Types O Research Articles

On construction of maximal parabolic centralizers of root elements and the Weyl group of type F4 in E6(K) for fields K of characteristic 2

The purpose of this paper is to give an elementary and explicit construction of maximal parabolic centralizers of root elements in the Chevalley group E6(K) and to show that the centralizer of a Seigel involution in the Weyl group W of type E6(K) is the Weyl group of type F4, or equivalently it is the stabilizer of a totaly singular line L in W, using properties of the generalized quadrangle (Ω,L) of type O6−(2).The construction here of the maximal parabolic centralizers of root elements in E6K for fields K of characteristic 2, is somewhat novel, beginning as it does, with root bases of Levi-type and root bases of unipotent type, giving an explicit construction of the group generated by these two types.

Corrosion Behavior of Materials Al5083 Alloy, 316L Stainless Steel and A681 Carbon Steel in Seawater

In this paper the corrosion behavior of different materials has been evaluated based on exposure in seawater. The laboratory immersion test technique has been applied to evaluate the effect of seawater on the corrosion behavior of different materials. In three sets of experiments, carbon steels (A681 Type O7), austenitic stainless steels (316L) and aluminium alloys (Al5083) were utilized. The specimens were fixed fully submerged in seawater. The corrosion process was evaluated using weight loss method, open-circuit potential measurements (OCP) and polarization techniques. To determine gravimetric index and the rate of penetration, samples were immersed in corrosive environment for 89 days and weighed periodically. The electrochemical experiments were conducted with a Potentiostat/Galvanostat (PGP 201) analyzer. It was connected to a PC. The Voltamaster software was used for electrochemical data analysis. A three-electrode cell composed of a specimen as a working electrode, Pt as counter electrode, and saturated calomel electrode (SCE) (Hg (l)/ Hg2Cl2 (s)) as a reference electrode were used for the tests. The weight loss tests revealed the lowest corrosion rate values for stainless steel and aluminium alloys, indicating a beneficial use for these materials in marine environments. The potentiodynamic method shows that the lowest corrosion rate in seawater (2.8 μm /year) was obtained for the Al5083 alloy, and the highest value of the corrosion rate (41.67 μm/year) for A681 carbon steel.

HLA-DRB1, IRF5, and CD28 gene polymorphisms in Egyptian patients with rheumatoid arthritis: susceptibility and disease activity.

This study was established to assess the effects of IRF5 rs10488631 and CD28 rs1980422 single-nucleotide polymorphisms (SNPs) and HLA-DRB1 shared epitope (SE) allele on the prognosis and disease activity of rheumatoid arthritis (RA) patients. A total of 150 RA patients and 150 healthy controls were genotyped for the selected SNPs by real-time PCR. HLA-DRB1 SE was determined using LAB Type SSO Class II DRB1 typing. Our results suggest that HLA-DRB1, CD28, and IRF5 significantly discriminated (p < 0.001) RA patients and healthy controls (OR of single HLA-DRB1 SE allele = 2.431, CI = 1.467-4.027, OR of two SE alleles = 11.152, CI = 2.479-50.159), (OR of CD28 risk allele C = 2.794, 95% CI = 1.973-3.956) and (OR of IRF5 risk allele C = 4.925, CI = 3.26-7.439). Rheumatoid factor (RF) seropositivity was associated with HLA-DRB1 SE (p < 0.001) and IRF5 risk allele (p < 0.001). ACPA was significantly associated only with IRF5 risk allele (p < 0.001). A better response to methotrexate therapy was found in HLA-DRB1 SE non-carriers, and CD28 TT patients. This study demonstrated associations of HLA-DRB1 SE, CD28, and IRF5 with the risk of RA. HLA-DRB1 SE and CD28 rs1980422 can be used as predictors of methotrexate therapy response.

