Travel cost and time measurement in travel cost models.

Cost; Measurement; Model; Models; Time; Working;

Performance of an Iterative Two-stage Bayesian Technique for Population Pharmacokinetic Analysis of Rich Data Sets

Purpose. To test the suitability of an Iterative Two-Stage Bayesian (ITSB) technique for population pharmacokinetic analysis of rich data sets, and to compare ITSB with Standard Two-Stage (STS) analysis and nonlinear Mixed Effect Modeling (MEM). Materials and Methods. Data from a clinical study with rapacuronium and data generated by Monte Carlo simulation were analyzed by an ITSB technique described in literature, with some modifications, by STS, and by MEM (using NONMEM). The results were evaluated by comparing the mean error (accuracy) and root mean squared error (precision) of the estimated parameter values, their interindividual standard deviation, correlation coefficients, and residual standard deviation. In addition, the influence of initial estimates, number of subjects, number of measurements, and level of residual error on the performance of ITSB were investigated. Results. ITSB yielded best results, and provided precise and virtually unbiased estimates of the population parameter means, interindividual variability, and residual standard deviation. The accuracy and precision of STS was poor, whereas ITSB performed better than MEM. Conclusions. ITSB is a suitable technique for population pharmacokinetic analysis of rich data sets, and in the presented data set it is superior to STS and MEM

Population pharmacodynamic modeling using the sigmoid E-max model : influence of inter-individual variability on the steepness of the concentration-effect relationship : a simulation study

The relationship between the concentration of a drug and its pharmacological effect is often described by empirical mathematical models. We investigated the relationship between the steepness of the concentration-effect relationship and inter-individual variability (IIV) of the parameters of the sigmoid E-max model, using the similarity between the sigmoid E-max model and the cumulative log-normal distribution. In addition, it is investigated whether IIV in the model parameters can be estimated accurately by population modeling. Multiple data sets, consisting of 40 individuals with 4 binary observations in each individual, were simulated with varying values for the model parameters and their IIV. The data sets were analyzed using Excel Solver and NONMEM. An empirical equation (Eq. (11)) was derived describing the steepness of the population-predicted concentration-effect profile (gamma*) as a function of gamma and IIV in C50 and gamma, and was validated for both binary and continuous data. The tested study design is not suited to estimate the IIV in C50 and gamma with reasonable precision. Using a naive pooling procedure, the population estimates gamma* are significantly lower than the value of gamma used for simulation. The steepness of the population-predicted concentration-effect relationship (gamma*) is less than that of the individuals (gamma). Using gamma*, the population-predicted drug effect represents the drug effect, for binary data the probability of drug effect, at a given concentration for an arbitrary individual

Wisconsin Farmers Take the 2-Pass Challenge Against Weeds

Single pass herbicide programs have become the standard for most Wisconsin corn producers. The apparent time and cost savings in controlling weeds with a single pre or post-emergence herbicide application is the driving force behind this trend. While there are situations where a single pass program will work, it has weaknesses that can result in inconsistent performance

How large is the gap between present and efficient transport prices in Europe?

In this paper we analyse the gap between present transport prices and efficient transport prices. Efficient transport prices are those prices that maximise economic welfare, including external costs (congestion, air pollution, accidents). The methodology is applied to six urban and interregional case studies using one common optimal pricing model. The case studies cover passenger as well as freight transport and cover all modes. We find that prices need to be raised most for peak urban passenger car transport and to a lesser extent for interregional road transport. Optimal pricing results for public transport are more mixed. We show that current external costs on congested roads are a bad guide for optimal taxes and tolls: the optimal toll that takes into account the reaction of demand is often less than one third of the present marginal external cost.transport pricing; external costs; social costs; congestion pricing

Viability, abortion and extreme prematurity:a critique

This article examines the ethical validity of using viability as the cutoff point for abortion in the Netherlands, in view of potential changes to the Dutch perinatal care guideline. According to the Dutch Penal Code, abortion is permitted until viability: the point at which a fetus can survive outside the womb with technological assistance. Since the law was enacted in 1984, viability has been set at 24 weeks gestational age. Currently, in the Netherlands, the treatment limit for extreme prematurity is also set at 24 weeks. The potential revision of the guideline could lower this threshold. Such a change could have implications for abortion in the Netherlands. We critically evaluate the use of viability within the Dutch context and offer recommendations for modifying the legal framework concerning abortion. We conclude that relying on any interpretation of viability is morally problematic for abortion regulation, as it is too indeterminate a concept to establish a threshold in a morally relevant way.</p

Viability, abortion and extreme prematurity:a critique

This article examines the ethical validity of using viability as the cutoff point for abortion in the Netherlands, in view of potential changes to the Dutch perinatal care guideline. According to the Dutch Penal Code, abortion is permitted until viability: the point at which a fetus can survive outside the womb with technological assistance. Since the law was enacted in 1984, viability has been set at 24 weeks gestational age. Currently, in the Netherlands, the treatment limit for extreme prematurity is also set at 24 weeks. The potential revision of the guideline could lower this threshold. Such a change could have implications for abortion in the Netherlands. We critically evaluate the use of viability within the Dutch context and offer recommendations for modifying the legal framework concerning abortion. We conclude that relying on any interpretation of viability is morally problematic for abortion regulation, as it is too indeterminate a concept to establish a threshold in a morally relevant way.</p

Viability, abortion and extreme prematurity:a critique

This article examines the ethical validity of using viability as the cutoff point for abortion in the Netherlands, in view of potential changes to the Dutch perinatal care guideline. According to the Dutch Penal Code, abortion is permitted until viability: the point at which a fetus can survive outside the womb with technological assistance. Since the law was enacted in 1984, viability has been set at 24 weeks gestational age. Currently, in the Netherlands, the treatment limit for extreme prematurity is also set at 24 weeks. The potential revision of the guideline could lower this threshold. Such a change could have implications for abortion in the Netherlands. We critically evaluate the use of viability within the Dutch context and offer recommendations for modifying the legal framework concerning abortion. We conclude that relying on any interpretation of viability is morally problematic for abortion regulation, as it is too indeterminate a concept to establish a threshold in a morally relevant way.</p

Viability, abortion and extreme prematurity:a critique

This article examines the ethical validity of using viability as the cutoff point for abortion in the Netherlands, in view of potential changes to the Dutch perinatal care guideline. According to the Dutch Penal Code, abortion is permitted until viability: the point at which a fetus can survive outside the womb with technological assistance. Since the law was enacted in 1984, viability has been set at 24 weeks gestational age. Currently, in the Netherlands, the treatment limit for extreme prematurity is also set at 24 weeks. The potential revision of the guideline could lower this threshold. Such a change could have implications for abortion in the Netherlands. We critically evaluate the use of viability within the Dutch context and offer recommendations for modifying the legal framework concerning abortion. We conclude that relying on any interpretation of viability is morally problematic for abortion regulation, as it is too indeterminate a concept to establish a threshold in a morally relevant way.</p