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New hope for identifying the unidentified. The National Crime Information Center unidentified person/missing person files.

The National Crime Information Center Unidentified Person/Missing Person Files offer computer comparison of descriptive data on unidentified dead and living persons with data entered on missing persons. Completion of a simple, but detailed standard form allows entry of descriptors of physical characteristics, fingerprint classification, dentition, anthropologic and x-ray findings, optic prescriptions, medical devices, surgical procedures, serology, jewelry, and clothes. Medical and law enforcement agencies collect the descriptive data on the unidentified; families and law enforcement agencies collect missing persons information. Entry for both is via law enforcement regional or state NCIC computer terminals. Continuous comparison and cross search of both files is initiated upon entry of either form.

Autopsy↗

Halothane and the beating response and ATP turnover rate of heart cells in tissue culture.

The effects of halothane on the beating response of rat heart cells in tissue culture were studied using an optical-electronic monitoring device. A dose-response curve was obtained over a concentration range to as much as 5 vol per cent halothane. The clinical dosage of 1 vol per cent halothane decreased the inotropic response of 4-10-day-old cells to 59 plus or minus 10 per cent of the original beating strength; no significant decrease in beating strength was seen in 25-30-day-old cells. One volume per cent halothane caused no significant change in the chronotropic response of the heart cells. Higher concentrations of halothane caused significant negative chronotropic and negative inotropic responses in a dose-related manner. When glycolysis was inhibited by 2-deoxyglucose in the growth medium, the cells became dependent on fatty-acid oxidation and oxidative phorphorylation for energy and showed increased sensitivity to halothane; for example, the chronotropic response to 5-8-day old cells treated with 2-deoxyglucose was decreased approximately 70 per cent by exposure to 3 vol per cent halothane, whereas 4-10-day-old cells maintained on a complete growth medium showed only a 40 per cent decrease. Increasing concentrations of halothane decreased the rate of ATP turnover. This supports evidence suggesting that halothane blocks electron transport in the NADH-coenzyme Q reductase level. The model described provides a means for determining anesthetic potency in a mammalian system in terms of functional as well as metabolic responses. It also provides a means for study of metabolic effects of anesthetics and other drugs.

Adenosine Triphosphate↗

XAS of dilute biological samples.

The experimental setup of beamline ID26 at ESRF (Grenoble) has been successfully exploited to obtain high-quality XAS (X-ray absorption spectroscopy) data from a biological sample where the metal concentration is about 100 micro M. The sample consists of the adenosine monophosphate deaminase (AMPD) histidine proline rich glycoprotein (HPRG) complex that contains 3-4 Zn(II) ions per dimer of approximately 320 kDa molecular weight. The experiment shows that third-generation X-ray sources equipped with insertion devices and appropriate optics and detectors allow the investigation of complex biological systems where the metal concentration is intrinsically low. The availability of such experimental setups makes possible a completely new set of experiments in biological XAS.

AMP Deaminase↗

Counting statistics of X-ray detectors at high counting rates.

Modern synchrotron radiation sources with insertion devices and focusing optics produce high fluxes of X-rays at the sample, which leads to a requirement for photon-counting detectors to operate at high counting rates. With high counting rates there can be significant non-linearity in the response of the detector to incident X-ray flux, where this non-linearity is caused by the overlap of the electronic pulses that are produced by each X-ray. A model that describes the overlap of detector pulses is developed in this paper. This model predicts that the correction to the counting rate for pulse overlap is the same as a conventional dead-time correction. The model is also used to calculate the statistical uncertainty of a measurement and predicts that the error associated with a measurement can be increased significantly over that predicted by Poisson (N(-1/2)) statistics. The error differs from that predicted by a conventional dead-time treatment.

Journal Article↗

A liquid-He cryostat for structural and thermal disorder studies by X-ray absorption.

A new device operating from 4.2 to 300 K is now installed on the hard X-ray station of the DCI ring in LURE in order to measure absorption coefficients. This liquid-He bath device has three optical windows. One allows the incident beam to impinge on the sample, one located at 180 degrees with respect to the sample allows transmitted beams to be detected, and another located at 90 degrees is used to detect emitted photons. Total electron yield detection mode is also possible thanks to a specific sample holder equipped with an electrode that collects the charges created by the emitted electrons in the He gas brought from the He bath around the sample. The performance of the cryostat is described by measurements of the absorption coefficients versus the temperature for Cu and Co foils. For comparison, the absorption coefficient is also measured for Cu clusters. As expected from dimension effects, the Debye temperature obtained for the clusters is lower than that of bulk Cu.

Journal Article↗

New techniques for predicting solar proton fluences for radiation effects applications.

At geosynchronous altitudes, solar proton events can be a significant source of radiation exposure for devices such as optical imagers, memories and solar cells. These events appear to occur randomly with respect to time and magnitude during the active period of each solar cycle. New probabilistic descriptions, including extreme value theory, are given in forms applicable to assessing mission risks for both single events and the cumulative fluence of multiple events. The analyses yield simpler forms than previous models, include more recent data, and can easily be incorporated into existing computer programs.

Electronics↗

Computer hardware and software to assist the visually impaired and blind.

