Effect of age, sex and gender on pain sensitivity: A narrative review

© 2017 Eltumi And Tashani. Introduction: An increasing body of literature on sex and gender differences in pain sensitivity has been accumulated in recent years. There is also evidence from epidemiological research that painful conditions are more prevalent in older people. The aim of this narrative review is to critically appraise the relevant literature investigating the presence of age and sex differences in clinical and experimental pain conditions. Methods: A scoping search of the literature identifying relevant peer reviewed articles was conducted on May 2016. Information and evidence from the key articles were narratively described and data was quantitatively synthesised to identify gaps of knowledge in the research literature concerning age and sex differences in pain responses. Results: This critical appraisal of the literature suggests that the results of the experimental and clinical studies regarding age and sex differences in pain contain some contradictions as far as age differences in pain are concerned. While data from the clinical studies are more consistent and seem to point towards the fact that chronic pain prevalence increases in the elderly findings from the experimental studies on the other hand were inconsistent, with pain threshold increasing with age in some studies and decreasing with age in others. Conclusion: There is a need for further research using the latest advanced quantitative sensory testing protocols to measure the function of small nerve fibres that are involved in nociception and pain sensitivity across the human life span. Implications: Findings from these studies should feed into and inform evidence emerging from other types of studies (e.g. brain imaging technique and psychometrics) suggesting that pain in the older humans may have unique characteristics that affect how old patients respond to intervention

Comparison study of nucleation and growth characteristics of chemical-vapor-deposited diamond films on CoSi2(001) and Si(001)

Epitaxial CoSi2 (001) layers, deposited on Si(001) substrates by molecular beam allotaxy, were used as substrates for diamond deposition in order to realize applications. The nucleation and textured growth of diamond films were compared with those on the Si(001) substrates. The results indicate that in a microwave-plasma chamber diamond can be nucleated with a higher density on CoSi2 at lower temperatures using a bias-enhanced method. High-quality [001]-textured diamond films can be synthesized on CoSi2 (001) using the [001]-textured growth conditions. So far, epitaxial growth of diamond on CoSi2 cannot be observed. Statistically, a rotating angle distribution of diamond grains around the [001] axis in a [001]-textured film shows, however, preferred in-plane orientations of 13 degrees, 22 degrees, 45 degrees, and 77 degrees relative to the CoSi2 [011] axis. The structural and chemical analyses show that no Co and Si element diffusion from the CoSi2 substrate into the diamond film can be detected. The films grown on CoSi2 have similar crystal quality to that of epitaxial films deposited directly on Si. (C) 2000 American Institute of Physics. [S0021-8979(00)10203-8]

The effect of the reaction temperature on the thermal stability of polycrystalline CoSi2 layers on Si(001)

We investigated the solid state reaction of 30-nm and 100-nm-thick silicide layers on single-crystalline silicon in the temperature range between 650 and 800 degreesC using transmission electron microscopy and atomic force microscopy. Sheet resistance measurements were used to observe the effect of the reaction temperature on the layer properties and to perform a systematic study on the thermal stability. At the lower reaction temperature good quality layers were produced with quite small grains. The specific resistivity is as low as 15 mu Omega cm and the interface to the silicon substrate is quite flat. These favourable properties lead to a high thermal stability. The processed layers are stable in the temperature range between 850 and 950 degreesC. When the layer thickness is increased to 100 nm, the stability range extends by about 250 degreesC. The deterioration rate of 30-nm and 100-nm-thick silicide layers was deduced from sheet resistance measurements. The activation energy for the electrical degradation of the layer due to layer agglomeration was found to be nearly independent of the thickness. (C) 2001 Elsevier Science B.V. All rights reserved

Ultrafast silicon based photodetectors

We have fabricated different metal-silicon-metal photodetectors and characterized these devices for visible and near-infrared (IR) response. For wavelengths shorter than 1.1 mu m. electron-hole pairs are generated in the Si. They are accelerated to saturation velocity and move towards the metal electrodes. For longer wavelengths, Si itself becomes transparent, but carriers are emitted from the internal semiconductor-metal interfaces. This so-called "internal photoeffect" is governed by different carrier dynamics, because "hot" electrons or holes are injected into the Si. Their significant excess energy leads to extremely fast electrical pulses. The resulting temporal response was measured with a new setup, using a Ti:sapphire laser and an optical parametric oscillator. which generates ultrafast optical pulses (170 fs) at IR wavelengths. Schottky-barrier emission from CoSi2, Cr, Ti, and Pt was investigated. A photodetector from Ti-Si-CoSi2 was excited with optical pulses of 1250 nm and showed an electrical pulse response of 3.2 ps full width at half maximum at 4 V bias. This is a record value. We can demonstrate, that under certain conditions an even faster response becomes possible. (C) 2000 American Vacuum Society. [S0734-2101(00)04702-3]