Insidious errors in dipole parameters due to shell model misspecification using multiple time-points

1994 ◽  
Vol 6 (4) ◽  
pp. 283-298 ◽  
Author(s):  
Zhi Zhang ◽  
Don L. Jewett ◽  
Gilbert Goodwill
Keyword(s):  
Shell Model ◽  
Model Misspecification ◽  
Multiple Time ◽  
Time Points ◽  
Dipole Parameters ◽  
Multiple Time Points

scholarly journals Use of TanDEM-X and SRTM-C Data for Detection of Deforestation Caused by Bark Beetle in Central European Mountains

2021 ◽  
Vol 13 (15) ◽  
pp. 3042
Author(s):  
Kateřina Gdulová ◽  
Jana Marešová ◽  
Vojtěch Barták ◽  
Marta Szostak ◽  
Jaroslav Červenka ◽  
...  
Keyword(s):  
Bark Beetle ◽  
Synergistic Effects ◽  
Canopy Height ◽  
Surface Model ◽  
Multiple Time ◽  
Central European ◽  
Time Points ◽  
Bohemian Forest ◽  
Multiple Time Points ◽  
Surrounding Areas

The availability of global digital elevation models (DEMs) from multiple time points allows their combination for analysing vegetation changes. The combination of models (e.g., SRTM and TanDEM-X) can contain errors, which can, due to their synergistic effects, yield incorrect results. We used a high-resolution LiDAR-derived digital surface model (DSM) to evaluate the accuracy of canopy height estimates of the aforementioned global DEMs. In addition, we subtracted SRTM and TanDEM-X data at 90 and 30 m resolutions, respectively, to detect deforestation caused by bark beetle disturbance and evaluated the associations of their difference with terrain characteristics. The study areas covered three Central European mountain ranges and their surrounding areas: Bohemian Forest, Erzgebirge, and Giant Mountains. We found that vertical bias of SRTM and TanDEM-X, relative to the canopy height, is similar with negative values of up to −2.5 m and LE90s below 7.8 m in non-forest areas. In forests, the vertical bias of SRTM and TanDEM-X ranged from −0.5 to 4.1 m and LE90s from 7.2 to 11.0 m, respectively. The height differences between SRTM and TanDEM-X show moderate dependence on the slope and its orientation. LE90s for TDX-SRTM differences tended to be smaller for east-facing than for west-facing slopes, and varied, with aspect, by up to 1.5 m in non-forest areas and 3 m in forests, respectively. Finally, subtracting SRTM and NASA DEMs from TanDEM-X and Copernicus DEMs, respectively, successfully identified large areas of deforestation caused by hurricane Kyril in 2007 and a subsequent bark beetle disturbance in the Bohemian Forest. However, local errors in TanDEM-X, associated mainly with forest-covered west-facing slopes, resulted in erroneous identification of deforestation. Therefore, caution is needed when combining SRTM and TanDEM-X data in multitemporal studies in a mountain environment. Still, we can conclude that SRTM and TanDEM-X data represent suitable near global sources for the identification of deforestation in the period between the time points of their acquisition.

Meta-analysis of effect sizes reported at multiple time points: A multivariate approach

2012 ◽  
Vol 9 (5) ◽  
pp. 610-620 ◽  
Author(s):  
Thomas A Trikalinos ◽  
Ingram Olkin
Keyword(s):  
Random Effects ◽  
Treatment Effects ◽  
Multivariate Analyses ◽  
Meta Analysis ◽  
Effect Sizes ◽  
Multiple Time ◽  
Time Points ◽  
Fixed And Random Effects ◽  
Multiple Time Points ◽  
Meta Analyses

Background Many comparative studies report results at multiple time points. Such data are correlated because they pertain to the same patients, but are typically meta-analyzed as separate quantitative syntheses at each time point, ignoring the correlations between time points. Purpose To develop a meta-analytic approach that estimates treatment effects at successive time points and takes account of the stochastic dependencies of those effects. Methods We present both fixed and random effects methods for multivariate meta-analysis of effect sizes reported at multiple time points. We provide formulas for calculating the covariance (and correlations) of the effect sizes at successive time points for four common metrics (log odds ratio, log risk ratio, risk difference, and arcsine difference) based on data reported in the primary studies. We work through an example of a meta-analysis of 17 randomized trials of radiotherapy and chemotherapy versus radiotherapy alone for the postoperative treatment of patients with malignant gliomas, where in each trial survival is assessed at 6, 12, 18, and 24 months post randomization. We also provide software code for the main analyses described in the article. Results We discuss the estimation of fixed and random effects models and explore five options for the structure of the covariance matrix of the random effects. In the example, we compare separate (univariate) meta-analyses at each of the four time points with joint analyses across all four time points using the proposed methods. Although results of univariate and multivariate analyses are generally similar in the example, there are small differences in the magnitude of the effect sizes and the corresponding standard errors. We also discuss conditional multivariate analyses where one compares treatment effects at later time points given observed data at earlier time points. Limitations Simulation and empirical studies are needed to clarify the gains of multivariate analyses compared with separate meta-analyses under a variety of conditions. Conclusions Data reported at multiple time points are multivariate in nature and are efficiently analyzed using multivariate methods. The latter are an attractive alternative or complement to performing separate meta-analyses.

