Showing papers by "Rider University published in 2018"

Drought timing and local climate determine the sensitivity of eastern temperate forests to drought

Abstract: Projected changes in temperature and drought regime are likely to reduce carbon (C) storage in forests, thereby amplifying rates of climate change. While such reductions are often presumed to be greatest in semi-arid forests that experience widespread tree mortality, the consequences of drought may also be important in temperate mesic forests of Eastern North America (ENA) if tree growth is significantly curtailed by drought. Investigations of the environmental conditions that determine drought sensitivity are critically needed to accurately predict ecosystem feedbacks to climate change. We matched site factors with the growth responses to drought of 10,753 trees across mesic forests of ENA, representing 24 species and 346 stands, to determine the broad-scale drivers of drought sensitivity for the dominant trees in ENA. Here we show that two factors-the timing of drought, and the atmospheric demand for water (i.e., local potential evapotranspiration; PET)-are stronger drivers of drought sensitivity than soil and stand characteristics. Drought-induced reductions in tree growth were greatest when the droughts occurred during early-season peaks in radial growth, especially for trees growing in the warmest, driest regions (i.e., highest PET). Further, mean species trait values (rooting depth and ψ50 ) were poor predictors of drought sensitivity, as intraspecific variation in sensitivity was equal to or greater than interspecific variation in 17 of 24 species. From a general circulation model ensemble, we find that future increases in early-season PET may exacerbate these effects, and potentially offset gains in C uptake and storage in ENA owing to other global change factors.

A New Look at an Old Cluster: The Membership, Rotation, and Magnetic Activity of Low-mass Stars in the 1.3 Gyr Old Open Cluster NGC 752

Abstract: The nearby open cluster NGC 752 presents a rare opportunity to study stellar properties at ages >1 Gyr. However, constructing a membership catalog for it is challenging; most surveys have been limited to identifying its giants and dwarf members earlier than mid-K. We supplement past membership catalogs with candidates selected with updated photometric and proper-motion criteria, generating a list of 258 members, a >50% increase over previous catalogs. Using a Bayesian framework to fit MESA Isochrones & Stellar Tracks evolutionary models to literature photometry and the Tycho-Gaia Astrometric Solution data available for 59 cluster members, we infer the age of, and distance to, NGC 752: 1.34$\pm$0.06 Gyr and 438$_{-6}^{+8}$ pc. We also report the results of our optical monitoring of the cluster using the Palomar Transient Factory. We obtain rotation periods for 12 K and M cluster members, the first periods measured for such low-mass stars with a well-constrained age >1 Gyr. We compare these new periods to data from the younger clusters Praesepe and NGC 6811, and to a theoretical model for angular-momentum loss, to examine stellar spin down for low-mass stars over their first 1.3 Gyr. While on average NGC 752 stars are rotating more slowly than their younger counterparts, the difference is not significant. Finally, we use our spectroscopic observations to measure Halpha for cluster stars, finding that members earlier than $\approx$M2 are magnetically inactive, as expected at this age. Forthcoming Gaia data should solidify and extend the membership of NGC 752 to lower masses, thereby increasing its importance for studies of low-mass stars.

Factor Structure of the 10 WISC-V Primary Subtests across Four Standardization Age Groups.

Abstract: The Wechsler Intelligence Scale for Children-Fifth Edition (WISC-V; Wechsler 2014a) Technical and Interpretation Manual (Wechsler 2014b) dedicated only a single page to discussing the 10-subtest WISC-V primary battery across the entire 6 to 16 age range. Users are left to extrapolate the structure of the 10-subtest battery from the 16-subtest structure. Essentially, the structure of the 10-subtest WISC-V primary battery remains largely uninvestigated particularly at various points across the developmental period. Using principal axis factoring and the Schmid–Leiman orthogonalization procedure, the 10-subtest WISC-V primary structure was examined across four standardization sample age groups (ages 6–8, 9–11, 12–14, 15–16). Forced extraction of the publisher’s promoted five factors resulted in a trivial fifth factor at all ages except 15–16. At ages 6 to 14, the results suggested that the WISC-V contains the same four first-order factors as the prior WISC-IV (Verbal Comprehension, Perceptual Reasoning, Working Memory, Processing Speed; Wechsler 2003). Results suggest interpretation of the Visual Spatial and Fluid Reasoning indexes at ages 6 to 14 may be inappropriate due to the fusion of the Visual Spatial and Fluid Reasoning subtests. At ages 15–16, the five-factor structure was supported. Results also indicated that the WISC-V provides strong measurement of general intelligence and clinical interpretation should reside primarily at that level. Regardless of whether a four- or five-factor index structure is emphasized, the group factors reflecting the WISC-V indices do not account for a sufficient proportion of variance to warrant primary interpretive emphasis.

