4,530 research outputs found

    Temporal and spatial distribution of phytoplankton with emphasis on Skeletonema costatum in the Mathamuhuri river – estuary (Chakaria mangrove ecosystem), Bangladesh

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    A total of 91 species under 44 genera were identified among the phytoplankton community during the course of one year's investigation between May 1982 and April 1983. Bacillariophyta was the most dominant group with 72 specie, Chlorophyta 11 spp, Cyanophyta 6 spp and Pyrrophyta was represented by 2 species. The yearly percentage composition of 4 groups of phytoplankton in order of abundance were Bacillariophyta 50.77%, Cyanophyta 47.70%, Chlorophyta 1.5% and Pyrrophyta 0.02%. The highest densities of phytoplankton were recorded in monsoon months (June-July) with a peak in July (31550 cells/l) and the minimum in February (770 cells/1). Higher concentration of phytoplankton was recorded at station 2, nearer to the Chakaria Sundarbans (mangroves), but abundance of phytoplankton showed no significant difference in the two stations (Mann Whitney U test, P=0.64, Z=-0.642, U=64). Phytoplankton population in this area were positively correlated with rainfall (r=0.655, P=<0.5, df.22) and water temperature (r=0.523, P=<0.05). Skeletonema costatum was the dominant member of phytoplankton and occupied 35.23% of the annual population and occurred throughout the period of study except in September and January. Its abundance was recorded during the monsoon months (April- July) with a maximum density (24185 cells/l) in July. No significant correlation was found between abundance of S. costatum and the hydro-meteorological parameters recorded in the Chakaria mangrove area

    Spin exchange dominated by charge fluctuations of the Wigner lattice in the newly synthesized chain cuprate Na5Cu3O6

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    Na5Cu3O6, a new member of one dimensional charge ordered chain cuprates, was synthesized via the azide/nitrate route by reacting NaN3, NaNO3 and CuO. According to single crystal X-ray analysis, one dimensional CuO2 chains built up from planar, edge-sharing CuO4 squares are a dominant feature of the crystal structure. From the analysis of the Cu-O bond lengths we find that the system forms a Wigner lattice. The commensurate charge order allows to explicitly assign the valence states of either +2 or +3 to each copper atom resulting in a repetition according to Cu(2+)-Cu(3+)-Cu(2+)-Cu(2+)-Cu(3+)-Cu(2+). Following the theoretical analysis of the previously synthesized compounds Na3Cu2O4 and Na8Cu5O10, the magnetic susceptibility was expected to show a large dimer gap. Surprisingly, this is not the case. To resolve this puzzle, we show that the magnetic couplings in this compound are strongly affected by excitations across the Wigner charge gap. By including these contributions, which are distinct from conventional superexchange in Mott-insulators, we obtain a quantitative satisfying theoretical description of the magnetic susceptibility data.Comment: 31 pages, 3 tables, 10 figure

    Massive, Absorption-selected Galaxies at Intermediate Redshifts

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    The nature of absorption-selected galaxies and their connection to the general galaxy population have been open issues for more than three decades, with little information available on their gas properties. Here we show, using detections of carbon monoxide (CO) emission with the Atacama Large Millimeter/submillimeter Array (ALMA), that five of seven high-metallicity, absorption-selected galaxies at intermediate redshifts, z0.50.8z \approx 0.5-0.8, have large molecular gas masses, MMol(0.68.2)×1010MM_{\rm Mol} \approx (0.6 - 8.2) \times 10^{10} \: {\rm M}_\odot and high molecular gas fractions (fMolMMol/(M+MMol)0.290.87)f_{\rm Mol} \equiv \: M_{\rm Mol}/(M_\ast + M_{\rm Mol}) \approx 0.29-0.87). Their modest star formation rates (SFRs), (0.39.5)M\approx (0.3-9.5) \: {\rm M}_\odot yr1^{-1}, then imply long gas depletion timescales, (3120)\approx (3 - 120) Gyr. The high-metallicity absorption-selected galaxies at z0.50.8z \approx 0.5-0.8 appear distinct from populations of star-forming galaxies at both z1.32.5z \approx 1.3-2.5, during the peak of star formation activity in the Universe, and lower redshifts, z0.05z \lesssim 0.05. Their relatively low SFRs, despite the large molecular gas reservoirs, may indicate a transition in the nature of star formation at intermediate redshifts, z0.7z \approx 0.7.Comment: 8 pages, 3 figures; accepted for publication in Astrophysical Journal Letters. Minor changes to match the version in press in ApJ

    Risk factors for cardiovascular disease in school children--a pilot study.

