Distance and the pattern of intra-European trade

Given an undirected graph G = (V, E) and subset of terminals T ⊆ V, the element-connectivity κ ′ G (u, v) of two terminals u, v ∈ T is the maximum number of u-v paths that are pairwise disjoint in both edges and non-terminals V \ T (the paths need not be disjoint in terminals). Element-connectivity is more general than edge-connectivity and less general than vertex-connectivity. Hind and Oellermann [21] gave a graph reduction step that preserves the global element-connectivity of the graph. We show that this step also preserves local connectivity, that is, all the pairwise element-connectivities of the terminals. We give two applications of this reduction step to connectivity and network design problems. • Given a graph G and disjoint terminal sets T1, T2,..., Tm, we seek a maximum number of elementdisjoint Steiner forests where each forest connects each Ti. We prove that if each Ti is k element k connected then there exist Ω( log hlog m) element-disjoint Steiner forests, where h = | i Ti|. If G is planar (or more generally, has fixed genus), we show that there exist Ω(k) Steiner forests. Our proofs are constructive, giving poly-time algorithms to find these forests; these are the first non-trivial algorithms for packing element-disjoint Steiner Forests. • We give a very short and intuitive proof of a spider-decomposition theorem of Chuzhoy and Khanna [12] in the context of the single-sink k-vertex-connectivity problem; this yields a simple and alternative analysis of an O(k log n) approximation. Our results highlight the effectiveness of the element-connectivity reduction step; we believe it will find more applications in the future

An Optical and Infrared Time-Domain Study of the Supergiant Fast X-ray Transient Candidate IC 10 X-2

We present an optical and infrared (IR) study of IC 10 X-2, a high-mass X-ray binary in the galaxy IC 10. Previous optical and X-ray studies suggest X-2 is a Supergiant Fast X-ray Transient: a large-amplitude (factor of $\sim$ 100), short-duration (hours to weeks) X-ray outburst on 2010 May 21. We analyze R- and g-band light curves of X-2 from the intermediate Palomar Transient Factory taken between 2013 July 15 and 2017 Feb 14 show high-amplitude ($\gtrsim$ 1 mag), short-duration ($\lesssim8$ d) flares and dips ($\gtrsim$ 0.5 mag). Near-IR spectroscopy of X-2 from Palomar/TripleSpec show He I, Paschen-$\gamma$, and Paschen-$\beta$ emission lines with similar shapes and amplitudes as those of luminous blue variables (LBVs) and LBV candidates (LBVc). Mid-IR colors and magnitudes from Spitzer/IRAC photometry of X-2 resemble those of known LBV/LBVcs. We suggest that the stellar companion in X-2 is an LBV/LBVc and discuss possible origins of the optical flares. Dips in the optical light curve are indicative of eclipses from optically thick clumps formed in the winds of the stellar counterpart. Given the constraints on the flare duration ($0.02 - 0.8$ d) and the time between flares ($15.1\pm7.8$ d), we estimate the clump volume filling factor in the stellar winds, $f_V$, to be $0.01 < f_V < 0.71$, which overlaps with values measured from massive star winds. In X-2, we interpret the origin of the optical flares as the accretion of clumps formed in the winds of an LBV/LBVc onto the compact object.Comment: 15 pages, 4 figures. Submitted to ApJ on Sep 26 201

Induced pluripotent stem (iPS) cells: an up-to-the-minute review

Recent advances in nuclear reprogramming technology allow the transformation of terminally differentiated, adult cells into induced pluripotent stem cells whose phenotype is indistinguishable from that of embryonic stem cells. This leap forward enables the creation of patient-specific pluripotent cell lines that carry disease genotypes. These cell lines could be used both as in vitro models for the study of disease and as potential sources of material for cell replacement therapy. Ultimately, a greater understanding of the process by which cellular identity is shaped and altered may allow the generation of particular cell types for the treatment of degenerative disease

Monte Carlo Procedure for Protein Design

A new method for sequence optimization in protein models is presented. The approach, which has inherited its basic philosophy from recent work by Deutsch and Kurosky [Phys. Rev. Lett. 76, 323 (1996)] by maximizing conditional probabilities rather than minimizing energy functions, is based upon a novel and very efficient multisequence Monte Carlo scheme. By construction, the method ensures that the designed sequences represent good folders thermodynamically. A bootstrap procedure for the sequence space search is devised making very large chains feasible. The algorithm is successfully explored on the two-dimensional HP model with chain lengths N=16, 18 and 32.Comment: 7 pages LaTeX, 4 Postscript figures; minor change

Mantenimiento basado en toma de decisiones multicriterio para incrementar disponibilidad de equipos industriales en empresa de servicios alimentarios

La presente investigación tuvo como objetivo evaluar la implementación de mantenimiento basado en toma de decisiones multicriterio para incrementar la disponibilidad de equipos industriales en una empresa de servicios alimentarios de la empresa Cordón Blue. Para lograr dicho objetivo se realizó un estudio cuantitativo del tipo aplicada, diseño preexperimental longitudinal y de alcance correlacional causal. La población estudiada, conformada por 8 equipos industriales, la muestra fue de 2 equipos y unidad de análisis 1 equipo en base al equipo de mayor criticidad por parada no planeada, cuya disponibilidad era del 92%. Se determino con las fallas del activo una estrategia de análisis con la toma de decisiones multicriterio, basándose en los métodos de árbol de decisiones y el método de suma ponderada, para generar la implementación de un plan de mantenimiento preventivo, por consecuencia del incremento de la disponibilidad al 97% se evaluó el costo beneficio de implementar el plan el cual dio un resultado favorable de 18.14. Se concluyo que al aplicar la toma de decisiones multicriterio nos permitió la decisión para implementar el plan de mantenimiento, resultando en el incremento de la disponibilidad del equip