Multiple Source Method Research Articles

Comparing four methods to estimate usual intake distributions

The aim of this paper was to compare methods to estimate usual intake distributions of nutrients and foods. As 'true' usual intake distributions are not known in practice, the comparison was carried out through a simulation study, as well as empirically, by application to data from the European Food Consumption Validation (EFCOVAL) Study in which two 24-h dietary recalls (24-HDRs) and food frequency data were collected. The methods being compared were the Iowa State University Method (ISU), National Cancer Institute Method (NCI), Multiple Source Method (MSM) and Statistical Program for Age-adjusted Dietary Assessment (SPADE). Simulation data were constructed with varying numbers of subjects (n), different values for the Box-Cox transformation parameter (λ(BC)) and different values for the ratio of the within- and between-person variance (r(var)). All data were analyzed with the four different methods and the estimated usual mean intake and selected percentiles were obtained. Moreover, the 2-day within-person mean was estimated as an additional 'method'. These five methods were compared in terms of the mean bias, which was calculated as the mean of the differences between the estimated value and the known true value. The application of data from the EFCOVAL Project included calculations of nutrients (that is, protein, potassium, protein density) and foods (that is, vegetables, fruit and fish). Overall, the mean bias of the ISU, NCI, MSM and SPADE Methods was small. However, for all methods, the mean bias and the variation of the bias increased with smaller sample size, higher variance ratios and with more pronounced departures from normality. Serious mean bias (especially in the 95th percentile) was seen using the NCI Method when r(var) = 9, λ(BC) = 0 and n = 1000. The ISU Method and MSM showed a somewhat higher s.d. of the bias compared with NCI and SPADE Methods, indicating a larger method uncertainty. Furthermore, whereas the ISU, NCI and SPADE Methods produced unimodal density functions by definition, MSM produced distributions with 'peaks', when sample size was small, because of the fact that the population's usual intake distribution was based on estimated individual usual intakes. The application to the EFCOVAL data showed that all estimates of the percentiles and mean were within 5% of each other for the three nutrients analyzed. For vegetables, fruit and fish, the differences were larger than that for nutrients, but overall the sample mean was estimated reasonably. The four methods that were compared seem to provide good estimates of the usual intake distribution of nutrients. Nevertheless, care needs to be taken when a nutrient has a high within-person variation or has a highly skewed distribution, and when the sample size is small. As the methods offer different features, practical reasons may exist to prefer one method over the other.

Biomarker-based evaluation of two 24-h recalls for comparing usual fish, fruit and vegetable intakes across European centers in the EFCOVAL Study

A standardized methodology is important to enable consistent monitoring of dietary intake across European countries. For this reason, we evaluated the comparability of the assessment of usual food intake collected with two non-consecutive computerized 24-h dietary recalls (24-HDRs) and a food propensity questionnaire (FPQ) among five European centers. Two 24-HDRs using EPIC-Soft (the software developed to conduct 24-HDRs in the European Prospective Investigation into Cancer and Nutrition (EPIC) Study) were performed to determine fish, fruit and vegetable (FV) consumed by 600 adults in Belgium (BE), the Czech Republic (CZ), France (FR), the Netherlands (NL) and Norway (NO) in a validation study. An FPQ was used to identify non-consumers. Information from the 24-HDRs and FPQ were used to estimate individual usual food intake by the Multiple Source Method (MSM). Blood samples were drawn to determine fatty acids in phospholipids and serum carotenoids as biomarkers of fish, and FV intake, respectively. The pooled correlation between usual fish intake and eicosapentaenoic acid plus docosahexaenoic acid in phospholipids was 0.19 in men and 0.31 in women (P for heterogeneity >0.50) and center-specific correlations ranged between 0.08 (CZ) and 0.28 (BE and NO) in men, and between 0.19 (BE) and 0.55 (FR) in women. For usual FV intake, the pooled correlation with serum carotenoids was 0.31 in men and 0.40 in women (P for heterogeneity >0.10); the center-specific correlations varied between 0.07 (NO) and 0.52 (FR) in men, and between 0.25 (NL) and 0.45 (NO) in women. Two standardized 24-HDRs using EPIC-Soft and an FPQ appeared to be appropriate to rank individuals according to their fish and FV intake in a comparable way among five European centers.

