Extracellular recordings from patterned neuronal networks using planar microelectrode arrays

Neuronal cell networks have been reconstructed on planar microelectrode arrays (MEAs) from dissociated hippocampal pyramidal neurons. Microcontact printing (microCP) and a photoresist-liftoff method were used to selectively localize poly-L-lysine (PLL) on the surface of MEAs. Haptotaxis led to the organization of the neurons into networks localized adjacent to microelectrodes. Various grids of PLL with 2-25-microm-wide lines spaced by 50-200 microm with 15-25-microm nodes at intersection points were used to guide cell body attachment and neurite outgrowth. Bursting activity with spike amplitude attenuation was observed, and multichannel recordings detected instances of coincident firing activity. Finally, we present here an extracellular recording from a approximately 2 microm bundle of guided neurites.     

Microstructure coarsening during static annealing of 60Sn40Pb solder joints: II eutectic coarsening kinetics

The eutectic coarsening kinetics for 60Sn40Pb solder joints annealed at 50°C to 150° C was determined to be of the form

The effects of a lack of social recognition on online communication behavior

Online services and applications extend the influencing opportunities of traditional word-of mouth (WOM). Unlike traditional word-of-mouth, the online environment allows for special features such as anonymity in user-generated content. Furthermore, the personality of online users affects their motivation when creating this content. The aim of this paper is to link specific online activities, i.e., the posting of product ratings and participation in discussions in online forums, with certain personality traits within an empirical study. The findings, based on an online survey with more than 16,900 completed questionnaires, indicate that opinion leaders in the online environment cannot be compared with traditional opinion leaders in terms of their articulation and personality structure. In regard to online activities with a high influencing potential, the results of moderated regression analyses show that persons with an introverted personality are more active as online opinion leaders due to the lack of social recognition they experience. The results have implications for how marketers should present incentive structures to address and integrate potential online opinion leaders, and how scholars should understand the role of opinion leaders in the online environment.     

Examining infants' preferences for tempo in lullabies and playsongs.

Caregivers around the world sing to their infants. Infants not only prefer to listen to infant-directed singing over adult-directed singing, but infant-directed singing also serves a function, communicating affective information to preverbal infants to aid in adjusting arousal levels. Pitch variation has previously been identified as one performance feature that may help to convey the message. Earlier research has indicated that infants' pitch preferences are context dependent, suggesting that infants are tuned in to the communicative intent of infant-directed singing. However, there are several other performance-based features present in infant-directed singing that may also contribute to the affective message. The current study examined the role of context on infants' tempo preferences in sung playsongs and lullabies. Using a head-turn preference procedure, we measured 24 preverbal infants' natural preferences for foreign language playsongs and lullabies as a function of tempo. Infants showed a preference for fast over slow tempo playsongs, but no such context dependent preference was found within lullabies. Results partially support the role of tempo as a communicative feature of infant directed singing. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

On the rate-controlling mechanism during the plastic deformation of nanocrystalline Cu

Data in the literature on the effect of grain size from micrometers to nanometers on the flow stress, dislocation density, apparent activation volume and strain rate sensitivity parameters for Cu are analyzed to determine the rate-controlling mechanism. Accord occurs for the intersection of dislocations over the entire grain size range from 10 nm to 150 μm. The dislocation density and its structure and the related Friedel factor are important parameters.     

Electrosintering of iron powder compacts

The influence of a nominal external electric field E=3 to 10 kV/cm on the sintering of iron powder compacts for 30 minutes at 1140 °C in a vacuum of ∼10⁻⁶ torr was investigated. It was found that the field reduced the porosity by as much as 29 to 73 pct compared to sintering without a field, the magnitude depending on the procedure employed to measure the density of the specimen. Optical microscopy revealed that the specimen electrosintered with E=10 kV/cm had a skin of ∼0.2 mm in thickness, where the porosity was significantly less than in the interior. This was also the depth of carburization that was obtained upon carburizing the electrosintered specimens. It is proposed that the decrease in porosity produced by the field results from a decrease in the chemical potential of vacancies at or just below the charged external surface. Vacancy flux equations employed to calculate the porosity as a function of distance below the external surface showed that the porosity becomes approximately zero at a distance of x _c=0.4 to 0.5 mm below the surface, which is in reasonable accord with the microscopy measurements. Similar values of x _c were obtained by assuming that the entire porosity decrease given by the density measurements occurred in a ring of thickness of x _c below the external surface. The difference in the density measured by two Archimedes-principle procedures and microscopy observations suggests that the cavities open to the external surface of the electrosintered specimens are smaller or narrower than those for specimens sintered without a field.     

Shaping cocaine abstinence by successive approximation.

Cocaine-using methadone-maintenance patients were randomized to standard contingency management (abstinence group, n?=?49) or to a contingency designed to increase contact with reinforcers (shaping group, n?=?46). For 8 weeks, both groups earned escalating-value vouchers based on thrice-weekly urinalyses: The abstinence group earned vouchers for cocaine-negative urines only; the shaping group earned vouchers for each urine specimen with a 25% or more decrease in cocaine metabolite (first 3 weeks) and then for negative urines only (last 5 weeks). Cocaine use was lower in the shaping group, but only in the last 5 weeks, when the response requirement was identical. Thus, the shaping contingency appeared to better prepare patients for abstinence. A 2nd phase of the study showed that abstinence induced by escalating-value vouchers can be maintained by a nonescalating schedule, suggesting that contingency management can be practical as a maintenance treatment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of prepartum selenium treatment on uterine involution in the dairy cow

Selenium injections and oral vitamin E supplementation prepartum were related to: postpartum uterine involution (decrease in uterine size per unit time) and days to minimum uterine size in a 2 X 2 factorial design. Complete data were analyzed from 64 cows. Groups were selenium plus vitamin E, vitamin E, selenium, and control. Factors significantly affecting uterine size between 14 and 50 d postpartum were cow weight, days postpartum-linear, days postpartum-quadratic, day X metritis, and day X metritis X selenium treatment. Days to minimum uterine size were significantly less in cows with metritis and selenium treated when compared with cows with metritis and not selenium treated (32.9 vs. 35.8).     

Retardation of grain growth and cavitation by an electric field during superplastic deformation of ultrafine-grained 3Y-TZP at 1,450–1,600 °C

The influence of a continuous dc electric field applied orthogonal to the tensile direction on the flow stress, grain growth, and cavitation during superplastic deformation (SPD) of ultrafine-grained 3Y-TZP at 1,450–1,600 °C was determined. The field gave a significant reduction in the level of the stress-strain curve, and reduced grain growth and cavitation. The decrease in flow stress by the field was attributed mainly to the retardation of grain growth. The decrease in cavitation correlated with the retardation of grain growth and was attributed largely to the reduction in flow stress by the field.     

Modeling Studies on the Development of a System for Real-Time Magnetic-Field Imaging of Steel Reinforcing Bars Embedded Within Reinforced Concrete

This paper addresses fundamental issues associated with the development of a real-time magnetic-field imaging system for nondestructive testing of prestressed and reinforced concrete. Modeling results have shown that with a square coil of 300 times300 times2.5 mm³, 10-mm rebars can be imaged down to a depth of 100 mm. Studies also indicate that the vertical component of the induced magnetic field is most favorable as it can readily be reconstructed to yield geometry and dimensional information pertaining to the rebar structure.