Spread of Infectious Diseases with a Latent Period

Infectious diseases spread through human networks. Susceptible-Infected-Removed (SIR) model is one of the epidemic models to describe infection dynamics on a complex network connecting individuals. In the metapopulation SIR model, each node represents a population (group) which has many individuals. In this paper, we propose a modified metapopulation SIR model in which a latent period is taken into account. We call it SIIR model. We divide the infection period into two stages: an infected stage, which is the same as the previous model, and a seriously ill stage, in which individuals are infected and cannot move to the other populations. The two infectious stages in our modified metapopulation SIR model produce a discontinuous final size distribution. Individuals in the infected stage spread the disease like individuals in the seriously ill stage and never recover directly, which makes an effective recovery rate smaller than the given recovery rate.Comment: 6 pages, 3 figure

Evidence-based medicine and values-based medicine : partners in clinical education as well as in clinical practice

The best clinical decisions are based on both evidence and values in what is known as the ‘twofeet principle’. Anecdotally, educationalists find teaching clinicians to become more evidence based is relatively simple in comparison to encouraging them to become more values based. One reason is likely to be the importance of values awareness. As valuesbased practice is premised on a mutual respect for the diversity of values, clinicians need to develop the skills to ascertain patient values and to get in touch with their own beliefs and preferences in order to understand those at play in any consultation. Only then can shared decision-making processes take place within a shared framework of values. In a research article published in BMC Medicine, AltamiranoBustamante and colleagues highlight difficulties that clinicians face in getting in touch with their own values. Despite finding that healthcare personnel’s core values were honesty and respect, autonomy was initially low ranked by participants. One significant aspect of this work is that this group has demonstrated that the extent to which clinicians value ‘autonomy’ and ‘openness to change’ can both be positively influenced by well designed education

Refurbish or Replace: Optimizing Refurbished and New Building Designs for Life Cycle Carbon Footprint and Life Cycle Cost Minimisation

The refurbishments and replacements of existing buildings can significantly contribute to CO2 emissions reductions in the built environment. This paper presents and tests a novel approach for supporting the decision-making process in assessing the performance of refurbished buildings and their replacements, to achieve life-cycle CO2 emissions reductions in the most economically viable way. The proposed method, incorporating generative design scripting, dynamic thermal simulations and Genetic Algorithms optimsiation, successfully identified a set of pareto-optimal models, which achieved minimal life cycle carbon footprint and a minimal cost. Findings indicate that optimal refurbishments can achieve between 7-38% lower CO2 emissions, over an assumed life span of 60 years, and cost between 5-20% less than optimal replacements

Integrated Building Performance Optimisation: Coupling Thermal Simulation Optimisation And Generative Spatial Design Programming

The evaluation of building performance is currently implemented through the modelling and simulation of buildings, where often a single model is built and assessed based on user-generated building design inputs. Although recently developed parametric design and optimisation applications enable researchers and practitioners to automate the iteration and evaluation of building design alternatives, the integration of automatic spatial arrangement generators into the framework of these applications is still very limited. This study aims to examine the potential coupling of parametric thermal simulations and optimisations with automated generative spatial design programming, in order to incorporate different spatial arrangements as an independent simulation parameter. For this, a generative spatial arrangement algorithm was developed, and a parametric optimisation analysis was carried out. Results show that the proposed algorithm successfully automated the generation of numerous floor layouts, and the optimisation has identified a series of optimal design alternatives. This method can help decision makers to explore a significantly wider range of possible design solutions, and offer design teams optimal designs

A pentapeptide as minimal antigenic determinant for MHC class I-restricted T lymphocytes

Peptides that are antigenic for T lymphocytes are ligands for two receptors, the class I or II glycoproteins that are encoded by genes in the major histocompatibility complex, and the idiotypic / chain T-cell antigen receptor1–9. That a peptide must bind to an MHC molecule to interact with a T-cell antigen receptor is the molecular basis of the MHC restriction of antigen-recognition by T lymphocytes10,11. In such a trimolecular interaction the amino-acid sequence of the peptide must specify the contact with both receptors: agretope residues bind to the MHC receptor and epitope residues bind to the T-cell antigen receptor12,13. From a compilation of known antigenic peptides, two algorithms have been proposed to predict antigenic sites in proteins. One algorithm uses linear motifs in the sequence14, whereas the other considers peptide conformation and predicts antigenicity for amphipathic -helices15,16. We report here that a systematic delimitation of an antigenic site precisely identifies a predicted pentapeptide motif as the minimal antigenic determinant presented by a class I MHC molecule and recognized by a cytolytic T lymphocyte clone

Increasing confidence and changing behaviors in primary care providers engaged in genetic counselling.

