Model fit after pairwise maximum likelihood

Maximum likelihood factor analysis of discrete data within the structural equation modeling framework rests on the assumption that the observed discrete responses are manifestations of underlying continuous scores that are normally distributed. As maximizing the likelihood of multivariate response patterns is computationally very intensive, the sum of the log--likelihoods of the bivariate response patterns is maximized instead. Little is yet known about how to assess model fit when the analysis is based on such a pairwise maximum likelihood (PML) of two--way contingency tables. We propose new fit criteria for the PML method and conduct a simulation study to evaluate their performance in model selection. With large sample sizes (500 or more), PML performs as well the robust weighted least squares analysis of polychoric correlations

Prevalence of Defecation Disorders and their Symptoms is Comparable in Children and Young Adults:Cross-Sectional Study

Purpose: We aimed to compare the prevalence rates and associated symptoms of constipation and fecal incontinence in children and young adults and evaluate how these patient groups cope with these disorders. Methods: A cross-sectional study was performed in which 212 children (8-17 years) and 149 young adults (18-29 years) from the general Dutch population completed a questionnaire about defecation disorders. Results: Constipation occurred in 15.6% of children and 22.8% of young adults (p=0.55), while the prevalence of fecal incontinence was comparable between groups (7%, p=0.91). The symptoms associated with constipation occurred as often in children as in young adults, while most fecal incontinence symptoms occurred more often in young adults. Approximately 43% of children had constipation for more than 5 years, while 26% of young adults experienced constipation since childhood. Only 27% of constipated children and 21% of constipated young adults received treatment (mostly laxatives). For fecal incontinence, 13% of children and 36% of young adults received treatment (mostly antidiarrheal medications or incontinence pads). Conclusion: In contrast to the general belief, the prevalence of defecation disorders and associated symptoms seem to be comparable in children and young adults. Only a few people with defecation disorders receive adequate treatment

In vitro integration of ribosomal RNA synthesis, ribosome assembly, and translation

Purely in vitro ribosome synthesis could provide a critical step towards unraveling the systems biology of ribosome biogenesis, constructing minimal cells from defined components, and engineering ribosomes with new functions. Here, as an initial step towards this goal, we report a method for constructing Escherichia coli ribosomes in crude S150 E. coli extracts. While conventional methods for E. coli ribosome reconstitution are non-physiological, our approach attempts to mimic chemical conditions in the cytoplasm, thus permitting several biological processes to occur simultaneously. Specifically, our integrated synthesis, assembly, and translation (iSAT) technology enables one-step co-activation of rRNA transcription, assembly of transcribed rRNA with native ribosomal proteins into functional ribosomes, and synthesis of active protein by these ribosomes in the same compartment. We show that iSAT makes possible the in vitro construction of modified ribosomes by introducing a 23S rRNA mutation that mediates resistance against clindamycin. We anticipate that iSAT will aid studies of ribosome assembly and open new avenues for making ribosomes with altered properties

Augustine State: The Information Technology Component of Going Online

Finding cases appropriate for teaching information technology courses is a persistent problem for instructors. This article is written as a teaching case and is intended for use by instructors in educating students about information technology. The case information is factual and deals with genuine information technology situations at a real-world educational institution. The case offers the opportunity to generate student discussion in the areas of corporate and IT governance, IT infrastructure, IT architecture, open source software, outsourcing and other topics

Pilot-Scale Testing of In Situ Vitrification of Arnold Engineering Development Center Site 10 Contaminated Soils

