2,446 research outputs found

    Accessing Rydberg-dressed interactions using many-body Ramsey dynamics

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    We demonstrate that Ramsey spectroscopy can be used to observe Rydberg-dressed interactions. In contrast to many prior proposals, our scheme operates comfortably within experimentally measured lifetimes, and accesses a regime where quantum superpositions are crucial. The key idea is to build a spin-1/2 from one level that is Rydberg-dressed and another that is not. These levels may be hyperfine or long-lived electronic states. An Ising spin model governs the Ramsey dynamics, for which we derive an exact solution. Due to the structure of Rydberg interactions, the dynamics differs significantly from that in other spin systems. As one example, spin echo can increase the rate at which coherence decays. The results also apply to bare (undressed) Rydberg states as a special case, for which we quantitatively reproduce recent ultrafast experiments without fitting

    The design and implementation of the Technical Facilities Controller (TFC) for the Goldstone deep space communications complex

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    The Technical Facilities Controller is a microprocessor-based energy management system that is to be implemented in the Deep Space Network facilities. This system is used in conjunction with facilities equipment at each of the complexes in the operation and maintenance of air-conditioning equipment, power generation equipment, power distribution equipment, and other primary facilities equipment. The implementation of the Technical Facilities Controller was completed at the Goldstone Deep Space Communications Complex and is now operational. The installation completed at the Goldstone Complex is described and the utilization of the Technical Facilities Controller is evaluated. The findings will be used in the decision to implement a similar system at the overseas complexes at Canberra, Australia, and Madrid, Spain

    Analysis of patient load data for teams competing in the 2003 Cricket World Cup in South Africa

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    Objectives. To evaluate the injury presentation data for all teams taking part in 10 warm-up matches and 46 matches during the 2003 Cricket World Cup played in South Africa, in order to provide organisers with the basis of a sound medical-care plan for future tournaments of a similar nature. Methods. The data collected included the role of the injured person, the nature of the injury, whether the treatment was for an injury or an illness, whether the injury was acute, chronic or acute-on-chronic, and the prognosis (rest, play, unfit to play, sent home, follow-up treatment required). The medical personnel in charge of the medical support documented patient information which included the total number of patient presentations and the category of illness/injury. Results. Ninety patient presentations (1.6 patient presentations per match) were recorded. The most common patient presentations were by the batsmen (50%), followed by the bowlers (29%) and all-rounders (17%). Of the patient presentations, 53% were classified as injuries, while the remaining 47% were classified as illnesses. The patient presentations occurred in the early stages of the competition. The most common presentations were of an acute nature (63%). The main injury pathology categories were trigger point injuries (10%), and bruises / abrasions (10%), while infection (29%) was the main illness pathology. Conclusions. The 2003 Cricket World Cup proved to be an ideal opportunity to collect data on international cricketers participating in an intensive 6-week international competition; the epidemiological data collected should assist national cricket bodies and organisers of future Cricket World Cup competitions to predict participant-related injury rates. South African Journal of Sports Medicine Vol. 18 (4) 2006: pp. 129-13

    Potential Effects of the Adoption and Implementation of International Financial Accounting Standards(IFRS)in Nigeria

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    The objective of this study is to examine the potential effects of the adoption and implementation of IFRS in Nigeria from the perspective of stakeholders. It presents the results from a questionnaire survey of a sample of accounting lecturers, auditors and accountants. The data were analyzed using the Chi Square. The study found that International Financial Reporting Standards have the potential for yielding greater benefits than current GAAP, improve business performance management and impact on other business functions apart from financial reporting. The study also finds that IFRS adoption will add to financial reporting complexities and increase compliance with accounting standards. The study recommends that management should start making comprehensive plans ahead of IFRS adoption

    Investors Assessment of the Credibility of Management Disclosures

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    The objective of this study, is to examine the issue of the assessment of the credibility of management disclosures about a company from the perspective of the investors. It presents the results from a questionnaire survey of a sample of financial Analysts, accountants and other investor. The data were analyzed using the one way analysis of variance (ANOVA). The study found that management situational incentives, internal and external assurance and other characteristics of the disclosure itself, were the factors investors considered to affect the credibility of management Disclosures. The study recommends that investors should take these factors into consideration when assessing management disclosures. The study also recommends that management should also take these factors into consideration when preparing their disclosures if they want to improve on their credibility

    Theory of the cold collision frequency shift in 1S--2S spectroscopy of Bose-Einstein-condensed and non-condensed hydrogen

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    We show that a correct formulation of the cold collision frequency shift for two photon spectroscopy of Bose-condensed and cold non-Bose-condensed hydrogen is consistent with experimental data. Our treatment includes transport and inhomogeneity into the theory of a non-condensed gas, which causes substantial changes in the cold collision frequency shift for the ordinary thermal gas, as a result of the very high frequency (3.9kHz) of transverse trap mode. For the condensed gas, we find substantial corrections arise from the inclusion of quasiparticles, whose number is very large because of the very low frequency (10.2Hz) of the longitudinal trap mode. These two effects together account for the apparent absence of a "factor of two" between the two possibilities. Our treatment considers only the Doppler-free measurements, but could be extended to Doppler-sensitive measurements. For Bose-condensed hydrogen, we predict a characteristic "foot" extending into higher detunings than can arise from the condensate alone, as a result of a correct treatment of the statistics of thermal quasiparticles.Comment: 16 page J Phys B format plus 6 postscript figure
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