceedly unlikely (approx. greater than 4.7 sigma). It is also shown that uncertainties induced by postulating a first-order quark-baryon phase transition do not seriously affect the conclusions.
Collett, Thomas E; Bacon, David
2017-03-03
Probing the relative speeds of gravitational waves and light acts as an important test of general relativity and alternative theories of gravity. Measuring the arrival time of gravitational waves (GWs) and electromagnetic (EM) counterparts can be used to measure the relative speeds, but only if the intrinsic time lag between emission of the photons and gravitational waves is well understood. Here we suggest a method that does not make such an assumption, using future strongly lensed GW events and EM counterparts; Biesiada et al. [J. Cosmol. Astropart. Phys.10 (2014) 080JCAPBP1475-751610.1088/1475-7516/2014/10/080] forecast that 50-100 strongly lensed GW events will be observed each year with the Einstein Telescope. A single strongly lensed GW event would produce robust constraints on c_{GW}/c_{γ} at the 10^{-7} level, if a high-energy EM counterpart is observed within the field of view of an observing γ-ray burst monitor.
International Nuclear Information System (INIS)
Tamura, Yoshikazu
2011-01-01
Domestic standards of the leak testing are enacted as one of Japan Industrial Standards. The conformity is advanced between these domestic standards and ISO (International Organization for Standardization) standard. ISO9712 (Non-destructive testing-Qualification and certification of personnel) was revised to include the leak testing of qualification and certification in 2005. The preparation working group of qualification and certification for leak testing is planning start aiming at the system in one and a half years. (author)
Cosmic numbers: A physical classification for cosmological models
International Nuclear Information System (INIS)
Avelino, P.P.; Martins, C.J.A.P.
2003-01-01
We introduce the notion of the cosmic numbers of a cosmological model, and discuss how they can be used to naturally classify models according to their ability to solve some of the problems of the standard cosmological model
Development of standard testing methods for nuclear-waste forms
International Nuclear Information System (INIS)
Mendel, J.E.; Nelson, R.D.
1981-11-01
Standard test methods for waste package component development and design, safety analyses, and licensing are being developed for the Nuclear Waste Materials Handbook. This paper describes mainly the testing methods for obtaining waste form materials data
Value of the Cosmological Constant in Emergent Quantum Gravity
Energy Technology Data Exchange (ETDEWEB)
Hogan, Craig [Fermilab
2018-03-30
It is suggested that the exact value of the cosmological constant could be derived from first principles, based on entanglement of the Standard Model field vacuum with emergent holographic quantum geometry. For the observed value of the cosmological constant, geometrical information is shown to agree closely with the spatial information density of the QCD vacuum, estimated in a free-field approximation. The comparison is motivated by a model of exotic rotational fluctuations in the inertial frame that can be precisely tested in laboratory experiments. Cosmic acceleration in this model is always positive, but fluctuates with characteristic coherence length $\\approx 100$km and bandwidth $\\approx 3000$ Hz.
DOE standard: Quality assurance inspection and testing of HEPA filters
International Nuclear Information System (INIS)
1999-02-01
This standard establishes essential elements for the quality assurance inspection and testing of HEPA filters by US Department of Energy (DOE)-accepted Filter Test Facilities (FTF). The standard specifies HEPA filter quality assurance inspection and testing practices established in DOE-STD-3022-98, DOE HEPA Filter Test Program, and provides a basis for the preparation of written operating procedures for primary FTF functions
Gravitational particle production in braneworld cosmology.
Bambi, C; Urban, F R
2007-11-09
Gravitational particle production in a time variable metric of an expanding universe is efficient only when the Hubble parameter H is not too small in comparison with the particle mass. In standard cosmology, the huge value of the Planck mass M{Pl} makes the mechanism phenomenologically irrelevant. On the other hand, in braneworld cosmology, the expansion rate of the early Universe can be much faster, and many weakly interacting particles can be abundantly created. Cosmological implications are discussed.
BOOK REVIEW: Observational Cosmology Observational Cosmology
Howell, Dale Andrew
2013-04-01
. However, these are usually pointed to in the 'further reading' section at the end of each chapter. I found this to be a welcome compromise: derivations are important but tedious; you should have access to them, but they would bog down a book such as this. Some of the experimental techniques of modern-day cosmology are of sufficient complexity that they require a thorough explanation of the particulars of an experiment intertwined with the fundamentals of cosmology. This is where the book both shines and stumbles. Learning spherical harmonics as an abstraction is a bore. But if you know it will help you to interpret the latest WMAP results, it seems like a vital tool. Pairing topics like these is great for motivation, but at times the execution is lacking. Spherical harmonics are dispensed with in a few paragraphs and a handful of equations. And there are no exercises provided to help students master the basics. This lack of outlets for students to test their knowledge is a serious issue. There are no problem sets at the end of each chapter. Occasionally an exercise is interspersed into the text, but these are relatively rare. The burden will be on the professor to come up with interesting problems to challenge students on most of the topics. A related problem is that the math in the book is too advanced for most undergraduates. After consultation with a British colleague, I don't think this is just a difference between expectations in the American and British systems. In addition to the aforementioned spherical harmonics, advanced Fourier techniques and complicated matrices are presented, with too little background provided. Even tensors are brushed on. Observational Cosmology also tries to serve as a kind of primer on the terminology used by cosmologists. Perhaps this is to help students understand talks, where knowledge of such esoterica as BzK galaxies, Schmidt laws, and Shapiro delays is assumed. This is admirable, and often succeeds, but the result is a book that is
Stress Optical Coefficient, Test Methodology, and Glass Standard Evaluation
2016-05-01
ARL-TN-0756 ● MAY 2016 US Army Research Laboratory Stress Optical Coefficient, Test Methodology , and Glass Standard Evaluation...Stress Optical Coefficient, Test Methodology , and Glass Standard Evaluation by Clayton M Weiss Oak Ridge Institute for Science and Education...ORISE), Belcamp, MD Parimal J Patel Weapons and Materials Research Directorate, ARL Approved for public release; distribution is
Standard Operating Procedure for Accelerated Corrosion Testing at ARL
2017-11-01
ARL-TN-0855 ● NOV 2017 US Army Research Laboratory Standard Operating Procedure for Accelerated Corrosion Testing at ARL by... Corrosion Testing at ARL by Thomas A Considine Weapons and Materials Research Directorate, ARL Approved for public...November 2017 2. REPORT TYPE Technical Note 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE Standard Operating Procedure for Accelerated
Standard test methods for bend testing of material for ductility
American Society for Testing and Materials. Philadelphia
2009-01-01
1.1 These test methods cover bend testing for ductility of materials. Included in the procedures are four conditions of constraint on the bent portion of the specimen; a guided-bend test using a mandrel or plunger of defined dimensions to force the mid-length of the specimen between two supports separated by a defined space; a semi-guided bend test in which the specimen is bent, while in contact with a mandrel, through a specified angle or to a specified inside radius (r) of curvature, measured while under the bending force; a free-bend test in which the ends of the specimen are brought toward each other, but in which no transverse force is applied to the bend itself and there is no contact of the concave inside surface of the bend with other material; a bend and flatten test, in which a transverse force is applied to the bend such that the legs make contact with each other over the length of the specimen. 1.2 After bending, the convex surface of the bend is examined for evidence of a crack or surface irregu...
International Nuclear Information System (INIS)
Desert, F.-Xavier
2004-01-01
After an introduction comprising some definitions, an historical overview, and a discussion of the paradoxical Universe, this course proposes a presentation of fundamental notions and theories, i.e. the restrained relativity and the universal gravitation. The next part addresses the general relativity with the following notions: space-time metrics and principle of generalised covariance, basics of tensor analysis, geodesics, energy-pulse tensor, curvature, Einstein equations, Newtonian limit, Schwarzschild metrics, gravitational waves, gravitational redshift. The next part addresses the standard cosmology with the Friedmann-Robertson-Walker metrics and the Friedmann-Lemaitre equations of the evolution of the Universe. The Universe expansion is then addressed: distances and horizons, Hubble law, determination of the Hubble constant. The next chapter deals with the constituents of the Universe: light matter, baryonic dark matter, black matter, supernovae, Universe acceleration and black energy. Then comes the nuclear evolution of the Universe: thermodynamics of the primordial Universe, the matter-antimatter asymmetry, from quarks to atoms, cosmic abundance, neutron cosmological background, matter-radiation equality, cosmo-chronology or the age of the Universe. The next chapter addresses the cosmological background at 3 K: sky electromagnetic spectrum, measurement of CMB anisotropies, interpretation of anisotropies, growth of perturbations. The last chapter addresses the quantum field theory and inflation: paradoxes of the standard Big Bang, the simple inflation, noticeable consequences
Bojowald, Martin
2015-02-01
In quantum cosmology, one applies quantum physics to the whole universe. While no unique version and no completely well-defined theory is available yet, the framework gives rise to interesting conceptual, mathematical and physical questions. This review presents quantum cosmology in a new picture that tries to incorporate the importance of inhomogeneity. De-emphasizing the traditional minisuperspace view, the dynamics is rather formulated in terms of the interplay of many interacting 'microscopic' degrees of freedom that describe the space-time geometry. There is thus a close relationship with more-established systems in condensed-matter and particle physics even while the large set of space-time symmetries (general covariance) requires some adaptations and new developments. These extensions of standard methods are needed both at the fundamental level and at the stage of evaluating the theory by effective descriptions.
Merritt, David
2017-02-01
I argue that some important elements of the current cosmological model are 'conventionalist' in the sense defined by Karl Popper. These elements include dark matter and dark energy; both are auxiliary hypotheses that were invoked in response to observations that falsified the standard model as it existed at the time. The use of conventionalist stratagems in response to unexpected observations implies that the field of cosmology is in a state of 'degenerating problemshift' in the language of Imre Lakatos. I show that the 'concordance' argument, often put forward by cosmologists in support of the current paradigm, is weaker than the convergence arguments that were made in the past in support of the atomic theory of matter or the quantization of energy.
Cosmology, inflation, and supersymmetry
International Nuclear Information System (INIS)
Albrecht, A.; Dimopoulos, S.; Fischler, W.; Kolb, E.W.; Raby, S.; Steinhardt, P.J.
1982-01-01
Cosmological consequences of supersymmetric grand unified models based on the Witten-O'Raifeartaigh potential are discussed. In particular we study the development of the phase transition in the spontaneous breaking of supersymmetry. We find that in realistic models where light fields feel supersymmetry breaking only through coupling to massive fields, e.g., the Geometric Hierarchy model, the universe does not inflate or reheat. Thus, the standard cosmological flatness, monopole, and horizon problems remain. In addition, we find that the transition is never completed, in the sense that the universe remains dominated by coherent Higgs field energy, resulting in an apparent matter dominated universe with Ω greater than or equal to 10 30
Magnetohydrodynamic cosmologies
International Nuclear Information System (INIS)
Portugal, R.; Soares, I.D.
1991-01-01
We analyse a class of cosmological models in magnetohydrodynamic regime extending and completing the results of a previous paper. The material content of the models is a perfect fluid plus electromagnetic fields. The fluid is neutral in average but admits an electrical current which satisfies Ohm's law. All models fulfil the physical requirements of near equilibrium thermodynamics and can be favourably used as a more realistic description of the interior of a collapsing star in a magnetohydrodynamic regime with or without a magnetic field. (author)
Bardeen, J. M.
The last several years have seen a tremendous ferment of activity in astrophysical cosmology. Much of the theoretical impetus has come from particle physics theories of the early universe and candidates for dark matter, but what promise to be even more significant are improved direct observations of high z galaxies and intergalactic matter, deeper and more comprehensive redshift surveys, and the increasing power of computer simulations of the dynamical evolution of large scale structure. Upper limits on the anisotropy of the microwave background radiation are gradually getting tighter and constraining more severely theoretical scenarios for the evolution of the universe.
International Nuclear Information System (INIS)
Bardeen, J.M.
1986-01-01
The last several years have seen a tremendous ferment of activity in astrophysical cosmology. Much of the theoretical impetus has come from particle physics theories of the early universe and candidates for dark matter, but what promise to be even more significant are improved direct observations of high z galaxies and intergalactic matter, deeper and more comprehensive redshift surveys, and the increasing power of computer simulations of the dynamical evolution of large scale structure. Upper limits on the anisotropy of the microwave background radiation are gradually getting tighter and constraining more severely theoretical scenarios for the evolution of the universe. 47 refs
Page, Don N.
2006-01-01
A complete model of the universe needs at least three parts: (1) a complete set of physical variables and dynamical laws for them, (2) the correct solution of the dynamical laws, and (3) the connection with conscious experience. In quantum cosmology, item (2) is the quantum state of the cosmos. Hartle and Hawking have made the `no-boundary' proposal, that the wavefunction of the universe is given by a path integral over all compact Euclidean 4-dimensional geometries and matter fields that hav...
Religion, theology and cosmology
Directory of Open Access Journals (Sweden)
John T. Fitzgerald
2013-10-01
Full Text Available Cosmology is one of the predominant research areas of the contemporary world. Advances in modern cosmology have prompted renewed interest in the intersections between religion, theology and cosmology. This article, which is intended as a brief introduction to the series of studies on theological cosmology in this journal, identifies three general areas of theological interest stemming from the modern scientific study of cosmology: contemporary theology and ethics; cosmology and world religions; and ancient cosmologies. These intersections raise important questions about the relationship of religion and cosmology, which has recently been addressed by William Scott Green and is the focus of the final portion of the article.
Standard test method for creep-fatigue crack growth testing
American Society for Testing and Materials. Philadelphia
2010-01-01
1.1 This test method covers the determination of creep-fatigue crack growth properties of nominally homogeneous materials by use of pre-cracked compact type, C(T), test specimens subjected to uniaxial cyclic forces. It concerns fatigue cycling with sufficiently long loading/unloading rates or hold-times, or both, to cause creep deformation at the crack tip and the creep deformation be responsible for enhanced crack growth per loading cycle. It is intended as a guide for creep-fatigue testing performed in support of such activities as materials research and development, mechanical design, process and quality control, product performance, and failure analysis. Therefore, this method requires testing of at least two specimens that yield overlapping crack growth rate data. The cyclic conditions responsible for creep-fatigue deformation and enhanced crack growth vary with material and with temperature for a given material. The effects of environment such as time-dependent oxidation in enhancing the crack growth ra...
Standard test method for liquid impingement erosion using rotating apparatus
American Society for Testing and Materials. Philadelphia
2010-01-01
1.1 This test method covers tests in which solid specimens are eroded or otherwise damaged by repeated discrete impacts of liquid drops or jets. Among the collateral forms of damage considered are degradation of optical properties of window materials, and penetration, separation, or destruction of coatings. The objective of the tests may be to determine the resistance to erosion or other damage of the materials or coatings under test, or to investigate the damage mechanisms and the effect of test variables. Because of the specialized nature of these tests and the desire in many cases to simulate to some degree the expected service environment, the specification of a standard apparatus is not deemed practicable. This test method gives guidance in setting up a test, and specifies test and analysis procedures and reporting requirements that can be followed even with quite widely differing materials, test facilities, and test conditions. It also provides a standardized scale of erosion resistance numbers applicab...
Radioactive material package test standards and performance requirements - public perception
International Nuclear Information System (INIS)
Pope, R.B.; Shappert, L.B.; Rawl, R.R.
1992-01-01
This paper addresses issues related to the public perception of the regulatory test standards and performance requirements for packaging and transporting radioactive material. Specifically, it addresses the adequacy of the package performance standards and testing for Type B packages, which are those packages designed for transporting the most hazardous quantities and forms of radioactive material. Type B packages are designed to withstand accident conditions in transport. To improve public perception, the public needs to better understand: (a) the regulatory standards and requirements themselves, (b) the extensive history underlying their development, and (c) the soundness of the technical foundation. The public needs to be fully informed on studies, tests, and analyses that have been carried out worldwide and form the basis of the regulatory standards and requirements. This paper provides specific information aimed at improving the public perception of packages test standards
Standard guide for conducting exfoliation corrosion tests in aluminum alloys
American Society for Testing and Materials. Philadelphia
1992-01-01
1.1 This guide differs from the usual ASTM standard in that it does not address a specific test. Rather, it is an introductory guide for new users of other standard exfoliation test methods, (see Terminology G 15 for definition of exfoliation). 1.2 This guide covers aspects of specimen preparation, exposure, inspection, and evaluation for conducting exfoliation tests on aluminum alloys in both laboratory accelerated environments and in natural, outdoor atmospheres. The intent is to clarify any gaps in existent test methods. 1.3 The values stated in SI units are to be regarded as the standard. The inch-pound units given in parentheses are for information only. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
International Nuclear Information System (INIS)
Chimento, L P; Forte, M; Devecchi, F P; Kremer, G M; Ribas, M O; Samojeden, L L
2011-01-01
In this work we review if fermionic sources could be responsible for accelerated periods during the evolution of a FRW universe. In a first attempt, besides the fermionic source, a matter constituent would answer for the decelerated periods. The coupled differential equations that emerge from the field equations are integrated numerically. The self-interaction potential of the fermionic field is considered as a function of the scalar and pseudo-scalar invariants. It is shown that the fermionic field could behave like an inflaton field in the early universe, giving place to a transition to a matter dominated (decelerated) period. In a second formulation we turn our attention to analytical results, specifically using the idea of form-invariance transformations. These transformations can be used for obtaining accelerated cosmologies starting with conventional cosmological models. Here we reconsider the scalar field case and extend the discussion to fermionic fields. Finally we investigate the role of a Dirac field in a Brans-Dicke (BD) context. The results show that this source, in combination with the BD scalar, promote a final eternal accelerated era, after a matter dominated period.
Combining experimental and cosmological constraints on heavy neutrinos
Directory of Open Access Journals (Sweden)
Marco Drewes
2017-08-01
Full Text Available We study experimental and cosmological constraints on the extension of the Standard Model by three right handed neutrinos with masses between those of the pion and W boson. We combine for the first time direct, indirect and cosmological constraints in this mass range. This includes experimental constraints from neutrino oscillation data, neutrinoless double β decay, electroweak precision data, lepton universality, searches for rare lepton decays, tests of CKM unitarity and past direct searches at colliders or fixed target experiments. On the cosmological side, big bang nucleosynthesis has the most pronounced impact. Our results can be used to evaluate the discovery potential of searches for heavy neutrinos at LHCb, BELLE II, SHiP, ATLAS, CMS or a future lepton collider.
Dark matter and dark energy a challenge for modern cosmology
Gorini, Vittorio; Moschella, Ugo; Matarrese, Sabino
2011-01-01
This book brings together reviews from leading international authorities on the developments in the study of dark matter and dark energy, as seen from both their cosmological and particle physics side. Studying the physical and astrophysical properties of the dark components of our Universe is a crucial step towards the ultimate goal of unveiling their nature. The work developed from a doctoral school sponsored by the Italian Society of General Relativity and Gravitation. The book starts with a concise introduction to the standard cosmological model, as well as with a presentation of the theory of linear perturbations around a homogeneous and isotropic background. It covers the particle physics and cosmological aspects of dark matter and (dynamical) dark energy, including a discussion of how modified theories of gravity could provide a possible candidate for dark energy. A detailed presentation is also given of the possible ways of testing the theory in terms of cosmic microwave background, galaxy redshift su...
Quantum Gravity and Cosmology: an intimate interplay
Sakellariadou, Mairi
2017-08-01
I will briefly discuss three cosmological models built upon three distinct quantum gravity proposals. I will first highlight the cosmological rôle of a vector field in the framework of a string/brane cosmological model. I will then present the resolution of the big bang singularity and the occurrence of an early era of accelerated expansion of a geometric origin, in the framework of group field theory condensate cosmology. I will then summarise results from an extended gravitational model based on non-commutative spectral geometry, a model that offers a purely geometric explanation for the standard model of particle physics.
International Nuclear Information System (INIS)
Fliche, H.-H.; Souriau, J.-M.
1978-03-01
On the basis of colorimetric data a composite spectrum of quasars is established from the visible to the Lyman's limit. Its agreement with the spectrum of the quasar 3C273, obtained directly, confirms the homogeneity of these objects. The compatibility of the following hypotheses: negligible evolution of quasars, Friedmann type model of the universe with cosmological constant, is studied by means of two tests: a non-correlation test adopted to the observation conditions and the construction of diagrams (absolute magnitude, volume) using the K-correction deduced from the composite spectrum. This procedure happens to give relatively well-defined values of the parameters; the central values of the density parameter, the reduced curvature and the reduced cosmological constant are: Ω 0 =0.053, k 0 =0.245, lambda-zero=1.19, which correspond to a big bang model, eternally expanding, spatially finite, in which Hubble's parameter H is presently increasing. This model responds well to different cosmological tests: density of matter, diameter of radio sources, age of the universe. Its characteristics suggest various cosmogonic mechanisms, espacially mass formation by growth of empty spherical bubbles [fr
Standard test method for galling resistance of material couples
American Society for Testing and Materials. Philadelphia
2008-01-01
1.1 This test method covers a laboratory test that ranks the galling resistance of material couples using a quantitative measure. Bare metals, alloys, nonmetallic materials, coatings, and surface modified materials may be evaluated by this test method. 1.2 This test method is not designed for evaluating the galling resistance of material couples sliding under lubricated conditions, because galling usually will not occur under lubricated sliding conditions using this test method. 1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
A standard for test reliability in group research.
Ellis, Jules L
2013-03-01
Many authors adhere to the rule that test reliabilities should be at least .70 or .80 in group research. This article introduces a new standard according to which reliabilities can be evaluated. This standard is based on the costs or time of the experiment and of administering the test. For example, if test administration costs are 7 % of the total experimental costs, the efficient value of the reliability is .93. If the actual reliability of a test is equal to this efficient reliability, the test size maximizes the statistical power of the experiment, given the costs. As a standard in experimental research, it is proposed that the reliability of the dependent variable be close to the efficient reliability. Adhering to this standard will enhance the statistical power and reduce the costs of experiments.
Slovak Office of Standards, Metrology and Testing. Annual Report 2001
International Nuclear Information System (INIS)
2002-01-01
A brief account of activities carried out by the Slovak Office of Standards, Metrology and Testing of the Slovak Republic in 2001 is presented. These activities are reported under the headings: (1) Introduction by the President of the Slovak Office of Standards, Metrology and Testing; (2) The Vice-president's Unit Standardization and Quality; (3) The President's Office; (4) Chief Inspector Department; (5) Legislative-juridical Department; (6) Department of Economy; (7) Department of International Co-operation; (8) Department of European Integration; (9) Department of Metrology; (10) Department of Testing; (11) Department of the Cyclotron Centre SR; (12) Slovak Institute of Metrology; (13) Slovak Standards Institution; (14) Slovak Metrology Inspectorate; (15) Slovak Legal Metrology; (16) Measuring Techniques - Technocentre - MTT; Abbreviations; (17) Technical Testing Institute Piestany; (18) Testing Institute of Transport and Earthmoving Machinery - SUDST
Physical and Relativistic Numerical Cosmology.
Anninos, Peter
1998-01-01
In order to account for the observable Universe, any comprehensive theory or model of cosmology must draw from many disciplines of physics, including gauge theories of strong and weak interactions, the hydrodynamics and microphysics of baryonic matter, electromagnetic fields, and spacetime curvature, for example. Although it is difficult to incorporate all these physical elements into a single complete model of our Universe, advances in computing methods and technologies have contributed significantly towards our understanding of cosmological models, the Universe, and astrophysical processes within them. A sample of numerical calculations addressing specific issues in cosmology are reviewed in this article: from the Big Bang singularity dynamics to the fundamental interactions of gravitational waves; from the quark-hadron phase transition to the large scale structure of the Universe. The emphasis, although not exclusively, is on those calculations designed to test different models of cosmology against the observed Universe.
Physical and Relativistic Numerical Cosmology
Directory of Open Access Journals (Sweden)
Peter Anninos
1998-01-01
Full Text Available In order to account for the observable Universe, any comprehensive theory or model of cosmology must draw from many disciplines of physics, including gauge theories of strong and weak interactions, the hydrodynamics and microphysics of baryonic matter, electromagnetic fields, and spacetime curvature, for example. Although it is difficult to incorporate all these physical elements into a single complete model of our Universe, advances in computing methods and technologies have contributed significantly towards our understanding of cosmological models, the Universe, and astrophysical processes within them. A sample of numerical calculations addressing specific issues in cosmology are reviewed in this article: from the Big Bang singularity dynamics to the fundamental interactions of gravitational waves; from the quark--hadron phase transition to the large scale structure of the Universe. The emphasis, although not exclusively, is on those calculations designed to test different models of cosmology against the observed Universe.
Exact solutions in string-motivated scalar-field cosmology
International Nuclear Information System (INIS)
Oezer, M.; Taha, M.O.
1992-01-01
Two exact cosmological solutions to a scalar-field potential motivated by six-dimensional (6D) Einstein-Maxwell theory are given. The resulting pure scalar-field cosmology is free of singularity and causality problems but conserves entropy. These solutions are then extended into exact cosmological solutions for a decaying scalar field with an approximate two-loop 4D string potential. The resulting cosmology is, for both solutions, free of cosmological problems and close to the standard cosmology of the radiation era
Pad-weighing test performed with standardized bladder volume
DEFF Research Database (Denmark)
Lose, G; Rosenkilde, P; Gammelgaard, J
1988-01-01
The result of the one-hour pad-weighing test proposed by the International Continence Society has been demonstrated to depend on the urine load during the test. To increase reproducibility of the pad-weighing test by minimizing the influence of variation in urine load the test was done with a sta...... to +/- 24 g between two tests. It is concluded that this setup (i.e., standardized bladder volume) of the one-hour pad-weighing test allows for a more reliable assessment of urinary incontinence for quantitative purposes....... with a standardized bladder volume (50% of the cystometric bladder capacity). Twenty-five female patients with stress or mixed incontinence underwent two separate tests. Test-retest results were highly correlated (r = 0.97, p less than 0.001). Nonetheless, analysis of test-retest differences revealed a variation up...
International Nuclear Information System (INIS)
Amsterdamski, P.
