650 research outputs found
Geology of the Sharp Mountain Area, Southern Part of the Bear River Range, Utah
The Sharp Mountain area is situated in the southern part of the Bear River Range in Utah. The geology of the Bear River Range to the north of this area, in Utah and Idaho, has been mapped; however, prior to this study little was known about the Sharp Mountain area. The purpose of this investigation are as follows: (1) to map and describe the geology of the area, and (2) to relate the stratigraphic and structural features of the Sharp Mountain area to those of the surrounding region
Great Balls of FIRE III: Modeling Black Hole Mergers from Massive Star Clusters in Simulations of Galaxies
After the nearly hundred gravitational-wave detections reported by the
LIGO-Virgo-KAGRA Collaboration, the question of the cosmological origin of
merging binary black holes (BBHs) remains open. The two main formation channels
generally considered are from isolated field binaries or via dynamical assembly
in dense star clusters. Here, we focus on understanding the dynamical formation
of merging BBHs within massive clusters in galaxies of different masses. To
this end, we apply a new framework to consistently model the formation and
evolution of massive star clusters in zoom-in cosmological simulations of
galaxies. Each simulation, taken from the FIRE project, provides a realistic
star formation environment with a unique star formation history and hosts
realistic giant molecular clouds that constitute the birthplace of star
clusters. Combined with the code for star cluster evolution CMC, we are able to
produce populations of dynamically formed merging BBHs across cosmic time in
different environments. As the most massive star clusters preferentially form
in dense massive clouds of gas, we find that, despite their low metallicities
favourable to the creation of black holes, low-mass galaxies contain few
massive clusters and therefore have a limited contribution to the global
production of dynamically formed merging BBHs. Furthermore, we find that
massive clusters can host hierarchical BBH mergers with clear identifiable
physical properties. Looking at the evolution of the BBH merger rate in
different galaxies, we find strong correlations between BBH mergers and the
most extreme episodes of star formation. Finally, we discuss the implications
for future LIGO-Virgo-KAGRA gravitational wave observations.Comment: 14 pages, 9 figures, 3 table
Comparing predictive abilities of longitudinal child growth models
© 2018 John Wiley & Sons, Ltd. The Bill and Melinda Gates Foundation's Healthy Birth, Growth and Development knowledge integration project aims to improve the overall health and well-being of children across the world. The project aims to integrate information from multiple child growth studies to allow health professionals and policy makers to make informed decisions about interventions in lower and middle income countries. To achieve this goal, we must first understand the conditions that impact on the growth and development of children, and this requires sensible models for characterising different growth patterns. The contribution of this paper is to provide a quantitative comparison of the predictive abilities of various statistical growth modelling techniques based on a novel leave-one-out validation approach. The majority of existing studies have used raw growth data for modelling, but we show that fitting models to standardised data provide more accurate estimation and prediction. Our work is illustrated with an example from a study into child development in a middle income country in South America
Upper Limit on the Prompt Muon Flux Derived from the LVD Underground Experiment
We present the analysis of the muon events with all muon multiplicities
collected during 21804 hours of operation of the first LVD tower. The measured
depth-angular distribution of muon intensities has been used to obtain the
normalization factor, A, the power index, gamma, of the primary all-nucleon
spectrum and the ratio, R_c, of prompt muon flux to that of pi-mesons - the
main parameters which determine the spectrum of cosmic ray muons at the sea
level. The value of gamma = 2.77 +/- 0.05 (68% C.L.) and R_c < 2.0 x 10^-3 (95%
C.L.) have been obtained. The upper limit to the prompt muon flux favours the
models of charm production based on QGSM and the dual parton model.Comment: 10 pages, 4 figures, RevTex. To appear in Phys. Rev.
Muon `Depth -- Intensity' Relation Measured by LVD Underground Experiment and Cosmic-Ray Muon Spectrum at Sea Level
We present the analysis of the muon events with all muon multiplicities
collected during 21804 hours of operation of the first LVD tower. The measured
angular distribution of muon intensity has been converted to the `depth --
vertical intensity' relation in the depth range from 3 to 12 km w.e.. The
analysis of this relation allowed to derive the power index, , of the
primary all-nucleon spectrum: . The `depth -- vertical
intensity' relation has been converted to standard rock and the comparison with
the data of other experiments has been done. We present also the derived
vertical muon spectrum at sea level.Comment: 7 pages, 3 figures, to be published on Phys. Rev.
