Geometric Analysis of Bifurcation and Symmetry Breaking in a Gross-Pitaevskii equation

Gross-Pitaevskii and nonlinear Hartree equations are equations of nonlinear Schroedinger type, which play an important role in the theory of Bose-Einstein condensation. Recent results of Aschenbacher et. al. [AFGST] demonstrate, for a class of 3- dimensional models, that for large boson number (squared L^2 norm), N, the ground state does not have the symmetry properties as the ground state at small N. We present a detailed global study of the symmetry breaking bifurcation for a 1-dimensional model Gross-Pitaevskii equation, in which the external potential (boson trap) is an attractive double-well, consisting of two attractive Dirac delta functions concentrated at distinct points. Using dynamical systems methods, we present a geometric analysis of the symmetry breaking bifurcation of an asymmetric ground state and the exchange of dynamical stability from the symmetric branch to the asymmetric branch at the bifurcation point.Comment: 22 pages, 7 figure

Law, Language and Legal Determinacy

Book review of Law, Language and Legal Determinacy by Brian Bix and published by Clarendon Press (Oxford), 1993. (221 pp.

Harsh Parenting as a Predictor of Physical, Verbal, and Relational Aggression in Children

Harsh parenting is positively correlated with aggression in children (e.g., Aucoin, Frick, & Bodin, 2006; Chang et al, 2003). However, little attention has been given to the potential relationship between harsh parenting and other types of child aggression. Harsh parenting is positively correlated with child aggression (e.g., Aucoin, Frick, & Bodin, 2006; Chang et al, 2003). However, little is known about harsh parenting’s relationship with other types of aggression. The current study ran a model of abusive parenting as a predictor of physical, verbal, and relational child aggression. Age, sex, and parental income were controlled. Results showed that harsh parenting was most strongly related to physical aggression (β = 0.24, p \u3c 0.01), weakly, yet significantly, related to verbal aggression (β = 0.14, p \u3c 0.05), and not related to relational aggression (β = 0.09, p \u3e 0.05). Further analyses concluded that each relationship significantly differed from one another, indicating that harsh parenting better predicts child physical aggression than verbal or relational aggression, and does not significantly predict relational aggression. Social Learning Theory accounts for these findings. Presented with physically harsh parenting, children will act physically aggressive (more so than verbally or relationally). Future research should address potential links between various types of harsh parenting practices (verbal abuse and relational aggression) and their respective types of child aggression. A longitudinal study needs to be conducted to clarify the directionality in the relationship between harsh parenting and child aggression

‘All a matter of scale’? – Shakespearean acting and the cinema’s eyes and ears

The paper discusses the acting of Shakespeare’s plays for the screen, in the light of the conventional wisdom that a film actor should simply “do less.” Starting from V. I. Pudovkin’s influential work on Film Technique and Film Acting, it addresses the question of “incongruity” as a source of a sense of “staginess” in film performances. It is suggested that a degree of “incongruity” is created by the physical as well as vocal demands on the actor of speaking the Shakespearean dialogue, and by the potential unfamiliarity for audiences of dialogue that is more copious than that of most mainstream films and at the same time is in an unfamiliar idiom. Films are cited from the silent era to the present century, and the paper concludes with examples from Kenneth Branagh’s 1996 Hamlet, for which the author was text adviser.L’objet de cet article est d’étudier la manière dont on joue les pièces de Shakespeare à l’écran, à la lumière de l’idée conventionnelle selon laquelle un acteur de cinéma devrait se contenter « d’en faire moins ». À partir du livre de V. I. Pudovkin Film Techniques and Film Acting, qui fait autorité, cet article aborde la question de l’« incongruité » qui fait naître le sentiment que le théâtre au cinéma d’un manque de naturel. On développera l’idée qu’un degré d’« incongruité » est créé par les exigences aussi bien physiques que vocales qui s’imposent aux acteurs qui disent le texte shakespearien, ainsi que par le fait que le public est peut-être moins accoutumé à des dialogues beaucoup plus longs que ceux de la plupart des films grand public, rédigés dans une langue à laquelle il n’est pas habitué. Les films cités vont du cinéma muet au 21e siècle et l’article se termine avec des exemples extraits du Hamlet (1996) de Kenneth Branagh, film pour lequel l’auteur a agi en tant que conseiller dramaturgique

Learning and Exposure Affect Environmental Perception Less than Evolutionary Navigation Costs

