Lamina-specific AMPA receptor dynamics following visual deprivation in vivo.

Regulation of AMPA receptor (AMPAR) expression is central to synaptic plasticity and brain function, but how these changes occur in vivo remains elusive. Here, we developed a method to longitudinally monitor the expression of synaptic AMPARs across multiple cortical layers in awake mice using two-photon imaging. We observed that baseline AMPAR expression in individual spines is highly dynamic with more dynamics in primary visual cortex (V1) layer 2/3 (L2/3) neurons than V1 L5 neurons. Visual deprivation through binocular enucleation induces a synapse-specific and depth-dependent change of synaptic AMPARs in V1 L2/3 neurons, wherein deep synapses are potentiated more than superficial synapses. The increase is specific to L2/3 neurons and absent on apical dendrites of L5 neurons, and is dependent on expression of the AMPAR-binding protein GRIP1. Our study demonstrates that specific neuronal connections, across cortical layers and even within individual neurons, respond uniquely to changes in sensory experience

Performance of concrete-filled stainless steel tubular (CFSST) columns after exposure to fire

The post-fire performance of concrete-filled stainless steel tubular (CFSST) columns subjected to an entire loading–fire history, including four characteristic phases: (i) ambient temperature loading, (ii) heating, (iii) cooling with constant external loads, and (iv) post-fire loading, is investigated in this paper. Sequentially coupled thermal-stress analyses are performed using ABAQUS to establish the temperature field and structural response of CFSST columns. To improve the precision of the finite element analysis (FEA) models, the influence of moisture on the thermal conductivity and specific heat of the concrete in the heating and cooling phases is considered by using subroutines. Existing fire and post-fire test data on CFSST columns are used to validate the FEA modelling. Comparisons between FEA and test results indicate that the accuracy of the model is acceptable; the FEA model is then extended to simulate CFSST columns subjected to the four characteristic phases. The behaviour of the CFSST columns during the four characteristic phases is explained by analysis of the temperature distribution, load versus axial deformation relations, failure modes and internal force redistribution. The excellent post-fire performance of CFSST columns is examined in comparison with traditional concrete-filled carbon steel tubular (CFST) columns with the same total cross-sectional area. The residual strength index is studied with respect to a series of parametric analyses. It is found that the residual strength of CFSST columns is higher than that of CFST columns after the same fire exposure, and that the diameter of the stainless steel tube, slenderness, heating time ratio and load ratio have a significant influence on the residual strength index

A qualitative study of autism services and supports in Singapore: perspectives of service providers, autistic adults, and caregivers

The lifelong and complex nature of autism necessitates an array of services and supports spanning across different sectors and providers at different life stages of an autistic individual. However, research has shown that autistic individuals and their families often experience barriers accessing the autism-related services and supports that they need. This is the first qualitative study to explore the provision and coordination of autism services and supports in Singapore from the perspectives of service providers, autistic adults and caregivers. Semi-structured interviews with 21 participants revealed three main themes: (1) improving access to autism-specific services, (2) creating flexible supports in an inclusive environment and (3) addressing stigma and changing societal attitudes. Our findings suggest that Singapore may have achieved rapid growth in autism services, but broader social structures may be slower to change. To better support autistic individuals in society, autistic voices need to be amplified and a collective effort is needed to achieve a paradigm shift from impairment to capability

Robust optical emission polarization in MoS2 monolayers through selective valley excitation

We report polarization resolved photoluminescence from monolayer MoS2, a two-dimensional, non-centrosymmetric crystal with direct energy gaps at two different valleys in momentum space. The inherent chiral optical selectivity allows exciting one of these valleys and close to 90% polarized emission at 4K is observed with 40% polarization remaining at 300K. The high polarization degree of the emission remains unchanged in transverse magnetic fields up to 9T indicating robust, selective valley excitation.Comment: 5 pages, 3 figure

Semi-classical States in Homogeneous Loop Quantum Cosmology

Semi-classical states in homogeneous loop quantum cosmology (LQC) are constructed by two different ways. In the first approach, we firstly construct an exponentiated annihilation operator. Then a kind of semi-classical (coherent) state is obtained by solving the eigen-equation of that operator. Moreover, we use these coherent states to analyze the semi-classical limit of the quantum dynamics. It turns out that the Hamiltonian constraint operator employed currently in homogeneous LQC has correct classical limit with respect to the coherent states. In the second approach, the other kind of semi-classical state is derived from the mathematical construction of coherent states for compact Lie groups due to Hall.Comment: 13 pages, submitted to CQ

The mental health status of ethnocultural minorities in Ontario and their mental health care.

