CE Model Research Articles

Preparation of the Drager Fabius CE and Drager Zeus anaesthetic machines for patients susceptible to malignant hyperthermia

Malignant hyperthermia may follow exposure to trace quantities of inhalational anaesthetics. In susceptible patients, the complete avoidance of these triggers is advised when possible; however, failing this, it is essential to washout or purge the anaesthesia machine of residual inhalational anaesthetics. This study examined the washout profile of sevoflurane from the Drager Fabius CE and the Drager Zeus machines. The washout profile of sevoflurane was measured from the Fabius CE and Zeus anaesthesia machines following a standard period of exposure. The disposable tubing, CO2 absorber and other components of each machine were then replaced to examine their impact on the retention of sevoflurane. The effect of autoclaving the ventilator diaphragm and non-disposable ventilator tube or substituting for a new diaphragm and ventilation tube were examined in later parts of this study. University teaching hospital. Time taken to reach 5 parts per million of sevoflurane when machines underwent standard washout with fresh gas flush. The concentration of sevoflurane reached 5 parts per million in the Fabius CE machines after an mean (SD) of 140 min (46) at a fresh gas flow (FGF) of 10 l min(-1). The time taken for sevoflurane to reach 5 parts per million was significantly reduced when the ventilator diaphragm and non-disposable tube were replaced with either new or autoclaved components [14 or 22 min, respectively (P = 0.017, P = 0.031)]. The concentration of sevoflurane reached 5 parts per million in the Zeus machines after an mean (SD) of 85 min (6) at a fresh gas flow of 10 l min(-1). When the fresh gas flow was increased to 18 l min(-1) (the maximum allowable), the time to reach 5 parts per million was reduced to 16 min. When preparing the Fabius CE for the malignant hyperthermia susceptible patient, remove the vaporiser, replace the disposable tubing, the reservoir bag and the CO2 absorber. Replace the ventilator diaphragm and non-disposable ventilator tube with new or autoclaved components and flush the machine at 10 l min(-1) for at least 36 min. When preparing the Zeus, remove the vaporiser, replace the disposable tubing, the reservoir bag and CO2 absorber and flush at a fresh gas flow of 10 l min(-1) for at least 90 min. In both the Fabius and Zeus, continue at a fresh gas flow of 10 l min(-1) for the duration of the operation.

Multiple Model Predictive Control of Component Content in Rare Earth Extraction Process

Aiming at the complicated characteristic of rare earth extraction process and combining the material balan- ce model, a multiple models modeling and control method is proposed. Based on the data collected in an industrial field, an improved subtractive clustering algorithm is employed to obtain steady operation points for the process; the recuresi- ve least squares algorithm is adopted to identify submodel parameters and establish multiple linear models. According to the model switching index, an online optimal predictive model is obtained. And the efficiency of the model is verified by taking a certain rare earth company extraction as an ex- ample. In the end, generalized predictive controller of the corresponding sub-model is designed, so that component content is controlled in real time and accurately. Simulation results show the effectiveness of the method above.

PIN47 Cost-Effectiveness of Telbivudine in First Line Treatment of HBEAG-Negative Patients with Chronic Hepatitis B (CHB) in the Turkish Healthcare Setting