Rationale and methods of the European Food Consumption Validation (EFCOVAL) Project

The overall objective of the European Food Consumption Validation (EFCOVAL) Project was to further develop and validate a trans-European food consumption method to be used for the evaluation of the intake of foods, nutrients and potentially hazardous chemicals within the European population. The EFCOVAL Project was carried out by 13 institutes from 11 European countries. The main activities were centered on the three main objectives of the project organized in different sub-projects. In EFCOVAL, EPIC-Soft (the software developed to conduct 24-h dietary recalls (24-HDRs) in the European Prospective Investigation into Cancer and Nutrition (EPIC) Study) was reprogrammed and adapted according to prioritized specifications, resulting in a software program working under the Windows operating system. In parallel of the EPIC-Soft development, the repeated 24-HDR method using EPIC-Soft and a food propensity questionnaire was evaluated against biomarkers in 24-h urine collections and in blood samples among adults from Belgium, the Czech Republic, (the South of) France, the Netherlands and Norway. As a result from an expert workshop on a proposed dietary assessment method for children (4-12 years), the suggested method was tested in a feasibility study in Denmark and Spain among children of 4-5, 7-8 and 12-13 years. To ensure that collected data had sufficient detail in food description for the assessment of additives and contaminants to foods the EPIC-Soft databases were adapted. Finally, the EFCOVAL Consortium developed a statistical tool (Multiple Source Method) for estimating the usual intake and distribution, which has been tested using real food consumption data and compared with three other statistical methods through a simulation study. In addition, a methodology was developed to quantify uncertainty due to portion-size estimation in usual intake distributions. The findings of EFCOVAL provide sufficient evidence to conclude that the repeated 24-HDR using EPIC-Soft for standardization in combination with a food propensity questionnaire and modeling of usual intake is a suitable method for pan-European surveillance of nutritional adequacy and food safety among healthy adults and maybe in children aged 7 years and older.

The European Food Consumption Validation Project: conclusions and recommendations

To outline and discuss the main results and conclusions of the European Food Consumption Validation (EFCOVAL) Project. The EFCOVAL Project was carried out within the EU Sixth Framework Program by researchers in 11 EU countries. The activities focused on (1) the further development of the EPIC-Soft software (the software developed to conduct 24-h dietary recalls (24-HDRs) in the European Prospective Investigation into Cancer and Nutrition (EPIC) Study) and the validation of the 2-day non-consecutive 24-HDR method using EPIC-Soft, (2) defining and investigating the applicability of the most appropriate dietary assessment method to younger age groups and expanding the applicability of the software for use in exposure assessment of some potentially hazardous chemicals and (3) to improve the methodology and statistical methods that estimate usual intake distributions from short-term dietary intake information and develop a methodology to quantify uncertainty in usual intake distributions. The preexisting EPIC-Soft application was reprogrammed into a Windows environment and more than 60 new specifications were implemented in the software. A validation study showed that two non-consecutive EPIC-Soft 24-HDRs are suitable to estimate the usual intake distributions of protein and potassium of European adult populations. The 2-day non-consecutive 24-HDRs in combination with a food propensity questionnaire also appeared to be appropriate to rank individuals according to their fish and fruit and vegetable intake in a comparable way in five European centers. Dietary intake of (young) children can be assessed by the combination of EPIC-Soft 24-HDRs and food recording booklets. The EPIC-Soft-standardized method of describing foods is useful to estimate dietary exposure to potentially hazardous chemicals such as specific flavoring substances. With the developed Multiple Source Method, repeated non-consecutive 24-HDR data in combination with food propensity data can be used to estimate the population distribution of the usual intake by estimating the individual usual intakes. The findings provide sufficient evidence to conclude that the repeated 24-HDR using EPIC-Soft for standardization in combination with a food propensity questionnaire and modeling of usual intake is a suitable method for pan-European surveillance of nutritional adequacy and food safety among healthy adults and maybe in children aged 7 years and older. To facilitate this methodology in other European countries, the next step is to provide and standardize an implementation plan that accounts for maintenance and updates, sampling designs, national surveillance programs, tailored capacity building and training, and linkage to food composition and occurrence databases.

Estimating Usual Food Intake Distributions by Using the Multiple Source Method in the EPIC-Potsdam Calibration Study1–3

Estimating usual food intake distributions from short-term quantitative measurements is critical when occasionally or rarely eaten food groups are considered. To overcome this challenge by statistical modeling, the Multiple Source Method (MSM) was developed in 2006. The MSM provides usual food intake distributions from individual short-term estimates by combining the probability and the amount of consumption with incorporation of covariates into the modeling part. Habitual consumption frequency information may be used in 2 ways: first, to distinguish true nonconsumers from occasional nonconsumers in short-term measurements and second, as a covariate in the statistical model. The MSM is therefore able to calculate estimates for occasional nonconsumers. External information on the proportion of nonconsumers of a food can also be handled by the MSM. As a proof-of-concept, we applied the MSM to a data set from the European Prospective Investigation into Cancer and Nutrition (EPIC)-Potsdam Calibration Study (2004) comprising 393 participants who completed two 24-h dietary recalls and one FFQ. Usual intake distributions were estimated for 38 food groups with a proportion of nonconsumers > 70% in the 24-h dietary recalls. The intake estimates derived by the MSM corresponded with the observed values such as the group mean. This study shows that the MSM is a useful and applicable statistical technique to estimate usual food intake distributions, if at least 2 repeated measurements per participant are available, even for food groups with a sizeable percentage of nonconsumers.

