74 research outputs found
Predicting trajectories of behavioral adjustment in children diagnosed with acute lymphoblastic leukemia
Purpose
Previous research showed that children with cancer are at risk for developing behavioral adjustment problems after successful treatment; however, the course of adjustment remains unclear. This study focuses on adjustment trajectories of children during treatment for acute lymphoblastic leukemia (ALL) and aims to distinguish subgroups of patients showing different trajectories during active treatment, and to identify sociodemographic, medical, and psychosocial predictors of the distinct adjustment trajectories.
Methods
In a multicenter longitudinal study, 108 parents of a child (response rate 80 %) diagnosed with ALL were assessed during induction treatment (T0), after induction/consolidation treatment (T1), and after end of treatment (T2). Trajectories of child behavioral adjustment (Child Behavior Checklist; CBCL) were tested with latent class growth modeling (LCGM) analyses.
Results
For internalizing behavior, a three-trajectory model was found: a group that experienced no problems (60 %), a group that experienced only initial problems (30 %), and a group that experienced chronic problems (10 %). For externalizing behavior, a three-trajectory model was also found: a group that experienced no problems (83 %), a group that experienced chronic problems (12 %), and a group that experienced increasing problems (5 %). Only parenting stress and baseline QoL (cancer related) were found to contribute uniquely to adjustment trajectories.
Conclusions
The majority of the children (77 %) showed no or transient behavioral problems during the entire treatment as reported by parents. A substantial group (23 %) shows maladaptive trajectories of internalizing behavioral problems and/or externalizing behavioral problems. Screening for risk factors for developing problems might be helpful in early identification of these children
Galaxy Zoo: Reproducing Galaxy Morphologies Via Machine Learning
We present morphological classifications obtained using machine learning for
objects in SDSS DR6 that have been classified by Galaxy Zoo into three classes,
namely early types, spirals and point sources/artifacts. An artificial neural
network is trained on a subset of objects classified by the human eye and we
test whether the machine learning algorithm can reproduce the human
classifications for the rest of the sample. We find that the success of the
neural network in matching the human classifications depends crucially on the
set of input parameters chosen for the machine-learning algorithm. The colours
and parameters associated with profile-fitting are reasonable in separating the
objects into three classes. However, these results are considerably improved
when adding adaptive shape parameters as well as concentration and texture. The
adaptive moments, concentration and texture parameters alone cannot distinguish
between early type galaxies and the point sources/artifacts. Using a set of
twelve parameters, the neural network is able to reproduce the human
classifications to better than 90% for all three morphological classes. We find
that using a training set that is incomplete in magnitude does not degrade our
results given our particular choice of the input parameters to the network. We
conclude that it is promising to use machine- learning algorithms to perform
morphological classification for the next generation of wide-field imaging
surveys and that the Galaxy Zoo catalogue provides an invaluable training set
for such purposes.Comment: 13 Pages, 5 figures, 10 tables. Accepted for publication in MNRAS.
Revised to match accepted version
Galaxy Zoo: the dependence of morphology and colour on environment
We analyse the relationships between galaxy morphology, colour, environment
and stellar mass using data for over 100,000 objects from Galaxy Zoo, the
largest sample of visually classified morphologies yet compiled. We
conclusively show that colour and morphology fractions are very different
functions of environment. Both are sensitive to stellar mass; however, at fixed
stellar mass, while colour is also highly sensitive to environment, morphology
displays much weaker environmental trends. Only a small part of both relations
can be attributed to variation in the stellar mass function with environment.
