Interstellar scintillation as the origin of rapid radio variability in the quasar J1819+3845

Quasars shine brightly due to the liberation of gravitational energy as matter falls onto a supermassive black hole in the centre of a galaxy. Variations in the radiation received from active galactic nuclei (AGN) are studied at all wavelengths, revealing the tiny dimensions of the region and the processes of fuelling the black hole. Some AGN are variable at optical and shorter wavelengths, and display radio outbursts over years and decades. These AGN often also show faster variations at radio wavelengths (intraday variability, IDV) which have been the subject of much debate. The simplest explanation, supported by a correlation in some sources between the optical (intrinsic) and faster radio variations, is that the rapid radio variations are intrinsic. However, this explanation implies physically difficult brightness temperatures, suggesting that the variations may be due to scattering of the incident radiation in the interstellar medium of our Galaxy. Here we present results which show unambiguously that the variations in one extreme case are due to interstellar scintillation. We also measure the transverse velocity of the scattering material, revealing a surprising high velocity plasma close to the Solar System

The contribution of diet and genotype to iron status in women:a classical twin study

This is the first published report examining the combined effect of diet and genotype on body iron content using a classical twin study design. The aim of this study was to determine the relative contribution of genetic and environmental factors in determining iron status. The population was comprised of 200 BMI- and age-matched pairs of MZ and DZ healthy twins, characterised for habitual diet and 15 iron-related candidate genetic markers. Variance components analysis demonstrated that the heritability of serum ferritin (SF) and soluble transferrin receptor was 44% and 54% respectively. Measured single nucleotide polymorphisms explained 5% and selected dietary factors 6% of the variance in iron status; there was a negative association between calcium intake and body iron (p = 0.02) and SF (p = 0.04)

Computational modeling with spiking neural networks

This chapter reviews recent developments in the area of spiking neural networks (SNN) and summarizes the main contributions to this research field. We give background information about the functioning of biological neurons, discuss the most important mathematical neural models along with neural encoding techniques, learning algorithms, and applications of spiking neurons. As a specific application, the functioning of the evolving spiking neural network (eSNN) classification method is presented in detail and the principles of numerous eSNN based applications are highlighted and discussed

The bashful and the boastful : prestigious leaders and social change in Mesolithic Societies

The creation and maintenance of influential leaders and authorities is one of the key themes of archaeological and historical enquiry. However the social dynamics of authorities and leaders in the Mesolithic remains a largely unexplored area of study. The role and influence of authorities can be remarkably different in different situations yet they exist in all societies and in almost all social contexts from playgrounds to parliaments. Here we explore the literature on the dynamics of authority creation, maintenance and contestation in egalitarian societies, and discuss the implications for our interpretation and understanding of the formation of authorities and leaders and changing social relationships within the Mesolithic

Evolutionary trade-offs underlie the multi-faceted virulence of Staphylococcus aureus

Published onlineJournal ArticleResearch Support, Non-U.S. Gov'tBacterial virulence is a multifaceted trait where the interactions between pathogen and host factors affect the severity and outcome of the infection. Toxin secretion is central to the biology of many bacterial pathogens and is widely accepted as playing a crucial role in disease pathology. To understand the relationship between toxicity and bacterial virulence in greater depth, we studied two sequenced collections of the major human pathogen Staphylococcus aureus and found an unexpected inverse correlation between bacterial toxicity and disease severity. By applying a functional genomics approach, we identified several novel toxicity-affecting loci responsible for the wide range in toxic phenotypes observed within these collections. To understand the apparent higher propensity of low toxicity isolates to cause bacteraemia, we performed several functional assays, and our findings suggest that within-host fitness differences between high- and low-toxicity isolates in human serum is a contributing factor. As invasive infections, such as bacteraemia, limit the opportunities for onward transmission, highly toxic strains could gain an additional between-host fitness advantage, potentially contributing to the maintenance of toxicity at the population level. Our results clearly demonstrate how evolutionary trade-offs between toxicity, relative fitness, and transmissibility are critical for understanding the multifaceted nature of bacterial virulence

The SINS trial: A randomised controlled trial of excisional surgery versus imiquimod 5% cream for nodular and superficial basal cell carcinoma

