An Introduction to Light Interaction with Human Skin

Despite the notable progress in physically-based rendering, there is still a long way to go before one can automatically generate predictable images of organic materials such as human skin. In this tutorial, the main physical and biological aspects involved in the processes of propagation and absorption of light by skin tissues are examined. These processes affect not only skin appearance, but also its health. For this reason, they have also been the object of study in biomedical research. The models of light interaction with human skin developed by the biomedical community are mainly aimed at the simulation of skin spectral properties which are used to determine the concentration and distribution of various substances. In computer graphics, the focus has been on the simulation of light scattering properties that affect skin appearance. Computer models used to simulate these spectral and scattering properties are described in this tutorial, and their strengths and limitations discussed. Keywords: natural phenomena, biologically and physically-based rendering

Crack-tip deformation field measurements using coherent gradient sensing

A real time, full field, lateral shearing interferometry - coherent gradient sensing (CGS) - has recently been developed for investigating fracture in transparent and opaque solids. The resulting interference patterns are related to the mechanical fields by means of a first order diffraction analysis. The method has been successfully applied to quasi-static and dynamic crack tip deformation field mapping in homogeneous and bimaterial fracture specimens

Structures of some surfactant-polyelectrolyte complexes

Structures of complexes formed in aqueous solutions by some anionic polyelectrolytes (double and single stranded (ds and ss) DNA, poly(vinyl sulfonate) (PVS), and poly(styrene sulfonate) (PSS)) with a cationic surfactant system consisting of cetyltrimethylammonium bromide (CTAB) and sodium 3-hydroxy-2-naphthoate (SHN) have been determined using small angle X-ray diffraction. All complexes are found to have a two-dimensional (2-D) hexagonal structure at low SHN concentrations. Analysis of the diffraction data shows that the ds DNA-CTAB complex has an intercalated structure, with each DNA strand surrounded by three cylindrical micelles. On increasing SHN concentration, DNA-CTAB-SHN complexes exhibit a hexagonal-to-lamellar transition, whereas PVS complexes show a hexagonal → centered rectangular → lamellar transition. PSS complexes show yet another sequence of structures. These results indicate the significant influence of the chemical nature of the polyelectrolyte on the structure of the complexes

Reentrant phase transitions of DNA-surfactant complexes

Complexes of double-stranded DNA with the cationic surfactant cetyltrimethylammonium bromide have been studied using small angle X-ray diffraction at varying concentrations of DNA and the cosurfactant hexanol. At low DNA concentrations, an intercalated hexagonal (HIc)→lamellar (Lαc)→inverted hexagonal (HIIc) transformation is found on increasing hexanol content. The HIIc structure is converted into Lαc on adding more DNA. Further increase in hexanol content leads to a phase separation in the surfactant solution, and a reentrant Lαc→HIIc→Lαc transition is observed as DNA concentration is increased. Such structural transformations of DNA-surfactant complexes, driven by DNA concentration, have not been reported until now

Effect of turmeric and curcumin on BP-DNA adducts

Many human cancers that are widely prevalent today can be prevented through modifications in life-styles, of which diet appears to be an important agent. Several dietary constituents modulate the process of carcinogenesis and prevent genotoxicity. Many plant constituents including turmeric appear to be potent antimutagens and antioxidants. Therefore the modulatory effects of turmeric and curcumin on the levels of benzo[a]pyrene induced DNA adducts in the livers of rats were studied by the newly developed 32P-postlabelling assay method. Turmeric when fed at 0.1, 0.5 and 3% and the active principle of turmeric (curcumin) when fed at a level of 0.03% in the diet for 4 weeks significantly reduced the level of BP-DNA adducts including the major adduct dG-N2-BP, formed within 24 h in response to a single i.p. injection of benzo[a]pyrene. The significance of these effects in terms of the potential anticarcinogenic effects of turmeric is discussed. Further, these results strengthen the various other biological effects of turmeric which have direct relevance to anticarcinogenesis and chemoprevention

Data acquisition system for phase-2 KGF proton decay experiment

Phase-2 of KGF proton decay experiment using 4000 proportional counters will start operating from middle of 1985. The detection systems, in addition to measuring the time information to an accuracy of 200 n see, also records ionization in the hit counters. It also monitors different characteristics of the counters like pulse height spectrum, pulse width spectrum and counting rate. The acquisition system is discussed

Results on nucleon life-time from the Kolar gold field experiment

The KGF nucleon decay experiment has been in operation since October 1980 with a 140 ton calorimetric detector at a depth of 2.3 Km underground. The detector comprises 34 layers of proportional counters arranged in an orthogonal geometry with 12 mm thick iron plates in between successive layers. The proportional counters are made up of square (10 x 10 square centimeters) iron plates of wall thickness 2.3 mm. Each of the 1600 counters is instrumented to provide data on ionization, DE/dx and arrival time. The visible energy of a particle is determined to an accuracy of approximately 20% from the ionization and range of its track. The end point ionization of a stopping track provides the direction of motion as well as the nature of the particle (mu/pi,k,p). Decay of mu is recorded with an overall efficiency of only 20% in view of the thickness of 13 g/square centimeters between successive layers

Design and Implementation of Actor Based Parallel VHDL Simulator

Coordinated Science Laboratory was formerly known as Control Systems LaboratoryNational Science Foundation (NSF) / MIP-9320854Semiconductor Research Corporation / SRC 95-DP-109Advanced Research Projects Agency (ARPA) / DAA-H04-94-G-027

Muon and neutrino results from KGF experiment at a depth of 7000 hg/square cm

The KGF nucleon decay experiment at a depth of 7000 hg/sq cm has provided valuable data on muons and neutrinos. The detector comprised of 34 crossed layers of proportional counters (cross section 10 x 10 sq cm; lengths 4m and 6m) sandwiched between 1.2 cm thick iron plates can record tracks of charged particles to an accuracy of 1 deg from tracks that traverse the whole of the detector. A special two-fold coincidence system enables the detector to record charged particles that enter at very large zenith angles. In a live time of 3.6 years about 2600 events have been recorded. These events include atmospheric muons, neutrino induced muons from rock, stopping muons, showers and events which have their production vertex inside the detectors. The results on atmospheric muons and neutrino events are presented