Double transverse-spin asymmetries in Drell–Yan processes with antiprotons

We present next-to-leading order predictions for double transverse-spin asymmetries in Drell–Yan dilepton production initiated by proton–antiproton scattering. The kinematic region of the proposed PAX experiment at GSI: 30?s?200 GeV²$30?s?200{\text{GeV}}^2$ and 2?M?7 GeV$2?M?7\text{GeV}$ is examined. The Drell–Yan asymmetries turn out to be large, in the range 20–40%. Measuring these asymmetries would provide the cleanest determination of the quark transversity distributions.     

Site-specific crosslinking of annexin proteins by 1,4-benzoquinone: a novel crosslinker for the formation of protein dimers and diverse protein conjugates

Annexin V (1) specifically binds to phosphatidylserine on apoptotic and necrotic cells as well as certain cancer cells, making it an attractive vehicle for the delivery of therapeutically-relevant conjugates to such sites. The wild-type protein possesses a single thiol at Cys316, which is difficultly accessible to site-specific labeling by simple maleimides. By contrast, 1,4-benzoquinone site-specifically labels annexin V in minutes. The resulting conjugate (5) serves as an intermediate for crosslinking annexin molecules, which can be accomplished within hours either directly for linking annexin V-128 (19), or via an extended sequence involving the crosslinking of two units of (5) by the symmetrical α,ω-dithiol (20). Besides its ability to mediate protein dimer formation while retaining annexin V's ability to bind phosphatidylserine, (5) possesses classic 1,4-benzoquinone reactivity. Various nucleophiles and Diels-Alder dienes form adducts with (5) in reactions that may have general utility for the synthesis of novel biologically active entities. The present work presents the first example of thiol-specific crosslinking of proteins by 1,4-quinone-based methodology designed to exploit the reactivity of this versatile chemical entity.     

有机硅活性中间体的研究 II. 一些含环丙基的有机硅化合物的合成及其结构

用锂有机物的方法合成了四种含有环丙基有机硅化合物,对上述每种化合物中可能存在着的立体异构进行了分离和和构型测定。     

On the scale variation of the total cross section for Higgs production at the LHC and at the Tevatron

We present a detailed study of the total pp cross section for scalar Higgs production to next-to-next-to-leading order in α_s at LHC energies, and of the pp̄ cross section at the Tevatron, combining an implementation of the solutions of the parton evolution equations at the three-loop order with the corresponding hard scatterings, evaluated at the same perturbative order. Our solutions of the DGLAP equations are implemented directly in x-space and allow for the study of the dependence of the results on the factorization (μ_F) and renormalization scales (μ_R) typical of a given process, together with the stability of the perturbative expansion. The input sets for the parton evolutions are those given by Martin, Roberts, Stirling and Thorne and by Alekhin. Results for K-factors are also presented. The NNLO corrections can be quite sizeable at typical collider energies. The stability region of the perturbative expansion is found when μ_R>m_H∼μ_F.     

The microwave heating of two-dimensional slabs with small Arrhenius absorptivity

The microwave heating of two-dimensional slabs in a long rectangularwaveguide propagating the TE₁₀ mode is examined. The temperaturedependency of the electrical conductivity and the thermal absorptivityis assumed to be governed by the Arrhenius law, while both theelectrical permittivity and the magnetic permeability are assumedconstant. The governing equations are the forced heat equationand the steady-state version of Maxwell's equation while theboundary conditions take into account both convective and radiativeheat loss. Approximate analytical solutions, valid for smallthermal absorptivity, are found for the temperature and theelectric-field amplitude using the Galerkin method. As the Arrheniuslaw is not amenable analytically, it is approximated by a rational-cubicfunction. At the steady state the temperature versus power relationshipis found to be multivalued; at the critical power level thermalrunaway occurs when the temperature jumps from the lower (cool)temperature branch to the upper (hot) temperature branch ofthe solution. In the steady-state limit the approximate analyticalsolutions are compared with the numerical solutions of the governingequations for various special cases. These are the limits ofsmall and large heat loss and an intermediate case involvingradiative heat loss. Results are also presented for a case wheredifferential cooling occurs on the different sides on the slab.An alternative heating scenario, where one end of the waveguideis blocked by a short, is also considered. The approximate solutionsare found for this geometry and compared in the small Biot-numberlimit to Kriegsmann (1997). Also, a control process is presented,which allows thermal runaway to be avoided and the desired finalsteady state to be reached. Various special cases of the feedbackparameters associated with the control process are examined.     

Bi-directional modulation of AMPA receptor unitary conductance by synaptic activity

Background  

Knowledge of how synapses alter their efficiency of communication is central to the understanding of learning and memory. The most extensively studied forms of synaptic plasticity are long-term potentiation (LTP) and its counterpart long-term depression (LTD) of AMPA receptor-mediated synaptic transmission. In the CA1 region of the hippocampus, it has been shown that LTP often involves a rapid increase in the unitary conductance of AMPA receptor channels. However, LTP can also occur in the absence of any alteration in AMPA receptor unitary conductance. In the present study we have used whole-cell dendritic recording, failures analysis and non-stationary fluctuation analysis to investigate the mechanism of depotentiation of LTP.     

PROMOT: A Modeling Tool for Chemical Processes

The novel process modeling tool PROMOT supports the object-oriented modeling of chemical processes for the simulation environment DIVA. In PROMOT, differential-algebraic process models can be built by aggregating structural and behavioral modeling entities that represent the topological structure or the dynamic and steady-state behavior, respectively, of the investigated chemical processes. Process models and their modeling entities may be defined either in an object-oriented modeling language or with a graphical user interface. This paper discusses the modeling concept, the modeling language, the knowledge representation aspects, and the implementation of PROMOT.     

Twisting DNA: single molecule studies

Over the past 10 years a number of new techniques have emerged that allow the manipulation of single DNA molecules and other biopolymers (RNA, proteins, etc.). These experiments have permitted the measurement of the DNA stretching and twisting elasticity and have consequently revealed the essential role played by the DNA mechanical properties in its interactions with proteins. We shall first describe the different methods used to stretch and twist single DNA molecules. We will then focus on its behaviour under torsion, especially by discussing the different methods used to estimate its torsional modulus.