Gas Phase Hydrolysis and Oxo-Exchange of Actinide Dioxide Cations: Elucidating Intrinsic Chemistry from Protactinium to Einsteinium.

Gas-phase bimolecular reactions of metal cations with water provide insights into intrinsic characteristics of hydrolysis. For the actinide dioxide cations, actinyl(V) AnO2 + , melding of experiment and computation provides insights into trends for hydrolysis, as well as for oxo-exchange between actinyls and water that proceeds by a hydrolysis pathway. Here this line of inquiry is further extended into the actinide series with CCSD(T) computations of potential energy surfaces, for the reaction pathway for oxo-exchange through hydrolysis of nine actinyl(V) ions, from PaO2 + to EsO2 + . The computed surfaces are in accord with previous experimental results for oxo-exchange, and furthermore predict spontaneous exchange for CmO2 + , BkO2 + , CfO2 + and EsO2 + , but not for AmO2 + . Natural Bond Order analysis of the species involved in both hydrolysis and oxo-exchange reveals an inverse correlation between the barrier to hydrolysis and the charge on the actinide centre, q(An). Based on this correlation, it can be concluded that hydrolysis, and related phenomena such as oxo-exchange, become less favourable as the charge on the metal centre decreases. The new results provide a straightforward rationalization of trends across a wide swathe of the actinide series

System characterization of a magnetically suspended flywheel

The purpose of flywheel energy storage is to provide a means to save energy during times when the satellite is in sunlight, and then return the energy during the time when the satellite is in darkness. Typically, an energy storage device operates cyclically, where for satellites in Low Earth Orbit (LEO) the typical period is 60 minutes of sunlight followed by 30 minutes of darkness. If a lifetime of 17 years is required the energy storage system must be capable of sustaining approximately 100,000 cycles. The recent developments at the University of Maryland and how these progressions apply to a 500 Watt-hour magnetically suspended flywheel stack energy storage system are covered. The work includes hardware testing results from a stack flywheel energy storage system, improvements in the area of non-contacting displacement transducers, and performance enhancements of magnetic bearings. The experimental results show that a stack flywheel energy storage system is a feasible technology

Activation of Water by Pentavalent Actinide Dioxide Cations: Characteristic Curium Revealed by a Reactivity Turn after Americium.

Swapping of an oxygen atom of water with that of a pentavalent actinide dioxide cation, AnO2+ also called an "actinyl", requires activation of an An-O bond. It was previously found that such oxo exchange in the gas phase occurs for the first two actinyls, PaO2+ and UO2+, but not the next two, NpO2+ and PuO2+. The An-O bond dissociation energies (BDEs) decrease from PaO2+ to PuO2+, such that the observation of a parallel decrease in the An-O bond reactivity is intriguing. To elucidate oxo exchange, we here extend experimental studies to AmO2+, americyl(V), and CmO2+, curyl(V), which were produced in remarkable abundance by electrospray ionization of Am3+ and Cm3+ solutions. Like other AnO2+, americyl(V) and curyl(V) adsorb up to four H2O molecules to form tetrahydrates AnO2(H2O)4+ with the actinide hexacoordinated by oxygen atoms. It was found that AmO2+ does not oxo-exchange, whereas CmO2+ does, establishing a "turn" to increasing the reactivity from americyl to curyl, which validates computational predictions. Because oxo exchange occurs via conversion of an actinyl(V) hydrate, AnO2(H2O)+, to an actinide(V) hydroxide, AnO(OH)2+, it reflects the propensity for actinyl(V) hydrolysis: PaO2+ hydrolyzes and oxo-exchanges most easily, despite the fact that it has the highest BDE of all AnO2+. A reexamination of the computational results for actinyl(V) oxo exchange reveals distinctive properties and chemistry of curyl(V) species, particularly CmO(OH)2+

Contextual bias and insulation against bias during aesthetic rating. The roles of VMPFC and DLPFC in neural valuation

