Improving comprehension in adolescents with severe receptive language impairments: a randomized control trial of intervention for coordinating conjunctions.

PubMed

Ebbels, Susan H; Marić, Nataša; Murphy, Aoife; Turner, Gail

2014-01-01

Little evidence exists for the effectiveness of therapy for children with receptive language difficulties, particularly those whose difficulties are severe and persistent. To establish the effectiveness of explicit speech and language therapy with visual support for secondary school-aged children with language impairments focusing on comprehension of coordinating conjunctions in a randomized control trial with an assessor blind to group status. Fourteen participants (aged 11;3-16;1) with severe RELI (mean standard scores: CELF4 ELS = 48, CELF4 RLS = 53 and TROG-2 = 57), but higher non-verbal (Matrices = 83) and visual perceptual skills (Test of Visual Perceptual Skills (TVPS) = 86) were randomly assigned to two groups: therapy versus waiting controls. In Phase 1, the therapy group received eight 30-min individual sessions of explicit teaching with visual support (Shape Coding) with their usual SLT. In Phase 2, the waiting controls received the same therapy. The participants' comprehension was tested pre-, post-Phase 1 and post-Phase 2 therapy on (1) a specific test of the targeted conjunctions, (2) the TROG-2 and (3) a test of passives. After Phase 1, the therapy group showed significantly more progress than the waiting controls on the targeted conjunctions (d = 1.6) and overall TROG-2 standard score (d = 1.4). The two groups did not differ on the passives test. After Phase 2, the waiting controls made similar progress to those in the original therapy group, who maintained their previous progress. Neither group showed progress on passives. When the two groups were combined, significant progress was found on the specific conjunctions (d = 1.3) and TROG-2 raw (d = 1.1) and standard scores (d = 0.9). Correlations showed no measures taken (including Matrices and TVPS) correlated significantly with progress on the targeted conjunctions or the TROG-2. Four hours of Shape Coding therapy led to significant gains on comprehension of coordinating conjunctions which were maintained after 4 months. Given the significant progress at a group level and the lack of reliable predictors of progress, this approach could be offered to other children with similar difficulties to the participants. However, the intervention was delivered one-to-one by speech and language therapists, thus the effectiveness of this therapy method with other methods of delivery remains to be evaluated. © 2013 Royal College of Speech and Language Therapists.

Cognitive ability of preschool, primary and secondary school children in Costa Rica.

PubMed

Rindermann, Heiner; Stiegmaier, Eva-Maria; Meisenberg, Gerhard

2015-05-01

Cognitive abilities of children in Costa Rica and Austria were compared using three age groups (N = 385/366). Cognitive ability tests (mental speed, culture reduced/fluid intelligence, literacy/crystallized intelligence) were applied that differed in the extent to which they refer to school-related knowledge. Preschool children (kindergarten, 5-6 years old, N(CR) = 80, N(Au) = 51) were assessed with the Coloured Progressive Matrices (CPM), primary school children (4th grade, 9-11 years old, N(CR) = 71, N(Au) = 71) with ZVT (a trail-making test), Standard Progressive Matrices (SPM) and items from PIRLS-Reading and TIMSS-Mathematics, and secondary school students (15-16 years old, N(CR) = 48, N(Au) = 48) with ZVT, Advanced Progressive Matrices (APM) and items from PISA-Reading and PISA-Mathematics. Additionally, parents and pupils were given questionnaires covering family characteristics and instruction. Average cognitive abilities were higher in Austria (Greenwich-IQ M(CR) = 87 and M(Au) = 99, d(IQ) = 12 points) and differences were smaller in preschool than in secondary school (d(IQ) = 7 vs 20 points). Differences in crystallized intelligence were larger than in fluid intelligence (mental speed: d(IQ) = 12, Raven: d(IQ) = 10, student achievement tests: d(IQ) = 17 IQ points). Differences were larger in comparisons at the level of g-factors. Austrian children were also taller (6.80 cm, d = 1.07 SD), but had lower body mass index (BMI(CR) = 19.35 vs BMI(Au) = 17.59, d = -0.89 SD). Different causal hypotheses explaining these differences are compared.

Raven's Coloured Progressive Matrices as a Measure of Cognitive Functioning in Cerebral Palsy

ERIC Educational Resources Information Center

Pueyo, R.; Junque, C.; Vendrell, P.; Narberhaus, A.; Segarra, D.

2008-01-01

Background: Cognitive dysfunction is frequent in Cerebral Palsy (CP). CP motor impairment and associated speech deficits often hinder cognitive assessment, with the result being that not all CP studies consider cognitive dysfunction. Raven's Coloured Progressive Matrices is a simple, rapid test which can be used in persons with severe motor…

An Examination of Ethnic and Gender Differences in the Raven Coloured Progressive Matrices Test.

ERIC Educational Resources Information Center

Kluever, Raymond C.; Green, Kathy E.

Response patterns to the Raven Coloured Progressive Matrices (CPM) were analyzed for a sample of 203 Hispanic and 254 Anglo first- through fifth-grade children from a rural school district in southern Colorado. Gender distributions were nearly equal. Gender and ethnic differences were examined within the context of determining whether the CPM…

Validating Alternative Modes of Scoring for Coloured Progressive Matrices.

ERIC Educational Resources Information Center

Razel, Micha; Eylon, Bat-Sheva

Conventional scoring of the Coloured Progressive Matrices (CPM) was compared with three methods of multiple weight scoring. The methods include: (1) theoretical weighting in which the weights were based on a theory of cognitive processing; (2) judged weighting in which the weights were given by a group of nine adult expert judges; and (3)…

The WISC-III and Raven Coloured Progressive Matrices Test: A Pilot Study of Relationships.

ERIC Educational Resources Information Center

Kluever, Raymond C.; And Others

The relationship between scores on Raven's Coloured Progressive Matrices (CPM) scores and subtest scores and IQs from the Wechsler Intelligence Scale for Children-III (WISC-III) was studied for 28 children aged 6 to 11 years. Subjects had been referred to a university assessment center because they were believed to have exceptional learning…

Reliability of the Raven Coloured Progressive Matrices for Anglo and for Mexican-American Children.

ERIC Educational Resources Information Center

Valencia, Richard R.

1984-01-01

Investigated the internal consistency reliability estimates of the Raven Coloured Progressive Matrices (CPM) for 96 Anglo and Mexican American third-grade boys from low socioeconomic status background. The results showed that the reliability estimates of the CPM for the two ethnic groups were acceptably high and extremely similar in magnitude.…

Researchers' Bibliography for Raven's Progressive Matrices and Mill Hill Vocabulary Scales.

ERIC Educational Resources Information Center

Court, J. H., Comp.

This annotated bibliography enables researchers who are using Raven's Progressive Matrices or the Mill Hill Vocabulary Scales to become familiar with other work that used these tests. The bibliography derives from Raven's own collection of sources, updated to the end of 1971. The major division of material is by tests rather than subject areas;…

New Rule Use Drives the Relation between Working Memory Capacity and Raven's Advanced Progressive Matrices

ERIC Educational Resources Information Center

Wiley, Jennifer; Jarosz, Andrew F.; Cushen, Patrick J.; Colflesh, Gregory J. H.

2011-01-01

The correlation between individual differences in working memory capacity and performance on the Raven's Advanced Progressive Matrices (RAPM) is well documented yet poorly understood. The present work proposes a new explanation: that the need to use a new combination of rules on RAPM problems drives the relation between performance and working…

Item and Error Analysis on Raven's Coloured Progressive Matrices in Williams Syndrome

ERIC Educational Resources Information Center

Van Herwegen, Jo; Farran, Emily; Annaz, Dagmara

2011-01-01

Raven's Coloured Progressive Matrices (RCPM) is a standardised test that is commonly used to obtain a non-verbal reasoning score for children. As the RCPM involves the matching of a target to a pattern it is also considered to be a visuo-spatial perception task. RCPM is therefore frequently used in studies in Williams Syndrome (WS), in order to…

Concurrent and Predictive Validity of the Raven Progressive Matrices and the Naglieri Nonverbal Ability Test

ERIC Educational Resources Information Center

Balboni, Giulia; Naglieri, Jack A.; Cubelli, Roberto

2010-01-01

The concurrent and predictive validities of the Naglieri Nonverbal Ability Test (NNAT) and Raven's Colored Progressive Matrices (CPM) were investigated in a large group of Italian third-and fifth-grade students with different sociocultural levels evaluated at the beginning and end of the school year. CPM and NNAT scores were related to math and…

A Comparison between Element Salience versus Context as Item Difficulty Factors in Raven's Matrices

ERIC Educational Resources Information Center

Perez-Salas, Claudia P.; Streiner, David L.; Roberts, Maxwell J.

2012-01-01

The nature of contextual facilitation effects for items derived from Raven's Progressive Matrices was investigated in two experiments. For these, the original matrices were modified, creating either abstract versions with high element salience, or versions which comprised realistic entities set in familiar contexts. In order to replicate and…

The Quest for Item Types Based on Information Processing: An Analysis of Raven's Advanced Progressive Matrices, with a Consideration of Gender Differences

ERIC Educational Resources Information Center

Vigneau, Francois; Bors, Douglas A.

2008-01-01

Various taxonomies of Raven's Advanced Progressive Matrices (APM) items have been proposed in the literature to account for performance on the test. In the present article, three such taxonomies based on information processing, namely Carpenter, Just and Shell's [Carpenter, P.A., Just, M.A., & Shell, P., (1990). What one intelligence test…

Reliability of the Raven Colored Progressive Matrices Test: Age and Ethnic Group Comparisons.

ERIC Educational Resources Information Center

Carlson, Jerry S.; Jensen, C. Mark

1981-01-01

Reliabilities for the Raven Colored Progressive Matrices Test (CPM) are reported for three age groups (ages 5 1/2- 6 1/2, 6 1/2-7 1/2, and 7 1/2-8 1/2 years) and three ethnic groups (Anglo, Black, and Hispanic). Results indicate CPM is not equally reliable for all age groups, but appears equally reliable for the three ethnic groups. (Author)

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…

Matrix Summaries Improve Research Reports: Secondary Analyses Using Published Literature

ERIC Educational Resources Information Center

Zientek, Linda Reichwein; Thompson, Bruce

2009-01-01

Correlation matrices and standard deviations are the building blocks of many of the commonly conducted analyses in published research, and AERA and APA reporting standards recommend their inclusion when reporting research results. The authors argue that the inclusion of correlation/covariance matrices, standard deviations, and means can enhance…

Reliability and Validity Study for the Coloured Progressive Matrices Test between the Ages of 3-9 for Determining Gifted Children in the Pre-School Period

ERIC Educational Resources Information Center

Bildiren, Ahmet

2017-01-01

The objective of the study was to test the Coloured Progressive Matrices Test with regard to reliability and validity for the 3-9 age sample group because of the lack of diagnostic tools for the pre-school period. The sample group of the study was comprised of a total of 925 children with 433 girls (46.8%) and 492 boys (53.2%). Coloured…

Standards application and development plan for solar thermal technologies

NASA Astrophysics Data System (ADS)

Cobb, H. R. W.

1981-07-01

Functional and standards matrices, developed from input from ST users and from the industry that will be continually reviewed and updated as commercial aspects develop are presented. The matrices highlight codes, standards, test methods, functions and definitions that need to be developed. They will be submitted through ANSI for development by national consensus bodies. A contingency action is proposed for standards development if specific input is lacking at the committee level or if early development of a standard would hasten commercialization or gain needed jurisdictional acceptance.

Fungible Correlation Matrices: A Method for Generating Nonsingular, Singular, and Improper Correlation Matrices for Monte Carlo Research.

PubMed

Waller, Niels G

2016-01-01

For a fixed set of standardized regression coefficients and a fixed coefficient of determination (R-squared), an infinite number of predictor correlation matrices will satisfy the implied quadratic form. I call such matrices fungible correlation matrices. In this article, I describe an algorithm for generating positive definite (PD), positive semidefinite (PSD), or indefinite (ID) fungible correlation matrices that have a random or fixed smallest eigenvalue. The underlying equations of this algorithm are reviewed from both algebraic and geometric perspectives. Two simulation studies illustrate that fungible correlation matrices can be profitably used in Monte Carlo research. The first study uses PD fungible correlation matrices to compare penalized regression algorithms. The second study uses ID fungible correlation matrices to compare matrix-smoothing algorithms. R code for generating fungible correlation matrices is presented in the supplemental materials.

Enhancing Understanding of Transformation Matrices

ERIC Educational Resources Information Center

Dick, Jonathan; Childrey, Maria

2012-01-01

With the Common Core State Standards' emphasis on transformations, teachers need a variety of approaches to increase student understanding. Teaching matrix transformations by focusing on row vectors gives students tools to create matrices to perform transformations. This empowerment opens many doors: Students are able to create the matrices for…

Advanced Progressive Matrices and Sex Differences: Comment to Mackintosh and Bennett (2005)

ERIC Educational Resources Information Center

Colom, Roberto; Abad, Francisco J.

2007-01-01

Mackintosh and Bennett's [Mackintosh, N. J. and Bennett, E. S, (2005). ''What do Raven's Matrices measure? An analysis in terms of sex differences.'' Intelligence 33: 663-674.] study shows that males outperform females in some APM items but not in others, implicating that these items are measuring discriminable mental processes. The present…

Differential Effects of Intelligence, Perceptual Speed and Age on Growth in Attentional Speed and Accuracy

ERIC Educational Resources Information Center

Goldhammer, Frank; Rauch, Wolfgang A.; Schweizer, Karl; Moosbrugger, Helfried

2010-01-01

The study investigates the effects of intelligence, perceptual speed and age on intraindividual growth in attentional speed and attentional accuracy over the course of a 6-minute testing session. A sample of 193 subjects completed the Advanced Progressive Matrices and the Vienna Matrices Test representing intelligence, the tests Alertness and…

SLOCC classification of n qubits invoking the proportional relationships for spectrums and standard Jordan normal forms

NASA Astrophysics Data System (ADS)

Li, Dafa

2018-01-01

We investigate the proportional relationships for spectrums and standard Jordan normal forms (SJNFs) of the 4 by 4 matrices constructed from coefficient matrices of two SLOCC (stochastic local operations and classical communication) equivalent states of n qubits. The proportional relationships permit a reduction of SLOCC classification of n (≥ 4) qubits to a classification of 4 by 4 complex matrices. Invoking the proportional relationships for spectrums and SJNFs, pure states of n (≥ 4) qubits are partitioned into 12 groups or less and 34 families or less under SLOCC, respectively. Specially, it is true for four qubits.

Impact of breastfeeding on the intelligence quotient of eight-year-old children.

PubMed

Fonseca, Ana L M; Albernaz, Elaine P; Kaufmann, Cristina C; Neves, Ivana H; Figueiredo, Vera L M de

2013-01-01

This study aimed to determine the influence of breastfeeding on the intellectual capacity of children from a cohort in a developing country, with a control for the main confounding factors. A prospective cohort study was performed including all infants born in the hospitals of a medium-size city, and a random sample of these newborns was monitored at 30, 90, and 180 days of life, and at age 8 years. Several aspects of breastfeeding were assessed in the follow-up and, at 8 years, general intellectual capacity was assessed through the Raven's Colored Progressive Matrices test. The statistical analyses used Student's t-test, ANOVA, and linear regression and logistics, considering p-values less than 0.05 as statistically significant associations. At age 8 years, 560 children were assessed with Raven's Colored Progressive Matrices test. The average score was 22.56 points, with a standard deviation of 5.93. The difference in the averages found between the breastfed and non-breastfed groups at six months of age was 1.33 (p=0.008). Mother's and child's skin color, social and economic class, maternal education and smoking, and breastfeeding at six months of age (p=0.007) were still associated with the outcome. Children that were breastfed for six months or more had better performance in the general intellectual assessment, even after adjusting for the main confounding factors. Copyright © 2013 Sociedade Brasileira de Pediatria. Published by Elsevier Editora Ltda. All rights reserved.

Use of Mueller and non-Mueller matrices to describe polarization properties of telescope-based polarimeters

NASA Astrophysics Data System (ADS)

Seagraves, P. H.; Elmore, David F.

1994-09-01

Systems using optical elements such as linear polarizers, retarders, and mirrors can be represented by Mueller matrices. Some polarimeters include elements with time-varying polarization properties, multiple light beams, light detectors, and signal processing equipment. Standard Mueller matrix forms describing time-varying retarders, and beam splitters are presented, as well as non-Mueller matrices which describe detection and signal processing. These matrices provide a compact and intuitive mathematical description of polarimeter response which can aid in the refining of instrument designs.

Visual/Verbal-Analytic Reasoning Bias as a Function of Self-Reported Autistic-Like Traits: A Study of Typically Developing Individuals Solving Raven's Advanced Progressive Matrices

ERIC Educational Resources Information Center

Fugard, Andrew J. B.; Stewart, Mary E.; Stenning, Keith

2011-01-01

People with autism spectrum condition (ASC) perform well on Raven's matrices, a test which loads highly on the general factor in intelligence. However, the mechanisms supporting enhanced performance on the test are poorly understood. Evidence is accumulating that milder variants of the ASC phenotype are present in typically developing individuals,…

Mathematical foundations of the GraphBLAS

DOE PAGES

Kepner, Jeremy; Aaltonen, Peter; Bader, David; ...

2016-12-01

The GraphBLAS standard (GraphBlas.org) is being developed to bring the potential of matrix-based graph algorithms to the broadest possible audience. Mathematically, the GraphBLAS defines a core set of matrix-based graph operations that can be used to implement a wide class of graph algorithms in a wide range of programming environments. This study provides an introduction to the mathematics of the GraphBLAS. Graphs represent connections between vertices with edges. Matrices can represent a wide range of graphs using adjacency matrices or incidence matrices. Adjacency matrices are often easier to analyze while incidence matrices are often better for representing data. Fortunately, themore » two are easily connected by matrix multiplication. A key feature of matrix mathematics is that a very small number of matrix operations can be used to manipulate a very wide range of graphs. This composability of a small number of operations is the foundation of the GraphBLAS. A standard such as the GraphBLAS can only be effective if it has low performance overhead. Finally, performance measurements of prototype GraphBLAS implementations indicate that the overhead is low.« less

The growth of IQ among Estonian schoolchildren from ages 7 to 19.

PubMed

Pullmann, Helle; Allik, Jüri; Lynn, Richard

2004-11-01

The Standard Progressive Matrices test was standardized in Estonia on a representative sample of 4874 schoolchildren aged from 7 to 19 years. When the IQ of Estonian children was expressed in relation to British and Icelandic norms, both demonstrated a similar sigmoid relationship. The youngest Estonian group scored higher than the British and Icelandic norms: after first grade, the score fell below 100 and remained lower until age 12, and after that age it increased above the mean level of these two comparison countries. The difference between the junior school children and the secondary school children may be due to schooling, sampling error or different trajectories of intellectual maturation in different populations. Systematic differences in the growth pattern suggest that the development of intellectual capacities proceeds at different rates and the maturation process can take longer in some populations than in others.

Resampling-based Methods in Single and Multiple Testing for Equality of Covariance/Correlation Matrices

PubMed Central

Yang, Yang; DeGruttola, Victor

2016-01-01

Traditional resampling-based tests for homogeneity in covariance matrices across multiple groups resample residuals, that is, data centered by group means. These residuals do not share the same second moments when the null hypothesis is false, which makes them difficult to use in the setting of multiple testing. An alternative approach is to resample standardized residuals, data centered by group sample means and standardized by group sample covariance matrices. This approach, however, has been observed to inflate type I error when sample size is small or data are generated from heavy-tailed distributions. We propose to improve this approach by using robust estimation for the first and second moments. We discuss two statistics: the Bartlett statistic and a statistic based on eigen-decomposition of sample covariance matrices. Both statistics can be expressed in terms of standardized errors under the null hypothesis. These methods are extended to test homogeneity in correlation matrices. Using simulation studies, we demonstrate that the robust resampling approach provides comparable or superior performance, relative to traditional approaches, for single testing and reasonable performance for multiple testing. The proposed methods are applied to data collected in an HIV vaccine trial to investigate possible determinants, including vaccine status, vaccine-induced immune response level and viral genotype, of unusual correlation pattern between HIV viral load and CD4 count in newly infected patients. PMID:22740584

Resampling-based methods in single and multiple testing for equality of covariance/correlation matrices.

PubMed

Yang, Yang; DeGruttola, Victor

2012-06-22

Traditional resampling-based tests for homogeneity in covariance matrices across multiple groups resample residuals, that is, data centered by group means. These residuals do not share the same second moments when the null hypothesis is false, which makes them difficult to use in the setting of multiple testing. An alternative approach is to resample standardized residuals, data centered by group sample means and standardized by group sample covariance matrices. This approach, however, has been observed to inflate type I error when sample size is small or data are generated from heavy-tailed distributions. We propose to improve this approach by using robust estimation for the first and second moments. We discuss two statistics: the Bartlett statistic and a statistic based on eigen-decomposition of sample covariance matrices. Both statistics can be expressed in terms of standardized errors under the null hypothesis. These methods are extended to test homogeneity in correlation matrices. Using simulation studies, we demonstrate that the robust resampling approach provides comparable or superior performance, relative to traditional approaches, for single testing and reasonable performance for multiple testing. The proposed methods are applied to data collected in an HIV vaccine trial to investigate possible determinants, including vaccine status, vaccine-induced immune response level and viral genotype, of unusual correlation pattern between HIV viral load and CD4 count in newly infected patients.

Central Limit Theorems for Linear Statistics of Heavy Tailed Random Matrices

NASA Astrophysics Data System (ADS)

Benaych-Georges, Florent; Guionnet, Alice; Male, Camille

2014-07-01

We show central limit theorems (CLT) for the linear statistics of symmetric matrices with independent heavy tailed entries, including entries in the domain of attraction of α-stable laws and entries with moments exploding with the dimension, as in the adjacency matrices of Erdös-Rényi graphs. For the second model, we also prove a central limit theorem of the moments of its empirical eigenvalues distribution. The limit laws are Gaussian, but unlike the case of standard Wigner matrices, the normalization is the one of the classical CLT for independent random variables.

Electrospun Poly(lactic acid-co-glycolic acid) Scaffolds for Skin Tissue Engineering

PubMed Central

Kumbar, Sangamesh G.; Nukavarapu, Syam Prasad; James, Roshan; Nair, Lakshmi S.; Laurencin, Cato T.

2008-01-01

Electrospun fiber matrices composed of scaffolds of varying fiber diameters were investigated for potential application of severe skin loss. Few systematic studies have been performed to examine the effect of varying fiber diameter electrospun fiber matrices for skin regeneration. The present study reports the fabrication of poly[lactic acid-co-glycolic acid] (PLAGA) matrices with fiber diameters of 150–225, 200–300, 250–467, 500–900, 600–1200, 2500–3000 and 3250–6000 nm via electrospinning. All fiber matrices found to have a tensile modulus from 39.23 ± 8.15 to 79.21 ± 13.71 MPa which falls in the range for normal human skin. Further, the porous fiber matrices have porosity between 38–60 % and average pore diameters between 10–14µm. We evaluated the efficacy of these biodegradable fiber matrices as skin substitutes by seeding them with human skin fibroblasts (hSF). Human skin fibroblasts acquired a well spread morphology and showed significant progressive growth on fiber matrices in the 350–1100 nm diameter range. Collagen type III gene expression was significantly up-regulated in hSF seeded on matrices with fiber diameters in the range of 350–1100 nm. Based on the need, the proposed fiber skin substitutes can be successfully fabricated and optimized for skin fibroblast attachment and growth. PMID:18639927

Engineered decellularized matrices to instruct bone regeneration processes.

PubMed

Papadimitropoulos, Adam; Scotti, Celeste; Bourgine, Paul; Scherberich, Arnaud; Martin, Ivan

2015-01-01

Despite the significant progress in the field of bone tissue engineering, cell-based products have not yet reached the stage of clinical adoption. This is due to the uncertain advantages from the standard-of-care, combined with challenging cost-and regulatory-related issues. Novel therapeutic approaches could be based on exploitation of the intrinsic regenerative capacity of bone tissue, provided the development of a deeper understanding of its healing mechanisms. While it is well-established that endogenous progenitors can be activated toward bone formation by overdoses of single morphogens, the challenge to stimulate the healing processes by coordinated and controlled stimulation of specific cell populations remains open. Here, we review the recent approaches to generate osteoinductive materials based on the use of decellularized extracellular matrices (ECM) as reservoirs of multiple factors presented at physiological doses and through the appropriate ligands. We then propose the generation of customized engineered and decellularized ECM (i) as a tool to better understand the processes of bone regeneration and (ii) as safe and effective "off-the-shelf" bone grafts for clinical use. This article is part of a Special Issue entitled Stem Cells and Bone. Copyright © 2014 Elsevier Inc. All rights reserved.

Examination of various roles for covariance matrices in the development, evaluation, and application of nuclear data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, D.L.

The last decade has been a period of rapid development in the implementation of covariance-matrix methodology in nuclear data research. This paper offers some perspective on the progress which has been made, on some of the unresolved problems, and on the potential yet to be realized. These discussions address a variety of issues related to the development of nuclear data. Topics examined are: the importance of designing and conducting experiments so that error information is conveniently generated; the procedures for identifying error sources and quantifying their magnitudes and correlations; the combination of errors; the importance of consistent and well-characterized measurementmore » standards; the role of covariances in data parameterization (fitting); the estimation of covariances for values calculated from mathematical models; the identification of abnormalities in covariance matrices and the analysis of their consequences; the problems encountered in representing covariance information in evaluated files; the role of covariances in the weighting of diverse data sets; the comparison of various evaluations; the influence of primary-data covariance in the analysis of covariances for derived quantities (sensitivity); and the role of covariances in the merging of the diverse nuclear data information. 226 refs., 2 tabs.« less

Text mining for neuroanatomy using WhiteText with an updated corpus and a new web application

PubMed Central

French, Leon; Liu, Po; Marais, Olivia; Koreman, Tianna; Tseng, Lucia; Lai, Artemis; Pavlidis, Paul

2015-01-01

We describe the WhiteText project, and its progress towards automatically extracting statements of neuroanatomical connectivity from text. We review progress to date on the three main steps of the project: recognition of brain region mentions, standardization of brain region mentions to neuroanatomical nomenclature, and connectivity statement extraction. We further describe a new version of our manually curated corpus that adds 2,111 connectivity statements from 1,828 additional abstracts. Cross-validation classification within the new corpus replicates results on our original corpus, recalling 67% of connectivity statements at 51% precision. The resulting merged corpus provides 5,208 connectivity statements that can be used to seed species-specific connectivity matrices and to better train automated techniques. Finally, we present a new web application that allows fast interactive browsing of the over 70,000 sentences indexed by the system, as a tool for accessing the data and assisting in further curation. Software and data are freely available at http://www.chibi.ubc.ca/WhiteText/. PMID:26052282

Preparation method and quality control of multigamma volume sources with different matrices.

PubMed

Listkowska, A; Lech, E; Saganowski, P; Tymiński, Z; Dziel, T; Cacko, D; Ziemek, T; Kołakowska, E; Broda, R

2018-04-01

The aim of the work was to develop new radioactive standard sources based on epoxy resins. The optimal proportions of the components and the homogeneity of the matrices were determined. The activity of multigamma sources prepared in Marinelli beakers was determined with reference to the National Standard of Radionuclides Activity in Poland. The difference of radionuclides activity values determined using calibrated gamma spectrometer and the activity of standard solutions used are in most cases significantly lower than measurement uncertainty limits. Sources production method and quality control procedure have been developed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Solving the Problem of Learning to Read: Children's Linguistic Awareness and Reading Progress.

ERIC Educational Resources Information Center

Abramson, Shareen

A study investigated suggested interrelationships of linguistic awareness, cognitive ability, and reading achievement. The extent to which differences in reading achievement were related to differences in the other areas was also explored. The Linguistic Awareness in Reading Test (LARR), the Coloured Progressive Matrices (CPM), and the Stanford…

Entanglement Measures in Ion-Trap Quantum Simulators without Full Tomography

DTIC Science & Technology

2014-07-21

t). This will allow us to efficiently compute correlations between ψ and ψ∗ in terms of standard expectation values in the enlarged space as follows...measure correlations of the form appearing in Eq. (2), with Θ a linear combination of tensorial products of Pauli matrices and identity operators...matrices will produce the desired correlation . Note that this protocol always results in a correlation of an odd number of Pauli matrices. In order to

Factor structure of the Hooper Visual Organization Test: a cross-cultural replication and extension.

PubMed

Merten, Thomas

2005-01-01

To investigate construct validity of the Hooper Visual Organization Test (VOT), a principal-axis analysis was performed on the neuropsychological test results of 200 German-speaking neurological patients who received a comprehensive battery, encompassing tests of visuospatial functions, memory, attention, executive functions, naming ability, and vocabulary. A four-factor solution was obtained with substantial loadings of the VOT only on the first factor, interpreted as a global dimension of non-verbal cognitive functions. This factor loaded significantly on numerous measures of visuospatial processing and attention (with particularly high loadings on WAIS-R Block Design, Trails A and B, and Raven's Standard Progressive Matrices). The remaining three factors were interpreted as memory, verbal abilities (vocabulary), and a separate factor of naming abilities.

Normative data for IQ, height and head circumference for children in Saudi Arabia.

PubMed

Batterjee, Adel A; Khaleefa, Omar; Ashaer, Khalil; Lynn, Richard

2013-07-01

Normative data are reported for intelligence, height and head circumference for a sample of 1553 6- to 15-year-olds in Saudi Arabia, and for the correlations between these variables. Intelligence was tested with the Standard Progressive Matrices, on which the Saudi sample obtained a British IQ of 76.2. There were no significant differences in means between boys and girls and differences in variability were inconsistent. The heights of the Saudi sample were generally lower than those of the American norms. The differences in head circumferences between the Saudi children and the American norms were inconsistent. Correlations between IQ and height were weaker than those found in other studies but correlations between IQ and head circumference were positive.

SAR matrices: automated extraction of information-rich SAR tables from large compound data sets.

PubMed

Wassermann, Anne Mai; Haebel, Peter; Weskamp, Nils; Bajorath, Jürgen

2012-07-23

We introduce the SAR matrix data structure that is designed to elucidate SAR patterns produced by groups of structurally related active compounds, which are extracted from large data sets. SAR matrices are systematically generated and sorted on the basis of SAR information content. Matrix generation is computationally efficient and enables processing of large compound sets. The matrix format is reminiscent of SAR tables, and SAR patterns revealed by different categories of matrices are easily interpretable. The structural organization underlying matrix formation is more flexible than standard R-group decomposition schemes. Hence, the resulting matrices capture SAR information in a comprehensive manner.

Nanocomposites from Stable Dispersions of Carbon Nanotubes in Polymeric Matrices Using Dispersion Interaction

NASA Technical Reports Server (NTRS)

Wise, Kristopher Eric (Inventor); Park, Cheol (Inventor); Kang, Jin Ho (Inventor); Siochi, Emilie J. (Inventor); Harrison, Joycelyn S. (Inventor)

2016-01-01

Stable dispersions of carbon nanotubes (CNTs) in polymeric matrices include CNTs dispersed in a host polymer or copolymer whose monomers have delocalized electron orbitals, so that a dispersion interaction results between the host polymer or copolymer and the CNTs dispersed therein. Nanocomposite products, which are presented in bulk, or when fabricated as a film, fiber, foam, coating, adhesive, paste, or molding, are prepared by standard means from the present stable dispersions of CNTs in polymeric matrices, employing dispersion interactions, as presented hereinabove.

Methods for the Determination of Chemical Substances in Marine and Estuarine Environmental Matrices - 2nd Edition

EPA Science Inventory

This NERL-Cincinnati publication, “Methods for the Determination of Chemical Substances in Marine and Estuarine Environmental Matrices - 2nd Edition” was prepared as the continuation of an initiative to gather together under a single cover a compendium of standardized laborato...

Investigating the Relationship Between Soil Water Mobility and Stable Isotope Composition with Implications for the Ecohydrologic Separation Hypothesis

NASA Astrophysics Data System (ADS)

Shuler, J.; McNamara, J. P.; Benner, S. G.; Kohn, M. J.; Evans, S.

2017-12-01

The ecohydrologic separation (ES) hypothesis states that streams and plants return different soil water compartments to the atmosphere and that these compartments bear distinct isotopic compositions that can be used to infer soil water mobility. Recent studies have found isotopic evidence for ES in a variety of ecosystems, though interpretations of these data vary. ES investigations frequently suffer from low sampling frequencies as well as incomplete or missing soil moisture and matric potential data to support assumptions of soil water mobility. We sampled bulk soil water every 2-3 weeks in the upper 1 m of a hillslope profile from May 2016 to July 2017 in a semi-arid watershed outside Boise, ID. Twig samples of three plant species were also collected concurrently. Plant and soil water samples extracted via cryogenic vacuum distillation were analyzed for δ2H and δ18O composition. Soil moisture and soil matric potential sensors were installed at five and four depths in the profile, respectively. Shallow bulk soil water was progressively enriched in both isotopes over the growing season and plotted along a soil evaporation line in a plot of δ2H versus δ18O. Plant water during the growing season plotted below both the Local Meteoric Water Line and soil evaporation line. Plant water isotopic composition could not be traced to any source sampled in this study. Additionally, soil moisture and matric potential data revealed that soils were well-drained and that mobile soil water was unavailable throughout most of the growing season at the depths sampled. Soil water isotopic composition alone failed to predict mobility as observed in soil moisture and matric potential data. These results underscore the need for standard hydrologic definitions for the mobile and immobile compartments of soil water in future studies of the ES hypothesis and ecohydrologic processes in general.

Tensiometer methods

DOEpatents

Grover, Blair K.; Hubbell, Joel M.; Sisson, James B.; Casper, William L.

2005-12-20

A method for collecting data regarding a matric potential of a media includes providing a tensiometer having a stainless steel tensiometer casing, the stainless steel tensiometer casing comprising a tip portion which includes a wetted porous stainless steel membrane through which a matric potential of a media is sensed; driving the tensiometer into the media using an insertion tube comprising a plurality of probe casing which are selectively coupled to form the insertion tube as the tensiometer is progressively driven deeper into the media, wherein the wetted porous stainless steel membrane is in contact with the media; and sensing the matric potential the media exerts on the wetted porous stainless steel membrane by a pressure sensor in fluid hydraulic connection with the porous stainless steel membrane. A tensiometer includes a stainless steel casing.

Atomic spectral-product representations of molecular electronic structure: metric matrices and atomic-product composition of molecular eigenfunctions.

PubMed

Ben-Nun, M; Mills, J D; Hinde, R J; Winstead, C L; Boatz, J A; Gallup, G A; Langhoff, P W

2009-07-02

Recent progress is reported in development of ab initio computational methods for the electronic structures of molecules employing the many-electron eigenstates of constituent atoms in spectral-product forms. The approach provides a universal atomic-product description of the electronic structure of matter as an alternative to more commonly employed valence-bond- or molecular-orbital-based representations. The Hamiltonian matrix in this representation is seen to comprise a sum over atomic energies and a pairwise sum over Coulombic interaction terms that depend only on the separations of the individual atomic pairs. Overall electron antisymmetry can be enforced by unitary transformation when appropriate, rather than as a possibly encumbering or unnecessary global constraint. The matrix representative of the antisymmetrizer in the spectral-product basis, which is equivalent to the metric matrix of the corresponding explicitly antisymmetric basis, provides the required transformation to antisymmetric or linearly independent states after Hamiltonian evaluation. Particular attention is focused in the present report on properties of the metric matrix and on the atomic-product compositions of molecular eigenstates as described in the spectral-product representations. Illustrative calculations are reported for simple but prototypically important diatomic (H(2), CH) and triatomic (H(3), CH(2)) molecules employing algorithms and computer codes devised recently for this purpose. This particular implementation of the approach combines Slater-orbital-based one- and two-electron integral evaluations, valence-bond constructions of standard tableau functions and matrices, and transformations to atomic eigenstate-product representations. The calculated metric matrices and corresponding potential energy surfaces obtained in this way elucidate a number of aspects of the spectral-product development, including the nature of closure in the representation, the general redundancy or linear dependence of its explicitly antisymmetrized form, the convergence of the apparently disparate atomic-product and explicitly antisymmetrized atomic-product forms to a common invariant subspace, and the nature of a chemical bonding descriptor provided by the atomic-product compositions of molecular eigenstates. Concluding remarks indicate additional studies in progress and the prognosis for performing atomic spectral-product calculations more generally and efficiently.

An improved approach to the analysis of drug-protein binding by distance geometry

NASA Technical Reports Server (NTRS)

Goldblum, A.; Kieber-Emmons, T.; Rein, R.

1986-01-01

The calculation of side chain centers of coordinates and the subsequent generation of side chain-side chain and side chain-backbone distance matrices is suggested as an improved method for viewing interactions inside proteins and for the comparison of protein structures. The use of side chain distance matrices is demonstrated with free PTI, and the use of difference distance matrices for side chains is shown for free and trypsin-bound PTI as well as for the X-ray structures of trypsin complexes with PTI and with benzamidine. It is found that conformational variations are reflected in the side chain distance matrices much more than in the standard C-C distance representations.

On the representation matrices of the spin permutation group. [for atomic and molecular electronic structures

NASA Technical Reports Server (NTRS)

Wilson, S.

1977-01-01

A method is presented for the determination of the representation matrices of the spin permutation group (symmetric group), a detailed knowledge of these matrices being required in the study of the electronic structure of atoms and molecules. The method is characterized by the use of two different coupling schemes. Unlike the Yamanouchi spin algebraic scheme, the method is not recursive. The matrices for the fundamental transpositions can be written down directly in one of the two bases. The method results in a computationally significant reduction in the number of matrix elements that have to be stored when compared with, say, the standard Young tableaux group theoretical approach.

Two-dimensional integrating matrices on rectangular grids. [solving differential equations associated with rotating structures

NASA Technical Reports Server (NTRS)

Lakin, W. D.

1981-01-01

The use of integrating matrices in solving differential equations associated with rotating beam configurations is examined. In vibration problems, by expressing the equations of motion of the beam in matrix notation, utilizing the integrating matrix as an operator, and applying the boundary conditions, the spatial dependence is removed from the governing partial differential equations and the resulting ordinary differential equations can be cast into standard eigenvalue form. Integrating matrices are derived based on two dimensional rectangular grids with arbitrary grid spacings allowed in one direction. The derivation of higher dimensional integrating matrices is the initial step in the generalization of the integrating matrix methodology to vibration and stability problems involving plates and shells.

Deterministic matrices matching the compressed sensing phase transitions of Gaussian random matrices

PubMed Central

Monajemi, Hatef; Jafarpour, Sina; Gavish, Matan; Donoho, David L.; Ambikasaran, Sivaram; Bacallado, Sergio; Bharadia, Dinesh; Chen, Yuxin; Choi, Young; Chowdhury, Mainak; Chowdhury, Soham; Damle, Anil; Fithian, Will; Goetz, Georges; Grosenick, Logan; Gross, Sam; Hills, Gage; Hornstein, Michael; Lakkam, Milinda; Lee, Jason; Li, Jian; Liu, Linxi; Sing-Long, Carlos; Marx, Mike; Mittal, Akshay; Monajemi, Hatef; No, Albert; Omrani, Reza; Pekelis, Leonid; Qin, Junjie; Raines, Kevin; Ryu, Ernest; Saxe, Andrew; Shi, Dai; Siilats, Keith; Strauss, David; Tang, Gary; Wang, Chaojun; Zhou, Zoey; Zhu, Zhen

2013-01-01

In compressed sensing, one takes samples of an N-dimensional vector using an matrix A, obtaining undersampled measurements . For random matrices with independent standard Gaussian entries, it is known that, when is k-sparse, there is a precisely determined phase transition: for a certain region in the (,)-phase diagram, convex optimization typically finds the sparsest solution, whereas outside that region, it typically fails. It has been shown empirically that the same property—with the same phase transition location—holds for a wide range of non-Gaussian random matrix ensembles. We report extensive experiments showing that the Gaussian phase transition also describes numerous deterministic matrices, including Spikes and Sines, Spikes and Noiselets, Paley Frames, Delsarte-Goethals Frames, Chirp Sensing Matrices, and Grassmannian Frames. Namely, for each of these deterministic matrices in turn, for a typical k-sparse object, we observe that convex optimization is successful over a region of the phase diagram that coincides with the region known for Gaussian random matrices. Our experiments considered coefficients constrained to for four different sets , and the results establish our finding for each of the four associated phase transitions. PMID:23277588

The tangled bank of amino acids

PubMed Central

Pollock, David D.

2016-01-01

Abstract The use of amino acid substitution matrices to model protein evolution has yielded important insights into both the evolutionary process and the properties of specific protein families. In order to make these models tractable, standard substitution matrices represent the average results of the evolutionary process rather than the underlying molecular biophysics and population genetics, treating proteins as a set of independently evolving sites rather than as an integrated biomolecular entity. With advances in computing and the increasing availability of sequence data, we now have an opportunity to move beyond current substitution matrices to more interpretable mechanistic models with greater fidelity to the evolutionary process of mutation and selection and the holistic nature of the selective constraints. As part of this endeavour, we consider how epistatic interactions induce spatial and temporal rate heterogeneity, and demonstrate how these generally ignored factors can reconcile standard substitution rate matrices and the underlying biology, allowing us to better understand the meaning of these substitution rates. Using computational simulations of protein evolution, we can demonstrate the importance of both spatial and temporal heterogeneity in modelling protein evolution. PMID:27028523

What's the Bottom Line

EPA Science Inventory

Advances in analytical instrumentation have not only increased the number and types of chemicals measured, but reduced the quantitation limits, allowing these chemicals to be detected at progressively lower concentrations in various environmental matrices. Such analytical advanc...

Is IQ in childhood associated with suicidal thoughts and attempts? Findings from the Mater University Study of Pregnancy and its outcomes.

PubMed

Alati, Rosa; Gunnell, David; Najman, Jake; Williams, Gail; Lawlor, Debbie

2009-06-01

This study explores associations of IQ at age 14 with adult symptoms of suicidal thoughts and attempts at age 21. Analysis was based on the Mater University Study of Pregnancy and its outcomes, an Australian prospective birth cohort study started in Brisbane Australia in 1981. We assessed associations with suicide thoughts, plans, and attempts. We used two measures of IQ: the Raven's Standard Progressive Matrices and the Wide Range Achievement Test. In multivariable analyses, there was an inverse association between Raven's IQ and suicide thoughts, plans, and attempts, but no strong evidence of an association between the WRAT3 and the three suicidal items. Specific aspects of intelligence may be associated with suicidal thoughts, plans, and attempts.

DCTune Perceptual Optimization of Compressed Dental X-Rays

NASA Technical Reports Server (NTRS)

Watson, Andrew B.; Null, Cynthia H. (Technical Monitor)

1996-01-01

In current dental practice, x-rays of completed dental work are often sent to the insurer for verification. It is faster and cheaper to transmit instead digital scans of the x-rays. Further economies result if the images are sent in compressed form. DCTune is a technology for optimizing DCT (digital communication technology) quantization matrices to yield maximum perceptual quality for a given bit-rate, or minimum bit-rate for a given perceptual quality. Perceptual optimization of DCT color quantization matrices. In addition, the technology provides a means of setting the perceptual quality of compressed imagery in a systematic way. The purpose of this research was, with respect to dental x-rays, 1) to verify the advantage of DCTune over standard JPEG (Joint Photographic Experts Group), 2) to verify the quality control feature of DCTune, and 3) to discover regularities in the optimized matrices of a set of images. We optimized matrices for a total of 20 images at two resolutions (150 and 300 dpi) and four bit-rates (0.25, 0.5, 0.75, 1.0 bits/pixel), and examined structural regularities in the resulting matrices. We also conducted psychophysical studies (1) to discover the DCTune quality level at which the images became 'visually lossless,' and (2) to rate the relative quality of DCTune and standard JPEG images at various bitrates. Results include: (1) At both resolutions, DCTune quality is a linear function of bit-rate. (2) DCTune quantization matrices for all images at all bitrates and resolutions are modeled well by an inverse Gaussian, with parameters of amplitude and width. (3) As bit-rate is varied, optimal values of both amplitude and width covary in an approximately linear fashion. (4) Both amplitude and width vary in systematic and orderly fashion with either bit-rate or DCTune quality; simple mathematical functions serve to describe these relationships. (5) In going from 150 to 300 dpi, amplitude parameters are substantially lower and widths larger at corresponding bit-rates or qualities. (6) Visually lossless compression occurs at a DCTune quality value of about 1. (7) At 0.25 bits/pixel, comparative ratings give DCTune a substantial advantage over standard JPEG. As visually lossless bit-rates are approached, this advantage of necessity diminishes. We have concluded that DCTune optimized quantization matrices provide better visual quality than standard JPEG. Meaningful quality levels may be specified by means of the DCTune metric. Optimized matrices are very similar across the class of dental x-rays, suggesting the possibility of a 'class-optimal' matrix. DCTune technology appears to provide some value in the context of compressed dental x-rays.

Functional Alterations in Neural Substrates of Geometric Reasoning in Adults with High-Functioning Autism

PubMed Central

Yamada, Takashi; Ohta, Haruhisa; Watanabe, Hiromi; Kanai, Chieko; Tani, Masayuki; Ohno, Taisei; Takayama, Yuko; Iwanami, Akira; Kato, Nobumasa; Hashimoto, Ryuichiro

2012-01-01

Individuals with autism spectrum condition (ASC) are known to excel in some perceptual cognitive tasks, but such developed functions have been often regarded as “islets of abilities” that do not significantly contribute to broader intellectual capacities. However, recent behavioral studies have reported that individuals with ASC have advantages for performing Raven's (Standard) Progressive Matrices (RPM/RSPM), a standard neuropsychological test for general fluid intelligence, raising the possibility that ASC′s cognitive strength can be utilized for more general purposes like novel problem solving. Here, the brain activity of 25 adults with high-functioning ASC and 26 matched normal controls (NC) was measured using functional magnetic resonance imaging (fMRI) to examine neural substrates of geometric reasoning during the engagement of a modified version of the RSPM test. Among the frontal and parietal brain regions involved in fluid intelligence, ASC showed larger activation in the left lateral occipitotemporal cortex (LOTC) during an analytic condition with moderate difficulty than NC. Activation in the left LOTC and ventrolateral prefrontal cortex (VLPFC) increased with task difficulty in NC, whereas such modulation of activity was absent in ASC. Furthermore, functional connectivity analysis revealed a significant reduction of activation coupling between the left inferior parietal cortex and the right anterior prefrontal cortex during both figural and analytic conditions in ASC. These results indicate altered pattern of functional specialization and integration in the neural system for geometric reasoning in ASC, which may explain its atypical cognitive pattern, including performance on the Raven's Matrices test. PMID:22912831

Incontinence in children with treated attention-deficit/hyperactivity disorder.

PubMed

Niemczyk, J; Equit, M; Hoffmann, L; von Gontard, A

2015-06-01

Attention-deficit/hyperactivity disorder (ADHD) and incontinence (nocturnal enuresis, daytime urinary incontinence and fecal incontinence) are common disorders in childhood. Both disorders are strongly associated with each other. ADHD can affect compliance to incontinence therapy in a negative way; it can also affect outcome. The aim of the present study was to assess the prevalence of incontinence, age of bladder and bowel control, and psychological symptoms in children having treatment for ADHD compared to a control group. Forty children having treatment for ADHD (75% boys, mean age 11.4 years) and 43 matched controls (60.5% boys, mean age 10.7 years) were assessed. Their parents filled out questionnaires to assess: child psychopathology (Child Behavior Checklist), incontinence (Parental Questionnaire: Enuresis/Urinary Incontinence; Encopresis Questionnaire - Screening Version) and symptoms of the lower urinary tract (International-Consultation-on-Incontinence-Questionnaire - Pediatric Lower Urinary Tract Symptoms). The ICD-10 diagnoses and children's IQ were measured by standardized instruments (Kinder-DIPS, Coloured Progressive Matrices/Standard Progressive Matrices). Rates of incontinence in the ADHD group (5% nocturnal enuresis, 5% daytime urinary incontinence, 2.5% fecal incontinence) did not differ significantly from incontinence rates in the control group (4.7% daytime urinary incontinence). More children in the ADHD group had Child Behavior Checklist scores in the clinical range. Further ICD-10 disorders were present in eight children with ADHD and in one control child. More children with ADHD had delayed daytime and nighttime bladder control, as well as delayed bowel control, than the controls. The present study showed that if children are treated for their ADHD, according to standard practice guidelines, incontinence rates are similar to those without ADHD. More children with ADHD reached continence at a later age than the controls, which could be an indicator of maturational deficits in the central nervous system. Additionally, children with ADHD showed higher rates of clinically relevant psychological symptoms. This study provides further information of the association between ADHD and incontinence. Treatment of ADHD may be associated with positive effects on incontinence outcomes. Therefore, children with ADHD should always be screened for incontinence problems and children with incontinence problems should also be screened for ADHD if symptoms of hyperactivity, inattention and/or impulsivity are also present. Copyright © 2015 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.

Tensiometer methods and apparatus

DOEpatents

Grover, Blair K.; Hubbell, Joel M.; Sisson, James B.; Casper, William L.

2004-08-10

A method for collecting data regarding a matric potential of a media includes providing a tensiometer having a stainless steel tensiometer casing, the stainless steel tensiometer casing comprising a tip portion which includes a wetted porous stainless steel membrane through which a matric potential of a media is sensed; driving the tensiometer into the media using an insertion tube comprising a plurality of probe casing which are selectively coupled to form the insertion tube as the tensiometer is progressively driven deeper into the media, wherein the wetted porous stainless steel membrane is in contact with the media; and sensing the matric potential the media exerts on the wetted porous stainless steel membrane by a pressure sensor in fluid hydraulic connection with the porous stainless steel membrane. A tensiometer includes a stainless steel casing.

Compound matrices

NASA Astrophysics Data System (ADS)

Kravvaritis, Christos; Mitrouli, Marilena

2009-02-01

This paper studies the possibility to calculate efficiently compounds of real matrices which have a special form or structure. The usefulness of such an effort lies in the fact that the computation of compound matrices, which is generally noneffective due to its high complexity, is encountered in several applications. A new approach for computing the Singular Value Decompositions (SVD's) of the compounds of a matrix is proposed by establishing the equality (up to a permutation) between the compounds of the SVD of a matrix and the SVD's of the compounds of the matrix. The superiority of the new idea over the standard method is demonstrated. Similar approaches with some limitations can be adopted for other matrix factorizations, too. Furthermore, formulas for the n - 1 compounds of Hadamard matrices are derived, which dodge the strenuous computations of the respective numerous large determinants. Finally, a combinatorial counting technique for finding the compounds of diagonal matrices is illustrated.

Psychological Dissection of Patients Having Dissociative Disorder: A Cross-sectional Study

PubMed Central

Reddy, Lohit Somashekar; Patil, N. M.; Nayak, Raghavendra B.; Chate, Sameeran S.; Ansari, Saba

2018-01-01

Background: Patients present with dissociative disorders as a decompensation to underlying stressful situation. It is clinically important to evaluate the presence, type, and temporal relation of the stressors resulting in dissociation. Further knowing the sociodemographic and psychological profile of the dissociative patient helps in better management. Materials and Methods: The study included 55 dissociative patients aged between 5 to 45 years. Psychiatric diagnosis was made using ICD-10 DCR. Psychosocial stressors and stressful life events were assessed using presumptive stressful life events scale/life events scale for Indian children and clinical interview. Personality and temperament traits were assessed using medico psychological questionnaire and temperament measurement schedule, respectively. Intelligence quotient (IQ) was assessed using standard progressive matrices and colored progressive matrices. Statistical analysis was done using Epi Info 7 software. Results: All patients had significant psychosocial stressors preceding dissociation. Precipitating factor with temporal association was observed in only 83.64%. Family disharmony (41.82%) followed by education-related problems (29.09%) was the most common psychosocial stressors. 61.82% of the dissociative patients had psychiatric comorbidity. Mean IQ of study sample was 92.47. Dissociative children had high emotionality and energy levels but low sociability, rhythmicity, and distractibility. 50% of the adults were neurotic and had emotionally unstable personality. Conclusion: Dissociative disorders are commonly seen in females, adolescents, and in those from lower socioeconomic status and rural areas. They are always preceded by psychosocial stressors. Most of them have comorbid psychiatric disorders such as depression and anxiety. Neuroticism and emotionally unstable personality traits are common in adult patients while temperamental traits such as low sociability, low rhythmicity, low distractibility, high emotionality, and high energy levels are common in children. PMID:29403129

Psychological Dissection of Patients Having Dissociative Disorder: A Cross-sectional Study.

PubMed

Reddy, Lohit Somashekar; Patil, N M; Nayak, Raghavendra B; Chate, Sameeran S; Ansari, Saba

2018-01-01

Patients present with dissociative disorders as a decompensation to underlying stressful situation. It is clinically important to evaluate the presence, type, and temporal relation of the stressors resulting in dissociation. Further knowing the sociodemographic and psychological profile of the dissociative patient helps in better management. The study included 55 dissociative patients aged between 5 to 45 years. Psychiatric diagnosis was made using ICD-10 DCR. Psychosocial stressors and stressful life events were assessed using presumptive stressful life events scale/life events scale for Indian children and clinical interview. Personality and temperament traits were assessed using medico psychological questionnaire and temperament measurement schedule, respectively. Intelligence quotient (IQ) was assessed using standard progressive matrices and colored progressive matrices. Statistical analysis was done using Epi Info 7 software. All patients had significant psychosocial stressors preceding dissociation. Precipitating factor with temporal association was observed in only 83.64%. Family disharmony (41.82%) followed by education-related problems (29.09%) was the most common psychosocial stressors. 61.82% of the dissociative patients had psychiatric comorbidity. Mean IQ of study sample was 92.47. Dissociative children had high emotionality and energy levels but low sociability, rhythmicity, and distractibility. 50% of the adults were neurotic and had emotionally unstable personality. Dissociative disorders are commonly seen in females, adolescents, and in those from lower socioeconomic status and rural areas. They are always preceded by psychosocial stressors. Most of them have comorbid psychiatric disorders such as depression and anxiety. Neuroticism and emotionally unstable personality traits are common in adult patients while temperamental traits such as low sociability, low rhythmicity, low distractibility, high emotionality, and high energy levels are common in children.

Determination of gamma-aminobutyric acid in food matrices by isotope dilution hydrophilic interaction chromatography coupled to mass spectrometry.

PubMed

Zazzeroni, Raniero; Homan, Andrew; Thain, Emma

2009-08-01

The estimation of the dietary intake of gamma-aminobutyric acid (GABA) is dependent upon the knowledge of its concentration values in food matrices. To this end, an isotope dilution liquid chromatography-mass spectrometry method has been developed employing the hydrophilic interaction chromatography technique for analyte separation. This approach enabled accurate quantification of GABA in apple, potato, soybeans, and orange juice without the need of a pre- or post-column derivatization reaction. A selective and precise analytical measurement has been obtained with a triple quadrupole mass spectrometer operating in multiple reaction monitoring using the method of standard additions and GABA-d(6) as an internal standard. The concentrations of GABA found in the matrices tested are 7 microg/g of apple, 342 microg/g of potatoes, 211 microg/g of soybeans, and 344 microg/mL of orange juice.

A progress report on estuary modeling by the finite-element method

USGS Publications Warehouse

Gray, William G.

1978-01-01

Various schemes are investigated for finite-element modeling of two-dimensional surface-water flows. The first schemes investigated combine finite-element spatial discretization with split-step time stepping schemes that have been found useful in finite-difference computations. Because of the large number of numerical integrations performed in space and the large sparse matrices solved, these finite-element schemes were found to be economically uncompetitive with finite-difference schemes. A very promising leapfrog scheme is proposed which, when combined with a novel very fast spatial integration procedure, eliminates the need to solve any matrices at all. Additional problems attacked included proper propagation of waves and proper specification of the normal flow-boundary condition. This report indicates work in progress and does not come to a definitive conclusion as to the best approach for finite-element modeling of surface-water problems. The results presented represent findings obtained between September 1973 and July 1976. (Woodard-USGS)

Improvement of Visuo-spatial Function Assessed by Raven’s Colored Progressive Matrices in Dementia with Lewy Bodies by Donepezil Treatment

PubMed Central

Yoshino, Yuta; Mori, Takaaki; Yoshida, Taku; Toyota, Yasutaka; Shimizu, Hideaki; Iga, Jun-ichi; Nishitani, Shusaku; Ueno, Shu-ichi

2017-01-01

Objective Donepezil is used to improve cognitive impairment of dementia with Lewy bodies (DLB). Visuo-spatial dysfunction is a well-known symptom of DLB. Non-verbal Raven’s Colored Progressive Matrices (RCPM) were used to assess both visual perception and reasoning ability in DLB subjects treated with donepezil. Methods Twenty-one DLB patients (mean age, 78.7±4.5 years) were enrolled. RCPM assessment was performed at the time of starting donepezil and within one year after starting donepezil. Results There were significant improvements of RCPM in the total scores between one year donepezil treatment (p=0.013), in both Set A score (p=0.002) and Set AB score (p=0.015), but trend in the Set B score (p=0.083). Conclusion Donepezil is useful for improving visuo-spatial impairment in DLB, but not for problem-solving impairment. PMID:28783933

Elemental Analysis in Biological Matrices Using ICP-MS.

PubMed

Hansen, Matthew N; Clogston, Jeffrey D

2018-01-01

The increasing exploration of metallic nanoparticles for use as cancer therapeutic agents necessitates a sensitive technique to track the clearance and distribution of the material once introduced into a living system. Inductively coupled plasma mass spectrometry (ICP-MS) provides a sensitive and selective tool for tracking the distribution of metal components from these nanotherapeutics. This chapter presents a standardized method for processing biological matrices, ensuring complete homogenization of tissues, and outlines the preparation of appropriate standards and controls. The method described herein utilized gold nanoparticle-treated samples; however, the method can easily be applied to the analysis of other metals.

Comparison of characteristic flavor and aroma volatiles in melons and standards using solid phase microextraction (SPME) and Stir Bar Sorptive Extraction (SBSE) with GC-MS.

USDA-ARS?s Scientific Manuscript database

Stir bar sorptive extraction (SBSE) is a technique for extraction and analysis of organic compounds in aqueous matrices, similar in theory to solid phase microextraction (SPME). SBSE has been successfully used to analyze several organic compounds, including food matrices. When compared with SPME, ...

Strategy for simultaneous molecular detection of the protozoan parasites Toxoplasma, Cryptosporidium and Giardia in food matrices and persistence on leaves of vegetables during storage at 4°C

USDA-ARS?s Scientific Manuscript database

Toxoplasma gondii, Cryptosporidium spp. and Giardia intestinalis are emerging pathogen parasites in the food domain. However, without standardized method for their detection in food matrices, parasitic foodborne outbreaks remain neglected. In this study, a new immunomagnetic separation assay (IMS To...

The tangled bank of amino acids.

PubMed

Goldstein, Richard A; Pollock, David D

2016-07-01

The use of amino acid substitution matrices to model protein evolution has yielded important insights into both the evolutionary process and the properties of specific protein families. In order to make these models tractable, standard substitution matrices represent the average results of the evolutionary process rather than the underlying molecular biophysics and population genetics, treating proteins as a set of independently evolving sites rather than as an integrated biomolecular entity. With advances in computing and the increasing availability of sequence data, we now have an opportunity to move beyond current substitution matrices to more interpretable mechanistic models with greater fidelity to the evolutionary process of mutation and selection and the holistic nature of the selective constraints. As part of this endeavour, we consider how epistatic interactions induce spatial and temporal rate heterogeneity, and demonstrate how these generally ignored factors can reconcile standard substitution rate matrices and the underlying biology, allowing us to better understand the meaning of these substitution rates. Using computational simulations of protein evolution, we can demonstrate the importance of both spatial and temporal heterogeneity in modelling protein evolution. © 2016 The Authors Protein Science published by Wiley Periodicals, Inc. on behalf of The Protein Society.

Intermittency and random matrices

NASA Astrophysics Data System (ADS)

Sokoloff, Dmitry; Illarionov, E. A.

2015-08-01

A spectacular phenomenon of intermittency, i.e. a progressive growth of higher statistical moments of a physical field excited by an instability in a random medium, attracted the attention of Zeldovich in the last years of his life. At that time, the mathematical aspects underlying the physical description of this phenomenon were still under development and relations between various findings in the field remained obscure. Contemporary results from the theory of the product of independent random matrices (the Furstenberg theory) allowed the elaboration of the phenomenon of intermittency in a systematic way. We consider applications of the Furstenberg theory to some problems in cosmology and dynamo theory.

Monitoring the progression of calcium and protein solubilisation as affected by calcium chelators during small-scale manufacture of casein-based food matrices.

PubMed

McIntyre, Irene; O'Sullivan, Michael; O'Riordan, Dolores

2017-12-15

Calcium and protein solubilisation during small-scale manufacture of semi-solid casein-based food matrices was investigated and found to be very different in the presence or absence of calcium chelating salts. Calcium concentrations in the dispersed phase increased and calcium-ion activity (A Ca ++ ) decreased during manufacture of the matrices containing calcium chelating salts; with ∼23% of total calcium solubilised by the end of manufacture. In the absence of calcium chelating salts, these concentrations were significantly lower at equivalent processing times and remained unchanged as did A Ca ++ , throughout manufacture. The protein content of the dispersed phase was low (≤3% of total protein), but was significantly higher for matrices containing calcium chelating salts. This study elucidates the critical role of calcium chelating salts in modulating casein hydration and dispersion and gives an indication of the levels of soluble calcium and protein required to allow matrix formation during manufacture of casein-based food structures e.g. processed and analogue cheese. Copyright © 2017 Elsevier Ltd. All rights reserved.

Hierarchical matrices implemented into the boundary integral approaches for gravity field modelling

NASA Astrophysics Data System (ADS)

Čunderlík, Róbert; Vipiana, Francesca

2017-04-01

Boundary integral approaches applied for gravity field modelling have been recently developed to solve the geodetic boundary value problems numerically, or to process satellite observations, e.g. from the GOCE satellite mission. In order to obtain numerical solutions of "cm-level" accuracy, such approaches require very refined level of the disretization or resolution. This leads to enormous memory requirements that need to be reduced. An implementation of the Hierarchical Matrices (H-matrices) can significantly reduce a numerical complexity of these approaches. A main idea of the H-matrices is based on an approximation of the entire system matrix that is split into a family of submatrices. Large submatrices are stored in factorized representation, while small submatrices are stored in standard representation. This allows reducing memory requirements significantly while improving the efficiency. The poster presents our preliminary results of implementations of the H-matrices into the existing boundary integral approaches based on the boundary element method or the method of fundamental solution.

The Infinitesimal Jackknife with Exploratory Factor Analysis

ERIC Educational Resources Information Center

Zhang, Guangjian; Preacher, Kristopher J.; Jennrich, Robert I.

2012-01-01

The infinitesimal jackknife, a nonparametric method for estimating standard errors, has been used to obtain standard error estimates in covariance structure analysis. In this article, we adapt it for obtaining standard errors for rotated factor loadings and factor correlations in exploratory factor analysis with sample correlation matrices. Both…

How to gain eleven IQ points in ten minutes: thinking aloud improves Raven's Matrices performance in older adults.

PubMed

Fox, Mark C; Charness, Neil

2010-03-01

Few studies have examined the impact of age on reactivity to concurrent think-aloud (TA) verbal reports. An initial study with 30 younger and 31 older adults revealed that thinking aloud improves older adult performance on a short form of the Raven's Matrices (Bors & Stokes, 1998, Educational and Psychological Measurement, 58, p. 382) but did not affect other tasks. In the replication experiment, 30 older adults (mean age = 73.0) performed the Raven's Matrices and three other tasks to replicate and extend the findings of the initial study. Once again older adults performed significantly better only on the Raven's Matrices while thinking aloud. Performance gains on this task were substantial (d = 0.73 and 0.92 in Experiments 1 and 2, respectively), corresponding to a fluid intelligence increase of nearly one standard deviation.

Biochemical thermodynamics: applications of Mathematica.

PubMed

Alberty, Robert A

2006-01-01

The most efficient way to store thermodynamic data on enzyme-catalyzed reactions is to use matrices of species properties. Since equilibrium in enzyme-catalyzed reactions is reached at specified pH values, the thermodynamics of the reactions is discussed in terms of transformed thermodynamic properties. These transformed thermodynamic properties are complicated functions of temperature, pH, and ionic strength that can be calculated from the matrices of species values. The most important of these transformed thermodynamic properties is the standard transformed Gibbs energy of formation of a reactant (sum of species). It is the most important because when this function of temperature, pH, and ionic strength is known, all the other standard transformed properties can be calculated by taking partial derivatives. The species database in this package contains data matrices for 199 reactants. For 94 of these reactants, standard enthalpies of formation of species are known, and so standard transformed Gibbs energies, standard transformed enthalpies, standard transformed entropies, and average numbers of hydrogen atoms can be calculated as functions of temperature, pH, and ionic strength. For reactions between these 94 reactants, the changes in these properties can be calculated over a range of temperatures, pHs, and ionic strengths, and so can apparent equilibrium constants. For the other 105 reactants, only standard transformed Gibbs energies of formation and average numbers of hydrogen atoms at 298.15 K can be calculated. The loading of this package provides functions of pH and ionic strength at 298.15 K for standard transformed Gibbs energies of formation and average numbers of hydrogen atoms for 199 reactants. It also provides functions of temperature, pH, and ionic strength for the standard transformed Gibbs energies of formation, standard transformed enthalpies of formation, standard transformed entropies of formation, and average numbers of hydrogen atoms for 94 reactants. Thus loading this package makes available 774 mathematical functions for these properties. These functions can be added and subtracted to obtain changes in these properties in biochemical reactions and apparent equilibrium constants.

