Radiative rates for E1, E2, M1, and M2 transitions in S-like to F-like tungsten ions (W LIX to W LXVI)

Calculations of energy levels, radiative rates and lifetimes are reported for eight ions of tungsten, i.e. S-like (W LIX) to F-like (W LXVI). A large number of levels have been considered for each ion and extensive configuration interaction has been included among a range of configurations. For the calculations, the general-purpose relativistic atomic structure package (. grasp) has been adopted, and radiative rates (as well as oscillator strengths and line strengths) are listed for all E1, E2, M1, and M2 transitions of the ions. Comparisons have been made with earlier available experimental and theoretical energies, although these are limited to only a few levels for most ions. Therefore for additional accuracy assessments, particularly for energy levels, analogous calculations have been performed with the flexible atomic code (. fac).

Radiative rates for E1, E2, M1, and M2 transitions in Br-like ions with 43≤Z≤50

Energies and lifetimes are reported for the eight Br-like ions with 43≤Z≤50, namely Tc IX, Ru X, Rh XI, Pd XII, Ag XIII, Cd XIV, In XV, and Sn XVI. Results are listed for the lowest 375 levels, which mostly belong to the 4s²4p⁵, 4s²4p⁴4ℓ, 4s4p⁶,4s²4p⁴5ℓ, 4s²4p³4d², 4s4p⁵4ℓ, and 4s4p⁵5ℓ configurations. Extensive configuration interaction among 39 configurations (generating 3990 levels) has been considered and the general-purpose relativistic atomic structure package (grasp) has been adopted for the calculations. Radiative rates are listed for all E1, E2, M1, and M2 transitions involving the lowest 375 levels. Previous experimental and theoretical energies are available for only a few levels of three, namely Ru X, Rh XI and Pd XII. Differences with the measured energies are up to 4% but the present results are an improvement (by up to 0.3 Ryd) in comparison to other recently reported theoretical data. Similarly for radiative rates and lifetimes, prior results are limited to those involving only 31 levels of the 4s²4p⁵, 4s²4p⁴4d, and 4s4p⁶ configurations for the last four ions. Moreover, there are generally no discrepancies with our results, although the larger calculations reported here differ by up to two orders of magnitude for a few transitions.

Radiative rates for E1, E2, M1, and M2 transitions in F-like ions with 37≤Z≤53

Calculations of energy levels, radiative rates and lifetimes are reported for 17 F-like ions with 37≤Z≤53. For brevity, results are only presented among the lowest 113 levels of the 2s²2p⁵, 2s2p⁶, 2s²2p⁴3ℓ, 2s2p⁵3ℓ, and 2p⁶3ℓ configurations, although the calculations have been performed for up to 501 levels in each ion. The general-purpose relativistic atomic structure package (grasp) has been adopted for the calculations, and radiative rates (along with oscillator strengths and line strengths) are listed for all E1, E2, M1, and M2 transitions of the ions. Comparisons are made with earlier available experimental and theoretical energies, although these are limited to only a few levels for most ions. Therefore for additional accuracy assessments, particularly for energy levels, analogous calculations have been performed with the Flexible Atomic Code (fac), for up to 72 259 levels. Limited previous results are available for radiative rates for comparison purposes, and no large discrepancy is observed for any transition and/or ion.

Benchmarking Energy Transitions: An Irish Case Study

The challenges of a low carbon energy transition have now been recognized by most nation states, each of whom have responded with differing visions, strategies and programmes, with variable veracity and effectiveness. Given the complexity of each country’s energy system (and sub-systems such as mobility, food etc), the differing sources and wealth of indigenous energy resources, the variable legacy of the fossil fuel regime and differing capacity to respond to global shifts in energy markets, it is clear that each country will respond to this challenge in very different ways.
This poses difficulties for understanding the extent to which a transition may be taking hold in any territory as simple indicators such as GHG emission data or increases in renewable energy ignore the complex contexts in which transitions take place. Drawing on the results of a study, funded by the Irish Environmental Protection Agency (Characterizing and Catalyzing Transitions) and using the wider theoretical framework of socio-technological transitions, this paper will explore the challenges, virtues and constraints of attempting to ‘benchmark’ the Republic of Ireland’s transition. This will lead to wider observations on the normative nature of benchmarking and a critical review of how we conceptualize the very idea of transition.

