33 research outputs found
Humanities-based Curriculum Online: A Role for the Arts in Designing Web-Based Interdisciplinary Inquiry
The ability of ArtsOnline, a web site designed by professionals at the Los Angeles Educational Partnership (LAEP), to support interdisciplinary inquiry for an arts-centered, humanities-based, program at the Los Angeles Unified School District (LAUSD), was evaluated from June to August in 1999. As research findings reported herein show, design barriers and challenges can lessen the benefits from application of IT for interdisciplinary inquiry. Some of the design barriers and challenges mentioned included inadequate web site design, insufficient editing and information presentation, along with low access to IT by teachers and students, lack of funding, low administrative support and lack of teacher training. Findings detailed in this paper are from transcripts developed from five focus groups (N=30) convened at UCLA to evaluate ArtsOnline. The UCLA Armand Hammer Museum and Grunwald Center for the Graphics Arts and LAEP funded the evaluation
Is HIV Infection a Risk Factor for Multi-Drug Resistant Tuberculosis? A Systematic Review
BACKGROUND:Tuberculosis (TB) is an important cause of human suffering and death. Human immunodeficiency virus (HIV), multi-drug resistant TB (MDR-TB), and extensive drug resistant tuberculosis (XDR-TB) have emerged as threats to TB control. The association between MDR-TB and HIV infection has not yet been fully investigated. We conducted a systematic review and meta-analysis to summarize the evidence on the association between HIV infection and MDR-TB. METHODS AND RESULTS:Original studies providing Mycobacterium tuberculosis resistance data stratified by HIV status were identified using MEDLINE and ISI Web of Science. Crude MDR-TB prevalence ratios were calculated and analyzed by type of TB (primary or acquired), region and study period. Heterogeneity across studies was assessed, and pooled prevalence ratios were generated if appropriate. No clear association was found between MDR-TB and HIV infection across time and geographic locations. MDR-TB prevalence ratios in the 32 eligible studies, comparing MDR-TB prevalence by HIV status, ranged from 0.21 to 41.45. Assessment by geographical region or study period did not reveal noticeable patterns. The summary prevalence ratios for acquired and primary MDR-TB were 1.17 (95% CI 0.86, 1.6) and 2.72 (95% CI 2.03, 3.66), respectively. Studies eligible for review were few considering the size of the epidemics. Most studies were not adjusted for confounders and the heterogeneity across studies precluded the calculation of a meaningful overall summary measure. CONCLUSIONS:We could not demonstrate an overall association between MDR-TB and HIV or acquired MDR-TB and HIV, but our results suggest that HIV infection is associated with primary MDR-TB. Future well-designed studies and surveillance in all regions of the world are needed to better clarify the relationship between HIV infection and MDR-TB
Unbiased Bayesian inference for population Markov jump processes via random truncations
We consider continuous time Markovian processes where populations of
individual agents interact stochastically according to kinetic rules. Despite
the increasing prominence of such models in fields ranging from biology to
smart cities, Bayesian inference for such systems remains challenging, as these
are continuous time, discrete state systems with potentially infinite
state-space. Here we propose a novel efficient algorithm for joint state /
parameter posterior sampling in population Markov Jump processes. We introduce
a class of pseudo-marginal sampling algorithms based on a random truncation
method which enables a principled treatment of infinite state spaces. Extensive
evaluation on a number of benchmark models shows that this approach achieves
considerable savings compared to state of the art methods, retaining accuracy
and fast convergence. We also present results on a synthetic biology data set
showing the potential for practical usefulness of our work
Phase Balancing and Reactive Power Support Services for Microgrids
Alternating current (AC) microgrids are expected to operate as active components within smart distribution grids in the near future. The high penetration of intermittent renewable energy sources and the rapid electrification of the thermal and transportation sectors pose serious challenges that must be addressed by modern distribution system operators. Hence, new solutions should be developed to overcome these issues. Microgrids can be considered as a great candidate for the provision of ancillary services since they are more flexible to coordinate their distributed generation sources and their loads. This paper proposes a method for compensating microgrid power factor and loads asymmetries by utilizing advanced functionalities enabled by grid tied inverters of photovoltaics and energy storage systems. Further, a central controller has been developed for adaptively regulating the provision of both reactive power and phase balancing services according to the measured loading conditions at the microgrid’s point of common coupling. An experimental validation with a laboratory scale inverter and a real time hardware in the loop investigation demonstrates that the provision of such ancillary services by the microgrid can significantly improve the operation of distribution grids in terms of power quality, energy losses and utilization of available capacity
Optimization of a Colorimetric Assay to Determine Lactate Dehydrogenase B Activity Using Design of Experiments
Finding fathers : spatio-temporal analysis of paternity assignment in grey seals (Halichoerus grypus).
Molecular studies of pinniped breeding systems exhibit a broad range of agreement and disagreement with observational indices of male breeding success. Grey seal studies have reported considerable discrepancies between genetic and behavioural paternity measures that have been interpreted as evidence of previously unidentified male strategies and/or tactics. Therefore, these studies have the power to fundamentally alter our perceptions of mating systems. However, other pinniped studies exhibit no such disagreements, and one possible explanation for disparities may be sampling biases in space and time. Therefore, it is essential that potential sampling biases are examined to evaluate the likelihood of previously unidentified male strategies. We examined paternities assigned at the North Rona grey seal colony between 1999 and 2002 in relation to concurrent detailed behavioural and locational data for males and females. We found that (i) for females observed in sexual interaction(s) during their oestrus period, it was highly probable that one of the interacting males fathered their next pup; (ii) over 80% of assigned paternities agreed with observations of the in-colony behaviour and spatio-temporal proximity of the males and females involved; and (iii) a minority of females exhibit mate choice and seek sires outside their local male's home range, although evidence suggests that these females mate on the colony rather than at sea. In conclusion, nearly all paternities assigned agreed with expectation based upon detailed knowledge of the spatio-temporal patterns of individuals during the breeding season. We found little evidence of unidentified male strategies at North Rona, Scotland, whereas further examination of mechanisms of female choice may be productive