908 research outputs found
Prediction and Generation of Binary Markov Processes: Can a Finite-State Fox Catch a Markov Mouse?
Understanding the generative mechanism of a natural system is a vital
component of the scientific method. Here, we investigate one of the fundamental
steps toward this goal by presenting the minimal generator of an arbitrary
binary Markov process. This is a class of processes whose predictive model is
well known. Surprisingly, the generative model requires three distinct
topologies for different regions of parameter space. We show that a previously
proposed generator for a particular set of binary Markov processes is, in fact,
not minimal. Our results shed the first quantitative light on the relative
(minimal) costs of prediction and generation. We find, for instance, that the
difference between prediction and generation is maximized when the process is
approximately independently, identically distributed.Comment: 12 pages, 12 figures;
http://csc.ucdavis.edu/~cmg/compmech/pubs/gmc.ht
Large-Scale CO Maps of the Lupus Molecular Cloud Complex
Fully sampled degree-scale maps of the 13CO 2-1 and CO 4-3 transitions toward
three members of the Lupus Molecular Cloud Complex - Lupus I, III, and IV -
trace the column density and temperature of the molecular gas. Comparison with
IR extinction maps from the c2d project requires most of the gas to have a
temperature of 8-10 K. Estimates of the cloud mass from 13CO emission are
roughly consistent with most previous estimates, while the line widths are
higher, around 2 km/s. CO 4-3 emission is found throughout Lupus I, indicating
widespread dense gas, and toward Lupus III and IV. Enhanced line widths at the
NW end and along the edge of the B228 ridge in Lupus I, and a coherent velocity
gradient across the ridge, are consistent with interaction between the
molecular cloud and an expanding HI shell from the Upper-Scorpius subgroup of
the Sco-Cen OB Association. Lupus III is dominated by the effects of two HAe/Be
stars, and shows no sign of external influence. Slightly warmer gas around the
core of Lupus IV and a low line width suggest heating by the
Upper-Centaurus-Lupus subgroup of Sco-Cen, without the effects of an HI shell.Comment: 54 pages, 27 figures, 5 tables. To appear in ApJS. Preprint also
available (with full-size figures) from
http://www.astro.ex.ac.uk/people/nfht/publications.html Datacubes available
from http://www.astro.ex.ac.uk/people/nfht/resources.htm
Promotion of social skills promotion in preschool children
Social skills promotion in the child's relationships, in a preventive level, provides the development of and improvement in social competence, resulting in greater adaptability to the social environment. This research aimed to verify the effectiveness of a preventive program of social skills development in children between 4 and 6 years old and their parents. The results reflect the performance of 9 children of both sexes, with age between 5 and 6 years. CBCL (Achenbach, 1991) was used as the analysis instrument, answered by parents about the children's behaviors, before and after the participation in the program. Based on this analysis, it was possible to observe that there is a statistical difference between CBCL results before and after intervention, indicating changes in parents' perception about their children's behaviors and the probable increase in behaviors that facilitate social interaction.A promoção de habilidades sociais nas relações da criança, a um nível preventivo, proporciona o desenvolvimento e melhoria da competência social, resultando em maior adaptabilidade ao meio social. Esta pesquisa teve por objetivo verificar a eficácia de um programa preventivo de desenvolvimento de habilidades sociais em crianças de 4 a 6 anos e seus pais. Os resultados refletem o desempenho de 9 crianças, de ambos os sexos, com idade entre 5 e 6 anos. Como instrumento de análise utilizou-se o Child Behavior Check-List (CBCL), respondido pelos pais em relação aos comportamentos dos filhos, antes e após a participação do programa. A partir desta análise, foi possível observar que existe uma diferença estatística entre os resultados do CBCL pré e pós-intervenção, indicando mudanças na percepção dos comportamentos das crianças pelos pais e provável aumento dos comportamentos facilitadores de interação social
The ZEUS Forward Plug Calorimeter with Lead-Scintillator Plates and WLS Fiber Readout
A Forward Plug Calorimeter (FPC) for the ZEUS detector at HERA has been built
as a shashlik lead-scintillator calorimeter with wave length shifter fiber
readout. Before installation it was tested and calibrated using the X5 test
beam facility of the SPS accelerator at CERN. Electron, muon and pion beams in
the momentum range of 10 to 100 GeV/c were used. Results of these measurements
are presented as well as a calibration monitoring system based on a Co
source.Comment: 38 pages (Latex); 26 figures (ps
Global Survey on Pancreatic Surgery During the COVID-19 Pandemic
This global survey among members of seven international pancreatic associations and study groups elucidates the role of pancreatic surgery during the COVID-19 pandemic, regarding patient selection for the surgical and oncological treatment of pancreatic diseases to support clinical decision-making and creating a starting point for further discussion
