Fimbria-fornix cut affects spontaneous activity, two-way avoidance and delayed non matching to sample, but not latent inhibition

Latent inhibition (LI) consists of a decrement in conditioning to a stimulus as a result of its prior nonreinforced preexposure. Based on evidence pointing to the involvement of the hippocampus and the nucleus accumbens (NAC) in LI disruption, it has been proposed that LI depends on the integrity of the subicular input to the NAC. Since fibers originating in the subiculum and destined for the NAC run through the fimbria-fornix, we assessed the effects of fimbria-fornix lesion, made using a knife cut, on LI. In addition, we assessed the effects of the fimbria-fornix cut in three tests known to be sensitive to lesions to the hippocampal region, namely, spontaneous activity, two-way active avoidance and delayed-non-matching-to-sample. In accord with previously documented effects of lesions to the hippocampus and related structures, the fimbria-fornix cut increased spontaneous activity (Experiment 1), facilitated the acquisition of two-way active avoidance (Experiment 3), and produced a delay-dependent deficit in the delayed-non-match-to-sample task (Experiment 4), demonstrating that it disrupted hippocampal functioning. In contrast, LI remained unaffected by the fimbria-fornix cut (Experiment 2), indicating that disruption of subicular input to the NAC is not responsible for the attenuation of LI following non-selective hippocampal lesions. The implications of these results for the neural circuitry of LI are discussed.     

An empirical analysis of the computerization of interactive software evaluation systems

This research studies factor analysis of traditional survey- questionnaires for interactive software evaluation in order to construct a Principal Factor Conversion Function (PFCF). Such a PFCF may be used in several ways: first, for exploratory purposes, to discover the principal factors of the traditional questionnaire; second to test the potential of data reduction within significant loss of information; and third to compare the traditional manual evaluation to a condensed computerized interactive software evaluation. A CAI system was used as the software to be evaluated in this research.     

Behavior-change trials to assess the feasibility of improving complementary feeding practices and micronutrient intake of infants in rural Bangladesh

This study used simple rapid-assessment techniques to test the feasibility of increasing the consumption of complementary foods by infants by asking mothers to increase meal quantity or frequency or by altering the viscosity/energy density of the food. The feasibility of using micronutrient supplements either added directly to food or administered as liquid drops was also examined. The study was conducted in rural Bangladesh and involved four separate short-term behavioral change trials. Depending on the trial, fieldworkers recruited 30 to 45 infants 6 to 12 months of age. Following recommendations to increase the amount of food provided to infants, the mean intakes from single meals increased from 40 +/- 23 g on day 1 to 64 +/- 30 g on day 7 (p < 0.05). In a second trial, the mean meal frequency increased from 2.2 +/- 1.3 on day 1 to 4.1 +/- 1.3 on day 7 (p < 0.05). Provision of high-energy-density diets, prepared by decreasing viscosity with alpha-amylase or by hand-mashing rice and dhal into a paste before feeding, increased single-meal energy consumption from 54 +/- 35 kcal to 79 +/- 52 kcal or 75 +/- 37 kcal (p < 0.05), respectively. Both types of micronutrient supplements were well accepted and used according to recommendations. In conclusion, it was possible to change short-term child-feeding behaviors to promote increased food intake, mealfrequency, energy density, and micronutrient consumption. Because each of these interventions lasted for only about 1 week, however, the long-term sustainability of these changes is not known. Moreover, the effect of increased feeding of complementary foods on intakes of breastmilk and total daily consumption of energy and nutrients requires further study.     