Reliability and Factorial Validity of the Canadian Wechsler Intelligence Scale for Children--Fifth Edition.

Abstract: The reliability and factorial validity of the Wechsler Intelligence Scale for Children–Fifth Edition: Canadian (WISC-VCDN) was investigated. The higher-order model preferred by Wechsler (2014b) con...

Influence of sampling and disturbance history on climatic sensitivity of temperature-limited conifers

Abstract: Accurately capturing medium- to low-frequency trends in tree-ring data is vital to assessing climatic response and developing robust reconstructions of past climate. Non-climatic disturbance can af...

Association of soil selenium, strontium, and magnesium concentrations with Parkinson's disease mortality rates in the USA.

Abstract: Among the 41 soil elements analyzed from 4856 sites across the contiguous 48 states, average Parkinson’s disease (PD) mortality rates between 1999 and 2014 have the most significant positive correlation with the average soil strontium (Sr) concentrations (correlation r = 0.47, significance level p = 0.00), and average PD mortality rates have the most significant inverse correlation with the average soil selenium (Se) concentrations (r = −0.44, p = 0.00). Multivariate regression models indicate that soil Sr and Se concentrations can explain 35.4% of spatial disparities of the state average PD mortality rates between 1999 and 2014 (R 2 = 0.354). When the five outlier states were removed from the model, concentrations of soil Sr and Se can explain 62.4% (R 2 = 0.624) of the spatial disparities of PD mortality rates of the 43 remaining states. The results also indicate that high soil magnesium (Mg) concentrations suppressed the growth rate of the PD mortality rates between 1999 and 2014 in the 48 states (r = −0.42, p = 0.000). While both Se and Sr have been reported to affect the nervous system, this study is the first study that reported the statistically significant association between the PD mortality rates and soil concentrations of Se, Sr, and Mg in the 48 states. Given that soil elemental concentration in a region is broad indicator of the trace element intake from food, water, and air by people, implications of the results are that high soil Se and Mg concentrations helped reduce the PD mortality rates and benefited the PD patients in the 48 states.

An alternative conceptualization of the theoretical structure of the Woodcock-Johnson IV Tests of Cognitive Abilities at school age: A confirmatory factor analytic investigation.

Abstract: Confirmatory factor analysis produced a different theoretical conceptualization for the Woodcock-Johnson IV Tests of Cognitive Abilities (hereinafter, WJ IV Cognitive) in the age range between 9 to 19 years than the actual 7-factor theoretical structure presented in the instrument’s technical manual. Using maximum likelihood confirmatory factor analysis, the results of this study indicate that the WJ IV Cognitive measures 4 factors (Verbal, Working Memory, Perceptual Reasoning, and Processing Speed) and aligns with the prior Wechsler intelligence scales conceptualization of cognitive ability. The results also suggest that some caution should be exercised when moving to index-level interpretation as proposed in the WJ IV Technical Manual. Subtest alignment is different than what is proposed in the manual and the various indices do not account for sufficient variance for independent interpretive emphasis. The results of this study, therefore, have implications not only for direct CHC-index-level interpretation, but also for clinical interpretive approaches such as cross-battery assessment and processing strengths and weaknesses. S C I E N T I F I C A B S T R A C T The actual 7-factor theoretical structure of the Woodcock-Johnson Fourth Edition (WJ IV) Cognitive was not investigated by the test publisher. Instead, the structure for the WJ IV Cognitive battery was extrapolated from analyses of the full WJ IV test battery. The present study investigated the theoretical structure of the WJ IV Cognitive in isolation, using maximum likelihood confirmatory factor analysis applied to 2 standardization sample age groups (Age 9 to 13 and Age 14 to 19). The results of this study propose an alternate theoretical structure for the WJ IV Cognitive—one that aligns with the prior 4-factor conceptualizations of the Wechsler Scales (i.e., Verbal Ability, Working Memory, Processing Speed, and Perceptual Reasoning) rather than the 7-factor Cattell-Horn-Carroll (CHC) structure posited in the WJ IV Technical Manual. Implications for direct application of CHC-index-level interpretation and approaches to clinical interpretation, such as cross-battery assessment and processing strengths and weaknesses, are discussed.