3D Sound Rendering for Multiple Sound Sources Based on Fuzzy Clustering

In this paper, we propose a new 3D sound rendering method for multiple sound sources with limited computational resources. The method is based on fuzzy clustering, which achieves dual benefits of two general methods based on amplitude-panning and hard clustering. In embedded systems where the number of reproducible sound sources is restricted, the general methods suffer from localization errors and/or serious quality degradation, whereas the proposed method settles the problems by executing clustering-process and amplitude-panning simultaneously. Computational cost evaluation based on DSP implementation and subjective listening test have been performed to demonstrate the applicability for embedded systems and the effectiveness of the proposed method.

Examining Duct Leakage on Prestressed Concrete Bridges via a Multiple Neutron Sources Method

Tendon corrosion and the leakage of water through the grouting voids are important contributors to the degradation of prestressed concrete (PC) bridges. Therefore, leakage inspections are beneficial in determining whether a tendon is corroding. This work addresses the inspection of duct leakages on PC bridges using a special multiple neutron source method. This approach is based on the principle of elastic collision between fast neutrons and hydrogen atoms during the emergence of thermalization. Multiple neutron sources should be combined with multiple detectors and an appropriately extended detection time. The probability of capturing thermal neutrons can thus be increased to inspect PC duct leakage. An equation was derived from a combination of theoretical studies and experimental outcomes as a reference for properly selecting the numbers of neutron sources and detectors as well as the detection time. The experimental results show that this approach increases the detection depth of leakage within concrete.

Mathematical framework for current density imaging due to discharge of electro-muscular disruption devices

Electro-muscular disruption (EMD) devices such as TASER M26 and X26 have been used as a less-than-lethal weapon. Such EMD devices shoot a pair of darts toward an intended target to generate an incapacitating electrical shock. In the use of the EMD device, there have been controversial questions about its safety and effectiveness. To address these questions, we need to investigate the distribution of the current density J inside the target produced by the EMD device. One approach is to develop a computational model providing a quantitative and reliable analysis about the distribution of J. In this paper, we set up a mathematical model of a typical EMD shock, bearing in mind that we are aiming to compute the current density distribution inside the human body with a pair of inserted darts. The safety issue of TASER is directly related to the magnitude of |J| at the region of the darts where the current density J is highly concentrated. Hence, fine computation of J near the dart is essential. For such numerical simulations, serious computational difficulties are encountered in dealing with the darts having two different very sharp corners, tip of needle and tip of barb. The boundary of a small fishhook-shaped dart inside a large computational domain and the presence of corner singularities require a very fine mesh leading to a formidable amount of numerical computations. To circumvent these difficulties, we developed a multiple point source method of computing J. It has a potential to provide effective analysis and more accurate estimate of J near fishhook-shaped darts. Numerical experiments show that the MPSM is just fit for the study of EMD shocks.

Synthesis and characterization of ternary AgInS2 nanocrystals by dual- and multiple-source methods

The precursors [In(bipy)(SC{O}Ph)3] and [Ag(SC{O}Ph)] have been used to prepare monodispersed polyhedral shaped AgInS2 nanocrystals (NCs). The NCs were fully characterized by X-ray powder diffraction, transmission electron microscopy, selected area electron diffraction and energy dispersive X-ray analysis. The synthesis of AgInS2 NCs was further investigated by varying the dual- and multiple-source precursors and other parameters such as surfactants, surfactant ratio, temperature and time duration, to optimize the conditions to get better quality NCs. In all these reactions, a heterobimetallic thiobenzoate intermediate similar to the single-source precursor [(Ph3P)2AgIn(SC{O}Ph)4] has been proposed to have formed which decompose subsequently to AgInS2 NCs.

独立成分分析とベイジアンネットを適用した電磁波到来角推定法による複数部分放電源の位置標定

We propose the new locating method for multiple partial discharge sources using independent component analysis (ICA) and direction of arrival method of electromagnetic (EM) waves based on Bayesian Network. The proposed method consists of the following steps. First, the observed signals are converted from the time domain to the frequency domain through the short time Fourier transform (STFT). As the result of this process, ICA for convolved mixture turns into ICA for instantaneous mixture. In order to separate mixed signals, we use the fast ICA algorithm (FastICA) that is based on negentropy as a measure of nongaussianity. Next, we apply the direction of arrival method of EM waves using Bayesian Network to the separated source signals by ICA. Signal sources are estimated by calculating intersection point from the arrival angle. Simulation results showed that our method located multiple signal sources when the observed signals were the convolved mixture of original sources.