The aim of this study is to analyze the cost-effectiveness over 6-year duration of first line telbivudine and lamivudine treatment in HBeAg-negative CHB patients with low viral load at baseline in line with the Turkish reimbursement guideline for oral CHB therapies. Using a decision analytical model, cost-effectiveness of telbivudine was evaluated versus lamivudine in first-line use for HBeAg-negative patients with baseline serum HBV DNA levels <7 log10 copies/mL in Turkish healthcare setting from national payer's perspective in accordance with the local reimbursement guideline for oral CHB treatments based on roadmap concept. Primary measure of effectiveness was undetectable HBV DNA level by polymerase chain reaction (PCR) assay at model duration, while costs included only cost of oral CHB drugs incurred by the Payer. Probabilities of PCR negativity and resistance rates used in the model are derived from telbivudine's head-to-head study vs lamivudine subgroup analyses outcomes for week 24 and 104; and from respective pivotal clinical studies for second line therapies. In the CE model, total oral CHB treatment cost per negative patient treated with lamivudine and telbivudine arm over 6 years was estimated to be 9141€ and 7980€ respectively. Percentage of patients remaining on lamivudine at model duration was 29%, while 67% on telbivudine. The average cost-effectiveness ratio, cost per successfully treated patient at year 6, was calculated as 10,754€ for the lamivudine arm and 8,750€ for the telbivudine arm (difference is 2,004€) and the incremental cost-effectiveness ratio was -18,726€. First line CHB treatment with telbivudine in negative patients has been demonstrated as a dominant cost-effective option than lamivudine in the Turkish health care setting. Although telbivudine has higher reimbursement price, it has been offset by superior efficacy compared to lamivudine in HBeAg-negative patients with baseline serum HBV DNA levels <7 log10 copies/mL and less need for more costly second line treatments.

Two-Temperature Two-Dimensional Non Chemical Equilibrium Modeling of Ar–CO2–H2 Induction Thermal Plasmas at Atmospheric Pressure

Here the authors developed a two-dimensional two-temperature chemical non-equilibrium (2T-NCE) model of Ar–CO2–H2 inductively coupled thermal plasmas (ICTP) around atmospheric pressure (760 torr). Assuming 22 different particles in this model and by solving mass conservation equations for each particle, considering diffusion, convection and net production terms resulting from 198 chemical reactions, chemical non-equilibrium effects were taken into account. Species density of each particle or simply particle composition was also derived from the mass conservation equation of each one taking the non chemical equilibrium effect into account. Transport and thermodynamic properties of Ar–CO2–H2 thermal plasmas were self-consistently calculated using the first order approximation of the Chapman–Enskog method at each iteration point implementing the local particle composition and temperature. Calculations at reduced pressure (500 and 300 torr) were also done to investigate the effect of pressure on non-equilibrium condition. Results obtained by the present model were compared with results from one temperature chemical equilibrium (1T-CE) model, one-temperature chemically non equilibrium (1T-NCE) model and finally with 2T-NCE model of Ar–N2–H2 plasmas. Investigation shows that consideration of non-chemical equilibrium causes the plasma volume radially wider than CE model due to particle diffusion. At low pressure with same input power, presence of diffusion is relatively stronger than at high pressure. Comparison of present reactive model with non-reactive Ar–N2–H2 plasmas shows that maximum temperature reaches higher in reactive C–H–O molecular system than non-reactive plasmas due to extra contribution of reaction heat.

Mind the (Approximation) Gap: A Robustness Analysis

This note continues the discussion of the results reported by Ricardo Caballero and Eduardo Engel (1993), hereafter CE, and Ricardo Caballero, Eduardo Engel, and John Haltiwanger (1997), hereafter CEH, by responding to the results reported in Christian Bayer (2008). Russell Cooper and Jonathan Willis (2004), hereafter CW, find that the aggregate nonlinearities reported in CE and CEH may be the consequence of mismeasurement of the employment gap rather than nonlinearities in plant-level adjustment. Bayer reassesses this finding in the context of the CE model in the case where static employment gaps are observed and concludes that the CW result is not robust to alternative shock processes. We concur with Bayer's assessment that the nonlinearity finding is sensitive to the aggregate profitability shock process. We argue, however, that Bayer's finding does not imply that the mismeasurement problem goes away. Instead, the nonlinearity created by mismeasurement is directly related to the level of the aggregate shock. Once the empirical specification properly incorporates the aggregate shock, the nonlinearity test is robust to alternative shock processes and confirms the results in CW. More importantly, we demonstrate that the CW findings are robust to alternative shock processes for the natural case of unobserved gaps as examined by CE and CEH.