Effects of urbanization on the population structure of freshwater turtles across the United States

Abstract: Landscape-scale alterations that accompany urbanization may negatively affect the population structure of wildlife species such as freshwater turtles. Changes to nesting sites and higher mortality rates due to vehicular collisions and increased predator populations may particularly affect immature turtles and mature female turtles. We hypothesized that the proportions of adult female and immature turtles in a population will negatively correlate with landscape urbanization. As a collaborative effort of the Ecological Research as Education Network (EREN), we sampled freshwater turtle populations in 11 states across the central and eastern United States. Contrary to expectations, we found a significant positive relationship between proportions of mature female painted turtles (Chrysemys picta) and urbanization. We did not detect a relationship between urbanization and proportions of immature turtles. Urbanization may alter the thermal environment of nesting sites such that more females are produced as urbanization increases. Our approach of creating a collaborative network of scientists and students at undergraduate institutions proved valuable in terms of testing our hypothesis over a large spatial scale while also allowing students to gain hands-on experience in conservation science.

Effects of Prenatal Care on Birth Outcomes: Reconciling a Messy Literature

Abstract: Research on the effects of prenatal care on birth outcomes has produced a patchwork of findings that are not easily summarized. Studies have used varying definitions of prenatal care, leading to estimates that are difficult to compare. The identification of causal effects is particularly challenging in this literature because women enter pregnancy with varying states of health, resources and the desire to have a child and it is not feasible to conduct randomized controlled trials that deny care. The content and quality of prenatal care can vary, even across individuals initiating care at the same point in their pregnancies and with similar medical and psychosocial issues. In this chapter, we review the literature on the effects of prenatal care on birth outcomes, highlighting studies with strong research designs and plausible effect sizes. We reconcile the findings to the extent possible, summarize what is known to date, and point to potentially fruitful research directions going forward.

A Misuse of IQ Scores: Using the Dual Discrepancy/Consistency Model for Identifying Specific Learning Disabilities

Abstract: The purpose of this article is to describe the origins of patterns of strengths and weaknesses (PSW) methods for identifying specific learning disabilities (SLD) and to provide a comprehensive review of the assumptions and evidence supporting the most commonly-used PSW method in the United States: Dual Discrepancy/Consistency (DD/C). Given their use in determining whether students have access to special education and related services, it is important that any method used to identify SLD have supporting evidence. A review of the DD/C evidence indicates it cannot currently be classified as an evidence-based method for identifying individuals with a SLD. We show that the DD/C method is unsound for three major reasons: (a) it requires test scores have properties that they fundamentally lack, (b) lack of experimental utility evidence supporting its use, and (c) evidence supporting the inability of the method to identify SLD accurately.

Fundamental Properties of Co-Moving Stars observed by $Gaia$

Abstract: We have estimated fundamental parameters for a sample of co-moving stars observed by $Gaia$ and identified by Oh et al. (2017). We matched the $Gaia$ observations to the 2MASS and WISE catalogs and fit MIST isochrones to the data, deriving estimates of the mass, radius, [Fe/H], age, distance and extinction to 9,754 stars in the original sample of 10,606 stars. We verify these estimates by comparing our new results to previous analyses of nearby stars, examining fiducial cluster properties, and estimating the power-law slope of the local present-day mass function. A comparison to previous studies suggests that our mass estimates are robust, while metallicity and age estimates are increasingly uncertain. We use our calculated masses to examine the properties of binaries in the sample, and show that separation of the pairs dominates the observed binding energies and expected lifetimes.

