The Residential Population Generator (RPGen): Parameterization of Residential, Demographic, and Physiological Data to Model Intraindividual Exposure, Dose, and Risk

Exposure to chemicals is influenced by associations between the individual’s location and activities as well as demographic and physiological characteristics. Currently, many exposure models simulate individuals by drawing distributions from population-level data or use exposure factors for single individuals. The Residential Population Generator (RPGen) binds US surveys of individuals and households and combines the population with physiological characteristics to create a synthetic population. In general, the model must be supported by internal consistency; i.e., values that could have come from a single individual. In addition, intraindividual variation must be representative of the variation present in the modeled population. This is performed by linking individuals and similar households across income, location, family type, and house type. Physiological data are generated by linking census data to National Health and Nutrition Examination Survey data with a model of interindividual variation of parameters used in toxicokinetic modeling. The final modeled population data parameters include characteristics of the individual’s community (region, state, urban or rural), residence (size of property, size of home, number of rooms), demographics (age, ethnicity, income, gender), and physiology (body weight, skin surface area, breathing rate, cardiac output, blood volume, and volumes for body compartments and organs). RPGen output is used to support user-developed chemical exposure models that estimate intraindividual exposure in a desired population. By creating profiles and characteristics that determine exposure, synthetic populations produced by RPGen increases the ability of modelers to identify subgroups potentially vulnerable to chemical exposures. To demonstrate application, RPGen is used to estimate exposure to Toluene in an exposure modeling case example.

Motor Reaction Times as an Embedded Measure of Performance Validity: a Study with a Sample of Austrian Early Retirement Claimants

Among embedded measures of performance validity, reaction time parameters appear to be less common. However, their potential may be underestimated. In the German-speaking countries, reaction time is often examined using the Alertness subtest of the Test of Attention Performance (TAP). Several previous studies have examined its suitability for validity assessment. The current study was conceived to examine a variety of reaction time parameters of the TAP Alertness subtest with a sample of 266 Austrian civil forensic patients. Classification results from the Word Memory Test (WMT) were used as an external indicator to distinguish between valid and invalid symptom presentations. Results demonstrated that the WMT fail group performed worse in reaction time as well as its intraindividual variation across trials when compared to the WMT pass group. Receiver operating characteristic analyses revealed areas under the curve of .775–.804. Logistic regression models indicated the parameter intraindividual variation of motor reaction time with warning sound as being the best predictor for invalid test performance. Suggested cut scores yielded a sensitivity of .62 and a specificity of .90, or .45 and .95, respectively, when the accepted false-positive rate was set lower. The results encourage the use of the Alertness subtest as an embedded measure of performance validity.

Personality dynamics

Traditionally, personality psychology has been understood as the study of stability in people’s dispositions. However, a different strand of personality research has highlighted the importance of acknowledging and explaining the meaningful intraindividual variation in human thoughts, feelings, and behavior across different contexts and time. The goal of this paper is to review this strand, highlight current research, and outline key questions for future research. We summarize historical perspectives on the dynamic processes underlying the emergence of personality within and across individuals (e.g. the pioneering theorizing of Allport; the person-situation debate), recent theoretical and empirical advances in incorporating dynamic processes into the definition and assessment of personality (e.g., the study of personality states; dynamic approaches to personality including Cognitive Affective Personality System [CAPS], Whole Trait Theory, the Knowledge-and-Appraisal Personality Architecture [KAPA] framework, and Nonlinear Interaction of Person and Situation [NIPS]), and new directions in current research (e.g. idiographic approaches; understanding variability in narrative identity). We end with suggestions for future research.

First cytogenetic characterization of the Amazon Catfish Leiarius marmoratus (Gill, 1870) and its hybrid with Pseudoplatystoma reticulatum (Eigenmann & Eigenmann, 1889)

This study reports the first cytogenetic characterization of the Amazonian catfish Leiarius marmoratus (“jandiá”) and its F1 (first generation) hybrid “cachandiá” with Pseudoplatystoma reticulatum (“cachara”). A diploid number of 56 chromosomes and a single argyrophilic nucleolus organizer region (Ag-NOR) in the short arm of two sub-telocentric chromosomes were observed for both L. marmoratus and P. reticulatum, but with differences in the karyotype formula and the size of the chromosome pair with NORs. The hybrid showed 2n = 56 chromosomes with an intermediate karyotype when compared to the parental species. A single Ag-NOR was maintained in the hybrid but located in two chromosomes with marked differences in size and presenting intraindividual variation in NOR activity (nucleolar dominance). For L. marmoratus and the hybrid, heterochromatic bands were predominately distributed in the terminal, centromeric, and sub-centromeric regions of some chromosomes and 5S rDNA sites located in two distinct sub-telocentric chromosomes, similar to the previously described for P. reticulatum. The data suggested that the hybrid karyotype might be insufficient for a precise discrimination of hybrids, however, Ag-NOR can be used as a chromosome marker to differentiate “cachandiá” from L. marmoratus and P. reticulatum. The current study also provides insights into the chromosomal features of L. marmoratus and contributes with novel cytogenetic information of this native Amazonian catfish included in the Pimelodidae family.

