The impact of metallicity and dynamics on the evolution of young star clusters

The early evolution of a dense young star cluster (YSC) depends on the intricate connection between stellar evolution and dynamical processes. Thus, N-body simulations of YSCs must account for both aspects. We discuss N-body simulations of YSCs with three different metallicities (Z=0.01, 0.1 and 1 Zsun), including metallicity-dependent stellar evolution recipes and metallicity-dependent prescriptions for stellar winds and remnant formation. We show that mass-loss by stellar winds influences the reversal of core collapse. In particular, the post-collapse expansion of the core is faster in metal-rich YSCs than in metal-poor YSCs, because the former lose more mass (through stellar winds) than the latter. As a consequence, the half-mass radius expands more in metal-poor YSCs. We also discuss how these findings depend on the total mass and on the virial radius of the YSC. These results give us a clue to understand the early evolution of YSCs with different metallicity.Comment: to appear in "Massive Young Star Clusters Near and Far: From the Milky Way to Reionization", 2013 Guillermo Haro Conference, Eds. Y. D. Mayya, D. Rosa-Gonzalez & E. Terlevich, INAOE and AMC. 4 pages, 2 figure

The ominous fate of exomoons around hot Jupiters in the high-eccentricity migration scenario

All the giant planets in the Solar system host a large number of natural satellites. Moons in extrasolar systems are difficult to detect, but a Neptune-sized exomoon candidate has been recently found around a Jupiter-sized planet in the Kepler-1625b system. Due to their relative ease of detection, hot Jupiters (HJs), which reside in close orbits around their host stars with a period of a few days, may be very good candidates to search for exomoons. It is still unknown whether the HJ population can host (or may have hosted) exomoons. One suggested formation channel for HJs is high-eccentricity migration induced by a stellar binary companion combined with tidal dissipation. Here, we investigate under which circumstances an exomoon can prevent or allow high-eccentricity migration of a HJ, and in the latter case, if the exomoon can survive the migration process. We use both semi-analytic arguments, as well as direct N-body simulations including tidal interactions. Our results show that massive exomoons are efficient at preventing high-eccentricity migration. If an exomoon does instead allow for planetary migration, it is unlikely that the HJ formed can host exomoons since the moon will either spiral on to the planet or escape from it during the migration process. A few escaped exomoons can become stable planets after the Jupiter has migrated, or by tidally migrating themselves. The majority of the exomoons end up being ejected from the system or colliding with the primary star and the host planet. Such collisions might none the less leave observable features, such as a debris disc around the primary star or exorings around the close-in giant

Can alexithymia be assessed through an interview in adolescents? The Toronto Structured Interview for Alexithymia: Reliability, concurrent validity, discriminant validity, and relationships with emotional-behavioral symptoms

Alexithymia is connected to adolescents' psychopathology, but the current methods of assessment present limitations. The Toronto Structured Interview for Alexithymia (TSIA) was developed to overcome the limits of the main used self-rating scale in adults, but no studies investigated its feasibility with adolescents. This study involved 95 community adolescents aged 12-19 years. Adolescents were assessed with the TSIA, the 20-item Toronto Alexithymia Scale (TAS-20), the Verbal Comprehension Index of the WISC-IV for verbal skills, and the Child Behavior Checklist and Youth Self Report for emotional-behavioral symptoms. The aims were to investigate the TSIA internal consistency, concurrent validity with the TAS-20, discriminant validity with participants' verbal skills, and relationships with emotional-behavioral symptoms. TSIA showed good internal consistency, concurrent validity with the TAS-20 (except for factor DDF), and independence by participants' verbal skills, but few relationships with emotional-behavioral symptoms. In conclusion, TSIA showed some good psychometric proprieties but little convergence with research findings obtained with the TAS-20, suggesting the need for further research to check the feasibility of using the TSIA with adolescents. Meanwhile, a precautionary multi-method assessment of alexithymia is recommended

Quaternary structure change as a mechanism for the regulation of thymidine kinase 1-like enzymes

