High-resolution X-ray spectroscopy of the ultracompact LMXB pulsar 4U 1626-67

[abridged] We report results from four recent observations of the ultracompact LMXB pulsar 4U 1626-67. All the observations obtained high-resolution X-ray spectra of the system, two from the Chandra X-ray Observatory using the HETGS, and two from the XMM-Newton Observatory using the RGS as well as the EPIC PN and MOS. These data allow us to study in detail the prominent Ne and O emission line complexes which make 4U 1626-67 unique among LMXBs. The observations were spaced over a period of 3 years for a total observing time of 238 ks, allowing us to monitor the line regions as well as the overall source flux, continuum spectrum, and timing properties. The structure of the emission lines and the ratios of the components of the helium-like Ne IX and O VII triplets support the hypothesis that they are formed in the high-density environment of the accretion disk. We do not find any significant changes in the line widths or ratios over this time period, though we note that the line equivalent widths decrease. We are able to place constraints on the strengths of the Ne K, Fe L, and O K photoelectric absorption edges, and find that the data do not require an overabundance of Ne or O in the system relative to the expected ISM values. We find that the pulsar is still spinning down, and note that the pulse profile has changed significantly from what was found prior to the torque reversal in 1990, suggesting that this event may be linked to a change in the geometry of the accretion column. The flux of 4U 1626-67 continues to decrease, in keeping with the trend of the last approximately 30 years over which it has been observed. Taking into consideration current theory on disk stability, we expect that 4U 1626-67 will enter a period of quiescence in 2-15 years.Comment: 10 pages, 7 figures, submitted to Ap

Properties of Highly c-axis Oriented Single-crystalline ZnO Layers Grown by Sputter Epitaxy for Hydrogen Gas and UV Sensors

We have previously developed ultra-high vacuum RF magnetron sputtering systems. They can produce high-quality single-crystalline compound semiconductor layers without grain boundaries on sapphire substrates. We aim to utilize these semiconductor layers in high-sensitivity sensor devices used for detecting leakage hydrogen gas (H2) from storage facilities and for early finding UV irradiation from accidental hydrogen flames. This study demonstrates the sensitivity of our single- crystalline zinc oxide (ZnO) layers to detect H2 and UV irradiation. In the result, the H2 sensor showed sufficient sensitivity to detect up to 5 ppm of H2. Moreover, the UV sensor could detect UV irradiation of 0.01 mW/cm2 at wavelength of 360 nm. Although as-grown single-crystalline ZnO layers is used without employing any sensitivity-enhancement techniques, these sensors could achieve the sensitivity equal to that of commercial devices. Thus, we considered that our single-crystalline ZnO layers using sensitivity-enhancement techniques could yield ultra-high sensitivity devises

AS-ALPS: a database for analyzing the effects of alternative splicing on protein structure, interaction and network in human and mouse

We have constructed a database, AS-ALPS (alternative splicing-induced alteration of protein structure), which provides information that would be useful for analyzing the effects of alternative splicing (AS) on protein structure, interactions with other bio-molecules and protein interaction networks in human and mouse. Several AS events have been revealed to contribute to the diversification of protein structure, which results in diversification of interaction partners or affinities, which in turn contributes to regulation of bio-molecular networks. Most AS variants, however, are only known at the sequence level. It is important to determine the effects of AS on protein structure and interaction, and to provide candidates for experimental targets that are relevant to network regulation by AS. For this purpose, the three-dimensional (3D) structures of proteins are valuable sources of information; however, these have not been fully exploited in any other AS-related databases. AS-ALPS is the only AS-related database that describes the spatial relationships between protein regions altered by AS (‘AS regions’) and both the proteins’ hydrophobic cores and sites of inter-molecular interactions. This information makes it possible to infer whether protein structural stability and/or protein interaction are affected by each AS event. AS-ALPS can be freely accessed at http://as-alps.nagahama-i-bio.ac.jp and http://genomenetwork.nig.ac.jp/as-alps/

Magnetic Fields of Accreting X-Ray Pulsars with the Rossi X-Ray Timing Explorer

Using a consistent set of models, we parameterized the X-ray spectra of all accreting pulsars in the Rossi X-ray Timing Explorer database which exhibit Cyclotron Resonance Scattering Features (CRSFs, or cyclotron lines). These sources in our sample are Her X-1, 4U 0115+63, Cen X-3, 4U 1626-67, XTE J1946-274, Vela X-1, 4U 1907+09, 4U 1538-52, GX 301-2, and 4U 0352+309 (X Per). We searched for correlations among the spectral parameters, concentrating on how the cyclotron line energy relates to the continuum and therefore how the neutron star B-field influences the X-Ray emission. As expected, we found a correlation between the CRSF energy and the spectral cutoff energy. However, with our consistent set of fits we found that the relationship is more complex than what has been reported previously. Also, we found that not only does the width of the cyclotron line correlate with the energy (as suggested by theory), but that the width scaled by the energy correlates with the depth of the feature. We discuss the implications of these results, including the possibility that accretion directly affects the relative alignment of the neutron star spin and dipole axes. Lastly, we comment on the current state of fitting phenomenological models to spectra in the RXTE/BeppoSAX era and the need for better theoretical models of the X-Ray continua of accreting pulsars.Comment: 36 Pages, 9 Figures, 9 Tables, ApJ in pres

Structural basis for the adaptation and function of chlorophyll f in photosystem I