Detection of new O-type stars in the obscured stellar cluster Tr 16-SE in the Carina Nebula with KMOS

Context.The Carina Nebula harbors a large population of high-mass stars, including at least 75 O-type and Wolf-Rayet (WR) stars, but the current census is not complete since further high-mass stars may be hidden in or behind the dense dark clouds that pervade the association.Aims.With the aim of identifying optically obscured O- and early B-type stars in the Carina Nebula, we performed the first infrared spectroscopic study of stars in the optically obscured stellar cluster Tr 16-SE, located behind a dark dust lane south ofηCar.Methods.We used the integral-field spectrograph KMOS at the ESO VLT to obtainH- andK-band spectra with a resolution ofR ≈ 4000 (Δλ≈ 5 Å) for 45 out of the 47 possible OB candidate stars in Tr 16-SE, and we derived spectral types for these stars.Results.We find 15 stars in Tr 16-SE with spectral types between O5 and B2 (i.e., high-mass stars withM ≥ 8 M⊙), only two of which were known before. An additional nine stars are classified as (Ae)Be stars (i.e., intermediate-mass pre-main-sequence stars), and most of the remaining targets show clear signatures of being late-type stars and are thus most likely foreground stars or background giants unrelated to the Carina Nebula. Our estimates of the stellar luminosities suggest that nine of the 15 O- and early B-type stars are members of Tr 16-SE, whereas the other six seem to be background objects.Conclusions.Our study increases the number of spectroscopically identified high-mass stars (M ≥ 8 M⊙) in Tr 16-SE from two to nine and shows that Tr 16-SE is one of the larger clusters in the Carina Nebula. Our identification of three new stars with spectral types between O5 and O7 and four new stars with spectral types O9 to B1 significantly increases the number of spectroscopically identified O-type stars in the Carina Nebula.

The Galactic H ii Region Luminosity Function at Radio and Infrared Wavelengths

Abstract The Galactic H ii region luminosity function (LF) is an important metric for understanding global star formation properties of the Milky Way, but only a few studies have been done, and all use relatively small numbers of H ii regions. We use a sample of 797 first Galactic quadrant H ii regions compiled from the Wide-field Infrared Survey Explorer Catalog of Galactic H ii Regions to examine the form of the LF at multiple infrared and radio wavelengths. Our sample is statistically complete for all regions powered by single stars of type O9.5V and earlier. We fit the LF at each wavelength with single and double power laws. Averaging the results from all wavelengths, the mean of the best-fit single power-law index is 〈α〉 = −1.75 ± 0.01. The mean best-fit double power-law indices are 〈α 1〉 = −1.40 ± 0.03 and 〈α 2〉 = −2.33 ± 0.04. We conclude that neither a single nor a double power law is strongly favored over the other. The LFs show some variation when we separate the H ii region sample into subsets by heliocentric distance, physical size, Galactocentric radius, and location relative to the spiral arms, but blending individual H ii regions into larger complexes does not change the value of the power-law indices of the best-fit LF models. The consistency of the power-law indices across multiple wavelengths suggests that the LF is independent of wavelength. This implies that infrared and radio tracers can be employed in place of Hα.

BAT99 126: A multiple Wolf-Rayet system in the Large Magellanic Cloud with a massive near-contact binary

