Marginal Quantities Research Articles

Simulation-based sample size calculations of marginal proportional means models for recurrent events with competing risks.

In randomised controlled trials, the outcome of interest could be recurrent events, such as hospitalisations for heart failure. If mortality rates are non-negligible, both recurrent events and competing terminal events need to be addressed when formulating the estimand and statistical analysis is no longer trivial. In order to design future trials with primary recurrent event endpoints with competing risks, it is necessary to be able to perform power calculations to determine sample sizes. This paper introduces a simulation-based approach for power estimation based on a proportional means model for recurrent events and a proportional hazards model for terminal events. The simulation procedure is presented along with a discussion of what the user needs to specify to use the approach. The method is flexible and based on marginal quantities which are easy to specify. However, the method introduces a lack of a certain type of dependence. This is explored in a sensitivity analysis which suggests that the power is robust in spite of that. Data from a randomised controlled trial, LEADER, is used as the basis for generating data for a future trial. Finally, potential power gains of recurrent event methods as opposed to first event methods are discussed.

Conservation of Genomic Information in Multiple Displacement Amplified Low-Quantity Metagenomic Material from Marine Invertebrates.

Marine invertebrate microbiomes have been a rich source of bioactive compounds and interesting genomic features. In cases where the achievable amounts of metagenomic DNA are too low for direct sequencing, multiple displacement amplification (MDA) can be used for whole genome amplification. However, MDA has known limitations which can affect the quality of the resulting genomes and metagenomes. In this study, we evaluated the conservation of biosynthetic gene clusters (BGCs) and enzymes in MDA products from low numbers of prokaryotic cells (estimated 2-850). Marine invertebrate microbiomes collected from Arctic and sub-Arctic areas served as source material. The cells were separated from the host tissue, lysed, and directly subjected to MDA. The MDA products were sequenced by Illumina sequencing. Corresponding numbers of bacteria from a set of three reference strains were treated the same way. The study demonstrated that useful information on taxonomic, BGC, and enzyme diversities was obtainable from such marginal quantities of metagenomic material. Although high levels of assembly fragmentation resulted in most BGCs being incomplete, we conclude that this genome mining approach has the potential to reveal interesting BGCs and genes from hard-to-reach biological sources.

A Statistical Hypothesis Testing Strategy for Adaptively Blending Particle Filters and Ensemble Kalman Filters for Data Assimilation

Abstract Particle filters avoid parametric estimates for Bayesian posterior densities, which alleviates Gaussian assumptions in nonlinear regimes. These methods, however, are more sensitive to sampling errors than Gaussian-based techniques such as ensemble Kalman filters. A recent study by the authors introduced an iterative strategy for particle filters that match posterior moments—where iterations improve the filter’s ability to draw samples from non-Gaussian posterior densities. The iterations follow from a factorization of particle weights, providing a natural framework for combining particle filters with alternative filters to mitigate the impact of sampling errors. The current study introduces a novel approach to forming an adaptive hybrid data assimilation methodology, exploiting the theoretical strengths of nonparametric and parametric filters. At each data assimilation cycle, the iterative particle filter performs a sequence of updates while the prior sample distribution is non-Gaussian, then an ensemble Kalman filter provides the final adjustment when Gaussian distributions for marginal quantities are detected. The method employs the Shapiro–Wilk test to determine when to make the transition between filter algorithms, which has outstanding power for detecting departures from normality. Experiments using low-dimensional models demonstrate that the approach has a significant value, especially for nonhomogeneous observation networks and unknown model process errors. Moreover, hybrid factors are extended to consider marginals of more than one collocated variables using a test for multivariate normality. Findings from this study motivate the use of the proposed method for geophysical problems characterized by diverse observation networks and various dynamic instabilities, such as numerical weather prediction models. Significance Statement Data assimilation statistically processes observation errors and model forecast errors to provide optimal initial conditions for the forecast, playing a critical role in numerical weather forecasting. The ensemble Kalman filter, which has been widely adopted and developed in many operational centers, assumes Gaussianity of the prior distribution and solves a linear system of equations, leading to bias in strong nonlinear regimes. On the other hand, particle filters avoid many of those assumptions but are sensitive to sampling errors and are computationally expensive. We propose an adaptive hybrid strategy that combines their advantages and minimizes the disadvantages of the two methods. The hybrid particle filter–ensemble Kalman filter is achieved with the Shapiro–Wilk test to detect the Gaussianity of the ensemble members and determine the timing of the transition between these filter updates. Demonstrations in this study show that the proposed method is advantageous when observations are heterogeneous and when the model has an unknown bias. Furthermore, by extending the statistical hypothesis test to the test for multivariate normality, we consider marginals of more than one collocated variable. These results encourage further testing for real geophysical problems characterized by various dynamic instabilities, such as real numerical weather prediction models.

