Science.gov

Sample records for numa rede unidimensional

  1. Assessing Unidimensionality of Polytomous Data.

    ERIC Educational Resources Information Center

    Nandakumar, Ratna; Yu, Feng; Li, Hsin-Hung; Stout, William

    1998-01-01

    Investigated the performance of the Poly-DIMTEST (PD) procedure (and associated computer program) in assessing the unidimensionality of test data produced by polytomous items through Monte Carlo simulation. Results show that PD can confirm unidimensionality for unidimensional simulated data and can detect lack of unidimensionality. (SLD)

  2. Unidimensional Interpretations for Multidimensional Test Items

    ERIC Educational Resources Information Center

    Kahraman, Nilufer

    2013-01-01

    This article considers potential problems that can arise in estimating a unidimensional item response theory (IRT) model when some test items are multidimensional (i.e., show a complex factorial structure). More specifically, this study examines (1) the consequences of model misfit on IRT item parameter estimates due to unintended minor item-level…

  3. Parallel Analysis with Unidimensional Binary Data

    ERIC Educational Resources Information Center

    Weng, Li-Jen; Cheng, Chung-Ping

    2005-01-01

    The present simulation investigated the performance of parallel analysis for unidimensional binary data. Single-factor models with 8 and 20 indicators were examined, and sample size (50, 100, 200, 500, and 1,000), factor loading (.45, .70, and .90), response ratio on two categories (50/50, 60/40, 70/30, 80/20, and 90/10), and types of correlation…

  4. NUMA: A Northern Paiute History.

    ERIC Educational Resources Information Center

    Inter-Tribal Council of Nevada, Reno.

    One in a series of four histories of native Nevadans, this volume presents the story of the Northern Paiute people, or Numa, who lived, hunted, and travelled in the Great Basin area which occupies one-third of present day Nevada and parts of Oregon, Idaho, and California. Based on interviews with tribal elders and research conducted at numerous…

  5. An Assessment of Stout's Index of Essential Unidimensionality.

    ERIC Educational Resources Information Center

    Hattie, John; And Others

    1996-01-01

    A simulation study was conducted to evaluate the dependability of the "T" index of unidimensionality developed by W. F. Stout and used in his DIMTEST procedure. DIMTEST was found to provide dependable indications of unidimensionality, to be reasonably robust, and to allow for practical demarcation between one and many dimensions. (SLD)

  6. Unidimensional continuous-variable quantum key distribution

    NASA Astrophysics Data System (ADS)

    Usenko, Vladyslav C.; Grosshans, Frédéric

    2015-12-01

    We propose the continuous-variable quantum key distribution protocol based on the Gaussian modulation of a single quadrature of the coherent states of light, which is aimed to provide simplified implementation compared to the symmetrically modulated Gaussian coherent-state protocols. The protocol waives the necessity in one of the quadrature modulations and the corresponding channel transmittance estimation. The security of the protocol against collective attacks in a generally phase-sensitive Gaussian channel is analyzed and is shown achievable upon certain conditions. Robustness of the protocol to channel imperfections is compared to that of the symmetrical coherent-state protocol. The simplified unidimensional protocol is shown possible at a reasonable quantitative cost in terms of key rate and of tolerable channel excess noise.

  7. Are Utilitarian/Deontological Preferences Unidimensional?

    PubMed Central

    Laakasuo, Michael; Sundvall, Jukka

    2016-01-01

    Utilitarian versus deontological inclinations have been studied extensively in the field of moral psychology. However, the field has been lacking a thorough psychometric evaluation of the most commonly used measures. In this paper, we examine the factorial structure of an often used set of 12 moral dilemmas purportedly measuring utilitarian/deontological moral inclinations. We ran three different studies (and a pilot) to investigate the issue. In Study 1, we used standard Exploratory Factor Analysis and Schmid-Leimann (g factor) analysis; results of which informed the a priori single-factor model for our second study. Results of Confirmatory Factor Analysis in Study 2 were replicated in Study 3. Finally, we ran a weak invariance analysis between the models of Study 2 and 3, concluding that there is no significant difference between factor loading in these studies. We find reason to support a single-factor model of utilitarian/deontological inclinations. In addition, certain dilemmas have consistent error covariance, suggesting that this should be taken into consideration in future studies. In conclusion, three studies, pilot and an invariance analysis, systematically suggest the following. (1) No item needs to be dropped from the scale. (2) There is a unidimensional structure for utilitarian/deontological preferences behind the most often used dilemmas in moral psychology, suggesting a single latent cognitive mechanism. (3) The most common set of dilemmas in moral psychology can be successfully used as a unidimensional measure of utilitarian/deontological moral inclinations, but would benefit from using weighted averages over simple averages. (4) Consideration should be given to dilemmas describing infants. PMID:27582721

  8. The Puzzling Unidimensionality of DSM-5 Substance Use Disorder Diagnoses

    PubMed Central

    MacCoun, Robert J.

    2013-01-01

    There is a perennial expert debate about the criteria to be included or excluded for the DSM diagnoses of substance use dependence. Yet analysts routinely report evidence for the unidimensionality of the resulting checklist. If in fact the checklist is unidimensional, the experts are wrong that the criteria are distinct, so either the experts are mistaken or the reported unidimensionality is spurious. I argue for the latter position, and suggest that the traditional reflexive measurement model is inappropriate for the DSM; a formative measurement model would be a more accurate characterization of the institutional process by which the checklist is created, and a network or causal model would be a more appropriate foundation for a scientifically grounded diagnostic system. PMID:24324446

  9. Developing an Essentially Unidimensional Test with Cognitively Designed Items

    ERIC Educational Resources Information Center

    Bryant, Damon U.; Wooten, William

    2006-01-01

    The purpose of this study was to demonstrate how cognitive and measurement principles can be integrated to create an essentially unidimensional test. Two studies were conducted. In Study 1, test questions were created by using the feature integration theory of attention to develop a cognitive model of performance and then manipulating complexity…

  10. An Empirical Study of Various Indices for Determining Unidimensionality.

    ERIC Educational Resources Information Center

    Hattie, John

    1984-01-01

    This paper describes a simulation that determines the adequacy of various indices as decision criteria for assessing unidimensionality. Using the sum of absolute residuals from the two-parameter latent trait model, indices were obtained that could discriminate between one latent trait and more than one latent trait. (Author/BW)

  11. Delimiting Coefficient a from Internal Consistency and Unidimensionality

    ERIC Educational Resources Information Center

    Sijtsma, Klaas

    2015-01-01

    I discuss the contribution by Davenport, Davison, Liou, & Love (2015) in which they relate reliability represented by coefficient a to formal definitions of internal consistency and unidimensionality, both proposed by Cronbach (1951). I argue that coefficient a is a lower bound to reliability and that concepts of internal consistency and…

  12. Bayesian Estimation of Multi-Unidimensional Graded Response IRT Models

    ERIC Educational Resources Information Center

    Kuo, Tzu-Chun

    2015-01-01

    Item response theory (IRT) has gained an increasing popularity in large-scale educational and psychological testing situations because of its theoretical advantages over classical test theory. Unidimensional graded response models (GRMs) are useful when polytomous response items are designed to measure a unified latent trait. They are limited in…

  13. Essential Unidimensionality Examination for Multicomponent Scales: An Interrelationship Decomposition Approach

    ERIC Educational Resources Information Center

    Raykov, Tenko; Pohl, Steffi

    2013-01-01

    A procedure for examining essential unidimensionality in multicomponent measuring instruments is discussed. The method is based on an application of latent variable modeling and is concerned with the extent to which a common factor for all components of a given scale accounts for their correlations. The approach provides point and interval…

  14. Application of Unidimensional Item Response Models to Tests with Items Sensitive to Secondary Dimensions

    ERIC Educational Resources Information Center

    Zhang, Bo

    2008-01-01

    In this research, the author addresses whether the application of unidimensional item response models provides valid interpretation of test results when administering items sensitive to multiple latent dimensions. Overall, the present study found that unidimensional models are quite robust to the violation of the unidimensionality assumption due…

  15. Identification and characterization of novel NuMA isoforms

    SciTech Connect

    Wu, Jin; Xu, Zhe; He, Dacheng; Lu, Guanting

    2014-11-21

    Highlights: • Seven NuMA isoforms generated by alternative splicing were categorized into 3 groups: long, middle and short. • Both exons 15 and 16 in long NuMA were “hotspot” for alternative splicing. • Lower expression of short NuMA was observed in cancer cells compared with nonneoplastic controls. • Distinct localization pattern of short isoforms indicated different function from that of long and middle NuMA. - Abstract: The large nuclear mitotic apparatus (NuMA) has been investigated for over 30 years with functions related to the formation and maintenance of mitotic spindle poles during mitosis. However, the existence and functions of NuMA isoforms generated by alternative splicing remains unclear. In the present work, we show that at least seven NuMA isoforms (categorized into long, middle and short groups) generated by alternative splicing from a common NuMA mRNA precursor were discovered in HeLa cells and these isoforms differ mainly at the carboxyl terminus and the coiled-coil domains. Two “hotspot” exons with molecular mass of 3366-nt and 42-nt tend to be spliced during alternative splicing in long and middle groups. Furthermore, full-length coding sequences of long and middle NuMA obtained by using fusion PCR were constructed into GFP-tagged vector to illustrate their cellular localization. Long NuMA mainly localized in the nucleus with absence from nucleoli during interphase and translocated to the spindle poles in mitosis. Middle NuMA displayed the similar cell cycle-dependent distribution pattern as long NuMA. However, expression of NuMA short isoforms revealed a distinct subcellular localization. Short NuMA were present in the cytosol during the whole cycle, without colocalization with mitotic apparatus. These results have allowed us tentatively to explore a new research direction for NuMA’s various functions.

  16. Robustness of the Polytomous IRT Model to Violations of the Unidimensionality Assumption.

    ERIC Educational Resources Information Center

    Dawadi, Bhaskar R.

    The robustness of the polytomous Item Response Theory (IRT) model to violations of the unidimensionality assumption was studied. A secondary purpose was to provide guidelines to practitioners to help in deciding whether to use an IRT model to analyze their data. In a simulation study, the unidimensionality assumption was deliberately violated by…

  17. The Use of Unidimensional Item Parameter Estimates of Multidimensional Items in Adaptive Testing.

    ERIC Educational Resources Information Center

    Ackerman, Terry A.

    The purpose of this study was to investigate the effect of using multidimensional items in a computer adaptive test (CAT) setting which assumes a unidimensional item response theory (IRT) framework. Previous research has suggested that the composite of multidimensional abilities being estimated by a unidimensional IRT model is not constant…

  18. A Comparison Study of the Unidimensional IRT Estimation of Compensatory and Noncompensatory Multidimensional Item Response Data.

    ERIC Educational Resources Information Center

    Ackerman, Terry A.

    Concern has been expressed over the item response theory (IRT) assumption that a person's ability can be estimated in a unidimensional latent space. To examine whether or not the response to an item requires only a single latent ability, unidimensional ability estimates were compared for data generated from the multidimensional item response…

  19. Exploring Unidimensional Proficiency Classification Accuracy from Multidimensional Data in a Vertical Scaling Context

    ERIC Educational Resources Information Center

    Kroopnick, Marc Howard

    2010-01-01

    When Item Response Theory (IRT) is operationally applied for large scale assessments, unidimensionality is typically assumed. This assumption requires that the test measures a single latent trait. Furthermore, when tests are vertically scaled using IRT, the assumption of unidimensionality would require that the battery of tests across grades…

  20. Statistical distribution of bonding distances in a unidimensional solid

    NASA Astrophysics Data System (ADS)

    Belousov, Roman; De Gregorio, Paolo; Rondoni, Lamberto; Conti, Livia

    2014-10-01

    We study a Fermi-Pasta-Ulam-like chain with Lennard-Jones potentials to model a unidimensional solid in contact with heat baths at a given temperature. We formulate an explicit analytical expression for the probability density of bonding distances between neighboring particles, which depends on temperature similarly to the distribution of velocities. For a finite number of particles, its validity is verified with high accuracy through molecular dynamics simulations. We also provide a theoretical framework which is consistent with the numerical findings. We give an analytic expression of the mean bond distance and elastic constant in the case of the square-well and harmonic interparticle potentials: we outline the role played by the hard-core repulsion. We also calculate the same quantities in the case of series expansions of Lennard-Jones potential truncated at different, even series power.

  1. The Effect of NUMA Tunings on CPU Performance

    NASA Astrophysics Data System (ADS)

    Hollowell, Christopher; Caramarcu, Costin; Strecker-Kellogg, William; Wong, Antonio; Zaytsev, Alexandr

    2015-12-01

    Non-Uniform Memory Access (NUMA) is a memory architecture for symmetric multiprocessing (SMP) systems where each processor is directly connected to separate memory. Indirect access to other CPU's (remote) RAM is still possible, but such requests are slower as they must also pass through that memory's controlling CPU. In concert with a NUMA-aware operating system, the NUMA hardware architecture can help eliminate the memory performance reductions generally seen in SMP systems when multiple processors simultaneously attempt to access memory. The x86 CPU architecture has supported NUMA for a number of years. Modern operating systems such as Linux support NUMA-aware scheduling, where the OS attempts to schedule a process to the CPU directly attached to the majority of its RAM. In Linux, it is possible to further manually tune the NUMA subsystem using the numactl utility. With the release of Red Hat Enterprise Linux (RHEL) 6.3, the numad daemon became available in this distribution. This daemon monitors a system's NUMA topology and utilization, and automatically makes adjustments to optimize locality. As the number of cores in x86 servers continues to grow, efficient NUMA mappings of processes to CPUs/memory will become increasingly important. This paper gives a brief overview of NUMA, and discusses the effects of manual tunings and numad on the performance of the HEPSPEC06 benchmark, and ATLAS software.

  2. Critical Path-Based Thread Placement for NUMA Systems

    SciTech Connect

    Su, Chun-Yi; Li, Dong; Nikolopoulos, Dimitrios; Grove, Matthew; Cameron, Kirk W.; de Supinski, Bronis R.

    2012-01-01

    Multicore multiprocessors use Non Uniform Memory Architecture (NUMA) to improve their scalability. However,NUMA introduces performance penalties due to remote memory accesses. Without efficiently managing data layout and thread mapping to cores, scientific applications, even if they are optimized for NUMA, may suffer performance loss. In this paper, we present an algorithm that optimizes the placement of OpenMP threads on NUMA processors. By collecting information from hardware counters and defining new metrics to capture the effects of thread placement, the algorithm reduces NUMA performance penalty by minimizing the critical path of OpenMP parallel regions and by avoiding local memory resource contention. We evaluate our algorithm with NPB benchmarks and achieve performance improvement between 8.13% and 25.68%, compared to the OS default scheduling.

  3. HYPERS: A Unidimensional Asynchronous Framework for Multiscale Hybrid Simulations

    NASA Astrophysics Data System (ADS)

    Omelchenko, Y. A.; Karimabadi, H.; Vu, H. X.

    2011-12-01

    Kinetic ion-driven processes are crucial for understanding the complex dynamics of the closely coupled Earth magnetosphere-ionosphere system. Largely varying time and length scales impose severe numerical constraints on global simulations with hybrid (particle ions + fluid electrons) codes. To enable larger simulations we developed a unique, uni-dimensional multiscale hybrid code, HYPERS. Instead of stepping all simulation variables uniformly in time, HYPERS tracks physically meaningful changes to individual particles and cell-based electromagnetic fields via asynchronous discrete events. HYPERS has been parallelized with the Preemptive Event Processing (PEP) technique. The parallel algorithm enables arbitrary domain decompositions and processor configurations on restarts. This is a critical prerequisite for implementing a full load balancing functionality in the future. We validate HYPERS by simulating the interaction of streaming plasmas with dipole magnetospheres and show that our approach results in superior numerical metrics (stability, accuracy and speed) compared to conventional techniques. We also discuss further extensions to the HYPERS framework that would enable seemless integration of ion fluid and kinetic schemes.

  4. Increasing Item Complexity: A Possible Cause of Scale Shrinkage for Unidimensional Item Response Theory.

    ERIC Educational Resources Information Center

    Yen, Wendy M.

    1985-01-01

    An approximate relationship is devised between the unidimensional model used in data analysis and a multidimensional model hypothesized to be generating the item responses. Scale shrinkage is successfully predicted for several sets of simulated data. (Author/LMO)

  5. Critical Path-Based Thread Placement for NUMA Systems

    SciTech Connect

    Su, C Y; Li, D; Nikolopoulos, D S; Grove, M; Cameron, K; de Supinski, B R

    2011-11-01

    Multicore multiprocessors use a Non Uniform Memory Architecture (NUMA) to improve their scalability. However, NUMA introduces performance penalties due to remote memory accesses. Without efficiently managing data layout and thread mapping to cores, scientific applications, even if they are optimized for NUMA, may suffer performance loss. In this paper, we present algorithms and a runtime system that optimize the execution of OpenMP applications on NUMA architectures. By collecting information from hardware counters, the runtime system directs thread placement and reduces performance penalties by minimizing the critical path of OpenMP parallel regions. The runtime system uses a scalable algorithm that derives placement decisions with negligible overhead. We evaluate our algorithms and runtime system with four NPB applications implemented in OpenMP. On average the algorithms achieve between 8.13% and 25.68% performance improvement compared to the default Linux thread placement scheme. The algorithms miss the optimal thread placement in only 8.9% of the cases.

  6. Target Rotations and Assessing the Impact of Model Violations on the Parameters of Unidimensional Item Response Theory Models

    ERIC Educational Resources Information Center

    Reise, Steven; Moore, Tyler; Maydeu-Olivares, Alberto

    2011-01-01

    Reise, Cook, and Moore proposed a "comparison modeling" approach to assess the distortion in item parameter estimates when a unidimensional item response theory (IRT) model is imposed on multidimensional data. Central to their approach is the comparison of item slope parameter estimates from a unidimensional IRT model (a restricted model), with…

  7. Performance of Parallel Analysis in Retrieving Unidimensionality in the Presence of Binary Data

    ERIC Educational Resources Information Center

    Tran, Ulrich S.; Formann, Anton K.

    2009-01-01

    Parallel analysis has been shown to be suitable for dimensionality assessment in factor analysis of continuous variables. There have also been attempts to demonstrate that it may be used to uncover the factorial structure of binary variables conforming to the unidimensional normal ogive model. This article provides both theoretical and empirical…

  8. The Greatest Lower Bound to the Reliability of a Test and the Hypothesis of Unidimensionality

    ERIC Educational Resources Information Center

    Berge, Jos M. F. Ten; Socan, Gregor

    2004-01-01

    To assess the reliability of congeneric tests, specifically designed reliability measures have been proposed. This paper emphasizes that such measures rely on a unidimensionality hypothesis, which can neither be confirmed nor rejected when there are only three test parts, and will invariably be rejected when there are more than three test parts.…

  9. Effect of Violating Unidimensional Item Response Theory Vertical Scaling Assumptions on Developmental Score Scales

    ERIC Educational Resources Information Center

    Topczewski, Anna Marie

    2013-01-01

    Developmental score scales represent the performance of students along a continuum, where as students learn more they move higher along that continuum. Unidimensional item response theory (UIRT) vertical scaling has become a commonly used method to create developmental score scales. Research has shown that UIRT vertical scaling methods can be…

  10. Development and Validation of a Unidimensional Maltreatment Scale in the Add Health Data Set

    ERIC Educational Resources Information Center

    Marszalek, Jacob M.; Hamilton, Jessica L.

    2012-01-01

    Four maltreatment items were examined from Wave III (N = 13,516) of the National Longitudinal Study of Adolescent Health. Item analysis, confirmatory factor analysis, cross-validation, reliability estimates, and convergent validity coefficients strongly supported the validity of using the four items as a unidimensional composite. Implications for…

  11. Assessing Model Data Fit of Unidimensional Item Response Theory Models in Simulated Data

    ERIC Educational Resources Information Center

    Kose, Ibrahim Alper

    2014-01-01

    The purpose of this paper is to give an example of how to assess the model-data fit of unidimensional IRT models in simulated data. Also, the present research aims to explain the importance of fit and the consequences of misfit by using simulated data sets. Responses of 1000 examinees to a dichotomously scoring 20 item test were simulated with 25…

  12. The Asymptotic Distribution of Ability Estimates: Beyond Dichotomous Items and Unidimensional IRT Models

    ERIC Educational Resources Information Center

    Sinharay, Sandip

    2015-01-01

    The maximum likelihood estimate (MLE) of the ability parameter of an item response theory model with known item parameters was proved to be asymptotically normally distributed under a set of regularity conditions for tests involving dichotomous items and a unidimensional ability parameter (Klauer, 1990; Lord, 1983). This article first considers…

  13. Circular Unidimensional Scaling: A New Look at Group Differences in Interest Structure

    ERIC Educational Resources Information Center

    Armstrong, Patrick Ian; Hubert, Lawrence; Rounds, James

    2003-01-01

    The fit of J. L. Holland's (1959, 1997) RIASEC model to U.S. racial-ethnic groups was assessed using circular unidimensional scaling. Samples of African American, Asian American, Caucasian American and Hispanic American high school students and employed adults who completed either the UNIACT Interest Inventory (K. B. Swaney, 1995) or the Strong…

  14. Evaluation of Scale Reliability for Unidimensional Measures Using Latent Variable Modeling

    ERIC Educational Resources Information Center

    Raykov, Tenko

    2009-01-01

    This article outlines a readily and widely applicable procedure of reliability evaluation for scales with unidimensional measures. The method is developed within the framework of the popular latent variable modeling methodology, and it accomplishes point, as well as interval, estimation of measuring instrument reliability. The approach can be…

  15. Quantifying NUMA and Contention Effects in Multi-GPU Systems

    SciTech Connect

    Spafford, Kyle L; Meredith, Jeremy S; Vetter, Jeffrey S

    2011-01-01

    As system architects strive for increased density and power efficiency, the traditional compute node is being augmented with an increasing number of graphics processing units (GPUs). The integration of multiple GPUs per node introduces complex performance phenomena including non-uniform memory access (NUMA) and contention for shared system resources. Utilizing the Keeneland system, this paper quantifies these effects and presents some guidance on programming strategies to maximize performance in multi-GPU environments.

  16. Program partitioning for NUMA multiprocessor computer systems. [Nonuniform memory access

    SciTech Connect

    Wolski, R.M.; Feo, J.T. )

    1993-11-01

    Program partitioning and scheduling are essential steps in programming non-shared-memory computer systems. Partitioning is the separation of program operations into sequential tasks, and scheduling is the assignment of tasks to processors. To be effective, automatic methods require an accurate representation of the model of computation and the target architecture. Current partitioning methods assume today's most prevalent models -- macro dataflow and a homogeneous/two-level multicomputer system. Based on communication channels, neither model represents well the emerging class of NUMA multiprocessor computer systems consisting of hierarchical read/write memories. Consequently, the partitions generated by extant methods do not execute well on these systems. In this paper, the authors extend the conventional graph representation of the macro-dataflow model to enable mapping heuristics to consider the complex communication options supported by NUMA architectures. They describe two such heuristics. Simulated execution times of program graphs show that the model and heuristics generate higher quality program mappings than current methods for NUMA architectures.

