Background The bispectral index (BIS), a value derived from the electroencephalograph (EEG), has been proposed as measure of anesthetic effect. To establish its utility for this purpose, it is important to determine relation among BIS, measured drug concentration, and increasing levels sedation. This study was designed evaluate four commonly used drugs: propofol, midazolam, isoflurane, alfentanil. Methods Seventy-two consenting volunteers were studied at institutions. Volunteers given either...

The free precession of an ensemble nuclear quadrupole moments in axial electric field gradient is studied by the pulsed induction method. A quantum-mechanical analysis describes and spin echo signals which result from application single double pulses radio-frequency at condition zero-field resonance. Beat modulation effects exhibited a small constant external magnetic are predicted analysis. An alternative semiclassical description given, analogous to macroscopic equations Bloch. Theory...

The amplitude of the nuclear induction signal is calculated for pulsed magnetic resonance experiments systems in which chemical exchange takes place between two sites different Larmor frequency. General expressions are given, within scope first order rate theory one and pulse as well multiple (Carr—Purcell) sequences. It proven that a Carr—Purcell sequence decay always expressible sum exponentials. time constants derived general case some special cases discussed detail. makes possible...

Proton magnetic resonance has been used to study water in Douglas fir and western red cedar. The free induction decay, when combined with a knowledge of chemical composition the wood, gives an accurate measure absolute moisture content. Spin-lattice relaxation was found be significantly different for two species. In sapwood, three distinct spin—spin times, T2, were measured assigned, help anatomical data, on cell wall, ray latewood tracheid lumens, earlywood lumens. This T2 behavior...

In Brief BACKGROUND: The perioperative course of patients undergoing intracranial surgery is frequently complicated by hypertensive episodes. Dexmedetomidine (DEX), an α-2 adrenoreceptor agonist, gaining popularity in neuroanesthesia, because its sympatholytic and antinociceptive properties may improve hemodynamic stability at critical moments surgery. We designed this study to assess the efficacy DEX controlling responses METHODS: Patients scheduled for elective craniotomy were randomly...

The authors describe a number of procedures necessary for the conduct multineuron experiment. They have identified three problem areas that are expected to be particularly noticeable as larger assemblies studied long periods under conditions where subject brain is engaged in behavioral or learning task. first concerns monitoring moving animal. It develop better multielectrode systems well appropriate manipulators high degree stability required. Multichannel amplification (perhaps...

The technique of deuterium magnetic resonance was used to study the orientational order perdeuterated acyl chains dimyristoylphosphatidylcholine (DMPC-d54) reconstituted with rhodopsin between 0 and 23 degrees C. This range includes gel liquid crystalline phase transition DMPC-d54 at 20 Molar lipid/protein (L/P) ratios L/P = infinity, 150, 50, 30, 12 were investigated. Measurements parameters showed that addition broadened for 150 50. No observed 30 12. Moment analysis spectral subtraction...

The shapes of NMR absorption lines, free induction decays, and Jeener echoes in systems such as lyotropic liquid crystals have been investigated theoretically experimentally. For a system having an axis symmetry for the molecular motion which makes angle ϑ with external magnetic field, secular part dipolar Hamiltonian 〈ℋd〉 (ϑ) is proportional to (1/2)(3 cos2ϑ−1). This leads characteristic logarithmic line shape nonoriented systems. experimental consequences are illustrated measurements on...

The theory of nuclear spin relaxation in gases and liquids developed by Bloom Oppenheim is used to interpret measurements lattice times for various gaseous systems over wide ranges temperature density. discussed include: molecular H2 with different ortho para concentrations; mixtures He, Ne, Ar, N2, CO2, O2, CO, NO, N2O; normal D2. analysis leads a determination the form anisotropic intermolecular potentials providing that isotropic part are known. Values quadrupole moments H2, N2O, D2...

GLASS, PETER S.; BLOOM, MARC; KEARSE, LEE; ROSOW, CARL; SEBEL, PETER; MANBERG, PAUL Author Information

Several studies suggest that relative changes in cerebral blood flow (CBF) may be assessed via transcranial Doppler sonography (TCD). The present study investigates the correlation between TCD-mean velocity (Vm) and CBF patients with a variety of types intracranial pathology undergoing cerebrovascular reactivity tests. After informed consent was obtained, 32 presenting stenoses brain-supplying arteries (n = 13), vascular malformations 6), surgical decompression for subarachnoid hemorrhage...