Development of a low profile laser Doppler probe for monitoring perfusion at the patient – mattress interface

The clinical importance of pressure ulcers is reviewed confirming the need for continuous monitoring of skin blood perfusion at the patient – mattress interface. The design of a low profile (H≈1mm) laser Doppler probe is then described together with the experimental setup used for evaluation. The results show that the performance of the new sensor does not vary significantly from that of currently available probes over a wide range of operating parameters. The authors conclude that the sensor design provides a low cost perfusion monitoring solution with potential to significantly reduce the risk of bed sores in hospital patients

Sensor corrections for Sea-Bird SBE-41CP and SBE-41 CTDs

Author Posting. © American Meteorological Society, 2007. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Atmospheric and Oceanic Technology 24 (2007): 1117-1130, doi:10.1175/JTECH2016.1.Sensor response corrections for two models of Sea-Bird Electronics, Inc., conductivity–temperature–depth (CTD) instruments (the SBE-41CP and SBE-41) designed for low-energy profiling applications were estimated and applied to oceanographic data. Three SBE-41CP CTDs mounted on prototype ice-tethered profilers deployed in the Arctic Ocean sampled diffusive thermohaline staircases and telemetered data to shore at their full 1-Hz resolution. Estimations of and corrections for finite thermistor time response, time shifts between when a parcel of water was sampled by the thermistor and when it was sampled by the conductivity cell, and the errors in salinity induced by the thermal inertia of the conductivity cell are developed with these data. In addition, thousands of profiles from Argo profiling floats equipped with SBE-41 CTDs were screened to select examples where thermally well-mixed surface layers overlaid strong thermoclines for which standard processing often yields spuriously fresh salinity estimates. Hundreds of profiles so identified are used to estimate and correct for the conductivity cell thermal mass error in SBE-41 CTDs.The National Ocean Partnership Program and the National Oceanic and Atmospheric Administration (NOAA) Office of Oceanic and Atmospheric Research funded this analysis. The ITP data were acquired under National Science Foundation (NSF) Grant OCE0324233

Development of a low profile laser Doppler probe for monitoring perfusion at the patient – mattress interface

The clinical importance of pressure ulcers is reviewed confirming the need for continuous monitoring of skin blood perfusion at the patient – mattress interface. The design of a low profile (H≈1mm) laser Doppler probe is then described together with the experimental setup used for evaluation. The results show that the performance of the new sensor does not vary significantly from that of currently available probes over a wide range of operating parameters. The authors conclude that the sensor design provides a low cost perfusion monitoring solution with potential to significantly reduce the risk of bed sores in hospital patients

Model of the response function of large mass bolometric detectors

Large mass bolometers are used in particle physics experiments to search for rare processes. By operating at low temperature, they are able to detect particle energies from few keV up to several MeV, measuring the temperature rise produced by the energy released. This study was performed on the bolometers of the CUORE experiment. The response function of these detectors is not linear in the energy range of interest, and it changes with the operating temperature. The non-linearity is found to be dominated by the thermistor and its biasing circuit. A method to obtain a linear response is the result of this work. It allows a great simplification of the data analysis.Comment: 7 pages, 13 figures. Changes wrt v1: two columns layout, corrected typos, increase of plot labels font, fixes in bibliograph

Genotoxic effects of low 2.45 GHz microwave radiation exposures on Sprague Dawley rats

