712 research outputs found

    Addendum: Attenuation of the intensity within a superdeformed band

    Full text link
    We investigate a random matrix model [Phys. Rev. C {\bf 65} 024302 (2002] for the decay-out of a superdeformed band as a function of the parameters: Γ↓/ΓS\Gamma^\downarrow/\Gamma_S, ΓN/D\Gamma_N/D, ΓS/D\Gamma_S/D and Δ/D\Delta/D. Here Γ↓\Gamma^\downarrow is the spreading width for the mixing of an SD state ∣0>|0> with a normally deformed (ND) doorway state ∣d>|d>, ΓS\Gamma_S and ΓN\Gamma_N are the electromagnetic widths of the the SD and ND states respectively, DD is the mean level spacing of the compound ND states and Δ\Delta is the energy difference between ∣0>|0> and ∣d>|d>. The maximum possible effect of an order-chaos transition is inferred from analytical and numerical calculations of the decay intensity in the limiting cases for which the ND states obey Poisson and GOE statistics. Our results show that the sharp attenuation of the decay intensity cannot be explained solely by an order-chaos transition.Comment: 4 pages, 4 figures, submitted to Physical Review

    Energy averages over regular and chaotic states in the decay out of superdeformed bands

    Full text link
    We describe the decay out of a superdeformed band using the methods of reaction theory. Assuming that decay-out occurs due to equal coupling (on average) to a sea of equivalent chaotic normally deformed (ND) states, we calculate the average intraband decay intensity and show that it can be written as an ``optical'' background term plus a fluctuation term, in total analogy with average nuclear cross sections. We also calculate the variance in closed form. We investigate how these objects are modified when the decay to the ND states occurs via an ND doorway and the ND states' statistical properties are changed from chaotic to regular. We show that the average decay intensity depends on two dimensionless variables in the first case while in the second case, four variables enter the picture.Comment: 8 pages, 1 figure, presented at FUSION03, Matsushima, Miyagi, Japan, Nov 12-15, 2003, to appear in Progress of Theoretical Physics; corrected typo

    How large is the spreading width of a superdeformed band?

    Get PDF
    Recent models of the decay out of superdeformed bands can broadly be divided into two categories. One approach is based on the similarity between the tunneling process involved in the decay and that involved in the fusion of heavy ions, and builds on the formalism of nuclear reaction theory. The other arises from an analogy between the superdeformed decay and transport between coupled quantum dots. These models suggest conflicting values for the spreading width of the decaying superdeformed states. In this paper, the decay of superdeformed bands in the five even-even nuclei in which the SD excitation energies have been determined experimentally is considered in the framework of both approaches, and the significance of the difference in the resulting spreading widths is considered. The results of the two models are also compared to tunneling widths estimated from previous barrier height predictions and a parabolic approximation to the barrier shape

    Why are the oldest old less generous? Explanations for the unexpected age-related drop in charitable giving

    Get PDF
    ABSTRACT Previous research has demonstrated that the generally positive relationship between age and the presence of charitable giving becomes negative at the oldest ages. We investigate potential causes of this drop in charitable giving among the oldest old including changes in health, cognition, egocentric networks, religious attendance, and substitution of charitable bequest planning. A longitudinal analysis of data from the United States Health and Retirement Survey indicates that the drop in charitable giving is mediated largely by changes in the frequency of church attendance, with only modest influences from changes in health and cognition

    Exploring shared decision making in breast cancer care: A case-based conversation analytic approach

    Get PDF
    Shared decision making (SDM) is acknowledged as the gold standard of healthcare communication, particularly relevant to preference-sensitive care such as breast cancer treatment. However, research on patients’ experiences shows a misalignment between clinicians’ goals and the rhetoric regarding patients’ empowerment during SDM for this treatment. This warrants detailed examination on the conversational dynamics of SDM, and this study aims to identify interactional features and social practices through which SDM is achieved. Fifteen audio recordings from adjuvant treatment breast cancer consultations were examined using the methodology of conversation analysis (CA), and recurrent patterns relevant for understanding SDM were identified. Boundary markers, rhetorical questioning and epistemic markers discouraged a shared orientation to patient participation, reinforcing perceived imbalanced doctor–patient power relations. Cues for SDM such as multi-turn utterances and spaces for transition were presented but not recognised by patients, resulting in sub-optimal two-way discussions about decision making. The findings also reveal that interactional practices were deployed that theoretically should have enabled patients to contribute to SDM. However, in reality these did not result in extended sequences of reciprocated contributions from practitioner and service user. SDM did not happen with the ease implied by current models, and the resultant interactions bore more similarity to expert-led, rather than collaborative, decision makin

    Differences in human antagonistic ankle dorsiflexor coactivation between legs; can they explain the moment deficit in the weaker plantarflexor leg?

