4,897 research outputs found
Treeless vegetation of the Australian Alps
Based on 1222 floristic quadrat samples, 56 plant communities were identified in treeless vegetation in the Australian Alps of south-eastern Australia. (c. 35º 30´–38ºS, 146°–149°E). The study encompassed vegetation from above the upper limit of trees on mountain tops (i.e. the truly alpine environment) and below the inverted treeline in subalpine valleys. Generally, grasslands develop on deep humus soils, heathlands occur on shallower or rocky soils, and wetland communities are found in places of permanent or intermittent wetness. Duration of snow cover, lithology, altitude and exposure are also important determinants of the spatial arrangement of communities. Broadly, communities within a geographic region are more closely related to each other than to communities of similar structure or dominants from other geographic areas. Many communities are either very localised or are widespread with a small area of occupancy. Fourteen communities are probably eligible for listing as threatened, either alone or as aggregates with associated communities. A total of 710 native taxa from 82 families has been recorded. There is a high level of endemism – 30% of taxa are ± restricted to treeless vegetation in the Australia Alps and a further 14% are ± restricted to treeless vegetation but occur in mountain areas outside the Australian mainland (e.g. Tasmania and New Zealand). Thirteen taxa are listed in the Environment Protection and Biodiversity Conservation Act 1999 as threatened and a further 18 taxa are identified that may be eligible for listing as threatened nationally. 131 non-native taxa have been recorded in natural vegetation. Treeless vegetation has been intensively utilised since European settlement, initially as summer pastures for cattle and sheep but more recently as water catchments for electricity production and as tourist attractions both in winter and summer. Many communities are slowly recovering from past pressures and from the fires of 2003, which burnt most of the area for the first time since 1939. The treeless vegetation of the Australian Alps faces an uncertain future because of increased pressure from tourism and the unknown impacts of global warming
Vulture Poisoning Incidents and the Status of Vultures in Zambia and Malawi
Asia and Africa have experienced recent catastrophic declines in populations of most species of vultures (Thiollay 2006, Ogada et al. 2011, Virani et al. 2011). While the declines in Asia have been linked to poisoning by the veterinary drug diclofenac (Oaks et al. 2004), the reasons for the declines across Africa remain poorly understood (Ogada et al. 2011), and are likely to have multiple causes, such as poisoning and a decline in food supply
Lifetimes of Shockley electrons and holes at the Cu(111) surface
A theoretical many-body analysis is presented of the electron-electron
inelastic lifetimes of Shockley electrons and holes at the (111) surface of Cu.
For a description of the decay of Shockley states both below and above the
Fermi level, single-particle wave functions have been obtained by solving the
Schr\"odinger equation with the use of an approximate one-dimensional
pseudopotential fitted to reproduce the correct bulk energy bands and
surface-state dispersion. A comparison with previous calculations and
experiment indicates that inelastic lifetimes are very sensitive to the actual
shape of the surface-state single-particle orbitals beyond the
() point, which controls the coupling between the Shockley
electrons and holes.Comment: 4 pages, 3 figures, to appear in Phys. Rev.
Re United Food Processors Union, Local 483 and Canada Starch Co (Buker)
Employee grievance, pursuant to the Collective Agreement between the parties effective May 28, 1967, alleging improper assignment of work and requesting call-back pay of 4 hours at the regular rate of pay
Modeling the U.S. firearms market: the effects of civilian stocks, crime, legislation, and armed conflicte
This study represents an attempt to understand the U.S. firearms market – the largest in the world – in economic terms. A model of the underlying interplay of legal firearms supply and demand is a prerequisite for reliably evaluating the effectiveness of pertinent existing state and federal firearms policies, and to amend them as necessary. The stakes are high: compared to other nation-states, per capita firearms-related harm in the United States (including suicides and homicides) is exceptionally high and, within constitutional strictures, state and federal firearms policymakers increasingly view it as a major and pressing society-wide problem
Training and Assessment of Laparoscopic Skills
Laparoscopic surgery is gaining popularity among the surgical community. While its prevalence expands, the need for reliable training and assessment tools is becoming increasingly important. Laparoscopic skills are not an innate behavior, nor can they be easily mimicked, and can only be acquired through hands-on training. A consensus exists among physicians that establishment and evaluation of technical skill in surgical training programs are inadequate and in need of improvement. A validated, reliable bench model that could train and assess could be standardized and provide numerous benefits including determination of which medical students should consider a career in surgery, valuable feedback to residents, a tracking mechanism of resident performance, a possible certification and recertification tool, and to allow for interinstitutional comparison. To this end, several potentially successful bench models testing dexterity, hand-eye coordination, and depth perception have been developed. A few models have been proven to be both valid and reliable indicators of technical skill. Although the future remains uncertain, enough groundwork has been laid to begin incorporating technical skill training and assessment into surgical training programs
Researching the Aftermath of Slavery in Mainland East Africa: Methodological, Ethical, and Practical Challenges
This article examines ethical, practical, and methodological challenges in researching the aftermath of slavery in continental East Africa away from the coastal plantation belt. Interest in post-slavery there is recent and inspired by the apparent contrast with West Africa, where the issue is much more salient. The article explains this silence by highlighting politically-motivated avoidance of the issue in colonial sources and the preference of post-colonial historians for ‘useful’ pasts. Further, it questions the balance of successful integration and continuing marginalization reflected in the apparent obsolescence of slavery. It argues that tracing the trajectories of ex-slaves requires attention to all forms of social inequality and dependency, to the potential status implications for informants of speaking about slavery, and to the variety of terms and fields of meaning relevant to freedom, unfreedom and dependency. Recent research in this vein shows that slave antecedents remain a matter of aibu, shame, and that ex-slaves’ disappearance as a social category took lifelong efforts on their part. While the social valence of slave antecedents is relatively limited in mainland East Africa, slavery remains a problematic and painful heritage that demands great circumspection by researchers
Editorial: Teaching palaeosciences to future generations
Sec. Paleoecology
This article is part of the Research Topic:
Teaching Palaeosciences to Future Generation
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