Detection of the 205 um [NII] Line from the Carina Nebula
We report the first detection of the 205 um 3P1 - 3P0 [NII] line from a
ground-based observatory using a direct detection spectrometer. The line was
detected from the Carina star formation region using the South Pole Imaging
Fabry-Perot Interferometer (SPIFI) on the Antarctic Submillimeter Telescope and
Remote Observatory (AST/RO) at South Pole. The [NII] 205 um line strength
indicates a low-density (n ~ 32 cm^-3 ionized medium, similar to the
low-density ionized halo reported previously in its [OIII] 52 and 88 um line
emission. When compared with the ISO [CII] observations of this region, we find
that ~27% of the [CII] line emission arises from this low-density ionized gas,
but the large majority ~ 73% of the observed [CII] line emission arises from
the neutral interstellar medium. This result supports and underpins prior
conclusions that most of the observed [CII] 158 um line emission from Galactic
and extragalactic sources arises from the warm, dense photodissociated surfaces
of molecular clouds. The detection of the [NII] line demonstrates the utility
of Antarctic sites for THz spectroscopy.Comment: 8 pages, 2 figures. To appear in the Astrophysical Journal Letter
Measurement of the diffractive structure function in deep inelastic scattering at HERA
This paper presents an analysis of the inclusive properties of diffractive
deep inelastic scattering events produced in interactions at HERA. The
events are characterised by a rapidity gap between the outgoing proton system
and the remaining hadronic system. Inclusive distributions are presented and
compared with Monte Carlo models for diffractive processes. The data are
consistent with models where the pomeron structure function has a hard and a
soft contribution. The diffractive structure function is measured as a function
of \xpom, the momentum fraction lost by the proton, of , the momentum
fraction of the struck quark with respect to \xpom, and of . The \xpom
dependence is consistent with the form \xpoma where
in all bins of and
. In the measured range, the diffractive structure function
approximately scales with at fixed . In an Ingelman-Schlein type
model, where commonly used pomeron flux factor normalisations are assumed, it
is found that the quarks within the pomeron do not saturate the momentum sum
rule.Comment: 36 pages, latex, 11 figures appended as uuencoded fil
An NLO QCD analysis of inclusive cross-section and jet-production data from the ZEUS experiment
The ZEUS inclusive differential cross-section data from HERA, for charged and
neutral current processes taken with e+ and e- beams, together with
differential cross-section data on inclusive jet production in e+ p scattering
and dijet production in \gamma p scattering, have been used in a new NLO QCD
analysis to extract the parton distribution functions of the proton. The input
of jet data constrains the gluon and allows an accurate extraction of
\alpha_s(M_Z) at NLO;
\alpha_s(M_Z) = 0.1183 \pm 0.0028(exp.) \pm 0.0008(model)
An additional uncertainty from the choice of scales is estimated as \pm
0.005. This is the first extraction of \alpha_s(M_Z) from HERA data alone.Comment: 37 pages, 14 figures, to be submitted to EPJC. PDFs available at
http://durpdg.dur.ac.uk/hepdata in LHAPDFv
Measurement of event shapes in deep inelastic scattering at HERA
Inclusive event-shape variables have been measured in the current region of
the Breit frame for neutral current deep inelastic ep scattering using an
integrated luminosity of 45.0 pb^-1 collected with the ZEUS detector at HERA.
The variables studied included thrust, jet broadening and invariant jet mass.
The kinematic range covered was 10 < Q^2 < 20,480 GeV^2 and 6.10^-4 < x < 0.6,
where Q^2 is the virtuality of the exchanged boson and x is the Bjorken
variable. The Q dependence of the shape variables has been used in conjunction
with NLO perturbative calculations and the Dokshitzer-Webber non-perturbative
corrections (`power corrections') to investigate the validity of this approach.Comment: 7+25 pages, 6 figure
ZEUS Next-to-leading-order QCD Analysis of Data on Deep Inelastic Scattering
Next-to-leading-order QCD analyses of the ZEUS data on deep inelastic scattering together with fixed-target data have been performed, from which the gluon and quark densities of the proton and the value of the strong coupling constant (Formula presented) were extracted. The study includes a full treatment of the experimental systematic uncertainties including point-to-point correlations. The resulting uncertainties in the parton density functions are presented. A combined fit for (Formula presented) and the gluon and quark densities yields a value for (Formula presented) in agreement with the world average. The parton density functions derived from ZEUS data alone indicate the importance of HERA data in determining the sea quark and gluon distributions at low x. The limits of applicability of the theoretical formalism have been explored by comparing the fit predictions to ZEUS data at very low (Formula presented) © 2003 The American Physical Society
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