Field-Induced Quantum Criticality of Systems with Ferromagnetically Coupled Structural Spin Units

The field-induced quantum criticality of compounds with ferromagnetically coupled structural spin units (as dimers and ladders) is explored by applying Wilson's renormalization group framework to an appropriate effective action. We determine the low-temperature phase boundary and the behavior of relevant quantities decreasing the temperature with the applied magnetic field fixed at its quantum critical point value. In this context, a plausible interpretation of some recent experimental results is also suggested.Comment: to be published in Physics Letters

Phase Diagram of the Heisenberg Spin Ladder with Ring Exchange

We investigate the phase diagram of a generalized spin-1/2 quantum antiferromagnet on a ladder with rung, leg, diagonal, and ring-exchange interactions. We consider the exactly soluble models associated with the problem, obtain the exact ground states which exist for certain parameter regimes, and apply a variety of perturbative techniques in the regime of strong ring-exchange coupling. By combining these approaches with considerations related to the discrete Z_4 symmetry of the model, we present the complete phase diagram.Comment: 17 pages, 10 figure

Flux Phase as a Dynamic Jahn-Teller Phase: Berryonic Matter in the Cuprates?

There is considerable evidence for some form of charge ordering on the hole-doped stripes in the cuprates, mainly associated with the low-temperature tetragonal phase, but with some evidence for either charge density waves or a flux phase, which is a form of dynamic charge-density wave. These three states form a pseudospin triplet, demonstrating a close connection with the E X e dynamic Jahn-Teller effect, suggesting that the cuprates constitute a form of Berryonic matter. This in turn suggests a new model for the dynamic Jahn-Teller effect as a form of flux phase. A simple model of the Cu-O bond stretching phonons allows an estimate of electron-phonon coupling for these modes, explaining why the half breathing mode softens so much more than the full oxygen breathing mode. The anomalous properties of $O^{2-}$ provide a coupling (correlated hopping) which acts to stabilize density wave phases.Comment: Major Revisions: includes comparisons with specific cuprate phonon modes, 16 eps figures, revte

Evaluating synergy between marbofloxacin and gentamicin in Pseudomonas aeruginosa strains isolated from dogs with otitis externa

The aim of this study was to determine antimicrobial susceptibility of Pseudomonas aeruginosa strains to marbofloxacin and gentamicin, and investigate the possible synergistic, additive, indifferent or antagonistic effects between the two agents. P. aeruginosa strains can develop resistance quickly against certain antibiotics if used alone, thus the need emerges to find synergistic combinations. A total of 68 P. aeruginosa strains isolated from dogs were examined. In order to describe interactions between marbofloxacin and gentamicin the checkerboard microdilution method was utilized. The MICs (minimum inhibitory concentrations) for marbofloxacin and gentamicin were in the range 0.25–64 mg/L and 0.25–32 mg/L, respectively. The combination of marbofloxacin and gentamicin was more effective with a MIC range of 0.031–8 mg/L and a MIC90 of 1 mg/L, compared to 16 mg/L for marbofloxacin alone and 8 mg/L for gentamicin alone. The FIC (fractional inhibitory concentration) indices ranged from 0.0945 (pronounced synergy) to 1.0625 (indifference). Synergy between marbofloxacin and gentamicin was found in 33 isolates. The mean FIC index is 0.546, which represents a partial synergistic/additive effect close to the full synergy threshold. In vitro results indicate that marbofloxacin and gentamicin as partially synergistic agents may prove clinically useful in combination therapy against P. aeruginosa infections. Although marbofloxacin is not used in the human practice, the interactions between fluoroquinolones and aminoglycosides may have importance outside the veterinary field

Beyond the Libet clock: modality variants for agency measurements

The Sense of Agency (SoA) refers to our capability to control our own actions and influence the world around us. Recent research in HCI has been exploring SoA to provide users an instinctive sense of “I did that” as opposed to “the system did that”. However, current agency measurements are limited. The Intentional Binding (IB) paradigm provides an implicit measure of the SoA. However, it is constrained by requiring high visual attention to a “Libet clock” onscreen. In this paper, we extend the timing stimulus through auditory and tactile cues. Our results demonstrate that audio timing through voice commands and haptic timing through tactile cues on the hand are alternative techniques to measure the SoA using the IB paradigm. They both address limitations of the traditional method (e.g., lack of engagement and visual demand). We discuss how our results can be applied to measure SoA in tasks involving different interactive scenarios common in HCI

On the overgeneralization of the intransitive/transitive alternation in children's speech: a cross-linguistic account with new evidence from French

This study investigates the cross-linguistic patterns of the overgeneralization of the Intransitive/ Transitive alternations found in children's speech and provides new evidence from findings based on the acquisition of French. The morphosyntactic characterization of such phenomenon in English and Hebrew child language is followed by a description of the morphosyntactic characterization of such alternation in adult French which relies on an account of SE-affixation proposed by Werhli (1986). On the basis of this account, predictions are made with respect to the overgeneralization of the Intransitive/Transitive alternation displayed by French children's speech which is borne out by the data drawn from several corpora. In addition, this account is shown to explain the results of a comprehension task carried out by AnnibaldiVion(1980) which were previously unexplained

Argument structure alternation in French children's speech

Book synopsis: This book is the proceedings of the Child Language Seminar, held 4-6 September 1998, in Sheffield, UK. The book aims to provide an up-to-date overview of current research into child language development and disorders. Its 26 chapters, written by leading authorities around the world, address many of the key issues which are currently exercising the minds of child language researchers, and which are likely to motivate research for some time to come. A key theme of the book is the nature of language acquisition in children whose learning capacity is in some way impaired, and what this can tell us about language development more generally. The main topics covered are: cross-linguistic perspectives on language acquisition; the relationship between innate linguistic capacity and the specific properties of the language being acquired; syntax; argument structure; verbs and verb morphology; phonology; pragmatics and discourse; and literacy

La cliticisation en SE dans le langage de l’enfant: surgénéralisation des affixations et des omissions

Book synopsis (In French): Dans cet ouvrage, on trouvera une somme de recherches sur ce qu'on appelle les "clitiques" dans la linguistique contemporaine: il s'agit de cette catégorie bizarre de mots - s'agit-il d'ailleurs encore de mots? - qui, pris dans des processus de grammaticalisation, évoluent entre les mots pleins, autonomes, et les affixes de toute espèce. Ils ont des propriétés intermédiaires, plus autonomes que des affixes, jamais utilisables isolément, la plupart du temps attachés à un "hôte" mais parfois assignés à une "position" - la fameuse "seconde position" des termes atones, reconnue comme telle par le linguiste allemand Wackernagel il y a plus d'un siècle. En vérité, leur étude remonte à l'aube de la recherche sur la grammaire, puisque le premier à s'y intéresser - d u moins le premier dont il nous reste des écrits - est le grammairien alexandrin Apollonios Dyscole. C'est d'ailleurs par une étude qui lui est consacrée, que commence cet itinéraire sur les clitiques et la cliticisation, qui parcourt le temps (études surle latin ou le gotique) et l'espace (cliticisation dans les langues austronésiennes, dans les langues africaines, en passant par le français et les langues romanes). Ce livre, fruit d'un colloque international tenu à Bordeaux, est destiné à tous ceux que l'évolution des langues et la réflexion linguistique intéressent. Il touche par son sujet à tous les domaines de la linguistique: phonétique, phonologie et prosodie, syntaxe, évolution des langues, et sémantique