<p>Abstract</p> <p>Background</p> <p>Basal cell carcinoma is the commonest human cancer. Despite increasing incidence it remains poorly researched. While not life threatening it can cause significant cosmetic disfigurement. Imiquimod, a cream which enhances the body's immune response, may help deal with the number of cases that occur in low-risk sites, especially when good cosmetic results and home use without surgery are needed.</p> <p>This study aims 1. To compare excisional surgery with imiquimod cream for nodular or superficial basal cell carcinoma in low risk sites, with respect to 3 year clinical clearance, cost-effectiveness and cosmetic results. 2. To ascertain if certain phenotypic features and gene polymorphisms predict tumour responsiveness to treatment.</p> <p>Methods/Design</p> <p>Five hundred participants with low risk nodular or superficial basal cell carcinoma will be recruited from hospitals to this multi-centre, randomised, parallel group, controlled phase III trial. Treatment in the imiquimod group is for 6 weeks for superficial basal cell carcinoma and 12 weeks for nodular basal cell carcinoma. Both treatment groups are followed up in clinic for 3 years. Primary outcome variable: the proportion of participants with clinical evidence of success (no recurrence) at 3 years. The primary outcome will be compared between the two treatment groups. Secondary outcomes include: i) clinical success at 1, 2 and 5 years, ii) time to first recurrence, iii) cosmetic appearance of lesion site after treatment, iv) level of pain, and v) cost-effectiveness. Safety and tolerability data will also be reported.</p> <p>Discussion</p> <p>This study protocol describes a pragmatic randomised controlled trial which it is hoped will address the above uncertainties. Three-year results will be available towards the end of 2010.</p> <p>Trial registration</p> <p>Meta-register: NCT00066872, Eudract No. 2004-004506-24, ISRCTN48755084.</p

Ultra-Rapid Categorization of Fourier-Spectrum Equalized Natural Images: Macaques and Humans Perform Similarly

BACKGROUND: Comparative studies of cognitive processes find similarities between humans and apes but also monkeys. Even high-level processes, like the ability to categorize classes of object from any natural scene under ultra-rapid time constraints, seem to be present in rhesus macaque monkeys (despite a smaller brain and the lack of language and a cultural background). An interesting and still open question concerns the degree to which the same images are treated with the same efficacy by humans and monkeys when a low level cue, the spatial frequency content, is controlled. METHODOLOGY/PRINCIPAL FINDINGS: We used a set of natural images equalized in Fourier spectrum and asked whether it is still possible to categorize them as containing an animal and at what speed. One rhesus macaque monkey performed a forced-choice saccadic task with a good accuracy (67.5% and 76% for new and familiar images respectively) although performance was lower than with non-equalized images. Importantly, the minimum reaction time was still very fast (100 ms). We compared the performances of human subjects with the same setup and the same set of (new) images. Overall mean performance of humans was also lower than with original images (64% correct) but the minimum reaction time was still short (140 ms). CONCLUSION: Performances on individual images (% correct but not reaction times) for both humans and the monkey were significantly correlated suggesting that both species use similar features to perform the task. A similar advantage for full-face images was seen for both species. The results also suggest that local low spatial frequency information could be important, a finding that fits the theory that fast categorization relies on a rapid feedforward magnocellular signal

Parametric study of EEG sensitivity to phase noise during face processing

&lt;b&gt;Background: &lt;/b&gt; The present paper examines the visual processing speed of complex objects, here faces, by mapping the relationship between object physical properties and single-trial brain responses. Measuring visual processing speed is challenging because uncontrolled physical differences that co-vary with object categories might affect brain measurements, thus biasing our speed estimates. Recently, we demonstrated that early event-related potential (ERP) differences between faces and objects are preserved even when images differ only in phase information, and amplitude spectra are equated across image categories. Here, we use a parametric design to study how early ERP to faces are shaped by phase information. Subjects performed a two-alternative force choice discrimination between two faces (Experiment 1) or textures (two control experiments). All stimuli had the same amplitude spectrum and were presented at 11 phase noise levels, varying from 0% to 100% in 10% increments, using a linear phase interpolation technique. Single-trial ERP data from each subject were analysed using a multiple linear regression model. &lt;b&gt;Results: &lt;/b&gt; Our results show that sensitivity to phase noise in faces emerges progressively in a short time window between the P1 and the N170 ERP visual components. The sensitivity to phase noise starts at about 120–130 ms after stimulus onset and continues for another 25–40 ms. This result was robust both within and across subjects. A control experiment using pink noise textures, which had the same second-order statistics as the faces used in Experiment 1, demonstrated that the sensitivity to phase noise observed for faces cannot be explained by the presence of global image structure alone. A second control experiment used wavelet textures that were matched to the face stimuli in terms of second- and higher-order image statistics. Results from this experiment suggest that higher-order statistics of faces are necessary but not sufficient to obtain the sensitivity to phase noise function observed in response to faces. &lt;b&gt;Conclusion: &lt;/b&gt; Our results constitute the first quantitative assessment of the time course of phase information processing by the human visual brain. We interpret our results in a framework that focuses on image statistics and single-trial analyses