Process verification testing using in situ vitrification (ISV) was successfully performed in a pilot-scale test using soils containing fuel oils and heavy metals from Site 10 Installation Restoration Program (IRP) at the Arnold Engineering Development Center (AEDC) located in the southern portion of middle Tennessee. This effort was directed through the U.S. Department of Energy ' s Hazardous Waste Remedial Action Program (HAZWRAP) Office managed by Martin Marietta Energy Systems. In situ vitrification is a thermal treatment process that converts contaminated soils and wastes into a durable product containing glass and crystalline phases. During processing, heavy metals or other inorganic constituents are retained and immobilized in the glass structure; organic constituents are typically destroyed or removed and captured by the off-gas treatment system. The objective of this test is to verify the applicability of the ISV process for stabilization of the contaminated soil at Site 10 . The pilotscale ISV testing results, reported herein, indicate that the AEDC Site 10 Fire Training Area may be successfully processed by ISV. Site 10 is a fire training pit that is contaminated with fuel oils and heavy metals from fire training exercises. Actual site material was processed by ISV to verify its feasible application to those soils . Initial feasibility bench-scale testing and analyses of the soils determined that a lower-melting, electrically conductive fluxing additive (such as sodium carbonate) is required as an additive to the soil for ISV processing to work effecti vely. The actual Site 10 soils showed a larger degree of compositional variation than the soil used for the bench-scale test . This variation dictates that each vitrification setting should be analyzed to determine the composition as. a function of depth and location . This data will dictate the amount (if any) of fluxing add itives of sodium and calci um to bring the melt composition to the recommended quantity of 5 wt% sodium and 5 wt% calcium oxide. Each variable additive adjustment would result in a vitrification melt composition of 5 wt% calcium and sodium oxide content . The pilot -scale operation created a vitrified block weighing 15 metric t onnes (t) and measuring 1.5 m (5 ft) deep and 2.4 m (8 ft) on each side. The quantity of fluxing additives and the method of placing the fluxing additives in the surface cover soil limited the operating electrical system providing power to the ISV melt. The power limitation created enhanced lateral growth of the block and resulted in a shallower depth . This method of adding fluxes demonstrated that ISV operating efficiency would be greatly improved if the fluxes were injected or mixed with the entire designated vitrification volume. However, the volume vitrified contained a sufficient quantity of hazardous contaminants to allow for an effective verification evaluation of ISV processing of the AEDC Site 10. Analytical efforts for this project were directed towards evaluating the organic destruction and thermal transport effects of ISV processing on the Site 10 contaminated soil. No thermal transport of hydrocarbon contaminants to the surrounding soil were detected. These results continue to confirm the organic destruction and nontransport mechanisms presented in this report . Off-gas releases of the hydrocarbons indicated an 89 wt% destruction efficiency by the ISV process exclusive of off-gas treatment. The destruction and removal efficiency of the overall ISV system was 99.85 wt%. Leach testing using extraction procedure (EP) toxicity and toxic characteristics leach procedure (TCLP) showed that all metals of concern were below leach testing release limits, indicating that the ISV process produces a nonhazardous product . These favorable results indicate that ISV can be used to effectively treat and remediate the contaminated soils at the AEDC Site 10

The Dutch Symptom Checklist-90-Revised:Is the Use of the Subscales Justified?

The Symptom Checklist-90-Revised (SCL-90-R; Derogatis, 1977, 1994) was constructed to measure both general psychological distress and specific primary symptoms of distress. In this study, we evaluated to what extent the scale scores of the Dutch SCL-90-R reflect general and/or specific aspects of psychological distress in a psychiatric outpatients sample (N = 1,842), using a hierarchical factor model. The results revealed that the total scale score measures general psychological distress, with high reliability. The subscale scores Sleep Difficulties, Agoraphobia, Hostility, and Somatization reflect the specific primary symptoms reasonably well, with high reliability. The subscale score Depression hardly measures specific symptoms of distress, but instead a very common construct as is measured with the total scale of the SCL-90-R. The use of the Depression subscale score beyond the total scale score of the SCL-90-R appears therefore of limited value in clinical practice

Differences in access and patient outcomes across antiretroviral treatment clinics in the Free State province: A prospective cohort study

Objective. To assess differences in access to antiretroviral treatment (ART) and patient outcomes across public sector treatment facilities in the Free State province, South Africa. Design. Prospective cohort study with retrospective database linkage. We analysed data on patients enrolled in the treatment programme across 36 facilities between May 2004 and December 2007, and assessed percentage initiating ART and percentage dead at 1 year after enrolment. Multivariable logistic regression was used to estimate associations of facility-level and patient-level characteristics with both mortality and treatment status. Results. Of 44 866 patients enrolled, 15 219 initiated treatment within 1 year; 8 778 died within 1 year, 7 286 before accessing ART. Outcomes at 1 year varied greatly across facilities and more variability was explained by facility-level factors than by patient-level factors. The odds of starting treatment within 1 year improved over calendar time. Patients enrolled in facilities with treatment initiation available on site had higher odds of starting treatment and lower odds of death at 1 year compared with those enrolled in facilities that did not offer treatment initiation. Patients were less likely to start treatment if they were male, severely immunosuppressed (CD4 count ≤50 cells/μl), or underweight

Biology by Design: From Top to Bottom and Back

Synthetic biology is a nascent technical discipline that seeks to enable the design and construction of novel biological systems to meet pressing societal needs. However, engineering biology still requires much trial and error because we lack effective approaches for connecting basic “parts” into higher-order networks that behave as predicted. Developing strategies for improving the performance and sophistication of our designs is informed by two overarching perspectives: “bottom-up” and “top-down” considerations. Using this framework, we describe a conceptual model for developing novel biological systems that function and interact with existing biological components in a predictable fashion. We discuss this model in the context of three topical areas: biochemical transformations, cellular devices and therapeutics, and approaches that expand the chemistry of life. Ten years after the construction of synthetic biology's first devices, the drive to look beyond what does exist to what can exist is ushering in an era of biology by design