Science.gov

Sample records for revisited matrix evaluation

  1. Algebraic construction of the Darboux matrix revisited

    NASA Astrophysics Data System (ADS)

    Cieśliński, Jan L.

    2009-10-01

    We present algebraic construction of Darboux matrices for 1+1-dimensional integrable systems of nonlinear partial differential equations with a special stress on the nonisospectral case. We discuss different approaches to the Darboux-Bäcklund transformation, based on different λ-dependences of the Darboux matrix: polynomial, sum of partial fractions or the transfer matrix form. We derive symmetric N-soliton formulae in the general case. The matrix spectral parameter and dressing actions in loop groups are also discussed. We describe reductions to twisted loop groups, unitary reductions, the matrix Lax pair for the KdV equation and reductions of chiral models (harmonic maps) to SU(n) and to Grassmann spaces. We show that in the KdV case the nilpotent Darboux matrix generates the binary Darboux transformation. The paper is intended as a review of known results (usually presented in a novel context) but some new results are included as well, e.g., general compact formulae for N-soliton surfaces and linear and bilinear constraints on the nonisospectral Lax pair matrices which are preserved by Darboux transformations.

  2. Extracellular Matrix Revisited: Roles in Tissue Engineering

    PubMed Central

    2016-01-01

    The extracellular matrix (ECM) is a heterogeneous, connective network composed of fibrous glycoproteins that coordinate in vivo to provide the physical scaffolding, mechanical stability, and biochemical cues necessary for tissue morphogenesis and homeostasis. This review highlights some of the recently raised aspects of the roles of the ECM as related to the fields of biophysics and biomedical engineering. Fundamental aspects of focus include the role of the ECM as a basic cellular structure, for novel spontaneous network formation, as an ideal scaffold in tissue engineering, and its essential contribution to cell sheet technology. As these technologies move from the laboratory to clinical practice, they are bound to shape the vast field of tissue engineering for medical transplantations. PMID:27230457

  3. Evaluation of metal matrix composites

    NASA Technical Reports Server (NTRS)

    Okelly, K. P.

    1971-01-01

    The results of an evaluation of candidate metal-matrix composite materials for shuttle space radiators mounted to external structure are presented. The evaluation was specifically applicable to considerations of the manufacturing and properties of a potential space radiator. Two candidates, boron/aluminum and graphite/aluminum were obtained or made in various forms and tested in sufficient depth to allow selection of one of the two for future scale-up programs. The effort accomplished on this program verified that aluminum reinforced with boron was within the state-of-the-art in industry and possessed properties usable in the external skin areas available for shuttle radiators where re-entry temperatures will not exceed 800 F. It further demonstrated that graphite/aluminum has an apparently attractive future for space applications but requires extension development prior to scale-up.

  4. Evaluation Methods for Intelligent Tutoring Systems Revisited

    ERIC Educational Resources Information Center

    Greer, Jim; Mark, Mary

    2016-01-01

    The 1993 paper in "IJAIED" on evaluation methods for Intelligent Tutoring Systems (ITS) still holds up well today. Basic evaluation techniques described in that paper remain in use. Approaches such as kappa scores, simulated learners and learning curves are refinements on past evaluation techniques. New approaches have also arisen, in…

  5. Micromechanical Evaluation of Ceramic Matrix Composites

    DTIC Science & Technology

    1991-02-01

    Materials Sciences Corporation AD-A236 756 M.hM. 9 1 0513 IEIN HIfINU IIl- DTIC JUN 06 1991 MICROMECHANICAL EVALUATION OF S 0 CERAMIC MATRIX COMPOSITES C...Classification) \\() Micromechanical Evaluation of Ceramic Matrix Composites ) 12. PERSONAL AUTHOR(S) C-F. Yen, Z. Hashin, C. Laird, B.W. Rosen, Z. Wang 13a. TYPE...and strengthen the ceramic composites. In this task, various possibilities of crack propagation in unidirectional ceramic matrix composites under

  6. Matrix evaluation of science objectives

    NASA Technical Reports Server (NTRS)

    Wessen, Randii R.

    1994-01-01

    The most fundamental objective of all robotic planetary spacecraft is to return science data. To accomplish this, a spacecraft is fabricated and built, software is planned and coded, and a ground system is designed and implemented. However, the quantitative analysis required to determine how the collection of science data drives ground system capabilities has received very little attention. This paper defines a process by which science objectives can be quantitatively evaluated. By applying it to the Cassini Mission to Saturn, this paper further illustrates the power of this technique. The results show which science objectives drive specific ground system capabilities. In addition, this process can assist system engineers and scientists in the selection of the science payload during pre-project mission planning; ground system designers during ground system development and implementation; and operations personnel during mission operations.

  7. Evaluation of lymphangiogenesis in acellular dermal matrix

    PubMed Central

    Cherubino, Mario; Pellegatta, Igor; Tamborini, Federico; Cerati, Michele; Sessa, Fausto; Valdatta, Luigi

    2014-01-01

    Introduction: Much attention has been directed towards understanding the phenomena of angiogenesis and lymphangiogenesis in wound healing. Thanks to the manifold dermal substitute available nowadays, wound treatment has improved greatly. Many studies have been published about angiogenesis and cell invasion in INTEGRA®. On the other hand, the development of the lymphatic network in acellular dermal matrix (ADM) is a more obscure matter. In this article, we aim to characterize the different phases of host cell invasion in ADM. Special attention was given to lymphangiogenic aspects. Materials and Methods: Among 57 rats selected to analyse the role of ADM in lymphangiogenesis, we created four groups. We performed an excision procedure on both thighs of these rats: On the left one we did not perform any action except repairing the borders of the wound; while on the right one we used INTEGRA® implant. The excision biopsy was performed at four different times: First group after 7 days, second after 14 days, third after 21 days and fourth after 28 days. For our microscopic evaluation, we used the classical staining technique of haematoxylin and eosin and a semi-quantitative method in order to evaluate cellularity counts. To assess angiogenesis and lymphangiogenesis development we employed PROX-1 Ab and CD31/PECAM for immunohistochemical analysis. Results: We found remarkable wound contraction in defects that healed by secondary intention while minor wound contraction was observed in defects treated with ADM. At day 7, optical microscopy revealed a more plentiful cellularity in the granulation tissue compared with the dermal regeneration matrix. The immunohistochemical process highlighted vascular and lymphatic cells in both groups. After 14 days a high grade of fibrosis was noticeable in the non-treated group. At day 21, both lymphatic and vascular endothelial cells were better developed in the group with a dermal matrix application. At day 28, lymphatic endothelial

  8. Revisiting the quark-lepton complementarity and triminimal parametrization of neutrino mixing matrix

    SciTech Connect

    Kang, Sin Kyu

    2011-05-01

    We examine how a parametrization of neutrino mixing matrix reflecting quark-lepton complementarity can be probed by considering phase-averaged oscillation probabilities, flavor composition of neutrino fluxes coming from atmospheric and astrophysical neutrinos and lepton flavor violating radiative decays. We discuss some distinct features of the parametrization by comparing the triminimal parametrization of perturbations to the tribimaximal neutrino mixing matrix.

  9. Great Ideas Revisited. Techniques for Evaluating Training Programs. Revisiting Kirkpatrick's Four-Level Model.

    ERIC Educational Resources Information Center

    Kirkpatrick, Donald

    1996-01-01

    Kirkpatrick reviews his 1959 article presenting his four-level model of evaluation. He suggests that training professionals should evaluate their programs and understanding those four levels is a good start. The text of the original article is included. (JOW)

  10. Conducted Emission Evaluation for Direct Matrix Converters

    NASA Astrophysics Data System (ADS)

    Nothofer, A.; Tarisciotti, L.; Greedy, S.; Empringham, L.; De Lillo, L.; Degano, M.

    2016-05-01

    Matrix converters have been recently proposed as an alternative solution to the standard back-to-back converter in aerospace applications. However, Electromagnetic Interference (EMI), in particular, conducted emissions represent a critical aspect for this converter family. Direct Matrix Converter (DMC) are usually modelled only at the normal operating frequency, but for the research presented in this paper, the model is modified in order to include a detailed high frequency description, which is of interest for conducted emission studies.This paper analyzes the performance of DMC, when different control and modulation techniques are used. Experimental results are shown to validate the simulation models.

  11. Complicity Revisited: Balancing Stakeholder Input and Roles in Evaluation Use

    ERIC Educational Resources Information Center

    Sturges, Keith M.

    2015-01-01

    Drawing on a qualitative study of an educational reform and its external evaluation, I describe how a well-intentioned but poorly conceptualized evaluation helped perpetuate asymmetries in the generation and use of evaluation findings. This article explores this project's failure to clarify evaluator roles, identify intended users and expected…

  12. Evaluation of the Matrix Project. Interchange 77.

    ERIC Educational Resources Information Center

    McIvor, Gill; Moodie, Kristina

    The Matrix Project is a program that has been established in central Scotland with the aim of reducing the risk of offending and anti-social behavior among vulnerable children. The project provides a range of services to children between eight and 11 years of age who are at risk in the local authority areas of Clackmannanshire, Falkirk and…

  13. Lakatos Revisited.

    ERIC Educational Resources Information Center

    Court, Deborah

    1999-01-01

    Revisits and reviews Imre Lakatos' ideas on "Falsification and the Methodology of Scientific Research Programmes." Suggests that Lakatos' framework offers an insightful way of looking at the relationship between theory and research that is relevant not only for evaluating research programs in theoretical physics, but in the social…

  14. Entrepreneurship Education Evaluation: Revisiting Storey to Hunt for the "Heffalump"

    ERIC Educational Resources Information Center

    Henry, Colette

    2015-01-01

    Purpose: The purpose of this paper is to consider entrepreneurship education (EE) evaluation. Specifically, it explores some of the challenges involved in applying the "HEInnovate" tool, and considers ways in which its accuracy and value might be strengthened. Using Storey (2000) by way of reflective critique, the paper proposes an…

  15. Preventing Groupthink Revisited: Evaluating and Reforming Groups in Government.

    PubMed

    Hart

    1998-02-01

    This article critically examines Janis's recommendations for preventing groupthink in high-level policymaking. It puts forward three models of small group functioning in government, each of which highlights different dimensions of collegial policymaking and distinct criteria for evaluating group performance. Each model also inspires different proposals for groupthink prevention and improvement of group performance in general. Proposals for designing and managing high-level groups in government need to take into account these multiple perspectives. Furthermore, their proponents should be aware of the institutionalized and competitive context in which political decision groups operate. Evaluations of their performance and proposals for reforming them are inevitably tied up in this process. This has important implications for the feasibility of recommendations set forth by small group analysts. The article concludes with an agenda for increasing the policy relevance and practical feasibility of research on political decision groups. Copyright 1998 Academic Press.

  16. Evaluation of waterjet-machined metal matrix composite tensile specimens

    SciTech Connect

    Lavender, C.A.; Smith, M.T.

    1986-04-01

    Four magnesium/boron carbide metal matrix composite (MMC) tensile specimens fabricated using the waterjet machining method were evaluated in order to determine the effects of the waterjet material removal process on the composite material surface structure and properties. These results were then compared with data from material conventionally machined. Results showed that while waterjet cutting produces a rough surface finish and does not meet specified dimensional tolerances, the technique appears to be suitable for sectioning and rough machining of metal matrix composites.

  17. Imagistic evaluation of matrix bone interface

    NASA Astrophysics Data System (ADS)

    NegruÅ£iu, Meda L.; Sinescu, Cosmin; Manescu, Adrian; Topalǎ, Florin I.; Hoinoiu, Bogdan; MǎrcǎuÅ£eanu, Corina; Duma, Virgil; Bradu, Adrian; Podoleanu, Adrian G.

    2014-01-01

    The problematic elements of bone regenerative materials are represented by their quality control methods. The defects repaired by bone grafting material were evaluated by en face optical coherence tomography and by synchrotron radiation micro-CT. The images obtained by efOCT show defects in some of the investigated samples, at the bone interface with different osteoconductive bone substitutes and we were able to detect gaps as small as 50 μm. After the common synchrotron radiation micro-CT investigations, the slides were reconstructed and the 3D model was obtained. Along with the possibility of navigating inside the structure, one big advantage of this technique was pointed out: the remaining regenerative materials can be separated from the normal bone and the new bone can be visualized. Optical coherence tomography can be performed in vivo and can provide a qualitative and quantitative evaluation of the bone augmentation procedure.

  18. Evaluation of the Covariance Matrix of Estimated Resonance Parameters

    NASA Astrophysics Data System (ADS)

    Becker, B.; Capote, R.; Kopecky, S.; Massimi, C.; Schillebeeckx, P.; Sirakov, I.; Volev, K.

    2014-04-01

    In the resonance region nuclear resonance parameters are mostly obtained by a least square adjustment of a model to experimental data. Derived parameters can be mutually correlated through the adjustment procedure as well as through common experimental or model uncertainties. In this contribution we investigate four different methods to propagate the additional covariance caused by experimental or model uncertainties into the evaluation of the covariance matrix of the estimated parameters: (1) including the additional covariance into the experimental covariance matrix based on calculated or theoretical estimates of the data; (2) including the uncertainty affected parameter in the adjustment procedure; (3) evaluation of the full covariance matrix by Monte Carlo sampling of the common parameter; and (4) retroactively including the additional covariance by using the marginalization procedure of Habert et al.

  19. Evaluation of 2D ceramic matrix composites in aeroconvective environments

    NASA Technical Reports Server (NTRS)

    Riccitiello, Salvatore R.; Love, Wendell L.; Balter-Peterson, Aliza

    1992-01-01

    An evaluation is conducted of a novel ceramic-matrix composite (CMC) material system for use in the aeroconvective-heating environments encountered by the nose caps and wing leading edges of such aerospace vehicles as the Space Shuttle, during orbit-insertion and reentry from LEO. These CMCs are composed of an SiC matrix that is reinforced with Nicalon, Nextel, or carbon refractory fibers in a 2D architecture. The test program conducted for the 2D CMCs gave attention to their subsurface oxidation.

  20. Evaluating wilderness recreational opportunities: application of an impact matrix

    USGS Publications Warehouse

    Stohlgren, Thomas J.; Parsons, David J.

    1992-01-01

    An inventory of the severity and spatial distribution of wilderness campsite impacts in Sequoia and Kings Canyon National Parks identified a total of 273 distinct nodes of campsites or “management areas.” A campsite impact matrix was developed to evaluate management areas based on total impacts (correlated to the total area of campsite development) and the density, or concentration, of impacts relative to each area's potentially campable area. The matrix is used to quantify potential recreational opportunities for wilderness visitors in a spectrum from areas offering low impact-dispersed camping to those areas offering high impact-concentrated camping. Wilderness managers can use this type of information to evaluate use distribution patterns, identify areas to increase or decrease use, and to identify areas needing site-specific regulations (e.g., one-night camping limits) to preserve wilderness resources and guarantee outstanding opportunities for solitude.

  1. Revisiting the block method for evaluating thermal conductivities of clay and granite

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Determination of thermal conductivities of porous media using the contact method is revisited and revalidated with consideration of thermal contact resistance. Problems that limit the accuracy of determination of thermal conductivities of porous media are discussed. Thermal conductivities of granite...

  2. Nonnegative matrix factorization for the identification of EMG finger movements: evaluation using matrix analysis.

    PubMed

    Naik, Ganesh R; Nguyen, Hung T

    2015-03-01

    Surface electromyography (sEMG) is widely used in evaluating the functional status of the hand to assist in hand gesture recognition, prosthetics and rehabilitation applications. The sEMG is a noninvasive, easy to record signal of superficial muscles from the skin surface. Considering the nonstationary characteristics of sEMG, recent feature selection of hand gesture recognition using sEMG signals necessitate designers to use nonnegative matrix factorization (NMF)-based methods. This method exploits both the additive and sparse nature of signals by extracting accurate and reliable measurements of sEMG features using a minimum number of sensors. The testing has been conducted for simple and complex finger flexions using several experiments with artificial neural network classification scheme. It is shown, both by simulation and experimental studies, that the proposed algorithm is able to classify ten finger flexions (five simple and five complex finger flexions) recorded from two sEMG sensors up to 92% (95% for simple and 87% for complex flexions) accuracy. The recognition performances of simple and complex finger flexions are also validated with NMF permutation matrix analysis.

  3. Acousto-ultrasonic evaluation of ceramic matrix composite materials

    NASA Technical Reports Server (NTRS)

    Dosreis, Henrique L. M.

    1991-01-01

    Acousto-ultrasonic nondestructive evaluation of ceramic composite specimens with a lithium-alumino-silicate glass matrix reinforced with unidirectional silicon carbide (NICALON) fibers was conducted to evaluate their reserve of strength. Ceramic composite specimens with different amount of damage were prepared by four-point cyclic fatigue loading of the specimens at 500 C for a different number of cycles. The reserve of strength of the specimens was measured as the maximum bending stress recorded during four-pointed bending test with the load monotonically increased until failure occurs. It was observed that the reserve of strength did not correlate with the number of fatigue cycles. However, it was also observed that higher values of the stress wave factor measurements correspond to higher values of the reserve of strength test data. Therefore, these results show that the acousto-ultrasonic approach has the potential of being used to monitor damage and to estimate the reserve of strength of ceramic composites.

  4. Formulation and evaluation of floating matrix tablet of stavudine

    PubMed Central

    Prajapati, Pankaj H; Nakum, Vijay V; Patel, Chhagan N

    2012-01-01

    Background/Aim: The purpose of the study was to prolong the gastric residence time of stavudine by designing its floating tablets and to study the influence of different polymers on its release rate. Materials and Methods: The floating mix matrix tablets of stavudine were prepared by melt granulation method. Beeswax was used as hydrophobic meltable material. Hydroxypropyl methylcellulose (HPMC), sodium bicarbonate, and ethyl cellulose were used as matrixing agent, gas generating agent, and floating enhancer, respectively. The prepared tablets were evaluated for physicochemical parameters such as hardness, weight variation, friability, floating properties (floating lag time, total floating time), drug content, stability study, and in vitro drug release. The drug- polymer interaction was studied by Differential Scanning Calorimetry (DSC) thermal analysis and Fourier transform infared (FT-IR). Results: The floating lag time of all the formulations was within the prescribed limit (<3 min). All the formulations showed good matrix integrity and retarded the release of drug for 12 h except the formulation F5.The concentration of beeswax (X1), HPMC K4M (X2), and ethyl cellulose (X3) were selected as independent variables and drug release values at 1 (Q1), at 6 (Q6) and at 12 h (Q12) as dependent variables. Formulation F7 was selected as an optimum formulation as it showed more similarity in dissolution profile with theoretical profile (similarity factor, f2 = 70.91). The dissolution of batch F7 can be described by zero-order kinetics (R2 =0.9936) with anomalous (non-Fickian) diffusion as the release mechanism (n=0.545). There was no difference observed in release profile after temperature sensitivity study at 40°C/75% relative humidity (RH) for 1 month. Conclusion: It can be concluded from this study that the combined mix matrix system containing hydrophobic and hydrophilic polymer minimized the burst release of drug from the tablet and achieved a drug release by zero

  5. Probabilistic Evaluation of Advanced Ceramic Matrix Composite Structures

    NASA Technical Reports Server (NTRS)

    Abumeri, Galib H.; Chamis, Christos C.

    2003-01-01

    The objective of this report is to summarize the deterministic and probabilistic structural evaluation results of two structures made with advanced ceramic composites (CMC): internally pressurized tube and uniformly loaded flange. The deterministic structural evaluation includes stress, displacement, and buckling analyses. It is carried out using the finite element code MHOST, developed for the 3-D inelastic analysis of structures that are made with advanced materials. The probabilistic evaluation is performed using the integrated probabilistic assessment of composite structures computer code IPACS. The affects of uncertainties in primitive variables related to the material, fabrication process, and loadings on the material property and structural response behavior are quantified. The primitive variables considered are: thermo-mechanical properties of fiber and matrix, fiber and void volume ratios, use temperature, and pressure. The probabilistic structural analysis and probabilistic strength results are used by IPACS to perform reliability and risk evaluation of the two structures. The results will show that the sensitivity information obtained for the two composite structures from the computational simulation can be used to alter the design process to meet desired service requirements. In addition to detailed probabilistic analysis of the two structures, the following were performed specifically on the CMC tube: (1) predicted the failure load and the buckling load, (2) performed coupled non-deterministic multi-disciplinary structural analysis, and (3) demonstrated that probabilistic sensitivities can be used to select a reduced set of design variables for optimization.

  6. Nondestructive Damage Evaluation in Ceramic Matrix Composites for Aerospace Applications

    PubMed Central

    Dassios, Konstantinos G.; Kordatos, Evangelos Z.; Aggelis, Dimitrios G.; Matikas, Theodore E.

    2013-01-01

    Infrared thermography (IRT) and acoustic emission (AE) are the two major nondestructive methodologies for evaluating damage in ceramic matrix composites (CMCs) for aerospace applications. The two techniques are applied herein to assess and monitor damage formation and evolution in a SiC-fiber reinforced CMC loaded under cyclic and fatigue loading. The paper explains how IRT and AE can be used for the assessment of the material's performance under fatigue. IRT and AE parameters are specifically used for the characterization of the complex damage mechanisms that occur during CMC fracture, and they enable the identification of the micromechanical processes that control material failure, mainly crack formation and propagation. Additionally, these nondestructive parameters help in early prediction of the residual life of the material and in establishing the fatigue limit of materials rapidly and accurately. PMID:23935428

  7. Nondestructive damage evaluation in ceramic matrix composites for aerospace applications.

    PubMed

    Dassios, Konstantinos G; Kordatos, Evangelos Z; Aggelis, Dimitrios G; Matikas, Theodore E

    2013-01-01

    Infrared thermography (IRT) and acoustic emission (AE) are the two major nondestructive methodologies for evaluating damage in ceramic matrix composites (CMCs) for aerospace applications. The two techniques are applied herein to assess and monitor damage formation and evolution in a SiC-fiber reinforced CMC loaded under cyclic and fatigue loading. The paper explains how IRT and AE can be used for the assessment of the material's performance under fatigue. IRT and AE parameters are specifically used for the characterization of the complex damage mechanisms that occur during CMC fracture, and they enable the identification of the micromechanical processes that control material failure, mainly crack formation and propagation. Additionally, these nondestructive parameters help in early prediction of the residual life of the material and in establishing the fatigue limit of materials rapidly and accurately.

  8. Probabilistic Evaluation of Bolted Joints in Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Minnetyan, L.

    1997-01-01

    Computational methods are described to probabilistically simulate fracture in bolted composite structures. Progressive fracture is simulated via an innovative approach independent of stress intensity factors and fracture toughness. The effect on structure damage of design variable uncertainties is quantified. The Fast Probability Integrator is used to assess the scatter in the composite structure response before and after damage. Sensitivity of the response to design variables is evaluated. The methods are demonstrated for bolted joint polymer matrix composite panels under end loads. The effects of fabrication process are included in the simulation of damage in the bolted panel. The results show that the most effective way to reduce the end displacement at fracture is to control the load and ply thickness.

  9. Readability evaluation of an active matrix electrophoric ink display

    NASA Astrophysics Data System (ADS)

    Meyer, Frederick M.; Trissell, Terry L.; Aleva, Denise L.; Longo, Sam J.; Hopper, Darrel G.

    2006-05-01

    A low-power, yet sunlight readable, display is needed for dismounted applications where the user must carry the power source. Such a display could potentially replace paper checklists and maps with electronic counterparts. A reflective active matrix electrophoretic ink display (AMEPID) was evaluated as a candidate technology for such applications. This display technology uses ambient illumination, rather than competing with it, and requires power only when rewriting the display. The device was tested for viewability under a variety of lighting conditions. Readability of displayed text, as compared to standard print on white paper, was evaluated in an indoor office environment and in outdoor lighting conditions. Viewability of the display with night vision goggles (NVGs) was evaluated under simulated full moon, starlight, and overcast illumination conditions. Objective measurements of luminance, contrast ratio and reflectance were conducted under corresponding irradiance conditions and viewing angles using state-of-the-art photometric and radiometric measurement equipment. In addition to visible spectrum measurements, infrared (IR) reflectance and contrast were measured for the extended spectrum of 720-1700 nm. Results are discussed in terms of performance criteria for military displays, which are often much more demanding than for civil applications.

  10. PHARMACODYNAMICAL EVALUATION OF MATRIX TYPE TRANSDERMAL THERAPEUTIC SYSTEMS CONTAINING CAPTOPRIL.

    PubMed

    Kerımoğlu, Oya; Şahbaz, Sevınç; Şehırlı, Özer; Ozdemır, Zarıfe Nıgar; Çetınel, Şule; Dortunç, Betül; Şener, Göksel

    2015-01-01

    The objective of this study was to evaluate pharmacodynamical properties of transdermal therapeutic systems (TTS) containing captopril together with synthetic and pH independent polymers, Eudragit RL 100 and RS 100. Optimum formulation was chosen according to the results of our previous study regarding in vitro dissolution and ex vivo diffusion rate studies through excised human skin by using Franz Diffusion Cell. Control group, hypertension group (HT) and TTS containing captopril hypertension group (HT-CAP) were assessed for the pharmacodynamic activity of the study. Pharmacodynamic activity of transdermal patches containing captopril was evaluated in rats by the measurement of systolic blood pressure for 24 h with the use of the tail cuff method. Blood pressure, heart rate, body and heart weight, heart and body weight ratio were determined. Lactate dehydrogenase (LDH), creatinine phosphokinase (CPK), glutathione (GSH), malondialdehyde (MDA), myeloperoxidase (MPO) and Na+, K(+)-ATPase were measured in the serum of rats. Histopathological evaluation of the heart tissue was conducted in order to determine any tissue damage. Blood pressure values of the TTS containing captopril hypertension group were decreased significantly and became almost similar with the blood pressure values of the control group. These results indicated that matrix type transdermal patches prepared with Eudragit RL 100 and RS 100 polymers containing captopril can be considered as transdermal therapeutic systems for chronical treatment of hypertension and congestive heart failure. However, further in vivo pharmacokinetic studies should be performed in order to determine the blood level of the drug.

