1,052 research outputs found

    Stock assessment of juvenile sturgeons in the Iranian water of the Caspian Sea by bottom trawl survey

    Get PDF
    The sturgeon stock assessment was performed to aim at estimation of absolute and relative abundance and determination of species composition at lower 10 m depths using the Si-Sara2 RV vessel in the Iranian coasts of the Caspian Sea in Guilan, Mazandaran and Golestan provinces during 6-30 September 2011-2012. In this study, 40 stations were selected on the basis of stratified random sampling design and then the stock estimation was performed using the swept area method. The study was carried out using bottom trawling with 9 m head rope. The time and speed of trawling in each station were 30 minutes and 2.5 knots respectively. The Catch per Unit of Effort (CPUE) in 2011–2012 were 7.03 and 6.96 individuals per trawling, respectively. The catch per unit of area in these years were found to be 1662 and 1644 fish in nm2, respectively.Total abundance of sturgeon juveniles was 13,327,164 individuals in 2011. So, the species composition included A. persicus (87.8%) and A. stellatus (12.2%). Total abundance of sturgeon juveniles was found to be 14,364,882 individuals in 2012 and the species composition comprised A. persicus (61.4%) and A. stellatus (38.6%). In 2011 the biomass of sturgeons in Iranian coastal water of the Caspian Sea was 295 tons and the composition of biomass included A. persicus (81.5%) and A. stellatus (18.5%), respectively. In the cruises conducted in 2011, this amount was estimated to be 217 tons comprising A. persicus (54.2%) and A. stellatus (45.8%), respectively. The results of this study in 2011–2012 showed remarkable abundance of juvenile sturgeons in Iranian coastal waters of the Caspian Sea in late summer and early autumn. So, by conserving these valuable stocks, the number of spawners will be increased in the future

    Lorentz Symmetry in QFT on Quantum Bianchi I Space-Time

    Full text link
    We develop the quantum theory of a scalar field on LQC Bianchi I geometry. In particular, we focus on single modes of the field: the evolution equation is derived from the quantum scalar constraint, and it is shown that the same equation can be obtained from QFT on an "classical" effective geometry. We investigate the dependence of this effective space-time on the wavevector of the mode (which could in principle generate a deformation in local Lorentz-symmetry), focusing our attention on the dispersion relation. We prove that when we disregard backreaction no Lorentz-violation is present, despite the effective metric being different than the classical Bianchi I one. A preliminary analysis of the correction due to inclusion of backreaction is briefly discussed in the context of Born-Oppenheimer approximation.Comment: 14 pages, v3. Corrected a reference in the bibliograph

    Grain growth competition during melt pool solidification -- Comparing phase-field and cellular automaton models

    Full text link
    A broad range of computational models have been proposed to predict microstructure development during solidification processing but they have seldom been compared to each other on a quantitative and systematic basis. In this paper, we compare phase-field (PF) and cellular automaton (CA) simulations of polycrystalline growth in a two-dimensional melt pool under conditions relevant to additive manufacturing (powder-bed fusion). We compare the resulting grain structures using local (point-by-point) measurements, as well as averaged grain orientation distributions over several simulations. We explore the effect of the CA spatial discretization level and that of the melt pool aspect ratio upon the selected grain texture. Our simulations show that detailed microscopic features related to transient growth conditions and solid-liquid interface stability (e.g. the initial planar growth stage prior to its cellular/dendritic destabilization, or the early elimination of unfavorably oriented grains due to neighbor grain sidebranching) can only be captured by PF simulations. The resulting disagreement between PF and CA predictions can only be addressed partially by a refinement of the CA grid. However, overall grain distributions averaged over the entire melt pools of several simulations seem to lead to a notably better agreement between PF and CA, with some variability with the melt pool shape and CA grid. While further research remains required, in particular to identify the appropriate selection of CA spatial discretization and its link to characteristic microstructural length scales, this research provides a useful step forward in this direction by comparing both methods quantitatively at process-relevant length and time scales

    Physiological and psychological correlates of fatigue in HIV/AIDS

    Get PDF
    Fatigue is a frequent symptom reported by persons living with HIV disease and one that affects all aspects of quality of life. To improve quality of care of persons with HIV disease, it is important to address all factors that contribute to fatigue. The purpose of this study was to determine the associations of physiological, psychological, and sociological factors with fatigue in an HIV-infected population. With Piper’s integrated fatigue model guiding selection, factors examined in this study were hemoglobin, hematocrit, CD4+ cell count, HIV-RNA viral load, total sleep time, sleep quality, daytime sleepiness, HIV-related symptoms, anxiety, depression, and perceived stress. The sample (N = 79) for this descriptive correlational study was recruited from a primary health care association in South Carolina and consisted of 42 (53.2%) HIV-infected women and 37 (46.8%) HIV-infected men between the ages of 24 and 63 years (x = 39.9, s = 7.9). Of the participants, 70 (90%) were African American, 5 (6%) were Caucasian, and 3 (4%) were Hispanic. Using Pearson’s r, significant relationships were observed between fatigue and sleep quality, daytime sleepiness, HIV-related symptoms, state anxiety, trait anxiety, depression, and perceived stress. Sleep quality (F5,65 = 12.02, P = 0.0009), state anxiety (F5,65 = 8.28, P = 0.0054), HIV-related symptoms (F5,65 = 4.87, P = 0.0308), and depression (F5,65 = 7.31, P = 0.0087) retained significance in a 3-step, backward stepwise elimination model and accounted for 67% of the variance in fatigue. These findings underscore the need for addressing psychosocial stressors and sleep quality in developing effective care for HIV-infected individuals who experience fatigue

