549 research outputs found
Limits on Supersymmetric Dark Matter From EGRET Observations of the Galactic Center Region
In most supersymmetic models, neutralino dark matter particles are predicted
to accumulate in the Galactic center and annihilate generating, among other
products, gamma rays. The EGRET experiment has made observations in this
region, and is sensitive to gamma rays from 30 MeV to 30 GeV. We have
used an improved point source analysis including an energy dependent point
spread function and an unbinned maximum likelihood technique, which has allowed
us to significantly lower the limits on gamma ray flux from the Galactic
center. We find that the present EGRET data can limit many supersymmetric
models if the density of the Galactic dark matter halo is cuspy or spiked
toward the Galactic center. We also discuss the ability of GLAST to test these
models.Comment: 4 pages, 3 figure
Estimate of the Cosmological Bispectrum from the MAXIMA-1 Cosmic Microwave Background Map
We use the measurement of the cosmic microwave background taken during the
MAXIMA-1 flight to estimate the bispectrum of cosmological perturbations. We
propose an estimator for the bispectrum that is appropriate in the flat sky
approximation, apply it to the MAXIMA-1 data and evaluate errors using
bootstrap methods. We compare the estimated value with what would be expected
if the sky signal were Gaussian and find that it is indeed consistent, with a
per degree of freedom of approximately unity. This measurement places
constraints on models of inflation.Comment: 5 pages, 2 figures. New version to match paper accepted for
publication in Phys. Rev. Lett. Non-diagonal terms included leading to new
limits on f_N
Self-organisation and psychotherapy
Neste artigo, resultado de uma pesquisa de tipo qualitativo, hermenêutico e documental, procuramos mostrar como as Ciências Cognitivas, desde a sua constituição, têm contribuído para a compreensão do ser humano. Fazemos referência às visões mais racionalistas da mente, que a entendem semelhante a um sistema computacional, até à visão menos (não) racionalista que lhe confere valor cognitivo, envolta em emoções e afetos, que numa visão mais construtivista – ou pós-racionalista – se diria que traduz significados, traduz uma vivência ou uma história narrativa (e) pessoal. Assim, apresentamos o modelo de terapia cognitiva pós-racionalista de Vittorio Guidano, refletindo sobre os fundamentos epistemológicos do Movimento da Auto-organização (MAO), nos quais ele se fundamenta. Descrevemos sumariamente os alicerces epistemológicos do MAO, os quais garantem a este modelo uma dimensão holista e explicativa do processo de construção da identidade humana, que pode ser descrita como processo de conhecimento, capaz de vivenciar e ao mesmo tempo perceber e avaliar a sua própria experiência (autoconsciência).
O ser humano age na intersubjetividade, num mundo pluralista, com os seus congéneres, partilhando experiências e interpretando ações (complexificando-se através desses acoplamentos). Pretendemos, também, ilustrar que a matriz de funcionamento interno de cada ser humano, a qual lhe permite ordenar essa múltipla e facetada realidade, assim como formar/construir/ordenar significados pessoais, é o vínculo emotivo-afetivo.In this paper, which is the result of a qualitative, hermeneutical and documental research, we intend to show how the Cognitive Sciences, since their beginning,
have contributed to the understanding of human beings. We refer to the rationalistic understanding
of the mind (the mind is like a computer system), and also to the non-rationalistic understanding,
which attributes to the mind a cognitive value, immersed in emotions and affections. In addition, according to a constructivist or post-rationalistic understanding, the mind translates meanings, an experience or a personal narrative story. Thus, we present the model of post-rationalistic cognitive therapy of Vittorio Guidano, reflecting on the epistemological
foundations of the Self-Organization Movement, on which it is based. We describe briefly the epistemological principles of the Self-Organization Movement, which give to this model a holistic and explanatory dimension of the process of construction of human identity. This identity can be described as the human beings’ process of self-knowledge, as we are capable of experiencing and at the same time perceiving and evaluating, our own experiences (self-consciousness). The human being acts on intersubjectivity, in a pluralistic world with his peers, sharing experiences and interpreting actions. We also want to illustrate that the matrix of inner functioning of every human being, which allows us to sort this multi-faceted reality in a single personal order, is the emotional bond.(undefined
Determining Foreground Contamination in CMB Observations: Diffuse Galactic Emission in the MAXIMA-I Field
Observations of the CMB can be contaminated by diffuse foreground emission
from sources such as Galactic dust and synchrotron radiation. In these cases,
the morphology of the contaminating source is known from observations at
different frequencies, but not its amplitude at the frequency of interest for
the CMB. We develop a technique for accounting for the effects of such emission
in this case, and for simultaneously estimating the foreground amplitude in the
CMB observations. We apply the technique to CMB data from the MAXIMA-1
experiment, using maps of Galactic dust emission from combinations of IRAS and
DIRBE observations, as well as compilations of Galactic synchrotron emission
observations. The spectrum of the dust emission over the 150--450 GHz observed
by MAXIMA is consistent with preferred models but the effect on CMB power
spectrum observations is negligible.Comment: 19 pages, 8 figures, accepted for publication in the Astrophysical
Journal. Monor changes to match the published versio
Making Maps Of The Cosmic Microwave Background: The MAXIMA Example
This work describes Cosmic Microwave Background (CMB) data analysis
algorithms and their implementations, developed to produce a pixelized map of
the sky and a corresponding pixel-pixel noise correlation matrix from time
ordered data for a CMB mapping experiment. We discuss in turn algorithms for
estimating noise properties from the time ordered data, techniques for
manipulating the time ordered data, and a number of variants of the maximum
likelihood map-making procedure. We pay particular attention to issues
pertinent to real CMB data, and present ways of incorporating them within the
framework of maximum likelihood map-making. Making a map of the sky is shown to
be not only an intermediate step rendering an image of the sky, but also an
important diagnostic stage, when tests for and/or removal of systematic effects
can efficiently be performed. The case under study is the MAXIMA data set.
