An initial evaluation of gellan gum as a material for tissue engineering applications

Alpha-modified minimum essential medium (αMEM) has been found to cross-link a 1% gellan gum solution, resulting in the formation of a self-supporting hydrogel in 1:1 and 5:1 ratios of polysaccharide: αMEM. Rheological data from temperature sweeps confirm that in addition to orders of magnitude differences in G' between 1% gellan and 1% gellan with αMEM, there is also a 20°C increase in the temperature at which the onset of gelation takes place when αMEM is present. Frequency sweeps confirm the formation of a true gel; mechanical spectra for mixtures of gellan and αMEM clearly demonstrate G' to be independent of frequency. It is possible to immobilize cells within a three-dimensional (3D) gellan matrix that remain viable for up to 21 days in culture by adding a suspension of rat bone marrow cells (rBMC) in αMEM to 1% gellan solution. This extremely simple approach to cell immobilization within 3D constructs, made possible by the fact that gellan solutions cross-link in the presence of millimolar concentrations of cations, poses a very low risk to a cell population immobilized within a gellan matrix and thus indicates the potential of gellan for use as a tissue engineering scaffold. © 2007 Sage Publications.

The Initial Stage of Teaching Proof in Mathematics Course

This article discusses techniques for organization of propaedeutic stage of teaching proof in mathematics course. It identifies types of tasks that allow students of 5–6 classes to form the ability to carry out simple proofs. This article describes each type of tasks features, it gives some examples.

Tracing the evolution of physics on the backbone of citation networks

Many innovations are inspired by past ideas in a nontrivial way. Tracing these origins and identifying scientific branches is crucial for research inspirations. In this paper, we use citation relations to identify the descendant chart, i.e., the family tree of research papers. Unlike other spanning trees that focus on cost or distance minimization, we make use of the nature of citations and identify the most important parent for each publication, leading to a treelike backbone of the citation network. Measures are introduced to validate the backbone as the descendant chart. We show that citation backbones can well characterize the hierarchical and fractal structure of scientific development, and lead to an accurate classification of fields and subfields. © 2011 American Physical Society.

Development of physics-based models and design optimization of power electronic conversion systems

The main objective for physics based modeling of the power converter components is to design the whole converter with respect to physical and operational constraints. Therefore, all the elements and components of the energy conversion system are modeled numerically and combined together to achieve the whole system behavioral model. Previously proposed high frequency (HF) models of power converters are based on circuit models that are only related to the parasitic inner parameters of the power devices and the connections between the components. This dissertation aims to obtain appropriate physics-based models for power conversion systems, which not only can represent the steady state behavior of the components, but also can predict their high frequency characteristics. The developed physics-based model would represent the physical device with a high level of accuracy in predicting its operating condition. The proposed physics-based model enables us to accurately develop components such as; effective EMI filters, switching algorithms and circuit topologies [7]. One of the applications of the developed modeling technique is design of new sets of topologies for high-frequency, high efficiency converters for variable speed drives. The main advantage of the modeling method, presented in this dissertation, is the practical design of an inverter for high power applications with the ability to overcome the blocking voltage limitations of available power semiconductor devices. Another advantage is selection of the best matching topology with inherent reduction of switching losses which can be utilized to improve the overall efficiency. The physics-based modeling approach, in this dissertation, makes it possible to design any power electronic conversion system to meet electromagnetic standards and design constraints. This includes physical characteristics such as; decreasing the size and weight of the package, optimized interactions with the neighboring components and higher power density. In addition, the electromagnetic behaviors and signatures can be evaluated including the study of conducted and radiated EMI interactions in addition to the design of attenuation measures and enclosures.

On the Initial Stages of the Densification and Lithification of Sediments

Peer reviewed

On the Initial Stages of the Densification and Lithification of Sediments

Peer reviewed

Invaluable but Invisible: an Initial Investigation of Chinese Graduate Skill Development and Subsequent Skill Use

Measures of impact of Higher Education have often neglected the Chinese student view, despite the importance of these students to the UK and Chinese economy. This research paper details the findings of a quantitative survey that was purposively distributed to Chinese graduates who enrolled at the University of Worcester on the Business Management degree between 2004-2011 (n=49). Analysis has been conducted on their skill development throughout their degree, their skill usage in different employment contexts, the value of their degree, and gender differences in skill development and usage. Discrepancies between skill development and usage, between males and females, and with previous research findings are discussed. Future research directions are also specified.