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    OBJECTIVE: To assess the frequencies of risk factors for cardiovascular disease in school children. The information may help in designing interventions aimed at modifying unhealthy lifestyle in children, which may reduce the later incidence of cardiovascular disease in adults. METHODS: A cross-sectional study was conducted on 206 students (ages 14-18 years), enrolled in higher secondary school. Students were interviewed about their lifestyles, family history of cardiovascular disease and its risk factors. Moreover, they were assessed for height, weight and blood pressure. RESULTS: Twenty nine percent of the children were physically inactive, 31% were taking unhealthy diet daily, 21% were overweight (BMI \u3e or = 25) and 6% were smokers. History of paternal smoking was reported by 36% of the children, and among them 76% of fathers smoked in the presence of their children. Family history of cardiac disease, hypertension and diabetes were positive in 4%, 23% and 16% of the children respectively. Overall, 58% of the children had at least one modifiable risk factor. CONCLUSION: Majority of the children had modifiable risk factors for cardiovascular disease. Prevention efforts are required early in life, using strategies for behavioral modification and health promotion

    Improved Core Genes Prediction for Constructing well-supported Phylogenetic Trees in large sets of Plant Species

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    The way to infer well-supported phylogenetic trees that precisely reflect the evolutionary process is a challenging task that completely depends on the way the related core genes have been found. In previous computational biology studies, many similarity based algorithms, mainly dependent on calculating sequence alignment matrices, have been proposed to find them. In these kinds of approaches, a significantly high similarity score between two coding sequences extracted from a given annotation tool means that one has the same genes. In a previous work article, we presented a quality test approach (QTA) that improves the core genes quality by combining two annotation tools (namely NCBI, a partially human-curated database, and DOGMA, an efficient annotation algorithm for chloroplasts). This method takes the advantages from both sequence similarity and gene features to guarantee that the core genome contains correct and well-clustered coding sequences (\emph{i.e.}, genes). We then show in this article how useful are such well-defined core genes for biomolecular phylogenetic reconstructions, by investigating various subsets of core genes at various family or genus levels, leading to subtrees with strong bootstraps that are finally merged in a well-supported supertree.Comment: 12 pages, 7 figures, IWBBIO 2015 (3rd International Work-Conference on Bioinformatics and Biomedical Engineering

    PREVALENCE AND ANTHELMINTIC EFFICACY OF ABAMECTIN AGAINST GASTROINTESTINAL PARASITES IN HORSES

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    The prevalence and anthelmintic efficacy of Abamectin against gastrointestinal parasites under field conditions in Faisalabad (Punjab, Pakistan) was studied in 100 horses. The overall prevalence of gastrointestinal parasites was 75%, including Strongylus spp. (50%), Oxyuris equi (12%), Parascaris equorum (8%) and mixed infection (5%). Among these naturally infected animals, 15 were selected. These horses were assigned to three groups on the basis of prevalent species of gastrointestinal parasites. Each group had five animals, comprising four treatment horses and a control horse. Abamectin was evaluated against these gastrointestinal parasites with a single shot at the dose rate of 0.2 mg/kg body weight administered through subcutaneous route which resulted in 98% reduction in faecal egg count after day 14 post-treatment. Non-treated horses remained positive for gastrointestinal parasites. No adverse reactions were observed during the experimental period. It was concluded that Abamectin is highly effective against gastrointestinal parasites in horses

    Detection of Inositol Polyphosphates by Polyacrylamide Gel Electrophoresis (PAGE) under Apoptotic Conditions in Cultured SW480 Cells

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    Inositol phosphates are naturally occurring compounds that regulate diverse cellular processes including apoptosis. Apoptosis is a mechanism by which cells undergo natural death to maintain cellular homeostasis. It causes cell death in areas during a state that is harmful to the body. It also regulates cellular development. Previous work has shown that exogenously administered, as well as endogenously manipulated inositol phosphates bring about apoptotic changes. It has been demonstrated that cellular levels of inositol phosphates, particularly higher inositol phosphates such as inositol hexakis-phosphate (IP6) and diphosphoinositol pentakis-phosphate (IP7) levels increase during apoptotic conditions. In this study, we have attempted to separate and identify higher inositol phosphates such as IP6 by polyacrylamide gel electrophoresis (PAGE) and shown that changes in inositol phosphate levels can be detected by this method. Cells were treated with etoposide to induce apoptosis, and apoptotic cells were observed under UV light following ethidium bromide/acridine orange staining. This staining showed that IP3 - IP6 induced apoptosis in SW480 cells with IP6 being the most effective inducing agent. The extracts from apoptotic and control cells were then loaded onto the polyacrylamide gel and run along with standard IP6. Results showed that IP6 could be detected using the PAGE method and that cellular levels of IP6 were increased in SW480 cells, in which apoptosis had been induced by etoposide. Our results demonstrated that this technique could be utilized instead of the laborious radioactive labeling and HPLC separation method to study the changes in cellular levels of inositol phosphates particularly IP6