  11. Revisiting the comparison between the Shack-Hartmann and the pyramid wavefront sensors via the Fisher information matrix.

    PubMed

    Plantet, C; Meimon, S; Conan, J-M; Fusco, T

    2015-11-02

    Exoplanet direct imaging with large ground based telescopes requires eXtreme Adaptive Optics that couples high-order adaptive optics and coronagraphy. A key element of such systems is the high-order wavefront sensor. We study here several high-order wavefront sensing approaches, and more precisely compare their sensitivity to noise. Three techniques are considered: the classical Shack-Hartmann sensor, the pyramid sensor and the recently proposed LIFTed Shack-Hartmann sensor. They are compared in a unified framework based on precise diffractive models and on the Fisher information matrix, which conveys the information present in the data whatever the estimation method. The diagonal elements of the inverse of the Fisher information matrix, which we use as a figure of merit, are similar to noise propagation coefficients. With these diagonal elements, so called "Fisher coefficients", we show that the LIFTed Shack-Hartmann and pyramid sensors outperform the classical Shack-Hartmann sensor. In photon noise regime, the LIFTed Shack-Hartmann and modulated pyramid sensors obtain a similar overall noise propagation. The LIFTed Shack-Hartmann sensor however provides attractive noise properties on high orders.

  12. EVALUATION OF THE EXTRACELLULAR MATRIX OF INJURED SUPRASPINATUS IN RATS

    PubMed Central

    Almeida, Luiz Henrique Oliveira; Ikemoto, Roberto; Mader, Ana Maria; Pinhal, Maria Aparecida Silva; Munhoz, Bruna; Murachovsky, Joel

    2016-01-01

    ABSTRACT Objective: To evaluate the evolution of injuries of the supraspinatus muscle by immunohistochemistry (IHC) and anatomopathological analysis in animal model (Wistar rats). Methods: Twenty-five Wistar rats were submitted to complete injury of the supraspinatus tendon, then subsequently sacrificed in groups of five animals at the following periods: immediately after the injury, 24h after the injury, 48h after, 30 days after and three months after the injury. All groups underwent histological and IHC analysis. Results: Regarding vascular proliferation and inflammatory infiltrate, we found a statistically significant difference between groups 1(control group) and 2 (24h after injury). IHC analysis showed that expression of vascular endothelial growth factor (VEGF) showed a statistically significant difference between groups 1 and 2, and collagen type 1 (Col-1) evaluation presented a statistically significant difference between groups 1 and 4. Conclusion: We observed changes in the extracellular matrix components compatible with remodeling and healing. Remodeling is more intense 24h after injury. However, VEGF and Col-1 are substantially increased at 24h and 30 days after the injury, respectively. Level of Evidence I, Experimental Study. PMID:26997907

  13. Fabrication and Preliminary Evaluation of Metal Matrix Microencapsulated Fuels

    SciTech Connect

    Terrani, Kurt A; Kiggans, Jim; Snead, Lance Lewis

    2012-01-01

    The metal matrix microencapsulated (M3) fuel concept for light water reactors (LWRs), consisting of coated fuel particles dispersed in a zirconium metal matrix, is introduced. Fabrication of M3 fuels by hot pressing, hot isostatic pressing, or extrusion methodologies has been demonstrated over the temperature range 800-1050 C. Various types of coated fuel particles with outermost layers of pyrocarbon, SiC, ZrC, and TiN have been incorporated into the zirconium metal matrix. Mechanical particle-particle and chemical particle-matrix interactions have been observed during the preliminary characterization of as-fabricated M3 specimens. Irradiation of three M3 rodlets with surrogate coated fuel particles was carried out at mean rod temperature of 400 C to 4.6 dpa in the zirconium metal matrix. Due to absence of texture in the metal matrix no irradiation growth strain (<0.09%) was detected during the post-irradiation examination.

  14. Exploration matrix evaluation of sedimentary basins of Colombia

    SciTech Connect

    Kanes, W.H.; Bueno, R.

    1989-03-01

    The sedimentary basins of Colombia are evaluated for the following five exploration criteria: (1) source rock potential, including total organic carbon, Rock-Eval analysis, and kerogen types; (2) seals, with specific units and lithologies designated in each basin; (3) reservoirs characteristics, with stress laid on porosity and permeability fairways developed in the various types of clastic depositional systems; (4) traps, whether structural or stratigraphic, and the most probable routes of hydrocarbon migration; and (5) timing, which also examines the interrelationship between maturation and expulsion of hydrocarbon and the formation of the structural or stratigraphic trap and seal. The exploration matrix is based on delineating the play concepts (up to five) for each sedimentary basin. These play concepts are based on a linear scale based on the probability of future or potential discoveries. All data for the analyses were provided by Ecopetrol and were subjectively weighed only where the number of wells in the basin was low in contrast to the basin area (<1:100 km/sup 2/) and there was no history of production.

  15. Cosmogenic 3He production rates revisited from evidences of grain size dependent release of matrix-sited helium

    USGS Publications Warehouse

    Blard, P.-H.; Pik, R.; Lave, J.; Bourles, D.; Burnard, P.G.; Yokochi, R.; Marty, B.; Trusdell, F.

    2006-01-01

    Measurements of the cosmogenic 3He (3Hec) content of various size aliquots of exposed olivines show that the fine fraction (<140 μm) has 3Hec concentrations between 14 and 100% lower than that of the coarse fractions (0.14–1 mm). Such differences attest to a grain size dependent partial release of 3Hec from the phenocrysts matrix during the preliminary in vacuo crushing. This result might have important implications since most 3Hec measurements have used for ∼20 yr a standard routine based on the fusion of bulk powdered phenocrysts, whatever their grain size. A suite of new data obtained from coarse olivine grains yielded a mean Sea Level High Latitude 3Hec production rate (SLHL P3) of 128±5 and 136±6 at. g−1 yr−1, depending on the scaling factors used. This new value, which is ∼15% higher than previously published rates, is obtained from 5 ropy flow surfaces of Mt Etna (38°N) and Hawaiian (19°N) volcanoes, at elevations between sea level and 870 m and ranging in age from 1.47±0.05 to 149±23 ka according to independent 14C or K/Ar dating. 3He loss during the crushing step might account for the discrepancy between the standard reference value of 110–115 at. g−1 y−1 and the higher SLHL P3 proposed here. More generally, removal of the powdered fraction before fusion is an important point to consider in further studies in order to avoid any 3Hec systematic underestimates.An altitudinal section has also been sampled on the ropy surface of a ∼1500 yr single flow of Mauna Loa (19°N) which allowed a new empirical atmospheric attenuation length of 149±22 g cm−2 to be documented for 3Hec in olivines between 2400 and 4000 m elevations.

  16. MATRIX PHOTOCATALYTIC, INC. PHOTOCATALYTIC OXIDATION TECHNOLOGY - INNOVATIVE TECHNOLOGY EVALUATION REPORT

    EPA Science Inventory

    The Matrix Technology involves the exposure of titanium dioxide (Ti02) particles to ultraviolet light (UV). The Ti02 is activated by UV light to produce high oxidizing hydroxyl radicals. Maxtrix also uses hydrogen peroxide (H202) and ozone (03) to enhance the treatment systems p...

  17. Design, installation, and performance evaluation of a custom dye matrix standard for automated capillary electrophoresis.

    PubMed

    Cloete, Kevin Wesley; Ristow, Peter Gustav; Kasu, Mohaimin; D'Amato, Maria Eugenia

    2017-03-01

    CE equipment detects and deconvolutes mixtures containing up to six fluorescently labeled DNA fragments. This deconvolution is done by the collection software that requires a spectral calibration file. The calibration file is used to adjust for the overlap that occurs between the emission spectra of fluorescence dyes. All commercial genotyping and sequencing kits require the installation of a corresponding matrix standard to generate a calibration file. Due to the differences in emission spectrum overlap between fluorescent dyes, the application of existing commercial matrix standards to the electrophoretic separation of DNA labeled with other fluorescent dyes can yield undesirable results. Currently, the number of fluorescent dyes available for oligonucleotide labeling surpasses the availability of commercial matrix standards. Therefore, in this study we developed and evaluated a customized matrix standard using ATTO 633, ATTO 565, ATTO 550, ATTO Rho6G, and 6-FAM dyes for which no commercial matrix standard is available. We highlighted the potential genotyping errors of using an incorrect matrix standard by evaluating the relative performance of our custom dye set using six matrix standards. The specific performance of two genotyping kits (UniQTyper™ Y-10 version 1.0 and PowerPlex® Y23 System) was also evaluated using their specific matrix standards. The procedure we followed for the construction of our custom dye matrix standard can be extended to other fluorescent dyes.

  18. [Electron transfer between globular proteins. Evaluation of a matrix element].

    PubMed

    Lakhno, V D; Chuev, G N; Ustinin, M N

    1998-01-01

    The dependence of the matrix element of the probability of interprotein electron transfer on the mutual orientation of the donor and acceptor centers and the distance between them was calculated. The calculations were made under the assumption that electron transfer proceeds mainly by a collective excitation of polaron nature, like a solvated electron state. The results obtained are consistent with experimental data and indicate the nonexponential behavior of this dependence in the case when the distance transfer is less than 20 A.

  19. SEM evaluation of nanoparticulate silver penetration into dentine collagen matrix

    NASA Astrophysics Data System (ADS)

    Bessudnova, Nadezda O.; Bilenko, David I.; Venig, Sergey B.

    2014-01-01

    In the present study a novel approach to caries management based on the application of nanoparticles of different nature to increase the mineral phase of demineralized dentin has been developed. Silver nanoparticles have been tested as a material for dentine matrix infiltration. Research findings clearly show that collagen fibers of demineralized dentine could be considered as a scaffold for mineral component delivery and the place where mineral growth can occur.

  20. Algebraic evaluation of matrix elements in the Laguerre function basis

    NASA Astrophysics Data System (ADS)

    McCoy, A. E.; Caprio, M. A.

    2016-02-01

    The Laguerre functions constitute one of the fundamental basis sets for calculations in atomic and molecular electron-structure theory, with applications in hadronic and nuclear theory as well. While similar in form to the Coulomb bound-state eigenfunctions (from the Schrödinger eigenproblem) or the Coulomb-Sturmian functions (from a related Sturm-Liouville problem), the Laguerre functions, unlike these former functions, constitute a complete, discrete, orthonormal set for square-integrable functions in three dimensions. We construct the SU(1, 1) × SO(3) dynamical algebra for the Laguerre functions and apply the ideas of factorization (or supersymmetric quantum mechanics) to derive shift operators for these functions. We use the resulting algebraic framework to derive analytic expressions for matrix elements of several basic radial operators (involving powers of the radial coordinate and radial derivative) in the Laguerre function basis. We illustrate how matrix elements for more general spherical tensor operators in three dimensional space, such as the gradient, may then be constructed from these radial matrix elements.

  1. Covariance Matrix Evaluations for Independent Mass Fission Yields

    SciTech Connect

    Terranova, N.; Serot, O.; Archier, P.; De Saint Jean, C.

    2015-01-15

    Recent needs for more accurate fission product yields include covariance information to allow improved uncertainty estimations of the parameters used by design codes. The aim of this work is to investigate the possibility to generate more reliable and complete uncertainty information on independent mass fission yields. Mass yields covariances are estimated through a convolution between the multi-Gaussian empirical model based on Brosa's fission modes, which describe the pre-neutron mass yields, and the average prompt neutron multiplicity curve. The covariance generation task has been approached using the Bayesian generalized least squared method through the CONRAD code. Preliminary results on mass yields variance-covariance matrix will be presented and discussed from physical grounds in the case of {sup 235}U(n{sub th}, f) and {sup 239}Pu(n{sub th}, f) reactions.

  2. Nondestructive evaluation of a ceramic matrix composite material

    NASA Technical Reports Server (NTRS)

    Grosskopf, Paul P.; Duke, John C., Jr.

    1992-01-01

    Monolithic ceramic materials have proven their usefulness in many applications, yet, their potential for critical structural applications is limited because of their sensitivity to small imperfections. To overcome this extreme sensitivity to small imperfections, ceramic matrix composite materials have been developed that have the ability to withstand some distributed damage. A borosilicate glass reinforced with several layers of silicon-carbide fiber mat has been studied. Four-point flexure and tension tests were performed not only to determine some of the material properties, but also to initiate a controlled amount of damage within each specimen. Acousto-ultrasonic (AU) measurements were performed periodically during mechanical testing. This paper will compare the AU results to the mechanical test results and data from other nondestructive methods including acoustic emission monitoring and X-ray radiography. It was found that the AU measurements were sensitive to the damage that had developed within the material.

  3. A space efficient flexible pivot selection approach to evaluate determinant and inverse of a matrix.

    PubMed

    Jafree, Hafsa Athar; Imtiaz, Muhammad; Inayatullah, Syed; Khan, Fozia Hanif; Nizami, Tajuddin

    2014-01-01

    This paper presents new simple approaches for evaluating determinant and inverse of a matrix. The choice of pivot selection has been kept arbitrary thus they reduce the error while solving an ill conditioned system. Computation of determinant of a matrix has been made more efficient by saving unnecessary data storage and also by reducing the order of the matrix at each iteration, while dictionary notation [1] has been incorporated for computing the matrix inverse thereby saving unnecessary calculations. These algorithms are highly class room oriented, easy to use and implemented by students. By taking the advantage of flexibility in pivot selection, one may easily avoid development of the fractions by most. Unlike the matrix inversion method [2] and [3], the presented algorithms obviate the use of permutations and inverse permutations.

  4. Controlled release evaluation of bacterial fertilizer using polymer composites as matrix.

    PubMed

    Wu, Chin-San

    2008-11-24

    The use of polybutylene succinate (PBSU)/starch-type composite as biodegradable matrix material for the controlled release of bacterial fertilizer was evaluated. The composites were prepared by a melting-blending method and various methods/instruments were applied to characterize composites and PBSU. The mechanical properties of the PBSU/starch composite were worse than PBSU alone because the former had poor compatibility between starch and the polymer matrix. Much better dispersion and homogeneity were observed in the composite when PBSU was replaced by acrylic acid grafted PBSU (PBSU-g-AA), hence leading to better mechanical properties of PBSU-g-AA/starch. Furthermore, PBSU-g-AA/starch was more easily processed. The bacterial fertilizer was encapsulated in PBSU and PBSU-g-AA/starch matrix. Increased blending of starch increased the biodegradability of matrix and the amount and rate of cell release from matrix suggesting that this composite is a promising candidate material for 'controlled release' bacterial fertilizer.

  5. Evaluative Priming of Naming and Semantic Categorization Responses Revisited: A Mutual Facilitation Explanation

    ERIC Educational Resources Information Center

    Schmitz, Melanie; Wentura, Dirk

    2012-01-01

    The evaluative priming effect (i.e., faster target responses following evaluatively congruent compared with evaluatively incongruent primes) in nonevaluative priming tasks (such as naming or semantic categorization tasks) is considered important for the question of how evaluative connotations are represented in memory. However, the empirical…

  6. Uncertainty evaluation for the matrix ``solidified state'' of fissionable elements

    NASA Astrophysics Data System (ADS)

    Iliescu, Elena; Iancso, Georgeta

    2012-09-01

    In case of the analysis of the radioactive liquid samples, no matter the relative physical analysis method used, two impediments act that belong to the behavior in time of the dispersion state of the liquid samples to be analyzed and of the standard used in the analysis. That is, one of them refers to the state of the sample to be analyzed when being sampled, which "alter" during the time elapsed from sampling up to the analysis of the sample. The other impediment is the natural change of the dispersion state of the standard radioactive solutions, due to the occurrence and evolution in time of the radiocolloidal and pseudo-radiocolloidal states. These radiocolloidal states are states of aggregation and they lead to the destruction of the homogeneity of the solutions. Taking into consideration the advantages offered by the relative physical methods of analysis as against the chemical or the radiochemical ones, different ways of eliminating these impediments have been tried. We eliminated these impediments processing the liquid reference materials (the solutions calibrated in radionuclides of interest), immediately after the preparation. This processing changes the liquid physical state of the reference materials in a "solidified state". Through this procedure the dispersion states of the samples, practically, can no longer be essentially modified in time and also ensure the uniform distribution of the radionuclides of interest in the elemental matrix of the samples "state solidified". The homogeneity of the distribution of the atoms of the radionuclides from the samples "solidified state" was checked up through the track micromapping technique of the alpha particles. Through this technique, in the chemically etched track detectors that were put in direct contact with the sample for a determined period of time, the alpha exposure time of the detectors, micromaps of alpha tracks were obtained. These micromaps are retorts through tracks of the distributions atoms of

  7. Nondestructive evaluation of ceramic and metal matrix composites for NASA's HITEMP and enabling propulsion materials programs

    NASA Technical Reports Server (NTRS)

    Generazio, Edward R.

    1992-01-01

    In a preliminary study, ultrasonic, x-ray opaque, and fluorescent dye penetrants techniques were used to evaluate and characterize ceramic and metal matrix composites. Techniques are highlighted for identifying porosity, fiber alignment, fiber uniformity, matrix cracks, fiber fractures, unbonds or disbonds between laminae, and fiber-to-matrix bond variations. The nondestructive evaluations (NDE) were performed during processing and after thermomechanical testing. Specific examples are given for Si3N4/SiC (SCS-6 fiber), FeCrAlY/Al2O3 fibers, Ti-15-3/SiC (SCS-6 fiber) materials, and Si3N4/SiC (SCS-6 fiber) actively cooled panel components. Results of this study indicate that the choice of the NDE tools to be used can be optimized to yield a faithful and accurate evaluation of advanced composites.

  8. Characterization and Damage Evaluation of Coal Tar Pitch Carbon Matrix Used in Carbon/Carbon Composites

    NASA Astrophysics Data System (ADS)

    Bhagat, Atul Ramesh; Mahajan, Puneet

    2016-09-01

    Flexure, compressive, and shear properties of the carbon matrix in carbon/carbon (C/C) composites made via a pitch impregnation method have been determined. The pitch carbon matrix was made using the same densification cycle used in making the C/C composite. Cyclic compression tests were performed on the matrix specimens. While unloading, a reduction in modulus was observed and residual strains were observed on complete unloading. These features were attributed to the presence of damage and plasticity in the densified matrix. A J 2 plasticity model with damage was used to simulate this behavior numerically. The parameters required for plasticity and damage model were evaluated iteratively by comparing the results in experiments with simulation.

  9. Efficient and accurate evaluation of potential energy matrix elements for quantum dynamics using Gaussian process regression

    NASA Astrophysics Data System (ADS)

    Alborzpour, Jonathan P.; Tew, David P.; Habershon, Scott

    2016-11-01

    Solution of the time-dependent Schrödinger equation using a linear combination of basis functions, such as Gaussian wavepackets (GWPs), requires costly evaluation of integrals over the entire potential energy surface (PES) of the system. The standard approach, motivated by computational tractability for direct dynamics, is to approximate the PES with a second order Taylor expansion, for example centred at each GWP. In this article, we propose an alternative method for approximating PES matrix elements based on PES interpolation using Gaussian process regression (GPR). Our GPR scheme requires only single-point evaluations of the PES at a limited number of configurations in each time-step; the necessity of performing often-expensive evaluations of the Hessian matrix is completely avoided. In applications to 2-, 5-, and 10-dimensional benchmark models describing a tunnelling coordinate coupled non-linearly to a set of harmonic oscillators, we find that our GPR method results in PES matrix elements for which the average error is, in the best case, two orders-of-magnitude smaller and, in the worst case, directly comparable to that determined by any other Taylor expansion method, without requiring additional PES evaluations or Hessian matrices. Given the computational simplicity of GPR, as well as the opportunities for further refinement of the procedure highlighted herein, we argue that our GPR methodology should replace methods for evaluating PES matrix elements using Taylor expansions in quantum dynamics simulations.

  10. Revisiting the relation between contingency awareness and attention: evaluative conditioning relies on a contingency focus.

    PubMed

    Kattner, Florian

    2012-01-01

    Although evaluative conditioning has occasionally been demonstrated in the absence of contingency awareness, many recent studies imply that its acquisition depends on the availability of attentional resources during conditioning. In previous experiments attention has typically been manipulated in a general way rather than looking at the particular focus of attention. The present study investigated the role of a focus on the CS-US contingency. Two separate distraction tasks were designed that either diverted attention from the stimuli or directed it to the stimuli while drawing attention away from the contingency between the stimuli. Both types of distraction were shown to eliminate evaluative conditioning. Significant evaluative conditioning was observed in a third group of participants who were required to attend the contingencies. A mediation analysis showed that the observed discrepancy in evaluative conditioning effects between groups was mediated by contingency awareness. The results imply that attention in terms of a stimulus focus is not sufficient for evaluative conditioning to occur. Rather, attention to the contingencies between stimuli appears to be crucial in evaluative conditioning, because it is supposed to foster the acquisition of contingency awareness.

  11. The Components of Smile Design: New York University Smile Evaluation Form Revisited, Update 2015.

    PubMed

    Calamia, John R; Wolff, Mark S

    2015-07-01

    This article updates a simple checklist of foundational knowledge in aesthetic dental concepts that allows clinicians to organize their thoughts, to record the concerns of the patient, and to map out those improvements that must be addressed. This adjunct is called a Smile Evaluation Form. Along with other adjuncts such as radiographs, study casts, and diagnostic wax-ups, the Smile Evaluation Form allows clinicians to form a conceptual visualization of the expected end point. It provides a checklist for discussions with other disciplines in the team, to provide a logical sequence of treatment with a mutually agreed-on end point.

  12. The Data Collection Matrix Model: A Tool for Functional Area and Program Evaluation.

    ERIC Educational Resources Information Center

    Coker, Dana Rosenberg; Friedel, Janice Nahra

    1991-01-01

    The data collection matrix makes possible the integration of functional area data from numerous assessment sources and presentation of the information in a unified composite report. This model is discussed in relation to the various assessment instruments and the evaluation of functional areas and programs in colleges and universities. (Author/MSE)

  13. On Information Retrieval (IR) Systems: Revisiting Their Development, Evaluation Methodologies, and Assumptions (SIGs LAN, ED).

    ERIC Educational Resources Information Center

    Stirling, Keith

    2000-01-01

    Describes a session on information retrieval systems that planned to discuss relevance measures with Web-based information retrieval; retrieval system performance and evaluation; probabilistic independence of index terms; vector-based models; metalanguages and digital objects; how users assess the reliability, timeliness and bias of information;…

  14. Counterfactual Evaluation of Outcomes in Social Risk Decision-Making Situations: The Cognitive Developmental Paradox Revisited

    PubMed Central

    Padrón, Iván; Rodrigo, María Jose; de Vega, Manuel

    2016-01-01

    We report a study that examined the existence of a cognitive developmental paradox in the counterfactual evaluation of decision-making outcomes. According to this paradox adolescents and young adults could be able to apply counterfactual reasoning and, yet, their counterfactual evaluation of outcomes could be biased in a salient socio-emotional context. To this aim, we analyzed the impact of health and social feedback on the counterfactual evaluation of outcomes in a laboratory decision-making task involving short narratives with the presence of peers. Forty risky (e.g., taking or refusing a drug), forty neutral decisions (e.g., eating a hamburger or a hotdog), and emotions felt following positive or negative outcomes were examined in 256 early, mid- and late adolescents, and young adults, evenly distributed. Results showed that emotional ratings to negative outcomes (regret and disappointment) but not to positive outcomes (relief and elation) were attenuated when feedback was provided. Evidence of development of cognitive decision-making capacities did also exist, as the capacity to perform faster emotional ratings and to differentially allocate more resources to the elaboration of emotional ratings when no feedback information was available increased with age. Overall, we interpret these findings as challenging the traditional cognitive developmental assumption that development necessarily proceeds from lesser to greater capacities, reflecting the impact of socio-emotional processes that could bias the counterfactual evaluation of social decision-making outcomes. PMID:27152127

  15. Holland in Iceland revisited: an emic approach to evaluating U.S. vocational interest models.

    PubMed

    Einarsdóttir, Sif; Rounds, James; Su, Rong

    2010-07-01

    An emic approach was used to test the structural validity and applicability of Holland's (1997) RIASEC (Realistic, Investigative, Artistic, Social, Enterprising, Conventional) model in Iceland. Archival data from the development of the Icelandic Interest Inventory (Einarsdóttir & Rounds, 2007) were used in the present investigation. The data included an indigenous pool of occupations and work-task items representing Iceland's world of work that had been administered to a sample of 597 upper secondary school students. Multidimensional scaling analysis and property vector fitting using Prediger's (1981) work-task dimensions were applied to the item responses to test if the RIASEC model could be identified. The results indicated that a 4-dimensional solution better explains the interest space in Iceland than Holland's 2-dimensional RIASEC representation. The work-task dimension of People-Things and the Sex-Type and Prestige dimensions were located in the 1st and 2nd dimensions of the multidimensional scaling solution, but Data-Ideas, a dimension critical to the RIASEC model, was not. The 3rd and 4th dimensions did not correspond to any dimensions previously detected in structural studies in the United States and seem to be related to specific ecological, cultural, and political forces in Iceland. These results demonstrate the importance of selecting representative indigenous occupations and work tasks when evaluating the RIASEC model. The present study is an example of the next step in a comprehensive cross-cultural research program on vocational interests, an emic investigation.

