scholarly journals FASTWIND reloaded: Complete comoving frame transfer for “all” contributing lines

2016 ◽  
Vol 12 (S329) ◽  
pp. 435-435
Author(s):  
Joachim Puls
Keyword(s):  
Atmospheric Model ◽  
Desktop Computer ◽  
Formal Integral ◽  
Spectrum Synthesis ◽  
Line Transfer ◽  
Alternative Code ◽  
The Individual ◽  
Ir Spectroscopic ◽  
Radiative Acceleration ◽  
Individual Line

AbstractFASTWIND is a unified NLTE atmosphere/spectrum synthesis code originally designed (and frequently used) for the optical/IR spectroscopic analysis of massive stars with winds. Until the previous version (v10), the line transfer for background elements (mostly from the iron-group) was performed in an approximate way, by calculating the individual line-transitions in a single-line Sobolev or comoving frame approach, and by adding up the individual opacities and source functions to quasi-continuum quantities that are used to determine the radiation field for the complete spectrum (see Puls et al. 2005, A&A 435, 669, and updates).We have now updated this approach (v11) and calculate, for all contributing lines (from elements H to Zn), the radiative transfer in the comoving frame, thus also accounting for line-overlap effects in an “exact” way. Related quantities such as temperature, radiative acceleration and formal integral have been improved in parallel. For a typical massive star atmospheric model, the computation times (from scratch, and for a modern desktop computer) are 1.5 h for the atmosphere/NLTE part, and 30 to 45 minutes (when not parallelized) for the formal integral (i.e., SED and normalized flux) in the ranges 900 to 2000 and 3800 to 7000 Å(Δλ = 0.03 Å).We compare our new with analogous results from the alternative code CMFGEN (Hillier & Miller 1998, ApJ 496, 407, and updates), for a grid consisting of 5 O-dwarf and 5 O-supergiant models of different spectral subtype. In most cases, the agreement is very good or even excellent (i.e., for the radiative acceleration), though also certain differences can be spotted. A comparison with results from the previous, approximate method shows equally good agreement, though also here some differences become obvious. Besides the possibility to calculate the (total) radiative acceleration, the new FASTWIND version will allow us to investigate the UV-part of the spectrum in parallel with the optical/IR domain.

scholarly journals Supervised dimensionality reduction for big data

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Joshua T. Vogelstein ◽  
Eric W. Bridgeford ◽  
Minh Tang ◽  
Da Zheng ◽  
Christopher Douville ◽  
...  
Keyword(s):  
Dimensionality Reduction ◽  
Data Science ◽  
Real Data ◽  
Low Rank ◽  
Conditional Moment ◽  
Desktop Computer ◽  
Reduction Techniques ◽  
Reduction Methods ◽  
The Individual ◽  
Low Dimensional

AbstractTo solve key biomedical problems, experimentalists now routinely measure millions or billions of features (dimensions) per sample, with the hope that data science techniques will be able to build accurate data-driven inferences. Because sample sizes are typically orders of magnitude smaller than the dimensionality of these data, valid inferences require finding a low-dimensional representation that preserves the discriminating information (e.g., whether the individual suffers from a particular disease). There is a lack of interpretable supervised dimensionality reduction methods that scale to millions of dimensions with strong statistical theoretical guarantees. We introduce an approach to extending principal components analysis by incorporating class-conditional moment estimates into the low-dimensional projection. The simplest version, Linear Optimal Low-rank projection, incorporates the class-conditional means. We prove, and substantiate with both synthetic and real data benchmarks, that Linear Optimal Low-Rank Projection and its generalizations lead to improved data representations for subsequent classification, while maintaining computational efficiency and scalability. Using multiple brain imaging datasets consisting of more than 150 million features, and several genomics datasets with more than 500,000 features, Linear Optimal Low-Rank Projection outperforms other scalable linear dimensionality reduction techniques in terms of accuracy, while only requiring a few minutes on a standard desktop computer.

scholarly journals An efficient training scheme for supermodels

2017 ◽  
Vol 8 (2) ◽  
pp. 429-438 ◽  
Author(s):  
Francine J. Schevenhoven ◽  
Frank M. Selten
Keyword(s):  
Climate Models ◽  
State Of The Art ◽  
Atmospheric Model ◽  
High Dimensional ◽  
Model Errors ◽  
Global Atmospheric Model ◽  
Training Scheme ◽  
Skill Scores ◽  
Weather And Climate ◽  
The Individual

Abstract. Weather and climate models have improved steadily over time as witnessed by objective skill scores, although significant model errors remain. Given these imperfect models, predictions might be improved by combining them dynamically into a so-called supermodel. In this paper a new training scheme to construct such a supermodel is explored using a technique called cross pollination in time (CPT). In the CPT approach the models exchange states during the prediction. The number of possible predictions grows quickly with time, and a strategy to retain only a small number of predictions, called pruning, needs to be developed. The method is explored using low-order dynamical systems and applied to a global atmospheric model. The results indicate that the CPT training is efficient and leads to a supermodel with improved forecast quality as compared to the individual models. Due to its computational efficiency, the technique is suited for application to state-of-the art high-dimensional weather and climate models.

