1,104 research outputs found
Gravitational waves in an anomaly-induced inflation
The behaviour of gravitational waves in the anomaly-induced inflationary
phase is studied. The metric perturbations exhibit a stable behaviour, with a
very moderate growth in the amplitude of the waves. The spectral indice is
computed, revealing an almost flat spectrum.Comment: 4 pages. Talk presented at IRGA 2003 (Renormalization Group and
Anomalies in Gravitation and Cosmology, Ouro Preto, Brazil, 16-23 March,
2003
2021 presidential address a year to remember: an extraordinary journey onto a promising path of inclusion and agility
As I preparedmy presidential address, what came to mind wasMischel's (1977: 346) work on situational strength, when he asked: "When are situations most likely to exert powerful effects and, conversely,when are person variables likely to bemost influential?" Situations matter most when they are strong, as they constrain options and provide clear signals about expectations. My presidential year provided a strong situation in the form of COVID-19 and the surging visibility of racial inequality in society. Both of thesewere united in their focus on the absence of health-the loss of life from COVID-19 or from racist brutality
Raised cortisol excretion rate in urine and contamination by topical steroids
No abstract available
On the stability of the anomaly-induced inflation
We analyze various phases of inflation based on the anomaly-induced effective
action of gravity (modified Starobinsky model), taking the cosmological
constant Lambda and k=0, +/- 1 topologies into account. The total number of the
inflationary e-folds may be enormous, but at the last 65 of them the inflation
greatly slows down due to the contributions of the massive particles. For the
supersymmetric particle content, the stability of inflation holds from the
initial point at the sub-Planck scale until the supersymmetry breaks down.
After that the universe enters into the unstable regime with the eventual
transition into the stable FRW-like evolution with small positive cosmological
constant. It is remarkable, that all this follows automatically, without
fine-tuning of any sort, independent on the values of Lambda and k. Finally, we
consider the stability under the metric perturbations during the last 65
e-folds of inflation and find that the amplitude of the ones with the
wavenumber below a certain cutoff has an acceptable range.Comment: 27 pages, LaTeX, 8 figures, some misprints correcte
Goodness-of-fit tests of Gaussianity: constraints on the cumulants of the MAXIMA data
In this work, goodness-of-fit tests are adapted and applied to CMB maps to
detect possible non-Gaussianity. We use Shapiro-Francia test and two Smooth
goodness-of-fit tests: one developed by Rayner and Best and another one
developed by Thomas and Pierce. The Smooth tests test small and smooth
deviations of a prefixed probability function (in our case this is the
univariate Gaussian). Also, the Rayner and Best test informs us of the kind of
non-Gaussianity we have: excess of skewness, of kurtosis, and so on. These
tests are optimal when the data are independent. We simulate and analyse
non-Gaussian signals in order to study the power of these tests. These
non-Gaussian simulations are constructed using the Edgeworth expansion, and
assuming pixel-to-pixel independence. As an application, we test the
Gaussianity of the MAXIMA data. Results indicate that the MAXIMA data are
compatible with Gaussianity. Finally, the values of the skewness and kurtosis
of MAXIMA data are constrained by |S| \le 0.035 and |K| \le 0.036 at the 99%
confidence level.Comment: New Astronomy Reviews, in pres
Divided Differences & Restriction Operator on Paley-Wiener Spaces for Carleson Sequences
For a sequence of complex numbers we consider the restriction
operator defined on Paley-Wiener spaces
(). Lyubarskii and Seip gave necessary and sufficient conditions on
for to be an isomorphism between and a
certain weighted space. The Carleson condition appears to be necessary.
We extend their result to Carleson sequences (finite unions of disjoint
Carleson sequences). More precisely, we give necessary and sufficient
conditions for to be an isomorphism between and
an appropriate sequence space involving divided differences
Goodness-of-Fit Tests to study the Gaussianity of the MAXIMA data
Goodness-of-Fit tests, including Smooth ones, are introduced and applied to
detect non-Gaussianity in Cosmic Microwave Background simulations. We study the
power of three different tests: the Shapiro-Francia test (1972), the
uncategorised smooth test developed by Rayner and Best(1990) and the Neyman's
Smooth Goodness-of-fit test for composite hypotheses (Thomas and Pierce 1979).
The Smooth Goodness-of-Fit tests are designed to be sensitive to the presence
of ``smooth'' deviations from a given distribution. We study the power of these
tests based on the discrimination between Gaussian and non-Gaussian
simulations. Non-Gaussian cases are simulated using the Edgeworth expansion and
assuming pixel-to-pixel independence. Results show these tests behave similarly
and are more powerful than tests directly based on cumulants of order 3, 4, 5
and 6. We have applied these tests to the released MAXIMA data. The applied
tests are built to be powerful against detecting deviations from univariate
Gaussianity. The Cholesky matrix corresponding to signal (based on an assumed
cosmological model) plus noise is used to decorrelate the observations previous
to the analysis. Results indicate that the MAXIMA data are compatible with
Gaussianity.Comment: MNRAS, in pres
Unraveling disruptions: how employees pick up signals of change
Psychological contracts reside in the eye of the beholder and capture the employee-employer exchange relationship. It is a dynamic relationship as employees deliberately manage and change their psychological contract over time. Triggers seem to be the drivers underpinning this dynamism. Yet little is known about how these triggers operate and affect the psychological contract. To address this, we explore triggers and their impact using a 6-week daily diary study (N = 117). We found a linear chain of positive relationships from initial triggers to connectedness of past triggers, to the experience of negative emotions, to the expected reoccurrence of the initial trigger, ultimately disrupting the psychological contract. The findings revealed the dynamic effect of triggers on the employment relationship, not only by exposing the underlying micro-processes, but also by revealing that the impact of triggers can linger for approximately 11 days before leveling off. These findings suggest that the psychological contract may fluctuate on a daily basis due to the influence of triggers. The theoretical implications for understanding the dynamic nature of the psychological contract are discussed in relation to the disruptive role of triggers
Non-Newtonian effects in the peristaltic flow of a Maxwell fluid
We analyzed the effect of viscoelasticity on the dynamics of fluids in porous
media by studying the flow of a Maxwell fluid in a circular tube, in which the
flow is induced by a wave traveling on the tube wall. The present study
investigates novelties brought about into the classic peristaltic mechanism by
inclusion of non-Newtonian effects that are important, for example, for
hydrocarbons. This problem has numerous applications in various branches of
science, including stimulation of fluid flow in porous media under the effect
of elastic waves. We have found that in the extreme non-Newtonian regime there
is a possibility of a fluid flow in the direction {\it opposite} to the
propagation of the wave traveling on the tube wall.Comment: to Appear in Phys. Rev. E., 01 September 2001 issu
Hoop conjecture for colliding black holes : non-time-symmetric initial data
The hoop conjecture is well confirmed in momentarily static spaces, but it
has not been investigated systematically for the system with relativistic
motion. To confirm the hoop conjecture for non-time-symmetric initial data, we
consider the initial data of two colliding black holes with momentum and search
an apparent horizon that encloses two black holes. In testing the hoop
conjecture, we use two definitions of gravitational mass : one is the ADM mass
and the other is the quasi-local mass defined by Hawking. Although both
definitions of gravitational mass give fairly consistent picture of the hoop
conjecture, the hoop conjecture with the Hawking mass can judge the existence
of an apparent horizon for wider range of parameters of the initial data
compared to the ADM mass.Comment: 15pages, 4 figure
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