1,063 research outputs found
P wave crustal velocity structure in the greater Mount Rainier area from local earthquake tomography
We present results from a local earthquake tomographic imaging experiment in the greater Mount Rainier area. We inverted P wave arrival times from local earthquakes recorded at permanent and temporary Pacific Northwest Seismograph Network seismographs between 1980 and 1996. We used a method similar to that described by Lees and Crosson [1989], modified to incorporate the parameter separation method for decoupling the hypocenter and velocity problems. In the upper 7 km of the resulting model there is good correlation between velocity anomalies and surface geology. Many focal mechanisms within the St. Helens seismic zone have nodal planes parallel to the epicentral trend as well as to a north-south trending low-velocity trough, leading us to speculate that the trough represents a zone of structural weakness in which a moderate (M 6.5-7.0) earthquake could occur. In contrast, the western Rainier seismic zone does not correlate in any simple way with anomaly patterns or focal mechanism fault planes, leading us to infer that it is less likely to experience a moderate earthquake. A âŒ10 km-wide low-velocity anomaly occurs 5 to 18 km beneath the summit of Mount Rainier, which we interpret to be a signal of a region composed of hot, fractured rock with possible small amounts of melt or fluid. No systematic velocity pattern is observed in association with the southern Washington Cascades conductor. A midcrustal anomaly parallels the Olympic-Wallowa lineament as well as several other geophysical trends, indicating that it may play an important role in regional tectonics
Impact of the dosimetry approach on the resulting 90Y radioembolization planned absorbed doses based on 99mTc-MAA SPEC T-CT: is there agreement between dosimetry methods?
Background: Prior radioembolization, a simulation using 99mTc-macroaggregated
albumin as 90Y-microspheres surrogate is performed. Gamma scintigraphy images
(planar, SPECT, or SPECT-CT) are acquired to evaluate intrahepatic 90Y-microspheres
distribution and detect possible extrahepatic and lung shunting. These images may
be used for pre-treatment dosimetry evaluation to calculate the 90Y activity that
would get an optimal tumor response while sparing healthy tissues.
Several dosimetry methods are available, but there is still no consensus on the best
methodology to calculate absorbed doses. The goal of this study was to
retrospectively evaluate the impact of using different dosimetry approaches on the
resulting 90Y-radioembolization pre-treatment absorbed dose evaluation based on 99mTc-MAA images.
Methods: Absorbed doses within volumes of interest resulting from partition model
(PM) and 3D voxel dosimetry methods (3D-VDM) (dose-point kernel convolution and
local deposition method) were evaluated. Additionally, a new âMulti-tumor Partition
Modelâ (MTPM) was developed. The differences among dosimetry approaches were
evaluated in terms of mean absorbed dose and dose volume histograms within the
volumes of interest.
Results: Differences in mean absorbed dose among dosimetry methods are higher
in tumor volumes than in non-tumoral ones. The differences between MTPM and
both 3D-VDM were substantially lower than those observed between PM and any
3D-VDM. A poor correlation and concordance were found between PM and the
other studied dosimetry approaches.
DVH obtained from either 3D-VDM are pretty similar in both healthy liver and
individual tumors. Although no relevant global differences, in terms of absorbed
dose in Gy, between both 3D-VDM were found, important voxel-by-voxel differences
have been observed. Conclusions: Significant differences among the studied dosimetry approaches for 90Y-radioembolization treatments exist. Differences do not yield a substantial impact
in treatment planning for healthy tissue but they do for tumoral liver.
An individual segmentation and evaluation of the tumors is essential. In patients with
multiple tumors, the application of PM is not optimal and the 3D-VDM or the new
MTPM are suggested instead. If a 3D-VDM method is not available, MTPM is the best
option. Furthermore, both 3D-VDM approaches may be indistinctly used
3D Coronal Density Reconstruction and Retrieving the Magnetic Field Structure during Solar Minimum
Measurement of the coronal magnetic field is a crucial ingredient in
understanding the nature of solar coronal phenomena at all scales. We employed
STEREO/COR1 data obtained during a deep minimum of solar activity in February
2008 (Carrington rotation CR 2066) to retrieve and analyze the
three-dimensional (3D) coronal electron density in the range of heights from
1.5 to 4 Rsun using a tomography method. With this, we qualitatively deduced
structures of the coronal magnetic field. The 3D electron density analysis is
complemented by the 3D STEREO/EUVI emissivity in the 195 A band obtained by
tomography for the same CR. A global 3D MHD model of the solar corona was used
to relate the reconstructed 3D density and emissivity to open/closed magnetic
field structures. We show that the density maximum locations can serve as an
indicator of current sheet position, while the locations of the density
gradient maximum can be a reliable indicator of coronal hole boundaries. We
find that the magnetic field configuration during CR 2066 has a tendency to
become radially open at heliocentric distances greater than 2.5 Rsun. We also
find that the potential field model with a fixed source surface (PFSS) is
inconsistent with the boundaries between the regions with open and closed
magnetic field structures. This indicates that the assumption of the potential
nature of the coronal global magnetic field is not satisfied even during the
deep solar minimum. Results of our 3D density reconstruction will help to
constrain solar coronal field models and test the accuracy of the magnetic
field approximations for coronal modeling.Comment: Published in "Solar Physics
Hospital-based proton therapy implementation during the COVID pandemic: early clinical and research experience in a European academic institution
Introduction A rapid deploy of unexpected early impact of the COVID pandemic in Spain was described in 2020. Oncology practice was revised to facilitate decision-making regarding multimodal therapy for prevalent cancer types amenable
to multidisciplinary treatment in which the radiotherapy component searched more efcient options in the setting of the
COVID-19 pandemic, minimizing the risks to patients whilst aiming to guarantee cancer outcomes.
