Evolution of the magnetic excitations in NaOsO3_3 through its metal-insulator transition

The temperature dependence of the excitation spectrum in NaOsO$_{\text{3}}$ through its metal-to-insulator transition (MIT) at 410 K has been investigated using resonant inelastic X-ray scattering (RIXS) at the Os L$_{\text{3}}$ edge. High resolution ($\Delta E \sim$ 56 meV) measurements show that the well-defined, low energy magnons in the insulating state weaken and dampen upon approaching the metallic state. Concomitantly, a broad continuum of excitations develops which is well described by the magnetic fluctuations of a nearly antiferromagnetic Fermi liquid. By revealing the continuous evolution of the magnetic quasiparticle spectrum as it changes its character from itinerant to localized, our results provide unprecedented insight into the nature of the MIT in NaOsO$_{\text{3}}$.Comment: Accepted in Physical Review Letters, part of a joint submission to Physical Review B. Supersedes arXiv:1707.0555

Statistical properties of near‐surface flow in the California coastal transition zone

The article of record as published may be found at https://doi.org/10.1029/91JC01072During the summers of 1987 and 1988, 77 near-surface satellite-tracked drifters were deployed in or near cold filaments near Point Arena, California (39°N), and tracked for up to 6 months as part of the Coastal Transition Zone (CTZ) program. The drifters had large drogues centered at 15 m, and the resulting drifter trajectory data set has been analyzed in terms of its Eulerian and Lagrangian statistics. The CTZ drifter results show that the California Current can be characterized in summer and fall as a meandering coherent jet which on average flows southward to at least 30°N, the southern end of the study domain. From 39°N south to about 33°N, the typical core velocities are of O(50 cm s−1) and the current meanders have alongshore wavelengths of O (300 km) and onshore-offshore amplitude of O(100–200 km). The lateral movement of this jet leads to large eddy kinetic energies and large eddy diffusivities, especially north of 36°N. The initial onshore-offshore component of diffusivity is always greater than the alongshore component in the study domain, but at the southern end, the eddy diffusivity is more isotropic, with scalar single particle diffusivity (Kxx + Kyy) of O(8 × 107 cm2 s−1). The eddy diffusivity increases with increasing eddy energy. Finally, a simple volume budget for the 1988 filament observed near 37°N off Point Arena suggests that subduction can occur in a filament at an average rate of O (10 m d−1) some 200 km offshore, thus allowing the cold water initially in the filament core to sink below the warmer ambient water by the time the surface velocity core has turned back onshore. This process explains why satellite temperature and color imagery tend to “see” only flow proceeding offshore

Mesoscale Hydrographic Variability in the Vicinity of Points Conception and Arguello During April May 1983: The OPUS 1983 Experiment

In April and May 1983, interdisciplinary oceanographic observations were made of upwelling events in the Point Conception area off southern California. The principal objective was to observe the structure and time dependence of the upwelling system. To accomplish this, two ships, two aircraft, moorings, drogues, and satellite imagery were all included in the observational effort. During the intensive measurement period three main upwelling events and two intervening relaxation or downwelling intervals were sampled during what was a period of overall longer-term sea surface warming. Surface temperatures during upwelling were as low as 10.5°C in the upwelling center between Point Arguello and Point Conception, while during periods of nonupwelling winds, temperatures reached 14°–15°C in the same area. The upwelling center was also a source of higher-salinity water (33.7‰) relative to the offshore waters that were anomalously fresh (33.3‰). Upwelling was observed off Point Arguello, Point Conception, and the area between with a possible lag of up to a day at Point Conception relative to the other areas. The upwelling plume as observed by surface mapping and remote sensing tended to move in a variety of directions from SE to SW. Part of the movement was usually into the Santa Barbara Channel, but other parts of the plume occasionally moved southwestward. There was no obvious correlation of plume direction with the wind. During relaxation events the entire region was covered by a 10- to 20-m-thick warm (14°–16°C), fresh

BAFF selectively enhances the survival of plasmablasts generated from human memory B cells

