328 research outputs found
An Attack by a Polar Bear on a Juvenile Beluga
Cunningham Inlet, Somerset Island, in the Canadian Arctic is frequented each summer by large numbers of beluga (Delphinapterus leucas). They migrate to the head of the inlet, and then invade the mouths of the two streams which drain into it. … On 26 July 1974, a sexually-immature female beluga was discovered stranded on a gravel bar at the head of the inlet. Because it could not be manhandled back to water, and would have died from suffocating and dehydration, the whale was shot. The brown colour, shape of head and length (271 cm) of the animal suggested that it was between three and four years old, while the five to six growth layers present in the teeth indicated an age of 2½-3 years. The stomach was found to contain a few amphipods and some seaweed. The carcass carried deep but well-healed scars on the left dorso-lateral aspect caudal to the dorsal ridge. Their depth, and the fact that they were parallel in three cases, strongly suggested that the animal had been attacked by a large-clawed animal, probably a polar bear (Ursus maritimus). … To our knowledge this paper constitutes only the third documented account of an attack on a beluga by a polar bear in the Canadian Arctic …. [All previously reported attacks, including an attack of captive belugas near Churchill, are also discussed in this article.
A global map to aid the identification and screening of critical habitat for marine industries
Marine industries face a number of risks that necessitate careful analysis prior to making decisions on the siting of operations and facilities. An important emerging regulatory framework on environmental sustainability for business operations is the International Finance Corporationâs Performance Standard 6 (IFC PS6). Within PS6, identification of biodiversity significance is articulated through the concept of âCritical Habitatâ, a definition developed by the IFC and detailed through criteria aligned with those that support internationally accepted biodiversity designations. No publicly available tools have been developed in either the marine or terrestrial realm to assess the likelihood of sites or operations being located within PS6-defined Critical Habitat. This paper presents a starting point towards filling this gap in the form of a preliminary global map that classifies more than 13 million km2 of marine and coastal areas of importance for biodiversity (protected areas, Key Biodiversity Areas [KBA], sea turtle nesting sites, cold- and warm-water corals, seamounts, seagrass beds, mangroves, saltmarshes, hydrothermal vents and cold seeps) based on their overlap with Critical Habitat criteria, as defined by IFC. In total, 5798Ă103 km2 (1.6%) of the analysis area (global ocean plus coastal land strip) were classed as Likely Critical Habitat, and 7526Ă103 km2 (2.1%) as Potential Critical Habitat; the remainder (96.3%) were Unclassified. The latter was primarily due to the paucity of biodiversity data in marine areas beyond national jurisdiction and/or in deep waters, and the comparatively fewer protected areas and KBAs in these regions. Globally, protected areas constituted 65.9% of the combined Likely and Potential Critical Habitat extent, and KBAs 29.3%, not accounting for the overlap between these two features. Relative Critical Habitat extent in Exclusive Economic Zones varied dramatically between countries. This work is likely to be of particular use for industries operating in the marine and coastal realms as an early screening aid prior to in situ Critical Habitat assessment; to financial institutions making investment decisions; and to those wishing to implement good practice policies relevant to biodiversity management. Supplementary material (available online) includes other global datasets considered, documentation and justification of biodiversity feature classification, detail of IFC PS6 criteria/scenarios, and coverage calculations
A Study of Single-Particle Parity-Nonconserving Nuclear Matrix Elements
This research was sponsored by the National Science Foundation Grant NSF PHY-931478
Constraints on the Variations of the Fundamental Couplings
We reconsider several current bounds on the variation of the fine-structure
constant in models where all gauge and Yukawa couplings vary in an
interdependent manner, as would be expected in unified theories. In particular,
we re-examine the bounds established by the Oklo reactor from the resonant
neutron capture cross-section of 149Sm. By imposing variations in \Lambda_{QCD}
and the quark masses, as dictated by unified theories, the corresponding bound
on the variation of the fine-structure constant can be improved by about 2
orders of magnitude in such theories. In addition, we consider possible bounds
on variations due to their effect on long lived \alpha- and \beta-decay
isotopes, particularly 147Sm and 187Re. We obtain a strong constraint on \Delta
\alpha / \alpha, comparable to that of Oklo but extending to a higher redshift
corresponding to the age of the solar system, from the radioactive life-time of
187Re derived from meteoritic studies. We also analyze the astrophysical
consequences of perturbing the decay Q values on bound state \beta-decays
operating in the s-process.Comment: 25 pages, latex, 5 eps figure
Invisible Axions and Large-Radius Compactifications
We study some of the novel effects that arise when the QCD axion is placed in
the ``bulk'' of large extra spacetime dimensions. First, we find that the mass
of the axion can become independent of the energy scale associated with the
breaking of the Peccei-Quinn symmetry. This implies that the mass of the axion
can be adjusted independently of its couplings to ordinary matter, thereby
providing a new method of rendering the axion invisible. Second, we discuss the
new phenomenon of laboratory axion oscillations (analogous to neutrino