BackgroundScreening and counseling for genetic conditions is an increasingly important part of primary care practice, particularly given the paucity of genetic counselors in the United States. However, primary care physicians (PCPs) often have an inadequate understanding of evidence-based screening; communication approaches that encourage shared decision-making; ethical, legal, and social implication (ELSI) issues related to screening for genetic mutations; and the basics of clinical genetics. This study explored whether an interactive, web-based genetics curriculum directed at PCPs in non-academic primary care settings was superior at changing practice knowledge, attitudes, and behaviors when compared to a traditional educational approach, particularly when discussing common genetic conditions.MethodsOne hundred twenty one PCPs in California and Pennsylvania physician practices were randomized to either an Intervention Group (IG) or Control Group (CG). IG physicians completed a 6 h interactive web-based curriculum covering communication skills, basics of genetic testing, risk assessment, ELSI issues and practice behaviors. CG physicians were provided with a traditional approach to Continuing Medical Education (CME) (clinical review articles) offering equivalent information.ResultsPCPs in the Intervention Group showed greater increases in knowledge compared to the Control Group. Intervention PCPs were also more satisfied with the educational materials, and more confident in their genetics knowledge and skills compared to those receiving traditional CME materials. Intervention PCPs felt that the web-based curriculum covered medical management, genetics, and ELSI issues significantly better than did the Control Group, and in comparison with traditional curricula. The Intervention Group felt the online tools offered several advantages, and engaged in better shared decision making with standardized patients, however, there was no difference in behavior change between groups with regard to increases in ELSI discussions between PCPs and patients.ConclusionWhile our intervention was deemed more enjoyable, demonstrated significant factual learning and retention, and increased shared decision making practices, there were few differences in behavior changes around ELSI discussions. Unfortunately, barriers to implementing behavior change in clinical genetics is not unique to our intervention. Perhaps the missing element is that busy physicians need systems-level support to engage in meaningful discussions around genetics issues. The next step in promoting active engagement between doctors and patients may be to put into place the tools needed for PCPs to easily access the materials they need at the point-of-care to engage in joint discussions around clinical genetics

A survey of statistics in three UK general practice journal

Background Many medical specialities have reviewed the statistical content of their journals. To our knowledge this has not been done in general practice. Given the main role of a general practitioner as a diagnostician we thought it would be of interest to see whether the statistical methods reported reflect the diagnostic process. Methods Hand search of three UK journals of general practice namely the British Medical Journal (general practice section), British Journal of General Practice and Family Practice over a one-year period (1 January to 31 December 2000). Results A wide variety of statistical techniques were used. The most common methods included t-tests and Chi-squared tests. There were few articles reporting likelihood ratios and other useful diagnostic methods. There was evidence that the journals with the more thorough statistical review process reported a more complex and wider variety of statistical techniques. Conclusions The BMJ had a wider range and greater diversity of statistical methods than the other two journals. However, in all three journals there was a dearth of papers reflecting the diagnostic process. Across all three journals there were relatively few papers describing randomised controlled trials thus recognising the difficulty of implementing this design in general practice

Selling Health Promotion to Corporate America: Uses and Abuses of the Economic Argument

Economic considerations constitute a significant factor in businesses' interest in adopting health promotion (HP) programs and in the wellness community's attempts to sell such programming to business. Substantial elements of both the business and wellness communities believe that HP programs are financially profitable, in addition to, and as a result of, improving employees' health. Examination of the foundation of this belief, however, leads to the conclusion that underlying analyses have been techni cally flawed and have ignored important costs of HP programs. This article discusses the limitations of these analyses and outlines the framework of a model that could provide a sound assessment of the economics of workplace HP programs. In general, it is expected that resultant analyses would find less direct profit potential in work place HP programs but would emphasize the cost-effectiveness of many such efforts. The latter would force recognition that health, and not profit, is the principal benefit of health promotion programming. The distinction between the cost-effectiveness and cost-saving potential of health promotion is one that all interested parties should master.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66785/2/10.1177_109019818701400106.pd

Synchronized dynamics of cortical neurons with time-delay feedback

The dynamics of three mutually coupled cortical neurons with time delays in the coupling are explored numerically and analytically. The neurons are coupled in a line, with the middle neuron sending a somewhat stronger projection to the outer neurons than the feedback it receives, to model for instance the relay of a signal from primary to higher cortical areas. For a given coupling architecture, the delays introduce correlations in the time series at the time-scale of the delay. It was found that the middle neuron leads the outer ones by the delay time, while the outer neurons are synchronized with zero lag times. Synchronization is found to be highly dependent on the synaptic time constant, with faster synapses increasing both the degree of synchronization and the firing rate. Analysis shows that presynaptic input during the interspike interval stabilizes the synchronous state, even for arbitrarily weak coupling, and independent of the initial phase. The finding may be of significance to synchronization of large groups of cells in the cortex that are spatially distanced from each other.Comment: 21 pages, 11 figure