124 research outputs found

    Jahn-Teller Distortion and Ferromagnetism in the Dilute Magnetic Semiconductors GaN:Mn

    Full text link
    Using first-principles total-energy methods, we investigate Jahn-Teller distortions in III-V dilute magnetic semiconductors, GaAs:Mn and GaN:Mn in the cubic zinc blende structure. The results for an isolated Mn impurity on a Ga site show that there is no appreciable effect in GaAs, whereas, in GaN there is a Jahn-Teller effect in which the symmetry around the impurity changes from Td_{d} to D2d_{2d} or to C2v_{2v}. The large effect in GaN occurs because of the localized d4^4 character, which is further enhanced by the distortion. The lower symmetry should be detectable experimentally in cubic GaN with low Mn concentration, and should be affected by charge compensation (reductions of holes and conversion of Mn ions to d5^5 with no Jahn-Teller effect). Jahn-Teller effect is greatly reduced because the symmetry at each Mn site is lowered due to the Mn-Mn interaction. The tendency toward ferromagnetism is found to be stronger in GaN:Mn than in GaAs:Mn and to be only slightly reduced by charge compensation.Comment: 6 pages, 3 figure

    5PMICROTUBULE-DEPOLYMERIZING AGENTS USED IN ANTIBODY-DRUG-CONJUGATES INDUCE ANTITUMOR ACTIVITY BY STIMULATION OF DENDRITIC CELLS

    Get PDF
    Antibody drug conjugates (ADCs) are emerging as powerful treatment strategies with outstanding target specificity and high therapeutic activity in cancer patients. While >30 ADCs are currently being investigated in clinical trials, brentuximabvedotin and T-DM1 represent clinically approved ADCs in cancer patients. We hypothesized that their sustained clinical responses could be related to the stimulation of an antitumor immune response. Indeed, the two microtubule-destabilizing agents Dolastatin 10 and Ansamitocin P3, from which the cytotoxic components of brentuximabvedotin and T-DM1 are derived, may serve as prototypes for a class of agents that induce tumor cell death and convert tumor resident, tolerogenic dendritic cells (DCs) into efficient antigen presenting cells (APCs). The two drugs induced phenotypic and functional maturation of murine splenic as well as human monocyte-derived DCs. In contrast, microtubule-stabilizing agents such as taxanes did not display this feature. In tumor models, both Dolastatin 10 and Ansamitocin P3 efficiently promoted antigen uptake and migration of tumor-resident DCs to tumor-draining lymph nodes, thereby potentiating tumor-specific T cell responses. Underlining the requirement of an intact host immune system for the full therapeutic benefit of these two compounds, their antitumor effect was far less pronounced in mice lacking adaptive immunity or dendritic cells. Combinations with immune checkpoint inhibition (anti-CTLA-4/-PD-1) did further augment antitumor immunity and tumor rejection, which was reflected by reduced Treg numbers and elevated effector function of tumor resident T cells. Ultimately, we were able to demonstrate peripheral immune cell activation and brisk T cell infiltration into tumors in patients previously treated with BrentuximabVedotin. Experiments are currently ongoing to investigate the immunological mode of action of T-DM1 using orthotopic breast cancer models and patients undergoing treatment. Our data reveal a novel mode of action for microtubule-depolymerizing agents and provide a strong rationale for clinical treatment regimens combining these with immune-based therapies. Disclosure: All authors have declared no conflicts of interes

    Predictors of female sexual dysfunction: a systematic review and qualitative analysis through gender inequality paradigms

