Branching Processes and Multi-Particle Production

The general theory of the branching processes is used for establishing the relation between the parameters $k$ and $\bar n$ of the negative binomial distribution. This relation gives the possibility to describe the overall data on multiplicity distributions in $pp (p\bar p)$-collisions for energies up to 900 GeV and to make several interesting predictions for higher energies. This general approach is free from ambiguities associated with the extrapolation of the parameter $k$ to unity.Comment: 13 pages, (8 figures available on request), DUKE-TH-93-5

Control landscapes for two-level open quantum systems

A quantum control landscape is defined as the physical objective as a function of the control variables. In this paper the control landscapes for two-level open quantum systems, whose evolution is described by general completely positive trace preserving maps (i.e., Kraus maps), are investigated in details. The objective function, which is the expectation value of a target system operator, is defined on the Stiefel manifold representing the space of Kraus maps. Three practically important properties of the objective function are found: (a) the absence of local maxima or minima (i.e., false traps); (b) the existence of multi-dimensional sub-manifolds of optimal solutions corresponding to the global maximum and minimum; and (c) the connectivity of each level set. All of the critical values and their associated critical sub-manifolds are explicitly found for any initial system state. Away from the absolute extrema there are no local maxima or minima, and only saddles may exist, whose number and the explicit structure of the corresponding critical sub-manifolds are determined by the initial system state. There are no saddles for pure initial states, one saddle for a completely mixed initial state, and two saddles for other initial states. In general, the landscape analysis of critical points and optimal manifolds is relevant to the problem of explaining the relative ease of obtaining good optimal control outcomes in the laboratory, even in the presence of the environment.Comment: Minor editing and some references adde

Endoprosthesis replacement at the treatment of elbow joint defects

Results of 25 total endoprosthesis operations in patients with defects of the elbow joint of various ethiology are analysed. The endoprostheses produced by Endoservis (Russia] and Coоnrad/Mоrrey Zimmer (USA] were used. The technique of operation and postoperative rehabilitation is described in the article. The estimation of results of treatment was performed by «the Estimation of surgery of an elbow» (American Shoulder and Elbow Surgeons (ASES] Assessments; Richards R.R. et al. 1994]. Radiographically the results of treatment were estimated by the method of X-ray stability of the implants by O.A. Kudinov, V.l. Nujdin. The majority of patients undergoing arthroplasty of the elbow joint for its defects were of young age (40-45 years], and that has left its mark on the technology of operation and maintenance of the patients in different periods after surgery. The analysis of results of treatmentfor 1 year until 1-15 years after the operation was carried out. Good and excellent results, were received in 68 %, satisfactory - in 30 %. The unsatisfactory result of endoprosthesis surgery took place in 8 % of operated (2 patients]. It has been established that the endoprosthesis replacement for elbow joint defects in high-tech surgery is definitely an alternative to traditional methods of treatment, and in most cases should be seen as a method of choice for treatment of this disease

Dynamics with Infinitely Many Derivatives: The Initial Value Problem

Differential equations of infinite order are an increasingly important class of equations in theoretical physics. Such equations are ubiquitous in string field theory and have recently attracted considerable interest also from cosmologists. Though these equations have been studied in the classical mathematical literature, it appears that the physics community is largely unaware of the relevant formalism. Of particular importance is the fate of the initial value problem. Under what circumstances do infinite order differential equations possess a well-defined initial value problem and how many initial data are required? In this paper we study the initial value problem for infinite order differential equations in the mathematical framework of the formal operator calculus, with analytic initial data. This formalism allows us to handle simultaneously a wide array of different nonlocal equations within a single framework and also admits a transparent physical interpretation. We show that differential equations of infinite order do not generically admit infinitely many initial data. Rather, each pole of the propagator contributes two initial data to the final solution. Though it is possible to find differential equations of infinite order which admit well-defined initial value problem with only two initial data, neither the dynamical equations of p-adic string theory nor string field theory seem to belong to this class. However, both theories can be rendered ghost-free by suitable definition of the action of the formal pseudo-differential operator. This prescription restricts the theory to frequencies within some contour in the complex plane and hence may be thought of as a sort of ultra-violet cut-off.Comment: 40 pages, no figures. Added comments concerning fractional operators and the implications of restricting the contour of integration. Typos correcte

