9,245 research outputs found

    A Mealy machine with polynomial growth of irrational degree

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    We consider a very simple Mealy machine (three states over a two-symbol alphabet), and derive some properties of the semigroup it generates. In particular, this is an infinite, finitely generated semigroup; we show that the growth function of its balls behaves asymptotically like n^2.4401..., where this constant is 1 + log(2)/log((1+sqrt(5))/2); that the semigroup satisfies the identity g^6=g^4; and that its lattice of two-sided ideals is a chain.Comment: 20 pages, 1 diagra

    The effects of parasitism and body length on positioning within wild fish shoals

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    The influence of body length and parasitism on the positioning behaviour of individuals in wild fish shoals was investigated by a novel means of capturing entire shoals of the banded killifish (Fundulus diaphanus, Lesueur) using a grid-net that maintained the two-dimensional positions of individuals within shoals. Fish in the front section of a shoal were larger than those in the rear. Individuals parasitized by the digenean trematode (Crassiphiala bulboglossa, Haitsma) showed a tendency to occupy the front of shoals. Parasitized fish were also found more in peripheral positions than central ones in a significant number of shoals. Shoal geometry was affected by the overall parasite prevalence of shoal members; shoals with high parasite prevalence displayed increasingly phallanx-like shoal formations, whereas shoals with low prevalence were more elliptical. There was no relationship between body length and parasite abundance or prevalence in the fish population which suggests body length and parasite status are independent predictors of positioning behaviour. Solitary individuals found outside shoals were both more likely to be parasitized and had higher parasite abundance than individuals engaged in shoaling. Differences in the shoaling behaviour of parasitized and unparasitized fish are discussed in the context of the adaptive manipulation hypothesis

    S-Track Stabilization of Heterotic de Sitter Vacua

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    We present a new mechanism, the S-Track, to stabilize the volume modulus S in heterotic M-theory flux compactifications along with the orbifold-size T besides complex structure and vector bundle moduli stabilization. The key dynamical ingredient which makes the volume modulus stabilization possible, is M5-instantons arising from M5-branes wrapping the whole Calabi-Yau slice. These are natural in heterotic M-theory where the warping shrinks the Calabi-Yau volume along S^1/Z_2. Combined with H-flux, open M2-instantons and hidden sector gaugino condensation it leads to a superpotential W which stabilizes S similar like a racetrack but without the need for multi gaugino condensation. Moreover, W contains two competing non-perturbative effects which stabilize T. We analyze the potential and superpotentials to show that it leads to heterotic de Sitter vacua with broken supersymmetry through non-vanishing F-terms.Comment: 16 pages, 2 figures; final PRD versio

    Genome-wide SNP typing of ancient DNA: Determination of hair and eye color of Bronze Age humans from their skeletal remains.

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    Objective A genome-wide high-throughput single nucleotide polymorphism (SNP) typing method was tested with respect of the applicability to ancient and degraded DNA. The results were compared to mini-sequencing data achieved through single base extension (SBE) typing. The SNPs chosen for the study allow to determine the hair colors and eye colors of humans. Material and methods The DNA samples were extracted from the skeletal remains of 59 human individuals dating back to the Late Bronze Age. The 3,000 years old bones had been discovered in the Lichtenstein Cave in Lower Saxony, Germany. The simultaneous typing of 24 SNPs for each of the ancient DNA samples was carried out using the 192.24 Dynamic Array (TM) by Fluidigm (R). Results Thirty-eight of the ancient samples (=64%) revealed full and reproducible SNP genotypes allowing hair and eye color phenotyping. In 10 samples (=17%) at least half of the SNPs were unambiguously determined, in 11 samples (=19%) the SNP typing failed. For 23 of the 59 individuals, a comparison of the SNP typing results with genotypes from an earlier performed SBE typing approach was possible. The comparison confirmed the full concordance of the results for 90% of the SNP typings. In the remaining 10% allelic dropouts were identified. Discussion The high genotyping success rate could be achieved by introducing modifications to the preamplification protocol mainly by increasing the DNA input and the amplification cycle number. The occurrence of allelic dropouts indicates that a further increase of DNA input to the preamplification step is desirable

    A lower bound on the tree-width of graphs with irrelevant vertices

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    For their famous algorithm for the disjoint paths problem, Robertson and Seymour proved that there is a function f such that if the tree-width of a graph G with k pairs of terminals is at least f (k), then G contains a solution-irrelevant vertex (Graph Minors. XXII., JCTB 2012). We give a single-exponential lower bound on f . This bound even holds for planar graphs

    The Impact of Transit Corridors on Residential Property Values

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    Most of the literature on transit corridors, such as superhighways and tunnels, focuses on the positive externality of transit access (e.g., interstate access, transit station) and fails to isolate the negative externality of the corridor itself. This empirical study examines two situations: one with both access benefits and negatives, and another without the access benefit. The findings reveal that proximity to the transit corridor alone without direct access conveys a negative impact on nearby housing values.

    Pregnancy-associated breast cancer - Special features in diagnosis and treatment

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    For obvious psychological reasons it is difficult to associate pregnancy - a life-giving period of our existence with life-threatening malignancies. Symptoms pointing to malignancy are often ignored by both patients and physicians, and this, together with the greater difficulty of diagnostic imaging, probably results in the proven delay in the detection of breast cancers during pregnancy. The diagnosis and treatment of breast cancer are becoming more and more important, as the fulfillment of the desire to have children is increasingly postponed until a later age associated with a higher risk of carcinoma, and improved cure rates of solid tumors no longer exclude subsequent pregnancies. The following article summarizes the special features of the diagnosis and primary therapy of pregnancy-associated breast cancer with particular consideration of cytostatic therapy
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