180 research outputs found
Luminosities and mass-loss rates of SMC and LMC AGB stars and Red Supergiants
(Abridged) Dust radiative transfer models are presented for 101 carbon stars
and 86 oxygen-rich evolved stars in the Magellanic Clouds for which 5-35 \mum\
{\it Spitzer} IRS spectra are available. The spectra are complemented with
available optical and infrared photometry to construct the spectral energy
distribution. A minimisation procedure is used to fit luminosity, mass-loss
rate and dust temperature at the inner radius. Different effective temperatures
and dust content are also considered. Periods from the literature and from new
OGLE-III data are compiled and derived. The O-rich stars are classified in
foreground objects, AGB stars and Red Super Giants.
For the O-rich stars silicates based on laboratory optical constants are
compared to "astronomical silicates". Overall, the grain type by Volk & Kwok
(1988) fit the data best. However, the fit based on laboratory optical
constants for the grains can be improved by abandoning the small-particle
limit. The influence of grain size, core-mantle grains and porosity are
explored.
Relations between mass-loss rates and luminosity and pulsation period are
presented and compared to the predictions of evolutionary models, those by
Vassiliadis & Wood (1993) and their adopted mass-loss recipe, and those based
on a Reimers mass-loss law with a scaling of a factor of five. The Vassiliadis
& Wood models describe the data better, although there are also some
deficiencies, in particular to the maximum adopted mass-loss rate.
The OGLE-III data reveal an O-rich star in the SMC with a period of 1749
days. Its absolute magnitude of makes it a good candidate
for a super-AGB star.Comment: A&A accepte
Different neuroinflammatory profile in amyotrophic lateral sclerosis and frontotemporal dementia is linked to the clinical phase
Objective To investigate the role of neuroinflammation in asymptomatic and symptomatic amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) mutation carriers. Methods The neuroinflammatory markers chitotriosidase 1 (CHIT1), YKL-40 and glial fibrillary acidic protein (GFAP) were measured in cerebrospinal fluid (CSF) and blood samples from asymptomatic and symptomatic ALS/FTD mutation carriers, sporadic cases and controls by ELISA. Results CSF levels of CHIT1, YKL-40 and GFAP were unaffected in asymptomatic mutation carriers (n=16). CHIT1 and YKL-40 were increased in gALS (p<0.001, n=65) whereas GFAP was not affected. Patients with ALS carrying a CHIT1 polymorphism had lower CHIT1 concentrations in CSF (-80%) whereas this polymorphism had no influence on disease severity. In gFTD (n=23), increased YKL-40 and GFAP were observed (p<0.05), whereas CHIT1 was nearly not affected. The same profile as in gALS and gFTD was observed in sALS (n=64/70) and sFTD (n=20/26). CSF and blood concentrations correlated moderately (CHIT1, r=0.51) to weak (YKL-40, r=0.30, GFAP, r=0.39). Blood concentrations of these three markers were not significantly altered in any of the groups except CHIT1 in gALS of the Ulm cohort (p<0.05). Conclusion Our data indicate that neuroinflammation is linked to the symptomatic phase of ALS/FTD and shows a similar pattern in sporadic and genetic cases. ALS and FTD are characterised by a different neuroinflammatory profile, which might be one driver of the diverse presentations of the ALS/FTD syndrome
Neurofilament as a blood marker for diagnosis and monitoring of primary progressive aphasias
Objective: To assess the utility of serum neurofilament for diagnosis and monitoring of primary progressive aphasia (PPA) variants. Methods: We investigated neurofilament light chain (NF-L) levels in blood of 99 patients with PPA (40 with nonfluent variant PPA [nfvPPA], 38 with semantic variant PPA [svPPA], 21 with logopenic variant PPA [lvPPA]) and compared diagnostic performance with that reached by CSF NF-L, phosphorylated neurofilament heavy chain (pNF-H), b-amyloid (Ab(1)-42), tau, and phosphorylated tau. The longitudinal change of blood NF-L levels was measured and analyzed for correlation with functional decline and brain atrophy. Results: Serum NF-L is increased in PPA compared to controls and discriminates between nfvPPA/svPPA and lvPPA with 81% sensitivity and 67% specificity (cutoff 31 pg/mL). CSF NF-L, pNF-H, tau, phosphorylated tau, and Ab1-42 achieved similar performance, and pNF-H was the only marker for discrimination of nfvPPA from svPPA/lvPPA. In most patients with nfvPPA and svPPA, but not lvPPA, serum NF-L increased within follow-up. The increase correlated with functional decline and progression of atrophy of the left frontal lobe of all patients with PPAs and the right middle frontal gyrus of patients with nfvPPA and svPPA. Conclusions: Blood level of NF-L can aid the differential diagnosis of PPA variants, especially in combination with CSF pNF-H. Because serum NF-L correlates with functional decline and atrophy in the disease course, it qualifies as an objective disease status marker. Extended follow-up studies with cases of known neuropathology are imperative