Transitions in Contentious Behaviour in Infancy and Later Aggressive Conduct Problems

Background. Individual trajectories toward aggression originate in early infancy, before there is intent to harm. We focused on infants who were contentious, i.e., prone to engage in anger and use of physical force with other people, and examined change in levels of contentiousness between 6 and 12 months of age with reference to later aggressive conduct problems.
Sample. The CCDS is a nationally representative sample of 321 firstborn children whose families were recruited from antenatal clinics in two National Health Service Trusts.
Method. Mothers, fathers, and a third family member or friend who knew infants well completed the Cardiff Infant Contentiousness Scale (CICS) at 6 months, which was stable form 6 to 12 months, and validated by direct observation of infants’ use of force against peers. Primary caregivers again completed the CICS at 12 months, and up to three informants completed the Child Behaviour Check List at mean ages of 36 and 84 months. We used Latent Transition Analysis to identify different groups of infants in respect to their patterns of contentiousness from 6 to 12 months.
Results
Three ordered classes of contentiousness from low to high were found at 6 and 12 months. Infants exposed to greater family adversity were more likely to move into the high-contentious class from 6 to 12 months. Higher contentiousness in infancy predicted more aggressive conduct problems at 33 months and thereafter.
Conclusions
Infants exposed to family adversity are already at disadvantage by 6 months and likely to escalate in their anger and aggressiveness over time.

Insight into the mechanism of galactokinase: role of a critical glutamate residue and helix/coil transitions

Galactokinase, the enzyme which catalyses the first committed step in the Leloir pathway, has attracted interest due to its potential as a biocatalyst and as a possible drug target in the treatment of type I galactosemia. The mechanism of the enzyme is not fully elucidated. Molecular dynamics (MD) simulations of galactokinase with the active site residues Arg-37 and Asp-186 altered predicted that two regions (residues 174-179 and 231-240) had different dynamics as a consequence. Interestingly, the same two regions were also affected by alterations in Arg-105, Glu-174 and Arg- 228. These three residues were identified as important in catalysis in previous computational studies on human galactokinase. Alteration of Arg-105 to methionine resulted in a modest reduction in activity with little change in stability. When Arg-228 was changed to methionine, the enzyme’s interaction with both ATP and galactose was affected. This variant was significantly less stable than the wild-type protein. Changing Glu-174 to glutamine (but not to aspartate) resulted in no detectable activity and a less stable enzyme. Overall, these combined in silico and in vitro studies demonstrate the importance of a negative charge at position 174 and highlight the critical role of the dynamics in to key regions of the protein. We postulate that these regions may be critical for mediating the enzyme’s structure and function. 

Étude exploratoire des transitions de milieux de vie en communauté des personnes présentant une déficience intellectuelle

Cette étude exploratoire dresse un portrait des transitions de milieux de vie (MDV) dans des Centres de réadaptation en déficience intellectuelle et en troubles envahissants du développement (CRDITED) de la grande région de Montréal. Elle permet d’identifier 1) les pratiques de transition de MDV des intervenants pivots en CRDITED, 2) les critères de succès de la transition de MDV et les moyens de les évaluer selon les personnes présentant une déficience intellectuelle et les intervenants pivots et 3) l’écart entre les pratiques souhaitées et les pratiques actuelles à partir du point de vue des deux types de participants. Des personnes présentant une déficience intellectuelle (N = 9) et des intervenants pivots (N = 19) se sont exprimés sur leurs expériences de transition de MDV en participant à des entretiens de groupe. Une analyse qualitative de contenu a permis d’identifier une typologie des expériences de transition de MDV du point de vue des intervenants pivots. Un seul type de transition de MDV parmi les cinq identifiés, le type préparée, offre des conditions favorisant la réalisation de la transition dans des conditions satisfaisantes pour les intervenants pivots. Les autres types de transitions (types dernière minute, explosive, clé en main et salle d’attente) offrent peu d’occasions pour la personne présentant une déficience intellectuelle de s’impliquer dans le processus de transition. Les propos des intervenants pivots permettent d’identifier les caractéristiques d’une transition de MDV qu’ils jugent idéale (type comme si c’était moi). Les types de transitions sont comparés entre eux sur deux axes, soit sur l’axe représentant un continuum d’implication de la personne présentant une déficience intellectuelle dans sa propre transition et sur l’axe identifiant les grandes étapes de réalisation de la transition. Les résultats permettent de déceler un écart important entre les transitions actuellement effectuées et les politiques, intentions et engagements de l’offre de service auprès de cette clientèle, notamment au regard de l’implication de la personne présentant une déficience intellectuelle dans les décisions relatives à sa transition de MDV. L’étude permet aussi d’identifier trois dimensions importantes de l’évaluation du succès de la transition selon les perspectives des personnes présentant une déficience intellectuelle et des intervenants pivots. Les dimensions identifiées sont : bien-être psychologique et comportement, santé physique et collaboration. Les propos des intervenants pivots permettent de constater qu’il existe parfois un paradoxe entre leurs perceptions du succès de la transition de MDV et celles des personnes présentant une déficience intellectuelle. L’interprétation des résultats a permis d’élaborer des recommandations afin de favoriser de meilleures pratiques de transition.

