Gender differences in the circadian variations in muscle strength assessed with and without superimposed electrical twitches

The circadian rhythm in muscle strength was analysed in 12 males (28 +/- 4 years, 79.6 +/- 12.3 kg, 1.80 +/- 0.05 m) and eight females (28 +/- 4 years, 60.3 +/- 5.5 kg, 1.61 +/- 0.08 m). After two familiarization sessions, participants were tested at six different times of the day (02:00, 06:00, 10:00, 14:00, 18:00 and 22:00 hours), the order of which was randomly assigned over 3-4 days. Rectal temperature (T(rec)) was measured over 30 min before each test. Peak isokinetic torques (PT) of knee extensors and flexors were then measured at 1.05 rad s(-1) and 3.14 rad s(-1) through a 90 degrees range of motion. Maximal isometric voluntary contraction (MVC) of knee extensors and flexors was measured at 60 degrees of knee flexion and the MVC of knee extensors was also assessed with superimposed electrical twitches (50 Hz, 250 V, 200 mus pulse width) in order to control for motivational effects. Three trials were performed in each condition, separated by 3 min recovery, and the highest values were retained for subsequent analyses. A significant circadian rhythm was observed for T(rec) in both males and females (acrophase, Phi, 17:29 and 16:40 hours; mesor, Me, 37.0 and 36.8 degrees C; amplitude, A, 0.28 and 0.33 degrees C for males and females, respectively). The mesor of T(rec) was higher in males than in females (p < 0.05). Significant circadian rhythms were observed for knee extensor PT at 3.14 rad s(-1) in males (Phi, 17:06 hours; Me, 178.2 N m; A, 4.7 N m) and for knee extensor PT at 1.05 rad s(-1) in females (Phi, 15:35 hours; Me, 128.7 N m; A, 3.7 N m). In males, the MVC of knee extensors demonstrated a significant circadian rhythm, but only when electrical twitches were superimposed (Phi, 16:17 h; Me, 302.1 N m; A, 13.6 N m). Acrophases of all indices of muscle strength were not statistically different between the two groups and were located in the afternoon (12:47 < Phi < 17:16 hours). The amplitude (percentage of mesor) of extensors MVC (electrically stimulated) was higher in males (6.4%) than in females (4.2%; p < 0.05). Significant circadian rhythms were not consistently observed for all indices of muscle strength whatever the gender. Our group of female subjects tended to show lower circadian amplitudes than the males. In males, maximal voluntary contraction of electrically stimulated muscles followed a circadian curve, which was not significant without the superimposed twitches. These results suggest that motivation could have a masking effect on the circadian rhythm in muscle performance and strengthen the view that peripheral factors are implicated in this rhythm.     

Determination of trap cross-section in a-Si:H p-i-n diodes parameters using simulation and parameter extraction

Modeling the current density–voltage (J–V) curve of a-Si:H p-i-n diodes requires a group of input physical parameters that have to be previously determined. Some of them can be determined directly from experiment, while others, as the trap cross-section, have to be indirectly determined or assigned. We present a simple procedure to estimate trap cross-section using computer simulation and parameter extraction. The experimental J–V forward characteristic of the p-i-n diode, dark and illuminated, is used to determine the ideality factor n and the short circuit current density J_SC. The charged trap cross-section and its relation to the neutral trap cross-section are determined by fitting to tabulated and graphical results from simulation. Determined values of trap cross-section are used to simulate the reverse current of diodes under illumination and results compared with experimental curves.     

Composition and treatment of effluent from shale gas production

Clean Technologies and Environmental Policy - The expansion of shale gas production requires characterization and correct management of the residues generated by the activity, due to their high...     

Biofilm responses to ageing and to a high phosphate load in a bench-scale drinking water system

The effects of ageing and of phosphate load on drinking water biofilms developed on a polycarbonate substratum in the pseudo-equilibrium state have been evaluated. Phosphate was added in an amount higher than the stochiometric nutrient requirements of bacteria, at concentrations commonly applied in a drinking water distribution system for corrosion control. Multiple parameters were monitored: heterotrophic plate counts (HPCs), total direct counts (TDCs) and potential exoproteolytic activity (PEPA) in order to characterise changes in bacterial biofilms. The total carbohydrate, amino acid and phosphate contents of biofilms were analysed to characterise and monitor the biochemical composition of the biofilm.The three enumeration methods showed that a pseudo-equilibrium state was reached after 7 weeks of colonisation after which, the bacterial growth rate in the biofilm was 0.1 log per week on average. Bulk phosphate addition doubled the phosphate in the biofilm, but did not affect the other biological, physiological or chemical parameters measured.Polysaccharides increased in the biofilm with ageing and the dynamics of individual carbohydrate synthesis also varied with the age of the biofilm. Once pseudo-equilibrium, it was found that the total proteins were globally constant, whereas the spectra of some individual amino acids of the proteins had significantly changed.     

Singular value decomposition-based wave extraction in axial transmission: application to cortical bone ultrasonic characterization

A singular value decomposition-based extraction algorithm is designed in order to recover the group velocity of an energetic contribution measured with an axial transmission device developed previously for cortical bone assessment. Its performance is evaluated on synthetic data mimicking in vivo signals, and it is compared with classical methods.     

Are DTTO and iso‐DTTO Worthwhile Targets for Synthesis?

