13,843 research outputs found

    Light-cone Gauge Superstring Field Theory and Dimensional Regularization II

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    We propose a dimensional regularization scheme to deal with the divergences caused by colliding supercurrents inserted at the interaction points, in the light-cone gauge NSR superstring field theory. We formulate the theory in dd dimensions and define the amplitudes as analytic functions of dd. With an appropriately chosen three-string interaction term and large negative dd, the tree level amplitudes for the (NS,NS) closed strings can be recast into a BRST invariant form, using the superconformal field theory proposed in Ref.[arXiv:0911.3704]. We show that in the limit d10d \to 10 they coincide with the results of the first quantized theory. Therefore we obtain the desired results without adding any contact interaction terms to the action.Comment: 23 pages; v2: minor modifications; v3: revised argument in section 3, added appendix C, results unchanged; v4: added clarifications, two figures and a footnote; v5: minor modification

    D-brane States and Disk Amplitudes in OSp Invariant Closed String Field Theory

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    We construct solitonic states in the OSp invariant string field theory, which are BRST invariant in the leading order of regularization parameter ϵ\epsilon. We calculate the disk amplitudes using these solitonic states and show that they describe D-branes and ghost D-branes.Comment: 37 pages, 8 figure

    Epitaxial designs for maximizing efficiency in resonant tunnelling diode based terahertz emitters

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    We discuss the modelling of high current density InGaAs/AlAs/InP resonant tunneling diodes to maximize their efficiency as THz emitters. A figure of merit which contributes to the wall plug efficiency, the intrinsic resonator efficiency, is used for the development of epitaxial designs. With the contribution of key parameters identified, we analyze the limitations of accumulated stress to assess the manufacturability of such designs. Optimal epitaxial designs are revealed, utilizing thin barriers, with a wide and shallow quantum well that satisfies the strained layer epitaxy constraint. We then assess the advantages to epitaxial perfection and electrical characteristics provided by devices with a narrow InAs sub-well inside a lattice-matched InGaAs alloy. These new structures will assist in the realization of the next-generation submillimeter emitters

    Activation cross-sections of deuteron induced nuclear reactions on neodymium up to 50 MeV

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    In the frame of a systematic study of activation cross sections of deuteron induced nuclear reactions on rare earths, the reactions on neodymium for production of therapeutic radionuclides were measured for the first time. The excitation functions of the natNd(d,x) 151,150,149,148m,148g,146,144,143Pm, 149,147,139mNd, 142Pr and 139gCe nuclear reactions were assessed by using the stacked foil activation technique and high resolution $\gamma@-spectrometry. The experimental excitation functions were compared to the theoretical predictions calculated with the modified model codes ALICE-IPPE-D and EMPIRE-II-D and with the data in the TENDL-2012 library based on latest version of the TALYS code. The application of the data in the field of medical isotope production and nuclear reaction theory is discussed

    Activation cross-sections of longer lived products of deuteron induced nuclear reactions on ytterbium up to 40 MeV

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    In the frame of a systematic study of the activation cross-sections of the deuteron induced nuclear reactions, excitation functions of the natYb(d,xn)177,173,172mg,171mg,170,169Lu, natYb(d,x)175,169Yb and natYb(d,x)173,172,168,167,165Tm reactions are studied up to 40 MeV, a few of them for the first time. Cross-sections were measured with the activation method using a stacked foil irradiation technique and high resolution gamma-ray spectrometry. The experimental data are analyzed and compared to the results of the theoretical model codes ALICE-IPPE, EMPIRE-II and TALYS. From the measured cross-section data integral production yields were calculated. Applications of the new cross-sections are discussed

    Compositon of Tantalum Nitride Thin Films Grown by Low-Energy Nitrogen Implantation: A Factor Analysis Study of the Ta 4f XPS Core Level

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    Tantalum nitride thin films have been grown by in situ nitrogen implantation of metallic tantalum at room temperature over the energy range of 0.5-5keV. X-ray photoelectron spectroscopy (XPS) and Factor Analysis (FA) have been used to characterise the chemical composition of the films. The number of the different Ta-N phases formed during nitrogen implantation, as well as their spectral shape and concentrations, have been obtained using principal component analysis (PCA) and iterative target transformation factor analysis (ITTFA), without any prior assumptions. According to FA results, the composition of the tantalum nitride films depends on both the ion dose and ion energy, and is mainly formed by a mixture of metallic tantalum, beta-TaN0.05, gamma-Ta2N and cubic/hexagonal TaN phases.Comment: 24 pages, 5 figures submitted to Applied Physics

    Rumen Fermentation, Blood Metabolites, and Performance of Sheep Fed Tropical Browse Plants

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    The in vitro study was designed to evaluate total gas production, dry matter degradability (DMD), and VFA profile; while in vivo study was designed to evaluate nutrient intakes, blood metabolites, and performance of sheep fed native grass mixed with Calliandra calothyrrus (CC), Leucaena leucochepala (LL), Moringa oleifera (MO), Gliricidea sepium (GS), and Artocarpus heterophyllus (AH). The best three from the in vitro results were used to formulate diets in in vivo study. Sixteen male growing sheep (average BW 20 kg) were fed 100% native grass (NG) as control; 70% NG + 30% GS; 70% NG + 30% MO; and 70% NG + 30% AH. Nutrient consumptions, DMD, blood metabolites, and sheep performances were analyzed by using Completely Randomized Design. The in vitro results showed that the total gas production and DMD of CC and LL were the lowest (P<0.05) while the highest was found in GS, MO, and AH treatments (P<0.05). Meanwhile, the in vivo results showed that nutrient intakes (DM, CP, and CF) of GS and AH rations were the highest. The ADG, concentration of albumin, and globulin in all treatments were similar, while total serum protein, triglycerides, and glucose concentration in MO and AH rations were higher than others. Serum cholesterol concentration in MO ration was the lowest, meanwhile the concentration of IgG was the highest (P<0.05). Supplementation of 30% MO was the best choice for optimum rumen fermentation and maintaining health status of local sheep
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