66,557 research outputs found
Autism genetics: searching for specificity and convergence.
Advances in genetics and genomics have improved our understanding of autism spectrum disorders. As many genes have been implicated, we look to points of convergence among these genes across biological systems to better understand and treat these disorders
Mitigating Inadequate Security Claims Through Effective Security Measures
Gaming and hospitality operators are currently facing a litigation crisis. Recent court decisions, such as Tailhook, have established that hospitality operators are responsible for foreseeable security problems. Because of the increased responsibility placed on gaming and hospitality operators to provide a safe and secure environment for their guests, patrons, and employees, companies must take a proactive stance regarding security. While the surveillance and security programs in place at most gaming establishments are often quite sophisticated, care must still be taken to remain current with technological advances in security and changing industry security standards. The implementation of security measures can help mitigate costs associated with inadequate security claims. A cost/benefit analysis can help quantify whether a proposed security measure is se
Conclusive and arbitrarily perfect quantum state transfer using parallel spin chain channels
We suggest a protocol for perfect quantum communication through spin chain
channels. By combining a dual-rail encoding with measurements only at the
receiving end, we can get conclusively perfect state transfer, whose
probability of success can be made arbitrarily close to unity. As an example of
such an amplitude delaying channel, we show how two parallel Heisenberg spin
chains can be used as quantum wires. Perfect state transfer with a probability
of failure lower than P in a Heisenberg chain of N spin-1/2 particles can be
achieved in a timescale of the order of N^1.7|ln(P)|. We demonstrate that our
scheme is more robust to decoherence and non-optimal timing than any scheme
using single spin chains.Comment: 6 pages, 4 figures ; expanded version inluding discussion of
transmission tim
Estimates of rates for dissociative recombination of NO + e via various mechanisms
We estimate rates for the dissociative recombination (DR) of NO +
e. Although accurate excited state potential energy curves for the excited
states of the neutral are not available, we estimate that the 1 {\Phi}
and the 1 {\Pi} states of the neutral may intersect the ground state
cation potential energy surface near its equilibrium geometry. Using fixed
nuclei scattering calculations we estimate the rate for direct DR via these
states and find it to be significant. We also perform approximate calculations
of DR triggered by the indirect mechanism, which suggest that the indirect DR
rate for NO is insignificant compared to the direct rate.Comment: Submitted to Phys Rev
Properties and stabilization of an extracellular α-glucosidase from the extremely thermophilic archaebacteria Thermococcus strain AN 1: enzyme activity at 130°C
An extracellular α-glucosidase from the thermophilic archaebacterium Thermococcus strain AN1 was purified 875-fold in five steps (Hiload Q-Sepharose, phenyl Sepharose, HPHT-hydroxyapatite, gel filtration and Mono Q chromatography) with a yield of 4%. It is a monomer with a molecular mass of about 60 kDa and a pI around 5. At 98°C, the purified enzyme in buffer has a half-life around 35 min, which is increased to around 215 min in presence of l% (w/v) dithiothreitol and 1% (w/v) BSA. Dithiothreitol (1%, w/v) and BSA (0.4%, w/v) also substantially increase the enzyme activity. The Km at 75°C is 0.41 mM with pNP-α- -glucopyranoside as substrate. The substrate preference of the enzyme is: pNP-α-D-glucoside > nigerose > panose > palatinose > isomaltose > maltose and turanose. No activity was found against starch, pullulan, amylose, maltotriose, maltotetraose, isomaltotriose, cellobiose and β-gentiobiose. A variety of techniques including immobilization (e.g., on epoxy and glass beads), chemical modification (cross- and cocross-linking) and the use of additives (including polyhydroxylic molecules, BSA, salts, etc.) were applied to enhance stability at temperatures above 100°C. The half-life could be increased from about 4 min at 110°C to 30–60 min at 130°C in presence of 90% (w/v) sorbitol, 1% (w/v) dithiothreitol and l% (w/v) BSA, and by cocross-linking with BSA in the presence of 90% (w/v) sorbitol. The stabilized enzyme showed good activity at 130°C
Labeling Policies in Food Markets: Private Incentives, Public Intervention, and Welfare Effects
This study considers the welfare impact of labeling policies of agricultural commodities with specific characteristics. Using a model of vertical differentiation, the effects on equilibrium and welfare levels are calculated. The introduction of the regulation and the emergence of two differentiated competitive markets leaves consumers and high-quality producers better off, while low-quality producers are worse off. With high costs and low quality differences, the total welfare impact of the regulation can be negative. Findings show that when high-quality producers can exercise market power, the regulation could be more easily accepted by producers, but it would have a negative effect on consumers.asymmetric information, food markets, labeling, market power, vertical differentiation, welfare effects, Agricultural and Food Policy,
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