1986-01-01
The standard cosmological model is reviewed and shown not to be self-sufficient in that it requires initial conditions most likely to be supplied by quantum cosmology. The possible approaches to the issue of initial conditions for cosmology are then discussed. In this thesis, the author considers three separate problems related to this issue. First, the possibility of inflation is investigated in detail by analyzing the evolution of metric perturbations and fluctuations in the expectation value of a scalar field prior to a phase transition; finite temperature effects are also included. Since the inhomogeneities were damped well before the onset of a phase transition. It is concluded that an inflation was possible. Next, the effective action of neutrino and photon fields is calculated for homogeneous spacetimes with small anisotropy; it is shown that quantum corrections to the action due to these fields influence the evolution of an early Universe in the Same way as do the analogous correction terms arising from a conformally invariant scalar which has been previously studied. Finally, the question of an early anisotropy is also discussed in a framework of Hartle-Hawking wave function of the Universe. A wave function of a Bianchi IX type Universe is calculated in a semiclassical approximation
Cosmological perturbations in antigravity
Oltean, Marius; Brandenberger, Robert
2014-10-01
We compute the evolution of cosmological perturbations in a recently proposed Weyl-symmetric theory of two scalar fields with oppositely signed conformal couplings to Einstein gravity. It is motivated from the minimal conformal extension of the standard model, such that one of these scalar fields is the Higgs while the other is a new particle, the dilaton, introduced to make the Higgs mass conformally symmetric. At the background level, the theory admits novel geodesically complete cyclic cosmological solutions characterized by a brief period of repulsive gravity, or "antigravity," during each successive transition from a big crunch to a big bang. For simplicity, we consider scalar perturbations in the absence of anisotropies, with potential set to zero and without any radiation. We show that despite the necessarily wrong-signed kinetic term of the dilaton in the full action, these perturbations are neither ghostlike nor tachyonic in the limit of strongly repulsive gravity. On this basis, we argue—pending a future analysis of vector and tensor perturbations—that, with respect to perturbative stability, the cosmological solutions of this theory are viable.
Scalar-tensor cosmology with cosmological constant
International Nuclear Information System (INIS)
Maslanka, K.
1983-01-01
The equations of scalar-tensor theory of gravitation with cosmological constant in the case of homogeneous and isotropic cosmological model can be reduced to dynamical system of three differential equations with unknown functions H=R/R, THETA=phi/phi, S=e/phi. When new variables are introduced the system becomes more symmetrical and cosmological solutions R(t), phi(t), e(t) are found. It is shown that when cosmological constant is introduced large class of solutions which depend also on Dicke-Brans parameter can be obtained. Investigations of these solutions give general limits for cosmological constant and mean density of matter in plane model. (author)
Topics in inflationary cosmologies
International Nuclear Information System (INIS)
Mahajan, S.
1986-04-01
Several aspects of inflationary cosmologies are discussed. An introduction to the standard hot big bang cosmological model is reviewed, and some of the problems associated with it are presented. A short review of the proposals for solving the cosmological conundrums of the big bang model is presented. Old and the new inflationary scenarios are discussed and shown to be unacceptable. Some alternative scenarios especially those using supersymmetry are reviewed briefly. A study is given of inflationary models where the same set of fields that breaks supersymmetry is also responsible for inflation. In these models, the scale of supersymmetry breaking is related to the slope of the potential near the origin and can thus be kept low. It is found that a supersymmetry breaking scale of the order of the weak breaking scale. The cosmology obtained from the simplest of such models is discussed in detail and it is shown that there are no particular problems except a low reheating temperature and a violation of the thermal constraint. A possible solution to the thermal constraint problem is given by introducing a second field, and the role played by this second field in the scenario is discussed. An alternative mechanism for the generation of baryon number within the framework of supergravity inflationary models is studied using the gravitational couplings of the heavy fields with the hidden sector (the sector which breaks supersymmetry). This mechanism is applied to two specific models - one with and one without supersymmetry breaking. The baryon to entropy ratio is found to be dependent on parameters which are model dependent. Finally, the effect of direct coupling between the two sectors on results is related, 88 refs., 6 figs
Nonlocal teleparallel cosmology.
Bahamonde, Sebastian; Capozziello, Salvatore; Faizal, Mir; Nunes, Rafael C
2017-01-01
Even though it is not possible to differentiate general relativity from teleparallel gravity using classical experiments, it could be possible to discriminate between them by quantum gravitational effects. These effects have motivated the introduction of nonlocal deformations of general relativity, and similar effects are also expected to occur in teleparallel gravity. Here, we study nonlocal deformations of teleparallel gravity along with its cosmological solutions. We observe that nonlocal teleparallel gravity (like nonlocal general relativity) is consistent with the present cosmological data obtained by SNe Ia + BAO + CC + [Formula: see text] observations. Along this track, future experiments probing nonlocal effects could be used to test whether general relativity or teleparallel gravity gives the most consistent picture of gravitational interaction.
Nonlocal teleparallel cosmology
Energy Technology Data Exchange (ETDEWEB)
Bahamonde, Sebastian [University College London, Department of Mathematics, London (United Kingdom); Capozziello, Salvatore [Universita di Napoli ' ' Federico II' ' , Dipartimento di Fisica ' ' E. Pancini' ' , Naples (Italy); Gran Sasso Science Institute, L' Aquila (Italy); Compl. Univ. di Monte S. Angelo, Naples (Italy); INFN, Napoli (Italy); Faizal, Mir [University of British Columbia - Okanagan, Irving K. Barber School of Arts and Sciences, Kelowna, BC (Canada); University of Lethbridge, Department of Physics and Astronomy, Lethbridge, AB (Canada); Nunes, Rafael C. [Universidade Federal de Juiz de Fora, Departamento de Fisica, Juiz de Fora, MG (Brazil)
2017-09-15
Even though it is not possible to differentiate general relativity from teleparallel gravity using classical experiments, it could be possible to discriminate between them by quantum gravitational effects. These effects have motivated the introduction of nonlocal deformations of general relativity, and similar effects are also expected to occur in teleparallel gravity. Here, we study nonlocal deformations of teleparallel gravity along with its cosmological solutions. We observe that nonlocal teleparallel gravity (like nonlocal general relativity) is consistent with the present cosmological data obtained by SNe Ia + BAO + CC + H{sub 0} observations. Along this track, future experiments probing nonlocal effects could be used to test whether general relativity or teleparallel gravity gives the most consistent picture of gravitational interaction. (orig.)
Cosmological implications of light element abundances: theory.
Schramm, D N
1993-06-01
Primordial nucleosynthesis provides (with the microwave background radiation) one of the two quantitative experimental tests of the hot Big Bang cosmological model (versus alternative explanations for the observed Hubble expansion). The standard homogeneous-isotropic calculation fits the light element abundances ranging from 1H at 76% and 4He at 24% by mass through 2H and 3He at parts in 105 down to 7Li at parts in 1010. It is also noted how the recent Large Electron Positron Collider (and Stanford Linear Collider) results on the number of neutrinos (Nnu) are a positive laboratory test of this standard Big Bang scenario. The possible alternate scenario of quark-hadron-induced inhomogeneities is also discussed. It is shown that when this alternative scenario is made to fit the observed abundances accurately, the resulting conclusions on the baryonic density relative to the critical density (Omegab) remain approximately the same as in the standard homogeneous case, thus adding to the robustness of the standard model and the conclusion that Omegab approximately 0.06. This latter point is the driving force behind the need for nonbaryonic dark matter (assuming total density Omegatotal = 1) and the need for dark baryonic matter, since the density of visible matter Omegavisible < Omegab. The recent Population II B and Be observations are also discussed and shown to be a consequence of cosmic ray spallation processes rather than primordial nucleosynthesis. The light elements and Nnu successfully probe the cosmological model at times as early as 1 sec and a temperature (T) of approximately 10(10) K (approximately 1 MeV). Thus, they provided the first quantitative arguments that led to the connections of cosmology to nuclear and particle physics.
International Nuclear Information System (INIS)
Hawking, S.W.
1984-01-01
The subject of these lectures is quantum effects in cosmology. The author deals first with situations in which the gravitational field can be treated as a classical, unquantized background on which the quantum matter fields propagate. This is the case with inflation at the GUT era. Nevertheless the curvature of spacetime can have important effects on the behaviour of the quantum fields and on the development of long-range correlations. He then turns to the question of the quantization of the gravitational field itself. The plan of these lectures is as follows: Euclidean approach to quantum field theory in flat space; the extension of techniques to quantum fields on a curved background with the four-sphere, the Euclidean version of De Sitter space as a particular example; the GUT era; quantization of the gravitational field by Euclidean path integrals; mini superspace model. (Auth.)
Krioukov, Dmitri; Kitsak, Maksim; Sinkovits, Robert S; Rideout, David; Meyer, David; Boguñá, Marián
2012-01-01
Prediction and control of the dynamics of complex networks is a central problem in network science. Structural and dynamical similarities of different real networks suggest that some universal laws might accurately describe the dynamics of these networks, albeit the nature and common origin of such laws remain elusive. Here we show that the causal network representing the large-scale structure of spacetime in our accelerating universe is a power-law graph with strong clustering, similar to many complex networks such as the Internet, social, or biological networks. We prove that this structural similarity is a consequence of the asymptotic equivalence between the large-scale growth dynamics of complex networks and causal networks. This equivalence suggests that unexpectedly similar laws govern the dynamics of complex networks and spacetime in the universe, with implications to network science and cosmology.
Standard test methods for characterizing duplex grain sizes
American Society for Testing and Materials. Philadelphia
2002-01-01
1.1 These test methods provide simple guidelines for deciding whether a duplex grain size exists. The test methods separate duplex grain sizes into one of two distinct classes, then into specific types within those classes, and provide systems for grain size characterization of each type. 1.2 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.3 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety concerns associated with its use. It is the responsibility of the user of this standard to consult appropriate safety and health practices and determine the applicability of regulatory limitations prior to its use.
Brane cosmology in teleparallel and f (T ) gravity
International Nuclear Information System (INIS)
Atazadeh, K; Eghbali, A
2015-01-01
We consider the cosmology of a brane-world scenario in the framework of teleparallel and f(T) gravity in a way that matter is localized on the brane. We show that the cosmology of such branes is different from the standard cosmology in teleparallelism. In particular, we obtain a class of new solutions with a constant five-dimensional radius and cosmologically evolving brane in the context of constant torsion f(T) gravity. (paper)
Cognitive Fatigue Influences Students’ Performance on Standardized Tests
DEFF Research Database (Denmark)
Sievertsen, Hans Henrik; Gino, Francesca; Piovesan, Marco
2016-01-01
We identify one potential source of bias that influences children’s performance on standardized tests and that is predictable based on psychological theory: the time at which students take the test. Using test data for all children attending Danish public schools between school years 2009....../10 and 2012/13, we find that, for every hour later in the day, test scores decrease by 0.9% of an SD. In addition, a 20- to 30-minute break improves average test scores. Time of day affects students’ test performance because, over the course of a regular day, students’ mental resources get taxed. Thus......, as the day wears on, students become increasingly fatigued and consequently more likely to underperform on a standardized test....
Standard practice for conducting atmospheric corrosion tests on metals
American Society for Testing and Materials. Philadelphia
2010-01-01
1.1 This practice covers and defines conditions for exposure of metals and alloys to the weather. It sets forth the general procedures that should be followed in any atmospheric test. It is presented as an aid in conducting atmospheric corrosion tests so that some of the pitfalls of such testing may be avoided. As such, it is concerned mainly with panel exposures to obtain data for comparison purposes. 1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of whoever uses this standard to consult and establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
Simple inflationary models in Gauss–Bonnet brane-world cosmology
International Nuclear Information System (INIS)
Okada, Nobuchika; Okada, Satomi
2016-01-01
In light of the recent Planck 2015 results for the measurement of the cosmic microwave background (CMB) anisotropy, we study simple inflationary models in the context of the Gauss–Bonnet (GB) brane-world cosmology. The brane-world cosmological effect modifies the power spectra of scalar and tensor perturbations generated by inflation and causes a dramatic change for the inflationary predictions of the spectral index ( n s ) and the tensor-to-scalar ratio ( r ) from those obtained in the standard cosmology. In particular, the predicted r values in the inflationary models favored by the Planck 2015 results are suppressed due to the GB brane-world cosmological effect, which is in sharp contrast with inflationary scenario in the Randall–Sundrum brane-world cosmology, where the r values are enhanced. Hence, these two brane-world cosmological scenarios are distinguishable. With the dramatic change of the inflationary predictions, the inflationary scenario in the GB brane-world cosmology can be tested by more precise measurements of n s and future observations of the CMB B -mode polarization. (paper)
Cosmological parameter estimation using Particle Swarm Optimization
Prasad, J.; Souradeep, T.
2014-03-01
Constraining parameters of a theoretical model from observational data is an important exercise in cosmology. There are many theoretically motivated models, which demand greater number of cosmological parameters than the standard model of cosmology uses, and make the problem of parameter estimation challenging. It is a common practice to employ Bayesian formalism for parameter estimation for which, in general, likelihood surface is probed. For the standard cosmological model with six parameters, likelihood surface is quite smooth and does not have local maxima, and sampling based methods like Markov Chain Monte Carlo (MCMC) method are quite successful. However, when there are a large number of parameters or the likelihood surface is not smooth, other methods may be more effective. In this paper, we have demonstrated application of another method inspired from artificial intelligence, called Particle Swarm Optimization (PSO) for estimating cosmological parameters from Cosmic Microwave Background (CMB) data taken from the WMAP satellite.
Cosmological parameter estimation using Particle Swarm Optimization
International Nuclear Information System (INIS)
Prasad, J; Souradeep, T
2014-01-01
Constraining parameters of a theoretical model from observational data is an important exercise in cosmology. There are many theoretically motivated models, which demand greater number of cosmological parameters than the standard model of cosmology uses, and make the problem of parameter estimation challenging. It is a common practice to employ Bayesian formalism for parameter estimation for which, in general, likelihood surface is probed. For the standard cosmological model with six parameters, likelihood surface is quite smooth and does not have local maxima, and sampling based methods like Markov Chain Monte Carlo (MCMC) method are quite successful. However, when there are a large number of parameters or the likelihood surface is not smooth, other methods may be more effective. In this paper, we have demonstrated application of another method inspired from artificial intelligence, called Particle Swarm Optimization (PSO) for estimating cosmological parameters from Cosmic Microwave Background (CMB) data taken from the WMAP satellite
Evaluation of Suitability of Non-Standardized Test Block for Ultrasonic Testing
International Nuclear Information System (INIS)
Kwon, Ho Young; Lim, Jong Ho; Kang, Sei Sun
2000-01-01
Standard Test Block(STB) for UT(Ultrasonic Testing) is a block approved by authoritative for material, shape and quality. STB is used for characteristic tests, sensitivity calibration and control of the time base range of UT inspection devices. The material, size and chemical components of STB should be strictly controlled to meet the related standards such as ASTM and JIS because it has an effect upon sensitivity, resolution and reproductivity of UT. The STBs which are not approved are sometimes used because the qualified STBs are very expensive. So, the purpose of this study is to survey the characteristics, quality and usability of Non-Standardized Test Blocks. Non-Standardized Test Blocks did not meet the standard requirements in size or chemical components, and ultrasonic characteristics. Therefore if the Non-Standardized Test Blocks are used without being tested, it's likely to cause errors in detecting the location and measuring the size of the defects
Standards for Educational and Psychological Testing, 2014 Edition
American Educational Research Association (AERA), 2014
2014-01-01
Developed jointly by the American Educational Research Association, American Psychological Association, and the National Council on Measurement in Education, "Standards for Educational and Psychological Testing" (Revised 2014) addresses professional and technical issues of test development and use in education, psychology, and…
Standard Guide for Conducting Corrosion Tests in Field Applications
American Society for Testing and Materials. Philadelphia
2008-01-01
1.1 This guide covers procedures for conducting corrosion tests in plant equipment or systems under operating conditions to evaluate the corrosion resistance of engineering materials. It does not cover electrochemical methods for determining corrosion rates. 1.1.1 While intended primarily for immersion tests, general guidelines provided can be applicable for exposure of test specimens in plant atmospheres, provided that placement and orientation of the test specimens is non-restrictive to air circulation. 1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. See also 10.4.2.
Sterile neutrino constraints from cosmology
DEFF Research Database (Denmark)
Hamann, Jan; Hannestad, Steen; Raffelt, Georg G.
2012-01-01
The presence of light particles beyond the standard model's three neutrino species can profoundly impact the physics of decoupling and primordial nucleosynthesis. I review the observational signatures of extra light species, present constraints from recent data, and discuss the implications of po...... of possible sterile neutrinos with O(eV)-masses for cosmology....
The Higgs boson and cosmology.
Shaposhnikov, Mikhail
2015-01-13
I will discuss how the Higgs field of the Standard Model may have played an important role in cosmology, leading to the homogeneity, isotropy and flatness of the Universe; producing the quantum fluctuations that seed structure formation; triggering the radiation-dominated era of the hot Big Bang; and contributing to the processes of baryogenesis and dark matter production.
Shaposhnikov, Mikhail
2015-01-01
I will discuss how the Higgs field of the Standard Model may have played an important role in cosmology, leading to the homogeneity, isotropy and flatness of the Universe; producing the quantum fluctuations that seed structure formation; triggering the radiation-dominated era of the hot Big Bang; and contributing to the processes of baryogenesis and dark matter production.
Standard practice for modified salt spray (fog) testing
American Society for Testing and Materials. Philadelphia
2009-01-01
1.1 This practice covers and sets forth conditions for five modifications in salt spray (fog) testing for specification purposes. These are in chronological order of their development: 1.1.1 Annex A1, acetic acid-salt spray test, continuous. 1.1.2 Annex A2, cyclic acidified salt spray test. 1.1.3 Annex A3, seawater acidified test, cyclic (SWAAT). 1.1.4 Annex A4, SO2 salt spray test, cyclic. 1.1.5 Annex A5, dilute electrolyte cyclic fog dry test. 1.2 This practice does not prescribe the type of modification, test specimen or exposure periods to be used for a specific product, nor the interpretation to be given to the results. 1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to consult and establish appropriate safety and health practices and determine the applicabilit...
International Nuclear Information System (INIS)
Meissner, Frank
2008-01-01
This paper describes by means of examples the role of safety standards for radiation protection and the testing and qualification procedures. The development and qualification of radiation protection instrumentation is a significant part of the work of TUV NORD SysTec, an independent expert organisation in Germany. The German Nuclear Safety Standards Commission (KTA) establishes regulations in the field of nuclear safety. The examples presented may be of importance for governments and nuclear safety authorities, for nuclear operators and for manufacturers worldwide. They demonstrate the advantage of standards in the design of radiation protection instrumentation for new power plants, in the upgrade of existing instrumentation to nuclear safety standards or in the application of safety standards to newly developed equipment. Furthermore, they show how authorities may proceed when safety standards for radiation protection instrumentation are not yet established or require actualization. (author)
Tweed, D. P.; Mamon, G. A.; Thuan, T. X.; Cattaneo, A.; Dekel, A.; Menci, N.; Calura, F.; Silk, J.
2018-06-01
In the local Universe, the existence of very young galaxies (VYGs), having formed at least half their stellar mass in the last 1 Gyr, is debated. We predict the present-day fraction of VYGs among central galaxies as a function of galaxy stellar mass. For this, we apply to high mass resolution Monte Carlo halo merger trees (MCHMTs) three (one) analytical models of galaxy formation, where the ratio of stellar to halo mass (mass growth rate) is a function of halo mass and redshift. Galaxy merging is delayed until orbital decay by dynamical friction. With starbursts associated with halo mergers, our models predict typically 1 per cent of VYGs up to galaxy masses of m = 1010 M⊙, falling rapidly at higher masses, and VYGs are usually associated with recent major mergers of their haloes. Without these starbursts, two of the models have VYG fractions reduced by 1 or 2 dex at low or intermediate stellar masses, and VYGs are rarely associated with major halo mergers. In comparison, the state-of-the-art semi-analytical model (SAM) of Henriques et al. produces only 0.01 per cent of VYGs at intermediate masses. Finally, the Menci et al. SAM run on MCHMTs with Warm Dark Matter cosmology generates 10 times more VYGs at m < 108 M⊙ than when run with Cold Dark Matter. The wide range in these VYG fractions illustrates the usefulness of VYGs to constrain both galaxy formation and cosmological models.
Standard Guide for Testing Materials for Aerospace Plastic Transparent Enclosures
American Society for Testing and Materials. Philadelphia
2008-01-01
1.1 This guide is intended to summarize the standard test methods available on individual and composite materials utilized in fabrication of aerospace plastic transparent enclosures. As such, it is intended to specifically include transparent thermoplastics, transparent elastomers, and reinforced plastics, whether thermoplastic or thermosetting. 1.2 This guide is intended as an aid in the search for test methods pertinent to Aerospace Plastic Transparent Enclosures. It should be understood that all methods listed may not apply to all enclosures. 1.3 The standards included refer to the properties or aspects listed in Table 1. The properties or aspects are listed in alphabetical order and the descriptions used are intended to facilitate the search. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limi...
Nonlinear evolution of f(R) cosmologies. I. Methodology
International Nuclear Information System (INIS)
Oyaizu, Hiroaki
2008-01-01
We introduce the method and the implementation of a cosmological simulation of a class of metric-variation f(R) models that accelerate the cosmological expansion without a cosmological constant and evade solar-system bounds of small-field deviations to general relativity. Such simulations are shown to reduce to solving a nonlinear Poisson equation for the scalar degree of freedom introduced by the f(R) modifications. We detail the method to efficiently solve the nonlinear Poisson equation by using a Newton-Gauss-Seidel relaxation scheme coupled with the multigrid method to accelerate the convergence. The simulations are shown to satisfy tests comparing the simulated outcome to analytical solutions for simple situations, and the dynamics of the simulations are tested with orbital and Zeldovich collapse tests. Finally, we present several static and dynamical simulations using realistic cosmological parameters to highlight the differences between standard physics and f(R) physics. In general, we find that the f(R) modifications result in stronger gravitational attraction that enhances the dark matter power spectrum by ∼20% for large but observationally allowed f(R) modifications. A more detailed study of the nonlinear f(R) effects on the power spectrum are presented in a companion paper.
Standard Test Method for Abrasive Wear Resistance of Cemented
American Society for Testing and Materials. Philadelphia
2005-01-01
1.1 This test method covers the determination of abrasive wear resistance of cemented carbides. 1.2 The values stated in inch-pound units are to be regarded as the standard. The SI equivalents of inch-pound units are in parentheses and may be approximate. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
Dimensional cosmological principles
International Nuclear Information System (INIS)
Chi, L.K.
1985-01-01
The dimensional cosmological principles proposed by Wesson require that the density, pressure, and mass of cosmological models be functions of the dimensionless variables which are themselves combinations of the gravitational constant, the speed of light, and the spacetime coordinates. The space coordinate is not the comoving coordinate. In this paper, the dimensional cosmological principle and the dimensional perfect cosmological principle are reformulated by using the comoving coordinate. The dimensional perfect cosmological principle is further modified to allow the possibility that mass creation may occur. Self-similar spacetimes are found to be models obeying the new dimensional cosmological principle
Relic gravitons and viscous cosmologies
International Nuclear Information System (INIS)
Cataldo, Mauricio; Mella, Patricio
2006-01-01
Previously it was shown that there exists a class of viscous cosmological models which violate the dominant energy condition for a limited amount of time after which they are smoothly connected to the ordinary radiation era (which preserves the dominant energy conditions). This violation of the dominant energy condition at an early cosmological epoch may influence the slopes of energy spectra of relic gravitons that might be of experimental relevance. However, the bulk viscosity coefficient of these cosmologies became negative during the ordinary radiation era, and then the entropy of the sources driving the geometry decreases with time. We show that in the presence of viscous sources with a linear barotropic equation of state p=γρ we get viscous cosmological models with positive bulk viscous stress during all their evolution, and hence the matter entropy increases with the expansion time. In other words, in the framework of viscous cosmologies, there exist isotropic models compatible with the standard second law of thermodynamics which also may influence the slopes of energy spectra of relic gravitons
DOE standard: Filter test facility quality program plan
International Nuclear Information System (INIS)
1999-02-01
This standard was developed primarily for application in US Department of Energy programs. It contains specific direction for HEPA filter testing performed at a DOE-accepted HEPA Filter Test Facility (FTF). Beneficial comments (recommendations, additions, deletions) and any pertinent data that may improve this document should be sent to the Office of Nuclear Safety Policy and Standards (EH-31), US Department of Energy, Washington, DC 20585, by letter or by using the self-addressed Document Improvement Proposal form (DOE F 1300.3) appearing at the end of this document
DISCOVERY OF A SUPERCLUSTER AT z ∼ 0.91 AND TESTING THE ΛCDM COSMOLOGICAL MODEL
Energy Technology Data Exchange (ETDEWEB)
Kim, Jae-Woo; Im, Myungshin; Lee, Seong-Kook; Hyun, Minhee; Kim, Dohyeong; Choi, Changsu; Hong, Jueun; Kim, Yongjung; Taak, Yoon Chan; Yoon, Yongmin [Center for the Exploration of the Origin of the universe, Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of); Edge, Alastair C. [Department of Physics, University of Durham, South Road, Durham DH1 3LE (United Kingdom); Jeon, Yiseul; Jun, Hyunsung David; Karouzos, Marios; Kim, Duho [Astronomy Program, FPRD, Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of); Kim, Ji Hoon [Subaru Telescope, National Astronomical Observatory of Japan, 650 North A’ohoku Place, Hilo, HI 96720 (United States); Park, Won-Kee, E-mail: kjw0704@gmail.com, E-mail: mim@astro.snu.ac.kr [Korea Astronomy and Space Science Institute, Daejeon 305-348 (Korea, Republic of)
2016-04-10
The ΛCDM cosmological model successfully reproduces many aspects of the galaxy and structure formation of the universe. However, the growth of large-scale structures (LSSs) in the early universe is not well tested yet with observational data. Here, we have utilized wide and deep optical–near-infrared data in order to search for distant galaxy clusters and superclusters (0.8 < z < 1.2). From the spectroscopic observation with the Inamori Magellan Areal Camera and Spectrograph (IMACS) on the Magellan telescope, three massive clusters at z ∼ 0.91 are confirmed in the SSA22 field. Interestingly, all of them have similar redshifts within Δ z ∼ 0.01 with velocity dispersions ranging from 470 to 1300 km s{sup −1}. Moreover, as the maximum separation is ∼15 Mpc, they compose a supercluster at z ∼ 0.91, meaning that this is one of the most massive superclusters at this redshift to date. The galaxy density map implies that the confirmed clusters are embedded in a larger structure stretching over ∼100 Mpc. ΛCDM models predict about one supercluster like this in our surveyed volume, consistent with our finding so far. However, there are more supercluster candidates in this field, suggesting that additional studies are required to determine if the ΛCDM cosmological model can successfully reproduce the LSSs at high redshift.