    The Achievable Rate of Interweave Cognitive Radio in the Face of Sensing Errors

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    Cognitive radio (CR) systems are potentially capable of mitigating the spectrum shortage of contemporary wireless systems. In this paper, we provide a brief overview of CR systems and the important research milestones of their evolution, along with their standardization activities, as a result of their research. This is followed by the detailed analysis of the interweave policy-based CR network (CRN) and by a detailed comparison with the family of underlay-based CRNs. In the interweave-based CRN, sensing of the primary user's (PU) spectrum by the secondary user's (SU) has remained a challenge, because the sensing errors prevent us from fulfilling the significant throughput gains that the concept of CR promises. Since missed detection and false alarm errors in real-time spectrum sensing cannot be avoided, based on a new approach, we quantify the achievable rates of the interweave CR by explicitly incorporating the effect of sensing errors. The link between the PU transmitter and the SU transmitter is assumed to be fast fading. Explicitly, the achievable rate degradation imposed by the sensing errors is analyzed for two spectrum sensing techniques, namely, for energy detection and for magnitude squared coherence-based detection. It is demonstrated that when the channel is sparsely occupied by the PU, the reusing techniques that are capable of simultaneously providing low missed detection and false alarm probabilities cause only a minor degradation to the achievable rates. Furthermore, based on the achievable rates derived for underlay CRNs, we compare the interweave CR and the underlay CR paradigms from the perspective of their resilience against spectrum sensing errors. Interestingly, in many practical regimes, the interweave CR paradigm outperforms the underlay CR paradigm in the presence of sensing errors, especially when the SNR at the SU is below 10 dB and when the SNR at the PU is in the range of 10-40 dB. Furthermore, we also provide rules of thumb that identify regimes, where the interweave CR outperforms the underlay CR

    The SAMI Galaxy Survey: the intrinsic shape of kinematically selected galaxies

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    Using the stellar kinematic maps and ancillary imaging data from the Sydney AAO Multi Integral field (SAMI) Galaxy Survey, the intrinsic shape of kinematically-selected samples of galaxies is inferred. We implement an efficient and optimised algorithm to fit the intrinsic shape of galaxies using an established method to simultaneously invert the distributions of apparent ellipticities and kinematic misalignments. The algorithm output compares favourably with previous studies of the intrinsic shape of galaxies based on imaging alone and our re-analysis of the ATLAS3D data. Our results indicate that most galaxies are oblate axisymmetric. We show empirically that the intrinsic shape of galaxies varies as a function of their rotational support as measured by the "spin" parameter proxy Lambda_Re. In particular, low spin systems have a higher occurrence of triaxiality, while high spin systems are more intrinsically flattened and axisymmetric. The intrinsic shape of galaxies is linked to their formation and merger histories. Galaxies with high spin values have intrinsic shapes consistent with dissipational minor mergers, while the intrinsic shape of low-spin systems is consistent with dissipationless multi-merger assembly histories. This range in assembly histories inferred from intrinsic shapes is broadly consistent with expectations from cosmological simulations.Comment: 15 pages, 11 figures, MNRAS in prin

    The Suaineadh Project : a stepping stone towards the deployment of large flexible structures in space

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    The Suaineadh project aims at testing the controlled deployment and stabilization of space web. The deployment system is based on a simple yet ingenious control of the centrifugal force that will pull each of the four daughters sections apart. The four daughters are attached onto the four corners of a square web, and will be released from their initial stowed configuration attached to a central hub. Enclosed in the central hub is a specifically designed spinning reaction wheel that controls the rotational speed with a closed loop control fed by measurements from an onboard inertial measurement sensor. Five other such sensors located within the web and central hub provide information on the surface curvature of the web, and progression of the deployment. Suaineadh is currently at an advanced stage of development: all the components are manufactured with the subsystems integrated and are presently awaiting full integration and testing. This paper will present the current status of the Suaineadh project and the results of the most recent set of tests. In particular, the paper will cover the overall mechanical design of the system, the electrical and sensor assemblies, the communication and power systems and the spinning wheel with its control system
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