A tunable switched-capacitor programmable N-path tonereceiver and generator

An integrated full-duplex tone receiver and generator used for signaling in mobile radio systems and realized with a switched-capacitor pseudo N-path technique is described. A receiver filter with a quality factor programmable in the range 10-230 with an in-band loss less than 0.2 dB and center frequencies from 1 Hz up to 10 kHz was achieved. The tone generator of the system was realized with a programmable gain switched-capacitor amplifier that generates an eight-sample pseudo-sine-wave signal. The chip was fabricated using a 3-μm double-poly CMOS process. Its power consumption is 17 mW with a single 5-V supply, and its size is 18 mm²     

Characterization and modeling of silicon integrated spiral inductors for high-frequency applications

This paper presents the characterization and modeling of 0.3- to 0.8-nH radial patterned ground shield circular inductors fabricated in a silicon bipolar technology for RF applications. An extensive validation of measurement accuracy is first addressed taking into account both calibration and de-embedding issues. A novel five-step de-embedding technique is also proposed to improve the accuracy of small inductor measurements. The accuracy of de-embedded experimental data in the range 0.3-0.8 nH is demonstrated by comparing the measured low-frequency inductance with electromagnetic simulations of a large set of inductors. Based on both electromagnetic simulations and experimental measurements, the well-known current sheet expression for circular spirals is revised and modified to improve its accuracy at lower inductance values. The proposed expression is also extended to inductors with polygonal geometries showing significant improvements with respect to the state-of-the-art. Finally, the original and modified expressions are employed in a lumped scalable model for silicon spiral inductors. Comparisons with measured data revealed that the modified expression allows error reductions as large as 20% with respect to the original one, on both inductance and quality factor simulations.     

T c as a Function of Electron Doping in Mg10B2 Using Sc for Mg Substitution

We have studied the variation of superconducting critical temperature T _c as a function of electron doping in the Mg¹⁰B₂ system using Sc for Mg substitution. The critical temperature in the¹⁰B isotope substituted system Mg_{1? x} Sc _x ¹⁰B₂ increases by increasing the scandium content x in the range 0<x<0.012 up to 41.4 K, while the T _c of the natural boron system Mg_{1? x} Sc _x B₂ is nearly constant. The overall difference of T _c in Mg_{1? x} Sc _x B₂ as function of x between the natural B and ¹⁰B isotope system seems to indicate that the isotope effect shows large variations with electron doping as expected for the T _c enhancement driven by a shape resonance.     

Electrosynthesized non-conducting polymers as permselective membranes in amperometric enzyme electrodes: a glucose biosensor based on a co-crosslinked glucose oxidase/overoxidized polypyrrole bilayer

The sperm plasma membrane is segregated into functionally, biochemically, and structurally distinct domains yet the protein sorting pathways and assembly mechanisms that assemble these domains during spermiogenesis are incompletely understood. We previously characterized two structurally related size-variant, integral membrane proteins of 52 kDa (PM52) and 35 kDa localized to the periacrosomal plasma membrane of guinea pig cauda epididymal spermatozoa (Westbrook-Case et al., 1994). In this study we used light and electron microscopic immunocytochemistry to define the expression pattern and sorting pathway that establishes the domain-specific distribution of PM52 during spermiogenesis. The PM52 is first expressed in acrosome-phase spermatids and it localizes exclusively to the cytoplasmic lobe. Immunoelectron microscopy revealed that both cytoplasmic vesicles and the plasma membrane of the cytoplasmic lobe labeled with anti-PM52. During early stages of expression, PM52 appeared to be absent from the head region, but significant PM52 accumulation over the spermatid head was noted in late acrosomal phase spermatids. Throughout spermiogenesis PM52 extended posteriorly to the annulus, which represents a barrier preventing PM52 diffusion into the posterior tail. Following the migration of the annulus to the midpiece-principal piece junction, PM52 began to disappear from the flagellar region and at the completion of spermiogenesis most of the PM52 was restricted to the acrosomal segment. Spermatids and epididymal sperm PM52 exhibited identical sizes by SDS-PAGE and immunoblotting, indicating that they are not proteolytically modified during epididymal maturation. The PM52 antibodies were also used to screen a guinea pig testis cDNA library, and sequence determination of full-length PM52 clones demonstrated identity of a sperm membrane protein recently termed "sperad" (Quill and Garbers, 1996). Membrane barriers and potential mechanisms establishing the domain-specific residence of PM52 are discussed.     

