[Conducted energy weapons (CEW)].

Background: Conducted energy weapons (CEW, TASER) are increasingly used by law enforcement agencies in Germany. The CEWs are intended to reduce violence against police officers and to reduce moderate to severe injuries of police officers and aggressors. The delivery of repetitive electrical impulses causes neuromuscular paralysis and incapacitation; however, there are safety concerns due to deaths related to CEWs.

Mixed-Precision for Linear Solvers in Global Geophysical Flows.

Semi-implicit (SI) time-stepping schemes for atmosphere and ocean models require elliptic solvers that work efficiently on modern supercomputers. This paper reports our study of the potential computational savings when using mixed precision arithmetic in the elliptic solvers. Precision levels as low as half (16 bits) are used and a detailed evaluation of the impact of reduced precision on the solver convergence and the solution quality is performed.

Amelioration of Tau pathology and memory deficits by targeting 5-HT7 receptor.

Tauopathies comprise a heterogeneous family of neurodegenerative diseases characterized by pathological accumulation of hyperphosphorylated Tau protein. Pathological changes in serotonergic signaling have been associated with tauopathy etiology, but the underlying mechanisms remain poorly understood. Here, we studied the role of the serotonin receptor 7 (5-HT7R), in a mouse model of tauopathy induced by overexpressing the human Tau[R406W] mutant associated with inherited forms of frontotemporal dementia.

Finite element model determination of correction factors used for measurement of aortic diameter via conductance.

Traditional methods for estimating the slope alpha and offset volume Vp for determining real-time chamber volume by the conductance catheter technique are not suited to measurements made in the aorta due to the relatively low resistivity of the aortic wall. We developed three distinct three-dimensional finite element models of the conductance catheter and surrounding tissues in order to predict alpha and Vp and to examine the nature of the electric field near the aortic wall. A heterogeneous isotropic model of the catheter, aorta and surrounding tissues accurately predicted the values of alpha and Vp.

In vivo measurement of real-time aortic segmental volume using the conductance catheter.

The goal of this investigation was to determine if the conductance catheter technique for chamber volume measurement could be applied in vivo to determine real-time phasic aortic segmental volume. A four-electrode conductance catheter was used to measure time-varying resistance of the descending thoracic aorta in open-chest, anesthetized dogs. Resistance was converted to segmental volume and the slope correction factor (alpha) and parallel conductance volume (Vp) were determined.

Effects of physical parameters on the cylindrical model for volume measurement by conductance.

Despite its undisputed utility for determining changes in ventricular pressure-volume relationships, the conductance catheter technique has not been proven reliable for measuring absolute volume. This limitation is due to violations of the assumptions inherent in the cylindrical model on which the method is based (i.e.

In vitro and finite-element model investigation of the conductance technique for measurement of aortic segmental volume.

This investigation examined the feasibility of applying the conductance catheter technique for measurement of absolute aortic segmental volume. Aortic segment volume was estimated simultaneously in vitro by using the conductance catheter technique and sonomicrometer crystals. Experiments were performed in five isolated canine aortas.

Specific impedance of canine blood.

The specific impedance of canine erythrocytes suspended in plasma was measured in the frequency range from 5 kHz to 1 MHz in samples from three animals in the hematocrit range from zero to packed cells at a temperature of 39 degrees C; measurements were made with a conductivity cell using four electrodes and a current density of 21 microA/cm2. With the use of impedance spectroscopy, data were fitted to an equivalent circuit model; model parameters in turn were fitted as functions of hematocrit. The resultant model can be used to predict specific impedance (real and reactive components) as a function of hematocrit and frequency over a frequency range from 5 kHz to 1 MHz and a hematocrit range from 0 to 80.

Multifrequency characteristics of disposable and nondisposable EMG needle electrodes.

The physical properties of recording electrodes coupled with the input characteristics of recording amplifiers can affect motor unit parameters. In recent years, there has been increased use of disposable needle electrodes; thus, a comparison of impedance characteristics with disposable types is of interest. Impedances at 10, 100, 1000, and 10,000 Hz of eight different electrode models including concentric and monopolar, both disposable and reusable, were measured.

Complex bioelectric impedance measurement system for the frequency range from 5 Hz to 1 MHz.

