Gravity of Monopole and String and Gravitational Constant in 3He-A

We discuss the effective metric produced in superfluid 3He-A by such topological objects as radial disgyration and monopole. In relativistic theories these metrics are similar to that of the local string and global monopole correspondingly. But in 3He-A they have the negative angle deficit, which corresponds to the negative mass of the topological objects. The effective gravitational constant G in superfluid 3He-A, derived from the comparison with relativistic theories, is inversely proportional to the square of the gap amplitude Delta, which plays the part of the Planck energy cut-off. G depends on temperature and increases with T, which corresponds to the vacuum screening of the Newton's constant.Comment: Latex file, 10 pages, no figure

Grain Boundary Scars and Spherical Crystallography

We describe experimental investigations of the structure of two-dimensional spherical crystals. The crystals, formed by beads self-assembled on water droplets in oil, serve as model systems for exploring very general theories about the minimum energy configurations of particles with arbitrary repulsive interactions on curved surfaces. Above a critical system size we find that crystals develop distinctive high-angle grain boundaries, or scars, not found in planar crystals. The number of excess defects in a scar is shown to grow linearly with the dimensionless system size. The observed slope is expected to be universal, independent of the microscopic potential.Comment: 4 pages, 3 eps figs (high quality images available from Mark Bowick

Identifizierung VHL-assoziierter Veränderungen im klarzelligen Nierenzellkarzinom: Anwendung von kombinierten Genom- und Expressionsanalysen

Zusammenfassung: Das sporadische Nierenzellkarzinom (NZK) ist ein heterogener solider Tumor, der traditionell basierend auf morphologischen Kriterien in weitere Subtypen unterteilt wird. In den letzten Jahren konnten unter Anwendung molekularer Hochdurchsatzanalysen genetische, transkriptionelle und translationale Alterationen identifiziert werden. Diese Marker eignen sich zum einen für die molekulare Klassifizierung des NZK und haben zum anderen prognostische Wertigkeit. Die isolierte Betrachtung genetischer, transkriptioneller und translationaler Veränderungen verhindert jedoch ein tieferes Verständnis für die komplexen Vorgänge der Karzinogenese. Wir fassen hier aktuelle Forschungsergebnisse zur molekularen Charakterisierung des NZK zusammen und stellen ein systembiologisches Konzept zur Identifizierung neuer Tumormarker vor. Diese könnten zukünftig Einsatz in der Diagnostik und Therapie des sporadischen NZK finde

Force-extension relation of cross-linked anisotropic polymer networks

Cross-linked polymer networks with orientational order constitute a wide class of soft materials and are relevant to biological systems (e.g., F-actin bundles). We analytically study the nonlinear force-extension relation of an array of parallel-aligned, strongly stretched semiflexible polymers with random cross-links. In the strong stretching limit, the effect of the cross-links is purely entropic, independent of the bending rigidity of the chains. Cross-links enhance the differential stretching stiffness of the bundle. For hard cross-links, the cross-link contribution to the force-extension relation scales inversely proportional to the force. Its dependence on the cross-link density, close to the gelation transition, is the same as that of the shear modulus. The qualitative behavior is captured by a toy model of two chains with a single cross-link in the middle.Comment: 7 pages, 4 figure

Facet Formation in the Negative Quenched Kardar-Parisi-Zhang Equation

The quenched Kardar-Parisi-Zhang (QKPZ) equation with negative non-linear term shows a first order pinning-depinning (PD) transition as the driving force $F$ is varied. We study the substrate-tilt dependence of the dynamic transition properties in 1+1 dimensions. At the PD transition, the pinned surfaces form a facet with a characteristic slope $s_c$ as long as the substrate-tilt $m$ is less than $s_c$. When $m<s_c$, the transition is discontinuous and the critical value of the driving force $F_c(m)$ is independent of $m$, while the transition is continuous and $F_c(m)$ increases with $m$ when $m>s_c$. We explain these features from a pinning mechanism involving a localized pinning center and the self-organized facet formation.Comment: 4 pages, source TeX file and 7 PS figures are tarred and compressed via uufile