This paper investigates the genotoxic effects of 2.45 GHz microwave (MW) radiation exposure at low specific absorption rates (SAR). 200 Sprague Dawley rats were exposed to SAR values between 0.48 and 4.30 W.kg-1 and the DNA of different tissues extracted, precipitated and quantified. Induced deoxyribonucleic acid (DNA) damages were assessed using the methods of DNA Direct Amplification of Length Polymorphisms (DALP) and the Single Cell Gel Electrophoresis (SCGE). Densitometric gel analysis demonstrated distinctly altered band patterns within the range of 40 and 120 bp in exposed samples and in the tail DNA of the same animals before exposure compared with control. Results were re-affirmed with SCGE (comet assay) for the same cells. Different tissues had different sensitivities to exposures with the brains having the highest. DNA damages were sex-independent. There was statistically significant difference in the Olive moment and % DNA in the tail of the exposed tissues compared with control (p < 0.05). Observed effects were attributed to magnetic field interactions and production of reactive oxygen species. We conclude that low SAR 2.45 GHz MW radiation exposures can induce DNA single strand breaks and the direct genome analysis of DNA of various tissues demonstrated potential for genotoxicity

Measurement of Gas Velocities in the Presence of Solids in the Riser of a Cold Flow Circulating Fluidized Bed

The local gas velocity and the intensity of the gas turbulence in a gas/solid flow are a required measurement in validating the gas and solids flow structure predicted by computational fluid dynamic (CFD) models in fluid bed and transport reactors. The high concentration and velocities of solids, however, make the use of traditional gas velocity measurement devices such as pitot tubes, hot wire anemometers and other such devices difficult. A method of determining these velocities has been devised at the National Energy Technology Laboratory employing tracer gas. The technique developed measures the time average local axial velocity gas component of a gas/solid flow using an injected tracer gas which induces changes in the heat transfer characteristics of the gas mixture. A small amount of helium is injected upstream a known distance from a self-heated thermistor. The thermistor, protected from the solids by means of a filter, is exposed to gases that are continuously extracted from the flow. Changes in the convective heat transfer characteristics of the gas are indicated by voltage variations across a Wheatstone bridge. When pulsed injections of helium are introduced to the riser flow the change in convective heat transfer coefficient of the gas can be rapidly and accurately determined with this instrument. By knowing the separation distance between the helium injection point and the thermistor extraction location as well as the time delay between injection and detection, the gas velocity can easily be calculated. Variations in the measured gas velocities also allow the turbulence intensity of the gas to be estimated

Diamond thin film temperature and heat-flux sensors

Diamond film temperature and heat-flux sensors are developed using a technology compatible with silicon integrated circuit processing. The technology involves diamond nucleation, patterning, doping, and metallization. Multi-sensor test chips were designed and fabricated to study the thermistor behavior. The minimum feature size (device width) for 1st and 2nd generation chips are 160 and 5 micron, respectively. The p-type diamond thermistors on the 1st generation test chip show temperature and response time ranges of 80-1270 K and 0.29-25 microseconds, respectively. An array of diamond thermistors, acting as heat flux sensors, was successfully fabricated on an oxidized Si rod with a diameter of 1 cm. Some problems were encountered in the patterning of the Pt/Ti ohmic contacts on the rod, due mainly to the surface roughness of the diamond film. The use of thermistors with a minimum width of 5 micron (to improve the spatial resolution of measurement) resulted in lithographic problems related to surface roughness of diamond films. We improved the mean surface roughness from 124 nm to 30 nm by using an ultra high nucleation density of 10(exp 11)/sq cm. To deposit thermistors with such small dimensions on a curved surface, a new 3-D diamond patterning technique is currently under development. This involves writing a diamond seed pattern directly on the curved surface by a computer-controlled nozzle

An algorithm to linearize the response function of bolometric detectors

Bolometric detectors are used in particle physics experiments to search for rare processes, like neutrinoless double-beta decay and dark-matter interactions. Operating in low-temperature conditions they are able to detect particles energies from few keV up to several MeV, measuring the temperature rise produced by the energy released. We studied the bolometers used in the CUORE experiment. The response function of these detectors is not linear in the energy range of interest: the measurement of the energy is complicated and the shape of the signal depends on the energy itself. The response function changes when the operating temperature changes. The non-linearity is found to be dominated by the thermistor and the biasing circuit used to operate these detectors. An algorithm to obtain a linear response is proposed, introducing new techniques for the data analysis