Uniaxial strain control of spin-polarization in multicomponent nematic order of BaFe2_{2}As2_{2}

The iron-based high temperature superconductors exhibit a rich phase diagram reflecting a complex interplay between spin, lattice, and orbital degrees of freedom [1-4]. The nematic state observed in many of these compounds epitomizes this complexity, by entangling a real-space anisotropy in the spin fluctuation spectrum with ferro-orbital order and an orthorhombic lattice distortion [5-7]. A more subtle and much less explored facet of the interplay between these degrees of freedom arises from the sizable spin-orbit coupling present in these systems, which translates anisotropies in real space into anisotropies in spin space. Here, we present a new technique enabling nuclear magnetic resonance under precise tunable strain control, which reveals that upon application of a tetragonal symmetry-breaking strain field, the magnetic fluctuation spectrum in the paramagnetic phase of BaFe$_{2}$As$_{2}$ also acquires an anisotropic response in spin-space. Our results unveil a hitherto uncharted internal spin structure of the nematic order parameter, indicating that similar to liquid crystals, electronic nematic materials may offer a novel route to magneto-mechanical control.Comment: 11 pages, 5 figure

Graded-bandgap AlGaAs solar cells for AlGaAs/Ge cascade cells

Some p/n graded-bandgap Al(x)Ga(1-x)As solar cells were fabricated and show AMO conversion efficiencies in excess of 15 percent without antireflection (AR) coatings. The emitters of these cells are graded between 0.008 is less than or equal to x is less than or equal to 0.02 during growth of 0.25 to 0.30 micron thick layers. The keys to achieving this performance were careful selection of organometallic sources and scrubbing oxygen and water vapor from the AsH3 source. Source selection and growth were optimized using time-resolved photoluminescence. Preliminary radiation-resistance measurements show AlGaAs cells degraded less than GaAs cells at high 1 MeV electron fluences, and AlGaAs cells grown on GaAs and Ge substrates degrade comparably

Uniaxial strain control of spin-polarization in multicomponent nematic order of BaFe2As2

The iron-based high temperature superconductors exhibit a rich phase diagram reflecting a complex interplay between spin, lattice, and orbital degrees of freedom. The nematic state observed in these compounds epitomizes this complexity, by entangling a real-space anisotropy in the spin fluctuation spectrum with ferro-orbital order and an orthorhombic lattice distortion. A subtle and less-explored facet of the interplay between these degrees of freedom arises from the sizable spin-orbit coupling present in these systems, which translates anisotropies in real space into anisotropies in spin space. We present nuclear magnetic resonance studies, which reveal that the magnetic fluctuation spectrum in the paramagnetic phase of BaFe2As2 acquires an anisotropic response in spin-space upon application of a tetragonal symmetry-breaking strain field. Our results unveil an internal spin structure of the nematic order parameter, indicating that electronic nematic materials may offer a route to magneto-mechanical control

No effect of glutamine supplementation and hyperoxia on oxidative metabolism and performance during high-intensity exercise.

addresses: Health and Biology, Liverpool Hope University, Liverpool, UK. [email protected]: Comparative Study; Journal ArticleThis is an Author's Accepted Manuscript of an article published in Journal of Sports Sciences, 2008, Vol. 26, Issue 10, pp. 1081 – 1090 © 2008 copyright Taylor & Francis, available online at: http://www.tandfonline.com/doi/abs/10.1080/02640410801930200Glutamine enhances the exercise-induced expansion of the tricarboxylic acid intermediate pool. The aim of the present study was to determine whether oral glutamine, alone or in combination with hyperoxia, influenced oxidative metabolism and cycle time-trial performance. Eight participants consumed either placebo or 0.125 g kg body mass(-1) of glutamine in 5 ml kg body mass(-1) placebo 1 h before exercise in normoxic (control and glutamine respectively) or hyperoxic (FiO(2) = 50%; hyperoxia and hyperoxia + glutamine respectively) conditions. Participants then cycled for 6 min at 70% maximal oxygen uptake (VO(2max)) immediately before completing a brief high-intensity time-trial (approximately 4 min) during which a pre-determined volume of work was completed as fast as possible. The increment in pulmonary oxygen uptake during the performance test (DeltaVO(2max), P = 0.02) and exercise performance (control: 243 s, s(x) = 7; glutamine: 242 s, s(x) = 3; hyperoxia: 231 s, s(x) = 3; hyperoxia + glutamine: 228 s, s(x) = 5; P < 0.01) were significantly improved in hyperoxic conditions. There was some evidence that glutamine ingestion increased DeltaVO(2max) in normoxia, but not hyperoxia (interaction drink/FiO(2), P = 0.04), but there was no main effect or impact on performance. Overall, the data show no effect of glutamine ingestion either alone or in combination with hyperoxia, and thus no limiting effect of the tricarboxylic acid intermediate pool size, on oxidative metabolism and performance during maximal exercise

