182 research outputs found

    Vibrational Spectrum of N‐Methyl Formamide

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70491/2/JCPSA6-26-3-716-2.pd

    Augmenter of liver regeneration enhances the success rate of fetal pancreas transplantation in rodents

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    Background. Treatment of fetal pancreas (FP) isografts with insulin- like growth factor-I greatly improves the rate of conversion to euglycemia in diabetic rats. Complete knowledge of other factors that may facilitate the engraftment and function of FP in vivo is still embryonic. Augmenter of liver regeneration (ALR) is a newly described polypeptide growth factor found in weanling rat livers. ALR has trophic effects on regenerating liver. We studied the effects of in situ administration of this agent on FP isografts in rats. Methods. Streptozotocin-diabetic Lewis rats (blood glucose >300 mg/dl) received 16 FP isografts transplanted intramuscularly. ALR was delivered from day 1 through day 14, in doses of 40 or 400 ng/kg/d. Animals were followed for 3 months with serial weights and blood glucose monitoring. These animals were compared with those treated with vehicle alone. Results. Of the group treated with ALR at 40 ng/kg/day for 14 days, 89% (eight of nine) were euglycemic (P=0.0003). Of the group treated with ALR at 400 ng/kg/day for 14 days, 88% (seven of eight) were euglycemic (P=0.0007). Of the group treated with vehicle alone, none of the six were euglycemic. Euglycemia is defined here as glucose<200 mg/dl for 3 days. Pathology of the intramuscular transplant site showed patches of islet tissue embedded in fat. These patches demonstrated insulin immunoreactivity. Conclusions. Diabetes was reversed in a significantly greater proportion of FP + ALR-treated recipients than those animals treated with vehicle alone. Local delivery of growth factors my be used as an adjunct to FP transplantation to improve the rate of success. This in situ model may be useful to further evaluate other soluble factors

    The WARPS Survey: VI. Galaxy Cluster and Source Identifications from Phase I

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    We present in catalog form the optical identifications for objects from the first phase of the Wide Angle ROSAT Pointed Survey (WARPS). WARPS is a serendipitous survey of relatively deep, pointed ROSAT observations for clusters of galaxies. The X-ray source detection algorithm used by WARPS is Voronoi Tessellation and Percolation (VTP), a technique which is equally sensitive to point sources and extended sources of low surface brightness. WARPS-I is based on the central regions of 86 ROSAT PSPC fields, covering an area of 16.2 square degrees. We describe here the X-ray source screening and optical identification process for WARPS-I, which yielded 34 clusters at 0.06<z<0.75. Twenty-two of these clusters form a complete, statistically well defined sample drawn from 75 of these 86 fields, covering an area of 14.1 square degrees, with a flux limit of F (0.5-2.0 keV) = 6.5 \times 10^{-14} erg cm^{-2} s^{-1}}. This sample can be used to study the properties and evolution of the gas, galaxy and dark matter content of clusters, and to constrain cosmological parameters. We compare in detail the identification process and findings of WARPS to those from other recently published X-ray surveys for clusters, including RDCS, SHARC-Bright, SHARC-south and the CfA 160 deg2^2 survey.Comment: v3 reflects minor updates to tables 2 and

    The C4 Clustering Algorithm: Clusters of Galaxies in the Sloan Digital Sky Survey

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    We present the "C4 Cluster Catalog", a new sample of 748 clusters of galaxies identified in the spectroscopic sample of the Second Data Release (DR2) of the Sloan Digital Sky Survey (SDSS). The C4 cluster--finding algorithm identifies clusters as overdensities in a seven-dimensional position and color space, thus minimizing projection effects which plagued previous optical clusters selection. The present C4 catalog covers ~2600 square degrees of sky with groups containing 10 members to massive clusters having over 200 cluster members with redshifts. We provide cluster properties like sky location, mean redshift, galaxy membership, summed r--band optical luminosity (L_r), velocity dispersion, and measures of substructure. We use new mock galaxy catalogs to investigate the sensitivity to the various algorithm parameters, as well as to quantify purity and completeness. These mock catalogs indicate that the C4 catalog is ~90% complete and 95% pure above M_200 = 1x10^14 solar masses and within 0.03 <=z <= 0.12. The C4 algorithm finds 98% of X-ray identified clusters and 90% of Abell clusters within 0.03 <= z <= 0.12. We show that the L_r of a cluster is a more robust estimator of the halo mass (M_200) than the line-of-sight velocity dispersion or the richness of the cluster. L_r. The final SDSS data will provide ~2500 C4 clusters and will represent one of the largest and most homogeneous samples of local clusters.Comment: 32 pages of figures and text accepted in AJ. Electronic version with additional tables, links, and figures is available at http://www.ctio.noao.edu/~chrism/c