Modern developments in computer hardware and software for the business world have been adapted to allow the partially sighted and blind to participate successfully in computer usage in education, employment and recreation. Adaptations such as the enlargement of the whole screen display, production of enlarged print and voice output of screen contents can assist the partially sighted. Conversion of computer screen information into speech or braille can be used in conjunction with sound boards and touch pads to allow the totally blind access to the exact spatial layout of screen contents. Optical character recognition devices whereby the printed page can be accessed by computer, and recent voice recognition techniques which allow a computer to interpret voiced commands, can also be used to assist the totally blind. Developments in these areas are discussed together with specific examples of equipment now available which make use of the various methods described.

Blindness↗

Low vision in east African blind school students: need for optical low vision services.

AIMS: There is increasing awareness of the needs of children with low vision, particularly in developing countries where programmes of integrated education are being developed. However, appropriate low vision services are usually not available or affordable. The aims of this study were, firstly, to assess the need for spectacles and optical low vision devices in students with low vision in schools for the blind in Kenya and Uganda; secondly, to evaluate inexpensive locally produced low vision devices; and, finally, to evaluate simple methods of identifying those low vision students who could read N5 to N8 print after low vision assessment. METHODS: A total of 230 students were examined (51 school and 16 university students in Uganda and 163 students in Kenya, aged 5-22 years), 147 of whom had a visual acuity of less than 6/18 to perception of light in the better eye at presentation. After refraction seven of the 147 achieved 6/18 or better. Eighty two (58.6%) of the 140 students with low vision (corrected visual acuity in the better eye of less than 6/18 to light perception) had refractive errors of more than 2 dioptres in the better eye, and 38 (27.1%) had more than 2 dioptres of astigmatism. RESULTS: Forty six per cent of students with low vision (n = 64) could read N5-N8 print unaided or with spectacles, as could a further 33% (n = 46) with low vision devices. Low vision devices were indicated in a total of 50 students (35.7%). The locally manufactured devices could meet two thirds of the need. CONCLUSION: A corrected distance acuity of 1/60 or better had a sensitivity of 99.1% and a specificity of 56.7% in predicting the ability to discern N8 print or better. The ability to perform at least two of the three simple tests of functional vision had a sensitivity of 95.5% and a specificity of 63.3% in identifying the students able to discern N8 or better.

Adolescent↗

An inexpensive, high output voltage, voltage clamp for epithelial membranes.

A circuit is described that can produce a high output voltage to automatically short-circuit an epithelial tissue mounted in an Ussing chamber. Because of its high output voltage it can short-circuit preparations requiring over 500 muA even in conjunction with high-resistance agar bridges. The circuit, which is easy to build, uses an inexpensive, low-voltage, integrated circuit operational amplifier, which is electrically isolated from the high-voltage part of the circuit by an optical isolator. The device can also be modified for use as a high impedance preamplifier for monitoring the spontaneous membrane potential.

Amplifiers, Electronic↗

Comparison of tumor and normal tissue oxygen tension measurements using OxyLite or microelectrodes in rodents.

In this study we compare oxygen tension (PO2) histograms measured with O2 microelectrodes and a new optical PO2 measurement device, the OxyLite, in normal tissues (mouse spleen and thymus) and in tumors (R3230Ac in rats) (n = 5-6). The transient response to glucose infusion or 100% O2 breathing (hyperoxia) was also measured in tumors. PO2 histograms of spleen and thymus with the two devices were not different. The OxyLite tumor PO2 histogram, however, was left-shifted compared with the microelectrode (median PO2 1.0 vs. 4.0 mmHg, P = 0.016). Both probes responded to acute hyperglycemia with a mean increase of 3-6 mmHg, but the microelectrode change was not significant. The OxyLite consistently recorded large PO2 increases (approximately 28 mmHg) with hyperoxia, whereas the microelectrode response was variable. The OxyLite averages PO2 over an area that contains interstitial and vascular components, whereas the microelectrode measures a more local PO2. This study demonstrates the importance of considering the features of the measurement device when studying tissues with heterogeneous PO2 distributions (e.g., tumors).

Adenocarcinoma↗

Support for patients loosing sight.

This overview on support of patients loosing sight is based on a literature survey regarding reading disabilities and orientation and on results of experience trials performed at the University Eye Clinic Tübingen. In reading disorders, the main goal of rehabilitation is to regain or maintain the ability to read newspaper print. The fundament of rehabilitation is the use of optical and electronical devices and the application of specially designed training programs. The ability of a person with low vision to achieve successful orientation and mobility rehabilitation depends on residual vision, posture and balance, body image, auditory and tactile abilities, intelligence and personality. Rehabilitation efforts focus on the enhancement of residual vision applying magnifying contrast-enhancing and photomultiplying devices. The main pillar of orientation and mobility rehabilitation is a training especially designed for the patient's needs. Rehabilitation efforts must be tailored to the type of vision loss and to specific functional implications--the success rate is high. An optimal fitting of the required spectrum of low vision aids should be provided to the patient and importantly, professional teaching and training is recommended. Activities of daily living, orientation and mobility, and psychological concerns must be addressed. Close cooperation with other branches of rehabilitation is essential.