Different CSF protein profiles in amyotrophic lateral sclerosis and frontotemporal dementia with C9orf72 hexanucleotide repeat expansion
Objectives: The hexanucleotide repeat expansion in the C9orf72 gene is the most common mutation associated with amyotrophic lateral sclerosis (C9-ALS) and frontotemporal dementia (C9-FTD). Until now, it is unknown which factors define whether C9orf72 mutation carriers develop ALS or FTD. Our aim was to identify protein biomarker candidates in the cerebrospinal fluid (CSF) which differentiate between C9-ALS and C9-FTD and might be indicative for the outcome of the mutation. Methods We compared the CSF proteome of 16 C9-ALS and 8 C9-FTD patients and 11 asymptomatic C9orf72 mutation carriers (CAR) by isobaric tags for relative and absolute quantitation. Eleven biomarker candidates were selected from the pool of differentially regulated proteins for further validation by multiple reaction monitoring and single-molecule array in a larger cohort (n=156). Results In total, 2095 CSF proteins were identified and 236 proteins were significantly different in C9-ALS versus C9-FTD including neurofilament medium polypeptide (NEFM) and chitotriosidase-1 (CHIT1). Eight candidates were successfully validated including significantly increased ubiquitin carboxyl-terminal hydrolase isozyme L1 (UCHL1) levels in C9-ALS compared with C9-FTD and controls and decreased neuronal pentraxin receptor (NPTXR) levels in C9-FTD versus CAR. Conclusions: This study presents a deep proteomic CSF analysis of C9-ALS versus C9-FTD patients. As a proof of concept, we observed higher NEFM and CHIT1 CSF levels in C9-ALS. In addition, we also show clear upregulation of UCHL1 in C9-ALS and downregulation of NPTXR in C9-FTD. Significant differences in UCHL1 CSF levels may explain diverging ubiquitination and autophagy processes and NPTXR levels might reflect different synapses organisation processes
Serum neurofilament light chain in behavioral variant frontotemporal dementia
Objective To determine the association of serum neurofilament light chain (NfL) with functional deterioration and brain atrophy during follow-up of patients with behavioral variant frontotemporal dementia (bvFTD). Methods Blood NfL levels from 74 patients with bvFTD, 26 with Alzheimer disease (AD), 17 with mild cognitive impairment (MCI), and 15 healthy controls (Con) at baseline and follow-up were determined and analyzed for the diagnostic potential in relation to functional assessment (Clinical Dementia Rating Scale Sum of Boxes [CDR-SOB], frontotemporal lobar degeneration-related CDR-SOB, Mini-Mental State Examination [MMSE]) and brain volumetry. Results At baseline, serum NfL level correlated with CSFNfL (bvFTD r = 0.706, p < 0.0001;AD/MCI r = 0.666, p = 0.0003). Highest serum levels were observed in bvFTD (p < 0 0.0001 vs Con and MCI, p = 0.0078 vs AD, respectively). Discrimination of bvFTD from Con/MCI/AD was possible with 91%/74%/74% sensitivity and 79%/74%/58% specificity. At follow-up, serum NfL increased in bvFTD and AD (p = 0.0039 and p = 0.0006, respectively). At baseline and follow-up, NfL correlated with functional scores of patients with bvFTD (e.g., CDR-SOB [baseline] r = 0.4157, p = 0.0006;[follow-up] r = 0.5629, p < 0.0001) and with atrophy in the gray and white matter of many brain regions including frontal and subcortical areas (e.g., frontal lobe: r = -0.5857, p < 0.0001;95% confidence interval -0.7415 to -0.3701). For patients with AD/MCI, NfL correlated with the functional performance as well (e.g., CDR-SOB [baseline] r = 0.6624, p < 0.0001;[follow-up] r = 0.5659, p = 0.0003) but not with regional brain volumes. Conclusions As serum NfL correlates with functional impairment and brain atrophy in bvFTD at different disease stages, we propose it as marker of disease severity, paving the way for its future use as outcome measure for clinical trials. Classification of evidence This study provides Class III evidence that for patients with cognitive problems, serum NfL concentration discriminates bvFTD from other forms of dementia
The structure of Planetary Nebulae: theory vs. practice
This paper - the first of a short series dedicated to the long-stan ding