Assessing cultural validity in standardized tests in stem education
Gassant, Lunes
This quantitative ex post facto study examined how race and gender, as elements of culture, influence the development of common misconceptions among STEM students. Primary data came from a standardized test: the Digital Logic Concept Inventory (DLCI) developed by Drs. Geoffrey L. Herman, Michael C. Louis, and Craig Zilles from the University of Illinois at Urbana-Champaign. The sample consisted of a cohort of 82 STEM students recruited from three universities in Northern Louisiana. Microsoft Excel and the Statistical Package for the Social Sciences (SPSS) were used for data computation. Two key concepts, several sub concepts, and 19 misconceptions were tested through 11 items in the DLCI. Statistical analyses based on both the Classical Test Theory (Spearman, 1904) and the Item Response Theory (Lord, 1952) yielded similar results: some misconceptions in the DLCI can reliably be predicted by the Race or the Gender of the test taker. The research is significant because it has shown that some misconceptions in a STEM discipline attracted students with similar ethnic backgrounds differently; thus, leading to the existence of some cultural bias in the standardized test. Therefore the study encourages further research in cultural validity in standardized tests. With culturally valid tests, it will be possible to increase the effectiveness of targeted teaching and learning strategies for STEM students from diverse ethnic backgrounds. To some extent, this dissertation has contributed to understanding, better, the gap between high enrollment rates and low graduation rates among African American students and also among other minority students in STEM disciplines.
Similar tests and the standardized log likelihood ratio statistic
DEFF Research Database (Denmark)
Jensen, Jens Ledet
1986-01-01
When testing an affine hypothesis in an exponential family the 'ideal' procedure is to calculate the exact similar test, or an approximation to this, based on the conditional distribution given the minimal sufficient statistic under the null hypothesis. By contrast to this there is a 'primitive......' approach in which the marginal distribution of a test statistic considered and any nuisance parameter appearing in the test statistic is replaced by an estimate. We show here that when using standardized likelihood ratio statistics the 'primitive' procedure is in fact an 'ideal' procedure to order O(n -3...
International Nuclear Information System (INIS)
Kajino, T.; Ichiki, F.K.; Garnavich, P.M.; Mathews, G.J.; Yahiro, M.
2005-01-01
A massive cold dark matter particle is likely to disappear when it is quantized in a Randall-Sundrum noncompact higher dimensional AdS 5 spacetime. To distinguish disappearance of our dark matter particle from the previous decaying particles, we refer to it as disappearing cold dark matter (DCDM). We look for cosmological evidence for this new paradigm and show that this new model is consistent with all data at the 95% C.L., satisfying all sorts of presently available observational constraints from the redshift-luminosity relation of Type Ia supernovae, the mass-to-light ratios of galaxy clusters, and the power spectrum of cosmic microwave background [Phys. Rev. D 68 (2003) 083518
Phase portraits of general f(T) cosmology
Awad, A.; El Hanafy, W.; Nashed, G. G. L.; Saridakis, Emmanuel N.
2018-02-01
We use dynamical system methods to explore the general behaviour of f(T) cosmology. In contrast to the standard applications of dynamical analysis, we present a way to transform the equations into a one-dimensional autonomous system, taking advantage of the crucial property that the torsion scalar in flat FRW geometry is just a function of the Hubble function, thus the field equations include only up to first derivatives of it, and therefore in a general f(T) cosmological scenario every quantity is expressed only in terms of the Hubble function. The great advantage is that for one-dimensional systems it is easy to construct the phase space portraits, and thus extract information and explore in detail the features and possible behaviours of f(T) cosmology. We utilize the phase space portraits and we show that f(T) cosmology can describe the universe evolution in agreement with observations, namely starting from a Big Bang singularity, evolving into the subsequent thermal history and the matter domination, entering into a late-time accelerated expansion, and resulting to the de Sitter phase in the far future. Nevertheless, f(T) cosmology can present a rich class of more exotic behaviours, such as the cosmological bounce and turnaround, the phantom-divide crossing, the Big Brake and the Big Crunch, and it may exhibit various singularities, including the non-harmful ones of type II and type IV. We study the phase space of three specific viable f(T) models offering a complete picture. Moreover, we present a new model of f(T) gravity that can lead to a universe in agreement with observations, free of perturbative instabilities, and applying the Om(z) diagnostic test we confirm that it is in agreement with the combination of SNIa, BAO and CMB data at 1σ confidence level.
International Nuclear Information System (INIS)
Gaisser, T.K.; Shafi, Q.; Barr, S.M.; Seckel, D.; Rusjan, E.; Fletcher, R.S.
1991-01-01
This report discusses research of professor at Bartol research institute in the following general areas: particle phenomenology and non-accelerator physics; particle physics and cosmology; theories with higher symmetry; and particle astrophysics and cosmology
International Nuclear Information System (INIS)
Heller, M.
1985-01-01
Two Friedman's cosmological papers (1922, 1924) and his own interpretation of the obtained results are briefly reviewed. Discussion follows of Friedman's role in the early development of relativistic cosmology. 18 refs. (author)
Simulation-based marginal likelihood for cluster strong lensing cosmology
Killedar, M.; Borgani, S.; Fabjan, D.; Dolag, K.; Granato, G.; Meneghetti, M.; Planelles, S.; Ragone-Figueroa, C.
2018-01-01
Comparisons between observed and predicted strong lensing properties of galaxy clusters have been routinely used to claim either tension or consistency with Λ cold dark matter cosmology. However, standard approaches to such cosmological tests are unable to quantify the preference for one cosmology over another. We advocate approximating the relevant Bayes factor using a marginal likelihood that is based on the following summary statistic: the posterior probability distribution function for the parameters of the scaling relation between Einstein radii and cluster mass, α and β. We demonstrate, for the first time, a method of estimating the marginal likelihood using the X-ray selected z > 0.5 Massive Cluster Survey clusters as a case in point and employing both N-body and hydrodynamic simulations of clusters. We investigate the uncertainty in this estimate and consequential ability to compare competing cosmologies, which arises from incomplete descriptions of baryonic processes, discrepancies in cluster selection criteria, redshift distribution and dynamical state. The relation between triaxial cluster masses at various overdensities provides a promising alternative to the strong lensing test.
Standard Test Method for Thermal Oxidative Resistance of Carbon Fibers
American Society for Testing and Materials. Philadelphia
1982-01-01
1.1 This test method covers the apparatus and procedure for the determination of the weight loss of carbon fibers, exposed to ambient hot air, as a means of characterizing their oxidative resistance. 1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses are mathematical conversions to inch-pound units which are provided for information only and are not considered standard. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard information, see Section 8.
Standardization of food allergen extracts for skin prick test
DEFF Research Database (Denmark)
Skamstrup Hansen, K; Bindslev-Jensen, C; Skov, P S
2001-01-01
The aim of the study was to standardize and evaluate technically optimized food allergen extracts for use in skin prick test (SPT). The standardization procedure comprised 36 allergic histories in 32 food allergic patients with 21 healthy, non-atopic individuals serving as controls. The patients...... had a history of allergic symptoms upon ingestion of either cow's milk (n=3), hen's egg (n=9), wheat (n=4), hazelnut (n=14) or cod (n=6). They also had specific IgE in serum to the food in question and a positive SPT with a fresh preparation of the food. The diagnosis had been confirmed by a double......-blind, placebo-controlled food challenge, except for the hazelnut-allergic patients. The controls were subjected to an open food challenge with all the foods to ensure tolerance. The standardization was performed by means of titrated SPT in accordance with the guidelines on biological standardization from...
Preliminary results of testing bioassay analytical performance standards
International Nuclear Information System (INIS)
Fisher, D.R.; Robinson, A.V.; Hadley, R.T.
1983-08-01
The analytical performance of both in vivo and in vitro bioassay laboratories is being studied to determine the capability of these laboratories to meet the minimum criteria for accuracy and precision specified in the draft ANSI Standard N13.30, Performance Criteria for Radiobioassay. This paper presents preliminary results of the first round of testing
Precision tests of quantum chromodynamics and the standard model
International Nuclear Information System (INIS)
Brodsky, S.J.; Lu, H.J.
1995-06-01
The authors discuss three topics relevant to testing the Standard Model to high precision: commensurate scale relations, which relate observables to each other in perturbation theory without renormalization scale or scheme ambiguity, the relationship of compositeness to anomalous moments, and new methods for measuring the anomalous magnetic and quadrupole moments of the W and Z
Juvenile food limitation in standard tests: a warning to ecotoxicologists.
Zimmer, E.I.; Jager, T.; Ducrot, V.; Kooijman, S.A.L.M.
2012-01-01
Standard ecotoxicological tests are as simple as possible and food sources are mainly chosen for practical reasons. Since some organisms change their food preferences during the life-cycle, they might be food limited at some stage if we do not account for such a switch. As organisms tend to respond
Standardized Testing and School Segregation: Like Tinder for Fire?
Knoester, Matthew; Au, Wayne
2017-01-01
Recent research suggests that high-stakes standardized testing has played a negative role in the segregation of children by race and class in schools. In this article we review research on the overall effects of segregation, the positive and negative aspects of how desegregation plans were carried out following the 1954 Supreme Court decision…
Educators Questioning Timing of State Tests Reflecting Standards
Gewertz, Catherine
2013-01-01
New York is ahead of most states in its work to design detailed curricula and professional development for the common core and to build brand-new tests to reflect them. What's unfolding in the Empire State as a result of that work illustrates the way the common standards can pressure changes in the education landscape, and torque the tensions…
Corporate Schooling Meets Corporate Media: Standards, Testing, and Technophilia
Saltman, Kenneth J.
2016-01-01
Educational publishing corporations and media corporations in the United States have been converging, especially through the promotion of standardization, testing, and for-profit educational technologies. Media and technology companies--including News Corp, Apple, and Microsoft--have significantly expanded their presence in public schools to sell…
Topics in Gravitation and Cosmology
Bahrami Taghanaki, Sina
This thesis is focused on two topics in which relativistic gravitational fields play an important role, namely early Universe cosmology and black hole physics. The theory of cosmic inflation has emerged as the most successful theory of the very early Universe with concrete and verifiable predictions for the properties of anisotropies of the cosmic microwave background radiation and large scale structure. Coalescences of black hole binaries have recently been detected by the Laser Interferometer Gravitational Wave Observatory (LIGO), opening a new arena for observationally testing the dynamics of gravity. In part I of this thesis we explore some modifications to the standard theory of inflation. The main predictions of single field slow-roll inflation have been largely consistent with cosmological observations. However, there remain some aspects of the theory that are not presently well understood. Among these are the somewhat interrelated issues of the choice of initial state for perturbations and the potential imprints of pre-inflationary dynamics. It is well known that a key prediction of the standard theory of inflation, namely the Gaussianity of perturbations, is a consequence of choosing a natural vacuum initial state. In chapter 3, we study the generation and detectability of non-Gaussianities in inflationary scalar perturbations that originate from more general choices of initial state. After that, in chapter 4, we study a simple but predictive model of pre-inflationary dynamics in an attempt to test the robustness of inflationary predictions. We find that significant deviations from the standard predictions are unlikely to result from models in which the inflaton field decouples from the pre-inflationary degrees of freedom prior to freeze-out of the observable modes. In part II we turn to a study of an aspect of the thermodynamics of black holes, a subject which has led to important advances in our understanding of quantum gravity. For objects which
International Nuclear Information System (INIS)
Tayler, R.J.
1983-01-01
The standard model of the hot big bang cosmological theory, which appears to be in agreement, at least qualitatively, with the observed properties of the Universe, assumes that the early Universe was homogeneous and isotropic and that it has been continuously expanding from a state characterized by very high temperature and density, where matter and radiation were to a good approximation in a state of thermodynamic equilibrium. In this standard model, it is assumed that baryon number, charge number and the various lepton numbers are all conserved. Only the baryon number is non-zero and this, expressed as the ratio of the net number of baryons (baryons minus antibaryons) to the number of photons per unit volume is the undefined parameter in the model. The author discusses the importance of knowing how many types of neutrinos there are with regard to the He 4 abundance, and the implication of a small, non-zero neutrino mass. (Auth.)
Roos, Matts
2015-01-01
The Fourth Edition of Introduction to Cosmology provides a concise, authoritative study of cosmology at an introductory level. Starting from elementary principles and the early history of cosmology, the text carefully guides the student on to curved spacetimes, special and general relativity, gravitational lensing, the thermal history of the Universe, and cosmological models, including extended gravity models, black holes and Hawking's recent conjectures on the not-so-black holes.
Particle physics and cosmology
International Nuclear Information System (INIS)
Turner, M.S.; Schramm, D.N.
1985-01-01
During the past year, the research of the members of our group has spanned virtually all the topics at the interface of cosmology and particle physics: inflationary Universe scenarios, astrophysical and cosmological constraints on particle properties, ultra-high energy cosmic ray physics, quantum field theory in curved space-time, cosmology with extra dimensions, superstring cosmology, neutrino astronomy with large, underground detectors, and the formation of structure in the Universe
An improved standard total dose test for CMOS space electronics
International Nuclear Information System (INIS)
Fleetwood, D.M.; Winokur, P.S.; Riewe, L.C.; Pease, R.L.
1989-01-01
The postirradiation response of hardened and commercial CMOS devices is investigated as a function of total dose, dose rate, and annealing time and temperature. Cobalt-60 irradiation at ≅ 200 rad(SiO 2 )/s followed by a 1-week 100 degrees C biased anneal and testing is shown to be an effective screen of hardened devices for space use. However, a similar screen and single-point test performed after Co-60 irradiation and elevated temperature anneal cannot be generally defined for commercial devices. In the absence of detailed knowledge about device and circuit radiation response, a two-point standard test is proposed to ensure space surviability of CMOS circuits: a Co-60 irradiation and test to screen against oxide-trapped charge related failures, and an additional rebound test to screen against interface-trap related failures. Testing implications for bipolar technologies are also discussed
Wang, Chun; Zheng, Yi; Chang, Hua-Hua
2014-01-01
With the advent of web-based technology, online testing is becoming a mainstream mode in large-scale educational assessments. Most online tests are administered continuously in a testing window, which may post test security problems because examinees who take the test earlier may share information with those who take the test later. Researchers have proposed various statistical indices to assess the test security, and one most often used index is the average test-overlap rate, which was further generalized to the item pooling index (Chang & Zhang, 2002, 2003). These indices, however, are all defined as the means (that is, the expected proportion of common items among examinees) and they were originally proposed for computerized adaptive testing (CAT). Recently, multistage testing (MST) has become a popular alternative to CAT. The unique features of MST make it important to report not only the mean, but also the standard deviation (SD) of test overlap rate, as we advocate in this paper. The standard deviation of test overlap rate adds important information to the test security profile, because for the same mean, a large SD reflects that certain groups of examinees share more common items than other groups. In this study, we analytically derived the lower bounds of the SD under MST, with the results under CAT as a benchmark. It is shown that when the mean overlap rate is the same between MST and CAT, the SD of test overlap tends to be larger in MST. A simulation study was conducted to provide empirical evidence. We also compared the security of MST under the single-pool versus the multiple-pool designs; both analytical and simulation studies show that the non-overlapping multiple-pool design will slightly increase the security risk.
Phantom cosmologies and fermions
International Nuclear Information System (INIS)
Chimento, Luis P; Forte, Monica; Devecchi, Fernando P; Kremer, Gilberto M
2008-01-01
Form invariance transformations can be used for constructing phantom cosmologies starting with conventional cosmological models. In this work we reconsider the scalar field case and extend the discussion to fermionic fields, where the 'phantomization' process exhibits a new class of possible accelerated regimes. As an application we analyze the cosmological constant group for a fermionic seed fluid
Particle physics and cosmology
International Nuclear Information System (INIS)
Schramm, D.N.; Turner, M.S.
1982-06-01
work is described in these areas: cosmological baryon production; cosmological production of free quarks and other exotic particle species; the quark-hadron transition in the early universe; astrophysical and cosmological constraints on particle properties; massive neutrinos; phase transitions in the early universe; and astrophysical implications of an axion-like particle
International Nuclear Information System (INIS)
Weinberg, S.
1989-01-01
Cosmological constant problem is discussed. History of the problem is briefly considered. Five different approaches to solution of the problem are described: supersymmetry, supergravity, superstring; anthropic approach; mechamism of lagrangian alignment; modification of gravitation theory and quantum cosmology. It is noted that approach, based on quantum cosmology is the most promising one
. ______________________________________________________________________________________ Nobelist George Smoot to Direct Korean Cosmology Institute Nobel Laureate George Smoot has been appointed director of a new cosmology institute in South Korea that will work closely with the year-old Berkeley the Early Universe (IEU) at EWHA Womans University in Seoul, Korea will provide cosmology education
International Nuclear Information System (INIS)
Davies, P.
1991-01-01
The main concepts of cosmology are discussed, and some of the misconceptions are clarified. The features of big bang cosmology are examined, and it is noted that the existence of the cosmic background radiation provides welcome confirmation of the big bang theory. Calculations of relative abundances of the elements conform with observations, further strengthening the confidence in the basic ideas of big bang cosmology
CERN. Geneva. Audiovisual Unit
2001-01-01
Cosmology and particle physics have enjoyed a useful relationship over the entire histories of both subjects. Today, ideas and techniques in cosmology are frequently used to elucidate and constrain theories of elementary particles. These lectures give an elementary overview of the essential elements of cosmology, which is necessary to understand this relationship.
CERN. Geneva
1999-01-01
Cosmology and particle physics have enjoyed a useful relationship over the entire histories of both subjects. Today, ideas and techniques in cosmology are frequently used to elucidate and constrain theories of elementary particles. These lectures give an elementary overview of the essential elements of cosmology, which is necessary to understand this relationship.
International Nuclear Information System (INIS)
Langer, M.
2007-01-01
This is a very concise introductory lecture to Cosmology. We start by reviewing the basics of homogeneous and isotropic cosmology. We then spend some time on the description of the Cosmic Microwave Background. Finally, a small section is devoted to the discussion of the cosmological constant and of some of the related problems
Testing an extrapolation chamber in computed tomography standard beams
Castro, M. C.; Silva, N. F.; Caldas, L. V. E.
2018-03-01
The computed tomography (CT) is responsible for the highest dose values to the patients. Therefore, the radiation doses in this procedure must be accurate. However, there is no primary standard system for this kind of radiation beam yet. In order to search for a CT primary standard, an extrapolation ionization chamber built at the Calibration Laboratory (LCI) of the Instituto de Pesquisas Energéticas e Nucleares (IPEN), was tested in this work. The results showed to be within the international recommended limits.
Particle physics and cosmology
International Nuclear Information System (INIS)
Kolb, E.W.
1986-10-01
This series of lectures is about the role of particle physics in physical processes that occurred in the very early stages of the bug gang. Of particular interest is the role of particle physics in determining the evolution of the early Universe, and the effect of particle physics on the present structure of the Universe. The use of the big bang as a laboratory for placing limits on new particle physics theories will also be discussed. Section 1 reviews the standard cosmology, including primordial nucleosynthesis. Section 2 reviews the decoupling of weakly interacting particles in the early Universe, and discusses neutrino cosmology and the resulting limits that may be placed on the mass and lifetime of massive neutrinos. Section 3 discusses the evolution of the vacuum through phase transitions in the early Universe and the formation of topological defects in the transitions. Section 4 covers recent work on the generation of the baryon asymmetry by baryon-number violating reactions in Grand Unified Theories, and mentions some recent work on baryon number violation effects at the electroweak transition. Section 5 is devoted to theories of cosmic inflation. Finally, Section 6 is a discussion of the role of extra spatial dimensions in the evolution of the early Universe. 78 refs., 32 figs., 6 tabs
Standard test method for drop-weight tear tests of ferritic steels
American Society for Testing and Materials. Philadelphia
2003-01-01
1.1 This test method covers drop-weight tear tests (DWTT) on ferritic steels with thicknesses between 3.18 and 19.1 mm. 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
Standardized Testing Practices: Effect on Graduation and NCLEX® Pass Rates.
Randolph, Pamela K
The use standardized testing in pre-licensure nursing programs has been accompanied by conflicting reports of effective practices. The purpose of this project was to describe standardized testing practices in one states' nursing programs and discover if the use of a cut score or oversight of remediation had any effect on (a) first time NCLEX® pass rates, (b) on-time graduation (OTG) or (c) the combination of (a) and (b). Administrators of 38 nursing programs in one Southwest state were sent surveys; surveys were returned by 34 programs (89%). Survey responses were compared to each program's NCLEX pass rate and on-time graduation rate; t-tests were conducted for significant differences associated with a required minimum score (cut score) and oversight of remediation. There were no significant differences in NCLEX pass or on-time graduation rates related to establishment of a cut score. There was a significant difference when the NCLEX pass rate and on-time graduation rate were combined (Outcome Index "OI") with significantly higher program outcomes (P=.02.) for programs without cut-scores. There were no differences associated with faculty oversight of remediation. The results of this study do not support establishment of a cut-score when implementing a standardized testing. Copyright © 2016. Published by Elsevier Inc.
Philosophical Roots of Cosmology
Ivanovic, M.
2008-10-01
We shall consider the philosophical roots of cosmology in the earlier Greek philosophy. Our goal is to answer the question: Are earlier Greek theories of pure philosophical-mythological character, as often philosophers cited it, or they have scientific character. On the bases of methodological criteria, we shall contend that the latter is the case. In order to answer the question about contemporary situation of the relation philosophy-cosmology, we shall consider the next question: Is contemporary cosmology completely independent of philosophical conjectures? The answer demands consideration of methodological character about scientific status of contemporary cosmology. We also consider some aspects of the relation contemporary philosophy-cosmology.
Standard Practice for Quality Management Systems for Nondestructive Testing Agencies
American Society for Testing and Materials. Philadelphia
2009-01-01
1.1 This practice covers general requirements for the establishment and maintenance of a quality management system for agencies engaged in nondestructive testing (NDT). 1.2 This practice utilizes criteria contained in Practice E 543. 1.3 This practice utilizes criteria contained in American National Standard ANSI/ISO/ASQ Q9001–2000, Quality management systems—Requirements. 1.4 This practice recognizes the importance of establishing minimum safety criteria. 1.5 The use of SI or inch-pound units, or combinations thereof, will be the responsibility of the technical committee whose standards are referred to in this standard. 1.6 This practice does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this practice to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
Testing of camera performance standards at steady and local overloading
International Nuclear Information System (INIS)
Keszthelyine Landori, S.; Adorjanne Farkas, M.; Csirik, J.
1983-01-01
Camera performance standards are usually given for low count rates and uniform irradiation. A conventional analog gamma camera system (Gamma MB 9100 manufactured under the know-how of Picker DC 4/12 in Hungary) was studied on the basis of the Picker test procedure and the NEMA standard system. Uniformity, linearity, spatial and energy resolution were measured at high count rates and uniform irradiation (steady overloading). Linearity was studied at local overloading. Linearity, spatial and energy resolution were measured by a 1024-channel analyzer-computer system of KFKI, Hungary. The data were evaluated on the basis of NEMA standards, while uniformity was measured by the Gamma data processing system and evaluated by special SEGAMS programs. Performance variations were studied between 7500 cps and 75.000 cps pulse rates. Spatial and energy resolution were influenced strongly, uniformity slightly by pulse rates, while linearity did not change at all. Linearity was not influenced even by local overloading. (author)
Black hole versus cosmological horizon entropy
International Nuclear Information System (INIS)
Davis, Tamara M; Davies, P C W; Lineweaver, Charles H
2003-01-01
The generalized second law of thermodynamics states that entropy always increases when all event horizons are attributed with an entropy proportional to their area. We test the generalized second law by investigating the change in entropy when dust, radiation and black holes cross a cosmological event horizon. We generalize for flat, open and closed Friedmann-Robertson-Walker universes by using numerical calculations to determine the cosmological horizon evolution. In most cases, the loss of entropy from within the cosmological horizon is more than balanced by an increase in cosmological event horizon entropy, maintaining the validity of the generalized second law of thermodynamics. However, an intriguing set of open universe models shows an apparent entropy decrease when black holes disappear over the cosmological event horizon. We anticipate that this apparent violation of the generalized second law will disappear when solutions are available for black holes embedded in arbitrary backgrounds
Standard practice for preparing, cleaning, and evaluating corrosion test specimens
American Society for Testing and Materials. Philadelphia
2003-01-01
1.1 This practice covers suggested procedures for preparing bare, solid metal specimens for tests, for removing corrosion products after the test has been completed, and for evaluating the corrosion damage that has occurred. Emphasis is placed on procedures related to the evaluation of corrosion by mass loss and pitting measurements. (Warning—In many cases the corrosion product on the reactive metals titanium and zirconium is a hard and tightly bonded oxide that defies removal by chemical or ordinary mechanical means. In many such cases, corrosion rates are established by mass gain rather than mass loss.) 1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific precautionary statements, see 1 and 7.2.
The Weighted Airman Promotion System: Standardizing Test Scores
2008-01-01
u th o ri ze d Top 3/E6 ratio, inventory 1401206040 100 70 130 5R 2F 2G 3N 2M 2A 4J 4C 4P 4T 4B 1W 2T 3P 1T 4A 2S 5J 1A 1S1C 6F 4N 7S 4R 4E 1N 3A 3V...System: Standardizing Test Scores AFHRL convened a panel to identify the relevant factors to consider, and then sit as a promotion board and rank...Costs If the Air Force decided to standardize test scores, there would be three basic types of costs: implementation costs, marketing costs, and
Remapping dark matter halo catalogues between cosmological simulations
Mead, A. J.; Peacock, J. A.
2014-05-01
We present and test a method for modifying the catalogue of dark matter haloes produced from a given cosmological simulation, so that it resembles the result of a simulation with an entirely different set of parameters. This extends the method of Angulo & White, which rescales the full particle distribution from a simulation. Working directly with the halo catalogue offers an advantage in speed, and also allows modifications of the internal structure of the haloes to account for non-linear differences between cosmologies. Our method can be used directly on a halo catalogue in a self-contained manner without any additional information about the overall density field; although the large-scale displacement field is required by the method, this can be inferred from the halo catalogue alone. We show proof of concept of our method by rescaling a matter-only simulation with no baryon acoustic oscillation (BAO) features to a more standard Λ cold dark matter model containing a cosmological constant and a BAO signal. In conjunction with the halo occupation approach, this method provides a basis for the rapid generation of mock galaxy samples spanning a wide range of cosmological parameters.