Generalized Dynamic Scaling for Critical Magnetic Systems

The short-time behaviour of the critical dynamics for magnetic systems is investigated with Monte Carlo methods. Without losing the generality, we consider the relaxation process for the two dimensional Ising and Potts model starting from an initial state with very high temperature and arbitrary magnetization. We confirm the generalized scaling form and observe that the critical characteristic functions of the initial magnetization for the Ising and the Potts model are quite different.Comment: 32 pages with15 eps-figure

The cohesin ring concatenates sister DNA molecules

Sister chromatid cohesion, which is essential for mitosis, is mediated by a multi-subunit protein complex called cohesin whose Scc1, Smc1, and Smc3 subunits form a tripartite ring structure. It has been proposed that cohesin holds sister DNAs together by trapping them inside its ring. To test this, we used site-specific cross-linking to create chemical connections at the three interfaces between the ring’s three constituent polypeptides, thereby creating covalently closed cohesin rings. As predicted by the ring entrapment model, this procedure produces dimeric DNA/cohesin structures that are resistant to protein denaturation. We conclude that cohesin rings concatenate individual sister minichromosome DNAs

Marburg hemorrhagic fever in Durba and Watsa, Democratic Republic of the Congo: clinical documentation, features of illness, and treatment

The objective of the present study was to describe day of onset and duration of symptoms of Marburg hemorrhagic fever (MHF), to summarize the treatments applied, and to assess the quality of clinical documentation. Surveillance and clinical records of 77 patients with MHF cases were reviewed. Initial symptoms included fever, headache, general pain, nausea, vomiting, and anorexia (median day of onset, day 1-2), followed by hemorrhagic manifestations (day 5-8+), and terminal symptoms included confusion, agitation, coma, anuria, and shock. Treatment in isolation wards was acceptable, but the quality of clinical documentation was unsatisfactory. Improved clinical documentation is necessary for a basic evaluation of supportive treatment

Crossover from Isotropic to Directed Percolation

Percolation clusters are probably the simplest example for scale--invariant structures which either are governed by isotropic scaling--laws (``self--similarity'') or --- as in the case of directed percolation --- may display anisotropic scaling behavior (``self--affinity''). Taking advantage of the fact that both isotropic and directed bond percolation (with one preferred direction) may be mapped onto corresponding variants of (Reggeon) field theory, we discuss the crossover between self--similar and self--affine scaling. This has been a long--standing and yet unsolved problem because it is accompanied by different upper critical dimensions: $d_c^{\rm I} = 6$ for isotropic, and $d_c^{\rm D} = 5$ for directed percolation, respectively. Using a generalized subtraction scheme we show that this crossover may nevertheless be treated consistently within the framework of renormalization group theory. We identify the corresponding crossover exponent, and calculate effective exponents for different length scales and the pair correlation function to one--loop order. Thus we are able to predict at which characteristic anisotropy scale the crossover should occur. The results are subject to direct tests by both computer simulations and experiment. We emphasize the broad range of applicability of the proposed method.Comment: 19 pages, written in RevTeX, 12 figures available upon request (from [email protected] or [email protected]), EF/UCT--94/2, to be published in Phys. Rev. E (May 1994

Kinetic Theory of Flux Line Hydrodynamics:LIQUID Phase with Disorder

We study the Langevin dynamics of flux lines of high--T$_c$ superconductors in the presence of random quenched pinning. The hydrodynamic theory for the densities is derived by starting with the microscopic model for the flux-line liquid. The dynamic functional is expressed as an expansion in the dynamic order parameter and the corresponding response field. We treat the model within the Gaussian approximation and calculate the dynamic structure function in the presence of pinning disorder. The disorder leads to an additive static peak proportional to the disorder strength. On length scales larger than the line static transverse wandering length and at long times, we recover the hydrodynamic results of simple frictional diffusion, with interactions additively renormalizing the relaxational rate. On shorter length and time scales line internal degrees of freedom significantly modify the dynamics by generating wavevector-dependent corrections to the density relaxation rate.Comment: 61 pages and 6 figures available upon request, plain TEX using Harvard macro