Impurity-assisted Andreev reflection at a spin-active half-metal-superconductor interface

The Andreev reflection amplitude at a clean interface between a half-metallic ferromagnet (H) and a superconductor (S) for which the half metal's magnetization has a gradient perpendicular to the interface is proportional to the excitation energy $\varepsilon$ and vanishes at $\varepsilon=0$ [B\'{e}ri {\em et al.}, Phys.\ Rev.\ B {\bf 79}, 024517 (2009)]. Here we show that the presence of impurities at or in the immediate vicinity of the HS interface leads to a finite Andreev reflection amplitude at $\varepsilon=0$. This impurity-assisted Andreev reflection dominates the low-bias conductance of a HS junction and the Josephson current of an SHS junction in the long-junction limit.Comment: 12 pages, 2 figure

Temperature dependent magnetic anisotropy in metallic magnets from an ab-initio electronic structure theory: L1_0-ordered FePt

On the basis of a first-principles, relativistic electronic structure theory of finite temperature metallic magnetism, we investigate the variation of magnetic anisotropy, K, with magnetisation, M, in metallic ferromagnets. We apply the theory to the high magnetic anisotropy material, L1_0-ordered FePt, and find its uniaxial K consistent with a magnetic easy axis perpendicular to the Fe/Pt layering for all M and to be proportional to M^2 for a broad range of values of M. For small M, near the Curie temperature, the calculations pick out the easy axis for the onset of magnetic order. Our results are in good agreement with recent experimental measurements on this important magnetic material.Comment: 4 pages, 2 figure

A longitudinal study on the occurrence of Cryptosporidium and Giardia in dogs during their first year of life

<p>Abstract</p> <p>Background</p> <p>The primary aim of this study was to obtain more knowledge about the occurrence of <it>Cryptosporidium </it>and <it>Giardia </it>in young dogs in Norway.</p> <p>The occurrence of these parasites was investigated in a longitudinal study by repeated faecal sampling of dogs between 1 and 12 months of age (litter samples and individual samples). The dogs were privately owned and from four large breeds. Individual faecal samples were collected from 290 dogs from 57 litters when the dogs were approximately 3, 4, 6, and 12 months old. In addition, pooled samples were collected from 43 of the litters, and from 42 of the mother bitches, when the puppies were approximately 1 and/or 2 months old.</p> <p>Methods</p> <p>The samples were purified by sucrose gradient flotation concentration and examined by immunofluorescent staining.</p> <p>Results</p> <p>128 (44.1%) of the young dogs had one or more <it>Cryptosporidium </it>positive samples, whilst 60 (20.7%) dogs had one or more <it>Giardia </it>positive samples. The prevalence of the parasites varied with age. For <it>Cryptosporidium</it>, the individual prevalence was between 5.1% and 22.5%, with the highest level in dogs < 6 months old, and declining with age. For <it>Giardia</it>, the individual prevalence was between 6.0% and 11.4%, with the highest level in dogs > 6 months old, but the differences between age groups were not statistically significant. Significant differences in prevalences were found in relation to geographic location of the dogs. Both parasites occurred at low prevalences in Northern Norway.</p> <p>Conclusion</p> <p>Both <it>Cryptosporidium </it>and <it>Giardia </it>are common in Norwegian dogs, with <it>Cryptosporidium </it>more prevalent than <it>Giardia</it>. Prevalences of the parasites were found to be influenced by age, geographical location, and infection status before weaning.</p

Anisotropic nanomaterials: structure, growth, assembly, and functions

Comprehensive knowledge over the shape of nanomaterials is a critical factor in designing devices with desired functions. Due to this reason, systematic efforts have been made to synthesize materials of diverse shape in the nanoscale regime. Anisotropic nanomaterials are a class of materials in which their properties are direction-dependent and more than one structural parameter is needed to describe them. Their unique and fine-tuned physical and chemical properties make them ideal candidates for devising new applications. In addition, the assembly of ordered one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) arrays of anisotropic nanoparticles brings novel properties into the resulting system, which would be entirely different from the properties of individual nanoparticles. This review presents an overview of current research in the area of anisotropic nanomaterials in general and noble metal nanoparticles in particular. We begin with an introduction to the advancements in this area followed by general aspects of the growth of anisotropic nanoparticles. Then we describe several important synthetic protocols for making anisotropic nanomaterials, followed by a summary of their assemblies, and conclude with major applications

