Numerical simulations demonstrate that the double tapering of the spatualae of lizards and insects maximize both detachment resistance and stability

Many biological attachment devices of insects, spiders and geckos consist of arrays of hairs (setae), which are terminated by contact elements of different shapes. However, the most frequently observed shape is a thin plate-like spatula. In spite of a rather wide range of sizes, most spatulae of different animals are not uniform, but rather possess a gradient in thickness and width. Here we show that the spatulae of insects and geckos become gradually thinner and wider approaching the end. This geometrical effect is explained in the present paper, by using a numerical approach for the modelling of the van der Waals adhesion and friction between the contact elements and the substrate. The approach suggests that the observed negative thickness gradient contributes to the improvement of the adhesion resistance, whereas the positive width gradient increases the stability of the detachment, probably a key factor in controlling the animal walking.     

Effect of lattice-mismatched growth on InAs/AlSb resonant-tunnelingdiodes

Nominally identical InAs/AlSb resonant-tunneling diodes are fabricated on InAs and GaAs substrates to ascertain the effect of dislocations on the resonant-tunneling process. Although the diode on the GaAs substrate had a much higher dislocation density, as evidenced by X-ray diffraction measurements, it displayed only a small decrease in peak-to-valley current ratio     

A cerebral blood flow study on tonic pain activation in man

The investigations of hair samples obtained from human skeleton from the Christian cemetery of Sayala demonstrate the presence of nicotine. 12 of 39 individual hair samples were positive. These results indicate the use of plants containing nicotine as principal or secondary alkaloid.     

Bilateral paramedian thalamic infarction: Neuropsychological and perfusional followup study.

Conducted a 2-yr follow-up of a woman (aged 35 yrs) who had a bilateral paramedian thalamic infarction and suffered from a sudden impairment of consciousness followed by a global deficit of cognitive functions. Two years after clinical onset, verbal and visuospatial memory, verbal fluency, constructional praxia, and categorization were mainly affected. In the acute phase, a single-photon emission-computed tomography study showed a severe and diffuse cerebral blood flow (CBF) impairment, more marked on the right side. Radioisotope uptake in frontal and temporal cortices was still reduced 2 yrs later. The CBF depression in these regions suggests that the decline of cognitive functions could be due to an interruption of thalamocortical projections. A degenerative process rather than a "diaschisis" could be responsible for the long-lasting deficit of cognitive functions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Glass Surface Layer Density by Neutron Depth Profiling

Several lithium-disilicate ( Li₂O∙2SiO₂ ) glass samples were synthesized, polished and subjected to static leach tests for varying periods of time in an HCl solution (pH 4) at 90°C. The presence of an alteration layer on the leached specimens was independently confirmed using infrared spectroscopy. These samples were then analyzed with neutron depth profiling (NDP), and for all exposure times between 1 and 20 h, a leached layer was detected by NDP. The residual concentration of ⁶Li in the alteration layer was observed to be approximately 10% of the bulk glass value. The 7.5 h and 17.5 h samples were cross-sectioned using focused ion beam milling, and the thickness of the alteration layer on the samples was measured directly using scanning electron microscopy to be 9.8 and 22.9 μm, respectively. The areal density of the gel layers — determined by deconvolution of the NDP spectra — was coupled with the SEM measurement to give densities of 1.46 ± 0.08 g/cm³ for the 7.5 h specimen and 1.46 ± 0.05 g/cm³ for the 17.5 h specimen. This preliminary work shows that NDP can be used to determine the average density of gel layers formed owing to leaching of alkali-silicate glass.