The economic crisis as a game changer? Exploring the role of social construction in sustainability transitions

Continuing economic turbulence has fuelled debates about social and political reform as much as it has stimulated actions and initiatives aimed at a more fundamental transition of dominant economic systems. This paper takes a transition perspective to explore, from a Western European viewpoint, how the economic crisis is actually viewed through a variety of interpretations and responded to through a range of practices. We argue that framing societal phenomena such as the economic crisis as "symptoms of transition" through alternative narratives and actions can give rise to the potential for (seemingly) short-term pressures to become game changers. Game changers are then defined as the combination of: specific events, the subsequent or parallel framing of events in systemic terms by engaged societal actors, and (eventually) the emergence of (diverse) alternative narratives and practices (in response to the systemic framing of events). Game changers, when understood in these terms, help to orient, legitimize, guide, and accelerate deep changes in society. We conclude that such dynamics in which game changers gain momentum might also come to play a critical role in transitions. Therefore, we argue for developing a better understanding of and methodologies to further study the coevolutionary dynamics associated with game changers, as well as exploring the implications for governance.

Self-Assembled InAs/GaAs Quantum Dot Solar Cells

Our work focuses on experimental and theoretical studies aimed at establishing a fundamental understanding of the principal electrical and optical processes governing the operation of quantum dot solar cells (QDSC) and their feasibility for the realization of intermediate band solar cell (IBSC). Uniform performance QD solar cells with high conversion efficiency have been fabricated using carefully calibrated process recipes as the basis of all reliable experimental characterization. The origin for the enhancement of the short circuit current density (Jsc) in QD solar cells was carefully investigated. External quantum efficiency (EQE) measurements were performed as a measure of the below bandgap distribution of transition states. In this work, we found that the incorporation of self-assembled quantum dots (QDs) interrupts the lattice periodicity and introduce a greatly broadened tailing density of states extending from the bandedge towards mid-gap. A below-bandgap density of states (DOS) model with an extended Urbach tail has been developed. In particular, the below-bandgap photocurrent generation has been attributed to transitions via confined energy states and background continuum tailing states. Photoluminescence measurement is used to measure the energy level of the lowest available state and the coupling effect between QD states and background tailing states because it results from a non-equilibrium process. A basic I-V measurement reveals a degradation of the open circuit voltage (Voc) of QD solar cells, which is related to a one sub-bandgap photon absorption process followed by a direct collection of the generated carriers by the external circuit. We have proposed a modified Shockley-Queisser (SQ) model that predicts the degradation of Voc compared with a reference bulk device. Whenever an energy state within the forbidden gap can facilitate additional absorption, it can facilitate recombination as well. If the recombination is non-radiative, it is detrimental to solar cell performance. We have also investigated the QD trapping effects as deep level energy states. Without an efficient carrier extraction pathway, the QDs can indeed function as mobile carriers traps. Since hole energy levels are mostly connected with hole collection under room temperature, the trapping effect is more severe for electrons. We have tried to electron-dope the QDs to exert a repulsive Coulomb force to help improve the carrier collection efficiency. We have experimentally observed a 30% improvement of Jsc for 4e/dot devices compared with 0e/dot devices. Electron-doping helps with better carrier collection efficiency, however, we have also measured a smaller transition probability from valance band to QD states as a direct manifestation of the Pauli Exclusion Principle. The non-linear performance is of particular interest. With the availability of laser with on-resonance and off-resonance excitation energy, we have explored the photocurrent enhancement by a sequential two-photon absorption (2PA) process via the intermediate states. For the first time, we are able to distinguish the nonlinearity effect by 1PA and 2PA process. The observed 2PA current under off-resonant and on-resonant excitation comes from a two-step transition via the tailing states instead of the QD states. However, given the existence of an extended Urbach tail and the small number of photons available for the intermediate states to conduction band transition, the experimental results suggest that with the current material system, the intensity requirement for an observable enhancement of photocurrent via a 2PA process is much higher than what is available from concentrated sun light. In order to realize the IBSC model, a matching transition strength needs to be achieved between valance band to QD states and QD states to conduction band. However, we have experimentally shown that only a negligible amount of signal can be observed at cryogenic temperature via the transition from QD states to conduction band under a broadband IR source excitation. Based on the understanding we have achieved, we found that the existence of the extended tailing density of states together with the large mismatch of the transition strength from VB to QD and from QD to CB, has systematically put into question the feasibility of the IBSC model with QDs.

