A Model of Void Formation

We introduce a simple model for the formation of voids. In this model the underdensity of galaxies in voids is the product of two factors. The first arises from a gravitational expansion of the negative density perturbation. The second is due to biasing: galaxies are less likely to form in an underdense region. One feature of the model is an upper cutoff in void sizes. We calculate the volume filling factor of characteristic voids for different CDM models and find that our formation model points to $\Lambda$CDM models as preferred models of the power spectrum. A natural consequence of our model is that the underdensity of the dark matter inside voids is smaller than the galaxy underdensity.Comment: 15 pages, Latex, 5 figures. Accepted for publication in AP

Fluctuation analysis of the far-infrared background — information from the confusion

We investigate the extent to which one can use a P(D) analysis to extract number counts of unclustered sources from maps of the far-infrared background. Such maps currently available, and those expected to emerge in the near future, are dominated by confusion noise resulting from poor resolution. We simulate background maps with an underlying two-slope model for N(S), and we find that, in an experiment of FIRBACK type, we can extract the high-flux slope with an error of a few per cent, whereas other parameters are not so well constrained. However, we find that, in a SIRTF-type experiment, all parameters of this N(S) model can be extracted with errors of only few per cen

Association of school absence and exclusion with recorded neurodevelopmental disorders, mental disorders, or self-harm: a nationwide, retrospective, electronic cohort study of children and young people in Wales, UK

BackgroundPoor attendance at school, whether due to absenteeism or exclusion, leads to multiple social, educational, and lifelong socioeconomic disadvantages. We aimed to measure the association between a broad range of diagnosed neurodevelopmental and mental disorders and recorded self-harm by the age of 24 years and school attendance and exclusion.MethodsIn this nationwide, retrospective, electronic cohort study, we drew a cohort from the Welsh Demographic Service Dataset, which included individuals aged 7–16 years (16 years being the school leaving age in the UK) enrolled in state-funded schools in Wales in the academic years 2012/13–2015/16 (between Sept 1, 2012, and Aug 31, 2016). Using the Adolescent Mental Health Data Platform, we linked attendance and exclusion data to national demographic and primary and secondary health-care datasets. We identified all pupils with a recorded diagnosis of neurodevelopmental disorders (ADHD and autism spectrum disorder [ASD]), learning difficulties, conduct disorder, depression, anxiety, eating disorders, alcohol or drugs misuse, bipolar disorder, schizophrenia, other psychotic disorders, or recorded self-harm (our explanatory variables) before the age of 24 years. Outcomes were school absence and exclusion. Generalised estimating equations with exchangeable correlation structures using binomial distribution with the logit link function were used to calculate odds ratios (OR) for absenteeism and exclusion, adjusting for sex, age, and deprivation.FindingsSchool attendance, school exclusion, and health-care data were available for 414 637 pupils (201 789 [48·7%] girls and 212 848 [51·3%] boys; mean age 10·5 years [SD 3·8] on Sept 1, 2012; ethnicity data were not available). Individuals with a record of a neurodevelopmental disorder, mental disorder, or self-harm were more likely to be absent or excluded in any school year than were those without a record. Unadjusted ORs for absences ranged from 2·1 (95% CI 2·0–2·2) for those with neurodevelopmental disorders to 6·6 (4·9–8·3) for those with bipolar disorder. Adjusted ORs (aORs) for absences ranged from 2·0 (1·9–2·1) for those with neurodevelopmental disorders to 5·5 (4·2–7·2) for those with bipolar disorder. Unadjusted ORs for exclusion ranged from 1·7 (1·3–2·2) for those with eating disorders to 22·7 (20·8–24·7) for those with a record of drugs misuse. aORs for exclusion ranged from 1·8 (1·5–2·0) for those with learning difficulties to 11·0 (10·0–12·1) for those with a record of drugs misuse.InterpretationChildren and young people up to the age of 24 years with a record of a neurodevelopmental or mental disorder or self-harm before the age of 24 years were more likely to miss school than those without a record. Exclusion or persistent absence are potential indicators of current or future poor mental health that are routinely collected and could be used to target assessment and early intervention. Integrated school-based and health-care strategies to support young peoples' engagement with school life are required.FundingThe Medical Research Council, MQ Mental Health Research, and the Economic and Social Research Council.TranslationFor the Welsh translation of the abstract see Supplementary Materials section