Zoonotic potential of Giardia duodenalis and Cryptosporidium spp. and prevalence of intestinal parasites in young dogs from different populations on Prince Edward Island, Canada

The prevalence of Giardia duodenalis, Cryptosporidium spp. and other intestinal parasites was determined in dogs <1 year old from Prince Edward Island, Canada. Fecal samples were collected from the local animal shelter (n=62), private veterinary clinics (n=78) and a pet store (n=69). Intestinal parasites isolated included G. duodenalis, Cryptosporidium spp., Toxocara canis, Isospora spp. and Uncinaria stenocephala. To estimate the zoonotic risk associated with these infections, genotypes of G. duodenalis and Cryptosporidium spp. were determined using 16S rRNA and Hsp70 gene sequencing, respectively. Dogs from the pet store had the highest prevalence of intestinal parasites (78%, 95% CI: 68-88%), followed by the private veterinary clinics (49%, 95% CI: 37-60%), and the local animal shelter (34%, 95% CI: 22-46%). The majority G. duodenalis belonged to host-adapted assemblages D (47%, 95% CI: 31-64%) and C (26%, 95% CI: 13-43%), respectively. Zoonotic assemblages A and B were isolated alone or in mixed infections from 16% (95% CI: 6-31%) of G. duodenalis-positive dogs. All Cryptosporidium spp. were the host-adapted C. canis. While host-adapted, non-zoonotic G. duodenalis genotypes were more common, the presence of G. duodenalis assemblages A and B, T. canis, and U. stenocephala suggests that these dogs may present a zoonotic risk. The zoonotic risk from Cryptosporidium-infected dogs was minimal.Fabienne D. Uehlinger, Spencer J. Greenwood, J. Trenton McClure, Gary Conboy, Ryan O’Handley, Herman W. Barkem

Monensin use against Neospora caninum challenge in dairy cattle

No abstract availableJ.A. VanLeeuwen, S. Greenwood, F. Clark, A. Acorn, F. Markham, J. McCarron, R. O’Handle

Comparison of five diagnostic tests for Giardia duodenalis in fecal samples from young dogs

Five diagnostic tests were compared for the diagnosis of Giardia duodenalis in fecal samples of young dogs. Fecal samples were collected from 136 healthy dogs <1year old and examined using immunofluorescence antibody microscopy (IFA) after sucrose gradient centrifugation, zinc sulfate centrifugal flotation technique (ZSCT), SNAP®Giardia test, and ProSpecT®Giardia EZ Microplate assay. In addition, polymerase chain reaction (PCR) of the 16S rRNA gene was performed. Kappa (κ) statistic was calculated to assess diagnostic agreement between the IFA and each test. Using the IFA as the gold standard, the relative sensitivity and specificity of each test were determined. Subsequently, a Bayesian approach was used to estimate the sensitivity and specificity of each test in comparison to the IFA results. Giardia duodenalis was detected in 41% of the samples examined by IFA. The ZSCT resulted in 37% of positive samples, with a relative sensitivity and specificity of 86 and 98%, respectively. The SNAP®Giardia test was positive in 40% of the samples, with a relative sensitivity and specificity of 91 and 96%, respectively. The ProSpecT® test was positive in 51% of the samples, with a relative sensitivity and specificity of 100 and 83%, respectively. The relative sensitivity and specificity for PCR were 58 and 56%, respectively, with 55% of samples being PCR-positive. While the sensitivity and specificity estimates of each test in comparison to the IFA changed when using a Bayesian approach, the conclusions remained the same. While the ProSpecT® test was the most sensitive test in this study, it is not designed for dogs and more costly than the other tests. The SNAP®Giardia test performed similar to the ZSCT but may be more favorable because it is fast and easy to perform. Performance of the PCR was poor and the benefit of PCR may be in determining genotypes for evaluating zoonotic transfer between dogs and humans.Fabienne D. Uehlinger, S. Ali Naqvi, Spencer J. Greenwood, J. Trenton Clure, Gary Conboy, Ryan O’Handley, Herman W. Barkem

Preparation of C8-amine and acetylamine adducts of 2'-deoxyguanosine suitably protected for DNA synthesis

[reaction: see text] C8-Amine and acetylamine adducts of 2'-deoxyguanosine were synthesized. Our approach provides solutions for the coupling of aromatic amines to a protected 8-bromo-2'-deoxyguanosine derivative, for the selective acetylation of the coupled adduct at N(8) and for a protecting group scheme preserving the integrity of the base-labile N(8) acetyl group during DNA synthesis