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Sample records for ob identifikatsii izomera

  1. Are Field OB Stars Alone?

    NASA Astrophysics Data System (ADS)

    Oey, Sally

    2005-07-01

    This SNAP program offers an inexpensive, simple program to search for low-mass companions of field OB stars. Do field OB stars exist in true isolation, as suggested by a recent Galactic study, or are they the tip of the iceberg on a small cluster of low-mass stars as predicted by the cluster mass function and stellar IMF? Short ACS/WFC V and I observations proposed here may easily resolve this issue for field OB stars in the Small Magellanic Cloud. Truly isolated OB stars represent a theoretical challenge and variation from clusters, in mode of star formation, and have important consequences for our understanding of the field stellar population in galaxies. Small clusters around the field OB stars, on the other hand, may confirm the universality of the stellar clustering law and IMF.

  2. Longitudinal evaluation of hepatic lipid deposition and composition in ob/ob and ob/+ control mice.

    PubMed

    Ye, Qiong; Danzer, Carsten Friedrich; Fuchs, Alexander; Vats, Divya; Wolfrum, Christian; Rudin, Markus

    2013-09-01

    Obesity is associated with insulin resistance (IR) and hepatosteatosis. Understanding the link between IR and hepatosteatosis could be relevant to chronic clinical outcomes. The objective of this study was to quantitatively assess lipid deposition (fractional lipid mass, fLM) and composition (fraction of polyunsaturated lipids, fPUL and mean chain length, MCL) in livers of ob/ob mice, a genetic model of obesity and mild diabetes, and ob/+ heterozygous control animals in a noninvasive manner using (1) H-MRS at 9.4T. For accurate quantification, intensity values were corrected for differences in T2 values while T1 effects were considered minimal due to the long TR values used. Values of fLM, fPUL and MCL were derived from T2 -corrected signal intensities of lipids and water resonance. Hepatic lipid signals were compared with fasted plasma insulin, glucose and lipid levels. Statistically significant correlations between fPUL and fasting plasma insulin/glucose levels were found in adolescent ob/ob mice. A similar correlation was found between fLM and fasting plasma insulin levels; however, the correlation between fLM and fasting plasma glucose levels was less obvious in adolescent ob/ob mice. These correlations were lost in adult ob/ob mice. The study showed that in adolescent ob/ob mice, there was an obvious link between lipid deposition/composition in the liver and plasma insulin/glucose levels. This correlation was lost in adult animals, probably due to the limited lipid storage capacity of the liver.

  3. Ice Jams the Ob River

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Russia's Ob River flows from south to north, and each summer, it thaws in the same direction. The result is that an ice jam sits downstream from thawed portions of the river, which is laden with heavy runoff from melted snow. On June 29, 2007, the Moderate Resolution Imaging Spectroradiometer (MODIS) flying on NASA's Terra satellite captured this image of the almost completely thawed Ob River. The scene is typical for early summer. South of the ice jam, the Gulf of Ob is swollen with pent-up run-off, and upstream from that, the river is widened as well. Unable to carve through frozen land, the river has little choice but to overflow its banks. For a comparison of early summer and autumn conditions, see Flooding on the Ob River in the Earth Observatory's Natural Hazards section. Besides the annual overflow, this image captures other circumstances of early summer. Sea ice is retreating from the Kara Sea. A lingering line of snow cover snakes its way along the Ob River, to the west. And while the land is lush and green in the south, it appears barren and brown in the north. Near the mouth of the river and the Kara Sea, the land is cold-adapted tundra, with diminutive plants and a short growing season. Just as the ice plugging the river had yet to thaw in the Far North's short summer, the tundra had not yet to greened up either. In this image it still appears lifeless beige. NASA image courtesy Jeff Schmaltz, MODIS Rapid Response Team, Goddard Space Flight Center

  4. Adrenalectomy fails to stimulate brown adipose tissue metabolism in ob/ob mice fed glucose.

    PubMed

    Kim, H K; Romsos, D R

    1988-11-01

    Adrenalectomy arrests the development of obesity in ob/ob mice fed nonpurified high-starch diets partly by stimulating the low thermogenic activity of brown adipose tissue (BAT). However, adrenalectomy fails to suppress the development of obesity in ob/ob mice fed a purified high-glucose diet. Effects of adrenalectomy on BAT metabolism in ob/ob mice fed purified high-starch or high-glucose diets were therefore examined. Adrenalectomy markedly decreased the efficiency of energy retention and increased BAT metabolism (as assessed by GDP binding to BAT mitochondria, GDP-inhibitable acetate- or chloride-induced mitochondrial swelling, and by rates of norepinephrine turnover in BAT) in ob/ob mice fed a high-starch purified diet but had only minimal effects on energy efficiency or BAT metabolism in ob/ob mice fed a high-glucose purified diet. Plasma insulin concentrations decreased and thyroxine concentrations increased in adrenalectomized ob/ob mice fed the high-starch diet; changes in these hormones were less pronounced in adrenalectomized ob/ob mice fed the high-glucose diet. Consumption of glucose mimics effects of adrenal secretions on BAT metabolism in ob/ob mice.

  5. Effect of leptin administration on myelination in ob/ob mouse cerebrum after birth.

    PubMed

    Hashimoto, Ryuju; Matsumoto, Akihiro; Udagawa, Jun; Hioki, Kyoji; Otani, Hiroki

    2013-01-09

    Brain weight and size are known to be reduced in adult leptin-deficient Lep/Lep (OB) mice when compared with the wild-type (+/+) mice (C57BL/6: B6). We here analyzed leptin's effects on myelination by examining morphometrically the myelin sheath (MS) in the cerebrum of postnatal day (P) 14 and P28 OB that had received leptin 1 nmol/capita/day from P7 to P14 or P28 (OB+lep), in comparison with OB and B6. We examined myelin basic protein (MBP) mRNA levels and the differentiation of oligodendrocytes by comparing the number of oligodendrocyte precursor cells (OPCs) and the mature oligodendrocytes in the cerebrum between OB, OB+lep, and B6 on P14 and P28. MBP-mRNA expression was lower in OB than in B6 on P14 and P28. On P14, it was higher in OB+lep than in OB but was still lower than in B6, whereas on P28 it was even higher in OB+lep than in B6. On P28, the radii of myelinated axons were larger in OB than in B6 and OB+lep. The MS on P28 was significantly thinner in OB than in B6, but there was no significant difference between OB and OB+lep. There were significantly fewer mature oligodendrocytes in OB and OB+lep than in B6 on P28, whereas on P14 there were significantly fewer OPCs in OB and OB+lep than in B6. Our results suggested that leptin regulates the myelination of oligodendrocytes and that the replenishment of leptin in OB recovered myelination but did not affect the differentiation of OPCs from P7 to P28.

  6. Sequentially triggered star formation in OB associations

    NASA Astrophysics Data System (ADS)

    Preibisch, Thomas; Zinnecker, Hans

    We discuss observational evidence for sequential and triggered star formation in galactic and extragalactic OB associations. We will first review in detail the star formation process in the Scorpius-Centaurus OB association, the nearest OB association to the Sun, where several recent extensive studies have provided comprehensive information on the stellar content and the ages of the different OB subgroups. These data have allowed us to reconstruct the star formation history of the association in some detail and provided important insight into the activity in the rho Oph and Lupus dark clouds, and with the origin of several young stellar groups in the southern sky. After discussing evidence for triggered star formation in and around various other Galactic OB associations (e.g. Ori OB1, Per OB2) we will compare the observational results with recent models of rapid star formation in the turbulent interstellar medium (cf. Briceno et al. chapter in Protostars and Planets V, in press).

  7. OB or Not OB: Idiosyncratic utilization of the tRNA-binding OB-fold domain in unicellular, pathogenic eukaryotes.

    PubMed

    Kapps, Delphine; Cela, Marta; Théobald-Dietrich, Anne; Hendrickson, Tamara; Frugier, Magali

    2016-12-01

    In this review, we examine the so-called OB-fold, a tRNA-binding domain homologous to the bacterial tRNA-binding protein Trbp111. We highlight the ability of OB-fold homologs to bind tRNA species and summarize their distribution in evolution. Nature has capitalized on the advantageous effects acquired when an OB-fold domain binds to tRNA by evolutionarily selecting this domain for fusion to different enzymes. Here, we review our current understanding of how the complexity of OB-fold-containing proteins and enzymes developed to expand their functions, especially in unicellular, pathogenic eukaryotes.

  8. Gender-specific differences in diabetic neuropathy in BTBR ob/ob mice

    PubMed Central

    O’Brien, Phillipe D.; Hur, Junguk; Robell, Nicholas J.; Hayes, John M.; Sakowski, Stacey A.; Feldman, Eva L.

    2015-01-01

    Aims To identify a female mouse model of diabetic peripheral neuropathy (DPN), we characterized DPN in female BTBR ob/ob mice and compared their phenotype to non-diabetic and gender-matched controls. We also identified dysregulated genes and pathways in sciatic nerve (SCN) and dorsal root ganglia (DRG) of female BTBR ob/ob mice to determine potential DPN mechanisms. Methods Terminal neuropathy phenotyping consisted of examining latency to heat stimuli, sciatic motor and sural sensory nerve conduction velocities (NCV), and intraepidermal nerve fiber (IENF) density. For gene expression profiling, DRG and SCN were dissected, RNA was isolated and processed using microarray technology and differentially expressed genes were identified. Results Similar motor and sensory NCV deficits were observed in male and female BTBR ob/ob mice at study termination; however, IENF density was greater in female ob/ob mice than their male counterparts. Male and female ob/ob mice exhibited similar weight gain, hyperglycemia, and hyperinsulinemia compared to non-diabetic controls, although triglycerides were elevated more so in males than in females. Transcriptional profiling of nerve tissue from female mice identified dysregulation of pathways related to inflammation. Conclusions Similar to males, female BTBR ob/ob mice display robust DPN, and pathways related to inflammation are dysregulated in peripheral nerve. PMID:26525588

  9. The Nearest OB Association: Scorpius-Centaurus (Sco OB2)

    NASA Astrophysics Data System (ADS)

    Preibisch, T.; Mamajek, E.

    2008-12-01

    We summarize observational results on the stellar population and star formation history of the Scorpius-Centaurus OB Association (Sco OB2), the nearest region of recent massive star formation. It consists of three subgroups, Upper Scorpius (US), Upper Centaurus-Lupus (UCL), and Lower Centaurus-Crux (LCC) which have ages of about 5, 17, and 16 Myr. While the high- and intermediate mass association members have been studied for several decades, the low-mass population remained mainly unexplored until rather recently. In Upper Scorpius, numerous studies, in particular large multi-object spectroscopic surveys, have recently revealed hundreds of low-mass association members, including dozens of brown dwarfs. The investigation of a large representative sample of association members provided detailed information about the stellar population and the star formation history. The empirical mass function could be established over the full stellar mass range from 0.1 M_⊙ up to 20 M_⊙, and was found to be consistent with recent determinations of the field initial mass function. A narrow range of ages around 5 Myr was found for the low-mass stars, the same age as had previously (and independently) been derived for the high-mass members. This supports earlier indications that the star formation process in US was triggered, and agrees with previous conjectures that the triggering event was a supernova- and wind-driven shock-wave originating from the nearby UCL group. In the older UCL and LCC regions, large numbers of low-mass members have recently been identified among X-ray and proper-motion selected candidates. In both subgroups, low-mass members have also been serendipitously discovered through investigations of X-ray sources in the vicinity of better known regions (primarily the Lupus and TW Hya associations). While both subgroups appear to have mean ages of ˜16 Myr, they both show signs of having substructure. Their star-formation histories may be more complex than that

  10. Chemical evolution of OB associations

    NASA Technical Reports Server (NTRS)

    Schramm, D. N.; Olive, K. A.

    1982-01-01

    It is determined that the existence of Al-26 and Pd-107 in meteorites in the early solar system indicates that our solar system probably formed inside an OB association that had been contaminated by the debris of at least one supernova. In addition to these radioactive tracers, the contamination of the material out of which the solar system formed would have significantly enriched the heavy element composition of the solar system relative to that of the average interstellar medium. It is found that the solar system would be enriched in those isotopes which are produced by the more massive stars, such as O-16, C-12, Ne-20, and some other r-process material. It is proposed that specific isotopic ratios and elemental ratios reflecting these differences would include the Ne-20/Ne-22 ratio, which would be higher in the solar system than in the interstellar medium and the cosmic rays, the C-12/C-13 ratio which would be higher in the solar system than in the interstellar medium, and the oxygen-to-carbon ratio, which would also be higher in the solar system than in the typical interstellar medium.

  11. Impairment of peripheral circadian clocks precedes metabolic abnormalities in ob/ob mice.

    PubMed

    Ando, Hitoshi; Kumazaki, Masafumi; Motosugi, Yuya; Ushijima, Kentarou; Maekawa, Tomohiro; Ishikawa, Eiko; Fujimura, Akio

    2011-04-01

    Recent studies have demonstrated relationships between the dysfunction of circadian clocks and the development of metabolic abnormalities, but the chicken-and-egg question remains unresolved. To address this issue, we investigated the cause-effect relationship in obese, diabetic ob/ob mice. Compared with control C57BL/6J mice, the daily mRNA expression profiles of the clock and clock-controlled genes Clock, Bmal1, Cry1, Per1, Per2, and Dbp were substantially dampened in the liver and adipose tissue, but not the hypothalamic suprachiasmatic nucleus, of 10-wk-old ob/ob mice. Four-week feeding of a low-calorie diet and administration of leptin over a 7-d period attenuated, to a significant and comparable extent, the observed metabolic abnormalities (obesity, hyperglycemia, hyperinsulinemia, and hypercholesterolemia) in the ob/ob mice. However, only leptin treatment improved the impaired peripheral clocks. In addition, clock function, assessed by measuring levels of Per1, Per2, and Dbp mRNA at around peak times, was also reduced in the peripheral tissues of 3-wk-old ob/ob mice without any overt metabolic abnormalities. Collectively these results indicate that the impairment of peripheral clocks in ob/ob mice does not result from metabolic abnormalities but may instead be at least partially caused by leptin deficiency itself. Further studies are needed to clarify how leptin deficiency affects peripheral clocks.

  12. Ablation of ghrelin receptor in leptin-deficient ob/ob mice has paradoxical effects on glucose homeostasis when compared with ablation of ghrelin in ob/ob mice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The orexigenic hormone ghrelin is important in diabetes because it has an inhibitory effect on insulin secretion. Ghrelin ablation in leptin-deficient ob/ob (Ghrelin(-/-):ob/ob) mice increases insulin secretion and improves hyperglycemia. The physiologically relevant ghrelin receptor is the growth ...

  13. Leptin differentially regulates STAT3 activation in the ob/ob mice adipose mesenchymal stem cells

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leptin-deficient genetically obese ob/ob mice exhibit adipocyte hypertrophy and hyperplasia as well as elevated adipose tissue and systemic inflammation. Studies have shown that multipotent stem cells isolated from adult adipose tissue can differentiate into adipocytes ex vivo and thereby contribute...

  14. The MicrOBS study around Taiwan

    NASA Astrophysics Data System (ADS)

    Liang, C.; Lee, C.

    2007-12-01

    Since 2005, we have managed 16 MicrOBS, designed by the French IFREMER, to study the earthquake and crustal structute around Taiwan. The instrument itself is very light (20 kgs) and easy to operate. This OBS has a measuring period up to 2 weeks in the seafloor. We have conducted the works, aiming to get a better understanding of the ¡§marine¡¨ earthquakes, from the in situ small event to the big earthquake. For example, a study of the seismic gaps in the offshore region becomes workable as compare with the time when we only have the land seismological instruments. We have also used this instrument to obtain a detail study of the gas hydrate and free gas zone. Whenever a large seismic source is available, we then conduct the local and regional crustal studies, such as in the Philippine Sea and South China Sea. In the last 3 years, we have directed 285 deployments of MicrOBS around Taiwan. More than 80 per cent of the natural earthquakes in Taiwan (in an average of about 15,000 events of Mm greater than 2 events per year) were occurred in offshore area. Big earthquakes (i.e. Mm greater than 6) are more often happen in the offshore area than that in the onshore region. Therefore, the tools (MicrOBS and OBS) to measure these ¡§marine¡¨ earthquakes become essential to understand the character and origin of crustal dynamics, particularly in the seismogenic zone.

  15. Effects of adrenalectomy on energy balance in obese (ob/ob) mice fed high carbohydrate or high fat diets.

    PubMed

    Grogan, C K; Kim, H K; Romsos, D R

    1987-06-01

    We reported previously that adrenalectomy reduced the energy density of body weight gain (an indicator of proportional gain in lean and fat tissue) and the efficiency of energy retention in obese (ob/ob) mice to values approximating those in lean mice, but that adrenalectomy had much less influence on these parameters in ob/ob mice fed a purified high fat diet. To determine if fat was the exclusive factor in the purified high fat diet that negated effects of adrenalectomy, ob/ob mice were fed a purified high carbohydrate (glucose) diet identical in composition to the high fat diet, except for the fat/carbohydrate ratio. Responses of adrenalectomized ob/ob mice fed the purified high glucose diet from 4 to 7 wk of age mimicked those of mice fed the purified high fat diet, not those of mice fed the high carbohydrate nonpurified diet. Plasma glucose responses to a glucose load in adrenalectomized ob/ob mice paralleled the diet-dependent changes in energy balance. These results demonstrate that diet composition interacts with adrenal secretions to influence energy and glucose metabolism in ob/ob mice; consumption of either a purified high glucose or high fat diet negates the beneficial effects of adrenalectomy on energy and glucose metabolism observed when adrenalectomized ob/ob mice consume a nonpurified diet.

  16. Cordyceps militaris alleviates non-alcoholic fatty liver disease in ob/ob mice

    PubMed Central

    Choi, Ha-Neul; Jang, Yang-Hee; Kim, Min-Joo; Seo, Min Jeong; Kang, Byoung Won; Jeong, Yong Kee

    2014-01-01

    BACKGROUND/OBJECTIVES Non-alcoholic fatty liver disease (NAFLD) is becoming an important public health problem as metabolic syndrome and type 2 diabetes have become epidemic. In this study we investigated the protective effect of Cordyceps militaris (C. militaris) against NAFLD in an obese mouse model. MATERIALS/METHODS Four-week-old male ob/ob mice were fed an AIN-93G diet or a diet containing 1% C. militaris water extract for 10 weeks after 1 week of adaptation. Serum glucose, insulin, free fatty acid (FFA), alanine transaminase (ALT), and proinflammatory cytokines were measured. Hepatic levels of lipids, glutathione (GSH), and lipid peroxide were determined. RESULTS Consumption of C. militaris significantly decreased serum glucose, as well as homeostasis model assessment for insulin resistance (HOMA-IR), in ob/ob mice. In addition to lowering serum FFA levels, C. militaris also significantly decreased hepatic total lipids and triglyceride contents. Serum ALT activities and tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) levels were reduced by C. militaris. Consumption of C. militaris increased hepatic GSH and reduced lipid peroxide levels. CONCLUSIONS These results indicate that C. militaris can exert protective effects against development of NAFLD, partly by reducing inflammatory cytokines and improving hepatic antioxidant status in ob/ob mice. PMID:24741401

  17. Longitudinal evaluation of intramyocellular lipids (IMCLs) in tibialis anterior muscle of ob/ob and ob/+ control mice using a cryogenic surface coil at 9.4 T.

    PubMed

    Ye, Qiong; Danzer, Carsten Friedrich; Fuchs, Alexander; Krek, Wilhelm; Mueggler, Thomas; Baltes, Christof; Rudin, Markus

    2011-12-01

    Insulin resistance is a central feature of type II diabetes and is associated with alterations in skeletal muscle lipid metabolism, which manifest themselves, in part, in increased intramyocellular lipid (IMCL) accumulation. The objective of this study was to assess noninvasively the levels of IMCL longitudinally in the tibialis anterior muscle of Lep(ob) /Lep(ob) (ob/ob) mice, a genetic model of obesity and mild diabetes, and Lep(ob) /+ (ob/+) heterozygous control animals, using (1) H MRS at 9.4 T. The use of a cryogenic surface coil transceiver leads to significant increases in sensitivity. Method implementation included the assessment of the reproducibility and spatial heterogeneity of the IMCL signal and the determination of T(2) relaxation times, as IMCL levels were expressed relative to the total creatine signal, and therefore the signal ratios had to be corrected for differences in T(2) relaxation. IMCL levels were found to be significantly higher in ob/ob mice relative to ob/+ heterozygous control mice that do not develop disease. An increase in IMCL levels was observed for ob/ob mice until weeks 16/17; after this time point, IMCL levels decreased again, reaching final levels that were slightly higher than the initial values. These noninvasively detected alterations in skeletal muscle lipid metabolism in ob/ob mice were accompanied by a transient increase in plasma insulin concentrations. This study indicates that IMCL may be reliably assessed in mouse tibialis anterior muscle using a cryogenic surface coil, implying that (1) H MRS at 9.4 T represents a useful technology for the noninvasive measurement of changes in lipid metabolism in the skeletal muscle that accompany obesity.

  18. Short-term lenalidomide (Revlimid) administration ameliorates cardiomyocyte contractile dysfunction in ob/ob obese mice.

    PubMed

    Li, Linlin; Hua, Yinan; Dong, Maolong; Li, Quan; Smith, Derek T; Yuan, Ming; Jones, Kyla R; Ren, Jun

    2012-11-01

    Lenalidomide is a potent immunomodulatory agent capable of downregulating proinflammatory cytokines such as tumor necrosis factor-α (TNF-α) and upregulating anti-inflammatory cytokines. Lenalidomide has been shown to elicit cardiovascular effects, although its impact on cardiac function remains obscure. This study was designed to examine the effect of lenalidomide on cardiac contractile function in ob/ob obese mice. C57BL lean and ob/ob obese mice were given lenalidomide (50 mg/kg/day, p.o.) for 3 days. Body fat composition was assessed by dual-energy X-ray absorptiometry. Cardiomyocyte contractile and intracellular Ca(2+) properties were evaluated. Expression of TNF-α, interleukin-6 (IL-6), Fas, Fas ligand (FasL), the short-chain fatty acid receptor GPR41, the NFκB regulator IκB, endoplasmic reticulum (ER) stress, the apoptotic protein markers Bax, Bcl-2, caspase-8, tBid, cytosolic cytochrome C, and caspase-12; and the stress signaling molecules p38 and extracellular signal-regulated kinase (ERK) were evaluated by western blot. ob/ob mice displayed elevated serum TNF-α and IL-6 levels, fat composition and glucose intolerance, the effects of which except glucose intolerance and fat composition were attenuated by lenalidomide. Cardiomyocytes from ob/ob mice exhibited depressed peak shortening (PS) and maximal velocity of shortening/relengthening, prolonged time-to-PS and time-to-90% relengthening as well as intracellular Ca(2+) mishandling, which were ablated by lenalidomide. Western blot analysis revealed elevated levels of TNF-α, IL-6, Fas, Bip, Bax, caspase-8, tBid, cleaved caspase-3 caspase-12, cytochrome C, phosphorylation of p38, and ERK in ob/ob mouse hearts, the effects of which with the exception of Bip, Bax, and caspase-12 were alleviated by lenalidomide. Taken together, these data suggest that lenalidomide is protective against obesity-induced cardiomyopathy possibly through antagonism of cytokine/Fas-induced activation of stress signaling and

  19. Alpha-1 adrenoceptors in brown adipose tissue of lean and ob/ob mice

    SciTech Connect

    Behrens-Zaror, G.; Himms-Hagen, J.

    1986-03-01

    Obese (ob/ob) mice have a low capacity to increase thyroxine 5'-deiodinase (T4 5'-D) in brown adipose tissue (BAT) when exposed to cold. This effect is mediated by alpha-1 (A-1) adrenoceptors. The authors objective was to find out whether BAT of the ob/ob mouse has normal A-1 receptors. Saturation analysis of binding of (3H)-WB4101 at 0.05 nM to 10 ..mu..M to crude membrane preparations (100,000 g pellets from Polytron homogenates) using the LIGAND program of Munson and Rodbard, showed two populations of binding sites in BAT of lean (+/+, 11-15 wk old) mice. Acute exposure (12 h, 14/sup 0/C) or acclimation to cold (3 wk, 14/sup 0/C) did not alter affinity or concentration of sites. Displacement with yohimbine and prazosin indicated binding of WB4101 to A-1 receptors. Very young (5 wk) lean (+/.) and obese mice had similar affinity constants (lean 0.13 +/- 0.043 and 34.2 +/- 14.9; obese, 0.12 +/- 0.028 and 20.9 +/- 5.48 nM) and concentrations (lean 22.4 +/- 3.8 and 647 +/- 137; obese, 28.6 +/- 4.6 and 547 +/- 105 fmol/mg protein) of sites. Old (1 yr) mice had high affinity sites similar to those in younger animals (KD lean 0.19 +/- 0.028, obese, 0.25 +/- 0.075; Bmax lean, 60.2 +/- 12.1; obese, 63.1 +/- 13.5 fmol/mg protein). The authors conclude that the ob/ob mouse has normal high affinity A-1 receptors in BAT. Anomalous properties of low affinity binding in old ob/ob mice could not be characterized because of high nonspecific binding. BAT of the ob/ob mouse does not lack A-1 receptors but may have a post-receptor alteration in the A-1 adrenoceptor-mediated response.

  20. Mouth of the Ob River, Russia

    NASA Technical Reports Server (NTRS)

    2002-01-01

    These images from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Terra satellite shows the cause and effect of the large-scale seasonal flooding experienced on rivers throughout Siberia each year. Because many Siberian rivers flow from south to north, they flood regularly in the spring as meltwater from southern latitudes backs up against the still-frozen northern reaches of the rivers.These images show the Ob' River on the western edge of the Central Siberian Plateau. The images from June 20, 2002, show the mouth of the Ob' River (large river at left) where it empties into Kara Sea. In the false-color image, Vegetation appears in bright green, water appears dark blue or black, and ice appears bright blue. The ice is still choking the river's outlet to the sea.The effect of this ice block on the more southern stretches of the river can be seen in the images captured on June 17. In the false-color image, water is black, vegetation is in shades of gold and green, and clouds are pale orange. In the northernmost portion of the Ob' visible in this image (the Ob' runs southeast to northwest in the image), what is normally a fine mesh of braided streams and branches of the river channel has become almost a lake in places. The flood waters have engorged the river to 52 kilometers (32 miles) wide in places. Rivers can back up for hundreds of miles, and cause devastating flooding for towns and villages along the banks. Often, explosives are dropped into ice jams in an effort to free the river and give the flood waters a chance to escape. The spring and summer floods of 2002 have proven to be quite severe and perhaps as many as 100,000 people have been affected across the country. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  1. A very low carbohydrate ketogenic diet improves glucose tolerance in ob/ob mice independently of weight loss.

    PubMed

    Badman, Michael K; Kennedy, Adam R; Adams, Andrew C; Pissios, Pavlos; Maratos-Flier, Eleftheria

    2009-11-01

    In mice of normal weight and with diet-induced obesity, a high-fat, low-carbohydrate ketogenic diet (KD) causes weight loss, reduced circulating glucose and lipids, and dramatic changes in hepatic gene expression. Many of the effects of KD are mediated by fibroblast growth factor 21 (FGF21). We tested the effects of KD feeding on ob/ob mice to determine if metabolic effects would occur in obesity secondarily to leptin deficiency. We evaluated the effect of prolonged KD feeding on weight, energy homeostasis, circulating metabolites, glucose homeostasis, and gene expression. Subsequently, we evaluated the effects of leptin and fasting on FGF21 expression in ob/ob mice. KD feeding of ob/ob mice normalized fasting glycemia and substantially reduced insulin and lipid levels in the absence of weight loss. KD feeding was associated with significant increases in lipid oxidative genes and reduced expression of lipid synthetic genes, including stearoyl-coenzyme A desaturase 1, but no change in expression of inflammatory markers. In chow-fed ob/ob mice, FGF21 mRNA was elevated 10-fold compared with wild-type animals, and no increase from this elevated baseline was seen with KD feeding. Administration of leptin to chow-fed ob/ob mice led to a 24-fold induction of FGF21. Fasting also induced hepatic FGF21 in ob/ob mice. Thus, KD feeding improved ob/ob mouse glucose homeostasis without weight loss or altered caloric intake. These data demonstrate that manipulation of dietary macronutrient composition can lead to marked improvements in metabolic profile of leptin-deficient obese mice in the absence of weight loss.

  2. Flooding of the Ob River, Russia

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A mixture of heavy rainfall, snowmelt, and ice jams in late May and early June of this year caused the Ob River and surrounding tributaries in Western Siberia to overflow their banks. The flooding can be seen in thess image taken on June 16, 2002, by the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument aboard the Terra satellite. Last year, the river flooded farther north. Normally, the river resembles a thin black line, but floods have swollen the river considerably. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  3. Dietary glucose increases plasma insulin and decreases brown adipose tissue thermogenic activity in adrenalectomized ob/ob mice.

    PubMed

    Nei, Y M; Romsos, D R

    1991-09-01

    The purpose of this study was to determine whether consumption of a high glucose diet would increase plasma insulin concentrations and decrease brown adipose tissue metabolism in adrenalectomized ob/ob mice previously fed a high starch diet. Male sham-operated and adrenalectomized ob/ob and lean mice were fed a high starch diet for 12 d, then switched to a high glucose diet for the last 2 or 4 d of the 14- or 16-d feeding trials. Adrenalectomized ob/ob mice consumed 16% more energy and gained 50% more weight without an increase in oxygen consumption when switched from a high starch diet to a high glucose diet. Within 2 d after the switch to the high glucose diet, plasma insulin concentrations increased by 70% without any change in plasma glucose concentrations; brown adipose tissue metabolism, as assessed by GDP binding to brown adipose tissue mitochondria, was decreased by 26% 4 d after the diet switch. Sham-operated ob/ob and lean mice and adrenalectomized lean mice were minimally affected by the switch to the high glucose diet. The increase in plasma insulin concentrations in adrenalectomized ob/ob mice induced by the high glucose diet may contribute to the observed depression in brown adipose tissue metabolism.

  4. Hormone-sensitive lipase deficiency suppresses insulin secretion from pancreatic islets of Lep{sup ob/ob} mice

    SciTech Connect

    Sekiya, Motohiro; Yahagi, Naoya; Tamura, Yoshiaki; Okazaki, Hiroaki; Igarashi, Masaki; Ohta, Keisuke; Takanashi, Mikio; Kumagai, Masayoshi; Takase, Satoru; Nishi, Makiko; Takeuchi, Yoshinori; Izumida, Yoshihiko; Kubota, Midori; Ohashi, Ken; Iizuka, Yoko; Yagyu, Hiroaki; Gotoda, Takanari; Nagai, Ryozo; Shimano, Hitoshi; Yamada, Nobuhiro; and others

    2009-09-25

    It has long been a matter of debate whether the hormone-sensitive lipase (HSL)-mediated lipolysis in pancreatic {beta}-cells can affect insulin secretion through the alteration of lipotoxicity. We generated mice lacking both leptin and HSL (Lep{sup ob/ob}/HSL{sup -/-}) and explored the role of HSL in pancreatic {beta}-cells in the setting of obesity. Lep{sup ob/ob}/HSL{sup -/-} developed elevated blood glucose levels and reduced plasma insulin levels compared with Lep{sup ob/ob}/HSL{sup +/+} in a fed state, while the deficiency of HSL did not affect glucose homeostasis in Lep{sup +/+} background. The deficiency of HSL exacerbated the accumulation of triglycerides in Lep{sup ob/ob} islets, leading to reduced glucose-stimulated insulin secretion. The deficiency of HSL also diminished the islet mass in Lep{sup ob/ob} mice due to decreased cell proliferation. In conclusion, HSL affects insulin secretary capacity especially in the setting of obesity.

  5. A HIPPARCOS Census of the Nearby OB Associations

    NASA Astrophysics Data System (ADS)

    de Zeeuw, P. T.; Hoogerwerf, R.; de Bruijne, J. H. J.; Brown, A. G. A.; Blaauw, A.

    1999-01-01

    A comprehensive census of the stellar content of the OB associations within 1 kpc from the Sun is presented, based on Hipparcos positions, proper motions, and parallaxes. It is a key part of a long-term project to study the formation, structure, and evolution of nearby young stellar groups and related star-forming regions. OB associations are unbound ``moving groups,'' which can be detected kinematically because of their small internal velocity dispersion. The nearby associations have a large extent on the sky, which traditionally has limited astrometric membership determination to bright stars (V<~6 mag), with spectral types earlier than ~B5. The Hipparcos measurements allow a major improvement in this situation. Moving groups are identified in the Hipparcos Catalog by combining de Bruijne's refurbished convergent point method with the ``Spaghetti method'' of Hoogerwerf & Aguilar. Astrometric members are listed for 12 young stellar groups, out to a distance of ~650 pc. These are the three subgroups Upper Scorpius, Upper Centaurus Lupus, and Lower Centaurus Crux of Sco OB2, as well as Vel OB2, Tr 10, Col 121, Per OB2, alpha Persei (Per OB3), Cas-Tau, Lac OB1, Cep OB2, and a new group in Cepheus, designated as Cep OB6. The selection procedure corrects the list of previously known astrometric and photometric B- and A-type members in these groups and identifies many new members, including a significant number of F stars, as well as evolved stars, e.g., the Wolf-Rayet stars gamma^2 Vel (WR 11) in Vel OB2 and EZ CMa (WR 6) in Col 121, and the classical Cepheid delta Cep in Cep OB6. Membership probabilities are given for all selected stars. Monte Carlo simulations are used to estimate the expected number of interloper field stars. In the nearest associations, notably in Sco OB2, the later-type members include T Tauri objects and other stars in the final pre-main-sequence phase. This provides a firm link between the classical high-mass stellar content and ongoing low

  6. Automated identification of OB associations in M31

    NASA Technical Reports Server (NTRS)

    Magnier, Eugene A.; Battinelli, Paolo; Lewin, Walter H. G.; Haiman, Zoltan; Paradijs, Jan Van; Hasinger, Guenther; Pietsch, Wolfgang; Supper, Rodrigo; Truemper, Joachim

    1993-01-01

    A new identification of OB associations in M31 has been performed using the Path Linkage Criterion (PLC) technique of Battinelli (1991). We found 174 associations with a very small contamination (less than 5%) by random clumps of stars. The expected total number and average size of OB associations in the region of M 31 covered by our data set (Magnier et al. 1992) are approximately 280 and approximately 90 pc, respectively. M31 associations therefore have sizes similar to those of OB associations observed in nearby galaxies, so that we can consider them to be classical OB associations. This list of OB associations will be used for the study of the spatial distribution of OB associations and their correlation with other objects. Taking into account the fact that we do not cover the entire disk of M31, we extrapolate a total number of association in M31 of approximately 420.

  7. Multicolor Polarization Study of ARA OB1

    NASA Astrophysics Data System (ADS)

    Waldhausen, Silvia; Martínez, Ruben E.; Feinstein, Carlos

    1999-06-01

    We present the results of a multicolor polarimetric study of stars in the association Ara OB1. Several objects belonging to the clusters NGC 6204, 6193, and 6167 and the local field were observed as part of a global study of the region. The polarimetry shows that the orientation of the polarimetric vectors of each star is very similar within each cluster. The average values are 35.5d+/-15.1d and 52.2d+/-16 deg for NGC 6204 and 6193, respectively. An average value of 106.5d+/-9.9d is found for NGC 6167, but the angle distribution is asymmetric, and a second component can be fitted to the angle histogram (P.A.~120.8d+/-11.6d), showing a behavior not observed in NGC 6204 and 6193. So, we suggest that some of the observed stars perhaps belong to another stars grouping, located behind NGC 6167 and between a dust layer with a different orientation of the grains. The large difference in the polarization angle between NGC 6167 and the other two clusters could also be explained because NGC 6167 is supposed to be at the center of a gas-expanding structure and it is possible that this cluster was the origin of the star formation process in the Ara OB1 association, triggered by stellar winds or supernova explosions.

  8. Leptin Administration Downregulates the Increased Expression Levels of Genes Related to Oxidative Stress and Inflammation in the Skeletal Muscle of ob/ob Mice

    PubMed Central

    Sáinz, Neira; Rodríguez, Amaia; Catalán, Victoria; Becerril, Sara; Ramírez, Beatriz; Gómez-Ambrosi, Javier; Frühbeck, Gema

    2010-01-01

    Obese leptin-deficient ob/ob mice exhibit a low-grade chronic inflammation together with a low muscle mass. Our aim was to analyze the changes in muscle expression levels of genes related to oxidative stress and inflammatory responses in leptin deficiency and to identify the effect of in vivo leptin administration. Ob/ob mice were divided in three groups as follows: control ob/ob, leptin-treated ob/ob (1 mg/kg/d) and leptin pair-fed ob/ob mice. Gastrocnemius weight was lower in control ob/ob than in wild type mice (P < .01) exhibiting an increase after leptin treatment compared to control and pair-fed (P < .01) ob/ob animals. Thiobarbituric acid reactive substances, markers of oxidative stress, were higher in serum (P < .01) and gastrocnemius (P = .05) of control ob/ob than in wild type mice and were significantly decreased (P < .01) by leptin treatment. Leptin deficiency altered the expression of 1,546 genes, while leptin treatment modified the regulation of 1,127 genes with 86 of them being involved in oxidative stress, immune defense and inflammatory response. Leptin administration decreased the high expression of Crybb1, Hspb3, Hspb7, Mt4, Cat, Rbm9, Serpinc1 and Serpinb1a observed in control ob/ob mice, indicating that it improves inflammation and muscle loss. PMID:20671928

  9. Localization of the human OB gene (OBS) to chromosome 7q32 by fluorescence in situ hybridization

    SciTech Connect

    Geffroy, S.; Duban, B.; Martinville, B. de

    1995-08-10

    An important gene involved in the pathogenesis of obesity is the product of the human homologue of the murine obese gene (gene symbol OBS). Using fluorescence in situ hybridization (FISH), we have localized the human OB gene to human chromosome 7, specifically to region 7q32.1. The FISH data of human OBS provide a gene-associated marker for genetic mapping. 8 refs., 1 fig.

  10. The origin of OB runaway stars.

    PubMed

    Fujii, Michiko S; Portegies Zwart, Simon

    2011-12-09

    About 20% of all massive stars in the Milky Way have unusually high velocities, the origin of which has puzzled astronomers for half a century. We argue that these velocities originate from strong gravitational interactions between single stars and binaries in the centers of star clusters. The ejecting binary forms naturally during the collapse of a young (≤1 million years old) star cluster. This model replicates the key characteristics of OB runaways in our galaxy, and it explains the presence of runaway stars of ≥100 solar masses (M(⊙)) around young star clusters, such as R136 and Westerlund 2. The high proportion and the distributions in mass and velocity of runaways in the Milky Way are reproduced if the majority of massive stars are born in dense and relatively low-mass (5000 to 10,000 M(⊙)) clusters.

  11. Open clusters in Auriga OB2

    NASA Astrophysics Data System (ADS)

    Marco, Amparo; Negueruela, Ignacio

    2016-06-01

    We study the area around the H II region Sh 2-234, including the young open cluster Stock 8, to investigate the extent and definition of the association Aur OB2 and the possible role of triggering in massive cluster formation. We obtained Strömgren and J, H, KS photometry for Stock 8 and Strömgren photometry for two other cluster candidates in the area, which we confirm as young open clusters and name Alicante 11 and Alicante 12. We took spectroscopy of ˜33 early-type stars in the area, including the brightest cluster members. We calculate a common distance of 2.80^{+0.27}_{-0.24} kpc for the three open clusters and surrounding association. We derive an age 4-6 Ma for Stock 8, and do not find a significantly different age for the other clusters or the association. The star LS V +34°23, with spectral type O8 II(f), is likely the main source of ionization of Sh 2-234. We observe an important population of pre-main-sequence stars, some of them with discs, associated with the B-type members lying on the main sequence. We interpret the region as an area of recent star formation with some residual and very localized ongoing star formation. We do not find evidence for sequential star formation on a large scale. The classical definition of Aur OB2 has to be reconsidered, because its two main open clusters, Stock 8 and NGC 1893, are not at the same distance. Stock 8 is probably located in the Perseus arm, but other nearby H II regions whose distances also place them in this arm show quite different distances and radial velocities and, therefore, are not connected.

  12. Flooding of the Ob and Irtysh Rivers, Russia

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This pair of true- and false-color images shows flooding along the Ob' (large east-west running river) and Irtysh (southern tributary of the Ob') on July 7, 2002. In the false-color image, land surfaces are orange-gold and flood waters are black or dark blue. Fires are marked with red dots in both images. Rivers

  13. Effect of Leptin Replacement on PCSK9 in ob/ob Mice and Female Lipodystrophic Patients.

    PubMed

    Levenson, Amy E; Haas, Mary E; Miao, Ji; Brown, Rebecca J; de Ferranti, Sarah D; Muniyappa, Ranganath; Biddinger, Sudha B

    2016-04-01

    Leptin treatment has beneficial effects on plasma lipids in patients with lipodystrophy, but the underlying mechanism is unknown. Proprotein convertase subtilisin/kexin type 9 (PCSK9) decreases low-density lipoprotein (LDL) clearance, promotes hypercholesterolemia, and has recently emerged as a novel therapeutic target. To determine the effect of leptin on PCSK9, we treated male and female ob/ob mice with leptin for 4 days via sc osmotic pumps (∼24 μg/d). Leptin reduced body weight and food intake in all mice, but the effects of leptin on plasma PCSK9 and lipids differed markedly between the sexes. In male mice, leptin suppressed PCSK9 but had no effect on plasma triglycerides or cholesterol. In female mice, leptin suppressed plasma triglycerides and cholesterol but had no effect on plasma PCSK9. In parallel, we treated female lipodystrophic patients (8 females, ages 5-23 y) with sc metreleptin injections (∼4.4 mg/d) for 4-6 months. In this case, leptin reduced plasma PCSK9 by 26% (298 ± 109 vs 221 ± 102 ng/mL; n = 8; P = .008), and the change in PCSK9 was correlated with a decrease in LDL cholesterol (r(2) = 0.564, P = .03). In summary, in leptin-deficient ob/ob mice, the effects of leptin on PCSK9 and plasma lipids appeared to be independent of one another and strongly modified by sex. On the other hand, in lipodystrophic females, leptin treatment reduced plasma PCSK9 in parallel with LDL cholesterol.

  14. Odor-Induced Neuronal Rhythms in the Olfactory Bulb Are Profoundly Modified in ob/ob Obese Mice

    PubMed Central

    Chelminski, Yan; Magnan, Christophe; Luquet, Serge H.; Everard, Amandine; Meunier, Nicolas; Gurden, Hirac; Martin, Claire

    2017-01-01

    Leptin, the product of the Ob(Lep) gene, is a peptide hormone that plays a major role in maintaining the balance between food intake and energy expenditure. In the brain, leptin receptors are expressed by hypothalamic cells but also in the olfactory bulb, the first central structure coding for odors, suggesting a precise function of this hormone in odor-evoked activities. Although olfaction plays a key role in feeding behavior, the ability of the olfactory bulb to integrate the energy-related signal leptin is still missing. Therefore, we studied the fate of odor-induced activity in the olfactory bulb in the genetic context of leptin deficiency using the obese ob/ob mice. By means of an odor discrimination task with concomitant local field potential recordings, we showed that ob/ob mice perform better than wild-type (WT) mice in the early stage of the task. This behavioral gain of function was associated in parallel with profound changes in neuronal oscillations in the olfactory bulb. The distribution of the peaks in the gamma frequency range was shifted toward higher frequencies in ob/ob mice compared to WT mice before learning. More notably, beta oscillatory activity, which has been shown previously to be correlated with olfactory discrimination learning, was longer and stronger in expert ob/ob mice after learning. Since oscillations in the olfactory bulb emerge from mitral to granule cell interactions, our results suggest that cellular dynamics in the olfactory bulb are deeply modified in ob/ob mice in the context of olfactory learning. PMID:28154537

  15. Photometry of stars in the Cas OB5 Associations

    NASA Astrophysics Data System (ADS)

    Tanriver, Mehmet; Keskin, Ahmet

    2016-07-01

    OB associations are a grouping of very young associations, contain 10-100 very hot massive stars, spectral types O and B. Also, the OB associations contain low and intermediate mass stars, too. Association members are believed to form within the same small volume inside a giant molecular cloud. Once the surrounding dust and gas is blown away, the remaining stars become not tied up and begin to drift separately. It is believed that the majority of all stars in the Milky Way were formed in OB associations. O type stars are short-lived, and will be at an end as supernovae after roundly a million years. OB associations are generally only a few million years in age or less. In this study, the photometry of UU Cas and field star which been Cas OB5 association member was carried out. Light curves and color diagrams are given in the study.

  16. Anti-obesity and anti-diabetic effects of a standardized potato extract in ob/ob mice

    PubMed Central

    KU, SAE KWANG; SUNG, SOO HYUN; CHOUNG, JAI JUN; CHOI, JAE-SUK; SHIN, YONG KOOK; KIM, JOO WAN

    2016-01-01

    The potato (Solanum tuberosum) has been cultivated globally for food for millenia. Potato contains proteinase inhibitor II, which catalyzes the release of cholecystokinin (CCK), leading to delayed gastric emptying in humans. The present study investigated the anti-obesity effects of Slendesta™ Potato Extract (SLD), a standardized potato extract containing 5% proteinase inhibitor II, in the ob/ob obese mice. Three doses of SLD (50, 150 or 300 mg/kg) were orally administered to ob/ob mice once a day for 28 days, whereas control mice were administered distilled water. Four weeks after SLD treatment, the changes in body weight, food consumption, epididymal fat weight, serum chemistry, insulin, leptin and adiponectin contents, and fat histopathology were determined and compared with ob/ob mice treated with 750 mg/kg conjugate linoleic acid. As a result of SLD treatment in the obese mice, body weight, food consumption, epididymal fat, serum biochemistry, histomorphological changes of fat and pancreas were significantly and dose-dependently decreased compared with ob/ob control mice. These obesity and type 2 diabetes associated alterations were significantly inhibited after SLD treatment for 28 days. Thus, the present results indicate that SLD has potential as an alternative therapeutic agent for obesity. PMID:27347062

  17. Leptin Increases Striatal Dopamine D2 Receptor Binding in Leptin-Deficient Obese (ob/ob) Mice

    SciTech Connect

    Pfaffly, J.; Michaelides, M.; Wang, G-J.; Pessin, J.E.; Volkow, N.D.; Thanos, P.K.

    2010-06-01

    Peripheral and central leptin administration have been shown to mediate central dopamine (DA) signaling. Leptin-receptor deficient rodents show decreased DA D2 receptor (D2R) binding in striatum and unique DA profiles compared to controls. Leptin-deficient mice show increased DA activity in reward-related brain regions. The objective of this study was to examine whether basal D2R-binding differences contribute to the phenotypic behaviors of leptin-deficient ob/ob mice, and whether D2R binding is altered in response to peripheral leptin treatment in these mice. Leptin decreased body weight, food intake, and plasma insulin concentration in ob/ob mice but not in wild-type mice. Basal striatal D2R binding (measured with autoradiography [{sup 3}H] spiperone) did not differ between ob/ob and wild-type mice but the response to leptin did. In wild-type mice, leptin decreased striatal D2R binding, whereas, in ob/ob mice, leptin increased D2R binding. Our findings provide further evidence that leptin modulates D2R expression in striatum and that these effects are genotype/phenotype dependent.

  18. OB protein binds specifically to the choroid plexus of mice and rats.

    PubMed

    Devos, R; Richards, J G; Campfield, L A; Tartaglia, L A; Guisez, Y; van der Heyden, J; Travernier, J; Plaetinck, G; Burn, P

    1996-05-28

    Binding studies were conducted to identify the anatomical location of brain target sites for OB protein, the ob gene product. 125I-labeled recombinant mouse OB protein or alkaline phosphatase-OB fusion proteins were used for in vitro and in vivo binding studies. Coronal brain sections or fresh tissue from lean, obese ob/ob, and obese db/db mice as well as lean and obese Zucker rats were probed to identify potential central OB protein-binding sites. We report here that recombinant OB protein binds specifically to the choroid plexus. The binding of OB protein (either radiolabeled or the alkaline phosphatase-OB fusion protein) and its displacement by unlabeled OB protein was similar in lean, obese ob/ob, and obese db/db mice as well as lean and obese Zucker rats. These findings suggest that OB protein binds with high affinity to a specific receptor in the choroid plexus. After binding to the choroid plexus receptor, OB protein may then be transported across the blood-brain barrier into the cerebrospinal fluid. Alternatively, binding of OB protein to a specific receptor in the choroid plexus may activate afferent neural inputs to the neural network that regulates feeding behavior and energy balance or may result in the clearance or degradation of OB protein. The identification of the choroid plexus as a brain binding site for OB protein will provide the basis for the construction of expression libraries and facilitate the rapid cloning of the choroid plexus OB receptor.

  19. New OBS network deployment offshore Ireland

    NASA Astrophysics Data System (ADS)

    Le Pape, Florian; Bean, Chris; Craig, David; Jousset, Philippe; Horan, Clare; Hogg, Colin; Donne, Sarah; McCann, Hannah; Möllhoff, Martin; Kirk, Henning; Ploetz, Aline

    2016-04-01

    With the presence of the stormy NE Atlantic, Ireland is ideally located to investigate further our understanding of ocean generated microseisms and use noise correlation methods to develop seismic imaging in marine environments as well as time-lapse monitoring. In order to study the microseismic activity offshore Ireland, 10 Broad Band Ocean Bottom Seismographs (OBSs) units including hydrophones have been deployed in January 2016 across the shelf offshore Donegal and out into the Rockall Trough. This survey represents the first Broadband passive study in this part of the NE Atlantic. The instruments will be recovered in August 2016 providing 8 months worth of data to study microseisms but also the offshore seismic activity in the area. One of the main goal of the survey is to investigate the spatial and temporal distributions of dominant microseism source regions, close to the microseism sources. Additionally we will study the coupling of seismic and acoustic signals at the sea bed and its evolution in both the deep water and continental shelf areas. Furthermore, the survey also aims to investigate further the relationship between sea state conditions (e.g. wave height, period), seafloor pressure variations and seismic data recorded on both land and seafloor. Finally, the deployed OBS network is also the first ever attempt to closely monitor local offshore earthquakes in Ireland. Ireland seismicity although relatively low can reduce slope stability and poses the possibility of triggering large offshore landslides and local tsunamis.

  20. A deep PSPC obervation of the Cyg OB2 association

    NASA Technical Reports Server (NTRS)

    Waldron, Wayne

    1995-01-01

    The Cyg OB2 Association contains six of the fifteen most luminous stars in the Galaxy as well as the most luminous and most heavily reddened Galactic star, Cyg OB2 #12. In addition, the association contains a number of Wolf-Rayet stars, at least one early-type binary (Cyg OB2 #5), and a trapezium-like system (Cyg OB2 #8). Though not physically associated with the association, the X-ray source Cyg X-3 lies within a half degree of the center of the association. The association is a known source of X-rays. The X-ray emission from this region includes a contribution from Cyg X-3, as well as coronal emission from OB stars and hot diffuse gas. The region was extensively sampled by the HEAO-2 IPC (136 ks, which includes a single pointing of 57 ks on the central region of the association). A 3.6 ks PSPC observation of this region was obtained in the AO1 pointing phase. In addition, the four brightest OB stars (Cyg OB2 #5, #8A, #9, and #12) have been extensively monitored with the VLA. These stars show evidence of strong radio variability, and nonthermal radio emission characteristics. Several of these radio observations were taken within about a month of an IPC observation, and the two PSPC observations. We obtained a 19.5 ks exposure of the Cyg OB2 Association using the ROSAT PSPC instrument. Scientific tasks included: (1) extracting the PSPC spectral distributions of the brightest OB stars; (2) comparing the 19.5 ks spectral data with the 3.6 ks spectral data; (3) investigating the long term X-ray variability (15 years); and (4) comparing the X-ray and radio variability.

  1. TCP over OBS - fixed-point load and loss.

    PubMed

    Cameron, Craig; Le Vu, Hai; Choi, Jung; Bilgrami, Syed; Zukerman, Moshe; Kang, Minho

    2005-11-14

    The sending rate of commonly used TCP protocols is tightly coupled to packet loss within the network: a high rate of packet loss will cause a sender to slow down, thereby reducing the network load and decreasing subsequent packet loss rates. In this paper, we combine a widely verified source rate TCP model with an Optical Burst Switching (OBS) loss model, to find fixed-point input loads and loss rates for an OBS link carrying TCP traffic. In doing so, we show that if OBS networks are to be efficiently used to carry TCP traffic, many wavelengths with full wavelength conversion are required.

  2. Additional red and reddened stars in Cyg OB2 association

    NASA Technical Reports Server (NTRS)

    Parthasarathy, M.; Jain, S. K.

    1989-01-01

    Several new red and reddened stars are detected in the most heavily reddened associations Cyg OB2. About 47 IRAS sources are detected in Cyg OB2. Their flux distributions, and colors, suggest that they are young stellar objects embedded in dust envelopes or disks (some of them may be proto stars) and are most likely members of the Cyg OB2 association. The large values of the flux ratio L sub IR/L sub VIS suggests that the central objects are obscured because of very large extinction.

  3. The interstellar medium in the ARA OB1 field

    NASA Astrophysics Data System (ADS)

    Rizzo, J. R.; Bajaja, E.

    1994-09-01

    We report here the results of a detailed study of two surveys of H I, at lambda = 21 cm, in the field of the stellar association Ara OB1. Subtracting the background with a procedure developed here, we were able to identify two H I shell-like features, at roughly the same position but at different velocities, whose parameters were determined. On the basis of their kinematical distances, two concentrations of OB stars (one at 1400 pc, belonging to Ara OB1, and another at 2500 pc) might be the progenitors of these shells. The nearest H I shell may have triggered a process of star formation.

  4. New Results on the Nearest OB Association: Sco-Cen (Sco OB2)

    NASA Astrophysics Data System (ADS)

    Mamajek, Eric E.

    2013-01-01

    The Scorpius-Centaurus OB association (Sco OB2) is the nearest site of recent massive star formation to the Sun. The primary stellar groups in the Sco-Cen complex (including OB subgroups Upper Sco, Upper Cen Lup, and Lower Cen Cru, the neighboring molecular cloud complexes Lup, Cha, CrA, Oph, and dispersed young groups Eta Cha, Epsilon Cha, TW Hya, and Beta Pic) have been participants in a complex episode of stellar birth (and some stellar death) over the past ~20 Myr. Here I summarize some recent results on the Sco-Cen complex from the U. Rochester group: (1) isochronal analysis of the HR diagram positions for >1 Msun stars in the Upper Scorpius subgroup shows it to be twice as old as previously thought (11 Myr vs. 5 Myr), (2) analysis of high resolution optical echelle spectra show that the subgroups are approximately solar in composition, (3) surveys for lower mass members are showing that the complex shows more substructure than previously recognized, including at least one new subgroup ("Lower Sco"), and the velocity and age data for the nearest OB subgroup Lower Cen Cru argue for a bifurcation into a younger 10 Myr) southern part ("Crux") and an older 20 Myr) northern part ("Lower Centaurus"), (4) an eclipsing, multi-ring dust disk system was serendipitously discovered in the SuperWASP and ASAS light curve for the newly discovered K5-type Sco-Cen member 1SWASP J140747.93-394542.6. With regard to some recent results by other investigators, we find that (1) attempts by some authors to subsume the Sco-Cen subgroups into a single sample of a single age are unnecessarily mixing samples with a wide range in ages, and (2) I have been unable to replicate the expansion age determinations claimed by some investigators for the TW Hya and Beta Pic groups (both purported to have expansion ages of 8 and 12 Myr, respectively), which have been used by some investigators to independently age-date the Sco-Cen subgroups. We acknowledge support from NSF grant AST-1008908 and the

  5. BOREAS TF-9 SSA-OBS Branch Level Flux Data

    NASA Technical Reports Server (NTRS)

    Rayment, Mark B.; Jarvis, Paul G.; Hall, Forrest G. (Editor); Huemmrich, Karl (Editor)

    2000-01-01

    The BOREAS TF-9 team collected data that describe carbon dioxide and water vapor fluxes from foliage at the BOREAS SSA-OBS site from 07-April through 23-November-1996. The data are available in tabular ASCII files.

  6. obs4MIPS: Satellite Datasets for Model Evaluation

    NASA Astrophysics Data System (ADS)

    Ferraro, R.; Waliser, D. E.; Gleckler, P. J.

    2013-12-01

    This poster will review the current status of the obs4MIPs project, whose purpose is to provide a limited collection of well-established and documented datasets for comparison with Earth system models. These datasets have been reformatted to correspond with the CMIP5 model output requirements, and include technical documentation specifically targeted for their use in model output evaluation. There are currently over 50 datasets containing observations that directly correspond to CMIP5 model output variables. We will review the rational and requirements for obs4MIPs contributions, and provide summary information of the current obs4MIPs holdings on the Earth System Grid Federation. We will also provide some usage statistics, an update on governance for the obs4MIPs project, and plans for supporting CMIP6.

  7. Flooding of the Ob and Irtysh Rivers, Russia

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This pair of true- and false-color images shows flooding along the Ob' (large east-west running river) and Irtysh (southern tributary of the Ob') on July 7, 2002. In the false-color image, land surfaces are orange-gold and flood waters are black or dark blue. Fires are marked with red dots in both images. Rivers Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  8. Quantifying the Components of the Field OB Star Population

    NASA Astrophysics Data System (ADS)

    Chen, Xinyi; Oey, M. S.; Lamb, Joel B.; Kushner, Cole

    2016-01-01

    Massive stars have long been thought to form in clusters. However, recent observations suggest some massive stars form in extremely sparse environments. Could these massive stars form alone? Clarifying the nature of field OB stars is central to this question. Defining these as OB stars that are isolated from other OB stars, the field comprises three distinct populations: "tip-of-the-iceberg stars", which are in small, but normal, clusters that only have one OB star; runaway stars; and any stars that form in situ in the field. The relative frequencies of each category are unknown. To study the population and obtain estimates of the frequencies, we examine 134 field OB stars from the Runaways and Isolated O-Type Star Spectroscopic Survey of the SMC (RIOTS4; Lamb et al. 2015) in the bar region of the Small Magellanic Cloud. These stars are at least 28 pc in projection away from other OB stars. We use OGLE-III (Udalski et al. 2008) I-band images to search for small, potential clusters around our target stars, using friends-of-friends and nearest-neighbor algorithms. We estimate the relative frequencies of tip-of-the-iceberg stars and isolated stars, some of which may have formed in situ. Thanks to Radek Poleski for help with the OGLE-III database. This work was supported by the NSF grants AST-0907758 and AST-1514838.

  9. Tumour necrosis factor-α inhibition with lenalidomide alleviates tissue oxidative injury and apoptosis in ob/ob obese mice.

    PubMed

    Zhu, Xiaoling; Jiang, Shasha; Hu, Nan; Luo, Fuling; Dong, Hailong; Kang, Yu-Ming; Jones, Kyla R; Zou, Yunzeng; Xiong, Lize; Ren, Jun

    2014-07-01

    Lenalidomide (Revlimid; Selleck Chemicals, Houston, TX, USA), an analogue of thalidomide, possesses potent cytokine modulatory capacity through inhibition of cytokines such as tumour necrosis factor (TNF)-α, a cytokine pivotal for the onset and development of complications in obesity and diabetes mellitus. The present study was designed to evaluate the effect of lenalidomide on oxidative stress, protein and DNA damage in multiple organs in an ob/ob murine model of obesity. To this end, C57BL/6 lean and ob/ob obese mice were administered lenalidomide (50 mg/kg per day, p.o.) for 5 days. Oxidative stress, protein and DNA damage were assessed using the conversion of reduced glutathione (GSH) to oxidized glutathione (GSSG), carbonyl formation and Comet assay, respectively. Apoptosis was evaluated using caspase 3 activity, and levels of Bax, Bcl-2, Bip, caspase 8, caspase 9 and TNF-α were assessed using western blot analysis. Lenalidomide treatment did not affect glucose clearance in lean or ob/ob mice. Obese mice exhibited a reduced GSH/GSSG ratio in the liver, gastrocnemius skeletal muscle and small intestine, as well as enhanced protein carbonyl formation, DNA damage and caspase 3 activity in the liver, kidney, skeletal muscle and intestine; these effects were alleviated by lenalidomide, with the exception of obesity-associated DNA damage in the liver and kidney. Western blot analysis revealed elevated TNF-α, Bax, Bcl-2, Bip, caspase 8 and caspase 9 in ob/ob mice with various degrees of reversal by lenalidomide treatment. Together, these data indicate that lenalidomide protects against obesity-induced tissue injury and protein damage, possibly in association with antagonism of cytokine production and cytokine-induced apoptosis and oxidative stress.

  10. Modulation of hepatic microsomal triglyceride transfer protein (MTP) induced by S-nitroso-N-acetylcysteine in ob/ob mice.

    PubMed

    Oliveira, Claudia P M S; Alves, Venâncio A F; Lima, Vicência M R; Stefano, José Tadeu; Debbas, Victor; Sá, Sandra Valéria; Wakamatsu, Alda; Corrêa-Giannella, Maria Lúcia; de Mello, Evandro Sobroza; Havaki, Sofia; Tiniakos, Dina G; Marinos, Evangelos; de Oliveira, Marcelo G; Giannella-Neto, Daniel; Laurindo, Francisco R; Caldwell, Stephen; Carrilho, Flair J

    2007-07-15

    We evaluated the effects of a potent NO donor, S-nitroso-N-acetylcysteine (SNAC), on microsomal triglyceride transfer protein (MTP) expression in ob/ob mice. NAFLD was induced in male ob/ob mice using a methionine-choline deficient diet (MCD) concomitantly with oral SNAC fed solution (n=5) or vehicle (control; n=5) by gavage daily for 4 weeks. Livers were collected for histology and for assessing MTP by RT-qPCR, Western blot, immunohistochemistry and immunogold electron microscopy analyses. Histological analysis showed diffuse macro and microvesicular steatosis, moderate hepatocellular ballooning and moderate inflammatory infiltrate in ob/ob mice fed the MCD diet. With SNAC, mice showed a marked reduction in liver steatosis (p<0.01), in parenchymal inflammation (p=0.02) and in MTP protein immunoexpression in zone III (p=0.05). Moreover, SNAC caused reduction of MTP protein in Western blot analysis (p<0.05). In contrast, MTP mRNA content was significantly higher (p<0.05) in mice receiving SNAC. Immuno-electron microscopy showed MTP localized in the rough endoplasmic reticulum of hepatocytes in both treated and untreated groups. However with SNAC treatment, MTP was also observed surrounding fat globules. Histological improvement mediated by a nitric oxide donor is associated with significantly altered expression and distribution of MTP in this animal model of fatty liver disease. Further studies are in progress to examine possible mechanisms and to develop SNAC as a possible therapy for human fatty liver disease.

  11. Carnosine Attenuates the Development of both Type 2 Diabetes and Diabetic Nephropathy in BTBR ob/ob Mice

    PubMed Central

    Albrecht, Thomas; Schilperoort, Maaike; Zhang, Shiqi; Braun, Jana D.; Qiu, Jiedong; Rodriguez, Angelica; Pastene, Diego O.; Krämer, Bernhard K.; Köppel, Hannes; Baelde, Hans; de Heer, Emile; Anna Altomare, Alessandra; Regazzoni, Luca; Denisi, Alessandra; Aldini, Giancarlo; van den Born, Jacob; Yard, Benito A.; Hauske, Sibylle J.

    2017-01-01

    We previously demonstrated that polymorphisms in the carnosinase-1 gene (CNDP1) determine the risk of nephropathy in type 2 diabetic patients. Carnosine, the substrate of the enzyme encoded by this gene, is considered renoprotective and could possibly be used to treat diabetic nephropathy (DN). In this study, we examined the effect of carnosine treatment in vivo in BTBR (Black and Tan, BRachyuric) ob/ob mice, a type 2 diabetes model which develops a phenotype that closely resembles advanced human DN. Treatment of BTBR ob/ob mice with 4 mM carnosine for 18 weeks reduced plasma glucose and HbA1c, concomitant with elevated insulin and C-peptide levels. Also, albuminuria and kidney weights were reduced in carnosine-treated mice, which showed less glomerular hypertrophy due to a decrease in the surface area of Bowman’s capsule and space. Carnosine treatment restored the glomerular ultrastructure without affecting podocyte number, resulted in a modified molecular composition of the expanded mesangial matrix and led to the formation of carnosine-acrolein adducts. Our results demonstrate that treatment with carnosine improves glucose metabolism, albuminuria and pathology in BTBR ob/ob mice. Hence, carnosine could be a novel therapeutic strategy to treat patients with DN and/or be used to prevent DN in patients with diabetes. PMID:28281693

  12. Gender-Specific Metabolomic Profiling of Obesity in Leptin-Deficient ob/ob Mice by 1H NMR Spectroscopy

    PubMed Central

    Kim, Sang-Woo; Jung, Youngae; Bae, Hyun-Whee; Lee, Daeyoup; Park, Sung Goo; Lee, Chul-Ho; Hwang, Geum-Sook; Chi, Seung-Wook

    2013-01-01

    Despite the numerous metabolic studies on obesity, gender bias in obesity has rarely been investigated. Here, we report the metabolomic analysis of obesity by using leptin-deficient ob/ob mice based on the gender. Metabolomic analyses of urine and serum from ob/ob mice compared with those from C57BL/6J lean mice, based on the 1H NMR spectroscopy in combination with multivariate statistical analysis, revealed clear metabolic differences between obese and lean mice. We also identified 48 urine and 22 serum metabolites that were statistically significantly altered in obese mice compared to lean controls. These metabolites are involved in amino acid metabolism (leucine, alanine, ariginine, lysine, and methionine), tricarbocylic acid cycle and glucose metabolism (pyruvate, citrate, glycolate, acetoacetate, and acetone), lipid metabolism (cholesterol and carnitine), creatine metabolism (creatine and creatinine), and gut-microbiome-derived metabolism (choline, TMAO, hippurate, p-cresol, isobutyrate, 2-hydroxyisobutyrate, methylamine, and trigonelline). Notably, our metabolomic studies showed distinct gender variations. The obese male mice metabolism was specifically associated with insulin signaling, whereas the obese female mice metabolism was associated with lipid metabolism. Taken together, our study identifies the biomarker signature for obesity in ob/ob mice and provides biochemical insights into the metabolic alteration in obesity based on gender. PMID:24098417

  13. e-MERLIN 21 cm constraints on the mass-loss rates of OB stars in Cyg OB2

    NASA Astrophysics Data System (ADS)

    Morford, J. C.; Fenech, D. M.; Prinja, R. K.; Blomme, R.; Yates, J. A.

    2016-11-01

    We present e-MERLIN 21 cm (L-band) observations of single luminous OB stars in the Cygnus OB2 association, from the Cyg OB2 Radio Survey Legacy programme. The radio observations potentially offer the most straightforward, least model-dependent, determinations of mass-loss rates, and can be used to help resolve current discrepancies in mass-loss rates via clumped and structured hot star winds. We report here that the 21 cm flux densities of O3 to O6 supergiant and giant stars are less than ˜70 μJy. These fluxes may be translated to `smooth' wind mass-loss upper limits of ˜4.4-4.8 × 10-6 M⊙ yr -1 for O3 supergiants and ≲2.9 × 10-6 M⊙ yr -1 for B0 to B1 supergiants. The first ever resolved 21 cm detections of the hypergiant (and luminous blue variable candidate) Cyg OB2 #12 are discussed; for multiple observations separated by 14 d, we detect an ˜69 per cent increase in its flux density. Our constraints on the upper limits for the mass-loss rates of evolved OB stars in Cyg OB2 support the model that the inner wind region close to the stellar surface (where Hα forms) is more clumped than the very extended geometric region sampled by our radio observations.

  14. Stromgren and H beta photometry of OB associations and open clusters. I - ARA OB1

    NASA Astrophysics Data System (ADS)

    Kaltcheva, Nadia T.; Georgiev, Leonid N.

    1992-11-01

    Stromgren and H beta photometry of 38 stars in the field of Ara OB1 is presented. The excesses, the absolute magnitudes and the temperatures of the stars have been obtained. The masses and the ages are also estimated, based on the models of Maeder and Meynet. Two different groups have been distinguished by their space locations at V0 - MV = 10.23 and 12.01 mag (assuming a normal extinction law). The more distant group is younger and more massive. The magnitude and the excess of the WR star MR62 point to its probable membership of this group. There are good reasons to suspect a value of the total-to-selective absorption ratio that is greater than the normal 3.2, which leads to a significant reduction of the true distance moduli.

  15. Melatonin reduces obesity and restores adipokine patterns and metabolism in obese (ob/ob) mice.

    PubMed

    Favero, Gaia; Stacchiotti, Alessandra; Castrezzati, Stefania; Bonomini, Francesca; Albanese, Massimo; Rezzani, Rita; Rodella, Luigi Fabrizio

    2015-10-01

    The increasing incidence of obesity, leading to metabolic complications, is now recognized as a major public health problem. The adipocytes are not merely energy-storing cells, but they play crucial roles in the development of the so-called metabolic syndrome due to the adipocyte-derived bioactive factors such as adipokines, cytokines, and growth factors. The dysregulated production and secretion of adipokines seen in obesity is linked to the pathogenesis of the metabolic disease processes. In this study, we hypothesized that dietary melatonin administration would support an anti-inflammatory response and play an important role in energy metabolism in subcutaneous and visceral adipose tissues of obese mice and so may counteract some of the disruptive effects of obesity. Lean and obese mice (ob/ob) received melatonin or vehicle in drinking water for 8 weeks. Thereafter, they were evaluated for morphologic alteration, inflammatory cell infiltration, and the adipokine patterns in visceral and subcutaneous white fat depots. In obese mice treated with vehicle, we observed a significant increase in fat depots, inflammation, and a dysregulation of the adipokine network. In particular, we measured a significant reduction of adiponectin and an increase of tumor necrosis factor α, resistin, and visfatin in adipose tissue deposits. These changes were partially reversed when melatonin was supplemented to obese mice. Melatonin supplementation by regulating inflammatory infiltration ameliorates obesity-induced adipokine alteration, whereas melatonin administration in lean mice was unaffected. Thus, it is likely that melatonin would be provided in supplement form to control some of the disruptive effects on the basis of obesity pathogenic process.

  16. Hypothalamic Leptin Gene Therapy Reduces Bone Marrow Adiposity in ob/ob Mice Fed Regular and High-Fat Diets

    PubMed Central

    Lindenmaier, Laurence B.; Philbrick, Kenneth A.; Branscum, Adam J.; Kalra, Satya P.; Turner, Russell T.; Iwaniec, Urszula T.

    2016-01-01

    Low bone mass is often associated with elevated bone marrow adiposity. Since osteoblasts and adipocytes are derived from the same mesenchymal stem cell (MSC) progenitor, adipocyte formation may increase at the expense of osteoblast formation. Leptin is an adipocyte-derived hormone known to regulate energy and bone metabolism. Leptin deficiency and high-fat diet-induced obesity are associated with increased marrow adipose tissue (MAT) and reduced bone formation. Short-duration studies suggest that leptin treatment reduces MAT and increases bone formation in leptin-deficient ob/ob mice fed a regular diet. Here, we determined the long-duration impact of increased hypothalamic leptin on marrow adipocytes and osteoblasts in ob/ob mice following recombinant adeno-associated virus (rAAV) gene therapy. Eight- to 10-week-old male ob/ob mice were randomized into four groups: (1) untreated, (2) rAAV-Lep, (3) rAAV-green fluorescent protein (rAAV-GFP), or (4) pair-fed to rAAV-Lep. For vector administration, mice were injected intracerebroventricularly with either rAAV-leptin gene therapy (rAAV-Lep) or rAAV-GFP (9 × 107 particles) and maintained for 30 weeks. In a second study, the impact of increased hypothalamic leptin levels on MAT was determined in mice fed high-fat diets; ob/ob mice were randomized into two groups and treated with either rAAV-Lep or rAAV-GFP. At 7 weeks post-vector administration, half the mice in each group were switched to a high-fat diet for 8 weeks. Wild-type (WT) controls included age-matched mice fed regular or high-fat diet. High-fat diet resulted in a threefold increase in MAT in WT mice, whereas MAT was increased by leptin deficiency up to 50-fold. Hypothalamic leptin gene therapy increased osteoblast perimeter and osteoclast perimeter with minor change in cancellous bone architecture. The gene therapy decreased MAT levels in ob/ob mice fed regular or high-fat diet to values similar to WT mice fed regular diet. These findings suggest

  17. Consumption of a glucose diet enhances the sensitivity of pancreatic islets from adrenalectomized genetically obese (ob/ob) mice to glucose-induced insulin secretion.

    PubMed

    Mistry, A M; Chen, N G; Lee, Y S; Romsos, D R

    1995-03-01

    Consumption of a glucose diet for 4 d markedly elevates plasma insulin concentrations in adrenalectomized ob/ob mice. The present study examined regulation of insulin secretion from perifused pancreatic islets of female adrenalectomized genetically obese (ob/ob) and lean mice fed a glucose diet for 4 d. These mice were fed a high carbohydrate commercial diet for 21 d, or the high carbohydrate commercial diet for 17 d and a purified high glucose diet for the last 4 d of the 21-d feeding period. Adrenalectomy equalized plasma insulin concentrations, pancreatic islet size, rates of insulin secretion in response to 20 mmol/L glucose and insulin mRNA relative abundance in ob/ob and lean mice fed the commercial diet, but the threshold for glucose-induced insulin secretion determined by a linear glucose gradient remained lower in islets from adrenalectomized ob/ob mice than in those from lean mice (3.8 +/- 0.1 vs. 4.9 +/- 0.2 mmol/L glucose), and addition of acetylcholine to the perifusate lowered the threshold to only 2.0 +/- 0.1 mmol/L glucose in islets from ob/ob mice vs. 3.3 +/- 0.1 mmol/L glucose in lean mice. Switching from the commercial diet to the glucose diet for 4 d increased plasma insulin concentrations -10-fold in islets from adrenalectomized ob/ob mice without affecting islet size, 20 mmol/L glucose-induced insulin secretion or insulin mRNA abundance. Consumption of the glucose diet did, however, markedly lower the threshold for glucose-induced insulin secretion in islets from adrenalectomized ob/ob mice to approximate the abnormally low glucose thresholds in intact ob/ob mice.(ABSTRACT TRUNCATED AT 250 WORDS)

  18. Pentoxifylline aggravates fatty liver in obese and diabetic ob/ob mice by increasing intestinal glucose absorption and activating hepatic lipogenesis

    PubMed Central

    Massart, J; Robin, MA; Noury, F; Fautrel, A; Lettéron, P; Bado, A; Eliat, PA; Fromenty, B

    2012-01-01

    BACKGROUND AND PURPOSE Pentoxifylline is in clinical trials for non-alcoholic fatty liver disease and diabetic nephropathy. Metabolic and hepatic effects of pentoxifylline were assessed in a murine model of obesity and type 2 diabetes. EXPERIMENTAL APPROACH Pentoxifylline (100 mg·kg−1·day−1) was administered for 4 days or 3 weeks in lean and obese/diabetic ob/ob mice. Plasma lipids, glucose, other metabolites and relevant enzymes were measured by standard assays. Hepatic lipids in vivo were assessed with magnetic resonance spectroscopy and by histology. Hepatic extracts were also analysed with RT-PCR and Western blotting. KEY RESULTS Four days of pentoxifylline treatment slightly increased liver lipids in ob/ob mice. After 3 weeks, pentoxifylline exacerbated fatty liver and plasma transaminases in ob/ob mice but did not induce liver steatosis in lean mice. Plasma glucose was highest in fed, but not fasted, ob/ob mice treated with pentoxifylline. During the first 10 min of an oral glucose tolerance test, blood glucose increased more rapidly in pentoxifylline-treated mice. Jejunal expression of glucose transporter 2 isoform was increased in pentoxifylline-treated obese mice. Hepatic activity of carbohydrate response element binding protein (ChREBP) increased after pentoxifylline in ob/ob, but not lean, mice. Hepatic expression of lipogenic enzymes was highest in pentoxifylline-treated ob/ob mice. However, pentoxifylline reduced markers of oxidative stress and inflammation in ob/ob liver. CONCLUSION AND IMPLICATIONS Pentoxifylline exacerbated fatty liver in ob/ob mice through enhanced intestinal glucose absorption, increased postprandial glycaemia and activation of hepatic lipogenesis. Long-term treatment with pentoxifylline could worsen fatty liver in some patients with pre-existing hyperglycaemia. PMID:21740407

  19. No evidence of disk destruction by OB stars

    NASA Astrophysics Data System (ADS)

    Richert, Alexander J. W.; Feigelson, Eric

    2015-01-01

    It has been suggested that the hostile environments observed in massive star forming regions are inhospitable to protoplanetary disks and therefore to the formation of planets. The Orion Proplyds show disk evaporation by extreme ultraviolet (EUV) photons from Theta1 Orionis C (spectral type O6). In this work, we examine the spatial distributions of disk-bearing and non-disk bearing young stellar objects (YSOs) relative to OB stars in 17 massive star forming regions in the MYStIX (Massive Young Star-Forming Complex Study in Infrared and X-ray) survey. Any tendency of disky YSOs, identified by their infrared excess, to avoid OB stars would reveal complete disk destruction.We consider a sample of MYStIX that includes 78 O3-O9 stars, 256 B stars, 5,606 disky YSOs, and 5,794 non-disky YSOs. For each OB star, we compare the cumulative distribution functions of distances to disky and non-disky YSOs. We find no significant avoidance of OB stars by disky YSOs. This result indicates that OB stars are not sufficiently EUV-luminous and long-lived to completely destroy a disk within its ordinary lifetime. We therefore conclude that massive star forming regions are not clearly hostile to the formation of planets.

  20. Intra-islet lesions and lobular variations in β-cell mass expansion in ob/ob mice revealed by 3D imaging of intact pancreas

    PubMed Central

    Parween, Saba; Kostromina, Elena; Nord, Christoffer; Eriksson, Maria; Lindström, Per; Ahlgren, Ulf

    2016-01-01

    The leptin deficient ob/ob mouse is a widely used model for studies on initial aspects of metabolic disturbances leading to type 2 diabetes, including insulin resistance and obesity. Although it is generally accepted that ob/ob mice display a dramatic increase in β-cell mass to compensate for increased insulin demand, the spatial and quantitative dynamics of β-cell mass distribution in this model has not been assessed by modern optical 3D imaging techniques. We applied optical projection tomography and ultramicroscopy imaging to extract information about individual islet β-cell volumes throughout the volume of ob/ob pancreas between 4 and 52 weeks of age. Our data show that cystic lesions constitute a significant volume of the hyperplastic ob/ob islets. We propose that these lesions are formed by a mechanism involving extravasation of red blood cells/plasma due to increased islet vessel blood flow and vessel instability. Further, our data indicate that the primary lobular compartments of the ob/ob pancreas have different potentials for expanding their β-cell population. Unawareness of the characteristics of β-cell expansion in ob/ob mice presented in this report may significantly influence ex vivo and in vivo assessments of this model in studies of β-cell adaptation and function. PMID:27713548

  1. OB protein binds specifically to the choroid plexus of mice and rats.

    PubMed Central

    Devos, R; Richards, J G; Campfield, L A; Tartaglia, L A; Guisez, Y; van der Heyden, J; Travernier, J; Plaetinck, G; Burn, P

    1996-01-01

    Binding studies were conducted to identify the anatomical location of brain target sites for OB protein, the ob gene product. 125I-labeled recombinant mouse OB protein or alkaline phosphatase-OB fusion proteins were used for in vitro and in vivo binding studies. Coronal brain sections or fresh tissue from lean, obese ob/ob, and obese db/db mice as well as lean and obese Zucker rats were probed to identify potential central OB protein-binding sites. We report here that recombinant OB protein binds specifically to the choroid plexus. The binding of OB protein (either radiolabeled or the alkaline phosphatase-OB fusion protein) and its displacement by unlabeled OB protein was similar in lean, obese ob/ob, and obese db/db mice as well as lean and obese Zucker rats. These findings suggest that OB protein binds with high affinity to a specific receptor in the choroid plexus. After binding to the choroid plexus receptor, OB protein may then be transported across the blood-brain barrier into the cerebrospinal fluid. Alternatively, binding of OB protein to a specific receptor in the choroid plexus may activate afferent neural inputs to the neural network that regulates feeding behavior and energy balance or may result in the clearance or degradation of OB protein. The identification of the choroid plexus as a brain binding site for OB protein will provide the basis for the construction of expression libraries and facilitate the rapid cloning of the choroid plexus OB receptor. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:8643634

  2. Study of the ice conditions in the Gulf of Ob

    NASA Astrophysics Data System (ADS)

    Zyryanov, D. V.; Smirnov, V. N.

    2006-03-01

    The results of theoretical studies of fracture lines in the ice floes of the Gulf of Ob as a function of the coefficient of internal sliding are presented in this paper. An estimate of the fractal dimensions of the emerging topological structures and the results of the calculation of stresses in the ice cover of the Gulf of Ob are presented as functions of different directions of external forcing caused by the joint action of winds and currents on the ice. The geographical locations of the zones of possible loads are shown, together with the estimates of the hummock sizes in the zones of the maximal compression of the ice floes in the Gulf of Ob.

  3. Substructure In The Scorpius-Centaurus OB Association

    NASA Astrophysics Data System (ADS)

    Pecaut, Mark J.; Mamajek, Eric E.

    2016-07-01

    OB associations are remnants of star formation on a large scale, producing everything from O- and B-type stars, down to the lowest mass brown dwarfs. OB associations represent the typical mode of star formation in the Galaxy. But is this process monolithic? We present the results of a survey for new, solar mass (0.7 - 1.3 Msun) members of Sco-Cen, the nearest OB Association to the Sun. We identify 150 new members and place the known B/A/F/G/K/M-type members on the Hertzsprung-Russell diagram. From these data, we construct an age map of Sco-Cen, occupying approximately 2,000 square degrees on the sky. These results indicate there is substantial substructure in Sco-Cen, and present the possibility that star formation on the largest scales can be considered a collection of many individual, small-scale star formation events along a giant molecular cloud.

  4. OB associations and giant molecular clouds in the galaxy

    NASA Technical Reports Server (NTRS)

    Williams, Jonathan; Mckee, Chris

    1993-01-01

    Giant molecular clouds (GMC's) are the sites of all OB star formation in the Galaxy. These OB stars typically form in large associations and photoionize the surrounding gas, eventually destroying the clouds from which they were born. CO surveys have revealed the distribution of GMC's in the Galaxy, and radio observations provide data on the distribution of associations. These results are extrapolated to determine Galactic mean distribution functions of each and then combined to determine how GMC's and OB associations are correlated. The resulting probability distribution of luminosity given cloud mass implies that although most of the molecular mass of the Galaxy is in massive star forming complexes, a large number of clouds above which massive star formation is extremely likely and abundant and below which it is almost certainly absent.

  5. OB association members in the ACT and TRC catalogues

    NASA Astrophysics Data System (ADS)

    Hoogerwerf, Ronnie

    2000-03-01

    The Hipparcos Catalogue contains members of nearby OB associations brighter than 12th magnitude in V. However, membership lists are complete only to magnitude V=7.3. In this paper we discuss whether proper motions listed in the `Astrographic Catalogue+Tycho' reference catalogue (ACT) and the Tycho Reference Catalogue (TRC), which are complete to V~10.5mag, can be used to find additional association members. Proper motions in the ACT/TRC have an average accuracy of ~3masyr-1. We search for ACT/TRC stars which have proper motions consistent with the spatial velocity of the Hipparcos members of the nearby OB associations already identified by de Zeeuw et al. These stars are first selected using a convergent-point method, and then subjected to further constraints on the proper-motion distribution, magnitude and colour to narrow down the final number of candidate members. Monte Carlo simulations show that the proper-motion distribution, magnitude, and colour constraints remove ~97per cent of the field stars, while at the same time retain more than 90per cent of the cluster stars. The procedure has been applied to five nearby associations: the three subgroups of Sco OB2, plus Per OB3 and Cep OB6. In all cases except Cep OB6, we find evidence for new association members fainter than the completeness limit of the Hipparcos Catalogue. However, narrow-band photometry and/or radial velocities are needed to pinpoint the cluster members, and to study their physical characteristics.

