841 research outputs found

    Signature of Spin Collective Mode in Local Tunneling Spectra of a d-wave Superconductor

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    We consider the influence of magnetic excitations on the local density of states in the d-wave superconductor. The magnetic susceptibility is calculated within the renormalized t−tâ€Č−Jt-t'-J model and its influence on the quasiparticle self-energy is considered using a minimal model originally proposed by Polkovnikov {\it et al.}[cond-mat/0203176]. We find the local density of states possess periodic components both along (π,0)(\pi,0) and (π,π)(\pi,\pi) directions with the associated wavevectors changing in magnitude as the quasiparticle energy is varied. Comparison with the STM experiment reveals that the calculated LDOS modulation is inconsistent with the measured data.Comment: Two figures separately attached as .jpg file

    Validity of the parabolic effective mass approximation in silicon and germanium n-MOSFETs with different crystal orientations

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    This paper investigates the validity of the parabolic effective mass approximation (EMA), which is almost universally used to describe the size and bias-induced quantization in n-MOSFETs. In particular, we compare the EMA results with a full-band quantization approach based on the linear combination of bulk bands (LCBB) and study the most relevant quantities for the modeling of the mobility and of the on-current of the devices, namely, the minima of the 2-D subbands, the transport masses, and the electron density of states. Our study deals with both silicon and germanium n-MOSFETs with different crystal orientations and shows that, in most cases, the validity of the EMA is quite satisfactory. The LCBB approach is then used to calculate the values of the effective masses that help improve the EMA accuracy. There are crystal orientations, however, where the 2-D energy dispersion obtained by the LCBB method exhibits features that are difficult to reproduce with the EMA model

    Entwicklung verdauungsresistenter Peptidantigene fĂŒr orale Impfstoffe

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    Die Entwicklung oraler Impfstoffe ist wegen der oft fehlenden VerdauungsstabilitĂ€t sehr komplex. Durch retro-inverse (RI) Peptide kann dieses Problem gelöst werden. Am Beispiel von HĂŒhner-Ovalbumin (OVA) wurden Verfahren entwickelt, um RI-Peptidantigene zu identifizieren und zu optimieren. Mit Hilfe eines neuen hochsensitiven Peptid-ELISAs wurden Antikörperproben von mit OVA immunisierten MĂ€usen untersucht. Via Ala-Scan wurden die fĂŒr die Bindung essentiellen AminosĂ€uren eines Epitops identifiziert, wobei sich eine hohe Korrelation zu deren OberflĂ€chenlage ergab. Auf dieser Basis wurde ein Sotware-Evolutionsalgorithmus entwickelt, der optimierte RI-Peptidmutanten erzeugte, deren Antikörperbindung in vitro bis zu 30mal höher als die des Originalpeptids war. Mit dem beschriebenen Verfahren lassen sich RI-Peptidantigene mit einer erheblich höheren Antikörperbindung als bisher entwickeln. RI-Peptide könnten sich so als attraktive Option fĂŒr die Entwicklung oraler Impfstoffe erweisen

    Transverse Enhancement Model and MiniBooNE Charge Current Quasi-Elastic Neutrino Scattering Data

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    Recently proposed Transverse Enhancement Model of nuclear effects in Charge Current Quasi-Elastic neutrino scattering [A. Bodek, H. S. Budd, and M. E. Christy, Eur. Phys. J. C{\bf 71} (2011) 1726] is confronted with the MiniBooNE high statistics experimental data. It is shown that the {\it effective} large axial mass model leads to better agreement with the data.Comment: 4 pages, 6 figure

    Segmented block copolymers with monodisperse hard segments:the influence of H-bonding on various properties

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    The properties of segmented-copolymer-based H-bonding and non-H-bonding crystallisable segments and poly(tetramethylene oxide) segments were studied. The crystallisable segments were monodisperse in length and the non-hydrogen-bonding segments were made of tetraamidepiperazineterephthalamide (TPTPT). The polymers were characterised by DSC, FT-IR, SAXS and DMTA. The mechanical properties were studied by tensile, compression set and tensile set measurements. The TPTPT segmented copolymers displayed low glass transition temperatures (Tg, −70 °C), good low-temperature properties, moderate moduli (Gâ€Č ≈ 10–33 MPa) and high melting temperatures (185–220 °C). However, as compared to H-bonded segments, both the modulus and the yield stress were relatively low

    Antiprogestagen RU486 prevents the LH-dependent decrease in the serum concentrations of inhibin in the rat

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    1. In the rat, the LH-dependent ovarian progesterone rise mediates several actions of the primary surge of LH on the ovary. This experiment was aimed at elucidating the effects of the antiprogestagen RU486 on the LH- dependent decrease in both the serum concentrations and the ovarian content of inhibin. 2. All rats in this experiment were treated with an antagonist of LHRH (1 mg/200 ÎŒl saline at 0800 b in proestrus) to supress the endogenous release of LH. One group of rats received 32 ÎŒg LH/250 ÎŒl saline at 1200h in proestrus. Other group was given 4 mg RU486/200 ÎŒl oil at 0800 h in proestrus. The third group was injected with both RU486 and LH. Rats from the control group were injected with 250 ÎŒl saline and 200 ÎŒl oil. Animals were decapitated at 1700 h in proestrus and trunk blood and ovaries collected to determine the serum concentrations of LH, FSH, progesterone, 17ÎČ-estradiol and inhibin as well as the ovarian content of inhibin. 3. The ovulatory dose of LH in LHRHα-treated rats decreased both the serum concentrations and the ovarian content of inhibin and increased the serum concentrations of FSH. The administration of RU486 blocked the effect of LH on the serum concentrations of inhibin but not that on the ovarian content of inhibin. 4. Since the antiprogestagen RU486 blocked the effect of LH on the serum concentrations of inhibin, we conclude that ovarian progesterone, besides mediating the effects of the primary LH surge on the ovulatory process and luteinization, participates in the LH-dependent drop in the serum concentrations of inhibin in proestrous afternoon

    Bryophytes of Uganda : 6., new and additional records, 3.

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    12 hepatics and 32 mosses are reported new to Uganda, 1 moss being also new to Africa, and 1 liverwort new to mainland Africa. Ectropothecium plumigerum (Broth.) HedenĂ€s is a new combination (basionym: Isopterygium plumigerum Broth.) with a new synonym Taxicaulis plumirameus MĂŒll.Hal. nom. nud., and Taxiphyllum maniae (Renauld & Paris) M. Fleisch. is a new synonym of Taxiphyllum taxirameum (Mitt.) M.Fleisch. Three mosses are removed from the Uganda list
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