Modelling the kinetics of hepatitis C virus RNA decline over 4 weeks of treatment with pegylated interferon α‐2b

Viral kinetic models for hepatitis C virus (HCV) have generally assumed that the effectiveness of therapy in blocking virion production, epsilon, is constant. However, with pegylated interferon alpha-2b (PEG-IFN) given weekly, there are significant changes in drug concentration between doses that may lead to changes in drug effectiveness and viral rebounds towards the end of the dosing interval. Here we investigate the effects of using a model that assumes a constant effectiveness for studies involving PEG-IFN. We simulated PEG-IFN treatment in a population of 294 computer simulated 'patients', each characterized by a different set of pharmacokinetic and pharmacodynamic parameters. We then sampled the simulated treatment data over 4 weeks with a schedule similar to that used in viral kinetic studies, and fitted a viral kinetic model assuming constant drug effectiveness, the CE model, to that data. Although the CE model was able to fit to the data well in most cases, the parameter estimates obtained scattered widely both above and below the true values. Thus, this model is less useful to analyse HCV RNA data during therapy with PEG-IFN than with standard IFN given daily. With PEG-IFN accurate estimation of viral dynamic parameters necessitates concomitant measurements of serum viral load and drug concentration.

Muscle Dissatisfaction and Muscle-Enhancing Substance Use: A Population-Based Twin Study in Young Adult Men

AbstractIn the population-based FinnTwin16 study, proportions of genetic and environmental factors contributing to muscle dissatisfaction and muscle-enhancing substance use were assessed in 319 pairs of twin brothers: 141 monozygotic (MZ) and 178 dizygotic (DZ) pairs. In addition there were 86 twin individuals from pairs in which only one co-twin responded. Of all respondents, 30% experienced high muscle dissatisfaction. The corresponding proportion of muscle-enhancing substance use was 10%. The subjects were similar in age (23.8 years, 95% confidence interval [CI] 23.76–23.84), body mass index (23.7, 95% CI 23.5–23.9), and waist circumference (84.5 cm, 95% CI 83.7–85.2), independent of their muscle dissatisfaction or muscle-enhancing substance use status and independent of their zygosity. The MZ polychoric correlation for muscle dissatisfaction was .39 (95% CI .17–.58) and .27 for DZ pairs (95% CI .07–.46). The MZ tetrachoric correlation for muscle-enhancing substance use was .65 (95% CI .28–.87) and .56 for DZ pairs (95% CI .26–.78). The AE model, where additive genetic factors (A) accounted for 42% (95% CI .23–.59) and unique environmental factors (E) 58% (95% CI .41–.77) of the liability, provided the best fit for muscle dissatisfaction. The CE model, where common environmental factors (C) accounted for 60% (95% CI .37–.77) and unique environmental factors (E) 40% (95% CI .23–.63) of the liability, provided the best fit for muscle-enhancing substance use. Both genetic and unique (nonfamilial) environmental factors are involved in muscle dissatisfaction in the population. Nongenetic factors (both familial and non-familial) appear to best explain the use of muscle-enhancing substances.

Muscle Dissatisfaction and Muscle-Enhancing Substance Use: A Population-Based Twin Study in Young Adult Men

