A quartet of fermionic expressions for M(k,2k±1)M(k,2k\pm1) Virasoro characters via half-lattice paths

We derive new fermionic expressions for the characters of the Virasoro minimal models $M(k,2k\pm1)$ by analysing the recently introduced half-lattice paths. These fermionic expressions display a quasiparticle formulation characteristic of the $\phi_{2,1}$ and $\phi_{1,5}$ integrable perturbations. We find that they arise by imposing a simple restriction on the RSOS quasiparticle states of the unitary models $M(p,p+1)$. In fact, four fermionic expressions are obtained for each generating function of half-lattice paths of finite length $L$, and these lead to four distinct expressions for most characters $\chi^{k,2k\pm1}_{r,s}$. These are direct analogues of Melzer's expressions for $M(p,p+1)$, and their proof entails revisiting, reworking and refining a proof of Melzer's identities which used combinatorial transforms on lattice paths. We also derive a bosonic version of the generating functions of length $L$ half-lattice paths, this expression being notable in that it involves $q$-trinomial coefficients. Taking the $L\to\infty$ limit shows that the generating functions for infinite length half-lattice paths are indeed the Virasoro characters $\chi^{k,2k\pm1}_{r,s}$.Comment: 29 pages. v2: minor improvements, references adde

Integrable Supersymmetry Breaking Perturbations of N=1,2 Superconformal Minimal Models

We display a new integrable perturbation for both N=1 and N=2 superconformal minimal models. These perturbations break supersymmetry explicitly. Their existence was expected on the basis of the classification of integrable perturbations of conformal field theories in terms of distinct classical KdV type hierarchies sharing a common second Hamiltonian structure.Comment: 10 pages (harvmac), LAVAL PHY-20-9

Half-lattice paths and Virasoro characters

We first briefly review the role of lattice paths in the derivation of fermionic expressions for the M(p,p') minimal model characters of the Virasoro Lie algebra. We then focus on the recently introduced half-lattice paths for the M(p,2p+/-1) characters, reformulating them in such a way that the two cases may be treated uniformly. That the generating functions of these half-lattice paths are indeed M(p,2p+/-1) characters is proved by describing weight preserving bijections between them and the corresponding RSOS lattice paths. Here, the M(p,2p-1) case is derived for the first time. We then apply the methods of Bressoud and Warnaar to these half-lattice paths to derive fermionic expressions for the Virasoro characters X^{p,2p+/-1}_{1,2} that differ from those obtained from the RSOS paths. This work is an extension of that presented by the third author at the "7th International Conference on Lattice Path Combinatorics and Applications", Siena, Italy, July 2010.Comment: 22 page

Effects of Fragmentation on Post-Inflationary Reheating

We consider the effects of fragmentation on the post-inflationary epoch of reheating. In simple single field models of inflation, an inflaton condensate undergoes an oscillatory phase once inflationary expansion ends. The equation of state of the condensate depends on the shape of the scalar potential, $V(\phi)$, about its minimum. Assuming $V(\phi) \sim \phi^k$, the equation of state parameter is given by $w = P_\phi/\rho_\phi = (k-2)/(k+2)$. The evolution of condensate and the reheating process depend on $k$. For $k \ge 4$, inflaton self-interactions may lead to the fragmentation of the condensate and alter the reheating process. Indeed, these self-interactions lead to the production of a massless gas of inflaton particles as $w$ relaxes to 1/3. If reheating occurs before fragmentation, the effects of fragmentation are harmless. We find, however, that the effects of fragmentation depend sensitively to the specific reheating process. Reheating through the decays to fermions is largely excluded since perturbative couplings would imply that fragmentation occurs before reheating and in fact could prevent reheating from completion. Reheating through the decays to boson is relatively unaffected by fragmentation and reheating through scatterings results in a lower reheating temperature.Comment: 31 pages, 10 figures; v2 matches version published in JCA

Experimental observation of the proportional effect hypothesis of the kinematic theory : preliminary report

For more than ten years, the Kinematic Theory has been exploited successfully in applications dealing with handwriting processing. The theory uses Delta-Lognormal profiles to model the behaviors of the motor control and the neuromuscular system involved in the production of rapid movements. Its main underlying assumption is that the cumulative time delays of the propagated impulse responses, recorded along different points on a neuromuscular system are linked by proportional relationships. The study reported in this paper aims at using the physiological knowledge of the upper arm to deeply investigate this assumption. First, the concept of a subsystem is clarified and justified. Then, to observe the proportionality hypothesis, surface electromyographic signals (SEMG) recorded from the upper limb, during the execution of rapid handwriting movements, are analyzed. The results reveal proportional regressions, with strong correlation, between the cumulative time delays of the muscle activities, calculated from SEMG envelopes. This finding highlights the relationships that exist between the macro-delays observed on the SEMG bursts and constitutes an observation proof of the proportionality hypothesis. These developments add further support to the usefulness of the Kinematic Theory as a tool for the study and understanding of human movement

A heteroleptic diradical Cr(iii) complex with extended spin delocalization and large intramolecular magnetic exchange

Successive chemical reductions of the heteroleptic complex [(tpy)Cr III(tphz)] 3+(tpy = terpyridine; tphz = tetrapyridophenazine) give rise to the mono- and di-radical redox isomers, [(tpy)Cr III(tphz? -)] 2+and [(tpy? -)Cr III(tphz? -)] +, respectively. As designed, the optimized overlap of the involved magnetic orbitals leads to extremely strong magnetic interactions between theS= 3/2 metal ion andS= 1/2 radical spins, affording well isolatedS T= 1 andS T= 1/2 ground states at room temperature. </p

