98 research outputs found
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Nonlinear optics: the next decade
No full textThis paper concludes the Focus Serial assembled of invited
papers in key areas of nonlinear optics (Editors: J.M. Dudley and R.W.
Boyd), and it discusses new directions for future research in this field
Experimental evidence of a double layer in a large volume helicon reactor
No full textThe self-consistently generated current-free electric double layer (DL) is shown to scale up with the source tube diameter and appears not to be affected by rf driving frequency and changes in reactor geometry. This Letter presents the first simultaneous measurements of local plasma potential and beam energy as a function of axial position. The DL is shown to be no more than 5 mm thick (20 D lengths) and positioned just downstream of the maximum in the magnetic field gradient. Furthermore, its position relative to the magnetic field is observed to be invariant as the magnetic field is translated axially. Measurements of the potential drop across the DL are presented for pressures down to 0.09 mTorr and the DL strength (ϕDL/Te) is determined to be between 5 and 7
Impact of genetic testing on life insurance
No full textThe Human Genome project generates immense interest in the scientific
community though there are also important issues for the business
community, particularly insurance companies. The dramatic advances in
our understanding of the human genetic code, or human genome, affect our
understanding of the determinants of human longevity and this is critical to the
profitability of life insurance contracts
Transnational corruption: regulation across borders
No full textThe global upsurge of interest in corruption has led to the proliferation of anti-corruption instruments in international law. Such legal responses to corruption may be usefully divided into three interrelated planes of action: the promulgation of formal international legal instruments by organisations such as the UN and OECD; the work of national bureaucratic agencies cooperating across borders to enforce national anti-corruption laws; and the work of wholly non-governmental organisations such as Transparency International. The difficult task of regulating transnational
actors, particularly corporations, requires an understanding of how these planes interact, and which elements would best be strengthened to further the fight against corruption. Furthermore, such regulation must carefully balance questions of efficacy against those of legitimacy. The purpose of this paper is to assess modern regulatory literature, particularly regarding corporate
behaviour, and draw from it lessons for the development of the international anti-corruption legal regime
No intra-locus sexual conflict over reproductive fitness or ageing in field crickets
No full textDifferences in the ways in which males and females maximize evolutionary fitness can lead to intra-locus sexual conflict in which genes delivering fitness benefits to one sex are costly when expressed in the other. Trade-offs between current reproductive effort and future reproduction and survival are fundamental to the evolutionary biology of ageing. This leads to the prediction that sex differences in the optimization of age-dependent reproductive effort may generate intra-locus sexual conflict over ageing rates. Here we test for intra-locus sexual conflict over age-dependent reproductive effort and longevity in the black field cricket, Teleogryllus commodus. Using a half-sib breeding design, we show that the most important components of male and female reproductive effort (male calling effort and the number of eggs laid by females) were positively genetically correlated, especially in early adulthood. However, the genetic relationships between longevity and reproductive effort were different for males and females, leading to low genetic covariation between male and female longevity. The apparent absence of intra-locus sexual conflict over ageing suggests that male and female longevity can evolve largely independently of one another
The nomenclature of the African wild ass
No full textThe 19th-century reports on the occurrence and identity of wild asses in North-East Africa are reviewed,
as well as the names applied in various publications by Fitzinger and von Heuglin, respectively. The
first published name for the African wild ass, Asinus africanus Fitzinger, 1858, is a nomen nudum. The
name Equus taeniopus von Heuglin, 1861 is rejected as indeterminable, as it is based on an animal that
cannot be identified and may have been a hybrid between a domestic donkey and a Somali wild ass; the
type has not been preserved. The first available name thus becomes Asinus africanus von Heuglin &
Fitzinger, 1866. A lectotype is designated: a skull of an adult female collected by von Heuglin near Atbara
River, Sudan, and present in the Museum für Naturkunde in Stuttgart, MNS 32026. A review of
taxonomic and nomenclatural actions by later authors is given. The two subspecies recognized are the
Nubian wild ass Equus a. africanus (von Heuglin & Fitzinger, 1866), and the Somali wild ass E. a. somaliensis
(Noack, 1884)