PROBLEMS WITH ‘STRATEGY’ IN MICROSOCIAL HISTORY: FAMILIES AND NARRATIVES, SOURCES AND METHODS

This article considers the extent to which the concept of strategy may be applied in analyses of household and family behaviour. Strategy implies conscious, long-term decision making. However, such rationality is often difficult to discern, and when findings are compared using nominal record linkage across several sources elements of conflict and uncertainty emerge within families. A Scottish case study indicates the value of multiple-source methods in interpreting the complex relationships between individuals, households, work and welfare. Biographical profiles derived from Poor Law case histories indicate that both claimants and officials employed appropriate tactics to manage immediate circumstances. Nevertheless, the existence of long-term calculation based on collective household decisions cannot be demonstrated.

Multi-dimensional cosmological radiative transfer with a Variable Eddington Tensor formalism

We present a new approach to numerically model continuum radiative transfer based on the Optically Thin Variable Eddington Tensor (OTVET) approximation. Our method insures the exact conservation of the photon number and flux (in the explicit formulation) and automatically switches from the optically thick to the optically thin regime. It scales as N log N with the number of hydrodynamic resolution elements and is independent of the number of sources of ionizing radiation (i.e. works equally fast for an arbitrary source function). We also describe an implementation of the algorithm in a Soften Lagrangian Hydrodynamic code (SLH) and a multi-frequency approach appropriate for hydrogen and helium continuum opacities. We present extensive tests of our method for single and multiple sources in homogeneous and inhomogeneous density distributions, as well as a realistic simulation of cosmological reionization.

ERRATA

"A Multiple-Source Method for Studying the Prevalence of Developmental Disabilities in Children: The Metropolitan Atlanta Developmental Disabilities Study" by Yeargin-Allsopp et al appeared in the April issue of Pediatrics (1992;89:624-630). Some of the information presented in this article has been revised using updated population estimates of the metropolitan Atlanta area. In the abstract on page 624, the statistics in the sentence, "The prevalence rates found in this study, per 1000 10-year-old children, were as follows: mental retardation, 10.3; cerebral palsy, 2.0; hearing impairment, 1.0; and visual impairment, 0.6," should be changed to "mental retardation, 12.0; cerebral palsy, 2.3; hearing impairment, 1.1; and visual impairment, 0.7." On page 625, in the first paragraph under "Study Population," the text beginning "From September 1985 to August 1988,..." shold read "From September 1985 to August 1988, the years in which we identified children with DDs, there were approximately 30 000 10-year-old children in the five-county study area each year. Sixty-three percent of these children were white and 37% were races other than white; 52% of these children were male and 48% were female. The population data used for determining prevalence rates were estimated from Georgia population estimates (1985 through 1987)." On page 627, under "Results," "1441 DDs" should be changed to "1439 DDs." On Table 3, page 627, the number of children with cerebral palsy should be changed to 204. The prevalence rates on Table 3 should be changed to: mental retardation, 12.0; cerebral palsy, 2.3; visual impairment, 0.7; hearing impairment, 1.1.

Multiple cobalt 60 sources for treatment of carcinoma of the body of the uterus.

While a single intra-uterine tube, combined with vaginal sources, gives adequate irradiation to the cervix and the lower part of the body of the uterus, a different method is necessary if the upper part of the isodose curve is to be broadened so as to enclose the whole of the fundus. Many different techniques have been devised to produce this effect—the upper part of a single uterine tube may be loaded more heavily than the lower part (Tod and Morris, 1955), additional sources may be placed in each cornua (Hurdon, 1941), or special applicators may be constructed in which the radium is similarly arranged. The introduction of cobalt 60 has made possible the use of separate small sources without the need of added filtration, and Jones (1952) devised a special spring applicator loaded with such sources which after insertion through a cuff in the cervical canal expands to take the shape of the uterine cavity. All these techniques may prove unsatisfactory in advanced disease where the cavity of the uterus is distorted and the wall thickened and irregular, and in such cases a better distribution of radiation is obtained by the technique developed by Heyman (1947) (Figs. 4 and 5) in which the uterus is packed with a number of radium tubes enclosed in removable sleeves. A multiple source method similar to that of Heyman has been devised in which the uterus is packed with cobalt 60 sources mounted in Perspex beads (Fig. 1).