  6. Reservation information sharing enhancement for deflection routing in OBS network.

    PubMed

    Gao, Donghui; Zhang, Hanyi; Zhou, Zhiyu

    2005-03-07

    The resource contention problem is critical in Just-Enough-Time (JET) based optical burst switching (OBS) networks. Although deflection routing (DR) reduces the contention probability in some degree, it does not give much improvement under heavy traffic load. This paper analyzed the inducement causing contention in OBS networks, and proposed Resource Information Sharing Enhancement (RISE) scheme. Theoretical analysis shows that this scheme achieves shorter length of the detour path than normal DR. We simulated this scheme on both full mesh network and practical 14-node NSFNET. The simulation results show that it gives at best 2 orders magnitude improvement in reducing the burst contention probability over its previous routing approaches.

  7. Molecular outflows in the Monoceros OB1 molecular cloud

    NASA Technical Reports Server (NTRS)

    Margulis, Michael; Lada, Charles J.; Snell, Ronald L.

    1988-01-01

    Observations of J = 1-0 emission from CO in nine suspected molecular outflows in the Monoceros OB1 molecular cloud are presented. It is found that, if the five sources which are confirmed to be outflows conserve momentum as they evolve, they will sweep up at least 0.6 percent of the mass of the entire cloud before coming into pressure equilibrium with the ambient gas. This number indicates that it should take at most 160 episodes of similar outflow activity in order to sweep up the bulk of the Mon OB1 cloud to highly supersonic speeds.

  8. Marine TAIGER OBS Experiment and its future prospects

    NASA Astrophysics Data System (ADS)

    Lee, C.; Wang, T.; van Avendonk, H. J.; Huang, Y.; Lin, J.; Lallemand, S.; Klingelhoeher, F.

    2009-12-01

    A total of 260 OBSs were deployed in the marine TAIGER program from late March to late July, 2009. These data were collected by US Columbia University’s R/V Langseth as the big-power seismic shooting ship and 10 Taiwanese ships to take terms for supporting of the OBS experiment in the entire seismic cruises. The OBS were provided by the National Taiwan Ocean University, French IFREMER and Scripps Institution of Oceanography. During these 4 months, we have worked around Taiwan in the South China Sea, Luzon Arc, East Taiwan and West Philippine Basin. All efforts are put together by many earth scientists from Taiwan, USA and France under one major purpose, to get a better understanding of the Taiwan mountain building processes. As a result, these new data will provide as a base to combine with many other disciplinal studies, such as the multi-channel seismic, land recorded seismometer data, gravity and magnetic as well as the natural earthquake data recorded by the OBS during the experiment time. Four very preliminary OBS data analyses will be presented in the same T25 postal section. Beside the research, we also carried out our teaching to our students on board a Taiwanese student training ship, Yu-Yin No.2. Therefore, an educational post is also to be shown in the ED01 section. Even the data analyses are in an early stage, but we are exciting about it. For example, 3 OBS profiles (T4, T5 and T6) in the East Taiwan were shot twice in normal and reversed directions with different shot intervals (30 and 60 seconds per shot). This exercise will be important to interpret the complicate collision/subduction structures in the East Taiwan. Two OBS profiles (T1 and T2) in the Luzon Arc were shot 5 times in the separated R/V Langseth cruises (due to the typhoon effects), again with different shot intervals (20 and 60 seconds per shot). These will provide us more opportunities to examine the collisional features in between Taiwan and Luzon. One OBS long profile (550 km) was

  9. The SGLT2 inhibitor empagliflozin ameliorates early features of diabetic nephropathy in BTBR ob/ob type 2 diabetic mice with and without hypertension.

    PubMed

    Gembardt, Florian; Bartaun, Christoph; Jarzebska, Natalia; Mayoux, Eric; Todorov, Vladimir T; Hohenstein, Bernd; Hugo, Christian

    2014-08-01

    Diabetic nephropathy is the leading cause of end-stage renal disease in humans in the Western world. The recent development of Na+-glucose cotransporter 2 (SGLT2) inhibitors offers a new antidiabetic therapy via enhanced glucose excretion. Whether this strategy exerts beneficial effects on the development of type 2 diabetic nephropathy is still largely unclear. We investigated the effects of the specific SGLT2 inhibitor empagliflozin in BTBR.Cg-Lep<ob>/WiscJ (BTBR ob/ob) mice, which spontaneously develop type 2 diabetic nephropathy. In the first experiment, BTBR ob/ob mice received either a diet containing 300 ppm empagliflozin or equicaloric placebo chow for 12 wk. In the second experiment, BTBR ob/ob mice received 1 μg·kg body wt(-1)·day(-1) ANG II to induce arterial hypertension and were separated into the same two diet groups for 6 wk. In both experiments, empagliflozin treatment enhanced glucosuria, thereby lowering blood glucose. Independently of hypertension, empagliflozin reduced albuminuria in diabetic mice. However, empagliflozin treatment affected diabetes-related glomerular hypertrophy, markers of renal inflammation, and mesangial matrix expansion only in BTBR ob/ob mice without hypertension. In summary, empagliflozin demonstrated significant antihyperglycemic effects, differentially ameliorating early features of diabetic nephropathy in BTBR ob/ob mice with and without hypertension.

  10. Hepatic VLDL production in ob/ob mice is not stimulated by massive de novo lipogenesis but is less sensitive to the suppressive effects of insulin.

    PubMed

    Wiegman, Coen H; Bandsma, Robert H J; Ouwens, Margriet; van der Sluijs, Fjodor H; Havinga, Rick; Boer, Theo; Reijngoud, Dirk-Jan; Romijn, Johannes A; Kuipers, Folkert

    2003-05-01

    Type 2 diabetes in humans is associated with increased de novo lipogenesis (DNL), increased fatty acid (FA) fluxes, decreased FA oxidation, and hepatic steatosis. In this condition, VLDL production is increased and resistant to suppressive effects of insulin. The relationships between hepatic FA metabolism, steatosis, and VLDL production are incompletely understood. We investigated VLDL-triglyceride and -apolipoprotein (apo)-B production in relation to DNL and insulin sensitivity in female ob/ob mice. Hepatic triglyceride (5-fold) and cholesteryl ester (15-fold) contents were increased in ob/ob mice compared with lean controls. Hepatic DNL was increased approximately 10-fold in ob/ob mice, whereas hepatic cholesterol synthesis was not affected. Basal rates of hepatic VLDL-triglyceride and -apoB100 production were similar between the groups. Hyperinsulinemic clamping reduced VLDL-triglyceride and -apoB100 production rates by approximately 60% and approximately 75%, respectively, in lean mice but only by approximately 20% and approximately 20%, respectively, in ob/ob mice. No differences in hepatic expression of genes encoding apoB and microsomal triglyceride transfer protein were found. Hepatic expression and protein phosphorylation of insulin receptor and insulin receptor substrate isoforms were reduced in ob/ob mice. Thus, strongly induced hepatic DNL is not associated with increased VLDL production in ob/ob mice, possibly related to differential hepatic zonation of apoB synthesis (periportal) and lipid accumulation (perivenous) and/or relatively low rates of cholesterogenesis. Insulin is unable to effectively suppress VLDL-triglyceride production in ob/ob mice, presumably because of impaired insulin signaling.

  11. Nonspherical supernova remnants. IV - Sequential explosions in OB associations

    NASA Technical Reports Server (NTRS)

    Tenorio-Tagle, G.; Bodenheimer, P.; Rozyczka, M.

    1987-01-01

    Multisupernova remnants, driven by sequential supernova explosions in OB associations, are modelled by means of two-dimensional hydrodynamical calculations. It is shown that due to the Rayleigh-Taylor instability the remnants quickly evolve into highly irregular structures. A critical evaluation of the multisupernova model as an explanation for supershells is given.

  12. OB/OOCH Upstream 2007: Reflections on an Upstream Journey

    ERIC Educational Resources Information Center

    Edmonstone, Laura

    2008-01-01

    In this article, the author shares her experience of spending time at Camp Oochigeas as an Outward Bound (OB) instructor. The author was there as part of a team, working in a program that partnered three strong organizations with a wealth of knowledge and experience in working with kids. Camp Oochigeas operates a volunteer-based program for kids…

  13. OB-stars as extreme condition test beds

    NASA Astrophysics Data System (ADS)

    Puls, Joachim; Sundqvist, Jon O.; Rivero González, Jorge G.

    2011-07-01

    Massive stars are inherently extreme objects, in terms of radiation, mass loss, rotation, and sometimes also magnetic fields. Concentrating on a (personally biased) subset of processes related to pulsations, rapid rotation and its interplay with mass-loss, and the bi-stability mechanism, we will discuss how active (and normal) OB stars can serve as appropriate laboratories to provide further clues.

  14. The massive star population of Cygnus OB2

    NASA Astrophysics Data System (ADS)

    Wright, Nicholas J.; Drew, Janet E.; Mohr-Smith, Michael

    2015-05-01

    We have compiled a significantly updated and comprehensive census of massive stars in the nearby Cygnus OB2 association by gathering and homogenizing data from across the literature. The census contains 169 primary OB stars, including 52 O-type stars and 3 Wolf-Rayet stars. Spectral types and photometry are used to place the stars in a Hertzsprung-Russell diagram, which is compared to both non-rotating and rotating stellar evolution models, from which stellar masses and ages are calculated. The star formation history and mass function of the association are assessed, and both are found to be heavily influenced by the evolution of the most massive stars to their end states. We find that the mass function of the most massive stars is consistent with a `universal' power-law slope of Γ = 1.3. The age distribution inferred from stellar evolutionary models with rotation and the mass function suggest the majority of star formation occurred more or less continuously between 1 and 7 Myr ago, in agreement with studies of low- and intermediate-mass stars in the association. We identify a nearby young pulsar and runaway O-type star that may have originated in Cyg OB2 and suggest that the association has already seen its first supernova. Finally we use the census and mass function to calculate the total mass of the association of 16 500^{+3800}_{-2800} M⊙, at the low end, but consistent with, previous estimates of the total mass of Cyg OB2. Despite this Cyg OB2 is still one of the most massive groups of young stars known in our Galaxy making it a prime target for studies of star formation on the largest scales.

  15. ObsPy: A Python Toolbox for Seismology

    NASA Astrophysics Data System (ADS)

    Wassermann, J. M.; Krischer, L.; Megies, T.; Barsch, R.; Beyreuther, M.

    2013-12-01

    Python combines the power of a full-blown programming language with the flexibility and accessibility of an interactive scripting language. Its extensive standard library and large variety of freely available high quality scientific modules cover most needs in developing scientific processing workflows. ObsPy is a community-driven, open-source project extending Python's capabilities to fit the specific needs that arise when working with seismological data. It a) comes with a continuously growing signal processing toolbox that covers most tasks common in seismological analysis, b) provides read and write support for many common waveform, station and event metadata formats and c) enables access to various data centers, webservices and databases to retrieve waveform data and station/event metadata. In combination with mature and free Python packages like NumPy, SciPy, Matplotlib, IPython, Pandas, lxml, and PyQt, ObsPy makes it possible to develop complete workflows in Python, ranging from reading locally stored data or requesting data from one or more different data centers via signal analysis and data processing to visualization in GUI and web applications, output of modified/derived data and the creation of publication-quality figures. All functionality is extensively documented and the ObsPy Tutorial and Gallery give a good impression of the wide range of possible use cases. ObsPy is tested and running on Linux, OS X and Windows and comes with installation routines for these systems. ObsPy is developed in a test-driven approach and is available under the LGPLv3 open source licence. Users are welcome to request help, report bugs, propose enhancements or contribute code via either the user mailing list or the project page on GitHub.

  16. The relationship between protein turnover and energy balance in lean and genetically obese (ob/ob) mice.

    PubMed

    Miller, B G; Otto, W R; Grimble, R F; York, D A; Taylor, T G

    1979-09-01

    1. Groups of lean and genetically obese (ob/ob) mice were adapted to varying energy intakes and the rates of total protein turnover in liver, gut and kidney were measured. 2. Lean mice gained less weight when fed above maintenance and lost less weight when fed below maintance than obese mice. 3. Hepatic protein turnover (mg/d) was sigmoidally related to digestible energy intake in lean mice but showed no significant changes with dietary intake in obese mice. 4. The changes in protein turnover resulted from changes in both the half-lives of protein synthesis and catabolism and in tissue protein content. 5. In the lean mice, protein turnover in kidney and gut was not significantly changed with increasing energy intake until the highest level was reached. 6. The findings suggest that protein turnover may be an important cycle for the regulation of energy balance in mice and that this cycle is impaired in the genetically obese (ob/ob) mice.

  17. iPLA2β deficiency attenuates obesity and hepatic steatosis in ob/ob mice through hepatic fatty-acyl phospholipid remodeling.

    PubMed

    Deng, Xiuling; Wang, Jiliang; Jiao, Li; Utaipan, Tanyarath; Tuma-Kellner, Sabine; Schmitz, Gerd; Liebisch, Gerhard; Stremmel, Wolfgang; Chamulitrat, Walee

    2016-05-01

    PLA2G6 or GVIA calcium-independent PLA2 (iPLA2β) is identified as one of the NAFLD modifier genes in humans, and thought to be a target for NAFLD therapy. iPLA2β is known to play a house-keeping role in phospholipid metabolism and remodeling. However, its role in NAFLD pathogenesis has not been supported by results obtained from high-fat feeding of iPLA2β-null (PKO) mice. Unlike livers of human NAFLD and genetically obese rodents, fatty liver induced by high-fat diet is not associated with depletion of hepatic phospholipids. We therefore tested whether iPLA2β could regulate obesity and hepatic steatosis in leptin-deficient mice by cross-breeding PKO with ob/ob mice to generate ob/ob-PKO mice. Here we observed an improvement in ob/ob-PKO mice with significant reduction in serum enzymes, lipids, glucose, insulin as well as improved glucose tolerance, and reduction in islet hyperplasia. The improvement in hepatic steatosis measured by liver triglycerides, fatty acids and cholesterol esters was associated with decreased expression of PPARγ and de novo lipogenesis genes, and the reversal of β-oxidation gene expression. Notably, ob/ob livers contained depleted levels of lysophospholipids and phospholipids, and iPLA2β deficiency in ob/ob-PKO livers lowers the former, but replenished the latter particularly phosphatidylethanolamine (PE) and phosphatidylcholine (PC) that contained arachidonic (AA) and docosahexaenoic (DHA) acids. Compared with WT livers, PKO livers also contained increased PE and PC containing AA and DHA. Thus, iPLA2β deficiency protected against obesity and ob/ob fatty liver which was associated with hepatic fatty-acyl phospholipid remodeling. Our results support the deleterious role of iPLA2β in severe obesity associated NAFLD.

  18. An infrared supershell surrounding the Cygnus OB1 association

    NASA Technical Reports Server (NTRS)

    Saken, Jon M.; Shull, J. M.; Garmany, Catharine D.; Nichols-Bohlin, Joy; Fesen, Robert A.

    1992-01-01

    New studies are reported of a large, 2 x 5 deg peanut-shaped cavity in the far-infrared emission seen using IRAS data for the Cygnus X region. A more complete and better defined infrared supershell than reported by Lozinskaya and Repin (1990) is found and connected to the Cyg OB1 association. It is shown that the cavity represents the early stages of a superbubble produced by the winds and possible SNe from 10 to 20 massive stars. The locations and properties of these stars are used to estimate the energy deposition rate and to understand the manner in which supershells form and propagate. In Cyg OB1, spatially distributed subclustering appears to have played an important role in determining the nonspherical morphology of the superbubble.

  19. Analysis of Hybrid Buffering and Retransmission in OBS Networks.

    PubMed

    Vanitha, D Veera; Sabrigiriraj, M

    2015-01-01

    Burst contention is a major problem in the Optical Burst Switching (OBS) networks. Due to inadequate contention resolution techniques, the burst loss is prominent in OBS. In order to resolve contention fiber delay lines, wavelength converters, deflection routing, burst segmentation, and retransmission are used. Each one has its own limitations. In this paper, a new hybrid scheme is proposed which combines buffering and retransmission, which increases the mean number of bursts processed in the system. In this hybrid method, retransmission with controllable arrival and uncontrollable arrival is analyzed. Normally all the bursts reach the first hop and few of them go for second hop to reach destination. After all the bursts reach the destination the server may go for maintenance activity or wait for the arrival of next burst. We model it as a batch arrival single server retrial queue with buffer. Numerical results are analyzed to show the mean number of bursts processed in the system with uncontrollable arrival and controllable arrivals.

  20. Biodegradation of trichloroethylene by Methylosinus trichosporium OB3b.

    PubMed Central

    Tsien, H C; Brusseau, G A; Hanson, R S; Waclett, L P

    1989-01-01

    The methanotroph Methylosinus trichosporium OB3b, a type II methanotroph, degraded trichloroethylene at rates exceeding 1.2 mmol/h per g (dry weight) following the appearance of soluble methane monooxygenase in continuous and batch cultures. Cells capable oxidizing trichloroethylene contained components of soluble methane monooxygenase as demonstrated by Western blot (immunoblot) analysis with antibodies prepared against the purified enzyme. Growth of cultures in a medium containing 0.25 microM or less copper sulfate caused derepression of the synthesis of soluble methane monooxygenase. In these cultures, the specific rates of methane and methanol oxidation did not change during growth, while trichloroethylene oxidation increased with the appearance of soluble methane monooxygenase. M. trichosporium OB3b cells that contained soluble methane monooxygenase also degraded vinyl chloride, 1,1-dichloroethylene, cis-1,2-dichloroethylene, and trans-1,2-dichloroethylene. Images PMID:2515801

  1. OB stars in the Leading Arm of the Magellanic Stream

    NASA Astrophysics Data System (ADS)

    Moni Bidin, C.; Casetti-Dinescu, D. I.; Méndez, R. A.; Girard, T. M.; Vieira, K.; Korchagin, V. I.; van Altena, W. F.

    2015-05-01

    We present our spectroscopic program aimed to study some new interesting features recently discovered in the Magellanic Cloud System. These were revealed by the spatial distribution of OB-type candidate stars selected based on UV, optical, and IR photometry and proper motions from existing large-area catalogs. As a pilot study of our project, we are studying OB-star candidates in the Leading Arm (LA) of the Magellanic Stream, a gaseous tidal structure with no stellar counterpart known so far. Our targets group in three clumps near regions of high HI density in the LA. If confirmed, these young stars would evidence recent star formation in the LA, and they would help better understand and constrain the formation of the LA and its interactions with the Milky Way.

  2. Converting near-bottom OBS measurements into suspended sediment concentrations

    USGS Publications Warehouse

    Xu, J. P.

    1997-01-01

    A method of estimating the mass proportion of nonhomogeneous sediment constituents in suspension is presented. This method provides a more accurate conversion of OBS measurements (volts) to suspended sediment concentrations (grams per liter). Given a set of calibration coefficients of end-members, the method allows one to obtain the spatially and temporally varying in situ coefficients that are used in the conversion. Field and/or laboratory experiments are needed to verify the method.

  3. Flooding of the Ob and Irtysh Rivers, Russia

    NASA Technical Reports Server (NTRS)

    2002-01-01

    These images from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Terra satellite shows the cause and effect of the large-scale seasonal flooding experienced on rivers throughout Siberia each year. Because many Siberian rivers flow from south to north, they flood regularly in the spring as meltwater from southern latitudes backs up against the still-frozen northern reaches of the rivers.These images show the Ob' River on the western edge of the Central Siberian Plateau. The images from June 20, 2002, show the mouth of the Ob' River (large river at left) where it empties into Kara Sea. In the false-color image, Vegetation appears in bright green, water appears dark blue or black, and ice appears bright blue. The ice is still choking the river's outlet to the sea.The effect of this ice block on the more southern stretches of the river can be seen in the images captured on June 17. In the false-color image, water is black, vegetation is in shades of gold and green, and clouds are pale orange. In the northernmost portion of the Ob' visible in this image (the Ob' runs southeast to northwest in the image), what is normally a fine mesh of braided streams and branches of the river channel has become almost a lake in places. The flood waters have engorged the river to 52 kilometers (32 miles) wide in places. Rivers can back up for hundreds of miles, and cause devastating flooding for towns and villages along the banks. Often, explosives are dropped into ice jams in an effort to free the river and give the flood waters a chance to escape. The spring and summer floods of 2002 have proven to be quite severe and perhaps as many as 100,000 people have been affected across the country. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  4. A spectroscopic and photometric survey of OB+ stars

    NASA Technical Reports Server (NTRS)

    Drilling, J. S.

    1987-01-01

    Image-tube spectra (with dispersions of 40-90 A/mm) and UBV photometry of OB+ stars have been obtained at Cerro Tololo and Kitt Peak. The survey is complete to galactic latitudes of + or - 30 deg for galactic longitudes of between 300 and 60 deg. Most of the stars are found to be O-type and B-type supergiants, and 378 new O-type and B-type detections have been identified.

  5. PHOTOEVAPORATING PROPLYD-LIKE OBJECTS IN CYGNUS OB2

    SciTech Connect

    Wright, Nicholas J.; Drake, Jeremy J.; Guarcello, Mario G.; Hora, Joseph L.; Drew, Janet E.; Gutermuth, Robert A.; Kraemer, Kathleen E.

    2012-02-20

    We report the discovery of 10 proplyd-like objects in the vicinity of the massive OB association Cygnus OB2. They were discovered in IPHAS H{alpha} images and are clearly resolved in broadband Hubble Space Telescope/Advanced Camera for Surveys, near-IR, and Spitzer mid-IR images. All exhibit the familiar tadpole shape seen in photoevaporating objects such as the Orion proplyds, with a bright ionization front at the head facing the central cluster of massive stars and a tail stretching in the opposite direction. Many also show secondary ionization fronts, complex tail morphologies, or multiple heads. We consider the evidence that these are either proplyds or 'evaporating gaseous globules' (EGGs) left over from a fragmenting molecular cloud, but find that neither scenario fully explains the observations. Typical sizes are 50,000-100,000 AU, larger than the Orion proplyds, but in agreement with the theoretical scaling of proplyd size with distance from the ionizing source. These objects are located at projected separations of {approx}6-14 pc from the OB association, compared to {approx}0.1 pc for the Orion proplyds, but are clearly being photoionized by the {approx}65 O-type stars in Cyg OB2. Central star candidates are identified in near- and mid-IR images, supporting the proplyd scenario, though their large sizes and notable asymmetries are more consistent with the EGG scenario. A third possibility is therefore considered that these are a unique class of photoevaporating partially embedded young stellar objects that have survived the destruction of their natal molecular cloud. This has implications for the properties of stars that form in the vicinity of massive stars.

  6. FIVE MORE MASSIVE BINARIES IN THE CYGNUS OB2 ASSOCIATION

    SciTech Connect

    Kiminki, Daniel C.; Kobulnicky, Henry A.; Gilbert, Ian; Bird, Sarah; Chunev, Georgi

    2009-06-15

    We present the orbital solutions for four OB spectroscopic binaries, MT145, GSC 03161 - 00815, 2MASS J20294666+4105083, and Schulte 73, and the partial orbital solution to the B spectroscopic binary, MT372, as part of an ongoing study to determine the distribution of orbital parameters for massive binaries in the Cygnus OB2 Association. MT145 is a new, single-lined, moderately eccentric (e = 0.291 {+-} 0.009) spectroscopic binary with period of 25.140 {+-} 0.008 days. GSC 03161 - 00815 is a slightly eccentric (e = 0.10 {+-} 0.01), eclipsing, interacting and double-lined spectroscopic binary with a period of 4.674 {+-} 0.004 days. 2MASS J20294666+4105083 is a moderately eccentric (e = 0.273 {+-} 0.002) double-lined spectroscopic binary with a period of 2.884 {+-} 0.001 days. Schulte 73 is a slightly eccentric (e = 0.169 {+-} 0.009), double-lined spectroscopic binary with a period of 17.28 {+-} 0.03 days and the first 'twin' in our survey with a mass ratio of q = 0.99 {+-} 0.02. MT372 is a single-lined, eclipsing system with a period of 2.228 days and low eccentricity (e {approx} 0). Of the now 18 known OB binaries in Cyg OB2, 14 have periods and mass ratios. Emerging evidence also shows that the distribution of log(P) is flat and consistent with 'Oepik's Law'.

  7. ADDITIONAL MASSIVE BINARIES IN THE CYGNUS OB2 ASSOCIATION

    SciTech Connect

    Kiminki, Daniel C.; Kobulnicky, Henry A.; Ewing, Ian; Lundquist, Michael; Alexander, Michael; Vargas-Alvarez, Carlos; Choi, Heather; Bagley Kiminki, Megan M.; Henderson, C. B.

    2012-03-01

    We report the discovery and orbital solutions for two new OB binaries in the Cygnus OB2 Association, MT311 (B2V + B3V) and MT605 (B0.5V + B2.5:V). We also identify the system MT429 as a probable triple system consisting of a tight eclipsing 2.97 day B3V+B6V pair and a B0V at a projected separation of 138 AU. We further provide the first spectroscopic orbital solutions to the eclipsing, double-lined, O-star binary MT696 (O9.5V + B1:V), the double-lined, early B binary MT720 (B0-1V + B1-2V), and the double-lined, O-star binary MT771 (O7V + O9V). These systems exhibit orbital periods between 1.5 days and 12.3 days, with the majority having P <6 days. The two new binary discoveries and six spectroscopic solutions bring the total number of known massive binaries in the central region of the Cygnus OB2 Association to 20, with all but two having full orbital solutions.

  8. A SAMPLE OF OB STARS THAT FORMED IN THE FIELD

    SciTech Connect

    Oey, M. S.; Lamb, J. B.; Kushner, C. T.; Pellegrini, E. W.; Graus, A. S.

    2013-05-01

    We present a sample of 14 OB stars in the Small Magellanic Cloud that meet strong criteria for having formed under extremely sparse star-forming conditions in the field. These stars are a minimum of 28 pc in projection from other OB stars, and they are centered within symmetric, round H II regions. They show no evidence of bow shocks, implying that the targets are not transverse runaway stars. Their radial velocities relative to local H I also indicate that they are not line-of-sight runaway stars. A friends-of-friends analysis shows that nine of the objects present a few low-mass companion stars, with typical mass ratios for the two highest-mass stars of around 0.1. This further substantiates that these OB stars formed in place, and that they can and do form in extremely sparse conditions. This poses strong constraints on theories of star formation and challenges proposed relations between cluster mass and maximum stellar mass.

  9. Non-thermal emission in Cyg OB2

    NASA Astrophysics Data System (ADS)

    Fenech, D.; Morford, J.; Prinja, R.

    2017-03-01

    We report here on the first results from the Cyg OB2 Radio Survey (COBRaS), which is a UCL-led e-MERLIN legacy project to provide a deep-field radio mapping of the Cygnus OB2 association. The project has been awarded a total allocation of 252 hours at C-band (5 GHz) and 42 hours at L-band (1.6 GHz) to image the core of the cluster. We discuss in particular the presence of non-thermal radio emission at 20 cm (L-band), and its potential as a highly efficient way to identify binaries via single-epoch observations, particularly for colliding-wind binaries. COBRaS data will provide a powerful tool for establishing binary incidence in Cyg OB2, specifically in the difficult intermediate-period range (1-100 yr). Ultimately, we aim to assemble a substantial and uniquely sensitive radio dataset, which will be exploited to address several fundamentally important areas of stellar astrophysics, including mass-loss, binary frequency, stellar cluster dynamics, and triggered star-formation.

  10. Development of an anorthositic lunar regolith simulant: OB-1

    NASA Astrophysics Data System (ADS)

    Battler, Melissa Marie

    With the expected return of astronauts to the Moon before 2020 and construction of a permanent lunar base, there is a renewed need to understand the lunar surface environment. It is necessary to determine optimal methods for operations in the lunar regolith at selected landing sites. Regolith is the unconsolidated, abrasive material blanketing the lunar surface (up to ˜15 m thick), and will be the point of contact for humans and infrastructure. It is unlike any material naturally occurring on Earth. This thesis describes the development of the anorthositic physical/mechanical lunar regolith simulant "OB-I", designed for testing robotic lunar drilling and excavation equipment. The simulant comprises terrestrial anorthosite and slag, which have been comminuted and sized with jaw, roll, and ring crushers. OB-1 has been characterized using optical and electron microscopy, X-ray fluorescence spectroscopy, and various particle sizing methods. The resultant grain shapes, size distributions, and mineralogies are comparable to Apollo 16 regolith samples, making the OB-1 simulant appropriate for validating robotic lunar equipment on Earth.

  11. Leptin Reduces the Expression and Increases the Phosphorylation of the Negative Regulators of GLUT4 Traffic TBC1D1 and TBC1D4 in Muscle of ob/ob Mice

    PubMed Central

    Sáinz, Neira; Rodríguez, Amaia; Catalán, Victoria; Becerril, Sara; Ramírez, Beatriz; Lancha, Andoni; Burgos-Ramos, Emma; Gómez-Ambrosi, Javier; Frühbeck, Gema

    2012-01-01

    Leptin improves insulin sensitivity in skeletal muscle. Our goal was to determine whether proteins controlling GLUT4 traffic are altered by leptin deficiency and in vivo leptin administration in skeletal muscle of wild type and ob/ob mice. Leptin-deficient ob/ob mice were divided in three groups: control, leptin-treated (1 mg/kg/d) and leptin pair-fed ob/ob mice. Microarray analysis revealed that 1,546 and 1,127 genes were regulated by leptin deficiency and leptin treatment, respectively. Among these, we identified 24 genes involved in intracellular vesicle-mediated transport in ob/ob mice. TBC1 domain family, member 1 (Tbc1d1), a negative regulator of GLUT4 translocation, was up-regulated (P = 0.001) in ob/ob mice as compared to wild types. Importantly, leptin treatment reduced the transcript levels of Tbc1d1 (P<0.001) and Tbc1d4 (P = 0.004) in the leptin-treated ob/ob as compared to pair-fed ob/ob animals. In addition, phosphorylation levels of TBC1D1 and TBC1D4 were enhanced in leptin-treated ob/ob as compared to control ob/ob (P = 0.015 and P = 0.023, respectively) and pair-fed ob/ob (P = 0.036 and P = 0.034, respectively) mice. Despite similar GLUT4 protein expression in wild type and ob/ob groups a different immunolocalization of this protein was evidenced in muscle sections. Leptin treatment increased GLUT4 immunoreactivity in gastrocnemius and extensor digitorum longus sections of leptin-treated ob/ob mice. Moreover, GLUT4 protein detected in immunoprecipitates from TBC1D4 was reduced by leptin replacement compared to control ob/ob (P = 0.013) and pair-fed ob/ob (P = 0.037) mice. Our findings suggest that leptin enhances the intracellular GLUT4 transport in skeletal muscle of ob/ob animals by reducing the expression and activity of the negative regulators of GLUT4 traffic TBC1D1 and TBC1D4. PMID:22253718

  12. Thiazolidinediones repress ob gene expression in rodents via activation of peroxisome proliferator-activated receptor gamma.

    PubMed Central

    De Vos, P; Lefebvre, A M; Miller, S G; Guerre-Millo, M; Wong, K; Saladin, R; Hamann, L G; Staels, B; Briggs, M R; Auwerx, J

    1996-01-01

    The ob gene product, leptin, is a signaling factor regulating body weight and energy balance. ob gene expression in rodents is increased in obesity and is regulated by feeding patterns and hormones, such as insulin and glucocorticoids. In humans with gross obesity, ob mRNA levels are higher, but other modulators of human ob expression are unknown. In view of the importance of peroxisome proliferator-activated receptor gamma (PPARgamma) in adipocyte differentiation, we analyzed whether ob gene expression is subject to regulation by factors activating PPARs. Treatment of rats with the PPARalpha activator fenofibrate did not change adipose tissue and body weight and had no significant effect on ob mRNA levels. However, administration of the thiazolidinedione BRL49653, a PPARgamma ligand, increased food intake and adipose tissue weight while reducing ob mRNA levels in rats in a dose-dependent manner. The inhibitory action of the thiazolidinedione BRL49653 on ob mRNA levels was also observed in vitro. Thiazolidinediones reduced the expression of the human ob promoter in primary adipocytes, however, in undifferentiated 3T3-L1 preadipocytes lacking endogenous PPARgamma, cotransfection of PPARgamma was required to observe the decrease. In conclusion, these data suggest that PPARgamma activators reduce ob mRNA levels through an effect of PPARgamma on the ob promoter. PMID:8770873

  13. Cygnus OB2 DANCe: A high-precision proper motion study of the Cygnus OB2 association

    NASA Astrophysics Data System (ADS)

    Wright, Nicholas J.; Bouy, Herve; Drew, Janet E.; Sarro, Luis Manuel; Bertin, Emmanuel; Cuillandre, Jean-Charles; Barrado, David

    2016-08-01

    We present a high-precision proper motion study of 873 X-ray and spectroscopically selected stars in the massive OB association Cygnus OB2 as part of the DANCe project. These were calculated from images spanning a 15 yr baseline and have typical precisions <1 mas yr-1. We calculate the velocity dispersion in the two axes to be σ _α (c) = 13.0^{+0.8}_{-0.7} and σ _δ (c) = 9.1^{+0.5}_{-0.5} km s-1, using a two-component, two-dimensional model that takes into account the uncertainties on the measurements. This gives a three-dimensional velocity dispersion of σ3D = 17.8 ± 0.6 km s-1 implying a virial mass significantly larger than the observed stellar mass, confirming that the association is gravitationally unbound. The association appears to be dynamically unevolved, as evidenced by considerable kinematic substructure, non-isotropic velocity dispersions and a lack of energy equipartition. The proper motions show no evidence for a global expansion pattern, with approximately the same amount of kinetic energy in expansion as there is in contraction, which argues against the association being an expanded star cluster disrupted by process such as residual gas expulsion or tidal heating. The kinematic substructures, which appear to be close to virial equilibrium and have typical masses of 40-400 M⊙, also do not appear to have been affected by the expulsion of the residual gas. We conclude that Cyg OB2 was most likely born highly substructured and globally unbound, with the individual subgroups born in (or close to) virial equilibrium, and that the OB association has not experienced significant dynamical evolution since then.

  14. Close binary systems in OB-associations regions. V. the star V456 Cyg in direction of Cyg OB1

    NASA Astrophysics Data System (ADS)

    Zakirov, M. M.; Eshankulova, M. U.

    2006-10-01

    New UBVR photoelectric observations of the eclipsing variable star V456 Cyg of Algol type were obtained at the Maidanak Observatory in 1999-2003. The new ephemeris of the binary is: Min I=JDH2444911.3592(7) + {0.89119484 (14)d}\\cdot{E} + {0.15(1)}d\\cdot 10-9{\\cdot E2}. All of the light curves of the star V456 Cyg were solved by Lavrov's direct method, and elements of the photometric orbit were calculated. The results obtained in R-curve are different from data for other ones. We estimated the absolute basic parameters of the components: M1=2.0M⊙, M2 = 1.7M⊙, R1=1.7R⊙, R2 = 1.6R⊙, M1, bol = +1.7m, M2,bol = +2.5m. The components do not reach ZAMS in the H-R diagram and their age is 107 yrs. The distance for the star V456 Cyg is about 600 pc. The star lies in a well-maked OB-stars group separated by a distance of about 500 pc in the direction of the OB-association Cyg OB1.

  15. Study of Eclipsing Binary and Multiple Systems in OB Associations IV: Cas OB6 Member DN Cas

    NASA Astrophysics Data System (ADS)

    Bakış, V.; Bakış, H.; Bilir, S.; Eker, Z.

    2016-09-01

    An early-type, massive, short-period (Porb=2d.310951) eclipsing spectroscopic binary DN Cas has been re-visited with new spectral and photometric data. The masses and radii of the components have been obtained as M1=19.04± 0.07 M⊙, M2=13.73± 0.05 M⊙ and R1=7.22± 0.06 R⊙, R2=5.79± 0.06 R⊙, respectively. Both components present synchronous rotation (Vrot1=160 km s-1, Vrot2=130 km s-1) with their orbit. Orbital period analysis yielded a physically bound additional component in the system with a minimum mass of M3=0.88 M⊙ orbiting in an eccentric orbit (e = 0.37 ± 0.2) with an orbital period of P 12 = 42 ± 9 yr. High precision absolute parameters of the system allowed us to derive a distance to DN Cas as 1.7 ± 0.2 kpc which locates the system within the borders of the Cas OB6 association (d = 1.8 kpc). The space velocities and the age of DN Cas are in agreement with those of Cas OB6. The age of DN Cas (τ = 3-5 Myr) is found to be 1-2 Myr older than the embedded clusters (IC 1795, IC 1805, and IC 1848) in the Cas OB6 association, which implies a sequential star formation in the association.

  16. Long-term administration of PACAP receptor antagonist, PACAP(6-27), impairs glucose tolerance and insulin sensitivity in obese diabetic ob/ob mice.

    PubMed

    Green, Brian D; Irwin, Nigel; Cassidy, Roslyn S; Gault, Victor A; Flatt, Peter R

    2006-09-01

    Pituitary adenylate cyclase-activating peptide (PACAP) is a ubiquitous peptide of the glucagon superfamily that is involved in glucose homeostasis and regulation of insulin secretion. This study employed the PACAP receptor antagonist, PACAP(6-27) to evaluate the role of endogenous PACAP in genetic obesity-related diabetes and related metabolic abnormalities using ob/ob mice. Acute in vivo antagonistic potency of PACAP(6-27) was confirmed in ob/ob mice by blockade of the insulin-releasing action but not hyperglycaemia. In longer-term studies, ob/ob mice were given once daily injections of PACAP(6-27) or vehicle for 14 days. Feeding activity, body weight, basal plasma glucose and plasma insulin concentrations were not significantly affected by chronic PACAP(6-27) treatment. However, PACAP(6-27) treatment impaired glucose tolerance, insulin sensitivity and the glycaemic response to feeding. Plasma glucagon and lipids were unchanged. These observations indicate a role of endogenous PACAP for normal glucose homeostasis, but indicate a minor involvement in the regulation of insulin secretion in ob/ob mice.

  17. Beneficial Effects of Supplementation of the Rare Sugar "D-allulose" Against Hepatic Steatosis and Severe Obesity in Lep(ob)/Lep(ob) Mice.

    PubMed

    Itoh, Kouichi; Mizuno, Shodo; Hama, Sayuri; Oshima, Wataru; Kawamata, Miku; Hossain, Akram; Ishihara, Yasuhiro; Tokuda, Masaaki

    2015-07-01

    A rare sugar, D-allulose (also called D-psicose), has recently been applied as a food supplement in view of controlling diabetes and obesity in Japan. D-allulose has been proven to have unique effects against hyperglycemia and hyperlipidemia in a number of studies using several species of rats and mice. However, the antiobesity effects of D-allulose have not yet been assessed in Lep(ob)/Lep(ob) (ob/ob) mice. Therefore, this study explored the dietary supplemental effects of this sugar in leptin-deficient ob/ob mice. Consequently, the subchronic ingestion of D-allulose in ob/ob mice for 15 wk significantly decreased the body and liver weights, and the loss of body weight was involved in the reduction of the total fat mass, including abdominal visceral fat, and not fat-free body mass, including muscle. Furthermore, D-allulose improved hepatic steatosis, as evaluated using hepatic histological studies and MRI. In the normal mice, none of these parameters were influenced by the single or long-term ingestion of D-allulose. These results indicate that dietary supplementation of D-allulose especially influences postprandial hyperglycemia and obesity-related hepatic steatosis, without exercise therapy or dietary restriction. Therefore, D-allulose may be useful as a supplement for preventing and improving obesity and obesity-related disorders.

  18. Hepatic Macrosteatosis Is Partially Converted to Microsteatosis by Melatonin Supplementation in ob/ob Mice Non-Alcoholic Fatty Liver Disease

    PubMed Central

    Lavazza, Antonio; Golic, Igor; Aleksic, Marija; Korac, Aleksandra; Rodella, Luigi Fabrizio; Rezzani, Rita

    2016-01-01

    Background Obesity is a common risk factor for non-alcoholic fatty liver disease (NAFLD). Currently, there are no specific treatments against NAFLD. Thus, examining any molecule with potential benefits against this condition emerged melatonin as a molecule that influences metabolic dysfunctions. The aim of this study was to determine whether melatonin would function against NAFDL, studying morphological, ultrastuctural and metabolic markers that characterize the liver of ob/ob mice. Methods Lean and ob/ob mice were supplemented with melatonin in the drinking water for 8 weeks. Histology and stereology were performed to assess hepatic steatosis and glycogen deposition. Ultrastructural features of mitochondria, endoplasmic reticulum (ER) and their juxtapositions were evaluated in livers of all experimental groups. Furthermore, hepatic distribution and expression of markers of ER and mitochondria (calnexin, ATP sintase β, GRP78 and CHOP) and metabolic dysfunction (RPB4, β-catenin) and cellular longevity (SIRT1) were analyzed. Results Melatonin significantly reduced glycemia, identified also by a decrease of hepatic RBP4 expression, reversed macrosteatosis in microsteatosis at the hepatic pericentral zone, enlarged ER-mitochondrial distance and ameliorated the morphology and organization of these organelles in ob/ob mouse liver. Furthermore, in ob/ob mice, calnexin and ATP synthase β were partially restored, GRP78 and CHOP decreased in periportal and midzonal hepatocytes and β-catenin expression was, in part, restored in peripheral membranes of hepatocytes. Melatonin supplementation to ob/ob mice improves hepatic morphological, ultrastructural and metabolic damage that occurs as a result of NAFLD. Conclusions Melatonin may be a potential adjuvant treatment to limit NAFLD and its progression into irreversible complications. PMID:26824477

  19. Determining OBS Instrument Orientations: A Comparison of Algorithms

    NASA Astrophysics Data System (ADS)

    Doran, A. K.; Laske, G.

    2015-12-01

    The alignment of the orientation of the horizontal seismometer components with the geographical coordinate system is critical for a wide variety of seismic analyses, but the traditional deployment method of ocean bottom seismometers (OBS) precludes knowledge of this parameter. Current techniques for determining the orientation predominantly rely on body and surface wave data recorded from teleseismic events with sufficiently large magnitudes. Both wave types experience lateral refraction between the source and receiver as a result of heterogeneity and anisotropy, and therefore the arrival angle of any one phase can significantly deviate from the great circle minor arc. We systematically compare the results and uncertainties obtained through current determination methods, as well as describe a new algorithm that uses body wave, surface wave, and differential pressure gauge data (where available) to invert for horizontal orientation. To start with, our method is based on the easily transportable computer code of Stachnik et al. (2012) that is publicly available through IRIS. A major addition is that we utilize updated global dispersion maps to account for lateral refraction, as was done by Laske (1995). We also make measurements in a wide range of frequencies, and analyze surface wave trains of repeat orbits. Our method has the advantage of requiring fewer total events to achieve high precision estimates, which is beneficial for OBS deployments that can be as short as weeks. Although the program is designed for the purpose of use with OBS instruments, it also works with standard land installations. We intend to provide the community with a program that is easy to use, requires minimal user input, and is optimized to work with data cataloged at the IRIS DMC.

  20. OBS FOMAR POOL: Gibraltar and ALERTES-RIM experiments.

    NASA Astrophysics Data System (ADS)

    Pazos, Antonio; Martín Davila, Jose; Buforn, Elisa; Cabieces, Roberto; Santos, Jose; Sandoval, Nicolas; Roca, Antoni; Dahm, Torsten

    2016-04-01

    The Eurasian-African plate boundary crosses the called "Ibero-Maghrebian" region from the San Vicente Cape (SW Portugal) to Tunisia including the south Iberia, Alboran Sea, and northern of Morocco and Algeria. The low convergence rate at this plate boundary produces a continuous moderate seismic activity of low magnitude and shallow depth, where the occurrence of large earthquakes is separated by long time intervals, even with associated tsunamis, like the 1755 Lisbon earthquake. In this region, there are also intermediate and very deep earthquakes. Due to the fact that part of the seismic activity is located at marine areas, and also because of the poor geographic azimuthal coverage at some zones provided by the land stations (specially in the SW of the San Vicente Cape area), Royal Spanish Navy Observatory (ROA) acquired three "LOSTERN" broad band (CMG-40T sensors) OBS, manufactured by KUM (Kiel, Germany), and, more recently (2014), the Complutense University of Madrid (UCM) acquired another three with Trillium 120 sensors. All of them conform the OBS FOMAR pool. Since January to November 2014, the FOMAR pool has been deployed along the Gibraltar strait (Gibraltar experiment), in collaboration with SECEGSA (Spanish society to study the fix communication through the Gibraltar Strait), to study the local microseismicity in the Gibraltar strait area. Also, since September 2015, the FOMAR pool has been deployed for 8 months in SW of the San Vicente Cape with an hexagonal array configuration as a part of ALERTES-RIM project. In this work the some preliminary results of the Gibraltar strait and ALERTES-RIM OBS experiment are shown.

  1. Development of Hydrophone and Its Aapplications Use in OBS

    NASA Astrophysics Data System (ADS)

    Lin, C. R.; Kuo, B. Y.; Wang, C. C.; Chang, H. K.; Jang, J. P.

    2014-12-01

    The seismic wave is translated to T-wave when earthquakes occur below seafloor with a traveling speed of 1500 m/s in the SOFAR channel which centers roughly at 1000 m water depths (Tolstoy and Ewing, 1950). Many studies have shown that hydrophone can be set up in the SOFAR channel to collect acoustic data to investigate plate movement (Fox and Dziak, 1999), seismisity (Fox et.al, 2001), characteristic of T-wave (Park et.al, 2001), seafloor volcanism (Nicolas, 1989), among others. Institute of Earth Sciences of Academia Sinica has been collaborating with Taiwan Ocean Research Institute (TORI) and the Institute of Undersea Technology (IUT) of the National Sun Yat-sen University (NSYSU) to succefully build a new wide-band OBS (Yardbird). We hope that Yardbird is not only an OBS but also a multi-function underwater recording plotform. Therefor we are developing a low-power consumption, inexpensive hydrophone to catch acoustic signals. The protoypte of it has passed a series of tests and got some seismic seafloor data. This paper describes the design goal of hydrophone, component specifications, field data analyzed, and discusses the future directions of instrument development. Keywords: T-wave; Hydrophone; OBS; acoustic signal Referance: 1 Fox, C. G. and R. P. Dziak, Intenal deformation of the Gorda Plate observedb y hydroacoustimc onitoring, J . Geophys Res., 104, 17603-17615, 1999. 2 Fox, C. G., H. Matsumoto and T.K.Lau, Monitoring Pacific Ocean seismicity from an autonomous hydrophone array. , J . Geophys. Res., 106,4183-4206, 2001. 3 Nicolas, A., Structures of ophiolites and dynamics of oceanic lithosphere. Dordrecht ; Boston : Kluwer Academic Publishers, 1989. 4. Park, M., R.I. Odom, and D.J. Soukup (2001). Modal scattering: a key to understanding oceanic T-waves, Geophys. Res. Lett. 28, 3401-3404. 5. Tolstoy, I. and M. Ewing (1950). The T phase of shallow-focus earthquakes, Bull. Seismol. Soc. Am. 40, 25-51.

  2. A New Subdwarf-OB Pulsator J23341+4622

    NASA Astrophysics Data System (ADS)

    Pakštiene, E.; Qvam, J. K. T.; Østensen, R. H.; Telting, J. H.

    2014-12-01

    A new sdOB variable star, J23341+4622 (SDSS J233406.10+462249.3), was discovered during photometric observations with the Nordic Optical Telescope (La Palma). We found its main pulsation frequency at 7422(±9) μHz with an amplitude of 4.5(±0.5) mma. The star is possibly a complex pulsator, as we found another significant peak at 7759(±11) μHz with an amplitude of 2.0(±0.3) mma and a possible subharmonic of the main frequency at 3508 μHz with an amplitude of 2.3 mma.

  3. The effect of leptin replacement on sleep-disordered breathing in the leptin-deficient ob/ob mouse.

    PubMed

    Pho, H; Hernandez, A B; Arias, R S; Leitner, E B; Van Kooten, S; Kirkness, J P; Schneider, H; Smith, P L; Polotsky, V Y; Schwartz, A R

    2016-01-01

    Obese leptin-deficient (ob/ob) mice demonstrate defects in upper airway structural and neuromuscular control. We hypothesized that these defects predispose to upper airway obstruction during sleep, and improve with leptin administration. High-fidelity polysomnographic recordings were conducted to characterize sleep and breathing patterns in conscious, unrestrained ob/ob mice (23 wk, 67.2 ± 4.1 g, n = 13). In a parallel-arm crossover study, we compared responses to subcutaneous leptin (1 μg/h) vs. vehicle on respiratory parameters during NREM and REM sleep. Upper airway obstruction was defined by the presence of inspiratory airflow limitation (IFL), as characterized by an early inspiratory plateau in airflow at a maximum level (V̇Imax) with increasing effort. The severity of upper airway obstruction (V̇Imax) was assessed along with minute ventilation (V̇E), tidal volume (VT), respiratory rate (RR), inspiratory duty cycle, and mean inspiratory flow at each time point. IFL occurred more frequently in REM sleep (37.6 ± 0.2% vs. 1.1 ± 0.0% in NREM sleep, P < 0.001), and leptin did not alter its frequency. V̇Imax (3.7 ± 1.1 vs. 2.7 ± 0.8 ml/s, P < 0.001) and V̇E increased (55.4 ± 22.0 vs. 39.8 ± 16.4 ml/min, P < 0.001) with leptin vs. vehicle administration. The increase in V̇E was due to a significant increase in VT (0.20 ± 0.06 vs. 0.16 ± 0.05 ml, P < 0.01) rather than RR. Increases in V̇E were attributable to increases in mean inspiratory flow (2.5 ± 0.8 vs. 1.8 ± 0.6 ml/s, P < 0.001) rather than inspiratory duty cycle. Similar increases in V̇E and its components were observed in non-flow-limited breaths during NREM and REM sleep. These responses suggest that leptin stabilized pharyngeal patency and increased drive to both the upper airway and diaphragm during sleep.

  4. The Seismic Broad Band Western Mediterranean (wm) Network and the Obs Fomar Pool: Current state and Obs activities.

    NASA Astrophysics Data System (ADS)

    Pazos, Antonio; Davila, Jose Martin; Buforn, Elisa; Bezzeghoud, Mourad; Harnafi, Mimoun; Mattesini, Mauricio; Caldeira, Bento; Hanka, Winfried; El Moudnib, Lahcen; Strollo, Angelo; Roca, Antoni; Lopez de Mesa, Mireya; Dahm, Torsten; Cabieces, Roberto

    2016-04-01

    The Western Mediterranean (WM) seismic network started in 1996 as an initiative of the Royal Spanish Navy Observatory (ROA) and the Universidad Complutense de Madrid (UCM), with the collaboration of the GeoForschungsZentrum (GFZ) of Potsdam. A first broad band seismic station (SFUC) was installed close to Cádiz (South Spain). Since then, additional stations have been installed in the Ibero-Moghrebian region. In 2005, the "WM" code was assigned by the FDSN and new partners were jointed: Evora University (UEVO, Portugal), the Scientifique Institute of Rabat (ISRABAT, Morocco), and GFZ. Now days, the WM network is composed by 15 BB stations, all of them with Streckaisen STS-2 or STS-2.5 sensors, Quanterra or Earthdata digitizers and SeiscomP. Most them have co-installed a permanent geodetic GPS stations, and some them also have an accelerometer. There are 10 stations deployed in Spanish territory (5 in the Iberian peninsula, 1 in Balearic islands and 4 in North Africa Spanish places) with VSAT or Internet communications, 2 in Portugal (one of them without real time), and 3 in Morocco (2 VSAT and 1 ADSL). Additionally, 2 more stations (one in South Spain and one in Morocco) will be installed along this year. Additionally ROA has deployed a permanent real time VBB (CMG-3T: 360s) station at the Alboran Island. Due to the fact that part of the seismic activity is located at marine areas, and also because of the poor geographic azimuthal coverage at some zones provided by the land stations (specially in the SW of the San Vicente Cape area), ROA and UCM have acquired six broad band "LOBSTERN" OBS, manufactured by KUM (Kiel, Germany), conforming the OBS FOMAR pool. Three of them with CMG-40T sensor and the other with Trillium 120. These OBS were deployed along the Gibraltar strait since January to November 2014 to study the microseismicity in the Gibraltar strait area. In September 2015 FOMAR network has been deployed in SW of the San Vicente Cape for 8 months as a part of

  5. OT1_mrubio_1: Clumping in OB-star winds

    NASA Astrophysics Data System (ADS)

    Rubio, M.

    2010-07-01

    Massive stars, their nature and evolution, play a important role at all stages of the Universe. Through their radiatively driven winds they influence on the dynamics and energetics of the interstellar medium. The winds of OB stars are the most studied case. Commonly, the mass-loss rates of luminous OB stars are inferred from several types of measurements, the strengths of UV P Cygni lines, H-alpha emission and radio and FIR continuum emission. Recent evidence indicates that currently accepted mass-loss rates may need to be revised downwards when small-scale density inhomogeneities (clumping) are taken into account. We argue that only a consistent treatment of ALL possible diagnostics, scanning different parts of the winds, and analyzed by means of state of the art model atmospheres, will permit the determination of true mass-loss rates. To this end we have assembled a variety of multi-wavelength data, but one crucial observational set is missing: far-IR diagnostics of free-free emission, which uniquely constrain the clumping properties of the wind at intermediate heights. We propose, therefore, to use PACS photometric mode to fill this crucial gap, studying the 70 and 110 micron fluxes of a carefully selected sample of 29 O4-B8 stars. These observations will provide the missing information to derive the clumping properties of the entire outflow, to understand the wind physics, and to obtain reliable massloss rates.

  6. OT2_mrubio_2: Clumping in OB-star winds

    NASA Astrophysics Data System (ADS)

    Rubio, M.

    2011-09-01

    Massive stars, their nature and evolution, play a important role at all stages of the Universe. Through their radiatively driven winds they influence on the dynamics and energetics of the interstellar medium. The winds of OB stars are the most studied case. Commonly, the mass-loss rates of luminous OB stars are inferred from several types of measurements, the strengths of UV P Cygni lines, H-alpha emission and radio and FIR continuum emission. Recent evidence indicates that currently accepted mass-loss rates may need to be revised downwards when small-scale density inhomogeneities (clumping) are taken into account. We argue that only a consistent treatment of ALL possible diagnostics, scanning different parts of the winds, and analyzed by means of state of the art model atmospheres, will permit the determination of true mass-loss rates. To this end we have assembled a variety of multi-wavelength data, but one crucial observational set is missing: far-IR diagnostics of free-free emission, which uniquely constrain the clumping properties of the wind at intermediate heights. We propose, therefore, to use PACS photometric mode to fill this crucial gap, studying the 70 and 110 micron fluxes of a carefully selected sample of 29 O4-B8 stars. These observations will provide the missing information to derive the clumping properties of the entire outflow, to understand the wind physics, and to obtain reliable massloss rates.

  7. A new Shallow Water Cabled OBS System off California

    NASA Astrophysics Data System (ADS)

    Rademacher, Horst; Pearcey, Chris; Mangano, Giorgio; Guralp, Cansun; Pearce, Nathan

    2014-05-01

    During the summer and fall of 2013 we installed a turnkey cabled network of four combination broadband velocity/acceleration ocean bottom sensors (OBS) on the sea floor near Point Buchon in the Northeastern Pacific Ocean off the coast of Central California. We implemented a novel network design by daisy-chaining the instruments to one single multistranded cable. The signals of each station are digitized in-situ and then transmitted via dedicated optical fiber links inside the cable to a shore station. From there they are fed in real time via a cell phone modem into several seismic networks in California. The goal of this dense network is to monitor the microseismicity of two offshore faults running parallel to the strike of the San Andreas Fault. However, because the network is installed in rather shallow water near the coast, the action of waves and swell at the sea surface affect the sensor registrations much stronger as compared to the typical deep water installation of OBS equipment. We will report about the challenges of installing and maintaining the network and present some initial results.

  8. Analysis of methane biodegradation by Methylosinus trichosporium OB3b

    PubMed Central

    Rodrigues, Andréa dos Santos; Salgado, Belkis Valdman e Andréa Medeiros

    2009-01-01

    The microbial oxidation of methane in the atmosphere is performed by methanotrophic bacteria that use methane as a unique source of carbon and energy. The objective of this work consisted of the investigation of the best conditions of methane biodegradation by methanotrophic bacteria Methylosinus trichosporium OB3b that oxidize it to carbon dioxide, and the use of these microorganisms in monitoring methods for methane. The results showed that M. trichosporium OB3b was capable to degrade methane in a more effective way with an initial microorganism concentration of 0.0700 g.L-1, temperature of 30ºC, pH 6.5 and using 1.79 mmol of methane. In these same conditions, there was no bacterial growth when 2.69 mmol of methane was used. The specific rate of microorganism growth, the conversion factor, the efficiency and the volumetric productivity, for the optimized conditions of biodegradation were, respectively, 0.0324 h-1, 0.6830 gcells/gCH4, 73.73% and 2.7732.10-3 gcells/L.h. The final product of methane microbiological degradation, carbon dioxide, was quantified through the use of a commercial electrode, and, through this, the grade of methane conversion in carbon dioxide was calculated. PMID:24031362

  9. A novel technique for resolving burst contention in OBS networks

    NASA Astrophysics Data System (ADS)

    Garg, Amit Kumar; Kaler, R. S.

    2010-03-01

    In this article, in order to resolve burst contention (burst dropping), a new scheme for an optical burst switching (OBS) network has been proposed which is based on the integration of wavelength selection and burst assignment. The proposed scheme provides proportional differentiated services in bufferless OBS networks by dynamically assigning more and longer periods of wavelengths to higher priority classes. In addition, burst head packets (BHPs) are buffered electrically so that fiber delay lines are unnecessary at core nodes. As a result, BHP of a lower priority class is buffered at the core router when it cannot find an available wavelength. It has an opportunity to reschedule its burst to the wavelengths that have been assigned to higher priority classes but have not yet been reserved. The proposed integrated scheme not only provides proportional differentiated services but also achieves lower average dropping probability without any preemption or segmentation mechanisms. Compared with existing approaches, the proposed integrated scheme does not need to generate any special packets and needs to maintain only a few parameters at core nodes.The proposed scheme has several attractive features such as fast, simple implementation and improved burst dropping performance. Extensive simulation results have been used to demonstrate the effectiveness of the proposed scheme in comparison to traditional schemes.

  10. Young Stars in the Cygnus OB2 Association

    NASA Astrophysics Data System (ADS)

    Hartigan, Patrick; Cleeves, Ilse

    2009-08-01

    Cygnus OB2 is by far the dominant region of massive star formation within 2-3 kpc of the Sun, but its stellar content is almost completely unknown owing to large amounts of visual extinction. Using NEWFIRM last fall we surveyed a large area of over two square degrees centered on the main cluster of O and B stars, and found the central part of the cluster to be teeming with at least several hundred, and probably over a thousand stars with near-IR excesses typical of circumstellar disks. With this proposal we aim to begin the process of acquiring spectral types for the entire sample of IR-excess and X-ray bright stars. This census will lead to masses, ages, and accretion rates for each object. With over 100 O stars, Cyg OB2 dwarfs the young clusters in Orion, and promises to provide a truly unique large sample of young stars that can address many of the major outstanding questions of star formation, such as IMF variations, binarity, triggering, mass segregation, accretion history, and disk evolution in a statistically significant way.

  11. Reduction of obesity, as induced by leptin, reverses endothelial dysfunction in obese (Lep(ob)) mice

    NASA Technical Reports Server (NTRS)

    Winters, B.; Mo, Z.; Brooks-Asplund, E.; Kim, S.; Shoukas, A.; Li, D.; Nyhan, D.; Berkowitz, D. E.

    2000-01-01

    Obesity is a major health care problem and is associated with significant cardiovascular morbidity. Leptin, a neuroendocrine hormone released by adipose tissue, is important in modulating obesity by signaling satiety and increasing metabolism. Moreover, leptin receptors are expressed on vascular endothelial cells (ECs) and mediate angiogenesis. We hypothesized that leptin may also play an important role in vasoregulation. We investigated vasoregulatory mechanisms in the leptin-deficient obese (ob/ob) mouse model and determined the influence of leptin replacement on endothelial-dependent vasorelaxant responses. The direct effect of leptin on EC nitric oxide (NO) production was also tested by using 4, 5-diaminofluorescein-2 diacetate staining and measurement of nitrate and nitrite concentrations. Vasoconstrictor responses to phenylephrine, norepinephrine, and U-46619 were markedly enhanced in aortic rings from ob/ob mice and were modulated by NO synthase inhibition. Vasorelaxant responses to ACh were markedly attenuated in mesenteric microvessels from ob/ob mice. Leptin replacement resulted in significant weight loss and reversal of the impaired endothelial-dependent vasorelaxant responses observed in ob/ob mice. Preincubation of ECs with leptin enhanced the release of NO production. Thus leptin-deficient ob/ob mice demonstrate marked abnormalities in vasoregulation, including impaired endothelial-dependent vasodilation, which is reversed by leptin replacement. These findings may be partially explained by the direct effect of leptin on endothelial NO production. These vascular abnormalities are similar to those observed in obese, diabetic, leptin-resistant humans. The ob/ob mouse may, therefore, be an excellent new model for the study of the cardiovascular effects of obesity.

  12. Variability Survey of Massive Stars in OB-Associations: Preliminary Results on the Cygnus Region

    NASA Astrophysics Data System (ADS)

    Laur, J.; Tuvikene, T.; Eenmäe, T.; Kolka, I.; Leedjärv, L.

    We present V- and I-passband photometry of massive stars in the Cyg OB1 and Cyg OB2 associations, based on about 80 observing nights spanning 300 days in the 2011 season. The variability of 22 supergiants and 48 OB-stars with luminosity classes III--V is analyzed. We report two new variable OB stars and 15 variable supergiants of which four are new discoveries. The light variations of Schulte 12 are interpreted as microvariability. We also present light curves of the red supergiants BC Cyg and BI Cyg which exhibit brightness drop of more than 0.4 mag during the season.

  13. Anti-obesity activity of diglyceride containing conjugated linoleic acid in C57BL/6J ob/ob mice

    PubMed Central

    Hue, Jin-Joo; Lee, Ki Nam; Jeong, Jae-Hwang; Lee, Sang-Hwa; Lee, Young Ho; Jeong, Seong-woon; Nam, Sang Yoon; Yun, Young Won

    2009-01-01

    This study was to investigate the anti-obesity effects of diglyceride (DG)-conjugated linoleic acid (CLA) containing 22% CLA as fatty acids in C57BL/6J ob/ob male mice. There were four experimental groups including vehicle control, DG, CLA, and DG-CLA. The test solutions of 750 mg/kg dose were orally administered to the mice everyday for 5 weeks. CLA treatments significantly decreased mean body weight in the obese mice throughout the experimental period compared to the control (p < 0.01). All test solutions significantly decreased the levels of triglyceride, glucose and free fatty acids in the serum compared with control (p < 0.05). The levels of total cholesterol were also significantly reduced in DG and DG-CLA groups compared with the control group (p < 0.05). CLA significantly decreased weights of renal and epididymal fats compared with the control (p < 0.05). DG and DG-CLA also significantly decreased the epididymal fat weights compared with the control (p < 0.05). A remarkable decrease in the number of lipid droplets and fat globules was observed in the livers of mice treated with DG, CLA, and DG-CLA compared to control. Treatments of DG and CLA actually increased the expression of peroxisome proliferator-activated receptor gamma. These results suggest that DG-CLA containing 22% CLA have a respectable anti-obesity effect by controlling serum lipids and fat metabolism. PMID:19687618

  14. Dietary Cooked Navy Beans and Their Fractions Attenuate Colon Carcinogenesis in Azoxymethane-Induced Ob/Ob Mice

    PubMed Central

    Bobe, Gerd; Barrett, Kathleen G.; Mentor-Marcel, Roycelynn A.; Saffiotti, Umberto; Young, Matthew R.; Colburn, Nancy H.; Albert, Paul S.; Bennink, Maurice R.; Lanza, Elaine

    2008-01-01

    Based on the protective effects of cooked dry bean consumption in a human intervention study, we evaluated which fraction of cooked dry beans is responsible for its cancer-preventive effects. Cooked navy beans (whole beans), the insoluble fraction (bean residue) or soluble fraction of the 60% (vol:vol) ethanol extract of cooked navy beans (bean extract), or a modified AIN-93G diet (16.6% fat including 12.9% lard) as control diet were fed to 160 male obese ob/ob mice after 2 azoxymethane injections. In comparison to control-fed mice, dysplasia, adenomas, or adenocarcinomas were detected in fewer mice on either bean fraction diet (percent reduction from control: whole beans 54%, P = 0.10; bean residue 81%, P = 0.003 ; bean extract 91%, P = 0.007) , and any type of colon lesions, including focal hyperplasia, were found in fewer mice on each of the 3 bean diets percent reduction from control: whole bean 56%, P = 0.04; bean residue 67%, P = 0.01; bean extract 87%, P = 0.0003. These results suggest that both the soluble and the insoluble fraction of the extract contribute to the cancer-protective effect of cooked navy beans. PMID:18444172

  15. Cosmography of OB stars in the solar neighbourhood

    NASA Astrophysics Data System (ADS)

    Bouy, H.; Alves, J.

    2015-12-01

    We construct a 3D map of the spatial density of OB stars within 500 pc from the Sun using the Hipparcos catalogue and find three large-scale stream-like structures that allow a new view on the solar neighbourhood. The spatial coherence of these blue streams and the monotonic age sequence over hundreds of parsecs suggest that they are made of young stars, similar to the young streams that are conspicuous in nearby spiral galaxies. The three streams are 1) the Scorpius to Canis Majoris stream, covering 350 pc and 65 Myr of star formation history; 2) the Vela stream, encompassing at least 150 pc and 25 Myr of star formation history; and 3) the Orion stream, including not only the well-known Orion OB1abcd associations, but also a large previously unreported foreground stellar group lying only 200 pc from the Sun. The map also reveals a remarkable and previously unknown nearby OB association, between the Orion stream and the Taurus molecular clouds, which might be responsible for the observed structure and star formation activity in this cloud complex. This new association also appears to be the birthplace of Betelgeuse, as indicated by the proximity and velocity of the red giant. If this is confirmed, it would solve the long-standing puzzle of the origin of Betelgeuse. The well-known nearby star-forming low-mass clouds, including the nearby T and R associations Lupus, Cha, Oph, CrA, Taurus, Vela R1, and various low-mass cometary clouds in Vela and Orion, appear in this new view of the local neighbourhood to be secondary star formation episodes that most likely were triggered by the feedback from the massive stars in the streams. We also recover well-known star clusters of various ages that are currently cruising through the solar neighbourhood. Finally, we find no evidence of an elliptical structure such as the Gould belt, a structure we suggest is a 2D projection effect, and not a physical ring. Table 3 is available in elctronic form at http://www.aanda.org

  16. The Ob Estuary (Kara Sea) Coastal Dynamics Interannual Variability Assessment

    NASA Astrophysics Data System (ADS)

    Kopa-Ovdienko, N.; Volobueva, N.; Ogorodov, S.

    2012-04-01

    There are several promising gas fields in the Ob Estuary. For their development comprehensive research, including coastal dynamics assessment, is required. To estimate current and speak about future coastal dynamics rates we need to investigate its interannual variability connecting it with variability of major coastal dynamics factors. It is known that in this region one of the main coastal dynamics factors is wave action, which, in turn, depends on wind velocity and direction. Wind data for ice-free period were derived from nearby hydro-meteorological stations. The research was conducted for two sections of the Ob Estuary coast. One section is located on the eastern coast of the estuary (Taz peninsula); the other is located on the western one (Yamal peninsula). Each of these sections is 10 km length. For key-sites of the coast wave-dangerous rhumbs were determined. For ice-free period of each year accumulated summer storm duration (ASSD) - number of hours with strong winds (≥10 m/s) from wave-dangerous directions - was calculated for both sections of coast. Supposing that coast retreat rate is proportional to number of hours with strong winds from wave-dangerous rhumbs, we can approximately assess interannual variability of coast retreat rate. Our research revealed that: 1)There are significant (from hours to a few hundreds of hours) differences in ASSD from year to year due to short ice-free period and high variability of wind velocity and direction. So, we can expect sharp interannual differences in coastal retreat rate. 2)The duration of strong winds from wave-dangerous rhumbs during ice-free period is more on the eastern coast of the estuary than on the western. This goes from the predominance of northern and northwestern winds during ice-free period. These winds cause waves leading to coastal erosion on the eastern coast of estuary and don't cause such waves on the western one. However, we can't draw conclusions about the comparative rates of coastal

  17. IFN-γ secretion in gut of Ob/Ob mice after vertical sleeve gastrectomy and its function in weight loss mechanism.

    PubMed

    Du, Jin-Peng; Wang, Geng; Hu, Chao-Jie; Wang, Qing-Bo; Li, Hui-Qing; Xia, Wen-Fang; Shuai, Xiao-Ming; Tao, Kai-Xiong; Wang, Guo-Bin; Xia, Ze-Feng

    2016-06-01

    Vertical sleeve gastrectomy (VSG) is becoming more and more popular among the world. Despite its dramatic efficacy, however, the mechanism of VSG remains largely undetermined. This study aimed to test interferon (IFN)-γ secretion n of mesenteric lymph nodes in obese mice (ob/ob mice), a model of VSG, and its relationship with farnesoid X receptor (FXR) expression in the liver and small intestine, and to investigate the weight loss mechanism of VSG. The wild type (WT) mice and ob/ob mice were divided into four groups: A (WT+Sham), B (WT+VSG), C (ob/ob+Sham), and D (ob/ob+VSG). Body weight values were monitored. The IFN-γ expression in mesenteric lymph nodes of ob/ob mice pre- and post-operation was detected by flow cytometry (FCM). The FXR expression in the liver and small intestine was detected by Western blotting. The mouse AML-12 liver cells were stimulated with IFN-γ at different concentrations in vitro. The changes of FXR expression were also examined. The results showed that the body weight of ob/ob mice was significantly declined from (40.6±2.7) g to (27.5±3.8) g on the 30th day after VSG (P<0.05). At the same time, VSG induced a higher level secretion of IFN-γ in mesenteric lymph nodes of ob/ob mice than that pre-operation (P<0.05). The FXR expression levels in the liver and small intestine after VSG were respectively 0.97±0.07 and 0.84±0.07 fold of GAPDH, which were significantly higher than pre-operative levels of 0.50±0.06 and 0.48±0.06 respectively (P<0.05). After the stimulation of AML-12 liver cells in vitro by different concentrations of IFN-γ (0, 10, 25, 50, 100, and 200 ng/mL), the relative FXR expression levels were 0.22±0.04, 0.31±0.04, 0.39±0.05, 0.38±0.05, 0.56±0.06, and 0.35±0.05, respectively, suggesting IFN-γ could distinctly promote the FXR expression in a dose-dependent manner in comparison to those cells without IFN-γ stimulation (P<0.05). It was concluded that VSG induces a weight loss in ob/ob mice by increasing IFN

  18. New Hα stars. Cyg OB7 region. I.

    NASA Astrophysics Data System (ADS)

    Melikian, N. D.; Karapetian, A. A.

    2010-12-01

    Preliminary results from a search for emission stars in the neighborhood of Cyg OB7 are reported. A new region of size 14×14 arc min lies 12 arc min to the south of HH 448. 17 new objects have been found, of which one is related to a nebula with an interesting shape and, apparently, the characteristics of a cometary nebula. Inside the nebula there are 4 faint, compact formations with very high proper motions. The spectrum of a star shows that it is of spectral class K9-M0 and is a T Tau type star at a distance of 220 pc. Most of the discovered stars with a strong or intermediate Ha emission line intensity are presumably also T Tau stars. This region appears to be a continuation of the T association around HH 448.

  19. New Emission Stars in B Cyg OB7

    NASA Astrophysics Data System (ADS)

    Melikian, N. D.; Karapetian, A. A.; Gomez, J.

    2016-12-01

    This is a continuation of a search for and study of emission objects in known dark clouds and star formation regions. New results are presented from a search for emission stars in the region of Cyg OB7 where 36 new emission stars have been discovered previously. The current observations were made adjacent to previously studied regions in the vicinity of the object HH 448. 26 new emission stars were found in three small regions with a combined area of 0.11 sq. deg. On an (H-K)-(J-H) two-color diagram these stars lie among the classical T Tau stars (CTTS) and T Tau stars with weak lines (WTTS). A strong change in brightness was recorded for one of the emission stars.

  20. Quantitative spectroscopy of OB stars: from dwarfs to supergiants

    NASA Astrophysics Data System (ADS)

    Przybilla, N.; Nieva, M. F.; Firnstein, M.; Butler, K.

    2013-02-01

    We discuss recent progress made in the spectral modelling of OB stars from the main sequence to evolved phases as BA-type supergiants. Non-LTE line-formation computations can now reproduce observed spectra over the entire optical and near-IR wavelength range with high confidence, facilitating stellar atmospheric parameters and elemental abundances to be determined at high accuracy and precision. An overview is given how the fundamental stellar parameters of single stars determined in our new approach compare to high-precision data derived from detached eclipsing massive binary stars. Finally, the observational constraints for a sample of Galactic objects are put in context with state-of-the-art evolution models for rotating massive stars.

  1. Effects of CP-900691, a novel peroxisome proliferator-activated receptor α, agonist on diabetic nephropathy in the BTBR ob/ob mouse.

    PubMed

    Askari, Bardia; Wietecha, Tomasz; Hudkins, Kelly L; Fox, Edward J; O'Brien, Kevin D; Kim, Jinkyu; Nguyen, Tri Q; Alpers, Charles E

    2014-08-01

    Piperidine-based peroxisome proliferator-activated receptor-α agonists are agents that are efficacious in improving lipid, glycemic, and inflammatory indicators in diabetes and obesity. This study sought to determine whether CP-900691 ((S)-3-[3-(1-carboxy-1-methyl-ethoxy)-phenyl]-piperidine-1-carboxylic acid 4-trifluoromethyl-benzyl ester; CP), a member of this novel class of agents, by decreasing plasma triglycerides, could prevent diabetic nephropathy in the Black and Tan, BRachyuric (BTBR) ob/ob mouse model of type 2 diabetes mellitus. Four-week old female BTBR WT and BTBR ob/ob mice received either regular chow or one containing CP (3 mg/kg per day) for 14 weeks. CP elevated plasma high-density lipoprotein, albuminuria, and urinary excretion of 8-epi PGF(2α), a product of the nonenzymatic metabolism of arachidonic acid and whose production is elevated in oxidative stress, in BTBR WT mice. In BTBR ob/ob mice, CP reduced plasma triglycerides and non-esterified fatty acids, fasting blood glucose, body weight, and plasma interleukin-6, while concomitantly improving insulin resistance. Despite these beneficial metabolic effects, CP had no effect on elevated plasma insulin, 8-epi PGF(2α) excretion, and albuminuria, and surprisingly, did not ameliorate the development of diabetic nephropathy, having no effect on the accumulation of renal macrophages, glomerular hypertrophy, and increased mesangial matrix expansion. In addition, CP did not increase plasma high-density lipoprotein in BTBR ob/ob mice, while paradoxically increasing total cholesterol levels. These findings indicate that 8-epi PGF(2α), possibly along with hyperinsulinemia and inflammatory and dysfunctional lipoproteins, is integral to the development of diabetic nephropathy and should be considered as a potential target of therapy in the treatment of diabetic nephropathy.

  2. High aminopeptidase A activity contributes to blood pressure control in ob/ob mice by AT2 receptor-dependent mechanism.

    PubMed

    Morais, Rafael L; Hilzendeger, Aline M; Visniauskas, Bruna; Todiras, Mihail; Alenina, Natalia; Mori, Marcelo A; Araújo, Ronaldo C; Nakaie, Clovis R; Chagas, Jair R; Carmona, Adriana K; Bader, Michael; Pesquero, João B

    2017-03-01

    Obesity is assumed to be a major cause of human essential hypertension; however, the mechanisms responsible for weight-related increase in blood pressure (BP) are not fully understood. The prevalence of hypertension induced by obesity has grown over the years, and the role of the renin-angiotensin-aldosterone system (RAAS) in this process continues to be elucidated. In this scenario, the ob/ob mice are a genetic obesity model generally used for metabolic disorder studies. These mice are normotensive even though they present several metabolic conditions that predispose them to hypertension. Although the normotensive trait in these mice is associated with the poor activation of sympathetic nervous system by the lack of leptin, we demonstrated that ob/ob mice present massively increased aminopeptidase A (APA) activity in the circulation. APA enzyme metabolizes angiotensin (ANG) II into ANG III, a peptide associated with intrarenal angiotensin type 2 (AT2) receptor activation and induction of natriuresis. In these mice, we found increased ANG-III levels in the circulation, high AT2 receptor expression in the kidney, and enhanced natriuresis. AT2 receptor blocking and APA inhibition increased BP, suggesting the ANG III-AT2 receptor axis as a complementary BP control mechanism. Circulating APA activity was significantly reduced by weight loss independently of leptin, indicating the role of fat tissue in APA production. Therefore, in this study we provide new data supporting the role of APA in BP control in ob/ob mouse strain. These findings improve our comprehension about obesity-related hypertension and suggest new tools for its treatment.NEW & NOTEWORTHY In this study, we reported an increased angiotensin III generation in the circulation of ob/ob mice caused by a high aminopeptidase A activity. These findings are associated with an increased natriuresis found in these mice and support the role of renin-angiotensin-aldosterone system as additional mechanism regulating

  3. The PPAR-γ agonist, darglitazone, restores acute inflammatory responses to cerebral hypoxia–ischemia in the diabetic ob/ob mouse

    PubMed Central

    Kumari, Rashmi; Willing, Lisa B; Patel, Shyama D; Krady, J Kyle; Zavadoski, William J; Gibbs, E Michael; Vannucci, Susan J; Simpson, Ian A

    2010-01-01

    Diabetes is an increased risk factor for stroke and results in increased brain damage in experimental animals and humans. The precise mechanisms are unclear, but our earlier studies in the db/db mice suggested that the cerebral inflammatory response initiating recovery was both delayed and diminished in the diabetic mice compared with the nondiabetic db/+ mice. In this study, we investigated the actions of the peroxisome proliferator-activated receptor (PPAR)-γ agonist darglitazone in treating diabetes and promoting recovery after a hypoxic-ischemic (H/I) insult in the diabetic ob/ob mouse. Male ob/+ and ob/ob mice received darglitazone (1 mg/kg) for 7 days before induction of H/I. Darglitazone restored euglycemia and normalized elevated corticosterone, triglycerides, and very-low-density lipoprotein levels. Darglitazone dramatically reduced the infarct size in the ob/ob mice at 24 h of recovery compared with the untreated group (30±13% to 3.3±1.6%, n=6 to 8) but did not show any significant effect in the ob/+ mice. Microglial and astrocytic activation monitored by cytokine expression (interleukin-1β and tumor necrosis factor-α) and in situ hybridization studies (bfl1 and glial fibrillary acidic protein) suggest a biphasic inflammatory response, with darglitazone restoring the compromised proinflammatory response(s) in the diabetic mouse at 4 h but suppressing subsequent inflammatory responses at 8 and 24 h in both control and diabetic mice. PMID:19861974

  4. DUSTY OB STARS IN THE SMALL MAGELLANIC CLOUD. I. OPTICAL SPECTROSCOPY REVEALS PREDOMINANTLY MAIN-SEQUENCE OB STARS

    SciTech Connect

    Sheets, Holly A.; Bolatto, Alberto D.; Van Loon, Jacco Th.; Oliveira, Joana M.; Sandstrom, Karin; Simon, Joshua D.; Barba, Rodolfo H.

    2013-07-10

    We present the results of optical spectroscopic follow-up of 125 candidate main sequence OB stars in the Small Magellanic Cloud (SMC) that were originally identified in the S{sup 3}MC infrared imaging survey as showing an excess of emission at 24 {mu}m indicative of warm dust, such as that associated with a transitional or debris disks. We use these long-slit spectra to investigate the origin of the 24 {mu}m emission and the nature of these stars. A possible explanation for the observed 24 {mu}m excess, that these are emission line stars with dusty excretion disks, is disproven for the majority of our sources. We find that 88 of these objects are normal stars without line emission, with spectral types mostly ranging from late-O to early-B; luminosity classes from the literature for a sub-set of our sample indicate that most are main-sequence stars. We further identify 17 emission-line stars, 7 possible emission-line stars, and 5 other objects with forbidden-line emission in our sample. We discover a new O6 Iaf star; it exhibits strong He II 4686 A emission but relatively weak N III 4640 A emission which we attribute to the lower nitrogen abundance in the SMC. Two other objects are identified with planetary nebulae, one with a young stellar object, and two with X-ray binaries. To shed additional light on the nature of the observed 24 {mu}m excess we use optical and infrared photometry to estimate the dust properties of the objects with normal O and B star spectra and compare these properties to those of a sample of hot spots in the Galactic interstellar medium (ISM). We find that the dust properties of the dusty OB star sample resemble the properties of the Galactic sample of hot spots. Some may be runaway systems with bow-shocks resulting from a large velocity difference between star and ISM. We further investigate the nature of these dusty OB stars in a companion paper presenting mid-infrared spectroscopy and additional imaging.

  5. Leptin Administration Favors Muscle Mass Accretion by Decreasing FoxO3a and Increasing PGC-1α in ob/ob Mice

    PubMed Central

    Sáinz, Neira; Rodríguez, Amaia; Catalán, Victoria; Becerril, Sara; Ramírez, Beatriz; Gómez-Ambrosi, Javier; Frühbeck, Gema

    2009-01-01

    Absence of leptin has been associated with reduced skeletal muscle mass in leptin-deficient ob/ob mice. The aim of our study was to examine the effect of leptin on the catabolic and anabolic pathways regulating muscle mass. Gastrocnemius, extensor digitorum longus and soleus muscle mass as well as fiber size were significantly lower in ob/ob mice compared to wild type littermates, being significantly increased by leptin administration (P<0.001). This effect was associated with an inactivation of the muscle atrophy-related transcription factor forkhead box class O3 (FoxO3a) (P<0.05), and with a decrease in the protein expression levels of the E3 ubiquitin-ligases muscle atrophy F-box (MAFbx) (P<0.05) and muscle RING finger 1 (MuRF1) (P<0.05). Moreover, leptin increased (P<0.01) protein expression levels of peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), a regulator of muscle fiber type, and decreased (P<0.05) myostatin protein, a negative regulator of muscle growth. Leptin administration also activated (P<0.01) the regulators of cell cycle progression proliferating cell nuclear antigen (PCNA) and cyclin D1, and increased (P<0.01) myofibrillar protein troponin T. The present study provides evidence that leptin treatment may increase muscle mass of ob/ob mice by inhibiting myofibrillar protein degradation as well as enhancing muscle cell proliferation. PMID:19730740

  6. Leptin administration restores the altered adipose and hepatic expression of aquaglyceroporins improving the non-alcoholic fatty liver of ob/ob mice.

