1,729 research outputs found

    Crop-based irrigation operations in the North West Frontier Province of Pakistan. Vol.II: Research approach and interpretation. Final Report

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    Irrigation management / Crop-based irrigation / Research / Irrigation canals / Water demand / Performance evaluation / Agricultural production / Pakistan / North West Frontier Province

    Enhanced mechanical properties of a novel compatibilized recycled polyethylene terephthalate/polyamide 11 (rPET/PA11) blends

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    This research investigates various proportions of a compatibilizer, Joncryl®, in a newly developed blend of rPET/PA11 having 80 wt% rPET and 20 wt% PA11. The proposed blend exhibits unique and outstanding mechanical properties. A few of the significant benefits of carrying out this research work include recycling the highest amount of rPET, saving natural recourses, and encountering the environmental issues associated with the wastage of polymers. Five different proportions of Joncryl® (0, 1, 2, 3 and 4 phr) were introduced to the blend of rPET/PA11 through a twin-screw extruder and injection moulding machine. The blend interface studied by scanning electron microscope (SEM) indicated that Joncryl® boosted the chain extension. The results of tensile strength, Young’s modulus and flexural strength displayed the boost up in properties at all proportions; however, the properties at 2 phr of Joncryl® were unique and exclusive. The tensile strength of blend at 2 phr (Joncryl®) is remarkably increased from 26.8 to 46.24 MPa with a uniquely increased strain% from 3.56 to 196%. Young’s modulus is also significantly improved. The impact strength rose from 147.12 to 667.68 J/m

    Design and analysis of a photonic crystal based planar antenna for thz applications

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    Modern advancements in wearable smart devices and ultra-high-speed terahertz (THz) communication systems require low cost, low profile, and highly efficient antenna design with high directionality to address the propagation loss at the THz range. For this purpose, a novel shape, high gain antenna for THz frequency range applications is presented in this work. The proposed antenna is based on a photonic bandgap (PBG)-based crystal polyimide substrate which gives optimum performance in terms of gain (9.45 dB), directivity (9.99 dBi), and highly satisfactory VSWR (<1) at 0.63 THz. The performance of the antenna is studied on PBGs of different geometrical configurations and the results are compared with the antenna based on the homogeneous polyimide-based substrate. The effects of variations in the dimensions of the PBG unit cells are also studied to achieve a -10 dB bandwidth of 28.97 GHz (0.616 to 0.64 THz)

    A multicenter case control study of association of vitamin D with breast cancer among women in Karachi, Pakistan

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    BACKGROUND:The prevalence of vitamin D inadequacy and breast cancer are both high among women living in Karachi, Pakistan. METHODS:A matched case control study was conducted in two hospitals of Karachi, Pakistan to evaluate the association of vitamin D (serum 25-hydroxyvitamin D) concentrations, vitamin D supplementation and sun exposure with breast cancer among Pakistani women. A total of 411 newly diagnosed histologically confirmed primary breast cancer cases were enrolled and 784 controls, free of breast and any other cancers, were matched by age (year of birth Âą 5 years), residence in the same geographic area and study site. Information was collected on sociodemographic history, history of vitamin D supplementation, past medical and obstetrical history, family history of breast cancer, sun exposure history, histopathology reports and anthropometric measurement and venous blood was collected to measure serum 25-hydroxyvitamin D (25(OH)D) concentration. RESULTS:Compared to patients with sufficient serum vitamin D (>30 ng/ml), women with serum vitamin D deficiency (<20ng/ml), had a higher risk of breast cancer (OR = 1.65, 95%CI: 1.10, 2.50). Women with history of vitamin D supplementation one year prior to enrollment, had significant protective effect against breast cancer (OR = 0.32, 95% CI: 0.24, 0.43). CONCLUSIONS AND RECOMMENDATION:Serum vitamin D deficiency was associated with increased risk of breast cancer, while vitamin D supplementation was associated with decreased risk of breast cancer. In Pakistani women, where vitamin D deficiency is common, raising and maintaining serum vitamin D at population level is a safe and affordable strategy. It may play a role in reducing the incidence of both vitamin D deficiency and breast cancer, particularly among poor women where the breast cancer mortality is highest due to limited resources for early detection, diagnosis, and treatment. The effects of vitamin D with regard to breast cancer risk in Karachi Pakistan should be further evaluated.Uzma Shamsi, Shaista Khan, Iqbal Azam, Aysha Habib Khan ... Tiffany Gill ... David Callen ... et al

    Solid-state flurbiprofen and methyl-β-cyclodextrin inclusion complexes prepared using a single-step, organic solvent-free supercritical fluid process

