oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 183 )

2018 ( 320 )

2017 ( 296 )

2016 ( 455 )

Custom range...

Search Results: 1 - 10 of 297640 matches for " Beverly J. Cowart "
All listed articles are free for downloading (OA Articles)
Page 1 /297640
Display every page Item
Assessment of smoking status based on cotinine levels in nasal lavage fluid
Mehmet Ozdener, Karen K Yee, Ryan McDermott, Beverly J Cowart, Aldona A Vainius, Pamela Dalton, Nancy E Rawson
Tobacco Induced Diseases , 2009, DOI: 10.1186/1617-9625-5-11
Abstract: Precise estimation of direct exposure to tobacco smoke is a problem for epidemiologic studies due to human errors and inaccuracy in self report. Assessment of passive exposure to tobacco smoke is even more problematic [1,2]. While nicotine has a relatively short half-life of about 2 hours, cotinine, a principal metabolite of nicotine, has a half-life of approximately 20 hours, and is a specific and sensitive marker for determining exposure to tobacco [3-5]. Therefore, measurement of salivary, urinary or serum cotinine values have been used to validate self-reported smoking status [1,4], with saliva providing the most easily obtained source [6-8].Notably, the olfactory sensory neuroepithelium and nasal mucosa are directly exposed to tobacco smoke in both smokers and non-smokers who live with or work around smokers. Smoking has been shown to reduce olfactory sensitivity in a dose- and time-dependent manner [9-12], and passive smoke exposure has been implicated in reduced olfactory function as well [13]. Using nicotine nasal spray caused adverse effects of nasal irritation and burning and taste and smell complaints [14]. Moreover, both exposures to tobacco smoke and to lipopolysaccharide, an active component of cigarette smoke, trigger a dramatic increase in the degree of olfactory neuron apoptosis [15,16].The impact of smoking on the nasal mucosa has received considerably less study than its impact on lower respiratory tissue. Nonetheless, there is evidence for multiple deleterious effects, including increased nasal resistance, decreased mucociliary flow and mucosal sensitivity, and induces increase in DNA adduct and may cause nasal tumors due to numerous chemicals found [17,18]. Histopathological analysis of nasal mucosa obtained from rats exposed to tobacco smoke revealed a decrease in the extent of olfactory epithelium including loss of cilia and development of metaplasia [19].Tobacco smoke may exert direct effects on nasal epithelial health and olfactory neuronal
Sour Ageusia in Two Individuals Implicates Ion Channels of the ASIC and PKD Families in Human Sour Taste Perception at the Anterior Tongue
Taufiqul Huque, Beverly J. Cowart, Luba Dankulich-Nagrudny, Edmund A. Pribitkin, Douglas L. Bayley, Andrew I. Spielman, Roy S. Feldman, Scott A. Mackler, Joseph G. Brand
PLOS ONE , 2009, DOI: 10.1371/journal.pone.0007347
Abstract: Background The perception of sour taste in humans is incompletely understood at the receptor cell level. We report here on two patients with an acquired sour ageusia. Each patient was unresponsive to sour stimuli, but both showed normal responses to bitter, sweet, and salty stimuli. Methods and Findings Lingual fungiform papillae, containing taste cells, were obtained by biopsy from the two patients, and from three sour-normal individuals, and analyzed by RT-PCR. The following transcripts were undetectable in the patients, even after 50 cycles of amplification, but readily detectable in the sour-normal subjects: acid sensing ion channels (ASICs) 1a, 1β, 2a, 2b, and 3; and polycystic kidney disease (PKD) channels PKD1L3 and PKD2L1. Patients and sour-normals expressed the taste-related phospholipase C-β2, the δ-subunit of epithelial sodium channel (ENaC) and the bitter receptor T2R14, as well as β-actin. Genomic analysis of one patient, using buccal tissue, did not show absence of the genes for ASIC1a and PKD2L1. Immunohistochemistry of fungiform papillae from sour-normal subjects revealed labeling of taste bud cells by antibodies to ASICs 1a and 1β, PKD2L1, phospholipase C-β2, and δ-ENaC. An antibody to PKD1L3 labeled tissue outside taste bud cells. Conclusions These data suggest a role for ASICs and PKDs in human sour perception. This is the first report of sour ageusia in humans, and the very existence of such individuals (“natural knockouts”) suggests a cell lineage for sour that is independent of the other taste modalities.