  17. NuMA Influences Higher Order Chromatin Organization in Human Mammary Epithelium

    PubMed Central

    Abad, Patricia C.; Lewis, Jason; Mian, I. Saira; Knowles, David W.; Sturgis, Jennifer; Badve, Sunil; Xie, Jun

    2007-01-01

    The coiled-coil protein NuMA is an important contributor to mitotic spindle formation and stabilization. A potential role for NuMA in nuclear organization or gene regulation is suggested by the observations that its pattern of nuclear distribution depends upon cell phenotype and that it interacts and/or colocalizes with transcription factors. To date, the precise contribution of NuMA to nuclear function remains unclear. Previously, we observed that antibody-induced alteration of NuMA distribution in growth-arrested and differentiated mammary epithelial structures (acini) in three-dimensional culture triggers the loss of acinar differentiation. Here, we show that in mammary epithelial cells, NuMA is present in both the nuclear matrix and chromatin compartments. Expression of a portion of the C terminus of NuMA that shares sequence similarity with the chromatin regulator HPC2 is sufficient to inhibit acinar differentiation and results in the redistribution of NuMA, chromatin markers acetyl-H4 and H4K20m, and regions of deoxyribonuclease I-sensitive chromatin compared with control cells. Short-term alteration of NuMA distribution with anti-NuMA C-terminus antibodies in live acinar cells indicates that changes in NuMA and chromatin organization precede loss of acinar differentiation. These findings suggest that NuMA has a role in mammary epithelial differentiation by influencing the organization of chromatin. PMID:17108325

  18. Noninvasive assessment of alcoholic liver disease using unidimensional transient elastography (Fibroscan(®)).

    PubMed

    Lupsor-Platon, Monica; Badea, Radu

    2015-11-14

    Unidimensional transient elastography (TE) is a noninvasive technique, which has been increasingly used in the assessment of diffuse liver diseases. This paper focuses on reviewing the existing data on the use of TE in the diagnosis of fibrosis and in monitoring disease progression in alcoholic liver disease, on the factors that may influence the result of fibrosis prediction, and last but not least, on its potential use in assessing the steatosis degree. Therefore, this field is far from being exhausted and deserves more attention. Further studies are required, on large groups of biopsied patients, in order to find answers to all the remaining questions in this field. PMID:26576080

  19. Noninvasive assessment of alcoholic liver disease using unidimensional transient elastography (Fibroscan®)

    PubMed Central

    Lupsor-Platon, Monica; Badea, Radu

    2015-01-01

    Unidimensional transient elastography (TE) is a noninvasive technique, which has been increasingly used in the assessment of diffuse liver diseases. This paper focuses on reviewing the existing data on the use of TE in the diagnosis of fibrosis and in monitoring disease progression in alcoholic liver disease, on the factors that may influence the result of fibrosis prediction, and last but not least, on its potential use in assessing the steatosis degree. Therefore, this field is far from being exhausted and deserves more attention. Further studies are required, on large groups of biopsied patients, in order to find answers to all the remaining questions in this field. PMID:26576080

  20. Redistribution of the nuclear mitotic apparatus protein (NuMA) during mitosis and nuclear assembly. Properties of purified NuMA protein.

    PubMed

    Price, C M; Pettijohn, D E

    1986-10-01

    Monoclonal antibodies and human autoimmune sera specific for the nuclear mitotic apparatus protein (NuMA protein) were applied to study the structure of this protein and its intracellular distribution. The NuMA protein was purified using immuno-affinity columns. Studies on this large (250 kD) nuclear protein indicated that it is a highly asymmetric phosphoprotein. It is present in all mammalian cells examined and in those of some non-mammals. Immunofluorescence studies on fixed cells demonstrated that its intracellular distribution is essentially the same in all species at all stages of the cell cycle. Immunoblot (western blot) analysis showed that the size of the NuMA protein varies slightly in different species. At the onset of mitosis the NuMA protein redistributes from the nucleus to two centrosomal structures that later will become part of the mitotic spindle pole. This occurs at the time of nuclear breakdown and eventually leads to an accumulation of the NuMA protein at the polar region of the mitotic spindle. After anaphase the protein redistributes from the spindle polar region into the reforming nucleus and concentrates initially at the site where nuclear lamins and perichomatin have been reported to assemble. Living cells microinjected with fluorescent anti-NuMA antibodies were studied to examine parameters that effect the redistribution of the NuMA protein in vivo. These experiments indicate that microtubule assembly is essential for the NuMA protein to accumulate in the polar region. PMID:3527729

  1. Cell cycle-dependent SUMO-1 conjugation to nuclear mitotic apparatus protein (NuMA)

    SciTech Connect

    Seo, Jae Sung; Kim, Ha Na; Kim, Sun-Jick; Bang, Jiyoung; Kim, Eun-A; Sung, Ki Sa; Yoon, Hyun-Joo; Yoo, Hae Yong; Choi, Cheol Yong

    2014-01-03

    Highlights: •NuMA is modified by SUMO-1 in a cell cycle-dependent manner. •NuMA lysine 1766 is the primary target site for SUMOylation. •SUMOylation-deficient NuMA induces multiple spindle poles during mitosis. •SUMOylated NuMA induces microtubule bundling. -- Abstract: Covalent conjugation of proteins with small ubiquitin-like modifier 1 (SUMO-1) plays a critical role in a variety of cellular functions including cell cycle control, replication, and transcriptional regulation. Nuclear mitotic apparatus protein (NuMA) localizes to spindle poles during mitosis, and is an essential component in the formation and maintenance of mitotic spindle poles. Here we show that NuMA is a target for covalent conjugation to SUMO-1. We find that the lysine 1766 residue is the primary NuMA acceptor site for SUMO-1 conjugation. Interestingly, SUMO modification of endogenous NuMA occurs at the entry into mitosis and this modification is reversed after exiting from mitosis. Knockdown of Ubc9 or forced expression of SENP1 results in impairment of the localization of NuMA to mitotic spindle poles during mitosis. The SUMOylation-deficient NuMA mutant is defective in microtubule bundling, and multiple spindles are induced during mitosis. The mitosis-dependent dynamic SUMO-1 modification of NuMA might contribute to NuMA-mediated formation and maintenance of mitotic spindle poles during mitosis.

  2. Cell cycle-regulated membrane binding of NuMA contributes to efficient anaphase chromosome separation.

    PubMed

    Zheng, Zhen; Wan, Qingwen; Meixiong, Gerry; Du, Quansheng

    2014-03-01

    Accurate and efficient separation of sister chromatids during anaphase is critical for faithful cell division. It has been proposed that cortical dynein-generated pulling forces on astral microtubules contribute to anaphase spindle elongation and chromosome separation. In mammalian cells, however, definitive evidence for the involvement of cortical dynein in chromosome separation is missing. It is believed that dynein is recruited and anchored at the cell cortex during mitosis by the α subunit of heterotrimeric G protein (Gα)/mammalian homologue of Drosophila Partner of Inscuteable/nuclear mitotic apparatus (NuMA) ternary complex. Here we uncover a Gα/LGN-independent lipid- and membrane-binding domain at the C-terminus of NuMA. We show that the membrane binding of NuMA is cell cycle regulated-it is inhibited during prophase and metaphase by cyclin-dependent kinase 1 (CDK1)-mediated phosphorylation and only occurs after anaphase onset when CDK1 activity is down-regulated. Further studies indicate that cell cycle-regulated membrane association of NuMA underlies anaphase-specific enhancement of cortical NuMA and dynein. By replacing endogenous NuMA with membrane-binding-deficient NuMA, we can specifically reduce the cortical accumulation of NuMA and dynein during anaphase and demonstrate that cortical NuMA and dynein contribute to efficient chromosome separation in mammalian cells. PMID:24371089

  3. Perhaps Unidimensional Is Not Unidimensional

    ERIC Educational Resources Information Center

    Dodds, Pennie; Rae, Babette; Brown, Scott

    2012-01-01

    Miller (1956) identified his famous limit of 7 plus or minus 2 items based in part on absolute identification--the ability to identify stimuli that differ on a single physical dimension, such as lines of different length. An important aspect of this limit is its independence from perceptual effects and its application across all stimulus types.…

  4. Assessing item fit for unidimensional item response theory models using residuals from estimated item response functions.

    PubMed

    Haberman, Shelby J; Sinharay, Sandip; Chon, Kyong Hee

    2013-07-01

    Residual analysis (e.g. Hambleton & Swaminathan, Item response theory: principles and applications, Kluwer Academic, Boston, 1985; Hambleton, Swaminathan, & Rogers, Fundamentals of item response theory, Sage, Newbury Park, 1991) is a popular method to assess fit of item response theory (IRT) models. We suggest a form of residual analysis that may be applied to assess item fit for unidimensional IRT models. The residual analysis consists of a comparison of the maximum-likelihood estimate of the item characteristic curve with an alternative ratio estimate of the item characteristic curve. The large sample distribution of the residual is proved to be standardized normal when the IRT model fits the data. We compare the performance of our suggested residual to the standardized residual of Hambleton et al. (Fundamentals of item response theory, Sage, Newbury Park, 1991) in a detailed simulation study. We then calculate our suggested residuals using data from an operational test. The residuals appear to be useful in assessing the item fit for unidimensional IRT models. PMID:25106393

  5. NuMA Is Required for the Selective Induction of p53 Target Genes

    PubMed Central

    Ohata, Hirokazu; Miyazaki, Makoto; Otomo, Ryo; Matsushima-Hibiya, Yuko; Otsubo, Chihiro; Nagase, Takahiro; Arakawa, Hirofumi; Yokota, Jun; Nakagama, Hitoshi

    2013-01-01

    The p53 tumor suppressor protein is a transcription factor controlling various outcomes, such as growth arrest and apoptosis, through the regulation of different sets of target genes. The nuclear mitotic apparatus protein (NuMA) plays important roles in spindle pole organization during mitosis and in chromatin regulation in the nucleus during interphase. Although NuMA has been shown to colocalize with several nuclear proteins, including high-mobility-group proteins I and Y and GAS41, the role of NuMA during interphase remains unclear. Here we report that NuMA binds to p53 to modulate p53-mediated transcription. Acute and partial ablation of NuMA attenuates the induction of the proarrested p21 gene following DNA damage, subsequently causing impaired cell cycle arrest. Interestingly, NuMA knockdown had little effect on the induction of the p53-dependent proapoptotic PUMA gene. Furthermore, NuMA is required for the recruitment of cyclin-dependent kinase 8 (Cdk8), a component of the Mediator complex and a promoter of p53-mediated p21 gene function. These data demonstrate that NuMA is critical for the target selectivity of p53-mediated transcription. PMID:23589328

  6. An IRT Approach to Constructing and Scoring Pairwise Preference Items Involving Stimuli on Different Dimensions: The Multi-Unidimensional Pairwise-Preference Model

    ERIC Educational Resources Information Center

    Stark, Stephen; Chernyshenko, Oleksandr S.; Drasgow, Fritz

    2005-01-01

    This article proposes an item response theory (IRT) approach to constructing and scoring multidimensional pairwise preference items. Individual statements are administered and calibrated using a unidimensional single-stimulus model. Tests are created by combining multidimensional items with a small number of unidimensional pairings needed to…

  7. A Comparison of Estimation Methods for a Multi-unidimensional Graded Response IRT Model

    PubMed Central

    Kuo, Tzu-Chun; Sheng, Yanyan

    2016-01-01

    This study compared several parameter estimation methods for multi-unidimensional graded response models using their corresponding statistical software programs and packages. Specifically, we compared two marginal maximum likelihood (MML) approaches (Bock-Aitkin expectation-maximum algorithm, adaptive quadrature approach), four fully Bayesian algorithms (Gibbs sampling, Metropolis-Hastings, Hastings-within-Gibbs, blocked Metropolis), and the Metropolis-Hastings Robbins-Monro (MHRM) algorithm via the use of IRTPRO, BMIRT, and MATLAB. Simulation results suggested that, when the intertrait correlation was low, these estimation methods provided similar results. However, if the dimensions were moderately or highly correlated, Hastings-within-Gibbs had an overall better parameter recovery of item discrimination and intertrait correlation parameters. The performances of these estimation methods with different sample sizes and test lengths are also discussed. PMID:27375545

  8. Saltatory conduction revealed by unidimensional latency-topography of peripheral nerve impulse.

    PubMed

    Homma, S; Mizote, M; Nakajima, Y

    1983-09-01

    The ventral or dorsal root of the rat was placed on 12 electrodes arranged side by side at 0.4 mm intervals. Impulse conduction along the fiber was displayed using unidimensional latency-topography, which corresponds to the relation between latency and electrode distance. The relation revealed step-like displacement, which implies saltatory conduction of the impulse. Since the distance between the plateaux correspond to internodal length, the conduction velocity could be calculated from the length and the time differences between plateaux. It was found from 36 observations that : (i) mean internodal length was 0.92 +/- 0.13 mm (range 0.70--1.25 mm); (ii) mean conduction velocity was 76.1 +/- 20.7 m/s; and (iii) the correlation coefficient of conduction velocity and internodal length was statistically significant at r = 0.38 (P less than 0.025), so the longer the internodal length, the higher the conduction velocity. PMID:6633955

  9. A Comparison of Estimation Methods for a Multi-unidimensional Graded Response IRT Model.

    PubMed

    Kuo, Tzu-Chun; Sheng, Yanyan

    2016-01-01

    This study compared several parameter estimation methods for multi-unidimensional graded response models using their corresponding statistical software programs and packages. Specifically, we compared two marginal maximum likelihood (MML) approaches (Bock-Aitkin expectation-maximum algorithm, adaptive quadrature approach), four fully Bayesian algorithms (Gibbs sampling, Metropolis-Hastings, Hastings-within-Gibbs, blocked Metropolis), and the Metropolis-Hastings Robbins-Monro (MHRM) algorithm via the use of IRTPRO, BMIRT, and MATLAB. Simulation results suggested that, when the intertrait correlation was low, these estimation methods provided similar results. However, if the dimensions were moderately or highly correlated, Hastings-within-Gibbs had an overall better parameter recovery of item discrimination and intertrait correlation parameters. The performances of these estimation methods with different sample sizes and test lengths are also discussed. PMID:27375545

  10. The Unidimensional Relationship Closeness Scale (URCS): Reliability and Validity Evidence for a New Measure of Relationship Closeness

    ERIC Educational Resources Information Center

    Dibble, Jayson L.; Levine, Timothy R.; Park, Hee Sun

    2012-01-01

    A fundamental dimension along which all social and personal relationships vary is closeness. The Unidimensional Relationship Closeness Scale (URCS) is a 12-item self-report scale measuring the closeness of social and personal relationships. The reliability and validity of the URCS were assessed with college dating couples (N = 192), female friends…

  11. The Effect of Fitting a Unidimensional IRT Model to Multidimensional Data in Content-Balanced Computerized Adaptive Testing

    ERIC Educational Resources Information Center

    Song, Tian

    2010-01-01

    This study investigates the effect of fitting a unidimensional IRT model to multidimensional data in content-balanced computerized adaptive testing (CAT). Unconstrained CAT with the maximum information item selection method is chosen as the baseline, and the performances of three content balancing procedures, the constrained CAT (CCAT), the…

  12. NuMA localization, stability, and function in spindle orientation involve 4.1 and Cdk1 interactions

    PubMed Central

    Seldin, Lindsey; Poulson, Nicholas D.; Foote, Henry P.; Lechler, Terry

    2013-01-01

    The epidermis is a multilayered epithelium that requires asymmetric divisions for stratification. A conserved cortical protein complex, including LGN, nuclear mitotic apparatus (NuMA), and dynein/dynactin, plays a key role in establishing proper spindle orientation during asymmetric divisions. The requirements for the cortical recruitment of these proteins, however, remain unclear. In this work, we show that NuMA is required to recruit dynactin to the cell cortex of keratinocytes. NuMA's cortical recruitment requires LGN; however, LGN interactions are not sufficient for this localization. Using fluorescence recovery after photobleaching, we find that the 4.1-binding domain of NuMA is important for stabilizing its interaction with the cell cortex. This is functionally important, as loss of 4.1/NuMA interaction results in spindle orientation defects, using two distinct assays. Furthermore, we observe an increase in cortical NuMA localization as cells enter anaphase. Inhibition of Cdk1 or mutation of a single residue in NuMA mimics this effect. NuMA's anaphase localization is independent of LGN and 4.1 interactions, revealing two distinct mechanisms responsible for NuMA cortical recruitment at different stages of mitosis. This work highlights the complexity of NuMA localization and reveals the importance of NuMA cortical stability for productive force generation during spindle orientation. PMID:24109598

  13. NuMA Phosphorylation by Aurora-A Orchestrates Spindle Orientation.

    PubMed

    Gallini, Sara; Carminati, Manuel; De Mattia, Fabiola; Pirovano, Laura; Martini, Emanuele; Oldani, Amanda; Asteriti, Italia Anna; Guarguaglini, Giulia; Mapelli, Marina

    2016-02-22

    Spindle positioning is essential for tissue morphogenesis and homeostasis. The signaling network synchronizing spindle placement with mitotic progression relies on timely recruitment at the cell cortex of NuMA:LGN:Gαi complexes, in which NuMA acts as a receptor for the microtubule motor Dynein. To study the implication of Aurora-A in spindle orientation, we developed protocols for the partial inhibition of its activity. Under these conditions, in metaphase NuMA and Dynein accumulate abnormally at the spindle poles and do not reach the cortex, while the cortical distribution of LGN remains unperturbed. FRAP experiments revealed that Aurora-A governs the dynamic exchange between the cytoplasmic and the spindle pole-localized pools of NuMA. We show that Aurora-A phosphorylates directly the C terminus of NuMA on three Ser residues, of which Ser1969 determines the dynamic behavior and the spindle orientation functions of NuMA. Most interestingly, we identify a new microtubule-binding domain of NuMA, which does not overlap with the LGN-binding motif. Our study demonstrates that in metaphase the direct phosphorylation of NuMA by Aurora-A controls its cortical enrichment, and that this is the major event underlying the spindle orientation functions of Aurora-A in transformed and non-transformed cells in culture. Phosphorylation of NuMA by Aurora-A does not affect its affinity for microtubules or for LGN but rather determines the mobility of the protein at the spindle poles. The finding that NuMA can associate concomitantly with LGN and microtubules suggests that its microtubule-binding activity contributes to anchor Dynein-loaded microtubule +TIPs at cortical sites with LGN. PMID:26832443

  14. Memphis: Finding and Fixing NUMA-related Performance Problems on Multi-core Platforms

    SciTech Connect

    McCurdy, Collin B; Vetter, Jeffrey S

    2010-01-01

    Until recently, most high-end scientific applications have been immune to performance problems caused by Non-Uniform Memory Access (NUMA). However, current trends in micro-processor design are pushing NUMA to smaller and smaller scales. This paper examines the current state of NUMA and makes several contributions. First, we summarize the performance problems that NUMA can present for multithreaded applications and describe methods of addressing them. Second, we demonstrate that NUMA can indeed be a significant problem for scientific applications, showing that it can mean the difference between an application scaling perfectly and failing to scale at all. Third, we describe, in increasing order of usefulness, three methods of using hardware performance counters to aid in finding NUMA-related problems. Finally, we introduce Memphis, a data-centric toolset that uses Instruction Based Sampling to help pinpoint problematic memory accesses, and demonstrate how we used it to improve the performance of several production-level codes - HYCOM, XGC1 and CAM - by 13%, 23% and 24% respectively.

  15. Program partitioning and scheduling for NUMA computer architectures

    SciTech Connect

    Wolski, R.M.

    1994-03-01

    To effect the parallel execution of a program on a multiprocessor, each of the program`s constituent computations must be assigned to a processing resource within the multiprocessor. The problem of making this assignment so that execution time is minimized (known as the mapping problem) has been shown to be NP-complete. However, heuristics based on the performance characteristics of the target multiprocessor can yield execution times that approach the minimum possible. The mapping problem can be divided in to the problem of partitioning the computations into sequential threads, and the problem of scheduling those threads on the processors of the target system. This dissertation presents a logical framework and a set of heuristics that operate within the framework for the automatic partitioning and scheduling of programs at compile-time. The framework is based on the memory-node execution model which correctly captures the interaction between computations, processors, and the communication resources within a multiprocessor. The CP and HEF heuristics manipulate the features of the memory-node model to produce efficient program mappings. The effectiveness of the partitioning and scheduling techniques is investigated for Non-uniform Memory Access (NUMA) architecture types. To test the versatility of the approach, results are presented both for processors implementing strict execution semantics, and non-strict load/store semantics popular with RISC systems. The partitioner and scheduler are also used to investigate the possible advantages of multithreading (using either hardware or software), and the effectiveness of massively parallel systems, within a scientific programming context.

  16. Unidimensional Measurement May Evaluate Target Lymph Nodal Response After Induction Chemotherapy for Nasopharyngeal Carcinoma

    PubMed Central

    Chen, Chuanben; Zhang, Mingwei; Xu, Yuanji; Yue, Qiuyuan; Bai, Penggang; Zhou, Lin; Xiao, Youping; Zheng, Dechun; Lin, Kongqi; Qiu, Sufang; Chen, Yunbin; Pan, Jianji

    2016-01-01

    Abstract The aim of the study was to evaluate whether short axis and long axis on axial and coronal magnetic resonance imaging planes would reflect the tumor burden or alteration in size after induction chemotherapy in nasopharyngeal carcinoma. Patients with pathologically confirmed nasopharyngeal carcinoma (n = 37) with at least 1 positive cervical lymph node (axial short axis ≥15 mm) were consecutively enrolled in this prospective study. Lymph nodal measurements were performed along its short axis and long axis in both axial and coronal magnetic resonance imaging planes at diagnosis and after 2 cycles of induction chemotherapy. In addition, lymph nodal volumes were automatically calculated in 3D treatment-planning system, which were used as reference standard. Student's t test or nonparametric Mann–Whitney U test was used to compare the continuous quantitative variables. Meanwhile, the κ statistic and McNemar's test were used to evaluate the degree of agreement and discordance in response categorization among different measurements. Axial short axis was significantly associated with volumes at diagnosis (P < 0.001). A good agreement (κ=0.583) was found between axial short axis and volumetric criteria. However, the inconsistent lymph nodal shrinkage in 4 directions was observed. Axial short-axis shrinking was more rapid than the other 3 parameters. Interestingly, when utilizing the alternative planes for unidimensional measurements to assess tumor response, coronal short-axis showed the best concordance (κ=0.792) to the volumes. Axial short axis may effectively reflect tumor burden or change in tumor size in the assessment of target lymph nodal response after induction chemotherapy for nasopharyngeal carcinoma. However, it should be noted that axial short axis may amplify the therapeutic response. In addition, the role of coronal short axis in the assessment of tumor response needs further evaluation. PMID:26945354

  17. Prevendo a atividade solar através de redes neurais nebulosas

    NASA Astrophysics Data System (ADS)

    Martin, V. A. F.; Poppe, P. C. R.

    2003-08-01

    Atualmente, a integração de redes neurais com técnicas da Matemática Nebulosa (Fuzzy Sets), tem sido usada robustamente para fazer previsões em vários sistemas físicos. Este trabalho representa uma continuidade da contribuição apresentada anteriormente durante a XXVIIa Reunião Anual da SAB, onde exploramos a aplicação de redes neurais para previsões futuras de séries temporais. Para este, enfatizamos o uso da técnica ANFIS (Adaptative Neuro-Fuzzy Inference System), que consiste em uma rede do tipo back-propagation, onde os dados são processados em uma camada intermediária, tendo numa camada de saída, os dados numéricos. Para que a previsão seja feita com sucesso utilizando-se técnicas matemáticas adequadas, é fundamental a existência de uma série razoavelmente longa de modo que a dinâmica contida nesta possa ser melhor extraída pela rede neural. Nesse sentido, foram utilizados novamente os dados históricos das manchas do Sol (1818-2002) afim de verificar o comportamento futuro da atividade solar (Ciclos de Schawbe) a partir da técnica descrita acima. Previsões realizadas para o ciclo anterior (n.22, máximo de 158,5 em julho de 1989), bem como para o atual (n.23, máximo de 153 em setembro de 2000), apontam valores bastante coerentes com os publicados na literatura, levando em consideração, respectivamente, as barras de erros associadas: 166+/-18 e 160+/-14. Para o próximo ciclo de Schawbe (2006-2017), nossa previsão aponta o valor de 172+/-23 como máximo para o primeiro semestre de 2011 (Abril +/- 3 meses). A ANFIS acompanha de maneira satisfatória o movimento das séries estudadas durante o treinamento e durante a verificação (menor dispersão das funções de pertinência), com erro absoluto inferior a 20 por cento.

