Tightening the belt: Constraining the mass and evolution in SDC335

Recent ALMA observations identified one of the most massive star-forming cores yet observed in the Milky Way; SDC335-MM1, within the infrared dark cloud SDC335.579-0.292. Along with an accompanying core MM2, SDC335 appears to be in the early stages of its star formation process. In this paper we aim to constrain the properties of the stars forming within these two massive millimetre sources. Observations of SDC335 at 6, 8, 23 and 25GHz were made with the ATCA. We report the results of these continuum measurements, which combined with archival data, allow us to build and analyse the spectral energy distributions (SEDs) of the compact sources in SDC335. Three HCHII regions within SDC335 are identified, two within the MM1 core. For each HCHII region, a free-free emission curve is fit to the data allowing the derivation of the sources' emission measure, ionising photon flux and electron density. Using these physical properties we assign each HCHII region a ZAMS spectral type, finding two protostars with characteristics of spectral type B1.5 and one with a lower limit of B1-B1.5. Ancillary data from infrared to mm wavelength are used to construct free-free component subtracted SEDs for the mm-cores, allowing calculation of the bolometric luminosities and revision of the previous gas mass estimates. The measured luminosities for the two mm-cores are lower than expected from accreting sources displaying characteristics of the ZAMS spectral type assigned to them. The protostars are still actively accreting, suggesting that a mechanism is limiting the accretion luminosity, we present the case for two different mechanisms capable of causing this. Finally, using the ZAMS mass values as lower limit constraints, a final stellar population for SDC335 was synthesised finding SDC335 is likely to be in the process of forming a stellar cluster comparable to the Trapezium Cluster and NGC6334 I(N).Comment: 10 pages, 5 figures. Accepted for publication in A&

The very fast evolution of Sakurai's object

V4334 Sgr (a.k.a. Sakurai's object) is the central star of an old planetary nebula that underwent a very late thermal pulse a few years before its discovery in 1996. We have been monitoring the evolution of the optical emission line spectrum since 2001. The goal is to improve the evolutionary models by constraining them with the temporal evolution of the central star temperature. In addition the high resolution spectral observations obtained by X-shooter and ALMA show the temporal evolution of the different morphological components.Comment: 2 pages, 2 figures to appear in the Proceedings of the IAU Symp. 323: "Planetary nebulae: Multi-wavelength probes of stellar and galactic evolution". Eds. X.-W. Liu, L. Stanghellini and A. Karaka

Mental health benefits of interactions with nature in children and teenagers: a systematic review

Background It is commonly believed that nature has positive impacts on children’s health, including physical, mental and social dimensions. This review focuses on how accessibility to, exposure to and engagement with nature affects the mental health of children and teenagers. Methods Ten academic databases were used to systematically search and identify primary research papers in English or French from 1990 to 1 March 2017. Papers were included for review based on their incorporation of nature, children and teenagers (0–18 years), quantitative results and focus on mental health. Results Of the 35 papers included in the review, the majority focused on emotional well-being and attention deficit disorder/hyperactivity disorder. Other outcome measures included overall mental health, self-esteem, stress, resilience, depression and health-related quality of life. About half of all reported findings revealed statistically significant positive relationships between nature and mental health outcomes and almost half reported no statistical significance. Conclusions Findings support the contention that nature positively influences mental health; however, in most cases, additional research with more rigorous study designs and objective measures of both nature and mental health outcomes are needed to confirm statistically significant relationships. Existing evidence is limited by the cross-sectional nature of most papers

Novel mechanisms of efflux-mediated levofloxacin resistance and reduced amikacin susceptibility in Stenotrophomonas maltophilia

