2,760 research outputs found
Employing a Modified Diffuser Momentum Model to Simulate Ventilation of the Orion CEV
The Ansys CFX CFD modeling tool was used to support the design efforts of the ventilation system for the Orion CEV. CFD modeling was used to establish the flow field within the cabin for several supply configurations. A mesh and turbulence model sensitivity study was performed before the design studies. Results were post-processed for comparison with performance requirements. Most configurations employed straight vaned diffusers to direct and throw the flow. To manage the size of the models, the diffuser vanes were not resolved. Instead, a momentum model was employed to account for the effect of the diffusers. The momentum model was tested against a separate, vane-resolved side study. Results are presented for a single diffuser configuration for a low supply flow case
Deep learning-based segmentation of malignant pleural mesothelioma tumor on computed tomography scans: application to scans demonstrating pleural effusion
Tumor volume is a topic of interest for the prognostic assessment, treatment response evaluation, and staging of malignant pleural mesothelioma. Many mesothelioma patients present with, or develop, pleural fluid, which may complicate the segmentation of this disease. Deep convolutional neural networks (CNNs) of the two-dimensional U-Net architecture were trained for segmentation of tumor in the left and right hemithoraces, with the networks initialized through layers pretrained on ImageNet. Networks were trained on a dataset of 5230 axial sections from 154 CT scans of 126 mesothelioma patients. A test set of 94 CT sections from 34 patients, who all presented with both tumor and pleural effusion, in addition to a more general test set of 130 CT sections from 43 patients, were used to evaluate segmentation performance of the deep CNNs. The Dice similarity coefficient (DSC), average Hausdorff distance, and bias in predicted tumor area were calculated through comparisons with radiologist-provided tumor segmentations on the test sets. The present method achieved a median DSC of 0.690 on the tumor and effusion test set and achieved significantly higher performance on both test sets when compared with a previous deep learning-based segmentation method for mesothelioma
Comparison of High-degree Solar Acoustic Frequencies and Asymmetry between Velocity and Intensity Data
Using the local helioseismic technique of ring diagram we analyze the
frequencies of high--degree f- and p-modes derived from both velocity and
continuum intensity data observed by MDI. Fitting the spectra with asymmetric
peak profiles, we find that the asymmetry associated with velocity line
profiles is negative for all frequency ranges agreeing with previous
observations while the asymmetry of the intensity profiles shows a complex and
frequency dependent behavior. We also observe systematic frequency differences
between intensity and velocity spectra at the high end of the frequency range,
mostly above 4 mHz. We infer that this difference arises from the fitting of
the intensity rather than the velocity spectra. We also show that the frequency
differences between intensity and velocity do not vary significantly from the
disk center to the limb when the spectra are fitted with the asymmetric profile
and conclude that only a part of the background is correlated with the
intensity oscillations.Comment: Accepted for publication in Astrophysical Journa
Thermodynamics of Heat Shock Response
Production of heat shock proteins are induced when a living cell is exposed
to a rise in temperature. The heat shock response of protein DnaK synthesis in
E.coli for temperature shifts from temperature T to T plus 7 degrees,
respectively to T minus 7 degrees is measured as function of the initial
temperature T. We observe a reversed heat shock at low T. The magnitude of the
shock increases when one increase the distance to the temperature , thereby mimicking the non monotous stability of proteins at low
temperature. Further we found that the variation of the heat shock with T
quantitatively follows the thermodynamic stability of proteins with
temperature. This suggest that stability related to hot as well as cold
unfolding of proteins is directly implemented in the biological control of
protein folding. We demonstrate that such an implementation is possible in a
minimalistic chemical network.Comment: To be published in Physical Review Letter
Characterization Measurements of Sapphire and Diamond based KIDs for Polarimetric Plasma Diagnostics
On the Formation Height of the SDO/HMI Fe 6173 Doppler Signal
The Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics
Observatory (SDO) is designed to study oscillations and the mag- netic field in
the solar photosphere. It observes the full solar disk in the Fe I absorption
line at 6173\AA . We use the output of a high-resolution 3D, time- dependent,
radiation-hydrodynamic simulation based on the CO5BOLD code to calculate
profiles F({\lambda},x,y,t) for the Fe I 6173{\AA} line. The emerging profiles
F({\lambda},x,y,t) are multiplied by a representative set of HMI filter
transmission profiles R_i({\lambda},1 \leq i \leq 6) and filtergrams
I_i(x,y,t;1 \leq i \leq 6) are constructed for six wavelengths. Doppler
velocities V_HMI(x,y,t) are determined from these filtergrams using a
simplified version of the HMI pipeline. The Doppler velocities are correlated
with the original velocities in the simulated atmosphere. The cross-
correlation peaks near 100 km, suggesting that the HMI Doppler velocity signal
is formed rather low in the solar atmosphere. The same analysis is performed
for the SOHO/MDI Ni I line at 6768\AA . The MDI Doppler signal is formed
slightly higher at around 125 km. Taking into account the limited spatial
resolution of the instruments, the apparent formation height of both the HMI
and MDI Doppler signal increases by 40 to 50 km. We also study how
uncertainties in the HMI filter-transmission profiles affect the calculated
velocities.Comment: 15 pages, 11 Figure
Proper orthogonal decomposition of solar photospheric motions
The spatio-temporal dynamics of the solar photosphere is studied by
performing a Proper Orthogonal Decomposition (POD) of line of sight velocity
fields computed from high resolution data coming from the MDI/SOHO instrument.
Using this technique, we are able to identify and characterize the different
dynamical regimes acting in the system. Low frequency oscillations, with
frequencies in the range 20-130 microHz, dominate the most energetic POD modes
(excluding solar rotation), and are characterized by spatial patterns with
typical scales of about 3 Mm. Patterns with larger typical scales of 10 Mm, are
associated to p-modes oscillations at frequencies of about 3000 microHz.Comment: 8 figures in jpg in press on PR
Women, anger, and aggression an interpretative phenomenological analysis
This study reports a qualitative phenomenological investigation of anger and anger-related aggression in the context of the lives of individual women. Semistructured interviews with five women are analyzed using interpretative phenomenological analysis. This inductive approach aims to capture the richness and complexity of the lived experience of emotional life. In particular, it draws attention to the context-dependent and relational dimension of angry feelings and aggressive behavior. Three analytic themes are presented here: the subjective experience of anger, which includes the perceptual confusion and bodily change felt by the women when angry, crying, and the presence of multiple emotions; the forms and contexts of aggression, paying particular attention to the range of aggressive strategies used; and anger as moral judgment, in particular perceptions of injustice and unfairness. The authors conclude by examining the analytic observations in light of phenomenological thinking
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