20 research outputs found

    Zero- vs. one-dimensional, parametric vs. non-parametric, and confidence interval vs. hypothesis testing procedures in one-dimensional biomechanical trajectory analysis.

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    Biomechanical processes are often manifested as one-dimensional (1D) trajectories. It has been shown that 1D confidence intervals (CIs) are biased when based on 0D statistical procedures, and the non-parametric 1D bootstrap CI has emerged in the Biomechanics literature as a viable solution. The primary purpose of this paper was to clarify that, for 1D biomechanics datasets, the distinction between 0D and 1D methods is much more important than the distinction between parametric and non-parametric procedures. A secondary purpose was to demonstrate that a parametric equivalent to the 1D bootstrap exists in the form of a random field theory (RFT) correction for multiple comparisons. To emphasize these points we analyzed six datasets consisting of force and kinematic trajectories in one-sample, paired, two-sample and regression designs. Results showed, first, that the 1D bootstrap and other 1D non-parametric CIs were qualitatively identical to RFT CIs, and all were very different from 0D CIs. Second, 1D parametric and 1D non-parametric hypothesis testing results were qualitatively identical for all six datasets. Last, we highlight the limitations of 1D CIs by demonstrating that they are complex, design-dependent, and thus non-generalizable. These results suggest that (i) analyses of 1D data based on 0D models of randomness are generally biased unless one explicitly identifies 0D variables before the experiment, and (ii) parametric and non-parametric 1D hypothesis testing provide an unambiguous framework for analysis when one׳s hypothesis explicitly or implicitly pertains to whole 1D trajectories.JOURNAL OF BIOMECHANICS. 48(7):1277-1285 (2015)journal articl

    Zero- vs. one-dimensional, parametric vs. non-parametric, and confidence interval vs. hypothesis testing procedures in one-dimensional biomechanical trajectory analysis.

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    Biomechanical processes are often manifested as one-dimensional (1D) trajectories. It has been shown that 1D confidence intervals (CIs) are biased when based on 0D statistical procedures, and the non-parametric 1D bootstrap CI has emerged in the Biomechanics literature as a viable solution. The primary purpose of this paper was to clarify that, for 1D biomechanics datasets, the distinction between 0D and 1D methods is much more important than the distinction between parametric and non-parametric procedures. A secondary purpose was to demonstrate that a parametric equivalent to the 1D bootstrap exists in the form of a random field theory (RFT) correction for multiple comparisons. To emphasize these points we analyzed six datasets consisting of force and kinematic trajectories in one-sample, paired, two-sample and regression designs. Results showed, first, that the 1D bootstrap and other 1D non-parametric CIs were qualitatively identical to RFT CIs, and all were very different from 0D CIs. Second, 1D parametric and 1D non-parametric hypothesis testing results were qualitatively identical for all six datasets. Last, we highlight the limitations of 1D CIs by demonstrating that they are complex, design-dependent, and thus non-generalizable. These results suggest that (i) analyses of 1D data based on 0D models of randomness are generally biased unless one explicitly identifies 0D variables before the experiment, and (ii) parametric and non-parametric 1D hypothesis testing provide an unambiguous framework for analysis when one׳s hypothesis explicitly or implicitly pertains to whole 1D trajectories

    Assessment of the endometriosis in the pelvis.

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    Úvod: Hlavním cílem naší práce bylo porovnat diagnostickou přesnost ultrazvukového vyšetření a magnetické rezonance (MR) při stanovení hluboké endometriózy (deep endometriosis) v pánvi při použití jednotného protokolu. Druhým cílem bylo stanovení křivky učení u lékaře ve výcviku (sonografisty a radiologa). Pro úvod do problematiky jsme publikovali 3 přehledové články o diagnostice a jeden přehledový článek o klasifikačních systémech rozsahu endometriózy prochází recenzním řízením. Metodika: Přehledové články byly psány formou systematického (kvalitativního) přehledového článku ("narrative review") vycházející z databáze PubMed a doporučení vědeckých společností. Účast ve vlastní výzkumné studii byla nabídnuta pacientkám odeslaným k operačnímu řešení hluboké endometriózy do Centra pro léčbu endometriózy. Pacientky v rámci protokolu podstoupily ultrazvukové a MR vyšetření zkušeným lékařem (dále jen expertem) a lékařem ve výcviku (dále jen non-expertem). Rozsah endometriózy byl popsán dle doporučení mezinárodní pracovní skupiny IDEA (International Deep Endometriosis Analysis group, 2016). Chirurgický a histologický nález byl použit jako referenční standard. Křivka učení byla stanovena jako zlepšení přesnosti ve stanovení rozsahu endometriózy ve 3 blocích, do kterých byly pacientky řazeny...Introduction: The main goal of our work was to compare the diagnostic accuracy of ultrasound examination and magnetic resonance imaging (MRI) in the assessment of deep endometriosis in the pelvis. Our second aim was to establish a learning curve of a sonographer and a radiologists (non-experts). As an introduction to the subject we have published 3 reviews on the diagnosis and one narrative review on the classification systems in the evaluation of endometriosis has been submitted for publication. Methodology: Reviews were written as narrative reviews based on PubMed search and scientific societies recommendations. We have offered participation to all patients in the endometriosis centre with high suspicion of deep endometriosis, who then underwent examination by ultrasound and MRI by expert and non-expert before their surgical treatment, all findings described according to the consensus IDEA (international Deep Endometriosis Analysis group, 2016). Surgical and histological findings were used as a reference standard. Learning curve was defined as an improvement in accuracy in three blocks, into which the patients were assigned in the chronological order. Results of the scientific studies: From 07/2016 to 02/2018 the participation was offered to 111 patients, 51 underwent both imaging examinations...Gynekologicko-porodnická klinika 1. LF UK a VFNDepartment of Obstetrics and Gynaecology First Faculty of Medicine and General University Hospital1. lékařská fakultaFirst Faculty of Medicin

