Ileal atresia with total colonic aganglionosis

This is the 17th report of the case of an infant who had ileal atresia associated with Hirschsprung's disease, and the second with ganglion cells distal to the atresia. Experience suggests that Hirschsprung's disease should be suspected in all forms of bowel atresia.     

Can you social engineer your way into your network?

At larger customer sites, I am frequently asked to see if I can get into a computer facility or asked to gain access to corporate assets. One of the more successful manners in which to do this is via social engineering. Social engineering, is, basically, lying your way into a facility. It takes a certain amount of self-confidence and the ability to talk your way out of situations where you might get caught. It also takes a certain amount of “on your feet” thinking so that you do not get into a situation where you are discovered too soon. The idea is to test the facilities in your purview without getting caught too soon, if at all, so that improvements can be made.     

Terrace growth in partially melt-regrown EuBa2Cu3 δ high-T c superconductors

An SEM and STM study was made of terrace formation in partial melt-regrown EuBa₂Cu₃O_7?δ. Terraces form above 920°C, well below the bulk melting temperature (1075±10°C). The terrace formation is accompanied by significant grain growth, possibly triggered by a “surface-melting” transition. Melting occurs in a layer a few monolayers thick, and the highly mobile layers reconstruct into terraced form due to a faceting transition. The terrace growth can be reproduced by a theoretical faceting model. The STM also reveals a finer-scale sinusoidal modulation of the surface, of unknown origin.     

Effects of androgen deprivation on prostate alpha 1-adrenergic receptors

Twenty-four hour exposure to cycloheximide produced a concentration-dependent reduction in protein synthesis in mouse cortical cell cultures. Unexpectedly, a 24 h pretreatment with cycloheximide exposure also reduced neuronal vulnerability to subsequent oxygen-glucose deprivation-induced injury, measured both acutely (cell swelling) or after one day (cell lysis). This neuroprotective effect was attenuated if the period of cycloheximide pretreatment was shortened to 8 h, and lost if the pretreatment was shortened to 1 h. A comparable neuroprotective effect was also induced by 24 h pretreatment with another protein synthesis inhibitor, emetine. The neuroprotection induced by pretreatment with cycloheximide or emetine was probably not attributable to reduction of apoptosis: (i) neuronal death under these conditions occurs by N-methyl-D-aspartate receptor-mediated excitotoxic necrosis, not apoptosis; (ii) the same cycloheximide pretreatment did not block staurosporine-induced apoptosis. Also unlikely as an explanation is reduction in postsynaptic vulnerability to excitotoxicity, as death induced by exogenous addition of N-methyl-D-aspartate, kainate, or alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate was little affected by cycloheximide pretreatment. Rather, the protective effect of cycloheximide pretreatment was probably explained, at least in part, by marked reduction in the glutamate release induced by oxygen-glucose deprivation.     

The structure and properties of spray formed cold rolling mill work roll steels

A study of the effect of spray casting on the microstructure and properties of cold rolling mill work roll steels has been undertaken. Industry standard qualities have been spray formed and a comparison of the resulting properties and microstructures has been made with those of the conventionally processed counterparts. The influence of process variables on the spray formed product has also been investigated. The results indicate that cold mill work roll steels which have comparable properties and structures to conventionally cast and forged products can be produced successfully in a single processing step. Furthermore, a high integrity metallurgical bond between the deposit and the substrate can be achieved.     

Parametric image reconstruction using spectral analysis of PET projection data

Spectral analysis is a general modelling approach that enables calculation of parametric images from reconstructed tracer kinetic data independent of an assumed compartmental structure. We investigated the validity of applying spectral analysis directly to projection data motivated by the advantages that: (i) the number of reconstructions is reduced by an order of magnitude and (ii) iterative reconstruction becomes practical which may improve signal-to-noise ratio (SNR). A dynamic software phantom with typical 2-[11C]thymidine kinetics was used to compare projection-based and image-based methods and to assess bias-variance trade-offs using iterative expectation maximization (EM) reconstruction. We found that the two approaches are not exactly equivalent due to properties of the non-negative least-squares algorithm. However, the differences are small (< 5%) and mainly affect parameters related to early and late time points on the impulse response function (K1 and, to a lesser extent, VD). The optimal number of EM iteration was 15-30 with up to a two-fold improvement in SNR over filtered back projection. We conclude that projection-based spectral analysis with EM reconstruction yields accurate parametric images with high SNR and has potential application to a wide range of positron emission tomography ligands.     

q-Dependent neutron scattering: A signature of the gap anisotropy in high-T c superconductors

The influence of the superconducting gap anisotropy on the phonon dispersion is discussed for tetragonal and orthorhombic crystals. Superconducting order parameters with different types ofs-wave, as well asd- and (s+d)-wave anisotropies, are studied. We show that along specific directions of the Brillouin zone the lineshape (energy and linewidth) of phonons strongly depends on the anisotropy of the gap. In this context, we discuss recent experimental results performed on YBa₂Cu₃O₇ single crystals. The data can be well described in terms of an anisotropics-wave gap function obtained from the nontotally screened interaction of charge carriers with long-range optical phonons. The calculations suggest, furthermore, that it is generally insufficient to describe experiments that involve the anisotropy of the superconducting order parameter solely in terms of its symmetry. Not only the symmetry, but also the specific structure of the gap as a function of k is important. This conclusion holds for those experiments that are not restricted to the pure determination of the phase of the gap.     

Neutron irradiation-induced voids in β-silicon carbide

Pyrolytic β-silicon carbide was irradiated at temperatures between 625°C and 1500°C to neutron fluences up to 12 × 10²¹ n/cm² ($\text{E > 0.18 MeV}$). Density changes were measured and the samples were examined by transmission electron microscopy. Irradiation below 1000°C created small Frank dislocation loops on {111} planes. Irradiation at 1250°C and 1500°C produced tetrahedral voids which caused continuing expansion of the samples. Void sizes increased with increasing fluence and with increasing irradiation temperature, while void concentrations decreased with increasing temperature. One-hour post-irradiation anneals at 1700°C to 2100°C reduced the void concentration and total void volume while increasing the maximum void size.     

四种天然彩色棉的质量测定

近 1 5年来 ,对天然彩色棉的商业性兴趣胜于纯粹的好奇心。彩色棉产品性能尚好的验证 ,使它在环境意识之中孕育了一个有地位的市场。环境意识要求减少合成的化学制品如染料的使用 ,该要求刺激了彩色棉培育的努力 ,彩色棉培育不但要增加色谱范围 ,而且要提高纤维质量。培育者惊奇地发现许多彩色棉栽培变种特别耐寒 ,有惊人的抗病、抗旱、抗病害能力。可惜的是 ,相对于白色棉 ,彩色棉常较弱且较短。培育计划中 ,生产的棉花量只是几株植物的产量 ,这些数量只能用 70多年前生产的称为小型纺纱机械纺纱进行评估。这些机械没有现代工业生产设备那…