1,316 research outputs found

    Assessment of Nutrients Levels in Groundwater within the Lower Pra Basin of Ghana

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    The level of concentration of nitrates, phosphates, and sulphates was determined in groundwater within the Pra Basin to ascertain the degree of anthropogenic influence via the application of fertilizer and other agro-chemical to farmlands by farmers. Sixty-five (65) boreholes in forty-five (45) communities were analysed between January and April 2012 to cover the dry season and between June and October 2012 to cover the wet season. The results show that nitrate for both seasons range between 0.011 mg/l and 5.01 mg/l and therefore within the WHO (2006) guideline value of 10 mg/l, whilst that of phosphate range between 0.01 mg/l and 3.08 mg/l and therefore outside the USEPA guideline value of 2.5 mg/l. Sulphate recorded a range between 1.60 and 96.2 mg/l and therefore within the WHO (2006) guideline value of 250 mg/l. The concentration levels of the two nutrients of the parameters, nitrates and phosphate were correlated against borehole depth and the results show a weak positive and negative correlation for nitrate and phosphate respectively. There was thus, an indication that the levels of all parameters, nitrate, phosphate and sulphate are not yet a threat to groundwater in the basin

    Job performance expectations and perceptions of retail employees: Cognitive dissonances between self-reports and supervisor-ratings

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    Primary data was obtained from six retail outlets of a large global retailer to determine the self-reported job performance expectations (E) and perceptions (P) of 292 employees and the perceptions of 106 supervisors about their subordinates’ actual job achievements. Unlike past studies, the focus of this study was on internal rather than the ubiquitous external customers’ views on the performance quality and productivity of retail employees. The survey revealed that employees’ performance expectations were much higher than their self-reported and the supervisors’ perceptions of employees’ performance. Although there were marginal differences in the mean scores between employees’ and supervisors’ perceptions, the average differences between the retail employees’ expectations and their self-reported perceptions (Ee – Pe values), as well as between their expectations and the supervisors’ perceptions (Ee – Ps values) of employees’ performance were between 0.82 and 1.57. Using Anderson’s (1973) expectation disconfirmation theory (EDT) this article analyses and discusses the cognitive dissonance between two performance evaluator

    Quantum Magnetization Plateau in Spin-1 Triangular-Lattice Antiferromagnet Ba3_3NiSb2_2O9_9

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    We report the results of magnetization and specific heat measurements on Ba3_3NiSb2_2O9_9, which is a quasi-two-dimensional spin-1 triangular-lattice antiferromagnet. We observed a nonclassical magnetization plateau at one-third of the saturation magnetization that is driven by spin frustration and quantum fluctuation. Exact diagonalization for a 21-site rhombic cluster was performed to analyze the magnetization process. Experimental and calculated results agree well.Comment: published in Journal of the Physical Society of Japan 80 (2011) 09370

    Antigen receptor repertoires of one of the smallest known vertebrates

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    The rules underlying the structure of antigen receptor repertoires are not yet fully defined, despite their enormous importance for the understanding of adaptive immunity. With current technology, the large antigen receptor repertoires of mice and humans cannot be comprehensively studied. To circumvent the problems associated with incomplete sampling, we have studied the immunogenetic features of one of the smallest known vertebrates, the cyprinid fish Paedocypris sp. “Singkep” (“minifish”). Despite its small size, minifish has the key genetic facilities characterizing the principal vertebrate lymphocyte lineages. As described for mammals, the frequency distributions of immunoglobulin and T cell receptor clonotypes exhibit the features of fractal systems, demonstrating that self-similarity is a fundamental property of antigen receptor repertoires of vertebrates, irrespective of body size. Hence, minifish achieve immunocompetence via a few thousand lymphocytes organized in robust scale-free networks, thereby ensuring immune reactivity even when cells are lost or clone sizes fluctuate during immune responses

    Thermodynamics of AdS/QCD

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    We study finite temperature properties of four dimensional QCD-like gauge theories in the gauge theory/gravity duality picture. The gravity dual contains two deformed 5d AdS metrics, with and without a black hole, and a dilaton. We study the thermodynamics of the 4d boundary theory and constrain the two metrics so that they correspond to a high and a low temperature phase separated by a first order phase transition. The equation of state has the standard form for the pressure of a strongly coupled fluid modified by a vacuum energy, a bag constant. We determine the parameters of the deformation by using QCD results for TcT_c and the hadron spectrum. With these parameters, we show that the phase transition in the 4d boundary theory and the 5d bulk Hawking-Page transition agree. We probe the dynamics of the two phases by computing the quark-antiquark free energy in them and confirm that the transition corresponds to confinement-deconfinement transition.Comment: 1+19 pages, 6 figures, references added, section 3 improve

    Supersymmetry and Branes in M-theory Plane-waves

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    We study brane embeddings in M-theory plane-waves and their supersymmetry. The relation with branes in AdS backgrounds via the Penrose limit is also explored. Longitudinal planar branes are originated from AdS branes while giant gravitons of AdS spaces become spherical branes which are realized as fuzzy spheres in the massive matrix theory.Comment: 17 pages, JHEP style, references added, typos correcte

    Chiral Phonons with Giant Magnetic Moments in a Topological Crystalline Insulator

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    We have studied the magnetic response of transverse optical phonons in Pb1−x_{1-x}Snx_{x}Te films. Polarization-dependent terahertz magnetospectroscopy measurements revealed Zeeman splittings and diamagnetic shifts, demonstrating that these phonon modes become chiral in magnetic fields. Films in the topological crystalline insulator phase (x>0.32x > 0.32) exhibited magnetic moment values that are larger than those for topologically trivial films (x<0.32x < 0.32) by two orders of magnitude. Furthermore, the sign of the effective gg-factor was opposite in the two phases, which can be explained by our theoretical model. These results strongly hint at the existence of interplay between the magnetic properties of chiral phonons and the topology of electronic band structure.Comment: 6 pages, 3 figures, see Supplemental Material in the Ancillary director

    Rare coding SNP in DZIP1 gene associated with late-onset sporadic Parkinson's disease

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    We present the first application of the hypothesis-rich mathematical theory to genome-wide association data. The Hamza et al. late-onset sporadic Parkinson's disease genome-wide association study dataset was analyzed. We found a rare, coding, non-synonymous SNP variant in the gene DZIP1 that confers increased susceptibility to Parkinson's disease. The association of DZIP1 with Parkinson's disease is consistent with a Parkinson's disease stem-cell ageing theory.Comment: 14 page

    Theoretical Studies of Spectroscopy and Dynamics of Hydrated Electrons.

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