Capacitive microphone with a surface micromachined backplate usingelectroplating technology

A technology for surface micromachining of free-standing metal microstructures using metal electrodeposition on a sacrificial photoresist layer has been applied to a condenser microphone. Electroplating technology has been used to implement a suspended and perforated 15-μm-thick microstructure in copper, which serves as backplate electrode in the condenser microphone. The 1.8×1.8 mm ² large microphone diaphragm is in monocrystalline silicon and is fabricated with anisotropic etching of the substrate wafer. The realized prototypes have a measured sensitivity of 1.4 mV/Pa using a bias voltage of 28 V. The bandwidth is limited by an anti-resonance at 14 kHz which is due to the semi-rigid backplate. The resonance behavior of the backplate structure has been analyzed with finite element modeling with results in good agreement with measured data     

Failure to differentiate Cryptosporidium parvum from C. meleagridis based on PCR amplification of eight DNA sequences

PURPOSE: Little is known about the developmental effects of high urinary diversion and bladder defunctionalization in infancy. Although clinical experience shows that a poorly functional bladder may result from urinary diversion in infancy, the mechanisms of change and specific bladder wall alterations have not been well characterized. We hypothesized that cyclic filling and emptying are necessary for normal bladder development. To investigate this important question we created a new animal model. MATERIALS AND METHODS: We designed a new method of hemibladder urinary diversion in 3-week-old New Zealand white rabbits. After vertical midline bladder division half of the bladder was formed into a functional reservoir, which remained in continuity with the ipsilateral ureter and urethra. The other bladder half was defunctionalized and isolated from the urine flow by ureteral ligation. Diversion was created for 3, 7, 14 and 28 days. Urodynamic evaluation was done in the functionalized hemibladders and age matched normal rabbit bladders to test the validity of the functionalized hemibladder as an internal control. Functional and defunctionalized hemibladders as well as age matched, nonoperated normal rabbit bladders were weighed, sectioned and stained to demonstrate muscle and connective tissue components. RESULTS: In 22 of the 27 healthy rabbits (81%) good quality diverted and functional bladder specimens were obtained after diversion. Defunctionalized hemibladders grew more slowly than functionalized bladders and normal age matched control bladders. Histological staining of the bladder wall demonstrated increased connective tissue between the muscle bundles within the diverted specimens than in functional bladders. CONCLUSIONS: Our successful model of urinary diversion may be used to study the developmental and histological effects of urinary diversion in the young bladder. Bladder growth and histological appearance are altered when the stimulus of cyclic filling and emptying is removed. Further studies using this model are warranted to define fully bladder changes that result from diversion and investigate the mechanism of the observed changes.     

Expertise and Intuition: A Tale of Three Theories

Several authors have hailed intuition as one of the defining features of expertise. In particular, while disagreeing on almost anything that touches on human cognition and artificial intelligence, Hubert Dreyfus and Herbert Simon agreed on this point. However, the highly influential theories of intuition they proposed differed in major ways, especially with respect to the role given to search and as to whether intuition is holistic or analytic. Both theories suffer from empirical weaknesses. In this paper, we show how, with some additions, a recent theory of expert memory (the template theory) offers a coherent and wide-ranging explanation of intuition in expert behaviour. It is shown that the theory accounts for the key features of intuition: it explains the rapid onset of intuition and its perceptual nature, provides mechanisms for learning, incorporates processes showing how perception is linked to action and emotion, and how experts capture the entirety of a situation. In doing so, the new theory addresses the issues problematic for Dreyfus’s and Simon’s theories. Implications for research and practice are discussed.

Low-passband-sensitivity switched capacitor filters using a parallel connection of two structurally lossless networks

The low-sensitivity property of IIR digital filters designed using a parallel connection of two allpass sections has already been demonstrated in the past few years. This property is closely related to the use of a particular type of allpass structures, called structurally lossless networks, which remain allpass regardless of the coefficient quantization. In this paper we provide a general theory for the synthesis of low-passband-sensitivity switched capacitor (SC) filters using a similar technique. the design of stray-insensitive structurally allpass SC sections is emphasized, ensuring the passivity property for the overall filter. Design examples are presented with computer simulations and experimental results to compare the performance of the different proposed structures. Analytical sensitivity calculations are also derived yielding useful formulae for the prediction of the filter sensitivities with respect to capacitor ratios, particularly in the stopband.     