Comparison of Procedures for Detecting Test-Item Bias with Both Internal and External Ability Criteria.

ERIC Educational Resources Information Center

Shepard, Lorrie, And Others

1981-01-01

Sixteen approaches for detecting item bias were compared on samples of Black, White, and Chicano elementary school pupils using the Lorge-Thorndike and Raven's Coloured Progressive Matrices tests. Recommendations for practical use are made. (JKS)

THE REGULAR FOURIER MATRICES AND NONUNIFORM FAST-FOURIER TRANSFORMS. (R825225)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

DIMETHYLITHIOARSINIC ANHYDRIDE: A STANDARD FOR ARSENIC SPECIATION

EPA Science Inventory

Recently, sulfar analogs of well know arsenicals have been identfied in biolgical, dietary and environmental matrices. These discoveries have generated a need for stable species-specific standards. This presentation will forcus on the isolation and characterization of a standar...

Absorption and resonance Raman spectra of Pb2, Pb3, and Pb4 in xenon matrices

NASA Technical Reports Server (NTRS)

Stranz, D. D.; Khanna, R. K.

1981-01-01

Matrix isolation techniques are used to investigate the spectra of lead molecules and, in particular, to obtain resonance Raman spectra of lead vapors isolated in solid xenon matrices. The presence of Pb2 is confirmed by the visible adsorption, and Raman spectra yield a vibrational frequency for the ground state of 108 per cm and a dissociation energy of 8200 per cm. A second resonance Raman progression indicates a Pb3 species of D3h symmetry. Finally, two additional Raman features at approximately 111 per cm spacing are evidence for a third species, tentatively identified as Pb4.

Psychometric Investigation of the Raven's Colored Progressive Matrices Test in a Sample of Preschool Children.

PubMed

Lúcio, Patrícia Silva; Cogo-Moreira, Hugo; Puglisi, Marina; Polanczyk, Guilherme Vanoni; Little, Todd D

2017-11-01

The present study investigated the psychometric properties of the Raven's Colored Progressive Matrices (CPM) test in a sample of preschoolers from Brazil ( n = 582; age: mean = 57 months, SD = 7 months; 46% female). We investigated the plausibility of unidimensionality of the items (confirmatory factor analysis) and differential item functioning (DIF) for sex and age (multiple indicators multiple causes method). We tested four unidimensional models and the one with the best-fit index was a reduced form of the Raven's CPM. The DIF analysis was carried out with the reduced form of the test. A few items presented DIF (two for sex and one for age), confirming that the Raven's CPM items are mostly measurement invariant. There was no effect of sex on the general factor, but increasing age was associated with higher values of the g factor. Future research should indicate if the reduced form is suitable for evaluating the general ability of preschoolers.

Asymmetric correlation matrices: an analysis of financial data

NASA Astrophysics Data System (ADS)

Livan, G.; Rebecchi, L.

2012-06-01

We analyse the spectral properties of correlation matrices between distinct statistical systems. Such matrices are intrinsically non-symmetric, and lend themselves to extend the spectral analyses usually performed on standard Pearson correlation matrices to the realm of complex eigenvalues. We employ some recent random matrix theory results on the average eigenvalue density of this type of matrix to distinguish between noise and non-trivial correlation structures, and we focus on financial data as a case study. Namely, we employ daily prices of stocks belonging to the American and British stock exchanges, and look for the emergence of correlations between two such markets in the eigenvalue spectrum of their non-symmetric correlation matrix. We find several non trivial results when considering time-lagged correlations over short lags, and we corroborate our findings by additionally studying the asymmetric correlation matrix of the principal components of our datasets.

Detection of Botulinum Neurotoxin Serotype A, B, and F Proteolytic Activity in Complex Matrices with Picomolar to Femtomolar Sensitivity

PubMed Central

Dunning, F. Mark; Ruge, Daniel R.; Piazza, Timothy M.; Stanker, Larry H.; Zeytin, Füsûn N.

2012-01-01

Rapid, high-throughput assays that detect and quantify botulinum neurotoxin (BoNT) activity in diverse matrices are required for environmental, clinical, pharmaceutical, and food testing. The current standard, the mouse bioassay, is sensitive but is low in throughput and precision. In this study, we present three biochemical assays for the detection and quantification of BoNT serotype A, B, and F proteolytic activities in complex matrices that offer picomolar to femtomolar sensitivity with small assay volumes and total assay times of less than 24 h. These assays consist of magnetic beads conjugated with BoNT serotype-specific antibodies that are used to purify BoNT from complex matrices before the quantification of bound BoNT proteolytic activity using the previously described BoTest reporter substrates. The matrices tested include human serum, whole milk, carrot juice, and baby food, as well as buffers containing common pharmaceutical excipients. The limits of detection were below 1 pM for BoNT/A and BoNT/F and below 10 pM for BoNT/B in most tested matrices using 200-μl samples and as low as 10 fM for BoNT/A with an increased sample volume. Together, these data describe rapid, robust, and high-throughput assays for BoNT detection that are compatible with a wide range of matrices. PMID:22923410

An implementation of the look-ahead Lanczos algorithm for non-Hermitian matrices

NASA Technical Reports Server (NTRS)

Freund, Roland W.; Gutknecht, Martin H.; Nachtigal, Noel M.

1991-01-01

The nonsymmetric Lanczos method can be used to compute eigenvalues of large sparse non-Hermitian matrices or to solve large sparse non-Hermitian linear systems. However, the original Lanczos algorithm is susceptible to possible breakdowns and potential instabilities. An implementation is presented of a look-ahead version of the Lanczos algorithm that, except for the very special situation of an incurable breakdown, overcomes these problems by skipping over those steps in which a breakdown or near-breakdown would occur in the standard process. The proposed algorithm can handle look-ahead steps of any length and requires the same number of matrix-vector products and inner products as the standard Lanczos process without look-ahead.

Association of chronotype and social jetlag with human non-verbal intelligence.

PubMed

Panev, A S; Tserne, T A; Polugrudov, A S; Bakutova, L A; Petrova, N B; Tatarinova, O V; Kolosova, O N; Borisenkov, M F

2017-01-01

The aim of this study was to evaluate the effects of chronotype and social jetlag (SJL) on intelligence. Subjects were aged 14-25 years (n = 1008). A significant effect of intelligence on academic performance, as measured by the Raven's Standard Progressive Matrices test, was found (F 2,917 = 11.75, P < 0.0001, η 2 = 0.03). When SJL was less than 2 hours, the intelligence of people with late chronotype was found to be higher than that of subjects with early and intermediate chronotypes (F 2,305 = 3.12, P < 0.05, η 2 = 0.02). A negative effect of SJL on the results of intelligence testing was noted only in subjects with late chronotype (F 2,536 = 2.61, P < 0.05, η 2 = 0.02). Our data suggest that people with late chronotype have a higher level of intelligence, but these advantages disappear when SJL ≥2 hours.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghysels, Pieter; Li, Xiaoye S.; Rouet, Francois -Henry

Here, we present a sparse linear system solver that is based on a multifrontal variant of Gaussian elimination and exploits low-rank approximation of the resulting dense frontal matrices. We use hierarchically semiseparable (HSS) matrices, which have low-rank off-diagonal blocks, to approximate the frontal matrices. For HSS matrix construction, a randomized sampling algorithm is used together with interpolative decompositions. The combination of the randomized compression with a fast ULV HSS factoriz ation leads to a solver with lower computational complexity than the standard multifrontal method for many applications, resulting in speedups up to 7 fold for problems in our test suite.more » The implementation targets many-core systems by using task parallelism with dynamic runtime scheduling. Numerical experiments show performance improvements over state-of-the-art sparse direct solvers. The implementation achieves high performance and good scalability on a range of modern shared memory parallel systems, including the Intel Xeon Phi (MIC). The code is part of a software package called STRUMPACK - STRUctured Matrices PACKage, which also has a distributed memory component for dense rank-structured matrices.« less

An Efficient Multicore Implementation of a Novel HSS-Structured Multifrontal Solver Using Randomized Sampling

DOE PAGES

Ghysels, Pieter; Li, Xiaoye S.; Rouet, Francois -Henry; ...

2016-10-27

Here, we present a sparse linear system solver that is based on a multifrontal variant of Gaussian elimination and exploits low-rank approximation of the resulting dense frontal matrices. We use hierarchically semiseparable (HSS) matrices, which have low-rank off-diagonal blocks, to approximate the frontal matrices. For HSS matrix construction, a randomized sampling algorithm is used together with interpolative decompositions. The combination of the randomized compression with a fast ULV HSS factoriz ation leads to a solver with lower computational complexity than the standard multifrontal method for many applications, resulting in speedups up to 7 fold for problems in our test suite.more » The implementation targets many-core systems by using task parallelism with dynamic runtime scheduling. Numerical experiments show performance improvements over state-of-the-art sparse direct solvers. The implementation achieves high performance and good scalability on a range of modern shared memory parallel systems, including the Intel Xeon Phi (MIC). The code is part of a software package called STRUMPACK - STRUctured Matrices PACKage, which also has a distributed memory component for dense rank-structured matrices.« less

The spectra of reducible matrices over complete commutative idempotent semifields and their spectral lattices

NASA Astrophysics Data System (ADS)

José Valverde-Albacete, Francisco; Peláez-Moreno, Carmen

2016-02-01

Previous work has shown a relation between L-valued extensions of Formal Concept Analysis and the spectra of some matrices related to L-valued contexts. To clarify this relation, we investigated elsewhere the nature of the spectra of irreducible matrices over idempotent semifields in the framework of dioids, naturally ordered semirings, that encompass several of those extensions. This initial work already showed many differences with respect to their counterparts over incomplete idempotent semifields, in what concerns the definition of the spectrum and the eigenvectors. Considering special sets of eigenvectors also brought out complete lattices in the picture and we argue that such structure may be more important than standard eigenspace structure for matrices over completed idempotent semifields. In this paper, we complete that investigation in the sense that we consider the spectra of reducible matrices over completed idempotent semifields and dioids, giving, as a result, a constructive solution to the all-eigenvectors problem in this setting. This solution shows that the relation of complete lattices to eigenspaces is even tighter than suspected.

Individual Differences in General Intelligence Correlate with Brain Function during Nonreasoning Tasks.

ERIC Educational Resources Information Center

Haier, Richard J.; White, Nathan S.; Alkire, Michael T.

2003-01-01

Administered Raven's Advanced Progressive Matrices to 22 adults and measured cerebral glucose activity as subjects viewed videos on 2 occasions. Data provide evidence that individual differences in intelligence correlate with brain function even when the brain is engaged in non-reasoning tasks. (SLD)

Fluctuating Asymmetry and Intelligence

ERIC Educational Resources Information Center

Bates, Timothy C.

2007-01-01

The general factor of mental ability ("g") may reflect general biological fitness. If so, "g"-loaded measures such as Raven's progressive matrices should be related to morphological measures of fitness such as fluctuating asymmetry (FA: left-right asymmetry of a set of typically left-right symmetrical body traits such as finger…

Eye-Movement Analysis Demonstrates Strategic Influences on Intelligence

ERIC Educational Resources Information Center

Vigneau, Francois; Caissie, Andre F.; Bors, Douglas A.

2006-01-01

Taking into account various models and findings pertaining to the nature of analogical reasoning, this study explored quantitative and qualitative individual differences in intelligence using latency and eye-movement data. Fifty-five university students were administered 14 selected items of the Raven's Advanced Progressive Matrices test. Results…

Using a pruned, nondirect product basis in conjunction with the multi-configuration time-dependent Hartree (MCTDH) method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wodraszka, Robert, E-mail: Robert.Wodraszka@chem.queensu.ca; Carrington, Tucker, E-mail: Tucker.Carrington@queensu.ca

In this paper, we propose a pruned, nondirect product multi-configuration time dependent Hartree (MCTDH) method for solving the Schrödinger equation. MCTDH uses optimized 1D basis functions, called single particle functions, but the size of the standard direct product MCTDH basis scales exponentially with D, the number of coordinates. We compare the pruned approach to standard MCTDH calculations for basis sizes small enough that the latter are possible and demonstrate that pruning the basis reduces the CPU cost of computing vibrational energy levels of acetonitrile (D = 12) by more than two orders of magnitude. Using the pruned method, it ismore » possible to do calculations with larger bases, for which the cost of standard MCTDH calculations is prohibitive. Pruning the basis complicates the evaluation of matrix-vector products. In this paper, they are done term by term for a sum-of-products Hamiltonian. When no attempt is made to exploit the fact that matrices representing some of the factors of a term are identity matrices, one needs only to carefully constrain indices. In this paper, we develop new ideas that make it possible to further reduce the CPU time by exploiting identity matrices.« less

Miscellaneous methods for measuring matric or water potential

USGS Publications Warehouse

Scanlon, Bridget R.; Andraski, Brian J.; Bilskie, Jim; Dane, Jacob H.; Topp, G. Clarke

2002-01-01

A variety of techniques to measure matric potential or water potential in the laboratory and in the field are described in this section. The techniques described herein require equilibration of some medium whose matric or water potential can be determined from previous calibration or can be measured directly. Under equilibrium conditions the matric or water potential of the medium is equal to that of the soil. The techniques can be divided into: (i) those that measure matric potential and (ii) those that measure water potential (sum of matric and osmotic potentials). Matric potential is determined when the sensor matrix is in direct contact with the soil, so salts are free to diffuse in or out of the sensor matrix, and the equilibrium measurement therefore reflects matric forces acting on the water. Water potential is determined when the sensor is separated from the soil by a vapor gap, so salts are not free to move in or out of the sensor, and the equilibrium measurement reflects the sum of the matric and osmotic forces acting on the water.Seven different techniques are described in this section. Those that measure matric potential include (i) heat dissipation sensors, (ii) electrical resistance sensors, (iii) frequency domain and time domain sensors, and (iv) electro-optical switches. A method that can be used to measure matric potential or water potential is the (v) filter paper method. Techniques that measure water potential include (vi) the Dew Point Potentiameter (Decagon Devices, Inc., Pullman, WA1) (water activity meter) and (vii) vapor equilibration.The first four techniques are electronically based methods for measuring matric potential. Heat dissipation sensors and electrical resistance sensors infer matric potential from previously determined calibration relations between sensor heat dissipation or electrical resistance and matric potential. Frequency-domain and timedomain matric potential sensors measure water content, which is related to matric potential of the sensor through calibration. Electro-optical switches measure changes in light transmission through thin, nylon filters as they absorb or desorb water in response to changes in matric potential. Heat dissipation sensors and electrical resistance sensors are used primarily in the field to provide information on matric potential. Frequency domain matric potential sensors are new and have not been widely used. Time domain matric potential sensors and electro-optical switches are new and have not been commercialized. For the fifth technique, filter paper is used as the standard matrix. The filter paper technique measures matric potential when the filter paper is in direct contact with soil or water potential when separated from soil by a vapor gap. The Dew Point Potentiameter calculates water potential from the measured dew point and sample temperature. The vapor equilibration technique involves equilibration of soil samples with salt solutions of known osmotic potential. The filter paper, Dew Point Potentiameter, and vapor equilibration techniques are generally used in the laboratory to measure water potential of disturbed field samples or to measure water potential for water retention functions.

Development of a standard operating procedure for the collection of pyrethroids in water and sediment matrices

EPA Science Inventory

Through a Regional Applied Research Effort grant to the United States Geological Survey, Region 9 collaborated with ORD on this project to develop a standard operating procedure for collection of water and sediment samples for pyrethroid analysis.

A visual detection model for DCT coefficient quantization

NASA Technical Reports Server (NTRS)

Ahumada, Albert J., Jr.; Watson, Andrew B.

1994-01-01

The discrete cosine transform (DCT) is widely used in image compression and is part of the JPEG and MPEG compression standards. The degree of compression and the amount of distortion in the decompressed image are controlled by the quantization of the transform coefficients. The standards do not specify how the DCT coefficients should be quantized. One approach is to set the quantization level for each coefficient so that the quantization error is near the threshold of visibility. Results from previous work are combined to form the current best detection model for DCT coefficient quantization noise. This model predicts sensitivity as a function of display parameters, enabling quantization matrices to be designed for display situations varying in luminance, veiling light, and spatial frequency related conditions (pixel size, viewing distance, and aspect ratio). It also allows arbitrary color space directions for the representation of color. A model-based method of optimizing the quantization matrix for an individual image was developed. The model described above provides visual thresholds for each DCT frequency. These thresholds are adjusted within each block for visual light adaptation and contrast masking. For given quantization matrix, the DCT quantization errors are scaled by the adjusted thresholds to yield perceptual errors. These errors are pooled nonlinearly over the image to yield total perceptual error. With this model one may estimate the quantization matrix for a particular image that yields minimum bit rate for a given total perceptual error, or minimum perceptual error for a given bit rate. Custom matrices for a number of images show clear improvement over image-independent matrices. Custom matrices are compatible with the JPEG standard, which requires transmission of the quantization matrix.

The Complex Interaction between Home Environment, Socioeconomic Status, Maternal IQ and Early Child Neurocognitive Development: A Multivariate Analysis of Data Collected in a Newborn Cohort Study.

PubMed

Ronfani, Luca; Vecchi Brumatti, Liza; Mariuz, Marika; Tognin, Veronica; Bin, Maura; Ferluga, Valentina; Knowles, Alessandra; Montico, Marcella; Barbone, Fabio

2015-01-01

The relative role of socioeconomic status (SES), home environment and maternal intelligence, as factors affecting child cognitive development in early childhood is still unclear. The aim of this study is to analyze the association of SES, home environment and maternal IQ with child neurodevelopment at 18 months. The data were collected prospectively in the PHIME study, a newborn cohort study carried out in Italy between 2007 and 2010. Maternal nonverbal abilities (IQ) were evaluated using the Standard Progressive Matrices, a version of the Raven's Progressive Matrices; a direct evaluation of the home environment was carried out with the AIRE instrument, designed using the HOME (Home Observation for Measurement of the Environment) model; the socioeconomic characteristics were evaluated using the SES index which takes into account parents occupation, type of employment, educational level, homeownership. The study outcome was child neurodevelopment evaluated at 18 months, with the Bayley Scales of Infant and Toddler Development Third Edition (BSID III). Linear regression analyses and mediation analyses were carried out to evaluate the association between the three exposures, and the scaled scores of the three main scales of BSID III (cognitive, language and motor scale), with adjustment for a wide range of potential explanatory variables. Data from 502 mother-child pairs were analyzed. Mediation analysis showed a relationship between SES and maternal IQ, with a complete mediation effect of home environment in affecting cognitive and language domains. A direct significant effect of maternal IQ on the BSID III motor development scale and the mediation effect of home environment were found. Our results show that home environment was the variable with greater influence on neurodevelopment at 18 months. The observation of how parents and children interact in the home context is crucial to adequately evaluate early child development.

A non-verbal technique for the assessment of general intellectual ability in selection of aviation personnel.

DOT National Transportation Integrated Search

1971-06-01

A study was conducted in which performance on a non-verbal problem- solving task was correlated with the Otis Quick Scoring Mental Ability Test and the Raven Progressive Matrices Test. The problem-solving task, called 'code- lock' required the subjec...

The Relationships between Cognitive Ability and Dynamic Decision Making

ERIC Educational Resources Information Center

Gonzalez, C.; Thomas, R.P.; Vanyukov, P.

2005-01-01

This study investigated the relationships between cognitive ability (as assessed by the Raven Progressive Matrices Test [RPM] and the Visual-Span Test [VSPAN]) and individuals' performance in three dynamic decision making (DDM) tasks (i.e., regular Water Purification Plant [WPP], Team WPP, and Firechief). Participants interacted repeatedly with…

Proactive Interference and Item Similarity in Working Memory

ERIC Educational Resources Information Center

Bunting, Michael

2006-01-01

Proactive interference (PI) may influence the predictive utility of working memory span tasks. Participants in one experiment (N=70) completed Ravens Advanced Progressive Matrices (RAPM) and multiple versions of operation span and probed recall, modified for the type of memoranda (digits or words). Changing memoranda within- or across-trials…

Intellectual Estimates of Hearing-Impaired Children: A Comparison of Three Measures

ERIC Educational Resources Information Center

Ritter, David R.

1976-01-01

The Arthur Adaptation of the Leiter International Performance Scale, Raven's Coloured Progressive Matrices, and Wechsler Intelligence Scale for Children-Performance Section were administered to 31 children with mild to moderate hearing impairments. A comparison of test results indicated moderate convergent validity among the measures. (Author)

Embodied, Symbolic and Formal Thinking in Linear Algebra

ERIC Educational Resources Information Center

Stewart, Sepideh; Thomas, Michael O. J.

2007-01-01

Students often find their first university linear algebra experience very challenging. While coping with procedural aspects of the subject, solving linear systems and manipulating matrices, they may struggle with crucial conceptual ideas underpinning them, making it very difficult to progress in more advanced courses. This research has sought to…

Problems with IQ Gains: The Huge Vocabulary Gap

ERIC Educational Resources Information Center

Flynn, James R.

2010-01-01

Despite Kaufman, Raven's Progressive Matrices and the Wechsler subtest Similarities are tests whose gains call for special explanation. The spread of "scientific spectacles" is the key, but its explanatory potential has been exhausted. Three trends force us to look elsewhere: (a) gains on Wechsler subtests such as Picture Arrangement,…

Validation of standard method EN ISO 11290-part 2 for the enumeration of Listeria monocytogenes in food.

PubMed

Rollier, Patricia; Lombard, Bertrand; Guillier, Laurent; François, Danièle; Romero, Karol; Pierru, Sylvie; Bouhier, Laurence; Gnanou Besse, Nathalie

2018-05-01

The reference method for the detection and enumeration of L. monocytogenes in food (Standards EN ISO 11290-1&2) have been validated by inter-laboratory studies in the frame of the Mandate M381 from European Commission to CEN. In this paper, the inter-laboratory studies led in 2013 on 5 matrices (cold-smoked salmon, milk powdered infant food formula, vegetables, environment, and cheese) to validate Standard EN ISO 11290-2 are reported. According to the results obtained, the method of the revised Standard EN ISO 11290-2 can be considered as a good method for the enumeration of L. monocytogenes in foods and food processing environment, in particular for the matrices included in the study. Values of repeatability and reproducibility standard deviations can be considered satisfactory for this type of method with a confirmation stage, since most of them were below 0.3 log 10 , also at low levels, close to the regulatory limit of 100 CFU/g. Copyright © 2018 Elsevier B.V. All rights reserved.

Emerging spectra of singular correlation matrices under small power-map deformations

NASA Astrophysics Data System (ADS)

Vinayak; Schäfer, Rudi; Seligman, Thomas H.

2013-09-01

Correlation matrices are a standard tool in the analysis of the time evolution of complex systems in general and financial markets in particular. Yet most analysis assume stationarity of the underlying time series. This tends to be an assumption of varying and often dubious validity. The validity of the assumption improves as shorter time series are used. If many time series are used, this implies an analysis of highly singular correlation matrices. We attack this problem by using the so-called power map, which was introduced to reduce noise. Its nonlinearity breaks the degeneracy of the zero eigenvalues and we analyze the sensitivity of the so-emerging spectra to correlations. This sensitivity will be demonstrated for uncorrelated and correlated Wishart ensembles.

Emerging spectra of singular correlation matrices under small power-map deformations.

PubMed

Vinayak; Schäfer, Rudi; Seligman, Thomas H

2013-09-01

Correlation matrices are a standard tool in the analysis of the time evolution of complex systems in general and financial markets in particular. Yet most analysis assume stationarity of the underlying time series. This tends to be an assumption of varying and often dubious validity. The validity of the assumption improves as shorter time series are used. If many time series are used, this implies an analysis of highly singular correlation matrices. We attack this problem by using the so-called power map, which was introduced to reduce noise. Its nonlinearity breaks the degeneracy of the zero eigenvalues and we analyze the sensitivity of the so-emerging spectra to correlations. This sensitivity will be demonstrated for uncorrelated and correlated Wishart ensembles.

An implementation of the look-ahead Lanczos algorithm for non-Hermitian matrices, part 1

NASA Technical Reports Server (NTRS)

Freund, Roland W.; Gutknecht, Martin H.; Nachtigal, Noel M.

1990-01-01

The nonsymmetric Lanczos method can be used to compute eigenvalues of large sparse non-Hermitian matrices or to solve large sparse non-Hermitian linear systems. However, the original Lanczos algorithm is susceptible to possible breakdowns and potential instabilities. We present an implementation of a look-ahead version of the Lanczos algorithm which overcomes these problems by skipping over those steps in which a breakdown or near-breakdown would occur in the standard process. The proposed algorithm can handle look-ahead steps of any length and is not restricted to steps of length 2, as earlier implementations are. Also, our implementation has the feature that it requires roughly the same number of inner products as the standard Lanczos process without look-ahead.

Weighted network analysis of high-frequency cross-correlation measures

NASA Astrophysics Data System (ADS)

Iori, Giulia; Precup, Ovidiu V.

2007-03-01

In this paper we implement a Fourier method to estimate high-frequency correlation matrices from small data sets. The Fourier estimates are shown to be considerably less noisy than the standard Pearson correlation measures and thus capable of detecting subtle changes in correlation matrices with just a month of data. The evolution of correlation at different time scales is analyzed from the full correlation matrix and its minimum spanning tree representation. The analysis is performed by implementing measures from the theory of random weighted networks.

Solvent-induced dimensional changes in EDTA-demineralized dentin matrix.

PubMed

Pashley, D H; Agee, K A; Nakajima, M; Tay, F R; Carvalho, R M; Terada, R S; Harmon, F J; Lee, W K; Rueggeberg, F A

2001-08-01

The purpose of this study was to test the null hypothesis that the re-expansion of dried matrix and the shrinkage of moist, demineralized dentin is not influenced by polar solvents. Dentin disks were prepared from midcoronal dentin of extracted human third molars. After complete demineralization in 0.5M of EDTA (pH 7), the specimens were placed in the well of a device that measures changes in matrix height in real time. Dry, collapsed matrices were created by blowing dry N(2) on the specimens until they shrank to a stable plateau. Polar solvents [water, methanol, ethanol, n-propanol, n-butanol, formamide, ethylene glycol, hydroxyethyl methacrylate (HEMA), or mixtures of water-HEMA] as model primers then were added and the degree of re-expansion measured. These same solvents also were applied to moist, expanded matrices and the solvent-induced shrinkages measured. Regression analysis was used to test the correlations between matrix height and Hansen's dispersive, polar, hydrogen bonding, and total solubility parameters (delta(d), delta(p), delta(h), delta(t)). The results indicate that water-free polar solvents of low hydrogen bonding (H-bond) ability (e.g., neat HEMA) do not re-expand dried matrices and that they shrink moist matrices. When HEMA was mixed with progressively higher water concentrations, the model water-HEMA primers expanded the dried matrix in proportion to their water concentrations and they produced less shrinkage of moist matrices. Solvents with higher H-bonding capacities (methanol, ethanol, ethylene glycol, formamide, and water) re-expanded the dried matrix in proportion to their solubility parameters for H-bonding (delta(h)). They also induced small transient shrinkages of moist matrices, which slowly re-expanded. The results require rejection of the null hypothesis. Copyright 2001 John Wiley & Sons, Inc. J Biomed Mater Res 56: 273-281, 2001

Analysis of Trace Quaternary Ammonium Compounds (QACs) in Vegetables Using Ultrasonic-Assisted Extraction and Gas Chromatography-Mass Spectrometry.

PubMed

Xiang, Lei; Wang, Xiong-Ke; Li, Yan-Wen; Huang, Xian-Pei; Wu, Xiao-Lian; Zhao, Hai-Ming; Li, Hui; Cai, Quan-Ying; Mo, Ce-Hui

2015-08-05

A reliable, sensitive, and cost-effective method was developed for determining three quaternary ammonium compounds (QACs) including dodecyltrimethylammonium chloride, cetyltrimethylammonium chloride, and didodecyldimethylammonium chloride in various vegetables using ultrasonic-assisted extraction and gas chromatography-mass spectrometry. The variety and acidity of extraction solvents, extraction times, and cleanup efficiency of sorbents were estimated to obtain an optimized procedure for extraction of the QACs in nine vegetable matrices. Excellent linearities (R(2) > 0.992) were obtained for the analytes in the nine matrices. The limits of detection and quantitation were 0.7-6.0 and 2.3-20.0 μg/kg (dry weight, dw) in various matrices, respectively. The recoveries in the nine matrices ranged from 70.5% to 108.0% with relative standard deviations below 18.0%. The developed method was applied to determine the QACs in 27 vegetable samples collected from Guangzhou in southern China, showing very high detection frequency with a concentration of 23-180 μg/kg (dw).

On the extreme value statistics of normal random matrices and 2D Coulomb gases: Universality and finite N corrections

NASA Astrophysics Data System (ADS)

Ebrahimi, R.; Zohren, S.

2018-03-01

In this paper we extend the orthogonal polynomials approach for extreme value calculations of Hermitian random matrices, developed by Nadal and Majumdar (J. Stat. Mech. P04001 arXiv:1102.0738), to normal random matrices and 2D Coulomb gases in general. Firstly, we show that this approach provides an alternative derivation of results in the literature. More precisely, we show convergence of the rescaled eigenvalue with largest modulus of a normal Gaussian ensemble to a Gumbel distribution, as well as universality for an arbitrary radially symmetric potential. Secondly, it is shown that this approach can be generalised to obtain convergence of the eigenvalue with smallest modulus and its universality for ring distributions. Most interestingly, the here presented techniques are used to compute all slowly varying finite N correction of the above distributions, which is important for practical applications, given the slow convergence. Another interesting aspect of this work is the fact that we can use standard techniques from Hermitian random matrices to obtain the extreme value statistics of non-Hermitian random matrices resembling the large N expansion used in context of the double scaling limit of Hermitian matrix models in string theory.

A TANDEM SUPERCRITICAL FLUID EXTRACTION (SFE) AND LIQUID CHROMATOGRAPHY (LC) SYSTEM FOR DETERMINATION OF CHLORINATED PHENOLS IN SOLID MATRICES. (R825549C011)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

COMPARISON OF THE SOLID-MATRIX LUMINESCENCE PROPERTIES OF B[A]P-DNA ADDUCTS ON ALPHA-CYCLODEXTRIN/NACL AND TREHALOSE/NACL MATRICES. (R824100)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

Intelligence and Metacognition as Predictors of Foreign Language Achievement: A Structural Equation Modeling Approach

ERIC Educational Resources Information Center

Pishghadam, Reza; Khajavy, Gholam Hassan

2013-01-01

This study examined the role of metacognition and intelligence in foreign language achievement on a sample of 143 Iranian English as a Foreign Language (EFL) learners. Participants completed Raven's Advanced Progressive Matrices as a measure of intelligence, and Metacognitive Awareness Inventory as a measure of metacognition. Learners' scores at…

Relationships between Visual and Auditory Perceptual Skills and Comprehension in Students with Learning Disabilities.

ERIC Educational Resources Information Center

Weaver, Phyllis A.; Rosner, Jerome

1979-01-01

Scores of 25 learning disabled students (aged 9 to 13) were compared on five tests: a visual-perceptual test (Coloured Progressive Matrices); an auditory-perceptual test (Auditory Motor Placement); a listening and reading comprehension test (Durrell Listening-Reading Series); and a word recognition test (Word Recognition subtest, Diagnostic…

Superior Nonverbal Intelligence in Children with High-Functioning Autism or Asperger's Syndrome

ERIC Educational Resources Information Center

Chen, Fei; Planche, Pascale; Lemonnier, Eric

2010-01-01

Some early studies showed discordance in cognitive strengths and weaknesses in individuals with high-functioning autism (HFA) or Asperger's syndrome (AS). The present study administered the French version of Colored Raven's Progressive Matrices in 14 children with HFA/AS and in 26 chronological age matched peers with typical development. We found…

Cerebral Lateralization and General Intelligence: Gender Differences in a Transcranial Doppler Study

ERIC Educational Resources Information Center

Njemanze, P.C.

2005-01-01

The present study evaluated cerebral lateralization during Raven's progressive matrices (RPM) paradigm in female and male subjects. Bilateral simultaneous transcranial Doppler (TCD) ultrasound was used to measure mean blood flow velocities (MBFV) in the right and left middle cerebral arteries (MCAs) in 24 (15 females and 9 males) right-handed…

Biophysical force regulation in 3D tumor cell invasion

NASA Astrophysics Data System (ADS)

Wu, Mingming

When embedded within 3D extracellular matrices (ECM), animal cells constantly probe and adapt to the ECM locally (at cell length scale) and exert forces and communicate with other cells globally (up to 10 times of cell length). It is now well accepted that mechanical crosstalk between animal cells and their microenvironment critically regulate cell function such as migration, proliferation and differentiation. Disruption of the cell-ECM crosstalk is implicated in a number of pathologic processes including tumor progression and fibrosis. Central to the problem of cell-ECM crosstalk is the physical force that cells generate. By measuring single cell generated force within 3D collagen matrices, we revealed a mechanical crosstalk mechanism between the tumor cells and the ECM. Cells generate sufficient force to stiffen collagen fiber network, and stiffer matrix, in return promotes larger cell force generation. Our work highlights the importance of fibrous nonlinear elasticity in regulating tumor cell-ECM interaction, and results may have implications in the rapid tissue stiffening commonly found in tumor progression and fibrosis. This work is partially supported by NIH Grants R21RR025801 and R21GM103388.

Problem solving ability in children with intellectual disability as measured by the Raven's colored progressive matrices.

PubMed

Goharpey, Nahal; Crewther, David P; Crewther, Sheila G

2013-12-01

This study investigated the developmental trajectory of problem solving ability in children with intellectual disability (ID) of different etiologies (Down Syndrome, Idiopathic ID or low functioning Autism) as measured on the Raven's Colored Progressive Matrices test (RCPM). Children with typical development (TD) and children with ID were matched on total correct performance (i.e., non-verbal mental age) on the RCPM. RCPM total correct performance and the sophistication of error types were found to be associated with receptive vocabulary in all participants, suggesting that verbal ability plays a role in more sophisticated problem solving tasks. Children with ID made similar errors on the RCPM as younger children with TD as well as more positional error types. This result suggests that children with ID who are deficient in their cognitive processing resort to developmentally immature problem solving strategies when unable to determine the correct answer. Overall, the findings support the use of RCPM as a valid means of matching intellectual capacity of children with TD and ID. Copyright © 2013 Elsevier Ltd. All rights reserved.

Gender-related decrease in raven`s progressive matrices scores in children prenatally exposed to polychlorinated biphenyls and related contaminants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Y.L.; Lai, T.J.; Chen, S.J.

1995-07-01

Polychlorinated biphenyls (PCBs) and industrial mixtures that have been widely used throughout the world. PCBs have long environmental half lives and bioconcentrate, therefore contaminating soil, water, wild life, and human tissues. Typical human exposures come from environmental contamination of food supply, especially fresh water fish and meat, and occupational exposures. In certain uses, PCBs can partially oxidize and themselves become contaminated by extremely toxic compounds such as polychlorinated dibenzofurans (PCDFs). Two episodes of intoxication with heat-degraded PCBs have occurred, in Japan and Taiwan respectively. In 1979, over 2000 persons in Taiwan were intoxicated by heat-degraded PCBs that had contaminated theirmore » cooking oil. Kaneclor 500 (a Japanese PCB mixture) contained in the heating pipe was used as the heat transmitter. Leakage of the pipe introduced PCBs and heat-degraded products such as polychlorinated dibenzofurans (PCDFs) and polychlorinated quaterphenyls (PCQs) into the rice oil. Exposed victims developed chloracne, hyperpigmentation, peripheral neuropathy, and other signs and symptoms which were later called Yu-Cheng ({open_quotes}oil disease{close_quotes}) in Taiwan. These symptoms were caused not only by PCBs but by their heat degraded products, PCDFs. PCBs, PCDFs and PCDDs also can cross the placenta to affect the fetus and cause significant neurodevelopmental toxicity. Raven`s Colored Progressive Matrices (CPM) and Standarized Progressive Matrices (SPM) test spatial rather than verbal capabilities in children. These test are useful for determining whether prenatal exposure to PCBs/PCDFs cause differential effects on boys and girls. This paper reports results of CPM and SPM from age six to nine year in Yu-Cheng children and their matched controls. Cognative deficits up to 9 years of age were detected n children with prenatal exposure to PCBs and PCDFs, and boys were more affected than girls. 26 refs., 1 fig., 2 tabs.« less

Raman spectra of ruthenium and tantalum trimers in argon matrices

NASA Astrophysics Data System (ADS)

Fang, Li; Shen, Xiaole; Chen, Xiaoyu; Lombardi, John R.

2000-12-01

The resonance Raman spectra of ruthenium trimers (Ru 3) in argon matrices have been obtained. Three resonance Raman transitions were observed between 570 and 590 nm. Two of them (303.4 and 603.7 cm -1) are assigned to the totally symmetric vibrational progression, giving k e=1.86 mdyne/ Å. The line at 581.5 cm-1 is assigned as the origin of a low-lying electronic state. We also report on the observation of a resonance Raman spectrum of tantalum trimers (Ta 3). Observed lines include 251.2 and 501.9 cm-1 which we assign to the fundamental and the first overtone of the symmetric stretch in Ta 3. This gives k e=2.25 mdyne/ Å.

Novel formulations of CKM matrix renormalization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kniehl, Bernd A.; Sirlin, Alberto

2009-12-17

We review two recently proposed on-shell schemes for the renormalization of the Cabibbo-Kobayashi-Maskawa (CKM) quark mixing matrix in the Standard Model. One first constructs gauge-independent mass counterterm matrices for the up- and down-type quarks complying with the hermiticity of the complete mass matrices. Diagonalization of the latter then leads to explicit expressions for the CKM counterterm matrix, which are gauge independent, preserve unitarity, and lead to renormalized amplitudes that are non-singular in the limit in which any two quarks become mass degenerate. One of the schemes also automatically satisfies flavor democracy.

The Development and Application of Intelligence Tests for the Blind: A Research Utilization Conference. Final Report.

ERIC Educational Resources Information Center

Georgia Univ., Athens. Div. for Exceptional Children.

Reported are the proceedings and recommendations of a research conference to improve the development and utilization of intelligence tests for use with blind adults in social and vocational rehabilitation. The following tests are considered: A Haptic Intelligence Scale for the Adult Blind, the Raven Progressive Matrices for Presentation to the…

Working Memory Training Does Not Improve Intelligence in Healthy Young Adults

ERIC Educational Resources Information Center

Chooi, Weng-Tink; Thompson, Lee A.

2012-01-01

Jaeggi and her colleagues claimed that they were able to improve fluid intelligence by training working memory. Subjects who trained their working memory on a dual n-back task for a period of time showed significant improvements in working memory span tasks and fluid intelligence tests such as the Raven's Progressive Matrices and the Bochumer…

Analysis of the Raven CPM Subtest Scores for a Sample of Gifted Children.

ERIC Educational Resources Information Center

Kluever, Raymond C.; Green, Kathy E.

The inter-subject/intra-subject subtest patterns (profiles) of the same sample of gifted children were examined based on factors found in a previous study of the Raven Coloured Progressive Matrices Test (CPM) that investigated structural properties with specific application to a sample of gifted children. The sample consisted of 166 children (78…

Cognitive Processes and Math Performance: A Study with Children at Third Grade of Basic Education

ERIC Educational Resources Information Center

Campos, Isabel S.; Almeida, Leandro S.; Ferreira, Aristides I.; Martinez, Luis F.; Ramalho, Gloria

2013-01-01

The present study aims to examine the relationship between cognitive factors and mathematical achievement in primary education. Participants were 103 Portuguese third grade students, aged 8 and 9. All participants completed a battery for working memory (WMTB-C), a test of general intelligence (Raven's Progressive Color Matrices), a selective…

LASER-INDUCED MULTIDIMENSIONAL FLUORESCENCE SPECTROSCOPY IN SHPOL'SKII MATRICES FOR THE ANALYSIS OF POLYCYCLIC AROMATIC HYDROCARBONS IN HPLC FRACTIONS AND COMPLEX ENVIRONMENTAL EXTRACTS. (R828081E01)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

Intellectual Growth in Children as a Function of Domain Specific and Domain General Working Memory Subgroups

ERIC Educational Resources Information Center

Swanson, H. Lee

2011-01-01

This study examined whether children's growth on measures of fluid (Raven Colored Progressive Matrices) and crystallized (reading and math achievement) intelligence was attributable to domain-specific or domain-general functions of working memory (WM). A sample of 290 elementary school children was tested on measures of intelligence across three…

Brief Report: The Level and Nature of Autistic Intelligence Revisited

ERIC Educational Resources Information Center

Bolte, Sven; Dziobek, Isabel; Poustka, Fritz

2009-01-01

Owing to higher performance on the Raven's Progressive Matrices (RPM) than on the Wechsler Intelligence Scales (WIS), it has recently been argued that intelligence is underestimated in autism. This study examined RPM and WIS IQs in 48 individuals with autism, a mixed clinical (n = 28) and a neurotypical (n = 25) control group. Average RPM IQ was…

More about unphysical zeroes in quark mass matrices

NASA Astrophysics Data System (ADS)

Emmanuel-Costa, David; González Felipe, Ricardo

2017-01-01

We look for all weak bases that lead to texture zeroes in the quark mass matrices and contain a minimal number of parameters in the framework of the standard model. Since there are ten physical observables, namely, six nonvanishing quark masses, three mixing angles and one CP phase, the maximum number of texture zeroes in both quark sectors is altogether nine. The nine zero entries can only be distributed between the up- and down-quark sectors in matrix pairs with six and three texture zeroes or five and four texture zeroes. In the weak basis where a quark mass matrix is nonsingular and has six zeroes in one sector, we find that there are 54 matrices with three zeroes in the other sector, obtainable through right-handed weak basis transformations. It is also found that all pairs composed of a nonsingular matrix with five zeroes and a nonsingular and nondecoupled matrix with four zeroes simply correspond to a weak basis choice. Without any further assumptions, none of these pairs of up- and down-quark mass matrices has physical content. It is shown that all non-weak-basis pairs of quark mass matrices that contain nine zeroes are not compatible with current experimental data. The particular case of the so-called nearest-neighbour-interaction pattern is also discussed.

Quantitative mass spectrometry of unconventional human biological matrices

NASA Astrophysics Data System (ADS)

Dutkiewicz, Ewelina P.; Urban, Pawel L.

2016-10-01

The development of sensitive and versatile mass spectrometric methodology has fuelled interest in the analysis of metabolites and drugs in unconventional biological specimens. Here, we discuss the analysis of eight human matrices-hair, nail, breath, saliva, tears, meibum, nasal mucus and skin excretions (including sweat)-by mass spectrometry (MS). The use of such specimens brings a number of advantages, the most important being non-invasive sampling, the limited risk of adulteration and the ability to obtain information that complements blood and urine tests. The most often studied matrices are hair, breath and saliva. This review primarily focuses on endogenous (e.g. potential biomarkers, hormones) and exogenous (e.g. drugs, environmental contaminants) small molecules. The majority of analytical methods used chromatographic separation prior to MS; however, such a hyphenated methodology greatly limits analytical throughput. On the other hand, the mass spectrometric methods that exclude chromatographic separation are fast but suffer from matrix interferences. To enable development of quantitative assays for unconventional matrices, it is desirable to standardize the protocols for the analysis of each specimen and create appropriate certified reference materials. Overcoming these challenges will make analysis of unconventional human biological matrices more common in a clinical setting. This article is part of the themed issue 'Quantitative mass spectrometry'.

Wall-crossing invariants: from quantum mechanics to knots

DOE Office of Scientific and Technical Information (OSTI.GOV)

Galakhov, D., E-mail: galakhov@itep.ru, E-mail: galakhov@physics.rutgers.edu; Mironov, A., E-mail: mironov@lpi.ru; Morozov, A., E-mail: morozov@itep.ru

2015-03-15

We offer a pedestrian-level review of the wall-crossing invariants. The story begins from the scattering theory in quantum mechanics where the spectrum reshuffling can be related to permutations of S-matrices. In nontrivial situations, starting from spin chains and matrix models, the S-matrices are operatorvalued and their algebra is described in terms of R- and mixing (Racah) U-matrices. Then the Kontsevich-Soibelman (KS) invariants are nothing but the standard knot invariants made out of these data within the Reshetikhin-Turaev-Witten approach. The R and Racah matrices acquire a relatively universal form in the semiclassical limit, where the basic reshufflings with the change ofmore » moduli are those of the Stokes line. Natural from this standpoint are matrices provided by the modular transformations of conformal blocks (with the usual identification R = T and U = S), and in the simplest case of the first degenerate field (2, 1), when the conformal blocks satisfy a second-order Shrödinger-like equation, the invariants coincide with the Jones (N = 2) invariants of the associated knots. Another possibility to construct knot invariants is to realize the cluster coordinates associated with reshufflings of the Stokes lines immediately in terms of check-operators acting on solutions of the Knizhnik-Zamolodchikov equations. Then the R-matrices are realized as products of successive mutations in the cluster algebra and are manifestly described in terms of quantum dilogarithms, ultimately leading to the Hikami construction of knot invariants.« less

Psychoticism and disruptive behavior can be also good predictors of school achievement.

PubMed

Flores-Mendoza, Carmen; Widaman, Keith; Mansur-Alves, Marcela; Bacelar, Tatiane Dias; Saldanha, Renata

2013-01-01

The relations of Gf (Standard Progressive Matrices Raven), Gc (verbal scale of Wechsler Intelligence Scale for Children-Third Version), personality dimensions (Eysenck Personality Questionnaire-Junior Version), and disruptive behavior (TDAH scale) with school achievement (measured by TDE test and PISA test) were investigated. Two samples of students (total N = 534) representing a broad range of socioeconomic status (SES) participated in this study. Path models were conducted. The results demonstrated that (1) in both samples no sex differences related to school achievement were found; (2) in the first sample, after controlling for age and SES differences, Gf and psychoticism predicted (.38 and -.13, respectively) school achievement (measured by TDE test); (3) in the second sample, after controlling for SES differences to which additional measures were administered, Gf and Gc positively predicted (.22 and .40, respectively) school achievement (measured by PISA test). In addition, psychoticism and disruptive behavior also predicted school performance (-.14 and -.28, respectively). Some theoretical and practical implications are discussed.

Finding workers, offenders, or students most at-risk for violence: actuarial tests save lives and resources.

PubMed

Zagar, Robert John; Kovach, Joseph W; Basile, Benjamin; Hughes, John Russell; Grove, William M; Busch, Kenneth G; Zablocki, Michael; Osnowitz, William; Neuhengen, Jonas; Liu, Yutong; Zagar, Agata Karolina

2013-12-01

147 adults (107 men, 40 women) and 89 adolescents (61 boys, 28 girls), selected randomly from referrals and volunteers, were given the Ammons Quick Test (QT), the Beck Suicide Scale (BSS), the Minnesota Multiphasic Personality Inventory Second (MMPI-2) or Adolescent Versions (MMPI-A), the Raven's Advanced Progressive Matrices, and the Standard Predictor (SP) of Violence Potential Adult or Adolescent Versions. The goals were to: (a) demonstrate computer and paper-and-pencil tests correlated; (b) validate tests to identify at-risk for violence; (c) show that identifying at-risk saves lives and resources; and (d) find which industries benefited from testing at-risk. Paper-and-pencil vs. computer test correlations (.83-.99), sensitivity (.97-.98), and specificity (.50-.97) were computed. Testing at-risk saves lives and resources. Critical industries for testing at-risk individuals may include airlines, energy generating industries, insurance, military, nonprofit-religious, prisoners, trucking or port workers, and veterans.

Evidence-based alternatives for autogenous grafts around teeth: outcomes, attachment, and stability.

PubMed

McGuire, Michael K

2014-06-01

Although the use of autogenous harvested tissues has proven to be the gold standard for soft tissue augmentation procedures involving root coverage or generation of keratinized tissue, harvest site morbidity and limited supply have prompted clinicians to seek graft alternatives. Using a hierarchy of evidence, the author reviews both clinical and patient-reported results for harvest graft substitutes and, considering his own research experience, reviews autogenous graft substitute outcomes, attachment, and stability over time. Overall, when the goal is keratinized-tissue generation, living cellular constructs and xenogeneic collagen matrices have provided acceptable clinical results, but with better esthetics and patient preference than autogenous free gingival grafts. For root coverage therapy, enamel matrix derivatives, platelet-derived growth factors, and xenogeneic collagen matrices have provided acceptable results with equivalent esthetics to autogenous connective tissue grafts, while also being preferred by patients. Longterm results for enamel matrix derivatives, platelet-derived growth factors, and xenogeneic collagen matrices indicate root coverage can be maintained over time. In the author's hands, xenogeneic collagen matrices have been the only harvest graft alternatives that can be used either covered or uncovered by soft tissue.

Matrix effects on organic pollutants analysis in marine sediment

NASA Astrophysics Data System (ADS)

Azis, M. Y.; Asia, L.; Piram, A.; Buchari, B.; Doumenq, P.; Setiyanto, H.

2018-05-01

Interference from the matrix sample can influence of the accurate analytical method. Accelerated Solvent Extraction and their purification methods were tried to separate the organic micropollutants respectively in marine sediment. Those matrix were as organic pollutants evaluation in marine environment. Polychlorinated Biphenyls (PCBs) and Organochlorine pesticides (OCPs) are two examples organic pollutant in environment which are carcinogenic and mutagenic. Marine sediments are important matrices of information regarding the human activities in coastal areas as well as the fate and behavior of organic pollutants, which are persistent in long-term. This research purpose to evaluate the matrice effect and the recovery from marine sediment spiking with several standar solution and deuterium of molecular target from organic pollutants in not polluted sample of sediment. Matrice samples was tested from indicate in unpolluted location. The methods were evaluated with standard calibration curve (linearity < 0.999, LOQ various ranged 0.5-1000 pg.μL-1 and LOD > LOQ). Recovery (YE) relative, Matrice Effect (ME) relative correction with deuteriated standar were evaluated the interference the matrix. Interference effect for OCPs compounds were higher than PCBs in marine sediment.

Real-Time Cytotoxicity Assay for Rapid and Sensitive Detection of Ricin from Complex Matrices

PubMed Central

Pauly, Diana; Worbs, Sylvia; Kirchner, Sebastian; Shatohina, Olena; Dorner, Martin B.; Dorner, Brigitte G.

2012-01-01

Background In the context of a potential bioterrorist attack sensitive and fast detection of functionally active toxins such as ricin from complex matrices is necessary to be able to start timely countermeasures. One of the functional detection methods currently available for ricin is the endpoint cytotoxicity assay, which suffers from a number of technical deficits. Methodology/Findings This work describes a novel online cytotoxicity assay for the detection of active ricin and Ricinus communis agglutinin, that is based on a real-time cell electronic sensing system and impedance measurement. Characteristic growth parameters of Vero cells were monitored online and used as standardized viability control. Upon incubation with toxin the cell status and the cytotoxic effect were visualized using a characteristic cell index–time profile. For ricin, tested in concentrations of 0.06 ng/mL or above, a concentration-dependent decrease of cell index correlating with cytotoxicity was recorded between 3.5 h and 60 h. For ricin, sensitive detection was determined after 24 h, with an IC50 of 0.4 ng/mL (for agglutinin, an IC50 of 30 ng/mL was observed). Using functionally blocking antibodies, the specificity for ricin and agglutinin was shown. For detection from complex matrices, ricin was spiked into several food matrices, and an IC50 ranging from 5.6 to 200 ng/mL was observed. Additionally, the assay proved to be useful in detecting active ricin in environmental sample materials, as shown for organic fertilizer containing R. communis material. Conclusions/Significance The cell-electrode impedance measurement provides a sensitive online detection method for biologically active cytotoxins such as ricin. As the cell status is monitored online, the assay can be standardized more efficiently than previous approaches based on endpoint measurement. More importantly, the real-time cytotoxicity assay provides a fast and easy tool to detect active ricin in complex sample matrices. PMID:22532852

Second-order standard addition for deconvolution and quantification of fatty acids of fish oil using GC-MS.

PubMed

Vosough, Maryam; Salemi, Amir

2007-08-15

In the present work two second-order calibration methods, generalized rank annihilation method (GRAM) and multivariate curve resolution-alternating least square (MCR-ALS) have been applied on standard addition data matrices obtained by gas chromatography-mass spectrometry (GC-MS) to characterize and quantify four unsaturated fatty acids cis-9-hexadecenoic acid (C16:1omega7c), cis-9-octadecenoic acid (C18:1omega9c), cis-11-eicosenoic acid (C20:1omega9) and cis-13-docosenoic acid (C22:1omega9) in fish oil considering matrix interferences. With these methods, the area does not need to be directly measured and predictions are more accurate. Because of non-trilinear conditions of GC-MS data matrices, at first MCR-ALS and GRAM have been used on uncorrected data matrices. In comparison to MCR-ALS, biased and imprecise concentrations (%R.S.D.=27.3) were obtained using GRAM without correcting the retention time-shift. As trilinearity is the essential requirement for implementing GRAM, the data need to be corrected. Multivariate rank alignment objectively corrects the run-to-run retention time variations between sample GC-MS data matrix and a standard addition GC-MS data matrix. Then, two second-order algorithms have been compared with each other. The above algorithms provided similar mean predictions, pure concentrations and spectral profiles. The results validated using standard mass spectra of target compounds. In addition, some of the quantification results were compared with the concentration values obtained using the selected mass chromatograms. As in the case of strong peak-overlap and the matrix effect, the classical univariate method of determination of the area of the peaks of the analytes will fail, the "second-order advantage" has solved this problem successfully.

Evaluation of human acellular dermis versus porcine acellular dermis in an in vivo model for incisional hernia repair.

PubMed

Ngo, Manh-Dan; Aberman, Harold M; Hawes, Michael L; Choi, Bryan; Gertzman, Arthur A

2011-05-01

Incisional hernias commonly occur following abdominal wall surgery. Human acellular dermal matrices (HADM) are widely used in abdominal wall defect repair. Xenograft acellular dermal matrices, particularly those made from porcine tissues (PADM), have recently experienced increased usage. The purpose of this study was to compare the effectiveness of HADM and PADM in the repair of incisional abdominal wall hernias in a rabbit model. A review from earlier work of differences between human allograft acellular dermal matrices (HADM) and porcine xenograft acellular dermal matrices (PADM) demonstrated significant differences (P < 0.05) in mechanical properties: Tensile strength 15.7 MPa vs. 7.7 MPa for HADM and PADM, respectively. Cellular (fibroblast) infiltration was significantly greater for HADM vs. PADM (Armour). The HADM exhibited a more natural, less degraded collagen by electrophoresis as compared to PADM. The rabbit model surgically established an incisional hernia, which was repaired with one of the two acellular dermal matrices 3 weeks after the creation of the abdominal hernia. The animals were euthanized at 4 and 20 weeks and the wounds evaluated. Tissue ingrowth into the implant was significantly faster for the HADM as compared to PADM, 54 vs. 16% at 4 weeks, and 58 vs. 20% for HADM and PADM, respectively at 20 weeks. The original, induced hernia defect (6 cm(2)) was healed to a greater extent for HADM vs. PADM: 2.7 cm(2) unremodeled area for PADM vs. 1.0 cm² for HADM at 20 weeks. The inherent uniformity of tissue ingrowth and remodeling over time was very different for the HADM relative to the PADM. No differences were observed at the 4-week end point. However, the 20-week data exhibited a statistically different level of variability in the remodeling rate with the mean standard deviation of 0.96 for HADM as contrasted to a mean standard deviation of 2.69 for PADM. This was significant with P < 0.05 using a one tail F test for the inherent variability of the standard deviation. No significant differences between the PADM and HADM for adhesion, inflammation, fibrous tissue or neovascularization were noted.

On the long-term stability of calibration standards in different matrices.

PubMed

Kandić, A; Vukanac, I; Djurašević, M; Novković, D; Šešlak, B; Milošević, Z

2012-09-01

In order to assure Quality Control in accordance with ISO/IEC 17025, it was important, from metrological point of view, to examine the long-term stability of calibration standards previously prepared. Comprehensive reconsideration on efficiency curves with respect to the ageing of calibration standards is presented in this paper. The calibration standards were re-used after a period of 5 years and analysis of the results showed discrepancies in efficiency values. Copyright © 2012 Elsevier Ltd. All rights reserved.

The Arteriovenous (AV) Loop in a Small Animal Model to Study Angiogenesis and Vascularized Tissue Engineering.

PubMed

Weigand, Annika; Beier, Justus P; Arkudas, Andreas; Al-Abboodi, Majida; Polykandriotis, Elias; Horch, Raymund E; Boos, Anja M

2016-11-02

A functional blood vessel network is a prerequisite for the survival and growth of almost all tissues and organs in the human body. Moreover, in pathological situations such as cancer, vascularization plays a leading role in disease progression. Consequently, there is a strong need for a standardized and well-characterized in vivo model in order to elucidate the mechanisms of neovascularization and develop different vascularization approaches for tissue engineering and regenerative medicine. We describe a microsurgical approach for a small animal model for induction of a vascular axis consisting of a vein and artery that are anastomosed to an arteriovenous (AV) loop. The AV loop is transferred to an enclosed implantation chamber to create an isolated microenvironment in vivo, which is connected to the living organism only by means of the vascular axis. Using 3D imaging (MRI, micro-CT) and immunohistology, the growing vasculature can be visualized over time. By implanting different cells, growth factors and matrices, their function in blood vessel network formation can be analyzed without any disturbing influences from the surroundings in a well controllable environment. In addition to angiogenesis and antiangiogenesis studies, the AV loop model is also perfectly suited for engineering vascularized tissues. After a certain prevascularization time, the generated tissues can be transplanted into the defect site and microsurgically connected to the local vessels, thereby ensuring immediate blood supply and integration of the engineered tissue. By varying the matrices, cells, growth factors and chamber architecture, it is possible to generate various tissues, which can then be tailored to the individual patient's needs.

Developmental Gender Differences on the Naglieri Nonverbal Ability Test in a Nationally Normed Sample of 5-17 Year Olds

ERIC Educational Resources Information Center

Rojahn, Johannes; Naglieri, Jack A.

2006-01-01

Lynn [Lynn, R., 2002. Sex differences on the progressive matrices among 15-16 year olds: some data from South Africa. "Personality and Individual Differences 33," 669-673.] proposed that biologically based developmental sex differences produce different IQ trajectories across childhood and adolescence. To test this theory we analyzed the…

A numerical method of detecting singularity

NASA Technical Reports Server (NTRS)

Laporte, M.; Vignes, J.

1978-01-01

A numerical method is reported which determines a value C for the degree of conditioning of a matrix. This value is C = 0 for a singular matrix and has progressively larger values for matrices which are increasingly well-conditioned. This value is C sub = C max sub max (C defined by the precision of the computer) when the matrix is perfectly well conditioned.

IQ Gains in Argentina between 1964 and 1998

ERIC Educational Resources Information Center

Flynn, James R.; Rossi-Case, Lilia

2012-01-01

The literature on IQ gains in Latin America is sparse. We estimate gains on Raven's Progressive Matrices in the city of La Plata (Argentina) between 1964 and 1998. The gains are robust at the top of the curve as well as at the bottom. Therefore, they are contrary to the hypothesis that nutrition played a major role in recent Argentine IQ gains.…

"Culture-Fair" Mental Ability Testing with Schoolchildren: A Review of the Silent Raven; Adequate If Used with Caution.

ERIC Educational Resources Information Center

Sigmon, Scott B.

This paper examines Raven's Colored Progressive Matrices Scale (CPM) IQ test which is considered by many to be "culture fair." The emphasis is on socioeconomic status but factors of sex and ethnicity are also considered. Two major studies from which socioeconomic status data can be extracted are examined. These and other studies found…

Social Inequality and Measurement of Cognition in the Schools: Focusing on Raven's Colored Progressive Matrices Scale.

ERIC Educational Resources Information Center

Sigmon, Scott B.

Social class, as reflected in socioeconomic status (SES), has such a profound influence on all aspects of performance that it is perhaps the most powerful predictor of academic achievement. Intelligence quotient (IQ) tests in one form or another have been used for quantitative assessment of academic ability since Alfred Binet first developed the…

How Does Attention Relate to the Ability-Specific and Position-Specific Components of Reasoning Measured by APM?

ERIC Educational Resources Information Center

Ren, Xuezhu; Goldhammer, Frank; Moosbrugger, Helfried; Schweizer, Karl

2012-01-01

The aim of the present study was to clarify the nature of the ability-specific and position-specific components of Raven's Advanced Progressive Matrices (APM) by relating them to a number of types of attention. The ability-specific component represents the constant part of cognitive performance whereas the position-specific component reflects the…

Some Factors Underlying Mathematical Performance: The Role of Visuospatial Working Memory and Non-Verbal Intelligence

ERIC Educational Resources Information Center

Kyttala, Minna; Lehto, Juhani E.

2008-01-01

Passive and active visuospatial working memory (VSWM) were investigated in relation to maths performance. The mental rotation task was employed as a measure of active VSWM whereas passive VSWM was investigated using a modified Corsi Blocks task and a matrix pattern task. The Raven Progressive Matrices Test measured fluid intelligence. A total of…

Negating Stereotype Threat: Autonomy Support and Academic Identification Boost Performance of African American College Students

ERIC Educational Resources Information Center

Nadler, Dustin R.; Komarraju, Meera

2016-01-01

Using a 2 × 2 factorial design, we examined the effects of stereotype threat and autonomy support on the test performance of 190 African American college students. Participants completed a set of 7 easy and 7 difficult problems from Raven's Progressive Matrices and a survey including measures of Academic Self-Concept, Learning Climate, and…

Progress toward Making Epoxy/Carbon-Nanotube Composites

NASA Technical Reports Server (NTRS)

Tiano, Thomas; Roylance, Margaret; Gassner, John; Kyle, William

2008-01-01

A modicum of progress has been made in an effort to exploit single-walled carbon nanotubes as fibers in epoxy-matrix/fiber composite materials. Two main obstacles to such use of carbon nanotubes are the following: (1) bare nanotubes are not soluble in epoxy resins and so they tend to agglomerate instead of becoming dispersed as desired; and (2) because of lack of affinity between nanotubes and epoxy matrices, there is insufficient transfer of mechanical loads between the nanotubes and the matrices. Part of the effort reported here was oriented toward (1) functionalization of single-walled carbon nanotubes with methyl methacrylate (MMA) to increase their dispersability in epoxy resins and increase transfer of mechanical loads and (2) ultrasonic dispersion of the functionalized nanotubes in tetrahydrofuran, which was used as an auxiliary solvent to aid in dispersing the functionalized nanotubes into a epoxy resin. In another part of this effort, poly(styrene sulfonic acid) was used as the dispersant and water as the auxiliary solvent. In one experiment, the strength of composite of epoxy with MMA-functionalized-nanotubes was found to be 29 percent greater than that of a similar composite of epoxy with the same proportion of untreated nanotubes.

Somatotype and intellectual ability (Raven Progressive Matrices Test) in Chilean school-age children.

PubMed

Tapia, Liliana U; Lizana, Pablo A; Orellana, Yasna Z; Villagrán, Francisca S; Arias, Vanessa F; Almagià, Atilio F; Burrows, Raquel A; Ivanovic, Daniza M

2013-01-01

The aim of this study was to determine the relationship between somatotype and intellectual ability (IA) in 11-12 and 15-16 year-old students (n = 1,015) in the Chile's Metropolitan Region from a representative sample of 33 educational establishments chosen at random. The Heath-Carter somatotype and the IA assessed through the Raven Progressive Matrices Test were measured. The endomorph was observed in 59% of the students; 28% had a mesomorph and 13% ectomorph. The IA was distributed in: 11.2% Grade I, 26.8% Grade II, 41% Grade III, 17.6% Grade IV and 3.2% Grade V. A positive and significant correlation of IA with the endomorphic component (r = 0.074, p = 0.02) was found in the total sample and only in females (r = 0.109, p = 0.02); at the same time, a positive and significant correlation with the ectomorph component was also observed (r = 0.067, p < 0.05). This suggests that other variables would influence more strongly the IA for which further research is needed to quantitate this multifactorial problem. Copyright © AULA MEDICA EDICIONES 2013. Published by AULA MEDICA. All rights reserved.

Spectral Theory of Matrices. I. General Matrices.

