The lymphatic system returns interstitial fluid back to the blood circulation. They have a network of vessels with numerous lymphangions, the segment of lymphatic vessel between two unidirectional valves. The valves aid in transporting lymph against a pressure gradient, in addition to the lymphangion pump which exhibit cyclical variations in diameter. Like blood vessels, baseline lymphatic tone is regulated with changes in transmural pressure; however, the transient response of lymphatic diastolic diameter following changes in transmural pressure has not been studied. The lymphangion pump is often described using cardiac analogies. However, since an active system empties into another active system in a lymphatic vessel, the analogy cannot characterize the principles governing optimal lymphatic vessel function. Furthermore, to optimize lymph flow there is also a need to characterize the lymphatic network structure. To characterize the transient diameter response of lymphatic segment, we used post-nodal bovine mesenteric lymphangions in an isobaric preparation and measured the diameter response to a step change in pressure. An immediate active reduction in enddiastolic diameter with each incremental increase in pressure was observed. To identify the principles governing optimal lymphatic vessel function, we applied the result obtained from optimizing the interaction of the heart-arterial system to measured lymphangion pressure-volume relationships. We assumed that the slope of end systolic pressure-volume relationship (Emax) is equal to the slope of end-diastolic relationship (Emin) above a cutoff pressure and Emax>Emin below the cutoff pressure. Unlike the heart, we found that stroke work is not optimized when Emax = Emin. However, there is a region where lymph flow is insensitive to changes in transmural pressure. To characterize the lymphatic network structure, we used an approximation of time-varying elastance model. We found there is an optimal length for the lymphangion when it produces maximal flow. To develop a fractal network model, we determined the ratio of radius and ratio of length of lymphangion at a confluence. Using conservation of mass and certain simplifying assumptions, we showed that the ratio of radius, as well as ratio of length of upstream lymphangion, to the downstream lymphangion at confluences is 1.26.

This study investigated the basic biology as well as vital statistics of the Sakura shrimp, Sergia lucens in the southwestern coast of Taiwan. The research includes length-weight relationship, spawning season, sex ratio and Von Bertalanffy equation. All sample had found partly grown eggs. The greatest spawn in January and July. It is possible that one population in the fishing area. Analysis of Covariance(ANCOVA) on the relationship between length and weight shows that male and female has the similar growth rate; but male shrimp appeared to be heavier than female for about 0.0217 g. There are more female than male in fishing area, and the ratio increase toward large size group. The growth rate of Sergia lucens is allometric. Result from morphometric study as well as fluctuation in GSI shows that the Sergested shrimp of the southwestern Taiwan can be classified as belonging to one single population but with the possible existence of two spawning subgroups. Analysis on length frequency distribution computer package, FiSAT, showed that total mortality and natural mortality was equal to 7.86 and 5.02, respectively.

Barnacles have the longest penis length, relative to body length, among all organisms. It is common for their penis length to be several times that of their bodies¡¦. One reason is that barnacles are immobile and they rely on penis to reach mates. Thus the longer the penis the more mates there may be. How do barnacles balance mate numbers and penis cost? In this investigation, we studied the possible relationship between local densities and penis lengths of barnacles. Our goal is to explain the high intraspecific variation in penis lengths of barnacles. First, we measured the Nearest Neighbor Distance(NND) and Morphological Index (MI), both indices of local barnacle densities, of individuals of Amphibalanus amphitrite at Tainan, Tetraclita kuroshioensis at Keelung and Kenting, and Tetraclitella chinensis at Penghu. The cirrus lengths were used as indices of body sizes. A high percentage of penis length variation could not be explained by body sizes in these barnacles. In A. amphitrite and T. kuroshioensis, a positive correlation between residue penis length, i.e., after deducting the effect of body size, and MI was found. Assuming no sperm competition, we found, through simulation, that the optimal penis length, is not related to local densities, whereas in the presence of sperm competition, the longer penis length the lower fitness.In lab experiment, however, penis length of A. amphitrite was found to increase with increasing number of neighbors.Under high densities, the shell base become relatively small (high MI) and the shell becomes elongated. Investment in eggs may be limited by space available for brooding, thus more energy is available to invest in male functions. Under the assumption of no sperm competition, penis length remains the only option for effective investment. The preliminary result here suggests that the penis length of barnacles is plastic and is influenced by the local density. In Tetraclitella chinensis, no correlation between local densities and penis lengths was found; the very flat shell morphology of the species may have contributed to this phenomenon.