Galaxies with high stellar masses are mostly red, in all environments and
irrespective of their morphology. Low stellar-mass galaxies are mostly blue in
low-density environments, but mostly red in high-density environments, again
irrespective of their morphology. The colour-density relation is primarily
driven by variations in colour fractions at fixed morphology, in particular the
fraction of spiral galaxies that have red colours, and especially at low
stellar masses. We demonstrate that our red spirals primarily include galaxies
with true spiral morphology. We clearly show there is an environmental
dependence for colour beyond that for morphology. Before using the Galaxy Zoo
morphologies to produce the above results, we first quantify a luminosity-,
size- and redshift-dependent classification bias that affects this dataset, and
probably most other studies of galaxy population morphology. A correction for
this bias is derived and applied to produce a sample of galaxies with reliable
morphological type likelihoods, on which we base our analysis.Comment: 25 pages, 20 figures (+ 6 pages, 11 figures in appendices);
moderately revised following referee's comments; accepted by MNRA
Echoes from Ancient Supernovae in the Large Magellanic Cloud
In principle, the light from historical supernovae could still be visible as
scattered-light echoes even centuries later. However, while echoes have been
discovered around some nearby extragalactic supernovae well after the
explosion, targeted searches have not recovered any echoes in the regions of
historical Galactic supernovae. The discovery of echoes can allow us to
pinpoint the supernova event both in position and age and, most importantly,
allow us to acquire spectra of the echo light to type the supernova centuries
after the direct light from the explosion first reached the Earth. Here we
report on the discovery of three faint new variable surface brightness
complexes with high apparent proper motion pointing back to well-defined
positions in the Large Magellanic Cloud (LMC). These positions correspond to
three of the six smallest (and likely youngest) previously catalogued supernova
remnants, and are believed to be due to thermonuclear (Type Ia) supernovae.
Using the distance and proper motions of these echo arcs, we estimate ages of
610 and 410 yr for the echoes #2 and #3.Comment: 13 pages, 3 figures, 1 table. PDF format. Note: This paper has been
accepted by Nature for publication as a letter. It is embargoed for
discussion in the popular press until publication in Natur
Galaxy Zoo: Passive Red Spirals
We study the spectroscopic properties and environments of red spiral galaxies
found by the Galaxy Zoo project. By carefully selecting face-on, disk dominated
spirals we construct a sample of truly passive disks (not dust reddened, nor
dominated by old stellar populations in a bulge). As such, our red spirals
represent an interesting set of possible transition objects between normal blue
spirals and red early types. We use SDSS data to investigate the physical
processes which could have turned these objects red without disturbing their
morphology. Red spirals prefer intermediate density regimes, however there are
no obvious correlations between red spiral properties and environment -
environment alone is not sufficient to determine if a spiral will become red.
Red spirals are a small fraction of spirals at low masses, but are a
significant fraction at large stellar masses - massive galaxies are red
independent of morphology. We confirm that red spirals have older stellar popns
and less recent star formation than the main spiral population. While the
presence of spiral arms suggests that major star formation cannot have ceased
long ago, we show that these are not recent post-starbursts, so star formation
must have ceased gradually. Intriguingly, red spirals are ~4 times more likely
than normal spirals to host optically identified Seyfert or LINER, with most of
the difference coming from LINERs. We find a curiously large bar fraction in
the red spirals suggesting that the cessation of star formation and bar
instabilities are strongly correlated. We conclude by discussing the possible
origins. We suggest they may represent the very oldest spiral galaxies which
have already used up their reserves of gas - probably aided by strangulation,
and perhaps bar instabilities moving material around in the disk.Comment: MNRAS in press, 20 pages, 15 figures (v3
Galaxy Zoo: The Environmental Dependence of Bars and Bulges in Disc Galaxies
We present an analysis of the environmental dependence of bars and bulges in
disc galaxies, using a volume-limited catalogue of 15810 galaxies at z<0.06
from the Sloan Digital Sky Survey with visual morphologies from the Galaxy Zoo
2 project. We find that the likelihood of having a bar, or bulge, in disc
galaxies increases when the galaxies have redder (optical) colours and larger
stellar masses, and observe a transition in the bar and bulge likelihoods, such
that massive disc galaxies are more likely to host bars and bulges. We use
galaxy clustering methods to demonstrate statistically significant
environmental correlations of barred, and bulge-dominated, galaxies, from