The scientific study of aesthetic experience through the examination of the neural correlates of sensory and motor responses works of art and to other visual images has thrived during the last decade. The neural substrate of embodied responses to works of art, and to visual images more generally, has been the object of much attention. This research, however, has tended to sidestep the question of aesthetic preference and rating, and the neural correlates of contextual influences on such ratings. Responses in the domain of perception–action coupling have provided useful and important evidence for the role of somatic and emotional responses in viewers’ engagement with works of art. Nevertheless, the degree to which they form the basis of evaluation, ranking, and even judgment remains unclear. In this chapter we concentrate on the respective roles of the ventromedial prefrontal cortex (VMPFC) and the dorsolateral prefrontal cortex (DLPFC) during aesthetic evaluation, particularly the aesthetic evaluation of visual works of art. Activity in these areas is modulated by external contextual pressures on viewing. The roles of ACC, hippocampal and striatal connections in the process of rating and evaluating works of visual art, and the relationship between expert and non-expert responses, are also discussed

Practice architectures and sustainable curriculum renewal

While there are numerous pedagogical innovations and varying forms of professional learning to support change, teachers rarely move beyond the initial implementation of new ideas and policies and few innovations reach the institutionalised stage. Building on both site ontologies and situated learning in communities of practice perspectives, this paper explores the theory of practice architectures to offer a different and legitimate perspective on sustainable curriculum renewal. Specifically, a practice architecture either enables or constrains particular practice and constitutes the construction of practice from semantic (e.g. language), social (e.g. power relations), and physical (e.g. materials) spaces. Through the juxtaposition of practice architectures with an empirical illustration of longer-term pedagogical change, the paper argues that for pedagogical change to be sustained a practice architecture that relates to an innovation’s intended learning outcomes and the contexts in which an innovation can be used needs to be created. Consequently, the theory of practice architectures can guide reform programmes. Curricularists can begin programmes with a pre-planned approach to assist, a) teachers’ understanding of how to use an innovation, and b) the deconstruction and reconstruction of practice architectures to support an innovation’s survival

Cascaded Photoenhancement: Implications for Photonic Chemical and Biological Sensors

Our analysis shows that coupling of gold nanoparticles to microspheres will evoke a cascading effect from the respective photoenhancement mechanisms. We refer to this amplification process as cascaded photoenhancement, and the resulting cavity amplification of surface-enhanced Raman scattering (SERS) and fluorescence as CASERS and CAF, respectively. Calculations, based on modal analysis of scattering and absorption by compound spheres, presented herein indicate that the absorption cross sections of metal nanoparticles immobilized onto dielectric microspheres can be greatly enhanced by cavity resonances in the microspheres without significant degradation of the resonators. Gain factors associated with CSP of 10(exp 3) - 10(exp 4) are predicted for realistic experimental conditions using homogenous microspheres. Cascaded surface photoenhancement thus has the potential of dramatically increasing the sensitivities of fluorescence and vibrational spectroscopies

Plyler Children: 21st Century Challenges with Judicial-Policy Implementation Affecting Immigrant Children in New Jersey

Denying unauthorized immigrant children access to a free public education through incomplete judicial policy implementation may lead to an illiterate underclass. Communicating, implementing, and enforcing Plyler v. Doe school registration documentation requirements continue to be difficult at the district level. In 2008, an ACLU study in New Jersey found that 187 of 516 school districts were mandating inappropriate documentation from parents registering their children. Separation of powers requires that executive agencies proactively implement transformative judicial decisions

Missed medical appointments during shifts to and from daylight saving time

Transitions into and out of Daylight Saving Time (DST) can provide insights into how a minor change to a regular sleep–wake cycle can inadvertently affect health. We examined the relationship between DST and missed medical appointments. Using a large dataset, the proportion of missed appointments were examined prior and post spring and autumn clock changes. As predicted, the number of missed medical appointments significantly increased following the spring (forward) clock change and the week of the clock change. This trend was reversed following the transition out of DST. The implications of scheduling appointments around DST to increase attendance are discussed