Context. BAT99 126 is a multiple system in the Large Magellanic Cloud containing a Wolf-Rayet (WR) star, which has a reported spectroscopic (orbital) period of 25.5 days and a photometric (orbital) period of 1.55 days, and hence is potentially one of the shortest WR binaries known to date. Such short-period binary systems that contain a WR star in low-metallicity environments are prime candidate progenitors of black-hole (BH) mergers. Aims. By thoroughly analysing the spectroscopic and photometric data, we aim to establish the true multiplicity of BAT99 126, to characterise the orbit(s) of the system, to measure the physical properties of its individual components, and to determine the overall evolutionary status of the system. Methods. Using newly acquired high resolution spectra taken with the Ultra-violet and Visual Echelle Spectrograph mounted on the Very Large Telescope, we measured radial velocities via cross-correlation and line-profile fitting, and performed a spectral analysis of the individual components using model atmosphere codes. We estimated the age of the system and derived an evolutionary scenario for the 1.55-day system. Results. BAT99 126 comprises at least four components. The 1.55-day photometric signal originates in an eclipsing binary that consists of two O-type stars of spectral types O4 V and O6.5 V, which are both rapid rotators (300 km s−1 and 230 km s−1, respectively). From the broad emission lines of the WR star, we derived a spectral type WN2.5-3. We further reject the previously reported 25.5-d period for the WR star and find that there is no detectable orbital motion within our uncertainties. The presence of additional narrow Si III and O II lines in the composite spectrum corresponds to a fourth component, a B1 V star. There is clear evidence that the B-type star shows a radial velocity variation; however, the data do not allow for a determination of the orbital parameters. The configurations of the B-type star, the WR star, and possible additional undetected components remain unknown. We derived masses for the O-type components of 36 ± 5 M⊙ and 15 ± 2 M⊙, respectively, and estimated the age of the system to be 4.2 Myr. We find evidence of previous or ongoing mass-transfer between the two O-type components and infer initial masses of 23 M⊙ for the O4 V star and 29 M⊙ for the O6.5 V star. The O+O binary likely went through a phase of conservative mass transfer and is currently a near-contact system. Conclusion. We show that BAT99 126 is a multiple – quadruple or higher-order – system with a total initial mass of at least 160 M⊙. The 1.55-day O+O binary most likely will not evolve towards a BH+BH merger, but instead will merge before the collapse of the components to BHs.

NGC 7538 IRS1—an O Star Driving an Ionized Jet and Giant N–S Outflow

Abstract NGC 7538 IRS 1 is a very young embedded O star driving an ionized jet and accreting mass with an accretion rate &gt;10−4 yr−1, which is quenching the hypercompact H ii region. We use SOFIA GREAT data, Herschel PACS and SPIRE archive data, SOFIA FORCAST archive data, Onsala 20 m and CARMA data, and JCMT archive data to determine the properties of the O star and its outflow. IRS 1 appears to be a single O star with a bolometric luminosity &gt;1 × 105 , i.e., spectral type O7 or earlier. We find that IRS 1 drives a large molecular outflow with the blueshifted northern outflow lobe extending to ∼280″ or 3.6 pc from IRS 1. Near IRS 1 the outflow is well aligned with the ionized jet. The dynamical timescale of the outflow is ∼1.3 × 105 yr. The total outflow mass is ∼130 . We determine a mass outflow rate of 1.0 × 10−3 yr−1, roughly consistent with the observed mass accretion rate. We observe strong high-velocity [C ii] emission in the outflow, confirming that strong UV radiation from IRS 1 escapes into the outflow lobes and is ionizing the gas. Many O stars may form like low-mass stars, but with a higher accretion rate and in a denser environment. As long as the accretion stays high enough to quench the H ii region, the star will continue to grow. When the accretion rate drops, the H ii region will rapidly start to expand.

Triggered high-mass star formation in the H iiregion W 28 A2: A cloud–cloud collision scenario

AbstractWe report on a study of the high-mass star formation in the H ii region W 28 A2 by investigating the molecular clouds that extend over ∼5–10 pc from the exciting stars using the 12CO and 13CO (J = 1–0) and 12CO (J = 2–1) data taken by NANTEN2 and Mopra observations. These molecular clouds consist of three velocity components with CO intensity peaks at VLSR ∼ −4 km s−1, 9 km s−1, and 16 km s−1. The highest CO intensity is detected at VLSR ∼ 9 km s−1, where the high-mass stars with spectral types O6.5–B0.5 are embedded. We found bridging features connecting these clouds toward the directions of the exciting sources. Comparisons of the gas distributions with the radio continuum emission and 8 μm infrared emission show spatial coincidence/anti-coincidence, suggesting physical associations between the gas and the exciting sources. The 12CO J = 2–1 to 1–0 intensity ratio shows a high value (≳0.8) toward the exciting sources for the −4 km s−1 and +9 km s−1 clouds, possibly due to heating by the high-mass stars, whereas the intensity ratio at the CO intensity peak (VLSR ∼ 9 km s−1) decreases to ∼0.6, suggesting self absorption by the dense gas in the near side of the +9 km s−1 cloud. We found partly complementary gas distributions between the −4 km s−1 and +9 km s−1 clouds, and the −4 km s−1 and +16 km s−1 clouds. The exciting sources are located toward the overlapping region in the −4 km s−1 and +9 km s−1 clouds. Similar gas properties are found in the Galactic massive star clusters RCW 38 and NGC 6334, where an early stage of cloud collision to trigger the star formation is suggested. Based on these results, we discuss the possibility of the formation of high-mass stars in the W 28 A2 region being triggered by cloud–cloud collision.