DTIC Science & Technology

1980-05-01

bases u 1,...,u m and ,...,v . The rank of A - denoted by r(A) - is defined as the size of the largest minor of A(IA[aOI], a £ Q 0 E Qkn which do not...matrix. Indeed jui is invertible then U" 1 exists in the division ring F. Moreover the standard formula for U " 1 in terms of the minors of U -1...x r minor of A which contains the column b. Since b is a linear combination of the other columns of A we deduce that this minor is a linear

Renormalization-group constraints on Yukawa alignment in multi-Higgs-doublet models

NASA Astrophysics Data System (ADS)

Ferreira, P. M.; Lavoura, L.; Silva, João P.

2010-05-01

We write down the renormalization-group equations for the Yukawa-coupling matrices in a general multi-Higgs-doublet model. We then assume that the matrices of the Yukawa couplings of the various Higgs doublets to right-handed fermions of fixed quantum numbers are all proportional to each other. We demonstrate that, in the case of the two-Higgs-doublet model, this proportionality is preserved by the renormalization-group running only in the cases of the standard type-I, II, X, and Y models. We furthermore show that a similar result holds even when there are more than two Higgs doublets: the Yukawa-coupling matrices to fermions of a given electric charge remain proportional under the renormalization-group running if and only if there is a basis for the Higgs doublets in which all the fermions of a given electric charge couple to only one Higgs doublet.

Storage strategies of eddy-current FE-BI model for GPU implementation

NASA Astrophysics Data System (ADS)

Bardel, Charles; Lei, Naiguang; Udpa, Lalita

2013-01-01

In the past few years graphical processing units (GPUs) have shown tremendous improvements in computational throughput over standard CPU architecture. However, this comes at the cost of restructuring the algorithms to meet the strengths and drawbacks of this GPU architecture. A major drawback is the state of limited memory, and hence storage of FE stiffness matrices on the GPU is important. In contrast to storage on CPU the GPU storage format has significant influence on the overall performance. This paper presents an investigation of a storage strategy in the implementation of a two-dimensional finite element-boundary integral (FE-BI) model for Eddy current NDE applications, on GPU architecture. Specifically, the high dimensional matrices are manipulated by examining the matrix structure and optimally splitting into structurally independent component matrices for efficient storage and retrieval of each component. Results obtained using the proposed approach are compared to those of conventional CPU implementation for validating the method.

Conjugate gradient type methods for linear systems with complex symmetric coefficient matrices

NASA Technical Reports Server (NTRS)

Freund, Roland

1989-01-01

We consider conjugate gradient type methods for the solution of large sparse linear system Ax equals b with complex symmetric coefficient matrices A equals A(T). Such linear systems arise in important applications, such as the numerical solution of the complex Helmholtz equation. Furthermore, most complex non-Hermitian linear systems which occur in practice are actually complex symmetric. We investigate conjugate gradient type iterations which are based on a variant of the nonsymmetric Lanczos algorithm for complex symmetric matrices. We propose a new approach with iterates defined by a quasi-minimal residual property. The resulting algorithm presents several advantages over the standard biconjugate gradient method. We also include some remarks on the obvious approach to general complex linear systems by solving equivalent real linear systems for the real and imaginary parts of x. Finally, numerical experiments for linear systems arising from the complex Helmholtz equation are reported.

Determination and identification of synthetic cannabinoids and their metabolites in different matrices by modern analytical techniques - a review.

PubMed

Znaleziona, Joanna; Ginterová, Pavlína; Petr, Jan; Ondra, Peter; Válka, Ivo; Ševčík, Juraj; Chrastina, Jan; Maier, Vítězslav

2015-05-18

Synthetic cannabinoids have gained popularity due to their easy accessibility and psychoactive effects. Furthermore, they cannot be detected in urine by routine drug monitoring. The wide range of active ingredients in analyzed matrices hinders the development of a standard analytical method for their determination. Moreover, their possible side effects are not well known which increases the danger. This review is focused on the sample preparation and the determination of synthetic cannabinoids in different matrices (serum, urine, herbal blends, oral fluid, hair) published since 2004. The review includes separation and identification techniques, such as thin layer chromatography, gas and liquid chromatography and capillary electrophoresis, mostly coupled with mass spectrometry. The review also includes results by spectral methods like infrared spectroscopy, nuclear magnetic resonance or direct-injection mass spectrometry. Copyright © 2015 Elsevier B.V. All rights reserved.

A Robust Adaptive Unscented Kalman Filter for Nonlinear Estimation with Uncertain Noise Covariance.

PubMed

Zheng, Binqi; Fu, Pengcheng; Li, Baoqing; Yuan, Xiaobing

2018-03-07

The Unscented Kalman filter (UKF) may suffer from performance degradation and even divergence while mismatch between the noise distribution assumed as a priori by users and the actual ones in a real nonlinear system. To resolve this problem, this paper proposes a robust adaptive UKF (RAUKF) to improve the accuracy and robustness of state estimation with uncertain noise covariance. More specifically, at each timestep, a standard UKF will be implemented first to obtain the state estimations using the new acquired measurement data. Then an online fault-detection mechanism is adopted to judge if it is necessary to update current noise covariance. If necessary, innovation-based method and residual-based method are used to calculate the estimations of current noise covariance of process and measurement, respectively. By utilizing a weighting factor, the filter will combine the last noise covariance matrices with the estimations as the new noise covariance matrices. Finally, the state estimations will be corrected according to the new noise covariance matrices and previous state estimations. Compared with the standard UKF and other adaptive UKF algorithms, RAUKF converges faster to the actual noise covariance and thus achieves a better performance in terms of robustness, accuracy, and computation for nonlinear estimation with uncertain noise covariance, which is demonstrated by the simulation results.

A Robust Adaptive Unscented Kalman Filter for Nonlinear Estimation with Uncertain Noise Covariance

PubMed Central

Zheng, Binqi; Yuan, Xiaobing

2018-01-01

The Unscented Kalman filter (UKF) may suffer from performance degradation and even divergence while mismatch between the noise distribution assumed as a priori by users and the actual ones in a real nonlinear system. To resolve this problem, this paper proposes a robust adaptive UKF (RAUKF) to improve the accuracy and robustness of state estimation with uncertain noise covariance. More specifically, at each timestep, a standard UKF will be implemented first to obtain the state estimations using the new acquired measurement data. Then an online fault-detection mechanism is adopted to judge if it is necessary to update current noise covariance. If necessary, innovation-based method and residual-based method are used to calculate the estimations of current noise covariance of process and measurement, respectively. By utilizing a weighting factor, the filter will combine the last noise covariance matrices with the estimations as the new noise covariance matrices. Finally, the state estimations will be corrected according to the new noise covariance matrices and previous state estimations. Compared with the standard UKF and other adaptive UKF algorithms, RAUKF converges faster to the actual noise covariance and thus achieves a better performance in terms of robustness, accuracy, and computation for nonlinear estimation with uncertain noise covariance, which is demonstrated by the simulation results. PMID:29518960

Porting marine ecosystem model spin-up using transport matrices to GPUs

NASA Astrophysics Data System (ADS)

Siewertsen, E.; Piwonski, J.; Slawig, T.

2013-01-01

We have ported an implementation of the spin-up for marine ecosystem models based on transport matrices to graphics processing units (GPUs). The original implementation was designed for distributed-memory architectures and uses the Portable, Extensible Toolkit for Scientific Computation (PETSc) library that is based on the Message Passing Interface (MPI) standard. The spin-up computes a steady seasonal cycle of ecosystem tracers with climatological ocean circulation data as forcing. Since the transport is linear with respect to the tracers, the resulting operator is represented by matrices. Each iteration of the spin-up involves two matrix-vector multiplications and the evaluation of the used biogeochemical model. The original code was written in C and Fortran. On the GPU, we use the Compute Unified Device Architecture (CUDA) standard, a customized version of PETSc and a commercial CUDA Fortran compiler. We describe the extensions to PETSc and the modifications of the original C and Fortran codes that had to be done. Here we make use of freely available libraries for the GPU. We analyze the computational effort of the main parts of the spin-up for two exemplar ecosystem models and compare the overall computational time to those necessary on different CPUs. The results show that a consumer GPU can compete with a significant number of cluster CPUs without further code optimization.

Simultaneous determination of phosphatidylcholine-derived quaternary ammonium compounds by a LC-MS/MS method in human blood plasma, serum and urine samples.

PubMed

Steuer, Christian; Schütz, Philipp; Bernasconi, Luca; Huber, Andreas R

2016-01-01

The determination of circulating trimethylamine-N-oxide (TMAO), choline, betaine, l-carnitine and O-acetyl-l-carnitine concentration in different human matrices is of great clinical interest. Recent results highlighted the prognostic value of TMAO and quaternary ammonium containing metabolites in the field of cardiovascular and kidney diseases. Herein, we report a method for the rapid and simultaneous measurement of closely related phosphatidylcholine-derived metabolites in three different biological matrices by stable isotope dilution assay. Plasma, serum and urine samples were simply deproteinized and separated by HILIC-chromatography. Detection and quantification were performed using LC-MS/MS with electrospray ionization in positive mode. For accuracy and precision, full calibration was performed covering more than the full reference range. Assay performance metrics include intra- and interday imprecision were below 10% for all analytes. To exclude matrix effects standard addition methods were applied for all matrices. It was shown that calibration standards and quality control prepared in water can be used instead of matrix-matched calibration and controls. The LC/MS/MS-based assay described in this article may improve future clinical studies evaluating TMAO and related substances as prognostic markers for cardiovascular risk and all-cause mortality in different patient populations. Copyright © 2015 Elsevier B.V. All rights reserved.

Quantitative radiomics: impact of stochastic effects on textural feature analysis implies the need for standards

PubMed Central

Nyflot, Matthew J.; Yang, Fei; Byrd, Darrin; Bowen, Stephen R.; Sandison, George A.; Kinahan, Paul E.

2015-01-01

Abstract. Image heterogeneity metrics such as textural features are an active area of research for evaluating clinical outcomes with positron emission tomography (PET) imaging and other modalities. However, the effects of stochastic image acquisition noise on these metrics are poorly understood. We performed a simulation study by generating 50 statistically independent PET images of the NEMA IQ phantom with realistic noise and resolution properties. Heterogeneity metrics based on gray-level intensity histograms, co-occurrence matrices, neighborhood difference matrices, and zone size matrices were evaluated within regions of interest surrounding the lesions. The impact of stochastic variability was evaluated with percent difference from the mean of the 50 realizations, coefficient of variation and estimated sample size for clinical trials. Additionally, sensitivity studies were performed to simulate the effects of patient size and image reconstruction method on the quantitative performance of these metrics. Complex trends in variability were revealed as a function of textural feature, lesion size, patient size, and reconstruction parameters. In conclusion, the sensitivity of PET textural features to normal stochastic image variation and imaging parameters can be large and is feature-dependent. Standards are needed to ensure that prospective studies that incorporate textural features are properly designed to measure true effects that may impact clinical outcomes. PMID:26251842

Quantitative radiomics: impact of stochastic effects on textural feature analysis implies the need for standards.

PubMed

Nyflot, Matthew J; Yang, Fei; Byrd, Darrin; Bowen, Stephen R; Sandison, George A; Kinahan, Paul E

2015-10-01

Image heterogeneity metrics such as textural features are an active area of research for evaluating clinical outcomes with positron emission tomography (PET) imaging and other modalities. However, the effects of stochastic image acquisition noise on these metrics are poorly understood. We performed a simulation study by generating 50 statistically independent PET images of the NEMA IQ phantom with realistic noise and resolution properties. Heterogeneity metrics based on gray-level intensity histograms, co-occurrence matrices, neighborhood difference matrices, and zone size matrices were evaluated within regions of interest surrounding the lesions. The impact of stochastic variability was evaluated with percent difference from the mean of the 50 realizations, coefficient of variation and estimated sample size for clinical trials. Additionally, sensitivity studies were performed to simulate the effects of patient size and image reconstruction method on the quantitative performance of these metrics. Complex trends in variability were revealed as a function of textural feature, lesion size, patient size, and reconstruction parameters. In conclusion, the sensitivity of PET textural features to normal stochastic image variation and imaging parameters can be large and is feature-dependent. Standards are needed to ensure that prospective studies that incorporate textural features are properly designed to measure true effects that may impact clinical outcomes.

Prediction of Ras-effector interactions using position energy matrices.

PubMed

Kiel, Christina; Serrano, Luis

2007-09-01

One of the more challenging problems in biology is to determine the cellular protein interaction network. Progress has been made to predict protein-protein interactions based on structural information, assuming that structural similar proteins interact in a similar way. In a previous publication, we have determined a genome-wide Ras-effector interaction network based on homology models, with a high accuracy of predicting binding and non-binding domains. However, for a prediction on a genome-wide scale, homology modelling is a time-consuming process. Therefore, we here successfully developed a faster method using position energy matrices, where based on different Ras-effector X-ray template structures, all amino acids in the effector binding domain are sequentially mutated to all other amino acid residues and the effect on binding energy is calculated. Those pre-calculated matrices can then be used to score for binding any Ras or effector sequences. Based on position energy matrices, the sequences of putative Ras-binding domains can be scanned quickly to calculate an energy sum value. By calibrating energy sum values using quantitative experimental binding data, thresholds can be defined and thus non-binding domains can be excluded quickly. Sequences which have energy sum values above this threshold are considered to be potential binding domains, and could be further analysed using homology modelling. This prediction method could be applied to other protein families sharing conserved interaction types, in order to determine in a fast way large scale cellular protein interaction networks. Thus, it could have an important impact on future in silico structural genomics approaches, in particular with regard to increasing structural proteomics efforts, aiming to determine all possible domain folds and interaction types. All matrices are deposited in the ADAN database (http://adan-embl.ibmc.umh.es/). Supplementary data are available at Bioinformatics online.

A sensitive chemiluminescence enzyme immunoassay based on molecularly imprinted polymers solid-phase extraction of parathion.

PubMed

Chen, Ge; Jin, Maojun; Du, Pengfei; Zhang, Chan; Cui, Xueyan; Zhang, Yudan; She, Yongxin; Shao, Hua; Jin, Fen; Wang, Shanshan; Zheng, Lufei; Wang, Jing

2017-08-01

The chemiluminescence enzyme immunoassay (CLEIA) method responds differently to various sample matrices because of the matrix effect. In this work, the CLEIA method was coupled with molecularly imprinted polymers (MIPs) synthesized by precipitation polymerization to study the matrix effect. The sample recoveries ranged from 72.62% to 121.89%, with a relative standard deviation (RSD) of 3.74-18.14%.The ratio of the sample matrix-matched standard curve slope rate to the solvent standard curve slope was 1.21, 1.12, 1.17, and 0.85 for apple, rice, orange and cabbage in samples pretreated with the mixture of PSA and C 18 . However, the ratio of sample (apple, rice, orange, and cabbage) matrix-matched standard-MIPs curve slope rate to the solvent standard curve was 1.05, 0.92, 1.09, and 1.05 in samples pretreated with MIPs, respectively. The results demonstrated that the matrices of the samples greatly interfered with the detection of parathion residues by CLEIA. The MIPs bound specifically to the parathion in the samples and eliminated the matrix interference effect. Therefore, the CLEIA method have successfully applied MIPs in sample pretreatment to eliminate matrix interference effects and provided a new sensitive assay for agro-products. Copyright © 2017 Elsevier Inc. All rights reserved.

Extracellular matrix collagen alters cell proliferation and cell cycle progression of human uterine leiomyoma smooth muscle cells.

PubMed

Koohestani, Faezeh; Braundmeier, Andrea G; Mahdian, Arash; Seo, Jane; Bi, JiaJia; Nowak, Romana A

2013-01-01

Uterine leiomyomas (ULs) are benign tumors occurring in the majority of reproductive aged women. Despite the high prevalence of these tumors, little is known about their etiology. A hallmark of ULs is the excessive deposition of extracellular matrix (ECM), primarily collagens. Collagens are known to modulate cell behavior and function singularly or through interactions with integrins and growth factor-mediated mitogenic pathways. To better understand the pathogenesis of ULs and the role of ECM collagens in their growth, we investigated the interaction of leiomyoma smooth muscle cells (LSMCs) with two different forms of collagen, non-polymerized collagen (monomeric) and polymerized collagen (fibrillar), in the absence or presence of platelet-derived growth factor (PDGF), an abundant growth factor in ULs. Primary cultures of human LSMCS from symptomatic patients were grown on these two different collagen matrices and their morphology, cytoskeletal organization, cellular proliferation, and signaling pathways were evaluated. Our results showed that LSMCs had distinct morphologies on the different collagen matrices and their basal as well as PDGF-stimulated proliferation varied on these matrices. These differences in proliferation were accompanied by changes in cell cycle progression and p21, an inhibitory cell cycle protein. In addition we found alterations in the phosphorylation of focal adhesion kinase, cytoskeletal reorganization, and activation of the mitogen activated protein kinase (MAPK) signaling pathway. In conclusion, our results demonstrate a direct effect of ECM on the proliferation of LSMCs through interplay between the collagen matrix and the PDGF-stimulated MAPK pathway. In addition, these findings will pave the way for identifying novel therapeutic approaches for ULs that target ECM proteins and their signaling pathways in ULs.

Extracellular Matrix Collagen Alters Cell Proliferation and Cell Cycle Progression of Human Uterine Leiomyoma Smooth Muscle Cells

PubMed Central

Koohestani, Faezeh; Braundmeier, Andrea G.; Mahdian, Arash; Seo, Jane; Bi, JiaJia; Nowak, Romana A.

2013-01-01

Uterine leiomyomas (ULs) are benign tumors occurring in the majority of reproductive aged women. Despite the high prevalence of these tumors, little is known about their etiology. A hallmark of ULs is the excessive deposition of extracellular matrix (ECM), primarily collagens. Collagens are known to modulate cell behavior and function singularly or through interactions with integrins and growth factor-mediated mitogenic pathways. To better understand the pathogenesis of ULs and the role of ECM collagens in their growth, we investigated the interaction of leiomyoma smooth muscle cells (LSMCs) with two different forms of collagen, non-polymerized collagen (monomeric) and polymerized collagen (fibrillar), in the absence or presence of platelet-derived growth factor (PDGF), an abundant growth factor in ULs. Primary cultures of human LSMCS from symptomatic patients were grown on these two different collagen matrices and their morphology, cytoskeletal organization, cellular proliferation, and signaling pathways were evaluated. Our results showed that LSMCs had distinct morphologies on the different collagen matrices and their basal as well as PDGF-stimulated proliferation varied on these matrices. These differences in proliferation were accompanied by changes in cell cycle progression and p21, an inhibitory cell cycle protein. In addition we found alterations in the phosphorylation of focal adhesion kinase, cytoskeletal reorganization, and activation of the mitogen activated protein kinase (MAPK) signaling pathway. In conclusion, our results demonstrate a direct effect of ECM on the proliferation of LSMCs through interplay between the collagen matrix and the PDGF-stimulated MAPK pathway. In addition, these findings will pave the way for identifying novel therapeutic approaches for ULs that target ECM proteins and their signaling pathways in ULs. PMID:24040420

Measuring intellectual ability in cerebral palsy: The comparison of three tests and their neuroimaging correlates.

PubMed

Ballester-Plané, Júlia; Laporta-Hoyos, Olga; Macaya, Alfons; Póo, Pilar; Meléndez-Plumed, Mar; Vázquez, Élida; Delgado, Ignacio; Zubiaurre-Elorza, Leire; Narberhaus, Ana; Toro-Tamargo, Esther; Russi, Maria Eugenia; Tenorio, Violeta; Segarra, Dolors; Pueyo, Roser

2016-09-01

Standard intelligence scales require both verbal and manipulative responses, making it difficult to use in cerebral palsy and leading to underestimate their actual performance. This study aims to compare three intelligence tests suitable for the heterogeneity of cerebral palsy in order to identify which one(s) could be more appropriate to use. Forty-four subjects with bilateral dyskinetic cerebral palsy (26 male, mean age 23 years) conducted the Raven's Coloured Progressive Matrices (RCPM), the Peabody Picture Vocabulary Test-3rd (PPVT-III) and the Wechsler Nonverbal Scale of Ability (WNV). Furthermore, a comprehensive neuropsychological battery and magnetic resonance imaging were assessed. The results show that PPVT-III gives limited information on cognitive performance and brain correlates, getting lower intelligence quotient scores. The WNV provides similar outcomes as RCPM, but cases with severe motor impairment were unable to perform it. Finally, the RCPM gives more comprehensive information on cognitive performance, comprising not only visual but also verbal functions. It is also sensitive to the structural state of the brain, being related to basal ganglia, thalamus and white matter areas such as superior longitudinal fasciculus. So, the RCPM may be considered a standardized easy-to-administer tool with great potential in both clinical and research fields of bilateral cerebral palsy. Copyright © 2016 Elsevier Ltd. All rights reserved.

Validated method for quantification of genetically modified organisms in samples of maize flour.

PubMed

Kunert, Renate; Gach, Johannes S; Vorauer-Uhl, Karola; Engel, Edwin; Katinger, Hermann

2006-02-08

Sensitive and accurate testing for trace amounts of biotechnology-derived DNA from plant material is the prerequisite for detection of 1% or 0.5% genetically modified ingredients in food products or raw materials thereof. Compared to ELISA detection of expressed proteins, real-time PCR (RT-PCR) amplification has easier sample preparation and detection limits are lower. Of the different methods of DNA preparation CTAB method with high flexibility in starting material and generation of sufficient DNA with relevant quality was chosen. Previous RT-PCR data generated with the SYBR green detection method showed that the method is highly sensitive to sample matrices and genomic DNA content influencing the interpretation of results. Therefore, this paper describes a real-time DNA quantification based on the TaqMan probe method, indicating high accuracy and sensitivity with detection limits of lower than 18 copies per sample applicable and comparable to highly purified plasmid standards as well as complex matrices of genomic DNA samples. The results were evaluated with ValiData for homology of variance, linearity, accuracy of the standard curve, and standard deviation.

The MCCB impairment profile for schizophrenia outpatients: results from the MATRICS psychometric and standardization study.

PubMed

Kern, Robert S; Gold, James M; Dickinson, Dwight; Green, Michael F; Nuechterlein, Keith H; Baade, Lyle E; Keefe, Richard S E; Mesholam-Gately, Raquelle I; Seidman, Larry J; Lee, Cathy; Sugar, Catherine A; Marder, Stephen R

2011-03-01

The MATRICS Psychometric and Standardization Study was conducted as a final stage in the development of the MATRICS Consensus Cognitive Battery (MCCB). The study included 176 persons with schizophrenia or schizoaffective disorder and 300 community residents. Data were analyzed to examine the cognitive profile of clinically stable schizophrenia patients on the MCCB. Secondarily, the data were analyzed to identify which combination of cognitive domains and corresponding cut-off scores best discriminated patients from community residents, and patients competitively employed vs. those not. Raw scores on the ten MCCB tests were entered into the MCCB scoring program which provided age- and gender-corrected T-scores on seven cognitive domains. To test for between-group differences, we conducted a 2 (group)×7 (cognitive domain) MANOVA with follow-up independent t-tests on the individual domains. Classification and regression trees (CART) were used for the discrimination analyses. Examination of patient T-scores across the seven cognitive domains revealed a relatively compact profile with T-scores ranging from 33.4 for speed of processing to 39.3 for reasoning and problem-solving. Speed of processing and social cognition best distinguished individuals with schizophrenia from community residents; speed of processing along with visual learning and attention/vigilance optimally distinguished patients competitively employed from those who were not. The cognitive profile findings provide a standard to which future studies can compare results from other schizophrenia samples and related disorders; the classification results point to specific areas and levels of cognitive impairment that may advance work rehabilitation efforts. Published by Elsevier B.V.

The MCCB Impairment Profile for Schizophrenia Outpatients:Results from the MATRICS Psychometric and Standardization Study

PubMed Central

Kern, Robert S.; Gold, James M.; Dickinson, Dwight; Green, Michael F.; Nuechterlein, Keith H.; Baade, Lyle E.; Keefe, Richard S. E.; Mesholam-Gately, Raquelle I.; Seidman, Larry J.; Lee, Cathy; Sugar, Catherine A.; Marder, Stephen R.

2010-01-01

The MATRICS Psychometric and Standardization Study was conducted as a final stage in the development of the MATRICS Consensus Cognitive Battery (MCCB). The study included 176 persons with schizophrenia or schizoaffective disorder and 300 community residents. Data were analyzed to examine the cognitive profile of clinically stable schizophrenia patients on the MCCB. Secondarily, the data were analyzed to identify which combination of cognitive domains and corresponding cut-off scores best discriminated patients from community residents, and patients competitively employed vs. those not. Raw scores on the ten MCCB tests were entered into the MCCB scoring program which provided age-and gender-corrected T-scores on seven cognitive domains. To test for between-group differences, we conducted a 2 (group) × 7 (cognitive domain) MANOVA with follow-up independent t – tests on the individual domains. Classification and regression trees (CART) were used for the discrimination analyses. Examination of patient T-scores across the seven cognitive domains revealed a relatively compact profile with T-scores ranging from 33.4 for speed of processing to 39.3 for reasoning and problem-solving. Speed of processing and social cognition best distinguished individuals with schizophrenia from community residents; speed of processing along with visual learning and attention/vigilance optimally distinguished patients competitively employed from those who were not. The cognitive profile findings provide a standard to which future studies can compare results from other schizophrenia samples and related disorders; the classification results point to specific areas and levels of cognitive impairment that may advance work rehabilitation efforts. PMID:21159492

Collection of Pyrethroids in Water and Sediment Matrices: Development and Validation of a Standard Operating Procedure

USGS Publications Warehouse

Hladik, Michelle; Orlando, James L.; Kuivila, Kathryn

2009-01-01

Loss of pyrethroid insecticides onto surfaces during sample collection can confound the interpretation of analytical and toxicity test results. Sample collection devices, container materials, and water matrix composition have a significant influence on the association of pyrethroids to container walls, which can be as high as 50 percent. Any sample collection method involving transfer through multiple containers or pieces of equipment increases the potential for pyrethroid loss. This loose 'surface-association' with container walls can be reversed through agitation. When sampling water matrices with pumps or autosamplers, no pyrethroids were lost as long as the water was moving continuously through the system. When collecting water matrices in containers, the material with the least amount of pyrethroid sorption is as follows: glass less than (<) plastic less than (<) Teflon. Additionally, pyrethroids were easier to re-suspend from the glass container walls. Since the amount of surface-association is proportional to the ratio of volume-to-contact-area of the sample, taking larger-volume field samples (greater than 3 liters) reduced pyrethroid losses to less than 10 percent. The amount of surface-association cannot be predicted easily because of the dependence on water matrix composition; samples with higher dissolved organic carbon or suspended-sediment concentrations were observed to have lower percent loss. Sediment samples were not affected by glass-container sorption (the only containers tested). Standardized sample-collection protocols are critical to yield accurate pyrethroid concentrations for assessment of potential effects, and have been summarized in an accompanying standard operating procedure.

Simultaneous determination of three pesticide adjuvant residues in plant-derived agro-products using liquid chromatography-tandem mass spectrometry.

PubMed

Li, Hui; Jiang, Zejun; Cao, Xiaolin; Su, Hang; Shao, Hua; Jin, Fen; Abd El-Aty, A M; Wang, Jing

2017-12-15

Herein, an accurate and reliable isotope-labelled internal standard method was developed and validated for simultaneous determination of three polar pesticide adjuvants, namely 2-pyrrolidone, N-methyl-2-pyrrolidone, and N-ethyl-2-pyrrolidone in plant-derived agro-products. Matrices, including apple, cabbage, tomato, cucumber, rice, and wheat were extracted with a modified quick, easy, cheap, effective, rugged, and safe "QuEChERS" method and purified with a new clean-up sorbent (Z-Sep). A hydrophilic interaction liquid chromatography column (HILIC), exhibiting a lipophilic-hydrophilic character, was used to separate the three analytes over 10min using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Matrix effects in various matrices were evaluated and an isotope-labelled internal standard method was employed to compensate for ion enhancement/suppression effects. At three fortification levels (2.0, 5.0, and 20.0μg/kg), the mean recoveries ranged from 78.5 to 112.1% with relative standard deviations (RSDs)<11.0% for all tested analytes. The limits of detection (LODs) and quantification (LOQs) were 0.04-0.45 and 0.12-1.58μg/kg in various matrices, respectively. The developed experimental protocol was successfully applied to monitor different samples purchased from local markets in Beijing, China. In conclusion, the developed method exhibited both high sensitivity and satisfactory accuracy and is suitable for the simultaneous determination of the three tested pesticide adjuvant residues in agro-products of plant origin. Copyright © 2017 Elsevier B.V. All rights reserved.

Validation of reliable and selective methods for direct determination of glyphosate and aminomethylphosphonic acid in milk and urine using LC-MS/MS.

PubMed

Jensen, Pamela K; Wujcik, Chad E; McGuire, Michelle K; McGuire, Mark A

2016-01-01

Simple high-throughput procedures were developed for the direct analysis of glyphosate [N-(phosphonomethyl)glycine] and aminomethylphosphonic acid (AMPA) in human and bovine milk and human urine matrices. Samples were extracted with an acidified aqueous solution on a high-speed shaker. Stable isotope labeled internal standards were added with the extraction solvent to ensure accurate tracking and quantitation. An additional cleanup procedure using partitioning with methylene chloride was required for milk matrices to minimize the presence of matrix components that can impact the longevity of the analytical column. Both analytes were analyzed directly, without derivatization, by liquid chromatography tandem mass spectrometry using two separate precursor-to-product transitions that ensure and confirm the accuracy of the measured results. Method performance was evaluated during validation through a series of assessments that included linearity, accuracy, precision, selectivity, ionization effects and carryover. Limits of quantitation (LOQ) were determined to be 0.1 and 10 µg/L (ppb) for urine and milk, respectively, for both glyphosate and AMPA. Mean recoveries for all matrices were within 89-107% at three separate fortification levels including the LOQ. Precision for replicates was ≤ 7.4% relative standard deviation (RSD) for milk and ≤ 11.4% RSD for urine across all fortification levels. All human and bovine milk samples used for selectivity and ionization effects assessments were free of any detectable levels of glyphosate and AMPA. Some of the human urine samples contained trace levels of glyphosate and AMPA, which were background subtracted for accuracy assessments. Ionization effects testing showed no significant biases from the matrix. A successful independent external validation was conducted using the more complicated milk matrices to demonstrate method transferability.

Effects of Training in Problem Solving on the Problem-Solving Abilities of Gifted Fourth Graders: A Comparison of the Future Problem Solving and Instrumental Enrichment Programs.

ERIC Educational Resources Information Center

Dufner, Hillrey A.; Alexander, Patricia A.

The differential effects of two different types of problem-solving training on the problem-solving abilities of gifted fourth graders were studied. Two successive classes of gifted fourth graders from Weslaco Independent School District (Texas) were pretested with the Coloured Progressive Matrices (CPM) and Thinking Creatively With Pictures…

Differences in Achievement Motivation and Academic and Social Self-Concept in Gifted Students of Higher Education

ERIC Educational Resources Information Center

Sierra, María Dolores Valadez; Cuervo, Angel Alberto Valdés; Amezaga, Teodoro Rafael Wendlandt; Sánchez, Ana Carolina Reyes; Guzmán, Rogelio Zambrano; Agraz, Juan Pedro Navarro

2015-01-01

The purpose of this study is to identify groups of gifted university students that differ in their self-concept and achievement motivation. For this, 80 students who achieved scores of the 95th percentile or higher in the Raven's Progressive Matrices test were selected. Two groups were identified in terms of their social self-concept and the…

New Strategies in Targeted Interventions for Posttraumatic Osteoarthritis (PT-OA)

DTIC Science & Technology

2016-08-01

changes No changes Fisher, M., Sonokawa, M., Conroy, S., Shepard , J., Dealy, N. Reducing EGFR signal activity slows progression of post-traumatic...Quantification for Stem Cell Based Tissue Engineered Cartilage, Stem Cell and Regenerative Medicine, Sept, 2013, University of Illinois at Chicago ...UIC), Chicago , IL. 18. Nukavarapu, S.P.* Tissue Engineered Matrices for Large Area Bone Regeneration, Gordon Research Conference on Musculoskeletal

The Average IQ of Sub-Saharan Africans: Comments on Wicherts, Dolan, and van der Maas

ERIC Educational Resources Information Center

Lynn, Richard; Meisenberg, Gerhard

2010-01-01

Wicherts, Dolan, and van der Maas (2009) contend that the average IQ of sub-Saharan Africans is about 80. A critical evaluation of the studies presented by WDM shows that many of these are based on unrepresentative elite samples. We show that studies of 29 acceptably representative samples on tests other than the Progressive Matrices give a…

DIMETHYLTHIOARSINIC ANHYDRIDE: A STANDARD FOR ARSENIC SPECIATION

EPA Science Inventory

Dimethylthioarsinic acid (DMTAV) has recently been identified in biological, dietary and environmental matrices. The relevance of this compound to the toxicity of arsenic in humans is unknown and further exposure assessment and metabolic studies are difficult to conduct because ...

Loop-Mediated Isothermal Amplification for Salmonella Detection in Food and Feed: Current Applications and Future Directions

PubMed Central

Yang, Qianru; Domesle, Kelly J.

2018-01-01

Abstract Loop-mediated isothermal amplification (LAMP) has become a powerful alternative to polymerase chain reaction (PCR) for pathogen detection in clinical specimens and food matrices. Nontyphoidal Salmonella is a zoonotic pathogen of significant food and feed safety concern worldwide. The first study employing LAMP for the rapid detection of Salmonella was reported in 2005, 5 years after the invention of the LAMP technology in Japan. This review provides an overview of international efforts in the past decade on the development and application of Salmonella LAMP assays in a wide array of food and feed matrices. Recent progress in assay design, platform development, commercial application, and method validation is reviewed. Future perspectives toward more practical and wider applications of Salmonella LAMP assays in food and feed testing are discussed. PMID:29902082

Conventional and alternative matrices for driving under the influence of cannabis: recent progress and remaining challenges.

PubMed

Wille, Sarah M R; Ramírez-Fernandez, Maria Del Mar; Samyn, Nele; De Boeck, Gert

2010-04-01

In the past decade much research concerning the impact of cannabis use on road safety has been conducted. More specifically, studies on effects of cannabis smoking on driving performance, as well as epidemiological studies and cannabis-detection techniques have been published. As a result, several countries have adopted driving under the influence of drugs (DUID) legislations, with varying approaches worldwide. A wide variety of bodily fluids have been utilized to determine the presence of cannabis. Urine and blood are the most widely used matrices for DUID legislations. However, more and more publications focus on the usability of oral fluid testing for this purpose. Each matrix provides different information about time and extent of use and likelihood of impairment. This review will focus on the practical aspects of implying a DUID legislation. The pros and cons of the different biological matrices used for Δ(9)-tetrahydrocannabinol screening and quantification will be discussed. In addition, a literature overview concerning (roadside) cannabinoid detection, as well as laboratory confirmation techniques is given. Finally, we will discuss important issues influencing interpretation of these data, such as oral fluid collection, choice of cut-offs, stability and proficiency testing.

A European network for food-borne parasites (Euro-FBP): meeting report on 'Analytical methods for food-borne parasites in human and veterinary diagnostics and in food matrices'.

PubMed

Klotz, Christian; Šoba, Barbara; Skvarč, Miha; Gabriël, Sarah; Robertson, Lucy J

2017-11-09

Food-borne parasites (FBPs) are a neglected topic in food safety, partly due to a lack of awareness of their importance for public health, especially as symptoms tend not to develop immediately after exposure. In addition, methodological difficulties with both diagnosis in infected patients and detection in food matrices result in under-detection and therefore the potential for underestimation of their burden on our societies. This, in consequence, leads to lower prioritization for basic research, e.g. for development new and more advanced detection methods for different food matrices and diagnostic samples, and thus a vicious circle of neglect and lack of progress is propagated. The COST Action FA1408, A European Network for Foodborne Parasites (Euro-FBP) aims to combat the impact of FBP on public health by facilitating the multidisciplinary cooperation and partnership between groups of researchers and between researchers and stakeholders. The COST Action TD1302, the European Network for cysticercosis/taeniosis, CYSTINET, has a specific focus on Taenia solium and T. saginata, two neglected FBPs, and aims to advance knowledge and understanding of these zoonotic disease complexes via collaborations in a multidisciplinary scientific network. This report summarizes the results of a meeting within the Euro-FBP consortium entitled 'Analytical methods for food-borne parasites in human and veterinary diagnostics and in food matrices' and of the joined Euro-FBP and CYSTINET meeting.

Immobilization of radioactive and hazardous wastes in a developed sulfur polymer cement (SPC) matrix

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wagdy, M.; Azim, Abdel; El-Gammal, Belal

Available in abstract form only. Full text of publication follows: A process has been developed for the immobilization Cs, Sr, Ce, Pb, and Cr in forms that is non-dispersible and could be safely immobilized. The simulated radioactive wastes of Cs, Sr, and Ce, and the hazardous wastes of Cr, and Pb were immobilized in the stable form of sulfur polymer cement (SPC). In this process, the contaminants (in a single form) were added to the sulfur mixture of sulfur and aromatic /or aliphatic hydrocarbons that used as polymerizing agents for sulfur (95% S, and 5% organic polymer by weight). Durabilitymore » of the fabricated SPC matrices was assessed in terms of their water of immersion, porosity, and compressive strength. The water immersion, and open porosity were found to be less than 2.5% for all the prepared matrices, whereas the compressive strength was in the range between 62.4 and 142.3 Kg.cm{sup -2}, depending on the composition of the prepared matrix. The prepared SPC matrices that characterized by X-ray diffraction (XRD) showed that the different added contaminants were stabilized during the solidification process during their reaction with sulfur and the organic polymer to form the corresponding metal sulfides. Toxicity Characteristic Leaching Procedure (TCLP), and the IAEA standard method have assessed the leachability of the prepared waste matrices. The TCLP results showed that most the concentration of the contaminants released were under their detection limit. The leach index for the investigated metals from the prepared SPC matrices was in the range of 9-11. The order of release of the investigated metals was Sr>Cs>Pb>Cr>Ce for the aliphatic polymer, and Sr>Cr>Pb>Cs>Ce for the aromatic one. The results obtained revealed a high performance for the prepared SPC matrices, as they are of low cost effect, highly available materials, and possessed good mechanical and leaching properties. Key Words: SPC/ Matrices/ Immobilization/ Wastes/ Leachability. (authors)« less

The origin of mass

NASA Astrophysics Data System (ADS)

Froggatt*, C. D.

2003-01-01

The quark-lepton mass problem and the ideas of mass protection are reviewed. The hierarchy problem and suggestions for its resolution, including Little Higgs models, are discussed. The Multiple Point Principle (MPP) is introduced and used within the Standard Model (SM) to predict the top quark and Higgs particle masses. Mass matrix ansätze are considered; in particular we discuss the lightest family mass generation model, in which all the quark mixing angles are successfully expressed in terms of simple expressions involving quark mass ratios. It is argued that an underlying chiral flavour symmetry is responsible for the hierarchical texture of the fermion mass matrices. The phenomenology of neutrino mass matrices is briefly discussed.

Six steps to an effective denials management program.

PubMed

Robertson, Brian; Doré, Alexander

2005-09-01

The following six steps can help you manage denials management issues in your organization: Create standard definitions of denial types. Establish a denial hierarchy. Establish a centralized denial database. Develop key performance indicators. Build responsibility matrices. Measure, monitor, and take action.

Occurrence and quantification of Shiga toxin-producing Escherichia coli from food matrices

PubMed Central

Sethulekshmi, C.; Latha, C.; Anu, C. J.

2018-01-01

Aim: The objective of the study was to detect Shiga toxin-producing Escherichia coli (STEC) and develop a quantitative polymerase chain reaction (qPCR) assay to quantify the bacterial DNA present in different food matrices. Materials and Methods: A total of 758 samples were collected during a period from January 2015 to December 2016 from Kozhikode, Thrissur, and Alappuzha districts of Kerala. The samples consisted of raw milk (135), pasteurized milk (100), beef (132), buffalo meat (130), chevon (104), beef kheema (115), and beef sausage (42). All the samples collected were subjected to isolation and identification of STEC by conventional culture technique. Confirmation of virulence genes was carried out using PCR. For the quantification of STEC in different food matrices, a qPCR was standardized against stx1 gene of STEC by the construction of standard curve using SYBR green chemistry. Results: The overall occurrence of STEC in raw milk (n=135), beef (n=132), buffalo meat (n=130), chevon (n=104), and beef kheema (n=115) samples collected from Kozhikode, Thrissur, and Alappuzha districts of Kerala was 19.26%, 41.6%, 16.92%, 28.85%, and 41.74%, respectively. PCR revealed the presence of stx 1 and stx 2 genes in 88.46 and 83.64 and 30.77 and 40.00% of STEC isolates from raw milk and beef samples, respectively, while 100% of the STEC isolates from buffalo beef and beef kheema samples carried stx 1 gene. Real-time qPCR assay was used to quantify the bacterial cells present in different food matrices. The standard curve was developed, and the slopes, intercept, and R2 of linear regression curves were −3.10, 34.24, and 0.99, respectively. Conclusion: The considerably high occurrence of STEC in the study confirms the importance of foods of animal origin as a vehicle of infection to humans. In the present study, on comparing the overall occurrence of STEC, the highest percentage of occurrence was reported in beef kheema samples. The study shows the need for rigid food safety measures to combat the potential pathogenic effects of harmful bacteria throughout the production chain from production to consumption. PMID:29657388

The Average IQ of Sub-Saharan Africans Assessed by the Progressive Matrices: A Reply to Wicherts, Dolan, Carlson & van der Maas

ERIC Educational Resources Information Center

Lynn, Richard

2010-01-01

Wicherts, Dolan, Carlson & van der Maas (WDCM) (2010) contend that the average IQ in sub-Saharan Africa is about 76 in relation to a British mean of 100 and sd of 15. This result is achieved by including many studies of unrepresentative elite samples. Studies of acceptably representative samples indicate a sub-Saharan Africa IQ of…

Distinct neural substrates of visuospatial and verbal-analytic reasoning as assessed by Raven's Advanced Progressive Matrices.

PubMed

Chen, Zhencai; De Beuckelaer, Alain; Wang, Xu; Liu, Jia

2017-11-24

Recent studies revealed spontaneous neural activity to be associated with fluid intelligence (gF) which is commonly assessed by Raven's Advanced Progressive Matrices, and embeds two types of reasoning: visuospatial and verbal-analytic reasoning. With resting-state fMRI data, using global brain connectivity (GBC) analysis which averages functional connectivity of a voxel in relation to all other voxels in the brain, distinct neural correlates of these two reasoning types were found. For visuospatial reasoning, negative correlations were observed in both the primary visual cortex (PVC) and the precuneus, and positive correlations were observed in the temporal lobe. For verbal-analytic reasoning, negative correlations were observed in the right inferior frontal gyrus (rIFG), dorsal anterior cingulate cortex and temporoparietal junction, and positive correlations were observed in the angular gyrus. Furthermore, an interaction between GBC value and type of reasoning was found in the PVC, rIFG and the temporal lobe. These findings suggest that visuospatial reasoning benefits more from elaborate perception to stimulus features, whereas verbal-analytic reasoning benefits more from feature integration and hypothesis testing. In sum, the present study offers, for different types of reasoning in gF, first empirical evidence of separate neural substrates in the resting brain.

Exploring visuospatial abilities and their contribution to constructional abilities and nonverbal intelligence.

PubMed

Trojano, Luigi; Siciliano, Mattia; Cristinzio, Chiara; Grossi, Dario

2018-01-01

The present study aimed at exploring relationships among the visuospatial tasks included in the Battery for Visuospatial Abilities (BVA), and at assessing the relative contribution of different facets of visuospatial processing on tests tapping constructional abilities and nonverbal abstract reasoning. One hundred forty-four healthy subjects with a normal score on Mini Mental State Examination completed the BVA plus Raven's Coloured Progressive Matrices and Constructional Apraxia test. We used Principal Axis Factoring and Parallel Analysis to investigate relationships among the BVA visuospatial tasks, and performed regression analyses to assess the visuospatial contribution to constructional abilities and nonverbal abstract reasoning. Principal Axis Factoring and Parallel Analysis revealed two eigenvalues exceeding 1, accounting for about 60% of the variance. A 2-factor model provided the best fit. Factor 1 included sub-tests exploring "complex" visuospatial skills, whereas Factor 2 included two subtests tapping "simple" visuospatial skills. Regression analyses revealed that both Factor 1 and Factor 2 significantly affected performance on Raven's Coloured Progressive Matrices, whereas only the Factor 1 affected performance on Constructional Apraxia test. Our results supported functional segregation proposed by De Renzi, suggesting clinical caution to utilize a single test to assess visuospatial domain, and qualified the visuospatial contribution in drawing and non-verbal intelligence test.

Maillard-reaction-induced modification and aggregation of proteins and hardening of texture in protein bar model systems.

PubMed

Zhou, Peng; Guo, Mufan; Liu, Dasong; Liu, Xiaoming; Labuza, Teodore P

2013-03-01

The hardening of high-protein bars causes problems in their acceptability to consumers. The objective of this study was to determine the progress of the Maillard reaction in model systems of high-protein nutritional bars containing reducing sugars, and to illustrate the influences of the Maillard reaction on the modification and aggregation of proteins and the hardening of bar matrices during storage. The progress of the Maillard reaction, glycation, and aggregation of proteins, and textural changes in bar matrices were investigated during storage at 25, 35, and 45 °C. The initial development of the Maillard reaction caused little changes in hardness; however, further storage resulted in dramatic modification of protein with formation of high-molecular-weight polymers, resulting in the hardening in texture. The replacement of reducing sugars with nonreducing ingredients such as sugar alcohols in the formula minimized the changes in texture. The hardening of high-protein bars causes problems in their acceptability to consumers. Maillard reaction is one of the mechanisms contributing to the hardening of bar matrix, particularly for the late stage of storage. The replacement of reducing sugars with nonreducing ingredients such as sugar alcohols in the formula will minimize the changes in texture. © 2013 Institute of Food Technologists®

Identification and Quantification of N-Acyl Homoserine Lactones Involved in Bacterial Communication by Small-Scale Synthesis of Internal Standards and Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry.

PubMed

Leipert, Jan; Treitz, Christian; Leippe, Matthias; Tholey, Andreas

2017-12-01

N-acyl homoserine lactones (AHL) are small signal molecules involved in the quorum sensing of many gram-negative bacteria, and play an important role in biofilm formation and pathogenesis. Present analytical methods for identification and quantification of AHL require time-consuming sample preparation steps and are hampered by the lack of appropriate standards. By aiming at a fast and straightforward method for AHL analytics, we investigated the applicability of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Suitable MALDI matrices, including crystalline and ionic liquid matrices, were tested and the fragmentation of different AHL in collision-induced dissociation MS/MS was studied, providing information about characteristic marker fragments ions. Employing small-scale synthesis protocols, we established a versatile and cost-efficient procedure for fast generation of isotope-labeled AHL standards, which can be used without extensive purification and yielded accurate standard curves. Quantitative analysis was possible in the low pico-molar range, with lower limits of quantification reaching from 1 to 5 pmol for different AHL. The developed methodology was successfully applied in a quantitative MALDI MS analysis of low-volume culture supernatants of Pseudomonas aeruginosa. Graphical abstract ᅟ.

Simultaneous determination of chlorantraniliprole and cyantraniliprole in fruits, vegetables and cereals using ultra-high-performance liquid chromatography-tandem mass spectrometry with the isotope-labelled internal standard method.

PubMed

Pan, Xinglu; Dong, Fengshou; Xu, Jun; Liu, Xingang; Chen, Zenglong; Liu, Na; Chen, Xixi; Tao, Yan; Zhang, Hongjun; Zheng, Yongquan

2015-05-01

A reliable and sensitive isotope-labelled internal standard method for simultaneous determination of chlorantraniliprole and cyantraniliprole in fruits (apple and grape), vegetables (cucumber and tomato) and cereals (rice and wheat) using ultra-high-performance liquid chromatography-tandem mass spectrometry was developed. Isotope-labelled internal standards were effective in compensating for the loss in the pretreatment and overcoming the matrix effect. The analytes were extracted with acetonitrile and cleaned up with different kinds of sorbents. The determination of the target compounds was achieved in less than 4 min using a T3 column combined with an electrospray ionization source in positive mode. The overall average relative recoveries in all matrices at three spiking levels (10, 20 and 50 μg kg(-1)) ranged from 95.5 to 106.2 %, with all relative standard deviations being less than 14.4 % for all analytes. The limits of detection did not exceed 0.085 μg kg(-1) and the limits of quantification were below 0.28 μg kg(-1) in all matrices. The method was demonstrated to be convenient and accurate for the routine monitoring of chlorantraniliprole and cyantraniliprole in fruits, vegetables and cereals.

Identification and Quantification of N-Acyl Homoserine Lactones Involved in Bacterial Communication by Small-Scale Synthesis of Internal Standards and Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry

NASA Astrophysics Data System (ADS)

Leipert, Jan; Treitz, Christian; Leippe, Matthias; Tholey, Andreas

2017-12-01

N-acyl homoserine lactones (AHL) are small signal molecules involved in the quorum sensing of many gram-negative bacteria, and play an important role in biofilm formation and pathogenesis. Present analytical methods for identification and quantification of AHL require time-consuming sample preparation steps and are hampered by the lack of appropriate standards. By aiming at a fast and straightforward method for AHL analytics, we investigated the applicability of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Suitable MALDI matrices, including crystalline and ionic liquid matrices, were tested and the fragmentation of different AHL in collision-induced dissociation MS/MS was studied, providing information about characteristic marker fragments ions. Employing small-scale synthesis protocols, we established a versatile and cost-efficient procedure for fast generation of isotope-labeled AHL standards, which can be used without extensive purification and yielded accurate standard curves. Quantitative analysis was possible in the low pico-molar range, with lower limits of quantification reaching from 1 to 5 pmol for different AHL. The developed methodology was successfully applied in a quantitative MALDI MS analysis of low-volume culture supernatants of Pseudomonas aeruginosa. [Figure not available: see fulltext.

Standardized Methods to Generate Mock (Spiked) Clinical Specimens by Spiking Blood or Plasma with Cultured Pathogens

PubMed Central

Dong, Ming; Fisher, Carolyn; Añez, Germán; Rios, Maria; Nakhasi, Hira L.; Hobson, J. Peyton; Beanan, Maureen; Hockman, Donna; Grigorenko, Elena; Duncan, Robert

2016-01-01

Aims To demonstrate standardized methods for spiking pathogens into human matrices for evaluation and comparison among diagnostic platforms. Methods and Results This study presents detailed methods for spiking bacteria or protozoan parasites into whole blood and virus into plasma. Proper methods must start with a documented, reproducible pathogen source followed by steps that include standardized culture, preparation of cryopreserved aliquots, quantification of the aliquots by molecular methods, production of sufficient numbers of individual specimens and testing of the platform with multiple mock specimens. Results are presented following the described procedures that showed acceptable reproducibility comparing in-house real-time PCR assays to a commercially available multiplex molecular assay. Conclusions A step by step procedure has been described that can be followed by assay developers who are targeting low prevalence pathogens. Significance and Impact of Study The development of diagnostic platforms for detection of low prevalence pathogens such as biothreat or emerging agents is challenged by the lack of clinical specimens for performance evaluation. This deficit can be overcome using mock clinical specimens made by spiking cultured pathogens into human matrices. To facilitate evaluation and comparison among platforms, standardized methods must be followed in the preparation and application of spiked specimens. PMID:26835651

Visualizing Matrix Multiplication

ERIC Educational Resources Information Center

Daugulis, Peteris; Sondore, Anita

2018-01-01

Efficient visualizations of computational algorithms are important tools for students, educators, and researchers. In this article, we point out an innovative visualization technique for matrix multiplication. This method differs from the standard, formal approach by using block matrices to make computations more visual. We find this method a…

USEPA MANUAL OF METHODS FOR VIROLOGY

EPA Science Inventory

This chapter describes procedures for the detection of coliphases in water matrices. These procedures are based on those presented in the Supplement to the 20th Edition of Standard Methods for the Examination of Water and Eastewater and EPA Methods 1601 and 1602. Two quantitati...

Decellularized Tissue and Cell-Derived Extracellular Matrices as Scaffolds for Orthopaedic Tissue Engineering

PubMed Central

Cheng, Christina W.; Solorio, Loran D.; Alsberg, Eben

2014-01-01

The reconstruction of musculoskeletal defects is a constant challenge for orthopaedic surgeons. Musculoskeletal injuries such as fractures, chondral lesions, infections and tumor debulking can often lead to large tissue voids requiring reconstruction with tissue grafts. Autografts are currently the gold standard in orthopaedic tissue reconstruction; however, there is a limit to the amount of tissue that can be harvested before compromising the donor site. Tissue engineering strategies using allogeneic or xenogeneic decellularized bone, cartilage, skeletal muscle, tendon and ligament have emerged as promising potential alternative treatment. The extracellular matrix provides a natural scaffold for cell attachment, proliferation and differentiation. Decellularization of in vitro cell-derived matrices can also enable the generation of autologous constructs from tissue specific cells or progenitor cells. Although decellularized bone tissue is widely used clinically in orthopaedic applications, the exciting potential of decellularized cartilage, skeletal muscle, tendon and ligament cell-derived matrices has only recently begun to be explored for ultimate translation to the orthopaedic clinic. PMID:24417915

Towards topological quantum computer

NASA Astrophysics Data System (ADS)

Melnikov, D.; Mironov, A.; Mironov, S.; Morozov, A.; Morozov, An.

2018-01-01

Quantum R-matrices, the entangling deformations of non-entangling (classical) permutations, provide a distinguished basis in the space of unitary evolutions and, consequently, a natural choice for a minimal set of basic operations (universal gates) for quantum computation. Yet they play a special role in group theory, integrable systems and modern theory of non-perturbative calculations in quantum field and string theory. Despite recent developments in those fields the idea of topological quantum computing and use of R-matrices, in particular, practically reduce to reinterpretation of standard sets of quantum gates, and subsequently algorithms, in terms of available topological ones. In this paper we summarize a modern view on quantum R-matrix calculus and propose to look at the R-matrices acting in the space of irreducible representations, which are unitary for the real-valued couplings in Chern-Simons theory, as the fundamental set of universal gates for topological quantum computer. Such an approach calls for a more thorough investigation of the relation between topological invariants of knots and quantum algorithms.

An O(N squared) method for computing the eigensystem of N by N symmetric tridiagonal matrices by the divide and conquer approach

NASA Technical Reports Server (NTRS)

Gill, Doron; Tadmor, Eitan

1988-01-01

An efficient method is proposed to solve the eigenproblem of N by N Symmetric Tridiagonal (ST) matrices. Unlike the standard eigensolvers which necessitate O(N cubed) operations to compute the eigenvectors of such ST matrices, the proposed method computes both the eigenvalues and eigenvectors with only O(N squared) operations. The method is based on serial implementation of the recently introduced Divide and Conquer (DC) algorithm. It exploits the fact that by O(N squared) of DC operations, one can compute the eigenvalues of N by N ST matrix and a finite number of pairs of successive rows of its eigenvector matrix. The rest of the eigenvectors--all of them or one at a time--are computed by linear three-term recurrence relations. Numerical examples are presented which demonstrate the superiority of the proposed method by saving an order of magnitude in execution time at the expense of sacrificing a few orders of accuracy.

Liver regenerative medicine: advances and challenges.

PubMed

Chistiakov, Dimitry A

2012-01-01

Liver transplantation is the standard care for many end-stage liver diseases. However, donor organs are scarce and some people succumb to liver failure before a donor is found. Liver regenerative medicine is a special interdisciplinary field of medicine focused on the development of new therapies incorporating stem cells, gene therapy and engineered tissues in order to repair or replace the damaged organ. In this review we consider the emerging progress achieved in the hepatic regenerative medicine within the last decade. The review starts with the characterization of liver organogenesis, fetal and adult stem/progenitor cells. Then, applications of primary hepatocytes, embryonic and adult (mesenchymal, hematopoietic and induced pluripotent) stem cells in cell therapy of liver diseases are considered. Current advances and challenges in producing mature hepatocytes from stem/progenitor cells are discussed. A section about hepatic tissue engineering includes consideration of synthetic and natural biomaterials in engineering scaffolds, strategies and achievements in the development of 3D bioactive matrices and 3D hepatocyte cultures, liver microengineering, generating bioartificial liver and prospects for fabrication of the bioengineered liver. Copyright © 2012 S. Karger AG, Basel.

Progress in bacterial cellulose matrices for biotechnological applications.

PubMed

Cacicedo, Maximiliano L; Castro, M Cristina; Servetas, Ioannis; Bosnea, Loulouda; Boura, Konstantina; Tsafrakidou, Panagiota; Dima, Agapi; Terpou, Antonia; Koutinas, Athanasios; Castro, Guillermo R

2016-08-01

Bacterial cellulose (BC) is an extracellular polymer produced by many microorganisms. The Komagataeibacter genus is the best producer using semi-synthetic media and agricultural wastes. The main advantages of BC are the nanoporous structure, high water content and free hydroxyl groups. Modification of BC can be made by two strategies: in-situ, during the BC production, and ex-situ after BC purification. In bioprocesses, multilayer BC nanocomposites can contain biocatalysts designed to be suitable for outside to inside cell activities. These nanocomposites biocatalysts can (i) increase productivity in bioreactors and bioprocessing, (ii) provide cell activities does not possess without DNA cloning and (iii) provide novel nano-carriers for cell inside activity and bioprocessing. In nanomedicine, BC matrices containing therapeutic molecules can be used for pathologies like skin burns, and implantable therapeutic devices. In nanoelectronics, semiconductors BC-based using salts and synthetic polymers brings novel films showing excellent optical and photochemical properties. Copyright © 2016 Elsevier Ltd. All rights reserved.

Novel ionic liquid matrices for qualitative and quantitative detection of carbohydrates by matrix assisted laser desorption/ionization mass spectrometry.

PubMed

Zhao, Xiaoyong; Shen, Shanshan; Wu, Datong; Cai, Pengfei; Pan, Yuanjiang

2017-09-08

Analysis of carbohydrates based on matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is still challenging and researchers have been devoting themselves to efficient matrices discovery. In the present study, the design, synthesis, qualitative and quantitative performance of non-derivative ionic liquid matrices (ILMs) were reported. DHB/N-methylaniline (N-MA) and DHB/N-ethylaniline (N-EA), performing best for carbohydrate detection, have been screened out. The limit of detection for oligosaccharide provided by DHB/N-MA and DHB/N-EA were as low as 10 fmol. DHB/N-MA and DHB/N-EA showed significantly higher ion generation efficiency than DHB. The comparison of capacity to probe polysaccharide between these two ILMs and DHB also revealed their powerful potential. Their outstanding performance were probably due to lower proton affinities and stronger UV absorption at λ = 355 nm. What is more, taking DHB/N-MA as an example, quantitative analysis of fructo-oligosaccharide mixtures extracted and identified from rice noodles has been accomplished sensitively using an internal standard method. Overall, DHB/N-MA and DHB/N-EA exhibited excellent performance and might be significant sources as the carbohydrate matrices. Copyright © 2017 Elsevier B.V. All rights reserved.

Determination of phenol compounds in surface water matrices by bar adsorptive microextraction-high performance liquid chromatography-diode array detection.

PubMed

Neng, Nuno R; Nogueira, José M F

2014-07-03

Bar adsorptive microextraction combined with liquid desorption followed by high performance liquid chromatography with diode array detection (BAµE-LD/HPLC-DAD) is proposed for the determination of trace levels of five phenol compounds (3-nitrophenol, 4-nitrophenol, bisphenol-A, 4-n-octylphenol and 4-n-nonylphenol) in surface water matrices. By using a polystyrene-divinylbenzene copolymer (PS-DVB) sorbent phase, high selectivity and efficiency is achieved even against polydimethylsiloxane through stir bar sorptive extraction. Assays performed by BAµE(PS-DVB)-LD/HPLC-DAD on 25 mL water samples spiked at the 10.0 µg/L levels yielded recoveries over 88.0%±5.7% for all five analytes, under optimized experimental conditions. The analytical performance showed good precision (RSD<15%), detection limits of 0.25 µg/L and linear dynamic ranges (1.0-25.0 μg/L) with determination coefficient higher than 0.9904. By using the standard addition method, the application of the present method to surface water matrices allowed very good performances at the trace level. The proposed methodology proved to be a suitable alternative to monitor phenol compounds in surface water matrices, showing to be easy to implement, reliable, sensitive and requiring a low sample volume.

MICROWAVE-ASSISTED EXTRACTION OF ORGANIC COMPOUNDS FROM STANDARD REFERENCE SOILS AND SEDIMENTS

EPA Science Inventory

As part of an ongoing evaluation of new sample preparation techniques by the U.S. Environmental Protection Agency (EPA), especially those that minimize waste solvents, microwave-assisted extraction (MAE) of organic compounds from solid materials (or "matrices") was evaluated. Six...

Isotope dilution liquid chromatography - mass spectrometry methods for fat- and water-soluble vitamins in nutritional formulations.

PubMed

Phinney, Karen W; Rimmer, Catherine A; Thomas, Jeanice Brown; Sander, Lane C; Sharpless, Katherine E; Wise, Stephen A

2011-01-01

Vitamins are essential to human health, and dietary supplements containing vitamins are widely used by individuals hoping to ensure they have adequate intake of these important nutrients. Measurement of vitamins in nutritional formulations is necessary to monitor regulatory compliance and in studies examining the nutrient intake of specific populations. Liquid chromatographic methods, primarily with UV absorbance detection, are well established for both fat- and water-soluble measurements, but they do have limitations for certain analytes and may suffer from a lack of specificity in complex matrices. Liquid chromatography-mass spectrometry (LC-MS) provides both sensitivity and specificity for the determination of vitamins in these matrices, and simultaneous analysis of multiple vitamins in a single analysis is often possible. In this work, LC-MS methods were developed for both fat- and water-soluble vitamins and applied to the measurement of these analytes in two NIST Standard Reference Materials. When possible, stable isotope labeled internal standards were employed for quantification.

Parameter expansion for estimation of reduced rank covariance matrices (Open Access publication)

PubMed Central

Meyer, Karin

2008-01-01

Parameter expanded and standard expectation maximisation algorithms are described for reduced rank estimation of covariance matrices by restricted maximum likelihood, fitting the leading principal components only. Convergence behaviour of these algorithms is examined for several examples and contrasted to that of the average information algorithm, and implications for practical analyses are discussed. It is shown that expectation maximisation type algorithms are readily adapted to reduced rank estimation and converge reliably. However, as is well known for the full rank case, the convergence is linear and thus slow. Hence, these algorithms are most useful in combination with the quadratically convergent average information algorithm, in particular in the initial stages of an iterative solution scheme. PMID:18096112

Determination of silicon in biological and botanical reference materials by epithermal INAA and Compton suppression

NASA Astrophysics Data System (ADS)

Landsberger, S.; Peshev, S.; Becker, D. A.

1994-12-01

Silicon determination in sixteen botanical and biological standard reference materials is described using the 29Si(n, p) 29Al reaction through instrumental epithermal neutron activation analysis and Compton suppression gamma-ray spectroscopy. By simultaneous utilization of both cadmium and boron epithermal filters along with anticoincidence gamma-counting, detection limits as low as 12 ppm were obtained for certain matrices, much lower than previously reported values for this type of analysis. The method is applicable to many botanical and biological matrices and is attractive with its interference free, purely instrumental nature, compared with methods using the 28Si(n, p) 28Al reaction or chemical separation techniques.

Hydrogen-atom tunneling through a very high barrier; spontaneous thiol → thione conversion in thiourea isolated in low-temperature Ar, Ne, H2 and D2 matrices.

PubMed

Rostkowska, Hanna; Lapinski, Leszek; Nowak, Maciej J

2018-05-23

Spontaneous thiol → thione hydrogen-atom transfer has been investigated for molecules of thiourea trapped in Ar, Ne, normal-H2 (n-H2) and normal-D2 (n-D2) low-temperature matrices. The most stable thione isomer was the only form of the compound present in the matrices after their deposition. According to MP2/6-311++G(2d,p) calculations, the thiol tautomer should be higher in energy by 62.5 kJ mol-1. This less stable thiol form of the compound was photochemically generated in a thione → thiol process, occurring upon UV irradiation of the matrix. Subsequently, a very slow spontaneous conversion of the thiol tautomer into the thione form was observed for the molecules isolated in Ar, Ne, n-H2 and n-D2 matrices kept at 3.5 K and in the dark. Since the thiol → thione transformation in thiourea is a process involving the dissociation of a chemical bond, the barrier for this hydrogen-atom transfer is very high (104-181 kJ mol-1). Crossing such a high potential-energy barrier at a temperature as low as 3.5 K, is possible only by hydrogen-atom tunneling. The experimentally measured time constants of this tunneling process: 52 h (Ar), 76 h (Ne), 94 h (n-H2) and 94 h (n-D2), do not differ much from one another. Hence, the dependence of the tunneling rate on the matrix environment is not drastic. The progress of the thiol → thione conversion was also monitored for Ar matrices at different temperature: 3.5 K, 9 K and 15 K. For this temperature range, the experiments revealed no detectable temperature dependence of the rate of the tunneling process.