projected separations of 150 kpc/h to 3 Mpc/h. These environmental correlations
appear to be independent of each other: i.e., bulge-dominated disc galaxies
exhibit a significant bar-environment correlation, and barred disc galaxies
show a bulge-environment correlation. We demonstrate that approximately half
(50 +/- 10%) of the bar-environment correlation can be explained by the fact
that more massive dark matter haloes host redder disc galaxies, which are then
more likely to have bars. Likewise, we show that the environmental dependence
of stellar mass can only explain a small fraction (25 +/- 10%) of the
bar-environment correlation. Therefore, a significant fraction of our observed
environmental dependence of barred galaxies is not due to colour or stellar
mass dependences, and hence could be due to another galaxy property. Finally,
by analyzing the projected clustering of barred and unbarred disc galaxies with
halo occupation models, we argue that barred galaxies are in slightly
higher-mass haloes than unbarred ones, and some of them (approximately 25%) are
satellite galaxies in groups. We also discuss implications about the effects of
minor mergers and interactions on bar formation.Comment: 20 pages, 18 figures; references updated; published in MNRA
A European research agenda for somatic symptom disorders, bodily distress disorders, and functional disorders: Results of an estimate-talk-estimate delphi expert study
Background: Somatic Symptom Disorders (SSD), Bodily Distress Disorders (BDD) and functional disorders (FD) are associated with high medical and societal costs and pose a substantial challenge to the population and health policy of Europe. To meet this challenge, a specific research agenda is needed as one of the cornerstones of sustainable mental health research and health policy for SSD, BDD, and FD in Europe. Aim: To identify the main challenges and research priorities concerning SSD, BDD, and FD from a European perspective. Methods: Delphi study conducted from July 2016 until October 2017 in 3 rounds with 3 workshop meetings and 3 online surveys, involving 75 experts and 21 European countries. EURONET-SOMA and the European Association of Psychosomatic Medicine (EAPM) hosted the meetings. Results: Eight research priorities were identified: (1) Assessment of diagnostic profiles relevant to course and treatment outcome. (2) Development and evaluation of new, effective interventions. (3) Validation studies on questionnaires or semi-structured interviews that assess chronic medical conditions in this context. (4) Research into patients preferences for diagnosis and treatment. (5) Development of new methodologic designs to identify and explore mediators and moderators of clinical course and treatment outcomes (6). Translational research exploring how psychological and somatic symptoms develop from somatic conditions and biological and behavioral pathogenic factors. (7) Development of new, effective interventions to personalize treatment. (8) Implementation studies of treatment interventions in different settings, such as primary care, occupational care, general hospital and specialty mental health settings. The general public and policymakers will benefit from the development of new, effective, personalized interventions for SSD, BDD, and FD, that will be enhanced by translational research, as well as from the outcomes of research into patient involvement, GP-patient communication, consultation-liaison models and implementation. Conclusion: Funding for this research agenda, targeting these challenges in coordinated research networks such as EURONET-SOMA and EAPM, and systematically allocating resources by policymakers to this critical area in mental and physical well-being is urgently needed to improve efficacy and impact for diagnosis and treatment of SSD, BDD, and FD across Europe
Targeting a Subpocket in Trypanosoma brucei Phosphodiesterase B1 (TbrPDEB1) Enables the Structure-Based Discovery of Selective Inhibitors with Trypanocidal Activity
Several trypanosomatid cyclic nucleotide phosphodiesterases (PDEs) possess a unique, parasite-specific cavity near the ligand-binding region that is referred to as the P-pocket.
One of these enzymes, Trypanosoma brucei PDE B1 (TbrPDEB1), is considered a drug target for the treatment of African sleeping sickness. Here, we elucidate the molecular
determinants of inhibitor binding and reveal that the P-pocket is amenable to directed design. By iterative cycles of design, synthesis, and pharmacological evaluation and by elucidating the structures of inhibitor-bound TbrPDEB1, hPDE4B, and hPDE4D complexes, we have developed 4a,5,8,8a-tetrahydrophthalazinones as the first selective TbrPDEB1 inhibitor series. Two of these, 8 (NPD-008) and 9 (NPD-039), were potent (Ki = 100 nM) TbrPDEB1 inhibitors with antitrypanosomal effects (IC50 = 5.5 and 6.7 ?M, respectively). Treatment of parasites with 8 caused an increase in intracellular cyclic adenosine monophosphate (cAMP) levels and severe disruption of T. brucei cellular organization, chemically validating trypanosomal PDEs as therapeutic targets in trypanosomiasis
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