Optical bistability for two-level atoms in a standing-wave cavity

Observations of optical bistability are reported for a system composed of multiple atomic beams passing through a high-finesse optical cavity. Both the transmitted power and the intracavity fluorescent intensity have been recorded as functions of incident laser power for zero cavity and atomic detunings. A quantitative study has been made of the evolution of the steady-state switching intensities from well below the critical onset of bistability to well above this point. The results show reasonable agreement with a Gaussian-beam theory of optical bistability, but systematic departures are noted

The WTO Special Safeguard Mechanism: A Case Study of Wheat

A special safeguard mechanism is an attractive policy tool for low income importing countries because it is automatic and does not require an injury test. Exporters might accept a safeguard for low income countries if it results in larger tariff cuts than in its absence. Using wheat as a case study the effects of a special safeguard mechanism on market stability and welfare are evaluated. The results show that a safeguard mechanism is not very trade distorting and costs less than 20 percent of the world welfare gain that would be realized if developing countries were not granted a safeguard.International Relations/Trade,

Triggers, Remedies and Tariff Cuts: Assessing the Impact of a Special Safeguard Mechanism for Developing Countries

On July 30, 2008, the WTO negotiations broke down because Members could not bridge their differences on the operation of a Special Safeguard Mechanism (SSM) for low-income countries. This study evaluates two scenarios concerning the recent July (2008) SSM proposal – one in which low-income countries are allowed to breach their pre-Doha bound tariffs and one in which they are not -- using a global, stochastic, partial equilibrium model of world wheat markets. We find that the July (2008) SSM proposal is not very trade distorting despite leading to sizeable SSM duties. Moreover, the question of whether developing countries should be allowed to exceed their pre-Doha bound tariffs depends heavily on the product under consideration, the extent of tariff cuts to bound rates, and the gap between a Members bound and applied tariffs, particularly when the volume-based SSM remedies are usedWTO, SSM, special safeguard mechanism, Doha, Agricultural and Food Policy, International Relations/Trade,

Triggers, Remedies, and Tariff Cuts: Assessing the Impact of a Special Safeguard Mechanism for Developing Countries

The WTO negotiations broke down on July 30th, 2008 because members could not bridge their differences over the operation of a Special Safeguard Mechanism (SSM). This article evaluates the latest SSM proposal using the world wheat market as our case study. Whether low-income WTO members should be allowed to breach their pre-Doha bound tariffs is a key element of our analysis. The SSM leads to sizeable additional duties but is not very trade distorting, even when pre-Doha bound rates are breached. Moreover, the extent to which low-income countries should be allowed to exceed pre-Doha bound rates depends heavily on the product under consideration, the ambition of the tariff cutting exercise, and the gap between members’ bound and applied tariffs.agriculture, Doha Development Agenda, July Package, Special Safeguard Mechanism, World Trade Organization, International Relations/Trade,

IMPORT SAFEGUARDS: PROTECTIONIST MEASURES OR A LIBERALIZATION STRATEGY?

The Doha Trade Round maintains that a considerable effort will be given to take into account better the particular needs of developing nations. Many low-income countries argue that the flexibility to invoke a special safeguard mechanism when faced with volatile commodity markets is a necessary condition for further market access reform. The implications of a safeguard for developing agriculture as a trade-off for lowering their tariff rates, is an important empirical question. Two stochastic simulation experiments are developed using wheat as a case study to estimate the marginal effects of a safeguard in terms of domestic market stability and on developed exporting nations. The results reveal that a safeguard for developing agriculture is minimally trade distorting and in general, costs less than one percent of total world welfare that would be realized if low-income countries were not granted a safeguard. Furthermore, safeguards are an attractive policy tool because they are transparent, easy to use and are an automatic mechanism.International Relations/Trade,

Measuring unsteady pressure on rotating compressor blades

Miniature semiconductor strain gage pressure transducers mounted in several arrangements were studied. Both surface mountings and recessed flush mountings were tested. Test parameters included mounting arrangement, blade material, temperature, local strain in the acceleration normal to the transducer diaphragm, centripetal acceleration, and pressure. Test results show no failures of transducers or mountings and indicate an uncertainty of unsteady pressure measurement of approximately + or - 6 percent + 0.1 kPa for a typical application. Two configurations were used on a rotating fan flutter program. Examples of transducer data and correction factors are presented

THE SPECIAL SAFEGUARD MECHANISM IN THE DOHA DEVELOPMENT AGENDA: A CASE STUDY OF SOYBEANS

The Special Safeguard Mechanism (SSM) proposed for developing countries has become a thorny issue in the Doha Development Agenda’s (DDA) agricultural negotiations. Proponents of the mechanism argue that it is a necessary compromise to counter sharp price declines or rapid import surges in staple commodity markets of developing nations. Opponents of the SSM, which include many developed exporters, contend that the policy flexibility contained in current SSM proposals would severely limit market access if the mechanism is triggered. The impact of the SSM depends on a number of parameters: the number of times the SSM is triggered, whether the price or volume SSM is triggered, the size of current tariffs, the magnitude with which tariffs are reduced in the DDA, and the number of times a developing country will actually make use of the SSM. This study introduces a static, synthetic, global, partial equilibrium model of the world soybean complex to assess the preliminary aspects of the DDA’s proposed tariff cuts. Future work on this project will extend the model to a stochastic framework from which to simulate the effects of an SSM combined with the DDA tariff cutting formulas for developing nations.Agribusiness,

The Chelsea Critical Care Physical Assessment Tool (CPAx): validation of an innovative new tool to measure physical morbidity in the general adult critical care population; an observational proof-of-concept pilot study.