Investigation of SSO characteristics in grid‐connected PMSGs system

In recent years, a new type SSO issue, which has occurred in direct-drive permanent magnetic synchronous generators (PMSGs) based wind farm, brings a new challenge to the stability of the power system. In this paper, the SSO issue in grid-connected PMSGs system is studied by the eigenvalue analysis. The linearised state-space model of this system is built firstly. The impacts on the SSO characteristics from short-circuit ratio (SCR), impedance-frequency characteristic, resonant frequency of AC network and control parameters of PMSGs are observed by the root loci analysis. After that, electromagnetic transient simulation is carried out to verify the eigenvalue analysis. Meanwhile, the participation factors of SSO mode are calculated to analyse the subsynchronous control interaction (SSCI) between AC network and PMSG. The result shows that there is a SSO mode which is greatly influenced by AC network and DC capacitor, grid side converter (GSC) control of PMSG. The characteristics of AC network will affect the SSCI between AC network and PMSG.

A geometry of the generalized quadrangle (Ω,𝔏) of type O6−(2) and Lie algebras of type E6 with characteristic two

The purpose of this paper is to study certain geometric properties of generalized quadrangle [Formula: see text] of type [Formula: see text]. We define certain root elements which generate a Lie algebra of type [Formula: see text] for fields [Formula: see text] of characteristic two. The construction will be mainly based on the geometric properties of the generalized quadrangle [Formula: see text]. In fact, we will explicity construct a Chevalley base of this Lie algebra.

A Modern Census of the Broadest Diffuse Interstellar Bands

Abstract We present the results of a ground-based observing campaign designed to produce the first homogeneous census of the population of the broadest (FWHM ≥ 6 Å) diffuse interstellar bands (DIBs) in the Galaxy. New low-resolution optical spectra for 21 sightlines spanning a reddening range of three magnitudes, using stars of spectral types O7 through A3, were examined together with corresponding higher-resolution echelle spectra. A new pipeline developed for the reduction and analysis of the low-resolution spectra is presented. Of the 34 broad features reported in the literature, 22 are covered in this survey. Of those 22, 9 are confirmed as broad DIBs, 2 are rejected, and the remaining 11 are uncertain, due to severe blending with stellar and/or telluric lines. No new broad DIBs are identified. New homogeneous measurements of the strength of the broad 6177 Å DIB are compared with the corresponding strengths of five narrower DIBs known to trace different phases of the diffuse ISM: the 4963 Å C2-DIB (which can reside in diffuse molecular gas) and the 5780, 5797, 6284, and 6613 Å DIBs (which primarily trace atomic gas). The 6177 Å DIB correlates quite well with the 5780 and 6284 Å DIBs but shows no correlation with the 4963 Å C2-DIB—suggesting that its carrier is found primarily in the atomic gas.

Model atmosphere analysis of two new early–type O4 dwarfs stars

Abstract We present a synthetic spectra study of two new galactic early-type O4 dwarf stars(ALS 19618 and BD+50886) with high signal-to-noise ratio, typically S/N ∼ 300, medium-rosalution R ∼ 2500 optical spectra of O4 dwarfs stars from Galactic O-Stars Spectroscopic Survey (GOSSS), The main stellar parameters (Teff, surface gravity, rotational velocity) have been established using non-LTE, line-blanketed, atmospheric models calculated by TLUSTY204 and SYNSPEC49.