Russell E. Jackson is with University of Idaho, Chéla R. Willey is with University of California Los Angeles, Lawrence K. Cormack is with UT Austin.Most behaviors are conditional upon successful navigation of the environment, which depends upon distance perception learned over repeated trials. Unfortunately, we understand little about how learning affects distance perception–especially in the most common human navigational scenario, that of adult navigation in familiar environments. Further, dominant theories predict mutually exclusive effects of learning on distance perception, especially when the risks or costs of navigation differ. We tested these competing predictions in four experiments in which we also presented evolutionarily relevant navigation costs. Methods included within- and between-subjects comparisons and longitudinal designs in laboratory and real-world settings. Data suggested that adult distance estimation rapidly reflects evolutionarily relevant navigation costs and repeated exposure does little to change this. Human distance perception may have evolved to reflect navigation costs quickly and reliably in order to provide a stable signal to other behaviors and with little regard for objective accuracy.Psycholog

The regulation of host translation initiation in plant-pathogen interactions

Pathogens dramatically alter plant mRNA transcript levels by activating and repressing a variety of signaling pathways. However, the effects of plant pathogens on host mRNA translation have not been explored on a genome-wide scale. To assess pathogen-induced changes in host mRNA transcription and translation, we conducted DNA microarray analysis of total and polyribosomal RNA fractions in the Arabidopsis thaliana–Turnip mosaic virus (TuMV) and barley-powdery mildew (Hordeum vulgare–Blumeria graminis f.sp. hordei (Bgh)) interactions. The ratios of mRNA transcript abundance in total versus polyribosomal RNA fractions were compared between inoculated and non-inoculated sample types to identify mRNAs that were differentially regulated at the level of translation. The majority of mRNA transcripts had ratios that were consistent for the non-inoculated and inoculated treatments indicating that they were not differentially translated. However, infection did alter the mRNA transcript abundance of a subset of genes in polyribosomal RNA independent of the abundance of these transcripts in total RNA in both Arabidopsis and barley. In both hosts, approximately one-half of these mRNAs had enhanced association with polyribosomal RNA in response to inoculation while the other half had reduced association with polyribosomal RNA. These results suggest that pathogen infection can cause either enhanced or reduced translation of select sets of plant mRNAs. Analysis of the sequence features of mRNAs that were differentially associated with polyribosomal RNA suggest that TuMV infection leads to a decreased ability to translate mRNAs containing upstream AUG sequences and an increased ability to translate mRNAs with short 5\u27 and 3\u27 UTRs. Sequence analyses of the selectively translated mRNAs identified in barley (using rice orthologs as a surrogate) showed that the compatible interaction was strongly correlated with decreased length and significant mono– and di–nucleotide frequencies. Analysis of overrepresented gene function categories among selectively translated mRNAs identified related sets of genes that were unique to each interaction as well as gene sets that were identified in common to the interactions. In both host-pathogen interactions, a comparison of induced and repressed transcripts of the total and polyribosomal RNA fractions indicated that approximately 10% of interesting mRNA transcripts would be misidentified or not identified if expression profiling was only performed on the total RNA fraction. This work establishes that many host mRNAs are selectively translated in response to pathogen inoculation. Furthermore, many of these mRNAs are overrepresented among groups of genes with specific biological functions, and mRNA sequence features are strongly correlated with particular patterns of selective translation

Trouble at work: A model testing relationships among job strain, social support, cooperativeness, and well-being

The purpose of this study is to test a model proposing that levels of cooperativeness at work affect job strain, as mediated by perceived social support, thereby affecting overall mental well-being

Bridging the synaptic gap: neuroligins and neurexin I in Apis mellifera

Vertebrate studies show neuroligins and neurexins are binding partners in a trans-synaptic cell adhesion complex, implicated in human autism and mental retardation disorders. Here we report a genetic analysis of homologous proteins in the honey bee. As in humans, the honeybee has five large (31-246 kb, up to 12 exons each) neuroligin genes, three of which are tightly clustered. RNA analysis of the neuroligin-3 gene reveals five alternatively spliced transcripts, generated through alternative use of exons encoding the cholinesterase-like domain. Whereas vertebrates have three neurexins the bee has just one gene named neurexin I (400 kb, 28 exons). However alternative isoforms of bee neurexin I are generated by differential use of 12 splice sites, mostly located in regions encoding LNS subdomains. Some of the splice variants of bee neurexin I resemble the vertebrate alpha- and beta-neurexins, albeit in vertebrates these forms are generated by alternative promoters. Novel splicing variations in the 3' region generate transcripts encoding alternative trans-membrane and PDZ domains. Another 3' splicing variation predicts soluble neurexin I isoforms. Neurexin I and neuroligin expression was found in brain tissue, with expression present throughout development, and in most cases significantly up-regulated in adults. Transcripts of neurexin I and one neuroligin tested were abundant in mushroom bodies, a higher order processing centre in the bee brain. We show neuroligins and neurexins comprise a highly conserved molecular system with likely similar functional roles in insects as vertebrates, and with scope in the honeybee to generate substantial functional diversity through alternative splicing. Our study provides important prerequisite data for using the bee as a model for vertebrate synaptic development.Australian National University PhD Scholarship Award to Sunita Biswas