On Dynamics of Spinning Structures

NASA Technical Reports Server (NTRS)

Gupta, K. K.; Ibrahim, A.

2012-01-01

This paper provides details of developments pertaining to vibration analysis of gyroscopic systems, that involves a finite element structural discretization followed by the solution of the resulting matrix eigenvalue problem by a progressive, accelerated simultaneous iteration technique. Thus Coriolis, centrifugal and geometrical stiffness matrices are derived for shell and line elements, followed by the eigensolution details as well as solution of representative problems that demonstrates the efficacy of the currently developed numerical procedures and tools.

Birth order, family size, and intelligence.

PubMed

Belmont, L; Marolla, F A

1973-12-14

The relation of birth order and family size to intellectual performance, as measured by the Raven Progressive Matrices, was examined among nearly all of 400,000 19-year-old males born in the Netherlands in 1944 through 1947. It was found that birth order and family size had independent effects on intellectual performance. Effects of family size were not present in all social classes, but effects of birth order were consistent across social class.

EFFECTS OF A HEAVY-ATOM SALT ON THE SOLID-MATRIX LUMINESCENCE PROPERTIES OF TRANS-7,8-DIHYDROXY-ANTI-9,10-EPOXY-7,8,9,10-TETRAHYDROBENZO[A]PYRENE-DNA ADDUCTS AND TETROL I-1 ADSORBED ON SEVERAL SOLID MATRICES. (R824100)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

Progress Report of the IAU Working Group on Precession and the Ecliptic

DTIC Science & Technology

2006-12-01

may be used with either the traditional rotation matrix, or those rotation matrices described in Capitaine et al. (2003) and Fukushima (2003). We...precession of about 6.4 mas cent−2 in longitude. Thus, the precession theory was not dynamically consistent. 93 Furthermore, Fukushima (2003) showed that...2003, Capitaine et al. 2003, and Fukushima 2003) have been published recently to address the shortcomings of the precession portion, including the

Photoresponse of polyaniline-functionalized graphene quantum dots

NASA Astrophysics Data System (ADS)

Lai, Sin Ki; Luk, Chi Man; Tang, Libin; Teng, Kar Seng; Lau, Shu Ping

2015-03-01

Polyaniline-functionalized graphene quantum dots (PANI-GQD) and pristine graphene quantum dots (GQDs) were utilized for optoelectronic devices. The PANI-GQD based photodetector exhibited higher responsivity which is about an order of magnitude at 405 nm and 7 folds at 532 nm as compared to GQD-based photodetectors. The improved photoresponse is attributed to the enhanced interconnection of GQD by island-like polymer matrices, which facilitate carrier transport within the polymer matrices. The optically tunable current-voltage (I-V) hysteresis of PANI-GQD was also demonstrated. The hysteresis magnifies progressively with light intensity at a scan range of +/-1 V. Both GQD and PANI-GQD devices change from positive to negative photocurrent when the bias reaches 4 V. Photogenerated carriers are excited to the trapping states in GQDs with increased bias. The trapped charges interact with charges injected from the electrodes which results in a net decrease of free charge carriers and a negative photocurrent. The photocurrent switching phenomenon in GQD and PANI-GQD devices may open up novel applications in optoelectronics.Polyaniline-functionalized graphene quantum dots (PANI-GQD) and pristine graphene quantum dots (GQDs) were utilized for optoelectronic devices. The PANI-GQD based photodetector exhibited higher responsivity which is about an order of magnitude at 405 nm and 7 folds at 532 nm as compared to GQD-based photodetectors. The improved photoresponse is attributed to the enhanced interconnection of GQD by island-like polymer matrices, which facilitate carrier transport within the polymer matrices. The optically tunable current-voltage (I-V) hysteresis of PANI-GQD was also demonstrated. The hysteresis magnifies progressively with light intensity at a scan range of +/-1 V. Both GQD and PANI-GQD devices change from positive to negative photocurrent when the bias reaches 4 V. Photogenerated carriers are excited to the trapping states in GQDs with increased bias. The trapped charges interact with charges injected from the electrodes which results in a net decrease of free charge carriers and a negative photocurrent. The photocurrent switching phenomenon in GQD and PANI-GQD devices may open up novel applications in optoelectronics. Electronic supplementary information (ESI) available: Raman spectrum of PANI-GQD, TGA, Red-shift of PL peak with the amounts of aniline, excitation dependent PL of PANI-GQD, area of hysteretic loop for different voltage scan ranges, photocurrent at 1 V under prolonged illumination. See DOI: 10.1039/c4nr07565j

A sensitive LC-MS/MS method for measurement of organophosphorus pesticides and their oxygen analogs in air sampling matrices

PubMed Central

ARMSTRONG, JENNA L.; DILLS, RUSSELL L.; YU, JIANBO; YOST, MICHAEL G.; FENSKE, RICHARD A.

2018-01-01

A rapid liquid chromatography tandem mass spectrometry (LC-MS/MS) method has been developed for determination of levels of the organophosphorus (OP) pesticides chlorpyrifos (CPF), azinphos methyl (AZM), and their oxygen analogs chlorpyrifos-oxon (CPF-O) and azinphos methyl-oxon (AZM-O) on common active air sampling matrices. XAD-2 resin and polyurethane foam (PUF) matrices were extracted with acetonitrile containing stable-isotope labeled internal standards (ISTD). Analysis was accomplished in Multiple Reaction Monitoring (MRM) mode, and analytes in unknown samples were identified by retention time (±0.1 min) and qualifier ratio (±30% absolute) as compared to the mean of calibrants. For all compounds, calibration linearity correlation coefficients were ≥0.996. Limits of detection (LOD) ranged from 0.15–1.1 ng/sample for CPF, CPF-O, AZM, and AZM-O on active sampling matrices. Spiked fortification recoveries were 78–113% from XAD-2 active air sampling tubes and 71–108% from PUF active air sampling tubes. Storage stability tests also yielded recoveries ranging from 74–94% after time periods ranging from 2–10 months. The results demonstrate that LC-MS/MS is a sensitive method for determining these compounds from two different matrices at the low concentrations that can result from spray drift and long range transport in non-target areas following agricultural applications. In an inter-laboratory comparison, the limit of quantification (LOQ) for LC-MS/MS was 100 times lower than a typical gas chromatography-mass spectrometry (GC-MS) method. PMID:24328542

A sensitive LC-MS/MS method for measurement of organophosphorus pesticides and their oxygen analogs in air sampling matrices.

PubMed

Armstrong, Jenna L; Dills, Russell L; Yu, Jianbo; Yost, Michael G; Fenske, Richard A

2014-01-01

A rapid liquid chromatography tandem mass spectrometry (LC-MS/MS) method has been developed for determination of levels of the organophosphorus (OP) pesticides chlorpyrifos (CPF), azinphos methyl (AZM), and their oxygen analogs chlorpyrifos-oxon (CPF-O) and azinphos methyl-oxon (AZM-O) on common active air sampling matrices. XAD-2 resin and polyurethane foam (PUF) matrices were extracted with acetonitrile containing stable-isotope labeled internal standards (ISTD). Analysis was accomplished in Multiple Reaction Monitoring (MRM) mode, and analytes in unknown samples were identified by retention time (±0.1 min) and qualifier ratio (±30% absolute) as compared to the mean of calibrants. For all compounds, calibration linearity correlation coefficients were ≥0.996. Limits of detection (LOD) ranged from 0.15-1.1 ng/sample for CPF, CPF-O, AZM, and AZM-O on active sampling matrices. Spiked fortification recoveries were 78-113% from XAD-2 active air sampling tubes and 71-108% from PUF active air sampling tubes. Storage stability tests also yielded recoveries ranging from 74-94% after time periods ranging from 2-10 months. The results demonstrate that LC-MS/MS is a sensitive method for determining these compounds from two different matrices at the low concentrations that can result from spray drift and long range transport in non-target areas following agricultural applications. In an inter-laboratory comparison, the limit of quantification (LOQ) for LC-MS/MS was 100 times lower than a typical gas chromatography-mass spectrometry (GC-MS) method.

Sports drug testing using complementary matrices: Advantages and limitations.

PubMed

Thevis, Mario; Geyer, Hans; Tretzel, Laura; Schänzer, Wilhelm

2016-10-25

Today, routine doping controls largely rely on testing whole blood, serum, and urine samples. These matrices allow comprehensively covering inorganic as well as low and high molecular mass organic analytes relevant to doping controls and are collecting and transferring from sampling sites to accredited anti-doping laboratories under standardized conditions. Various aspects including time and cost-effectiveness as well as intrusiveness and invasiveness of the sampling procedure but also analyte stability and breadth of the contained information have been motivation to consider and assess values potentially provided and added to modern sports drug testing programs by alternative matrices. Such alternatives could be dried blood spots (DBS), dried plasma spots (DPS), oral fluid (OF), exhaled breath (EB), and hair. In this review, recent developments and test methods concerning these alternative matrices and expected or proven contributions as well as limitations of these specimens in the context of the international anti-doping fight are presented and discussed, guided by current regulations for prohibited substances and methods of doping as established by the World Anti-Doping Agency (WADA). Focusing on literature published between 2011 and 2015, examples for doping control analytical assays concerning non-approved substances, anabolic agents, peptide hormones/growth factors/related substances and mimetics, β 2 -agonists, hormone and metabolic modulators, diuretics and masking agents, stimulants, narcotics, cannabinoids, glucocorticoids, and beta-blockers were selected to outline the advantages and limitations of the aforementioned alternative matrices as compared to conventional doping control samples (i.e. urine and blood/serum). Copyright © 2016 Elsevier B.V. All rights reserved.

AOAC SMPR 2015.009: Estimation of total phenolic content using Folin-C Assay

USDA-ARS?s Scientific Manuscript database

This AOAC Standard Method Performance Requirements (SMPR) is for estimation of total soluble phenolic content in dietary supplement raw materials and finished products using the Folin-C assay for comparison within same matrices. SMPRs describe the minimum recommended performance characteristics to b...

Tumor cell invasion of collagen matrices requires coordinate lipid agonist-induced G-protein and membrane-type matrix metalloproteinase-1-dependent signaling.

PubMed

Fisher, Kevin E; Pop, Andreia; Koh, Wonshill; Anthis, Nicholas J; Saunders, W Brian; Davis, George E

2006-12-08

Lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P) are bioactive lipid signaling molecules implicated in tumor dissemination. Membrane-type matrix metalloproteinase 1 (MT1-MMP) is a membrane-tethered collagenase thought to be involved in tumor invasion via extracellular matrix degradation. In this study, we investigated the molecular requirements for LPA- and S1P-regulated tumor cell migration in two dimensions (2D) and invasion of three-dimensional (3D) collagen matrices and, in particular, evaluated the role of MT1-MMP in this process. LPA stimulated while S1P inhibited migration of most tumor lines in Boyden chamber assays. Conversely, HT1080 fibrosarcoma cells migrated in response to both lipids. HT1080 cells also markedly invaded 3D collagen matrices (approximatly 700 microm over 48 hours) in response to either lipid. siRNA targeting of LPA1 and Rac1, or S1P1, Rac1, and Cdc42 specifically inhibited LPA- or S1P-induced HT1080 invasion, respectively. Analysis of LPA-induced HT1080 motility on 2D substrates vs. 3D matrices revealed that synthetic MMP inhibitors markedly reduced the distance (approximately 125 microm vs. approximately 45 microm) and velocity of invasion (approximately 0.09 microm/min vs. approximately 0.03 microm/min) only when cells navigated 3D matrices signifying a role for MMPs exclusively in invasion. Additionally, tissue inhibitors of metalloproteinases (TIMPs)-2, -3, and -4, but not TIMP-1, blocked lipid agonist-induced invasion indicating a role for membrane-type (MT)-MMPs. Furthermore, MT1-MMP expression in several tumor lines directly correlated with LPA-induced invasion. HEK293s, which neither express MT1-MMP nor invade in the presence of LPA, were transfected with MT1-MMP cDNA, and subsequently invaded in response to LPA. When HT1080 cells were seeded on top of or within collagen matrices, siRNA targeting of MT1-MMP, but not other MMPs, inhibited lipid agonist-induced invasion establishing a requisite role for MT1-MMP in this process. LPA is a fundamental regulator of MT1-MMP-dependent tumor cell invasion of 3D collagen matrices. In contrast, S1P appears to act as an inhibitory stimulus in most cases, while stimulating only select tumor lines. MT1-MMP is required only when tumor cells navigate 3D barriers and not when cells migrate on 2D substrata. We demonstrate that tumor cells require coordinate regulation of LPA/S1P receptors and Rho GTPases to migrate, and additionally, require MT1-MMP in order to invade collagen matrices during neoplastic progression.

Salmonella detection in poultry samples. Comparison of two commercial real-time PCR systems with culture methods for the detection of Salmonella spp. in environmental and fecal samples of poultry.

PubMed

Sommer, D; Enderlein, D; Antakli, A; Schönenbrücher, H; Slaghuis, J; Redmann, T; Lierz, M

2012-01-01

The efficiency of two commercial PCR methods based on real-time technology, the foodproof® Salmonella detection system and the BAX® PCR Assay Salmonella system was compared to standardized culture methods (EN ISO 6579:2002 - Annex D) for the detection of Salmonella spp. in poultry samples. Four sample matrices (feed, dust, boot swabs, feces) obtained directly from poultry flocks, as well as artificially spiked samples of the same matrices, were used. All samples were tested for Salmonella spp. using culture methods first as the gold standard. In addition samples spiked with Salmonella Enteridis were tested to evaluate the sensitivity of both PCR methods. Furthermore all methods were evaluated in an annual ring-trial of the National Salmonella Reference Laboratory of Germany. Salmonella detection in the matrices feed, dust and boot swabs were comparable in both PCR systems whereas the results from feces differed markedly. The quality, especially the freshness, of the fecal samples had an influence on the sensitivity of the real-time PCR and the results of the culture methods. In fresh fecal samples an initial spiking level of 100cfu/25g Salmonella Enteritidis was detected. Two-days-dried fecal samples allowed the detection of 14cfu/25g. Both real- time PCR protocols appear to be suitable for the detection of Salmonella spp. in all four matrices. The foodproof® system detected eight samples more to be positive compared to the BAX® system, but had a potential false positive result in one case. In 7-days-dried samples none of the methods was able to detect Salmonella likely through letal cell damage. In general the advantage of PCR analyses over the culture method is the reduction of working time from 4-5 days to only 2 days. However, especially for the analysis of fecal samples official validation should be conducted according to the requirement of EN ISO6579:2002 - Annex D.

Quantitative on-line analysis of sulfur compounds in complex hydrocarbon matrices.

PubMed

Djokic, Marko R; Ristic, Nenad D; Olahova, Natalia; Marin, Guy B; Van Geem, Kevin M

2017-08-04

An improved method for on-line measurement of sulfur containing compounds in complex matrices is presented. The on-line system consists of a specifically designed sampling system connected to a comprehensive two-dimensional gas chromatograph (GC×GC) equipped with two capillary columns (Rtx ® -1 PONA×SGE BPX50), a flame ionization detector (FID) and a sulfur chemiluminescence detector (SCD). The result is an unprecedented sensitivity down to ppm level (1 ppm-w) for various sulfur containing compounds in very complex hydrocarbon matrices. In addition to the GC×GC-SCD, the low molecular weight sulfur containing compounds such as hydrogen sulfide (H 2 S) and carbonyl sulfide (COS) can be analyzed using a thermal conductivity detector of a so-called refinery gas analyzer (RGA). The methodology was extensively tested on a continuous flow pilot plant for steam cracking, in which quantification of sulfur containing compounds in the reactor effluent was carried out using 3-chlorothiophene as internal standard. The GC×GC-FID/-SCD settings were optimized for ppm analysis of sulfur compounds in olefin-rich (ethylene- and propylene-rich) hydrocarbon matrices produced by steam cracking of petroleum feedstocks. Besides that is primarily used for analysis of the hydrocarbon matrix, FID of the GC×GC-FID/-SCD set-up serves to double check the amount of added sulfur internal standard which is crucial for a proper quantification of sulfur compounds. When vacuum gas oil containing 780 ppm-w of elemental sulfur in the form of benzothiophenes and dibenzothiophenes is subjected to steam cracking, the sulfur balance was closed, with 75% of the sulfur contained in the feed is converted to hydrogen sulfide, 13% to alkyl homologues of thiophene while the remaining 12% is present in the form of alkyl homologues of benzothiophenes. The methodology can be applied for many other conversion processes which use sulfur containing feeds such as hydrocracking, catalytic cracking, kerogen evolution, bio-waste pyrolysis, supercritical water treatment, etc. Copyright © 2017 Elsevier B.V. All rights reserved.

Simultaneous determination and identity confirmation of thiodicarb and its degradation product methomyl in animal-derived foodstuffs using high-performance liquid chromatography with fluorescence detection and tandem mass spectrometry.

PubMed

Rahman, Md Musfiqur; Abd El-Aty, A M; Kim, Sung-Woo; Lee, Young-Jun; Na, Tae-Woong; Park, Joon-Seong; Shin, Ho-Chul; Shim, Jae-Han

2017-01-01

A high-performance liquid chromatography-fluorescence detection method was developed for the simultaneous determination of thiodicarb and its degradation product methomyl in animal-derived food products, including chicken muscle, beef, pork, table eggs, and milk. Thiodicarb is known to degrade during analysis; therefore, a thorough investigation was carried out, revealing that thiodicarb degrades to methomyl immediately after spiking into a matrix of animal-derived food products. Consequently, thiodicarb was determined as the sum of the parent compound and methomyl. Samples were extracted with acetonitrile and sodium salts, and purified using solid-phase extraction (SPE). The limits of detection (LODs) and quantification (LOQs) were 0.0013 and 0.004mg/kg, respectively, for both analytes in various matrices. Seven-point external calibration curves were obtained, and they showed excellent linearity with determination coefficients (R 2 )≥0.999 for all tested matrices. The method was validated at three fortification levels (LOQ, LOQ×2, and LOQ×10) in triplicate with average recoveries ranging from 84.24 to 112.8% (for methomyl) and relative standard deviations (RSDs)≤6.5% in all matrices. The converted recoveries of thiodicarb in various matrices ranged from 74.80 to 107.80% with RSDs≤4.5%. The identities of both compounds in standard solutions and for recovery were confirmed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The developed method was further validated by accurate reproduction at another laboratory. Finally, the method was applied to market samples collected from different areas (and, in the case of milk, different brands), and none of the samples tested positive for thiodicarb or methomyl. In conclusion, the developed method can be successfully applied for a single-run analysis of thiodicarb and methomyl in livestock products. Copyright © 2016 Elsevier B.V. All rights reserved.

METHOD FOR THE DETERMINATION OF PERCHLORATE ANION IN PLANT AND SOLID MATRICES BY ION CHROMATOGRAPHY

EPA Science Inventory

A standardized method for the analysis of perchlorate in plants was developed, based on dry weight, and applied to the analysis of plant organs, foodstuffs, and plant products. The procedure greatly reduced the ionic interferences in water extracts of plant materials. Ion chro...

A Geometrical Framework for Covariance Matrices of Continuous and Categorical Variables

ERIC Educational Resources Information Center

Vernizzi, Graziano; Nakai, Miki

2015-01-01

It is well known that a categorical random variable can be represented geometrically by a simplex. Accordingly, several measures of association between categorical variables have been proposed and discussed in the literature. Moreover, the standard definitions of covariance and correlation coefficient for continuous random variables have been…

Direct separation of boron from Na- and Ca-rich matrices by sublimation for stable isotope measurement by MC-ICP-MS.

PubMed

Wang, Bo-Shian; You, Chen-Feng; Huang, Kuo-Fang; Wu, Shein-Fu; Aggarwal, Suresh Kumar; Chung, Chuan-Hsiung; Lin, Pei-Ying

2010-09-15

An improved technique for precise and accurate determination of boron isotopic composition in Na-rich natural waters (groundwater, seawater) and marine biogenic carbonates was developed. This study used a 'micro-sublimation' technique to separate B from natural sample matrices in place of the conventional ion-exchange extraction. By adjusting analyte to appropriate pH, quantitative recovery of boron can be achieved (>98%) and the B procedural blank is limited to <8 pg. An additional mass bias effect in MC-ICP-MS was observed which could not be improved via the standard-sample-standard bracketing or the 'pseudo internal' normalization by Li. Therefore a standard other than NBS SRM 951 was used to monitor plasma condition in order to maintain analytical accuracy. An isotope cross-calibration with results from TIMS shows that the space-charge mass bias on MC-ICP-MS can be successfully corrected using off-line mathematical manipulation. Several reference materials, including the seawater IAPSO and two groundwater standards IAEA-B-2 and IAEA-B-3, were used to validate this approach. We found that the delta(11)B of the reference coral JCp-1 was 24.22+/-0.28 per thousand, corresponding to seawater pH based on the coral delta(11)B-pH function. Copyright (c) 2010 Elsevier B.V. All rights reserved.

A new look at the simultaneous analysis and design of structures

NASA Technical Reports Server (NTRS)

Striz, Alfred G.

1994-01-01

The minimum weight optimization of structural systems, subject to strength and displacement constraints as well as size side constraints, was investigated by the Simultaneous ANalysis and Design (SAND) approach. As an optimizer, the code NPSOL was used which is based on a sequential quadratic programming (SQP) algorithm. The structures were modeled by the finite element method. The finite element related input to NPSOL was automatically generated from the input decks of such standard FEM/optimization codes as NASTRAN or ASTROS, with the stiffness matrices, at present, extracted from the FEM code ANALYZE. In order to avoid ill-conditioned matrices that can be encountered when the global stiffness equations are used as additional nonlinear equality constraints in the SAND approach (with the displacements as additional variables), the matrix displacement method was applied. In this approach, the element stiffness equations are used as constraints instead of the global stiffness equations, in conjunction with the nodal force equilibrium equations. This approach adds the element forces as variables to the system. Since, for complex structures and the associated large and very sparce matrices, the execution times of the optimization code became excessive due to the large number of required constraint gradient evaluations, the Kreisselmeier-Steinhauser function approach was used to decrease the computational effort by reducing the nonlinear equality constraint system to essentially a single combined constraint equation. As the linear equality and inequality constraints require much less computational effort to evaluate, they were kept in their previous form to limit the complexity of the KS function evaluation. To date, the standard three-bar, ten-bar, and 72-bar trusses have been tested. For the standard SAND approach, correct results were obtained for all three trusses although convergence became slower for the 72-bar truss. When the matrix displacement method was used, correct results were still obtained, but the execution times became excessive due to the large number of constraint gradient evaluations required. Using the KS function, the computational effort dropped, but the optimization seemed to become less robust. The investigation of this phenomenon is continuing. As an alternate approach, the code MINOS for the optimization of sparse matrices can be applied to the problem in lieu of the Kreisselmeier-Steinhauser function. This investigation is underway.

A stochastic Markov chain model to describe lung cancer growth and metastasis.

PubMed

Newton, Paul K; Mason, Jeremy; Bethel, Kelly; Bazhenova, Lyudmila A; Nieva, Jorge; Kuhn, Peter

2012-01-01

A stochastic Markov chain model for metastatic progression is developed for primary lung cancer based on a network construction of metastatic sites with dynamics modeled as an ensemble of random walkers on the network. We calculate a transition matrix, with entries (transition probabilities) interpreted as random variables, and use it to construct a circular bi-directional network of primary and metastatic locations based on postmortem tissue analysis of 3827 autopsies on untreated patients documenting all primary tumor locations and metastatic sites from this population. The resulting 50 potential metastatic sites are connected by directed edges with distributed weightings, where the site connections and weightings are obtained by calculating the entries of an ensemble of transition matrices so that the steady-state distribution obtained from the long-time limit of the Markov chain dynamical system corresponds to the ensemble metastatic distribution obtained from the autopsy data set. We condition our search for a transition matrix on an initial distribution of metastatic tumors obtained from the data set. Through an iterative numerical search procedure, we adjust the entries of a sequence of approximations until a transition matrix with the correct steady-state is found (up to a numerical threshold). Since this constrained linear optimization problem is underdetermined, we characterize the statistical variance of the ensemble of transition matrices calculated using the means and variances of their singular value distributions as a diagnostic tool. We interpret the ensemble averaged transition probabilities as (approximately) normally distributed random variables. The model allows us to simulate and quantify disease progression pathways and timescales of progression from the lung position to other sites and we highlight several key findings based on the model.

Analysis of methylglyoxal in water and biological matrices by capillary zone electrophoresis with diode array detection.

PubMed

do Rosário, Pedro Miguel Alvaro; Cordeiro, Carlos A Alves; Freire, Ana Ponces; Nogueira, José M Florêncio

2005-05-01

We describe a new method for the determination of methylglyoxal in water and biological matrices, using o-phenylenediamine as derivatizing agent and solid-phase extraction followed by capillary zone electrophoresis with diode array detection. 25 mM sodium phosphate running buffers at pH 2.2, 30 kV, and 25 degrees C allowed the best instrumental conditions for the optimum separation of methylglyoxal in a suitable analytical time (< 10 min), using an uncoated fused-silica capillary of 75 microm inner diameter and an effective length of 45.1 cm with an extended light path and the wavelength set to 200 nm. Under optimized instrumental conditions, good reproducibility of the migration time (< 1.1%), precision (< 5%), an excellent linear dynamic range from 0.1 to 3.6 mg/L (r(2) = 0.9997), and low limits of detection (7.2 microg/L) were obtained for methylglyoxal measurements, using the internal standard methodology. Assays on laboratory-spiked tap and ground water samples allowed a remarkable accuracy, presenting yields of 95.0 +/- 4.3 and 94.0 +/- 1.1%, respectively, and good performance to determine methylglyoxal in beer and yeast cells suspensions matrices was also obtained at trace level. The present methodology is a cost-effective alternative for routine quality control analysis, showing to be reliable, sensitive, and with a low sample volume requirement to monitor methylglyoxal in water and biological matrices.

Response of selected binomial coefficients to varying degrees of matrix sparseness and to matrices with known data interrelationships

USGS Publications Warehouse

Archer, A.W.; Maples, C.G.

1989-01-01

Numerous departures from ideal relationships are revealed by Monte Carlo simulations of widely accepted binomial coefficients. For example, simulations incorporating varying levels of matrix sparseness (presence of zeros indicating lack of data) and computation of expected values reveal that not only are all common coefficients influenced by zero data, but also that some coefficients do not discriminate between sparse or dense matrices (few zero data). Such coefficients computationally merge mutually shared and mutually absent information and do not exploit all the information incorporated within the standard 2 ?? 2 contingency table; therefore, the commonly used formulae for such coefficients are more complicated than the actual range of values produced. Other coefficients do differentiate between mutual presences and absences; however, a number of these coefficients do not demonstrate a linear relationship to matrix sparseness. Finally, simulations using nonrandom matrices with known degrees of row-by-row similarities signify that several coefficients either do not display a reasonable range of values or are nonlinear with respect to known relationships within the data. Analyses with nonrandom matrices yield clues as to the utility of certain coefficients for specific applications. For example, coefficients such as Jaccard, Dice, and Baroni-Urbani and Buser are useful if correction of sparseness is desired, whereas the Russell-Rao coefficient is useful when sparseness correction is not desired. ?? 1989 International Association for Mathematical Geology.

Validation of QuEChERS method for the determination of some pesticide residues in two apple varieties.

PubMed

Tiryaki, Osman

2016-10-02

This study was undertaken to validate the "quick, easy, cheap, effective, rugged and safe" (QuEChERS) method using Golden Delicious and Starking Delicious apple matrices spiked at 0.1 maximum residue limit (MRL), 1.0 MRL and 10 MRL levels of the four pesticides (chlorpyrifos, dimethoate, indoxacarb and imidacloprid). For the extraction and cleanup, original QuEChERS method was followed, then the samples were subjected to liquid chromatography-triple quadrupole mass spectrometry (LC-MS/MS) for chromatographic analyses. According to t test, matrix effect was not significant for chlorpyrifos in both sample matrices, but it was significant for dimethoate, indoxacarb and imidacloprid in both sample matrices. Thus, matrix-matched calibration (MC) was used to compensate matrix effect and quantifications were carried out by using MC. The overall recovery of the method was 90.15% with a relative standard deviation of 13.27% (n = 330). Estimated method detection limit of analytes blew the MRLs. Some other parameters of the method validation, such as recovery, precision, accuracy and linearity were found to be within the required ranges.

Regarding retrievals of methane in the atmosphere from IASI/Metop spectra and their comparison with ground-based FTIR measurements data

NASA Astrophysics Data System (ADS)

Khamatnurova, M. Yu.; Gribanov, K. G.; Zakharov, V. I.; Rokotyan, N. V.; Imasu, R.

2017-11-01

The algorithm for atmospheric methane distribution retrieval in atmosphere from IASI spectra has been developed. The feasibility of Levenberg-Marquardt method for atmospheric methane total column amount retrieval from the spectra measured by IASI/METOP modified for the case of lack of a priori covariance matrices for methane vertical profiles is studied in this paper. Method and algorithm were implemented into software package together with iterative estimation of a posteriori covariance matrices and averaging kernels for each individual retrieval. This allows retrieval quality selection using the properties of both types of matrices. Methane (XCH4) retrieval by Levenberg-Marquardt method from IASI/METOP spectra is presented in this work. NCEP/NCAR reanalysis data provided by ESRL (NOAA, Boulder, USA) were taken as initial guess. Surface temperature, air temperature and humidity vertical profiles are retrieved before methane vertical profile retrieval. The data retrieved from ground-based measurements at the Ural Atmospheric Station and data of L2/IASI standard product were used for the verification of the method and results of methane retrieval from IASI/METOP spectra.

Efficient Numerical Diagonalization of Hermitian 3 × 3 Matrices

NASA Astrophysics Data System (ADS)

Kopp, Joachim

A very common problem in science is the numerical diagonalization of symmetric or hermitian 3 × 3 matrices. Since standard "black box" packages may be too inefficient if the number of matrices is large, we study several alternatives. We consider optimized implementations of the Jacobi, QL, and Cuppen algorithms and compare them with an alytical method relying on Cardano's formula for the eigenvalues and on vector cross products for the eigenvectors. Jacobi is the most accurate, but also the slowest method, while QL and Cuppen are good general purpose algorithms. The analytical algorithm outperforms the others by more than a factor of 2, but becomes inaccurate or may even fail completely if the matrix entries differ greatly in magnitude. This can mostly be circumvented by using a hybrid method, which falls back to QL if conditions are such that the analytical calculation might become too inaccurate. For all algorithms, we give an overview of the underlying mathematical ideas, and present detailed benchmark results. C and Fortran implementations of our code are available for download from .

Extractive Atmospheric Pressure Photoionization (EAPPI) Mass Spectrometry: Rapid Analysis of Chemicals in Complex Matrices.

PubMed

Liu, Chengyuan; Yang, Jiuzhong; Wang, Jian; Hu, Yonghua; Zhao, Wan; Zhou, Zhongyue; Qi, Fei; Pan, Yang

2016-10-01

Extractive atmospheric pressure photoionization (EAPPI) mass spectrometry was designed for rapid qualitative and quantitative analysis of chemicals in complex matrices. In this method, an ultrasonic nebulization system was applied to sample extraction, nebulization, and vaporization. Mixed with a gaseous dopant, vaporized analytes were ionized through ambient photon-induced ion-molecule reactions, and were mass-analyzed by a high resolution time-of-flight mass spectrometer (TOF-MS). After careful optimization and testing with pure sample solution, EAPPI was successfully applied to the fast screening of capsules, soil, natural products, and viscous compounds. Analysis was completed within a few seconds without the need for preseparation. Moreover, the quantification capability of EAPPI for matrices was evaluated by analyzing six polycyclic aromatic hydrocarbons (PAHs) in soil. The correlation coefficients (R (2) ) for standard curves of all six PAHs were above 0.99, and the detection limits were in the range of 0.16-0.34 ng/mg. In addition, EAPPI could also be used to monitor organic chemical reactions in real time. Graphical Abstract ᅟ.

Calibration of Ge gamma-ray spectrometers for complex sample geometries and matrices

NASA Astrophysics Data System (ADS)

Semkow, T. M.; Bradt, C. J.; Beach, S. E.; Haines, D. K.; Khan, A. J.; Bari, A.; Torres, M. A.; Marrantino, J. C.; Syed, U.-F.; Kitto, M. E.; Hoffman, T. J.; Curtis, P.

2015-11-01

A comprehensive study of the efficiency calibration and calibration verification of Ge gamma-ray spectrometers was performed using semi-empirical, computational Monte-Carlo (MC), and transfer methods. The aim of this study was to evaluate the accuracy of the quantification of gamma-emitting radionuclides in complex matrices normally encountered in environmental and food samples. A wide range of gamma energies from 59.5 to 1836.0 keV and geometries from a 10-mL jar to 1.4-L Marinelli beaker were studied on four Ge spectrometers with the relative efficiencies between 102% and 140%. Density and coincidence summing corrections were applied. Innovative techniques were developed for the preparation of artificial complex matrices from materials such as acidified water, polystyrene, ethanol, sugar, and sand, resulting in the densities ranging from 0.3655 to 2.164 g cm-3. They were spiked with gamma activity traceable to international standards and used for calibration verifications. A quantitative method of tuning MC calculations to experiment was developed based on a multidimensional chi-square paraboloid.

Positive-entropy Hamiltonian systems on Nilmanifolds via scattering

NASA Astrophysics Data System (ADS)

Butler, Leo T.

2014-10-01

Let Σ be a compact quotient of T4, the Lie group of 4 × 4 upper triangular matrices with unity along the diagonal. The Lie algebra {\\mathfrak t}4 of T4 has the standard basis {Xij} of matrices with 0 everywhere but in the (i, j) entry, which is unity. Let g be the Carnot metric, a sub-Riemannian metric, on T4 for which Xi, i+1, (i = 1, 2, 3), is an orthonormal basis. Montgomery, Shapiro and Stolin showed that the geodesic flow of g is algebraically non-integrable. This paper proves that the geodesic flow of that Carnot metric on TΣ has positive topological entropy and its Euler field is real-analytically non-integrable. It extends earlier work by Butler and Gelfreich.

Performance of customized DCT quantization tables on scientific data

NASA Technical Reports Server (NTRS)

Ratnakar, Viresh; Livny, Miron

1994-01-01

We show that it is desirable to use data-specific or customized quantization tables for scaling the spatial frequency coefficients obtained using the Discrete Cosine Transform (DCT). DCT is widely used for image and video compression (MP89, PM93) but applications typically use default quantization matrices. Using actual scientific data gathered from divers sources such as spacecrafts and electron-microscopes, we show that the default compression/quality tradeoffs can be significantly improved upon by using customized tables. We also show that significant improvements are possible for the standard test images Lena and Baboon. This work is part of an effort to develop a practical scheme for optimizing quantization matrices for any given image or video stream, under any given quality or compression constraints.

34 CFR 106.43 - Standards for measuring skill or progress in physical education classes.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 34 Education 1 2010-07-01 2010-07-01 false Standards for measuring skill or progress in physical... Education Programs or Activities Prohibited § 106.43 Standards for measuring skill or progress in physical education classes. If use of a single standard of measuring skill or progress in physical education classes...

Formulation of the proper equations for developing standards in coherent dual polarisation SAR imaging

NASA Astrophysics Data System (ADS)

Boerner, W.-M.; Kostinski, A. B.

1988-08-01

Crucial inconsistencies in the basic equations of radar polarimetry which are common in the literature were detected. The formulations of the polarization state definitions given in the IEEE/ANSI Standards 149-1979 are in error. These and other inconsistencies and conceptual errors are discussed. The correct formulae for the proposed revision of the polarimetric standards together with a well-defined and consistent procedure for measuring target scattering matrices in monostatic and bistatic arrangements are given. The proposed procedure can be applied to an arbitrary measurement process in any general elliptical polarization basis.

New approach on trace analysis of triclosan in personal care products, biological and environmental matrices.

PubMed

Silva, Ana Rita M; Nogueira, J M F

2008-02-15

Stir bar sorptive extraction and liquid desorption followed by high performance liquid chromatography with diode array detection (SBSE-LD-LC-DAD) is proposed for the determination of triclosan in personal care products, biological and environmental matrices, which is included in the priority lists, set by several international regulatory organizations. Instrumental conditions and experimental parameters that affecting SBSE-LD efficiency are fully discussed. Throughout systematic assays on 25 mL water samples spiked at the 10.0 microg L(-1) level, it had been established that stir bars coated with 126 microL of polydimethylsiloxane, an equilibrium time of 1h (1000 rpm) and acetonitrile under sonification (60 min) as back-extraction solvent, allowed the best analytical performance to determine triclosan in water matrices. From the data obtained, good recovery and remarkable repeatability were attained, providing experimental average yields (78.5+/-2.2%), although slightly lower than the theoretical equilibrium (99.7%) described by the octanol-water partition coefficients (K(PDMS/W)0.9992) from 0.4 to 108.0 microg L(-1). The application of the present method to determine triclosan in real matrices such as commercial toothpaste, saliva and urban wastewater samples, allowed appropriate selectivity, high sensitivity and accuracy using the standard addition methodology. The proposed method showed to be feasible and sensitive with a low-sample volume requirement to monitor triclosan in personal care products, biological and environmental matrices at the trace level, in compliance with international regulatory directives.

Trace level voltammetric determination of heavy metals and total mercury in tea matrices (Camellia sinensis).

PubMed

Melucci, Dora; Locatelli, Marcello; Locatelli, Clinio

2013-12-01

An analytical procedure regarding the voltammetric determination of mercury(II), copper(II), lead(II), cadmium(II) and zinc(II) by square wave anodic stripping voltammetry (SWASV) in matrices involved in food chain is proposed. In particular, tea leaves were analyzed as real samples. The digestion of each matrix was carried out using a concentrated HCl-HNO3-H2SO4 acidic attack mixture; 0.01 mol L(-1) EDTA-Na2+ 0.15 mol L(-1) NaCl + 0.5 mol L(-1) HCl was employed as the supporting electrolyte. The voltammetric measurements were carried out using a conventional three electrode cell, employing, as working electrodes, a gold electrode (GE) and a stationary hanging mercury drop electrode (HMDE). The analytical procedure has been verified on the standard reference materials Spinach Leaves NIST-SRM 1570a, Tomato Leaves NIST-SRM 1573a and Apple Leaves NIST-SRM 1515. For all the elements, the precision as repeatability, expressed as relative standard deviation (sr) was of the order of 3-5%, while the trueness, expressed as relative error (e) was of the order of 3-7%. Once set up on the standard reference materials, the analytical procedure was applied to commercial tea leaves samples. A critical comparison with spectroscopic measurements is also discussed.

Aeronautics: An Educator's Guide with Activities in Science, Mathematics, and Technology Education.

ERIC Educational Resources Information Center

National Aeronautics and Space Administration, Washington, DC.

This educator's guide, developed for students in grades 2-4, discusses the field of aeronautics. It begins with education standards and skill matrices for the classroom activities, a description of the National Aeronautics and Space Administration (NASA) aeronautics mission, and a brief history of aeronautics. Activities are written for the…

A bottom-up approach to the strong CP problem

NASA Astrophysics Data System (ADS)

Diaz-Cruz, J. L.; Hollik, W. G.; Saldana-Salazar, U. J.

2018-05-01

The strong CP problem is one of many puzzles in the theoretical description of elementary particle physics that still lacks an explanation. While top-down solutions to that problem usually comprise new symmetries or fields or both, we want to present a rather bottom-up perspective. The main problem seems to be how to achieve small CP violation in the strong interactions despite the large CP violation in weak interactions. In this paper, we show that with minimal assumptions on the structure of mass (Yukawa) matrices, they do not contribute to the strong CP problem and thus we can provide a pathway to a solution of the strong CP problem within the structures of the Standard Model and no extension at the electroweak scale is needed. However, to address the flavor puzzle, models based on minimal SU(3) flavor groups leading to the proposed flavor matrices are favored. Though we refrain from an explicit UV completion of the Standard Model, we provide a simple requirement for such models not to show a strong CP problem by construction.

Quantitative Proteomics via High Resolution MS Quantification: Capabilities and Limitations

PubMed Central

Higgs, Richard E.; Butler, Jon P.; Han, Bomie; Knierman, Michael D.

2013-01-01

Recent improvements in the mass accuracy and resolution of mass spectrometers have led to renewed interest in label-free quantification using data from the primary mass spectrum (MS1) acquired from data-dependent proteomics experiments. The capacity for higher specificity quantification of peptides from samples enriched for proteins of biological interest offers distinct advantages for hypothesis generating experiments relative to immunoassay detection methods or prespecified peptide ions measured by multiple reaction monitoring (MRM) approaches. Here we describe an evaluation of different methods to post-process peptide level quantification information to support protein level inference. We characterize the methods by examining their ability to recover a known dilution of a standard protein in background matrices of varying complexity. Additionally, the MS1 quantification results are compared to a standard, targeted, MRM approach on the same samples under equivalent instrument conditions. We show the existence of multiple peptides with MS1 quantification sensitivity similar to the best MRM peptides for each of the background matrices studied. Based on these results we provide recommendations on preferred approaches to leveraging quantitative measurements of multiple peptides to improve protein level inference. PMID:23710359

Raney Distributions and Random Matrix Theory

NASA Astrophysics Data System (ADS)

Forrester, Peter J.; Liu, Dang-Zheng

2015-03-01

Recent works have shown that the family of probability distributions with moments given by the Fuss-Catalan numbers permit a simple parameterized form for their density. We extend this result to the Raney distribution which by definition has its moments given by a generalization of the Fuss-Catalan numbers. Such computations begin with an algebraic equation satisfied by the Stieltjes transform, which we show can be derived from the linear differential equation satisfied by the characteristic polynomial of random matrix realizations of the Raney distribution. For the Fuss-Catalan distribution, an equilibrium problem characterizing the density is identified. The Stieltjes transform for the limiting spectral density of the singular values squared of the matrix product formed from inverse standard Gaussian matrices, and standard Gaussian matrices, is shown to satisfy a variant of the algebraic equation relating to the Raney distribution. Supported on , we show that it too permits a simple functional form upon the introduction of an appropriate choice of parameterization. As an application, the leading asymptotic form of the density as the endpoints of the support are approached is computed, and is shown to have some universal features.

TU-AB-BRA-04: Quantitative Radiomics: Sensitivity of PET Textural Features to Image Acquisition and Reconstruction Parameters Implies the Need for Standards

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nyflot, MJ; Yang, F; Byrd, D

Purpose: Despite increased use of heterogeneity metrics for PET imaging, standards for metrics such as textural features have yet to be developed. We evaluated the quantitative variability caused by image acquisition and reconstruction parameters on PET textural features. Methods: PET images of the NEMA IQ phantom were simulated with realistic image acquisition noise. 35 features based on intensity histograms (IH), co-occurrence matrices (COM), neighborhood-difference matrices (NDM), and zone-size matrices (ZSM) were evaluated within lesions (13, 17, 22, 28, 33 mm diameter). Variability in metrics across 50 independent images was evaluated as percent difference from mean for three phantom girths (850,more » 1030, 1200 mm) and two OSEM reconstructions (2 iterations, 28 subsets, 5 mm FWHM filtration vs 6 iterations, 28 subsets, 8.6 mm FWHM filtration). Also, patient sample size to detect a clinical effect of 30% with Bonferroni-corrected α=0.001 and 95% power was estimated. Results: As a class, NDM features demonstrated greatest sensitivity in means (5–50% difference for medium girth and reconstruction comparisons and 10–100% for large girth comparisons). Some IH features (standard deviation, energy, entropy) had variability below 10% for all sensitivity studies, while others (kurtosis, skewness) had variability above 30%. COM and ZSM features had complex sensitivities; correlation, energy, entropy (COM) and zone percentage, short-zone emphasis, zone-size non-uniformity (ZSM) had variability less than 5% while other metrics had differences up to 30%. Trends were similar for sample size estimation; for example, coarseness, contrast, and strength required 12, 38, and 52 patients to detect a 30% effect for the small girth case but 38, 88, and 128 patients in the large girth case. Conclusion: The sensitivity of PET textural features to image acquisition and reconstruction parameters is large and feature-dependent. Standards are needed to ensure that prospective trials which incorporate textural features are properly designed to detect clinical endpoints. Supported by NIH grants R01 CA169072, U01 CA148131, NCI Contract (SAIC-Frederick) 24XS036-004, and a research contract from GE Healthcare.« less

[Progress in environmental exposure of organophosphate flame retardants].

PubMed

Ding, J J; Yang, F X

2017-06-06

Organophosphate flame retardants (OPFRs), which have both great properties of flame retardation and plasticization, are currently widely used as additive flame retardants. Due to the restriction and phase-out of brominated flame retardants (BFRs), the market demand for OPFRs as excellent alternatives of BFRs has been rapid increasing. OPFRs can be slowly released into the environment during production and application. Some OPFRs might be persistent in the environment. As a result, OPFRs have been detected in various matrices in the environment and are expected to accumulate in human body through various pathways. OPFRs may cause adverse effects to human health as some of them have been identified as neurotoxicants, reproductive toxicants and potential carcinogens. The article summarized the occurrence and patterns of OPFRs in various environmental matrices such as air, dust, water, food and so on, and in human specimens, estimates the exposure status through different pathways and body burdens of OPFRs. The expected hotspots of OPFRs were also discussed in the future.

Synthetic biology meets tissue engineering

PubMed Central

Davies, Jamie A.; Cachat, Elise

2016-01-01

Classical tissue engineering is aimed mainly at producing anatomically and physiologically realistic replacements for normal human tissues. It is done either by encouraging cellular colonization of manufactured matrices or cellular recolonization of decellularized natural extracellular matrices from donor organs, or by allowing cells to self-organize into organs as they do during fetal life. For repair of normal bodies, this will be adequate but there are reasons for making unusual, non-evolved tissues (repair of unusual bodies, interface to electromechanical prostheses, incorporating living cells into life-support machines). Synthetic biology is aimed mainly at engineering cells so that they can perform custom functions: applying synthetic biological approaches to tissue engineering may be one way of engineering custom structures. In this article, we outline the ‘embryological cycle’ of patterning, differentiation and morphogenesis and review progress that has been made in constructing synthetic biological systems to reproduce these processes in new ways. The state-of-the-art remains a long way from making truly synthetic tissues, but there are now at least foundations for future work. PMID:27284030

Recent Advances in On-Line Methods Based on Extraction for Speciation Analysis of Chromium in Environmental Matrices.

PubMed

Trzonkowska, Laura; Leśniewska, Barbara; Godlewska-Żyłkiewicz, Beata

2016-07-03

The biological activity of Cr(III) and Cr(VI) species, their chemical behavior, and toxic effects are dissimilar. The speciation analysis of Cr(III) and Cr(VI) in environmental matrices is then of great importance and much research has been devoted to this area. This review presents recent developments in on-line speciation analysis of chromium in such samples. Flow systems have proved to be excellent tools for automation of sample pretreatment, separation/preconcentration of chromium species, and their detection by various instrumental techniques. Analytical strategies used in chromium speciation analysis discussed in this review are divided into categories based on selective extraction/separation of chromium species on solid sorbents and liquid-liquid extraction of chromium species. The most popular strategy is that based on solid-phase extraction. Therefore, this review shows the potential of novel materials designed and used for selective binding of chromium species. The progress in miniaturization of measurement systems is also presented.

Exoskeletal cuticle differentiation during intramarsupial development of Porcellio scaber (Crustacea: Isopoda).

PubMed

Mrak, Polona; Znidaršič, Nada; Zagar, Kristina; Ceh, Miran; Strus, Jasna

2014-09-01

Exoskeletal crustacean cuticle is a calcified apical extracellular matrix of epidermal cells, illustrating the chitin-based organic scaffold for biomineralization. Studies of cuticle formation during molting reveal significant dynamics and complexity of the assembly processes, while cuticle formation during embryogenesis is poorly investigated. This study reveals in the terrestrial isopod Porcellio scaber, the ultrastructural organization of the differentiating precuticular matrices and exoskeletal cuticles during embryonic and larval intramarsupial development. The composition of the epidermal matrices was obtained by WGA lectin labelling and EDXS analysis. At least two precuticular matrices, consisting of loosely arranged material with overlying electron dense lamina, are secreted by the epidermis in the mid-stage embryo. The prehatching embryo is the earliest developmental stage with a cuticular matrix consisting of an epicuticle and a procuticle, displaying WGA binding and forming cuticular scales. In newly hatched marsupial larva manca, a new cuticle is formed and calcium sequestration in the cuticle is evident. Progression of larval development leads to the cuticle thickening, structural differentiation of cuticular layers and prominent cuticle calcification. Morphological characteristics of exoskeleton renewal in marsupial manca are described. Elaborated cuticle in marsupial larvae indicates the importance of the exoskeleton in protection and support of the larval body in the marsupium and during the release of larvae in the external environment. Copyright © 2014 Elsevier Ltd. All rights reserved.

Embryonic cardiomyocytes beat best on a matrix with heart-like elasticity: scar-like rigidity inhibits beating

PubMed Central

Engler, Adam J.; Carag-Krieger, Christine; Johnson, Colin P.; Raab, Matthew; Tang, Hsin-Yao; Speicher, David W.; Sanger, Joseph W.; Sanger, Jean M.; Discher, Dennis E.

2009-01-01

Summary Fibrotic rigidification following a myocardial infarct is known to impair cardiac output, and it is also known that cardiomyocytes on rigid culture substrates show a progressive loss of rhythmic beating. Here, isolated embryonic cardiomyocytes cultured on a series of flexible substrates show that matrices that mimic the elasticity of the developing myocardial microenvironment are optimal for transmitting contractile work to the matrix and for promoting actomyosin striation and 1-Hz beating. On hard matrices that mechanically mimic a post-infarct fibrotic scar, cells overstrain themselves, lack striated myofibrils and stop beating; on very soft matrices, cells preserve contractile beating for days in culture but do very little work. Optimal matrix leads to a strain match between cell and matrix, and suggests dynamic differences in intracellular protein structures. A ‘cysteine shotgun’ method of labeling the in situ proteome reveals differences in assembly or conformation of several abundant cytoskeletal proteins, including vimentin, filamin and myosin. Combined with recent results, which show that stem cell differentiation is also highly sensitive to matrix elasticity, the methods and analyses might be useful in the culture and assessment of cardiogenesis of both embryonic stem cells and induced pluripotent stem cells. The results described here also highlight the need for greater attention to fibrosis and mechanical microenvironments in cell therapy and development. PMID:18957515

A 3D printed nano bone matrix for characterization of breast cancer cell and osteoblast interactions

NASA Astrophysics Data System (ADS)

Zhu, Wei; Castro, Nathan J.; Cui, Haitao; Zhou, Xuan; Boualam, Benchaa; McGrane, Robert; Glazer, Robert I.; Zhang, Lijie Grace

2016-08-01

Bone metastasis is one of the most prevalent complications of late-stage breast cancer, in which the native bone matrix components, including osteoblasts, are intimately involved in tumor progression. The development of a successful in vitro model would greatly facilitate understanding the underlying mechanism of breast cancer bone invasion as well as provide a tool for effective discovery of novel therapeutic strategies. In the current study, we fabricated a series of in vitro bone matrices composed of a polyethylene glycol hydrogel and nanocrystalline hydroxyapatite of varying concentrations to mimic the native bone microenvironment for the investigation of breast cancer bone metastasis. A stereolithography-based three-dimensional (3D) printer was used to fabricate the bone matrices with precisely controlled architecture. The interaction between breast cancer cells and osteoblasts was investigated in the optimized bone matrix. Using a Transwell® system to separate the two cell lines, breast cancer cells inhibited osteoblast proliferation, while osteoblasts stimulated breast cancer cell growth, whereas, both cell lines increased IL-8 secretion. Breast cancer cells co-cultured with osteoblasts within the 3D bone matrix formed multi-cellular spheroids in comparison to two-dimensional monolayers. These findings validate the use of our 3D printed bone matrices as an in vitro metastasis model, and highlights their potential for investigating breast cancer bone metastasis.

Validation of an LC-MS/MS method for the quantification of choline-related compounds and phospholipids in foods and tissues.

PubMed

Xiong, Yeping; Zhao, Yuan-Yuan; Goruk, Sue; Oilund, Kirsten; Field, Catherine J; Jacobs, René L; Curtis, Jonathan M

2012-12-12

A hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC LC-MS/MS) method was developed and validated to simultaneously quantify six aqueous choline-related compounds and eight major phospholipids classes in a single run. HILIC chromatography was coupled to positive ion electrospray mass spectrometry. A combination of multiple scan modes including precursor ion scan, neutral loss scan and multiple reaction monitoring was optimized for the determination of each compound or class in a single LC/MS run. This work developed a simplified extraction scheme in which both free choline and related compounds along with phospholipids were extracted into a homogenized phase using chloroform/methanol/water (1:2:0.8) and diluted into methanol for the analysis of target compounds in a variety of sample matrices. The analyte recoveries were evaluated by spiking tissues and food samples with two isotope-labeled internal standards, PC-d(3) and Cho-d(3). Recoveries of between 90% and 115% were obtained by spiking a range of sample matrices with authentic standards containing all 14 of the target analytes. The precision of the analysis ranged from 1.6% to 13%. Accuracy and precision was comparable to that obtained by quantification of selected phospholipid classes using (31)P NMR. A variety of sample matrices including egg yolks, human diets and animal tissues were analyzed using the validated method. The measurements of total choline in selected foods were found to be in good agreement with values obtained from the USDA choline database. Copyright © 2012 Elsevier B.V. All rights reserved.

Analysis of Volatile Markers for Virgin Olive Oil Aroma Defects by SPME-GC/FID: Possible Sources of Incorrect Data.

PubMed

Oliver-Pozo, Celia; Aparicio-Ruiz, Ramón; Romero, Inmaculada; García-González, Diego L

2015-12-09

The need to explain virgin olive oil (VOO) aroma descriptors by means of volatiles has raised interest in applying analytical techniques for trapping and quantitating volatiles. Static headspace sampling with solid phase microextraction (SPME) as trapping material is one of the most applied solutions for analyzing volatiles. The use of an internal standard and the determination of the response factors of the main volatiles seem to guarantee the correct determination of volatile concentrations in VOOs by SPME-GC/FID. This paper, however, shows that the competition phenomena between volatiles in their adsorption to the SPME fiber, inherent in static headspace sampling, may affect the quantitation. These phenomena are more noticeable in the particular case of highly odorant matrices, such as rancid and vinegary VOOs with high intensity of defect. The competition phenomena can modify the measurement sensitivity, which can be observed in volatile quantitation as well as in the recording of internal standard areas in different matrices. This paper analyzes the bias of the peak areas and concentrations of those volatiles that are markers for each sensory defect of VOOs (rancid, vinegary, musty, and fusty) when the intensity and complexity of aroma are increased. Of the 17 volatile markers studied in this work, 10 presented some anomalies in the quantitation in highly odorant matrices due the competition phenomena. However, quantitation was not affected in the concentration ranges at which each volatile marker is typically found in the defective oils they were characteristic of, validating their use as markers.

Clifford Algebra Implying Three Fermion Generations Revisited

NASA Astrophysics Data System (ADS)

Krolikowski, Wojciech

2002-09-01

The author's idea of algebraic compositeness of fundamental particles, allowing to understand the existence in Nature of three fermion generations, is revisited. It is based on two postulates. Primo, for all fundamental particles of matter the Dirac square-root procedure √ {p2} → {Γ }(N)p works, leading to a sequence N = 1,2,3, ... of Dirac-type equations, where four Dirac-type matrices {Γ }(N)μ are embedded into a Clifford algebra via a Jacobi definition introducing four ``centre-of-mass'' and (N-1)× four ``relative'' Dirac-type matrices. These define one ``centre-of-mass'' and (N-1) ``relative'' Dirac bispinor indices. Secundo, the ``centre-of-mass'' Dirac bispinor index is coupled to the Standard Model gauge fields, while (N-1) ``relative'' Dirac bispinor indices are all free indistinguishable physical objects obeying Fermi statistics along with the Pauli principle which requires the full antisymmetry with respect to ``relative'' Dirac indices. This allows only for three Dirac-type equations with N = 1,3,5 in the case of N odd, and two with N = 2,4 in the case of N even. The first of these results implies unavoidably the existence of three and only three generations of fundamental fermions, namely leptons and quarks, as labelled by the Standard Model signature. At the end, a comment is added on the possible shape of Dirac 3x3 mass matrices for four sorts of spin-1/2 fundamental fermions appearing in three generations. For charged leptons a prediction is mτ = 1776.80 MeV, when the input of experimental me and mμ is used.

An anthropomorphic phantom for quantitative evaluation of breast MRI.

PubMed

Freed, Melanie; de Zwart, Jacco A; Loud, Jennifer T; El Khouli, Riham H; Myers, Kyle J; Greene, Mark H; Duyn, Jeff H; Badano, Aldo

2011-02-01

In this study, the authors aim to develop a physical, tissue-mimicking phantom for quantitative evaluation of breast MRI protocols. The objective of this phantom is to address the need for improved standardization in breast MRI and provide a platform for evaluating the influence of image protocol parameters on lesion detection and discrimination. Quantitative comparisons between patient and phantom image properties are presented. The phantom is constructed using a mixture of lard and egg whites, resulting in a random structure with separate adipose- and glandular-mimicking components. T1 and T2 relaxation times of the lard and egg components of the phantom were estimated at 1.5 T from inversion recovery and spin-echo scans, respectively, using maximum-likelihood methods. The image structure was examined quantitatively by calculating and comparing spatial covariance matrices of phantom and patient images. A static, enhancing lesion was introduced by creating a hollow mold with stereolithography and filling it with a gadolinium-doped water solution. Measured phantom relaxation values fall within 2 standard errors of human values from the literature and are reasonably stable over 9 months of testing. Comparison of the covariance matrices of phantom and patient data demonstrates that the phantom and patient data have similar image structure. Their covariance matrices are the same to within error bars in the anterior-posterior direction and to within about two error bars in the right-left direction. The signal from the phantom's adipose-mimicking material can be suppressed using active fat-suppression protocols. A static, enhancing lesion can also be included with the ability to change morphology and contrast agent concentration. The authors have constructed a phantom and demonstrated its ability to mimic human breast images in terms of key physical properties that are relevant to breast MRI. This phantom provides a platform for the optimization and standardization of breast MRI imaging protocols for lesion detection and characterization.

Apparent transient effects of recent "ecstasy" use on cognitive performance and extrapyramidal signs in human subjects.

PubMed

Smith, Ryan M; Tivarus, Madalina; Campbell, Heather L; Hillier, Ashleigh; Beversdorf, David Q

2006-09-01

Our purpose is to investigate cognitive performance and extrapyramidal function early after ecstasy use. Ecstasy, containing 3,4 methylenedioxymethamphetamine, has shown evidence of causing cognitive deficits and parkinsonian signs. Previous research has examined cognitive performance after a period of prolonged abstinence, but research assessing the early effects of ecstasy after recent use is limited despite temporal neurochemical differences demonstrated in nonhuman models. This study compared task performance between 13 ecstasy users (10 to 15 h postdrug use) and a control group on a battery of neuropsychologic assessments while matching for education level, sleep deprivation, and premorbid IQ. The groups were also compared on measures relating to parkinsonian signs. The ecstasy subjects showed impairments on measures of executive function as evaluated by Raven's Standard Progressive Matrices (SPM) and the Wisconsin Card Sorting Task (WCST). Short-delay free recall memory was also impaired in ecstasy subjects on the California Verbal Learning Test (CVLT-II). No extrapyramidal motor impairments were detected. These deficits resemble deficits previously reported in chronic ecstasy use but also seem to reveal transient impairments in executive function. Future research is needed to better understand the neurologic and neuropsychologic implications of ecstasy use across time and extent of use.

Developmental changes in real life decision making: performance on a gambling task previously shown to depend on the ventromedial prefrontal cortex.

PubMed

Crone, Eveline A; van der Molen, Maurits W

2004-01-01

Patients with bilateral lesions of the ventromedial prefrontal cortex, when performing gambling tasks modeling real-life decision-making, opt for choices that yield high immediate gains in spite of higher future losses. Under the hypothesis that the prefrontal cortex is the last brain region to mature, it was examined whether young children would show a similar preference for immediate prospects. In Experiment 1, 4 age groups (6-9, 10-12, 13-15 and 18-25 years olds) performed 2 versions of a computerized variant of the original Iowa gambling task under 3 different feedback conditions (no feedback, global feedback, and option-specific feedback) and completed the Raven Standard Progressive Matrices as an index of inductive reasoning ability. In Experiment 2, 3 age groups (7-8, 11-12, and 15-16 year olds) performed both task versions in addition to a working memory task ("Digit Span Backwards"). Results showed a developmental increase in the sensitivity to future consequences, positive or negative, that could not be explained by developmental changes in working memory capacity or inductive reasoning. It was concluded that young children share with ventromedial prefrontal patients the failure to anticipate on future outcomes.

Questioning the rule of thumb: can verbal tasks be administered during the CVLT-II delay interval?

PubMed

Williams, Bethany R; Donovick, Peter J

2008-09-01

In the manual for the California Verbal Learning Test - II (CVLT-II), the authors suggest that nonverbal, rather than verbal, tasks be administered during the delay interval between administrations of the Short- and Long-Delay Recall trials of this test. They contend that this method minimizes the retroactive interference produced by intervening tasks. The purpose of the current study was to compare the extent to which verbal and nonverbal intervening tasks produce retroactive interference on CVLT-II List A recall following the long-delay. Participants in the present study were 120 undergraduate students. All participants completed the CVLT-II, and were randomly assigned to a group in which they were administered either a verbal (WAIS-III Vocabulary or Peabody Picture Vocabulary Test - IIIB) or nonverbal (Raven's Standard Progressive Matrices or WAIS-III Block Design) intervening task during the long-delay interval of the CVLT-II. Statistical analyses revealed that regardless of the type of intervening task given, participants in all groups recalled the same number of words and produced a similar number of intrusions during the CVLT-II recall trials. This indicates that not all verbal tasks produce retroactive effects beyond those produced by nonverbal tasks.

Re-examining the cognitive phenotype in autism: a study with young Chinese children.

PubMed

Lam, Yan Grace

2013-12-01

Deficits consistently found in autism include an impaired "theory of mind", weak central coherence, and deficits in executive function. The current study examined whether this traditional cluster of symptoms existed in a group of Chinese-speaking children with autism. Sixteen high-functioning, non-retarded children with autism were matched to 16 typically developing (TD) children on gender, non-verbal IQ and age. Non-verbal IQ's of all participants were measured using the Raven Progressive Matrices. Each participant was tested individually on measures of "theory of mind", central coherence and executive function. Results indicated that most, but not all, participants with autism performed significantly poorer on two standard measures of first-order "theory of mind," although there was no significant difference on two other measures of that domain. As expected, they performed significantly worse on executive function tasks. However, the hypothesis of weak central coherence in autism was not substantiated. There was no evidence that these three cognitive impairments co-existed in individuals with autism. More likely, each of these deficits appears singly or in pair instead of forming a cluster. Copyright © 2013 Elsevier Ltd. All rights reserved.

Validation of a Sulfuric Acid Digestion Method for Inductively Coupled Plasma Mass Spectrometry Quantification of TiO2 Nanoparticles.

PubMed

Watkins, Preston S; Castellon, Benjamin T; Tseng, Chiyen; Wright, Moncie V; Matson, Cole W; Cobb, George P

2018-04-13

A consistent analytical method incorporating sulfuric acid (H 2 SO 4 ) digestion and ICP-MS quantification has been developed for TiO 2 quantification in biotic and abiotic environmentally relevant matrices. Sample digestion in H 2 SO 4 at 110°C provided consistent results without using hydrofluoric acid or microwave digestion. Analysis of seven replicate samples for four matrices on each of 3 days produced Ti recoveries of 97% ± 2.5%, 91 % ± 4.0%, 94% ± 1.8%, and 73 % ± 2.6% (mean ± standard deviation) from water, fish tissue, periphyton, and sediment, respectively. The method demonstrated consistent performance in analysis of water collected over a 1 month.

Cork-based activated carbons as supported adsorbent materials for trace level analysis of ibuprofen and clofibric acid in environmental and biological matrices.

PubMed

Neng, N R; Mestre, A S; Carvalho, A P; Nogueira, J M F

2011-09-16

In this contribution, powdered activated carbons (ACs) from cork waste were supported for bar adsorptive micro-extraction (BAμE), as novel adsorbent phases for the analysis of polar compounds. By combining this approach with liquid desorption followed by high performance liquid chromatography with diode array detection (BAμE(AC)-LD/HPLC-DAD), good analytical performance was achieved using clofibric acid (CLOF) and ibuprofen (IBU) model compounds in environmental and biological matrices. Assays performed on 30 mL water samples spiked at the 25.0 μg L(-1) level yielded recoveries around 80% for CLOF and 95% for IBU, under optimized experimental conditions. The ACs textural and surface chemistry properties were correlated with the results obtained. The analytical performance showed good precision (<15%), suitable detection limits (0.24 and 0.78 μg L(-1) for CLOF and IBU, respectively) and good linear dynamic ranges (r(2)>0.9922) from 1.0 to 600.0 μg L(-1). By using the standard addition methodology, the application of the present approach to environmental water and urine matrices allowed remarkable performance at the trace level. The proposed methodology proved to be a viable alternative for acidic pharmaceuticals analysis, showing to be easy to implement, reliable, sensitive and requiring low sample volume to monitor these priority compounds in environmental and biological matrices. Copyright © 2011 Elsevier B.V. All rights reserved.

