773 research outputs found

    How Does Restored Habitat For Chinook Salmon ( Oncorhynchus Tshawytscha ) In The Merced River In California Compare With Other Chinook Streams?

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    The amount of time and money spent on restoring rivers for declining populations of salmon has grown substantially in recent decades. But despite the infusion of resources, many studies suggest that salmon populations are continuing to decline, leading some to question the effectiveness of restoration efforts. Here we examine whether a particular form of salmon restoration—channel reconfiguration with gravel augmentation—generates physical and biological habitat that is comparable with other streams that support salmon. We compared a suite of habitat features known to influence the various life stages of Chinook salmon in a restoration project in California's Merced River with 19 other streams that also support Chinook that we surveyed in the same geographic region. Our survey showed that riffle habitats in the restored site of the Merced River have flow discharge and depth, substrate and food web characteristics that cannot be distinguished from other streams that support Chinook, suggesting that these factors are unlikely to be bottlenecks to salmon recovery in the Merced. However, compared with other streams in the region, the Merced has minimal riparian cover, fewer undercut banks, less woody debris and higher water temperatures, suggesting that these factors might limit salmon recovery. After identifying aspects in the Merced that differ from other streams, we used principal components analysis to correlate salmon densities to independent axes of environmental variation measured during our survey. These analyses suggested that salmon densities tend to be greatest in streams that have more undercut banks and woody debris and lower water temperatures. These are the same environmental factors that appear to be missing from the Merced River restoration effort. Collectively, our results narrow the set of candidate factors that may limit salmon recovery in channel reconfiguration restoration efforts. Copyright © 2012 John Wiley & Sons, Ltd.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97512/1/rra1604.pd

    Boxicity of graphs on surfaces

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    The boxicity of a graph G=(V,E)G=(V,E) is the least integer kk for which there exist kk interval graphs Gi=(V,Ei)G_i=(V,E_i), 1ik1 \le i \le k, such that E=E1...EkE=E_1 \cap ... \cap E_k. Scheinerman proved in 1984 that outerplanar graphs have boxicity at most two and Thomassen proved in 1986 that planar graphs have boxicity at most three. In this note we prove that the boxicity of toroidal graphs is at most 7, and that the boxicity of graphs embeddable in a surface Σ\Sigma of genus gg is at most 5g+35g+3. This result yields improved bounds on the dimension of the adjacency poset of graphs on surfaces.Comment: 9 pages, 2 figure

    Pregnancy and childbirth in English prisons : institutional ignominy and the pains of imprisonment

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    © 2020 The Authors. Sociology of Health & Illness published by John Wiley & Sons Ltd on behalf of Foundation for SHIL.With a prison population of approximately 9000 women in England, it is estimated that approximately 600 pregnancies and 100 births occur annually. Despite an extensive literature on the sociology of reproduction, pregnancy and childbirth among women prisoners is under‐researched. This article reports an ethnographic study in three English prisons undertaken in 2015‐2016, including interviews with 22 prisoners, six women released from prison and 10 staff members. Pregnant prisoners experience numerous additional difficulties in prison including the ambiguous status of a pregnant prisoner, physical aspects of pregnancy and the degradation of the handcuffed or chained prisoner during visits to the more public setting of hospital. This article draws on Erving Goffman's concepts of closed institutions, dramaturgy and mortification of self, Crewe et al.'s work on the gendered pains of imprisonment and Crawley's notion of ‘institutional thoughtlessness’, and proposes a new concept of institutional ignominy to understand the embodied situation of the pregnant prisoner.Peer reviewe

    Evolution of a unique predatory feeding apparatus: functional anatomy, development and a genetic locus for jaw laterality in Lake Tanganyika scale-eating cichlids

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    Background While bilaterality is a defining characteristic of triploblastic animals, several assemblages have managed to break this symmetry in order to exploit the adaptive peaks garnered through the lateralization of behaviour or morphology. One striking example of an evolved asymmetry in vertebrates comes from a group of scale-eating cichlid fishes from Lake Tanganyika. Members of the Perissodini tribe of cichlid fishes have evolved dental and craniofacial asymmetries in order to more effectively remove scales from the left or right flanks of prey. Here we examine the evolution and development of craniofacial morphology and laterality among Lake Tanganyika scale-eating cichlids. Results Using both geometric and traditional morphometric methods we found that the craniofacial evolution in the Perissodini involved discrete shifts in skeletal anatomy that reflect differences in habitat preference and predation strategies. Further, we show that the evolutionary history of the Perissodini is characterized by an accentuation of craniofacial laterality such that certain taxa show elaborate sided differences in craniofacial shape consistent with the sub-partitioning of function between sides of the head during attacks. Craniofacial laterality in the scale-eating specialist Perissodus microlepis was found to be evident early in development and exhibited a unimodal distribution, which is contrary to the adult condition where jaw laterality has been described as a discrete, bimodal antisymmetry. Finally, using linkage and association analyses we identified a conserved locus for jaw handedness that segregates among East African cichlids. Conclusions We suggest that, during the evolution of the Perissodini, selection has accentuated a latent, genetically determined handedness of the craniofacial skeleton, enabling the evolution of jaw asymmetries in order to increase predation success. Continued work on the developmental genetic basis of laterality in the Perissodini will facilitate a better understanding of the evolution of this unique group of fishes, as well as of left-right axis determination among vertebrates in general

    Approximate min-max relations on plane graphs

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    Let G be a plane graph, let τ(G) (resp. τ′(G)) be the minimum number of vertices (resp. edges) that meet all cycles of G, and let ν(G) (resp. ν′(G)) be the maximum number of vertex-disjoint (resp. edge-disjoint) cycles in G. In this note we show that τ(G)≤3 ν(G) and τ′(G)≤4 ν′(G)-1; our proofs are constructive, which yield polynomial-time algorithms for finding corresponding objects with the desired properties. © 2011 The Author(s).published_or_final_versionSpringer Open Choice, 28 May 201

    Epidemic of illicit drug use, mechanisms of action/addiction and stroke as a health hazard

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    Drug abuse robs individuals of their jobs, their families, and their free will as they succumb to addiction; but may cost even more: a life of disability or even life lost due to stroke. Many illicit drugs have been linked to major cardiovascular events and other comorbidities, including cocaine, amphetamines, ecstasy, heroin, phencyclidine, lysergic acid diethylamide, and marijuana. This review focuses on available epidemiological data, mechanisms of action, particularly those leading to cerebrovascular events, and it is based on papers published in English in PubMed during 1950 through February 2011. Each drug's unique interactions with the brain and vasculature predispose even young, healthy people to ischemic or hemorrhagic stroke. Cocaine and amphetamines have the strongest association with stroke. However, the level of evidence firmly linking other drugs to stroke pathogenesis is weak. Large epidemiological studies and systematic evaluation of each drug's action on the brain and cardiovascular system are needed to reveal the full impact of drug use on the population

    The Cyprinodon variegatus genome reveals gene expression changes underlying differences in skull morphology among closely related species

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    Genes in durophage intersection set at 15 dpf. This is a comma separated table of the genes in the 15 dpf durophage intersection set. Given are edgeR results for each pairwise comparison. Columns indicating whether a gene is included in the intersection set at a threshold of 1.5 or 2 fold are provided. (CSV 13 kb
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