Estimation for two-phase longitudinal surveys with application to the National Resources Inventory

Many longitudinal surveys can be represented as two-phase samples, where the entire set of observed units can be considered to be a first-phase sample and the second-phase samples are panels that are observed at times determined by an observation scheme. Common longitudinal schemes such as pure panel, rotating panels, and supplemented panels fit this two-phase sample description. We propose a cell-mean model with a fixed number of time points and panels where the model links the vector of second-phase panel means to the vector of time point population means. Covariance matrix estimation techniques that rely on fitting theoretical autocovariance functions to empirical covariances using nonlinear least squares are presented. A method for pooling covariance estimators across partially overlapping panels is described. The estimated generalized least squares estimator (EGLSE) is proposed for the vector of time means. Given a consistent first-phase replication variance estimator, the properties of a consistent replication estimator for the variance of the EGLSE are derived. A central limit theorem for the mean vector is given for the EGLSE under stratified fixed-rate second-phase sampling. We examine weight adjustments and imputation procedures for creating an output dataset that reflects the EGLSEs for key variables. Weight adjustment through regression estimation is proposed for a dataset containing a panel that is always observed and the replication variance estimator is extended to the regression estimator. For constructing a complete dataset, we consider imputation methods where the imputed values are chosen so that the weighted total equals the EGLSE. Results are illustrated using the National Resources Inventory, which has a supplemented panel design

A calibration experiment in a longitudinal survey with errors-in-variables

The National Resources Inventory (NRI) is a large-scale longitudinal survey conducted to assess trends and conditions of nonfederal land. A key NRI estimate is year-to-year change in acres of developed land, where developed land includes roads and urban areas. In 2003, a digital data collection procedure was implemented replacing a map overlay. Data from an NRI calibration experiment are used to estimate the relationship between data collected under the old and new protocols. A measurement error model is postulated for the relationship, where duplicate measurements are used to estimate one of the error variances. If any significant discrepancy is detected between new and old measures, some parameters that govern the algorithm under new protocol can be changed to alter the relationship. Parameters were calibrated so overall averages nearly match for the new and old protocols. Analyses on the data after initial parameter calibration suggest that the relationship is a line with an intercept of zero and a slope of one, therefore the parameters currently used are acceptable. The paper also provides models of the measurement error variances as functions of the proportion of developed land, which is essential for estimating the effect of measurement error for the whole NRI data

Permian scorpions from the Petrified Forest of Chemnitz, Germany

Background: Paleozoic scorpions (Arachnida: Scorpiones) have been widely documented from the Carboniferous Period; which hosts a remarkable assemblage of more than sixty species including both putative stem- and crown-group fossils. By contrast the succeeding Permian Period is almost completely devoid of records, which are currently restricted to a trace fossil from the early Permian of New Mexico, USA and some limb fragments from the late Permian of the Vologda Region, Russia. Results: ?Opsieobuthus tungeri sp. nov. from the Petrified Forest of Chemnitz, Germany represents the first complete body fossils of scorpions from the Permian. Explosive volcanism preserved these remarkable specimens in situ as part of the palaeosol horizon and bedrock of the Petrified Forest, immediately beneath the Zeisigwald tuff horizon. This dates to the early Permian (Sakmarian) or ca. 291 Ma. Intriguingly, the specimens were obtained from a palaeosol horizon with a compacted network of different-sized woody roots and thus have been preserved in situ in their likely life position, even within their original burrows. Differences in the structure of the comb-like pectines in the two fossils offer evidence for sexual dimorphism, and permit further inferences about the ecology and perhaps even the reproductive biology of these animals. Conclusions: As putative members of a Coal Measures genus, these fossils suggest that at least some Carboniferous scorpion lineages extended their range further into the Permian. This contributes towards a picture of scorpion evolution in which both basal and derived (orthostern) forms coexisted for quite some time; probably from the end of the Carboniferous through to at least the mid Triassic

Staff Time and Motion Assessment for Administration of Erythropoiesis-Stimulating Agents: A Two-Phase Pilot Study in Clinical Oncology Practices

