2,545 research outputs found

    Remote sensing of coccolithophore blooms in selected oceanic regions using the PhytoDOAS method applied to hyper-spectral satellite data

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    In this study temporal variations of coccolithophore blooms are investigated using satellite data. Eight years (from 2003 to 2010) of data of SCIAMACHY, a hyper-spectral satellite sensor on-board ENVISAT, were processed by the PhytoDOAS method to monitor the biomass of coccolithophores in three selected regions. These regions are characterized by frequent occurrence of large coccolithophore blooms. The retrieval results, shown as monthly mean time series, were compared to related satellite products, including the total surface phytoplankton, i.e. total chlorophyll a (from GlobColour merged data) and the particulate inorganic carbon (from MODIS-Aqua). The inter-annual variations of the phytoplankton bloom cycles and their maximum monthly mean values have been compared in the three selected regions to the variations of the geophysical parameters: sea-surface temperature (SST), mixed-layer depth (MLD) and surface wind-speed, which are known to affect phytoplankton dynamics. For each region, the anomalies and linear trends of the monitored parameters over the period of this study have been computed. The patterns of total phytoplankton biomass and specific dynamics of coccolithophore chlorophyll a in the selected regions are discussed in relation to other studies. The PhytoDOAS results are consistent with the two other ocean color products and support the reported dependencies of coccolithophore biomass dynamics on the compared geophysical variables. This suggests that PhytoDOAS is a valid method for retrieving coccolithophore biomass and for monitoring its bloom developments in the global oceans. Future applications of time series studies using the PhytoDOAS data set are proposed, also using the new upcoming generations of hyper-spectral satellite sensors with improved spatial resolution

    Baryon Binding Energy in Sakai-Sugimoto Model

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    The binding energy of baryon has been studied in the dual AdS5×S5AdS_5\times S^5 string theory with a black hole interior. In this picture baryon is constructed of a D5D_5 brane vertex wrapping on S5S^5 and NcN_c fundamental strings connected to it. Here, we calculate the baryon binding energy in Sakai-Sugimoto model with a D4/D8/D8ˉD_4/D_8/\bar{D_8} in which the supersymmetry is completely broken. Also we check the TT dependence of the baryon binding energy. We believe that this model represents an accurate description of baryons due to the existence of Chern-Simones coupling with the gauge field on the brane. We obtain an analytical expression for the baryon binding energy . In that case we plot the baryon binding energy in terms of radial coordinate. Then by using the binding energy diagram, we determine the stability range for baryon configuration. And also the position and energy of the stable equilibrium point is obtained by the corresponding diagram. Also we plot the baryon binding energy in terms of temperature and estimate a critical temperature in which the baryon would be dissociated.Comment: 14 pages, 1 fi

    Urinary Albumin and Interleukin-8 Levels are not Good Indicators of Ongoing Vesicoureteral Reflux in Children who have no Active Urinary Tract Infection

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    Introduction: Vesicoureteral reflux (VUR) is a risk factor for kidney scarring, hypertension and declining renal function. Standard diagnostic methods are invasive and can cause exposure to radiation and urinary tract infections (UTIs). We aimed to investigate urine albumin and interleukin-8 levels as markers of ongoing VUR and renal damage in children without UTIs. Methods: Random urine samples were collected from 51 children, including 16 children with VUR (group A), 17 children with resolved VUR (group B) and 18 normal children (group C). The diagnosis of VUR or resolved VUR was confirmed by voiding cystourethrogram (VCUG) or direct radionuclide cystography (DRNC). All children had normal kidney function and had no evidence of UTI in the preceding three months. Random urine specimens were assayed for albumin (Alb), creatinine (Cr) and interleukin-8 (IL-8) and mean values were compared by one way ANOVA. Results: In groups A and B, the mean age at first UTI was 31.7 ± 2.4 and 27 ± 2.0 months respectively. In group A, the mean duration between VUR diagnosis and study entrance was 30 ± 9.1 months. In group B, the mean duration between VUR diagnosis and recovery was 19.9 ± 1.3 months. Overall, 76.4% of affected children had bilateral VUR and 41.2% had severe VUR. There were no significant differences in urinary Alb, IL-8, Alb/Cr and IL-8/Cr between the three groups. Conclusion: The current study does not support the hypothesis that microalbuminuria or urinary IL-8 are good indicators of ongoing VUR and renal injury in children. Keywords: Children; Interleukin-8; Microalbuminuria; Vesicoureteral Reflux

    Factors Affecting Minor Psychiatric Disorder in Southern Iranian Nurses: A Latent Class Regression Analysis

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    Background: Mental health is one of the most important dimensions of life and its quality. Minor Psychiatric Disorder as a type of mental health problem is prevalent among health workers. Nursing is considered to be one of the most stressful occupations. Objectives: This study aimed to evaluate the prevalence of minor psychiatric disorder and its associated factors among nurses in southern Iran. Patients and Methods: A cross-sectional study was carried out on 771 nurses working in 20 cities of Bushehr and Fars provinces in southern Iran. Participants were recruited through multi-stage sampling during 2014. The General Health Questionnaire (GHQ-12) was used for screening of minor psychiatric disorder in nurses. Latent Class Regression was used to analyze the data. Results: The prevalence of minor psychiatric disorder among nurses was estimated to be 27.5%. Gender and sleep disorders were significant factors in determining the level of minor psychiatric disorder (P Values of 0.04 and < 0.001, respectively). Female nurses were 20% more likely than males to be classified into the minor psychiatric disorder group. Conclusions: The results of this study provide information about the prevalence of minor psychiatric disorder among nurses, and factors, which affect the prevalence of such disorders. These findings can be used in strategic planning processes to improve nurses’ mental health