Theoretical calculations were carried out for the isomeric di‐1,2,3,4‐tetrazine tetraoxides (DTTO and iso‐DTTO). The most important explosion performance parameters, the detonation pressure and detonation velocity, are dominated by the densities and not by the heats of formation of these compounds. Since DTTO and iso‐DTTO are unknown, reliable predictions of their crystal densities are crucial for an evaluation of the potential of these materials as explosives. In this study, the crystal densities were predicted using both Ammon’s Atom/Functional Group and Atom Code Volume Additivity Parameters and Quantum Mechanical molecular Volume methods, resulting in similar densities and explosion parameters. Although the likely uncertainties in our predicted density values are difficult to assess due to a lack of experimental data for closely related known compounds, our results demonstrate that Shechter’s originally proposed densities and performance parameters were grossly overestimated. Furthermore, it is shown that, based on our predicted density value ranges, DTTO and iso‐DTTO could match or substantially outperform the best state of the art explosives, such as CL‐20. Therefore, the synthesis of DTTO and iso‐DTTO should be further pursued.     

An intuitive daylighting performance analysis and optimization approach

The effective integration of daylighting considerations into the design process requires many issues to be considered simultaneously, such as daily and seasonal variations, illumination, and thermal comfort. To address the need for early integration into the design process, a new approach called Lightsolve has been developed. Its key objectives are to support the design process using a goal-oriented approach based on iterative design improvement suggestions; to provide climate-based annual metrics in a visual and synthesized format; and to relate quantitative and qualitative performance criteria using daylighting analysis data in various forms. This methodology includes the development of a time-segmentation process to represent weather and time in a condensed form, the adaptation of daylight metrics that encompass temporal and spatial considerations, and the creation of an interactive analysis interface to explore design options and design iterations. This system relies on optimization techniques to generate these suggestions. Lightsolve allows the designer to explore other design alternatives that may better fulfil the objectives and to learn about appropriate strategies to resolve daylight or sunlight penetration issues. It offers architects and building engineers support for daylighting design that can be employed interactively within the existing design process.

L'intégration des aspects relatifs à l'éclairage naturel dans un projet d'architecture exige l'étude simultanée de nombreuses questions comme ses variations quotidiennes et saisonnières ou l'équilibre entre le niveau d'éclairement et le confort thermique. Afin de répondre à la nécessité d'une intégration rapide dans le processus de conception architecturale, une nouvelle approche baptisée Lightsolve a été mise au point. Ses principaux objectifs sont les suivants: guider le processus par une approche inverse s'appuyant sur des suggestions itératives d'amélioration du projet; fournir des paramètres annuels basés sur le climat sous forme visuelle et synthétique; mettre en relation les critères de performance quantitatifs et qualitatifs en utilisant diverses formes de données d'analyse d'éclairage naturel. Cette méthodologie inclut le développement d'un processus de segmentation temporelle permettant de représenter les conditions météorologiques ainsi que la date ou l'heure sous forme condensée; elle permet également d'englober des considérations temporelles et spatiales pour l'éclairage naturel et comprend la création d'une interface d'analyse interactive pour explorer les options et les itérations du projet dans sa phase conceptuelle. Ce système repose sur des techniques d'optimisation qui génèrent des suggestions de modifications. La méthode Lightsolve permet ainsi au concepteur d'explorer d'autres alternatives pour son projet, susceptibles de mieux atteindre les objectifs visés et de s'informer sur des stratégies appropriées permettant de résoudre des problèmes d'éclairage naturel et de penetration de la lumière directe du soleil. Elle offre aux architectes et aux ingénieurs en bâtiments une aide à la conception en éclairage naturel qui peut être utilisée de manière interactive, afin de ne pas perturber le processus de conception architecturale.

Mots clés: éclairage natural, processus de conception architecturale, aide à la conception, énergie, optimisation interactive, simulation, visualisation     

Late Modernity to Postmodern? The Rise of Global Resilience and its Progressive Potentials for Local Disaster Planning (Seattle and Paris)

ABSTRACT

This paper studies how approaches to disaster planning have been changing with the rise of ‘resilience,’ a concept that has been widely recommended by various international institutions. The critical studies on resilience argue that resilience only serves to legitimise a neoliberal policy agenda that is compatible with a global economic system of capitalism. Contesting that position, this paper argues that the rise of resilience can imply a shift in the mode of governance, and an opportunity for planners to engage with more progressive practices. To make this argument, we propose a ‘postmodern lens’ through which resilience can be seen as an attitude and a style of governance that goes beyond neoliberal assumptions by embracing uncertainty and complexity of governance challenges. Postmodern framing of resilience notes (1) how the concept can initiate a shift in the planner’s view of and practices on knowledges (going beyond ‘expert knowledge’), (2) how the flexibility of the concept can be used for developing political narratives that are progressive (3) how the concept can open up potential venues for nonconventional powers to intervene in policy making processes. To demonstrate how this lens works, we compare the cases of Seattle and Paris, which have drastically different risk governance political structures.     

Conductive polyaniline–polychloroprene blends

The electrical conductivity of polychloroprene (CR)/polyaniline (Pani) blends prepared by bulk and solution processes were investigated. Pani doped with HCl (Pani · HCl) and p-toluenesulfonic acid (Pani · TSA) were employed in vulcanized blends obtained by the bulk process. These blends showed an increase in the conductivity only for blend composition of CR/Pani = 50:50 wt %. At this composition, blends with Pani · HCl and Pani · pTSA presented conductivity values of 10⁻⁹ and 10⁻¹⁰ S · cm⁻¹, respectively. CR/Pani · HCl blend films prepared by the solution process displayed surface conductivity values of 10⁻⁴ S · cm⁻¹ with as low as 10–15 wt % of PAni · HCl. Surface analysis of these blends by X-ray photoelectron spectroscopy indicated no traces of the conductive additive. The surface composition was found to be exclusively constituted of CR. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 1543–1549, 1998