Isomeric Carborane Neuromuscular Blocking Agents

We synthesized a family of neuromuscular blocking agents (NMB) based on decamethonium, but containing a carborane cluster in the methylene chain between the two quaternary ammonium groups. The carborane cluster isomers o-NMB, m-NMB, and p-NMB were tested in animals for neuromuscular block and compared with agents used clinically: rocuronium and decamethonium. All three isomers caused reversible muscle weakness in mice as determined by grip strength and inverted screen tests, with a potency rank of p-NMB > rocuronium > decamethonium > m-NMB > o-NMB. The mechanism of action of the compounds was determined by using the in vitro rat phrenic nerve hemi-diaphragm preparation and electrophysiologic measurements in cells. Neostigmine reversed hemi-diaphragm weakness caused by the three isomers and rocuronium, but not succinylcholine. In electrophysiologic recordings of currents through acetylcholine receptor channels, the carborane compounds did not activate channel activity but did inhibit channel activation by acetylcholine. These results demonstrate that the carborane neuromuscular blocking agents are non-depolarizers in contrast to the depolarizing action of the parent compound.     

The HLD Study of Surfactant Partitioning for Oilfield Corrosion Inhibitors

The partitioning of corrosion inhibitor (CI) products is a measure of their potential to protect oilfield pipelines. In this paper the hydrophilic–lipophilic deviation (HLD) model is first used to quantify their partitioning in terms of the characteristic curvature (C _c,act) of a series of anionic (alkoxylated phosphate esters) and cationic (alkoxylated amines, aromatic amines, imidazoline acetates and quaternary amines) actives. This parameter is expressed over a range of pHs within which pipeline corrosion occurs. The HLD model is next used to predict the partitioning of each active from water into toluene at increased salinities. Linear mixing rules are lastly used to predict the characteristic curvature of Product A (C _c,mix) as a function of the C _c,act of a subset of actives.     

The Inference of Perceived Usability From Beauty

A review of 15 papers reporting 25 independent correlations of perceived beauty with perceived usability showed a remarkably high variability in the reported coefficients. This may be due to methodological inconsistencies. For example, products are often not selected systematically, and statistical tests are rarely performed to test the generality of findings across products. In addition, studies often restrict themselves to simply reporting correlations without further specification of underlying judgmental processes.

The present study's main objective is to re-examine the relation between beauty and usability, that is, the implication that “what is beautiful is usable.” To rectify previous methodological shortcomings, both products and participants were sampled in the same way and the data aggregated both by averaging over participants to assess the covariance across ratings of products and by averaging over products to assess the covariance across participants. In addition, we adopted an inference perspective to qualify underlying processes to examine the possibility that, under the circumstances pertaining in most studies of this kind where participants have limited experience of using a website or product, the relationship between beauty and usability is mediated by goodness.

A mediator analysis of the relationship between beauty, the overall evaluation (i.e., “goodness”) and pragmatic quality (as operationalization of usability) suggests that the relationship between beauty and usability has been overplayed as the correlation between pragmatic quality and beauty is wholly mediated by goodness. This pattern of relationships was consistent across four different data sets and different ways of data aggregation. Finally, suggestions are made regarding methodologies that could be used in future studies that build on these results.     

Error Analysis for a Hybridizable Discontinuous Galerkin Method for the Helmholtz Equation

Finite element methods for acoustic wave propagation problems at higher frequency result in very large matrices due to the need to resolve the wave. This problem is made worse by discontinuous Galerkin methods that typically have more degrees of freedom than similar conforming methods. However hybridizable discontinuous Galerkin methods offer an attractive alternative because degrees of freedom in each triangle can be cheaply removed from the global computation and the method reduces to solving only for degrees of freedom on the skeleton of the mesh. In this paper we derive new error estimates for a hybridizable discontinuous Galerkin scheme applied to the Helmholtz equation. We also provide extensive numerical results that probe the optimality of these results. An interesting observation is that, after eliminating the internal element degrees of freedom, the condition number of the condensed hybridized system is seen to be almost independent of the wave number.     

Association between cigarette smoking and C-reactive protein in a representative, population-based sample of adolescents.