Large Sequence Diversity within the Biosynthesis Locus and Common Biochemical Features of Campylobacter coli Lipooligosaccharides

Despite the importance of lipooligosaccharides (LOS) in the pathogenicity of campylobacteriosis, little is known about the genetic and phenotypic diversity of LOS in C. coli. In this study, we investigated the distribution of LOS locus classes among a large collection of unrelated C. coli isolates sampled from several different host species. Furthermore, we paired C. coli genomic information and LOS chemical composition for the first time to identify mechanisms consistent with the generation of LOS phenotypic heterogeneity. After classifying three new LOS locus classes, only 85% of the 144 isolates tested were assigned to a class, suggesting higher genetic diversity than previously thought. This genetic diversity is at the basis of a completely unexplored LOS structure heterogeneity. Mass spectrometry analysis of the LOS of nine isolates, representing four different LOS classes, identified two features distinguishing C. coli LOS from C. jejuni's. GlcN-GlcN disaccharides were present in the lipid A backbone in contrast to the GlcN3N-GlcN backbone observed in C. jejuni. Moreover, despite that many of the genes putatively involved in Qui3pNAcyl were absence in the genomes of various isolates, this rare sugar was found in the outer core of all C. coli. Therefore, regardless the high genetic diversity of LOS biosynthesis locus in C. coli, we identified species-specific phenotypic features of C. coli LOS which might explain differences between C. jejuni and C. coli in terms of population dynamics and host adaptation

Fluctuation Analysis of the Far-Infrared Background - Information from the Confusion

We are investigating to what extent one can use a P(D) analysis to extract number counts of unclustered sources from maps of the far infrared background. Currently available such maps, and those expected to emerge in near future are dominated by confusion noise due to poor resolution. We simulate background maps with an underlying two slope model for N(S) and we find that in an experiment of FIRBACK type we can extract the high flux slope with an error of few percent while other parameters are not so well constrained. We find, however, that in a SIRTF type experiment all parameters of this N(S) model can be extracted with errors of only few percent.Comment: 21 pages, latex, 6 figures. Accepted for publication, MNRA

The CentriMag Centrifugal Blood Pump as a Benchmark for In Vitro Testing of Hemocompatibility in Implantable Ventricular Assist Devices

Abstract: Implantable ventricular assist devices (VADs) have proven efficient in advanced heart failure patients as a bridge-to-transplant or destination therapy. However, VAD usage often leads to infection, bleeding, and throm-bosis, side effects attributable to the damage to blood cells and plasma proteins. Measuring hemolysis alone does not provide sufficient information to understand total blood damage, and research exploring the impact of cur-rently available pumps on a wider range of blood cell types and plasma proteins such as von Willebrand factor (vWF) is required to further our understanding of safer pump design. The extracorporeal CentriMag (Thoratec Corporation, Pleasanton, CA, USA) has a hemolysis profile within published standards of normalized index of hemolysis levels of less than 0.01 g/100 L at 100 mm Hg bu

Recombination-Mediated Host Adaptation by Avian Staphylococcus aureus

Staphylococcus aureus are globally disseminated among farmed chickens causing skeletal muscle infections, dermatitis, and septicaemia. The emergence of poultry-associated lineages has involved zoonotic transmission from humans to chickens but questions remain about the specific adaptations that promote proliferation of chicken pathogens. We characterized genetic variation in a population of genome-sequenced S. aureus isolates of poultry and humanorigin. Genealogical analysis identified a dominant poultry-associated sequence cluster within the CC5 clonal complex. Poultry and human CC5 isolates were significantly distinct from each other and more recombination events were detected in the poultry isolates. We identified 44 recombination events in 33 genes along the branch extending to the poultry-specific CC5 cluster, and 47 genes were found more often in CC5 poultry isolates compared with those from humans. Many of these gene sequences were common in chicken isolates from other clonal complexes suggesting horizontal gene transfer among poultry associated lineages. Consistent with functional predictions for putative poultry-associated genes, poultry isolates showed enhanced growth at 42 degrees C and greater erythrocyte lysis on chicken blood agar in comparison with human isolates. By combining phenotype information with evolutionary analyses of staphylococcal genomes, we provide evidence of adaptation, following a human-to-poultry host transition. This has important implications for the emergence and dissemination of new pathogenic clones associated with modern agriculture.Peer reviewe