Chlorophylls (Chl) play pivotal roles in energy capture, transfer and charge separation in photosynthesis. Among Chls functioning in oxygenic photosynthesis, Chl f is the most red-shifted type first found in a cyanobacterium Halomicronema hongdechloris. The location and function of Chl f in photosystems are not clear. Here we analyzed the high-resolution structures of photosystem I (PSI) core from H. hongdechloris grown under white or far-red light by cryo-electron microscopy. The structure showed that, far-red PSI binds 83 Chl a and 7 Chl f, and Chl f are associated at the periphery of PSI but not in the electron transfer chain. The appearance of Chl f is well correlated with the expression of PSI genes induced under far-red light. These results indicate that Chl f functions to harvest the far-red light and enhance uphill energy transfer, and changes in the gene sequences are essential for the binding of Chl f

Genetic heterogeneity within an electrophoretic phenotype of phosphoglucose isomerase in a Japanese population

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65884/1/j.1469-1809.1979.tb00662.x.pd

Molecular Dynamics Simulations of Lipid Bilayers: Major Artifacts due to Truncating Electrostatic Interactions

We study the influence of truncating the electrostatic interactions in a fully hydrated pure dipalmitoylphosphatidylcholine (DPPC) bilayer through 20 ns molecular dynamics simulations. The computations in which the electrostatic interactions were truncated are compared to similar simulations using the Particle-Mesh Ewald (PME) technique. All examined truncation distances (1.8 to 2.5 nm) lead to major effects on the bilayer properties, such as enhanced order of acyl chains together with decreased areas per lipid. The results obtained using PME, on the other hand, are consistent with experiments. These artifacts are interpreted in terms of radial distribution functions $g(r)$ of molecules and molecular groups in the bilayer plane. Pronounced maxima or minima in g(r) appear exactly at the cutoff distance indicating that the truncation gives rise to artificial ordering between the polar phosphatidyl and choline groups of the DPPC molecules. In systems described using PME, such artificial ordering is not present

Testosterone production during puberty in two 46,XY patients with disorders of sex development and novel NR5A1 (SF-1) mutations

BACKGROUND: Steroidogenic factor 1 (SF-1, NR5A1) is a key transcriptional regulator of many genes involved in the hypothalamic–pituitary–gonadal axis and mutations in NR5A1 can result in 46,XY disorders of sex development (DSD). Patients with this condition typically present with ambiguous genitalia, partial gonadal dysgenesis, and absent/rudimentary Müllerian structures. In these cases, testosterone is usually low in early infancy, indicating significantly impaired androgen synthesis. Further, Sertoli cell dysfunction is seen (low inhibin B, anti-Müllerian hormone). However, gonadal function at puberty in patients with NR5A1 mutations is unknown. SUBJECTS AND METHODS: Clinical assessment, endocrine evaluation, and genetic analysis were performed in one female and one male with 46,XY DSD who showed spontaneous virilization during puberty. The female patient presented at adolescence with clitoral hypertrophy, whereas the male patient presented at birth with severe hypospadias and entered puberty spontaneously. Molecular analysis of NR5A1 was performed followed by in vitro functional analysis of the two novel mutations detected. RESULTS: Testosterone levels were normal during puberty in both patients. Analysis of NR5A1 revealed two novel heterozygous missense mutations in the ligand-binding domain of SF-1 (patient 1: p.L376F; patient 2: p.G328V). The mutant proteins showed reduced transactivation of the CYP11A promoter in vitro. CONCLUSION: Patients with 46,XY DSD and NR5A1 mutations can produce sufficient testosterone for spontaneous virilization during puberty. Phenotypic females (46,XY) with NR5A1 mutations can present with clitoromegaly at puberty, a phenotype similar to other partial defects of androgen synthesis or action. Testosterone production in 46,XY males with NR5A1 mutations can be sufficient for virilization at puberty. As progressive gonadal dysgenesis is likely, gonadal function should be monitored in adolescence and adulthood, and early sperm cryopreservation considered in male patients if possible

Cerebral air embolism as a complication of peptic ulcer in the gastric tube: case report

<p>Abstract</p> <p>Background</p> <p>The reported incidence of ulcer formation in the gastric tube in esophageal replacement is rare.</p> <p>Case Presentation</p> <p>This is the first report of a case of cerebral air embolism as a result of spontaneous perforation of an ulcer in the constructed gastric tube into the pulmonary vein during post-operative follow-up in a patient with esophageal cancer.</p> <p>Conclusions</p> <p>Cerebral air embolism is a rare complication of penetrating gastric ulcer, but should be considered in patients with a history of esophagectomy with gastric conduit that present with acute neurologic findings.</p

Triangulation supports agricultural spread of the Transeurasian languages

The origin and early dispersal of speakers of Transeurasian languages, i.e., Japanese, Korean, Tungusic, Mongolic and Turkic, is among the most disputed issues of Eurasian population history. A key problem is the relationship between linguistic dispersals, agricultural expansions and population movements. Here we address this question through ‘triangulating’ genetics, archaeology and linguistics in a unified perspective. We report new, wide-ranging datasets from these disciplines, including the most comprehensive Transeurasian agropastoral and basic vocabulary presented to date, an archaeological database of 255 Neolithic and Bronze Age sites from Northeast Asia, and the first collection of ancient genomes from Korea, the Ryukyu islands and early cereal farmers in Japan, complementing previously published genomes from East Asia. Challenging the traditional ‘Pastoralist Hypothesis’, we show that the common ancestry and primary dispersals of Transeurasian languages can be traced back to the first farmers moving across Northeast Asia from the Early Neolithic onwards, but that this shared heritage has been masked by extensive cultural interaction since the Bronze Age. As well as marking significant progress in the three individual disciplines, by combining their converging evidence, we show that the early spread of Transeurasian speakers was driven by agriculture.Introduction Linguistics Archaeology Genetics Discussion: Triangulation Method