  18. Interaction between RB protein and NuMA is required for proper alignment of spindle microtubules.

    PubMed

    Uchida, Chiharu; Hattori, Takayuki; Takahashi, Hirotaka; Yamamoto, Naoki; Kitagawa, Masatoshi; Taya, Yoichi

    2014-02-01

    Retinoblastoma protein (pRB) controls cell cycle progression and cell cycle exit through interactions with cellular proteins. Many pRB-binding proteins, which function in gene transcription or modulation of chromatin structure, harbor LXCXE motifs in their binding domain for pRB. In this study, we found that nuclear mitotic apparatus protein (NuMA), a mitotic spindle organizer, interacts with pRB through LSCEE sequences located in its C-terminal region. siRNA-mediated down-regulation of pRB caused aberrant distribution of NuMA and alignment of spindle microtubules in mitotic cells. Abnormal organization of spindle microtubules was also accompanied by misalignment of an over-expressed NuMA mutant (mut-NuMA) with a defect in pRB binding caused by an LSGEK mutation. The mut-NuMA-over-expressing cells showed lower potency for survival than wild-type NuMA (wt-NuMA)-over-expressing cells during 2 weeks of culture. Interestingly, knockdown of pRB reduced the population of wt-NuMA-over-expressing cells to the same level as mut-NuMA cells after 2 weeks. Taken together, pRB may have a novel function in regulating the mitotic function of NuMA and spindle organization, which are required for proper cell cycle progression. PMID:24350565

  19. Exact solution of the unidimensional Poisson-Boltzmann equation for a 1:2 (2:1) electrolyte.

    PubMed Central

    Andrietti, F; Peres, A; Pezzotta, R

    1976-01-01

    The unidimensional Poisson-Boltzmann equation for a 1:2 (2:1) electrolyte has been solved analytically. The results have been compared with those obtained from the linearized equation. It is shown that in physiological conditions the difference may be greater than 10%. The value of the derivative of the potential in x=0, (dpsi/dx)x=0, has been used by many authors in the evaluation of the superficial charges of biological membranes. The value of (dpsi/dx)x-0 have also been compared with the ones derived from the linearized equation. The difference may be greater than 25%. Our results suggest that the linearization of the Poisson-Boltzmann equation for a 1:2(2:1) electrolyte may be greatly misleading. PMID:963209

  20. Developments in REDES: The rocket engine design expert system

    NASA Technical Reports Server (NTRS)

    Davidian, Kenneth O.

    1990-01-01

    The Rocket Engine Design Expert System (REDES) is being developed at the NASA-Lewis to collect, automate, and perpetuate the existing expertise of performing a comprehensive rocket engine analysis and design. Currently, REDES uses the rigorous JANNAF methodology to analyze the performance of the thrust chamber and perform computational studies of liquid rocket engine problems. The following computer codes were included in REDES: a gas properties program named GASP, a nozzle design program named RAO, a regenerative cooling channel performance evaluation code named RTE, and the JANNAF standard liquid rocket engine performance prediction code TDK (including performance evaluation modules ODE, ODK, TDE, TDK, and BLM). Computational analyses are being conducted by REDES to provide solutions to liquid rocket engine thrust chamber problems. REDES is built in the Knowledge Engineering Environment (KEE) expert system shell and runs on a Sun 4/110 computer.

  1. Developments in REDES: The Rocket Engine Design Expert System

    NASA Technical Reports Server (NTRS)

    Davidian, Kenneth O.

    1990-01-01

    The Rocket Engine Design Expert System (REDES) was developed at NASA-Lewis to collect, automate, and perpetuate the existing expertise of performing a comprehensive rocket engine analysis and design. Currently, REDES uses the rigorous JANNAF methodology to analyze the performance of the thrust chamber and perform computational studies of liquid rocket engine problems. The following computer codes were included in REDES: a gas properties program named GASP; a nozzle design program named RAO; a regenerative cooling channel performance evaluation code named RTE; and the JANNAF standard liquid rocket engine performance prediction code TDK (including performance evaluation modules ODE, ODK, TDE, TDK, and BLM). Computational analyses are being conducted by REDES to provide solutions to liquid rocket engine thrust chamber problems. REDES was built in the Knowledge Engineering Environment (KEE) expert system shell and runs on a Sun 4/110 computer.

  2. A Nonerythroid Isoform of Protein 4.1R Interacts with the Nuclear Mitotic Apparatus (NuMA) Protein

    PubMed Central

    Mattagajasingh, Subhendra N.; Huang, Shu-Ching; Hartenstein, Julia S.; Snyder, Michael; Marchesi, Vincent T.; Benz, Edward J.

    1999-01-01

    Red blood cell protein 4.1 (4.1R) is an 80- kD erythrocyte phosphoprotein that stabilizes the spectrin/actin cytoskeleton. In nonerythroid cells, multiple 4.1R isoforms arise from a single gene by alternative splicing and predominantly code for a 135-kD isoform. This isoform contains a 209 amino acid extension at its NH2 terminus (head piece; HP). Immunoreactive epitopes specific for HP have been detected within the cell nucleus, nuclear matrix, centrosomes, and parts of the mitotic apparatus in dividing cells. Using a yeast two-hybrid system, in vitro binding assays, coimmunolocalization, and coimmunoprecipitation studies, we show that a 135-kD 4.1R isoform specifically interacts with the nuclear mitotic apparatus (NuMA) protein. NuMA and 4.1R partially colocalize in the interphase nucleus of MDCK cells and redistribute to the spindle poles early in mitosis. Protein 4.1R associates with NuMA in the interphase nucleus and forms a complex with spindle pole organizing proteins, NuMA, dynein, and dynactin during cell division. Overexpression of a 135-kD isoform of 4.1R alters the normal distribution of NuMA in the interphase nucleus. The minimal sequence sufficient for this interaction has been mapped to the amino acids encoded by exons 20 and 21 of 4.1R and residues 1788–1810 of NuMA. Our results not only suggest that 4.1R could, possibly, play an important role in organizing the nuclear architecture, mitotic spindle, and spindle poles, but also could define a novel role for its 22–24-kD domain. PMID:10189366

  3. Converging Assessments of Unidimensionality.

    ERIC Educational Resources Information Center

    Tanaka, J. S.

    Using Goodman's (1975) notion of quasi-independence as a method of obtaining goodness of fit measures for non-scalable types in a scalogram analysis, archival data sets were examined using available Guttman scaling techniques, recent developments in latent structure analysis, and multidimensional scaling procedures. The Stouffer-Toby (1951) data…

  4. Parallel calculations on shared memory, NUMA-based computers using MATLAB

    NASA Astrophysics Data System (ADS)

    Krotkiewski, Marcin; Dabrowski, Marcin

    2014-05-01

    Achieving satisfactory computational performance in numerical simulations on modern computer architectures can be a complex task. Multi-core design makes it necessary to parallelize the code. Efficient parallelization on NUMA (Non-Uniform Memory Access) shared memory architectures necessitates explicit placement of the data in the memory close to the CPU that uses it. In addition, using more than 8 CPUs (~100 cores) requires a cluster solution of interconnected nodes, which involves (expensive) communication between the processors. It takes significant effort to overcome these challenges even when programming in low-level languages, which give the programmer full control over data placement and work distribution. Instead, many modelers use high-level tools such as MATLAB, which severely limit the optimization/tuning options available. Nonetheless, the advantage of programming simplicity and a large available code base can tip the scale in favor of MATLAB. We investigate whether MATLAB can be used for efficient, parallel computations on modern shared memory architectures. A common approach to performance optimization of MATLAB programs is to identify a bottleneck and migrate the corresponding code block to a MEX file implemented in, e.g. C. Instead, we aim at achieving a scalable parallel performance of MATLABs core functionality. Some of the MATLABs internal functions (e.g., bsxfun, sort, BLAS3, operations on vectors) are multi-threaded. Achieving high parallel efficiency of those may potentially improve the performance of significant portion of MATLABs code base. Since we do not have MATLABs source code, our performance tuning relies on the tools provided by the operating system alone. Most importantly, we use custom memory allocation routines, thread to CPU binding, and memory page migration. The performance tests are carried out on multi-socket shared memory systems (2- and 4-way Intel-based computers), as well as a Distributed Shared Memory machine with 96 CPU

  5. LAMTOR1-PRKCD and NUMA1-SFMBT1 fusion genes identified by RNA sequencing in aneurysmal benign fibrous histiocytoma with t(3;11)(p21;q13).

    PubMed

    Panagopoulos, Ioannis; Gorunova, Ludmila; Bjerkehagen, Bodil; Lobmaier, Ingvild; Heim, Sverre

    2015-11-01

    RNA sequencing of an aneurysmal benign fibrous histiocytoma with the karyotype 46,XY,t(3;11)(p21;q13),del(6)(p23)[17]/46,XY[2] showed that the t(3;11) generated two fusion genes: LAMTOR1-PRKCD and NUMA1-SFMBT1. RT-PCR together with Sanger sequencing verified the presence of fusion transcripts from both fusion genes. In the LAMTOR1-PRKCD fusion, the part of the PRKCD gene coding for the catalytic domain of the serine/threonine kinase is under control of the LAMTOR1 promoter. In the NUMA1-SFMBT1 fusion, the part of the SFMBT1 gene coding for two of four malignant brain tumor domains and the sterile alpha motif domain is controlled by the NUMA1 promoter. The data support a neoplastic genesis of aneurysmal benign fibrous histiocytoma and indicate a pathogenetic role for LAMTOR1-PRKCD and NUMA1-SFMBT1. PMID:26432191

  6. O Universo das Sociedades Numa Perspectiva Relativa: Exercícios de Etnoastronomia

    NASA Astrophysics Data System (ADS)

    Fares, Érika Akel; Pessoa Martins, Karla; Maciel Araujo, Lidiane; Sauma Filho, Michel

    2004-12-01

    This work developed at the Planetarium of Pará employing workshops designed for visitor schools (public, private, specials groups), promotes the popularization of the Ethnoastronomy with the aim of diffusing values based on a cultural diversity tolerance and the need of harmonic interplay between people and environment. Using stories and debates, the relationship between humans and the Cosmos is traced from antiquity until today, with the help of slides as a didactic resource. Thus, many conceptions about the origin of the Universe are shown; as well as some constellations created along the History, ending with the present scientific manner of know and explain the World. We then demonstrate the links between space, time and culture with the Cosmos vision. The need to think the World within a plural context to create respect for other different persons is emphasized. Este trabalho, desenvolvido no Planetário do Pará através de oficinas com escolas visitantes (públicas, privadas e grupos especiais), promove a popularização da Etnoastronomia, com o objetivo de difundir valores pautados na tolerância à diversidade cultural e na necessidade da convivência harmônica entre o ser humano e o meio ambiente. Através da contação de histórias e promoção de debate, é tratada a relação dos humanos com o céu desde a antiguidade até os dias atuais, tendo como apoio didático o uso de slides. Assim, são mostradas diversas concepções de origem do Universo; algumas constelações criadas no decorrer da História; e a atual forma científica de conhecer e explicar o mundo. Demonstrando-se, então, a interligação entre espaço, tempo e cultura com a visão do Cosmo. Enfatiza-se a necessidade de se pensar o mundo numa perspectiva relativa ou plural, de forma a propiciar o respeito ao ser diferente.

  7. Modeling and Testing Differential Item Functioning in Unidimensional Binary Item Response Models with a Single Continuous Covariate: A Functional Data Analysis Approach.

    PubMed

    Liu, Yang; Magnus, Brooke E; Thissen, David

    2016-06-01

    Differential item functioning (DIF), referring to between-group variation in item characteristics above and beyond the group-level disparity in the latent variable of interest, has long been regarded as an important item-level diagnostic. The presence of DIF impairs the fit of the single-group item response model being used, and calls for either model modification or item deletion in practice, depending on the mode of analysis. Methods for testing DIF with continuous covariates, rather than categorical grouping variables, have been developed; however, they are restrictive in parametric forms, and thus are not sufficiently flexible to describe complex interaction among latent variables and covariates. In the current study, we formulate the probability of endorsing each test item as a general bivariate function of a unidimensional latent trait and a single covariate, which is then approximated by a two-dimensional smoothing spline. The accuracy and precision of the proposed procedure is evaluated via Monte Carlo simulations. If anchor items are available, we proposed an extended model that simultaneously estimates item characteristic functions (ICFs) for anchor items, ICFs conditional on the covariate for non-anchor items, and the latent variable density conditional on the covariate-all using regression splines. A permutation DIF test is developed, and its performance is compared to the conventional parametric approach in a simulation study. We also illustrate the proposed semiparametric DIF testing procedure with an empirical example. PMID:26155757

  8. NuMA promotes homologous recombination repair by regulating the accumulation of the ISWI ATPase SNF2h at DNA breaks

    PubMed Central

    Vidi, Pierre-Alexandre; Liu, Jing; Salles, Daniela; Jayaraman, Swaathi; Dorfman, George; Gray, Matthew; Abad, Patricia; Moghe, Prabhas V.; Irudayaraj, Joseph M.; Wiesmüller, Lisa; Lelièvre, Sophie A.

    2014-01-01

    Chromatin remodeling factors play an active role in the DNA damage response by shaping chromatin to facilitate the repair process. The spatiotemporal regulation of these factors is key to their function, yet poorly understood. We report that the structural nuclear protein NuMA accumulates at sites of DNA damage in a poly[ADP-ribose]ylation-dependent manner and functionally interacts with the ISWI ATPase SNF2h/SMARCA5, a chromatin remodeler that facilitates DNA repair. NuMA coimmunoprecipitates with SNF2h, regulates its diffusion in the nucleoplasm and controls its accumulation at DNA breaks. Consistent with NuMA enabling SNF2h function, cells with silenced NuMA exhibit reduced chromatin decompaction after DNA cleavage, lesser focal recruitment of homologous recombination repair factors, impaired DNA double-strand break repair in chromosomal (but not in episomal) contexts and increased sensitivity to DNA cross-linking agents. These findings reveal a structural basis for the orchestration of chromatin remodeling whereby a scaffold protein promotes genome maintenance by directing a remodeler to DNA breaks. PMID:24753406

  9. Redes En Acción. Increasing Hispanic participation in cancer research, training, and awareness.

    PubMed

    Ramirez, Amelie G; Talavera, Gregory A; Marti, Jose; Penedo, Frank J; Medrano, Martha A; Giachello, Aida L; Pérez-Stable, Eliseo J

    2006-10-15

    Hispanics are affected by many health care disparities. The National Cancer Institute (NCI), through its Special Populations Branch, is supporting networking and capacity-building activities designed to increase Hispanic participation and leadership in cancer research. Redes En Acción established a national network of cancer research centers, community-based organizations, and federal partners to facilitate opportunities for junior Hispanic scientists to participate in training and research projects on cancer control. Since 2000, Redes En Acción has established a network of more than 1800 Hispanic leaders involved in cancer research and education. The project has sustained 131 training positions and submitted 29 pilot projects to NCI for review, with 16 awards for a total of $800,000, plus an additional $8.8 million in competing grant funding based on pilot study results to date. Independent research has leveraged an additional $32 million in non-Redes funding, and together the national and regional network sites have participated in more than 1400 community and professional awareness events. In addition, the program conducted extensive national survey research that provided the basis for the Redes En Acción Latino Cancer Report, a national agenda on Hispanic cancer issues. Redes En Acción has increased participation in cancer control research, training, and awareness among Hispanic scientists and within Hispanic communities. Cancer 2006. (c) 2006 American Cancer Society. PMID:16958026

  10. Understanding Parameter Invariance in Unidimensional IRT Models

    ERIC Educational Resources Information Center

    Rupp, Andre A.; Zumbo, Bruno D.

    2006-01-01

    One theoretical feature that makes item response theory (IRT) models those of choice for many psychometric data analysts is parameter invariance, the equality of item and examinee parameters from different examinee populations or measurement conditions. In this article, using the well-known fact that item and examinee parameters are identical only…

  11. National Urbanization Monitoring Assessment (NUMA)

    USGS Publications Warehouse

    Hester, Dave

    2006-01-01

    A core geographic science element of the U.S. Geological Survey's Geographic Analysis and Monitoring (GAM) Program is to monitor land-surface change for the Nation through time. The Nation's land surface is dynamically evolving and transitioning in response to natural and human processes. The need to understand the transformations and locations where changes are taking place, their underlying causes, and the rate at which the transitions are occurring is fundamental to the health and viability of the Nation's natural and developed environments.

  12. Rainfall Erosivity Database on the European Scale (REDES): A product of a high temporal resolution rainfall data collection in Europe

    NASA Astrophysics Data System (ADS)

    Panagos, Panos; Ballabio, Cristiano; Borrelli, Pasquale; Meusburger, Katrin; Alewell, Christine

    2016-04-01

    The erosive force of rainfall is expressed as rainfall erosivity. Rainfall erosivity considers the rainfall amount and intensity, and is most commonly expressed as the R-factor in the (R)USLE model. The R-factor is calculated from a series of single storm events by multiplying the total storm kinetic energy with the measured maximum 30-minutes rainfall intensity. This estimation requests high temporal resolution (e.g. 30 minutes) rainfall data for sufficiently long time periods (i.e. 20 years) which are not readily available at European scale. The European Commission's Joint Research Centre(JRC) in collaboration with national/regional meteorological services and Environmental Institutions made an extensive data collection of high resolution rainfall data in the 28 Member States of the European Union plus Switzerland in order to estimate rainfall erosivity in Europe. This resulted in the Rainfall Erosivity Database on the European Scale (REDES) which included 1,541 rainfall stations in 2014 and has been updated with 134 additional stations in 2015. The interpolation of those point R-factor values with a Gaussian Process Regression (GPR) model has resulted in the first Rainfall Erosivity map of Europe (Science of the Total Environment, 511, 801-815). The intra-annual variability of rainfall erosivity is crucial for modelling soil erosion on a monthly and seasonal basis. The monthly feature of rainfall erosivity has been added in 2015 as an advancement of REDES and the respective mean annual R-factor map. Almost 19,000 monthly R-factor values of REDES contributed to the seasonal and monthly assessments of rainfall erosivity in Europe. According to the first results, more than 50% of the total rainfall erosivity in Europe takes place in the period from June to September. The spatial patterns of rainfall erosivity have significant differences between Northern and Southern Europe as summer is the most erosive period in Central and Northern Europe and autumn in the

  13. Estimativa de imagens solares soho através de redes neurais artificiais

    NASA Astrophysics Data System (ADS)

    Andrade, M. C.; Fernandes, F. C. R.; Cecatto, J. R.; Rios Neto, A.; Rosa, R. R.; Sawant, H. S.

    2003-08-01

    A Rede Neural Artificial (RNA), no âmbito da teoria computacional, constitui uma teoria emergente que, por possuir habilidade em aprender a partir de dados de entrada, encontra diferentes aplicações em diferentes áreas. Um exemplo é a utilização de RNA na caracterização de padrões associados à dinâmica de processos espaço-temporais relacionados a fenômenos físicos não-lineares. Para obter informações sobre o comportamento destes fenômenos físicos utiliza-se, em diversos casos, seqüências de imagens digitalizadas, onde a caracterização de alguns fenômenos espaço-temporais é o procedimento mais viável para descrever a dinâmica das regiões ativas do Sol. Com base em imagens observadas por telescópios a bordo de satélites, estudos de previsão de eventos solares podem ser programados, permitindo prever possíveis efeitos posteriores nas regiões mais próximas da Terra (tempestades geomagnéticas e irregularidades ionosféricas). Neste trabalho avaliamos o desempenho da RNA para estimar padrões espaço-temporais, ou seja, imagens solares em ultravioleta, obtidas através do telescópio a bordo do satélite SOHO. Os resultados mostraram que as RNA conseguem generalizar os padrões de maneira satisfatória sem perder de forma significativa os principais aspectos da configuração global da atmosfera solar, comprovando a eficácia da RNA como ferramenta para esse tipo de aplicação. Portanto, este trabalho comprova a viabilidade de uso desta ferramenta em projetos voltados ao estudo do comportamento solar, em trabalhos do grupo de Física do Meio Interplanetário (FMI) na DAS e em programas desenvolvidos pelo Núcleo de Simulação e Análise de Sistemas Complexos (NUSASC) do Laboratório Associado de Computação e Matemática Aplicada (LAC) do INPE.

  14. Unidimensional Scaling of Two Person Non-Zero Sum Games.

    ERIC Educational Resources Information Center

    Baerwaldt, James; Talley, Martha

    Groups of students were required to respond to the same eight two-person games, two variants each of four qualitatively different separable games including Prisoner's Dilemma. The games were generated by varying a payoff parameter which altered the potential maximum per trial difference between payoffs for the two players. The groups differed…

  15. Unidimensional thermal gradients Tn in a nanoscopic superconductor

    NASA Astrophysics Data System (ADS)

    Barba-Ortega, J.; Carrillo, H. M.; Sjogreen-Blanco, C. A.

    2016-06-01

    In general, few studies of the Abrikosov state in mesoscopic superconductors have been carried out with the presence of temperature gradients. We know that there can be situations where a sample near a heater source leads to a variable temperature system. Thus, in this work we studied the influence of several thermal gradients on the vortex configuration and the thermodynamics properties of a low critical temperature nanoscopic superconducting long square prism of size d × d. For this purposes, we simulated a hypothetical physical situation where the temperature varies into the sample as T =T1 +(x / d) n(T2 -T1) , with T =T1(x = 0) , T =T2(x = d) and n = 1 , 2 , 3 , 4 , 5 , 6 , T1 < T2. The field for the first vortex penetration H1 presents a slow dependence on n and d.

  16. Bias Coefficients for Lack of Invariance in Unidimensional IRT Models.

    ERIC Educational Resources Information Center

    Rupp, Andre A.; Zumbo, Bruno D.

    The feature that makes item response theory (IRT) models the models of choice for many psychometric data analysts is parameter invariance, the equality of item and examinee parameters from different populations. Using the well-known fact that item and examinee parameters are identical only up to a set of linear transformations specific to the…

  17. ALAM and ALAS: Questioning Error Assignments in Unidimensional Guttman Scaling

    ERIC Educational Resources Information Center

    Wimberley, Ronald C.