The generation of Ig-secreting cells (ISCs) from memory B cells requires interactions between antigen-specific (Ag-specific) B cells, T cells, and dendritic cells. This process must be strictly regulated to ensure sufficient humoral immunity while avoiding production of pathogenic autoantibodies. BAFF, a member of the TNF family, is a key regulator of B cell homeostasis. BAFF exerts its effect by binding to three receptors — transmembrane activator of and CAML interactor (TACI), B cell maturation antigen (BCMA), and BAFF receptor (BAFF-R). To elucidate the contribution of BAFF to the differentiation of B cells into ISCs, we tracked the fate of human memory B cells stimulated with BAFF or CD40L. BAFF and CD40L significantly increased the overall number of surviving B cells. This was achieved via distinct mechanisms. CD40L induced proliferation of nondifferentiated blasts, while BAFF prevented apoptosis of ISCs without enhancing proliferation. The altered responsiveness of activated memory B cells to CD40L and BAFF correlated with changes in surface phenotype such that expression of CD40 and BAFF-R were reduced on ISCs while BCMA was induced. These results suggest BAFF may enhance humoral immunity in vivo by promoting survival of ISCs via a BCMA-dependent mechanism. These findings have wide-ranging implications for the treatment of human immunodeficiencies as well as autoimmune diseases.This work was supported by the National Health and Medical Research Council of Australia. S.G. Tangye was supported by a U2000 Postdoctoral Fellowship awarded by the University of Sydney. P.D. Hodgkin is a Senior Research Fellow of the National Health and Medical Research Council of Australia. F. Mackay is a Wellcome Trust Senior Research Fellow

Indicators for Assessing Habitat Values and Pressures for Protected Areas—An Integrated Habitat and Land Cover Change Approach for the Udzungwa Mountains National Park in Tanzania

Assessing the status and monitoring the trends of land cover dynamics in and around protected areas is of utmost importance for park managers and decision makers. Moreover, to support the Convention on Biological Diversity (CBD)’s Strategic Action Plan including the Aichi Biodiversity Targets, such efforts are necessary to set a framework to reach the agreed national, regional or global targets. The integration of land use/cover change (LULCC) data with information on habitats and population density provides the means to assess potential degradation and disturbance resulting from anthropogenic activities such as agriculture and urban area expansion. This study assesses the LULCC over a 20 year (1990–2000–2010) period using freely available Landsat imagery and a dedicated method and toolbox for the Udzungwa Mountains National Park (UMNP) and its surroundings (20 km buffer) in Tanzania. Habitat data gathered from the Digital Observatory for Protected Areas (DOPA)’s eHabitat+ Web service were used to perform ecological stratification of the study area and to develop similarity maps of the potential presence of comparable habitat types outside the protected area. Finally, integration of the habitat similarity maps with the LULCC data was applied in order to evaluate potential pressures on the different habitats within the national park and on the linking corridors between UMNP and other protected areas in the context of wildlife movement and migration. The results show that the UMNP has not suffered from relevant human activities during the study period. The natural vegetation area has remained stable around 1780 km2. In the surrounding 20 km buffer area and the connecting corridors, however, the anthropogenic impact has been strong. Artificially built up areas increased by 14.24% over the last 20 years and the agriculture area increased from 11% in 1990 to 30% in the year 2010. The habitat functional types and the similarity maps confirmed the importance of the buffer zone and the connecting corridors for wildlife movements, while the similarity maps detected other potential corridors for wildlife

Attitude toward contraception and abortion among Curaçao women. Ineffective contraception due to limited sexual education?