    PubMed

    Rodríguez, Amaia; Moreno, Natalia R; Balaguer, Inmaculada; Méndez-Giménez, Leire; Becerril, Sara; Catalán, Victoria; Gómez-Ambrosi, Javier; Portincasa, Piero; Calamita, Giuseppe; Soveral, Graça; Malagón, María M; Frühbeck, Gema

    2015-07-10

    Glycerol is an important metabolite for the control of lipid accumulation in white adipose tissue (WAT) and liver. We aimed to investigate whether exogenous administration of leptin improves features of non-alcoholic fatty liver disease (NAFLD) in leptin-deficient ob/ob mice via the regulation of AQP3 and AQP7 (glycerol channels mediating glycerol efflux in adipocytes) and AQP9 (aquaglyceroporin facilitating glycerol influx in hepatocytes). Twelve-week-old male wild type and ob/ob mice were divided in three groups as follows: control, leptin-treated (1 mg/kg/d) and pair-fed. Leptin deficiency was associated with obesity and NAFLD exhibiting an AQP3 and AQP7 increase in WAT, without changes in hepatic AQP9. Adipose Aqp3 and hepatic Aqp9 transcripts positively correlated with markers of adiposity and hepatic steatosis. Chronic leptin administration (4-weeks) was associated with improved body weight, whole-body adiposity, and hepatosteatosis of ob/ob mice and to a down-regulation of AQP3, AQP7 in WAT and an up-regulation of hepatic AQP9. Acute leptin stimulation in vitro (4-h) induced the mobilization of aquaglyceroporins towards lipid droplets (AQP3) and the plasma membrane (AQP7) in murine adipocytes. Our results show that leptin restores the coordinated regulation of fat-specific AQP7 and liver-specific AQP9, a step which might prevent lipid overaccumulation in WAT and liver in obesity.

  7. Leptin administration restores the altered adipose and hepatic expression of aquaglyceroporins improving the non-alcoholic fatty liver of ob/ob mice

    PubMed Central

    Rodríguez, Amaia; Moreno, Natalia R.; Balaguer, Inmaculada; Méndez-Giménez, Leire; Becerril, Sara; Catalán, Victoria; Gómez-Ambrosi, Javier; Portincasa, Piero; Calamita, Giuseppe; Soveral, Graça; Malagón, María M.; Frühbeck, Gema

    2015-01-01

    Glycerol is an important metabolite for the control of lipid accumulation in white adipose tissue (WAT) and liver. We aimed to investigate whether exogenous administration of leptin improves features of non-alcoholic fatty liver disease (NAFLD) in leptin-deficient ob/ob mice via the regulation of AQP3 and AQP7 (glycerol channels mediating glycerol efflux in adipocytes) and AQP9 (aquaglyceroporin facilitating glycerol influx in hepatocytes). Twelve-week-old male wild type and ob/ob mice were divided in three groups as follows: control, leptin-treated (1 mg/kg/d) and pair-fed. Leptin deficiency was associated with obesity and NAFLD exhibiting an AQP3 and AQP7 increase in WAT, without changes in hepatic AQP9. Adipose Aqp3 and hepatic Aqp9 transcripts positively correlated with markers of adiposity and hepatic steatosis. Chronic leptin administration (4-weeks) was associated with improved body weight, whole-body adiposity, and hepatosteatosis of ob/ob mice and to a down-regulation of AQP3, AQP7 in WAT and an up-regulation of hepatic AQP9. Acute leptin stimulation in vitro (4-h) induced the mobilization of aquaglyceroporins towards lipid droplets (AQP3) and the plasma membrane (AQP7) in murine adipocytes. Our results show that leptin restores the coordinated regulation of fat-specific AQP7 and liver-specific AQP9, a step which might prevent lipid overaccumulation in WAT and liver in obesity. PMID:26159457

  8. Oral Administration of Apple Procyanidins Ameliorates Insulin Resistance via Suppression of Pro-Inflammatory Cytokine Expression in Liver of Diabetic ob/ob Mice.

    PubMed

    Ogura, Kasane; Ogura, Masahito; Shoji, Toshihiko; Sato, Yuichi; Tahara, Yumiko; Yamano, Gen; Sato, Hiroki; Sugizaki, Kazu; Fujita, Naotaka; Tatsuoka, Hisato; Usui, Ryota; Mukai, Eri; Fujimoto, Shimpei; Inagaki, Nobuya; Nagashima, Kazuaki

    2016-11-23

    Procyanidins, the main ingredient of apple polyphenols, are known to possess antioxidative and anti-inflammatory effects associated closely with the pathophysiology of insulin resistance and type 2 diabetes. We investigated the effects of orally administered apple procyanidins (APCs) on glucose metabolism using diabetic ob/ob mice. We found no difference in body weight or body composition between mice treated with APCs and untreated mice. A 4 week oral administration of APCs containing water [0.5% (w/v)] ameliorated glucose tolerance, insulin resistance, and hepatic gluconeogenesis in ob/ob mice. APCs also suppressed the increase in the level of the pancreatic β-cell. Insulin-stimulated Akt phosphorylation was significantly enhanced; pro-inflammatory cytokine expression levels were significantly decreased, and c-Jun N-terminal kinase phosphorylation was downregulated in the liver of those mice treated with APCs. In conclusion, APCs ameliorate insulin resistance by improving hepatic insulin signaling through suppression of hepatic inflammation in ob/ob mice, which may be a mechanism with possible beneficial health effects of APCs in disturbed glucose metabolism.

  9. SmedOB1 is Required for Planarian Homeostasis and Regeneration

    PubMed Central

    Yin, Shanshan; Huang, Yan; Zhangfang, Yingnan; Zhong, Xiaoqin; Li, Pengqing; Huang, Junjiu; Liu, Dan; Songyang, Zhou

    2016-01-01

    The planarian flatworm is an emerging model that is useful for studying homeostasis and regeneration due to its unique adult stem cells (ASCs). Previously, planaria were found to share mammalian TTAGGG chromosome ends and telomerases; however, their telomere protection proteins have not yet been identified. In Schmidtea mediterranea, we identified a homologue of the human protection of telomeres 1 (POT1) with an OB-fold (SmedOB1). SmedOB1 is evolutionarily conserved among species and is ubiquitously expressed throughout the whole body. Feeding with SmedOB1 double-stranded RNAs (dsRNAs) led to homeostasis abnormalities in the head and pharynx. Furthermore, several ASC progeny markers were downregulated, and regeneration was impaired. Here we found that SmedOB1 is required for telomeric DNA-protein complex formation and it associates with the telomere TTAGGG sequence in vitro. Moreover, DNA damage and apoptosis signals in planarian were significantly affected by SmedOB1 RNAi. We also confirmed these phenotypes in Dugesia japonica, another flatworm species. Our work identified a novel telomere-associated protein SmedOB1 in planarian, which is required for planarian homeostasis and regeneration. The phylogenetic and functional conservations of SmedOB1 provide one mechanism by which planarians maintain telomere and genome stability to ensure their immortality and shed light on the regeneration medicine of humans. PMID:27654173

  10. Analysis of the kinematic structure in the Cygnus OB1 association

    NASA Astrophysics Data System (ADS)

    Costado, M. T.; Alfaro, E. J.; González, M.; Sampedro, L.

    2017-03-01

    The Cygnus OB1 association is part of a larger star-forming complex located in the direction of Cygnus, but whose main sub-systems may be distributed at different distances from the sun. We have collected radial velocity (RV) data for more than 300 stars in an area of 5 x 5 squared degrees centered in the Cygnus OB1 association from the literature. This area also covers part of the Cygnus OB3 and OB9 associations, because of the diffuse limits between them. In this poster, we present the results of a clustering analysis in the subspace of the phase space formed by angular coordinates and RV in the field of the Cygnus OB1 association using the current available data. Three main groups have been detected corresponding to different RV and distances.

  11. The Puppis region and the last crusade for faint OB stars

    NASA Astrophysics Data System (ADS)

    Orsatti, Ana M.

    1992-08-01

    UBV photoelectric and photographic measurements of OB stars from a list of 397 OB stars and 5 early-type supergiants and from the Luminous Stars Survey are presented. The galactic distribution of the OB stars in the region shows concentrations around the open clusters Ruprecht 44 and Ruprecht 55, and the presence of an important grouping of young stars located far below the plane. The distribution in latitude shows that young stars in the region are not restricted to a thin sheet around the plane but are spread over negative latitudes reaching at least b = -5 deg. In longitude, the OB distribution exhibits a concentration of Ob stars in the interval 244-251 deg; this is argued to be due to the presence of the local arm extension.

  12. Selective activation of FGFR4 by an FGF19 variant does not improve glucose metabolism in ob/ob mice.

    PubMed

    Wu, Xinle; Ge, Hongfei; Lemon, Bryan; Weiszmann, Jennifer; Gupte, Jamila; Hawkins, Nessa; Li, Xiaofan; Tang, Jie; Lindberg, Richard; Li, Yang

    2009-08-25

    FGF19 is a hormone that regulates bile acid and glucose homeostasis. Progress has been made in identifying cofactors for receptor activation. However, several functions of FGF19 have not yet been fully defined, including the actions of FGF19 on target tissues, its FGF receptor specificity, and the contributions of other cofactors, such as heparin. Here, we explore the requirements for FGF19-FGFR/co-receptor interactions and signaling in detail. We show that betaKlotho was essential for FGF19 interaction with FGFRs 1c, 2c, and 3c, but FGF19 was able to interact directly with FGFR4 in the absence of betaKlotho in a heparin-dependent manner. Further, FGF19 activated FGFR4 signaling in the presence or absence of betaKlotho, but activation of FGFRs 1c, 2c, or 3c was completely betaKlotho dependent. We then generated an FGF19 molecule, FGF19dCTD, which has a deletion of the C-terminal region responsible for betaKlotho interaction. We determined that betaKlotho-dependent FGFR1c, 2c, and 3c interactions and activation were abolished, and betaKlotho-independent FGFR4 activation was preserved; therefore, FGF19dCTD is an FGFR4-specific activator. This unique FGF19 molecule specifically activated FGFR4-dependent signaling in liver and suppressed CYP7A1 expression in vivo, but was unable to activate signaling in adipose where FGFR4 expression is very low. Interestingly, unlike FGF19, treatment of ob/ob mice with FGF19dCTD failed to improve glucose levels and insulin sensitivity. These results suggest that FGF19-regulated liver bile acid metabolism could be independent of its glucose-lowering effect, and direct FGFR activation in adipose tissue may play an important role in the regulation of glucose homeostasis.

  13. The CIDA Variability Survey of Orion OB1. I. The Low-Mass Population of Ori OB1a and 1b

    NASA Astrophysics Data System (ADS)

    Briceño, Cesar; Calvet, Nuria; Hernández, J.; Vivas, A. K.; Hartmann, Lee; Downes, J. J.; Berlind, Perry

    2005-02-01

    We present results of a large-scale, multiepoch optical survey of the Orion OB1 association, carried out with the QUEST camera at the Venezuela National Astronomical Observatory. We identify for the first time the widely spread low-mass, young population in the Ori OB1a and OB1b subassociations. Candidate members were picked up by their variability in the V band and position in color-magnitude diagrams. We obtained spectra to confirm membership. In a region spanning ~68 deg2, we found 197 new young stars; of these, 56 are located in the Ori OB1a subassociation and 141 in Ori OB1b. The spatial distribution of the low-mass young stars is spatially coincident with that of the high-mass members but suggests a much sharper edge to the association. Comparison with the spatial extent of molecular gas and extinction maps indicates that the subassociation Ori OB1b is concentrated within a ringlike structure of radius ~2°(~15 pc at 440 pc), centered roughly on the star ɛ Ori in the Orion belt. The ring is apparent in 13CO and corresponds to a region with an extinction AV>=1. The stars exhibiting strong Hα emission, an indicator of active accretion, are found along this ring, whereas the center is populated with weak Hα-emitting stars. In contrast, Ori OB1a is located in a region devoid of gas and dust. We identify a grouping of stars within a ~3 deg2 area located in Ori OB1a, roughly clustered around the B2 star 25 Ori. The Herbig Ae/Be star V346 Ori is also associated with this grouping, which could be an older analog of σ Ori. Using several sets of evolutionary tracks, we find an age of 7-10 Myr for Ori OB1a and of ~4-6 Myr for Ori OB1b, consistent with previous estimates from OB stars. Indicators such as the equivalent width of Hα and near-IR excesses show that the number of accreting low-mass stars decreases sharply between Ori OB1b and Ori OB1a. These results indicate that although a substantial fraction of accreting disks remain at ages ~5 Myr, inner disks are

  14. Design, synthesis, and application of OB2C combinatorial peptide and peptidomimetic libraries.

    PubMed

    Liu, Ruiwu; Shih, Tsung-Chieh; Deng, Xiaojun; Anwar, Lara; Ahadi, Sara; Kumaresan, Pappanaicken; Lam, Kit S

    2015-01-01

    The "one-bead two-compound" (OB2C) combinatorial library is constructed on topologically segregated trifunctional bilayer beads such that each bead has a fixed cell-capturing ligand and a random library compound co-displayed on its surface and a chemical coding tag (bar code) inside the bead. An OB2C library containing thousands to millions of compounds can be synthesized and screened concurrently within a short period of time. When live cells are incubated with such OB2C libraries, every bead will be coated with a monolayer of cells. The cell membranes of the captured cells facing the bead surface are exposed to the library compounds tethered to each bead. A specific biochemical or cellular response can be detected with an appropriate reporter system. The OB2C method enables investigators to rapidly discover synthetic molecules that not only interact with cell-surface receptors but can also stimulate or inhibit downstream cell signaling. To demonstrate this powerful method, one OB2C peptide library and two OB2C peptidomimetic libraries were synthesized and screened against Molt-4 lymphoma cells to discover "death ligands." Apoptosis of the bead-bound cells was detected with immunocytochemistry using horseradish peroxidase (HRP)-conjugated anti-cleaved caspase-3 antibody and 3,3'-diaminobenzidine as a substrate. Two novel synthetic "death ligands" against Molt-4 cells were discovered using this OB2C library approach.

  15. D Recording of a 19-CENTURY OB River Ship

    NASA Astrophysics Data System (ADS)

    Pushkarev, A. A.; Zaytceva, O. V.; Vavulin, M. V.; Skorobogatova, A. Y.

    2016-06-01

    A 3D recording of a 19-century wooden ship discovered on the bank of the river Ob (Western Siberia) was performed in autumn 2015. The archaeologized ship was partly under water, partly lying ashore, buried under fluvial deposits. The 3D recording was performed in October, when the water level was at its lowest after clearing the area around the ship. A 3D recording at the place of discovery was required as part of the ship museumification and reconstruction project. The works performed were primarily aimed at preserving as much information about the object as possible. Given the location and peculiar features of the object, a combination of close-range photogrammetry and aerial photography was considered to be the best possible solution for creating a high-quality 3D model. The dismantled ship was delivered to Nizhnevartovsk Museum of Local History in October 2015. The ship is going to be reassembled using the created 3D model to be exhibited in the museum. The resulting models are also going to be used to make a virtual 3D reconstruction of the ship in the future. We shot a stereoscopic video for Nizhnevartovsk Museum of Local History to let visitors see the place of discovery and explore the ship in greater details. Besides, 3D printing allowed for creating a miniature of the ship, which is also going to be included in the exposition devoted to this unique discovery.

  16. A Photometric Survey of Ori OB1b

    NASA Astrophysics Data System (ADS)

    Merritt, Allison T.; Sherry, W.

    2011-01-01

    Several mechanisms have been suggested to describe the formation of sub-stellar mass objects (SSMOs), specifically brown dwarfs. Each proposed mechanism predicts a unique spatial distribution of the brown dwarfs relative to the O and B stars of the association. We have 9 square degrees of optical (VRI) data and 7 square degrees of NIR (JHK) data of Orion OB1b. The purpose of the survey is to obtain the photometric data that will allow us to determine the spatial distribution of brown dwarfs in this region and constrain the various formation theories. We present an overview of the survey, with an emphasis on the NIR data, as well as color-magnitude diagrams. This research was supported by the NOAO/KPNO Research Experiences for Undergraduates (REU) Program which is funded by the National Science Foundation Research Experiences for Undergraduates Program and the Department of Defense ASSURE program through Scientific Program Order No. 13 (AST-0754223) of the Cooperative Agreement No. AST-0132798 between the Association of Universities for Research in Astronomy (AURA) and the NSF.

  17. COSMIC ORIGINS SPECTROGRAPH OBSERVATIONS OF TRANSLUCENT CLOUDS: Cyg OB2 8A

    SciTech Connect

    Snow, Theodore P.; Destree, Joshua D.; Burgh, Eric B.; Ferguson, Ryan M.; Danforth, Charles W.; Cordiner, Martin E-mail: destree@colorado.ed E-mail: ryan.m.ferguson@colorado.ed E-mail: martin.cordiner@nasa.go

    2010-09-10

    Data from the Cosmic Origins Spectrograph (COS) are presented for the first highly reddened target (Cyg OB2 8A) under the COS Science Team's guaranteed time allocation. Column densities of ionic, atomic, and molecular species are reported and implications are discussed. Data from Cyg OB2 8A demonstrate the ability to analyze highly reddened interstellar sight lines with the COS that were unavailable to previous UV instruments. Measured column densities indicate that the Cyg OB2 8A line of sight contains multiple diffuse clouds rather than a dominant translucent cloud.

  18. Attenuated pain response of obese mice (B6.Cg-lep(ob)) is affected by aging and leptin but not sex.

    PubMed

    Rodgers, Helen M; Liban, Suadi; Wilson, Linda M

    2014-01-17

    Genetically obese mice (B6.Cg-lep(ob)) manifest decreased responses to noxious thermal stimuli (hotplate test) suggesting endogenous analgesia (Roy et al., 1981). To examine further the analgesic response of these mice, we conducted 4 experiments. Experiment 1 assessed the response of ob/ob mice to tail flick, another noxious thermal test. Tail-flick testing was performed on B6.Cg-lep(ob) mice (n=14) and B6.Cg-lep(OB/?) (n=12) across a range of temperatures. Ob/ob mice exhibited longer latencies than control mice at all temperatures tested. In Experiment 2, potential sex differences were examined. Tail-flick latencies in male and female ob/ob mice (n=6/group) did not differ. The final 2 experiments examined factors that could modulate endogenous analgesia. Experiment 3 assessed the effects of aging in ob/ob mice (n=10/group). Older mice displayed longer tail-flick latencies than did younger mice. Experiment 4 examined the effect of leptin administration in the leptin-deficient ob/ob mice. Two groups (n=10/group) of ob/ob mice received osmotic pump implants filled with either leptin or vehicle, and were tail-flick tested at days 7 and 14 post-implantation. Ob/ob mice receiving leptin showed shorter latencies than did vehicle-receiving ob/ob mice. Taken together, these results support earlier reports of heightened analgesia in ob/ob mice and suggest that aging further reduces the already impaired pain response. Furthermore, leptin deficiency partially contributes to decreased pain sensation of ob/ob mice.

  19. Yhhu981, a novel compound, stimulates fatty acid oxidation via the activation of AMPK and ameliorates lipid metabolism disorder in ob/ob mice

    PubMed Central

    Zeng, Hong-liang; Huang, Su-ling; Xie, Fu-chun; Zeng, Li-min; Hu, You-hong; Leng, Ying

    2015-01-01

    Aim: Defects in fatty acid metabolism contribute to the pathogenesis of insulin resistance and obesity. In this study, we investigated the effects of a novel compound yhhu981 on fatty acid metabolism in vitro and in vivo. Methods: The capacity to stimulate fatty acid oxidation was assessed in C2C12 myotubes. The fatty acid synthesis was studied in HepG2 cells using isotope tracing. The phosphorylation of AMPK and acetyl-CoA carboxylase (ACC) was examined with Western blot analysis. For in vivo experiments, ob/ob mice were orally treated with yhhu981 acutely (300 mg/kg) or chronically (150 or 300 mg·kg−1·d−1 for 22 d). On the last day of treatment, serum and tissue samples were collected for analysis. Results: Yhhu981 (12.5–25 μmol/L) significantly increased fatty acid oxidation and the expression of related genes (Sirt1, Pgc1α and Mcad) in C2C12 myotubes, and inhibited fatty acid synthesis in HepG2 cells. Furthermore, yhhu981 dose-dependently increased the phosphorylation of AMPK and ACC in both C2C12 myotubes and HepG2 cells. Compound C, an AMPK inhibitor, blocked fatty acid oxidation in yhhu981-treated C2C12 myotubes and fatty acid synthesis decrease in yhhu981-treated HepG2 cells. Acute administration of yhhu981 decreased the respiratory exchange ratio in ob/ob mice, whereas chronic treatment with yhhu981 ameliorated the lipid abnormalities and ectopic lipid deposition in skeletal muscle and liver of ob/ob mice. Conclusion: Yhhu981 is a potent compound that stimulates fatty acid oxidation, and exerts pleiotropic effects on lipid metabolism by activating AMPK. PMID:25732571

  20. Divergent effects of a CLA-enriched beef diet on metabolic health in ApoE-/- and ob/ob mice.

    PubMed

    Reynolds, Clare M; Toomey, Sinead; McBride, Rachael; McMonagle, Jolene; Morine, Melissa J; Belton, Orina; Moloney, Aidan P; Roche, Helen M

    2013-02-01

    Conjugated linoleic acid (CLA) is found naturally in meat and dairy products, and represents a potential therapeutic functional nutrient. However, given the discrepancies in isomer composition and concentration, controversy surrounds its proposed antidiabetic, antiobesity effects. This study focused on the effects of CLA-enriched beef (composed predominantly of c9, t11-CLA) in two separate models of metabolic disease: proatherosclerotic ApoE(-/-) mice and diabetic, leptin-deficient ob/ob mice. Animals were fed CLA-enriched beef for 28 days, and markers of the metabolic syndrome and atherosclerosis were assessed. Comprehensive hepatic transcriptomic analysis was completed to understand divergent metabolic effects of CLA. CLA-enriched beef significantly reduced plasma glucose, insulin, nonesterified fatty acid and triacylglycerol and increased adiponectin levels in ob/ob mice. In contrast, plasma lipid profiles and glucose homeostasis deteriorated and promoted atherosclerosis following the CLA-enriched beef diet in ApoE(-/-) mice. Hepatic transcriptomic profiling revealed divergent effects of CLA-enriched beef on insulin signaling and lipogenic pathways, which were adversely affected in ApoE(-/-) mice. This study demonstrated clear divergence in the effects of CLA. CLA-enriched beef improved metabolic flexibility in ob/ob mice, resulting in enhanced insulin sensitivity. However, CLA-enriched diet increased expression of lipogenic genes, resulting in inefficient fatty acid storage which increases lipotoxicity in peripheral organs, and led to profound metabolic dysfunction in ApoE(-/-) mice. While CLA may have potential health effects, in some circumstances, caution must be exercised in presenting this bioactive lipid as a potential functional food for the treatment of metabolic disease.

  1. Study of eclipsing binary and multiple systems in ob associations. II. The cygnus ob region: V443 Cyg, V456 Cyg, and V2107 Cyg

    SciTech Connect

    Bakış, V.; Bakış, H.; Hensberge, H.; Bilir, S.; Yılmaz, F.; Kıran, E.; Demircan, O.; Zejda, M.; Mikulášek, Z.

    2014-06-01

    Three presumably young eclipsing binary systems in the direction of the Cygnus OB1, OB3, and OB9 associations are studied. Component spectra are reconstructed and their orbits are determined using light curves and spectra disentangling techniques. V443 Cyg and V456 Cyg have circular orbits while the light curve of V2107 Cyg imposes a slightly eccentric orbit (e = 0.045 ± 0.03). V443 Cyg harbors F-type stars, not young early-A stars as previously suggested in the literature based solely on photometry. It appears to be situated in the foreground (distance 0.6 ± 0.2 kpc) of the young stellar populations in Cygnus. V456 Cyg, at a distance of 0.50 ± 0.03 kpc, consists of a slightly metal-weak A-type star and an early-F star. The age of both systems, on or very near to the main sequence, remains uncertain by an order of magnitude. V2107 Cyg is a more massive system (8.9 ± 2 and 4.5 ± 1.2 M {sub ☉}) at 1.5 ± 0.5 kpc and, also kinematically, a strong candidate-member of Cyg OB1. The more massive component is slightly evolved and appears to undergo non-radial βCep-type pulsations. The Doppler signal of the secondary is barely detectable. A more extensive, asteroseismological study is necessary to fix masses more precisely. Nevertheless, the position of the primary in the H-R diagram confines the age reasonably well to 20 ± 5 Myr, indicating that for Cyg OB1 has a similar extent of star formation history as that established for Cyg OB2.

  2. Post-T Tauri Stars in the Nearest OB Association

    NASA Astrophysics Data System (ADS)

    Mamajek, Eric E.; Meyer, Michael R.; Liebert, James

    2002-09-01

    We present results of a spectroscopic survey of X-ray- and proper-motion-selected samples of late-type stars in the Lower Centaurus-Crux (LCC) and Upper Centaurus-Lupus (UCL) subgroups of the nearest OB association: Scorpius-Centaurus. The primary goals of the survey are to determine the star formation history of the OB subgroups and to assess the frequency of accreting stars in a sample dominated by ``post-T Tauri'' pre-main-sequence (PMS) stars. We investigate two samples: (1) proper-motion candidates from the ACT Catalog and Tycho Reference Catalog (TRC) with X-ray counterparts in the ROSAT All-Sky Survey (RASS) Bright Source Catalog and (2) G- and K-type stars in the Hipparcos catalog found to be candidate members by de Zeeuw et al. We obtained optical spectra of 130 candidates with the Siding Spring 2.3 m dual-beam spectrograph. PMS stars were identified by (1) strong Li λ6707 absorption, (2) subgiant surface gravities, (3) proper motions consistent with Sco-Cen membership, and (4) H-R diagram positions consistent with being PMS. We find 93% of the RASS-ACT/TRC stars to be probable PMS members, compared with 73% of the Hipparcos candidates. We demonstrate that measuring the gravity-sensitive band ratio of Sr II λ4077 to Fe I λ4071 is a valuable means of discriminating PMS and zero-age main-sequence (ZAMS) stars. Using secular parallaxes and Hipparcos, Tycho-2, and Two Micron All Sky Survey photometry, we construct an H-R diagram. Depending on the choice of published evolutionary tracks, we find the mean ages of the PMS populations to range between 17 and 23 Myr for LCC and 15 and 22 Myr for UCL. Taking into account observational errors, it appears that 95% of the low-mass star formation in each subgroup must have occurred in less than 8 Myr (LCC) and 12 Myr (UCL). Using the Bertelli et al. tracks, we find main-sequence turnoff ages for Hipparcos B-type members to be 16+/-1 Myr for LCC and 17+/-1 Myr for UCL. Contrary to previous findings, it appears that

  3. Variability survey of brightest stars in selected OB associations

    NASA Astrophysics Data System (ADS)

    Laur, Jaan; Kolka, Indrek; Eenmäe, Tõnis; Tuvikene, Taavi; Leedjärv, Laurits

    2017-02-01

    Context. The stellar evolution theory of massive stars remains uncalibrated with high-precision photometric observational data mainly due to a small number of luminous stars that are monitored from space. Automated all-sky surveys have revealed numerous variable stars but most of the luminous stars are often overexposed. Targeted campaigns can improve the time base of photometric data for those objects. Aims: The aim of this investigation is to study the variability of luminous stars at different timescales in young open clusters and OB associations. Methods: We monitored 22 open clusters and associations from 2011 to 2013 using a 0.25-m telescope. Variable stars were detected by comparing the overall light-curve scatter with measurement uncertainties. Variability was analysed by the light curve feature extraction tool FATS. Periods of pulsating stars were determined using the discrete Fourier transform code SigSpec. We then classified the variable stars based on their pulsation periods and available spectral information. Results: We obtained light curves for more than 20 000 sources of which 354 were found to be variable. Amongst them we find 80 eclipsing binaries, 31 α Cyg, 13 β Cep, 62 Be, 16 slowly pulsating B, 7 Cepheid, 1 γ Doradus, 3 Wolf-Rayet and 63 late-type variable stars. Up to 55% of these stars are potential new discoveries as they are not present in the Variable Star Index (VSX) database. We find the cluster membership fraction for variable stars to be 13% with an upper limit of 35%. Variable star catalogue (Tables A.1-A.10) and light curves are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/598/A108

  4. DEBRIS DISKS IN THE UPPER SCORPIUS OB ASSOCIATION

    SciTech Connect

    Carpenter, John M.; Hillenbrand, Lynne A.; Mamajek, Eric E.; Meyer, Michael R.

    2009-11-10

    We present MIPS 24 mum and 70 mum photometry for 205 members of the Upper Scorpius OB Association. These data are combined with published MIPS photometry for 15 additional association members to assess the frequency of circumstellar disks around 5 Myr old stars with spectral types between B0 and M5. Twelve stars have a detectable 70 mum excess, each of which also has a detectable 24 mum excess. A total of 54 stars are identified with a 24 mum excess more than 32% above the stellar photosphere. The MIPS observations reveal 19 excess sources-8 A/F/G stars and 11 K/M stars-that were not previously identified with an 8 mum or 16 mum excess. The lack of short-wavelength emission and the weak 24 mum excess suggests that these sources are debris systems or the remnants of optically thick primordial disks with inner holes. Despite the wide range of luminosities of the stars hosting apparent debris systems, the excess characteristics are consistent with all stars having dust at similar orbital radii after factoring in variations in the radiation blowout particle size with spectral type. The results for Upper Sco are compared to similar photometric surveys from the literature to re-evaluate the evolution of debris emission. After considering the completeness limits of published surveys and the effects of stellar evolution on the debris luminosity, we find that the magnitude of the 24 mum excess around F-type stars increases between ages of 5 and 17 Myr as found by previous studies, but at approx<2.6sigma confidence. For B7-A9 and G0-K5 stars, any variations in the observed 24 mum excess emission over this age range are significant at less than 2sigma confidence.

  5. Abortion training to be required in standard Ob / Gyn curriculum.

    PubMed

    1995-02-24

    On February 15, (1995) the Accreditation Council for Graduate Medical Education announced that it will now require medical schools seeking accreditation to provide abortion training for all residents in obstetrics and gynecology. The new "Program Requirements for Residency Education in Obstetrics and Gynecology," approved unanimously, will take effect on January 1, 1996. According to the Council, the newly issued standards are the first to refer specifically to abortion. The language states, "Experience with induced abortion must be part of residency training, except for residents with moral or religious objections .... Experience with management of complications of abortion must be provided to all residents." The Council also mandates that if a medical school itself has "a religious, moral or legal" objection to teaching the procedure, it must "ensure that residents ... who do not have a religious or moral objection receive education and experience in performing abortion at another institution." Other revisions provide for expanded resident education in "primary and preventive care," due to the fact that many women rely on their obstetricians and gynecologists as their primary care physicians, as well as additional training experience in family planning, including "all reversible methods of contraception" and sterilization. In order to be certified by the American Board of Obstetrics and Gynecology, ob/gyns must graduate from an accredited residency program. In addition, teaching hospitals must be accredited to secure federal reimbursements for the medical services patients receive from residents. The Accreditation Council for Graduate Medical Education operates under the aegis of the American Medical Association, the American Board of Medical Specialties, the American Hospital Association, the Association of American Medical Colleges, and the Council of Medical Specialty Societies. Both the American Board of Obstetrics and Gynecology and the American College of

  6. Tugboat model for OB binaries, X-ray stars and pulsars.

    PubMed

    Helfand, D J; Tademaru, E

    1977-05-12

    An examination of the kinematical properties of binary OB stars, binary X-ray sources and pulsars suggests an evolutionary sequence linking an apparent low-velocity class of pulsars to the binary nature of their extreme Population I progenitors.

  7. Mass loss from very luminous OB stars and the Cygnus superbubble

    NASA Astrophysics Data System (ADS)

    Abbott, D. C.; Bieging, J. H.; Churchwell, E.

    1981-11-01

    A description is presented of radio continuum measurements of mass loss from OB stars made at a wavelength of 6 cm with the Very Large Array (VLA). Five of the six most luminous members of the stellar association Cyg OB2 were detected. The considered investigation concentrates on the most luminous stars known in the Galaxy. The stars were selected because they would exhibit the most extreme consequences of mass loss and because they tend to be the brightest radio sources. The new mass loss rates are used to predict the properties of the interstellar bubble produced by the stellar winds of Cyg OB2. The results support the interpretation of Cash et al. (1980) that X-ray emission in the direction of Cygnus indicates a superbubble whose hot interior cavity contains the Cyg OB2 association.

  8. ObsPack: a framework for the preparation, delivery, and attribution of atmospheric greenhouse gas data

    NASA Astrophysics Data System (ADS)

    Masarie, K. A.; Peters, W.; Jacobson, A. R.; Tans, P. P.

    2014-09-01

    Observation Package (ObsPack) is a framework designed to bring together atmospheric greenhouse gas observations from a variety of sampling platforms, prepare them with specific applications in mind, and package and distribute them in a self-consistent and well-documented product. Data products created using the ObsPack framework (called "ObsPack products") are intended to support carbon cycle modeling studies and represent the next generation of value-added greenhouse gas observation products modeled after the cooperative GLOBALVIEW products introduced in 1996. Depending on intended use, ObsPack products may include data in their original form reformatted using the ObsPack framework or may contain derived data consisting of averages, subsets or smoothed representations of original data. All products include extensive ancillary information (metadata) intended to help ensure the data are used appropriately, their calibration and quality assurance history are clearly described, and that individuals responsible for the measurements (data providers or principal investigators (PIs)) are properly acknowledged for their work. ObsPack products are made freely available using a distribution strategy designed to improve communication between data providers and product users. The strategy includes a data usage policy that requires users to directly communicate with data providers and an automated e-mail notification system triggered when a product is accessed. ObsPack products will be assigned a unique Digital Object Identifier (DOI) to ensure each product can be unambiguously identified in scientific literature. Here we describe the ObsPack framework and its potential role in supporting the evolving needs of both data providers and product users.

  9. Intrinsic ultraviolet (912-3200 A) energy distribution of OB stars

    NASA Technical Reports Server (NTRS)

    Longo, Renata; Stalio, Roberto; Polidan, Ronald S.; Rossi, Lucio

    1989-01-01

    Low-dispersion 500-3200-A spectra of 20 OB stars are used to derive three individual extinction curves in the wavelength range 912-1200 A. The dependence of the intrinsic UV fluxes of OB stars on both spectral type and luminosity is demonstrated. UV color indices are proposed. The results confirm the previous finding that O star spectra are not significantly bluer than the spectrum of the B0 main-sequence star Upsilon Ori.

  10. ObsPack: a framework for the preparation, delivery, and attribution of atmospheric greenhouse gas measurements

    NASA Astrophysics Data System (ADS)

    Masarie, K. A.; Peters, W.; Jacobson, A. R.; Tans, P. P.

    2014-12-01

    Observation Package (ObsPack) is a framework designed to bring together atmospheric greenhouse gas observations from a variety of sampling platforms, prepare them with specific applications in mind, and package and distribute them in a self-consistent and well-documented product. Data products created using the ObsPack framework (called "ObsPack products") are intended to support carbon cycle modeling studies and represent a next generation of value-added greenhouse gas observation products modeled after the cooperative GLOBALVIEW products introduced in 1996. Depending on intended use, ObsPack products may include data in their original form reformatted using the ObsPack framework or may contain derived data consisting of averages, subsets, or smoothed representations of original data. All products include extensive ancillary information (metadata) intended to help ensure the data are used appropriately, their calibration and quality assurance history are clearly described, and that individuals responsible for the measurements (data providers or principal investigators (PIs)) are properly acknowledged for their work. ObsPack products are made freely available using a distribution strategy designed to improve communication between data providers and product users. The strategy includes a data usage policy that requires users to directly communicate with data providers and an automated e-mail notification system triggered when a product is accessed. ObsPack products will be assigned a unique digital object identifier (DOI) to ensure each product can be unambiguously identified in scientific literature. Here we describe the ObsPack framework and its potential role in supporting the evolving needs of both data providers and product users.

  11. Novel leptin OB3 peptide-induced signaling and progression in thyroid cancers: Comparison with leptin

    PubMed Central

    Hsieh, Meng-Ti; Lai, Hsuan-Yu; Ke, Chien-Chih; Crawford, Dana R.; Lee, Oscar K.; Fu, Earl; Mousa, Shaker A.; Grasso, Patricia; Liu, Leroy F.; Chang, Heng-Yu; Tang, Heng-Yuan; Lin, Hung-Yun; Davis, Paul J.

    2016-01-01

    Obesity results in increased secretion of cytokines from adipose tissue and is a risk factor for various cancers. Leptin is largely produced by adipose tissue and cancer cells. It induces cell proliferation and may serve to induce various cancers. OB3-leptin peptide (OB3) is a new class of functional leptin peptide. However, its mitogenic effect has not been determined. In the present study, because of a close link between leptin and the hypothalamic-pituitary-thyroid axis, OB3 was compared with leptin in different thyroid cancer cells for gene expression, proliferation and invasion. Neither agent stimulated cell proliferation. Leptin stimulated cell invasion, but reduced adhesion in anaplastic thyroid cancer cells. Activated ERK1/2 and STAT3 contributed to leptin-induced invasion. In contrast, OB3 did not affect expression of genes involved in proliferation and invasion. In vivo studies in the mouse showed that leptin, but not OB3, significantly increased circulating levels of thyrotropin (TSH), a growth factor for thyroid cancer. In summary, OB3 is a derivative of leptin that importantly lacks the mitogenic effects of leptin on thyroid cancer cells. PMID:27050378

  12. A Catalog of New Spectroscopically Confirmed Massive OB Stars in Carina

    NASA Astrophysics Data System (ADS)

    Alexander, Michael J.; Hanes, Richard J.; Povich, Matthew S.; McSwain, M. Virginia

    2016-12-01

    The Carina star-forming region is one of the largest in the Galaxy, and its massive star population is still being unveiled. The large number of stars combined with high, and highly variable, interstellar extinction makes it inherently difficult to find OB stars in this type of young region. We present the results of a spectroscopic campaign to study the massive star population of the Carina Nebula, with the primary goal to confirm or reject previously identified Carina OB star candidates. A total of 141 known O- and B-type stars and 94 candidates were observed, of which 73 candidates had high enough signal-to-noise ratio to classify. We find 23 new OB stars within the Carina Nebula, a 32% confirmation rate. One of the new OB stars has blended spectra and is suspected to be a double-lined spectroscopic binary (SB2). We also reclassify the spectral types of the known OB stars and discover nine new SB2s among this population. Finally, we discuss the spatial distribution of these new OB stars relative to known structures in the Carina Nebula.

  13. Pycnogenol supplementation promotes lipolysis via activation of cAMP-dependent PKA in ob/ob mice and primary-cultured adipocytes.

    PubMed

    Ho, Jin-Nyoung; Kim, Ok-Kyung; Nam, Da-Eun; Jun, Woojin; Lee, Jeongmin

    2014-01-01

    This study investigated the PKA-dependent inhibitory effect of pycnogenol (Pyc) on lipolysis using ob/ob mice and primary mouse adipocytes. Supplementation of Pyc at 30 mg/kg significantly reduced body weight gain and visceral fat mass. The serum and hepatic triglyceride (TG) and total cholesterol (TC) levels were reduced by Pyc supplementation, and high density lipoprotein (HDL)-cholesterol level significantly increased. In addition, hormone sensitive lipase (HSL) and adipose triglyceride lipase (ATGL) mRNA levels increased with Pyc supplementation in adipose tissue of ob/ob mice. The treatment of primary cultured adipocytes with Pyc at 100 μg/mL significantly increased glycerol release, cAMP level by reduction of phosphodiestersae-3B (PDE3B), and HSL levels, but decreased protein levels of perilipin A and fatty acid synthetase (FAS). The PKA inhibitor (H89) clearly blocked the cellular levels of perilipin A and HSL, suggesting that Pyc promotes lipolysis of adipocytes through activation of cAMP-dependent PKA, resulting in induction of HSL and reduction of perilipin A. Therefore, this study may elucidate the possible mechanism of Pyc, which is a candidate for weight loss through stimulation of lipolysis.

  14. Ablation of Ghrelin O-Acyltransferase Does Not Improve Glucose Intolerance or Body Adiposity in Mice on a Leptin-Deficient ob/ob Background

    PubMed Central

    Kirchner, Henriette; Heppner, Kristy M.; Holland, Jenna; Kabra, Dhiraj; Tschöp, Matthias H.; Pfluger, Paul T.

    2013-01-01

    Type 2 Diabetes is a global health burden and based on current estimates will become an even larger problem in the future. Developing new strategies to prevent and treat diabetes is a scientific challenge of high priority. The stomach hormone ghrelin has been associated with playing a role in the regulation of glucose homeostasis. However, its precise mechanism and impact on whole glucose metabolism remains to be elucidated. This study aims to clarify the role of the two ghrelin isoforms acyl- and desacyl ghrelin in regulating glucose homeostasis. Therefore ghrelin activating enzyme Ghrelin-O-acyltransferase (GOAT) was ablated in leptin-deficient ob/ob mice to study whether specific acyl ghrelin deficiency or desacyl ghrelin abundance modifies glucose tolerance on a massively obese background. As targeted deletion of acyl ghrelin does not improve glucose homeostasis in our GOAT-ob/ob mouse model we conclude that neither acyl ghrelin nor the increased ratio of desacyl/acyl ghrelin is crucial for controlling glucose homeostasis in the here presented model of massive obesity induced by leptin deficiency. PMID:23630616

  15. Molecular Clouds and OB Association in the Sco-Cen-Lup Region

    NASA Astrophysics Data System (ADS)

    Tachihara, K.; Neuhäuser, R.; Toyoda, S.; Onishi, T.; Mizuno, A.; Fukui, Y.

    With the NANTEN radio telescope, we have surveyed more than 500 deg2 around the Scorpius-Centaurus-Lupus region in 12CO, and the molecular gas distribution has been revealed. Total mass of ~ 104 Msolar and ~ 100 of small clouds have been detected as the Lupus cloud complex. There are two subgroups of Sco OB2 association, Upper-Sco and Upper-Cen-Lup (e.g., de Geus 1989), and many star-forming scenarios controlled by the OB association are suggested (e.g., de Geus 1992). In the association, a large number of coexisting T Tauri stars (TTSs) have been found with the ROSAT All Sky Survey (Krautter et al. 1997; Wichmann et al. 1997; Preibisch et al. 1999). On the other hand, active cluster formation is taking place in ρ Oph cloud core and Lupus 3 (Tachihara et al. 1996; 2000). In order to understand the star-formation history and the effect of OB association on cloud formation and dissipation, we investigate the distribution of the TTSs, molecular clouds, and OB stars. The distribution of the OB stars and the molecular clouds show clear anti-correlation. On the other hand, considerable fractions of the TTSs distribute away from the molecular clouds (so-called ``isolated TTSs''). These suggest that molecular clouds have been dissipated quickly due to the OB stars. On the other hand, there is an expanding HI shell centered in Upper-Sco, and the Lupus cloud complex exists between the shell and the Upper-Cen-Lup. The young star clusters are located at the edge of the shell, which suggests triggered star formation. Molecular clouds and star-formation seem to be affected strongly by the present OB stars and the past supernova explosion.

  16. Detached binary system MQ Centauri and its relation with Crux OB1 Association

    NASA Astrophysics Data System (ADS)

    Tunc, Efecan; Bakış, Volkan

    2016-07-01

    In this study, the astrophysical characteristics of eclipsing binary system MQ Cen and its relation with Crux OB1 association has been investigated by means of analysing high resolution (R ˜48000) spectra and light curves in Strömgren bands. Analysis of the available data yielded high precision parameters of the system which allowed us to derive reliable age and distance. The Fourier disentangling method was applied to the composite spectra of MQ Cen for reconstructing the component spectra. The modeling of the high resolution spectra revealed that the secondary component of MQ Cen rotates slower than the synchronous rotation velocity unlike the primary star which is in synchronous rotation. The photometric distance of the binary was found to be consistent with the distance given for Crux OB1 associaton (2.7 kpc) by Kaltcheva and Georgiev (1993). Space velocity of the system also supports the membership of MQ Cen to the Crux OB1 association. Age estimation was made by comparing the positions of components on HR diagram with isochrones. Conclusion shows that MQ Cen is older than the age determined for Crux OB1 association in the literature. This result implies that MQ Cen may belong to one of the older subgroups in the Crux OB1 association complex and the stellar formation in the complex started long ago than previously predicted. The evolutionary status of the component stars suggest that both components have reached the final stage of their Main Sequence lifetime and proceed to the Giant Branch. KEYWORDS: Absolute parameters, Cru OB1, eclipsing binaries, MQ Cen, OB associations, spectral disentangling.

  17. Parameterization of DFTB3/3OB for Sulfur and Phosphorus for Chemical and Biological Applications

    PubMed Central

    2015-01-01

    We report the parametrization of the approximate density functional tight binding method, DFTB3, for sulfur and phosphorus. The parametrization is done in a framework consistent with our previous 3OB set established for O, N, C, and H, thus the resulting parameters can be used to describe a broad set of organic and biologically relevant molecules. The 3d orbitals are included in the parametrization, and the electronic parameters are chosen to minimize errors in the atomization energies. The parameters are tested using a fairly diverse set of molecules of biological relevance, focusing on the geometries, reaction energies, proton affinities, and hydrogen bonding interactions of these molecules; vibrational frequencies are also examined, although less systematically. The results of DFTB3/3OB are compared to those from DFT (B3LYP and PBE), ab initio (MP2, G3B3), and several popular semiempirical methods (PM6 and PDDG), as well as predictions of DFTB3 with the older parametrization (the MIO set). In general, DFTB3/3OB is a major improvement over the previous parametrization (DFTB3/MIO), and for the majority cases tested here, it also outperforms PM6 and PDDG, especially for structural properties, vibrational frequencies, hydrogen bonding interactions, and proton affinities. For reaction energies, DFTB3/3OB exhibits major improvement over DFTB3/MIO, due mainly to significant reduction of errors in atomization energies; compared to PM6 and PDDG, DFTB3/3OB also generally performs better, although the magnitude of improvement is more modest. Compared to high-level calculations, DFTB3/3OB is most successful at predicting geometries; larger errors are found in the energies, although the results can be greatly improved by computing single point energies at a high level with DFTB3 geometries. There are several remaining issues with the DFTB3/3OB approach, most notably its difficulty in describing phosphate hydrolysis reactions involving a change in the coordination number of

  18. Leptin promotes proliferation and metastasis of human gallbladder cancer through OB-Rb leptin receptor.

    PubMed

    Zou, Hao; Liu, Yunxia; Wei, Dong; Wang, Tao; Wang, Kun; Huang, Songquan; Liu, Lixin; Li, Yuehua; Ge, Jiayun; Li, Xiao; Zhu, Hong; Wang, Lianmin; Zhao, Songling; Zhang, Xiaowen; Wang, Lin

    2016-07-01

    Emerging evidence has shown that leptin, an adipocyte-derived cytokine that is closely associated with obesity, play a significant role in carcinogenesis and tumorigenesis. However, its impact on gallbladder cancer (GBC) remains unclear. In this study, we firstly found that leptin and its functional receptor OB-Rb were significantly co-expressed in human GBC tissues and cell lines, the content of which were higher than those in normal human gallbladder tissues. Treatment with leptin promoted the proliferation, migration and invasion of GBC cells, which were attenuated by OB-Rb shRNA. Blocking in the G2/M period of cell cycle, increasing of MMP3 and MMP9, increasing of VEGF-C/D, activation of SOCS3/JAK2/p-STAT3 pathway was demonstrated after treatment with leptin. All of these positive responses were attenuated by OB-Rb receptor shRNA. Taken together, our findings suggest that leptin promoted the proliferation, migration and invasion of GBC cells by increasing OB-Rb expression through the SOCS3/JAK2/p-STAT3 signal pathway. Targeting the leptin/OB-Rb axis could be an attractive therapeutic strategy for treatment of GBC.

  19. Efforts to Improve Immunization Coverage during Pregnancy among Ob-Gyns

    PubMed Central

    Jones, Katherine M.; Carroll, Sarah; Hawks, Debra; McElwain, Cora-Ann; Schulkin, Jay

    2016-01-01

    Background. Influenza and Tdap vaccines are vital factors for improving maternal and neonatal health outcomes. Methods. A prospective, longitudinal study was conducted to determine whether the American College of Obstetricians and Gynecologists' (ACOG's) efforts to increase ob-gyn use of their immunization toolkits and vaccination administration were successful. Pre- and postintervention questionnaires were mailed to a random sample of 1,500 ACOG members between August 2012 and July 2015. Results. Significantly more postintervention survey ob-gyns reported that they received the immunization toolkits than preintervention survey ob-gyns (84.5% versus 67.0%, p < .001). The large majority of ob-gyns from both surveys (76.9% versus 78.9%) reported that they offered or planned to offer influenza vaccinations to their patients for the 2012-2013 and 2014-2015 flu seasons. Postintervention survey respondents were significantly more likely than preintervention survey participants to report that they routinely offer Tdap vaccinations to all patients during pregnancy (76.8% versus 59.3%, p < .001). Conclusion. ACOG's efforts to improve ob-gyn use of immunization toolkits and vaccine administration appear to have been successful in several ways. ACOG's toolkits are an example of an effective intervention to overcome barriers to offering vaccines and help improve influenza and Tdap immunization coverage for pregnant women. PMID:26924918

  20. Spectroscopy of Intermediate Mass Members of the Orion OB1a and b associations

    NASA Astrophysics Data System (ADS)

    Walter, Frederick M.; Sherry, William; Kim, Serena; Brittain, Sean

    2010-08-01

    OB associations are ideal sites for probing the formation of low mass stars. There has been little systematic study of the low mass stars in the largest nearby OB association, Orion OB1, aside from the Orion Nebula and σ Ori clusters. In an attempt to map the mass function and its spatial variation from 40 to below 0.01 M_⊙, we have completed a near-IR (JHK) survey of about 18 square degrees in the Orion OB1a and OB1b associations using the CPAPIR camera on the SMARTS/CTIO 1.5m telescope, supplemented by a VRI survey using the Steward Observatory Bok/90Prime and the KPNO 4m/MOSAIC cameras, as well as deep 4m/NEWFIRM images. The photometry reveals thousands of candidate association members. We request time with HYDRA to obtain spectra of the brighter candidate members (V<19), in order to confirm youth and membership from Li abundances, chromospheric activity, and radial velocities.

  1. Experimental demonstration of OSPF-TE extensions in muiti-domain OBS networks connected by GMPLS network

    NASA Astrophysics Data System (ADS)

    Tian, Chunlei; Yin, Yawei; Wu, Jian; Lin, Jintong

    2008-11-01

    The interworking network of Generalized Multi-Protocol Label Switching (GMPLS) and Optical Burst Switching (OBS) is attractive network architecture for the future IP/DWDM network nowadays. In this paper, OSPF-TE extensions for multi-domain Optical Burst Switching networks connected by GMPLS controlled WDM network are proposed, the corresponding experimental results such as the advertising latency are also presented by using an OBS network testbed. The experimental results show that it works effectively on the OBS/GMPLS networks.

  2. The performance study of oxide by-passed(OB) lateral double diffused MOSFET

    NASA Astrophysics Data System (ADS)

    Tang, Pan-pan

    2016-10-01

    An SOI LDMOS device structure with Oxide By-passed(OB) was investigated and its breakdown mechanism and characteristic of structure was analyzed. Its performance was verified by 3D numerical simulation with SILVACO TCAD software. The simulated results show that the electrical field element of the device is modulated by the concept of similar Superjunction(SJ) structure. Compared with the SJ LDMOS device, OB LDMOS obtains the same breakdown voltage, simultaneously the specific on-resistance of the OB LDMOS reduces from 3.81mΩ·cm2 to 1.96mΩ·cm2, except for achieving comparable performance and overcoming the high aspect ratio of fabrication structure and the difficulty of accurate concentration match of SJ LDMOS.

  3. Genome Sequence of the Obligate Methanotroph Methylosinus trichosporium Strain OB3b

    SciTech Connect

    Stein, Lisa Y.; Yoon, Sukhwan; Semrau, Jeremy D.; DiSpiritto, Alan A.; Crombie, Andrew; Murrell, J.; Vuilleumier, Stephane; Kalyuzhnaya, Marina G.; Den Camp, Huub J. M. Op; Bringel, Francoise O.; Bruce, David; Cheng, Jan-Fang; Copeland, A; Goodwin, Lynne A.; Han, Cliff; Hauser, Loren John; Jetten, MSM; Lajus, Aurelie; Lapidus, Alla L.; Lucas, Susan; Medigue, Claudine; Woyke, Tanja; Zeytun, Ahmet; Klotz, Martin G

    2010-01-01

    Methylosinus trichosporium OB3b (for "oddball" strain 3b) is an obligate aerobic methane-oxidizing alphaproteobacterium that was originally isolated in 1970 by Roger Whittenbury and colleagues. This strain has since been used extensively to elucidate the structure and function of several key enzymes of methane oxidation, including both particulate and soluble methane monooxygenase (sMMO) and the extracellular copper chelator methanobactin. In particular, the catalytic properties of soluble methane monooxygenase from M. trichosporium OB3b have been well characterized in context with biodegradation of recalcitrant hydrocarbons, such as trichloroethylene. The sequence of the M. trichosporium OB3b genome is the first reported from a member of the Methylocystaceae family in the order Rhizobiales.

  4. Modeling the potential radionuclide transport by the Ob and Yenisey Rivers to the Kara Sea.

    PubMed

    Paluszkiewicz, T; Hibler, L F; Richmond, M C; Bradley, D J; Thomas, S A

    2001-01-01

    A major portion of the former Soviet Union (FSU) nuclear program is located in the West Siberian Basin. Among the many nuclear facilities are three production reactors and the spent nuclear fuel reprocessing sites, Mayak, Tomsk-7, and Krasnoyarsk-26, which together are probably responsible for the majority of the radioactive contamination found in the Ob and Yenisey River systems that feed into the Arctic Ocean through the Kara Sea. This manuscript describes ongoing research to estimate radionuclide fluxes to the Kara Sea from these river systems. Our approach is to apply a hierarchy of simple models that use existing and forthcoming data to quantify the transport and fate of radionuclide contaminants via various environmental pathways. We present an initial quantification of the contaminant inventory, hydrology, meteorology, and sedimentology of the Ob River system and preliminary conclusions from portions of the Ob River model.

  5. Gamma ray bursts versus OB associations: do they trigger star formation?

    NASA Astrophysics Data System (ADS)

    Efremov, Yu. N.; Ehlerová, S.; Palouš , J.

    1999-10-01

    We discuss differences in shapes, expansion velocities and fragmentation times of structures created by an energy deposition from a single Gamma-Ray Burst (GRB) and an OB association to the ISM. After the initial inflation, supershells produced by GRBs are almost static or slowly expanding, contrary to more rapidly expanding supershells created by OB associations. We discuss the position of the energy source relative to the symmetry plane of the galaxy: observed arc-like structures can be the most dense part of structures formed by an expansion from a source above or below the galactic plane. Arcs may also form if the expansion takes place inside a giant HI cloud. We try to reproduce the size, the age, and the average distance between OB associations in the Sextant region at the edge of LMC 4.

  6. An X-ray and Infrared Hunt for New Candidate Galactic OB Stars

    NASA Astrophysics Data System (ADS)

    Povich, Matthew S.; Alexander, Michael J.; Busk, Heather; Hanes, Richard J.; Feigelson, Eric; McSwain, M. Virginia; Townsley, Leisa K.

    2016-01-01

    Most young, massive OB stars produce X-ray emission through a variety of wind-driven shock processes, and individual massive stars are detectable out to several kpc distances in the Galactic plane using high-resolution imaging observations from the Chandra X-ray Observatory. We have developed a technique to identify known and new candidate OB stars by fitting model stellar atmospheres to the broadband infrared spectral energy distributions of X-ray-identified stars. Using this technique, we identified 94 candidate O- and early B-type stars in the Carina Nebula and an additional 98 candidates in 11 other Galactic Massive Star-Forming Regions. Visible-light and near-infrared follow-up spectroscopy of these candidates is ongoing, and initial results indicate that a majority of candidate massive stars will be spectroscopically confirmed as OB stars.

  7. Gas flow and generation of x ray emission in WR+OB binaries

    NASA Technical Reports Server (NTRS)

    Usov, V. V.

    1991-01-01

    The supersonic flow of the ionized gas in WR+OB binaries and X-ray generation are considered. X-ray emission is caused by gas heating up to temperatures of 10(exp 7) to 10(exp 8) K behind the front of shock waves. These are found in the collision of gas flowing out from the WR star with either the OB star's surface or the gas of the OB star's wind. The distribution of temperature and concentration behind the shock front are obtained. Using these distributions, the spectral power of bremsstrahlung X-ray emission of hot gas is calculated. Possible reasons that lead to a considerable difference between the observed parameters of X-ray emission of the WR binary of V 444 Cygni and the theoretically expected are discussed.

  8. Very Low Mass Objects in Orion OB1a and b

    NASA Astrophysics Data System (ADS)

    Walter, Frederick M.; Faherty, Jacqueline K.; Sherry, William H.; Brittain, Sean

    2009-02-01

    We present initial results of a search for the substellar mass population of the Orion OB1 a and b associations, based on a deep optical/near-IR survey. We are complete to about 1 magnitude fainter than the 2MASS survey at K. Global comparison of the K vs. J-K color-magnitude diagram shows an excess of objects with K>14.4 (the substellar limit in Orion OB1b) and 0.8OB1b. Near-IR spectra confirm spectral types near M7, and show the triangular H-band continuum shape associated with young (low gravity) objects. Space densities of these objects exceed a few hundred/deg2 near δ Orionis.

  9. Long-Acting PASylated Leptin Ameliorates Obesity by Promoting Satiety and Preventing Hypometabolism in Leptin-Deficient Lep(ob/ob) Mice.

    PubMed

    Bolze, Florian; Morath, Volker; Bast, Andrea; Rink, Nadine; Schlapschy, Martin; Mocek, Sabine; Skerra, Arne; Klingenspor, Martin

    2016-01-01

    Body weight loss of Lep(ob/ob) mice in response to leptin is larger than expected from the reduction in energy intake alone, suggesting a thermogenic action of unknown magnitude. We exploited the superior pharmacological properties of a novel long-acting leptin prepared via PASylation to study the contribution of its anorexigenic and thermogenic effects. PASylation, the genetic fusion of leptin with a conformationally disordered polypeptide comprising 600 Pro/Ala/Ser (PAS) residues, provides a superior way to increase the hydrodynamic volume of the fusion protein, thus retarding kidney filtration and extending plasma half-life. Here a single PAS(600)-leptin injection (300 pmol/g) resulted in a maximal weight reduction of 21% 6 days after application. The negative energy balance of 300 kJ/(4 d) was driven by a decrease in energy intake, whereas energy expenditure remained stable. Mice that were food restricted to the same extent showed an energy deficit of only 220 kJ/(4 d) owing to recurring torpor bouts. Therefore, the anorexigenic effect of PAS(600)-leptin contributes 75% to weight loss, whereas the thermogenic action accounts for 25% by preventing hypometabolism. In a second experiment, just four injections of PAS(600)-leptin (100 pmol/g) administered in 5- to 6-day intervals rectified the Lep(ob/ob) phenotype. In total, 16 nmol of PAS(600)-leptin per mouse triggered a weight loss of 43% within 20 days and normalized hypothermia and glucose homeostasis as well as hepatic steatosis. The beneficial properties of PAS(600)-leptin are substantiated by a comparison with previous studies in which approximately 400 nmol (∼25-fold) unmodified leptin was mandatory to achieve similar improvements.

  10. VizieR Online Data Catalog: OB association members in ACT+TRC Catalogs (Hoogerwerf, 2000)

    NASA Astrophysics Data System (ADS)

    Hoogerwerf, R.

    2000-05-01

    The Hipparcos Catalogue (Cat. I/239) contains members of nearby OB associations brighter than 12th magnitude in V. However, membership lists are complete only to magnitude V=7.3. In this paper we discuss whether proper motions listed in the `Astrographic Catalogue+Tycho' reference catalogue (ACT, Cat. I/246) and the Tycho Reference Catalogue (TRC, Cat. I/250), which are complete to V~10.5mag, can be used to find additional association members. Proper motions in the ACT/TRC have an average accuracy of ~3mas/yr. We search for ACT/TRC stars which have proper motions consistent with the spatial velocity of the Hipparcos members of the nearby OB associations already identified by de Zeeuw et al. (1999, Cat. J/AJ/117/354). These stars are first selected using a convergent-point method, and then subjected to further constraints on the proper-motion distribution, magnitude and colour to narrow down the final number of candidate members. Monte Carlo simulations show that the proper-motion distribution, magnitude, and colour constraints remove ~97% of the field stars, while at the same time retain more than 90% of the cluster stars. The procedure has been applied to five nearby associations: the three subgroups of Sco OB2, plus Per OB3 and Cep OB6. In all cases except Cep OB6, we find evidence for new association members fainter than the completeness limit of the Hipparcos Catalogue. However, narrow-band photometry and/or radial velocities are needed to pinpoint the cluster members, and to study their physical characteristics. (1 data file).

  11. Reconstruction of Ob River, Russia, discharge from ring widths of floodplain trees

    NASA Astrophysics Data System (ADS)

    Agafonov, Leonid I.; Meko, David M.; Panyushkina, Irina P.

    2016-12-01

    The Ob is the third largest Eurasian river supplying heat and freshwater to the Arctic Ocean. These inputs influence water salinity, ice coverage, ocean temperatures and ocean circulation, and ultimately the global climate system. Variability of Ob River flow on long time scales is poorly understood, however, because gaged flow records are short. Eleven tree-ring width chronologies of Pinus sibirica and Larix sibirica are developed from the floodplain of the Lower Ob River, analyzed for hydroclimatic signal and applied as predictors in a regression model to reconstruct 8-month average (December-July) discharge of the Ob River at Salekhard over the interval 1705-2012 (308 yrs). Correlation analysis suggests the signal for discharge comes through air temperature: high discharge and floodplain water levels favor cool growing-season air temperature, which limits tree growth for the sampled species at these high latitudes. The reconstruction model (R2 = 0.31, 1937-2009 calibration period) is strongly supported by cross-validation and analysis of residuals. Correlation of observed with reconstructed discharge improves with smoothing. The long-term reconstruction correlates significantly with a previous Ob River reconstruction from ring widths of trees outside the Ob River floodplain and extends that record by another century. Results suggest that large multi-decadal swings in discharge have occurred at irregular intervals, that variations in the 20th and 21st centuries have been within the envelope of natural variability of the past 3 centuries, and that discharge data for 1937-2009 underestimate both the variability and persistence of discharge in the last 3 centuries. The reconstruction gives ecologists, climatologists and water resource planners a long-term context for assessment of climate change impacts.

  12. Near Infrared Diffuse Interstellar Bands Toward the Cygnus OB2 Association

    NASA Astrophysics Data System (ADS)

    Hamano, Satoshi; Kobayashi, Naoto; Kondo, Sohei; Sameshima, Hiroaki; Nakanishi, Kenshi; Ikeda, Yuji; Yasui, Chikako; Mizumoto, Misaki; Matsunaga, Noriyuki; Fukue, Kei; Yamamoto, Ryo; Izumi, Natsuko; Mito, Hiroyuki; Nakaoka, Tetsuya; Kawanishi, Takafumi; Kitano, Ayaka; Otsubo, Shogo; Kinoshita, Masaomi; Kawakita, Hideyo

    2016-04-01

    We obtained the near-infrared (NIR) high-resolution (R ≡ λ/Δλ ∼ 20,000) spectra of the seven brightest early-type stars in the Cygnus OB2 association for investigating the environmental dependence of diffuse interstellar bands (DIBs). The WINERED spectrograph mounted on the Araki 1.3 m telescope in Japan was used to collect data. All 20 of the known DIBs within the wavelength coverage of WINERED (0.91 < λ < 1.36 μm) were clearly detected along all lines of sight because of their high flux density in the NIR wavelength range and the large extinction. The equivalent widths (EWs) of DIBs were not correlated with the column densities of C2 molecules, which trace the patchy dense component, suggesting that the NIR DIB carriers are distributed mainly in the diffuse component. On the basis of the correlations among the NIR DIBs both for stars in Cyg OB2 and stars observed previously, λλ10780, 10792, 11797, 12623, and 13175 are found to constitute a “family,” in which the DIBs are correlated well over the wide EW range. In contrast, the EW of λ10504 is found to remain almost constant over the stars in Cyg OB2. The extinction estimated from the average EW of λ10504 (AV ∼ 3.6 mag) roughly corresponds to the lower limit of the extinction distribution of OB stars in Cyg OB2. This suggests that λ10504 is absorbed only by the foreground clouds, implying that the carrier of λ10504 is completely destroyed in Cyg OB2, probably by the strong UV radiation field. The different behaviors of the DIBs may be caused by different properties of the DIB carriers.

  13. ObRb downregulation increases breast cancer cell sensitivity to tamoxifen.

    PubMed

    Qian, Yingying; Shi, Dongmin; Qiu, Jinrong; Zhu, Fang; Qian, Jing; He, Shaohua; Shu, Yongqian; Yin, Yongmei; Chen, Xiaofeng

    2015-09-01

    Leptin is a potent adipokine that plays an important role in the progression of breast cancer and interferes with the action of tamoxifen. We investigated the molecular mechanism underlying the effect of leptin on tamoxifen resistance in breast cancer cells that express leptin receptor (ObRb), and evaluated the impact of ObRb suppression on tamoxifen treatment in MCF-7 and tamoxifen-resistant (TAM-R) cells. Leptin-induced signaling pathway activation was examined by qRT-PCR and Western blotting. Chromatin immunoprecipitation assays were performed to further examine the binding of estrogen receptor (ER) α on the promoter of cyclin D1 (CCND1) gene. The effects of combined ObRb knockdown and tamoxifen treatment were evaluated in MCF-7 and TAM-R cells. We found that the enhanced proliferation effects induced by leptin were related to extracellular-signal-regulated kinase (ERK) 1/2 and signal transducers and activators of transcription (STAT) 3 signaling pathway activation and CCND1 upregulation. Leptin enhanced CCND1 gene transcription by inducing the binding of ERα to the promoter of CCND1 gene. ObRb knockdown significantly enhanced the inhibitory effects of tamoxifen on TAM-R cell proliferation and survival. This study suggested that long-term endocrine therapy facilitates leptin and ObRb overexpression in breast cancer cells, which attenuates the inhibitory effect of tamoxifen by activating both the ERK1/2 and STAT3 signaling pathways and upregulating CCND1 gene expression. Combination therapy involving ObRb knockdown and tamoxifen treatment may be an alternative therapeutic option for tamoxifen-resistant breast cancer.

  14. NEAR INFRARED DIFFUSE INTERSTELLAR BANDS TOWARD THE CYGNUS OB2 ASSOCIATION

    SciTech Connect

    Hamano, Satoshi; Kondo, Sohei; Sameshima, Hiroaki; Nakanishi, Kenshi; Kawakita, Hideyo; Kobayashi, Naoto; Ikeda, Yuji; Yasui, Chikako; Mizumoto, Misaki; Matsunaga, Noriyuki; Fukue, Kei; Yamamoto, Ryo; Izumi, Natsuko; Mito, Hiroyuki; Nakaoka, Tetsuya; Kawanishi, Takafumi; Kitano, Ayaka; Otsubo, Shogo; Kinoshita, Masaomi

    2016-04-10

    We obtained the near-infrared (NIR) high-resolution (R ≡ λ/Δλ ∼ 20,000) spectra of the seven brightest early-type stars in the Cygnus OB2 association for investigating the environmental dependence of diffuse interstellar bands (DIBs). The WINERED spectrograph mounted on the Araki 1.3 m telescope in Japan was used to collect data. All 20 of the known DIBs within the wavelength coverage of WINERED (0.91 < λ < 1.36 μm) were clearly detected along all lines of sight because of their high flux density in the NIR wavelength range and the large extinction. The equivalent widths (EWs) of DIBs were not correlated with the column densities of C{sub 2} molecules, which trace the patchy dense component, suggesting that the NIR DIB carriers are distributed mainly in the diffuse component. On the basis of the correlations among the NIR DIBs both for stars in Cyg OB2 and stars observed previously, λλ10780, 10792, 11797, 12623, and 13175 are found to constitute a “family,” in which the DIBs are correlated well over the wide EW range. In contrast, the EW of λ10504 is found to remain almost constant over the stars in Cyg OB2. The extinction estimated from the average EW of λ10504 (A{sub V} ∼ 3.6 mag) roughly corresponds to the lower limit of the extinction distribution of OB stars in Cyg OB2. This suggests that λ10504 is absorbed only by the foreground clouds, implying that the carrier of λ10504 is completely destroyed in Cyg OB2, probably by the strong UV radiation field. The different behaviors of the DIBs may be caused by different properties of the DIB carriers.

  15. Differentiated service in OBS networks using a dynamic FDL bank partitioning algorithm.

    PubMed

    Yonggyu, Lee; Kim, Namuk; Kim, Jaegwan; Ahn, Junseop; Kang, Minho

    2007-05-14

    In order to solve the differentiated service problem in optical burst switching (OBS) networks, we propose a dynamic fiber delay line (FDL) bank partitioning algorithm, which divides a FDL bank into several groups, using a feed-forward output buffering architecture. In the analysis, three classes and groups are considered for traffic and FDL, respectively, and each group is assigned to each class. This paper shows that the loss differentiation in OBS networks is easily accomplished in Poisson traffic environments when our dynamic algorithm is adopted.

  16. TCP traffic carrying capabilities of OBS-based hypercubes for datacenters

    NASA Astrophysics Data System (ADS)

    Argibay-Losada, Pablo Jesus; Qiao, Chunming; Peng, Limei; Tang, Wan

    2011-11-01

    High power consumption due to O/E/O processing in many conventional electronic datacenter networks can be greatly decreased by a suitable use of all-optical switching technologies. OBS is specially suited to perform this task given its bursty-data traffic friendly mode of operation. In this paper, we evaluate through analysis and simulation the performance of both OBS and electronic networks when used to carry TCP flows inside a 6D-hypercube, a highly symmetrical topology representative of datacenter networks.

  17. OBS development for long term observation in the Marmara Sea, NW Turkey

    NASA Astrophysics Data System (ADS)

    Takahashi, Narumi; Shimizu, Satoshi; Maekawa, Takuya; Kalafat, Dogan; Pinar, Ali; Citak, Seckin; Kaneda, Yoshiyuki

    2015-04-01

    We have carried out a collaboration study between Japan and Turkey since 2013, which is one of SATREPS projects, "Earthquake and Tsunami Disaster Mitigation in The Marmara Region and Disaster Education in Turkey". The main objective of this project is to reduce risk brought by earthquakes and tsunamis. In particular, the North Anatolian Fault system runs through the Marmara sea and it is expected that the seismic gap exists there according to past seismic studies. The details of seismicity distribution in the Marmara Sea is, however, still insufficient to construct fault model along the active faults. Therefore, we prepare ten ocean bottom seismographs (OBSs) to realize long term observation. We aim to identify size and depth of seismogenic zones using micro seismicity. In addition, we need to cover relative broad area from off-shore Istanbul city to the western end of the Marmara Sea. To clear these conditions, OBS specifications we need are high dynamic range and low instrument noise to observe micro seismicity, low electrical consumption to realize long term observation of over one year, high cost performance to cover the broad area for OBS installation, low cost implementation, and good operability to treat by relatively small number of persons. All items, which are three components velocity sensor, batteries, a recorder, a GPS receiver, a transponder and its transducer to control OBS retrieval, a flasher and a beacon, are installed in the 17 inches glass sphere. The natural frequency of the velocity sensor is 4.5 Hz and the frequency range of our OBS is from 4.5 Hz to 250 Hz. Data sampling is selectable among 100 Hz, 250 Hz and 500 Hz. Because our OBS is deployed by free fall, accuracy of the OBS clock is essentially one of important factors, and it is less than 0.1 ppm. And the resolution of A/D conversion performed on the recorder is 24 bit and we keep the dynamic range of over 135 dB. These data is stored on a semiconductor memory and the capacity is over

  18. Analyzing the Effects of Nitrogen Deficiency on the PHB Production of Methylosinus trichosporium OB3b

    NASA Astrophysics Data System (ADS)

    Kyauk, E.

    2011-12-01

    Polyhydroxybutyrate (PHB) is a biodegradable thermoplastic that is produced by various microorganisms. Because of its potential to replace conventional plastics, it has been closely researched in the past few years. Methanotrophic bacteria, bacteria that consume methane, produce this bioplastic when it lacks certain nutrients. The utilization of methane to produce PHB shows much promise as methane is a cheap, plentiful gas. In this study, we observed the methanotroph, Methylosinus trichosporium OB3b , and its yield of PHB in the absence of nitrogen. The optical density of Methylosinus trichosporium OB3b was measured in order to observe cell growth and PHB production patterns over a 48 hour period.

  19. Advective transport observations with MODPATH-OBS--documentation of the MODPATH observation process

    USGS Publications Warehouse

    Hanson, R.T.; Kauffman, L.K.; Hill, M.C.; Dickinson, J.E.; Mehl, S.W.

    2013-01-01

    The MODPATH-OBS computer program described in this report is designed to calculate simulated equivalents for observations related to advective groundwater transport that can be represented in a quantitative way by using simulated particle-tracking data. The simulated equivalents supported by MODPATH-OBS are (1) distance from a source location at a defined time, or proximity to an observed location; (2) time of travel from an initial location to defined locations, areas, or volumes of the simulated system; (3) concentrations used to simulate groundwater age; and (4) percentages of water derived from contributing source areas. Although particle tracking only simulates the advective component of conservative transport, effects of non-conservative processes such as retardation can be approximated through manipulation of the effective-porosity value used to calculate velocity based on the properties of selected conservative tracers. This program can also account for simple decay or production, but it cannot account for diffusion. Dispersion can be represented through direct simulation of subsurface heterogeneity and the use of many particles. MODPATH-OBS acts as a postprocessor to MODPATH, so that the sequence of model runs generally required is MODFLOW, MODPATH, and MODPATH-OBS. The version of MODFLOW and MODPATH that support the version of MODPATH-OBS presented in this report are MODFLOW-2005 or MODFLOW-LGR, and MODPATH-LGR. MODFLOW-LGR is derived from MODFLOW-2005, MODPATH 5, and MODPATH 6 and supports local grid refinement. MODPATH-LGR is derived from MODPATH 5. It supports the forward and backward tracking of particles through locally refined grids and provides the output needed for MODPATH_OBS. For a single grid and no observations, MODPATH-LGR results are equivalent to MODPATH 5. MODPATH-LGR and MODPATH-OBS simulations can use nearly all of the capabilities of MODFLOW-2005 and MODFLOW-LGR; for example, simulations may be steady-state, transient, or a combination

  20. Chronic treatment with exendin(9-39)amide indicates a minor role for endogenous glucagon-like peptide-1 in metabolic abnormalities of obesity-related diabetes in ob/ob mice.

    PubMed

    Green, B D; Irwin, N; Gault, V A; Bailey, C J; O'Harte, F P M; Flatt, P R

    2005-05-01

    Glucagon-like peptide-1 (GLP-1) is a potent insulinotropic hormone proposed to play a role in both the pathophysiology and treatment of type 2 diabetes. This study has employed the GLP-1 receptor antagonist, exendin-4(9-39)amide (Ex(9-39)) to evaluate the role of endogenous GLP-1 in genetic obesity-related diabetes and related metabolic abnormalities using ob/ob and normal mice. Acute in vivo antagonistic potency of Ex(9-39) was confirmed in ob/ob mice by blockade of the insulin-releasing and anti-hyperglycaemic actions of intraperitoneal GLP-1. In longer term studies, ob/ob mice were given once daily injections of Ex(9-39) or vehicle for 11 days. Feeding activity, body weight, and both basal and glucose-stimulated insulin secretion were not significantly affected by chronic Ex(9-39) treatment. However, significantly elevated basal glucose concentrations and impaired glucose tolerance were evident at 11 days. These disturbances in glucose homeostasis were independent of changes of insulin sensitivity and reversed by discontinuation of the Ex(9-39) for 9 days. Similar treatment of normal mice did not affect any of the parameters measured. These findings illustrate the physiological extrapancreatic glucose-lowering actions of GLP-1 in ob/ob mice and suggest that the endogenous hormone plays a minor role in the metabolic abnormalities associated with obesity-related diabetes.

  1. QoS Provisioning for TT-TR Based OBS Ring Networks

    NASA Astrophysics Data System (ADS)

    Peng, Limei; Kim, Young-Chon; Tang, Wan; Youn, Chan-Hyun

    2011-06-01

    Optical burst switching (OBS) is one of the most promising switching technologies. This paper studies the efficient OBS ring network using the TT-TR based node architecture. The TT-TR based OBS ring network can use the network resources very efficiently, but the network performance is restricted due to the limited network resources. Moreover, different network demands have different network resource requirements. It is very important to satisfy their different requirements while using the limited network resources efficiently. In this paper, Quality of Service (QoS) provisioning mechanisms are studied to solve the above mentioned problems. Two kinds of network services, namely the real-time traffic and the best-effort traffic, are considered in this paper. The real-time service is delay-sensitive that should be transmitted in a real-time manner and cannot tolerate high transmission delay; while the best-effort traffic has no strict limitation in transmission delay or loss, but the best effort are made to improve their transmission reliability. According to their different servicing requirements, different QoS provisioning mechanisms are proposed to serve them in the OBS unidirectional and bidirectional ring networks, respectively. The proposed mechanisms are evaluated and analyzed through simulation. The simulation results show that even though the proposed mechanisms cannot get absolute zero-delay or zero-loss for real-time traffic or best-effort traffic, their different requirements for delay or loss are satisfied to some significant degree.

  2. Degradation of trichloroethylene by methanol-growth cultures of Methylosinus trichosporium OB3b PP358

    SciTech Connect

    Fitch, M.W.; Georgiou, G.; Speitel, G.E. Jr.

    1996-03-01

    Methylosinus trichosporium OB3b is a methanotrophic bacteria which rapidly degrades chlorinated solvents including trichloroethylene. This report focuses on continuous growth of Methylosinus trichosporium PP358 and the influence of growth conditions on TCE degradation and transformation capacity. 20 refs., 2 tabs.

  3. BOREAS TF-9 SSA-OBS Tower Flux, Meteorological, and Soil Temperature Data

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Huemmrich, Karl (Editor); Massheder, Jonathan M.; Moncrieff, John B.; Rayment, Mark B.; Jarvis, Paul G.

    2000-01-01

    The BOREAS TF-9 team collected energy, carbon dioxide, and water vapor flux data at the BOREAS SSA-OBS site during the growing season of 1994 and most of the year for 1996. From the winter of 1995 to 1996, soil temperature data were also collected and provided. The data are available in tabular ASCII files.

  4. Uptake and effect of rare earth elements on gene expression in Methylosinus trichosporium OB3b

    DOE PAGES

    Gu, Wenyu; Farhan Ul Haque, Muhammad; DiSpirito, Alan A.; ...

    2016-05-12

    It is well-known that M. trichosporium OB3b has two forms of methane monooxygenase responsible for the initial conversion of methane to methanol, a cytoplasmic (soluble) methane monooxygenase (sMMO) and a membrane-associated (particulate) methane monooxygenase (pMMO) and that copper strongly regulates expression of these alternative forms of MMO. More recently, it has been discovered that M. trichosporium OB3b has multiple types of the methanol dehydrogenase (MeDH), i.e. the Mxa-MeDH and Xox-MeDH, and the expression of these two forms is regulated by the availability of the rare earth element, cerium. Here we extend these studies and show that lanthanum, praseodymium, neodymium andmore » samarium also regulate expression of alternative forms of MeDH. The effect of these rare earth elements on MeDH expression, however, was only observed in the absence of copper. Further, a mutant of M. trichosporium OB3b where the Mxa-MeDH was knocked out was able to grow in the presence of lanthanum, praseodymium and neodymium, but was not able to grow in the presence of samarium. In conclusion, collectively these data suggest that multiple levels of gene regulation by metals exist in M. trichosporium OB3b but that copper overrides the effect of other metals by an as yet unknown mechanism.« less

  5. Complete Genome Sequence of the Cellulolytic Thermophile Caldicellulosiruptor obsidiansis OB47T

    SciTech Connect

    Elkins, James G; Lochner, Adriane; Hamilton-Brehm, Scott; Walston Davenport, Karen; Podar, Mircea; Brown, Steven D; Land, Miriam L; Hauser, Loren John; Klingeman, Dawn Marie; Raman, Babu; Goodwin, Lynne A.; Tapia, Roxanne; Meincke, Linda; Detter, J C; Bruce, David; Han, Cliff; Palumbo, Anthony Vito; Cottingham, Robert W; Keller, Martin; Graham, David E

    2010-01-01

    Caldicellulosiruptor obsidiansis OB47T (ATCC BAA-2073; JCM 16842) is an extremely thermophilic, anaerobic bacterium capable of hydrolyzing plant-derived polymers through the expression of multidomain/multifunctional hydrolases. The complete genome sequence reveals a diverse set of carbohydrate-active enzymes and provides further insight into lignocellulosic biomass hydrolysis at high temperatures.

  6. PREDICTING GAIA’S PARALLAX DISTANCE TO THE CYGNUS OB2 ASSOCIATION WITH ECLIPSING BINARIES

    SciTech Connect

    Kiminki, Daniel C.; Kobulnicky, Henry A.; Álvarez, Carlos A. Vargas; Alexander, Michael J.; Lundquist, Michael J.

    2015-10-01

    The Cygnus OB2 Association is one of the nearest and largest collections of massive stars in the Galaxy. Situated at the heart of the “Cygnus X” complex of star-forming regions and molecular clouds, its distance has proven elusive owing to the ambiguous nature of kinematic distances along this ℓ ≃ 80° sightline and the heavy, patchy extinction. In an effort to refine the three-dimensional geometry of key Cygnus X constituents, we have measured distances to four eclipsing double-lined OB-type spectroscopic binaries that are probable members of Cyg OB2. We find distances of 1.33 ± 0.17, 1.32 ± 0.07, 1.44 ± 0.18, and 1.32 ± 0.13 kpc toward MT91 372, MT91 696, CPR2002 A36, and Schulte 3, respectively. We adopt a weighted average distance of 1.33 ± 0.06 kpc. This agrees well with spectrophotometric estimates for the Association as a whole and with parallax measurements of protostellar masers in the surrounding interstellar clouds, thereby linking the ongoing star formation in these clouds with Cyg OB2. We also identify Schulte 3C (O9.5V), a 4″ visual companion to the 4.75 day binary Schulte 3(A+B), as a previously unrecognized Association member.

  7. BOREAS TF-7 SSA-OBS Tower Flux and Meteorological Data

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Huemmrich, Karl (Editor); Pattey, Elizabeth; Desjardins, Raymond L.

    2000-01-01

    The BOREAS TF-7 team collected meteorological data as well as energy, carbon dioxide, water vapor, methane, and nitrous oxide flux data at the BOREAS SSA-OBS site. The data were collected from 24-May to 19-Sep-1994. The data are available in tabular ASCII files.

  8. X-Ray Emission from Massive Stars in Cyg OB2

    NASA Astrophysics Data System (ADS)

    Rauw, G.; Nazé, Y.; Wright, N. J.; Drake, J. J.; Guarcello, M. G.; Prinja, R. K.; Peck, L. W.; Albacete Colombo, J. F.; Herrero, A.; Kobulnicky, H. A.; Sciortino, S.; Vink, J. S.

