广义Bethe树上奇偶马尔可夫链场上的若干极限性质

通过构造两个非负鞅证明了一个强极限定理,然后把它应用到本文所定义的广义Bethe树上的奇偶马尔可夫链场上,从而获得了此马氏链场上的一类强极限定理.     

Current Status of Direct Solid Sampling for Electrothermal Atomic Absorption Spectrometry—A Critical Review of the Development between 1995 and 2005

Abstract

The literature about direct solid sampling (SS) and slurry sampling atomic absorption spectrometry (AAS) over the past decade has been surveyed critically. It became apparent that a very significant change had occurred, particularly in the relation between the two major techniques used for that purpose. In the 1990s, slurry sampling was typically considered the technique of choice, combining the significant advantages of the solid and the liquid sampling methods, at least in part because of the availability of a commercial accessory for automatic slurry sampling. The situation is completely inverted now, as the above accessory has been discontinued and rugged and reliable accessories for direct SS became available. Direct SS electrothermal (ET) AAS has been shown to provide the best limits of detection because of the absence of any dilution and a minimal risk of contamination. Calibration against aqueous standards appears to be feasible after careful program optimization. The absence of any significant sample handling makes SS ET AAS ideally suited for fast screening analyses. The introduction of high‐resolution continuum source AAS appears to open additional attractive features for SS ET AAS because of the significantly simplified optimization of furnace programs and the visibility of the spectral environment, which makes it easy to avoid spectral interferences. New calibration strategies make a “dilution” of samples unnecessary, which used to be one of the major limitations of SS ET AAS. Finally, direct SS analysis is an important contribution to clean chemistry, as practically no reagents are used.     

The shape of a vertically falling stream of a Newtonian liquid

Summary The diameters of the axially symmetric streams of two Newtonian liquids of different viscosities falling vertically under gravity have been measured as a function of the distance from the nozzle. The measurements have been compared with two theories, (I, II) based on different approximations. Theory I leads to a second-order ordinary differential equation and theory II gives an asymptotic solution of theNavier-Stokes equations. It was found that the first approach was sufficient to explain the measurements in the high viscosity liquid (30,000 cS) but the asymptotic solution was needed to explain the low viscosity (1,000 cS) measurements.

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Zusammenfassung Die Durchmesser der achsensymmetrischen Str?mungen zweier newtonischer Flüssigkeiten verschiedener Viskosit?ten, die unter ihrem Eigengewicht senkrecht austreten, werden als Funktion des Abstandes von einer Düse gemessen. Die Messungen werden mit zwei Theorien (I, II) verglichen, die auf verschiedene N?herungen beruhen. Die Theorie I führt auf eine gew?hnliche Differentialgleichung zweiter Ordnung, w?hrend die Theorie II eine asymptotische L?sung derNavier-Stokes-Gleichung ergibt. Es zeigt sich, da? die erste N?herung ausreicht, um die Messungen der hochviskosen Flüssigkeit (30.000 cS) zu beschreiben. Zur Erl?uterung der Messungen des niedrig-viskosen Silikon?ls (1.000 cS) bedarf es der asymptotischen L?sung.

     

Can Mycosporine‐Like Amino Acids Act as Multifunctional Compounds in Gymnodinium catenatum (Dinophyceae)?

MAAs originating from Gymnodinium catenatum were subjected to H₂O₂ oxidation, light and heat. Shinorine and porphyra‐334 were the more resistant to all treatments, mycosporine‐glycine (MYGL) was the least resistant to oxidation and heat, whereas palythene and M‐370 were the least resistant to light. MYGL and M‐311 were similarly resistant to photodegradation and oxidation in the dark and low temperature, but M‐311 was more resistant to oxidation under light or heat. The ratio M‐370/M‐365 changed from 29:1 to 6:1 ratio after 240 h of exposure to fluorescent light, indicating that M‐365 could represent the M‐370 cis‐isomer. The role of MAAs as antioxidants and/or osmolytes was evaluated by studying effects of abrupt salinity reduction. Both increases or decreases in concentrations were observed and were dependent on the MAA initial concentration and its chemical structure. The relative increase in MAAs with a known antioxidant capacity (MYGL, palythene) followed an exponential decay trend related to initial concentration. The relative decrease in highly polar MAAs (shinorine, porphyra‐334, M‐332) with a suspected osmolyte role followed a rise to a maximum with the increase in initial concentration. Whether or not MAAs play a significant role in osmoregulation, their loss can occur upon hypoosmotic shock.     

Minimal left-right symmetric models and new <Emphasis Type="Italic">Z</Emphasis>’ properties at future electron-positron colliders

It was recently shown that left-right symmetric models for elementary particles can be built with only two Higgs doublets. The general consequence of these models is that the left and right fermionic sectors can be connected by a new neutral gauge boson Z having its mass as the only additional new parameter. In this paper we study the influence of the fundamental fermionic representation for this new neutral gauge boson. Signals of possible new heavy neutral gauge bosons are investigated for the future electron-positron colliders at GeV, 1 TeV and 3 TeV. The total cross sections, forward-backward and left-right asymmetries and model differences are calculated for the process . Bounds on Z masses are estimated.Received: 4 May 2004, Revised: 22 September 2004, Published online: 9 November 2004     

Charged-particle pseudorapidity density distributions from Au+Au collisions at sqrt[s(NN)]=130 GeV

The charged-particle pseudorapidity density dN(ch)/d eta has been measured for Au+Au collisions at sqrt[s(NN)] = 130 GeV at RHIC, using the PHOBOS apparatus. The total number of charged particles produced for the 3% most-central Au+Au collisions for /eta/相似文献   

Centrality dependence of charged hadron transverse momentum spectra in Au+Au collisions from sqrt[s(NN)]=62.4 to 200 GeV

We have measured transverse momentum distributions of charged hadrons produced in Au+Au collisions at sqrt[s(NN)]=62.4 GeV. The spectra are presented for transverse momenta 0.25相似文献   

Temperature dependence of the universal contact parameter in a unitary Fermi gas

The contact I, introduced by Tan, has emerged as a key parameter characterizing universal properties of strongly interacting Fermi gases. For ultracold Fermi gases near a Feshbach resonance, the contact depends upon two quantities: the interaction parameter 1/(k(F)a), where k(F) is the Fermi wave vector and a is the s-wave scattering length, and the temperature T/T(F), where T(F) is the Fermi temperature. We present the first measurements of the temperature dependence of the contact in a unitary Fermi gas using Bragg spectroscopy. The contact is seen to follow the predicted decay with temperature and shows how pair-correlations at high momentum persist well above the superfluid transition temperature.