However, the methods discussed are expected to be applicable to the analysis of
other current and forthcoming CMB experiments.Comment: Replaced to match the published version, only minor change
Frequentist Estimation of Cosmological Parameters from the MAXIMA-1 Cosmic Microwave Background Anisotropy Data
We use a frequentist statistical approach to set confidence intervals on the
values of cosmological parameters using the MAXIMA-1 and COBE measurements of
the angular power spectrum of the cosmic microwave background. We define a
statistic, simulate the measurements of MAXIMA-1 and COBE,
determine the probability distribution of the statistic, and use it and the
data to set confidence intervals on several cosmological parameters. We compare
the frequentist confidence intervals to Bayesian credible regions. The
frequentist and Bayesian approaches give best estimates for the parameters that
agree within 15%, and confidence interval-widths that agree within 30%. The
results also suggest that a frequentist analysis gives slightly broader
confidence intervals than a Bayesian analysis. The frequentist analysis gives
values of \Omega=0.89{+0.26\atop -0.19}, \Omega_{\rm B}h^2=0.026{+0.020\atop
-0.011} and n=1.02{+0.31\atop -0.10}, and the Bayesian analysis gives values of
\Omega=0.98{+0.14\atop -0.19}, \Omega_{\rm B}h^2=0.0.029{+0.015\atop-0.010},
and , all at the 95% confidence level.Comment: 10 pages, 9 Postscript figures, changes made to reflect published
versio
MAXIMA: an experiment to measure temperature anisotropy in the cosmic microwave background
We describe the MAXIMA experiment, a balloon-borne measurement designed to
map temperature anisotropy in the Cosmic Microwave Background (CMB) over a wide
range of angular scales (multipole range 80 < l < 800). The experiment consists
of a 1.3 m diameter off-axis Gregorian telescope and a receiver with a 16
element array of bolometers cooled to 100 mK. The frequency bands are centered
at 150, 240, and 410 GHz. The 10' FWHM beam sizes are well matched to the scale
of acoustic peaks expected in the angular power spectrum of the CMB. The first
flight of the experiment in its full configuration was launched in August 1998.
A 122 sq-deg map of the sky was made near the Draco constellation during the 7
hour flight in a region of extremely low galactic dust contamination. This map
covers 0.3% of the sky and has 3200 independent beamsize pixels. We describe
the MAXIMA instrument and its performance during the recent flight.Comment: To appear in proceedings of `3K Cosmology', ed. F Melchiorri,
Conference held Oct 5-10 1998, Rome, 13 pages LaTeX (using aipproc2.sty &
aipproc2.cls), Postscript with higher resolution graphics available at
http://cfpa.berkeley.edu/group/cmb/gen.htm
Relics of cosmological quark-hadron phase transition
We propose that the amplified density fluctuations by the vanishing sound
velocity effect during the cosmological quark-hadron phase transition lead to
quark-gluon plasma lumps decoupled from the expansion of the universe, which
may evolve to quark nuggets (QNs). Assuming power-law spectrum of density
fluctuations, we investigate the parameter ranges for the QNs to play the role
of baryonic dark matter and give inhomogeneities which could affect big-bang
nucleosynthesis within the observational bounds of CMBR anisotropy. The QNs can
give the strongest constraint ever found on the spectral index.Comment: REVTEX, 4 pages, 2 eps figure
Multiple Methods for Estimating the Bispectrum of the Cosmic Microwave Background with Application to the MAXIMA Data
We describe different methods for estimating the bispectrum of Cosmic
Microwave Background data. In particular we construct a minimum variance
estimator for the flat-sky limit and compare results with previously-studied
frequentist methods. Application to the MAXIMA dataset shows consistency with
primordial Gaussianity. Weak quadratic non-Gaussianity is characterised by a
tunable parameter , corresponding to non-Gaussianity at a level (ratio of non-Gaussian to Gaussian terms), and we find limits of
for the minimum-variance estimator and for the
usual frequentist estimator. These are the tightest limits on primordial
non-Gaussianity which include the full effects of the radiation transfer
function.Comment: 24 pages, 13 figure
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