Identifying profiles of youth characteristics, trajectories of development, and retention factors in a Positive Youth Development program

2017 Summer.Includes bibliographical references.Positive Youth Development (PYD) programs are an increasingly common form of intervention for youth of all backgrounds. In particular, PYD programs that take youth "off the streets" while not in school, termed out-of-school time (OST) programs, are of special interest to practitioners and researchers alike due to the diversity of programming available and the ecological contexts they provide. In addition, most youth engage in some form of risky behavior over the course of development, or are exposed to risk factors out of their control. However, PYD programs as a whole have provided little evidence of having meaningful impacts on the youth they serve, and they continually struggle to serve youth from disadvantaged backgrounds or who engage in risky behaviors. These shortcomings potentially result from selection bias that manifests through high attrition rates, which are influenced by many factors, such as a lack of programs to choose from or disinterest in program content. Even when attrition is partially accounted for, evaluating program impacts is difficult, as the processes and outcomes that define PYD remain relatively unclear, including their relation to risk factors. Therefore, in order for PYD programs, and specifically those categorized as OST, to take the next step in increasing and demonstrating the impacts of their programs, additional collaboration and research in a real world context is needed. This dissertation will use data from a PYD program, SOS University, to address two primary research questions. The first study will address the question of, are there specific factors that are associated with youth attrition from PYD programs? This research is timely as prevention scientists have struggled to provide guidance to practitioners on how to minimize attrition rates, a commonly cited impediment to translating scholarly research into real world application. The second study seeks to answer the question, can youth be distinguished into profiles of development characterized by the patterns of responses to PYD indicators? To answer this question, the second study will analyze differences in youth development profiles as they participated in an outdoor leadership program over the course of three years. This study is important in that it has the potential to highlight the positive development that can occur in the context of experiencing or engaging in risk behaviors. The dissertation is organized as follows. Chapter I provides an overview of the existing literature on theory related to PYD and the evidence base for PYD and OST programs. Chapters II and III are studies I and II cited above, respectively. Chapters II and II follow the typical format of an academic manuscript. That is, each chapter will include a more refined literature review that provides an in-depth view of research related to the study at hand, a description of the current study, methods, data analysis approaches and results, and then a discussion. Finally, Chapter IV will be a general discussion of the overall results and how they relate to one another. Additionally, Chapter IV will review overarching strengths and weaknesses of the dissertation, and finally highlight implications that may surface as a result of the studies, including a discourse on future steps that can be taken to increase collaboration between the scientific and applied communities

Hepatitis C virus cell-cell transmission and resistance to direct-acting antiviral agents

Hepatitis C virus (HCV) is transmitted between hepatocytes via classical cell entry but also uses direct cell-cell transfer to infect neighboring hepatocytes. Viral cell-cell transmission has been shown to play an important role in viral persistence allowing evasion from neutralizing antibodies. In contrast, the role of HCV cell-cell transmission for antiviral resistance is unknown. Aiming to address this question we investigated the phenotype of HCV strains exhibiting resistance to direct-acting antivirals (DAAs) in state-of-the-art model systems for cell-cell transmission and spread. Using HCV genotype 2 as a model virus, we show that cell-cell transmission is the main route of viral spread of DAA-resistant HCV. Cell-cell transmission of DAA-resistant viruses results in viral persistence and thus hampers viral eradication. We also show that blocking cell-cell transmission using host-targeting entry inhibitors (HTEIs) was highly effective in inhibiting viral dissemination of resistant genotype 2 viruses. Combining HTEIs with DAAs prevented antiviral resistance and led to rapid elimination of the virus in cell culture model. In conclusion, our work provides evidence that cell-cell transmission plays an important role in dissemination and maintenance of resistant variants in cell culture models. Blocking virus cell-cell transmission prevents emergence of drug resistance in persistent viral infection including resistance to HCV DAAs

Energy and environmental research emphasizing low-rank coal: Task 3.9 catalytic tar cracking

Tar produced in the gasification of coal is deleterious to the operation of downstream equipment, including fuel cells, gas turbines, hot-gas stream cleanup filters, and pressure-swing absorption systems. Catalytic cracking of tars to smaller hydrocarbons can be an effective means of removing these tars from gas streams and, in the process, generating useful products, such as methane gas, which is crucial to operation of molten carbonate fuel cells. Aerosol tars are not readily removed from gas streams by conventional means and, as a consequence, often end up plugging filters or fouling fuel cells, turbines, or sorbents. Catalytic cracking of these tars to molecular moieties of C{sub 10} or smaller would prevent the problems commonly attributed to the tars. As an example, the moving Bourdon fixed-bed gasifier, by virtue of its efficient countercurrent heat exchange and widespread commercial use, may offer the lowest-cost integrated gasification combined-cycle (IGCC) system if tar generation and wastewater contamination can be minimized. We evaluate the potential of selected catalysts to minimize tar accumulation and maximize char conversion to useful liquid and/or gaseous products. Owing to the potential for production of extremely toxic nickel carbonyl gas, care must be exercised in the use of a NISMM catalyst for cracking tars at high temperatures in reducing atmospheres such as those produced by coal gasification. We observed a fifty percent or more of tar produced during steam gasification of Beulah lignite at temperatures of 400{degrees}-800+{degrees}C when cracked by either dolomite or zeolite maintained at a temperature of 50{degrees}C-100{degrees}C below that of the reactor

