4,957 research outputs found
Restructuring the Philippine Statistical System in Response to New Challenges
For a national statistical system to continue to be useful and relevant to its clients and the general public, it has to occasionally undergo an exhaustive evaluation of its performance according to certain parameters. The Philippine statistical system had recently gone through such process. This Policy Notes provides a summary of the findings and recommendations of the evaluation.statistical system, Philippine Statistical System (PSS)
Observations of microquasars with the MAGIC telescope
We report on the results from the observations in very high energy band (VHE,
E_gamma > 100GeV) of the black hole X-ray binary (BHXB) Cygnus X-1. The
observations were performed with the MAGIC telescope, for a total of 40 hours
during 26 nights, spanning the period between June and November 2006. We report
on the results of the searches for steady and variable gamma-ray signals,
including the first experimental evidence for an intense flare, of duration
between 1.5 and 24 hours.Comment: Contribution to the 30th ICRC, Merida Mexico, July 2007 on behalf of
the MAGIC Collaboratio
Separable Measurement Estimation of Density Matrices and its Fidelity Gap with Collective Protocols
We show that there exists a gap between the performance of separable and
collective measurements in qubit mixed-state estimation that persists in the
large sample limit. We characterize such gap in terms of the corresponding
bounds on the mean fidelity. We present an adaptive protocol that attains the
separable-measurement bound. This (optimal separable) protocol uses von Neumann
measurements and can be easily implemented with current technology.Comment: version published in PR
Asterias: a parallelized web-based suite for the analysis of expression and aCGH data
Asterias (\url{http://www.asterias.info}) is an integrated collection of
freely-accessible web tools for the analysis of gene expression and aCGH data.
Most of the tools use parallel computing (via MPI). Most of our applications
allow the user to obtain additional information for user-selected genes by
using clickable links in tables and/or figures. Our tools include:
normalization of expression and aCGH data; converting between different types
of gene/clone and protein identifiers; filtering and imputation; finding
differentially expressed genes related to patient class and survival data;
searching for models of class prediction; using random forests to search for
minimal models for class prediction or for large subsets of genes with
predictive capacity; searching for molecular signatures and predictive genes
with survival data; detecting regions of genomic DNA gain or loss. The
capability to send results between different applications, access to additional
functional information, and parallelized computation make our suite unique and
exploit features only available to web-based applications.Comment: web based application; 3 figure
Chandra Observations of the Gamma-ray Binary LSI+61303: Extended X-ray Structure?
We present a 50 ks observation of the gamma-ray binary LSI+61303 carried out
with the ACIS-I array aboard the Chandra X-ray Observatory. This is the highest
resolution X-ray observation of the source conducted so far. Possible evidence
of an extended structure at a distance between 5 and 12 arcsec towards the
North of LSI+61303 have been found at a significance level of 3.2 sigma. The
asymmetry of the extended emission excludes an interpretation in the context of
a dust-scattered halo, suggesting an intrinsic nature. On the other hand, while
the obtained source flux, of F_{0.3-10 keV}=7.1^{+1.8}_{-1.4} x 10^{-12}
ergs/cm^2/s, and hydrogen column density, N_{H}=0.70+/-0.06 x 10^{22} cm^{-2},
are compatible with previous results, the photon index Gamma=1.25+/-0.09 is the
hardest ever found. In light of these new results, we briefly discuss the
physics behind the X-ray emission, the location of the emitter, and the
possible origin of the extended emission ~0.1 pc away from LSI+61303.Comment: 4 pages, 3 figures. Accepted for publication in ApJ Letter
No surviving evolved companions to the progenitor of supernova SN 1006
Type Ia supernovae are thought to occur as a white dwarf made of carbon and
oxygen accretes sufficient mass to trigger a thermonuclear explosion. The
accretion could occur slowly from an unevolved (main-sequence) or evolved
(subgiant or giant) star, that being dubbed the single-degenerate
channel, or rapidly as it breaks up a smaller orbiting white dwarf (the double-
degenerate channel). Obviously, a companion will survive the explosion
only in the single-degenerate channel. Both channels might contribute to
the production of type Ia supernovae but their relative proportions
still remain a fundamental puzzle in astronomy. Previous searches for remnant
companions have revealed one possible case for SN 1572, though that has
been criticized. More recently, observations have restricted surviving
companions to be small, main-sequence stars, ruling out giant
companions, though still allowing the single-degenerate channel. Here we report
the result of a search for surviving companions to the progenitor of SN
1006. None of the stars within 4' of the apparent site of the explosion
is associated with the supernova remnant, so we can firmly exclude all giant
and subgiant companions to the progenitor. Combined with the previous results,
less than 20 per cent of type Iae occur through the single degenerate channel.Comment: Published as a letter in Nature (2012 September 27
A discrete invitation to quantum filtering and feedback control
The engineering and control of devices at the quantum-mechanical level--such
as those consisting of small numbers of atoms and photons--is a delicate
business. The fundamental uncertainty that is inherently present at this scale
manifests itself in the unavoidable presence of noise, making this a novel
field of application for stochastic estimation and control theory. In this
expository paper we demonstrate estimation and feedback control of quantum
mechanical systems in what is essentially a noncommutative version of the
binomial model that is popular in mathematical finance. The model is extremely
rich and allows a full development of the theory, while remaining completely
within the setting of finite-dimensional Hilbert spaces (thus avoiding the
technical complications of the continuous theory). We introduce discretized
models of an atom in interaction with the electromagnetic field, obtain
filtering equations for photon counting and homodyne detection, and solve a
stochastic control problem using dynamic programming and Lyapunov function
methods.Comment: 76 pages, 12 figures. A PDF file with high resolution figures can be
found at http://minty.caltech.edu/papers.ph
Conteúdo de noradrenalina do hipotálamo e tronco-encefálico de ratos inoculados com Trypanosoma Cruzi
Noradrenaline was assayed fluorimetrically in the hypothalamus and brainstem of rats killed 20 and 32 days after inoculation with the Y strain of T. cruzi (300,000 trypomastigotes i.p.). In these animals and their normal controls the right atrial appendages were submitted to the glyoxilic acid fluorescence technique for the demonstration of noradrenergic nerves. The noradrenaline content of the brain-stem and hypothalamus of the infected animals was not significantly different from that of controls. In the atrial appendages, however, an almost complete noradrenergic denervation was observed. This result indicates that the mechanism involved in neuronal lesion in Chagas'disease discriminates between peripheral and central noradrenergic neurons.O conteúdo de noradrenalina do hipotálamo e do tronco encefálico de ratos controle e inoculados com a cepa Y (300.000 tripomastigotas, i.p.) de Trypanosoma cruzi foi medido pela técnica fluorimétrica de Anton e Sayre. Os animais foram sacrificados 20 e 32 dias depois da inoculação. Para avaliação do grau de desnervação simpática do coração dos animais infectados, a aurícula direita foi observada com microscópio de fluorescência após tratamento histoquímieo pela técnica do ácido glioxílico. O conteúdo de noradrenalina do hipotálamo e do tronco encefálico dos animais infectados não diferiu do medido nos animais controle. Contudo, um quase completo desaparecimento das fibras adrenérgicas foi observado no coração dos animais chagásicos, sugerindo que o mechanismo envolvido na lesão discrimina neurônios adrenérgicos centrais e periféricos
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