Prediction of 7-year psychopathology from mother-infant joint attention behaviours: a nested case–control study

&lt;br&gt;Background: To investigate whether later diagnosis of psychiatric disorder can be predicted from analysis of mother-infant joint attention (JA) behaviours in social-communicative interaction at 12 months.&lt;/br&gt; &lt;br&gt;Method: Using data from a large contemporary birth cohort, we examined 159 videos of a mother-infant interaction for joint attention behaviour when children were aged one year, sampled from within the Avon Longitudinal Study of Parents and Children (ALSPAC) cohort. Fifty-three of the videos involved infants who were later considered to have a psychiatric disorder at seven years and 106 were same aged controls. Psychopathologies included in the case group were disruptive behaviour disorders, oppositional-conduct disorder, attention-deficit/hyperactivity disorder, pervasive development disorder, anxiety and depressive disorders. Psychiatric diagnoses were obtained using the Development and Wellbeing Assessment when the children were seven years old.&lt;/br&gt; &lt;br&gt;Results: None of the three JA behaviours (shared look rate, shared attention rate and shared attention intensity) showed a significant association with the primary outcome of case–control status. Only shared look rate predicted any of the exploratory sub-diagnosis outcomes and was found to be positively associated with later oppositional-conduct disorders (OR [95% CI]: 1.5 [1.0, 2.3]; p = 0.041).&lt;/br&gt;&lt;br&gt;Conclusions: JA behaviours did not, in general, predict later psychopathology. However, shared look was positively associated with later oppositional-conduct disorders. This suggests that some features of JA may be early markers of later psychopathology. Further investigation will be required to determine whether any JA behaviours can be used to screen for families in need of intervention.&lt;/br&gt

An inter-laboratory comparison of urinary 3-hydroxypropylmercapturic acid measurement demonstrates good reproducibility between laboratories

<p>Abstract</p> <p>Background</p> <p>Biomarkers have been used extensively in clinical studies to assess toxicant exposure in smokers and non-smokers and have recently been used in the evaluation of novel tobacco products. The urinary metabolite 3-HPMA, a metabolite of the major tobacco smoke toxicity contributor acrolein, is one example of a biomarker used to measure exposure to tobacco smoke. A number of laboratories have developed liquid chromatography with tandem mass spectrometry (LC-MS/MS) based methods to measure urinary 3-HPMA; however, it is unclear to what extent the data obtained by these different laboratories are comparable.</p> <p>Findings</p> <p>This report describes an inter-laboratory comparison carried out to evaluate the comparability of 3-HPMA measurement between four laboratories. A common set of spiked and authentic smoker and non-smoker urine samples were used. Each laboratory used their in-house LC-MS/MS method and a common internal standard. A comparison of the repeatability ('r'), reproducibility ('R'), and coefficient of variation for 3-HPMA demonstrated that within-laboratory variation was consistently lower than between-laboratory variation. The average inter-laboratory coefficient of variation was 7% for fortified urine samples and 16.2% for authentic urine samples. Together, this represents an inter-laboratory variation of 12.2%.</p> <p>Conclusion</p> <p>The results from this first inter-laboratory comparison for the measurement of 3-HPMA in urine demonstrate a reasonably good consensus between laboratories. However, some consistent measurement biases were still observed between laboratories, suggesting that additional work may be required to further reduce the inter-laboratory coefficient of variation.</p