The Interplay of Charge and Spin in Quantum Dots: The Ising Case

The physics of quantum dots is succinctly depicted by the {\it Universal Hamiltonian}, where only zero mode interactions are included. In the case where the latter involve charging and isotropic spin-exchange terms, this would lead to a non-Abelian action. Here we address an Ising spin-exchange interaction, which leads to an Abelian action. The analysis of this simplified yet non-trivial model shed some light on a more general case of charge and spin entanglement. We present a calculation of the tunneling density of states and of the dynamic magnetic susceptibility. Our results are amenable to experimental study and may allow for an experimental determination of the exchange interaction strength.Comment: 11 pages, 7 figure

'Russian bureaucratic ruling elite': towards a social portrait of Russia's higher bureaucracy during the first quarter of the 19th century

Der vorliegende Beitrag analysiert anhand der Personalakten der Beamten (formuliarnye spisky) die Herrschaftsstruktur im zaristischen Rußland. Die Ergebnisse revidieren ein Stereotyp der sowjetischen Geschichtsschreibung: über ein Drittel der bürokratischen Eliten besaßen keine Leibeigenen. Ein kontinuierliches Wachstum dieser Gruppe läßt sich vor allem für die zentrale Verwaltung des Landes feststellen. Dieser Befund widerlegt die These der (marxistischen) Geschichtswissenschaft, daß die reale Macht in Rußland in den Händen des feudalen Landadels gelegen hat. (pmb)'An attempt is made to study the social structure of Russia's bureaucratic ruling elite during the first quarter of the 19th century. The work is done on the basis of a mass statistic source: service records of bureaucracy (formuliarnye spisky). The results of the research undermine common stereotypes in Soviet historiography. Among the higher bureaucratic elites one third owned no serfs whatsoever. A constant growth of this group was observed, especially in the central bureaucracy. Thus, a close analysis of the data disproves the widely-held belief that real power and authority in Russia was connected with the landed gentry.' (author's abstract

U(1) and SU(2) quantum dissipative systems: The Caldeira-Leggett vs. the Amegaokar-Eckern-Sch\"on approaches

There are two paradigmatic frameworks for treating quantum systems coupled to a dissipative environment: the Caldeira-Leggett and the Ambegaokar-Eckern-Sch\"on approaches. Here we recall the differences between them, and explain the consequences when each is applied to a zero dimensional spin (possessing an SU(2) symmetry) in a dissipative environment (a dissipative quantum dot near or beyond the Stoner instability point).Comment: Contribution for Leonid Keldysh 85 Festschrif

The ozone depletion potentials on halocarbons: Their dependence of calculation assumptions

The concept of Ozone Depletion Potential (ODP) is widely used in the evaluation of numerous halocarbons and of their replacement effects on ozone, but the methods, assumptions and conditions used in ODP calculations have not been analyzed adequately. In this paper a model study of effects on ozone of the instantaneous releases of various amounts of CH3CCl3 and of CHF2Cl (HCFC-22) for several compositions of the background atmosphere are presented, aimed at understanding connections of ODP values with the assumptions used in their calculations. To facilitate the ODP computation in numerous versions for the long time periods after their releases, the above rather short-lived gases and the one-dimensional radiative photochemical model of the global annually averaged atmospheric layer up to 50 km height are used. The variation of released gas global mass from 1 Mt to 1 Gt leads to ODP value increase with its stabilization close to the upper bound of this range in the contemporary atmosphere. The same variations are analyzed for conditions of the CFC-free atmosphere of 1960's and for the anthropogenically loaded atmosphere in the 21st century according to the known IPCC 'business as usual' scenario. Recommendations for proper ways of ODP calculations are proposed for practically important cases

A Knowledge Representation Model for Massive Open Online Course Platforms

This paper describes a knowledge model for the design of Massive Open Online Course (MOOC) platforms. It is based on our generic instructional engineering method called Knowledge Field of Educational Environment with Competence Boundary Conditions (KFEEC). KFEEC uses the ontology as a foundation for the knowledge representation model. It provides a flexible structure to the various self-paced e-learning system designs but appears to be overcomplicated for the MOOC platform. This paper describes the KFEEC method, the steps of adapting the KFEEC to the MOOC platform design, and the specification of the resulting knowledge model. This model is a core of the MOOC platform that will be developed in future work