    1976-01-01

    When researchers use the Guttman scalogram rather than multidimensional techniques, scalogram error assignment techniques should be questioned. An alternative to the customary minimizing error rule is suggested through ALAM and ALAS criteria which use ordinal information in scalable item marginals. (Author)

  18. Quaternary glacial geomorphosites from the Cantabrian Mountains (northern Iberian Peninsula): the Redes Natural Reservation and Picos de Europa Regional Park

    NASA Astrophysics Data System (ADS)

    Rodríguez-Rodríguez, Laura; Jiménez-Sánchez, Montserrat; José Domínguez-Cuesta, María

    2013-04-01

    The Cantabrian Mountains is a mountain range 480 km-long and up to 2,648 m altitude (Torre Cerredo Peak) trending parallel to the Cantabrian Coastline between Pyrenees and the northwest corner of the Iberian Peninsula (~43oN 5oW). This mountain range is an outstanding area to research the climatic patterns across South Europe during the Quaternary glaciations since well-preserved glacial features evidence the occurrence of past mountain glaciations in a climatic environment marked by the transition from a maritime climate (Atlantic) to Mediterranean one across the mountain range. The available studies in the Cantabrian Mountains stand that the regional glacial maximum recorded here is prior to ca 38, and that glaciers were in some locations remarkably retreated by the time of the global Last Glacial Maximum (Jiménez-Sánchez et al., in press; Serrano et al., in press). This study is focused on an area about 800 km2 that includes 36 peaks over 2,000 m (Pico Mampodre; 2,192 m) and partially covers the Redes Natural Reservation and Picos de Europa Regional Park. A geomorphologic database in ArcGIS was produced for this area as a previous step to reconstruct in detail the extent, flow pattern and chronology of the former glaciers (PhD under progress). Here we present a selection of 18 glacial geomorphosites classified according to genetic criteria in sites that show: (i) a nicely preserved moraine sequence recording the transition from glacial to periglacial conditions; (ii) glacial erosion features; (iii) glacial and ice related deposits (like moraines, ice-dammed deposits, erratic boulders or fluvio-glacial deposits); (iv) slope instability related to glacial debuttressing (complex landslides and rock avalanches); and (v) the interaction between the landscape and human activity. The interest of the geomorphosites is supported by its good quality of preservation, allowing its use as a basis to reconstruct the glacial and paraglacial processes in this region during

  19. Percepção Astronômica de Alunos do Ensino Médio da Rede Estadual de São Paulo

    NASA Astrophysics Data System (ADS)

    de Oliveira, E. F.; Voelzke, M. R.; Amaral, L. H.

    2005-08-01

    Embora a astronomia seja uma das ciências mais antigas da humanidade e muitos dos conceitos astronômicos serem populares, principalmente nesta época de alta globalização do conhecimento por intermédio de eficientes meios de comunicação e de obtenção da informação, notadamente através da internet, observa-se que uma parcela significativa dos estudantes encontra-se à margem dessas informações. O presente trabalho visa analisar o nível de conhecimento básico dos alunos de Ensino Médio da rede estadual da cidade de Suzano quanto aos fenômenos astronômicos que os rodeiam, tais como a sucessão dos dias e das estações do ano, além de questioná-los sobre fatos genéricos tais como: quais são os astros que se encontram mais próximos do planeta Terra, o que vem a ser o Sol, o Big Bang, um ano-luz, uma estrela cadente, a estrela de Bélem e o que ocasionou a extinção dos dinossauros. Para tanto foi elaborado um formulário constando de questões de múltipla escolha, o qual foi aplicado no primeiro colegial noturno da Escola Estadual Batista Renzi. Num espaço amostral de 34 alunos constatou-se que apenas 29,4% compreendiam a sucessão dos dias da semana, que apenas 20,6% explicaram corretamente as estações do ano, que apenas 20,6% tinham idéia de quais são os objetos celestes mais próximos da Terra, em contraposição 67,6% sabiam classificar corretamente o Sol como estrela, 55,9% relacionavam o Big Bang à origem do universo, apenas 20,6% identificavam um ano-luz como unidade de distância, 32,4% reconheciam uma estrela cadente como meteoro, 41,2% consideravam a estrela de Belém como um cometa e 50,0% explicaram corretamente a extinção dos dinossauros. A presente análise será expandida para as demais classes de primeiro colegial, não somente do período noturno, mas também do diurno da Escola Estadual Batista Renzi, bem como o formulário será devidamente ampliado. Já nesta primeira fase nota-se claramente o pequeno discernimento

  20. Is patient satisfaction a unidimensional construct? Factor analysis of the Munich Patient Satisfaction Scale (MPSS-24).

    PubMed

    Möller-Leimkühler, Anne Marie; Dunkel, Ralf; Müller, Peter; Pukies, Guido; de Fazio, Sarino; Lehmann, Erlo

    2002-02-01

    Although patients' satisfaction with treatment has gained much attention, conceptual and methodological issues are not sufficiently investigated. Consequently, well-validated satisfaction scales are rare. In order to respond to methodological requirements being associated with the measurement of patient satisfaction, the Munich Patient Satisfaction Scale (MPSS-24) was developed for psychiatric in-patients. The scale was validated on the basis of three independent samples (n=85, n= 161, n=91), and the effects of moderating variables were controlled. In several steps of item selection the initial pool of 133 items was reduced to 24 items, which were subjected to factor analysis. The MPSS-24 demonstrates one major principal component with two minor factors which indicates that doctor-patient communication is the essential source for patient satisfaction. The instrument is of high internal consistency and reliability, and convergent validity is satisfactory. PMID:12056577

  1. A GPU-Based Gibbs Sampler for a Unidimensional IRT Model

    PubMed Central

    Welling, William S.; Zhu, Michelle M.

    2014-01-01

    Item response theory (IRT) is a popular approach used for addressing large-scale statistical problems in psychometrics as well as in other fields. The fully Bayesian approach for estimating IRT models is usually memory and computationally expensive due to the large number of iterations. This limits the use of the procedure in many applications. In an effort to overcome such restraint, previous studies focused on utilizing the message passing interface (MPI) in a distributed memory-based Linux cluster to achieve certain speedups. However, given the high data dependencies in a single Markov chain for IRT models, the communication overhead rapidly grows as the number of cluster nodes increases. This makes it difficult to further improve the performance under such a parallel framework. This study aims to tackle the problem using massive core-based graphic processing units (GPU), which is practical, cost-effective, and convenient in actual applications. The performance comparisons among serial CPU, MPI, and compute unified device architecture (CUDA) programs demonstrate that the CUDA GPU approach has many advantages over the CPU-based approach and therefore is preferred. PMID:27355058

  2. The Graded Unfolding Model: A Unidimensional Item Response Model for Unfolding Graded Responses.

    ERIC Educational Resources Information Center

    Roberts, James S.; Laughlin, James E.

    Binary or graded disagree-agree responses to attitude items are often collected for the purpose of attitude measurement. Although such data are sometimes analyzed with cumulative measurement models, recent investigations suggest that unfolding models are more appropriate (J. S. Roberts, 1995; W. H. Van Schuur and H. A. L. Kiers, 1994). Advances in…

  3. The Robustness of IRT-Based Vertical Scaling Methods to Violation of Unidimensionality

    ERIC Educational Resources Information Center

    Yin, Liqun

    2013-01-01

    In recent years, many states have adopted Item Response Theory (IRT) based vertically scaled tests due to their compelling features in a growth-based accountability context. However, selection of a practical and effective calibration/scaling method and proper understanding of issues with possible multidimensionality in the test data is critical to…

  4. Hierarchical diagnostic classification models morphing into unidimensional 'diagnostic' classification models-a commentary.

    PubMed

    von Davier, Matthias; Haberman, Shelby J

    2014-04-01

    This commentary addresses the modeling and final analytical path taken, as well as the terminology used, in the paper "Hierarchical diagnostic classification models: a family of models for estimating and testing attribute hierarchies" by Templin and Bradshaw (Psychometrika, doi: 10.1007/s11336-013-9362-0, 2013). It raises several issues concerning use of cognitive diagnostic models that either assume attribute hierarchies or assume a certain form of attribute interactions. The issues raised are illustrated with examples, and references are provided for further examination. PMID:24478022

  5. Limits on Log Odds Ratios for Unidimensional Item Response Theory Models

    ERIC Educational Resources Information Center

    Haberman, Shelby J.; Holland, Paul W.; Sinharay, Sandip

    2007-01-01

    Bounds are established for log odds ratios (log cross-product ratios) involving pairs of items for item response models. First, expressions for bounds on log odds ratios are provided for one-dimensional item response models in general. Then, explicit bounds are obtained for the Rasch model and the two-parameter logistic (2PL) model. Results are…

  6. Multidimensional Rule, Unidimensional Rule, and Similarity Strategies in Categorization: Event-Related Brain Potential Correlates

    ERIC Educational Resources Information Center

    Folstein, Jonathan R.; Van Petten, Cyma

    2004-01-01

    Forty participants assigned artificial creatures to categories after explicit rule instruction or feedback alone. Stimuli were typical and atypical exemplars of 2 categories with independent prototypes, conflicting exemplars sharing features of both categories, and "Others" with only 1 or 2 features of the well-defined categories. Ten…

  7. Psychometric Characteristics of Integrated Multi-Specialty Examinations: Ebel Ratings and Unidimensionality

    ERIC Educational Resources Information Center

    Homer, Matt; Darling, Jonathan; Pell, Godfrey

    2012-01-01

    Over recent years, UK medical schools have moved to more integrated summative examinations. This paper analyses data from the written assessment of undergraduate medical students to investigate two key psychometric aspects of this type of high-stakes assessment. Firstly, the strength of the relationship between examiner predictions of item…

  8. Between-Person and Within-Person Subscore Reliability: Comparison of Unidimensional and Multidimensional IRT Models

    ERIC Educational Resources Information Center

    Bulut, Okan

    2013-01-01

    The importance of subscores in educational and psychological assessments is undeniable. Subscores yield diagnostic information that can be used for determining how each examinee's abilities/skills vary over different content domains. One of the most common criticisms about reporting and using subscores is insufficient reliability of subscores.…

  9. Unidimensional versus Multidimensional Approaches to the Assessment of Acculturation for Asian American Populations.

    ERIC Educational Resources Information Center

    Abe-Kim, Jennifer; Okazaki, Sumie; Goto, Sharon G.

    2001-01-01

    Examines approaches to assessing acculturation among Asian Americans college students in relation to the cultural indicators of individualism-collectivism, self-construal, impression management, and loss of face. An uneven nature of these relationships was found which is significant in light of the fact that acculturation differences are often…

  10. An Algorithm for Testing Unidimensionality and Clustering Items in Rasch Measurement

    ERIC Educational Resources Information Center

    Debelak, Rudolf; Arendasy, Martin

    2012-01-01

    A new approach to identify item clusters fitting the Rasch model is described and evaluated using simulated and real data. The proposed method is based on hierarchical cluster analysis and constructs clusters of items that show a good fit to the Rasch model. It thus gives an estimate of the number of independent scales satisfying the postulates of…

  11. Unidimensional IRT Item Parameter Estimates across Equivalent Test Forms with Confounding Specifications within Dimensions

    ERIC Educational Resources Information Center

    Matlock, Ki Lynn; Turner, Ronna

    2016-01-01

    When constructing multiple test forms, the number of items and the total test difficulty are often equivalent. Not all test developers match the number of items and/or average item difficulty within subcontent areas. In this simulation study, six test forms were constructed having an equal number of items and average item difficulty overall.…

  12. Development of Depth Perception Mediated by Motion Parallax in Unidimensional Projections of Rotation in Depth.

    ERIC Educational Resources Information Center

    Carpenter, David L.

    1979-01-01

    Six motion projections were presented to first graders, seventh graders, and college students (N=72) in order to determine whether children can utilize the same motion parallax information as can adults. (MP)

  13. Applying Unidimensional and Multidimensional Item Response Theory Models in Testlet-Based Reading Assessment

    ERIC Educational Resources Information Center

    Min, Shangchao; He, Lianzhen

    2014-01-01

    This study examined the relative effectiveness of the multidimensional bi-factor model and multidimensional testlet response theory (TRT) model in accommodating local dependence in testlet-based reading assessment with both dichotomously and polytomously scored items. The data used were 14,089 test-takers' item-level responses to the…

  14. Bias of Exploratory and Cross-Validated DETECT Index under Unidimensionality

    ERIC Educational Resources Information Center

    Monahan, Patrick O.; Stump, Timothy E.; Finch, Holmes; Hambleton, Ronald K.

    2007-01-01

    DETECT is a nonparametric "full" dimensionality assessment procedure that clusters dichotomously scored items into dimensions and provides a DETECT index of magnitude of multidimensionality. Four factors (test length, sample size, item response theory [IRT] model, and DETECT index) were manipulated in a Monte Carlo study of bias, standard error,…

  15. The Analysis of Dominance Matrices: Extraction of Unidimensional Orders Within a Multidimensional Context. Technical Report No. 3.

    ERIC Educational Resources Information Center

    Reynolds, Thomas J.

    A method of factor extraction specific to a binary matrix, illustrated here as a person-by-item response matrix, is presented. The extraction procedure, termed ERGO, differs from the more commonly implemented dimensionalizing techniques, factor analysis and multidimensional scaling, by taking into consideration item difficulty. Utilized in the…

  16. A Comparison of Unidimensional and Three-Dimensional Differential Item Functioning Analysis Using Two-Dimensional Data

    ERIC Educational Resources Information Center

    Snow, Teresa K.; Oshima, T. C.

    2009-01-01

    Oshima, Raju, and Flowers demonstrated the use of an item response theory-based technique for analyzing differential item function (DIF) and differential test function for dichotomously scored data that are intended to be multidimensional. Their study assumed that the number of intended-to-be measured dimensions was correctly identified. In…

  17. Development of a Unidimensional Composite Measure of Neuropsychological Functioning in Older Cardiac Surgery Patients with Good Measurement Precision

    PubMed Central

    Jones, Richard N.; Rudolph, James L.; Inouye, Sharon K; Yang, Frances M.; Fong, Tamara G.; Milberg, William P.; Tommet, Douglas; Metzger, Eran D.; Cupples, L. Adrienne; Marcantonio, Edward R.

    2010-01-01

    The objective of this analysis was to develop a measure of neuropsychological performance for cardiac surgery and assess its psychometric properties. Older patients (n=210) underwent a neuropsychological battery using nine assessments. The number of factors was identified with variable reduction methods. Item response theory-based factor analysis methods were used to evaluate the measure. Modified parallel analysis supported a single factor, and the battery formed an internally consistent set (coefficient alpha=0.82). The developed measure provided a reliable, continuous measure (reliability >0.90) across a broad range of performance (−1.5 SD units to +1.0 SD units) with minimal ceiling and floor effects. PMID:20446144

  18. The Confounding Effects of Ability, Item Difficulty, and Content Balance within Multiple Dimensions on the Estimation of Unidimensional Thetas

    ERIC Educational Resources Information Center

    Matlock, Ki Lynn

    2013-01-01

    When test forms that have equal total test difficulty and number of items vary in difficulty and length within sub-content areas, an examinee's estimated score may vary across equivalent forms, depending on how well his or her true ability in each sub-content area aligns with the difficulty of items and number of items within these areas.…

  19. A Comparison of Item Parameter Standard Error Estimation Procedures for Unidimensional and Multidimensional Item Response Theory Modeling

    ERIC Educational Resources Information Center

    Paek, Insu; Cai, Li

    2014-01-01

    The present study was motivated by the recognition that standard errors (SEs) of item response theory (IRT) model parameters are often of immediate interest to practitioners and that there is currently a lack of comparative research on different SE (or error variance-covariance matrix) estimation procedures. The present study investigated item…

  20. Not All Same-Different Discriminations Are Created Equal: Evidence Contrary to a Unidimensional Account of Same-Different Learning

    ERIC Educational Resources Information Center

    Gibson, Brett M.; Wasserman, Edward A.; Cook, Robert G.

    2006-01-01

    In Experiment 1, we trained four pigeons to concurrently discriminate displays of 16 same icons (16S) from displays of 16 different icons (16D) as well as between displays of same icons (16S) from displays that contained 15 same icons and one different icon (15S:1D). The birds rapidly learned to discriminate 16S vs. 16D displays, but they failed…

  1. Continuum beliefs about psychotic symptoms are a valid, unidimensional construct: Construction and validation of a revised continuum beliefs questionnaire.

    PubMed

    Schlier, Björn; Scheunemann, Jakob; Lincoln, Tania M

    2016-07-30

    Growing evidence supports a continuum model of psychosis, with mild psychotic symptoms being frequently experienced by the general population. Moreover, believing in the continuum model correlates with less stigmatization of schizophrenia. This study explores whether continuum beliefs are a valid construct and develops a continuum beliefs scale. First, expert-generated items were reduced to a candidate scale (study 1, n=95). One-dimensionality was tested using confirmatory factor analysis (study 2, n=363). Convergent validity was tested with a previous continuum beliefs scale, essentialist beliefs, and stigmatization (study 2), while self-reported psychotic experiences (i.e. frequency and conviction) served to test discriminant validity (study 3, n=229). A nine item questionnaire that assesses continuum beliefs about schizophrenia symptoms showed acceptable to good psychometric values, high correlations with a previous continuum beliefs scale and small correlations with essentialist beliefs, stereotypes, and desired social distance. No correlations with psychotic experiences were found. Thus, continuum beliefs can be considered a valid construct. The construed CBQ-R asks about symptoms rather than the abstract category "schizophrenia", which may increase understandability of the scale. Validation confirms previous studies and highlights the difference between continuum beliefs and personal psychotic experiences. PMID:27175910

  2. NuMas: A LAN-based materials control and accounting system in production

    SciTech Connect

    Strickland, T.W.; Bracey, J.T.; McMahon, S.A.

    1995-12-31

    A state-of-the-art Nuclear Materials Control and Accounting (NMC and A) System has been implemented and is fully operational at the Paducah Gaseous Diffusion Plant (PGDP) as of September 1994. The uranium enrichment facility is currently regulated by the Department of Energy (DOE) and is in the process of obtaining Nuclear Regulatory Commission (NRC) certification. Implementation of this system has resulted in a tremendous cost savings to the facility as well as improvements to the overall efficiency of the NMC and A department. This paper outlines the benefits of implementing a Personal Computer/Local Area Network (PC/LAN)-based system in hopes of attracting other facilities to explore and utilize its application at their sites.

  3. Unidimensional Approximations for a Computerized Classification Test When the Item Pool and Latent Space Are Multidimensional. ACT Research Report Series 97-5.

    ERIC Educational Resources Information Center

    Spray, Judith A.; Abdel-fattah, Abdel-fattah A.; Huang, Chi-Yu; Lau, C. Allen

    The primary concern or focus of a certification or licensure test is to obtain valid criterion-referenced information regarding a candidate's competence to practice. When the test is administered by computer, a valid pass/fail decision can be made with fewer items than an equivalent paper/pencil test by targeting items at the passing score and…

  4. First-passage-time statistics of a Brownian particle driven by an arbitrary unidimensional potential with a superimposed exponential time-dependent drift

    NASA Astrophysics Data System (ADS)

    Urdapilleta, Eugenio

    2015-12-01

    In one-dimensional systems, the dynamics of a Brownian particle are governed by the force derived from a potential as well as by diffusion properties. In this work, we obtain the first-passage-time statistics of a Brownian particle driven by an arbitrary potential with an exponential temporally decaying superimposed field up to a prescribed threshold. The general system analyzed here describes the sub-threshold signal integration of integrate-and-fire neuron models, of any kind, supplemented by an adaptation-like current, whereas the first-passage-time corresponds to the declaration of a spike. Following our previous studies, we base our analysis on the backward Fokker-Planck equation and study the survival probability and the first-passage-time density function in the space of the initial condition. By proposing a series solution we obtain a system of recurrence equations, which given the specific structure of the exponential time-dependent drift, easily admit a simpler Laplace representation. Naturally, the present general derivation agrees with the explicit solution we found previously for the Wiener process in (2012 J. Phys. A: Math. Theor. 45 185001). However, to demonstrate the generality of the approach, we further explicitly evaluate the first-passage-time statistics of the underlying Ornstein-Uhlenbeck process. To test the validity of the series solution, we extensively compare theoretical expressions with the data obtained from numerical simulations in different regimes. As shown, agreement is precise whenever the series is truncated at an appropriate order. Beyond the fact that both the Wiener and Ornstein-Uhlenbeck processes have a direct interpretation in the context of neuronal models, given their ubiquity in different fields, our present results will be of interest in other settings where an additive state-independent temporal relaxation process is being developed as the particle diffuses.

  5. Assessing the Unidimensionality of the School and College Ability Test (SCAT, Spanish Version) Using Non-Parametric Methods Based on Item Response Theory

    ERIC Educational Resources Information Center

    Touron, Javier; Lizasoain, Luis; Joaristi, Luis

    2012-01-01

    The aim of this work is to analyze the dimensional structure of the Spanish version of the School and College Ability Test, employed in the process for the identification of students with high intellectual abilities. This test measures verbal and mathematical (or quantitative) abilities at three levels of difficulty: elementary (3rd, 4th, and 5th…

  6. Rede und Gesinnung (Speech and Ways of Thinking)

    ERIC Educational Resources Information Center

    Kienzle, Bertram

    1974-01-01

    Analyzes some of the basic ideas in Georg Franklin's book "Versuch einer neuen Lehre von den vornehmsten Gegenstanden der deutschen Sprachlehre; nach den Regeln der Vernunftlehre in sechs Abhandlungen verfasst" (1778) and compares them to those of such modern linguists and philosophers a s Searle, Austin and Wunderlich. Concludes that the…

  7. The Short Mood and Feelings Questionnaire (SMFQ): a unidimensional item response theory and categorical data factor analysis of self-report ratings from a community sample of 7-through 11-year-old children.

    PubMed

    Sharp, Carla; Goodyer, Ian M; Croudace, Tim J

    2006-06-01

    Item response theory (IRT) and categorical data factor analysis (CDFA) are complementary methods for the analysis of the psychometric properties of psychiatric measures that purport to measure latent constructs. These methods have been applied to relatively few child and adolescent measures. We provide the first combined IRT and CDFA analysis of a clinical measure (the Short Mood and Feelings Questionnaire--SMFQ) in a community sample of 7-through 11-year-old children. Both latent variable models supported the internal construct validity of a single underlying continuum of severity of depressive symptoms. SMFQ items discriminated well at the more severe end of the depressive latent trait. Item performance was not affected by age, although age correlated significantly with latent SMFQ scores suggesting that symptom severity increased within the age period of 7-11. These results extend existing psychometric studies of the SMFQ and confirm its scaling properties as a potential dimensional measure of symptom severity of childhood depression in community samples. PMID:16649000

  8. The Short Mood and Feelings Questionnaire (SMFQ): A Unidimensional Item Response Theory and Categorical Data Factor Analysis of Self-Report Ratings from a Community Sample of 7-through 11-Year-Old Children

    ERIC Educational Resources Information Center

    Sharp, Carla; Goodyer, Ian M.; Croudace, Tim J.

