Time evolution of the Partridge-Barton Model

The time evolution of the Partridge-Barton model in the presence of the pleiotropic constraint and deleterious somatic mutations is exactly solved for arbitrary fecundity in the context of a matricial formalism. Analytical expressions for the time dependence of the mean survival probabilities are derived. Using the fact that the asymptotic behavior for large time $t$ is controlled by the largest matrix eigenvalue, we obtain the steady state values for the mean survival probabilities and the Malthusian growth exponent. The mean age of the population exhibits a $t^{-1}$ power law decayment. Some Monte Carlo simulations were also performed and they corroborated our theoretical results.Comment: 10 pages, Latex, 1 postscript figure, published in Phys. Rev. E 61, 5664 (2000

Plant virus infections control stomatal development

Stomata are important regulators of carbon dioxide uptake and transpirational water loss. They also represent points of vulnerability as bacterial and fungal pathogens utilise this natural opening as an entry portal, and thus have an increasingly complex relationship. Unlike the situation with bacterial and fungal pathogens, we know very little about the role of stomata in viral infection. Here we report findings showing that viral infection influences stomatal development in two susceptible host systems (Nicotiana tabacum with TMV (Tobacco mosaic virus), and Arabidopsis thaliana with TVCV (Turnip vein-clearing virus)), but not in resistant host systems (Nicotiana glutinosa and Chenopodium quinoa with TMV). Virus infected plants had significantly lower stomatal indices in systemic leaves of susceptible systems; N. tabacum 9.8% reduction and A. thaliana 12.3% reduction, but not in the resistant hosts. Stomatal density in systemic leaves was also significantly reduced in virus infected A. thaliana by 19.6% but not in N. tabacum or the resistant systems. In addition, transpiration rate was significantly reduced in TMV infected N. tabacum

The Impact of Demographic, Social, and Environmental Factors on the Development of Steroid-Responsive Meningitis-Arteritis (SRMA) in the United Kingdom

BACKGROUND: Steroid‐responsive meningitis‐arteritis (SRMA) is an inflammatory disease of dogs that is suspected to be immune‐mediated. The development of other immune‐mediated diseases has been linked to vaccinations, time of the year, geographic location, sex, neuter status, and breed. HYPOTHESIS/OBJECTIVES: To identify if the development of SRMA is associated with time of year, vaccination, geographic location, sex, neuter status, and breed. ANIMALS: Sixty SRMA cases and 180 controls, all ≤24 months of age and matched for year of presentation, from a referral hospital population in the United Kingdom. METHODS: Retrospective case‐control study with unconditional logistic regression analysis. RESULTS: Beagles (P = .001), Border Collies (P = .001), Boxers (P = .032), Jack Russell Terriers (P = .001), Weimaraners (P = .048), and Whippets (P < .001) had significantly greater odds of developing SRMA in this population of dogs. Vaccination, time of year, geographic category, sex, and neuter status did not increase the odds of developing SRMA. CONCLUSIONS AND CLINICAL IMPORTANCE: Only breed increased the odds of developing SRMA. It would be prudent to investigate the genetics of the identified breeds to help elucidate the etiopathogenesis of SRMA

Accreditation council for graduate medical education (ACGME) annual anesthesiology residency and fellowship program review: a "report card" model for continuous improvement

<p>Abstract</p> <p>Background</p> <p>The Accreditation Council for Graduate Medical Education (ACGME) requires an annual evaluation of all ACGME-accredited residency and fellowship programs to assess program quality. The results of this evaluation must be used to improve the program. This manuscript describes a metric to be used in conducting ACGME-mandated annual program review of ACGME-accredited anesthesiology residencies and fellowships.</p> <p>Methods</p> <p>A variety of metrics to assess anesthesiology residency and fellowship programs are identified by the authors through literature review and considered for use in constructing a program "report card."</p> <p>Results</p> <p>Metrics used to assess program quality include success in achieving American Board of Anesthesiology (ABA) certification, performance on the annual ABA/American Society of Anesthesiology In-Training Examination, performance on mock oral ABA certification examinations, trainee scholarly activities (publications and presentations), accreditation site visit and internal review results, ACGME and alumni survey results, National Resident Matching Program (NRMP) results, exit interview feedback, diversity data and extensive program/rotation/faculty/curriculum evaluations by trainees and faculty. The results are used to construct a "report card" that provides a high-level review of program performance and can be used in a continuous quality improvement process.</p> <p>Conclusions</p> <p>An annual program review is required to assess all ACGME-accredited residency and fellowship programs to monitor and improve program quality. We describe an annual review process based on metrics that can be used to focus attention on areas for improvement and track program performance year-to-year. A "report card" format is described as a high-level tool to track educational outcomes.</p

Using solution history to control hydrogel properties of a perylene bisimide

pH dependence on water soluble aggregates is well-known in the field of low molecular weight gelators (LMWGs), with different aggregates sometimes having very different properties depending on their final pH. This aggregation determines their applications and performance. Here, we investigate the pH dependence of perylene bisimide gels; initially solutions are formed at a high pH and gels form as the pH is decreased. We find it is not only the final pH but also the starting pH that can impact the resulting gel. We use small angle neutron scattering (SANS), rheology, 1H NMR spectroscopy and absorption spectroscopy to examine the effect of starting pH on gelation kinetics and final gel properties. Adjusting the solution from pH 9 (where there are few or no aggregates) to pH 6 results in the formation of different worm-like micelles than the ones directly formed at pH 6, leading to again gels with different mechanical properties. This work highlights the importance of controlling the pH of solutions before gelation, but also opens up more possible morphologies and therefore more properties from the same molecule

Why growth equals power - and why it shouldn't : constructing visions of China

When discussing the success of China's transition from socialism, there is a tendency to focus on growth figures as an indication of performance. Whilst these figures are indeed impressive, we should not confuse growth with development and assume that the former necessarily automatically generates the latter. Much has been done to reduce poverty in China, but the task is not as complete as some observers would suggest; particularly in terms of access to health, education and welfare, and also in dealing with relative (rather than absolute) depravation and poverty. Visions of China have been constructed that exaggerate Chinese development and power in the global system partly to serve political interests, but partly due to the failure to consider the relationship between growth and development, partly due to the failure to disaggregate who gets what in China, and partly due to the persistence of inter-national conceptions of globalised production, trade, and financial flows

‘Doing’ health policy analysis: methodological and conceptual reflections and challenges

The case for undertaking policy analysis has been made by a number of scholars and practitioners. However, there has been much less attention given to how to do policy analysis, what research designs, theories or methods best inform policy analysis. This paper begins by looking at the health policy environment, and some of the challenges to researching this highly complex phenomenon. It focuses on research in middle and low income countries, drawing on some of the frameworks and theories, methodologies and designs that can be used in health policy analysis, giving examples from recent studies. The implications of case studies and of temporality in research design are explored. Attention is drawn to the roles of the policy researcher and the importance of reflexivity and researcher positionality in the research process. The final section explores ways of advancing the field of health policy analysis with recommendations on theory, methodology and researcher reflexivity