We provide upper bounds for the cardinality of the value set of a polynomial map in several variables over a finite field. These bounds generalize earlier bounds for univariate polynomials. © 2012 The author 2012. Published by Oxford University Press. All rights reserved.

Interstitial pulmonary fibrosis induced by intratracheal instillation of bleomycin (BL) involves an excess production of reactive oxygen species, unavailability of adequate levels of NAD and ATP to repair the injured pulmonary epithelium, and an overexuberant lung collagen reactivity followed by deposition of highly cross-linked mature collagen fibrils resistant to enzymatic degradation. In the present study, we have demonstrated that dietary supplementation with taurine and niacin offered almost complete protection against the lung fibrosis in a multidose BL hamster model. The mechanisms for the protective effect of taurine and niacin are multifaceted. These include the ability of taurine to scavenge HOCl and stabilize the biomembrane; niacin's ability to replenish the BL-induced depletion of NAD and ATP; and the combined effect of taurine and niacin to suppress all aspects of BL-induced increases in the lung collagen reactivity, a hallmark of interstitial pulmonary fibrosis. It was concluded from the data presented at this Conference that the combined treatment with taurine and niacin, which offers a multipronged approach, will have great therapeutic potential in the intervention of the development of chemically induced interstitial lung fibrosis in animals and humans.

In correlated electron materials, electrons often self-organize and form a variety of patterns with potential ordering of charges, spins, and orbitals, which are believed to be closely connected to many novel properties of these materials including superconductivity, metal-insulator transitions, and the CMR effect. How these real-space patterns affect the conductivity and other properties of materials (which are usually described in momentum space) is one of the major challenges of modern condensed matter physics. Moreover, although the presence of static stripes is indisputable, the existence (and potential impacts) of fluctuating stripes in such compounds is a subject of great debate. Here we present the electronic excitations of La$_{2-2x}$Sr$_{1+2x}$Mn$_{2}$O$_{7}$ (x ~ 0.59) probed by angle-resolved photoemission (ARPES), from which we demonstrate that a novel type of ordering, termed bi-stripes, can exhibit either static or fluctuating order as a function of temperature. We found that the static bi-stripe order is especially damaging to electrical conductivity, completely localizing the electrons in the bi-stripe regions, while the fluctuating stripes can coexist with mobile carriers. This physics drives a novel phase transition with colossal conductivity changes as a function of temperature. Our finding suggests that quantum stripes can give rise to electronic properties significantly different from their static counterparts. Inducing transition between them can turn on remarkable electronic phenomena, enriching our understanding of correlated electron systems as well as opening a window for potential applications in electronic devices.

Hepatitis B virus (HBV) is a major etiological factor of hepatocellular carcinoma (HCC). However, the precise pathogenetic mechanisms linking HBV infection and HCC remain uncertain. It has been reported that decreased antioxidant enzyme activities are asso

Objective

To compare daily exposure to tuberculosis (TB) patients between HIV-infected and non-HIV-infected health care workers (HCWs), and examine the uptake of antiretroviral therapy (ART) and isoniazid preventive therapy (IPT) among HIV-infected HCWs in Botswana.

Design

We conducted a cross-sectional study among HCWs in 30 hospitals and clinics. We determined self-reported exposure frequency to TB patients and HIV status through in-person interviews. HCWs with unknown or negative HIV status were offered rapid HIV testing. Multivariable Poisson regression modeling with robust variance was used to estimate the association between HIV status and daily exposure to TB patients.

Results

Of 1877 participants enrolled, 1388 (73.9%) with complete data were included in this study. Among 277 (20.0%) HIV-infected participants, 14.3% were newly diagnosed, 57.8% were on ART, and 34.3% reported previously receiving IPT. Daily exposure to TB patients was reported by respectively 48.4% and 52.9% of HIV-infected and non-infected participants. After adjusting for sex, age, occupation, and department, the rates of daily TB exposure remained similar between HIV-infected and non-HIV-infected participants (prevalence ratio 0.96, 95%CI 0.85-1.08).

Conclusions

We found similar rates of exposure to TB patients between HIV-infected and non-HIV-infected HCWs. Improved efforts are needed to reduce nosocomial exposure to TB among HIV-infected HCWs.

Light soaking is found to increase the specific heat C and internal friction Q−1 of pure (a-Si) and hydrogenated (a-Si:H) amorphous silicon. At the lowest temperatures, the increases in C and Q−1 are consistent with an increased density of two-level systems (TLS). The light-induced increase in C persists to room temperature. Neither the sound velocity nor shear modulus change with light soaking indicating that the Debye specific heat is unchanged which suggests that light soaking creates localized vibrational modes in addition to TLS. The increase can be reversibly added and removed by light soaking and annealing, respectively, suggesting that it is related to the Staebler-Wronski effect (SWE), even in a-Si without H, and involves a reversible nanoscale structural rearrangement that is facilitated by, but does not require, H to occur.

Specific heat measurements from 2 to 300 K of hydrogenated amorphous silicon prepared by hot-wire chemical vapor deposition show a large excess specific heat at low temperature, significantly larger than the Debye specific heat calculated from the measured sound velocity. The as-prepared films have a Schottky anomaly that is associated with metastable hydrogen in the amorphous network, as well as large linear and excess cubic term commonly associated with tunneling two-level systems in amorphous solids. Annealing at 200 °C, a temperature that enables hydrogen mobility but not evaporation, irreversibly reduces the heat capacity, eliminating the Schottky anomaly and leaving a reduced linear heat capacity. A non-monotonic dependence on growth temperature and H content is observed in all effects, except for sound velocity, which suggests that the tunneling two-level systems and the Schottky anomaly are associated with atomic hydrogen and require low density regions to form, while sound velocity is associated with the silicon network and increases with increasing growth temperature.