    2006-01-01

    Item response theory (IRT) and categorical data factor analysis (CDFA) are complementary methods for the analysis of the psychometric properties of psychiatric measures that purport to measure latent constructs. These methods have been applied to relatively few child and adolescent measures. We provide the first combined IRT and CDFA analysis of a…

  9. Astronomical Perception of the Secondary School's Students in São Paulo's State School in Suzano City. (Spanish Title: Percepción Astronómica de Alumnos de la Enseñanza Media de la Red Estatal de San Pablo en la Ciudad de Suzano.) Percepção Astronômica de um Grupo de Alunos do Ensino Médio da Rede Estadual de São Paulo da Cidade de Suzano

    NASA Astrophysics Data System (ADS)

    França de Oliveira, Edilene; Voelzke, Marcos Rincon; Amaral, Luis Henrique

    2007-12-01

    año y 20,6% tenían la idea de cuales son los objetos celestes más cercanos de la Tierra. En contraposición, 67,6% clasificaron correctamente el Sol como una estrella; 55,9% relacionaron el Big Bang al origen del Universo; solamente 20,6% identificaron un año-luz como unidad de distancia y 32,4% reconocieron una estrella fugaz como meteoro. El presente análisis fue expandido para otros grupos de la Enseñanza Media, no solamente del período nocturno, sino también diurno de la misma escuela. En esta primera fase se nota el pequeño conocimiento de los alumnos sobre eventos astronómicos y principalmente la gran confusión sobre el significado correcto de los términos astronómicos populares. Embora a Astronomia seja uma das ciências mais antigas da humanidade e muitos dos conceitos astronômicos serem populares, observa-se que uma parcela significativa dos estudantes encontra-se à margem dessas informações. O presente trabalho visa analisar o nível de conhecimento básico dos alunos do Ensino Médio da Rede Estadual da cidade de Suzano quanto aos fenômenos astronômicos que os rodeiam. Para tanto foi elaborado um formulário constando de questões de múltipla escolha, aplicado no primeiro ano noturno da Escola Estadual Batista Renzi. Num espaço amostral de 34 alunos constatou-se que apenas 29,4% compreendiam a sucessão dos dias; 20,6% explicaram corretamente as estações do ano e 20,6% tinham idéia de quais são os objetos celestes mais próximos da Terra. Em contraposição, 67,6% classificaram corretamente o Sol como estrela; 55,9% relacionaram o Big Bang à origem do Universo; apenas 20,6% identificaram um ano-luz como unidade de distância e 32,4% reconheceram uma estrela cadente como meteoro. A presente análise foi expandida para mais 310 alunos de outras classes de Ensino Médio, não somente do período noturno, mas também diurno da mesma escola. Nesta primeira fase nota-se o pequeno discernimento dos alunos sobre eventos astronômicos e

  10. Nuevas tecnicas basadas en redes neuronales para el diseno de filtros de microondas multicapa apantallados

    NASA Astrophysics Data System (ADS)

    Pascual Garcia, Juan

    In this PhD thesis one method of shielded multilayer circuit neural network based analysis has been developed. One of the most successful analysis procedures of these kind of structures is the Integral Equation technique (IE) solved by the Method of Moments (MoM). In order to solve the IE, in the version which uses the media relevant potentials, it is necessary to have a formulation of the Green's functions associated to the mentioned potentials. The main computational burden in the IE resolution lies on the numerical evaluation of the Green's functions. In this work, the circuit analysis has been drastically accelerated thanks to the approximation of the Green's functions by means of neural networks. Once trained, the neural networks substitute the Green's functions in the IE. Two different types of neural networks have been used: the Radial basis function neural networks (RBFNN) and the Chebyshev neural networks. Thanks mainly to two distinct operations the correct approximation of the Green's functions has been possible. On the one hand, a very effective input space division has been developed. On the other hand, the elimination of the singularity makes feasible the approximation of slow variation functions. Two different singularity elimination strategies have been developed. The first one is based on the multiplication by the source-observation points distance (rho). The second one outperforms the first one. It consists of the extraction of two layers of spatial images from the whole summation of images. With regard to the Chebyshev neural networks, the OLS training algorithm has been applied in a novel fashion. This method allows the optimum design in this kind of neural networks. In this way, the performance of these neural networks outperforms greatly the RBFNNs one. In both networks, the time gain reached makes the neural method profitable. The time invested in the input space division and in the neural training is negligible with only few circuit analysis. To show, in a practical way, the ability of the neural based analysis method, two new design procedures have been developed. The first method uses the Genetic Algorithms to optimize an initial filter which does not fulfill the established specifications. A new fitness function, specially well suited to design filters, has been defined in order to assure the correct convergence of the optimization process. This new function measures the fulfillment of the specifications and it also prevents the appearance of the premature convergence problem. The second method is found on the approximation, by means of neural networks, of the relations between the electrical parameters, which defined the circuit response, and the physical dimensions that synthesize the aforementioned parameters. The neural networks trained with these data can be used in the design of many circuits in a given structure. Both methods had been show their ability in the design of practical filters.

  11. Actividad funcional cerebral en estado de reposo: REDES EN CONEXIÓN

    PubMed Central

    Proal, Erika; Alvarez-Segura, Mar; de la Iglesia-Vayá, Maria; Martí-Bonmatí, Luis; Castellanos, F. Xavier

    2015-01-01

    Resumen El análisis de la conectividad funcional mediante resonancia magnética funcional (RMf) puede llevarse a cabo durante la realización de una tarea, la percepción de un estímulo o en estado de reposo. Estos análisis han demostrado su fiabilidad y reproducibilidad con diferentes enfoques (matemáticos, estadísticos, físicos) para seleccionar los vóxeles activados. El estudio de la señal de baja frecuencia en la actividad cerebral a través del contraste BOLD en estado de reposo ha revelado patrones de actividad cortical sincronizados, permitiendo describir la arquitectura funcional intrínseca del cerebro humano. La comunidad científica internacional dispone de recursos compartidos que contribuirán mediante este análisis de RMf en estado de reposo a la obtención de diagnósticos y tratamientos más precisos y avanzados en el campo de las neurociencias. PMID:21365601

  12. Assessing the Dimensionality of NAEP Reading Data.

    ERIC Educational Resources Information Center

    Zwick, Rebecca

    1987-01-01

    National Assessment of Educational Progress reading data were scaled using a unidimensional item response theory model. Bock's full-information factor analysis and Rosenbaum's test of unidimensionality were applied. Conclusions about unidimensionality for balanced incomplete block spiralled data were the same as for complete data. (Author/GDC)

  13. Utilization of nuclear structural proteins for targeted therapy and detection of proliferative and differentiation disorders

    DOEpatents

    Lelievre, Sophie; Bissell, Mina

    2001-01-01

    The localization of nuclear apparatus proteins (NUMA) is used to identify tumor cells and different stages in the tumor progression and differentiation processes. There is a characteristic organization of NuMA in tumor cells and in phenotypically normal cells. NuMA distribution patterns are significantly less diffuse in proliferating non-malignant cells compared to malignant cells. The technique encompasses cell immunostaining using a NuMA specific antibody, and microscopic analysis of NuMA distribution within each nucleus.

  14. The Moon Phases in a Paper Box. (Spanish Title: Las Fases de la Luna en Una Caja de Cartón.) As Fases da Lua Numa Caixa de Papelão

    NASA Astrophysics Data System (ADS)

    de Fátima O. Saraiva, Maria; Amador, Cláudio B.; Kemper, Érico; Goulart, Paulo; Muller, Angela

    2007-12-01

    We present a very simple concrete model to demonstrate the concept of phases of an illuminated body. The main objective of our model is to help the understanding of the Moon phases as viewed from the perspective of an observer on Earth. The material allows the visualization of two important effects: (1st) even though all the time half Moon is illuminated by the Sun, we see different fractions of the illuminated Moon surface, depending on our angle of sight; (2nd) the orientation of the convex part of the Moon in the crescent and waning phases on the sky also depends on our perspective from Earth. The use of a closed box allows one to see the contrast among the different phases with no need of a dark room. We also present a text on the Moon phases, emphasizing the dependence of the aspect of the bright part on the angle of sight. En este trabajo proponemos la construcción de material didáctico de bajo costo para demostración del concepto de fases de un cuerpo iluminado. El principal objetivo de nuestro material es facilitar la comprensión de las fases de la Luna desde la perspectiva de un observador en la Tierra. El material ayuda la visualización de dos efectos importantes: (1º) a pesar de tener siempre la mitad de la Luna (representada por una bolita de espuma plástica o de ping-pong), iluminada por el Sol ( representado por una fuente de luz natural o artificial), vemos diferentes fracciones de su superficie iluminada, dependiendo del ángulo por el cual la vemos; (2º) la orientación del borde convexo de la Luna en las fases Creciente y Menguante también depende de la perspectiva por la cual la miramos desde la Tierra. El uso de una caja cerrada permite observar el contraste entre las diferentes fases sin necesidad de estar en un recinto oscuro. Presentamos también un texto explicativo sobre las fases de la Luna, enfatizando la dependencia de la apariencia de la parte iluminada con el ángulo de visión. Neste trabalho propomos a construção de material didático de baixo custo para demonstração do conceito de fases de um corpo iluminado. O principal objetivo de nosso material é facilitar a compreensão das fases da Lua da perspectiva de um observador na Terra. O material ajuda na visualização de dois efeitos importantes: (1º) mesmo tendo sempre a metade da "Lua" (representada por uma bolinha de isopor ou de ping-pong) iluminada pelo "Sol" (representado por uma fonte de luz natural ou artificial), nós vemos diferentes frações de sua superfície iluminada, dependendo do ângulo pelo qual a olhamos; (2º) a orientação da borda convexa da Lua nas fases Crescente e Minguante também depende da perspectiva pela qual a olhamos da Terra. O uso de uma caixa fechada permite observar o contraste entre as diferentes fases sem necessidade de estar em uma sala escurecida. Apresentamos também um texto explicativo sobre fases da Lua, enfatizando a dependência da aparência da parte iluminada com o ângulo de visada.

  15. Actividad solar del ciclo 23. Predicción del máximo y fase decreciente utilizando redes neuronales

    NASA Astrophysics Data System (ADS)

    Parodi, M. A.; Ceccatto, H. A.; Piacentini, R. D.; García, P. J.

    Different methods have been proposed in order to predict the maximum amplitude of solar cycles, either as a consequence of the intrinsic importance of this event and because of its relation with solar storms and possible effects upon satellites, communication systems, etc. In this work, a neural network solar activity prediction is presented, measured through the sunspot number (SSN). The 16-units neural network, with a 12:3:1 architecture, was trained in a ``feed-forward" propagation way and learning by the so called ``back propagation rule". The annual mean SSN data in the 1700-1975 and 1987-1998 periods were used as the training set. The solar cycle 21 (1976-1986) was taken as the cross-validation data set. After performing the network training we obtained a prediction of the maximum annual mean for the current solar cycle 23, SSNmax= 135 ±17 at the year 2000, which is 13% smaller than the International Consensus Commitee's mean maximum prediction obtained through ``precursor techniques". On the other hand, our prediction is only about 4% smaller than the Consensus's neural network mean prediction. A ``multiple step" prediction technique was also performed and SSN annual mean predicted values for the near-maximum (from the present year 1999 to beyond the maximum) and the declining activity of solar cycle 23 are presented in this work. The sensibility of predictions is also tested. To do so, we changed the interval width and comparated our results with those of a previous neural network prediction and those of others authors using differents methods.

  16. Why Factor Analysis Often Is the Incorrect Model for Analyzing Bipolar Concepts, and What Model To Use Instead.

    ERIC Educational Resources Information Center

    van Schuur, Wijbrandt H.; Kiers, Henk A. L.

    1994-01-01

    The identification of two factors when one factor is expected is an artifact caused by using factor analysis on data that would be more appropriately analyzed with a unidimensional unfolding model. A numerical illustration is given, and ways to determine whether data conform to the unidimensional unfolding model are reviewed. (SLD)

  17. Calibration of Response Data Using MIRT Models with Simple and Mixed Structures

    ERIC Educational Resources Information Center

    Zhang, Jinming

    2012-01-01

    It is common to assume during a statistical analysis of a multiscale assessment that the assessment is composed of several unidimensional subtests or that it has simple structure. Under this assumption, the unidimensional and multidimensional approaches can be used to estimate item parameters. These two approaches are equivalent in parameter…

  18. The DSM-IV Construct of Cocaine Dependence in a Treatment Sample of Black, Mexican American, and White Men.

    ERIC Educational Resources Information Center

    Schafer, John; Caetano, Raul

    1996-01-01

    The unidimensionality of the fourth edition of the "Diagnostic and Statistical Manual of Mental Disorders" (DSM-IV) construct of cocaine dependence was examined among 263 black, 212 Mexican American, and 256 white men in treatment. Results generally support a unidimensional model of the cocaine dependence indicators, with one indicator considered…

  19. Simultaneous Estimation of Overall and Domain Abilities: A Higher-Order IRT Model Approach

    ERIC Educational Resources Information Center

    de la Torre, Jimmy; Song, Hao

    2009-01-01

    Assessments consisting of different domains (e.g., content areas, objectives) are typically multidimensional in nature but are commonly assumed to be unidimensional for estimation purposes. The different domains of these assessments are further treated as multi-unidimensional tests for the purpose of obtaining diagnostic information. However, when…

  20. Formulation of a DIMTEST Effect Size Measure (DESM) and Evaluation of the DESM Estimator Bias

    ERIC Educational Resources Information Center

    Seo, Minhee; Roussos, Louis A.

    2010-01-01

    DIMTEST is a widely used and studied method for testing the hypothesis of test unidimensionality as represented by local item independence. However, DIMTEST does not report the amount of multidimensionality that exists in data when rejecting its null. To provide more information regarding the degree to which data depart from unidimensionality, a…

  1. Projective Item Response Model for Test-Independent Measurement

    ERIC Educational Resources Information Center

    Ip, Edward Hak-Sing; Chen, Shyh-Huei

    2012-01-01

    The problem of fitting unidimensional item-response models to potentially multidimensional data has been extensively studied. The focus of this article is on response data that contains a major dimension of interest but that may also contain minor nuisance dimensions. Because fitting a unidimensional model to multidimensional data results in…

  2. One or Two Dimensions in Spontaneous Classification: A Simplicity Approach

    ERIC Educational Resources Information Center

    Pothos, Emmanuel M.; Close, James

    2008-01-01

    When participants are asked to spontaneously categorize a set of items, they typically produce unidimensional classifications, i.e., categorize the items on the basis of only one of their dimensions of variation. We examine whether it is possible to predict unidimensional vs. two-dimensional classification on the basis of the abstract stimulus…

  3. A Note on the Dimensionality of Quality of Life Scales: An Illustration with the Satisfaction with Life Scale (SWLS)

    ERIC Educational Resources Information Center

    Slocum-Gori, Suzanne L.; Zumbo, Bruno D.; Michalos, Alex C.; Diener, Ed

    2009-01-01

    A case is made that measures used in quality of life and happiness research will be essentially unidimensional: inherently tapping minor dimensions. This is illustrated using Diener's Satisfaction with Life Scale (SWLS). It is shown that the SWLS does not meet the standard of strict unidimensionality, but that the interpretation of the total scale…

  4. Extracción de conocimiento en bases de datos astronómicas mediante redes de neuronas artificiales: aplicaciones en la misión Gaia

    NASA Astrophysics Data System (ADS)

    Fustes Villadóniga, Diego

    2014-02-01

    In the so-called IT era, the capabilities of data acquisition systems have increased to such an extent that it has become difficult to store all the information they produce, and analyse it. This explosion of data has recently appeared in the field of Astronomy, where an increasing number of objects are being observed on a regular basis. An example of this is the upcoming Gaia mission, which will pick up multiple properties of a billion stars, whose information will have a volume of approximately a petabyte. The analysis of a similar amount of information inevitably requires the development of new data analysis methods to extract all the knowledge it contains. This thesis is devoted to the development of data analysis methods to be integrated in the Gaia pipeline, such that knowledge can be extracted from the data collected by the mission. In order to analyze the data from the Gaia mission, the European Space Agency organized the Data Processing and Analysis Consortium (DPAC) which is composed of hundreds of scientists and engineers. DPAC is divided into eight Coordination Units (CUs). This thesis is dedicated to algorithm development in CU8, which is responsible for source classification and astrophysical parameters (AP) estimation. Methods based on Artificial Neural Networks (ANNs) are developed to perform the tasks related to two different work packages in CU8: the GSP-Spec package (GWP-823), and the OA package (GWP-836). The GSP-Spec package is responsible for estimating stellar APs by means of the Radial Velocity Spectrograph (RVS) spectrum. This work presents the development of one of the GSP-Spec modules, which is based on the application of feed-forward ANNs. A methodology is described, based on the optimization of genetic algorithms and aimed at obtaining an optimal set of configuration parameters for the ANN in each case, depending on the signal to noise ratio (SNR) in the RVS spectrum and on the type of star to parameterize. Furthermore, in order to improve the AP estimates, wavelet signal processing techniques, applied to the RVS spectrum, are studied. Despite the effectiveness shown by ANNs in estimating APs, in principle they lack the ability to provide an uncertainty value on these estimates, making it impossible to determine their reliability. Because of this, a new architecture for the ANN is presented in which the inputs and outputs are reversed, so that the ANN estimates the RVS spectrum from the APs. Such an architecture is called Generative ANN (GANN) and is applied to the AP estimation of a set of simulated RVS spectra for the Gaia mission, where it is more effective than the conventional ANN model, in the case of faint stars with low SNR. Finally, the GANN can be applied for obtaining the posterior probability of each of the APs according to the RVS spectrum, allowing for their more complete analysis. Given the nature of the Gaia mission, which is the first astronomical mission that will observe, in an unbiased way, the entire sky up to magnitude 20, a large number of outliers are expected. The OA package in CU8 handles the processing of this type of objects, which are defined as those that could not be reliably classified by the methods in the upstream classification packages. OA methods are based on the unsupervised learning of all outliers. Such learning has two parts: clustering and dimensionality reduction. The Self-Organizing Map (SOM) algorithm is selected as a basis for this learning. Its effectiveness is demonstrated when it is applied, with an optimal configuration, to the Gaia simulations. Furthermore, the algorithm is applied to real outliers from the SDSS catalog. Since a subsequent identification of the clusters obtained by the SOM is necessary, two different methods of identification are applied. The first method is based on the similarity between the SOM prototypes and the Gaia simulations, and the second method is based on the recovery of stored classifications in the SIMBAD catalog by cross-matching celestial coordinates. Thanks to the visualization of the SOM planes, and to both

  5. Textlinguistik und Schulunterricht. Am Beispiel der Behandlung der indirekten Rede im Englischen. (Text Linguistics and Instruction in the Schools: Example: The Treatment of Indirect Discourse in English).

    ERIC Educational Resources Information Center

    Kueper, Christoph

    1979-01-01

    Compares sentence grammar with text linguistics, giving a survey of the treatment of indirect discourse in school grammars, and finding them inadequate. Recommends rules derived from text linguistics in spite of their greater complexity, because they do not hold the student to mechanical recasting of sentences. (IFS/WGA)

  6. Die Indirekte Rede als Diskursstrategie: Innovative Lehrmethoden zum Konjunktiv I (Indirect Speech as a Discourse Strategy: Innovative Teaching Methods for the Subjunctive).

    ERIC Educational Resources Information Center

    Gramberg, Anne-Kathrin; Heinze, Karin U.

    1993-01-01

    This article talks about the subjunctive of indirect speech, in which its important functions and meanings are depicted. An analysis of the instructional materials used in the first and second years of language study, followed by practical curriculum recommendations, demonstrates how this grammatical phenomenon can be established in an advanced…

  7. Pragma- und textilinguistische Untersuchungsmethoden zur indirekten Rede im Englischen (Pragmatic and Text-Linguistic Research Methods on Indirect Discourse in English)

    ERIC Educational Resources Information Center

    Ziegesar, Detlef von

    1976-01-01

    Examines the mechanisms involved in changing from direct to indirect discourse, taking as a starting point research findings in linguistic pragmatics, which involve the practical application of speech symbol use between speaker and hearer. (Text is in German.) (IFS/WGA)

  8. Extracción de conocimiento en bases de datos astronómicas mediante redes de neuronas artificiales: aplicaciones en la misión Gaia

    NASA Astrophysics Data System (ADS)

    Fustes Villadóniga, Diego

    2014-02-01

    In the so-called IT era, the capabilities of data acquisition systems have increased to such an extent that it has become difficult to store all the information they produce, and analyse it. This explosion of data has recently appeared in the field of Astronomy, where an increasing number of objects are being observed on a regular basis. An example of this is the upcoming Gaia mission, which will pick up multiple properties of a billion stars, whose information will have a volume of approximately a petabyte. The analysis of a similar amount of information inevitably requires the development of new data analysis methods to extract all the knowledge it contains. This thesis is devoted to the development of data analysis methods to be integrated in the Gaia pipeline, such that knowledge can be extracted from the data collected by the mission. In order to analyze the data from the Gaia mission, the European Space Agency organized the Data Processing and Analysis Consortium (DPAC) which is composed of hundreds of scientists and engineers. DPAC is divided into eight Coordination Units (CUs). This thesis is dedicated to algorithm development in CU8, which is responsible for source classification and astrophysical parameters (AP) estimation. Methods based on Artificial Neural Networks (ANNs) are developed to perform the tasks related to two different work packages in CU8: the GSP-Spec package (GWP-823), and the OA package (GWP-836). The GSP-Spec package is responsible for estimating stellar APs by means of the Radial Velocity Spectrograph (RVS) spectrum. This work presents the development of one of the GSP-Spec modules, which is based on the application of feed-forward ANNs. A methodology is described, based on the optimization of genetic algorithms and aimed at obtaining an optimal set of configuration parameters for the ANN in each case, depending on the signal to noise ratio (SNR) in the RVS spectrum and on the type of star to parameterize. Furthermore, in order to improve the AP estimates, wavelet signal processing techniques, applied to the RVS spectrum, are studied. Despite the effectiveness shown by ANNs in estimating APs, in principle they lack the ability to provide an uncertainty value on these estimates, making it impossible to determine their reliability. Because of this, a new architecture for the ANN is presented in which the inputs and outputs are reversed, so that the ANN estimates the RVS spectrum from the APs. Such an architecture is called Generative ANN (GANN) and is applied to the AP estimation of a set of simulated RVS spectra for the Gaia mission, where it is more effective than the conventional ANN model, in the case of faint stars with low SNR. Finally, the GANN can be applied for obtaining the posterior probability of each of the APs according to the RVS spectrum, allowing for their more complete analysis. Given the nature of the Gaia mission, which is the first astronomical mission that will observe, in an unbiased way, the entire sky up to magnitude 20, a large number of outliers are expected. The OA package in CU8 handles the processing of this type of objects, which are defined as those that could not be reliably classified by the methods in the upstream classification packages. OA methods are based on the unsupervised learning of all outliers. Such learning has two parts: clustering and dimensionality reduction. The Self-Organizing Map (SOM) algorithm is selected as a basis for this learning. Its effectiveness is demonstrated when it is applied, with an optimal configuration, to the Gaia simulations. Furthermore, the algorithm is applied to real outliers from the SDSS catalog. Since a subsequent identification of the clusters obtained by the SOM is necessary, two different methods of identification are applied. The first method is based on the similarity between the SOM prototypes and the Gaia simulations, and the second method is based on the recovery of stored classifications in the SIMBAD catalog by cross-matching celestial coordinates. Thanks to the visualization of the SOM planes, and to both methods of identification, it is possible to distinguish between valid observations and observational artifacts. Furthermore, the method allows for the selection of objects of interest for follow-up observations, in order to determine their nature.

  9. Differentiation inducing factor-1 (DIF-1) induces gene and protein expression of the Dictyostelium nuclear calmodulin-binding protein nucleomorphin.