Poly(amidoamine) dendrimers as nanoscale diffusion probes in sol-gel films investigated by total internal reflection fluorescence spectroscopy

Three generations of poly(amidoamine) dendrimers were dye-labeled and chemically modified to have terminal carboxyl groups and used as variably sized probes to study diffusion in thin sol-gel films. Total internal reflection fluorescence spectroscopy experiments, both correlation and concentration-jump measurements, were employed to measure the relative populations and effective diffusion coefficients of dendrimers in the films. For films prepared from small (27-nm) silica particles, larger dendrimers could be completely excluded from penetrating the sol-gel structure. In films made of larger (150-nm) particles with correspondingly larger pores, concentration-jump experiments showed that larger dendrimers are excluded from more of the intraparticle pore space than small dendrimers. Similarly, fluorescence-correlation measurements showed that the diffusion of smaller dendrimers exhibited greater tortuosity than larger dendrimers in the interparticle pores of the film. The smaller dendrimers explore a greater volume of smaller, more convoluted pores, whereas larger dendrimers penetrate a smaller volume of larger, more open pores.     

In-line optical fiber sensors based on cladded multimode tapered fibers

The use of uniform-waist cladded multimode tapered optical fibers is demonstrated for evanescent wave spectroscopy and sensors. The tapering is a simple, low-loss process and consists of stretching the fiber while it is being heated with an oscillating flame torch. As examples, a refractive-index sensor and a hydrogen sensor are demonstrated by use of a conventional graded-index multimode optical fiber. Also, absorbance spectra are measured while the tapers are immersed in an absorbing liquid. It is found experimentally that the uniform waist is the part of the taper that contributes most to the sensor sensitivity. The taper waist diameter may also be used to adjust the sensor dynamic range.     

Assessing changes in the meaning of children's behavior: Factorial invariance of teachers' temperament ratings.

Tested the assumption that the same behavioral rating scale may be used over a wide age range, using temperament ratings provided by 24 teachers of 564 kindergarten through 4th-grade children. A LISREL analysis supported the hypothesized 3-factor model and established factorial invariance. The consistency of the factor structure over grade and the similarity of this structure to the findings from other factor analytic studies suggest that teachers may organize information about student behavior along the same dimensions regardless of the grade they teach. Such invariance may result from the demands of the teaching task rather than actual covariation among student behaviors. (40 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influence of aeration on hydrophobic organic contaminant distribution and diffusive flux in estuarine sediments

Dredging operations, resuspension events during storms, and bioturbation alter the oxic state of estuarine sediments and induce changes in the composition of dissolved and particle-associated natural organic matter. These changes may alter the distribution of hydrophobic organic chemicals (HOCs) in sediments and their diffusive flux across the sediment-water interface. In this study, the impact of aerating anoxic sediments on the distribution and diffusive flux of a model HOC, 2,2',4,4'-tetrachlorobiphenyl (TeCB), was investigated. Anoxic estuarine sediments collected from three sites along a salinity gradient were used to determine site-specific apparent sorption coefficients for porewater dissolved organic carbon (Kpwdoc) and sediment organic carbon (Koc) under anoxic and oxic conditions. A two-compartment sediment flux model was employed to examine the diffusive flux of TeCB under both oxic states. Aeration of anoxic porewaters resulted in significant decreases in porewater dissolved organic matter (DOMpw) aromaticity as indicated by declines in molar absorptivity at 254 nm (p < 0.005). Aeration also resulted in a 9-13% decrease in DOMpw concentration (p < 0.005) at the two sites exhibiting lower ionic strengths; the high ionic strength site did not exhibit a significant change in DOMpw concentration (p > 0.10). The impact of aeration on TeCB distribution and diffusive flux appeared to be site-specific. Aeration of anoxic sediments induced a significant 1.4 log unit reduction in Kpwdoc at the lowest ionic strength site (p < 0.0005), while sediments from the intermediate ionic strength site exhibited a significant 0.6 log unit increase (p < 0.005). No significant change in sorption to DOMpw was observed for the high ionic strength site (p > 0.10). The sediment displaying the drop in Kpwdoc also exhibited a significant 0.4 log unit drop in Koc (p < 0.01), while the other two sites did not exhibit significant aeration-induced changes in sorption to particle-associated organic matter (p > 0.10). No significant change in diffusive flux was observed for two sites (p > 0.10), while a significant 89-110 mg m(-2) yr(-1) increase in diffusive flux was observed at the low ionic strength site (p < 0.10). This latter result represented approximately a doubling in diffusive flux. In the systems studied, facilitation of TeCB transport across the sediment-water interface by organic colloids did not appear important.     

