Matrix Elements From Moments of Correlation Functions

Momentum-space derivatives of matrix elements can be related to their coordinate-space moments through the Fourier transform. We derive these expressions as a function of momentum transfer Q^2 for asymptotic in/out states consisting of a single hadron. We calculate corrections to the finite volume moments by studying the spatial dependence of the lattice correlation functions. This method permits the computation of not only the values of matrix elements at momenta accessible on the lattice, but also the momentum-space derivatives, providing a priori information about the Q^2 dependence of form factors. As a specific application we use the method, at a single lattice spacing and with unphysically heavy quarks, to directly obtain the slope of the isovector form factor at various Q^2, whence the isovector charge radius. The method has potential application in the calculation of any hadronic matrix element with momentum transfer, including those relevant to hadronic weak decays

Renal function, uraemia and early arteriovenous fistula failure

Background Guidance varies regarding the optimal timing of arteriovenous fistula (AVF) creation. The aim of this study was to evaluate the association between uraemia, haemodialysis and early AVF failure. Methods Immunoblotting and cell proliferation assays were performed on vascular smooth muscle cells (VSM) cells isolated from long saphenous vein samples to evaluate the cells’ ability to proliferate when stimulated with uraemic (post-dialysis) and hyperuraemic (pre-dialysis) serum. Clinical data was collected prospectively for 569 consecutive radiocephalic (RCF) and brachiocephalic (BCF) fistulae. The primary outcome was AVF failure at 6 weeks. Dialysis status (haemodialysis (HD); pre-dialysis (Pre-D)), eGFR and serum urea were evaluated to determine if they affected early AVF failure. Results Human VSM cells demonstrated increased capacity to proliferate when stimulated with hyperuraemic serum. There was no significant difference in early failure rate of either RCF or BCF depending on dialysis status (pre-D RCF 31.4% (n = 188); pre-D BCF 22.4% (n = 165); HD RCF 29.3% (n = 99); HD BCF 25.9% (n = 116); p = 0.34). There was no difference in mean eGFR between those patients with early AVF failure and those without (11.2+/-0.2 ml/min/1.73 m2 vs. 11.6+/-0.4 ml/min/1.73 m2; p = 0.47). Uraemia was associated with early AVF failure (serum urea: 35.0+/-0.7 mg/dl vs. 26.6+/-0.3 mg/dl (p &lt; 0.001)). Conclusions We present the first in vivo evidence of an association between adverse early AVF outcomes and uraemia. This is supported mechanistically by in vitro work demonstrating a pro-mitogenic effect of hyperuraemic serum. We hypothesise that uraemia-driven upregulation of VSM cell proliferation at the site of surgical insult in contributes to higher early AVF failure rates.</p

An Analysis of the Banana Import market in the U.S.

Demand, banana, import, market power, Demand and Price Analysis, Food Consumption/Nutrition/Food Safety,

Avalanche noise characteristics of single Al/sub x/Ga/sub 1-x/As(0.3

Avalanche multiplication and excess noise have been measured on a series of Al/sub x/Ga/sub 1-x/As-GaAs and GaAs-Al/sub x/Ga/sub 1-x/As (x=0.3,0.45, and 0.6) single heterojunction p/sup +/-i-n/sup +/ diodes. In some devices excess noise is lower than in equivalent homojunction devices with avalanche regions composed of either of the constituent materials, the heterojunction with x=0.3 showing the greatest improvement. Excess noise deteriorates with higher values of x because of the associated increase in hole ionization in the Al/sub x/Ga/sub 1-x/As layer. It also depends critically upon the carrier injection conditions and Monte Carlo simulations show that this dependence results from the variation in the degree of noisy feedback processes on the position of the injected carriers

Loss of vesicular dopamine release precedes tauopathy in degenerative dopaminergic neurons in a Drosophila model expressing human tau.

While a number of genome-wide association studies have identified microtubule-associated protein tau as a strong risk factor for Parkinson's disease (PD), little is known about the mechanism through which human tau can predispose an individual to this disease. Here, we demonstrate that expression of human wild-type tau is sufficient to disrupt the survival of dopaminergic neurons in a Drosophila model. Tau triggers a synaptic pathology visualized by vesicular monoamine transporter-pHGFP that precedes both the age-dependent formation of tau-containing neurofibrillary tangle-like pathology and the progressive loss of DA neurons, thereby recapitulating the pathological hallmarks of PD. Flies overexpressing tau also exhibit progressive impairments of both motor and learning behaviors. Surprisingly, contrary to common belief that hyperphosphorylated tau could aggravate toxicity, DA neuron degeneration is alleviated by expressing the modified, hyperphosphorylated tau(E14). Together, these results show that impairment of VMAT-containing synaptic vesicle, released to synapses before overt tauopathy may be the underlying mechanism of tau-associated PD and suggest that correction or prevention of this deficit may be appropriate targets for early therapeutic intervention

