scholarly journals Excitation of Polar Motion

2000 ◽  
Vol 178 ◽  
pp. 411-420 ◽  
Author(s):  
Clark R. Wilson
Keyword(s):  
Polar Motion ◽  
Conceptual Models ◽  
Numerical Models ◽  
Broad Band ◽  
Quality Data ◽  
Past Century ◽  
High Quality Data ◽  
The Past ◽  
Continuum Concept ◽  
The Continuum

AbstractConceptual models of polar motion have evolved over the past century, as improved data revealed signals over progressively wider frequency bands. In the 1890s, Chandler represented polar motion as a sum of discrete components, 14 month and annual terms, and this component model effectively summarized the observations, but did not provide a physical explanation for them. Over time both the search for a physical understanding of polar motion, and the ability to observe the broad band continuum outside the Chandler and annual bands have led to an understanding of polar motion as a continuum of variations, not adequately described by a few discrete components. The continuum concept is now the working model in most studies of polar motion. The transition from component to continuum conceptual models preceded the arrival of high quality data by several decades, and reflected significant contributions from Harold Jeffreys. With modern space geodetic observations and good global numerical models of the atmosphere, oceans, and other climate processes, it is clear that air and water motion and redistribution are the dominant contributors to the excitation continuum.

Lessons Learned from Modal Testing of Aerospace Structures

1993 ◽  
Vol 36 (1) ◽  
pp. 49-56
Author(s):  
David Hunt ◽  
Ralph Brillhart
Keyword(s):  
Data Acquisition ◽  
Lessons Learned ◽  
Modal Testing ◽  
Quality Data ◽  
High Quality Data ◽  
Modal Data ◽  
Analysis Techniques ◽  
Rapid Acquisition ◽  
The Past ◽  
Multiple Input

A wide variety of challenges have been encountered during the past 10 years of aerospace modal testing. New excitation methods have evolved, including single and multiple input random. Enhancements to traditional single and multiple input sine methods have been developed. Data analysis techniques that allow more consistent modal models to be extracted in less time than previously required have also been developed. New data acquisition hardware allows more rapid acquisition of modal data. As a result of these new excitation methods, data acquisition hardware and analysis tools, more high-quality data can be collected in considerably less time than was possible in the past. Modal surveys with 200 to 400 channels of response are becoming more commonplace. During the development and implementation of these new capabilities, many lessons have been learned about how to manage the increased amount of data collected and how to ensure that the quality remains high.

scholarly journals Review of Sand Production Prediction Models

2013 ◽  
Vol 2013 ◽  
pp. 1-16 ◽  
Author(s):  
Hossein Rahmati ◽  
Mahshid Jafarpour ◽  
Saman Azadbakht ◽  
Alireza Nouri ◽  
Hans Vaziri ◽  
...  
Keyword(s):  
Oil And Gas ◽  
Prediction Models ◽  
Numerical Models ◽  
Element Model ◽  
Reservoir Rock ◽  
Sand Production ◽  
The Past ◽  
Short Period ◽  
Analytical Formulae ◽  
The Continuum

Sand production in oil and gas wells can occur if fluid flow exceeds a certain threshold governed by factors such as consistency of the reservoir rock, stress state and the type of completion used around the well. The amount of solids can be less than a few grams per cubic meter of reservoir fluid, posing only minor problems, or a substantial amount over a short period of time, resulting in erosion and in some cases filling and blocking of the wellbore. This paper provides a review of selected approaches and models that have been developed for sanding prediction. Most of these models are based on the continuum assumption, while a few have recently been developed based on discrete element model. Some models are only capable of assessing the conditions that lead to the onset of sanding, while others are capable of making volumetric predictions. Some models use analytical formulae, particularly those for estimating the onset of sanding while others use numerical models, particularly in calculating sanding rate. Although major improvements have been achieved in the past decade, sanding tools are still unable to predict the sand mass and the rate of sanding for all field problems in a reliable form.

