884 research outputs found
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Biologic surveys for the Sandia National Laboratories, Coyote Canyon Test Complex, Kirtland Air Force Base, Albuquerque, New Mexico
This report provides results of a comprehensive biologic survey performed in Coyote Canyon Test Complex (CCTC), Sandia National Laboratories (SNL), Bernalillo County, New Mexico, which was conducted during the spring and summer of 1992 and 1993. CCTC is sited on land owned by the Department of Energy (DOE) and Kirtland Air Force Base and managed by SNL. The survey covered 3,760 acres of land, most of which is rarely disturbed by CCTC operations. Absence of grazing by livestock and possibly native ungulates, and relative to the general condition of private range lands throughout New Mexico, and relative to other grazing lands in central New Mexico. Widely dispersed, low intensity use by SNL as well as prohibition of grazing has probably contributed to abundance of special status species such as grama grass cactus within the CCTC area. This report evaluates threatened and endangered species found in the area, as well as comprehensive assessment of biologic habitats. Included are analyses of potential impacts and mitigative measures designed to reduce or eliminate potential impacts. Included is a summary of CCTC program and testing activities
The economics of phosphorus supplementation of beef cattle grazing northern Australian rangelands
Context: Phosphorus (P) deficiency occurs in beef cattle grazing many rangeland regions with low-P soils, including in northern Australia, and may severely reduce cattle productivity in terms of growth, reproductive efficiency and mortality. However, adoption of effective P supplementation by cattle producers in northern Australia is low. This is likely to be due to lack of information and understanding of the profitability of P supplementation where cattle are P-deficient.
Aims: The profitability of P supplementation was evaluated for two dissimilar regions of northern Australia, namely (1) the Katherine region of the Northern Territory, and (2) the Fitzroy Natural Resource Management (NRM) region of central Queensland.
Methods: Property-level, regionally relevant herd models were used to determine whole-of-business productivity and profitability over 30 years. The estimated costs and benefits of P supplementation were obtained from collation of experimental data and expert opinion of persons with extensive experience of the industry. The economic consequences of P supplementation at the property level were assessed by comparison of base production without P supplementation with the expected production of P-supplemented herds, and included the implementation phase and changes over time in herd structure. In the Katherine region, it was assumed that the entire cattle herd (breeders and growing cattle) grazed acutely P-deficient land types and the consequences of (1) no P supplementation, or P supplementation during (2) the dry season, or (3) both the wet and dry seasons (i.e. 3 scenarios) were evaluated. In the Fitzroy NRM region, it was assumed that only the breeders grazed P-deficient land types with three categories of P deficiency (marginal, deficient and acutely deficient), each with either (1) no P supplementation, or P supplementation during (2) the wet season, (3) the dry season, or (4) both the wet and dry seasons (i.e. 12 scenarios).
Key results: In the Katherine region, year-round P supplementation of the entire cattle herd (7400 adult equivalents) grazing acutely P-deficient pasture resulted in a large increase in annual business profit (+AU200 000. In the Fitzroy NRM region, P supplementation during any season of the breeder herd grazing deficient or acutely P-deficient pastures increased profit by +AU45 000/annum (total cattle herd 1500 adult equivalents). Importantly, P supplementation during the wet season-only resulted in the greatest increases in profit within each category of P deficiency, comprising +AU6300 and AU$45 000 additional profit per annum for marginal, deficient and acutely P-deficient herds respectively.
Conclusions: The large economic benefits of P supplementation for northern beef enterprises estimated in the present study substantiate the current industry recommendation that effective P supplementation is highly profitable when cattle are grazing P-deficient land types.
Implications: The contradiction of large economic benefits of P supplementation and the generally low adoption rates by the cattle industry in northern Australia suggests a need for targeted research and extension to identify the specific constraints to adoption, including potential high initial capital costs
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Accuracy of finite-element models for the stress analysis of multiple-holed moderator blocks
Two steps have been taken to quantify and improve the accuracy in the analysis. First, the limitations of various approximation techniques have been studied with the aid of smaller benchmark problems containing fewer holes. Second, a new family of computer programs has been developed for handling such large problems. This paper describes the accuracy studies and the benchmark problems. A review is given of some proposed modeling techniques including local mesh refinement, homogenization, a special-purpose finite element, and substructuring. Some limitations of these approaches are discussed. The new finite element programs and the features that contribute to their efficiency are discussed. These include a standard architecture for out-of-core data processing and an equation solver that operates on a peripheral array processor. The central conclusions of the paper are: (1) modeling approximation methods such as local mesh refinement and homogenization tend to be unreliable, and they should be justified by a fine mesh benchmark analysis; and (2) finite element codes are now available that can achieve accurate solutions at a reasonable cost, and there is no longer a need to employ modeling approximations in the two-dimensional analysis of HTGR fuel elements. 10 figures
The development of metaphorical language comprehension in typical development and in Williams syndrome
The domain of figurative language comprehension was used to probe the developmental relation between language and cognition in typically developing individuals and individuals with Williams syndrome. Extending the work of Vosniadou and Ortony, the emergence of nonliteral similarity and category knowledge was investigated in 117 typically developing children between 4 and 12 years of age, 19 typically developing adults, 15 children with Williams syndrome between 5 and 12 years of age, and 8 adults with Williams syndrome. Participants were required to complete similarity and categorization statements by selecting one of two words (e.g., either “The sun is like ___” or “The sun is the same kind of thing as ___”) with word pairs formed from items that were literally, perceptually, or functionally similar to the target word or else anomalous (e.g., moon, orange, oven, or chair, respectively). Results indicated that individuals with Williams syndrome may access different, less abstract knowledge in figurative language comparisons despite the relatively strong verbal abilities found in this disorder
Automorphism groups of polycyclic-by-finite groups and arithmetic groups
We show that the outer automorphism group of a polycyclic-by-finite group is
an arithmetic group. This result follows from a detailed structural analysis of
the automorphism groups of such groups. We use an extended version of the
theory of the algebraic hull functor initiated by Mostow. We thus make
applicable refined methods from the theory of algebraic and arithmetic groups.
