A mathematical model of steady state B lymphopoiesis in mouse and rat bone marrow /

In this study, we have analyzed the steady-state kinetics of B lymphocytes in mouse and rat bone marrow using previously published experimental data. Over many years, Prof D.G. Osmond and his colleagues have built up a scheme of B cell development in mouse bone marrow based on the sequential expression of markers associated with the B lineage. The earliest precursor B cells comprise three populations of proliferating pro-B cells, i.e. early, intermediate, and late pro-B cells. The subsequent populations comprise pre-B cells that give rise to nondividing B lymphocytes expressing surface IgM.In our analysis, we have checked the available published data for consistency with the proliferation of precursor B cells and their death via apoptosis at certain stages of cell development. We made an extensive summary of the existing data on the various B cell precursors and organized it into a comprehensible framework. We built a mathematical model for the proliferation and differentiation of mammalian B lymphocytes in laboratory mice and rats and estimated all of the parameters to explain the existing steady state data. In this context, mathematical modeling acts as a useful tool to analyze hypotheses and experimental results concerning the steady state numbers of B lymphocytes

DETERMİNATİON OF SOME CHEMİCALS and MİCROBİOLOGİCAL CHARACTERISTIC OF KASTAMONU ÇEKME HALVA

Bu çalışma Kastamonu ilinde üretilen farklı firmalara ait 10 farklı çeşit çekme helva ürünlerinin kimyasal ve mikrobiyolojik özelliklerinin belirlenmesi amacıyla yapılmıştır. Fabrikalarda endüstriyel olarak üretilmiş ürünlerden alınan numuneler kullanılmış ve referans olarak TSE 13028 Çekme Helva standardı baz alınmıştır. Genel olarak numunelerin tamamında kimyasal analiz sonuçlarından nem, kül,ve toplam şeker miktarları atıf yapılan standartta belirtilen değerlerin altında çıkmıştır. Ancak yağ miktarı ise standartta belirtilen değerin bir miktar üzerinde çıkmıştır. Bu fazlalık duyusal açıdan üründe herhangi bir kusur yaratmadığı için önemsenmeyecek değer olarak göze çarpmıştır. Tüm bu kimyasal analizlerde ortalama değerler esas alındığında yağ oranındaki küçük farklılık dışında hepsi literatüre uygun çıkmıştır. Yine aynı şekilde mikrobiyolojik analiz sonuçları da standartta öngörülen maksimum kabul edilebilir limit değerlerin altında çıkmıştır. Ürünün mikrobiyolojik açıdan kalitesinin yüksekliği gelişmiş ambalajlama tekniklerinin kullanılması, ambalajlama ve depolama koşullarında hijyen kurallarına uyulması sonucu gelişme göstermiştir. Çekme helva ürünün pazar payının artması, ihracatının yükselmesi, üretimi yapılan firmalarda geleneksel yöntemler yerine ileri teknoloji kullanılarak standart ve daha hijyenik ürünlerin üretilmesi ile artış göstermektedir.This study was carried out in order to determine the physical and chemical properties of 10 types of products belonging to different firms in the province of Kastamonu. Samples from industrially produced products were used and reference was made to TSE 13028 Çekme Halva Standard. In general, the total amount of moisture, ash, and total sugar from the chemical analysis results was below the standard values quoted in the standard. However, the amount of fat has exceeded the amount specified in the standard. This surplus is not sensible in the sense that it does not cause any defects, so the value is negligible. All of these chemical analyzes were based on the average values, except for the small difference in the fat ratio. Likewise, microbiological analysis results were below the maximum acceptable limit values stipulated in the standard. The microbiological quality of the product has improved after the use of advanced packaging techniques, compliance with hygiene rules in packaging and storage conditions. Increasing market share of pulling halva products, increasing exporting companies are increasing with the production of standard and more hygienic products by using advanced technology instead of traditional methods

Why clinical practice guidelines shift over time : a dynamic model with application to prostate cancer screening

Thesis: Ph. D., Massachusetts Institute of Technology, Sloan School of Management, 2016.Cataloged from PDF version of thesis.Includes bibliographical references.Essay 1: A Dynamic Model for Understanding Long-Term Trends in Prostate Cancer Screening Cancer remains the second leading cause of death in the U.S. after heart disease. After 35 years of routine cancer screening, we still have only a limited understanding of screening dynamics. There is evidence of over-screening and resulting overtreatment in certain cases, and significant provider variation and fluctuations over time in screening criteria. Here I present empirical data for fluctuations in official screening guidelines and in actual practice for the use of the prostate-specific antigen (PSA) test. I explore how these dynamics are affected by the main guideline-issuing organizations in the U.S. and by clinicians, patient groups, and the media. Essay 2: Our Walk to the End of Cancer? Understanding Long-Term Trends in Medical Screening In this study we develop the first integrated, broad boundary feedback theory and formal model to explain the dynamics of medical screening. The theory includes a decision-theoretic core around harms and benefits including the fundamental tradeoff between sensitivity and specificity; and feedbacks that condition guidelines and actual practice. To provide context we use the case of PSA screening for prostate cancer as a motivating example, but our model is generic and applicable to other contexts. We present a behaviorally realistic, boundedly-rational model of detection and selection for health screening that creates oscillations in policy recommendation thresholds of formal guidelines. This core model, entailing only the evidence generation and translation processes, demonstrates how oscillations are natural to this category of problems due to inherent delays in evidence-based screening. These fluctuations lead to long periods during which screening guidelines are suboptimal. Essay 3: A Dynamic Model for Understanding Long-Term Trends in Prostate Cancer Screening Whereas guidelines for routine screening should be based on medical evidence, evidence often has relatively little impact on practice. This situation has led to ongoing controversy and conflict over appropriate guidelines among scientists, clinicians, and patient advocacy groups. There are significant variations in clinical practice, including evidence of over-screening for some diseases, and under-screening for others. To explain the patterns of over-screening, fluctuations, low adherence to guidelines, and conflict, I develop the first explicit broad boundary feedback theory of the dynamics of medical screening, tested in a formal mathematical model. The model presents an extended case study specific to PSA screening for prostate cancer, including realistic presentations for the fundamental tradeoff between test sensitivity and specificity, the natural progression of the disease, and respective changes in population size and composition.by Özge Karanfil.A dynamic model for understanding long-term trends in prostate cancer screening -- Our walk to the end of cancer?: understanding long-term trends in medical screening -- A dynamic model for understanding long-term trends in prostate cancer screening.S.M. in Management Researc

Sandia National Laboratories Complex Adaptive Infrastructures and Behavioral Systems

Complex adaptive systems-of-systems are inherently multi-scale across several dimensions, including temporal, geographical, and organizational. We present a multi-model paradigm integrating a community-scale individual-based model (IBM) to investigate the immediate effects of interventions with a population-scale system dynamics (SD) model to analyze longterm results of those interventions. The IBM incorporates actors embedded in a social network to simulate the spread of opinions relating to nutrition and physical activity (N&PA) behaviors such as dieting and exercise, and the effects of these opinions on individual actions and consequential body weights. The IBM network structure is composed of a mixture of scale-free and uniformly random connections to represent a social network of relationships and interactions within a community: opinions regarding obesogenic behaviors propagate among individuals on the network, or are influenced by media sources via advertising, public health campaigns, and counter-marketing. We analyze and compare effects of possible policy interventions, and illustrate a policy cocktail that addresses multiple aspects of the obesity problem, resulting in amplification of desirable results and a strong uncertainty reduction. The outputs of the IBM, seen as changes in obesogenic behaviors, are used by the SD model to calculate the resulting changes in mortality and morbidity over ensuing decades