Dispersions of Carbon nanotubes in Polymer Matrices

NASA Technical Reports Server (NTRS)

Wise, Kristopher Eric (Inventor); Park, Cheol (Inventor); Siochi, Emilie J. (Inventor); Harrison, Joycelyn S. (Inventor); Lillehei, Peter T. (Inventor); Lowther, Sharon E. (Inventor)

2010-01-01

Dispersions of carbon nanotubes exhibiting long term stability are based on a polymer matrix having moieties therein which are capable of a donor-acceptor complexation with carbon nanotubes. The carbon nanotubes are introduced into the polymer matrix and separated therein by standard means. Nanocomposites produced from these dispersions are useful in the fabrication of structures, e.g., lightweight aerospace structures.

A Complete Multimode Equivalent-Circuit Theory for Electrical Design

PubMed Central

Williams, Dylan F.; Hayden, Leonard A.; Marks, Roger B.

1997-01-01

This work presents a complete equivalent-circuit theory for lossy multimode transmission lines. Its voltages and currents are based on general linear combinations of standard normalized modal voltages and currents. The theory includes new expressions for transmission line impedance matrices, symmetry and lossless conditions, source representations, and the thermal noise of passive multiports. PMID:27805153

NHEXAS PHASE I ARIZONA STUDY--STANDARD OPERATING PROCEDURE FOR ANALYSIS OF PESTICIDE SAMPLES BY GC/ECD (BCO-L-24.0)

EPA Science Inventory

The purpose of this SOP is to describe the methods used for detection and quantification by gas chromatography electron capture detector (GC/ECD) of pesticides in a variety of matrices, including air, house dust, soil, handwipes, and surface wipes. Other SOP's detail the extract...

NHEXAS PHASE I ARIZONA STUDY--STANDARD OPERATING PROCEDURE FOR ANALYSIS OF PESTICIDE SAMPLES BY GC/MS (BCO-L-15.1)

EPA Science Inventory

The purpose of this SOP is to describe the methods used for detection and quantification by gas chromatography/mass spectrometry (GC/MS) of pesticides in a variety of matrices, including air, house dust, soil, and handwipes. This analysis involves automated gas GC/MS analysis us...

NMR 1D-imaging of water infiltration into mesoporous matrices.

PubMed

Le Feunteun, Steven; Diat, Olivier; Guillermo, Armel; Poulesquen, Arnaud; Podor, Renaud

2011-04-01

It is shown that coupling nuclear magnetic resonance (NMR) 1D-imaging with the measure of NMR relaxation times and self-diffusion coefficients can be a very powerful approach to investigate fluid infiltration into porous media. Such an experimental design was used to study the very slow seeping of pure water into hydrophobic materials. We consider here three model samples of nuclear waste conditioning matrices which consist in a dispersion of NaNO(3) (highly soluble) and/or BaSO(4) (poorly soluble) salt grains embedded in a bitumen matrix. Beyond studying the moisture progression according to the sample depth, we analyze the water NMR relaxation times and self-diffusion coefficients along its 1D-concentration profile to obtain spatially resolved information on the solution properties and on the porous structure at different scales. It is also shown that, when the relaxation or self-diffusion properties are multimodal, the 1D-profile of each water population is recovered. Three main levels of information were disclosed along the depth-profiles. They concern (i) the water uptake kinetics, (ii) the salinity and the molecular dynamics of the infiltrated solutions and (iii) the microstructure of the water-filled porosities: open networks coexisting with closed pores. All these findings were fully validated and enriched by NMR cryoporometry experiments and by performing environmental scanning electronic microscopy observations. Surprisingly, results clearly show that insoluble salts enhance the water progression and thereby increase the capability of the material to uptake water. Copyright © 2011 Elsevier Inc. All rights reserved.

The multifacet graphically contracted function method. II. A general procedure for the parameterization of orthogonal matrices and its application to arc factors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shepard, Ron; Brozell, Scott R.; Gidofalvi, Gergely

2014-08-14

Practical algorithms are presented for the parameterization of orthogonal matrices Q ∈ R {sup m×n} in terms of the minimal number of essential parameters (φ). Both square n = m and rectangular n < m situations are examined. Two separate kinds of parameterizations are considered, one in which the individual columns of Q are distinct, and the other in which only Span(Q) is significant. The latter is relevant to chemical applications such as the representation of the arc factors in the multifacet graphically contracted function method and the representation of orbital coefficients in SCF and DFT methods. The parameterizations aremore » represented formally using products of elementary Householder reflector matrices. Standard mathematical libraries, such as LAPACK, may be used to perform the basic low-level factorization, reduction, and other algebraic operations. Some care must be taken with the choice of phase factors in order to ensure stability and continuity. The transformation of gradient arrays between the Q and (φ) parameterizations is also considered. Operation counts for all factorizations and transformations are determined. Numerical results are presented which demonstrate the robustness, stability, and accuracy of these algorithms.« less

Determination of ametoctradin residue in fruits and vegetables by modified quick, easy, cheap, effective, rugged, and safe method using ultra-performance liquid chromatography/tandem mass spectrometry.

PubMed

Hu, Mingfeng; Liu, Xingang; Dong, Fengshou; Xu, Jun; Li, Shasha; Xu, Hanqing; Zheng, Yongquan

2015-05-15

A rapid, effective and sensitive method to quantitatively determine ametoctradin residue in apple, cucumber, cabbage, tomato and grape was developed and validated using ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS). The target compound was determined in less than 5.0 min using an electrospray ionisation source in positive mode (ESI+). The limit of detection was below 0.043 μg kg(-1), whereas the limits of quantification did not exceed 0.135 μg kg(-1) in all five matrices. The method showed excellent linearity (R(2)>0.9969) for the target compound. Recovery studies were performed in all matrices at three spiked levels (1, 10 and 100 μg L(-1)). The mean recoveries from five matrices ranged from 81.81% to 100.1%, with intra-day relative standard deviations (RSDr) in the range of 0.65-7.88% for the test compound. This method will be useful for the quick and routine detection of ametoctradin residues in potato, grape, cucumber, apple and tomato. Copyright © 2014 Elsevier Ltd. All rights reserved.

HS-SPME determination of volatile carbonyl and carboxylic compounds in different matrices.

PubMed

Stashenko, Elena E; Mora, Amanda L; Cervantes, Martha E; Martínez, Jairo R

2006-07-01

Specific chromatographic methodologies are developed for the analysis of carboxylic acids (C(2)-C(6), benzoic) and aldehydes (C(2)-C(10)) of low molecular weight in diverse matrices, such as air, automotive exhaust gases, human breath, and aqueous matrices. For carboxylic acids, the method is based on their reaction with pentafluorobenzyl bromide in aqueous solution, followed by the separation and identification of the resultant pentafluorobenzyl esters by means of headspace (HS)-solid-phase microextraction (SPME) combined with gas chromatography (GC) and electron capture detection (ECD). Detection limits in the microg/m(3) range are reached, with relative standard deviation (RSD) less than 10% and linear response (R(2) > 0.99) over two orders of magnitude. The analytical methodology for aldehydes is based on SPME with simultaneous derivatization of the analytes on the fiber, by reaction with pentafluorophenylhydrazine. The derivatization reagent is previously deposited on the SPME fiber, which is then exposed to the gaseous matrix or the HS of the sample solution. The pentafluorophenyl hydrazones formed on the fiber are analyzed selectively by means of GC-ECD, with detection limits in the ng/m(3) range, RSD less than 10%, and linear response (R(2) > 0.99) over two orders of magnitude.

Multiplex quantification of protein toxins in human biofluids and food matrices using immunoextraction and high-resolution targeted mass spectrometry.

PubMed

Dupré, Mathieu; Gilquin, Benoit; Fenaille, François; Feraudet-Tarisse, Cécile; Dano, Julie; Ferro, Myriam; Simon, Stéphanie; Junot, Christophe; Brun, Virginie; Becher, François

2015-08-18

The development of rapid methods for unambiguous identification and precise quantification of protein toxins in various matrices is essential for public health surveillance. Nowadays, analytical strategies classically rely on sensitive immunological assays, but mass spectrometry constitutes an attractive complementary approach thanks to direct measurement and protein characterization ability. We developed here an innovative multiplex immuno-LC-MS/MS method for the simultaneous and specific quantification of the three potential biological warfare agents, ricin, staphylococcal enterotoxin B, and epsilon toxin, in complex human biofluids and food matrices. At least 7 peptides were targeted for each toxin (43 peptides in total) with a quadrupole-Orbitrap high-resolution instrument for exquisite detection specificity. Quantification was performed using stable isotope-labeled toxin standards spiked early in the sample. Lower limits of quantification were determined at or close to 1 ng·mL(-1). The whole process was successfully applied to the quantitative analysis of toxins in complex samples such as milk, human urine, and plasma. Finally, we report new data on toxin stability with no evidence of toxin degradation in milk in a 48 h time frame, allowing relevant quantitative toxin analysis for samples collected in this time range.

Development of an EMC3-EIRENE Synthetic Imaging Diagnostic

NASA Astrophysics Data System (ADS)

Meyer, William; Allen, Steve; Samuell, Cameron; Lore, Jeremy

2017-10-01

2D and 3D flow measurements are critical for validating numerical codes such as EMC3-EIRENE. Toroidal symmetry assumptions preclude tomographic reconstruction of 3D flows from single camera views. In addition, the resolution of the grids utilized in numerical code models can easily surpass the resolution of physical camera diagnostic geometries. For these reasons we have developed a Synthetic Imaging Diagnostic capability for forward projection comparisons of EMC3-EIRENE model solutions with the line integrated images from the Doppler Coherence Imaging diagnostic on DIII-D. The forward projection matrix is 2.8 Mpixel by 6.4 Mcells for the non-axisymmetric case we present. For flow comparisons, both simple line integral, and field aligned component matrices must be calculated. The calculation of these matrices is a massive embarrassingly parallel problem and performed with a custom dispatcher that allows processing platforms to join mid-problem as they become available, or drop out if resources are needed for higher priority tasks. The matrices are handled using standard sparse matrix techniques. Prepared by LLNL under Contract DE-AC52-07NA27344. This material is based upon work supported by the U.S. DOE, Office of Science, Office of Fusion Energy Sciences. LLNL-ABS-734800.

Determination of chloramphenicol residues in meat, seafood, egg, honey, milk, plasma and urine with liquid chromatography-tandem mass spectrometry, and the validation of the method based on 2002/657/EC.

PubMed

Rønning, Helene Thorsen; Einarsen, Kristin; Asp, Tone Normann

2006-06-23

A simple and rapid method for the determination and confirmation of chloramphenicol in several food matrices with LC-MS/MS was developed. Following addition of d5-chloramphenicol as internal standard, meat, seafood, egg, honey and milk samples were extracted with acetonitrile. Chloroform was then added to remove water. After evaporation, the residues were reconstituted in methanol/water (3+4) before injection. The urine and plasma samples were after addition of internal standard applied to a Chem Elut extraction cartridge, eluted with ethyl acetate, and hexane washed. Also these samples were reconstituted in methanol/water (3+4) after evaporation. By using an MRM acquisition method in negative ionization mode, the transitions 321-->152, 321-->194 and 326-->157 were used for quantification, confirmation and internal standard, respectively. Quantification of chloramphenicol positive samples regardless of matrix could be achieved with a common water based calibration curve. The validation of the method was based on EU-decision 2002/657 and different ways of calculating CCalpha and CCbeta were evaluated. The common CCalpha and CCbeta for all matrices were 0.02 and 0.04 microg/kg for the 321-->152 ion transition, and 0.02 and 0.03 microg/kg for the 321-->194 ion transition. At fortification level 0.1 microg/kg the within-laboratory reproducibility is below 25%.

Methods of analysis by the U.S. Geological Survey Organic Geochemistry Research Group; determination of glyphosate, aminomethylphosphonic acid, and glufonsinate in water using online solid-phase extraction and high-performance liquid chromat

USGS Publications Warehouse

Lee, E.A.; Strahan, A.P.; Thurman, E.M.

2001-01-01

An analytical method for the determination of glyphosate, its principal degradation compound, aminomethylphosphonic acid (AMPA), and glufosinate in water with varying matrices has been developed. Four different sample matrices fortified at 0.2 and 2.0 ?g/L (micrograms per liter) were analyzed using precolumn derivatization with 9-fluorenylmethylchloroformate (FMOC). After derivatization, cleanup and concentration were accomplished using automated online solid-phase extraction followed by elution with the mobile phase allowing for direct injection into a liquid chromatograph/mass spectrometer (LC/MS). Analytical conditions for MS detection were optimized, and quantitation was carried out using the following representative ions: 390 and 168 for glyphosate; 332, 110, and 136 for AMPA; and 402, 180, and 206 for glufosinate. Matrix effects were minimized by utilizing standard addition for quantification and an isotope-labeled glyphosate (2-13C,15N) as the internal standard. Method detection limits (MDLs) were 0.084 ?g/L for glyphosate, 0.078 ?g/L for AMPA, and 0.057 ?g/L for glufosinate. The method reporting limits (MRLs) were set at 0.1 ?g/L for all three compounds. The mean recovery values ranged from 88.0 to 128.7 percent, and relative standard deviation values ranged from 5.6 to 32.6 percent.

Lack of robustness of textural measures obtained from 3D brain tumor MRIs impose a need for standardization.

PubMed

Molina, David; Pérez-Beteta, Julián; Martínez-González, Alicia; Martino, Juan; Velasquez, Carlos; Arana, Estanislao; Pérez-García, Víctor M

2017-01-01

Textural measures have been widely explored as imaging biomarkers in cancer. However, their robustness under dynamic range and spatial resolution changes in brain 3D magnetic resonance images (MRI) has not been assessed. The aim of this work was to study potential variations of textural measures due to changes in MRI protocols. Twenty patients harboring glioblastoma with pretreatment 3D T1-weighted MRIs were included in the study. Four different spatial resolution combinations and three dynamic ranges were studied for each patient. Sixteen three-dimensional textural heterogeneity measures were computed for each patient and configuration including co-occurrence matrices (CM) features and run-length matrices (RLM) features. The coefficient of variation was used to assess the robustness of the measures in two series of experiments corresponding to (i) changing the dynamic range and (ii) changing the matrix size. No textural measures were robust under dynamic range changes. Entropy was the only textural feature robust under spatial resolution changes (coefficient of variation under 10% in all cases). Textural measures of three-dimensional brain tumor images are not robust neither under dynamic range nor under matrix size changes. Standards should be harmonized to use textural features as imaging biomarkers in radiomic-based studies. The implications of this work go beyond the specific tumor type studied here and pose the need for standardization in textural feature calculation of oncological images.

An Analysis of the Max-Min Texture Measure.

DTIC Science & Technology

1982-01-01

PANC 33 D2 Confusion Matrices for Scene A, IR 34 D3 Confusion Matrices for Scene B, PANC 35 D4 Confusion Matrices for Scene B, IR 36 D5 Confusion...Matrices for Scene C, PANC 37 D6 Confusion Matrices for Scene C, IR 38 D7 Confusion Matrices for Scene E, PANC 39 D8 Confusion Matrices for Scene E, IR 40...D9 Confusion Matrices for Scene H, PANC 41 DIO Confusion Matrices for Scene H, JR 42 3 .D 10CnuinMtie o cn ,IR4 AN ANALYSIS OF THE MAX-MIN TEXTURE

Use of high-resolution mass spectrometry to investigate a metabolite interference during liquid chromatography/tandem mass spectrometric quantification of a small molecule in toxicokinetic study samples.

PubMed

Furlong, Michael; Bessire, Andrew; Song, Wei; Huntington, Christopher; Groeber, Elizabeth

2010-07-15

During routine liquid chromatography/tandem mass spectrometric (LC/MS/MS) bioanalysis of a small molecule analyte in rat serum samples from a toxicokinetic study, an unexpected interfering peak was observed in the extracted ion chromatogram of the internal standard. No interfering peaks were observed in the extracted ion chromatogram of the analyte. The dose-dependent peak area response and peak area response versus time profiles of the interfering peak suggested that it might have been related to a metabolite of the dosed compound. Further investigation using high-resolution mass spectrometry led to unequivocal identification of the interfering peak as an N-desmethyl metabolite of the parent analyte. High-resolution mass spectrometry (HRMS) was also used to demonstrate that the interfering response of the metabolite in the multiple reaction monitoring (MRM) channel of the internal standard was due to an isobaric relationship between the (13)C-isotope of the metabolite and the internal standard (i.e., common precursor ion mass), coupled with a metabolite product ion with identical mass to the product ion used in the MRM transition of the internal standard. These results emphasize (1) the need to carefully evaluate internal standard candidates with regard to potential interferences from metabolites during LC/MS/MS method development, validation and bioanalysis of small molecule analytes in biological matrices; (2) the value of HRMS as a tool to investigate unexpected interferences encountered during LC/MS/MS analysis of small molecules in biological matrices; and (3) the potential for interference regardless of choice of IS and therefore the importance of conducting assay robustness on incurred in vitro or in vivo study samples. Copyright 2010 John Wiley & Sons, Ltd.

Comprehensive proteomic characterization of stem cell-derived extracellular matrices.

PubMed

Ragelle, Héloïse; Naba, Alexandra; Larson, Benjamin L; Zhou, Fangheng; Prijić, Miralem; Whittaker, Charles A; Del Rosario, Amanda; Langer, Robert; Hynes, Richard O; Anderson, Daniel G

2017-06-01

In the stem-cell niche, the extracellular matrix (ECM) serves as a structural support that additionally provides stem cells with signals that contribute to the regulation of stem-cell function, via reciprocal interactions between cells and components of the ECM. Recently, cell-derived ECMs have emerged as in vitro cell culture substrates to better recapitulate the native stem-cell microenvironment outside the body. Significant changes in cell number, morphology and function have been observed when mesenchymal stem cells (MSC) were cultured on ECM substrates as compared to standard tissue-culture polystyrene (TCPS). As select ECM components are known to regulate specific stem-cell functions, a robust characterization of cell-derived ECM proteomic composition is critical to better comprehend the role of the ECM in directing cellular processes. Here, we characterized and compared the protein composition of ECM produced in vitro by bone marrow-derived MSC, adipose-derived MSC and neonatal fibroblasts from different donors, employing quantitative proteomic methods. Each cell-derived ECM displayed a specific and unique matrisome signature, yet they all shared a common set of proteins. We evaluated the biological response of cells cultured on the different matrices and compared them to cells on standard TCPS. The matrices lead to differential survival and gene-expression profiles among the cell types and as compared to TCPS, indicating that the cell-derived ECMs influence each cell type in a different manner. This general approach to understanding the protein composition of different tissue-specific and cell-derived ECM will inform the rational design of defined systems and biomaterials that recapitulate critical ECM signals for stem-cell culture and tissue engineering. Copyright © 2017 Elsevier Ltd. All rights reserved.

Determination of mycotoxins in different food commodities by ultra-high-pressure liquid chromatography coupled to triple quadrupole mass spectrometry.

PubMed

Beltrán, Eduardo; Ibáñez, María; Sancho, Juan Vicente; Hernández, Félix

2009-06-01

A rapid multianalyte-multiclass method with little sample manipulation has been developed for the simultaneous determination of eleven mycotoxins in different food commodities by using ultra-high-pressure liquid chromatography coupled to triple quadrupole mass spectrometry (UHPLC/MS/MS). Toxins were extracted from the samples with acetonitrile/water (80:20, v/v) 0.1% HCOOH and, after a two-fold dilution with water, directly injected into the system. Thanks to the fast high-resolution separation of UHPLC, the eleven mycotoxins were separated by gradient elution in only 4 min. The method has been validated in three food matrices (maize kernels, dry pasta (wheat), and eight-multicereal babyfood (wheat, maize, rice, oat, barley, rye, sorghum, millet)) at four different concentration levels. Satisfactory recoveries were obtained (70-110%) and precision (expressed as relative standard deviation) was typically below 15% with very few exceptions. Quantification of samples was carried out with matrix-matched standards calibration. The lowest concentration successfully validated in sample was as low as 0.5 microg/kg for aflatoxins and ochratoxin A in babyfood, and 20 microg/kg for the rest of the selected mycotoxins in all matrices tested. Deoxynivalenol could be only validated at 200 microg/kg, due the poor sensitivity for this mycotoxin analysis. With only two exceptions (HT-2 and deoxynivalenol), the limits of detection (LODs), estimated for a signal-to-noise ratio of 3 from the chromatograms of samples spiked at the lowest level validated, varied between 0.1 and 1 microg/kg in the three food matrices tested. The method was applied to the analysis of different kinds of samples. Positive findings were confirmed by acquiring two transitions (Q quantification, q confirmation) and evaluating the Q/q ratio. Copyright (c) 2009 John Wiley & Sons, Ltd.

Residue analysis of four diacylhydrazine insecticides in fruits and vegetables by Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) method using ultra-performance liquid chromatography coupled to tandem mass spectrometry.

PubMed

Liu, Xingang; Xu, Jun; Dong, Fengshou; Li, Yuanbo; Song, Wenchen; Zheng, Yongquan

2011-08-01

The new analytical method using Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) procedure for simultaneous determination of diacylhydrazine insecticide residues in fruits and vegetables was developed using ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS). The four insecticides (tebufenozide, methoxfenozide, chromafenozide, and halofenozide) were extracted from six fruit and vegetable matrices using acetonitrile and subsequently cleaned up using primary secondary amine (PSA) or octadecylsilane (C18) as sorbent prior to UPLC-MS/MS analysis. The determination of the target compounds was achieved in less than 3.0 min using an electrospray ionization source in positive mode (ESI+) for tebufenozide, methoxfenozide, and halofenozide and in negative mode (ESI-) for chromafenozide. The limits of detection were below 0.6 μg kg(-1), while the limit of quantification did not exceed 2 μg kg(-1) in different matrices. The QuEChERS procedure by using two sorbents (PSA and C18) and the matrix-matched standards gave satisfactory recoveries and relative standard deviation (RSD) values in different matrices at four spiked levels (0.01, 0.05, 0.1, and 1 mg kg(-1)). The overall average recoveries for this method in apple, grape, cucumber, tomato, cabbage, and spinach at four levels ranged from 74.2% to 112.5% with RSDs in the range of 1.4-13.8% (n = 5) for all analytes. This study provides a theoretical basis for China to draw up maximum residue limits and analytical method for diacylhydrazine insecticide in vegetables and fruits.

Progress report 3 of cooperative program for design, fabrication, and testing of high modulus composite helicopter shafting

NASA Technical Reports Server (NTRS)

Wright, C. C.; Baker, D. J.

1980-01-01

This report describes the third phase of work, the objective of which was to overcome the excessive brittleness of the previously developed UH-1 helicopter tail rotor drive shaft design which demonstrated a shaft train weight savings of 53.1% over the current 2024-T3 aluminum shaft train. A materials impact program demonstrated exceptionally noteworthy performance of two woven constructions containing E-glass and PRD 49-III (designation later changed to KEVLAR 49) fibers in an epoxy resin matrix. Thermoplastic matrices and PRD 49-III fiber provided impact resistance at low weight which was superior to composites having the same fiber in a thermoset resin matrix. A design, fabrication, and test program showed that shaft impact resistance could be improved over the previously developed graphite composite design at a cost in shaft train rate savings. The shaft train weight savings of the most impact tolerant construction was 4.0% over the current aluminum shaft train. Alternating plies of graphite and glass appear to provide substantially greater tube impact durability than that provided by hybridization of the two fibers into one tape wound to a ply design equivalent in strength and stiffness to that of the alternating ply design. Recommendations were made to continue research work to exploit the potential for more impact-durable structures through the use of KEVLAR 49 fiber, woven structures, thermoplastic matrices and THORNEL 50-S/KEVLAR 49 blends with thermoset matrices.

Periodic GMP Matrices

NASA Astrophysics Data System (ADS)

Eichinger, Benjamin

2016-07-01

We recall criteria on the spectrum of Jacobi matrices such that the corresponding isospectral torus consists of periodic operators. Motivated by those known results for Jacobi matrices, we define a new class of operators called GMP matrices. They form a certain Generalization of matrices related to the strong Moment Problem. This class allows us to give a parametrization of almost periodic finite gap Jacobi matrices by periodic GMP matrices. Moreover, due to their structural similarity we can carry over numerous results from the direct and inverse spectral theory of periodic Jacobi matrices to the class of periodic GMP matrices. In particular, we prove an analogue of the remarkable ''magic formula'' for this new class.

Suspension Matrices for Improved Schwann-Cell Survival after Implantation into the Injured Rat Spinal Cord

PubMed Central

Patel, Vivek; Joseph, Gravil; Patel, Amit; Patel, Samik; Bustin, Devin; Mawson, David; Tuesta, Luis M.; Puentes, Rocio; Ghosh, Mousumi

2010-01-01

Abstract Trauma to the spinal cord produces endogenously irreversible tissue and functional loss, requiring the application of therapeutic approaches to achieve meaningful restoration. Cellular strategies, in particular Schwann-cell implantation, have shown promise in overcoming many of the obstacles facing successful repair of the injured spinal cord. Here, we show that the implantation of Schwann cells as cell suspensions with in-situ gelling laminin:collagen matrices after spinal-cord contusion significantly enhances long-term cell survival but not proliferation, as well as improves graft vascularization and the degree of axonal in-growth over the standard implantation vehicle, minimal media. The use of a matrix to suspend cells prior to implantation should be an important consideration for achieving improved survival and effectiveness of cellular therapies for future clinical application. PMID:20144012

Development of an Analytical Method for Dibutyl Phthalate Determination Using Surrogate Analyte Approach

PubMed Central

Farzanehfar, Vahid; Faizi, Mehrdad; Naderi, Nima; Kobarfard, Farzad

2017-01-01

Dibutyl phthalate (DBP) is a phthalic acid ester and is widely used in polymeric products to make them more flexible. DBP is found in almost every plastic material and is believed to be persistent in the environment. Various analytical methods have been used to measure DBP in different matrices. Considering the ubiquitous nature of DBP, the most important challenge in DBP analyses is the contamination of even analytical grade organic solvents with this compound and lack of availability of a true blank matrix to construct the calibration line. Standard addition method or using artificial matrices reduce the precision and accuracy of the results. In this study a surrogate analyte approach that is based on using deuterium labeled analyte (DBP-d4) to construct the calibration line was applied to determine DBP in hexane samples. PMID:28496469

Quantification of short chain amines in aqueous matrices using liquid chromatography electrospray ionization tandem mass spectrometry.

PubMed

Viidanoja, Jyrki

2017-01-13

A new liquid chromatography-electrospray ionization-tandem Mass Spectrometry (LC-ESI-MS/MS) method was developed for the determination of more than 20 C 1 -C 6 alkyl and alkanolamines in aqueous matrices. The method employs Hydrophilic Interaction Liquid Chromatography Multiple Reaction Monitoring (HILIC-MRM) with a ZIC-pHILIC column and four stable isotope labeled amines as internal standards for signal normalization and quantification of the amines. The method was validated using a refinery process water sample that was obtained from a cooling cycle of crude oil distillation. The averaged within run precision, between run precision and accuracy were generally within 2-10%, 1-9% and 80-120%, respectively, depending on the analyte and concentration level. Selected aqueous process samples were analyzed with the method. Copyright © 2016 Elsevier B.V. All rights reserved.

Efficient and Robust Signal Approximations

DTIC Science & Technology

2009-05-01

otherwise. Remark. Permutation matrices are both orthogonal and doubly- stochastic [62]. We will now show how to further simplify the Robust Coding...reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching...Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 Keywords: signal processing, image compression, independent component analysis , sparse

Detection of beryllium in digested autopsy tissues by inductively coupled plasma mass spectrometry using a high matrix interface configuration.

PubMed

Larivière, Dominic; Tremblay, Mélodie; Durand-Jézéquel, Myriam; Tolmachev, Sergei

2012-04-01

This article describes a robust methodology using the combination of instrumental design (high matrix interface-HMI), sample dilution and internal standardization for the quantification of beryllium (Be) in various digested autopsy tissues using inductively coupled plasma mass spectrometry. The applicability of rhodium as a proper internal standard for Be was demonstrated in three types of biological matrices (i.e., femur, hair, lung tissues). Using HMI, it was possible to achieve instrumental detection limits and sensitivity of 0.6 ng L(-1) and 157 cps L ng(-1), respectively. Resilience to high salt matrices of the HMI setup was also highlighted using bone mimicking solution ([Ca(2+)] = 26 to 1,400 mg L(-1)), providing a 14-fold increase in tolerance and a 2.7-fold decrease in method detection limit compared to optimized experimental conditions obtained without the HMI configuration. Precision of the methodology to detect low levels of Be in autopsy samples was demonstrated using hair and blood certified reference materials. Be concentration ranging from 0.015 to 255 μg kg(-1) in autopsy samples obtained from the U.S. Transuranium and Uranium Registries were measured using the methodology presented.

Molecular t-matrices for Low-Energy Electron Diffraction (TMOL v1.1)

NASA Astrophysics Data System (ADS)

Blanco-Rey, Maria; de Andres, Pedro; Held, Georg; King, David A.

2004-08-01

We describe a FORTRAN-90 program that computes scattering t-matrices for a molecule. These can be used in a Low-Energy Electron Diffraction program to solve the molecular structural problem very efficiently. The intramolecular multiple scattering is computed within a Dyson-like approach, using free space Green propagators in a basis of spherical waves. The advantage of this approach is related to exploiting the chemical identity of the molecule, and to the simplicity to translate and rotate these t-matrices without performing a new multiple-scattering calculation for each configuration. FORTRAN-90 routines for rotating the resulting t-matrices using Wigner matrices are also provided. Program summaryTitle of program: TMOL Catalogue number: ADUF Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADUF Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland. Computers: Alpha ev6-21264 (700 MHz) and Pentium-IV. Operating systems: Digital UNIX V5.0 and Linux (Red Hat 8.0). Programming language: FORTRAN-90/95 (Compaq True64 compiler, and Intel Fortran Compiler 7.0 for Linux). High-speed storage required for the test run: minimum 64 Mbytes, it can grow to more depending on the system considered. Disk storage required: None. No. of bits in a word: 64 and 32. No. of lines in distributed program, including test data etc.: 5404 No. of bytes in distributed program, including test data etc.: 59 856 Distribution format: tar.gz Nature of problem: We describe the FORTRAN-90 program TMOL (v1.1) for the computation of non-diagonal scattering t-matrices for molecules or any other poly-atomic sub-unit of surface structures. These matrices can be used in an standard Low-Energy Electron Diffraction program, such as LEED90 or CLEED. Method of solution: A general non-diagonal t-matrix is assumed for the atoms or more general scatterers forming the molecule. The molecular t-matrix is solved adding the possible intramolecular multiple scattering events using Green's propagator formalism. The resulting t-matrix is referred to the mass centre of the molecule and can be easily translated with these propagators and rotated applying Wigner matrices. Typical running time: Calculating the t-matrix for a single energy takes a few seconds. Time depends on the maximum angular momentum quantum number, lmax, and the number of scatterers in the molecule, N. Running time scales as lmax6 and N3. References: [1] S. Andersson, J.B. Pendry, J. Phys. C: Solid St. Phys. 13 (1980) 3547. [2] A. Gonis, W.H. Butler, Multiple Scattering in Solids, Springer-Verlag, Berlin/New York, 2000.

SubVis: an interactive R package for exploring the effects of multiple substitution matrices on pairwise sequence alignment

PubMed Central

Coan, Heather B.; Youker, Robert T.

2017-01-01

Understanding how proteins mutate is critical to solving a host of biological problems. Mutations occur when an amino acid is substituted for another in a protein sequence. The set of likelihoods for amino acid substitutions is stored in a matrix and input to alignment algorithms. The quality of the resulting alignment is used to assess the similarity of two or more sequences and can vary according to assumptions modeled by the substitution matrix. Substitution strategies with minor parameter variations are often grouped together in families. For example, the BLOSUM and PAM matrix families are commonly used because they provide a standard, predefined way of modeling substitutions. However, researchers often do not know if a given matrix family or any individual matrix within a family is the most suitable. Furthermore, predefined matrix families may inaccurately reflect a particular hypothesis that a researcher wishes to model or otherwise result in unsatisfactory alignments. In these cases, the ability to compare the effects of one or more custom matrices may be needed. This laborious process is often performed manually because the ability to simultaneously load multiple matrices and then compare their effects on alignments is not readily available in current software tools. This paper presents SubVis, an interactive R package for loading and applying multiple substitution matrices to pairwise alignments. Users can simultaneously explore alignments resulting from multiple predefined and custom substitution matrices. SubVis utilizes several of the alignment functions found in R, a common language among protein scientists. Functions are tied together with the Shiny platform which allows the modification of input parameters. Information regarding alignment quality and individual amino acid substitutions is displayed with the JavaScript language which provides interactive visualizations for revealing both high-level and low-level alignment information. PMID:28674656

A uniform object-oriented solution to the eigenvalue problem for real symmetric and Hermitian matrices

NASA Astrophysics Data System (ADS)

Castro, María Eugenia; Díaz, Javier; Muñoz-Caro, Camelia; Niño, Alfonso

2011-09-01

We present a system of classes, SHMatrix, to deal in a unified way with the computation of eigenvalues and eigenvectors in real symmetric and Hermitian matrices. Thus, two descendant classes, one for the real symmetric and other for the Hermitian cases, override the abstract methods defined in a base class. The use of the inheritance relationship and polymorphism allows handling objects of any descendant class using a single reference of the base class. The system of classes is intended to be the core element of more sophisticated methods to deal with large eigenvalue problems, as those arising in the variational treatment of realistic quantum mechanical problems. The present system of classes allows computing a subset of all the possible eigenvalues and, optionally, the corresponding eigenvectors. Comparison with well established solutions for analogous eigenvalue problems, as those included in LAPACK, shows that the present solution is competitive against them. Program summaryProgram title: SHMatrix Catalogue identifier: AEHZ_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEHZ_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 2616 No. of bytes in distributed program, including test data, etc.: 127 312 Distribution format: tar.gz Programming language: Standard ANSI C++. Computer: PCs and workstations. Operating system: Linux, Windows. Classification: 4.8. Nature of problem: The treatment of problems involving eigensystems is a central topic in the quantum mechanical field. Here, the use of the variational approach leads to the computation of eigenvalues and eigenvectors of real symmetric and Hermitian Hamiltonian matrices. Realistic models with several degrees of freedom leads to large (sometimes very large) matrices. Different techniques, such as divide and conquer, can be used to factorize the matrices in order to apply a parallel computing approach. However, it is still interesting to have a core procedure able to tackle the computation of eigenvalues and eigenvectors once the matrix has been factorized to pieces of enough small size. Several available software packages, such as LAPACK, tackled this problem under the traditional imperative programming paradigm. In order to ease the modelling of complex quantum mechanical models it could be interesting to apply an object-oriented approach to the treatment of the eigenproblem. This approach offers the advantage of a single, uniform treatment for the real symmetric and Hermitian cases. Solution method: To reach the above goals, we have developed a system of classes: SHMatrix. SHMatrix is composed by an abstract base class and two descendant classes, one for real symmetric matrices and the other for the Hermitian case. The object-oriented characteristics of inheritance and polymorphism allows handling both cases using a single reference of the base class. The basic computing strategy applied in SHMatrix allows computing subsets of eigenvalues and (optionally) eigenvectors. The tests performed show that SHMatrix is competitive, and more efficient for large matrices, than the equivalent routines of the LAPACK package. Running time: The examples included in the distribution take only a couple of seconds to run.

Development of a multi-residue method for the determination of human and veterinary pharmaceuticals and some of their metabolites in aqueous environmental matrices by SPE-UHPLC-MS/MS.

PubMed

Paíga, P; Santos, L H M L M; Delerue-Matos, C

2017-02-20

The aim of the present work was to develop and validate a multi-residue method for the analysis of 33 human and veterinary pharmaceuticals (non-steroidal anti-inflammatory drugs (NSAIDs)/analgesics, antibiotics and psychiatric drugs), including some of their metabolites, in several aqueous environmental matrices: drinking water, surface water and wastewaters. The method is based on solid phase extraction (SPE) followed by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) and it was validated for different aqueous matrices, namely bottled water, tap water, seawater, river water and wastewaters, showing recoveries between 50% and 112% for the majority of the target analytes. The developed analytical methodology allowed method detection limits in the low nanograms per liter level. Method intra- and inter-day precision was under 8% and 11%, respectively, expressed as relative standard deviation. The developed method was applied to the analysis of drinking water (bottled and tap water), surface waters (seawater and river water) and wastewaters (wastewater treatment plant (WWTP) influent and effluent). Due to the selectivity and sensitivity of the optimized method, it was possible to detect pharmaceuticals in all the aqueous environmental matrices considered, including in bottled water at concentrations up to 31ngL -1 (salicylic acid). In general, non-steroidal anti-inflammatory drugs/analgesics was the therapeutic group most frequently detected, with the highest concentrations found in wastewaters (acetaminophen and the metabolite carboxyibuprofen at levels up to 615 and 120μgL -1 , respectively). Copyright © 2016 Elsevier B.V. All rights reserved.

A 10-minute measure of global cognition: Validation of the Brief Cognitive Assessment Tool for Schizophrenia (B-CATS).

PubMed

Hurford, Irene M; Ventura, Joseph; Marder, Stephen R; Reise, Steven P; Bilder, Robert M

2018-05-01

Schizophrenia is marked by a global cognitive impairment that contributes significantly to chronic disability and unemployment. As new treatments are developed for cognition in schizophrenia, clinicians require easily administered instruments to assess cognition. We previously developed a very brief cognitive battery (Bell et al., 2005). The Brief Cognitive Assessment Tool for Schizophrenia (B-CATS) was developed specifically to provide clinicians with a way to assess cognition in their patients with schizophrenia. Here, we report the results of a validity study comparing B-CATS to a larger neurocognitive battery, the Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) battery. Outpatients with schizophrenia (N=91) were administered the B-CATS and the non-overlapping tests of the MATRICS battery at two time points separated by 1month. They were also administered the UCSD Performance-based Skills Assessment-Brief (UPSA-B), a measure of functional capacity. The B-CATS has an administration time of approximately 10min. It demonstrates good test-retest reliability and internal consistency. It correlates 0.76 (p<0.01) with the MATRICS battery. The shorter B-CATS and the MATRICS battery correlate with the UPSA-B at 0.50 and 0.58 respectively. A 10-minute version of the B-CATS correlates highly with the "gold standard" neurocognitive battery that has an administration time of over 60min. Both measures correlate moderately with a measure of functional capacity. This brief battery was designed to allow clinicians to monitor cognitive change and better inform treatment decisions. Copyright © 2017 Elsevier B.V. All rights reserved.

Powdered activated carbons as effective phases for bar adsorptive micro-extraction (BAμE) to monitor levels of triazinic herbicides in environmental water matrices.

PubMed

Neng, N R; Mestre, A S; Carvalho, A P; Nogueira, J M F

2011-02-15

Bar adsorptive micro-extraction using three powdered activated carbons (ACs) as adsorbent phases followed by liquid desorption and high performance liquid chromatography with diode array detection (BAμE(ACs)-LD/HPLC-DAD), was developed to monitor triazinic herbicides (atrazine, simazine and terbutylazine) in environmental water matrices. ACs used present apparent surface areas around 1000 m(2) g(-1) with an important mesoporous volume and distinct surface chemistry characteristics (pH(PZC) ranging from 6.5 to 10.4). The textural and surface chemistry properties of the ACs adsorbent phases were correlated with the analytical data for a better understanding of the overall enrichment process. Assays performed on 10 mL water samples spiked at the 10.0 μg L(-1) levels under optimized experimental conditions yielded recoveries around 100% for the three herbicides under study. The analytical performance showed good precision (RSD<15.0%), convenient detection limits (≈0.1 μg L(-1)) and suitable linearity (1.0-12.0 μg L(-1)) with good correlation coefficients (r(2)>0.9914). By using the standard addition method, the application of the present method on real water matrices, such as surface water and wastewater, allowed very good performances at the trace level. The proposed methodology proved to be a suitable sorptive extraction alternative for the analysis of priority pollutants with polar characteristics, showing to be easy to implement, reliable, sensitive and requiring a low sample volume to monitor triazinic compounds in water matrices. Copyright © 2010 Elsevier B.V. All rights reserved.

Dynamic statistical optimization of GNSS radio occultation bending angles: advanced algorithm and performance analysis

NASA Astrophysics Data System (ADS)

Li, Y.; Kirchengast, G.; Scherllin-Pirscher, B.; Norman, R.; Yuan, Y. B.; Fritzer, J.; Schwaerz, M.; Zhang, K.

2015-08-01

We introduce a new dynamic statistical optimization algorithm to initialize ionosphere-corrected bending angles of Global Navigation Satellite System (GNSS)-based radio occultation (RO) measurements. The new algorithm estimates background and observation error covariance matrices with geographically varying uncertainty profiles and realistic global-mean correlation matrices. The error covariance matrices estimated by the new approach are more accurate and realistic than in simplified existing approaches and can therefore be used in statistical optimization to provide optimal bending angle profiles for high-altitude initialization of the subsequent Abel transform retrieval of refractivity. The new algorithm is evaluated against the existing Wegener Center Occultation Processing System version 5.6 (OPSv5.6) algorithm, using simulated data on two test days from January and July 2008 and real observed CHAllenging Minisatellite Payload (CHAMP) and Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) measurements from the complete months of January and July 2008. The following is achieved for the new method's performance compared to OPSv5.6: (1) significant reduction of random errors (standard deviations) of optimized bending angles down to about half of their size or more; (2) reduction of the systematic differences in optimized bending angles for simulated MetOp data; (3) improved retrieval of refractivity and temperature profiles; and (4) realistically estimated global-mean correlation matrices and realistic uncertainty fields for the background and observations. Overall the results indicate high suitability for employing the new dynamic approach in the processing of long-term RO data into a reference climate record, leading to well-characterized and high-quality atmospheric profiles over the entire stratosphere.

From near-infrared and Raman to surface-enhanced Raman spectroscopy: progress, limitations and perspectives in bioanalysis.

PubMed

Dumont, Elodie; De Bleye, Charlotte; Sacré, Pierre-Yves; Netchacovitch, Lauranne; Hubert, Philippe; Ziemons, Eric

2016-05-01

Over recent decades, spreading environmental concern entailed the expansion of green chemistry analytical tools. Vibrational spectroscopy, belonging to this class of analytical tool, is particularly interesting taking into account its numerous advantages such as fast data acquisition and no sample preparation. In this context, near-infrared, Raman and mainly surface-enhanced Raman spectroscopy (SERS) have thus gained interest in many fields including bioanalysis. The two former techniques only ensure the analysis of concentrated compounds in simple matrices, whereas the emergence of SERS improved the performances of vibrational spectroscopy to very sensitive and selective analyses. Complex SERS substrates were also developed enabling biomarker measurements, paving the way for SERS immunoassays. Therefore, in this paper, the strengths and weaknesses of these techniques will be highlighted with a focus on recent progress.

Synthetic biology meets tissue engineering.

PubMed

Davies, Jamie A; Cachat, Elise

2016-06-15

Classical tissue engineering is aimed mainly at producing anatomically and physiologically realistic replacements for normal human tissues. It is done either by encouraging cellular colonization of manufactured matrices or cellular recolonization of decellularized natural extracellular matrices from donor organs, or by allowing cells to self-organize into organs as they do during fetal life. For repair of normal bodies, this will be adequate but there are reasons for making unusual, non-evolved tissues (repair of unusual bodies, interface to electromechanical prostheses, incorporating living cells into life-support machines). Synthetic biology is aimed mainly at engineering cells so that they can perform custom functions: applying synthetic biological approaches to tissue engineering may be one way of engineering custom structures. In this article, we outline the 'embryological cycle' of patterning, differentiation and morphogenesis and review progress that has been made in constructing synthetic biological systems to reproduce these processes in new ways. The state-of-the-art remains a long way from making truly synthetic tissues, but there are now at least foundations for future work. © 2016 Authors; published by Portland Press Limited.

Progress and development of analytical methods for gibberellins.

PubMed

Pan, Chaozhi; Tan, Swee Ngin; Yong, Jean Wan Hong; Ge, Liya

2017-01-01

Gibberellins, as a group of phytohormones, exhibit a wide variety of bio-functions within plant growth and development, which have been used to increase crop yields. Many analytical procedures, therefore, have been developed for the determination of the types and levels of endogenous and exogenous gibberellins. As plant tissues contain gibberellins in trace amounts (usually at the level of nanogram per gram fresh weight or even lower), the sample pre-treatment steps (extraction, pre-concentration, and purification) for gibberellins are reviewed in details. The primary focus of this comprehensive review is on the various analytical methods designed to meet the requirements for gibberellins analyses in complex matrices with particular emphasis on high-throughput analytical methods, such as gas chromatography, liquid chromatography, and capillary electrophoresis, mostly combined with mass spectrometry. The advantages and drawbacks of the each described analytical method are discussed. The overall aim of this review is to provide a comprehensive and critical view on the different analytical methods nowadays employed to analyze gibberellins in complex sample matrices and their foreseeable trends. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Methods of Analysis by the U.S. Geological Survey Organic Geochemistry Research Group-Determination of Dissolved Isoxaflutole and Its Sequential Degradation Products, Diketonitrile and Benzoic Acid, in Water Using Solid-Phase Extraction and Liquid Chromatography/Tandem Mass Spectrometry

USGS Publications Warehouse

Meyer, Michael T.; Lee, Edward A.; Scribner, Elisabeth A.

2007-01-01

An analytical method for the determination of isoxaflutole and its sequential degradation products, diketonitrile and a benzoic acid analogue, in filtered water with varying matrices was developed by the U.S. Geological Survey Organic Geochemistry Research Group in Lawrence, Kansas. Four different water-sample matrices fortified at 0.02 and 0.10 ug/L (micrograms per liter) are extracted by vacuum manifold solid-phase extraction and analyzed by liquid chromatography/tandem mass spectrometry using electrospray ionization in negative-ion mode with multiple-reaction monitoring (MRM). Analytical conditions for mass spectrometry detection are optimized, and quantitation is carried out using the following MRM molecular-hydrogen (precursor) ion and product (p) ion transition pairs: 357.9 (precursor), 78.9 (p), and 277.6 (p) for isoxaflutole and diketonitrile, and 267.0 (precursor), 159.0 (p), and 223.1 (p) for benzoic acid. 2,4-dichlorophenoxyacetic acid-d3 is used as the internal standard, and alachlor ethanesulfonic acid-d5 is used as the surrogate standard. Compound detection limits and reporting levels are calculated using U.S. Environmental Protection Agency procedures. The mean solid-phase extraction recovery values ranged from 104 to 108 percent with relative standard deviation percentages ranging from 4.0 to 10.6 percent. The combined mean percentage concentration normalized to the theoretical spiked concentration of four water matrices analyzed eight times at 0.02 and 0.10 ug/L (seven times for the reagent-water matrix at 0.02 ug/L) ranged from approximately 75 to 101 percent with relative standard deviation percentages ranging from approximately 3 to 26 percent for isoxaflutole, diketonitrile, and benzoic acid. The method detection limit (MDL) for isoxaflutole and diketonitrile is 0.003 ug/L and 0.004 ug/L for benzoic acid. Method reporting levels (MRLs) are 0.011, 0.010, and 0.012 ug/L for isoxaflutole, diketonitrile, and benzoic acid, respectively. On the basis of the calculated MRLs and MDLs and evaluation of the signal-to-noise ratios for each compound, the MRLs and MDLs are set at 0.010 and 0.003 ug/L, respectively, for all three compounds.

34 CFR 106.43 - Standards for measuring skill or progress in physical education classes.

Code of Federal Regulations, 2011 CFR

2011-07-01

... PROGRAMS OR ACTIVITIES RECEIVING FEDERAL FINANCIAL ASSISTANCE Discrimination on the Basis of Sex in Education Programs or Activities Prohibited § 106.43 Standards for measuring skill or progress in physical... 34 Education 1 2011-07-01 2011-07-01 false Standards for measuring skill or progress in physical...

34 CFR 106.43 - Standards for measuring skill or progress in physical education classes.

Code of Federal Regulations, 2014 CFR

2014-07-01

... PROGRAMS OR ACTIVITIES RECEIVING FEDERAL FINANCIAL ASSISTANCE Discrimination on the Basis of Sex in Education Programs or Activities Prohibited § 106.43 Standards for measuring skill or progress in physical... 34 Education 1 2014-07-01 2014-07-01 false Standards for measuring skill or progress in physical...

34 CFR 106.43 - Standards for measuring skill or progress in physical education classes.

Code of Federal Regulations, 2012 CFR

2012-07-01

... PROGRAMS OR ACTIVITIES RECEIVING FEDERAL FINANCIAL ASSISTANCE Discrimination on the Basis of Sex in Education Programs or Activities Prohibited § 106.43 Standards for measuring skill or progress in physical... 34 Education 1 2012-07-01 2012-07-01 false Standards for measuring skill or progress in physical...

34 CFR 106.43 - Standards for measuring skill or progress in physical education classes.

Code of Federal Regulations, 2013 CFR

2013-07-01

... PROGRAMS OR ACTIVITIES RECEIVING FEDERAL FINANCIAL ASSISTANCE Discrimination on the Basis of Sex in Education Programs or Activities Prohibited § 106.43 Standards for measuring skill or progress in physical... 34 Education 1 2013-07-01 2013-07-01 false Standards for measuring skill or progress in physical...

Influence of prenatal and postnatal growth on intellectual functioning in school-aged children.

PubMed

Pongcharoen, Tippawan; Ramakrishnan, Usha; DiGirolamo, Ann M; Winichagoon, Pattanee; Flores, Rafael; Singkhornard, Jintana; Martorell, Reynaldo

2012-05-01

To assess the relative influence of size at birth, infant growth, and late postnatal growth on intellectual functioning at 9 years of age. A follow-up, cross-sectional study. Three districts in Khon Kaen province, northeast Thailand. A total of 560 children, or 92% of former participants of a trial of iron and/or zinc supplementation during infancy. Prenatal (size at birth), early infancy (birth to 4 months), late infancy (4 months to 1 year), and late postnatal (1 to 9 years) growth. Multiple-stage least squares analyses were used to generate uncorrelated residuals of postnatal growth. Intellectual functioning was measured at 9 years using the Wechsler Intelligence Scale for Children and the Raven's Colored Progressive Matrices (Pearson). Analyses included adjustment for maternal, household, and school characteristics. Significant relationships were found between growth and IQ (Wechsler Intelligence Scale for children, third edition, Thai version), but only up to 1 year of age; overall, growth was not related to the Raven's Colored Progressive Matrices. The strongest and most consistent relationships were with length (birth, early infancy, and late infancy); for weight, only early infancy gain was consistently related to IQ. Head circumference at birth was not collected routinely; head circumference at 4 months (but not head circumference growth thereafter) was related to IQ. Late postnatal growth was not associated with any outcome. Physical growth in early infancy (and, to a lesser extent, physical growth in late infancy and at birth) is associated with IQ at 9 years of age. Early infancy may be a critical window for human development.

Development and application of a high-throughput sample cleanup process based on 96-well plate for simultaneous determination of 16 steroids in biological matrices using liquid chromatography-triple quadrupole mass spectrometry.

PubMed

Luo, Guanzhong; Li, Youxin; Bao, James J

2016-02-01

A novel high-throughput sample pretreatment system was developed by the integration of protein precipitation (PP), phospholipid removal (PPR), and hollow fiber liquid-phase microextraction (HF-LPME) into two simple 96-well plates and a matching 96-grid lid. With this system, 16 steroids were separated from biological matrices of plasma, milk, and urine and analyzed by liquid chromatography-triple quadrupole mass spectrometry. In the tandem sample cleanup process, the prepositive PP and PPR step preliminarily removed some of the interferences from the biological matrices. The following HF-LPME step kept the residual interference out of the hollow fiber and enriched the steroids in the hollow fiber to achieve high sensitivity. By a series of method optimizations, acetonitrile was chosen as the crash solvent for PP and PPR. A mixture of octanol and toluene (1:1 v/v) was used as the acceptor phase for HF-LPME. The extraction was conducted at 80 rpm for 50 min in a donor phase containing 1 mL 20% sodium chloride at 25 °C. Under these conditions, the limits of detection for the 16 steroids were 3.6-300.0 pg(.)mL(-1) in plasma, 3.0-270.0 pg·mL(-1) in milk, and 2.2-210.0 pg(.)mL(-1) in urine. The recoveries of the 16 steroids were 81.9-97.9% in plasma (relative standard deviation 1.0-8.0%), 80.6-97.7% in milk (relative standard deviation 0.8-5.4%), and 87.3-98.7% in urine (relative standard deviation 1.0-4.9%). Further, the integrated 96-well platform of PP, PPR, and HF-LPME enabled us to run this assay in an automatic and high-throughput fashion. The reliability of the method was further corroborated by evaluation of its applicability in plasma and urine samples from volunteers and fresh bovine milk from local dairy enterprises.

Determination of synthetic ferric chelates used as fertilizers by liquid chromatography-electrospray/mass spectrometry in agricultural matrices.

PubMed

Alvarez-Fernández, Ana; Orera, Irene; Abadía, Javier; Abadía, Anunciación

2007-01-01

A high-performance liquid chromatography-electrospray ionization/mass spectrometry (time of flight) method has been developed for the simultaneous determination of synthetic Fe(III)-chelates used as fertilizers. Analytes included the seven major Fe(III)-chelates used in agriculture, Fe(III)-EDTA, Fe(III)-DTPA, Fe(III)-HEDTA, Fe(III)-CDTA, Fe(III)-o,oEDDHA, Fe(III)-o,pEDDHA, and Fe(III)-EDDHMA, and the method was validated using isotope labeled (57)Fe(III)-chelates as internal standards. Calibration curves had R values in the range 0.9962-0.9997. Limits of detection and quantification were in the ranges 3-164 and 14-945 pmol, respectively. Analyte concentrations could be determined between the limits of quantification and 25 muM (racemic and meso Fe(III)-o,oEDDHA and Fe(III)-EDDHMA) or 50 muM (Fe(III)-EDTA, Fe(III)-HEDTA, Fe(III)-DTPA, Fe(III)-CDTA and Fe(III)-o,pEDDHA). The average intraday repeatability values were approximately 0.5 and 5% for retention time and peak area, respectively, whereas the interday repeatability values were approximately 0.7 and 8% for retention time and peak area, respectively. The method was validated using four different agricultural matrices, including nutrient solution, irrigation water, soil solution, and plant xylem exudates, spiked with Fe(III)-chelate standards and their stable isotope-labeled corresponding chelates. Analyte recoveries found were in the ranges 92-101% (nutrient solution), 89-102% (irrigation water), 82-100% (soil solution), and 70-111% (plant xylem exudates). Recoveries depended on the analyte, with Fe(III)-EDTA and Fe(III)-DTPA showing the lowest recoveries (average values of 87 and 88%, respectively, for all agricultural matrices used), whereas for other analytes recoveries were between 91 and 101%. The method was also used to determine the real concentrations of Fe(III)-chelates in commercial fertilizers. Furthermore, the method is also capable of resolving two more synthetic Fe(III)-chelates, Fe(III)-EDDHSA and Fe(III)-EDDCHA, whose exact quantification is not currently possible because of lack of commercial standards.

Application of p-Multigrid to Discontinuous Galerkin Formulations of the Poisson Equation

NASA Technical Reports Server (NTRS)

Helenbrook, B. T.; Atkins, H. L.

2006-01-01

We investigate p-multigrid as a solution method for several different discontinuous Galerkin (DG) formulations of the Poisson equation. Different combinations of relaxation schemes and basis sets have been combined with the DG formulations to find the best performing combination. The damping factors of the schemes have been determined using Fourier analysis for both one and two-dimensional problems. One important finding is that when using DG formulations, the standard approach of forming the coarse p matrices separately for each level of multigrid is often unstable. To ensure stability the coarse p matrices must be constructed from the fine grid matrices using algebraic multigrid techniques. Of the relaxation schemes, we find that the combination of Jacobi relaxation with the spectral element basis is fairly effective. The results using this combination are p sensitive in both one and two dimensions, but reasonable convergence rates can still be achieved for moderate values of p and isotropic meshes. A competitive alternative is a block Gauss-Seidel relaxation. This actually out performs a more expensive line relaxation when the mesh is isotropic. When the mesh becomes highly anisotropic, the implicit line method and the Gauss-Seidel implicit line method are the only effective schemes. Adding the Gauss-Seidel terms to the implicit line method gives a significant improvement over the line relaxation method.

Determination of tributyltin in environmental water matrices using stir bar sorptive extraction with in-situ derivatisation and large volume injection-gas chromatography-mass spectrometry.

PubMed

Neng, N R; Santalla, R P; Nogueira, J M F

2014-08-01

Stir bar sorptive extraction with in-situ derivatization using sodium tetrahydridoborate (NaBH4) followed by liquid desorption and large volume injection-gas chromatography-mass spectrometry detection under the selected ion monitoring mode (SBSE(NaBH4)in-situ-LD/LVI-GC-MS(SIM)) was successfully developed for the determination of tributyltin (TBT) in environmental water matrices. NaBH4 proved to be an effective and easy in-situ speciation agent for TBT in aqueous media, allowing the formation of adducts with enough stability and suitable polarity for SBSE analysis. Assays performed on water samples spiked at the 10.0μg/L, yielded convenient recoveries (68.2±3.0%), showed good accuracy, suitable precision (RSD<9.0%), low detection limits (23ng/L) and excellent linear dynamic range (r(2)=0.9999) from 0.1 to 170.0µg/L, under optimized experimental conditions. By using the standard addition method, the application of the present methodology to real surface water samples allowed very good performance at the trace level. The proposed methodology proved to be a feasible alternative for routine quality control analysis, easy to implement, reliable and sensitive to monitor TBT in environmental water matrices. Copyright © 2014 Elsevier B.V. All rights reserved.

Evaluation of different derivatisation approaches for gas chromatographic-mass spectrometric analysis of carbohydrates in complex matrices of biological and synthetic origin.

PubMed

Becker, M; Zweckmair, T; Forneck, A; Rosenau, T; Potthast, A; Liebner, F

2013-03-15

Gas chromatographic analysis of complex carbohydrate mixtures requires highly effective and reliable derivatisation strategies for successful separation, identification, and quantitation of all constituents. Different single-step (per-trimethylsilylation, isopropylidenation) and two-step approaches (ethoximation-trimethylsilylation, ethoximation-trifluoroacetylation, benzoximation-trimethylsilylation, benzoximation-trifluoroacetylation) have been comprehensively studied with regard to chromatographic characteristics, informational value of mass spectra, ease of peak assignment, robustness toward matrix effects, and quantitation using a set of reference compounds that comprise eight monosaccharides (C(5)-C(6)), glycolaldehyde, and dihydroxyacetone. It has been shown that isopropylidenation and the two oximation-trifluoroacetylation approaches are least suitable for complex carbohydrate matrices. Whereas the former is limited to compounds that contain vicinal dihydroxy moieties in cis configuration, the latter two methods are sensitive to traces of trifluoroacetic acid which strongly supports decomposition of ketohexoses. It has been demonstrated for two "real" carbohydrate-rich matrices of biological and synthetic origin, respectively, that two-step ethoximation-trimethylsilylation is superior to other approaches due to the low number of peaks obtained per carbohydrate, good peak separation performance, structural information of mass spectra, low limits of detection and quantitation, minor relative standard deviations, and low sensitivity toward matrix effects. Copyright © 2013 Elsevier B.V. All rights reserved.

Combining bar adsorptive microextraction with capillary electrophoresis--application for the determination of phenolic acids in food matrices.

PubMed

da Rosa Neng, Nuno; Sequeiros, Rute C P; Florêncio Nogueira, José Manuel

2014-09-01

In this contribution, bar adsorptive microextraction coated with a mixed-mode anion exchange/RP followed by liquid desorption was combined for the first time with a capillary electrophoresis-diode array detection system (BAμE(MAX)-LD/CE-DAD), for the determination of phenolic acids in food matrices, using chlorogenic, ferulic, cumaric, and caffeic acids as model compounds. Assays performed in aqueous media spiked at the 0.8 mg/L level yielded average recoveries up to 40% for all four phenolic acids, under optimized experimental conditions. The analytical performance showed also good precision (RSD < 15%), convenient LODs (18.0-85.0 μg/L) and linear dynamic ranges (0.8-8.0 mg/L) with convenient determination coefficients (r(2) > 0.9900). By using the standard addition method, the application to food matrices such as green tea, red fruit juice, and honey allowed very good performances for the determination of minor amounts of phenolic acids. The proposed methodology proved to be a suitable alternative for the analysis of polar to ionic compounds, showing to be easy to implement, reliable, sensitive, and requiring a low sample volume to determine phenolic acids in food samples. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Estimation of premorbid general fluid intelligence using traditional Chinese reading performance in Taiwanese samples.

PubMed

Chen, Ying-Jen; Ho, Meng-Yang; Chen, Kwan-Ju; Hsu, Chia-Fen; Ryu, Shan-Jin

2009-08-01

The aims of the present study were to (i) investigate if traditional Chinese word reading ability can be used for estimating premorbid general intelligence; and (ii) to provide multiple regression equations for estimating premorbid performance on Raven's Standard Progressive Matrices (RSPM), using age, years of education and Chinese Graded Word Reading Test (CGWRT) scores as predictor variables. Four hundred and twenty-six healthy volunteers (201 male, 225 female), aged 16-93 years (mean +/- SD, 41.92 +/- 18.19 years) undertook the tests individually under supervised conditions. Seventy percent of subjects were randomly allocated to the derivation group (n = 296), and the rest to the validation group (n = 130). RSPM score was positively correlated with CGWRT score and years of education. RSPM and CGWRT scores and years of education were also inversely correlated with age, but the declining trend for RSPM performance against age was steeper than that for CGWRT performance. Separate multiple regression equations were derived for estimating RSPM scores using different combinations of age, years of education, and CGWRT score for both groups. The multiple regression coefficient of each equation ranged from 0.71 to 0.80 with the standard error of estimate between 7 and 8 RSPM points. When fitting the data of one group to the equations derived from its counterpart group, the cross-validation multiple regression coefficients ranged from 0.71 to 0.79. There were no significant differences in the 'predicted-obtained' RSPM discrepancies between any equations. The regression equations derived in the present study may provide a basis for estimating premorbid RSPM performance.

Excitation-emission matrix fluorescence spectroscopy in conjunction with multiway analysis for PAH detection in complex matrices.

PubMed

Nahorniak, Michelle L; Booksh, Karl S

2006-12-01

A field portable, single exposure excitation-emission matrix (EEM) fluorometer has been constructed and used in conjunction with parallel factor analysis (PARAFAC) to determine the sub part per billion (ppb) concentrations of several aqueous polycyclic aromatic hydrocarbons (PAHs), such as benzo(k)fluoranthene and benzo(a)pyrene, in various matrices including aqueous motor oil extract and asphalt leachate. Multiway methods like PARAFAC are essential to resolve the analyte signature from the ubiquitous background in environmental samples. With multiway data and PARAFAC analysis it is shown that reliable concentration determinations can be achieved with minimal standards in spite of the large convoluting fluorescence background signal. Thus, rapid fieldable EEM analyses may prove to be a good screening method for tracking pollutants and prioritizing sampling and analysis by more complete but time consuming and labor intensive EPA methods.

Derivation of an eigenvalue probability density function relating to the Poincaré disk

NASA Astrophysics Data System (ADS)

Forrester, Peter J.; Krishnapur, Manjunath

2009-09-01

A result of Zyczkowski and Sommers (2000 J. Phys. A: Math. Gen. 33 2045-57) gives the eigenvalue probability density function for the top N × N sub-block of a Haar distributed matrix from U(N + n). In the case n >= N, we rederive this result, starting from knowledge of the distribution of the sub-blocks, introducing the Schur decomposition and integrating over all variables except the eigenvalues. The integration is done by identifying a recursive structure which reduces the dimension. This approach is inspired by an analogous approach which has been recently applied to determine the eigenvalue probability density function for random matrices A-1B, where A and B are random matrices with entries standard complex normals. We relate the eigenvalue distribution of the sub-blocks to a many-body quantum state, and to the one-component plasma, on the pseudosphere.

Electron microprobe mineral analysis guide

NASA Technical Reports Server (NTRS)

Brown, R. W.