Methods A novel Proton Beam Therapy (PBT), Unit activity was analyzed in the period of March 2020 to March 2021.
Institutional urgent, strict and mandatory clinical care standards for early diagnosis and treatment of COVID-19 infection
were stablished in the hospital following national health-authoritiesâ recommendations. The temporary trends of patients
care and research projects proposals were registered.
Results 3 out of 14 members of the professional staf involved in the PBR intra-hospital process had a positive test for COVID
infection. Also, 4 out of 100 patients had positive tests before initiating PBT, and 7 out of 100 developed positive tests along
the weekly mandatory special checkup performed during PBT to all patients. An update of clinical performance at the PBT
Unit at CUN Madrid in the initial 500 patients treated with PBT in the period from March 2020 to November 2022 registers
a distribution of 131 (26%) pediatric patients, 63 (12%) head and neck cancer and central nervous system neoplasms and
123 (24%) re-irradiation indications. In November 2022, the activity reached a plateau in terms of patients under treatment
and the impact of COVID pandemic became sporadic and controlled by minor medical actions. At present, the clinical
data are consistent with an academic practice prospectively (NCT05151952). Research projects and scientifc production
was adapted to the pandemic evolution and its infuence upon professional time availability. Seven research projects based
in public funding were activated in this period and preliminary data on molecular imaging guided proton therapy in brain
tumors and post-irradiation patterns of blood biomarkers are reported.
Conclusions Hospital-based PBT in European academic institutions was impacted by COVID-19 pandemic, although clinical
and research activities were developed and sustained. In the post-pandemic era, the benefts of online learning will shape
the future of proton therapy education
Phospholipid oxidation and carotenoid supplementation in Alzheimerâs disease patients
Alzheimer's disease (AD) is a progressive, neurodegenerative disease, characterised by decline of memory, cognitive function and changes in behaviour. Generic markers of lipid peroxidation are increased in AD, therefore reactive oxygen species have been suggested to be involved in the aetiology of cognitive decline. Carotenoids are depleted in AD serum, therefore we have compared serum lipid oxidation between AD and age-matched control subjects before and after carotenoid supplementation. The novel oxidised phospholipid biomarker 1-palmitoyl-2-(5'-oxo-valeroyl)-sn-glycero-3-phosphocholine (POVPC) was analysed using electrospray ionization tandem mass spectrometry (MS) with multiple reaction monitoring (MRM), 8-isoprostane (IsoP) was measured by ELISA and ferric reducing antioxidant potential (FRAP) was measured by a colorimetric assay. AD patients (n=21) and healthy age-matched control subjects (n=16) were supplemented with either Macushieldâą (10 mg meso-zeaxanthin, 10 mg lutein, 2 mg zeaxanthin) or placebo (sunflower oil) for six months. The MRM-MS method determined serum POVPC sensitively (from 10 ”l serum) and reproducibly (CV=7.9%). At baseline, AD subjects had higher serum POVPC compared to age-matched controls, (p=0.017) and cognitive function was correlated inversely with POVPC (r=â0.37; p=0.04). After six months of carotenoid intervention, serum POVPC was not different in AD patients compared to healthy controls. However, POVPC was significantly higher in control subjects after six months of carotenoid intervention compared to their baseline (p=0.03). Serum IsoP concentration was unrelated to disease or supplementation. Serum FRAP was significantly lower in AD than healthy controls but was unchanged by carotenoid intervention (p=0.003). In conclusion, serum POVPC is higher in AD patients compared to control subjects, is not reduced by carotenoid supplementation and correlates with cognitive function
An Integrated TCGA Pan-Cancer Clinical Data Resource to Drive High-Quality Survival Outcome Analytics
For a decade, The Cancer Genome Atlas (TCGA) program collected clinicopathologic annotation data along with multi-platform molecular profiles of more than 11,000 human tumors across 33 different cancer types. TCGA clinical data contain key features representing the democratized nature of the data collection process. To ensure proper use of this large clinical dataset associated with genomic features, we developed a standardized dataset named the TCGA Pan-Cancer Clinical Data Resource (TCGA-CDR), which includes four major clinical outcome endpoints. In addition to detailing major challenges and statistical limitations encountered during the effort of integrating the acquired clinical data, we present a summary that includes endpoint usage recommendations for each cancer type. These TCGA-CDR findings appear to be consistent with cancer genomics studies independent of the TCGA effort and provide opportunities for investigating cancer biology using clinical correlates at an unprecedented scale. Analysis of clinicopathologic annotations for over 11,000 cancer patients in the TCGA program leads to the generation of TCGA Clinical Data Resource, which provides recommendations of clinical outcome endpoint usage for 33 cancer types
Measurement of the branching fraction
The branching fraction is measured in a data sample
corresponding to 0.41 of integrated luminosity collected with the LHCb
detector at the LHC. This channel is sensitive to the penguin contributions
affecting the sin2 measurement from The
time-integrated branching fraction is measured to be . This is the most precise measurement to
date
Measurement of the CP-violating phase \phi s in Bs->J/\psi\pi+\pi- decays
Measurement of the mixing-induced CP-violating phase phi_s in Bs decays is of
prime importance in probing new physics. Here 7421 +/- 105 signal events from
the dominantly CP-odd final state J/\psi pi+ pi- are selected in 1/fb of pp
collision data collected at sqrt{s} = 7 TeV with the LHCb detector. A
time-dependent fit to the data yields a value of
phi_s=-0.019^{+0.173+0.004}_{-0.174-0.003} rad, consistent with the Standard
Model expectation. No evidence of direct CP violation is found.Comment: 15 pages, 10 figures; minor revisions on May 23, 201
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