Incorporation of a nanotechnology-based product in cementitious binders for sustainable mitigation of sulphate-induced heaving of stabilised soils

Sulphate-induced heaving in soils is a common problem caused mostly by the use of calcium-based binders in the stabilisation of sulphate-bearing soils. Sulphate-induced heaving is attributed to precipitation and growth of ettringite minerals in a high alkaline environment. A sustainable means of reducing sulphate-induced heaving by the addition of an additive called “RoadCem” (RC) to soils stabilised by calcium-based cementitious products has not been studied. RoadCem (RC) is an additive that is manufactured based on nanotechnology and comprises synthetic zeolite, alkaline metals and some complex activators as some of its constituents. This research is therefore concerned with the performance of a sulphate-bearing soil stabilised by partially substituting cement (CEM I) with ground granulated blast furnace slag (GGBS) and incorporation of marginal quantities of RC. Laboratory studies including oedometer free swelling testing, unconfined compressive tests and microstructural analyses of the phases of hydration in the stabilised soils were carried out. Results indicated a reduction in heave by about 67% when 1% of RC was included in the cementitious mix with 50% of the CEM I replaced by a combination of GGBS and RC. The use of RC in the stabilised soil was even more promising than that in which only GGBS was utilised to replace half of the CEM I proportion in the stabilised soil with the result indicating almost a 30% difference in heave reduction. Results also indicated an increase in the unsoaked strength of stabilised soil with RC inclusion compared to the stabilised mix without RC. Scanning electron micrograph studies revealed almost a complete elimination of heave-causing ettringite minerals under a 28-day hydration phase of the stabilised soil when using RC.

Sourcing and Automation of Political News and Information over Social Media in the United States, 2016-2018

Social media is an important source of news and information in the United States. But during the 2016 US presidential election, social media platforms emerged as a breeding ground for influence campaigns, conspiracy, and alternative media. Anecdotally, the nature of political news and information evolved over time, but political communication researchers have yet to develop a comprehensive, grounded, internally consistent typology of the types of sources shared. Rather than chasing a definition of what is popularly known as “fake news,” we produce a grounded typology of what users actually shared and apply rigorous coding and content analysis to define the phenomenon. To understand what social media users are sharing, we analyzed large volumes of political conversations that took place on Twitter during the 2016 presidential campaign and the 2018 State of the Union address in the United States. We developed the concept of “junk news,” which refers to sources that deliberately publish misleading, deceptive, or incorrect information packaged as real news. First, we found a 1:1 ratio of junk news to professionally produced news and information shared by users during the US election in 2016, a ratio that had improved by the State of the Union address in 2018. Second, we discovered that amplifier accounts drove a consistently higher proportion of political communication during the presidential election but accounted for only marginal quantities of traffic during the State of the Union address. Finally, we found that some of the most important units of analysis for general political theory—parties, the state, and policy experts—generated only a fraction of the political communication.

Nonparametric rank based estimation of bivariate densities given censored data conditional on marginal probabilities

In this note we develop a new Kaplan-Meier product-limit type estimator for the bivariate survival function given right censored data in one or both dimensions. Our derivation is based on extending the constrained maximum likelihood density based approach that is utilized in the univariate setting as an alternative strategy to the approach originally developed by Kaplan and Meier (1958). The key feature of our bivariate survival function is that the marginal survival functions correspond exactly to the Kaplan-Meier product limit estimators. This provides a level of consistency between the joint bivariate estimator and the marginal quantities as compared to other approaches. The approach we outline in this note may be extended to higher dimensions and different censoring mechanisms using the same techniques.