NMR study of nematic spin fluctuations in a detwinned single crystal of underdoped Ba(Fe1−xCox)2As2

We report the experimental details of how mechanical detwinning can be implemented in tandem with high-sensitivity nuclear magnetic resonance measurements and use this setup to measure the in-plane anisotropy of the spin-lattice relaxation rate in underdoped Ba(Fe1−xCox )2As2 with x = 0.048. The anisotropy reaches a maximum of 30% at TN, and the recovery data reveal that the glassy behavior of the spin fluctuations present in the twinned state persist in the fully detwinned crystal. A theoretical model is presented to describe the spin-lattice relaxation rate in terms of anisotropic nematic spin fluctuations

A quantitative approach for measuring the reservoir of latent HIV-1 proviruses.

A stable latent reservoir for HIV-1 in resting CD4+ T cells is the principal barrier to a cure1-3. Curative strategies that target the reservoir are being tested4,5 and require accurate, scalable reservoir assays. The reservoir was defined with quantitative viral outgrowth assays for cells that release infectious virus after one round of T cell activation1. However, these quantitative outgrowth assays and newer assays for cells that produce viral RNA after activation6 may underestimate the reservoir size because one round of activation does not induce all proviruses7. Many studies rely on simple assays based on polymerase chain reaction to detect proviral DNA regardless of transcriptional status, but the clinical relevance of these assays is unclear, as the vast majority of proviruses are defective7-9. Here we describe a more accurate method of measuring the HIV-1 reservoir that separately quantifies intact and defective proviruses. We show that the dynamics of cells that carry intact and defective proviruses are different in vitro and in vivo. These findings have implications for targeting the intact proviruses that are a barrier to curing HIV infection

Actual and ideal roles of school staff to support students with special needs: Current needs and strategies for improvement

To optimise school-based service delivery for students with disabilities, it is important to understand roles and needs of school staff. This study aimed to clarify ideal and actual roles of school staff (teachers, special educators, administrators) working with students with special needs, and to identify potential strategies to support actual roles. Ninety-five school personnel (64% teachers) from 3 different elementary schools and school boards in Quebec completed a 14-question survey. Open-ended responses were coded and analysed thematically. Common actual roles included task adaptation, offering individualized support, being available, and teamwork. Respondents felt roles could improve through in-context professional support, continuing education, teamwork opportunities extending to partnerships with families, and access to resources. Clarifying roles and expectations within a tiered-model to best support students also emerged, emphasizing the importance of sharing responsibilities across all service providers. Findings can guide implementation strategies and processes for providing effective services, enabling inclusion for students

Fate specification and tissue-specific cell cycle control of the <i>Caenorhabditis elegans</i> intestine

Coordination between cell fate specification and cell cycle control in multicellular organisms is essential to regulate cell numbers in tissues and organs during development, and its failure may lead to oncogenesis. In mammalian cells, as part of a general cell cycle checkpoint mechanism, the F-box protein β-transducin repeat-containing protein (β-TrCP) and the Skp1/Cul1/F-box complex control the periodic cell cycle fluctuations in abundance of the CDC25A and B phosphatases. Here, we find that the Caenorhabditis elegans β-TrCP orthologue LIN-23 regulates a progressive decline of CDC-25.1 abundance over several embryonic cell cycles and specifies cell number of one tissue, the embryonic intestine. The negative regulation of CDC-25.1 abundance by LIN-23 may be developmentally controlled because CDC-25.1 accumulates over time within the developing germline, where LIN-23 is also present. Concurrent with the destabilization of CDC-25.1, LIN-23 displays a spatially dynamic behavior in the embryo, periodically entering a nuclear compartment where CDC-25.1 is abundant