Redshifted emission lines and radiative recombination continuum from the Wolf-Rayet binary theta Muscae: evidence for a triplet system?

We present XMM-Newton observations of the WC binary Theta Muscae (WR 48), the second brightest Wolf-Rayet binary in optical wavelengths. The system consists of a short-period (19.1375 days) WC5/WC6 + O6/O7V binary and possibly has an additional O supergiant companion (O9.5/B0Iab) which is optically identified at a separation of ~46 mas. Strong emission lines from highly ionized ions of C, O, Ne, Mg, Si, S, Ar, Ca and Fe are detected. The spectra are fitted by a multi-temperature thin-thermal plasma model with an interstellar absorption N_H = 2--3*10**21 cm**-2. Lack of nitrogen line indicates that the abundance of carbon is at least an order of magnitude larger than that of nitrogen. A Doppler shift of ~630 km/s is detected for the OVIII line, while similar shifts are obtained from the other lines. The reddening strongly suggests that the emission lines originated from the wind-wind shock zone, where the average velocity is ~600 km/s. The red-shift motion is inconsistent with a scenario in which the X-rays originate from the wind-wind collision zone in the short-period binary, and would be evidence supporting the widely separated O supergiant as a companion. This may make up the collision zone be lying behind the short-period binary. In addition to the emission lines, we also detected the RRC (radiative recombination continuum) structure from carbon around 0.49 keV. This implies the existence of additional cooler plasma.Comment: 6 pages, 4 figures, accepted to A&

Magnetosphere-Ionosphere Coupling Through E-region Turbulence 1: Energy Budget

During periods of intense geomagnetic activity, strong electric fields and currents penetrate from the magnetosphere into high-latitude ionosphere where they dissipate energy, form electrojets, and excite plasma instabilities in the E-region ionosphere. These instabilities give rise to plasma turbulence which induces non-linear currents and strong anomalous electron heating (AEH) as observed by radars. These two effects can increase the global ionospheric conductances. This paper analyzes the energy budget in the electrojet, while the companion paper applies this analysis to develop a model of anomalous conductivity and frictional heating useful in large-scale simulations and models of the geospace environment. Employing first principles, this paper proves for the general case an earlier conjecture that the source of energy for plasma turbulence and anomalous heating equals the work by external field on the non-linear current. Using a two-fluid model of an arbitrarily magnetized plasma and the quasilinear approximation, this paper describes the energy conversion process, calculates the partial sources of anomalous heating, and reconciles the apparent contradiction between the inherently 2-D non-linear current and the 3-D nature of AEH.Comment: 13 pages, 1 figure; 1st of two companion paper

Mass-Loss Rate Determination for the Massive Binary V444 Cyg using 3-D Monte-Carlo Simulations of Line and Polarization Variability

A newly developed 3-D Monte Carlo model is used, in conjunction with a multi-line non-LTE radiative transfer model, to determine the mass-loss rate of the Wolf-Rayet (W-R) star in the massive binary \object{V444 Cyg} (WN5+O6). This independent estimate of mass-loss rate is attained by fitting the observed \HeI (5876) \AA and \HeII (5412) \AA line profiles, and the continuum light curves of three Stokes parameters ((I, Q, U)) in the (V) band simultaneously. The high accuracy of our determination arises from the use of many observational constraints, and the sensitivity of the continuum polarization to the mass-loss rate. Our best fit model suggests that the mass-loss rate of the system is (\dot{M}_{\WR}=0.6(\pm 0.2) \times 10^{-5} M_{\sun} \mathrm{yr}^{-1} ), and is independent of the assumed distance to \object{V444 Cyg}. The fits did not allow a unique value for the radius of the W-R star to be derived. The range of the volume filling factor for the W-R star atmosphere is estimated to be in the range of 0.050 (for R_{\WR}=5.0 R_{\sun}) to 0.075 (for R_{\WR}=2.5 R_{\sun}). We also found that the blue-side of \HeI (5876 ) \AA and \HeII (5412) \AA lines at phase 0.8 is relatively unaffected by the emission from the wind-wind interaction zone and the absorption by the O-star atmosphere; hence, the profiles at this phase are suitable for spectral line fittings using a spherical radiative transfer model.Comment: 18 pages, 17 figures: Accepeted for publication in A&