Shoreline Change along Sheltered Coastlines: Insights from the Neuse River Estuary, NC, USA
Lisa Cowart,D. Reide Corbett,J.P. Walsh
Remote Sensing , 2011, DOI: 10.3390/rs3071516
Abstract: Coastlines are constantly changing due to both natural and anthropogenic forces, and climate change and associated sea level rise will continue to reshape coasts in the future. Erosion is not only apparent along oceanfront areas; shoreline dynamics in sheltered water bodies have also gained greater attention. Additional estuarine shoreline studies are needed to better understand and protect coastal resources. This study uses a point-based approach to analyze estuarine shoreline change and associated parameters, including fetch, wave energy, elevation, and vegetation, in the Neuse River Estuary (NRE) at two contrasting scales, Regional (whole estuary) and Local (estuary partitioned into eight sections, based on orientation and exposure). With a mean shoreline-change rate of –0.58 m yr?1, the majority (93%) of the NRE study area is eroding. Change rates show some variability related to the land-use land-cover classification of the shoreline. Although linear regression analysis at the Regional Scale did not find significant correlations between shoreline change and the parameters analyzed, trends were determined from Local Scale data. Specifically, erosion rates, fetch, and wave exposure increase in the down-estuary direction, while elevation follows the opposite trend. Linear regression analysis between mean fetch and mean shoreline-change rates at the Local Scale provide a first-order approach to predict shoreline-change rates. The general trends found in the Local Scale data highlight the presence of underlying spatial patterns in shoreline-change rates within a complex estuarine system, but Regional Scale analysis suggests shoreline composition also has an important influence.
The Gender System and Fertility: An Exploration of the Hidden Links
Beverly J. Matthews
Canadian Studies in Population , 1999,
Abstract:
Interstellar Gas in the NGC 4410 Galaxy Group
Beverly J. Smith
Physics , 2000, DOI: 10.1086/309448
Abstract: We present new radio continuum, 21 cm HI, and 2.6 mm CO data for the peculiar radio galaxy NGC 4410A and its companion NGC 4410B, and compare with available optical and X-ray maps. Our radio continuum maps show an asymmetric double-lobedstructure, with a high surface brightness lobe extending 3.6 arcmin (~100 kpc) to the southeast and a 6.2 arcmin (~180 kpc) low surface brightness feature in the northwest. Molecular gas is abundant in NGC 4410A, with M(H2) ~ 4 X 10^9 M(sun) (using the standard Galactic conversion factor), but is undetected in NGC 4410B. HI is less abundant, with M(HI) ~ 10^9 M(sun) for the pair. Our HI map shows a 3 X 10^8 M(sun) HI tail extending 1.7 arcmin (50 kpc) to the southeast of the pair, coincident with a faint optical tail and partially overlapping with the southeastern radio lobe. The HI tail is anti-coincident with a 2' (56 kpc) long X-ray structure aligned with a stellar bridge that connects the pair to a third galaxy. If this X-ray emission is associated with the group, there is 3 - 8 X 10^8 M(sun) of hot gas in this feature: either intracluster gas or shocked gas associated with the bridge. Our detection of abundant interstellar gas in this pair suggests that the distortions in this lobe map have been caused by the interstellar medium in this system. The interaction of the two galaxies and the subsequent motion of the interstellar medium in the system relative to the jet may have produced sufficient ram pressure to bend the radio jet. An alternative hypothesis is that the jet was distorted by ram pressure due to an intracluster medium, although the small radial velocity of NGC 4410A relative to the group and the lack of diffuse X-ray emission in the group makes this less likely unless the group is not virialized or is in the process of merging with another group.