  16. Formation of HArF in solid Ar revisited: are mobile vacancies involved in the matrix-site conversion at 30 K?

    PubMed

    Khriachtchev, Leonid; Lignell, Antti; Rasanen, Markku

    2004-02-15

    The HArF molecule can occupy in solid Ar thermally unstable and stable configurations, and their microscopic structure is not understood at the moment. We present additional experimental results on the formation of two HArF configurations and analyze them with emphasis on possible reactions of the unstable configuration with matrix vacancies to form the stable configuration. We conclude that the existing computational scenarios do not describe fully the present experimental data. In order to explain qualitatively the experimental results, two tentative models are discussed. The first model is based on local mobility of matrix vacancies produced during photolysis and the second model considers isomerization of the HArF at Arn supermolecule. More importantly, the present results constitute the experimental basis for future theoretical studies.

  17. Evaluation of microwave digestion systems for mercury recovery in an oil matrix

    SciTech Connect

    Whitaker, M.J.; Clymire, J.W.

    1997-09-01

    The scope of this document is to characterize three microwave systems developed by CEM Corporation. The purpose of this investigative work was to evaluate the performance of each system for dissolution qualities and the recovery of mercury in an oil based matrix. The microwave systems evaluated were the heavy duty vessel system (HDV), the advanced composite system (ACV), and the open vessel system (OVS). All three systems have automated features, but all systems are limited by one factor or another. EPA method 3051 was the procedure used for sample preparation for this project. This particular microwave digestion method can also be used for other metal analytes of interest. Of the three different systems, only the HDV (now UDV) demonstrated complete digestion of the oil based matrix in a one step process and acceptable mercury recoveries.

  18. (239)Pu neutron resonance parameters revisited and covariance matrix in the neutron energy range from thermal to 2.5 keV

    SciTech Connect

    Derrien, Herve; Leal, Luiz C; Larson, Nancy M

    2008-01-01

    To obtain the resonance parameters in a single energy range up to 2.5 keV neutron energy and the corresponding covariance matrix, a reevaluation of 239Pu was performed with the analysis code SAMMY. The most recent experimental data were analyzed in the energy range thermal to 2.5 keV. The experimental data were renormalized, aligned on a common energy scale, and corrected for residual background. Average neutron transmission and cross sections calculated with the new resonance parameters were compared to the corresponding experimental data and to ENDF/B-VI.

  19. Evaluation of a gelatin matrix as a topical hemostatic agent for hepatic bleeding in the dog.

    PubMed

    Polidoro, Daniel P; Kass, Philip H

    2013-01-01

    New generation topical hemostatic agents containing thrombin have been developed for use in surgical procedures when control of bleeding by conventional methods is either ineffective or impractical. The authors compared the safety, hemostatic efficacy, and handling characteristics of a thrombin-containing topical surgical hemostatic agent (a gelatin matrix) to a hemostatic gelatin sponge for treatment of parenchymal bleeding after liver biopsy. Fourteen dogs were enrolled in this prospective clinical study. Paired 1.5 cm × 1.5 cm and 0.5 cm deep liver biopsies were obtained via laparotomy for each dog. One bleeding liver biopsy lesion was treated with the gelatin matrix and the other with a gelatin sponge. The treated liver biopsy sites were compared for bleeding severity, time to hemostasis, cumulative blood loss, and hemostatic agent handling characteristics. Median time to hemostasis was significantly shorter (P = 0.034) and median cumulative blood loss was significantly lower (P = 0.033) for the lesions treated with the gelatin matrix than the gelatin sponge. Adverse reactions were not observed within the first 24 hr postoperatively. When used to control parenchymal bleeding from liver biopsy sites in the dog, the evaluated gelatin matrix was safe and more effective than the gelatin sponge.

  20. A design and evaluation of layered matrix tablet formulations of metoprolol tartrate.

    PubMed

    Baloğlu, Esra; Senyiğit, Taner

    2010-06-01

    The aim of this paper was to evaluate the performance of different swellable polymers in the form of layered matrix tablets to provide controlled therapeutic effect of metoprolol tartrate for twice daily administration. Seven different swellable polymers (carrageenan, hydroxypropylmethyl cellulose, pectin, guar gum, xanthan gum, chitosan, and ethyl cellulose) were evaluated alone or in combination as release-retardant layer. Tablets were tested for weight variation, hardness, diameter/thickness ratio, friability, and drug content uniformity and subjected to in vitro drug-release studies. In addition, the target-release profile of metoprolol tartrate was plotted using its clinical pharmacokinetic data, and the release profiles of the tablets were evaluated in relation to the plotted target release profile. Carrageenan was determined as the best polymer in two-layered matrix tablet formulations due to its better accordance to the target release profile and was selected for preparing three-layered matrix tablets. Carrageenan formulations exhibited super case II release mechanism. Accelerated stability testing was performed on two- and three-layered matrix tablet formulations of carrageenan. The tablets were stored at 25 degrees C/60% relative humidity and 40 degrees C/75% relative humidity for 6 months and examined for physical appearance, drug content, and release characteristics. At the end of the storage time, formulations showed no change either in physical appearance, drug content, or drug-release profile. These results demonstrated the suitability of three-layered tablet formulation of carrageenan to provide controlled release and improved linearity for metoprolol tartrate in comparison to two-layered tablet formulation.

  1. Evaluation of injection moulding as a pharmaceutical technology to produce matrix tablets.

    PubMed

    Quinten, Thomas; De Beer, Thomas; Vervaet, Chris; Remon, Jean Paul

    2009-01-01

    The aim of this study was to develop sustained-release matrix tablets by means of injection moulding and to evaluate the influence of process temperature, matrix composition (EC and HPMC concentration) and viscosity grade of ethylcellulose (EC) and hydroxypropylmethylcellulose (HPMC) on processability and drug release. The drug release data were analyzed to get insight in the release kinetics and mechanism. Formulations containing metoprolol tartrate (30%, model drug), EC with dibutyl sebacate (matrix former and plasticizer) and hydrophilic polymer HPMC were extruded and subsequently injection moulded into tablets (375 mg, 10 mm diameter, convex-shaped) at temperatures ranging from 110 to 140 degrees C. Tablets containing 30% metoprolol and 70% ethylcellulose (EC 4mPa s) showed an incomplete drug release within 24 h (<50%). Increasing production temperatures resulted in a lower drug release rate. Substituting part of the EC fraction by HPMC (HPMC/EC-ratio: 20/50 and 35/35) resulted in faster and constant drug release rates. Formulations containing 50% HPMC had a complete and first-order drug release profile with drug release controlled via the combination of diffusion and swelling/erosion. Faster drug release rates were observed for higher viscosity grades of EC (Mw>20 mPa s) and HPMC (4000 and 10,000 mPa s). Tablet porosity was low (<4%). Differential scanning calorimetry (DSC) and X-ray powder diffraction studies (X-RD) showed that solid dispersions were formed during processing. Using thermogravimetrical analysis (TGA) and gel-permeation chromatography no degradation of drug and matrix polymer was observed. The surface morphology was investigated with the aid of scanning electron microscopy (SEM) showing an influence of the process temperature. Raman spectroscopy demonstrated that the drug is distributed in the entire matrix, however, some drug clusters were identified.

  2. Laboratory Experiments to Evaluate Diffusion of 14C into Nevada Test Site Carbonate Aquifer Matrix

    SciTech Connect

    Ronald L. Hershey; William Howcroft; Paul W. Reimus

    2003-03-01

    Determination of groundwater flow velocities at the Nevada Test Site is important since groundwater is the principal transport medium of underground radionuclides. However, 14C-based groundwater velocities in the carbonate aquifers of the Nevada Test Site are several orders of magnitude slower than velocities derived from the Underground Test Area regional numerical model. This discrepancy has been attributed to the loss or retardation of 14C from groundwater into the surrounding aquifer matrix making 14C-based groundwater ages appear much older. Laboratory experiments were used to investigate the retardation of 14C in the carbonate aquifers at the Nevada Test Site. Three sets of experiments were conducted evaluating the diffusion of 14C into the carbonate aquifer matrix, adsorption and/or isotopic exchange onto the pore surfaces of the carbonate matrix, and adsorption and/or isotopic exchange onto the fracture surfaces of the carbonate aquifer. Experimental results a nd published aquifer matrix and fracture porosities from the Lower Carbonate Aquifer were applied to a 14C retardation model. The model produced an extremely wide range of retardation factors because of the wide range of published aquifer matrix and fracture porosities (over three orders of magnitude). Large retardation factors suggest that groundwater with very little measured 14C activity may actually be very young if matrix porosity is large relative to the fracture porosity. Groundwater samples collected from highly fractured aquifers with large effective fracture porosities may have relatively small correction factors, while samples from aquifers with a few widely spaced fractures may have very large correction factors. These retardation factors were then used to calculate groundwater velocities from a proposed flow path at the Nevada Test Site. The upper end of the range of 14C correction factors estimated groundwater velocities that appear to be at least an order of magnitude too high compared

  3. Evaluation of tensile strength of hybrid fiber (jute/gongura) reinforced hybrid polymer matrix composites

    NASA Astrophysics Data System (ADS)

    Venkatachalam, G.; Gautham Shankar, A.; Vijay, Kumar V.; Chandan, Byral R.; Prabaharan, G. P.; Raghav, Dasarath

    2015-07-01

    The polymer matrix composites attract many industrial applications due to its light weight, less cost and easy for manufacturing. In this paper, an attempt is made to prepare and study of the tensile strength of hybrid (two natural) fibers reinforced hybrid (Natural + Synthetic) polymer matrix composites. The samples were prepared with hybrid reinforcement consists of two different fibers such as jute and Gongura and hybrid polymer consists of polyester and cashew nut shell resins. The hybrid composites tensile strength is evaluated to study the influence of various fiber parameters on mechanical strength. The parameters considered here are the duration of fiber treatment, the concentration of alkali in fiber treatment and nature of fiber content in the composites.

  4. Analytic evaluation of the dipole Hessian matrix in coupled-cluster theory

    NASA Astrophysics Data System (ADS)

    Jagau, Thomas-C.; Gauss, Jürgen; Ruud, Kenneth

    2013-10-01

    The general theory required for the calculation of analytic third energy derivatives at the coupled-cluster level of theory is presented and connected to preceding special formulations for hyperpolarizabilities and polarizability gradients. Based on our theory, we have implemented a scheme for calculating the dipole Hessian matrix in a fully analytical manner within the coupled-cluster singles and doubles approximation. The dipole Hessian matrix is the second geometrical derivative of the dipole moment and thus a third derivative of the energy. It plays a crucial role in IR spectroscopy when taking into account anharmonic effects and is also essential for computing vibrational corrections to dipole moments. The superior accuracy of the analytic evaluation of third energy derivatives as compared to numerical differentiation schemes is demonstrated in some pilot calculations.

  5. Evaluation of Solid Modeling Software for Finite Element Analysis of Woven Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Nemeth, Noel N.; Mital, Subodh; Lang, Jerry

    2010-01-01

    Three computer programs, used for the purpose of generating 3-D finite element models of the Repeating Unit Cell (RUC) of a textile, were examined for suitability to model woven Ceramic Matrix Composites (CMCs). The programs evaluated were the open-source available TexGen, the commercially available WiseTex, and the proprietary Composite Material Evaluator (COMATE). A five-harness-satin (5HS) weave for a melt-infiltrated (MI) silicon carbide matrix and silicon carbide fiber was selected as an example problem and the programs were tested for their ability to generate a finite element model of the RUC. The programs were also evaluated for ease-of-use and capability, particularly for the capability to introduce various defect types such as porosity, ply shifting, and nesting of a laminate. Overall, it was found that TexGen and WiseTex were useful for generating solid models of the tow geometry; however, there was a lack of consistency in generating well-conditioned finite element meshes of the tows and matrix. TexGen and WiseTex were both capable of allowing collective and individual shifting of tows within a ply and WiseTex also had a ply nesting capability. TexGen and WiseTex were sufficiently userfriendly and both included a Graphical User Interface (GUI). COMATE was satisfactory in generating a 5HS finite element mesh of an idealized weave geometry but COMATE lacked a GUI and was limited to only 5HS and 8HS weaves compared to the larger amount of weave selections available with TexGen and WiseTex.

  6. Evaluation of a Variable-Impedance Ceramic Matrix Composite Acoustic Liner

    NASA Technical Reports Server (NTRS)

    Jones, M. G.; Watson, W. R.; Nark, D. M.; Howerton, B. M.

    2014-01-01

    As a result of significant progress in the reduction of fan and jet noise, there is growing concern regarding core noise. One method for achieving core noise reduction is via the use of acoustic liners. However, these liners must be constructed with materials suitable for high temperature environments and should be designed for optimum absorption of the broadband core noise spectrum. This paper presents results of tests conducted in the NASA Langley Liner Technology Facility to evaluate a variable-impedance ceramic matrix composite acoustic liner that offers the potential to achieve each of these goals. One concern is the porosity of the ceramic matrix composite material, and whether this might affect the predictability of liners constructed with this material. Comparisons between two variable-depth liners, one constructed with ceramic matrix composite material and the other constructed via stereolithography, are used to demonstrate this material porosity is not a concern. Also, some interesting observations are noted regarding the orientation of variable-depth liners. Finally, two propagation codes are validated via comparisons of predicted and measured acoustic pressure profiles for a variable-depth liner.

  7. Method and apparatus for evaluating structural weakness in polymer matrix composites

    DOEpatents

    Wachter, E.A.; Fisher, W.G.

    1996-01-09

    A method and apparatus for evaluating structural weaknesses in polymer matrix composites is described. An object to be studied is illuminated with laser radiation and fluorescence emanating therefrom is collected and filtered. The fluorescence is then imaged and the image is studied to determine fluorescence intensity over the surface of the object being studied and the wavelength of maximum fluorescent intensity. Such images provide a map of the structural integrity of the part being studied and weaknesses, particularly weaknesses created by exposure of the object to heat, are readily visible in the image. 6 figs.

  8. Method and apparatus for evaluating structural weakness in polymer matrix composites

    DOEpatents

    Wachter, Eric A.; Fisher, Walter G.

    1996-01-01

    A method and apparatus for evaluating structural weaknesses in polymer matrix composites is described. An object to be studied is illuminated with laser radiation and fluorescence emanating therefrom is collected and filtered. The fluorescence is then imaged and the image is studied to determine fluorescence intensity over the surface of the object being studied and the wavelength of maximum fluorescent intensity. Such images provide a map of the structural integrity of the part being studied and weaknesses, particularly weaknesses created by exposure of the object to heat, are readily visible in the image.

  9. Potential inert matrix materials: Materials synthesis and evaluation of in-service engineering parameters

    NASA Astrophysics Data System (ADS)

    Xu, Peng

    Containing no fertile materials, inert matrix fuel (IMF) has been introduced as a potential transmutation solution for the increasing inventory of both weapon grade and reactor grade plutonium (Pu). In the present work, the MgO-pyrochlore (Nd2Zr2O7) composites and spinel magnesium stannate (Mg2SnO4) were selected as potential inert matrix (IM) materials. A comprehensive investigation was conducted on evaluation of the engineering parameters of the potential IM materials. The MgO-Nd2Zr2O7 composites and Mg 2SnO4 were fabricated through conventional solid state processing. The crystal structure and microstructure of the synthesized composites and Mg2SnO4 were studied. The irradiation tolerance of the potential IM materials was first assessed. The resistance of Mg2SnO 4 against irradiation induced amorphization was assessed experimentally using in situ TEM technique. The critical amorphization doses for Mg2SnO4 irradiated by 1 MeV Kr2+ ions were determined to be 5.5 dpa at 50 K and 11.0 dpa at 150 K, respectively. The obtained results were compared with other spinels especially MgAl 2O4, and the radiation tolerance of spinels were discussed. The next evaluation was water corrosion resistance of the potential IM materials. Homogeneous MgO-Nd2Zr2O7 composites exhibited an improved hydrothermal corrosion resistance than inhomogeneous composites and pure MgO. Even though spinel Mg2SnO4 was not stable in water at 300°C and saturation pressure, the corrosion was limited only to the surface, and the volume and mass changes were less than 1 % after 720 h corrosion. Feasibility of aqueous reprocessing was evaluated by studying the dissolution behavior of the potential IM materials in acidic solutions, with an emphasis on nitric acid. Dissolution of the MgO-Nd2Zr2O 7 composites in HNO3 resulted in a selective dissolution of MgO. Mechanical agitation such as magnetic bar stirring was necessary to achieve a completed dissolution of MgO and disintegration of porous Nd 2Zr2O7

  10. An Evaluation of Matrix-Containing and Humanised Matrix-Free 3-Dimensional Cell Culture Systems for Studying Breast Cancer

    PubMed Central

    Roberts, Grace C.; Morris, Paul G.; Moss, Marcus A.; Maltby, Sarah L.; Palmer, Chelsea A.; Nash, Claire E.; Smart, Emily; Holliday, Deborah L.; Speirs, Valerie

    2016-01-01

    Background 3D cell cultures are emerging as more physiologically meaningful alternatives to monolayer cultures for many biological applications. They are attractive because they more closely mimic in vivo morphology, especially when co-cultured with stromal fibroblasts. Methodology/Principal Findings We compared the efficacy of 3 different 3D cell culture systems; collagen I, low attachment culture vessels and a modification of Fibrolife®, a specialised humanised cell culture medium devoid of animal-derived components, using breast cancer cell lines representative of the different molecular subtypes of breast cancer, cultured alone or with human mammary fibroblasts with a view to developing matrix-free humanised systems. 3D collagen I culture supported the growth of a range of breast cancer cell lines. By modifying the composition of Fibrolife® to epiFL, matrix-free cell culture was possible. During sequential transfer to epiFL breast cancer cells gradually detached from the flask, growing progressively as spheroids. Phenotype was stable and reversible with cells remaining actively proliferating and easily accessible throughout culture. They could also be revived from frozen stocks. To achieve co-culture with fibroblasts in epiFL required use of low attachment culture vessels instead of standard plastic as fibroblasts remained adherent in epiFL. Here, cancer cell spheroids were allowed to form before adding fibroblasts. Immunohistochemical examination showed fibroblasts scattered throughout the epithelial spheroid, not dissimilar to the relationship of tumour stroma in human breast cancer. Conclusions Because of its ease of handling, matrix-free 3D cell culture may be a useful model to study the influence of fibroblasts on breast cancer epithelial cells with use of epiFL culture medium taking this a step further towards a fully humanised 3D model. This methodology could be applied to other types of cancer cell lines, making this a versatile technique for cancer

  11. Evaluation of Concepts for Mulitiple Application Thermal Reactor for Irradiation eXperiments (MATRIX)

    SciTech Connect

    Michael A. Pope; Hans D. Gougar; John M. Ryskamp

    2013-09-01

    The Advanced Test Reactor (ATR) is a high power density test reactor specializing in fuel and materials irradiation. For more than 45 years, the ATR has provided irradiations of materials and fuels testing along with radioisotope production. Originally operated primarily in support of the Offcie of Naval Reactors (NR), the mission has gradually expanded to cater to other customers, such as the DOE Office of Nuclear Energy (NE), private industry, and universities. Unforeseen circumstances may lead to the decommissioning of ATR, thus leaving the U.S. Government without a large-scale materials irradiation capability to meet the needs of its nuclear energy and naval reactor missions. In anticipation of this possibility, work was performed under the Laboratory Directed Research and Development (LDRD) program to investigate test reactor concepts that could satisfy the current missions of the ATR along with an expanded set of secondary missions. This work can be viewed as an update to a project from the 1990’s called the Broad Application Test Reactor (BATR). In FY 2012, a survey of anticipated customer needs was performed, followed by analysis of the original BATR concepts with fuel changed to low-enriched uranium. Departing from these original BATR designs, four concepts were identified for further analysis in FY2013. The project informally adopted the acronym MATRIX (Multiple-Application Thermal Reactor for Irradiation eXperiments). This report discusses analysis of the four MATRIX concepts along with a number of variations on these main concepts. Designs were evaluated based on their satisfaction of anticipated customer requirements and the “Cylindrical” variant was selected for further analysis of options. This downselection should be considered preliminary and the backup alternatives should include the other three main designs. The baseline Cylindrical MATRIX design is expected to be capable of higher burnup than the ATR (or longer cycle length given a

  12. [Implementation of multi-strategy programs: a proposal for an evaluation matrix].

    PubMed

    Magalhães, Rosana

    2014-07-01

    The programs that seek to achieve comprehensive changes involve the relationship between different public policies, understanding the diversity of social demands in each context and enhancing a participative dynamic. Due to the complexity of these experiences, it is important to review the traditional perspectives and discuss alternatives. Based on the analytical framework of the so-called theory-driven evaluation, the core focus of which is the analysis of the validity of the concepts that link processes and results and the exploratory case study of the qualitative character of the federal Bolsa Familia cash transfer program, the paper proposes a methodological matrix as its main result to support the evaluation of interventions related to health promotion, food security and poverty reduction.

  13. Preliminary evaluation of adhesion strength measurement devices for ceramic/titanium matrix composite bonds

    NASA Technical Reports Server (NTRS)

    Pohlchuck, Bobby; Zeller, Mary V.

    1992-01-01

    The adhesive bond between ceramic cement and a titanium matrix composite substrate to be used in the National Aerospace Plane program is evaluated. Two commercially available adhesion testers, the Sebastian Adherence Tester and the CSEM REVETEST Scratch Tester, are evaluated to determine their suitability for quantitatively measuring adhesion strength. Various thicknesses of cements are applied to several substrates, and bond strengths are determined with both testers. The Sabastian Adherence Tester has provided limited data due to an interference from the sample mounting procedure, and has been shown to be incapable of distinguishing adhesion strength from tensile and shear properties of the cement itself. The data from the scratch tester has been found to be difficult to interpret due to the porosity and hardness of the cement. Recommendations are proposed for a more reliable adhesion test method.

  14. Formulation and evaluation of mucoadhesive matrix tablets of taro gum: optimization using response surface methodology.

    PubMed

    Arora, Gurpreet; Malik, Karan; Singh, Inderbir

    2011-01-01

    The present study was aimed to formulate and evaluate oral controlled release mucoadhesive matrix tablets of taro gum incorporating domperidone as model drug. Tablets were prepared by direct compression and were evaluated for bioadhesive strength and in vitro dissolution parameters. A central composite design for 2 factors, at 3 levels each, was employed to evaluate the effect of criti cal formulation variables, namely the amount of taro gum (X1) and PVP K 30 (X2), on mucoadhesive strength, tensile strength, release exponent (n) and t50 (time for 50% drug release). The mucoadhesive detachment force (evaluated using texture analyzer) was found to be 18.266, 54.684 and 65.904 N for A4, A5 and A6 batches of the formulated tablets. The polynomial equation indicates that taro gum has dominating effect on mucoadhesive strength and both X1 and X2 have almost equal and comparable effect on tensile strength. The drug release follows first order kinetics (release of drug depends on remaining concentration of drug) and shows best linearity (r2 = 0.983) with higuchi model. The release exponent (n) lies between 0.339 and 0.543 indicating drug release from the matrix tablets may be fickian or non fickian (anamolous) depending upon the concentration of natural polymer. T50 was 58, 140 and 220 minutes for A7, A8 and A9 batches showing overriding potential of taro gum but still the effect of PVP K 30 is noteworthy. PVP K 30 has indirect effect on all the factors by increasing tensile strength and making the tablet firm and intact.

  15. Evaluation of Matrix9 silicon photomultiplier array for small-animal PET

    PubMed Central

    Du, Junwei; Schmall, Jeffrey P.; Yang, Yongfeng; Di, Kun; Roncali, Emilie; Mitchell, Gregory S.; Buckley, Steve; Jackson, Carl; Cherry, Simon R.

    2015-01-01

    Purpose: The MatrixSL-9-30035-OEM (Matrix9) from SensL is a large-area silicon photomultiplier (SiPM) photodetector module consisting of a 3 × 3 array of 4 × 4 element SiPM arrays (total of 144 SiPM pixels) and incorporates SensL’s front-end electronics board and coincidence board. Each SiPM pixel measures 3.16 × 3.16 mm2 and the total size of the detector head is 47.8 × 46.3 mm2. Using 8 × 8 polished LSO/LYSO arrays (pitch 1.5 mm) the performance of this detector system (SiPM array and readout electronics) was evaluated with a view for its eventual use in small-animal positron emission tomography (PET). Methods: Measurements of noise, signal, signal-to-noise ratio, energy resolution, flood histogram quality, timing resolution, and array trigger error were obtained at different bias voltages (28.0–32.5 V in 0.5 V intervals) and at different temperatures (5 °C–25 °C in 5 °C degree steps) to find the optimal operating conditions. Results: The best measured signal-to-noise ratio and flood histogram quality for 511 keV gamma photons were obtained at a bias voltage of 30.0 V and a temperature of 5 °C. The energy resolution and timing resolution under these conditions were 14.2% ± 0.1% and 4.2 ± 0.1 ns, respectively. The flood histograms show that all the crystals in the 1.5 mm pitch LSO array can be clearly identified and that smaller crystal pitches can also be resolved. Flood histogram quality was also calculated using different center of gravity based positioning algorithms. Improved and more robust results were achieved using the local 9 pixels for positioning along with an energy offset calibration. To evaluate the front-end detector readout, and multiplexing efficiency, an array trigger error metric is introduced and measured at different lower energy thresholds. Using a lower energy threshold greater than 150 keV effectively eliminates any mispositioning between SiPM arrays. Conclusions: In summary, the Matrix9 detector system can resolve

  16. Different matrix evaluation for the bone regeneration of rats' femours using time domain optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Rusu, Laura-Cristina; Negrutiu, Meda Lavinia; Sinescu, Cosmin; Hoinoiu, Bogdan; Zaharia, Cristian; Ardelean, Lavinia; Duma, Virgil-Florin; Podoleanu, Adrian G.