Production of extremely low volatile organic compounds from biogenic emissions: Measured yields and atmospheric implications

Oxidation products of monoterpenes and isoprene have a major influence on the global secondary organic aerosol (SOA) burden and the production of atmospheric nanoparticles and cloud condensation nuclei (CCN). Here, we investigate the formation of extremely low volatility organic compounds (ELVOC) from O3 and OH radical oxidation of several monoterpenes and isoprene in a series of laboratory experiments. We show that ELVOC from all precursors are formed within the first minute after the initial attack of an oxidant. We demonstrate that under atmospherically relevant concentrations, species with an endocyclic double bond efficiently produce ELVOC from ozonolysis, whereas the yields from OH radical-initiated reactions are smaller. If the double bond is exocyclic or the compound itself is acyclic, ozonolysis produces less ELVOC and the role of the OH radical-initiated ELVOC formation is increased. Isoprene oxidation produces marginal quantities of ELVOC regardless of the oxidant. Implementing our laboratory findings into a global modeling framework shows that biogenic SOA formation in general, and ELVOC in particular, play crucial roles in atmospheric CCN production. Monoterpene oxidation products enhance atmospheric new particle formation and growth in most continental regions, thereby increasing CCN concentrations, especially at high values of cloud supersaturation. Isoprene-derived SOA tends to suppress atmospheric new particle formation, yet it assists the growth of sub-CCN-size primary particles to CCN. Taking into account compound specific monoterpene emissions has a moderate effect on the modeled global CCN budget.

Concurrent generation of binary and nonnormal continuous data through fifth-order power polynomials

ABSTRACTData collection process in most observational and experimental studies yield different types of variables, leading to the use of joint models that are capable of handling multiple data types. Evaluation of various statistical techniques that have been developed for mixed data in simulated environments requires concurrent generation of multiple variables. In this article, I present an important augmentation to a unified framework proposed in our previously published work for simultaneously generating binary and nonnormal continuous data given the marginal characteristics and correlation structure, via fifth-order power polynomials that are known to extend the area covered in the skewness-elongation plane and to provide a better approximation to the probability density function of the continuous variables. I evaluate how well the improved methodology performs in comparison to the original one, in a simulated setting with illustrations of algorithmic steps. Although the relative gains for the associational quantities are not substantial, the augmented version appears to better capture the marginal quantities that are pertinent to the higher-order moments, as indicated by very close resemblance between the specified and empirically computed quantities on average.

Welfare Measures to Assess Urban Quality of Life

The standard index of urban quality of life provides an approximated value of the quality of life, since it associates the bundles of amenities observed in urban areas with their implicit marginal prices, and not with the prices of infra-marginal units. In this paper, we adjust the standard measure to determine the monetary value of any bundle, which might substantially differ from the bundle of the marginal quantities of amenities. Our methodology relies on a welfare measure that represents the individual willingness to give up (accept) to insure (forego) a change in the current distribution of amenities across areas will take place, keeping the level of utility unchanged. We obtain a new measure, the value-adjusted quality of life index, that can be identified from parametric models of consumer preferences. We use this index to measure the quality of life in the city of Milan.

European Competition Law

The European Union(EU) is more than a common market and an economic union. Nevertheless, implementing the internal market is still one of the core goals of the EU. It aims to accomplish a highly competitive social market economy, protected against distortion of and interference with competition. The European competition law has gained increasing influence over the past years. One reason is the changed system of enforcement which gives national competition authorities and courts more competences to interpret and enforce European competition law. Another reason in the constant nominal thresholds which separate the scope of European and national competition law. Due to inflation and market concentration they are de-facto decreasing in the course of time. Furthermore, European cartel and merger control has to be observed not only by European companies but by any undertaking worldwide having small but not negligible turnover in the European Union. This has been illustrated by the take-over of the Californian computer producer AST Research by Samsung. Samsung marketed only marginal quantities in the EU and AST had a European market share of only 2.5% at that time. The companies failed to file a merger notification with the Commission. Though the Commission imposed comparatively small fines in that case, companies should be aware of higher fines in the future as the Commission might take the Samsung/AST case as precedent and might presume a greater awareness of European competition law.