    PubMed

    O'Day, Danton H; Poloz, Yekaterina; Myre, Michael A

    2009-02-01

    The nucleomorphin gene numA1 from Dictyostelium codes for a multi-domain, calmodulin binding protein that regulates nuclear number. To gain insight into the regulation of numA, we assessed the effects of the stalk cell differentiation inducing factor-1 (DIF-1), an extracellular signalling molecule, on the expression of numA1 RNA and protein. For comparison, the extracellular signalling molecules cAMP (mediates chemotaxis, prestalk and prespore differentiation) and ammonia (NH(3)/NH(4)(+); antagonizes DIF) were also studied. Starvation, which is a signal for multicellular development, results in a greater than 80% decrease in numA1 mRNA expression within 4 h. Treatment with ammonium chloride led to a greater than 90% inhibition of numA1 RNA expression within 2 h. In contrast, the addition of DIF-1 completely blocked the decrease in numA1 gene expression caused by starvation. Treatment of vegetative cells with cAMP led to decreases in numA1 RNA expression that were equivalent to those seen with starvation. Western blotting after various morphogen treatments showed that the maintenance of vegetative levels of numA1 RNA by DIF-1 in starved cells was reflected in significantly increased numA1 protein levels. Treatment with cAMP and/or ammonia led to decreased protein expression and each of these morphogens suppressed the stimulatory effects of DIF-1. Protein expression levels of CBP4a, a calcium-dependent binding partner of numA1, were regulated in the same manner as numA1 suggesting this potential co-regulation may be related to their functional relationship. NumA1 is the first calmodulin binding protein shown to be regulated by developmental morphogens in Dictyostelium being upregulated by DIF-1 and down-regulated by cAMP and ammonia. PMID:19000924

  10. 76 FR 59180 - Agency Information Collection Activities: Proposed Request and Comment Request

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-23

    ... criteria. Respondents complete Form SSA-1026-REDE under the following circumstances: (1) When individuals...-SM-REDE 225,000 1 18 67,500 Total 236,400 70,920 II. SSA submitted the information collection...

  11. Understanding Spatial Statistics for Purposes of Identifying Non-Primary and Saturated Impact Crater Populations

    NASA Astrophysics Data System (ADS)

    Riggs, J. D.; Robbins, S. J.; Kirchoff, M. R.; Bierhaus, E. B.; Weaver, B. P.

    2015-05-01

    We discuss some traditional unidimensional summarization statistics and some newer spatial point statistical methods for understanding and identifying non-primary and saturated impact crater populations observed on a variety of solar system bodies.

  12. Investigating the Impact of Item Parameter Drift for Item Response Theory Models with Mixture Distributions.

    PubMed

    Park, Yoon Soo; Lee, Young-Sun; Xing, Kuan

    2016-01-01

    This study investigates the impact of item parameter drift (IPD) on parameter and ability estimation when the underlying measurement model fits a mixture distribution, thereby violating the item invariance property of unidimensional item response theory (IRT) models. An empirical study was conducted to demonstrate the occurrence of both IPD and an underlying mixture distribution using real-world data. Twenty-one trended anchor items from the 1999, 2003, and 2007 administrations of Trends in International Mathematics and Science Study (TIMSS) were analyzed using unidimensional and mixture IRT models. TIMSS treats trended anchor items as invariant over testing administrations and uses pre-calibrated item parameters based on unidimensional IRT. However, empirical results showed evidence of two latent subgroups with IPD. Results also showed changes in the distribution of examinee ability between latent classes over the three administrations. A simulation study was conducted to examine the impact of IPD on the estimation of ability and item parameters, when data have underlying mixture distributions. Simulations used data generated from a mixture IRT model and estimated using unidimensional IRT. Results showed that data reflecting IPD using mixture IRT model led to IPD in the unidimensional IRT model. Changes in the distribution of examinee ability also affected item parameters. Moreover, drift with respect to item discrimination and distribution of examinee ability affected estimates of examinee ability. These findings demonstrate the need to caution and evaluate IPD using a mixture IRT framework to understand its effects on item parameters and examinee ability. PMID:26941699

  13. Investigating the Impact of Item Parameter Drift for Item Response Theory Models with Mixture Distributions

    PubMed Central

    Park, Yoon Soo; Lee, Young-Sun; Xing, Kuan

    2016-01-01

    This study investigates the impact of item parameter drift (IPD) on parameter and ability estimation when the underlying measurement model fits a mixture distribution, thereby violating the item invariance property of unidimensional item response theory (IRT) models. An empirical study was conducted to demonstrate the occurrence of both IPD and an underlying mixture distribution using real-world data. Twenty-one trended anchor items from the 1999, 2003, and 2007 administrations of Trends in International Mathematics and Science Study (TIMSS) were analyzed using unidimensional and mixture IRT models. TIMSS treats trended anchor items as invariant over testing administrations and uses pre-calibrated item parameters based on unidimensional IRT. However, empirical results showed evidence of two latent subgroups with IPD. Results also showed changes in the distribution of examinee ability between latent classes over the three administrations. A simulation study was conducted to examine the impact of IPD on the estimation of ability and item parameters, when data have underlying mixture distributions. Simulations used data generated from a mixture IRT model and estimated using unidimensional IRT. Results showed that data reflecting IPD using mixture IRT model led to IPD in the unidimensional IRT model. Changes in the distribution of examinee ability also affected item parameters. Moreover, drift with respect to item discrimination and distribution of examinee ability affected estimates of examinee ability. These findings demonstrate the need to caution and evaluate IPD using a mixture IRT framework to understand its effects on item parameters and examinee ability. PMID:26941699

  14. Subgrouping For Patients With Low Back Pain: A Multidimensional Approach Incorporating Cluster Analysis & The STarT Back Screening Tool

    PubMed Central

    Beneciuk, Jason M.; Robinson, Michael E.; George, Steven Z.

    2014-01-01

    Early screening for psychological distress has been suggested to improve patient management for individuals experiencing low back pain. This study compared two approaches to psychological screening (i.e., multidimensional and unidimensional) so that preliminary recommendations on which approach may be appropriate for use in clinical settings other than primary care could be provided. Specifically, this study investigated STarT Back Screening Tool (SBT): 1) discriminant validity by evaluating its relationship with unidimensional psychological measures and 2) construct validity by evaluating how SBT risk categories compared to empirically derived subgroups using unidimensional psychological and disability measures. Patients (n = 146) receiving physical therapy for LBP were administered the SBT and a battery of unidimensional psychological measures at initial evaluation. Clinical measures consisted of pain intensity and self-reported disability. Several SBT risk dependent relationships (i.e., SBT low < medium < high risk) were identified for unidimensional psychological measure scores with depressive symptom scores associated with the strongest influence on SBT risk categorization. Empirically derived subgroups indicated that there was no evidence of distinctive patterns amongst psychological or disability measures other than high or low profiles, therefore two groups may provide a more clear representation of the level of pain associated psychological distress, maladaptive coping and disability in this setting, as compared to three groups which have been suggested when using the SBT in primary care settings. PMID:25451622

  15. Análise sobre o Conhecimento de um Grupo de Alunos do Ensino Médio da Rede Estadual de São Paulo sobre Termos e Fenômenos Astronômicos do Cotidiano

    NASA Astrophysics Data System (ADS)

    de Oliveira, E. F.; Voelzke, M. R.; Amaral, L. H.

    2007-08-01

    Embora os Parâmetros Curriculares Nacionais do Ensino Médio (PCN-EM) e as orientações complementares a esses Parâmetros (PCN+) apontem a importância de uma abordagem significativa de conceitos relacionados à astronomia nas aulas de Física, muitos estudantes terminam o Ensino Médio (EM) sem compreender a razão de certos acontecimentos de origem celeste, ainda que estes façam parte de seu cotidiano. Este trabalho tem por objetivo analisar os conhecimentos básicos em astronomia dos alunos de EM da escola estadual Batista Renzi, bem como investigar os meios através dos quais estes conhecimentos foram adquiridos. Para tanto foi elaborado um questionário de múltipla escolha aplicado a 310 alunos distribuídos entre as três séries do EM dos períodos matutino e noturno. Dessa forma, observou-se que apenas 34,5% relacionaram as estações do ano à inclinação do eixo de rotação da Terra, 21,3% indicaram a influência gravitacional da Lua e do Sol como responsáveis pelo fenômeno das marés, 24,5% indicaram corretamente quais são os objetos celestes mais próximos da Terra, 36,1% identificaram ano-luz como uma medida de distância e 34,2% reconheceram uma estrela cadente como meteoro. Em contrapartida, 67,1% compreendiam a sucessão entre dia e noite, 73,9% identificaram o Sol como estrela e 52,3% relacionaram o Big Bang à origem do Universo. Além disso, foram comparadas as respostas de alunos de diferentes séries e períodos, observando-se, dentre outras coisas, que os estudantes do terceiro ano apresentam um percentual de acertos semelhante ao dos alunos do primeiro, caracterizando que a abordagem de tópicos relacionados à astronomia no EM não tem contribuído para uma maior compreensão dos fenômenos e conceitos.

  16. Aplicación de técnicas de análisis de redes sociales y de co-ocurrencia de palabras en la determinación de frentes de investigación

    NASA Astrophysics Data System (ADS)

    Boeris, C. E.

    A bibliometric study of the scientific production of the IAR researchers has been performed, with the aim of determining the institute's research fronts and groups of researchers working on these fronts. Methods of analysis of co-occurrence of words, authorship analysis and social network analysis (SNA) has been applied by extracting keywords and the names of the authors on the base of published works. The results support the existence of two research fronts within the institution. FULL TEXT IN SPANISH

  17. Percepção astronómica de um grupo de alunos do ensino médio de uma escola da rede estadual de São Paulo

    NASA Astrophysics Data System (ADS)

    de Oliveria, E. F.; Voelzke, M. R.

    2009-03-01

    Sendo a Astronomia uma das cièncias mais antigas da humanidade, e considerando sua importáncia histórica e cultural, é de extrema releváncia que tópicos relacionados a ela sejam tratados nas escolas. Embora os Parámetros Curriculares Nacionais do Ensino Médio (PCN-EM) e as Orientaçiacute;es Complementares aos Parámetros (PCN+) apontem a importáncia de uma abordagem significativa de conceitos relacionados à Astronomia nas aulas de Física, muitos estudantes terminam o Ensino Médio (EM) sem compreender a razão de certos acontecimentos de origem celeste, ainda que estes façam parte de seu cotidiano e sejam alvos da curiosidade natural dos jovens. Da observação dessa curiosidade em alunos de uma escola pública paulista, na cidade de Suzano, surgiu o interesse em investigar os conhecimentos básicos em Astronomia dos alunos do Ensino Médio desta escola, constituindo-se este como principal objetivo desta pesquisa. Para tanto foi elaborado um questionário de múltipla escolha aplicado inicialmente a 34 alunos do primeiro ano e, posteriormente, a mais 310, distribuídos entre as très séries do Ensino Médio dos períodos matutino e noturno. Dessa forma, observou-se que 73,9% dos estudantes identificaram o Sol como sendo uma estrela, 67,1% mostraram compreender a sucessão entre dia e noite e 52,3% relacionaram o Big Bang à origem do Universo. Em contrapartida, apenas 34,5% relacionaram as estaçíes do ano à inclinação do eixo de rotação da Terra, 21,3% indicaram a influència gravitacional simultánea da Lua e do Sol como responsável pelo fenòmeno das marés, 24,5% indicaram corretamente quais são os objetos celestes mais próximos da Terra, 36,1% identificaram ano-luz como uma medida de distáncia e 34,2% reconheceram as estrelas cadentes como meteoros, evidenciando-se assim o pequeno discernimento dos estudantes quanto aos fenòmenos e termos astronòmicos do cotidiano. Além disso, foram comparadas as respostas de alun! os de diferentes séries e períodos, observando-se, dentre ou tras coi sas, que os estudantes do terceiro ano apresentam um percentual de acertos semelhante ao dos alunos do primeiro, caracterizando que a abordagem de tópicos relacionados à astronomia no Ensino Médio não tem contribuído de forma significativa para uma maior compreensão dos fenòmenos e conceitos.

  18. Memorias Conferencia Internacional IEEE Mexico 1971, Sobre Sistemas, Redes Y Computadoras. Volumen I and Volumen II. (Proceedings of International Conference of IEEE Concerning Systems, Networks, and Computers. Volume I and Volume II.

    ERIC Educational Resources Information Center

    Concheiro, A. Alonso, Ed.; And Others

    The following papers in English from this international conference may be of particular interest to those in the field of education. T. Nakahara, A. Tsukamota, and M. Matsumoto describe a computer-aided design technique for an economical urban cable television system. W. D. Wasson and R. K. Chitkara outline a recognition scheme based on analysis…

  19. Percepção Astronômica de um Grupo de Alunos do Ensino Médio de uma Escola da Rede Estadual de São Paulo

    NASA Astrophysics Data System (ADS)

    de Oliveira, E. F.

    2007-06-01

    Being the Astronomy one of the oldest sciences of the humanity, and considering its historical and cultural importance, it is of extreme relevance that topics related to it are taught and studied at schools. Although the National Curriculum Parameters of the Senior High School (PCN-EM) and the Complementary Orientations to the Parameters (PCN+) indicate the importance of a significant approach of concepts related to the Astronomy in the Physics classes, many students finish the Senior High School (EM) without understanding the reason of certain events of celestial origin, although these are part of their daily lives and are a subject of natural curiosity for the youngsters. From the perception of the natural curiosity of the students of a São Paulo's Public School in the city of Suzano, came up the interest to investigate the basic knowledge in Astronomy of the Senior High School students at this school, becoming this the main goal of this research. A questionnaire of multiple choices was elaborated and initially applied to 34 students of the first grade and later, to more 310 students. It was distributed among the three grades of the Senior High School in the morning and night periods. In the way, it was observed that 73.9% of the students identified the Sun as a star, 67.1% demonstrated to understand the succession between the day and the night and 52.3% related the Big Bang to the origin of the Universe. In compensation, only 34.5% related the seasons of the year to the inclination of the rotation axis of the Earth, 21.3% indicated the simultaneous gravitational influence of the Moon and the Sun as responsible for the tides phenomenon, 24.5% correctly indicated which are the closest celestial objects to the Earth, 36.1% identified the light-year as a distance measure and only 34.2% recognized the shooting stars as meteors, being evidenced the small discernment of the students about the phenomena and astronomical terms of the daily life. Besides, the answers of different grade students and periods were compared, being observed, among other things, that the third grade students present a percentile of correct answers similar to the performance of the first grade students, demonstrating that the approach of topics related to the astronomy in the Senior High School has not been contributing in a significant way to a better understanding of the phenomena and the concepts.

  20. Inclusion of Astronomy Themes in an Inovative Approach of Informal Physics Teaching for High School Students. (Spanish Title: Inclusión de Temas Astronómicos en Uma Abordaje Innovadora de la Enseñanza Informal de Física Para Estudiantes de Secumdaria.) Inclusão de Temas Astronômicos Numa Abordagem Inovadora do Ensino Informal de Física Para Estudantes do Ensino Médio

    NASA Astrophysics Data System (ADS)

    Tiara Mota, Aline; de Morais Bonomini, Iracema Ariel; Meloni Martins Rosado, Ricardo

    2009-12-01

    The current work reports on an experience on Astronomy education at the Federal University of Itajubá through an extra-curricular course offered for High School students. This initiative was motivated by the low attention paid to the Astronomy subjects at this stage of the Brazilian Formal Education, in spite that the National Curricular Parameters (PCN and PCN+, in Brazil) point out the importance of their inclusion Este artículo relata una experiencia en la enseñanza de la astronomía efectuada en la Universidad Federal de Itajubá en la forma de un curso de extensión orientado para los estudiantes del colegio secundario. Esta iniciativa surgió de constatar la poca atención dada a la Astronomía en esta etapa de la Educación formal brasileña, a pesar que los Parámetros Curriculares Nacionales (PCN y PCN+, en Brasil) destacan la importancia de su inclusión. Este artigo relata uma experiência em ensino de Astronomia realizada na Universidade Federal de Itajubá na forma de um curso de extensão voltado para alunos do Ensino Médio. Esta iniciativa surgiu da pouca atenção que se dá à Astronomia nesta etapa da Educação embora os Parâmetros Curriculares Nacionais (PCN e PCN+) apontem a importância de sua inclusão.

  1. Using multidimensional Rasch to enhance measurement precision: initial results from simulation and empirical studies.

    PubMed

    Mok, Magdalena Mo Ching; Xu, Kun

    2013-01-01

    This study aimed to explore the effect on measurement precision of multidimensional, as compared with unidimensional, Rasch measurement for constructing measures from multidimensional Likert-type scales. Many educational and psychological tests are multidimensional but common practice is to ignore correlations among the latent traits in these multidimensional scales in the measurement process. These practices may have serious validity and reliability implications. This study made use of both empirical data from 208,083 students, and simulated data simulated by 24 systematic combinations, each replicated 1000 times, of three conditions, namely, sample size, degree of dimensionality, and scale length to compare unidimensional and multidimensional approaches and to identify effects of sample size, dimensionality and scale length on measurement precision. Results showed that the multidimensional Rasch approach yielded more precise estimates than did unidimensional approach if the two dimensions were strongly correlated. The effect was more pronounced for long scales. PMID:23442326

  2. Cross-cultural equivalence in translation of the oral health impact profile: how to interpret the final score?

    PubMed

    Denis, Frederic; Trojak, Benoit; Rude, Nathalie

    2016-06-01

    The oral health impact profile (OHIP) is one of the most widely known oral health-related quality of life instruments. In Community Dentistry and Oral Epidemiology, MacEntee and Brondani report the results of a systematic review to identify acceptable methods for translating psychometric instruments for cross-cultural equivalence of the OHIP scale. But in no study has unidimensionality, one aspect of the validity of the internal structure of the scale, been verified, whereas it is a major psychometric step. In the absence of the study of unidimensionality, it is difficult to interpret the final score. The methodology of transcultural validation of the OHIP could be improved, and the study of the unidimensionality is a psychometrically necessary step for the interpretation of the finale score. PMID:26879212

  3. Periodontal disease activity: a development strategy for its investigation by means of accurate 3-dimensional clinical measurement.

    PubMed

    Watts, T L; Beards, C f; Ewing, P D; Leeman, S

    1995-03-01

    The central problem in all previous approaches to clinical assessment of periodontal disease activity is the use of unidimensional measurement, which implies a number of unjustifiable assumptions. In addition, the use of unidimensional probing measurement has established that there are several distinct problems of validity and reliability in currently available techniques. The present paper begins with an analysis of these matters, leading to an approach to accurate clinical measurement of periodontitis in 3 dimensions, with the possibility of future development of a valid system for assessing the nature of disease activity. PMID:7790525

  4. Problem Articulation and the Processes of Assistance: An Activity Theoretic View of Mediation in Game Play

    ERIC Educational Resources Information Center

    Stone, Lynda D.; Gutierrez, Kris D.

    2007-01-01

    In this article, we study a local adaptation of the Fifth Dimension [Cole, M. (1996). "Cultural psychology: A once and future discipline." Cambridge: Cambridge University Press] known as Las Redes (i.e., Networks of Collaboration in the Fifth Dimension) to examine how the multiple activity systems of Las Redes, e.g. the undergraduate course and…

  5. A Reliability Generalization Study on the Survey of Perceived Organizational Support: The Effects of Mean Age and Number of Items on Score Reliability

    ERIC Educational Resources Information Center

    Hellman, Chan M.; Fuqua, Dale R.; Worley, Jody

    2006-01-01

    The Survey of Perceived Organizational Support (SPOS) is a unidimensional measure of the general belief held by an employee that the organization is committed to him or her, values his or her continued membership, and is generally concerned about the employee's well-being. In the interest of efficiency, researchers are often compelled to use a…

  6. The Twofold Multidimensionality of Academic Self-Concept: Domain Specificity and Separation between Competence and Affect Components

    ERIC Educational Resources Information Center

    Arens, A. Katrin; Yeung, Alexander Seeshing; Craven, Rhonda G.; Hasselhorn, Marcus

    2011-01-01

    Academic self-concept is consistently proven to be multidimensional rather than unidimensional as it is domain specific in nature. However, each specific self-concept domain may be further separated into competence and affect components. This study examines the twofold multidimensionality of academic self-concept (i.e., its domain specificity and…

  7. Burnout: Testing for the Validity, Replication, and Invariance of Causal Structure across Elementary, Intermediate, and Secondary Teachers.

    ERIC Educational Resources Information Center

    Byrne, Barbara M.

    1994-01-01

    This study investigated the impact of organizational and personality factors on three factors of teacher burnout: emotional exhaustion, depersonalization, and reduced personal accomplishment. Results with 3,044 elementary, intermediate, and secondary teachers demonstrate that teacher burnout is not a unidimensional construct. (SLD)

  8. A Binary Programming Approach to Automated Test Assembly for Cognitive Diagnosis Models

    ERIC Educational Resources Information Center

    Finkelman, Matthew D.; Kim, Wonsuk; Roussos, Louis; Verschoor, Angela

    2010-01-01

    Automated test assembly (ATA) has been an area of prolific psychometric research. Although ATA methodology is well developed for unidimensional models, its application alongside cognitive diagnosis models (CDMs) is a burgeoning topic. Two suggested procedures for combining ATA and CDMs are to maximize the cognitive diagnostic index and to use a…

  9. The Evidence for a Subscore Structure in a Test of English Language Competency for English Language Learners

    ERIC Educational Resources Information Center

    Reckase, Mark D.; Xu, Jing-Ru

    2015-01-01

    How to compute and report subscores for a test that was originally designed for reporting scores on a unidimensional scale has been a topic of interest in recent years. In the research reported here, we describe an application of multidimensional item response theory to identify a subscore structure in a test designed for reporting results using a…

  10. Reliability and Validity of the Pilot National Board Dental Examination.

    ERIC Educational Resources Information Center

    Kramer, Gene A.; DeMarais, David R.

    1992-01-01

    This study found that the restructured National Board Dental Examination Part II is a reliable test assessing a full range of cognitive behaviors, and a unidimensional test of comprehensive general dentistry, suggesting better testing of knowledge and problem-solving skills than on the traditional examination. Performance on the pilot and…

  11. Le Modele de Rasch: les principes sous-jacents et son application a la validation de tests (The Rasch Model: Underlying Principles and Application to Test Validation).

    ERIC Educational Resources Information Center

    de Jong, John H. A. L.

    1988-01-01

    The one-parameter psychometric model known as the Rasch model is described and examined. The basic principles underlying the model and the concepts of unidimensionality, local stochastic independence, and additivity are explained in non-mathematical terms. The requirements of measurement procedures, the measurement of latent traits, the control on…

  12. Implications of Contemporary Intelligence Theories to Marketing Education

    ERIC Educational Resources Information Center

    Muncy, James A.

    2006-01-01

    In recent years, prominent psychologists have redefined intelligence to refer to one's ability to successfully perform within a sociocultural context. They have also questioned the historical unidimensional conceptualization of intelligence. In this article, the author briefly reviews the history of intelligence research to this point then…

  13. Objective Measurement of Fear of Success and Fear of Failure: A Factor Analytic Approach.

    ERIC Educational Resources Information Center

    Sadd, Susan; And Others

    1978-01-01

    Fear of success and failure scales were administered. Scores were intercorrelated. Results indicated fear of success is not unidimensional. Measures of fear of success and fear of failure were highly related. Stable orthogonal factors were obtained: fear of success, test anxiety, sex-role-related attitudes, neurotic insecurity, and the value of…

  14. Development and Validation of a 2 x 2 Model of Time-Related Academic Behavior: Procrastination and Timely Engagement

    ERIC Educational Resources Information Center

    Strunk, Kamden K.; Cho, YoonJung; Steele, Misty R.; Bridges, Stacey L.