    2014-01-01

    The osteoconductive materials are important in bone regeneration procedures. Three dimensional (3D) reconstructions were obtained from the analysis. The aim of this study is to investigate the interface between the femur rat bone and the new bone that is obtained using a method of tissue engineering that is based on two artificial matrixes inserted in previously artificially induced defects. For this study, under strict supervision 20 rats were used in conformity with ethical procedures. In all the femurs a round defect was induced by drilling with a 1 mm spherical Co-Cr surgical drill. The matrixes used were IngeniOss (for ten samples) and 4Bone(for the other ten samples). These materials were inserted into the induced defects. The femurs were investigated at 1 month, after the surgical procedures. The interfaces were examined using Time Domain (TD) Optical Coherence Tomography (OCT) combined with Confocal Microscopy (CM). The scanning procedure is similar to that used in any CM, where the fast scanning is en-face (line rate) and the scanning in depth is much slower (at the frame rate). The optical configuration uses two single mode directional couplers with a superluminiscent diode as the source centered at 1300 nm. The results showed open interfaces due to the insufficient healing process, as well as closed interfaces due to a new bone formation inside the defect. The conclusion of this study is that TD-OCT can act as a valuable tool in the investigation of the interface between the old bone and the one that has been newly created due to the osteoinductive process. The TD-OCT has proven a valuable tool for the non-invasive evaluation of the matrix bone interfaces.

  17. Radiographic and histological evaluation of ectopic application of deproteinized bovine bone matrix

    PubMed Central

    da Silva, Rodrigo Carlos; Crivellaro, Viviane Rozeira; Giovanini, Allan Fernando; Scariot, Rafaela; Gonzaga, Carla Castiglia; Zielak, João César

    2016-01-01

    Objective: To evaluate, through radiographic and histological analysis, the tissue reaction induced by a biomaterial based on deproteinized bovine bone matrix (DBBM) in the muscle of sheep. Materials and Methods: Sixteen sheep were used. The animals underwent surgery to insert polyethylene tubes containing the biomaterial in the muscle of the lower back (ectopic site) and were euthanized after 3 and 6 months. Each sheep received three tubes: Group 1 - sham group (negative control - tube without biomaterial), Group 2 - particulate autogenous bone (positive control), and Group 3 - DBBM biomaterial (GenOx Inorg). The material removed was evaluated by radiographic, macroscopic, and microscopic analysis, descriptively. Results: Macroscopic analysis showed that Group 3 had a greater tissue volume maintenance. Microscopic analysis indicated that Group 1 had a higher concentration of dense, thin collagen fibers (3 and 6 months); in Group 2, there was a decrease in the inflammatory process and the deposition of dense, thin collagen fibers (3 and 6 months); in Group 3, the presence of a dense connective tissue was noted, in which the DBBM particles (3 months) were found. On the periphery of these particles, a deposition of basophilic material was found, indicating the formation of mineral particles and the formation of tissues with osteoid characteristics (6 months). Conclusion: Based on the results obtained, it can be concluded that the biomaterial based on DBBM led to the formation of tissue with similar characteristics to an osteoid matrix in a postoperative period of 6 months. However, none of the groups evaluated showed ectopic bone neoformation. PMID:27563599

  18. Evaluation of several micromechanics models for discontinuously reinforced metal matrix composites

    NASA Technical Reports Server (NTRS)

    Johnson, W. Steven; Birt, M. J.

    1990-01-01

    A systematic experimental evaluation of whisker and particulate reinforced aluminum matrix composites was conducted to assess the variation in tensile properties with reinforcement type, volume fraction, and specimen thickness. Each material was evaluated in three thicknesses, 1.8, 3.18, and 6.35 mm, to determine the size, distribution, and orientation of the reinforcements. This information was used to evaluate several micromechanical models that predict composite moduli. The longitudinal and transverse moduli were predicted for reinforced aluminum. The Paul model, the Cox model and the Halpin-Tsai model were evaluated. The Paul model gave a good upper bound prediction for the particulate reinforced composites but under predicted whisker reinforced composite moduli. The Cox model gave good moduli predictions for the whisker reinforcement, but was too low for the particulate. The Halpin-Tsai model gave good results for both whisker and particulate reinforced composites. An approach using a trigonometric projection of whisker length to predict the fiber contribution to the modulus in the longitudinal and transverse directions was compared to the more conventional lamination theory approach.

  19. Evaluation of Ceramic Matrix Composite Technology for Aircraft Turbine Engine Applications

    NASA Technical Reports Server (NTRS)

    Halbig, Michael C.; Jaskowiak, Martha H.; Kiser, James D.; Zhu, Dongming

    2013-01-01

    The goals of the NASA Environmentally Responsible Aviation (ERA) Project are to reduce the NO(x) emissions, fuel burn, and noise from turbine engines. In order to help meet these goals, commercially-produced ceramic matrix composite (CMC) components and environmental barrier coatings (EBCs) are being evaluated as parts and panels. The components include a CMC combustor liner, a CMC high pressure turbine vane, and a CMC exhaust nozzle as well as advanced EBCs that are tailored to the operating conditions of the CMC combustor and vane. The CMC combustor (w/EBC) could provide 2700 F temperature capability with less component cooling requirements to allow for more efficient combustion and reductions in NOx emissions. The CMC vane (w/EBC) will also have temperature capability up to 2700 F and allow for reduced fuel burn. The CMC mixer nozzle will offer reduced weight and improved mixing efficiency to provide reduced fuel burn. The main objectives are to evaluate the manufacturability of the complex-shaped components and to evaluate their performance under simulated engine operating conditions. Progress in CMC component fabrication, evaluation, and testing is presented in which the goal is to advance from the proof of concept validation (TRL 3) to a system/subsystem or prototype demonstration in a relevant environment (TRL 6).

  20. An Analysis of Nondestructive Evaluation Techniques for Polymer Matrix Composite Sandwich Materials

    NASA Technical Reports Server (NTRS)

    Cosgriff, Laura M.; Roberts, Gary D.; Binienda, Wieslaw K.; Zheng, Diahua; Averbeck, Timothy; Roth, Donald J.; Jeanneau, Philippe

    2006-01-01

    Structural sandwich materials composed of triaxially braided polymer matrix composite material face sheets sandwiching a foam core are being utilized for applications including aerospace components and recreational equipment. Since full scale components are being made from these sandwich materials, it is necessary to develop proper inspection practices for their manufacture and in-field use. Specifically, nondestructive evaluation (NDE) techniques need to be investigated for analysis of components made from these materials. Hockey blades made from sandwich materials and a flat sandwich sample were examined with multiple NDE techniques including thermographic, radiographic, and shearographic methods to investigate damage induced in the blades and flat panel components. Hockey blades used during actual play and a flat polymer matrix composite sandwich sample with damage inserted into the foam core were investigated with each technique. NDE images from the samples were presented and discussed. Structural elements within each blade were observed with radiographic imaging. Damaged regions and some structural elements of the hockey blades were identified with thermographic imaging. Structural elements, damaged regions, and other material variations were detected in the hockey blades with shearography. Each technique s advantages and disadvantages were considered in making recommendations for inspection of components made from these types of materials.

  1. Human dental arch shape evaluated by euclidean-distance matrix analysis.

    PubMed

    Ferrario, V F; Sforza, C; Miani, A; Tartaglia, G

    1993-04-01

    Form differences between biological structures can be evaluated using several approaches. When landmark data are available, a recently proposed method (euclidean-distance matrix analysis) seems to be able to differentiate between size and shape differences. This method also localizes those areas which differ most between the two structures. We have applied it to analyze the sexual dimorphism in dental arch form in a sample of 50 men and 45 women. Subjects ranged in age between 20 and 27 years, and had sound dentitions. Fourteen landmarks, corresponding to the centers of gravity (centroids) of the occlusal surfaces of all permanent teeth (right second molar to left second molar), were individualized on the dental casts of subjects. All the possible linear distances between pairs of teeth were computed, thus creating four mean form matrices (one for each arch within sex). Gender differences were tested by using euclidean-distance matrix analysis. No significant differences were demonstrated in the shape of arches, while male arches proved to be slightly bigger than female arches.

  2. Evaluation of two matrix materials intended for fiber-reinforced polymers.

    PubMed

    Segerström, Susanna; Meriç, Gökçe; Knarvang, Torbjørn; Ruyter, I Eystein

    2005-10-01

    Two matrix resins for fiber composites that remain in a fluid state during storage and handling before polymerization were evaluated. The resin mixtures, based on methyl methacrylate (MMA), were produced with two different cross-linking agent systems: 1,4-butanediol dimethacrylate and ethylene glycol dimethacrylate or diethylene glycol dimethacrylate. Water sorption, water solubility, water uptake and residual MMA monomer were determined. Thermomechanical analysis was used to determine linear dimensional changes as a function of temperature. Flexural strength and modulus as well as fracture work and the maximum stress intensity factor were determined. The results revealed similar values for both matrix polymers regarding water sorption, water solubility, water uptake, residual MMA monomer (0.5 wt% (+/- 0.03)) and coefficient of linear thermal expansion. Flexural strength for polymer B was 68.7 MPa (+/- 9.8) compared to 56.0 MPa (+/- 13.3) for polymer A when tested dry and 64 MPa (+/- 6.1) compared to (54 MPa (+/- 3.3) when water-saturated. Fracture toughness tests showed higher maximum stress intensity factor values for polymer B (0.75 +/- 0.17) MPa x m1/2 than for polymer A (0.55 +/- 0.12) MPa x m1/2. The resin binders showed an appropriate consistency while remaining in a fluid state during storage and manipulation.

  3. Lornoxicam gastro retentive floating matrix tablets: Design and in vitro evaluation

    PubMed Central

    Sathiyaraj, S.; Devi, Ramya D.; Hari, Vedha B. N.

    2011-01-01

    The objective of this present investigation is to prolong the gastric residence time of Lornoxicam by fabricating it into a floating sustained release matrix tablets. Lornoxicam, a potent oxicam group of non-steroidal anti-inflammatory drugs, suffers from relatively short half life of 2 to 3 hrs showing maximal absorption in proximal gastro intestinal tract region necessitating its need to be formulated as a floating sustained release matrix tablets. In this current investigation, hydroxyl propyl methyl cellulose K15M, a high viscous grade polymer with apparent viscosity of 15,000 cps, was kept as a variable (10-50%) and calcium carbonate (13%) was used as a gas generator. The prepared blends were subjected for its pre-formulation characterization. The directly compressed tablets were evaluated for physical parameters such as weight uniformity, hardness, friability, drug content, in-vitro buoyancy with axial and radial enlargement measurement, swelling index. From the investigation it was observed that the buoyancy lasted for up to 24 hrs. Fourier transform infra-red spectroscopy peaks assured the compatibility of the drug with excipients and confirmed the presence of pure drug in the formulation. It was supported by in-vitro dissolution studies; and the dissolution data was subjected to various release kinetic models to understand the mechanism of drug release. PMID:22171312

  4. Evaluation of Johnson-Cook model constants for aluminum based particulate metal matrix composites

    NASA Astrophysics Data System (ADS)

    Hilfi, H.; Brar, N. S.

    1996-05-01

    High strain rate and high temperature response of three types of aluminum based particulate metal matrix ceramic composites is investigated by performing split Hopkinson pressure bar (SHPB) experiments. The composites are: NGP-2014 (15% SiC), NGT-6061 (15% SiC), and NGU-6061 (15% Al2O3), in which all the reinforcement materials are percentage by volume. Johnson-Cook constitutive model constants are evaluated from the high strain rate/high temperature data and implemented in a two dimensional finite element computer code (EPIC-2D) to simulate the penetration of an ogive nose tungsten projectile (23 grams) at a velocity 1.17 km/sec into the base 6061-T6 aluminum alloy and the composite NGU-6061. The simulated penetrations in the composite and in 6061-T6 aluminum agree with in 2%, in both materials, with the measured values.

  5. Algorithmic deformation of matrix factorisations

    NASA Astrophysics Data System (ADS)

    Carqueville, Nils; Dowdy, Laura; Recknagel, Andreas

    2012-04-01

    Branes and defects in topological Landau-Ginzburg models are described by matrix factorisations. We revisit the problem of deforming them and discuss various deformation methods as well as their relations. We have implemented these algorithms and apply them to several examples. Apart from explicit results in concrete cases, this leads to a novel way to generate new matrix factorisations via nilpotent substitutions, and to criteria whether boundary obstructions can be lifted by bulk deformations.

  6. Evaluation of the Technical-Economic Potential of Particle- Reinforced Aluminum Matrix Composites and Electrochemical Machining

    NASA Astrophysics Data System (ADS)

    Schubert, A.; Götze, U.; Hackert-Oschätzchen, M.; Lehnert, N.; Herold, F.; Meichsner, G.; Schmidt, A.

    2016-03-01

    Compared to conventional cutting, the processing of materials by electrochemical machining offers some technical advantages like high surface quality, no thermal or mechanical impact on the work piece and preservation of the microstructure of the work piece material. From the economic point of view, the possibility of process parallelization and the absence of any process-related tool wear are mentionable advantages of electrochemical machining. In this study, based on experimental results, it will be evaluated to what extent the electrochemical machining is technically and economically suitable for the finish-machining of particle- reinforced aluminum matrix composites (AMCs). Initial studies showed that electrochemical machining - in contrast to other machining processes - has the potential to fulfil demanding requirements regarding precision and surface quality of products or components especially when applied to AMCs. In addition, the investigations show that processing of AMCs by electrochemical machining requires less energy than the electrochemical machining of stainless steel. Therefore, an evaluation of electrochemically machined AMCs - compared to stainless steel - from a technical and an economic perspective will be presented in this paper. The results show the potential of electro-chemically machined AMCs and contribute to the enhancement of instruments for technical-economic evaluations as well as a comprehensive innovation control.

  7. Evaluation of Matrix9 silicon photomultiplier array for small-animal PET

    SciTech Connect

    Du, Junwei Schmall, Jeffrey P.; Yang, Yongfeng; Di, Kun; Roncali, Emilie; Mitchell, Gregory S.; Buckley, Steve; Jackson, Carl; Cherry, Simon R.

    2015-02-15

    Purpose: The MatrixSL-9-30035-OEM (Matrix9) from SensL is a large-area silicon photomultiplier (SiPM) photodetector module consisting of a 3 × 3 array of 4 × 4 element SiPM arrays (total of 144 SiPM pixels) and incorporates SensL’s front-end electronics board and coincidence board. Each SiPM pixel measures 3.16 × 3.16 mm{sup 2} and the total size of the detector head is 47.8 × 46.3 mm{sup 2}. Using 8 × 8 polished LSO/LYSO arrays (pitch 1.5 mm) the performance of this detector system (SiPM array and readout electronics) was evaluated with a view for its eventual use in small-animal positron emission tomography (PET). Methods: Measurements of noise, signal, signal-to-noise ratio, energy resolution, flood histogram quality, timing resolution, and array trigger error were obtained at different bias voltages (28.0–32.5 V in 0.5 V intervals) and at different temperatures (5 °C–25 °C in 5 °C degree steps) to find the optimal operating conditions. Results: The best measured signal-to-noise ratio and flood histogram quality for 511 keV gamma photons were obtained at a bias voltage of 30.0 V and a temperature of 5 °C. The energy resolution and timing resolution under these conditions were 14.2% ± 0.1% and 4.2 ± 0.1 ns, respectively. The flood histograms show that all the crystals in the 1.5 mm pitch LSO array can be clearly identified and that smaller crystal pitches can also be resolved. Flood histogram quality was also calculated using different center of gravity based positioning algorithms. Improved and more robust results were achieved using the local 9 pixels for positioning along with an energy offset calibration. To evaluate the front-end detector readout, and multiplexing efficiency, an array trigger error metric is introduced and measured at different lower energy thresholds. Using a lower energy threshold greater than 150 keV effectively eliminates any mispositioning between SiPM arrays. Conclusions: In summary, the Matrix9 detector system

  8. In vitro and in vivo evaluation of guar gum-based matrix tablets of rofecoxib for colonic drug delivery.

    PubMed

    Al-Saidan, S M; Krishnaiah, Y S R; Satyanarayana, V; Rao, G S

    2005-04-01

    The present study was carried out to develop and evaluate guar gum-based matrix tablets of rofecoxib for their intended use in the chemoprevention of colorectal cancer. Matrix tablets containing 40% (RXL-40), 50% (RXL-50), 60% (RXL-60) or 70% (RXL-70) of guar gum were prepared by wet granulation technique, and were subjected to in vitro drug release studies. Guar gum matrix tablets released only 5 to 12% of rofecoxib in the physiological environment of stomach and small intestine. The matrix tablets RXL-40 disintegrated completely within 10 h in a dissolution medium without rat caecal contents (control study), and hence not studied further. When the dissolution study was continued in simulated colonic fluids (rat caecal content medium), the matrix tablets RXL-50 were acted upon by colonic bacterial enzymes releasing the entire quantity of drug wherein there was no appreciable difference when compared to that released in control study. The matrix tablets RXL-60 released another 88% of rofecoxib whereas matrix tablets RXL-70 released only 57% of rofecoxib in simulated colonic fluids indicating the susceptibility of the guar gum formulations to the rat caecal contents. The guar gum matrix tablets RXL-70 were subjected to in vivo evaluation in human volunteers to find their ability of targeting rofecoxib to colon. The delayed Tmax, prolonged absorption time (ta), decreased Cmax and decreased ka indicated that rofecoxib was not released significantly in stomach and small intestine, but was delivered to colon resulting in a slow absorption of the drug and making it available for local action in human colon.

  9. Evaluation of the biological responses of osteoblast-like UMR-106 cells to the engineered porous PHBV matrix.

    PubMed

    Liu, Hui; Raghavan, Dharmaraj; Stubbs, John

    2007-06-01

    Poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) has been investigated for biomedical applications due to its many biologically favorable properties. However, to explore its application in bone tissue engineering, the poorly bioactive surface property of PHBV must be improved. To engineer PHBV to achieve a biologically active surface, in this study each porous PHBV matrix was prepared by solute leaching of salt/PHBV cast film and was treated with ozone followed by dip coating with type I collagen. The biological responses of osteoblast-like UMR-106 cells after being grown on the engineered PHBV matrix were evaluated. Confocal microscopy and the MTT assay were used to map and quantify the viable cell proliferation on the PHBV matrix, respectively. The cells were cultivated in osteogenic media containing beta-glycerophosphate and later stained with alizarin red to visualize mineralization of the matrix. RNA was extracted from the UMR-106 cells, and reverse transcriptase-polymerase chain reaction (RT-PCR) was applied to detect expression of glyceraldehyde 3-phosphate dehydrogenase (GAPDH) (a house keeping gene) and bone sialoprotein (BSP) (marker of the osteoblastic phenotype). The results showed that the UMR-106 cells after cultivation on the engineered PHBV matrix retained the osteoblastic phenotype characteristics, indicating that the porous PHBV matrix after ozone treatment and collagen dip coatings are a promising scaffold for bone tissue engineering applications.

  10. R-Matrix Evaluation of {sup 16}O neutron cross sections up to 6.3 MeV

    SciTech Connect

    Sayer, R.O.; Leal, L.C.; Larson, N.M.; Spencer, R.R.; and Wright, R.Q.

    2000-08-01

    In this paper the authors describe an evaluation of {sup 16}O neutron cross sections in the resolved resonance region with the multilevel Reich-Moore R-matrix formalism. Resonance analyses were performed with the computer code SAMMY [LA98] which utilizes Bayes' method, a generalized least squares technique.

  11. Dental arch asymmetry in young healthy human subjects evaluated by Euclidean distance matrix analysis.

    PubMed

    Ferrario, V F; Sforza, C; Miani, A; Serrao, G

    1993-03-01

    Form differences between biological structures can be evaluated using several approaches. A recently proposed method (Euclidean distance matrix analysis; EDMA) seems to be able to differentiate between size and shape differences. Here it has been applied to study the asymmetry of mandibular and maxillary arches in 50 men and 45 women with sound dentitions. The centres of gravity (centroids) of the occlusal surfaces of all permanent teeth (right second molar to left second molar) were individualized on the dental casts of subjects. The form of the right and left maxillary and mandibular hemi-arches was separately assessed by calculating all the possible linear distances between pairs of teeth within arch and side. Side differences were tested by EDMA. In men, the maxillary and the mandibular arches were both symmetrical (i.e. there were no significant differences in size or shape between the left and right hemi-arches). In women, the mandibular arch was symmetrical, but in the maxillary arch the two antimeres had a significantly different shape. No size differences were found between the left and right female hemi-arches.

  12. Fabrication and biological evaluation of uniform extracellular matrix coatings on discontinuous photolithography generated micropallet arrays

    PubMed Central

    Gunn, Nicholas M.; Bachman, Mark; Li, Guann-Pyng; Nelson, Edward L.

    2010-01-01

    ABSTRACT/SYNOPSIS The recent identification of rare cell populations within tissues that are associated with specific biological behaviors, e.g., progenitor cells, has illuminated a limitation of current technologies to study such adherent cells directly from primary tissues. The micropallet array is a recently developed technology designed to address this limitation by virtue of its capacity to isolate and recover single adherent cells on individual micropallets. The capacity to apply this technology to primary tissues and cells with restricted growth characteristics, particularly adhesion requirements, is critically dependent upon the capacity to generate functional extracellular matrix (ECM) coatings. The discontinuous nature of the micropallet array surface provides specific constraints on the processes for generating the desired ECM coatings that are necessary to achieve the full functional capacity of the micropallet array. We have developed strategies, reported herein, to generate functional coatings with various ECM protein components: fibronectin, EHS tumor basement membrane extract, collagen, and laminin-5; confirmed by evaluation for rapid cellular adherence of four dissimilar cell types: fibroblast, breast epithelial, pancreatic epithelial, and myeloma. These findings are important for the dissemination and expanded use of micropallet arrays and similar microtechnologies requiring the integrated use of ECM protein coatings to promote cellular adherence. PMID:20648537

  13. Semi solid matrix formulations of meloxicam and tenoxicam: an in vitro and in vivo evaluation.

    PubMed

    Alladi, Saritha; Shastri, Nalini R

    2015-01-01

    The objective of this study was to improve the dissolution and subsequently the therapeutic efficacy of poorly water soluble BCS class-II drugs meloxicam and tenoxicam, by lipid semi solid matrix (SSM) systems filled in hard gelatin capsules by liquid fill technology. The present research involved preparation of SSM formulations using Gelucire 44/14 as a carrier due to its self emulsifying, wetting and hydrophilic properties. The SSM capsules were characterized by assay, in vitro dissolution studies, moisture uptake, FTIR and DSC. The optimized formulations were also evaluated for their in vivo anti inflammatory activity in rat model. Six to ten fold enhancement in vitro drug release, in both acidic and basic media, was obtained with formulations containing drug to carrier in 1:6 ratio. The absence of drug peak in DSC scans indicated complete dissolution of the drug in carrier, while IR revealed no chemical interaction of pure drug and Gelucire 44/14. The optimized SSM formulations of meloxicam and tenoxicam showed a rapid decrease in paw edema with a significant increase in anti-inflammatory activity. The SSM formulations were successful in providing rapid release of drugs with improved dissolution and in vivo anti-inflammatory activity by liquid fill technology in hard gelatin capsules.

  14. High-precision evaluation of Wigner's d matrix by exact diagonalization.

    PubMed

    Feng, X M; Wang, P; Yang, W; Jin, G R

    2015-10-01

    The precise calculations of Wigner's d matrix are important in various research fields. Due to the presence of large numbers, direct calculations of the matrix using Wigner's formula suffer from a loss of precision. We present a simple method to avoid this problem by expanding the d matrix into a complex Fourier series and calculate the Fourier coefficients by exactly diagonalizing the angular momentum operator J(y) in the eigenbasis of J(z). This method allows us to compute the d matrix and its various derivatives for spins up to a few thousand. The precision of the d matrix from our method is about 10(-14) for spins up to 100.

