Magnetic force microscopy characterization of a first-order transition: Magnetic-martensitic phase transformation in Gd5(SixGe1−x)4

The magnetic-martensitic phase transformation of Gd5(SixGe1−x)4 (x≈0.5), which occurs close to room temperature, has been observed for the first time using a magnetic force microscope (MFM) equipped with a heating–cooling stage. MFM images obtained from a polycrystalline Gd5(Si2.09Ge1.91) sample and single crystal Gd5(Si1.95Ge2.05)and Gd5(Si2Ge2) samples showed transition to a domain structure at low temperatures indicative of a ferromagnetic phase. Some samples exhibited complex domain structures,suggesting that Gd5(SixGe1−x)4 (x≈0.5) has a strong magnetic anisotropy. As the sample temperature increased the domain structure diminished, reflecting the transformation from ferromagnetic to paramagnetic state. On cooling the sample the domain structurereappeared, but at a lower transformation temperature than on heating. This magnetic phase transformation is highly unusual because it is an “order–disorder” phase transition, which is normally second order, but in this case the “order–disorder” (ferromagnetic to paramagnetic)transition exhibits hysteresis in temperature, indicating that it is first order. Such thermalhysteresis in phase transformation was also observed in thermal expansion experiments. The transformation temperatures obtained in the MFM study are in good agreement with those determined from thermal expansion data

Cobalt ferrite based magnetostrictive materials for magnetic stress sensor and actuator applications

Magnetostrictive material based on cobalt ferrite is described. The cobalt ferrite is substituted with transition metals (such manganese (Mn), chromium (Cr), zinc (Zn) and copper (Cu) or mixtures thereof) by substituting the transition metals foriron or cobalt to form substituted cobalt ferrite that provides mechanical properties that make the substituted cobalt ferrite material effective for use as sensors andactuators. The substitution of transition metals lowers the Curie temperature of the material (as compared to cobalt ferrite) while maintaining a suitable magnetostriction for stress sensing applications

Inter-rater reliability of cyclic and non-cyclic task assessment using the hand activity level in appliance manufacturing

This study evaluated the inter-rater reliability of the American Conference of Governmental Industrial Hygienists (ACGIH) hand activity level (HAL), an observational ergonomic assessment method used to estimate physical exposure to repetitive exertions during task performance. Video recordings of 858 cyclic and non-cyclic appliance manufacturing tasks were assessed by sixteen pairs of raters using the HAL visual-analog scale. A weighted Pearson Product Moment-Correlation Coefficient was used to evaluate the agreement between the HAL scores recorded by each rater pair, and the mean weighted correlation coefficients for cyclic and non-cyclic tasks were calculated. Results indicated that the HAL is a reliable exposure assessment method for cyclic (r-barw = 0.69) and non-cyclic work tasks (r-barw = 0.68). When the two reliability scores were compared using a two-sample Student’s t-test, no significant difference in reliability (p = 0.63) between these work task categories was found. This study demonstrated that the HAL may be a useful measure of exposure to repetitive exertions during cyclic and non-cyclic tasks. Relevance to industry: Exposure to hazardous levels of repetitive action during non-cyclic task completion has traditionally been difficult to assess using simple observational techniques. The present study suggests that ergonomists could use the HAL to reliably and easily evaluate exposures associated with some non-cyclic work tasks

Left-right dissociation of hippocampal memory processes in mice.

