The Weak Field Limit of the Magnetorotational Instability

We investigate the behavior of the magneto-rotational instability in the limit of extremely weak magnetic field, i.e., as the ratio of ion cyclotron frequency to orbital frequency (X) becomes small. Considered only in terms of cold two-fluid theory, instability persists to arbitrarily small values of X, and the maximum growth rate is of order the orbital frequency except for the range m_e/m_i < |X| < 1, where it can be rather smaller. In this range, field aligned with rotation (X > 0) produces slower growth than anti-aligned field (X < 0). The maximum growth rate is generally achieved at smaller and smaller wavelengths as |X| diminishes. When |X| < m_e/m_i, new unstable "electromagnetic-rotational" modes appear that do not depend on the equilibrium magnetic field. Because the most rapidly-growing modes have extremely short wavelengths when |X| is small, they are often subject to viscous or resistive damping, which can result in suppressing all but the longest wavelengths, for which growth is much slower. We find that this sort of damping is likely to curtail severely the frequently-invoked mechanism for cosmological magnetic field growth in which a magnetic field seeded by the Biermann battery is then amplified by the magneto-rotational instability. On the other hand, the small |X| case may introduce interesting effects in weakly-ionized disks in which dust grains carry most of the electric charge.Comment: 30 pages, including 4 figures; revised version resubmitted to Ap

Hypothalamic gene expression during voluntary hypophagia in the Sprague-Dawley rat on withdrawal of the palatable liquid diet, Ensure

Copyright © 2014 Elsevier Inc. All rights reserved.Peer reviewedPostprin

Enterprise profiles in deprived areas: Are they distinctive?

This paper examines the extent to which segmenting business activity on the basis of the relative deprivation of a given area provides additional understanding (in terms of analysis and policy) that is not obtained by alternative divisions, e.g., by sector, size, etc. The paper is primarily motivated by the explicit inclusion of a deprived area dimension to many UK small business/enterprise policies introduced since 1997. We use two datasets drawn from the customer records of Barclays Bank PLC to obtain an initial analysis of the business stocks and dynamics in deprived and non-deprived areas of England. The data indicate that the deprived areas of England vary systematically from the wider economy in terms of several business stock characteristics and associated dynamics. These differences include a lower proportion of business service firms, lower female involvement in the owner-manager base and a poorer risk profile. The analysis supports the view that there are likely to be benefits from the tailoring of small business/ enterprise policies to sub-national levels

Effect of magnetic fluctuations on the normal state properties of Sr_2RuO_4

We investigate the normal state transport properties of Sr$_2$RuO$_4$ and we show that a consistent explanation of the experimental results can be obtained assuming that the system is near a quantum phase transition. Within the framework of a self-consistent spin fluctuation theory, we calculate the temperature variation of some relevant physical quantities and we discuss a possible microscopic origin of the quantum phase transition.Comment: 5 pages, 4 figures, to appear on Europhysics Letter

Structural Changes in U.S. Agricultural Production and Productivity

Livestock Production/Industries,

A novel non-Fermi-liquid state in the iron-pnictide FeCrAs

We report transport and thermodynamic properties of stoichiometric single crystals of the hexagonal iron-pnictide FeCrAs. The in-plane resistivity shows an unusual "non-metallic" dependence on temperature T, rising continuously with decreasing T from ~ 800 K to below 100 mK. The c-axis resistivity is similar, except for a sharp drop upon entry into an antiferromagnetic state at T_N 125 K. Below 10 K the resistivity follows a non-Fermi-liquid power law, rho(T) = rho_0 - AT^x with x<1, while the specific heat shows Fermi liquid behaviour with a large Sommerfeld coefficient, gamma ~ 30 mJ/mol K^2. The high temperature properties are reminiscent of those of the parent compounds of the new layered iron-pnictide superconductors, however the T -> 0 properties suggest a new class of non-Fermi liquid.Comment: 6 pages, 4 figure

Targeting a therapeutic LIF transgene to muscle via the immune system ameliorates muscular dystrophy.

Many potentially&nbsp;therapeutic molecules have been identified for treating Duchenne muscular dystrophy. However, targeting those molecules only to sites of active pathology is an obstacle to their clinical use. Because dystrophic muscles become extensively inflamed, we tested whether expressing a therapeutic transgene in leukocyte progenitors that invade muscle would provide selective, timely delivery to diseased muscle. We designed a transgene in which leukemia inhibitory factor (LIF) is under control of a leukocyte-specific promoter and transplanted transgenic cells into dystrophic mice. Transplantation diminishes pathology, reduces Th2 cytokines in muscle and biases macrophages away from a CD163+/CD206+ phenotype that promotes fibrosis. Transgenic cells also abrogate TGFβ signaling, reduce fibro/adipogenic progenitor cells and reduce fibrogenesis of muscle cells. These findings indicate that leukocytes expressing a LIF transgene reduce fibrosis by suppressing type 2 immunity and highlight a novel application by which immune cells can be genetically modified as potential therapeutics to treat muscle disease

Determination of arsenic in a nickel alloy by flow injection hydride generation atomic absorption spectrometry

The development of a method for the direct determination of trace arsenic quantities in nickel alloy digests, by flow injection hydride generation atomic absorption spectrometry, is described. An optimization study of the manifold and chemical parameters produced system performance, in terms of tolerance of the nickel matrix and sensitivity, such that matrix removal and pre-reduction of As(V) to As (111) prior to arsine generation were eliminated. Full recovery of the As(V) signal from a solution containing 5 ng m1- 1 in the presence of 60 µg mJ- 1 nickel was obtained. Validation of the method was achieved by analyzing a British Chemical Standard (BCS) Certified Reference Material (CRM) #346 IN nickel alloy containing arsenic at a concentration of 50 µg g- 1• Following dissolution in nitric and hydrofluoric acids by a microwave assisted procedure, the only subsequent preparation required was dilution by the appropriate factor. Up to 60 injections h- 1 may be made, with a detection limit of 0.5 ng m1- 1 arsenic (250 pg absolute) as As(V) in a 500 µI sample. The peak height characteristic concentration is 0.46 ng m1- 1, with a relative standard deviation of 3.5% for a 10 ng m1- 1 As(V) standard (n= 6)