1980-01-01

Electron microprobe mineral analysis guide is a compilation of X-ray tables and spectra recorded from various mineral matrices. Spectra were obtained using electron microprobe, equipped with LiF geared, curved crystal X-ray spectrometers, utilizing typical analytical operating conditions: 15 Kv acceleration potential, 0.02 microampere sample current as measured on a clinopyroxene standard (CP19). Tables and spectra are presented for the majority of elements, fluorine through uranium, occurring in mineral samples from lunar, meteoritic and terrestrial sources. Tables for each element contain relevant analytical information, i.e., analyzing crystal, X-ray peak, background and relative intensity information, X-ray interferences and a section containing notes on the measurement. Originally intended to cover silicates and oxide minerals the tables and spectra have been expanded to cover other mineral phases. Electron microprobe mineral analysis guide is intended as a spectral base to which additional spectra can be added as the analyst encounters new mineral matrices.

Limonene encapsulation in freeze dried gellan systems.

PubMed

Evageliou, Vasiliki; Saliari, Dimitra

2017-05-15

The encapsulation of limonene in freeze-dried gellan systems was investigated. Surface and encapsulated limonene content was determined by measurement of the absorbance at 252nm. Gellan matrices were both gels and solutions. For a standard gellan concentration (0.5wt%) gelation was induced by potassium or calcium chloride. Furthermore, gellan solutions of varying concentrations (0.25-1wt%) were also studied. Limonene was added at two different concentrations (1 and 2mL/100g sample). Gellan gels encapsulated greater amounts of limonene than solutions. Among all gellan gels, the KCl gels had the greater encapsulated limonene content. However, when the concentration of limonene was doubled in these KCl gels, the encapsulated limonene decreased. The surface limonene content was significant, especially for gellan solutions. The experimental conditions and not the mechanical properties of the matrices were the dominant factor in the interpretation of the observed results. Copyright © 2016 Elsevier Ltd. All rights reserved.

DCTune Perceptual Optimization of Compressed Dental X-Rays

NASA Technical Reports Server (NTRS)

Watson, Andrew B.; Null, Cynthia H. (Technical Monitor)

1997-01-01

In current dental practice, x-rays of completed dental work are often sent to the insurer for verification. It is faster and cheaper to transmit instead digital scans of the x-rays. Further economies result if the images are sent in compressed form. DCtune is a technology for optimizing DCT quantization matrices to yield maximum perceptual quality for a given bit-rate, or minimum bit-rate for a given perceptual quality. In addition, the technology provides a means of setting the perceptual quality of compressed imagery in a systematic way. The purpose of this research was, with respect to dental x-rays: (1) to verify the advantage of DCTune over standard JPEG; (2) to verify the quality control feature of DCTune; and (3) to discover regularities in the optimized matrices of a set of images. Additional information is contained in the original extended abstract.

Clinical applications of decellularized extracellular matrices for tissue engineering and regenerative medicine.

PubMed

Parmaksiz, Mahmut; Dogan, Arin; Odabas, Sedat; Elçin, A Eser; Elçin, Y Murat

2016-03-17

Decellularization is the process of removing the cellular components from tissues or organs. It is a promising technology for obtaining a biomaterial with a highly preserved extracellular matrix (ECM), which may also act as a biological scaffold for tissue engineering and regenerative therapies. Decellularized products are gaining clinical importance and market space due to their ease of standardized production, constant availability for grafting and mechanical or biochemical superiority against competing clinical options, yielding clinical results ahead of the ones with autografts in some applications. Current drawbacks and limitations of traditional treatments and clinical applications can be overcome by using decellularized or acellular matrices. Several companies are leading the market with versatile acellular products designed for diverse use in the reconstruction of tissues and organs. This review describes ECM-based decellularized and acellular products that are currently in use for different branches of clinic.

Dwell time-based stabilisation of switched delay systems using free-weighting matrices

NASA Astrophysics Data System (ADS)

Koru, Ahmet Taha; Delibaşı, Akın; Özbay, Hitay

2018-01-01

In this paper, we present a quasi-convex optimisation method to minimise an upper bound of the dwell time for stability of switched delay systems. Piecewise Lyapunov-Krasovskii functionals are introduced and the upper bound for the derivative of Lyapunov functionals is estimated by free-weighting matrices method to investigate non-switching stability of each candidate subsystems. Then, a sufficient condition for the dwell time is derived to guarantee the asymptotic stability of the switched delay system. Once these conditions are represented by a set of linear matrix inequalities , dwell time optimisation problem can be formulated as a standard quasi-convex optimisation problem. Numerical examples are given to illustrate the improvements over previously obtained dwell time bounds. Using the results obtained in the stability case, we present a nonlinear minimisation algorithm to synthesise the dwell time minimiser controllers. The algorithm solves the problem with successive linearisation of nonlinear conditions.

Selective identification and quantification of saccharin by liquid chromatography and fluorescence detection.

PubMed

Bruno, Sergio N F; Cardoso, Carlos R; Maciel, Márcia Mosca A; Vokac, Lidmila; da Silva Junior, Ademário I

2014-09-15

High-pressure liquid chromatography with ultra-violet detection (HPLC-UV) is one of the most commonly used methods to identify and quantify saccharin in non-alcoholic beverages. However, due to the wide variety of interfering UV spectra in saccharin-containing beverage matrices, the same method cannot be used to measure this analyte accurately. We have developed a new, highly effective method to identify and quantify saccharin using HPLC with fluorescence detection (HPLC-FLD). The excitation wavelength (250 nm) and emission wavelength (440 nm) chosen increased selectivity for all matrices and ensured few changes were required in the mobile phase or other parameters. The presence of saccharin in non-diet beverages - a fraud commonly used to replace more expensive sucrose - was confirmed by comparing coincident peaks as well as the emission spectra of standards and samples. Copyright © 2014 Elsevier Ltd. All rights reserved.

Green-noise halftoning with dot diffusion

NASA Astrophysics Data System (ADS)

Lippens, Stefaan; Philips, Wilfried

2007-02-01

Dot diffusion is a halftoning technique that is based on the traditional error diffusion concept, but offers a high degree of parallel processing by its block based approach. Traditional dot diffusion however suffers from periodicity artifacts. To limit the visibility of these artifacts, we propose grid diffusion, which applies different class matrices for different blocks. Furthermore, in this paper we will discuss two approaches in the dot diffusion framework to generate green-noise halftone patterns. The first approach is based on output dependent feedback (hysteresis), analogous to the standard green-noise error diffusion techniques. We observe that the resulting halftones are rather coarse and highly dependent on the used dot diffusion class matrices. In the second approach we don't limit the diffusion to the nearest neighbors. This leads to less coarse halftones, compared to the first approach. The drawback is that it can only cope with rather limited cluster sizes. We can reduce these drawbacks by combining the two approaches.

Lack of robustness of textural measures obtained from 3D brain tumor MRIs impose a need for standardization

PubMed Central

Pérez-Beteta, Julián; Martínez-González, Alicia; Martino, Juan; Velasquez, Carlos; Arana, Estanislao; Pérez-García, Víctor M.

2017-01-01

Purpose Textural measures have been widely explored as imaging biomarkers in cancer. However, their robustness under dynamic range and spatial resolution changes in brain 3D magnetic resonance images (MRI) has not been assessed. The aim of this work was to study potential variations of textural measures due to changes in MRI protocols. Materials and methods Twenty patients harboring glioblastoma with pretreatment 3D T1-weighted MRIs were included in the study. Four different spatial resolution combinations and three dynamic ranges were studied for each patient. Sixteen three-dimensional textural heterogeneity measures were computed for each patient and configuration including co-occurrence matrices (CM) features and run-length matrices (RLM) features. The coefficient of variation was used to assess the robustness of the measures in two series of experiments corresponding to (i) changing the dynamic range and (ii) changing the matrix size. Results No textural measures were robust under dynamic range changes. Entropy was the only textural feature robust under spatial resolution changes (coefficient of variation under 10% in all cases). Conclusion Textural measures of three-dimensional brain tumor images are not robust neither under dynamic range nor under matrix size changes. Standards should be harmonized to use textural features as imaging biomarkers in radiomic-based studies. The implications of this work go beyond the specific tumor type studied here and pose the need for standardization in textural feature calculation of oncological images. PMID:28586353

Evaluation of stir-bar sorptive extraction coupled with thermal desorption GC-MS for the detection of leachables from polymer single use systems to drugs.

PubMed

Scherer, Nicole; Marcseková, Klaudia; Posset, Tobias; Winter, Gerhard

2018-04-15

Stir-bar Sorptive Extraction (SBSE) in combination with thermal desorption and gas chromatography-mass spectrometry (TD-GC-MS) is widely accepted as the gold-standard analysis method for trace amounts of organic substances, including leachables in aqueous matrices. Meanwhile, as far as pharmaceutical quality control in protein-based parenteral drugs is concerned, the use of SBSE analysis remains unexplored. Previous studies reported a strong influence of the matrix on the method's recovery. The scope of the present work was to fill in the unexplored territory in a threefold manner 1) by quantifying the effects that various matrices commonly found in pharmaceutical processing have on the recovery, 2) by comparing between different coating materials for stir bar (namely between polydimethylsiloxane (PDMS) material and ethylene-glycol (EG)-PDMS), and 3) by proposing a preparation step for stir-bar to mitigate inhibitory effects. The current study shows no inhibition of SBSE by protein matrices (p > 0.15). Further the influence of various drug matrices on the recovery of leachables with a log K o/w  ≥ 3.6 is negligible (-3.9 to 3.8%). In contrast, the inhibition effect caused by an alkaline media led to a recovery decrease of -42.9%. For leachables with a log K o/w  < 3.6, the relative recovery in the presence of various proteins ranged from -72.8% to 15.6%, depending on the excipients of the drug product and not on the protein itself. The highest loss in sensitivity was observed when the excipient benzyl alcohol was present in the drug. Nonetheless, the limit of detection for the tested leachables in the inhibitory matrices was still below 3 μg/L (ppb). Additionally, SBSE was observed to be quantitatively reliable in all tested drug matrices for concentrations from 0.005 to 0.1 mg/mL (r 2  > 0.992). On average, the conventional PDMS coating resulted in a 28-fold higher signal-to-noise ratio compared to EG-PDMS. Furthermore, a broader range of leachables was detectable with the PDSM coating. Preceding stir-bar preparation consisting of a simple soaking step improved the enrichment by 14%, effectively lowering the limit of detection. Copyright © 2018 Elsevier B.V. All rights reserved.

Fortified Iodine Milk Improves Iodine Status and Cognitive Abilities in Schoolchildren Aged 7-9 Years Living in a Rural Mountainous Area of Morocco.

PubMed

Zahrou, Fatima Ezzahra; Azlaf, Mehdi; El Menchawy, Imane; El Mzibri, Mohamed; El Kari, Khalid; El Hamdouchi, Asmaa; Mouzouni, Fatima-Zahra; Barkat, Amina; Aguenaou, Hassan

2016-01-01

Iodine is required for the production of the thyroid hormones essential for the growth and development of the brain. All forms of iodine deficiency (ID) affect the mental development of the child. Our study aims to assess the impact of ID on the intellectual development of Moroccan schoolchildren and to evaluate the effect of consumption of fortified milk on reducing ID. In a double-blind controlled trial conducted on schoolchildren, children were divided into two groups to receive fortified milk (30% of cover of RDI iodine) or nonfortified milk for 9 months. Urinary iodine was analyzed using the Sandell-Kolthoff reaction, a dynamic cognitive test using Raven's Standard Progressive Matrices to assess learning potential was performed at baseline and end line, and anthropometric assessment was done only at baseline. The study included schoolchildren who were severely iodine deficient. The prevalence of malnutrition was high in both groups; in this study, we found improvements in iodine status and in cognitive abilities among Moroccan schoolchildren. Our study showed that the consumption of fortified milk led to a clear improvement in iodine status and also appeared to have a favorable effect on the cognitive ability of Moroccan schoolchildren in a rural mountainous region.

CMV matrices in random matrix theory and integrable systems: a survey

NASA Astrophysics Data System (ADS)

Nenciu, Irina

2006-07-01

We present a survey of recent results concerning a remarkable class of unitary matrices, the CMV matrices. We are particularly interested in the role they play in the theory of random matrices and integrable systems. Throughout the paper we also emphasize the analogies and connections to Jacobi matrices.

Basal Cell Carcinoma With Matrical Differentiation: Clinicopathologic, Immunohistochemical, and Molecular Biological Study of 22 Cases.

PubMed

Kyrpychova, Liubov; Carr, Richard A; Martinek, Petr; Vanecek, Tomas; Perret, Raul; Chottová-Dvořáková, Magdalena; Zamecnik, Michal; Hadravsky, Ladislav; Michal, Michal; Kazakov, Dmitry V

2017-06-01

Basal cell carcinoma (BCC) with matrical differentiation is a fairly rare neoplasm, with about 30 cases documented mainly as isolated case reports. We studied a series of this neoplasm, including cases with an atypical matrical component, a hitherto unreported feature. Lesions coded as BCC with matrical differentiation were reviewed; 22 cases were included. Immunohistochemical studies were performed using antibodies against BerEp4, β-catenin, and epithelial membrane antigen (EMA). Molecular genetic studies using Ion AmpliSeq Cancer Hotspot Panel v2 by massively parallel sequencing on Ion Torrent PGM were performed in 2 cases with an atypical matrical component (1 was previously subjected to microdissection to sample the matrical and BCC areas separately). There were 13 male and 9 female patients, ranging in age from 41 to 89 years. Microscopically, all lesions manifested at least 2 components, a BCC area (follicular germinative differentiation) and areas with matrical differentiation. A BCC component dominated in 14 cases, whereas a matrical component dominated in 4 cases. Matrical differentiation was recognized as matrical/supramatrical cells (n=21), shadow cells (n=21), bright red trichohyaline granules (n=18), and blue-gray corneocytes (n=18). In 2 cases, matrical areas manifested cytologic atypia, and a third case exhibited an infiltrative growth pattern, with the tumor metastasizing to a lymph node. BerEP4 labeled the follicular germinative cells, whereas it was markedly reduced or negative in matrical areas. The reverse pattern was seen with β-catenin. EMA was negative in BCC areas but stained a proportion of matrical/supramatrical cells. Genetic studies revealed mutations of the following genes: CTNNB1, KIT, CDKN2A, TP53, SMAD4, ERBB4, and PTCH1, with some differences between the matrical and BCC components. It is concluded that matrical differentiation in BCC in most cases occurs as multiple foci. Rare neoplasms manifest atypia in the matrical areas. Immunohistochemical analysis for BerEP4, EMA, and β-catenin can be helpful in limited biopsy specimens. From a molecular biological prospective, BCC and matrical components appear to share some of the gene mutations but have differences in others, but this observation must be validated in a large series.

Magnetic resonance microscopy for assessment of morphological changes in hydrating hydroxypropylmethylcellulose matrix tablets in situ-is it possible to detect phenomena related to drug dissolution within the hydrated matrices?

PubMed

Kulinowski, Piotr; Młynarczyk, Anna; Jasiński, Krzysztof; Talik, Przemysław; Gruwel, Marco L H; Tomanek, Bogusław; Węglarz, Władysław P; Dorożyński, Przemysław

2014-09-01

So far, the hydrated part of the HPMC matrix has commonly been denoted as a "gel" or "pseudogel" layer. No MRI-based results have been published regarding observation of internal phenomena related to drug dissolution inside swelling polymeric matrices during hydration. The purpose of the study was to detect such phenomena. Multiparametric, spatially and temporally resolved T2 MR relaxometry, in situ, was applied to study formation of the hydration progress in HPMC matrix tablets loaded with L-dopa and ketoprofen using a 11.7 T MRI system. Two spin-echo based pulse sequences were used, one of them specifically designed to study short T2 signals. Two components in the T2 decay envelope were estimated and spatial distributions of their parameters, i.e. amplitudes and T2 values, were obtained. Based on the data, different region formation patterns (i.e. multilayer structure) were registered depending on drug presence and solubility. Inside the matrix with incorporated sparingly soluble drug a specific layer formation due to drug dissolution was detected, whereas a matrix with very slightly soluble drug does not form distinct external "gel-like" layer. We have introduced a new paradigm in the characterization of hydrating matrices using (1)H MRI methods. It reflects molecular mobility and concentration of water inside the hydrated matrix. For the first time, drug dissolution related phenomena, i.e. particular front and region formation, were observed by MRI methods.

An isotope-dilution standard GC/MS/MS method for steroid hormones in water

USGS Publications Warehouse

Foreman, William T.; Gray, James L.; ReVello, Rhiannon C.; Lindley, Chris E.; Losche, Scott A.

2013-01-01

An isotope-dilution quantification method was developed for 20 natural and synthetic steroid hormones and additional compounds in filtered and unfiltered water. Deuterium- or carbon-13-labeled isotope-dilution standards (IDSs) are added to the water sample, which is passed through an octadecylsilyl solid-phase extraction (SPE) disk. Following extract cleanup using Florisil SPE, method compounds are converted to trimethylsilyl derivatives and analyzed by gas chromatography with tandem mass spectrometry. Validation matrices included reagent water, wastewater-affected surface water, and primary (no biological treatment) and secondary wastewater effluent. Overall method recovery for all analytes in these matrices averaged 100%; with overall relative standard deviation of 28%. Mean recoveries of the 20 individual analytes for spiked reagent-water samples prepared along with field samples analyzed in 2009–2010 ranged from 84–104%, with relative standard deviations of 6–36%. Detection levels estimated using ASTM International’s D6091–07 procedure range from 0.4 to 4 ng/L for 17 analytes. Higher censoring levels of 100 ng/L for bisphenol A and 200 ng/L for cholesterol and 3-beta-coprostanol are used to prevent bias and false positives associated with the presence of these analytes in blanks. Absolute method recoveries of the IDSs provide sample-specific performance information and guide data reporting. Careful selection of labeled compounds for use as IDSs is important because both inexact IDS-analyte matches and deuterium label loss affect an IDS’s ability to emulate analyte performance. Six IDS compounds initially tested and applied in this method exhibited deuterium loss and are not used in the final method.

Evaluation of a tunable bandpass reaction cell for an inductively coupled plasma mass spectrometer for the determination of chromium and vanadium in serum and urine

NASA Astrophysics Data System (ADS)

Nixon, David E.; Neubauer, Kenneth R.; Eckdahl, Steven J.; Butz, John A.; Burritt, Mary F.

2002-05-01

A Dynamic Reaction Cell™ inductively coupled argon plasma mass spectrometer (DRC-ICP-MS) was evaluated for the determination of chromium and vanadium in serum and urine. Reaction cell conditions were evaluated for the elimination of ArC + and ClOH + interferences on chromium at mass 52 and OCl + on vanadium at mass 51. A diluent containing only 1% nitric acid and internal standards (Y and Ga) was used to prepare serum and urine for analysis. Instrument response calibration was achieved by using aqueous acidic standards spiked into pooled sera or urine matrices. The slopes of the calibration curves prepared in urine and serum matrices were nearly identical. On average, chromium detection limits are 2.5 times lower using the DRC than Zeeman graphite furnace atomic absorption spectrometry (ZGFAAS). Vanadium detection limits are approximately 50 times lower. Average detection limits achieved with DRC-ICP-MS are 0.075 μg Cr/l and 0.028 μg V/l. Average results for the analysis of National Institute of Standards and Technology Standard Reference Material (NIST SRM) 1598 Bovine Serum (attained over 22 days) are: 0.14 μg Cr/l and 0.068 μg V/l. The reference concentrations for vanadium and chromium in NIST SRM 1598 are (0.06) μg V/l and 0.14±0.08 μg Cr/l, respectively. Results for chromium and vanadium determinations on ICP-MS survey samples from the Toxocologie du Quebec are equivalent to those reported by high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) for the same survey samples.

Model fit evaluation in multilevel structural equation models

PubMed Central

Ryu, Ehri

2014-01-01

Assessing goodness of model fit is one of the key questions in structural equation modeling (SEM). Goodness of fit is the extent to which the hypothesized model reproduces the multivariate structure underlying the set of variables. During the earlier development of multilevel structural equation models, the “standard” approach was to evaluate the goodness of fit for the entire model across all levels simultaneously. The model fit statistics produced by the standard approach have a potential problem in detecting lack of fit in the higher-level model for which the effective sample size is much smaller. Also when the standard approach results in poor model fit, it is not clear at which level the model does not fit well. This article reviews two alternative approaches that have been proposed to overcome the limitations of the standard approach. One is a two-step procedure which first produces estimates of saturated covariance matrices at each level and then performs single-level analysis at each level with the estimated covariance matrices as input (Yuan and Bentler, 2007). The other level-specific approach utilizes partially saturated models to obtain test statistics and fit indices for each level separately (Ryu and West, 2009). Simulation studies (e.g., Yuan and Bentler, 2007; Ryu and West, 2009) have consistently shown that both alternative approaches performed well in detecting lack of fit at any level, whereas the standard approach failed to detect lack of fit at the higher level. It is recommended that the alternative approaches are used to assess the model fit in multilevel structural equation model. Advantages and disadvantages of the two alternative approaches are discussed. The alternative approaches are demonstrated in an empirical example. PMID:24550882

[PAH Cations as Viable Carriers of DIBs

NASA Technical Reports Server (NTRS)

Snow, Ted

1998-01-01

This report is intended to fill in the blanks in NASA's file system for our lab astro study of molecular ions of astrophysical interest. In order to give NASA what it needs for its files, I attach below the text of the section from our recent proposal to continue this work, in which we describe progress to date, including a large number of publications. Our initial studies were focused on PAH cations, which appear to be viable candidates as the carriers of the DIBs, an idea that has been supported by laboratory spectroscopy of PAH cations in inert matrices. Beginning with the simplest aromatic (benzene; C6H6) and moving progressively to larger species (naphthalene, C10OH8; pyrene, C16H10; and most recently chrysene, C18H12), we have been able to derive rate coefficients for reactions with neutral spices that are abundant in the diffuse interstellar medium.

Part 1--unravelling primary health care conceptual predicaments through the lenses of complexity and political economy: a position paper for progressive transformation.

PubMed

Félix-Bortolotti, Margot

2009-10-01

To disentangle the concepts of primary health care and primary care as well as their conceptual and empirical ramifications for progressive transformation. over 400 international and interdisciplinary abstracts and papers with 96 annotated bibliography abstracts of literature across multiple dimensions relating to the knowledge base around mechanisms in PHC development were reviewed. The text is confronted with the reality, as it exists in the field and makes the case for complexity perspectives to assess this phenomenon in its context. PHC complexity is an important analytical tool to interrogate the ways in which this phenomenon is socially constructed as well as in the matrices in which it is embedded. It is also a potent analytical tool to assist in the deconstruction of prevalent linear thinking built around PHC as a whole.

A Brief Historical Introduction to Matrices and Their Applications

ERIC Educational Resources Information Center

Debnath, L.

2014-01-01

This paper deals with the ancient origin of matrices, and the system of linear equations. Included are algebraic properties of matrices, determinants, linear transformations, and Cramer's Rule for solving the system of algebraic equations. Special attention is given to some special matrices, including matrices in graph theory and electrical…

JTEC panel report on advanced composites in Japan

NASA Technical Reports Server (NTRS)

Diefendorf, R. J.; Grisaffe, S. J.; Hillig, W. B.; Perepezko, J. H.; Pipes, R. B.; Sheehan, J. E.

1991-01-01

The JTEC Panel on Advanced Composites visited Japan and surveyed the status and future directions of Japanese high performance ceramic and carbon fibers and their composites in metal, intermetallic, ceramic and carbon matrices. The panel's interests included not only what composite systems were chosen, but also how these systems were developed. A strong carbon and fiber industry makes Japan the leader in carbon fiber technology. Japan has initiated an oxidation resistant carbon/carbon composite program. The goals for this program are ambitious, and it is just starting, but its progress should be closely monitored in the United States.

Nanocomposites Derived from Polymers and Inorganic Nanoparticles

PubMed Central

Jeon, In-Yup; Baek, Jong-Beom

2010-01-01

Polymers are considered to be good hosting matrices for composite materials because they can easily be tailored to yield a variety of bulk physical properties. Moreover, organic polymers generally have long-term stability and good processability. Inorganic nanoparticles possess outstanding optical, catalytic, electronic and magnetic properties, which are significantly different their bulk states. By combining the attractive functionalities of both components, nanocomposites derived from organic polymers and inorganic nanoparticles are expected to display synergistically improved properties. The potential applications of the resultant nanocomposites are various, e.g. automotive, aerospace, opto-electronics, etc. Here, we review recent progress in polymer-based inorganic nanoparticle composites.

Fundamentals and advances in magnetic hyperthermia

NASA Astrophysics Data System (ADS)

Périgo, E. A.; Hemery, G.; Sandre, O.; Ortega, D.; Garaio, E.; Plazaola, F.; Teran, F. J.

2015-12-01

Nowadays, magnetic hyperthermia constitutes a complementary approach to cancer treatment. The use of magnetic particles as heating mediators, proposed in the 1950s, provides a novel strategy for improving tumor treatment and, consequently, patient's quality of life. This review reports a broad overview about several aspects of magnetic hyperthermia addressing new perspectives and the progress on relevant features such as the ad hoc preparation of magnetic nanoparticles, physical modeling of magnetic heating, methods to determine the heat dissipation power of magnetic colloids including the development of experimental apparatus and the influence of biological matrices on the heating efficiency.

Laminin active peptide/agarose matrices as multifunctional biomaterials for tissue engineering.

PubMed

Yamada, Yuji; Hozumi, Kentaro; Aso, Akihiro; Hotta, Atsushi; Toma, Kazunori; Katagiri, Fumihiko; Kikkawa, Yamato; Nomizu, Motoyoshi

2012-06-01

Cell adhesive peptides derived from extracellular matrix components are potential candidates to afford bio-adhesiveness to cell culture scaffolds for tissue engineering. Previously, we covalently conjugated bioactive laminin peptides to polysaccharides, such as chitosan and alginate, and demonstrated their advantages as biomaterials. Here, we prepared functional polysaccharide matrices by mixing laminin active peptides and agarose gel. Several laminin peptide/agarose matrices showed cell attachment activity. In particular, peptide AG73 (RKRLQVQLSIRT)/agarose matrices promoted strong cell attachment and the cell behavior depended on the stiffness of agarose matrices. Fibroblasts formed spheroid structures on the soft AG73/agarose matrices while the cells formed a monolayer with elongated morphologies on the stiff matrices. On the stiff AG73/agarose matrices, neuronal cells extended neuritic processes and endothelial cells formed capillary-like networks. In addition, salivary gland cells formed acini-like structures on the soft matrices. These results suggest that the peptide/agarose matrices are useful for both two- and three-dimensional cell culture systems as a multifunctional biomaterial for tissue engineering. Copyright © 2012 Elsevier Ltd. All rights reserved.

A Comparison of Pseudo-Maximum Likelihood and Asymptotically Distribution-Free Dynamic Factor Analysis Parameter Estimation in Fitting Covariance Structure Models to Block-Toeplitz Matrices Representing Single-Subject Multivariate Time-Series.

ERIC Educational Resources Information Center

Molenaar, Peter C. M.; Nesselroade, John R.

1998-01-01

Pseudo-Maximum Likelihood (p-ML) and Asymptotically Distribution Free (ADF) estimation methods for estimating dynamic factor model parameters within a covariance structure framework were compared through a Monte Carlo simulation. Both methods appear to give consistent model parameter estimates, but only ADF gives standard errors and chi-square…

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the direct detection of 2-monochloropropanediol (2-MCPD) esters in edible oils.

PubMed

MacMahon, Shaun; Ridge, Clark D; Begley, Timothy H

2014-12-03

A new analytical method has been developed and validated for the detection and quantification of 2-monochloropropanediol (2-MCPD) esters in edible oils. The target compounds are potentially carcinogenic contaminants formed during the processing of edible oils. As the 2-MCPD esters that occur most frequently in refined edible oils were not commercially available, standards were synthesized with identity and purity (95+%) confirmed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and (1)H NMR. Target analytes are separated from edible oil matrices using a two-step solid-phase extraction (SPE) procedure. The extracts are then analyzed using LC-MS/MS with electrospray ionization (ESI). The method has been validated for 11 2-MCPD diesters and 3 2-MCPD monoesters in soybean oil, olive oil, and palm oil using an external calibration curve. The ranges of average recoveries and relative standard deviations (RSD) across the three oil matrices at three spiking concentrations are 79-106% (3-13% RSD) for the 2-MCPD diesters and 72-108% (4-17% RSD) for the 2-MCPD monoesters, with limits of quantitation at or below 30 ng/g for the diesters and 90 ng/g for the monoesters.

Stability of steviol glycosides in several food matrices.

PubMed

Jooken, Etienne; Amery, Ruis; Struyf, Tom; Duquenne, Barbara; Geuns, Jan; Meesschaert, Boudewijn

2012-10-24

As steviol glycosides are now allowed as a food additive in the European market, it is important to assess the stability of these steviol glycosides after they have been added to different food matrices. We analyzed and tested the stability of steviol glycosides in semiskimmed milk, soy drink, fermented milk drink, ice cream, full-fat and skimmed set yogurt, dry biscuits, and jam. The fat was removed by centrifugation from the dairy and soy drink samples. Proteins were precipitated by the addition of acetonitrile and also removed by centrifugation. Samples of jam were extracted with water. Dry biscuits were extracted with ethanol. The resulting samples were concentrated with solid-phase extraction and analyzed by high-performance liquid chromatography on a C18 stationary phase and a gradient of acetonitrile/aqueous 25 mM phosphoric acid. The accuracy was checked using a standard addition on some samples. For assessing the stability of the steviol glycosides, samples were stored in conditions relevant to each food matrix and analyzed periodically. The results indicate that steviol glycosides can be analyzed with good precision and accuracy in these food categories. The recovery was between 96 and 103%. The method was also validated by standard addition, which showed excellent agreement with the external calibration curve. No sign of decomposition of steviol glycosides was found in any of the samples.

FISHing for bacteria in food--a promising tool for the reliable detection of pathogenic bacteria?

PubMed

Rohde, Alexander; Hammerl, Jens Andre; Appel, Bernd; Dieckmann, Ralf; Al Dahouk, Sascha

2015-04-01

Foodborne pathogens cause millions of infections every year and are responsible for considerable economic losses worldwide. The current gold standard for the detection of bacterial pathogens in food is still the conventional cultivation following standardized and generally accepted protocols. However, these methods are time-consuming and do not provide fast information about food contaminations and thus are limited in their ability to protect consumers in time from potential microbial hazards. Fluorescence in situ hybridization (FISH) represents a rapid and highly specific technique for whole-cell detection. This review aims to summarize the current data on FISH-testing for the detection of pathogenic bacteria in different food matrices and to evaluate its suitability for the implementation in routine testing. In this context, the use of FISH in different matrices and their pretreatment will be presented, the sensitivity and specificity of FISH tests will be considered and the need for automation shall be discussed as well as the use of technological improvements to overcome current hurdles for a broad application in monitoring food safety. In addition, the overall economical feasibility will be assessed in a rough calculation of costs, and strengths and weaknesses of FISH are considered in comparison with traditional and well-established detection methods. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

Division of methods for counting helminths' eggs and the problem of efficiency of these methods.

PubMed

Jaromin-Gleń, Katarzyna; Kłapeć, Teresa; Łagód, Grzegorz; Karamon, Jacek; Malicki, Jacek; Skowrońska, Agata; Bieganowski, Andrzej

2017-03-21

From the sanitary and epidemiological aspects, information concerning the developmental forms of intestinal parasites, especially the eggs of helminths present in our environment in: water, soil, sandpits, sewage sludge, crops watered with wastewater are very important. The methods described in the relevant literature may be classified in various ways, primarily according to the methodology of the preparation of samples from environmental matrices prepared for analysis, and the sole methods of counting and chambers/instruments used for this purpose. In addition, there is a possibility to perform the classification of the research methods analyzed from the aspect of the method and time of identification of the individuals counted, or the necessity for staining them. Standard methods for identification of helminths' eggs from environmental matrices are usually characterized by low efficiency, i.e. from 30% to approximately 80%. The efficiency of the method applied may be measured in a dual way, either by using the method of internal standard or the 'Split/Spike' method. While measuring simultaneously in an examined object the efficiency of the method and the number of eggs, the 'actual' number of eggs may be calculated by multiplying the obtained value of the discovered eggs of helminths by inverse efficiency.

Genetic code, hamming distance and stochastic matrices.

PubMed

He, Matthew X; Petoukhov, Sergei V; Ricci, Paolo E

2004-09-01

In this paper we use the Gray code representation of the genetic code C=00, U=10, G=11 and A=01 (C pairs with G, A pairs with U) to generate a sequence of genetic code-based matrices. In connection with these code-based matrices, we use the Hamming distance to generate a sequence of numerical matrices. We then further investigate the properties of the numerical matrices and show that they are doubly stochastic and symmetric. We determine the frequency distributions of the Hamming distances, building blocks of the matrices, decomposition and iterations of matrices. We present an explicit decomposition formula for the genetic code-based matrix in terms of permutation matrices, which provides a hypercube representation of the genetic code. It is also observed that there is a Hamiltonian cycle in a genetic code-based hypercube.

General squark flavour mixing: constraints, phenomenology and benchmarks

DOE PAGES

De Causmaecker, Karen; Fuks, Benjamin; Herrmann, Bjorn; ...

2015-11-19

Here, we present an extensive study of non-minimal flavour violation in the squark sector in the framework of the Minimal Supersymmetric Standard Model. We investigate the effects of multiple non-vanishing flavour-violating elements in the squark mass matrices by means of a Markov Chain Monte Carlo scanning technique and identify parameter combinations that are favoured by both current data and theoretical constraints. We then detail the resulting distributions of the flavour-conserving and flavour-violating model parameters. Based on this analysis, we propose a set of benchmark scenarios relevant for future studies of non-minimal flavour violation in the Minimal Supersymmetric Standard Model.

Physical and perceptual estimation of differences between loudspeakers

NASA Astrophysics Data System (ADS)

Lavandier, Mathieu; Herzog, Philippe; Meunier, Sabine

2006-12-01

Differentiating the restitution of timbre by several loudspeakers may result from standard measurements, or from listening tests. This work proposes a protocol keeping a close relationship between the objective and perceptual evaluations: the stimuli are musical excerpts, and the measuring environment is a standard listening room. The protocol involves recordings made at a listener position, and objective dissimilarities are computed using an auditory model simulating masking effects. The resulting data correlate very well with listening tests using the same recordings, and show similar dependencies on the major parameters identified from the dissimilarity matrices. To cite this article: M. Lavandier et al., C. R. Mecanique 334 (2006).

Cell-adhesive RGD peptide-displaying M13 bacteriophage/PLGA nanofiber matrices for growth of fibroblasts.

PubMed

Shin, Yong Cheol; Lee, Jong Ho; Jin, Linhua; Kim, Min Jeong; Oh, Jin-Woo; Kim, Tai Wan; Han, Dong-Wook

2014-01-01

M13 bacteriophages can be readily fabricated as nanofibers due to non-toxic bacterial virus with a nanofiber-like shape. In the present study, we prepared hybrid nanofiber matrices composed of poly(lactic-co-glycolic acid, PLGA) and M13 bacteriophages which were genetically modified to display the RGD peptide on their surface (RGD-M13 phage). The surface morphology and chemical composition of hybrid nanofiber matrices were characterized by scanning electron microscopy (SEM) and Raman spectroscopy, respectively. Immunofluorescence staining was conducted to investigate the existence of M13 bacteriophages in RGD-M13 phage/PLGA hybrid nanofibers. In addition, the attachment and proliferation of three different types of fibroblasts on RGD-M13 phage/PLGA nanofiber matrices were evaluated to explore how fibroblasts interact with these matrices. SEM images showed that RGD-M13 phage/PLGA hybrid matrices had the non-woven porous structure, quite similar to that of natural extracellular matrices, having an average fiber diameter of about 190 nm. Immunofluorescence images and Raman spectra revealed that RGD-M13 phages were homogeneously distributed in entire matrices. Moreover, the attachment and proliferation of fibroblasts cultured on RGD-M13 phage/PLGA matrices were significantly enhanced due to enriched RGD moieties on hybrid matrices. These results suggest that RGD-M13 phage/PLGA matrices can be efficiently used as biomimetic scaffolds for tissue engineering applications.

Bayes linear covariance matrix adjustment

NASA Astrophysics Data System (ADS)

Wilkinson, Darren J.

1995-12-01

In this thesis, a Bayes linear methodology for the adjustment of covariance matrices is presented and discussed. A geometric framework for quantifying uncertainties about covariance matrices is set up, and an inner-product for spaces of random matrices is motivated and constructed. The inner-product on this space captures aspects of our beliefs about the relationship between covariance matrices of interest to us, providing a structure rich enough for us to adjust beliefs about unknown matrices in the light of data such as sample covariance matrices, exploiting second-order exchangeability and related specifications to obtain representations allowing analysis. Adjustment is associated with orthogonal projection, and illustrated with examples of adjustments for some common problems. The problem of adjusting the covariance matrices underlying exchangeable random vectors is tackled and discussed. Learning about the covariance matrices associated with multivariate time series dynamic linear models is shown to be amenable to a similar approach. Diagnostics for matrix adjustments are also discussed.

Pupil Diameter Tracks the Exploration-Exploitation Trade-off during Analogical Reasoning and Explains Individual Differences in Fluid Intelligence.

PubMed

Hayes, Taylor R; Petrov, Alexander A

2016-02-01

The ability to adaptively shift between exploration and exploitation control states is critical for optimizing behavioral performance. Converging evidence from primate electrophysiology and computational neural modeling has suggested that this ability may be mediated by the broad norepinephrine projections emanating from the locus coeruleus (LC) [Aston-Jones, G., & Cohen, J. D. An integrative theory of locus coeruleus-norepinephrine function: Adaptive gain and optimal performance. Annual Review of Neuroscience, 28, 403-450, 2005]. There is also evidence that pupil diameter covaries systematically with LC activity. Although imperfect and indirect, this link makes pupillometry a useful tool for studying the locus coeruleus norepinephrine system in humans and in high-level tasks. Here, we present a novel paradigm that examines how the pupillary response during exploration and exploitation covaries with individual differences in fluid intelligence during analogical reasoning on Raven's Advanced Progressive Matrices. Pupillometry was used as a noninvasive proxy for LC activity, and concurrent think-aloud verbal protocols were used to identify exploratory and exploitative solution periods. This novel combination of pupillometry and verbal protocols from 40 participants revealed a decrease in pupil diameter during exploitation and an increase during exploration. The temporal dynamics of the pupillary response was characterized by a steep increase during the transition to exploratory periods, sustained dilation for many seconds afterward, and followed by gradual return to baseline. Moreover, the individual differences in the relative magnitude of pupillary dilation accounted for 16% of the variance in Advanced Progressive Matrices scores. Assuming that pupil diameter is a valid index of LC activity, these results establish promising preliminary connections between the literature on locus coeruleus norepinephrine-mediated cognitive control and the literature on analogical reasoning and fluid intelligence.

Individual differences in fluid intelligence predicts inattentional blindness in a sample of older adults: a preliminary study.

PubMed

O'Shea, Deirdre M; Fieo, Robert A

2015-07-01

Previous research has shown that aging increases susceptibility to inattentional blindness (Graham and Burke, Psychol Aging 26:162, 2011) as well as individual differences in cognitive ability related to working memory and executive functions in separate studies. Therefore, the present study was conducted in an attempt to bridge a gap that involved investigating 'age-sensitive' cognitive abilities that may predict inattentional blindness in a sample of older adults. We investigated whether individual differences in general fluid intelligence and speed of processing would predict inattentional blindness in our sample of older adults. Thirty-six healthy older adults took part in the study. Using the inattentional blindness paradigm developed by Most et al. (Psychol Rev 112:217, 2005), we investigated whether rates of inattentional blindness could be predicted by participant's performance on the Raven's Advanced Progressive Matrices and a choice-reaction time task. A Mann-Whitney U test revealed that a higher score on the Raven's Advanced Progressive Matrices was significantly associated with lower incidences of inattentional blindness. However, a t test revealed that choice-reaction times were not significantly associated with inattentional blindness. Preliminary results from the present study suggest that individual differences in general fluid intelligence are predictive of inattentional blindness in older adults but not speed of processing. Moreover, our findings are consistent with previous studies that have suggested executive attention control may be the source of these individual differences. These findings also highlight the association between attention and general fluid intelligence and how it may impact environmental awareness. Future research would benefit from repeating these analyses in a larger sample and also including a younger comparison group.

Matrix Stiffness Corresponding to Strictured Bowel Induces a Fibrogenic Response in Human Colonic Fibroblasts

PubMed Central

Johnson, Laura A.; Rodansky, Eva S.; Sauder, Kay L.; Horowitz, Jeffrey C.; Mih, Justin D.; Tschumperlin, Daniel J.; Higgins, Peter D.

2013-01-01

Background Crohn’s disease is characterized by repeated cycles of inflammation and mucosal healing which ultimately progress to intestinal fibrosis. This inexorable progression towards fibrosis suggests that fibrosis becomes inflammation-independent and auto-propagative. We hypothesized that matrix stiffness regulates this auto-propagation of intestinal fibrosis. Methods The stiffness of fresh ex vivo samples from normal human small intestine, Crohn’s disease strictures, and the unaffected margin were measured with a microelastometer. Normal human colonic fibroblasts were cultured on physiologically normal or pathologically stiff matrices corresponding to the physiological stiffness of normal or fibrotic bowel. Cellular response was assayed for changes in cell morphology, α-smooth muscle actin (αSMA) staining, and gene expression. Results Microelastometer measurements revealed a significant increase in colonic tissue stiffness between normal human colon and Crohn’s strictures as well as between the stricture and adjacent tissue margin. In Ccd-18co cells grown on stiff matrices corresponding to Crohn’s strictures, cellular proliferation increased. Pathologic stiffness induced a marked change in cell morphology and increased αSMA protein expression. Growth on a stiff matrix induced fibrogenic gene expression, decreased matrix metalloproteinase and pro-inflammatory gene expression, and was associated with nuclear localization of the transcriptional cofactor MRTF-A. Conclusions Matrix stiffness, representative of the pathological stiffness of Crohn’s strictures, activates human colonic fibroblasts to a fibrogenic phenotype. Matrix stiffness affects multiple pathways suggesting the mechanical properties of the cellular environment are critical to fibroblast function and may contribute to autopropagation of intestinal fibrosis in the absence of inflammation, thereby contributing to the intractable intestinal fibrosis characteristic of Crohn’s disease. PMID:23502354

Predicting neo-adjuvant chemotherapy response and progression-free survival of locally advanced breast cancer using textural features of intratumoral heterogeneity on F-18 FDG PET/CT and diffusion-weighted MR imaging.

PubMed

Yoon, Hai-Jeon; Kim, Yemi; Chung, Jin; Kim, Bom Sahn

2018-03-30

Predicting response to neo-adjuvant chemotherapy (NAC) and survival in locally advanced breast cancer (LABC) is important. This study investigated the prognostic value of tumor heterogeneity evaluated with textural analysis through F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) and diffusion-weighted imaging (DWI). We enrolled 83 patients with LABC who had completed NAC and curative surgery. Tumor texture indices from pretreatment FDG PET and DWI were extracted from histogram analysis and 7 different parent matrices: co-occurrence matrix, the voxel-alignment matrix, neighborhood intensity difference matrix, intensity size-zone matrix (ISZM), normalized gray-level co-occurrence matrix (NGLCM), neighboring gray-level dependence matrix (NGLDM), and texture spectrum matrix. The predictive values of textural features were tested regarding both pathologic NAC response and progression-free survival. Among 83 patients, 46 were pathologic responders, while 37 were nonresponders. The PET texture indices from 7 parent matrices, DWI texture indices from histogram, and 1 parent matrix (NGLCM) showed significant differences according to NAC response. On multivariable analysis, number nonuniformity of PET extracted from the NGLDM was an independent predictor of pathologic response (P = .009). During a median follow-up period of 17.3 months, 14 patients experienced recurrence. High-intensity zone emphasis (HIZE) and high-intensity short-zone emphasis (HISZE) from PET extracted from ISZM were significant textural predictors (P = .011 and P = .033). On Cox regression analysis, only HIZE was a significant predictor of recurrence (P = .027), while HISZE showed borderline significance (P = .107). Tumor texture indices are useful for NAC response prediction in LABC. Moreover, PET texture indices can help to predict disease recurrence. © 2018 Wiley Periodicals, Inc.

Design of a One-Dimensional Sextupole Using Semi-Analytic Methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gupta, L.; Nagaitsev, S.; Baturin, S. S.

Sextupole magnets provide position-dependent momentum kicks and are tuned to provide the correct kicks to parti- cles within a small acceptance region in phase space. Sextupoles are useful and even necessary in circular accelerators for chromaticity corrections. They are routinely used in most rings, i.e. CESR. Although sextupole magnets are necessary for particle energy corrections, they also have undesirable effects on dynamic aperture, especially because of their non- linear coupling term in the momentum kick. Studies of integrable systems suggest that there is an analytic way to create transport lattices with specific transfer matrices that limit the momentum kick tomore » one dimension. A one-dimension sex- tupole is needed for chromaticity corrections: a horizontal sextupole for horizontal bending magnets. We know how to make a “composite” horizontal sextupole using regular 2D sextupoles and linear transfer matrices in an ideal thin-lens approximation. Thus, one could create an accelerator lattice using linear elements, in series with sextupole magnets to create a “1D sextupole”. This paper describes progress to- wards realizing a realistic focusing lattice resulting in a 1D sextupole.« less

Substituted amylose matrices for oral drug delivery

NASA Astrophysics Data System (ADS)

Moghadam, S. H.; Wang, H. W.; Saddar El-Leithy, E.; Chebli, C.; Cartilier, L.

2007-03-01

High amylose corn starch was used to obtain substituted amylose (SA) polymers by chemically modifying hydroxyl groups by an etherification process using 1,2-epoxypropanol. Tablets for drug-controlled release were prepared by direct compression and their release properties assessed by an in vitro dissolution test (USP XXIII no 2). The polymer swelling was characterized by measuring gravimetrically the water uptake ability of polymer tablets. SA hydrophilic matrix tablets present sequentially a burst effect, typical of hydrophilic matrices, and a near constant release, typical of reservoir systems. After the burst effect, surface pores disappear progressively by molecular association of amylose chains; this allows the creation of a polymer layer acting as a diffusion barrier and explains the peculiar behaviour of SA polymers. Several formulation parameters such as compression force, drug loading, tablet weight and insoluble diluent concentration were investigated. On the other hand, tablet thickness, scanning electron microscope analysis and mercury intrusion porosimetry showed that the high crushing strength values observed for SA tablets were due to an unusual melting process occurring during tabletting although the tablet external layer went only through densification, deformation and partial melting. In contrast, HPMC tablets did not show any traces of a melting process.

Tissue engineering in urothelium regeneration.

PubMed

Vaegler, Martin; Maurer, Sabine; Toomey, Patricia; Amend, Bastian; Sievert, Karl-Dietrich

2015-03-01

The development of therapeutic treatments to regenerate urothelium, manufacture tissue equivalents or neourethras for in-vivo application is a significant challenge in the field of tissue engineering. Many studies have focused on urethral defects that, in most cases, inadequately address current therapies. This article reviews the primary tissue engineering strategies aimed at the clinical requirements for urothelium regeneration while concentrating on promising investigations in the use of grafts, cellular preparations, as well as seeded or unseeded natural and synthetic materials. Despite significant progress being made in the development of scaffolds and matrices, buccal mucosa transplants have not been replaced. Recently, graft tissues appear to have an advantage over the use of matrices. These therapies depend on cell isolation and propagation in vitro that require, not only substantial laboratory resources, but also subsequent surgical implant procedures. The choice of the correct cell source is crucial when determining an in-vivo application because of the risks of tissue changes and abnormalities that may result in donor site morbidity. Addressing an appropriately-designed animal model and relevant regulatory issues is of fundamental importance for the principal investigators when a therapy using cellular components has been developed for clinical use. Copyright © 2014 Elsevier B.V. All rights reserved.

Damage location and quantification of a pretensioned concrete beam using stochastic subspace identification

NASA Astrophysics Data System (ADS)

Cancelli, Alessandro; Micheli, Laura; Laflamme, Simon; Alipour, Alice; Sritharan, Sri; Ubertini, Filippo

2017-04-01

Stochastic subspace identification (SSID) is a first-order linear system identification technique enabling modal analysis through the time domain. Research in the field of structural health monitoring has demonstrated that SSID can be used to successfully retrieve modal properties, including modal damping ratios, using output-only measurements. In this paper, the utilization of SSID for indirectly retrieving structures' stiffness matrix was investigated, through the study of a simply supported reinforced concrete beam subjected to dynamic loads. Hence, by introducing a physical model of the structure, a second-order identification method is achieved. The reconstruction is based on system condensation methods, which enables calculation of reduced order stiffness, damping, and mass matrices for the structural system. The methods compute the reduced order matrices directly from the modal properties, obtained through the use of SSID. Lastly, the reduced properties of the system are used to reconstruct the stiffness matrix of the beam. The proposed approach is first verified through numerical simulations and then validated using experimental data obtained from a full-scale reinforced concrete beam that experienced progressive damage. Results show that the SSID technique can be used to diagnose, locate, and quantify damage through the reconstruction of the stiffness matrix.

On the behavior of the leading eigenvalue of Eigen's evolutionary matrices.

PubMed

Semenov, Yuri S; Bratus, Alexander S; Novozhilov, Artem S

2014-12-01

We study general properties of the leading eigenvalue w¯(q) of Eigen's evolutionary matrices depending on the replication fidelity q. This is a linear algebra problem that has various applications in theoretical biology, including such diverse fields as the origin of life, evolution of cancer progression, and virus evolution. We present the exact expressions for w¯(q),w¯(')(q),w¯('')(q) for q = 0, 0.5, 1 and prove that the absolute minimum of w¯(q), which always exists, belongs to the interval (0, 0.5]. For the specific case of a single peaked landscape we also find lower and upper bounds on w¯(q), which are used to estimate the critical mutation rate, after which the distribution of the types of individuals in the population becomes almost uniform. This estimate is used as a starting point to conjecture another estimate, valid for any fitness landscape, and which is checked by numerical calculations. The last estimate stresses the fact that the inverse dependence of the critical mutation rate on the sequence length is not a generally valid fact. Copyright © 2014 Elsevier Inc. All rights reserved.

Good cognitive performances in a child with Prader-Willi syndrome.

PubMed

Nugnes, Rosa; Zito, Eugenio; Mozzillo, Enza; Camarca, Maria Erminia; Riccio, Maria Pia; Terrone, Gaetano; Melis, Daniela; Bravaccio, Carmela; Franzese, Adriana

2013-11-15

We report the case of a child affected by Prader-Willi syndrome (PWS) with good cognitive performances and without relevant behavioral abnormalities.The diagnosis of PWS, suspected on the basis of clinical features and past history, was confirmed by DNA methylation analysis. Additional genetic testing revealed a maternal uniparental disomy. Intellectual profile was analyzed by WISC-III and Raven's Progressive Matrices CPM, while the behavior was evaluated by K-SADS-PL and Child Behavior Checklist/4-18 to the parents.WISC-III test showed a Total Intelligence Quotient (T-IQ = 79) at the border level for age. The Verbal Intelligence Quotient (V-IQ) showed a lower score than the Performance Intelligence Quotient (P-IQ) (78 and 85, respectively). Raven's Matrices CPM showed an intelligence level at 75-90° percentile for age. Concerning behavioral evaluation, a difficulty in impulse control was observed, with persistent but controllable search for food, without a clear psychopathological meaning. Also according to K-SADS-PL no areas of psychopathological dimensions were detected. In conclusion, in presence of consisting clinical features of PWS and high diagnostic suspicion, the diagnosis of PWS should be considered even in presence of a borderline IQ and in absence of psychopathological abnormalities.

Introducing Explorer of Taxon Concepts with a case study on spider measurement matrix building.

PubMed

Cui, Hong; Xu, Dongfang; Chong, Steven S; Ramirez, Martin; Rodenhausen, Thomas; Macklin, James A; Ludäscher, Bertram; Morris, Robert A; Soto, Eduardo M; Koch, Nicolás Mongiardino

2016-11-17

Taxonomic descriptions are traditionally composed in natural language and published in a format that cannot be directly used by computers. The Exploring Taxon Concepts (ETC) project has been developing a set of web-based software tools that convert morphological descriptions published in telegraphic style to character data that can be reused and repurposed. This paper introduces the first semi-automated pipeline, to our knowledge, that converts morphological descriptions into taxon-character matrices to support systematics and evolutionary biology research. We then demonstrate and evaluate the use of the ETC Input Creation - Text Capture - Matrix Generation pipeline to generate body part measurement matrices from a set of 188 spider morphological descriptions and report the findings. From the given set of spider taxonomic publications, two versions of input (original and normalized) were generated and used by the ETC Text Capture and ETC Matrix Generation tools. The tools produced two corresponding spider body part measurement matrices, and the matrix from the normalized input was found to be much more similar to a gold standard matrix hand-curated by the scientist co-authors. Special conventions utilized in the original descriptions (e.g., the omission of measurement units) were attributed to the lower performance of using the original input. The results show that simple normalization of the description text greatly increased the quality of the machine-generated matrix and reduced edit effort. The machine-generated matrix also helped identify issues in the gold standard matrix. ETC Text Capture and ETC Matrix Generation are low-barrier and effective tools for extracting measurement values from spider taxonomic descriptions and are more effective when the descriptions are self-contained. Special conventions that make the description text less self-contained challenge automated extraction of data from biodiversity descriptions and hinder the automated reuse of the published knowledge. The tools will be updated to support new requirements revealed in this case study.

Numerical calculation of thermo-mechanical problems at large strains based on complex step derivative approximation of tangent stiffness matrices

NASA Astrophysics Data System (ADS)

Balzani, Daniel; Gandhi, Ashutosh; Tanaka, Masato; Schröder, Jörg

2015-05-01

In this paper a robust approximation scheme for the numerical calculation of tangent stiffness matrices is presented in the context of nonlinear thermo-mechanical finite element problems and its performance is analyzed. The scheme extends the approach proposed in Kim et al. (Comput Methods Appl Mech Eng 200:403-413, 2011) and Tanaka et al. (Comput Methods Appl Mech Eng 269:454-470, 2014 and bases on applying the complex-step-derivative approximation to the linearizations of the weak forms of the balance of linear momentum and the balance of energy. By incorporating consistent perturbations along the imaginary axis to the displacement as well as thermal degrees of freedom, we demonstrate that numerical tangent stiffness matrices can be obtained with accuracy up to computer precision leading to quadratically converging schemes. The main advantage of this approach is that contrary to the classical forward difference scheme no round-off errors due to floating-point arithmetics exist within the calculation of the tangent stiffness. This enables arbitrarily small perturbation values and therefore leads to robust schemes even when choosing small values. An efficient algorithmic treatment is presented which enables a straightforward implementation of the method in any standard finite-element program. By means of thermo-elastic and thermo-elastoplastic boundary value problems at finite strains the performance of the proposed approach is analyzed.

Development and Validation of an Inductively Coupled Plasma Mass Spectrometry (ICP-MS) Method for Quantitative Analysis of Platinum in Plasma, Urine, and Tissues.

PubMed

Zhang, Ti; Cai, Shuang; Forrest, Wai Chee; Mohr, Eva; Yang, Qiuhong; Forrest, M Laird

2016-09-01

Cisplatin, a platinum chemotherapeutic, is one of the most commonly used chemotherapeutic agents for many solid tumors. In this work, we developed and validated an inductively coupled plasma mass spectrometry (ICP-MS) method for quantitative determination of platinum levels in rat urine, plasma, and tissue matrices including liver, brain, lungs, kidney, muscle, heart, spleen, bladder, and lymph nodes. The tissues were processed using a microwave accelerated reaction system (MARS) system prior to analysis on an Agilent 7500 ICP-MS. According to the Food and Drug Administration guidance for industry, bioanalytical validation parameters of the method, such as selectivity, accuracy, precision, recovery, and stability were evaluated in rat biological samples. Our data suggested that the method was selective for platinum without interferences caused by other presenting elements, and the lower limit of quantification was 0.5 ppb. The accuracy and precision of the method were within 15% variation and the recoveries of platinum for all tissue matrices examined were determined to be 85-115% of the theoretical values. The stability of the platinum-containing solutions, including calibration standards, stock solutions, and processed samples in rat biological matrices was investigated. Results indicated that the samples were stable after three cycles of freeze-thaw and for up to three months. © The Author(s) 2016.

Development and Validation of an Inductively Coupled Plasma Mass Spectrometry (ICP-MS) Method for Quantitative Analysis of Platinum in Plasma, Urine, and Tissues

PubMed Central

Zhang, Ti; Cai, Shuang; Forrest, Wai Chee; Mohr, Eva; Yang, Qiuhong; Forrest, M. Laird

2016-01-01

Cisplatin, a platinum chemotherapeutic, is one of the most commonly used chemotherapeutic agents for many solid tumors. In this work, we developed and validated an inductively coupled plasma mass spectrometry (ICP-MS) method for quantitative determination of platinum levels in rat urine, plasma, and tissue matrices including liver, brain, lungs, kidney, muscle, heart, spleen, bladder, and lymph nodes. The tissues were processed using a microwave accelerated reaction system (MARS) system prior to analysis on an Agilent 7500 ICP-MS. According to the Food and Drug Administration guidance for industry, bioanalytical validation parameters of the method, such as selectivity, accuracy, precision, recovery, and stability were evaluated in rat biological samples. Our data suggested that the method was selective for platinum without interferences caused by other presenting elements, and the lower limit of quantification was 0.5 ppb. The accuracy and precision of the method were within 15% variation and the recoveries of platinum for all tissue matrices examined were determined to be 85–115% of the theoretical values. The stability of the platinum-containing solutions, including calibration standards, stock solutions, and processed samples in rat biological matrices was investigated. Results indicated that the samples were stable after three cycles of freeze–thaw and for up to three months. PMID:27527103

Determination of glyoxal and methylglyoxal in environmental and biological matrices by stir bar sorptive extraction with in-situ derivatization.

PubMed

Neng, N R; Cordeiro, C A A; Freire, A P; Nogueira, J M F

2007-10-26

Stir bar sorptive extraction with in-situ derivatization using 2,3-diaminonaphthalene (DAN) followed by liquid desorption and high performance liquid chromatography with diode array detection (SBSE(DAN)in-situ-LD-HPLC-DAD) was developed for the determination of glyoxal (Gly) and methylglyoxal (MGly) in environmental and biological matrices. DAN proved very good specificity as in-situ derivatising agent for Gly and MGly in aqueous media, allowing the formation of adducts with remarkable sensitivity, selectivity and the absence of photodegradation. Assays performed on spiked (1.0 microg L(-1)) water samples, under convenient experimental conditions, yielded recoveries of 96.2+/-7.9% for Gly and 96.1+/-6.4% for MGly. The analytical performance showed good accuracy, suitable precision (<12.0%), low detection limits (15 ng L(-1) for Gly and 25 ng L(-1) for MGly adducts) and excellent linear dynamic ranges (r2>0.99) from 0.1 to 120.0 microg L(-1). By using the standard addition method, the application of the present method to tap and swimming-pool water, beer, yeast cells suspension and urine samples allowed very good performance at the trace level. The proposed methodology proved to be a feasible alternative for routine quality control analysis, showing to be easy to implement, reliable, sensitive and with a low sample volume requirement to monitor Gly and MGly in environmental and biological matrices.

Simultaneous detection of the protozoan parasites Toxoplasma, Cryptosporidium and Giardia in food matrices and their persistence on basil leaves.

PubMed

Hohweyer, Jeanne; Cazeaux, Catherine; Travaillé, Emmanuelle; Languet, Emilie; Dumètre, Aurélien; Aubert, Dominique; Terryn, Christine; Dubey, Jitender P; Azas, Nadine; Houssin, Maryline; Loïc, Favennec; Villena, Isabelle; La Carbona, Stéphanie

2016-08-01

Toxoplasma gondii, Cryptosporidium spp. and Giardia intestinalis are emerging pathogen parasites in the food domain. However, without standardized methods for their detection in food matrices, parasitic foodborne outbreaks remain neglected. In this study, a new immunomagnetic separation assay (IMS Toxo) targeting the oocyst's wall of T. gondii was developed using a specific purified monoclonal antibody. Performance of this IMS Toxo coupled to microscopic and qPCR analyses was evaluated in terms of limit of detection (LOD) and recovery rate (RR) on: i) simple matrix (LOD = 5 oocysts; RR between 5 and 56%); ii) raspberries and basil (LOD = 33 oocysts/g; RR between 0.2 and 35%). Finally, to simultaneously extract the three protozoa from these food matrices, T. gondii oocysts were directly concentrated (without IMS Toxo) from the supernatant of the IMS of Cryptosporidium and Giardia (oo)cysts. This strategy associated to qPCR detection led to LOD <1 to 3 (oo)cysts/g and RR between 2 and 35%. This procedure was coupled to RT-qPCR analyses and showed that the three protozoa persisted on the leaves of basil and remained viable following storage at 4 °C for 8 days. These data strengthen the need to consider these protozoa in food safety. Copyright © 2016 Elsevier Ltd. All rights reserved.

Statistical Characterization of Altitude Matrices by Computer. Report 4. Frequency Distributions of Gradient.

DTIC Science & Technology

1977-01-01

balanced at the mean, with the central part steeper ( platykurtic : broad mode or truncated tails) -r flatter (leptokurtic: peaked mode or extended...and NUPUR, have negative kurtosis (they are platykurtic , with truncated tails and/or broad modes relative to their standard deviations) FERRO, on the...the other areas, and its gradients are platykurtic but almost unskewed. Hence the square root of sine transformation (Fig,15) and the log tangent

Direct synthesis of ESBO derivatives-¹⁸O labelled with dioxirane.

PubMed

La Tegola, Stefano; Annese, Cosimo; Suman, Michele; Tommasi, Immacolata; Fusco, Caterina; D'Accolti, Lucia

2013-01-01

This work addresses a new approach developed in our laboratory, consisting in the application of isolated dimethyldioxirane (DDO, 1a) labelled with ¹⁸O for synthesis of epoxidized glyceryl linoleate (Gly-LLL, 2). We expect that this work could contribute in improving analytical methods for the determination of epoxidized soybean oil (ESBO) in complex food matrices by adopting an ¹⁸O-labelled-epoxidized triacylglycerol as an internal standard.

The applications of a commercial gas/liquid separator coupled with an inductively coupled plasma mass spectrometer

PubMed Central

Hitchen, Peter; Hutton, Robert; Tye, Christopher

1992-01-01

A commercially available hydride generator, with a novel membrane gas-liquid separator, has been coupled to a new ICPMS instrument which itself features many unique design considerations. Little or no optimization of the mass spectrometer or ionization source was required to obtain excellent analytical data; and a variety of matrices have been analysed. The elements As and Se are usually used to demonstrate the effectiveness of a hydride generation system, and these are of particular importance, bearing in mind potential Ar molecular overlaps with isotopes of interest. The flexibility of the hydride generation ICP-MS system is highlighted, with the inclusion of analytical figures of merit for the elements Sn, Sb, Ge and Hg, as well as As and Se. Data obtained by ‘standard’ pneumatic nebulization on the ICP-MS is compared with that obtained with the hydride generator for all of the elements. Improvements of between 50 and 100 times were gained in measurements of three sigma detection limits for all elements in the determinations, including Hg. Measurements were made on several isotopes for particular elements, and the data is included for the purposes of comparison. Stabilities of between 1 and 2.5% were obtained for 0.5 ppb solutions over 10 min measurement periods, all data is presented without using an internal standard. Finally, analytical data from seawater standards, spiked with low levels of As and Se and calibrated against aqueous standards, demonstrate excellent recoveries. This is of particular interest bearing in mind the well-documented molecular interferences from high chloride matrices on As and Se analysis. PMID:18924920

Novel method for the determination of average molecular weight of natural polymers based on 2D DOSY NMR and chemometrics: Example of heparin.

PubMed

Monakhova, Yulia B; Diehl, Bernd W K; Do, Tung X; Schulze, Margit; Witzleben, Steffen

2018-02-05

Apart from the characterization of impurities, the full characterization of heparin and low molecular weight heparin (LMWH) also requires the determination of average molecular weight, which is closely related to the pharmaceutical properties of anticoagulant drugs. To determine average molecular weight of these animal-derived polymer products, partial least squares regression (PLS) was utilized for modelling of diffused-ordered spectroscopy NMR data (DOSY) of a representative set of heparin (n=32) and LMWH (n=30) samples. The same sets of samples were measured by gel permeation chromatography (GPC) to obtain reference data. The application of PLS to the data led to calibration models with root mean square error of prediction of 498Da and 179Da for heparin and LMWH, respectively. The average coefficients of variation (CVs) did not exceed 2.1% excluding sample preparation (by successive measuring one solution, n=5) and 2.5% including sample preparation (by preparing and analyzing separate samples, n=5). An advantage of the method is that the sample after standard 1D NMR characterization can be used for the molecular weight determination without further manipulation. The accuracy of multivariate models is better than the previous results for other matrices employing internal standards. Therefore, DOSY experiment is recommended to be employed for the calculation of molecular weight of heparin products as a complementary measurement to standard 1D NMR quality control. The method can be easily transferred to other matrices as well. Copyright © 2017 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eppich, Gary R.; Williams, Ross W.; Gaffney, Amy M.

