12,813 research outputs found
Toxicity of materials in fire situations: Laboratory data obtained at the University of San Francisco
Approximately 300 materials were evaluated using a specific set of test conditions. Materials tested included wood, fibers, fabrics and synthetic polymers. Data obtained using 10 different sets of test conditions are presented
Uncertainties of predictions from parton distribution functions II: the Hessian method
We develop a general method to quantify the uncertainties of parton
distribution functions and their physical predictions, with emphasis on
incorporating all relevant experimental constraints. The method uses the
Hessian formalism to study an effective chi-squared function that quantifies
the fit between theory and experiment. Key ingredients are a recently developed
iterative procedure to calculate the Hessian matrix in the difficult global
analysis environment, and the use of parameters defined as components along
appropriately normalized eigenvectors. The result is a set of 2d Eigenvector
Basis parton distributions (where d=16 is the number of parton parameters) from
which the uncertainty on any physical quantity due to the uncertainty in parton
distributions can be calculated. We illustrate the method by applying it to
calculate uncertainties of gluon and quark distribution functions, W boson
rapidity distributions, and the correlation between W and Z production cross
sections.Comment: 30 pages, Latex. Reference added. Normalization of Hessian matrix
changed to HEP standar
Computing Fast and Reliable Gravitational Waveforms of Binary Neutron Star Merger Remnants
Gravitational waves have been detected from the inspiral of a binary
neutron-star, GW170817, which allowed constraints to be placed on the neutron
star equation of state. The equation of state can be further constrained if
gravitational waves from a post-merger remnant are detected. Post-merger
waveforms are currently generated by numerical-relativity simulations, which
are computationally expensive. Here we introduce a hierarchical model trained
on numerical-relativity simulations, which can generate reliable post-merger
spectra in a fraction of a second. Our spectra have mean fitting factors of
0.95, which compares to fitting factors of 0.76 and 0.85 between different
numerical-relativity codes that simulate the same physical system. This method
is the first step towards generating large template banks of spectra for use in
post-merger detection and parameter estimation.Comment: Submitted to PRL. 6 pages, 4 figure
Contours and Contouring in Hydrography Part II - Interpolation
In Part I of this series, the authors discussed those issues which we feel are fundamentally important and which must be addressed by any method which aims to mechanize the drawing of depth contours for hydrographic charts. In this article we begin the discussion of the How of contouring. In particular, we concentrate on some of the most common methods used in the interpolation of the synthetic surface upon which computed contours will lie
Active Carbon and Oxygen Shell Burning Hydrodynamics
We have simulated 2.5 s of the late evolution of a star with full hydrodynamic behavior. We present the first simulations
of a multiple-shell burning epoch, including the concurrent evolution and
interaction of an oxygen and carbon burning shell. In addition, we have evolved
a 3D model of the oxygen burning shell to sufficiently long times (300 s) to
begin to assess the adequacy of the 2D approximation. We summarize striking new
results: (1) strong interactions occur between active carbon and oxygen burning
shells, (2) hydrodynamic wave motions in nonconvective regions, generated at
the convective-radiative boundaries, are energetically important in both 2D and
3D with important consequences for compositional mixing, and (3) a spectrum of
mixed p- and g-modes are unambiguously identified with corresponding adiabatic
waves in these computational domains. We find that 2D convective motions are
exaggerated relative to 3D because of vortex instability in 3D. We discuss the
implications for supernova progenitor evolution and symmetry breaking in core
collapse.Comment: 5 pages, 4 figures in emulateapj format. Accepted for publication in
ApJ Letters. High resolution figure version available at
http://spinach.as.arizona.ed
Impacts of Forage Cropping Decisions on Feed-Flows in Cool- Temperate Grazing Systems
Intensive cool-temperate grasslands often rely on adding forage crops to help supply feed when pasture growth is limited by cool temperatures and low sunlight. We tested the impacts of using single- or multi-graze crops to alter feed supply in either summer/autumn or winter on productivity in red deer farming systems in a cool-temperate environment. The choice of single-graze or multi-graze crops to provide forage in deer grazing systems had an impact on the feed flows and the amount of pasture available, with multi-graze crops supplying more feed during the dry summer months while single-graze crops supplying more feed during the cool winter months. The limited growth rates of young red deer, and the late calving of hinds meant that pasture covers could be low during the late winter and early spring without compromising animal production. Overall, the use of a multi-graze crop, especially when used early in autumn to promote weaner liveweight gain, increased overall productivity by 5% and increased feed conversion efficiency by 2.5% in the venison production system
The Effect of Certain Chemical Treatments on Photolytic Image Formation
A study of certain chemical baths and combinations of chemical baths was made to determine their effect on the print-out image of a specially-prepared conventional developing-out enlarging paper. These Print-out images were formed and made visible entirely from the photolytic effect of the image exposure. Arc lamp, tungsten lamp and electronic flash lamp exposures were made; arc lamp exposures were the most satisfactory. The chemical associated with the most image improvement was stannous chloride
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