Solar energy and global heat balance of a city

The global energy balance of a city involves numerous energy flows and is rather complex. It includes, among others, the absorbed solar radiation and the energy fuels on one hand, and the heat loss to the environment — by radiation, convection and evaporation — on the other hand. This balance generally results in a temperature in the town that is slightly higher than in the surrounding country. Using solar energy saves imported fuels on one hand, but increases the absorption of solar radiation on the other hand. Simple, steady state models are used to assess the change of heat released to the environment when replacing the use of classical fuels by solar powered plants, on both the global and city scale. The conclusion is that, in most cases, this will reduce the heat released to the environment. The exception is cooling, for which a good solar alternative does not exist today.     

Operating conditions for the electrolytic disinfection of process wash water from the fresh-cut industry contaminated with E. coli o157:H7

The effect of operating conditions (current density, recirculation flow rate and electrode doping level) on the efficacy of boron-doped diamond (BDD) electrodes to inactivate microorganisms and decrease chemical oxygen demand (COD) was studied in lettuce process wash water with a COD of 725 mg/L and inoculated with a 5-strain cocktail of Escherichia coli O157:H7. Changes in pathogen population, COD, pH, temperature, redox potential, and free and total chlorine were monitored in process wash water during treatments. Considering the specific characteristics of the washing step included in the fresh-cut processing, the disinfection of process wash water should be of fast action. A biphasic with a shoulder model was used to estimate shoulder length (Sl), log-linear inactivation rates (k_max1, k_max2), lowest population (N_f) and highest log reduction (HLR). Current density clearly influenced Sl, and k_max2; recirculation flow rate influenced Sl, k_max1, k_max2 and COD depletion; and doping level influenced N_f. No relationship was observed between inactivation parameters and chlorine concentration. Conditions including high current density (180 mA/cm²), high flow rate (750 l/h) and high doping level (8 000 μmol/mol) seems to provide a disinfection efficiency suitable to decrease the chance of bacterial cross contamination in the fresh-cut industries while saving on water consumption and decreasing the amount of wastewater effluents.     

Urethroplasty of the free colonic mucosa in rats. Preliminary study of the use of appendicular mucosa

The various tissues used as free grafts in urethroplasties are associated with a high incidence of fistulae and strictures. The search for a new, more effective substitute had led the authors to study the possibility of using a new type of mucosa: appendicular mucosa. The size and cylindrical structure of the appendix and its easy resection make it an original and adapted urethral substitute. As most animals do not possess an appendix, an animal model of urethroplasty with colic mucosa has been used. A segmental distal urethrectomy has been performed on 40 rats, 14 had a simple urethral stent without any urethroplasty (Group I), for 7 wi performed the urethroplasty with a collagen tube (Group II) and for 19 an urethroplasty with free colic mucosa was performed (Group III), 3 to 6 weeks later, a macroscopic and microscopic study were realised. In group I and II the urethral duct developed a fibrosis and all rats had a severe stenosis when the stent went out. In those two groups, a urinary fistula has been developed in all rats except one. In group III, a neo-urethra was found. Under light microscopic examination a typical urothelium was observed in the mid and distal section and a keratinized squamous epithelium on the distal section. The results of the preliminary study let us believe that the digestive mucosa may be used for urethroplasty. Before we can propose the appendix mucosa in human surgery, it will be useful to perform sooner histological examination, then the genesis of the neo-urothelium should be understood.     

Expert memory: a comparison of four theories

This paper compares four current theories of expertise with respect to chess players' memory: Chase and Simon's chunking theory, Holding's SEEK theory, Ericsson and Kintsch's long-term working memory theory, and Gobet and Simon's template theory (Chase, W.G., Simon, H.A., 1973a. Perception in chess. Cognitive Psychology 4, 55-81; Holding, D.H., 1985. The Psychology of Chess Skill. Erlbaum, Hillsdale, NJ; Ericsson, K.A., Kintsch, W., 1995. Long-term working memory. Psychological Review 102, 211-245; Gobet, F., Simon, H.A., 1996b. Templates in chess memory: a mechanism for recalling several boards. Cognitive Psychology 31, 1-40). The empirical areas showing the largest discriminative power include recall of random and distorted positions, recall with very short presentation times, and interference studies. Contrary to recurrent criticisms in the literature, it is shown that the chunking theory is consistent with most of the data. However, the best performance in accounting for the empirical evidence is obtained by the template theory. The theory, which unifies low-level aspects of cognition, such as chunks, with high-level aspects, such as schematic knowledge and planning, proposes that chunks are accessed through a discrimination net, where simple perceptual features are tested, and that they can evolve into more complex data structures (templates) specific to classes of positions. Implications for the study of expertise in general include the need for detailed process models of expert behavior and the need to use empirical data spanning the traditional boundaries of perception, memory, and problem solving.     

Simplification of genetic programs: a literature survey

Data Mining and Knowledge Discovery - Genetic programming (GP), a widely used evolutionary computing technique, suffers from bloat—the problem of excessive growth in individuals’ sizes....