Effects of dynamic field-of-view restriction on cybersickness and presence in HMD-based virtual reality

The phenomenon of cybersickness is currently hindering the mass market adoption of head-mounted display (HMD) virtual reality (VR) technologies. This study examined the effects of dynamic field-of-view (FOV) restriction on the cybersickness generated by ecological HMD-based gameplay. Forty participants were exposed to a commercially available HMD game (Marvel Powers United VR) under both unrestricted FOV and dynamic FOV restriction conditions across three sessions. Participants had their spontaneous postural instability measured before entering VR. Then, during/following each of these 10-min exposures to HMD VR, they rated their cybersickness, vection (illusory self-motion), and feelings of presence. Individual differences in spontaneous postural instability were found to predict cybersickness during HMD VR gameplay. Cybersickness severity increased steadily over the course of each VR exposure and was significantly reduced by dynamic FOV restriction. Presence also increased steadily over the course of each VR exposure and was positively correlated with vection. We conclude that: (1) postural instability can identify people who are more susceptible to cybersickness, (2) vection can increase an HMD user’s feelings of presence, and (3) dynamic FOV restriction can serve as a viable countermeasure to cybersickness.

     

Using Context to Improve Predictive Modeling of Customers in Personalization Applications

The idea that context is important when predicting customer behavior has been maintained by scholars in marketing and data mining. However, no systematic study measuring how much the contextual information really matters in building customer models in personalization applications have been done before. In this paper we study how important the contextual information is when predicting customer behavior and how to use it when building customer models. It is done by conducting an empirical study across a wide range of experimental conditions. The experimental results show that context does matter when modeling the behavior of individual customers and that it is possible to infer the context from the existing data with reasonable accuracy in certain cases. It is also shown that significant performance improvements can be achieved if the context is "cleverly" modeled, as described in the paper. These findings have significant implications for data miners and marketers. They show that contextual information does matter in personalization applications and companies have different opportunities to both make context valuable for improving predictive performance of customers' behavior and decreasing the costs of gathering contextual information.     

Removal of drugs in aqueous systems by photoassisted degradation

Aqueous solutions of tetracycline, lincomycin and ranitidine were irradiated with UV light in homogeneous and heterogeneous systems. Two commercial polycrystalline TiO₂ powders (Degussa P25 and Merck) were used as photocatalysts. After 5 h, an appreciable photolytic degradation of tetracycline and ranitidine was observed while the degradation of lincomycin was noticeably lower. As far as the mineralization is concerned, a small decrease of the TOC values was measured in the case of tetracycline whereas negligible variations were found for lincomycin or ranitidine. The presence of the photocatalysts greatly enhanced the degradation rates of the drugs with respect to those observed during the homogeneous experiments. The Langmuir–Hinshelwood kinetic model adequately describes the experimental results and both the pseudo-first order kinetic constants of the reactions and the adsorption constants were calculated. Merck TiO₂ was more active than P25 Degussa for the photodegradation of tetracycline and ranitidine, whereas both photocatalysts showed similar performances for lincomycin. In the presence of TiO₂ Degussa P25, tetracycline was almost completely mineralized, but the reduction of the initial TOC was ca. 60% in the case of lincomycin and ranitidine. A less significant mineralization was observed by using Merck TiO₂.     

Photocatalytic degradation of 4-nitrophenol in aqueous suspension by using polycrystalline TiO2 samples impregnated with Cu(II)-phthalocyanine

A number of supported metal oxide catalysts were screened for their catalytic performance for the oxidation of carbon black (CB; a model diesel soot) using NO₂ as the main oxidant. It was found that contact between the carbon and catalyst was a key factor in determining the rate of oxidation by NO₂. Oxides with low melting points, such as Re₂O₇, MoO₃ and V₂O₅ showed higher activities than did Fe₃O₄ and Co₃O₄. The activities of MoO₃ and V₂O₅ on various supporting materials were also examined. MoO₃/SiO₂ was the most active catalyst among the supported MoO₃ examined, whereas, V₂O₅/MCM-41 showed the highest activity among the supported V₂O₅. Different performances of the supported MoO₃ catalysts were explained by the interaction of MoO₃ with the supports: a strong MoO₃/support interaction may result in a poor mobility of MoO₃ and a poor activity for oxidation of carbon by NO₂. The high activity of V₂O₅/MCM-41 was associated with its catalysis of the oxidation of SO₂ by NO₂ to form SO₃, which substantially promotes oxidation of carbon by NO₂. Addition of transition metal oxides or sulfates to supported MoO₃ and V₂O₅ was also investigated. Combining MoO₃ or V₂O₅ with CuO on SiO₂, adding VOSO₄ to MoO₃/SiO₂ or MoO₃/Al₂O₃ and adding TiOSO₄ or CuSO₄ to V₂O₅/Al₂O₃ improved the catalytic performance.