In the population-based Finn Twin 16 study, proportions of genetic and environmental factors contributing to muscle dissatisfaction and muscle-enhancing substance use were assessed in 319 pairs of twin brothers: 141 monozygotic (MZ) and 178 dizygotic (DZ) pairs. In addition there were 86 twin individuals from pairs in which only one co-twin responded. Of all respondents, 30% experienced high muscle dissatisfaction. The corresponding proportion of muscle-enhancing substance use was 10%. The subjects were similar in age (23.8 years, 95% confidence interval [CI] 23.76-23.84), body mass index (23.7, 95% CI 23.5-23.9), and waist circumference (84.5 cm, 95% CI 83.7-85.2), independent of their muscle dissatisfaction or muscle-enhancing substance use status and independent of their zygosity. The MZ polychoric correlation for muscle dissatisfaction was .39 (95% CI .17-.58) and .27 for DZ pairs (95% CI .07-.46). The MZ tetrachoric correlation for muscle-enhancing substance use was .65 (95% CI .28-.87) and .56 for DZ pairs (95% CI .26-.78). The AE model, where additive genetic factors (A) accounted for 42% (95% CI .23-.59) and unique environmental factors (E) 58% (95% CI .41-.77) of the liability, provided the best fit for muscle dissatisfaction. The CE model, where common environmental factors (C) accounted for 60% (95% CI .37-.77) and unique environmental factors (E) 40% (95% CI .23-.63) of the liability, provided the best fit for muscle-enhancing substance use. Both genetic and unique (nonfamilial) environmental factors are involved in muscle dissatisfaction in the population. Nongenetic factors (both familial and nonfamilial) appear to best explain the use of muscle-enhancing substances.

Genetic and Environmental Influences on Age at Sexual Initiation in the Colorado Adoption Project

Whereas the majority of research on adolescent sexual initiation has focused solely on environmental factors, the present study used behavioral genetic analyses to investigate the relative contributions of genetic and environmental influences. Structural equation models were fitted to data from adoptive and non-adoptive sibling pairs (231 biologically related pairs and 169 unrelated pairs) from the Colorado Adoption Project. Information from censored individuals who had not yet experienced sexual initiation was maximized by adapting the twin survival analysis method of Pickles et al. (Behav Genet 24(5):457-468, 1994) to accommodate adoptive and non-adoptive siblings. Point estimates of variance components from an ACE model, including additive genetic (A), shared environmental (C), and non-shared environmental (E) influences were 28%, 24%, and 48%, respectively. Despite the lower point estimate for shared environmental effects than additive genetic effects, a CE model provided the best fit to the data. However, because adoptive siblings provide a direct estimate of shared environmental influences there is greater power to detect shared environmental effects in adoption designs. Evidence for genetic influences from our data were somewhat lower than those obtained in previous twin studies, possibly reflecting a return to more socially conservative sexual attitudes, changing sexual behaviors, or ambiguities in the wording of questions commonly used in research on adolescent sexuality.

Likelihood Ratio Tests in Behavioral Genetics: Problems and Solutions

The likelihood ratio test of nested models for family data plays an important role in the assessment of genetic and environmental influences on the variation in traits. The test is routinely based on the assumption that the test statistic follows a chi-square distribution under the null, with the number of restricted parameters as degrees of freedom. However, tests of variance components constrained to be non-negative correspond to tests of parameters on the boundary of the parameter space. In this situation the standard test procedure provides too large p-values and the use of the Akaike Information Criterion (AIC) or the Bayesian Information Criterion (BIC) for model selection is problematic. Focusing on the classical ACE twin model for univariate traits, we adapt existing theory to show that the asymptotic distribution for the likelihood ratio statistic is a mixture of chi-square distributions, and we derive the mixing probabilities. We conclude that when testing the AE or the CE model against the ACE model, the p-values obtained from using the chi(2)(1 df) as the reference distribution should be halved. When the E model is tested against the ACE model, a mixture of chi(2)(0 df), chi(2)(1 df) and chi(2)(2 df) should be used as the reference distribution, and we provide a simple formula to compute the mixing probabilities. Similar results for tests of the AE, DE and E models against the ADE model are also derived. Failing to use the appropriate reference distribution can lead to invalid conclusions.

A School-based Twin Study of Handedness among Adolescents in Taiwan

This study aimed to evaluate whether twinning might influence handedness and the relative contribution of genetic and environmental factors to handedness in a total of 321 pairs of twins, 36 same-sex sib-pairs, and 1020 singletons, aged 12-16 and systematically recruited from the junior high schools in Taipei. Twins' zygosity was determined by a combination of DNA typing and physical similarity. The direction and consistency of handedness in twins did not differ from that seen in singletons. Compared with the full model containing additive genes (A), shared (C), and non-shared (E) environment, both AE and CE models had equivalently acceptable fit. The contribution from additive genes in the AE model was estimated to be 16% (directional) to 13% (consistent) for the continuous handedness and 34-10% for the categorical one, whereas the corresponding contribution from shared environment in the CE model was 14-14% and 32-11%, respectively. Handedness in adolescents appears to be not influenced by twinning and not substantially heritable, whereas environmental factors, especially those not shared between siblings, are the most important ones for explaining individual variations.

