Propagation of ultra-high energy protons in regular extragalactic magnetic fields

We study the proton flux expected from sources of ultra high energy cosmic rays (UHECR) in the presence of regular extragalactic magnetic fields. It is assumed that a local source of ultra-high energy protons and the magnetic field are all in a wall of matter concentration with dimensions characteristic of the supergalactic plane. For a single source, the observed proton flux and the local cosmic ray energy spectrum depend strongly on the strength of the field, the position of the observer, and the orientation of the field relative to the observer's line of sight. Regular fields also affect protons emitted by sources outside the local magnetic fields structure. We discuss the possibility that such effects could contribute to an explanation of the excess of UHECR above $5.10^{19}$ eV, and the possibility that sources of such particles may be missed if such magnetic fields are not taken into account.Comment: 6 pages, 4 figures Comments for revised version: 12 pages, 12 figures. Enlarged discussion of effects on cosmic ray spectrum. Additional discussion focussing on spatial and temporal boundary condition

Fitting the integrated Spectral Energy Distributions of Galaxies

Fitting the spectral energy distributions (SEDs) of galaxies is an almost universally used technique that has matured significantly in the last decade. Model predictions and fitting procedures have improved significantly over this time, attempting to keep up with the vastly increased volume and quality of available data. We review here the field of SED fitting, describing the modelling of ultraviolet to infrared galaxy SEDs, the creation of multiwavelength data sets, and the methods used to fit model SEDs to observed galaxy data sets. We touch upon the achievements and challenges in the major ingredients of SED fitting, with a special emphasis on describing the interplay between the quality of the available data, the quality of the available models, and the best fitting technique to use in order to obtain a realistic measurement as well as realistic uncertainties. We conclude that SED fitting can be used effectively to derive a range of physical properties of galaxies, such as redshift, stellar masses, star formation rates, dust masses, and metallicities, with care taken not to over-interpret the available data. Yet there still exist many issues such as estimating the age of the oldest stars in a galaxy, finer details ofdust properties and dust-star geometry, and the influences of poorly understood, luminous stellar types and phases. The challenge for the coming years will be to improve both the models and the observational data sets to resolve these uncertainties. The present review will be made available on an interactive, moderated web page (sedfitting.org), where the community can access and change the text. The intention is to expand the text and keep it up to date over the coming years.Comment: 54 pages, 26 figures, Accepted for publication in Astrophysics & Space Scienc

Novel genetic loci associated with hippocampal volume

The hippocampal formation is a brain structure integrally involved in episodic memory, spatial navigation, cognition and stress responsiveness. Structural abnormalities in hippocampal volume and shape are found in several common neuropsychiatric disorders. To identify the genetic underpinnings of hippocampal structure here we perform a genome-wide association study (GWAS) of 33,536 individuals and discover six independent loci significantly associated with hippocampal volume, four of them novel. Of the novel loci, three lie within genes (ASTN2, DPP4 and MAST4) and one is found 200 kb upstream of SHH. A hippocampal subfield analysis shows that a locus within the MSRB3 gene shows evidence of a localized effect along the dentate gyrus, subiculum, CA1 and fissure. Further, we show that genetic variants associated with decreased hippocampal volume are also associated with increased risk for Alzheimer's disease (rg =-0.155). Our findings suggest novel biological pathways through which human genetic variation influences hippocampal volume and risk for neuropsychiatric illness

Novel genetic loci associated with hippocampal volume

The hippocampal formation is a brain structure integrally involved in episodic memory, spatial navigation, cognition and stress responsiveness. Structural abnormalities in hippocampal volume and shape are found in several common neuropsychiatric disorders. To identify the genetic underpinnings of hippocampal structure here we perform a genome-wide association study (GWAS) of 33,536 individuals and discover six independent loci significantly associated with hippocampal volume, four of them novel. Of the novel loci, three lie within genes (ASTN2, DPP4 and MAST4) and one is found 200 kb upstream of SHH. A hippocampal subfield analysis shows that a locus within the MSRB3 gene shows evidence of a localized effect along the dentate gyrus, subiculum, CA1 and fissure. Further, we show that genetic variants associated with decreased hippocampal volume are also associated with increased risk for Alzheimer’s disease (rg=−0.155). Our findings suggest novel biological pathways through which human genetic variation influences hippocampal volume and risk for neuropsychiatric illness

