Dust-to-gas ratio resurgence in circumstellar disks due to the formation of giant planets: the case of HD 163296

The amount of dust present in circumstellar disks is expected to steadily decrease with age due to the growth from micron-sized particles to planetesimals and planets. Mature circumstellar disks, however, can be observed to contain significant amounts of dust and possess high dust-to-gas ratios. Using HD 163296 as our case study, we explore how the formation of giant planets in disks can create the conditions for collisionally rejuvenating the dust population, halting or reversing the expected trend. We combine N-body simulations with statistical methods and impact scaling laws to estimate the dynamical and collisional excitation of the planetesimals due to the formation of HD 163296's giant planets. We show that this process creates a violent collisional environment across the disk that can inject collisionally produced second-generation dust into it, significantly contributing to the observed dust-to-gas ratio. The spatial distribution of the dust production can explain the observed local enrichments in HD 163296's inner regions. The results obtained for HD 163296 can be extended to any disk with embedded forming giant planets and may indicate a common evolutionary stage in the life of such circumstellar disks. Furthermore, the dynamical excitation of the planetesimals could result in the release of transient, non-equilibrium gas species like H2O, CO2, NH3 and CO in the disk due to ice sublimation during impacts and, due to the excited planetesimals being supersonic with respect to the gas, could produce bow shocks in the latter that could heat it and cause a broadening of its emission lines.Comment: 18 pages, 9 figures, 2 tables. Accepted for publication on The Astrophysical Journa

The Gas Properties of the W3 GMC: A HARP study

We present 12CO, 13CO and C18O J=3-2 maps of the W3 GMC made at the James Clerk Maxwell Telescope. We combine these observations with Five Colleges Radio Astronomy Observatory CO J=1-0 data to produce the first map of molecular-gas temperatures across a GMC and the most accurate determination of the mass distribution in W3 yet obtained. We measure excitation temperatures in the part of the cloud dominated by triggered star formation (the High Density Layer, HDL) of 15-30 K, while in the rest of the cloud, which is relatively unaffected by triggering (Low Density Layer, LDL), the excitation temperature is generally less than 12 K. We identify a temperature gradient in the HDL which we associate with an age sequence in the embedded massive star-forming regions. We measure the mass of the cloud to be 4.4+/-0.4 x 10^5 solar masses, in agreement with previous estimates. Existing sub-mm continuum data are used to derive the fraction of gas mass in dense clumps as a function of position in the cloud. This fraction, which we interpret as a Clump Formation Efficiency (CFE), is significantly enhanced across the HDL, probably due to the triggering. Finally, we measure the 3D rms Mach Number as a function of position and find a correlation between the Mach number and the CFE within the HDL only. This correlation is interpreted as due to feedback from the newly-formed stars and a change in its slope between the three main star-forming regions is construed as another evolutionary effect. We conclude that triggering has affected the star-formation process in the W3 GMC primarily by creating additional dense structures that can collapse into stars. Any traces of changes in CFE due to additional turbulence have since been overruled by the feedback effects of the star-forming process itself.Comment: 14 pages, 11 figures, 1 table, accepted for publication in MNRA

Personality characteristics of Greek mothers of children with special needs who are involved in special needs support centres

It is generally accepted that support of the family is critical for effective intervention in the case of a child with special educational needs (SEN). The quality of this support highly depends on the personality characteristics and the mental health of the parents. It has also been argued that, because of the increased pressure and the strain of having to care for a child with SEN, the opportunity to learn from and share problems with other families is very beneficial. It is also essential to seek emotional support at times of crisis through the means of parent support groups. This empirical study focuses on the mothers' personality since they are more directly affected by their child's disability. The aim of the study was to examine whether participation in parent support groups and sharing with others the care of a child with SEN affect the self-esteem, the coping mechanisms and the depression of mothers with such children.peer-reviewe

Introspection confidence predicts EEG decoding of self-generated thoughts and meta-awareness

The neurophysiological bases of mind wandering (MW) – an experiential state wherein attention is disengaged from the external environment in favour of internal thoughts, and state meta-awareness are poorly understood. In parallel, the relationship between introspection confidence in experiential state judgements and neural representations remains unclear. Here, we recorded EEG whilst participants completed a listening task within which they made experiential state judgments and rated their confidence. Alpha power was reliably greater during MW episodes, with unaware MW further associated with greater delta and theta power. Multivariate pattern classification analysis revealed that MW, and meta-awareness can be decoded from the distribution of power in these three frequency bands. Critically, we show that individual decoding accuracies positively correlate with introspection confidence. Our results reaffirm the role of alpha oscillations in MW, implicate lower frequencies in meta-awareness, and are consistent with the proposal that introspection confidence indexes neurophysiological discriminability of representational states

