Charge dynamics in the half-metallic ferromagnet CrO\u3csub\u3e2\u3c/sub\u3e

Infrared spectroscopy is used to investigate the electronic structure and charge carrier relaxation in crystalline films of CrO2 which is the simplest of all half-metallic ferromagnets. Chromium dioxide is a bad metal at room temperature but it has a remarkably low residual resistivity (\u3c5 \u3eμΩ cm) despite the small spectral weight associated with free carrier absorption. The infrared measurements show that low residual resistivity is due to the collapse of the scattering rate at ω\u3c2000 \u3ecm-1. The blocking of the relaxation channels at low v and T can be attributed to the unique electronic structure of a half-metallic ferromagnet. In contrast to other ferromagnetic oxides, the intraband spectral weight is constant below the Curie temperature

A chromatin modifying enzyme, SDG8, is involved in morphological, gene expression, and epigenetic responses to mechanical stimulation

Thigmomorphogenesis is viewed as being a response process of acclimation to short repetitive bursts of mechanical stimulation or touch. The underlying molecular mechanisms that coordinate changes in how touch signals lead to long-term morphological changes are enigmatic. Touch responsive gene expression is rapid and transient, and no transcription factor or DNA regulatory motif has been reported that could confer a genome wide mechanical stimulus. We report here on a chromatin modifying enzyme, SDG8/ASHH2, which can regulate the expression of many touch responsive genes identified in Arabidopsis. SDG8 is required for the permissive expression of touch induced genes; and the loss of function of sdg8 perturbs the maximum levels of induction on selected touch gene targets. SDG8 is required to maintain permissive H3K4 trimethylation marks surrounding the Arabidopsis touch-inducible gene TOUCH 3 (TCH3), which encodes a calmodulin-like protein (CML12). The gene neighboring was also slightly down regulated, revealing a new target for SDG8 mediated chromatin modification. Finally, sdg8 mutants show perturbed morphological response to wind-agitated mechanical stimuli, implicating an epigenetic memory-forming process in the acclimation response of thigmomorphogenesis

The outcome of extubation failure in a community hospital intensive care unit: a cohort study

INTRODUCTION: Extubation failure has been associated with poor intensive care unit (ICU) and hospital outcomes in tertiary care medical centers. Given the large proportion of critical care delivered in the community setting, our purpose was to determine the impact of extubation failure on patient outcomes in a community hospital ICU. METHODS: A retrospective cohort study was performed using data gathered in a 16-bed medical/surgical ICU in a community hospital. During 30 months, all patients with acute respiratory failure admitted to the ICU were included in the source population if they were mechanically ventilated by endotracheal tube for more than 12 hours. Extubation failure was defined as reinstitution of mechanical ventilation within 72 hours (n = 60), and the control cohort included patients who were successfully extubated at 72 hours (n = 93). RESULTS: The primary outcome was total ICU length of stay after the initial extubation. Secondary outcomes were total hospital length of stay after the initial extubation, ICU mortality, hospital mortality, and total hospital cost. Patient groups were similar in terms of age, sex, and severity of illness, as assessed using admission Acute Physiology and Chronic Health Evaluation II score (P > 0.05). Both ICU (1.0 versus 10 days; P < 0.01) and hospital length of stay (6.0 versus 17 days; P < 0.01) after initial extubation were significantly longer in reintubated patients. ICU mortality was significantly higher in patients who failed extubation (odds ratio = 12.2, 95% confidence interval [CI] = 1.5–101; P < 0.05), but there was no significant difference in hospital mortality (odds ratio = 2.1, 95% CI = 0.8–5.4; P < 0.15). Total hospital costs (estimated from direct and indirect charges) were significantly increased by a mean of US$33,926 (95$22,573–45,280; P < 0.01). CONCLUSION: Extubation failure in a community hospital is univariately associated with prolonged inpatient care and significantly increased cost. Corroborating data from tertiary care centers, these adverse outcomes highlight the importance of accurate predictors of extubation outcome

The near-infrared excitation of the HH211 protostellar outflow

The protostellar outflow HH211 is of considerable interest since it is extremely young and highly collimated. Here, we explore the outflow through imaging and spectroscopy in the near-infrared to determine if there are further diagnostic signatures of youth. We confirm the detection of a near-infrared continuum of unknown origin. We propose that it is emitted by the driving millimeter source, escapes the core through tunnels, and illuminates features aligning the outflow. Narrow-band flux measurements of these features contain an unusually large amount of continuum emission. [Fe II] emission has been detected and is restricted to isolated condensations. However, the characteristics of vibrational excitation of molecular hydrogen resemble those of older molecular outflows. We attempt to model the ordered structure of the western outflow as a series of shocks, finding that bow shocks with J-type dissociative apices and C-type flanks are consistent. Moreover, essentially the same conditions are predicted for all three bows except for a systematic reduction in speed and density with distance from the driving source. We find increased K-band extinctions in the bright regions as high as 2.9 magnitudes and suggest that the bow shocks become visible where the outflow impacts on dense clumps of cloud material. We propose that the outflow is carved out by episodes of pulsating jets. The jets, driven by central explosive events, are responsible for excavating a central tunnel through which radiation temporarily penetrates.Comment: 12 pages, 9 figure

Physiological Response and Tissue Damage Following Different Depths of Impact in a Rodent Model of Mild Traumatic Brain Injury