scholarly journals Short Spacing Synthesis from a Primary Beam Scanned Interferometer

1979 ◽  
Vol 49 ◽  
pp. 61-63
Author(s):  
R.D. Ekers ◽  
A.H. Rots
Keyword(s):  
Spectral Line ◽  
Line Profiles ◽  
Short Spacing ◽  
Physical Constraints ◽  
Uniform Sampling ◽  
Extended Sources ◽  
The Common ◽  
The Individual ◽  
Highly Uniform ◽  
Individual Line

Aperture synthesis instruments providing a generally highly uniform sampling of the visibility function often leave an unsampled hole near the origin of the (u,v)-plane. One of the common configurations of the Westerbork Synthesis Radio Telescope (WSRT) provides sampling in concentric rings with radii of n × 18 m. However, the samples with n=0 and n=1 cannot be obtained directly with the instrument because of rather obvious physical constraints. This missing short spacing information causes a central depression of the synthesized beam pattern, resulting in large negative, bowl shaped areas around (especially) extended sources. Very large sources will only partially be present in the maps. Annoying as this can be for continuum observations, in the case of spectral line data it causes serious distortions of the individual line profiles.

A Web-Based Virtual Research Environment for Marine Data

2020 ◽  
Author(s):  
Merret Buurman ◽  
Sebastian Mieruch ◽  
Alexander Barth ◽  
Charles Troupin ◽  
Peter Thijsse ◽  
...  
Keyword(s):  
User Interfaces ◽  
User Authentication ◽  
File Systems ◽  
User Interaction ◽  
Security Measures ◽  
Desktop Computer ◽  
Research Environment ◽  
Synchronization Mechanism ◽  
Virtual Research Environment ◽  
The Individual

<p>Like most areas of research, the marine sciences are undergoing an increased use of observational data from a multitude of sensors. As it is cumbersome to download, combine and process the increasing volume of data on the individual researcher's desktop computer, many areas of research turn to web- and cloud-based platforms. In the scope of the SeaDataCloud project, such a platform is being developed together with the EUDAT consortium.</p><p>The SeaDataCloud Virtual Research Environment (VRE) is designed to give researchers access to popular processing and visualization tools and to commonly used marine datasets of the SeaDataNet community. Some key aspects such as user authentication, hosting input and output data, are based on EUDAT services, with the perspective of integration into EOSC at a later stage.</p><p>The technical infrastructure is provided by five large EUDAT computing centres across Europe, where operational environments are heterogeneous and spatially far apart. The processing tools (pre-existing as desktop versions) are developed by various institutions of the SeaDataNet community. While some of the services interact with users via command line and can comfortably be exposed as JupyterNotebooks, many of them are very visual (e.g. user interaction with a map) and rely heavily on graphical user interfaces.</p><p>In this presentation, we will address some of the issues we encountered while building an integrated service out of the individual applications, and present our approaches to deal with them.</p><p>Heterogeneity in operational environments and dependencies is easily overcome by using Docker containers. Leveraging processing resources all across Europe is the most challenging part as yet. Containers are easily deployed anywhere in Europe, but the heavy dependence on (potentially shared) input data, and the possibility that the same data may be used by various services at the same time or in quick succession means that data synchronization across Europe has to take place at some point of the process. Designing a synchronization mechanism that does this without conflicts or inconsistencies, or coming up with a distribution scheme that minimizes the synchronization problem is not trivial.</p><p>Further issues came up during the adaptation of existing applications for server-based operation. This includes topics such as containerization, user authentication and authorization and other security measures, but also the locking of files, permissions on shared file systems and exploitation of increased hardware resources.</p>

scholarly journals Multimodel Prediction Skills of the Somali and Maritime Continent Cross-Equatorial Flows

2018 ◽  
Vol 31 (6) ◽  
pp. 2445-2464 ◽  
Author(s):  
Chen Li ◽  
Jing-Jia Luo ◽  
Shuanglin Li ◽  
Harry Hendon ◽  
Oscar Alves ◽  
...  
Keyword(s):  
High Resolution ◽  
Walker Circulation ◽  
Seasonal Prediction ◽  
Atmospheric Model ◽  
Precipitation Anomaly ◽  
Boreal Summer ◽  
Maritime Continent ◽  
Anomaly Correlation Coefficient ◽  
The Difference ◽  
The Individual

