Methods for computing the standard errors of branching points in an evolutionary tree and their application to molecular data from humans and apes

Statistical methods for computing the standard errors of the branching points of an evolutionary tree are developed. These methods are for the unweighted pair-group method-determined (UPGMA) trees reconstructed from molecular data such as amino acid sequences, nucleotide sequences, restriction-sites data, and electrophoretic distances. They were applied to data for the human, chimpanzee, gorilla, orangutan, and gibbon species. Among the four different sets of data used, DNA sequences for an 895-nucleotide segment of mitochondrial DNA (Brown et al. 1982) gave the most reliable tree, whereas electrophoretic data (Bruce and Ayala 1979) gave the least reliable one. The DNA sequence data suggested that the chimpanzee is the closest and that the gorilla is the next closest to the human species. The orangutan and gibbon are more distantly related to man than is the gorilla. This topology of the tree is in agreement with that for the tree obtained from chromosomal studies and DNA-hybridization experiments. However, the difference between the branching point for the human and the chimpanzee species and that for the gorilla species and the human-chimpanzee group is not statistically significant. In addition to this analysis, various factors that affect the accuracy of an estimated tree are discussed.      

Modeling of experiments on biofilm penetration effects in a fluidized bed nitrification reactor

A four-component, diffusion-reaction model with double Michaelis-Menten kinetics was used to describe the experimental data obtained from a laboratory biofilm, fluidized-bed nitrification reactor. Theory and experiment demonstrated that the stoichiometric ratio (3.5 mg O(2)/mg NH(4) (+)-N) can be employed as a criterion to determine whether the limiting substrate is oxygen or ammonia. For the present work, in the range of concentrations where limitation occurred, 4 mg/L NH(4) (+)-N and 14 mg/L O(2), the ratio of oxygen to ammonia in the bulk liquid determined which substrate was penetration-limiting-O(2) if <3.5 and NH(4) (+) if > 3.5. Halforder kinetics with respect to the limiting substrate described the apparent overall rates. Simulations provided biofilm concentration profiles which demonstrated the role of the oxygen-ammonia ratio. Experiments indicated that, generally, high NO(2) (-) concentrations can be expected. These depend on the residence time, biofilm area, and oxygen concentration. This dependency was investigated with the model, as was the parametric sensitivity with respect to the saturation constants. Particularly important for the NO(2) (-) levels were the ratios of the saturation constants for oxygen.     

Ataxia-Telangiectasia

Ataxia-telangiectasia is a syndrome of progressive cerebellar ataxia and other neurological manifestations associated with conjunctival and cutaneous telangiectases and with recurrent sino-pulmonary infections. Immunological and endocrine abnormalities occur. Two girls with this disease are described. The first had only minor respiratory infections; her serum proteins and immunity responses appeared normal. The second had recurrent pulmonary infections and bronchiectasis; she also exhibited sclerodermatous changes, poor development of secondary sexual characteristics with low urinary excretion of 17-ketosteroids, and lymphopenia. Autopsy at 17 years showed bilateral ovarian dysgerminomata and excessive cutaneous collagen as well as atrophy, and perhaps hypoplasia, of adrenals, thymus, spleen and lymphoid tissue (after steroid therapy). The cerebellum exhibited cortical degeneration. Both lungs were fibrotic with old and recent bronchopneumonia and bronchiectasis. The left lung was studied by injection of a latex preparation; no arteriovenous aneurysms were found, but the smaller pulmonary vessels showed some unusual morphological characteristics.     

Production planning of a flexible manufacturing system in a material requirements planning environment

Early flexible manufacturing system (FMS) production planning models exhibited a variety of planning objectives; typically, these objectives were independent of the overall production environment. More recently, some researchers have proposed hierarchical production planning and scheduling models for FMS. In this article, we examine production planning of FMS in a material requirements planning (MRP) environment. We propose a hierarchical structure that integrates FMS production planning into a closed-loop MRP system. This structure gives rise to the FMS/MRP rough-cut capacity planning (FMRCP) problem, the FMS/MRP grouping and loading (FMGL) problem, and the FMS/MRP detailed scheduling problem. We examine the FMRCP and FMGL problems in detail and present mathematical programming models for each of these problems. In particular, the FMRCP problem is modeled as a generalized assignment problem (GAP), and a GAP-based heuristic procedure is defined for the problem. We define a two-phase heuristic for the FMGL problem and present computational experience with both heuristics. The FMRCP heuristic is shown to solve problems that exhibit a dependent-demand relation within the FMS and with FMS capacity utilization as high as 99 percent. The FMGL heuristic requires very little CPU time and obtains solutions to the test problems that are on average within 1.5 percent of a theoretical lower bound. This FMS/MRP production planning framework, together with the resulting models, constitutes an important step in the integration of FMS technology with MRP production planning. The hierarchical planning mechanism directly provides for system-level MRP planning priorities to induce appropriate production planning and control objectives on the FMS while simultaneously allowing for necessary feedback from the FMS. Moreover, by demonstrating the tractability of the FMRCP and FMGL problems, this research establishes the necessary groundwork upon which to explore systemwide issues pertaining to the coordination of the hierarchical structure.     

Respiratory epithelial permeability after cigarette smoke exposure in guinea pigs

The purpose of this study was to determine the pathology of cigarette smoke-increased permeability at the bronchioalveolar junction of the guinea pig. After exposure to either smoke or room air, guinea pigs were anesthetized and fluorescein isothiocyanate-dextran (FITC-D, mol wt 10,000) was aerosolized into their lungs. Blood samples taken through a carotid arterial cannula were analyzed by gel chromatography and spectrofluorometry for the presence of FITC-D. The results confirmed that, after smoke exposure, increased amounts of intact FITC-D molecules with a reported Einstein-Stokes radius of 22.2 A crossed the respiratory epithelium into the vascular space. Transmission electron-microscopic studies showed that the FITC-D diffused across damaged type I pneumocyte membranes and cytoplasm to reach the basal lamina and entered the alveolar capillaries through endothelial tight junctions. Damage to the alveolar epithelium was more frequent for the smoke-exposed animals than the room air-exposed animals (P less than 0.05). We conclude that smoke exposure damages type I cells and that inhaled FITC-D crosses the epithelial barrier at damaged type I cells of the bronchioloalveolar junctions.