Value-Driven River Management: A Murray River Case Study

This paper outlines a quasi-economic hydrological model and management paradigm geared toward public and not-for-profit regulatory bodies, with particular reference to the southern Murray-Darling Basin in southeast Australia. This value-oriented model and paradigm bridges the gap between short-range hydrological forecasting and long-range economic planning. Decision-making is assisted by a scenario-based methodology with a clear distinction between baseline and marginal quantities. The paradigm has applications to seasonal planning, commercial water trading, environmental stewardship and structural adjustment. Specific applications to the Murray-Darling Basin include (i) evaluation of options for infrastructure upgrades and licence buybacks intended to address resource over-allocation, and (ii) revival and rationalisation of hydrological exchange rates for temporary and permanent water trades, with the aim of rigorously accounting for third-party effects.

Value-driven river management: A Murray River case study

This paper outlines a quasi-economic hydrological model and management paradigm geared toward public and not-for-profit regulatory bodies, with particular reference to the southern Murray-Darling Basin in southeast Australia. This value-oriented model and paradigm bridges the gap between short-range hydrological forecasting and long-range economic planning. Decision-making is assisted by a scenario-based methodology with a clear distinction between baseline and marginal quantities. The paradigm has applications to seasonal planning, commercial water trading, environmental stewardship and structural adjustment. Specific applications to the Murray-Darling Basin include (i) evaluation of options for infrastructure upgrades and licence buybacks intended to address resource over-allocation, and (ii) revival and rationalisation of hydrological exchange rates for temporary and permanent water trades, with the aim of rigorously accounting for third-party effects.

Metabolic enzyme diversity in different human thyroid cell lines and their sensitivity to gravitational forces

Many cancer cells show unique protein expression patterns. We used proteome technology including MS, free flow isoelectric focusing and Western blotting to determine current concentrations of metabolic enzymes in healthy and malignant human thyroid cells. Three different types of human thyroid cells were investigated after they had been cultured under equal conditions. MS revealed high quantities of glycolytic enzymes and moderate quantities of citric acid cycle enzymes in malignant FTC-133 cells with abnormal LDH B-chains, high quantities of glycolytic enzymes and marginal quantities of citric acid cycle enzymes in normal HTU-5 cells, and low quantities of glycolytic enzymes and marginal quantities of citrate cycle enzymes in malignant CGTH-W1 cells with abnormal LDH A-chains. When an alteration of gene expression activity was challenged physically by removing gravity forces, the concentrations of various glycolytic enzymes were changed in normal and malignant thyroid cells. However, the changes varied among the different cell types. Different cellular alignment of the enzymes could be one reason for the cell type-specific behavior as demonstrated by histological analysis of alpha-enolase.

Implementation of marginal quantities in management of cogeneration units operating in liberal market environment

AbstractIt is far more important how the cogeneration units are operated than whether they represent the latest technology progress or not. Therefore, for the management of cogeneration units it is a key issue to find optimal operating conditions bringing in the largest income. This may be achieved by combined marginal and overall performance criteria application. To prove this statement, two cogeneration units operating in the Slovak Republic, marked as A and B, were examined. Both of them use the liberal market environment and participate in provisioning ancillary services. Marginal profit values without and with ancillary services provisioning clearly indicate the most advantageous base load value, which is in both cases in the middle of the load regulation range. As shown, together with the total profit function, they are very suitable indicators of the optimal load location and a flexible tool for the market situation evaluation. Heat delivery capability of B to customers reaches its maximum at the middle of the load regulation range, again reinforcing the optimal part load operation. Being equipped with supplementary firing, the marginal steam production of B was found to be higher than 100 % which confirms that the rules for marginal quantities values are not as strict as those for overall and specific quantities.

Possible effects of the hurricane Gudrun on the regional Swedish forest energy supply

Abstract This paper presents a snapshot speculative analysis of some possible effects of the massive windthrow in south Sweden on January 8–9, 2005. Hurricane Gudrun damaged buildings and blocked roads, making large areas inaccessible except by helicopter. Electricity and telecommunications were shambolic. Around 70 million cubic metres were windthrown, equalling a ‘normal’ Swedish annual felling––a gross value exceeding €20,000,000,000. The paper presents the subsequent restoration work that has placed a special focus on the forest sector. In south Sweden, logging work will last for a couple of years. The roundwood market will be severely strained. For individual forest owners, the economic effects of the storm are often disastrous. To ensure that forest owners will retrieve at least part of the pre-storm forest value, restoration aims at the salvaging of maximum value. Sawmills try to store the most valuable timber for years to come, decreasing the risk of painful capacity adjustments and protecting export opportunities. Forest fuel value is low compared to sawlogs and pulpwood. Thus, the forest energy sector has received little attention. Forest chippers normally contribute important marginal quantities of wood fuels, but since no logging residues will be harvested from the windthrown forests for a period of 2–3 years, they are put out of business and may disappear from the market. Heating and power plants will receive an abundance of industrial by-products in the coming 2–3 years, followed by a period of expected shortage of woody biomass for energy production. With few forest chippers left, the situation will be troublesome.