Objective To develop a scoring system to measure physical morbidity in critical care – the Chelsea Critical Care Physical Assessment Tool (CPAx). Method The development process was iterative involving content validity indices (CVI), a focus group and an observational study of 33 patients to test construct validity against the Medical Research Council score for muscle strength, peak cough flow, Australian Therapy Outcome Measures score, Glasgow Coma Scale score, Bloomsbury sedation score, Sequential Organ Failure Assessment score, Short Form 36 (SF-36) score, days of mechanical ventilation and inter-rater reliability. Participants Trauma and general critical care patients from two London teaching hospitals. Results Users of the CPAx felt that it possessed content validity, giving a final CVI of 1.00 (P < 0.05). Construct validation data showed moderate to strong significant correlations between the CPAx score and all secondary measures, apart from the mental component of the SF-36 which demonstrated weak correlation with the CPAx score (r = 0.024, P = 0.720). Reliability testing showed internal consistency of α = 0.798 and inter-rater reliability of κ = 0.988 (95% confidence interval 0.791 to 1.000) between five raters. Conclusion This pilot work supports proof of concept of the CPAx as a measure of physical morbidity in the critical care population, and is a cogent argument for further investigation of the scoring system

Status of Marine Birds of the Southeastern Beaufort Sea

This summary and update of information on the marine birds of the southeastern Beaufort Sea is intended to support discussions on how to improve management of marine resources in the Canadian Beaufort Sea region. Perhaps the most outstanding use of the Beaufort Sea by marine birds is the staging during spring migration by hundreds of thousands of eiders and long-tailed ducks in the early open water off Cape Bathurst and Banks Island. During midsummer, tens of thousands of long-tailed ducks, scoters, scaup, and mergansers moult in the sheltered bays and behind barrier beaches and spits. Although several species of geese, ducks, loons, gulls, and terns nest on islands and in wetlands along the Beaufort Sea coast, this region has relatively few nesting seabirds compared to eastern Arctic Canada and the Bering Sea. Two possible reasons for this are a shortage of cliffs suitable for nesting and a lack of pelagic fish. The five most common sea duck species that occur in the region, long-tailed duck, king eider, common eider, surf scoter, and white-winged scoter, have all declined in numbers since the mid-1970s. Western Arctic brant populations have also declined, although their status within the Beaufort Sea region is unclear. Brant and king eider are the only marine bird species harvested there in substantial numbers. Other threats to Beaufort Sea marine bird populations include oil spills, global warming, coastal development, and contaminants. Certain threats can be managed at a local level since they are a result of local economic development, but others, such as global warming or loss of critical wintering areas, stem from environmental problems outside the region. Solving these issues will require mutual understanding and commitment on the part of numerous countries.Cette récapitulation et mise à jour de l'information sur les oiseaux marins du sud-est de la mer de Beaufort ont été faites dans le but de fournir des arguments sur la façon d'améliorer la gestion des ressources marines dans la zone canadienne de la mer de Beaufort. L'utilisation la plus notable que font les oiseaux marins de la mer de Beaufort est peut-être en tant que halte durant la migration printanière de centaines de milliers d'eiders et de canards à longue queue dans les premières eaux libres au large du cap Bathurst et de l'île Banks. Au milieu de l'été, des dizaines de milliers de canards à longue queue, de macreuses, de fuligules milouinans et de harles muent dans les baies abritées et en arrière des flèches et cordons littoraux. Même si plusieurs espèces d'oies, de canards, de huarts, de mouettes et de sternes nichent sur les îles et dans les zones humides longeant le rivage de la mer de Beaufort, cette région voit relativement peu d'oiseaux marins qui viennent y nicher en comparaison de l'est du Canada arctique et de la mer de Béring. Il y a deux raisons possibles à cet état de choses: trop peu de falaises propices à l'établissement de nids et un manque de poissons pélagiques. Les cinq espèces de canards de mer les plus courantes dans la région, à savoir, le canard à longue queue, l'eider à tête grise, l'eider à duvet, la macreuse à front blanc et la macreuse brune, ont toutes vu leurs nombres décliner depuis le milieu des années 1970. La population de bernaches cravants de l'ouest de l'Arctique est également en déclin, bien que le statut de cet oiseau au sein de la région de la mer de Beaufort ne soit pas évident. La bernache cravant et l'eider à tête grise sont les seules espèces d'oiseaux marins prélevées en nombre important à cet endroit. Parmi les autres facteurs qui menacent les populations d'oiseaux marins de la mer de Beaufort, on compte les déversements d'hydrocarbures, le réchauffement climatique, l'aménagement du littoral et les contaminants. Certaines menaces peuvent être gérées au niveau local vu qu'elles résultent du développement économique local, mais d'autres comme le réchauffement climatique ou la perte d'aires d'hivernage critiques sont issues d'enjeux environnementaux extérieurs à la région. La résolution de ces problèmes passe obligatoirement par une compréhension et un engagement mutuels de la part de nombreux pays

Significance of solutions of the inverse Biot-Savart problem in thick superconductors

The evaluation of current distributions in thick superconductors from field profiles near the sample surface is investigated theoretically. A simple model of a cylindrical sample, in which only circular currents are flowing, reduces the inversion to a linear least squares problem, which is analyzed by singular value decomposition. Without additional assumptions about the current distribution (e.g. constant current over the sample thickness), the condition of the problem is very bad, leading to unrealistic results. However, any additional assumption strongly influences the solution and thus renders the solutions again questionable. These difficulties are unfortunately inherent to the inverse Biot-Savart problem in thick superconductors and cannot be avoided by any models or algorithms