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The idea that a soothsayer may be able to know the unknown intrigues us, thanks in part to our natural fascination with the unknown.The unknown may be something that has happened in the past, but i...

Mixed models may be defined with or without reference to sampling, and can be used to predict realized random effects, as when estimating the latent values of study subjects measured with response error. When the model is specified without reference to sampling, a simple mixed model includes two random variables, one stemming from an exchangeable distribution of latent values of study subjects and the other, from the study subjects’ response error distributions. Positive probabilities are assigned to both potentially realizable responses and artificial responses that are not potentially realizable, resulting in artificial latent values. In contrast, finite population mixed models represent the two-stage process of sampling subjects and measuring their responses, where positive probabilities are only assigned to potentially realizable responses. A comparison of the estimators over the same potentially realizable responses indicates that the optimal linear mixed model estimator (the usual best linear unbias...

To investigate the effect of diet alone (D), exercise alone (E), and a combination of diet and exercise (DE) on body weight, body composition, energy intake, blood pressure, serum lipid and leptin levels, and fitness levels in mildly obese sedentary women and men.The three interventions were compared in a randomized longitudinal study design. The exercise programs were supervised for six months, after which participants in E and DE were provided with exercise equipment to take home.90 adult overweight women and men (age: 44.2 +/- 7.2 years; BMI = 30.5 +/- 2.7 kg/m(2)).Body weight, body composition, waist and hip circumferences, blood pressure, serum lipid levels, and fitness levels were evaluated at 0, 3, 6, 9, and 12 months. Serum leptin concentrations were measured at 0 and 6 months only.At 6 and 9 months in women, and 9 months in men, DE demonstrated a significant loss of body weight compared to both D and E (p0.05). Serum leptin levels significantly decreased from baseline to 6 months in women in D (p = 0.05) and DE (p = 0.0003) and men in E (p = 0.038). At one year, no significant differences existed among groups in any of the measures.A combination of diet and exercise resulted in a significant decrease in body weight in women and men; but this decrease was not maintained at one year follow-up. Serum leptin concentrations showed significant within-group decreases, but were not different among groups. A supervised diet and exercise program is effective for weight loss; however, once intensive participant-investigator and participant-participant contact is discontinued, weight regain ensures.

Tris(2-hydroxymethyl-4-oxo-4H-pyran-5-olato-κ2O5,O4)iron(III) [Fe(ka)3], has been characterised by magnetic susceptibility measurements Mossbauer and EPR spectroscopy. The crystal structure of [Fe(ka)3] has been determined by powder X-ray diffraction analysis. Magnetic susceptibility and EPR measurements indicated a paramagnetic high-spin iron centre. Mossbauer spectra revealed the presence of magnetic hyperfine interactions that are temperature-independent down to 4.2 K. The interionic Fe3+ distance of 7.31 A suggests spin-spin relaxation as the origin of these interactions.

The primary objective of this study was to describe eating patterns (e.g., breakfast, lunch, dinner, snacking, number of eating episodes, temporal patterns of eating across the 24-hour day, and the frequency of eating out) in a healthy U.S. population in order to provide a basis for future studies on the association between eating patterns and disease. Twenty-four hour dietary recalls were used to assess eating patterns, and cross-sectional analyses were conducted. Ninety-six percent of subjects usually consumed breakfast, 78% consumed lunch, 95% consumed dinner, and 60% consumed snacks. On average, participants ate 3.92 times daily (standard deviation(SD)=0.8). Caloric intake on weekend days was significantly greater than on weekdays. There was a tendency of participants to eat meals frequently outside of the home. The project described was supported by grant R01-HL52745 to Dr. Ira S. Ockene from the National Heart, Lung and Blood Institute (NHLBI). Its contents are solely the responsibility of the autho...

