Magnetic control system targeted for capsule endoscopic operations in the stomach--design, fabrication, and in vitro and ex vivo evaluations

This paper presents a novel solution of a hand-held external controller to a miniaturized capsule endoscope in the gastrointestinal (GI) tract. Traditional capsule endoscopes move passively by peristaltic wave generated in the GI tract and the gravity, which makes it impossible for endoscopists to manipulate the capsule endoscope to the diagnostic disease areas. In this study, the main objective is to present an endoscopic capsule and a magnetic field navigator (MFN) that allows endoscopists to remotely control the locomotion and viewing angle of an endoscopic capsule. The attractive merits of this study are that the maneuvering of the endoscopic capsule can be achieved by the external MFN with effectiveness, low cost, and operation safety, both from a theoretical and an experimental point of view. In order to study the magnetic interactions between the endoscopic capsule and the external MFN, a magnetic-analysis model is established for computer-based finite-element simulations. In addition, experiments are conducted to show the control effectiveness of the MFN to the endoscopic capsule. Finally, several prototype endoscopic capsules and a prototype MFN are fabricated, and their actual capabilities are experimentally assessed via in vitro and ex vivo tests using a stomach model and a resected porcine stomach, respectively. Both in vitro and ex vivo test results demonstrate great potential and practicability of achieving high-precision rotation and controllable movement of the capsule using the developed MFN.     

An RFID Based Multi-batch Supply Chain Systems

Application of RFID tags had provided a great convenience in supply chain systems. In this paper, an improved version of Cai et al. protocol which was specifically designed for supply chains application is proposed. The Cai et al. RFID system architecture is modified that includes a batch identifier and a path configuration features in order to accommodate multi-batch operation requirements in supply chain systems. Other important requirements in supply chain systems which had been found in relevant articles are also summarized. In addition, requirements of mutual authentication, missing tag identification, and multi-batch operation ability are investigated. We summarize the vulnerabilities of former protocol and propose a new protocol, which employs an  RFID verification scheme, for supply chain systems. Two protocols are presented which included the tags reading protocol with mutual authentication between tags and reader/partner, and the updating protocol (renewing the related secrets). We also modified the handover process and made it more reasonable. The proposed protocol satisfies most of the requirements of supply chain systems and allows multi-batch operation of products. Other merits of our solutions are: collision-free, missing tag identification, and high efficiency. Hence, the overall performance and security of supply chain systems are improved.     

Bright green fluorescence of Asian paper wasp nests

An exceptionally bright fluorescent biomatter was discovered when exploring, with UV-A light, the nests of several oriental paper wasp species of the genus Polistes, a genus of diurnal social insects. Fluorescence spectra of the cocoon cap membranes revealed narrow emission bands in the green range of the visible spectrum. Large Stokes shifts of around 160 nm and high fluorescence quantum yields of up to 35% were measured. Transmission spectra were recorded in order to estimate the contribution of the fluorescence to the visible light transmitted through the cocoon cap membrane. The nest fluorescence of the Vietnamese wasps was compared with a European and an American species. Potential biological functions of these interesting fluorescence properties of the studied biomaterial are discussed. The discovery of this striking example of a fluorescent terrestrial biomaterial may contribute to the debate on adaptive biological functions of natural fluorescence and falls in line with the growing interest in biodiversity and bio-inspiration.     

Optimization of textured structure on crystalline silicon wafer for heterojunction solar cell

Increasing the light scattering in monocrystalline silicon solar cells by surface texturing is an emerging field of practice in modern silicon photovoltaic. In this article, the surface micro-textures were performed on the monocrystalline silicon surface in potassium hydroxide solution without adding isopropyl alcohol. The parameters of the etching process such as concentration, time duration and temperature were examined to study the effects on shape and geometry of the microstructure. In addition, ray-tracing simulations of the light trapping were performed on these textured structures. The textured surfaces resemble the structures of uniform pyramids, mostly small pyramids, and mostly big pyramids. The simulation technique was applied in order to evaluate the light trapping effect by textured surfaces based on above pyramidal shape models. Afterwards, theoretical and experimental values of reflection data were compared. Such a simulation model was perceived as an effective tool for optimizing the micro structural shape, thus improving the light trapping. In this study, for solar cell applications, the double-side heterojunction solar cell with mostly big pyramids shape yielded an active area conversion efficiency of 16.3% with an open circuit voltage of 0.645 V, a short circuit current of 34.8 mA cm⁻² and a fill factor of 0.73.     

Age-related differences in switching between cognitive tasks: Does internal control ability decline with age?

The present study tested the hypothesis that older adults establish a weaker task set than younger adults and therefore rely more on stimulus-triggered activation of task sets. This hypothesis predicts that older adults should have difficulty with task switches, especially when the stimuli-responses are associated with multiple, competing tasks. Weak task preparation, however, could actually benefit older adults when performing an unexpected task. The authors tested this prediction in Experiment 1 using a repeating AABB task sequence, with univalent and bivalent stimuli intermixed. On some univalent trials, participants received an unexpected task. Contrary to the authors' predictions, expectancy costs were not smaller for older adults. Similar findings were obtained in Experiments 2 and 3, in which the authors used a task-cueing paradigm to more strongly promote deliberate task preparation. The authors found no disproportionate age effects on switch costs but did find age effects on bivalence costs and mixing costs. The authors conclude that older adults do experience extra difficulty dealing with stimuli associated with 2 active tasks but found no evidence that the problem specifically stems from an increased reliance on bottom-up task activation rather than top-down task preparation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of acid concentration and current density on DC etching of aluminum electrolytic capacitor foil

This work studies the effects of acid concentration and current density on etching morphology, microstructure and static capacity of the aluminum foils used in high-voltage electrolytic capacitors. The behavior associated with electrochemical etching was investigated with a potentiostat. The aluminum etching type of DC etching is greatly influenced by the etching potential. The static capacity increased to 0.65 uF/cm² with 540 V forming voltage by optimization of the etching parameters used in this work.     

A 78-114 GHz monolithic subharmonically pumped GaAs-based HEMTdiode mixer

A W-band subharmonically pumped (SHP) diode mixer is designed for fixed LO frequency operation. It is fabricated on a 4-mil substrate using 0.15 μm GaAs PHEMT MMIC process. The on-wafer measurement results show that the conversion loss is about 10 to 14 dB across the W band, as a 10 dBm 48 GHz LO signal is pumped. To our knowledge, this is the state-of-the-art result on low-conversion-loss wideband MMIC SHP diode mixer. The packaged module measurement shows a similar result. Both the simulation and measurement results are shown to be in good agreement     

Goal orientations,leader-leader exchange,trust, and the outcomes of project performance

Previous research demonstrates the importance of goal orientation, leader-leader exchange, and trust in work engagement and performance. However, how the relationships among these three variables influence project performance remains unclear. Complementing and extending prior research, this study uncovers how leader-leader exchange and trust affect the relationship between goal orientations and project performance. A cross-sectional analysis of 320 auditing project managers from 50 financial service companies shows that leader-leader exchange and trust mediate how goal orientations influence project performance. We also find that trust further moderates the effect of leader-leader exchange on project performance. Subsequent quantitative analysis of structural equation modeling reveals that leader-leader exchange has the largest direct effect on project performance; team-mastery goal orientation has the second-largest direct effect but the largest total effect. Implications for research and practice are discussed.