531 research outputs found

    Effects of moose foraging on browse availability in New Hampshire deer yards

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    Food habits of moose (Alces alces) and white-tailed deer (Odocoileus virginianus) overlap in northern New Hampshire during autumn and winter. High moose and deer densities in deer yards, where deer may be confined for extended periods, could result in competition for limited deciduous forage. The purpose of this study was to investigate possible impacts by moose on browse availability in deer yards, and the potential effects on deer. Fifteen deer yards were studied in northern New Hampshire during spring and fall, 1990-91. Unbrowsed and browsed deciduous twigs, and deer and moose pellet groups were counted on 900 permanent plots to measure seasonal browse use and population density of deer and moose. Twig biomass availability and removal were estimated for each season in all areas. Combined data from all deer yards showed that unbrowsed biomass increased between spring 1990 and autumn 1990, and decreased between autumn 1990 and spring 1991. Moose browsed 7.2% of available food during autumn 1989 and winter 1990, 7.7% during autumn 1990, and 3.8% during winter 1991, accounting for 26.3%, 81.1%, and 17.6% of browsed biomass, respectively. One-year-old clearcuts adjacent to wintering areas were heavily browsed, particularly during the winter. Preferred moose foods during autumn were quaking aspen and mountain maple. Pin cherry and nannyberry were removed relative to availability. Moose have the potential to substantially reduce the availability of preferred deciduous browse (e.g. maples) of deer, and thus reduce the carrying capacity of deer yards. Specialized management in areas of high moose density may be warranted where clearcuts adjacent to deer yards provide the essential winter forage of deer

    Qualitative characterization of healthcare wastes

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    The biological hazard inherent in the clinical wastes should be considered during the management and treatment process as well as the disposal into the environment. In this chapter, the risks associated with the clinical wastes as well as the management of these wastes are discussed. The chapter focused on reviewing the types of healthcare wastes generated from hospitals and clinics as well as the regulations and management practices used for these wastes. Moreover, the health risk associated with the infectious agents which have the potential to be transmitted into the environment. It has appeared that the clinical wastes represent real hazards for the human health and the environment if they were not managed properly

    Integrating transposable elements in the 3D genome

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    Chromosome organisation is increasingly recognised as an essential component of genome regulation, cell fate and cell health. Within the realm of transposable elements (TEs) however, the spatial information of how genomes are folded is still only rarely integrated in experimental studies or accounted for in modelling. Whilst polymer physics is recognised as an important tool to understand the mechanisms of genome folding, in this commentary we discuss its potential applicability to aspects of TE biology. Based on recent works on the relationship between genome organisation and TE integration, we argue that existing polymer models may be extended to create a predictive framework for the study of TE integration patterns. We suggest that these models may offer orthogonal and generic insights into the integration profiles (or "topography") of TEs across organisms. In addition, we provide simple polymer physics arguments and preliminary molecular dynamics simulations of TEs inserting into heterogeneously flexible polymers. By considering this simple model, we show how polymer folding and local flexibility may generically affect TE integration patterns. The preliminary discussion reported in this commentary is aimed to lay the foundations for a large-scale analysis of TE integration dynamics and topography as a function of the three-dimensional host genome

    Functional diversity of marine ecosystems after the Late Permian mass extinction event

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    Article can be accessed from http://www.nature.com/ngeo/journal/v7/n3/full/ngeo2079.htmlThe Late Permian mass extinction event was the most severe such crisis of the past 500 million years and occurred during an episode of global warming. It is assumed to have had significant ecological impact, but its effects on marine ecosystem functioning are unknown and the patterns of marine recovery are debated. We analysed the fossil occurrences of all known Permian-Triassic benthic marine genera and assigned each to a functional group based on their inferred life habit. We show that despite the selective extinction of 62-74% of marine genera there was no significant loss of functional diversity at the global scale, and only one novel mode of life originated in the extinction aftermath. Early Triassic marine ecosystems were not as ecologically depauperate as widely assumed, which explains the absence of a Cambrian-style Triassic radiation in higher taxa. Functional diversity was, however, significantly reduced in particular regions and habitats, such as tropical reefs, and at these scales recovery varied spatially and temporally, probably driven by migration of surviving groups. Marine ecosystems did not return to their pre-extinction state, however, and radiation of previously subordinate groups such as motile, epifaunal grazers led to greater functional evenness by the Middle Triassic

    Environmental and diagenetic controls on the morphology and calcification of the Ediacaran metazoan Cloudina

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    Abstract Cloudina is a globally distributed Ediacaran metazoan, with a tubular, funnel-in-funnel form built of thin laminae (ca. 1–10 μm). To what degree local environmental controlled morphology, and whether early diagenesis controlled the degree of calcification of Cloudina, is debated. Here we test these hypotheses by considering assemblages from four, coeval localities from the Upper Omkyk Member, Nama Group, Namibia, from inner ramp to mid-ramp reef across the Zaris Subbasin. We show that sinuosity of the Cloudina tube is variable between sites, as is the relative thickness of the tube wall, suggesting these features were environmentally controlled. Walls are thickest in high-energy reef settings, and thinnest in the low-energy, inner ramp. While local diagenesis controls preservation, all diagenetic expressions are consistent with the presence of weakly calcified, organic-rich laminae, and lamina thicknesses are broadly constant. Finally, internal ‘cements’ within Cloudina are found in all sites, and pre-date skeletal breakage, transport, as well as syn-sedimentary botryoidal cement precipitation. Best preservation shows these to be formed by fine, pseudomorphed aragonitic acicular crystals. Sr concentrations and Mg/Ca show no statistically significant differences between internal Cloudina cements and botryoidal cements, but we infer all internal cements to have precipitated when Cloudina was still in-situ and added considerable mechanical strength, but may have formed post-mortem or in abandoned parts of the skeleton
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