    Get PDF
    The present study examined the hypothesis that the antagonistic ankle dorsiflexor coactivation level during maximum isometric voluntary plantarflexion (MVC) is a function of ankle angle. Six male subjects generated plantarflexion and dorsiflexion MVC trials at ankle angles of −15 deg (dorsiflexed direction), 0 deg (neutral position), +15 deg (plantarflexed direction) and +30 deg having the knee flexed at an angle of 90 deg. In all contractions surface EMG measurements were taken from tibialis anterior and soleus which were considered representative muscles of all dorsiflexors and plantarflexors, respectively. Antagonistic dorsiflexor coactivation was expressed as normalized EMG and moment. Calculations of the antagonistic dorsiflexor moment were based on the tibialis anterior EMG—dorsiflexor moment relationship from contractions at 50, 40, 30, 20 and 10% of the dorsiflexion MVC moment. In both legs dorsiflexor coactivation level followed an open U-shaped pattern as a function of ankle angle. Differences of 9 and 14% (P < 0·05) were found in the measured net plantarflexion MVC moment between legs at ankle angles of −15 and +30 deg, respectively. No difference (P > 0·05) was found in the calf circumference between legs. Differences were found in the antagonistic dorsiflexor coactivation between legs at ankle angles of −15 and +30 deg. In the weaker leg the antagonistic EMG measurements were higher by 100 and 45% (P < 0·01) and the estimated antagonistic moments were higher by 70 and 43% (P < 0·01) compared with the weaker leg at −15 and +30 deg, respectively. This finding was associated with a decreased range of motion (ROM) in the weaker leg (14%, P < 0·01), such that no difference (P > 0·05) was found in dorsiflexor antagonistic coactivation between legs at end-range ankle angles. The findings of the study (i) have to be taken into consideration when estimating musculoskeletal loads in the lower extremity, (ii) imply that stretching training can result in a stronger plantarflexion at end-range ankle angles through inhibition of the dorsiflexors, and (iii) imply a neural drive inadequacy during a plantarflexion MVC at end-range angles

    Some Reflections on Age Discrimination, Referees’ Retirement Ages and European Sports (Law)

    Get PDF
    Introduction: This paper is the first in a series of reflections on the relationship between discrimination, sport and the law, a body of work that has been motivated in part by the potential impact of the 2000 Equalities Directive upon European sports law, but also by developments in human rights jurisprudence and in the domestic laws of several jurisdictions. The phenomenon of age discrimination in sport, and the social and economic impact thereof, has been far less widely considered than is the case with other forms of sports discrimination (although the literature would miraculously emerge if the subject-matter were more directly concerned with men’s professional football). In contrast, free movement and competition law have impacted significantly upon sports provisions that discriminate on the basis of nationality; it is equally evident that age discrimination in the context of sports employment has not been considered with anything approaching the degree of sophistication that pervades our understanding of discrimination in occupation or employment on the grounds of disability, sexual orientation and religion/belief (the other discriminatory forms that are covered by the 2000 Directive); and our poor understanding of age-related sports discrimination generally stands in marked contrast to our appreciation of how challenges to discrimination on the grounds of sex and race have precipitated far-reaching changes to sports practices. Throughout the EU, with the possible exception of the Irish Republic, age discrimination law is far less advanced than is the case with discrimination which takes any of those other forms, the remedies are weaker and fewer people are aware of them. However, this state of affairs will undoubtedly change under the impact of the Equalities Directive, and even though the provisions themselves (and member states’ transposing of them) attract legitimate criticism, some longstanding practices of sports bodies are now open to challenge

    Methods and Processes of Developing the Strengthening the Reporting of Observational Studies in Epidemiology – Veterinary (STROBE-Vet) Statement

    Get PDF
    BACKGROUND Reporting of observational studies in veterinary research presents challenges that often are not addressed in published reporting guidelines. OBJECTIVE To develop an extension of the STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) statement that addresses unique reporting requirements for observational studies in veterinary medicine related to health, production, welfare, and food safety. DESIGN Consensus meeting of experts. SETTING Mississauga, Canada. PARTICIPANTS Seventeen experts from North America, Europe, and Australia. METHODS Experts completed a pre-meeting survey about whether items in the STROBE statement should be modified or added to address unique issues related to observational studies in animal species with health, production, welfare, or food safety outcomes. During the meeting, each STROBE item was discussed to determine whether or not rewording was recommended and whether additions were warranted. Anonymous voting was used to determine consensus. RESULTS Six items required no modifications or additions. Modifications or additions were made to the STROBE items 1 (title and abstract), 3 (objectives), 5 (setting), 6 (participants), 7 (variables), 8 (data sources/measurement), 9 (bias), 10 (study size), 12 (statistical methods), 13 (participants), 14 (descriptive data), 15 (outcome data), 16 (main results), 17 (other analyses), 19 (limitations), and 22 (funding). CONCLUSION The methods and processes used were similar to those used for other extensions of the STROBE statement. The use of this STROBE statement extension should improve reporting of observational studies in veterinary research by recognizing unique features of observational studies involving food-producing and companion animals, products of animal origin, aquaculture, and wildlife
    • …
    corecore