oscillations), and show that these oscillations cause laboratory axions to
``decohere'' extremely rapidly as a result of Kaluza-Klein mixing. This
decoherence may also be a contributing factor to axion invisibility. Third, we
discuss the role of Kaluza-Klein axions in axion-mediated processes and decays,
and propose several experimental tests of the higher-dimensional nature of the
axion. Finally, we show that under certain circumstances, the presence of an
infinite tower of Kaluza-Klein axion modes can significantly accelerate the
dissipation of the energy associated with cosmological relic axion
oscillations, thereby enabling the Peccei-Quinn symmetry-breaking scale to
exceed the usual four-dimensional relic oscillation bounds. Together, these
ideas therefore provide new ways of obtaining an ``invisible'' axion within the
context of higher-dimensional theories with large-radius compactifications.Comment: 43 pages, LaTeX, 6 figure
Coherent matter wave inertial sensors for precision measurements in space
We analyze the advantages of using ultra-cold coherent sources of atoms for
matter-wave interferometry in space. We present a proof-of-principle experiment
that is based on an analysis of the results previously published in [Richard et
al., Phys. Rev. Lett., 91, 010405 (2003)] from which we extract the ratio h/m
for 87Rb. This measurement shows that a limitation in accuracy arises due to
atomic interactions within the Bose-Einstein condensate
Singularities In Scalar-Tensor Cosmologies
In this article, we examine the possibility that there exist special
scalar-tensor theories of gravity with completely nonsingular FRW solutions.
Our investigation in fact shows that while most probes living in such a
Universe never see the singularity, gravity waves always do. This is because
they couple to both the metric and the scalar field, in a way which effectively
forces them to move along null geodesics of the Einstein conformal frame. Since
the metric of the Einstein conformal frame is always singular for
configurations where matter satisfies the energy conditions, the gravity wave
world lines are past inextendable beyond the Einstein frame singularity, and
hence the geometry is still incomplete, and thus singular. We conclude that the
singularity cannot be entirely removed, but only be made invisible to most, but
not all, probes in the theory.Comment: 23 pages, latex, no figure
From Expert Administration to Accountability Network: A New Paradigm for Comparative Administrative Law
Notwithstanding the radically changed landscape of contemporary administrative governance, the categories that guide comparative administrative law and that determine what will be compared remain similar to those used at the founding of the discipline in the late 1800s. These categories are rooted in confidence in an expert bureaucracy to accomplish public purposes and are mainly twofold - administrative organization and judicial review. This outdated model has limited the ability of comparative law to engage with contemporary debates on the administrative state, which instead display considerable skepticism of public administration and are premised on achieving the public good through a plural accountability network of public and private actors. This Article seeks to correct the anachronism by reframing comparative administrative law as an accountability network of rules and procedures designed to embed public administration and civil servants in their liberal democratic societies: accountability to elected officials, organized interests, the courts, and the general public. Based on this paradigm, the Article compares American and European administrative law in a global context. Among the many differences explored are parliamentary versus presidential political control, pluralist versus neo-corporatist forms of self-regulation and public-private collaboration, judicial review focused on fundamental rights versus policy rationality, and reliance on ombudsmen in lieu of courts. The Article concludes with a number of suggestions for how comparative law can speak to current debates on reforming administrative governance
The âmosaic habitatâ concept in human evolution: past and present
The habitats preferred by hominins and other species are an important theme in palaeoanthropology, and the âmosaic habitatâ (also referred to as habitat heterogeneity) has been a central concept in this regard for the last four decades. Here we explore the development of this concept â loosely defined as a range of different habitat types, such as woodlands, riverine forest and savannah within a limited spatial areaâ in studies of human evolution in the last sixty years or so. We outline the key developments that took place before and around the time when the term âmosaicâ came to wider palaeoanthropological attention. To achieve this we used an analysis of the published literature, a study of illustrations of hominin evolution from 1925 onwards and an email survey of senior researchers in palaeoanthropology and related fields. We found that the term mosaic starts to be applied in palaeoanthropological thinking during the 1970âs due to the work of a number of researchers, including Karl Butzer and Glynn Isaac , with the earliest usage we have found of âmosaicâ in specific reference to hominin habitats being by Adriaan Kortlandt (1972). While we observe a steady increase in the numbers of publications reporting mosaic palaeohabitats, in keeping with the growing interest and specialisation in various methods of palaeoenvironmental reconstruction, we also note that there is a lack of critical studies that define this habitat, or examine the temporal and spatial scales associated with it. The general consensus within the field is that the concept now requires more detailed definition and study to evaluate its role in human evolution
- âŠ