Biosynthesis of volatiles by the myxobacterium Myxococcus xanthus

The volatiles emitted from cell cultures of myxobacterium Myxococcus xanthus were collected by use of a closed-loop stripping apparatus (CLSA) and analyzed by GC-MS. Two new natural products, (S)-9-methyldecan-3-ol ((S)-1) and 9-methyldecan-3-one (2), were identified and synthesized, together with other aliphatic ketones and alcohols, and terpenes. Biosynthesis of the two main components (S)-1 and 2 was examined in feeding experiments carried out with the wild-type strain DK1622 and two mutant strains JD300 and DK11017, which are impaired in the degradation pathway from leucine to isovaleryl-SCoA. Isovaleryl-SCoA is used as a starter, followed by chain elongation with two malonate units. Subsequent use of methyl malonate and decarboxylation leads to (S)-1 and 2. Furthermore, 3,3-dimethylacrylic acid (DMAA) can be used by the mutant strain to form isovaleryl-SCoA, which corroborates recent data on the detection of a novel variety of the mevalonate pathway giving rise to isovaleryl-SCoA from HMGCoA.     

Epistemological beliefs, interest, and gender as predictors of Internet-based learning activities

We examined the contribution of epistemological beliefs, individual interest, and gender to self-reports of Internet-based learning activities in a sample of 80 Norwegian student teachers in an innovative pedagogical context with special emphasis on the use of information and communication technologies. Epistemological beliefs and individual interest were measured in the autumn term of the first year of the teacher education program, and learning activities were measured in the autumn term of the second year. The results indicated that epistemological beliefs about the speed of knowledge acquisition predicted Internet-search activities, with students who believed that learning occurs quickly or not at all being less likely to realize that managing the wealth of information found on the Internet and critically evaluating Web-based resources is a difficult and often time-consuming task. In addition, students who held the naive epistemological belief that knowledge is given and stable were less likely to engage in discussion and communication about subject content on the Internet, with such Internet-based communication also predicted by students’ interest in their field of study. Epistemological beliefs predicting Internet-communication activities were also found to predict self-reported use of strategies when learning from conventional printed texts. Finally, males reported higher levels of participation in Internet-based communication activities than females, and females reported higher levels of strategy use when learning from conventional printed texts than males.     

Fused Deposition Modeling for Unmanned Aerial Vehicles (UAVs): A Review

Additive Manufacturing (AM) is a game changing production technology for aerospace applications. Fused deposition modeling is one of the most widely used AM technologies and recently has gained much attention in the advancement of many products. This paper introduces an extensive review of fused deposition modeling and its application in the development of high performance unmanned aerial vehicles. The process methodology, materials, post processing, and properties of its products are discussed in details. Successful examples of using this technology for making functional, lightweight, and high endurance unmanned aerial vehicles are also highlighted. In addition, major opportunities, limitations, and outlook of fused deposition modeling are also explored. The paper shows that the emerge of fused deposition modeling as a robust technique for unmanned aerial vehicles represents a good opportunity to produce compact, strong, lightweight structures, and functional parts with embedded electronic.

     

Crossed zinc oxide nanorods for ultraviolet radiation detection

An ultraviolet photosensor has been successfully constructed by the in situ lift-out method in a focused ion beam system. The prototype consists of individual naturally self-assembled crossed ZnO nanorods grown by an aqueous solution process. The current–voltage (I–V) characteristics show linear behavior. The photosensor exhibits a response of 15 mA/W for UV light (361 nm) under 1 V bias. Response measurements showed that such a photosensor is suitable for low levels of ultraviolet detection. The method is simple, rapid and applicable to research prototypes for further studies of crossed ZnO nanorods for nano-device applications.     

Parameter Learning in Object-Oriented Bayesian Networks

This paper describes a method for parameter learning in Object-Oriented Bayesian Networks (OOBNs). We propose a methodology for learning parameters in OOBNs, and prove that maintaining the object orientation imposed by the prior model will increase the learning speed in object-oriented domains. We also propose a method to efficiently estimate the probability parameters in domains that are not strictly object oriented. Finally, we attack type uncertainty, a special case of model uncertainty typical to object-oriented domains.     

