Molecular analysis of cellulose biosynthesis in Arabidopsis

Cellulose, an abundant, crystalline polysaccharide, is central to plant morphogenesis and to many industries. Chemical and ultrastructural analyses together with map-based cloning indicate that the RSW1 locus of Arabidopsis encodes the catalytic subunit of cellulose synthase. The cloned gene complements the rsw1 mutant whose temperature-sensitive allele is changed in one amino acid. The mutant allele causes a specific reduction in cellulose synthesis, accumulation of noncrystalline beta-1,4-glucan, disassembly of cellulose synthase, and widespread morphological abnormalities. Microfibril crystallization may require proper assembly of the RSW1 gene product into synthase complexes whereas glucan biosynthesis per se does not.     

A noise resistant synchronization scheme for HDTV images

A method that increases the error resistance of the HDTV system and offers graceful picture degradation in the presence of bit errors, is presented. Due to the nature of the presently proposed compression schemes for HDTV systems, an error in a data bit does not only affect the block the bit belongs to, but unfortunately the effects of this error may perpetuate to the following blocks. This is because a bit error may cause loss of synchronization between the data bits and the picture blocks they represent. Our method restricts the effects of a bit error to a picture block whose size is significantly smaller than those used by the HDTV systems. We achieve synchronization by transmitting a header-word for each such synchronization block. Each header-word contains the number of data bits representing the compressed block. This header-word is protected by two levels of FEC code. To decrease the number of extra bits needed by the header-words, two different synchronization block sizes are used, a relatively small block size for the reference frames and a larger size for the inter-frames. The resulting method improves the quality of the picture in the presence of errors and defers the SNR at which the HDTV picture suddenly deteriorates by 2.5 to 3 dB. It also allows operation at higher order modulation transmission schemes, e.g., 32-QAM instead of 16-QAM, without the requirement of increased signal power     

Regulation of the raffinose permease of Escherichia coli by the glucose-specific enzyme IIA of the phosphoenolpyruvate:sugar phosphotransferase system

In enteric bacteria, chromosomally encoded permeases specific for lactose, maltose, and melibiose are allosterically regulated by the glucose-specific enzyme IIA of the phosphotransferase system. We here demonstrate that the plasmid-encoded raffinose permease of enteric bacteria is similarly subject to this type of inhibition.     

Effect of not breastfeeding on the risk of diarrheal and respiratory mortality in children under 2 years of age in Metro Cebu, The Philippines

The effects of not breastfeeding on mortality due to diarrhea and acute lower respiratory infection (ALRI) in children under 2 years of age were examined using data from a 1988-1991 longitudinal study of 9,942 children in Metro Cebu, The Philippines. Cox regression methods were used to study the magnitude of the risks, possible interactions with birth weight and nutritional status, and the effect of additional confounding factors. Not breastfeeding had a greater effect on diarrheal mortality than on ALRI mortality. In the first 6 months of life, failing to initiate breastfeeding or ceasing to breastfeed resulted in an 8- to 10-fold increase in the rate of diarrheal mortality. The rate of mortality associated with both ALRI and diarrhea was increased nearly six times by not breastfeeding, but the rate of ALRI mortality alone was not increased. The data also suggested that the risk of mortality associated with not breastfeeding was greater for low birth weight infants and infants whose mothers had little formal education. After age 6 months, the protective effects of breastfeeding dropped dramatically. These findings underscore the importance of promoting breastfeeding, especially during the first 6 months of life, and of targeting high risk groups such as low birth weight babies and those of low socioeconomic status.     

Fine needle aspiration cytodiagnosis of subcutaneous fat necrosis of newborn. A case report

We recently diagnosed subcutaneous fat necrosis in a newborn female infant using fine needle aspiration cytology. The neonate had perinatal asphyxia and her mother a difficult labor, but otherwise the neonate was well developed and healthy and within a few days developed well-defined areas of subcutaneous induration all over. On cytologic examination of the aspirated material, many necrotizing fat cells were found with refractile, needle-shaped crystals arranged in a sheaflike or starburst pattern. Subcutaneous fat necrosis of the newborn is uncommon today, and although the histologic findings from excised tissue are known, this appears to be the first case in which the diagnosis was possible from a sample of fine needle aspirate.     

A Method for Measuring Pulsed Amplifier Noise Using a Spectrum Analyzer

Measuring the noise generated by a pulsed RF amplifier is not a simple task [1]. One method of making this measurement converts the RF pulse to video with a phase detector and uses a spectrum analyzer to measure the noise between the lines of the pulse spectrum. The measurement includes the combined effects of timing jitter, power-supply modulation, and amplifier noise. An alternate method, described in this note, requires less test equipment by using an RF spectrum analyzer to measure the noise at a point outside the pulse spectrum. This measurement responds only to amplifier noise and is valid if the noise density is the same both inside and outside the pulse spectrum. Since this situation tends to be true of broad-band amplifiers such as TWT's and CFA's, the second method is preferable because of its relative simplicity. This note describes the procedure for measuring pulsed amplifier noise using an RF spectrum analyzer. The test setup and measurement procedure are described, as well as the conversion of the measured spectral-density ratio to an equivalent CW signal-to-noise ratio.     

Type A behavior, achievement striving, and a dysfunctional self-evaluation system.

We conducted two experiments to examine the relations among characteristics of how Type A individuals strive for achievement, including goal achievement, self-evaluation, and psychological distress. We evaluated these relations as subjects performed two sequential general information tests. Experiment 1 indicated that achievement striving associated with the Type A behavior pattern is characterized by a tendency to set personal goals in excess of performance and is associated with a low probability of achieving goals. The results of Experiment 2 indicated that the achievement strategy Type A individuals adopted was associated with low self-evaluation of their actual performance. Furthermore, a pre- and postexperiment self-report questionnaire of psychological state suggested that failure to achieve personal goals was related to increased psychological distress. The results of our study suggest that unrealistically high performance standards and failure to achieve personal goals may be a mechanism that triggers the negative psychological states and performance dissatisfaction associated with the Type A behavior pattern. Our study also supports theoretical conceptualizations that excessive achievement striving can act as a potential motivational mechanism. (PsycINFO Database Record (c) 2010 APA, all rights reserved)