434 research outputs found
A spectrum of physics-informed Gaussian processes for regression in engineering
Despite the growing availability of sensing and data in general, we remain
unable to fully characterise many in-service engineering systems and structures
from a purely data-driven approach. The vast data and resources available to
capture human activity are unmatched in our engineered world, and, even in
cases where data could be referred to as ``big,'' they will rarely hold
information across operational windows or life spans. This paper pursues the
combination of machine learning technology and physics-based reasoning to
enhance our ability to make predictive models with limited data. By explicitly
linking the physics-based view of stochastic processes with a data-based
regression approach, a spectrum of possible Gaussian process models are
introduced that enable the incorporation of different levels of expert
knowledge of a system. Examples illustrate how these approaches can
significantly reduce reliance on data collection whilst also increasing the
interpretability of the model, another important consideration in this context
Asterixis.
Adams and Foley described asterixis in the 1940s in patients with hepatic encephalopathy, but it has since been associated with a wide range of potential causes, both in neurology and general medicine. Here, we review the history, characteristics and clinical significance of this important clinical sign
Across-ecoregion analysis suggests a hierarchy of ecological filters that regulate recruitment of a globally invasive fish
Aim -- Even successful invaders are abundant only in a fraction of locales they inhabit. One of the main challenges in invasion ecology is explaining processes that drive these patterns. We investigated recruitment of a globally invasive fish, common carp (Cyprinus carpio), across three ecoregions to determine the role of environmental characteristics, predatory communities and propagule pressure on the invasion process at coarse and fine spatial scales.
Location -- Lakes across Northern Forest, Temperate Forest and Great Plains ecoregions of North America.
Methods -- We used data from 567 lakes to model presence or absence of carp recruitment using environmental conditions (lake clarity, area, maximum depth), native predatory fishes (micropredators, mesopredators, large predators) and propagule pressure (abundance of adult carp). We formed a set of alternative models and evaluated their support using an information theoretic approach. Once most supported models were identified, we used classification tree to determine how variables included in these models interacted to affect carp recruitment. Finally, we conducted a field experiment to test the predictions of the classification tree analysis.
Results -- Carp recruitment was strongly regulated by processes associated with water clarity, which appeared to function as a broad-scale ecological filter. Carp were unlikely to recruit in clear, oligotrophic lakes (Secchi depth \u3e 2 m) despite the presence of adults in many such systems. Recruitment was more likely to occur in regions with turbid lakes, but abundant micropredators could inhibit it there.
Main conclusions -- Carp recruitment and invasions across large geographic areas are attributable to a two-layer ecological filter with lake clarity/productivity acting as a coarse-scale filter and micropredators acting as a fine-scale filter. This two-layer filter might explain the complex patterns of carp invasions among and within different ecoregions. Ecological filters may also explain the success of other aquatic invaders that show similarly patchy spatial distribution patterns
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Selecting a database management system for agricultural record keeping
Many agricultural producers are using computerized database management systems to maintain and analyze their records. Very powerful database management systems now available for desktop computers are used in a wide variety of agricultural applications. Machinery, crop, livestock, and payroll records are all commonly maintained with database management systems.
The success (or failure!) of your computerized agricultural record-keeping activities may depend in part on the database management system you use to keep your records. Choosing the system most appropriate for your needs can be quite a challenge, given the number of programs currently on the market.
If you're not familiar with database management systems, you should read WREP 107, Introduction to Database Management Systemsfor Agricultural Record Keeping. It explains the basic terms and concepts associated with using a database management system. We assume you have mastered this introductory material—and are now ready to select a system.