  15. Preclinical evaluation of a novel abluminal surface coated sirolimus eluting stent with biodegradable polymer matrix

    PubMed Central

    Doshi, Manish; Galloni, Marco; Vignolini, Christina; Vyas, Ashwin; Chevli, Bhavesh; Sheiban, Imad

    2015-01-01

    Background Second generation of drug eluting stents (DES) has attempted to improve safety using abluminal sirolimus drug delivery with biodegradable polymers matrix. The present preclinical study was designed to investigate the safety and efficacy profile of Abluminus™ stents (SES). This is a new coronary stent with sirolimus and biodegradable polymer matrix coated on abluminal stent and balloon surface. Methods SES were compared with two controls: bare metal stent (BMS) and BMS + polymer coated stents (PC). All devices (40 stents) were implanted in porcine coronary arteries with primary endpoint of endothelialization at 7 days and subsequent histological and morphometric evaluations at 7, 30 and 90 days. Results Early endothelialization at seven days was complete in all stents. Histology at 30 days revealed minimum inflammation in all groups and increased at 90 days in PC group while it was absent at 180 days. Thirty day morphometry showed significantly reduction of neointimal area in Abluminus™ (SES 0.96±0.48 mm2; BMS 1.83±0.34 mm2; PC 1.76±0.55 mm2; P<0.05); after 90 days neointimal area was 1.10±0.54 mm2 for SES; 1.92±0.36 mm2 for BMS; and 1.94±0.48 mm2 for PC; P<0.05). Neointimal thickness at 30 and 90 days respectively was 0.15±0.07 and 0.18±0.10 mm for SES, 0.57±0.08 and 0.61±0.09 mm for BMS and 0.52±0.09 and 0.59±0.08 mm, P<0.001 for PC group. Conclusions The most significant experimental evidence appears to be earlier endothelialization at 7 days for SES which led to safety of the device. Efficacy of the device was also observed by a reduced neointimal thickness and minimized inflammatory score at all follow-ups. Termination of antiplatelet at 30 days has not shown any further complications. Polymer thickness was almost in negligible amount at 180 days with no inflammation. PMID:26331109

  16. Brezinaite Revisited

    NASA Astrophysics Data System (ADS)

    Davis, D. E.

    1993-07-01

    Brezinaite Data: Idealized formula: (Cr^2+Cr^3+)(sub)3S(sub)4, metal: sulphur ratio=0.76 - 0.79, structure: defect NiAs-type, symmetry: monoclinic I 2/m, Beta = 91 degrees 32'. As part of a research program in Copenhagen and at the Smithsonian Institution involving sulphides in selected irons, the mineral brezinaite was, quite surprisingly, found to be present in several of the sections studied. Brezinaite is a rare meteoritic sulphide, previously only reported in two Anom. irons; Tucson [1] and New Baltimore [2] , a list that can now be extended to include, as a minimum, the following meteorites: Type IIIA; Costilla Peak, Kalkaska and Murfreesboro. Type IVA; Jamestown, La Grange and Western Arkansas. Anom. or type IIIF; Saint Genevieve County. A thin section examination by reflected light alone will not always be enough to identify the mineral with sufficient accuracy, and it is, therefore, only meteorites in which brezinaite has been confirmed by microprobe analysis that are mentioned above. With the exception of Tucson, where brezinaite is frequently found as anhedral grains contiguous to silicate inclusions, its typical occurrence is either in or along sub-boundaries of the kamacite bands, or occasionally within comb- structured plessite fields. Brezinaite appears most commonly as minute (5-200 micrometers) anhedral-subhedral greyish colored grains, occasionally with a partial rim of schreibersite (eg., Murfreesboro), that occur freely scattered throughout the metal matrix. With the notable exception of troilite aggregates, in which brezinaite does not occur, its appearance and occurrence coincide with the common mineral daubreelite (VH~400 and R% = 37- 40). The difficulty in distinguishing between these two minerals has been a source of confusion. The present study shows that the two minerals both occur as isolated grains and in the immediate vicinity of each other. The intimate relationship between the two minerals is especially clear in Costilla Peak where

  17. Mere Exposure Revisited: The Influence of Growth versus Security Cues on Evaluations of Novel and Familiar Stimuli

    ERIC Educational Resources Information Center

    Gillebaart, Marleen; Forster, Jens; Rotteveel, Mark

    2012-01-01

    Combining regulatory focus theory (Higgins, 1997) and novelty categorization theory (Forster, Marguc, & Gillebaart, 2010), we predicted that novel stimuli would be more positively evaluated when focused on growth as compared with security and that familiar stimuli would be more negatively evaluated when focused on growth as compared with security.…

  18. Automated evaluation of matrix elements between contracted wavefunctions: A Mathematica version of the FRODO program

    NASA Astrophysics Data System (ADS)

    Angeli, C.; Cimiraglia, R.

    2013-02-01

    A symbolic program performing the Formal Reduction of Density Operators (FRODO), formerly developed in the MuPAD computer algebra system with the purpose of evaluating the matrix elements of the electronic Hamiltonian between internally contracted functions in a complete active space (CAS) scheme, has been rewritten in Mathematica. New version : A program summaryProgram title: FRODO Catalogue identifier: ADV Y _v2_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADVY_v2_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.: 3878 No. of bytes in distributed program, including test data, etc.: 170729 Distribution format: tar.gz Programming language: Mathematica Computer: Any computer on which the Mathematica computer algebra system can be installed Operating system: Linux Classification: 5 Catalogue identifier of previous version: ADV Y _v1_0 Journal reference of previous version: Comput. Phys. Comm. 171(2005)63 Does the new version supersede the previous version?: No Nature of problem. In order to improve on the CAS-SCF wavefunction one can resort to multireference perturbation theory or configuration interaction based on internally contracted functions (ICFs) which are obtained by application of the excitation operators to the reference CAS-SCF wavefunction. The previous formulation of such matrix elements in the MuPAD computer algebra system, has been rewritten using Mathematica. Solution method: The method adopted consists in successively eliminating all occurrences of inactive orbital indices (core and virtual) from the products of excitation operators which appear in the definition of the ICFs and in the electronic Hamiltonian expressed in the second quantization formalism. Reasons for new version: Some years ago we published in this journal a couple of papers [1, 2

  19. Evaluation of roll compaction as a preparation method for hydroxypropyl cellulose-based matrix tablets

    PubMed Central

    Jeon, Imjak; Gilli, Tiziana; Betz, Gabriele

    2011-01-01

    Roll compaction was applied for the preparation of hydroxypropyl cellulose (HPC)-based sustained-release matrix tablets. Matrix tablets made via roll compaction exhibited higher dosage uniformity and faster drug release than direct-compacted tablets. HPC viscosity grade, roll pressure, and milling speed affected tablet properties significantly. Roll compaction seems to be an adequate granulation method for the preparation of HPC-based matrix tablets due to the simplicity of the process, less handling difficulty from HPC tackiness as well as easier particle size targeting. Selecting the optimum ratio of plastic excipients and the particle size of starting materials can however be critical issues in this method. PMID:21687348

  20. Handling, clamping, and alignment evaluation for multi-beam technology on Matrix1.1 platform

    NASA Astrophysics Data System (ADS)

    Lattard, Ludovic; Pradelles, Jonathan; Vergeer, Niels; Slot, Erwin; Pain, Laurent; de Jong, Erik; Torriani, Gianpaolo; Pieczulewski, Charles

    2014-04-01

    The MATRIX platform integrates new types of modules for handling and alignment capability and this represents two new and innovative aspects for multi-beam lithography. Results on performances in terms of robustness of the different modules in real manufacturing conditions, including the interface of the MATRIX platform with the SOKUDO DUO track will be reported. A new type of alignment solution was developed by MAPPER. This paper will show the first results on alignment sensor repeatability. Preliminary results on the overlay performance of the MATRIX platform will be presented and discussion will be engaged to position the MAPPER alignment concept with respect to the ITRS roadmap expectations.

  1. Histological and radiographic evaluations of demineralized bone matrix and coralline hydroxyapatite in the rabbit tibia.

    PubMed

    Zhukauskas, Rasa; Dodds, Robert A; Hartill, Caroline; Arola, Travis; Cobb, Ronald R; Fox, Casey

    2010-03-01

    Complex fractures resulting in bone loss or impaired fracture healing remain problematic in trauma and orthopedic surgeries. Many bone graft substitutes have been developed and are commercially available. These products differ in their osteoconductive and osteoinductive properties. Differential enhancement of these properties may optimize the performance of these products for various orthopedic and craniofacial applications. The use of bone graft substitutes offers the ability to lessen the possible morbidity of the harvest site in autografts. The objective of the present study was to compare the ability of two bone graft substitutes, BioSet RT, an allograft demineralized bone matrix formulation, and ProOsteon 500R, a coralline hydroxyapatite, in a rabbit critical tibial defect model. BioSet RT and ProOsteon 500R were implanted into a unicortical proximal metaphyseal tibial defect and evaluated for new bone formation. Samples were analyzed radiographically and histologically at 1 day, 6 weeks, 12 weeks, and 24 weeks post surgery. Both materials were biocompatible and demonstrated significant bone growth and remodeling. At 12 weeks, the BioSet RT implanted sites demonstrated significantly more defect closure and bone remodeling as determined by radiographic analyses with 10 out of 14 defects being completely healed versus 1 out of 14 being completely healed in the ProOsteon 500R implanted sites. At 24 weeks, both materials demonstrated complete closure of the defect as determined histologically. There were no statistical differences in radiographic scores between the two implanted materials. However, there was an observable trend that the BioSet RT material generated higher histological and radiographic scores, although not statistically significant. This study provides evidence that both BioSet RT and ProOsteon 500R are biocompatible and able to induce new bone formation as measured in this rabbit model. In addition, this in vivo study demonstrates the ability of

  2. Evaluation of two fast and easy methods for pesticide residue analysis in fatty food matrixes.

    PubMed

    Lehotay, Steven J; Mastovská, Katerina; Yun, Seon Jong

    2005-01-01

    Two rapid methods of sample preparation and analysis of fatty foods (e.g., milk, eggs, and avocado) were evaluated and compared for 32 pesticide residues representing a wide range of physicochemical properties. One method, dubbed the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method for pesticide residue analysis, entailed extraction of 15 g sample with 15 mL acetonitrile (MeCN) containing 1% acetic acid followed by addition of 6 g anhydrous magnesium sulfate and 1.5 g sodium acetate. After centrifugation, 1 mL of the buffered MeCN extract underwent a cleanup step (in a technique known as dispersive solid-phase extraction) using 50 mg each of C18 and primary secondary amine sorbents plus 150 mg MgSO4. The second method incorporated a form of matrix solid-phase dispersion (MSPD), in which 0.5 g sample plus 2 g C18 and 2 g anhydrous sodium sulfate was mixed in a mortar and pestle and added above a 2 g Florisil column on a vacuum manifold. Then, 5 x 2 mL MeCN was used to elute the pesticide analytes from the sample into a collection tube, and the extract was concentrated to 0.5 mL by evaporation. Extracts in both methods were analyzed concurrently by gas chromatography/mass spectrometry and liquid chromatography/tandem mass spectrometry. The recoveries of semi-polar and polar pesticides were typically 100% in both methods (except that basic pesticides, such as thiabendazole and imazalil, were not recovered in the MSPD method), but recovery of nonpolar pesticides decreased as fat content of the sample increased. This trend was more pronounced in the QuEChERS method, in which case the most lipophilic analyte tested, hexachlorobenzene, gave 27 +/- 1% recovery (n=6) in avocado (15% fat) with a<10 ng/g limit of quantitation.

  3. Evaluation of Topical Hesperetin Matrix film for Back-of-the-Eye Delivery

    PubMed Central

    Adelli, Goutham R.; Hingorani, Tushar; Punyamurthula, Nagendra; Balguri, Sai Prachetan; Majumdar, Soumyajit

    2015-01-01

    Purpose The goal of the present study is to develop a poly (ethylene oxide) N10 (PEO N10) based melt-cast matrix system for efficient and prolonged delivery of hesperetin (HT), a promising bioflavonoid, to the posterior segment of the eye through the topical route. Methods HT film was prepared by melt-cast method using PEO N10 and cut into 4 mm × 2 mm segments, each weighing 8 mg. This film was evaluated with respect to in vitro release rates and also transmembrane delivery across Spectra/Por® membrane (MWCO: 10000 Daltons) and isolated rabbit corneas. Ocular tissue concentrations were also determined post application of the film in ex vivo and in vivo models. Results HT release from the film was determined to be about 95.3 % within 2 h. In vitro transcorneal flux was observed to be 0.58 ± 0.05 μg/min/cm2 across the isolated rabbit cornea. High levels of HT were detected in the retina-choroid (RC) and vitreous humor (VH) in the ex vivo model following topical application of the film. Significant levels of HT were observed in both anterior and posterior segment ocular tissues 1h post topical application of the 10 and 20 %w/w HT films on the rabbit eye. Moreover, HT was detected in the VH and RC even after 6h following topical application of the film in vivo. Conclusion The results from this study suggest that the melt-cast films can serve as a viable platform for sustained topical delivery of bioflavonoids, and other therapeutic agents, into the back-of-the eye tissues. PMID:25728824

  4. Preparation and in vitro evaluation of guar gum based triple-layer matrix tablet of diclofenac sodium

    PubMed Central

    Chavda, H.V.; Patel, M.S.; Patel, C.N.

    2012-01-01

    The objective of the present study was to design an oral controlled drug delivery system for sparingly soluble diclofenac sodium (DCL) using guar gum as triple-layer matrix tablets. Matrix tablet granules containing 30% (D1), 40% (D2) or 50% (D3) of guar gum were prepared by the conventional wet granulation technique. Matrix tablets of diclofenac sodium were prepared by compressing three layers one by one. Centre layer of sandwich like structure was incorporated with matrix granules containing DCL which was covered on either side by guar gum granule layers containing either 70, 80 or 87% of guar gum as release retardant layers. The tablets were evaluated for hardness, thickness, drug content, and drug release studies. To ascertain the kinetics of drug release, the dissolution profiles were fitted to various mathematical models. The in vitro drug release from proposed system was best explained by the Hopfenberg model indicating that the release of drug from tablets displayed heterogeneous erosion. D3G3, containing 87% of guar gum in guar gum layers and 50% of guar gum in DCL matrix granule layer was found to provide the release rate for prolonged period of time. The results clearly indicate that guar gum could be a potential hydrophilic carrier in the development of oral controlled drug delivery systems. PMID:23181081

  5. Iodine revisited.

    PubMed

    Cooper, Rose A

    2007-06-01

    Iodine is an antiseptic that has been used in wound care for more than 150 years. Traditional formulations of iodine had serious limitations that were reduced in later products. Much has been written about iodine and opinions on its clinical efficacy are divided. There have been reviews of the chemical properties of iodine, its antimicrobial activity, human physiology, cytotoxicity and its clinical effectiveness, but few have addressed all these aspects. With the recent development of iodine-containing wound care products and the continued publication of laboratory and clinical studies, it seems timely to reassess the evidence relating to the effectiveness of iodine for treating wounds. This literature review attempts to provide an appropriate chemical and physiological background of the characteristics of iodine in order to provide a sound basis for understanding the available microbiological and clinical data. It will show that understanding the factors that contribute to the activity and potential cytotoxicity of iodine are important in evaluating the clinical evidence. Although definitive studies are needed, the sustained delivery of low doses of free iodine offers the potential to inhibit a broad range of microbial species without selecting for resistant strains or inducing cytotoxic effects.

  6. STATISTICAL EVALUATION OF PROCESSING DATA FROM THE RH RU HG MATRIX STUDY

    SciTech Connect

    Koopman, D

    2009-04-17

    An evaluation of the statistical significance of Rh, Ru, and Hg on DWPF Sludge Receipt and Adjustment Tank (SRAT) cycle catalytic hydrogen generation and process chemistry was conducted by the Savannah River National Laboratory (SRNL) using a full-factorial experimental design. This test design can identify significant interactions between these three species in addition to individual effects. Statistical modeling of data from the Rh-Ru-Hg matrix study has been completed. Preliminary data and conclusions were given in an earlier report. This final report concludes the work on the Rh-Ru-Hg matrix study. Modeling results are summarized below. Rhodium was found to: Promote increased total hydrogen mass; Promote an increase in the maximum hydrogen generation rate; Promote an increase in the hydrogen generation rate shortly after acid addition; Shorten the elapsed time between acid addition and the maximum hydrogen generation rate; Increase formate loss; Inhibit NO{sub 2} and total NO{sub x} off-gas species formation; and Reduce nitrite-to-nitrate conversion. Ruthenium was found to: Promote increased total hydrogen mass; Promote an increase in the maximum hydrogen generation rate; Promote an increase in the hydrogen generation rate in the second half of the SRAT cycle; Promote an increase in total CO{sub 2} generated; Increase formate loss; Promote NO{sub 2} and total NO{sub x} off-gas species formation; and Reduce nitrite-to-nitrate conversion. Mercury was found to: Inhibit total hydrogen mass produced; Promote an increase in total CO{sub 2} generated; Promote NO{sub 2} off-gas species formation; and Inhibit total NO{sub x} off-gas species formation. Results confirmed qualitative observations that Rh was activating before Ru for hydrogen generation. An interaction between Rh and Ru was present in the model for the total hydrogen generated during the SRAT, perhaps because the total combined contributions from two separate episodes of hydrogen generation. The first

  7. Revisiting Insights from Three Mile Island Unit 2 Postaccident Examinations and Evaluations in View of the Fukushima Daiichi Accident

    SciTech Connect

    Rempe, Joy; Farmer, Mitchell; Corradini, Michael; Ott, Larry; Gauntt, Randall; Powers, Dana

    2012-11-01

    The Three Mile Island Unit 2 (TMI-2) accident, which occurred on March 28, 1979, led industry and regulators to enhance strategies to protect against severe accidents in commercial nuclear power plants. Investigations in the years after the accident concluded that at least 45% of the core had melted and that nearly 19 tonnes of the core material had relocated to the lower head. Postaccident examinations indicate that about half of that material formed a solid layer near the lower head and above it was a layer of fragmented rubble. As discussed in this paper, numerous insights related to pressurized water reactor accident progression were gained from postaccident evaluations of debris, reactor pressure vessel (RPV) specimens, and nozzles taken from the RPV. In addition, information gleaned from TMI-2 specimen evaluations and available data from plant instrumentation were used to improve severe accident simulation models that form the technical basis for reactor safety evaluations. Finally, the TMI-2 accident led the nuclear community to dedicate considerable effort toward understanding severe accident phenomenology as well as the potential for containment failure. Because available data suggest that significant amounts of fuel heated to temperatures near melting, the events at Fukushima Daiichi Units 1, 2, and 3 offer an unexpected opportunity to gain similar understanding about boiling water reactor accident progression. To increase the international benefit from such an endeavor, we recommend that an international effort be initiated to (a) prioritize data needs; (b) identify techniques, samples, and sample evaluations needed to address each information need; and (c) help finance acquisition of the required data and conduct of the analyses.

  8. Evaluation of horizontal ridge augmentation using beta tricalcium phosphate and demineralized bone matrix: A comparative study

    PubMed Central

    Shalash, Mahmoud A.; Rahman, Hatem A.; Azim, Amr A.; Neemat, Amani H.; Hawary, Hesham E.

    2013-01-01

    Objectives: To evaluate the effectiveness of beta tricalcium phosphate (β-TCP) alone compared to β-TCP and Demineralized Bone Matrix (DBM) in regenerating localized horizontal maxillary alveolar ridge deficiencies prior to implant placement. Study Design: The study included 20 patients with horizontal maxillary ridge deficiencies limited to one or more neighbouring teeth and initial ridge width of ≤ 5mmm. Patients were divided equally into two equal groups. Ridge augmentation was performed using Guided Bone Regeneration (GBR) principals. In group I GBR was performed using β-TCP only, while in group II both β-TCP and DBM were used. Following a 6 months healing period, bone cores from both groups were retrieved and implants were inserted. Specimens were examined histologically to calculate percentage of mineralized bone. Apical and crestal changes in ridge dimensions were calculated by digital subtraction using Cone Beam Computed Tomography (CBCT) immediately after graft placement and six months later. Results: There was a statistically significant difference between the mean area percentage of mineralized bone between both groups where it was 40.1 % (range: 27.76-% 66.29 %) for group I and 68.96 % (range: 60.07 % - 87.33 %) for group II. Radiograpically, the mean ridge width in group I increased crestally to 4.66 mm (range:3.5-5mm) and apically to 6.12 mm (range: 4.1-6.7 mm). In group II the mean ridge width increased crestally to 5.2 mm (range 4.9-5.4mm) and apically to 6.9 mm (range 6.0-7.8 mm). Group II showed more bone gain with a mean of 1.37 mm crestally and 2.44 mm apically. This difference however was not statistically significant Conclusion: Within the limitations of this study the combination of DBM and β-TCP can be used effectively in cases exhibiting minimal alveolar ridge defects. Key words:Guided bone regeneration, equine bone, alloplast, bone graft. PMID:24455091

  9. Evaluation of Matrix Metalloproteinase 7 in Plasma and Pancreatic Juice as a Biomarker for Pancreatic Cancer

    PubMed Central

    Kuhlmann, Koert F.D.; van Till, J.W. Olivier; Boermeester, Marja A.; de Reuver, Philip R.; Tzvetanova, Iva D.; Offerhaus, G. Johan A.; ten Kate, Fiebo J.W.; Busch, Olivier R.C.; van Gulik, Thomas M.; Gouma, Dirk J.; Crawford, Howard C.

    2015-01-01

    Differentiating between periampullary carcinoma and chronic pancreatitis with an inflammatory mass is difficult. Consequently, 6% to 9% of pancreatic resections for suspected carcinoma are done inappropriately for chronic pancreatitis. Here, we test if matrix metalloproteinase 7 (MMP-7), a secreted protease frequently expressed in pancreatic carcinoma, can be measured in plasma, pancreatic, and duodenal juice, and if it can distinguish between periampullary carcinoma and chronic pancreatitis. Ninety-four patients who underwent pancreatic surgery for a (peri)pancreatic neoplasm (n = 63) or chronic pancreatitis (n = 31) were analyzed. Median plasma MMP-7 levels were significantly higher in carcinoma (1.95 ng/mL; interquartile range, 0.81–3.22 ng/mL) compared with chronic pancreatitis and benign disease (0.83 ng/mL; interquartile range, 0.25–1.21 ng/mL; P < 0.01). MMP-7 levels in pancreatic juice were higher, although not significantly, in carcinoma (62 ng/mg protein; interquartile range, 18–241 ng/mg protein) compared with chronic pancreatitis and benign disease (23 ng/mg protein; interquartile range, 8.5–99 ng/mg protein; P = 0.17). MMP-7 levels in duodenal juice were universally low. At an arbitrary cutoff of 1.5 ng/mL in plasma, positive and negative predictive values were 83% and 57%, respectively, values comparable to those of today’s most common pancreatic tumor marker, carbohydrate antigen 19-9 (CA19-9; 83% and 53%, respectively). Positive and negative likelihood ratios for plasma MMP-7 were 3.35 and 0.52, respectively. The area under the receiver operating characteristic curve for MMP-7 was 0.73 (95% confidence interval, 0.63–0.84) and for CA19-9, 0.75 (95% confidence interval, 0.64–0.85). Combined MMP-7 and CA19-9 assessment gave a positive predictive value of 100%. Thus, plasma MMP-7 levels discriminated between patients with carcinoma and those with chronic pancreatitis or benign disease. The diagnostic accuracy of plasma MMP-7 alone is not

  10. Escitalopram dose-response revisited: an alternative psychometric approach to evaluate clinical effects of escitalopram compared to citalopram and placebo in patients with major depression.

    PubMed

    Bech, Per; Tanghøj, Per; Cialdella, Philippe; Andersen, Henning Friis; Pedersen, Anders Gersel

    2004-09-01

    In continuation of a previous psychometric analysis of dose-response data for citalopram in depression, the corresponding study data for escitalopram is of interest, since escitalopram is the active enantiomer of citalopram and because citalopram was used as the active control. Revisiting those corresponding data, the psychometric properties of the Montgomery-Asberg Depression Scale (MADRS) and the Hamilton Depression Scale (HAMD) were investigated by focusing on the unidimensional HAMD6 and MADRS6. Effect sizes were calculated and compared for two dosages of escitalopram (10 mg and 20 mg daily) and between each of these two dosages and 40 mg citalopram daily. The results showed that the three depression scales MADRS6, MADRS10 and HAMD6 were psychometrically acceptable (coefficient of homogeneity of 0.40 or higher). In the severely depressed patients (MADRS10> or =30) a rather clear dose-response relationship for escitalopram was seen on all three scales after 6 and 8 wk of therapy. Thus, the effect size for 10 mg escitalopram ranged from 0.28 to 0.38 while the effect sizes for 20 mg escitalopram ranged from 0.57 to 0.77. This difference was statistically significant (p<0.01). The effect size for 40 mg citalopram ranged from 0.36 to 0.47, which is within the range found for 40 mg citalopram in our previous dose-response analysis of citalopram after 6 wk of therapy. The numerically largest difference between 20 mg escitalopram and 40 mg citalopram was seen after 8 wk of therapy for MADRS10 (effect size 0.71 vs. 0.37). An item analysis identified 'suicidal thoughts' to be the most discriminating item in this respect. These results for the severely depressed patients were confirmed by the patients self-reported quality of life evaluation. When all included patients were analysed, however, no clear dose-response relationship was seen. In conclusion, a dose-response relationship for escitalopram was seen in the severely depressed patients on all outcome scales after 6

  11. Toxicological Evaluation of Fusarium verticillioides Culture Material Nixtamalized in the Presence and Absence of Corn Matrix

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cooking-steeping corn in alkaline water (nixtamalization) reduces the amount of detectable fumonisin B1 (FB1) in masa and tortilla products. However, reductions might be overestimated if FB1 reacts with the corn matrix to form undetectable reaction products. The purpose of this study was to investig...