    Get PDF
    Background Female sexual dysfunction affects 41% of reproductive-age women worldwide, making it a highly prevalent medical issue. Predictors of female sexual dysfunction are multifaceted and vary from country to country. A synthesis of potential risk factors and protective factors may aid healthcare practitioners in identifying populations at risk, in addition to revealing modifiable factors to prevent sexual dysfunction among reproductive-age women. Methods Observational studies which assessed the prevalence and predictors of female sexual dysfunction in reproductive-age women were systematically sought in relevant databases (2000–2014). Significant predictors were extracted from each included publication. A qualitative analysis of predictors was performed with a focus on types of sexual regimes and level of human development. Results One hundred thirty-five studies from 41 countries were included in the systematic review. The types of predictors varied according to the location of the study, the type of sexual regime and the level of gender inequality in that country/region. Consistently significant risk factors of female sexual dysfunction were: poor physical health, poor mental health, stress, abortion, genitourinary problems, female genital mutilation, relationship dissatisfaction, sexual abuse, and being religious. Consistently significant protective factors included: older age at marriage, exercising, daily affection, intimate communication, having a positive body image, and sex education. Some factors however had an unclear effect: age, education, employment, parity, being in a relationship, frequency of sexual intercourse, race, alcohol consumption, smoking and masturbation. Conclusions The sexual and reproductive lives of women are highly impacted by female sexual dysfunction, and a number of biological, psychological and social factors play a role in the prevalence of sexual dysfunction. Healthcare professionals who work with women should be aware of the many risk factors for reproductive-age women. Future prevention strategies should aim to address modifiable factors, e.g. physical activity and access to sex education; international efforts in empowering women should continue

    Moving Complementary Feeding Forward: Report on a Workshop of the Federation of International Societies for Pediatric Gastroenterology, Hepatology and Nutrition (FISPGHAN) and the World Health Organization Regional Office for Europe.

    Get PDF
    The WHO Regional Office for Europe and the Federation of International Societies for Pediatric Gastroenterology, Hepatology, and Nutrition held a joint workshop, "Moving Complementary Feeding Forward" at the sixth World Congress Pediatric Gastroenterology, Hepatology, and Nutrition in 2021. Here we summarize workshop presentations and discussions. The workshop covered health implications of complementary feeding (CF) including allergies, challenges to meet dietary needs during the CF period, quality of commercial complementary foods (CFD) and respective marketing practices, national CF guidelines in Europe, a nutrient profiling system for CFD, and global policy perspectives on the standards and regulation of marketing for CFD. Adequate CF practices are of critical importance for short and long-term child health, prevention of nutrient deficiencies, normal growth and development, and reducing the risk of allergies. The workshop identified the need to improve feeding practices, harmonize evidence-based information and develop guidance jointly with various stakeholders, improve the composition and marketing practices of commercial CFD and their transparent labeling based on nutrient profiling. Renewed efforts for collaboration between scientists, public health experts, pediatric associations, national governments, and the WHO are necessary for advancing progress

    Thermal diffusivity, effusivity and conductivity of CdMnTe mixed crystals

    Get PDF
    Cd1-xMnxTe mixed crystals belong to a class of materials called ‘‘semimagnetic semiconductor’’ or diluted magnetic semiconductor (DMS) with addition of magnetic ions like Mn2+ implemented into crystal structure. The crystals under investigation were grown from the melt by the high pressure high temperature modified Bridgman method in the range of composition 0 < x < 0.7. Thermal properties of these compounds have been investigated by means of photopyroelectric (PPE) calorimetry in both, back and front detection configuration. The values of the thermal diffusivity and effusivity were derived from experimental data. Thermal conductivity of the specimens was calculated from the simple theoretical dependencies between thermal parameters. The influence of Mn concentration on thermal properties of Cd1-xMnxTe crystals have been presented and discussed

    The Earth System Prediction Suite: Toward a Coordinated U.S. Modeling Capability

    Get PDF
    The Earth System Prediction Suite (ESPS) is a collection of flagship U.S. weather and climate models and model components that are being instrumented to conform to interoperability conventions, documented to follow metadata standards, and made available either under open source terms or to credentialed users.The ESPS represents a culmination of efforts to create a common Earth system model architecture, and the advent of increasingly coordinated model development activities in the U.S. ESPS component interfaces are based on the Earth System Modeling Framework (ESMF), community-developed software for building and coupling models, and the National Unified Operational Prediction Capability (NUOPC) Layer, a set of ESMF-based component templates and interoperability conventions. This shared infrastructure simplifies the process of model coupling by guaranteeing that components conform to a set of technical and semantic behaviors. The ESPS encourages distributed, multi-agency development of coupled modeling systems, controlled experimentation and testing, and exploration of novel model configurations, such as those motivated by research involving managed and interactive ensembles. ESPS codes include the Navy Global Environmental Model (NavGEM), HYbrid Coordinate Ocean Model (HYCOM), and Coupled Ocean Atmosphere Mesoscale Prediction System (COAMPS); the NOAA Environmental Modeling System (NEMS) and the Modular Ocean Model (MOM); the Community Earth System Model (CESM); and the NASA ModelE climate model and GEOS-5 atmospheric general circulation model

