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51.
We present the first calculation of the transverse spin structure of the pion in lattice QCD. Our simulations are based on two flavors of nonperturbatively improved Wilson fermions, with pion masses as low as 400 MeV in volumes up to (2.1 fm)(3) and lattice spacings below 0.1 fm. We find a characteristic asymmetry in the spatial distribution of transversely polarized quarks. This asymmetry is very similar in magnitude to the analogous asymmetry we previously obtained for quarks in the nucleon. Our results support the hypothesis that all Boer-Mulders functions are alike.  相似文献   
52.
One of the hardest problems in coding theory is to evaluate the covering radius of first order Reed–Muller codes RM(1,m), and more recently the balanced covering radius for crypto graphical purposes. The aim of this paper is to present some new results on this subject. We mainly study boolean functions invariant under the action of some finite groups, following the idea of Patterson and Wiedemann [The covering radius of the (1, 15) Reed-Muller Code is atleast 16276. IEEE Trans Inform Theory. Vol. 29 (1983) 354.]. Our method is Fourier transforms and our results are both theoretical and numerical.  相似文献   
53.
The purpose of this paper is to extend Bell's inequalities to obtain some general necessary conditions for the existence of a joint probability distribution for any finite collection of Bell-type random variables. Our results show that forN > 4 many new elementary inequalities beyond those of Bell must be satisfied by any hidden variable theory.  相似文献   
54.
Anodic aluminium oxide (AAO) membranes are macroscopically highly ordered systems made of oriented nano-scale parallel cylindrical channels. The membrane topology is defined by the pore radius, the inter-pores distance and the pore length. We show by a combined SANS and SEM study that the membrane morphology can be tailored by the main anodization parameters: voltage, temperature and anodization duration. We show that the confinement of an hydrophilic polymer (poly(ethylene oxide)) inside the pores is possible. We observe a striking effect of the confinement on the polymer mean-square displacement as measure by high resolution neutron quasi-elastic scattering.  相似文献   
55.
The delay time of ignition of a composite propellant based on ammonium perchlorate by a CO2-laser is measured at various pressures and radiant flux densities. The characteristics of the propellant at the moment of ignition are calculated. The obtained rate constants of the reactions in the propellant are compared to the respective rate constants of the reactions in the c-phase occurring during the combustion of the composite propellant.  相似文献   
56.
We present the first results for the K13 form factor from simulations with 2+1 flavors of dynamical domain wall quarks. Combining our result, namely, f+(0)=0.964(5) with the latest experimental results for Kl3 decays leads to |V us|=0.2249(14), reducing the uncertaintity in this important parameter. For the O(p6) term in the chiral expansion we obtain Delta f=-0.013(5).  相似文献   
57.
58.
The influence of the α-substitution on hydantoin formation from urethan protected alaninamide derivatives is investigated. Several 5-methyl-5-substituted hydantoins, obtained from 5-amino-5-methylhydantoin, are described.  相似文献   
59.
In this work, a method for the analysis of tin(II) and tin(IV) traces by stripping voltammetry in an aqueous medium and in methanol is reported. The advantages of using methanol as a solvent, which does not leave any residual current even at very negative potentials, are illustrated. Thus, in this medium, it is possible to perform the simultaneous analysis of traces of tin(II) and other cations which have much more negative dissolution potentials.  相似文献   
60.
The existence of a protein dynamic transition around 220 K is widely known and the central role of the protein hydration shell is now largely recognized as the driving force for this transition. In this paper, we propose a mechanism, at the molecular level, for the contribution of hydration water. In particular, we identify the key importance of rotational motion of the hydration water as a source of configurational entropy triggering (i) the 220 K protein dynamic crossover (the so-called dynamic transition) but also (ii) a much less intense and scarcely reported protein dynamic crossover, associated to a calorimetric glass transition, at 150 K.  相似文献   
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