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961.
Herbert?Due?as Edmundo?J.?HuertasEmail author Francisco?Marcellán 《Numerical Algorithms》2012,60(1):51-73
In this contribution we consider the asymptotic behavior of sequences of monic polynomials orthogonal with respect to a Sobolev-type
inner product
$ \left\langle p,q\right\rangle _{S}=\int_{0}^{\infty }p(x)q(x)x^{\alpha }e^{-x}dx+Np^{\prime }(a)q^{\prime }(a),\alpha >-1 $ \left\langle p,q\right\rangle _{S}=\int_{0}^{\infty }p(x)q(x)x^{\alpha }e^{-x}dx+Np^{\prime }(a)q^{\prime }(a),\alpha >-1 相似文献
962.
Gabriel Di Lemos Santiago Lima Rafael Chaves Sebastião Alves Dias 《Annals of Physics》2012,327(6):1435-1449
We consider chiral fermions interacting minimally with abelian and non-abelian gauge fields. Using a path integral approach and exploring the consequences of a mechanism of symmetry restoration, we show that the gauge anomaly has null expectation value in the vacuum for both cases (abelian and non-abelian). We argue that the same mechanism has no possibility to cancel the chiral anomaly, what eliminates competition between chiral and gauge symmetry at full quantum level. We also show that the insertion of the gauge anomaly in arbitrary gauge invariant correlators gives a null result, which points towards anomaly cancellation in the subspace of physical state vectors. 相似文献
963.
L. N. Coelho B. Diaz R. Magalhães-Paniago A. Malachias 《The European physical journal. Special topics》2012,208(1):217-229
In this work we depict schematically the use of resonant (anomalous) X-ray diffraction as a tool to directly probe strain
and composition of self-assembled semiconductor islands. By employing a direct analysis at the Eu L3 edge its composition gradient is quantified for EuTe:SnTe capped islands. Projection maps are proposed to visualize the results,
providing an alternative capability to infer quantum dot properties. A more complex methodology is applied to the study of
InP:GaAs islands, in which complementary anomalous measurements are performed. For this system the number of samples analyzed
allows us to extract the activation energy for Ga adatoms diffusion from the substrate to the islands. 相似文献
964.
João Eduardo Borges Nuno H. C. Pereira Jorge Matos Kathleen H. Frizell 《Experiments in fluids》2010,48(1):17-31
The development of a three-hole pressure probe with back-flushing combined with a conductivity probe, used for measuring simultaneously
the magnitude and direction of the velocity vector in complex air–water flows, is described in this paper. The air–water flows
envisaged in the current work are typically those occurring around the rotors of impulse hydraulic turbines (like the Pelton
and Cross-Flow turbines), where the flow direction is not known prior to the data acquisition. The calibration of both the
conductivity and three-hole pressure components of the combined probe in a rig built for the purpose, where the probe was
placed in a position similar to that adopted for the flow measurements, will be reported. After concluding the calibration
procedure, the probe was utilized in the outside region of a Cross-Flow turbine rotor. The experimental results obtained in
the present study illustrate the satisfactory performance of the combined probe, and are encouraging toward its use for characterizing
the velocity field of other complex air–water flows. 相似文献
965.
Y.A. Coutinho J.A. Martins Simões C.M. Porto 《The European Physical Journal C - Particles and Fields》2001,18(4):779-784
In this paper we discuss a left–right symmetric model for elementary particles and their connection with the mass spectrum
of elementary fermions. The model is based on the group . New mirror fermions and a minimal set of Higgs particles that break this symmetry down to are proposed. The model can accommodate a consistent pattern for charged and neutral fermion masses as well as neutrino oscillations.
An important consequence of the model is that the connection between the left and right sectors can be implemented by the
neutral vector gauge boson Z and a new heavy Z'.
Received: 15 June 2000 / Revised version: 14 September 2000 / Published online: 5 February 2001 相似文献
966.
Alberto H. V. Vilão R. C. Piroto Duarte J. Gil J. M. Ayres de Campos N. Lichti R. L. Davis E. A. Cottrell S. P. Cox S. F. J. 《Hyperfine Interactions》2001,136(3-8):471-477
The hyperfine spectroscopy of muonium in II–VI semiconductors is reviewed, suggesting that whereas hydrogen is a deep-level
defect in ZnS, ZnSe and ZnTe, it constitutes a shallow donor in ZnO, CdS, CdSe and CdTe. Shallow and deep states coexist in
CdTe. Using new data for ZnO, it is shown that the principal values of the muonium hyperfine tensor may be obtained with equal
facility from measurements in longitudinal or in transverse magnetic field, and from samples that are polycrystalline powders
or single crystals. Spin density on the central muon in the shallow states correlates with the electron binding energy or
donor depth.
This revised version was published online in September 2006 with corrections to the Cover Date. 相似文献
967.
The rates of electron transfer reactions in azurin and plastocyanin are calculated with the Intersecting-State Model and compared with experimental data. The calculated distance, free-energy and temperature dependencies of the intraprotein rates in Ru-modified azurins are in good agreement with the experiment. These calculations do not require the fitting of any parameters. Significant tunneling contributions to the room temperature rate are found in some systems. In some cases the symmetry or the orientation of the donor and acceptor orbitals are not favorable and the ET rates are reduced by factors exceeding 4 orders of magnitude. 相似文献
968.
Liquid chromatography/mass spectrometry (LC/MS) is now considered to be the most promising analytical method for the determination of biological substances, especially nonvolatile or highly polar substances However, some compounds do not show enough sensitivity in LC/MS and soft ionization methods commonly used in LC/MS, such as electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI), sometimes do not give satisfactory structural information This report presents an overview 相似文献
969.
1 Introduction Gaschromatography/massspectrometry (GC/MS)andliquidchromatography/massspectrometry (LC/MS) ,representativesofthehyphenatedtechniques ,aresomeofthemostreliableanalyticalmethods ,whicharethesynergisticcombinationoftwopowerfulanalyticaltechniques;… 相似文献
970.
Joaquim C. G. Esteves da Silva Jos R. M. Dias Jú lia M. C. S. Magalh es 《Analytica chimica acta》2001,450(1-2):175-184
A chemiluminescent flow system for bromate detection, based on the reaction of bromate with sulphite in acid medium and using the steroid hydrocortisone as sensitiser, was studied. A factorial analysis strategy for the study of the effect on the system response of the experimental factors, flow rates of two pumps (Q1 — acid sulphite plus hydrocortisone aqueous solution; Q2 — carrier, water), sample injection volume (VL), reactor volume (VR), sulphite concentration (CS), hydrocortisone concentration (CH) and acid concentration (CA), was used. Screening analysis of the system performance was made using Plackett Burman designs. The system optimisation procedure was achieved by three levels three factors full factorial designs. VL and CH are the most significant factors — a quadratic CH term was also observed to be significant. The optimised system responded linearly (logarithm of the detector signal as function of the logarithm of the bromate concentration) in the concentration range between 3.6×10−7 and 5.0×10−4 M with a limit of detection of about 8.0×10−8 M (about 10 microg/l). An analysis of some interfering ions was made and it was suggested that bromide and chloride begin to quench chemiluminescence when they are in a 10-fold excess relatively to bromate concentration. 相似文献
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