Estimating the Fair Insurance Premium for Dungeness Crab Yields in the Western U.S. Coast

The Dungeness is a popular food and the most commercially important crab in the western states in the U.S. Like all agricultural production, the crab fisherman face yield risks and must manage these risks. In addition to weather risk, crab fisherman may experience low yields if the crabs are over fished in previous years. Farmers for many traditional agricultural crops can purchase crop insurance to insure against low yields. However, crab fishermen at this time do not have this option. The purpose of this paper is to estimate a fair insurance premium based on the historical yields of the Dungeness crab. This information can then be used in risk/return models for crab fishing to determine if it would be optimal for fisherman to purchase crop insurance. An important input into the fair insurance premium estimation is the yield distribution. Sherrick et al. estimated alternative yield distributions to evaluate traditional crop insurance. However, no one has looked at the yield distributions for the Dungeness crab nor explored possible crop insurance. Much of the past literature for the fishing industry has focused on production functions, cost function models, and optimal catching yields for specific fish species. Moreover, most research has focused on the endangered commercial ocean species such as tuna and swordfish. Data and Methodology This research collects the annual landing data including metric tons, pounds, and price per pound from NOAA's National Marine Fisheries Service (NOAA Fisheries Service) to analyze the yield distributions of Dungeness crab in California, Oregon, Washington, and Alaska from 1950 to 2009. Dickey Fuller test is conducted for each state to test if the data is stationary. The Durbin-Watson test was used to make sure the data did not have autocorrelation problems. We find that the detrended data has positive Skewness contrary to traditional crop yield data. The positive Skewness indicates that the tail on the right sides is longer than the left side and the mass of the distribution is concentrated on the left. It also has relatively few high values. The candidate distributions used include normal, Gamma, Weibull, logistic, lognormal, and loglogistic distributions. The fitted distributions are compared with formal goodness- of- fit tests including Chi-Square, Anderson-Darling, and Kolmogorov-Smirnov. The loglogistic distribution is best to estimate the yield losses of Alaska, Oregon, and California respectively while the logistic is best for Washington. The Gamma and normal distribution are the worst for the four states. Actual Production History (APH) policies insure crop producers against yield losses due to natural causes. After Just and Weninger found that crop yield losses were nonnormally distributed, many agricultural researchers use parametric (Goodwin and Ker) and nonparametric distributions (Sherrick et al) and the insured price to estimate the insurance premium. The premium refers to the periodic payment made on the insurance policy. When the yields are below the insured level (the predicted level each year), the insurance company has to pay indemnities to the producers to compensate them for their losses. Our study uses different parametric distributions to forecast the crab yields. Along with the yield distributions and yield forecasts, we assume that the crop insurance insures up to 80% of the yield distribution. We also assume that the insured price is the predicted price per pound for 2010 (since the price model are Pth-order autoregressive (AR(p)) processes) to estimate the fair insurance premium. The insured prices per pound of the four states from north to south are $1.88,$2.39, $1.94, and$1.99 respectively. If the random value (that the realized yields fall below the guaranteed yields) generated by the best distributions which may generate different parametric value for the four states falls below zero, it will means that the fisherman suffer yield losses, and that the insurance company has to compensate the fishermen’s revenue. The insurance company pays the fishermen the dollars that the insured price times 80% of the yield that the fishermen suffer from loss. The indemnities will be either zero or positive. Next, we adopt Latin hypercube sampling (LHS) to simulate the indemnities 500 times to calculate the average indemnities. If we don’t consider the capital and administration fees of the insurance company, the average indemnities will be the actuarially fair insurance premium. The average indemnity and thus the actuarially fair premiums of the overall crab industry are $1,380,924,$702,344, $2,823,855, and$3,470,998 one year for the all ships in Alaska, Washington, Oregon, and California respectively. Unlike traditional crop insurance that estimates the premium per acre, we use the total premium shared by all fishing vessels in the state and account for the total tons that the fishing vessels load because the crabs and the fishing vessel move everywhere. After simulated, half of the time the insurance company must pay indemnities. To avoid the high risk of yield losses and uncertainty, the existence of insurance is necessary to protect the fishermen’s revenue. Finally, we will try to use non-parametric method to estimate the fair premium and compare the results of the parametric and non-parametric distributions for the rigorous study. We will also estimate the potential welfare gain of fishermen from this insurance policy.Dungeness Crab, Fair Insurance Premium, Simulation, Agricultural and Food Policy, Agricultural Finance, Risk and Uncertainty,