A New Look at an Old Cluster: The Membership, Rotation, and Magnetic Activity of Low-Mass Stars in the 1.3-Gyr-Old Open Cluster NGC 752

Abstract: The nearby open cluster NGC 752 presents a rare opportunity to study stellar properties at ages >1 Gyr. However, constructing a membership catalog for it is challenging; most surveys have been limited to identifying its giants and dwarf members earlier than mid-K. We supplement past membership catalogs with candidates selected with updated photometric and proper-motion criteria, generating a list of 258 members, a >50% increase over previous catalogs. Using a Bayesian framework to fit MESA Isochrones & Stellar Tracks evolutionary models to literature photometry and the Tycho-Gaia Astrometric Solution data available for 59 cluster members, we infer the age of, and distance to, NGC 752: 1.34$\pm$0.06 Gyr and 438$_{-6}^{+8}$ pc. We also report the results of our optical monitoring of the cluster using the Palomar Transient Factory. We obtain rotation periods for 12 K and M cluster members, the first periods measured for such low-mass stars with a well-constrained age >1 Gyr. We compare these new periods to data from the younger clusters Praesepe and NGC 6811, and to a theoretical model for angular-momentum loss, to examine stellar spin down for low-mass stars over their first 1.3 Gyr. While on average NGC 752 stars are rotating more slowly than their younger counterparts, the difference is not significant. Finally, we use our spectroscopic observations to measure Halpha for cluster stars, finding that members earlier than $\approx$M2 are magnetically inactive, as expected at this age. Forthcoming Gaia data should solidify and extend the membership of NGC 752 to lower masses, thereby increasing its importance for studies of low-mass stars.

Investigating the effect of a magnetic field on dose distributions at phantom-air interfaces using PRESAGE® 3D dosimeter and Monte Carlo simulations

Abstract: Dosimetric quality assurance (QA) of the new Elekta Unity (MR-linac) will differ from the QA performed of a conventional linac due to the constant magnetic field, which creates an electron return effect (ERE). In this work we aim to validate PRESAGE® dosimetry in a transverse magnetic field, and assess its use to validate the research version of the Monaco TPS of the MR-linac. Cylindrical samples of PRESAGE® 3D dosimeter separated by an air gap were irradiated with a cobalt-60 unit, while placed between the poles of an electromagnet at 0.5 T and 1.5 T. This set-up was simulated in EGSnrc/Cavity Monte Carlo (MC) code and relative dose distributions were compared with measurements using 1D and 2D gamma criteria of 3% and 1.5 mm. The irradiation conditions were adapted for the MR-linac and compared with Monaco TPS simulations. Measured and EGSnrc/Cavity simulated profiles showed good agreement with a gamma passing rate of 99.9% for 0.5 T and 99.8% for 1.5 T. Measurements on the MR-linac also compared well with Monaco TPS simulations, with a gamma passing rate of 98.4% at 1.5 T. Results demonstrated that PRESAGE® can accurately measure dose and detect the ERE, encouraging its use as a QA tool to validate the Monaco TPS of the MR-linac for clinically relevant dose distributions at tissue-air boundaries.

Investigating the theoretical structure of the DAS‐II core battery at school age using Bayesian structural equation modeling

Abstract: Bayesian structural equation modeling (BSEM) was used to investigate the latent structure of the DAS–II core battery using the standardization sample normative data for ages 7 to 17. Results revealed plausibility of a three-factor model, consistent with publisher theory, expressed as either a higher-order (HO) or a bifactor (BF) model. The results also revealed an alternative structure with the best model fit, a two-factor bifactor model with Matrices (MA) and Sequential & Quantitative Reasoning (SQ) loading on g only with no respective group factor loading. This was only the second study to use BSEM to investigate the structure of a commercial ability test and the first to use a large normative sample and the specification of both approximate zero cross-loadings and correlated residual terms.

