Laser standards for medical purposes

The two standards to which medical lasers should be designed are IEC 601-1 (Medical Electrical Equipment, Part 1 General Requirements) and IEC 825 (Radiation Safety of Laser Products, Equipment Classification Requirements and User's Guide).These standards do not cover all the requirements so there is a Part 2 to IEC 601-1 being produced which also relates to IEC 825 which supplements, amends or deletes clauses in both main documents as applicable. This Part 2 is not expected to be available until August 1990 so until then it is the two main standards which should be applied as far as possible by manufacturers and test houses.With 1992 only two years away the European Community is trying to produce standards for use within the Community after that date. Clearly, to utilize existing standards from some member countries has attractions from an efficiency standpoint but it does mean that other countries have not had the opportunity of contributing to the standard and are presented with a fait accompli. A number of European countries are therefore fielding very strong teams of representatives to standards meetings to try and get their standards accepted as the European Norm.IEC 601-1 has just been revised and a 1988 edition is available but the 1977 edition is still in force, IEC 825 is undergoing revision so the position so the position is rather fluid. It is recommended that manufacturers design their equipment to the latest edition as there will be a changeover period during which both old or new standards are acceptable.     

The structure of events triggered by direct photons in π− p, π+ p andpp collisions at 280 GeV/c

The structure of events associated with the production of direct photons in π^? p, π⁺ p andpp reactions of 280 GeV/c has been studied using data from the WA 70 experiment at the CERN SPS. Results are presented on the distributions of the fractional momenta of the colliding partons and on the fragmentation of the recoil jet and a comparison is made with predictions using the structure functions of Duke and Owens in the Lund Monte Carlo with string fragmentation.     

Analysis of amphetamine and methamphetamine as emerging pollutants in wastewater and wastewater-impacted streams

The identification and quantitation of the non-ecstasy amphetamine-type stimulants (ATSs) amphetamine and methamphetamine in lakes, rivers, wastewater treatment plant influents, effluents, and biosolids are reviewed. Neither monitoring nor reporting is required of these ATSs, which are considered emerging pollutants, but they have been identified in the environment. Amphetamine and methamphetamine enter our water supply by human excretion after legal or illegal consumption and via manufacturing in clandestine laboratories. Analytical methodology for sampling, sample preparation, separation, and detection of ATSs is discussed. Reported occurrences of ATSs in the environment and their use in municipal sewage epidemiology are noted. Future research needs that challenge applications of analytical techniques are discussed. The review focuses on research reported from 2004 to 2009.     

Low frequency narrow-band calls in bottlenose dolphins (Tursiops truncatus): signal properties, function, and conservation implications

Dolphins routinely use sound for social purposes, foraging and navigating. These sounds are most commonly classified as whistles (tonal, frequency modulated, typical frequencies 5-10 kHz) or clicks (impulsed and mostly ultrasonic). However, some low frequency sounds have been documented in several species of dolphins. Low frequency sounds produced by bottlenose dolphins (Tursiops truncatus) were recorded in three locations along the Gulf of Mexico. Sounds were characterized as being tonal with low peak frequencies (mean?=?990 Hz), short duration (mean?=?0.069 s), highly harmonic, and being produced in trains. Sound duration, peak frequency and number of sounds in trains were not significantly different between Mississippi and the two West Florida sites, however, the time interval between sounds within trains in West Florida was significantly shorter than in Mississippi (t?=?-3.001, p?=?0.011). The sounds were significantly correlated with groups engaging in social activity (F=8.323, p=0.005). The peak frequencies of these sounds were below what is normally thought of as the range of good hearing in bottlenose dolphins, and are likely subject to masking by boat noise.     

Dielectrowetting driven spreading of droplets

The wetting of solid surfaces can be modified by altering the surface free energy balance between the solid, liquid, and vapor phases. Here we show that liquid dielectrophoresis induced by nonuniform electric fields can be used to enhance and control the wetting of dielectric liquids. In the limit of thick droplets, we show theoretically that the cosine of the contact angle follows a simple voltage squared relationship analogous to that found for electrowetting on dielectric. Experimental observations confirm this predicted dielectrowetting behavior and show that the induced wetting is reversible. Our findings provide a noncontact electrical actuation process for meniscus and droplet control.     

Breakup modes of a laminar hollow water jet

Graphical Abstract  

     

Surface valence states and stoichiometry of non-superconducting and superconducting FeTe films

We report the surface electronic structure and stoichiometry of FeTe films following the incorporation of oxygen by three different methods: air exposure, dry oxygen exposure and low temperature oxygen annealing. X-ray photoemission experiments show that oxygen incorporation changes the initial valence state of Fe from 0 to mainly 3+. We also observe that the Te changes valence from initially 0 to mixed 0 and 4+. The rate of valence changes is seen to depend on the method of incorporation. In addition, it is observed that the surface of the FeTe films is left in a Te deficient state following any type of exposure to oxygen.