SummaryThe human cytosolic thymidine kinase (TK) and structurally related TKs in prokaryotes play a crucial role in the synthesis and regulation of the cellular thymidine triphosphate pool. We report the crystal structures of the TK homotetramer from Thermotoga maritima in four different states: its apo-form, a binary complex with thymidine, as well as the ternary structures with the two substrates (thymidine/AppNHp) and the reaction products (TMP/ADP). In combination with fluorescence spectroscopy and mutagenesis experiments, our results demonstrate that ATP binding is linked to a substantial reorganization of the enzyme quaternary structure, leading to a transition from a closed, inactive conformation to an open, catalytic state. We hypothesize that these structural changes are relevant to enzyme function in situ as part of the catalytic cycle and serve an important role in regulating enzyme activity by amplifying the effects of feedback inhibitor binding

Disabled Beggars in Addis Ababa

This study brings together qualitative and quantitative data to better understand the lives of people with disabilities who beg in Ethiopia. It sets out to provide an initial understanding of the lives of disabled beggars with particular emphasis on determining social and economic factors, and sequences of events or patterns of behaviour that are common to people with disabilities who now work as beggars. Chapter 3 provides an overview of the demographic characteristics of the survey respondents, including their education and vocational training levels and work history. Additional attention was directed to identifying possible areas of intervention that might sever the links between disability and poverty. The study yielded an intriguing set of results that identify: the complex set of issues with which disabled beggars grapple; a series of points where targeted intervention by governments, UN agencies, NGOs and disabled people's organizations could help break the on-going cycle of disability and poverty; and choices that lead some men and women with disabilities to beg. The study contains recommendations for policy, programming and areas for further research

From emotional mutual to self-regulation in attention deficit/ hyperactivity disorder: A pilot study on a sample of preschool-age children and their parents

The present study aimed to verify the relationship between parent-child interaction characteristics and the ability of children with attention deficit/hyperactivity disorder (ADHD) to self-regulate their emotions. The sample included 60 participants: 20 mothers, 20 fathers, and 20 preschool-age males with a diagnosis of ADHD. Parents completed the 20-Item Toronto Alexithymia Scale. The Child Emotional Abilities Task was administered to the child and Autobiographical Emotional Events Dialogues were administered to mother-child and father-child dyads. Several characteristics of parent-child interactions, such as maternal ability to accept an active role of the child during the task, correlated with the child’s ability to identify and describe his own feelings. Parental abilities to involve the child in a reciprocal narrative and avoid boundary dissolution also correlated with the individual capability of the child in imaginative processes. In conclusion, parental emotional abilities were related to the ways in which parents interacted with their children with ADHD during an emotional task. The characteristics of these interactions were related to child emotional self-regulation abilities

Alexithymia and obesity: controversial findings from a multimethod assessment

OBJECTIVE: The aim of the study is to assess alexithymia levels in obese patients using a multimethod measurement (TAS-20 and TSIA) to evaluate both possible differences between the two instruments and their relationship with body weight. PATIENTS AND METHODS: 54 obese patients, seeking surgical treatment, were enrolled. They completed a socio-demographic questionnaire, 20-items Toronto Alexithymia Scale and the Toronto Structured Interview for Alexithymia. RESULTS: Data analysis showed a significant positive association between TAS-20 and TSIA total scores (r=.28, p<.05), but only the TSIA score was positively related to body weight (r=.39; p<.001). Multivariable linear regression models showed the predictive effects of TSIA total score (beta=.41; p<.001) and difficulty in identifying feelings (DIF) (beta=.56; p<.001) respectively on weight. CONCLUSIONS: The findings showed a different association between body weight and alexithymia according to the instrument employed to evaluate alexithymia, supporting the importance of a multimethod assessment in some clinical conditions

Symbolic-Numeric Algorithms for Computer Analysis of Spheroidal Quantum Dot Models