OCCUPATIONAL STRESS, DEPRESSION AND JOB SATISFACTION OF SPECIAL EDUCATION TEACHERS

Objective: The purpose of this study is to investigate occupational stress, depression and anxiety of primary education special education teachers, as well as levels of job satisfaction and how these are related to a number of demographic variables. Method: One hundred (100) special education teachers (39 males & 61 females) from the Regional Directorate of Attica took part in this study. Four self-report questionnaires were administered to the participants, i.e., the Perceived Stress Scale-14, the Depression Anxiety Stress-21, the Employee Satisfaction Inventory scale, and the Job Satisfaction Scale. A short health status questionnaire was also administered to the participants with questions related to the demographic data of the participants (gender, age, etc.), questions related to the work of the participants (level of education, years of service, etc.), as well as questions related to participants' health (e.g. "How good is your health?"). The statistical package SPSSv.21 was used for statistical analysis of the data. A variety of descriptive measures (frequency, percentages, mean, etc.) were used to describe the results. Pearson's linear correlation coefficient r was used to test the correlation between two variables. Additionally, the PROCESS macro (version 3) for SPSS was used in order to conduct moderation analysis. Results: The results showed that participants reported moderate levels of perceived stress, anxiety and depression, as well as levels of job satisfaction. Negative correlations between perceived stress and job satisfaction and between depression and job satisfaction were observed. Regarding stress and health status, elevated levels of stress were related to poorer health. Furthermore, correlations between stress, anxiety and depression with job satisfaction appeared to be influenced by gender, and in most cases the correlations had different directions between males and females. Therefore, occupational stress, depression and anxiety can be considered as predictors of the health status of special education teachers, as high levels of occupational stress and anxiety are strongly related to low levels of self-reported health-well-being, satisfaction. Conclusions: The results of this study highlight the need to explore the mental health of special education needs teachers that are associated with specific physical health issues so that measures can be taken for the development of prevention programs and personal strategies in order to cope with stress, anxiety and depression in teachers. Article visualizations

Response time fluctuations in the sustained attention to response task predict performance accuracy and meta-awareness of attentional states

Previous research suggests that response time (RT) patterns in the Sustained Attention to Response Task(SART) differentially predict different features of mind wandering but it is unknown how they relate to meta-awareness of attentional states. We applied principal component analysis to blocks of non-target (go) trials prior to target(no-go) trials and attentional state and meta-awareness probes in the SART and identified three distinct patterns that replicated those observed in previous research. A stable response rate was associated with superior target performance, whereas RT acceleration prior to targets was associated with poorer target performance. Self-reported attentional state was not significantly predicted by any of the pattern components. By contrast, meta-awareness was independently associated with two distinct RT fluctuation patterns with evidence that each pattern was specifically related to either meta-awareness of off-task or on-task states. These results suggest that mind wandering and meta-awareness of attentional states have distinct and overlapping imprints on RT patterns in the SART. We conclude by highlighting implications of these results for introspective methods and the measurement of mind wandering

Two Mass Distributions in the L 1641 Molecular Clouds: The Herschel Connection of Dense Cores and Filaments in Orion A

We present Herschel survey maps of the L 1641 molecular clouds in Orion A. We extracted both the filaments and dense cores in the region. We identified which of the dense sources are proto- or pre-stellar, and studied their association with the identified filaments. We find that although most (71%) of the pre-stellar sources are located on filaments there, is still a significant fraction of sources not associated with such structures. We find that these two populations (on and off the identified filaments) have distinctly different mass distributions. The mass distribution of the sources on the filaments is found to peak at 4 M_☉ and drives the shape of the core mass function (CMF) at higher masses, which we fit with a power law of the form dN/dlogM∝M^(–1.4 ± 0.4). The mass distribution of the sources off the filaments, on the other hand, peaks at 0.8 M_☉ and leads to a flattening of the CMF at masses lower than ~4 M_☉. We postulate that this difference between the mass distributions is due to the higher proportion of gas that is available in the filaments, rather than in the diffuse cloud

Oxygen depletion in giant planets with different formation histories

The atmospheric C/O ratio of exoplanets is widely used to constrain their formation. To guarantee that the C/O ratio provides robust information, we need to accurately quantify the amount of C and O in exoplanetary atmospheres. In the case of O, water and carbon monoxide are generally studied as the two key carriers. However, oxygen is a very reactive element and does not bind with carbon; depending on the temperature, it also binds to refractory elements. Estimating the amount of oxygen bound to refractory elements is therefore critical for unbiased estimates of the C/O ratio. In this work, we investigate the oxygen deficit due to refractory elements and its effects on the atmospheric C/O ratio of giant exoplanets as a function of their metallicity and equilibrium temperature. We model the composition of planetary atmospheres assuming chemical equilibrium and using as input physically justified elemental mixtures arising from detailed planet formation simulations. Our results show how the interplay between the atmospheric temperature and non-solar abundances of oxygen and refractory elements can sequester large fractions of oxygen, introducing significant biases in evaluating the C/O ratio when this effect is not accounted for. We apply our results to the case of Jupiter in the Solar System and show how the currently estimated water abundance points to a true oxygen abundance that is four times the solar one

Do Girls and Boys Perceive Themselves as Equally Engaged in School? The Results of an International Study from 12 Countries

This study examined gender differences in student engagement and academic performance in school. Participants included 3420 students (7th, 8th, and 9th graders) from Austria, Canada, China, Cyprus, Estonia, Greece, Malta, Portugal, Romania, South Korea, the United Kingdom, and the United States. The results indicated that, compared to boys, girls reported higher levels of engagement in school andwere rated higher by their teachers in academic performance. Student engagement accounted for gender differences in academic performance, but gender did not moderate the associations among student engagement, academic performance, or contextual supports. Analysis of multiple-group structural equation modeling revealed that perceptions of teacher support and parent support, but not peer support, were related indirectly to academic performance through student engagement. This partial mediation model was invariant across gender. The findings from this study enhance the understanding about the contextual and personal factors associated with girls' and boys' academic performance around the world