Variations in Ce anomalies of conodonts through the Frasnian/Famennian boundary of Poland (Kowala – Holy Cross Mountains): implications for the redox state of seawater and biodiversity

Rare-earth element (REE) concentrations on Upper Devonian conodonts, distinguished by very low Color Alteration Index, were measured by inductively coupled plasma mass spectrometry from a stratigraphic section across the Frasnian/Famennian (F/F) boundary in the Holy Cross Mountains (Poland). The present data show a ‘hat-shaped’ pattern of the REE spectra similarly to other Devonian conodont spectra already documented. However, our sample composition suggests little to moderate alteration of the original oceanic pattern through the adsorption mechanism in a context of ‘weak’ or ‘early’ diagenesis. All along the section, the magnitude of the Ce anomaly is always negative, and there is an inverse correlation between the Ce anomaly and the (La/Sm) SN ratio. This has been interpreted as an La enrichment due to a terrestrial input. A mathematical procedure was used in order to restore the original Ce anomalies that would reflect the seawater environment not contaminated by terrestrial inputs. No noticeable change is observed in the Frasnian with homogeneous values of Ω(Ce) model but a sharp increase is initiated just below the F/F boundary with maximum values in the lowermost Famennian. The measured (La/Sm) SN ratios co-vary with the Ω(Ce) model in agreement with the hypothesis of a terrigenous input. Finally, the inverse correlation between the values of Ω(Ce) model and the relative abundance of Palmatolepis during the Famennian constitutes the first evidence known of a redox control on the presence of a conodont genus that is an indicator of deep-water environment.

Individual differences in handedness and specific speech and language impairment: evidence against a genetic link.

Data from two twin studies were used to address two related questions. First, is there any association between handedness and specific speech and language impairment (SSLI) in children? Second, is there genetic influence on individual differences in handedness and, if so, are the same genes implicated in the cause of SSLI? The first study used data from 58 MZ and 26 DZ pairs previously recruited for an investigation into the genetic origins of SSLI. All pairs contained at least one child with SSLI. Handedness was assessed using a preference inventory and a tapping task from which a laterality quotient (LQ) was derived. There were no handedness differences between these twins and 172 singleborn controls, and neither measure revealed any association between handedness and SSLI. The data were equally well-fitted by a CE model (no genetic influence) and an AE model (no effect of shared environment) for both hand preference and tapping LQ. Nonshared environment was the largest influence on handedness for both measures. Bivariate analysis indicated no overlapping genetic influences on SSLI and handedness. In the second study, handedness was assessed in a general population sample of 48 MZ and 44 DZ twin pairs, aged 7 to 13 years, using a preference inventory and a peg-moving task. A subset of children was also given a test that assessed persistence of hand preference when reaching across the midline. The latter was the only measure to relate to children's language status, with language-impaired children showing less midline crossing. This appears to reflect neurodevelopmental immaturity, rather than a stable trait. To investigate familial transmission of handedness, inventory data for parents and their twins were combined for both samples. The most parsimonious model was one that accounted for parent-child resemblance solely in terms of cultural transmission. Overall, there was no evidence that genes play a role in determining stable individual differences in hand preference. Insofar as there are links between handedness and speech and language difficulties, these reflect delayed neuromotor maturation.

Heritability of anxiety sensitivity: a twin study.