THE ROLE OF MEMORY PERSPECTIVE IN SOCIAL PHOBIA: IMMEDIATE AND DELAYED MEMORIES FOR ROLE-PLAYED SITUATIONS

2002 ◽  
Vol 30 (4) ◽  
pp. 415-425 ◽  
Author(s):  
Meredith E. Coles ◽  
Cynthia L. Turk ◽  
Richard G. Heimberg
Keyword(s):  
Social Phobia ◽  
Multiple Time ◽  
Behavioral Models ◽  
Social Situations ◽  
Time Points ◽  
Cognitive Behavioral Models ◽  
Multiple Time Points ◽  
Memory Perspective ◽  
Field Perspective

Cognitive-behavioral models (Clark & Wells, 1995; Rapee & Heimberg, 1997) and recent research suggest that individuals with social phobia (SP) experience both images (Hackmann, Surawy, & Clark, 1998) and memories (Coles, Turk, Heimberg, & Fresco, 2001; Wells, Clark, & Ahmad, 1998) of anxiety-producing social situations from an observer perspective. The current study examines memory perspective for two role-played situations (speech and social interaction) at multiple time points (immediate and 3 weeks post) in 22 individuals with generalized SP and 30 non-anxious controls (NACs). At both time points, SPs recalled the role-plays from a more observer/less field perspective than did NACs. Further, over time, the memory perspective of SPs became even more observer/less field while the memory perspective of NAC remained relatively stable.

The Silicon Peaches

2021 ◽  
pp. 31-42
Author(s):  
Dan Breznitz
Keyword(s):  
Information And Communication Technologies ◽  
Silicon Valley ◽  
Communication Technologies ◽  
Multiple Time ◽  
Rapid Rise ◽  
Time Points ◽  
Start Up ◽  
Information And Communication ◽  
Multiple Time Points ◽  
Start Ups

This chapter acknowledges that, for many regions, the idea of attracting cutting-edge tech start-ups is almost irresistible. Seemingly every community aspires to become the next Silicon Valley. But is that feasible? This chapter make these lessons concrete by elaborating on the rapid rise and, even faster and deeper, decline of America’s first Silicon Valley—Cleveland, Ohio. It then shows the near impossibility of trying to become the next Silicon Valley by analyzing the mysterious failure of Atlanta, Georgia—a city that diligently followed all the advice ever given to an aspiring new start-up hub, but somehow was always left only with the “potential.” We will see how at multiple time-points Atlanta’s companies were the leading innovators with the best products in the newest information and communication technologies (ICT), only to falter and be taken over by Silicon Valley companies without leaving any apparent impact on the region. It then brings in social-network research and the concept of embeddedness to explain why trying to recreate a Silicon Valley is a doomed (and expensive) enterprise.

A porcine model of relief of unilateral ureteral obstruction: study on self-repairing capability over multiple time points

2016 ◽  
Vol 419 (1-2) ◽  
pp. 115-123 ◽  
Author(s):  
Yingying Liu ◽  
Jing Sun ◽  
Lining Miao ◽  
Lei Ji ◽  
Manyu Luo ◽  
...  
Keyword(s):  
Ureteral Obstruction ◽  
Porcine Model ◽  
Unilateral Ureteral Obstruction ◽  
Multiple Time ◽  
Time Points ◽  
Multiple Time Points

scholarly journals Optimizing the diagnostic power with gastric emptying scintigraphy at multiple time points

2011 ◽  
Vol 11 (1) ◽  
Author(s):  
Qingjiang Hou ◽  
Zhiyue Lin ◽  
Reginald Dusing ◽  
Byron J Gajewski ◽  
Richard W McCallum ◽  
...  
Keyword(s):  
Gastric Emptying ◽  
Multiple Time ◽  
Gastric Emptying Scintigraphy ◽  
Time Points ◽  
Diagnostic Power ◽  
Multiple Time Points

