Dielectric Tunability of DNA Biopolymer Films with Varying Amounts of Hexadecyltrimethylammonium Chloride

Deoxyribonucleic acid (DNA) biopolymer films are fabricated with varying amounts of hexadecyltrimethylammonium chloride (CTMA), which is a surfactant necessary to produce a DNA complex that is soluble in organic solvents. The dielectric constant (κ) of these films at microwave frequencies as a function of applied static electric field (E _DC) is investigated. Results show that the dependence of κ on E _DC, which is referred to as the dielectric tunability, is influenced by the amount of CTMA in the complex. Dielectric tunability is suppressed when the amount of CTMA is insufficient and improved when more CTMA is added. However, excessive amounts of CTMA also result in a very rough film surface that causes shorting problems when used in a capacitive structure. A varactor employing a 1-μm-thick DNA biopolymer film as the dielectric is demonstrated. Under 5 V DC bias, which generates E _DC = 5 V/μm, its capacitance at 15 GHz changes by 0.04 pF. This change corresponds to a relative dielectric tunability of 6.6%. A simple application of this varactor for modulation of the power transmitted through a microwave transmission line is also demonstrated.     

Sub-lethal stress effects on virulence gene expression in Enterococcus faecalis

Enterococci are ubiquitous lactic acid bacteria commonly associated with the human digestive tract as commensal organisms. Additionally, these organisms have a long history of use in foods improving flavor as well as providing protective mechanisms as either a probiotic or antimicrobial additive. However, Enterococcus faecalis accounts for up to 10% of all nosocomial infections of the bloodstream, wounds, urinary tract and heart. Knowledge about the regulation of virulence factors is limited and the involvement of environmental signals contributing to E. faecalis pathogenicity is poorly documented. In this study, two clinical E. faecalis isolates, TMW 2.63 and OG1RF, as well as one food isolate, TMW 2.629, were subjected to six sub-lethal food- and host-related stresses including 6.8% NaCl, 200 ppm nitrite, 51 °C, 80 MPa, pH 4.1 and 0.08% bile salts (cholic acid:chenodeoxycholic acid 1:1), respectively, reducing their growth rate to 10%. Relative gene expression of 15 stress and virulence-associated genes including dnaK, groEL, ctsR, clpPBCEX, gls24, efaAfs, ace, fsrB, gelE, sprE and cylB, was quantified by using real time PCR and Lightcycler^® technology (reference conditions: BHI broth, 37 °C, pH = 7.4). Apart from strain-dependent differences, sub-lethal environmental stress was capable of provoking significant alterations in the expression of virulence-associated genes in E. faecalis from clinical as well as food origins of isolation. These results help to avoid preconditioning enterococci in food production processes and to understand the complex mechanisms in E. faecalis' switch to pathogenicity.     

Evidence and a computational explanation of cultural differences in facial expression recognition.

Facial expressions are crucial to human social communication, but the extent to which they are innate and universal versus learned and culture dependent is a subject of debate. Two studies explored the effect of culture and learning on facial expression understanding. In Experiment 1, Japanese and U.S. participants interpreted facial expressions of emotion. Each group was better than the other at classifying facial expressions posed by members of the same culture. In Experiment 2, this reciprocal in-group advantage was reproduced by a neurocomputational model trained in either a Japanese cultural context or an American cultural context. The model demonstrates how each of us, interacting with others in a particular cultural context, learns to recognize a culture-specific facial expression dialect. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conditioning-specific reflex modification of rabbit (oryctolagus cuniculus) heart rate.