    2015-11-01

    We report on the analysis of the Chandra-ACIS data of O, B, and WR stars in the young association Cyg OB2. X-ray spectra of 49 O-stars, 54 B-stars, and 3 WR-stars are analyzed and for the brighter sources, the epoch dependence of the X-ray fluxes is investigated. The O-stars in Cyg OB2 follow a well-defined scaling relation between their X-ray and bolometric luminosities: {log}\\\\frac{{L}{{X}}}{{L}{bol}}=-7.2+/- 0.2. This relation is in excellent agreement with the one previously derived for the Carina OB1 association. Except for the brightest O-star binaries, there is no general X-ray overluminosity due to colliding winds in O-star binaries. Roughly half of the known B-stars in the surveyed field are detected, but they fail to display a clear relationship between LX and Lbol. Out of the three WR stars in Cyg OB2, probably only WR 144 is itself responsible for the observed level of X-ray emission, at a very low {log}\\\\frac{{L}{{X}}}{{L}{bol}}=-8.8+/- 0.2. The X-ray emission of the other two WR-stars (WR 145 and 146) is most probably due to their O-type companion along with a moderate contribution from a wind-wind interaction zone.

  9. BOREAS TF-3 NSA-OBS Tower Flux, Meteorological, and Soil Temperature Data

    NASA Technical Reports Server (NTRS)

    Wofsy, Steven; Sutton, Doug; Goulden, Mike; Hall, Forrest G. (Editor); Huemmrich, Karl (Editor)

    2000-01-01

    The BOReal Ecosystem-Atmosphere Study Tower Flux (BOREAS TF-3) team collected tower flux, surface meteorological, and soil temperature data at the BOREAS Northern Study Area-Old Black Spruce (NSA-OBS) site continuously from the March 1994 through October 1996. The data are available in tabular ASCII files.

  10. AN R- AND I-BAND PHOTOMETRIC VARIABILITY SURVEY OF THE CYGNUS OB2 ASSOCIATION

    SciTech Connect

    Henderson, C. B.; Stanek, K. Z.; Pejcha, O.; Prieto, J. L.

    2011-06-01

    We present a catalog of photometrically variable stars discovered within two 21.'3 x 21.'3 fields centered on the Cygnus OB2 association (Cyg OB2). There have hitherto been no deep optical variability studies of Cyg OB2, despite it being replete with early-type massive stars, likely due to the high and variable extinction (up to A{sub V} {approx} 20) that permeates much of the region. Here, we provide results of the first variability study with this combination of spatial coverage ({approx}0.5 deg) and photometric depth (R {approx} 21 mag). We find 121 stars to be variable in both R and I bands, 115 of them newly discovered. Of the 121 variables, we identify 27 eclipsing binaries and eclipsing-binary candidates, 52 pulsating variables, and 20 potential Herbig Ae/Be stars. Confirming both the status and the cluster membership of the Herbig Ae/Be stars would address the uncertainty regarding the age and star formation history of Cyg OB2. We match our catalog to known variables and binaries in the region, Two Micron All Sky Survey near-IR data, and Chandra X-ray observations to find counterparts to new variables in other wavelengths.

  11. Purification and characterization of oligonucleotide binding (OB)-fold protein from medicinal plant Tinospora cordifolia.

    PubMed

    Amir, Mohd; Haque, Md Anzarul; Wahiduzzaman; Dar, Mohammad Aasif; Islam, Asimul; Ahmad, Faizan; Hassan, Md Imtaiyaz

    2016-01-01

    The oligonucleotide binding fold (OB-fold) is a small structural motif present in many proteins. It is originally named for its oligonucleotide or oligosaccharide binding properties. These proteins have been identified as essential for replication, recombination and repair of DNA. We have successfully purified a protein contains OB-fold from the stem of Tinospora cordifolia, a medicinal plants of north India. Stems were crushed and centrifuged, and fraction obtained at 60% ammonium sulphate was extensively dialyzed and applied to the weak anion exchange chromatography on Hi-Trap DEAE-FF in 50mM Tris-HCl buffer at pH 8.0. Eluted fractions were concentrated and applied to gel filtration column to get pure protein. We observed a single band of 20-kDa on SDS-PAGE. Finally, the protein was identified as OB-fold by MALDI-TOF. The purified OB-fold protein was characterized for its secondary structural elements using circular dichroism (CD) in the far-UV region. Generally the OB-fold has a characteristic feature as five-stranded beta-sheet coiled to form a closed beta- barrel. To estimate its chemical stability, guanidinium chloride-induced denaturation curve was followed by observing changes in the far-UV CD as a function of the denaturant concentration. Analysis of this denaturation curve gave values of 8.90±0.25kcalmol(-1) and 3.78±0.18M for ΔGD° (Gibbs free energy change at 25°C) and Cm (midpoint of denaturation), respectively. To determine heat stability parameters of OB-fold protein, differential scanning calorimetry was performed. Calorimetric values of ΔGD°, Tm (midpoint of denaturation), ΔHm (enthalpy change at Tm), and ΔCp (constant-pressure heat capacity change) are 9.05±0.27kcalmol(-1), 85.2±0,3°C, 105±4kcalmol(-1) and 1.6±0.08kcalmol(-1)K(-1). This is the first report on the isolation, purification and characterization of OB-fold protein from a medicinal plant T. cordifolia.

  12. The deep OB star population in Carina from the VST Photometric Hα Survey (VPHAS+)

    NASA Astrophysics Data System (ADS)

    Mohr-Smith, M.; Drew, J. E.; Napiwotzki, R.; Simón-Díaz, S.; Wright, N. J.; Barentsen, G.; Eislöffel, J.; Farnhill, H. J.; Greimel, R.; Monguió, M.; Kalari, V.; Parker, Q. A.; Vink, J. S.

    2017-02-01

    Massive OB stars are critical to the ecology of galaxies and yet our knowledge of OB stars in the Milky Way, fainter than V ∼ 12, remains patchy. Data from the VST Photometric Hα Survey (VPHAS+) permit the construction of the first deep catalogues of blue excess-selected OB stars, without neglecting the stellar field. A total of 14 900 candidates with 2MASS cross-matches are blue-selected from a 42 deg2 region in the Galactic plane, capturing the Carina Arm over the Galactic longitude range 282° ≲ ℓ ≲ 293°. Spectral energy distribution fitting is performed on these candidates' combined VPHAS+ u, g, r, i and 2MASS J, H, K magnitudes. This delivers effective temperature constraints, statistically separating O from early-B stars and high-quality extinction parameters, A0 and RV (random errors typically ∼0.1). The high-confidence O-B2 candidates number 5915 and a further 5170 fit to later B spectral type. Spectroscopy of 276 of the former confirms 97 per cent of them. The fraction of emission-line stars among all candidate B stars is 7-8 per cent. Greyer (RV > 3.5) extinction laws are ubiquitous in the region, over the distance range 2.5-3 to ∼10 kpc. Near prominent massive clusters, RV tends to rise, with particularly large and chaotic excursions to RV ∼ 5 seen in the Carina Nebula. The data reveal a hitherto unnoticed association of 108 O-B2 stars around the O5If+ star LSS 2063 (ℓ = 289.77°, b = -1.22°). Treating the OB star scaleheight as a constant within the thin disc, we find an orderly mean relation between extinction (A0) and distance in the Galactic longitude range, 287.6° < ℓ < 293.5°, and infer the subtle onset of thin-disc warping. A halo around NGC 3603, roughly a degree in diameter, of ∼500 O-B2 stars with 4 < A0(mag) < 7 is noted.

  13. The HII Regions and OB Stars of M33 and NCG 6822.

    NASA Astrophysics Data System (ADS)

    Patel, Kanan

    1995-01-01

    We have used Hα and photometric data for two morphologically distinct Local Group galaxies, the spiral M33 and dwarf irregular NGC 6822, to study the distribution of the luminous blue O and B (OB) stars and HII regions in the galaxies as well as to determine whether individual regions of the galaxies are separately and/or collectively in a state of ionization balance. In the case of M33, we have concentrated on the inner 1 kpc region of the galaxy. Using the H alpha data, three distinct ionized gas environments (bright, halo and field) defined by the surface brightness of the Hα emission have been identified. We find that ~50% of the OB stars are located in the field, so that 1/2 of the lifetime of OB stars must be spent outside recognizable HII regions. We show that a possible origin for the large field OB population is that they were born in and subsequently percolated out of the ~10 ^3 giant molecular clouds with masses _sp{~}>10 ^3Modot predicted to exist within the inner kpc of the galaxy. Using UBV photometry and stellar ionization models, we predict Hα fluxes in the bright, halo and field regions. Our findings suggest that star formation rates obtained from luminosities must underestimate the true star formation rate within the inner region of M33. In the case of NGC 6822, four distinct components of the Hα emission (bright, halo, diffuse and field) differentiated by their surface brightnesses have been identified. We find that only 1/4 of the OB stars are found in the combined bright halo regions, suggesting that OB stars spend roughly 3/4 of their lifetimes outside "classical" HII regions. Molecular cloud lifetimes after forming OB stars could be as low as ~1 -3 times 10^6 yrs or 1/4 the typical main sequence lifetimes of OB stars if stars escape from bright HII regions by destroying their parent clouds. Additionally, the field population of OB stars cannot have originated in and percolated out of existing HII regions. Comparing the observed H

  14. Photoionization of the diffuse interstellar medium and galactic halo by OB associtations

    NASA Technical Reports Server (NTRS)

    Dove, James B.; Shull, J. Michael

    1994-01-01

    Assuming smoothly varying H I distributions in te Galactic disk, we have calculated the geometry of diffuse II regions due to OB associations in the Galactic plane. Near the solar circle, OB associations with a Lyman continuum (Lyc) photon luminosity Psi(sub Lyc) = 3.3 x 10(exp 7) cm(exp -2) s(exp -1), produce H II regions that are density bounded in the vertical direction (H II chimneys) allowing Lyc to escape the gaseous disk and penetrate into the Galactic halo. We provide analytic formulae for the Lyc escape fraction as functions of S(sub 0) O-star catalog of Garmany and a new Lyc stellar stellar Lyc stellar flux calibration, we find a production rate of Lyc photons by OB associations within 2.5 kpc of Psi(sub Lyc) = 3.3 x 10(exp 7) cm(exp -2) s(exp -1). Integrating the fraction of Lyc photons that escape the disk over our adopted luminosity function of OB associations, we estimate that approximately 7% of the ionizing photons, or Phi(sub Lyc) = 2.3 x 10(exp 6) cm(exp -2) s(exp -1), escape each side of the H I disk layer and penetrate the diffuse ionized medium ('Reynolds layer'). This flux is sufficient to explain the potoionization of this, although we have not constructed a model for the observed H-alpha emission and pulsar dispersion measures that is fully consistent with the absorption rate of Lyc in the H II layer. Since our quiescent model does not account for the effects of dynamic chimneys and superbubbles, which should enhance Lyc escape, we conclude the O stars are the probable source of ionizing radiation for the Reynolds layer. For a random distribution of OB associations throughout the disk, the Lyc flux is nearly uniform for heights Z is greater than approximately 0.8 kpc above the midplane.

  15. Radial velocities of a sample of ob stars in the Sco-Cen association

    NASA Astrophysics Data System (ADS)

    Jilinski, E.; de La Reza, R.; Cunha, K.

    2003-08-01

    Radial velocities (RV) were derived for a sample of OB stars belonging to Lower Centaurus Crux (LCC), Upper Centaurus Lupus (UCL) and Upper Scorpius (US) sub-groups of the Sco-Cen OB association. The knowledge of RV of OB stars of these sub-groups is important for membership determinations and the study of the past evolution and formation of these sub-groups. To measure RV of some stars belonging to the above mentioned sub-groups, 67 exposures of 56 stars were obtained between May 17, 2002 and July 7, 2002 with the 1.52 m ESO telescope equipped with FEROS echelle spectrograph (resolving power 48000 and spectral range 3550 - 9210 Å). RV were measured line by line. The cross-correlation technique is usually used for precise RV determinations of late type stars. Its application for the measurements of RV of OB stars can be problematical. On the one hand, spectra of early type stars show few absorption lines and these lines are intrinsically broad (up to a few hundreds km/sec). They are often broadened by stellar rotation and sometimes they also show variability. On the other hand, the cross-correlation peak is very broad and contains important sub-structures caused by the mixing of spectral lines of different widths. Moreover, a lot of OB stars are binaries and their broadened lines do not permit to observe them as double-lined binaries. The resulting mean values were compared with other observations in order to find new binary systems or to obtain more accurate RV for single stars. The values of the internal and external precisions of line by line measured RV are estimated as +/- 3.1 km/sec and +/- 5 km/sec. The results of these observations permitted us to recognize some stars (HD 120307, HD 116087, HD 139365 and HD 142990) as being probable spectral binaries due to their significant RV variations.

  16. Interstellar extinction toward the Cas OB6 association: Where is the dust?

    NASA Technical Reports Server (NTRS)

    Hanson, Margaret Murray; Clayton, Geoffrey C.

    1993-01-01

    We have completed a multiband (ultraviolet, optical, and near-infrared) study of the interstellar extinction properties of nine massive stars in IC 1805 and IC 1848, which are both part of Cas OB6 in the Perseus spiral arm. Our analysis includes determination of absolute extinction over the wavelength range from 3 micrometers to 1250 A. We have attempted to distinguish between foreground dust and dust local to Cas OB6. This is done by quantitatively comparing extinction laws of the least reddened sightlines (sampling mostly foreground dust) versus the most reddened sightlines (sampling a larger fraction of the dust in the Cas OB6 region). We have combined previous investigations to better understand the evolution of the interstellar medium in this active star forming region. We found no variation of extinction curve behavior between moderately reddend and heavily reddened Cas OB6 stars. None of the curves show any significant deviation from the Cardelli-Clayton-Mathis (CCM) R(sub upsilon)-dependent extinction. They are all consistent with that seen from diffuse dust. Most or all of the dust along the line of sight may be foreground to Cas OB6. Massive star forming regions can show significant deviations from CCM behavior which have been attributed to processing of the dust grains. Any dust local to the association must exist far from the hot stars in IC 1805 and IC 1848. A previous episode of star formation may have already cleared out the region of most of the gas and dust. Evidence for this can be seen in H I and IRAS data of the region.

  17. Improving Depression Treatment for Women: Integrating a Collaborative Care Depression Intervention into OB-GYN Care

    PubMed Central

    LaRocco-Cockburn, Anna; Reed, Susan D.; Melville, Jennifer; Croicu, Carmen; Russo, Joan; Inspektor, Michal; Edmondson, Eddie; Katon, Wayne

    2013-01-01

    Background Women have higher rates of depression and often experience depression symptoms during critical reproductive periods, including adolescence, pregnancy, postpartum, and menopause. Collaborative care intervention models for mood disorders in patients receiving care in an OB-GYN clinic setting have not been evaluated. Study design and methodology for a randomized, controlled trial of collaborative care depression management versus usual care in OB-GYN clinics and the details of the adapted collaborative care intervention and model implementation are described in this paper. Methods Women over age 18 years with clinically significant symptoms of depression, as measured by a Patient Health Questionnaire-9 (PHQ-9) score ≥10 and a clinical diagnosis of major depression or dysthymia, were randomized to the study intervention or to usual care and were followed for 18 months. The primary outcome assessed was change over time in the SCL-20 depression scale between baseline and 12 months. Baseline Results 205 women were randomized: 57% white, 20% African American, 9% Asian or Pacific Islander, 7% Hispanic, and 6% Native American. Mean age was 39 years. 4.6% were pregnant and 7.5% were within 12 months postpartum. The majority were single, (52%), and 95% had at least the equivalent of a high school diploma. Almost all patients met DSM IV criteria for major depression (99%) and approximately 33% met criteria for dysthymia. Conclusions An OB-GYN collaborative care team including a social worker, psychiatrist and OB-GYN physician who met weekly and used an electronic tracking system for patients were essential elements of the proposed depression care treatment model described here. Further study of models that improve quality of depression care that are adapted to the unique OB-GYN setting are needed. PMID:23939510

  18. ObsPy: A Python Toolbox for Seismology and Seismological Observatories

    NASA Astrophysics Data System (ADS)

    Krischer, Lion; Megies, Tobias; Barsch, Robert; Beyreuther, Moritz; Wassermann, Joachim

    2013-04-01

    Python combines the power of a full-blown programming language with the flexibility and accessibility of an interactive scripting language. Its extensive standard library and large variety of freely available high quality scientific modules cover most needs in developing scientific processing workflows. ObsPy extends Python's capabilities to fit the specific needs that arise when working with seismological data. It a) comes with a continuously growing signal processing toolbox that covers most tasks common in seismological analysis, b) provides read and write support for many common waveform, station and event metadata formats and c) enables access to various data centers, webservices and databases to retrieve waveform data and station/event metadata. In combination with mature and free Python packages like NumPy, SciPy, Matplotlib, IPython and PyQt, ObsPy makes it possible to develop complete workflows in Python, ranging from reading locally stored data or requesting data from one or more different data centers via signal analysis and data processing to visualization in GUI and web applications, output of modified/derived data and the creation of publication-quality figures. All functionality is extensively documented and the ObsPy Tutorial and Gallery give a good impression of the wide range of possible use cases. ObsPy is tested and running on Linux, OS X and Windows and comes with installation routines for these systems. ObsPy is developed in a test-driven approach and is available under the GPL/LGPLv3 open source licences. Users are welcome to request help, report bugs, propose enhancements or contribute code via either the user mailing list or the project page on GitHub.

  19. ObsPy: A Python Toolbox for Seismology - Recent Developments and Applications

    NASA Astrophysics Data System (ADS)

    Megies, T.; Krischer, L.; Barsch, R.; Sales de Andrade, E.; Beyreuther, M.

    2014-12-01

    ObsPy (http://www.obspy.org) is a community-driven, open-source project dedicated to building a bridge for seismology into the scientific Python ecosystem. It offersa) read and write support for essentially all commonly used waveform, station, and event metadata file formats with a unified interface,b) a comprehensive signal processing toolbox tuned to the needs of seismologists,c) integrated access to all large data centers, web services and databases, andd) convenient wrappers to legacy codes like libtau and evalresp.Python, currently the most popular language for teaching introductory computer science courses at top-ranked U.S. departments, is a full-blown programming language with the flexibility of an interactive scripting language. Its extensive standard library and large variety of freely available high quality scientific modules cover most needs in developing scientific processing workflows. Together with packages like NumPy, SciPy, Matplotlib, IPython, Pandas, lxml, and PyQt, ObsPy enables the construction of complete workflows in Python. These vary from reading locally stored data or requesting data from one or more different data centers through to signal analysis and data processing and on to visualizations in GUI and web applications, output of modified/derived data and the creation of publication-quality figures.ObsPy enjoys a large world-wide rate of adoption in the community. Applications successfully using it include time-dependent and rotational seismology, big data processing, event relocations, and synthetic studies about attenuation kernels and full-waveform inversions to name a few examples. All functionality is extensively documented and the ObsPy tutorial and gallery give a good impression of the wide range of possible use cases.We will present the basic features of ObsPy, new developments and applications, and a roadmap for the near future and discuss the sustainability of our open-source development model.

  20. Immunoneutralization of endogenous glucagon reduces hepatic glucose output and improves long-term glycemic control in diabetic ob/ob mice.

    PubMed

    Sørensen, Heidi; Brand, Christian L; Neschen, Susanne; Holst, Jens Juul; Fosgerau, Keld; Nishimura, Erica; Shulman, Gerald I

    2006-10-01

    In type 2 diabetes, glucagon levels are elevated in relation to the prevailing insulin and glucose levels. The relative hyperglucagonemia is linked to increased hepatic glucose output (HGO) and hyperglycemia. Antagonizing the effects of glucagon is therefore considered an attractive target for treatment of type 2 diabetes. In the current study, effects of eliminating glucagon signaling with a glucagon monoclonal antibody (mAb) were investigated in the diabetic ob/ob mouse. Acute effects of inhibiting glucagon action were studied by an oral glucose tolerance test (OGTT) and by measurement of HGO. In addition, the effects of subchronic (5 and 14 days) glucagon mAb treatment on plasma glucose, insulin, triglycerides, and HbA1c (A1C) levels were investigated. Glucagon mAb treatment reduced the area under the curve for glucose after an OGTT, reduced HGO, and increased the rate of hepatic glycogen synthesis. Glucagon mAb treatment for 5 days lowered plasma glucose and triglyceride levels, whereas 14 days of glucagon mAb treatment reduced A1C. In conclusion, acute and subchronic neutralization of endogenous glucagon improves glycemic control, thus supporting the contention that glucagon antagonism may represent a beneficial treatment of diabetes.

  1. Possible Detection of Pi(exp 0)-Decay Gamma-Ray Emission from Cyg OB2 by EGRET

    NASA Technical Reports Server (NTRS)

    Chen, W.; White, R. L.; Bertsch, D.

    1996-01-01

    We report possible detection of pi (exp 0) decay radiation from Cyg OB2, a nearby (1.7 kpc) massive OB star association. The EGRET flux (greater than 100 MeV) maps clearly indicate a point source whose error circle includes both Cyg OB2 and Cyg X-3. We show that Cyg X-3 is unlikely to be the counterpart for the EGRET source, because of the marginal spatial consistency and the lack of the 4.8 hour modulation seen in other high energy emissions from Cyg X-3. If confirmed, this will be the first detection by EGRET of massive stars.

  2. Red spectra of the brightest stars in Cygnus OB2 - Possible detection of two new interstellar bands

    NASA Astrophysics Data System (ADS)

    Torres-Dodgen, Ana V.

    1990-12-01

    The stellar and interstellar spectra of the 12 brightest stars in the Cygnus OB2 association are described. The observations were made in the wavelength range 5800 A-8500 A, at about 7 A resolution. Two new lines, centered near 7430 A and 7932 A, may be previously undetected interstellar bands. The former may be formed in the interstellar medium as well as in the dust environment of Cyg OB2, while the latter may be formed only in the dust environment of Cyg OB2.

  3. A Business Case Analysis (BCA) of the One Box - One Wire (OB1) Joint Combined Technology Demonstration (JCTD)

    DTIC Science & Technology

    2009-03-01

    BLDG A - SECRET Rei ana Below " Internet G Main Distribution Type-1 Frame ( MDF )Encryptor ••CIPR OB1 - SwitchNIPR Router B .,....UNCLASS Type-1 Router...Encryptor G OB1-PC G Switch Router Router Coalition Server SECRET RELFarm COALITION Enclave BLDG B - SECRET ana Below Router " MDF Switch " G B Server...Server Switch Below EnclaveFarm Router US Only SCIF BLDG C - TS/SCI and Below Switch Server Rm MDF ., OB1 - Switch G Router B ~~~~~torG " B" JWICS G Server

  4. A burst segmentation-deflection routing contention resolution mechanism in OBS networks

    NASA Astrophysics Data System (ADS)

    Guan, Ai-hong; Wang, Bo-yun

    2012-01-01

    One of the key problems to hinder the realization of optical burst switching (OBS) technology in the core networks is the losses due to the contention among the bursts at the core nodes. Burst segmentation is an effective contention resolution technique used to reduce the number of packets lost due to the burst losses. In our work, a burst segmentation-deflection routing contention resolution mechanism in OBS networks is proposed. When the contention occurs, the bursts are segmented according to the lowest packet loss probability of networks firstly, and then the segmented burst is deflected on the optimum routing. An analytical model is proposed to evaluate the contention resolution mechanism. Simulation results show that high-priority bursts have significantly lower packet loss probability and transmission delay than the low-priority. And the performance of the burst lengths, in which the number of segments per burst distributes geometrically, is more effective than that of the deterministically distributed burst lengths.

  5. Batch conversion of methane to methanol using Methylosinus trichosporium OB3b as biocatalyst.

    PubMed

    Hwang, In Yeub; Hur, Dong Hoon; Lee, Jae Hoon; Park, Chang-Ho; Chang, In Seop; Lee, Jin Won; Lee, Eun Yeol

    2015-03-01

    Recently, methane has attracted much attention as an alternative carbon feedstock since it is the major component of abundant shale and natural gas. In this work, we produced methanol from methane using whole cells of Methylosinus trichosporium OB3b as the biocatalyst. M. trichosporium OB3b was cultured on NMS medium with a supply of 7:3 air/methane ratio at 30°C. The optimal concentrations of various methanol dehydrogenase inhibitors such as potassium phosphate and EDTA were determined to be 100 and 0.5 mM, respectively, for an efficient production of methanol. Sodium formate (40 mM) as a reducing power source was added to enhance the conversion efficiency. A productivity of 49.0 mg/l·h, titer of 0.393 g methanol/l, and conversion of 73.8% (mol methanol/mol methane) were obtained under the optimized batch condition.

  6. BOREAS TGB-8 Photosynthetic Rate Data over the SSA-OBS and the SSA-OJP

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Conrad, Sara K. (Editor); Lerdau, Manuel

    2000-01-01

    The BOREAS TGB-8 team collected data to investigate the controls over NMHC fluxes from boreal forest tree species. This data set includes measurements of photosynthetic rates at mature jack pine and black spruce sites. The data were collected at the OJP and OBS tower flux locations in the BOREAS SSA. These areas contained mature stands of jack pine and black spruce and were the focal sites in the BOREAS program for studies of biosphere/atmosphere exchange from these two habitat types. The OBS site is situated in a black spruce/sphagnum bog with the largest trees 155 years old and 10-15 m tall. The OJP site is in a jack pine forest, 80 to 120 years old, which lies on a sandy bench of glacial outwash with the largest tree standing 15 m tall. Temporally, the data cover the period of 24-May-1994 to 19-Sep-1994. The data are stored in tabular ASCII files.

  7. BOREAS TF-3 Automated Chamber CO2 Flux Data from the NSA-OBS

    NASA Technical Reports Server (NTRS)

    Goulden, Michael L.; Crill, Patrick M.; Hall, Forrest G. (Editor); Conrad, Sara (Editor)

    2000-01-01

    The BOReal Ecosystem Atmosphere Study Tower Flux (BOREAS TF-3) and Trace Gas Biogeochemistry (TGB-1) teams collected automated CO2 chamber flux data in their efforts to fully describe the CO2 flux at the Northern Study Area-Old Black Spruce (NSA-OBS) site. This data set contains fluxes of CO2 at the NSA-OBS site measured using automated chambers. In addition to reporting the CO2 flux, it reports chamber air temperature, moss temperature, and light levels during each measurement. The data set covers the period from 23-Sep-1995 through 26-Oct-1995 and from 28-May-1996 through 21-Oct-1996. The data are stored in tabular ASCII files.

  8. OB-Rb gene transfer to leptin-resistant islets reverses diabetogenic phenotype

    PubMed Central

    Wang, May-Yun; Koyama, Kazunori; Shimabukuro, Michio; Newgard, Christopher B.; Unger, Roger H.

    1998-01-01

    In obese Zucker diabetic fatty (ZDF) rats with mutant leptin receptors, pancreatic islets have an ≈50-fold increase in fat (TG), overproduce nitric oxide (NO), and lack a normal proinsulin mRNA response to fatty acids. We overexpressed the wild-type full-length “b” isoform of the leptin receptor (OB-Rb) in ZDF islets by perfusing ZDF pancreata with recombinant adenovirus containing the cDNA encoding OB-Rb. In cultured islets isolated from these animals, leptin lowered islet TG by 87% and completely blocked TG formation from free fatty acids. Overproduction of NO was reduced, and the preproinsulin mRNA response to free fatty acids was restored. This establishes defective leptin action as the proximate cause of lipotoxic diabetes in ZDF rats. PMID:9435258

  9. The Copper Chelator Methanobactin from Methylosinus Trichosporium OB3b Binds Copper(I)

    SciTech Connect

    Hakemian,A.; Tinberg, C.; Kondapali, K.; Tesler, J.; Hoffman, B.; Stemmler, T.; Rosenzweig, A.

    2005-01-01

    The oxidation state of copper bound to methanobactin, a small siderophore-like molecule from the methanotroph Methylosinus trichosporium OB3b, was investigated. Purified methanobactin loaded with Cu(II) exhibits a weak EPR signal probably due to adventitious Cu(II). The EPR signal intensity increases significantly upon addition of the strong oxidant nitric acid. Features of the X-ray absorption near edge spectrum, including a 1s {yields} 4p transition at 8985 eV, further indicate the presence of Cu(I). EXAFS data were best fit using a multiple scattering model generated from previously reported crystallographic parameters. These results establish definitively that M. trichosporium OB3b methanobactin binds Cu(I) and suggest that methanobactin itself reduces Cu(II) to Cu(I).

  10. Proposal of a multi-layer network architecture for OBS/GMPLS network interworking

    NASA Astrophysics Data System (ADS)

    Guo, Hongxiang; Tsuritani, Takehiro; Yin, Yawei; Otani, Tomohiro; Wu, Jian

    2007-11-01

    In order to enable the existing optical circuit switching (OCS) network to support both wavelength and subwavelength granularities, this paper proposes overlay-based multi-layer network architecture for interworking the generalized multi-protocol label switching (GMPLS) controlled OCS network with optical burst switching (OBS) networks. A dedicated GMPLS border controller with necessary GMPLS extensions, including group label switching path (LSP) provisioning, node capability advertisement, and standard wavelength label as well as wavelength availability advertisement, is introduced in this multi-layer network to enable a simple but flexible interworking operation. The feasibility of this proposal is experimentally confirmed by demonstrating an OBS/GMPLS testbed, in which the extended node capability advertisement and group LSP functions successfully enabled the burst header packet (BHP) and data burst (DB) to transmit over a GMPLS-controlled transparent OCS network.

  11. ARA OB1 - A stellar association formed by the action of an energetic event?

    NASA Astrophysics Data System (ADS)

    Arnal, E. M.; Cersosimo, J. C.; May, J.; Bronfman, L.

    1987-03-01

    Neutral hydrogen (at λ = 21 cm) and carbon monoxide (at λ = 2.6 mm) line observations of the interstellar medium in the neighbourhood of the association Ara OB1 are reported. The observed H I distribution indicates the presence of an expanding structure. The total H I mass associated with such feature amounts to 4800 solar masses, and its momentum and kinetic energy are ≡4×104M_sun; km s-1 and 3×1048erg, respectively. The H I structure, 42 pc in diameter, expands at a speed of 10 km s-1. A possible origin for the expanding H I structure, and a genetic link between such structure and Ara OB1 are proposed.

  12. ObStruct: a method to objectively analyse factors driving population structure using Bayesian ancestry profiles.

    PubMed

    Gayevskiy, Velimir; Klaere, Steffen; Knight, Sarah; Goddard, Matthew R

    2014-01-01

    Bayesian inference methods are extensively used to detect the presence of population structure given genetic data. The primary output of software implementing these methods are ancestry profiles of sampled individuals. While these profiles robustly partition the data into subgroups, currently there is no objective method to determine whether the fixed factor of interest (e.g. geographic origin) correlates with inferred subgroups or not, and if so, which populations are driving this correlation. We present ObStruct, a novel tool to objectively analyse the nature of structure revealed in Bayesian ancestry profiles using established statistical methods. ObStruct evaluates the extent of structural similarity between sampled and inferred populations, tests the significance of population differentiation, provides information on the contribution of sampled and inferred populations to the observed structure and crucially determines whether the predetermined factor of interest correlates with inferred population structure. Analyses of simulated and experimental data highlight ObStruct's ability to objectively assess the nature of structure in populations. We show the method is capable of capturing an increase in the level of structure with increasing time since divergence between simulated populations. Further, we applied the method to a highly structured dataset of 1,484 humans from seven continents and a less structured dataset of 179 Saccharomyces cerevisiae from three regions in New Zealand. Our results show that ObStruct provides an objective metric to classify the degree, drivers and significance of inferred structure, as well as providing novel insights into the relationships between sampled populations, and adds a final step to the pipeline for population structure analyses.

  13. Alma Observations Of Circumstellar Disks In The Upper Scorpius Ob Association

    NASA Astrophysics Data System (ADS)

    Barenfeld, Scott

    2016-07-01

    We present ALMA observations of 106 G-, K-, and M-type stars in the Upper Scorpius OB Association hosting circumstellar disks. With these data, we measure the total dust masses of these disks. We find that disk dust masses in Upper Scorpius are a factor of 4.5 times lower than those in the younger Taurus star forming region, clear evidence of disk evolution between 1-2 Myr and 5-10 Myr.

  14. Communities of bacteria and viruses in waters of the Gulf of Ob and Taz Estuary.

    PubMed

    Pavlova, M A; Makarevich, P R; Shirokolobova, T I

    2016-11-01

    The study of the most abundant components in freshwater plankton in the Gulf of Ob and Taz Estuary in the summer-autumn season has demonstrated that the abundance and biomass of bacteria are stable and typical for mesotrophic waters during active microalgae vegetation. The abundance of viral particles varies in the range which is reported for unproductive or medium-productive water bodies. The environmental factors affecting affect the development and patterns of bacterio- and virioplankton distribution are considered.

  15. A Mathematical Model for the Reduction Stage of the CAS-OB Process

    NASA Astrophysics Data System (ADS)

    Sulasalmi, Petri; Visuri, Ville-Valtteri; Kärnä, Aki; Järvinen, Mika; Ollila, Seppo; Fabritius, Timo

    2016-12-01

    This paper proposes a novel method for modeling the reduction stage of the CAS-OB process (composition adjustment by sealed argon bubbling-oxygen blowing). Our previous study proposed a model for the heating stage of the CAS-OB process; the purpose of the present study is to extend this work toward a more comprehensive model for the process in question. The CAS-OB process is designed for homogenization and control of the composition and temperature of steel. During the reduction stage, the steel phase is stirred intensely by employing the gas nozzles at the bottom of the ladle, which blow argon gas. It is assumed that the reduction rate of the top slag is dictated by the formation of slag droplets at the steel-slag interface. Slag droplets, which are generated due to turning of the steel flow in the spout, contribute mainly by increasing the interfacial area between the steel and slag phases. This phenomenon has been taken into account based on our previous study, in which the droplet size distribution and generation rate at different steel flow velocities. The reactions considered between the slag and steel phases are assumed to be mass transfer controlled and reversible. We validated the results from the model against the measurements from the real CAS-OB process. The results indicate that the model accurately predicts the end compositions of slag and steel. Moreover, it was discovered that the cooling rate of steel during the gas stirring given by the model is consistent with the results reported in the literature.

  16. Escape fraction of ionizing photons during reionization: Effects due to supernova feedback and runaway ob stars

    SciTech Connect

    Kimm, Taysun; Cen, Renyue

    2014-06-20

    The fraction of hydrogen ionizing photons escaping from galaxies into the intergalactic medium is a critical ingredient in the theory of reionization. We use two zoomed-in, high-resolution (4 pc), cosmological radiation hydrodynamic simulations with adaptive mesh refinement to investigate the impact of two physical mechanisms (supernova, SN, feedback, and runaway OB stars) on the escape fraction (f {sub esc}) at the epoch of reionization (z ≥ 7). We implement a new, physically motivated SN feedback model that can approximate the Sedov solutions at all (from the free expansion to snowplow) stages. We find that there is a significant time delay of about ten million years between the peak of star formation and that of escape fraction, due to the time required for the build-up and subsequent destruction of the star-forming cloud by SN feedback. Consequently, the photon number-weighted mean escape fraction for dwarf galaxies in halos of mass 10{sup 8}-10{sup 10.5} M {sub ☉} is found to be 〈f{sub esc}〉∼11%, although instantaneous values of f {sub esc} > 20% are common when star formation is strongly modulated by the SN explosions. We find that the inclusion of runaway OB stars increases the mean escape fraction by 22% to 〈f{sub esc}〉∼14%. As SNe resulting from runaway OB stars tend to occur in less dense environments, the feedback effect is enhanced and star formation is further suppressed in halos with M{sub vir}≳10{sup 9} M{sub ⊙} in the simulation with runaway OB stars compared with the model without them. While both our models produce enough ionizing photons to maintain a fully ionized universe at z ≤ 7 as observed, a still higher amount of ionizing photons at z ≥ 9 appears necessary to accommodate the high observed electron optical depth inferred from cosmic microwave background observations.

  17. The large scale view of the young stellar populations in the Orion OB1 Association

    NASA Astrophysics Data System (ADS)

    Briceno, Cesar; Calvet, Nuria

    2016-06-01

    The Orion OB1 association, at ~400 pc and with a wide range of ages (~1-10 Myr) and environmental conditions, is an ideal place to look at how stars form, first evolve and disperse among the general population of field stars. Also to study disk dispersal and the duration of the planet formation phase.However, despite spanning nearly 200 deg2 on the sky, almost all we know about Orion comes from studies of a limited fraction of the entire region, mostly of the youngest objects (~<1 Myr) in the A and B molecular clouds and the ~3 Myr old sigma Ori cluster.We will present here the results of our 180 sq deg photometric multi-epoch survey across the Orion OB1 association, using the known variability of T Tauri stars to pick them among the general field population, and following with spectroscopy to confirm members and characterize them.The ~2000 newly identified young low-mass stars are mostly located away from the molecular clouds, across tens of sq. deg. in the Orion OB1a and OB1b sub-associations, with ages in the range ~4-10 Myr. But within this general population we identify a significant fraction concentrated in distinct overdensities, most notably the ~7 Myr old 25 Orionis cluster. These stellar aggregates point to a previously unknown degree of substructure that has survived the dissipation of the parent molecular clouds. We also find that the Orion Nebula Cluster is surrounded by a few sq.deg. halo of young stars, as has been suggested by recent sudies.

  18. On the nature of high reddening of Cygnus OB2 #12 hypergiant

    NASA Astrophysics Data System (ADS)

    Maryeva, O. V.; Chentsov, E. L.; Goranskij, V. P.; Dyachenko, V. V.; Karpov, S. V.; Malogolovets, E. V.; Rastegaev, D. A.

    2016-05-01

    To explain the nature of the high reddening (AV ≃ 10 mag) towards one of the most luminous stars in the Galaxy - Cyg OB2 #12 (B5 Ia-0), also known as MT304, we carried out spectrophotometric observations of 24 stars located in its vicinity. We included five new B-stars among the members of Cygnus OB2, and for five more photometrically selected stars we spectroscopically confirmed their membership. We constructed the map of interstellar extinction within 2.5 arcmin radius and found that interstellar extinction increases towards MT304. According to our results the most reddened OB-stars in the association after MT304 are J203240.35+411420.1 and J203239.90+411436.2, located about 15 arcsec away from it. Interstellar extinction towards these stars is about 9 mag. The increase of reddening towards MT304 suggests that the reddening excess may be caused by the circumstellar shell ejected by the star during its evolution. This shell absorbs 1 mag, but its chemical composition and temperature are unclear. We also report the detection of a second component of MT304, and discovery of an even fainter third component, based on data of speckle interferometric observations taken with the Russian 6-m telescope.

  19. High Resolution Spectroscopy of C_2 and CN in the Cygnus OB2 Association

    NASA Astrophysics Data System (ADS)

    McCall, Benjamin J.; Oka, Takeshi

    2000-08-01

    The unexpected detection of a large column density of hhh along the lines of sight to Cygnus OB2 #12 and Cygnus OB2 #5 cannot be explained by the standard models of diffuse cloud chemistry, which imply unreasonably long absorption path lengths (hundreds of parsecs). In order to gather more information about the physical condition of the diffuse gas in these lines of sight, we propose to obtain high resolution (R 120 000) visible spectra of several stars in the Cygnus OB2 association, including #12 and #5. The observed rotational distribution of the diatomics çand CN will enable us to estimate the kinetic temperature and number density of the molecular gas. In addition, the high resolution of the HRS at HET will allow us to study the velocity distribution of both the atomic (K I) and molecular (çand CN) gas along these lines of sight. Together with our previous observations of hhh, the temperatures, number densities, and velocity distributions from the proposed observations will seriously constrain theoretical models of these sightlines, such as that recently proposed by Cecchi-Pestellini and Dalgarno.

  20. Diacylglycerol production induced by growth hormone in Ob1771 preadipocytes arises from phosphatidylcholine breakdown

    SciTech Connect

    Catalioto, R.M.; Ailhaud, G.; Negrel, R. )

    1990-12-31

    Growth Hormone has recently been shown to stimulate the formation of diacylglycerol in Ob1771 mouse preadipocyte cells without increasing inositol lipid turnover. Addition of growth hormone to Ob1771 cells prelabelled with ({sup 3}H)glycerol or ({sup 3}H)choline led to a rapid, transient and stoechiometric formation of labelled diacylglycerol and phosphocholine, respectively. In contrast, no change was observed in the level of choline and phosphatidic acid whereas the release of water-soluble metabolites in ({sup 3}H)ethanolamine prelabelled cells exposed to growth hormone was hardly detectable. Stimulation by growth hormone of cells prelabelled with (2-palmitoyl 9, 10 ({sup 3}H))phosphatidylcholine also induced the production of labelled diacyglycerol. Pertussis toxin abolished both diacylglycerol and phosphocholine formation induced by growth hormone. It is concluded that growth hormone mediates diacylglycerol production in Ob1771 cells by means of phosphatidylcholine breakdown involving a phospholipase C which is likely coupled to the growth hormone receptor via a pertussis toxin-sensitive G-protein.

  1. CLUSTERING BETWEEN HIGH-MASS X-RAY BINARIES AND OB ASSOCIATIONS IN THE MILKY WAY

    SciTech Connect

    Bodaghee, A.; Tomsick, J. A.; Rodriguez, J.

    2012-01-10

    We present the first direct measurement of the spatial cross-correlation function of high-mass X-ray binaries (HMXBs) and active OB star-forming complexes in the Milky Way. This result relied on a sample containing 79 hard X-ray-selected HMXBs and 458 OB associations. Clustering between the two populations is detected with a significance above 7{sigma} for distances <1 kpc. Thus, HMXBs closely trace the underlying distribution of the massive star-forming regions that are expected to produce the progenitor stars of HMXBs. The average offset of 0.4 {+-} 0.2 kpc between HMXBs and OB associations is consistent with being due to natal kicks at velocities of the order of 100 {+-} 50 km s{sup -1}. The characteristic scale of the correlation function suggests an average kinematical age (since the supernova phase) of {approx}4 Myr for the HMXB population. Despite being derived from a global view of our Galaxy, these signatures of HMXB evolution are consistent with theoretical expectations as well as observations of individual objects.

  2. Galactic OB associations in the northern Milky Way Galaxy. I - Longitudes 55 deg to 150 deg

    NASA Technical Reports Server (NTRS)

    Garmany, C. D.; Stencel, R. E.

    1992-01-01

    The literature on all OB associations was reviewed, and their IRAS point source content was studied, between galactic longitude 55 and 150 deg. Only one third of the 24 associations listed by Ruprecht et al. (1981) have been the subject of individual studies designed to identify the brightest stars. Distances to all of these were recomputed using the method of cluster fitting of the B main sequence stars, which makes it poossible to reexamine the absolute magnitude calibration of the O stars, as well as for the red supergiant candidate stars. Also examined was the composite HR diagram for these associations. Associations with the best defined main sequences, which also tend to contain very young clusters, referred to here as OB clusters, have extremely few evolved B and A or red supergiants. Associations with poorly defined main sequences and few OB clusters have many more evolved stars. They also show an effect in the upper HR diagram referred to as a ledge by Fitzpatrick and Garmany (1990) in similar data for the Large Magellanic Cloud. It is suggested that the differences in the associations are not just observational selection effects but represent real differences in age and formation history.

  3. A model for the infrared emission from an OB star cluster environment

    NASA Technical Reports Server (NTRS)

    Leisawitz, D.

    1990-01-01

    Researchers developed an interactive radiative transfer code that predicts the infrared emission from an HII region containing diffuse ionized and atomic gas and dense molecular clouds. This model complements the investigation of the redistribution of OB star luminosity in the interstellar medium (Leisawitz and Hauser 1988, Ap. J., 332, 954). The model can be used as a diagnostic tool to probe the radiation field and matter density in an HII region, place constraints on the proximity and orientation of an illuminated molecular cloud with respect to the ionizing stars, test for the presence of small, transiently heated dust grains, and determine whether the dust-to-gas ratio is normal. Predictions of the model agree qualitatively and quantitatively with observations of blister-type HII regions ionized by well-studied OB clusters in which the distribution of dense neutral material is known. This is illustrated by a model for Infrared Astronomy Satellite (IRAS) observations of the region around NGC 7380 (S142). Researchers plan to use the model in a survey of regions of massive star formation in the outer Galaxy to study OB stars embedded to various degrees in their parental molecular clouds.

  4. Large Scale Variability Surveys from Venezuela: Orion OB1 and beyond

    NASA Astrophysics Data System (ADS)

    Briceño, C.; Calvet, N.; Vivas, A. K.; Hartmann, L.

    We present our scheme and initial results for variability surveys spanning hundreds of square degrees near the celestial equator, carried out with an 8k x 8k CCD Mosaic Camera optimized for drift-scanning, installed on the 1m Schmidt telescope at the Venezuela National Astronomical Observatory. In the Orion OB1 association, one of the nearest and most active regions of star formation, we are conducting a 120 sqr.deg. VRIHalpha survey to map the low mass young stellar population in this region. The absence of dust and gas around the young stars in the ˜ 10 Myr Ori OB 1a sub-association suggests that star formation is a rapid process, and that molecular clouds do not last more than a few million years after the first stars are born. The lack of accretion indicators or near IR emission from inner dusty disks among stars in Ori OB 1a suggests that significant disk dissipation has occurred in a few Myr, possibly due to the coagulation/agglomeration of dust particles into larger bodies like planetesimals or planets. The results of our variability surveys will be made available through a massive database equipped with web-based data mining tools, as part of the effort leading to the International Virtual Observatory.

  5. VizieR Online Data Catalog: Deep OB star population in Carina (Mohr-Smith+, 2017)

    NASA Astrophysics Data System (ADS)

    Mohr-Smith, M.; Drew, J. E.; Napiwotzki, R.; Simon-Diaz, S.; Wright, N. J.; Barentsen, G.; Eisloeffel, J.; Farnhill, H. J.; Greimel, R.; Monguio, M.; Kalari, V.; Parker, Q. A.; Vink, J. S.

    2016-11-01

    The sky positions and photometric measurements from VPHAS+ (and 2MASS) for 14900 candidate OB stars blue-selected from the Carina region of the Galactic plane are set out in the first 24 columns. The optical magnitudes are expressed in the Vega system. These are followed by the parameters and their error estimates obtained from main-sequence fits to the optical/NIR magnitudes, along with the chi-squared measure of goodness of fit (columns 25 to 33). For the 3 degrees of freedom involved, chi-squared values up to 7.82 may be regarded as 'good fits': 5915 objects are good fits in this sense and have estimated effective temperatures high enough to place them into the O-B2 range. The fitting process delivers effective temperatures, (highly uncertain) distance moduli, and the extinction parameters, A0 and RV. Subsequent columns (34 to 37) identify which candidates are: good O-B2 fits; likely to be emission line stars (based on r-Halpha excess); candidate sub-luminous stars; candidate higher-luminosity evolved objects. The 'Notes' in column 38 provide information on cross-identifications to known objects, where these exist. Columns 39 to 49 present spectroscopically-derived parameters and associated errors for the subset of 276 stars with spectra. (1 data file).

  6. Photometric Survey of Intermediate Mass Members of the Orion OB1 Association

    NASA Astrophysics Data System (ADS)

    Sherry, William; Walter, Frederick; Brittain, Sean; Kim, Jinyoung Serena

    2009-08-01

    We propose to survey 15 deg^2 of the OB1a and OB1b groups of the Orion OB1 association to measure UBVRI photometry of high and intermediate mass members of the association. This survey will address two goals. First, it will extend the photometric coverage of association members to cover the full spectrum of masses between 0.01 M_⊙ and 40 M_⊙ - extant photometry misses most stars in the range 1 M_⊙ to 3 M_⊙ (10

  7. B fields in OB stars (BOB): Concluding the FORS 2 observing campaign

    NASA Astrophysics Data System (ADS)

    Schöller, M.; Hubrig, S.; Fossati, L.; Carroll, T. A.; Briquet, M.; Oskinova, L. M.; Järvinen, S.; Ilyin, I.; Castro, N.; Morel, T.; Langer, N.; Przybilla, N.; Nieva, M.-F.; Kholtygin, A. F.; Sana, H.; Herrero, A.; Barbá, R. H.; de Koter, A.; BOB Collaboration

    2017-03-01

    Aims: The B fields in OB stars (BOB) Collaboration is based on an ESO Large Programme to study the occurrence rate, properties, and ultimately the origin of magnetic fields in massive stars. Methods: In the framework of this program, we carried out low-resolution spectropolarimetric observations of a large sample of massive stars using FORS 2 installed at the ESO VLT 8 m telescope. Results: We determined the magnetic field values with two completely independent reduction and analysis pipelines. Our in-depth study of the magnetic field measurements shows that differences between our two pipelines are usually well within 3σ errors. From the 32 observations of 28 OB stars, we were able to monitor the magnetic fields in CPD -57° 3509 and HD 164492C, confirm the magnetic field in HD 54879, and detect a magnetic field in CPD -62° 2124. We obtain a magnetic field detection rate of 6 ± 3% for the full sample of 69 OB stars observed with FORS 2 within the BOB program. For the preselected objects with a v sin i below 60 km s-1, we obtain a magnetic field detection rate of 5 ± 5%. We also discuss X-ray properties and multiplicity of the objects in our FORS 2 sample with respect to the magnetic field detections. Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under program ID 191.D-0255(E,G).

  8. CHARACTERIZATION OF THE YOUNG OPEN CLUSTER G144.9+0.4 IN THE CAMELOPARDALIS OB1 ASSOCIATION

    SciTech Connect

    Lin, Chien-Cheng; Chen, W. P.; Panwar, Neelam

    2013-10-01

    Our star-count analysis of the Two Micron All Sky Survey point sources resulted in an identification of the star cluster G144.9+0.4. The cluster was found, but not characterized, by Glushkova et al. We show that the cluster is physically associated with the Cam OB1 association at a distance of about 1 kpc and with an age of 1-2 Myr. Pre-main sequence stars are identified on the basis of photometric and proper motion data. A total of 91 additional OB star candidates was found in subgroups 1A and 1B, a significant increase from the currently known 43 OB stars. The OB members show an age spread that indicates a sustained star formation for at least the last 10-15 Myr. The young cluster G144.9+0.4 represents the latest episode of sequential star formation in this cloud complex.

  9. 25 Orionis: A Kinematically Distinct 10 Myr Old Group in Orion OB1a

    NASA Astrophysics Data System (ADS)

    Briceño, César; Hartmann, Lee; Hernández, Jesús; Calvet, Nuria; Vivas, A. Katherina; Furesz, Gabor; Szentgyorgyi, Andrew

    2007-06-01

    We report here on the photometric and kinematic properties of a well-defined group of nearly 200 low-mass pre-main-sequence stars, concentrated within ~1° of the early-B star 25 Ori, in the Orion OB1a subassociation. We refer to this stellar aggregate as the 25 Orionis group. The group also harbors the Herbig Ae/Be star V346 Ori and a dozen other early-type stars with photometry, parallaxes, and some with IR excess emission, indicative of group membership. The number of high- and low-mass stars is in agreement with expectations from a standard initial mass function. The velocity distribution for the low-mass stars shows a narrow peak at 19.7 km s-1, offset ~-10 km s-1 from the velocity characterizing the younger stars of the Ori OB1b subassociation, and -4 km s-1 from the velocity of widely spread young stars of the Ori OB1a population; this result provides new and compelling evidence that the 25 Ori group is a distinct kinematic entity, and that considerable space and velocity structure is present in the Ori OB1a subassociation. The low-mass members follow a well-defined band in the color-magnitude diagram, consistent with an isochronal age of ~7-10 Myr. The ~2 time drop in the overall Li I equivalent widths and accretion fraction between the younger Ori OB1b and the 25 Ori group is consistent with the latter being significantly older. In a simple-minded kinematic evolution scenario, the 25 Ori group may represent the evolved counterpart of the younger σ Ori cluster. The 25 Ori stellar aggregate is the most populous ~10 Myr sample yet known within 500 pc, setting it as an excellent laboratory to study the evolution of solar-like stars and protoplanetary disks. Based on observations obtained at the Llano del Hato National Astronomical Observatory of Venezuela, operated by CIDA for the Ministerio de Ciencia y Tecnología the MMT Observatory, a joint facility of the Smithsonian Institution and the University of Arizona; and the Fred Lawrence Whipple Observatory of

  10. OB stars at the lowest Local Group metallicity. GTC-OSIRIS observations of Sextans A

    NASA Astrophysics Data System (ADS)

    Camacho, I.; Garcia, M.; Herrero, A.; Simón-Díaz, S.

    2016-01-01

    Context. Massive stars play an important role in the chemical and dynamical evolution of the Universe. The first metal-poor stars may have started the reionization of the Universe. To understand these early epochs it is necessary to know the behavior and the physical properties of massive stars in very metal-poor environments. We focus on the massive stellar content of the metal-poor irregular galaxy Sextans A. Aims: Our aim is to find and classify OB stars in Sextans A, so as to later determine accurate stellar parameters of these blue massive stars in this low-metallicity region (Z ~ 0.1 Z⊙). Methods: Using UBV photometry, the reddening-free index Q and GALEX imaging, we built a list of blue massive star candidates in Sextans A. We obtained low-resolution (R ~ 1000) GTC-OSIRIS spectra for a fraction of them and carried out spectral classification. For the confirmed O-stars, we derived preliminary stellar parameters. Results: The target selection criteria and observations were successful and have produced the first spectroscopic atlas of OB-type stars in Sextans A. From the whole sample of 18 observed stars, 12 were classified as early OB-types, including 5 O-stars. The radial velocities of all target stars are in agreement with their Sextans A membership, although three of them show significant deviations. We determined the stellar parameters of the O-type stars using the stellar atmosphere code FASTWIND and revisited the sub-SMC temperature scale. Two of the O-stars are consistent with relatively strong winds and enhanced helium abundances, although results are not conclusive. We discuss the position of the OB stars in the HRD. Initial stellar masses run from slightly below 20 up to 40 solar masses. Conclusions: The target selection method worked well for Sextans A. The stellar temperatures are consistent with findings in other galaxies. Some of the targets deserve follow-up spectroscopy because of indications of a runaway nature, an enhanced helium abundance

  11. MUG-OBS - Multiparameter Geophysical Ocean Bottom System : a new instrumental approach to monitor earthquakes.

    NASA Astrophysics Data System (ADS)

    Hello, Y.; Yegikyan, M.; Charvis, P.; Verfaillie, R.; Philippe, O.

    2015-12-01

    There are several attempts to monitor real time seismic activity, using regional scale wired nodes, such as Neptune in Canada and in the U.S, Antares in France or DONET in Japan.On another hand there are also initiatives in deploying repeatedly OBS array like during the amphibious Cascadia Initiative (four 1-year deployments), the Japanese Pacific Array (broadband OBSs "ocean-bottom broadband dispersion survey" with 2-years autonomy), the Obsismer program in the French Lesser Antilles (eight 6-months deployments) and the Osisec program in Ecuador (four 6-months deployments). These OBSs are autonomous, they are self-recovered or recovered using an ROV. These systems are costly including ship time, and require to recover the OBS before to start working on data.Among the most recent alternative we developed a 3-years autonomy OBS equipped with a Nanometrics Trillium 120 s, a triaxial accelerometer, a differential, an absolute pressure gauge, and a hydrophone. MUG-OBS is a free falling instrument rated down to 6000 m. The installation of the sensor is monitored by acoustic commands from the surface and a health bulletin with data checking is recovered by acoustic during the installation. The major innovation is that it is possible to recover the data any time on demand (regularly every 6-months or after a seismic crisis) utilizing one of the 6 data-shuttles released from the surface by acoustic command using a one day fast cruise boat of opportunity. Since sensors stayed at the same location for 3 years (when an OBS is redeployed on the same site, it will not land in the same place), it is a perfect tool to monitor slow seismic events, background seismic activity and aftershock distribution. Clock, drift measurement and GPS localization is automatic when the shuttle reaches the surface. A new version is being developed; for remote areas, shuttles released automatically and a seismic events bulletin is transmitted. Selected data can be recovered by two- way Iridium

  12. Integration of a permanent OBS offshore NE Iberian Peninsula to the Catalan Seismic Network

    NASA Astrophysics Data System (ADS)

    Frontera, T.; Olivera, C.; Jara, J. A.; Goula, X.; Ugalde, A.

    2009-04-01

    On August 2005 a permanent ocean bottom seismometer (OBS) and a differential pressure gauge (DPG) were installed inside the security perimeter of the Casablanca oil platform (40 km offshore Tarragona, NE Spain), within the framework of a project which has the aim of improving the knowledge of the seismicity and seismic risk in the region. This project is being carried out by the Institut Geològic de Catalunya (IGC) and the Observatori de l'Ebre, in collaboration with the Spanish oil company Repsol Investigaciones Petrolíferas. The sensors were submerged at about 400 m to the SW of the oil platform and were deposited at about 150 m in depth. Data are digitized on-site and are transmitted through a submarine cable to the platform, where they are recorded. In July 2007 via satellite signal transmission was implemented to have continuous and real time data, which allowed integrating the OBS into the Catalan Seismic Network. Since 1999 the objectives of the Catalan Seismic Network are, on the one hand, providing rapid information for Civil Defence Services and society in general and, on the other hand, to obtain systematically high quality data for the scientific community. This real time system is based on a VSAT seismic network and it has been implemented in Catalonia (Spain) by the IGC. The project of the network was planned to create robust, high performance field infrastructures through the installation of up to 21 stations equipped with three component broad band sensors and a high dynamic range and it has been developed in several steps. In 2009, 18 stations are operative: 14 broad band and 3 accelerometers on land and one broad band OBS. The stations are based on VSAT platforms that are transmitting continuously almost real time seismic data via satellite to the IGC hub. Once at seismic data reception centre data are continuously archived and processed with an automatic system. A study of the OBS signal in terms of noise has been made and compared to the

  13. VizieR Online Data Catalog: Properties of OB associations in IC 1613 (Garcia+, 2010)

    NASA Astrophysics Data System (ADS)

    Garcia, M.; Herrero, A.; Castro, N.; Corral, L.; Rosenberg, A.

    2014-06-01

    To understand the structure and evolution of massive stars, systematic surveys of the Local Group galaxies have been undertaken, to find these objects in environments of different chemical abundances. We focus on the metal-poor irregular galaxy IC 1613 to analyze the stellar and wind structure of its low-metallicity massive stars. We ultimately aim to study the metallicity-dependent driving mechanism of the winds of blue massive stars and use metal-poor massive stars of the Local Volume as a proxy for the stars in the early Universe. In a previous paper we produced a list of OB associations in IC 1613. Their properties are not only a powerful aid towards finding the most interesting candidate massive stars, but also reveal the structure and recent star formation history of the galaxy. We characterize these OB associations and study their connection with the galactic global properties. The reddening-free Q parameter is a powerful tool in the photometric analysis of young populations of massive stars, since it exhibits a smaller degree of degeneracy with OB spectral types than the B-V color. The color-magnitude diagram (Q vs. V) of the OB associations in IC 1613 is studied to determine their age and mass, and confirm the population of young massive stars. We identified more than 10 stars with M>=50M⊙. Spectral classification available for some of them confirm their massive nature, yet we find the common discrepancy with the spectroscopically derived masses. There is a general increasing trend of the mass of the most massive member with the number of members of each association, but not with the stellar density. The average diameter of the associations of this catalog is 40pc, half the historically considered typical size of OB associations. Size increases with the association population. The distribution of the groups strongly correlates with that of neutral and ionized hydrogen. We find the largest dispersion of association ages in the bubble region of the galaxy

  14. Increased hepatic oxidative metabolism distinguishes the action of Peroxisome proliferator-activated receptor δ from Peroxisome proliferator-activated receptor γ in the ob/ob mouse

    PubMed Central

    2009-01-01

    Background The peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors and members of the nuclear receptor superfamily. The PPAR family consists of three members: PPARα, PPARγ, and PPARδ. PPARδ controls the transcription of genes involved in multiple physiological pathways, including cellular differentiation, lipid metabolism and energy homeostasis. The receptor is expressed almost ubiquitously, with high expression in liver and skeletal muscle. Although the physiological ligands of PPARδ remain undefined, a number of high affinity synthetic ligands have been developed for the receptor as a therapeutic target for type 2 diabetes mellitus, dyslipidemia and the metabolic syndrome. Methods In this study, the metabolic role of PPARδ activation has been investigated in liver, skeletal muscle, blood serum and white adipose tissue from ob/ob mice using a high affinity synthetic ligand and contrasted with PPARγ activation. To maximize the analytical coverage of the metabolome, 1H-nuclear magnetic resonance (1H-NMR) spectroscopy, gas chromatography-mass spectrometry (GC-MS) and ultra performance liquid chromatography-mass spectrometry (UPLC-MS) were used to examine metabolites from tissue extracts. Results Analysis by multivariate statistics demonstrated that PPARδ activation profoundly affected glycolysis, gluconeogenesis, the TCA cycle and linoleic acid and α-linolenic acid essential fatty acid pathways. Conclusions Although activation of both PPARδ and PPARγ lead to increased insulin sensitivity and glucose tolerance, PPARδ activation was functionally distinct from PPARγ activation, and was characterized by increased hepatic and peripheral fatty acid oxidative metabolism, demonstrating the distinctive catabolic role of this receptor compared with PPARγ. PMID:19968882

  15. MUG-OBS - Multiparameter Geophysical Ocean Bottom System : a new instrumental approach to monitor earthquakes.

    NASA Astrophysics Data System (ADS)

    hello, yann; Charvis, Philippe; Yegikyan, Manuk; verfaillie, Romain; Rivet, Diane

    2016-04-01

    Real time monitoring of seismic activity is a major issue for early warning of earthquakes and tsunamis. It can be done using regional scale wired nodes, such as Neptune in Canada and in the U.S, or DONET in Japan. Another approach to monitor seismic activity at sea is to deploying repeatedly OBS array like during the amphibious Cascadia Initiative (four time 1-year deployments), the Japanese Pacific Array (broadband OBSs "ocean-bottom broadband dispersion survey" with 2-years autonomy), the Obsismer program in the French Lesser Antilles (eight time 6-months deployments) and the Osisec program in Ecuador (four time 6-months deployments). These autonomous OBSs are self-recovered or recovered using an ROV. These systems are costly including ship time, and require to recover the OBS before to start working on data. Among the most recent alternative we developed a 3/4 years autonomy ocean bottom system with 9 channels (?) allowing the acquisition of different seismic or environmental parameters. MUG-OBS is a free falling instrument rated down to 6000 m. The installation of the sensor is monitored by acoustic commands from the surface and a health bulletin with data checking is recovered by acoustic during the installation. The major innovation is that it is possible to recover the data any time on demand (regularly every 6-months or after a crisis) using one of the 6 data-shuttles released from the surface by acoustic command using a one day fast cruise boat of opportunity. Since sensors stayed at the same location for 3 years, it is a perfect tool to monitor large seismic events, background seismic activity and aftershock distribution. Clock, drift measurement and GPS localization is automatic when the shuttle reaches the surface. For remote areas, shuttles released automatically and a seismic events bulletin is transmitted. Selected data can be recovered by two-way Iridium satellite communication. After a period of 3 years the main station is self-recovered by

  16. ObsPy: A Python toolbox for seismology - Current state, applications, and ecosystem around it

    NASA Astrophysics Data System (ADS)

    Krischer, L.; Megies, T.; Sales de Andrade, E.; Barsch, R.; Beyreuther, M.

    2015-12-01

    ObsPy (http://www.obspy.org) is a community-driven, open-source project offering a bridge for seismology into the scientific Python ecosystem. It provides read and write support for essentially all commonly used waveform, station, and event metadata formats with a unified interface, a comprehensive signal processing toolbox tuned to the needs of seismologists, integrated access to all large data centers, web services and databases, and convenient wrappers to third party codes like libmseed and evalresp. Python, in contrast to many other languages and tools, is simple enough to enable an exploratory and interactive coding style desired by many scientists. At the same time it is a full-fledged programming language usable by software engineers to build complex and large programs. This combination makes it very suitable for use in seismology where research code often has to be translated to stable and production ready environments. It furthermore offers many freely available high quality scientific modules covering most needs in developing scientific software.ObsPy has been in constant development for more than 5 years and nowadays enjoys a large rate of adoption in the community with thousands of users. Successful applications include time-dependent and rotational seismology, big data processing, event relocations, and synthetic studies about attenuation kernels and full-waveform inversions to name a few examples. Additionally it sparked the development of several more specialized packages slowly building a modern seismological ecosystem around it.This contribution will give a short introduction and overview of ObsPy and highlight a number of us cases and software built around it. We will furthermore discuss the issue of sustainability of scientific software.

  17. Interstellar Environments and Dust Properties toward Cygnus OB2 No. 12: A Reassessment

    NASA Astrophysics Data System (ADS)

    Whittet, D. C. B.

    2015-10-01

    The B-type hypergiant Cygnus OB2 no. 12 is a popular target for studies of interstellar phenomena at visible-infrared wavelengths because of its exceptional brightness for a star dimmed by some 10 mag of visual extinction. A lack of detectable ice absorption has led investigators to regard the line of sight as a standard for studies of the “diffuse” interstellar medium (ISM), an assumption challenged both by observations of molecular gas toward the star and by uncertainties concerning the degree to which such a luminous object may affect its local environment. This paper presents a reassessment of the nature of the material responsible for extinction toward Cyg OB2 no. 12. The excess relative to other cluster members appears to occur in translucent clumps within an extensive network of clouds in the region. Attenuation of the ambient radiation field is sufficient in the cores of the clumps to support the presence of gas-phase molecules, but not to sustain detectable ice formation. In general, the optical properties of dust in the clumps are closely similar to those observed in typical diffuse interstellar material, with the notable exception of an unusually low value for the wavelength of maximum polarization. The implied enhancement of polarization by small grains is attributed to increased alignment efficiency in an enhanced magnetic field. This caveat apart, the results of the current paper provide reassurance that Cyg OB2 no. 12 is, indeed, an appropriate choice for studies that target diffuse and translucent phases of the ISM.

  18. SPITZER IMAGING OF THE NEARBY RICH YOUNG CLUSTER, Cep OB3b

    SciTech Connect

    Allen, Thomas S.; Kryukova, Erin; Thomas Megeath, S.; Gutermuth, Robert A.; Pipher, Judith L.; Naylor, Tim; Jeffries, R. D.; Wolk, Scott J.; Spitzbart, Brad; Muzerolle, James

    2012-05-10

    We map the full extent of a rich massive young cluster in the Cep OB3b association with the Infrared Array Camera and Multi-band Imaging Photometer System instruments aboard the Spitzer Space Telescope and the ACIS instrument aboard the Chandra X-Ray Observatory. At 700 pc, it is revealed to be the second nearest large (>1000 member), young (<5 Myr) cluster known. In contrast to the nearest large cluster, the Orion Nebula Cluster, Cep OB3b is only lightly obscured and is mostly located in a large cavity carved out of the surrounding molecular cloud. Our infrared and X-ray data sets, as well as visible photometry from the literature, are used to take a census of the young stars in Cep OB3b. We find that the young stars within the cluster are concentrated in two sub-clusters; an eastern sub-cluster, near the Cep B molecular clump, and a western sub-cluster, near the Cep F molecular clump. Using our census of young stars, we examine the fraction of young stars with infrared excesses indicative of circumstellar disks. We create a map of the disk fraction throughout the cluster and find that it is spatially variable. Due to these spatial variations, the two sub-clusters exhibit substantially different average disk fractions from each other: 32% {+-} 4% and 50% {+-} 6%. We discuss whether the discrepant disk fractions are due to the photodestruction of disks by the high mass members of the cluster or whether they result from differences in the ages of the sub-clusters. We conclude that the discrepant disk fractions are most likely due to differences in the ages.

  19. OB ASSOCIATIONS AT THE UPPER END OF THE MILKY WAY LUMINOSITY FUNCTION

    SciTech Connect

    Rahman, Mubdi; Matzner, Christopher D.; Moon, Dae-Sik

    2013-04-01

    The Milky Way's most luminous, young, and massive (M {approx}> 10{sup 4} M{sub Sun }) star clusters and OB associations have largely evaded detection despite knowledge of their surrounding H II regions. We search for these clusters and associations within the 40 star-forming complexes from Rahman and Murray in the 13 most luminous Wilkinson Microwave Anisotropy Probe (WMAP) free-free emission sources of the Galaxy. Selecting for objects with the dust-reddened colors of OB stars, we identify new candidate associations using the Two Micron All Sky Survey point-source catalog. In 40 star-forming complexes searched, 22 contain cluster/association candidates with sizes and masses in the range of 3'-26' and 10{sup 2.3}-10{sup 5} M{sub Sun }. Of the 22 candidates, at least seven have estimated masses {approx}> 10{sup 4} M{sub Sun }, doubling the number of such massive clusters known in the Galaxy. Only one of the searched WMAP sources remains without a candidate. Applying our method to a statistically similar set of test locations, we estimate that 3.0 {+-} 0.6 of our 22 candidate associations are unrelated to the star-forming complexes. In addition, the apparent extinctions of our candidate associations correlate well with the predictions from a Galactic model. These facts, along with the clear detection of a known OB association and the previous spectral verification of one cluster found by this method, validate our method. In eight of the most luminous WMAP sources, the candidate associations can account for the observed free-free flux. With our new compilation, the Galactic census of young, massive stellar associations may now be about half complete.

  20. Nature vs. Nurture: The influence of OB star environments on proto-planetary disk evolution.

    NASA Astrophysics Data System (ADS)

    Bouwman, Jeroen; Feigelson, Eric; Getman, Kostantin; Henning, Thomas; Lawson, Warrick; Linz, Hendrik; Luhman, Kevin; Roccatagliata, Veronica; Sicilia Aguilar, Aurora; Townsley, Leisa; Wang, Junfeng

    2006-05-01

    A natural approach for understanding the origin and diversity of planetary systems is to study the birth sites of planetary systems under varying environmental conditions. Dust grains in protoplanetary disks, the building blocks of planets, are structurally and chemically altered, and grow through coagulation into planetesimals. The disk geometry may change from a flaring to a more flattened structure, gaps may develop under the gravitational influence of protoplanets, and eventually the disk will dissipate, terminating the planet formation process. While the infrared properties of disks in quiet cloud environments have been extensively studied, investigations under the conditions of strong UV radiation and stellar winds in the proximity of OB stars have been limited. We propose a combined IRAC/IRS study of a large, well-defined and unbiased X-ray selected sample of pre-main-sequence stars in three OB associations: Pismis 24 in NGC 6357, NGC 2244 in the Rosette Nebula, and IC 1795 in the W3 complex. The samples are based on recent Chandra X-ray Observatory studies which reliably identify hundreds of cluster members and were carefully chosen to avoid high infrared nebular background. A new Chandra exposure of IC 1795 is requested, and an optical followup to characterise the host stars is planned. Modelling the Spitzer findings will provide the composition and size of dust present as well as the geometry, mass, and gaps in the global structure of the disk. As hundreds of cluster members will be covered with IRAC and dozens with IRS, good statistics on the disk evolution and dispersal as a function of location with respect to OB stars will be obtained. Comparison of disk properties within our sample and with existing Spitzer studies of quiescent star-forming regions should significantly advance the aim of characterising the influence of the environment on the evolution of protoplanetary disks. This effort relies on a powerful synergy between the Chandra and Spitzer

  1. ObsPy: A Python toolbox for seismology - Current state, applications, and ecosystem around it

    NASA Astrophysics Data System (ADS)

    Lecocq, Thomas; Megies, Tobias; Krischer, Lion; Sales de Andrade, Elliott; Barsch, Robert; Beyreuther, Moritz

    2016-04-01

    ObsPy (http://www.obspy.org) is a community-driven, open-source project offering a bridge for seismology into the scientific Python ecosystem. It provides * read and write support for essentially all commonly used waveform, station, and event metadata formats with a unified interface, * a comprehensive signal processing toolbox tuned to the needs of seismologists, * integrated access to all large data centers, web services and databases, and * convenient wrappers to third party codes like libmseed and evalresp. Python, in contrast to many other languages and tools, is simple enough to enable an exploratory and interactive coding style desired by many scientists. At the same time it is a full-fledged programming language usable by software engineers to build complex and large programs. This combination makes it very suitable for use in seismology where research code often has to be translated to stable and production ready environments. It furthermore offers many freely available high quality scientific modules covering most needs in developing scientific software. ObsPy has been in constant development for more than 5 years and nowadays enjoys a large rate of adoption in the community with thousands of users. Successful applications include time-dependent and rotational seismology, big data processing, event relocations, and synthetic studies about attenuation kernels and full-waveform inversions to name a few examples. Additionally it sparked the development of several more specialized packages slowly building a modern seismological ecosystem around it. This contribution will give a short introduction and overview of ObsPy and highlight a number of use cases and software built around it. We will furthermore discuss the issue of sustainability of scientific software.

  2. INTERSTELLAR ENVIRONMENTS AND DUST PROPERTIES TOWARD CYGNUS OB2 NO. 12: A REASSESSMENT

    SciTech Connect

    Whittet, D. C. B.

    2015-10-01

    The B-type hypergiant Cygnus OB2 no. 12 is a popular target for studies of interstellar phenomena at visible-infrared wavelengths because of its exceptional brightness for a star dimmed by some 10 mag of visual extinction. A lack of detectable ice absorption has led investigators to regard the line of sight as a standard for studies of the “diffuse” interstellar medium (ISM), an assumption challenged both by observations of molecular gas toward the star and by uncertainties concerning the degree to which such a luminous object may affect its local environment. This paper presents a reassessment of the nature of the material responsible for extinction toward Cyg OB2 no. 12. The excess relative to other cluster members appears to occur in translucent clumps within an extensive network of clouds in the region. Attenuation of the ambient radiation field is sufficient in the cores of the clumps to support the presence of gas-phase molecules, but not to sustain detectable ice formation. In general, the optical properties of dust in the clumps are closely similar to those observed in typical diffuse interstellar material, with the notable exception of an unusually low value for the wavelength of maximum polarization. The implied enhancement of polarization by small grains is attributed to increased alignment efficiency in an enhanced magnetic field. This caveat apart, the results of the current paper provide reassurance that Cyg OB2 no. 12 is, indeed, an appropriate choice for studies that target diffuse and translucent phases of the ISM.

  3. A Multi-Fiber Spectroscopic Search for Low-mass Young Stars in Orion OB1

    NASA Astrophysics Data System (ADS)

    Loerincs, Jacqueline; Briceno, Cesar; Calvet, Nuria; Mateo, Mario L.; Hernandez, Jesus

    2017-01-01

    We present here results of a low resolution spectroscopic followup of candidate low-mass pre-main sequence stars in the Orion OB1 association. Our targets were selected from the CIDA Variability Survey of Orion (CVSO), and we used the Michigan/Magellan Fiber Spectrograph (M2FS) on the Magellan Clay 6.5m telescope to obtain spectra of 500 candidate T Tauri stars distributed in seven 0.5 deg diameter fields, adding to a total area of ~5.5 deg2. We identify young stars by looking at the distinctive Hα 6563 Å emission and Lithium Li I 6707 Å absorption features characteristic of young low mass pre-main sequence stars. Furthermore, by measuring the strength of their Hα emission lines, confirmed T Tauri stars can be classified as either Classical T Tauris (CTTS) or Weak-line T Tauris (WTTS), which give indication of whether the star is actively accreting material from a gas and dust disk surrounding the star, which may be the precursor of a planetary system. We confirm a total of 90 T Tauri stars, of which 50% are newly identified young members of Orion; out of the 49 new detections,15 are accreting CTTS, and of these all but one are found in the OB1b sub-region. This result is in line with our previous findings that this region is much younger than the more extended Orion OB1a sub-association. The M2FS results add to our growing census of young stars in Orion, that is allowing us to characterize in a systematic and consistent way the distribution of stellar ages across the entire complex, in order to building a complete picture of star formation in this, one of nearest most active sites of star birth.

  4. Winds of low-metallicity OB-type stars: HST-COS spectroscopy in IC 1613

    SciTech Connect

    Garcia, Miriam; Najarro, Francisco; Herrero, Artemio; Urbaneja, Miguel Alejandro

    2014-06-10

    We present the first quantitative ultraviolet spectroscopic analysis of resolved OB stars in IC 1613. Because of its alleged very low metallicity (≲1/10 Z {sub ☉}, from H II regions), studies in this Local Group dwarf galaxy could become a significant step forward from the Small Magellanic Cloud (SMC) toward the extremely metal-poor massive stars of the early universe. We present HST-COS data covering the ∼1150-1800 Å wavelength range with resolution R ∼ 2500. We find that the targets do exhibit wind features, and these are similar in strength to SMC stars. Wind terminal velocities were derived from the observed P Cygni profiles with the Sobolev plus Exact Integration method. The v {sub ∞}-Z relationship has been revisited. The terminal velocity of IC 1613 O stars is clearly lower than Milky Way counterparts, but there is no clear difference between IC 1613 and SMC or LMC analog stars. We find no clear segregation with host galaxy in the terminal velocities of B-supergiants, nor in the v {sub ∞}/v {sub esc} ratio of the whole OB star sample in any of the studied galaxies. Finally, we present the first evidence that the Fe-abundance of IC 1613 OB stars is similar to the SMC, which is in agreement with previous results on red supergiants. With the confirmed ∼1/10 solar oxygen abundances of B-supergiants, our results indicate that IC 1613's α/Fe ratio is sub-solar.

  5. A Spitzer view of the giant molecular cloud Mon OB1 East/NGC 2264

    SciTech Connect

    Rapson, V. A.; Pipher, J. L.; Gutermuth, R. A.; Megeath, S. T.; Allen, T. S.; Myers, P. C.; Allen, L. E.

    2014-10-20

    We present Spitzer 3.6, 4.5, 5.8, 8.0, and 24 μm images of the Mon OB1 East giant molecular cloud, which contains the young star forming region NGC 2264, as well as more extended star formation. With Spitzer data and Two Micron All Sky Survey photometry, we identify and classify young stellar objects (YSOs) with dusty circumstellar disks and/or envelopes in Mon OB1 East by their infrared-excess emission and study their distribution with respect to cloud material. We find a correlation between the local surface density of YSOs and column density of molecular gas as traced by dust extinction that is roughly described as a power law in these quantities. NGC 2264 follows a power-law index of ∼2.7, exhibiting a large YSO surface density for a given gas column density. Outside of NGC 2264 where the surface density of YSOs is lower, the power law is shallower and the region exhibits a larger gas column density for a YSO surface density, suggesting the star formation is more recent. In order to measure the fraction of cloud members with circumstellar disks/envelopes, we estimate the number of diskless pre-main-sequence stars by statistical removal of background star detections. We find that the disk fraction of the NGC 2264 region is 45%, while the surrounding, more distributed regions show a disk fraction of 19%. This may be explained by the presence of an older, more dispersed population of stars. In total, the Spitzer observations provide evidence for heterogenous, non-coeval star formation throughout the Mon OB1 cloud.

  6. Luminosity functions and color-magnitude diagrams for three OB associations in the Large Magellanic Cloud

    NASA Technical Reports Server (NTRS)

    Degioia-Eastwood, K.; Meyers, R. P.; Jones, D. P.

    1993-01-01

    Using the point spread function photometry program DAOPHOT, we have used UBV CCD photometry to construct color-magnitude diagrams and luminosity functions for three OB associations in the Large Magellanic Cloud. The region LH 76 appears to be completely coeval; the region LH 13 shows some evidence for noncoevality which will need to be checked with spectra of the stars in question. The region LH 105, which lies on the southern edge of 30 Doradus, shows significant contamination by an underlying older population, possibly from previous star forming events. The luminosity functions, which serve as the first step toward determining the initial mass function in these regions, are calculated.

  7. Nature vs. Nurture: The influence of OB star environments on proto-planetary disk evolution

    NASA Astrophysics Data System (ADS)

    Bouwman, Jeroen

    2006-09-01

    We propose a combined IRAC/IRS study of a large, well-defined and unbiased X-ray selected sample of pre-main-sequence stars in three OB associations: Pismis 24 in NGC 6357, NGC 2244 in the Rosette Nebula, and IC 1795 in the W3 complex. The samples are based on recent Chandra X-ray Observatory studies which reliably identify hundreds of cluster members and were carefully chosen to avoid high infrared nebular background. A new Chandra exposure of IC 1795 is requested, and an optical followup to characterise the host stars is planned.

  8. Synthetic filter photometry and evolutionary status of two Be stars in the association Per OB1

    NASA Technical Reports Server (NTRS)

    Torres, Ana V.

    1987-01-01

    Stromgren and H-beta colors have been determined from spectrophotometric observations for two Be stars without published photometry in the association Per OB1: HD 12856 (B0 pe) and HD 13890 (B1 III:pe). Stellar parameters and improved spectral types are then derived from the color indices using the calibrations of Jakobsen (1986), and independently from the BCD classification method. The intrinsic properties of HD 12856 and HD 13890 are compared with those of normal B stars and are used to estimate their evolutionary status.

  9. BOREAS TF-8 NSA-OJP and SSA-OBS Ceilometer Data

    NASA Technical Reports Server (NTRS)

    Moore, Kathleen E.; Hall, Forrest G. (Editor); Huemmrich, Karl (Editor); Fitzjarrald, David R.

    2000-01-01

    The BOREAS TF-8 team used ceilometers to collect data on the fraction of the sky covered with clouds and the cloud height. Included with these data is the surface-based lifting condensation level, derived from temperature and humidity values acquired at the flux tower at the NSA-OJP site. Ceilo-meter data were collected at the NSA-OJP site in 1994 and at the NSA-OJP and SSA-OBS sites in 1996. The data are available in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884).

  10. Detection of H3+ in the diffuse interstellar medium toward Cygnus OB2 No. 12.

    PubMed

    McCall, B J; Geballe, T R; Hinkle, K H; Oka, T

    1998-03-20

    The molecular ion H3+ is considered the cornerstone of interstellar chemistry because it initiates the reactions responsible for the production of many larger molecules. Recently discovered in dense molecular clouds, H3+ has now been observed in the diffuse interstellar medium toward Cygnus OB2 No. 12. Analysis of H3+ chemistry suggests that the high H3+ column density (3.8 x 10(14) per square centimeter) is due not to a high H3+ concentration but to a long absorption path. This and other work demonstrate the ubiquity of H3+ and its potential as a probe of the physical and chemical conditions in the interstellar medium.

  11. The OB-fold domain 1 of human POT1 recognizes both telomeric and non-telomeric DNA motifs

    PubMed Central

    Kolar, Carol; Yan, Ying; Borgstahl, Gloria E.O.; Ouellette, Michel M.

    2015-01-01

    The POT1 protein plays a critical role in telomere protection and telomerase regulation. POT1 binds single-stranded 5’-TTAGGGTTAG-3’ and forms a dimer with the TPP1 protein. The dimer is recruited to telomeres, either directly or as part of the Shelterin complex. Human POT1 contains two Oligonucleotide/Oligosaccharide Binding (OB) fold domains, OB1 and OB2, which make physical contact with the DNA. OB1 recognizes 5’-TTAGGG whereas OB2 binds to the downstream TTAG-3’. Studies of POT1 proteins from other species have shown that some of these proteins are able to recognize a broader variety of DNA ligands than expected. To explore this possibility in humans, we have used SELEX to reexamine the sequence-specificity of the protein. Using human POT1 as a selection matrix, high-affinity DNA ligands were selected from a pool of randomized single-stranded oligonucleotides. After six successive rounds of selection, two classes of high-affinity targets were obtained. The first class was composed of oligonucleotides containing a cognate POT1 binding sites (5’-TTAGGGTTAG-3’). The second and more abundant class was made of molecules that carried a novel non-telomeric consensus: 5’-TNCANNAGKKKTTAGG-3’ (where K=G/T and N=any base). Binding studies showed that these non-telomeric sites were made of an OB1-binding motif (TTAGG) and a non-telomeric motif (NT motif), with the two motifs recognized by distinct regions of the OB1 domain. POT1 interacted with these non-telomeric binding sites with high affinity and specificity, even when bound to its dimerization partner TPP1. This intrinsic ability of POT1 to recognize NT motifs raises the possibility that the protein may fulfill additional functions at certain non-telomeric locations of the genome, in perhaps gene transcription, replication, or repair. PMID:25934589

  12. Ocean Basalt Simulator version 1 (OBS1): Trace element mass balance in adiabatic melting of a pyroxenite-bearing peridotite

    NASA Astrophysics Data System (ADS)

    Kimura, J. I.; Kawabata, H.