Many multipotential gene-marked progenitor or stem cell clones contribute to hematopoiesis in nonhuman primates

Blood ◽  
2000 ◽  
Vol 96 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Hyeoung Joon Kim ◽  
John F. Tisdale ◽  
Tong Wu ◽  
Masaaki Takatoku ◽  
Stephanie E. Sellers ◽  
...  
Keyword(s):  
Gene Transfer ◽  
Insertion Site ◽  
Autologous Transplantation ◽  
Multiple Time ◽  
Site Analysis ◽  
Time Points ◽  
Macaque Model ◽  
Multiple Time Points ◽  
High Level ◽  
Large Animals

Retroviral insertion site analysis was used to track the contribution of retrovirally transduced primitive progenitors to hematopoiesis after autologous transplantation in the rhesus macaque model. CD34-enriched mobilized peripheral blood cells were transduced with retroviral marking vectors containing the neo gene and were reinfused after total body irradiation. High-level gene transfer efficiency allowed insertion site analysis of individual myeloid and erythroid colony-forming units (CFU) and of highly purified B- and T-lymphoid populations in 2 animals. At multiple time points up to 1 year after transplantation, retroviral insertion sites were identified by performing inverse polymerase chain reaction and sequencing vector-containing CFU or more than 99% pure T- and B-cell populations. Forty-eight unique insertion sequences were detected in the first animal and also in the second animal, and multiple clones contributed to hematopoiesis at 2 or more time points. Multipotential clones contributing to myeloid and lymphoid lineages were identified. These results support the concept that hematopoiesis in large animals is polyclonal and that individual multipotential stem or progenitor cells can contribute to hematopoiesis for prolonged periods. Gene transfer to long-lived, multipotent clones is shown and is encouraging for human gene therapy applications.

Sample Size Calculation for Thorough QT/QTc Study Considering Various Factors Related to Multiple Time Points

2010 ◽  
Vol 20 (3) ◽  
pp. 580-594 ◽  
Author(s):  
Zhaoling Meng ◽  
Robert Kringle ◽  
Xun Chen ◽  
Peng-Liang Zhao
Keyword(s):  
Sample Size ◽  
Sample Size Calculation ◽  
Multiple Time ◽  
Time Points ◽  
Multiple Time Points

A systematic review of the methodologies used in research related to adult drug and alcohol rehabilitation in therapeutic communities published 2000-2013

2015 ◽  
Vol 36 (4) ◽  
pp. 193-208 ◽  
Author(s):  
Cassandra Perryman ◽  
Genevieve Dingle
Keyword(s):  
Systematic Review ◽  
Psychiatric Symptoms ◽  
Well Being ◽  
Size Analysis ◽  
Multiple Time ◽  
Therapeutic Communities ◽  
Diverse Range ◽  
Content Type ◽  
Time Points ◽  
Multiple Time Points

Purpose – The purpose of this paper is to summarize research conducted in long-term residential rehabilitation centers, including therapeutic communities (TCs), in order to further clarify the effectiveness of this treatment approach and to evaluate the quality of TC research conducted in the period 2000-2013. Design/methodology/approach – The composite search engine UQ database Summon were used to find articles with “Therapeutic Community” as title words, and the search was limited to adult participants, peer-reviewed articles, published between January 2000 and June 2013 in the English language. The review was conducted using Cochrane Collaboration methods and reported under the Preferred Reporting Items for Systematic Review and Meta-analyses guidelines. Findings – In total, 25 studies met inclusion criteria for the review and represented data from n=5,923 participants in the USA, Australia, Spain, England, and Belgium. Evidence supports the TC approach for a diverse range of individuals who misuse a range of substances. Several studies reported a relationship between retention and outcomes however dropout from treatment is a widespread issue. A paucity of research using multiple time points precludes any firm conclusions regarding the optimal length of treatment in a TC. There is a lack of research on the interplay between individual and community-level factors on client well-being, retention, and longer term outcomes. Research limitations/implications – This review highlights the need for TC research that includes multiple time points and follow-up assessments, and measures of change in theoretically meaningful constructs alongside standard measures of demographics, substance use, and psychiatric symptoms. Practical implications – The reporting format of TC research should be better standardized in order to create a better basis for research comparison. More standardized reporting would also allow for effect size analysis, and create a more efficacious evidence base. Originality/value – This updates the systematic review body of research.

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