Humans↗

Telemedicine in the service of peace.

Ophthalmology is well suited to telemedicine, since optical and imaging devices provide the basis for virtually all ophthalmic patient evaluations. We established the Middle East Ophthalmology Network among ophthalmologists working in 10 major ophthalmology centres in Israel, Jordan, Morocco, the Palestinian Authority and Tunisia. The project offered some 50 physicians around the Middle East the opportunity to benefit from sharing clinical consultation for diagnosis and management decisions beyond physical and political boundaries. In the first year, over 100 consultations took place. The system overcame some of the constraints imposed by the uneven distribution of medical resources and expertise in the region, reduced professional isolation, encouraged more collaboration between physicians and offered peace dividends from cooperation between physicians across the political divide.

Humans↗

Imaging brain injury using time-resolved near infrared light scanning.

Conventional brain imaging modalities are limited in that they image only secondary physical manifestations of brain injury, which may occur well after the actual insult to the brain and represent irreversible structural changes. A real-time continuous bedside monitor that images functional changes in cerebral blood flow or oxygenation might allow for recognition of brain tissue ischemia or hypoxia before the development of irreversible injury. Visible and near infrared light pass through human bone and tissue in small amounts, and the emerging light can be used to form images of the interior structure of the tissue and measure tissue blood flow and oxygen utilization based on light absorbance and scattering. We developed a portable time-of-flight and absorbance system which emits pulses of near infrared light into tissue and measures the transit time of photons through the tissue. Images can then be reconstructed mathematically using either absorbance or scattering information. Pathologic brain specimens from adult sheep and human newborns were studied with this device using rotational optical tomography. Images generated from these optical scans show that neonatal brain injuries such as subependymal and intraventricular hemorrhages can be successfully identified and localized. Resolution of this system appears to be better than 1 cm at a tissue depth of 5 cm, which should be sufficient for imaging some brain lesions as well as for detection of regional changes in cerebral blood flow and oxygenation. We conclude that light-based imaging of cerebral structure and function is feasible and may permit identification of patients with impending brain injury as well as monitoring of the efficacy of intervention. Construction of real-time images of brain structure and function is now underway using a fiber optic headband and nonmechanical rotational scanner allowing comfortable, unintrusive monitoring over extended periods of time.

Animals↗

Whole-field fluorescence microscope with digital micromirror device: imaging of biological samples.

We have developed a whole-field fluorescence microscope equipped with a Digital Micromirror Device to acquire optically sectioned images by using the fringe-projection technique and the phase-shift method. This system allows free control of optical sectioning strength through computer-controlled alteration of the fringe period projected onto a sample. We have employed this system to image viable cells expressing fluorescent proteins and discussed its biological applications.

Calcium↗

Simple portable lens meter.

A device measuring the optical power of simple lenses by means of moiré phenomena is described. The relevant equations are derived, and a working instrument is presented. A power measuring accuracy better than 0.25 m(-1) in the range of +/- 10 m(-1) is demonstrated.

Journal Article↗

Realization of a multichannel integrated Young interferometer chemical sensor.

We report on the design, realization, and characterization of a four-channel integrated optical Young interferometer device that enables simultaneous and independent monitoring of three binding processes. The generated interference pattern is recorded by a CCD camera and analyzed with a fast-Fourier-transform algorithm. We present a thorough theoretical analysis of such a device. The realized device is tested by monitoring glucose solutions that induce well defined phase changes between output channels. The simultaneous measurement of three different glucose concentrations shows the multipurpose feature of such devices. The observed errors, caused by the mismatching of spatial frequencies of individual interference patterns with those determined from the CCD camera, are reduced with different reduction schemes. The phase resolution for different pairs of channels was approximately 1 x 10(-4) fringes, which corresponds to a refractive-index resolution of approximately 8.5 x 10(-8). The measured sensitivity coefficient of the phase change versus refractive-index change of approximately 1.22 x 10(3) x 2pi agrees well with the calculated coefficient of approximately 1.20 x 10(3) x 2pi.

Interferometry↗

Optical rotatory-dispersion-type spatial light modulator and characteristics of the modulated light.

Among known temporal-spatial light modulation methods, there is no realistic method that can precisely control a light pulse simultaneously in the temporal and spatial domains. By careful consideration of the symmetries and topological properties of electromagnetic waves, a novel spatial light modulator has been developed to create different far-field patterns for each wavelength of linearly polarized light composed of various wavelength components. The system consists of an optical rotatory dispersion device, which is like a Faraday rotator, and a spatial light modulator with parallel-alignment nematic liquid-crystal cells. Numerical simulation results show the effectiveness of this new spatial light modulation method.

Journal Article↗

Evanescent-wave bonding between optical waveguides.

Forces arising from overlap between the guided waves of parallel, microphotonic waveguides are calculated. Both attractive and repulsive forces, determined by the choice of relative input phase, are found. Using realistic parameters for a silicon-on-insulator material system, we estimate that the forces are large enough to cause observable displacements. Our results illustrate the potential for a broader class of optically tunable microphotonic devices and microstructured artificial materials.

Journal Article↗