This publication will present several hardware and software factors to consider in selecting a database management system for your agricultural record-keeping needs. After examining each of these factors, use the checklist (page 7) to evaluate and select a database management system.Published August 1988. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalo
Recommendations for treatment strategies in people with epilepsy during times of shortage of antiseizure medications
In times of severe antiseizure medication (ASM) shortage due to emergency situations (e.g., disasters, conflicts, sudden disruption to international supply chains), management of people with epilepsy with available ASMs can be difficult. A group of experts was brought together by the International League Against Epilepsy (ILAE) to formulate recommendations for such circumstances. Every effort was made to base these recommendations on direct published literature or extrapolations from basic information available about ASMs. Actual published literature in this area is, however, limited, and at times, assumptions were made by the experts to generate these recommendations. During times of shortage of ASMs, switching between different ASMs (e.g., oxcarbazepine and carbamazepine) can occasionally be considered as a mitigation procedure. However, for many ASMs, the option of an overnight switch to another drug does not exist. Switching from brand to generic or between generic products has often been shown to be safe, if required. Finally, when supplies of benzodiazepines or equipment to administer medications intravenously are not available, rectal administration of some ASMs may be an emergency alternative route for treating serial seizures and status epilepticus. Decision-making with regard to treatment and possible options should be driven by what is best for the patient
A sampling-based approach for information-theoretic inspection management
A partially supervised approach to Structural Health Monitoring is proposed, to manage the cost associated with expert inspections and maximize the value of monitoring regimes. Unlike conventional data-driven procedures, the monitoring classifier is learnt online while making predictions—negating the requirement for complete data before a system is in operation (which are rarely available). Most critically, periodic inspections are replaced (or enhanced) by an automatic inspection regime, which only queries measurements that appear informative to the evolving model of the damage-sensitive features. The result is a partially supervised Dirichlet process clustering that manages expert inspections online given incremental data. The method is verified on a simulated example and demonstrated on in situ bridge monitoring data
Fixed-bearing Medial Unicompartmental Knee Arthroplasty Restores Neither the Medial Pivoting Behavior Nor the Ligament Forces of the Intact Knee in Passive Flexion
Medial unicompartmental knee arthroplasty (UKA) is an accepted treatment for isolated medial osteoarthritis. However, using an improper thickness for the tibial component may contribute to early failure of the prosthesis or disease progression in the unreplaced lateral compartment. Little is known of the effect of insert thickness on both knee kinematics and ligament forces. Therefore, a computational model of the tibiofemoral joint was used to determine how non-conforming, fixed bearing medial UKA affects tibiofemoral kinematics and tension in the medial collateral ligament (MCL) and the anterior cruciate ligament (ACL) during passive knee flexion. Fixed bearing medial UKA could not maintain the medial pivoting that occurred in the intact knee from 0° to 30° of passive flexion. Abnormal anterior-posterior (AP) translations of the femoral condyles relative to the tibia delayed coupled internal tibial rotation, which occurred in the intact knee from 0° to 30° flexion, but occurred from 30° to 90° flexion following UKA. Increasing or decreasing tibial insert thickness following medial UKA also failed to restore the medial pivoting behavior of the intact knee despite modulating MCL and ACL forces. Reduced AP constraint in non-conforming medial UKA relative to the intact knee leads to abnormal condylar translations regardless of insert thickness even with intact cruciate and collateral ligaments. This finding suggests that the conformity of the medial compartment as driven by the medial meniscus and articular morphology plays an important role in controlling AP condylar translations in the intact tibiofemoral joint during passive flexion
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Enterprise cost study for marion blackberries : establishment years, every year production, and alternate year production in the Mid-Willamette Valley
Published February 1987. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalo
Ultrasonography in surveillance for hepatocellular carcinoma in patients with non-alcoholic fatty liver disease
International guidelines recommend six monthly ultrasounds as the primary surveillance tool for patients at risk of hepatocellular carcinoma (HCC). The dominant driver of liver disease in HCC surveillance populations is shifting, particularly in Europe and the United States, from chronic viral hepatitis (B or C), towards non-alcoholic fatty liver disease (NAFLD). Today, the population requiring HCC surveillance is also characterised by a high prevalence of overweight/obesity. These patient characteristics significantly impair ultrasound quality which can impede the detection of early HCC lesions. This diagnostic limitation has significant implications considering that eligibility for curative treatment depends upon the stage at which the cancer is detected. In this narrative review, we provide a comprehensive overview of the published evidence and national/international guidelines regarding ultrasound surveillance for HCC in people with NAFLD. We examine ultrasound sensitivity in this cohort for the detection of all stage and early HCC, the impact of steatosis and abdominal obesity on ultrasound performance, evidence for the addition of serum alpha-fetoprotein measurement, optimal timing of surveillance, emerging modalities for risk stratification and screening, and outline the challenges of case finding and surveillance eligibility criteria in this patient cohort. Finally, amalgamating all available evidence, we propose a pragmatic surveillance pathway for patients with NAFLD.</jats:p
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