1,226 research outputs found
A truncated mean-parameterised Conway-Maxwell-Poisson model for the analysis of Test match bowlers
A truncated, mean-parameterized Conway-Maxwell-Poisson model is developed to handle under- and overdispersed count data owing to individual heterogeneity. The truncated nature of the data allows for a more direct implementation of the model than is utilized in previous work without too much computational burden. The model is applied to a large dataset of Test match cricket bowlers, where the data are in the form of small counts and range in time from 1877 to the modern day, leading to the inclusion of temporal effects to account for fundamental changes to the sport and society. Rankings of sportsmen and women based on a statistical model are often handicapped by the popularity of inappropriate traditional metrics, which are found to be flawed measures in this instance. Inferences are made using a Bayesian approach by deploying a Markov Chain Monte Carlo algorithm to obtain parameter estimates and to extract the innate ability of individual players. The model offers a good fit and indicates that there is merit in a more sophisticated measure for ranking and assessing Test match bowlers
Geographic Variation in Health Care: The Role of Private Markets
health care, public sector, Medicare, insurance
Examining the impact of critical attributes on hard drive failure times: Multi-state models for left-truncated and right-censored semi-competing risks data
\ua9 2023 The Authors. Applied Stochastic Models in Business and Industry published by John Wiley & Sons Ltd. The ability to predict failures in hard disk drives (HDDs) is a major objective of HDD manufacturers since avoiding unexpected failures may prevent data loss, improve service reliability, and reduce data center downtime. Most HDDs are equipped with a threshold-based monitoring system named self-monitoring, analysis and reporting technology (SMART). The system collects several performance metrics, called SMART attributes, and detects anomalies that may indicate incipient failures. SMART works as a nascent failure detection method and does not estimate the HDDs\u27 remaining useful life. We define critical attributes and critical states for hard drives using SMART attributes and fit multi-state models to the resulting semi-competing risks data. The multi-state models provide a coherent and novel way to model the failure time of a hard drive and allow us to examine the impact of critical attributes on the failure time of a hard drive. We derive dynamic predictions of conditional survival probabilities, which are adaptive to the state of the drive. Using a dataset of HDDs equipped with SMART, we find that drives are more likely to fail after entering critical states. We evaluate the predictive accuracy of the proposed models with a case study of HDDs equipped with SMART, using the time-dependent area under the receiver operating characteristic curve (AUC) and the expected prediction error (PE). The results suggest that accounting for changes in the critical attributes improves the accuracy of dynamic predictions
A methodological review of joint modelling of multivariate time-to-event data and longitudinal outcomes
Effects of seed predators of different body size on seed mortality in Bornean logged gorest
Background The Janzen-Connell hypothesis proposes that seed and seedling enemies play a major role in maintaining high levels of tree diversity in tropical forests. However, human disturbance may alter guilds of seed predators including their body size distribution. These changes have the potential to affect seedling survival in logged forest and may alter forest composition and diversity. Methodology/Principal Findings We manipulated seed density in plots beneath con- and heterospecific adult trees within a logged forest and excluded vertebrate predators of different body sizes using cages. We show that small and large-bodied predators differed in their effect on con- and heterospecific seedling mortality. In combination small and large-bodied predators dramatically decreased both con- and heterospecific seedling survival. In contrast, when larger-bodied predators were excluded small-bodied predators reduced conspecific seed survival leaving seeds coming from the distant tree of a different species. Conclusions/Significance Our results suggest that seed survival is affected differently by vertebrate predators according to their body size. Therefore, changes in the body size structure of the seed predator community in logged forests may change patterns of seed mortality and potentially affect recruitment and community composition
Measuring the impact of research: lessons from the UK’s Research Excellence Framework 2014
Impactful academic research plays a stellar role in society, pressing to ask the question of how one measures the impact created by different areas of academic research. Measuring the societal, cultural, economic and scientific impact of research is currently the priority of the National Science Foundation, European Commission and several research funding agencies. The recently concluded United Kingdom’s national research quality exercise, the Research Excellence Framework (REF) 2014, which piloted impact assessment as part of the overall evaluation offers a lens to view how impact of research in different disciplines can be measured. Overall research quality was assessed through quality of outputs, ‘impact’ and research environment. We performed two studies using the REF 2014 as a case study. The first study on 363 Impact Case Studies (ICSs) submitted in 5 research areas (UoAs) reveals that, in general, the impact scores were constructed upon a combination of factors i.e. quantity of quartile-one (Q1) publications, quantity and value of grants/income, number of researchers stated in the ICSs, spin-offs created, discoveries/patents and presentation of esteem data, informing researchers/ academics of the factors to consider in order to achieve a better impact score in research impact assessments. However, there were differences among disciplines in terms of the role played by the factors in achieving their overall scores for the ICSs. The outcome of this study is thus a set of impact indicators, and their relationship with the overall score of impact of research in different disciplines as determined in REF2014, which would in the first instance provide some answers to impact measures that would be useful for researchers in different disciplines. The second study extracts the general themes of impact reported by universities by performing a word frequency analysis in all the ICSs submitted in the five chosen research areas, which were substantially varied owing to their fields
Complete atrial-specific knockout of sodium-calcium exchange eliminates sinoatrial node pacemaker activity.
