Spherical solid-propellant rocket motor Patent

Spherical solid propellant rocket engine desig

Silent No More: The Formation of Academic Self-Efficacy Among Black Male Community College Students

Alarming rates of Black male underachievement in the community college are compelling reasons to explore factors that promote their academic success. Black male community college students have the lowest grade point averages among males across all races and ethnicities, and the highest rates of attrition (Department of Education, 2008; Ross et al., 2012). Sadly, the educational experiences of Black males have been characterized by racial discrimination, negative portrayals, marginalization, and lowered expectations. As academic self-efficacy has been found to promote the academic achievement of collegians, this study investigated the factors which have the greatest influence on the academic self-efficacy beliefs among diverse community college students and Black male’s perceptions of these beliefs. A two-phase, sequential, explanatory mixed methods design was employed, beginning with a quantitative data collection and analysis, followed by a qualitative approach. One hundred and nine participants were sampled in Phase 1 on the investigation, with descriptive statistics revealing little variance between the participants’ academic self-efficacy scores. Overall, Black students were found to have the highest levels of academic self-efficacy among all racial and ethnic groups. In addition, educational aspirations were found to be the strongest predictors of students’ academic self-efficacy. Purposive sampling was used to identify 17 Black male interview participants for Phase 2 of the study, to explore their perceptions of the experiences that have influenced their academic self-efficacy beliefs. The qualitative analysis revealed that institutional and familial support contributed to the formation of academic self-efficacy beliefs. Moreover, encounters with bullying and school violence were found to negatively impact the educational experiences of Black male participants

Optimal control of the propagation of a graph in inhomogeneous media

We study an optimal control problem for viscosity solutions of a Hamilton–Jacobi equation describing the propagation of a one-dimensional graph with the control being the speed function. The existence of an optimal control is proved together with an approximate controllability result in the $H^{-1}$-norm. We prove convergence of a discrete optimal control problem based on a monotone finite difference scheme and describe some numerical results

Incidence of lung tumours induced by urethane in mice exposed to reduced atmospheric pressure.

INBRED mice of strain A are well known to possess a high incidence of pulmonary adenomas whether spontaneous or induced, whereas strain C57B1 mice show a very low incidence, which according to Bloom and Falconer (1964) is genetically determined. In attempting to overcome this natural resistance of C57B1 mice to tumour development several observations led us to vary the oxygen tension in which mice were maintained. Heston and Pratt (1956, 1959) employed high or low oxygen tensions in a chamber for two days and found respectively increased or diminished incidences of dibenzanthracene-induced lung tumours in strain A mice. On the other hand, Mori-Chavez (1962b) observed an increase in the number and in the size of urethane-induced tumours in strain A mice maintained at a natural high altitude for eight or more months, and Heppleston and Simnett (1964) found that elevated oxygen tension produced deleterious effects on lung tissue and pulmonary adenomas from high incidence strains maintained in organ culture. Strains of mice susceptible and resistant to tumour induction by urethane were therefore exposed for prolonged periods to low atmospheric pressur

Incentives facing UK-listed companies to comply with the risk reporting provisions of the UK Corporate Governance Code

Recent changes made to the UK Corporate Governance Code require UK firms to report new or enhanced narrative information concerning their principal risks, their risk management processes and their future viability. This paper analyses whether the level and nature of voluntary compliance with these new requirements is consistent with alternative economic and political visibility incentives. We analyse relevant sections of financial reports produced by industry matched samples of large-, mid-and small-cap UK listed firms during the transitional 2013-14 financial reporting years. Both specific and generic readability attributes of the reports are measured. We find that virtually no firm in our sample has provided any viability statement. Empirical analysis of disclosures concerning principal risk assessment and review processes appear to be primarily motivated by political visibility reasons. Examples of particularly good and cases of poor corporate risk reporting practices are also discussed. Possible implications for the actuarial profession are discussed

Improving the economic value of photographic screening for optical coherence tomography-detectable macular oedema : a prospective, multicentre, UK study

Peer reviewedPublisher PD

ACADEMIC DISCIPLINE «ALTERNATIVE ENERGY»: A TUTORIAL ASPECT

The necessity to update academic discipline contents taking into account international experience is shown. At the School of Ecology in the framework of British Council project «Alternative Energy: Education and Science» (implemented together with Keele University, UK) the course «Alternative Energy» was updated: new topics were included, new methods of teaching were introduced. The content of the course is presented in details. Due to up-dating students receive new competencies which allow them to solve complex problems and to be more competitive on the labour market

Derivation and solution of effective-medium equations for bulk heterojunction organic solar cells

A drift-diffusion model for charge transport in an organic bulk-heterojunction solar cell, formed by conjoined acceptor and donor materials sandwiched between two electrodes, is formulated. The model accounts for (i) bulk photogeneration of excitons, (ii) exciton drift and recombination, (iii) exciton dissociation (into polarons) on the acceptor-donor interface, (iv) polaron recombination, (v) polaron dissociation into a free electron (in the acceptor) and a hole (in the donor), (vi) electron/hole transport and (vii) electron-hole recombination on the acceptor-donor interface. A finite element method is employed to solve the model in a cell with a highly convoluted acceptor/donor interface. The solutions show that, with physically realistic parameters, and in the power generating regime, the solution varies little on the scale of the microstructure. This motivates us to homogenise over the microstructure; a process that yields a far simpler one-dimensional effective medium model on the cell scale. The comparison between the solution of the full model and the effective medium (homogenised) model is very favourable for the applied voltages that are less than the built-in voltage (the power generating regime) but breaks down as the applied voltages increases above it. Furthermore, it is noted that the homogenisation technique provides a systematic way to relate effective medium modelling of bulk heterojunctions [19, 25, 36, 37, 42, 59] to a more fundamental approach that explicitly models the full microstructure [8, 38, 39, 58] and that it allows the parameters in the effective medium model to be derived in terms of the geometry of the microstructure. Finally, the effective medium model is used to investigate the effects of modifying the microstructure geometry, of a device with an interdigitated acceptor/donor interface, on its current-voltage curve

Investigating bacteriophages targeting the opportunistic pathogen Acinetobacter baumannii

The multi-drug resistance of the opportunistic pathogen Acinetobacter baumannii is of growing concern, with many clinical isolates proving to be resistant to last resort as well as front line antibiotic treatments. The use of bacteriophages is an attractive alternative to controlling and treating this emerging nosocomial pathogen. In this study, we have investigated bacteriophages collected from hospital wastewater in Thailand and we have explored their activity against clinical isolates of A. baumannii. Bacteriophage vB_AbaM_PhT2 showed 28% host range against 150 multidrug resistant (MDR) isolates and whole genome sequencing did not detect any known virulence factors or antibiotic resistance genes. Purified vB_AbaM_PhT2 samples had endotoxin levels below those recommended for preclinical trials and were not shown to be directly cytotoxic to human cell lines in vitro. The treatment of human brain and bladder cell lines grown in the presence of A. baumannii with this bacteriophage released significantly less lactate dehydrogenase compared to samples with no bacteriophage treatment, indicating that vB_AbaM_PhT2 can protect from A. baumannii induced cellular damage. Our results have also indicated that there is synergy between this bacteriophage and the end line antibiotic colistin. We therefore propose bacteriophage vB_AbaM_PhT2 as a good candidate for future research and for its potential development into a surface antimicrobial for use in hospitals. View Full-Tex