Collision induced spatial organization of microtubules

The dynamic behavior of microtubules in solution can be strongly modified by interactions with walls or other structures. We examine here a microtubule growth model where the increase in size of the plus-end is perturbed by collisions with other microtubules. We show that such a simple mechanism of constrained growth can induce ordered structures and patterns from an initially isotropic and homogeneous suspension. First, microtubules self-organize locally in randomly oriented domains that grow and compete with each other. By imposing even a weak orientation bias, external forces like gravity or cellular boundaries may bias the domain distribution eventually leading to a macroscopic sample orientation.Comment: Submitted to Biophysical Journa

Models for Treatment of Patients with Complex Medical-Psychiatric Conditions

Patients with co-morbidity and multi-morbidity have worse outcomes and greater healthcare needs. Co-morbid depression and other long-term conditions present health services with challenges in delivering effective care for patients. We provide some recent evidence from the literature to support the need for collaborative care, illustrated by practical examples of how to deliver a collaborative/integrated care continuum by presenting data collected between 2011 and 2012 from a London Borough clinical improvement programme that compared co-morbid diagnosis of depression and other long-term conditions and Accident and Emergency use. We have provided some practical steps for developing collaborative care within primary care and suggest that primary care family practices should adopt closer collaboration with other services in order to improve clinical outcomes and cost-effectiveness.publishersversionpublishe

A study of twenty-four women who have rheumatic heart disease

Thesis (M.S.)--Boston University, 1943. This item was digitized by the Internet Archive

Random and Block Copolymers of Poly(dodecamethyleneterephthalamide)

The following dissertation focuses on the synthesis and characterization of poly(dodecamethylene terephthalamide) (PA-12,T) and novel copolymers. Chapter I details the synthesis of PA-12,T homopolymer by melt condensation polymerization. A series of homopolymers with different molecular weights were obtained by adjusting the stoichiometry of the polymerization using 1,12-diaminododecane, terephthalic acid and benzoic acid. End group 13C NMR spectroscopy resonances were obtained by correlating peak intensities with intrinsic viscosity values. From the NMR data, total end group concentrations and molecular weights were determined for each sample. The data exhibited a linear trend when plotting log (IV) versus log (Mn), and previously unknown PA-12,T Mark-Houwink solution constants were found. Chapter II examines the synthesis and characterization of PA-12,T, 6,T and 10,T, 6,T copolymers. Melt condensation procedures and solution constants from Chapter I were used to synthesize and confirm that high molecular weight copolymers were obtained. The substituted aromatic carbon resonance of 13C NMR spectra was found to be sensitive to copolymer sequence, and was used to determine that the copolymers are random. Differential scanning calorimetry data shows that the copolymers exhibit eutectic melting behavior, displaying a decrease in copolymer melting temperature and enthalpy up to the eutectic point of 30 wt-% PA-6,T, and a corresponding increase in both up to 60 wt-% PA-6T. Optically clear materials were obtained at 30 wt-% PA-6,T. Data collection was stopped at 60 wt-% due to phase separation of PA-6,T rich phases. Wide angle x-ray diffraction data displayed three distinct regions: 1) sharp PA-10,T crystal diffractions from 0-20% PA-6,T, 2) broad amorphous scattering between 25-45% PA-6,T, 3) sharp diffraction peaks from 50-60 wt% PA-6,T. All copolymers had relatively high glass transition temperatures from 137-149 °C determined from dynamic mechanical analysis. This study provides a method in which crystallinity and optical clarity of semi-aromatic polyamides can be tuned while maintaining high glass transition temperatures. In Chapter III, a novel, one pot polyamide-polyamide block copolymer synthetic strategy is explained. The synthesis of PA-12,T - PA-6 block copolymers occurs in two sequential steps, in which it was found that CaCl2 is needed to avoid crosslinking of the material. First, reaction variables of the solution, step growth polymerization of 1,12- diaminododecane and biscaprolactam terephthalamide (BCT) in caprolactam were investigated. PA-12,T with an average degree of polymerization of 15 and nterephthaloyl end groups was obtained using 5 mol-% excess BCT. The second stage of synthesis uses anionic polymerization of the caprolactam using the n-terephthaloyl capro lactam end groups. While CaC^ concentration had little effect on this step growth reaction, it was found that the CaCl2 greatly effected the conversion and transamidation of the anionic polymerization. This effect yielded a variety of materials with different molecular weights and blockiness that display unique thermal and solubility properties not obtained with polymer blends. Furthermore, this technique can be applied to wide variety of monomers to create novel polyamide-polyamide block copolymers currently undiscovered