The effectiveness of communication groups in day nurseries

This project, run by a speech and language therapist and a clinical psychologist, took place in three inner city day nurseries. A group of children over whose communication there was concern were assessed on both formal (verbal and non‐verbal) and informal (observational) measures. At each nursery these children were divided into two matched groups: intervention and control. The intervention consisted of communication groups run jointly with nursery staff. These small groups focused on promoting communication through play. On reassessment the children attending the communication groups had made significantly more improvement than the controls on both formal and informal measures. In particular, the number and quality of children's interactions, their underlying ability to focus on tasks and their knowledge of basic concepts appeared to benefit from the intervention. The study, therefore, provides strong evidence for the efficacy of such interventions in enhancing communication development in a real‐life setting. Cette étude, effectuée par un orthophoniste et un psychologue clinique, s'est déroulée dans trois crèches de jour urbaines. Un groupe d'enfants, dont la capacité à communiquer causait des inquiétudes, a été évalué a la fois selon des critères formels (verbaux at non verbaux) et informels (fondés sur l'observation). Dans chaque crèche ces enfants ont été divisés en deux groupes semblables: un groupe d'intervention et un de contrǒle. L'intervention consistait en l'établissement de petits groupes de communication gérés en association avec le personnel des crèches. Ces petits groupes avient pour but de promouvoir la communication à travers l'activité ludique. Une évaluation ultérieure a permis de voir des améliorations significativement plus importantes chez les enfants qui avaient pris part aux groupes de communication qu'au sein des groupes de contrǒle, en ce qui concernait tant les critères formels qu'informels. En particulier, le nombre et la qualité des interactions entre enfants, leur capacité intrinsèque de s'appliquer à des tǎches et leurs connaissances de concepts fondamentaux semblent avoir bénéficié de l'intervention. Par conséquent l'étude confirme nettement l'efficacité de ce type d'interventions pour le développement de la communication dans le cadre de la vie réelle. Dieses Projekt wurde von einem Sprachtherapeuten und einem klinischen Psychologen in drei Kindergarten des inneren Stadtbereiches durchgeführt. Eine Gruppe von Kindern, deren Kommunikationsvermögen zur Sorge Anlaß gab, wurde hinsichtlich formaler (verbal und nichtverbal) und informeller Kriterien (Beobachtungen) bewertet. In jeder Tagesstätte wurden die Kinder in gepaarte Gruppen eingeteilt: Kontrollgruppe und Behandlungsgruppe. Die Behandlungfand in Kommunikationsgruppen statt, die wir zusammen mit dem Kindergartenpersonal leiteten. Ziel dieser kleinen Gruppen war die Förderung der Kommunikation beim Spiel. Eine Folgeuntersuchung zeigte eine signifikant stärkere Besserung der Kommunikation hinsichtlich der formalen und der informellen Bewertungsmaße bei den Kindern in den Kommunikationsgruppen. Insbesondere wurden die Anzahl und die Qualität der Interaktionen, die Fähigkeit der Kinder, sich auf Aufgaben zu konzentrieren, und das Verständnis von grundlegenden Begriffen durch die Behandlung positiv beeinflußt. Die Untersuchung bietet daher positive Evidenz für die Wirksamkeit solcher Behandlungsmethoden bei der Förderung der Kommunikationsentwicklung im Alltag. 1993 Royal College of Speech & Language Therapist

Multiethnic Genome-Wide Association Study of Cerebral White Matter Hyperintensities on MRI

Pathophysiology, epidemiology and therapy of agein