Remarks on Category-Based Routing in Social Networks

It is well known that individuals can route messages on short paths through social networks, given only simple information about the target and using only local knowledge about the topology. Sociologists conjecture that people find routes greedily by passing the message to an acquaintance that has more in common with the target than themselves, e.g. if a dentist in Saarbr\"ucken wants to send a message to a specific lawyer in Munich, he may forward it to someone who is a lawyer and/or lives in Munich. Modelling this setting, Eppstein et al. introduced the notion of category-based routing. The goal is to assign a set of categories to each node of a graph such that greedy routing is possible. By proving bounds on the number of categories a node has to be in we can argue about the plausibility of the underlying sociological model. In this paper we substantially improve the upper bounds introduced by Eppstein et al. and prove new lower bounds.Comment: 21 page

Effects of anisotropic conduction and heat pipe interaction on minimum mass space radiators

Equations are formulated for the two dimensional, anisotropic conduction of heat in space radiator fins. The transverse temperature field was obtained by the integral method, and the axial field by numerical integration. A shape factor, defined for the axial boundary condition, simplifies the analysis and renders the results applicable to general heat pipe/conduction fin interface designs. The thermal results are summarized in terms of the fin efficiency, a radiation/axial conductance number, and a transverse conductance surface Biot number. These relations, together with those for mass distribution between fins and heat pipes, were used in predicting the minimum radiator mass for fixed thermal properties and fin efficiency. This mass is found to decrease monotonically with increasing fin conductivity. Sensitivities of the minimum mass designs to the problem parameters are determined

20 Years of Microplasma Research: A Status Report

The field of microplasmas gained recognition as a well-defined area of research and application within the larger field of plasma science and technology about 20 years ago. Since then, the activity in microplasma research and applications has continuously increased. A survey of peer reviewed papers on microplasmas published annually shows a steady increase from fewer than 20 papers in 1995 to about 75 in 2005 and more than 150 in 2014. This count excludes papers that deal exclusively with technological applications where the microplasma is used solely as a tool. This topical review aims to provide a snap shot of the current state of microplasma research and applications. Given the rapid proliferation of microplasma applications, the topical review will focus primarily on the status of microplasma science and our understanding of the physics principles that enable microplasma operation. Where appropriate, we will also address microplasma applications, however, we will limit the discussion of microplasma applications to examples where the application is closely tied to the plasma science. No attempt is made to provide a comprehensive and in-depth review of the diverse range of all microplasma applications, except for the inclusion of a few key references to recent reviews of microplasma applications

(η5-Cyclo­penta­dien­yl)(propionitrile-κN)bis­(triphenyl­phosphine-κP)ruthenium(II) trifluoro­methane­sulfonate

The title compound, [Ru(C5H5)(C3H5N)(C18H15P)2]CF3SO3, forms yellow crystals with a distinctly hemimorphic habit. It contains a half-sandwich complex of ruthenium with a three-legged piano-stool geometry, with Ru—P = 2.3585 (4) and 2.3312 (4) Å, and Ru—N = 2.0422 (15) Å as the legs. The CF3SO3 − anion is anchored in the crystal lattice by C—H⋯O and C—H⋯F hydrogen bonds, with C⋯F,O distances starting at 3.125 (2) Å

Whole animal copper flux assessed by positron emission tomography in the Long - Evans cinnamon rat - a feasibility study

Copper is an essential trace element. However, excess copper can lead to oxidation of biomolecules and cell damage and copper levels must be carefully controlled. While copper homeostasis has been studied extensively at the cellular level, short-term body copper fluxes are poorly understood. Here, we assessed for the first time the feasibility of measuring whole body copper flux by positron emission tomography, using 64Cu. A comparative approach comparing the Long - Evans cinnamon (LEC) rat to the wild type was chosen. LEC rats are an accepted model for Wilson disease, an inherited disorder of copper excretion in humans. In LEC rats as well as in Wilson patients, the copper transporting ATPase, ATP7B, is defective. This ATPase is primarily expressed in the liver and serves in copper secretion via the bile. Dysfunction of ATP7B leads to accumulation of copper in the liver. A control and an LEC rat were transgastrically injected with 10 μg of 64Cu and the copper flux followed for three hours by whole animal PET and concomitant collection of bile, as well as the analysis of tissue following tomography. As seen by PET, the administered copper was largely trapped in the stomach and the proximal intestine, and without a significant difference between control and LEC rat. Due to an insufficient dynamic range of the PET technology, copper which was systemically absorbed and primarily transported to the liver could only be followed by sampling and by β-counting. Biliary copper excretion ensued after 15 min in the control rat, but was absent in the LEC rat. Biliary excretion reached saturation one hour after copper administration. The trapping of orally administered copper in the gastrointestinal tract may be an important mechanism to prevent copper toxicity under conditions of a sudden, excessive copper load, which cannot be alleviated by increased biliary secretion. This trapping does however limit the utility of PET to measure whole animal copper flu

Coupling of adenovirus to transferrin-polylysine/DNA complexes greatly enhances receptor-mediated gene delivery and expression of transfected genes.

We are developing efficient methods for gene transfer into tissue culture cells. We have previously shown that coupling of a chimeric adenovirus with polylysine allowed the construction of an adenovirus-polylysine-reporter-gene complex that transferred the transporter gene with great efficiency into HeLa cells. We have now explored simpler, biochemical means for coupling adenovirus to DNA/polylysine complexes and show that such complexes yield virtually 100% transfection in tissue culture cell lines. In these methods adenovirus is coupled to polylysine, either enzymatically through the action of transglutaminase or biochemically by biotinylating adenovirus and streptavidinylating the polylysine moiety. Combination complexes containing DNA, adenovirus-polylysine, and transferrin-polylysine have the capacity to transfer the reporter gene into adenovirus-receptor- and/or transferrin-receptor-rich cells