5,856 research outputs found

    Essential fish habitats (EFH) of small pelagic fishes in the north of the Persian Gulf and Oman Sea, Iran

    Get PDF
    Small pelagic fishes particularly anchovy (Encrasicholina punctifer) and sardine (Sardinella sindensis) have an important role to support the Iranian fisheries and are distributed along the coastal waters of the Persian Gulf and Oman Sea. Using a logbook on small pelagic fisheries, a GIS-based environmental modeling approach was applied to investigate the presence and abundance of anchovy and sardine in relation to environmental variables. Redundancy analysis (RDA) was applied to provide a preliminary view of the relationships between fish presence/absence and environmental variables. Generalized Additive Models (GAMs) indicated the presence/absence of fish was related to distance from the nearest coast, depth, sea surface Chlorophyll-a, and SST. Results of the EFH showed that sardine is concentrated in specific areas of more favorable conditions, such as north of the Persian Gulf and all areas of the northwest of the Oman Sea. However, EFH of anchovy showed a more widespread distribution, occupying most of the north-west of the Oman Sea coastal waters, south of Qeshm Island in the Strait of Hormoz as well as the Parsian district in the north of the Persian Gulf. In this study, it seems that the anchovy showed the probability of presence in the areas with more distance from the coastal waters. However, the EFH probability presences of sardine were predicted for near coastal water and obviously, shallower waters. Due to the development of small pelagic fisheries, it is highly recommended to investigate anchovy and sardine fishing possibility in areas with high EFH prediction probability

    Dynamic of a non homogeneously coarse grained system

    Full text link
    To study materials phenomena simultaneously at various length scales, descriptions in which matter can be coarse grained to arbitrary levels, are necessary. Attempts to do this in the static regime (i.e. zero temperature) have already been developed. In this letter, we present an approach that leads to a dynamics for such coarse-grained models. This allows us to obtain temperature-dependent and transport properties. Renormalization group theory is used to create new local potentials model between nodes, within the approximation of local thermodynamical equilibrium. Assuming that these potentials give an averaged description of node dynamics, we calculate thermal and mechanical properties. If this method can be sufficiently generalized it may form the basis of a Molecular Dynamics method with time and spatial coarse-graining.Comment: 4 pages, 4 figure

    TeV Scale Implications of Non Commutative Space time in Laboratory Frame with Polarized Beams

    Full text link
    We analyze e+eγγe^{+}e^{-}\rightarrow \gamma\gamma, eγeγe^{-}\gamma \rightarrow e^{-}\gamma and γγe+e\gamma\gamma \rightarrow e^{+}e^{-} processes within the Seiberg-Witten expanded noncommutative scenario using polarized beams. With unpolarized beams the leading order effects of non commutativity starts from second order in non commutative(NC) parameter i.e. O(Θ2)O(\Theta^2), while with polarized beams these corrections appear at first order (O(Θ)O(\Theta)) in cross section. The corrections in Compton case can probe the magnetic component(ΘB\vec{\Theta}_B) while in Pair production and Pair annihilation probe the electric component(ΘE\vec{\Theta}_E) of NC parameter. We include the effects of earth rotation in our analysis. This study is done by investigating the effects of non commutativity on different time averaged cross section observables. The results which also depends on the position of the collider, can provide clear and distinct signatures of the model testable at the International Linear Collider(ILC).Comment: 22 pages, 19 figures, new comments and references added, few typos corrected, Published in JHE

    http://www.agrimet.ir/article_69418_f4e2bbe100cda91f8c910d33a104a621.pdf

    Get PDF
    Incomplete rainfall datasets with missing gaps is a major challenge in climatology and water resource studies. In the present study, two intelligent models, namely Genetic Programing (GP) and Support Vector Machines (SVM) were used to reconstruct the monthly rainfall data of four rain-gauges located in Hamedan province, Iran during the period of 1992 to 2011. The incomplete rainfall data was reconstructed first by using the data of one, two and three stations respectively. The results showed that increasing the memory and the number of stations involved in the training phase, will improve the performance of the models. In reconstruction of monthly precipitation data of Sarabi and Maryanj stations, the Support Vector Machine method showed better performance with RMSE of 12.9 mm and 11.4 mm, and correlation coefficients (r) of 0.93 and 0.95, respectively. The corresponding values of RMSE for GP approach were 13 mm and 12.21 mm, which indicated the superior performance of SVM