    Health care provider\u27s influence on HIV-infected women\u27s belief and intentions related to AZT therapy

    Get PDF
    This study examined how women’s relationship with their primary health care provider (PHP) and their perceptions about how effective their PHPs believe zidovudine (AZT) to be in decreasing perinatal transmission related to women’s AZT beliefs and intentions. It used a cross-sectional design to collect data from 59 HIV-infected African American women. Almost half the women (45%) had given birth since HIV diagnosis. Most of the babies born to HIV-infected mothers (87%) were seronegative. Data analysis with Pearson’s r indicated that the quality of the women’s relationship with their PHP was positively correlated to how important the PHP would be in decision making related to AZT therapy. Significant positive correlation was observed between women’s perceptions about how effective their PHPs believed AZT to be in decreasing perinatal HIV transmission and the women’s own beliefs about AZT, their intent to take AZT if pregnant, and intent to give AZT to a newborn

    Preparation of Diltiazem Topical Gel for the Treatment of Anal Fissure and In-vitro, Ex-vivo Drug Release Evaluations

    Get PDF
    Abstract: Introduction: Anal fissures are small tears in the lining skin of the anus presenting with typical symptoms of pain and bleeding during defecation. Several new forms of medicines such as glyceryle trinitrate (GTN) ointments and diltiazem, a calcium channel-blocking agent, have been recently used for the treatment of these fissures. Diltiazem relaxes the muscle of anal sphincter and consequently increases blood flow to promote healing. It does not have GTN side effects like headache, anal burning and hypotension. The objective of this study was to formulate a suitable topical gel from diltiazem and then to investigate its physicochemical stability and also the drug release profiles from the bases. Methods: Various formulations of gel base including Guar 1.25%, Tragacanth 1.5%, HPMC 1%, and HPMC 1.5% were prepared and in vitro release and penetration characteristics of diltiazem from each preparation were studied through a hydrophilic dora pore diffusion barrier and membrane excised rat skin using Franz cell over a period of 5 hours. The amount of drug released from topical preparations was determined spectrophotometrically at ? max=236 nm. Stability studies and shelf life assessments were performed too. Results: Gel formulations containing HPMC, Guar and Tragacanth presented both good chemical and physical stabilities. The rates of cumulative drug release from HPMC 1%, HPMC 1.5%, Guar 1.25% and Tragacanth 1.5% bases using synthetic membrane were 89.7%, 76.7%, 94.9% and 66.1% respectively. For excised rat skin test, the cumulative percent of penetrated drug at the end of each experiment were 52.7 %, 50.9%, 64.6% and 42.6% for HPMC 1%, HPMC 1.5%, Guar 1.25% and Tragacanth 1.5% bases respectively. Conclusion: The comparative study showed that the percent of drug release from synthetic membrane was more than the percent of penetrated drug through excised rat skin for all bases (P<0.05). It was concluded that the kinetics of diltiazem release in vitro was not affected by the kind of gel forming agent and for all of the formulations, Higuchi’s kinetic model was suitable to explain their kinetics. Keywords: Diltiazem, Topical gel, Anal fissur

    A spatial modeling approach for linguistic object data : analysing dialect sound variations across Great Britain

    Get PDF
    Dialect variation is of considerable interest in linguistics and other social sciences. However, traditionally it has been studied using proxies (transcriptions) rather than acoustic recordings directly. We introduce novel statistical techniques to analyze geolocalized speech recordings and to explore the spatial variation of pronunciations continuously over the region of interest, as opposed to traditional isoglosses, which provide a discrete partition of the region. Data of this type require an explicit modeling of the variation in the mean and the covariance. Usual Euclidean metrics are not appropriate, and we therefore introduce the concept of d-covariance, which allows consistent estimation both in space and at individual locations. We then propose spatial smoothing for these objects which accounts for the possibly nonconvex geometry of the domain of interest. We apply the proposed method to data from the spoken part of the British National Corpus, deposited at the British Library, London, and we produce maps of the dialect variation over Great Britain. In addition, the methods allow for acoustic reconstruction across the domain of interest, allowing researchers to listen to the statistical analysis. Supplementary materials for this article are available online

    Rejoinder for “A spatial modeling approach for linguistic object data : analysing dialect sound variations across Great Britain”

    Get PDF
    "Rejoinder for “A Spatial Modeling Approach for Linguistic Object Data: Analyzing Dialect Sound Variations Across Great Britain”." Journal of the American Statistical Association, 114(527), pp. 1103–110
    • …
    corecore