    2014-12-01

    We present a new numerical mass balance model for estimating the source conditions of a primary ocean basalt from adiabatic melting of a pyroxenite-bearing peridotite. The Ocean Basalt Simulator version 1 (OBS1) uses a thermodynamic model of adiabatic melting of a pyroxenite-bearing peridotite with experimentally parameterized liquidus-solidus and melting intervals and thermodynamically/experimentally parameterized source mineralogy of pyroxenite and peridotite. OBS1 uses a sequence of adiabatic melting with pyroxenite melting, melt metasomatism in the host peridotite, and melting of the metasomatized peridotite. OBS1 explores (1) the fractions of peridotite and pyroxenite, (2) mantle potential temperature Tp, (3) depth of termination of melting Pmt, (4) degree of melting F, and (5) residual mode Xa of the sources. The model also examines the mass balance of 26 incompatible trace elements in the sources and in the generated basalt. OBS1 can also calculate Sr-Nd-Hf-Pb isotope compositions in the sources and in the melt. OBS1 is coded in an Excel spreadsheet and runs with VBA macros. Using OBS1, we examine the source conditions of the mid oceanic ridge basalts (MORBs), plume-influenced ocean ridge basalts in Galápagos, Loihi-Loa-Koolau basalts in the Hawaiian hotspot, high-mu (HIMU) basalt from the St. Helena hotspot, and Shatsky Rise and Jurassic Mikabu oceanic plateau basalts and picrites. OBS1 is a unique model that provides an opportunity to examine the source mantle conditions using incompatible trace elements and relevant isotopes, which are key factors in global mantle recycling.

  13. Analysis of interstellar extinction towards the hypergiant Cyg OB2 No. 12

    NASA Astrophysics Data System (ADS)

    Maryeva, O. V.; Chentsov, E. L.; Goranskij, V. P.; Karpov, S. V.

    The Cyg OB2 stellar association hosts an entire zoo of unique objects, and among them -- an enigmatic star Cyg OB2 No. 12 (Schulte 12, MT 304). MT 304 is enigmatic not only due to its highest luminosity (according to various estimates, it is one of the brightest stars in the Galaxy), but also because its reddening is anomalously large, greater than the mean reddening in the association. To explain the nature of anomalous reddening (AV≃ 10 mag) of MT 304, we carried out spectrophotometric observations of 25 stars located in its vicinity. We mapped interstellar extinction within the 2.5 arcmin radius and found it to increase towards MT 304. According to our results, the two most reddened stars in the association after MT 304 are J203240.35+411420.1 and J203239.90+411436.2, both located about 15 arcsec from it. Interstellar extinction AV towards these stars is about 9 mag. Our results favor the hypothesis of the circumstellar nature of reddening excess. In the second part of the paper we present the results of our modeling of MT 282 (B1 IV) and MT 343 (B1 V), which belong to the older population of the association and have ages greater than 10 Myr.

  14. Parametrization of DFTB3/3OB for Magnesium and Zinc for Chemical and Biological Applications

    PubMed Central

    2015-01-01

    We report the parametrization of the approximate density functional theory, DFTB3, for magnesium and zinc for chemical and biological applications. The parametrization strategy follows that established in previous work that parametrized several key main group elements (O, N, C, H, P, and S). This 3OB set of parameters can thus be used to study many chemical and biochemical systems. The parameters are benchmarked using both gas-phase and condensed-phase systems. The gas-phase results are compared to DFT (mostly B3LYP), ab initio (MP2 and G3B3), and PM6, as well as to a previous DFTB parametrization (MIO). The results indicate that DFTB3/3OB is particularly successful at predicting structures, including rather complex dinuclear metalloenzyme active sites, while being semiquantitative (with a typical mean absolute deviation (MAD) of ∼3–5 kcal/mol) for energetics. Single-point calculations with high-level quantum mechanics (QM) methods generally lead to very satisfying (a typical MAD of ∼1 kcal/mol) energetic properties. DFTB3/MM simulations for solution and two enzyme systems also lead to encouraging structural and energetic properties in comparison to available experimental data. The remaining limitations of DFTB3, such as the treatment of interaction between metal ions and highly charged/polarizable ligands, are also discussed. PMID:25178644

  15. La binaria LSS 3074 y su entorno: ?`una nueva asociación OB?

    NASA Astrophysics Data System (ADS)

    Niemela, V.; Morrell, N.; Corti, M.

    En este trabajo presentamos un nuevo análisis orbital de LSS~3074, junto con tipos espectrales y velocidades radiales de estrellas que podrían constituir con ella una nueva asociación OB. La estrella O4f LSS3074 fue descubierta como binaria espectroscópica de corto período y líneas dobles por Morrell & Niemela (1990, ASP Conf. Ser. 7, 57). Posteriormente, Haefner et~al.(1994, IBVS 3969) encontraron variaciones fotométricas, estimando una inclinación orbital entre 50o y 55o. Teniendo en cuenta la importancia de obtener valores empíricos para las masas de estrellas O tempranas, y considerando la gran dispersión existente entre los valores observados y su discrepancia con los predichos por los modelos teóricos, hemos obtenido nuevas observaciones espectroscópicas de este sistema, con el propósito de mejorar los elementos orbitales derivados en la solución preliminar. Además, como las estrellas O tempranas suelen formar parte de cúmulos y asociaciones OB, hemos llevado a cabo una investigación espectroscópica de varias estrellas tempranas que podrían estar físicamente relacionadas con LSS~3074.

  16. BOREAS TGB-8 Monoterpene Concentration Data over the SSA-OBS

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Conrad, Sara K. (Editor); Lerdau, Manuel

    2000-01-01

    The BOREAS TGB-8 team collected data to investigate the controls over NMHC fluxes from boreal forest tree species. This data set contains measurements of monoterpene concentrations in collected foliar gas emissions and foliar samples. The data were collected at the OJP and OBS tower flux sites in the SSA and were the locus for the monoterpene emission measurements. These areas contained mature stands of jack pine and black spruce and were the focal sites in the BOREAS program for studies of biosphere/atmosphere exchange from these two habitat types. The OBS site is situated in a black spruce/sphagnum bog with the largest trees 155 years old and 10-15 m tall. The OJP site is in a jack pine forest, 80 to 120 years old, which lies on a sandy bench of glacial outwash with the largest tree standing 15 m tall. Temporally, the data cover the period of 24-May-1994 to 19-Sep-1994. The data are stored in tabular ASCII files.

  17. Hard X-ray Flux from Low-Mass Stars in the Cygnus OB2 Association

    NASA Astrophysics Data System (ADS)

    Caramazza, M.; Drake, J. J.; Micela, G.; Flaccomio, E.

    2009-05-01

    We investigate the X-ray emission in the 20-40 keV band expected from the flaring low-mass stellar population in Cygnus OB2 assuming that the observed soft X-ray emission is due to a superposition of flares and that the ratio of hard X-ray to soft X-ray emission is described by a scaling found for solar flares by Isola and co-workers. We estimate a low-mass stellar hard X-ray flux in the 20-40 keV band in the range ~7×1031-7×1033 erg/s and speculate the limit of this values. Hard X-ray emission could lie at a level not much below the current observed flux upper limits for Cygnus OB2. Simbol-X, with its broad energy band (10-100 keV) and its sensitivity should be able to detect this emission and would provide insights into the hard X-ray production of flares on pre-main sequence stars.

  18. Stellar Parameters of A- and B-type Members of the Scorpius-Centaurus OB Association

    NASA Astrophysics Data System (ADS)

    Eckelkamp, Grant; Smith, Skylar; Pecaut, Mark; Mamajek, Eric E.

    2017-01-01

    Advances in high-contrast imaging and radio interferometry are allowing new avenues for circumstellar disk studies as well as direct imaging exoplanet searches. The most promising targets in these studies are intermediate mass B/A/F type members of the Scorpius-Centaurus OB association at a distance of ~100-200 pc and an age of 10-20 Myr old. However, many of the most interesting stellar members of Sco-Cen have poorly constrained stellar properties, including luminosities, distances and masses. In order to address this, we have obtained low resolution spectra from the SMARTS 1.5 m telescope and have obtained new spectral classifications for 106 stars. Using these new spectral classifications along with visual and near-infrared photometry from GAIA, Hipparcos, Tycho2, APASS and 2MASS, we obtained new reddening and extinction estimates. We then placed the stars on a Hertzsprung-Russell diagram and compared with stellar evolutionary tracks to obtain individual masses and ages. These improved stellar parameters will provide essential data for improving our understanding of high contrast imaging targets of B/A/F type members within the nearest OB association. We acknowledge support from NSF awards AST-1008908 and AST-1313029.

  19. THE ORIGIN OF OB CLUSTERS: FROM 10 pc TO 0.1 pc

    SciTech Connect

    Liu Hauyu Baobab; Wang Ke; Ho, Paul T. P.; Zhang Qizhou; Quintana-Lacaci, Guillermo; Li Zhiyun; Zhang Zhiyu E-mail: kwang@cfa.harvard.edu E-mail: quintana@iram.es E-mail: zl4h@virginia.edu

    2012-01-20

    We observe the 1.2 mm continuum emission around the OB cluster-forming region G10.6-0.4, using the MAMBO-2 bolometer array of the IRAM 30 m telescope and the Submillimeter Array (SMA). Comparison of the Spitzer 24 {mu}m and 8 {mu}m images with our 1.2 mm continuum maps reveal an ionization front of an H II region, the photon-dominated layer, and several 5 pc scale filaments that follow the outer edge of the photon-dominated layer. The filaments, which are resolved in the MAMBO-2 observations, show regularly spaced parsec-scale molecular clumps, embedded with a cluster of dense molecular cores as shown in the SMA 0.87 mm observations. Toward the center of the G10.6-0.4 region, the combined SMA+IRAM 30 m continuum image reveals several parsec-scale protrusions. They may continue down to within 0.1 pc of the geometric center of a dense 3 pc scale structure, where a 200 M{sub Sun} OB cluster resides. The observed filaments may facilitate mass accretion onto the central cluster-forming region in the presence of strong radiative and mechanical stellar feedback. Their filamentary geometry may also facilitate fragmentation. We did not detect any significant polarized emission at 0.87 mm in the inner 1 pc region with SMA.

  20. A model for the infrared emission from an OB star cluster environment

    NASA Technical Reports Server (NTRS)

    Leisawitz, D.

    1991-01-01

    A model for the infrared emission from the neighborhood of an OB star cluster is described. The distribution of gas and dust around the stars, properties of the dust, and the cluster and interstellar radiation fields are variable. The model can be applied to regions around clusters embedded to various degrees in their parental molecular clouds (i.e., compact H II regions, blister-type H II regions, and the tenuous H II regions ionized by naked O stars). The model is used to simulate IRAS observations of a typical blister H II region. Infrared surface brightness and spectral energy distributions are predicted and the impact of limited spatial resolution is illustrated. The model results are shown to be consistent with observations of the exemplary outer Galaxy OB cluster NGC 7380. It is planned to use the model as a diagnostic tool to probe the physical conditions and dust properties in star-formation regions and, ultimately, in an interpretation of the spectral energy distributions of spiral galaxies.

  1. ObsPy: a bridge for seismology into the scientific Python ecosystem

    NASA Astrophysics Data System (ADS)

    Krischer, Lion; Megies, Tobias; Barsch, Robert; Beyreuther, Moritz; Lecocq, Thomas; Caudron, Corentin; Wassermann, Joachim

    2015-01-01

    The Python libraries NumPy and SciPy are extremely powerful tools for numerical processing and analysis well suited to a large variety of applications. We developed ObsPy (http://obspy.org), a Python library for seismology intended to facilitate the development of seismological software packages and workflows, to utilize these abilities and provide a bridge for seismology into the larger scientific Python ecosystem. Scientists in many domains who wish to convert their existing tools and applications to take advantage of a platform like the one Python provides are confronted with several hurdles such as special file formats, unknown terminology, and no suitable replacement for a non-trivial piece of software. We present an approach to implement a domain-specific time series library on top of the scientific NumPy stack. In so doing, we show a realization of an abstract internal representation of time series data permitting I/O support for a diverse collection of file formats. Then we detail the integration and repurposing of well established legacy codes, enabling them to be used in modern workflows composed in Python. Finally we present a case study on how to integrate research code into ObsPy, opening it to the broader community. While the implementations presented in this work are specific to seismology, many of the described concepts and abstractions are directly applicable to other sciences, especially to those with an emphasis on time series analysis.

  2. BOREAS TGB-8 Starch Concentration Data Over the SSA-OBS and the SSA-OJP

    NASA Technical Reports Server (NTRS)

    Lerdau, Manuel; Hall, Forrest G. (Editor); Conrad, Sara K. (Editor)

    2000-01-01

    The BOREAS TGB-8 team collected data to investigate the controls over NMHC fluxes from boreal forest tree species. This data set includes measurements of starch concentrations in foliar samples at mature jack pine and black spruce sites. The data were collected at the OJP and OBS tower flux locations in the BOREAS SSA. These areas contained mature stands of jack pine and black spruce and were the focal sites in the BOREAS program for studies of biosphere/atmosphere exchange from these two habitat types. The OBS site is situated in a black spruce/sphagnum bog with the largest trees 155 years old and 10-15 m tall. The OJP site is in a jack pine forest, 80 to 120 years old, which lies on a sandy bench of glacial outwash with the largest tree standing 15 m tall. Temporally, the data cover the period of 24-May-1994 to 19-Sep-1994. The data are stored in tabular ASCII files.

  3. Phenotypic characterization of copper-resistant mutants of Methylosinus trichosporium OB3b.

    PubMed Central

    Fitch, M W; Graham, D W; Arnold, R G; Agarwal, S K; Phelps, P; Speitel, G E; Georgiou, G

    1993-01-01

    Cultures of Methylosinus trichosporium OB3b grown in the presence of very low concentrations of copper synthesize a soluble methane monooxygenase (sMMO) that efficiently catalyzes the oxidation of trichloroethylene and other organic pollutants. Recently, we isolated five M. trichosporium OB3b mutants that express sMMO activity when grown in the presence of elevated copper concentrations (P.A. Phelps, S. K. Agarwal, G. E. Speitel, Jr., and G. Georgiou, Appl. Environ. Microbiol. 58:3701-3708, 1992). Here we show that, in contrast to the results for the wild-type cells, the addition of copper to mutant cultures grown on methane and nitrate as the nitrogen source has no noticeable effect on the growth rate and sMMO expression. In vitro experiments indicated that the copper-resistant phenotype does not arise from an increased stability of sMMO to copper deactivation. Furthermore, the mutant cultures exhibit altered speciation of copper in the extracellular fluid and have substantially decreased levels of cell-associated copper. On the basis of these results, we propose that the mutant phenotype arises from defects in copper uptake and metabolism rather than from changes in sMMO expression or enzyme stability. Images PMID:8215352

  4. Analysis of the kinematic structure of the Cygnus OB1 association

    NASA Astrophysics Data System (ADS)

    Costado, M. T.; Alfaro, E. J.; González, M.; Sampedro, L.

    2017-03-01

    The main objective of this study is the characterization of the velocity field in the Cygnus OB1 association using the radial velocity data currently available in the literature. This association is part of a larger star-forming complex located in the direction of the Cygnus region, but whose main subsystems may be distributed at different distances from the sun. We have collected radial velocity data for more than 300 stars in the area of 5 × 5 deg2 centred on the Cygnus OB1 association. We present the results of a kinematic clustering analysis in the subspace of the phase space formed by angular coordinates and radial velocity using two independent methodologies. We have found evidence of structure in the phase space with the detection of two main groups, corresponding to different radial velocity and distance values, belonging to the association, and associated with two main shells defined by the Hα emission. A third grouping well separated from the other two in velocity appears to occupy the whole region associated with what has been called 'common shell'.

  5. Interstellar NaI absorption towards the stellar association ARA OB1

    NASA Astrophysics Data System (ADS)

    Whiteoak, J. B.; Gardner, F. F.

    Observations have been made of the interstellar D-line absorption of Na I towards a loose grouping of OB stars (containing the association Ara OB1 and probably the H-alpha emission regions RCW 107 and 108) centered at 1 = 337.5 deg and b = - 0.5 deg. The individual absorption spectra contain several velocity components which show well-defined groupings at - 37, -18 and 0 km/s. The corresponding median optical depths are 2, 7 and 6. The evidence indicates that both the -37 and -18 km/s Na I clouds are located in the Carina-Sagittarius spiral arm. Several H II regions are located at similar longitudes, but most are close to zero latitude and are more distant than the arm. The association contains the galactic cluster NGC 61993. The results suggest that the turbulence seen optically towards this cluster has been caused by the interaction between two cloud groups moving towards each other at velocities of 10 to 15 km/s.

  6. Methanotrophs, Methylosinus trichosporium OB3b, sMMO, and their application to bioremediation.

    PubMed

    Sullivan, J P; Dickinson, D; Chase, H A

    1998-01-01

    One of the most problematic groups of the USEPA and EU priority pollutants are the halogenated organic compounds. These substances have a wide range of industrial applications, such as solvents and cleaners. Inadequate disposal techniques and accidental spillages have led to their detection in soil, groundwater, and river sediments. Persistence of these compounds in the environment has resulted from low levels of biodegradation due to chemical structural features that preclude or retard biological attack. Research has indicated the idea that treatment systems based on methanotrophic co-metabolic transformation may be a cost-effective and efficient alternative to physical methods because of the potential for high transformation rates, the possibility of complete compound degradation without the formation of toxic metabolites, applicability to a broad spectrum of compounds, and the use of a widely available and inexpensive growth substrate. A substantial amount of work concerning methanotrophic cometabolic transformations has been carried out using the soluble form of methane monooxygenase (sMMO) from the obligate methanotroph Methylosinus trichosporium OB3b. This NADH-dependent monooxygenase is derepressed when cells are grown under copper stress. sMMO has a wider specificity than the particulate form. sMMO has been shown to degrade trichloroethylene (TCE) at a rate of at least one order of magnitude faster than obtained with other mixed and pure cultures, suggesting it has a wider application to bioremediation. Furthermore, sMMO catalyzes an unusually wide range of oxidation reactions, including the hydroxylation of alkanes, epoxidation of alkenes, ethers, halogenated methanes, cyclic and aromatic compounds including compounds, that are resistant to degradation in the environment. However, the practical application of methantrophs and Methylosinus trichosporium OB3b to the treatment of chlorinated organics has met with mixed success. Although oxidation rates are

  7. Differential regulation of insulin receptor substrates-1 and -2 (IRS-1 and IRS-2) and phosphatidylinositol 3-kinase isoforms in liver and muscle of the obese diabetic (ob/ob) mouse.

    PubMed Central

    Kerouz, N J; Hörsch, D; Pons, S; Kahn, C R

    1997-01-01

    Intracellular insulin signaling involves a series of alternative and complementary pathways created by the multiple substrates of the insulin receptor (IRS) and the various isoforms of SH2 domain signaling molecules that can interact with these substrates. In this study, we have evaluated the roles of IRS-1 and IRS-2 in signaling to the phosphatidylinositol (PI) 3-kinase pathway in the ob/ob mouse, a model of the insulin resistance of obesity and non-insulin-dependent diabetes mellitus. We find that the levels of expression of both IRS-1 and IRS-2 are decreased approximately 50% in muscle, whereas in liver the decrease is significantly greater for IRS-2 (72%) than for IRS-1 (29%). This results in differential decreases in IRS-1 and IRS-2 phosphorylation, docking of the p85alpha regulatory subunit of PI 3-kinase, and activation of this enzyme in these two insulin target tissues. In ob/ob liver there is also a change in expression of the alternatively spliced isoforms of the regulatory subunits for PI 3-kinase that was detected at the protein and mRNA level. This resulted in a 45% decrease in the p85alpha form of PI 3-kinase, a ninefold increase in the AS53/p55alpha, and a twofold increase in p50alpha isoforms. Thus, there are multiple alterations in the early steps of insulin signaling in the ob/ob mouse, with differential regulation of IRS-1 and IRS-2, various PI 3-kinase regulatory isoforms, and a lack of compensation for the decrease in insulin signaling by any of the known alternative pathways at these levels. PMID:9399964

  8. Seismicity and Attenuation of the Continental Margin Off New York and Southern/ New England from OBS Data

    NASA Astrophysics Data System (ADS)

    Ten Brink, U. S.; Flores, C. H.; McGuire, J. J.; Collins, J. A.

    2014-12-01

    Earthquake data recorded during two ocean-bottom-seismometer (OBS) deployments on the continental slope off New York and Southern New England are used to evaluate micro-seismicity and attenuation of the continental margin. The deployments were partly motivated by the detection by land seismometers of several ML2.5-3.8 continental margin earthquakes in this region during the previous four years. The data come from a five-month-long cluster deployment (1 km radius) of eleven short-period OBS in July 2012 at a water depth of ~835 m and a subsequent nine-month deployment of a network of five short-period OBS spaced 50 km apart at water depths between 900-2400 m. The land-based seismic network did not identify seismic activity on the margin during the two deployments. The OBS network located only one earthquake of ML~1 near the shelf edge, suggesting that seismic activity of the margin is probably successfully monitored by land seismometers. A successful land-based detection of earthquakes on the margin may indicate that low seismic attenuation extends from the Eastern U.S. to the continental shelf and slope. To better quantify the attenuation of the margin we derive the peak spectral attenuation of 6-8 ML2.8-4.1 earthquakes recorded by the OBS during the two deployments. These earthquakes were located on land close to shore and offshore between New Jersey and Nova Scotia, and propagation paths are almost entirely within the continental margin. Onshore earthquakes of ML ≤2.6 were not detected by the OBS. Information about the seismicity and attenuation of the margin will be used to evaluate the probability of earthquake-generated landslides.

  9. A Joint Monte Carlo Inversion of Seafloor Compliance, Receiver Functions and Rayleigh Wave Dispersion at OBS Stations off New Zealand

    NASA Astrophysics Data System (ADS)

    Ball, J. S.; Sheehan, A. F.; Stachnik, J. C.; Collins, J. A.

    2012-12-01

    Surface wave dispersion measurements, receiver functions and seafloor compliance data were jointly inverted to produce shear velocity profiles at Ocean Bottom Seismic (OBS) stations off the South Island of New Zealand. Receiver function analysis of OBS data presents a technical challenge due largely to the presence of multiply scattered reverberations in the water and low-velocity sediments at OBS sites. Teleseismic arrivals from interfaces of tectonic interest are obscured by sediment-converted shear waves and water column multiples. Mitigation of these effects typically requires accurate characterization of sediment layer shear velocities and thicknesses. The seismic properties of the sediment column can be probed using shallow mode-converted shear arrivals and the seafloor's response to ocean loading from infragravity waves (seafloor compliance). Data for this study were acquired in 2009-2010 by the Marine Observations of Anisotropy Near Aotearoa (MOANA) experiment, which deployed 30 broadband OBS and differential pressure gauges (DPGs) off the South Island of New Zealand. Seafloor compliance was calculated from MOANA DPG pressure and OBS vertical component acceleration power spectra at periods between 50-250s. The resulting compliance values range from 10-10-10-8 Pa-1 and are sensitive to changes in shear modulus at depths that increase with forcing period. Receiver functions were estimated using events of high SNR from epicentral distances of 30-90 degrees. Forward modeling utilized full-wavefield synthetic seismograms to account for the OBS location at the boundary between acoustic and elastic media. Rayleigh wave group velocity dispersion curves at periods from 6-30s were derived from ambient noise tomography. A Bayesian Markov Chain Monte Carlo algorithm was implemented to estimate shear velocity profiles, crustal and sediment thicknesses using these combined observations. Preliminary sediment thickness estimates range from 400m on the Challenger plateau to

  10. Ocean Basalt Simulator version 1 (OBS1): Trace element mass balance in adiabatic melting of a pyroxenite-bearing peridotite

    NASA Astrophysics Data System (ADS)

    Kimura, Jun-Ichi; Kawabata, Hiroshi

    2015-01-01

    present a new numerical trace element mass balance model for adiabatic melting of a pyroxenite-bearing peridotite for estimating mantle potential temperature, depth of melting column, and pyroxenite fraction in the source mantle for a primary ocean basalt/picrite. The Ocean Basalt Simulator version 1 (OBS1) uses a thermodynamic model of adiabatic melting of a pyroxenite-bearing peridotite with experimentally/thermodynamically parameterized liquidus-solidus intervals and source mineralogy. OBS1 can be used to calculate a sequence of adiabatic melting with two melting models, including (1) melting of peridotite and pyroxenite sources with simple mixing of their fractional melts (melt-melt mixing model), and (2) pyroxenite melting, melt metasomatism in the host peridotite, and melting of the metasomatized peridotite (source-metasomatism model). OBS1 can be used to explore (1) the fractions of peridotite and pyroxenite, (2) mantle potential temperature, (3) pressure of termination of melting, (4) degree of melting, and (5) residual mode of the sources. In order to constrain these parameters, the model calculates a mass balance for 26 incompatible trace elements in the sources and in the generated basalt/picrite. OBS1 is coded in an Excel spreadsheet and runs with VBA macros. Using OBS1, we examine the source compositions and conditions of the mid-oceanic ridge basalts, Loihi-Koolau basalts in the Hawaiian hot spot, and Jurassic Shatsky Rise and Mikabu oceanic plateau basalts and picrites. The OBS1 model shows the physical conditions, chemical mass balance, and amount of pyroxenite in the source peridotite, which are keys to global mantle recycling.

  11. VizieR Online Data Catalog: Cep OB2 Herschel/PACS view (Sicilia-Aguilar+, 2015)

    NASA Astrophysics Data System (ADS)

    Sicilia-Aguilar, A.; Roccatagliata, V.; Getman, K.; Riviere-Marichalar, P.; Birnstiel, T.; Merin, B.; Fang, M.; Henning, T.; Eiroa, C.; Currie, T.

    2015-02-01

    The Cep OB2 clusters, Tr 37 (centered at 21:38:09, +57:26:48, J2000) and NGC 7160 (centered at 21:53:40, 62:36:10, J2000), were observed with the ESA Herschel Space Observatory using the Photodetector Array Camera and Spectrometer (PACS), as part of the open time (OT) program "Disk dispersal in Cep OB2" (PI A. Sicilia-Aguilar). We obtained a total of 23h observing time in parallel mode at 70 and 160um. Observations took place between November 2012 and January 2013. (4 data files).

  12. Trace metals in the Ob and Yenisei Rivers' Estuaries (the Kara Sea).

    NASA Astrophysics Data System (ADS)

    Demina, L. L.

    2014-12-01

    Behavior of some trace metals (Al, As, Cd, Co, Cr, Cu, Fe, Mn, Ni and Pb) in water column (soluble <0.45 µm and particulate fractions) and bottom sediments (surface and cores) along the two transects from the Ob River and Yenisei River Estuaries to the Kara Sea was studied. The length of both transects was about 700 km. Water depth was 12-63 m, O2 dissolved :5.36-9.55 ml l-1. Along the transects salinity increased from 0.07 to 34.2 psu, while the SPM' concentration decreased from 10.31 to 0.31 mg/l. Total suspended particulate matter load is more than one order of magnitude higher in the Ob River Estuary comparing to that of the Yenisei River. It has led to a significant difference between the suspended trace metals' concentrations (µg/l) in water of the two estuaries. With salinity increase along transects Fe susp., Mn susp. and Zn susp. decreased by a factor of 100-500, that has led to a growth of a relative portion of dissolved trace metals followed by their bioaccumulation (Demina et al., 2010). A strong direct correlation between suspended Cu, Fe and SPM mass concentration was found. For the first time along the Yenisei River' Estuary -the Kara Sea transect a direct positive correlation between Cu suspended and volume concentration of SPM (mg/ml3) was found, that was attributed to contribution of phytoplankton aggregates in the SPM composition. A trend of relationship between content of suspended As and pelitic fraction (2-10 µm) of SPM was firstly found in theses basins also. Study of trace metal speciation in the bottom sediments (adsorbed, associated with Fe-Mn (oxyhydr)oxides, organic matter and fixed in the mineral lattice or refractory) has revealed the refractory fraction to be prevailing (70-95% total content) for Fe, Zn, Cu, Co, Ni, Cr, Cd and Pb. That means that toxic heavy metals were not available for bottom fauna. Mn was predominantly found in the adsorbed and (oxyhydr)oxides geochemically labile forms, reflecting the redox condition change

  13. MARS - CheObs ed. -- A flexible Software Framework for future Cherenkov Telescopes

    NASA Astrophysics Data System (ADS)

    Bretz, T.; Dorner, D.

    2010-04-01

    In gamma-ray astronomy, a new ground-based project named DWARF (Dedicated multiWavelength Agn Research Facility) is entering the field. It is a Cherenkov telescope project aimed at long-term monitoring of the brightest AGNs in the TeV energy range. One of the former HEGRA telescopes is being refurbished and upgraded with a Geigermode-APD camera. It is planned to be operated as a robotic telescope on the Canary Island of La Palma. Using new technologies, an improvement in sensitivity and an energy threshold of 400GeV are expected. Future plans foresee more small Cherenkov telescopes around the globe enabling for the first time 24 h monitoring in the VHE range. Long-term observations of the brightest AGNs provide the possibility to search for orbital modulation of blazar emission due to super-massive black hole binaries, to study the statistics of flares and their physical origin, and to correlate the data with corresponding data from the neutrino observatory IceCube to search for evidence of hadronic emission processes. For this project, a flexible and user friendly software package is available: Modular Analysis and Reconstruction Software - Cherenkov Observatory edition (MARS - CheObs ed.). The package provides a framework for any event-based analysis. For the application in the Imaging Air Cherenkov Technique, various methods and algorithms are available. Currently, it is being used for the MAGIC telescope. To allow for automatic analysis, MARS - CheObs ed. includes an automation concept which allows not only for automatic processing of the data, but also for automatic production of simulated data. For the DWARF project, a simulation program (ceres) has been developed and included in the software package. Using this, a design study for the technical upgrades of the telescope was performed. The simulation of the showers in the atmosphere is performed using the CORSIKA package. The output of this is fed into the telescope simulation ceres. Proper simulations are

  14. Magnetic field measurements and wind-line variability of OB-type stars

    NASA Astrophysics Data System (ADS)

    Schnerr, R. S.; Henrichs, H. F.; Neiner, C.; Verdugo, E.; de Jong, J.; Geers, V. C.; Wiersema, K.; van Dalen, B.; Tijani, A.; Plaggenborg, B.; Rygl, K. L. J.

    2008-06-01

    Context: The first magnetic fields in O- and B-type stars that do not belong to the Bp-star class, have been discovered. The cyclic UV wind-line variability, which has been observed in a significant fraction of early-type stars, is likely to be related to such magnetic fields. Aims: We attempt to improve our understanding of massive-star magnetic fields, and observe twenty-five carefully-selected, OB-type stars. Methods: Of these stars we obtain 136 magnetic field strength measurements. We present the UV wind-line variability of all selected targets and summarise spectropolarimetric observations acquired using the MUSICOS spectropolarimeter, mounted at the TBL, Pic du Midi, between December 1998 and November 2004. From the average Stokes I and V line profiles, derived using the LSD method, we measure the magnetic field strengths, radial velocities, and first moment of the line profiles. Results: No significant magnetic field is detected in any OB-type star that we observed. Typical 1σ errors are between 15 and 200 G. A possible magnetic-field detection for the O9V star 10 Lac remains uncertain, because the field measurements depend critically on the fringe-effect correction in the Stokes V spectra. We find excess emission in UV-wind lines, centred about the rest wavelength, to be a new indirect indicator of the presence of a magnetic field in early B-type stars. The most promising candidates to host magnetic fields are the B-type stars δ Cet and 6 Cep, and a number of O stars. Conclusions: Although some O and B stars have strong dipolar field, which cause periodic variability in the UV wind-lines, such strong fields are not widespread. If the variability observed in the UV wind-lines of OB stars is generally caused by surface magnetic fields, these fields are either weak (⪉few hundred G) or localised. Figures [see full textsee full textsee full textsee full textsee full textsee full text]-[see full textsee full textsee full textsee full textsee full textsee

  15. A new composite assembly mechanism for supporting QoS in OBS networks

    NASA Astrophysics Data System (ADS)

    Guan, Ai-hong; Hu, Fang; Li, Wan-chong

    2014-01-01

    To provide the differential quality of service (QoS) for different classes of packets and reduce the packet loss probability (PLP), a novel priority-based composite assembly scheme for optical burst switching (OBS) networks is proposed. The low and high packet classes are aggregated into a single burst simultaneously, and the highest-priority packets are placed in the middle, while the low-priority packets are at the tail and head of the burst. The priority is lowered gradually from the middle to the ends. Simulation results demonstrate that the proposed assembly strategy not only guarantees the integrity of the high-priority bursts, but also significantly reduces the average end-to-end delay of the bursts and the PLP of network. So it can adapt to the flexible network with QoS requirement.

  16. Low energy gamma ray emission from the Cygnus OB2 association

    NASA Technical Reports Server (NTRS)

    Chen, Wan; White, Richard L.

    1992-01-01

    According to our newly developed model of gamma-ray emission from chaotic early-type stellar winds, we predict the combined gamma-ray flux from the circumstellar winds of many very luminous early-type stars in the Cyg OB2 association can be detectable by the Energetic Gamma Ray Experiment Telescope (EGRET) (and maybe also by OSSE) on CGRO. Due to different radiation mechanisms, the gamma-ray spectrum from stellar winds can be quite different from that of CYG X-3; this spectral difference and the time-variation of Cyg X-3 flux will help to distinguish the gamma-ray components from different sources in this small region, which is spatially unresolvable by CGRO.

  17. Orion's Cloak - A rapidly expanding shell of gas centered on the Orion OB1 association

    NASA Technical Reports Server (NTRS)

    Cowie, L. L.; Songaila, A.; York, D. G.

    1979-01-01

    The structure of the interstellar gas surrounding the Orion OB1 association and the neighboring lambda Orionis association is detailed. UV absorption lime spectra of various ionization stages of C, N, Si and S in the directions of 12 stars were obtained by means of the spectrometer on board the Copernicus satellite. The presence of a shell of material surrounding the two associations and expanding at 100 to 120 km/sec, designated Orion's Cloak, was revealed, together with sporadically occurring higher column density matter at lower velocities. Results are interpreted to indicate the presence of a rapidly moving radiative shock outside the H II region of the association stars and inside this feature, a lower velocity, higher column density cloud which appears to be directly ionized by association stars. It is suggested that the gas features are caused by the effects of a recent supernova and of multiple supernovae, stellar winds and rocket-accelerated clouds in addition to stellar ionization.

  18. BOREAS RSS-17 Xylem Flux Density Measurements at the SSA-OBS Site

    NASA Technical Reports Server (NTRS)

    Zimmerman, Reiner; Way, JoBea; McDonald, Kyle; Nickeson, Jaime (Editor); Hall, Forrest G. (Editor); Smith, David E. (Technical Monitor)

    2000-01-01

    As part of its efforts to determine environmental and phenological states from radar imagery, the Boreal Ecosystem-Atmosphere Study (BOREAS) Remote Sensing Science (RSS)-17 team collected in situ tree xylem flow measurements for one growing season on five Picea mariana (black spruce) trees. The data were collected to obtain information on the temporal and spatial variability in water uptake by trees in the Southern Study Area-Old Black Spruce (SSA-OBS) stand in the BOREAS SSA. Temporally, the data were collected in 30-minute intervals for 120 days from 31 May 1994 until 27 September 1994. The data are stored in tabular ASCII files. The xylem flux data are available from the Earth Observing System Data and Information System (EOSDIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The data files are available on a CD-ROM (see document number 20010000884).

  19. Modeling the Radio Emission from Cyg OB2 No. 5: A Quadruple System?

    NASA Astrophysics Data System (ADS)

    Kennedy, M.; Dougherty, S. M.; Fink, A.; Williams, P. M.

    2010-02-01

    Fifty observations at frequencies between 1.4 GHz and 43 GHz of the 6.6 day O6.5-7+O5.5-6 binary Cyg OB2 No. 5 using the Very Large Array over 20 years are re-examined. The aim is to determine the location and character of the previously detected variable radio emission. The radio emission from the system consists of a primary component that is associated with the binary, and a non-thermal source (NE), 0farcs8 to the NE of the binary that has been ascribed to a wind-collision region (WCR) between the stellar winds of the binary and that of a B-type star (Star D) to the NE. Previous studies have not accounted for the potential contribution of NE to the total radio emission, most especially in observations where the primary and NE sources are not resolved as separate sources. NE shows no evidence of variation in 23 epochs where it is resolved separately from the primary radio component, demonstrating that the variable emission arises in the primary component. Since NE is non-variable, the radio flux from the primary can now be well determined for the first time, most especially in observations that do not resolve both the primary and NE components. The variable radio emission from the primary component has a period of 6.7 ± 0.3 years which is described by a simple model of a non-thermal source orbiting within the stellar wind envelope of the binary. Such a model implies the presence of a third, unresolved stellar companion (Star C) orbiting the 6.6 day binary with a period of 6.7 years and independent of Star D to the NE. The variable non-thermal emission arises from either a WCR between Star C and the binary system, or possibly from Star C directly. The model gives a mass-loss rate of 3.4 × 10-5 M sun yr-1 for Cyg OB2 No. 5, unusually high for an Of supergiant and comparable to that of WR stars, and consistent with an unusually strong He I 1.083 µm emission line, also redolent of WR stars. An examination of radial velocity observations available from the

  20. Kinematics of the galaxy from OB stars with proper motions from the Gaia DR1 catalogue

    NASA Astrophysics Data System (ADS)

    Bobylev, V. V.; Bajkova, A. T.

    2017-03-01

    We consider two samples of OB stars with different distance scales that we have studied previously. The first and second samples consist of massive spectroscopic binaries with photometric distances and distances determined from interstellar calcium lines, respectively. The OB stars are located at heliocentric distances up to 7 kpc. We have identified them with the Gaia DR1 catalogue. Using the proper motions taken from the Gaia DR1 catalogue is shown to reduce the random errors in the Galactic rotation parameters compared to the previously known results. By analyzing the proper motions and parallaxes of 208 OB stars from the Gaia DR1 catalogue with a relative parallax error of less than 200%, we have found the following kinematic parameters: ( U, V)⊙ = (8.67, 6.63)± (0.88, 0.98) km s-1, Ω0 = 27.35 ± 0.77 km s-1 kpc-1, Ω'0 = -4.13 ± 0.13 km s-1 kpc-2, and Ω″0 = 0.672 ± 0.070 km s-1 kpc-3, the Oort constants are A = -16.53 ± 0.52 km s-1 kpc-1 and B = 10.82 ± 0.93 km s-1 kpc-1, and the linear circular rotation velocity of the local standard of rest around the Galactic rotation axis is V 0 = 219 ± 8 km s-1 for the adopted R 0 = 8.0 ± 0.2 kpc. Based on the same stars, we have derived the rotation parameters only from their line-of-sight velocities. By comparing the estimated values of Ω'0, we have found the distance scale factor for the Gaia DR1 catalogue to be close to unity: 0.96. Based on 238 OB stars of the combined sample with photometric distances for the stars of the first sample and distances in the calcium distance scale for the stars of the second sample, line-of-sight velocities, and proper motions from the Gaia DR1 catalogue, we have found the following kinematic parameters: ( U, V, W)⊙ = (8.19, 9.28, 8.79)± (0.74, 0.92, 0.74) km s-1, Ω0 = 31.53 ± 0.54 km s-1 kpc-1, Ω'0 = -4.44 ± 0.12 km s-1 kpc-2, and Ω″0 = 0.706 ± 0.100 km s-1 kpc-3; here, A = -17.77 ± 0.46 km s-1 kpc-1, B = 13.76 ± 0.71 km s-1 kpc-1, and V 0 = 252 ± 8 km s-1.

  1. MODELING THE RADIO EMISSION FROM Cyg OB2 NO. 5: A QUADRUPLE SYSTEM?

    SciTech Connect

    Kennedy, M.; Dougherty, S. M.; Fink, A.; Williams, P. M. E-mail: sean.dougherty@nrc.c E-mail: pmw@roe.ac.u

    2010-02-01

    Fifty observations at frequencies between 1.4 GHz and 43 GHz of the 6.6 day O6.5-7+O5.5-6 binary Cyg OB2 No. 5 using the Very Large Array over 20 years are re-examined. The aim is to determine the location and character of the previously detected variable radio emission. The radio emission from the system consists of a primary component that is associated with the binary, and a non-thermal source (NE), 0.''8 to the NE of the binary that has been ascribed to a wind-collision region (WCR) between the stellar winds of the binary and that of a B-type star (Star D) to the NE. Previous studies have not accounted for the potential contribution of NE to the total radio emission, most especially in observations where the primary and NE sources are not resolved as separate sources. NE shows no evidence of variation in 23 epochs where it is resolved separately from the primary radio component, demonstrating that the variable emission arises in the primary component. Since NE is non-variable, the radio flux from the primary can now be well determined for the first time, most especially in observations that do not resolve both the primary and NE components. The variable radio emission from the primary component has a period of 6.7 +- 0.3 years which is described by a simple model of a non-thermal source orbiting within the stellar wind envelope of the binary. Such a model implies the presence of a third, unresolved stellar companion (Star C) orbiting the 6.6 day binary with a period of 6.7 years and independent of Star D to the NE. The variable non-thermal emission arises from either a WCR between Star C and the binary system, or possibly from Star C directly. The model gives a mass-loss rate of 3.4 x 10{sup -5} M{sub sun} yr{sup -1} for Cyg OB2 No. 5, unusually high for an Of supergiant and comparable to that of WR stars, and consistent with an unusually strong He I 1.083 mum emission line, also redolent of WR stars. An examination of radial velocity observations available

  2. OB associations and the nonuniversality of the cosmic abundances - Implications for cosmic rays and meteorites

    NASA Technical Reports Server (NTRS)

    Olive, K. A.; Schramm, D. N.

    1982-01-01

    The formation of the solar system inside an OB association is examined with particular attention to the elemental abundances which would have been ejected by the association's first few supernovae. It is found that the solar system material may have been significantly contaminated by these supernovae and thus the average interstellar composition may differ from the solar system composition. In particular, we find that many of the so-called isotopic and elemental abundance anomalies (e.g., Ne, C, O, s-process/r-process, etc.) found in meteoritic inclusions and in cosmic rays may be more representative of the average interstellar abundance. In other words, it may be that the average solar system abundances are what is 'anomalous'.

  3. A photometric study of the Orion OB 1 association. 1: Observational data

    NASA Technical Reports Server (NTRS)

    Warren, W. H., Jr.; Hesser, J. E.

    1976-01-01

    An extensive catalog of observational data is presented for stars in the region of the young stellar association Orion OB 1. In addition to new photoelectric observations obtained on the uvbyB and UBV systems, photoelectric and spectroscopic data were compiled for the stars observed and for several bright members of the association having available photometric indices. Mean weighted values were computed for the uvbyB and UBV data and are tabulated in summary tables which include all references for individual values. These tables are expected to be reasonably complete for association members earlier than spectral type A0. From an analysis of currently available proper motion, radial velocity, and photometric data, membership criteria were derived and qualitative membership probabilities for 526 stars were summarized. A set of charts is included for assistance in identification of the program stars in all regions of the association.

  4. A FORMATION SCENARIO OF YOUNG STELLAR GROUPS IN THE REGION OF THE SCORPIO CENTAURUS OB ASSOCIATION

    SciTech Connect

    Ortega, V. G.; Jilinski, E.; De la Reza, R.; Bazzanella, B.

    2009-04-15

    The main objective of this work is to investigate the role played by Lower Centaurus Crux (LCC) and Upper Centaurus Lupus (UCL), both subcomponents of the Scorpio Centaurus OB association (Sco-Cen), in the formation of the groups {beta} Pictoris, TW Hydrae, and the {eta} Chamaeleontis cluster. The dynamical evolution of all the stellar groups involved and of the bubbles and shells blown by LCC and UCL are calculated, and followed from the past to the present. This leads to a formation scenario in which (1) the groups {beta} Pictoris, TW Hydrae were formed in the wake of the shells created by LCC and UCL, (2) the young cluster {eta} Chamaeleontis was born as a consequence of the collision of the shells of LCC and UCL, and (3) the formation of Upper Scorpius (US), the other main subcomponent of the Sco-Cen association, may have been started by the same process that created {eta} Chamaeleontis.

  5. Nonalcoholic steatohepatitis (NASH) in ob/ob mice treated with yo jyo hen shi ko (YHK): effects on peroxisome proliferator-activated receptors (PPARs) and microsomal triglyceride transfer protein (MTP).

    PubMed

    Stefano, José Tadeu; de Oliveira, Claudia Pinto Marques Souza; Corrêa-Giannella, Maria Lúcia; de Lima, Vicência Mara Rodrigues; de Sá, Sandra Valéria; de Oliveira, Ellen Pierre; de Mello, Evandro Sobroza; Giannella-Neto, Daniel; Alves, Venâncio Avancini Ferreira; Carrilho, Flair José

    2007-12-01

    YHK has antioxidant properties, has a hypoglycemic effect, and may reduce plasma lipid levels. In this study, we examined the hepatic expression of PPAR-alpha and -gamma and MTP in ob/ob mice receiving or not receiving YHK. Ob/ob mice were assigned to receive oral YHK (20 mg/kg/day) fed solution (methionine/choline-deficient [MCD] diet+YHK group) or vehicle (MCD group) by gavage for 4 weeks. Liver fragments were collected for histologic examination and mRNA isolation. PPAR-alpha and -gamma and MTP gene expression was examined by RT-qPCR. YHK treatment was associated with NASH prevention, weight loss, and reduction of visceral fat and of serum concentrations of aminotransferases in comparison to the MCD group. YHK promoted an increment in PPAR-alpha and MTP and a decrement in PPAR-gamma mRNA contents. These findings suggest that modulation of PPAR-alpha and -gamma and MTP RNA expression may be implicated in the protective effect of YHK in experimental NASH, limiting hepatocyte lipid accumulation.

  6. Hydrodynamic effects on microcapillary motility and chemotaxis assays of Methylosinus trichosporium OB3b.

    PubMed Central

    Shonnard, D R; Taylor, R T; Tompson, A; Knapp, R B

    1992-01-01

    A study of the random motility and chemotaxis of Methylosinus trichosporium OB3b was conducted by using Palleroni-chamber microcapillary assay procedures. Under the growth conditions employed, this methanotroph was observed qualitatively with a microscope to be either slightly motile or essentially nonmotile. However, the cells did not not respond in the microcapillary assays in the manner expected for nonmotile Brownian particles. As a consequence, several hydrodynamic effects on these Palleroni microcapillary assays were uncovered. In the random-motility microcapillary assay, nondiffusive cell accumulations occurred that were strongly dependent upon cell concentration. An apparent minimal random-motility coefficient (mu) for this bacterial cell of 1.0 x 10(-7) cm2/s was estimated from microcapillary assays. A simple alternative spectrophotometric assay, based upon gravitational settling, was developed and shown to be an improvement over the Palleroni microcapillary motility assay for M. trichosporium OB3b in that it yielded a more-accurate threefold-lower random-motility coefficient. In addition, it provided a calculation of the gravitational-settling velocity. In the chemotaxis microcapillary assay, the apparent chemotactic responses were strongest for the highest test-chemical concentrations in the microcapillaries, were correlated with microcapillary fluid density, and were strongly dependent upon the microcapillary volume. A simple method to establish the maximal concentration of a chemical that can be tested and to quantify any contributions of abiotic convection is described. Investigators should be aware of the potential problems due to density-driven convection when using these commonly employed microcapillary assays for studying cells which have low motilities. PMID:1444383

  7. Cerium Regulates Expression of Alternative Methanol Dehydrogenases in Methylosinus trichosporium OB3b

    PubMed Central

    Farhan Ul Haque, Muhammad; Kalidass, Bhagyalakshmi; Bandow, Nathan; Turpin, Erick A.; DiSpirito, Alan A.

    2015-01-01

    Methanotrophs have multiple methane monooxygenases that are well known to be regulated by copper, i.e., a “copper switch.” At low copper/biomass ratios the soluble methane monooxygenase (sMMO) is expressed while expression and activity of the particulate methane monooxygenase (pMMO) increases with increasing availability of copper. In many methanotrophs there are also multiple methanol dehydrogenases (MeDHs), one based on Mxa and another based on Xox. Mxa-MeDH is known to have calcium in its active site, while Xox-MeDHs have been shown to have rare earth elements in their active site. We show here that the expression levels of Mxa-MeDH and Xox-MeDH in Methylosinus trichosporium OB3b significantly decreased and increased, respectively, when grown in the presence of cerium but the absence of copper compared to the absence of both metals. Expression of sMMO and pMMO was not affected. In the presence of copper, the effect of cerium on gene expression was less significant, i.e., expression of Mxa-MeDH in the presence of copper and cerium was slightly lower than in the presence of copper alone, but Xox-MeDH was again found to increase significantly. As expected, the addition of copper caused sMMO and pMMO expression levels to significantly decrease and increase, respectively, but the simultaneous addition of cerium had no discernible effect on MMO expression. As a result, it appears Mxa-MeDH can be uncoupled from methane oxidation by sMMO in M. trichosporium OB3b but not from pMMO. PMID:26296730

  8. SCUBA and HIRES Results for Protostellar Cores in the MON OB1 Dark Cloud

    NASA Astrophysics Data System (ADS)

    Wolf-Chase, G.; Moriarty-Schieven, G.; Fich, M.; Barsony, M.

    1999-05-01

    We have used HIRES-processing of IRAS data and point-source modelling techniques (Hurt & Barsony 1996; O'Linger 1997; Barsony et al. 1998), together with submillimeter continuum imaging using the Submillimeter Common-User Bolometer Array (SCUBA) on the 15-meter James Clerk Maxwell Telescope (JCMT), to search CS cores in the Mon OB1 dark cloud (Wolf-Chase, Walker, & Lada 1995; Wolf-Chase & Walker 1995) for deeply embedded sources. These observations, as well as follow-up millimeter photometry at the National Radio Astronomy Observatory (NRAO) 12-meter telescope on Kitt Peak, have lead to the identification of two Class 0 protostellar candidates, which were previously unresolved from two brighter IRAS point sources (IRAS 06382+0939 & IRAS 06381+1039) in this cloud. Until now, only one Class 0 object had been confirmed in Mon OB1; the driving source of the highly-collimated outflow NGC 2264 G (Ward-Thompson, Eiroa, & Casali 1995; Margulis et al. 1990; Lada & Fich 1996), which lies well outside the extended CS cores. One of the new Class 0 candidates may be an intermediate-mass source associated with an H_2O maser, and the other object is a low-mass source which may be associated with a near-infrared jet, and possibly with a molecular outflow. We report accurate positions for the new Class 0 candidates, based on the SCUBA images, and present new SEDs for these sources, as well as for the brighter IRAS point sources. A portion of this work was performed while GWC held a President's Fellowship from the University of California. MB and GWC gratefully acknowledge financial support from MB's NSF CAREER Grant, AST97-9753229.

  9. Cerium regulates expression of alternative methanol dehydrogenases in Methylosinus trichosporium OB3b.

    PubMed

    Farhan Ul Haque, Muhammad; Kalidass, Bhagyalakshmi; Bandow, Nathan; Turpin, Erick A; DiSpirito, Alan A; Semrau, Jeremy D

    2015-11-01

    Methanotrophs have multiple methane monooxygenases that are well known to be regulated by copper, i.e., a "copper switch." At low copper/biomass ratios the soluble methane monooxygenase (sMMO) is expressed while expression and activity of the particulate methane monooxygenase (pMMO) increases with increasing availability of copper. In many methanotrophs there are also multiple methanol dehydrogenases (MeDHs), one based on Mxa and another based on Xox. Mxa-MeDH is known to have calcium in its active site, while Xox-MeDHs have been shown to have rare earth elements in their active site. We show here that the expression levels of Mxa-MeDH and Xox-MeDH in Methylosinus trichosporium OB3b significantly decreased and increased, respectively, when grown in the presence of cerium but the absence of copper compared to the absence of both metals. Expression of sMMO and pMMO was not affected. In the presence of copper, the effect of cerium on gene expression was less significant, i.e., expression of Mxa-MeDH in the presence of copper and cerium was slightly lower than in the presence of copper alone, but Xox-MeDH was again found to increase significantly. As expected, the addition of copper caused sMMO and pMMO expression levels to significantly decrease and increase, respectively, but the simultaneous addition of cerium had no discernible effect on MMO expression. As a result, it appears Mxa-MeDH can be uncoupled from methane oxidation by sMMO in M. trichosporium OB3b but not from pMMO.

  10. Rewriting the Star-Formation History of the Nearest OB Association

    NASA Astrophysics Data System (ADS)

    Mamajek, Eric E.; Pecaut, Mark J.; Nguyen, Duy C.; Bubar, Eric J.

    2013-07-01

    The Sco-Cen (Sco OB2) OB association is the nearest region of recent massive star formation to the Sun. Sco-Cen is important for understanding the star-formation history of giant molecular cloud complexes, constraining circumstellar disk evolution, and providing samples of age-dated substellar objects and imaged planetary companions. Here we summarize some recent results on the classic Sco-Cen subgroups Upper Sco (US), Upper Cen-Lup (UCL), and Lower Cen-Cru (LCC): (1) isochronal analysis of the >1 Msun stars in the Upper Scorpius subgroup shows it to be twice as old as previously thought (˜11 Myr vs. ˜5 Myr), (2) analysis of high resolution optical spectra of FGK-type Sco-Cen members are consistent with the subgroups having solar metallicity, (3) we briefly describe a new subgroup dubbed "Lower Sco". Lastly, we find that the disk census of Sco-Cen members taken together are consistent with a protoplanetary disk fraction e-folding decay timescale of ˜4.5 Myr. This e-folding timescale is nearly twice that inferred previously for a large sample of nearby young stellar groups (~2.5 Myr ; see review of Mamajek 2009, AIPC, 1158, 3), but is consistent with the recent findings of Bell et al. (2013, MNRAS, in press; arxiv/1306.3237), which revised the ages of several benchmark clusters older by roughly a factor of two. The near doubling of the protoplanetary disk decay timescale may have important implications for inferring the lifetimes of early evolutionary stages of protostars, as well the efficiency of formation and subsequent migrational evolution of young gas giant planets.

  11. Stagnant Shells in the Vicinity of the Dusty Wolf–Rayet–OB Binary WR 112

    NASA Astrophysics Data System (ADS)

    Lau, R. M.; Hankins, M. J.; Schödel, R.; Sanchez-Bermudez, J.; Moffat, A. F. J.; Ressler, M. E.

    2017-02-01

    We present high spatial resolution mid-infrared images of the nebula around the late-type carbon-rich Wolf–Rayet (WC)–OB binary system WR 112 taken by the recently upgraded VLT spectrometer and imager for the mid-infrared (VISIR) with the PAH1, Ne ii_2, and Q3 filters. The observations reveal a morphology resembling a series of arc-like filaments and broken shells. Dust temperatures and masses are derived for each of the identified filamentary structures, which exhibit temperatures ranging from {179}-6+8 K at the exterior W2 filament to {355}-25+37 K in the central 3″. The total dust mass summed over the features is 2.6 ± 0.4 × 10‑5 M⊙. A multi-epoch analysis of mid-IR photometry of WR 112 over the past ∼20 years reveals no significant variability in the observed dust temperature and mass. The morphology of the mid-IR dust emission from WR 112 also exhibits no significant expansion from imaging data taken in 2001, 2007, and 2016, which disputes the current interpretation of the nebula as a high expansion velocity (∼1200 km s‑1) “pinwheel”-shaped outflow driven by the central WC–OB colliding-wind binary. An upper limit of ≲120 km s‑1 is derived for the expansion velocity assuming a distance of 4.15 kpc. The upper limit on the average total mass-loss rate from the central 3″ of WR 112 is estimated to be ≲8 × 10‑6 M⊙ year‑1. We leave its true nature as an open question, but propose that the WR 112 nebula may have formed in the outflow during a previous red or yellow supergiant phase of the central Wolf–Rayet star.

  12. γ-ray production in young open clusters: Berk 87, Cyg OB2 and Westerlund 2

    NASA Astrophysics Data System (ADS)

    Bednarek, W.

    2007-11-01

    Young open clusters are sites of cosmic ray acceleration as indicated by recent detections of the TeV γ-ray sources in the directions of two open clusters (Cyg OB2 and Westerlund 2). In fact, up to now a few different scenarios for acceleration of particles inside open clusters have been considered, i.e. shocks in massive star winds, pulsars and their nebulae, supernova shocks, massive compact binaries. Here we consider in detail the radiation processes due to both electrons and hadrons accelerated inside the open cluster. As a specific scenario, we apply the acceleration process at the shocks arising in the winds of Wolf-Rayet (WR) type stars. Particles diffuse through the medium of the open cluster during the activity time of the acceleration scenario defined by the age of the WR star. They interact with the matter and radiation, at first inside the open cluster and, later in the dense surrounding clouds. We calculate the broad-band spectrum in different processes for three exemplary open clusters (Berk 87, Cyg OB2, Westerlund 2) for which the best observational constraints on the spectra are at present available. It is assumed that the high-energy phenomena, observed from the X-ray up to the GeV-TeV γ-ray energies, are related to each other. We conclude that the most likely description of the radiation processes in these objects is achieved in the hybrid (leptonic-hadronic) model in which leptons are responsible for the observed X-ray and GeV γ-ray emission and hadrons are responsible for the TeV γ-ray emission.

  13. Distribution of global fallouts cesium-137 in taiga and tundra catenae at the Ob River basin

    NASA Astrophysics Data System (ADS)

    Semenkov, I. N.; Usacheva, A. A.; Miroshnikov, A. Yu.

    2015-03-01

    The classification of soil catenae at the Ob River basin is developed and applied. This classification reflects the diverse geochemical conditions that led to the formation of certain soil bodies, their combinations and the migration fields of chemical elements. The soil and geochemical diversity of the Ob River basin catenae was analyzed. The vertical and lateral distribution of global fallouts cesium-137 was studied using the example of the four most common catenae types in Western Siberia tundra and taiga. In landscapes of dwarf birches and dark coniferous forests on gleysols, cryosols, podzols, and cryic-stagnosols, the highest 137Cs activity density and specific activity are characteristic of the upper soil layer of over 30% ash, while the moss-grass-shrub cover is characterized by low 137Cs activity density and specific activity. In landscapes of dwarf birches and pine woods on podzols, the maximum specific activity of cesium-137 is typical for moss-grass-shrub cover, while the maximum reserves are concentrated in the upper soil layer of over 30% ash. Bog landscapes and moss-grass-shrub cover are characterized by a minimum activity of 137Cs, and its reserves in soil generally decrease exponentially with depth. The cesium-137 penetration depth increases in oligotrophic histosols from northern to middle taiga landscapes from 10-15 to 40 cm. 137Cs is accumulated in oligotrophic histosols for increases in pH from 3.3 to 4.0 and in concretionary interlayers of pisoplinthic-cryic-histic-stagnosols. Cryogenic movement, on the one hand, leads to burying organic layers enriched in 137Cs and, on the other hand, to deducing specific activity when mixed with low-active material from lower soil layers.

  14. Colliding filaments and a massive dense core in the Cygnus OB 7 molecular cloud

    SciTech Connect

    Dobashi, Kazuhito; Shimoikura, Tomomi; Akisato, Ko; Ohashi, Kenjiro; Nakagomi, Keisuke; Matsumoto, Tomoaki; Saito, Hiro

    2014-12-10

    We report the results of molecular line observations carried out toward a massive dense core in the Cyg OB 7 molecular cloud. The core has an extraordinarily large mass (∼1.1 × 10{sup 4} M {sub ☉}) and size (∼2 × 5 pc{sup 2}), but there is no massive young star forming therein. We observed this core in various molecular lines such as C{sup 18}O(J = 1-0) using the 45 m telescope at Nobeyama Radio Observatory. We find that the core has an elongated morphology consisting of several filaments and core-like structures. The filaments are massive (10{sup 2}-10{sup 3} M {sub ☉}), and they are apparently colliding with one another. Some candidates for young stellar objects are distributed around their intersection, suggesting that the collisions of the filaments may have influenced their formation. To understand the formation and evolution of such colliding filaments, we performed numerical simulations using the adaptive mesh refinement technique, adopting the observed core parameters (the mass and size) as the initial conditions. The results indicate that the filaments are formed as seen in other earlier simulations for small cores in the literature, but we could not reproduce the collisions of the filaments simply by assuming a large initial mass and size. We find that collisions of the filaments occur only when there is a large velocity gradient in the initial core, in a sense compressing it. We suggest that the observed core was actually compressed by an external effect, e.g., shocks from nearby supernova remnants, including HB 21 which has been suggested to be interacting with the Cyg OB 7 molecular cloud.

  15. On the observability of bow shocks of Galactic runaway OB stars

    NASA Astrophysics Data System (ADS)

    Meyer, D. M.-A.; van Marle, A.-J.; Kuiper, R.; Kley, W.

    2016-06-01

    Massive stars that have been ejected from their parent cluster and supersonically sailing away through the interstellar medium (ISM) are classified as exiled. They generate circumstellar bow-shock nebulae that can be observed. We present two-dimensional, axisymmetric hydrodynamical simulations of a representative sample of stellar wind bow shocks from Galactic OB stars in an ambient medium of densities ranging from nISM = 0.01 up to 10.0 cm- 3. Independently of their location in the Galaxy, we confirm that the infrared is the most appropriated waveband to search for bow shocks from massive stars. Their spectral energy distribution is the convenient tool to analyse them since their emission does not depend on the temporary effects which could affect unstable, thin-shelled bow shocks. Our numerical models of Galactic bow shocks generated by high-mass ( ≈ 40 M⊙) runaway stars yield H α fluxes which could be observed by facilities such as the SuperCOSMOS H-Alpha Survey. The brightest bow-shock nebulae are produced in the denser regions of the ISM. We predict that bow shocks in the field observed at H α by means of Rayleigh-sensitive facilities are formed around stars of initial mass larger than about 20 M⊙. Our models of bow shocks from OB stars have the emission maximum in the wavelength range 3 ≤ λ ≤ 50 μm which can be up to several orders of magnitude brighter than the runaway stars themselves, particularly for stars of initial mass larger than 20 M⊙.

  16. Controlling the onset of OB/OM in a semiconductor quantum well system in an inverted Y-type configuration

    NASA Astrophysics Data System (ADS)

    Raheli, Ali; Hamedi, H. R.; Sahrai, M.

    2016-01-01

    The problem of optical bistability (OB) and optical multistability (OM) is numerically investigated in a four-level inverted Y-type semiconductor quantum well (SQW) structure immersed in a unidirectional ring cavity. In the four-level SQW system under consideration, a closed loop configuration is coupled to the upper level through a tunable probe field. We show that the OB threshold intensity can be controlled via the intensity of coupling fields which gives rise to the absorption variation of the probe field. In addition, due to the existence of the closed-loop configuration, the OB and OM behaviors of the proposed SQW medium are dependent on the relative phase of the applied fields. It is found that the OB can be switched to OM or vice versa by properly adjusting the relative phase of the applied fields. The results may provide new possibilities in real experiments for realizing an all-optical switching or coding element in a solid-state platform.

  17. Work and Family Research in IO/OB: Content Analysis and Review of the Literature (1980-2002)

    ERIC Educational Resources Information Center

    Eby, Lillian T.; Casper, Wendy J.; Lockwood, Angie; Bordeaux, Chris; Brinley, Andi

    2005-01-01

    This monograph reviews 190 work-family studies published in IO/OB journals from 1980 to 2002. The results of a content analysis are presented which catalog these articles with respect to the study focus, nature and direction of the proposed effects, and predictor, criterion, and mediator variables examined. Then a narrative review of the articles…

  18. Uptake and effect of rare earth elements on gene expression in Methylosinus trichosporium OB3b

    SciTech Connect

    Gu, Wenyu; Farhan Ul Haque, Muhammad; DiSpirito, Alan A.; Semrau, Jeremy D.

    2016-05-12

    It is well-known that M. trichosporium OB3b has two forms of methane monooxygenase responsible for the initial conversion of methane to methanol, a cytoplasmic (soluble) methane monooxygenase (sMMO) and a membrane-associated (particulate) methane monooxygenase (pMMO) and that copper strongly regulates expression of these alternative forms of MMO. More recently, it has been discovered that M. trichosporium OB3b has multiple types of the methanol dehydrogenase (MeDH), i.e. the Mxa-MeDH and Xox-MeDH, and the expression of these two forms is regulated by the availability of the rare earth element, cerium. Here we extend these studies and show that lanthanum, praseodymium, neodymium and samarium also regulate expression of alternative forms of MeDH. The effect of these rare earth elements on MeDH expression, however, was only observed in the absence of copper. Further, a mutant of M. trichosporium OB3b where the Mxa-MeDH was knocked out was able to grow in the presence of lanthanum, praseodymium and neodymium, but was not able to grow in the presence of samarium. In conclusion, collectively these data suggest that multiple levels of gene regulation by metals exist in M. trichosporium OB3b but that copper overrides the effect of other metals by an as yet unknown mechanism.

  19. Crystal Structures of RMI1 and RMI2, Two OB-Fold Regulatory Subunits of the BLM Complex

    SciTech Connect

    Wang, Feng; Yang, Yuting; Singh, Thiyam Ramsing; Busygina, Valeria; Guo, Rong; Wan, Ke; Wang, Weidong; Sung, Patrick; Meetei, Amom Ruhikanta; Lei, Ming

    2010-11-05

    Mutations in BLM, a RecQ-like helicase, are linked to the autosomal recessive cancer-prone disorder Bloom's syndrome. BLM associates with topoisomerase (Topo) III{alpha}, RMI1, and RMI2 to form the BLM complex that is essential for genome stability. The RMI1-RMI2 heterodimer stimulates the dissolution of double Holliday junction into non-crossover recombinants mediated by BLM-Topo III{alpha} and is essential for stabilizing the BLM complex. However, the molecular basis of these functions of RMI1 and RMI2 remains unclear. Here we report the crystal structures of multiple domains of RMI1-RMI2, providing direct confirmation of the existence of three oligonucleotide/oligosaccharide binding (OB)-folds in RMI1-RMI2. Our structural and biochemical analyses revealed an unexpected insertion motif in RMI1N-OB, which is important for stimulating the dHJ dissolution. We also revealed the structural basis of the interaction between RMI1C-OB and RMI2-OB and demonstrated the functional importance of the RMI1-RMI2 interaction in genome stability maintenance.

  20. Methanol suppression of trichloroethylene degradation by Methylosinus trichosporium (OB3b) and methane-oxidizing mixed cultures

    SciTech Connect

    Eng, W.; Palumbo, A.V.; Strandberg, G.W.; Sriharan, S.

    1991-12-31

    The effect of methanol on trichloroethylene (TCE) degradation by mixed and pure methylotrophic cultures was examined in batch culture experiments. Methanol was found to relieve growth inhibition of Methylosinus trichosporium (OB3b) at high (14 mg/L) TCE concentrations. Degradation of TCE was determined by both radiolabeling and gas chromatography techniques. When cultures were grown on methanol over 10 to 14 d with 0.3 mg/L TCE, OB3b degraded 16.89 {+-} 0.82% (mean {+-} SD) of the TCE, and a mixed culture (DT type II) degraded 4.55 {+-} 0.11%. Mixed culture (JS type I) degraded 4.34 {+-} 0.06% of the TCE. When grown on methane with 0.3 mg/L TCE, 32.93 {+-} 2.01% of the TCE was degraded by OB3b, whereas the JS culture degraded 24.3 {+-} 1.38% of the TCE, and the DT culture degraded 34.3 {+-} 2.97% of the TCE. The addition of methanol to cultures grown on methane reduced TCE degradation to 16.21 {+-} 1.17% for OB3b and to 5.08 {+-} 0.56% for JS. Although methanol reduces the toxicity of TCE to the cultures, biodegradation of TCE cannot be sustained in methanol-grown cultures. Since high TCE concentrations appear to inhibit methane uptake and growth, we suggest the primary toxicity of TCE is directed towards the methane monooxygenase.

  1. Structure-guided mutational analysis of the OB, HhH, and BRCT domains of Escherichia coli DNA ligase.

    PubMed

    Wang, Li Kai; Nair, Pravin A; Shuman, Stewart

    2008-08-22

    NAD(+)-dependent DNA ligases (LigAs) are ubiquitous in bacteria and essential for growth. LigA enzymes have a modular structure in which a central catalytic core composed of nucleotidyltransferase and oligonucleotide-binding (OB) domains is linked via a tetracysteine zinc finger to distal helix-hairpin-helix (HhH) and BRCT (BRCA1-like C-terminal) domains. The OB and HhH domains contribute prominently to the protein clamp formed by LigA around nicked duplex DNA. Here we conducted a structure-function analysis of the OB and HhH domains of Escherichia coli LigA by alanine scanning and conservative substitutions, entailing 43 mutations at 22 amino acids. We thereby identified essential functional groups in the OB domain that engage the DNA phosphodiester backbone flanking the nick (Arg(333)); penetrate the minor grove and distort the nick (Val(383) and Ile(384)); or stabilize the OB fold (Arg(379)). The essential constituents of the HhH domain include: four glycines (Gly(455), Gly(489), Gly(521), Gly(553)), which bind the phosphate backbone across the minor groove at the outer margins of the LigA-DNA interface; Arg(487), which penetrates the minor groove at the outer margin on the 3 (R)-OH side of the nick; and Arg(446), which promotes protein clamp formation via contacts to the nucleotidyltransferase domain. We find that the BRCT domain is required in its entirety for effective nick sealing and AMP-dependent supercoil relaxation.

  2. Waveform Inversion of OBS Data and Illumination/Resolution Analyses on Marine Seismic Data Acquisitions by the Adjoint Wavefield Method

    NASA Astrophysics Data System (ADS)

    Chen, H.; Li, K.

    2012-12-01

    We applied a wave-equation based adjoint wavefield method for seismic illumination/resolution analyses and full waveform inversion. A two-way wave-equation is used to calculate directional and diffracted energy fluxes for waves propagating between sources and receivers to the subsurface target. The first-order staggered-grid pressure-velocity formulation, which lacks the characteristic of being self-adjoint is further validated and corrected to render the modeling operator before its practical application. Despite most published papers on synthetic kernel research, realistic applications to two field experiments are demonstrated and emphasize its practical needs. The Fréchet sensitivity kernels are used to quantify the target illumination conditions. For realistic illumination measurements and resolution analyses, two completely different survey geometries and nontrivial pre-conditioning strategies based on seismic data type are demonstrated and compared. From illumination studies, particle velocity responses are more sensitive to lateral velocity variations than pressure records. For waveform inversion, the more accurately estimated velocity model obtained the deeper the depth of investigation would be reached. To achieve better resolution and illumination, closely spaced OBS receiver interval is preferred. Based on the results, waveform inversion is applied for a gas hydrate site in Taiwan for shallow structure and BSR detection. Full waveform approach potentially provides better depth resolution than ray approach. The quantitative analyses, a by-product of full waveform inversion, are useful for quantifying seismic processing and depth migration strategies.llumination/resolution analysis for a 3D MCS/OBS survey in 2008. Analysis of OBS data shows that pressure (top), horizontal (middle) and vertical (bottom) velocity records produce different resolving power for gas hydrate exploration. ull waveform inversion of 8 OBS data along Yuan-An Ridge in SW Taiwan

  3. Methanobactin from Methylocystis sp. strain SB2 affects gene expression and methane monooxygenase activity in Methylosinus trichosporium OB3b.

    PubMed

    Farhan Ul-Haque, Muhammad; Kalidass, Bhagyalakshmi; Vorobev, Alexey; Baral, Bipin S; DiSpirito, Alan A; Semrau, Jeremy D

    2015-04-01

    Methanotrophs can express a cytoplasmic (soluble) methane monooxygenase (sMMO) or membrane-bound (particulate) methane monooxygenase (pMMO). Expression of these MMOs is strongly regulated by the availability of copper. Many methanotrophs have been found to synthesize a novel compound, methanobactin (Mb), that is responsible for the uptake of copper, and methanobactin produced by Methylosinus trichosporium OB3b plays a key role in controlling expression of MMO genes in this strain. As all known forms of methanobactin are structurally similar, it was hypothesized that methanobactin from one methanotroph may alter gene expression in another. When Methylosinus trichosporium OB3b was grown in the presence of 1 μM CuCl2, expression of mmoX, encoding a subunit of the hydroxylase component of sMMO, was very low. mmoX expression increased, however, when methanobactin from Methylocystis sp. strain SB2 (SB2-Mb) was added, as did whole-cell sMMO activity, but there was no significant change in the amount of copper associated with M. trichosporium OB3b. If M. trichosporium OB3b was grown in the absence of CuCl2, the mmoX expression level was high but decreased by several orders of magnitude if copper prebound to SB2-Mb (Cu-SB2-Mb) was added, and biomass-associated copper was increased. Exposure of Methylosinus trichosporium OB3b to SB2-Mb had no effect on expression of mbnA, encoding the polypeptide precursor of methanobactin in either the presence or absence of CuCl2. mbnA expression, however, was reduced when Cu-SB2-Mb was added in both the absence and presence of CuCl2. These data suggest that methanobactin acts as a general signaling molecule in methanotrophs and that methanobactin "piracy" may be commonplace.

  4. The 2.35 year itch of Cygnus OB2 #9. II. Radio monitoring

    NASA Astrophysics Data System (ADS)

    Blomme, R.; Nazé, Y.; Volpi, D.; De Becker, M.; Prinja, R. K.; Pittard, J. M.; Parkin, E. R.; Absil, O.

    2013-02-01

    Context. Cyg OB2 #9 is one of a small set of non-thermal radio emitting massive O-star binaries. The non-thermal radiation is due to synchrotron emission in the colliding-wind region. Cyg OB2 #9 has only recently been discovered to be a binary system, and a multi-wavelength campaign was organized to study its 2011 periastron passage. Aims: We want to better determine the parameters of this system and model the wind-wind collision. This will lead to a better understanding of the Fermi mechanism that accelerates electrons up to relativistic speeds in shocks and its occurrence in colliding-wind binaries. We report here on the results of the radio observations obtained in the monitoring campaign and present a simple model to interpret the data. Methods: We used the Expanded Very Large Array (EVLA) radio interferometer to obtain 6 cm and 20 cm continuum fluxes during the Cyg OB2 #9 periastron passage in 2011. We introduce a simple model to solve the radiative transfer in the stellar winds and the colliding-wind region, and thus determine the expected behaviour of the radio light curve. Results: The observed radio light curve shows a steep drop in flux sometime before periastron. The fluxes drop to a level that is comparable to the expected free-free emission from the stellar winds, suggesting that the non-thermal emitting region is completely hidden at that time. After periastron passage, the fluxes slowly increase. We use the asymmetry of the light curve to show that the primary has the stronger wind. This is somewhat unexpected if we use the astrophysical parameters based on theoretical calibrations. But it becomes entirely feasible if we take into account that a given spectral type-luminosity class combination covers a range of astrophysical parameters. The colliding-wind region also contributes to the free-free emission, which can help explain the high values of the spectral index seen after periastron passage. Combining our data with older Very Large Array (VLA

  5. Exploring the Full Stellar Population of the Upper Scorpius OB Association

    NASA Astrophysics Data System (ADS)

    Preibisch, Thomas; Brown, Anthony G. A.; Bridges, Terry; Guenther, Eike; Zinnecker, Hans

    2002-07-01

    We investigate the stellar population and star formation history of the Upper Scorpius OB association, the most nearby region of recent massive star formation, over the full stellar mass range from 0.1 to 20 Msolar. The first part of this paper describes an extension of our large spectroscopic survey (Preibisch et al., published in 2001) for low-mass pre-main-sequence (PMS) stars in Upper Scorpius. Using the multiobject spectrograph 2dF at the Anglo-Australian Telescope, we obtained spectra of 469 stars with magnitudes R=12.5-18.0 in a 6 deg2 area. Among these, we find 68 new PMS stars, nearly all of them M-type stars, by their strong lithium absorption lines. The total area covered by our 2dF survey is now 9 deg2 and contains 166 new PMS stars. Combining these results with our earlier investigation (Preibisch & Zinnecker) yields a sample of 250 PMS stars in the mass range ~0.1 to ~2 Msolar. The location of these stars in the HR diagram suggests a mean age of 5 Myr without a significant age spread. In the second part of this paper, we also consider the population of 114 high-mass members identified in detailed Hipparcos studies. We construct a combined HR diagram for the 364 high- and low-mass members and find that the whole stellar population is very well characterized by a very narrow age distribution around 5 Myr. We estimate individual masses for all members and construct an empirical mass function covering the mass range from 0.1 up to 20 Msolar. A power-law fit to the mass function gives a slope of α~-2.6 above ~2 Msolar and a much flatter slope (α~-0.9) below ~0.6 Msolar. The initial mass function of Upper Sco is not identical, but within the errors consistent with recent determinations of the field initial mass function. There is certainly no deficit of low-mass stars in the Upper Sco OB association, but rather a small excess of low-mass stars. Our results on the stellar age distribution confirm earlier indications that the star formation process in Upper

  6. Photoluminescence properties of Pr3+ doped Bi2ZnOB2O6 microcrystals and PMMA-based composites

    NASA Astrophysics Data System (ADS)

    Jaroszewski, K.; Chrunik, M.; Głuchowski, P.; Coy, E.; Maciejewska, B.; Jastrzab, R.; Majchrowski, A.; Kasprowicz, D.

    2016-12-01

    Photoluminescence properties of red-emitting Pr3+-doped Bi2ZnOB2O6 microcrystalline powder and PMMA-based composite materials were reported. Bi2ZnOB2O6:Pr3+ powders were synthesized by means of the modified Pechini method. The morphology and crystallographic structure of Bi2ZnOB2O6:Pr3+ microcrystals were investigated by XRD and HRTEM. The PMMA-based composite materials were prepared by embedding of Bi2ZnOB2O6:Pr3+ powder in the PMMA matrix. The vibrational properties of the powder and composite systems were investigated by μ-Raman spectroscopy. Emission spectra of the samples were measured under blue (451.6 nm) and UV (320 nm) excitation. Both, the powder and composite samples show enhancement of red emission (1D2 → 3H4) and quenching of greenish-blue luminescence from 3P0 level of Pr3+ ions after excitation in UV and VIS caused by the 3P0 ∼ 1D2 non-radiative relaxation of Pr3+ ion by low-lying charge transfer state and non-radiative de-excitation through Pr3+-Bi3+ energy transfer. The response of the powder and composite samples to pulsed excitation at 451.6 nm was measured by monitoring emission from the 1D2 level (595 nm/3P0 → 3H6 transition). The determined lifetimes τ1 and τ2 of the red emission at 595 nm (1D2 → 3H4 transition) of the composite are significantly longer in comparison to powder samples. Moreover, because of the good nonlinear optical properties of the Bi2ZnOB2O6 crystals and effective luminescence of the Pr3+-doped Bi2ZnOB2O6 powders and composites, they can be very useful as bi-functional materials in the new generation of optoelectronic devices.

  7. No Evidence for Protoplanetary Disk Destruction By OB Stars in the MYStIX Sample

    NASA Astrophysics Data System (ADS)

    Richert, Alexander J. W.; Feigelson, Eric D.; Getman, Konstantin V.; Kuhn, Michael A.

    2015-09-01

    Hubble Space Telescope images of proplyds in the Orion Nebula, as well as submillimeter/radio measurements, show that the dominant O7 star {θ }1Ori C photoevaporates nearby disks around pre-main-sequence stars. Theory predicts that massive stars photoevaporate disks within distances of the order of 0.1 pc. These findings suggest that young, OB-dominated massive H ii regions are inhospitable to the survival of protoplanetary disks and, subsequently, to the formation and evolution of planets. In the current work, we test this hypothesis using large samples of pre-main-sequence stars in 20 massive star-forming regions selected with X-ray and infrared photometry in the MYStIX survey. Complete disk destruction would lead to a deficit of cluster members with an excess in JHKS and Spitzer/IRAC bands in the vicinity of O stars. In four MYStIX regions containing O stars and a sufficient surface density of disk-bearing sources to reliably test for spatial avoidance, we find no evidence for the depletion of inner disks around pre-main-sequence stars in the vicinity of O-type stars, even very luminous O2-O5 stars. These results suggest that massive star-forming regions are not very hostile to the survival of protoplanetary disks and, presumably, to the formation of planets.

  8. A Deuteration Survey of the Clump Population in the Gemini OB1 Molecular Cloud

    NASA Astrophysics Data System (ADS)

    Henrici, Andrew Scott; Shirley, Yancy L.; Svoboda, Brian E.

    2017-01-01

    Recent maps of dust continuum emission from entire molecular clouds at submillimeter wavelengths have made it possible to survey and study the chemistry of entire core and clump populations within a single cloud. One very strong chemical process in star-forming regions is the fractionation of deuterium in molecules, which results in an increase in the deuterium ratio many orders of magnitude over the ISM [D]/[H] ratio and provides a chemical probe of cold, dense regions. We present a survey of DCO+ 3-2 and N2D+ 3-2 toward the clump population in the high-mass, star-forming Gemini OB1 Molecular Cloud identified from 1.1 mm continuum imaging by the Bolocam Galactic Plane Survey. The peak 1.1 mm continuum positions of 52 clumps in the range 188°≤ l ≤194° were observed with the 10m Heinrich Hertz Submillimeter Telescope. We find that DCO+ emission is detected toward 90% of the clumps with a median deuterium ratio of 0.01 while N2D+ emission is detected toward only 25% of the clumps. The DCO+ fractionation anti-correlates with gas kinetic temperature and linewidth, a measure of the amount of turbulence within the clumps. We compare the deuteration ratios of with physical properties of the clumps and their evolutionary stage.

  9. Intermediate scale structure of the interstellar medium towards NGC 6231 in Sco OB1 with FUSE

    NASA Astrophysics Data System (ADS)

    Marggraf, O.; Bluhm, H.; de Boer, K. S.

    2004-03-01

    The FUSE far-ultraviolet interstellar spectra toward seven targets in NGC 6231 show that the molecules H2, HD, and CO as well as various atomic species are distributed in several clouds. The main absorption component found on the sight lines lies in the Lupus cloud region at a distance of about 150 pc, and there is a weaker second one, presumably in the Sco OB1 shell surrounding NGC 6231 (d≃1.8 kpc). H2 excitation modelling is used to constrain the radiation field and the density in the gas; HD is used to estimate the abundance of H+. The small angular separation of the target stars allows column density variations to be probed over the field of view, on scales of 0.05 pc in the case of the Lupus cloud distance. They are 40% for H2 and 60% for H I. A rather strong radiation field inside the molecular clouds suggests a separation of the gas into smaller cloudlets also along the line of sight. Based on observations made with the NASA-CNES-CSA Far Ultraviolet Spectroscopic Explorer. FUSE is operated for NASA by the Johns Hopkins University under NASA contract NAS5-32985.

  10. Massive open star clusters using the VVV survey. V. Young clusters with an OB stellar population

    NASA Astrophysics Data System (ADS)

    Ramírez Alegría, S.; Borissova, J.; Chené, A.-N.; Bonatto, C.; Kurtev, R.; Amigo, P.; Kuhn, M.; Gromadzki, M.; Carballo-Bello, J. A.

