Spontaneous rotating vortex rings in a parametrically driven polariton fluid

We present the theoretical prediction of spontaneous rotating vortex rings in a parametrically driven quantum fluid of polaritons -- coherent superpositions of coupled quantum well excitons and microcavity photons. These rings arise not only in the absence of any rotating drive, but also in the absence of a trapping potential, in a model known to map quantitatively to experiments. We begin by proposing a novel parametric pumping scheme for polaritons, with circular symmetry and radial currents, and characterize the resulting nonequilibrium condensate. We show that the system is unstable to spontaneous breaking of circular symmetry via a modulational instability, following which a vortex ring with large net angular momentum emerges, rotating in one of two topologically distinct states. Such rings are robust and carry distinctive experimental signatures, and so they could find applications in the new generation of polaritonic devices.Comment: 6 pages, 4 figure

Cooling of Quark Stars in the Color Superconductive Phase: Effect of Photons from Glueball decay

The cooling history of a quark star in the color superconductive phase is investigated. Here we specifically focus on the 2-flavour color (2SC) phase where novel process of photon generation via glueball (GLB) decay have been already investigated (Ouyed & Sannino 2001). The picture we present here can in principle be generalized to quark stars entering a superconductive phase where similar photon generation mechanisms are at play. As much as 10^{45}-10^{47} erg of energy is provided by the GLB decay in the 2SC phase. The generated photons slowly diffuse out of the quark star keeping it hot and radiating as a black-body (with possibly a Wien spectrum in gamma-rays) for millions of years. We discuss hot radio-quiet isolated neutron stars in our picture (such as RX J185635-3754 and RX J0720.4-3125) and argue that their nearly blackbody spectra (with a few broad features) and their remarkably tiny hydrogen atmosphere are indications that these might be quark stars in the color superconductive phase where some sort of photon generation mechanism (reminiscent of the GLB decay) has taken place. Fits to observed data of cooling compact stars favor models with superconductive gaps of Delta_2SC = 15-35 MeV and densities rho_2SC=(2.5-3.0)rho_N (rho_N being the nuclear matter saturation density) for quark matter in the 2SC phase. If correct, our model combined with more observations of isolated compact stars could provide vital information to studies of quark matter and its exotic phases.Comment: 7 journal pages, 4 figures, accepted for publication in MNRAS (more discussions on photon cooling versus neutrino cooling before and after pairing of quarks

ADHD and brain anatomy:What do academic textbooks used in the Netherlands tell students?

Studies of brain size of children classified with ADHD appear to reveal smaller brains when compared to ‘normal’ children. Yet, what does this mean? Even with the use of rigorously screened case and control groups, these studies show only small, average group differences between children with and without an ADHD classification. However, academic textbooks used in the Netherlands often portray individual children with an ADHD classification as having a different, malfunctioning brain that necessitates medical intervention. This conceptualisation of ADHD might serve professional interests, but not necessarily the interests of children

Evolutionary Relationships of Wild Hominids Recapitulated by Gut Microbial Communities

Although bacteria are continually acquired over the lifetime of an individual, the phylogenetic relationships of great ape species is mirrored in the compositions of their gut microbial communities

jMOTU and Taxonerator: Turning DNA Barcode Sequences into Annotated Operational Taxonomic Units

BACKGROUND: DNA barcoding and other DNA sequence-based techniques for investigating and estimating biodiversity require explicit methods for associating individual sequences with taxa, as it is at the taxon level that biodiversity is assessed. For many projects, the bioinformatic analyses required pose problems for laboratories whose prime expertise is not in bioinformatics. User-friendly tools are required for both clustering sequences into molecular operational taxonomic units (MOTU) and for associating these MOTU with known organismal taxonomies. RESULTS: Here we present jMOTU, a Java program for the analysis of DNA barcode datasets that uses an explicit, determinate algorithm to define MOTU. We demonstrate its usefulness for both individual specimen-based Sanger sequencing surveys and bulk-environment metagenetic surveys using long-read next-generation sequencing data. jMOTU is driven through a graphical user interface, and can analyse tens of thousands of sequences in a short time on a desktop computer. A companion program, Taxonerator, that adds traditional taxonomic annotation to MOTU, is also presented. Clustering and taxonomic annotation data are stored in a relational database, and are thus amenable to subsequent data mining and web presentation. CONCLUSIONS: jMOTU efficiently and robustly identifies the molecular taxa present in survey datasets, and Taxonerator decorates the MOTU with putative identifications. jMOTU and Taxonerator are freely available from http://www.nematodes.org/