Constraints on cosmological parameters in power-law cosmology
International Nuclear Information System (INIS)
Rani, Sarita; Singh, J.K.; Altaibayeva, A.; Myrzakulov, R.; Shahalam, M.
2015-01-01
In this paper, we examine observational constraints on the power law cosmology; essentially dependent on two parameters H 0 (Hubble constant) and q (deceleration parameter). We investigate the constraints on these parameters using the latest 28 points of H(z) data and 580 points of Union2.1 compilation data and, compare the results with the results of ΛCDM . We also forecast constraints using a simulated data set for the future JDEM, supernovae survey. Our studies give better insight into power law cosmology than the earlier done analysis by Kumar [arXiv:1109.6924] indicating it tuning well with Union2.1 compilation data but not with H(z) data. However, the constraints obtained on i.e. H 0 average and q average using the simulated data set for the future JDEM, supernovae survey are found to be inconsistent with the values obtained from the H(z) and Union2.1 compilation data. We also perform the statefinder analysis and find that the power-law cosmological models approach the standard ΛCDM model as q → −1. Finally, we observe that although the power law cosmology explains several prominent features of evolution of the Universe, it fails in details
International standardization of instruments for neutron irradiation tests
International Nuclear Information System (INIS)
Tanimoto, Masataka; Shibata, Akira; Nakamura, Jinichi; Tsuchiya, Kunihiko; Cho, M.; Lee, C.; Park, S.; Choo, K.
2012-01-01
The JMTR in JAEA and HANARO in KAERI are the foremost testing/research reactors in the world and these are expected to contribute to many nuclear fields. As a part of instrument development in irradiation field, information exchange of instruments started from 2010 under the cooperation agreements between KAERI and JAEA. The instruments developed in JMTR and HANARO are introduced and cooperation experiments as future plan are discussed for international standardization. (author)
Energy Technology Data Exchange (ETDEWEB)
Barbour, J B [Department of Physics and Astronomy, University of Rochester (United States)
2007-02-07
to a far better review article or book on modern cosmology. The doubters' case is threadbare at best, as Alain Blanchard put it rather more politely in his panel contribution. The Burbidges and Halton Arp reiterate the difficulties that these eminent scientists have long had in reconciling certain observations with the standard model. Most workers in the field are aware of their views and find they lack substance, especially Arp's worries about some close coincidences between the observed positions of low-redshift galaxies and high-redshift quasars. Virtually everyone believes that they have no statistical significance. Arp's belief that some quasars have non-cosmological redshifts and are being spewed out of nearby exploding galactic centres raises eyebrows. For me the most worthwhile of the 'rebel' papers is Narlikar's. Its first half is a thought-provoking survey of the many modifications through which the big-bang model has passed. He calls them additions of epicycles and in some cases I think he has a point. But his rival theory seems very far fetched and makes my point about Hamlet's ghost. The steady-state theory just will not die: in 1994, Hoyle, G. Burbidge, and Narlikar published the quasi-steady-state theory (The Astrophysical Journal 410 437) in which the universe expands, not perfectly steadily but 'in mini-creation events at regular intervals and in response the universe oscillates on a short-term period of about 50 Gyr while it also has a steady (exponential) long-term expansion at a characteristic time scale of about 1000 Gyr.' I won't go into details, but this looks like a whopping epicycle on the steady-state model{exclamation_point} Wickramasinghe's paper is on iron whiskers, which have now taken over from standard dust as the agents that must transform starlight into the microwave background. In my view the two best papers in the volume are those of the panellists Alain Blanchard (in favour of
International Nuclear Information System (INIS)
Barbour, J B
2007-01-01
cosmology. The doubters' case is threadbare at best, as Alain Blanchard put it rather more politely in his panel contribution. The Burbidges and Halton Arp reiterate the difficulties that these eminent scientists have long had in reconciling certain observations with the standard model. Most workers in the field are aware of their views and find they lack substance, especially Arp's worries about some close coincidences between the observed positions of low-redshift galaxies and high-redshift quasars. Virtually everyone believes that they have no statistical significance. Arp's belief that some quasars have non-cosmological redshifts and are being spewed out of nearby exploding galactic centres raises eyebrows. For me the most worthwhile of the 'rebel' papers is Narlikar's. Its first half is a thought-provoking survey of the many modifications through which the big-bang model has passed. He calls them additions of epicycles and in some cases I think he has a point. But his rival theory seems very far fetched and makes my point about Hamlet's ghost. The steady-state theory just will not die: in 1994, Hoyle, G. Burbidge, and Narlikar published the quasi-steady-state theory (The Astrophysical Journal 410 437) in which the universe expands, not perfectly steadily but 'in mini-creation events at regular intervals and in response the universe oscillates on a short-term period of about 50 Gyr while it also has a steady (exponential) long-term expansion at a characteristic time scale of about 1000 Gyr.' I won't go into details, but this looks like a whopping epicycle on the steady-state model! Wickramasinghe's paper is on iron whiskers, which have now taken over from standard dust as the agents that must transform starlight into the microwave background. In my view the two best papers in the volume are those of the panellists Alain Blanchard (in favour of the standard model though he has difficulties with X-ray clusters) and the observer Michael Disney, who expresses radical doubts
Standard Waste Box Lid Screw Removal Option Testing
International Nuclear Information System (INIS)
Anast, Kurt Roy
2016-01-01
This report provides results from test work conducted to resolve the removal of screws securing the standard waste box (SWB) lids that hold the remediated nitrate salt (RNS) drums. The test work evaluated equipment and process alternatives for removing the 42 screws that hold the SWB lid in place. The screws were secured with a red Loctite thread locker that makes removal very difficult because the rivets that the screw threads into would slip before the screw could be freed from the rivet, making it impossible to remove the screw and therefore the SWB lid.
Standard Waste Box Lid Screw Removal Option Testing
Energy Technology Data Exchange (ETDEWEB)
Anast, Kurt Roy [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2016-03-11
This report provides results from test work conducted to resolve the removal of screws securing the standard waste box (SWB) lids that hold the remediated nitrate salt (RNS) drums. The test work evaluated equipment and process alternatives for removing the 42 screws that hold the SWB lid in place. The screws were secured with a red Loctite thread locker that makes removal very difficult because the rivets that the screw threads into would slip before the screw could be freed from the rivet, making it impossible to remove the screw and therefore the SWB lid.
Fabrication and Testing of Pyramidal X- Band Standard Horn Antenna
Directory of Open Access Journals (Sweden)
Hasan F. Khazaal
2017-11-01
Full Text Available Standard horn antennas are an important device to evaluate many types of antennas, since they are used as a reference to any type of antennas within the microwave frequency bands. In this project the fabrication process and tests of standard horn antenna operating at X-band frequencies have been proposed. The fabricated antenna passed through multi stages of processing of its parts until assembling the final product. These stages are (milling, bending, fitting and welding. The assembled antenna subjected to two types of tests to evaluate its performance. The first one is the test by two port network analyzer to point out S & Z parameters, input resistance, and the voltage standing wave ratio of the horn, while the second test was done using un-echoic chamber to measure the gain, side lobes level and the half power beam width. The results of testing come nearly as a theoretical value of the most important of antenna parameters, like; gain, side lobe level, -3 dB beam width, return loss and voltage standing wave ratio "VSWR", input Impedance.
Standard Test Method for Normal Spectral Emittance at Elevated Temperatures
American Society for Testing and Materials. Philadelphia
1972-01-01
1.1 This test method describes a highly accurate technique for measuring the normal spectral emittance of electrically conducting materials or materials with electrically conducting substrates, in the temperature range from 600 to 1400 K, and at wavelengths from 1 to 35 μm. 1.2 The test method requires expensive equipment and rather elaborate precautions, but produces data that are accurate to within a few percent. It is suitable for research laboratories where the highest precision and accuracy are desired, but is not recommended for routine production or acceptance testing. However, because of its high accuracy this test method can be used as a referee method to be applied to production and acceptance testing in cases of dispute. 1.3 The values stated in SI units are to be regarded as the standard. The values in parentheses are for information only. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this stan...
Balancing standardized testing with personalized training in surgery
Directory of Open Access Journals (Sweden)
Ahmed A
2016-12-01
Full Text Available Aadil Ahmed, Muhammad Abbas Abid, Nasir I Bhatti Department of Otolaryngology-Head and Neck Surgery, The Johns Hopkins School of Medicine, Baltimore, MD, USA Abstract: Students pursuing a medical career in the US are subject to standardized testing at regular intervals. These standardized tests not only quantify the milestones students have already achieved, but also define the path for future achievements. The purpose of these examinations is to help students become self-directed, lifelong learners – an essential attribute of a medical professional. However, whether preparing for these examinations actually makes students such disciplined learners needs to be examined. Especially during residency training with its limited time and unpredictable exposure, trainees must learn in the most efficient way for their learning styles, and thus develop attributes that will be helpful to them in their medical career. In this review, we propose that a personalized, learner-centered approach tailored to residents’ educational needs and preferences can not only fulfill learning interests and objectives but also serve as a time-efficient and cost-effective approach for graduate medical education. Keywords: standardized testing, personalized training, surgery
LHC, Astrophysics and Cosmology
Directory of Open Access Journals (Sweden)
Giulio Auriemma
2014-12-01
Full Text Available In this paper we discuss the impact on cosmology of recent results obtained by the LHC (Large Hadron Collider experiments in the 2011-2012 runs, respectively at √s = 7 and 8 TeV. The capital achievement of LHC in this period has been the discovery of a spin-0 particle with mass 126 GeV/c2, very similar to the Higgs boson of the Standard Model of Particle Physics. Less exciting, but not less important, negative results of searches for Supersymmetric particles or other exotica in direct production or rare decays are discussed in connection with particles and V.H.E. astronomy searches for Dark Matter.
Hydrogen Field Test Standard: Laboratory and Field Performance
Pope, Jodie G.; Wright, John D.
2015-01-01
The National Institute of Standards and Technology (NIST) developed a prototype field test standard (FTS) that incorporates three test methods that could be used by state weights and measures inspectors to periodically verify the accuracy of retail hydrogen dispensers, much as gasoline dispensers are tested today. The three field test methods are: 1) gravimetric, 2) Pressure, Volume, Temperature (PVT), and 3) master meter. The FTS was tested in NIST's Transient Flow Facility with helium gas and in the field at a hydrogen dispenser location. All three methods agree within 0.57 % and 1.53 % for all test drafts of helium gas in the laboratory setting and of hydrogen gas in the field, respectively. The time required to perform six test drafts is similar for all three methods, ranging from 6 h for the gravimetric and master meter methods to 8 h for the PVT method. The laboratory tests show that 1) it is critical to wait for thermal equilibrium to achieve density measurements in the FTS that meet the desired uncertainty requirements for the PVT and master meter methods; in general, we found a wait time of 20 minutes introduces errors methods, respectively and 2) buoyancy corrections are important for the lowest uncertainty gravimetric measurements. The field tests show that sensor drift can become a largest component of uncertainty that is not present in the laboratory setting. The scale was calibrated after it was set up at the field location. Checks of the calibration throughout testing showed drift of 0.031 %. Calibration of the master meter and the pressure sensors prior to travel to the field location and upon return showed significant drifts in their calibrations; 0.14 % and up to 1.7 %, respectively. This highlights the need for better sensor selection and/or more robust sensor testing prior to putting into field service. All three test methods are capable of being successfully performed in the field and give equivalent answers if proper sensors without drift are
Ultracompact Minihalos as Probes of Inflationary Cosmology.
Aslanyan, Grigor; Price, Layne C; Adams, Jenni; Bringmann, Torsten; Clark, Hamish A; Easther, Richard; Lewis, Geraint F; Scott, Pat
2016-09-30
Cosmological inflation generates primordial density perturbations on all scales, including those far too small to contribute to the cosmic microwave background. At these scales, isolated ultracompact minihalos of dark matter can form well before standard structure formation, if the perturbations have sufficient amplitude. Minihalos affect pulsar timing data and are potentially bright sources of gamma rays. The resulting constraints significantly extend the observable window of inflation in the presence of cold dark matter, coupling two of the key problems in modern cosmology.
Large scale inhomogeneities and the cosmological principle
International Nuclear Information System (INIS)
Lukacs, B.; Meszaros, A.
1984-12-01
The compatibility of cosmologic principles and possible large scale inhomogeneities of the Universe is discussed. It seems that the strongest symmetry principle which is still compatible with reasonable inhomogeneities, is a full conformal symmetry in the 3-space defined by the cosmological velocity field, but even in such a case, the standard model is isolated from the inhomogeneous ones when the whole evolution is considered. (author)
Cosmology and particle physics
International Nuclear Information System (INIS)
Salati, P.
1986-01-01
If the hot Big Bang model is correct, the very early universe provides us with a good laboratory to test our ideas on particle physics. The temperature and the density at that time are so high that each known particle must exist in chemical and in thermal equilibrium with the others. When the universe cools, the particles freeze out, leaving us today with a cosmic background. Such a kind of relic is of great interest because we can probe the Big Bang Model by studying the fossilized gas of a known particle. Conversely we can use that model to derive information about a hypothetical particle. Basically the freezing of a gas occurs a temperature T o and may be thermal or chemical. Studying the decoupling of a stable neutrino brings information on its mass: if the mass M ν lies in the forbidden range, the neutrino has to be unstable and its lifetime is constrained by cosmology. As for the G.U.T. Monopole, cosmology tells us that its present mass density is either to big or to small (1 monopole/observable universe) owing to a predicted flux far from the Parker Limit. Finally, the super red-giant star life time constrains the axion or the Higgs to be more massive than .2 MeV [fr
NedWind 25 Blade Testing at NREL for the European Standards Measurement and Testing Program
Energy Technology Data Exchange (ETDEWEB)
Larwood, S.; Musial, W.; Freebury, G.; Beattie, A.G.
2001-04-19
In the mid-90s the European community initiated the Standards, Measurements, and Testing (SMT) program to harmonize testing and measurement procedures in several industries. Within the program, a project was carried out called the European Wind Turbine Testing Procedure Development. The second part of that project, called Blade Test Methods and Techniques, included the United States and was devised to help blade-testing laboratories harmonize their testing methods. This report provides the results of those tests conducted by the National Renewable Energy Laboratory.
Standard practice for conducting moist SO2 tests
American Society for Testing and Materials. Philadelphia
2002-01-01
1.1 This practice covers the apparatus and procedure to be used in conducting qualitative assessment tests in accordance with the requirements of material or product specifications by means of specimen exposure to condensed moisture containing sulfur dioxide. 1.2 The exposure conditions may be varied to suit particular requirements and this practice includes provisions for use of different concentrations of sulfur dioxide and for tests either running continuously or in cycles of alternate exposure to the sulfur dioxide containing atmosphere and to the ambient atmosphere. 1.3 The variant of the test to be used, the exposure period required, the type of test specimen, and the criteria of failure are not prescribed by this practice. Such details are provided in appropriate material and product purchase specifications. 1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. 1.5 This standard does not purport to address all of the safety c...
CERN. Geneva
2014-01-01
We discuss a corpuscular resolution of inflation. In our treatment, the geometric background is viewed as a composite entity, a type of a coherent state, of the constituent gravitons and inflatons. We show that this picture accounts for all the known semi-classical results, but more importantly predicts new quantum effects that are unaccounted neither by standard loop correction nor by known semi-classical non-perturbative effects. These new effects have important consequences. For example, they place an upper bound on the duration of inflation, which is in conflict with the possibility of self-reproduction and eternal inflation. We discuss various implications of these new quantum phenomena.
Directory of Open Access Journals (Sweden)
Ezgi MOR DİRLİK
2017-12-01
Full Text Available The purpose of this research is to analyze four psychological tests which are frequently used in the Guidance and Research Centers and in the guidance services of the schools according to the standards for educational and psychological testing of APA (American Psychological Association and test adaption standards of ITC (International Testing Commission. The tests were determined based on the goal- oriented sample selecting method and were selected from the most frequently used psychological tests in Guidance and Research Centers and school’s guidance centers. These tests are: Scale of Academic Self-Concept (Akademik Benlik Kavramı Ölçeği-ABKÖ, Evaluation of Early Childhood Development Tool (Gazi Erken Çocukluk Gelişimi Değerlendirme Aracı-GEÇDA, Primary Mental Abilities 7-11 (TKT 7-11, and Wechsler Intelligence Scale for Children Revised Form (WISC-R. In this research, the chapters related to the validity, reliability and test development and revision of “Standards For Educational And Psychological Testing” (APA, 1999 and the adaptation standards developed by ITC were translated into Turkish and a checklist was created by using these documents. The checklist has got two forms as short and long form. The tests were analyzed according to the short form of the checklist by researcher. In order to examine the reliability of these analyses, the analyses were repeated in three weeks’ time. Data of these analyses were exported to the Statistical Package for Social Sciences (SPSS 20.0 and descriptive analysis was perfomed. As a result of this research, the meeting levels of the psychological tests to the test standards in the checklist and the features of the tests which should be improved according to the validity, reliability, test development and revision and test adaptation were determined. In conclusion, the standards analyzed have not been met satisfactorily by ABKÖ and GEÇDA, and according to the analyses of the realibility
The Standard-Model Extension and Gravitational Tests
Directory of Open Access Journals (Sweden)
Jay D. Tasson
2016-10-01
Full Text Available The Standard-Model Extension (SME provides a comprehensive effective field-theory framework for the study of CPT and Lorentz symmetry. This work reviews the structure and philosophy of the SME and provides some intuitive examples of symmetry violation. The results of recent gravitational tests performed within the SME are summarized including analysis of results from the Laser Interferometer Gravitational-Wave Observatory (LIGO, sensitivities achieved in short-range gravity experiments, constraints from cosmic-ray data, and results achieved by studying planetary ephemerids. Some proposals and ongoing efforts will also be considered including gravimeter tests, tests of the Weak Equivalence Principle, and antimatter experiments. Our review of the above topics is augmented by several original extensions of the relevant work. We present new examples of symmetry violation in the SME and use the cosmic-ray analysis to place first-ever constraints on 81 additional operators.
Particle cosmology comes of age
International Nuclear Information System (INIS)
Turner, M.S.
1988-01-01
The application of modern ideas in particle physics to astrophysical and cosmological settings is a continuation of a fruitful tradition in astrophysics which began with the application of atomic physics, and then nuclear physics. In the past decade particle cosmology and particle astrophysics have been recognized as 'legitimate activities' by both particle physicists and astrophysicists and astronomers. During this time there has been a high level of theoretical activity producing much speculation about the earliest history of the Universe, as well as important and interesting astrophysical and cosmological constraints to particle physics theories. This period of intense theoretical activity has produced a number of ideas most worthy of careful consideration and scrutiny, and even more importantly, amenable to experimental/observational test. Among the ideas which are likely to be tested in the next decade are: the cosmological bound to the number of neutrino flavors, inflation, relic WIMPs as the dark matter, and MSW neutrino oscillations as a solution to the solar neutrino problems. (orig.)
Particle cosmology comes of age
International Nuclear Information System (INIS)
Turner, M.S.
1987-12-01
The application of modern ideas in particle physics to astrophysical and cosmological settings is a continuation of a fruitful tradition in astrophysics which began with the application of atomic physics, and then nuclear physics. In the past decade particle cosmology and particle astrophysics have been recognized as 'legitimate activities' by both particle physicists and astrophysicists and astronomers. During this time there has been a high level of theoretical activity producing much speculation about the earliest history of the Universe, as well as important and interesting astrophysical and cosmological constraints to particle physics theories. This period of intense theoretical activity has produced a number of ideas most worthy of careful consideration and scrutiny, and even more importantly, amenable to experimental/observational test. Among the ideas which are likely to be tested in the next decade are: the cosmological bound to the number of neutrino flavors, inflation, relic WIMPs as the dark matter, and MSW neutrino oscillations as a solution to the solar neutrino problems. 94 refs
Energy Technology Data Exchange (ETDEWEB)
Verde, Licia; Jimenez, Raul [Institute of Cosmos Sciences, University of Barcelona, IEEC-UB, Martí Franquès, 1, E08028 Barcelona (Spain); Bellini, Emilio [University of Oxford, Denys Wilkinson Building, Keble Road, Oxford, OX1 3RH (United Kingdom); Pigozzo, Cassio [Instituto de Física, Universidade Federal da Bahia, Salvador, BA (Brazil); Heavens, Alan F., E-mail: liciaverde@icc.ub.edu, E-mail: emilio.bellini@physics.ox.ac.uk, E-mail: cpigozzo@ufba.br, E-mail: a.heavens@imperial.ac.uk, E-mail: raul.jimenez@icc.ub.edu [Imperial Centre for Inference and Cosmology (ICIC), Imperial College, Blackett Laboratory, Prince Consort Road, London SW7 2AZ (United Kingdom)
2017-04-01
We investigate our knowledge of early universe cosmology by exploring how much additional energy density can be placed in different components beyond those in the ΛCDM model. To do this we use a method to separate early- and late-universe information enclosed in observational data, thus markedly reducing the model-dependency of the conclusions. We find that the 95% credibility regions for extra energy components of the early universe at recombination are: non-accelerating additional fluid density parameter Ω{sub MR} < 0.006 and extra radiation parameterised as extra effective neutrino species 2.3 < N {sub eff} < 3.2 when imposing flatness. Our constraints thus show that even when analyzing the data in this largely model-independent way, the possibility of hiding extra energy components beyond ΛCDM in the early universe is seriously constrained by current observations. We also find that the standard ruler, the sound horizon at radiation drag, can be well determined in a way that does not depend on late-time Universe assumptions, but depends strongly on early-time physics and in particular on additional components that behave like radiation. We find that the standard ruler length determined in this way is r {sub s} = 147.4 ± 0.7 Mpc if the radiation and neutrino components are standard, but the uncertainty increases by an order of magnitude when non-standard dark radiation components are allowed, to r {sub s} = 150 ± 5 Mpc.
Observational constraints on undulant cosmologies
Energy Technology Data Exchange (ETDEWEB)
Barenboim, Gabriela; /Valencia U.; Mena Requejo, Olga; Quigg, Chris; /Fermilab
2005-10-01
In an undulant universe, cosmic expansion is characterized by alternating periods of acceleration and deceleration. We examine cosmologies in which the dark-energy equation of state varies periodically with the number of e-foldings of the scale factor of the universe, and use observations to constrain the frequency of oscillation. We find a tension between a forceful response to the cosmic coincidence problem and the standard treatment of structure formation.
International Nuclear Information System (INIS)
Debney, G.; Farnsworth, D.
1983-01-01
Motivated by the fact that 2m/r is of the order of magnitude unity for the observable universe, we explore the possibility that a Schwarzschild or black hole cosmological model is appropriate. Luminosity distance and frequency shifts of freely-falling, standard, monochromatic objects are viewed by a freely-falling observer. The observer is inside r=2m. The observer in such a world does not see the same universe as do astronomers. (author)
Standard Test Method for Wet Insulation Integrity Testing of Photovoltaic Arrays
American Society for Testing and Materials. Philadelphia
2010-01-01
1.1 This test method covers a procedure to determine the insulation resistance of a photovoltaic (PV) array (or its component strings), that is, the electrical resistance between the array's internal electrical components and is exposed, electrically conductive, non-current carrying parts and surfaces of the array. 1.2 This test method does not establish pass or fail levels. The determination of acceptable or unacceptable results is beyond the scope of this test method. 1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
Extending cosmology: the metric approach
Mendoza, S.
2012-01-01
Comment: 2012, Extending Cosmology: The Metric Approach, Open Questions in Cosmology; Review article for an Intech "Open questions in cosmology" book chapter (19 pages, 3 figures). Available from: http://www.intechopen.com/books/open-questions-in-cosmology/extending-cosmology-the-metric-approach
Standard practice for torque calibration of testing machines and devices
American Society for Testing and Materials. Philadelphia
2009-01-01
1.1 This practice covers procedures and requirements for the calibration of torque for static and quasi-static torque capable testing machines or devices. These may, or may not, have torque indicating systems and include those devices used for the calibration of hand torque tools. Testing machines may be calibrated by one of the three following methods or combination thereof: 1.1.1 Use of standard weights and lever arms. 1.1.2 Use of elastic torque measuring devices. 1.1.3 Use of elastic force measuring devices and lever arms. 1.1.4 Any of the methods require a specific uncertainty of measurement and a traceability derived from national standards of mass and length. 1.2 The procedures of 1.1.1, 1.1.2, and 1.1.3 apply to the calibration of the torque-indicating systems associated with the testing machine, such as a scale, dial, marked or unmarked recorder chart, digital display, etc. In all cases the buyer/owner/user must designate the torque-indicating system(s) to be calibrated and included in the repor...
Directory of Open Access Journals (Sweden)
Gorbunov Dmitry
2017-01-01
Full Text Available The very well known example of cosmology testing particle physics is the number of relativistic particles (photons and three active neutrinos within the Standard Model at primordial nucleosynthesis. These days the earliest moment we can hope to probe with present cosmological data is the early time inflation. The particle physics conditions there and now are different because of different energy scales and different values of the scalar fields, that usually prohibits a reliable connection between the particle physics parameters at the two interesting epochs. The physics at the highest energy scales may be probed with observations at the largest spatial scales (just somewhat smaller than the size of the visible Universe. However, we are not (yet ready to make the tests realistic, because of lack of a self-consistent theoretical description of the presently favorite cosmological models to be valid right after inflation.
Cao, Shuo; Zheng, Xiaogang; Biesiada, Marek; Qi, Jingzhao; Chen, Yun; Zhu, Zong-Hong
2017-09-01
Context. Ultra-compact structure in radio sources (especially in quasars that can be observed up to very high redshifts), with milliarcsecond angular sizes measured by very-long-baseline interferometry (VLBI), is becoming an important astrophysical tool for probing both cosmology and the physical properties of AGN. Aims: We present a newly compiled data set of 120 milliarcsec. compact radio sources representing intermediate-luminosity quasars covering the redshift range 0.46 RDE) or the Dvali-Gabadadze-Porrati (DGP) brane-world scenario. While no significant change in w with redshift is detected, there is still considerable room for evolution in w and the transition redshift at which w departing from -1 is located at z 2.0. Our results demonstrate that the method extensively investigated in our work on observational radio quasar data can be used to effectively derive cosmological information. Finally, we find the combination of high-redshift quasars and low-redshift clusters may provide an important source of angular diameter distances, considering the redshift coverage of these two astrophysical probes.
