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

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

Sideromimic Modification of Lactivicin Dramatically Increases Potency against Extensively Drug-Resistant <i>Stenotrophomonas maltophilia </i>Clinical Isolates

Acetamido derivatives of the naturally antibacterial non-β-lactam lactivicin (LTV) have improved activity against their penicillin binding protein targets and reduced hydrolysis by β-lactamases, but penetration into Gram-negative bacteria is still relatively poor. Here we report that modification of the LTV lactone with a catechol-type siderophore increases potency 1,000-fold against Stenotrophomonas maltophilia, a species renowned for its insusceptibility to antimicrobials. The MIC90 of modified lactone compound 17 (LTV17) against a global collection of extensively drug-resistant clinical S. maltophilia isolates was 0.063 μg · ml(-1) Sideromimic modification does not reduce the ability of LTVs to induce production of the L1 and L2 β-lactamases in S. maltophilia and does not reduce the rate at which LTVs are hydrolyzed by L1 or L2. We conclude, therefore, that lactivicin modification with a siderophore known to be preferentially used by S. maltophilia substantially increases penetration via siderophore uptake. LTV17 has the potential to be developed as a novel antimicrobial for treatment of infections by S. maltophilia More generally, our work shows that sideromimic modification in a species-targeted manner might prove useful for the development of narrow-spectrum antimicrobials that have reduced collateral effects

ALMA reveals the aftermath of a white dwarf–brown dwarf merger in CK Vulpeculae

We present Atacama Large Millimeter–Submillimeter Array (ALMA) observations of CK Vulpeculae which is identified with “Nova Vulpeculae 1670”. They trace obscuring dust in the inner regions of the associated nebulosity. The dust forms two cocoons, each extending ∼5″ north and south of the presumed location of the central star. Brighter emission is in a more compact east–west structure (2″ × 1″) where the cocoons intersect. We detect line emission in NH2CHO, CN, four organic molecules and C17O. CN lines trace bubbles within the dusty cocoons; CH3OH a north–south S–shaped jet; and other molecules a central cloud with a structure aligned with the innermost dust structure. The major axis of the overall dust and gas bubble structure has a projected inclination of ∼24° with respect to a 71″ extended “hourglass” nebulosity, previously seen in Hα. Three cocoon limbs align with dark lanes in the inner regions of the same Hα images. The central 2″ × 1″ dust is resolved into a structure consistent with a warped dusty disc. The velocity structure of the jets indicates an origin at the centre of this disc and precession with an unknown period. Deceleration regions at both the northern and southern tips of the jets are roughly coincident with additional diffuse dust emission over regions approximately 2″ across. These structures are consistent with a bipolar outflow expanding into surrounding high density material. We suggest that a white dwarf and brown dwarf merged between 1670 and 1672, with the observed structures and extraordinary isotopic abundances generated as a result

Statistical properties of 12.2 GHz methanol masers associated with a complete sample of 6.7 GHz methanol masers

We present definitive detection statistics for 12.2 GHz methanol masers towards a complete sample of 6.7 GHz methanol masers detected in the Methanol Multibeam survey south of declination -20 degrees. In total, we detect 250 12.2 GHz methanol masers towards 580 6.7 GHz methanol masers. This equates to a detection rate of 43.1%, which is lower than that of previous significant searches of comparable sensitivity. Both the velocity ranges and the flux densities of the target 6.7 GHz sources surpass that of their 12.2 GHz companion in almost all cases. 80 % of the detected 12.2 GHz methanol maser peaks are coincident in velocity with the 6.7 GHz maser peak. Our data support an evolutionary scenario whereby the 12.2 GHz sources are associated with a somewhat later evolutionary stage than the 6.7 GHz sources devoid of this transition. Furthermore, we find that the 6.7 GHz and 12.2 GHz methanol sources increase in luminosity as they evolve. In addition to this, evidence for an increase in velocity range with evolution is presented. This implies that it is not only the luminosity, but also the volume of gas conducive to the different maser transitions, that increases as the sources evolve. Comparison with GLIMPSE mid-infrared sources has revealed a coincidence rate between the locations of the 6.7 GHz methanol masers and GLIMPSE point sources similar to that achieved in previous studies. Overall, the properties of the GLIMPSE sources with and without 12.2 GHz counterparts are similar. There is a higher 12.2 GHz detection rate towards those 6.7 GHz methanol masers that are coincident with extended green objects.Comment: Accepted to ApJ March 2011. 28 pages, 9 figure

Cargo Cults in Information Systems Development: a Definition and an Analytical Framework

Organizations today adopt agile information systems development methods (ISDM), but many do not succeed with the adoption process and in achieving desired results. Systems developers sometimes fail in efficient use of ISDM, often due to a lack of understanding the fundamental intentions of the chosen method. In many cases organizations simply imitate the behavior of others without really understanding why. This conceptual paper defines this phenomenon as an ISDM cargo cult behavior and proposes an analytical framework to identify such situations. The concept of cargo cults originally comes from the field of social anthropology and has been used to explain irrational, ritualistic imitation of certain behavior. By defining and introducing the concept in the field of information systems development we provide a diagnostic tool to better understand one of the reasons why ISDM adoption sometimes fail