A note on finding minimum cuts in directed planar networks by parallel computations

We consider the problem of finding a maximum subset of a given set of wires connecting two rows of terminals with fixed positions, such that no wires in the subset cross. We derive an algorithm that runs in O(p + (n ? p) ? g(p + 1)) time, where n is the number of wires given and p is the maximum number of noncrossing wires; in many practically relevant cases, e.g., when p is very high, it needs only linear time. We show how an extension of the algorithm solves the more general problem, where the positions of some terminals have some flexibility, within the same time bound.     

Observation of Unconventional Dynamics of Domain Walls in Uniaxial Ferroelectric Lead Germanate

Application of scanning probe microscopy techniques such as piezoresponse force microscopy (PFM) opens the possibility to re‐visit the ferroelectrics previously studied by the macroscopic electrical testing methods and establish a link between their local nanoscale characteristics and integral response. The nanoscale PFM studies and phase field modeling of the static and dynamic behavior of the domain structure in the well‐known ferroelectric material lead germanate, Pb₅Ge₃O₁₁, are reported. Several unusual phenomena are revealed: 1) domain formation during the paraelectric‐to‐ferroelectric phase transition, which exhibits an atypical cooling rate dependence; 2) unexpected electrically induced formation of the oblate domains due to the preferential domain walls motion in the directions perpendicular to the polar axis, contrary to the typical domain growth behavior observed so far; 3) absence of the bound charges at the 180° head‐to‐head (H–H) and tail‐totail (T–T) domain walls, which typically exhibit a significant charge density in other ferroelectrics due to the polarization discontinuity. This strikingly different behavior is rationalized by the phase field modeling of the dynamics of uncharged H–H and T–T domain walls. The results provide a new insight into the emergent physics of the ferroelectric domain boundaries, revealing unusual properties not exhibited by conventional Ising‐type walls.     

Determination and correlation of axial-mixing parameters in an agitated liquid-liquid extraction column

Dispersion coefficients were measured in a pilot-plant sized agitated liquid-liquid extraction column of the Kuhni type. Available techniques were considered, and the axial mixing in both phases obtained over a broad range of operating conditions, both with and without mass transfer and with two sets of stator plates. Earlier correlations for backmixing in the continuous phase were checked and improved, the final equation being successfully tested on available published data.     

On weak completeness and weak non-degeneracy of networks

The graph-theoretic properties depending on the element types and their controllability but not on the particular form of constitutive relations of elements are considered. New concepts such as normal partition pair of the branch set, weak completeness and weak non-degeneracy are introduced and their properties are investigated in detail. These properties may then be used to formulate purely topological methods of analysing some dynamical aspects of nonlinear RLC networks.     

Telomerase Interaction Partners–Insight from Plants

Telomerase, an essential enzyme that maintains chromosome ends, is important for genome integrity and organism development. Various hypotheses have been proposed in human, ciliate and yeast systems to explain the coordination of telomerase holoenzyme assembly and the timing of telomerase performance at telomeres during DNA replication or repair. However, a general model is still unclear, especially pathways connecting telomerase with proposed non-telomeric functions. To strengthen our understanding of telomerase function during its intracellular life, we report on interactions of several groups of proteins with the Arabidopsis telomerase protein subunit (AtTERT) and/or a component of telomerase holoenzyme, POT1a protein. Among these are the nucleosome assembly proteins (NAP) and the minichromosome maintenance (MCM) system, which reveal new insights into the telomerase interaction network with links to telomere chromatin assembly and replication. A targeted investigation of 176 candidate proteins demonstrated numerous interactions with nucleolar, transport and ribosomal proteins, as well as molecular chaperones, shedding light on interactions during telomerase biogenesis. We further identified protein domains responsible for binding and analyzed the subcellular localization of these interactions. Moreover, additional interaction networks of NAP proteins and the DOMINO1 protein were identified. Our data support an image of functional telomerase contacts with multiprotein complexes including chromatin remodeling and cell differentiation pathways.     