We also construct examples of polycyclic-by-finite groups which have an
automorphism group which does not contain an arithmetic group of finite index.
Finally we discuss applications of our results to the groups of homotopy
self-equivalences of K(\Gamma, 1)-spaces and obtain an extension of
arithmeticity results of Sullivan in rational homotopy theory
How spiking neurons give rise to a temporal-feature map
A temporal-feature map is a topographic neuronal representation of temporal attributes of phenomena or objects that occur in the outside world. We explain the evolution of such maps by means of a spike-based Hebbian learning rule in conjunction with a presynaptically unspecific contribution in that, if a synapse changes, then all other synapses connected to the same axon change by a small fraction as well. The learning equation is solved for the case of an array of Poisson neurons. We discuss the evolution of a temporal-feature map and the synchronization of the single cells’ synaptic structures, in dependence upon the strength of presynaptic unspecific learning. We also give an upper bound for the magnitude of the presynaptic interaction by estimating its impact on the noise level of synaptic growth. Finally, we compare the results with those obtained from a learning equation for nonlinear neurons and show that synaptic structure formation may profit
from the nonlinearity
Same-sign W pair production as a probe of double parton scattering at the LHC
We study the production of same-sign W boson pairs at the LHC in double
parton interactions. Compared with simple factorised double parton
distributions (dPDFs), we show that the recently developed dPDFs, GS09, lead to
non-trivial kinematic correlations between the W bosons. A numerical study of
the prospects for observing this process using same-sign dilepton signatures,
including same-sign WWjj, di-boson and heavy flavour backgrounds, at 14 TeV
centre-of-mass energy is then performed. It is shown that a small excess of
same-sign dilepton events from double parton scattering over a background
dominated by single scattering WZ(gamma*) production could be observed at the
LHC.Comment: 14 pages, 8 figures. Added references, slight changes in the text
The Spin-Dependent Structure Functions of Nuclei in the Meson-Nucleon Theory
A theoretical approach to the investigation of spin-dependent structure
functions in deep inelastic scattering of polarized leptons off polarized
nuclei, based on the effective meson-nucleon theory and operator product
expansion method, is proposed and applied to deuteron and . The explicit
forms of the moments of the deuteron and spin-dependent structure
functions are found and numerical estimates of the influence of nuclear
structure effects are presented.Comment: 42 pages revtex, 7 postscript figures available from above e-mail
upon request. Perugia preprint DFUPG 92/9
From core collapse to superluminous: The rates of massive stellar explosions from the Palomar Transient Factory
We present measurements of the local core-collapse supernova (CCSN) rate using SN discoveries from the Palomar Transient Factory (PTF). We use a Monte Carlo simulation of hundreds of millions of SN light-curve realizations coupled with the detailed PTF survey detection efficiencies to forward model the SN rates in PTF. Using a sample of 86 CCSNe, including 26 stripped-envelope SNe (SESNe), we show that the overall CCSN volumetric rate is CCv=9.10-1.27+1.56× 10-5SNe yr-1Mpc-3, h703 at za = 0.028, and the SESN volumetric rate is SEv=2.41-0.64+0.81× 10-5SNe yr-1Mpc-3, h703. We further measure a volumetric rate for hydrogen-free superluminous SNe (SLSNe-I) using eight events at z ≤ 0.2 of SLSN-Iv=35-13+25 SNe yr-1Gpc-3, h703, which represents the most precise SLSN-I rate measurement to date. Using a simple cosmic star formation history to adjust these volumetric rate measurements to the same redshift, we measure a local ratio of SLSN-I to SESN of ∼1/810+1500-94, and of SLSN-I to all CCSN types of ∼1/3500+2800-720. However, using host galaxy stellar mass as a proxy for metallicity, we also show that this ratio is strongly metallicity dependent: in low-mass (logM∗ < 9.5 M·) galaxies, which are the only environments that host SLSN-I in our sample, we measure an SLSN-I to SESN fraction of 1/300+380-170 and 1/1700+1800-720 for all CCSN. We further investigate the SN rates a function of host galaxy stellar mass, and show that the specific rates of all CCSNe decrease with increasing stellar mass
CP asymmetries in the supersymmetric trilepton signal at the LHC
In the CP-violating Minimal Supersymmetric Standard Model, we study the
production of a neutralino-chargino pair at the LHC. For their decays into
three leptons, we analyze CP asymmetries which are sensitive to the CP phases
of the neutralino and chargino sector. We present analytical formulas for the
entire production and decay process, and identify the CP-violating
contributions in the spin correlation terms. This allows us to define the
optimal CP asymmetries. We present a detailed numerical analysis of the cross
sections, branching ratios, and the CP observables. For light neutralinos,
charginos, and squarks, the asymmetries can reach several 10%. We estimate the
discovery potential for the LHC to observe CP violation in the trilepton
channel.Comment: 39 pages, 8 figures, version to appear in EPJC, discussion(s) added,
typo in (D.79), (D.118) corrected, new Fig. 7; The European Physical Journal
C, Volume 72, Issue 3, 201
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