Characterizing mass, momentum, energy and metal outflow rates of multi-phase galactic winds in the FIRE-2 cosmological simulations
We characterize mass, momentum, energy and metal outflow rates of multi-phase
galactic winds in a suite of FIRE-2 cosmological "zoom-in" simulations from the
Feedback in Realistic Environments (FIRE) project. We analyze simulations of
low-mass dwarfs, intermediate-mass dwarfs, Milky Way-mass halos, and
high-redshift massive halos. Consistent with previous work, we find that dwarfs
eject about 100 times more gas from their interstellar medium (ISM) than they
form in stars, while this mass "loading factor" drops below one in massive
galaxies. Most of the mass is carried by the hot phase ( K) in massive
halos and the warm phase ( K) in dwarfs; cold outflows ( K)
are negligible except in high-redshift dwarfs. Energy, momentum and metal
loading factors from the ISM are of order unity in dwarfs and significantly
lower in more massive halos. Hot outflows have higher specific
energy than needed to escape from the gravitational potential of dwarf halos;
indeed, in dwarfs, the mass, momentum, and metal outflow rates increase with
radius whereas energy is roughly conserved, indicating swept up halo gas.
Burst-averaged mass loading factors tend to be larger during more powerful star
formation episodes and when the inner halo is not virialized, but we see
effectively no trend with the dense ISM gas fraction. We discuss how our
results can guide future controlled numerical experiments that aim to elucidate
the key parameters governing galactic winds and the resulting associated
preventative feedback.Comment: Accepted to MNRAS with minor revisions, main body is 25 pages with 14
figure
Syndromic surveillance: STL for modeling, visualizing, and monitoring disease counts
<p>Abstract</p> <p>Background</p> <p>Public health surveillance is the monitoring of data to detect and quantify unusual health events. Monitoring pre-diagnostic data, such as emergency department (ED) patient chief complaints, enables rapid detection of disease outbreaks. There are many sources of variation in such data; statistical methods need to accurately model them as a basis for timely and accurate disease outbreak methods.</p> <p>Methods</p> <p>Our new methods for modeling daily chief complaint counts are based on a seasonal-trend decomposition procedure based on loess (STL) and were developed using data from the 76 EDs of the Indiana surveillance program from 2004 to 2008. Square root counts are decomposed into inter-annual, yearly-seasonal, day-of-the-week, and random-error components. Using this decomposition method, we develop a new synoptic-scale (days to weeks) outbreak detection method and carry out a simulation study to compare detection performance to four well-known methods for nine outbreak scenarios.</p> <p>Result</p> <p>The components of the STL decomposition reveal insights into the variability of the Indiana ED data. Day-of-the-week components tend to peak Sunday or Monday, fall steadily to a minimum Thursday or Friday, and then rise to the peak. Yearly-seasonal components show seasonal influenza, some with bimodal peaks.</p> <p>Some inter-annual components increase slightly due to increasing patient populations. A new outbreak detection method based on the decomposition modeling performs well with 90 days or more of data. Control limits were set empirically so that all methods had a specificity of 97%. STL had the largest sensitivity in all nine outbreak scenarios. The STL method also exhibited a well-behaved false positive rate when run on the data with no outbreaks injected.</p> <p>Conclusion</p> <p>The STL decomposition method for chief complaint counts leads to a rapid and accurate detection method for disease outbreaks, and requires only 90 days of historical data to be put into operation. The visualization tools that accompany the decomposition and outbreak methods provide much insight into patterns in the data, which is useful for surveillance operations.</p
Measurement of Dijet Angular Distributions at CDF
We have used 106 pb^-1 of data collected in proton-antiproton collisions at
sqrt(s)=1.8 TeV by the Collider Detector at Fermilab to measure jet angular
distributions in events with two jets in the final state. The angular
distributions agree with next to leading order (NLO) predictions of Quantum
Chromodynamics (QCD) in all dijet invariant mass regions. The data exclude at
95% confidence level (CL) a model of quark substructure in which only up and
down quarks are composite and the contact interaction scale is Lambda_ud(+) <
1.6 TeV or Lambda_ud(-) < 1.4 TeV. For a model in which all quarks are
composite the excluded regions are Lambda(+) < 1.8 TeV and Lambda(-) < 1. 6
TeV.Comment: 16 pages, 2 figures, 2 tables, LaTex, using epsf.sty. Submitted to
Physical Review Letters on September 17, 1996. Postscript file of full paper
available at http://www-cdf.fnal.gov/physics/pub96/cdf3773_dijet_angle_prl.p
Search for charged Higgs decays of the top quark using hadronic tau decays
We present the result of a search for charged Higgs decays of the top quark,
produced in collisions at 1.8 TeV. When the charged
Higgs is heavy and decays to a tau lepton, which subsequently decays
hadronically, the resulting events have a unique signature: large missing
transverse energy and the low-charged-multiplicity tau. Data collected in the
period 1992-1993 at the Collider Detector at Fermilab, corresponding to
18.70.7~pb, exclude new regions of combined top quark and charged
Higgs mass, in extensions to the standard model with two Higgs doublets.Comment: uuencoded, gzipped tar file of LaTeX and 6 Postscript figures; 11 pp;
submitted to Phys. Rev.
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