Energy and environmental research emphasizing low-rank coal--Task 4.4: Development of supercritical fluid extraction methods for the quantitation of sulfur forms in coal

Current analytical methods are inadequate for accurately measuring sulfur forms in coal. This task was concerned with developing methods to quantitate and identify major sulfur forms in coal based on direct measurement (as opposed to present techniques based on indirect measurement and difference values). The focus was on the forms that were least understood and for which the analytical methods have been the poorest, i.e., organic and elemental sulfur. Improved measurement techniques for sulfatic and pyritic sulfur also need to be developed. A secondary goal was to understand the interconversion of sulfur forms in coal during thermal processing. This task had as its focus the development of selective extraction methods that will allow the direct measurement of sulfur content in each form. Therefore, selective extraction methods were needed for the major sulfur forms in coal, including elemental, pyritic, sulfatic, and organic sulfur. This study was a continuation of that of previous analytical method development for sulfur forms in coal which resulted in the successful isolation and quantitation of elemental and sulfatic sulfur. Super- and subcritical extractions with methanol or water with and without additives were investigated in an attempt to develop methods for pyritic and organic sulfur forms analysis in coal. Based on these studies, a sequential extraction scheme that is capable of selectively determining elemental, sulfatic, pyritic and two forms of organic sulfur is presented here

Impact of Sugar Substitutes on Glucose Control in Diabetic Patients

Objective: To evaluate the impact of nonnutritive sugar substitutes on glycemic control in patients with diabetes. Data Sources: A comprehensive review of the literature was conducted in PubMed (1966-March 2012) and Scopus. A combination of MeSH terms and keywords were used, including acesulfame, aspartame, diabetes, neotame, rebiana, saccharin, stevia, and sucralose. Study Selection and Data Extraction: Clinical studies evaluating the impact of nonnutritive sweeteners on measures of diabetic control, including, but not limited to, blood glucose levels, postprandial blood glucose, and hemoglobin A1c were selected for review. Searches were limited to only nonnutritive sweeteners available in the US. Data Synthesis: Nine clinical trials that evaluated nonnutritive sweeteners in a total of 490 patients with diabetes were found. Doses of sweeteners in the studies varied from below acceptable daily intake levels for 3 consecutive days to daily dosing for up to 18 weeks and up to 3.5 times the acceptable daily intake levels. No significant differences in overall effects on glycemic control and insulin response were found. Conclusions: Nonnutritive sweeteners do not appear to affect glycemic control in patients with diabetes. Patients should be counseled to maintain an appropriate energy balance in their diet, with or without the use of nonnutritive sweeteners

Task 20 - Prevention of Chloride Corrosion in High-Temperature Waste Treatment Systems (Corrosives Removals from Vitrification Slurries)

GTS Duratek is working with BNFL Incorporated on a US Department of Energy (DOE) contract to develop a facility to treat and immobilize radioactive waste at the Hanford site in southeast Washington. Development of the 10-ton/day Hanford facility will be based on findings from work at Duratek's 3.3-ton/day pilot plant in Columbia, Maryland, which is in the final stage of construction and scheduled for shakedown testing in early 1999. In prior work with the Catholic University of America Vitreous State Laboratory, Duratek has found that slurrying is the most efficient way to introduce low-level radioactive, hazardous, and mixed wastes into vitrification melters. However, many of the Hanford tank wastes to be vitrified contain species (primarily chloride and sulfate) that are corrosive to the vitrifier or the downstream air pollution control equipment, especially under the elevated temperature conditions existent in these components. Removal of these corrosives presents a significant challenge because most tank wastes contain high (up to 10-molar) concentrations of sodium hydroxide (NaOH) along with significant levels of nitrate, nitrite, and other anions, which render standard ion-exchange, membrane filtration, and other separation technologies relatively ineffective. In Task 20, the Energy and Environmental Research Center (EERC) will work with Duratek to develop and optimize a vitrification pretreatment process for consistent, quantitative removal of chloride and sulfate prior to vitrifier injection