    Cluster Analysis of Obesity and Asthma Phenotypes

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    Asthma is a heterogeneous disease with variability among patients in characteristics such as lung function, symptoms and control, body weight, markers of inflammation, and responsiveness to glucocorticoids (GC). Cluster analysis of well-characterized cohorts can advance understanding of disease subgroups in asthma and point to unsuspected disease mechanisms. We utilized an hypothesis-free cluster analytical approach to define the contribution of obesity and related variables to asthma phenotype.In a cohort of clinical trial participants (n = 250), minimum-variance hierarchical clustering was used to identify clinical and inflammatory biomarkers important in determining disease cluster membership in mild and moderate persistent asthmatics. In a subset of participants, GC sensitivity was assessed via expression of GC receptor alpha (GCRα) and induction of MAP kinase phosphatase-1 (MKP-1) expression by dexamethasone. Four asthma clusters were identified, with body mass index (BMI, kg/m(2)) and severity of asthma symptoms (AEQ score) the most significant determinants of cluster membership (F = 57.1, p<0.0001 and F = 44.8, p<0.0001, respectively). Two clusters were composed of predominantly obese individuals; these two obese asthma clusters differed from one another with regard to age of asthma onset, measures of asthma symptoms (AEQ) and control (ACQ), exhaled nitric oxide concentration (F(E)NO) and airway hyperresponsiveness (methacholine PC(20)) but were similar with regard to measures of lung function (FEV(1) (%) and FEV(1)/FVC), airway eosinophilia, IgE, leptin, adiponectin and C-reactive protein (hsCRP). Members of obese clusters demonstrated evidence of reduced expression of GCRα, a finding which was correlated with a reduced induction of MKP-1 expression by dexamethasoneObesity is an important determinant of asthma phenotype in adults. There is heterogeneity in expression of clinical and inflammatory biomarkers of asthma across obese individuals. Reduced expression of the dominant functional isoform of the GCR may mediate GC insensitivity in obese asthmatics

    A Pair of Compact Red Galaxies at Redshift 2.38, Immersed in a 100 kpc Scale Ly-alpha Nebula

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    We present Hubble Space Telescope (HST) and ground-based observations of a pair of galaxies at redshift 2.38, which are collectively known as 2142-4420 B1 (Francis et al. 1996). The two galaxies are both luminous extremely red objects (EROs), separated by 0.8 arcsec. They are embedded within a 100 kpc scale diffuse Ly-alpha nebula (or blob) of luminosity ~10^44 erg/s. The radial profiles and colors of both red objects are most naturally explained if they are young elliptical galaxies: the most distant yet found. It is not, however, possible to rule out a model in which they are abnormally compact, extremely dusty starbursting disk galaxies. If they are elliptical galaxies, their stellar populations have inferred masses of ~10^11 solar masses and ages of ~7x10^8 years. Both galaxies have color gradients: their centers are significantly bluer than their outer regions. The surface brightness of both galaxies is roughly an order of magnitude greater than would be predicted by the Kormendy relation. A chain of diffuse star formation extending 1 arcsec from the galaxies may be evidence that they are interacting or merging. The Ly-alpha nebula surrounding the galaxies shows apparent velocity substructure of amplitude ~ 700 km/s. We propose that the Ly-alpha emission from this nebula may be produced by fast shocks, powered either by a galactic superwind or by the release of gravitational potential energy.Comment: 33 pages, 9 figures, ApJ in press (to appear in Jun 10 issue