Monitoring the formation and decay of transient photosensitized intermediates using pump-probe UV resonance Raman spectroscopy. I: Self-modeling curve resolution

Resolution of transient excited-state Raman scattering from ground-state and solvent bands is a challenging spectroscopic measurement since excited-state spectral features are often of low intensity, overlapping the dominant ground-state and solvent bands. The Raman spectra of these intermediates can be resolved, however, by acquiring time-resolved data and using multidimensional data analysis methods. In the absence of a physical model describing the kinetic behavior of a reaction, resolution of the pure-component spectra from these data can be accomplished using self-modeling curve resolution, a factor analysis technique that relies on the correlation in the data along a changing composition dimension to resolve the component spectra. A two-laser UV pump-probe resonance-enhanced Raman instrument was utilized to monitor the kinetics of amine quenching of excited-triplet states of benzophenone. The formation and decay of transient intermediates were monitored over time, from 15 ns to 100 micros. Factor analysis of the time-resolved spectral data identified three significant components in the data. The time-resolved intensities at each Raman wavenumber shift were projected onto the three significant eigenvectors, and least-squares criteria were developed to find the common plane in the space of the eigenvectors that includes the observed data. Within that plane, the three pure-component spectra were resolved using geometric criteria of convex hull analysis. The resolved spectra were found to arise from benzophenone excited-triplet states, diphenylketyl radicals, and the solvent and ground-state benzophenone.     

Influence of the storage orientation on the aerodynamic particle size of a suspension metered dose inhaler containing propellant HFA-227

Presented in this work are the results of a study designed to investigate the impact of the storage position on the particle size distribution (PSD) of a steroid suspension metered dose inhaler (MDI) containing propellant HFA-227. It was hypothesized that the orientation of MDI samples upon storage could influence the PSD of the emitted dose, since it determines the amount of contact the liquid formulation has with the valve and therefore the quantity of nonvolatile leachable materials from the valve components that may enter the product and potentially impact the aerosol spray dynamics. Samples stored in the valve down orientation (i.e., complete contact of the liquid formulation with the valve) showed a higher level of leachables compared to those samples stored valve up (i.e., minimal contact of the formulation with the valve). The valve down samples were found to produce larger particles in the emitted aerosol spray using both cascade impaction, the preferred method of regulatory submission, as well as laser diffraction. It was postulated that the larger particle size of the inverted samples was attributed to its higher levels of leachables. Based on our findings, it is recommended that in order to set appropriate controls on the product PSD, the storage orientation of the product will need to be considered.     

A practical approach to fire hazard analysis for offshore structures

Offshore quantitative risk assessments (QRA) have historically been complex and costly. For large offshore design projects, the level of detail required for a QRA is often not available until well into the detailed design phase of the project. In these cases, the QRA may be unable to provide timely hazard understanding. As a result, the risk reduction measures identified often come too late to allow for cost effective changes to be implemented. This forces project management to make a number of difficult or costly decisions. This paper demonstrates how a scenario-based approached to fire risk assessment can be effectively applied early in a project's development. The scenario or design basis fire approach calculates the consequence of a select number of credible fire scenarios, determines the potential impact on the platform process equipment, structural members, egress routes, safety systems, and determines the effectiveness of potential options for mitigation. The early provision of hazard data allows the project team to select an optimum design that is safe and will meet corporate or regulatory risk criteria later in the project cycle. The focus of this paper is on the application of the scenario-based approach to gas jet fires. This paper draws on recent experience in the Gulf of Mexico (GOM) and other areas to outline an approach to fire hazard analysis and fire hazard management for deep-water structures. The methods presented will include discussions from the recent June 2002 International Workshop for Fire Loading and Response.