828 research outputs found

    Necessity of integral formalism

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    To describe the physical reality, there are two ways of constructing the dynamical equation of field, differential formalism and integral formalism. The importance of this fact is firstly emphasized by Yang in case of gauge field [Phys. Rev. Lett. 33 (1974) 445], where the fact has given rise to a deeper understanding for Aharonov-Bohm phase and magnetic monopole [Phys. Rev. D. 12 (1975) 3845]. In this paper we shall point out that such a fact also holds in general wave function of matter, it may give rise to a deeper understanding for Berry phase. Most importantly, we shall prove a point that, for general wave function of matter, in the adiabatic limit, there is an intrinsic difference between its integral formalism and differential formalism. It is neglect of this difference that leads to an inconsistency of quantum adiabatic theorem pointed out by Marzlin and Sanders [Phys. Rev. Lett. 93 (2004) 160408]. It has been widely accepted that there is no physical difference of using differential operator or integral operator to construct the dynamical equation of field. Nevertheless, our study shows that the Schrodinger differential equation (i.e., differential formalism for wave function) shall lead to vanishing Berry phase and that the Schrodinger integral equation (i.e., integral formalism for wave function), in the adiabatic limit, can satisfactorily give the Berry phase. Therefore, we reach a conclusion: There are two ways of describing physical reality, differential formalism and integral formalism; but the integral formalism is a unique way of complete description.Comment: 13Page; Schrodinger differential equation shall lead to vanishing Berry phas

    Functional properties of two mutants of human glucose 6-phosphate dehydrogenase, R393G and R393H, corresponding to the clinical variants G6PD Wisconsin and Nashville

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    AbstractTwo severe Class I human glucose-6-phosphate dehydrogenase (G6PD, EC1.1.1.49) mutations, G6PDWisconsin (nt1177 C→G, R393G) and G6PDNashville (nt1178 G→A, R393H), affect the same codon, altering a residue in the dimer interface close to the “structural” NADP+ site. These mutations are predicted to influence interaction with the bound “structural” NADP+, long supposed to be crucial for enzyme stability. Recombinant proteins corresponding to these mutants have been constructed, expressed and purified to homogeneity. Steady-state kinetic parameters of the mutant enzymes were comparable to those of normal human G6PD, indicating that the mutations do not alter catalytic efficiency drastically. However, investigations of thermostability, urea denaturation, protease digestion, and hydrophobic exposure demonstrated that G6PD R393H is less stable than normal G6PD or R393G, and stability was more NADP+-dependent. Apoenzymes were prepared by removal of “structural” NADP+. Again the G6PDNashville protein was markedly less stable, and its dissociation constant for “structural” NADP+ is ∌500 nM, about 10 times higher than values for R393G (53 nM) and normal G6PD (37 nM). These results, together with structural information, suggest that the instability of the R393H protein, enhanced by the weakened binding of “structural” NADP+, is the likely cause of the severe clinical manifestation observed for G6PDNashville. They do not, however, explain the basis of disease in the case of G6PDWisconsin

    Structure determination of PF3 adsorption on Cu(100) using X-ray standing waves

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    The local structure of the Cu(100)c(4x2)-PF3 adsorption phase has been investigated through the use of normal-incidence X-ray standing waves (NIXSW), monitored by P 1s and F 1s photoemission, together with P K-edge near-edge X-ray absorption fine structure (NEXAFS). NEXAFS shows the molecule to be oriented with its C3v symmetry axis essentially perpendicular to the surface, while the P NIXSW data show the molecule to be adsorbed in atop sites 2.37±0.04 Å above the surface, this distance corresponding to the Cu-P nearest-neighbour distance in the absence of any surface relaxation. F NIXSW indicates a surprisingly small height difference of the P and F atoms above the surface 0.44±0.06 Å, compared with the value expected for an undistorted gas-phase geometry of 0.77 Å, implying significant increases in the F-P-F bond angles. In addition, however, the F NIXSW data indicate that the molecules have a well-defined azimuthal orientation with a molecular mirror plane aligned in a substrate mirror plane, and with a small (5-10°) tilt of the molecule in this plane such that the two symmetrically-equivalent F atoms in each molecule are tilted down towards the surface