Although related to inflammatory markers in adults, little is known about the association between cigarette smoking and C-reactive protein (CRP) in adolescent smokers. We examined the association between high-sensitivity CRP (hs-CRP) concentrations and smoking in youth. We used data from a cross-sectional, province-wide survey of a representative sample of youth conducted in Quebec, Canada, in 1999. Data were collected in self-report questionnaires completed by participants and their parents. Participants provided a fasting blood sample, and anthropometric measures were undertaken by trained technicians. The present analysis pertains to 1,501 adolescents aged 13 and 16 years who completed questionnaires and for whom blood samples were available. The independent association between a six-category indicator of smoking status and elevated hs-CRP, defined as a value at least in the 90th percentile of the age- and sex-specific CRP distribution, was assessed in multiple logistic regression analyses controlling for potential confounders. Relative to never-smokers, the odds ratios (95% confidence intervals) for puffers (i.e., never smoked a whole cigarette), those who smoked but not in the past month, light past-month smokers, moderate past-month smokers, and heavy past-month smokers were 1.04 (0.55-1.98), 1.76 (1.06-2.94), 1.39 (0.70-2.76), 2.07 (0.96-4.42), and 2.40 (1.18-4.88), respectively. Our data suggest a positive association between smoking status and elevated CRP in adolescents, and in particular among heavier past-month smokers. Damage related to cigarette smoking may begin soon after tobacco use initiation, reinforcing the preventive message that no level of smoking is safe in youth.     

A comparison of interview and self-report methods for the assessment of borderline personality disorder criteria.

Interview methods are widely regarded as the standard for the diagnosis of borderline personality disorder (BPD), whereas self-report methods are considered a time-efficient alternative. However, the relative validity of these methods has not been sufficiently tested. The current study used data from the Collaborative Longitudinal Personality disorder Study to compare diagnostic base rates and the relative validity of interview and self-report methods for assessing functional outcome in BPD. Although self-report yielded higher base rates of criteria endorsement, results did not support the common assumption that diagnostic interviews are more valid than self-reports, but instead indicated the combined use of these methods optimally identifies BPD criteria. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Toxicity characterization of complex mixtures using biological and chemical analysis in preparation for assessment of mixture similarity

In the United States, several proposed approaches for using bioassays for the risk assessment of complex hazardous mixtures require that selected mixtures be "sufficiently similar" to each other. The goal of this research was to evaluate the utility of a protocol using in vitro bioassays and chemical analysis as a basis for assessing mixture similarity. Two wood preserving wastes (WPWs) containing polycyclic aromatic hydrocarbons and pentachlorophenol were extracted and fractionated to generate potentially similar mixtures. Chemical analysis was conducted using gas chromatography/mass spectrometry. Genotoxicity was evaluated using the Salmonella/microsome and Escherichia coli prophage induction assays. The crude extract of one WPW was also tested in the chick embryotoxicity screening test (CHEST) assay. The CHEST assay provided the most sensitive measurement of toxicity. Overall, the biological potency of the samples was not well correlated with predicted potency based on chemical analysis. Although several mixtures appeared similar based on chemical analysis, the magnitude of the response in bioassays was often dissimilar. Fractionation was required to detect the genotoxicity of mixture components in vitro. The results confirm the need for an integrated protocol, combining chemical analysis, fractionation, and biological testing to characterize the risk associated with complex mixtures.     

Activated hopping of the hydroxide ion through electrodeposited thin films of electrochromic cobalt oxyhydroxide

Thin films of cobalt(II) oxyhydroxide on platinum have been prepared by electrodeposition. The chemical diffusion coefficient D of the hydroxide ion through the material has a marked temperature dependence, showing a simple activated behaviour in the range 273–292 K. The activation energy to ionic movement was rather large at 54.5 kJ mol^–1 which, it is proposed, is ascribable to ion hopping. When spins have changed alignment, at the Néel transition temperature T _Nr the activation energy more than doubled to 125 kJ mol^–1; and the diffusion coefficients obtained above this temperature also increased dramatically. It is proposed that structural changes occur in the electrodeposited oxide at about T _Nr hence the change in activation energy.     

A longitudinal examination of computer self-efficacy change trajectories during training

Computer self-efficacy (CSE) is known to enhance individual competence and performance in learning and using technology as well as improve technology attitudes and beliefs. Using longitudinal studies, CSE increases over time during organizational technology training. While these studies have been instrumental in our understanding of how self-efficacy operates in organizations, some critical questions remain unanswered. In particular these studies cannot answer how long it takes for one’s CSE to increase during training, nor can it describe the shape of the change trajectory (linear? some other shape?). The answers to these questions will provide organizations a much clearer perspective on training expectations, understanding when benefits from training through enhanced CSE might be expected, and when to start and ramp up/down training efforts. This study examines these issues by collecting repeated waves of data from 230 respondents in a technology lab training setting and using a relatively new structural equation modeling technique, latent growth modeling. Findings suggest that it takes about 2 months of training for individuals to display significant increases in CSE, and that the growth trajectory for CSE in non-linear. In the proposed model, anxiety is a significant predictor of CSE change, while CSE change significantly predicted software-specific self-efficacies.