Spline Intersection Improvement

Rendering and simulation software needs many models of reality. Every human has hair and we need to visualize realistic hair. We can model hair with many spline curves. A typical task of the ray tracing method is finding an intersection of spline curves with a ray. We try to find a fast way to calculate the point where the ray intersects the curve

Adsorption of a random heteropolymer at a potential well revisited: location of transition point and design of sequences

The adsorption of an ideal heteropolymer loop at a potential point well is investigated within the frameworks of a standard random matrix theory. On the basis of semi-analytical/semi-numerical approach the histogram of transition points for the ensemble of quenched heteropolymer structures with bimodal symmetric distribution of types of chain's links is constructed. It is shown that the sequences having the transition points in the tail of the histogram display the correlations between nearest-neighbor monomers.Comment: 11 pages (revtex), 3 figure

Generalized Smoluchowski equation with correlation between clusters

In this paper we compute new reaction rates of the Smoluchowski equation which takes into account correlations. The new rate K = KMF + KC is the sum of two terms. The first term is the known Smoluchowski rate with the mean-field approximation. The second takes into account a correlation between clusters. For this purpose we introduce the average path of a cluster. We relate the length of this path to the reaction rate of the Smoluchowski equation. We solve the implicit dependence between the average path and the density of clusters. We show that this correlation length is the same for all clusters. Our result depends strongly on the spatial dimension d. The mean-field term KMFi,j = (Di + Dj)(rj + ri)d-2, which vanishes for d = 1 and is valid up to logarithmic correction for d = 2, is the usual rate found with the Smoluchowski model without correlation (where ri is the radius and Di is the diffusion constant of the cluster). We compute a new rate: the correlation rate K_{i,j}^{C} (D_i+D_j)(r_j+r_i)^{d-1}M{\big(\frac{d-1}{d_f}}\big) is valid for d \leq 1(where M(\alpha) = \sum+\infty i=1i\alphaNi is the moment of the density of clusters and df is the fractal dimension of the cluster). The result is valid for a large class of diffusion processes and mass radius relations. This approach confirms some analytical solutions in d 1 found with other methods. We also show Monte Carlo simulations which illustrate some exact new solvable models

Shot Noise in Mesoscopic Diffusive Andreev Wires

We study shot noise in mesoscopic diffusive wires between a normal and a superconducting terminal. We particularly focus on the regime, in which the proximity-induced reentrance effect is important. We will examine the difference between a simple Boltzmann-Langevin description, which neglects induced correlations beyond the simple conductivity correction, and a full quantum calculation. In the latter approach, it turns out that two Andreev pairs propagating coherently into the normal metal are anti-correlated for E<E_c, where E_c=D/L^2 is the Thouless energy. In a fork geometry the flux-sensitive suppression of the effective charge was confirmed experimentally.Comment: 12 pages, proceedings of the NATO ARW MQO, Bled, Sloveni

Energy dependent counting statistics in diffusive superconducting tunnel junctions

We present an investigation of the energy dependence of the full charge counting statistics in diffusive normal-insulating-normal-insulating-superconducting junctions. It is found that the current in general is transported via a correlated transfer of pairs of electrons. Only in the case of strongly asymmetric tunnel barriers or energies much larger than the Thouless energy is the pair transfer uncorrelated. The second cumulant, the noise, is found to depend strongly on the applied voltage and temperature. For a junction resistance dominated by the tunnel barrier to the normal reservoir, the differential shot noise shows a double peak feature at voltages of the order of the Thouless energy, a signature of an ensemble averaged electron-hole resonance.Comment: 8 pages, 5 figure

Получение солей основных аминокислот с ацетилсалициловой и кетоглутаровой кислотами

Methods of preparation, physical and chemical characteristics for amine salts of basic amino acids (L-arginine, L and DL-lysine, L-ornitine) with acetylsalicylic and ketoglutaric acids, as well as ketoglutaric acid double salts containing L-glutamine as the second cation, have been described. The obtained salts of amino acids are potentially therapeutically important compounds.Описано получение и физико-химические характеристики аминовых солей оснóвных аминокислот (L-аргинина, L- и DL-лизина, L-орнитина) с ацетилсалициловой и кетоглутаровой кислотами, а также двойных солей кетоглутаровой кислоты, содержащих в качестве второго катиона L-глутамин. Соли полученных оснóвных аминокислот являются потенциально терапевтически значимыми соединениями

Препаративный синтез N-ацетил-3-индолинонов

Compounds that contain an indole cycle in their structure have biological activity and are a source for the development of new medicinal products. N-acetyl-3-indolinones are actively used as incoming substance for their organic synthesis. Preparative methods for the obtaining of N-acetyl-3-indolinones, used as incoming substances for the synthesis of condensed indole derivatives with high therapeutic activity, have been developed. Synthesis of N-acetyl-3-indolinone was performed by deacetylation and cyclization of N-(2-carboxyphenyl) glycine and its 4-bromo-derivative to form N,O-diacetylindoxyls followed by hydrolysis of the obtained compounds to target indolinones. It was established that brominated derivatives have increased stability as compared with the analogues which do not contain bromine on the benzene ring of the indole nucleus, resulting in the increase in the yield of desired products in the reaction.Соединения, содержащие в своей структуре индольный цикл, обладают биологической активностью и являются источником для разработки новых лекарственных средств. Для их органического синтеза активно используются в качестве исходных веществ N-ацетил-3-индолиноны. Разработаны препаративные методики получения N-ацетил-3-индолинонов, применяемых в качестве исходных соединений для синтеза конденсированных производных индола, обладающих высокой терапевтической активностью. Синтез N-ацетил-3-индолинонов осуществляли путем диацетилирования и циклизации N-(2-карбоксифенил)глицина и его 4-бромпроизводного с образованием N,O-диацетилиндоксилов с последующим гидролизом полученных соединений до целевых индолинонов. Установлено, что бромзамещенные производные обладают повышенной стабильностью по сравнению с аналогами, не содержащими брома в бензольном кольце индольного ядра, в результате чего при их использовании в реакции повышается выход целевых продуктов

Синтез ацильных производных тиазоло[5,4-b]индола.

2-Amino-4-acetylthiazolo[5,4-b]indole and its bromosubstituted analogue contain a free amino group and are initial compounds for chemical modification in order to obtain on their basis functional derivatives having high therapeutic activity. By the interaction of these 2-aminо-4-acetylthiazolo[5,4-b]indoles with succinic and maleic anhydrides, the corresponding imides and amides were obtained, which are of interest for use in order to create on their basis antihypoxic and actoprotective agents.2-амино-4-ацетилтиазоло[5,4-b]индол и его 7-бромзамещенный аналог содержат свободную аминогруппу и являются исходными соединениями для химической модификации с целью получения на их основе ряд функциональных производных, обладающих терапевтической активностью. Взаимодействием указанных 2-аминотиазоло[5,4-b]индолов с янтарным и малеиновым ангидридами были получены соответствующие имидои амидопроизводные, представляющие интерес для создания на их основе лекарственных средств антигипоксического и актопротекторного действия