96,449 research outputs found

    2-Vertex Connectivity in Directed Graphs

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    We complement our study of 2-connectivity in directed graphs, by considering the computation of the following 2-vertex-connectivity relations: We say that two vertices v and w are 2-vertex-connected if there are two internally vertex-disjoint paths from v to w and two internally vertex-disjoint paths from w to v. We also say that v and w are vertex-resilient if the removal of any vertex different from v and w leaves v and w in the same strongly connected component. We show how to compute the above relations in linear time so that we can report in constant time if two vertices are 2-vertex-connected or if they are vertex-resilient. We also show how to compute in linear time a sparse certificate for these relations, i.e., a subgraph of the input graph that has O(n) edges and maintains the same 2-vertex-connectivity and vertex-resilience relations as the input graph, where n is the number of vertices.Comment: arXiv admin note: substantial text overlap with arXiv:1407.304

    Uterine adenocarcinoma with abdominal metastases in an ovariohysterectomised female cat

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    An adenocarcinoma of the uterine stump with abdominal metastases is described in a 12-year-old incompletely ovariohysterectomised female Domestic Short Haired (DSH) cat. At the time of presentation the adenocarcinoma had metastasised to the right peri-renal lymph node, the abdominal aorta, and the right ureter, resulting in the formation of a large cystic structure. This had compressed and displaced surrounding structures including the abdominal vena cava and the right kidney, and formed multiple adhesions to the body wall and adjacent abdominal structures. Metastatic extension to the aorta had resulted in its regression into a 2mm diameter non-pulsatile vessel

    Semi-dynamic connectivity in the plane

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    Motivated by a path planning problem we consider the following procedure. Assume that we have two points ss and tt in the plane and take K=\mathcal{K}=\emptyset. At each step we add to K\mathcal{K} a compact convex set that does not contain ss nor tt. The procedure terminates when the sets in K\mathcal{K} separate ss and tt. We show how to add one set to K\mathcal{K} in O(1+kα(n))O(1+k\alpha(n)) amortized time plus the time needed to find all sets of K\mathcal{K} intersecting the newly added set, where nn is the cardinality of K\mathcal{K}, kk is the number of sets in K\mathcal{K} intersecting the newly added set, and α()\alpha(\cdot) is the inverse of the Ackermann function

    Radio Spectra and NVSS Maps of Decametric Sources

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    We constructed radio spectra for ~1400 UTR-2 sources and find that 46% of them have concave curvature. Inspection of NVSS maps of 700 UTR sources suggests that half of all UTR sources are either blends of two or more sources or have an ultra-steep spectrum (USS). The fraction of compact USS sources in UTR may be near 10%. Using NVSS and the Digitized Sky Survey(s) we expect to double the UTR optical identification rate from currently ~19%.Comment: 2 pages, no figures; to appear in Proc. "Observational Cosmology with the New Radio Surveys", eds. M. Bremer, N. Jackson & I. Perez-Fournon, Kluwer Acad. Pres

    Tabulations of static pressure coefficients on the surfaces of 3 pylon-mounted axisymmetric flow-through nacelles at Mach numbers from 0.40 to 0.98

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    Three flow through nacelles mounted on an 82 deg swept pylon (10 percent thickness-to-chord ratio) were tested in the Langley 16 foot Transonic Tunnel. The long uncambered pylon was supported from a small body of revolution so that pressure measurements on the nacelle and pylon represent a pylon nacelle flow field without a wing present. Two nacelles had NACA 1-85-100 inlets and different circular arc afterbodies. The third nacelle had an NACA 1-70-100 inlet with a circular arc afterbody having the same external shape as one of the other nacelles. Nacelle length to maximum diameter ratio was 3.5. Data were obtained at angles of attack from 2 deg to 8 deg at selected Mach numbers

    The androgen receptor and signal-transduction pathways in hormone-refractory prostate cancer. Part 1: modifications to the androgen receptor

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    Prostate cancer is the second most common male malignancy in the western world an increasing incidence in an ageing population. Treatment of advanced prostate cancer relies on androgen deprivation. Although the majority of patients initially respond favourably to androgen deprivation therapy, the mean time to relapse is 12-18 months. Currently there are few treatments available for men who have developed resistance to hormone therapy, due to the lack of understanding of the molecular mechanisms underlying development of this disease. Recently, however, major advances have been made in understanding both androgen receptor (AR) dependent and independent pathways which promote development of hormone resistant prostate cancer. This review will focus on modifications to the AR and associated pathways. Molecular modifications to the androgen receptor itself, e.g. mutations and/or amplification, although involved in the development of hormone resistance cannot explain all cases. Phosphorylation of AR, via either Ras/MAP kinase or PI3K/Akt signal transduction pathways, have been shown to activate AR in both a ligand (androgen) dependent and independent fashion. During this review we will discuss the clinical evidence to support AR dependent pathways as mediators of hormone resistance

    Livelihood Diversification In Coastal and Inland Fishing Communities: Misconceptions, Evidence and Implications for Fisheries Management

