Altered electrodermal responsivity associated with clinical pain

We used certain physiologic maneuvers to perturb the autonomic nervous system (ANS) in an attempt to detect a link between the ANS and pain. In the unperturbed state, we found no difference in the electrodermal response among normal controls, preoperative patients (increased stress without pain) and postoperative patients (increased stress and pain). The electrodermal response elicited by autonomic maneuvers was significantly attenuated in postoperative patients but not in preoperative patients or in normal control subjects.     

Energy Transfer in Molecular Collisions

Computational studies of energy transfer in models of molecular collisions are presented and analyzed qualitatively and semi-quantitatively. Particular attention is given to those approximations where the leading term is already in good qualitative agreement with the exact numerical results. In particular, results for the distorted wave approximation in an adiabatic basis are reported and compared with the exact results. It is argued that for slow molecular collisions, the efficiency of the transfer is determined by the “Franck Condon” overlap near the repulsive part of the intermolecular potential.     

The aging behavior of orthorhombic marten site in Ti-6-2-4-6

In Ti-6-2-4-6 alloys, beta transforms to orthorhombic martensite when quenched from a temperature of 1188 or above, X-ray analysis showed that aging at 773 or 873 gradually reduces the degree of orthorhombicity until a hexagonal structure equivalent to alpha, but having the morphological characteristics of the prior martensite, is produced. The orthorhombicity is reduced by solute rejection to beta which forms as particles both homogeneously and heterogeneously within the martensitic structure. The structure at maximum hardness is a fine distribution of Burger’s oriented beta particles in a matrix of martensite of greatly reduced orthorhombicity. Overaging appears to occur as a result of coarsening of the homogeneous beta particles. It is shown that aging at temperatures from 873 to 1083 K results in growth of one particular varient of the beta which is located at the interface between twin related regions composing a martensite lath. This beta along with similarly oriented beta at lath interfaces forms a continuous beta matrix by a gradual growth process. It is shown that this matrix has the identical orientation and shape of the original beta grain prior to quenching. A mechanism is proposed to account for this “memory effect”.     

Response of graywater recycling systems based on hydroponic plant growth to three classes of surfactants

Anionic (sodium laureth sulfate, SLES), amphoteric (cocamidopropyl betaine, CAPB) and nonionic (alcohol polyethoxylate, AE) surfactants were added to separate nutrient film technique (NFT) hydroponic systems containing dwarf wheat (Triticum aestivum cv. USU Apogee) in a series of 21 day trials. Surfactant was added either in a (1). temporally dynamic mode (1-3 g surfactant m(-2) growing area d(-1)) as effected by automatic addition of a 300 ppm surfactant solution to meet plant water demand, or (2). continuous mode (2 g surfactant m(-2) growing area d(-1)) as effected by slow addition (10 mLh(-1)) of a 2000 ppm surfactant solution beginning at 4d after planting. SLES showed rapid primary degradation in both experiments, with no accumulation 24 h after initial addition. CAPB and AE were degraded less rapidly, with 30-50% remaining 24 h after initial addition, but CAPB and AE levels were below detection limit for the remainder of the study. No reductions in vegetative growth of wheat were observed in response to SLES, but biomass was reduced 20-25% with CAPB and AE. Microbial communities associated with both the plant roots and wetted hardware surfaces actively degraded the surfactants, as determined by monitoring surfactant levels following pulse additions at day 20 (with plants) and day 21 (after plant removal). In order to test whether the biofilm communities could ameliorate phytotoxicity by providing a microbial community acclimated for CAPB and AE decay, the continuous exposure systems were planted with wheat seeds after crop removal at day 21. Acclimation resulted in faster primary degradation (>90% within 24h) and reduced phytotoxicity. Overall, the studies indicate that relatively small areas (3-5m(2)) of hydroponic plant systems can process per capita production of mixed surfactants (5-10 g x person(-1)d(-1)) with minimal effects on plant growth.     