Infrared Colors and Variability of Evolved Stars from COBE DIRBE Data
Beverly J. Smith
Physics , 2003, DOI: 10.1086/376743
Abstract: For a complete 12 micron flux-limited sample of 207 IRAS sources, we have extracted light curves in seven infrared bands between 1.25 - 60 microns using the database of the DIRBE instrument on the COBE satellite. Using previous infrared surveys, we filtered these light curves to remove datapoints affected by nearby companions. In the time-averaged DIRBE color-color plots, we find clear segregation of semi-regulars, Mira variables, carbon stars, OH/IR stars, and red giants without circumstellar dust and with little or no visual variation. The DIRBE 1.25 - 25 micron colors become progressively redder and the variability in the DIRBE database increases along the oxygen-rich sequence non-dusty slightly varying red giants -> SRb/Lb -> SRa -> Mira -> OH/IR and the carbon-rich SRb/Lb -> Mira sequence. This supports previous assertions that these are evolutionary sequences involving the continued production and ejection of dust. Carbon stars are redder than oxygen-rich stars for the same variability type, except in the F(12)/F(25) ratio. Of the 28 sources in the sample not previous noted to be variable, 18 are clearly variable in the DIRBE data, with amplitudes of variation of ~0.9 magnitudes at 4.9 microns and ~0.6 magnitudes at 12 microns, consistent with them being very dusty Mira-like variables. The light curves of the semi-regular variable L2 Pup are particularly remarkable. The maxima at 1.25, 2.2, and 3.5 microns occur 10 - 20 days before those at 4.9 and 12 microns, and, at 4.9 and 12 microns, another maximum is seen between the two near-infrared maxima.
ISOCAM Mid-Infrared Imaging of the Quiescent Spiral Galaxy NGC 7331
Beverly J. Smith
Physics , 1998, DOI: 10.1086/305733
Abstract: Using the mid-infrared camera (ISOCAM) on the Infrared Space Observatory (ISO), the Sb LINER galaxy NGC 7331 has been imaged in two broadband and four narrowband filters between 6.75 and 15 microns. These maps show a prominent circumnuclear ring of radius 0.25 arcminutes X 0.75 arcminutes (1.1 X 3.3 kpc) encircling an extended central source. The 7.7 and 11.3 micron dust emission features are strong in this galaxy, contributing approximately 1/3 of the total IRAS 12 micron broadband flux from this galaxy. In contrast to starburst galaxies, the 15 micron continuum is weak in NGC 7331. The mid-infrared spectrum does not vary dramatically with position in this quiescent galaxy, showing neither large-scale destruction of the carriers of the emission bands or a large increase in the 15 micron continuum in the star forming ring. In the bulge, there is some enhancement of the 6.75 micron flux, probably because of contributions from photospheric light, however, the 11.3 micron dust feature is also seen, showing additional emission from interstellar or circumstellar dust.
The Origin of the 4.5 micron Excess from Dwarf Galaxies
Beverly J. Smith,Mark Hancock
Physics , 2009, DOI: 10.1088/0004-6256/138/1/130
Abstract: Dwarf galaxies tend to have redder [3.6 micron] - [4.5 micron] Spitzer broadband colors than spirals. To investigate this effect, for a large sample of dwarf galaxies we combine Spitzer fluxes with data at other wavelengths and compare to population synthesis models. Lower metallicity systems are found to have redder [3.6] - [4.5] colors on average, but with considerable scatter. The observed range in [3.6] - [4.5] color is too large to be accounted for solely by variations in stellar colors due to age or metallicity differences; interstellar effects must contribute as well. For the reddest systems, the 4.5 micron luminosity may not be a good tracer of stellar mass. We identify three factors that redden this color in dwarfs. First, in some systems, strong Br-alpha emission contributes significantly to the 4.5 micron emission. Second, in some cases high optical depths lead to strong reddening of the starlight in the Spitzer bands. Third, in some galaxies, the nebular continuum dominates the 4.5 micron flux, and in extreme cases, the 3.6 micron flux as well. The harder UV radiation fields in lower metallicity systems produce both more gaseous continuum in the infrared and more Br-alpha per star formation rate. The combination of these three factors can account for the 4.5 micron excess in our sample galaxies, thus it is not necessary to invoke a major contribution from hot dust to the 4.5 micron band. However, given the uncertainties, we are not able to completely rule out hot dust emission at 4.5 micron. More spectroscopic observations in the 3 - 5 micron range are needed to disentangle these effects.