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    This is the working paper regarding the Sustainable Fisheries Livelihoods Programme (SFLP). Diversification is a process by which households engage in multiple income generating activities. It is widely seen in the academic literature and international development arena as a strategy for spreading risk and reducing vulnerability. The formulation of policies promoting diversification is thus encouraged at national levels to alleviate poverty. However, such policies involve delicate choices and trade-offs between government objectives of development, e.g. intensification of agriculture and increase in agricultural outputs to satisfy export markets, versus increased household well-being and resilience to adversity through the promotion of small-scale, household-based, activities. In the context of fisheries, diversification is promoted as a means for reducing dependence on the resource, making restrictive management easier and less controversial for those affected by such measures. This often interprets diversification as job-substitution (stop fishing, do something else) rather than adding other activities to an income-portfolio. With the tendency for increasing pressure on fishery resources, it becomes ever more necessary to address in a coherent way diversification and its links with both poverty reduction and responsible fisheries. Implications of the development of alternative or complementary activities alongside a main, resource-dependent activity such as fishing, may echo those experienced by sectors such as agriculture and pastoralism. However, many characteristics of the fishing activity and of those who engage in it are particular to the sector. General poverty alleviation policies and fisheries management schemes have been found to lack the necessary differentiation and to fail to cater for the specific needs of fishing communities (Smith et al. 2005). The lack of attention -- or misplaced attention through maladapted policies -- that the sector and the communities it supports have received so far can be traced to a number of misconceptions stemming from "the old paradigm on poverty in small-scale fisheries" (Béné, 2003, p950). These assumptions include that (after Béné 2003, Allison and Ellis 2001): -- Fishing is an ingrained activity in fishing communities and fishermen will not leave fishing for cultural reasons. -- Fishermen are specialised and carry out fishing on a professional basis only. -- Fishing is a last resort activity and fishermen are unable to diversify into other income-generating activities. -- Fisheries development and development of fishing communities is not possible without increasing fishing effort. -- Livelihood diversification in fishing communities cannot go hand in hand with a sustainable natural resources management that encompasses both sustainable fisheries management and poverty alleviation. It is the aim of this paper to challenge these assumptions. Because of its linkages with resource management, looking at diversification in fishing communities involves re-exploring the issue from a different perspective than its current interpretation and most widely-encountered application to agricultural (land-based)-livelihoods. Despite the potential broad remit of this task, the objective here is to remain focused on the necessity to dispel misconceptions and show the need to formulate policies that support the engagement of fisherfolk and their families in multiple activities. By doing so, the paper shall also provide a compilation and review of available information related to diversification in fishing communities and point out the complexity of the issue of diversification in these communities. The geographical scope of the paper is global, guided by the availability of case study material, though reference to the West African experiences of the Sustainable Fisheries Livelihoods Programme (SFLP) is made wherever possible. Unless expressed otherwise, the terms 'fisheries' or 'fishers' make implicit reference to artisanal fisheries and the small-scale operations and modus operandi of those relying on them

    Space-efficient Feature Maps for String Alignment Kernels

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    String kernels are attractive data analysis tools for analyzing string data. Among them, alignment kernels are known for their high prediction accuracies in string classifications when tested in combination with SVM in various applications. However, alignment kernels have a crucial drawback in that they scale poorly due to their quadratic computation complexity in the number of input strings, which limits large-scale applications in practice. We address this need by presenting the first approximation for string alignment kernels, which we call space-efficient feature maps for edit distance with moves (SFMEDM), by leveraging a metric embedding named edit sensitive parsing (ESP) and feature maps (FMs) of random Fourier features (RFFs) for large-scale string analyses. The original FMs for RFFs consume a huge amount of memory proportional to the dimension d of input vectors and the dimension D of output vectors, which prohibits its large-scale applications. We present novel space-efficient feature maps (SFMs) of RFFs for a space reduction from O(dD) of the original FMs to O(d) of SFMs with a theoretical guarantee with respect to concentration bounds. We experimentally test SFMEDM on its ability to learn SVM for large-scale string classifications with various massive string data, and we demonstrate the superior performance of SFMEDM with respect to prediction accuracy, scalability and computation efficiency.Comment: Full version for ICDM'19 pape

    Clostridium difficile colitis in patients after kidney and pancreas-kidney transplantation

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    Limited data exist about Clostridium difficile colitis (CDC) in solid organ transplant patients. Between 1/1/99 and 12/31/02, 600 kidney and 102 pancreas–kidney allograft recipients were transplanted. Thirty-nine (5.5%) of these patients had CDC on the basis of clinical and laboratory findings. Of these 39 patients, 35 have information available for review. CDC developed at a median of 30 days after transplantation, and the patients undergoing pancreas–kidney transplantation had a slightly higher incidence of CDC than recipients of kidney alone (7.8% vs. 4.5%, P> 0.05). All but one patient presented with diarrhea. Twenty-four patients (64.9%) were diagnosed in the hospital, and CDC occurred during first hospitalization in 14 patients (40%). Treatment was with oral metronidazole (M) in 33 patients (94%)and M + oral vancomycin (M + V) in 2 patients. Eight patients had recurrent CDC, which occurred at a median of 30 days (range 15–314) after the first episode. Two patients (5.7%) developed fulminant CDC, presented with toxic megacolon, and underwent colectomy. One of them died; the other patient survived after colectomy. CDC should be considered as a diagnosis in transplant patients with history of diarrhea after antibiotic use, and should be treated aggressively before the infection becomes complicated

    Finding 2-Edge and 2-Vertex Strongly Connected Components in Quadratic Time

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    We present faster algorithms for computing the 2-edge and 2-vertex strongly connected components of a directed graph, which are straightforward generalizations of strongly connected components. While in undirected graphs the 2-edge and 2-vertex connected components can be found in linear time, in directed graphs only rather simple O(mn)O(m n)-time algorithms were known. We use a hierarchical sparsification technique to obtain algorithms that run in time O(n2)O(n^2). For 2-edge strongly connected components our algorithm gives the first running time improvement in 20 years. Additionally we present an O(m2/logn)O(m^2 / \log{n})-time algorithm for 2-edge strongly connected components, and thus improve over the O(mn)O(m n) running time also when m=O(n)m = O(n). Our approach extends to k-edge and k-vertex strongly connected components for any constant k with a running time of O(n2log2n)O(n^2 \log^2 n) for edges and O(n3)O(n^3) for vertices
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