    2013-01-01

    Procrastination is an educational concern for classroom instructors because of its negative psychological and academic impacts on students. However, the traditional view of procrastination as a unidimensional construct is insufficient in two regards. First, the construct needs to be viewed more broadly as time-related academic behavior,…

  15. Chemistry Education: Ten Facets to Shape Us

    ERIC Educational Resources Information Center

    Talanquer, Vicente

    2013-01-01

    The chemistry knowledge that we want our students to develop is rich, complex, and multifaceted. However, some teachers and instructors at the secondary school and college levels approach it in rather rigid and unidimensional ways. The central goal of this contribution is to describe and discuss 10 different complementary perspectives or…

  16. A Prospective Study Investigating the Impact of School Belonging Factors on Negative Affect in Adolescents

    ERIC Educational Resources Information Center

    Shochet, Ian M.; Smith, Coral L.; Furlong, Michael J.; Homel, Ross

    2011-01-01

    School belonging, measured as a unidimensional construct, is an important predictor of negative affective problems in adolescents, including depression and anxiety symptoms. A recent study found that one such measure, the Psychological Sense of School Membership scale, actually comprises three factors: Caring Relations, Acceptance, and Rejection.…

  17. A Mokken Scale to Assess Secondary Pupils' Experience of Violence in Terms of Severity

    ERIC Educational Resources Information Center

    Mooij, Ton

    2012-01-01

    Violence assessment can potentially be improved by Item Response Theory, that is, ordinal Mokken Scale Analysis. The research question is as follows: Does Mokken Scale Analysis of secondary pupils' experience of violence result in a homogeneous, reliable, and valid unidimensional scale that fits all the requirements of Mokken scaling? The method…

  18. A Model-Free Diagnostic for Single-Peakedness of Item Responses Using Ordered Conditional Means

    ERIC Educational Resources Information Center

    Polak, Marike; De Rooij, Mark; Heiser, Willem J.

    2012-01-01

    In this article we propose a model-free diagnostic for single-peakedness (unimodality) of item responses. Presuming a unidimensional unfolding scale and a given item ordering, we approximate item response functions of all items based on ordered conditional means (OCM). The proposed OCM methodology is based on Thurstone & Chave's (1929) "criterion…

  19. Confirming the Multidimensionality of Psychologically Controlling Parenting among Chinese-American Mothers: Love Withdrawal, Guilt Induction, and Shaming

    ERIC Educational Resources Information Center

    Yu, Jing; Cheah, Charissa S. L.; Hart, Craig H.; Sun, Shuyan; Olsen, Joseph A.

    2015-01-01

    Despite the theoretical conceptualization of parental psychological control as a multidimensional construct, the majority of previous studies have examined psychological control as a unidimensional scale. Moreover, the conceptualization of shaming and its associations with love withdrawal and guilt induction are unclear. The current study aimed to…

  20. In Search of the Illusive View of Man.

    ERIC Educational Resources Information Center

    Varenhorst, Barbara B.

    The author presents contemporary views of the quest for knowledge about human beings and the human experience. She then presents criticism of the natural science model as a basis for social and behavioral science research. She notes that the human being and his behavior are so complex that unidimensional research models are inadequate. However,…

  1. A Note on the Invariance of the DINA Model Parameters

    ERIC Educational Resources Information Center

    de la Torre, Jimmy; Lee, Young-Sun

    2010-01-01

    Cognitive diagnosis models (CDMs), as alternative approaches to unidimensional item response models, have received increasing attention in recent years. CDMs are developed for the purpose of identifying the mastery or nonmastery of multiple fine-grained attributes or skills required for solving problems in a domain. For CDMs to receive wider use,…

  2. Multiple-Group Noncompensatory Differential Item Functioning in Raju's Differential Functioning of Items and Tests

    ERIC Educational Resources Information Center

    Oshima, T. C.; Wright, Keith; White, Nick

    2015-01-01

    Raju, van der Linden, and Fleer (1995) introduced a framework for differential functioning of items and tests (DFIT) for unidimensional dichotomous models. Since then, DFIT has been shown to be a quite versatile framework as it can handle polytomous as well as multidimensional models both at the item and test levels. However, DFIT is still limited…

  3. The Relationship between Polytomous DFIT and Other Polytomous DIF Procedures.

    ERIC Educational Resources Information Center

    Flowers, Claudia P.; And Others

    An item response theory-based parametric procedure proposed by N. S. Raju, W. J. van der Linden, and P. F. Fleer (1995) known as differential functioning of items and tests (DFIT) can be used with unidimensional and multidimensional data with dichotomous or polytomous scoring. This study describes the polytomous DFIT framework and evaluates and…

  4. Development and Demonstration of Multidimensional IRT-Based Internal Measures of Differential Functioning of Items and Tests.

    ERIC Educational Resources Information Center

    Oshima, T. C.; Raju, Nambury S. Rajo; Flowers, Claudia P.

    1997-01-01

    Defines and demonstrates a framework for studying differential item functioning and differential test functioning for tests that are intended to be multidimensional. The procedure, which is illustrated with simulated data, is an extension of the unidimensional differential functioning of items and tests approach (N. Raju, W. van der Linden, and P.…

  5. Psychometric Properties of a Portuguese Version of the Subjective Happiness Scale

    ERIC Educational Resources Information Center

    Spagnoli, Paola; Caetano, Antonio; Silva, Ana

    2012-01-01

    The Subjective Happiness Scale (SHS) constitutes an instrument for assessing subjective happiness. This study aims to present the validation of the SHS in a Portuguese adult population. A large representative sample (1,017 participants), from five different age groups was considered. Configurational invariance of the unidimensional structure of…

  6. Performance of the S - [chi][squared] Statistic for Full-Information Bifactor Models

    ERIC Educational Resources Information Center

    Li, Ying; Rupp, Andre A.

    2011-01-01

    This study investigated the Type I error rate and power of the multivariate extension of the S - [chi][squared] statistic using unidimensional and multidimensional item response theory (UIRT and MIRT, respectively) models as well as full-information bifactor (FI-bifactor) models through simulation. Manipulated factors included test length, sample…

  7. The Mediating Effects of Parenting Behaviors on Maternal Affect and Reports of Children's Behavior

    ERIC Educational Resources Information Center

    Karazsia, Bryan T.; Wildman, Beth G.

    2009-01-01

    Parenting behaviors have received ample support as a mediator of the relationship between maternal affect and child behavior problems. The majority of these research efforts were based on a uni-dimensional conceptualization of maternal mood, even though decades of theory and research suggest that mood is multidimensional. We examined the mediating…

  8. Slower Implicit Categorical Learning in Adult Poor Readers

    ERIC Educational Resources Information Center

    Sperling, Anne J.; Lu, Zhong-Lin; Manis, Franklin R.

    2004-01-01

    We investigated the relationship between reading and explicit and implicit categorical learning by comparing university students with poor reading to students with normal reading abilities on two categorical learning tasks. One categorical learning task involved sorting simple geometric shapes into two groups according to a unidimensional rule.…

  9. Bully-Victimization Scale: Using Rasch Modeling in the Analysis of a Qualitative Scale

    ERIC Educational Resources Information Center

    Lehto, Marybeth

    2009-01-01

    The primary purpose of this study was to determine whether the data from the qualitative study fit Rasch model requirements for the definition of a measure, as well as to address concern in the extant literature regarding the appropriate number of items needed in analysis to assure unidimensionality. The self-report victimization scale was…

  10. Using the Advanced Progressive Matrices (Set I) to Assess Fluid Ability in a Short Time Frame: An Item Response Theory-Based Analysis

    ERIC Educational Resources Information Center

    Chiesi, Francesca; Ciancaleoni, Matteo; Galli, Silvia; Primi, Caterina

    2012-01-01

    This article is aimed at evaluating the possibility that Set I of the Advanced Progressive Matrices (APM-Set I) can be employed to assess fluid ability in a short time frame. The APM-Set I was administered to a sample of 1,389 primary and secondary school students. Confirmatory factor analysis attested to the unidimensionality of the scale. Item…

  11. Effortful Control in "Hot" and "Cool" Tasks Differentially Predicts Children's Behavior Problems and Academic Performance

    ERIC Educational Resources Information Center

    Kim, Sanghag; Nordling, Jamie Koenig; Yoon, Jeung Eun; Boldt, Lea J.; Kochanska, Grazyna

    2013-01-01

    Effortful control (EC), the capacity to deliberately suppress a dominant response and perform a subdominant response, rapidly developing in toddler and preschool age, has been shown to be a robust predictor of children's adjustment. Not settled, however, is whether a view of EC as a heterogeneous rather than unidimensional construct may offer…

  12. A Revised Semantic Differential Scale Distinguishing between Negative and Positive God Images

    ERIC Educational Resources Information Center

    Francis, Leslie J.; Robbins, Mandy; Gibson, Harry M.

    2006-01-01

    A sample of 755 school pupils between the ages of 11 and 18 years completed the Benson and Spilka semantic differential measure of God images. Factor analysis indicated the advantages of re-scoring the measure as an eight item unidimensional index, defining semantic space relating to God images ranging from negative affect to positive affect.…

  13. Best Design for Multidimensional Computerized Adaptive Testing with the Bifactor Model

    ERIC Educational Resources Information Center

    Seo, Dong Gi; Weiss, David J.

    2015-01-01

    Most computerized adaptive tests (CATs) have been studied using the framework of unidimensional item response theory. However, many psychological variables are multidimensional and might benefit from using a multidimensional approach to CATs. This study investigated the accuracy, fidelity, and efficiency of a fully multidimensional CAT algorithm…

  14. How Should We Use Student Ratings to Evaluate Teaching?

    ERIC Educational Resources Information Center

    Abrami, Philip C.

    1989-01-01

    Two divergent views are contrasted: the multidimensional and the unidimensional views of faculty evaluation. The views of H. W. Marsh, the most outspoken advocate of the multidimensional view of evaluation based on factor scores, is summarized and a response to his concerns is presented. (Author/MLW)

  15. Measuring Interpersonal Callousness in Boys from Childhood to Adolescence: An Examination of Longitudinal Invariance and Temporal Stability

    ERIC Educational Resources Information Center

    Obradovic, Jelena; Pardini, Dustin A.; Long, Jeffrey D.; Loeber, Rolf

    2007-01-01

    Studies show interpersonal callousness (IC) plays an important role in understanding persistent antisocial behaviors; however, it remains unclear whether IC is a unidimensional construct, represented by invariant behavioral indexes and stable across different developmental periods. This study explores the structure and stability of IC using parent…

  16. Dimensions, Patterns, and Personality Correlates of Drug Abuse in an Offender Population.

    ERIC Educational Resources Information Center

    Holland, Terrill R.

    1978-01-01

    Drug abuse scores from prisoners resulted in two factors describing lifetime use of cannabis versus opiates. Analysis of Minnesota Multiphasic Personality Inventory (MMPI) profiles versus drug abuse patterns indicated moderate, unidimensional relationship between variables. MMPI profiles of opiate users were similar to those identified in research…

  17. Community Agricultural Processing Services: A Reflection of Urban Differentiation or County Agricultural Structure.

    ERIC Educational Resources Information Center

    Moxley, Robert L.; Calloway, Michael O.

    Questionnaire data from 81 North Carolina communities were analyzed in 1981 to test the hypothesis that 5 institutional subcategories (education, general community services, transportation, agricultural services, and health and sanitation) exhibit the underlying characteristic of unidimensionality and that they reflect comparable levels of…

  18. Impact of Violation of the Missing-at-Random Assumption on Full-Information Maximum Likelihood Method in Multidimensional Adaptive Testing

    ERIC Educational Resources Information Center

    Han, Kyung T.; Guo, Fanmin

    2014-01-01

    The full-information maximum likelihood (FIML) method makes it possible to estimate and analyze structural equation models (SEM) even when data are partially missing, enabling incomplete data to contribute to model estimation. The cornerstone of FIML is the missing-at-random (MAR) assumption. In (unidimensional) computerized adaptive testing…

  19. An Application of Unfolding and Cumulative Item Response Theory Models for Noncognitive Scaling: Examining the Assumptions and Applicability of the Generalized Graded Unfolding Model

    ERIC Educational Resources Information Center

    Sgammato, Adrienne N.

    2009-01-01

    This study examined the applicability of a relatively new unidimensional, unfolding item response theory (IRT) model called the generalized graded unfolding model (GGUM; Roberts, Donoghue, & Laughlin, 2000). A total of four scaling methods were applied. Two commonly used cumulative IRT models for polytomous data, the Partial Credit Model and the…

  20. Bayesian Multidimensional IRT Models with a Hierarchical Structure

    ERIC Educational Resources Information Center

    Sheng, Yanyan; Wikle, Christopher K.

    2008-01-01

    As item response models gain increased popularity in large-scale educational and measurement testing situations, many studies have been conducted on the development and applications of unidimensional and multidimensional models. Recently, attention has been paid to IRT-based models with an overall ability dimension underlying several ability…

  1. On the Relationship between Classical Test Theory and Item Response Theory: From One to the Other and Back

    ERIC Educational Resources Information Center

    Raykov, Tenko; Marcoulides, George A.

    2016-01-01

    The frequently neglected and often misunderstood relationship between classical test theory and item response theory is discussed for the unidimensional case with binary measures and no guessing. It is pointed out that popular item response models can be directly obtained from classical test theory-based models by accounting for the discrete…

  2. A Multiple Motives Approach to Tobacco Dependence: The Wisconsin Inventory of Smoking Dependence Motives (WISDM-68)

    ERIC Educational Resources Information Center

    Piper, Megan E.; Piasecki, Thomas M.; Federman, E. Belle; Bolt, Daniel M.; Smith, Stevens S.; Fiore, Michael C.; Baker, Timothy C.

    2004-01-01

    The dependence construct fills an important explanatory role in motivational accounts of smoking and relapse. Frequently used measures of dependence are either atheoretical or grounded in a unidimensional model of physical dependence. This research creates a multidimensional measure of dependence that is based on theoretically grounded motives for…

  3. Electrohydrodynamically driven large-area liquid ion sources

    DOEpatents

    Pregenzer, Arian L.

    1988-01-01

    A large-area liquid ion source comprises means for generating, over a large area of the surface of a liquid, an electric field of a strength sufficient to induce emission of ions from a large area of said liquid. Large areas in this context are those distinct from emitting areas in unidimensional emitters.

  4. Sufficiency and Conditional Estimation of Person Parameters in the Polytomous Rasch Model

    ERIC Educational Resources Information Center

    Andrich, David

    2010-01-01

    Rasch models are characterised by sufficient statistics for all parameters. In the Rasch unidimensional model for two ordered categories, the parameterisation of the person and item is symmetrical and it is readily established that the total scores of a person and item are sufficient statistics for their respective parameters. In contrast, in the…

  5. How to Use Chromatography as a Science Teaching Aid.

    ERIC Educational Resources Information Center

    Ganis, Frank M.

    Presented are five procedures which permit the effective teaching of chromatography with equipment which is readily available, economical, and simple in design. The first procedure involves a study of solute partition in two immiscible solvents and of countercurrent distribution. The second illustrates the use of unidimensional ascending paper…

  6. Analysis of Letter Name Knowledge Using Rasch Measurement

    ERIC Educational Resources Information Center

    Bowles, Ryan P.; Skibbe, Lori E.; Justice, Laura M.

    2011-01-01

    Letter name knowledge (LNK) is a key predictor of later reading ability and has been emphasized strongly in recent educational policy. Studies of LNK have implicitly treated it as a unidimensional construct with all letters equally relevant to its measurement. However, some empirical research suggests that contextual factors can affect the…

  7. Comparison of Factor Simplicity Indices for Dichotomous Data: DETECT R, Bentler's Simplicity Index, and the Loading Simplicity Index

    ERIC Educational Resources Information Center

    Finch, Holmes; Stage, Alan Kirk; Monahan, Patrick

    2008-01-01

    A primary assumption underlying several of the common methods for modeling item response data is unidimensionality, that is, test items tap into only one latent trait. This assumption can be assessed several ways, using nonlinear factor analysis and DETECT, a method based on the item conditional covariances. When multidimensionality is identified,…

  8. When Cognitive Diagnosis Meets Computerized Adaptive Testing: CD-CAT

    ERIC Educational Resources Information Center

    Cheng, Ying

    2009-01-01

    Computerized adaptive testing (CAT) is a mode of testing which enables more efficient and accurate recovery of one or more latent traits. Traditionally, CAT is built upon Item Response Theory (IRT) models that assume unidimensionality. However, the problem of how to build CAT upon latent class models (LCM) has not been investigated until recently,…

  9. An Interactive Multiobjective Programming Approach to Combinatorial Data Analysis.

    ERIC Educational Resources Information Center

    Brusco, Michael J.; Stahl, Stephanie

    2001-01-01

    Describes an interactive procedure for multiobjective asymmetric unidimensional seriation problems that uses a dynamic-programming algorithm to generate partially the efficient set of sequences for small to medium-sized problems and a multioperational heuristic to estimate the efficient set for larger problems. Applies the procedure to an…

  10. Constructing Linkage Disequilibrium Map with Iterative Approach

    NASA Astrophysics Data System (ADS)

    Ao, S. I.

    2008-05-01

    With recent advance of the genotyping single nucleotide polymorphisms (SNPs) in mass scale of high density in a candidate region of the human genome, the linkage disequilibrium analysis can offer a much higher resolution of the biological samples than the traditional linkage maps. We have formulated this LD mapping problem as a constrained unidimensional scaling problem. Our method, which is directly based on the measurement of LD among SNPs, is non-parametric. Therefore it is different from LD maps derived from the given Malecot model. We have formulated with the quadratic programming approach for solving this constrained unidimensional scaling problem. Different from the classical metric unidimensional scaling problem, the constrained problem is not an NP-hard combinatorial problem. The optimal solution is determined by using the quadratic programming solver. Nevertheless, because of the large requirement for memory during the running time that may cause the out of memory problems, and the high computational time of the quadratic programming algorithm, the iterative algorithm has been developed for solving this LD constrained unidimensional scaling problem.

  11. Toward a Descriptive Science of Teaching: How the TDOP Illuminates the Multidimensional Nature of Active Learning in Postsecondary Classrooms

    ERIC Educational Resources Information Center

    Hora, Matthew T.

    2015-01-01

    Detailed accounts of teaching can shed light on the nature and prevalence of active learning, yet common approaches reduce teaching to unidimensional descriptors or binary categorizations. In this paper, I use the instructional systems-of-practice framework and the Teaching Dimensions Observation Protocol (TDOP) to advance an approach to thinking…

  12. Component Structure, Reliability, and Stability of Lawrence's Self-Esteem Questionnaire (LAWSEQ)

    ERIC Educational Resources Information Center

    Rae, Gordon; Dalto, Georgia; Loughrey, Dolores; Woods, Caroline

    2011-01-01

    Lawrence's Self-Esteem Questionnaire (LAWSEQ) was administered to 120 Year 1 pupils in six schools in Belfast, Northern Ireland. A principal components analysis indicated that the scale items were unidimensional and that the reliability of the scores, as estimated by Cronbach's alpha, was satisfactory ([alpha] = 0.73). There were no differences…

  13. Easier Said than Done: Rejoinder on Sijtsma and on Green and Yang

    ERIC Educational Resources Information Center

    Davenport, Ernest C.; Davison, Mark L.; Liou, Pey-Yan; Love, Quintin U.

    2016-01-01

    The main points of Sijtsma and Green and Yang in Educational Measurement: Issues and Practice (34, 4) are that reliability, internal consistency, and unidimensionality are distinct and that Cronbach's alpha may be problematic. Neither of these assertions are at odds with Davenport, Davison, Liou, and Love in the same issue. However, many authors…

  14. AHIMSA - Ad hoc histogram information measure sensing algorithm for feature selection in the context of histogram inspired clustering techniques

    NASA Technical Reports Server (NTRS)

    Dasarathy, B. V.

    1976-01-01

    An algorithm is proposed for dimensionality reduction in the context of clustering techniques based on histogram analysis. The approach is based on an evaluation of the hills and valleys in the unidimensional histograms along the different features and provides an economical means of assessing the significance of the features in a nonparametric unsupervised data environment. The method has relevance to remote sensing applications.

  15. Using Perceived Health to Test the Construct-Related Validity of Global Quality of Life

    ERIC Educational Resources Information Center

    Beckie, Theresa M.; Hayduk, Leslie A.

    2004-01-01

    Quality of life (QOL) is considered as a global, yet unidimensional, subjective assessment of one's satisfaction with life. We examine the construct validity of the available indicators of global QOL by constructing a causal model in which QOL is viewed as causally responding to several dimensions of perceived health. Global QOL is measured with…

  16. An Analysis of the Dimensionality of the Pupil Control Ideology Scale.

    ERIC Educational Resources Information Center

    Graham, Steve; And Others

    1985-01-01

    The present study replicated an earlier investigation using the Pupil Control Ideology (PCI). The findings were congruent with earlier results. Consequently, it was recommended that the PCI should be refined and that the 10 item, unidimensional scale should be used in future investigations. (Author/LMO)

  17. Sustainable Communities: A Lens for Envisioning and Achieving a Community-Based Culture of Social and Ecological Peace

    ERIC Educational Resources Information Center

    Verhagen, Frans C.

    2014-01-01

    One of the obstacles to dealing with the social and ecological crises that obstruct the achievement of a culture of peace is silo thinking in global governance. A unidimensional mode of planning, silo thinking leads to decisions based on the area of expertise of a particular agency or intergovernmental organization and fails to recognize linkages…

  18. A Confirmatory Factor Analysis of the Life Orientation Test-Revised with Competitive Athletes

    ERIC Educational Resources Information Center

    Appaneal, Renee N.

    2012-01-01

    Current reviews outside of sport indicate that the Life Orientation Test-Revised (LOT-R) items load on two separate factors (optimism and pessimism) and, therefore, should be treated as independent constructs. However, researchers in the sport sciences continue to use the single composite score reflecting a unidimensional definition of optimism.…

  19. Latent Trait Theory Approach to Measuring Person-Organization Fit: Conceptual Rationale and Empirical Evaluation

    ERIC Educational Resources Information Center

    Chernyshenko, Oleksandr S.; Stark, Stephen; Williams, Alex

    2009-01-01

    The purpose of this article is to offer a new approach to measuring person-organization (P-O) fit, referred to here as "Latent fit." Respondents were administered unidimensional forced choice items and were asked to choose the statement in each pair that better reflected the correspondence between their values and those of the organization;…

  20. Development of an Instrument to Measure Staff-Reported Resident-to-Resident Elder Mistreatment (R-REM) Using Item Response Theory and Other Latent Variable Models

    PubMed Central

    Ramirez, Mildred

    2014-01-01

    Objectives: Although numerous studies have measured behaviors among individuals in congregate settings, few have focused on resident-to-resident elder mistreatment (R-REM). To our knowledge, there is no psychometrically developed measure of R-REM extant. The quantitative development of a measure of staff-reported R-REM is described. Methods: The design was a prevalent cohort study of residents of 5 long-term care facilities. The primary certified nursing assistant was interviewed about R-REM. Advanced measurement methods were used to develop a measure of R-REM. Results: The loadings on the general factor for the final 11-item scale were greater than those on the group factor except for the item “other physical behavior” (0.63 vs. 0.74), suggesting essential unidimensionality. Although the bifactor model fit was slightly better than that of the unidimensional model, the difference was trivial (bifactor comparative fit index [CFI] = 0.997, root mean square error of approximation [RMSEA] = 0.013, unidimensional CFI = 0.979, and RMSEA = 0.030). However, modest support was provided for use of verbal and physical subscales. The explained common variance statistics were 0.76 for the bifactor model compared with 0.63 for the unidimensional model. Discussion: The development of this R-REM measure will help to advance the measurement and ultimately evaluation of interventions associated with this important and under recognized problem facing residents in long-term care settings. PMID:23448960

  1. Absolute Identification by Relative Judgment

    ERIC Educational Resources Information Center

    Stewart, Neil; Brown, Gordon D. A.; Chater, Nick

    2005-01-01

    In unidimensional absolute identification tasks, participants identify stimuli that vary along a single dimension. Performance is surprisingly poor compared with discrimination of the same stimuli. Existing models assume that identification is achieved using long-term representations of absolute magnitudes. The authors propose an alternative…

  2. Model-Based Collaborative Filtering Analysis of Student Response Data: Machine-Learning Item Response Theory

    ERIC Educational Resources Information Center

    Bergner, Yoav; Droschler, Stefan; Kortemeyer, Gerd; Rayyan, Saif; Seaton, Daniel; Pritchard, David E.