Spatial and Spectral Coherent Control with Frequency Combs

Quantum coherent control (1-3) is a powerful tool for steering the outcome of quantum processes towards a desired final state, by accurate manipulation of quantum interference between multiple pathways. Although coherent control techniques have found applications in many fields of science (4-9), the possibilities for spatial and high-resolution frequency control have remained limited. Here, we show that the use of counter-propagating broadband pulses enables the generation of fully controlled spatial excitation patterns. This spatial control approach also provides decoherence reduction, which allows the use of the high frequency resolution of an optical frequency comb (10,11). We exploit the counter-propagating geometry to perform spatially selective excitation of individual species in a multi-component gas mixture, as well as frequency determination of hyperfine constants of atomic rubidium with unprecedented accuracy. The combination of spectral and spatial coherent control adds a new dimension to coherent control with applications in e.g nonlinear spectroscopy, microscopy and high-precision frequency metrology.Comment: 12 page

Large Nongaussianity from Nonlocal Inflation

We study the possibility of obtaining large nongaussian signatures in the Cosmic Microwave Background in a general class of single-field nonlocal hill-top inflation models. We estimate the nonlinearity parameter f_{NL} which characterizes nongaussianity in such models and show that large nongaussianity is possible. For the recently proposed p-adic inflation model we find that f_{NL} ~ 120 when the string coupling is order unity. We show that large nongaussianity is also possible in a toy model with an action similar to those which arise in string field theory.Comment: 27 pages, no figures. Added references and some clarifying remark

Роль цитокинов в патогенезе аутоиммунного диабета, вопросы иммуноинтервенции

The review devotes to studying the role of cytokines in development of autoimmune diabetes mellitus, latent autoimmune diabetes in adults included. Therapeutic approaches to prevent the loss of endogenous insulin secretion are discussed. There is review of clinical trials of immunosuppressive agents and modulators of immune tolerance in autoimmune diabetes mellitus.Рассмотрена роль цитокинов в патогенезе аутоиммунного сахарного диабета, включая латентный аутоиммунный диабет взрослых. Обсуждаются терапевтические подходы, направленные на предупреждение снижения секреции эндогенного инсулина. Приведен обзор клинических испытаний иммуносупрессивных средств и модуляторов иммунологической толерантности при аутоиммунном сахарном диабете (типа 1А)

Revisiting the optical properties of the FMO protein

We review the optical properties of the FMO complex as found by spectroscopic studies of the Qy band over the last two decades. This article emphasizes the different methods used, both experimental and theoretical, to elucidate the excitonic structure and dynamics of this pigment–protein complex

Pure Gauge Configurations and Tachyon Solutions to String Field Theories Equations of Motion

In constructions of analytical solutions to open string field theories pure gauge configurations parameterized by wedge states play an essential role. These pure gauge configurations are constructed as perturbation expansions and to guaranty that these configurations are asymptotical solutions to equations of motions one needs to study convergence of the perturbation expansions. We demonstrate that for the large parameter of the perturbation expansion these pure gauge truncated configurations give divergent contributions to the equation of motion on the subspace of the wedge states. We perform this demonstration numerically for the pure gauge configurations related to tachyon solutions for the bosonic and the NS fermionic SFT. By the numerical calculations we also show that the perturbation expansions are cured by adding extra terms. These terms are nothing but the terms necessary to make valued the Sen conjectures.Comment: 30 pages, 9 figures, references added and conclusion extende

Linear dichroism and circular dichroism in photosynthesis research

The efficiency of photosynthetic light energy conversion depends largely on the molecular architecture of the photosynthetic membranes. Linear- and circular-dichroism (LD and CD) studies have contributed significantly to our knowledge of the molecular organization of pigment systems at different levels of complexity, in pigment–protein complexes, supercomplexes, and their macroassemblies, as well as in entire membranes and membrane systems. Many examples show that LD and CD data are in good agreement with structural data; hence, these spectroscopic tools serve as the basis for linking the structure of photosynthetic pigment–protein complexes to steady-state and time-resolved spectroscopy. They are also indispensable for identifying conformations and interactions in native environments, and for monitoring reorganizations during photosynthetic functions, and are important in characterizing reconstituted and artificially constructed systems. This educational review explains, in simple terms, the basic physical principles, and theory and practice of LD and CD spectroscopies and of some related quantities in the areas of differential polarization spectroscopy and microscopy