Photometric Strömgren-Hβ Quantification for O and B Stars of Luminosity Class V

In any photometric system, the relationship between the spectral type and the intrinsic colors is fundamental for the photometric stellar classification and for a reliable derivation of stellar parameters. Such relationships are being constantly verified and improved based on larger and better samples. The capability of the Strömgren-Hβ photometry to provide reddening-free quantities allows the classification of reddened stars over the entire spectral sequence. However, a detailed consistent tabulation of the uvbyβ quantities for the O-B9 part of the main sequence is currently warranted. We combine spectral types and photometry from the literature to provide a new empirical tabulation of the intrinsic color b − y, color differences c1, m1, [c1] and [m1] and the Hβ index for main-sequence (luminosity class V) stars of spectral types O4.5 through B9.5 in terms of spectral sub-types. Our survey is based on more than 1400 stars. We use the established c1 versus b − y intrinsic line and the accepted reddening slopes to obtain dereddened quantities and then calculate their median values as a function of the spectral sub-type. The classification ability of the system in this spectral range is reliable and the photometric quantities are not affected by the stellar rotation.

An Empirical Template Library of Stellar Spectra for a Wide Range of Spectral Classes, Luminosity Classes, and Metallicities Using SDSS BOSS Spectra

Abstract We present a library of empirical stellar spectra created using spectra from the Sloan Digital Sky Survey’s Baryon Oscillation Spectroscopic Survey. The templates cover spectral types O5 through L3, are binned by metallicity from −2.0 dex through +1.0 dex, and are separated into main-sequence (dwarf) stars and giant stars. With recently developed M dwarf metallicity indicators, we are able to extend the metallicity bins down through the spectral subtype M8, making this the first empirical library with this degree of temperature and metallicity coverage. The wavelength coverage for the templates is from 3650 to 10200 Å at a resolution of better than R ∼ 2000. Using the templates, we identify trends in color space with metallicity and surface gravity, which will be useful for analyzing large data sets from upcoming missions like the Large Synoptic Survey Telescope. Along with the templates, we are releasing a code for automatically (and/or visually) identifying the spectral type and metallicity of a star.

Helium Ionization in the Diffuse Ionized Gas Surrounding UCH ii Regions

Abstract We present measurements of the singly ionized helium-to-hydrogen ratio ( ) toward diffuse gas surrounding three ultracompact H ii (UCH ii) regions: G10.15-0.34, G23.46-0.20, and G29.96-0.02. We observe radio recombination lines of hydrogen and helium near 5 GHz using the GBT to measure the ratio. The measurements are motivated by the low helium ionization observed in the warm ionized medium and in the inner Galaxy diffuse ionized regions. Our data indicate that the helium is not uniformly ionized in the three observed sources. Helium lines are not detected toward a few observed positions in sources G10.15-0.34 and G23.46-0.20, and the upper limits of the ratio obtained are 0.03 and 0.05, respectively. The selected sources harbor stars of type O6 or hotter as indicated by helium line detection toward the bright radio continuum emission from the sources with mean value 0.06 ± 0.02. Our data thus show that helium in diffuse gas located a few parsecs away from the young massive stars embedded in the observed regions is not fully ionized. We investigate the origin of the nonuniform helium ionization and rule out the possibilities (a) that the helium is doubly ionized in the observed regions and (b) that the low values are due to additional hydrogen ionizing radiation produced by accreting low-mass stars. We find that selective absorption of ionizing photons by dust can result in low helium ionization but needs further investigation to develop a self-consistent model for dust in H ii regions.

