Transimpedance amplifier with 120 dB dynamic range

A transimpedance amplifier (TIA) with compression of the input current is presented. The proposed TIA has two regions of operation: a linear one for small input currents and one with compression for high currents, which would otherwise saturate the TIA. The measured -3 dB bandwidth is 102 MHz, the equivalent RMS input current noise is 20.2 nA and the maximal current overdrive is 20.5 mA, leading to a dynamic range at the input of 120 dB     

A combination of a common splice site mutation and a frameshift mutation in the COL7A1 gene: absence of functional collagen VII in keratinocytes and skin

Musk xylene (2,4,6-trinitro-1-t-butylxylene; MX) is a synthetic nitromusk perfume ingredient that induces and inhibits mouse cytochrome P4502B (CYP2B) enzymes in vivo. The purpose of the present work was to determine whether amine metabolites of MX contributed to the enzyme inhibition and, if so, to define the nature and kinetics of this inhibition. When dosed orally to phenobarbital (PB)-treated mice, MX (200 mg/kg) inhibited > 90% of the PB-induced O-dealkylation of 7-pentoxyresorufin (PROD), and [14C]MX equivalents bound covalently to microsomal proteins. However, when this experiment was repeated in mice pretreated with antibiotics to eliminate the gastrointestinal flora, no decrease in PB-induced PROD activity and no covalent binding to microsomal proteins were observed. Thus, the ability of antibiotic treatment to eliminate the enzyme inhibition and covalent binding implicated amine metabolites of MX formed by nitroreduction in anaerobic intestinal flora as obligatory for these effects. Two monoamine metabolites of MX were synthesized to study enzyme inhibition directly. These metabolites were 2-amino-4,6-dinitro-1-t-butyl-xylene and 4-amino-2,6-dinitro-1-t-butylxylene, referred to as o-NH2-MX and p-NH2-MX, respectively, reflecting the position of the amine substitution relative to the t-butyl function. In the in vitro studies with PB-induced mouse liver microsomes, both amines inhibited PROD activity when preincubated in the absence of NADPH. However, only p-NH2-MX caused a time- and NADPH-dependent loss of PROD activity, and the inactivation rate was a pseudo-first-order process that displayed saturation kinetics. These results indicate that p-NH2-MX is a mechanism-based inactivator of mouse CYP2B enzymes. From kinetic analyses, the Ki was calculated to be 10.5 microM and the Kinact was 1.2 min-1. As final confirmation of the inhibitory effects of p-NH2-MX on mouse CYP2B enzymes, the amine (0.67 mmol/kg) was dosed orally to PB-induced mice. At 2 hr after dosing, p-NH2-MX inhibited essentially all of the PB-induced PROD activity, whereas an equimolar dosage of parent MX had no effect at this early time. Thus, although MX is an inducer of mouse CYP2B enzymes, an amine metabolite of MX is a mechanism-based inactivator of mouse CYP2B10. Furthermore, it is likely that the amine is responsible for the lack of functional CYP2B enzyme activity associated with induction of this enzyme by MX.     

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Directional solidification of dendritic microstructures in microgravity and with forced melt flow

A dendritic microstructure is characteristic for many metallic alloys used in practical application. Mainly the heat and mass transport in the melt in front of the growing solid-liquid interface affects the microstructure. Purely diffusive transport conditions as realized in microgravity environment produce larger primary spacing than found in earth-grown samples. Forced melt flow generated by a rotating magnetic field results in shorter primary spacing and a significant change of the dendrites’ shapes.     

Computing the algebraic relations of C-finite sequences and multisequences

We present an algorithm for computing generators for the ideal of algebraic relations among sequences which are given by homogeneous linear recurrence equations with constant coefficients. Knowing these generators makes it possible to use Gröbner basis methods for carrying out certain basic operations in the ring of such sequences effectively. In particular, one can answer the question whether a given sequence can be represented in terms of other given sequences.     

Autonomic and Decentralized Management of Wireless Access Networks

In this article, we apply autonomic and distributed management principles to wireless access networks. Most interesting is the application of autonomic properties and behaviors including adaptive, aware, and automatic operation in a decentralized setting. In particular, we present a generic and autonomic management architecture for decentralized management of wireless access networks, such as GERAN/UTRAN, E-UTRAN, WiMAX or WLAN. For evaluation purposes, we apply this architecture to the management of a Wireless LAN network, and we evaluate the architecture and some of the autonomic management functions through simulations, a prototype implementation and the setup of a real-world testbed for experimentation with the proposed management approach.     

A 5-Gb/s OEIC with voltage-up-converter

In this paper (based on our previous paper at ESSCIRC 2004, "A 2.4 GHz-Bandwidth OEIC with Voltage-Up-Converter," but new results for 4 Gb/s and 5 Gb/s have been added), an optoelectronic integrated circuit (OEIC) with an integrated voltage-up-converter (VUC) to enhance the frequency response of an integrated pin photodiode is presented. With the VUC a voltage of 11 V is generated on the chip without any additional external components. Thus, for a single-supply environment of 5 V the bandwidth of the OEIC is increased from 1.5 to 2.4 GHz. For data rates of 1, 3, 4, and 5 Gb/s at a bit error rate of 10/sup -9/, sensitivities of -29.3, -24.3, -22.9, and -20.5 dBm, respectively, were measured at a wavelength of 660 nm. For the implementation of the OEIC a modified 0.6-/spl mu/m silicon BiCMOS technology with f/sub T/=25 GHz is used.