8,175 research outputs found
Quantum dynamics of the avian compass
The ability of migratory birds to orient relative to the Earth's magnetic
field is believed to involve a coherent superposition of two spin states of a
radical electron pair. However, the mechanism by which this coherence can be
maintained in the face of strong interactions with the cellular environment has
remained unclear. This Letter addresses the problem of decoherence between two
electron spins due to hyperfine interaction with a bath of spin 1/2 nuclei.
Dynamics of the radical pair density matrix are derived and shown to yield a
simple mechanism for sensing magnetic field orientation. Rates of dephasing and
decoherence are calculated ab initio and found to yield millisecond coherence
times, consistent with behavioral experiments
Development program for 35 watt traveling-wave tube space amplifier Final report, 30 Jun. 1967 - 30 Sep. 1969
Development of 35-watt, S band, traveling wave tube amplifier for Saturn 5 instrument uni
Cartesian Bicategories II
The notion of cartesian bicategory, introduced by Carboni and Walters for
locally ordered bicategories, is extended to general bicategories. It is shown
that a cartesian bicategory is a symmetric monoidal bicategory
Information and Opportunistic Behavior in Federal Crop Insurance Programs
Opportunistic behavior in crop insurance can arise due to asymmetric information between producers and the Federal Crop Insurance Corporation. Producers who insure fields using transitional yields based on county average yields or who select options such as buy-up coverage or revenue insurance may increase their return from crop insurance. Using field-level crop insurance contract data for several crops in five growing regions, we find evidence that producers can profit from using buy-up coverage, revenue insurance, and transitional yields and that the level of producer opportunism is crop but not necessarily land-quality specific and is greater due to premium subsidization.opportunistic behavior, crop insurance, buy-up, revenue, transitional yields
The Effects of Transitional Yields on Adverse Selection in Crop Insurance
Transitional yields based on county average can be used by producers as the basis to obtain crop insurance on fields that have not previously produced the crop. Using field-level crop insurance contract data for several crops in five different growing regions we examine the impact of this asymmetric information on adverse selection. Our results indicate that adverse selection does exist from the use of transitional yields and that it is crop specific but not land-quality specific.adverse selection, crop insurance, transitional yields, Risk and Uncertainty, Q18,
Are Male Employees Promoted More Often Than Females Who Are Just As Qualified?
The purpose of this research is to determine if males are promoted faster than females who are equally qualified. Statistics based on empirical studies have shown that from the number of students who have pursued degrees from the undergraduate level to the master’s level, females outnumber males by far. One can therefore only conclude (all things being equal) that academically there are more qualified females than males in the workplace. However when you look on companies’ corporate websites, there are more males than females in top management positions. Data were collected from a sample of 130 professionals who varied by gender, age, education, work experience and minority or majority status. The results of this study demonstrate that gender discrimination is not a perceptual barrier in promotional opportunities. Implications for manager and employees are discussed
Topological entanglement entropy in the second Landau level
The entanglement entropy of the incompressible states of a realistic quantum
Hall system in the second Landau level are studied by direct diagonalization.
The subdominant term to the area law, the topological entanglement entropy,
which is believed to carry information about topologic order in the ground
state, was extracted for filling factors nu = 12/5 and nu = 7/3. While it is
difficult to make strong conclusions about nu = 12/5, the nu = 7/3 state
appears to be very consistent with the topological entanglement entropy for the
k=4 Read-Rezayi state. The effect of finite thickness corrections to the
Coulomb potential used in the direct diagonalization are also systematically
studied.Comment: 5 pages, 4 figure
Gut immune dysfunction through impaired innate pattern recognition receptor expression and gut microbiota dysbiosis in chronic SIV infection.
HIV targets the gut mucosa early in infection, causing immune and epithelial barrier dysfunction and disease progression. However, gut mucosal sensing and innate immune signaling through mucosal pattern recognition receptors (PRRs) during HIV infection and disease progression are not well defined. Using the simian immunodeficiency virus (SIV)-infected rhesus macaque model of AIDS, we found a robust increase in PRRs and inflammatory cytokine gene expression during the acute SIV infection in both peripheral blood and gut mucosa, coinciding with viral replication. PRR expression remained elevated in peripheral blood following the transition to chronic SIV infection. In contrast, massive dampening of PRR expression was detected in the gut mucosa, despite the presence of detectable viral loads. Exceptionally, expression of Toll-like receptor 4 (TLR4) and TLR8 was downmodulated and diverged from expression patterns for most other TLRs in the gut. Decreased mucosal PRR expression was associated with increased abundance of several pathogenic bacterial taxa, including Pasteurellaceae members, Aggregatibacter and Actinobacillus, and Mycoplasmataceae family. Early antiretroviral therapy led to viral suppression but only partial maintenance of gut PRRs and cytokine gene expression. In summary, SIV infection dampens mucosal innate immunity through PRR dysregulation and may promote immune activation, gut microbiota changes, and ineffective viral clearance
Rigorous confidence intervals for critical probabilities
We use the method of Balister, Bollobas and Walters to give rigorous 99.9999%
confidence intervals for the critical probabilities for site and bond
percolation on the 11 Archimedean lattices. In our computer calculations, the
emphasis is on simplicity and ease of verification, rather than obtaining the
best possible results. Nevertheless, we obtain intervals of width at most
0.0005 in all cases
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