scholarly journals Immune Signatures in Patients with Psoriasis Vulgaris of Blood-Heat Syndrome: A Systematic Review and Meta-Analysis

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Xin Li ◽  
Qing-qing Xiao ◽  
Fu-lun Li ◽  
Rong Xu ◽  
Bin Fan ◽  
...  
Keyword(s):  
Psoriasis Vulgaris ◽  
Meta Analysis ◽  
Serum Marker ◽  
Serum Markers ◽  
Quality Data ◽  
Healthy Controls ◽  
High Quality Data ◽  
The Past ◽  
Before And After ◽  
Heat Syndrome

Objective. To determine whether immunological serum markers IFN-γ, IL-4, IL-17, IL-23, IL-6, TNF-α, and IL-10 are elevated or decreased in patients compared with healthy controls.Methods. A complete search of the literature on this topic within the past 30 years was conducted across seven databases. Seventeen studies including 768 individuals were identified. Differences in serum marker levels between subjects and controls were pooled as MDs using the random-effects model.Results. The pooled MDs were higher in patients than in healthy controls for IFN-γ(MD 24.9, 95% CI 12.36–37.43), IL-17 (MD 28.92, 95% CI 17.44–40.40), IL-23 (MD 310.60, 95% CI 4.96–616.24), and TNF-α(MD 19.84, 95% CI 13.80–25.87). Pooled IL-4 (MD −13.5, 95% CI −17.74–−9.26) and IL-10 (MD −10.33, 95% CI −12.03–−8.63) levels were lower in patients.Conclusion. The pooled analyses suggest that levels of IFN-γ, IL-17, IL-23, and TNF-αare significantly elevated and that levels of IL-4 and IL-10 are significantly decreased in sera of patients with psoriasis vulgaris of blood-heat syndrome. Measuring progression of blood-heat syndrome of psoriasis vulgaris will require additional high-quality data, with a low risk of bias and adequate sample sizes, before and after antipsoriatic therapy.

A seminal paper on the epidemiology of cancer pain

2018 ◽  
Author(s):  
Paul Farquhar-Smith
Keyword(s):  
Cancer Pain ◽  
Quality Data ◽  
High Quality ◽  
High Quality Data ◽  
Seminal Paper ◽  
Patients With Cancer ◽  
The Past ◽  
Pain Prevalence ◽  
Prevalence Of Pain ◽  
Interest In Research

The landmark paper discussed in this chapter is ‘Prevalence of pain in patients with cancer: A systematic review of the past 40 years’, published by van den Beuken et al. in 2007. It is not surprising that this definitive study on cancer pain prevalence is one of the most cited papers in cancer pain. Despite the extent of cancer pain literature, this paper’s 2007 publication is surprisingly recent for the first methodologically sound and major study of cancer pain prevalence. Many previous estimates lacked accuracy, and were prone to bias. What was known was that, despite apparent increasing interest in, research in, and recognition of pain in cancer patients, the prevalence of such pain was still high, even after treatment. This paper attempted to accurately quantify just how high by statistically pooling available high-quality data while avoiding the pitfalls of combining heterogeneous studies, as had plagued previous reports.

scholarly journals pH-sensitive vibrational probe reveals a cytoplasmic protonated cluster in bacteriorhodopsin

2017 ◽  
Vol 114 (51) ◽  
pp. E10909-E10918 ◽  
Author(s):  
Victor A. Lorenz-Fonfria ◽  
Mattia Saita ◽  
Tzvetana Lazarova ◽  
Ramona Schlesinger ◽  
Joachim Heberle
Keyword(s):  
Proton Transfer ◽  
Broad Band ◽  
Transfer Reactions ◽  
Molecular Processes ◽  
Proton Release ◽  
The Past ◽  
Carboxylic Groups ◽  
Proton Transfer Reactions ◽  
Proton Uptake ◽  
The Continuum

