A note on elevated total gaseous mercury concentrations downwind from an agriculture field during tilling

Elevated mercury concentrations were measured at the University of Connecticut's mercury forest flux tower during spring agricultural field operations on an adjacent corn field. Concentrations at the tower were elevated, a peak of 7.03 ng m(-3) over the background concentration of 1.74+/-0.26 ng m(-3), during times when the prevailing wind was from the direction of the corn field and during periods when the soil was disturbed by tilling. Strong deposition to the forest was recorded at the point of measurement when atmospheric mercury concentrations were elevated. The strongest deposition rate was a 1 hour maximum of -4011 ng m(-2) h(-1) following the initial peak in atmospheric concentrations, Analyses of the meteorological conditions and mercury content in agricultural soil, manure and the diesel consumed in the tilling operation indicate that the source of the mercury was from the agricultural tilling operations and it was advected over the tower enriching the atmospheric concentrations above the forest canopy leading to deposition. These results indicate that agriculture operations resulting in a disturbed soil surface may be a source of atmospheric mercury originating from the pool of mercury bound in the soil. This represents a previously undocumented source of mercury emissions resulting from anthropogenic activities.     

Modal Operators for Coequations

We present the dual to Birkhoff's variety theorem in terms of predicates over the carrier of a cofree coalgebra. We then discuss the dual to Birkhoff's completeness theorem, showing how closure under deductive rules dualizes to yield two modal operators acting on coequations. We discuss the properties of these operators and show that they commute, and we prove the invariance theorem, which is the formal dual of the completeness theorem.     

Superload Evaluation of the Bonnet Carré Spillway Bridge

The passage of overloads that require special permitting is a common occurrence. Prior to the passage of such an overload, a simplified computer analysis is generally conducted to predict the expected behavior of the bridge. This paper addresses the field evaluation of three superloads that crossed the Bonnet Carré Spillway Bridge in Louisiana. Emphasis is placed on comparisons between the expected and actual behavior due to rotational restraint, live load distribution, the stiffening effect of bridge rails, and other factors. Finite-element modeling was conducted and the approach taken along with the results obtained are described. One important conclusion was that the longitudinal configuration of the axle loads supplied by the hauler was configured differently than indicated on the permit. While the gross load was accurate, the distribution between sets of axles varied considerably from those assumed in the permitting process. To minimize the potential for damage to bridges it is therefore recommended that axle loads be weighed prior to the passage of such overloads.     

A New Experimental Design to Study the Kinetics of Solid Dissolution into Liquids at Elevated Temperature

Metallurgical and Materials Transactions B - A new method was developed to study the dissolution of a solid cylinder in a liquid under forced convection at elevated temperature. In the new design,...     

Speaking rate from proximal and distal contexts is used during word segmentation.

A series of eye-tracking and categorization experiments investigated the use of speaking-rate information in the segmentation of Dutch ambiguous-word sequences. Juncture phonemes with ambiguous durations (e.g., [s] in 'eens (s)peer,' “once (s)pear,” [t] in 'nooit (t)rap,' “never staircase/quick”) were perceived as longer and hence more often as word-initial when following a fast than a slow context sentence. Listeners used speaking-rate information as soon as it became available. Rate information from a context proximal to the juncture phoneme and from a more distal context was used during on-line word recognition, as reflected in listeners' eye movements. Stronger effects of distal context, however, were observed in the categorization task, which measures the off-line results of the word-recognition process. In categorization, the amount of rate context had the greatest influence on the use of rate information, but in eye tracking, the rate information's proximal location was the most important. These findings constrain accounts of how speaking rate modulates the interpretation of durational cues during word recognition by suggesting that rate estimates are used to evaluate upcoming phonetic information continuously during prelexical speech processing. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Spatial memory during progressive disorientation.

Human spatial representations of object locations in a room-sized environment were probed for evidence that the object locations were encoded relative not just to the observer (egocentrically) but also to each other (allocentrically). Participants learned the locations of 4 objects and then were blindfolded and either (a) underwent a succession of 70° and 200° whole-body rotations or (b) were fully disoriented and then underwent a similar sequence of 70° and 200° rotations. After each rotation, participants pointed to the objects without vision. Analyses of the pointing errors suggest that as participants lost orientation, represented object directions generally "drifted" off of their true directions as an ensemble, not in random, unrelated directions. This is interpreted as evidence that object-to-object (allocentric) relationships play a large part in the human spatial updating system. However, there was also some evidence that represented object directions occasionally drifted off of their true directions independently of one another, suggesting a lack of allocentric influence. Implications regarding the interplay of egocentric and allocentric information are considered. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Diameter-Controlled Synthesis of Polyaniline Nanofibers

Summary  Various diameters of polyaniline (PANI) nanofibers were easily made by varying the sweep rate in the electrochemical polymerization of the aniline monomer. At a sweep rate of 5 mV/s, the PANI nanofibers have an average diameter of 450 nm with a median of 440 nm. The fibers are short, on the order of a few microns in length, and exhibit a branched geometry. Increasing the sweep rate to 50 mV/s produced longer nanofibers with a smaller average diameter of 200 nm. Nanofibers synthesized at 100 mV/s were noted to be smaller with an average and median diameter of 100 nm. These results illustrate the ease in which the morphology of nanostructured PANI can be altered and indicate that the method has the potential to create multi-diameter fibers or mixed-morphology materials.     

Immediate-startle stimulus presentation fails to condition freezing responses to contextual cues.

Placed 28 male Wistar rats in a novel and distinctive environment. 18 of these received an intense startle-eliciting white noise stimulus. Animals that experienced a 60-sec delay between placement and the startle stimulus demonstrated significant freezing in the context, both poststartle (Session 1) and on a later startle-free test (Session 2). Animals that received immediate startle, however, did not differ on either occasion from animals that did not experience the startle stimulus. The amplitude of the startle response was not affected by this manipulation, which indicates a dissociation between freezing and startle responses with immediate- vs delay-startle presentation. The findings are consistent with M. S. Fanselow's (1986) conditioned stimulus (CS)-based associative explanation of the immediate-shock freezing deficit. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Surface analysis of disbonded titanium/sol-gel/polyimide joints

Disbonded lap-shear specimens were analyzed to determine the locus of failure within bonded titanium (Ti) sol-gel polyimide joints. Bonded Ti alloys are being evaluated for use at an operating temperature of 175 °C. Determining the locus of failure for bonded Ti lap-shear specimens is part of a larger effort to develop durable, environmentally safe surface treatments for Ti alloys. Surface-treated Ti alloy (Ti-6Al-4V) plates are bonded in a standard lap-shear specimen configuration and exposed to temperature for specified intervals. The lap-shear bond joint consists of two etched Ti panels coated with a silicon and zirconium containing sol-gel, primed with a polyimide, and then bonded together with adhesive and supporting scrim material. The lap-shear specimens are tested for overall strength and failure modes. Specimens with adhesive failure modes were examined with x-ray photoelectron spectroscopy (XPS) to determine the composition of the bond joint failure layer. Analysis shows that the failure was located closer to the sol-gel/polyimide interface than to the Ti/sol-gel interface. Transmission electron micrographs (TEM) of the cross-sectioned joint confirmed the chemical distribution determined from the XPS data.