Here, age dating of nuclear material can provide insight into source and suspected use in nuclear forensic investigations. We report here a method for the determination of the date of most recent chemical purification for uranium materials using the 235U- 231Pa chronometer. Protactinium is separated from uranium and neptunium matrices using anion exchange resin, followed by sorption of Pa to an SiO 2 medium. The concentration of 231Pa is measured by isotope dilution mass spectrometry using 233Pa spikes prepared from an aliquot of 237Np and calibrated in-house using the rock standard Table Mountain Latite and the uranium isotopic standard U100.more » Combined uncertainties of age dates using this method are 1.5 to 3.5 %, an improvement over alpha spectrometry measurement methods. Model ages of five uranium standard reference materials are presented; all standards have concordant 235U- 231Pa and 234U- 230Th model ages.« less

Endometrial stem cell differentiation into smooth muscle cell: a novel approach for bladder tissue engineering in women.

PubMed

Shoae-Hassani, Alireza; Sharif, Shiva; Seifalian, Alexander M; Mortazavi-Tabatabaei, Seyed Abdolreza; Rezaie, Sassan; Verdi, Javad

2013-10-01

To investigate manufacturing smooth muscle cells (SMCs) for regenerative bladder reconstruction from differentiation of endometrial stem cells (EnSCs), as the recent discovery of EnSCs from the lining of women's uteri, opens up the possibility of using these cells for tissue engineering applications, such as building up natural tissue to repair prolapsed pelvic floors as well as building urinary bladder wall. Human EnSCs that were positive for cluster of differentiation 146 (CD146), CD105 and CD90 were isolated and cultured in Dulbecco's modified Eagle/F12 medium supplemented with myogenic growth factors. The myogenic factors included: transforming growth factor β, platelet-derived growth factor, hepatocyte growth factor and vascular endothelial growth factor. Differentiated SMCs on bioabsorbable polyethylene-glycol and collagen hydrogels were checked for SMC markers by real-time reverse-transcriptase polymerase chain reaction (RT-PCR), western blot (WB) and immunocytochemistry (ICC) analyses. Histology confirmed the growth of SMCs in the hydrogel matrices. The myogenic growth factors decreased the proliferation rate of EnSCs, but they differentiated the human EnSCs into SMCs more efficiently on hydrogel matrices and expressed specific SMC markers including α-smooth muscle actin, desmin, vinculin and calponin in RT-PCR, WB and ICC experiments. The survival rate of cultures on the hydrogel-coated matrices was significantly higher than uncoated cultures. Human EnSCs were successfully differentiated into SMCs, using hydrogels as scaffold. EnSCs may be used for autologous bladder wall regeneration without any immunological complications in women. Currently work is in progress using bioabsorbable nanocomposite materials as EnSC scaffolds for developing urinary bladder wall tissue. © 2013 The Authors. BJU International © 2013 BJU International.

TRACTOGRAPHY DENSITY AND NETWORK MEASURES IN ALZHEIMER'S DISEASE.

PubMed

Prasad, Gautam; Nir, Talia M; Toga, Arthur W; Thompson, Paul M

2013-04-01

Brain connectivity declines in Alzheimer's disease (AD), both functionally and structurally. Connectivity maps and networks derived from diffusion-based tractography offer new ways to track disease progression and to understand how AD affects the brain. Here we set out to identify (1) which fiber network measures show greatest differences between AD patients and controls, and (2) how these effects depend on the density of fibers extracted by the tractography algorithm. We computed brain networks from diffusion-weighted images (DWI) of the brain, in 110 subjects (28 normal elderly, 56 with early and 11 with late mild cognitive impairment, and 15 with AD). We derived connectivity matrices and network topology measures, for each subject, from whole-brain tractography and cortical parcellations. We used an ODF lookup table to speed up fiber extraction, and to exploit the full information in the orientation distribution function (ODF). This made it feasible to compute high density connectivity maps. We used accelerated tractography to compute a large number of fibers to understand what effect fiber density has on network measures and in distinguishing different disease groups in our data. We focused on global efficiency, transitivity, path length, mean degree, density, modularity, small world, and assortativity measures computed from weighted and binary undirected connectivity matrices. Of all these measures, the mean nodal degree best distinguished diagnostic groups. High-density fiber matrices were most helpful for picking up the more subtle clinical differences, e.g. between mild cognitively impaired (MCI) and normals, or for distinguishing subtypes of MCI (early versus late). Care is needed in clinical analyses of brain connectivity, as the density of extracted fibers may affect how well a network measure can pick up differences between patients and controls.

Neurocognitive screening of lead-exposed andean adolescents and young adults.

PubMed

Counter, S Allen; Buchanan, Leo H; Ortega, Fernando

2009-01-01

This study was designed to assess the utility of two psychometric tests with putative minimal cultural bias for use in field screening of lead (Pb)-exposed Ecuadorian Andean workers. Specifically, the study evaluated the effectiveness in Pb-exposed adolescents and young adults of a nonverbal reasoning test standardized for younger children, and compared the findings with performance on a test of auditory memory. The Raven Coloured Progressive Matrices (RCPM) was used as a test of nonverbal intelligence, and the Digit Span subtest of the Wechsler IV intelligence scale was used to assess auditory memory/attention. The participants were 35 chronically Pb-exposed Pb-glazing workers, aged 12-21 yr. Blood lead (PbB) levels for the study group ranged from 3 to 86 microg/dl, with 65.7% of the group at and above 10 microg/dl. Zinc protoporphyrin heme ratios (ZPP/heme) ranged from 38 to 380 micromol/mol, with 57.1% of the participants showing abnormal ZPP/heme (>69 micromol/mol). ZPP/heme was significantly correlated with PbB levels, suggesting chronic Pb exposure. Performance on the RCPM was less than average on the U.S., British, and Puerto Rican norms, but average on the Peruvian norms. Significant inverse associations between PbB/ZPP concentrations and RCPM standard scores using the U.S., Puerto Rican, and Peruvian norms were observed, indicating decreasing RCPM test performance with increasing PbB and ZPP levels. RCPM scores were significantly correlated with performance on the Digit Span test for auditory memory. Mean Digit Span scale score was less than average, suggesting auditory memory/attention deficits. In conclusion, both the RCPM and Digit Span tests were found to be effective instruments for field screening of visual-spatial reasoning and auditory memory abilities, respectively, in Pb-exposed Andean adolescents and young adults.

Use of job-exposure matrices to estimate occupational exposure to pesticides: A review.

PubMed

Carles, Camille; Bouvier, Ghislaine; Lebailly, Pierre; Baldi, Isabelle

2017-03-01

The health effects of pesticides have been extensively studied in epidemiology, mainly in agricultural populations. However, pesticide exposure assessment remains a key methodological issue for epidemiological studies. Besides self-reported information, expert assessment or metrology, job-exposure matrices still appear to be an interesting tool. We reviewed all existing matrices assessing occupational exposure to pesticides in epidemiological studies and described the exposure parameters they included. We identified two types of matrices, (i) generic ones that are generally used in case-control studies and document broad categories of pesticides in a large range of jobs, and (ii) specific matrices, developed for use in agricultural cohorts, that generally provide exposure metrics at the active ingredient level. The various applications of these matrices in epidemiological studies have proven that they are valuable tools to assess pesticide exposure. Specific matrices are particularly promising for use in agricultural cohorts. However, results obtained with matrices have rarely been compared with those obtained with other tools. In addition, the external validity of the given estimates has not been adequately discussed. Yet, matrices would help in reducing misclassification and in quantifying cumulated exposures, to improve knowledge about the chronic health effects of pesticides.

Stochastic local operations and classical communication (SLOCC) and local unitary operations (LU) classifications of n qubits via ranks and singular values of the spin-flipping matrices

NASA Astrophysics Data System (ADS)

Li, Dafa

2018-06-01

We construct ℓ -spin-flipping matrices from the coefficient matrices of pure states of n qubits and show that the ℓ -spin-flipping matrices are congruent and unitary congruent whenever two pure states of n qubits are SLOCC and LU equivalent, respectively. The congruence implies the invariance of ranks of the ℓ -spin-flipping matrices under SLOCC and then permits a reduction of SLOCC classification of n qubits to calculation of ranks of the ℓ -spin-flipping matrices. The unitary congruence implies the invariance of singular values of the ℓ -spin-flipping matrices under LU and then permits a reduction of LU classification of n qubits to calculation of singular values of the ℓ -spin-flipping matrices. Furthermore, we show that the invariance of singular values of the ℓ -spin-flipping matrices Ω 1^{(n)} implies the invariance of the concurrence for even n qubits and the invariance of the n-tangle for odd n qubits. Thus, the concurrence and the n-tangle can be used for LU classification and computing the concurrence and the n-tangle only performs additions and multiplications of coefficients of states.

Statistical similarity measures for link prediction in heterogeneous complex networks

NASA Astrophysics Data System (ADS)

Shakibian, Hadi; Charkari, Nasrollah Moghadam

2018-07-01

The majority of the link prediction measures in heterogeneous complex networks rely on the nodes connectivities while less attention has been paid to the importance of the nodes and paths. In this paper, we propose some new meta-path based statistical similarity measures to properly perform link prediction task. The main idea in the proposed measures is to drive some co-occurrence events in a number of co-occurrence matrices that are occurred between the visited nodes obeying a meta-path. The extracted co-occurrence matrices are analyzed in terms of the energy, inertia, local homogeneity, correlation, and information measure of correlation to determine various information theoretic measures. We evaluate the proposed measures, denoted as link energy, link inertia, link local homogeneity, link correlation, and link information measure of correlation, using a standard DBLP network data set. The results of the AUC score and Precision rate indicate the validity and accuracy of the proposed measures in comparison to the popular meta-path based similarity measures.

On polynomial preconditioning for indefinite Hermitian matrices

NASA Technical Reports Server (NTRS)

Freund, Roland W.

1989-01-01

The minimal residual method is studied combined with polynomial preconditioning for solving large linear systems (Ax = b) with indefinite Hermitian coefficient matrices (A). The standard approach for choosing the polynomial preconditioners leads to preconditioned systems which are positive definite. Here, a different strategy is studied which leaves the preconditioned coefficient matrix indefinite. More precisely, the polynomial preconditioner is designed to cluster the positive, resp. negative eigenvalues of A around 1, resp. around some negative constant. In particular, it is shown that such indefinite polynomial preconditioners can be obtained as the optimal solutions of a certain two parameter family of Chebyshev approximation problems. Some basic results are established for these approximation problems and a Remez type algorithm is sketched for their numerical solution. The problem of selecting the parameters such that the resulting indefinite polynomial preconditioners speeds up the convergence of minimal residual method optimally is also addressed. An approach is proposed based on the concept of asymptotic convergence factors. Finally, some numerical examples of indefinite polynomial preconditioners are given.

Development of a model of space station solar array

NASA Technical Reports Server (NTRS)

Bosela, Paul A.

1990-01-01

Space structures, such as the space station solar arrays, must be extremely lightweight, flexible structures. Accurate prediction of the natural frequencies and mode shapes is essential for determining the structural adequacy of components, and designing a control system. The tension preload in the blanket of photovoltaic solar collectors, and the free/free boundary conditions of a structure in space, causes serious reservations on the use of standard finite element techniques of solution. In particular, a phenomena known as grounding, or false stiffening, of the stiffness matrix occurs during rigid body rotation. The grounding phenomena is examined in detail. Numerous stiffness matrices developed by others are examined for rigid body rotation capability, and found lacking. Various techniques are used for developing new stiffness matrices from the rigorous solutions of the differential equations, including the solution of the directed force problem. A new directed force stiffness matrix developed by the author provides all the rigid body capabilities for the beam in space.

Determination of Fosetyl and Phosphonic Acid at 0.010 mg/kg Level by Ion Chromatography Tandem Mass Spectrometry.

PubMed

Bauer, Anna; Luetjohann, Jens; Rohn, Sascha; Kuballa, Juergen; Jantzen, Eckard

2018-01-10

A new sensitive, fast, and robust method using ion chromatography tandem mass spectrometry (IC-MS/MS) for the determination of fosetyl and phosphonic acid in plant-derived matrices was developed. For compensation of matrix effects and differences in recovery rates the isotopically labeled internal standard (ILIS) 18 O 3 -labeled phosphonic acid was added to the samples prior to the extraction of the target compounds. The validation of the method for the matrices tomato, apple, lemon, sultana, avocado, and wheat was performed according to the actual EU guidance document SANTE/11945/2015. The precision and accuracy were determined in five replicates at spiking levels of 0.010 and 0.100 mg/kg with recovery rates between 76 and 105% and RSDs between 1.2 and 17.8%. In this paper, it was achieved for the first time to detect both fosetyl and phosphonic acid at the reporting level of 0.010 mg/kg most relevant for organic plant food commodities.

Insights from Classifying Visual Concepts with Multiple Kernel Learning

PubMed Central

Binder, Alexander; Nakajima, Shinichi; Kloft, Marius; Müller, Christina; Samek, Wojciech; Brefeld, Ulf; Müller, Klaus-Robert; Kawanabe, Motoaki

2012-01-01

Combining information from various image features has become a standard technique in concept recognition tasks. However, the optimal way of fusing the resulting kernel functions is usually unknown in practical applications. Multiple kernel learning (MKL) techniques allow to determine an optimal linear combination of such similarity matrices. Classical approaches to MKL promote sparse mixtures. Unfortunately, 1-norm regularized MKL variants are often observed to be outperformed by an unweighted sum kernel. The main contributions of this paper are the following: we apply a recently developed non-sparse MKL variant to state-of-the-art concept recognition tasks from the application domain of computer vision. We provide insights on benefits and limits of non-sparse MKL and compare it against its direct competitors, the sum-kernel SVM and sparse MKL. We report empirical results for the PASCAL VOC 2009 Classification and ImageCLEF2010 Photo Annotation challenge data sets. Data sets (kernel matrices) as well as further information are available at http://doc.ml.tu-berlin.de/image_mkl/(Accessed 2012 Jun 25). PMID:22936970

Use of Massive Parallel Computing Libraries in the Context of Global Gravity Field Determination from Satellite Data

NASA Astrophysics Data System (ADS)

Brockmann, J. M.; Schuh, W.-D.

2011-07-01

The estimation of the global Earth's gravity field parametrized as a finite spherical harmonic series is computationally demanding. The computational effort depends on the one hand on the maximal resolution of the spherical harmonic expansion (i.e. the number of parameters to be estimated) and on the other hand on the number of observations (which are several millions for e.g. observations from the GOCE satellite missions). To circumvent these restrictions, a massive parallel software based on high-performance computing (HPC) libraries as ScaLAPACK, PBLAS and BLACS was designed in the context of GOCE HPF WP6000 and the GOCO consortium. A prerequisite for the use of these libraries is that all matrices are block-cyclic distributed on a processor grid comprised by a large number of (distributed memory) computers. Using this set of standard HPC libraries has the benefit that once the matrices are distributed across the computer cluster, a huge set of efficient and highly scalable linear algebra operations can be used.

Ethylene vinyl acetate based radiation grafted hydrophilic matrices: Process parameter standardization, grafting kinetics and characterization

NASA Astrophysics Data System (ADS)

Chaudhari, C. V.; Mondal, R. K.; Dubey, K. A.; Grover, V.; Panicker, L.; Bhardwaj, Y. K.; Varshney, L.

2016-08-01

A transparent, elastomeric, grafted matrix for several potential applications was synthesized by single-step simultaneous radiation grafting of methacrylic acid onto ethylene vinyl acetate (EVA). CuSO4 was found to be the most suitable homo-polymerization inhibitor among different inhibitors tried. The grafting kinetics was found to be a strong function of dose rate (D) and monomer content (M) and an equation relating grafting rate Rg=Kg [M]1.13D0.23 was deduced. Crystallinity of the grafted matrices as assessed from XRD and DSC measurements indicated decrease in crystalline content with increase in grafting yield, suggesting crystalline domain of EVA get disrupted on grafting. Elastic modulus increased linearly with the increase in grafting yield, though elongation at break decreased precipitously from 900% to 30% at even 9% grafting. Thermo-gravimetric analysis showed three step weight loss of the grafted EVA matrix. The grafting of MAA resulted in increase in surface energy mainly due to enhanced polar component.

Matrix computations in MACSYMA

NASA Technical Reports Server (NTRS)

Wang, P. S.

1977-01-01

Facilities built into MACSYMA for manipulating matrices with numeric or symbolic entries are described. Computations will be done exactly, keeping symbols as symbols. Topics discussed include how to form a matrix and create other matrices by transforming existing matrices within MACSYMA; arithmetic and other computation with matrices; and user control of computational processes through the use of optional variables. Two algorithms designed for sparse matrices are given. The computing times of several different ways to compute the determinant of a matrix are compared.

Complex symmetric matrices with strongly stable iterates

NASA Technical Reports Server (NTRS)

Tadmor, E.

1985-01-01

Complex-valued symmetric matrices are studied. A simple expression for the spectral norm of such matrices is obtained, by utilizing a unitarily congruent invariant form. A sharp criterion is provided for identifying those symmetric matrices whose spectral norm is not exceeding one: such strongly stable matrices are usually sought in connection with convergent difference approximations to partial differential equations. As an example, the derived criterion is applied to conclude the strong stability of a Lax-Wendroff scheme.

Poetry as Progress: Balancing Standards-Based Reforms with Aesthetic Inquiry

ERIC Educational Resources Information Center

Liu, Laura B.

2011-01-01

The meaning of "progress" in U.S. educational institutions has undergone much debate (Tyack & Cuban, 1995). Standards-driven practices have often promoted a search for "right" answers in place of critical and diverse thinking. Globalization and its impacts compel us to continue revising and articulating the meaning of progress for 21st century…

Calculation of controllability and observability matrices for special case of continuous-time multi-order fractional systems.

PubMed

Hassanzadeh, Iman; Tabatabaei, Mohammad

2017-03-28

In this paper, controllability and observability matrices for pseudo upper or lower triangular multi-order fractional systems are derived. It is demonstrated that these systems are controllable and observable if and only if their controllability and observability matrices are full rank. In other words, the rank of these matrices should be equal to the inner dimension of their corresponding state space realizations. To reduce the computational complexities, these matrices are converted to simplified matrices with smaller dimensions. Numerical examples are provided to show the usefulness of the mentioned matrices for controllability and observability analysis of this case of multi-order fractional systems. These examples clarify that the duality concept is not necessarily true for these special systems. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

An Object-Oriented Collection of Minimum Degree Algorithms: Design, Implementation, and Experiences

NASA Technical Reports Server (NTRS)

Kumfert, Gary; Pothen, Alex

1999-01-01

The multiple minimum degree (MMD) algorithm and its variants have enjoyed 20+ years of research and progress in generating fill-reducing orderings for sparse, symmetric positive definite matrices. Although conceptually simple, efficient implementations of these algorithms are deceptively complex and highly specialized. In this case study, we present an object-oriented library that implements several recent minimum degree-like algorithms. We discuss how object-oriented design forces us to decompose these algorithms in a different manner than earlier codes and demonstrate how this impacts the flexibility and efficiency of our C++ implementation. We compare the performance of our code against other implementations in C or Fortran.

Proactive interference and item similarity in working memory.

PubMed

Bunting, Michael

2006-03-01

Proactive interference (PI) may influence the predictive utility of working memory span tasks. Participants in one experiment (N=70) completed Ravens Advanced Progressive Matrices (RAPM) and multiple versions of operation span and probed recall, modified for the type of memoranda (digits or words). Changing memoranda within- or across-trials released PI, but not doing so permitted PI buildup. Scores from PI-build trials, but not PI-release trials, correlated with RAPM and accounted for as much variance in RAPM as unmodified tasks. These results are consistent with controlled attention and inhibition accounts of working memory, and they elucidate a fundamental component of working memory span tasks.

Thinking in Pictures as a cognitive account of autism.

PubMed

Kunda, Maithilee; Goel, Ashok K

2011-09-01

We analyze the hypothesis that some individuals on the autism spectrum may use visual mental representations and processes to perform certain tasks that typically developing individuals perform verbally. We present a framework for interpreting empirical evidence related to this "Thinking in Pictures" hypothesis and then provide comprehensive reviews of data from several different cognitive tasks, including the n-back task, serial recall, dual task studies, Raven's Progressive Matrices, semantic processing, false belief tasks, visual search, spatial recall, and visual recall. We also discuss the relationships between the Thinking in Pictures hypothesis and other cognitive theories of autism including Mindblindness, Executive Dysfunction, Weak Central Coherence, and Enhanced Perceptual Functioning.

Array Biosensor for Toxin Detection: Continued Advances

PubMed Central

Taitt, Chris Rowe; Shriver-Lake, Lisa C.; Ngundi, Miriam M.; Ligler, Frances S.

2008-01-01

The following review focuses on progress made in the last five years with the NRL Array Biosensor, a portable instrument for rapid and simultaneous detection of multiple targets. Since 2003, the Array Biosensor has been automated and miniaturized for operation at the point-of-use. The Array Biosensor has also been used to demonstrate (1) quantitative immunoassays against an expanded number of toxins and toxin indicators in food and clinical fluids, and (2) the efficacy of semi-selective molecules as alternative recognition moieties. Blind trials, with unknown samples in a variety of matrices, have demonstrated the versatility, sensitivity, and reliability of the automated system. PMID:27873991

Reduction of matrix interferences in furnace atomic absorption with the L'vov Platform

USGS Publications Warehouse

Kaiser, M.L.; Koirtyohann, S.R.; Hinderberger, E.J.; Taylor, Howard E.

1981-01-01

Use of a modified L'vov Platform and ammonium phosphate as a matrix modifier greatly reduced matrix interferences in a commercial Massmann-type atomic absorption furnace. Platforms were readily fabricated from furnace tubes and, once positioned in the furnace, caused no inconvenience in operation. Two volatile elements (Pb, Cd), two of intermediate volatility (Co, Cr) and two which form stable oxides (Al, Sn) were tested in natural water and selected synthetic matrices. In every case for which there was a significant matrix effect during atomization from the tube wall, the platform and platform plus modifier gave improved performance. With lead, for example, an average ratio of 0.48 ?? 0.11 was found when the slope of the standard additions plot for six different natural water samples was compared to the slope of the standard working curve in dilute acid. The average slope ratio between the natural water matrices and the dilute acid matrix was 0.94 ?? 0.03 with the L'vov Platform and 0.96 ?? 0.03 with the platform and matrix modifier. In none of the cases studied did the use of the platform or platform plus modifier cause an interference problem where none existed while atomizing from the tube wall. An additional benefit of the platform was a factor of about two improvement in peak height precision. ?? 1981.

Performance Assessment of Different Pulse Reconstruction Algorithms for the ATHENA X-Ray Integral Field Unit

NASA Technical Reports Server (NTRS)

Peille, Phillip; Ceballos, Maria Teresa; Cobo, Beatriz; Wilms, Joern; Bandler, Simon; Smith, Stephen J.; Dauser, Thomas; Brand, Thorsten; Den Haretog, Roland; de Plaa, Jelle;

Almost commuting self-adjoint matrices: The real and self-dual cases

NASA Astrophysics Data System (ADS)

Loring, Terry A.; Sørensen, Adam P. W.

2016-08-01

We show that a pair of almost commuting self-adjoint, symmetric matrices is close to a pair of commuting self-adjoint, symmetric matrices (in a uniform way). Moreover, we prove that the same holds with self-dual in place of symmetric and also for paths of self-adjoint matrices. Since a symmetric, self-adjoint matrix is real, we get a real version of Huaxin Lin’s famous theorem on almost commuting matrices. Similarly, the self-dual case gives a version for matrices over the quaternions. To prove these results, we develop a theory of semiprojectivity for real C*-algebras and also examine various definitions of low-rank for real C*-algebras.

Quantitative aspects of inductively coupled plasma mass spectrometry

NASA Astrophysics Data System (ADS)

Bulska, Ewa; Wagner, Barbara

2016-10-01

Accurate determination of elements in various kinds of samples is essential for many areas, including environmental science, medicine, as well as industry. Inductively coupled plasma mass spectrometry (ICP-MS) is a powerful tool enabling multi-elemental analysis of numerous matrices with high sensitivity and good precision. Various calibration approaches can be used to perform accurate quantitative measurements by ICP-MS. They include the use of pure standards, matrix-matched standards, or relevant certified reference materials, assuring traceability of the reported results. This review critically evaluates the advantages and limitations of different calibration approaches, which are used in quantitative analyses by ICP-MS. Examples of such analyses are provided. This article is part of the themed issue 'Quantitative mass spectrometry'.

Renormalization group invariant of lepton Yukawa couplings

NASA Astrophysics Data System (ADS)

Tsuyuki, Takanao

2015-04-01

By using quark Yukawa matrices only, we can construct renormalization invariants that are exact at the one-loop level in the standard model. One of them, Iq, is accidentally consistent with unity, even though quark masses are strongly hierarchical. We calculate a lepton version of the invariant Il for Dirac and Majorana neutrino cases and find that Il can also be close to unity. For the Dirac neutrino and inverted hierarchy case, if the lightest neutrino mass is 3.0 meV to 8.8 meV, an equality Iq=Il can be satisfied. These invariants are not changed even if new particles couple to the standard model particles, as long as those couplings are generation independent.

Decision Matrices: Tools to Enhance Middle School Engineering Instruction

ERIC Educational Resources Information Center

Gonczi, Amanda L.; Bergman, Brenda G.; Huntoon, Jackie; Allen, Robin; McIntyre, Barb; Turner, Sheri; Davis, Jen; Handler, Rob

2017-01-01

Decision matrices are valuable engineering tools. They allow engineers to objectively examine solution options. Decision matrices can be incorporated in K-12 classrooms to support authentic engineering instruction. In this article we provide examples of how decision matrices have been incorporated into 6th and 7th grade classrooms as part of an…

19 CFR 10.90 - Master records and metal matrices.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 19 Customs Duties 1 2011-04-01 2011-04-01 false Master records and metal matrices. 10.90 Section... Master Records, and Metal Matrices § 10.90 Master records and metal matrices. (a) Consumption entries... made, of each master record or metal matrix covered thereby. (c) A bond on Customs Form 301, containing...

19 CFR 10.90 - Master records and metal matrices.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 19 Customs Duties 1 2013-04-01 2013-04-01 false Master records and metal matrices. 10.90 Section... Master Records, and Metal Matrices § 10.90 Master records and metal matrices. (a) Consumption entries... made, of each master record or metal matrix covered thereby. (c) A bond on Customs Form 301, containing...

19 CFR 10.90 - Master records and metal matrices.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 19 Customs Duties 1 2014-04-01 2014-04-01 false Master records and metal matrices. 10.90 Section... Master Records, and Metal Matrices § 10.90 Master records and metal matrices. (a) Consumption entries... made, of each master record or metal matrix covered thereby. (c) A bond on Customs Form 301, containing...

19 CFR 10.90 - Master records and metal matrices.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 19 Customs Duties 1 2012-04-01 2012-04-01 false Master records and metal matrices. 10.90 Section... Master Records, and Metal Matrices § 10.90 Master records and metal matrices. (a) Consumption entries... made, of each master record or metal matrix covered thereby. (c) A bond on Customs Form 301, containing...

19 CFR 10.90 - Master records and metal matrices.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 19 Customs Duties 1 2010-04-01 2010-04-01 false Master records and metal matrices. 10.90 Section... Master Records, and Metal Matrices § 10.90 Master records and metal matrices. (a) Consumption entries... made, of each master record or metal matrix covered thereby. (c) A bond on Customs Form 301, containing...

Crosslinked type II collagen matrices: preparation, characterization, and potential for cartilage engineering.

PubMed

Pieper, J S; van der Kraan, P M; Hafmans, T; Kamp, J; Buma, P; van Susante, J L C; van den Berg, W B; Veerkamp, J H; van Kuppevelt, T H

2002-08-01

The limited intrinsic repair capacity of articular cartilage has stimulated continuing efforts to develop tissue engineered analogues. Matrices composed of type II collagen and chondroitin sulfate (CS), the major constituents of hyaline cartilage, may create an appropriate environment for the generation of cartilage-like tissue. In this study, we prepared, characterized, and evaluated type 11 collagen matrices with and without CS. Type II collagen matrices were prepared using purified, pepsin-treated, type II collagen. Techniques applied to prepare type I collagen matrices were found unsuitable for type II collagen. Crosslinking of collagen and covalent attachment of CS was performed using 1-ethyl-3-(3-dimethyl aminopropyl)carbodiimide. Porous matrices were prepared by freezing and lyophilization, and their physico-chemical characteristics (degree of crosslinking, denaturing temperature, collagenase-resistance, amount of CS incorporated) established. Matrices were evaluated for their capacity to sustain chondrocyte proliferation and differentiation in vitro. After 7 d of culture, chondrocytes were mainly located at the periphery of the matrices. In contrast to type I collagen, type II collagen supported the distribution of cells throughout the matrix. After 14 d of culture, matrices were surfaced with a cartilagenous-like layer, and occasionally clusters of chondrocytes were present inside the matrix. Chondrocytes proliferated and differentiated as indicated by biochemical analyses, ultrastructural observations, and reverse transcriptase PCR for collagen types I, II and X. No major differences were observed with respect to the presence or absence of CS in the matrices.

The similar effects of verbal and non-verbal intervening tasks on word recall in an elderly population.

PubMed

Williams, B R; Sullivan, S K; Morra, L F; Williams, J R; Donovick, P J

2014-01-01

Vulnerability to retroactive interference has been shown to increase with cognitive aging. Consistent with the findings of memory and aging literature, the authors of the California Verbal Learning Test-II (CVLT-II) suggest that a non-verbal task be administered during the test's delay interval to minimize the effects of retroactive interference on delayed recall. The goal of the present study was to determine the extent to which retroactive interference caused by non-verbal and verbal intervening tasks affects recall of verbal information in non-demented, older adults. The effects of retroactive interference on recall of words during Long-Delay recall on the California Verbal Learning Test-II (CVLT-II) were evaluated. Participants included 85 adults age 60 and older. During a 20-minute delay interval on the CVLT-II, participants received either a verbal (WAIS-III Vocabulary or Peabody Picture Vocabulary Test-IIIB) or non-verbal (Raven's Standard Progressive Matrices or WAIS-III Block Design) intervening task. Similarly to previous research with young adults (Williams & Donovick, 2008), older adults recalled the same number of words across all groups, regardless of the type of intervening task. These findings suggest that the administration of verbal intervening tasks during the CVLT-II do not elicit more retroactive interference than non-verbal intervening tasks, and thus verbal tasks need not be avoided during the delay interval of the CVLT-II.

Visual Working Memory Capacity Can Be Increased by Training on Distractor Filtering Efficiency.

PubMed

Li, Cui-Hong; He, Xu; Wang, Yu-Juan; Hu, Zhe; Guo, Chun-Yan

2017-01-01

It is generally considered that working memory (WM) capacity is limited and that WM capacity affects cognitive processes. Distractor filtering efficiency has been suggested to be an important factor in determining the visual working memory (VWM) capacity of individuals. In the present study, we investigated whether training in visual filtering efficiency (FE) could improve VWM capacity, as measured by performance on the change detection task (CDT) and changes of contralateral delay activity (CDA) (contralateral delay activity) of different conditions, and evaluated the transfer effect of visual FE training on verbal WM and fluid intelligence, as indexed by performance on the verbal WM span task and Raven's Standard Progressive Matrices (RSPM) test, respectively. Participants were divided into high- and low-capacity groups based on their performance in a CDT designed to test VWM capacity, and then the low-capacity individuals received 20 days of FE training. The training significantly improved the group's performance in the CDT, and their CDA models of different conditions became more similar with high capacity group, and the effect generalized to improve verbal WM span. These gains were maintained at a 3-month follow-up test. Participants' RSPM scores were not changed by the training. These findings support the notion that WM capacity is determined, at least in part, by distractor FE and can be enhanced through training.

Impairments in proverb interpretation following focal frontal lobe lesions☆

PubMed Central

Murphy, Patrick; Shallice, Tim; Robinson, Gail; MacPherson, Sarah E.; Turner, Martha; Woollett, Katherine; Bozzali, Marco; Cipolotti, Lisa

2013-01-01

The proverb interpretation task (PIT) is often used in clinical settings to evaluate frontal “executive” dysfunction. However, only a relatively small number of studies have investigated the relationship between frontal lobe lesions and performance on the PIT. We compared 52 patients with unselected focal frontal lobe lesions with 52 closely matched healthy controls on a proverb interpretation task. Participants also completed a battery of neuropsychological tests, including a fluid intelligence task (Raven’s Advanced Progressive Matrices). Lesions were firstly analysed according to a standard left/right sub-division. Secondly, a finer-grained analysis compared the performance of patients with medial, left lateral and right lateral lesions with healthy controls. Thirdly, a contrast of specific frontal subgroups compared the performance of patients with medial lesions with patients with lateral frontal lesions. The results showed that patients with left frontal lesions were significantly impaired on the PIT, while in patients with right frontal lesions the impairments approached significance. Medial frontal patients were the only frontal subgroup impaired on the PIT, relative to healthy controls and lateral frontal patients. Interestingly, an error analysis indicated that a significantly higher number of concrete responses were found in the left lateral subgroup compared to healthy controls. We found no correlation between scores on the PIT and on the fluid intelligence task. Overall our results suggest that specific regions of the frontal lobes contribute to the performance on the PIT. PMID:23850600

Factors associated with poor academic achievement among urban primary school children in Malaysia.

PubMed

Ong, L C; Chandran, V; Lim, Y Y; Chen, A H; Poh, B K

2010-03-01

The aim of this study was to identify factors associated with poor academic achievement during the early school years. This was a cross-sectional study of urban Primary Two children. Sociodemographic and medical data were obtained from questionnaires and interviews. Achievement was based on marks obtained in the core subjects of the Primary One examination. All students underwent the Raven's Standard Progressive Matrices test as a general measure of cognitive ability, audiometry and visual tests, and standardised measurements of weight and height. Out of 1,470 eligible children, 206 (14 percent) had poor academic achievement. Of the 919 children who participated in the study, 111 (12.1 percent) had poor achievement compared with 95 (17.2 percent) of the 551 non-participants. Using logistic regression analysis, the factors that were found to be independently associated with poor academic achievement were lower mean Raven scores (p-value is less than 0.001), lower mean socioeconomic status scores (p-value is less than 0.001), larger sibship size (p-value is 0.031), male gender (odds ratio [OR] 1.7; 95 percent confidence interval [CI] 1.1-2.65) and a history of prematurity (OR 14; 95 percent CI 2-97.8). Cognitive ability, gender, prematurity and social factors contribute to poor academic achievement during the early school years. The higher proportion of poor achievers among non-participants warrants further attention.

The use of comet assay in plant toxicology: recent advances

PubMed Central

Santos, Conceição L. V.; Pourrut, Bertrand; Ferreira de Oliveira, José M. P.

2015-01-01

The systematic study of genotoxicity in plants induced by contaminants and other stress agents has been hindered to date by the lack of reliable and robust biomarkers. The comet assay is a versatile and sensitive method for the evaluation of DNA damages and DNA repair capacity at single-cell level. Due to its simplicity and sensitivity, and the small number of cells required to obtain robust results, the use of plant comet assay has drastically increased in the last decade. For years its use was restricted to a few model species, e.g., Allium cepa, Nicotiana tabacum, Vicia faba, or Arabidopsis thaliana but this number largely increased in the last years. Plant comet assay has been used to study the genotoxic impact of radiation, chemicals including pesticides, phytocompounds, heavy metals, nanoparticles or contaminated complex matrices. Here we will review the most recent data on the use of this technique as a standard approach for studying the genotoxic effects of different stress conditions on plants. Also, we will discuss the integration of information provided by the comet assay with other DNA-damage indicators, and with cellular responses including oxidative stress, cell division or cell death. Finally, we will focus on putative relations between transcripts related with DNA damage pathways, DNA replication and repair, oxidative stress and cell cycle progression that have been identified in plant cells with comet assays demonstrating DNA damage. PMID:26175750

Matrices. New Topics for Secondary School Mathematics: Materials and Software.

ERIC Educational Resources Information Center

North Carolina School of Science and Mathematics. Dept. of Mathematics and Computer Science.

This material on matrices is part of "Introduction to College Mathematics" (ICM), designed to prepare high school students who have students who have completed algebra II for the variety of mathematics they will encounter in college and beyond. The concept goals of this unit are to use matrices to model real-world phenomena, to use matrices as…

Generalized matrix summability of a conjugate derived Fourier series.

PubMed

Mursaleen, M; Alotaibi, Abdullah

2017-01-01

The study of infinite matrices is important in the theory of summability and in approximation. In particular, Toeplitz matrices or regular matrices and almost regular matrices have been very useful in this context. In this paper, we propose to use a more general matrix method to obtain necessary and sufficient conditions to sum the conjugate derived Fourier series.

Rhotrix Vector Spaces

ERIC Educational Resources Information Center

Aminu, Abdulhadi

2010-01-01

By rhotrix we understand an object that lies in some way between (n x n)-dimensional matrices and (2n - 1) x (2n - 1)-dimensional matrices. Representation of vectors in rhotrices is different from the representation of vectors in matrices. A number of vector spaces in matrices and their properties are known. On the other hand, little seems to be…

Commutative semigroups of real and complex matrices. [with use of the jordan form

NASA Technical Reports Server (NTRS)

Brown, D. R.

1974-01-01

The computation of divergence is studied. Covariance matrices to be analyzed admit a common diagonalization, or even triangulation. Sufficient conditions are given for such phenomena to take place, the arguments cover both real and complex matrices, and are not restricted to Hermotian or other special forms. Specifically, it is shown to be sufficient that the matrices in question commute in order to admit a common triangulation. Several results hold in the case that the matrices in question form a closed and bounded set, rather than only in the finite case.

Field matric potential sensor

DOEpatents

Hubbell, Joel M.; Sisson, James B.

2001-01-01

A method of determining matric potential of a sample, the method comprising placing the sample in a container, the container having an opening; and contacting the sample with a tensiometer via the opening. An apparatus for determining matric potential of a sample, the apparatus comprising a housing configured to receive a sample; a portable matric potential sensing device extending into the housing and having a porous member; and a wall closing the housing to insulate the sample and at least a portion of the matric potential sensing device including the porous member.

Production of Human Pluripotent Stem Cell Therapeutics Under Defined Xeno-free Conditions: Progress and Challenges

PubMed Central

Fan, Yongjia; Wu, Jincheng; Ashok, Preeti; Hsiung, Michael; Tzanakakis, Emmanuel S.

2014-01-01

Recent advances on human pluripotent stem cells (hPSCs), including human embryonic stem cells (hESCs) and induced pluripotent stem cells (hiPSCs) have brought us closer to the realization of their clinical potential. Nonetheless, tissue engineering and regenerative medicine applications will require the generation of hPSC products well beyond the laboratory scale. This also mandates the production of hPSC therapeutics in fully-defined, xeno-free systems and in a reproducible manner. Toward this goal, we summarize current developments in defined media free of animal-derived components for hPSC culture. Bioinspired and synthetic extracellular matrices for the attachment growth and differentiation of hPSCs are also reviewed. Given that most progress in xeno-free medium and substrate development has been demonstrated in two-dimensional rather than three dimensional culture systems, translation from the former to the latter poses unique difficulties. These challenges are discussed in the context of cultivation platforms of hPSCs as aggregates, on microcarriers or after encapsulation in biocompatible scaffolds. PMID:25077810

Fusion materials semiannual progress report for the period ending December 31, 1996

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

1997-04-01

This is the twenty-first in a series of semiannual technical progress reports on fusion materials. This report combines the full spectrum of research and development activities on both metallic and non-metallic materials with primary emphasis on the effects of the neutronic and chemical environment on the properties and performance of materials for in-vessel components. This effort forms one element of the materials program being conducted in support of the Fusion Energy Sciences Program of the US Department of Energy. The other major element of the program is concerned with the interactions between reactor materials and the plasma and is reportedmore » separately. The report covers the following topics: vanadium alloys; silicon carbide composite materials; ferritic/martensitic steels; copper alloys and high heat flux materials; austenitic stainless steels; insulating ceramics and optical materials; solid breeding materials; radiation effects, mechanistic studies and experimental methods; dosimetry, damage parameters, and activation calculations; materials engineering and design requirements; and irradiation facilities, test matrices, and experimental methods.« less

Production of human pluripotent stem cell therapeutics under defined xeno-free conditions: progress and challenges.

PubMed

Fan, Yongjia; Wu, Jincheng; Ashok, Preeti; Hsiung, Michael; Tzanakakis, Emmanuel S

2015-02-01

Recent advances on human pluripotent stem cells (hPSCs), including human embryonic stem cells (hESCs) and induced pluripotent stem cells (hiPSCs) have brought us closer to the realization of their clinical potential. Nonetheless, tissue engineering and regenerative medicine applications will require the generation of hPSC products well beyond the laboratory scale. This also mandates the production of hPSC therapeutics in fully-defined, xeno-free systems and in a reproducible manner. Toward this goal, we summarize current developments in defined media free of animal-derived components for hPSC culture. Bioinspired and synthetic extracellular matrices for the attachment, growth and differentiation of hPSCs are also reviewed. Given that most progress in xeno-free medium and substrate development has been demonstrated in two-dimensional rather than three dimensional culture systems, translation from the former to the latter poses unique difficulties. These challenges are discussed in the context of cultivation platforms of hPSCs as aggregates, on microcarriers or after encapsulation in biocompatible scaffolds.

CI chondrite-like clasts in the Nilpena polymict ureilite - Implications for aqueous alteration processes in CI chondrites

NASA Technical Reports Server (NTRS)

Brearley, Adrian J.; Prinz, Martin

1992-01-01

Petrographic studies of Nilpena polymict ureilite have revealed the presence of small quantities of carbonaceous chondrite matrix clasts. Detailed electron microprobe and TEM studies show that the chemistry and fine-scale mineralogy of one of these clasts is consistent with CI carbonaceous chondrite matrix. Compared to Orgeuil, the phyllosilicate, sulfide, and oxide mineralogy suggests that the Nilpena clasts may represent a less altered type of CI matrix. It is suggested that increased oxidation and aqueous alteration of Nilpena-type materials could result in the formation of the type of mineral assemblage observed in Orgueil. Increased alteration produces progressive more Mg-rich phyllosilicates and more Fe(3+)-rich iron oxides, such as ferrihydrite. As a function of increased alteration, Ca is also progressively leached from the matrix material to form carbonate veins. The depletion of Ca in CI chondrite matrices suggests the Ivuna and Alais may be intermediate in their degree of alteration to Nilpena and Orgueil.

Multi-class multi-residue analysis of veterinary drugs in meat using enhanced matrix removal lipid cleanup and liquid chromatography-tandem mass spectrometry.

PubMed

Zhao, Limian; Lucas, Derick; Long, David; Richter, Bruce; Stevens, Joan

2018-05-11

This study presents the development and validation of a quantitation method for the analysis of multi-class, multi-residue veterinary drugs using lipid removal cleanup cartridges, enhanced matrix removal lipid (EMR-Lipid), for different meat matrices by liquid chromatography tandem mass spectrometry detection. Meat samples were extracted using a two-step solid-liquid extraction followed by pass-through sample cleanup. The method was optimized based on the buffer and solvent composition, solvent additive additions, and EMR-Lipid cartridge cleanup. The developed method was then validated in five meat matrices, porcine muscle, bovine muscle, bovine liver, bovine kidney and chicken liver to evaluate the method performance characteristics, such as absolute recoveries and precision at three spiking levels, calibration curve linearity, limit of quantitation (LOQ) and matrix effect. The results showed that >90% of veterinary drug analytes achieved satisfactory recovery results of 60-120%. Over 97% analytes achieved excellent reproducibility results (relative standard deviation (RSD) < 20%), and the LOQs were 1-5 μg/kg in the evaluated meat matrices. The matrix co-extractive removal efficiency by weight provided by EMR-lipid cartridge cleanup was 42-58% in samples. The post column infusion study showed that the matrix ion suppression was reduced for samples with the EMR-Lipid cartridge cleanup. The reduced matrix ion suppression effect was also confirmed with <15% frequency of compounds with significant quantitative ion suppression (>30%) for all tested veterinary drugs in all of meat matrices. The results showed that the two-step solid-liquid extraction provides efficient extraction for the entire spectrum of veterinary drugs, including the difficult classes such as tetracyclines, beta-lactams etc. EMR-Lipid cartridges after extraction provided efficient sample cleanup with easy streamlined protocol and minimal impacts on analytes recovery, improving method reliability and consistency. Copyright © 2018 Elsevier B.V. All rights reserved.

Adaptive framework to better characterize errors of apriori fluxes and observational residuals in a Bayesian setup for the urban flux inversions.

NASA Astrophysics Data System (ADS)

Ghosh, S.; Lopez-Coto, I.; Prasad, K.; Karion, A.; Mueller, K.; Gourdji, S.; Martin, C.; Whetstone, J. R.

2017-12-01

The National Institute of Standards and Technology (NIST) supports the North-East Corridor Baltimore Washington (NEC-B/W) project and Indianapolis Flux Experiment (INFLUX) aiming to quantify sources of Greenhouse Gas (GHG) emissions as well as their uncertainties. These projects employ different flux estimation methods including top-down inversion approaches. The traditional Bayesian inversion method estimates emission distributions by updating prior information using atmospheric observations of Green House Gases (GHG) coupled to an atmospheric and dispersion model. The magnitude of the update is dependent upon the observed enhancement along with the assumed errors such as those associated with prior information and the atmospheric transport and dispersion model. These errors are specified within the inversion covariance matrices. The assumed structure and magnitude of the specified errors can have large impact on the emission estimates from the inversion. The main objective of this work is to build a data-adaptive model for these covariances matrices. We construct a synthetic data experiment using a Kalman Filter inversion framework (Lopez et al., 2017) employing different configurations of transport and dispersion model and an assumed prior. Unlike previous traditional Bayesian approaches, we estimate posterior emissions using regularized sample covariance matrices associated with prior errors to investigate whether the structure of the matrices help to better recover our hypothetical true emissions. To incorporate transport model error, we use ensemble of transport models combined with space-time analytical covariance to construct a covariance that accounts for errors in space and time. A Kalman Filter is then run using these covariances along with Maximum Likelihood Estimates (MLE) of the involved parameters. Preliminary results indicate that specifying sptio-temporally varying errors in the error covariances can improve the flux estimates and uncertainties. We also demonstrate that differences between the modeled and observed meteorology can be used to predict uncertainties associated with atmospheric transport and dispersion modeling which can help improve the skill of an inversion at urban scales.

Nanomaterials in consumer products: a challenging analytical problem.

PubMed

Contado, Catia

2015-01-01

Many products used in everyday life are made with the assistance of nanotechnologies. Cosmetic, pharmaceuticals, sunscreen, powdered food are only few examples of end products containing nano-sized particles (NPs), generally added to improve the product quality. To evaluate correctly benefits vs. risks of engineered nanomaterials and consequently to legislate in favor of consumer's protection, it is necessary to know the hazards connected with the exposure levels. This information implies transversal studies and a number of different competences. On analytical point of view the identification, quantification and characterization of NPs in food matrices and in cosmetic or personal care products pose significant challenges, because NPs are usually present at low concentration levels and the matrices, in which they are dispersed, are complexes and often incompatible with analytical instruments that would be required for their detection and characterization. This paper focused on some analytical techniques suitable for the detection, characterization and quantification of NPs in food and cosmetics products, reports their recent application in characterizing specific metal and metal-oxide NPs in these two important industrial and market sectors. The need of a characterization of the NPs as much as possible complete, matching complementary information about different metrics, possible achieved through validate procedures, is what clearly emerges from this research. More work should be done to produce standardized materials and to set-up methodologies to determine number-based size distributions and to get quantitative date about the NPs in such a complex matrices.

Tensiometers—Theory, construction, and use

USGS Publications Warehouse

Stannard, D.I.

1992-01-01

Standard tensiometers are used to measure matric potential as low as −870 cm of water in the unsaturated zone by creating a saturated hydraulic link between the soil water and a pressure sensor. The direction and, in some cases, quantity of water flux can be determined using multiple installations.A variety of commercial and fabricated tensiometers are commonly used. Saturated porous ceramic materials, which form an interface between the soil water and the bulk water inside the instrument, are available in many shapes, sizes, and pore diameters. A gage, manometer, or electronic pressure transducer is connected to the porous material with small- or large-diameter tubing. Selection of these components allows the user to optimize one or more characteristics, such as accuracy, versatility, response time, durability, maintenance, extent of data collection, and cost.Special designs have extended the normal capabilities of tensiometers, allowing measurement in cold or remote areas, measurement of matric potential as low as −153 m of water (−15 bars), measurement at depths as deep as 6 m (recorded at land surface), and automatic measurement using as many as 22 tensiometers connected to a single pressure transducer.Continuous hydraulic connection between the porous material and soil, and minimal disturbance of the natural infiltration pattern are necessary for successful installation. Avoidance of errors caused by air invasion, nonequilibrium of the instrument, or pressure-sensor inaccuracy will produce reliable values of matric potential, a first step in characterizing unsaturated flow.

Nanomaterials in consumer products: a challenging analytical problem

NASA Astrophysics Data System (ADS)

Contado, Catia

2015-08-01

Many products used in everyday life are made with the assistance of nanotechnologies. Cosmetic, pharmaceuticals, sunscreen, powdered food are only few examples of end products containing nano-sized particles (NPs), generally added to improve the product quality. To evaluate correctly benefits versus risks of engineered nanomaterials and consequently to legislate in favor of consumer’s protection, it is necessary to know the hazards connected with the exposure levels. This information implies transversal studies and a number of different competences. On analytical point of view the identification, quantification and characterization of NPs in food matrices and in cosmetic or personal care products pose significant challenges, because NPs are usually present at low concentration levels and the matrices, in which they are dispersed, are complexes and often incompatible with analytical instruments that would be required for their detection and characterization. This paper focused on some analytical techniques suitable for the detection, characterization and quantification of NPs in food and cosmetics products, reports their recent application in characterizing specific metal and metal-oxide NPs in these two important industrial and market sectors. The need of a characterization of the NPs as much as possible complete, matching complementary information about different metrics, possible achieved through validate procedures, is what clearly emerges from this research. More work should be done to produce standardized materials and to set-up methodologies to determine number-based size distributions and to get quantitative date about the NPs in such a complex matrices.

Structural damage detection based on stochastic subspace identification and statistical pattern recognition: I. Theory

NASA Astrophysics Data System (ADS)

Ren, W. X.; Lin, Y. Q.; Fang, S. E.

2011-11-01

One of the key issues in vibration-based structural health monitoring is to extract the damage-sensitive but environment-insensitive features from sampled dynamic response measurements and to carry out the statistical analysis of these features for structural damage detection. A new damage feature is proposed in this paper by using the system matrices of the forward innovation model based on the covariance-driven stochastic subspace identification of a vibrating system. To overcome the variations of the system matrices, a non-singularity transposition matrix is introduced so that the system matrices are normalized to their standard forms. For reducing the effects of modeling errors, noise and environmental variations on measured structural responses, a statistical pattern recognition paradigm is incorporated into the proposed method. The Mahalanobis and Euclidean distance decision functions of the damage feature vector are adopted by defining a statistics-based damage index. The proposed structural damage detection method is verified against one numerical signal and two numerical beams. It is demonstrated that the proposed statistics-based damage index is sensitive to damage and shows some robustness to the noise and false estimation of the system ranks. The method is capable of locating damage of the beam structures under different types of excitations. The robustness of the proposed damage detection method to the variations in environmental temperature is further validated in a companion paper by a reinforced concrete beam tested in the laboratory and a full-scale arch bridge tested in the field.

What Makes the Optimal Wound Healing Material? A Review of Current Science and Introduction of a Synthetic Nanofabricated Wound Care Scaffold.

PubMed

MacEwan, Matthew R; MacEwan, Sarah; Kovacs, Tamas R; Batts, Joel

2017-10-02

Wound matrix materials are used to improve the regeneration of dermal and epidermal layers in both acute and chronic wounds. Contemporary wound matrices are primarily composed of biologic materials such as processed xenogeneic and allogeneic tissues. Unfortunately, existing biologic wound matrices possess multiple limitations including poor longevity, durability, strength, and enzymatic resistance required for persistent support for new tissue formation. A fully-synthetic, resorbable electrospun material (Restrata Wound Matrix, Acera, St.Louis, Missouri ) that exhibits structural similarities to the native extracellular matrix offers a new approach to the treatment of acute and chronic wounds. This novel matrix is the first product to combine the advantages of synthetic construction (e.g. resistance to enzymatic degradation, excellent biocompatibility, strength/durability and controlled degradation) with the positive attributes of biologic materials (e.g. biomimetic architecture similar to human extracellular matrix (ECM), fibrous architecture optimized to support cellular migration and proliferation, engineered porosity to encourage tissue ingrowth and vascularization). These features allow RWM to achieve rapid and complete healing of full-thickness wounds that, in preclinical studies, is comparable to Integra Bilayer Wound Matrix (Integra LifeSciences, Plainsboro, New Jersey), a gold standard biologic material with diverse clinical indications in the wound care. Together, this review suggests that the RWM offers a unique fully-synthetic alternative to existing biologic matrices that is effective, widely available, easy to store, simple to apply and low cost.

Hi-Corrector: a fast, scalable and memory-efficient package for normalizing large-scale Hi-C data.

PubMed

Li, Wenyuan; Gong, Ke; Li, Qingjiao; Alber, Frank; Zhou, Xianghong Jasmine

2015-03-15

Genome-wide proximity ligation assays, e.g. Hi-C and its variant TCC, have recently become important tools to study spatial genome organization. Removing biases from chromatin contact matrices generated by such techniques is a critical preprocessing step of subsequent analyses. The continuing decline of sequencing costs has led to an ever-improving resolution of the Hi-C data, resulting in very large matrices of chromatin contacts. Such large-size matrices, however, pose a great challenge on the memory usage and speed of its normalization. Therefore, there is an urgent need for fast and memory-efficient methods for normalization of Hi-C data. We developed Hi-Corrector, an easy-to-use, open source implementation of the Hi-C data normalization algorithm. Its salient features are (i) scalability-the software is capable of normalizing Hi-C data of any size in reasonable times; (ii) memory efficiency-the sequential version can run on any single computer with very limited memory, no matter how little; (iii) fast speed-the parallel version can run very fast on multiple computing nodes with limited local memory. The sequential version is implemented in ANSI C and can be easily compiled on any system; the parallel version is implemented in ANSI C with the MPI library (a standardized and portable parallel environment designed for solving large-scale scientific problems). The package is freely available at http://zhoulab.usc.edu/Hi-Corrector/. © The Author 2014. Published by Oxford University Press.

Nanomaterials in consumer products: a challenging analytical problem

PubMed Central

Contado, Catia

2015-01-01

Many products used in everyday life are made with the assistance of nanotechnologies. Cosmetic, pharmaceuticals, sunscreen, powdered food are only few examples of end products containing nano-sized particles (NPs), generally added to improve the product quality. To evaluate correctly benefits vs. risks of engineered nanomaterials and consequently to legislate in favor of consumer's protection, it is necessary to know the hazards connected with the exposure levels. This information implies transversal studies and a number of different competences. On analytical point of view the identification, quantification and characterization of NPs in food matrices and in cosmetic or personal care products pose significant challenges, because NPs are usually present at low concentration levels and the matrices, in which they are dispersed, are complexes and often incompatible with analytical instruments that would be required for their detection and characterization. This paper focused on some analytical techniques suitable for the detection, characterization and quantification of NPs in food and cosmetics products, reports their recent application in characterizing specific metal and metal-oxide NPs in these two important industrial and market sectors. The need of a characterization of the NPs as much as possible complete, matching complementary information about different metrics, possible achieved through validate procedures, is what clearly emerges from this research. More work should be done to produce standardized materials and to set-up methodologies to determine number-based size distributions and to get quantitative date about the NPs in such a complex matrices. PMID:26301216

Development of a bar adsorptive micro-extraction-large-volume injection-gas chromatography-mass spectrometric method for pharmaceuticals and personal care products in environmental water matrices.

PubMed

Neng, N R; Nogueira, J M F

2012-01-01

The combination of bar adsorptive micro-extraction using activated carbon (AC) and polystyrene-divinylbenzene copolymer (PS-DVB) sorbent phases, followed by liquid desorption and large-volume injection gas chromatography coupled to mass spectrometry, under selected ion monitoring mode acquisition, was developed for the first time to monitor pharmaceutical and personal care products (PPCPs) in environmental water matrices. Assays performed on 25 mL water samples spiked (100 ng L(-1)) with caffeine, gemfibrozil, triclosan, propranolol, carbamazepine and diazepam, selected as model compounds, yielded recoveries ranging from 74% to 99% under optimised experimental conditions (equilibrium time, 16 h (1,000 rpm); matrix characteristics: pH 5, 5% NaCl for AC phase; LD: methanol/acetonitrile (1:1), 45 min). The analytical performance showed good precision (RSD < 18%), convenient detection limits (5-20 ng L(-1)) and excellent linear dynamic range (20-800 ng L(-1)) with remarkable determination coefficients (r(2) > 0.99), where the PS-DVB sorbent phase showed a much better efficiency. By using the standard addition methodology, the application of the present analytical approach on tap, ground, sea, estuary and wastewater samples allowed very good performance at the trace level. The proposed method proved to be a suitable sorption-based micro-extraction alternative for the analysis of priority pollutants with medium-polar to polar characteristics, showing to be easy to implement, reliable, sensitive and requiring a low sample volume to monitor PPCPs in water matrices.

Enhancement for trace analysis of sulfonamide antibiotics in water matrices using bar adsorptive microextraction (BAμE).

PubMed

Ide, A H; Ahmad, S M; Neng, N R; Nogueira, J M F

2016-09-10

In this study, the enhancement for trace analysis of sulfonamide antibiotics (sulfathiazole, sulfamethoxazole and sulfadimethoxine) and trimethoprim in water matrices is proposed using bar adsorptive microextraction combined with micro-liquid desorption followed by high-performance liquid chromatography with diode array detection (BAμE-μLD/HPLC-DAD). By comparing different polymers and activated carbons as sorbent coatings for BAμE, the polystyrene-divinylbenzene polymer (PS-DVB) showed the best selectivity for the compounds under study. Assays performed through BAμE(PS-DVB)-μLD on 25mL of ultrapure water samples spiked at the 8.0μgL(-1) level showed recoveries ranging from 63.8±1.5% to 84.2±1.9%, under optimized experimental conditions. The validated method provided satisfactory limits of detection (0.08-0.16μgL(-1)) and good linear dynamic ranges (0.16-8.00μgL(-1)) with determination coefficients higher than 0.9958. The proposed analytical methodology was applied to real matrices, such as tap, estuarine and wastewater samples using the standard addition method. It showed to be easy to implement, with good reproducibility, sensitivity and requiring small amount of sample. Furthermore, negligible consumption of organic solvents was used in compliance with the green analytical chemistry principles. When compared to other well-established microextraction approaches, BAμE demonstrated better performance concerning recovery yields and sensitivity. Copyright © 2016 Elsevier B.V. All rights reserved.

Working Around Cosmic Variance: Remote Quadrupole Measurements of the CMB

NASA Astrophysics Data System (ADS)

Adil, Arsalan; Bunn, Emory

2018-01-01

Anisotropies in the CMB maps continue to revolutionize our understanding of the Cosmos. However, the statistical interpretation of these anisotropies is tainted with a posteriori statistics. The problem is particularly emphasized for lower order multipoles, i.e. in the cosmic variance regime of the power spectrum. Naturally, the solution lies in acquiring a new data set – a rather difficult task given the sample size of the Universe.The CMB temperature, in theory, depends on: the direction of photon propagation, the time at which the photons are observed, and the observer’s location in space. In existing CMB data, only the first parameter varies. However, as first pointed out by Kamionkowski and Loeb, a solution lies in making the so-called “Remote Quadrupole Measurements” by analyzing the secondary polarization produced by incoming CMB photons via the Sunyaev-Zel’dovich (SZ) effect. These observations allow us to measure the projected CMB quadrupole at the location and look-back time of a galaxy cluster.At low redshifts, the remote quadrupole is strongly correlated to the CMB anisotropy from our last scattering surface. We provide here a formalism for computing the covariance and relation matrices for both the two-point correlation function on the last scattering surface of a galaxy cluster and the cross correlation of the remote quadrupole with the local CMB. We then calculate these matrices based on a fiducial model and a non-standard model that suppresses power at large angles for ~104 clusters up to z=2. We anticipate to make a priori predictions of the differences between our expectations for the standard and non-standard models. Such an analysis is timely in the wake of the CMB S4 era which will provide us with an extensive SZ cluster catalogue.

The underexposed role of food matrices in probiotic products: Reviewing the relationship between carrier matrices and product parameters.

PubMed

Flach, Joost; van der Waal, Mark B; van den Nieuwboer, Maurits; Claassen, Eric; Larsen, Olaf F A

2017-06-13

Probiotic microorganisms are increasingly incorporated into food matrices in order to confer proposed health benefits on the consumer. It is important that the health benefits, sensory properties, shelf-life and probiotic gastrointestinal tract (GIT) survival of these products are carefully balanced as they determine functionality and drive consumer acceptance. The strain-specific effects of probiotic species are imperative in this process but carrier matrices may play a pivotal role as well. This study therefore recapitulates the wealth of knowledge on carrier matrices and their interaction with probiotic strains. The most substantiated carrier matrices, factors that influence probiotic functionality and matrix effects on shelf-life, GIT survival and clinical efficacy are reviewed. Results indicate that carrier matrices have a significant impact on the quality of probiotic products. Matrix components, such as proteins, carbohydrates and flavoring agents are shown to alter probiotic efficacy and viability. In vivo studies furthermore revealed strain-dependent matrix effects on the GIT survival of probiotic bacteria. However, only a limited number of studies have specifically addressed the effects of carrier matrices on the aforementioned product-parameters; most studies seem to focus solely on the strain-specific effects of probiotic microorganisms. This hampers the innovation of probiotic products. More human studies, comparing not only different probiotic strains but different carrier matrices as well, are needed to drive the innovation cycle.

Electrospun Zein/PCL Fibrous Matrices Release Tetracycline in a Controlled Manner, Killing Staphylococcus aureus Both in Biofilms and Ex Vivo on Pig Skin, and are Compatible with Human Skin Cells.

PubMed

Alhusein, Nour; Blagbrough, Ian S; Beeton, Michael L; Bolhuis, Albert; De Bank, Paul A

2016-01-01

To investigate the destruction of clinically-relevant bacteria within biofilms via the sustained release of the antibiotic tetracycline from zein-based electrospun polymeric fibrous matrices and to demonstrate the compatibility of such wound dressing matrices with human skin cells. Zein/PCL triple layered fibrous dressings with entrapped tetracycline were electrospun. The successful entrapment of tetracycline in these dressings was validated. The successful release of bioactive tetracycline, the destruction of preformed biofilms, and the viability of fibroblast (FEK4) cells were investigated. The sustained release of tetracycline from these matrices led to the efficient destruction of preformed biofilms from Staphylococcus aureus MRSA252 in vitro, and of MRSA252 and ATCC 25923 bacteria in an ex vivo pig skin model using 1 × 1 cm square matrices containing tetracycline (30 μg). Human FEK4 cells grew normally in the presence of these matrices. The ability of the zein-based matrices to destroy bacteria within increasingly complex in vitro biofilm models was clearly established. An ex vivo pig skin assay showed that these matrices, with entrapped tetracycline, efficiently kill bacteria and this, combined with their compatibility with a human skin cell line suggest these matrices are well suited for applications in wound healing and infection control.

Core-shell alginate-ghatti gum modified montmorillonite composite matrices for stomach-specific flurbiprofen delivery.

PubMed

Bera, Hriday; Ippagunta, Sohitha Reddy; Kumar, Sanoj; Vangala, Pavani

2017-07-01

Novel alginate-arabic gum (AG) gel membrane coated alginate-ghatti gum (GG) modified montmorillonite (MMT) composite matrices were developed for intragastric flurbiprofen (FLU) delivery by combining floating and mucoadhesion mechanisms. The clay-biopolymer composite matrices containing FLU as core were accomplished by ionic-gelation technique. Effects of polymer-blend (alginate:GG) ratios and crosslinker (CaCl 2 ) concentrations on drug entrapment efficiency (DEE, %) and cumulative drug release after 8h (Q 8h , %) were studied to optimize the core matrices by a 3 2 factorial design. The optimized matrices (F-O) demonstrated DEE of 91.69±1.43% and Q 8h of 74.96±1.56% with minimum errors in prediction. The alginate-AG gel membrane enveloped optimized matrices (F-O, coated) exhibited superior buoyancy, better ex vivo mucoadhesion and slower drug release rate. The drug release profile of FLU-loaded uncoated and coated optimized matrices was best fitted in Korsmeyer-Peppas model with anomalous diffusion and case-II transport driven mechanism, respectively. The uncoated and coated matrices containing FLU were also characterized for drug-excipients compatibility, drug crystallinity, thermal behaviour and surface morphology. Thus, the newly developed alginate-AG gel membrane coated alginate-GG modified MMT composite matrices are appropriate for intragastric delivery of FLU over an extended period of time with improved therapeutic benefits. Copyright © 2017 Elsevier B.V. All rights reserved.