BACKGROUND: Erythropoiesis-stimulating agents (ESAs) are used for the management of anaemia in patients with non-myeloid malignancies where anaemia is due to the effect of concomitant myelosuppressive chemotherapy. Assessing the impact of different ESA dosing regimens on office staff time and projected labour costs is an important component of understanding the potential for optimization of oncology practice efficiencies. OBJECTIVES: A two-phase study was conducted to evaluate staff time and labour costs directly associated with ESA administration in real-world oncology practice settings among cancer patients undergoing chemotherapy. The objective of Phase 1 was to determine the mean staff time required for the process of ESA administration in patients with anaemia due to concomitantly administered chemotherapy. The objective of Phase 2 was to quantify and compare the mean staff time and mean labour costs of ESA administered once weekly (qw) with ESA once every 3 weeks (q3w) over an entire course of chemotherapy. METHODS: Phase 1 was a prospective, cross-sectional time and motion study conducted in six private oncology practices in the US based on nine steps associated with ESA administration. Using findings from Phase 1, Phase 2 was conducted as a retrospective chart review to collect data on the number and types of visits in two private oncology practices for patients receiving a complete course of myelosuppressive chemotherapy. RESULTS: In Phase 1, the mean total time that clinic staff spent on ESA administration was 23.2 min for patient visits that included chemotherapy administration (n(chemo) = 37) and 21.5 min when only ESA was administered (n(ESAonly) = 36). In Phase 2, the mean duration of treatment was significantly longer for q3w than qw (53.84 days for qw vs. 113.38 for q3w, p < 0.0001); thus, analyses were adjusted using analysis of covariance (ANCOVA) for episode duration for between-group comparisons. Following adjustment by ANCOVA, qw darbepoetin alfa (DA) patients (n(qw) = 83) required more staff time for ESA + chemotherapy visits and ESA-only visits than q3w patients (n(q3w) = 118) over a course of chemotherapy. Overall, mean total staff time expended per chemotherapy course was greater for patients receiving qw versus q3w DA. Weekly DA dosing was associated with greater projected mean labour costs ($US38.16 vs.$US31.20 [average for 2007–2010]). CONCLUSIONS: The results from this real-world study demonstrate that oncology practices can attain staff time and labour costs savings through the use of q3w ESA. The degree of savings depends on the individual oncology practice’s staffing model and ESA administration processes, including those that allow for optimized synchronization of patient visits for ESA and chemotherapy administration. These findings indicate that additional research using standard ESA administration protocols for longer periods of time with a larger number of oncology practices and patients should be conducted to confirm these findings

Nanoscale structuring of tungsten tip yields most coherent electron point-source

This report demonstrates the most spatially-coherent electron source ever reported. A coherence angle of 14.3 +/- 0.5 degrees was measured, indicating a virtual source size of 1.7 +/-0.6 Angstrom using an extraction voltage of 89.5 V. The nanotips under study were crafted using a spatially-confined, field-assisted nitrogen etch which removes material from the periphery of the tip apex resulting in a sharp, tungsten-nitride stabilized, high-aspect ratio source. The coherence properties are deduced from holographic measurements in a low-energy electron point source microscope with a carbon nanotube bundle as sample. Using the virtual source size and emission current the brightness normalized to 100 kV is found to be 7.9x10^8 A/sr cm^2

Use of electronic medical records (EMR) for oncology outcomes research: assessing the comparability of EMR information to patient registry and health claims data

Electronic medical records (EMRs) are used increasingly for research in clinical oncology, epidemiology, and comparative effectiveness research (CER)

Towards a Conceptual Model and Reasoning Structure for Insider Threat Detection

The insider threat faced by corporations and governments today is a real and significant problem, and one that has become increasingly difficult to combat as the years have progressed. From a technology standpoint, traditional protective measures such as intrusion detection systems are largely inadequate given the nature of the ‘insider’ and their legitimate access to prized organisational data and assets. As a result, it is necessary to research and develop more sophisticated approaches for the accurate recognition, detection and response to insider threats. One way in which this may be achieved is by understanding the complete picture of why an insider may initiate an attack, and the indicative elements along the attack chain. This includes the use of behavioural and psychological observations about a potential malicious insider in addition to technological monitoring and profiling techniques. In this paper, we propose a framework for modelling the insider-threat problem that goes beyond traditional technological observations and incorporates a more complete view of insider threats, common precursors, and human actions and behaviours. We present a conceptual model for insider threat and a reasoning structure that allows an analyst to make or draw hypotheses regarding a potential insider threat based on measurable states from real-world observations