    Quaternary geology of the Northern Great Plains

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    The Great Plains physiographic province lies east of the Rocky Mountains and extends from southern Alberta and Saskatchewan nearly to the United States-Mexico border. This chapter covers only the northern part of the unglaciated portion of this huge region, from Oklahoma almost to the United StatesCanada border, a portion that herein will be referred to simply as the Northern Great Plains (Fig. 1). This region is in the rain shadow of the Rocky Mountains. Isoheyets are roughly longitudinal, and mean annual precipitation decreases from about 750 mm at the southeastern margin to less than 380 mm in the western and northern parts (Fig. 2). Winters typically are cold with relatively little precipitation, mostly as snow; summers are hot with increased precipitation, chiefly associated with movement of Pacific and Arctic air masses into warm, humid air masses from the Gulf of Mexico. Vegetation is almost wholly prairie grassland, due to the semiarid, markedly seasonal climate. The Northern Great Plains is a large region of generally low relief sloping eastward from the Rocky Mountains toward the Missouri and Mississippi Rivers. Its basic bedrock structure is a broad syncline, punctuated by the Black Hills and a few smaller uplifts, and by structural basins such as the Williston, Powder River, and Denver-Julesburg Basins (Fig. 3). Its surface bedrock is chiefly Cretaceous and Tertiary sediments, with small areas of older rocks in the Black Hills, central Montana, and eastern parts of Wyoming, Kansas, and Oklahoma. During the Laramide orogeny (latest Cretaceous through Eocene), while the Rocky Mountains and Black Hills were rising, synorogenic sediments (frequently with large amounts of volcanic ash from volcanic centers in the Rocky Mountains) were deposited in the subsiding Denver-Julesburg, Powder River, and other basins. From Oligocene to Miocene time, sedimentation generally slowed with declining tectonism and volcanism in the Rocky Mountains. However, since the later Miocene, epeirogenic uplift, probably associated with the East Pacific Rise, affected the Great Plains and particularly the Rocky Mountains. During the last 10 m.y. the Rocky Mountain front has risen 1.5 to 2 km, and the eastern margin of the Great Plains 100 to 500 m (Gable and Hatton, 1983), with half to one-quarter of these amounts during the last 5 m.y. Thus, during the later Miocene the Great Plains became a huge aggrading piedmont sloping gently eastward from the Rocky Mountains and Black Hills, with generally eastward drainage, on which the Ogallala Formation and equivalents was deposited. The Ogallala underlies the High Plains Surface, the highest and oldest geomorphic surface preserved in this region. It has been completely eroded along some parts of the western margin of the region (e.g., the Colorado Piedmont), but eastward, it (and its equivalents, such as the Flaxville gravels in Montana) locally is preserved as caprock or buried by Quaternary sediments (Alden, 1924, 1932; Howard, 1960; Stanley, 1971, 1976; Pearl, 1971; Scott, 1982; Corner and Diffendal, 1983; Diffendal and Corner, 1984; Swinehart and others, 1985; Aber, 1985). During the Pliocene, regional aggradation slowly changed to dissection by the principal rivers. In the western part of the region the rivers flowed eastward, but the continental drainage divide Figure 3. Major bedrock structures of the Northern Great Plains. extended northeast from the Black Hills through central South Dakota, far south of its present position. The ancestral upper Missouri, Little Missouri, Yellowstone, and Cheyenne Rivers drained northeast to Hudson Bay, whereas the ancestral White, Platte, and Arkansas Rivers went to the Gulf of Mexico (Fig 4A). Their courses are marked by scattered surface and subsurface gravel remnants; in Montana and North Dakota, deposits of the preglacial Missouri River and its tributaries are buried deeply beneath glacial and other sediments (Howard, 1960; Bluemle, 1972)

    Using clay to control harmful algal blooms : deposition and resuspension of clay/algal flocs