Infrared spectroscopy has been used in the past to probe the dynamics of internal proton transfer reactions taking place during the functional mechanism of proteins but has remained mostly silent to protonation changes in the aqueous medium. Here, by selectively monitoring vibrational changes of buffer molecules with a temporal resolution of 6 µs, we have traced proton release and uptake events in the light-driven proton-pump bacteriorhodopsin and correlate these to other molecular processes within the protein. We demonstrate that two distinct chemical entities contribute to the temporal evolution and spectral shape of the continuum band, an unusually broad band extending from 2,300 to well below 1,700 cm−1. The first contribution corresponds to deprotonation of the proton release complex (PRC), a complex in the extracellular domain of bacteriorhodopsin where an excess proton is shared by a cluster of internal water molecules and/or ionic E194/E204 carboxylic groups. We assign the second component of the continuum band to the proton uptake complex, a cluster with an excess proton reminiscent to the PRC but located in the cytoplasmic domain and possibly stabilized by D38. Our findings refine the current interpretation of the continuum band and call for a reevaluation of the last proton transfer steps in bacteriorhodopsin.

scholarly journals DO WE NEED PRE-STORM SURVEYED BATHYMETRY FOR OPERATIONAL EROSION FORECASTING? EVALUATION OF REPRESENTATIVE AND SYNTHETIC BATHYMETRY ALTERNATIVES

2020 ◽  
pp. 13
Author(s):  
Nashwan Matheen ◽  
Mitchell D. Harley ◽  
Ian L.Turner ◽  
Joshua A. Simmons ◽  
Mandi Thran
Keyword(s):  
Coastal Erosion ◽  
Numerical Models ◽  
Early Warning Systems ◽  
Quality Data ◽  
Warning Systems ◽  
Storm Events ◽  
Coastal Hazard ◽  
High Quality Data ◽  
Forecasting Evaluation ◽  
Hydrographic Surveying

Immediate pre-storm bathymetry is a key input required for numerical models used in coastal hazard Early Warning Systems. However, the expense and challenging nature of hydrographic surveying means that the availability of high-quality data is extremely rare. This study evaluates the extent to which synthetic and representative bathymetry alternatives can be used to obtain reliable predictions of storm induced sub-aerial erosion using the XBeach coastal erosion numerical model. Multiple storm events at 2 contrasting sites are modelled using 6 bathymetry scenarios including pre-storm surveyed bathymetries, an average bathymetry, and Dean profiles. The output is analysed to evaluate the skill of XBeach erosion predictions as a function of the bathymetry used.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/bE3aXVXxZqQ

scholarly journals Selective Editing: A Quest for Efficiency and Data Quality

2013 ◽  
Vol 29 (4) ◽  
pp. 473-488 ◽  
Author(s):  
Ton de Waal
Keyword(s):  
Statistical Data ◽  
Quality Data ◽  
Future Research ◽  
High Quality ◽  
High Quality Data ◽  
The Past ◽  
Usual Form ◽  
Data Editing ◽  
Data Record ◽  
Editing Process

Abstract National statistical institutes are responsible for publishing high quality statistical information on many different aspects of society. This task is complicated considerably by the fact that data collected by statistical offices often contain errors. The process of correcting errors is referred to as statistical data editing. For many years this has been a purely manual process, with people checking the collected data record by record and correcting them if necessary. For this reason the data editing process has been both expensive and time-consuming. This article sketches some of the important methodological developments aiming to improve the efficiency of the data editing process that have occurred during the past few decades. The article focuses on selective editing, which is based on an idea rather shocking for people working in the production of high-quality data: that it is not necessary to find and correct all errors. Instead of trying to correct all errors, it generally suffices to correct only those errors where data editing has substantial influence on publication figures. This overview article sketches the background of selective editing, describes the most usual form of selective editing up to now, and discusses the contributions to this special issue of the Journal of Official Statistics on selective editing. The article concludes with describing some possible directions for future research on selective editing and statistical data editing in general.