"Progress or Abuse--A Choice." A Study to Investigate the Need for Legislative and Administrative Actions Regarding Standards of Progress Provisions of the GI Bill and Class Session Requirements of the Veterans' Administration Regulations.

ERIC Educational Resources Information Center

Veterans Administration, Washington, DC.

The need for legislative and administrative action was examined in regard to the GI Bill and the satisfactory progress requirements and the "seat-time" requirements prescribed by regulation. Information is presented on the GI Bill Improvement Act of 1977 (P.L. 95-202), standards of progress of the veteran student, and contact time, or…

Novel value-added uses for sweet potato juice and flour in polyphenol- and protein-enriched functional food ingredients.

PubMed

Grace, Mary H; Truong, An N; Truong, Van-Den; Raskin, Ilya; Lila, Mary Ann

2015-09-01

Blackcurrant, blueberry, and muscadine grape juices were efficiently sorbed, concentrated, and stabilized into dry granular ingredient matrices which combined anti-inflammatory and antioxidant fruit polyphenols with sweet potato functional constituents (carotenoids, vitamins, polyphenols, fibers). Total phenolics were highest in blackcurrant-orange sweet potato ingredient matrices (34.03 mg/g), and lowest in muscadine grape-yellow sweet potato matrices (10.56 mg/g). Similarly, anthocyanins were most concentrated in blackcurrant-fortified orange and yellow sweet potato matrices (5.40 and 6.54 mg/g, respectively). Alternatively, other protein-rich edible matrices (defatted soy flour, light roasted peanut flour, and rice protein concentrate) efficiently captured polyphenols (6.09-9.46 mg/g) and anthocyanins (0.77-1.27 mg/g) from purple-fleshed sweet potato juice, with comparable efficiency. Antioxidant activity correlated well with total phenolic content. All formulated ingredient matrices stabilized and preserved polyphenols for up to 24 weeks, even when stored at 37°C. Complexation with juice-derived polyphenols did not significantly alter protein or carbohydrate profiles of the matrices. Sensory evaluation of the ingredient matrices suggested potential uses for a wide range of functional food products.

Surface-enhanced Raman spectroscopy introduced into the International Standard Organization (ISO) regulations as an alternative method for detection and identification of pathogens in the food industry.

PubMed

Witkowska, Evelin; Korsak, Dorota; Kowalska, Aneta; Księżopolska-Gocalska, Monika; Niedziółka-Jönsson, Joanna; Roźniecka, Ewa; Michałowicz, Weronika; Albrycht, Paweł; Podrażka, Marta; Hołyst, Robert; Waluk, Jacek; Kamińska, Agnieszka

2017-02-01

We show that surface-enhanced Raman spectroscopy (SERS) coupled with principal component analysis (PCA) can serve as a fast, reliable, and easy method for detection and identification of food-borne bacteria, namely Salmonella spp., Listeria monocytogenes, and Cronobacter spp., in different types of food matrices (salmon, eggs, powdered infant formula milk, mixed herbs, respectively). The main aim of this work was to introduce the SERS technique into three ISO (6579:2002; 11290-1:1996/A1:2004; 22964:2006) standard procedures required for detection of these bacteria in food. Our study demonstrates that the SERS technique is effective in distinguishing very closely related bacteria within a genus grown on solid and liquid media. The advantages of the proposed ISO-SERS method for bacteria identification include simplicity and reduced time of analysis, from almost 144 h required by standard methods to 48 h for the SERS-based approach. Additionally, PCA allows one to perform statistical classification of studied bacteria and to identify the spectrum of an unknown sample. Calculated first and second principal components (PC-1, PC-2) account for 96, 98, and 90% of total variance in the spectra and enable one to identify the Salmonella spp., L. monocytogenes, and Cronobacter spp., respectively. Moreover, the presented study demonstrates the excellent possibility for simultaneous detection of analyzed food-borne bacteria in one sample test (98% of PC-1 and PC-2) with a goal of splitting the data set into three separated clusters corresponding to the three studied bacteria species. The studies described in this paper suggest that SERS represents an alternative to standard microorganism diagnostic procedures. Graphical Abstract New approach of the SERS strategy for detection and identification of food-borne bacteria, namely S. enterica, L. monocytogenes, and C. sakazakii in selected food matrices.

Inference for High-dimensional Differential Correlation Matrices.

PubMed

Cai, T Tony; Zhang, Anru

2016-01-01

Motivated by differential co-expression analysis in genomics, we consider in this paper estimation and testing of high-dimensional differential correlation matrices. An adaptive thresholding procedure is introduced and theoretical guarantees are given. Minimax rate of convergence is established and the proposed estimator is shown to be adaptively rate-optimal over collections of paired correlation matrices with approximately sparse differences. Simulation results show that the procedure significantly outperforms two other natural methods that are based on separate estimation of the individual correlation matrices. The procedure is also illustrated through an analysis of a breast cancer dataset, which provides evidence at the gene co-expression level that several genes, of which a subset has been previously verified, are associated with the breast cancer. Hypothesis testing on the differential correlation matrices is also considered. A test, which is particularly well suited for testing against sparse alternatives, is introduced. In addition, other related problems, including estimation of a single sparse correlation matrix, estimation of the differential covariance matrices, and estimation of the differential cross-correlation matrices, are also discussed.

On Fluctuations of Eigenvalues of Random Band Matrices

NASA Astrophysics Data System (ADS)

Shcherbina, M.

2015-10-01

We consider the fluctuations of linear eigenvalue statistics of random band matrices whose entries have the form with i.i.d. possessing the th moment, where the function u has a finite support , so that M has only nonzero diagonals. The parameter b (called the bandwidth) is assumed to grow with n in a way such that . Without any additional assumptions on the growth of b we prove CLT for linear eigenvalue statistics for a rather wide class of test functions. Thus we improve and generalize the results of the previous papers (Jana et al., arXiv:1412.2445; Li et al. Random Matrices 2:04, 2013), where CLT was proven under the assumption . Moreover, we develop a method which allows to prove automatically the CLT for linear eigenvalue statistics of the smooth test functions for almost all classical models of random matrix theory: deformed Wigner and sample covariance matrices, sparse matrices, diluted random matrices, matrices with heavy tales etc.

ESI and MALDI Mass Spectrometry of Large POSS Oligomers (Preprint)

DTIC Science & Technology

2010-03-10

Bryan Coughlin¦, Gunjan Gadodia¦, David F . Marten†, Julie Ray†, and Michael T. Bowers⊥* Department of Chemistry & Biochemistry, University of...difficult or even impossible to investigate using standard matrices. ) actable o rt HO F F F F N OH FF FF N Figure 1. 4,4...n =4 n = 5 n = 6 % f 16 each sub-series(e.g. m/z ~7960, series d) grows in relative intensity and is best interpreted as the loss of a second

An Approximate Approach to Automatic Kernel Selection.

PubMed

Ding, Lizhong; Liao, Shizhong

2016-02-02

Kernel selection is a fundamental problem of kernel-based learning algorithms. In this paper, we propose an approximate approach to automatic kernel selection for regression from the perspective of kernel matrix approximation. We first introduce multilevel circulant matrices into automatic kernel selection, and develop two approximate kernel selection algorithms by exploiting the computational virtues of multilevel circulant matrices. The complexity of the proposed algorithms is quasi-linear in the number of data points. Then, we prove an approximation error bound to measure the effect of the approximation in kernel matrices by multilevel circulant matrices on the hypothesis and further show that the approximate hypothesis produced with multilevel circulant matrices converges to the accurate hypothesis produced with kernel matrices. Experimental evaluations on benchmark datasets demonstrate the effectiveness of approximate kernel selection.

Homology search with binary and trinary scoring matrices.

PubMed

Smith, Scott F

2006-01-01

Protein homology search can be accelerated with the use of bit-parallel algorithms in conjunction with constraints on the values contained in the scoring matrices. Trinary scoring matrices (containing only the values -1, 0, and 1) allow for significant acceleration without significant reduction in the receiver operating characteristic (ROC) score of a Smith-Waterman search. Binary scoring matrices (containing the values 0 and 1) result in some reduction in ROC score, but result in even more acceleration. Binary scoring matrices and five-bit saturating scores can be used for fast prefilters to the Smith-Waterman algorithm.

Methods for Quantum Circuit Design and Simulation

DTIC Science & Technology

2010-03-01

cannot be deter- mined given the one output. Reversible gates, expressed mathematically, are unitary matrices. 16 3.3.1 PAULI Gates/Matrices Three...common single-qubit gates are expressed mathematically as Pauli matrices, which are 2x2 matrices. A 2x2 quantum gate can be applied to a single quantum...bit (a 2x1 column vector). The Pauli matrices are expressed as follows: X =   0 1 1 0   Y =   0 −i i 0   Z =   1 0 0 −1   (3.10) where i

An automated procedure for calculating system matrices from perturbation data generated by an EAI Pacer and 100 hybrid computer system

NASA Technical Reports Server (NTRS)

Milner, E. J.; Krosel, S. M.

1977-01-01

Techniques are presented for determining the elements of the A, B, C, and D state variable matrices for systems simulated on an EAI Pacer 100 hybrid computer. An automated procedure systematically generates disturbance data necessary to linearize the simulation model and stores these data on a floppy disk. A separate digital program verifies this data, calculates the elements of the system matrices, and prints these matrices appropriately labeled. The partial derivatives forming the elements of the state variable matrices are approximated by finite difference calculations.

Nonlinear optical microscopy reveals invading endothelial cells anisotropically alter three-dimensional collagen matrices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, P.-F.; Yeh, Alvin T.; Bayless, Kayla J.

The interactions between endothelial cells (ECs) and the extracellular matrix (ECM) are fundamental in mediating various steps of angiogenesis, including cell adhesion, migration and sprout formation. Here, we used a noninvasive and non-destructive nonlinear optical microscopy (NLOM) technique to optically image endothelial sprouting morphogenesis in three-dimensional (3D) collagen matrices. We simultaneously captured signals from collagen fibers and endothelial cells using second harmonic generation (SHG) and two-photon excited fluorescence (TPF), respectively. Dynamic 3D imaging revealed EC interactions with collagen fibers along with quantifiable alterations in collagen matrix density elicited by EC movement through and morphogenesis within the matrix. Specifically, we observedmore » increased collagen density in the area between bifurcation points of sprouting structures and anisotropic increases in collagen density around the perimeter of lumenal structures, but not advancing sprout tips. Proteinase inhibition studies revealed membrane-associated matrix metalloproteinase were utilized for sprout advancement and lumen expansion. Rho-associated kinase (p160ROCK) inhibition demonstrated that the generation of cell tension increased collagen matrix alterations. This study followed sprouting ECs within a 3D matrix and revealed that the advancing structures recognize and significantly alter their extracellular environment at the periphery of lumens as they progress.« less

Effect of high-dose vs standard-dose multivitamin supplementation at the initiation of HAART on HIV disease progression and mortality in Tanzania: a randomized controlled trial.

PubMed

Isanaka, Sheila; Mugusi, Ferdinand; Hawkins, Claudia; Spiegelman, Donna; Okuma, James; Aboud, Said; Guerino, Chalamilla; Fawzi, Wafaie W

2012-10-17

Large randomized trials have previously shown that high-dose micronutrient supplementation can increase CD4 counts and reduce human immunodeficiency virus (HIV) disease progression and mortality among individuals not receiving highly active antiretroviral therapy (HAART); however, the safety and efficacy of such supplementation has not been established in the context of HAART. To test the hypothesis that high-dose multivitamin supplementation vs standard-dose multivitamin supplementation decreases the risk of HIV disease progression or death and improves immunological, virological, and nutritional parameters in patients with HIV initiating HAART. A randomized, double-blind, controlled trial of high-dose vs standard-dose multivitamin supplementation for 24 months in 3418 patients with HIV initiating HAART between November 2006 and November 2008 in 7 clinics in Dar es Salaam, Tanzania. INTERVENTION The provision of daily oral supplements of vitamin B complex, vitamin C, and vitamin E at high levels or standard levels of the recommended dietary allowance. The composite of HIV disease progression or death from any cause. The study was stopped early in March 2009 because of evidence of increased levels of alanine transaminase (ALT) in patients receiving the high-dose multivitamin supplement. At the time of stopping, 3418 patients were enrolled (median follow-up, 15 months), and there were 2374 HIV disease progression events and 453 observed deaths (2460 total combined events). Compared with standard-dose multivitamin supplementation, high-dose supplementation did not reduce the risk of HIV disease progression or death. The absolute risk of HIV progression or death was 72% in the high-dose group vs 72% in the standard-dose group (risk ratio [RR], 1.00; 95% CI, 0.96-1.04). High-dose supplementation had no effect on CD4 count, plasma viral load, body mass index, or hemoglobin level concentration, but increased the risk of ALT elevations (1239 events per 1215 person-years vs 879 events per 1236 person-years; RR, 1.44; 95% CI, 1.11-1.87) vs standard-dose supplementation. CONCLUSION In adults receiving HAART, use of high-dose multivitamin supplements compared with standard-dose multivitamin supplements did not result in a decrease in HIV disease progression or death but may have resulted in an increase in ALT levels. Clinicaltrials.gov Identifier: NCT00383669.

Invertible flexible matrices

NASA Astrophysics Data System (ADS)

Justino, Júlia

2017-06-01

Matrices with coefficients having uncertainties of type o (.) or O (.), called flexible matrices, are studied from the point of view of nonstandard analysis. The uncertainties of the afore-mentioned kind will be given in the form of the so-called neutrices, for instance the set of all infinitesimals. Since flexible matrices have uncertainties in their coefficients, it is not possible to define the identity matrix in an unique way and so the notion of spectral identity matrix arises. Not all nonsingular flexible matrices can be turned into a spectral identity matrix using Gauss-Jordan elimination method, implying that that not all nonsingular flexible matrices have the inverse matrix. Under certain conditions upon the size of the uncertainties appearing in a nonsingular flexible matrix, a general theorem concerning the boundaries of its minors is presented which guarantees the existence of the inverse matrix of a nonsingular flexible matrix.

Statistical potential-based amino acid similarity matrices for aligning distantly related protein sequences.

PubMed

Tan, Yen Hock; Huang, He; Kihara, Daisuke

2006-08-15

Aligning distantly related protein sequences is a long-standing problem in bioinformatics, and a key for successful protein structure prediction. Its importance is increasing recently in the context of structural genomics projects because more and more experimentally solved structures are available as templates for protein structure modeling. Toward this end, recent structure prediction methods employ profile-profile alignments, and various ways of aligning two profiles have been developed. More fundamentally, a better amino acid similarity matrix can improve a profile itself; thereby resulting in more accurate profile-profile alignments. Here we have developed novel amino acid similarity matrices from knowledge-based amino acid contact potentials. Contact potentials are used because the contact propensity to the other amino acids would be one of the most conserved features of each position of a protein structure. The derived amino acid similarity matrices are tested on benchmark alignments at three different levels, namely, the family, the superfamily, and the fold level. Compared to BLOSUM45 and the other existing matrices, the contact potential-based matrices perform comparably in the family level alignments, but clearly outperform in the fold level alignments. The contact potential-based matrices perform even better when suboptimal alignments are considered. Comparing the matrices themselves with each other revealed that the contact potential-based matrices are very different from BLOSUM45 and the other matrices, indicating that they are located in a different basin in the amino acid similarity matrix space.

The Development of Novel Nanodiamond Based MALDI Matrices for the Analysis of Small Organic Pharmaceuticals

NASA Astrophysics Data System (ADS)

Chitanda, Jackson M.; Zhang, Haixia; Pahl, Erica; Purves, Randy W.; El-Aneed, Anas

2016-10-01

The utility of novel functionalized nanodiamonds (NDs) as matrices for matrix-assisted laser desorption ionization-mass spectrometry (MALDI-MS) is described herein. MALDI-MS analysis of small organic compounds (<1000 Da) is typically complex because of interferences from numerous cluster ions formed when using conventional matrices. To expand the use of MALDI for the analysis of small molecules, novel matrices were designed by covalently linking conventional matrices (or a lysine moiety) to detonated NDs. Four new functionalized NDs were evaluated for their ionization capabilities using five pharmaceuticals with varying molecular structures. Two ND matrices were able to ionize all tested pharmaceuticals in the negative ion mode, producing the deprotonated ions [M - H]-. Ion intensity for target analytes was generally strong with enhanced signal-to-noise ratios compared with conventional matrices. The negative ion mode is of great importance for biological samples as interference from endogenous compounds is inherently minimized in the negative ion mode. Since the molecular structures of the tested pharmaceuticals did not suggest that negative ion mode would be preferable, this result magnifies the importance of these findings. On the other hand, conventional matrices primarily facilitated the ionization as expected in the positive ion mode, producing either the protonated molecules [M + H]+ or cationic adducts (typically producing complex spectra with numerous adduct peaks). The data presented in this study suggests that these matrices may offer advantages for the analysis of low molecular weight pharmaceuticals/metabolites.

The Development of Novel Nanodiamond Based MALDI Matrices for the Analysis of Small Organic Pharmaceuticals.

PubMed

Chitanda, Jackson M; Zhang, Haixia; Pahl, Erica; Purves, Randy W; El-Aneed, Anas

2016-10-01

The utility of novel functionalized nanodiamonds (NDs) as matrices for matrix-assisted laser desorption ionization-mass spectrometry (MALDI-MS) is described herein. MALDI-MS analysis of small organic compounds (<1000 Da) is typically complex because of interferences from numerous cluster ions formed when using conventional matrices. To expand the use of MALDI for the analysis of small molecules, novel matrices were designed by covalently linking conventional matrices (or a lysine moiety) to detonated NDs. Four new functionalized NDs were evaluated for their ionization capabilities using five pharmaceuticals with varying molecular structures. Two ND matrices were able to ionize all tested pharmaceuticals in the negative ion mode, producing the deprotonated ions [M - H](-). Ion intensity for target analytes was generally strong with enhanced signal-to-noise ratios compared with conventional matrices. The negative ion mode is of great importance for biological samples as interference from endogenous compounds is inherently minimized in the negative ion mode. Since the molecular structures of the tested pharmaceuticals did not suggest that negative ion mode would be preferable, this result magnifies the importance of these findings. On the other hand, conventional matrices primarily facilitated the ionization as expected in the positive ion mode, producing either the protonated molecules [M + H](+) or cationic adducts (typically producing complex spectra with numerous adduct peaks). The data presented in this study suggests that these matrices may offer advantages for the analysis of low molecular weight pharmaceuticals/metabolites. Graphical Abstract ᅟ.

Progress on a generalized coordinates tensor product finite element 3DPNS algorithm for subsonic

NASA Technical Reports Server (NTRS)

Baker, A. J.; Orzechowski, J. A.

1983-01-01

A generalized coordinates form of the penalty finite element algorithm for the 3-dimensional parabolic Navier-Stokes equations for turbulent subsonic flows was derived. This algorithm formulation requires only three distinct hypermatrices and is applicable using any boundary fitted coordinate transformation procedure. The tensor matrix product approximation to the Jacobian of the Newton linear algebra matrix statement was also derived. Tne Newton algorithm was restructured to replace large sparse matrix solution procedures with grid sweeping using alpha-block tridiagonal matrices, where alpha equals the number of dependent variables. Numerical experiments were conducted and the resultant data gives guidance on potentially preferred tensor product constructions for the penalty finite element 3DPNS algorithm.

Characterization of good teleoperators - What aptitudes, interests, and experience correlate with measures of teleoperator performance

NASA Technical Reports Server (NTRS)

Yorchak, J. P.; Hartley, C. S.; Hinman, E.

1985-01-01

The use of aptitude tests and questionnaries to evaluate an individuals aptitude for teleoperation is studied. The Raven Progressive Matrices Test and Differential Aptitude Tests, and a 16-item questionnaire for assessing the subject's interests, academic background, and previous experience are described. The Proto-Flight Manipulator Arm, cameras, console, hand controller, and task board utilized by the 17 engineers are examined. The correlation between aptitude scores and questionnaire responses, and operator performance is investigated. Multiple regression data reveal that the eight predictor variables are not individually significant for evaluating operator performance; however, the complete test battery is applicable for predicting 49 percent of subject variance on the criterion task.

A neural model of rule generation in inductive reasoning.

PubMed

Rasmussen, Daniel; Eliasmith, Chris

2011-01-01

Inductive reasoning is a fundamental and complex aspect of human intelligence. In particular, how do subjects, given a set of particular examples, generate general descriptions of the rules governing that set? We present a biologically plausible method for accomplishing this task and implement it in a spiking neuron model. We demonstrate the success of this model by applying it to the problem domain of Raven's Progressive Matrices, a widely used tool in the field of intelligence testing. The model is able to generate the rules necessary to correctly solve Raven's items, as well as recreate many of the experimental effects observed in human subjects. Copyright © 2011 Cognitive Science Society, Inc.

Extraction and Analysis of Sulfur Mustard (HD) from Various Food Matrices by Gas ChromatographyMass Spectrometry

DTIC Science & Technology

2016-01-01

EXTRACTION AND ANALYSIS OF SULFUR MUSTARD (HD) FROM VARIOUS FOOD MATRICES BY GAS CHROMATOGRAPHY–MASS...Sulfur Mustard (HD) from Various Food Matrices by Gas Chromatography–Mass Spectrometry 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT...spectrometry was used to analyze sulfur mustard (HD) in various food matrices. The development of a solid-phase extraction method using a normal

Novel value-added uses for sweet potato juice and flour in polyphenol- and protein-enriched functional food ingredients

PubMed Central

Grace, Mary H; Truong, An N; Truong, Van-Den; Raskin, Ilya; Lila, Mary Ann

2015-01-01

Blackcurrant, blueberry, and muscadine grape juices were efficiently sorbed, concentrated, and stabilized into dry granular ingredient matrices which combined anti-inflammatory and antioxidant fruit polyphenols with sweet potato functional constituents (carotenoids, vitamins, polyphenols, fibers). Total phenolics were highest in blackcurrant-orange sweet potato ingredient matrices (34.03 mg/g), and lowest in muscadine grape-yellow sweet potato matrices (10.56 mg/g). Similarly, anthocyanins were most concentrated in blackcurrant-fortified orange and yellow sweet potato matrices (5.40 and 6.54 mg/g, respectively). Alternatively, other protein-rich edible matrices (defatted soy flour, light roasted peanut flour, and rice protein concentrate) efficiently captured polyphenols (6.09–9.46 mg/g) and anthocyanins (0.77–1.27 mg/g) from purple-fleshed sweet potato juice, with comparable efficiency. Antioxidant activity correlated well with total phenolic content. All formulated ingredient matrices stabilized and preserved polyphenols for up to 24 weeks, even when stored at 37°C. Complexation with juice-derived polyphenols did not significantly alter protein or carbohydrate profiles of the matrices. Sensory evaluation of the ingredient matrices suggested potential uses for a wide range of functional food products. PMID:26405527

The performance of the Congruence Among Distance Matrices (CADM) test in phylogenetic analysis

PubMed Central

2011-01-01

Background CADM is a statistical test used to estimate the level of Congruence Among Distance Matrices. It has been shown in previous studies to have a correct rate of type I error and good power when applied to dissimilarity matrices and to ultrametric distance matrices. Contrary to most other tests of incongruence used in phylogenetic analysis, the null hypothesis of the CADM test assumes complete incongruence of the phylogenetic trees instead of congruence. In this study, we performed computer simulations to assess the type I error rate and power of the test. It was applied to additive distance matrices representing phylogenies and to genetic distance matrices obtained from nucleotide sequences of different lengths that were simulated on randomly generated trees of varying sizes, and under different evolutionary conditions. Results Our results showed that the test has an accurate type I error rate and good power. As expected, power increased with the number of objects (i.e., taxa), the number of partially or completely congruent matrices and the level of congruence among distance matrices. Conclusions Based on our results, we suggest that CADM is an excellent candidate to test for congruence and, when present, to estimate its level in phylogenomic studies where numerous genes are analysed simultaneously. PMID:21388552

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory; determination of antimony by automated-hydride atomic absorption spectrophotometry

USGS Publications Warehouse

Brown, G.E.; McLain, B.J.

1994-01-01

The analysis of natural-water samples for antimony by automated-hydride atomic absorption spectrophotometry is described. Samples are prepared for analysis by addition of potassium and hydrochloric acid followed by an autoclave digestion. After the digestion, potassium iodide and sodium borohydride are added automatically. Antimony hydride (stibine) gas is generated, then swept into a heated quartz cell for determination of antimony by atomic absorption spectrophotometry. Precision and accuracy data are presented. Results obtained on standard reference water samples agree with means established by interlaboratory studies. Spike recoveries for actual samples range from 90 to 114 percent. Replicate analyses of water samples of varying matrices give relative standard deviations from 3 to 10 percent.

Comparison of calibration and standardization approaches for fluorescence guided imaging systems to benchtop fluorescence measurements in cellular systems

NASA Astrophysics Data System (ADS)

Litorja, Maritoni; DeRose, Paul

2018-02-01

Fluorescence measurements are a staple in biomedicine, from research and discovery to more recently, for fluorescenceguided imaging systems for diagnostics and surgery. Measurement validation for clinical imagers is a challenge as it is applied to many different optical systems and probe through matrices with different optical properties in a demanding field environment. In this paper we will present approaches to fluorescence calibration for a field system, in comparison to those used in laboratory instruments for cell measurements or benchtop fluorometers. We will present the common challenges and differences, and lessons from the standardization effort of laboratory fluorescence measurements. We will discuss the conceptually different pathways to measurement traceability, between counting moles of substance and measuring light.

Quantitative aspects of inductively coupled plasma mass spectrometry

PubMed Central

Wagner, Barbara

2016-01-01

Accurate determination of elements in various kinds of samples is essential for many areas, including environmental science, medicine, as well as industry. Inductively coupled plasma mass spectrometry (ICP-MS) is a powerful tool enabling multi-elemental analysis of numerous matrices with high sensitivity and good precision. Various calibration approaches can be used to perform accurate quantitative measurements by ICP-MS. They include the use of pure standards, matrix-matched standards, or relevant certified reference materials, assuring traceability of the reported results. This review critically evaluates the advantages and limitations of different calibration approaches, which are used in quantitative analyses by ICP-MS. Examples of such analyses are provided. This article is part of the themed issue ‘Quantitative mass spectrometry’. PMID:27644971

Virial expansion for almost diagonal random matrices

NASA Astrophysics Data System (ADS)

Yevtushenko, Oleg; Kravtsov, Vladimir E.

2003-08-01

Energy level statistics of Hermitian random matrices hat H with Gaussian independent random entries Higeqj is studied for a generic ensemble of almost diagonal random matrices with langle|Hii|2rangle ~ 1 and langle|Hi\

Enantiomer fractions of polychlorinated biphenyls in three selected Standard Reference Materials.

PubMed

Morrissey, Joshua A; Bleackley, Derek S; Warner, Nicholas A; Wong, Charles S

2007-01-01

The enantiomer composition of six chiral polychlorinated biphenyls (PCBs) were measured in three different certified Standard Reference Materials (SRMs) from the US National Institute of Standards and Technology (NIST): SRM 1946 (Lake Superior fish tissue), SRM 1939a (PCB Congeners in Hudson River Sediment), and SRM 2978 (organic contaminants in mussel tissue--Raritan Bay, New Jersey) to aid in quality assurance/quality control methodologies in the study of chiral pollutants in sediments and biota. Enantiomer fractions (EFs) of PCBs 91, 95, 136, 149, 174, and 183 were measured using a suite of chiral columns by gas chromatography/mass spectrometry. Concentrations of target analytes were in agreement with certified values. Target analyte EFs in reference materials were measured precisely (<2% relative standard deviation), indicating the utility of SRM in quality assurance/control methodologies for analyses of chiral compounds in environmental samples. Measured EFs were also in agreement with previously published analyses of similar samples, indicating that similar enantioselective processes were taking place in these environmental matrices.

Inference for High-dimensional Differential Correlation Matrices *

PubMed Central

Cai, T. Tony; Zhang, Anru

2015-01-01

Motivated by differential co-expression analysis in genomics, we consider in this paper estimation and testing of high-dimensional differential correlation matrices. An adaptive thresholding procedure is introduced and theoretical guarantees are given. Minimax rate of convergence is established and the proposed estimator is shown to be adaptively rate-optimal over collections of paired correlation matrices with approximately sparse differences. Simulation results show that the procedure significantly outperforms two other natural methods that are based on separate estimation of the individual correlation matrices. The procedure is also illustrated through an analysis of a breast cancer dataset, which provides evidence at the gene co-expression level that several genes, of which a subset has been previously verified, are associated with the breast cancer. Hypothesis testing on the differential correlation matrices is also considered. A test, which is particularly well suited for testing against sparse alternatives, is introduced. In addition, other related problems, including estimation of a single sparse correlation matrix, estimation of the differential covariance matrices, and estimation of the differential cross-correlation matrices, are also discussed. PMID:26500380

Amino acid "little Big Bang": representing amino acid substitution matrices as dot products of Euclidian vectors.

PubMed

Zimmermann, Karel; Gibrat, Jean-François

2010-01-04

Sequence comparisons make use of a one-letter representation for amino acids, the necessary quantitative information being supplied by the substitution matrices. This paper deals with the problem of finding a representation that provides a comprehensive description of amino acid intrinsic properties consistent with the substitution matrices. We present a Euclidian vector representation of the amino acids, obtained by the singular value decomposition of the substitution matrices. The substitution matrix entries correspond to the dot product of amino acid vectors. We apply this vector encoding to the study of the relative importance of various amino acid physicochemical properties upon the substitution matrices. We also characterize and compare the PAM and BLOSUM series substitution matrices. This vector encoding introduces a Euclidian metric in the amino acid space, consistent with substitution matrices. Such a numerical description of the amino acid is useful when intrinsic properties of amino acids are necessary, for instance, building sequence profiles or finding consensus sequences, using machine learning algorithms such as Support Vector Machine and Neural Networks algorithms.

Role of chromatography in the development of Standard Reference Materials for organic analysis.

PubMed

Wise, Stephen A; Phinney, Karen W; Sander, Lane C; Schantz, Michele M

2012-10-26

The certification of chemical constituents in natural-matrix Standard Reference Materials (SRMs) at the National Institute of Standards and Technology (NIST) can require the use of two or more independent analytical methods. The independence among the methods is generally achieved by taking advantage of differences in extraction, separation, and detection selectivity. This review describes the development of the independent analytical methods approach at NIST, and its implementation in the measurement of organic constituents such as contaminants in environmental materials, nutrients and marker compounds in food and dietary supplement matrices, and health diagnostic and nutritional assessment markers in human serum. The focus of this review is the important and critical role that separation science techniques play in achieving the necessary independence of the analytical steps in the measurement of trace-level organic constituents in natural matrix SRMs. Published by Elsevier B.V.

Standard reference materials (SRMs) for determination of organic contaminants in environmental samples.

PubMed

Wise, Stephen A; Poster, Dianne L; Kucklick, John R; Keller, Jennifer M; Vanderpol, Stacy S; Sander, Lane C; Schantz, Michele M

2006-10-01

For the past 25 years the National Institute of Standards and Technology (NIST) has developed certified reference materials (CRMs), known as standard reference materials (SRMs), for determination of organic contaminants in environmental matrices. Assignment of certified concentrations has usually been based on combining results from two or more independent analytical methods. The first-generation environmental-matrix SRMs were issued with certified concentrations for a limited number (5 to 10) of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). Improvements in the analytical certification approach significantly expanded the number and classes of contaminants determined. Environmental-matrix SRMs currently available include air and diesel particulate matter, coal tar, marine and river sediment, mussel tissue, fish oil and tissue, and human serum, with concentrations typically assigned for 50 to 90 organic contaminants, for example PAHs, nitro-substituted PAHs, PCBs, chlorinated pesticides, and polybrominated diphenyl ethers (PBDEs).

A comparison of the BAX system method to the U.S. Food and Drug Administration's Bacteriological Analytical Manual and International Organization for Standardization reference methods for the detection of Salmonella in a variety of soy ingredients.

PubMed

Belete, Tamrat; Crowley, Erin; Bird, Patrick; Gensic, Joseph; Wallace, F Morgan

2014-10-01

The performances of two DuPont BAX System PCR assays for detecting Salmonella on a variety of low-moisture soy ingredients were evaluated against the U. S. Food and Drug Administration's Bacteriological Analytical Manual (FDA BAM) method or the International Organization for Standardization (ISO) 6579 reference method. These evaluations were conducted as a single laboratory validation at an ISO 17025 accredited third-party laboratory. Validations were conducted on five soy ingredients: isolated soy protein (ISP), soy fiber, fluid soy lecithin, deoiled soy lecithin, and soy nuggets, using a paired-study design. The ISP was analyzed as both 25- and 375-g composite test portions, whereas all other sample matrices were analyzed as 375-g composite test portions. To evaluate 25-g test portions of ISP, the test material was inoculated using Salmonella enterica subsp. enterica serovar Mbandaka (Q Laboratories isolate 11031.1). Salmonella enterica subsp. enterica serovar Tennessee (Q Laboratories isolate 11031.3) was used for all other trials. For each trial of the method comparison, 25 samples were analyzed for each matrix: 5 uninoculated controls and 20 samples inoculated at low levels (0.2 to 2 CFU per test portion) that were targeted to achieve fractionally positive results (25 to 75%). Using McNemar's chi-square analysis, no significant difference at P ≥ 0.05 (χ(2) ≤ 3.84) was observed between the number of positives obtained by the BAX System and the reference methods for all five test matrices evaluated. These studies indicate that the BAX System PCR assays, in combination with the single buffered peptone water primary enrichment and subsequent brain heart infusion regrowth step, demonstrate equivalent sensitivity and robustness compared with the FDA BAM and ISO reference methods for both 25- and 375-g composite samples. Moreover, there was no observed reduction of sensitivity in the larger 375-g composite samples for all five matrices.

A Mobile Automated Tomographic Gamma Scanning System - 13231

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kirkpatrick, J.M.; LeBlanc, P.J.; Nakazawa, D.

2013-07-01

Canberra Industries have recently designed and built a new automated Tomographic Gamma Scanning (TGS) system for mobile deployment. The TGS technique combines high-resolution gamma spectroscopy with low spatial resolution 3-dimensional image reconstruction to provide increased accuracy over traditional approaches for the assay of non-uniform source distributions in low-to medium-density, non-heterogeneous matrices. Originally pioneered by R. Estep at Los Alamos National Laboratory (LANL), the TGS method has been further developed and commercialized by Canberra Industries in recent years. The present system advances the state of the art on several fronts: it is designed to be housed in a standard cargo transportmore » container for ease of transport, allowing waste characterization at multiple facilities under the purview of a single operator. Conveyor feed, drum rotator, and detector and collimator positioning mechanisms operated by programmable logic control (PLC) allow automated batch mode operation. The variable geometry settings can accommodate a wide range of waste packaging, including but not limited to standard 220 liter drums, 380 liter overpack drums, and smaller 20 liter cans. A 20 mCi Eu-152 transmission source provides attenuation corrections for drum matrices up to 1 g/cm{sup 3} in TGS mode; the system can be operated in Segmented Gamma Scanning (SGS) mode to measure higher density drums. To support TGS assays at higher densities, the source shield is sufficient to house an alternate Co-60 transmission source of higher activity, up to 250 mCi. An automated shutter and attenuator assembly is provided for operating the system with a dual intensity transmission source. The system's 1500 kg capacity rotator turntable can handle heavy containers such as concrete lined 380 liter overpack drums. Finally, data acquisition utilizes Canberra's Broad Energy Germanium (BEGE) detector and Lynx MCA, with 32 k channels, providing better than 0.1 keV/channel resolution to support both isotopic analysis with the MGA/MGAU software and a wide 3 MeV dynamic range. The calibration and verification of the system is discussed, and quantitative results are presented for a variety of drum types and matrices. (authors)« less

The ELPA library: scalable parallel eigenvalue solutions for electronic structure theory and computational science.

PubMed

Marek, A; Blum, V; Johanni, R; Havu, V; Lang, B; Auckenthaler, T; Heinecke, A; Bungartz, H-J; Lederer, H

2014-05-28

Obtaining the eigenvalues and eigenvectors of large matrices is a key problem in electronic structure theory and many other areas of computational science. The computational effort formally scales as O(N(3)) with the size of the investigated problem, N (e.g. the electron count in electronic structure theory), and thus often defines the system size limit that practical calculations cannot overcome. In many cases, more than just a small fraction of the possible eigenvalue/eigenvector pairs is needed, so that iterative solution strategies that focus only on a few eigenvalues become ineffective. Likewise, it is not always desirable or practical to circumvent the eigenvalue solution entirely. We here review some current developments regarding dense eigenvalue solvers and then focus on the Eigenvalue soLvers for Petascale Applications (ELPA) library, which facilitates the efficient algebraic solution of symmetric and Hermitian eigenvalue problems for dense matrices that have real-valued and complex-valued matrix entries, respectively, on parallel computer platforms. ELPA addresses standard as well as generalized eigenvalue problems, relying on the well documented matrix layout of the Scalable Linear Algebra PACKage (ScaLAPACK) library but replacing all actual parallel solution steps with subroutines of its own. For these steps, ELPA significantly outperforms the corresponding ScaLAPACK routines and proprietary libraries that implement the ScaLAPACK interface (e.g. Intel's MKL). The most time-critical step is the reduction of the matrix to tridiagonal form and the corresponding backtransformation of the eigenvectors. ELPA offers both a one-step tridiagonalization (successive Householder transformations) and a two-step transformation that is more efficient especially towards larger matrices and larger numbers of CPU cores. ELPA is based on the MPI standard, with an early hybrid MPI-OpenMPI implementation available as well. Scalability beyond 10,000 CPU cores for problem sizes arising in the field of electronic structure theory is demonstrated for current high-performance computer architectures such as Cray or Intel/Infiniband. For a matrix of dimension 260,000, scalability up to 295,000 CPU cores has been shown on BlueGene/P.

Resolution, sensitivity, and in vivo application of high-resolution computed tomography for titanium-coated polymethyl methacrylate (PMMA) dental implants.

PubMed

Cuijpers, Vincent M J I; Jaroszewicz, Jacub; Anil, Sukumaran; Al Farraj Aldosari, Abdullah; Walboomers, X Frank; Jansen, John A

2014-03-01

The aims of this study were (i) to determine the spatial resolution and sensitivity of micro- versus nano-computed tomography (CT) techniques and (ii) to validate micro- versus nano-CT in a dog dental implant model, comparative to histological analysis. To determine spatial resolution and sensitivity, standardized reference samples containing standardized nano- and microspheres were prepared in polymer and ceramic matrices. Thereafter, 10 titanium-coated polymer dental implants (3.2 mm in Ø by 4 mm in length) were placed in the mandible of Beagle dogs. Both micro- and nano-CT, as well as histological analyses, were performed. The reference samples confirmed the high resolution of the nano-CT system, which was capable of revealing sub-micron structures embedded in radiodense matrices. The dog implantation study and subsequent statistical analysis showed equal values for bone area and bone-implant contact measurements between micro-CT and histology. However, because of the limited sample size and field of view, nano-CT was not rendering reliable data representative of the entire bone-implant specimen. Micro-CT analysis is an efficient tool to quantitate bone healing parameters at the bone-implant interface, especially when using titanium-coated PMMA implants. Nano-CT is not suitable for such quantification, but reveals complementary morphological information rivaling histology, yet with the advantage of a 3D visualization. © 2013 John Wiley & Sons A/S. Published by Blackwell Publishing Ltd.

A strategy for extending the applicability of a validated plasma calibration curve to quantitative measurements in multiple tissue homogenate samples: a case study from a rat tissue distribution study of JI-101, a triple kinase inhibitor.

PubMed

Gurav, Sandip Dhondiram; Jeniffer, Sherine; Punde, Ravindra; Gilibili, Ravindranath Reddy; Giri, Sanjeev; Srinivas, Nuggehally R; Mullangi, Ramesh

2012-04-01

A general practice in bioanalysis is that, whatever the biological matrix the analyte is being quantified in, the validation is performed in the same matrix as per regulatory guidelines. In this paper, we are presenting the applicability of a validated LC-MS/MS method in rat plasma for JI-101, to estimate the concentrations of JI-101 in various tissues that were harvested in a rat tissue distribution study. A simple protein precipitation technique was used to extract JI-101 and internal standard from the tissue homogenates. The recovery of JI-101 in all the matrices was found to be >70%. Chromatographic separation was achieved using a binary gradient using mobile phase A (acetonitrile) and B (0.2% formic acid in water) at a flow rate of 0.30 mL/min on a Prodigy ODS column with a total run time of 4.0 min. The MS/MS ion transitions monitored were 466.1 → 265 for JI-101 and 180.1 → 110.1 for internal standard. The linearity range was 5.02-4017 ng/mL. The JI-101 levels were quantifiable in the various tissue samples harvested in this study. Therefore, the use of a previously validated JI-101 assay in plasma circumvented the tedious process of method development/validation in various tissue matrices. Copyright © 2011 John Wiley & Sons, Ltd.

Characterization of the rat exploratory behavior in the elevated plus-maze with Markov chains.

PubMed

Tejada, Julián; Bosco, Geraldine G; Morato, Silvio; Roque, Antonio C

2010-11-30

The elevated plus-maze is an animal model of anxiety used to study the effect of different drugs on the behavior of the animal. It consists of a plus-shaped maze with two open and two closed arms elevated 50cm from the floor. The standard measures used to characterize exploratory behavior in the elevated plus-maze are the time spent and the number of entries in the open arms. In this work, we use Markov chains to characterize the exploratory behavior of the rat in the elevated plus-maze under three different conditions: normal and under the effects of anxiogenic and anxiolytic drugs. The spatial structure of the elevated plus-maze is divided into squares, which are associated with states of a Markov chain. By counting the frequencies of transitions between states during 5-min sessions in the elevated plus-maze, we constructed stochastic matrices for the three conditions studied. The stochastic matrices show specific patterns, which correspond to the observed behaviors of the rat under the three different conditions. For the control group, the stochastic matrix shows a clear preference for places in the closed arms. This preference is enhanced for the anxiogenic group. For the anxiolytic group, the stochastic matrix shows a pattern similar to a random walk. Our results suggest that Markov chains can be used together with the standard measures to characterize the rat behavior in the elevated plus-maze. Copyright © 2010 Elsevier B.V. All rights reserved.

Quantification of VX Nerve Agent in Various Food Matrices by Solid-Phase Extraction Ultra-Performance Liquid ChromatographyTime-of-Flight Mass Spectrometry

DTIC Science & Technology

2016-04-01

QUANTIFICATION OF VX NERVE AGENT IN VARIOUS FOOD MATRICES BY SOLID-PHASE EXTRACTION ULTRA-PERFORMANCE...TITLE AND SUBTITLE Quantification of VX Nerve Agent in Various Food Matrices by Solid-Phase Extraction Ultra-Performance Liquid Chromatography... food matrices. The mixed-mode cation exchange (MCX) sorbent and Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) methods were used for

Novel image compression-encryption hybrid algorithm based on key-controlled measurement matrix in compressive sensing

NASA Astrophysics Data System (ADS)

Zhou, Nanrun; Zhang, Aidi; Zheng, Fen; Gong, Lihua

2014-10-01

The existing ways to encrypt images based on compressive sensing usually treat the whole measurement matrix as the key, which renders the key too large to distribute and memorize or store. To solve this problem, a new image compression-encryption hybrid algorithm is proposed to realize compression and encryption simultaneously, where the key is easily distributed, stored or memorized. The input image is divided into 4 blocks to compress and encrypt, then the pixels of the two adjacent blocks are exchanged randomly by random matrices. The measurement matrices in compressive sensing are constructed by utilizing the circulant matrices and controlling the original row vectors of the circulant matrices with logistic map. And the random matrices used in random pixel exchanging are bound with the measurement matrices. Simulation results verify the effectiveness, security of the proposed algorithm and the acceptable compression performance.

Intrinsic character of Stokes matrices

NASA Astrophysics Data System (ADS)

Gagnon, Jean-François; Rousseau, Christiane

2017-02-01

Two germs of linear analytic differential systems x k + 1Y‧ = A (x) Y with a non-resonant irregular singularity are analytically equivalent if and only if they have the same eigenvalues and equivalent collections of Stokes matrices. The Stokes matrices are the transition matrices between sectors on which the system is analytically equivalent to its formal normal form. Each sector contains exactly one separating ray for each pair of eigenvalues. A rotation in S allows supposing that R+ lies in the intersection of two sectors. Reordering of the coordinates of Y allows ordering the real parts of the eigenvalues, thus yielding triangular Stokes matrices. However, the choice of the rotation in x is not canonical. In this paper we establish how the collection of Stokes matrices depends on this rotation, and hence on a chosen order of the projection of the eigenvalues on a line through the origin.

Surveying the quantum group symmetries of integrable open spin chains

NASA Astrophysics Data System (ADS)

Nepomechie, Rafael I.; Retore, Ana L.

2018-05-01

Using anisotropic R-matrices associated with affine Lie algebras g ˆ (specifically, A2n(2), A2n-1 (2) , Bn(1), Cn(1), Dn(1)) and suitable corresponding K-matrices, we construct families of integrable open quantum spin chains of finite length, whose transfer matrices are invariant under the quantum group corresponding to removing one node from the Dynkin diagram of g ˆ . We show that these transfer matrices also have a duality symmetry (for the cases Cn(1) and Dn(1)) and additional Z2 symmetries that map complex representations to their conjugates (for the cases A2n-1 (2) , Bn(1) and Dn(1)). A key simplification is achieved by working in a certain "unitary" gauge, in which only the unbroken symmetry generators appear. The proofs of these symmetries rely on some new properties of the R-matrices. We use these symmetries to explain the degeneracies of the transfer matrices.

15 CFR 255.5 - Progress reports.

Code of Federal Regulations, 2012 CFR

2012-01-01

... STANDARDS AND TECHNOLOGY, DEPARTMENT OF COMMERCE FELLOWSHIPS AND RESEARCH ASSOCIATES FELLOWSHIPS IN LABORATORY STANDARDIZATION AND TESTING FOR QUALIFIED CITIZENS OF OTHER AMERICAN REPUBLICS § 255.5 Progress... & Technology may determine. [13 FR 8374, Dec. 28, 1948, as amended at 55 FR 38316, Sept. 18, 1990] ...

15 CFR 255.5 - Progress reports.

Code of Federal Regulations, 2011 CFR

2011-01-01

... STANDARDS AND TECHNOLOGY, DEPARTMENT OF COMMERCE FELLOWSHIPS AND RESEARCH ASSOCIATES FELLOWSHIPS IN LABORATORY STANDARDIZATION AND TESTING FOR QUALIFIED CITIZENS OF OTHER AMERICAN REPUBLICS § 255.5 Progress... & Technology may determine. [13 FR 8374, Dec. 28, 1948, as amended at 55 FR 38316, Sept. 18, 1990] ...

15 CFR 255.5 - Progress reports.

Code of Federal Regulations, 2014 CFR

2014-01-01

... STANDARDS AND TECHNOLOGY, DEPARTMENT OF COMMERCE FELLOWSHIPS AND RESEARCH ASSOCIATES FELLOWSHIPS IN LABORATORY STANDARDIZATION AND TESTING FOR QUALIFIED CITIZENS OF OTHER AMERICAN REPUBLICS § 255.5 Progress... & Technology may determine. [13 FR 8374, Dec. 28, 1948, as amended at 55 FR 38316, Sept. 18, 1990] ...

15 CFR 255.5 - Progress reports.

Code of Federal Regulations, 2010 CFR

2010-01-01

... STANDARDS AND TECHNOLOGY, DEPARTMENT OF COMMERCE FELLOWSHIPS AND RESEARCH ASSOCIATES FELLOWSHIPS IN LABORATORY STANDARDIZATION AND TESTING FOR QUALIFIED CITIZENS OF OTHER AMERICAN REPUBLICS § 255.5 Progress... & Technology may determine. [13 FR 8374, Dec. 28, 1948, as amended at 55 FR 38316, Sept. 18, 1990] ...

15 CFR 255.5 - Progress reports.

Code of Federal Regulations, 2013 CFR

2013-01-01

... STANDARDS AND TECHNOLOGY, DEPARTMENT OF COMMERCE FELLOWSHIPS AND RESEARCH ASSOCIATES FELLOWSHIPS IN LABORATORY STANDARDIZATION AND TESTING FOR QUALIFIED CITIZENS OF OTHER AMERICAN REPUBLICS § 255.5 Progress... & Technology may determine. [13 FR 8374, Dec. 28, 1948, as amended at 55 FR 38316, Sept. 18, 1990] ...

HiCRep: assessing the reproducibility of Hi-C data using a stratum-adjusted correlation coefficient

PubMed Central

Yang, Tao; Zhang, Feipeng; Yardımcı, Galip Gürkan; Song, Fan; Hardison, Ross C.; Noble, William Stafford; Yue, Feng; Li, Qunhua

2017-01-01

Hi-C is a powerful technology for studying genome-wide chromatin interactions. However, current methods for assessing Hi-C data reproducibility can produce misleading results because they ignore spatial features in Hi-C data, such as domain structure and distance dependence. We present HiCRep, a framework for assessing the reproducibility of Hi-C data that systematically accounts for these features. In particular, we introduce a novel similarity measure, the stratum adjusted correlation coefficient (SCC), for quantifying the similarity between Hi-C interaction matrices. Not only does it provide a statistically sound and reliable evaluation of reproducibility, SCC can also be used to quantify differences between Hi-C contact matrices and to determine the optimal sequencing depth for a desired resolution. The measure consistently shows higher accuracy than existing approaches in distinguishing subtle differences in reproducibility and depicting interrelationships of cell lineages. The proposed measure is straightforward to interpret and easy to compute, making it well-suited for providing standardized, interpretable, automatable, and scalable quality control. The freely available R package HiCRep implements our approach. PMID:28855260

Efficient sparse matrix-matrix multiplication for computing periodic responses by shooting method on Intel Xeon Phi

NASA Astrophysics Data System (ADS)

Stoykov, S.; Atanassov, E.; Margenov, S.

2016-10-01

Many of the scientific applications involve sparse or dense matrix operations, such as solving linear systems, matrix-matrix products, eigensolvers, etc. In what concerns structural nonlinear dynamics, the computations of periodic responses and the determination of stability of the solution are of primary interest. Shooting method iswidely used for obtaining periodic responses of nonlinear systems. The method involves simultaneously operations with sparse and dense matrices. One of the computationally expensive operations in the method is multiplication of sparse by dense matrices. In the current work, a new algorithm for sparse matrix by dense matrix products is presented. The algorithm takes into account the structure of the sparse matrix, which is obtained by space discretization of the nonlinear Mindlin's plate equation of motion by the finite element method. The algorithm is developed to use the vector engine of Intel Xeon Phi coprocessors. It is compared with the standard sparse matrix by dense matrix algorithm and the one developed by Intel MKL and it is shown that by considering the properties of the sparse matrix better algorithms can be developed.

Determination of alkylphenol and alkylphenolethoxylates in biota by liquid chromatography with detection by tandem mass spectrometry and fluorescence spectroscopy

USGS Publications Warehouse

Schmitz-Afonso, I.; Loyo-Rosales, J.E.; de la Paz Aviles, M.; Rattner, B.A.; Rice, C.P.

2003-01-01

A quantitative method for the simultaneous determination of octylphenol, nonylphenol and the corresponding ethoxylates (1 to 5) in biota is presented. Extraction methods were developed for egg and fish matrices based on accelerated solvent extraction followed by a solid-phase extraction cleanup, using octadecylsilica or aminopropyl cartridges. Identification and quantitation were accomplished by liquid chromatography-electrospray tandem mass spectrometry (LC-MS-MS) and compared to the traditional liquid chromatography with fluorescence spectroscopy detection. LC-MS-MS provides high sensitivity and specificity required for these complex matrices and an accurate quantitation with the use of 13C-labeled internal standards. Quantitation limits by LC-MS-MS ranged from 4 to 12 ng/g in eggs, and from 6 to 22 ng/g in fish samples. These methods were successfully applied to osprey eggs from the Chesapeake Bay and fish from the Great Lakes area. Total levels found in osprey egg samples were up to 18 ng/g wet mass and as high as 8.2 ug/g wet mass in the fish samples.

Analytical study of azadirachtin and 3-tigloylazadirachtol residues in foliage and phloem of hardwood tree species by liquid chromatography-electrospray mass spectrometry.

PubMed

Grimalt, Susana; Thompson, Dean G; Coppens, Melanie; Chartrand, Derek T; Shorney, Thomas; Meating, Joe; Scarr, Taylor

2011-08-10

A rapid and sensitive LC-ESI-MS method has been developed and validated for the quantitation of azadirachtin and 3-tigloylazadirachtol in deciduous tree matrices. The method involves automated extraction and simultaneous cleanup using an accelerated solvent technique with the matrix dispersed in solid phase over a layer of primary-secondary amine silica. The limits of quantification were 0.02 mg/kg for all matrices with the exception of Norway maple foliage (0.05 mg/kg). Validation at three levels (0.02, 0.1, and 1 mg/kg), demonstrated satisfactory recoveries (71-103%) with relative standard deviation <20%. Two in-source fragment ions were used for confirmation at levels above 0.1 mg/kg. Over a period of several months, quality control analyses showed the technique to be robust and effective in tracking the fate of these natural botanical insecticides following systemic injection into various tree species for control of invasive insect pest species such as the emerald ash borer and Asian longhorned beetle.

Amesos2 and Belos: Direct and Iterative Solvers for Large Sparse Linear Systems

DOE PAGES

Bavier, Eric; Hoemmen, Mark; Rajamanickam, Sivasankaran; ...

2012-01-01

Solvers for large sparse linear systems come in two categories: direct and iterative. Amesos2, a package in the Trilinos software project, provides direct methods, and Belos, another Trilinos package, provides iterative methods. Amesos2 offers a common interface to many different sparse matrix factorization codes, and can handle any implementation of sparse matrices and vectors, via an easy-to-extend C++ traits interface. It can also factor matrices whose entries have arbitrary “Scalar” type, enabling extended-precision and mixed-precision algorithms. Belos includes many different iterative methods for solving large sparse linear systems and least-squares problems. Unlike competing iterative solver libraries, Belos completely decouples themore » algorithms from the implementations of the underlying linear algebra objects. This lets Belos exploit the latest hardware without changes to the code. Belos favors algorithms that solve higher-level problems, such as multiple simultaneous linear systems and sequences of related linear systems, faster than standard algorithms. The package also supports extended-precision and mixed-precision algorithms. Together, Amesos2 and Belos form a complete suite of sparse linear solvers.« less

Esophageal tissue engineering: Current status and perspectives.

PubMed

Poghosyan, T; Catry, J; Luong-Nguyen, M; Bruneval, P; Domet, T; Arakelian, L; Sfeir, R; Michaud, L; Vanneaux, V; Gottrand, F; Larghero, J; Cattan, P

2016-02-01

Tissue engineering, which consists of the combination and in vivo implantation of elements required for tissue remodeling toward a specific organ phenotype, could be an alternative for classical techniques of esophageal replacement. The current hybrid approach entails creation of an esophageal substitute composed of an acellular matrix and autologous epithelial and muscle cells provides the most successful results. Current research is based on the use of mesenchymal stem cells, whose potential for differentiation and proangioogenic, immune-modulator and anti-inflammatory properties are important assets. In the near future, esophageal substitutes could be constructed from acellular "intelligent matrices" that contain the molecules necessary for tissue regeneration; this should allow circumvention of the implantation step and still obtain standardized in vivo biological responses. At present, tissue engineering applications to esophageal replacement are limited to enlargement plasties with absorbable, non-cellular matrices. Nevertheless, the application of existing clinical techniques for replacement of other organs by tissue engineering in combination with a multiplication of translational research protocols for esophageal replacement in large animals should soon pave the way for health agencies to authorize clinical trials. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Analysis of processing contaminants in edible oils. Part 2. Liquid chromatography-tandem mass spectrometry method for the direct detection of 3-monochloropropanediol and 2-monochloropropanediol diesters.

PubMed

MacMahon, Shaun; Begley, Timothy H; Diachenko, Gregory W

2013-05-22

A method was developed and validated for the detection of fatty acid diesters of 2-monochloropropanediol (2-MCPD) and 3-monochloropropanediol (3-MCPD) in edible oils. These analytes are potentially carcinogenic chemical contaminants formed during edible oil processing. After separation from oil matrices using a two-step solid-phase extraction (SPE) procedure, the target compounds are quantitated using liquid chromatography-tandem mass spectrometry (LC-MS/MS) with electrospray ionization (ESI). The first chromatographic conditions have been developed that separate intact diesters of 2-MCPD and 3-MCPD, allowing for their individual quantitation. The method has been validated for 28 3-MCPD diesters of lauric, myristic, palmitic, linolenic, linoleic, oleic, and stearic acids in coconut, olive, and palm oils, as well as 3 2-MCPD diesters, using an external calibration curve. The range of average recoveries and relative standard deviations (RSDs) across the three oil matrices at three spiking concentrations are 88-118% (2-16% RSD) with maximum limits of quantitation of 30 ng/g (ppb).

Comparative study of different clean-up techniques for the determination of λ-cyhalothrin and cypermethrin in palm oil matrices by gas chromatography with electron capture detection.

PubMed

Muhamad, Halimah; Zainudin, Badrul Hisyam; Abu Bakar, Nor Kartini

2012-10-15

Solid phase extraction (SPE) and dispersive solid-phase extraction (d-SPE) were compared and evaluated for the determination of λ-cyhalothrin and cypermethrin in palm oil matrices by gas chromatography with an electron capture detector (GC-ECD). Several SPE sorbents such as graphitised carbon black (GCB), primary secondary amine (PSA), C(18), silica, and florisil were tested in order to minimise fat residues. The results show that mixed sorbents using GCB and PSA obtained cleaner extracts than a single GCB and PSA sorbents. The average recoveries obtained for each pesticide ranged between 81% and 114% at five fortification levels with the relative standard deviation of less than 7% in all cases. The limits of detection for these pesticides were ranged between 0.025 and 0.05 μg/g. The proposed method was applied successfully for the residue determination of both λ-cyhalothrin and cypermethrin in crude palm oil samples obtained from local mills throughout Malaysia. Copyright © 2012 Elsevier Ltd. All rights reserved.

Efficient linear algebra routines for symmetric matrices stored in packed form.

PubMed

Ahlrichs, Reinhart; Tsereteli, Kakha

2002-01-30

Quantum chemistry methods require various linear algebra routines for symmetric matrices, for example, diagonalization or Cholesky decomposition for positive matrices. We present a small set of these basic routines that are efficient and minimize memory requirements.

Progress, innovation and regulatory science in drug development: the politics of international standard-setting.

PubMed

Abraham, John; Reed, Tim

2002-06-01

This paper examines international standard-setting in the toxicology of pharmaceuticals during the 1990s, which has involved both the pharmaceutical industry and regulatory agencies in an organization known as the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH). The analysis shows that the relationships between innovation, regulatory science and 'progress' may be more complex and controversial than is often assumed. An assessment of the ICH's claims about the implications of 'technical' harmonization of drug-testing standards for the maintenance of drug safety, via toxicological testing, and the delivery of therapeutic progress, via innovation, is presented. By demonstrating that there is not a technoscientific validity for these claims, it is argued that, within the ICH, a discourse of technological innovation and scientific progress has been used by regulatory agencies and prominent parts of the transnational pharmaceutical industry to legitimize the lowering and loosening of toxicological standards for drug testing. The mobilization and acceptance of this discourse are shown to be pivotal to the ICH's transformation of reductions in safety standards, which are apparently against the interests of patients and public health, into supposed therapeutic benefits derived from promises of greater access to more innovative drug products. The evidence suggests that it is highly implausible that these reductions in the standards of regulatory toxicology are consistent with therapeutic progress for patients, and highlights a worrying aspect embedded in the 'technical trajectories' of regulatory science.

ESTIMATION OF FUNCTIONALS OF SPARSE COVARIANCE MATRICES.

PubMed

Fan, Jianqing; Rigollet, Philippe; Wang, Weichen

High-dimensional statistical tests often ignore correlations to gain simplicity and stability leading to null distributions that depend on functionals of correlation matrices such as their Frobenius norm and other ℓ r norms. Motivated by the computation of critical values of such tests, we investigate the difficulty of estimation the functionals of sparse correlation matrices. Specifically, we show that simple plug-in procedures based on thresholded estimators of correlation matrices are sparsity-adaptive and minimax optimal over a large class of correlation matrices. Akin to previous results on functional estimation, the minimax rates exhibit an elbow phenomenon. Our results are further illustrated in simulated data as well as an empirical study of data arising in financial econometrics.

ESTIMATION OF FUNCTIONALS OF SPARSE COVARIANCE MATRICES

PubMed Central

Fan, Jianqing; Rigollet, Philippe; Wang, Weichen

2016-01-01

High-dimensional statistical tests often ignore correlations to gain simplicity and stability leading to null distributions that depend on functionals of correlation matrices such as their Frobenius norm and other ℓr norms. Motivated by the computation of critical values of such tests, we investigate the difficulty of estimation the functionals of sparse correlation matrices. Specifically, we show that simple plug-in procedures based on thresholded estimators of correlation matrices are sparsity-adaptive and minimax optimal over a large class of correlation matrices. Akin to previous results on functional estimation, the minimax rates exhibit an elbow phenomenon. Our results are further illustrated in simulated data as well as an empirical study of data arising in financial econometrics. PMID:26806986

A field study of selected U.S. Geological Survey analytical methods for measuring pesticides in filtered stream water, June - September 2012

USGS Publications Warehouse

Martin, Jeffrey D.; Norman, Julia E.; Sandstrom, Mark W.; Rose, Claire E.

2017-09-06

U.S. Geological Survey monitoring programs extensively used two analytical methods, gas chromatography/mass spectrometry and liquid chromatography/mass spectrometry, to measure pesticides in filtered water samples during 1992–2012. In October 2012, the monitoring programs began using direct aqueous-injection liquid chromatography tandem mass spectrometry as a new analytical method for pesticides. The change in analytical methods, however, has the potential to inadvertently introduce bias in analysis of datasets that span the change.A field study was designed to document performance of the new method in a variety of stream-water matrices and to quantify any potential changes in measurement bias or variability that could be attributed to changes in analytical methods. The goals of the field study were to (1) summarize performance (bias and variability of pesticide recovery) of the new method in a variety of stream-water matrices; (2) compare performance of the new method in laboratory blank water (laboratory reagent spikes) to that in a variety of stream-water matrices; (3) compare performance (analytical recovery) of the new method to that of the old methods in a variety of stream-water matrices; (4) compare pesticide detections and concentrations measured by the new method to those of the old methods in a variety of stream-water matrices; (5) compare contamination measured by field blank water samples in old and new methods; (6) summarize the variability of pesticide detections and concentrations measured by the new method in field duplicate water samples; and (7) identify matrix characteristics of environmental water samples that adversely influence the performance of the new method. Stream-water samples and a variety of field quality-control samples were collected at 48 sites in the U.S. Geological Survey monitoring networks during June–September 2012. Stream sites were located across the United States and included sites in agricultural and urban land-use settings, as well as sites on major rivers.The results of the field study identified several challenges for the analysis and interpretation of data analyzed by both old and new methods, particularly when data span the change in methods and are combined for analysis of temporal trends in water quality. The main challenges identified are large (greater than 30 percent), statistically significant differences in analytical recovery, detection capability, and (or) measured concentrations for selected pesticides. These challenges are documented and discussed, but specific guidance or statistical methods to resolve these differences in methods are beyond the scope of the report. The results of the field study indicate that the implications of the change in analytical methods must be assessed individually for each pesticide and method.Understanding the possible causes of the systematic differences in concentrations between methods that remain after recovery adjustment might be necessary to determine how to account for the differences in data analysis. Because recoveries for each method are independently determined from separate reference standards and spiking solutions, the differences might be due to an error in one of the reference standards or solutions or some other basic aspect of standard procedure in the analytical process. Further investigation of the possible causes is needed, which will lead to specific decisions on how to compensate for these differences in concentrations in data analysis. In the event that further investigations do not provide insight into the causes of systematic differences in concentrations between methods, the authors recommend continuing to collect and analyze paired environmental water samples by both old and new methods. This effort should be targeted to seasons, sites, and expected concentrations to supplement those concentrations already assessed and to compare the ongoing analytical recovery of old and new methods to those observed in the summer and fall of 2012.

A Study on the Application of the Extended Matrices Based on TRIZ in Constructing a Collaborative Model of Enterprise Network

NASA Astrophysics Data System (ADS)

Yang, Yan; Shao, Yunfei; Tang, Xiaowo

Based on mass related literature on enterprise network, the key influence factors are reduced to Trust, Control, Relationship and Interaction. Meanwhile, the specific contradiction matrices, judgment matrices and strategy collections based on TRIZ are constructed which make the connotation of contradiction matrices in TRIZ extended. Finally they are applied to the construction of the collaborative model on enterprise network based on Multi Agent System (MAS).