The phenotype of chromosome 2p-linked limb-girdle muscular dystrophy

This study reports on a detailed clinical, electrophysiological, muscle computed tomography (CT) and laboratory investigation carried out on five families with definite linkage to chromosome 2p. Some clinical and laboratory features were common to most of the patients, such as the very high serum creatine kinase (CK) levels (mean 43.70 times the normal). The onset was most frequently in the late teens or early twenties with weakness and wasting of the pelvic girdle muscles. All patients had normal motor milestones and had not complained of any symptoms of muscle disease in early childhood. The clinical course was variable both between and within some families, but was most often slowly progressive. Some variability in the pattern of muscle involvement between the different families has also been observed.     

A gene for autosomal recessive limb-girdle muscular dystrophy maps to chromosome 2p

The limb-girdle muscular dystrophies are a clinically and genetically heterogeneous group of disorders. We have studied two large inbred families of different ethnic origin and excluded linkage to LGMD2 on chromosome 15q and SCARMD on chromosome 13. Proceeding to a genomic linkage search, we have now identified linkage to markers D2S134 and D2S136 on chromosome 2p (maximum lod score 3.57 at zero recombination). The phenotype in the two families was similar, with onset in the pelvic girdle musculature in the late teens and usually relatively slow progression. This work identifies a second locus for autosomal recessive limb-girdle muscular dystrophy.     

Elimination of the sidewall defects in selective epitaxial growth(SEG) of silicon for a dielectric isolation technology

Selective epitaxial growth (SEG) of silicon has not had widespread use as a dielectric isolation technology due to the near sidewall defects at the SiO₂/Si interface. These defects are located in the first 1-2 μm of the SEG/sidewall SiO₂ interface. Diode junctions intersecting the sidewall and 5 μm removed from the sidewall were fabricated in SEG material using thermally grown silicon dioxide (OX) and thermally nitrided thermal silicon dioxide (NOX) as the field insulating mask. Averaged over 16 devices of each type, diodes fabricated with NOX had much better low current I-V characteristics and minimum ideality factors (1.03) than diodes fabricated with OX field oxides (1.23). Junctions intersecting the NOX field insulator had nearly identical characteristics to bulk SEG     

Thermal diffusivity of liquids determined by flash heating of a three-layered cell

An investigation of the applicability of the flash heating of a three-layered cell for determining the thermal diffusivity of a central liquid layer at temperatures between its melting and boiling points is described. Two different cell designs were developed. In one, the outside layers were brazed to a ring-shaped central spacer; in the other, bolted flanges held the outside layers against a central spacer. Test units were fabricated from type 304 stainless steel. Thermal diffusivity results for water obtained with two brazed cells and one bolted cell were all within ±1% of standard reference values. Results obtained with a high temperature salt (Hitec) with two brazed cells were within ±2.5% of each other over the temperature range of 149–427°C. In contrast, bolted cell measurements were inconsistent.     

The Management and Processing of Network Performance Information

The performance of communications networks can be monitored intrusively by transmitting test packets on the network links being tested. The delays experienced by these test packets and the number of test packets lost or duplicated may provide an indication of the performance of the links being monitored. Intrusive network monitoring, even at modest sampling rates, generates a significantly large amount of primitive data. This data needs to be summarised appropriately to address the required network performance analysis operations. These operations are generally iterative in nature, where the results of initial processing and analysis generate requirements for further processing and analysis. This paper describes the architecture of a database that can assist in efficient analysis of network performance by reusing the information derived at various stages.     