    First-principles quantum transport modeling of spin-transfer and spin-orbit torques in magnetic multilayers

    Full text link
    We review a unified approach for computing: (i) spin-transfer torque in magnetic trilayers like spin-valves and magnetic tunnel junction, where injected charge current flows perpendicularly to interfaces; and (ii) spin-orbit torque in magnetic bilayers of the type ferromagnet/spin-orbit-coupled-material, where injected charge current flows parallel to the interface. Our approach requires to construct the torque operator for a given Hamiltonian of the device and the steady-state nonequilibrium density matrix, where the latter is expressed in terms of the nonequilibrium Green's functions and split into three contributions. Tracing these contributions with the torque operator automatically yields field-like and damping-like components of spin-transfer torque or spin-orbit torque vector, which is particularly advantageous for spin-orbit torque where the direction of these components depends on the unknown-in-advance orientation of the current-driven nonequilibrium spin density in the presence of spin-orbit coupling. We provide illustrative examples by computing spin-transfer torque in a one-dimensional toy model of a magnetic tunnel junction and realistic Co/Cu/Co spin-valve, both of which are described by first-principles Hamiltonians obtained from noncollinear density functional theory calculations; as well as spin-orbit torque in a ferromagnetic layer described by a tight-binding Hamiltonian which includes spin-orbit proximity effect within ferromagnetic monolayers assumed to be generated by the adjacent monolayer transition metal dichalcogenide.Comment: 22 pages, 9 figures, PDFLaTeX; prepared for Springer Handbook of Materials Modeling, Volume 2 Applications: Current and Emerging Material

    Utilizing CryoSat-2 sea ice thickness to initialize a coupled ice-ocean modeling system

    Get PDF
    Two CryoSat-2 sea ice thickness products derived with independent algorithms are used to initialize a coupled ice-ocean modeling system in which a series of reanalysis studies are performed for the period of March 15, 2014–September 30, 2015. Comparisons against moored upward looking sonar, drifting ice mass balance buoy, and NASA Operation IceBridge ice thickness data show that the modeling system exhibits greatly reduced bias using the satellite-derived ice thickness data versus the operational model run without these data. The model initialized with CryoSat-2 ice thickness exhibits skill in simulating ice thickness from the initial period to up to 6 months. We find that the largest improvements in ice thickness occur over multi-year ice. Based on the data periods examined here, we find that for the 18-month study period, when compared with upward looking sonar measurements, the CryoSat-2 reanalyses show significant improvement in bias (0.47–0.75) and RMSE (0.89–1.04) versus the control run without these data (1.44 and 1.60, respectively). An ice drift comparison reveals little change in ice velocity statistics for the Pan Arctic region; however some improvement is seen during the summer/autumn months in 2014 for the Bering/Beaufort/Chukchi and Greenland/Norwegian Seas. These promising results suggest that such a technique should be used to reinitialize operational sea ice modeling systems

    The Multi-Scale Infrastructure for Chemistry and Aerosols (MUSICA)

    Get PDF
    To explore the various couplings across space and time and between ecosystems in a consistent manner, atmospheric modeling is moving away from the fractured limited-scale modeling strategy of the past toward a unification of the range of scales inherent in the Earth system. This paper describes the forward-looking Multi-Scale Infrastructure for Chemistry and Aerosols (MUSICA), which is intended to become the next-generation community infrastructure for research involving atmospheric chemistry and aerosols. MUSICA will be developed collaboratively by the National Center for Atmospheric Research (NCAR) and university and government researchers, with the goal of serving the international research and applications communities. The capability of unifying various spatiotemporal scales, coupling to other Earth system components, and process-level modularization will allow advances in both fundamental and applied research in atmospheric composition, air quality, and climate and is also envisioned to become a platform that addresses the needs of policy makers and stakeholders
    • …
    corecore