A computation scheme for solving elliptic boundary value problems with axially symmetric confining potentials using different sets of one-parameter basis functions is presented. The efficiency of the proposed symbolic-numerical algorithms implemented in Maple is shown by examples of spheroidal quantum dot models, for which energy spectra and eigenfunctions versus the spheroid aspect ratio were calculated within the conventional effective mass approximation. Critical values of the aspect ratio, at which the discrete spectrum of models with finite-wall potentials is transformed into a continuous one in strong dimensional quantization regime, were revealed using the exact and adiabatic classifications.Comment: 6 figures, Submitted to Proc. of The 12th International Workshop on Computer Algebra in Scientific Computing (CASC 2010) Tsakhkadzor, Armenia, September 5 - 12, 201

Measuring participation for persons with mental illness: A systematic review assessing relevance of existing scales for low and middle income countries

Background: Participation is increasingly becoming an important outcome for assessment in many fields, including development, disability and policy implementation. However, selecting specific instruments to measure participation has been a significant problem due to overlapping conceptual definitions and use of different theories. The objective of this paper is to identify participation instruments, examine theories/definition supporting their use and highlight scales for use in low and middle-income countries for persons with mental illness. Methods: A systematic literature review was conducted to identify instruments intended to measure participation for individuals with severe mental illness. The search was limited to peer-reviewed articles published in English between 2003 and 2014. Instruments that measured related concepts of well-being, quality of life and social functioning were also identified and screened for items that pertained to participation, defined as empowerment and collective capabilities. Results: Five scales met established criteria for assessing participation and were determined to contain questions measuring empowerment and/or collective capabilities. However, each scale largely assessed individual functioning and capacity, while neglecting collective aspects of the community. All scales were developed in high-income countries and none were used in low and middle-income countries. Conclusions: There is an urgent need for participation scales to focus on empowerment as well as collective capabilities. Further, development of participation scales should clearly delineate theoretical foundations and concepts used. Finally, participation scales used in low and middle income countries should consider how contextual factors like medicine, poverty and disability, particularly with regards to mental illness, impact content of the scale

Apparent diffusion coefficient assessment of brain development in normal fetuses and ventriculomegaly

Diffusion neuro-MRI has benefited significantly from sophisticated pre-processing procedures aimed at improving image quality and diagnostic. In this work, diffusion-weighted imaging (DWI) was used with artifact correction and the apparent diffusion coefficient (ADC) was quantified to investigate fetal brain development. The DWI protocol was designed in order to limit the acquisition time and to estimate ADC without perfusion bias. The ADC in normal fetal brains was compared to cases with isolated ventriculomegaly (VM), a common fetal disease whose DWI studies are still scarce. DWI was performed in 58 singleton fetuses (Gestational age (GA) range: 19–38w) at 1.5T. In 31 cases, VM was diagnosed on ultrasound. DW-Spin Echo EPI with b-values = 50, 200, 700 s/mm2 along three orthogonal axes was used. All images were corrected for noise, Gibbs-ringing, and motion artifacts. The signal-to-noise ratio (SNR) was calculated and the ADC was measured with a linear least-squared algorithm. A multi-way ANOVA was used to evaluate differences in ADC between normal and VM cases and between second and third trimester in different brain regions. Correlation between ADC and GA was assessed with linear and quadratic regression analysis. Noise and artifact correction considerably increased SNR and the goodness-of-fit. ADC measurements were significantly different between second and third trimester in centrum semiovale, frontal white matter, thalamus, cerebellum and pons of both normal and VM brains (p ≤ 0.03). ADC values were significantly different between normal and VM in centrum semiovale and frontal white matter (p ≤ 0.02). ADC values in centrum semiovale, thalamus, cerebellum and pons linearly decreased with GA both in normal and VM brains, while a quadratic relation with GA was found in basal ganglia and occipital white matter of normal brains and in frontal white matter of VM (p ≤ 0.02). ADC values in all fetal brain regions were lower than those reported in literature where DWI with b = 0 was performed. Conversely, they were in agreement with the results of other authors who measured perfusion and diffusion contributions separately. By optimizing our DWI protocol we achieved an unbiased quantification of brain ADC in reasonable scan time. Our findings suggested that ADC can be a useful biomarker of brain abnormalities associated with VM