Predictive skills of the Somali cross-equatorial flow (CEF) and the Maritime Continent (MC) CEF during boreal summer are assessed using three ensemble seasonal forecasting systems, including the coarse-resolution Predictive Ocean Atmospheric Model for Australia (POAMA, version 2), the intermediate-resolution Scale Interaction Experiment–Frontier Research Center for Global Change (SINTEX-F), and the high-resolution seasonal prediction version of the Australian Community Climate and Earth System Simulator (ACCESS-S1) model. Retrospective prediction results suggest that prediction of the Somali CEF is more challenging than that of the MC CEF. While both the individual models and the multimodel ensemble (MME) mean show useful skill (with the anomaly correlation coefficient being above 0.5) in predicting the MC CEF up to 5-month lead, only ACCESS-S1 and the MME can skillfully predict the Somali CEF up to 2-month lead. Encouragingly, the CEF seesaw index (defined as the difference of the two CEFs as a measure of the negative phase relation between them) can be skillfully predicted up to 4–5 months ahead by SINTEX-F, ACCESS-S1, and the MME. Among the three models, the high-resolution ACCESS-S1 model generally shows the highest skill in predicting the individual CEFs, the CEF seesaw, as well as the CEF seesaw index–related precipitation anomaly pattern in Asia and northern Australia. Consistent with the strong influence of ENSO on the CEFs, the skill in predicting the CEFs depends on the model’s ability in predicting not only the eastern Pacific SST anomaly but also the anomalous Walker circulation that brings ENSO’s influence to bear on the CEFs.

Chaucer's Final -E

PMLA ◽  
1948 ◽  
Vol 63 (4) ◽  
pp. 1101-1124 ◽  
Author(s):  
E. Talbot Donaldson
Keyword(s):  
The Subject ◽  
The Individual ◽  
Individual Line

In an article published in this periodical Professor James G. Southworth has reopened the question of the pronunciation or non-pronunciation of Chaucer's unstressed -e in rhyme, and has come to the conclusion that this -e was not sounded in Chaucer's time, and should not now be sounded by readers of his poetry. With Professor Southworth's conclusion many students of Chaucer will undoubtedly sympathize. The modern ear is trained to hear poetry read for the sense as dictated by the syntax, and without regard for any claims that the individual line may have to being treated as a vocal unit distinct from its neighbors. Such a reading is often made difficult by the sounding of the final -e, which tends to prolong the pause. Yet despite the attractiveness of Professor Southworth's argument there are several aspects of it that should, in view of the importance of the subject, be examined in detail before we altogether abandon the -e in rhyme. To make such an examination is the purpose of this paper.

The Rod-and-Frame Effect: The Whole is Less than the Sum of its Parts

Perception ◽  
10.1068/p5411 ◽  
2005 ◽  
Vol 34 (6) ◽  
pp. 699-716 ◽  
Author(s):  
Wenxun Li ◽  
Leonard Matin
Keyword(s):  
Visual Perception ◽  
Mass Action ◽  
Induction Effect ◽  
Frame Effect ◽  
Object A ◽  
Tilted Frame ◽  
Additive Combination ◽  
The Individual ◽  
Rod And Frame ◽  
Individual Line

Since the discovery of the influence of the tilted frame on the visual perception of the orientation perceived as vertical (VPV), the frame has been treated as a unitary object—a Gestalt. We evaluated the effect of 1-line, 2-line, 3-line, and 4-line (square frame) stimuli of two different sizes, and asked whether the influence of the square frame on VPV is any greater than the additive combination of separate influences produced by the individual lines constituting the frame. We found that, for each size, the square frame is considerably less influential than the additive combination of the influences of the individual lines. The results conform to a mass action rule, in which the lengths and orientations of the individual line components are what matters and the organization of the lines into a square does not—no higher-level Gestalt property is involved in the induction effect on VPV.

scholarly journals Simulated and observed horizontal inhomogeneities of optical thickness of Arctic stratus

2018 ◽  
Author(s):  
Michael Schäfer ◽  
Katharina Loewe ◽  
André Ehrlich ◽  
Corinna Hoose ◽  
Manfred Wendisch
Keyword(s):  
Wind Velocity ◽  
Optical Thickness ◽  
Atmospheric Model ◽  
Sensitivity Study ◽  
Spectral Radiance ◽  
Small Scale ◽  
Airborne Measurements ◽  
Cloud Properties ◽  
The Individual ◽  
Horizontal Inhomogeneity

