29,994 research outputs found
Multiple Gluon Effects in at FNAL Energies: Semi-Analytical Results
We apply our Yennie-Frautschi-Suura exponentiated cross section formulas for
the parton processes q + {^(} \bar q {^)}{^\prime} \ra q{^\prime}{^\prime} +
{^(} \bar q {^)}{^\prime}{^\prime}{^\prime} + n(G) to the process q + \bar q
\ra t + \bar t + n(G) at FNAL energies, where G is a QCD gluon. We use
semi-analytical methods to compute the ratio ,
where is our soft gluon YFS exponentiated cross section and
is the Born cross section. For TeV, we get
, respectively, for for example. These results are
not inconsistent with the recent observations by CDF and D0.Comment: 6 pages, latex replaces postscript at archiver's reques
KEY FACTORS CONTRIBUTING TO COW/CALF COSTS, PROFITS AND PRODUCTION
In this study, cow/calf Standardized Performance Analysis (SPA) data for Texas, Oklahoma, and New Mexico are used to analyze how total cost, production, and profitability are affected by management choices. Total cost is the financial cost associated with raising a calf through the weaning stage; profits are measured using the rate of return on assets; production is determined by pounds weaned per exposed female. Variables such as herd size, pounds of feed fed, calving percentage, death loss, length of breeding season and investment in asset groups are used in regressions. Key factors contributing to a cow/calf operation's costs, production, and profitability are identified.Livestock Production/Industries,
Supersymmetric sigma models and the 't Hooft instantons
Witten's linear sigma model for ADHM instantons possesses a natural
supersymmetry. We study generalizations of the infrared limit of the model that
are invariant under supersymmetry. In the case of four space-time
dimensions a background with a conformally flat metric and torsion is required.
The geometry is specified by a single real scalar function satisfying Laplace's
equation. It gives rise to 't Hooft instantons for the gauge group ,
instead of the general ADHM instantons for an gauge group in the case
.Comment: 11 pages, Latex fil
A Conserved Functional Domain of Drosophila Coracle Is Required for Localization at the Septate Junction and Has Membrane-organizing Activity
This is the published version, also available here: http://dx.doi.org/10.1083/jcb.140.6.1463.The protein 4.1 superfamily is comprised of a diverse group of cytoplasmic proteins, many of which have been shown to associate with the plasma membrane via binding to specific transmembrane proteins. Coracle, a Drosophila protein 4.1 homologue, is required during embryogenesis and is localized to the cytoplasmic face of the septate junction in epithelial cells. Using in vitro mutagenesis, we demonstrate that the amino-terminal 383 amino acids of Coracle define a functional domain that is both necessary and sufficient for proper septate junction localization in transgenic embryos. Genetic mutations within this domain disrupt the subcellular localization of Coracle and severely affect its genetic function, indicating that correct subcellular localization is essential for Coracle function. Furthermore, the localization of Coracle and the transmembrane protein Neurexin to the septate junction display an interdependent relationship, suggesting that Coracle and Neurexin interact with one another at the cytoplasmic face of the septate junction. Consistent with this notion, immunoprecipitation and in vitro binding studies demonstrate that the amino-terminal 383 amino acids of Coracle and cytoplasmic domain of Neurexin interact directly. Together these results indicate that Coracle provides essential membrane-organizing functions at the septate junction, and that these functions are carried out by an amino-terminal domain that is conserved in all protein 4.1 superfamily members
Using zoo welfare assessments to identify common issues in developing country zoos
Zoo animal welfare is a high priority for many institutions worldwide, with modern zoos now ensuring that animals are housed and cared for to the highest standards. However, in countries where this knowledge is not as available or understood, standards may be lower. The aim of this research was to investigate if there were common zoo welfare concerns across developing country zoos. Wild Welfare is a charity working globally to improve welfare for zoo animals and has an independent welfare audit that is carried out before any intervention occurs. The Wild Welfare Audit, consisting of 110 questions, covering nine topics, was completed at 11 zoos in seven developing countries (Brazil, Egypt, Libya, Indonesia, Thailand, Malaysia and Vietnam) following a Likert scale score (1-3). A principal component analysis was also performed to evaluate the audit questions. The results suggest that common areas of concern were animal behaviour, positive animal mental states and human health and safety. These themes were likely due to the lack knowledge and understanding that may be linked to historical and cultural differences. This research has helped to revise the welfare audit as well as inform future intervention strategies for improving developing country zoo animal welfare
Second Harmonic Coherent Driving of a Spin Qubit in a Si/SiGe Quantum Dot
We demonstrate coherent driving of a single electron spin using second
harmonic excitation in a Si/SiGe quantum dot. Our estimates suggest that the
anharmonic dot confining potential combined with a gradient in the transverse
magnetic field dominates the second harmonic response. As expected, the Rabi
frequency depends quadratically on the driving amplitude and the periodicity
with respect to the phase of the drive is twice that of the fundamental
harmonic. The maximum Rabi frequency observed for the second harmonic is just a
factor of two lower than that achieved for the first harmonic when driving at
the same power. Combined with the lower demands on microwave circuitry when
operating at half the qubit frequency, these observations indicate that second
harmonic driving can be a useful technique for future quantum computation
architectures.Comment: 9 pages, 9 figure
A programmable two-qubit quantum processor in silicon
With qubit measurement and control fidelities above the threshold of
fault-tolerance, much attention is moving towards the daunting task of scaling
up the number of physical qubits to the large numbers needed for fault tolerant
quantum computing. Here, quantum dot based spin qubits may offer significant
advantages due to their potential for high densities, all-electrical operation,
and integration onto an industrial platform. In this system, the
initialisation, readout, single- and two-qubit gates have been demonstrated in
various qubit representations. However, as seen with other small scale quantum
computer demonstrations, combining these elements leads to new challenges
involving qubit crosstalk, state leakage, calibration, and control hardware
which provide invaluable insight towards scaling up. Here we address these
challenges and demonstrate a programmable two-qubit quantum processor in
silicon by performing both the Deutsch-Josza and the Grover search algorithms.
In addition, we characterise the entanglement in our processor through quantum
state tomography of Bell states measuring state fidelities between 85-89% and
concurrences between 73-80%. These results pave the way for larger scale
quantum computers using spins confined to quantum dots
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