Theoretical Performance Model and Initial Experimentation of a Baffled-Tube Ram Accelerator

Thesis (Master's)--University of Washington, 2016-08

Ischemic Stroke as the Initial Manifestation of Neurosyphilis in a Young Adult Patient Positive for Human Immunodeficiency Virus

A 31-year-old man with pontine infarction was referred to our hospital for further evaluation and treatment. At admission, his neurological examination was unremarkable. No lymphadenopathy or skin lesions were found. The Treponema pallidum haemagglutination test, rapid plasma regain test and fluorescent treponemal antibody absorption test of immunoglobulin G were positive in both serum and cerebrospinal fluid (CSF). CSF analysis showed lymphocytic pleocytosis. The patient had male-to-male sexual contact and was found to be HIV positive. Physicians should be aware that acute ischaemic stroke may be the first manifestation of neurosyphilis in a young adult, especially with HIV infection.

RACISM IN DIGITAL ERA: DEVELOPMENT AND INITIAL VALIDATION OF THE PERCEIVED ONLINE RACISM SCALE (PORS V1.0)

Racism continues to thrive on the Internet. Yet, little is known about racism in online settings and the potential consequences. The purpose of this study was to develop the Perceived Online Racism Scale (PORS), the first measure to assess people’s perceived online racism experiences as they interact with others and consume information on the Internet. Items were developed through a multi-stage process based on literature review, focus-groups, and qualitative data collection. Based on a racially diverse large-scale sample (N = 1023), exploratory and confirmatory factor analyses provided support for a 30-item bifactor model with the following three factors: (a) 14-item PORS-IP (personal experiences of racism in online interactions), (b) 5-item PORS-V (observations of other racial/ethnic minorities being offended), and (c) 11-item PORS-I (consumption of online contents and information denigrating racial/ethnic minorities and highlighting racial injustice in society). Initial construct validity examinations suggest that PORS is significantly linked to psychological distress.

The influence of the initial state of nutrition on the lifespan of patients with amyotrophic lateral sclerosis (ALS) during home enteral nutrition

Aim: Amyotrophic lateral sclerosis (ALS) is a chronic, neurodegenerative disease, which leads to development of malnutrition. The main purpose of this research was to analyze the impact of malnutrition on the course of the disease and long-term survival. Material and methods: A retrospective analysis has been performed on 48 patients (22 F [45,83%] and 26 M [54,17%], the average age of patients: 66,2 [43-83]) in 2008-2014.The analysis of the initial state of nutrition was measured by body mass index (BMI), nutritional status according to NRS 2002, SGA and concentration of albumin in blood serum. Patients were divided into two groups, depending on the state of nutrition: well-nourished and malnourished. The groups were created separately for each of these, which allowed an additional comparative analysis of techniques used for the assessment of nutritional status. Results: Proper state of nutrition was interrelated with longer survival (SGA: 456 vs. 679 days, NRS: 312 vs. 659 vs. 835 days, BMI: respectively, 411, 541, 631 days, results were statistically significant for NRS and BMI). Concentration of albumin was not a prognostic factor, but longer survival was observed when level of albumin was increased during nutritional therapy. Conclusions: The initial nutrition state and positive response to enteral feeding is associated with better survival among patients with ALS. For this reason, nutritional therapy should be introduced as soon as possible.

Development of Physics-based Models and Design Optimization of Power Electronic Conversion Systems

The main objective for physics based modeling of the power converter components is to design the whole converter with respect to physical and operational constraints. Therefore, all the elements and components of the energy conversion system are modeled numerically and combined together to achieve the whole system behavioral model. Previously proposed high frequency (HF) models of power converters are based on circuit models that are only related to the parasitic inner parameters of the power devices and the connections between the components. This dissertation aims to obtain appropriate physics-based models for power conversion systems, which not only can represent the steady state behavior of the components, but also can predict their high frequency characteristics. The developed physics-based model would represent the physical device with a high level of accuracy in predicting its operating condition. The proposed physics-based model enables us to accurately develop components such as; effective EMI filters, switching algorithms and circuit topologies [7]. One of the applications of the developed modeling technique is design of new sets of topologies for high-frequency, high efficiency converters for variable speed drives. The main advantage of the modeling method, presented in this dissertation, is the practical design of an inverter for high power applications with the ability to overcome the blocking voltage limitations of available power semiconductor devices. Another advantage is selection of the best matching topology with inherent reduction of switching losses which can be utilized to improve the overall efficiency. The physics-based modeling approach, in this dissertation, makes it possible to design any power electronic conversion system to meet electromagnetic standards and design constraints. This includes physical characteristics such as; decreasing the size and weight of the package, optimized interactions with the neighboring components and higher power density. In addition, the electromagnetic behaviors and signatures can be evaluated including the study of conducted and radiated EMI interactions in addition to the design of attenuation measures and enclosures.