Seven day pre-analytical stability of serum and plasma neurofilament light chain

Neurofilament light chain (NfL) has emerged as a biomarker of neuroaxonal damage in several neurologic conditions. With increasing availability of fourth-generation immunoassays detecting NfL in blood, aspects of pre-analytical stability of this biomarker remain unanswered. This study investigated NfL concentrations in serum and plasma samples of 32 patients with neurological diagnoses using state of the art Simoa technology. We tested the effect of delayed freezing of up to 7 days and statistically determined stability and validity of measured concentrations. We found concentrations of NfL in serum and plasma to remain stable at room temperature when processing of samples is delayed up to 7 days (serum: mean absolute difference 0.9 pg/mL, intraindividual variation 1.2%; plasma: mean absolute difference 0.5 pg/mL, intraindividual variation 1.3%). Consistency of these results was nearly perfect for serum and excellent for plasma (intraclass correlation coefficients 0.99 and 0.94, respectively). In conclusion, the soluble serum and plasma NfL concentration remains stable when unprocessed blood samples are stored up to 7 days at room temperature. This information is essential for ensuring reliable study protocols, for example, when shipment of fresh samples is needed.

Sometimes Hot, Sometimes Not: The Relations between Selected Situational Vocational Interests and Situation Perception

Vocational interests are traditionally conceived as stable preferences for different activities. However, recent theorizing suggests their intraindividual variability. This preregistered experience sampling study examined intraindividual variation in selected vocational interests states and related situation and person factors ( N = 237). Results indicate that the three interest dimensions Investigative, Artistic, and Social interests did vary intraindividually but less so than other phenomena's dimensions (e.g., personality and happiness). At the within–person level, the focused interest states were related to specific situation characteristics, also after controlling for related personality dimensions and happiness. These relations were either specified a priori, based on the concept of congruence or person–environment fit, and tested in a strictly confirmatory manner, or identified using a more exploratory approach. Furthermore, aggregated states of the three selected interest dimensions mainly varied below their corresponding trait levels. This suggests that interest trait levels could represent an upper limit for aggregated interest states that could be due to method–related or construct–related reasons. The results demonstrate the situational character of interests and provide novel approaches for studying vocational interest in daily life. © 2020 The Authors. European Journal of Personality published by John Wiley & Sons Ltd on behalf of European Association of Personality Psychology

Dialects, registers and intraindividual variation: Outside the scope of generative frameworks?

This article explores intraindividual microvariation in dialect syntax. We argue that in many cases the speaker has internalized a different (sub)grammar for each dialectal variety, in line with the hypothesis of universal bilingualism and parallel grammars argued for by Roeper (1999 et seq.). We discuss the question of how we can distinguish parallel grammars from optionality within one grammar, suggesting that the identification of correlating contextual factors might be a promising criterion. However, we also explore a more subtle type of variation, namely cases where a standard variety influences a potentially more vulnerable non-standard variety in a way that makes it exceedingly difficult for the language user and even for a trained linguist to discern what is what. We discuss whether or not these properties should be analysed as properties of another subgrammar (the standard grammar) or as fully integrated (albeit acquired) properties of the non-standard dialect.

Serum neurofilament light chain withstands delayed freezing and repeated thawing

Serum neurofilament light chain (sNfL) and its ability to expose axonal damage in neurologic disorders have solicited a considerable amount of attention in blood biomarker research. Hence, with the proliferation of high-throughput assay technology, there is an imminent need to study the pre-analytical stability of this biomarker. We recruited 20 patients with common neurological diagnoses and 10 controls (i.e. patients without structural neurological disease). We investigated whether a variation in pre-analytical variables (delayed freezing up to 24 h and repeated thawing/freezing for up to three cycles) affects the measured sNfL concentrations using state of the art Simoa technology. Advanced statistical methods were applied to expose any relevant changes in sNfL concentration due to different storing and processing conditions. We found that sNfL concentrations remained stable when samples were frozen within 24 h (mean absolute difference 0.2 pg/ml; intraindividual variation below 0.1%). Repeated thawing and re-freezing up to three times did not change measured sNfL concentration significantly, either (mean absolute difference 0.7 pg/ml; intraindividual variation below 0.2%). We conclude that the soluble sNfL concentration is unaffected at 4–8 °C when samples are frozen within 24 h and single aliquots can be used up to three times. These observations should be considered for planning future studies.

On the importance of intraindividual variation in nutritional research

Nutritional intervention studies, like those with pre- and probiotics, are often hampered by low effect sizes, reducing the power to demonstrate potential efficacy. Here, we perform computer simulations of a hypothetical clinical trial using such an intervention in order to elucidate determining factors that can be influenced in order to optimise the statistical power. Our simulations demonstrate that steering the study population towards a low intraindividual variation dramatically improves statistical power. A more than 10-fold decrease of number-to-treat could be reached. Also, a careful balancing between the number of subjects and measurements per subject, in combination with possible stratification of the subjects into responders and non-responders, based on inherent intraindividual variation, improves the likelihood to reach statistically significant results. Our results also show that traditional dogmas, with respect to clinical trials, i.e. aiming at low interindividual variation and a high number (n) of study participants, should be re-evaluated in favour of reducing intraindividual variation. This reduction in intraindividual variation could be achieved by maintaining a steady lifestyle, including dietary habits among others, within the timeframe of the intervention study.