Using Redox-Active πbridging Ligand as a Control Switch of Intramolecular Magnetic Interactions

Intramolecular magnetic interactions in the dinuclear complexes [(tpy)­Ni­(tphz)­Ni­(tpy)]^<i>n</i>+ (<i>n</i> = 4, 3, and 2; tpy, terpyridine; tphz, tetrapyridophenazine) were tailored by changing the oxidation state of the pyrazine-based bridging ligand. While its neutral form mediates a weak antiferromagnetic (AF) coupling between the two <i>S</i> = 1 Ni­(II), its reduced form, tphz^•–, promotes a remarkably large ferromagnetic exchange of +214(5) K with Ni­(II) spins. Reducing twice the bridging ligand affords weak Ni–Ni interactions, in marked contrast to the Co­(II) analogue. Those experimental results, supported by a careful examination of the involved orbitals, provide a clear understanding of the factors which govern strength and sign of the magnetic exchange through an aromatic bridging ligand, a prerequisite for the rational design of strongly coupled molecular systems and high <i>T</i>_C molecule-based magnets

Measuring organizational readiness for knowledge translation in chronic care

<p>Abstract</p> <p>Background</p> <p>Knowledge translation (KT) is an imperative in order to implement research-based and contextualized practices that can answer the numerous challenges of complex health problems. The Chronic Care Model (CCM) provides a conceptual framework to guide the implementation process in chronic care. Yet, organizations aiming to improve chronic care require an adequate level of organizational readiness (OR) for KT. Available instruments on organizational readiness for change (ORC) have shown limited validity, and are not tailored or adapted to specific phases of the knowledge-to-action (KTA) process. We aim to develop an evidence-based, comprehensive, and valid instrument to measure OR for KT in healthcare. The OR for KT instrument will be based on core concepts retrieved from existing literature and validated by a Delphi study. We will specifically test the instrument in chronic care that is of an increasing importance for the health system.</p> <p>Methods</p> <p>Phase one: We will conduct a systematic review of the theories and instruments assessing ORC in healthcare. The retained theoretical information will be synthesized in a conceptual map. A bibliography and database of ORC instruments will be prepared after appraisal of their psychometric properties according to the standards for educational and psychological testing. An online Delphi study will be carried out among decision makers and knowledge users across Canada to assess the importance of these concepts and measures at different steps in the KTA process in chronic care.</p> <p>Phase two: A final OR for KT instrument will be developed and validated both in French and in English and tested in chronic disease management to measure OR for KT regarding the adoption of comprehensive, patient-centered, and system-based CCMs.</p> <p>Discussion</p> <p>This study provides a comprehensive synthesis of current knowledge on explanatory models and instruments assessing OR for KT. Moreover, this project aims to create more consensus on the theoretical underpinnings and the instrumentation of OR for KT in chronic care. The final product--a comprehensive and valid OR for KT instrument--will provide the chronic care settings with an instrument to assess their readiness to implement evidence-based chronic care.</p

All-optical trion generation in single walled carbon nanotubes

We present evidence of all optical trion generation and emission in undoped single walled carbon nanotubes (SWCNTs). Luminescence spectra, recorded on individual SWCNTs over a large CW excitation intensity range, show trion emission peaks red-shifted with respect to the bright exciton peak. Clear chirality dependence is observed for 22 separate SWCNT species, allowing for determination of electron-hole exchange interaction and trion binding energy contributions. Luminescence data together with ultrafast pump probe experiments on chirality sorted bulk samples suggest that exciton-exciton annihilation processes generate dissociated carriers that allow for trion creation upon a subsequent photon absorption event.Comment: 13 pages, 4 figure

Une occupation de la fin du Dernier Maximum Glaciaire dans les Pyrénées : le Magdalénien inférieur de la grotte des Scilles (Lespugue, Haute-Garonne)

International audienceThe excavations by R. and S. Saint-Périer at the Grotte des Scilles (Lespugue, Haute-Garonne, France) in 1923-1924 yielded archaeological material attributed to the Magdalenian. The re-examination of this old collection now allows a more precise characterization of it, in light of recent research on this period. This article presents the different artefact types found (lithic and osseous tools, faunal remains, personal ornaments, portable art items and one sandstone lamp) in order to consider all activities documented at the site. Particular attention is given to typological and technological data, the analyses of which point to a Lower Magdalenian chronological attribution. A SMA 14C date shows that occupation took place around 16,000 years BP (19,400 years cal BP) at the Grotte des Scilles. The identification, for the first time, of a Lower Magdalenian presence in the Pyrenees raises new questions concerning Magdalenian occupation at the end of the Last Glacial Maximum in southwestern France and northern Spain.Les fouilles menées par R. et S. Saint-Périer dans les années 1920 à la grotte des Scilles (Lespugue, Haute-Garonne) ont livré un ensemble de vestiges attribués au Magdalénien. L'étude de cette collection ancienne offre désormais la possibilité de préciser cette caractérisation à la lumière de travaux récents sur cette période. La présentation des différentes catégories de vestiges (industries lithique et osseuse, faune, parure, art mobilier et lampe) permet d'appréhender l'ensemble des registres d'activités documentés sur le site. En particulier, cet article présente les éléments typo-technologiques qui fournissent des arguments pour rattacher l'occupation de cette cavité au Magdalénien inférieur. Une date 14C par SMA situe cette période autour de 16 000 BP (19 400 cal BP) à la grotte des Scilles. La mise en évidence de ce premier jalon pyrénéen conduit ensuite les auteurs à discuter du peuplement magdalénien à la fin du dernier maximum glaciaire dans le sud-ouest de la France et le nord de l'Espagne