    2016-04-01

    Context. The ESO public survey VISTA Variables in the Vía Láctea (VVV) has contributed with deep multi-epoch photometry of the Galactic bulge and the adjacent part of the disk over 526 sq. deg. More than a hundred cluster candidates have been reported thanks to this survey. Aims: We present the fifth article in a series of papers focused on young and massive clusters discovered in the VVV survey. In this paper, we present the physical characterization of five clusters with a spectroscopically confirmed OB-type stellar population. Methods: To characterize the clusters, we used near-infrared photometry (J, H, and KS) from the VVV survey and near-infrared K-band spectroscopy from ISAAC at VLT, following the methodology presented in the previous articles of the series. Results: All clusters in our sample are very young (ages between 1-20 Myr), and their total mass are between (1.07+0.40-0.30)×102 M⊙ and (4.17+4.15-2.08)×103 M⊙. We observed a relation between the clusters total mass Mecl and the mass of their most massive stellar member mmax, for clusters with an age <10 Myr. Based on observations taken within the ESO VISTA Public Survey VVV (programme ID 179.B-2002), and with ISAAC/VLT (programme 087.D-0341(A)).

  11. DIRECT IMAGING AND SPECTROSCOPY OF A YOUNG EXTRASOLAR KUIPER BELT IN THE NEAREST OB ASSOCIATION

    SciTech Connect

    Currie, Thayne; Lisse, Carey M.; Kuchner, Marc; Madhusudhan, Nikku; Kenyon, Scott J.; Thalmann, Christian; Carson, Joseph; Debes, John

    2015-07-01

    We describe the discovery of a bright, young Kuiper belt–like debris disk around HD 115600, a ∼1.4–1.5 M{sub ⊙}, ∼15 Myr old member of the Sco–Cen OB Association. Our H-band coronagraphy/integral field spectroscopy from the Gemini Planet Imager shows the ring has a (luminosity-scaled) semimajor axis of (∼22 AU) ∼ 48 AU, similar to the current Kuiper belt. The disk appears to have neutral-scattering dust, is eccentric (e ∼ 0.1–0.2), and could be sculpted by analogs to the outer solar system planets. Spectroscopy of the disk ansae reveal a slightly blue to gray disk color, consistent with major Kuiper belt chemical constituents, where water ice is a very plausible dominant constituent. Besides being the first object discovered with the next generation of extreme adaptive optics systems (i.e., SCExAO, GPI, SPHERE), HD 115600's debris ring and planetary system provide a key reference point for the early evolution of the solar system, the structure, and composition of the Kuiper belt and the interaction between debris disks and planets.

  12. New Version of SeismicHandler (SHX) based on ObsPy

    NASA Astrophysics Data System (ADS)

    Stammler, Klaus; Walther, Marcus

    2016-04-01

    The command line version of SeismicHandler (SH), a scientific analysis tool for seismic waveform data developed around 1990, has been redesigned in the recent years, based on a project funded by the Deutsche Forschungsgemeinschaft (DFG). The aim was to address new data access techniques, simplified metadata handling and a modularized software design. As a result the program was rewritten in Python in its main parts, taking advantage of simplicity of this script language and its variety of well developed software libraries, including ObsPy. SHX provides an easy access to waveforms and metadata via arclink and FDSN webservice protocols, also access to event catalogs is implemented. With single commands whole networks or stations within a certain area may be read in, the metadata are retrieved from the servers and stored in a local database. For data processing the large set of SH commands is available, as well as the SH scripting language. Via this SH language scripts or additional Python modules the command set of SHX is easily extendable. The program is open source, tested on Linux operating systems, documentation and download is found at URL "https://www.seismic-handler.org/".

  13. Spitzer IRS Spectra of Debris Disks in the Scorpius-Centaurus OB Association

    NASA Astrophysics Data System (ADS)

    Jang-Condell, Hannah; Chen, Christine H.; Mittal, Tushar; Manoj, P.; Watson, Dan; Lisse, Carey M.; Nesvold, Erika; Kuchner, Marc

    2015-08-01

    We analyze spectra obtained with the Spitzer Infrared Spectrograph (IRS) of 110 B-, A-, F-, and G-type stars with optically thin infrared excess in the Scorpius-Centaurus OB association. The ages of these stars range from 11 to 17 Myr. We fit the infrared excesses observed in these sources by Spitzer IRS and the Multiband Imaging Photometer for Spitzer (MIPS) to simple dust models according to Mie theory. We find that nearly all of the objects in our study can be fit by one or two belts of dust. Dust around lower mass stars appears to be closer in than around higher mass stars, particularly for the warm dust component in the two-belt systems, suggesting a mass-dependent evolution of debris disks around young stars. For those objects with stellar companions, all dust distances are consistent with truncation of the debris disk by the binary companion. The gaps between several of the two-belt systems can place limits on the planets that might lie between the belts, potentially constraining the mass and locations of planets that may be forming around these stars.

  14. The OB hospitalist and the risk manager: ready for prime time.

    PubMed

    Veltman, Larry

    2011-01-01

    In 1996, Wachter and Goldman described a new model of care in which hospital-based physicians provided patients' inpatient care in lieu of the patient's primary physician.(1) They termed these physicians hospitalists. The hospitalist movement had taken hold, and by 1999, 65% of internists had hospitalists in their community and 28% reported using them for inpatient care.(2) In 2003, Louis Weinstein, in an article entitled "The Laborist: A New Focus of Practice for the Obstetrician"(3) advocated for the adoption of the hospitalist model to obstetrical care. In a 2010 study, of 28,545 members of the American College of Obstetricians and Gynecologists (ACOG) contacted in a national survey, 7,044 clinicians responded, which yielded a response rate of 25%. Of the respondents, 1,020 clinicians (15% of respondents, 3.6% of the entire sample) described themselves as obstetrics/gynecology hospitalists or laborists.(4) According to the web site www.obgynhospitalist.com, there are at least 115 hospitals in the country that utilize a laborist or OB hospitalist model of care.(5).

  15. H-alpha Monitoring of the Star Field around Cygnus OB2

    NASA Astrophysics Data System (ADS)

    Clarke, Seth; Hintz, Eric G.; Joner, Michael D.

    2017-01-01

    Cygnus OB2 is a young stellar association located at RA: 20:33:12 and Dec: +41:19. Given the significant number of O and B stars, with the potential to be emission line objects, this is an ideal field to test the monitoring capabilities of the H-Alpha filters discussed by Joner & Hintz (2015). From August 2013 to July 2016 we collected 50 nights of data through narrow and wide H-alpha filters using the BYU West Mountain Observatory 0.9-m telescope with a Finger Lakes PL3041 CCD. This provided 0.62 arcsec/pixel with a field of view of 21’ on a side. Photometry was obtained from these frames using DAOPhot in order to minimize contamination from nearby stars. The index was then created by subtracting the magnitude in the wide filter from that in the narrow filter. Each night was then carefully zeropointed to allow for examination of long term variation. In total we examined 580 stars to check for variability in the H-alpha emission line. We will present our preliminary results for variations seen in a number of individual stars.

  16. Noncoeval star formation, starbursts, and the growth of supershells in Ob associations

    NASA Technical Reports Server (NTRS)

    Shull, J. Michael; Saken, Jon M.

    1995-01-01

    There is strong evidence that the epoch of massive-star formation in OB associations is spread over intervals of 10-20 Myr as a result of subclustering, continuous or sequential star formation, or delayed collapse of the most massive stars. The growth of supershells is strongly influenced by this star formation history and by mass deposition to the hot bubble interior ('radiative poisoning'). Even in cases of coeval or continuous star formation, the rising energy input from massive stars, as they evlolve off the main sequence, may be observed as a 'starburst' with peak energy deposition 3-10 times that of the late-time rate due to supernovae and an excess of Wolf-Rayet stars (WR/O ratio approximately equal 0.1). The peak in energy deposition results in faster shell growth and velocity evolution than in constant-luminosity models. At finite bubble ages, this mechanism can alter the covering factor of superbubbles in the disk by factors of 2-3 and can accelerate the dynamical effects of galactic 'superwinds.' In contrast, if sufficient matter is entrained in the hot bubble, radiative poisoning will stall its growth.

  17. FIRST ORBITAL SOLUTION FOR THE NON-THERMAL EMITTER Cyg OB2 NO. 9

    SciTech Connect

    Naze, Y.; Damerdji, Y.; Rauw, G.; Mahy, L.; Morel, T.; De Becker, M.; Kiminki, D. C.; Kobulnicky, H. A.; Eenens, P.; Barbieri, C.

    2010-08-10

    After the first detection of its binary nature, the spectroscopic monitoring of the non-thermal radio emitter Cyg OB2 No. 9 (P = 2.4 yr) has continued, doubling the number of available spectra of the star. Since the discovery paper of 2008, a second periastron passage has occurred in 2009 February. Using a variety of techniques, the radial velocities could be estimated and a first, preliminary orbital solution was derived from the He I {lambda}5876 line. The mass ratio appears close to unity and the eccentricity is large, i.e., 0.7-0.75. X-ray data from 2004 and 2007 are also analyzed in quest of peculiarities linked to binarity. The observations reveal neither large overluminosity nor strong hardness, but it must be noted that the high-energy data were taken after the periastron passage, at a time where colliding wind emission may be low. Some unusual X-ray variability is however detected, with a 10% flux decrease between 2004 and 2007. To clarify their origin and find a more obvious signature of the wind-wind collision, additional data, taken at periastron and close to it, are needed.

  18. SPITZER IRS SPECTRA OF DEBRIS DISKS IN THE SCORPIUS–CENTAURUS OB ASSOCIATION

    SciTech Connect

    Jang-Condell, Hannah; Chen, Christine H.; Mittal, Tushar; Lisse, Carey M.; Manoj, P.; Watson, Dan; Nesvold, Erika; Kuchner, Marc

    2015-08-01

    We analyze spectra obtained with the Spitzer Infrared Spectrograph (IRS) of 110 B-, A-, F-, and G-type stars with optically thin infrared excess in the Scorpius–Centaurus OB association. The ages of these stars range from 11 to 17 Myr. We fit the infrared excesses observed in these sources by Spitzer IRS and the Multiband Imaging Photometer for Spitzer (MIPS) to simple dust models according to Mie theory. We find that nearly all of the objects in our study can be fit by one or two belts of dust. Dust around lower mass stars appears to be closer in than around higher mass stars, particularly for the warm dust component in the two-belt systems, suggesting a mass-dependent evolution of debris disks around young stars. For those objects with stellar companions, all dust distances are consistent with truncation of the debris disk by the binary companion. The gaps between several of the two-belt systems can place limits on the planets that might lie between the belts, potentially constraining the mass and locations of planets that may be forming around these stars.

  19. New Low-Mass Wide Companions to Members of the Sco-Cen OB Association

    NASA Astrophysics Data System (ADS)

    Finn, Molly; Mamajek, Eric E.; Luhman, Kevin; Murphy, Simon

    2017-01-01

    We have conducted a survey for wide common proper motion companions to 512 members of the Upper Cen-Lup (UCL) and Lower Cen-Cru (LCC) subgroups of the Sco-Cen OB association using astrometry and photometry from the SPM4 catalog. Companion candidates were selected within 3 arcminutes (23 kau = 0.11 pc at d = 130 pc). We find that 12% of the Sco-Cen members have stellar companions in the separation range 3-20 kau. Optical spectra of 16 candidate companions were taken with the new COSMOS spectrograph on the Blanco 4-m telescope and the Wide Field Spectrograph on the Australian National University 2.3-m telescope. The spectroscopic survey yielded 14 M-type stars with Na I surface gravity index indicative of pre-MS status, of which half were Li-rich (along with two background giant interlopers). Seven stars in the range M1-M4.5 appear to be Li depleted, but otherwise seem to be pre-MS due to their chromospheric activity, low surface gravity via the Na I index, and their co- movement with other young stars in Sco-Cen. We suggest that these stars represent the Li depletion boundary for UCL and LCC. We acknowledge support from NSF award AST-1313029 and the REU Site in Physics and Astrophysics at the University of Rochester supported by NSF award PHY-1156339.

  20. BOREAS TE-1 CO2 and CH4 Flux Data Over the SSA-OBS Site

    NASA Technical Reports Server (NTRS)

    Anderson, Darwin; Papagno, Andrea; Hall, Forrest G. (Editor); Newcomer, Jeffrey A. (Editor)

    2000-01-01

    The BOREAS TE-1 team collected various data to characterize the soil-plant systems in the BOREAS SSA. Particular emphasis was placed on nutrient biochemistry, the stores and transfers of organic carbon, and how the characteristics were related to measured methane fluxes. The overall transect in the Prince Albert National Park (Saskatchewan, Canada) included the major plant communities and related soils that occurred in that section of the boreal forest. Soil physical, chemical, and biological measurements along the transect were used to characterize the static environment, which allowed them to be related to methane fluxes. Chamber techniques were used to provide a measure of methane production/uptake. Chamber measurements coupled with flask sampling were used to determine the seasonality of methane fluxes. This particular data set contains carbon dioxide and methane flux values from the SSA-OBS site. The data were collected from 09-Jun to 04-Sep-1994. The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  1. Central stars of planetary nebulae. II. New OB-type and emission-line stars

    NASA Astrophysics Data System (ADS)

    Weidmann, W. A.; Gamen, R.

    2011-07-01

    Context. There are more than 3000 confirmed and probably known Galactic planetary nebulae (PNe), but central star spectroscopic information is available for only 13% of them. Aims: We have undertaken a spectroscopic survey of the central stars in PNe to identify their spectral types. Methods: We performed spectroscopic observations at low resolution with the 2-m telescope at CASLEO, Argentina. Results: We present the spectra of 46 central stars of PNe, most of them are OB-type and emission-line stars. Based on data collected at the Complejo Astronómico El Leoncito (CASLEO), which is operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina y Universidades Nacionales de La Plata, Córdoba y San Juan, Argentina.The reduced spectra (FITS files) are available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/531/A172

  2. DISK EVOLUTION IN OB ASSOCIATIONS: DEEP SPITZER/IRAC OBSERVATIONS OF IC 1795

    SciTech Connect

    Roccatagliata, Veronica; Bouwman, Jeroen; Henning, Thomas; Gennaro, Mario; Sicilia-Aguilar, Aurora; Feigelson, Eric; Kim, Jinyoung Serena; Lawson, Warrick A.

    2011-06-01

    We present a deep Spitzer/Infrared Array Camera (IRAC) survey of the OB association IC 1795 carried out to investigate the evolution of protoplanetary disks in regions of massive star formation. Combining Spitzer/IRAC data with Chandra/Advanced CCD Imaging Spectrometer observations, we find 289 cluster members. An additional 340 sources with an infrared excess, but without X-ray counterpart, are classified as cluster member candidates. Both surveys are complete down to stellar masses of about 1 M{sub sun}. We present pre-main-sequence isochrones computed for the first time in the Spitzer/IRAC colors. The age of the cluster, determined via the location of the Class III sources in the [3.6]-[4.5]/[3.6] color-magnitude diagram, is in the range of 3-5 Myr. As theoretically expected, we do not find any systematic variation in the spatial distribution of disks within 0.6 pc of either O-type star in the association. However, the disk fraction in IC 1795 does depend on the stellar mass: sources with masses >2 M{sub sun} have a disk fraction of {approx}20%, while lower mass objects (2-0.8 M{sub sun}) have a disk fraction of {approx}50%. This implies that disks around massive stars have a shorter dissipation timescale.

  3. A novel scheme of signaling protocol based on mobile agent and OBS

    NASA Astrophysics Data System (ADS)

    Mao, Minjing; Liu, Deming; Li, Wei

    2005-11-01

    A novel scheme of signaling protocol based on mobile agent and OBS which runs over a core DWDM network is promoted. Design of optical wavelength channels in the scheme is to choose 1310nm band to be control optical wavelength channel to transmit BHPs and 1550nm band to be burst packets optical wavelength channels to transmit BPs. Referring to RSVP-TE in DCM ASON, significations and formats of signaling messages in the protocol are defined. The key design of scheme is to utilize the structure of active packets in the application of mobile agent MANet to encapsulate signaling messages and traffic together into one BHP to shorten the set-up time of an optical path. Such structure is also used to process distributed disposals to alleviate the workload of one node in the network to promote cooperating calculation ability of each node in the network. The communication between a source node and a destination node through one or multiple intermediate nodes is presented as an example to describe the processing procedures of the protocol. The scheme is implemented in a wavelength router, which is briefly introduced.

  4. THE GALACTIC SPATIAL DISTRIBUTION OF OB ASSOCIATIONS AND THEIR SURROUNDING SUPERNOVA-GENERATED SUPERBUBBLES

    SciTech Connect

    Higdon, J. C.; Lingenfelter, R. E. E-mail: rlingenfelter@ucsd.edu

    2013-10-01

    The Galactic spatial distribution of OB associations and their surrounding superbubbles (SBs) reflect the distribution of a wide range of important processes in our Galaxy. In particular, it can provide a three-dimensional measure not only of the major source distribution of Galactic cosmic rays, but also the Galactic star formation distribution, the Lyman continuum ionizing radiation distribution, the core-collapse supernova distribution, the neutron star and stellar black hole production distribution, and the principal source distribution of freshly synthesized elements. Thus, we construct a three-dimensional spatial model of the massive-star distribution based primarily on the emission of the H II envelopes that surround the giant SBs and are maintained by the ionizing radiation of the embedded O stars. The Galactic longitudinal distribution of the 205 μm N II radiation, emitted by these H II envelopes, is used to infer the spatial distribution of SBs. We find that the Galactic SB distribution is dominated by the contribution of massive-star clusters residing in the spiral arms.

  5. Isolation and Purification of Cu-free Methanobactin from Methylosinus trichosporium OB3b

    SciTech Connect

    M Pesch; I Christl; K Barmettler; S Kraemer; R Kretzschmar

    2011-12-31

    The isolation of highly pure copper-free methanobactin is a prerequisite for the investigation of the biogeochemical functions of this chalkophore molecule produced by methane oxidizing bacteria. Here, we report a purification method for methanobactin from Methylosinus trichosporium OB3b cultures based on reversed-phase HPLC fractionation used in combination with a previously reported resin extraction. HPLC eluent fractions of the resin extracted product were collected and characterized with UV-vis, FT-IR, and C-1s NEXAFS spectroscopy, as well as with elemental analysis and ESI-MS. The results showed that numerous compounds other than methanobactin were present in the isolate obtained with resin extraction. Molar C/N ratios, mass spectrometry measurements, and UV-vis spectra indicated that methanobactin was only present in one of the HPLC fractions. On a mass basis, methanobactin carbon contributed only 32% to the total organic carbon isolated with resin extraction. Our spectroscopic results implied that besides methanobactin, the organic compounds in the resin extract comprised breakdown products of methanobactin as well as polysaccharide-like substances. Our results demonstrate that a purification step is indispensable in addition to resin extraction in order to obtain pure methanobactin. The proposed HPLC purification procedure is suitable for semi-preparative work and provides copper-free methanobactin.

  6. VizieR Online Data Catalog: Northern Galactic OB stars vsini (Simon-Diaz+, 2014)

    NASA Astrophysics Data System (ADS)

    Simon-Diaz, S.; Herrero, A.

    2014-04-01

    The spectroscopic observations considered for this study are part of the IACOB spectroscopic database of northern Galactic OB stars (last described in Simon-Diaz et al., 2011, Bull. Soc. Roy. Sci. Liege, 80, 514 and Stellar Clusters and Associations: Proc. A RIA Workshop on Gaia, eds. E. J. Alfaro Navarro, A. T. Gallego Calvente, & M. R. Zapatero Osorio, 255). This unique high-quality spectroscopic database has been compiled in the framework of the IACOB project. To date, the IACOB database comprises 1250 spectra of 153 and 97 Galactic O- and early B-type stars, respectively, observable from the Roque de los Muchachos observatory in La Palma (Spain). The spectra have a resolving power of 46000 and 23000, a typical signal-to-noise ratio (S/N) above 150, and were compiled between November 2008 and January 2013 with the high-resolution FIbre-fed Echelle Spectrograph (FIES) attached to the Nordic Optical Telescope (NOT). The IACOB database has a multi-epoch character that enables investigations of the binary/multiple nature of considered stars and the temporal variations in individual objects with at least three spectra per observed target. In this study, we only used a subsample of the spectra, discarding all stars with signatures of multiplicity (which means that we only considered apparently single and SB1 stars), and only considering the spectrum with the highest S/N ratio per star. (5 data files).

  7. The structure of KPN03535 (gi|152972051), a novel putative lipoprotein from Klebsiella pneumoniae, reveals an OB-fold

    PubMed Central

    Das, Debanu; Kozbial, Piotr; Han, Gye Won; Carlton, Dennis; Jaroszewski, Lukasz; Abdubek, Polat; Astakhova, Tamara; Axelrod, Herbert L.; Bakolitsa, Constantina; Chen, Connie; Chiu, Hsiu-Ju; Chiu, Michelle; Clayton, Thomas; Deller, Marc C.; Duan, Lian; Ellrott, Kyle; Elsliger, Marc-André; Ernst, Dustin; Farr, Carol L.; Feuerhelm, Julie; Grzechnik, Anna; Grant, Joanna C.; Jin, Kevin K.; Johnson, Hope A.; Klock, Heath E.; Knuth, Mark W.; Krishna, S. Sri; Kumar, Abhinav; Marciano, David; McMullan, Daniel; Miller, Mitchell D.; Morse, Andrew T.; Nigoghossian, Edward; Nopakun, Amanda; Okach, Linda; Oommachen, Silvya; Paulsen, Jessica; Puckett, Christina; Reyes, Ron; Rife, Christopher L.; Sefcovic, Natasha; Tien, Henry J.; Trame, Christine B.; van den Bedem, Henry; Weekes, Dana; Wooten, Tiffany; Xu, Qingping; Hodgson, Keith O.; Wooley, John; Deacon, Ashley M.; Godzik, Adam; Lesley, Scott A.; Wilson, Ian A.

    2010-01-01

    KPN03535 (gi|152972051) is a putative lipoprotein of unknown function that is secreted by Klebsiella pneumoniae MGH 78578. The crystal structure reveals that despite a lack of any detectable sequence similarity to known structures, it is a novel variant of the OB-fold and structurally similar to the bacterial Cpx-pathway protein NlpE, single-stranded DNA-binding (SSB) proteins and toxins. K. pneumoniae MGH 78578 forms part of the normal human skin, mouth and gut flora and is an opportunistic pathogen that is linked to about 8% of all hospital-acquired infections in the USA. This structure provides the foundation for further investigations into this divergent member of the OB-fold family. PMID:20944219

  8. Suspended-sediment and fresh-water discharges in the Ob and Yenisey rivers, 1960-1988

    USGS Publications Warehouse

    Meade, R.H.; Bobrovitskaya, N.N.; Babkin, V.I.

    2000-01-01

    Of the world's great rivers, the Ob and Yenisey rank among the largest suppliers of fresh water and among the smallest suppliers of suspended sediment to the coastal ocean. Sediment in the middle reaches of the rivers is mobilized from bordering terraces and exchanged between channels and flood plains. Sediment in the lower reaches of these great rivers is deposited and stored (permanently, on a millennial time scale) in flood plains. Sediment discharges, already small under natural conditions, are diminished further by large manmade reservoirs that trap significant proportions of the moving solids. The long winter freeze and sudden spring breakup impose a peakedness in seasonal water runoff and sediment discharge that contrasts markedly with that in rivers of the tropics and more temperate climates. Very little sediment from the Ob and Yenisey rivers is being transported to the open waters of the Arctic Ocean under present conditions.

  9. Effects of dopamine on leptin release and leptin gene (OB) expression in adipocytes from obese and hypertensive patients

    PubMed Central

    Alvarez-Aguilar, Cleto; Alvarez-Paredes, Alfonso Rafael; Lindholm, Bengt; Stenvinkel, Peter; García-López, Elvia; Mejía-Rodríguez, Oliva; López-Meza, Joel Edmundo; Amato, Dante; Paniagua, Ramon

    2013-01-01

    Background A reduction of dopaminergic (DAergic) activity with increased prolactin levels has been found in obese and hypertensive patients, suggesting its involvement as a pathophysiological mechanism promoting hypertension. Similarly, leptin action increasing sympathetic activity has been proposed to be involved in mechanisms of hypertension. The aim of this study was to analyze the effects of DA, norepinephrine (NE), and prolactin on leptin release and leptin gene (OB) expression in adipocytes from obese and hypertensive patients. Methods Leptin release and OB gene expression were analyzed in cultured adipocytes from 16 obese and hypertensive patients treated with DA (0.001, 0.01, 0.1, and 1.0 μmol/L), NE (1.0 μmol/L), insulin (0.1 μmol/L), and prolactin (1.0 μmol/L), and from five nonobese and normotensive controls treated with DA (1 μmol/L), NE (1 μmol/L), insulin (0.1 μmol/L), and prolactin (1.0 μmol/L). Results A dose-related reduction of leptin release and OB gene messenger ribonucleic acid expression under different doses of DA was observed in adipocytes from obese hypertensive patients. Whereas prolactin treatment elicited a significant increase of both leptin release and OB gene expression, NE reduced these parameters. Although similar effects of DA and NE were observed in adipocytes from controls, baseline values in controls were reduced to 20% of the value in adipocytes from obese hypertensive patients. Conclusion These results suggest that DAergic deficiency contributes to metabolic disorders linked to hyperleptinemia in obese and hypertensive patients. PMID:24348062

  10. Leptin Receptor (Ob-R) expression in the ovary and uterus of the wild japanese black bear (Ursus thibetanus japonicus).

    PubMed

    Nakamura, Sachiko; Nishii, Naohito; Yamanaka, Atsushi; Kitagawa, Hitoshi; Asano, Makoto; Tsubota, Toshio; Suzuki, Masatsugu

    2009-04-01

    To verify target organ(s) of leptin in the reproductive system of the Japanese black bear, we examined the expression of leptin receptor (Ob-R) protein in ovaries and uteri collected from July to December 2006 by immunohistochemical techniques. Eleven of 22 female Japanese black bears examined had corpora lutea (CLs) in their ovaries and were thought to have undergone or to have terminated delayed implantation in the early pregnancy stage. The CLs were classified into 3 types based on morphological features. The maximum diameters of Type 1 CLs ranged 3 to 7 mm, and the luteal cells contained numerous vacuoles in the cytoplasm, which suggests that this type of CL was functional. The maximum diameters of Type 2 CLs were approximately 7 mm, and the luteal cells contained fewer vacuoles in the cytoplasm, which suggests that this type of CL was in the early stage of regression. Finally, the maximum diameters of Type 3 CLs were approximately 1 mm, and these CLs contained collagen fibers among their luteal cells, which suggests that this type of CL had regressed. The 3 types of CLs showed different reactions to Ob-R, with positive staining in Type 1, much less positive staining in Type 2 and nearly negative staining in Type 3. In bears having CLs with functional and regressive features (Type 1 and 2 CLs), Ob-R was also immunolocalized in the developed glandular and ductal endometrial epithelium. In contrast, the Ob-R was absent in the undeveloped endometrial epithelium in bears with regressed (Type 3 CLs) or no CLs. These findings suggested that leptin directly targets CLs and the endometrium so as to develop and maintain them during the delayed implantation period in Japanese black bears.

  11. Inverse-Ray Imaging of Gas Hydrates Along a MCS/OBS Profile at the Continental Slope Offshore SW Taiwan

    NASA Astrophysics Data System (ADS)

    Wang, T. K.; Chen, C.; Yang, B.; Lee, C.

    2006-12-01

    Prevalence of gas hydrates offshore SW Taiwan has been proposed due to lots of bottom-simulated reflectors (BSR) appeared on the seismic data. In this paper, we analyze a MCS/OBS profile with intensive BSR signals at the continental slope of the northern South China Sea. Firstly, MCS data with 160 channels collected by R/V Maurice-Ewing in September 1995 is re-processed through vertical velocity analysis, horizon velocity analysis, and prestack depth migration. Then, OBS data collected by the first Micro-OBS survey from NTOU team in August 2005 is analyzed through travel-time inversion of reflected and refracted arrivals for which the initial model is constructed from the MCS result. Finally, a novel technique of inverse reflected rays by considering both MCS and OBS data is applied for layer-stripping imaging of sedimentary layers. Velocity models imaged from three methods are confirmed the prevalence of BSR at 100-400 m depth below the sea floor along the whole profile. Relatively smooth sedimentary layers are observed below the lower slope of the continent whereas several mud diapers are imaged below the upper slope of the continent. Above the mud diapers, we find gas hydrates with high velocity of about 1.9-2.1 km/s and thickness of about 100 m immediately above the strong BSR. Similarly, near the mud diapers, free gas with low velocity of about 1.4-1.7 km/s and thickness of about 200 m is imaged. Migration of free gas through diapirism may result in lots of gas hydrates accumulated below the upper slope of the continent offshore SW Taiwan.

  12. Triggering Risk Factors of the Burnout Syndrome in Ob/Gyn Physicians from a Reference Public University of Brazil

    PubMed Central

    Ferreira Bortoletti, Fátima; Teresa Benevides-Pereira, Ana Maria; Vasconcellos, Esdras Guerreiro; Siqueira, José Oliveira; Araujo Júnior, Edward; Nardozza, Luciano Marcondes Machado; Sebastiani, Ricardo Werner; Moron, Antonio Fernandes

    2012-01-01

    Objective. To identify the risk factors to the development of Burnout Syndrome in Ob/Gyn Brazilian physicians in four dimensions: emotional exhaustion (EE), professional repression (PR), dehumanization (De), and emotional distancing (EmD). Methods. A prospective cross-sectional study was realized with 48 Ob/Gyn physicians (12 lecturers, 12 attending physicians, 12 medical residents, and 12 graduate students) from Department of Obstetrics, São Paulo Federal University (UNIFESP). We used a sociodemographic questionnaire focusing on the activities (administrative, educational, healthcare, and research). We applied a Burnout Syndrome Inventory (BSI) composed of two parts: triggering factors (ISB1) and the Burnout Syndrome (ISB2). The ISB1 is composed of two scales: positive organizational conditions (POC) and negative organizational conditions (NOC). The ISB2 is composed of four scales: EE, PR, De, and EmD. Results. We observed a rate below and above average to POC and NOC, respectively. The dimensions recorded a level above average to EE, an index at the upper limit of the average to De, a median index to EmD, and a median index to PR. Conclusions. The Ob/Gyn physicians are in an area of vulnerability for the development of Burnout Syndrome due to the high level of EE and De, associated with a median index of PR. The high rate of NOC contributes to the triggering of this scenery. PMID:23304541

  13. Comparison of AMSR-E and SSM/I snow parameter retrievals over the Ob river basin

    USGS Publications Warehouse

    Mognard, N.M.; Grippa, M.; LeToan, T.; Kelly, R.E.J.; Chang, A.T.C.; Josberger, E.G.

    2004-01-01

    Passive microwave observations from the Advanced Microwave Scanning Radiometer - EOS (AMSR-E) and from the Special Sensor Microwave Imager (SSM/I) are used to analyse the evolution of the snow pack in the Ob river basin during the snow season of 2002-03. The Ob river is the biggest Russian river with respect to its watershed area (2 975 000 km2). The Ob originates in the Altai mountains and flows northward across the vast West Siberian lowland towards the Arctic Ocean. The majority of snow cover is contained in the lowlands rather than in mountainous regions and persists for six months or more. During the snow season, surface air temperatures are very cold. Therefore, the combination of cold dry snow and large areas of uniform topography is ideal for snowpack extent and water equivalent retrievals from passive microwave observations. The thermal gradient through the snow pack is estimated and used to model the growth of the snow grain size and to compute the evolution of the passive microwave derived snow depth over the region. A comparison between the AMSR-E and SSM/I estimates is performed and the differences between the snow parameters from the two satellite instruments are analysed.

  14. Receiver functions using OBS data: promises and limitations from numerical modelling and examples from the Cascadia Initiative

    NASA Astrophysics Data System (ADS)

    Audet, Pascal

    2016-06-01

    The expanding fleet of broad-band ocean-bottom seismograph (OBS) stations is facilitating the study of the structure and seismicity of oceanic plates at regional scales. For continental studies, an important tool to characterize continental crust and mantle structure is the analysis of teleseismic P receiver functions. In the oceans, however, receiver functions potentially suffer from several limiting factors that are unique to ocean sites and plate structures. In this study, we model receiver functions for a variety of oceanic lithospheric structures to investigate the possibilities and limitations of receiver functions using OBS data. Several potentially contaminating effects are examined, including pressure reverberations from the water column for various ocean-floor depths and the effects of a layer of low-velocity marine sediments. These modelling results indicate that receiver functions from OBS data are difficult to interpret in the presence of marine sediments, but shallow-water sites in subduction zone forearcs may be suitable for constraining various crustal elements around the locked megathrust fault. We propose using a complementary approach based on transfer function modelling combined with a grid search approach that bypasses receiver functions altogether and estimates model properties directly from minimally processed waveforms. Using real data examples from the Cascadia Initiative, we show how receiver and transfer functions can be used to infer seismic properties of the oceanic plate in both shallow (Cascadia forearc) and deep (Juan de Fuca Ridge) ocean settings.

  15. Phytoplankton succession in the Ob-Yenisei Shallow zone of the Kara Sea based on Russian databases

    NASA Astrophysics Data System (ADS)

    Makarevich, P. R.; Larionov, V. V.; Moiseev, D. V.

    2015-07-01

    Here, data about the taxonomic composition and spatial distribution of planktonic microalgae in the Ob Bay and the southern Kara Sea in north Russia were analyzed during all hydrological seasons over 11 years (1996-2006). Data were obtained through detailed in situ observations. These data are part of our arctic phytoplankton database. Phytoplankton inhabiting the near shore continental area of the Kara Sea exhibited four phases in the annual succession cycle: a prevernal phase (cryoflora bloom), a vernal phase (ice-edge bloom), a summer-fall phase (mixed synthesis phase), and a winter phase (dormant phase). These phases were clearly differentiated based on the composition of dominant phytoplankton species complexes and quantitative characteristics (i.e., microalgal number and biomass). In the study region, which is completely covered by ice for most of the year (from October to June), the process of primary production begins at the same time as in ice-free coastal areas. Sub-ice blooming and growth of cryoflora initiate beneath the ice cover, long before it breaks down. In addition, from July to October, high phytoplankton biomass was recorded in Ob Bay and in areas adjacent to the Ob-Yenisei shallows. This information provides quantitative evidence for the higher productivity of waters off the Obestuary, compared to other coastal areas in the Kara Sea. The main factor responsible for this phenomenon is the permanent (during the warm season) transport of living and dead organic matter by river runoff to shelf waters.

  16. An anomalous extinction law in the Cep OB3b young cluster: Evidence for dust processing during gas dispersal

    SciTech Connect

    Allen, Thomas S.; Prchlik, Jakub J.; Megeath, S. Thomas; Gutermuth, Robert A.; Pipher, Judith L.; Naylor, Tim; Jeffries, R. D.

    2014-05-10

    We determine the extinction law through Cep OB3b, a young cluster of 3000 stars undergoing gas dispersal. The extinction is measured toward 76 background K giants identified with MMT/Hectospec spectra. Color excess ratios were determined toward each of the giants using V and R photometry from the literature, g, r, i, and z photometry from the Sloan Digital Sky Survey and J, H, and K{sub s} photometry from the Two Micron All Sky Survey. These color excess ratios were then used to construct the extinction law through the dusty material associated with Cep OB3b. The extinction law through Cep OB3b is intermediate between the R{sub V} = 3.1 and R{sub V} = 5 laws commonly used for the diffuse atomic interstellar medium and dense molecular clouds, respectively. The dependence of the extinction law on line-of-sight A{sub V} is investigated and we find the extinction law becomes shallower for regions with A{sub V} > 2.5 mag. We speculate that the intermediate dust law results from dust processing during the dispersal of the molecular cloud by the cluster.

  17. OB-fold domain of KREPA4 mediates high-affinity interaction with guide RNA and possesses annealing activity.

    PubMed

    Kala, Smriti; Salavati, Reza

    2010-10-01

    KREPA4, also called MP24, is an essential mitochondrial guide RNA (gRNA)-binding protein with a preference for the 3' oligo(U) tail in trypanosomes. Structural prediction and compositional analysis of KREPA4 have identified a conserved OB (oligonucleotide/oligosaccharide-binding)-fold at the C-terminal end and two low compositional complexity regions (LCRs) at its N terminus. Concurrent with these predictions, one or both of these regions in KREPA4 protein may be involved in gRNA binding. To test this possibility, deletion mutants of KREPA4 were made and the effects on the gRNA-binding affinities were measured by quantitative electrophoretic mobility shift assays. The gRNA-binding specificities of these mutants were evaluated by competition experiments using gRNAs with U-tail deletions or stem-loop modifications and uridylated nonguide RNAs or heterologous RNA. Our results identified the predicted OB-fold as the functional domain of KREPA4 that mediates a high-affinity interaction with the gRNA oligo(U) tail. An additional contribution toward RNA-binding function was localized to LCRs that further stabilize the binding through sequence-specific interactions with the guide secondary structure. In this study we also found that the predicted OB-fold has an RNA annealing activity, representing the first report of such activity for a core component of the RNA editing complex.

  18. Triggering risk factors of the burnout syndrome in OB/GYN physicians from a reference public university of Brazil.

    PubMed

    Ferreira Bortoletti, Fátima; Teresa Benevides-Pereira, Ana Maria; Vasconcellos, Esdras Guerreiro; Siqueira, José Oliveira; Araujo Júnior, Edward; Nardozza, Luciano Marcondes Machado; Sebastiani, Ricardo Werner; Moron, Antonio Fernandes

    2012-01-01

    Objective. To identify the risk factors to the development of Burnout Syndrome in Ob/Gyn Brazilian physicians in four dimensions: emotional exhaustion (EE), professional repression (PR), dehumanization (De), and emotional distancing (EmD). Methods. A prospective cross-sectional study was realized with 48 Ob/Gyn physicians (12 lecturers, 12 attending physicians, 12 medical residents, and 12 graduate students) from Department of Obstetrics, São Paulo Federal University (UNIFESP). We used a sociodemographic questionnaire focusing on the activities (administrative, educational, healthcare, and research). We applied a Burnout Syndrome Inventory (BSI) composed of two parts: triggering factors (ISB1) and the Burnout Syndrome (ISB2). The ISB1 is composed of two scales: positive organizational conditions (POC) and negative organizational conditions (NOC). The ISB2 is composed of four scales: EE, PR, De, and EmD. Results. We observed a rate below and above average to POC and NOC, respectively. The dimensions recorded a level above average to EE, an index at the upper limit of the average to De, a median index to EmD, and a median index to PR. Conclusions. The Ob/Gyn physicians are in an area of vulnerability for the development of Burnout Syndrome due to the high level of EE and De, associated with a median index of PR. The high rate of NOC contributes to the triggering of this scenery.

  19. Fundamental parameters of Galactic luminous OB stars. IV. The upper HR diagram

    NASA Astrophysics Data System (ADS)

    Herrero, A.; Puls, J.; Villamariz, M. R.

    2000-02-01

    H_alpha ,is also affected. Some stars of our sample have such high mass-loss rates that the derivation of gravities from the wings of Balmer lines, in particular H_{\\log gamma}, becomes doubtful. For the most extreme objects, the mass-loss rates needed to fit H_alpha are different from those needed to fit H_{\\log gamma}, by a maximum factor of two. From the point of view of individual stars, we have analysed some of the most massive and luminous stars in the Milky Way. According to our analysis, three of them (Cyg OB2 #7, HD 15 570 and HD 15 558) have particularly large initial masses, close to or in excess of 100 M/Msunsun. Finally, the least luminous object in our sample, HD 5 689, could have been erroneously assigned to Cas OB7 and might be a runaway star. The INT is operated on the island of La Palma by the RGO in the Spanish Obervatorio de El Roque de los Muchachos of the Instituto de Astrof\\'\\i sica de Canarias.

  20. Interstellar CaII line intensities and the distances of the OB stars

    NASA Astrophysics Data System (ADS)

    Krełowski, J.; Galazutdinov, G. A.; Megier, A.; Strobel, A.; Bondar, A.; Musaev, F. A.; Han, I.

    We show that the equivalent widths of the well-known interstellar CaII H and K lines can be used to determine the distances to OB stars in our Galaxy. The equivalent widths, measured in the spectra of 149 early-type stars, exhibit a simple (approximately inverse) relation with Hipparcos parallaxes. It was Struve (1928) who first observed the relation between the "detached" CaII K line and estimated distance. Further work on the subject was published by Sanford (1937), Merrill (1937), Evans (1941), and Beals and Oke (1953). While many later studies have used the CaII (and other atomic) lines to study both spatial and velocity structure of the interstellar medium, the early results on the intensity × distance relation were for nearly half a century difficult to improve on, because of the problems associated with estimating stellar distances in the appropriate distance range (hundreds of parsecs). The publication of the Hipparcos Catalogue (ESA 1997) made available a set of parallaxes for 120 thousand stars measured with miliarcsecond accuracy. Using this homogeneous source of parallax data, and a collection of high resolution spectra of 149 OB stars, we investigate the dependence of the equivalent widths of CaII H and K interstellar lines on parallax. For many stars in our sample, the errors in Hipparcos parallaxes are comparable to the parallaxes themselves. We studied the relations directly in the parallax × equivalent width diagrams, avoiding problems (e.g truncation bias) associated with the inversion (Arenou & Luri 1999, Smith 2003). We have selected for this project a set of 149 early-type stars (no later than B3), where the influence of possible stellar contamination of H and K lines is negligible. The spectra have been collected using echelle spectrographs of several observatories: MAESTRO (Terskol, Northern Caucasus), Feros (ESO) and BOES (Korea). The spectral resolution varies between 30,000 and 120,000. Figure 1 presents the parallax vs EW(CaII H

  1. Erratum: ``Post-T Tauri Stars in the Nearest OB Association'' (AJ, 124, 1670 [2002])

    NASA Astrophysics Data System (ADS)

    Mamajek, Eric E.; Meyer, Michael R.; Liebert, James

    2006-04-01

    In Table 3 the F6 V-type spectral standard star HR 7061 is mistakenly aliased as HD 173677 but should be HD 173667. In §7.2 HIP 68282 is mistakenly aliased as ν1 Cen (``nu 1'') but should be υ1 Cen (``upsilon 1'') according to the Bright Star Catalog (D. Hoffleit & W. H. Warren, Jr. [New Haven: Yale Univ. Obs.; 1991]). The same error in SIMBAD has since been corrected. In Appendix A, third paragraph, the units of slope should be K [log(cm s-2)]-1, not K [log(cm s-1)]-1. In Appendix C there is an incorrect sign in the second term in equation (C6), and incorrect color ranges were published for equations (C6) and (C7). Equations (C6) and (C7) provide polynomial transformations between the Tycho (BT-VT) and Cousins-Johnson (B-V) colors. The correct equation (C6), applicable over the color range (BT-VT)∈[0.40, 2.00], isB-V=(BT-VT)-7.813×10-3(BT-VT)-1.489×10-1(BT-VT)2+3.384×10-2(BT-VT)3. (C6)The correct formula (C6) was applied in the paper but transcribed incorrectly to the manuscript. Equation (C7) was published correctly, but the published color range is incorrect. For the color range (BT-VT)∈[-0.25, 0.40], equation (C7) should be used (same as published):B-V=(BT-VT)-0.006-1.069×10-1(BT-VT)+1.459×10-1(BT-VT)2. (C7)We thank John Carpenter for bringing the error in equation (C6) to our attention and François Bonnarel and Christian Nitschelm for pointing out the stellar misidentifications.

  2. ALMA Observations of Circumstellar Disks in the Upper Scorpius OB Association

    NASA Astrophysics Data System (ADS)

    Barenfeld, Scott A.; Carpenter, John M.; Ricci, Luca; Isella, Andrea

    2016-08-01

    We present ALMA observations of 106 G-, K-, and M-type stars in the Upper Scorpius OB Association hosting circumstellar disks. With these data, we measure the 0.88 mm continuum and 12CO J = 3-2 line fluxes of disks around low-mass (0.14-1.66 M ⊙) stars at an age of 5-11 Myr. Of the 75 primordial disks in the sample, 53 are detected in the dust continuum and 26 in CO. Of the 31 disks classified as debris/evolved transitional disks, five are detected in the continuum and none in CO. The lack of CO emission in approximately half of the disks with detected continuum emission can be explained if CO is optically thick but has a compact emitting area (≲40 au), or if the CO is heavily depleted by a factor of at least ˜1000 relative to interstellar medium abundances and is optically thin. The continuum measurements are used to estimate the dust mass of the disks. We find a correlation between disk dust mass and stellar host mass consistent with a power-law relation of {M}{dust}\\propto {M}* 1.67+/- 0.37. Disk dust masses in Upper Sco are compared to those measured in the younger Taurus star-forming region to constrain the evolution of disk dust mass. We find that the difference in the mean of {log}({M}{dust}/{M}* ) between Taurus and Upper Sco is 0.64 ± 0.09, such that M dust/M * is lower in Upper Sco by a factor of ˜4.5.

  3. Seismic velocity variation along the Izu-Bonin arc estaimated from traveltime tomography using OBS data

    NASA Astrophysics Data System (ADS)

    Obana, K.; Tamura, Y.; Takahashi, T.; Kodaira, S.

    2014-12-01

    The Izu-Bonin (Ogasawara) arc is an intra-oceanic island arc along the convergent plate boundary between the subducting Pacific and overriding Philippine Sea plates. Recent active seismic studies in the Izu-Bonin arc reveal significant along-arc variations in crustal structure [Kodaira et al., 2007]. The thickness of the arc crust shows a remarkable change between thicker Izu (~30 km) and thinner Bonin (~10 km) arcs. In addition to this, several geological and geophysical contrasts, such as seafloor topography and chemical composition of volcanic rocks, between Izu and Bonin arc have been reported [e.g., Yuasa 1992]. We have conducted earthquake observations using ocean bottom seismographs (OBSs) to reveal seismic velocity structure of the crust and mantle wedge in the Izu-Bonin arc and to investigate origin of the along-arc structure variations. We deployed 40 short-period OBSs in Izu and Bonin area in 2006 and 2009, respectively. The OBS data were processed with seismic data recorded at routine seismic stations on Hachijo-jima, Aoga-shima, and Chichi-jima operated by National Research Institute for Earth Science and Disaster Prevention (NIED). More than 5000 earthquakes were observed during about three-months observation period in each experiment. We conducted three-dimensional seismic tomography using manually picked P- and S-wave arrival time data. The obtained image shows a different seismic velocity structures in the mantle beneath the volcanic front between Izu and Bonin arcs. Low P-wave velocity anomalies in the mantle beneath the volcanic front in the Izu arc are limited at depths deeper than those in the Bonin arc. On the other hand, P-wave velocity in the low velocity anomalies beneath volcanic front in the Bonin arc is slower than that in the Izu arc. These large-scale along-arc structure variations in the mantle could relate to the geological and geophysical contrasts between Izu and Bonin arcs.

  4. The History of Low-Mass Star Formation in the Upper Scorpius OB Association

    NASA Astrophysics Data System (ADS)

    Preibisch, Thomas; Zinnecker, Hans

    1999-05-01

    We use a large sample of about 100 low-mass pre-main-sequence (PMS) stars in the Upper Scorpius OB association to explore the star formation history and the initial mass function of this association. Upper Scorpius is an ideal target for such a study, because the star formation process there is finished. The PMS stars have recently been found in a spatially unbiased wide-field survey of X-ray-selected stars in a 160 deg^2 area, covering the Upper Scorpius association nearly completely. Following the optical characterization of these PMS stars, we present a new HR diagram for this association. We perform a detailed analysis of the HR diagram, taking proper account of the uncertainties and the effects of unresolved binaries, and derive ages and masses for the PMS stars. We find that the low-mass PMS stars have a mean age of about 5 Myr and show no evidence for a large age dispersion. This agrees very well with the age of 5-6 Myr previously found for the massive stars and shows that low-mass and high-mass stars are coeval and cospatial and thus have formed together. We conclude that the star formation process in Upper Scorpius was probably triggered by the shock wave of a supernova explosion in the nearby Upper Centaurus-Lupus association. After a short burst of very high star formation activity, which lasted only for a few Myr, star formation in Upper Scorpius was halted, probably by the strong winds and the ionizing radiation of the numerous massive stars that dispersed the molecular cloud.

  5. Spatial distribution and feeding of dominant zooplankton species in the Ob River estuary

    NASA Astrophysics Data System (ADS)

    Drits, A. V.; Nikishina, A. B.; Semenova, T. N.; Sergeeva, V. M.; Solovyev, K. A.; Flint, M. V.

    2016-05-01

    The distribution and feeding of dominant mesozooplankton species were studied in the estuary of the Ob River and adjacent inner Kara Sea shelf waters in September 2013. It was shown that the spatial distributions of Cyclops sp., Senecella siberica, Limnocalanus macrurus, Mysis oculata, Drepanopus bungei, Jashnovia tolli and Pseudocalanus sp. are related to the specific characteristics of the hydrographic regime in the estuarine frontal zone. The distributions of Cyclops sp., Senecella siberica, and Pseudocalanus sp. are mainly limited by salinity, while other species inhabit an area with a wide range of salinity values without clear preferences. Peaks of their abundance could be either consolidated or distanced in space. The populations of Jashnovia tolli, Drepanopus bungei, and Pseudocalanus sp. permanently inhabit the layer under the pycnohalocline; the populations of Cyclops sp. and Mysis oculata inhabit the upper mixed layer. Limnocalanus macrurus demonstrates a different vertical distribution pattern: the copepod undertakes diel vertical migrations in the southern part of the estuarine frontal zone; in its northern part, the population is concentrated below the pycnocline during day and night. The differences in the distributions of the studied species determine their feeding behavior and their role in phytoplankton grazing. The most intense utilization of biomass and production of autotrophic phytoplankton by zooplankton occur in the freshened water zone and the adjacent southern periphery of the estuarine frontal zone: the total daily phytoplankton consumption makes up 10-18% of the biomass and 60-380% of primary production. Daily zooplankton consumption of phytoplankton in the estuarine frontal zone decreases to 2-7% of the biomass and to 14% of primary production; in inner shelf waters, the values do not exceed 1% for both phytoplankton biomass and production.

  6. CARINA OB STARS: X-RAY SIGNATURES OF WIND SHOCKS AND MAGNETIC FIELDS

    SciTech Connect

    Gagne, Marc; Fehon, Garrett; Savoy, Michael R.; Cohen, David H.; Townsley, Leisa K.; Broos, Patrick S.; Povich, Matthew S.; Corcoran, Michael F.; Remage Evans, Nancy; Moffat, Anthony F. J.; Naze, Yael; Oskinova, Lida M.

    2011-05-01

    The Chandra Carina Complex contains 200 known O- and B-type stars. The Chandra survey detected 68 of the 70 O stars and 61 of 127 known B0-B3 stars. We have assembled a publicly available optical/X-ray database to identify OB stars that depart from the canonical L{sub X}/L{sub bol} relation or whose average X-ray temperatures exceed 1 keV. Among the single O stars with high kT we identify two candidate magnetically confined wind shock sources: Tr16-22, O8.5 V, and LS 1865, O8.5 V((f)). The O4 III(fc) star HD 93250 exhibits strong, hard, variable X-rays, suggesting that it may be a massive binary with a period of >30 days. The visual O2 If* binary HD 93129A shows soft 0.6 keV and hard 1.9 keV emission components, suggesting embedded wind shocks close to the O2 If* Aa primary and colliding wind shocks between Aa and Ab. Of the 11 known O-type spectroscopic binaries, the long orbital-period systems HD 93343, HD 93403, and QZ Car have higher shock temperatures than short-period systems such as HD 93205 and FO 15. Although the X-rays from most B stars may be produced in the coronae of unseen, low-mass pre-main-sequence companions, a dozen B stars with high L{sub X} cannot be explained by a distribution of unseen companions. One of these, SS73 24 in the Treasure Chest cluster, is a new candidate Herbig Be star.

  7. Discovering Massive Runaway Stars with Infrared Bow Shock Nebulae: Four OB Stars Found in WISE

    NASA Astrophysics Data System (ADS)

    Wernke, Heather N.; Kobulnicky, Henry A.; Dale, Daniel A.; Povich, Matthew S.; Andrews, Julian E.; Chick, William T.; Munari, Stephan; Olivier, Grace M.; Schurhammer, Danielle; Sorber, Rebecca L.

    2016-01-01

    Supernovae, pulsars, and gamma-ray bursts are examples of the result of the death of massive (late-O and early-B type) stars. Determining stellar mass loss rates can help us predict the type of death the star will endure. We focus on stars that are located at the center of an infrared bow shock nebula, indicating that the star was flung from its birthplace at supersonic speed. Observing these massive, high-velocity, runaway stars with bow shock nebulae to determine their spectral type will help in the measurements of their stellar mass loss rates. The spectra of four OB stars driving bow shock candidates are presented. These four candidates were found by searching through the Wide-field Infrared Survey Explorer (WISE) All-Sky Data Release and were the most visible in the WISE 21µm band. The spectrum for each star was obtained with the Longslit Spectrograph at the Wyoming Infrared Observatory (WIRO). The spectral types of G077.3617+01.16 (HD 229159), G079.8219+00.096 ([CPR2002]A10), G092.7265+00.18, and G076.0752-02.2044 (TYC 2697-1046-1) were found to be B1.0I, O9.0V, B0.0V, and B0.0V respectively. As predicted, the candidates are all either late-O or early-B type stars. Now that the spectral types of these stars are known, further analysis can be done to determine the velocities, temperatures, masses, and stellar mass loss rates.This work is supported by the National Science Foundation under grants AST-1063146 (REU), AST-1411851 (RUI), and AST-1412845.

  8. THE INITIAL MASS FUNCTION OF FIELD OB STARS IN THE SMALL MAGELLANIC CLOUD

    SciTech Connect

    Lamb, J. B.; Oey, M. S.; Graus, A. S.; Adams, F. C.; Segura-Cox, D. M.

    2013-02-15

    Some theories of star formation suggest massive stars may only form in clustered environments, which would create a deficit of massive stars in low-density environments. Observationally, Massey finds such a deficit in samples of the field population in the Small and Large Magellanic Clouds, with an initial mass function (IMF) slope of {Gamma}{sub IMF} {approx} 4. These IMF measurements represent some of the largest known deviations from the standard Salpeter IMF slope of {Gamma}{sub IMF} = 1.35. Here, we carry out a comprehensive investigation of the mass function above 20 M {sub Sun} for the entire field population of the Small Magellanic Cloud (SMC), based on data from the Runaways and Isolated O Type Star Spectroscopic Survey of the SMC (RIOTS4). This is a spatially complete census of the entire field OB star population of the SMC obtained with the IMACS multi-object spectrograph and MIKE echelle spectrograph on the Magellan telescopes. Based on Monte Carlo simulations of the evolved present-day mass function, we find the slope of the field IMF above 20 M {sub Sun} is {Gamma}{sub IMF} = 2.3 {+-} 0.4. We extend our IMF measurement to lower masses using BV photometry from the OGLE II survey. We use a statistical approach to generate a probability distribution for the mass of each star from the OGLE photometry, and we again find {Gamma}{sub IMF} = 2.3 {+-} 0.6 for stellar masses from 7 M {sub Sun} to 20 M {sub Sun }. The discovery and removal of ten runaways in our RIOTS4 sample steepens the field IMF slope to {Gamma}{sub IMF} = 2.8 {+-} 0.5. We discuss the possible effects of binarity and star formation history on our results, and conclude that the steep field massive star IMF is most likely a real effect.

  9. Formate dehydrogenase from the methane oxidizer Methylosinus trichosporium OB3b.

    PubMed Central

    Yoch, D C; Chen, Y P; Hardin, M G

    1990-01-01

    Formate dehydrogenase (NAD+ dependent) was isolated from the obligate methanotroph Methylosinus trichosporium OB3b. When the enzyme was isolated anaerobically, two forms of the enzyme were seen on native polyacrylamide gels, DE-52 cellulose and Sephacryl S-300 columns; they were approximately 315,000 and 155,000 daltons. The enzyme showed two subunits on sodium dodecyl sulfate-polyacrylamide gels. The Mr of the alpha-subunit was 53,800 +/- 2,800, and that of the beta-subunit was 102,600 +/- 3,900. The enzyme (Mr 315,000) was composed of these subunits in an apparent alpha 2 beta 2 arrangement. Nonheme iron was present at a concentration ranging from 11 to 18 g-atoms per mol of enzyme (Mr 315,000). Similar levels of acid-labile sulfide were detected. No other metals were found in stoichiometric amounts. When the enzyme was isolated aerobically, there was no cofactor requirement for NAD reduction; however, when isolated anaerobically, activity was 80 to 90% dependent on the addition of flavin mononucleotide (FMN) to the reaction mixture. Furthermore, the addition of formate to an active, anoxic solution of formate dehydrogenase rapidly inactivated it in the absence of an electron acceptor; this activity could be reconstituted approximately 85% by 50 nM FMN. Flavin adenine dinucleotide could not replace FMN in reconstituting enzyme activity. The Kms of formate dehydrogenase for formate, NAD, and FMN were 146, 200, and 0.02 microM, respectively. "Pseudomonas oxalaticus" formate dehydrogenase, which has physical characteristics nearly identical to those of the M. trichosporium enzyme, was also shown to be inactivated under anoxic conditions by formate and reactivated by FMN. The evolutionary significance of this similarity is discussed. Images PMID:2376564

  10. High-Ionization Gas Associated with a Supershell Surrounding the Perseus OB1 Association

    NASA Astrophysics Data System (ADS)

    Knauth, D. C.; Howk, J. C.; Sembach, K. R.; Lauroesch, J. T.; Meyer, D. M.

    2002-05-01

    We present Far-Ultraviolet Spectroscopic Explorer (FUSE) and Space Telescope Imaging Spectrograph (STIS) observations of high-ionization interstellar absorption toward HD 14434, an O5.5 V star in the Per OB1 Association. This star lies in the direction of the H I supershell GS139-03-69 (Heiles 1979, ApJ, 229, 533). In addition, a supershell-like bubble is detected from WHAM maps of the Perseus arm (Madsen, Haffner, & Reynolds astro-ph/0112232). We detect intermediate velocity interstellar Si IV and C IV absorption centered at VLSR = -73 km s-1, while low-ionization Perseus arm gas is detected at approximately -50 km s-1. Neither N V nor O VI is detected at these velocities, although Fe III, a tracer of warm ionized gas, is seen. The column densities in the -73 km s-1 component are log N(C IV}) = 13.93 +/- 0.02, log N(Si IV}) = 13.35 +/- 0.02, log N(N V}) <= 12.65, and log N(O VI}) <= 13.32. The observed C IV/Si IV ratio of 3.8 +/- 0.3 is similar to the Galactic average. Analysis of the C IV and Si IV line widths yields a temperature of T ~ 12,000 K for this component. No C IV or Si IV is produced via collisions at such low temperatures. We explore two models for the origins of the intermediate velocity C IV and Si IV absorption: photoionization or non-equilibrium collisional processes. Either of these could be related to the origins of the high-ionization gas with a supershell. This work is based on data obtained for the Guaranteed Time Team by the NASA-CNES-CSA FUSE mission. Financial support has been provided by NASA contract NAS5-32985.

  11. A Spitzer Study of Dusty Disks in the Scorpius-Centaurus OB Association

    NASA Astrophysics Data System (ADS)

    Chen, Christine; Mamajek, E. E.; Bitner, M. A.; Pecaut, M.; Su, K. Y. L.; Weinberger, A. J.

    2011-09-01

    We obtained Spitzer Space Telescope Multiband Imaging Photometer for Spitzer (MIPS) 24 micron and 70 micron observations of 183 nearby, Hipparcos F- and G-type common proper motion single and binary systems in the nearest OB association, Scorpius-Centaurus. We also obtained Magellan/MIKE R 50,000 visual spectra at 3500 - 10500 Angstrom for 181 candidate ScoCen stars in single and binary systems. Combining our MIPS observations with those of other ScoCen stars in the literature, we estimate 24 micron F+G-type disk fractions of 9/27 (33% ± 11%), 23/68 (34% ± 7%), and 22/71 (31% ± 7%) for Upper Scorpius ( 10 Myr), Upper Centaurus Lupus ( 15 Myr), and Lower Centaurus Crux ( 17 Myr), respectively. We confirm previous IRAS and MIPS excess detections and present new discoveries of 41 proto-planetary and debris disk systems, with fractional infrared luminosities ranging from LIR/L* = 10-5 - 10-2 and grain temperatures ranging from Tgr = 40 - 300 K. We searched for an increase in 24 micron excess at an age of 15-20 Myr, consistent with the onset of debris production predicted by coagulation N-body simulations of outer planetary systems. We found such an increase around 1.5 Msun stars but discovered a decrease in the 24 micron excess around 1.0 Msunstars. We additionally discovered that the 24 micron excess around 1.0 Msun stars is larger than predicted by self-stirred models. Finally, we found a weak anti-correlation between fractional infrared luminosity (LIR/L*) and chromospheric activity (R'HK), that may be the result of differences in stellar luminosity and/or activity.

  12. Investigating the potential magnetic origin of wind variability in OB stars

    NASA Astrophysics Data System (ADS)

    David-Uraz, Alexandre

    2016-05-01

    In this thesis, the origin of large-scale structures in hot star winds, believed to be responsible for the presence of discrete absorption components (DACs) in the absorption troughs of ultraviolet resonance lines, is constrained using both observations and numerical simulations. These structures are understood as arising from bright regions on the stellar surface, although their physical cause remains unknown. First, we use high quality circular spectropolarimetric observations of 13 well-studied OB stars to evaluate the potential role of dipolar magnetic fields in producing DACs. We perform longitudinal field measurements and place limits on the field strength using Bayesian inference, assuming that it is dipolar. No magnetic field was detected within this sample. The derived constraints statistically refute any significant dynamical influence from a magnetic dipole on the wind for all of these stars, ruling out such fields as a cause for DACs. Second, we perform numerical simulations using bright spots constrained by broadband optical photometric observations. We calculate hydrodynamical wind models using three sets of spot sizes and strengths. Co-rotating interaction regions are yielded in each model, and radiative transfer shows that the properties of the variations in the UV resonance lines synthesized from these models are consistent with those found in observed UV spectra, establishing the first consistent link between UV spectroscopic line profile variability and photometric variations and thus supporting the bright spot paradigm (BSP). Finally, we develop and apply a phenomenological model to quantify the measurable effects co-rotating bright spots would have on broadband optical photometry and on the profiles of photospheric lines in optical spectra. This model can be used to evaluate the existence of these spots, and, in the event of their detection, characterize them. Furthermore, a tentative spot evolution model is presented. A preliminary analysis of

  13. A Correlation between Circumstellar Disks and Rotation in the Upper Scorpius OB Association

    NASA Astrophysics Data System (ADS)

    Dahm, S. E.; Slesnick, Catherine L.; White, R. J.

    2012-01-01

    We present projected rotational velocities for 20 early-type (B8-A9) and 74 late-type (F2-M8) members of the ~5 Myr old Upper Scorpius OB Association derived from high-dispersion optical spectra obtained with the High Resolution Echelle Spectrometer on Keck I and the Magellan Inamori Kyocera Echelle on the Magellan Clay telescope. The spectroscopic sample is composed of stars and brown dwarfs with infrared signatures of circumstellar disks, both primordial and debris, and non-excess sources of comparable spectral type. We merge projected rotational velocities, accretion diagnostics, and Spitzer Space Telescope Infrared Array Camera and Multiband Imaging Photometer for Spitzer 24 μm photometry to examine the relationship between rotation and circumstellar disks. The rotational velocities are strongly correlated with spectral type, a proxy for mass, such that the median vsin i for B8-A9-type stars is: 195 ± 70 km s-1, F2-K4: 37.8 ± 7.4 km s-1, K5-K9: 13.8+21.3 - 8.2 km s-1, M0-M5: 16.52 ± 5.3 km s-1, and M5.5-M8: 17.72 ± 8.1 km s-1. We find with a probability of >=0.99 that M-type stars and brown dwarfs having infrared excess suggestive of circumstellar disks rotate more slowly than their non-excess counterparts. A similar correlation is present among F2-K9-type stars, but only at the ~97% confidence level. Among the early-type (B8-A9) members, rotational velocities of the debris-disk and non-disk populations are indistinguishable. Considering the late-type (F2-M8) stars and brown dwarfs, we find a low fraction of slowly rotating, non-excess sources relative to younger star-forming regions, suggesting that most have spun up following disk dissipation. The few late-type (F2-M5) debris disk sources, which may be representative of stars that have recently dispersed their inner disks, are evenly divided between slow and moderate rotators.

  14. NEAR-INFRARED VARIABILITY IN YOUNG STARS IN CYGNUS OB7

    SciTech Connect

    Rice, Thomas S.; Wolk, Scott J.; Aspin, Colin

    2012-08-10

    We present the first results from a 124 night J, H, K near-infrared monitoring campaign of the dark cloud L 1003 in Cygnus OB7, an active star-forming region. Using three seasons of UKIRT observations spanning 1.5 years, we obtained high-quality photometry on 9200 stars down to J = 17 mag, with photometric uncertainty better than 0.04 mag. On the basis of near-infrared excesses from disks, we identify 30 pre-main-sequence stars, including 24 which are newly discovered. We analyze those stars and find that the NIR excesses are significantly variable. All 9200 stars were monitored for photometric variability; among the field star population, {approx}160 exhibited near-infrared variability (1.7% of the sample). Of the 30 young stellar objects (YSOs), 28 of them (93%) are variable at a significant level. Of the 30 YSOs, twenty-five have near-infrared excess consistent with simple disk-plus-star classical T Tauri models. Nine of these (36%) drift in color space over the course of these observations and/or since Two Micron All Sky Survey observations such that they cross the boundary defining the NIR excess criteria; effectively, they have a transient near-infrared excess. Thus, time-series JHK observations can be used to obtain a more complete sample of disk-bearing stars than single-epoch JHK observations. About half of the YSOs have color-space variations parallel to either the classical T Tauri star locus or a hybrid track which includes the dust reddening trajectory. This indicates that the NIR variability in YSOs that possess accretion disks arises from a combination of variable extinction and changes in the inner accretion disk: either in accretion rate, central hole size, and/or the inclination of the inner disk. While some variability may be due to stellar rotation, the level of variability on the individual stars can exceed a magnitude. This is a strong empirical suggestion that protoplanetary disks are quite dynamic and exhibit more complex activity on short

  15. Deep Stucture of the Northwestern Atlantic Moroccan Margin Studied by OBS and Deep Multichannel Seismic Reflection.

    NASA Astrophysics Data System (ADS)

    MALOD, J. A.; Réhault, J.; Sahabi, M.; Géli, L.; Matias, L.; Diaz, J.; Zitellini, N.

    2001-12-01

    The Northwestern Atlantic Moroccan margin, a conjugate of the New Scotland margin, is one of the oldest passive margin of the world. Continental break up occurred at early Liassic time and the deep margin is characterized by a large salt basin. A good knowledge of this basin is of major interest to improve the initial reconstruction between Africa, North America and Iberia (Eurasia). It is also a good opportunity to study a mature passive margin and model its structure and evolution.Moreover, there is a need to assess the geological hazards linked to the neotectonic activity within the Africa-Eurasia plate boundary. These topics have been adressed during the SISMAR cruise carried out from April 9th to May 4th 2001.During this cruise, 3667 km of multichannel seismic reflection (360 channels, 4500 m long streamer, 4800 ci array of air guns) were recorded together with refraction records by means of 48 OBH/OBS drops. Simultaneously, some of the marine profiles have been extended onshore with 16 portable seismic land stations. We present the initial results of this study. Off El Jadida, the Moho and structures within the thinned continental crust are well imaged on both the reflection and refraction records. In the northern area, off Casablanca, we follow the deepening of the moroccan margin beneath the up to 9 sec (twtt) allochtonous series forming a prism at the front the Rif-Betic chain. Sismar cruise has been also the opportunity to record long seismic profiles making the junction between the Portuguese margin and the Moroccan one, and crossing the Iberian-African plate boundary. This allows to observe the continuity of the sedimentary sequence after the end of the large inter-plate motion in Early Cretaceous. In addition to the authors, SISMAR Group includes: AMRHAR Mostafa, BERMUDEZ VASQUEZ Antoni, CAMURRI Francesca, CONTRUCCI Isabelle, CORELA Carlos, DIAZ Jordi, DORVAL Philippe, EL ARCHI Abdelkrim, EL ATTARI Ahmed, GONZALEZ Raquel, HARMEGNIES Francois, JAFFAL

  16. Physical properties of seven binary and higher-order multiple OB systems

    NASA Astrophysics Data System (ADS)

    Mayer, Pavel; Harmanec, Petr; Chini, Rolf; Nasseri, Anita; Nemravová, Jana A.; Drechsel, Horst; Catalan-Hurtado, Rodrigo; Barlow, Brad N.; Frémat, Yves; Kotková, Lenka

    2017-03-01

    Analyses of multi-epoch, high-resolution (R 50 000) optical spectra of seven early-type systems provided various important new insights with respect to their multiplicity. First determinations of orbital periods were made for HD 92206 C (2.^d022), HD 112244 (27.^d665), HD 164438 (10.^d25), HD 123056 A ( 1314 d) and HD 123056 B (<2 d); the orbital period of HD 318015 could be improved (23.^d445975). Concerning multiplicity, a third component was discovered for HD 92206 C by means of He i line profiles. For HD 93146 A, which was hitherto assumed to be SB1, lines of a secondary component could be discerned. HD 123056 turns out to be a multiple system consisting of a high-mass component A (≈O8.5) displaying a broad He ii 5411 Å feature with variable radial velocity, and of an inner pair B (≈B0) with double He i lines. The binary HD 164816 was revisited and some of its system parameters were improved. In particular, we determined its systemic velocity to be -7 km s-1, which coincides with the radial velocity of the cluster NGC 6530. This fact, together with its distance, suggests the cluster membership of HD 164816. The OB system HD 318015 (V1082 Sco) belongs to the rare class of eclipsing binaries with a supergiant primary (B0.5/0.7). Our combined orbital and light-curve analysis suggests that the secondary resembles an O9.5 III star. Our results for a limited sample corroborate the findings that many O stars are actually massive multiple systems. Based on spectra from observations made with ESO telescopes at La Silla and Paranal Observatories under programs 065.1-0526(A), 073.C-0337(A), 074.D-0300(A), 075.D-0103(A), 077.D-0705(A), 077.B-0348(A), 079.D-0564(A), 081.D-2008(A), 083.D-0589(A), 085.D-0262(A), 086.D-0997(A), 087.C-0012(A), 087.D-0946(A), 089.C-0415(A), 089.D-0097(B), 089.D-0975(A), 090.C-0280(A), 091.D-0145(A), 095.A-9032(A), and 178.D-0361(E), program TYCHO P2, on the BESO spectra and spectra from CTIO, and on the Hipparcos Hp and ASAS3 V photometry.

  17. Breakup Style and Magmatic Underplating West of the Lofoten Islands, Norway, Based on OBS Data.

    NASA Astrophysics Data System (ADS)

    Breivik, A. J.; Faleide, J. I.; Mjelde, R.; Murai, Y.; Flueh, E. R.

    2014-12-01

    The breakup of the Northeast Atlantic in the Early Eocene was magma-rich, forming the major part of the North Atlantic Igneous Province (NAIP). This is seen as extrusive and intrusive magmatism in the continental domain, and as a thicker than normal oceanic crust produced the first few million years after continental breakup. The maximum magma productivity and the duration of excess magmatism varies along the margins of Northwest Europe and East Greenland, to some extent as a function of the distance from the Iceland hotspot. The Vøring Plateau off mid-Norway is the northernmost of the margin segments in northwestern Europe with extensive magmatism. North of the plateau, magmatism dies off towards the Lofoten Margin, marking the northern boundary of the NAIP here. In 2003, as part of the Euromargins Program we collected an Ocean Bottom Seismometer (OBS) profile from mainland Norway, across the Lofoten Islands, and out into the deep ocean. Forward velocity modeling using raytracing reveals a continental margin that shows transitional features between magma-rich and magma-poor rifting. On one hand, we detect an up to 2 km thick and 40-50 km wide magmatic underplate of the outer continent, on the other hand, continental thinning is greater and intrusive magmatism less than farther south. Continental breakup also appears to be somewhat delayed compared to breakup on the Vøring Plateau, consistent with increased extension. This indicates that magmatic diking, believed to quickly lead to continental breakup of volcanic margins and thus to reduce continental thinning, played a much lesser role here than at the plateau. Early post-breakup oceanic crust is up to 8 km thick, less than half of that observed farther south. The most likely interpretation of these observations, is that the source for the excess magmatism of the NAIP was not present at the Lofoten Margin during rifting, and that the excess magmatism actually observed was the result of lateral transport from the

  18. The Star-formation History and Accretion Disk Fraction of the Scorpius-Centaurus OB Association

    NASA Astrophysics Data System (ADS)

    Pecaut, Mark; Mamajek, E. E.

    2013-01-01

    We present a study of the star-formation history and accretion disk fraction of ~0.6-1.8 Msun stars in the nearest OB Association, Scorpius-Centaurus (Sco-Cen; ~10-20 Myr; 100-200 pc). We have performed a low-resolution spectroscopic survey for new, low-mass K- and M-type members of all three subgroups -- Upper Scorpius (US), Upper Centaurus-Lupus (UCL) and Lower Centaurus-Crux (LCC). We find that young, pre-main sequence stars are generally redder and hotter for a given spectral type than their main-sequence counterparts and therefore main-sequence intrinsic colors and temperatures are unsuitable for de-reddening the low-mass members of Sco-Cen and placing them on an H-R diagram. Using nearby, young moving groups within 75 pc, we derive a spectral type--intrinsic color sequence appropriate for pre-main sequence stars, and use synthetic spectral energy distribution fits to infer the proper temperature scale for these young stars. We use this new pre-main sequence intrinsic color and temperature calibration to place our ~200 newly identified members of Sco-Cen on an H-R diagram. We derive isochronal ages for the F-type members of Upper Centaurus-Lupus (UCL; 16 Myr; =142 pc) and Lower Centaurus-Crux (LCC; 17 Myr; =118 pc) which are consistent with the most recent results from the high-mass stars and the G- and K-type stars. However, our results for Upper Scorpius (US; 11 Myr; =145 pc) indicate it is a factor of two older than previously thought. Finally, we find an accretion disk fraction for UCL and LCC of ~3% for K-type stars decreasing to 2% for F-type stars at ~16-17 Myr, while US has an accretion disk fraction of 5% for K-type stars decreasing to <19% (95% C.L.) for F-type stars at ~11 Myr.

  19. The Anisotropic Structure of South China Sea: Using OBS Data to Constrain Mantle Flow

    NASA Astrophysics Data System (ADS)

    Li, L.; Xue, M.; Yang, T.; Liu, C.; Hua, Q.; Xia, S.; Huang, H.; Le, B. M.; Huo, D.; Pan, M.

    2015-12-01

    The dynamic mechanism of the formation of South China Sea (SCS) has been debated for decades. The anisotropic structure can provide useful insight into the complex evolution of SCS by indicating its mantle flow direction and strength. In this study, we employ shear wave splitting methods on two half-year seismic data collected from 10 and 6 passive source Ocean Bottom Seismometers (OBS) respectively. These OBSs were deployed along both sides of the extinct ridge in the central basin of SCS by Tongji University in 2012 and 2013 respectively, which were then successfully recovered in 2013 and 2015 respectively. Through processing and inspecting the global and regional earthquakes (with local events being processing) of the 2012 dataset, measurements are made for 2 global events and 24 regional events at 5 OBSs using the tangential energy minimization, the smallest eigenvalue minimization, as well as the correlation methods. We also implement cluster analysis on the splitting results obtained for different time windows as well as filtered at different frequency bands. For teleseismic core phases like SKS and PKS, we find the fast polarization direction beneath the central basin is approximately NE-SW, nearly parallel to the extinct ridge in the central basin of SCS. Whereas for regional events, the splitting analysis on S, PS and ScS phases shows much more complicated fast directions as the ray path varies for different phases. The fast directions observed can be divided into three groups: (1) for the events from the Eurasia plate, a gradual rotation of the fast polarization direction from NNE-SSW to NEE-SWW along the path from the inner Eurasia plate to the central SCS is observed, implying the mantle flow is controlled by the India-Eurasia collision; (2) for the events located at the junction of Pacific plate and Philippine plate, the dominant fast direction is NW-SE, almost perpendicular to Ryukyu Trench as well as sub-parallel to the absolute direction of

  20. HD 144548: A young triply eclipsing system in the Upper Scorpius OB association

    NASA Astrophysics Data System (ADS)

    Alonso, R.; Deeg, H. J.; Hoyer, S.; Lodieu, N.; Palle, E.; Sanchis-Ojeda, R.

    2015-12-01

    The star HD 144548 (=HIP 78977; TYP 6212-1273-1) has been known as a detached eclipsing binary and a bona-fide member of the Upper Scorpius OB association. Continuous photometry from the K2 mission on Campaign Two has revealed the presence of additional eclipses due to the presence of a third star in the system. These are explained by a system composed of the two previously known members of the eclipsing system (Ba and Bb) with a period of 1.63 d, orbiting around an F7-F8V star with a period of 33.945 ± 0.002 d in an eccentric orbit (eA = 0.2652 ± 0.0003). The timing of the eclipses of Ba and Bb reveals the same 33.9 d periodicity, which we interpret as the combination of a light time effect combined with dynamical perturbations on the close system. Here we combine radial velocities and analytical approximations for the timing of the eclipses to derive masses and radii for the three components of the system. We obtain a mass of 1.44 ± 0.04 M⊙ and radius of 2.41 ± 0.03 R⊙ for the A component, and almost identical masses and radii of about 0.96 M⊙ and 1.33 R⊙ for each of the two components of the close binary. HD 144548 is the first triply eclipsing system for which radial velocities of all components could be measured. Partially based on observations made with the Italian Telescopio Nazionale Galileo (TNG) operated by the Fundación Galileo Galilei of the INAF, the Nordic Optical Telescope, operated by the Nordic Optical Telescope Scientific Association, and the William Herschel Telescope (programme DDT58 - PI Lodieu) operated by the Isaac Newton Group on the island of La Palma at the Spanish Observatorio Roque de los Muchachos of the IAC. This paper includes data collected by the Kepler mission. Funding for the Kepler mission is provided by the NASA Science Mission directorate.Appendices are available in electronic form at http://www.aanda.org

  1. An Updated Look at Binary Characteristics of Massive Stars in the Cygnus OB2 Association

    NASA Astrophysics Data System (ADS)

    Kiminki, Daniel C.; Kobulnicky, Henry A.

    2012-05-01

    This work provides a statistical analysis of the massive star binary characteristics in the Cygnus OB2 association using radial velocity information of 114 B3-O5 primary stars and orbital properties for the 24 known binaries. We compare these data to a series of Monte Carlo simulations to infer the intrinsic binary fraction and distributions of mass ratios, periods, and eccentricities. We model the distribution of mass ratio, log-period, and eccentricity as power laws and find best-fitting indices of α = 0.1 ± 0.5, β = 0.2 ± 0.4, and γ = -0.6 ± 0.3, respectively. These distributions indicate a preference for massive companions, short periods, and low eccentricities. Our analysis indicates that the binary fraction of the cluster is 44% ± 8% if all binary systems are (artificially) assumed to have P < 1000 days; if the power-law period distribution is extrapolated to 104 years, then a plausible upper limit for bound systems, the binary fraction is ~90% ± 10%. Of these binary (or higher order) systems, ~45% will have companions close enough to interact during pre- or post-main-sequence evolution (semi-major axis lsim4.7 AU). The period distribution for P < 26 days is not well reproduced by any single power law owing to an excess of systems with periods around 3-5 days (0.08-0.31 AU) and a relative shortage of systems with periods around 7-14 days (0.14-0.62 AU). We explore the idea that these longer-period systems evolved to produce the observed excess of short-period systems. The best-fitting binary parameters imply that secondaries generate, on average, ~16% of the V-band light in young massive populations. This means that photometrically based distance measurements for young massive clusters and associations will be systematically low by ~8% (0.16 mag in the distance modulus) if the luminous contributions of unresolved secondaries are not taken into account.

  2. A TonB-Dependent Transporter Is Responsible for Methanobactin Uptake by Methylosinus trichosporium OB3b

    PubMed Central

    Gu, Wenyu; Farhan Ul Haque, Muhammad; Baral, Bipin S.; Turpin, Erick A.; Bandow, Nathan L.; Kremmer, Elisabeth; Flatley, Andrew; Zischka, Hans; DiSpirito, Alan A.

    2016-01-01

    Methanobactin, a small modified polypeptide synthesized by methanotrophs for copper uptake, has been found to be chromosomally encoded. The gene encoding the polypeptide precursor of methanobactin, mbnA, is part of a gene cluster that also includes several genes encoding proteins of unknown function (but speculated to be involved in methanobactin formation) as well as mbnT, which encodes a TonB-dependent transporter hypothesized to be responsible for methanobactin uptake. To determine if mbnT is truly responsible for methanobactin uptake, a knockout was constructed in Methylosinus trichosporium OB3b using marker exchange mutagenesis. The resulting M. trichosporium mbnT::Gmr mutant was found to be able to produce methanobactin but was unable to internalize it. Further, if this mutant was grown in the presence of copper and exogenous methanobactin, copper uptake was significantly reduced. Expression of mmoX and pmoA, encoding polypeptides of the soluble methane monooxygenase (sMMO) and particulate methane monooxygenase (pMMO), respectively, also changed significantly when methanobactin was added, which indicates that the mutant was unable to collect copper under these conditions. Copper uptake and gene expression, however, were not affected in wild-type M. trichosporium OB3b, indicating that the TonB-dependent transporter encoded by mbnT is responsible for methanobactin uptake and that methanobactin is a key mechanism used by methanotrophs for copper uptake. When the mbnT::Gmr mutant was grown under a range of copper concentrations in the absence of methanobactin, however, the phenotype of the mutant was indistinguishable from that of wild-type M. trichosporium OB3b, indicating that this methanotroph has multiple mechanisms for copper uptake. PMID:26773085

  3. Search for OB stars running away from young star clusters. II. The NGC 6357 star-forming region

    NASA Astrophysics Data System (ADS)

    Gvaramadze, V. V.; Kniazev, A. Y.; Kroupa, P.; Oh, S.

    2011-11-01

    Dynamical few-body encounters in the dense cores of young massive star clusters are responsible for the loss of a significant fraction of their massive stellar content. Some of the escaping (runaway) stars move through the ambient medium supersonically and can be revealed via detection of their bow shocks (visible in the infrared, optical or radio). In this paper, which is the second of a series of papers devoted to the search for OB stars running away from young ( ≲ several Myr) Galactic clusters and OB associations, we present the results of the search for bow shocks around the star-forming region NGC 6357. Using the archival data of the Midcourse Space Experiment (MSX) satellite and the Spitzer Space Telescope, and the preliminary data release of the Wide-Field Infrared Survey Explorer (WISE), we discovered seven bow shocks, whose geometry is consistent with the possibility that they are generated by stars expelled from the young (~1-2 Myr) star clusters, Pismis 24 and AH03 J1725-34.4, associated with NGC 6357. Two of the seven bow shocks are driven by the already known OB stars, HD 319881 and [N78] 34. Follow-up spectroscopy of three other bow-shock-producing stars showed that they are massive (O-type) stars as well, while the 2MASS photometry of the remaining two stars suggests that they could be B0 V stars, provided that both are located at the same distance as NGC 6357. Detection of numerous massive stars ejected from the very young clusters is consistent with the theoretical expectation that star clusters can effectively lose massive stars at the very beginning of their dynamical evolution (long before the second mechanism for production of runaway stars, based on a supernova explosion in a massive tight binary system, begins to operate) and lends strong support to the idea that probably all field OB stars have been dynamically ejected from their birth clusters. A by-product of our search for bow shocks around NGC 6357 is the detection of three circular

  4. Globules and pillars in Cygnus X. I. Herschel far-infrared imaging of the Cygnus OB2 environment

    NASA Astrophysics Data System (ADS)

    Schneider, N.; Bontemps, S.; Motte, F.; Blazere, A.; André, Ph.; Anderson, L. D.; Arzoumanian, D.; Comerón, F.; Didelon, P.; Di Francesco, J.; Duarte-Cabral, A.; Guarcello, M. G.; Hennemann, M.; Hill, T.; Könyves, V.; Marston, A.; Minier, V.; Rygl, K. L. J.; Röllig, M.; Roy, A.; Spinoglio, L.; Tremblin, P.; White, G. J.; Wright, N. J.