Oral drug delivery strategies for development of poorly water soluble drugs in paediatric patient population

Selecting the appropriate formulation and solubility-enabling technology for poorly water soluble drugs is an essential element in the development of formulations for paediatric patients. Different methodologies and structured strategies are available to select a suitable approach and guide formulation scientists for development of adult formulations. However, there is paucity of available literature for selection of technology and overcoming the challenges in paediatric formulation development. The need for flexible dosing, and the limited knowledge of the safety of many formulation excipients in paediatric subjects, impose significant constraints and in some instances require adaptation of the approaches taken to formulating these drugs for the adult population. Selection of the best drug delivery system for paediatrics requires an efficient, systematic approach that considers a drug's physical and chemical properties and the targeted patient population's requirements. This review is a step towards development of a strategy for the design of solubility enhancing paediatric formulations of highly insoluble drugs. The aim of this review is to provide an overview of different approaches and strategies to consider in order to assist development of paediatric formulation for poorly water-soluble drugs with the provision of examples of some marketed products. In addition, it provides recommendations to overcome the range of challenges posed by these strategies and adaptations of the adult approach/product presentation required to enable paediatric drug development and administration

Oxygen supply capacity breathes new life into critical oxygen partial pressure (Pcrit)

Author Posting. © Company of Biologists, 2021. This article is posted here by permission of Company of Biologists for personal use, not for redistribution. The definitive version was published in Journal of Experimental Biology 224(8), (2021): jeb242210, https://doi.org/10.1242/jeb.242210.The critical oxygen partial pressure (Pcrit), typically defined as the PO2 below which an animal's metabolic rate (MR) is unsustainable, is widely interpreted as a measure of hypoxia tolerance. Here, Pcrit is defined as the PO2 at which physiological oxygen supply (α0) reaches its maximum capacity (α; µmol O2 g−1 h−1 kPa−1). α is a species- and temperature-specific constant describing the oxygen dependency of the maximum metabolic rate (MMR=PO2×α) or, equivalently, the MR dependence of Pcrit (Pcrit=MR/α). We describe the α-method, in which the MR is monitored as oxygen declines and, for each measurement period, is divided by the corresponding PO2 to provide the concurrent oxygen supply (α0=MR/PO2). The highest α0 value (or, more conservatively, the mean of the three highest values) is designated as α. The same value of α is reached at Pcrit for any MR regardless of previous or subsequent metabolic activity. The MR need not be constant (regulated), standardized or exhibit a clear breakpoint at Pcrit for accurate determination of α. The α-method has several advantages over Pcrit determination and non-linear analyses, including: (1) less ambiguity and greater accuracy, (2) fewer constraints in respirometry methodology and analysis, and (3) greater predictive power and ecological and physiological insight. Across the species evaluated here, α values are correlated with MR, but not Pcrit. Rather than an index of hypoxia tolerance, Pcrit is a reflection of α, which evolves to support maximum energy demands and aerobic scope at the prevailing temperature and oxygen level.This project was supported by National Oceanic and Atmospheric Administration grants NA18NOS4780167 and NA17OAR4310081 and National Science Foundation grant OCE-1459243 to B.A.S., the Jack and Katharine Ann Lake Fellowship to A.A., the Anne and Werner Von Rosenstiel Fellowship and Garrels Memorial Endowed Fellowship to A.W.T., the Hogarth Fellowship to C.J.W., the Southern Kingfish Association Fellowship to A.L.B., and a National Science Foundation postdoctoral fellowship (DBI-1907197) to M.A.B.2022-04-3

A Facile Approach to Alumina-Supported Pt Catalysts for the Dehydrogenation of Propane

The catalytic dehydrogenation of propane is an economically interesting process for the production of propylene due to its high selectivity to the olefin and the coupled generation of hydrogen. The catalysts are usually obtained by depositing the active components from solutions onto a support. Here we show that the direct synthesis of alumina-supported platinum catalysts in a ball mill in a single step provides easy access to efficient catalysts that are comparable in performance to materials obtained by more complex synthesis techniques. This was demonstrated by analysis using XRD, N2 adsorption, chemical analysis, FTIR spectroscopy, and electron microscopy and by functional characterization of the catalysts in the dehydrogenation of propane to propylene. Although the ball milling procedure was not optimized, the catalysts exhibit a narrow Pt particle size distribution around 2 nm and are active at comparatively low reaction temperatures, producing in the steady state at 500 °C approximately 300 gpropylene gPt-1 h-1. The selectivity remains very high even at temperatures as high as 550 °C. Sintering of Pt under the harsh reaction conditions is not observed. The scalable method saves energy and avoids waste as no solvents and no thermal or reducing pretreatments are required