  12. Illustrative case using the RISK21 roadmap and matrix: prioritization for evaluation of chemicals found in drinking water

    PubMed Central

    Wolf, Douglas C.; Bachman, Ammie; Barrett, Gordon; Bellin, Cheryl; Goodman, Jay I.; Jensen, Elke; Moretto, Angelo; McMullin, Tami; Pastoor, Timothy P.; Schoeny, Rita; Slezak, Brian; Wend, Korinna; Embry, Michelle R.

    2016-01-01

    ABSTRACT The HESI-led RISK21 effort has developed a framework supporting the use of twenty-first century technology in obtaining and using information for chemical risk assessment. This framework represents a problem formulation-based, exposure-driven, tiered data acquisition approach that leads to an informed decision on human health safety to be made when sufficient evidence is available. It provides a transparent and consistent approach to evaluate information in order to maximize the ability of assessments to inform decisions and to optimize the use of resources. To demonstrate the application of the framework’s roadmap and matrix, this case study evaluates a large number of chemicals that could be present in drinking water. The focus is to prioritize which of these should be considered for human health risk as individual contaminants. The example evaluates 20 potential drinking water contaminants, using the tiered RISK21 approach in combination with graphical representation of information at each step, using the RISK21 matrix. Utilizing the framework, 11 of the 20 chemicals were assigned low priority based on available exposure data alone, which demonstrated that exposure was extremely low. The remaining nine chemicals were further evaluated, using refined estimates of toxicity based on readily available data, with three deemed high priority for further evaluation. In the present case study, it was determined that the greatest value of additional information would be from improved exposure models and not from additional hazard characterization. PMID:26451723

  13. Illustrative case using the RISK21 roadmap and matrix: prioritization for evaluation of chemicals found in drinking water.

    PubMed

    Wolf, Douglas C; Bachman, Ammie; Barrett, Gordon; Bellin, Cheryl; Goodman, Jay I; Jensen, Elke; Moretto, Angelo; McMullin, Tami; Pastoor, Timothy P; Schoeny, Rita; Slezak, Brian; Wend, Korinna; Embry, Michelle R

    2016-01-01

    The HESI-led RISK21 effort has developed a framework supporting the use of twenty-first century technology in obtaining and using information for chemical risk assessment. This framework represents a problem formulation-based, exposure-driven, tiered data acquisition approach that leads to an informed decision on human health safety to be made when sufficient evidence is available. It provides a transparent and consistent approach to evaluate information in order to maximize the ability of assessments to inform decisions and to optimize the use of resources. To demonstrate the application of the framework's roadmap and matrix, this case study evaluates a large number of chemicals that could be present in drinking water. The focus is to prioritize which of these should be considered for human health risk as individual contaminants. The example evaluates 20 potential drinking water contaminants, using the tiered RISK21 approach in combination with graphical representation of information at each step, using the RISK21 matrix. Utilizing the framework, 11 of the 20 chemicals were assigned low priority based on available exposure data alone, which demonstrated that exposure was extremely low. The remaining nine chemicals were further evaluated, using refined estimates of toxicity based on readily available data, with three deemed high priority for further evaluation. In the present case study, it was determined that the greatest value of additional information would be from improved exposure models and not from additional hazard characterization.

  14. The Revisited Classification of GN in SLE at 10 Years: Time to Re-Evaluate Histopathologic Lesions.

    PubMed

    Wilhelmus, Suzanne; Alpers, Charles E; Cook, H Terence; Ferrario, Franco; Fogo, Agnes B; Haas, Mark; Joh, Kensuke; Noël, Laure-Hélène; Seshan, Surya V; Bruijn, Jan A; Bajema, Ingeborg M

    2015-12-01

    Over 10 years have passed since the latest revision of the histopathologic classification of lupus nephritis. This revision was a significant improvement compared with the previous version, mainly because of clearer and more concise definitions and the elimination of mixed subclasses. Despite these improvements, there are still some difficulties in the classification for lupus nephritis, many of which are in the definitions provided. In this review, we focus on the difficulties surrounding the evaluation of classes III and IV lesions, particularly the definitions of endocapillary and extracapillary proliferation, the use of the terms endocapillary proliferation and hypercellularity, the clinical relevance of segmental and global subdivision in class IV, and the value of distinguishing lesions that indicate activity and chronicity. Vascular and tubulointerstitial lesions are also discussed. Furthermore, we give an overview of the history of the classification to provide background on the origin and development of the definitions in lupus nephritis. The issues raised in this review as well as the suggestions for improvements may assist with a revision of the lupus nephritis classification in the near future.

  15. Anodic Polarization Curves Revisited

    ERIC Educational Resources Information Center

    Liu, Yue; Drew, Michael G. B.; Liu, Ying; Liu, Lin

    2013-01-01

    An experiment published in this "Journal" has been revisited and it is found that the curve pattern of the anodic polarization curve for iron repeats itself successively when the potential scan is repeated. It is surprising that this observation has not been reported previously in the literature because it immediately brings into…

  16. A Hydrostatic Paradox Revisited

    ERIC Educational Resources Information Center

    Ganci, Salvatore

    2012-01-01

    This paper revisits a well-known hydrostatic paradox, observed when turning upside down a glass partially filled with water and covered with a sheet of light material. The phenomenon is studied in its most general form by including the mass of the cover. A historical survey of this experiment shows that a common misunderstanding of the phenomenon…

  17. Parametric Resonance Revisited

    NASA Astrophysics Data System (ADS)

    van den Broeck, C.; Bena, I.

    The phenomenon of parametric resonance is revisited. Several physical examples are reviewed and an exactly solvable model is discussed. A mean field theory is presented for globally coupled parametric oscillators with randomly distributed phases. A new type of collective instability appears, which is similar in nature to that of noise induced phase transitions.

  18. Concept Image Revisited

    ERIC Educational Resources Information Center

    Bingolbali, Erhan; Monaghan, John

    2008-01-01

    Concept image and concept definition is an important construct in mathematics education. Its use, however, has been limited to cognitive studies. This article revisits concept image in the context of research on undergraduate students' understanding of the derivative which regards the context of learning as paramount. The literature, mainly on…

  19. Revisiting Bioaccumulation Criteria

    EPA Science Inventory

    The objective of workgroup 5 was to revisit the B(ioaccumulation) criteria that are currently being used to identify POPs under the Stockholm Convention and PBTs under CEPA, TSCA, REACh and other programs. Despite the lack of a recognized definition for a B substance, we defined ...

  20. The Linguistic Repertoire Revisited

    ERIC Educational Resources Information Center

    Busch, Brigitta

    2012-01-01

    This article argues for the relevance of poststructuralist approaches to the notion of a linguistic repertoire and introduces the notion of language portraits as a basis for empirical study of the way in which speakers conceive and represent their heteroglossic repertoires. The first part of the article revisits Gumperz's notion of a linguistic…

  1. Colloquial Hebrew Imperatives Revisited

    ERIC Educational Resources Information Center

    Bolozky, Shmuel

    2009-01-01

    In revisiting Bolozky's [Bolozky, Shmuel, 1979. "On the new imperative in colloquial Hebrew." "Hebrew Annual Review" 3, 17-24] and Bat-El's [Bat-El, Outi, 2002. "True truncation in colloquial Hebrew imperatives." "Language" 78(4), 651-683] analyses of colloquial Hebrew imperatives, the article argues for restricting Imperative Truncation to the…

  2. Development and Clinical Evaluation of MatrixMANDIBLE Subcondylar Plates System (Synthes).

    PubMed

    Cortelazzi, Roberto; Altacera, Mario; Turco, Monica; Antonicelli, Viviana; De Benedittis, Michele

    2015-06-01

    In this article, authors report the different steps of development and clinical validation of MatrixMANDIBLE Subcondylar Plates (Synthes, Soletta, Switzerland), a specialized osteosynthesis system developed by Synthes during the past 4 years. Between 2009 and 2013, a total of 62 patients were treated for subcondylar and condylar neck fractures via a preauricular or retromandibular/transparotid approach. The MatrixMANDIBLE Subcondylar Plates System consists of a Trapezoidal Plate, a three-dimensional (3D) 4-hole 1.0-mm plate for smaller fracture areas, the Lambda Plate, a 7-hole 1.0-mm linear plate which mimics the two miniplates technique, and the Strut Plate, a 3D 1.0-mm plate with great versatility of employment. All devices satisfy the principles of a functionally stable osteosynthesis as stated by Champy et al. None of the plates broke and no macroscopic condylar displacement was noted on radiological follow-up. Clinical and functional parameters assessed at 6 months postoperative (mandibular range of motion, pain, dental occlusion) were almost restored. MatrixMANDIBLE Subcondylar Plates System (Synthes) has proved to provide sufficient mechanical stiffness and anatomically accurate fracture reduction to avoid major postoperative drawbacks of subcondylar and condylar neck fractures.

  3. Laser-ultrasonic evaluation of damage in unidirectional ceramic matrix composites

    SciTech Connect

    Liu, Y.M.; Mitchell, T.E.; Wadley, H.N.G.

    1996-04-01

    Ceramic matrix composites (CMCs) have attracted great attention because of their potential for high temperature structural applications. Among these materials, calcium aluminosilicate (CAS) glass ceramic and similar composites reinforced by Nicalon{trademark} SiC fiber with carbon-rich interface have been under active investigation because of their {open_quotes}notch-insensitivity{close_quotes}: stress near holes and notches can be redistributed by inelastic deformation in the form of multiple matrix cracking. Therefore, stress concentration is alleviated near these sites. Understanding the damage mechanism in these composites is very important for the development of constitutive modeling. To achieve this goal, monitoring damage initiation and accumulation in-situ are especially critical. In most of the previous work, the change of elastic modulus along loading direction was used to characterize the damage. However, the overall anisotropic damages such as fiber-matrix debonding or shear deformation were unknown. In this study, we have pursued an in-situ nondestructive laser-ultrasonic technique to assess the overall anisotropic stiffness degradation under loading. When a laser pulse is brought to sample surface, high frequency acoustic waves can be generated by thermal or ablation mechanisms depending on the incident power intensity. The propagation of the elastic waves through anisotropic media is characterized by the well-known Christoffel equation.

  4. Structural integrity, immunogenicity and biomechanical evaluation of rabbit decelluarized tracheal matrix.

    PubMed

    Sun, Fei; Pan, Shu; Shi, Hong-Can; Zhang, Fang-Biao; Zhang, Wei-Dong; Ye, Gang; Liu, Xing-Chen; Zhang, Si-Quan; Zhong, Chong-Hao; Yuan, Xiao-Long

    2015-04-01

    Decellularization techniques have been widely used as an alternative strategy to produce matrices for organ reconstruction. This study investigated the impact of a detergent-enzymatic decellularization protocol on the extracellular matrix integrity, mechanical properties, and biocompatibility of decellularized tracheal matrices from rabbits. The tracheas of New Zealand white rabbits were decellularized using a modified detergent-enzymatic method (DEM). Antigenicity, cellularity, glycosaminoglycan content, DNA content, histoarchitecture, and mechanical properties were monitored during processing. The surface ultrastructure of the matrix was examined by scanning electron microscopy (SEM). Bioengineered and control tracheas were then implanted in major histocompatibility complex-unmatched rats (xenograft) heterotopically for 7, 15, and 30 days. Structural and functional analysis was performed after transplantation. The results showed that seven cycles of decellularization removed most of the cells and eliminated antigenicity. Histological and molecular biology analysis demonstrated that most of the cellular components and nuclear material were removed. SEM analysis revealed that the decellularized matrices retained the hierarchical structure of the native trachea, and biomechanical tests showed that decellularization did not significantly influence the mechanical properties. Seven, 15 and 30 days after implantation, decreased (p < 0.01) inflammatory reactions were observed in the xenograft models for decellularized matrices compared with control tracheas. No increases in IgM or IgG content were observed in rats that received bioengineered tracheas. In conclusion, this work suggests that seven cycles of the DEM generates a bioengineered rabbit tracheal matrix that is structurally and mechanically similar to native trachea.

  5. Evaluation of the Majorana phases of a general Majorana neutrino mass matrix: Testability of hierarchical flavour models

    NASA Astrophysics Data System (ADS)

    Samanta, Rome; Chakraborty, Mainak; Ghosal, Ambar

    2016-03-01

    We evaluate the Majorana phases for a general 3 × 3 complex symmetric neutrino mass matrix on the basis of Mohapatra-Rodejohann's phase convention using the three rephasing invariant quantities I12, I13 and I23 proposed by Sarkar and Singh. We find them interesting as they allow us to evaluate each Majorana phase in a model independent way even if one eigenvalue is zero. Utilizing the solution of a general complex symmetric mass matrix for eigenvalues and mixing angles we determine the Majorana phases for both the hierarchies, normal and inverted, taking into account the constraints from neutrino oscillation global fit data as well as bound on the sum of the three light neutrino masses (Σimi) and the neutrinoless double beta decay (ββ0ν) parameter |m11 |. This methodology of finding the Majorana phases is applied thereafter in some predictive models for both the hierarchical cases (normal and inverted) to evaluate the corresponding Majorana phases and it is shown that all the sub cases presented in inverted hierarchy section can be realized in a model with texture zeros and scaling ansatz within the framework of inverse seesaw although one of the sub cases following the normal hierarchy is yet to be established. Except the case of quasi degenerate neutrinos, the methodology obtained in this work is able to evaluate the corresponding Majorana phases, given any model of neutrino masses.

  6. Revisiting the CALIOP Mineral Dust Optical Model

    NASA Astrophysics Data System (ADS)

    Winker, D. M.; Omar, A. H.; Liu, Z.

    2013-12-01

    The standard aerosol extinction retrieval applied to CALIOP observations relies heavily on a priori values of the lidar ratio (the ratio of extinction to 180-degree backscatter) for each of several aerosol types. The original CALIOP aerosol models were developed over 10 years ago, based on a combination of Aeronet retrievals, measurements from ground-based lidars, and theoretical scattering calculations. Both prior to and since the launch of CALIPSO, a number of studies using a variety of approaches have shown lidar ratios of around 40 sr for mineral dust. Ground-based Raman lidar measurements in Europe and Morroco, on the other hand, have consistently shown higher values of 50 to 60 sr. Reasons for this inconsistency have not been clearly identified, but may be due to geographical variability, mixtures of dust with fine-mode aerosol, multiple scattering effects on the CALIOP retrieval, other retrieval artifacts, or a combination of these. The simplest explanation for the difference between ground-based Raman and space-based retrievals of dust lidar ratio would be multiple scattering effects on the CALIOP signals. We have taken advantage of improvements in scattering codes and of recent field campaigns to re-evaluate the CALIOP optical model for mineral dust and to revisit multiple scattering effects. The original scattering phase functions used to predict multiple scattering were based on Dipole-Dipole Approximation (DDA) calculations of size-shape mixtures of irregular dust particles. At the time, the DDA calculations were limited to particles of less than 2 um diameter. Using current T-matrix codes, we are now able to compute scattering from particles as large as 10 um diameter. Applying T-matrix scattering calculations to spheroidal particles with size distributions consistent with those measured during the SAMUM campaign in Morroco, we find multiple scattering effects are similar to those predicted from the original DDA calculations. Thus multiple scattering

  7. Matrix thermalization

    NASA Astrophysics Data System (ADS)

    Craps, Ben; Evnin, Oleg; Nguyen, Kévin

    2017-02-01

    Matrix quantum mechanics offers an attractive environment for discussing gravitational holography, in which both sides of the holographic duality are well-defined. Similarly to higher-dimensional implementations of holography, collapsing shell solutions in the gravitational bulk correspond in this setting to thermalization processes in the dual quantum mechanical theory. We construct an explicit, fully nonlinear supergravity solution describing a generic collapsing dilaton shell, specify the holographic renormalization prescriptions necessary for computing the relevant boundary observables, and apply them to evaluating thermalizing two-point correlation functions in the dual matrix theory.

  8. Evaluating changes in matrix based, recovery-adjusted concentrations in paired data for pesticides in groundwater

    USGS Publications Warehouse

    Zimmerman, Tammy M.; Breen, Kevin J.

    2012-01-01

    Pesticide concentration data for waters from selected carbonate-rock aquifers in agricultural areas of Pennsylvania were collected in 1993–2009 for occurrence and distribution assessments. A set of 30 wells was visited once in 1993–1995 and again in 2008–2009 to assess concentration changes. The data include censored matched pairs (nondetections of a compound in one or both samples of a pair). A potentially improved approach for assessing concentration changes is presented where (i) concentrations are adjusted with models of matrix-spike recovery and (ii) area-wide temporal change is tested by use of the paired Prentice-Wilcoxon (PPW) statistical test. The PPW results for atrazine, simazine, metolachlor, prometon, and an atrazine degradate, deethylatrazine (DEA), are compared using recovery-adjusted and unadjusted concentrations. Results for adjusted compared with unadjusted concentrations in 2008–2009 compared with 1993–1995 were similar for atrazine and simazine (significant decrease; 95% confidence level) and metolachlor (no change) but differed for DEA (adjusted, decrease; unadjusted, increase) and prometon (adjusted, decrease; unadjusted, no change). The PPW results were different on recovery-adjusted compared with unadjusted concentrations. Not accounting for variability in recovery can mask a true change, misidentify a change when no true change exists, or assign a direction opposite of the true change in concentration that resulted from matrix influences on extraction and laboratory method performance. However, matrix-based models of recovery derived from a laboratory performance dataset from multiple studies for national assessment, as used herein, rather than time- and study-specific recoveries may introduce uncertainty in recovery adjustments for individual samples that should be considered in assessing change.

  9. Evaluation of bone matrix gelatin/fibrin glue and chitosan/gelatin composite scaffolds for cartilage tissue engineering.

    PubMed

    Wang, Z H; Zhang, J; Zhang, Q; Gao, Y; Yan, J; Zhao, X Y; Yang, Y Y; Kong, D M; Zhao, J; Shi, Y X; Li, X L

    2016-07-15

    This study was designed to evaluate bone matrix gelatin (BMG)/fibrin glue and chitosan/gelatin composite scaffolds for cartilage tissue engineering. Chondrocytes were isolated from costal cartilage of Sprague-Dawley rats and seeded on BMG/fibrin glue or chitosan/gelatin composite scaffolds. After different in vitro culture durations, the scaffolds were subjected to hematoxylin and eosin, Masson's trichrome, and toluidine blue staining, anti-collagen II and anti-aggrecan immunohistochemistry, and scanning electronic microscopy (SEM) analysis. After 2 weeks of culture, chondrocytes were distributed evenly on the surfaces of both scaffolds. Cell numbers and the presence of extracellular matrix components were markedly increased after 8 weeks of culture, and to a greater extent on the chitosan/gelatin scaffold. The BMG/fibrin glue scaffold showed signs of degradation after 8 weeks. Immunofluorescence analysis confirmed higher levels of collagen II and aggrecan using the chitosan/gelatin scaffold. SEM revealed that the majority of cells on the surface of the BMG/fibrin glue scaffold demonstrated a round morphology, while those in the chitosan/gelatin group had a spindle-like shape, with pseudopodia. Chitosan/gelatin scaffolds appear to be superior to BMG/ fibrin glue constructs in supporting chondrocyte attachment, proliferation, and biosynthesis of cartilaginous matrix components.

  10. FDTD and transfer matrix methods for evaluating the performance of photonic crystal based microcavities for exciton-polaritons

    NASA Astrophysics Data System (ADS)

    Liu, Yi-Cheng; Byrnes, Tim

    2016-11-01

    We investigate alternative microcavity structures for exciton-polaritons consisting of photonic crystals instead of distributed Bragg reflectors. Finite-difference time-domain simulations and scattering transfer matrix methods are used to evaluate the cavity performance. The results are compared with conventional distributed Bragg reflectors. We find that in terms of the photon lifetime, the photonic crystal based microcavities are competitive, with typical lifetimes in the region of ∼20 ps being achieved. The photonic crystal microcavities have the advantage that they are compact and are frequency adjustable, showing that they are viable to investigate exciton-polariton condensation physics.

  11. R-Matrix Evaluation of Cl Neutron Cross Sections up to 1.2 MeV

    SciTech Connect

    Sayer, R.O.

    2003-03-27

    We have performed an evaluation of {sup 35}Cl, {sup 37}Cl, and {sup nat}Cl neutron cross sections in the resolved resonance region with the multilevel Reich-Moore R-matrix formalism. Resonance analyses were carried out with the computer code SAMMY, which utilizes Bayes' method, a generalized least squares technique. A recent modification of SAMMY enabled us to calculate charged particle penetrabilities for the proton exit channel. Our resonance parameter representation describes the data much better than does ENDF/B-VI, and it should lead to improved criticality safety calculations for systems where Cl is present.

  12. In vivo evaluation of matrix metalloproteinase responsive silk-elastinlike protein polymers for cancer gene therapy.

    PubMed

    Price, Robert; Poursaid, Azadeh; Cappello, Joseph; Ghandehari, Hamidreza

    2015-09-10

    Silk-elastinlike protein polymers (SELPs) have been effectively used as controlled release matrices for the delivery of viruses for cancer gene therapy in preclinical models. However, the degradability of these polymers needs to be tuned for improved localized intratumoral gene delivery. Using recombinant techniques, systematic modifications in distinct regions of the polymer backbone, namely, within the elastin blocks, silk blocks, and adjacent to silk and elastin blocks, have been made to impart sensitivity to specific matrix metalloproteinases (MMPs) known to be overexpressed in the tumor environment. In this report we investigated the structure-function relationship of MMP-responsive SELPs for viral mediated gene therapy of head and neck cancer. These polymers showed significant degradation in vitro in the presence of MMPs. Their degradation rate was a function of the location of the MMP-responsive sequence in the polymer backbone when in hydrogel form. Treatment efficacy of the adenoviral vectors released from the MMP responsive SELP analogs in a xenograft mouse model of head and neck squamous cell carcinoma (HNSCC) was shown to be polymer structure dependent. These results demonstrate the tunable nature of MMP-responsive SELPs for localized matrix-mediated gene delivery.

  13. An evaluation of fiber-reinforced titanium matrix composites for advanced high-temperature aerospace applications

    SciTech Connect

    Larsen, J.M.; Russ, S.M.; Jones, J.W.

    1995-12-01

    The current capabilities of continuous silicon-carbide fiber-reinforced titanium matrix composites (TMCs) are reviewed with respect to application needs and compared to the capabilities of conventional high-temperature monolithic alloys and aluminides. In particular, the properties of a first-generation titanium aluminide composite, SCS-6/Ti-24Al-11Nb, and a second-generation metastable beta alloy composite, SCS-6/TIMETAL 21S, are compared with the nickel-base superalloy IN100, the high-temperature titanium alloy Ti-1100, and a relatively new titanium aluminide alloy. Emphasis is given to life-limiting cyclic and monotonic properties and to the influence of time-dependent deformation and environmental effects on these properties. The composite materials offer a wide range of performance capabilities, depending on laminate architecture. In many instances, unidirectional composites exhibit outstanding properties, although the same materials loaded transverse to the fiber direction typically exhibit very poor properties, primarily due to the weak fiber/matrix interface. Depending on the specific mechanical property under consideration, composite cross-ply laminates often show no improvement over the capability of conventional monolithic materials. Thus, it is essential that these composite materials be tailored to achieve a balance of properties suitable to the specific application needs if these materials are to be attractive candidates to replace more conventional materials.

  14. Evaluation of anisotropic chitosan hydrogels using analytical Mueller matrix method and scanned laser pico-projector.

    PubMed

    Huang, Chih-Ling; Chuang, Chin-Ho; Lo, Yu-Lung

    2013-07-25

    Chitosan has excellent biodegradable, biocompatible and bio-absorbable properties and has been found increasing use in the biomedical field in recent decades. The linear birefringence (LB), linear diattenuation (LD), circular birefringence (CB), circular diattenuation (CD), and depolarization properties of chitosan hydrogel films crosslinked in citrate acid buffer solution (CBS) are extracted using an analytical Mueller matrix method. It is shown that the optical phase retardance property of the hydrogel films provides a reliable indication of both the chitosan concentration of the film and the pH value of the CBS crosslinking environment. In addition, chitosan hydrogel suspension with low-concentration crosslinked in CBS environments with various pH values are studied by the speckle contrast of the projected images obtained when illuminating the suspension with a scanned laser pico-projector (SLPP). It is found that for the samples crosslinked in an acidic environment, the speckle contrast decreases with an increasing pH value. By contrast, for the samples crosslinked in an alkaline CBS environment, the speckle contrast increases as the pH value increases. It is concluded that both the phase retardance and the speckle contrast enable the pH value of the CBS crosslinking solution to be reliably determined. However, of the two methods, the SLPP method yields improved measurement sensitivity. Overall, the results presented in this study show that the analytical Mueller matrix method and SLPP method provide an effective means of characterizing the optical properties, concentration and crosslinking environment of chitosan hydrogel films and suspensions.