Background: Cellulitis is a common skin and soft-tissue infection that often recurs in some patients. Patients with presenting comorbid conditions may require hospitalization which increases the cost of treatment. However, little is known about comorbid conditions as determinants for a patient’s hospital length-of-stay. Objective: 1) To profile the characteristics of patients admitted to Ontario hospitals with a diagnosis of cellulitis according to key demographic, clinical and geographic factors; 2) To examine, among patients hospitalized with cellulitis, comorbidities as possible determinants of hospital length-of-stay. Methods: A retrospective cohort of 7863 patients was identified from the Discharge Abstract Database from April 1, 2006 to March 31, 2008. The Charlson Comorbidity Index was used to measure patients’ comorbidities. Univariate analyses were performed to describe the study population. The chi-square test was used to assess the association between categorical variables. The Kaplan-Meier product-limit method and log-rank test were used to estimate and to test the difference in the distributions of hospital lengths-of-stay between patients with and without comorbidities. Cox regression modeling was used to estimate the comorbidities’ effect on hospital length-of-stay while adjusting for confounding factors. The restricted means of lengths-of-stay were given to estimate and compare the average duration of hospitalization. The effects of specific Charlson comorbidities on hospital length-of-stay were similarly investigated. Results: Forty-six percent (3588/7863) of patients were diagnosed with Charlson comorbidities. Those patients were significantly older (p<.0001), and more likely to be female (p=.006) and to have lower limb cellulitis (p<.001) and C. difficile infections (p<.0001), compared to patients without comorbidities. Patients with comorbidities stayed significantly longer in hospital (8.0 vs. 5.3 days, p<.0001). Comorbidities independently decreased the instantaneous discharge rate by 37% (95% CI, 34% to 40%, p<.001). Hospital lengths-of-stay increased with increasing index of comorbidity. The means of hospital lengths-of-stay for patients with a cumulative index of 1, 2, 3, and 4 (or more than 4) were 7.4, 7.6, 8.8, and 9.7 days, respectively. Conclusion: The Charlson Comorbidity Index is predictive of longer hospital lengths-of-stay in adult patients diagnosed with cellulitis and may be a useful tool in the decision-making process during clinical management of these patients. / Thesis (Master, Community Health & Epidemiology) -- Queen's University, 2009-11-18 11:43:07.897

Thesis (M.H.A.)--University of Michigan, 1968.

Thesis (M.H.A.)--University of Michigan, 1968. / eContent provider-neutral record in process. Description based on print version record.

Thesis (M.S.)--University of Wisconsin--Madison, 1969. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Expansion Deflection (ED) nozzles have long been considered as an alternative to conventional bell and conical designs. The ED nozzle has two primary benefits over such nozzle configurations, being shorter, and with the potential for altitude compensation. However, the difficulties involved with modelling the complex flow interactions within the nozzle type have thus far prevented the creation of a reliable method for its design and analysis. The work presented within this dissertation makes use of a combination of several different approaches to flow solution to provide a more complete analysis than previously achieved. The primary advance is the use of a CFD scheme to analyse the transonic throat region, the results of which are used as input to a Method of Characteristics based algorithm for the solution of the inviscid supersonic flow-field. This method is both efficient, and allows contour optimisation through the calculus of variations. The viscous flow region is treated in a partially or fully empirical manner, depending upon ambient pressure. The results of this analysis reveal several previously unidentified flow-field behaviours and design parameter interactions. Careful selection of the variables used to define the throat region is shown to be of considerable importance, as they effect not just the thrust produced, but also whether a real flow through such a nozzle may' exist. Secondly, the high probability of shock wave formation and interaction with the nozzle wall within length optimised ED nozzles is demonstrated. This has consequences for both the design and analysis of the ED nozzle. Overall, a framework is established which allows the flow behaviour and performance characteristics of the nozzle type to be estimated in greater detail than previously possible. The performance increments demonstrated over conventional bell nozzles include an approximately 25 to 50 percent length reduction for nozzles designed for solely high altitude operation, and a similar reduction in length plus a noticeable increase in low altitude thrust for trans-atmospheric nozzles. However, before application of the ED nozzle concept to a real system becomes possible, several areas of uncertainty must be addressed, and these are highlighted at the end of this dissertation.

In studying natural history of a disease, incident studies provide the best quality estimates; in contrast, prevalent studies introduce a sampling bias, which, if the onset time of the disease follows a stationary Poisson process, is called length bias. When both types of data are available, combining the samples under the assumption that failure times in incident and prevalent cohorts come from the same distribution function, could improve the estimation process from a revalent sample. We verify this assumption using a Smirnov type of test and construct a likelihood function from a combined sample to parametrically estimate the survival through maximum likelihood approach. Finally, we use Accelerated Failure Time models to compare the effect of covariates on survival in incident, prevalent, and combined populations. Properties of the proposed test and the combined estimator are assessed using simulations, and illustrated with data from the Canadian Study of Health and Aging.

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