Objective effect manifestation of pectus excavatum on load-stressed pulmonary function testing: a case report

Abstract Introduction Pectus excavatum is the most common congenital deformity of the anterior chest wall that, under certain conditions, may pose functional problems due to cardiopulmonary compromise and exercise intolerance. Case presentation We present the case of an otherwise physically-adept 21-year-old Chinese sportsman with idiopathic pectus excavatum, whose symptoms manifested only on bearing a loaded body vest and backpack during physical exercise. Corroborative objective evidence was obtained via load-stressed pulmonary function testing, which demonstrated restrictive lung function. Conclusion This report highlights the possible detrimental synergism of thoracic load stress and pectus excavatum on cardiopulmonary function. Thoracic load-stressed pulmonary function testing provides objective evidence in support of such a synergistic relationship.</p

Understanding Insider Threat: A Framework for Characterising Attacks

The threat that insiders pose to businesses, institutions and governmental organisations continues to be of serious concern. Recent industry surveys and academic literature provide unequivocal evidence to support the significance of this threat and its prevalence. Despite this, however, there is still no unifying framework to fully characterise insider attacks and to facilitate an understanding of the problem, its many components and how they all fit together. In this paper, we focus on this challenge and put forward a grounded framework for understanding and reflecting on the threat that insiders pose. Specifically, we propose a novel conceptualisation that is heavily grounded in insider-threat case studies, existing literature and relevant psychological theory. The framework identifies several key elements within the problem space, concentrating not only on noteworthy events and indicators- technical and behavioural- of potential attacks, but also on attackers (e.g., the motivation behind malicious threats and the human factors related to unintentional ones), and on the range of attacks being witnessed. The real value of our framework is in its emphasis on bringing together and defining clearly the various aspects of insider threat, all based on real-world cases and pertinent literature. This can therefore act as a platform for general understanding of the threat, and also for reflection, modelling past attacks and looking for useful patterns

Efficacy and Safety of Evolocumab in Reducing Lipids and Cardiovascular Events

BACKGROUND: Evolocumab, a monoclonal antibody that inhibits proprotein convertase subtilisin-kexin type 9 (PCSK9), significantly reduced low-density lipoprotein (LDL) cholesterol levels in short-term studies. We conducted two extension studies to obtain longer-term data. METHODS: In two open-label, randomized trials, we enrolled 4465 patients who had completed 1 of 12 phase 2 or 3 studies ("parent trials") of evolocumab. Regardless of study-group assignments in the parent trials, eligible patients were randomly assigned in a 2:1 ratio to receive either evolocumab (140 mg every 2 weeks or 420 mg monthly) plus standard therapy or standard therapy alone. Patients were followed for a median of 11.1 months with assessment of lipid levels, safety, and (as a prespecified exploratory analysis) adjudicated cardiovascular events including death, myocardial infarction, unstable angina, coronary revascularization, stroke, transient ischemic attack, and heart failure. Data from the two trials were combined. RESULTS: As compared with standard therapy alone, evolocumab reduced the level of LDL cholesterol by 61%, from a median of 120 mg per deciliter to 48 mg per deciliter (P<0.001). Most adverse events occurred with similar frequency in the two groups, although neurocognitive events were reported more frequently in the evolocumab group. The risk of adverse events, including neurocognitive events, did not vary significantly according to the achieved level of LDL cholesterol. The rate of cardiovascular events at 1 year was reduced from 2.18% in the standard-therapy group to 0.95% in the evolocumab group (hazard ratio in the evolocumab group, 0.47; 95% confidence interval, 0.28 to 0.78; P=0.003). CONCLUSIONS: During approximately 1 year of therapy, the use of evolocumab plus standard therapy, as compared with standard therapy alone, significantly reduced LDL cholesterol levels and reduced the incidence of cardiovascular events in a prespecified but exploratory analysis. (Funded by Amgen; OSLER-1 and OSLER-2 ClinicalTrials.gov numbers, NCT01439880 and NCT01854918.)