Contextual conditioning and auditory cue conditioning dissociate during development.

Following a single shock presentation, fear conditioning to an auditory cue and to the experimental context was assessed by measuring the rat's tendency to freeze. On the conditioning day, 18-day-old rats showed as much freezing to the auditory cue as older rats. However, 18-day-old pups displayed much less freezing to the training context than did pups 21–27 days old. The developmental dissociation between contextual and auditory cue conditioning parallels the dissociation produced by damage to the adult rat's hippocampal system (J. J. Kim and M. S. Fanselow, 1992; R. G. Phillips and G. E. LeDoux, 1992). The dissociation is also consistent with the developmental hypothesis that the configural association system develops late in comparison with the elemental association system (J. W. Rudy, 1991, 1992). The implications of the findings for the maturation of the neural components of the fear-conditioning circuit also are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

1-Hydroxypyrene levels in coal-handling workers at a coke oven

An environmental and medical survey was conducted at the coal-handling area of a coke oven, where workers came in contact with coal-tar sludge. The purpose of the study was to determine if skin contact with coal-tar sludge was an important route of exposure to pyrene because workers were observed to have substantial contact with the sludge. Environmental monitoring revealed minimal airborne exposure to pyrene, a byproduct of the coke distillation process; only one personal breathing zone sample detected pyrene, and at least of 0.001 mg/m3. However, the mean preshift urinary 1-hydroxypyrene concentration was 1.00 mumol/mol creatinine (range, 0.16 to 2.96 mumol/mol creatinine) and the mean postshift level was 1.7 mumol/mol creatinine (range, 0.24 to 4.85 mumol/mol creatinine) (P < 0.01). These levels probably reflect absorption as a result of skin exposure.     

Medical imaging research on idiopathic hemifacial spasm

In order to have a medical imaging examination for idiopathic hemifacial spasm before surgery, we designed a new method by using vertebroarterial DSA and vertebroarterial CTA based on an aired cisternapontis, 36 patients were examined since 1989 and the compression of the facial nerve from brain stem to porus acousticus internus was showed clearly in all the cases. The arteries responsible for the compression were cerebellar inferior posterior (55.6%), cerebellar inferior anterior (44.4%), auditory internus (25.0%) and vertebroarterial (11.1%), 36% of all the cases had more than one responsible arteries, 22.2% cases had only one compression point, 38.9% had two points, 25.0% had 3 and 13.9% had more. 85.7% of the compression points located in the root zone and 14.3% near the porus acousticus internus. 24 cases were treated with decompression surgery, it indicated that the compression conditions just met the medical imaging examinationg results. After surgery the symptom disappeared in 23 cases and remarkably released in one case with no death case. We believed that this method might be helpful to idiopathic hemifacial spasm decompression surgery and other surgeries in the CP angle.     

Taking the challenge of multiple access for third-generationcellular mobile radio systems-a European view

In Europe, the challenge of the design of third-generation cellular mobile radio systems has been taken numerous research and development activities in this field have been started. The authors try to give an overview of the European activities in this field. The article is organized in two parts. In the first part, the requirements for third-generation cellular mobile radio systems such as Universal Mobile Telecommunications System (UMTS) and Future Public Land Mobile Telecommunications System (FPLMTS), which has been named International Mobile Telecommunications after the year 2000 (IMT-2000) are presented concisely. Also, the importance and challenge of the multiple access design for such third-generation cellular mobile radio systems is explained. In the second part, numerous European research activities with focus on the multiple access design for third-generation cellular mobile radio systems are reviewed     

Radar cross section measurements using near-field radar imaging

In this paper a technique to obtain the far-field scattering signature of bodies, using near-field measurements, is proposed. The method is based on near-field radar imaging techniques. The backscattered field data are collected in a controlled environment over a large frequency band and aspect angle using a near-field antenna. A focused radar image of the body is generated. Probe correction to compensate for the radiation pattern of the interrogating antenna is conducted during the two-dimensional imaging of the object. The contribution from each scattering center to the total backscattered far-field is obtained from the radar image. The proposed technique is applied to obtain the far-field radar cross section (RCS) for an object from near-field measurements conducted in an anechoic chamber at the University of Pretoria, South Africa     

Cure Levels, Processing Methods and Meat Source Effects on Low-fat Frankfurters

Frankfurters were manufactured from lean meats (100% beef and 50:50 beef-pork) to contain reduced levels of fat (about 1.3%). A curing solutibn was added to yield 160% of fresh meat weight. Three processing methods, coarse ground tumbled, fine ground tumbled and fine ground emulsified were used. All products were cooked in live steam to 71°C internal temperature. Product yields, penetrometer values, color, chemical composition, caloric content and added water were evaluated. Emulsified frankfurters from 50:50 beef-pork mixtures at 160% cure had texture similar to conventional product as well as increased (P<0.05) yields, acceptable color and 74% fewer calories.     

Characterization of solid-phase welds between Ti---6A1---2Sn---4Zr---2Mo---0.1Si and Ti---13.5A1---21.5Nb titanium aluminide

Dissimilar-alloy welds have been produced between Ti---6Al---2Sn---Z4---2Mo---0.1Si (wt. %) and Ti---13.5Al---21.5 NB (wt.%) titanium aluminde using the three different solid-phase welding processes that create significantly different thermo-mechanical conditions at the weld interface. Exposure to supertransus temperatures, appreciable deformation and rapid cooling of the weld interface region during linear-friction welding promote dynamic recrystallization of beta grains and beta decomposition to fine martensitic products. In contrast, diffusion welding at temperatures below the base metal beta transus temperatures and at relatively low pressures minimizes deformation and microstructural variations in the weld interface region relative to the unaffected base metal. During capacitor-discharge resistance spot welding, extremely rapid heating of the weld interface region to near-solidus temperatures, and subsequent rapid cooling, result in the formation of a metastable, ordered-beta microstructure in the Ti---s13.5Al---21.6Nb and fine alpha-prime martensite in the Ti---6Al---2Sn---4Zr---2Mo-0.1Si.     

Early detection of ageing in solder joints through laser probe thermal analysis of the peltier effect

We have recently developed an optical contactless method for testing the quality of solder joints during accelerated thermal cycling ageing processes.¹ The method was based upon the measurement of the dynamic thermal behaviour of the joint to short bursts of Joule heating. It has proved to be efficient in revealing the formation of cracks at the lead-solder interface. We present a method to evaluate ageing at a much earlier stage in the cycling process. We have observed in earlier work,¹ that before cracks appear, structural changes occur in the solder at the lead-solder interface. The thermal response of the solder joint is recorded over time to a Peltier heat perturbation produced by flowing a current pulse through the interface where structural changes occur. The key point in this method is to discriminate the Peltier effect from the Joule thermal response because both effects generate heat. The variation of the early Peltier response in the thermal cycling ageing tests is seen as a quantitative signature of the structural changes in the lead-solder interface.     

Effect of air gap on cylindrical dielectric resonator antenna operating in TM/sub 01/ mode

The results of a numerical study on the effect of an air gap on the input impedance and resonance frequency of a cylindrical dielectric resonator (CDR) antenna operating in the TM/sub 01/ mode as a function of dielectric constant are presented. The CDR resides on a conducting ground plane and is excited by a coaxial probe through the bottom of the ground plane. Some of the numerical results are validated experimentally.<>