New boron abundances or upper limits have been determined for 8 early-B stars in the young Galactic open cluster NGC 3293, using ultraviolet spectra obtained by the Hubble Space Telescope Cosmic ...Origins Spectrograph. With previous observations, there are now 18 early-B stars in this cluster with boron measurements. Six of the newly observed stars have projected rotational velocities greater than 200 km/s, allowing new constraints on rotationally driven mixing in main-sequence stars. When comparing to synthetic model populations, we find that the majority of our sample stars agree well with the predicted trends of stronger boron depletion for larger rotation and for larger mass or luminosity. Based on those, a smaller than the canonical rotational mixing efficiency,(fc = 0.0165 vs the more standard value of 0.033), appears to be required. However, our five most slowly rotating stars are not well explained by rotational mixing, and we speculate that they originate from binary mergers.
In this prospective evaluation of serum and CSF samples, all but two CSF GFAPα-IgG positive patients had autoimmune meningoencephalomyelitis while serum GFAPα-IgG positivity alone was less specific. ...Phenotypes were diverse among patients that were serum positive only. Adult and pediatric clinical presentations were similar. Most patients were immunotherapy responsive. Co-existing NMDA-R-IgG and cancer were associated with lack of response to first-line immunotherapy. Among patients with follow-up information, 18% had relapses. This study demonstrates CSF GFAPα-IgG is a specific autoimmune meningoencephalomyelitis biomarker, with favorable corticosteroid response. Lack of response should prompt evaluation for co-existing NMDA-R-IgG or malignancy.
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•Autoimmune GFAP astrocytopathy is a steroid-responsive meningoencephalomyelitis or limited form thereof.•CSF GFAPα-IgG is more specific than serum for this phenotype.•Autoimmune GFAP astrocytopathy can affect children; clinical presentations and outcomes are similar to adults.•Early immunotherapy refractoriness should prompt consideration of co-existing NMDA-R-IgG or neoplasia.•A minority of cases (18%) have a relapsing clinical course.
Objective
To describe an expanded phenotypic spectrum and longitudinal outcome in 256 LGI1‐IgG–seropositive and/or CASPR2‐IgG–seropositive patients.
Methods
Patients were identified through service ...neural autoantibody evaluation. Ninety‐five had longitudinal follow‐up (7–456 months; median = 35).
Results
Among 3,910 patients tested, 196 were LGI1‐IgG positive, 51 were CASPR2‐IgG positive, and 9 were dual positive. Cerebrospinal fluid testing was less sensitive than serum testing, detecting only 24 of 38 (63%) LGI1‐IgG–positive and 5 of 6 (83%) CASPR2‐IgG–positive patients. LGI1‐IgG–positive specimens had higher voltage‐gated potassium channel–IgG immunoprecipitation values (0.33nmol/l, range = 0.02–5.14) than CASPR2‐IgG–positive specimens (0.10nmol/l, range = 0.00–0.45, p < 0.001). Of patients presenting with pain or peripheral nervous system (PNS) manifestations, 39% were LGI1‐IgG seropositive (7% had solely neuropathy or pain). Multivariate analysis identified age as the only significant predictor of central nervous system (CNS) versus PNS involvement (>50 years; odds ratio = 15, p < 0.001). Paroxysmal dizziness spells (PDS), a unique LGI1‐IgG accompaniment (14% of patients), frequently delayed the diagnosis. T2‐mesiotemporal hyperintensity was more common in LGI1‐IgG–positive (41%) than in CASPR2‐IgG–positive patients (p = 0.033). T1‐bright basal ganglia were confined to LGI1‐IgG–positive patients with faciobrachial–dystonic seizures (9 of 39, 31%). Cancer was found in 44% of LGI1‐IgG/CASPR2‐IgG dual seropositive patients (one‐third thymoma). Response to initial immunotherapy was favorable in 97%; mean modified Rankin score was 3 (range = 1–5) at onset and 1.74 (range = 0–6) at last follow‐up, with 9% having severe refractory disability, 20% being asymptomatic, 28% receiving immunotherapy, and 58% receiving antiepileptic medication.
Interpretation
Older age is a strong predictor of CNS involvement in patients seropositive for CASPR2‐IgG or LGI1‐IgG. Pain, peripheral manifestations, and stereotypic paroxysmal dizziness spells are common with LGI1‐IgG. Response to initial immunotherapy is often favorable, but some patients remain severely disabled, requiring long‐term immunotherapy and/or antiepileptic medications. Ann Neurol 2017;82:79–92
An ultraviolet and optical spectral atlas of 15 O stars in the Small Magellanic Cloud (SMC) is presented and described. The echelle data have resolving powers of order 104; they were obtained with ...theHubble Space TelescopeSpace Telescope Imaging Spectrograph in the UV, and at the Anglo‐Australian Telescope or the European Southern Observatory 3.6 m in the optical. The ultimate objective is to develop metal‐deficient templates for the interpretation of distant starbursts, but here we discuss interesting new properties of the SMC stars themselves, revealed by the high quality of these data. The SMC metal deficiency produces anomalously weak stellar‐wind profiles along the entire O main sequence, as well as at intermediate luminosities; the first intermediate Siivλ1400 wind profile in the SMC is shown. The second known Of star in the SMC displays wind peculiarities that are identical to those of its spectral classmate, again likely due to the low systemic metallicity. Several objects display marked CNO anomalies, including the first cases of Ciiiλ4650 emission without Niiiλ4640 in O‐type spectra. The N/C ratio appears to increase with mass, extent of evolution away from the zero‐age main sequence, and/or rotational velocity in the young cluster NGC 346. In addition, the first examples of Onfp (Oef) and Of?p spectra in the SMC have been found (the latter being only the fourth member of its peculiar shell category known anywhere). The UV wind characteristics of these objects correlate with their optical peculiarities. All these spectroscopic phenomena provide diagnostics of the evolutionary status of metal‐deficient massive stars.