Fluoroquinolone resistance in Stenotrophomonas maltophilia is multifactorial, but the most significant factor is overproduction of efflux pumps, particularly SmeDEF, following mutation. Here, we report that mutations in the glycosyl transferase gene smlt0622 in S. maltophilia K279a mutant K M6 cause constitutive activation of SmeDEF production, leading to elevated levofloxacin MIC. Selection of a levofloxacin-resistant K M6 derivative, K M6 LEV(r), allowed identification of a novel two-component regulatory system, Smlt2645/6 (renamed SmaRS). The sensor kinase Smlt2646 (SmaS) is activated by mutation in K M6 LEV(r) causing overproduction of two novel ABC transporters and the known aminoglycoside efflux pump SmeYZ. Overproduction of one ABC transporter, Smlt1651-4 (renamed SmaCDEF), causes levofloxacin resistance in K M6 LEV(r). Overproduction of the other ABC transporter, Smlt2642/3 (renamed SmaAB), and SmeYZ both contribute to the elevated amikacin MIC against K M6 LEV(r). Accordingly, we have identified two novel ABC transporters associated with antimicrobial drug resistance in S. maltophilia and two novel regulatory systems whose mutation causes resistance to levofloxacin, clinically important as a promising drug for monotherapy against this highly resistant pathogen

Prevalence and trajectories of depressive symptoms in mothers of children with newly diagnosed epilepsy

Purpose: To examine the prevalence, trajectories, and predictors of depressive symptoms (DS) in mothers of children with new-onset epilepsy. Methods: A sample of 339 mothers was analyzed from the health-related quality of life in children with epilepsy study assessed four times during the first 24 months after diagnosis. Mothers\u27 DS were measured using the Center for Epidemiological Studies Depression Scale. Trajectories of DS were investigated using group-based trajectory modeling, and maternal, child, and family factors were compared across groups using analysis of variance (ANOVA) and chi square tests. Multinomial logistic regression identified predictors of DS trajectories. Key Findings: A total of 258 mothers completed the study. Prevalence of depression ranged from 30-38% across four times within the first 24 months after their child\u27s diagnosis. Four trajectories of DS were observed: low stable (59%), borderline (25%), moderate increasing (9%), and high decreasing (7%). Using the low stable group as the reference group, the borderline group was younger, had worse family functioning, and fewer family resources; the moderate increasing group was younger, had children with cognitive problems, worse family functioning, and more family demands; and the high decreasing group had less education and children with lower quality of life. Significance: Risk for clinical depression is common among mothers of children with new-onset epilepsy. These mothers are not homogenous, but consist of groups with different trajectories and predictors of DS. Child\u27s cognitive problems was the strongest predictor identified; epilepsy severity did not predict DS trajectory. Health care professionals should consider routinely assessing maternal depression during clinic visits for pediatric epilepsy. © 2010 International League Against Epilepsy

The impact of maternal depressive symptoms on health-related quality of life in children with epilepsy: A prospective study of family environment as mediators and moderators

Purpose: To examine the impact of maternal depressive symptoms (DS) on health-related quality of life (HRQL) in children with new-onset epilepsy and to identify family factors that moderate and mediate this relationship during the first 24 months after epilepsy diagnosis. Methods: A sample of 339 mother-child dyads recruited from pediatric neurologists across Canada in the Health-related Quality of Life in Children with Epilepsy Study. Mothers\u27 and neurologists\u27 reports were collected at four times during the 24-month follow-up. Mothers\u27 DS were measured using the Center for Epidemiological Studies Depression Scale (CES-D) and children\u27s HRQL using the Quality of Life in Childhood Epilepsy (QOLCE). Data were modeled using individual growth curve modeling. Key Findings: Maternal DS were observed to have a negative impact on QOLCE scores at 24 months (β = -0.47, p \u3c 0.0001) and the rate of change in QOLCE scores during follow-up (β = -0.04, p = 0.0250). This relationship was moderated by family resources (β = 0.25, p = 0.0243), and the magnitude of moderation varied over time (β = 0.09, p = 0.0212). Family functioning and demands partially mediated the impact of maternal DS on child HRQL (β = -0.07, p = 0.0007; β = -0.12, p = 0.0006). Significance: Maternal DS negatively impact child HRQL in new-onset epilepsy during the first 24 months after diagnosis. This relationship is moderated by family resources and mediated by family functioning and demands. By adopting family centered approaches, health care professionals may be able to intervene at the maternal or family level to promote more positive outcomes in children. © 2010 International League Against Epilepsy