Validity and Reliability of Baseline Testing in a Standardized Environment.
Higgins, Kathryn L; Caze, Todd; Maerlender, Arthur
2017-08-11
The Immediate Postconcussion Assessment and Cognitive Testing (ImPACT) is a computerized neuropsychological test battery commonly used to determine cognitive recovery from concussion based on comparing post-injury scores to baseline scores. This model is based on the premise that ImPACT baseline test scores are a valid and reliable measure of optimal cognitive function at baseline. Growing evidence suggests that this premise may not be accurate and a large contributor to invalid and unreliable baseline test scores may be the protocol and environment in which baseline tests are administered. This study examined the effects of a standardized environment and administration protocol on the reliability and performance validity of athletes' baseline test scores on ImPACT by comparing scores obtained in two different group-testing settings. Three hundred-sixty one Division 1 cohort-matched collegiate athletes' baseline data were assessed using a variety of indicators of potential performance invalidity; internal reliability was also examined. Thirty-one to thirty-nine percent of the baseline cases had at least one indicator of low performance validity, but there were no significant differences in validity indicators based on environment in which the testing was conducted. Internal consistency reliability scores were in the acceptable to good range, with no significant differences between administration conditions. These results suggest that athletes may be reliably performing at levels lower than their best effort would produce. © The Author 2017. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
Alternate performance standard project: Interpreting the post-construction test
International Nuclear Information System (INIS)
Williamson, A.D.; McDonough, S.E.
1993-01-01
The paper describes the results of a project commissioned by the State of Florida, in cooperation with the US Environmental Protection Agency, as one portion of the Florida Radon Research Program (FRRP). The purpose of the FRRP is to provide technical support for a statewide Building Standard for Radon-Resistant Construction currently in the rulemaking process. In this case the information provides technical background for a post-construction radon test specified as a performance element of the code which accompanies the prescriptive alternative that does not incorporate active radon reduction systems
Standard test method for measuring pH of soil for use in corrosion testing
American Society for Testing and Materials. Philadelphia
1995-01-01
1.1 This test method covers a procedure for determining the pH of a soil in corrosion testing. The principle use of the test is to supplement soil resistivity measurements and thereby identify conditions under which the corrosion of metals in soil may be accentuated (see G 57 - 78 (1984)). 1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
Standard Specification for Solar Simulation for Terrestrial Photovoltaic Testing
American Society for Testing and Materials. Philadelphia
2010-01-01
1.1 This specification provides means for classifying solar simulators intended for indoor testing of photovoltaic devices (solar cells or modules), according to their spectral match to a reference spectral irradiance, non-uniformity of spatial irradiance, and temporal instability of irradiance. 1.2 Testing of photovoltaic devices may require the use of solar simulators. Test Methods that require specific classification of simulators as defined in this specification include Test Methods E948, E1036, and E1362. 1.3 This standard is applicable to both pulsed and steady state simulators and includes recommended test requirements used for classifying such simulators. 1.4 A solar simulator usually consists of three major components: (1) light source(s) and associated power supply; (2) any optics and filters required to modify the output beam to meet the classification requirements in Section 4; and (3) the necessary controls to operate the simulator, adjust irradiance, etc. 1.5 A light source that does not mee...
Directory of Open Access Journals (Sweden)
Balbi Amedeo
2013-09-01
Full Text Available Time has always played a crucial role in cosmology. I review some of the aspects of the present cosmological model which are more directly related to time, such as: the definition of a cosmic time; the existence of typical timescales and epochs in an expanding universe; the problem of the initial singularity and the origin of time; the cosmological arrow of time.
Inflation and quantum cosmology
International Nuclear Information System (INIS)
Linde, A.
1991-01-01
In this article a review of the present status of inflationary cosmology is given. We start with a discussion of the simplest version of the chaotic inflation scenario. Then we discuss some recent develoments in the inflationary cosmology, including the theory of a self-reproducing inflationary universe (eternal chaotic inflation). We do it with the help of stochastic approach to inflation. The results obtained within this approach are compared with the results obtained in the context of Euclidean quantum cosmology. (WL)
International Nuclear Information System (INIS)
Surdin, M.
1980-01-01
It is shown that viewed from the 'outside', our universe is a black hole. Hence the 'inside' cosmology considered is termed as the Bright Universe Cosmology. The model proposed avoids the singularities of cosmologies of the Big Bang variety, it gives a good account of the redshifts, the cosmic background radiation, the number counts; it also gives a satisfactory explanation of the 'large numbers coincidence' and of the variation in time of fundamental constants. (Auth.)
Filtration: Novel Absorber Evaluation Club aims at standardized testing
International Nuclear Information System (INIS)
Anon.
1990-01-01
In the past few years a number of novel absorber materials, both organic and inorganic, have appeared on the market - some claiming to achieve very large decontamination factors for metal ions, including those having radioactive isotopes. Several of these materials have been tested by individual companies in the nuclear industry and some have shown promise as decontaminants for radioactive waste streams. Unfortunately, the results obtained for the treatment of a particular waste stream cannot be applied directly to the many and diverse waste streams generated throughout the nuclear industry. A unified and standardized testing programme making use of available expertise is necessary to provide a fair and meaningful comparison. In November 1988, representatives of the United Kingdom nuclear industry agreed to form the Novel Absorber Evaluation Club to assess absorber materials and to undertake the necessary work to identify the extent and rate of adsorption of radionuclides by such materials from a set of typical reference waste streams. (author)
Creation-field cosmology: A possible solution to singularity, horizon, and flatness problems
International Nuclear Information System (INIS)
Narlikar, J.V.; Padmanabhan, T.
1985-01-01
A solution of Einstein's equations which admits radiation and a negative-energy massless scalar creation field as a source is presented. It is shown that the cosmological model based on this solution satisfies all the observational tests and thus is a viable alternative to the standard big-bang model. The present model is free from singularity and particle horizon and provides a natural explanation for the flatness problem. We argue that these features make the creation-field cosmological model theoretically superior to the big-bang model
International Nuclear Information System (INIS)
Feng, Jonathan L.
2005-01-01
Cosmology now provides unambiguous, quantitative evidence for new particle physics. I discuss the implications of cosmology for supersymmetry and vice versa. Topics include: motivations for supersymmetry; supersymmetry breaking; dark energy; freeze out and WIMPs; neutralino dark matter; cosmologically preferred regions of minimal supergravity; direct and indirect detection of neutralinos; the DAMA and HEAT signals; inflation and reheating; gravitino dark matter; Big Bang nucleosynthesis; and the cosmic microwave background. I conclude with speculations about the prospects for a microscopic description of the dark universe, stressing the necessity of diverse experiments on both sides of the particle physics/cosmology interface
Roos, Matts
2003-01-01
The Third Edition of the hugely successful Introduction to Cosmology provides a concise, authoritative study of cosmology at an introductory level. Starting from elementary principles and the history of cosmology, the text carefully guides the student on to curved spacetimes, general relativity, black holes, cosmological models, particles and symmetries, and phase transitions. Extensively revised, this latest edition includes broader and updated coverage of distance measures, gravitational lensing and waves, dark energy and quintessence, the thermal history of the Universe, inflation,
Axions in inflationary cosmology
International Nuclear Information System (INIS)
Linde, A.
1991-01-01
The problem of the cosmological constraints on the axion mass is re-examined. It is argued that in the context of inflationary cosmology the constraint m a > or approx.10 -5 eV can be avoided even when the axion perturbations produced during inflation are taken into account. It is shown also that in most axion models the effective parameter f a rapidly changes during inflation. This modifies some earlier statements concerning isothermal perturbations in the axion cosmology. A hybrid inflation scenario is proposed which combines some advantages of chaotic inflation with specific features of new and/or extended inflation. Its implications for the axion cosmology are discussed. (orig.)
Integrated cosmological probes: concordance quantified
Energy Technology Data Exchange (ETDEWEB)
Nicola, Andrina; Amara, Adam; Refregier, Alexandre, E-mail: andrina.nicola@phys.ethz.ch, E-mail: adam.amara@phys.ethz.ch, E-mail: alexandre.refregier@phys.ethz.ch [Department of Physics, ETH Zürich, Wolfgang-Pauli-Strasse 27, CH-8093 Zürich (Switzerland)
2017-10-01
Assessing the consistency of parameter constraints derived from different cosmological probes is an important way to test the validity of the underlying cosmological model. In an earlier work [1], we computed constraints on cosmological parameters for ΛCDM from an integrated analysis of CMB temperature anisotropies and CMB lensing from Planck, galaxy clustering and weak lensing from SDSS, weak lensing from DES SV as well as Type Ia supernovae and Hubble parameter measurements. In this work, we extend this analysis and quantify the concordance between the derived constraints and those derived by the Planck Collaboration as well as WMAP9, SPT and ACT. As a measure for consistency, we use the Surprise statistic [2], which is based on the relative entropy. In the framework of a flat ΛCDM cosmological model, we find all data sets to be consistent with one another at a level of less than 1σ. We highlight that the relative entropy is sensitive to inconsistencies in the models that are used in different parts of the analysis. In particular, inconsistent assumptions for the neutrino mass break its invariance on the parameter choice. When consistent model assumptions are used, the data sets considered in this work all agree with each other and ΛCDM, without evidence for tensions.
Stress-testing the Standard Model at the LHC
2016-01-01
With the high-energy run of the LHC now underway, and clear manifestations of beyond-Standard-Model physics not yet seen in data from the previous run, the search for new physics at the LHC may be a quest for small deviations with big consequences. If clear signals are present, precise predictions and measurements will again be crucial for extracting the maximum information from the data, as in the case of the Higgs boson. Precision will therefore remain a key theme for particle physics research in the coming years. The conference will provide a forum for experimentalists and theorists to identify the challenges and refine the tools for high-precision tests of the Standard Model and searches for signals of new physics at Run II of the LHC. Topics to be discussed include: pinning down Standard Model corrections to key LHC processes; combining fixed-order QCD calculations with all-order resummations and parton showers; new developments in jet physics concerning jet substructure, associated jets and boosted je...
Cosmological and supernova neutrinos
Kajino, T.; Aoki, W.; Balantekin, A. B.; Cheoun, M.-K.; Hayakawa, T.; Hidaka, J.; Hirai, Y.; Kusakabe, M.; Mathews, G. J.; Nakamura, K.; Pehlivan, Y.; Shibagaki, S.; Suzuki, T.
2014-06-01
The Big Bang nucleosynthesis (BBN) and the cosmic microwave background (CMB) anisotropies are the pillars of modern cosmology. It has recently been suggested that axion which is a dark matter candidate in the framework of the standard model could condensate in the early universe and induce photon cooling before the epoch of the photon last scattering. Although this may render a solution to the overproduction problem of primordial 7Li abundance, there arises another serious difficulty of overproducing D abundance. We propose a hybrid dark matter model with both axions and relic supersymmetric (SUSY) particles to solve both overproduction problems of the primordial D and 7Li abundances simultaneously. The BBN also serves to constrain the nature of neutrinos. Considering non-thermal photons produced in the decay of the heavy sterile neutrinos due to the magnetic moment, we explore the cosmological constraint on the strength of neutrino magnetic moment consistent with the observed light element abundances. Core-collapse supernovae eject huge flux of energetic neutrinos which affect explosive nucleosynthesis of rare isotopes like 7Li, 11B, 92Nb, 138La and 180Ta and r-process elements. Several isotopes depend strongly on the neutrino flavor oscillation due to the Mikheyev-Smirnov-Wolfenstein (MSW) effect. Combining the recent experimental constraints on θ13 with predicted and observed supernova-produced abundance ratio 11B/7Li encapsulated in the presolar grains from the Murchison meteorite, we show a marginal preference for an inverted neutrino mass hierarchy. We also discuss supernova relic neutrinos (SRN) that may indicate the softness of the equation of state (EoS) of nuclear matter and adiabatic conditions of the neutrino oscillation.
Cosmological and supernova neutrinos
Energy Technology Data Exchange (ETDEWEB)
Kajino, T. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan Department of Astronomy, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033 (Japan); Aoki, W. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Balantekin, A. B. [Department of Physics, University of Wisconsin - Madison, Wisconsin 53706 (United States); Cheoun, M.-K. [Department of Physics, Soongsil University, Seoul 156-743 (Korea, Republic of); Hayakawa, T. [Japan Atomic Energy Agency, Shirakara-Shirane 2-4, Tokai-mura, Ibaraki 319-1195 (Japan); Hidaka, J. [National Astronomical Observatory, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Hirai, Y.; Shibagaki, S. [National Astronomical Observatory, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan and Department of Astronomy, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033 (Japan); Kusakabe, M. [School of Liberal Arts and Science, Korea Aerospace University, Goyang 412-791 (Korea, Republic of); Mathews, G. J. [Department of Physics, University of Notre Dame, IN 46556 (United States); Nakamura, K. [Waseda University, Ohkubo 3-4-1, Shinjuku, Tokyo 169-8555 (Japan); Pehlivan, Y. [Mimar Sinan GSÜ, Department of Physics, Şişli, İstanbul 34380 (Turkey); Suzuki, T. [Nihon University, Sakurajosui 3-25-40, Setagaya-ku, Tokyo 156-8550 (Japan)
2014-06-24
The Big Bang nucleosynthesis (BBN) and the cosmic microwave background (CMB) anisotropies are the pillars of modern cosmology. It has recently been suggested that axion which is a dark matter candidate in the framework of the standard model could condensate in the early universe and induce photon cooling before the epoch of the photon last scattering. Although this may render a solution to the overproduction problem of primordial {sup 7}Li abundance, there arises another serious difficulty of overproducing D abundance. We propose a hybrid dark matter model with both axions and relic supersymmetric (SUSY) particles to solve both overproduction problems of the primordial D and {sup 7}Li abundances simultaneously. The BBN also serves to constrain the nature of neutrinos. Considering non-thermal photons produced in the decay of the heavy sterile neutrinos due to the magnetic moment, we explore the cosmological constraint on the strength of neutrino magnetic moment consistent with the observed light element abundances. Core-collapse supernovae eject huge flux of energetic neutrinos which affect explosive nucleosynthesis of rare isotopes like {sup 7}Li, {sup 11}B, {sup 92}Nb, {sup 138}La and {sup 180}Ta and r-process elements. Several isotopes depend strongly on the neutrino flavor oscillation due to the Mikheyev-Smirnov-Wolfenstein (MSW) effect. Combining the recent experimental constraints on θ{sub 13} with predicted and observed supernova-produced abundance ratio {sup 11}B/{sup 7}Li encapsulated in the presolar grains from the Murchison meteorite, we show a marginal preference for an inverted neutrino mass hierarchy. We also discuss supernova relic neutrinos (SRN) that may indicate the softness of the equation of state (EoS) of nuclear matter and adiabatic conditions of the neutrino oscillation.
Self-accelerating universe in Galileon cosmology
International Nuclear Information System (INIS)
Silva, Fabio P.; Koyama, Kazuya
2009-01-01
We present a cosmological model with a solution that self-accelerates at late times without signs of ghost instabilities on small scales. The model is a natural extension of the Brans-Dicke (BD) theory including a nonlinear derivative interaction, which appears in a theory with the Galilean shift symmetry. The existence of the self-accelerating universe requires a negative BD parameter but, thanks to the nonlinear term, small fluctuations around the solution are stable on small scales. General relativity is recovered at early times and on small scales by this nonlinear interaction via the Vainshtein mechanism. At late time, gravity is strongly modified and the background cosmology shows a phantomlike behavior and the growth rate of structure formation is enhanced. Thus this model leaves distinct signatures in cosmological observations and it can be distinguished from standard LCDM cosmology.
Questions of Modern Cosmology Galileo's Legacy
D'Onofrio, Mauro
2009-01-01
Are we living in the "golden age" of cosmology? Are we close to understanding the nature of the unknown ingredients of the currently most accepted cosmological model and the physics of the early Universe? Or are we instead approaching a paradigm shift? What is dark matter and does it exist? How is it distributed around galaxies and clusters? Is the scientific community open to alternative ideas that may prompt a new scientific revolution - as the Copernican revolution did in Galileo's time? Do other types of supernovae exist that can be of interest for cosmology? Why have quasars never been effectively used as standard candles? Can you tell us about the scientific adventure of COBE? How does the extraction of the Cosmic Microwave Background anisotropy depend on the subtraction of the various astrophysical foregrounds? These, among many others, are the astrophysical, philosophical and sociological questions surrounding modern cosmology and the scientific community that Mauro D'Onofrio and Carlo Burigana pose t...
Julien Lesgourgues presents his book "Neutrino Cosmology"
2013-01-01
The role that neutrinos have played in the evolution of the Universe is the focus of one of the most fascinating research areas that has stemmed from the interplay between cosmology, astrophysics and particle physics. In this self-contained book, the authors bring together all aspects of the role of neutrinos in cosmology, spanning from leptogenesis to primordial nucleosynthesis and from their role in CMB and structure formation, to the problem of their direct detection. The book starts by guiding the reader through aspects of fundamental neutrino physics, such as the standard cosmological model and statistical mechanics in the expanding Universe, before discussing the history of neutrinos chronologically from the very early stages until today. "Neutrino Cosmology" by Julien Lesgourgues, Gianpiero Mangano, Gennaro Miele, Sergio Pastor, Cambridge University Press, 2013, ISBN 9781107013957. Monday 22 April 2013 at 4 p.m. in the Library, 52-1-052. Tea and coffee will be served...
Particles in astrophysics and cosmology: a dark connection
International Nuclear Information System (INIS)
Fornengo, Nicolao
2010-01-01
The particle physics interpretation of the missing-mass, or dark-matter, problem of cosmological and astrophysical nature is going to be posed under deep scrutiny in the next years. From the particle physics side, accelerators will deeply test theoretical ideas of new physics beyond the Standard Model, where particle candidates of dark matter are predicted. From the astrophysical side, many probes are already providing a great deal of independent information on the foreseen signals which can be produced by the galactic or extra-galactic dark matter. The ultimate hope is in fact the emergence of dark matter signals from the various sources of backgrounds and the rise of a coherent picture of new physics from the accelerator physics, astrophysics and cosmology sides. A very ambitious and far-reaching project, which will bring to a deeper level our understanding of the fundamental laws which rule the Universe.
Standard test method for wear testing with a pin-on-disk apparatus
American Society for Testing and Materials. Philadelphia
2005-01-01
1.1 This test method covers a laboratory procedure for determining the wear of materials during sliding using a pin-on-disk apparatus. Materials are tested in pairs under nominally non-abrasive conditions. The principal areas of experimental attention in using this type of apparatus to measure wear are described. The coefficient of friction may also be determined. 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
Standard test methods for elevated temperature tension tests of metallic materials
American Society for Testing and Materials. Philadelphia
2009-01-01
1.1 These test methods cover procedure and equipment for the determination of tensile strength, yield strength, elongation, and reduction of area of metallic materials at elevated temperatures. 1.2 Determination of modulus of elasticity and proportional limit are not included. 1.3 Tension tests under conditions of rapid heating or rapid strain rates are not included. 1.4 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
Aligning English grammar testing with European language standards
Directory of Open Access Journals (Sweden)
Bodrič Radmila
2015-01-01
Full Text Available In recent years, foreign language testing has gained in significance with the advent of The Common European Framework of Reference for Languages (2001 (CEFR, a European language document which set comparable standards for learning, teaching and assessing foreign languages. The CEFR was used to set the research aim of this paper - testing grammar at level B2. The main aim of the research was to determine grammatical competence at level B2 and additional aims included: (a determining which particular areas of grammar need to be learned by students at level B2, (b formulating grammatical descriptors for each individual area of grammar, (c determining the test’s threshold level which would fulfil the criteria for grammatical competence at level B2, and (d determining the extent to which students have mastered the given areas. The pre-testing was followed by the main testing on the sample of 164 students in two secondary schools. The results indicated that the quantity and quality of grammatical competence was lower than expected: 47% of the population failed to fulfil the basic level of grammatical competence. The causes may be attributed to the factors of a subjective and objective nature. Level B2 is demanding qualitatively as well as quantitatively, regarding both the formal and the functional complexity and scope of language use, which requires intensive language production, high levels of motivation and sound working habits in order to master the given grammatical structures.
Standard Test Method for Measuring Binocular Disparity in Transparent Parts
American Society for Testing and Materials. Philadelphia
2009-01-01
1.1 This test method covers the amount of binocular disparity that is induced by transparent parts such as aircraft windscreens, canopies, HUD combining glasses, visors, or goggles. This test method may be applied to parts of any size, shape, or thickness, individually or in combination, so as to determine the contribution of each transparent part to the overall binocular disparity present in the total “viewing system” being used by a human operator. 1.2 This test method represents one of several techniques that are available for measuring binocular disparity, but is the only technique that yields a quantitative figure of merit that can be related to operator visual performance. 1.3 This test method employs apparatus currently being used in the measurement of optical angular deviation under Method F 801. 1.4 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not con...
American Society for Testing and Materials. Philadelphia
2002-01-01
1.1 This test method covers the determination of the stability in storage, of liquid, water-base chemical cleaning compounds, used to clean the exterior surfaces of aircraft. 1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
Active galactic nuclei as cosmological probes.
Lusso, Elisabeta; Risaliti, Guido
2018-01-01
I will present the latest results on our analysis of the non-linear X-ray to UV relation in a sample of optically selected quasars from the Sloan Digital Sky Survey, cross-matched with the most recent XMM-Newton and Chandra catalogues. I will show that this correlation is not only very tight, but can be potentially even tighter by including a further dependence on the emission line full-width half maximum. This result imply that the non-linear X-ray to optical-ultraviolet luminosity relation is the manifestation of an ubiquitous physical mechanism, whose details are still unknown, that regulates the energy transfer from the accretion disc to the X-ray emitting corona in quasars. I will discuss what the perspectives of AGN in the context of observational cosmology are. I will introduce a novel technique to test the cosmological model using quasars as “standard candles” by employing the non-linear X-ray to UV relation as an absolute distance indicator.
Primordial nucleosynthesis: A cosmological point of view
International Nuclear Information System (INIS)
Mathews, G. J.; Kajino, T.; Yamazaki, D.; Kusakabe, M.; Cheoun, M.-K.
2014-01-01
Primordial nucleosynthesis remains as one of the pillars of modern cosmology. It is the test-ing ground upon which all cosmological models must ultimately rest. It is our only probe of the universe during the first few minutes of cosmic expansion and in particular during the important radiation-dominated epoch. These lectures review the basic equations of space-time, cosmology, and big bang nucleosynthesis. We will then review the current state of observational constraints on primordial abundances along with the key nuclear reactions and their uncertainties. We summarize which nuclear measure-ments are most crucial during the big bang. We also review various cosmological models and their constraints. In particular, we summarize the constraints that big bang nucleosynthesis places upon the possible time variation of fundamental constants, along with constraints on the nature and origin of dark matter and dark energy, long-lived supersymmetric particles, gravity waves, and the primordial magnetic field
Standard Test Method for Hydrophobic Surface Films by the Atomizer Test
American Society for Testing and Materials. Philadelphia
1965-01-01
1.1 This test method covers the detection of the presence of hydrophobic (nonwetting) films on surfaces and the presence of hydrophobic organic materials in processing ambients. When properly conducted, the test will enable detection of fractional molecular layers of hydrophobic organic contaminants. On very rough or porous surfaces the sensitivity of the test may be significantly decreased. 1.2 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
Standard Test Method for Hydrophobic Surface Films by the Water-Break Test
American Society for Testing and Materials. Philadelphia
2002-01-01
1.1 This test method covers the detection of the presence of hydrophobic (nonwetting) films on surfaces and the presence of hydrophobic organic materials in processing ambients. When properly conducted, the test will enable detection of molecular layers of hydrophobic organic contaminants. On very rough or porous surfaces, the sensitivity of the test may be significantly decreased. 1.2 The values stated in SI units are to be regarded as the standard. The inch-pound values given in parentheses are for information only. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
Standard test method for tension testing of structural alloys in liquid helium
American Society for Testing and Materials. Philadelphia
2009-01-01
1.1 This test method describes procedures for the tension testing of structural alloys in liquid helium. The format is similar to that of other ASTM tension test standards, but the contents include modifications for cryogenic testing which requires special apparatus, smaller specimens, and concern for serrated yielding, adiabatic heating, and strain-rate effects. 1.2 To conduct a tension test by this standard, the specimen in a cryostat is fully submerged in normal liquid helium (He I) and tested using crosshead displacement control at a nominal strain rate of 10−3 s−1 or less. Tests using force control or high strain rates are not considered. 1.3 This standard specifies methods for the measurement of yield strength, tensile strength, elongation, and reduction of area. The determination of the elastic modulus is treated in Test Method E 111. Note 1—The boiling point of normal liquid helium (He I) at sea level is 4.2 K (−269°C or −452.1°F or 7.6°R). It decreases with geographic elevation and is...
Is there evidence for additional neutrino species from cosmology?
Feeney, Stephen M.; Verde, Licia
2013-01-01
It has been suggested that recent cosmological and flavor-oscillation data favor the existence of additional neutrino species beyond the three predicted by the Standard Model of particle physics. We apply Bayesian model selection to determine whether there is indeed any evidence from current cosmological datasets for the standard cosmological model to be extended to include additional neutrino flavors. The datasets employed include cosmic microwave background temperature, polarization and lensing power spectra, and measurements of the baryon acoustic oscillation scale and the Hubble constant. We also consider other extensions to the standard neutrino model, such as massive neutrinos, and possible degeneracies with other cosmological parameters. The Bayesian evidence indicates that current cosmological data do not require any non-standard neutrino properties.