Development of TLSER model and QSAR model for predicting partition coefficients of hydrophobic organic chemicals between low density polyethylene film and water

Partition coefficients are vital parameters for measuring accurately the chemicals concentrations by passive sampling devices. Given the wide use of low density polyethylene (LDPE) film in passive sampling, we developed a theoretical linear solvation energy relationship (TLSER) model and a quantitative structure-activity relationship (QSAR) model for the prediction of the partition coefficient of chemicals between LDPE and water (Kpew). For chemicals with the octanol–water partition coefficient (log Kow) <8, a TLSER model with Vx (McGowan volume) and qA− (the most negative charge on O, N, S, X atoms) as descriptors was developed, but the model had relatively low determination coefficient (R2) and cross-validated coefficient (Q2). In order to further explore the theoretical mechanisms involved in the partition process, a QSAR model with four descriptors (MLOGP (Moriguchi octanol-water partition coeff.), P_VSA_s_3 (P_VSA-like on I-state, bin 3), Hy (hydrophilic factor) and NssO (number of atoms of type ssO)) was established, and statistical analysis indicated that the model had satisfactory goodness-of-fit, robustness and predictive ability. For chemicals with log KOW>8, a TLSER model with Vx and a QSAR model with MLOGP as descriptor were developed. This is the first paper to explore the models for highly hydrophobic chemicals. The applicability domain of the models, characterized by the Euclidean distance-based method and Williams plot, covered a large number of structurally diverse chemicals, which included nearly all the common hydrophobic organic compounds. Additionally, through mechanism interpretation, we explored the structural features those governing the partition behavior of chemicals between LDPE and water.

PROBING THE MASSES AND RADII OF DONOR STARS IN ECLIPSING X-RAY BINARIES WITH THESWIFTBURST ALERT TELESCOPE

Physical parameters of both the mass donor and compact object can be constrained in X-ray binaries with well-defined eclipses, as our survey of wind-fed supergiant X-ray binaries (SGXBs) IGR J16393-4643, IGR J16418-4532, IGR J16479-4514, IGR J18027-2016 and XTE J1855-026 reveals. Using the orbital period and Kepler's third law, we express the eclipse half-angle in terms of radius, inclination angle and the sum of the masses. Pulse-timing and radial velocity curves can give masses of both the donor and compact object as in the case of the "double-lined" binaries IGR J18027-2016 and XTE J1855-026. The eclipse half angles are 15 (+3,-2), 31.7 (+0.7,-0.8), 32 +/- 2, 34 +/- 2 and 33.6 +/- 0.7 degrees for IGR J16393-4643, IGR J16418-4532, IGR J16479-4514, IGR J18027-2016 and XTE 1855-026, respectively. In wind-fed systems, the primary not exceeding the Roche-lobe size provides an upper limit on system parameters. In IGR J16393-4643, spectral types of B0 V or B0-5 III are found to be consistent with the eclipse duration and Roche-lobe, but the previously proposed donor stars in IGR J16418-4532 and IGR J16479-4514 were found to be inconsistent with the Roche-lobe size. Stars with spectral types O7.5 I and earlier are possible. For IGR J18027-2016, the mass and radius of the donor star lie between 18.6--19.4 $M_\odot$ and 17.4--19.5 $R_\odot$. We constrain the neutron star mass between 1.37--1.43 $M_\odot$. We find the mass and radius of the donor star in XTE J1855-026 to lie between 19.6--20.2 $M_\odot$ and 21.5--23.0 $R_\odot$. The neutron star mass was constrained to 1.77--1.82 $M_\odot$. Eclipse profiles are asymmetric in IGR J18027-2016 and XTE J1855-026, which we attribute to accretion wakes.