astronomical problem of de-projecting the bi-dimensional apparent morpholog y
of a three-dimensional mass of gas - focuses on the density distribution in
real Planetary Nebulae (and all types of expanding nebulae). We introduce some
basic theoretical notions, discuss the observational methodology and develope
the accurate procedure for the determination of the matter radial profile
within the sharp portion of nebula in the plane of the sky identified by the
zero-velocity-pixel-column (zvpc) of high-resolution spectral images. Moreover,
a series of evolutive snapshots is presented, combining illustrative examples
of model- and true-Planetary Nebulae. Last, the general and specific
applications of the method (and some caveats) are discussed.Comment: 18 pages, 7 figures, A&A accepte
The Near Infrared Imager and Slitless Spectrograph for the James Webb Space Telescope -- IV. Aperture Masking Interferometry
The James Webb Space Telescope's Near Infrared Imager and Slitless
Spectrograph (JWST-NIRISS) flies a 7-hole non-redundant mask (NRM), the first
such interferometer in space, operating at 3-5 \micron~wavelengths, and a
bright limit of magnitudes in W2. We describe the NIRISS Aperture
Masking Interferometry (AMI) mode to help potential observers understand its
underlying principles, present some sample science cases, explain its
operational observing strategies, indicate how AMI proposals can be developed
with data simulations, and how AMI data can be analyzed. We also present key
results from commissioning AMI. Since the allied Kernel Phase Imaging (KPI)
technique benefits from AMI operational strategies, we also cover NIRISS KPI
methods and analysis techniques, including a new user-friendly KPI pipeline.
The NIRISS KPI bright limit is W2 magnitudes. AMI (and KPI) achieve
an inner working angle of mas that is well inside the mas
NIRCam inner working angle for its circular occulter coronagraphs at comparable
wavelengths.Comment: 30 pages, 10 figure
Reply: Adult-onset distal spinal muscular atrophy: a new phenotype associated with KIF5A mutations
The development of a web- and a print-based decision aid for prostate cancer screening
Background Whether early detection and treatment of prostate cancer (PCa) will reduce disease-related mortality remains uncertain. As a result, tools are needed to facilitate informed decision making. While there have been several decision aids (DAs) developed and tested, very few have included an exercise to help men clarify their values and preferences about PCa screening. Further, only one DA has utilized an interactive web-based format, which allows for an expansion and customization of the material. We describe the development of two DAs, a booklet and an interactive website, each with a values clarification component and designed for use in diverse settings.
Methods We conducted two feasibility studies to assess men\u27s (45-70 years) Internet access and their willingness to use a web- vs. a print-based tool. The booklet was adapted from two previous versions evaluated in randomized controlled trials (RCTs) and the website was created to closely match the content of the revised booklet. Usability testing was conducted to obtain feedback regarding draft versions of the materials. The tools were also reviewed by a plain language expert and the interdisciplinary research team. Feedback on the content and presentation led to iterative modifications of the tools.
Results The feasibility studies confirmed that the Internet was a viable medium, as the majority of men used a computer, had access to the Internet, and Internet use increased over time. Feedback from the usability testing on the length, presentation, and content of the materials was incorporated into the final versions of the booklet and website. Both the feasibility studies and the usability testing highlighted the need to address men\u27s informed decision making regarding screening.
Conclusions Informed decision making for PCa screening is crucial at present and may be important for some time, particularly if a definitive recommendation either for or against screening does not emerge from ongoing prostate cancer screening trials. We have detailed our efforts at developing print- and web-based DAs to assist men in determining how to best meet their PCa screening preferences. Following completion of our ongoing RCT designed to test these materials, our goal will be to develop a dissemination project for the more effective tool
Prognostic limitations of the Eurotransplant-donor risk index in liver transplantation
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