    2016-06-01

    The radiative feedback of massive stars on molecular clouds creates pillars, globules and other features at the interface between the H II region and molecular cloud. Optical and near-infrared observations from the ground as well as with the Hubble or Spitzer satellites have revealed numerous examples of such cloud structures. We present here Herschel far-infrared observations between 70 μm and 500 μm of the immediate environment of the rich Cygnus OB2 association, performed within the Herschel imaging survey of OB Young Stellar objects (HOBYS) program. All of the observed irradiated structures were detected based on their appearance at 70 μm, and have been classified as pillars, globules, evaporating gasous globules (EGGs), proplyd-like objects, and condensations. From the 70 μm and 160 μm flux maps, we derive the local far-ultraviolet (FUV) field on the photon dominated surfaces. In parallel, we use a census of the O-stars to estimate the overall FUV-field, that is 103-104 G0 (Habing field) close to the central OB cluster (within 10 pc) and decreases down to a few tens G0, in a distance of 50 pc. From a spectral energy distribution (SED) fit to the four longest Herschel wavelengths, we determine column density and temperature maps and derive masses, volume densities and surface densities for these structures. We find that the morphological classification corresponds to distinct physical properties. Pillars and globules are massive (~500 M⊙) and large (equivalent radius r ~ 0.6 pc) structures, corresponding to what is defined as "clumps" for molecular clouds. EGGs and proplyd-likeobjects are smaller (r ~ 0.1 and 0.2 pc) and less massive (~10 and ~30 M⊙). Cloud condensations are small (~0.1 pc), have an average mass of 35 M⊙, are dense (~6 × 104 cm-3), and can thus be described as molecular cloud "cores". All pillars and globules are oriented toward the Cyg OB2 association center and have the longest estimated photoevaporation lifetimes, a few million

  5. Analysis of MSS (Marine Seismic System) and OBS (Ocean Bottom Seismograph) Data Collected during the NGENDEI Seismic Experiment

    DTIC Science & Technology

    1986-08-01

    REPORT DOCUMENTATION PAGE 11 T ClSiIAj b. RESTRICTIVE MARKINGS 2a, 3TC-uniT CLASSIFICATION AUTHORITY 3. DISTRIBUTION/AVAI LABILITY OF REPORT ...ApptvIoVd topbIf T6 2.. DCLASSI FICATION/DOWNO RADING SCHEDULE ditibto U11111 .PEFRIGOGNZTOREOTNUMBER(S) 5. MO19IGOGNZTION REPORT NUMSER...1PROJECT TASK WORK UNIT ELEMENTN. NO. NO. NO. 11. TITLft (Includ ac riyLu.Icaf Analysis of MSS and OBS Data Collected During the NGENDEI Sp ismic Expqriment

  6. Cloud Structure of Galactic OB Cluster-forming Regions from Combining Ground- and Space-based Bolometric Observations

    NASA Astrophysics Data System (ADS)

    Lin, Yuxin; Liu, Hauyu Baobab; Li, Di; Zhang, Zhi-Yu; Ginsburg, Adam; Pineda, Jaime E.; Qian, Lei; Galván-Madrid, Roberto; McLeod, Anna Faye; Rosolowsky, Erik; Dale, James E.; Immer, Katharina; Koch, Eric; Longmore, Steve; Walker, Daniel; Testi, Leonardo

    2016-09-01

    We have developed an iterative procedure to systematically combine the millimeter and submillimeter images of OB cluster-forming molecular clouds, which were taken by ground-based (CSO, JCMT, APEX, and IRAM-30 m) and space telescopes (Herschel and Planck). For the seven luminous (L\\gt {10}6 L ⊙) Galactic OB cluster-forming molecular clouds selected for our analyses, namely W49A, W43-Main, W43-South, W33, G10.6-0.4, G10.2-0.3, and G10.3-0.1, we have performed single-component, modified blackbody fits to each pixel of the combined (sub)millimeter images, and the Herschel PACS and SPIRE images at shorter wavelengths. The ˜10″ resolution dust column density and temperature maps of these sources revealed dramatically different morphologies, indicating very different modes of OB cluster-formation, or parent molecular cloud structures in different evolutionary stages. The molecular clouds W49A, W33, and G10.6-0.4 show centrally concentrated massive molecular clumps that are connected with approximately radially orientated molecular gas filaments. The W43-Main and W43-South molecular cloud complexes, which are located at the intersection of the Galactic near 3 kpc (or Scutum) arm and the Galactic bar, show a widely scattered distribution of dense molecular clumps/cores over the observed ˜10 pc spatial scale. The relatively evolved sources G10.2-0.3 and G10.3-0.1 appear to be affected by stellar feedback, and show a complicated cloud morphology embedded with abundant dense molecular clumps/cores. We find that with the high angular resolution we achieved, our visual classification of cloud morphology can be linked to the systematically derived statistical quantities (i.e., the enclosed mass profile, the column density probability distribution function (N-PDF), the two-point correlation function of column density, and the probability distribution function of clump/core separations). In particular, the massive molecular gas clumps located at the center of G10.6-0.4 and

  7. The CIDA-QUEST large-scale survey of Orion OB1: evidence for rapid disk dissipation in a dispersed stellar population.

    PubMed

    Briceño, C; Vivas, A K; Calvet, N; Hartmann, L; Pacheco, R; Herrera, D; Romero, L; Berlind, P; Sánchez, G; Snyder, J A; Andrews, P

    2001-01-05

    We are conducting a large-scale, multiepoch, optical photometric survey [Centro de Investigaciones de Astronomia-Quasar Equatorial Survey Team (CIDA-QUEST)] covering about 120 square degrees to identify the young low-mass stars in the Orion OB1 association. We present results for an area of 34 square degrees. Using photometric variability as our main selection criterion, as well as follow-up spectroscopy, we confirmed 168 previously unidentified pre-main sequence stars that are about 0.6 to 0.9 times the mass of the sun (Mo), with ages of about 1 million to 3 million years (Ori OB1b) and about 3 million to 10 million years (Ori OB1a). The low-mass stars are spatially coincident with the high-mass (at least 3 Mo) members of the associations. Indicators of disk accretion such as Halpha emission and near-infrared emission from dusty disks fall sharply from Ori OB1b to Ori OB1a, indicating that the time scale for disk dissipation and possibly the onset of planet formation is a few million years.

  8. ATP-dependent DNA ligase from Thermococcus sp. 1519 displays a new arrangement of the OB-fold domain.

    PubMed

    Petrova, T; Bezsudnova, E Y; Boyko, K M; Mardanov, A V; Polyakov, K M; Volkov, V V; Kozin, M; Ravin, N V; Shabalin, I G; Skryabin, K G; Stekhanova, T N; Kovalchuk, M V; Popov, V O

    2012-12-01

    DNA ligases join single-strand breaks in double-stranded DNA by catalyzing the formation of a phosphodiester bond between adjacent 5'-phosphate and 3'-hydroxyl termini. Their function is essential for maintaining genome integrity in the replication, recombination and repair of DNA. High flexibility is important for the function of DNA ligase molecules. Two types of overall conformations of archaeal DNA ligase that depend on the relative position of the OB-fold domain have previously been revealed: closed and open extended conformations. The structure of ATP-dependent DNA ligase from Thermococcus sp. 1519 (LigTh1519) in the crystalline state determined at a resolution of 3.02 Å shows a new relative arrangement of the OB-fold domain which is intermediate between the positions of this domain in the closed and the open extended conformations of previously determined archaeal DNA ligases. However, small-angle X-ray scattering (SAXS) measurements indicate that in solution the LigTh1519 molecule adopts either an open extended conformation or both an intermediate and an open extended conformation with the open extended conformation being dominant.

  9. Paraffin oil as a "methane vector" for rapid and high cell density cultivation of Methylosinus trichosporium OB3b.

    PubMed

    Han, Bing; Su, Tao; Wu, Hao; Gou, Zhongxuan; Xing, Xin-Hui; Jiang, Hao; Chen, Yin; Li, Xin; Murrell, J Colin

    2009-06-01

    Slow growth and relatively low cell densities of methanotrophs have limited their uses in industrial applications. In this study, a novel method for rapid cultivation of Methylosinus trichosporium OB3b was studied by adding a water-immiscible organic solvent in the medium. Paraffin oil was the most effective at enhancing cell growth and final cell density. This is at least partially due to the increase of methane gas transfer between gas and medium phases since methane solubility is higher in paraffin than in water/nitrate minimal salt medium. During cultivation with paraffin oil at 5% (v/v) in the medium, M. trichosporium OB3b cells also showed higher concentrations of the intermediary metabolites, such as formic acid and pyruvic acid, and consumed more methane compared with the control. Paraffin as methane vector to improve methanotroph growth was further studied in a 5-L fermentor at three concentrations (i.e., 2.5%, 5%, and 10%). Cell density reached about 14 g dry weight per liter with 5% paraffin, around seven times higher than that of the control (without paraffin). Cells cultivated with paraffin tended to accumulate around the interface between oil droplets and the water phase and could exist in oil phase in the case of 10% (v/v) paraffin. These results indicated that paraffin could enhance methanotroph growth, which is potentially useful in cultivation of methanotrophs in large scale in industry.

  10. Multifunctional Bi{sub 2}ZnOB{sub 2}O{sub 6} single crystals for second and third order nonlinear optical applications

    SciTech Connect

    Iliopoulos, K.; Kasprowicz, D.; Majchrowski, A.; Michalski, E.; Gindre, D.; Sahraoui, B.

    2013-12-02

    Bi{sub 2}ZnOB{sub 2}O{sub 6} nonlinear optical single crystals were grown by means of the Kyropoulos method from stoichiometric melt. The second and third harmonic generation (SHG/THG) of Bi{sub 2}ZnOB{sub 2}O{sub 6} crystals were investigated by the SHG/THG Maker fringes technique. Moreover, SHG microscopy studies were carried out providing two-dimensional SHG images as a function of the incident laser polarization. The high nonlinear optical efficiency combined with the possibility to grow high quality crystals make Bi{sub 2}ZnOB{sub 2}O{sub 6} an excellent candidate for photonic applications.

  11. Noise on broadband Ocean Bottom Seismometers (OBS) from the German (DEPAS) and French (INSU) instruments pools as recorded in the RHUM-RUM project

    NASA Astrophysics Data System (ADS)

    Stähler, Simon C.; Sigloch, Karin; Barruol, Guilhem; Hosseini, Kasra; Crawford, Wayne C.; Schmidt-Aursch, Mechita; Tsekhmistrenko, Maria; Scholz, John-Robert; Deen, Martha; Mazzullo, Alessandro

    2016-04-01

    A long-standing discussion in the OBS community is about the influence of OBS design on noise levels of seismic records. We present results from the RHUM-RUM experiment in the Indian Ocean. RHUM-RUM is a German-French seismological experiment based on the sea floor surrounding the island of La Réunion, western Indian Ocean. RHUM-RUM's central component is a 13-month deployment (Oct 2012 to Nov 2013) of 57 broad- and wideband ocean bottom seismometers (OBS) and hydrophones over an area of 2000x2000 km2 surrounding the hotspot. The array contained 48 wideband OBS from the German DEPAS pool and 9 broadband OBS from the French INSU pool. It is the largest deployment of DEPAS and INSU OBS so far, and the first joint experiment. Therefore it allows to compare the performance of these distinct instrument types in different ocean-floor environments. The INSU seismic sensors stand away from their OBS frames, whereas the DEPAS sensors are integrated into theirs. At long periods (>10 s), the DEPAS seismometers are affected by significantly stronger noise than the INSU seismometers. On the horizontal components, this can be explained by tilting of the frame and buoy assemblage, e.g., through the action of ocean-bottom currents. However, the long period noise level on the vertical components suggests that the DEPAS intruments are also affected by significant self-noise of the CMG-40TOBS seismometer itself. By comparison, the INSU instruments (Trillium 240OBS sensors) are much quieter at periods >30 s and hence better suited for long-period studies. The trade-off of the instrument design is that the integrated DEPAS setup is easier to deploy and recover, especially when large numbers of stations are involved or fast deployment/recovery of the instruments is desired (e.g. active experiments). Additionally, the wideband sensor has only half the power consumption of the broadband INSU seismometers. This presentation also reviews network performance and data quality: Of the 57

  12. A study of the evolutionary stages of IRAS sources and outflows in the Mon OB1 dark cloud

    NASA Technical Reports Server (NTRS)

    Wolf-Chase, G.; Davidson, J.

    1997-01-01

    An ongoing project aiming to relate the evolutionary stages of the Infrared Astronomy Satellite (IRAS) sources in the Mon OB1 dark cloud to the morphology and energetics of outflows associated with some of these sources, is reported on. Previous evolutionary classifications of IRAS sources are refined and potential class O objects are identified. The fully-sampled CO maps of the outflows in this cloud are presented. These observations yield information on outflow structure, kinematics and excitation conditions. Low-intensity, high velocity gas is observed in the youngest outflows. This emission is characterized by relatively flat line wings at the highest velocities in spectral line profiles obtained at the peaks of the outflow emission.

  13. Measuring Doppler Shifts of X-Ray Lines to Determine the Stellar Wind X-Ray Locations in OB Stars

    NASA Astrophysics Data System (ADS)

    Waldron, Wayne

    1999-09-01

    For almost 20 years we have been trying to determine the source of the X-ray emission in OB stars. It is generally believed that this emission is caused by a distribution of stellar wind shocks. The AXAF grating spectrometers will provide the ultimate test of X-ray models. The shock model predicts that X-ray lines must be Doppler blue-shifted, hence, our primary objective is to measure these blue-shifts. MARX simulations show that the expected X-ray line shifts will be at least 4 times the MEG1 energy resolution limit. ASCA observations have provided stronger constraints on X-ray models, but they have also raised additional questions (e.g., X-ray abundance anomalies). The large number of X-ray lines predicted by MARX simulations will allow us to probe X-ray densities and abundances.

  14. TOWARD COMPLETE STATISTICS OF MASSIVE BINARY STARS: PENULTIMATE RESULTS FROM THE CYGNUS OB2 RADIAL VELOCITY SURVEY

    SciTech Connect

    Kobulnicky, Henry A.; Lundquist, Michael J.; Burke, Jamison; Chapman, James; Keller, Erica; Lester, Kathryn; Rolen, Emily K.; Topel, Eric; Bhattacharjee, Anirban; Smullen, Rachel A.; Álvarez, Carlos A. Vargas; Runnoe, Jessie C.; Dale, Daniel A.; Brotherton, Michael M.; Kiminki, Daniel C. E-mail: jburke2@swarthmore.edu E-mail: kelle22e@mtholyoke.edu E-mail: emily.k.rolen@vanderbilt.edu

    2014-08-01

    We analyze orbital solutions for 48 massive multiple-star systems in the Cygnus OB2 association, 23 of which are newly presented here, to find that the observed distribution of orbital periods is approximately uniform in log P for P < 45 days, but it is not scale-free. Inflections in the cumulative distribution near 6 days, 14 days, and 45 days suggest key physical scales of ≅0.2, ≅0.4, and ≅1 A.U. where yet-to-be-identified phenomena create distinct features. No single power law provides a statistically compelling prescription, but if features are ignored, a power law with exponent β ≅ –0.22 provides a crude approximation over P = 1.4-2000 days, as does a piece-wise linear function with a break near 45 days. The cumulative period distribution flattens at P > 45 days, even after correction for completeness, indicating either a lower binary fraction or a shift toward low-mass companions. A high degree of similarity (91% likelihood) between the Cyg OB2 period distribution and that of other surveys suggests that the binary properties at P ≲ 25 days are determined by local physics of disk/clump fragmentation and are relatively insensitive to environmental and evolutionary factors. Fully 30% of the unbiased parent sample is a binary with period P < 45 days. Completeness corrections imply a binary fraction near 55% for P < 5000 days. The observed distribution of mass ratios 0.2 < q < 1 is consistent with uniform, while the observed distribution of eccentricities 0.1 < e < 0.6 is consistent with uniform plus an excess of e ≅ 0 systems. We identify six stars, all supergiants, that exhibit aperiodic velocity variations of ∼30 km s{sup –1} attributed to atmospheric fluctuations.

  15. Migration of global radioactive fallout to the Arctic Ocean (on the example of the Ob's river drainage basin).

    PubMed

    Miroshnikov, A; Semenkov, I

    2012-11-01

    This article provides an assessment of the impact of global fallout on (137)Cs contamination in the bottom sediments of Kara Sea. The erosiveness of 10th-level river basins was estimated by landscape-geochemical and geomorphological characteristics. All 10th-level basins (n=154) were separated into three groups: mountain, mountain-lowland and plain. Four different types of basins were identified depending on the geochemical conditions of the migration of radiocaesium in the plain and mountain-lowland. Classifications of types were carried out using the geographic information systems-based approach. The Ob River's macroarena covers 3.5 million km(2). Internal drainage basins cover 23 % of the macroarena and accumulate whole radiocaesium from the global fallout. The remaining territory is transitional for the (137)Cs. The field research works performed in the three plain first-level basins allow one to estimate the radiocaesium run-off. The calculations show that 7 % of (137)Cs was removed from the first-level basin in arable land. Accumulation of radiocaesium in the first-level basin under undisturbed forest is 99.8 %. The research shows that (137)Cs transfer from the humid basins is in the range of 6.9-25.5 TBq and for semi-humid basins 5.6-285.5 TBq. The areas of these basins cover 40 and 8 % of the Ob River's macroarena, respectively. Drainage lakes and reservoir drainage basins make up 22 % of the macroarena. Mountainous and semi-arid drainage basins cover 7 % of the macroarena.

  16. Human breast milk and adipokines--A potential role for the soluble leptin receptor (sOb-R) in the regulation of infant energy intake and development.

    PubMed

    Zepf, F D; Rao, P; Moore, J; Stewart, R; Ladino, Yuli Martinez; Hartmann, B T

    2016-01-01

    Concentrations of different adipokines in human breast milk are thought to be able to affect energy intake of the infant. Leptin is a hormone synthesized by adipose tissue and the human placenta and favors satiety. The availability of leptin in breast milk is influenced by epithelial cells of the mammary gland that are known to be able to produce leptin, as well as leptin from maternal circulation that is transported to the breast milk, and which can thus in turn reach neonatal blood after absorption. Research so far as mainly focused on leptin concentrations in breast milk. However, evidence suggests that in addition to leptin concentrations levels of the so-called soluble leptin receptor (sOb-R), the main high-affinity binding protein for leptin in humans, are necessary in order to calculate the free leptin index (FLI) and to assess function of the leptin axis. FLI is calculated from the ratio of leptin to the sOb-R, and serves as the main parameter for assessing function of the leptin axis throughout maturation and development. Here we propose that assessing sOb-R levels in addition to leptin concentrations in breast milk could serve as a valuable tool to investigate effects of the leptin axis in breast milk because sOb-R concentrations can impact available leptin levels, and which in turn can have significant implications for infant energy intake and related development.

  17. A high angular resolution survey of massive stars in Cygnus OB2: Results from the Hubble space telescope fine guidance sensors

    SciTech Connect

    Caballero-Nieves, S. M.; Gies, D. R.; Jao, W.-C. E-mail: gies@chara.gsu.edu; and others

    2014-02-01

    We present results of a high angular resolution survey of massive OB stars in the Cygnus OB2 association that we conducted with the fine guidance sensor 1R (FGS1r) on the Hubble Space Telescope. FGS1r is able to resolve binary systems with a magnitude difference ΔV < 4 down to separations as small as 0.''01. The sample includes 58 of the brighter members of Cyg OB2, one of the closest examples of an environment containing a large number of very young and massive stars. We resolved binary companions for 12 targets and confirmed the triple nature of one other target, and we offer evidence of marginally resolved companions for two additional stars. We confirm the binary nature of 11 of these systems from complementary adaptive optics imaging observations. The overall binary frequency in our study is 22% to 26% corresponding to orbital periods ranging from 20 to 20,000 yr. When combined with the known short-period spectroscopic binaries, the results support the hypothesis that the binary fraction among massive stars is >60%. One of the new discoveries is a companion to the hypergiant star MT 304 = Cyg OB2-12, and future measurements of orbital motion should provide mass estimates for this very luminous star.

  18. Influence of the Verb Prefix "o-/ob-" on the Distribution of Cases on the Nominal Objects: The Occurrence of Transitive Usage of Unprefixed Verbs.

    ERIC Educational Resources Information Center

    Launer, Michael K.

    1986-01-01

    Investigates the influence of the prefix "o-/ob-" on the choice of case for nominal objects of prefixed verbs, using a semantic field analysis. Focuses on four semantic functions: (1) objective; (2) locative; (3) factitive; and (4) comparative. The results are useful both to theoretical linguists and to teachers of Russian. (LMO)

  19. Non-linear waveform analysis for water-layer response and its application to high-frequency receiver function analysis using OBS array

    NASA Astrophysics Data System (ADS)

    Akuhara, Takeshi; Mochizuki, Kimihiro; Kawakatsu, Hitoshi; Takeuchi, Nozomu

    2016-09-01

    Determination of a response of the sea water column to teleseismic plane wave is important to suppress adverse effects of water reverberations in calculating receiver functions (RFs) using ocean-bottom seismometer (OBS) records. We present a novel non-linear waveform analysis method using the simulated annealing algorithm to determine such a water-layer response recorded by an OBS array. We then demonstrate its usefulness for the RF estimation through its application to synthetic and observed data. Synthetic experiments suggest that the water-layer response constrained in this way has a potential to improve RFs of OBS records drastically even in the high-frequency range (to 4 Hz). By applying it to data observed by the OBS array around the Kii Peninsula, southwestern Japan, we identified a low-velocity zone at the top of the subducting Philippine Sea plate. This zone may represent the incoming fluid-rich sediment layer that has been reported by active-source seismic survey.

  20. Transcriptome profiling of visceral adipose tissue in a novel obese rat model, WNIN/Ob & its comparison with other animal models

    PubMed Central

    Sakamuri, Siva Sankara Vara Prasad; Putcha, Uday Kumar; Veettil, Giridharan Nappan; Ayyalasomayajula, Vajreswari

    2016-01-01

    Background & objectives: Adipose tissue dysfunction in obesity is linked to the development of type 2 diabetes and cardiovascular diseases. We studied the differential gene expression in retroperitoneal adipose tissue of a novel obese rat model, WNIN/Ob, to understand the possible underlying transcriptional changes involved in the development of obesity and associatedcomorbidities in this model. Methods: Four month old, male WNIN/Ob lean and obese rats were taken, blood was collected and tissues were dissected. Body composition analysis and adipose tissue histology were performed. Global gene expression in retroperitoneal adipose tissue of lean and obese rats was studied by microarray using Affymetrix GeneChips. Results: One thousand and seventeen probe sets were downregulated and 963 probe sets were upregulated (more than two-fold) in adipose tissue of WNIN/Ob obese rats when compared to that of lean rats. Small nucleolar RNA (SnoRNA) made most of the underexpressed probe sets, whereas immune system-related genes werethe most overexpressed in the adipose tissues of obese rats. Genes coding for cytoskeletal proteinswere downregulated, whereas genes related to lipid biosynthesis were elevated in the adipose tissue of obese rats. Interpretation & conclusions: Majority of the altered genes and pathways in adipose tissue of WNIN/Ob obese rats were similar to the observations in other obese animal models and human obesity. Based on these observations, it is proposed that WNIN/Ob obese rat model may be a good model to study the mechanisms involved in the development of obesity and its comorbidities. Downregulation of SnoRNA appears to be a novel feature in this obese rat model. PMID:28139540

  1. VizieR Online Data Catalog: Deep Chandra obs. of the giant HII region N11 in LMC (Naze+, 2014)

    NASA Astrophysics Data System (ADS)

    Naze, Y.; Wang, Q. D.; Chu, Y.-H.; Gruendl, R.; Oskinova, L.

    2014-09-01

    The Chandra ACIS-I observations of N11 were made in six separate segments (ObsID 8210, 8469, 8468, 8467, 8470 and 8211) within two months (June-July) in 2007. We found 165 sources in N11: 43 of them were detected with the highest confidence or smallest P value in the S band (soft 0.5-2keV), 5 in the H band (hard 2-8keV), and 117 in the T band (total 0.5-8keV). We further used Hα, [OIII], and [SII] images taken with the MOSAIC camera on the Blanco 4m Telescope at the Cerro Tololo Inter-American Observatory. The [OIII]λ5007 observations and the [SII]6716,6731 observations consist of four dithered 450s exposures for each location; these images were obtained on 2011 October 31. We have also used infrared observations made with the Spitzer Space Telescope from Gruendl & Chu (2009, Cat. J/ApJS/184/172). (3 data files).

  2. OB3D, a new set of 3D objects available for research: a web-based study

    PubMed Central

    Buffat, Stéphane; Chastres, Véronique; Bichot, Alain; Rider, Delphine; Benmussa, Frédéric; Lorenceau, Jean

    2014-01-01

    Studying object recognition is central to fundamental and clinical research on cognitive functions but suffers from the limitations of the available sets that cannot always be modified and adapted to meet the specific goals of each study. We here present a new set of 3D scans of real objects available on-line as ASCII files, OB3D. These files are lists of dots, each defined by a triplet of spatial coordinates and their normal that allow simple and highly versatile transformations and adaptations. We performed a web-based experiment to evaluate the minimal number of dots required for the denomination and categorization of these objects, thus providing a reference threshold. We further analyze several other variables derived from this data set, such as the correlations with object complexity. This new stimulus set, which was found to activate the Lower Occipital Complex (LOC) in another study, may be of interest for studies of cognitive functions in healthy participants and patients with cognitive impairments, including visual perception, language, memory, etc. PMID:25339920

  3. VizieR Online Data Catalog: RIOTS4: spectroscopic survey of SMC field OB stars (Lamb+, 2016)

    NASA Astrophysics Data System (ADS)

    Lamb, J. B.; Oey, M. S.; Segura-Cox, D. M.; Graus, A. S.; Kiminki, D. C.; Golden-Marx, J. B.; Parker, J. W.

    2016-04-01

    Runaways and Isolated O-Type Star Spectroscopic Survey of the SMC (RIOTS4) targets a spatially complete sample of 374 uniformly selected candidate field OB stars in the SMC. Our targets are identified by Oey et al. (2004, J/AJ/127/1632). We observed the RIOTS4 survey targets over a five-year period from 2006 September to 2011 October using spectrographs on the Magellan telescopes at Las Campanas Observatory. The majority of our observations were obtained with the Inamori-Magellan Areal Camera and Spectrograph (IMACS) in the f/4 multi-slit mode on the Magellan Baade telescope (slit widths of either 0.7" or 1.0", yielding spectral resolutions of R~3700 and R~2600, respectively). With IMACS f/4 out of commission during our 2011 observations, we also operated IMACS in f/2 mode (we used either a 0.5" or 0.7" slit width, which yield spectral resolutions of R~1000 and R~1300, respectively). The remaining targets were observed using the Magellan Inamori Kyocera Echelle (MIKE) Spectrograph on the Magellan Clay telescope (R~28000). All MIKE observations occurred in 2010 November. (2 data files).

  4. OB CITY–Definition of a Family-Based Intervention for Childhood Obesity Supported by Information and Communication Technologies

    PubMed Central

    Hu, Ruofei; Cancela, Jorge; Cea, Gloria; Vlachopapadopoulou, Elpis-Athina; Fotiadis, Dimitrios I.; Fico, Giuseppe

    2016-01-01

    Childhood obesity is becoming one of the 21st century’s most important public health problems. Nowadays, the main treatment of childhood obesity is behavior intervention that aims at improve children’s lifestyle to arrest the disease. Information and communication technologies (ICTs) have not been widely employed in this intervention, and most of existing ICTs systems are not having a long-term effect. The purpose of this paper is to define a system to support family-based intervention through a state-of-the-art analysis of family-based interventions and related technological solutions first, and then using the analytic hierarchy process to derive a childhood obesity family-based behavior intervention model, and finally to provide a prototype of a system called OB CITY. The system makes use of applied behavior analysis, affective computing technologies, as well as serious game and gamification techniques, to offer long term services in all care dimensions of the family-based behavioral intervention aiming to provide positive effects to the treatment of childhood obesity. PMID:27602306

  5. A Wide-Field Narrowband Optical Survey of the Braid Nebula Star Formation Region in Cygnus OB7

    NASA Astrophysics Data System (ADS)

    Magakian, Tigran Yu.; Nikogossian, Elena H.; Aspin, Colin; Pyo, Tae-Soo; Khanzadyan, Tigran; Movsessian, Tigran; Smith, Michael D.; Mitchison, Sharon; Davis, Chris J.; Beck, Tracy L.; Moriarty-Schieven, Gerald H.

    2010-03-01

    We study the population of Herbig-Haro (HH) flows and jets in an area of Cygnus OB7 designated the Braid Nebula star formation region. This complex forms part of the L 1003 dark cloud, and hosts two FU Orionis (FUor)-like objects as well as several other active young stars. To trace outflow activity and to relate both known and newly discovered flows to young star hosts we intercompare new, deep, narrowband Hα and [S II] optical images taken on the Subaru 8 m Telescope on Mauna Kea, Hawaii. Our images show that there is considerable outflow and jet activity in this region suggesting the presence of an extensive young star population. We confirm that both of the FUor-like objects drive extensive HH flows and document further members of the flows in both objects. The L 1003 star formation complex is a highly kinematically active region with young stars in several different stages of evolution. We trace collimated outflows from numerous young stars although the origin of some HH objects remains elusive. Based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

  6. CSO Bolocam 1.1 mm Continuum Mapping of the Braid Nebula Star Formation Region in Cygnus OB7

    NASA Astrophysics Data System (ADS)

    Aspin, Colin; Beck, Tracy L.; Davis, Chris J.; Froebrich, Dirk; Khanzadyan, Tigran; Magakian, Tigran Yu.; Moriarty-Schieven, Gerald H.; Movsessian, Tigran A.; Mitchison, Sharon; Nikogossian, Elena G.; Pyo, Tae-Soo; Smith, Michael D.

    2011-04-01

    We present a 1.1 mm map of the Braid Nebula star formation region in Cygnus OB7 taken using Bolocam on the Caltech Submillimeter Observatory. Within the 1 deg2 covered by the map, we have detected 55 cold dust clumps all of which are new detections. A number of these clumps are coincident with IRAS point sources although the majority are not. Some of the previously studied optical/near-IR sources are detected at 1.1 mm. We estimate total dust/gas masses for the 55 clumps together with peak visual extinctions. We conclude that over the whole region, approximately 20% of the clumps are associated with IRAS sources suggesting that these are protostellar objects. The remaining 80% are classed as starless clumps. In addition, both FU Orionis (FUor) like objects in the field, the Braid Star and HH 381 IRS, are associated with strong millimeter emission. This implies that FUor eruptions can occur at very early stages of pre-main-sequence life. Finally, we determine that the cumulative clump mass function for the region is very similar to that found in both the Perseus and ρ Ophiuchus star-forming regions.

  7. Virio- and bacterioplankton in the estuary zone of the Ob River and adjacent regions of the Kara Sea shelf

    NASA Astrophysics Data System (ADS)

    Kopylov, A. I.; Sazhin, A. F.; Zabotkina, E. A.; Romanenko, A. V.; Romanova, N. D.

    2017-01-01

    The distribution of structural and functional characteristics of virioplankton in the north of the Ob River estuary and the adjacent Kara Sea shelf (between latitudes 71°44'44″ N and 73°45'24″ N) was studied with consideration of the spatial variations in the number ( N B) and productivity ( P B) of bacteria and water properties (temperature, salinity, density) by analyzing samples taken in September 2013. The number of plankton viruses ( N V), the occurrence of visible infected bacteria cells, virus-induced mortality of bacteria, and virioplankton production in the studied region varied within (214-2917) × 103 particles/mL, 0.3-5.6% of NB, 2.2-64.4% of P B, and (6-17248) × 103 particles/(mL day), respectively. These parameters were the highest in water layers with a temperature of +7.3-7.5°C, salinity of 3.75-5.41 psu, and conventional density (στ) of 2.846-4.144. The number of bacterioplankton was (614-822) × 103 cells/mL, and the N V/ N B ratio was 1.1-4.5. A large amount of virus particles were attached to bacterial cells and suspended matter. The data testify to the considerable role of viruses in controlling the number and production of heterotrophic bacterioplankton in the interaction zone of river and sea waters.

  8. CHARA/MIRC observations of two M supergiants in Perseus OB1: Temperature, bayesian modeling, and compressed sensing imaging

    SciTech Connect

    Baron, F.; Monnier, J. D.; Anderson, M.; Aarnio, A.; Kiss, L. L.; Neilson, H. R.; Zhao, M.; Pedretti, E.; Thureau, N.; Ten Brummelaar, T. A.; Sturmann, J.; Sturmann, L.; Turner, N.; Ridgway, S. T.; McAlister, H. A.

    2014-04-10

    Two red supergiants (RSGs) of the Per OB1 association, RS Per and T Per, have been observed in the H band using the Michigan Infra-Red Combiner (MIRC) instrument at the CHARA array. The data show clear evidence of a departure from circular symmetry. We present here new techniques specially developed to analyze such cases, based on state-of-the-art statistical frameworks. The stellar surfaces are first modeled as limb-darkened disks based on SATLAS models that fit both MIRC interferometric data and publicly available spectrophotometric data. Bayesian model selection is then used to determine the most probable number of spots. The effective surface temperatures are also determined and give further support to the recently derived hotter temperature scales of RSGs. The stellar surfaces are reconstructed by our model-independent imaging code SQUEEZE, making use of its novel regularizer based on Compressed Sensing theory. We find excellent agreement between the model-selection results and the reconstructions. Our results provide evidence for the presence of near-infrared spots representing about 3%-5% of the stellar flux.

  9. OB CITY-Definition of a Family-Based Intervention for Childhood Obesity Supported by Information and Communication Technologies.

    PubMed

    Hu, Ruofei; Cancela, Jorge; Arredondo Waldmeyer, Maria Teresa; Cea, Gloria; Vlachopapadopoulou, Elpis-Athina; Fotiadis, Dimitrios I; Fico, Giuseppe

    2016-01-01

    Childhood obesity is becoming one of the 21st century's most important public health problems. Nowadays, the main treatment of childhood obesity is behavior intervention that aims at improve children's lifestyle to arrest the disease. Information and communication technologies (ICTs) have not been widely employed in this intervention, and most of existing ICTs systems are not having a long-term effect. The purpose of this paper is to define a system to support family-based intervention through a state-of-the-art analysis of family-based interventions and related technological solutions first, and then using the analytic hierarchy process to derive a childhood obesity family-based behavior intervention model, and finally to provide a prototype of a system called OB CITY. The system makes use of applied behavior analysis, affective computing technologies, as well as serious game and gamification techniques, to offer long term services in all care dimensions of the family-based behavioral intervention aiming to provide positive effects to the treatment of childhood obesity.

  10. VizieR Online Data Catalog: RVs & V-band LCs of probable members of Cyg OB2 (Kiminki+, 2015)

    NASA Astrophysics Data System (ADS)

    Kiminki, D. C.; Kobulnicky, H. A.; Vargas Alvarez, C. A.; Alexander, M. J.; Lundquist, M. J.

    2016-01-01

    Optical spectroscopic observations of the four targets were obtained as part of the Cygnus OB2 Radial Velocity Survey on numerous dates between 2001 and 2011 using a variety of telescopes and instruments as described in Papers I-IV (see References section below) of this series. Several additional observations were obtained in 2012 October (on MT91 696 and Schulte 3) and 2013 May-June (on MT91 372) using the Wyoming Infrared Observatory (WIRO). Photometry of MT91 696 was obtained on nine nights between 2012 October 17 and November 10 at the University of Wyoming 0.6m Red Buttes Observatory (RBO). Data on Schulte 3 was obtained on 14 nights at RBO between 2012 October 17 and December 21, and data on CPR2002 A36 was obtained on four nights between 2012 December 10 and 22. Photometry of MT91 372 was also obtained at RBO on seven nights between 2013 June 14 and July 8. (6 data files).

  11. A WIDE-FIELD NARROWBAND OPTICAL SURVEY OF THE BRAID NEBULA STAR FORMATION REGION IN CYGNUS OB7

    SciTech Connect

    Magakian, Tigran Yu.; Nikogossian, Elena H.; Movsessian, Tigran; Aspin, Colin; Pyo, Tae-Soo; Khanzadyan, Tigran; Smith, Michael D.; Mitchison, Sharon; Davis, Chris J.; Beck, Tracy L.; Moriarty-Schieven, Gerald H. E-mail: elena@bao.sci.am E-mail: pyo@subaru.naoj.org E-mail: smm23@kent.ac.uk E-mail: c.davis@jach.hawaii.edu E-mail: gerald.schieven@nrc-cnrc.gc.ca

    2010-03-15

    We study the population of Herbig-Haro (HH) flows and jets in an area of Cygnus OB7 designated the Braid Nebula star formation region. This complex forms part of the L 1003 dark cloud, and hosts two FU Orionis (FUor)-like objects as well as several other active young stars. To trace outflow activity and to relate both known and newly discovered flows to young star hosts we intercompare new, deep, narrowband H{alpha} and [S II] optical images taken on the Subaru 8 m Telescope on Mauna Kea, Hawaii. Our images show that there is considerable outflow and jet activity in this region suggesting the presence of an extensive young star population. We confirm that both of the FUor-like objects drive extensive HH flows and document further members of the flows in both objects. The L 1003 star formation complex is a highly kinematically active region with young stars in several different stages of evolution. We trace collimated outflows from numerous young stars although the origin of some HH objects remains elusive.

  12. A Hectochelle Radial Velocity Survey of Cep OB3b: An ONC like cluster at late gas dispersal phase

    NASA Astrophysics Data System (ADS)

    Karnath, Nicole; Allen, Thomas; Prchlik, Jakub; Gutermuth, Robert A.; Megeath, Samuel Thomas; Pipher, Judith; Wolk, Scott J.

    2016-01-01

    Cep OB3b is a young (~3-5 Myr), late gas dispersal cluster of roughly 3000 members broken into two sub-clusters (Eastern and Western) at a distance of 700pc; it is a rare example of nearby cluster in the late stages of gas dispersal and appears to be a more evolved analog to the Orion Nebular Cluster. As part of an ongoing multi wavelength study, we focus on Hectochelle data from the MMT to measure the radial velocities of 499 stars. After removing binaries, outliers, and imposing a minimum R value to the cross correlation, we obtain radial velocities of 57 previously identified members, with an average error of 1.7 km/s. There is no observed variation in radial velocity across the cluster in right ascension or declination. The preferred mechanism for this type of kinematic evolution is that any initial kinematic structure from formation may have been erased and that minimal or no rotation is present in the cluster. However, the Eastern sub-cluster, containing the most massive star in the field, an O7 star, has a higher velocity dispersion than the Western sub-cluster, which contains several B stars. We will compare these results to CO maps of the residual gas in the cluster and discuss possible reasons for this difference. Finally, we will assess whether the cluster is bound or in a state of expansion.

  13. Extinctions and Distances to Dark Clouds from 2MASS, MegaCam and IPHAS Surveys: LDN 1525 in the Direction of the Aur OB1 Association

    NASA Astrophysics Data System (ADS)

    Straižys, V.; Drew, J. E.; Laugalys, V.

    The possibility of applying photometry from the 2MASS J, H, Ks, MegaCam u, g and IPHAS r, i, Hα surveys for determining the distance to the dark cloud LDN 1525 (TGU 1192) in the direction of the Aur OB1 association is investigated using the red clump giants. The main dust cloud, probably related to the emission nebulae Sh 2-232, Sh 2-233, Sh 2-235, the molecular cloud and the association Aur OB2, is found to be located at a distance of 1.3 kpc from the Sun. The nebula Sh 2-231 can be an object of the Perseus arm. The maximum extinction AV found in the cloud is close to 6 mag.

  14. Shear wave splitting observations across the Juan de Fuca plate system: Ridge- to-trench constraints on mantle flow from 2 years of Cascadia Initiative OBS data

    NASA Astrophysics Data System (ADS)

    Bodmer, M.; Toomey, D. R.; Hooft, E. E. E.

    2014-12-01

    We present SKS splitting measurements for the first two years of data collected by the Cascadia Initiative (CI) amphibious array. Our analysis includes observations from over 100 ocean bottom seismometers (OBS), as well as 31 onshore stations, and spans both the Juan de Fuca and Gorda plates. The CI dataset is unique in that it includes several regions that can distinctly influence anisotropic fabric development such as: the upwelling mantle beneath the Juan de Fuca and Gorda ridges, the young evolving oceanic lithosphere of the plate interior, the Blanco transform fault, and the Cascadia subduction zone. For the first time, we are able to analyze these regions with a single dataset, and using a common methodology. Splitting measurements are routinely done on land sites, but have been completed on relatively few OBS stations. This is largely due to the low signal to noise present in OBS data, which can obscure the splitting results. To address that nearly all the OBS data exceeds the global high noise limit at the frequencies used for splitting, we implement a rigorous quality control scheme. Our method specifically takes into account the response of common splitting methods to high noise data and addresses known issues such as cycle skipping, false minima, low transverse energy, and near-null measurements. Individual measurements are filtered at 0.03-0.1 Hz, manually checked for quality, and stacked. Preliminary results show trench perpendicular onshore measurements consistent with previous studies. Oceanic measurements in the plate interior show a coherent fast axis roughly aligned with absolute plate motion. Several measurements near the ridge and trench appear to be rotated in the ridge and trench parallel directions. Continuing work will integrate splitting measurements from the final two years of the CI with these findings, which will be used to characterize the ridge-to-trench mantle flow across the Juan de Fuca plate system.

  15. The initial mass function for massive stars in the Magellanic Clouds. 1: UBV photometry and color-magnitude diagrams for 14 OB associations

    NASA Technical Reports Server (NTRS)

    Hill, Robert J.; Madore, Barry F.; Freedman, Wendy L.

    1994-01-01

    UBV charge coupled device (CCD) photometry has been obtained for 14 OB associations in the Magellanic Clouds using the University of Toronto's 0.6 m telescope and the Carnegie Institution of Washington's 1.0 m reflector, both on Las Campanas, Chile. The data are presented and used to construct color-magnitude diagrams for the purposes of investigating the massive-star content of the associations.

  16. Enhancing the Quality of Service for Real Time Traffic over Optical Burst Switching (OBS) Networks with Ensuring the Fairness for Other Traffics.

    PubMed

    Al-Shargabi, Mohammed A; Shaikh, Asadullah; Ismail, Abdulsamad S

    2016-01-01

    Optical burst switching (OBS) networks have been attracting much consideration as a promising approach to build the next generation optical Internet. A solution for enhancing the Quality of Service (QoS) for high priority real time traffic over OBS with the fairness among the traffic types is absent in current OBS' QoS schemes. In this paper we present a novel Real Time Quality of Service with Fairness Ratio (RT-QoSFR) scheme that can adapt the burst assembly parameters according to the traffic QoS needs in order to enhance the real time traffic QoS requirements and to ensure the fairness for other traffic. The results show that RT-QoSFR scheme is able to fulfill the real time traffic requirements (end to end delay, and loss rate) ensuring the fairness for other traffics under various conditions such as the type of real time traffic and traffic load. RT-QoSFR can guarantee that the delay of the real time traffic packets does not exceed the maximum packets transfer delay value. Furthermore, it can reduce the real time traffic packets loss, at the same time guarantee the fairness for non real time traffic packets by determining the ratio of real time traffic inside the burst to be 50-60%, 30-40%, and 10-20% for high, normal, and low traffic loads respectively.

  17. Identifying Massive Runaway Stars by Detecting Infrared Bowshock Nebula: Four OB Stars and a New Massive Early-B Binary System

    NASA Astrophysics Data System (ADS)

    Sorber, Rebecca L.; Rebecca L. Sorber, Henry A. Kobulnicky, Daniel A. Dale, Matthew S. Povich, William T. Chick, Heather N. Wernke, Julian E. Andrews, Stephan Munari, Grace M. Olivier, Danielle Schurhammer

    2016-01-01

    Though the main sequence evolution of OB type stars is relatively well known, the mass loss rates for these stars are still highly uncertain. Some OB stars are gravitationally ejected from their birth sites, traveling at speeds of 30 km/s or more which results in a prominent bowshock nebulae. We identified OB bowshock candidates at low Galactic latitudes by visual inspection of the Wide-field Infrared Survey Explorer (WISE) 22-micron images. Each candidate was observed using the Longslit Spectrograph at the Wyoming Infrared Observatory (WIRO) 2.3 meter telescope. We present here the results from observing four such candidates, and all four are confirmed as early type stars: GO92.3191+0.0591 (B1V) (aka ALS11826), GO86.551014-1.0873935 (B2V; a probable short-period binary), G076.6921-2.4071 (B5V), and G075.5711-0.2558 (B0V) (aka HD 194303). These results enlarge the sample of candidate runaway massive stars hosting bowshocks and provide a promising sample of such objects for studying stellar mass loss. This work is supported by the National Science Foundation Grants AST-1063146 (REU), AST-1411851 (RUI), and AST-1412845.

  18. TRC120038, a Novel Dual AT1/ETA Receptor Blocker for Control of Hypertension, Diabetic Nephropathy, and Cardiomyopathy in ob-ZSF1 Rats

    PubMed Central

    Mohanan, Anookh; Gupta, Ram; Dubey, Amita; Jagtap, Vikrant; Mandhare, Appaji; Gupta, Ramesh C.; Chauthaiwale, Vijay; Dutt, Chaitanya

    2011-01-01

    In hypertensive subjects, angiotensin II and endothelin participate in a manner involving closely interwoven pathways in increasing blood pressure (BP) and inducing end organ damage. The primary objective of this study was to determine the effect of TRC120038, a novel dual AT1/ETA receptor blocker on BP, in obese Zucker spontaneously hypertensive fatty rats (ob-ZSF1), an animal model of moderate hypertension, diabetes with progressive renal and cardiac dysfunction. Ob-ZSF1 rats loaded with 0.5% salt were treated with TRC120038 (11.8 mg/kg bid.) or candesartan cilexetil (0.3 mg/kg od.) or vehicle control. Blood pressure (by radio-telemetry) and renal functional markers were monitored throughout the study. Cardiac function was assessed terminally by pressure volume catheter. Markers for renal dysfunction were measured and changes were evaluated histopathologically. TRC120038 showed greater fall in both systolic and diastolic BP in comparison to candesartan at its maximum antihypertensive dose. TRC120038 also reduced the severity of renal dysfunction and preserved cardiac function in ob-ZSF1 rat. PMID:22235363

  19. Methylosinus trichosporium OB3b Mutants Having Constitutive Expression of Soluble Methane Monooxygenase in the Presence of High Levels of Copper

    PubMed Central

    Phelps, Patricia A.; Agarwal, Sandeep K.; Speitel, Gerald E.; Georgiou, George

    1992-01-01

    The methanotrophic bacterium Methylosinus trichosporium OB3b is unusually active in degrading recalcitrant haloalkanes such as trichloroethylene (TCE). The first and rate-limiting step in the degradation of TCE is catalyzed by a soluble methane monooxygenase (sMMO). This enzyme is not expressed when the cells are grown in the presence of copper at concentrations typically found in polluted groundwater. Under these conditions, M. trichosporium OB3b expresses a particulate form of the enzyme (pMMO), which has a narrow substrate specificity and does not degrade TCE at any significant rate. We have isolated M. trichosporium OB3b mutants that are deficient in pMMO and express sMMO constitutively in the presence of elevated concentrations of copper. One mutant (PP358) exhibited a TCE degradation rate which was almost twice as high as that of the wild-type strain grown under optimal conditions (without copper). All of the mutants lost the ability to express pMMO activity and to form stacked intracellular membranes characteristic of wild-type cells expressing pMMO. Images PMID:16348810

  20. Role of NAD+-Dependent Malate Dehydrogenase in the Metabolism of Methylomicrobium alcaliphilum 20Z and Methylosinus trichosporium OB3b

    PubMed Central

    Rozova, Olga N.; Khmelenina, Valentina N.; Bocharova, Ksenia A.; Mustakhimov, Ildar I.; Trotsenko, Yuri A.

    2015-01-01

    We have expressed the l-malate dehydrogenase (MDH) genes from aerobic methanotrophs Methylomicrobium alcaliphilum 20Z and Methylosinus trichosporium OB3b as his-tagged proteins in Escherichia coli. The substrate specificities, enzymatic kinetics and oligomeric states of the MDHs have been characterized. Both MDHs were NAD+-specific and thermostable enzymes not affected by metal ions or various organic metabolites. The MDH from M. alcaliphilum 20Z was a homodimeric (2 × 35 kDa) enzyme displaying nearly equal reductive (malate formation) and oxidative (oxaloacetate formation) activities and higher affinity to malate (Km = 0.11 mM) than to oxaloacetate (Km = 0.34 mM). The MDH from M. trichosporium OB3b was homotetrameric (4 × 35 kDa), two-fold more active in the reaction of oxaloacetate reduction compared to malate oxidation and exhibiting higher affinity to oxaloacetate (Km = 0.059 mM) than to malate (Km = 1.28 mM). The kcat/Km ratios indicated that the enzyme from M. alcaliphilum 20Z had a remarkably high catalytic efficiency for malate oxidation, while the MDH of M. trichosporium OB3b was preferable for oxaloacetate reduction. The metabolic roles of the enzymes in the specific metabolism of the two methanotrophs are discussed. PMID:27682078

  1. The Herschel/PACS view of the Cep OB2 region: Global protoplanetary disk evolution and clumpy star formation

    NASA Astrophysics Data System (ADS)

    Sicilia-Aguilar, Aurora; Roccatagliata, Veronica; Getman, Konstantin; Rivière-Marichalar, Pablo; Birnstiel, Tilman; Merín, Bruno; Fang, Min; Henning, Thomas; Eiroa, Carlos; Currie, Thayne

    2015-01-01

    Context. The Cep OB2 region, with its two intermediate-aged clusters Tr 37 and NGC 7160, is a paradigm of sequential star formation and an ideal site for studies of protoplanetary disk evolution. Aims: We use Herschel data to study the protoplanetary disks and the star formation history of the region. Methods: Herschel/PACS observations at 70 and 160 μm probe the disk properties (mass, dust sizes, structure) and the evolutionary state of a large number of young stars. Far-IR data also trace the remnant cloud material and small-scale cloud structure. Results: We detect 95 protoplanetary disks at 70 μm, 41 at 160 μm, and obtain upper limits for more than 130 objects. The detection fraction at 70 μm depends on the spectral type (88% for K4 or earlier stars, 17% for M3 or later stars) and on the disk type (~50% for full and pre-transitional disks, ~35% for transitional disks, no low-excess/depleted disks detected). Non-accreting disks are not detected, suggesting significantly lower masses. Accreting transition and pre-transition disks have systematically higher 70 μm excesses than full disks, suggestive of more massive, flared and/or thicker disks. Herschel data also reveal several mini-clusters in Tr 37, which are small, compact structures containing a few young stars surrounded by nebulosity. Conclusions: Far-IR data are an excellent probe of the evolution of disks that are too faint for sub-millimetre observations. We find a strong link between far-IR emission and accretion, and between the inner and outer disk structure. Herschel confirms the dichotomy between accreting and non-accreting transition disks. Accretion is a powerful measure of global disk evolution: substantial mass depletion and global evolution need to occur to shut down accretion in a protoplanetary disk, even if the disk has inner holes. Disks likely follow different evolutionary paths: low disk masses do not imply opening inner holes, and having inner holes does not require low disk masses

  2. B fields in OB stars (BOB): Low-resolution FORS2 spectropolarimetry of the first sample of 50 massive stars

    NASA Astrophysics Data System (ADS)

    Fossati, L.; Castro, N.; Schöller, M.; Hubrig, S.; Langer, N.; Morel, T.; Briquet, M.; Herrero, A.; Przybilla, N.; Sana, H.; Schneider, F. R. N.; de Koter, A.; BOB Collaboration

    2015-10-01

    Within the context of the collaboration "B fields in OB stars" (BOB), we used the FORS2 low-resolution spectropolarimeter to search for a magnetic field in 50 massive stars, including two reference magnetic massive stars. Because of the many controversies of magnetic field detections obtained with the FORS instruments, we derived the magnetic field values with two completely independent reduction and analysis pipelines. We compare and discuss the results obtained from the two pipelines. We obtained a general good agreement, indicating that most of the discrepancies on magnetic field detections reported in the literature are caused by the interpretation of the significance of the results (i.e., 3-4σ detections considered as genuine, or not), instead of by significant differences in the derived magnetic field values. By combining our results with past FORS1 measurements of HD 46328, we improve the estimate of the stellar rotation period, obtaining P = 2.17950 ± 0.00009 days. For HD 125823, our FORS2 measurements do not fit the available magnetic field model, based on magnetic field values obtained 30 years ago. We repeatedly detect a magnetic field for the O9.7V star HD 54879, the HD 164492C massive binary, and the He-rich star CPD -57 3509. We obtain a magnetic field detection rate of 6 ± 4%, while by considering only the apparently slow rotators we derive a detection rate of 8 ± 5%, both comparable with what was previously reported by other similar surveys. We are left with the intriguing result that, although the large majority of magnetic massive stars is rotating slowly, our detection rate is not a strong function of the stellar rotational velocity. Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under programme ID 191.D-0255(A, C).

  3. Measuring the rotation periods of 4-10 Myr T-Tauri stars in the Orion OB1 association

    NASA Astrophysics Data System (ADS)

    Karim, Md Tanveer; Stassun, Keivan; Briceno, Cesar; Vivas, Kathy; Raetz, Stefanie; Calvet, Nuria; Mateu, Cecilia; Downes, Juan Jose; Hernandez, Jesus; Neuhäuser, Ralph; Mugrauer, Markus; Takahashi, Hidenori; Tachihara, Kengo; Chini, Rolf; YETI

    2016-01-01

    Most existing studies of young stellar populations have focused on the youngest (< 2-3 Myr) T-Tauri stars, which are usually associated with their natal gas and hence easier to identify. In contrast, older T-Tauri stars (~ 4-10 Myr), being more difficult to find, have been less studied, even though they hold key insight to understanding evolution of lower-mass (0.1-2 M⊙) stars and of protoplanetary discs. We present a study of photometric variability of 1974 confirmed 4-10 Myr old T-Tauri stars in the Orion OB1 association using optical time-series from three different surveys: the Centro de Investigaciones de Astronomía-Quest Equatorial Survey Team (CIDA-QUEST), the Young Exoplanet Transit Initiative (YETI) and from a Kitt Peak National Observatory (KPNO) campaign. We investigated stellar rotation periods according to the type of stars (Classical or Weak-lined T-Tauri stars) and their locations, to look for population-wide trends. We detected 563 periodic variables and 1411 non-periodic variables by investigating the light curves of these stars. We find that ~ 30% of Weak-line T-Tauri stars (WTTS) and ~ 20% of Classical T-Tauri stars (CTTS) are periodic. Though we did not find any noticeable difference in rotation period between CTTS and WTTS, our study does show a change in the overall rotation periods of stars 4-10 Myr old, consistent with predictions of angular momentum evolution models, an important constraint for theoretical models for an age range for which no similar data existed.

  4. Injection-attachment of Methylosinus trichosporium OB3b in a two-dimensional miniature sand-filled aquifer simulator

    NASA Astrophysics Data System (ADS)

    Shonnard, D. R.; Taylor, R. T.; Hanna, M. L.; Boro, C. O.; Duba, A. G.

    1994-01-01

    For some potentially useful and emerging in situ bioremediation technologies it is important to control bacterial attachment to subsurface materials during the injection of microbial cell suspensions. In this study the attachment patterns of Methylosinus trichosporium OB3b were measured after horizontal injections into a two-dimensional miniature aquifer simulator containing a wet homogeneous sand. In preliminary sand column assays, bacterial attachment to the sand was increased nearly 2 orders of magnitude compared to attachment in the presence of distilled water by raising the concentration of a pH 7.0 sodium-potassium phosphate buffer to 10 mM. The maximal concentration of attached cells was ˜4×108 cells/g dry sand with both sand minicolumns and the wet sand aquifer simulator. For the latter this occurred on streamlines directly between the horizontal injector and withdrawal ports, where injection-withdrawal velocities were the highest. The effects of a simulated groundwater cross flow during suspension injection on bacterial attachment to the aquifer simulator sands were also studied, and a peristaltic pumping method to counteract these groundwater flow effects resulted in a more localized pattern, i.e., without extensive downstream skewing of the bacterial attachment zone. Phenol red was utilized as a nonbinding, red-colored tracer compound. It proved to be very convenient for quantitatively measuring the earlier breakthroughs of cells versus an inert tracer during the aquifer simulator and subsequent capillary tube cell injection experiments and also for visualizing the anticipated boundaries of cell attachment in the aquifer simulator. The effect of injection velocity on the observed bacterial attachment patterns in these experiments appears to be accounted for by colloid filtration theory.

  5. Far-Ultraviolet Study in the Ophiuchus cloud complex and the Upper Scorpius subgroup of the Sco OB2 association

    NASA Astrophysics Data System (ADS)

    Lim, Taeho; Min, K.; Seon, K.

    2014-01-01

    We have constructed a far-ultraviolet (FUV) continuum map and a molecular hydrogen fluorescent map of the Ophiuchus cloud complex, one of a well-known birthplace of stars using FUV Imaging Spectrograph (FIMS). The FUV intensity varies significantly across the whole region. FUV flux is bright on Sco OB2 association where Hα emission is also bright, while FUV flux seems to be heavily absorbed by the dense cloud of rho-Ophiuchus cloud, where the dust extinction level is high. It seems that molecular hydrogen fluorescence correlates well with CO emission throughout whole region. Dust extinction also shows a relationship with molecular hydrogen fluorescence. Using the result of interstellar radiation field calculation, we found that fluorescence in this region is likely to depend more on abundance of molecular hydrogen, directly connected to dust extinction. We also found that the H2 fluorescent emission for a certain PDR has a log-normal distribution. We also showed that Interstellar radiation field also can be log-normally distributed. Based on star catalog and stellar model, we calculate interstellar radiation field up to 1kpc from the Sun. At the Sun, the ISRF was ~1.6 G0 when the extinction was considered while it was ~5.4 G0 without the extinction effect on ISRF. We also applied this result of ISRF calculation to two kinds of studies: (1) determination of cloud distance and (2) parameter constraint in PDR simulation. As a line of research to understand spatial characteristics of molecular hydrogen fluorescence in this region, we present the result of PDR simulations using CLOUD for some individual regions that are suspected of PDRs (Photodissociation Regions).

  6. Borate mineral assemblages in the system Na2OCaOMgOB2O3H2O

    USGS Publications Warehouse

    Christ, C.L.; Truesdell, A.H.; Erd, Richard C.

    1967-01-01

    he significant known hydrated borate mineral assemblages (principally of the western United States) in the system Na2OCaOz.sbnd;MgOB2O3H2O are expressible in three ternary composition diagrams. Phase rule interpretation of the diagrams is consistent with observation, if the activity of H2O is generally considered to be determined by the geologic environment. The absence of conflicting tie-lines on a diagram indicates that the several mineral assemblages of the diagram were formed under relatively narrow ranges of temperature and pressure. The known structural as well as empirical formulas for the minerals are listed, and the more recent (since 1960) crystal structure findings are discussed briefly. Schematic Gibbs free energy-composition diagrams based on known solubility-temperature relations in the systems Na2B4O7-H2O and Na2B4O7-NaCl-H2O, are highly useful in the interpretation and prediction of the stability relations in these systems; in particular these diagrams indicate clearly that tincalconite, although geologically important, is everywhere a metastable phase. Crystal-chemical considerations indicate that the same thermodynamic and kinetic behavior observed in the Na2B4O7-H2O system will hold in the Ca2B6O11-H2O system. This conclusion is confirmed by the petrologic evidence. The chemical relations among the mineral assemblages of a ternary diagram are expressed by a schematic "activity-activity" diagram. These activity-activity diagrams permit the tracing-out of the paragenetic sequences as a function of changing cation and H2O activities. ?? 1967.

  7. Neutron field measurements of the CRNA OB26 irradiator using a Bonner sphere spectrometer for radiation protection purposes.

    PubMed

    Mazrou, H; Allab, M

    2012-08-01

    The present work deals with the Bonner sphere spectrometer (BSS) measurements performed, to support the authors' Monte-Carlo calculations, to estimate accurately the main characteristics of the neutron field of the (241)Am-Be-based OB26 irradiator acquired for radiation protection purposes by the Nuclear Research Centre of Algiers. The measurements were performed at a reference irradiation position selected at 150 cm from the geometrical centre of the neutron source. The spectrometric system in use is based on a central spherical (3)He thermal neutron proportional counter. The response matrix of the present spectrometer has been taken to be similar to the original Physikalisch-Technische Bundesanstalt (PTB) (Braunschweig, Germany) BSS's response matrix, with a five bins per decade energy group structure, as there is no significant difference in the BSS's physical characteristics. Thereafter, the authors' BSS measurements were used together with MCNP5 results to unfold the neutron spectrum by means of MAXED and GRAVEL computer codes from the U.M.G. 3.3 package, developed at PTB. Besides, sensitivity analysis has been performed to test the consistency of the unfolding procedure. It reveals that no significant discrepancy was observed in the total neutron fluence and total ambient dose values following the perturbation of some pertinent unfolding parameters except for the case where a 10 bins energy structure was assumed for the guess spectrum. In this latter case, a 5 % difference was observed in the ambient dose equivalent compared with the reference case. Finally, a comparative study performed between different counting systems together with MCNP5 and predictive formulas results shows that they were globally satisfactory, highlighting thereby the relevance of the unfolding procedure and the reliability of the obtained results.

  8. Copper complexation of methanobactin isolated from Methylosinus trichosporium OB3b: pH-dependent speciation and modeling.

    PubMed

    Pesch, Marie-Laure; Christl, Iso; Hoffmann, Martin; Kraemer, Stephan M; Kretzschmar, Ruben

    2012-11-01

    Methanobactins are copper-binding ligands produced by aerobic methanotrophic microorganisms. A quantitative understanding of their potential role in methanotrophic copper acquisition requires the investigation of their copper complexes under relevant pH conditions. In this study, a chemical speciation model describing the pH-dependence of copper binding and the formation of the different complexes by methanobactin (mb) is released by Methylosinus trichosporium OB3b was developed. Potentiometric and spectrophotometric titrations of the free ligand indicated the presence of four protonation sites consistent with the molecular structure of methanobactin. Metal titrations revealed a distinct pH-dependence of copper binding to methanobactin between pH 5 and 8. Based on evidence from size-exclusion chromatography coupled to inductively coupled plasma mass spectrometry (ICP-MS), the copper binding was quantitatively described with three different types of copper-methanobactin complexes which can additionally undergo protonation reactions. The high affinity observed upon initial copper additions resulted from the predominant occurrence of copper-methanobactin dimer complexes, mb(2)H(4)Cu and mb(2)H(3)Cu with log K values of 58 and 52, respectively. With increasing copper to methanobactin ratios, methanobactin bound copper as monomers, mbHCu (log K=25) and mbCu (log K=18), whereas at elevated copper activities methanobactin was able to bind two copper ions (mbHCu(2) and mbCu(2)). Model calculations based on the fitted complexation constants suggest that in natural systems, copper-methanobactin complexes are mostly present as monomers.

  9. Input of organic carbon as determinant of nutrient fluxes, light climate and productivity in the Ob and Yenisey estuaries

    NASA Astrophysics Data System (ADS)

    Hessen, Dag O.; Carroll, JoLynn; Kjeldstad, Berit; Korosov, Anton A.; Pettersson, Lasse H.; Pozdnyakov, Dmitry; Sørensen, Kai

    2010-06-01

    Spectral light attenuation profiles and concentrations of total and dissolved carbon (C), nutrients and chlorophyll a (Chl a) were studied along transects running from the river mouth to the Kara Sea during late summer 2003 for the Yenisey and fall 2005 for the Ob estuaries. Earth Observation data were used to generate composite images of water color and Chl a distribution over the estuaries and the Kara Sea to reveal the spatial impact of the river efflux in terms of optical properties. High levels of total nitrogen (N), total phosphorus (P), silicate (Si) and iron (Fe), but low levels of inorganic N and P and Chl a were found in the estuaries. More than 90 % of total organic C was in dissolved form (DOC). The high concentrations of DOC, mostly terrigenous, humic compounds, gave extremely high attenuation coefficients for both visible and ultraviolet light. For UV-B, Z10% (the depth at which 10% of surface light remains) was <10 cm, while Z10% for visible light (PAR) generally ranged between 1 and 3 m for both transects. The light attenuation rapidly decreases when the freshwater is mixed with the coastal water outside off the coast. This leads to a strong light limitation and low productivity in the inner estuaries, while the high load of N and P associated with DOC eventually could promote primary production in the Kara Sea and further upstream the coastal current in the Arctic Ocean as the organic matter becomes diluted and photooxidized. On the other hand, the high inputs of colored dissolved organic matter (CDOM) provide an efficient screening of potential harmful UV-radiation over vast areas of the Arctic Ocean. A rising trend of riverine efflux to the Arctic seas is observed, and further increases in freshwater runoff as well as eventual permafrost thawing, will accentuate the freshwater impact in the estuaries and the Kara Sea.

  10. CONSTRAINTS ON THE MAGELLANIC CLOUDS' INTERACTION FROM THE DISTRIBUTION OF OB STARS AND THE KINEMATICS OF GIANTS

    SciTech Connect

    Casetti-Dinescu, Dana I.; Girard, Terrence M.; Van Altena, William F.; Vieira, Katherine E-mail: terry.girard@yale.edu E-mail: kvieira@cida.ve

    2012-07-10

    Young, OB-type candidates are identified in a {approx}7900 deg{sup 2} region encompassing the Large and Small Magellanic Clouds (LMC/SMC) periphery, the Bridge, part of the Magellanic Stream (MS), and Leading Arm (LA). Selection is based on UV, optical, and IR photometry from existing large-area surveys and proper motions from the Southern Proper Motion 4 (SPM4) catalog. The spatial distribution of these young star candidates shows (1) a well-populated SMC wing which continues westward with two branches partially surrounding the SMC, (2) a rather narrow path from the SMC wing eastward toward the LMC which is offset by 1 Degree-Sign -2 Degree-Sign from the high-density H I ridge in the Bridge, (3) a well-populated periphery of the LMC dominated by clumps of stars at the ends of the LMC bar, and (4) a few scattered candidates in the MS and two overdensities in the LA regions above and below the Galactic plane. Additionally, a proper-motion analysis is made of a radial-velocity-selected sample of red giants and supergiants in the LMC, previously shown to be a kinematically and chemically distinct subgroup, most likely captured from the SMC. SPM4 proper motions of these stars also indicate they are distinct from the LMC population. The observational results presented here, combined with the known orbits of the Clouds and other aspects of the LMC morphology, suggest an off-center, moderate to highly inclined collision between the SMC and the LMC's disk that took place between 100 and 200 Myr ago.

  11. [Modeling of Processes of Migration and Accumulation of Radionuclides in Freshwater Ecosystems by the Example of the Samson, Lev, Vandras Rivers Related to the Ob-Irtysh River Basin].

    PubMed

    Trapeznikov, A V; Korzhavin, A V; Trapeznikova, V N; Nikolkin, V N

    2016-01-01

    Mathematical models of horizontal distribution and migration of radionuclides are presented in water and floodplain soils of the Samson-Lev-Vandras river system related to the Ob-Irtysh river basin. Integral inventory of radionuclides in the main components of the river ecosystems is calculated. The estimated annual discharge of radionuclides from the Vandras river to the Great Salym river is given. The effect of the removal of man-made radionuclides in the Samson, Lev, Vandras rivers on radioactive contamination of the Ob-Irtysh river system is shown in comparison with the Techa river, that also belongs to the Ob-Irtysh river basin. Despite the presence of an additional radioactive contamination of the Samson floodplain, the transfer of radioactive substances in the Samson, Lev, Vandras rivers has a much smaller impact on the contamination of the Ob-Irtysh river system, compared to the Techa river, prone to a large-scale radioactive contamination.

  12. Synthesis and Characterization of Et2NM OB[Si(OtBu)3]2 3 (M=Zr,Hf) Molecular Precursors to Zr/B/Si/O and Hf/B/Si/O Materials

    SciTech Connect

    Fujdala, Kyle L.; Tilley, T. Don

    2005-03-18

    Two new transition metal complexes containing the -OB[OSi(OtBu)3]2 ligand, Et2NM{l_brace}OB[OSi(OtBu)3]2{r_brace}3 (M = Zr, Hf), are reported. These species are the 4th and 5th examples of complexes containing this recently reported borosiloxide ligand. Their use as potential molecular precursors to multi-component oxide materials via the thermolytic molecular precursor (TMP) method is discussed.

  13. Measuring earthquake source parameters in the Mendocino triple junction region using a dense OBS array: Implications for fault strength variations

    NASA Astrophysics Data System (ADS)

    Chen, Xiaowei; McGuire, Jeffrey J.

    2016-11-01

    Subduction zones produce earthquakes on a set of faults that operate under a wide variety of conditions resulting from considerable variations in depth, temperature, rock type, and fluid pressure. These variations likely lead to variation in the stress levels that drives particular earthquakes and that in turn effects the magnitude of seismic shaking they produce. In the Mendocino Triple Junction (MTJ) region, intraplate faults within the mantle of the subducting plate fail regularly in energetic earthquakes while the adjacent thrust interface of the Cascadia subduction zone remains seismically quiet despite the likelihood that it operates at much lower levels of stress and strength. In 2012, as part of the Cascadia Initiative community experiment, an ocean bottom seismometer (OBS) array was deployed in the MTJ area, providing unusually dense data covering both the inter- and intra-plate earthquakes. Combining these data with onshore networks, we detect and relocate 1137 earthquakes with a three dimensional velocity model. We perform detailed spectral and time domain analysis to study variations in earthquake source properties between the different types of faults. We observe a wide variability of stress drops and systematic lateral and depth variations in the earthquake source spectra resulting from the different types of tectonic fault systems in this region: intraplate faults within the subducted oceanic mantle, the Mendocino transform plate boundary fault, and the thrust interface of the Cascadia subduction zone. Some of the depth variability of source spectra can be explained by the expected increase in rupture velocity with depth. However, the overall variation in stress drop estimates is consistent with the highest stress drop earthquakes occurring in the depth range predicted by strength envelopes. Moreover, the earthquakes in the vicinity of the thrust interface, likely including some within the subducted oceanic crust, show clearly lower stress drops and

  14. Pinning fault zone strength using small earthquakes in the Mendocino triple junction region recorded by a dense OBS array

    NASA Astrophysics Data System (ADS)

    Chen, X.; McGuire, J. J.

    2014-12-01

    The Mendocino triple junction contains a diversity of fault types including plate boundary strike-slip and thrust faults as well as intraplate faults within the subducting oceanic mantle that are expected to operate under significantly different rheological conditions. We analyze the data from the Cascadia Initiative's Year-2 focused OBS array deployed at the triple junction region. We detect over 1000 earthquakes with magnitude ranging from 1 to 4.5 from Sep 2012 to Feb 2013. Locations refined with waveform cross-correlation arrival time measurements delineate two sub-parallel faults trending NW-SE revealing the complex geometry of the triple junction, as well as a intraplate fault possibly related to the 2010 M6.5 earthquake in the subducted Gorda plate. We are performing a joint inversion for 3D structure and hypocenter locations to further refine the image of the triple junction fault systems. Our primary focus is on examining earthquake rupture mechanics in this complex fault network. Strength envelope calculations predict that the faults within the subducting Gorda plate support differential stress levels that are 1-2 orders of magnitude larger than what is typically assumed for the thrust interface. To determine if this contrast is reflected in the data, we estimate apparent stress for the M>2 earthquakes on the three types of faults. We compute displacement spectra using 2.56s time window from the picked arrival. Spectra with signal-to-noise ratio > 3 between 4 to 10 Hz are saved for further analysis. For the saved spectra, we apply two approaches using EGF method: (1) single event-pair deconvolution, where we select best-similar event pairs using relative locations derived from waveform cross-correlation, (2) iterative stacking deconvolution, where we solve for a event term, a station term and a path term using all the event-station pairs. Once the target event source spectrum is obtained, we compute the stress drop and apparent stress using the

  15. An eclipsing double-line spectroscopic binary at the stellar/substellar boundary in the Upper Scorpius OB association

    NASA Astrophysics Data System (ADS)

    Lodieu, N.; Alonso, R.; González Hernández, J. I.; Sanchis-Ojeda, R.; Narita, N.; Kawashima, Y.; Kawauchi, K.; Suárez Mascareño, A.; Deeg, H.; Prieto Arranz, J.; Rebolo, R.; Pallé, E.; Béjar, V. J. S.; Ferragamo, A.; Rubiño-Martín, J. A.

    2015-12-01

    Aims: We aim at constraining evolutionary models at low mass and young ages by identifying interesting transiting system members of the nearest OB association to the Sun, Upper Scorpius (USco), which has been targeted by the Kepler mission. Methods: We produced light curves for M-dwarf members of the USco region that has been surveyed during the second campaign of the Kepler K2 mission. We identified by eye a transiting system, USco J161630.68-251220.1 (=EPIC 203710387) with a combined spectral type of M5.25, whose photometric, astrometric, and spectroscopic properties makes it a member of USco. We conducted an extensive photometric and spectroscopic follow-up of this transiting system with a suite of telescopes and instruments to characterise the properties of each component of the system. Results: We calculated a transit duration of about 2.42 h that occurs every 2.88 days with a slight difference in transit depth and phase between the two components. We estimated a mass ratio of 0.922 ± 0.015 from the semi-amplitudes of the radial velocity curves for each component. We derived masses of 0.091 ± 0.005M⊙ and 0.084 ± 0.004M⊙, radii of 0.388 ± 0.008R⊙ and 0.380 ± 0.008R⊙, luminosities of log (L/L⊙) = -2.020-0.121+0.099 dex and -2.032-0.121+0.099 dex, and effective temperatures of 2901-172+199 K and 2908-172+199 K for the primary and secondary, respectively. Conclusions: We present a complete photometric and radial velocity characterisation of the least massive double-line eclipsing binary system in the young USco association with two components close to the stellar/substellar limit. This system falls in a gap between the least massive eclipsing binaries in the low-mass and substellar regimes at young ages and represents an important addition to constraining evolutionary models at young ages. Based on observations made with telescopes (GTC, WHT) installed in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de

  16. X-RAY EMISSION FROM THE DOUBLE-BINARY OB-STAR SYSTEM QZ CAR (HD 93206)

    SciTech Connect

    Parkin, E. R.; Naze, Y.; Rauw, G.; Broos, P. S.; Townsley, L. K.; Pittard, J. M.; Moffat, A. F. J.; Oskinova, L. M.; Waldron, W. L.

    2011-05-01

    X-ray observations of the double-binary OB-star system QZ Car (HD 93206) obtained with the Chandra X-ray Observatory over a period of roughly 2 years are presented. The respective orbits of systems A (O9.7 I+b2 v, P{sub A} = 21 days) and B (O8 III+o9 v, P{sub B} = 6 days) are reasonably well sampled by the observations, allowing the origin of the X-ray emission to be examined in detail. The X-ray spectra can be well fitted by an attenuated three-temperature thermal plasma model, characterized by cool, moderate, and hot plasma components at kT {approx_equal} 0.2, 0.7, and 2 keV, respectively, and a circumstellar absorption of {approx_equal}0.2 x 10{sup 22} cm{sup -2}. Although the hot plasma component could be indicating the presence of wind-wind collision shocks in the system, the model fluxes calculated from spectral fits, with an average value of {approx_equal}7 x 10{sup -13} erg s{sup -1} cm{sup -2}, do not show a clear correlation with the orbits of the two constituent binaries. A semi-analytical model of QZ Car reveals that a stable momentum balance may not be established in either system A or B. Yet, despite this, system B is expected to produce an observed X-ray flux well in excess of the observations. If one considers the wind of the O8 III star to be disrupted by mass transfer, the model and observations are in far better agreement, which lends support to the previous suggestion of mass transfer in the O8 III + o9 v binary. We conclude that the X-ray emission from QZ Car can be reasonably well accounted for by a combination of contributions mainly from the single stars and the mutual wind-wind collision between systems A and B.

  17. Long term photometric monitoring with the Mercator telescope. Frequencies and mode identification of variable O-B stars

    NASA Astrophysics Data System (ADS)

    De Cat, P.; Briquet, M.; Aerts, C.; Goossens, K.; Saesen, S.; Cuypers, J.; Yakut, K.; Scuflaire, R.; Dupret, M.-A.; Uytterhoeven, K.; van Winckel, H.; Raskin, G.; Davignon, G.; Le Guillou, L.; van Malderen, R.; Reyniers, M.; Acke, B.; De Meester, W.; Vanautgaerden, J.; Vandenbussche, B.; Verhoelst, T.; Waelkens, C.; Deroo, P.; Reyniers, K.; Ausseloos, M.; Broeders, E.; Daszyńska-Daszkiewicz, J.; Debosscher, J.; De Ruyter, S.; Lefever, K.; Decin, G.; Kolenberg, K.; Mazumdar, A.; van Kerckhoven, C.; De Ridder, J.; Drummond, R.; Barban, C.; Vanhollebeke, E.; Maas, T.; Decin, L.

    2007-02-01

    Aims: We selected a large sample of O-B stars that were considered as (candidate) slowly pulsating B, β Cep, and Maia stars after the analysis of their hipparcos data. We analysed our new seven passband geneva data collected for these stars during the first three years of scientific operations of the mercator telescope. We performed a frequency analysis for 28 targets with more than 50 high-quality measurements to improve their variability classification. For the pulsating stars, we tried both to identify the modes and to search for rotationally split modes. Methods: We searched for frequencies in all the geneva passbands and colours by using two independent frequency analysis methods and we applied a 3.6 S/N-level criterion to locate the significant peaks in the periodograms. The modes were identified by applying the method of photometric amplitudes for which we calculated a large, homogeneous grid of equilibrium models to perform a pulsational stability analysis. When both the radius and the projected rotational velocity of an object are known, we determined a lower limit for the rotation frequency to estimate the expected frequency spacings in rotationally split pulsation modes. Results: We detected 61 frequencies, among which 33 are new. We classified 21 objects as pulsating variables (7 new confirmed pulsating stars, including 2 hybrid β Cep/SPB stars), 6 as non-pulsating variables (binaries or spotted stars), and 1 as photometrically constant. All the Maia candidates were reclassified into other variability classes. We performed mode identification for the pulsating variables for the first time. The most probable ℓ value is 0, 1, 2, and 4 for 1, 31, 9, and 5 modes, respectively, including only 4 unambiguous identifications. For 7 stars we cannot rule out that some of the observed frequencies belong to the same rotationally split mode. For 4 targets we may begin to resolve close frequency multiplets. Based on observations collected with the p7 photometer

  18. The distribution and history of nuclear weapons related contamination in sediments from the Ob River, Siberia as determined by isotopic ratios of plutonium and neptunium.

    PubMed

    Kenna, T C; Sayles, F L

    2002-01-01

    Isotopic ratios of Pu and Np measured in sediment cores from 5 locations in the Ob River drainage basin show clear evidence of input from sources other than global fallout (non-fallout sources). Historical contaminant records obtained by combining isotopic ratio information with chronological information indicate that non-fallout inputs are from several sources that have varied significantly over the past 50 years. Unique isotopic signatures observed in sediments from tributaries that drain areas containing known or suspected sources of non-fallout contamination are used to identify the source of materials in sediments collected at downstream locations. These data can lead to a better understanding of the transport behavior, fate, and relative importance of particle reactive, weapons related contaminants originating from the nuclear facilities Mayak. Tomsk-7, and Semipalitinsk, which lie within the drainage basin. From our work to date, we draw the following conclusions: (1) Persistent non-fallout contamination is observed in the Ob River above its confluence with the Irtysh River, indicating contamination from the Tomsk-7 facility. (2) Non-fallout contamination in the Tobol River above its confluence with the Irtysh River indicates contamination from the Mayak facility. (3) Non-fallout contamination in the Irtysh River above its confluence with the Tobol River indicates contamination from the Semipalitinsk weapons test site. (4) The occurrence of isotopic ratios in Ob Delta sediments that are similar to those observed in source tributaries suggests that contamination from at least two sources has been transported along the length of the river system. (5) Global fallout, a result of high-yield atmospheric weapons tests conducted by the FSU and USA primarily, is the dominant source of Pu and Np to the region; however, there have been brief periods when inputs from non-fallout sources exceeded those from global fallout.

  19. Surpoids et obésité dans la population au-dessus de 20 ans en milieu urbain bamakois (Mali)

    PubMed Central

    Oumar Bâ, Hamidou; Menta, Ichaka; Camara, Youssouf; Sangaré, Ibrahima; Sidibé, Noumou; Doumbia, Seydou; Diarra, Mamadou Bocary

    2014-01-01

    Introduction Il est question dans notre travail d’étudier le SP et l'OB et les facteurs associés dans la population âgée de 20 ans ou plus. Méthodes Notre échantillon a été obtenu à partir d'une enquête sur les pathologies cardiovasculaires dans le District de Bamako et impliquant 2199 sujets de 5-104 ans, en sélectionnant tous les sujets âgés d'au moins 20 ans (1162). Pour chaque sujet, l'IMC, rapport taille / hanche et le tour de taille ont été déterminées. Les données ont été analysées avec SPSS 12. Résultats L’âge moyen était de 36,86 années, 61,4% étaient des femmes, 49,7% dans le secteur informel et 38,0% avaient réalisé l'enseignement primaire. Facteurs de risque cardiovasculaires étaient l'inactivité physique (72,4%), le tabagisme (12,2%) et hypertension (26,7%). La prévalence de l'obésité était de 8,8 et 14,7% respectivement sur la base de l'indice de masse et le tour de taille. Conclusion Le SP et l'OB sont à prendre en compte dans les mesures de politique sanitaire que dans la pratique quotidienne des professionnels de santé, il est peut-être plus utile d'utiliser plusieurs paramètres pour être à même de bien stratifier nos patients par rapport à leur risque. PMID:25932065

  20. A High Angular Resolution Survey of Massive Stars in Cygnus OB2: Results from the Hubble Space Telescope Fine Guidance Sensors

    DTIC Science & Technology

    2014-02-01

    observational period gap (Sana et al. 2008). The Orion Nebula cluster provides the closest example (d = 0.41 kpc; Menten et al. 2007) of an environment with a...et al. (2004) used the FGS instrument to search for binaries among 23 massive stars in the Carina Nebula region (d ≈ 2.5 kpc), and they discovered five...22% to 26% is consistent with the results from Nelan et al. (2004), who resolved 5 out of 23 OB stars (22%) in the Carina Nebula cluster. We were able

  1. Dusty OB Stars in the Small Magellanic Cloud. II. Extragalactic Disks or Examples of the Pleiades Phenomenon?

    NASA Astrophysics Data System (ADS)

    Adams, Joshua J.; Simon, Joshua D.; Bolatto, Alberto D.; Sloan, G. C.; Sandstrom, Karin M.; Schmiedeke, Anika; van Loon, Jacco Th.; Oliveira, Joana M.; Keller, Luke D.