Analysis for 2 samples with HLA-DQB1 allele dropout at exon 2 in sequence-based typing

To explore the reason for HLA-DQB1 allele dropout during routine sequence-based typing(SBT) in order to improve the accuracy of typing. Two thousand samples derived from HLA high-resolution typing laboratory were typed for HLA-DQB1 locus using an AlleleSEQR HLA-DQB1 SBT kit. Non-conclusive results and "abnormal" sequencing samples were retyped using a LABType rSSO HD HLA-DQB1 kit and further analyzed with both sequence-specific primers and group-specific primers and sequenced for haplotype analysis. Among the 2000 samples, 2 samples with no conclusive result were identified. The heterozygosity was confirmed with both the LAB Type SSO HD HLA-DQB1 kit and PCR-SBT in house method. Subsequent HLA-DQB1 cloning and haplotype sequencing have elucidated that HLA-DQB1*02:02 dropped out at exon 2 for the first sample and HLA-DQB1*02:01:01 dropped out at exon 2 for the second sample during PCR amplification. No novel nucleotide mutation was found. Our results indicated that preferential amplification at exon 2 of DQB1 may result in allele dropout in exon 2 sequences during HLA-DQB1 SBT test. This may provide useful information for HLA genotyping.

Distribution of phylogenetic groups, sequence type ST131, and virulence-associated traits among Escherichia coli isolates from men with pyelonephritis or cystitis and healthy controls

Urinary tract infections (UTI), which are mostly caused by Escherichia coli, are an important public health problem worldwide. Although men experience diverse UTI syndromes, there have been relatively few molecular-epidemiological studies of UTI pathogenesis in men. We studied the distribution of 22 E. coli virulence factor (VF) genes, major phylogenetic groups, sequence type ST131, and UTI-associated O antigens among 101 pyelonephritis, 153 cystitis and 135 fecal healthy control E. coli isolates from men aged 30–70 years in a regional area of NSW, Australia. Overall, the studied traits exhibited a prevalence gradient across these groups, highest in pyelonephritis, intermediate in cystitis, and lowest among fecal isolates. Differences in virulence gene prevalence between cystitis and pyelonephritis isolates were limited to eight genes. The UTI-associated O antigens were also distributed widely, but types O6, O25 and O75 were significantly associated with pyelonephritis. The ST131 clonal group, which accounted for 13% of isolates overall (22% of group B2 isolates), likewise exhibited a significant descending prevalence gradient from pyelonephritis (36%), through cystitis (8%), to fecal (0%) isolates. These findings contribute to better understanding of the pathogenesis of UTIs in men and identify specific VF genes and O types, and a prominent clonal group (ST131), as being important in UTI pathogenesis in this population.

Orbital and physical parameters of the spectroscopic binary HD37737

We report the physical and orbital parameters of the visible component of the spectroscopic binary HD37737 (m V = 8.03). The observations were performed with the 1.2-m telescope of the Kourovka Astronomical Observatory of the Ural Federal University in 2012 and the 6-m BTA telescope of the SAO RAS in 2007 and 2009. Radial velocities were measured separately from each spectral line of the list by the cross-correlation method with a synthetic spectrum. The latter was calculated using the grids of non-LTE model atmospheres with solar chemical compositions. A significant difference in the epochs of observations (2005–2012) allowed to refine the orbital period of the star (7 · d 84705) and the orbital elements of the binary system. We obtained an estimate of the mass function f(m) = 0.23 ± 0.02M ⊙. The best agreement between the synthetic and observed spectra is achieved at T eff = 30 000 K and log g = 3.50 according to the observations on both instruments. The obtained parameters correspond to a star of spectral type O9.5 III, with mass estimated at 26 ± 2M ⊙. The minimum mass estimate of the secondary component of the binary is 6.2 ± 0.5M ⊙. We have discovered a fact that the velocities, obtained from different spectral lines, differ, which is typical for giant stars. Engaging additional spectra, obtained in 2005 with the 2.1-m KPNO telescope, we investigated the effect of this fact on the estimate of the speed of the system’s center of mass. The difference in the velocities of various lines is approximately the same in the spectra, obtained at all the three instruments. The obtained ratios suggest that the deeper layers of the atmosphere of the star are moving with a greater velocity than the outer layers. Depending on the line, the estimate of the heliocentric velocity of the binary’s center of mass varies in the range from −11 to 1 km/s.