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To assess differences in cognition functions and gross brain structure in children seven years after an episode of severe acute malnutrition (SAM), compared with other Malawian children.
Prospective longitudinal cohort assessing school grade achieved and results of five computer-based (CANTAB) tests, covering three cognitive domains. A subset underwent brain MRI scans which were reviewed using a standardized checklist of gross abnormalities and compared with a reference population of Malawian children.
Children discharged from SAM treatment in 2006 and 2007 (n 320; median age 9·3 years) were compared with controls: siblings closest in age to the SAM survivors and age/sex-matched community children.
SAM survivors were significantly more likely to be in a lower grade at school than controls (adjusted OR = 0·4; 95 % CI 0·3, 0·6; P < 0·0001) and had consistently poorer scores in all CANTAB cognitive tests. Adjusting for HIV and socio-economic status diminished statistically significant differences. There were no significant differences in odds of brain abnormalities and sinusitis between SAM survivors (n 49) and reference children (OR = 1·11; 95 % CI 0·61, 2·03; P = 0·73).
Despite apparent preservation in gross brain structure, persistent impaired school achievement is likely to be detrimental to individual attainment and economic well-being. Understanding the multifactorial causes of lower school achievement is therefore needed to design interventions for SAM survivors to thrive in adulthood. The cognitive and potential economic implications of SAM need further emphasis to better advocate for SAM prevention and early treatment.
Recent evidence suggests that exercise plays a role in cognition and that the posterior cingulate cortex (PCC) can be divided into dorsal and ventral subregions based on distinct connectivity patterns.
To examine the effect of physical activity and division of the PCC on brain functional connectivity measures in subjective memory complainers (SMC) carrying the epsilon 4 allele of apolipoprotein E (APOE 4) allele.
Participants were 22 SMC carrying the APOE ɛ4 allele (ɛ4+; mean age 72.18 years) and 58 SMC non-carriers (ɛ4–; mean age 72.79 years). Connectivity of four dorsal and ventral seeds was examined. Relationships between PCC connectivity and physical activity measures were explored.
ɛ4+ individuals showed increased connectivity between the dorsal PCC and dorsolateral prefrontal cortex, and the ventral PCC and supplementary motor area (SMA). Greater levels of physical activity correlated with the magnitude of ventral PCC–SMA connectivity.
The results provide the first evidence that ɛ4+ individuals at increased risk of cognitive decline show distinct alterations in dorsal and ventral PCC functional connectivity.
During the 1992–1993 observing season, WR3, 6, 16, 40, 66, 82 and 134 were monitored in fast photometry mode with time-resolution 0.005—0.01 s. Only WR6 reveals a possible period of P = 0.11 s (semi-amplitude A = 0.025 mag), which is close to the derived equilibrium period of a new-born pulsar in a binary system after the rapid phase of Roche Lobe Over-Flow from the original secondary component.
The bright star Sk—67°18 (Brey 5) in the Large Magellanic Cloud (LMC) contains an eclipsing binary system. Our radial velocity study reveals that the orbital period is almost exactly two days. The spectra also show that the star's primary component is not of spectral type WN, but that the star is rather an Of+O type binary where the primary is probably of type O3f*. Furthermore, Sk—67°18 appears to be a high-mass multiple system.
Deep Hβ narrowband and broadband images of M3 have been electronically blinked to search for cataclysmic binaries. Tests of the method on a known, faint cataclysmic enable us to set limits on the sensitivity of the technique. No bright (MB < 6) emission-line (equivalent width > 12 Å) cataclysmic binaries exist in M3 between 4 and 30 core radii from the center. Low luminosity globular X-ray sources could still be weak-lined (E.W. < 12 Å) and bright (MB ≃ +5 like some old novae) or strong-lined (E.W. ≃ 60 Å) and faint (MB > 7 like dwarf novae).
After CQ Cep, the system CX Cep has the shortest orbital period known among Galactic WR+O binaries. However, no definitive spectroscopic study is yet available for CX Cep, probably because of its relatively faint magnitude (B ≈ 13). We have therefore obtained and analyzed some 60 CCD spectra (3700-4900 Å, S/N ⋍ 100, 5 Å/2 pixels) in August and October 1987.
We have obtained some 15 CCD spectra at different orbital phases for each of the SBl systems HD193928 (WN6), HD197406 (WN7), and CQ Cep (WN7), in an attempt to detect the companion, determine its orbit and estimate the masses. The wavelength range of the spectra is λλ3600 - 4200Å, with 1.4Å/pixel and < S/N > ≈ 100/pixel. We compare the best emission-line (N IV λ4058Å) with the best absorption-line (H9 λ3835Å).
EZ CMa (HD 50896, WN5) is an enigmatic object. New photometry and polarimetry of EZ CMa are presented in the figure. Again the 3.77 day period is found but, as observed at previous epochs (e.g. Drissen et ai. 1989, Ap. J., 343, 426), the shapes of the curves change. The new photometry can also be interpreted in terms of a shorter period, of 1.254 days. A period of about one day is also claimed in other sets of photometric data (e.g. van der Hucht et ai., 1990, A. A., 228, 108) and in the IUE spectra of St.-Louis et ai. (1990, this symposium). However, despite the complex nature of the light curve, the 3.77 day period is strongly supported by the polarimetry, which shows no evidence for the shorter period.
Evidence is mounting that the dominant random component of variability in single WR stars can be explained by one common phenomenon: stochastic formation, propagation and decay of density enhancements in the winds.