Analytic techniques that have been successfully employed in materials science, and to a lesser extent in the study of biologic systems, have potential for improving the application of bioelectric impedance provided that both real and imaginary impedance components can be measured with sufficient accuracy over a given frequency range. Since biologic tissue, particularly animal tissue, is typically highly conductive, phase angles are small, making accurate measurements difficult. A practical four-terminal system employing commercial lock-in amplifiers is described and error sources and corrective techniques are discussed.

Determination of tissue viability in experimental electrical injuries.

Electrical burns or ischemia (induced by vascular ligation) were produced in the legs of 15 anesthetized dogs to study evolution of tissue changes compared with impedance alterations. After the application of 1-ampere currents at 60 Hz, animals were monitored from 1 to 4 days. Muscle impendance was measured with frequency sweeping to determine tissue destruction.

Methods of complex impedance measurements in biologic tissue.

Bioelectric impedance measurements have been used to monitor a variety of physiologic events. While important insights have been gained and useful techniques developed, there are a number of limitations to the methods usually employed. Among these are the inability to define current pathways in complex systems and the inability to distinguish between volumetric changes and materials property changes.

Cancellation of coherent line-frequency noise in evoked potential recordings.

A stimulator for evoked potential recording can become synchronized with the fundamental or harmonics of the line frequency, thus introducing interference which cannot be removed by averaging. Synchronizing the stimulus alternately to the positive-going and negative-going zero-crossing of the line will reduce 60 Hz and odd harmonics, but will not reduce higher even-harmonics. This communication describes a circuit that synchronizes the stimulus to the alternate phases of the line, but also introduces a random delay between zero and one-half the line period, thus reducing the fundamental and higher harmonics as well.

Digital filtering of on-line evoked potentials.

Evoked potentials recorded automatically at frequent intervals are a useful adjunct for monitoring head injury patients; however, unaveraged residual noise due to patient movement and synchronization of th- stimulus to harmonics of the line frequency is sometimes present. A frequency analysis was performed on 23 records with varying degrees of unaveraged noise and the results were used to design a digital filter. The frequency content of the records analyzed was largely contained in a band from D.

A computer system for neurosurgical patient monitoring.

The variables monitored in intensive care units are generally late indicators of neurologic deterioration. A system based on a LINC-8 computer was therefore developed for on-line monitoring of evoked potentials, electroencephalography (EEG), and transcranial and transthoracic impedances as well as conventional parameters. Somatosensory evoked potentials are recorded at either 30 min or 1 h intervals.

Peak-detection algorithm for EEG analysis.

A peak-detection method is described for computer analysis of the the electroencephalogramme (EEG). The technique consists of measuring the amplitude and time interval between successive maxima (peaks) and minima (troughs) in the signal. A critical feature of the peak-detection algorithm is the inclusion of an amplitude threshold criterion which eliminates the registration of low-voltage activity riding on EEG waves.

Early somatosensory evoked potentials.

The early somatosensory evoked potential secondary to median nerve stimulation in the human had an onset latency of 9--12 msec when recorded from scalp electrodes at vertex-to-mastoid, vertex-to-inion or at the base of the skull. Similar latencies were observed from responses recorded over the cervical dorsal columns during neurologic surgery. A latency difference of 1.

Mechanical and physiological effects of dentatotomy.

The role of the dentate ligaments in the pathogenesis of myelopathy secondary to disease conditions that alter the normal biomechanics of the spinal canal was studied in 14 dogs. The effects of posterior cord elevation on somatosensory evoked potentials (SSEP's) and tension requirements were compared before and after dentate ligaments section in acute experiments. At levels of posterior elevation usually within the confines of the canine canal, the dentate ligaments were the most significant element increasing tension requirements and SSEP alternations.

Computerized evaluation of electroencephalographic changes accompanying exchange transfusion in Reye's syndrome.

The EEGs of 7 children with Reye's syndrome (fatty liver and encephalopathy) were continuously recorded on magnetic tape for times ranging from 12 to 80 h. During these times the major therapy consisted of exchange blood transfusions. The tapes were automatically processed on a LINC-8 computer using a peak-detection algorithm.

Evaluation of electrode configurations in cerebellar implants.

Capacitively coupled currents of 100 Hz, 0.25 msec duration, were applied to multielectrode arrays implanted upon the superior and posterior surfaces of the chimpanzee cerebellum. The current required for 90% reduction in the amplitude of the evoked potential was inversely proportional to the number of electrodes upon the cerebellar surface.