329 research outputs found
Electroproduction of two light vector mesons in next-to-leading BFKL: study of systematic effects
The forward electroproduction of two light vector mesons is the first example
of a collision process between strongly interacting colorless particles for
which the amplitude can be written completely within perturbative QCD in the
Regge limit with next-to-leading accuracy. In a previous paper we have given a
numerical determination of the amplitude in the case of equal photon
virtualities by using a definite representation for the amplitude and a
definite optimization method for the perturbative series. Here we estimate the
systematic uncertainty of our previous determination, by considering a
different representation of the amplitude and different optimization methods of
the perturbative series. Moreover, we compare our result for the differential
cross section at the minimum momentum transfer with a different approach, based
on collinear kernel improvement.Comment: 17 pages, 11 figures; journal version, new figures and discussion
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Status of modern mirror studies in Novosibirsk
Mirrors have a number of advantages in comparison with the closed magnetic systems like tokamak, stellarator, etc. In principle, mirrors are very attractive from the engineering point of view, if the plasma confined in axisymmetric magnetic systems would be MHD stable. At present, the MHD stabile confinement has already been demonstrated for all axisymmetric traps designed in Novosibirsk for the value of β value as high as 0.4. Some important results were obtained recently in the GOL- 3and GDT experiments. In the paper, the status of two mirror traps in Novosibirsk is presented and description of the main experimentsis given.Відкриті магнітні пастки мають ряд переваг у порівнянні з замкнутими магнітними системами, подібними токамаку, стелларатору і т.д. У принципі, відкриті системи досить привабливі з інженерної точки зору, якщо плазма утримується в осесиметричній магнітній конфігурації, залишаючись МГД стійкої. В даний час МГД стійке утримання вже продемонстроване для осесиметричних пасток, досліджуваних у Новосибірську, аж до величини β=0.4. Важливі результати отримані недавно на установці ГОЛ-3 і в експериментах з газодинамічною пасткою ГДЛ. У даній роботі представлений стан робіт на двох магнітних пастках у Новосибірську і приведені результати основних експериментів.Открытые магнитные ловушки имеют ряд преимуществ по сравнению с замкнутыми магнитными системами, подобными токамаку, стелларатору и т.д. В принципе, открытые системы весьма Problems of Atomic Science and Technology. 2005. № 1. Series: Plasma Physics (10). P. 7-11 привлекательны с инженерной точки зрения, если плазма удерживается в осесимметричной магнитной конфигурации, оставаясь МГД устойчивой. В настоящее время МГД устойчивое удержание уже продемонстрировано для осесимметричных ловушек, исследуемых в Новосибирске, вплоть до величины β =0.4. Важные результаты получены недавно на установке ГОЛ-3 и в экспериментах с газодинамической ловушкой ГДЛ. В данной работе представлено состояние работ на двух магнитных ловушках в Новосибирске и приведены результаты основных экспериментов
The electrical properties of coating obtained by vacuum arc deposition
AbstractThis paper investigates the electrical properties of the coating based on Ti–C–B system. The coating was obtained by vacuum-arc method by spraying of multi compound cathode prepared by reactive hot pressing of Ti, carbon black and amorphous B powder mixture.The electrical conductivity of the coating was measured in temperature range of 10–320K which was about σ=4.8·103Ω−1cm−1 in the entire temperature range. The carrier concentration measured was about n=1·1022 cm−3. The charge carriers’ mobility varies between 10 and −7 and changes sign at temperature about T=225K
Correction of metabolic changes in the tissues of oral cavity of rats using a complex of drugs under the conditions of pathological factors
Hypoxia is a typical pathological process that occurs when tissues are insufficiently supplied with oxygen or when its utilization is impaired. One of the most important pathogenetic factors in the development of tissue hypoxia is the disintegration of the structure of mitochondrial membranes which occurs under the influence of various etiological factors. In children who suffered hypoxia in the antenatal period, the frequency of developmental delays is significantly increased, and the incidence of caries is also shown to increase as compared to healthy children. Based on the above, this work is relevant for modern dentistry. The work is devoted to the study of the state of the maxillofacial system and tissues of the oral cavity of rats under the influence of the complex of drugs under the conditions of intrauterine hypoxia, cariogenic diet, thyroid insufficiency and fluorine deficiency. The subjects of the study were 25 female white rats of the Wistar line of herd breeding from the vivarium of the SE “ISMFS NAMS” kept on a standard vivarium diet. The animals were divided into three groups – intact (7 rats), pathology model (8 rats), pathology model and drug complex (8 rats). Animals were removed from the experiment under thiopental anesthesia (40 mg/kg). Lower jaws and pulp were removed. As a result of the research, it was established that the proposed treatment-prophylactic complex has a pronounced caries-prophylactic and periodontoprotective effect. The caries-preventive effectiveness of the complex was due to its ability to stimulate the mineralizing function of the dental pulp, namely, to increase the activity of alkaline phosphatase of the pulp, as an indicator of the activation of osteoblasts, against the background of a decrease in the activity of acid phosphatase, a marker of osteoclasts
Primary Sequences of Protein-Like Copolymers: Levy Flight Type Long Range Correlations
We consider the statistical properties of primary sequences of two-letter HP
copolymers (H for hydrophobic and P for polar) designed to have water soluble
globular conformations with H monomers shielded from water inside the shell of
P monomers. We show, both by computer simulations and by exact analytical
calculation, that for large globules and flexible polymers such sequences
exhibit long-range correlations which can be described by Levy-flight
statistics.Comment: 4 pages, including 2 figures; several references added, some
formulations improve
Exactly soluble coherent state path integral with non-polynomial action
We present an example of an exactly soluble bosonic coherent state path integral with non-polynomial action
Axisymmetric open magnetic systems for plasma confinement
At present, three modern types of different mirror machines for plasma confinement and heating exist in Novosibirsk (Gas Dynamic Trap, -GDT, Multi-mirror, - GOL-3, Tandem Mirror, -AMBAL-M). All these systems are attractive from the engineering point of view because of very simple axisymmetric geometry of magnetic configurations. In this paper, the status of different confinement systems is presented. The experiments most crucial for the mirror concept are described such as a demonstration of different principles of suppression of electron heat conductivity (GDT, GOL-3), finding of MHD stable regimes of plasma confinement in axisymmetric geometric of magnetic field (GDT, AMBAL-M), an effective heating of dense plasma by relativistic electron beam (GOL-3), observation of radial diffusion of quiescent plasma with practically classical diffusion coefficient (AMBAL-M), etc. The main plasma parameters achieved in mentioned above systems are presented
Two-level Hamiltonian of a superconducting quantum point contact
In a superconducting quantum point contact, dynamics of the superconducting
phase is coupled to the transitions between the subgap states. We compute this
coupling and derive the two-level Hamiltonian of the contact.Comment: REVTeX, 5 pages, reference adde
Supersymmetric null-surfaces
Single trace operators with the large R-charge in supersymmetric Yang-Mills
theory correspond to the null-surfaces in . We argue that the
moduli space of the null-surfaces is the space of contours in the
super-Grassmanian parametrizing the complex -dimensional subspaces of
the complex -dimensional space. The odd coordinates on this
super-Grassmanian correspond to the fermionic degrees of freedom of the
superstring.Comment: v4: added a reference to the earlier work; corrected the formula for
the stabilizer of the BMN vacuum; added the discussion of the complex
structure of the odd coordinates in Section 3.
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