12,151 research outputs found

    Comparisons of soil suction induced by evapotranspiration and transpiration of S. <i>heptaphylla</i>

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    For a given evapotranspiration (ETr), both soil evaporation and plant transpiration (Tr) would induce soil suction. However, the relative contribution of these two processes to the amount of suction induced is not clear. The objective of this study is to quantify ETr- and Tr-induced suction by a selected tree species, Scheffllera heptaphylla, in silty sand. The relative contribution of transpiration and evaporation to the responses of suction is then explored based on observed differences in Tr- and ETr-induced suction. In total, 12 test boxes were used for testing: 10 for vegetated soil with different values of leaf area index (LAI) and root area index (RAI), while two were for bare soil as references. Each box was exposed to identical atmospheric conditions controlled in a plant room for monitoring suction responses over a week. Due to the additional effects of soil evaporation, ETr-induced suction could be 3%–47% higher than Tr-induced suction, depending on LAI. The significance of evaporation reduced substantially when LAI was higher, as relatively less radiant energy fell on the soil surface for evaporation. For a given LAI, the effects of evaporation were less significant at deeper depths within the root zone. The effects of RAI associated with root-water uptake upon transpiration were the dominant process of ETr affecting the suction responses.</jats:p

    A citation study of Annals of Library and Information Studies (ALIS) andDESIDOC Journal of Library and Information Technology (DJLIT)

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    The study presents an analysis of the number of articles published in Annals of Library and Information Studies (ALIS)and DESIDOC Journal of Library and Information Technology (DJLIT) during 2010-2013 and the citations obtained bythese articles during 2010-2014 (April) using Google. The study develops immediacy index and impact factor of the twojournals, besides, identifying the highly cited authors/papers. Findings reveal that DJLIT published more papers than ALISand also received more citations. However, citation per paper for both the journals is almost equal. DJLIT have a betterimmediacy index than ALIS. Impact factor of both the journals was less than one in 2012; however, it increased in 2013 andwas more than one in 2013

    Top Yukawa coupling measurement with indefinite CP Higgs in e+ettˉΦe^+e^-\to t\bar{t}\Phi

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    We consider the issue of the top quark Yukawa coupling measurement in a model in dependent and general case with the inclusion of CP-violation in the coupling. Arguably the best process to study this coupling is the associa ted production of Higgs boson along with a ttˉt\bar t pair in a machine like the International Linear Collider (ILC). While detailed analyses of the sensitivity of the measurement assuming a Standard Model (SM) - like coupling are available in the context of ILC, conclude that th e coupling could be pinned down at about 10\% level with modest luminosity, our investigations show that the scenario could be different in case of a more general coupling. The modified Lorentz structure resulting in a changed functional dependence of the cross section on the couplin g, along with the difference in the cross section itself leads to considerable deviation in the sensitivity. Our studies with an ILC of center of mass energies of 500 GeV, 800 GeV and 1000 GeV show that moderate CP-mixing in the Higgs sector could change the sensitivity to about 20\ %, while it could be worsened to 75\% in cases which could accommodate more dramatic changes in the coupling. While detailed considerations of the decay distributions point to a need for a relook at the analysis strategy followed for the case of SM such as for a model independent analysis of the top quark Yukawa coupling measurement. This study strongly suggests that, a joint analysis of the CP properties and the Yukawa coupling measurement would be the way forward at the ILC and that caution must be excercised in the measurem ent of the Yukawa couplings and the conclusions drawn from it.Comment: 18 pages, 7 figures, uses revte

    Effect of volcanic debris on stratospheric ion conductivity

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    The reduction is reported of stratospheric ion conductivities in the altitude range of 20 to 27 km attributable to the aerosols injected into the stratosphere by the eruption of volcano Nevado Del Ruiz on November 13, 1985. Three balloon experiments were conducted from Hyderabad, India (17.5 N, 78.6 E) carrying a Langmuir probe payload for measuring stratospheric ion conductivities. The first flight took place about 9 months before the volcanic eruption, the second 3 weeks after the eruption and the third about a year later. Lidar observations from Japan, Hawaii and Europe reported detection of aerosol layers in the 18 to 25 km altitude range attributable to the Nevado Del Ruiz volcanic eruption. A comparison of the conductivity profiles shows that the reduction of ion conductivities is: 57.3 percent at 20 km and 31 percent at 25 km. A year after the eruption, conductivities at all heights tended to recover

    Cycloadditions of cyclohexynes and cyclopentyne.

