Spectral analysis of human tremor during cognitive tasks.

Many stresses occur in our daily lives. Some of these are part of diseases of the nervous system such as ataxia and neuroses. Certain body tremors may be related to these stresses. The rhythmic movement of various muscle groups, similar to a fast circadian rhythm, is defined as a tremor. These tremors, occurring during cognitive tasks, have been recorded by one-dimensional accelerometer in use in our laboratory. In this expanded study, we recorded three-dimensional body displacements with an optical motion capture system while subjects were performing the tasks of intent listening, reading and mental arithmetic calculations. The recorded displacements were subjected to spectral analysis using the Fast Fourier transform (FFT). The results indicate that the body vibration amplitude spectrum caused by mental arithmetic is significantly increased in the frequency rage of 0.5 to 0.7 Hz, when compared to those recorded during other tasks. The induced tremor, as well as general invisible body micro-vibration, were obtained from the three-dimensional body displacements.

A Web-based home helper support system.

A web-based "Home Helper" support system has been developed for improving scheduling and record keeping efficiency and for eliminating unnecessary travel. This support system consists of a wireless internet mobile phone for each "Home Helper" and a server at the main office. After each visit, the Home Helpers send their care reports via the mobile phone to the office server. This server computer then creates the "filings" automatically and in appropriate format for insurance and government use.

A microcomputer-based data acquisition system for ECG, body and ambient temperatures measurement during bathing.

A data acquisition system employing a low power 8 bit microcomputer has been developed for heart rate variability monitoring before, during and after bathing. The system consists of three integral chest electrodes, two temperature sensors, an instrumentation amplifier, a low power 8-bit single chip microcomputer (SMC) and a 4 MB compact flash memory (CFM). The ECG from the electrodes is converted to an 8-bit digital format at a 1 ms rate by an A/D converter in the SMC. Both signals from the body and ambient temperature sensors are converted to an 8-bit digital format every 1 second. These data are stored by the CFM. The system is powered by a rechargeable 3.6 V lithium battery. The 4 x 11 x 1 cm system is encapsulated in epoxy and silicone, yielding a total volume of 44 cc. The weight is 100 g.

A microcontroller-based telemetry system for sympathetic nerve activity and ECG measurement.

A telemetry system employing a low power 8-bit microcontroller has been developed for chronic unanesthetized small animal studies. The two-channel system is designed for use with animals in shielded cages. Analog signals from implantable ECG and nerve electrodes are converted to an 8-bit serial digital format. This is accomplished by individual 8 bit A/D converters included in the microcontroller, which also has serial I/O port. The converted serial binary code is applied directly to an antenna wire. Therefore, the system does not need to employ a separate transmitter, such as in FM or infrared optical telemeters. The system is used in a shielded animal cage to reduce interference from external radio signals and 60 Hz power line fields. The code is received by a high input impedance amplifier in the cage and is then demodulated. The telemeter is powered by a small 3 V lithium battery, which provides 100 hours of continuous operation. The circuit is constructed on two 25 x 25 mm. printed circuit boards and encapsulated in epoxy, yielding a total volume of 6.25 cc. The weight is 15 g.

Effects of oxygen tension on flow-induced vasodilation in porcine coronary resistance arterioles.

Vascular tone has been shown to be importantly influenced by flow-induced release of endothelium-derived vasodilators. The purpose of the present study was to test the hypothesis that in porcine coronary resistance-size arterioles, flow-induced vasodilation is sensitive to oxygen tension. Arterioles (55-150 mu m) were studied in vitro under conditions of constant intraluminal pressure to dynamically measure arteriolar diameter in response to changes in flow or, alternatively, in response to bradykinin under three conditions: hyperoxia (pO(2) 400 mm Hg), normoxia (pO(2) 160 mm Hg), and hypoxia (p0(2) 40 mm Hg). Under conditions of constant pressure and no flow, hypoxia alone resulted in vasodilation that was blocked by the nitric oxide synthase inhibitor omega-nitro-L-arginine methyl ester (L-NAME). Hypoxia did not alter the vasodilator response to bradykinin when compared to the vasodilator response to bradykinin during normoxia. During hyperoxia, flow-induced vasodilation was significantly reduced by either indomethacin, or L-NAME. Indomethacin and L-NAME combined completely abolished flow-induced vasodilation under conditions of hyperoxia. Under conditions of normoxia and hypoxia, indomethacin or L-NAME alone only partially blocked flow-induced vasodilation. No further inhibition was observed when indomethacin and L-NAME were combined. Glybenclamide failed to alter flow-induced vasodilation either alone or in combination with indomethacin and L-NAME. The results suggest that the mechanisms responsible for flow-induced vasodilation in coronary arterioles are complex and are different depending upon the oxygen tension. During hyperoxia, vasodilation is due to the combined actions of prostanoids and nitric oxide, while under conditions of normoxia and hypoxia, flow-induced vasodilation is the result of not only prostanoids and nitric oxide, but of another as of yet unidentified oxygen-sensitive endogenous vasodilator.

A new detection method of ultrasonic flowmeter beam incident angle.

