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At least 505 records · Page 28Linked to original sources
PubMed2006

Analog signal acquisition from computer optical disk drives for quantitative chemical sensing.

Optoelectronic consumer products that are widely employed in the office and home attract attention for optical sensor applications due to (1) their cost advantage over analytical instruments produced only in small quantities, (2) robustness in operation due to the detailed manufacturability improvements, and (3) ease of operation. We demonstrate here a new approach for quantitative chemical/biochemical sensing when analog signals are acquired from conventional optical disk drives, and these signals are used for quantitative detection of optical changes of sensor films deposited on conventional CD and DVD optical disks. Because we do not alter manufacturing process of optical disks, any disk can be employed for deposition and readout of sensor films. The optical disk drives also perform their original function of reading and writing digital content to optical media because no optical modifications are introduced to obtain the analog signal. Such a sensor platform is quite universal and can be applied for chemical and biological quantitative detection, as well as for monitoring of changes of physical properties of regions deposited onto a CD or DVD (e.g., during combinatorial screening of materials). As a model example, we demonstrate the concept using chemical detection of ionic species such as Ca2+ in liquids (e.g., blood, urine, or water). Colorimetric calcium-sensitive sensor films were deposited onto a DVD, exposed to water with different concentrations of Ca2+, and quantified in the optical disk drive. The developed lab-on-DVD system demonstrated a 5 ppm detection limit of Ca2+ determinations, similar or slightly better than that achieved using a conventional fiber-optic portable spectrometer. This detection limit corresponded to a 0.023 absorbance unit resolution, as determined by the measurement of the same colorimetric films with a portable spectrometer. Determinations of Ca2+ unknowns using the lab-on-DVD system demonstrated +/-5 ppm accuracy and 2-5% relative standard deviation precision in predicting 100 ppm Ca2+.

Biosensing Techniques↗
PubMed2003

Tuned-aperture computed tomography versus parallax analog and digital radiographic images in detecting second mesiobuccal canals in maxillary first molars.

OBJECTIVE: We sought to evaluate the detectability of second mesiobuccal (MB2) canals in the MB root of maxillary first molar teeth by comparing (1) parallax with pairs of conventional direct-exposure film intraoral radiographs (both D-speed and F-speed), (2) parallax with pairs of charge-coupled device-based digital images acquired through the use of Trophy RVG-ui, and (3) charge-coupled device-based images acquired through the use of a Trophy RVG-ui sensor and tomosynthetically reconstructed by TACT (tuned-aperture computed tomography) Workbench Software. STUDY DESIGN: Maxillary first molars were mounted in simulated bone. Pairs of images were generated by conventional D-speed and F-speed radiography and digital radiography with a charge-coupled device-based sensor, the RVG-ui. Sequences of images were also acquired for TACT reconstruction by using the digital sensor. Observers viewed sets of images to determine the number of canals present within the MB root of each tooth. Roots were horizontally cross-sectioned and viewed under an operating microscope to determine the actual number of canals present. RESULTS: The frequency of detection of MB2 canals was remarkably similar across techniques: 39.2% to 39.6% with parallax for both types of film and for RVG-ui images, and 37.9% with TACT. No statistically significant difference was found in the detectability of MB2 canals between the modalities tested. TACT had higher correlation coefficients than the other 3 modalities with respect to intrarater and interrater reliabilities. CONCLUSIONS: (1) There was a less than 40% chance of locating MB2 canals in the MB root of maxillary first molar teeth by using parallax with pairs of digital or analog radiographs. (2) TACT did not significantly affect the rate of detection of MB2 canals.

Analysis of Variance↗
PubMed1997

An analog memory circuit for spiking silicon neurons.

A simple circuit is described that functions as an analog memory whose state and dynamics are directly controlled by pulsatile inputs. The circuit has been incorporated into a silicon neuron with a spatially extensive dendritic tree as a means of controlling the spike firing threshold of an integrate-and-fire soma. Spiking activity generated by the neuron itself and by other units in a network can thereby regulate the neuron's excitability over time periods ranging from milliseconds to many minutes. Experimental results are presented showing applications to temporal edge sharpening, bistable behavior, and a network that learns in the manner of classical conditioning.

Action Potentials↗
PubMedDate not supplied

[Analog gamma camera digitalization computer system].

OBJECTIVE: Digitalization of analogue gamma cameras systems, using special acquisition boards in microcomputers and appropriate software for acquisition and processing of nuclear medicine images is described in detail. MATERIAL AND METHODS: Microcomputer integrated systems interconnected by means of a Local Area Network (LAN) and connected to several gamma cameras have been implemented using specialized acquisition boards. The PIP software (Portable Image Processing) was installed on each microcomputer to acquire and preprocess the nuclear medicine images. A specialized image processing software has been designed and developed for these purposes. This software allows processing of each nuclear medicine exam, in a semiautomatic procedure, and recording of the results on radiological films. RESULTS: . A stable, flexible and inexpensive system which makes it possible to digitize, visualize, process, and print nuclear medicine images obtained from analogue gamma cameras was implemented in the Nuclear Medicine Division. Such a system yields higher quality images than those obtained with analogue cameras while keeping operating costs considerably lower (filming: 24.6%, fixing 48.2% and developing 26%.) CONCLUSIONS: Analogue gamma camera systems can be digitalized economically. This system makes it possible to obtain optimal clinical quality nuclear medicine images, to increase the acquisition and processing efficiency, and to reduce the steps involved in each exam.

Computers↗