The origin of sinoatrial node (SAN) pacemaker activity in the heart is controversial. The leading candidates are diastolic depolarization by "funny" current (If) through HCN4 channels (the "Membrane Clock" hypothesis), depolarization by cardiac Na-Ca exchange (NCX1) in response to intracellular Ca cycling (the "Calcium Clock" hypothesis), and a combination of the two ("Coupled Clock"). To address this controversy, we used Cre/loxP technology to generate atrial-specific NCX1 KO mice. NCX1 protein was undetectable in KO atrial tissue, including the SAN. Surface ECG and intracardiac electrograms showed no atrial depolarization and a slow junctional escape rhythm in KO that responded appropriately to β-adrenergic and muscarinic stimulation. Although KO atria were quiescent they could be stimulated by external pacing suggesting that electrical coupling between cells remained intact. Despite normal electrophysiological properties of If in isolated patch clamped KO SAN cells, pacemaker activity was absent. Recurring Ca sparks were present in all KO SAN cells, suggesting that Ca cycling persists but is uncoupled from the sarcolemma. We conclude that NCX1 is required for normal pacemaker activity in murine SAN
An Economic Evaluation of the War on Cancer
For decades, the US public and private sectors have committed substantial resources towards cancer research, but the societal payoff has not been well-understood. We quantify the value of recent gains in cancer survival, and analyze the distribution of value among various stakeholders. Between 1988 and 2000, life expectancy for cancer patients increased by roughly four years, and the average willingness-to-pay for these survival gains was roughly 1.9 trillion of additional social value, implying that the average life-year was worth approximately $82,000 to its recipient. Health care providers and pharmaceutical companies appropriated 5-19% of this total, with the rest accruing to patients. The share of value flowing to patients has been rising over time. These calculations suggest that from the patient's point of view, the rate of return to R&D investments against cancer has been substantial.
MAES Service Case: Wetland ecosystem condition mapping (v.1.0)
SWOS Technical publicationThe MAES working group is preparing the workshop on “ecosystem condition mapping” to streamline the efforts done so far with regards to the mapping and assessment of the condition of Europe’s ecosystems. The MAES WG has requested directly to SWOS partners a specific document to support the mapping and assessing wetland ecosystem condition for this workshop. This document shall highlight the different elements to take into account for the mapping and assessment of wetland ecosystems with the aim of supporting Member States and the European Commission in their efforts to better describe the situation of wetland ecosystems in Europe.
This document represents the major output of the MAES Service case that shall show how SWOS outputs are useful to support the MAES WG with regards to wetland ecosystem mapping and assessment
Diversity II water quality parameters from ENVISAT (2002–2012): a new global information source for lakes
The use of ground sampled water quality information for global studies is
limited due to practical and financial constraints. Remote sensing is a
valuable means to overcome such limitations and to provide synoptic views of
ambient water quality at appropriate spatio-temporal scales. In past years
several large data processing efforts were initiated to provide corresponding
data sources. The Diversity II water quality dataset consists of several
monthly, yearly and 9-year averaged water quality parameters for 340 lakes
worldwide and is based on data from the full ENVISAT MERIS operation period
(2002–2012). Existing retrieval methods and datasets were selected after an
extensive algorithm intercomparison exercise. Chlorophyll-a, total
suspended matter, turbidity, coloured dissolved organic matter, lake surface
water temperature, cyanobacteria and floating vegetation maps, as well as
several auxiliary data layers, provide a generically specified database that
can be used for assessing a variety of locally relevant ecosystem properties
and environmental problems. For validation and accuracy assessment, we
provide matchup comparisons for 24 lakes and a group of reservoirs
representing a wide range of bio-optical conditions. Matchup comparisons for
chlorophyll-a concentrations indicate mean absolute errors and bias in the
order of median concentrations for individual lakes, while total suspended
matter and turbidity retrieval achieve significantly better performance
metrics across several lake-specific datasets. We demonstrate the use of the
products by illustrating and discussing remotely sensed evidence of
lake-specific processes and prominent regime shifts documented in the
literature. The Diversity II data are available from
https://doi.pangaea.de/10.1594/PANGAEA.871462, and Python scripts for
their analysis and visualization are provided at
https://github.com/odermatt/diversity/.</p
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