In many situations there is interest in parameters (e. g., mean) associated with the response distribution of individual clusters in a finite clustered population. We develop predictors of such parameters using a two-stage sampling probability model with response error. The probability model stems directly from finite population sampling without additional assumptions and thus is design-based. The predictors are closely related to best linear unbiased predictors (BLUP) that arise from common mixed-model methods, as well as to model-based predictors obtained via super population approaches for survey sampling. The context assumes clusters of equal size and equal size sampling of units within clusters. Target parameters may correspond to clusters realized in the sample, as well as nonrealized clusters. In either case, the predictors are linear and unbiased, and minimize the expected mean squared error. They correspond to the sum of predictors of responses for realized and nonrealized units in the cluster, a...

The EU Framework 5 project CONVECTION aims to understand convection processes in the Greenland Sea. By studying water motion close to the surface we hope to determine how convection is linked to atmospheric conditions andlocal surface features. The usual methods of studying such processes in the ocean are by taking multiple soundings of conductivity, temperature and pressure or towing a large chain measuring temperature and salinity through a cross-section of ocean. These have the disadvantage of yielding information only while the research vessel is in the area. We have employed an alternative acoustic method that can provide data for long periods using semi-permanent moorings. The acoustic shadowgraph method relies on the fact that when an acoustic signal propagates through a region containing convective irregularities the temperature variations along the path cause the signal amplitude to fluctuate. Unlike tomography, the shadowgraph does not require travel times to be measured and so the equipment can be much cheaper. This paper describes the experimental apparatus, its testing and deployment on Vesteris Bank in the Greenland Sea in October 2001 and its recovery in April 2002. It also gives an overview of some of the acoustic intensity results and shows how they can be interpreted to yield estimates of sub-surface convection velocities.

The scattering of an acoustic signal incident from below at low angles on a rough sea surface is treated by the integral equation method in the parabolic approximation. Equations are obtained allowing the mean scattered field to be calculated even when the surface causes a large phase modulation in the incident wave. Solutions are found using the method of Laplace transforms and some results are presented for a specific type of rough surface.

Soil ingestion estimates from mass balance soil ingestion studies can be used in Monte Carlo Risk assessment. We develop and describe a simulation model based on four mass balance soil ingestion studies that enables food ingestion, soil ingestion, and transit time to be mimicked. We use the simulation to evaluate potential biases that exist in current estimates of the distribution of daily soil ingestion in children (constructed from subject specific average daily estimates). The simulation identifies the importance of the study duration on the bias in the upper percentile soil ingestion estimates, indicating that the 95% soil ingestion estimate may be positively biased by over 100%. Misspecification of play areas for soil sampling is shown to have no biasing effect, and absorption of trace elements in food of up to 30% is shown to bias the soil ingestion distribution by less than 20 mg/d. The results, based on Al and Si trace element estimates, define the limits of previously published soil ingestion est...

Monte Carlo environmental risk assessment requires estimates of the exposure distributions. An exposure of principal concern is often soil ingestion among children. We estimate the long-term (annual) average soil ingestion exposure distribution using daily soil ingestion estimates from children who participated in a mass-balance study at Anaconda, MT. The estimated distribution is accompanied by uncertainty estimates. The estimates take advantage of developing knowledge about bias in soil ingestion estimates and are robust. The estimates account for small particle size soil, use the median trace element estimate for subject days, account for the small sample variance of the median estimates, and use best linear unbiased predictors to estimate the cumulative long term soil ingestion distribution. Bootstrapping is used to estimate the uncertainty of the distribution estimates. The median soil ingestion is estimated as 24 mg/d (sd = 4 mg/d), with the 95 percentile soil ingestion estimated as 91 mg/d (sd = 16...