    Calculating the jet-quenching parameter in STU background

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    In this paper we use the AdS/CFT correspondence to compute the jet-quenching parameter in a N=2 thermal plasma. We consider the general three-charge black hole and discuss some special cases. We add a constant electric field to the background and find the effect of the electric field on the jet-quenching parameter. Also we include higher derivative terms and obtain the first-order correction for the jet-quenching parameter.Comment: 17 pages, 3 figures, revised versio

    Nanoscopic compartmentalization of membrane protein motion at the axon initial segment

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    The axon initial segment (AIS) is enriched in specific adaptor, cytoskeletal, and transmembrane molecules. During AIS establishment, a membrane diffusion barrier is formed between the axonal and somatodendritic domains. Recently, an axonal periodic pattern of actin, spectrin, and ankyrin forming 190-nm-spaced, ring-like structures has been discovered. However, whether this structure is related to the diffusion barrier function is unclear. Here, we performed single-particle tracking time-course experiments on hippocampal neurons during AIS development. We analyzed the mobility of lipid-anchored molecules by high-speed single-particle tracking and correlated positions of membrane molecules with the nanoscopic organization of the AIS cytoskeleton. We observe a strong reduction in mobility early in AIS development. Membrane protein motion in the AIS plasma membrane is confined to a repetitive pattern of ∼190-nm-spaced segments along the AIS axis as early as day in vitro 4, and this pattern alternates with actin rings. Mathematical modeling shows that diffusion barriers between the segments significantly reduce lateral diffusion along the axon

    Breast-Lesion Characterization using Textural Features of Quantitative Ultrasound Parametric Maps

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    © 2017 The Author(s). This study evaluated, for the first time, the efficacy of quantitative ultrasound (QUS) spectral parametric maps in conjunction with texture-analysis techniques to differentiate non-invasively benign versus malignant breast lesions. Ultrasound B-mode images and radiofrequency data were acquired from 78 patients with suspicious breast lesions. QUS spectral-analysis techniques were performed on radiofrequency data to generate parametric maps of mid-band fit, spectral slope, spectral intercept, spacing among scatterers, average scatterer diameter, and average acoustic concentration. Texture-analysis techniques were applied to determine imaging biomarkers consisting of mean, contrast, correlation, energy and homogeneity features of parametric maps. These biomarkers were utilized to classify benign versus malignant lesions with leave-one-patient-out cross-validation. Results were compared to histopathology findings from biopsy specimens and radiology reports on MR images to evaluate the accuracy of technique. Among the biomarkers investigated, one mean-value parameter and 14 textural features demonstrated statistically significant differences (p < 0.05) between the two lesion types. A hybrid biomarker developed using a stepwise feature selection method could classify the legions with a sensitivity of 96%, a specificity of 84%, and an AUC of 0.97. Findings from this study pave the way towards adapting novel QUS-based frameworks for breast cancer screening and rapid diagnosis in clinic

    On the formation and decay of a molecular ultracold plasma

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    Double-resonant photoexcitation of nitric oxide in a molecular beam creates a dense ensemble of 50f(2)50f(2) Rydberg states, which evolves to form a plasma of free electrons trapped in the potential well of an NO+^+ spacecharge. The plasma travels at the velocity of the molecular beam, and, on passing through a grounded grid, yields an electron time-of-flight signal that gauges the plasma size and quantity of trapped electrons. This plasma expands at a rate that fits with an electron temperature as low as 5 K, colder that typically observed for atomic ultracold plasmas. The recombination of molecular NO+^+ cations with electrons forms neutral molecules excited by more than twice the energy of the NO chemical bond, and the question arises whether neutral fragmentation plays a role in shaping the redistribution of energy and particle density that directs the short-time evolution from Rydberg gas to plasma. To explore this question, we adapt a coupled rate-equations model established for atomic ultracold plasmas to describe the energy-grained avalanche of electron-Rydberg and electron-ion collisions in our system. Adding channels of Rydberg predissociation and two-body, electron- cation dissociative recombination to the atomic formalism, we investigate the kinetics by which this relaxation distributes particle density and energy over Rydberg states, free electrons and neutral fragments. The results of this investigation suggest some mechanisms by which molecular fragmentation channels can affect the state of the plasma

    AdS5AdS_{5} black hole at N=2 supergravity

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    In this paper, we consider the charged non-extremal black hole at five dimensional N = 2 supergravity. We study thermodynamics of AdS_{5} black hole with three equal charges (q_{1} = q_{2} = q_{3} = q). We obtain Schrodinger like equation and discuss the effective potential. Then, we consider the case of the perturbed dilaton field background and find presence of odd coefficients of the wave function. Also we find that the higher derivative corrections have no effect on the first and second even coefficients of the wave function.Comment: 17 pages, 4 figures. Published versio
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