Spin reversal of the rattleback: theory and experiment

1988 ◽  
Vol 418 (1854) ◽  
pp. 165-197 ◽  
Keyword(s):  
Numerical Model ◽  
Numerical Models ◽  
Spin Model ◽  
The Body ◽  
Past Century ◽  
Spin Direction ◽  
The Past ◽  
Spin Reversal ◽  
Observed Behaviour ◽  
Theory And Experiment

The behaviour of a top known variously as the rattleback, celt or wobblestone is studied. When spun on a flat, smooth, horizontal surface, self-induced oscillations about a horizontal axis eventually consume the initial spin energy; once the spinning has ceased, the oscillations decay and the body spins in the opposite direction. Many rattlebacks seem to be spin biased, reversing spin direction only once and only if the initial spin has the proper sense; others reverse readily from either initial spin direction. Analysis and simulation papers appearing over the past century have attempted, respectively, to explain and qualitatively predict the top’s possible behaviours, and to reconcile observed behaviour with various numerical models. In this work, the two broad theories proposed to explain the spin bias, one which neglects slipping and dissipation and one which incorporates these effects, are critically investigated by several means. The validity of the no-slip assumption is questioned. A numerical model which allows for aerodynamic effects and dry friction due to spinning and slipping is developed. The complicated equations of the numerical model are simplified by analysing the transfer of energy between the spin and oscillations. A comprehensive explanation of the behaviour based on this simplified spin model and the realistic limits of the no-slip motion is proposed. Finally, the predictions of the ‘complete’ numerical model and the simplified model are compared with experimental data.

scholarly journals Epidemiology, Natural History, and Clinical Presentation of Large Vessel Ischemic Stroke

Neurosurgery ◽  
2019 ◽  
Vol 85 (suppl_1) ◽  
pp. S4-S8 ◽  
Author(s):  
Robert C Rennert ◽  
Arvin R Wali ◽  
Jeffrey A Steinberg ◽  
David R Santiago-Dieppa ◽  
Scott E Olson ◽  
...  
Keyword(s):  
Natural History ◽  
Clinical Presentation ◽  
Treatment Algorithm ◽  
Large Vessel ◽  
Quality Data ◽  
High Quality Data ◽  
Endovascular Thrombectomy ◽  
The Past ◽  
Intravenous Tissue Plasminogen Activator ◽  
Tissue Plasminogen

Abstract Large vessel occlusions (LVOs), variably defined as blockages of the proximal intracranial anterior and posterior circulation, account for approximately 24% to 46% of acute ischemic strokes. Commonly refractory to intravenous tissue plasminogen activator (tPA), LVOs place large cerebral territories at ischemic risk and cause high rates of morbidity and mortality without further treatment. Over the past few years, an abundance of high-quality data has demonstrated the efficacy of endovascular thrombectomy for improving clinical outcomes in patients with LVOs, transforming the treatment algorithm for affected patients. In this review, we discuss the epidemiology, pathophysiology, natural history, and clinical presentation of LVOs as a framework for understanding the recent clinical strides of the endovascular era.

scholarly journals The state of the art in helioseismic ground-based experiments

1997 ◽  
Vol 181 ◽  
pp. 15-29
Author(s):  
Pere L. Pallé
Keyword(s):  
Solar Cycle ◽  
State Of The Art ◽  
Quality Data ◽  
Direct Impact ◽  
High Quality ◽  
High Quality Data ◽  
The Past ◽  
Long Time ◽  
Inversion Techniques ◽  
And Inversion

The new results obtained from the observation of solar oscillations over the past decade, have a direct impact on our knowledge of the Sun's interior. As a consequence, a great interest in helioseismology has arisen and is reflected in the development of new observational projects as well as new analyse and inversion techniques. In this review we will describe the present ground-based observational programmes, which, unlike the space ones, are mostly designed to produce high quality data over very long time spans (up to solar cycle time scales). The characteristics of the various observational programmes, single-site and network, will be described together with their performances, the main results obtained up to now, and some other logistical aspects.

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