Models of the Morphology, Kinematics, and Star Formation History of the Prototypical Collisional Starburst System: NGC 7714/7715 = Arp 284
Curtis Struck,Beverly J. Smith
Physics , 2003, DOI: 10.1086/374586
Abstract: (abridged) We present new N-body, hydrodynamical simulations of the interaction between the starburst galaxy NGC 7714 and its post-starburst companion NGC 7715, focusing on the formation of the collisional features, including: 1) the gas-rich star forming bridge, 2) the large gaseous loop (and stellar tails) to the west of the system, 3) the very extended HI tail to the west and north of NGC 7714, and 4) the partial stellar ring in NGC 7714. Our simulations confirm the results of earlier work that an off-center inclined collision between two disk galaxies is almost certainly responsible for the peculiar morphologies of this system. However, we have explored a wider set of initial galaxy and collisional encounter parameters than previously, and have found a relatively narrow range of parameters that reproduce all the major morphologies of this system. The simulations suggest specific mechanisms for the development of several unusual structures. We find that the complex gas bridge has up to four distinct components, with gas contributed from two sides of NGC 7715, as well as from NGC 7714. The observed gas-star offset in this bridge is accounted for in the simulations by the dissipative evolution of the gas. The models also indicate that the low surface brightness HI tail to the far west of NGC 7714 is the end of the NGC 7715 countertail, curved behind the two galaxies. Spectral evolutionary models of the NGC 7714 core by Lan\c{c}on et al. suggest the possibility of multiple starbursts in the last 300 Myr. Our hydrodynamic models suggest that bursts could be triggered by induced ring-like waves, and a post-collision buildup of gas in the core of the galaxy.
The symmetries and scaling of tidal tails in galaxies
Curtis Struck,Beverly J. Smith
Physics , 2012, DOI: 10.1111/j.1365-2966.2012.20798.x
Abstract: (Abriged) We present analytic models for the formation and evolution of tidal tails and related structures following impulsive disturbances in galaxy collisions. Since the epicyclic approximation is not valid for large radial excursions, we use orbital equations of the form we call p-ellipses. These have been shown to provide accurate representations of orbits in power-law halo potentials. In the case of a purely tidal disturbance the resulting tidal tails have simple structure. Scalings for their maximum lengths and other characteristics as functions of the tidal amplitude and the exponent of the power-law potentials are described. The analytic model shows that azimuthal caustics (orbit crossing zones) are produced generically in these tails at a fixed azimuth relative to the point of closest approach. Long tails, with high order caustics at their base are also produced at larger amplitudes. The analysis is extended to nonlinear disturbances and multiple encounters, which break the symmetries of tidal perturbations. As the strength of the nonlinear terms is varied the structure of the resulting forms varies from symmetric tails to one-armed plumes. Cases with two or more impulse disturbances are also considered as the simplest analytic models distinguishing between prograde and retrograde encounters. A specific mechanism for the formation of tidal dwarf galaxies at the end of tails is suggested as a consequence of resonance effects in prolonged encounters. Qualitative comparisons to Arp Atlas systems suggest that the limiting analytic cases are realized in real systems. We identify a few Arp systems which may have swallowtail caustics, where dissipative gas streams converge and trigger star formation. UV and optical images reveal luminous knots of young stars at these 'hinge clump' locations.
Page 1 /297640
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.