We have recently used the PISCO and VATPOL Polarimeters at the MPI (Chile) and CASLEO (Argentina) 2.2 m telescopes to monitor over several weeks the brightest WR+O systems fainter than 9th magnitude in the Galaxy (V filter) and LMC/SMC (GaAs tube without filter). Each data point is accurate to ~ 0.02% in polarization P.
We present the observational signature of a statistically significant number of very massive stars around the core of R136 and discuss the evidence for dynamical processes to be responsible for their apparent location. Alternative scenarios are discussed as well.
Time-resolved spectroscopy has revealed small, systematically varying features superimposed on the broad emission lines of WR stars. We believe that these structures are due to inhomogeneities of emitting wind material propagating with the general wind. Here we suggest a common, but still unknown, origin for the intrinsic variations observed in WR stars.
We present a study of the star cluster associated with the massive Galactic HII region NGC 3603 based on near-IR broad- and narrowband observations taken with ISAAC/VLT under excellent seeing conditions (≤ 0.4″). We discuss color-color diagrams and address the impact of the high UV flux on the disk evolution of the low-mass stars.
The dependency of the Hβ-index on two physical parameters is briefly discussed. The previous calibration of Mv(β) (Fernie, 1965 or Crawford, 1971) is confirmed for main sequence O and B stars; however, the β-values of the later B-supergiants tend to be too large for their absolute magnitudes. The problem of filtering out stars with marginal emission is emphasized.
The objective is to determine the nature of the unseen companion of the single-lined spectroscopic binary, WR 148 (= WN7h+?). The absence of companion lines supports a compact companion (cc) scenario. The lack of hard X-rays favours a non-compact companion scenario. Is WR 148 a commonplace WR+OB binary or a rare WR+cc binary?
Eta Carinae is one of the most massive observable binaries. Yet determination of its orbital and physical parameters is hampered by obscuring winds. However the effects of the strong, colliding winds changes with phase due to the high orbital eccentricity. We wanted to improve measures of the orbital parameters and to determine the mechanisms that produce the relatively brief, phase-locked minimum as detected throughout the electromagnetic spectrum. We conducted intense monitoring of the He ii λ4686 line in η Carinae for 10 months in the year 2014, gathering ~300 high S/N spectra with ground- and space-based telescopes. We also used published spectra at the FOS4 SE polar region of the Homunculus, which views the minimum from a different direction. We used a model in which the He ii λ4686 emission is produced by two mechanisms: a) one linked to the intensity of the wind-wind collision which occurs along the whole orbit and is proportional to the inverse square of the separation between the companion stars; and b) the other produced by the ‘bore hole’ effect which occurs at phases across the periastron passage. The opacity (computed from 3D SPH simulations) as convolved with the emission reproduces the behavior of equivalent widths both for direct and reflected light. Our main results are: a) a demonstration that the He ii λ4686 light curve is exquisitely repeatable from cycle to cycle, contrary to previous claims for large changes; b) an accurate determination of the longitude of periastron, indicating that the secondary star is ‘behind’ the primary at periastron, a dispute extended over the past decade; c) a determination of the time of periastron passage, at ~4 days after the onset of the deep light curve minimum; and d) show that the minimum is simultaneous for observers at different lines of sight, indicating that it is not caused by an eclipse of the secondary star, but rather by the immersion of the wind-wind collision interior to the inner wind of the primary.
ι Orionis is a massive binary system consisting of O9III + B1 III/IV stars. Though the system has been well studied, much about its fundamental properties have been difficult to determine. In this paper we report on the discovery of the heartbeat phenomenon in ι Orionis making it the most massive heartbeat system currently known. Using this phenomenon we have found empirical values for the masses and radii of both components. Moreover, we report the detection of tidally induced oscillations in an O-type star for the first time. These discoveries open a new avenue for exploring asteroseismology in massive stars.
Despite aggressive multimodal therapy, human glioblastoma (hGBM), a highly malignant grade IV astrocytic tumour, remains incurable and inevitably relapses. Recent data has implicated intratumoral heterogeneity as the driver of therapy resistance and tumour relapse in hGBM. Thus models that capture the evolving hGBM biology in response to chemoradiotherapy will allow for the identification of cellular pathways that govern GBM therapy failure. In this study, we have developed a novel model to profile the clonal evolution of treatment naïve brain tumour initiating cell (BTIC) enriched hGBMs through chemoradiotherapy using: stem cell assays, BTIC marker expression and transcriptome analysis, immunohistochemistry, and cellular DNA barcoding technology. We report that treatment of hGBM BTICs leads to increased self-renewal capacity and higher transcript expression of stem cell genes Bmi1 and Sox2. Based on global transcriptome analysis of the in vitro treated hGBM, we also identify a hyper-aggressive form of glioma. Using our therapy-adapted hGBM-mouse xenograft model, we discover that despite tumour regression and increased mouse survival post-therapy, tumour relapse remains inevitable. The treatment-refractory cells again have increased self-renewal capacity and higher expression of Bmi1 and Sox2. Furthermore, by combining cellular DNA barcoding technology, which barcodes hGBM at single cell resolution, with our novel in vitro and in vivo therapy models, we are able to determine whether a pre-existing or a therapy driven subpopulation(s) seeds hGBM tumour relapse. Profiling the dynamic nature of heterogeneous hGBM subpopulations through disease progression and treatment may lead to the identification of novel therapeutic targets for the treatment of recurrent hGBM.