Evolution of the Infant Health Production Function

Abstract: Michael Grossman's seminal publication on the demand for health and health production (Grossman 1972) has spawned a substantial body of research focusing on the production of infant health. This article provides a systematic review of the published literature to date on infant health production and how it has evolved over the past 3–4 decades as data have become more available, computing has improved, and econometric methods have become more sophisticated. While empirical research in most fields has expanded in corresponding ways, the infant health production research has become an important part of the broader and inherently multidisciplinary literature on intergenerational health. The strongest and most robust findings are that policies matter for infant health, particularly those affecting access to health care, and that prenatal smoking and other chemical exposures substantially compromise infant health. Promising directions for future research include elucidating relevant pathways, reconciling the largely inconsistent estimated effects of nutrition and education, and exploring the roles of preconceptional and lifetime health care, paternal factors, social support, housing, complementarity and substitutability of inputs, factors that modify effects of inputs, and evolving medical technologies.

Revisiting Carroll's survey of factor-analytic studies: Implications for the clinical assessment of intelligence.

Abstract: [Correction Notice: An Erratum for this article was reported in Vol 30(8) of Psychological Assessment (see record 2018-37729-003). In the article "Revisiting Carroll's Survey of Factor-Analytic Studies: Implications for the Clinical Assessment of Intelligence," by Nicholas F. Benson, A. Alexander Beaujean, Ryan J. McGill, and Stefan C. Dombrowski (Psychological Assessment, Advance online publication, May 24, 2018, http://dx.doi.org/10.1037/pas0000556), the majority of values in the ωH and ωHS columns of Table 4 were incorrect and have been amended. These revisions required text in the fourth paragraph of the Results section to be changed from "Moreover, the ωHS value for Gs is relatively high and very close to the and ωH values for g" to "Moreover, the ωHS values for Gs and Gv are relatively high, exceeding the ω and ωH values for g." All versions of this article have been corrected.] John Carroll's three-stratum theory (and the decades of research behind its development) is foundational to the contemporary practice of intellectual assessment. The present study addresses some limitations of Carroll's work: specification, reproducibility with more modern methods, and interpretive relevance. We reanalyzed select data sets from Carroll's survey of factor analytic studies using confirmatory factor analysis as well as modern indices of interpretive relevance. For the majority of data sets, we found that Carroll likely extracted too many factors representing Stratum II abilities. Moreover, almost all factors representing Stratum II abilities had little-to-no interpretive relevance above and beyond that of general intelligence. We conclude by discussing the implications of this research with respect to the interpretive relevance and clinical utility of scores reflecting cognitive abilities at all strata of the three-stratum theory and offer some directions for future research. (PsycINFO Database Record

Periodic Auxetics: Structure and Design.

Abstract: Materials science has adopted the term of auxetic behavior for structural deformations where stretching in some direction entails lateral widening, rather than lateral shrinking. Most studies, in the last three decades, have explored repetitive or cellular structures and used the notion of negative Poisson's ratio as the hallmark of auxetic behavior. However, no general auxetic principle has been established from this perspective. In the present article, we show that a purely geometric approach to periodic auxetics is apt to identify essential characteristics of frameworks with auxetic deformations and can generate a systematic and endless series of periodic auxetic designs. The critical features refer to convexity properties expressed through families of homothetic ellipsoids.

Infant Health and Future Childhood Adversity.

