Inflammation and changes in cytokine levels in neurological feline infectious peritonitis.

Feline infectious peritonitis (FIP) is a progressive, fatal, predominantly Arthus-type immune-mediated disease that is triggered when cats are infected with a mutant enteric coronavirus. The disease presents variably with multiple organ failure, seizures, generalized effusion, or shock. Neurological FIP is clinically and pathologically more homogeneous than systemic 'wet' or 'dry' FIP; thus, comparison of cytokine profiles from cats with neurological FIP, wet FIP, and non-FIP neurological disease may provide insight into some baseline characteristics relating to the immunopathogenesis of neurological FIP. This study characterizes inflammation and changes in cytokines in the brain tissue of FIP-affected cats. Cellular infiltrates in cats with FIP included lymphocytes, plasma cells, neutrophils, macrophages, and eosinophils. IL-1 beta, IL-6, IL-12, IL-18, TNF-alpha, macrophage inhibitory protein (MIP)-1 alpha, and RANTES showed no upregulation in the brains of control cats, moderate upregulation in neurological FIP cats, and very high upregulation in generalized FIP cats. Transcription of IFN-gamma appeared upregulated in cats with systemic FIP and slightly downregulated in neurological FIP. In most cytokines tested, variance was extremely high in generalized FIP and much less in neurological FIP. Principal components analysis was performed in order to find the least number of 'components' that would summarize the cytokine profiles in cats with neurological FIP. A large component of the variance (91.7%) was accounted for by levels of IL-6, MIP-1 alpha, and RANTES. These findings provide new insight into the immunopathogenesis of FIP and suggest targets for immune therapy of this disease

The geochemistry of iodine and bromine in sediments of the Panama Basin

The areal and vertical distribution of iodine, bromine and organic carbon has been examined in a suite of sediment cores from the Panama Basin. Both halogens are approximately correlative with organic carbon in surface sediments. The concentrations of all three elements vary sympathetically but considerably with depth, especially in equatorial carbonate oozes where a distinct mid-depth (40-80 cm) concentration maximum is observed...

The ac-Driven Motion of Dislocations in a Weakly Damped Frenkel-Kontorova Lattice

By means of numerical simulations, we demonstrate that ac field can support stably moving collective nonlinear excitations in the form of dislocations (topological solitons, or kinks) in the Frenkel-Kontorova (FK) lattice with weak friction, which was qualitatively predicted by Bonilla and Malomed [Phys. Rev. B{\bf 43}, 11539 (1991)]. Direct generation of the moving dislocations turns out to be virtually impossible; however, they can be generated initially in the lattice subject to an auxiliary spatial modulation of the on-site potential strength. Gradually relaxing the modulation, we are able to get the stable moving dislocations in the uniform FK lattice with the periodic boundary conditions, provided that the driving frequency is close to the gap frequency of the linear excitations in the uniform lattice. The excitations have a large and noninteger index of commensurability with the lattice (suggesting that its actual value is irrational). The simulations reveal two different types of the moving dislocations: broad ones, that extend, roughly, to half the full length of the periodic lattice (in that sense, they cannot be called solitons), and localized soliton-like dislocations, that can be found in an excited state, demonstrating strong persistent internal vibrations. The minimum (threshold) amplitude of the driving force necessary to support the traveling excitation is found as a function of the friction coefficient. Its extrapolation suggests that the threshold does not vanish at the zero friction, which may be explained by radiation losses. The moving dislocation can be observed experimentally in an array of coupled small Josephson junctions in the form of an {\it inverse Josephson effect}, i.e., a dc-voltage response to the uniformly applied ac bias current.Comment: Plain Latex, 13 pages + 9 PostScript figures. to appear on Journal of Physics: condensed matte

Deformation of LeBrun's ALE metrics with negative mass

In this article we investigate deformations of a scalar-flat K\"ahler metric on the total space of complex line bundles over CP^1 constructed by C. LeBrun. In particular, we find that the metric is included in a one-dimensional family of such metrics on the four-manifold, where the complex structure in the deformation is not the standard one.Comment: 20 pages, no figure. V2: added two references, filled a gap in the proof of Theorem 1.2. V3: corrected a wrong statement about Kuranishi family of a Hirzebruch surface stated in the last paragraph in the proof of Theorem 1.2, and fixed a relevant error in the proof. Also added a reference [24] about Kuranishi family of Hirzebruch surface

A mapping approach to synchronization in the "Zajfman trap": stability conditions and the synchronization mechanism

We present a two particle model to explain the mechanism that stabilizes a bunch of positively charged ions in an "ion trap resonator" [Pedersen etal, Phys. Rev. Lett. 87 (2001) 055001]. The model decomposes the motion of the two ions into two mappings for the free motion in different parts of the trap and one for a compressing momentum kick. The ions' interaction is modelled by a time delay, which then changes the balance between adjacent momentum kicks. Through these mappings we identify the microscopic process that is responsible for synchronization and give the conditions for that regime.Comment: 12 pages, 9 figures; submitted to Phys Rev

Double solid twistor spaces: the case of arbitrary signature

In a recent paper (math.DG/0701278) we constructed a series of new Moishezon twistor spaces which is a kind of variant of the famous LeBrun twistor spaces. In this paper we explicitly give projective models of another series of Moishezon twistor spaces on nCP^2 for arbitrary n>2, which can be regarded as a generalization of the twistor spaces of a 'double solid type' on 3CP^2 studied by Kreussler, Kurke, Poon and the author. Similarly to the twistor spaces of 'double solid type' on 3CP^2, projective models of present twistor spaces have a natural structure of double covering of a CP^2-bundle over CP^1. We explicitly give a defining polynomial of the branch divisor of the double covering whose restriction to fibers are degree four. If n>3 these are new twistor spaces, to the best of the author's knowledge. We also compute the dimension of the moduli space of these twistor spaces. Differently from math.DG/0701278, the present investigation is based on analysis of pluri-(half-)anticanonical systems of the twistor spaces.Comment: 30 pages, 3 figures; v2: title changed (the original title was "Explicit construction of new Moishezon twistor spaces, II".

Comparison of Coding DNA

We discuss a model for the evolutionary distance between two coding DNA sequences which specializes to the DNA/protein model proposed in Hein [3]. We discuss the DNA/protein model in details and present a quadratic time algorithm that computes an optimal alignment of two coding DNA sequences in the model under the assumption of affine gap cost. The algorithm solves a conjecture in [3] and we believe that the constant factor of the running time is sufficiently small to make the algorithm feasible in practice

An Improved Algorithm for RNA Secondary Structure Prediction

Though not as abundant in known biological processes as proteins,RNA molecules serve as more than mere intermediaries betweenDNA and proteins, e.g. as catalytic molecules. Furthermore,RNA secondary structure prediction based on free energyrules for stacking and loop formation remains one of the few majorbreakthroughs in the field of structure prediction. We present anew method to evaluate all possible internal loops of size at mostk in an RNA sequence, s, in time O(k|s|^2); this is an improvementfrom the previously used method that uses time O(k^2|s|^2).For unlimited loop size this improves the overall complexity ofevaluating RNA secondary structures from O(|s|^4) to O(|s|^3) andthe method applies equally well to finding the optimal structureand calculating the equilibrium partition function. We use ourmethod to examine the soundness of setting k = 30, a commonlyused heuristic