Background: Mental disorders are a leading cause of disability and early mortality. The objective of this study was to describe and compare psychosocial indicators and mental health service use among ethnoculturally diverse Ontarians. Methods: This is a cross-sectional analysis of the Ontario Health Study pilot investigation. Residents were mailed an invitation to one of 3 assessment centres (urban, rural and northern sites) from March 2009 to July 2010. Participants had an interview with a nurse and completed a questionnaire on a touchscreen kiosk. The questionnaire included sociodemographic items, and scales assessing symptoms of depressive symptoms (CES-D) and anxiety (GAD-7), social support (Lubben Social Network Scale), stressful life events, and mental health service use. Results: Eight thousand two hundred thirty-five residents participated, among whom 6652 (82.4 %) self-reported their ethnocultural background as White, 225 (2.8 %) as South Asian, 222 (2.8 %) East Asian, 214 (2.7 %) Southeast Asian, 197 (2.4 %) Black, and 28 (0.3 %) as Aboriginal. Based on their sociodemographic characteristics, participants from these ethnocultural minority groups were matched to White participants. Black participants reported significantly greater stressful life events than White participants (p = .04), particularly death (p < .05), divorce (p = .002) and financial difficulties (p < .001). East Asian participants reported significantly less social support than their White counterparts (p < .001), and this was not confounded by measurement variance. Mental health service use was significantly lower in all ethnocultural minorities except Aboriginals, when compared to White participants (p = .001). Conclusions: There is a high burden of psychosocial distress in several preponderant ethnocultural minorities in Ontario; many of whom are not accessing available mental health services

Evaluation of ecotoxicity of typical surfactants for leather manufacture by luminescent bacteria

Content: Surfactants are used as auxiliaries in every wet processing process of leather production and discharged into wastewater, which would cause potential ecological risks. In this paper, fresh luminescent bacillus liquids were employed to evaluate the ecological toxicity of six surfactants, including anionic, cationic and non-ionic surfactants, and mixture of two typical ionic and nonionic surfactants after a 15-min exposure period. Non-ionic surfactants AEO and Tween80 showed slight light inhibition ie.10-35% to luminescent bacteria. The toxicity of anionic surfactants with polar sulfonic group was: penetrant T(EC50=406.81mg/L) ＞SDBS(EC50=573.37mg/L). The toxicity of cationic surfactants was: DTAB（EC50=10.68mg/L）＞SKC （EC50=73.96mg/L）. The addition of nonionic surfactants reduced the toxicity of ionic surfactants. 1-1 mixture of SKC and AEO: EC50=80.17mg/L, 1-1 mixture of SDBS and AEO: EC50=624.34mg/L. These results provided ecological parameters for the selection of surfactants in the process of ecological leather production. Take-Away: 1. The toxicity measurement by luminescent bacteria, which is simple and convenient, was used to evaluate the toxicity of surfactants, and the reproducibility was improved in our study. 2. The toxicities of six different surfactants was evaluated by EC50 which provided ecological parameters for the selection of surfactants in the process of ecological leather production

Osteology of the alvarezsauroid Linhenykus monodactylus from the Upper Cretaceous Wulansuhai Formation of Inner Mongolia, China, and comments on alvarezsauroid biogeography

published_or_final_versio

Naturallyoccurring differences in cenh3 affect chromosome segregation in zygotic mitosis of hybrids

The point of attachment of spindle microtubules to metaphase chromosomes is known as the centromere. Plant and animal centromeres are epigenetically specified by a centromere-specific variant of Histone H3, CENH3 (a.k.a. CENP-A). Unlike canonical histones that are invariant, CENH3 proteins are accumulating substitutions at an accelerated rate. This diversification of CENH3 is a conundrum since its role as the key determinant of centromere identity remains a constant across species. Here, we ask whether naturally occurring divergence in CENH3 has functional consequences. We performed functional complementation assays on cenh3-1, a null mutation in Arabidopsis thaliana, using untagged CENH3s from increasingly distant relatives. Contrary to previous results using GFP-tagged CENH3, we find that the essential functions of CENH3 are conserved across a broad evolutionary landscape. CENH3 from a species as distant as the monocot Zea mays can functionally replace A. thaliana CENH3. Plants expressing variant CENH3s that are fertile when selfed show dramatic segregation errors when crossed to a wild-type individual. The progeny of this cross include hybrid diploids, aneuploids with novel genetic rearrangements and haploids that inherit only the genome of the wild-type parent. Importantly, it is always chromosomes from the plant expressing the divergent CENH3 that missegregate. Using chimeras, we show that it is divergence in the fast-evolving N-terminal tail of CENH3 that is causing segregation errors and genome elimination. Furthermore, we analyzed N-terminal tail sequences from plant CENH3s and discovered a modular pattern of sequence conservation. From this we hypothesize that while the essential functions of CENH3 are largely conserved, the N-terminal tail is evolving to adapt to lineage-specific centromeric constraints. Our results demonstrate that this lineage-specific evolution of CENH3 causes inviability and sterility of progeny in crosses, at the same time producing karyotypic variation. Thus, CENH3 evolution can contribute to postzygotic reproductive barriers

Temperature and Electron Density Dependence of Spin Relaxation in GaAs/AlGaAs Quantum Well

Temperature and carrier density dependent spin dynamics for GaAs/AlGaAs quantum wells (QWs) with different structural symmetry has been studied by using time-resolved Kerr rotation technique. The spin relaxation time is measured to be much longer for the symmetrically-designed GaAs quantum well comparing with the asymmetrical one, indicating the strong influence of Rashba spin-orbit coupling on spin relaxation. D'yakonov-Perel' (DP) mechanism has been revealed to be the dominant contribution for spin relaxation in GaAs/AlGaAs QWs. The spin relaxation time exhibits non-monotonic dependent behavior on both temperature and photo-excited carrier density, revealing the important role of non-monotonic temperature and density dependence of electron-electron Coulomb scattering. Our experimental observations demonstrate good agreement with recently developed spin relaxation theory based on microscopic kinetic spin Bloch equation approach.Comment: 17 pages, 4 figure