Abstract. Two-dimensional (2D) horizontal fields of cloud optical thickness derived from airborne measurements of solar spectral radiance during the Vertical Distribution of Ice in Arctic Clouds (VERDI) campaign (carried out in Inuvik, Canada in April/May 2012) are compared with semi–idealized Large Eddy Simulations (LES) of Arctic stratus performed with the COnsortium for Small-Scale MOdeling (COSMO) atmospheric model. The input for the LES is obtained from collocated airborne dropsonde observations. Four consecutive days of a persistent Arctic stratus observed above the sea–ice free Beaufort Sea are selected for the comparison. Macrophysical cloud properties such as cloud top altitude and vertical extent are well captured by COSMO. Cloud horizontal inhomogeneity quantified by the standard deviation and one-dimensional (1D) inhomogeneity parameters show that COSMO produces only half of the measured horizontal cloud inhomogeneities, while the directional structure of the cloud inhomogeneity is well represented by the model. Differences between the individual cases are mainly associated with the wind shear near cloud top and the vertical structure of the atmospheric boundary layer. A sensitivity study changing the wind velocity in COSMO by a vertically constant scaling factor shows that the directional cloud inhomogeneity structures strongly depend on the mean wind speed. A threshold wind velocity is identified, which determines when the cloud inhomogeneity stops increasing with increasing wind velocity.

scholarly journals Simulated and observed horizontal inhomogeneities of optical thickness of Arctic stratus

2018 ◽  
Vol 18 (17) ◽  
pp. 13115-13133 ◽  
Author(s):  
Michael Schäfer ◽  
Katharina Loewe ◽  
André Ehrlich ◽  
Corinna Hoose ◽  
Manfred Wendisch
Keyword(s):  
Wind Velocity ◽  
Optical Thickness ◽  
Large Scale ◽  
Atmospheric Model ◽  
Sensitivity Study ◽  
Small Scale ◽  
Airborne Measurements ◽  
Cloud Properties ◽  
Scale Structures ◽  
The Individual

Abstract. Two-dimensional horizontal fields of cloud optical thickness τ derived from airborne measurements of solar spectral, cloud-reflected radiance are compared with semi-idealized large eddy simulations (LESs) of Arctic stratus performed with the Consortium for Small-scale Modeling (COSMO) atmospheric model. The measurements were collected during the Vertical Distribution of Ice in Arctic Clouds (VERDI) campaign carried out in Inuvik, Canada, in April/May 2012. The input for the LESs is obtained from collocated airborne dropsonde observations of a persistent Arctic stratus above the sea-ice-free Beaufort Sea. Simulations are performed for spatial resolutions of 50 m (1.6 km × 1.6 km domain) and 100 m (6.4 km × 6.4 km domain). Macrophysical cloud properties, such as cloud top altitude and vertical extent, are well captured by the COSMO simulations. However, COSMO produces rather homogeneous clouds compared to the measurements, in particular for the simulations with coarser spatial resolution. For both spatial resolutions, the directional structure of the cloud inhomogeneity is well represented by the model. Differences between the individual cases are mainly associated with the wind shear near cloud top and the vertical structure of the atmospheric boundary layer. A sensitivity study changing the wind velocity in COSMO by a vertically constant scaling factor shows that the directional, small-scale cloud inhomogeneity structures can range from 250 to 800 m, depending on the mean wind speed, if the simulated domain is large enough to capture also large-scale structures, which then influence the small-scale structures. For those cases, a threshold wind velocity is identified, which determines when the cloud inhomogeneity stops increasing with increasing wind velocity.

scholarly journals Graded IR Filters: Distinguishing Between Single and Multipoint NO2···I Halogen Bonded Supramolecular Synthons (P, Q, and R Synthons)

2014 ◽  
Vol 67 (12) ◽  
pp. 1840 ◽  
Author(s):  
Subhankar Saha ◽  
Somnath Ganguly ◽  
Gautam R. Desiraju
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Structure Prediction ◽  
Crystal Structure Prediction ◽  
Supramolecular Synthon ◽  
High Throughput Analysis ◽  
Disordered Structures ◽  
Recognition Pattern ◽  
The Individual ◽  
Ir Spectroscopic

The NO2···I supramolecular synthon is a halogen bonded recognition pattern that is present in the crystal structures of many compounds that contain these functional groups. These synthons have been previously distinguished as P, Q, and R types using topological and geometrical criteria. A five step IR spectroscopic sequence is proposed here to distinguish between these synthon types in solid samples. Sets of known compounds that contain the P, Q, and R synthons are first taken to develop IR spectroscopic identifiers for them. The identifiers are then used to create graded IR filters that sieve the synthons. These filters contain signatures of the individual NO2···I synthons and may be applied to distinguish between P, Q, and R synthon varieties. They are also useful to identify synthons that are of a borderline character, synthons in disordered structures wherein the crystal structure in itself is not sufficient to distinguish synthon types, and in the identification of the NO2···I synthons in compounds with unknown crystal structures. This study establishes clear differences for the three different geometries P, Q, and R and in the chemical differences in the intermolecular interactions contained in the synthons. Our IR method can be conveniently employed when single crystals are not readily available also in high throughput analysis. It is possible that such identification may also be adopted as an input for crystal structure prediction analysis of compounds with unknown crystal structures.

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