    The Bulk RS KK-gluon at the LHC

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    We study the possibility of discovering and measuring the properties of the lightest Kaluza-Klein excitation of the gluon in a Randall-Sundrum scenario where the Standard Model matter and gauge fields propagate in the bulk. The KK-gluon decays primarily into top quarks. We discuss how to use the ttˉt \bar{t} final states to discover and probe the properties of the KK-gluon. Identification of highly energetic tops is crucial for this analysis. We show that conventional identification methods relying on well separated decay products will not work for heavy resonances but suggest alternative methods for top identification for energetic tops. We find, conservatively, that resonances with masses less than 5 TeV can be discovered if the algorithm to identify high pTp_T tops can reject the QCD background by a factor of 10. We also find that for similar or lighter masses the spin can be determined and for lighter masses the chirality of the coupling to ttˉt\bar t can be measured. Since the energetic top pair final state is a generic signature for a large class of new physics as the top quark presumably couples most strongly to the electroweak symmetry breaking sector, the methods we have outlined to study the properties of the KK-gluon should also be important in other scenarios.Comment: 21 pages, 13 figure

    Meaning in the traditional Chinese house and garden

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    Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Architecture, 1992.Includes bibliographical references (leaves 73-75).The thesis deals with the various levels of meanings of the Chinese house and garden, and how the meanings operated in the context of traditional daily life. It is approached from the point of view of meaning in the context of daily life, using the activities and events of daily life described in The Dream of the Red Chamber as examples. An eighteenth century masterpiece, the book is regarded as authentically representing the life of the upper class of its time. In the book, the author uses the garden and house proper as the settings two different worlds of daily life activities of a family. The world in the house represents Confusian order, conforming with the social order, and that of the garden a poetic entity dominated by the Taoist ideal. The house was the microcosm of society, and the garden the microcosm of the universe. Reading beyond this level, we find one was built upon the demand of control over the individual; the other upon the desire of the individual for relief from tight control. The two worlds in the home environment represented the world of men and the world of nature. In the world of the house, i. e. the world of men, the individual had to deal with all kinds of human relationships, by following the social rules that were designed to sustain the hierarchical structure of the society. In the world of the garden, i.e. the world of the nature, the individual became one with the universe, by following the ultimate standards of Tao.by Tao Li.M.S

    Supersymmetry and the positron excess in cosmic rays

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    Recently the HEAT balloon experiment has confirmed an excess of high-energy positrons in cosmic rays. They could come from annihilation of dark matter in the galactic halo. We discuss expectations for the positron signal in cosmic rays from the lightest superpartner. The simplest interpretations are incompatible with the size and shape of the excess if the relic LSPs evolved from thermal equilbrium. Non-thermal histories can describe a sufficient positron rate. Reproducing the energy spectrum is more challenging, but perhaps possible. The resulting light superpartner spectrum is compatible with collider physics, the muon anomalous magnetic moment, Z-pole electroweak data, and other dark matter searches.Comment: 4 pages, 2 figures, references added, minor wording change

    Twist-3 Distribute Amplitude of the Pion in QCD Sum Rules

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    We apply the background field method to calculate the moments of the pion two-particles twist-3 distribution amplitude (DA) ϕp(Ο)\phi_p(\xi) in QCD sum rules. In this paper,we do not use the equation of motion for the quarks inside the pion since they are not on shell and introduce a new parameter m0pm_0^p to be determined. We get the parameter m0p≈1.30GeVm_0^p\approx1.30GeV in this approach. If assuming the expansion of ϕp(Ο)\phi_p(\xi) in the series in Gegenbauer polynomials Cn1/2(Ο)C_n^{1/2}(\xi), one can obtain its approximate expression which can be determined by its first few moments.Comment: 12 pages, 3 figure

    Orbital stability: analysis meets geometry

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    We present an introduction to the orbital stability of relative equilibria of Hamiltonian dynamical systems on (finite and infinite dimensional) Banach spaces. A convenient formulation of the theory of Hamiltonian dynamics with symmetry and the corresponding momentum maps is proposed that allows us to highlight the interplay between (symplectic) geometry and (functional) analysis in the proofs of orbital stability of relative equilibria via the so-called energy-momentum method. The theory is illustrated with examples from finite dimensional systems, as well as from Hamiltonian PDE's, such as solitons, standing and plane waves for the nonlinear Schr{\"o}dinger equation, for the wave equation, and for the Manakov system

    New Insights of High-precision Asteroseismology: Acoustic Radius and χ

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    Asteroseismology is a powerful tool for probing stellar interiors and determining stellar fundamental parameters. In the present work, we adopt the χ2-minimization method but only use the observed high-precision seismic observations (i.e., oscillation frequencies) to constrain theoretical models for analyzing solar-like oscillator KIC 6225718. Finally, we find the acoustic radius τ0 is the only global parameter that can be accurately measured by the χ2-matching method between observed frequencies and theoretical model calculations for a pure p-mode oscillation star. We obtain τ0=4601.5−8.3+4.4 seconds for KIC 6225718. It leads that the mass and radius of the CMMs are degenerate with each other. In addition, we find that the distribution range of acoustic radius is slightly enlarged by some extreme cases, which posses both a larger mass and a higher (or lower) metal abundance, at the lower acoustic radius end
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