410 - Phase transitions induced by coloured voltage noise in nerve membranes

Quantitative conditions are derived under which electrically excitable membranes can undergo a phase transition induced by an externally applied voltage noise. The results obtained for a non-cooperative and a cooperative form of the two-state model are compared. © 1981.

Phase Transitions in Engineered Ultracold Quantum Systems

The study of quantum degenerate gases has many applications in topics such as condensed matter dynamics, precision measurements and quantum phase transitions. We built an apparatus to create 87Rb Bose-Einstein condensates (BECs) and generated, via optical and magnetic interactions, novel quantum systems in which we studied the contained phase transitions. For our first experiment we quenched multi-spin component BECs from a miscible to dynamically unstable immiscible state. The transition rapidly drives any spin fluctuations with a coherent growth process driving the formation of numerous spin polarized domains. At much longer times these domains coarsen as the system approaches equilibrium. For our second experiment we explored the magnetic phases present in a spin-1 spin-orbit coupled BEC and the contained quantum phase transitions. We observed ferromagnetic and unpolarized phases which are stabilized by the spin-orbit coupling’s explicit locking between spin and motion. These two phases are separated by a critical curve containing both first-order and second-order transitions joined at a critical point. The narrow first-order transition gives rise to long-lived metastable states. For our third experiment we prepared independent BECs in a double-well potential, with an artificial magnetic field between the BECs. We transitioned to a single BEC by lowering the barrier while expanding the region of artificial field to cover the resulting single BEC. We compared the vortex distribution nucleated via conventional dynamics to those produced by our procedure, showing our dynamical process populates vortices much more rapidly and in larger number than conventional nucleation.

Intensive care survivors’ experiences of ward-based care: Meleis’ theory of nursing transitions and role development among critical care outreach services.

Aims and objectives. To explore the psychosocial needs of patients discharged from intensive care, the extent to which they are captured using existing theory on transitions in care and the potential role development of critical care outreach, follow-up and liaison services. Background. Intensive care patients are at an increased risk of adverse events, deterioration or death following ward transfer. Nurse-led critical care outreach, follow-up or liaison services have been adopted internationally to prevent these potentially avoidable sequelae. The need to provide patients with psychosocial support during the transition to ward-based care has also been identified, but the evidence base for role development is currently limited. Design and methods. Twenty participants were invited to discuss their experiences of ward-based care as part of a broader study on recovery following prolonged critical illness. Psychosocial distress was a prominent feature of their accounts, prompting secondary data analysis using Meleis et al.’s mid-range theory on experiencing transitions. Results. Participants described a sense of disconnection in relation to profound debilitation and dependency and were often distressed by a perceived lack of understanding, indifference or insensitivity among ward staff to their basic care needs. Negotiating the transition between dependence and independence was identified as a significant source of distress following ward transfer. Participants varied in the extent to which they were able to express their needs and negotiate recovery within professionally mediated boundaries. Conclusion. These data provide new insights into the putative origins of the psychosocial distress that patients experience following ward transfer. Relevance to clinical practice. Meleis et al.’s work has resonance in terms of explicating intensive care patients’ experiences of psychosocial distress throughout the transition to general ward–based care, such that the future role development of critical care outreach, follow-up and liaison services may be more theoretically informed.

Different Transitions towards Learning at University: Exploring the Heterogeneity of Motivational Processes

Transitions processes in higher education are characterized by new learning situations which pose challenges to most students. This chapter explores the heterogeneity of reactions to these challenges from a perspective of regulation processes. The Integrated Model of Learning and Action is used to identity different patterns of motivational regulation amongst students at university by using mixed distribution models. Six subpopulations of motivational regulation could be identified: students with self-determined, pragmatic, strategic, negative, anxious and insecure learning motivation. Findings about these patterns can be used to design didactic measures that will support students’ learning processes.