Coherent and incoherent contributions to multisoliton complexes
No full textWe analyze multisoliton complexes and their dynamics in Kerr-like nonlinear media. The field in
each of M incoherently interacting components is calculated using an integrable set of coupled nonlinear
Schrödinger equations. We obtain a general N-soliton solution describing propagation of multisoliton
complexes and their collisions. The evolution of such higher-order soliton beams is determined
by coherent and incoherent contributions from fundamental solitons. These internal interactions are
revealed and illustrated by numerical examples. This theory can be applied to describe the properties
of incoherent solitons in a photorefractive medium since these are, essentially, multisoliton complexes
Monte Carlo simulation of non-conservative positron transport in pure argon
No full textThe main aim of this paper is to apply modern phenomenology and accurate Monte Carlo simulation techniques to obtain the same level of understanding of positron transport as has been achieved for electrons. To this end, a reasonably complete set of cross sections for low energy positron scattering in argon has been used to calculate transport coefficients of low energy positrons in pure argon gas subject to an electrostatic field. We have analyzed the main features of these coefficients and have compared the calculated values with those for electrons in the same gas. The particular focus is on the influence of the non-conservative nature of positronium formation. This effect is substantial, generally speaking much larger than any comparable effects in electron transport due to attachment and/or ionization. As a result several new phenomena have been observed, such as negative differential conductivity (NDC) in the bulk drift velocity, but with no indication of any NDC for the flux drift velocity. In addition, there is a drastic effect on the bulk longitudinal diffusion coefficient for positrons, which is reduced to almost zero, in contrast to the other components of the diffusion tensor, which have normal values. It is found that the best way of explaining these kinetic phenomena is by sampling real space distributions which reveal drastic modification of the usual Gaussian profile due to pronounced spatial differentiation of the positrons by energy
Linking local knowledge with global action: examining the Global Fund to Fight AIDS, Tuberculosis and Malaria through a knowledge system lens
No full textNew global public health institutions are increasingly emphasizing transparency in decision-making, developing-country ownership of projects and programmes, and merit- and performance-based funding. Such principles imply an institutional response to the challenge of bridging the "know-do gap", by basing decisions explicitly on results, evidence and best practice. Using a knowledge systems framework, we examine how the Global Fund to fight AIDS, Tuberculosis and Malaria has affected the ways in which knowledge is used in efforts to combat these diseases. We outline the formal knowledge system embedded in current rules and practices associated with the Global Fund's application process, and give three examples that illustrate the complexity of the knowledge system in action: human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) policy in China; successful applications from Haiti; and responses to changing research on malaria. These examples show that the Global Fund has created strong incentives for knowledge to flow to local implementers, but with little encouragement and few structures for the potentially valuable lessons from implementation to flow back to global best practice or research-based knowledge. The Global Fund could play an influential role in fostering much-needed learning from implementation. We suggest that three initial steps are required to start this process: acknowledging shared responsibility for learning across the knowledge system; analysing the Global Fund's existing data (and refining data collection over time); and supporting recipients and technical partners to invest resources in linking implementarion with best practice and research
Households’ willingness to pay for undergrounding electricity and telecommunications wires
No full textUnderground telecommunications and low-voltage electricity networks have
several advantages over overhead networks including reliability of supply, safety and
improved visual amenity. The economic viability of replacing existing overhead networks
with new underground networks depends on the value of these benefits to households, but
no complete value estimates are available in the literature. This paper represents a
contribution towards addressing this research gap. A stated choice survey is used to
estimate willingness-to-pay for undergrounding in established residential areas in
Canberra. Average willingness-to-pay is at least $6,838 per household and there is
significant variation in preferences over the population. The results suggest that benefits
would be highest in areas with higher household income and older residents where visual amenity, safety, tree trimming or restrictions on the use of yard space are of concern