Mild traumatic brain injury (mTBI) is a serious public health concern that can result in significant neurological and behavioral deficit. mTBI results from impact to the head and can be repetitive in nature, especially in sports and domestic violence cases. Our laboratory studies the effects of repetitive mTBI on risky choice behavior in rodents using a closed-head controlled cortical impact (CH-CCI) model of injury and a well-established probabilistic discounting task that assesses risk-based decision-making behavior. We have recently found that females, but not males, display transient increases in risky choice behavior following three CH-CI’s delivered at 5.5m/s velocity and 2.5 mm impact depth. These findings suggest that our injury parameters may produce marginally threshold influences on behavioral outcomes that do not allow observation of the extent of repetitive mTBI-induced effects and have prompted us to explore expansion of our model to include greater depths of injury. In the present work we subjected rats to a series of three fixed velocity impacts at depths of 2.5mm, 3.0mm, or 3.5mm. The goal was to compare physical manifestations of injury in male and female rats following different depths of injury. The survival rate, righting reflex time, skull injury observations, animal weights, and histological markers of tissue damage were evaluated post-injury. Our hypothesis was that these indices of injury would be more prominent as injury depth increased

CD4+CD25+ T Cells Regulate Virus-specific Primary and Memory CD8+ T Cell Responses

Naturally occurring CD4+CD25+ regulatory T cells appear important to prevent activation of autoreactive T cells. This article demonstrates that the magnitude of a CD8+ T cell–mediated immune response to an acute viral infection is also subject to control by CD4+CD25+ T regulatory cells (Treg). Accordingly, if natural Treg were depleted with specific anti-CD25 antibody before infection with HSV, the resultant CD8+ T cell response to the immunodominant peptide SSIEFARL was significantly enhanced. This was shown by several in vitro measures of CD8+ T cell reactivity and by assays that directly determine CD8+ T cell function, such as proliferation and cytotoxicity in vivo. The enhanced responsiveness in CD25-depleted animals was between three- and fourfold with the effect evident both in the acute and memory phases of the immune response. Surprisingly, HSV infection resulted in enhanced Treg function with such cells able to suppress CD8+ T cell responses to both viral and unrelated antigens. Our results are discussed both in term of how viral infection might temporarily diminish immunity to other infectious agents and their application to vaccines. Thus, controlling suppressor effects at the time of vaccination could result in more effective immunity

The Space Density of Extended Ultraviolet (XUV) Disks in the Local Universe and Implications for Gas Accretion on to Galaxies

We present results of the first unbiased search for extended UV (XUV)-disk galaxies undertaken to determine the space density of such galaxies. Our sample contains 561 local (0.001 < z < 0.05) galaxies that lie in the intersection of available GALEX deep imaging (exposure time > 1.5 x 10^4 s) and SDSS DR7 footprints. We explore modifications to the standard classification scheme for our sample that includes both disk- and bulge-dominated galaxies. Visual classification of each galaxy in the sample reveals an XUV-disk frequency of up to 20% for the most nearby portion of our sample. On average over the entire sample (out to z=0.05) the frequency ranges from a hard limit of 4% to 14%. The GALEX imaging allows us to detect XUV-disks beyond 100 Mpc. The XUV regions around XUV-disk galaxies are consistently bluer than the main bodies. We find a surprisingly high frequency of XUV emission around luminous red (NUV-r > 5) and green valley (3 < NUV-r < 5) galaxies. The XUV-disk space density in the local universe is > 1.5-4.2 x 10^-3 Mpc^-3. Using the XUV emission as an indicator of recent gas accretion, we estimate that the cold gas accretion rate onto these galaxies is > 1.7-4.6 x 10^-3 Msun Mpc^-3 yr^-1. The number of XUV-disks in the green valley and the estimated accretion rate onto such galaxies points to the intriguing possibility that 7%-18% of galaxies in this population are transitioning away from the red sequence.Comment: 19 pages, 24 figures, ApJ in Pres

Disparate Independent Genetic Events Disrupt the Secondary Metabolism Gene \u3cem\u3eperA\u3c/em\u3e in Certain Symbiotic \u3cem\u3eEpichloë\u3c/em\u3e Species

Peramine is an insect-feeding deterrent produced by Epichloë species in symbiotic association with C3 grasses. The perA gene responsible for peramine synthesis encodes a two-module nonribosomal peptide synthetase. Alleles of perA are found in most Epichloë species; however, peramine is not produced by many perA-containing Epichloë isolates. The genetic basis of these peramine-negative chemotypes is often unknown. Using PCR and DNA sequencing, we analyzed the perA genes from 72 Epichloë isolates and identified causative mutations of perA null alleles. We found nonfunctional perA-ΔR* alleles, which contain a transposon-associated deletion of the perA region encoding the C-terminal reductase domain, are widespread within the Epichloë genus and represent a prevalent mutation found in nonhybrid species. Disparate phylogenies of adjacent A2 and T2 domains indicated that the deletion of the reductase domain (R*) likely occurred once and early in the evolution of the genus, and subsequently there have been several recombinations between those domains. A number of novel point, deletion, and insertion mutations responsible for abolishing peramine production in full-length perA alleles were also identified. The regions encoding the first and second adenylation domains (A1 and A2, respectively) were common sites for such mutations. Using this information, a method was developed to predict peramine chemotypes by combining PCR product size polymorphism analysis with sequencing of the perA adenylation domains