We have developed a new method of continuously measuring the angle between a pulsed Doppler blood flowmeter ultrasonic beam and the flow axis for precise blood flow velocity measurements. The transducer employed in the flowmeter system design is formed by two LZT 10 MHz crystals held in a lightweight polystyrene shell. Recessed internal cavities in the shell hold one 10 MHz crystal at a 45 degree angle for blood flow velocity measurement and the other crystal at a 90 degree angle for beam angle detection. The angle and Doppler frequency are supplied to a digital signal processor to precisely calculate instantaneous flow velocity. This automatic angle correction system is designed for applications where the transducer-flow angle is subject to change. Typical use examples are half-cylinder flow transducers that do not encircle the artery and external, hand-held, transcutaneous transducers.

Supercritical fluid extraction of chemical warfare agent simulants from soil.

Chemical warfare agent simulants are efficiently recovered from 2-ppm spikes in 1 g of Rocky Mountain Arsenal Standard Soil using methanol-carbon dioxide (5:95) at 300 atm for 2 min at 60 degrees C. Recoveries (n = 3) were 79 +/- 23% for dimethylmethylphosphonate, 93 +/- 14% for 2-chloroethylethyl sulfide, 92 +/- 13% for diisopropylfluorophosphate and 95 +/- 17% for diisopropylmethylphosphonate. Recoveries are higher than, but less precise than those achieved from a 5-min ultrasonic micro-scale extraction using methanol. Much less laboratory waste is generated than the current standard organic solvent extraction method (33 g of soil shaken with 100 ml of chloroform).

Digital processing of equine exercise electrocardiograms.

We have developed and used a system for recording and analyzing the electrocardiogram (ECG) of the horse during exercise. The system consists of a commercial ECG transmitter telemetering a Z lead (base-apex) ECG from an exercising horse. The received data are then remodulated at an audio frequency and stored on a audio cassette recorder. Exercise protocols of up to 10 minutes are digitized using a Macintosh II computer. For rhythm analysis, a computer program to identify the various waves of the ECG uses a modification and refinement of the integrated-squared-derivative (ISD) technique. This technique consists of frequency selective digital filtering and differentiation followed by integration of the squared derivative. The waves of the ECG are identified using adaptive thresholding of the ISD and the derivative of the ECG. Thus far, we have been able to successfully identify the Q, R, and the end of T in ECGs severely contaminated by exercise artifact. The system can place the absolute time of occurrence of the Q, R, and end of T in a text file for export to other analysis programs such as spreadsheets and statistics packages.

Liquid chromatographic determination of total formaldehyde in drinking water.

Formaldehyde is readily quantitated at micrograms/L levels in drinking water. The analyte present in 1 L water samples is derivatized with 2,4-dinitrophenylhydrazine in a 2M acid medium and then extracted with chloroform. After the solvent is exchanged for methanol, the product is separated and quantitated using reverse-phase liquid chromatography with UV detection (365 nm). Reporting limits as low as 20 micrograms/L (corrected for laboratory blank) are routinely achieved. Formaldehyde recovery typically exceeds 90% at 20-200 micrograms/L. The method was applied to hot and cold water samples from thirty-four 1- and 2-story houses equipped with poly(acetal) plumbing elbows and tees. The drinking water samples were accompanied by sets of blanks and spikes specified by a quality assurance/quality control plan. Formaldehyde was observed above the reporting limit in 80% of hot and cold water samples from the 1-story dwellings, but in less than 50% of those from the 2-story dwellings. The results may depend on both the construction of the houses (1- vs 2-story) and the time of year the water is sampled (mid-summer).

An automatic syringe for coronary occlusion in long-term collateralization studies.

A portable apparatus for performing repeated, brief coronary artery occlusions automatically in long-term chronic studies involving dogs and larger animals is described. The battery-operated, back-pack-carried device uses a motorized syringe driven by a digital-programmable timing circuit to inflate a coronary artery occluder for durations of 10 s to 3 min at intervals from 14 s to 16 h. A single battery charge produces 450 occlusions. The generated pressure is adjustable to 1,000 mmHg maximum. A separate fail-safe circuit monitors system operation to open a pressure-relief valve if occlusions exceed a preset duration.

A miniaturized ultrasonic flowmeter and telemetry transmitter for chronic animal blood flow measurements.

An ultrasonic blood flowmeter telemetry system, using only two integrated circuits and one transistor, has been designed for chronic unanesthetized animal studies. Standard components and construction techniques are utilized. The CW Doppler system employs LZT piezoelectric 10 MHZ transmitting and receiving crystals held in a lightweight polystyrene arterial transducer. The audio frequency, FM Doppler signal modulates an FM oscillator-transmitter to produce an FM/FM radio frequency carrier which is transmitted to an FM receiver at a remote location. The transmitted Doppler audio flow signal is demodulated at the receiver by a zero crossing detector. Power consumption is 48 mw. The 12.4 cc package volume can be further reduced for animal implantation.

DC proportional heater-cooler temperature controlled for physiological research.

A DC proportional temperature control circuit for driving resistive heaters and Peltier thermoelectric devices in physiological research is described. The instrument, supplying +/- 12.5 V DC at 8 A is designed for temperature control of anesthetized animals, generation of hot or cold thermal stimuli, and control of thermal environments.