In attempting to explain the familial predisposition to panic disorder, most studies have focused on the heritability of physiologic characteristics (e.g., CO2 sensitivity). A heretofore unexplored possibility is that a psychological characteristic that predisposes to panic-anxiety sensitivity-might be inherited. In this study, the authors examined the heritability of anxiety sensitivity through use of a twin group. Scores on the Anxiety Sensitivity Index were examined in a group of 179 monozygotic and 158 dizygotic twin pairs. Biometrical model fitting was conducted through use of standard statistical methods. Broad heritability estimate of the Anxiety Sensitivity Index as a unifactorial construct was 45%. Additive genetic effects and unique environmental effects emerged as the primary influences on anxiety sensitivity. There was no evidence of genetic discontinuity between normal and extreme scores on the Anxiety Sensitivity Index. This study suggests that one psychological risk factor for the development of panic disorder-anxiety sensitivity-may have a heritable component. As such, anxiety sensitivity should be considered in future research on the heritability of panic disorder.

Multiple Ionisation and Fragmentation of Molecules

The multiple ionisation and dissociation of molecules, e.g. H2, N2, H2O, CH4 and C60, by fast ions was studied using a position- and time-sensitive multi-particle detector. The data obtained allow a clear separation of various reaction channels. Of special interest are the ‘Coulomb explosion’ processes like N2 → Nq+ +Nn+ or H2O → H+ + H+ +On+. For these reactions the coincident measurement of the momenta of correlated fragment ion yields a kinematically complete image of the molecular break-up process, and the fragmentation energy as well as angular correlations can be derived for each individual event. In the case of H2 as target molecule the CE model describes the fragmentation energy rather well, whereas in the case of more complex molecules, e.g. N2, CO and CH4, the simple CE model is insufficient to explain the measured energy and angular spectra. Better agreement was achieved with ab initio MCSCF calculations which take into account several molecular states of the fragmenting highly charged molecular ion.

Field evaporation in the configuration of a scanning tunneling microscope

The paper introduced an effective binding energy Λ′ eff and emphasized the role it plays in the field evaporation in the configuration of a scanning tunneling microscope (STM). With this Λ′ eff an important modification has been made to Tsong's CE model formula for STM [Tien T. Tsong, Phys. Rev. B 44 (1991) 13 703]. As a consequence, for tip–sample distance 5< d<13 Å, the high evaporation fields from Tsong's original formula were found greatly reduced. When d=7.23 Å, the recalculated evaporation field for Au −1 is 0.6 V/Å, which is in good agreement with Chang's experiment [Phys. Rev. Lett. 72 (1994) 574]. Further the evaporation field was found highly localized. For d=7.52 Å, the evaporation field of Au −1 on top of a Au(1 1 1) surface atom was found several times lower than that at a hollow site. In the calculation we have proposed a universal binding function. In addition selected experimental results on nanostructure formation by positive or negative voltage pulses with Au, Ni, Cu, Pt(Ir) and W tips on Au(1 1 1) substrate with a STM working in atmosphere were presented. The processes were found to bear important feature of field evaporation.

PCV14 Nonparametric Analysis of Cost-Effectiveness Ratios of Pravastatin in Primary Prevention of Cardiovascular Disease

OBJECTIVE: To obtain the confidence interval (CI) of the results of a cost-effectiveness model for the treatment of hypercholesterolemia. BACKGROUND: Incremental CE ratios play an important role in pharmacoeconomic analysis. However, CI estimates for the CE ratio are rare because the underlying distribution is unknown in most cases. Rather than using traditional one-way or multiway sensitivity analysis to explore estimate variability, a nonparametric bootstrap method is used to generate the CE ratio CI. This is more robust because it does not make parametric assumptions. METHODS: 1,000 bootstrap samples were drawn simultaneously with replacement from both an empirical distribution and a Monte Carlo experiment. For patient risk factors we used the complete subsample of men aged 45–64 fitting NCEP primary prevention guidelines in the National Health and Nutrition Examination Survey III. For model parameters (e.g., costs, discount rate) values were randomly drawn from a specified multivariate distribution. With 1,000 repeated estimates, the 26th and 975th ranked CE ratios were used to define the 95% confidence interval. Programming was done in Visual Basic for Applications (VBA) language. The study perspective was that of a third party payer. Efficacy and compliance data were obtained from the WOSCOPS clinical trial. The incremental 5-year cardiovascular health care costs were derived from a health insurer database. RESULTS: A 95% CI for the CE ratio resulting from the nonparametric bootstrap method showed that primary prevention of cardiovascular disease with pravastatin remained cost-effective. CONCLUSION: Confidence interval estimation for the CE ratio is important and will allow individuals to identify if a new intervention is a good value for cost, while capturing the inherent imprecision in the underlying CE model parameter values.