This study was designed to characterize the acute nasal vasodilatory responses to the sensory irritants acetaldehyde and acetic acid. For this purpose, the upper respiratory tract of the urethane-anesthetized male F344 rat was isolated by insertion of an endotracheal cannula, and irritant-laden air was drawn continuously through that site at a flow rate of 100 ml/min for 50 min. Vascular function was monitored by measuring inert vapor (acetone) uptake throughout the exposure. Both acetaldehyde and acetic acid induced an immediate concentration-dependent vasodilation as indicated by increased steady-state acetone uptake rates. This response was observed at exposure concentrations of 25 ppm or 130 ppm or higher for acetaldehyde or acetic acid, respectively. The response to either vapor was significantly diminished in rats pretreated with the sensory nerve toxin capsaicin (50 mg/kg, 7 days prior to exposure), providing evidence that sensory nerves play a role in the response. Acetaldehyde is metabolized by aldehyde dehydrogenase to acetic acid. Pretreatment with the aldehyde dehydrogenase inhibitor cyanamide (10 mg/kg, 1 h prior to exposure) reduced the vasodilatory response to 200 ppm but not to 50 ppm acetaldehyde. These results suggest that formation of acetic acid is important in the sensory nerve-mediated vasodilatory response to high, but perhaps not to low, concentrations of acetaldehyde.

This investigation assessed the effect of soil particle size on soil ingestion estimates of children residing at a superfund site. Earlier research indicated that wide intertracer variability in so...

Ingestion of non-food items/mouthing behavior results in exposure of children to contaminants in soil/dust. We characterize the prevalence of such behaviors in healthy children. The relative frequency of such behaviors was assessed by parent interviews for 533 children age 1 to 6. Thirty-eight percent of children put soil in their mouths at least monthly, 24% at least weekly, and 11% daily. High-risk behavior decreased quickly for children aged 2 or more, but was still reported at least monthly by 3 to 9% of parents of children up through age 6. Highest outdoor object mouthing rates occur among 1-year-old children, who are reported to play daily in sand/dirt and have generally high levels of mouthing. Such children may have higher soil/dust ingestion and higher exposure to contaminants when soil/dust contains lead or other agents. These high-risk groups may help focus educational interventions and/or risk assessments.

Random sampling of a finite population of subjects leads to observed values on the selected subjects. When the measure on a subject includes response error, the observed response for a selected subject can be distinguished from the latent value representing the subject’s parameter. We derive linear unbiased minimum MSE estimates of a realized subject’s latent value from sample data, where these data are considered to have arisen from three possible sample spaces: a space conditional on the realized sample subjects; a space conditional on a single realized subject in the sample; and a space unconditional on the realized sample subjects. The derivation results in the ordinary mean estimate (BLUE) for the first two sample spaces, and the best linear unconditionally unbiased estimate (BLUUE) commonly referred to as the best linear unbiased predictor (BLUP) for the third sample space. Focusing on estimates of a single realized subject’s latent value and the second sample space, we identify a range of latent pa...

A-4166, a phenylalanine derivative, is a hypoglycemic agent, which has been shown to improve blood glucose levels mainly due to the rapid and short term stimulation of insulin release. Nevertheless, a possible extrapancreatic action of A-4166 has not yet been investigated. Therefore, insulin action (euglycemic hyperinsulinemic 6.4 mU.kg-1.min-1 clamp plus 3H-2-deoxyglucose tracer administration) was studied after 3 weeks on either standard (BD) or high fat (HF) diet in normal control (C) or in hereditary insulin resistant (hHTg) rats which were given a single dose of A-4166 (10 mg per kg BW, i.v.) 60 min after clamp commencement. HF feeding reduced the glucose infusion rate (GIR) required to maintain euglycemia to about 50% of C (p < 0.001). In hHTg rats, HF did not further pronounce the pre-existing decrease of GIR of hHTg animals fed BD. A-4166 changed GIR neither in C, nor in the hHTg group. The estimated glucose disposal (Rd) (C-BD: 32.3 +/- 1.9 vs C-HF: 25.5 +/- 1.9 mg.kg-1.min-1, p < 0.001) and glucose metabolic index (Rg') in skeletal muscles (Q. femoris: C-BD: 25.6 +/- 1.5 vs C-HF: 12.3 +/- 1.1 mmol.100 g-1.min-1, p < 0.001) were reduced by HF in control rats but were not restored by a concomitant bolus of A-4166. Nevertheless, in hHTg rats fed the HF diet a single dose of A-4166 brought back their Rd (hHTg-HF: 23.5 +/- 1.3 vs hHTg-HF plus A-4166: 31.0 +/- 3.5 p < 0.03) and Rg' (Soleus muscle: hHTg-HF: 29.2 +/- 3.2 vs hHTg-HF plus A-4166: 41.3 +/- 4.0) to values of the control group on BD. In summary, a) a single bolus administration of A-4166 to the control or to the insulin resistant hHTg rats, fed either the BD or HF diets, did not abolish the reduction of GIR required to maintain euglycemia during hyperinsulinemic clamps; b) nevertheless, A-4166 caused a significant increase of the estimated plasma glucose disposal (Rd) and skeletal muscle glucose metabolic index (Rg') of hHTG rats fed the HF diet; c) we suggest that A-4166 may have an extrapancreatic action but this needs to be proven using a long-term administration plan of A-4166.

