Constraining Torus Models for AGNs Using X-Ray Observations

In Unification Models, Active Galactic Nuclei (AGN) are believed to be surrounded by an axisymmetric structure of dust and gas, which greatly influences their observed properties according to the direction from which they are observed. The main aim of this work is to constrain the properties of this obscuring material using X-Ray observations. The distribution of column densities observed by Chandra in the Chandra Deep Field South is used to determine geometrical constraints for already proposed torus models. It is found that the best torus model is given by a classical `donut shape' with an exponential angular dependency of the density profile. The opening angle is strongly constrained by the observed column densities. Other proposed torus models are clearly rejected by the X-Ray observations.Comment: 10 pages, 4 figures, submitted to A&

Large-Scale Sleep Condition Analysis Using Selfies from Social Media

Sleep condition is closely related to an individual's health. Poor sleep conditions such as sleep disorder and sleep deprivation affect one's daily performance, and may also cause many chronic diseases. Many efforts have been devoted to monitoring people's sleep conditions. However, traditional methodologies require sophisticated equipment and consume a significant amount of time. In this paper, we attempt to develop a novel way to predict individual's sleep condition via scrutinizing facial cues as doctors would. Rather than measuring the sleep condition directly, we measure the sleep-deprived fatigue which indirectly reflects the sleep condition. Our method can predict a sleep-deprived fatigue rate based on a selfie provided by a subject. This rate is used to indicate the sleep condition. To gain deeper insights of human sleep conditions, we collected around 100,000 faces from selfies posted on Twitter and Instagram, and identified their age, gender, and race using automatic algorithms. Next, we investigated the sleep condition distributions with respect to age, gender, and race. Our study suggests among the age groups, fatigue percentage of the 0-20 youth and adolescent group is the highest, implying that poor sleep condition is more prevalent in this age group. For gender, the fatigue percentage of females is higher than that of males, implying that more females are suffering from sleep issues than males. Among ethnic groups, the fatigue percentage in Caucasian is the highest followed by Asian and African American.Comment: 2017 International Conference on Social Computing, Behavioral-Cultural Modeling, & Prediction and Behavior Representation in Modeling and Simulation (SBP-BRiMS'17

Possible thermochemical disequilibrium in the atmosphere of the exoplanet GJ 436b

The nearby extrasolar planet GJ 436b--which has been labelled as a 'hot Neptune'--reveals itself by the dimming of light as it crosses in front of and behind its parent star as seen from Earth. Respectively known as the primary transit and secondary eclipse, the former constrains the planet's radius and mass, and the latter constrains the planet's temperature and, with measurements at multiple wavelengths, its atmospheric composition. Previous work using transmission spectroscopy failed to detect the 1.4-\mu m water vapour band, leaving the planet's atmospheric composition poorly constrained. Here we report the detection of planetary thermal emission from the dayside of GJ 436b at multiple infrared wavelengths during the secondary eclipse. The best-fit compositional models contain a high CO abundance and a substantial methane (CH4) deficiency relative to thermochemical equilibrium models for the predicted hydrogen-dominated atmosphere. Moreover, we report the presence of some H2O and traces of CO2. Because CH4 is expected to be the dominant carbon-bearing species, disequilibrium processes such as vertical mixing and polymerization of methane into substances such as ethylene may be required to explain the hot Neptune's small CH4-to-CO ratio, which is at least 10^5 times smaller than predicted

Considering appropriate replication in the design of animal social network studies

© 2019, The Author(s). Social network analysis has increasingly been considered a useful tool to interpret the complexity of animal social relationships. However, group composition can affect the contact structure of the network resulting in variation between networks. Replication in contact network studies is rarely done but enables determination of possible variation in response across networks. Here we explore the importance of between-group variability in social behaviour and the impact of replication on hypothesis testing. We use an exemplar study of social contact data collected from six replicated networks of cattle before and after the application of a social disturbance treatment. In this replicated study, subtle but consistent changes in animal contact patterns were detected after the application of a social disturbance treatment. We then quantify both within- and between-group variation in this study and explore the importance of varying the number of replicates and the number of individuals within each network, on the precision of the differences in treatment effects for the contact behaviour of the resident cattle. The analysis demonstrates that reducing the number of networks observed in the study would reduce the probability of detecting treatment differences for social behaviours even if the total number of animals was kept the same

The effect of an intervention to improve newly qualified teachers’ interpersonal style, students motivation and psychological need satisfaction in sport-based physical education

Recent developments in self-determination theory research in the educational setting (e.g., Reeve, Deci, & Ryan, 2004), suggest that teachers’ interpersonal style should be considered as consisting of three dimensions: autonomy-support, structure and interpersonal involvement. Based on this theoretical proposition, the purpose of the present study was to test the effects of a training program for three physical education newly qualified teachers on the aforementioned teachers’ overt behaviors and students’ psychological needs satisfaction, self-determined motivation and engagement in sport-based physical education. After a baseline period of four lessons, the teachers attended an informational session on adaptive student motivation and how to support it. The training program also included individualized guidance during the last four lessons of the cycle. Results revealed that from pre- to post-intervention: (1) teachers managed to improve their teaching style in terms of all three dimensions, and (2) students were receptive to these changes, as shown by increases in their reported need satisfaction, self-determined motivation and engagement in the class