COMPARATIVE CHARACTERISTICS OF DIFFERENT SYSTEMS FOR PROVIDING TRANSOSSEOUS OSTEOSYNTHESIS IN SMALL PETS IN MODERN VETERINARY PRACTICE

The article is devoted to a general review of various systems for external osteosynthesis used in modern veterinary medicine. The aim of the study was to summarize and analyze articles on the use of various systems for external osteosynthesis used in modern veterinary medicine. The analysis of the technical base of the main components of the systems under study for external (transosseous) osteosynthesis was carried out. An assessment was made of the possibility of assembling hardware structures from the parts of the systems under study from the point of view of hardware configurations. The study found: - To ensure the functional diversity of hardware combinations, the systems studied in the work use radius components (rings and their derivatives), which originate from the rings represented in the Ilizarov system. - The presence of special clamping devices in the systems expands the clinical range of application of hardware structures for transosseous osteosynthesis. - The use of rotary mechanisms in the form of brackets (cardans, hinges) expands the technological possibilities of using external fixation devices, if spatial control of hardware structures is necessary, both during operations and in the postoperative period

Investigation of vibratory drilling model with adaptive control. Part 2: mixed control of peak-to-peak vibration displacement and cutting continuity index

Chip segmentation is important condition for deep drilling efficiency improving. Chip segmentation could be ensured by sustaining stable axial self-excited vibrations of a drill. Vibrations are excited by regenerative effect when cutting edges move along the surface formed by previous passes. The conditions required for reliable chip segmentation could be created by using of a special vibratory head with an elastic element, providing tool additional axial flexibility. To maintain stable vibro-process with amplitude sufficient for chip segmentation, it’s suggested to use the vibratory head with a special actuator for adaptive feedback control proportional to a tool vibration velocity. Two algorithms of the feedback gain adaptation are proposed in the present paper: the adaptation by peak-to-peak displacement and the mixed adaptation by peak-to-peak displacement with cutting continuity index. The investigation of effectiveness of the proposed algorithms applicable to the model, described in [9], is also presented

Protective Allele for Multiple Sclerosis HLA-DRB1*01:01 Provides Kinetic Discrimination of Myelin and Exogenous Antigenic Peptides.

Risk of the development of multiple sclerosis (MS) is known to be increased in individuals bearing distinct class II human leukocyte antigen (HLA) variants, whereas some of them may have a protective effect. Here we analyzed distribution of a highly polymorphous HLA-DRB1 locus in more than one thousand relapsing-remitting MS patients and healthy individuals of Russian ethnicity. Carriage of HLA-DRB1*15 and HLA-DRB1*03 alleles was associated with MS risk, whereas carriage of HLA-DRB1*01 and HLA-DRB1*11 was found to be protective. Analysis of genotypes revealed the compensatory effect of risk and resistance alleles in trans. We have identified previously unknown MBP153−161 peptide located at the C-terminus of MBP protein and MBP90−98 peptide that bound to recombinant HLA-DRB1*01:01 protein with affinity comparable to that of classical antigenic peptide 306-318 from the hemagglutinin (HA) of the influenza virus demonstrating the ability of HLA-DRB1*01:01 to present newly identified MBP153−161 and MBP90−98 peptides. Measurements of kinetic parameters of MBP and HA peptides binding to HLA-DRB1*01:01 catalyzed by HLA-DM revealed a significantly lower rate of CLIP exchange for MBP153−161 and MBP90−98 peptides as opposed to HA peptide. Analysis of the binding of chimeric MBP-HA peptides demonstrated that the observed difference between MBP153−161, MBP90−98, and HA peptide epitopes is caused by the lack of anchor residues in the C-terminal part of the MBP peptides resulting in a moderate occupation of P6/7 and P9 pockets of HLA-DRB1*01:01 by MBP153−161 and MBP90−98 peptides in contrast to HA308−316 peptide. This leads to the P1 and P4 docking failure and rapid peptide dissociation and release of empty HLA-DM–HLA-DR complex. We would like to propose that protective properties of the HLA-DRB1*01 allele could be directly linked to the ability of HLA-DRB1*01:01 to kinetically discriminate between antigenic exogenous peptides and endogenous MBP derived peptides