Background In Curaçao is a high incidence of unintended pregnancies and induced abortions. Most of the induced abortions in Curaçao are on request of the woman and performed by general practitioners. In Curaçao, induced abortion is strictly prohibited, but since 1999 there has been a policy of connivance. We present data on the relevance of economic and socio-cultural factors for the high abortion-rates and the ineffective use of contraception. Methods Structured interviews to investigate knowledge and attitudes toward sexuality, contraception and abortion and reasons for ineffective use of contraceptives among women, visiting general practitioners. Results Of 158 women, 146 (92%) participated and 82% reported that their education on sexuality and about contraception was of good quality. However 'knowledge of reliable contraceptive methods' appeared to be - in almost 50% of the cases - false information, misjudgements or erroneous views on the chance of getting pregnant using coitus interruptus and about the reliability and health effects of oral contraceptive pills. Almost half of the interviewed women had incorrect or no knowledge about reliability of condom use and IUD. 42% of the respondents risked by their behavior an unplanned pregnancy. Most respondents considered abortion as an emergency procedure, not as contraception. Almost two third experienced emotional, physical or social problems after the abortion. Conclusions Respondents had a negative attitude toward reliable contraceptives due to socio-cultural determined ideas about health consequences and limited sexual education. Main economic factors were costs of contraceptive methods, because most health insurances in Curaçao do not cover contraceptives. To improve the effective use of reliable contraceptives, more adequate information should be given, targeting the wrong beliefs and false information. The government should encourage health insurance companies to reimburse contraceptives. Furthermore, improvement of counseling during the abortion procedure is important

T Follicular Helper Cells Have Distinct Modes of Migration and Molecular Signatures in Naive and Memory Immune Responses

SummaryB helper follicular T (Tfh) cells are critical for long-term humoral immunity. However, it remains unclear how these cells are recruited and contribute to secondary immune responses. Here we show that primary Tfh cells segregate into follicular mantle (FM) and germinal center (GC) subpopulations that display distinct gene expression signatures. Restriction of the primary Tfh cell subpopulation in the GC was mediated by downregulation of chemotactic receptor EBI2. Following collapse of the GC, memory T cells persisted in the outer follicle where they scanned CD169+ subcapsular sinus macrophages. Reactivation and intrafollicular expansion of these follicular memory T cells in the subcapsular region was followed by their extrafollicular dissemination via the lymphatic flow. These data suggest that Tfh cells integrate their antigen-experience history to focus T cell help within the GC during primary responses but act rapidly to provide systemic T cell help after re-exposure to the antigen

On the road to discovery of relic gravitational waves: The TE and BB Correlations in the cosmic microwave background radiation

The detection of primordial gravitational waves is one of the biggest challenges of the present time. The existing (Wilkinson Microwave Anisotropy Probe) observations are helpful on the road to this goal, and the forthcoming experiments (Planck) are likely to complete this mission. We show that the 5-year Wilkinson Microwave Anisotropy Probe $TE$ data contains a hint of the presence of gravitational wave contribution. In terms of the parameter $R$, which gives the ratio of contributions from gravitational waves and density perturbations to the temperature quadrupole, the best-fit model produced $R=0.24$. Because of large residual noises, the uncertainty of this determination is still large, and it easily includes the R=0 hypothesis. However, the uncertainty will be strongly reduced in the forthcoming observations which are more sensitive. We numerically simulated the Planck data and concluded that the relic gravitational waves with $R=0.24$ will be present at a better than 3$\sigma$ level in the $TE$ observational channel, and at a better than 2$\sigma$ level in the `realistic' $BB$ channel. The balloon-borne and ground-based observations may provide a healthy competition to Planck in some parts of the lower-$\ell$ spectrum.Comment: 39 pages, including 23 figures. Modifications and clarifications in response to referees' comments have been added. Includes the final corrections made at proof reading stage. Published in PR

Antibracket, Antifields and Gauge-Theory Quantization

The antibracket formalism for gauge theories, at both the classical and quantum level, is reviewed. Gauge transformations and the associated gauge structure are analyzed in detail. The basic concepts involved in the antibracket formalism are elucidated. Gauge-fixing, quantum effects, and anomalies within the field-antifield formalism are developed. The concepts, issues and constructions are illustrated using eight gauge-theory models.Comment: 191 pages in three files which must be put together, in Latex, to appear in Physics Report