Soil ingestion was estimated over seven consecutive days in a soil tracer‐based mass‐balance methodology in 12 children, aged 1 to 3 years. The children had been identified by parents as likely high soil ingesters based on retrospective observation of daily soil ingestion behavior over the past 30 d. While one of the 12 children displayed high soil ingestion (0.5 to 3.05 g/d) on 4 of 7 d, median soil ingestion rates for the 12 children were comparable to those published in other soil ingestion studies of young children selected for studies based on age and not assumed or observed soil ingestion behavior. The lack of ability of parental judgments to predict high soil ingestion rates represents both an important observation and a significant limitation in current methods to efficiently and accurately identify children who ingest high amounts of soil.

Monte Carlo studies of risk assessment commonly require estimates of exposure distributions. The exposure distribution may be estimated by assuming the distribution follows a specified functional form (lognormal), and estimating parameters of the assumed distribution from observed sample exposure data. Alternatively, to avoid the distributional assumption, the exposure distribution may be estimated directly from the observed exposures measured on a sample of subjects. We discuss problems with this second approach for estimating exposure distributions when exposures are measured with error. Specifically, we show that when the true exposure varies from day to day, or the observed exposure differs from the true exposure due to measurement error, then the tails of the observed exposure distributions will be biased, with the magnitude of the bias increasing toward the tails of the distribution. The bias may be severe, and lead to overestimation of upper percentile exposure. The size of the bias is dir...

This paper develops a novel methodology, the Best Tracer method (BTM), that substantially overcomes the principal limitations (intertracer inconsistencies, and poor precision of recovery) of estimating soil ingestion by specific soil‐based tracers in massbalance studies. The BTM incorporates a biological and statistical framework that improves precision of recovery of tracer estimates, markedly reducing input‐output misalignment error resulting from a lack of correspondence between food tracer input and fecal tracer output. This method is then used to re‐estimate the soil ingestion distribution of previously published soil ingestion estimates from two children studies (Calabrese et al. 1989; Davis et al., 1990) and one adult study (Calabrese et al., 1990). Revised estimates of soil ingestion are provided for each study. In addition, the results from the two children's studies are combined to form a single estimate of the soil ingestion distribution. These collective findings result in more reliab...

The formation of a soil ingestion distribution based on pooling data from current soil ingestion studies is appealing. An important issue in forming such a distribution is what to do with negative soil ingestion estimates for particular subjects, because they comprise approximately 10 to 40% of the total soil ingestion estimates. A method of correcting for the negative estimates of soil ingestion is to make use of the “soil ingestion detection limit”;. An appropriate methodology for forming estimates of such detection limits is available in the literature. This paper discusses appropriate use of the existing soil ingestion detection limit methodology in forming a pooled database using current soil ingestion study data. The discussion focuses attention on the current limitations of children's soil ingestion data and potential pitfalls in applying the detection limit model when generating a soil ingestion distribution. In summary, currently available soil ingestion data are not sufficiently reliabl...