Left-right asymmetries have likely evolved to make optimal use of bilaterian nervous systems; however, little is known about the synaptic and circuit mechanisms that support divergence of function between equivalent structures in each hemisphere. Here we examined whether lateralized hippocampal memory processing is present in mice, where hemispheric asymmetry at the CA3-CA1 pyramidal neuron synapse has recently been demonstrated, with different spine morphology, glutamate receptor content, and synaptic plasticity, depending on whether afferents originate in the left or right CA3. To address this question, we used optogenetics to acutely silence CA3 pyramidal neurons in either the left or right dorsal hippocampus while mice performed hippocampus-dependent memory tasks. We found that unilateral silencing of either the left or right CA3 was sufficient to impair short-term memory. However, a striking asymmetry emerged in long-term memory, wherein only left CA3 silencing impaired performance on an associative spatial long-term memory task, whereas right CA3 silencing had no effect. To explore whether synaptic properties intrinsic to the hippocampus might contribute to this left-right behavioral asymmetry, we investigated the expression of hippocampal long-term potentiation. Following the induction of long-term potentiation by high-frequency electrical stimulation, synapses between CA3 and CA1 pyramidal neurons were strengthened only when presynaptic input originated in the left CA3, confirming an asymmetry in synaptic properties. The dissociation of hippocampal long-term memory function between hemispheres suggests that memory is routed via distinct left-right pathways within the mouse hippocampus, and provides a promising approach to help elucidate the synaptic basis of long-term memory.http://dx.doi.org/10.1073/pnas.1405648111This is the author's accepted manuscript. It will be under embargo for 6 months from the date of publication. The final version is available from PNAS at http://www.pnas.org/content/early/2014/09/16/1405648111.abstract

GONADOTROPHINS AND TESTOSTERONE IN THE XYY SYNDROME

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32715/1/0000082.pd

Composite genome map and recombination parameters derived from three archetypal lineages of Toxoplasma gondii

Toxoplasma gondii is a highly successful protozoan parasite in the phylum Apicomplexa, which contains numerous animal and human pathogens. T.gondii is amenable to cellular, biochemical, molecular and genetic studies, making it a model for the biology of this important group of parasites. To facilitate forward genetic analysis, we have developed a high-resolution genetic linkage map for T.gondii. The genetic map was used to assemble the scaffolds from a 10X shotgun whole genome sequence, thus defining 14 chromosomes with markers spaced at ∼300 kb intervals across the genome. Fourteen chromosomes were identified comprising a total genetic size of ∼592 cM and an average map unit of ∼104 kb/cM. Analysis of the genetic parameters in T.gondii revealed a high frequency of closely adjacent, apparent double crossover events that may represent gene conversions. In addition, we detected large regions of genetic homogeneity among the archetypal clonal lineages, reflecting the relatively few genetic outbreeding events that have occurred since their recent origin. Despite these unusual features, linkage analysis proved to be effective in mapping the loci determining several drug resistances. The resulting genome map provides a framework for analysis of complex traits such as virulence and transmission, and for comparative population genetic studies

Continental-Scale Increase in Lake and Stream Phosphorus: Are Oligotrophic Systems Disappearing in the United States?

This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes.We describe continental-scale increases in lake and stream total phosphorus (TP) concentrations, identified through periodic probability surveys of thousands of water bodies in the conterminous U.S. The increases, observed over the period 2000–2014 were most notable in sites in relatively undisturbed catchments and where TP was initially low (e.g., less than 10 μg L⁻¹). Nationally, the percentage of stream length in the U.S. with TP ≤ 10 μg L⁻¹ decreased from 24.5 to 10.4 to 1.6% from 2004 to 2009 to 2014; the percentage of lakes with TP ≤ 10 μg L⁻¹ decreased from 24.9 to 6.7% between 2007 and 2012. Increasing TP concentrations appear to be ubiquitous, but their presence in undeveloped catchments suggests that they cannot be entirely attributed to either point or common non-point sources of TP

Temperature dependence of magnetic anisotropy in Mn-substituted cobalt ferrite

The temperature variation of magnetic anisotropy and coercive field of magnetoelastic manganese-substituted cobalt ferrites (CoMnxFe2?xO4 with 0 ? x ? 0.6) was investigated. Major magnetic hysteresis loops were measured for each sample at temperatures over the range 10–400 K, using a superconducting quantum interference device magnetometer. The high-field regimes of the hysteresis loops were modeled using the law of approach to saturation equation, based on the assumption that at sufficiently high field only rotational processes remain, with an additional forced magnetization term that was linear with applied field. The cubic anisotropy constant K1 was calculated from the fitting of the data to the theoretical equation. It was found that anisotropy increases substantially with decreasing temperature from 400 to 150 K, and decreases with increasing Mn content. Below 150 K, it appears that even under a maximum applied field of 5 T, the anisotropy of CoFe2O4 and CoMn0.2Fe1.8O4 is so high as to prevent complete approach to saturation, thereby making the use of the law of approach questionable in these cases