Structural relationships between measures based on heart beat intervals: potential for improved risk assessment

Decreased left ventricular ejection fraction is the most commonly used risk factor for identification of patients at high-risk for lethal ventricular arrhythmic events. Twenty-four-hour electrocardiographic (ECG) approaches to risk stratification include: counts of ventricular premature contractions (VPCs), measures of heart rate variability (HRV), and heart rate turbulence (HRT) which has two components, turbulence onset and turbulence slope (TS). Refinement of these ECG risk stratifiers could enhance their clinical utility. We explored the structural relationships between heart rate (HR) and HRV and HRT measures. Our goal was to separate out the component of these measures due to the underlying average heart rate (HR), thus potentially reducing the variability of the measures and increasing their power to stratify risk. We proposed re-scaling tachograms of heart-beat intervals so that the re-scaled tachogram has a HR of 75 (or equivalently an average interval of 800 ms) and calculating HRV and HRT from the rescaled time series. We also explored the relationship between the number of VPCs and HRT. We showed that TS is structurally related to the number of VPCs (and hence to the length of the ECG recording). We proposed an adjusted TS that is independent of the number of VPCs. We also addressed the ability of shorter ECG recording to estimate HRV and HRT measures. We evaluated standard and rescaled HRV and HRT measures using qualifying ambulatory ECG recordings from 744 patients in the Cardiac Arrhythmia Suppression Trial. We found that measures based on the rescaled tachogram had reduced variance (20% to 40%). Correlations between measures were also substantially reduced. We also found substantial circadian effects on some, but not all HRV indices, not explained by the circadian pattern in HR and possibly pointing to additional measures for risk prediction. In conclusion, we found that adjusting for HR and the number of VPCs in heart-beat related ambulatory ECG measures has the potential to significantly improve the power of these measures to risk stratify cardiac patients.     

Waveband selection for determination of nitrate in soil using mid-infrared attenuated total reflectance spectroscopy

This paper investigates the possibility of determining nitrate concentration in soil pastes using spectral absorbance at several fixed wavebands. A three-step procedure for determining the most appropriate wavebands, as well as their width, is described. This procedure is applied to a dataset that includes eleven soils with various nitrate concentrations ranging from 0 to approximately 150 mg [N]/kg [dry soil]. The results show that nitrate concentration can be determined quite acceptably using only four 12 cm(-1) wide wavebands, centered at 1280, 1330, 1379, and 1430 cm(-1). The prediction errors range from approximately 1.5 to 14.0 mg [N]/kg [dry soil], depending on soil composition and moisture content, with the lighter and more vulnerable (pollution-wise) soils having errors inferior to 10 mg [N]/kg [dry soil]. These results are similar to results obtained by applying partial least square to the 'continuous' spectrum, and indicate that the development of a soil nitrate attenuated total reflectance (ATR) sensor based on a few fixed mid-infrared (MIR) wavebands could be considered.     

The feasibility of producing laser plasmas via photoionization

The production of uniform large-volume laser plasmas with electron-ion densities on the order of 10¹²/cm³or larger by means of photoionization is investigated. An externally applied electric field heats the electron gas to the optimal temperature for excitation of laser levels. Photoionization by intense UV light may take place in a low partial pressure gas of low ionization potential species dispersed throughout the host laser medium, or the laser medium itself may serve as the photoionized species. Both single-photon ionization and two-photon two-step ionization are shown to be applicable.     

Telemetered heart rate and skin potential of a chronic schizophrenic patient especially during periods of hallucinations and periods of talking.

Took telemetric recordings of a male 23-yr-old chronic schizophrenic patient's heart rate and skin potential while on the ward. During periods of hallucinations, the skin potential increased significantly, while there were no changes in heart rate. Neither heart rate nor skin potential increased during periods of talking. When very angry, heart rate showed a substantial deceleration followed by a large increase. There was no change in skin potential during the period of anger. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Predictability, control, and the pituitary-adrenal response in rats.

Compared the effects of signaled and unsignaled shock on the pituitary-adrenal response of 68 male Long-Evans hooded rats. In Exp I, exposure to the 2 procedures yielded no difference in plasma corticosterone levels. In Exp II, the addition of a food-reinforced leverpressing baseline produced conditioned suppression in the signaled condition but no group difference in steroid values. To guard against steroid elevations produced by exposure to shock, blood samples in Exp III were obtained during brief test sessions prior to the occurrence of shock. The procedure resulted in a significant elevation in the steroid levels of the signaled shock group. In Exp IV, a within-Ss sampling procedure revealed that disparate group steroid values obtained earlier in the session had converged by the end of the test session. The final experiment produced the original failure to obtain a steroid difference due to predictability in the absence of a behavioral baseline. Results suggest that (a) the effects of predictability are largely seen in the temporal pattern of steroid elevations and not in their terminal values, (b) the effects of predictability on steroids are modulated by the availability of control, and (c) control is not confined to the stimulus that is being predicted. (36 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)