Near-Infrared Reverberation by Dusty Clumpy Tori in Active Galactic Nuclei

According to recent models, the accretion disk and black hole in active galactic nuclei are surrounded by a clumpy torus. We investigate the NIR flux variation of the torus in response to a UV flash for various geometries. Anisotropic illumination by the disk and the torus self-occultation contrast our study with earlier works. Both the waning effect of each clump and the torus self-occultation selectively reduce the emission from the region with a short delay. Therefore, the NIR delay depends on the viewing angle (where a more inclined angle leads to a longer delay) and the time response shows an asymmetric profile with a negative skewness, opposing to the results for optically thin tori. The range of the computed delay coincides with the observed one, suggesting that the viewing angle is primarily responsible for the scatter of the observed delay. We also propose that the red NIR-to-optical color of type-1.8/1.9 objects is caused by not only the dust extinction but also the intrinsically red color. Compared with the modest torus thickness, both a thick and a thin tori display the weaker NIR emission. A selection bias is thus expected such that NIR-selected AGNs tend to possess moderately thick tori. A thicker torus shows a narrower and more heavily skewed time profile, while a thin torus produces a rapid response. A super-Eddington accretion rate leads to a much weaker NIR emission due to the disk self-occultation and the disk truncation by the self-gravity. A long delay is expected from an optically thin and/or a largely misaligned torus. A very weak NIR emission, such as in hot-dust-poor active nuclei, can arise from a geometrically thin torus, a super-Eddington accretion rate or a slightly misaligned torus.Comment: 15 pages, 15 figures, Accepted for publication in Ap

Strong negative self regulation of Prokaryotic transcription factors increases the intrinsic noise of protein expression

Background Many prokaryotic transcription factors repress their own transcription. It is often asserted that such regulation enables a cell to homeostatically maintain protein abundance. We explore the role of negative self regulation of transcription in regulating the variability of protein abundance using a variety of stochastic modeling techniques. Results We undertake a novel analysis of a classic model for negative self regulation. We demonstrate that, with standard approximations, protein variance relative to its mean should be independent of repressor strength in a physiological range. Consequently, in that range, the coefficient of variation would increase with repressor strength. However, stochastic computer simulations demonstrate that there is a greater increase in noise associated with strong repressors than predicted by theory. The discrepancies between the mathematical analysis and computer simulations arise because with strong repressors the approximation that leads to Michaelis-Menten-like hyperbolic repression terms ceases to be valid. Because we observe that strong negative feedback increases variability and so is unlikely to be a mechanism for noise control, we suggest instead that negative feedback is evolutionarily favoured because it allows the cell to minimize mRNA usage. To test this, we used in silico evolution to demonstrate that while negative feedback can achieve only a modest improvement in protein noise reduction compared with the unregulated system, it can achieve good improvement in protein response times and very substantial improvement in reducing mRNA levels. Conclusions Strong negative self regulation of transcription may not always be a mechanism for homeostatic control of protein abundance, but instead might be evolutionarily favoured as a mechanism to limit the use of mRNA. The use of hyperbolic terms derived from quasi-steady-state approximation should also be avoided in the analysis of stochastic models with strong repressors

Author Correction: Measuring light scattering and absorption in corals with Inverse Spectroscopic Optical Coherence Tomography (ISOCT): a new tool for non-invasive monitoring.

An amendment to this paper has been published and can be accessed via a link at the top of the paper

Exercise, cognition and Alzheimer’s disease: More is not necessarily better

Regional hypoperfusion, associated with a reduction in cerebral metabolism, is a hallmark of Alzheimer’s disease (AD) and contributes to cognitive decline. Cerebral perfusion and hence cognition can be enhanced by exercise. The present review describes first how the effects of exercise on cerebral perfusion in AD are mediated by nitric oxide (NO) and tissue-type plasminogen activator, the release of which is regulated by NO. A conclusion of clinical relevance is that exercise may not be beneficial for the cognitive functioning of all people with dementia if cardiovascular risk factors are present. The extent to which cardiovascular risk factors play a role in the selection of older people with dementia in clinical studies will be addressed in the second part of the review in which the effects of exercise on cognition are presented. Only eight relevant studies were found in the literature, emphasizing the paucity of studies in this field. Positive effects of exercise on cognition were reported in seven studies, including two that excluded and two that included patients with cardiovascular risk factors. These findings suggest that cardiovascular risk factors do not necessarily undo the beneficial effects of exercise on cognition in cognitively impaired people. Further research is called for, in view of the limitations of the clinical studies reviewed here.