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    The aim of this study was to enhance the apparent solubility and dissolution properties of flurbiprofen through inclusion complexation with cyclodextrins. Especially, the efficacy of supercritical fluid technology as a preparative technique for the preparation of flurbiprofen-methyl–β–cyclodextrin inclusion complexes was evaluated. The complexes were prepared by supercritical carbon dioxide processing and were evaluated by solubility, differential scanning calorimetry, X-ray powder diffraction, scanning electron microscopy, practical yield, drug content estimation and in vitro dissolution studies. Computational molecular docking studies were conducted to study the possibility of molecular arrangement of inclusion complexes between flurbiprofen and methyl-β-cyclodextrin. The studies support the formation of stable molecular inclusion complexes between the drug and cyclodextrin in a 1:1 stoichiometry. In vitro dissolution studies showed that the dissolution properties of flurbiprofen were significantly enhanced by the binary mixtures prepared by supercritical carbon dioxide processing. The amount of flurbiprofen dissolved into solution alone was very low with 1.11 ± 0.09% dissolving at the end of 60 min, while the binary mixtures processed by supercritical carbon dioxide at 45 °C and 200 bar released 99.39 ± 2.34% of the drug at the end of 30 min. All the binary mixtures processed by supercritical carbon dioxide at 45 °C exhibited a drug release of more than 80% within the first 10 min irrespective of the pressure employed. The study demonstrated the single step, organic solvent-free supercritical carbon dioxide process as a promising approach for the preparation of inclusion complexes between flurbiprofen and methyl–β–cyclodextrin in solid-state

    Compressed representation of a partially defined integer function over multiple arguments

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    In OLAP (OnLine Analitical Processing) data are analysed in an n-dimensional cube. The cube may be represented as a partially defined function over n arguments. Considering that often the function is not defined everywhere, we ask: is there a known way of representing the function or the points in which it is defined, in a more compact manner than the trivial one

    Azimuthal anisotropy of charged particles at high transverse momenta in PbPb collisions at sqrt(s[NN]) = 2.76 TeV

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    The azimuthal anisotropy of charged particles in PbPb collisions at nucleon-nucleon center-of-mass energy of 2.76 TeV is measured with the CMS detector at the LHC over an extended transverse momentum (pt) range up to approximately 60 GeV. The data cover both the low-pt region associated with hydrodynamic flow phenomena and the high-pt region where the anisotropies may reflect the path-length dependence of parton energy loss in the created medium. The anisotropy parameter (v2) of the particles is extracted by correlating charged tracks with respect to the event-plane reconstructed by using the energy deposited in forward-angle calorimeters. For the six bins of collision centrality studied, spanning the range of 0-60% most-central events, the observed v2 values are found to first increase with pt, reaching a maximum around pt = 3 GeV, and then to gradually decrease to almost zero, with the decline persisting up to at least pt = 40 GeV over the full centrality range measured.Comment: Replaced with published version. Added journal reference and DO

    Search for anomalous t t-bar production in the highly-boosted all-hadronic final state

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    A search is presented for a massive particle, generically referred to as a Z', decaying into a t t-bar pair. The search focuses on Z' resonances that are sufficiently massive to produce highly Lorentz-boosted top quarks, which yield collimated decay products that are partially or fully merged into single jets. The analysis uses new methods to analyze jet substructure, providing suppression of the non-top multijet backgrounds. The analysis is based on a data sample of proton-proton collisions at a center-of-mass energy of 7 TeV, corresponding to an integrated luminosity of 5 inverse femtobarns. Upper limits in the range of 1 pb are set on the product of the production cross section and branching fraction for a topcolor Z' modeled for several widths, as well as for a Randall--Sundrum Kaluza--Klein gluon. In addition, the results constrain any enhancement in t t-bar production beyond expectations of the standard model for t t-bar invariant masses larger than 1 TeV.Comment: Submitted to the Journal of High Energy Physics; this version includes a minor typo correction that will be submitted as an erratu

    Combined search for the quarks of a sequential fourth generation

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    Results are presented from a search for a fourth generation of quarks produced singly or in pairs in a data set corresponding to an integrated luminosity of 5 inverse femtobarns recorded by the CMS experiment at the LHC in 2011. A novel strategy has been developed for a combined search for quarks of the up and down type in decay channels with at least one isolated muon or electron. Limits on the mass of the fourth-generation quarks and the relevant Cabibbo-Kobayashi-Maskawa matrix elements are derived in the context of a simple extension of the standard model with a sequential fourth generation of fermions. The existence of mass-degenerate fourth-generation quarks with masses below 685 GeV is excluded at 95% confidence level for minimal off-diagonal mixing between the third- and the fourth-generation quarks. With a mass difference of 25 GeV between the quark masses, the obtained limit on the masses of the fourth-generation quarks shifts by about +/- 20 GeV. These results significantly reduce the allowed parameter space for a fourth generation of fermions.Comment: Replaced with published version. Added journal reference and DO
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