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The existing techniques available for the statistical estimation of the dc input signal stability in general-order Σ-Δ analog-to-digital (A/D) converters are based on the assumption that the constituent quantizer input signal has a Gaussian distribution. However, empirical investigations reveal that this assumption holds adequately true only for the special case of conventional first-order Σ-Δ A/D converters. This paper presents an alternative technique for the accurate estimation of the dc input signal stability for higher-order Σ-Δ A/D converters. This estimation technique is based on the practical assumption that the constituent quantizer operates in its overload-free region, permitting the characterization of the quantizer output signal digit-pattern for the determination of the statistical moments of the corresponding quantizer input signal. The resulting statistical moments are subsequently incorporated in a Gram-Charlier series for an accurate quasi-linear modeling of the quantizer. A typical application example is given to demonstrate the accuracy of the proposed statistical technique for predicting the existence of multiple regions of instability and stability in the Σ-Δ A/D converter operation, and particularly for predicting the point where the A/D converter operation becomes unstable. [ABSTRACT FROM AUTHOR]

Reports the cloning of a complementary DNA encoding a subtype of the gamma-aminobutyric acid B (GABAB) receptor (GABABR2), which was identified by mining expressed-sequence-tag databases. The indication that, in vivo, functional brain GABAB receptors may be heterodimers composed of GABABR1 and GABABR2; GABA being the main inhibitory neurotransmitter in the mammalian central nervous system.

Presents research which showed the functions of the calcitonin-receptor-like receptor (CRLR). CRLR a receptor for calcitonin-gene-related peptide (CGRP) or the adrenomedullin peptide; Determination of which peptide CRLR acts as a receptor for; Importance of receptor-activity-modifying proteins (RAMPs); Roles for RAMP1 and RAMP2.

Congenital stationary night blindness is characterized by disturbed or absent night vision that is always present at or shortly after birth and nonprogressive. The X-linked form of the disease (CSNBX; McKusick catalog no. 31050) differs from the autosomal types in that the former is frequently associated with myopia. X-chromosome-specific polymorphic DNA markers were used to carry out linkage analysis in three European families segregating for CSNBX. Close linkage without recombination was found between the disease locus and the anonymous locus DXS7, mapped to Xp11.3, assigning the mutation to the proximal short arm of the X chromosome. Linkage data obtained with markers flanking DXS7 provided further support for this localization of the gene locus. Thus, in addition to retinitis pigmentosa and Norrie disease, CSNBX represents the third well-known hereditary eye disease the locus of which is mapped on the proximal Xp and closely linked to DXS7. [ABSTRACT FROM AUTHOR]

A hypervariable DNA marker is closely linked to one of the most severe forms of night blindness, X-linked retinitis pigmentosa (RP). Affected individuals with X-linked RP, obligate carriers, and ophthalmologically identifiable carriers of the disease were included in a linkage study. The diagnosis was established in five sibships by funduscopic and electrophysiological investigations. When the X-linked probe M27β was used, 2 recombinants out of 29 informative meioses were detected (θ=0.07 at a maximum lod of 4.75). The hypervariable probe detected two different alleles in 38 of 39 females tested. M27β is therefore a potentially very useful probe for carrier detection and prenatal diagnosis, as well as for addressing the question of heterogeneity of X-linked RP. [ABSTRACT FROM AUTHOR]