Immune Response of Broiler Chicks to DL-Methionine Supplementation at Different Ages

The study was conducted to evaluate the effect of methionine (ME) supplementation on immune response of broiler chicks during the period of 1 -7 and 29 - 36 day of age. The amino acid powder was st th th th supplemented as 1gm/L of drinking water or as 1gm/kg of feed during these early and late period of supplementation. The mean value of bursa of Fabricius, spleen and thymus weights of chicks supplemented DL-ME during the early period of age showed significant increment (P<0.05). Whereas chicks which were supplemented during the late period of the maturation of the immune system did not show significant increasing in lymphoid organ weights. Of all the blood parameters examined, the red blood cell counts and mean cell volume showed significant increment (P<0.05) from the control. Other haematological values were more than that of the normal values. The values of serum and liver total protein, albumin and globulin were highest but did not vary significantly from one another and from the control. We concluded that better immune response could be obtained with adequate supplementation of ME which have been identified to be in marginal quantities in poultry feed.

Expression of mRNAs of multidrug resistance proteins (Mrps) in cultured rat astrocytes, oligodendrocytes, microglial cells and neurones.

Multidrug resistance proteins (Mrps) are ATP-driven export pumps that mediate the export of organic anions from cells. So far only little information is available on expression and physiological functions of Mrps in brain. The expression of mRNAs of six Mrp paralogs in rat brain, as well as in rat cultures enriched for neurones, astrocytes, oligodendrocytes and microglial cells, was studied by qualitative and semiquantitative RT-PCR analysis. In adult rat brain as well as in neural cell cultures the mRNAs coding for Mrp1, Mrp3, Mrp4 and Mrp5 were detected. Semiquantitative analysis revealed that the mRNAs coding for Mrp1 and Mrp5 were more abundant in the four cell culture types than mRNAs of the other Mrps. mRNAs coding for Mrp3 and Mrp4 were found at significant levels in cultured astrocytes and microglial cells, whereas cultures of neurones and oligodendrocytes contained only marginal quantities of these mRNAs. Putative physiological functions of Mrps in brain cells are discussed.

Identification of Value-adding Strategies in the Swedish Sawn Wood Industry

Swedish sawmills are increasing their application of value-adding processes in sawn wood production. This study identified the most common value-adding combinations used by the Swedish sawmills. Data were obtained from a survey of Swedish sawmills in 1995 and from industry statistics. Nine different groupings of sawmills with regard to the level and types of value-adding technologies were identified by cluster analysis. The largest group added value only to marginal quantities of their production. Eight other groups that applied different combinations of value-adding processes were identified. Drying and planing were important elements in several strategies. Adding value to the sawn wood is not a homogeneous strategy; instead it includes several ways to focus production on different products and customer groups. Advanced value-adding processes often generated a higher unit profit margin than the production of commodity sawn wood.

Simultaneous estimation of the demand and supply of differentiated audits

This study shows how the supply and demand for auditing services is analyzed in a simultaneous equations framework. An important aspect of the analysis is the assumption that an audit is a differentiated product that is valued for its productive attributes. A hedonic (multiattribute), nonlinear fee function defines the fees that clear the market for all audit packages traded. Analysis of marginal fees and quantities of audit attributes transacted requires simultaneous estimation of a supply and demand function for each attribute. Several approaches for estimating the hedonic fee function and achieving parameter identification in the underlying structural equations are suggested.

Computation of bivariate gamma and inverted beta distribution functions

This paper considers the evaluation of the distribution functions of the bivariate gamma distribution of Wicksell and Kibble, and a bivariate inverted beta distribution. Simple expansions of the distribution functions in terms of marginal quantities and the negative binomial probabilities are derived.