The observation that Zr provided an estimate of soil ingestion 80% lower than estimates provided by seven other elements for 1 week in a soil‐pica child in light of the apparent high detection capability for the element resulted in a reexamination of the validity of a current modeling approach advocated for use in estimating soil ingestion detection limits. This examination reveals that for high levels of soil ingestion, possible biases in soil ingestion methodology may be inadequately accounted for in the soil detection limit model. The extent of this limitation is explored and placed in the context of reported limitations in trace element measurement methodology.

This paper provides a critical assessment of the ability of soil ingestion studies to provide reliable quantitative estimates of soil ingestion. It also identifies principal causes of both inter‐study and inter‐tracer variability in soil ingestion estimates and applies this knowledge to the previous published soil ingestion studies of Calabrese et al. (1989). The paper concludes by providing a decision framework for estimating soil ingestion rates within the context of age of subjects, urban vs rural, seasonality, normal vs soil pica behavior and other considerations affecting soil ingestion rates.

This paper presents evidence that normal children aged 1–4, who were participating in a study designed to estimate soil ingestion, displayed very elevated fecal vanadium (V) levels that could not be explained by consumption of food, water, medicine, or soil. Some children were exposed to V that exceeded average daily food ingestion of V by 50‐ 500‐fold. The source of the V is uncertain but is hypothesized to be related at least in part to consumption of inks and print in childrens’ books. Previous assessments of daily V exposure in children have not considered this novel source of exposure and have prematurely concluded food to be the principal environmental source of V in young children.

This paper proposes a new method for providing quantitative estimates for soil ingestion based on studies using mass‐balance methodologies. The method selects the lowest food to soil tracer ingestion ratio for a subject‐week as the “best tracer” ratio based on the concept for the potential for precision of recovery. This approach will yield a single soil ingestion estimate per subject‐week as well as for population‐based estimates. It is expected to yield a marked improvement in the precision of recovery and lower soil ingestion detection for soil ingestion studies. This approach is designed to overcome recognized problems in current soil ingestion studies in which most tracer soil ingestion estimates were below the soil ingestion detection limit of such studies due principally to high food to soil tracer ingestion ratios.

The paper critiques a 1988 dissertation by Wong (1) of soil pica amongst Institutionalized children on the Island of Jamaica. The Wong dissertation presents the most extensive data yet of soil pica with respect to both numbers of children (six) displaying soil pica and the duration of study (4 months). Amongst children of normal mental capabilities with an average age of 3.1 years, 5 of 24 (20.8%) displayed soil pica behavior (i.e., > 1 g soil Ingested/day) on at least one occasion. In addition, 10.5% of all observations of these 24 children Involved soil Ingestion of > 1 gm/day. Emphasis is given to the Wong dissertation because It has essentially escaped notice amongst those researching and critiquing In the area of soil Ingestion most likely because its emphasis was directed toward exposure to parasites having a life‐cycle stage in soil and not chemical contaminants.

A previously published report on soil ingestion in children revealed evidence that one of the subjects, a 3.5 year old female, displayed soil‐pica behavior (Calabrese et al., 1989). Subsequent analysis of the soil‐pica child data revealed that soil‐pica occurred only during week two of the two‐week study during which she ingested 10–13 grams of soil per day (Calabrese et al., 1991) and that over 90% of the soil ingested was of outdoor versus indoor (i.e. dust) origin (Calabrese and Stanek, 1992). The present study revealed that on days when the child displayed soil‐pica behavior she also displayed striking increases in fecal lead excretory values that could not be explained by other sources of lead exposure (e.g. food). The linking of soil ingestion and lead exposure in the soil‐pica child was supported by temporal relationship as well as the magnitude of the change in both soil based fecal tracer excretion and fecal lead excretion. This paper represents the first report to our knowledge of the q...