  15. A theoretical approach to evaluate the release rate of acetaminophen from erosive wax matrix dosage forms.

    PubMed

    Agata, Yasuyoshi; Iwao, Yasunori; Shiino, Kai; Miyagishima, Atsuo; Itai, Shigeru

    2011-07-29

    To predict drug dissolution and understand the mechanisms of drug release from wax matrix dosage forms containing glyceryl monostearate (GM; a wax base), aminoalkyl methacrylate copolymer E (AMCE; a pH-dependent functional polymer), and acetaminophen (APAP; a model drug), we tried to derive a novel mathematical model with respect to erosion and diffusion theory. Our model exhibited good agreement with the whole set of experimentally obtained values pertaining to APAP release at pH 4.0 and pH 6.5. In addition, this model revealed that the eroding speed of wax matrices was strongly influenced by the loading content of AMCE, but not that of APAP, and that the diffusion coefficient increased as APAP loading decreased and AMCE loading increased, thus directly defining the physicochemical properties of erosion and diffusion. Therefore, this model might prove a useful equation for the precise prediction of dissolution and for understanding the mechanisms of drug release from wax matrix dosage forms.

  16. Histopathological evaluation of the effects of variable extraoral dry times and enamel matrix proteins (enamel matrix derivatives) application on replanted dogs' teeth.

    PubMed

    Barbizam, Joao V B; Massarwa, Rasha; da Silva, Lea Assed Bezerra; da Silva, Raquel Assed Bezerra; Nelson-Filho, Paulo; Consolaro, Alberto; Cohenca, Nestor

    2015-02-01

    The extra-alveolar dry period and storage medium in which the tooth was kept prior to replantation remain the critical factors affecting the survival and regeneration of the damaged periodontium. When the replantation is delayed, replacement root resorption is the most common complication following replantation of an avulsed tooth. The aim of this histological study was to evaluate the periodontal healing of replanted dogs' teeth after 20 min (short) and 60 min (long) extraoral dry time with and without the application of enamel matrix proteins. Eighty mature premolar roots (40 teeth) maxillary and mandibular premolars were extracted, the root canals were accessed, instrumented, and filled using a lateral condensation technique, and the access cavity was restored with amalgam. Each root was randomly assigned to one of experimental groups: Groups I and II: Roots were replanted after an extraoral dry time of 20 min. In group II, Emdogain(®) (Biora, Malmo, Sweden) was applied directly to the external root surface with complete coverage. Groups III and IV: Roots were replanted after an extraoral dry time of 60 min. In group IV, Emdogain(®) was applied to the whole external root surface before replantation. Roots that replanted within a total extraoral dry time of 10 min were used as negative controls, while those replanted after 90 min of extraoral dry time were assigned as positive controls. After 4 months, the dogs were euthanized, and the maxillary and mandibular processes were processed for histology and microscopically evaluated. Statistical analysis showed no significant differences (P = 0.1075) among the experimental groups. The results of this study show that 20 min of extraoral dry time is as detrimental to the PDL cells as 60 or 90 min of extraoral dry time, with avulsed dogs' teeth, even when replanted with an inductive material such as EMD. This study provides strong evidence in relation to the threshold of the extraoral dry time of avulsed teeth

  17. Evaluation of higher order PMD effects using Jones matrix analytical models: a comparative study

    NASA Astrophysics Data System (ADS)

    Ferreira, M. F.

    2006-04-01

    A comparative study among the Jones matrix analytical models with high-order PMD is presented. The models that make use of an exponential expansion arrested up to second order or consider the dispersion vector as a Taylor series expansion do not give good results in the approximation of high-order PMD effects, because of the nonlimited behavior with respect to frequency of the modulus of their dispersion vectors. On the other hand, the analytical model which describes the dispersion vector as rotating on a circumference in the Stokes space is found to be the most accurate. Moreover, it can be used to obtain an analytical expression of the pulse broadening, which is often chosen as a quality-system parameter.

  18. Evaluating cell matrix mechanics using an integrated nonlinear optical tweezer-confocal imaging system

    NASA Astrophysics Data System (ADS)

    Peng, Berney; Alonzo, Carlo A. C.; Xia, Lawrence; Speroni, Lucia; Georgakoudi, Irene; Soto, Ana M.; Sonnenschein, Carlos; Cronin-Golomb, Mark

    2013-09-01

    Biomechanics plays a central role in breast epithelial morphogenesis. In this study we have used 3D cultures in which normal breast epithelial cells are able to organize into rounded acini and tubular ducts, the main structures found in the breast tissue. We have identified fiber organization as a main determinant of ductal organization. While bulk rheological properties of the matrix seem to play a negligible role in determining the proportion of acini versus ducts, local changes may be pivotal in shape determination. As such, the ability to make microscale rheology measurements coupled with simultaneous optical imaging in 3D cultures can be critical to assess the biomechanical factors underlying epithelial morphogenesis. This paper describes the inclusion of optical tweezers based microrheology in a microscope that had been designed for nonlinear optical imaging of collagen networks in ECM. We propose two microrheology methods and show preliminary results using a gelatin hydrogel and collagen/Matrigel 3D cultures containing mammary gland epithelial cells.

  19. Evaluating Learning in the 21st Century: A Digital Age Learning Matrix

    ERIC Educational Resources Information Center

    Starkey, Louise

    2011-01-01

    If the purpose of secondary schooling is to educate the upcoming generation to become active participants in society, evaluation of teaching and learning in the information-rich digital age should be underpinned by relevant theories and models. This article describes an evaluation tool developed using emerging ideas about knowledge creation and…

  20. Revisiting Dialogues and Monologues

    ERIC Educational Resources Information Center

    Kvernbekk, Tone

    2012-01-01

    In educational discourse dialogue tends to be viewed as being (morally) superior to monologue. When we look at them as basic forms of communication, we find that dialogue is a two-way, one-to-one form and monologue is a one-way, one-to-many form. In this paper I revisit the alleged (moral) superiority of dialogue. First, I problematize certain…

  1. Clinical ethics revisited

    PubMed Central

    Singer, Peter A; Pellegrino, Edmund D; Siegler, Mark

    2001-01-01

    A decade ago, we reviewed the field of clinical ethics; assessed its progress in research, education, and ethics committees and consultation; and made predictions about the future of the field. In this article, we revisit clinical ethics to examine our earlier observations, highlight key developments, and discuss remaining challenges for clinical ethics, including the need to develop a global perspective on clinical ethics problems. PMID:11346456

  2. Mountain Rivers Revisited

    NASA Astrophysics Data System (ADS)

    Schultz, Colin

    2011-12-01

    Published in 2000, the original Mountain Rivers was written to provide a concise summary of the scientific understanding of the distinct subset of rivers that gave the book its name. Spurred by developments in the field in the past decade, the book's author, Ellen Wohl, produced Mountain Rivers Revisited, an updated edition aimed at graduate students and professional researchers. In this interview, Eos talks to Wohl about steep channels, climate change, and opportunities for future research.

  3. Evaluation of diclofenac sodium sustained release matrix pellets: impact of polyethylene glycols molecular weight.

    PubMed

    Ibrahim, A; Shazly, A

    2014-01-01

    Sustained release matrix pellets loaded with 5% w/w diclofenac sodium (DS) were prepared using extrusion/spheronization technique. Different polyethylene glycols (PEGs) of different molecular weight, namely PEG 2000, PEG 4000 and PEG 6000, were mixed with avicel PH 101 in different weight ratios to manufacture the pellet formulations and water was used as a binder. Mix torque rheometer was used to characterize the pellets' wet mass. Also, the prepared pellets were characterized for their particle sizes, DS content, shape and morphology as well as the in vitro drug release. The results showed increasing PEG weight ratio resulted in a reduction of wet mass torque as well as binder ratio, especially at PEG high weight ratios (30% and 50%) and the extent of lowering wet mass peak torque was inversely proportional to PEG molecular weight. The manufactured pellets exhibited size range of 993 μm to 1085 μm with small span values. The drug release from pellets was governed by the molecular weight of PEG used, since increasing PEG molecular weight resulted in slowing the drug release rate from pellets, but increasing its level resulted in enhancing release rate. This was attributed to increasing pellet wet mass peak torque by increasing PEG molecular weight and lowering it by increasing PEG level. The prepared pellets showed non-Fickian or anomalous drug release or the coupled diffusion/polymer relaxation.

  4. EVALUATION OF DICLOFENAC SODIUM SUSTAINED RELEASE MATRIX PELLETS: IMPACT OF POLYETHYLENE GLYCOLS MOLECULAR WEIGHT.

    PubMed

    Ibrahim, Mohamed A; Shazly, Gamal A

    2015-01-01

    Sustained release matrix pellets loaded with 5% w/w diclofenac sodium (DS) were prepared using extrusion/spheronization technique. Different polyethylene glycols (PEGs) of different molecular weight, namely PEG 2000, PEG 4000 and PEG 6000 were mixed with avicel PH 101® in different weight ratios to manufacture the pellet formulations and water was used as a binder. Mix torque rheomter was used to characterize the pellets' wet mass. Also, the prepared pellets were characterized for their particle sizes, DS content, shape and morphology as well as the in vitro drug release. The results showed that increasing PEG weight ratio resulted in a reduction of wet mass torque as well as binder ratio, especially at PEG high weight ratios (30% and 50%) and the extent of lowering wet mass peak torque was inversely proportional to PEG molecular weight. The manufactured pellets exhibited size range of 993 to 1085 µm with small span values. The drug release from pellets was governed by the molecular weight of PEG used, since increasing PEG molecular weight resulted in slowing the drug release rate from pellets, but increasing its level resulted in enhancing release rate. This was attributed to increasing pellet wet mass peak torque by increasing PEG molecular weight and lowering it by increasing PEG level. The prepared pellets showed non-Fickian or anomalous drug release or the coupled diffusion/polymer relaxation.

  5. Evaluation of enteric matrix microspheres prepared by emulsion-solvent evaporation using scanning electron microscopy.

    PubMed

    Obeidat, W M; Price, J C

    2004-02-01

    Theophylline microspheres were prepared by the emulsion-solvent evaporation method using cellulose acetate butyrate (CAB381-20) and mixtures of CAB381-20(R) and cellulose acetate phthalate. The physical state of the drug, polymers and microspheres surfaces were determined using scanning electron microscopy. For those microspheres prepared using mixtures of CAB381-20 and cellulose acetate phthalate, scanning electron micrographs were taken before dissolution and also at different stages of dissolution (in SGF, pH 1.2 and in simulated intestinal fluid, pH 7.5). Micrographs were taken of the outside surfaces of the microspheres and of the cleaved microspheres showing their interiors (core). Drug crystals were observed on or near the surface of microspheres prepared from the polymer mixtures, while no drug particles or crystals were seen on the surfaces of microspheres prepared solely from CAB381-20. An acid wash for less than 2 min was capable of extracting all drug on the surface of the microspheres prepared from a mixture of CAB381-20 and cellulose acetate phthalate. The absence of drug crystals on the surface of CAB381-20 microspheres is believed to prevent initial drug release and create a lag time in release profiles. Results suggest that in both microsphere formulations, a layer of drug-free polymer is formed outside the core matrix and is believed to be responsible for the near zero-order release profiles.

  6. Evaluation extracellular matrix-chitosan composite films for wound healing application.

    PubMed

    Asthana, Somya; Goyal, Priyanka; Dhar, Rik; K, Uvanesh; Pampanaboina, Narendra B; Christakiran, Joseph; Sagiri, S S; Khanna, Manoj; Samal, Ajit; Banerjee, Indranil; Pal, Kunal; Pramanik, Krishna; Ray, Sirsendu Sekhar

    2015-08-01

    The present study describes the preparation of extracellular matrix (ECM; from porcine omentum) based chitosan composite films for wound dressing applications. The films were prepared by varying the ECM content, whereas, the amount of chitosan was kept constant. The interactions amongst the components of the films were analyzed by FTIR and XRD studies. The films were thoroughly characterized for surface hydrophilicity, moisture retention capability, water vapor permeability, mechanical and biocompatibility. FTIR study indicated that both chitosan and ECM were present in their native form and did not lose their activity. XRD analysis suggested composition dependent change in the crystallinity of the films. The mechanical properties suggested that the composite films had sufficient properties to be used for wound dressing applications. An increase in the ECM content resulted in better hydrophilicity of the films and hence better the moisture retention capacity and retardant water vapor transmission rate property of the composite films. The films were found to be biocompatible to both blood and adipose tissue derived stem cells. In gist, the prepared films may be explored as wound dressing materials.

  7. Evaluation of Microcracking in Two Carbon-Fiber/Epoxy-Matrix Composite Cryogenic Tanks

    NASA Technical Reports Server (NTRS)

    Hodge, A. J.

    2001-01-01

    Two graphite/epoxy cryogenic pressure vessels were evaluated for microcracking. The X-33 LH2 tank lobe skins were extensively examined for microcracks. Specimens were removed from the inner skin of the X-33 tank for tensile testing. The data obtained from these tests were used to model expected microcrack density as a function of stress. Additionally, the laminate used in the Marshall Space Flight Center (MSFC) Composite Conformal, Cryogenic, Common Bulkhead, Aerogel-Insulated Tank (CBAT) was evaluated. Testing was performed in an attempt to predict potential microcracking during testing of the CBAT.

  8. R-Matrix Evaluation of 16O Neutron Cross Sections up to 6.3 MeV

    SciTech Connect

    Sayer, R.O.

    2000-08-21

    In this paper we describe an evaluation of {sup 16}O neutron cross sections in the resolved resonance region with the multilevel Reich-Moore R-matrix formalism. Resonance analyses were performed with the computer code SAMMY [LA98] which utilizes Bayes method, a generalized least squares technique. Over the years the nuclear community has developed a collection of evaluated nuclear data for applications in thermal, fast reactor, and fusion systems. However, typical neutron spectra in criticality safety applications are different from the spectra relevant to thermal, fast reactor, and fusion systems. In fact, the neutron spectra important for these non-reactor systems appear to peak in the epithermal energy range. Nuclear data play a major role in the calculation of the criticality safety margins for these systems. A thorough examination of how the present collection of nuclear data evaluations behaves in criticality safety calculations is needed. Many older evaluations will probably need to be revised, and new evaluations will be needed. Oxygen is an important element in criticality safety applications where oxides are present in significant abundance. The existing ENDF/B-VI.5 evaluation is expressed in terms of point-wise cross sections derived from the analysis of G. Hale [HA91]. Unfortunately such an evaluation is not directly useful for resonance analysis of data from samples in which oxygen is combined with other elements; for that purpose, Reich-Moore resonance parameters are needed. This paper addresses the task of providing those parameters. In the following sections we discuss the data, resonance analysis procedure, and results.

  9. Evaluation of Matrix Metalloproteinases, Cytokines and Their Potential Role in the Development of Ovarian Cancer

    PubMed Central

    Rasool, Mahmood; Malik, Arif; Basit Ashraf, Muhammad Abdul; Parveen, Gulshan; Iqbal, Shazia; Ali, Irfan; Qazi, Mahmood Husain; Asif, Muhammad; Kamran, Kashif; Iqbal, Asim; Iram, Saima; Khan, Sami Ullah; Mustafa, Mohammad Zahid; Zaheer, Ahmad; Shaikh, Rozeena; Choudhry, Hani; Jamal, Mohammad Sarwar

    2016-01-01

    Background Ovarian cancer is the 5th most common cause of deaths in the women among gynecological tumors. There are many growing evidences that stress and other behavioral factors may affect cancer progression and patient survival. The purpose of this study is to determine the key role of matrix metalloproteinases (MMPs), and cytokines in the aggregation and progression of ovarian cancer. Methodology Stress variables (MDA, AGEs, AOPPs, NO), profile of antioxidants (SOD, Catalase, Vitamin E & A, GSH, GRx, GPx) and inflammatory biomarkers (MMP-9, MMP-2, MMP-11, IL-1α and TNF-α) were biochemically assessed from venous blood of fifty ovarian cancer patients and twenty healthy control subjects. The results of all parameters were analyzed statistically by independent sample t-test. Results The results of the study demonstrated that the levels of stress variables like MDA (3.38±1.12nmol/ml), AGEs (2.72±0.22 ng/ml), AOPPs (128.48±27.23 ng/ml) and NO (58.71±8.67 ng/ml) were increased in the patients of ovarian cancer as compared to control individuals whereas the profile of antioxidants like SOD, Catalase, Vitamin E, Vitamin A, GSH and GRx were decreased in ovarian cancer patients (0.11±0.08 μg/ml, 2.41±1.01μmol/mol of protein, 0.22±0.04 μg/ml, 45.84±9.07μg/ml, 4.88±1.18μg/ml, 5.33±1.26 μmol/ml respectively). But the level of GPx antioxidant was increased in ovarian cancer patients (6.58±0.21μmol/ml). Moreover the levels of MMP-9 (64.87±5.35 ng/ml), MMP-2 (75.87±18.82 ng/ml) and MMP-11 (63.58±8.48 ng/ml) were elevated in the patients. Similarly, the levels of various cytokines TNF-α and IL-1α were also increased in the patients of ovarian cancer (32.17±3.52 pg/ml and 7.04±0.85 pg/ml respectively). Conclusion MMPs are commonly expressed in ovarian cancer which are potential extrapolative biomarkers and have a major role in metastasis. Due to oxidative stress, different cytokines are released by tumor associated macrophages (TAMs) that result in the

  10. Isotope Inversion Experiment evaluating the suitability of calibration in surrogate matrix for quantification via LC-MS/MS-Exemplary application for a steroid multi-method.

    PubMed

    Suhr, Anna Catharina; Vogeser, Michael; Grimm, Stefanie H

    2016-05-30

    quantifying endogenous analytes. We consider it a valuable and convenient tool to evaluate the correct quantification of authentic matrix samples based on a calibration curve in surrogate matrix.

  11. Formulation and Evaluation of a Novel Matrix-Type Orally Disintegrating Ibuprofen Tablet

    PubMed Central

    Tayebi, Hoda; Mortazavi, Seyed Alireza

    2011-01-01

    Orally disintegrating tablets (ODTs) are capable of turning quickly into a liquid dosage form in contact with the saliva, thus possessing the advantages of both the solid dosage forms particularly stability and liquid dosage forms specially ease of swallowing and pre-gastric absorption of drug. The aim of this study was to prepare a novel matrix-type buccal fast disintegrating ibuprofen tablet formulation using special polymers, water soluble excipients, super-disintegrants and quickly soluble granules. For this purpose different tablet formulations of ibuprofen were prepared. The amount of ibuprofen in each formulation was 100 mg. Eight groups of formulation were prepared (A-H series), accounting for a total number of 45 formulations. Formulations prepared were examined in terms of different physicochemical tests including powder/granule flowability, appearance, thickness, uniformity of weight, hardness, friability and disintegration time. Results of formulation F22a (in series F), was found to be acceptable, making it the chosen formulation for further studies. Then, by adding various flavorants and sweeteners to this formulation, complementary series of formulations, named G and H, were prepared. Following the comparison of their taste with each other through asking 10 volunteers, the most suitable formulation regarding the taste, being formulation F22s, was chosen as the ultimate formulation. This formulation had PVP, ibuprofen and croscarmellose as the intra-granular components and xylitol and saccharin as the extra-granular ingredients. Formulation F22s was found to be acceptable in terms of physicochemical tests conducted, showing quick disintegration within the buccal cavity, appropriate hardness and rather low friability. Hence formulation F22s was selected as the final formulation. PMID:24250378

  12. Synthesis and evaluation of a novel fluorescent photoprobe for imaging matrix metalloproteinases.

    PubMed

    Faust, Andreas; Waschkau, Bianca; Waldeck, Jens; Höltke, Carsten; Breyholz, Hans-Jörg; Wagner, Stefan; Kopka, Klaus; Heindel, Walter; Schäfers, Michael; Bremer, Christoph

    2008-05-01

    The measurement of matrix metalloproteinase (MMP) activity in diseases like inflammation, oncogenesis, or atherosclerosis in vivo is highly desirable. Fine-tuned pyrimidine-2,4,6-triones (barbiturates) offer nonpeptidyl lead structures for developing imaging agents for specifically visualization of activated MMPs in vivo. The aim of this study was to modify a C-5-disubstituted barbiturate and thus design a highly affine, nonpeptidic, optical MMP inhibitor (MMPI)-ligand for imaging of activated MMPs in vivo. A convergent 10 step synthesis was developed, starting with a malonic ester and (4-bromophenoxy)benzene to generate 5-bromo-pyrimidine-2,4,6-trione as the key intermediate. To minimize the interactions between activated MMPs and the dye of the conjugate 6, a PEGylated piperazine derivative was used as a spacer and an azide as a protected amino function. After linking both building blocks, reducing the azide ( Staudinger reaction) and labeling with Cy 5.5, we obtained the nonhydroxamate MMP inhibitor 6 with high affinity (IC 50-value: 48 nM for MMP-2) measured in a fluorogenic assay using commercially available MMP-substrates and the purified enzyme. Zymography revealed an efficient blocking of enzyme activity of purified MMP-2 and MMP-9 and of MMP-containing cell supernatants (HT-1080), (A-673) using the PEGylated barbiturate 5. Fluorescence microscopy studies using a highly (A-673) and a moderate (HT-1080) MMP-2 secreting cell line showed efficient binding of the Cy 5.5 labeled tracer 6 to the MMP-2 positive cells while MMP-2 negative cells (MCF-7) did not bind. Therefore, this new barbiturate-based MMP-probe has a high affinity and specificity toward MMP-2 and -9 and is thus a promising candidate for sensitive MMP detection in vivo.

  13. Teacher Education: The Application of Fisher's LSD Matrix in the Evaluation of Preservice Teachers.

    ERIC Educational Resources Information Center

    Stolworthy, Reed L.

    The degrees of variance among three groups of evaluators relative to their assessments of the teaching competencies of preservice teacher education students were studied. Subjects included groups of 23 and 32 undergraduates who were certified to teach by the teacher preparation program at Washburn University in Topeka (Kansas) in 1987 and in 1988,…

  14. The impact of the rank of marker variance-covariance matrix in principal component evaluation for genomic selection applications.

    PubMed

    Dimauro, C; Cellesi, M; Pintus, M A; Macciotta, N P P

    2011-12-01

    In genomic selection (GS) programmes, direct genomic values (DGV) are evaluated using information provided by high-density SNP chip. Being DGV accuracy strictly dependent on SNP density, it is likely that an increase in the number of markers per chip will result in severe computational consequences. Aim of present work was to test the effectiveness of principal component analysis (PCA) carried out by chromosome in reducing the marker dimensionality for GS purposes. A simulated data set of 5700 individuals with an equal number of SNP distributed over six chromosomes was used. PCs were extracted both genome-wide (ALL) and separately by chromosome (CHR) and used to predict DGVs. In the ALL scenario, the SNP variance-covariance matrix (S) was singular, positive semi-definite and contained null information which introduces 'spuriousness' in the derived results. On the contrary, the S matrix for each chromosome (CHR scenario) had a full rank. Obtained DGV accuracies were always better for CHR than ALL. Moreover, in the latter scenario, DGV accuracies became soon unsettled as the number of animals decreases, whereas in CHR, they remain stable till 900-1000 individuals. In real applications where a 54k SNP chip is used, the largest number of markers per chromosome is approximately 2500. Thus, a number of around 3000 genotyped animals could lead to reliable results when the original SNP variables are replaced by a reduced number of PCs.

  15. Biochemical and toxicological evaluation of nano-heparins in cell functional properties, proteasome activation and expression of key matrix molecules.

    PubMed

    Piperigkou, Zoi; Karamanou, Konstantina; Afratis, Nikolaos A; Bouris, Panagiotis; Gialeli, Chrysostomi; Belmiro, Celso L R; Pavão, Mauro S G; Vynios, Dimitrios H; Tsatsakis, Aristidis M

    2016-01-05

    The glycosaminoglycan heparin and its derivatives act strongly on blood coagulation, controlling the activity of serine protease inhibitors in plasma. Nonetheless, there is accumulating evidence highlighting different anticancer activities of these molecules in numerous types of cancer. Nano-heparins may have great biological significance since they can inhibit cell proliferation and invasion as well as inhibiting proteasome activation. Moreover, they can cause alterations in the expression of major modulators of the tumor microenvironment, regulating cancer cell behavior. In the present study, we evaluated the effects of two nano-heparin formulations: one isolated from porcine intestine and the other from the sea squirt Styela plicata, on a breast cancer cell model. We determined whether these nano-heparins are able to affect cell proliferation, apoptosis and invasion, as well as proteasome activity and the expression of extracellular matrix molecules. Specifically, we observed that nano-Styela compared to nano-Mammalian analogue has higher inhibitory role on cell proliferation, invasion and proteasome activity. Moreover, nano-Styela regulates cell apoptosis, expression of inflammatory molecules, such as IL-6 and IL-8 and reduces the expression levels of extracellular matrix macromolecules, such as the proteolytic enzymes MT1-MMP, uPA and the cell surface proteoglycans syndecan-1 and -2, but not on syndecan-4. The observations reported in the present article indicate that nano-heparins and especially ascidian heparin are effective agents for heparin-induced effects in critical cancer cell functions, providing an important possibility in pharmacological targeting.

  16. Nondestructive Evaluation of Advanced Fiber Reinforced Polymer Matrix Composites: A Technology Assessment

    NASA Technical Reports Server (NTRS)

    Yolken, H. Thomas; Matzkanin, George A.

    2009-01-01

    Because of their increasing utilization in structural applications, the nondestructive evaluation (NDE) of advanced fiber reinforced polymer composites continues to receive considerable research and development attention. Due to the heterogeneous nature of composites, the form of defects is often very different from a metal and fracture mechanisms are more complex. The purpose of this report is to provide an overview and technology assessment of the current state-of-the-art with respect to NDE of advanced fiber reinforced polymer composites.