Automatic multi-modal intelligent seizure acquisition (MISA) system for detection of motor seizures from electromyographic data and motion data

The objective is to develop a non-invasive automatic method for detection of epileptic seizures with motor manifestations. Ten healthy subjects who simulated seizures and one patient participated in the study. Surface electromyography (sEMG) and motion sensor features were extracted as energy measures of reconstructed sub-bands from the discrete wavelet transformation (DWT) and the wavelet packet transformation (WPT). Based on the extracted features all data segments were classified using a support vector machine (SVM) algorithm as simulated seizure or normal activity. A case study of the seizure from the patient showed that the simulated seizures were visually similar to the epileptic one. The multi-modal intelligent seizure acquisition (MISA) system showed high sensitivity, short detection latency and low false detection rate. The results showed superiority of the multi-modal detection system compared to the uni-modal one. The presented system has a promising potential for seizure detection based on multi-modal data.     

Observations and hypothesis of double stall

The double-stall phenomenon of aerofoil flows is characterized by at least two distinct stall levels for identical inflow conditions. In the present work a likely explanation of double stall is presented. Observations on full-scale rotors, in wind tunnel experiments and in CFD calculations could show at least two different distinct lift levels for identical inflow conditions, with sudden shifts between them. CFD calculations revealed the generation of a small, laminar separation bubble at the leading edge of the aerofoil for incidences near maximum lift. The bursting of this bubble could explain the sudden shift in lift levels. This investigation indicated that bursting will occur if the position of the free transition is only a small distance upstream from the position where forced transition would first cause leading-edge stall. Thus the investigation indicated that double stall is closely related to the actual geometry of the leading edge of the aerofoil and that it probably can be avoided in the design of new aerofoils. The investigation indicated further that double stall can be predicted from CFD calculations. Copyright © 1999 John Wiley & Sons, Ltd.     

Pharmaceuticals and personal care products (PPCPs) in surface and treated waters of Louisiana,USA and Ontario,Canada

A newly developed analytical method was used to measure concentrations of nine pharmaceuticals and personal care products (PPCPs) in samples from two surface water bodies, a sewage treatment plant effluent and various stages of a drinking water treatment plant in Louisiana, USA, and from one surface water body, a drinking water treatment plant and a pilot plant in Ontario, Canada. The analytical method provides for simultaneous extraction and quantification of the following broad range of PPCPs and endocrine-disrupting chemicals: naproxen; ibuprofen; estrone; 17beta-estradiol; bisphenol A; clorophene; triclosan; fluoxetine; and clofibric acid. Naproxen was detected in Louisiana sewage treatment plant effluent at 81-106 ng/l and Louisiana and Ontario surface waters at 22-107 ng/l. Triclosan was detected in Louisiana sewage treatment plant effluent at 10-21 ng/l. Of the three surface waters sampled, clofibric acid was detected in Detroit River water at 103 ng/l, but not in Mississippi River or Lake Pontchartrain waters. None of the other target analytes were detected above their method detection limits. Based on results at various stages of treatment, conventional drinking-water treatment processes (coagulation, flocculation and sedimentation) plus continuous addition of powdered activated carbon at a dosage of 2 mg/l did not remove naproxen from Mississippi River waters. However, chlorination, ozonation and dual media filtration processes reduced the concentration of naproxen below detection in Mississippi River and Detroit River waters and reduced clofibric acid in Detroit River waters. Results of this study demonstrate that existing water treatment technologies can effectively remove certain PPCPs. In addition, our study demonstrates the importance of obtaining data on removal mechanisms and byproducts associated with PPCPs and other endocrine-disrupting chemicals in drinking water and sewage treatment processes.     

Antiproton therapy

Radiotherapy is one of the most important means we have for the treatment of localised tumours. It is therefore essential to optimize the technique, and a lot of effort goes into this endeavour. Since the proposal by Wilson in 1946 [R.R. Wilson, Radiology use of fast protons, Radiology 47 (1946) 487.] that proton beams might be better than photon beams at inactivating cancer cells, hadron therapy has been developed in parallel with photon therapy and a substantial knowledge has been gained on the effects of pions, protons and heavy ions (mostly carbon ions). Here we discuss the recent measurements by the CERN ACE collaboration of the biological effects of antiprotons, and argue that these particles very likely are the optimal agents for radiotherapy.