Simultaneous exposure to chemicals which can oxidize hemoglobin to methemoglobin is common. Although the effects of these agents have been extensively documented Individually, little research considers their potential Interactive effects. In vitro experimentation on female Dorset sheep erythrocytes assessed the Interactive capacity of copper and chlorite and copper and nitrite to affect methemoglobin formation. All combinations of doses which produced 1.25, 2.5, 5, 10 and 15 percent methemoglobin and controls were tested. These evaluations therefore, included data on each chemical alone and their respective two‐way combinations. The responses observed were principally additive In nature (the sum of the Individual effects). However, the statistical analysis of the copper and chlorite Joint exposure rejected the addltlvlty hypothesis displaying a modest degree of antagonism.

This report estimated the amount of outdoor soil in indoor dust in the Calabrese et al. (1989) children soil ingestion study via the use of statistical modelling. The estimate used data on outdoor soil and indoor dust in the homes of 60 children with eight tracer elements (Al, Ba, Mn, Si, Ti, V, Y, and Zr). The model estimated that 31.3% of indoor dust had an origin of outdoor soil. Based on a previous report (Stanek and Calabrese, 1992) on differential soil from dust ingestion in the Calabrese et al. (1989) study and the data of the present analysis, the median outdoor soil ingestion of the Calabrese et al. (1989) study should be revised downward by 35%. For the three most reliable tracers, the median soil ingestion estimates would be reduced from 29 to 19 mg/d for Al, 55 to 36 mg/d for Ti, and 16 to 10 mg/d for, Zr.

Four major studies have attempted to qualitatively and quantitatively assess the extent of soil ingestion in children using the soil tracer methodology. The validity of the estimates of soil ingestion of each study was reevaluated in light of the inherent strengths and limitations of study design and/or execution as well as via a novel methodology to estimate the soil recovery variance of each tracer which then lead to the estimation of soil ingestion detection limits of each tracer for studies performing mass-balance analyses. Based on these analyses it is concluded that the Binder et al. (1986) and Van Wijnen et al. (1990) studies provide no convincing evidence to support qualitative and quantitative estimates of soil ingestion due to inherent limitations of their respective study designs. The Davis et al. (1990) and Calabrese et al. (1989) studies displayed convincing qualitative evidence of soil ingestion. However, the results indicate that the median soil ingestion estimates of Davis et al. w...

Methodological considerations play an important role in forming population estimates of soil ingestion in children. Two important areas of controversy are the hypothesized log-normal distribution of ingested soil and the identificatbn and appropriateness of methods for handling outliers. Each of these issues is discussed in the context of data collected on soil ingestion in Amherst, Massachusetts. Non-parametric methods are recommended as most suitable and appropriate for analysis of soil ingestion studies.

Pretest-posttest designs serve as building blocks for other more complicated repeated-measures designs. In settings where subjects are independent and errors follow a bivariate normal distribution, data analysis may consist of a univariate repeated-measures analysis or an analysis of covariance. Another possible analysis approach is to use seemingly unrelated regression (SUR). The purpose of this article is to help guide the statistician toward an appropriate analysis choice. Assumptions, estimates, and test statistics for each analysis are approached in a systematic manner. On the basis of these results, the crucial choice of analysis is whether differences in pretest group means are conceived to be real or the result of pure measurement error. Direct consultation of the statistician with a subject-matter person is important in making the right choice. If pretest group differences are real, then a univariate repeated-measures analysis is recommended. If pretest group differences are the result o...

The fuel shortage has encouraged the utilization of high sulfur fuels in those facilities where they can be used in an environmentally safe manner. A study was undertaken by the State of Iowa to correlate sulfur content of coals, stack heights, and maximum ground level concentrations from power plants. This study revealed that the primary National Ambient Air Quality Standards for SO2 are more restrictive than the secondary standard in almost all cases. This conclusion is contrary to the position that the attainment of the secondary standard could beata later date than the attainment of the primary standards.

During the autumn of 1975, the Iowa Department of Environmental Quality conducted a study to determine the impact of the open burning of leaves on local air quality in the Des Moines (Iowa) metropolitan area. The results of the study show that open burning can cause excesses of National Ambient Air Quality Standards for particulates and carbon monoxide in heavily populated residential areas.