腐植酸的体外作用

腐植酸被认为在动物喂饲试验中对健康和产率具有整体积极作用,同时颇有争议的是,其也被作为肿瘤的病原学因素之一。我们尝试评价斯洛伐克地区特定来源腐植酸在使用推荐预防剂量时的体外作用。研究其体外的抗氧化性质、对肝线粒体中酶系和非酶系抗氧化防御系统的作用以及对人工培养肿瘤细胞株的作用。我们观察到不论腐植酸是溶解于二甲基亚砜(DMSO)或是直接加入呼吸介质中线粒体悬浮液,在腐植酸给药后超氧化物歧化酶(SOD)活性显著下降。所测定的其他抗氧化酶如谷胱甘肽过氧化物酶(GPx)和谷胱甘肽还原酶(GR),其活性及还原型谷胱甘肽(GSH)的含量与对照组相比并未表现出显著变化。腐植酸对超氧阴离子自由基(O2-·)的抑制率低于其对羟自由基(·OH)的抑制率。6种不同肿瘤细胞株的存活率显示出只有急性T淋巴性白血病细胞株对测试腐植酸敏感。尽管在水溶液中溶解度相对较低,但特定来源腐植酸参与了氧化还原调控。通过夺取自由基,腐植酸重置了抗氧化防御机制。来源于自然资源的腐植酸体外研究结果显示出其作为有前景的免疫增强剂的潜力。     

Effects of composition and plastifier on the light scattering of polymer glasses and properties of polymeric optical fibers made from styrene-methyl methacrylate copolymers

High optical purity polystyrene (PS), poly(methyl methacrylate) (PMMA) and styrene-methyl methacrylate statistical copolymers (S-MMA) were prepared. Light scattering measured on polymeric glasses depends on the chemical composition of the polymer and on the refractive index of the plastifier added. An isorefractive plastifier reduces considerably the scattering values for the copolymers S-MMA, while having no significant effect on the scattering of PMMA. A plastifier with a refractive index different from that of the polymer raises distinctly the light scattering values in all cases. It has been shown that the isorefractive plastifier has a favourable effect on attenuation loss of polymeric optical fibers (POF) obtained from the copolymer S-MMA 2/1.     

Cytoprotective effect of a bilberry extract against oxidative damage of rat hepatocytes

The effect of a bilberry extract (BE, 25% anthocyanins) against oxidative damage in primary cultures of rat hepatocytes, induced by tert-butyl hydroperoxide and allyl alcohol, was investigated. BE displayed cytoprotective effects at 100 and 500 μg/ml in the MTT viability test. It protected the cells against lactate dehydrogenase leakage and lipoperoxidation products formation. Maximum protection (58%) was noted using 500 μg/ml of BE and intoxication by allyl alcohol. The observed cytoprotective effect is probably due to the antioxidant properties of its constituents, mainly anthocyanins. BE scavenged DPPH (IC₅₀ 3.99 ± 0.14 μg/ml) and enzymatically generated superoxide radical with an activity equivalent to 108 ± 7.2 U of superoxide dismutase per mg of extract. Our results support the use of bilberry and bilberry extracts in functional foods and food supplements designed for the prevention of chronic diseases associated with oxidative stress.     

Temperature fields of the extruded pipe under conditions of co-current cooling

This article examines the temperature fields of the thick wall pipe while cooling it under the process of extrusion. We solved the Fourier–Kirchhoff equation by Fourier method in the form of an infinite row and with the help of Bessel’s functions. The equations were transformed into dimensionless forms and a solution of during heat we got as the function of Biot’s and Fourier’s number, dimensionless inner radius and thermal capacitance ratio of contact phases.     

Managing the three Levels of Change

Change may be introduced into an organization a variety of ways - implementing new technology, employing new people, or in establishing new organizational structures, new policies, or new procedures. Just as change is made up of different components, it comes in varying degrees. A three-level classification of change can help IS managers gain control over the variable components and nature of change.