Ecological separation of small cathartid vultures in South America

During three field seasons, totalling 20 months between 1984-87, the ecological separation of four species of small Cathartid vultures was investigated at Hato Masaguaral in the flat savannas or Llanos of central Venezuela, South America. The focus of the study was an analysis of the role of migrant Turkey Vultures Cathartes aura meridionalis, in the scagenging guild of resident vultures, particularly in relation to a resident subspecies of Turkey Vulture C. a. ruficollis. Ecological separation between different taxa was achieved by differential habitat use by foraging vultures, feeding on different types of carcases and at different times. Where mixed-species flocks fed at carrion, social dominance mediated competition; heavier taxa were not necessarily dominant. During the dry season, migrant Turkey, Lesser Yellow-headed Cathartes burrovianus and Black Vultures Coragyps atratus foraged at highest densities in open savanna habitats. By contrast, resident Turkey and King Vultures Sarcor amphus papa foraged almost entirely in closed gallery forest. In the wet season, the numbers of Cathartes vultures declined by 6 fold in the absence of migrant Turkey Vultures which returned to North America. There was a distinct habitat shift in resident Turkey Vultures at the end of the dry season from gallery forest to open savanna habitats; conversely at the end of the wet season birds moved back into the gallery forest. Some residents may themselves have been migratory, moving into the ranch area at the end of the dry season, but this did not explain the decrease of Cathartes vulture density between seasons. The changes coincided with the departure of the majority of migrants in the spring and with the influx of migrants in the autumn, respectively. The core areas used by radiotragged resident Turkey Vultures shifted seasonally from gallery forest to open savanna. Most marked migrant Turkey Vultures were not resighted, suggesting that they passed through the study area on their way further south or that they had large home ranges. Compared to migrant Turkey Vultures a larger proportion of resident Turkey and Black Vultures were resighted. Comparative observations at bait sites in gallery forest and open savanna showed that carcases were detected more quickly, group sizes of migrant Turkey Vultures were greater, and agonistic encounter rates were higher in the open. Both migrant and resident Turkey Vultures occurred at similar densities over the forest but most carcases were first located by residents. Migrants won almost all agonistic encounters initiated against resident Turkey Vultures. The feeding rate of resident Turkey Vultures was significantly and negatively affected by the numbers of migrant Turkey and King Vultures, but not by other residents present at carcases. While the body condition of migrant Turkey Vultures was low after autumn migration from North America, the condition of birds trapped in subsequent months improved. However, the body condition of residents was below average throughout the dry season when migrants were present. By contrast, in the wet season when migrants were absent, the body condition of residents was above average. The wing-loading of different taxa was related to their foraging strategies; low wing-loading enabled some taxa (e.g. resident Turkey Vultures) to fly at low altitude over vegetation and forage using olfaction. Others, with higher wing-loading depended on sight for foraging (directly by observing carcases in the open or by watching the activities of other vultures) and on thermals to remain aloft (e.g. Black Vultures). Results suggested that, although there may be seasonal changes in food supply which may explain wet season changes in foraging behaviour, resident Turkey Vultures were forced to forage in gallery forest during the dry season to reduce interference competition from migrants

Effects of Timber Harvesting and Plantation Development on Cavity-nesting Birds in New Brunswick

We studied the abundance of cavity-nesting birds in forestry-related habitats in a region of Acadian forest in New Brunswick. We examined five reference stands of natural forest, a chronosequence of conifer plantations up to 19 years old (the oldest in the study area), two selectively harvested stands, and a 30-year-old naturally regenerated clear-cut. The species richness and abundance of cavity-nesting birds were higher in reference forest (average 10.0 species per stand; 5.3 territories per 10 ha) than in plantations (2.3/stand; 1.0/10 ha), selectively harvested stands (7.0/stand; 3.8/10 ha), or the naturally regenerated clear-cut (5.0/stand; 2.5/10 ha). A cluster analysis segregated the “community” of cavity-nesting birds of natural forest from those of other treatments. Of the various harvested stands and plantations, five with a relatively large number of residual snags clustered similarly in the cluster analysis, while those with no or very few snags also clustered together. We used arrays of nest boxes (12 per stand) to examine whether the availability of cavities was limiting the use of habitats otherwise suitable for foraging by cavity-dependent species. Nest-box use for nesting and roosting was much higher in the seven plantations examined (average 4.0/10 ha for nesting and 2.9/10 ha for roosting) than in three reference stands (each 0.3/10 ha), suggesting that the plantations were deficient in this critical-habitat element. Our results suggest that certain mitigations, such as leaving residual snags and living cavity-trees, would help maintain populations of some cavity-dependent birds in clear-cuts and plantations. However, some cavity-dependent species might not be accommodated by these mitigations and are potentially at risk in intensively managed areas, unless landscape-scale management plans ensure the survival of sufficient areas of older mixed-wood forest