Standard test method for guided bend test for ductility of welds
American Society for Testing and Materials. Philadelphia
2002-01-01
1.1 This test method covers a guided bend test for the determination of soundness and ductility of welds in ferrous and nonferrous products. Defects, not shown by X rays, may appear in the surface of a specimen when it is subjected to progressive localized overstressing. This guided bend test has been developed primarily for plates and is not intended to be substituted for other methods of bend testing. 1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard. Note 1—For additional information see Terminology E 6, and American Welding Society Standard D 1.1. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
A curious explanation of some cosmological phenomena
International Nuclear Information System (INIS)
Vishwakarma, Ram Gopal
2013-01-01
Although observational cosmology has shown tremendous growth over the last decade, deep mysteries continue to haunt our theoretical understanding of the ingredients of the concordance cosmological model, which are mainly ‘dark’. More than 95% of the content of the energy–stress tensor has to be in the form of the inflaton field, dark matter and dark energy, which do not have any non-gravitational or laboratory evidence and remain unidentified. Moreover, the dark energy poses a serious confrontation between fundamental physics and cosmology. This makes a strong case to discover alternative theories that do not require the dark sectors of the standard approach to explain the observations. In the present situation, it would be important to gain insight about the requirements of the ‘would-be’ final theory from all possible means. In this context, this paper highlights some, hitherto unnoticed, interesting coincidences that may prove useful to develop insight about the ‘holy grail’ of gravitation. It appears that the requirement of the speculative dark sectors by the energy–stress tensor is indicative of a possible way out of the present crisis appearing in the standard cosmology, in terms of a theory wherein the energy–stress tensor does not play a direct role in the dynamics. It is shown that various cosmological observations can be explained satisfactorily in the framework of one such theory—the Milne model, without requiring the dark sectors of the standard approach. Moreover, the model evades the horizon, flatness and the cosmological constant problems afflicting the standard cosmology. Although Milne's theory is an incomplete, phenomenological theory, and cannot be the final theory of gravitation, nevertheless, it would be worthwhile to study these coincidences, which may help us develop insight about the would-be final theory. (paper)
A curious explanation of some cosmological phenomena
Gopal Vishwakarma, Ram
2013-05-01
Although observational cosmology has shown tremendous growth over the last decade, deep mysteries continue to haunt our theoretical understanding of the ingredients of the concordance cosmological model, which are mainly ‘dark’. More than 95% of the content of the energy-stress tensor has to be in the form of the inflaton field, dark matter and dark energy, which do not have any non-gravitational or laboratory evidence and remain unidentified. Moreover, the dark energy poses a serious confrontation between fundamental physics and cosmology. This makes a strong case to discover alternative theories that do not require the dark sectors of the standard approach to explain the observations. In the present situation, it would be important to gain insight about the requirements of the ‘would-be’ final theory from all possible means. In this context, this paper highlights some, hitherto unnoticed, interesting coincidences that may prove useful to develop insight about the ‘holy grail’ of gravitation. It appears that the requirement of the speculative dark sectors by the energy-stress tensor is indicative of a possible way out of the present crisis appearing in the standard cosmology, in terms of a theory wherein the energy-stress tensor does not play a direct role in the dynamics. It is shown that various cosmological observations can be explained satisfactorily in the framework of one such theory—the Milne model, without requiring the dark sectors of the standard approach. Moreover, the model evades the horizon, flatness and the cosmological constant problems afflicting the standard cosmology. Although Milne's theory is an incomplete, phenomenological theory, and cannot be the final theory of gravitation, nevertheless, it would be worthwhile to study these coincidences, which may help us develop insight about the would-be final theory.
Cosmological footprints of loop quantum gravity.
Grain, J; Barrau, A
2009-02-27
The primordial spectrum of cosmological tensor perturbations is considered as a possible probe of quantum gravity effects. Together with string theory, loop quantum gravity is one of the most promising frameworks to study quantum effects in the early universe. We show that the associated corrections should modify the potential seen by gravitational waves during the inflationary amplification. The resulting power spectrum should exhibit a characteristic tilt. This opens a new window for cosmological tests of quantum gravity.
Cosmological perturbations beyond linear order
CERN. Geneva
2013-01-01
Cosmological perturbation theory is the standard tool to understand the formation of the large scale structure in the Universe. However, its degree of applicability is limited by the growth of the amplitude of the matter perturbations with time. This problem can be tackled with by using N-body simulations or analytical techniques that go beyond the linear calculation. In my talk, I'll summarise some recent efforts in the latter that ameliorate the bad convergence of the standard perturbative expansion. The new techniques allow better analytical control on observables (as the matter power spectrum) over scales very relevant to understand the expansion history and formation of structure in the Universe.
Standard Test Methods for Wet Insulation Integrity Testing of Photovoltaic Modules
American Society for Testing and Materials. Philadelphia
2007-01-01
1.1 These test methods provide procedures to determine the insulation resistance of a photovoltaic (PV) module, i.e. the electrical resistance between the module's internal electrical components and its exposed, electrically conductive, non-current carrying parts and surfaces. 1.2 The insulation integrity procedures are a combination of wet insulation resistance and wet dielectric voltage withstand test procedures. 1.3 These procedures are similar to and reference the insulation integrity test procedures described in Test Methods E 1462, with the difference being that the photovoltaic module under test is immersed in a wetting solution during the procedures. 1.4 These test methods do not establish pass or fail levels. The determination of acceptable or unacceptable results is beyond the scope of these test methods. 1.5 The values stated in SI units are to be regarded as the standard. 1.6 There is no similar or equivalent ISO standard. 1.7 This standard does not purport to address all of the safety conce...
International Nuclear Information System (INIS)
Klebanov, I.; Susskind, L.
1988-10-01
We review Coleman's wormhole mechanism for the vanishing of the cosmological constant. We find a discouraging result that wormholes much bigger than the Planck size are generated. We also consider the implications of the wormhole theory for cosmology. 7 refs., 2 figs
Particle physics and cosmology
International Nuclear Information System (INIS)
Ellis, J.; Nanopoulos, D.
1983-01-01
The authors describe the connection between cosmology and particle physics in an introductory way. In this connection the big bang theory and unified gauge models of strong, electromagnetic, and weak interactions are considered. Furthermore cosmological nucleosynthesis is discussed in this framework, and the problem of cosmic neutrinos is considered with special regards to its rest mass. (HSI).
van de Weygaert, Rien; van Albada, Tjeerd S.
1996-01-01
A detailed account of the ways in which a square kilometer array could further cosmological research. Observational and theoretical studies of the large scale structure and morphology of the local universe are reviewed against the potential capabilities of a new generation telescope. Cosmological
Barkana, Rennan; Tsujikawa, Shinji; Kim, Jihn E; Nagamine, Kentaro
2018-01-01
The Encyclopedia of Cosmology, in four volumes, is a major, long-lasting, seminal reference at the graduate student level, laid out by the most prominent, respected researchers in the general field of Cosmology. These volumes will be a comprehensive review of the most important concepts and current status in the field, covering both theory and observation.
Astroparticle physics and cosmology
International Nuclear Information System (INIS)
Senjanovic, G.; Smirnov, A.Yu.; Thompson, G.
2001-01-01
In this volume a wide spectrum of topics of modern astroparticle physics, such as neutrino astrophysics, dark matter of the universe, high energy cosmic rays, topological defects in cosmology, γ-ray bursts, phase transitions at high temperatures, is covered. The articles written by top level experts in the field give a comprehensive view of the state-of-the-art of modern cosmology
Astroparticle physics and cosmology
Energy Technology Data Exchange (ETDEWEB)
Senjanovic, G; Smirnov, A Yu; Thompson, G [eds.
2001-11-15
In this volume a wide spectrum of topics of modern astroparticle physics, such as neutrino astrophysics, dark matter of the universe, high energy cosmic rays, topological defects in cosmology, {gamma}-ray bursts, phase transitions at high temperatures, is covered. The articles written by top level experts in the field give a comprehensive view of the state-of-the-art of modern cosmology.
Nuclear anapole moment and tests of the standard model
International Nuclear Information System (INIS)
Flambaum, V. V.
1999-01-01
There are two sources of parity nonconservation (PNC) in atoms: the electron-nucleus weak interaction and the magnetic interaction of electrons with the nuclear anapole moment. A nuclear anapole moment has recently been observed. This is the first discovery of an electromagnetic moment violating fundamental symmetries--the anapole moment violates parity and charge-conjugation invariance. We describe the anapole moment and how it can be produced. The anapole moment creates a circular magnetic field inside the nucleus. The interesting point is that measurements of the anapole allow one to study parity violation inside the nucleus through atomic experiments. We use the experimental result for the nuclear anapole moment of 133 Cs to find the strengths of the parity violating proton-nucleus and meson-nucleon forces. Measurements of the weak charge characterizing the strength of the electron-nucleon weak interaction provide tests of the Standard Model and a way of searching for new physics beyond the Standard Model. Atomic experiments give limits on the extra Z-boson, leptoquarks, composite fermions, and radiative corrections produced by particles that are predicted by new theories. The weak charge and nuclear anapole moment can be measured in the same experiment. The weak charge gives the mean value of the PNC effect while the anapole gives the difference of the PNC effects for the different hyperfine components of an electromagnetic transition. The interaction between atomic electrons and the nuclear anapole moment may be called the ''PNC hyperfine interaction.''
Testing the standard model of particle physics using lattice QCD
International Nuclear Information System (INIS)
Water, Ruth S van de
2007-01-01
Recent advances in both computers and algorithms now allow realistic calculations of Quantum Chromodynamics (QCD) interactions using the numerical technique of lattice QCD. The methods used in so-called '2+1 flavor' lattice calculations have been verified both by post-dictions of quantities that were already experimentally well-known and by predictions that occurred before the relevant experimental determinations were sufficiently precise. This suggests that the sources of systematic error in lattice calculations are under control, and that lattice QCD can now be reliably used to calculate those weak matrix elements that cannot be measured experimentally but are necessary to interpret the results of many high-energy physics experiments. These same calculations also allow stringent tests of the Standard Model of particle physics, and may therefore lead to the discovery of new physics in the future
Lesgourgues, Julien
2012-01-01
Neutrinos can play an important role in the evolution of the Universe, modifying some of the cosmological observables. In this contribution we summarize the main aspects of cosmological relic neutrinos and we describe how the precision of present cosmological data can be used to learn about neutrino properties, in particular their mass, providing complementary information to beta decay and neutrinoless double-beta decay experiments. We show how the analysis of current cosmological observations, such as the anisotropies of the cosmic microwave background or the distribution of large-scale structure, provides an upper bound on the sum of neutrino masses of order 1 eV or less, with very good perspectives from future cosmological measurements which are expected to be sensitive to neutrino masses well into the sub-eV range.
International Nuclear Information System (INIS)
Gekman, O.
1982-01-01
The brief essay of the development of the main ideas of relativistic cosmology is presented. The Einstein's cosmological work about the Universe - ''Cosmological considerations in connection with the general relativity theory'' - gave the basis to all further treatments in this field. In 1922 A. Friedman's work appeared, in which the first expanding Universe model was proposed as a solution of the Einstein field equations. The model was spherically closed, but its curvature radius was a function of time. About 1955 the searches for anisotropic homogeneous solutions to Einstein field equation began. It turned out that isotropic cosmological models are unstable in general. The predominant part of them transform to anisotropic at insignificant breaking of isotropy. The discovery of isotropic background cosmic radiation in 1965, along with the Hubble low of the Universe expansion, served as the direct confirmation of cosmology based on the Einstein theory
Cosmological constant--the weight of the vacuum
International Nuclear Information System (INIS)
Padmanabhan, T.
2003-01-01
Recent cosmological observations suggest the existence of a positive cosmological constant Λ with the magnitude Λ(Gℎ/c 3 )∼10 -123 . This review discusses several aspects of the cosmological constant both from the cosmological (Sections 1-6) and field theoretical (Sections 7-11) perspectives. After a brief introduction to the key issues related to cosmological constant and a historical overview, a summary of the kinematics and dynamics of the standard Friedmann model of the universe is provided. The observational evidence for cosmological constant, especially from the supernova results, and the constraints from the age of the universe, structure formation, Cosmic Microwave Background Radiation (CMBR) anisotropies and a few others are described in detail, followed by a discussion of the theoretical models (quintessence, tachyonic scalar field, ...) from different perspectives. The latter part of the review (Sections 7-11) concentrates on more conceptual and fundamental aspects of the cosmological constant like some alternative interpretations of the cosmological constant, relaxation mechanisms to reduce the cosmological constant to the currently observed value, the geometrical structure of the de Sitter spacetime, thermodynamics of the de Sitter universe and the role of string theory in the cosmological constant problem
A whirling plane of satellite galaxies around Centaurus A challenges cold dark matter cosmology.
Müller, Oliver; Pawlowski, Marcel S; Jerjen, Helmut; Lelli, Federico
2018-02-02
The Milky Way and Andromeda galaxies are each surrounded by a thin plane of satellite dwarf galaxies that may be corotating. Cosmological simulations predict that most satellite galaxy systems are close to isotropic with random motions, so those two well-studied systems are often interpreted as rare statistical outliers. We test this assumption using the kinematics of satellite galaxies around the Centaurus A galaxy. Our statistical analysis reveals evidence for corotation in a narrow plane: Of the 16 Centaurus A satellites with kinematic data, 14 follow a coherent velocity pattern aligned with the long axis of their spatial distribution. In standard cosmological simulations, cosmological paradigm. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.
Type Ia Supernova Intrinsic Magnitude Dispersion and the Fitting of Cosmological Parameters
Kim, A. G.
2011-02-01
I present an analysis for fitting cosmological parameters from a Hubble diagram of a standard candle with unknown intrinsic magnitude dispersion. The dispersion is determined from the data, simultaneously with the cosmological parameters. This contrasts with the strategies used to date. The advantages of the presented analysis are that it is done in a single fit (it is not iterative), it provides a statistically founded and unbiased estimate of the intrinsic dispersion, and its cosmological-parameter uncertainties account for the intrinsic-dispersion uncertainty. Applied to Type Ia supernovae, my strategy provides a statistical measure to test for subtypes and assess the significance of any magnitude corrections applied to the calibrated candle. Parameter bias and differences between likelihood distributions produced by the presented and currently used fitters are negligibly small for existing and projected supernova data sets.
Working on a Standard Joint Unit: A pilot test.
Casajuana, Cristina; López-Pelayo, Hugo; Mercedes Balcells, María; Miquel, Laia; Teixidó, Lídia; Colom, Joan; Gual, Antoni
2017-09-29
Assessing cannabis consumption remains complex due to no reliable registration systems. We tested the likelihood of establishing a Standard Joint Unit (SJU) which considers the main cannabinoids with implication on health through a naturalistic approach. Methodology. Pilot study with current cannabis users of four areas of Barcelona: universities, nightclubs, out-patient mental health service, and cannabis associations. We designed and administered a questionnaire on cannabis use-patterns and determined the willingness to donate a joint for analysis. Descriptive statistics were used to analyze the data. Forty volunteers answered the questionnaire (response rate 95%); most of them were men (72.5%) and young adults (median age 24.5 years; IQR 8.75 years) who consume daily or nearly daily (70%). Most participants consume marihuana (85%) and roll their joints with a median of 0.25 gr of marihuana. Two out of three (67.5%) stated they were willing to donate a joint. Obtaining an SJU with the planned methodology has proved to be feasible. Pre-testing resulted in an improvement of the questionnaire and retribution to incentivize donations. Establishing an SJU is essential to improve our knowledge on cannabis-related outcomes.
Pilot test of ANSI draft standard N13.29 environmental dosimetry -- Performance criteria for testing
International Nuclear Information System (INIS)
Klemic, G.; Shebell, P.; Monetti, M.; Raccah, F.; Sengupta, S.
1998-09-01
American National Standards Institute Draft N13.29 describes performance tests for environmental radiation dosimetry providers. If approved it would be the first step toward applying the types of performance testing now required in personnel dosimetry to environmental radiation monitoring. The objective of this study was to pilot test the draft standard, before it undergoes final balloting, on a small group of dosimetry providers that were selected to provide a mix of facility types, thermoluminescent dosimeter designs and monitoring program applications. The first phase of the pilot test involved exposing dosimeters to laboratory photon, beta, and x-ray sources at routine and accident dose levels. In the second phase, dosimeters were subjected to ninety days of simulated environmental conditions in an environmental chamber that cycled through extremes of temperature and humidity. Two out of seven participants passed all categories of the laboratory testing phase, and all seven passed the environmental test phase. While some relatively minor deficiencies were uncovered in the course of the pilot test, the results show that draft N13.29 describes useful tests that could be appropriate for environmental dosimetry providers. An appendix to this report contains recommendations that should be addressed by the N13.29 working group before draft N13.29 is submitted for balloting
COSMOLOGICAL ADAPTIVE MESH REFINEMENT MAGNETOHYDRODYNAMICS WITH ENZO
International Nuclear Information System (INIS)
Collins, David C.; Xu Hao; Norman, Michael L.; Li Hui; Li Shengtai
2010-01-01
In this work, we present EnzoMHD, the extension of the cosmological code Enzo to include the effects of magnetic fields through the ideal magnetohydrodynamics approximation. We use a higher order Godunov method for the computation of interface fluxes. We use two constrained transport methods to compute the electric field from those interface fluxes, which simultaneously advances the induction equation and maintains the divergence of the magnetic field. A second-order divergence-free reconstruction technique is used to interpolate the magnetic fields in the block-structured adaptive mesh refinement framework already extant in Enzo. This reconstruction also preserves the divergence of the magnetic field to machine precision. We use operator splitting to include gravity and cosmological expansion. We then present a series of cosmological and non-cosmological test problems to demonstrate the quality of solution resulting from this combination of solvers.
Planck 2015 results: XIII. Cosmological parameters
DEFF Research Database (Denmark)
Ade, P. A R; Aghanim, N.; Arnaud, M.
2016-01-01
is constrained to w =-1.006 ± 0.045, consistent with the expected value for a cosmological constant. The standard big bang nucleosynthesis predictions for the helium and deuterium abundances for the best-fit Planck base ΛCDM cosmology are in excellent agreement with observations. We also constraints...... of the theory; for example, combining Planck observations with other astrophysical data we find Neff = 3.15 ± 0.23 for the effective number of relativistic degrees of freedom, consistent with the value Neff = 3.046 of the Standard Model of particle physics. The sum of neutrino masses is constrained to â'mν
Cosmological N -body simulations including radiation perturbations
DEFF Research Database (Denmark)
Brandbyge, Jacob; Rampf, Cornelius; Tram, Thomas
2017-01-01
CosmologicalN-body simulations are the standard tools to study the emergence of the observed large-scale structure of the Universe. Such simulations usually solve for the gravitational dynamics of matter within the Newtonian approximation, thus discarding general relativistic effects such as the ......CosmologicalN-body simulations are the standard tools to study the emergence of the observed large-scale structure of the Universe. Such simulations usually solve for the gravitational dynamics of matter within the Newtonian approximation, thus discarding general relativistic effects...
Testing the Big Bang: Light elements, neutrinos, dark matter and large-scale structure
Schramm, David N.
1991-01-01
Several experimental and observational tests of the standard cosmological model are examined. In particular, a detailed discussion is presented regarding: (1) nucleosynthesis, the light element abundances, and neutrino counting; (2) the dark matter problems; and (3) the formation of galaxies and large-scale structure. Comments are made on the possible implications of the recent solar neutrino experimental results for cosmology. An appendix briefly discusses the 17 keV thing and the cosmological and astrophysical constraints on it.
How does pressure gravitate? Cosmological constant problem confronts observational cosmology
Narimani, Ali; Afshordi, Niayesh; Scott, Douglas
2014-08-01
An important and long-standing puzzle in the history of modern physics is the gross inconsistency between theoretical expectations and cosmological observations of the vacuum energy density, by at least 60 orders of magnitude, otherwise known as the cosmological constant problem. A characteristic feature of vacuum energy is that it has a pressure with the same amplitude, but opposite sign to its energy density, while all the precision tests of General Relativity are either in vacuum, or for media with negligible pressure. Therefore, one may wonder whether an anomalous coupling to pressure might be responsible for decoupling vacuum from gravity. We test this possibility in the context of the Gravitational Aether proposal, using current cosmological observations, which probe the gravity of relativistic pressure in the radiation era. Interestingly, we find that the best fit for anomalous pressure coupling is about half-way between General Relativity (GR), and Gravitational Aether (GA), if we include Planck together with WMAP and BICEP2 polarization cosmic microwave background (CMB) observations. Taken at face value, this data combination excludes both GR and GA at around the 3 σ level. However, including higher resolution CMB observations (``highL'') or baryonic acoustic oscillations (BAO) pushes the best fit closer to GR, excluding the Gravitational Aether solution to the cosmological constant problem at the 4- 5 σ level. This constraint effectively places a limit on the anomalous coupling to pressure in the parametrized post-Newtonian (PPN) expansion, ζ4 = 0.105 ± 0.049 (+highL CMB), or ζ4 = 0.066 ± 0.039 (+BAO). These represent the most precise measurement of this parameter to date, indicating a mild tension with GR (for ΛCDM including tensors, with 0ζ4=), and also among different data sets.
How does pressure gravitate? Cosmological constant problem confronts observational cosmology
International Nuclear Information System (INIS)
Narimani, Ali; Scott, Douglas; Afshordi, Niayesh
2014-01-01
An important and long-standing puzzle in the history of modern physics is the gross inconsistency between theoretical expectations and cosmological observations of the vacuum energy density, by at least 60 orders of magnitude, otherwise known as the cosmological constant problem. A characteristic feature of vacuum energy is that it has a pressure with the same amplitude, but opposite sign to its energy density, while all the precision tests of General Relativity are either in vacuum, or for media with negligible pressure. Therefore, one may wonder whether an anomalous coupling to pressure might be responsible for decoupling vacuum from gravity. We test this possibility in the context of the Gravitational Aether proposal, using current cosmological observations, which probe the gravity of relativistic pressure in the radiation era. Interestingly, we find that the best fit for anomalous pressure coupling is about half-way between General Relativity (GR), and Gravitational Aether (GA), if we include Planck together with WMAP and BICEP2 polarization cosmic microwave background (CMB) observations. Taken at face value, this data combination excludes both GR and GA at around the 3 σ level. However, including higher resolution CMB observations (''highL'') or baryonic acoustic oscillations (BAO) pushes the best fit closer to GR, excluding the Gravitational Aether solution to the cosmological constant problem at the 4- 5 σ level. This constraint effectively places a limit on the anomalous coupling to pressure in the parametrized post-Newtonian (PPN) expansion, ζ 4 = 0.105 ± 0.049 (+highL CMB), or ζ 4 = 0.066 ± 0.039 (+BAO). These represent the most precise measurement of this parameter to date, indicating a mild tension with GR (for ΛCDM including tensors, with 0ζ 4 =), and also among different data sets
Development of the Test Of Astronomy STandards (TOAST) Assessment Instrument
Slater, Timothy F.; Slater, S. J.
2008-05-01
Considerable effort in the astronomy education research (AER) community over the past several years has focused on developing assessment tools in the form of multiple-choice conceptual diagnostics and content knowledge surveys. This has been critically important in advancing the AER discipline so that researchers could establish the initial knowledge state of students as well as to attempt measure some of the impacts of innovative instructional interventions. Unfortunately, few of the existing instruments were constructed upon a solid list of clearly articulated and widely agreed upon learning objectives. This was not done in oversight, but rather as a result of the relative youth of AER as a discipline. Now that several important science education reform documents exist and are generally accepted by the AER community, we are in a position to develop, validate, and disseminate a new assessment instrument which is tightly aligned to the consensus learning goals stated by the American Astronomical Society - Chair's Conference on ASTRO 101, the American Association of the Advancement of Science's Project 2061 Benchmarks, and the National Research Council's National Science Education Standards. In response, researchers from the Cognition in Astronomy, Physics and Earth sciences Research (CAPER) Team at the University of Wyoming's Science & Math Teaching Center (UWYO SMTC) have designed a criterion-referenced assessment tool, called the Test Of Astronomy STandards (TOAST). Through iterative development, this instrument has a high degree of reliability and validity for instructors and researchers needing information on students’ initial knowledge state at the beginning of a course and can be used, in aggregate, to help measure the impact of course-length duration instructional strategies for courses with learning goals tightly aligned to the consensus goals of our community.
Quantum propagation across cosmological singularities
Gielen, Steffen; Turok, Neil
2017-05-01
The initial singularity is the most troubling feature of the standard cosmology, which quantum effects are hoped to resolve. In this paper, we study quantum cosmology with conformal (Weyl) invariant matter. We show that it is natural to extend the scale factor to negative values, allowing a large, collapsing universe to evolve across a quantum "bounce" into an expanding universe like ours. We compute the Feynman propagator for Friedmann-Robertson-Walker backgrounds exactly, identifying curious pathologies in the case of curved (open or closed) universes. We then include anisotropies, fixing the operator ordering of the quantum Hamiltonian by imposing covariance under field redefinitions and again finding exact solutions. We show how complex classical solutions allow one to circumvent the singularity while maintaining the validity of the semiclassical approximation. The simplest isotropic universes sit on a critical boundary, beyond which there is qualitatively different behavior, with potential for instability. Additional scalars improve the theory's stability. Finally, we study the semiclassical propagation of inhomogeneous perturbations about the flat, isotropic case, at linear and nonlinear order, showing that, at least at this level, there is no particle production across the bounce. These results form the basis for a promising new approach to quantum cosmology and the resolution of the big bang singularity.
Chen, Geoff C. -F; Suyu, Sherry H.; Wong, Kenneth C.; Fassnacht, Christopher D.; Chiueh, Tzihong; Halkola, Aleksi; Hu, I. Shing; Auger, Matthew W.; Koopmans, Léon V. E.; Lagattuta, David J.; McKean, John P.; Vegetti, Simona
2016-01-01
Accurate and precise measurements of the Hubble constant are critical for testing our current standard cosmological model and revealing possibly new physics. With Hubble Space Telescope (HST) imaging, each strong gravitational lens system with measured time delays can allow one to determine the
International Nuclear Information System (INIS)
Kehagias, A.; Riotto, A.
2016-01-01
Symmetries play an interesting role in cosmology. They are useful in characterizing the cosmological perturbations generated during inflation and lead to consistency relations involving the soft limit of the statistical correlators of large-scale structure dark matter and galaxies overdensities. On the other hand, in observational cosmology the carriers of the information about these large-scale statistical distributions are light rays traveling on null geodesics. Motivated by this simple consideration, we study the structure of null infinity and the associated BMS symmetry in a cosmological setting. For decelerating Friedmann-Robertson-Walker backgrounds, for which future null infinity exists, we find that the BMS transformations which leaves the asymptotic metric invariant to leading order. Contrary to the asymptotic flat case, the BMS transformations in cosmology generate Goldstone modes corresponding to scalar, vector and tensor degrees of freedom which may exist at null infinity and perturb the asymptotic data. Therefore, BMS transformations generate physically inequivalent vacua as they populate the universe at null infinity with these physical degrees of freedom. We also discuss the gravitational memory effect when cosmological expansion is taken into account. In this case, there are extra contribution to the gravitational memory due to the tail of the retarded Green functions which are supported not only on the light-cone, but also in its interior. The gravitational memory effect can be understood also from an asymptotic point of view as a transition among cosmological BMS-related vacua.