Linguistica \ue8 storia. Sprachwissenschaft ist Geschichte. Scritti in onore di Carlo De Simone. Festschrift fuer Carlo De Simone.

Gli interventi raccolti in questo omaggio a Carlo De Simone appartengono a colleghi linguisti, ar-cheologi e storici, di varia formazione e prove-nienza, che intendono cos\uec testimoniare l\u2019importanza del contributo offerto dallo studioso in ambito linguisti-co, epigrafico ed onomastico, so-prattutto per quanto riguarda il mondo messapico e quello etrusco. Il titolo del volume \ue8 spia indicati-va per descrivere l\u2019atteggiamento ermeneutico proprio di De Simone e di chi si dedichi allo studio delle lingue antiche, soprattutto di quel-le \uabrelitto\ubb: una fortunata con-giunzione di metodi (strutturali-smo, funzionalismo, sociolingui-stica) inquadrata in uno storici-smo ed in una attenzione al dato archeologico concreto influenzati anche dalla scuola di Massimo Pallottino ed aggiornati dalle pi\uf9 recenti tendenze della linguistica moderna. A questa impostazione, che ha fatto scuola, si devono i meriti di Carlo De Simone e le fortunate proposte d\u2019interpretazione testuale che caratterizzano tutta la sua produzione scientifica

Mitigating the Effect of Language in the Assessment of Science:A study of English-language learners in primary classrooms in the United Kingdom

Children coming from homes where English is not the primary language constitute a significant and increasing proportion of classrooms worldwide. Providing these English language learners (ELLs) with equitable assessment opportunities is a challenge. We analyse the performance of 485 students, both English native speakers and ELLs, across 5 schools within the UK in the 7-11 year age group on standardized Science assessment tasks. Logistic regression with random effects assesses the impact of English language proficiency, and its interactions with question traits, on performance. Traits investigated were: question focus; need for active language production; presence/absence of visuals; and question difficulty. Results demonstrated that, while ELLs persistently performed more poorly, the gap to their native speaking peers depended significantly upon assessment traits. ELLs were particularly disadvantaged when responses required active language production and/or when assessed on specific scientific vocabulary. Visual prompts did not help ELL performance. There was no evidence of an interaction between topic difficulty and language ability suggesting lower ELL performance is not related to capacity to understand advanced topics. We propose assessment should permit flexibility in language choice for ELLs with low English language proficiency; while simultaneously recommend subject-specific teaching of scientific language begins at lower stages of schooling

Experimental Animal Models in Periodontology: A Review

In periodontal research, animal studies are complementary to in vitro experiments prior to testing new treatments. Animal models should make possible the validation of hypotheses and prove the safety and efficacy of new regenerating approaches using biomaterials, growth factors or stem cells. A review of the literature was carried out by using electronic databases (PubMed, ISI Web of Science). Numerous animal models in different species such as rats, hamsters, rabbits, ferrets, canines and primates have been used for modeling human periodontal diseases and treatments. However, both the anatomy and physiopathology of animals are different from those of humans, making difficult the evaluation of new therapies. Experimental models have been developed in order to reproduce major periodontal diseases (gingivitis, periodontitis), their pathogenesis and to investigate new surgical techniques. The aim of this review is to define the most pertinent animal models for periodontal research depending on the hypothesis and expected results