Abstract: Objective To investigate the extent to which disabling infant health conditions are associated with adverse childhood experiences at age 5. Methods We conducted a secondary analysis of data from the Fragile Families and Child Wellbeing Study, a national urban birth cohort. We estimated logistic regression models of associations between the presence of a disabling infant health condition and the child’s ACE exposures at age 5, controlling for factors that preceded the child’s birth, including the mother’s sociodemographic characteristics, physical health, mental illness, and substance abuse and the parents’ criminal justice system involvement and domestic violence or sexual abuse. ACEs included 4 categories of child maltreatment (physical, sexual, psychological abuse, neglect) and 5 categories of household dysfunction (father absence, substance use, mental illness, caregiver treated violently, incarceration). Results 3.3% of the children were characterized as having a disabling health condition that was likely present at birth. Logistic regression estimates indicate that having a disabling infant health condition was associated with 83% higher odds of the child experiencing 2 or more ACEs (AOR 1.83, CI 1.14–2.94) and 73% higher odds of the child experiencing 3 or more ACEs (AOR 1.73, CI 1.07–2.77) at age 5. Conclusions for Practice The finding of strong links between disabling infant health conditions and ACEs at age 5 suggests that child health and ACEs play intertwining and mutually reinforcing roles during the early lifecourse and highlights the critical importance of investing in systems that simultaneously promote optimal child development and address childhood adversity.

Handbook of Political Party Funding

Abstract: Scrutinizing a relatively new field of study, the Handbook of Political Party Funding assesses the basic assumptions underlying the research, presenting an unequalled variety of case studies from diverse political finance systems. With contributions from both eminent international scholars and prominent representatives of the second generation of students in the field, this original and thought-provoking collection of current research updates our understanding of party funding regimes, while contributing to the re-examination of perennial and often problematic issues. It illustrates, using select empirical data, the range of alternative political finance structures, exposing both the limits of these regimes and their effects on parties, systems and on democratic competition. Offering diverse and detailed case studies, the chapters examine the stakes involved nationally, and the impact of financing on the political environment. At the same time, they present a picture of a field of study that is still establishing itself, offering direction for future research. Students and academics of political science, public law and comparative politics will find this an essential reference for studying party funding and its wider influence. Members of political institutions and those fighting political corruption will find this an incredibly useful Handbook for understanding the positives and negatives of party funding globally

Factor Structure of the WISC-V in Four Standardization Age Groups: Exploratory and Hierarchical Factor Analyses with the 16 Primary and Secondary Subtests.

Abstract: 1Eastern Illinois University 2RiderUniversity 3BaylorUniversity Correspondence GaryL.Canivez, Ph.D., Professorof Psychology, Eastern IllinoisUniversity, DepartmentofPsychology, 600LincolnAvenue, Charleston, IL61920–3099. Email: glcanivez@eiu.edu Preliminary resultswerepresentedat the2015 AnnualConventionof theAmericanPsychologicalAssociation, Toronto,Ontario,Canada. Abstract This study examined the factor structure of the Wechsler Intelligence Scale for Children-Fifth Edition (WISC-V) with four standardization sample age groups (6–8, 9–11, 12–14, 15–16 years) using exploratory factor analysis (EFA), multiple factor extraction criteria, and hierarchical EFA not included in the WISC-V Technical and Interpretation Manual. Factor extraction criteria suggested that one to four factors might be sufficient despite the publisher-promoted, five-factor solution. Forced extraction of five factors resulted in only one WISC-V subtest obtaining a salient pattern coefficient on the fifth factor in all four groups, rendering it inadequate. Evidence did not support the publisher's desire to split Perceptual Reasoning into separateVisual Spatial and FluidReasoning dimensions. Results indicated that mostWISC-V subtests were properly associated with the four theoretically oriented first-order factors resembling theWISCIV, the g factor accounted for large portions of total and common variance, and the four first-order group factors accounted for small portions of total and common variance. Results were consistentwith EFA of theWISC-V total standardization sample.

Fundamental Properties of Co-moving Stars Observed by Gaia

Abstract: We have estimated fundamental parameters for a sample of co-moving stars observed by $Gaia$ and identified by Oh et al. (2017). We matched the $Gaia$ observations to the 2MASS and WISE catalogs and fit MIST isochrones to the data, deriving estimates of the mass, radius, [Fe/H], age, distance and extinction to 9,754 stars in the original sample of 10,606 stars. We verify these estimates by comparing our new results to previous analyses of nearby stars, examining fiducial cluster properties, and estimating the power-law slope of the local present-day mass function. A comparison to previous studies suggests that our mass estimates are robust, while metallicity and age estimates are increasingly uncertain. We use our calculated masses to examine the properties of binaries in the sample, and show that separation of the pairs dominates the observed binding energies and expected lifetimes.