The Small Magellanic Cloud (SMC) shows a large variation in ultraviolet (UV) dust extinction curves, ranging from Milky Way-like (MW) to significantly steeper curves with no detectable 2175 A bump. ...This result is based on a sample of only nine sightlines. From HST/STIS and IUE spectra of OB stars, we have measured UV extinction curves along 32 SMC sightlines where eight of these curves were published previously. We find 16 sightlines with steep extinction with no detectable 2175 A bump, four sightlines with MW-like extinction with a detectable 2175 A bump, two sightlines with fairly flat UV extinction and weak/absent 2175 A bumps, and 10 sightlines with unreliable curves due to low SMC dust columns. Our expanded sample shows that the sightlines with and without the 2175 A bump are located throughout the SMC and not limited to specific regions. The average extinction curve of the 16 bumpless sightlines is very similar to the previous average based on four sightlines. We find no correlation between dust column and the strength of the 2175 A bump. We test the hypothesis that the 2175 A bump is due to the same dust grains that are responsible for the mid-infrared carbonaceous (PAH) emission features and find they are correlated, confirming recent work in the MW. Overall, the slope of the UV extinction increases as the amplitudes of the 2175 A bump and far-UV curvature decrease. Finally, the UV slope is correlated with \(N(HI)/A(V)\) and the 2175 A bump and nonlinear far-UV rise amplitudes are anti-correlated with \(N(HI)/A(V)\).
1. Predictions of the identities and ecological impacts of invasive alien species are critical for risk assessment, but presently we lack universal and standardized metrics that reliably predict the ...likelihood and degree of impact of such invaders (i.e. measurable changes in populations of affected species). This need is especially pressing for emerging and potential future invaders that have no invasion history. Such a metric would also ideally apply across diverse taxonomic and trophic groups. 2. We derive a new metric of invader ecological impact that blends: (i) the classic Functional Response (FR; consumer per capita effect) and Numerical Response (NR; consumer population response) approaches to determining consumer impact, that is, the Total Response (TR = FR × NR), with; (ii) the Tarker-Lonsdale equation' for invader impact, where Impact = Range × Abundance × Effect (per capita effect), into; (iii) a new metric, Relative Impact Potential (RIP), where RIP = FR × Abundance. The RIP metric is an invader/native ratio, where values > 1 predict that invader ecological impact will occur, and increasing values above 1 indicate increasing impact. In addition, the invader/invader RIP ratio allows comparisons of the ecological impacts of different invaders. 3. Across a diverse range of trophic and taxonomic groups, including predators, herbivores, animals and plants (22 invader/native systems with 47 individual comparisons), high-impact invaders were significantly associated with higher FRs compared to native trophic analogues. However, the RIP metric substantially improves this association, with 100% predictive power of high-impact invaders. 4. Further, RIP scores were significantly and positively correlated with two independent ecological impact scores for invaders, allowing prediction of the degree of impact of invasive alien species with the RIP metric. Finally, invader/invader RIP scores were also successful in identifying and associating with higher impacting invasive alien species. 5. Synthesis and applications. The Relative Impact Potential metric combines the per capita effects of invaders with their abundances, relative to trophically analogous natives, and is successful in predicting the likelihood and degree of ecological impact caused by invasive alien species. As the metric constitutes readily measurable features of individuals, populations and species across abiotic and biotic context-dependencies, even emerging and potential future invasive alien species can be assessed. The Relative Impact Potential metric can be rapidly utilized by scientists and practitioners and could inform policy and management of invasive alien species across diverse taxonomic and trophic groups.
Blue supergiants are the brightest stars in their host galaxies and yet their evolutionary status has been a long-standing problem in stellar astrophysics. In this pioneering work, we present a large ...sample of 59 early B-type supergiants in the Large Magellanic Cloud with newly derived stellar parameters and identify the signatures of stars born from binary mergers among them. We simulate novel 1D merger models of binaries consisting of supergiants with hydrogen-free cores (primaries) and main-sequence companions (secondaries) and consider the effects of interaction of the secondary with the core of the primary. We follow the evolution of the new-born \(16-40\) M\(_{\odot}\) stars until core-carbon depletion, close to their final pre-explosion structure. Unlike stars which are born alone, stars born from such stellar mergers are blue throughout their core helium-burning phase and reproduce the surface gravities and Hertzsprung-Russel diagram positions of most of our sample. This indicates that the observed blue supergiants are structurally similar to merger-born stars. Moreover, the large nitrogen-to-carbon and oxygen ratios, and helium enhancements exhibited by at least half our data sample are uniquely consistent with our model predictions, leading us to conclude that a large fraction of blue supergiants are indeed products of binary mergers.
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