    Neutrino-electron scattering in noncommutative space

    Full text link
    Neutral particles can couple with the U(1)U(1) gauge field in the adjoint representation at the tree level if the space-time coordinates are noncommutative (NC). Considering neutrino-photon coupling in the NC QED framework, we obtain the differential cross section of neutrino-electron scattering. Similar to the magnetic moment effect, one of the NC terms is proportional to 1T\frac 1 T, where TT is the electron recoil energy. Therefore, this scattering provides a chance to achieve a stringent bound on the NC scale in low energy by improving the sensitivity to the smaller electron recoil energy.Comment: 12 pages, 2 figure

    Time-Space Noncommutativity in Gravitational Quantum Well scenario

    Get PDF
    A novel approach to the analysis of the gravitational well problem from a second quantised description has been discussed. The second quantised formalism enables us to study the effect of time space noncommutativity in the gravitational well scenario which is hitherto unavailable in the literature. The corresponding first quantized theory reveals a leading order perturbation term of noncommutative origin. Latest experimental findings are used to estimate an upper bound on the time--space noncommutative parameter. Our results are found to be consistent with the order of magnitude estimations of other NC parameters reported earlier.Comment: 7 pages, revTe

    The Effect of Lattice Vibrations on Substitutional Alloy Thermodynamics

    Get PDF
    A longstanding limitation of first-principles calculations of substitutional alloy phase diagrams is the difficulty to account for lattice vibrations. A survey of the theoretical and experimental literature seeking to quantify the impact of lattice vibrations on phase stability indicates that this effect can be substantial. Typical vibrational entropy differences between phases are of the order of 0.1 to 0.2 k_B/atom, which is comparable to the typical values of configurational entropy differences in binary alloys (at most 0.693 k_B/atom). This paper describes the basic formalism underlying ab initio phase diagram calculations, along with the generalization required to account for lattice vibrations. We overview the various techniques allowing the theoretical calculation and the experimental determination of phonon dispersion curves and related thermodynamic quantities, such as vibrational entropy or free energy. A clear picture of the origin of vibrational entropy differences between phases in an alloy system is presented that goes beyond the traditional bond counting and volume change arguments. Vibrational entropy change can be attributed to the changes in chemical bond stiffness associated with the changes in bond length that take place during a phase transformation. This so-called ``bond stiffness vs. bond length'' interpretation both summarizes the key phenomenon driving vibrational entropy changes and provides a practical tool to model them.Comment: Submitted to Reviews of Modern Physics 44 pages, 6 figure

    Long-term disease burden and survivorship issues after surgery and radiotherapy of intracranial meningioma patients

    Get PDF
    BACKGROUND Many intracranial meningioma patients have an impaired health-related quality of life (HRQoL) and neurocognitive functioning up to 4 yr after intervention. OBJECTIVE To assess the long-term (≥5 yr) disease burden of meningioma patients. METHODS In this multicenter cross-sectional study, patients ≥5 yr after intervention (including active magnetic resonance imaging (MRI) surveillance) were included and assessed for HRQoL (Short-Form Health Survey 36), neurocognitive functioning (neuropsychological assessment), anxiety and depression (Hospital Anxiety and Depression Scale), and work productivity (Short Form-Health and Labour Questionnaire). Multivariable and propensity score regression analyses were used to compare patients and controls, and different treatment strategies corrected for possible confounders. Clinically relevant differences were reported. RESULTS At a median of 9 yr follow-up after intervention, meningioma patients (n = 190) reported more limitations due to physical (difference 12.5 points, P = .008) and emotional (13.3 points, P = .002) health problems compared with controls. Patients also had an increased risk to suffer from anxiety (odds ratio [OR]: 2.6, 95% CI: 1.2-5.7) and depression (OR: 3.7, 95% CI: 1.3-10.5). Neurocognitive deficits were found in 43% of patients. Although postoperative complications, radiotherapy, and reresection were associated with worse verbal memory, attention, and executive functioning when compared to patients resected once, the only clinically relevant association was between reresection and worse attention (–2.11, 95% CI: –3.52 to –0.07). Patients of working age less often had a paid job (48%) compared with the working-age Dutch population (72%) and reported more obstacles at work compared with controls. CONCLUSION In the long term, a large proportion of meningioma patients have impaired HRQoL, neurocognitive deficits, and high levels of anxiety or depression. Patients treated with 1 resection have the best neurocognitive functioning
    corecore