Individual variation in levels of haptoglobin-related protein in children from Gabon

Background: Haptoglobin related protein (Hpr) is a key component of trypanosome lytic factors (TLF), a subset of highdensity lipoproteins (HDL) that form the first line of human defence against African trypanosomes. Hpr, like haptoglobin (Hp) can bind to hemoglobin (Hb) and it is the Hpr-Hb complexes which bind to these parasites allowing uptake of TLF. This unique form of innate immunity is primate-specific. To date, there have been no population studies of plasma levels of Hpr, particularly in relation to hemolysis and a high prevalence of ahaptoglobinemia as found in malaria endemic areas. Methods and Principal Findings: We developed a specific enzyme-linked immunosorbent assay to measure levels of plasma Hpr in Gabonese children sampled during a period of seasonal malaria transmission when acute phase responses (APR), malaria infection and associated hemolysis were prevalent. Median Hpr concentration was 0.28 mg/ml (range 0.03-1.1). This was 5-fold higher than that found in Caucasian children (0.049 mg/ml, range 0.002-0.26) with no evidence of an APR. A general linear model was used to investigate associations between Hpr levels, host polymorphisms, parasitological factors and the acute phase proteins, Hp, C-reactive protein (CRP) and albumin. Levels of Hpr were associated with Hp genotype, decreased with age and were higher in females. Hpr concentration was strongly correlated with that of Hp, but not CRP

Electronic Structure and Valence Band Spectra of Bi4Ti3O12

The x-ray photoelectron valence band spectrum and x-ray emission valence-band spectra (Ti K _beta_5, Ti L_alpha, O K_alpha) of Bi4Ti3O12 are presented (analyzed in the common energy scale) and interpreted on the basis of a band-structure calculation for an idealized I4/mmm structure of this material.Comment: 6 pages + 7 PostScript figures, RevTex3.0, to be published in Phys.Rev.B52 (Oct.95). Figures also available via anonymous ftp at ftp://ftp.physik.uni-osnabrueck.de/pub/apostnik/BiTiO

X-ray Emission from Nitrogen-Type Wolf-Rayet Stars

We summarize new X-ray detections of four nitrogen-type Wolf-Rayet (WR) stars obtained in a limited survey aimed at establishing the X-ray properties of WN stars across their full range of spectral subtypes. None of the detected stars is so far known to be a close binary. We report Chandra detections of WR 2 (WN2), WR 18 (WN4), and WR 134 (WN6), and an XMM-Newton detection of WR79a (WN9ha). These observations clearly demonstrate that both WNE and WNL stars are X-ray sources. We also discuss Chandra archive detections of the WN6h stars WR 20b, WR 24, and WR 136 and ROSAT non-detections of WR 16 (WN8h) and WR 78 (WN7h). The X-ray spectra of all WN detections show prominent emission lines and an admixture of cool (kT 2 keV) plasma. The hotter plasma is not predicted by radiative wind shock models and other as yet unidentified mechanisms are at work. Most stars show X-ray absorption in excess of that expected from visual extinction (Av), likely due to their strong winds or cold circumstellar gas. Existing data suggest a falloff in X-ray luminosity toward later WN7-9 subtypes, which have higher Lbol but slower, denser winds than WN2-6 stars. This provides a clue that wind properties may be a more crucial factor in determining emergent X-ray emission levels than bolometric luminosity.Comment: 42 pages, 5 tables, 10 figure

Two new rapid SNP-typing methods for classifying Mycobacterium tuberculosis complex into the main phylogenetic lineages