Conditioning-specific reflex modification (CRM) describes changes in rabbit (Oryctolagus cuniculus) nictitating membrane responses (NMR) to an unconditioned stimulus (US) when the US is tested by itself after pairings of tone and electrodermal stimulation. Although CRM has been replicated, it is unclear whether it occurs in response systems other than that of the NMR. The authors report that CRM of rabbit heart rate (HR) can occur following HR conditioning. A US that elicits HR acceleration before conditioning can elicit HR deceleration after conditioning. The rabbits' electrocardiograms showed both HR conditioning and HR CRM were correlated with an increased PQ interval--an index of parasympathetic function mediated by the vagus. The data suggest conditioned HR deceleration can generalize from conditioned stimulus to US as a function of conditioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Organizational Divisions in BIM-Enabled Commercial Construction

Proponents claim that the adoption of building information modeling (BIM) will lead to greater efficiencies through increased collaboration. In this paper, we present research that examines the use of BIM technologies for mechanical, electrical, plumbing, and fire life safety systems (often referred to as MEP) coordination and how the introduction of BIM influences collaboration and communication. Using data from over 12 months of ethnographic observations of the MEP coordination process for two commercial construction projects and interviews with 65 industry leaders across the United States, we find that BIM-enabled projects are often tightly coupled technologically, but divided organizationally. This means that while BIM makes visible the connections among project members, it is not fostering closer collaboration across different companies. We outline the competing obligations to scope, project, and company as one cause for this division. Obligations to an individual scope of work or to a particular company can conflict with project goals. Individual leadership, especially that of the MEP coordinator in the teams we studied, often substitutes for stronger project cohesion and organization. Organizational forces and structures must be accounted for in order for BIM to be implemented successfully.     

Review of the TAIFUN® Multidose Dry Powder Inhaler Technology

Although pressurized metered dose inhalers (pMDIs) currently constitute a majority of the market share in the inhalation market, dry powder inhaler (DPI) products have become increasingly popular due to their reliability and product performance. One such DPI is the TAIFUN® inhaler that is a reservoir-based DPI system with the ability to produce consistent and uniform doses in vitro. Originally developed for the pulmonary delivery of salbutamol, the TAIFUN® inhaler platform has since been used to develop a product for breakthrough cancer pain management using fentanyl citrate as the active drug. In vivo results show the TAIFUN® inhaler is able to deliver a rapid onset of action and increased relative bioavailability compared with other fentanyl products currently on the market.     

Prognostic implications of clinical practice guidelines among hemodialysis patients

Although the National Kidney Foundation (NKF) has published clinical practice guidelines for the management of risk factors for cardiovascular disease, these guidelines have not been tested rigorously for their effectiveness. We conducted an observational study among patients with end-stage kidney disease to examine the prognostic impact of threshold levels recommended by the NKF for blood pressure, hemoglobin, calcium-phosphate product, parathyroid hormone, low-density lipoprotein, and glycosylated hemoglobin. The study population (N = 197) was assembled from a previously completed randomized trial examining arteriovenous graft thrombosis. Cox proportional hazard analysis was used to calculate hazard ratios for the association of levels outside guideline recommended targets and death, adjusting for age, comorbidity, race, and albumin. The proportion of patients outside guideline targets ranged from 33% to 81%, and the impact of levels outside guideline targets on mortality varied substantially. Elevated calcium-phosphate product and glycosylated hemoglobin had harmful effects, with adjusted hazard ratios of 1.58 (95% CI 1.00-2.50; p = 0.050) and 2.21 (95% CI 0.99-4.97; p = 0.054), respectively. Nontarget levels for blood pressure, hemoglobin, and parathyroid hormone had little effect, with adjusted hazard ratios of 1.15 (95% CI 0.74-1.78; p = 0.542), 1.04 (95% CI 0.65-1.68; p = 0.866), and 0.90 (95% CI 0.50-1.61; p = 0.722), respectively. Elevated low-density lipoprotein had a paradoxically beneficial effect, with an adjusted hazard ratio of 0.48 (95% CI 0.23-1.00; p = 0.049). These results suggest that the prognostic impact of current threshold levels recommended by select NKF guidelines on mortality is variable. Accordingly, the development and implementation of clinical practice guidelines should be accompanied by corresponding efforts to confirm their impact on patient outcomes. Such efforts are essential for the improvement of guidelines and to inform health policy optimally.