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    Author Posting. © Elsevier B.V, 2005. This is the author's version of the work. It is posted here by permission of Elsevier B.V for personal use, not for redistribution. The definitive version was published in Harmful Algae 4 (2005): 123-138, doi:10.1016/j.hal.2003.12.008.Harmful algal blooms (HABs) may be legitimate targets for direct control or mitigation, due to their impacts on commercial fisheries and public health. One promising control strategy is the rapid sedimentation of HABs through flocculation with clay. The objective of this study was to evaluate flow environments in which such a control strategy might be effective in removing harmful algae from the water column and depositing a layer of clay/algal flocs on the sea floor. We simulated the natural environment in two laboratory flumes: a straight-channel “17-m flume” in which flocs settled in a still water column and a “racetrack flume” in which flocs settled in flow. The 17-m flume experiments were designed to estimate the critical bed shear stress for resuspension of flocs that had settled for different time periods. The racetrack flume experiments were designed to examine the deposition and repeated resuspension of flocs in a system with tidal increases in flow speed. All flume runs were conducted with the non-toxic dinoflagellate Heterocapsa triquetra and phosphatic clay (IMC-P4). We repeated the experiments with a coagulant, polyaluminum hydroxychloride (PAC), expected to enhance the removal efficiency of the clay. Our experiments indicated that at low flow speeds (≀ 10 cm s-1), phosphatic clay was effective at removing algal cells from the water column, even after repeated resuspension. Once a layer of flocs accumulated on the bed, the consolidation, or dewatering, of the layer over time increased the critical shear stress for resuspension (i.e. decreased erodibility). Resuspension of a 2-mm thick layer that settled for 3 hours in relatively low flow speeds (≀ 3 cm s-1) would be expected at bed shear stress of ~0.06-0.07 Pa, as compared to up to 0.09 Pa for a layer that was undisturbed for 9 or 24 hours. For the same experimental conditions, the addition of PAC decreased the removal efficiency of algal cells in flow and increased the erodibility of flocs from the bottom. By increasing the likelihood that flocs remain in suspension, the addition of PAC in field trials of clay dispersal might have greater impact on sensitive, filter-feeding organisms. Overall, our experiments suggest that the flow environment should be considered before using clay as a control strategy for HABs in coastal waters.This project was funded by the Florida Institute of Phosphate Research (Grant # 99-03-138), with facilities provided by the Rinehart Coastal Research Center at WHOI

    HETDEX pilot survey for emission-line galaxies - I. Survey design, performance, and catalog

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    We present a catalog of emission-line galaxies selected solely by their emission-line fluxes using a wide-field integral field spectrograph. This work is partially motivated as a pilot survey for the upcoming Hobby-Eberly Telescope Dark Energy Experiment (HETDEX). We describe the observations, reductions, detections, redshift classifications, line fluxes, and counterpart information for 397 emission-line galaxies detected over 169 sq.arcmin with a 3500-5800 Ang. bandpass under 5 Ang. full-width-half-maximum (FWHM) spectral resolution. The survey's best sensitivity for unresolved objects under photometric conditions is between 4-20 E-17 erg/s/sq.cm depending on the wavelength, and Ly-alpha luminosities between 3-6 E42 erg/s are detectable. This survey method complements narrowband and color-selection techniques in the search for high redshift galaxies with its different selection properties and large volume probed. The four survey fields within the COSMOS, GOODS-N, MUNICS, and XMM-LSS areas are rich with existing, complementary data. We find 104 galaxies via their high redshift Ly-alpha emission at 1.9<z<3.8, and the majority of the remainder objects are low redshift [OII]3727 emitters at z<0.56. The classification between low and high redshift objects depends on rest frame equivalent width, as well as other indicators, where available. Based on matches to X-ray catalogs, the active galactic nuclei (AGN) fraction amongst the Ly-alpha emitters (LAEs) is 6%. We also analyze the survey's completeness and contamination properties through simulations. We find five high-z, highly-significant, resolved objects with full-width-half-maximum sizes >44 sq.arcsec which appear to be extended Ly-alpha nebulae. We also find three high-z objects with rest frame Ly-alpha equivalent widths above the level believed to be achievable with normal star formation, EW(rest)>240 Ang.Comment: 45 pages, 36 figures, 5 tables, submitted to ApJ
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