The effects of electronic alert letters for internet surveys of academic scientists

Scientometrics - Survey alert letters improve response rates and assure potential respondents that the research is legitimate and of high quality. Pre-notification by mail increases response rates...     

A Liquid‐Metal–Elastomer Nanocomposite for Stretchable Dielectric Materials

Stretchable high‐dielectric‐constant materials are crucial for electronic applications in emerging domains such as wearable computing and soft robotics. While previous efforts have shown promising materials architectures in the form of dielectric nano‐/microinclusions embedded in stretchable matrices, the limited mechanical compliance of these materials significantly limits their practical application as soft energy‐harvesting/storage transducers and actuators. Here, a class of liquid metal (LM)–elastomer nanocomposites is presented with elastic and dielectric properties that make them uniquely suited for applications in soft‐matter engineering. In particular, the role of droplet size is examined and it is found that embedding an elastomer with a polydisperse distribution of nanoscale LM inclusions can enhance its electrical permittivity without significantly degrading its elastic compliance, stretchability, or dielectric breakdown strength. In contrast, elastomers embedded with microscale droplets exhibit similar improvements in permittivity but a dramatic reduction in breakdown strength. The unique enabling properties and practicality of LM–elastomer nanocomposites for use in soft machines and electronics is demonstrated through enhancements in performance of a dielectric elastomer actuator and energy‐harvesting transducer.     

A mixed-integer programming approach for solving university course timetabling problems

Journal of Scheduling - This article presents a mixed-integer programming model for solving the university timetabling problem which considers the allocation of students to classes and the...     

Modeling and iterative learning control of spatially distributed parameter systems with sensing and actuation over a selected area of the domain

Multidimensional Systems and Signal Processing - This paper gives new contributions to the development of iterative learning control for distributed parameter systems, based on using finite...     

Structural analysis of binary executable headers for malware detection optimization

In the context of the OpenDAVFI project (a fork of the French initiative DAVFI for giving birth to a new generation, open antivirus engine which has been funded by the French Government), different AV filters have been developped and chained to detect both known and unknown malware very accurately while requiring a very limited number of updates. While most AV software use different static and dynamic detection techniques which are mostly based on the general concept of (static or heuristic) signature, we have observed that many malware do not comply to the Microsoft specifications with respect to the MZ-PE format. In this technical correspondence, we present structural analysis tests which have been implemented in the DAVFI/OpenDAVFi project. These tests accurately detect malware and therefore greatly reduce the number of malware that have to be analyzed by subsequent modules in our detection chain.     

Simulation of the oxidative dehydrogenation of methanol

The selective air oxidation of methanol over a 96.6% silver -3.4% copper catalyst supported on α-alumina was studied to determine whether by supplying heat from an external source the extent of the dehydrogenation reaction to formaldehyde could be increased relative to the oxidative dehydrogenation route. Preheated reactants were fed over the catalyst which was held in place between glass wool plugs within a 0.16 inch I.D. quartz U-tube. The latter was suspended in an electrically heated bath of fluidized alumina used to maintain constant temperature. Product analyses were made by gas chromatography using a Porapak N column. A mathematical model was designed to simulate the observed results. The results show that with the catalyst employed the addition of heat to supply the requirements of the dehydrogenation reaction and to decrease the extent of the oxidative reaction is not favorable in terms of formaldehyde production efficiency.     

Separation of binary mixtures by dense membrane processes: influence of inert gas entrance under variable downstream pressure conditions

The influence of an inert gas on the separation performances of a dense polymeric membrane module working under partial vacuum on the downstream side, such as possibly encountered in gas permeation, vapor permeation or pervaporation, has been investigated through an experimental and theoretical study. A whole range of situations on the downstream side, covering ideal vacuum pumping (i.e. zero downstream pressure under leak free conditions) to inert gas sweeping under atmospheric pressure has been tested. A theoretical framework, previously developed for single permeant situation has been extended to the multicomponent case. The separation of methanol and 2-propanol by a dense silicone rubber membrane confirms the ability of this simple modelling strategy to offer quantitative predictions of the permeate composition under variable downstream pressure and inert gas flowrate conditions. Based on this observation, the implications of an inert gas contribution on pervaporation or gas separation operation are discussed, particularly in relationship to the global energy consumption of the system or to analytical devices making use of a gas sweep.     

Modelling the polypeptide backbone with 'spare parts' from known protein structures

An automatic procedure for building a protein polyalanine backbonefrom C positions and ‘spare parts’ retrieved froma data base of 66 high-resolution protein structures is described.Protein backbones are constructed from over-lapping fragmentsof variable length, which allows the backbone of regular secondarystructure elements to be built in one block. The procedure isshown to yield backbones which compare very favourably withthose from highly refined X-ray structures (r.m.s. deviationbetween generated and crystal structures <lÅ). Themethod is furthermore quite insensitive to experimental errorsin C positions as well as to the size of the data base, andis seen to yield valuable insight into the relationships betweensequence and 3-D structure: one example on triose phosphateisomerase, a ß-barrel protein, shows that ßloops can be considered as structurally more uncommon than ßloops. The ‘spare parts’ approach is also foundto be useful for general-purpose modelling of local structuralchanges produced by insertion or deletion of residues. It should,however, be used with caution. Crude selection criteria basedsolely on fragment length and geometric fit to the loop baseregions yield realistic backbones in about two-thirds of thetest cases (r.m.s. deviations from refined crystal structure{small tilde}lÅ). In the remaining cases, sequence information,in particular the presence of glycine residues which tend toadopt more unusual backbone conformations, must be consideredto obtain comparable results.     

Retinal fatty acids of piglets fed docosahexaenoic and arachidonic acids from microbial sources

Docosahexaenoic acid (DHA, 22∶6n-3) and arachidonic acid (AA, 20∶4n-6) serve important roles in perinatal visual and neural development. A neonatal pig model was used to determine if dietary supplementation with DHA and AA at slightly greater concentrations than normally found in human milk would influence fatty acid accretion in retina. One-day-old piglets were assigned to one of four diets (n=5/group): (i) STD, standard diet containing fat similar to infant formula; (ii) STD+DHA, 0.7% of fatty acids as DHA; (iii) STD+AA, 0.9% as AA; and (iv) STD+BOTH, 0.8% as DHA plus 1.0% as AA. After 25 d, fatty acids in retina phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were determined. Supplementation with DHA resulted in approximately twofold increases (P<0.05) in PC-DHA (4.88% in STD vs. 10.03% in STD+DHA and 9.47% in STD+BOTH). Similarly, AA supplementation increased PC-AA 1.3–1.4-fold (4.47% in STD vs. 6.19% in STD+AA and 5.70% in STD+BOTH). For PE, supplementation with either fatty acid or in combination resulted in no significant increases, except for a 1.2-fold increase in DHA for STD+BOTH (32.66%) vs. STD (28.38%). Thus, PC responded to dietary supplementation, with addition of DHA, AA, or BOTH, resulting in increases in respective fatty acids; PE was less responsive, with only STD+BOTH resulting in increased DHA. No significant competition between DHA and AA in incorporation into phospholipids was observed. In conclusion, consumption of a combination of DHA and AA by neonatal pigs supported accretion of DHA in retina phospholipids, while simultaneously supplying the AA necessary for membrane phospholipids and eicosanoid biosynthesis. Based on a presentation at the AOCS Annual Meeting & Expo in San Antonio, Texas, May 7–11, 1995.