Linked Data Technologies and What Libraries Have Accomplished So Far

Abstract: For the past ten years libraries have been working diligently towards Linked Data and the Semantic Web. Due to the complexity and vast scope of Linked Data, many people have a hard time to understand its technical details and its potential for the library community. This paper aims to help librarians better understand some important concepts by explaining the basic Linked Data technologies that consist of Resource Description Framework (RDF), the ontology, and the query language. It also includes an overview of the achievements by libraries around the world in their efforts to turn library data into Linked Data including those by Library of Congress, OCLC, and some other national libraries. Some of the challenges and setbacks that libraries have encountered are analyzed and discussed. In spite of the difficulties, there is no way to turn back. Libraries will have to succeed.

Behavioral Research with Planaria

Abstract: This article serves as a brief primer on planaria for behavior scientists. In the 1950s and 1960s, McConnell's planarian laboratory posited that conditioned behavior could transfer after regeneration, and through cannibalization of trained planaria. These studies, the responses, and replications have been collectively referred to as the "planarian controversy." Successful behavioral assays still require refinement with this organism, but they could add valuable insight into our conceptualization of memory and learning. We discuss how the planarian's distinctive biology enables an examination of biobehavioral interaction models, and what behavior scientists must consider if they are to advance behavioral research with this organism. Suggestions for academics interested in building planaria learning laboratories are offered.

Factor Structure of the CHC Model for the KABC-II: Exploratory Factor Analyses with the 16 Core and Supplementary Subtests

Abstract: The factor structure of the 16 core and supplementary Cattell-Horn-Carroll (CHC) model subtests for the Kaufman Assessment Battery for Children-Second Edition (KABC-II; Kaufman and Kaufman, 2004a) standardization sample samples aged 7–18 (N = 2025) was examined using exploratory factor analytic techniques (EFA) not included in the KABC-II manual (Kaufman and Kaufman, 2004b). The present results failed to replicate the five-factor CHC-based structure posited by the test publisher at school age. Factor extraction for the core battery suggested four factors, whereas five factors were supported for the total battery configuration. When these structures were transformed with the Schmid and Leiman (Psychometrika, 22, 53–61, 1957) orthgonalization procedure, the second-order general factor accounted for larger portions of total and common variance when compared to the reliable variance accounted for by the resulting four and five first-order factors. Users are encouraged to interpret the KABC-II primarily at the level of the Fluid-Crystallized Index (FCI), with additional consideration of the factor-based scores employed with more caution. Implications for clinical interpretation are discussed.

POHMM/SVM: A Hybrid Approach for Keystroke Biometric User Authentication

Abstract: There are mainly two kinds of statistical models are found in keystroke biometrics namely discriminative model and generative model. The support vector machine (SVM) is a popular discriminative models used in keystroke biometric systems for the last decade due to a higher accuracy rate for large datasets. On the other hand., the hidden Markov model (HMM)., a generative model., has proven to be a useful and efficient tool., especially in speech recognition. However., its performance is poor in keystroke biometrics compared to other models.. An extension of HMM - partially observable hidden Markov model (POHMM) has shown better performance in handling missing or infrequent data. In an attempt to reach efficiency., this study proposes a hybrid POHMM/SVM approach for user authentication taking advantage of both generative and discriminative models. POHMM has been used as the features extractor., and the one-class support vector machine as the anomaly detector. The proposed POHMM/SVM model has achieved 0.086 of average equal-error rate (EER) on CMU keystroke benchmark dataset across all subjects and the standard deviation is 0.063. Using the same evaluation procedure described in the supplemental paper for CMU benchmark keystroke dataset., the proposed model has shown substantial decrease in the EER over other published methods.