A simple process to produce a high quality silicon surface prior toselective epitaxial growth

A simple and low-cost process was devised to eliminate etch damage resulting from oxide etching on the seed-hole surface prior to selective epitaxial growth (SEG) of silicon. The process consists of a low power C ₂F₆ RIE step which was performed right after the oxide etch step in the same etch reactor. The use of this step excluded the need of a conventional sacrificial oxide to remove damaged silicon regions and residual polymers. The n-p diodes resulting from n-type SEG grown on p-type substrate were used to evaluate the quality of the silicon surface prior to SEG     

Gravity and configurational energy induced microstructural changes in liquid phase sintering

Liquid phase sintered materials consist of interconnected crystalline grains in a homogeneous matrix phase that forms the liquid at high temperatures. The dihedral angle, grain size, and volume fraction of solid determine the energy of the system. Energy minimization is possible by the separation of phases due to density differences. This explains why some materials exhibit settling or distortion due to gravity during liquid phase sintering. Experiments performed with W-Ni-Fe heavy alloys are used to measure the microstructural changesvs position that occur in liquid phase sintering under normal gravity. The experimentally observed segregation is less than the calculated equilibrium seg-regation due to the retarding effect from the rigid solid skeleton formed during sintering. These re-sults improve our understanding of microstructure, mechanical properties, component shape, and dimensional stability benefits that may be realized from low gravity sintering. This paper is based on a presentation made in the symposium “Experimental Methods for Microgravity Materials Science Research” presented at the 1988 TMS-AIME Annual Meeting in Phoenix, Arizona, January 25-29, 1988, under the auspices of the ASM/MSD Thermo-dynamic Data Committee and the Material Processing Committee.     

Low cycle fatigue of as-HIP and HIP+forged rené 95

The continuous cycling and hold time low cycle fatigue properties of the Ni base superalloy René 95 were studied at 649°C using powder products (−60 mesh) in the as-HIP and HIP + forged conditions. It was shown that cracks were initiated by pores, by ceramic particles and by a classical stage I mechanism for both materials and for both cycle characters. For the continuously cycled as-HIP material, deformation was restricted to well defined bands at low strains and became homogeneous as the strain level increased. The total energy to fracture increased abruptly in the low strain regime and this was also reflected by a break in the Coffin-Manson plot. In all cases cracks initiated at pores. The hold time specimens exhibited an extremely high dislocation density and surface connected initiation yet without a significant life reduction. The observations were essentially similar for the HIP + forged material except that deformation tended to be confined to well defined slip bands even at high strains and to some extent even for the hold time tests. This behavior was attributed to the fact that theγ′ were smaller, more coherent and more readily sheared by dislocations which were strongly paired. There was a marked tendency for crack propagation to change from transgranular to intergranular (also observed for the as-HIP material) at a unique combination of crack length and plastic strain. The transition occurred at shorter crack lengths for the HIP + forged material except when crack initiation was subsurface. In this case the transition was delayed and the life was greatly enhanced, indicating that the environment plays a major role in determining the fatigue life. PHILIPPE TAUPIN formerly Research Associate, Department of Materials Science, University of Cincinnati.     

Comparative response of mixed cultures of bacteria and virus to ozonation

The ozone disinfection studies were performed using five cultures of organisms: i.e. a yeast Candida parapsilosis. an acid-fast organism Mycobacterium fortuitum, Salmonella typhimurium, Escherichia coli and poliovirus to determine their relative resistance to ozone in a given completely mixed continuous flow system. Studies were conducted in both clean aqueous system and secondary wastewater effluent. Their resistance to ozone in both cases was observed in the following order: M. fortuitum > poliovirus type 1 Mahoney strain >C. parapsilosis > E. coli > S. typhinturium.     

Rare causes of occult small intestinal bleeding, including aortoenteric fistulas, small bowel tumors, and small bowel ulcers

The most common cause for gastrointestinal bleeding of small bowel origin is angiodysplasia, followed by tumors of the small intestine, and various other causes, including small bowel ulcers and aortienteric fistulas. With the advent of improved diagnostic tests, including push and sonde enteroscopy, timely endoscopic diagnosis of these rare small bowel lesions has become possible, enabling the clinician to make better therapeutic decisions. This article focuses on the rare small bowel sources of intermittent and chronic gastrointestinal blood loss.