Descreening of Field Effect in Electrically Gated Nanopores

This modeling work investigates the electrical modulation characteristics of field-effect gated nanopores. Highly nonlinear current modulations are observed in nanopores with non-overlapping electric double layers, including those with pore diameters 100 times the Debye screening length. We attribute this extended field-effect gating to a descreening effect, i.e. the counter-ions do not fully relax to screen the gating potential due to the presence of strong ionic transport

THE INFLUENCE OF SALMONELLA IN PIGS PRE-HARVEST ON SALMONELLA HUMAN HEALTH COSTS AND RISK FROM PORK

Salmonellosis in people is a costly disease, much of it occurring because of food associated exposure. We develop a farm-to-fork model which estimates the pork associated Salmonella risk and human health costs. This analysis focuses on the components of the pork production chain up to the point of producing a chilled pork carcass. Sensitivity and scenario analysis show that changes that occur in Salmonella status during processing are substantially more important for human health risk and have a higher benefit/cost ratio for application of strategies that control Salmonella compared with on-farm strategies.Food Consumption/Nutrition/Food Safety,

Preparing ground states of quantum many-body systems on a quantum computer

Preparing the ground state of a system of interacting classical particles is an NP-hard problem. Thus, there is in general no better algorithm to solve this problem than exhaustively going through all N configurations of the system to determine the one with lowest energy, requiring a running time proportional to N. A quantum computer, if it could be built, could solve this problem in time sqrt(N). Here, we present a powerful extension of this result to the case of interacting quantum particles, demonstrating that a quantum computer can prepare the ground state of a quantum system as efficiently as it does for classical systems.Comment: 7 pages, 1 figur

The X10 Flare on 2003 October 29: Triggered by Magnetic Reconnection between Counter-Helical Fluxes?

Vector magnetograms taken at Huairou Solar Observing Station (HSOS) and Mees Solar Observatory (MSO) reveal that the super active region (AR) NOAA 10486 was a complex region containing current helicity flux of opposite signs. The main positive sunspots were dominated by negative helicity fields, while positive helicity patches persisted both inside and around the main positive sunspots. Based on a comparison of two days of deduced current helicity density, pronounced changes were noticed which were associated with the occurrence of an X10 flare that peaked at 20:49 UT, 2003 October 29. The average current helicity density (negative) of the main sunspots decreased significantly by about 50. Accordingly, the helicity densities of counter-helical patches (positive) were also found to decay by the same proportion or more. In addition, two hard X-ray (HXR) `footpoints' were observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI} during the flare in the 50-100 keV energy range. The cores of these two HXR footpoints were adjacent to the positions of two patches with positive current helicity which disappeared after the flare. This strongly suggested that the X10 flare on 2003 Oct. 29 resulted from reconnection between magnetic flux tubes having opposite current helicity. Finally, the global decrease of current helicity in AR 10486 by ~50% can be understood as the helicity launched away by the halo coronal mass ejection (CME) associated with the X10 flare.Comment: Solar Physics, 2007, in pres

A unimodal sequence with mode at a quarter length

We show that the number $A(n,m)$ of partitions with $m$ even parts and largest hook length $n$ is strongly unimodal with mode [(n-1)/4] for $n\ge 6$. We establish this result by induction, using a $5$-term recurrence due to Lin, Xiong and Yan, and two $4$-term recurrences obtained by Zeilberger's algorithm. The sequence $A(n,m)$ is not log-concave. Using M\"obius transformation and the method of interlacing zeros, we obtain that every zero of every generating function $\sum_m A(n,m)z^m$ lies on the left half part of the circle |z-1|=2. Moreover, as a direct application of Wang and Zhang's characterization of root geometry of polynomial sequences that satisfy a recurrence of type $(1,1)$, we see that all these zeros are densely distributed on the half circle