Is it possible to differentiate between choledochal cyst and congenital biliary atresia (type I cyst) by antenatal ultrasonography?

Both choledochal cyst and congenital biliary atresia (type I cyst) may share the same ultrasonographic pattern. We report 2 cases which were shown to have cystic structures on the upper abdomen by antenatal ultrasonography. The size of the choledochal cyst found at 24 weeks' gestation increased steadily as gestational age advanced. But the size of the cyst in congenital biliary atresia found at 29 weeks' gestation remained unchanged throughout the remaining pregnancy. Cyst enlargement, therefore, may suggest the possibility of a choledochal cyst.     

On stability of an input amplitude constrained predictive control system

This paper presents stability results for discrete-time model-based predictive control system subject to an input amplitude constraint. It is shown that the input amplitude constrained control system may provide a stable control system in the sense of BIBO when the system to be controlled is of a class of the system poles which consist of multiple integrators and a stable polynomial. The solution of Diophantine equations and their properties are addressed. Simulation study is also carried out and it is shown that the output of the system may converge to the reference signal for certain degree of constraints.     

Growth rate and surface microstructure in α(6H)–SiC thin films grown by chemical vapor deposition

Monocrystalline 6H-SiC thin films have been epitaxially grown on off-axis 6H-SiC {0001} substrates in the temperature range of 1623–1873 K via chemical vapor deposition. The growth rate was a strong function of the growth temperature and the reactant gas concentration. The activation energies for growth were 64 kJ/mole and 55 kJ/mole for the (0001) Si face and the (0001) C face, respectively. The concentration of growth pits in the films increased as a function of decreasing deposition temperature, increasing concentration of reactant gases and increasing off-axis orientation. Beta-SiC islands were also observed in the epilayers when the (SiH₄ + C₂H₄)/H₂ ratio was ≥2.5:3000.     

Two-level optimal output feedback stabilizer design

The paper addresses the design of two-level power system stabilizers using an optimal reduced order model whose state variables are torque angles and speeds. The reduced order model retains their physical meaning and is used to design a two-level linear feedback controller that takes into account the realities and constraints of electrical power systems. The two-level control strategy is used, and a global control signal is generated from the output variables to minimize the effect of interactions. The effectiveness of this controller is evaluated and a multimachine system is given as an example to illustrate the advantages of the proposed method. Responses of the system with a two-level scheme and an optimal reduced order scheme are included for comparative analysis.     

Differential effects of aging on directional and absolute errors in visuospatial memory.

Studied memory for visuospatial arrays in 28 male and 34 female healthy dextral adults (aged 20–90 yrs). 10 abstract figures were presented in each hemispace over a series of learning trials, and then delayed free recall of figure placement was obtained. Figures were misplaced significantly downward and leftward in both hemispaces. Both vertical and horizontal absolute error increased significanty with age, but no age effects on directional errors were observed. The increase in absolute error over age is consistent with decreased anterograde memory and visuospatial skills in the elderly. The directional errors are believed to result from an attentional shift toward proximal peripersonal space, in combination with attentional shifts from differential left vs right cerebral activation. Gender effects were also observed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cure reaction for modified diallylbisphenol A/diaminodiphenylsulfone/bismaleimide

The glass‐transition temperature as a function of curing conversion for a modified diallylbisphenol A/diaminodiphenylsulfone/bismaleimide (BMI) resin was investigated at different temperature regimes and modeled using a modified Di Benedetto equation. Although the relationship between the glass‐transition temperature and conversion of the BMI system conforms to the Di Benedetto equation for α < 0.6 and at lower cure temperatures, at higher cure temperatures the results deviated significantly from the equation; thus, it was an inadequate model for the system. Fourier transform IR analysis showed that the major crosslinking reactions did not occur during cure for the modified BMI at and below 150°C. However, as the cure temperature was increased, the crosslinking reactions responsible for 3‐dimensional network structures became more dominant. At 190°C the C? N? C_stretch vibration of the uncured maleimide ring converted into succinimide rings in the curing process. Simultaneously, a decrease was observed for the absorbance bands of ? C? H_bending (maleimide). The higher cure temperatures induced a significantly faster initial crosslinking rate and also resulted in a shorter period of time after which further crosslinking was retarded, because the increase in the crosslinks also physically slowed further crosslinking activity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 227–235, 2002     

Anabaena sp. strain PCC 7120 responds to nitrogen deprivation with a cascade-like sequence of transcriptional activations

Anabaena sp. strain PCC 7120 adapts to deprivation of fixed nitrogen by undergoing physiological and genetic changes that include formation of N2-fixing heterocysts. Whether or not certain of the genes involved are interdependently expressed has been studied.     

Xefiltin, a Xenopus laevis neuronal intermediate filament protein, is expressed in actively growing optic axons during development and regeneration

Neurofilaments are an important structural component of the axonal cytoskeleton and are made of neuronal intermediate filament (nIF) proteins. During axonal development, neurofilaments undergo progressive changes in molecular composition. In mammals, for example, highly phosphorylated forms of the middle- and high-molecular-weight neurofilament proteins (NF-M and NF-H, respectively) are characteristic of mature axons, whereas nIF proteins such as alpha-internexin are typical of young axons. Such changes have been proposed to help growing axons accommodate varying demands for plasticity and stability by modulating the structure of the axonal cytoskeleton. Xefiltin is a recently discovered nIF protein of the frog Xenopus laevis, whose nervous system has a large capacity for regeneration and plasticity. By amino acid identity, xefiltin is closely related to two other nIF proteins, alpha-internexin and gefiltin. alpha-Internexin is found principally in embryonic axons of the mammalian brain, and gefiltin is expressed primarily in goldfish retinal ganglion cells and has been associated with the ability of the goldfish optic nerve to regenerate. Like gefiltin in goldfish, xefiltin in Xenopus is the most abundantly expressed nIF protein of mature retinal ganglion cells. In the present study, we used immunocytochemistry to study the distribution of xefiltin during optic nerve development and regeneration. During development, xefiltin was found in optic axons at stage 35/36, before they reach the tectum at stage 37/38. Similarly, after an orbital crush injury, xefiltin first reemerged in optic axons after the front of regeneration reached the optic chiasm, but before it reached the tectum. Thus, during both development and regeneration, xefiltin was present within actively growing optic axons. In addition, aberrantly projecting retinoretinal axons expressed less xefiltin than those entering the optic tract, suggesting that xefiltin expression is influenced by interactions between regenerating axons and cells encountered along the visual pathway. These results support the idea that changes in xefiltin expression, along with those of other nIF proteins, modulate the structure and stability of actively growing optic axons and that this stability is under the control of the pathway which growing axons follow.