There is increasing evidence that strain variation in Mycobacterium tuberculosis complex (MTBC) might influence the outcome of tuberculosis infection and disease. To assess genotype-phenotype associations, phylogenetically robust molecular markers and appropriate genotyping tools are required. Most current genotyping methods for MTBC are based on mobile or repetitive DNA elements. Because these elements are prone to convergent evolution, the corresponding genotyping techniques are suboptimal for phylogenetic studies and strain classification. By contrast, single nucleotide polymorphisms (SNP) are ideal markers for classifying MTBC into phylogenetic lineages, as they exhibit very low degrees of homoplasy. In this study, we developed two complementary SNP-based genotyping methods to classify strains into the six main human-associated lineages of MTBC, the 'Beijing' sublineage, and the clade comprising Mycobacterium bovis and Mycobacterium caprae. Phylogenetically informative SNPs were obtained from 22 MTBC whole-genome sequences. The first assay, referred to as MOL-PCR, is a ligation-dependent PCR with signal detection by fluorescent microspheres and a Luminex flow cytometer, which simultaneously interrogates eight SNPs. The second assay is based on six individual TaqMan real-time PCR assays for singleplex SNP-typing. We compared MOL-PCR and TaqMan results in two panels of clinical MTBC isolates. Both methods agreed fully when assigning 36 well-characterized strains into the main phylogenetic lineages. The sensitivity in allele-calling was 98.6% and 98.8% for MOL-PCR and TaqMan, respectively. Typing of an additional panel of 78 unknown clinical isolates revealed 99.2% and 100% sensitivity in allele-calling, respectively, and 100% agreement in lineage assignment between both methods. While MOL-PCR and TaqMan are both highly sensitive and specific, MOL-PCR is ideal for classification of isolates with no previous information, whereas TaqMan is faster for confirmation. Furthermore, both methods are rapid, flexible and comparably inexpensive

Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at √ s = 8 TeV with the ATLAS detector

Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb−1 of √ s = 8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT > 120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between Emiss T > 150 GeV and Emiss T > 700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presente

The "ram effect": new insights into neural modulation of the gonadotropic axis by male odors and socio-sexual interactions

Reproduction in mammals is controlled by the hypothalamo-pituitary-gonadal (HPG) axis under the influence of external and internal factors such as photoperiod, stress, nutrition, and social interactions. Sheep are seasonal breeders and stop mating when day length is increasing (anestrus). However, interactions with a sexually active ram during this period can override the steroid negative feedback responsible for the anoestrus state, stimulate LH secretion and eventually reinstate cyclicity. This is known as the ram effect and research into the mechanisms underlying it is shedding new light on HPG axis regulation. The first step in the ram effect is increased LH pulsatile secretion in anestrus ewes exposed to a sexually active male or only to its fleece, the latter finding indicating a pheromone-like effect. Estradiol secretion increases in all ewes and this eventually induces a LH surge and ovulation, just as during the breeding season. An exception is a minority of ewes that exhibit a precocious LH surge (within 4h) with no prior increase in estradiol. The main olfactory system and the cortical nucleus of the amygdala are critical brain structures in mediating the ram effect since it is blocked by their inactivation. Sexual experience is also important since activation (increased c-fos expression) in these and other regions is greatly reduced in sexually naïve ewes. In adult ewes kisspeptin neurons in both arcuate and preoptic regions and some preoptic GnRH neurons are activated 2h after exposure to a ram. Exposure to rams also activates noradrenergic neurons in the locus coeruleus and A1 nucleus and increased noradrenalin release occurs in the posterior preoptic area. Pharmacological modulation of this system modifies LH secretion in response to the male or his odor. Together these results show that the ram effect can be a fruitful model to promote both a better understanding of the neural and hormonal regulation of the HPG axis in general and also the spe

Three-dimensional Explosion Geometry of Stripped-envelope Core-collapse Supernovae. II. Modeling of Polarization

We present modeling of line polarization to study the multidimensional geometry of stripped-envelope core-collapse supernovae (SNe). We demonstrate that a purely axisymmetric, two-dimensional (2D) geometry cannot reproduce a loop in the Stokes Q - U diagram, that is, a variation of the polarization angles along the velocities associated with the absorption lines. On the contrary, three-dimensional (3D) clumpy structures naturally reproduce the loop. The fact that the loop is commonly observed in stripped-envelope SNe suggests that SN ejecta generally have a 3D structure. We study the degree of line polarization as a function of the absorption depth for various 3D clumpy models with different clump sizes and covering factors. A comparison between the calculated and observed degree of line polarization indicates that a typical size of the clump is relatively large, ≈25% of the photospheric radius. Such large-scale clumps are similar to those observed in the SN remnant Cassiopeia A. Given the small size of the observed sample, the covering factor of the clumps is only weakly constrained (∼5%-80%). The presence of a large-scale clumpy structure suggests that the large-scale convection or standing accretion shock instability takes place at the onset of the explosion. © 2017. The American Astronomical Society. All rights reserved