595 research outputs found

    Zero-one survival behavior of cyclically competing species

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    Coexistence of competing species is, due to unavoidable fluctuations, always transient. In this Letter, we investigate the ultimate survival probabilities characterizing different species in cyclic competition. We show that they often obey a surprisingly simple, though non-trivial behavior. Within a model where coexistence is neutrally stable, we demonstrate a robust zero-one law: When the interactions between the three species are (generically) asymmetric, the `weakest' species survives at a probability that tends to one for large population sizes, while the other two are guaranteed to extinct. We rationalize our findings from stochastic simulations by an analytic approach.Comment: 4 pages, 3 figure

    Searching for planar signatures in WMAP

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    We search for planar deviations of statistical isotropy in the Wilkinson Microwave Anisotropy Probe (WMAP) data by applying a recently introduced angular-planar statistics both to full-sky and to masked temperature maps, including in our analysis the effect of the residual foreground contamination and systematics in the foreground removing process as sources of error. We confirm earlier findings that full-sky maps exhibit anomalies at the planar (ll) and angular (\ell) scales (l,)=(2,5),(4,7),(l,\ell)=(2,5),(4,7), and (6,8)(6,8), which seem to be due to unremoved foregrounds since this features are present in the full-sky map but not in the masked maps. On the other hand, our test detects slightly anomalous results at the scales (l,)=(10,8)(l,\ell)=(10,8) and (2,9)(2,9) in the masked maps but not in the full-sky one, indicating that the foreground cleaning procedure (used to generate the full-sky map) could not only be creating false anomalies but also hiding existing ones. We also find a significant trace of an anomaly in the full-sky map at the scale (l,)=(10,5)(l,\ell)=(10,5), which is still present when we consider galactic cuts of 18.3% and 28.4%. As regards the quadrupole (=2\ell=2), we find a coherent over-modulation over the whole celestial sphere, for all full-sky and cut-sky maps. Overall, our results seem to indicate that current CMB maps derived from WMAP data do not show significant signs of anisotropies, as measured by our angular-planar estimator. However, we have detected a curious coherence of planar modulations at angular scales of the order of the galaxy's plane, which may be an indication of residual contaminations in the full- and cut-sky maps.Comment: 15 pages with pdf figure

    A preferential attachment model with random initial degrees

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    In this paper, a random graph process G(t)t1{G(t)}_{t\geq 1} is studied and its degree sequence is analyzed. Let (Wt)t1(W_t)_{t\geq 1} be an i.i.d. sequence. The graph process is defined so that, at each integer time tt, a new vertex, with WtW_t edges attached to it, is added to the graph. The new edges added at time t are then preferentially connected to older vertices, i.e., conditionally on G(t1)G(t-1), the probability that a given edge is connected to vertex i is proportional to di(t1)+δd_i(t-1)+\delta, where di(t1)d_i(t-1) is the degree of vertex ii at time t1t-1, independently of the other edges. The main result is that the asymptotical degree sequence for this process is a power law with exponent τ=min{τW,τP}\tau=\min\{\tau_{W}, \tau_{P}\}, where τW\tau_{W} is the power-law exponent of the initial degrees (Wt)t1(W_t)_{t\geq 1} and τP\tau_{P} the exponent predicted by pure preferential attachment. This result extends previous work by Cooper and Frieze, which is surveyed.Comment: In the published form of the paper, the proof of Proposition 2.1 is incomplete. This version contains the complete proo

    Composição botânica do consórcio de leguminosas herbáceas com Pennisetum glaucum.

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    O objetivo deste estudo foi avaliar a massa e proporção de quatro leguminosas em cultivo consorciado com milheto para produção de forrage

    Symposium on the Scottish labour market

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    In the post-war period, up to the late 1960s, Britain enjoyed a modicum of unemployment and government policies which were geared to producing Full Employment were considered a success. It was simple - boost demand and more people would find work. But the mid 1970s the economic regency enjoyed by those advocating demand sided policies fell into disrepute as the OPEC nations raised prices dramatically and brought in a new era of both rising prices and unemployment. The laws of economics, which previously had viewed policy decisions as the choice between lower unemployment and higher inflation were now redundant. Both unemployment and inflation were moving in the same direction. The era of stagflation had begun

    Tail probabilities of St. Petersburg sums, trimmed sums, and their limit

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    We provide exact asymptotics for the tail probabilities P{Sn,r>x}\mathbb{P} \{S_{n,r} > x\} as xx \to \infty, for fix nn, where Sn,rS_{n,r} is the rr-trimmed partial sum of i.i.d. St. Petersburg random variables. In particular, we prove that although the St. Petersburg distribution is only O-subexponential, the subexponential property almost holds. We also determine the exact tail behavior of the rr-trimmed limits.Comment: 24 pages, 2 figure

    Intercrops of grass with legumes as green manure for agroecological systems.

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    The stud article aimed to assess the accumulation and rates of nutrients in the biomass of the consortium of millet and leguminous plants for green fertilisation. The treatments were consortia of millet with four different leguminous plants: Cajanus cajan, Canavalia ensiformis, Mucuna aterrima, and Dolichos lablab. The treatments were distributed in a completely randomised design with four replications. The species of each consortium were planted in a line, at a distance of one metre apart. The aerial part of the plants was harvested after 90 days to determine the botanical composition, intercropping biomass, and the amount and accumulation of macronutrients in the biomass. The Millet mass did not differ among the consortia. However, among the legumes, M. aterrima has the highest mass (2806.31 kg/ha DM), which is reflected in the lower ratio of leguminous grasses in the millet consortium with M. aterrima (4.61). The consortia affected the rate and accumulation of P, B, and Fe. The biomass of the millet consortium with C. cajan presented the lowest rate. In addition, the accumulation of K, Mg, and Zn was low in this consortium. The biomass of millet intercrops with M. aterrima, D. lablab and C. ensiformis showed higher accumulations of K, Ca, and Mg. The highest accumulation of N was observed in the biomass of the consortium with M. aterrima (50.71 kg/ha). The rates and accumulations of Cu and Zn were higher in the consortium with M. aterrima. The consortium of millet with the leguminous plants is a sustainable alternative for fertilisation. The consortia with M. aterrima and D. lablab are the most promising ones, due to the higher proportion of plants

    A whole-genome sequence and transcriptome perspective on HER2-positive breast cancers

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    HER2-positive breast cancer has long proven to be a clinically distinct class of breast cancers for which several targeted therapies are now available. However, resistance to the treatment associated with specific gene expressions or mutations has been observed, revealing the underlying diversity of these cancers. Therefore, understanding the full extent of the HER2-positive disease heterogeneity still remains challenging. Here we carry out an in-depth genomic characterization of 64 HER2-positive breast tumour genomes that exhibit four subgroups, based on the expression data, with distinctive genomic features in terms of somatic mutations, copy-number changes or structural variations. The results suggest that, despite being clinically defined by a specific gene amplification, HER2-positive tumours melt into the whole luminal-basal breast cancer spectrum rather than standing apart. The results also lead to a refined ERBB2 amplicon of 106 kb and show that several cases of amplifications are compatible with a breakage-fusion-bridge mechanism
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