Pale0clim atlc estimate dur1ng the last 10000 years 1n eb1n ur la ke bas1 ．xlnjlang

本文应用水热平衡模型, 对艾比湖全新世时期三个高湖面期的降水量进行计算。结果表明, 2ka—3ka B.P.降水量比现今高出9％, 达到287mm/a;4.5ka—6ka B.P.增加16％, 达到306mm/a;6.5ka—8.0ka B.P.增加了22％, 达到322mm/a。;Judging from the analysis of lakeshure-geomopho1ogy and referring to the paleoelimate of selected section.in the past l 0000 years, Ebinur Lake experienced thfee stages of high lake-level:6.5ka- 8.0ka B.P..4.5ka-6.0ka B.P.and 2.0ka-3.Oka B.P..higher than that of present by 25m , 17m and.Responsively, their surfae areas were 3000 km² , 2330 km² and 1334 km² respectively.In this paper, in terms of a hydroingica l an d energy-balarlce med e1.the sensitivity of its param eters js discussed in detail, an d also, paleopre, cipitation of three high lake—level stages estim ated. Among these param eters lake c(Jefficient is the main factor affecthag the estim ation of paleoprecipitation.And lan d albedo, Bowen ratio and cloud cover also show high sensitive—But tem peratnre indicates relatively low sensitivity- By applying this hydrological an d energy’balan ce model, the estim ates of paleopreeipitation in different pe riods are obtained.In proper order, the average precipitation was:332 mm /a in 6.5 ka- 8, 0 ka B. P., an increase by 22 of the present;305 mm/a in 4.5 ka- 6.0 ka B.P., an incre&se by l6 and 287mm/a in 2.0-3.0 ka B.P., an increase by 9 of the present.

Estimation of Models with Correlated Measurement Errors from Panel Data

Single-indicator multiwave models provide one way to estimate the error variance of survey items. Two influential papers in the early 1970s (Wiley and Wiley 1970; Wiley and Wiley 1974) presented variations of such models for three waves of data. The first assumes that the only measurement error present is random (RE model). The second allows for correlated errors (CE model). The RE model has frequently been applied with useful results. The CE model, on the contrary, has rarely been used and tends to produce anomalous results. CE estimates based on only three waves of data are shown to be generally so sensitive to sampling error that they are uninformative. The standard errors of the CE model improve substantially when panels of four or more waves are used. This improvement, however, is contingent on the appropriateness of extending the rigid assumptions underlying the three-wave CE model to longer panels.

Electroanalytical investigations: Part VII . The simulation of fast chemical equilibrium reactions in cyclic voltammetric reaction-diffusion models with a combination of the heterogeneous equivalent technique and orthogonal collocation

Fast chemical equilibria coupled to an electron-transfer reaction are simulated for the boundary conditions of cyclic voltammetric models by a combination of the heterogeneous equivalent approach and orthogonal collocation. The resulting ordinary differential equation is reduced to a system of simultaneous equations. This system is solved for the boundary concentrations. These are used to integrate the partial differential equations describing diffusion to and from the electrode surface. The approach is exemplified by the EC and the CE model. The calculation results are verified by comparison to limiting cases and results from other simulation techniques. Simulations are performed using dimensionless rate constants of up to 10 10.