Pseudo-contractions as Gentle Repairs

Updating a knowledge base to remove an unwanted consequence is a challenging task. Some of the original sentences must be either deleted or weakened in such a way that the sentence to be removed is no longer entailed by the resulting set. On the other hand, it is desirable that the existing knowledge be preserved as much as possible, minimising the loss of information. Several approaches to this problem can be found in the literature. In particular, when the knowledge is represented by an ontology, two different families of frameworks have been developed in the literature in the past decades with numerous ideas in common but with little interaction between the communities: applications of AGM-like Belief Change and justification-based Ontology Repair. In this paper, we investigate the relationship between pseudo-contraction operations and gentle repairs. Both aim to avoid the complete deletion of sentences when replacing them with weaker versions is enough to prevent the entailment of the unwanted formula. We show the correspondence between concepts on both sides and investigate under which conditions they are equivalent. Furthermore, we propose a unified notation for the two approaches, which might contribute to the integration of the two areas

Recombinant gelatin and collagen from methylotrophic yeasts

Based on its structural role and compatibility within the human body, collagen is a commonly used biomaterial in medical applications, such as cosmetic surgery, wound treatment and tissue engineering. Gelatin is in essence denatured and partly degraded collagen and is, as a result of its unique functional and chemical properties, also used in many medical and pharmaceutical products. Collagen and gelatin are traditionally extracted from animal tissues. The quality and the characteristics of the proteins are not very reproducible in today's batch-to-batch production processes and recently, potential contamination of collagen and gelatin with viruses and prions (causing BSE) became a matter of concern. BSE is thought to cause a new variety of the brain- wasting Creutzfeldt-Jacob disease in humans.Recombinant DNA technology may provide safe collagen and gelatins from which the quality and characteristics can precisely be controlled and reproduced and, in addition, opens up possibilities for novel functional "tailor-made" proteins.For the heterologous production of animal proteins yeasts are frequently used. Since yeasts are eukaryotes, most translational modification, needed for functionality and stability of recombinant animal proteins, normally occur. However prolyl 4-hydroxylation, essential for gelling properties of recombinant gelatin and thermal stability of recombinant collagen, is generally considered to be absent in yeast systems.In this study we explored the methylotrophic yeasts Hansenula polymorpha and Pichia pastoris for their use as recombinant production systems of natural and "tailor-made" gelatins and human collagen.We found that both yeasts are well able to cope with the repetitive gene sequences encoding animal gelatin and human collagen and showed that P. pastoris can produce synthetic gelatins with highly hydrophilic properties at high levels. Furthermore, it was discovered that H. polymorpha unexpectedly produced endogenous collagen-like proteins with 4-hydroxyproline amino acid residues. This finding indicated that the yeast H. polymorpha , in contract to what was generally believed, must contain intrinsic proly 4-hydroxyalse activity. Indeed, expression of murine gelatin in H. polymorpha yielded a secreted and hydroxylated product. We also investigated if H. polymorpha could be used for the production of recombinant human collagen. Intract human collagen trimers were obtained but they were not stable at temperatures higher than 15 °C, indicating that hydroxylation in the product was poor.In the course of this study we found putative prolyl 4-hydroxylase genes in different eukaryotic microbial systems. In the future these genes may be used to further develop yeasts into cell factories for the production of animal gelatins and thermally stable human collagen

PAN AIR: A computer program for predicting subsonic or supersonic linear potential flows about arbitrary configurations using a higher order panel method. Volume 2: User's manual (version 3.0)

A comprehensive description of user problem definition for the PAN AIR (Panel Aerodynamics) system is given. PAN AIR solves the 3-D linear integral equations of subsonic and supersonic flow. Influence coefficient methods are used which employ source and doublet panels as boundary surfaces. Both analysis and design boundary conditions can be used. This User's Manual describes the information needed to use the PAN AIR system. The structure and organization of PAN AIR are described, including the job control and module execution control languages for execution of the program system. The engineering input data are described, including the mathematical and physical modeling requirements. Version 3.0 strictly applies only to PAN AIR version 3.0. The major revisions include: (1) inputs and guidelines for the new FDP module (which calculates streamlines and offbody points); (2) nine new class 1 and class 2 boundary conditions to cover commonly used modeling practices, in particular the vorticity matching Kutta condition; (3) use of the CRAY solid state Storage Device (SSD); and (4) incorporation of errata and typo's together with additional explanation and guidelines