Restoration process of the need for autonomy: The early alarm stage.

Autonomy is described by self-determination theory as a basic psychological need, essential for individuals' well-being. While basic needs are generally thought to induce a restorative response when thwarted, evidence for such a process is lacking for autonomy. To date, most evidence indicates that autonomy deprivation leads to disaffection of this need in favor of other motives. A temporal model based on the general adaptation syndrome was adapted to reconcile this seeming contradiction. Specifically, it is hypothesized that an early alarm response aimed at restoring the satisfaction of the need for autonomy should precede the later relinquishment and compensation of this need that would result from a prolonged deprivation. Three studies provide support for this model by showing the existence of the immediate autonomy restorative response. Using a controlling situation to manipulate autonomy deprivation, the authors demonstrate in Experiments 1 and 2 that a controlling context leads to enhanced accessibility and an approach bias for autonomy-related stimuli. Experiment 3 indicates that the urge to restore autonomy can also affect personal judgment, leading individuals to make more independent judgments, exercising a nonreactive form of autonomy. Integration of this model within self-determination theory is discussed. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Ultrasonic trapping of microparticles in suspension and reaction monitoring using Raman microspectroscopy

An ultrasonic standing wave around 2 MHz has been used for trapping and concentration of suspended micrometer-size particles in a flow cell, whereas Raman microspectroscopy was used as a nondestructive technique to provide molecular information about the trapped particles. With this approach, detection and discrimination of different polymer microparticles based on their characteristic Raman spectra was performed. Dextran, poly(vinyl alcohol), and melamine resin-based beads, with and without functionalization, were used for this purpose. Furthermore, taking advantage of the flow-through characteristics of the cell and the versatility of the employed flow system, full control over the media surrounding the trapped particles was achieved. This allowed us to perform chemical reactions on the trapped particles and to monitor spectral changes in real time. Here retention of cation-exchanger beads loaded with silver ions and subsequent reduction of the silver ions was demonstrated. In this way, surface-enhanced Raman (SER) active beads were prepared and retained in the focus of the Raman microscope by means of the ultrasonic field. Injection of analytes in the flow system thus allowed recording of their SER spectra. Using 9-aminoacridine, a linear dependence of the found SER signal in the range from 1 to 10 microM has been achieved. The repeatability in the recorded SER intensities was on the order of 4-5%. This included bead retention, surface-enhanced Raman layer synthesis, and analyte detection.     

Experimental and numerical investigations regarding laser drop on demand jetting of Cu alloys

Active noise reduction, structural health monitoring and energy harvesting are possible applications of active structure components. An integration of piezoceramic modules into casted Al-structures can be defined as a long term goal to achieve high functional integration and thus to address lightweight construction. Since the liquidus temperature of standard electronic solder is not sufficient to withstand the thermal loads during Al die casting processes, a suitable wire bonding process is an enabling technology to generate active Al structures. In the scope of this work, a laser based drop on demand joining process is introduced. The process consists of four main steps. First a spherical CuSn12 braze preform of 600 µm diameter with a liquidus temperature of 1233 K is inserted into a ceramic capillary and being molten by a laser pulse. The droplet is subsequently ejected by gas overpressure and impinges on the joining area, consisting of the electrode structure of the piezo element and the Cu wire, where it forms a firm joint of the Cu wire and the electrode structure. In order to evaluate time–temperature profiles of the capillary during melting and detachment of the braze preform a simulation model was set up, indicating heating and cooling rates of 22,100 K/s. Further, the impact of the capillary geometry on the velocity fields of a passing medium was evaluated. By changing the capillary geometry, the gas flow velocity could be reduced by about 10% according to the simulation model, which resulted in a reduction of droplet height deviation of 7.5% and a reduction of the droplet diameter deviation of 32.2% in the experiment.     

Mercapto-pyridines and mercapto-pyrimidines as urease inhibitors

Several mechanisms of urease hydrolysis of urea have been proposed. Major advances in this area were made when it was recognized that nickel played an important role in the hydrolysis of urea. Two recent literature reports indicate that dipyridyls can be used to complex with nickel. In both of these reports, the dipyridyl was used as a ligand for stabilizing an intermediate nickel(II) complex. In addition, it is known that heterocyclic mercapto compounds inhibit urease through the formation of disulfide bonds. Because of the stability of these complexes, compounds with similar structures were examined as potential urease inhibitors. From our initial tests it was not clear which functional group of these multifunctional compounds was responsible for the inhibition or whether it was necessary to retain the disulfide linkage for other potential inhibitors in this class. Therefore, a series of mercapto-pyridines, a series of mercapto-pyrimidines, and pyridine-N-oxide itself were tested for their urease inhibitory characteristics. It appears that the key functional group responsible for the inhibition is the mercapto group itself, with the N-oxide function adding little to the urease inhibitory power in the monomeric compounds. It is suspected that the presence of the N-oxide moiety in the dimeric compounds results in increases in solubility and a weakening of the strength of the disulfide bond, thus producing a more active inhibitor.     

Evolutionarily stable sets in quantum penny flip games

In game theory, an Evolutionarily Stable Set (ES set) is a set of Nash Equilibrium (NE) strategies that give the same payoffs. Similar to an Evolutionarily Stable Strategy (ES strategy), an ES set is also a strict NE. This work investigates the evolutionary stability of classical and quantum strategies in the quantum penny flip games. In particular, we developed an evolutionary game theory model to conduct a series of simulations where a population of mixed classical strategies from the ES set of the game were invaded by quantum strategies. We found that when only one of the two players’ mixed classical strategies were invaded, the results were different. In one case, due to the interference phenomenon of superposition, quantum strategies provided more payoff, hence successfully replaced the mixed classical strategies in the ES set. In the other case, the mixed classical strategies were able to sustain the invasion of quantum strategies and remained in the ES set. Moreover, when both players’ mixed classical strategies were invaded by quantum strategies, a new quantum ES set was emerged. The strategies in the quantum ES set give both players payoff 0, which is the same as the payoff of the strategies in the mixed classical ES set of this game.     

High temperature surface effects of He implantation in ICF fusion first wall materials

The first wall armor of the inertial confinement fusion reactor chambers must withstand high temperatures and significant radiation damage from target debris and neutrons. The resilience of multiple materials to one component of the target debris has been investigated using energetic (20-40 keV) helium ions generated in the inertial electrostatic confinement device at the University of Wisconsin. The materials studied include: single-crystalline, and polycrystalline tungsten, tungsten-coated tantalum-carbide ‘foams’, tungsten-rhenium alloy, silicon carbide, carbon-carbon velvet, and tungsten-coated carbon-carbon velvet. Steady-state irradiation temperatures ranged from 750 to 1250 °C with helium fluences between 5 × 10¹⁷ and 1 × 10²⁰ He⁺/cm². The crystalline, rhenium alloyed, carbide foam, and powder metallurgical tungsten specimens each experienced extensive pore formation after He⁺ irradiation. Flaking and pore formation occurred on silicon carbide samples. Individual fibers of carbon-carbon velvet specimens sustained erosion and corrugation, in addition to the roughening and rupturing of tungsten coatings after helium ion implantation.