    2012-01-01

    We apply collaborative filtering (CF) to dichotomously scored student response data (right, wrong, or no interaction), finding optimal parameters for each student and item based on cross-validated prediction accuracy. The approach is naturally suited to comparing different models, both unidimensional and multidimensional in ability, including a…

  3. Ramsay Curve IRT for Likert-Type Data

    ERIC Educational Resources Information Center

    Woods, Carol M.

    2007-01-01

    Ramsay curve item response theory (RC-IRT) was recently developed to detect and correct for nonnormal latent variables when unidimensional IRT models are fitted to data using maximum marginal likelihood estimation. The purpose of this research is to evaluate the performance of RC-IRT for Likert-type item responses with varying test lengths, sample…

  4. Item Response Theory with Estimation of the Latent Density Using Davidian Curves

    ERIC Educational Resources Information Center

    Woods, Carol M.; Lin, Nan

    2009-01-01

    Davidian-curve item response theory (DC-IRT) is introduced, evaluated with simulations, and illustrated using data from the Schedule for Nonadaptive and Adaptive Personality Entitlement scale. DC-IRT is a method for fitting unidimensional IRT models with maximum marginal likelihood estimation, in which the latent density is estimated,…

  5. Ramsay-Curve Item Response Theory (RC-IRT) to Detect and Correct for Nonnormal Latent Variables

    ERIC Educational Resources Information Center

    Woods, Carol M.

    2006-01-01

    Popular methods for fitting unidimensional item response theory (IRT) models to data assume that the latent variable is normally distributed in the population of respondents, but this can be unreasonable for some variables. Ramsay-curve IRT (RC-IRT) was developed to detect and correct for this nonnormality. The primary aims of this article are to…

  6. Differential School Effectiveness in Relation to Sex and Social Class: Some Implications for Policy Evaluation

    ERIC Educational Resources Information Center

    Kyriakides, Leonidas

    2004-01-01

    This article reviews school effectiveness theory, concentrating on the unidimensionality of the school effect concept, and focuses on differential school effectiveness, by which is meant the capacity of the school to be effective with different groups of pupils. It presents findings from research exploring the associations between sex, social…

  7. The Factor Structure of the Work-Family Conflict Multidimensional Scale: Exploring the Expectations of College Students

    ERIC Educational Resources Information Center

    Gaffey, Abigail R.; Rottinghaus, Patrick J.

    2009-01-01

    Work-family conflict (WFC) has been examined from a unidimensional approach, yet recent research has revealed three types (i.e., time, strain, and behavior) and two directions of work-family conflict. Previous researchers suggested that college students are unable to discern between the multiple-facets of WFC, thus measured anticipated WFC…

  8. The Motivation of Stereotypic and Repetitive Behavior: Examination of Construct Validity of the Motivation Assessment Scale

    ERIC Educational Resources Information Center

    Joosten, Annette V.; Bundy, Anita C.

    2008-01-01

    Construct validity of the Motivation Assessment Scale (MAS) (Durand, Crimmins, The Motivation Assessment Scale 1988) was studied using Rasch analysis data from 67 children (246 MASs), with dual diagnosis of autism and intellectual disability or with intellectual disability only. Results failed to support the proposed unidimensional construct or…

  9. Evaluation of DTF and DIF in Two-Dimensional IRT.

    ERIC Educational Resources Information Center

    Oshima, T. C.; And Others

    In 1992 N. S. Raju and others proposed a general procedure for assessing differential test functioning (DTF) and item bias (differential item functioning or DIF) in tests developed with unidimensional, multidimensional, or polytomous item response theory (IRT) models. The purpose of this paper is to assess the adequacy and validity of their…

  10. Conditional Covariance-Based Subtest Selection for DIMTEST

    ERIC Educational Resources Information Center

    Froelich, Amy G.; Habing, Brian

    2008-01-01

    DIMTEST is a nonparametric hypothesis-testing procedure designed to test the assumptions of a unidimensional and locally independent item response theory model. Several previous Monte Carlo studies have found that using linear factor analysis to select the assessment subtest for DIMTEST results in a moderate to severe loss of power when the exam…

  11. Longitudinal Tests of Competing Factor Structures for the Rosenberg Self-Esteem Scale: Traits, Ephemeral Artifacts, and Stable Response Styles

    ERIC Educational Resources Information Center

    Marsh, Herbert W.; Scalas, L. Francesca; Nagengast, Benjamin

    2010-01-01

    Self-esteem, typically measured by the Rosenberg Self-Esteem Scale (RSE), is one of the most widely studied constructs in psychology. Nevertheless, there is broad agreement that a simple unidimensional factor model, consistent with the original design and typical application in applied research, does not provide an adequate explanation of RSE…

  12. Technical Analysis of Teacher Responses to the Self-Evaluation Scale-Teacher (SES-T) Version

    ERIC Educational Resources Information Center

    Erford, Bradley T.; Lowe, Samantha; Chang, Catherine Y.

    2011-01-01

    The Self-Evaluation Scale--Teacher version, used to assess teacher perceived self-esteem of students, was analyzed. A unidimensional model emerged from exploratory factor analysis, with cautious acceptance of data fit. Reliability and external aspects of validity were supported by the Self-Evaluation Scale--Teacher data.

  13. Comparing Categorization Models

    ERIC Educational Resources Information Center

    Rouder, Jeffrey N.; Ratcliff, Roger

    2004-01-01

    Four experiments are presented that competitively test rule- and exemplar-based models of human categorization behavior. Participants classified stimuli that varied on a unidimensional axis into 2 categories. The stimuli did not consistently belong to a category; instead, they were probabilistically assigned. By manipulating these assignment…

  14. Constant Latent Odds-Ratios Models and the Mantel-Haenszel Null Hypothesis

    ERIC Educational Resources Information Center

    Hessen, David J.

    2005-01-01

    In the present paper, a new family of item response theory (IRT) models for dichotomous item scores is proposed. Two basic assumptions define the most general model of this family. The first assumption is local independence of the item scores given a unidimensional latent trait. The second assumption is that the odds-ratios for all item-pairs are…

  15. Application of a General Polytomous Testlet Model to the Reading Section of a Large-Scale English Language Assessment. Research Report. ETS RR-10-21

    ERIC Educational Resources Information Center

    Li, Yanmei; Li, Shuhong; Wang, Lin

    2010-01-01

    Many standardized educational tests include groups of items based on a common stimulus, known as "testlets". Standard unidimensional item response theory (IRT) models are commonly used to model examinees' responses to testlet items. However, it is known that local dependence among testlet items can lead to biased item parameter estimates when…

  16. Personality Correlates of Aggression: Evidence from Measures of the Five-Factor Model, UPPS Model of Impulsivity, and BIS/BAS

    ERIC Educational Resources Information Center

    Miller, Joshua D.; Zeichner, Amos; Wilson, Lauren F.

    2012-01-01

    Although many studies of personality and aggression focus on multidimensional traits and higher order personality disorders (e.g., psychopathy), lower order, unidimensional traits may provide more precision in identifying specific aspects of personality that relate to aggression. The current study includes a comprehensive measurement of lower…

  17. Ramsay-Curve Item Response Theory for the Three-Parameter Logistic Item Response Model

    ERIC Educational Resources Information Center

    Woods, Carol M.

    2008-01-01

    In Ramsay-curve item response theory (RC-IRT), the latent variable distribution is estimated simultaneously with the item parameters of a unidimensional item response model using marginal maximum likelihood estimation. This study evaluates RC-IRT for the three-parameter logistic (3PL) model with comparisons to the normal model and to the empirical…

  18. Some Issues in Item Response Theory: Dimensionality Assessment and Models for Guessing

    ERIC Educational Resources Information Center

    Smith, Jessalyn

    2009-01-01

    Currently, standardized tests are widely used as a method to measure how well schools and students meet academic standards. As a result, measurement issues have become an increasingly popular topic of study. Unidimensional item response models are used to model latent abilities and specific item characteristics. This class of models makes…

  19. A Pearson-Type-VII Item Response Model for Assessing Person Fluctuation

    ERIC Educational Resources Information Center

    Ferrando, Pere J.

    2007-01-01

    Using Lumsden's Thurstonian fluctuation model as a starting point, this paper attempts to develop a unidimensional item response theory model intended for binary personality items. Under some additional assumptions, a new model is obtained in which the item characteristic curves are defined by a cumulative Pearson-Type-VII distribution, and the…

  20. A Preliminary Study for a New Model of Sense of Community

    ERIC Educational Resources Information Center

    Tartaglia, Stefano

    2006-01-01

    Although Sense of Community (SOC) is usually defined as a multidimensional construct, most SOC scales are unidimensional. To reduce the split between theory and empirical research, the present work identifies a multifactor structure for the Italian Sense of Community Scale (ISCS) that has already been validated as a unitary index of SOC. This…

  1. Is Lawson's Classroom Test of Formal Reasoning Valid?

    ERIC Educational Resources Information Center

    Pratt, C.; Hacker, R. G.

    1984-01-01

    A unidimensional latent trait model was used to test a single-factor hypothesis of the Lawson Classroom Test of Formal Reasoning. The test failed to provide a valid measure of formal reasoning. This was a result of test format which neglected aspects of formal reasoning emphasized by Inhelder and Piaget. (Author/DWH)

  2. Mokken Scale Analysis Using Hierarchical Clustering Procedures

    ERIC Educational Resources Information Center

    van Abswoude, Alexandra A. H.; Vermunt, Jeroen K.; Hemker, Bas T.; van der Ark, L. Andries

    2004-01-01

    Mokken scale analysis (MSA) can be used to assess and build unidimensional scales from an item pool that is sensitive to multiple dimensions. These scales satisfy a set of scaling conditions, one of which follows from the model of monotone homogeneity. An important drawback of the MSA program is that the sequential item selection and scale…

  3. A Rasch Analysis of the Academic Self-Concept Questionnaire

    ERIC Educational Resources Information Center

    Joyce, Tan Bei Yu; Yates, Shirley M.

    2007-01-01

    This study used the Rasch model to assess the unidimensionality and item-person fit of an Academic Self-Concept Questionnaire (ASCQ) that is based on the Confucian Heritage Culture (CHC) perspective. Knowledge of the relationship between academic achievement and academic self-concept is particularly useful because academic achievement is…

  4. Perceived Organizational Support: Further Evidence of Construct Validity.

    ERIC Educational Resources Information Center

    Hutchison, Steven

    1997-01-01

    Confirmatory factor analysis was used to examine the construct validity of scores from the Survey of Perceived Organizational Support (SPOS)(R. Eisenberger and others, 1986) using responses of 205 college faculty and staff members. Consistent with previous research, the SPOS was found to be unidimensional and distinguishable from two similarly…

  5. Concurrent Adaptive Measurement of Multiple Abilities.

    ERIC Educational Resources Information Center

    Ackerman, Terry A.; Davey, Tim C.

    An adaptive test can usually match or exceed the measurement precision of conventional tests several times its length. This increased efficiency is not without costs, however, as the models underlying adaptive testing make strong assumptions about examinees and items. Most troublesome is the assumption that item pools are unidimensional. Truly…

  6. Development and Psychometric Evaluation of the Personal Growth Initiative Scale-II

    ERIC Educational Resources Information Center

    Robitschek, Christine; Ashton, Matthew W.; Spering, Cynthia C.; Geiger, Nathaniel; Byers, Danielle; Schotts, G. Christian; Thoen, Megan A.

    2012-01-01

    The original Personal Growth Initiative Scale (PGIS; Robitschek, 1998) was unidimensional, despite theory identifying multiple components (e.g., cognition and behavior) of personal growth initiative (PGI). The present research developed a multidimensional measure of the complex process of PGI, while retaining the brief and psychometrically sound…

  7. Multidimensional Item Response Theory Models in Vocational Interest Measurement: An Illustration Using the AIST-R

    ERIC Educational Resources Information Center

    Wetzel, Eunike; Hell, Benedikt

    2014-01-01

    Vocational interest inventories are commonly analyzed using a unidimensional approach, that is, each subscale is analyzed separately. However, the theories on which these inventories are based often postulate specific relationships between the interest traits. This article presents a multidimensional approach to the analysis of vocational interest…

  8. Promise and Limits of Mentoring in Academic Science: A Look at Research on Impact and Effectiveness.

    ERIC Educational Resources Information Center

    Grant, Linda; Ward, Kathryn

    2000-01-01

    Considers the importance of mentoring in physical, chemical, and social sciences research. Discusses the mentoring program of the Association for Women in Science (AWIS) which focuses on helping women and minority scientists. Describes mentoring as "typically an asymmetrical power relation but it is not entirely unidimensional in flow of sources."…

  9. Verbal Behavior and Drive: A Theory in Crisis.

    ERIC Educational Resources Information Center

    Bradac, James J.; Elliot, Norman D.

    There is increasing debate over the unidimensionality of the construct "drive" in theories of behavior. The earliest drive theory postulated a simple entity which increased or decreased as a function of external or internal stimulation and affected behavior monotonically. Duffy and Malmo have recently hypothesized that the effects of drive are not…

  10. Dimensionality in the Similarity Judgments of Young Children.

    ERIC Educational Resources Information Center

    Fahrmeier, Edward D.; Medin, Douglas L.

    In order to examine the nature of dimensional processing in children, 20 kindergarten and 20 third grade Chinese-American children were asked to make similarity judgments for unidimensional sets of stimuli differing in color (hue), size, and shape, respectively. Age differences were generally confined to the color set. The judgments of the older…

  11. Can Education Be Made "Intrinsically Interesting" to Children?

    ERIC Educational Resources Information Center

    Condry, John; Koslowski, Barbara

    This paper reviews the role of intrinsic and extrinsic motivation in children's learning. The paper contends that two types of learning exist: self-initiated learning which is intrinsically motivated, and learning initiated by another person which involves external rewards. The paper suggests that motivation is not unidimensional and that task…

  12. Assessing the Dimensionality of Polytomous Item Responses with Small Sample Sizes and Short Test Lengths: A Comparison of Procedures.

    ERIC Educational Resources Information Center

    De Champlain, Andre F.; Gessaroli, Marc E.; Tang, K. Linda; De Champlain, Judy E.

    The empirical Type I error rates of Poly-DIMTEST (H. Li and W. Stout, 1995) and the LISREL8 chi square fit statistic (K. Joreskog and D. Sorbom, 1993) were compared with polytomous unidimensional data sets simulated to vary as a function of test length and sample size. The rejection rates for both statistics were also studied with two-dimensional…

  13. Structural Robustness and Ability Estimation in Item Response Theory: A Survey.

    ERIC Educational Resources Information Center

    Junker, Brian W.; And Others

    Some item response theory (IRT) techniques work in applications even though the usual structural IRT assumptions, and local independence (LI) in particular, do not hold. When the departure from LI is too great, traditional procedures will break down. Although violations of strictly unidimensional, monotone, locally independent latent structure can…

  14. A Comparison of Responses on the Attitudes toward Women Scale and Attitudes toward Feminism Scale: Is There a Difference between College-Age and Later-Life Adults with the Original Norms?

    ERIC Educational Resources Information Center

    Byrne, Zinta S.; Felker, Sydney; Vacha-Haase, Tammi; Rickard, Kathryn M.

    2011-01-01

    Responses from college-age students and those 50 years and older were compared using the Attitudes Toward Women Scale and the Attitudes Toward Feminism Scale. Results from a multigroup confirmatory factor analysis showed groups differed on each scale, suggesting unidimensional scales no longer represent attitudes toward women or feminism.…

  15. Robustness of Hierarchical Modeling of Skill Association in Cognitive Diagnosis Models

    ERIC Educational Resources Information Center

    Templin, Jonathan L.; Henson, Robert A.; Templin, Sara E.; Roussos, Louis

    2008-01-01

    Several types of parameterizations of attribute correlations in cognitive diagnosis models use the reduced reparameterized unified model. The general approach presumes an unconstrained correlation matrix with K(K - 1)/2 parameters, whereas the higher order approach postulates K parameters, imposing a unidimensional structure on the correlation…

  16. Educational Mismatch of Graduates: A Multidimensional and Fuzzy Indicator

    ERIC Educational Resources Information Center

    Betti, Gianni; D'Agostino, Antonella; Neri, Laura

    2011-01-01

    In this paper we attempt to measure the educational mismatch, seen as a problem of overeducation, using a multidimensional and fuzzy methodology. Educational mismatch can be difficult to measure because many factors can converge to its definition and the traditional unidimensional indicators presented in literature can offer a restricted view of…

  17. Fitting the Mixed Rasch Model to a Reading Comprehension Test: Identifying Reader Types

    ERIC Educational Resources Information Center

    Baghaei, Purya; Carstensen, Claus H.

    2013-01-01

    Standard unidimensional Rasch models assume that persons with the same ability parameters are comparable. That is, the same interpretation applies to persons with identical ability estimates as regards the underlying mental processes triggered by the test. However, research in cognitive psychology shows that persons at the same trait level may…

  18. Investigating the Psychometric Properties of School Counselor Self-Advocacy Questionnaire

    ERIC Educational Resources Information Center

    Clemens, Elysia V.; Shipp, Adria; Kimbel, Tyler

    2011-01-01

    This article reports on the development and the exploration of the underlying psychometric properties of the School Counselor Self-Advocacy Questionnaire, a measure of skills school counselors can use to advocate for their roles and programs. An exploratory factor analysis (N = 188) suggested a unidimensional model, and a confirmatory factor…

  19. The Relational Health Indices: Reanalysis of a Measure of Relational Quality

    ERIC Educational Resources Information Center

    Frey, Lisa L.; Beesley, Denise; Newman, Jody L.

    2005-01-01

    The study examined the component structure of the Relational Health Indices (B. Liang et al., 2002) with a mixed-sex sample of students seeking services at a university counseling center. In contrast to previous findings, results suggested a unidimensional structure for the peer and mentor composites and a 2-component structure for the community…

  20. Interval Estimation of Revision Effect on Scale Reliability via Covariance Structure Modeling

    ERIC Educational Resources Information Center

    Raykov, Tenko

    2009-01-01

    A didactic discussion of a procedure for interval estimation of change in scale reliability due to revision is provided, which is developed within the framework of covariance structure modeling. The method yields ranges of plausible values for the population gain or loss in reliability of unidimensional composites, which results from deletion or…

  1. Multidimensional CAT Item Selection Methods for Domain Scores and Composite Scores: Theory and Applications

    ERIC Educational Resources Information Center

    Yao, Lihua

    2012-01-01

    Multidimensional computer adaptive testing (MCAT) can provide higher precision and reliability or reduce test length when compared with unidimensional CAT or with the paper-and-pencil test. This study compared five item selection procedures in the MCAT framework for both domain scores and overall scores through simulation by varying the structure…

  2. Alphabet Knowledge in Preschool: A Rasch Model Analysis

    ERIC Educational Resources Information Center

    Drouin, Michelle; Horner, Sherri L.; Sondergeld, Toni A.

    2012-01-01

    In this study, we used Rasch model analyses to examine (1) the unidimensionality of the alphabet knowledge construct and (2) the relative difficulty of different alphabet knowledge tasks (uppercase letter recognition, names, and sounds, and lowercase letter names) within a sample of preschoolers (n=335). Rasch analysis showed that the four…

  3. Development and Initial Validation of the Inventory of Microaggressions against Black Individuals

    ERIC Educational Resources Information Center

    Mercer, Sterett H.; Zeigler-Hill, Virgil; Wallace, Marion; Hayes, DeMarquis M.

    2011-01-01

    The present article describes the development and initial validation of the Inventory of Microaggressions Against Black Individuals (IMABI) using a sample of 385 undergraduates who self-identified as Black or African American. The IMABI is a 14-item, unidimensional measure of racial microaggressions that captures both microinsults and…

  4. Cognitive Correlates of Math Skills in Third-Grade Students

    ERIC Educational Resources Information Center

    Mannamaa, Mairi; Kikas, Eve; Peets, Katlin; Palu, Anu

    2012-01-01

    Math achievement is not a unidimensional construct but includes different skills that require different cognitive abilities. The focus of this study was to examine associations between a number of cognitive abilities and three domains of math skills (knowing, applying and problem solving) simultaneously in a multivariate framework. Participants…

  5. Impact of Diagnosticity on the Adequacy of Models for Cognitive Diagnosis under a Linear Attribute Structure: A Simulation Study

    ERIC Educational Resources Information Center

    de La Torre, Jimmy; Karelitz, Tzur M.

    2009-01-01

    Compared to unidimensional item response models (IRMs), cognitive diagnostic models (CDMs) based on latent classes represent examinees' knowledge and item requirements using discrete structures. This study systematically examines the viability of retrofitting CDMs to IRM-based data with a linear attribute structure. The study utilizes a procedure…

  6. Checking Dimensionality in Item Response Models with Principal Component Analysis on Standardized Residuals

    ERIC Educational Resources Information Center

    Chou, Yeh-Tai; Wang, Wen-Chung

    2010-01-01

    Dimensionality is an important assumption in item response theory (IRT). Principal component analysis on standardized residuals has been used to check dimensionality, especially under the family of Rasch models. It has been suggested that an eigenvalue greater than 1.5 for the first eigenvalue signifies a violation of unidimensionality when there…

  7. Motivational Correlates of Portuguese High Schoolers' Vocational Identity: Cultural Validation of the Goal Instability Scale

    ERIC Educational Resources Information Center

    Santos, Paulo Jorge; Casillas, Alex; Robbins, Steven B.

    2004-01-01

    This study examined the relevance of the Goal Instability Scale-Portuguese Adaptation (GIS-P) on the vocational identity and career certainty of 375 10th-, 11th-, and 12th-grade Portuguese high schoolers. After translating the GIS-P, confirmatory factor analysis was used to examine the factorial unidimensionality and reliability of the construct.…

  8. Item Analysis of the Paper Folding Test (Wks. 622). Technical Report No. 1988-6.

    ERIC Educational Resources Information Center

    Wothke, Werner; Zimowski, Michele F.

    Large-sample item response data for the 10-item Paper Folding worksample 622 (N=2,749) and for five new experimental paper folding items (N=2,514) are analyzed with the logistic item response model and with full-information item factor analysis. The main results of the unidimensional analysis are that: (1) item discrimination is heterogeneous, so…

  9. Measuring Adolescent Life Satisfaction: Psychometric Properties of the Satisfaction With Life Scale in a Sample of Italian Adolescents and Young Adults

    ERIC Educational Resources Information Center

    Di Fabio, Annamaria; Gori, Alessio

    2016-01-01

    This study examined the factor structure and the psychometric properties of the Satisfaction With Life Scale (SWLS) in a sample of 1,515 Italian (females = 60.26%, males = 39.74%) adolescents and young adults (M[subscript age] = 17.6 years, SD = 1.21). Results confirmed the unidimensionality, good reliability, and concurrent validity of the…

  10. Integration of Impulsivity and Positive Mood to Predict Risky Behavior: Development and Validation of a Measure of Positive Urgency

    ERIC Educational Resources Information Center

    Cyders, Melissa A.; Smith, Gregory T.; Spillane, Nichea S.; Fischer, Sarah; Annus, Agnes M.; Peterson, Claire

    2007-01-01

    In 3 studies, the authors developed and began to validate a measure of the propensity to act rashly in response to positive affective states (positive urgency). In Study 1, they developed a content-valid 14-item scale, showed that the measure was unidimensional, and showed that positive urgency was distinct from impulsivity-like constructs…