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    We report the strategic use of cyclohexyne and the more elusive intermediate, cyclopentyne, as a tool for the synthesis of new heterocyclic compounds. Experimental and computational studies of a 3-substituted cyclohexyne are also described. The observed regioselectivities are explained by the distortion/interaction model

    Oscillatory Tunnel Splittings in Spin Systems: A Discrete Wentzel-Kramers-Brillouin Approach

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    Certain spin Hamiltonians that give rise to tunnel splittings that are viewed in terms of interfering instanton trajectories, are restudied using a discrete WKB method, that is more elementary, and also yields wavefunctions and preexponential factors for the splittings. A novel turning point inside the classically forbidden region is analysed, and a general formula is obtained for the splittings. The result is appled to the \Fe8 system. A previous result for the oscillation of the ground state splitting with external magnetic field is extended to higher levels.Comment: RevTex, one ps figur

    Quenched Spin Tunneling and Diabolical Points in Magnetic Molecules: II. Asymmetric Configurations

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    The perfect quenching of spin tunneling first predicted for a model with biaxial symmetry, and recently observed in the magnetic molecule Fe_8, is further studied using the discrete phase integral (or Wentzel-Kramers-Brillouin) method. The analysis of the previous paper is extended to the case where the magnetic field has both hard and easy components, so that the Hamiltonian has no obvious symmetry. Herring's formula is now inapplicable, so the problem is solved by finding the wavefunction and using connection formulas at every turning point. A general formula for the energy surface in the vicinity of the diabolo is obtained in this way. This formula gives the tunneling apmplitude between two wells unrelated by symmetry in terms of a small number of action integrals, and appears to be generally valid, even for problems where the recursion contains more than five terms. Explicit results are obtained for the diabolical points in the model for Fe_8. These results exactly parallel the experimental observations. It is found that the leading semiclassical results for the diabolical points appear to be exact, and the points themselves lie on a perfect centered rectangular lattice in the magnetic field space. A variety of evidence in favor of this perfect lattice hypothesis is presented.Comment: Revtex; 4 ps figures; follow up to cond-mat/000311

    Dichloro(diphenylarsino)ruthenium(III) & Its Reactions with Some Nitrogen Donors

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    Bibliometrics and scientometrics in India: An overview of studies during 1995-2014, Part I: Indian publication output and its citation impact

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    An analysis of 801 papers published in the area of bibliometrics and scientometrics during 1995-2014 indicates a steep increase in the number of papers published by Indian researchers as compared to the number of papers published during 1970-1994. This indicates a growing interest of Indian scholars in scientometrics and bibliometrics. The paper provides several reasons for this steep increase. The main focus of research is on bibliometric assessment of India and other countries followed by cross national assessment and bibliometric analysis of individual journals. CSIR-NISTADS is the top producing institute contributing about one-third (31.4%) of the total output followed by the output of Bhabha Atomic Research Centre and CSIR-NISCAIR. The distribution of citation data indicates that about one-fifth (21.7%) papers remained uncited. The paper identifies journals in which these uncited papers were published. Only 15% papers were cited more than 20 times. Most of the prolific authors as well as highly cited authors were from the institutions belonging to the Council of Scientific and Industrial Research. Among all authors B.M. Gupta (CSIR-NISTADS) produced the highest number of papers, but the impact as seen in terms of citation per paper and relative citation impact, S. Arunachalam (MSSRF) topped the list
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