    2013-07-01

    We use mid-infrared Spitzer spectroscopy and far-infrared Herschel photometry for a sample of 20 main sequence O9-B2 stars in the Small Magellanic Cloud (SMC) with strong 24 μm excesses to investigate the origin of the mid-IR emission. Either debris disks around the stars or illuminated patches of dense interstellar medium (ISM) can cause such mid-IR emission. In a companion paper, Paper I, we use optical spectroscopy to show that it is unlikely for any of these sources to be classical Be stars or Herbig Ae/Be stars. We focus our analysis on debris disks and cirrus hot spots. The local, prototype objects for these models are the debris disk around Vega and the heated dust cloud surrounding the stars in the Pleiades, also known as a cirrus hot spot. These two cases predict different dust masses, radii, origins, and structures, but the cleanest classification tools are lost by the poor physical resolution at the distance of the SMC. We also consider transition disks, which would have observable properties similar to debris disks. We begin classification by measuring angular extent in the highest resolution mid-IR images available. We find 3 out of 20 stars to be significantly extended, establishing them as cirrus hot spots. We then fit the IR spectral energy distributions to determine dust temperatures and masses. Analysis yields minimum grain sizes, thermal equilibrium distances, and the resultant dust mass estimates. We find the dust masses in the SMC stars to be larger than for any known debris disks. The difference in inferred properties is driven by the SMC stars being hotter and more luminous than known debris disk hosts and not in any directly observed dust properties, so this evidence against the debris disk hypothesis is circumstantial. Finally, we created a local comparison sample of bright mid-IR OB stars in the Milky Way (MW) by cross-matching the Wide-field Infrared Survey Explorer (WISE) and Hipparcos catalogs. We find that of the thousands of nearby

  2. DUSTY OB STARS IN THE SMALL MAGELLANIC CLOUD. II. EXTRAGALACTIC DISKS OR EXAMPLES OF THE PLEIADES PHENOMENON?

    SciTech Connect

    Adams, Joshua J.; Simon, Joshua D.; Bolatto, Alberto D.; Sloan, G. C.; Sandstrom, Karin M.; Schmiedeke, Anika; Van Loon, Jacco Th.; Oliveira, Joana M.; Keller, Luke D.

    2013-07-10

    We use mid-infrared Spitzer spectroscopy and far-infrared Herschel photometry for a sample of 20 main sequence O9-B2 stars in the Small Magellanic Cloud (SMC) with strong 24 {mu}m excesses to investigate the origin of the mid-IR emission. Either debris disks around the stars or illuminated patches of dense interstellar medium (ISM) can cause such mid-IR emission. In a companion paper, Paper I, we use optical spectroscopy to show that it is unlikely for any of these sources to be classical Be stars or Herbig Ae/Be stars. We focus our analysis on debris disks and cirrus hot spots. The local, prototype objects for these models are the debris disk around Vega and the heated dust cloud surrounding the stars in the Pleiades, also known as a cirrus hot spot. These two cases predict different dust masses, radii, origins, and structures, but the cleanest classification tools are lost by the poor physical resolution at the distance of the SMC. We also consider transition disks, which would have observable properties similar to debris disks. We begin classification by measuring angular extent in the highest resolution mid-IR images available. We find 3 out of 20 stars to be significantly extended, establishing them as cirrus hot spots. We then fit the IR spectral energy distributions to determine dust temperatures and masses. Analysis yields minimum grain sizes, thermal equilibrium distances, and the resultant dust mass estimates. We find the dust masses in the SMC stars to be larger than for any known debris disks. The difference in inferred properties is driven by the SMC stars being hotter and more luminous than known debris disk hosts and not in any directly observed dust properties, so this evidence against the debris disk hypothesis is circumstantial. Finally, we created a local comparison sample of bright mid-IR OB stars in the Milky Way (MW) by cross-matching the Wide-field Infrared Survey Explorer (WISE) and Hipparcos catalogs. We find that of the thousands of nearby

  3. The Contribution of Field OB Stars to the Ionization of the Diffuse Ionized Gas in M33

    NASA Astrophysics Data System (ADS)

    Hoopes, Charles G.; Walterbos, René A. M.

    2000-10-01

    We present a study of the ionizing stars associated with the diffuse ionized gas (DIG) and H II regions in the nearby spiral galaxy M33. We compare our Schmidt Hα image to the far-ultraviolet (FUV, 1520 Å) image from the Ultraviolet Imaging Telescope (UIT). The Hα/FUV ratio is higher in H II regions than in the DIG, suggesting an older population of ionizing stars in the DIG. Assuming ionization equilibrium, we convert the Hα flux to the number of Lyman continuum photons NLyc. When compared to models of evolving stellar populations, the NLyc/FUV ratio in H II regions is consistent with a young burst, while the DIG ratio resembles an older burst population, or a steady state population built up by constant star formation, which is probably a more accurate description of the stellar population in the field. The UIT data is complemented with archival FUV and optical images of a small portion of the disk of M33 obtained with WFPC2 on board the Hubble Space Telescope (HST). These images overlap low- and mid-luminosity H II regions as well as DIG, so we can investigate the stellar population in these environments. Using the HST FUV and optical photometry, we assign spectral types to the stars observed in DIG and H II regions. The photometry indicates that ionizing stars are present in the DIG. We compare the predicted ionizing flux with the amount required to produce the observed Hα emission, and we find that field OB stars in the HST images can account for 40%+/-12% of the ionization of the DIG, while the stars in H II regions can provide 107%+/-26% of the Hα luminosity of the H II regions. Due to the limited coverage of the HST data, we cannot determine if stars outside the HST fields ionize some of the DIG located in the HST fields, nor can we determine if photons from stars inside the HST fields leak out of the area covered by the HST fields. We do not find any correlation between leakage of ionizing photons and Hα luminosity for the H II regions in our HST

  4. Enhancing the Quality of Service for Real Time Traffic over Optical Burst Switching (OBS) Networks with Ensuring the Fairness for Other Traffics

    PubMed Central

    Al-Shargabi, Mohammed A.; Ismail, Abdulsamad S.

    2016-01-01

    Optical burst switching (OBS) networks have been attracting much consideration as a promising approach to build the next generation optical Internet. A solution for enhancing the Quality of Service (QoS) for high priority real time traffic over OBS with the fairness among the traffic types is absent in current OBS’ QoS schemes. In this paper we present a novel Real Time Quality of Service with Fairness Ratio (RT-QoSFR) scheme that can adapt the burst assembly parameters according to the traffic QoS needs in order to enhance the real time traffic QoS requirements and to ensure the fairness for other traffic. The results show that RT-QoSFR scheme is able to fulfill the real time traffic requirements (end to end delay, and loss rate) ensuring the fairness for other traffics under various conditions such as the type of real time traffic and traffic load. RT-QoSFR can guarantee that the delay of the real time traffic packets does not exceed the maximum packets transfer delay value. Furthermore, it can reduce the real time traffic packets loss, at the same time guarantee the fairness for non real time traffic packets by determining the ratio of real time traffic inside the burst to be 50–60%, 30–40%, and 10–20% for high, normal, and low traffic loads respectively. PMID:27583557

  5. B field in OB stars (BOB): The outstandingly strong magnetic field in the evolved He-strong star CPD -62° 2124

    NASA Astrophysics Data System (ADS)

    Castro, N.; Fossati, L.; Hubrig, S.; Järvinen, S. P.; Przybilla, N.; Nieva, M.-F.; Ilyin, I.; Carroll, T. A.; Schöller, M.; Langer, N.; Schneider, F. R. N.; Simón-Díaz, S.; Morel, T.; Butler, K.; BOB Collaboration

    2017-01-01

    The origin and evolution of magnetism in OB stars is far from being well understood. With approximately 70 magnetic OB stars known, any new object with unusual characteristics may turn out to be a key piece of the puzzle. We report the detection of an exceptionally strong magnetic field in the He-strong B2IV star CPD -62° 2124. Spectropolarimetric FORS2 and HARPSpol observations were analysed by two independent teams and procedures, concluding on a strong longitudinal magnetic field of approximately 5.2 kG. The quantitative characterisation of the stellar atmosphere yields an effective temperature of 23 650 ± 250 K, a surface gravity of 3.95 ± 0.10 dex and a surface helium fraction of 0.35 ± 0.02 by number. The metal composition is in agreement with the cosmic abundance standard, except for Mg, Si and S, which are slightly non-solar. The strong and broad ( 300 km s-1) disc-like emission displayed by the Hα line suggests a centrifugal magnetosphere supported by the strong magnetic field. Our results imply that CPD -62° 2124 is an early B-type star hosting one of the strongest magnetic fields discovered to date, and one of the most evolved He-strong stars known, with a fractional main-sequence lifetime of approximately 0.6. Based on observations made with ESO telescopes at the La Silla and Paranal observatories under programme ID 191.D-0255(G,I).

  6. Effect of ZnO on the interfacial bonding between Na 2O-B 2O 3-SiO 2 vitrified bond and diamond

    NASA Astrophysics Data System (ADS)

    Wang, P. F.; Li, Zh. H.; Li, J.; Zhu, Y. M.

    2009-08-01

    Diamond composites were prepared by sintering diamond grains with low melting Na 2O-B 2O 3-SiO 2 vitrified bonds in air. The influence of ZnO on the wettability and flowing ability of Na 2O-B 2O 3-SiO 2 vitrified bonds was characterized by wetting angle, the interfacial bonding states between diamond grains and the vitrified bonds were observed by scanning electron microscope (SEM), and the micro-scale bonding mechanism in the interfaces was investigated by means of energy-dispersive spectrometer (EDS), Fourier transform infrared (FTIR) spectrometer and X-ray photoelectron spectroscopy (XPS). The experimental results showed that ZnO facilitated the dissociation of boron/silicon-oxygen polyhedra and the formation of larger amount of non-bridging oxygen in the glass network, which resulted in the increase of the vitrified bonds' wettability and the formation of -C dbnd O, -O-H and -C-H bonds on the surface of diamond grains. B and Si diffused from the vitrified bonds to the interface, and C-C, C-O, C dbnd O and C-B bond formed on the surface of sintered diamond grains during sintering process, by which the interfacial bonding between diamond grains and the vitrified bonds was strengthened.

  7. ModObs: Atmospheric modelling for wind energy, climate and environment applications : exploring added value from new observation technique

    NASA Astrophysics Data System (ADS)

    Sempreviva, A. M.

    2009-04-01

    The EC FP6 Marie Curie Training Network "ModObs" http://www.modobs.windeng.net addresses the improvement of atmospheric boundary layer (ABL) models to investigate the interplay of processes at different temporal and spatial scales, and to explore the added value from new observation techniques. The overall goal is to bring young scientists to work together with experienced researchers in developing a better interaction amongst scientific communities of modelers and experimentalists, using a comprehensive approach to "Climate Change", "Clean Energy assessment" and "Environmental Policies", issues. This poster describes the work in progress of ten students, funded by the network, under the supervision of a team of scientists within atmospheric physics, engineering and satellite remote sensing and end-users such as companies in the private sector, all with the appropriate expertise to integrate the most advanced research methods and techniques in the following topics. MODELING: GLOBAL-TO-MESO SCALE: Analytical and process oriented numerical models will be used to study the interaction between the atmosphere and the ocean on a regional scale. Initial results indicate an interaction between the intensity of polar lows and the subsurface warm core often present in the Nordic Seas (11). The presence of waves, mainly swell, influence the MABL fluxes and turbulence structure. The regional and global wave effect on the atmosphere will be also studied and quantified (7) MESO-SCALE: Applicability of the planetary boundary layer (PBL) parametrizations in the meso-scale WRF model to marine atmospheric boundary layer (MABL) over the North Sea is investigated. The most suitable existing PBL parametrization will be additionally improved and used for downscaling North Sea past and future climates (2). Application of the meso-scale model (MM5 and WRF) for the wind energy in off-shore and coastal area. Set-up of the meso-scale model, post-processing and verification of the data from

  8. Analysis of High-Resolution OBS/H and MCS Data Across the Termination of a BSR in Lima Basin, Peru Margin - Velocity Structure and Paleo-BSRs

    NASA Astrophysics Data System (ADS)

    Garcia, P. G.; Pecher, I. A.; Kukowski, N.; Huebscher, C.; Clift, P. D.; Ruppel, C. D.; Bialas, J.

    2007-12-01

    Bottom simulating reflections (BSRs) in Lima Basin are confined to areas where the sub-surface structure is predicted to focus fluid flow. Most BSRs seem to be caused by free gas at the base of gas hydrate stability (BGHS). An increase of fluid flow and hence, methane flux, across the BGHS is thought to "trigger" formation of BSRs once methane concentration exceeds its solubility in pore water. Enhanced methane flux should also lead to elevated gas hydrate concentration above the BGHS. A BSR in the north of the basin coincides with outcropping layers, which often enhance fluid flow. During the GEOPECO campaign of the R/V Sonne in 2000, we deployed nine ocean bottom seismometers/hydrophones (OBS/Hs) at 1.85-km spacing across the termination of this BSR for a high-resolution OBS/H and short-streamer multichannel seismic transect. In order to investigate whether high gas hydrate concentrations are present in the hydrate zone, we compared velocities above the BSR to those in the same hydrate-free layer further landward (sequence L5 in an earlier classification). The OBS/H records were repositioned to sealevel in the τ-p domain followed by semblance analysis for determination of P-wave velocity (Vp). Vp in sequence L5 above the BSR appears lower than that at the hydrate-free site. This finding indicates that highly concentrated gas hydrates, if present at all, are confined to thin layers that do not significantly affect Vp of the entire interval. We have also identified at least two paleo-BSRs above the present BSR level. These paleo-BSRs most likely mark previous levels of the BGHS. Changes of the pressure/temperature regime must have happened sufficiently rapidly in order to "freeze" BSRs. We propose that the most likely mechanism for such rapid changes is sudden exhumation after mass wasting. The presence of at least two paleo-BSRs suggests that mass wasting has occurred repeatedly.

  9. Imaging of Lower-crustal Magma Chambers at an Ultraslow Spreading Ridge Segment using Elastic Waveform Inversion of a Sparse OBS Dataset

    NASA Astrophysics Data System (ADS)

    Jian, H.; Singh, S. C.; Chen, Y. J.; Li, J.

    2014-12-01

    The existence of axial magma chambers (AMC) is indicative of the magmatic crustal accretion at Mid-Ocean Ridges. They have been extensively imaged with seismic reflection data (e.g. multichannel seismic data), showing that the depth of the top reflector increases from 1 km to ~3 km below the seafloor, when the spreading rate decreases from fast to slow spreading. Under the ultraslow spreading environment, we have previously reported the discovery of a large lower-crustal low-velocity zone at the Southwest Indian Ridge at 50°28'E from 3-D travel time tomography of refraction data registered by an ocean bottom seismometer (OBS) array. These results suggest the presence of partial melt within the lower crust (>4 km bsf). Here we further improve the resolution of the AMC image by employing a 2-D time-domain elastic full waveform inversion (FWI) method. The FWI gives a higher resolution than travel time tomography as it utilizes amplitude information and does not require the high-frequency approximation used in travel time tomography. The non-linearity of the FWI is overcome by using the tomographic results as a starting model. We have selected a 70-km long profile running across the ridge axis around the segment center, where 340 shots spaced at ~220 m were recorded on 3 OBSs. The small number of OBS poses serious challenge for the success of the full waveform inversionFWI. In order to examine the resolvability of this sparse OBS dataset, we first performed FWI over a sparse synthetic data set. We find that the FWI of these this sparse dataset is capable of retrieving an isolated lower-crustal AMC anomaly beneath the ridge axis, although the resulting velocity anomaly is smeared out, particularly along the lateral direction. For the real-data inversion, the starting model was built from the 3-D travel time tomography. The inverted results clearly show the sharp boundary of the top of the low velocity zone, suggesting that the low velocity zone indeed corresponds to

  10. THE BOLOCAM GALACTIC PLANE SURVEY. III. CHARACTERIZING PHYSICAL PROPERTIES OF MASSIVE STAR-FORMING REGIONS IN THE GEMINI OB1 MOLECULAR CLOUD

    SciTech Connect

    Dunham, Miranda K.; Evans, Neal J.; Harvey, Paul; Merello, Manuel; Rosolowsky, Erik; Cyganowski, Claudia J.; Aguirre, James; Bally, John; Battersby, Cara; Ginsburg, Adam; Glenn, Jason; Stringfellow, Guy S.; Bradley, Eric Todd; Dowell, Darren; Drosback, Meredith; Schlingman, Wayne; Shirley, Yancy L.; Walawender, Josh; Williams, Jonathan P.

    2010-07-10

    We present the 1.1 mm Bolocam Galactic Plane Survey (BGPS) observations of the Gemini OB1 molecular cloud complex, and targeted NH{sub 3} observations of the BGPS sources. When paired with molecular spectroscopy of a dense gas tracer, millimeter observations yield physical properties such as masses, radii, mean densities, kinetic temperatures, and line widths. We detect 34 distinct BGPS sources above 5{sigma} = 0.37 Jy beam{sup -1} with corresponding 5{sigma} detections in the NH{sub 3}(1,1) transition. Eight of the objects show water maser emission (20%). We find a mean millimeter source FWHM of 1.12 pc and a mean gas kinetic temperature of 20 K for the sample of 34 BGPS sources with detections in the NH{sub 3}(1,1) line. The observed NH{sub 3} line widths are dominated by non-thermal motions, typically found to be a few times the thermal sound speed expected for the derived kinetic temperature. We calculate the mass for each source from the millimeter flux assuming the sources are isothermal and find a mean isothermal mass within a 120'' aperture of 230 {+-} 180 M{sub sun}. We find a total mass of 8400 M{sub sun} for all BGPS sources in the Gemini OB1 molecular cloud, representing 6.5% of the cloud mass. By comparing the millimeter isothermal mass to the virial mass calculated from the NH{sub 3} line widths within a radius equal to the millimeter source size, we find a mean virial parameter (M{sub vir}/M {sub iso}) of 1.0 {+-} 0.9 for the sample. We find mean values for the distributions of column densities of 1.0 x 10{sup 22} cm{sup -2} for H{sub 2}, and 3.0 x 10{sup 14} cm{sup -2} for NH{sub 3}, giving a mean NH{sub 3} abundance of 3.0 x 10{sup -8} relative to H{sub 2}. We find volume-averaged densities on the order of 10{sup 3}-10{sup 4} cm{sup -3}. The sizes and densities suggest that in the Gem OB1 region the BGPS is detecting the clumps from which stellar clusters form, rather than smaller, higher density cores where single stars or small multiple systems

  11. Thermodynamic properties of Ag2O--B2O3 glasses by a modified scale-transformed energy space sampling Monte Carlo method.

    PubMed

    Nakamura, Hideaki; Aniya, Masaru

    2006-03-01

    The density of states of Ag(2)O--B(2)O(3) glasses has been calculated by using a modified scale-transformed energy space sampling algorithm. This algorithm combines the scale-transformed energy space sampling algorithm and the Wang-Landau method. It is shown how the two algorithms can be combined to improve the efficiency of calculation. The thermodynamic properties, in particular the specific heat C(V), of the above-mentioned glass system is studied. At temperatures above 80 K, the value of specific heat C(v) is close to 22 J/mol/K. At low temperatures, the deviations of C(v) from a T(3) behavior are discernible, that is, C(v)/T(3) exhibits a hump at T = 7 K, which is in good agreement with the reported experimental behavior.

  12. Spectroscopic properties of Bi2ZnOB2O6 single crystals doped with Pr3+ ions: Absorption and luminescence investigations

    NASA Astrophysics Data System (ADS)

    Kasprowicz, D.; Brik, M. G.; Jaroszewski, K.; Pedzinski, T.; Bursa, B.; Głuchowski, P.; Majchrowski, A.; Michalski, E.

    2015-09-01

    Nonlinear optical Bi2ZnOB2O6 single crystals doped with Pr3+ ions were grown using the Kyropoulos method. The absorption and luminescence properties of these new systems were investigated for the first time. The crystals are characterized by the large values of nonlinear optical coefficients. Effective luminescence of the Pr3+ ions makes this system an excellent candidate for the near-infrared (NIR) and/or ultraviolet (UV) to visible (VIS) laser converters. Based on the obtained experimental spectroscopic data, detailed analysis of the absorption and luminescence spectra was performed using the conventional Judd-Ofelt theory. Those transitions, which can be potentially used for laser applications of the Pr3+ ion, have been identified. In addition to the intensity parameters Ω2, Ω4, Ω6 the branching ratios and radiative lifetimes were estimated for all possible transitions in the studied spectral region.

  13. Studies of hot B subdwarfs. Part 2: Energy distributions of three bright sdB/sdOB stars in the 950-5500 angstrom range

    NASA Technical Reports Server (NTRS)

    Wesemael, F.; Holberg, J. B.; Veilleux, S.; Lamontagne, R.; Fontaine, G.

    1985-01-01

    Voyager ultraviolet spectrometer observations of the subdwarf B or OB stars HD 205805, UV 1758+36 and Feige 66 are presented. All three objects display the H I Layman series in absorption. These observations are combined with low dispersion IUE spectrophotometry and with Stroemgren photometry to construct virtually complete energy distributions, which extend over the range 950-5500 angstroms. Effective temperatures based on model atmosphere calculations for high gravity, hydrogen rich stars are determined. Our analyses yield T Sub e 28,200 + or - 1300 K for HD 205805, T sub e 31, 800 + or - 1100 K for UV 1758+36, and T sub e 35,700 + or - 1500 K for Feige 66. The importance of far ultraviolet observations below L sub alpha in reducing the uncertainties associated with the interstellar extinction and the degradation of the IUE sensitivity is emphasized.

  14. Studies of hot B subdwarfs. II - Energy distributions of three bright sdB/sdOB stars in the 950-5500 A range

    NASA Technical Reports Server (NTRS)

    Wesemael, F.; Veilleux, S.; Lamontagne, R.; Fontaine, G.; Holberg, J. B.

    1985-01-01

    Voyager ultraviolet spectrometer observations of the subdwarf B or OB stars HD 205805, UV 1758+36 and Feige 66 are presented. All three objects display the H I Layman series in absorption. These observations are combined with low dispersion IUE spectrophotometry and with Stromgren photometry to construct virtually complete energy distributions, which extend over the range 950-5500 angstroms. Effective temperatures based on model atmosphere calculations for high gravity, hygrogen rich stars are determined. Our analyses yield T sub e 28,200 + or - 1300 K for HD 205805, T sub e 31, 800 + or - 1100 K for UV 1758+36, and T sub e 35,700 + or 1500 K for Feige 66. The importance of far ultraviolet observations below L sub alpha in reducing the uncertainties associated with the interstellar extinction and the degradation of the IUE sensitivity is emphasized.

  15. Gels and gel-derived glasses in the Na2O-B2O3-SiO2 system. [containerless melting in space

    NASA Technical Reports Server (NTRS)

    Mukherjee, S. P.

    1982-01-01

    The containerless melting of high-purity multicomponent homogeneous gels and gel-monoliths offers a unique approach to making ultrapure multicomponent optical glasses in the reduced gravity environment of space. Procedures for preparing and characterizing gels and gel-derived glasses in the Na2O-B2O3-SiO2 system are described. Preparation is based on the polymerization reactions of alkoxysilane with trimethyl borate or boric acid and a suitable sodium compound. The chemistry of the gelling process is discussed in terms of process parameters and the gel compositions. The physicochemical nature of gels prepared by three different procedures were found to be significantly different. IR absorption spectra indicate finite differences in the molecular structures of the different gels. The melting of the gel powders and the transformation of porous gel-monoliths to transparent 'glass' without melting are described.

  16. Gels and gel-derived glasses in the system Na2O-B2O3-SiO2

    NASA Technical Reports Server (NTRS)

    Mukherjee, S. P.

    1983-01-01

    The containerless melting of high-purity multicomponent homogeneous gels and gel monoliths offers a unique approach to making ultrapure multicomponent optical glasses in the reduced gravity environment of space. Procedures for preparing and characterizing gels and gel-derived glasses in the system Na2O-B2O3-SiO2 are described. Preparation is based on the polymerization reactions of alkoxysilane with trimethyl borate or boric acid and a suitable sodium compound. The chemistry of the gelling process is discussed in terms of process parameters and the gel compositions. The physicochemical nature of gels prepared by three different procedures was found to be significantly different. Infrared absorption spectra indicate finite differences in the molecular structures of the different gels. The melting of the gel powders and the transformation of porous gel monoliths to transparent 'glass' without melting are described.

  17. Ground-based CCD observations of two OB associations in M 31 obtained through replicas of two wide field/planetary camera filters

    SciTech Connect

    Hunter, D.A.; Winkelman, S. Michigan Univ., Ann Arbor )

    1990-08-01

    Ground-based photometry of stars in the OB associations NGC 206 and A184 in M 31 is presented and discussed. The filters that were used are replicas of the F555W and F785LP filters that are with the WF/PC on the Hubble Space Telescope and which will be used frequently in the study of stellar populations with that instrument. These data were obtained in order to aid in the interpretation of the flight data of these fields and are presented here in order to lay a foundation for those observations. These observations serve as a basis for further explorations with the HST of the stellar luminosity function in different galactic environments. 39 refs.

  18. VizieR Online Data Catalog: Periods of 4-10 Myr old T Tauri members of Orion OB1 (Karim+, 2016)

    NASA Astrophysics Data System (ADS)

    Karim, M. T.; Stassun, K. G.; Briceno, C.; Vivas, A. K.; Raetz, S.; Mateu, C.; Downes, J. J.; Calvet, N.; Hernandez, J.; Neuhauser, R.; Mugrauer, M.; Takahashi, H.; Tachihara, K.; Chini, R.; Cruz-Dias, G. A.; Aarnio, A.; James, D. J.; Hackstein, M.

    2017-02-01

    The Astronomia Variability Survey of Orion (CVSO) was carried out at the Llano del Hato National Astronomical Observatory in Venezuela, with the QUEST CCD mosaic camera (8000*8000pixels) on the 1m (clear aperture) Schmidt telescope, with a plate scale of 1.02''/pixel and field of view of 5.4 deg2. This V-, RC-, and IC-band multi-epoch survey, covering ~180deg2 of the Orion OB1 association, spans a time baseline of 12yr, from 1998 December to 2011 February. The 25 Ori cluster was observed by the 0.6/0.9m Schmidt-type telescope at Jena Observatory (Germany), the two 5.9'' telescopes at Observatorio Cerro Armazones (OCA, Chile), and the 1.5m reflector at the Gunma Astronomical Observatory in Japan, over four observing campaigns during the years 2010-2013. The Jena Schmidt-type telescope was equipped with the optical Schmidt Telescope Camera (STK), with an e2v 42-10 2048*2048 detector, yielding a plate scale of 1.55''/pixel and a field of view of 53'*53', thus encompassing most of the cluster. The Jena 50s exposures, all taken through the R filter, were centered on 25 Ori. A total of 8506 individual exposures were obtained in 108 nights. The Gunma 1.5m reflector observations were carried out by obtaining 60s integrations in R with the Gunma Low-resolution Spectrograph and Imager (GLOWS), which has an e2v CCD55-30 1250*1152 pixel detector with a 0.6''/pixel scale, covering a field of view of 12.5'*11.5'. Observations were obtained during four nights in year 2010. The Observatorio Cerro Armazones observations were done in the R band using the RoBoTT (Robotic Bochum TWin Telescope), which consists of twin Takahashi 150mm aperture apochromatic astrographs, each equipped with an Apogee U16M camera with a KAF-16803 4096*4096 pixel CCD, providing a 2.7°*2.7° field of view with 2.37''/pixel scale. The 60s exposures were centered on 25 Ori, spanning an area much larger than the cluster. OCA data were obtained during all YETI seasons. During the nights of 2006 January 8-15, we

  19. The 2010 Haiti earthquake sequence: new insight of the tectonic pattern from aftershocks and marine geophysical data : Haiti-OBS cruise

    NASA Astrophysics Data System (ADS)

    Mercier de Lepinay, B. F.; Mazabraud, Y.; Klingelhoefer, F.; Clouard, V.; Hello, Y.; Graindorge, D.; Marcaillou, B.; Crozon, J.; Saurel, J.; Charvis, P.; Mildor, B. S.; Deschamps, A.; Bouin, M.; Perrot, J.

    2010-12-01

    The devastating 2010 Haiti earthquake ruptured only a relatively short segment (~50km) of the Enriquillo-Plantain Garden fault (EPGF) a 600km long strike-slip fault running onland and offshore from Jamaica to Dominican Republic, with apparently no major surface rupture in the epicentral area. Considering the general behavior of such strike-slip fault (i.e. North Anatolian fault, San Andreas fault), we can expect that, following the 2010 earthquake, other large earthquakes will occur in the near future on adjacent segments. To contribute to the multinational scientific effort for a better understanding of the rupture process and the stress relaxation of this earthquake, we organized the Haiti-OBS cruise of the R/V L'Atalante few weeks after the catastrophe (Feb.5 to Feb.15, 2010, from and to Pointe-a-Pitre, Guadeloupe). Our goal was 1) to deploy a temporary network of seismologic stations -21 OBS, Ocean Bottom Seismometer, and 4 onland stations- and 2) to survey the detailed sea-floor features in relation with the deformation pattern of the area (multibeam bathymetry and mud-penetrator). We show that the distribution pattern of the aftershocks as well as the compressive surface structures observed in the geology and onshore/offshore morphology of the area are consistent with a deformation model implying a major left-lateral component along the EPGF, and a strong reverse component. The January 12, 2010 mainshock has been shown as very complex. However, in the first order, the mainshock and the distribution of the aftershocks, better localized by our temporary network, can be explained by the interaction between the strike-slip EPGF system and a blind folds-and-thrusts system. Thus, the general geological setting shows a southern extension until the southern part of the Canal du Sud area of the well-known fold and thrust system of the Hispaniola main block.

  20. Zodiacal Exoplanets in Time (ZEIT). III. A Short-period Planet Orbiting a Pre-main-sequence Star in the Upper Scorpius OB Association

    NASA Astrophysics Data System (ADS)

    Mann, Andrew W.; Newton, Elisabeth R.; Rizzuto, Aaron C.; Irwin, Jonathan; Feiden, Gregory A.; Gaidos, Eric; Mace, Gregory N.; Kraus, Adam L.; James, David J.; Ansdell, Megan; Charbonneau, David; Covey, Kevin R.; Ireland, Michael J.; Jaffe, Daniel T.; Johnson, Marshall C.; Kidder, Benjamin; Vanderburg, Andrew

    2016-09-01

    We confirm and characterize a close-in ({P}{{orb}} = 5.425 days), super-Neptune sized ({5.04}-0.37+0.34 {R}\\oplus ) planet transiting K2-33 (2MASS J16101473-1919095), a late-type (M3) pre-main-sequence (11 Myr old) star in the Upper Scorpius subgroup of the Scorpius-Centaurus OB association. The host star has the kinematics of a member of the Upper Scorpius OB association, and its spectrum contains lithium absorption, an unambiguous sign of youth (\\lt 20 Myr) in late-type dwarfs. We combine photometry from K2 and the ground-based MEarth project to refine the planet’s properties and constrain the host star’s density. We determine K2-33’s bolometric flux and effective temperature from moderate-resolution spectra. By utilizing isochrones that include the effects of magnetic fields, we derive a precise radius (6%-7%) and mass (16%) for the host star, and a stellar age consistent with the established value for Upper Scorpius. Follow-up high-resolution imaging and Doppler spectroscopy confirm that the transiting object is not a stellar companion or a background eclipsing binary blended with the target. The shape of the transit, the constancy of the transit depth and periodicity over 1.5 yr, and the independence with wavelength rule out stellar variability or a dust cloud or debris disk partially occulting the star as the source of the signal; we conclude that it must instead be planetary in origin. The existence of K2-33b suggests that close-in planets can form in situ or migrate within ˜10 Myr, e.g., via interactions with a disk, and that long-timescale dynamical migration such as by Lidov-Kozai or planet-planet scattering is not responsible for all short-period planets.

  1. A Deep X-ray look at a very massive star: HETGS spectroscopy of the blue hypergiant Cyg OB2-12 (HIP 101364)

    NASA Astrophysics Data System (ADS)

    Huenemoerder, David; Oskinova, Lidia; Ignace, Richard; Hamann, Wolf-Rainer; Schulz, Norbert S.; neilson, hilding; Shenar, Tomer

    2016-04-01

    We have obtained a Chandra/HETGS spectrum of one of the most massive and luminous stars in the Galaxy: the blue hypergiant Cyg OB2-12 (HIP 101364, spectral type B3 Ia+). This is the first measurement at high resolution of X-ray spectral lines in a blue hypergiant and allows comparison of X-ray properties between massive stars at different but related evolutionary stages: O-type supergiants, luminous blue variables, Wolf-Rayet stars, and blue hypergiants stars. The new data provide a look at how the most massive stars shed mass during their pre-supernova evolution. We find that In Cyg OB2-12 the resolved Si and Mg lines are broadened by about 1000 km/s (FWHM). The lines, however, do not show appreciable centroid shifts (<100 km/s), which would be much larger for canonical moderately thick winds (~500 km/s). The He-like Mg XI lines show evidence of photo-excitation, implying a wind origin close to the UV-bright photosphere. The spectrum also indicates relatively high temperature plasma, up to 22 MK (1.9 keV), showing significant continuum and emission lines below 5A (above 2.5 keV). Hence, at first glance, the spectrum resembles neither an O-star thick wind, nor a magnetically confined (narrow-line) plasma. We will present more detailed wind models using both X-ray and UV spectra to constrain fundamental physical parameters of this star.

  2. Structure of the Juan de Fuca Plate and Washington Forearc from 2D Travel Time Tomography of OBS and Land Seismometer Data along and East-West Transect

    NASA Astrophysics Data System (ADS)

    Carton, H. D.; Canales, J.; Janiszewski, H. A.; Carbotte, S. M.; Abers, G. A.; Trehu, A. M.; Nedimovic, M. R.

    2013-12-01

    In the summer of 2012 an offshore-onshore active source experiment was conducted spanning the Juan de Fuca plate and transecting the Cascadia margin at two locations. Two plate-scale transects offshore Oregon and Washington were designed to characterize the structure and evolution of the oceanic crust and uppermost mantle as the plate ages from formation at the Juan de Fuca Ridge to subduction at the Cascadia trench. They will provide evidence on how and where incorporation of water is taking place, and, further into the subduction zone, they will provide information on forearc structure and the subducting crust as it begins to dewater beneath the megathrust. Along the northern transect, airgun shots from R/V Lanseth's 6600 cu in array were fired at an interval of 500 m from the Endeavour segment on the Juan de Fuca Ridge to the 1000 m water depth contour on the wide accretionary wedge off Grays Harbor. These shots were recorded on 22 Ocean Bottom Seismometers (OBS) at ~15 km spacing along track and 15 land stations deployed in an ~140 km long east-west corridor in Washington. Two other sets of shots, at 37.5 m interval on the oceanic plate, and at 50 m interval on the wedge and shelf ~14-78 km from shore (thus extending shooting landward), were also recorded on the 15 land stations, and provide data that are easier to pick. Arrivals can be identified out of to a maximum of ~100 km on OBSs located on the oceanic plate and accretionary wedge, and a maximum of ~140 km on the land instruments. The two OBSs closest to shore (< 300 m water depth) returned noisy data and/or had issues. So far first arrivals (Psed, Pg and Pn) have been picked on the OBS gathers, which also show clear PmP phases. We will present two-dimensional P-wave travel time tomography results using the onshore-offshore wide-angle data from this northern transect.

  3. A Chrono-Chemo-Kinematic Survey of the Nearest OB Association: A Front-Row Seat to a Star-Formation Story 20 Million Years in the Making

    NASA Astrophysics Data System (ADS)

    Mamajek, Eric E.

    2015-08-01

    The Scorpius-Centaurus region is the nearest large-scale star-forming complex to the Sun, spanning the southern skies from the Southern Cross to the Oph/Sco region. The complex consists of three classic subgroups defined by Blaauw with mean ages spanning ~11-16 Myr (Upper Sco, Upper Cen-Lup, Lower Cen-Cru), some smaller <10 Myr-old peripheral associations (e.g. Eta Cha, Epsilon Cha, TW Hya groups, etc.), and on-going star-formation in several molecular clouds (e.g. Cha, Lup, CrA, Oph regions). I will show that the properties of the 3 main Sco-Cen subgroups shows that the common picture of monolithic, expanding, singular "bursts" of star-formation among OB subgroups is overly simplistic. I will discuss recent results regarding the membership of the Sco-Cen groups, the chemical composition of its solar-type members, evidence for additional substructures, and summarize what Sco-Cen appears to be revealing regarding the formation and evolution of GMC complexes and dissolution of young clusters.

  4. A Warm-up Laparoscopic Exercise Improves the Subsequent Laparoscopic Performance of Ob-Gyn Residents: a Low-Cost Laparoscopic Trainer

    PubMed Central

    Do, Ann T.; Kerr, Angela; Serur, Eli; Robertazzi, Robert R.; Stankovic, Miljan R.

    2006-01-01

    Introduction: Residents traditionally acquire surgical skills through on-the-job training. Minimally invasive laparoscopic techniques present additional demands to master complex surgical procedures in a remote 2-dimensional venue. We examined the effectiveness of a brief warm-up laparoscopic simulation toward improving operative proficiency. Methods: Using a “Poor-Man's Laparoscopy Simulator,” 12 Ob/Gyn residents and 12 medical students were allocated 10 minutes to transfer 30 tablets with a 5-mm grasper from point A to point B via laparoscopic visualization in a warm-up exercise. Participants repeated the exercise following a 5-minute pause. Mean scores, expressed in seconds/tablet, and overall improvement (percentage difference between warm-up and follow-up) were analyzed according to postgraduate standing (PGY1-4), dexterity skills, and pertinent vocational activities. Results: Significant improvements were noted for both residents (+25%) and medical students (+29%), P<0.0001. Scores between the 2 groups, however, were not significant (P=0.677). Proficiency was not influenced by PGY standing. Interestingly, the best (8.73 sec/pill) and the worst (25 sec/pill) scores were attained by a medical student and a chief resident, respectively, suggesting the contribution of individual aptitude. Conclusion: A brief warm-up exercise before an actual laparoscopic surgical procedure significantly improves subsequent laparoscopic performance. PMID:17212883

  5. The Rotation Period Distributions of 4-10 Myr T Tauri Stars in Orion OB1: New Constraints on Pre-main-sequence Angular Momentum Evolution

    NASA Astrophysics Data System (ADS)

    Karim, Md Tanveer; Stassun, Keivan G.; Briceño, César; Vivas, A. Katherina; Raetz, Stefanie; Mateu, Cecilia; José Downes, Juan; Calvet, Nuria; Hernández, Jesús; Neuhäuser, Ralph; Mugrauer, Markus; Takahashi, Hidenori; Tachihara, Kengo; Chini, Rolf; Cruz-Dias, Gustavo A.; Aarnio, Alicia; James, David J.; Hackstein, Moritz

    2016-12-01

    Most existing studies of the angular momentum evolution of young stellar populations have focused on the youngest (≲1-3 Myr) T Tauri stars. In contrast, the angular momentum distributions of older T Tauri stars (˜4-10 Myr) have been less studied, even though they hold key insights to understanding stellar angular momentum evolution at a time when protoplanetary disks have largely dissipated and when models therefore predict changes in the rotational evolution that can in principle be tested. We present a study of photometric variability among 1974 confirmed T Tauri members of various subregions of the Orion OB1 association, and with ages spanning 4-10 Myr, using optical time series from three different surveys. For 564 of the stars (˜32% of the weak-lined T Tauri stars and ˜13% of the classical T Tauri stars in our sample) we detect statistically significant periodic variations, which we attribute to the stellar rotation periods, making this one of the largest samples of T Tauri star rotation periods yet published. We observe a clear change in the overall rotation period distributions over the age range 4-10 Myr, with the progressively older subpopulations exhibiting systematically faster rotation. This result is consistent with angular momentum evolution model predictions of an important qualitative change in the stellar rotation periods starting at ˜5 Myr, an age range for which very few observational constraints were previously available.

  6. Transformation Kinetics of Chlorinated Ethenes by Methylosinus trichosporium OB3b and Detection of Unstable Epoxides by On-Line Gas Chromatography

    PubMed Central

    van Hylckama, Vlie... J.; de Koning, W.; Janssen, D. B.

    1996-01-01

    A rapid and accurate method for the determination of transformation kinetics of volatile organic substrates was developed. Concentrations were monitored by on-line gas chromatographic analysis of the headspace of well-mixed incubation mixtures. With this method, the kinetics of transformation of a number of C(inf1) and C(inf2) halogenated alkanes and alkenes by Methylosinus trichosporium OB3b expressing particulate methane monooxygenase or soluble methane monooxygenase (sMMO) were studied. Apparent specific first-order rate constants for cells expressing sMMO decreased in the order of dichloromethane, vinyl chloride, cis-1,2-dichloroethene, trans-1,2-dichloroethene, 1,1-dichloroethene, trichloroethene, chloroform, and 1,2-dichloroethane. During the degradation of trichloroethene, cis-1,2-dichloroethene, trans-1,2-dichloroethene, and vinyl chloride, the formation of the corresponding epoxides was observed. The epoxide of vinyl chloride and the epoxide of trichloroethene, which temporarily accumulated in the medium, were chemically degraded according to first-order kinetics, with half-lives of 78 and 21 s, respectively. Cells expressing sMMO actively degraded the epoxide of cis-1,2-dichloroethene but not the epoxide of trans-1,2-dichloroethene. Methane and acetylene inhibited degradation of the epoxide of cis-1,2-dichloroethene, indicating that sMMO was involved. PMID:16535402

  7. Effects of Ammonium and Non-Ammonium Salt Additions on Methane Oxidation by Methylosinus trichosporium OB3b and Maine Forest Soils.

    PubMed

    King, G M; Schnell, S

    1998-01-01

    Additions of ammonium and non-ammonium salts inhibit atmospheric methane consumption by soil at salt concentrations that do not significantly affect the soil water potential. The response of soils to non-ammonium salts has previously raised questions about the mechanism of ammonium inhibition. Results presented here show that inhibition of methane consumption by non-ammonium salts can be explained in part by ion-exchange reactions: cations desorb ammonium, with the level of desorption varying as a function of both the cation and anion added; differential desorption results in differential inhibition levels. Differences in the extent of inhibition among ammonium salts can also be explained in part by the effects of anions on ammonium exchange. In contrast, only minimal effects of cations and anions are observed in liquid cultures of Methylosinus trichosporium OB3b. The comparable level of inhibition by equinormal concentrations of NH(4)Cl and (NH(4))(2)SO(4) and the insensitivity of salt inhibition to increasing methane concentrations (from 10 to 100 ppm) are of particular interest, since both of these patterns are in contrast to results for soils. The greater inhibition of methane consumption for NH(4)Cl than (NH(4))(2)SO(4) in soils can be attributed to increased ammonium adsorption by sulfate; increasing inhibition by non-ammonium salts with increasing methane concentrations can be attributed to desorbed ammonium and a physiological mechanism proposed previously for pure cultures.

  8. NEAR-INFRARED PERIODIC AND OTHER VARIABLE FIELD STARS IN THE FIELD OF THE CYGNUS OB7 STAR-FORMING REGION

    SciTech Connect

    Wolk, Scott J.; Rice, Thomas S.; Aspin, Colin A.

    2013-04-15

    We present a subset of the results of a three-season, 124 night, near-infrared monitoring campaign of the dark clouds Lynds 1003 and Lynds 1004 in the Cygnus OB7 star-forming region. In this paper, we focus on the field star population. Using three seasons of UKIRT J, H, and K-band observations spanning 1.5 years, we obtained high-quality photometry on 9200 stars down to J = 17 mag, with photometric uncertainty better than 0.04 mag. After excluding known disk-bearing stars we identify 149 variables-1.6% of the sample. Of these, about 60 are strictly periodic, with periods predominantly <2 days. We conclude this group is dominated by eclipsing binaries. A few stars have long period signals of between 20 and 60 days. About 25 stars have weak modulated signals, but it was not clear if these were periodic. Some of the stars in this group may be diskless young stellar objects with relatively large variability due to cool starspots. The remaining {approx}60 stars showed variations which appear to be purely stochastic.

  9. Oxygen isotope and deuterium composition of snow cover on the profile of Western Siberia from Tomsk to the Gulf of Ob

    NASA Astrophysics Data System (ADS)

    Vasil'chuk, Yu. K.; Shevchenko, V. P.; Lisitzin, A. P.; Budantseva, N. A.; Vorobiov, S. N.; Kirpotin, S. N.; Krizkov, I. V.; Manasypov, R. M.; Pokrovsky, O. S.; Chizhova, Ju. N.

    2016-12-01

    The purpose of this work is to study the variability of the isotope composition (δ18O, δD, d exc) of the snow cover on a long transect of Western Siberia from the southern taiga to the tundra. The study of the snow cover is of paleogeographic, paleogeocryological, and paleohydrological value. The snow cover of western Siberia was sampled on a broadly NS transzonal profile from the environs of Tomsk (southern taiga zone) to the eastern coast of the Gulf of Ob (tundra zone) from February 19 to March 4, 2014. Snow samples were collected at 31 sites. Most of the samples represented by fresh snow, i.e., snow that had fallen a day before the moment of sampling were collected in two areas. In the area of Yamburg, the snow specimens collected from the surface are most probably settled snow of different ages. The values of δ18O in the snow from Tomsk to Yamburg varied from-21.89 to-32.82‰, and the values of δD, from-163.3 to-261.2‰. The value of deuterium excess was in the range of 4.06-19.53‰.

  10. Effects of Ammonium and Non-Ammonium Salt Additions on Methane Oxidation by Methylosinus trichosporium OB3b and Maine Forest Soils†

    PubMed Central

    King, G. M.; Schnell, S.

    1998-01-01

    Additions of ammonium and non-ammonium salts inhibit atmospheric methane consumption by soil at salt concentrations that do not significantly affect the soil water potential. The response of soils to non-ammonium salts has previously raised questions about the mechanism of ammonium inhibition. Results presented here show that inhibition of methane consumption by non-ammonium salts can be explained in part by ion-exchange reactions: cations desorb ammonium, with the level of desorption varying as a function of both the cation and anion added; differential desorption results in differential inhibition levels. Differences in the extent of inhibition among ammonium salts can also be explained in part by the effects of anions on ammonium exchange. In contrast, only minimal effects of cations and anions are observed in liquid cultures of Methylosinus trichosporium OB3b. The comparable level of inhibition by equinormal concentrations of NH4Cl and (NH4)2SO4 and the insensitivity of salt inhibition to increasing methane concentrations (from 10 to 100 ppm) are of particular interest, since both of these patterns are in contrast to results for soils. The greater inhibition of methane consumption for NH4Cl than (NH4)2SO4 in soils can be attributed to increased ammonium adsorption by sulfate; increasing inhibition by non-ammonium salts with increasing methane concentrations can be attributed to desorbed ammonium and a physiological mechanism proposed previously for pure cultures. PMID:16349485

  11. L'obésité en consultation cardiologique à Lomé: prévalence et facteurs de risque cardio-vasculaire associés - étude chez 1200 patients

    PubMed Central

    Pessinaba, Soulemane; Yayehd, Komlavi; Pio, Machiude; Baragou, Réné; Afassinou, Yaovi; Tchérou, Tchaa; Damorou, Findibé

    2012-01-01

    Introduction Introduction: Les objectifs de ce travail étaient de déterminer la fréquence de l'obésité et celle des autres facteurs de risque cardio-vasculaire chez ces patients obèses à Lomé (Togo). Méthodes Il s'est agi d'une étude multicentrique transversale de prévalence. Elle s'est déroulée du 05 septembre 2005 au 04 mars 2006 et a porté sur les malades vus en consultation externe dans 3 services de cardiologie de la commune de Lomé. Ont été inclus dans cette étude les malades ayant un surpoids selon les normes de l'OMS. Résultats Parmi 1200 patients vus en consultations, 779 (64,92%) avaient une surcharge pondérale. L’âge moyen était de 49,53 ± 17,24 ans. L'obésité était plus fréquente chez les femmes (79,49%) que chez les hommes (20,51%). Un antécédent d'obésité familiale (61,8%) était le principal facteur favorisant. Les autres facteurs de risque cardio-vasculaire retrouvés étaient: sédentarité (82% vs50% chez les non obèses), hypertension artérielle (54,8% vs 39,2%), alcool (50,9% vs 43,9%), dyslipidémie (34,5% vs 20%), diabète (30,9% vs 10,7%) et tabac (14,1% vs 20,3%). La différence était statistiquement significative entre les deux groupes. Les principales complications cardiovasculaires observées chez les obèses étaient: l'ischémie myocardique (26,7%), l'hypertrophie ventriculaire gauche (46,4%), la dilatation cavitaire cardiaque (30,1%) et les accidents vasculaires cérébraux (7,1%). Conclusion L'obésité est un problème de santé publique au Togo. Sa prévalence est très élevée et elle est le plus souvent associée aux autres facteurs de risque cardio-vasculaire. Des mesures préventives doivent être mises en jeu pour lutter contre ce facteur de risque. Mots clés: Obésité, prévalence, facteurs de risque. PMID:23133699

  12. Kharlamova, N. F. Climate Changes over the 20th and 21st Centuries in the Upper Basin of the Ob and Irtysh Rivers (Altai Region)

    NASA Astrophysics Data System (ADS)

    Fedorovna, K. N., II

    2015-12-01

    The Russian climate is more sensitive to global warming than the climate in many other parts of the world. According to the Second Climate Change National Assessment, since the mid-1970s, the average temperature has been rising with rate of 0.43 ° C / 10 years, which is more than two times higher than the rate of global warming. In the Altai region, the rate of temperature change is higher than the average for Russia with an annual surface air temperature increase equal to 1.8°C the 20th century. The maximum value of this increase the past 50 years (1963-2013) was found in the intermountain basins of Altai (+ 2.6°C) mainly due to the winter and spring warming with changes in the summer season being considerably smaller. This warming is accompanied with negative tendencies in annual precipitation over the entire Altai Krai. The mountain ranges of Altai are called the "water tower" of Northern Eurasia. The northward flow of numerous rivers streaming down from these ranges in the Basin of the Ob and the Irtysh Rivers is formed by melting of Altai glaciers and snowfields. Since the middle of the 19th century the largest glaciers in the Altai have retreated by 1.5-2 km and the thickness of their tails decreased by 50-70 m. The reduction of mountain glaciers poses a threat of depletion of water flow to major agricultural regions downstream affecting human activity and even the drinking water availability. Permafrost in the Altai Mountains is actively degraded (thawing), which represents a danger for infrastructure (first of all for roads and pipelines) and increases risk of catastrophic events (landslides, mudflows). Continued warming could contribute to a significant reduction of water resources, biodiversity and other negative processes in the region.The reported study was partially supported by the Russian Foundation for Baseline Research (project No. 15-45-04450).

  13. Marker Exchange Mutagenesis of mxaF, Encoding the Large Subunit of the Mxa Methanol Dehydrogenase, in Methylosinus trichosporium OB3b

    PubMed Central

    Farhan Ul Haque, Muhammad; Gu, Wenyu; DiSpirito, Alan A.

    2015-01-01

    Methanotrophs have remarkable redundancy in multiple steps of the central pathway of methane oxidation to carbon dioxide. For example, it has been known for over 30 years that two forms of methane monooxygenase, responsible for oxidizing methane to methanol, exist in methanotrophs, i.e., soluble methane monooxygenase (sMMO) and particulate methane monooxygenase (pMMO), and that expression of these two forms is controlled by the availability of copper. Specifically, sMMO expression occurs in the absence of copper, while pMMO expression increases with increasing copper concentrations. More recently, it was discovered that multiple forms of methanol dehydrogenase (MeDH), Mxa MeDH and Xox MeDH, also exist in methanotrophs and that the expression of these alternative forms is regulated by the availability of cerium. That is, expression of Xox MeDH increases in the presence of cerium, while Mxa MeDH expression decreases in the presence of cerium. As it had been earlier concluded that pMMO and Mxa MeDH form a supercomplex in which electrons from Mxa MeDH are back donated to pMMO to drive the initial oxidation of methane, we speculated that Mxa MeDH could be rendered inactive through marker-exchange mutagenesis but growth on methane could still be possible if cerium was added to increase the expression of Xox MeDH under sMMO-expressing conditions. Here we report that mxaF, encoding the large subunit of Mxa MeDH, could indeed be knocked out in Methylosinus trichosporium OB3b, yet growth on methane was still possible, so long as cerium was added. Interestingly, growth of this mutant occurred in both the presence and the absence of copper, suggesting that Xox MeDH can replace Mxa MeDH regardless of the form of MMO expressed. PMID:26712545

  14. Magnetic inhibition of convection and the fundamental properties of low-mass stars. III. A consistent 10 Myr age for the Upper Scorpius OB association

    NASA Astrophysics Data System (ADS)

    Feiden, Gregory A.

    2016-09-01

    When determining absolute ages of identifiably young stellar populations, results strongly depend on which stars are studied. Cooler (K, M) stars typically yield ages that are systematically younger than warmer (A, F, G) stars by a factor of two. I explore the possibility that these age discrepancies are the result of magnetic inhibition of convection in cool young stars by using magnetic stellar evolution isochrones to determine the median age of the Upper Scorpius subgroup of the Scorpius-Centaurus OB association. A median age of 10 Myr consistent across spectral types A through M is found, except for a subset of F-type stars that appear significantly older. Agreement is shown for ages derived from the Hertzsprung-Russell (HR) diagram and from the empirical mass-radius relationship defined by eclipsing multiple-star systems. Surface magnetic field strengths required to produce agreement are approximately 2.5 kG and are predicted from a priori estimates of thermal equipartition values. A region in the HR diagram is identified that plausibly connects stars whose structures are weakly influenced by the presence of magnetic fields with those whose structures are strongly influenced by magnetic fields. The models suggest that this region is characterized by stars with rapidly thinning outer convective envelopes where the radiative core mass is greater than 75% of the total stellar mass. Furthermore, depletion of lithium predicted from magnetic models appears in better agreement with observed lithium equivalent widths than predictions from non-magnetic models. These results suggest that magnetic inhibition of convection plays an important role in the early evolution of low-mass stars and that it may be responsible for noted age discrepancies in young stellar populations.

  15. The star formation history and accretion-disc fraction among the K-type members of the Scorpius-Centaurus OB association

    NASA Astrophysics Data System (ADS)

    Pecaut, Mark J.; Mamajek, Eric E.

    2016-09-01

    We present results of a spectroscopic survey for new K- and M-type members of Scorpius-Centaurus (Sco-Cen), the nearest OB Association (˜100-200 pc). Using an X-ray, proper motion and colour-magnitude selected sample, we obtained spectra for 361 stars, for which we report spectral classifications and Li and Hα equivalent widths. We identified 156 new members of Sco-Cen, and recovered 51 previously published members. We have combined these with previously known members to form a sample of 493 solar-mass (˜0.7-1.3 M⊙) members of Sco-Cen. We investigated the star formation history of this sample, and re-assessed the ages of the massive main-sequence turn-off and the G-type members in all three subgroups. We performed a census for circumstellar discs in our sample using WISE infrared data and find a protoplanetary disc fraction for K-type stars of 4.4^{+1.6}_{-0.9} per cent for Upper Centaurus-Lupus and Lower Centaurus-Crux at ˜16 Myr and 9.0^{+4.0}_{-2.2} per cent for Upper Scorpius at ˜10 Myr. These data are consistent with a protoplanetary disc e-folding time-scale of ˜4-5 Myr for ˜1 M⊙ stars, twice that previously quoted, but consistent with the Bell et al. revised age scale of young clusters. Finally, we construct an age map of Scorpius-Centaurus which clearly reveals substructure consisting of concentrations of younger and older stars. We find evidence for strong age gradients within all three subgroups. None of the subgroups are consistent with being simple, coeval populations which formed in single bursts, but likely represents a multitude of smaller star formation episodes of hundreds to tens of stars each.

  16. Stochastic forecasting of the geomagnetic field from the COV-OBS.x1 geomagnetic field model, and candidate models for IGRF-12

    NASA Astrophysics Data System (ADS)

    Gillet, Nicolas; Barrois, Olivier; Finlay, Christopher C.

    2015-05-01

    We present the geomagnetic field model COV-OBS.x1, covering 1840 to 2020, from which have been derived candidate models for the IGRF-12. Towards the most recent epochs, it is primarily constrained by first differences of observatory annual means and measurements from the Oersted, Champ, and Swarm satellite missions. Stochastic information derived from the temporal spectra of geomagnetic series is used to construct the a priori model covariance matrix that complements the constraint brought by the data. This approach makes it possible the use of a posteriori model errors, for instance, to measure the `observations' uncertainties in data assimilation schemes for the study of the outer core dynamics. We also present and illustrate a stochastic algorithm designed to forecast the geomagnetic field. The radial field at the outer core surface is advected by core motions governed by an auto-regressive process of order 1. This particular choice is motivated by the slope observed for the power spectral density of geomagnetic series. Accounting for time-correlated model errors (subgrid processes associated with the unresolved magnetic field) is made possible thanks to the use of an augmented state ensemble Kalman filter algorithm. We show that the envelope of forecasts includes the observed secular variation of the geomagnetic field over 5-year intervals, even in the case of rapid changes. In a purpose of testing hypotheses about the core dynamics, this prototype method could be implemented to build the `state zero' of the ability to forecast the geomagnetic field, by measuring what can be predicted when no deterministic physics is incorporated into the dynamical model.

  17. The Virtual Observatory Service TheoSSA: Establishing a Database of Synthetic Stellar Flux Standards II. NLTE Spectral Analysis of the OB-Type Subdwarf Feige 110

    NASA Technical Reports Server (NTRS)

    Rauch, T.; Rudkowski, A.; Kampka, D.; Werner, K.; Kruk, J. W.; Moehler, S.

    2014-01-01

    Context. In the framework of the Virtual Observatory (VO), the German Astrophysical VO (GAVO) developed the registered service TheoSSA (Theoretical Stellar Spectra Access). It provides easy access to stellar spectral energy distributions (SEDs) and is intended to ingest SEDs calculated by any model-atmosphere code, generally for all effective temperatures, surface gravities, and elemental compositions. We will establish a database of SEDs of flux standards that are easily accessible via TheoSSA's web interface. Aims. The OB-type subdwarf Feige 110 is a standard star for flux calibration. State-of-the-art non-local thermodynamic equilibrium stellar-atmosphere models that consider opacities of species up to trans-iron elements will be used to provide a reliable synthetic spectrum to compare with observations. Methods. In case of Feige 110, we demonstrate that the model reproduces not only its overall continuum shape from the far-ultraviolet (FUV) to the optical wavelength range but also the numerous metal lines exhibited in its FUV spectrum. Results. We present a state-of-the-art spectral analysis of Feige 110. We determined Teff =47 250 +/- 2000 K, log g=6.00 +/- 0.20, and the abundances of He, N, P, S, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, and Ge. Ti, V, Mn, Co, Zn, and Ge were identified for the first time in this star. Upper abundance limits were derived for C, O, Si, Ca, and Sc. Conclusions. The TheoSSA database of theoretical SEDs of stellar flux standards guarantees that the flux calibration of astronomical data and cross-calibration between different instruments can be based on models and SEDs calculated with state-of-the-art model atmosphere codes.

  18. Successful Nd3+ Doping of Li2O-B2O3-Al2O3 Vitreous System: Optical Characterization and Judd-Ofelt Spectroscopic Calculations

    NASA Astrophysics Data System (ADS)

    Silva, V. A.; Morais, P. C.; Morais, R. F.; Dantas, N. O.

    2016-12-01

    This study reports on the synthesis and the physical characterization of a ternary boron-rich (B-rich) lithium-boron-aluminum (LBA: Li2O-B2O3-Al2O3) vitreous system successfully doped with increasing Nd2O3 content ( xNd2O3:LBA) in the range 0 ≤ x ≤ 5 wt %. The as-produced samples were investigated using optical absorption, photoluminescence emission, Raman spectroscopy, and differential thermal analysis. The Judd-Ofelt (JO) theory was used to assess the intensity parameters ( Ω λ ), transition probabilities ( A( J, J')), branch ratios ( β), emission cross-sections ( σ), quantum efficiencies ( Y), experimental ( τ exp ) and calculated ( τ rad ) radiative lifetimes, and the spectroscopic quality values ( χ = Ω 4/ Ω 6) as a function of the nominal Nd2O3 doping content. Over the range of our investigation (0 ≤ x ≤ 5 wt %), we found that the Ω 2 and Ω 6JO parameters monotonically increased from 0.17 to 1.26 × 10-20 and from 1.19 to 1.84 × 10-20, respectively. In contrast, over the same range of nominal Nd2O3 doping content we found that the Ω 4 JO parameter decreased monotonically from 4.12 to 2.05 × 1 0-20. Although the τ exp values increased at the low end of nominal Nd2O3 content (up to 2.5 wt %), nonradiative energy transfer mechanisms (e.g., energy migration, cross-relaxation, and losses from networked phonons and O-H vibrational modes) governed the process at the high end of the nominal Nd2O3 content. A competition mechanism was proposed to explain the observed behavior in the 4F3/2 ⟶ 4IJ'transition lifetime for hosted Nd3+ ions.

  19. A DYNAMICAL STUDY OF SUSPECTED RUNAWAY STARS AS TRACES OF PAST SUPERNOVA EXPLOSIONS IN THE REGION OF THE SCORPIUS-CENTAURUS OB ASSOCIATION

    SciTech Connect

    Jilinski, E.; Ortega, V. G.; Drake, N. A.; De la Reza, R.

    2010-09-20

    We address the question of identifying possible past supernovae events taking place in the region of the Scorpius-Centaurus (Sco-Cen) OB association based on stars proposed by Hoogerwerf et al. With this purpose, we obtained a time series of high-resolution spectra of six stars (HIP 42038, HIP 46950, HIP 48943, HIP 69491, HIP 76013, and HIP 82868) which, according to Hoogerwerf et al., may have been runaway stars with origins in the region of the Sco-Cen association. This also includes the nearby young open clusters IC 2391 and IC 2602. If confirmed, such supernovae events could, in principle, have played a role in triggering the formation of some small stellar groups thought to be associated with the Sco-Cen association. Our analysis shows that, except for HIP 48943, the remaining stars are spectroscopic binary systems. For HIP 46950 and HIP 69491, this was already noted by other authors. Our high-resolution spectra allowed us to obtain the radial velocities for all the stars which, combined with their proper motions and parallaxes from Hipparcos, provide a means to investigate, by retracing their orbits, if the Sco-Cen region was, in fact, the origin of these stars. We find that none of these systems originated in the Sco-Cen region. Exploring the possibility that the birthplace of the studied stars occurred in the clusters IC 2391 and IC 2602, we noticed that at the epoch of 2-3 Myr ago these clusters were at a distance comparable with their tidal radii.

  20. Prévalence et facteurs de risque du surpoids et de l'obésité dans une population d'enfants scolarisés en milieu urbain à Sfax, Tunisie

    PubMed Central

    Regaieg, Sofien; Charfi, Nadia; Trabelsi, Lobna; Kamoun, Mahdi; Feki, Habib; Yaich, Sourour; Abid, Mohamed

    2014-01-01

    Introduction L'objectif de ce travail etait d’étudier la prévalence du surpoids et de l'obésité chez un groupe d'enfants d’âge scolaire, habitant la ville de Sfax en Tunisie, et identifier les facteurs favorisant la prise pondérale Méthodes Il s'agossait d'une enquête descriptive transversale était réalisée en 2011 sur un échantillon représentatif d’élèves recrutés dans 11 écoles primaires publiques. Des informations concernant les caractéristiques sociodémographiques, les habitudes alimentaires et le comportement sédentaire pour chaque élève ont été précisées au moyen d'un questionnaire Résultats Nous avons colligé 1529 élèves, âgés entre 9 et 12 ans et se répartissant en 787 garçons (51,14%) et 747 filles (48,86%). Selon les seuils de référence de l'IOTF, la fréquence de l'obésité était de 2,4% et celle du surpoids était de 6,3%. L'obésité était significativement associée à l'obésité parentale, un niveau socioéconomique élevé, la prise de plus de deux goûters par jour et à l'activité sédentaire. Conclusion L'identification des facteurs de risque du surpoids et de l'obésité infantile permettrait de dépister les enfants à risques afin de leur proposer des mesures de prévention adaptées. Ces mesures de prévention devraient inclure non seulement des approches individuelles, mais aussi l'environnement social et physique de l'enfant. PMID:25018807

  1. Find an Ob-Gyn

    MedlinePlus

    Advertisement Member Login Join Pay Dues Follow us: Women's Health Care Physicians Contact Us My ACOG ACOG ... Page Contact: District & Section Activities DistrictOffice@acog.org Advertisement Resources & Publications Committee Opinions Practice Bulletins Patient Education ...

  2. Importance of large-scale bathymetry features on 2011 Tohoku tsunami waveforms through comparison of simulations with the spatially dense ALBACORE OBS array data

    NASA Astrophysics Data System (ADS)

    Kohler, M. D.; Lynett, P. J.; Legg, M. R.; Weeraratne, D. S.

    2012-12-01

    In March 2011, a deployment of ocean bottom seismometers (OBSs) off the coast of Southern California recorded the tsunami resulting from the Mw=9.0 Tohoku, Japan earthquake with very high spatial resolution. The ALBACORE (Asthenosphere and Lithosphere Broadband Architecture from the California Offshore Region Experiment) OBS array spanned a region that was 150 km north-south by 400 km east-west, extending into deep open ocean west of the Patton escarpment. In that array, 22 stations with a spacing of 75 km had differential pressure gauges (DPGs) that recorded water pressure waveform data continuously at 50 samples/second. The DPG tsunami records across the entire array show multiple large-amplitude, coherent phases arriving one hour to more than 36 hours after the initial tsunami phase. To determine the source of the large-amplitude coherent phases, gravity ocean wave propagation calculations were carried out for the Pacific Ocean. Simulated pressure waveforms were compared with data for the ALBACORE stations, as well as for the NOAA DART buoys. The linear, non-dispersive shallow-water simulations include bottom frictional effects, and use the USGS NEIC Tohoku slip model and ETOPO2 (two-minute spatial resolution) bathymetry. The predicted travel times of the initial arrivals are found to be less than 1% different from the observed travel times in the southern California ALBACORE DPG data. In order to gauge the effects of large-scale features in Pacific Ocean bathymetry, several large-scale features were individually removed, and simulations were carried out for the modified bathymetry. The removed features include the Emperor Seamount chain, Hawaiian Islands, Oceania, French Polynesia, and the South American coastline. The results show that the removal of these features has an effect on the arrival time of the phases that depends on the feature proximity to the direct path, but their removal does not have a significant effect on the frequency content or phase

  3. Modeling the early evolution of massive OB stars with an experimental wind routine. The first bi-stability jump and the angular momentum loss problem

    NASA Astrophysics Data System (ADS)

    Keszthelyi, Z.; Puls, J.; Wade, G. A.

    2017-01-01

    Context. Stellar evolution models of massive stars are very sensitive to the adopted mass-loss scheme. The magnitude and evolution of mass-loss rates significantly affect the main sequence evolution, and the properties of post-main sequence objects, including their rotational velocities. Aims: Driven by potential discrepancies between theoretically predicted and observationally derived mass-loss rates in the OB star range, we aim in particular to investigate the response to mass-loss rates that are lower than currently adopted, in parallel with the mass-loss behavior at the "first" bi-stability jump. Methods: We performed 1D hydrodynamical model calculations of single 20-60 M⊙ Galactic (Z = 0.014) stars where the effects of stellar winds are already significant in the main sequence phase. We have developed an experimental wind routine to examine the behavior and response of the models under the influence of different mass-loss rates. This observationally guided, simple and flexible wind routine is not a new mass-loss description but a useful tool based on the wind-momentum luminosity relation and other scaling relations, and provides a meaningful base for various tests and comparisons. Results: The main result of this study indicates a dichotomy between solutions of currently debated problems regarding mass-loss rates of hot massive stars. In a fully diffusive approach, and for commonly adopted initial rotational velocities, lower mass-loss rates than theoretically predicted require to invoke an additional source of angular momentum loss (either due to bi-stability braking, or yet unidentified) to brake down surface rotational velocities. On the other hand, a large jump in the mass-loss rates due to the bi-stability mechanism (a factor of 5-7 predicted by Vink et al. (2000, A&A, 362, 295), but a factor of 10-20 in modern models of massive stars) is challenged by observational results, and might be avoided if the early mass-loss rates agreed with the theoretically

  4. Holocene temperature variations at a high-altitude site in the Eastern Alps: a chironomid record from Schwarzsee ob Sölden, Austria.

    PubMed

    Ilyashuk, Elena A; Koinig, Karin A; Heiri, Oliver; Ilyashuk, Boris P; Psenner, Roland

    2011-01-01

    Few well-dated, quantitative Holocene temperature reconstructions exist from high-altitude sites in the Central Eastern Alps. Here, we present a chironomid-based quantitative reconstruction of mean July air temperatures (T(July)) throughout the Holocene for a remote high-mountain lake, Schwarzsee ob Sölden, situated above the treeline at 2796 m a.s.l. in the Austrian Alps. Applying a chironomid-temperature inference model developed from lakes of the Alpine region to a high-resolution chironomid record from the lake provides evidence for early Holocene (ca 10000-8600 cal yr BP) T(July) of up to 8.5 °C, i.e. >4 °C above the modern (1977-2006) mean July temperature. The reconstruction reveals the so-called '8.2-ka cold event' centered at ca 8250-8000 cal yr BP with temperatures ca 3 °C below the early-Holocene thermal maximum. Rather warm (ca 6 °C) and productive conditions prevailed during ca 7900-4500 cal yr BP. The chironomid record suggests a climate transition between ca 5200 and 4500 cal yr BP to cooler T(July). A distinct cooling trend is evident from ca 4500 until ca 2500 cal yr BP. Thereafter, the study site experienced its coldest conditions (around 4 °C or less) throughout the rest of the Holocene, with the exception of the warming trend during the late 20th century. Beside other factors, the Northern Hemisphere summer insolation seems to be the major driving force for the long-term trends in T(July) at high altitudes in the Eastern Alps. Due to the extreme location of the lake and the limited temperature range represented by the applied calibration data set, the chironomid-based temperature reconstruction fails to track phases of the late-Holocene climatic history with T(July) cooler than 4 °C. Further chironomid-based palaeoclimate model and down-core studies are required to address this problem, provide more realistic T(July) estimates from undisturbed high-altitude lakes in the Alps, and extract a reliable regional

  5. Methane monooxygenase from Methylosinus trichosporium OB3b. Purification and properties of a three-component system with high specific activity from a type II methanotroph.

    PubMed

    Fox, B G; Froland, W A; Dege, J E; Lipscomb, J D

    1989-06-15

    Methane monooxygenase has been purified from the Type II methanotroph Methylosinus trichosporium OB3b. As observed for methane monooxygenase isolated from Type I methanotrophs, three protein components are required: a 39.7-kDa NADH reductase containing 1 mol each of FAD and a [2Fe-2S] cluster, a 15.8-kDa protein factor termed component B that contains no metals or cofactors, and a 245-kDa hydroxylase which appears to contain an oxo- or hydroxo-bridged binuclear iron cluster. Through the use of stabilizing reagents, the hydroxylase is obtained in high yield and exhibits a specific activity 8-25-fold greater than reported for previous preparations. The component B and reductase exhibit 1.5- and 4-fold greater specific activity, respectively. Quantitation of the hydroxylase oxo-bridged cluster using EPR and Mössbauer spectroscopies reveals that the highest specific activity preparations (approximately 1700 nmol/min/mg) contain approximately 2 clusters/mol. In contrast, hydroxylase preparations exhibiting a wide range of specific activities below 500 nmol/min/mg contain approximately 1 cluster/mol on average. Efficient turnover coupled to NADH oxidation requires all three protein components. However, both alkanes and alkenes are hydroxylated by the chemically reduced hydroxylase under single turnover conditions in the absence of component B and the reductase. Neither of these components catalyzes hydroxylation individually nor do they significantly affect the yield of hydroxylated product from the chemically reduced hydroxylase. Hydroxylase reduced only to the mixed valent [Fe(II).Fe(III)] state is unreactive toward O2 and yields little hydroxylated product on single turnover. This suggests that the catalytically active species is the fully reduced form. The data presented here provide the first evidence based on catalysis that the site of the monooxygenation reaction is located on the hydroxylase. It thus appears likely that the oxo-bridged iron cluster is capable of

  6. Holocene temperature variations at a high-altitude site in the Eastern Alps: a chironomid record from Schwarzsee ob Sölden, Austria

    PubMed Central

    Ilyashuk, Elena A.; Koinig, Karin A.; Heiri, Oliver; Ilyashuk, Boris P.; Psenner, Roland

    2011-01-01

    Few well-dated, quantitative Holocene temperature reconstructions exist from high-altitude sites in the Central Eastern Alps. Here, we present a chironomid-based quantitative reconstruction of mean July air temperatures (TJuly) throughout the Holocene for a remote high-mountain lake, Schwarzsee ob Sölden, situated above the treeline at 2796 m a.s.l. in the Austrian Alps. Applying a chironomid-temperature inference model developed from lakes of the Alpine region to a high-resolution chironomid record from the lake provides evidence for early Holocene (ca 10000–8600 cal yr BP) TJuly of up to 8.5 °C, i.e. >4 °C above the modern (1977–2006) mean July temperature. The reconstruction reveals the so-called ‘8.2-ka cold event’ centered at ca 8250–8000 cal yr BP with temperatures ca 3 °C below the early-Holocene thermal maximum. Rather warm (ca 6 °C) and productive conditions prevailed during ca 7900–4500 cal yr BP. The chironomid record suggests a climate transition between ca 5200 and 4500 cal yr BP to cooler TJuly. A distinct cooling trend is evident from ca 4500 until ca 2500 cal yr BP. Thereafter, the study site experienced its coldest conditions (around 4 °C or less) throughout the rest of the Holocene, with the exception of the warming trend during the late 20th century. Beside other factors, the Northern Hemisphere summer insolation seems to be the major driving force for the long-term trends in TJuly at high altitudes in the Eastern Alps. Due to the extreme location of the lake and the limited temperature range represented by the applied calibration data set, the chironomid-based temperature reconstruction fails to track phases of the late-Holocene climatic history with TJuly cooler than 4 °C. Further chironomid-based palaeoclimate model and down-core studies are required to address this problem, provide more realistic TJuly estimates from undisturbed high-altitude lakes in the Alps, and extract a reliable regional

  7. Using sequential extraction techniques to assess the partitioning of plutonium and neptunium-237 from multiple sources in sediments from the Ob River (Siberia).

    PubMed

    Kenna, Timothy C

    2009-07-01

    refractory fractions ranged between 0.11 and 0.18. With the exception of one sample, the (240)Pu/(239)Pu isotope ratios measured in the refractory fractions are essentially identical having a mean ratio value of 0.123+/-0.001 (1sigma). The (240)Pu/(239)Pu ratios provide isotopic evidence that suggests a portion of non-fallout contamination has a refractory nature. The presence of similarly low (240)Pu/(239)Pu ratios in refractory fractions of sediments from the Ob and Irtysh Rivers suggests the existence of a source of refractory Pu which is consistent with refractory "hot particles" derived from surface tests at the Semipalitinsk test site.

  8. The virtual observatory service TheoSSA: Establishing a database of synthetic stellar flux standards . II. NLTE spectral analysis of the OB-type subdwarf Feige 110

    NASA Astrophysics Data System (ADS)

    Rauch, T.; Rudkowski, A.; Kampka, D.; Werner, K.; Kruk, J. W.; Moehler, S.

    2014-06-01

    Context. In the framework of the Virtual Observatory (VO), the German Astrophysical VO (GAVO) developed the registered service TheoSSA (Theoretical Stellar Spectra Access). It provides easy access to stellar spectral energy distributions (SEDs) and is intended to ingest SEDs calculated by any model-atmosphere code, generally for all effective temperatures, surface gravities, and elemental compositions. We will establish a database of SEDs of flux standards that are easily accessible via TheoSSA's web interface. Aims: The OB-type subdwarf Feige 110 is a standard star for flux calibration. State-of-the-art non-local thermodynamic equilibrium stellar-atmosphere models that consider opacities of species up to trans-iron elements will be used to provide a reliable synthetic spectrum to compare with observations. Methods: In case of Feige 110, we demonstrate that the model reproduces not only its overall continuum shape from the far-ultraviolet (FUV) to the optical wavelength range but also the numerous metal lines exhibited in its FUV spectrum. Results: We present a state-of-the-art spectral analysis of Feige 110. We determined , log g = 6.00 ± 0.20, and the abundances of He, N, P, S, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, and Ge. Ti, V, Mn, Co, Zn, and Ge were identified for the first time in this star. Upper abundance limits were derived for C, O, Si, Ca, and Sc. Conclusions: The TheoSSA database of theoretical SEDs of stellar flux standards guarantees that the flux calibration of astronomical data and cross-calibration between different instruments can be based on models and SEDs calculated with state-of-the-art model-atmosphere codes. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26666. Based on observations made with the NASA-CNES-CSA Far Ultraviolet Spectroscopic Explorer. Table 2, Figs. 3 and

  9. The substrate binding cavity of particulate methane monooxygenase from Methylosinus trichosporium OB3b expresses high enantioselectivity for n-butane and n-pentane oxidation to 2-alcohol.

    PubMed

    Miyaji, Akimitsu; Miyoshi, Teppei; Motokura, Ken; Baba, Toshihide

    2011-11-01

    The particulate methane monooxygenase (pMMO) of Methylosinus trichosporium OB3b oxidized n-butane and n-pentane and mainly produced (R)-2-butanol and (R)-2-pentanol that comprised 78 and 89% of the product, respectively, indicating that the pro-R hydrogen of the 2-position carbon of n-butane and n-pentane is oriented toward a catalytic site within the substrate binding site of pMMO. The protein cavity adjacent to the catalytic center for pMMO has optimum volume for recognizing n-butane and n-pentane for enantioselective hydroxylation.

  10. A REVISED AGE FOR UPPER SCORPIUS AND THE STAR FORMATION HISTORY AMONG THE F-TYPE MEMBERS OF THE SCORPIUS-CENTAURUS OB ASSOCIATION

    SciTech Connect

    Pecaut, Mark J.; Mamajek, Eric E.; Bubar, Eric J.

    2012-02-20

    We present an analysis of the ages and star formation history of the F-type stars in the Upper Scorpius (US), Upper Centaurus-Lupus (UCL), and Lower Centaurus-Crux (LCC) subgroups of Scorpius-Centaurus (Sco-Cen), the nearest OB association. Our parent sample is the kinematically selected Hipparcos sample of de Zeeuw et al., restricted to the 138 F-type members. We have obtained classification-resolution optical spectra and have also determined the spectroscopic accretion disk fraction. With Hipparcos and 2MASS photometry, we estimate the reddening and extinction for each star and place the candidate members on a theoretical H-R diagram. For each subgroup we construct empirical isochrones and compare to published evolutionary tracks. We find that (1) our empirical isochrones are consistent with the previously published age-rank of the Sco-Cen subgroups; (2) subgroups LCC and UCL appear to reach the main-sequence turn-on at spectral types {approx}F4 and {approx}F2, respectively. An analysis of the A-type stars shows US reaching the main sequence at about spectral type {approx}A3. (3) The median ages for the pre-main-sequence members of UCL and LCC are 16 Myr and 17 Myr, respectively, in agreement with previous studies, however we find that (4) Upper Sco is much older than previously thought. The luminosities of the F-type stars in US are typically a factor of {approx}2.5 less luminous than predicted for a 5 Myr old population for four sets of evolutionary tracks. We re-examine the evolutionary state and isochronal ages for the B-, A-, and G-type Upper Sco members, as well as the evolved M supergiant Antares, and estimate a revised mean age for Upper Sco of 11 {+-} 1 {+-} 2 Myr (statistical, systematic). Using radial velocities and Hipparcos parallaxes we calculate a lower limit on the kinematic expansion age for Upper Sco of >10.5 Myr (99% confidence). However, the data are statistically consistent with no expansion. We reevaluate the inferred masses for the known

  11. A parallel algorithm for 2D visco-acoustic frequency-domain full-waveform inversion: application to a dense OBS data set

    NASA Astrophysics Data System (ADS)

    Sourbier, F.; Operto, S.; Virieux, J.

    2006-12-01

    computes the corresponding sub-domain of the gradient. In the end, the gradient is centralized on the master processor using a collective communation. The gradient is scaled by the diagonal elements of the Hessian matrix. This scaling is computed only once per frequency before the first iteration of the inversion. Estimation of the diagonal terms of the Hessian requires performing one simulation per non redondant shot and receiver position. The same strategy that the one used for the gradient is used to compute the diagonal Hessian in parallel. This algorithm was applied to a dense wide-angle data set recorded by 100 OBSs in the eastern Nankai trough, offshore Japan. Thirteen frequencies ranging from 3 and 15 Hz were inverted. Tweny iterations per frequency were computed leading to 260 tomographic velocity models of increasing resolution. The velocity model dimensions are 105 km x 25 km corresponding to a finite-difference grid of 4201 x 1001 grid with a 25-m grid interval. The number of shot was 1005 and the number of inverted OBS gathers was 93. The inversion requires 20 days on 6 32-bits bi-processor nodes with 4 Gbytes of RAM memory per node when only the LU factorization is performed in parallel. Preliminary estimations of the time required to perform the inversion with the fully-parallelized code is 6 and 4 days using 20 and 50 processors respectively.

  12. A Revised Age for Upper Scorpius and the Star Formation History among the F-type Members of the Scorpius-Centaurus OB Association

    NASA Astrophysics Data System (ADS)

    Pecaut, Mark J.; Mamajek, Eric E.; Bubar, Eric J.

    2012-02-01

    We present an analysis of the ages and star formation history of the F-type stars in the Upper Scorpius (US), Upper Centaurus-Lupus (UCL), and Lower Centaurus-Crux (LCC) subgroups of Scorpius-Centaurus (Sco-Cen), the nearest OB association. Our parent sample is the kinematically selected Hipparcos sample of de Zeeuw et al., restricted to the 138 F-type members. We have obtained classification-resolution optical spectra and have also determined the spectroscopic accretion disk fraction. With Hipparcos and 2MASS photometry, we estimate the reddening and extinction for each star and place the candidate members on a theoretical H-R diagram. For each subgroup we construct empirical isochrones and compare to published evolutionary tracks. We find that (1) our empirical isochrones are consistent with the previously published age-rank of the Sco-Cen subgroups; (2) subgroups LCC and UCL appear to reach the main-sequence turn-on at spectral types ~F4 and ~F2, respectively. An analysis of the A-type stars shows US reaching the main sequence at about spectral type ~A3. (3) The median ages for the pre-main-sequence members of UCL and LCC are 16 Myr and 17 Myr, respectively, in agreement with previous studies, however we find that (4) Upper Sco is much older than previously thought. The luminosities of the F-type stars in US are typically a factor of ~2.5 less luminous than predicted for a 5 Myr old population for four sets of evolutionary tracks. We re-examine the evolutionary state and isochronal ages for the B-, A-, and G-type Upper Sco members, as well as the evolved M supergiant Antares, and estimate a revised mean age for Upper Sco of 11 ± 1 ± 2 Myr (statistical, systematic). Using radial velocities and Hipparcos parallaxes we calculate a lower limit on the kinematic expansion age for Upper Sco of >10.5 Myr (99% confidence). However, the data are statistically consistent with no expansion. We reevaluate the inferred masses for the known substellar companions in Upper Sco