    Cellulose-Based Biosensing Platforms

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    Cellulose empowers measurement science and technology with a simple, low-cost, and highly transformative analytical platform. This book helps the reader to understand and build an overview of the state of the art in cellulose-based (bio)sensing, particularly in terms of the design, fabrication, and advantageous analytical performance. In addition, wearable, clinical, and environmental applications of cellulose-based (bio)sensors are reported, where novel (nano)materials, architectures, signal enhancement strategies, as well as real-time connectivity and portability play a critical role

    Subsurface Characterization by Means of Geovisual Analytics

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    This Thesis is concerned with one of the major problems in subsurface characterizations emerging from ever-increasing loads of data in the last decades: What kind of technologies suit well for extracting novel, valid and useful knowledge from persistent data repositories for the characterization of subsurface regions and how can such technologies be implemented in an integrated, community-open software platform? In order to address those questions, an interactive, open-source software platform for geoscientific knowledge discovery has been developed, which enables domain experts to generate, optimize and validate prognostic models of the subsurface domain. Such a free tool has been missing in the geoscientific community so far. The extensible software platform GeoReVi (Geological Reservoir Virtualization) implements selected aspects of geovisual analytics with special attention being paid to an implementation of the knowledge discovery in databases process. With GeoReVi the human expert can model and visualize static and dynamic systems in the subsurface in a feedback cycle. The created models can be analyzed and parameterized by means of modern approaches from geostatistics and data mining. Hence, knowledge that is useful to both the assessment of subsurface potentials and to support decision-making during the utilization process of the subsurface regions can be extracted and exchanged in a formalized manner. The modular software application is composed of both integrated and centralized databases, a graphical user interface and a business logic. In order to fulfill the needs of low computing time in accordance with high computational complexity of spatial problems, the software system makes intense use of parallelism and asynchronous programming. The competitiveness of industry branches, which are aimed at utilizing the subsurface in unknown regions, such as the geothermal energy production or carbon capture and storage, are especially dependent on the quality of spatial forecasts for relevant rock and fluid properties. Thus, the focus of this work has been laid upon the implementation of algorithms, which enhance the predictability of properties in space under consideration of uncertainty. The software system was therefore evaluated in ample real-world scenarios by solving problems from scientific, educational and industrial projects. The implemented software system shows an excellent suitability to generically address spatial problems such as interpolation or stochastic simulation under consideration of numerical uncertainty. In this context, GeoReVi served as a tool for discovering new knowledge with special regard to investigating the heterogeneity of rock media on multiple scales of investigation. Among others, it could be demonstrated that the three-dimensional scalar fields of different petrophysical and geochemical properties in sandstone media may diverge significantly at small-scales. In fact, if the small-scale variability is not considered in field-scale projects, in which the sampling density is usually low, statistical correlations and thus empirical relationships might be feigned. Furthermore, it could be demonstrated that the simple kriging variance, which is used to simulate the natural variability in sequential simulations, systematically underestimates the intrinsic variability of the investigated sandstone media. If the small-scale variability can be determined by high-resolution sampling, it can be used to enhance conditional simulations at the scale of depositional environments

    Characterizing slope instability kinematics by integrating multi-sensor satellite remote sensing observations

