1,371 research outputs found
Bridging the ensemble Kalman and particle filter
In many applications of Monte Carlo nonlinear filtering, the propagation step
is computationally expensive, and hence, the sample size is limited. With small
sample sizes, the update step becomes crucial. Particle filtering suffers from
the well-known problem of sample degeneracy. Ensemble Kalman filtering avoids
this, at the expense of treating non-Gaussian features of the forecast
distribution incorrectly. Here we introduce a procedure which makes a
continuous transition indexed by gamma in [0,1] between the ensemble and the
particle filter update. We propose automatic choices of the parameter gamma
such that the update stays as close as possible to the particle filter update
subject to avoiding degeneracy. In various examples, we show that this
procedure leads to updates which are able to handle non-Gaussian features of
the prediction sample even in high-dimensional situations
TNFR1 signalling is critical for the development of demyelination and the limitation of T-cell responses during immune-mediated CNS disease
In this review we summarize the essential findings about the function of tumour necrosis factor (TNF) and its cognate receptors TNFR1 and TNFR2, and lymphotoxin α (LT-α) ligands in immune-mediated CNS inflammation and demyelination. The advent of homologous recombination technology in rodents provides a new method which has been used during the last 5 years and has led to insights into the pathophysiology of experimental autoimmune encephalomyelitis (EAE) in an unprecedented way. Studies with knockout mice in which genes of the TNF ligand/receptor superfamily are not expressed and studies with transgenic mice overexpressing TNF and TNFR reveal the critical role of the TNFR1 signalling pathway in the control of CNS demyelination and inflammation. These studies provide novel findings and at the same time shed light on the complex pathophysiology of EAE. Together, these findings may contribute to better understanding of EAE and open new avenues in experimental therapies for multiple sclerosi
Protective Effect of a 21-Aminosteroid during Experimental Pneumococcal Meningitis
This study investigated whether the 21-aminosteroid U74389F, an inhibitor of lipid peroxidation, attenuates pathophysiologic changes in experimental pneumococcal meningitis. Infected rats injected intravenously with vehicle and U74389F developed increases in regional cerebral blood flow (rCBF), intracranial pressure (ICP), brain water content, and white blood cells (WBC) in cerebrospinal fluid (CSF) within 8 h after intracisternal challenge. Pretreatment with or administration of U74389F 4 h after infection significantly reduced the increase in ICP but had no effect on rCBF increase. Moreover, U74389F pretreatment significantly reduced brain water content and CSF WBC count. In vitro, U74389F inhibited iron-dependent lipid peroxidation of astrocyte cultures and the production of tumor necrosis factor-a, interleukin-6, and nitric oxide by stimulated macrophages. These data suggest that U74389F modulates early pathophysiologic alterations in experimental pneumococcal meningiti
The Maglemosian skeleton from Koelbjerg, Denmark revisited: identifying sex and provenance
The Koelbjerg individual, dated c. 8500 cal BC, represents the earliest human skeletal remains described from Scandinavia. Based on ancient DNA, strontium isotope and statistical anthropological analyses the individual’s sex, haplogroup and geographical provenance are here analysed and discussed. In contrast to previous claims, our genetic and anthropological analyses show that this individual was a male. Additionally, the strontium isotope ratio of one of his first molars indicates that he most likely grew up locally
Thymosin beta 4 gene silencing decreases stemness and invasiveness in glioblastoma
Glioblastomas are incurable malignant primary brain tumours. Wirsching etal. investigate the effects of altered expression of thymosin beta 4 (TB4), a polypeptide implicated in neural development and wound healing, in glioma models. TB4 silencing inhibited migration and invasion of glioma cells invitro, and enhanced survival of glioma-bearing mic
Sanierung Stauanlagen im ZĂĽrcher Oberland
Aufsatz veröffentlicht in: "Wasserbau-Symposium 2021: Wasserbau in Zeiten von Energiewende, Gewässerschutz und Klimawandel, Zurich, Switzerland, September 15-17, 2021, Band 1" veröffentlicht unter: https://doi.org/10.3929/ethz-b-00049975
Detection Efficacy of 68Ga-PSMA-11 PET/CT in Biochemical Recurrence of Prostate Cancer with Very Low PSA Levels : A 7-Year, Two-Center “Real-World” Experience
In biochemical recurrence of prostate cancer (BCR), prompt tumor localization guides early
treatment, potentially improving patient outcomes. Gallium-68 prostate-specific membrane antigen11 positron emission tomography/computed tomography (68Ga-PSMA-11 PET/CT) detection rates of
lesions suspicious for prostate cancer are well known to rise along with prostate-specific antigen (PSA)
concentration. However, published data are limited regarding very low values (≤0.2 ng/mL). We
retrospectively analyzed ~7-year “real-world” experience in this setting in a large post-prostatectomy
cohort (N = 115) from two academic clinics. Altogether 44 lesions were detected in 29/115 men
(25.2%) (median [minimum–maximum] 1 [1–4]/positive scan). The apparent oligometastatic disease
was found in nine patients (7.8%) at PSA as low as 0.03 ng/mL. Scan positivity rates were highest
when PSA was >0.15 ng/mL, PSA doubling time was ≤12 months, or the Gleason score was ≥7b
(in 83 and 107 patients, respectively, with available data); these findings were statistically significant
(p ≤ 0.04), except regarding PSA level (p = 0.07). Given the benefits of promptly localizing recurrence,
our observations suggest the potential value of 68Ga-PSMA-11 PET/CT in the very low PSA BCR
setting, especially in cases with more rapid PSA doubling time or with high-risk histology
An Observational Estimate for the Mean Secular Evolution Rate in Spiral Galaxies
We have observationally quantified the effect of gravitational torques on
stars in disk galaxies due to the stellar distribution itself and explored
whether these torques are efficient at transporting angular momentum within a
Hubble Time. We derive instantaneous torque maps for a sample of 24 spiral
galaxies, based on stellar mass maps that were derived using the pixel-by-pixel
mass-to-light estimator by Zibetti, Rix and Charlot. In conjunction with an
estimate of the rotation velocity, the mass maps allow us to determine the
torque-induced instantaneous angular momentum flow across different radii,
resulting from the overall stellar distributions for each galaxy in the sample.
By stacking the sample, which effectively replaces a time average by an
ensemble average, we find that the torques due to the stellar disk act to
transport angular momentum outward over much of the disk (within 3 disk scale
lengths). The strength of the ensemble-averaged gravitational torques within
one disk scale length have a timescale of ~ 4 Gyr for angular momentum
redistribution. This study is the first to observationally determine the
strength of torque-driven angular momentum flow of stars for a sample of spiral
galaxies, providing an important empirical constraint on secular evolution.
(abridged)Comment: 24 pages, 18 Figures A high resolution version of this paper can be
found at http://www.mpia-hd.mpg.de/~foyle/papers/MN-09-1350-MJ.pd
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