International Nuclear Information System (INIS)
Nojiri, S; Odintsov, S D; Oikonomou, V K
2016-01-01
We combine the unimodular gravity and mimetic gravity theories into a unified theoretical framework, which is proposed to provide a suggestive proposal for a framework that may assist in the discussion and search for a solution to the cosmological constant problem and the dark matter issue. After providing the formulation of the unimodular mimetic gravity and investigating all the new features that the vacuum unimodular gravity implies, by using the underlying reconstruction method, we realize some well known cosmological evolutions, with some of these being exotic for the ordinary Einstein–Hilbert gravity. Specifically we provide the vacuum unimodular mimetic gravity description of the de Sitter cosmology and of the perfect fluid with constant equation of state cosmology. As we demonstrate, these cosmologies can be realized by vacuum mimetic unimodular gravity, without the existence of any matter fluid source. Moreover, we investigate how cosmologically viable cosmologies, which are compatible with the recent observational data, can be realized by the vacuum unimodular mimetic gravity. Since in some cases, a graceful exit from inflation problem might exist, we provide a qualitative description of the mechanism that can potentially generate the graceful exit from inflation in these theories, by searching for the unstable de Sitter solutions in the context of unimodular mimetic theories of gravity. (paper)
Energy Technology Data Exchange (ETDEWEB)
Kehagias, A. [Physics Division, National Technical University of Athens, 15780 Zografou Campus, Athens (Greece); Riotto, A. [Department of Theoretical Physics,24 quai E. Ansermet, CH-1211 Geneva 4 (Switzerland); Center for Astroparticle Physics (CAP),24 quai E. Ansermet, CH-1211 Geneva 4 (Switzerland)
2016-05-25
Symmetries play an interesting role in cosmology. They are useful in characterizing the cosmological perturbations generated during inflation and lead to consistency relations involving the soft limit of the statistical correlators of large-scale structure dark matter and galaxies overdensities. On the other hand, in observational cosmology the carriers of the information about these large-scale statistical distributions are light rays traveling on null geodesics. Motivated by this simple consideration, we study the structure of null infinity and the associated BMS symmetry in a cosmological setting. For decelerating Friedmann-Robertson-Walker backgrounds, for which future null infinity exists, we find that the BMS transformations which leaves the asymptotic metric invariant to leading order. Contrary to the asymptotic flat case, the BMS transformations in cosmology generate Goldstone modes corresponding to scalar, vector and tensor degrees of freedom which may exist at null infinity and perturb the asymptotic data. Therefore, BMS transformations generate physically inequivalent vacua as they populate the universe at null infinity with these physical degrees of freedom. We also discuss the gravitational memory effect when cosmological expansion is taken into account. In this case, there are extra contribution to the gravitational memory due to the tail of the retarded Green functions which are supported not only on the light-cone, but also in its interior. The gravitational memory effect can be understood also from an asymptotic point of view as a transition among cosmological BMS-related vacua.
Cosmology and CPT violating neutrinos
Energy Technology Data Exchange (ETDEWEB)
Barenboim, Gabriela; Salvado, Jordi [Universitat de Valencia-CSIC, Departament de Fisica Teorica y Instituto de Fisica Corpuscular, Burjassot (Spain)
2017-11-15
The combination charge conjugation-parity-time reversal (CPT) is a fundamental symmetry in our current understanding of nature. As such, testing CPT violation is a strongly motivated path to explore new physics. In this paper we study CPT violation in the neutrino sector, giving for the first time a bound, for a fundamental particle, in the CPT violating particle-antiparticle gravitational mass difference. We argue that cosmology is nowadays the only data sensitive to CPT violation for the neutrino-antineutrino mass splitting and we use the latest data release from Planck combined with the current baryonic-acoustic-oscillation measurement to perform a full cosmological analysis. To show the potential of the future experiments we also show the results for Euclid, a next generation large scale structure experiment. (orig.)
Inflation after COBE: Lectures on inflationary cosmology
International Nuclear Information System (INIS)
Turner, M.S.
1992-01-01
In these lectures I review the standard hot big-bang cosmology, emphasizing its successes, its shortcomings, and its major challenge-a detailed understanding of the formation of structure in the Universe. I then discuss the motivations for and the fundamentals of inflationary cosmology, particularly emphasizing the quantum origin of metric (density and gravity-wave) perturbations. Inflation addresses the shortcomings of the standard cosmology and provides the ''initial data'' for structure formation. I conclude by addressing the implications of inflation for structure formation, evaluating the various cold dark matter models in the light of the recent detection of temperature anisotropies in the cosmic background radiation by COBE. In the near term, the study of structure formation offers a powerful probe of inflation, as well as specific inflationary models
Inflation after COBE: Lectures on inflationary cosmology
Energy Technology Data Exchange (ETDEWEB)
Turner, M.S. [Chicago Univ., IL (United States). Enrico Fermi Inst.]|[Fermi National Accelerator Lab., Batavia, IL (United States)
1992-12-31
In these lectures I review the standard hot big-bang cosmology, emphasizing its successes, its shortcomings, and its major challenge-a detailed understanding of the formation of structure in the Universe. I then discuss the motivations for and the fundamentals of inflationary cosmology, particularly emphasizing the quantum origin of metric (density and gravity-wave) perturbations. Inflation addresses the shortcomings of the standard cosmology and provides the ``initial data`` for structure formation. I conclude by addressing the implications of inflation for structure formation, evaluating the various cold dark matter models in the light of the recent detection of temperature anisotropies in the cosmic background radiation by COBE. In the near term, the study of structure formation offers a powerful probe of inflation, as well as specific inflationary models.
Cosmology and particle physics
International Nuclear Information System (INIS)
Barrow, J.D.
1982-01-01
A brief overview is given of recent work that integrates cosmology and particle physics. The observational data regarding the abundance of matter and radiation in the Universe is described. The manner in which the cosmological survival density of stable massive particles can be calculated is discussed along with the process of cosmological nucleosynthesis. Several applications of these general arguments are given with reference to the survival density of nucleons, neutrinos and unconfined fractionally charge particles. The use of nucleosynthesis to limit the number of lepton generations is described together with the implications of a small neutrino mass for the origin of galaxies and clusters. (Auth.)
Cosmology and particle physics
Energy Technology Data Exchange (ETDEWEB)
Steigman, G [California Univ., Santa Barbara (USA). Inst. for Theoretical Physics; Bartol Research Foundation, Newark, Delaware (USA))
1982-01-29
The cosmic connections between physics on the very largest and very smallest scales are reviewed with an emphasis on the symbiotic relation between elementary particle physics and cosmology. After a review of the early Universe as a cosmic accelerator, various cosmological and astrophysical constraints on models of particle physics are outlined. To illustrate this approach to particle physics via cosmology, reference is made to several areas of current research: baryon non-conservation and baryon asymmetry; free quarks, heavy hadrons and other exotic relics; primordial nucleosynthesis and neutrino masses.
Neutrino properties from cosmology
CERN. Geneva
2013-01-01
Future, massive large-scale structure survey have been presented and approved.On the theory side, a significant effort has bene devoted to achieve better modeling of small scale clustering that is of cosmological non-linearities. As a result it has become clear that forthcoming cosmological data have enough statitsical power to detect the effect of non-zero neutrino mass (even at the lower mass scale limit imposed by oscillations) and to constrain the absolute neutrino mass scale.Cosmological data can also constrain the numb...
Cosmological viability of the bimetric theory of gravitation
International Nuclear Information System (INIS)
Krygier, B.; Krempec-Krygier, J.
1983-01-01
The approximate solutions of field equations for flat radiative cosmological models in the second version of bimetric gravitation theory are discussed. They indicate that these cosmological models are ever expanding. The apparent magnitude-redshift relations for flat dust cosmological models for different theories of gravitation are described and compared. One can reject Dirac's additive creation theory and the first version of Rosen's bimetric theory on the basis of this observational test. (author)
Standardized Testing Program for Solid-State Hydrogen Storage Technologies
Energy Technology Data Exchange (ETDEWEB)
Miller, Michael A. [Southwest Research Institute; Page, Richard A. [Southwest Research Institute
2012-07-30
In the US and abroad, major research and development initiatives toward establishing a hydrogen-based transportation infrastructure have been undertaken, encompassing key technological challenges in hydrogen production and delivery, fuel cells, and hydrogen storage. However, the principal obstacle to the implementation of a safe, low-pressure hydrogen fueling system for fuel-cell powered vehicles remains storage under conditions of near-ambient temperature and moderate pressure. The choices for viable hydrogen storage systems at the present time are limited to compressed gas storage tanks, cryogenic liquid hydrogen storage tanks, chemical hydrogen storage, and hydrogen absorbed or adsorbed in a solid-state material (a.k.a. solid-state storage). Solid-state hydrogen storage may offer overriding benefits in terms of storage capacity, kinetics and, most importantly, safety.The fervor among the research community to develop novel storage materials had, in many instances, the unfortunate consequence of making erroneous, if not wild, claims on the reported storage capacities achievable in such materials, to the extent that the potential viability of emerging materials was difficult to assess. This problem led to a widespread need to establish a capability to accurately and independently assess the storage behavior of a wide array of different classes of solid-state storage materials, employing qualified methods, thus allowing development efforts to focus on those materials that showed the most promise. However, standard guidelines, dedicated facilities, or certification programs specifically aimed at testing and assessing the performance, safety, and life cycle of these emergent materials had not been established. To address the stated need, the Testing Laboratory for Solid-State Hydrogen Storage Technologies was commissioned as a national-level focal point for evaluating new materials emerging from the designated Materials Centers of Excellence (MCoE) according to
Cosmological helium production simplified
International Nuclear Information System (INIS)
Bernstein, J.; Brown, L.S.; Feinberg, G.
1988-01-01
We present a simplified model of helium synthesis in the early universe. The purpose of the model is to explain clearly the physical ideas relevant to the cosmological helium synthesis, in a manner that does not overlay these ideas with complex computer calculations. The model closely follows the standard calculation, except that it neglects the small effect of Fermi-Dirac statistics for the leptons. We also neglect the temperature difference between photons and neutrinos during the period in which neutrons and protons interconvert. These approximations allow us to express the neutron-proton conversion rates in a closed form, which agrees to 10% accuracy or better with the exact rates. Using these analytic expressions for the rates, we reduce the calculation of the neutron-proton ratio as a function of temperature to a simple numerical integral. We also estimate the effect of neutron decay on the helium abundance. Our result for this quantity agrees well with precise computer calculations. We use our semi-analytic formulas to determine how the predicted helium abundance varies with such parameters as the neutron life-time, the baryon to photon ratio, the number of neutrino species, and a possible electron-neutrino chemical potential. 19 refs., 1 fig., 1 tab
Constraining holographic cosmology using Planck data
Afshordi, Niayesh; Gould, Elizabeth; Skenderis, Kostas
2017-06-01
Holographic cosmology offers a novel framework for describing the very early Universe in which cosmological predictions are expressed in terms of the observables of a three-dimensional quantum field theory (QFT). This framework includes conventional slow-roll inflation, which is described in terms of a strongly coupled QFT, but it also allows for qualitatively new models for the very early Universe, where the dual QFT may be weakly coupled. The new models describe a universe which is nongeometric at early times. While standard slow-roll inflation leads to a (near-) power-law primordial power spectrum, perturbative super-renormalizable QFTs yield a new holographic spectral shape. Here, we compare the two predictions against cosmological observations. We use CosmoMC to determine the best fit parameters, and MultiNest for Bayesian evidence, comparing the likelihoods. We find that the dual QFT should be nonperturbative at the very low multipoles (l ≲30 ), while for higher multipoles (l ≳30 ) the new holographic model, based on perturbative QFT, fits the data just as well as the standard power-law spectrum assumed in Λ CDM cosmology. This finding opens the door to applications of nonperturbative QFT techniques, such as lattice simulations, to observational cosmology on gigaparsec scales and beyond.
Cosmological acceleration. Dark energy or modified gravity?
International Nuclear Information System (INIS)
Bludman, S.
2006-05-01
We review the evidence for recently accelerating cosmological expansion or ''dark energy'', either a negative pressure constituent in General Relativity (Dark Energy) or modified gravity (Dark Gravity), without any constituent Dark Energy. If constituent Dark Energy does not exist, so that our universe is now dominated by pressure-free matter, Einstein gravity must be modified at low curvature. The vacuum symmetry of any Robertson-Walker universe then characterizes Dark Gravity as low- or high-curvature modifications of Einstein gravity. The dynamics of either kind of ''dark energy'' cannot be derived from the homogeneous expansion history alone, but requires also observing the growth of inhomogeneities. Present and projected observations are all consistent with a small fine tuned cosmological constant, but also allow nearly static Dark Energy or gravity modified at cosmological scales. The growth of cosmological fluctuations will potentially distinguish between static and ''dynamic'' ''dark energy''. But, cosmologically distinguishing the Concordance Model ΛCDM from modified gravity will require a weak lensing shear survey more ambitious than any now projected. Dvali-Gabadadze-Porrati low-curvature modifications of Einstein gravity may also be detected in refined observations in the solar system (Lue and Starkman) or at the intermediate Vainstein scale (Iorio) in isolated galaxy clusters. Dark Energy's epicyclic character, failure to explain the original Cosmic Coincidence (''Why so small now?'') without fine tuning, inaccessibility to laboratory or solar system tests, along with braneworld theories, now motivate future precision solar system, Vainstein-scale and cosmological-scale studies of Dark Gravity. (Orig.)
Cosmological acceleration. Dark energy or modified gravity?
Energy Technology Data Exchange (ETDEWEB)
Bludman, S
2006-05-15
We review the evidence for recently accelerating cosmological expansion or ''dark energy'', either a negative pressure constituent in General Relativity (Dark Energy) or modified gravity (Dark Gravity), without any constituent Dark Energy. If constituent Dark Energy does not exist, so that our universe is now dominated by pressure-free matter, Einstein gravity must be modified at low curvature. The vacuum symmetry of any Robertson-Walker universe then characterizes Dark Gravity as low- or high-curvature modifications of Einstein gravity. The dynamics of either kind of ''dark energy'' cannot be derived from the homogeneous expansion history alone, but requires also observing the growth of inhomogeneities. Present and projected observations are all consistent with a small fine tuned cosmological constant, but also allow nearly static Dark Energy or gravity modified at cosmological scales. The growth of cosmological fluctuations will potentially distinguish between static and ''dynamic'' ''dark energy''. But, cosmologically distinguishing the Concordance Model {lambda}CDM from modified gravity will require a weak lensing shear survey more ambitious than any now projected. Dvali-Gabadadze-Porrati low-curvature modifications of Einstein gravity may also be detected in refined observations in the solar system (Lue and Starkman) or at the intermediate Vainstein scale (Iorio) in isolated galaxy clusters. Dark Energy's epicyclic character, failure to explain the original Cosmic Coincidence (''Why so small now?'') without fine tuning, inaccessibility to laboratory or solar system tests, along with braneworld theories, now motivate future precision solar system, Vainstein-scale and cosmological-scale studies of Dark Gravity. (Orig.)
Song, Jin-Zi; Wan, Min; Xu, Hui; Yao, Xiu-Jun; Zhang, Bo; Wang, Jin-Hong
2009-09-01
The major idea of this article is to discuss standardization and normalization for the product standard of medical devices. Analyze the problem related to the physical performance requirements and test methods during product standard drafting process and make corresponding suggestions.
The cosmological constant problem
International Nuclear Information System (INIS)
Dolgov, A.D.
1989-05-01
A review of the cosmological term problem is presented. Baby universe model and the compensating field model are discussed. The importance of more accurate data on the Hubble constant and the Universe age is stressed. 18 refs
Time in contemporary cosmology
International Nuclear Information System (INIS)
Mavrides, Stamatia
1980-01-01
Cosmological time is defined, as is coordinated universal time against local times of special relativity. The problems of time and matter, age of the universe, Goedel models, arrow of time, are also discussed [fr
International Nuclear Information System (INIS)
Coule, D H
2005-01-01
We contrast the initial condition requirements of various contemporary cosmological models including inflationary and bouncing cosmologies. Canonical quantization of general relativity is used, as a first approximation to full quantum gravity, to determine whether suitable initial conditions are present. Various proposals such as Hartle-Hawking's 'no boundary' or tunnelling boundary conditions are assessed on grounds of naturalness and fine tuning. Alternatively, a quiescent initial state or an initial closed timelike curve 'time machine' is considered. Possible extensions to brane models are also addressed. Further ideas about universe creation from a meta-universe are outlined. Semiclassical and time asymmetry requirements of cosmology are briefly discussed and contrasted with the black-hole final-state proposal. We compare the recent loop quantum cosmology of Bojowald and co-workers with these earlier schemes. A number of possible difficulties and limitations are outlined. (topical review)
International Nuclear Information System (INIS)
Senjanovic, G.; Virginia Polytechnic Inst. and State Univ., Blacksburg
1984-07-01
Extended supersymmetry, Kaluza-Klein theory and family unification all suggest the existence of mirror fermions, with same quantum numbers but opposite helicities from ordinary fermions. The laboratory and especially cosmological implications of such particles are reviewed and summarized. (author)
Lachieze-Rey, Marc
This book delivers a quantitative account of the science of cosmology, designed for a non-specialist audience. The basic principles are outlined using simple maths and physics, while still providing rigorous models of the Universe. It offers an ideal introduction to the key ideas in cosmology, without going into technical details. The approach used is based on the fundamental ideas of general relativity such as the spacetime interval, comoving coordinates, and spacetime curvature. It provides an up-to-date and thoughtful discussion of the big bang, and the crucial questions of structure and galaxy formation. Questions of method and philosophical approaches in cosmology are also briefly discussed. Advanced undergraduates in either physics or mathematics would benefit greatly from use either as a course text or as a supplementary guide to cosmology courses.
Ryden, Barbara
2017-01-01
This second edition of Introduction to Cosmology is an exciting update of an award-winning textbook. It is aimed primarily at advanced undergraduate students in physics and astronomy, but is also useful as a supplementary text at higher levels. It explains modern cosmological concepts, such as dark energy, in the context of the Big Bang theory. Its clear, lucid writing style, with a wealth of useful everyday analogies, makes it exceptionally engaging. Emphasis is placed on the links between theoretical concepts of cosmology and the observable properties of the universe, building deeper physical insights in the reader. The second edition includes recent observational results, fuller descriptions of special and general relativity, expanded discussions of dark energy, and a new chapter on baryonic matter that makes up stars and galaxies. It is an ideal textbook for the era of precision cosmology in the accelerating universe.
A Secure Test Technique for Pipelined Advanced Encryption Standard
Shi, Youhua; Togawa, Nozomu; Yanagisawa, Masao; Ohtsuki, Tatsuo
In this paper, we presented a Design-for-Secure-Test (DFST) technique for pipelined AES to guarantee both the security and the test quality during testing. Unlike previous works, the proposed method can keep all the secrets inside and provide high test quality and fault diagnosis ability as well. Furthermore, the proposed DFST technique can significantly reduce test application time, test data volume, and test generation effort as additional benefits.
Jegede, Olugbemiro J.; Okebukola, Peter Akinsola
1991-01-01
The supposition that observational skills can be influenced by students' belief in traditional African cosmology, beliefs, and superstitions was investigated. Students with a high level of belief in African traditional cosmology made fewer correct observations on the Traditional Cosmology Test (TCT) and the Test of Observational Skills (TOS) as…
Magnetohydrodynamics and Plasma Cosmology
Kleidis, Kostas; Kuiroukidis, Apostolos; Papadopoulos, Demetrios; Vlahos, Loukas
2007-09-01
We study the linear magnetohydrodynamic (MHD) equations, both in the Newtonian and the general-relativistic limit, as regards a viscous magnetized fluid of finite conductivity and discuss instability criteria. In addition, we explore the excitation of cosmological perturbations in anisotropic spacetimes, in the presence of an ambient magnetic field. Acoustic, electromagnetic (e/m) and fast-magnetosonic modes, propagating normal to the magnetic field, can be excited, resulting in several implications of cosmological significance.
International Nuclear Information System (INIS)
Novikov, I.D.
1999-01-01
In this talk a brief survey has been carried out on the development of cosmology from the days Leopold Infeld was active in the field up to the present. Attention in particular is paid to the history of our knowledge of Hubble's expansion, of the cosmological constant, of the average density of matter and its distribution, and of the related issue of possible types of matter in the Universe. (author)
Cosmological phase transitions
International Nuclear Information System (INIS)
Kolb, E.W.
1993-10-01
If modern ideas about the role of spontaneous symmetry breaking in fundamental physics are correct, then the Universe should have undergone a series of phase transitions early in its history. The study of cosmological phase transitions has become an important aspect of early-Universe cosmology. In this lecture I review some very recent work on three aspects of phase transitions: the electroweak transition, texture, and axions
Directory of Open Access Journals (Sweden)
Daywitt W. C.
2009-04-01
Full Text Available Both the big-bang and the quasi-steady-state cosmologies originate in some type of Planck state. This paper presents a new cosmological theory based on the Planck- vacuum negative-energy state, a state consisting of a degenerate collection of negative- energy Planck particles. A heuristic look at the Einstein field equation provides a con- vincing argument that such a vacuum state could provide a theoretical explanation for the visible universe.
Professional Testing Standards: What Educators Need To Know.
Camara, Wayne J.
Real and perceived misuses of educational tests, errors in test scoring and test use, and incidents of cheating on tests have been widely reported in local and national media. As educational tests take on additional importance for students, teachers, and schools, there is appropriate concern about the quality of assessments and the appropriate use…
Private Pilot Practical Test Standards for Airplane (SEL, MEL, SES, MES)
1995-05-01
The Private Pilot - Airplane Practical Test Standards book has been : published by the Federal Aviation Administration (FAA) to establish the : standards for the private pilot certification practical tests for the airplane : category and the single-e...
Standard Test Method for Oxyacetylene Ablation Testing of Thermal Insulation Materials
American Society for Testing and Materials. Philadelphia
2008-01-01
1.1 This test method covers the screening of ablative materials to determine the relative thermal insulation effectiveness when tested as a flat panel in an environment of a steady flow of hot gas provided by an oxyacetylene burner. 1.2 This test method should be used to measure and describe the properties of materials, products, or assemblies in response to heat and flame under controlled laboratory conditions and should not be used to describe or appraise the fire hazard of materials, products, or assemblies under actual fire conditions. However, results of this test method may be used as elements of a fire risk assessment which takes into account all of the factors which are pertinent to an assessment of the fire hazard of a particular end use. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limi...
Standard test method for measuring waste glass or glass ceramic durability by vapor hydration test
American Society for Testing and Materials. Philadelphia
2009-01-01
1.1 The vapor hydration test method can be used to study the corrosion of a waste forms such as glasses and glass ceramics upon exposure to water vapor at elevated temperatures. In addition, the alteration phases that form can be used as indicators of those phases that may form under repository conditions. These tests; which allow altering of glass at high surface area to solution volume ratio; provide useful information regarding the alteration phases that are formed, the disposition of radioactive and hazardous components, and the alteration kinetics under the specific test conditions. This information may be used in performance assessment (McGrail et al, 2002 (1) for example). 1.2 This test method must be performed in accordance with all quality assurance requirements for acceptance of the data. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practice...
Using standard serology blood tests to diagnose latent syphilis
Directory of Open Access Journals (Sweden)
G. L. Katunin
2016-01-01
Full Text Available Goal. To conduct a comparative assessment of the results of regulated serological tests obtained as a result of blood tests in patients suffering from latent syphilis. Materials and methods. The authors examined 187 patient medical records with newly diagnosed latent syphilis in FGBU GNTsDK (State Research Center for Dermatology, Venereology and Cosmetology, Health Ministry of the Russian Federation, in 2006-2015. The results of patient blood tests were analyzed with the use of non-treponemal (microprecipitation test/RPR and treponemal (passive hemagglutination test, immune-enzyme assay (IgA, IgM, IgG, IFabs, immunofluorescence test and Treponema pallidum immobilization test serology tests. Results. According to the results of blood tests of latent syphilis patients, the largest number of positive results was obtained as a result of treponemal serology tests such as immune-enzyme assay (100%, passive hemagglutination test (100% and IFabs (100%. The greatest number of negative results was observed in non-treponemal (microprecipitation test/RPR serology tests: in 136 (72.7% patients; evidently positive results (4+ test results were obtained in 8 (4.3% patients only. According to the results of a comparative analysis of blood tests in patients suffering from latent syphilis obtained with the use of treponemal serology tests, the greatest number of evidently positive results (4+ was noted for the passive hemagglutination test (67.9%. Negative treponemal test results were obtained with the use of the immunofluorescence test and Treponema pallidum immobilization test (21.9% and 11.8% of cases, respectively. Moreover, weakly positive results prevailed for the immunofluorescence test: in 65 (34.7% patients. Conclusion. These data confirm that the following treponemal tests belong to the most reliable ones for revealing patients suffering from latent syphilis: immune-enzyme assay, passive hemagglutination test and IFabs.
2010-08-11
... Hydrostatic Testing Provision of the Portable Fire Extinguishers Standard; Extension of the Office of... the information collection requirements contained in the Hydrostatic Testing provision of the Portable... 48729
No-scale supergravity and cosmology
International Nuclear Information System (INIS)
Deruelle, N.
1988-01-01
The confrontation of current unified theories with cosmoly may prove to be very fruteful. Indeed the demand that the cosmological models they induce match the standard scenario and be free of manifest pathologies imposes severe constraints on them. We thus show that no-scale supergravity (at least its simplest incarnation) may not provide acceptable models of the early universe [fr
Cosmology with cosmic microwave background anisotropy
Indian Academy of Sciences (India)
Measurements of CMB anisotropy and, more recently, polarization have played a very important role in allowing precise determination of various parameters of the `standard' cosmological model. The expectation of the paradigm of inflation and the generic prediction of the simplest realization of inflationary scenario in the ...