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    Over the past few decades, the occurrence and intensity of geological hazards, such as landslides, have substantially risen due to various factors, including global climate change, seismic events, rapid urbanization and other anthropogenic activities. Landslide disasters pose a significant risk in both urban and rural areas, resulting in fatalities, infrastructure damages, and economic losses. Nevertheless, conventional ground-based monitoring techniques are often costly, time-consuming, and require considerable resources. Moreover, some landslide incidents occur in remote or hazardous locations, making ground-based observation and field investigation challenging or even impossible. Fortunately, the advancements in spaceborne remote sensing technology have led to the availability of large-scale and high-quality imagery, which can be utilized for various landslide-related applications, including identification, monitoring, analysis, and prediction. This efficient and cost-effective technology allows for remote monitoring and assessment of landslide risks and can significantly contribute to disaster management and mitigation efforts. Consequently, spaceborne remote sensing techniques have become vital for geohazard management in many countries, benefiting society by providing reliable downstream services. However, substantial effort is required to ensure that such benefits are provided. For establishing long-term data archives and reliable analyses, it is essential to maintain consistent and continued use of multi-sensor spaceborne remote sensing techniques. This will enable a more thorough understanding of the physical mechanisms responsible for slope instabilities, leading to better decision-making and development of effective mitigation strategies. Ultimately, this can reduce the impact of landslide hazards on the general public. The present dissertation contributes to this effort from the following perspectives: 1. To obtain a comprehensive understanding of spaceborne remote sensing techniques for landslide monitoring, we integrated multi-sensor methods to monitor the entire life cycle of landslide dynamics. We aimed to comprehend the landslide evolution under complex cascading events by utilizing various spaceborne remote sensing techniques, e.g., the precursory deformation before catastrophic failure, co-failure procedures, and post-failure evolution of slope instability. 2. To address the discrepancies between spaceborne optical and radar imagery, we present a methodology that models four-dimensional (4D) post-failure landslide kinematics using a decaying mathematical model. This approach enables us to represent the stress relaxation for the landslide body dynamics after failure. By employing this methodology, we can overcome the weaknesses of the individual sensor in spaceborne optical and radar imaging. 3. We assessed the effectiveness of a newly designed small dihedral corner reflector for landslide monitoring. The reflector is compatible with both ascending and descending satellite orbits, while it is also suitable for applications with both high-resolution and medium-resolution satellite imagery. Furthermore, although its echoes are not as strong as those of conventional reflectors, the cost of the newly designed reflectors is reduced, with more manageable installation and maintenance. To overcome this limitation, we propose a specific selection strategy based on a probability model to identify the reflectors in satellite images

    Tracer and Timescale Methods for Passive and Reactive Transport in Fluid Flows

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    Geophysical, environmental, and urban fluid flows (i.e., flows developing in oceans, seas, estuaries, rivers, aquifers, reservoirs, etc.) exhibit a wide range of reactive and transport processes. Therefore, identifying key phenomena, understanding their relative importance, and establishing causal relationships between them is no trivial task. Analysis of primitive variables (e.g., velocity components, pressure, temperature, concentration) is not always conducive to the most fruitful interpretations. Examining auxiliary variables introduced for diagnostic purposes is an option worth considering. In this respect, tracer and timescale methods are proving to be very effective. Such methods can help address questions such as, "where does a fluid-born dissolved or particulate substance come from and where will it go?" or, "how fast are the transport and reaction phenomena controlling the appearance and disappearance such substances?" These issues have been dealt with since the 19th century, essentially by means of ad hoc approaches. However, over the past three decades, methods resting on solid theoretical foundations have been developed, which permit the evaluation of tracer concentrations and diagnostic timescales (age, residence/exposure time, etc.) across space and time and using numerical models and field data. This book comprises research and review articles, introducing state-of-the-art diagnostic theories and their applications to domains ranging from shallow human-made reservoirs to lakes, river networks, marine domains, and subsurface flow

    Grid configuration and land use: A syntactic study of Porto Alegre (Brazil)

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    This thesis is about the configuration of the urban grid. Configuration is understood here as a perticalor manner of zirratigement which differentiates the layout of the street grid from one part of the town to another. The problem of how to describe, in objective terms, the diversity of grid configurations that compose naturally evolved urban areas is a central concern in this investigation. This thesis is also about the scrutiny of relationships between grid configuration and the distribution of land use. It is conjectured in this respect that configurational factors given by the spatial nature of the grid may affect the way in which land use is distributed in urban areas. A sample of urban areas - grid configurations and corresponding land use distributions - taken from the city of Porto Alegre (Brazil) is the object to be investigated. The simultaneity and interaction of markedly distinct grid configurations within the same city make of Porto Alegre a case where this research has fertile grounds for development. The investigation is centred on the study of the ieWS of tfio offject The urban grid will be assessed in terms of its internal laws and properties which, in a subsequent step, will be statistically compared with the socio-economic dimension of the urban phenomenon given by the distribution of land use. Notes to the reader The non-technical reader may first refer to chapter 7 which provides a summary of the findings produced out of this i nvestigation. The analytical procedure to be developed during chapters 4, 5 and 6 should be read simultaneously with the observation of the diagrams available from the back cover of this thesis

    The US Experiments Flown on the Soviet Biosatellite Cosmos 1887

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    Cosmos 1887, a biosatellite containing biological and radiation experiments from the Soviet Union, the United States and seven other countries, was launched on September 29, 1987. One Rhesus monkey's feeder stopped working two days into the flight and a decision was made to terminate the mission after 12 1/2 days. The biosatellite returned to Earth on October 12, 1987. A system malfunction, during the reentry procedure, caused the Cosmos 1887 spacecraft to land approximately 1800 miles beyond the intended landing site and delayed the start of the postflight procedures by approximately 44 hours. Further information on the conditions at landing and postflight activities is included in the Mission Operations portion of this document. U.S. and U.S.S.R. specialists jointly conducted 26 experiments on this mission, including the postflight transfer of data, hardware and biosamples to the U.S
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