Roberts, Alex
2016-08-01
Recently, a new framework for describing the multiverse has been proposed which is based on the principles of quantum mechanics. The framework allows for well-defined predictions, both regarding global properties of the universe and outcomes of particular experiments, according to a single probability formula. This provides complete unification of the eternally inflating multiverse and many worlds in quantum mechanics. We elucidate how cosmological parameters can be calculated in this framework, and study the probability distribution for the value of the cosmological constant. We consider both positive and negative values, and find that the observed value is consistent with the calculated distribution at an order of magnitude level. In particular, in contrast to the case of earlier measure proposals, our framework prefers a positive cosmological constant over a negative one. These results depend only moderately on how we model galaxy formation and life evolution therein. We explore supersymmetric theories in which the Higgs mass is boosted by the non-decoupling D-terms of an extended U(1) X gauge symmetry, defined here to be a general linear combination of hypercharge, baryon number, and lepton number. Crucially, the gauge coupling, gX, is bounded from below to accommodate the Higgs mass, while the quarks and leptons are required by gauge invariance to carry non-zero charge under U(1)X. This induces an irreducible rate, sigmaBR, for pp → X → ll relevant to existing and future resonance searches, and gives rise to higher dimension operators that are stringently constrained by precision electroweak measurements. Combined, these bounds define a maximally allowed region in the space of observables, (sigmaBR, mX), outside of which is excluded by naturalness and experimental limits. If natural supersymmetry utilizes non-decoupling D-terms, then the associated X boson can only be observed within this window, providing a model independent 'litmus test' for this broad
USL/DBMS NASA/PC R and D project system testing standards
Dominick, Wayne D. (Editor); Kavi, Srinu; Moreau, Dennis R.; Yan, Lin
1984-01-01
A set of system testing standards to be used in the development of all C software within the NASA/PC Research and Development Project is established. Testing will be considered in two phases: the program testing phase and the system testing phase. The objective of these standards is to provide guidelines for the planning and conduct of program and software system testing.
2013-06-07
... the relevance, reliability, validity, and effectiveness of the FAA's aeronautical testing and training... Rulemaking Advisory Committee (ARAC) Airman Testing Standards and Training Working Group (ATSTWG) AGENCY... Certification Standards (ACS) documents developed by the Airman Testing Standards and Training WG for the...
Standardized methods for in-place filter testing
Energy Technology Data Exchange (ETDEWEB)
Dykes, M.; Fretthold, J.K.; Slawski, J.
1997-08-01
The conference minutes of a US DOE meeting held on in-place filter testing are presented. The purpose of the conference was to transfer technical in-place testing knowledge throughout the DOE complex. Major items discussed included purchase requisitions, in-place testing, instrumentation, and in-place test personnel qualifications and training. Future actions identified by conference attendees centered on establishing complex-wide DOE policies on training, inspection and testing, and filter specifications.
International Nuclear Information System (INIS)
1996-01-01
The volume contains 45 lectures which were given at the annual meeting of the German Society for Nondestructive Testing on May 13-15, 1996 at Lindau. The main subjects were: Standardization of nondestructive testing, irradiation testing, ultrasonic testing and electromagnetic processes. 13 individual articles were included in the ENERGY database. (MM) [de
International Nuclear Information System (INIS)
1996-01-01
The volume contains 49 poster articles which were presented at the Annual Meeting of the German Society for Nondestructive Testing at Lindau on May 13-15, 1996. The main subjects were: Standardization of nondestructive testing, irradiation testing, ultrasonic testing and electromagnetic processes. 16 individual articles were included in the ENERGY databank. (MM) [de
The Cosmological Constant Problem (1/2)
CERN. Geneva
2015-01-01
I will review the cosmological constant problem as a serious challenge to our notion of naturalness in Physics. Weinberg’s no go theorem is worked through in detail. I review a number of proposals possibly including Linde's universe multiplication, Coleman's wormholes, the fat graviton, and SLED, to name a few. Large distance modifications of gravity are also discussed, with causality considerations pointing towards a global modification as being the most sensible option. The global nature of the cosmological constant problem is also emphasized, and as a result, the sequestering scenario is reviewed in some detail, demonstrating the cancellation of the Standard Model vacuum energy through a global modification of General Relativity.
The Cosmological Constant Problem (2/2)
CERN. Geneva
2015-01-01
I will review the cosmological constant problem as a serious challenge to our notion of naturalness in Physics. Weinberg’s no go theorem is worked through in detail. I review a number of proposals possibly including Linde's universe multiplication, Coleman's wormholes, the fat graviton, and SLED, to name a few. Large distance modifications of gravity are also discussed, with causality considerations pointing towards a global modification as being the most sensible option. The global nature of the cosmological constant problem is also emphasized, and as a result, the sequestering scenario is reviewed in some detail, demonstrating the cancellation of the Standard Model vacuum energy through a global modification of General Relativity.
Cosmological implications of Higgs near-criticality.
Espinosa, J R
2018-03-06
The Standard Model electroweak (EW) vacuum, in the absence of new physics below the Planck scale, lies very close to the boundary between stability and metastability, with the last option being the most probable. Several cosmological implications of this so-called 'near-criticality' are discussed. In the metastable vacuum case, the main challenges that the survival of the EW vacuum faces during the evolution of the Universe are analysed. In the stable vacuum case, the possibility of implementing Higgs inflation is critically examined.This article is part of the Theo Murphy meeting issue 'Higgs cosmology'. © 2018 The Author(s).
Tests of the standard electroweak model in beta decay
Energy Technology Data Exchange (ETDEWEB)
Severijns, N.; Beck, M. [Universite Catholique de Louvain (UCL), Louvain-la-Neuve (Belgium); Naviliat-Cuncic, O. [Caen Univ., CNRS-ENSI, 14 (France). Lab. de Physique Corpusculaire
2006-05-15
We review the current status of precision measurements in allowed nuclear beta decay, including neutron decay, with emphasis on their potential to look for new physics beyond the standard electroweak model. The experimental results are interpreted in the framework of phenomenological model-independent descriptions of nuclear beta decay as well as in some specific extensions of the standard model. The values of the standard couplings and the constraints on the exotic couplings of the general beta decay Hamiltonian are updated. For the ratio between the axial and the vector couplings we obtain C{sub A},/C{sub V} = -1.26992(69) under the standard model assumptions. Particular attention is devoted to the discussion of the sensitivity and complementarity of different precision experiments in direct beta decay. The prospects and the impact of recent developments of precision tools and of high intensity low energy beams are also addressed. (author)
Tests of the standard electroweak model in beta decay
International Nuclear Information System (INIS)
Severijns, N.; Beck, M.; Naviliat-Cuncic, O.
2006-05-01
We review the current status of precision measurements in allowed nuclear beta decay, including neutron decay, with emphasis on their potential to look for new physics beyond the standard electroweak model. The experimental results are interpreted in the framework of phenomenological model-independent descriptions of nuclear beta decay as well as in some specific extensions of the standard model. The values of the standard couplings and the constraints on the exotic couplings of the general beta decay Hamiltonian are updated. For the ratio between the axial and the vector couplings we obtain C A ,/C V = -1.26992(69) under the standard model assumptions. Particular attention is devoted to the discussion of the sensitivity and complementarity of different precision experiments in direct beta decay. The prospects and the impact of recent developments of precision tools and of high intensity low energy beams are also addressed. (author)
The evolution of modern cosmology as seen through a personal walk across six decades
Narlikar, Jayant V.
2018-05-01
This highly personal account of evolution of cosmology spans a period of approximately six decades 1959-2017. It begins when in 1959 the author, as an undergraduate at Cambridge, was attracted to the subject by the thought provoking lectures by Fred Hoyle as well as by his popular books The Nature of Universe and The Frontiers of Astronomy. The result was that after a successful performance at the Mathematical Tripos (Part III) examination, he enrolled as a research student of Hoyle. In this article the author describes the interesting works in cosmology that kept him busy both in Cambridge and in India. The issues pertinent to cosmological research in the 1960s and 1970s included the Mach's principle, the Wheeler-Feynman theory relating the local electromagnetic arrow of time to the cosmological one, the observational tests of specific expanding universe models, and issues like singularity in quantum cosmology. However, post-1965, the nature of cosmological research changed dramatically with the discovery of the cosmic microwave background radiation (CMBR). Given the assumption that the CMBR is a relic of big bang there has been a host of papers on the early universe, going as close to the big bang as the very early universe would permit: around just 10-36 s. The author argues that despite the popularity of the standard hot big bang cosmology (SBBC) it rests on rather shaky foundations. On the theoretical side there is no well established physical framework to support the SBBC; nor is there independent observational support for its assumptions like the nonbaryonic dark matter, inflation and dark energy. While technological progress has made it possible to explore the universe in greater detail with open mind, today's cosmologists seem caught in a range of speculations in support of the big bang dogma. Thus, in modern times cosmology appears to have lost the Camelot spirit encouraging adventurous studies of the unknown. A spirit of openness is advocated to restore
The evolution of modern cosmology as seen through a personal walk across six decades
Narlikar, Jayant V.
2018-02-01
This highly personal account of evolution of cosmology spans a period of approximately six decades 1959-2017. It begins when in 1959 the author, as an undergraduate at Cambridge, was attracted to the subject by the thought provoking lectures by Fred Hoyle as well as by his popular books The Nature of Universe and The Frontiers of Astronomy. The result was that after a successful performance at the Mathematical Tripos (Part III) examination, he enrolled as a research student of Hoyle. In this article the author describes the interesting works in cosmology that kept him busy both in Cambridge and in India. The issues pertinent to cosmological research in the 1960s and 1970s included the Mach's principle, the Wheeler-Feynman theory relating the local electromagnetic arrow of time to the cosmological one, the observational tests of specific expanding universe models, and issues like singularity in quantum cosmology. However, post-1965, the nature of cosmological research changed dramatically with the discovery of the cosmic microwave background radiation (CMBR). Given the assumption that the CMBR is a relic of big bang there has been a host of papers on the early universe, going as close to the big bang as the very early universe would permit: around just 10-36 s. The author argues that despite the popularity of the standard hot big bang cosmology (SBBC) it rests on rather shaky foundations. On the theoretical side there is no well established physical framework to support the SBBC; nor is there independent observational support for its assumptions like the nonbaryonic dark matter, inflation and dark energy. While technological progress has made it possible to explore the universe in greater detail with open mind, today's cosmologists seem caught in a range of speculations in support of the big bang dogma. Thus, in modern times cosmology appears to have lost the Camelot spirit encouraging adventurous studies of the unknown. A spirit of openness is advocated to restore
Framework for a Comparative Accelerated Testing Standard for PV Modules: Preprint
Energy Technology Data Exchange (ETDEWEB)
Kurtz, S.; Wohlgemuth, J.; Yamamichi, M.; Sample, T.; Miller, D.; Meakin, D.; Monokroussos, C.; TamizhMani, M.; Kempe, M.; Jordan, D.; Bosco, N.; Hacke, P.; Bermudez, V.; Kondo, M.
2013-08-01
As the photovoltaic industry has grown, the interest in comparative accelerated testing has also grown. Private test labs offer testing services that apply greater stress than the standard qualification tests as tools for differentiating products and for gaining increased confidence in long-term PV investments. While the value of a single international standard for comparative accelerated testing is widely acknowledged, the development of a consensus is difficult. This paper strives to identify a technical basis for a comparative standard.
Cold dark matter in brane cosmology scenario
International Nuclear Information System (INIS)
Dahab, Eiman Abou El; Khalil, Shaaban
2006-01-01
We analyze the dark matter problem in the context of brane cosmology. We investigate the impact of the non-conventional brane cosmology on the relic abundance of non-relativistic stable particles in high and low reheating temperature scenarios. We show that in case of high reheating temperature, the brane cosmology may enhance the dark matter relic density by many order of magnitudes and a stringent lower bound on the five dimensional scale is obtained. We also consider low reheating temperature scenarios with chemical equilibrium and non-equilibrium. We emphasize that in non-equilibrium case, the resulting relic density is very small. While with equilibrium, it is increased by a factor of O(10 2 ) with respect to the standard thermal production. Therefore, dark matter particles with large cross section, which is favored by detection expirements, can be consistent with the recent relic density observational limits
Observational constraints on cosmological future singularities
Energy Technology Data Exchange (ETDEWEB)
Beltran Jimenez, Jose [Aix Marseille Univ, Universite de Toulon CNRS, CPT, Marseille (France); Lazkoz, Ruth [Euskal Herriko Unibertsitatea, Fisika Teorikoaren eta Zientziaren Historia Saila, Zientzia eta Teknologia Fakultatea, Bilbao (Spain); Saez-Gomez, Diego [Faculdade de Ciencias da Universidade de Lisboa, Departamento de Fisica, Instituto de Astrofisica e Ciencias do Espaco, Lisbon (Portugal); Salzano, Vincenzo [University of Szczecin, Institute of Physics, Szczecin (Poland)
2016-11-15
In this work we consider a family of cosmological models featuring future singularities. This type of cosmological evolution is typical of dark energy models with an equation of state violating some of the standard energy conditions (e.g. the null energy condition). Such a kind of behavior, widely studied in the literature, may arise in cosmologies with phantom fields, theories of modified gravity or models with interacting dark matter/dark energy. We briefly review the physical consequences of these cosmological evolution regarding geodesic completeness and the divergence of tidal forces in order to emphasize under which circumstances the singularities in some cosmological quantities correspond to actual singular spacetimes. We then introduce several phenomenological parameterizations of the Hubble expansion rate to model different singularities existing in the literature and use SN Ia, BAO and H(z) data to constrain how far in the future the singularity needs to be (under some reasonable assumptions on the behavior of the Hubble factor). We show that, for our family of parameterizations, the lower bound for the singularity time cannot be smaller than about 1.2 times the age of the universe, what roughly speaking means ∝2.8 Gyrs from the present time. (orig.)
Observational constraints on cosmological future singularities
International Nuclear Information System (INIS)
Beltran Jimenez, Jose; Lazkoz, Ruth; Saez-Gomez, Diego; Salzano, Vincenzo
2016-01-01
In this work we consider a family of cosmological models featuring future singularities. This type of cosmological evolution is typical of dark energy models with an equation of state violating some of the standard energy conditions (e.g. the null energy condition). Such a kind of behavior, widely studied in the literature, may arise in cosmologies with phantom fields, theories of modified gravity or models with interacting dark matter/dark energy. We briefly review the physical consequences of these cosmological evolution regarding geodesic completeness and the divergence of tidal forces in order to emphasize under which circumstances the singularities in some cosmological quantities correspond to actual singular spacetimes. We then introduce several phenomenological parameterizations of the Hubble expansion rate to model different singularities existing in the literature and use SN Ia, BAO and H(z) data to constrain how far in the future the singularity needs to be (under some reasonable assumptions on the behavior of the Hubble factor). We show that, for our family of parameterizations, the lower bound for the singularity time cannot be smaller than about 1.2 times the age of the universe, what roughly speaking means ∝2.8 Gyrs from the present time. (orig.)
American Society for Testing and Materials. Philadelphia
2010-01-01
1.1 This is a quantitative test method applicable to determining the mass percent of uranium isotopes in uranium hexafluoride (UF6) samples with 235U concentrations between 0.1 and 5.0 mass %. 1.2 This test method may be applicable for the entire range of 235U concentrations for which adequate standards are available. 1.3 This test method is for analysis by a gas magnetic sector mass spectrometer with a single collector using interpolation to determine the isotopic concentration of an unknown sample between two characterized UF6 standards. 1.4 This test method is to replace the existing test method currently published in Test Methods C761 and is used in the nuclear fuel cycle for UF6 isotopic analyses. 1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appro...
Remark on application of the Banach metric method to cosmology
International Nuclear Information System (INIS)
Szydlowski, M.; Heller, M.
1982-01-01
If the cosmological equations can be reduced to the form of a dynamic system, the space of all their solutions is a Banach space. The influence of different parameters on the dynamics of the world models can be easily studied by means of the Banach metric. The method is tested for the Friedman cosmological models perturbed by the bulk viscosity. (author)
Multiple images of our galaxy in closed, multiply connected cosmologies
International Nuclear Information System (INIS)
Fagundes, H.V.
1985-01-01
Friedmanian cosmology with multiply connected spatial sections allows multiple images of cosmic sources, in particular of the galaxy itself. This is illustrated with a specific example of a closed hyperbolic model and a brief mention of a spherical model. Such images may eventually become observable (or recognized as such), thus providing a new test of relativistic cosmology. (Author) [pt
Practical issues for testing thin film PV modules at standard test conditions.
Marín González, Omar; Raga Arroyo, Manuela Pilar; Alonso Garcia, M. Carmen; Muñoz-García, Miguel Angel
2013-01-01
Thin film photovoltaic (TF) modules have gained importance in the photovoltaic (PV) market. New PV plants increasingly use TF technologies. In order to have a reliable sample of a PV module population, a huge number of modules must be measured. There is a big variety of materials used in TF technology. Some of these modules are made of amorphous or microcrystalline silicon. Other are made of CIS or CdTe. Not all these materials respond the same under standard test conditions (STC) of power...
Cognitive Fatigue Influences Students’ Performance on Standardized Tests
DEFF Research Database (Denmark)
Sievertsen, Hans Henrik; Gino, Francesca; Piovesan, Marco
2016-01-01
/10 and 2012/13, we find that, for every hour later in the day, test scores decrease by 0.9% of an SD. In addition, a 20- to 30-minute break improves average test scores. Time of day affects students’ test performance because, over the course of a regular day, students’ mental resources get taxed. Thus...
On the cosmological gravitational waves and cosmological distances
Belinski, V. A.; Vereshchagin, G. V.
2018-03-01
We show that solitonic cosmological gravitational waves propagated through the Friedmann universe and generated by the inhomogeneities of the gravitational field near the Big Bang can be responsible for increase of cosmological distances.
Testing non-standard CP violation in neutrino propagation
International Nuclear Information System (INIS)
Winter, Walter
2009-01-01
Non-standard physics which can be described by effective four fermion interactions may be an additional source of CP violation in the neutrino propagation. We discuss the detectability of such a CP violation at a neutrino factory. We assume the current baseline setup of the international design study of a neutrino factory (IDS-NF) for the simulation. We find that the CP violation from certain non-standard interactions is, in principle, detectable significantly below their current bounds - even if there is no CP violation in the standard oscillation framework. Therefore, a new physics effect might be mis-interpreted as the canonical Dirac CP violation, and a possibly even more exciting effect might be missed
The Nature of the Cosmological Constant Problem
Maia, M. D.; Capistrano, A. J. S.; Monte, E. M.
General relativity postulates the Minkowski space-time as the standard (flat) geometry against which we compare all curved space-times and also as the gravitational ground state where particles, quantum fields and their vacua are defined. On the other hand, experimental evidences tell that there exists a non-zero cosmological constant, which implies in a deSitter ground state, which not compatible with the assumed Minkowski structure. Such inconsistency is an evidence of the missing standard of curvature in Riemann's geometry, which in general relativity manifests itself in the form of the cosmological constant problem. We show how the lack of a curvature standard in Riemann's geometry can be fixed by Nash's theorem on metric perturbations. The resulting higher dimensional gravitational theory is more general than general relativity, similar to brane-world gravity, but where the propagation of the gravitational field along the extra dimensions is a mathematical necessity, rather than a postulate. After a brief introduction to Nash's theorem, we show that the vacuum energy density must remain confined to four-dimensional space-times, but the cosmological constant resulting from the contracted Bianchi identity represents a gravitational term which is not confined. In this case, the comparison between the vacuum energy and the cosmological constant in general relativity does not make sense. Instead, the geometrical fix provided by Nash's theorem suggests that the vacuum energy density contributes to the perturbations of the gravitational field.
International Nuclear Information System (INIS)
Schramm, D.N.; Fields, B.; Thomas, D.
1992-01-01
The possible implications of the quark-hadron transition for cosmology are explored. Possible surviving signatures are discussed. In particular, the possibility of generating a dark matter candidate such as strange nuggets or planetary mass black holes is noted. Much discussion is devoted to the possible role of the transition for cosmological nucleosynthesis. It is emphasized that even an optimized first order phase transition will not significantly alter the nucleosynthesis constraints on the cosmological baryon density nor on neutrino counting. However, it is noted that Be and B observations in old stars may eventually be able to be a signature of a cosmologically significant quark-hadron transition. It is pointed out that the critical point in this regard is whether the observed B/Be ratio can be produced by spallation processes or requires cosmological input. Spallation cannot produce a B/Be ratio below 7.6. A supporting signature would be Be and B ratios to oxygen that greatly exceed galactic values. At present, all data is still consistent with a spallagenic origin
Inhomogeneous anisotropic cosmology
International Nuclear Information System (INIS)
Kleban, Matthew; Senatore, Leonardo
2016-01-01
In homogeneous and isotropic Friedmann-Robertson-Walker cosmology, the topology of the universe determines its ultimate fate. If the Weak Energy Condition is satisfied, open and flat universes must expand forever, while closed cosmologies can recollapse to a Big Crunch. A similar statement holds for homogeneous but anisotropic (Bianchi) universes. Here, we prove that arbitrarily inhomogeneous and anisotropic cosmologies with “flat” (including toroidal) and “open” (including compact hyperbolic) spatial topology that are initially expanding must continue to expand forever at least in some region at a rate bounded from below by a positive number, despite the presence of arbitrarily large density fluctuations and/or the formation of black holes. Because the set of 3-manifold topologies is countable, a single integer determines the ultimate fate of the universe, and, in a specific sense, most 3-manifolds are “flat” or “open”. Our result has important implications for inflation: if there is a positive cosmological constant (or suitable inflationary potential) and initial conditions for the inflaton, cosmologies with “flat” or “open” topology must expand forever in some region at least as fast as de Sitter space, and are therefore very likely to begin inflationary expansion eventually, regardless of the scale of the inflationary energy or the spectrum and amplitude of initial inhomogeneities and gravitational waves. Our result is also significant for numerical general relativity, which often makes use of periodic (toroidal) boundary conditions.
Is cosmic acceleration proven by local cosmological probes?
Tutusaus, I.; Lamine, B.; Dupays, A.; Blanchard, A.
2017-06-01
Context. The cosmological concordance model (ΛCDM) matches the cosmological observations exceedingly well. This model has become the standard cosmological model with the evidence for an accelerated expansion provided by the type Ia supernovae (SNIa) Hubble diagram. However, the robustness of this evidence has been addressed recently with somewhat diverging conclusions. Aims: The purpose of this paper is to assess the robustness of the conclusion that the Universe is indeed accelerating if we rely only on low-redshift (z ≲ 2) observations, that is to say with SNIa, baryonic acoustic oscillations, measurements of the Hubble parameter at different redshifts, and measurements of the growth of matter perturbations. Methods: We used the standard statistical procedure of minimizing the χ2 function for the different probes to quantify the goodness of fit of a model for both ΛCDM and a simple nonaccelerated low-redshift power law model. In this analysis, we do not assume that supernovae intrinsic luminosity is independent of the redshift, which has been a fundamental assumption in most previous studies that cannot be tested. Results: We have found that, when SNIa intrinsic luminosity is not assumed to be redshift independent, a nonaccelerated low-redshift power law model is able to fit the low-redshift background data as well as, or even slightly better, than ΛCDM. When measurements of the growth of structures are added, a nonaccelerated low-redshift power law model still provides an excellent fit to the data for all the luminosity evolution models considered. Conclusions: Without the standard assumption that supernovae intrinsic luminosity is independent of the redshift, low-redshift probes are consistent with a nonaccelerated universe.
49 CFR 219.701 - Standards for drug and alcohol testing.
2010-10-01
... 49 Transportation 4 2010-10-01 2010-10-01 false Standards for drug and alcohol testing. 219.701... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION CONTROL OF ALCOHOL AND DRUG USE Drug and Alcohol Testing Procedures § 219.701 Standards for drug and alcohol testing. (a) Drug testing required or authorized by subparts B...
Preliminary Evaluation of a New Cosmology Curriculum
Coble, Kimberly A.; Martin, Dominique; Hayes, Patrycia; Targett, Tom; Bailey, Janelle M.; Cominsky, Lynn R.
2015-01-01
Informed by our research on student understanding of cosmology, The Big Ideas in Cosmology is an immersive set of web-based learning modules that integrates text, figures, and visualizations with short and long interactive tasks and real cosmological data. This enables the transformation of general education astronomy and cosmology classes from primarily lecture and book-based courses to a more engaging format that builds important STEM skills.During the spring 2014 semester, we field-tested a subset of chapters with the general education astronomy and cosmology classes at Sonoma State University in a flipped-classroom format. We administered pre and post content and attitude assessments in the two flipped classes as well as two lecture classes. The majority of cosmology students had taken astronomy before whereas the astronomy students had not.When switching to an active mode of learning (e.g., flipped classroom instead of lecture), many instructors report pushback from students. We saw this effect from students in course evaluations, who reported dissatisfaction with "having to do more work." However, the students in the flipped section in astronomy made greater gains on the multiple choice content assessment than the students in either of the two lecture sections. On the attitude assessment (the CLASS), the cosmology students made a small shift toward more expert-like opinions. Preliminary results from open-ended content surveys indicate that, prior to instruction, students had difficulty answering 'why' or 'how do we know' questions; that post-instruction, students are less likely to respond "I don't know" or to leave an answer blank; and that students using the modules made gains in their content knowledge.Module development was supported by NASA ROSES E/PO Grant #NNXl0AC89G, the Illinois Space Grant Consortium, the Fermi E/PO program, Sonoma State University's Space Science Education and Public Outreach Group, and Great River Technology
42 CFR 493.1423 - Standard; Testing personnel qualifications.
2010-10-01
..., or bachelor's degree in a chemical, physical, biological or clinical laboratory science, or medical... stability and storage; (F) The skills required to implement the quality control policies and procedures of... HUMAN SERVICES (CONTINUED) STANDARDS AND CERTIFICATION LABORATORY REQUIREMENTS Personnel for Nonwaived...
Multicultural Standardization and Validation of TEMAS, a Thematic Apperception Test.
Costantino, Giuseppe; Malgady, Robert G.
Mental health clinical services research has emphasized the urgency of developing new psychometric instruments for non-biased psychological assessment of minority and non-minority children of diverse cultural groups in the United States. Background multicultural standardization and validation information is presented for Tell-Me-A-Story (TEMAS)--a…