  17. Nanosized Borides and Carbides for Electroplating. Metal-Matrix Coatings: Specifications, Performance Evaluation

    NASA Astrophysics Data System (ADS)

    Galevskiy, G. V.; Rudneva, V. V.; Galevskiy, S. G.; Il'yashchenko, D. P.; Kartsev, D. S.

    2016-04-01

    This paper summarizes experience of application of nano-sized carbides and borides of titanium and chromium, silicon carbide as components of electro-depositable coating compositions based on nickel, zinc, and chromium. Basic physical and mechanical properties of the coatings are determined. Technological and economic evaluation is completed; practicability of high-cost nano-diamonds substitution for nano-sized borides and carbides is justified.

  18. The Eastern Iowa Community College District Data Collection Matrix Model: A Tool for Functional Area and Program Evaluation. AIR 1990 Annual Forum Paper.

    ERIC Educational Resources Information Center

    Coker, Dana Rosenberg; Friedel, Janice Nahra

    A matrix model for the collection, management, and utilization of data was developed at Eastern Iowa Community College District, (Davenport, Iowa) for evaluating institutional effectiveness. The model was examined in relation to various assessment instruments and the evaluation of functional areas and programs. Surveys of six different target…

  19. Quantitative polarization and flow evaluation of choroid and sclera by multifunctional Jones matrix optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Sugiyama, S.; Hong, Y.-J.; Kasaragod, D.; Makita, S.; Miura, M.; Ikuno, Y.; Yasuno, Y.

    2016-03-01

    Quantitative evaluation of optical properties of choroid and sclera are performed by multifunctional optical coherence tomography. Five normal eyes, five glaucoma eyes and one choroidal atrophy eye are examined. The refractive error was found to be correlated with choroidal birefringence, polarization uniformity, and flow in addition to scleral birefringence among normal eyes. The significant differences were observed between the normal and the glaucoma eyes, as for choroidal polarization uniformity, flow and scleral birefringence. An automatic segmentation algorithm of retinal pigment epithelium and chorioscleral interface based on multifunctional signals is also presented.

  20. Evaluation of radiotherapy and chemotherapy effects in bone matrix using X-ray microfluorescence

    NASA Astrophysics Data System (ADS)

    Andrade, C. B. V.; Salata, C.; Silva, C. M.; Ferreira-Machado, S. C.; Braz, D.; Almeida, A. P.; Nogueira, L. P.; Barroso, R. C.; deAlmeida, C. E.; Mantuano, A.; Mota, C. L.; Pickler, A.

    2014-02-01

    Premenopausal women undergoing adjuvant chemotherapy and/or radiotherapy for Breast Cancer (BC) treatment have significant bone loss. This high bone mineral density loss can lead to an increased risk of fractures. In this study, there were evaluated parameters involved in osteoporosis when rats were subjected to a chemotherapy regimen (TC) and/or irradiation (IR). Female Wistar rats were divided into 3 groups: control (G1), TC+IR (G2) and IR (G3). The animals were euthanized after 5 months at the end of treatment and their femurs were excised and dissected. Sections of 10 μm thick were used for μXRF analysis at the National Laboratory of Synchrotron Light. The uteri of these rats were collected and weighed. The obtained results showed that animals from G2 had a significant reduction (p<0.05) of uterine mass when compared to control. The qualitative analysis performed by μXRF showed that animals from G2 had iron in bone composition of the femurs. This same result was notobserved in animals from G1 and G3 groups. These results suggest that early menopause occurs and osteoporosis begins, probably because of the absence, or reduced, production of estrogen. The presence of iron in the G2 samples in indicates the process of osteoporosis, because according to literature, this ion is competitive with calcium ions.

  1. A multicenter prospective trial evaluating fetal bovine dermal graft (Xenform® Matrix) for pelvic reconstructive surgery

    PubMed Central

    2010-01-01

    Background A prospective multicenter clinical study was performed to evaluate the safety and efficacy of a bovine dermal graft (Xenform® Matrix, Boston Scientific, Natick, MA, USA) during vaginal reconstructive surgery. Methods Forty-five women with ICS stage 2 or higher pelvic organ prolapse (POP) were enrolled at 4 centers. POP-Q, pelvic floor function (PFDI-20), sexual function (PISQ-12), and patient satisfaction tools were used to assess subjects at baseline, and at 2 and 6 weeks, and 3, 6 and 12 months post surgery. The significance of symptom score changes at 6 months and 1 year were determined by the t-test for paired data. Forty-three of the 45 patients completed the 12 month study. Results The majority of the subjects had cystocele (98%) and/or rectocele (84%) defects at study entry. At 12 months, 74% of the defects had improved to a stage 0 or 1. Mean PFDI-20 scores improved by 72% (p < 0.001) at 12 months, and PISQ-12 scores were maintained during the follow-up period indicating no decline in sexual function. Three subjects experienced one serious adverse event each; one of the adverse events (constipation) was deemed by the study physician to be unrelated to Xenform®. One subject had severe pyelonephritis resulting in dialysis. This subject had a previous history of pyelonephritis, sepsis and acute renal failure. The third subject had a reported recurrent cystocele of moderate severity, possibly related to the device. No graft related erosions or pain lasting more than 30 days were reported. No subjects withdrew due to an adverse event. Conclusion This study is the first to investigate the use of Xenform® Matrix in vaginal reconstructive surgery among patients with POP. Significant improvement was maintained at 12 months utilizing both objective and subjective assessment tools, confirming the safety and efficacy of this material in vaginal surgery. Trial Registration ClinicalTrials.gov NCT01244165 PMID:21144043

  2. Property Evaluation and Damage Evolution of Environmental Barrier Coatings and Environmental Barrier Coated SiC/SiC Ceramic Matrix Composite Sub-Elements

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Halbig, Michael; Jaskowiak, Martha; Hurst, Janet; Bhatt, Ram; Fox, Dennis S.

    2014-01-01

    This paper describes recent development of environmental barrier coatings on SiC/SiC ceramic matrix composites. The creep and fatigue behavior at aggressive long-term high temperature conditions have been evaluated and highlighted. Thermal conductivity and high thermal gradient cyclic durability of environmental barrier coatings have been evaluated. The damage accumulation and complex stress-strain behavior environmental barrier coatings on SiCSiC ceramic matrix composite turbine airfoil subelements during the thermal cyclic and fatigue testing of have been also reported.

  3. Evaluation of cumulative PCB exposure estimated by a job exposure matrix versus PCB serum concentrations

    PubMed Central

    Ruder, Avima M.; Succop, Paul; Waters, Martha A.

    2015-01-01

    Although polychlorinated biphenyls (PCBs) have been banned in many countries for more than three decades, exposures to PCBs continue to be of concern due to their long half-lives and carcinogenic effects. In National Institute for Occupational Safety and Health studies, we are using semiquantitative plant-specific job exposure matrices (JEMs) to estimate historical PCB exposures for workers (n=24,865) exposed to PCBs from 1938 to 1978 at three capacitor manufacturing plants. A subcohort of these workers (n=410) employed in two of these plants had serum PCB concentrations measured at up to four times between 1976 and 1989. Our objectives were to evaluate the strength of association between an individual worker’s measured serum PCB levels and the same worker’s cumulative exposure estimated through 1977 with the (1) JEM and (2) duration of employment, and to calculate the explained variance the JEM provides for serum PCB levels using (3) simple linear regression. Consistent strong and statistically significant associations were observed between the cumulative exposures estimated with the JEM and serum PCB concentrations for all years. The strength of association between duration of employment and serum PCBs was good for highly chlorinated (Aroclor 1254/HPCB) but not less chlorinated (Aroclor 1242/LPCB) PCBs. In the simple regression models, cumulative occupational exposure estimated using the JEMs explained 14–24 % of the variance of the Aroclor 1242/LPCB and 22–39 % for Aroclor 1254/HPCB serum concentrations. We regard the cumulative exposure estimated with the JEM as a better estimate of PCB body burdens than serum concentrations quantified as Aroclor 1242/LPCB and Aroclor 1254/HPCB. PMID:23475397

  4. Moving from fast to ballistic gradient in liquid chromatography/tandem mass spectrometry pharmaceutical bioanalysis: Matrix effect and chromatographic evaluations.

    PubMed

    De Nardi, Claudio; Bonelli, Fabio

    2006-01-01

    The paper describes the steps taken by the authors to move from a fast to a ballistic gradient in routine liquid chromatography/tandem mass spectrometry (LC/MS/MS) analysis of plasma samples from pharmacokinetic (PK) profiling of new chemical entities. The reduction of column dimensions from 50 x 4.6 mm to 30 x 2.1 mm followed by optimization of chromatographic separation led to a decrease in the typical runtime from 5 (fast) to 2 min (ballistic) using an API4000 tandem mass spectrometer in Turbo Ionspray mode for detection. Three analytical standards representing typical molecular structures from our sample repository were used to spike plasma from four different species (rat, dog, human and mouse). Two different approaches were used to evaluate matrix effect: post-column infusion and comparison of the peak areas of neat standards and standards spiked after extraction into different pools of plasma; the influence of PEG400 as a typical dosing vehicle was also considered. Two different protein precipitation procedures were taken into account for sample extraction prior to injection. Peak shape, width and height, selectivity and sensitivity of the method were taken into account for chromatographic evaluation. The ballistic method was successfully cross-validated with the conventional fast gradient chromatographic assay.

  5. Targeted SPECT/CT Imaging of Matrix Metalloproteinase Activity in the Evaluation of Remodeling Tissue-Engineered Vascular Grafts Implanted in a Growing Lamb Model

    PubMed Central

    Stacy, Mitchel R.; Naito, Yuji; Maxfield, Mark W.; Kurobe, Hirotsugu; Tara, Shuhei; Chan, Chung; Rocco, Kevin A.; Shinoka, Toshiharu; Sinusas, Albert J.; Breuer, Christopher K.

    2014-01-01

    Objective(s) The clinical translation of tissue-engineered vascular grafts has been demonstrated in children. The remodeling of biodegradable, cell-seeded scaffolds to functional neovessels is partially attributed to matrix metalloproteinases. Noninvasive assessment of matrix metalloproteinase activity may indicate graft remodeling and elucidate the progression of neovessel formation. Therefore, matrix metalloproteinase activity was evaluated in grafts implanted in lambs using in vivo and ex vivo hybrid imaging. Graft growth and remodeling was quantified using in vivo X-ray computed tomography angiography. Methods Cell-seeded and unseeded scaffolds were implanted in lambs (n=5) as inferior vena cava interposition grafts. At 2 and 6 months post-implantation, in vivo angiography assessed graft morphology. In vivo and ex vivo single photon emission tomography/X-ray computed tomography imaging was performed with a radiolabeled compound targeting matrix metalloproteinase activity at 6 months. Neotissue was examined at 6 months using qualitative histologic and immunohistochemical staining and quantitative biochemical analysis. Results Seeded grafts demonstrated significant luminal and longitudinal growth from 2 to 6 months. In vivo imaging revealed subjectively higher matrix metalloproteinase activity in grafts vs. native tissue. Ex vivo imaging confirmed a quantitative increase in matrix metalloproteinase activity and demonstrated higher activity in unseeded vs. seeded grafts. Glycosaminoglycan content was increased in seeded grafts vs. unseeded grafts, without significant differences in collagen content. Conclusions Matrix metalloproteinase activity remains elevated in tissue-engineered grafts 6 months post-implantation and may indicate remodeling. Optimization of in vivo imaging to noninvasively evaluate matrix metalloproteinase activity may assist in serial assessment of vascular graft remodeling. PMID:24952823

  6. Structural Anomalies Detected in Ceramic Matrix Composites Using Combined Nondestructive Evaluation and Finite Element Analysis (NDE and FEA)

    NASA Technical Reports Server (NTRS)

    Abdul-Aziz, Ali; Baaklini, George Y.; Bhatt, Ramakrishna T.

    2003-01-01

    Most reverse engineering approaches involve imaging or digitizing an object and then creating a computerized reconstruction that can be integrated, in three dimensions, into a particular design environment. The rapid prototyping technique builds high-quality physical prototypes directly from computer-aided design files. This fundamental technique for interpreting and interacting with large data sets is being used here via Velocity2 (an integrated image-processing software, ref. 1) using computed tomography (CT) data to produce a prototype three-dimensional test specimen model for analyses. A study at the NASA Glenn Research Center proposes to use these capabilities to conduct a combined nondestructive evaluation (NDE) and finite element analysis (FEA) to screen pretest and posttest structural anomalies in structural components. A tensile specimen made of silicon nitrite (Si3N4) ceramic matrix composite was considered to evaluate structural durability and deformity. Ceramic matrix composites are being sought as candidate materials to replace nickel-base superalloys for turbine engine applications. They have the unique characteristics of being able to withstand higher operating temperatures and harsh combustion environments. In addition, their low densities relative to metals help reduce component mass (ref. 2). Detailed three-dimensional volume rendering of the tensile test specimen was successfully carried out with Velocity2 (ref. 1) using two-dimensional images that were generated via computed tomography. Subsequent, three-dimensional finite element analyses were performed, and the results obtained were compared with those predicted by NDE-based calculations and experimental tests. It was shown that Velocity2 software can be used to render a three-dimensional object from a series of CT scan images with a minimum level of complexity. The analytical results (ref. 3) show that the high-stress regions correlated well with the damage sites identified by the CT scans

  7. Preparation and In Vitro-In Vivo Evaluation of Sustained-Release Matrix Pellets of Capsaicin to Enhance the Oral Bioavailability.

    PubMed

    Zhang, Ya; Huang, Zhimin; Omari-Siaw, E; Lu, Shuang; Zhu, Yuan; Jiang, Dongmei; Wang, Miaomiao; Yu, Jiangnan; Xu, Ximing; Zhang, Weiming

    2016-04-01

    Capsaicin has multiple pharmacological activities including antioxidant, anticancer, and anti-inflammatory activities. However, its clinical application is limited due to its poor aqueous solubility, gastric irritation, and low oral bioavailability. This research was aimed at preparing sustained-release matrix pellets of capsaicin to enhance its oral bioavailability. The pellets comprised of a core of solid-dispersed capsaicin mixed with microcrystalline cellulose (MCC) and hydroxypropyl cellulose (HPMC) and subsequently coating with ethyl cellulose (EC) were obtained by using the technology of extrusion/spheronization. The physicochemical properties of the pellets were evaluated through scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and X-ray diffractometry (XRD). Besides, the in vitro release, in vivo absorption, and in vitro-in vivo correlation were also assessed. More importantly, the relative bioavailability of the sustained-release matrix pellets was studied in fasted rabbits after oral administration using free capsaicin and solid dispersion as references. The oral bioavailability of the matrix pellets and sustained-release matrix pellets of capsaicin was improved approximately 1.98-fold and 5.34-fold, respectively, compared with the free capsaicin. A good level A IVIVC (in vitro-in vivo correlation) was established between the in vitro dissolution and the in vivo absorption of sustained-release matrix pellets. All the results affirmed the remarkable improvement in the oral bioavailability of capsaicin owing to the successful preparation of its sustained-release matrix pellets.

  8. A novel gastro-floating multiparticulate system for dipyridamole (DIP) based on a porous and low-density matrix core: in vitro and in vivo evaluation.

    PubMed

    Li, Zhao; Xu, Heming; Li, Shujuan; Li, Qijun; Zhang, Wenji; Ye, Tiantian; Yang, Xinggang; Pan, Weisan

    2014-01-30

    The study was aimed to develop a novel gastro-floating multiparticulate system based on a porous and low-density matrix core with excellent floatability. The gastro-floating pellets (GFP) were composed of a porous matrix core, a drug loaded layer (DIP and HPMC), a sub-coating layer (HPMC) and a retarding layer (Eudragit(®) NE 30D). The porous matrix cores were evaluated in specific. EC was chosen as the matrix membrane for its rigidity and minimal expansion to large extent. The porous matrix core was achieved by the complete release of the bulk water soluble excipient from the EC coated beads, and mannitol was selected as the optimal water soluble excipient. SEM photomicrographs confirmed the structure of porous matrix cores. The compositions of GFP were investigated and optimized by orthogonal array design. The optimized formulation could sustain the drug release for 12h and float on the dissolution medium for at least 12h without lag time to float. The pharmacokinetic study was conducted in beagle dogs, and the relative bioavailability of the test preparation was 193.11±3.43%. In conclusion, the novel gastro-floating pellets can be developed as a promising approach for the gastro-retentive drug delivery systems.

  9. Evaluation of Matrix Effects in Multiresidue Analysis of Pesticide Residues in Vegetables and Spices by LC-MS/MS.

    PubMed

    Chawla, Suchi; Patel, Hemlatta K; Gor, Hetal N; Vaghela, Kiran M; Solanki, Priti P; Shah, Paresh G

    2017-03-16

    The study was conducted to investigate matrix interferences using QuEChERS sample preparation to understand whether thedilution of matrix and/or the grouping of commodities can eliminate the need for selective individual matrix-matched standards in LC with tandem MS (MS/MS) analysis, and whether the calibration graph based on only one matrix can be used for quantification in the other matrixes. Matrix effects (MEs) were studied by comparing the slopes of calibration curves of the matrix-matched standards (diluted with mobile phase) vis-à-vis the solvent-based standards. The present study showed that MEs were dependent on the nature of both the commodity and the analyte. Among the test matrixes, the highest variability in ME was recorded in capsicum. Most of the pesticides showed signal suppression in tomato, capsicum, and cumin matrixes. In brinjal matrix, the signal of most of the pesticides showed slight enhancement. Due to the similar nature of the MEs in tomato and capsicum, these two commodities can be grouped together. Considering analyte variability, acetamiprid, 3-hydroxy carbofuran, dichlorvos, dimethoate, and spinosyn A and D showed no significant ME (≤20%) in tomato. Very high MEs (2360.9 and 1250.8%) were observed for quizalofop-p-tefuryl and tebuconazole, respectively. To check the effect of dilution in minimizing the ME, cucumber and brinjal matrixes were diluted 10×, and calibration curves were drawn with five concentration levels. It was found that about 60% of the total analyzed pesticides showed MEs ≤20%. In cumin, MEs ranged from −5.3% for triazophos to 661% for thiacloprid. Most of the pesticides showed recoveries in the acceptable range of 70–130% with calibration curves from both matrixes. To compensate for MEs, it is suggested that (1) tomato and capsicum matrixes, which show similar trends, can be grouped together; and (2) cucumber matrix, when diluted 10×, can be used to prepare calibration curves for the

  10. Evaluation of matrix-assisted laser desorption ionization-time-of-flight mass spectrometry for species identification of nonfermenting Gram-negative bacilli.

    PubMed

    Almuzara, Marisa; Barberis, Claudia; Traglia, Germán; Famiglietti, Angela; Ramirez, Maria Soledad; Vay, Carlos

    2015-05-01

    Matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) to identify 396 Nonfermenting Gram-Negative Bacilli clinical isolates was evaluated in comparison with conventional phenotypic tests and/or molecular methods. MALDI-TOF MS identified to species level 256 isolates and to genus or complex level 112 isolates. It identified 29 genera including uncommon species.

  11. Evaluation of combined matrix-assisted laser desorption/ionization time-of-flight and matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry experiments for peptide mass fingerprinting analysis.

    PubMed

    da Silva, David; Wasselin, Thierry; Carré, Vincent; Chaimbault, Patrick; Bezdetnaya, Lina; Maunit, Benoît; Muller, Jean-François

    2011-07-15

    Peptide Mass Fingerprinting (PMF) is still of significant interest in proteomics because it allows a large number of complex samples to be rapidly screened and characterized. The main part of post-translational modifications is generally preserved. In some specific cases, PMF suffers from ambiguous or unsuccessful identification. In order to improve its reliability, a combined approach using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) and matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry (MALDI-FTICRMS) was evaluated. The study was carried out on bovine serum albumin (BSA) digest. The influence of several important parameters (the matrix, the sample preparation method, the amount of the analyte) on the MOWSE score and the protein sequence coverage were evaluated to allow the identification of specific effects. A careful investigation of the sequence coverage obtained by each kind of experiment ensured the detection of specific peptides for each experimental condition. Results highlighted that DHB-FTICRMS and DHB- or CHCA-TOFMS are the most suited combinations of experimental conditions to achieve PMF analysis. The association (convolution) of the data obtained by each of these techniques ensured a significant increase in the MOWSE score and the protein sequence coverage.

  12. Quantum duel revisited

    NASA Astrophysics Data System (ADS)

    Schmidt, Alexandre G. M.; Paiva, Milena M.

    2012-03-01

    We revisit the quantum two-person duel. In this problem, both Alice and Bob each possess a spin-1/2 particle which models dead and alive states for each player. We review the Abbott and Flitney result—now considering non-zero α1 and α2 in order to decide if it is better for Alice to shoot or not the second time—and we also consider a duel where players do not necessarily start alive. This simple assumption allows us to explore several interesting special cases, namely how a dead player can win the duel shooting just once, or how can Bob revive Alice after one shot, and the better strategy for Alice—being either alive or in a superposition of alive and dead states—fighting a dead opponent.

  13. ``Robinson's sum rule'' revisited

    NASA Astrophysics Data System (ADS)

    Orlov, Yuri F.

    2010-02-01

    This discussion revisits two articles on synchrotron radiation damping published in 1958, one by this author and Evgeny K. Tarasov [Zh. Eksp. Teor. Fiz. 34, 651 (1958)ZETFA70044-4510; Sov. Phys. JETP 34, 449 (1958)SPHJAR0038-5646], and one by Kenneth W. Robinson [Phys. Rev. 111, 373 (1958)PHRVAO0031-899X10.1103/PhysRev.111.373]. The latter is the source of what is known as “Robinson’s sum rule.” Both present the familiar rule, but with very different proofs and calculations of concrete damping decrements. Comparative analysis of these differences reveals serious flaws in Robinson’s proof and calculations.

  14. Polite Theories Revisited

    NASA Astrophysics Data System (ADS)

    Jovanović, Dejan; Barrett, Clark

    The classic method of Nelson and Oppen for combining decision procedures requires the theories to be stably-infinite. Unfortunately, some important theories do not fall into this category (e.g. the theory of bit-vectors). To remedy this problem, previous work introduced the notion of polite theories. Polite theories can be combined with any other theory using an extension of the Nelson-Oppen approach. In this paper we revisit the notion of polite theories, fixing a subtle flaw in the original definition. We give a new combination theorem which specifies the degree to which politeness is preserved when combining polite theories. We also give conditions under which politeness is preserved when instantiating theories by identifying two sorts. These results lead to a more general variant of the theorem for combining multiple polite theories.

  15. Effective string theory revisited

    NASA Astrophysics Data System (ADS)

    Dubovsky, Sergei; Flauger, Raphael; Gorbenko, Victor

    2012-09-01

    We revisit the effective field theory of long relativistic strings such as confining flux tubes in QCD. We derive the Polchinski-Strominger interaction by a calculation in static gauge. This interaction implies that a non-critical string which initially oscillates in one direction gets excited in orthogonal directions as well. In static gauge no additional term in the effective action is needed to obtain this effect. It results from a one-loop calculation using the Nambu-Goto action. Non-linearly realized Lorentz symmetry is manifest at all stages in dimensional regularization. We also explain that independent of the number of dimensions non-covariant counterterms have to be added to the action in the commonly used zeta-function regularization.

  16. Performance evaluation of nonnegative matrix factorization algorithms to estimate task-related neuronal activities from fMRI data.

    PubMed

    Ding, Xiaoyu; Lee, Jong-Hwan; Lee, Seong-Whan

    2013-04-01

    Nonnegative matrix factorization (NMF) is a blind source separation (BSS) algorithm which is based on the distinct constraint of nonnegativity of the estimated parameters as well as on the measured data. In this study, according to the potential feasibility of NMF for fMRI data, the four most popular NMF algorithms, corresponding to the following two types of (1) least-squares based update [i.e., alternating least-squares NMF (ALSNMF) and projected gradient descent NMF] and (2) multiplicative update (i.e., NMF based on Euclidean distance and NMF based on divergence cost function), were investigated by using them to estimate task-related neuronal activities. These algorithms were applied firstly to individual data from a single subject and, subsequently, to group data sets from multiple subjects. On the single-subject level, although all four algorithms detected task-related activation from simulated data, the performance of multiplicative update NMFs was significantly deteriorated when evaluated using visuomotor task fMRI data, for which they failed in estimating any task-related neuronal activities. In group-level analysis on both simulated data and real fMRI data, ALSNMF outperformed the other three algorithms. The presented findings may suggest that ALSNMF appears to be the most promising option among the tested NMF algorithms to extract task-related neuronal activities from fMRI data.

  17. Method Developed for the High-Temperature Nondestructive Evaluation of Fiber-Reinforced Silicon Carbide Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Goldsby, Jon C.

    1998-01-01

    Ceramic matrix composites have emerged as candidate materials to allow higher operating temperatures (1000 to 1400 C) in gas turbine engines. A need, therefore, exists to develop nondestructive methods to evaluate material integrity at the material operating temperature by monitoring thermal and mechanical fatigue. These methods would also have potential as quality inspection tools. The goal of this investigation at the NASA Lewis Research Center is to survey and correlate the temperature-dependent damping and stiffness of advanced ceramic composite materials with imposed thermal and stress histories that simulate in-service turbine engine conditions. A typical sample size of 100 by 4 by 2 cubic millimeters, along with the specified stiffness and density, placed the fundamental vibration frequencies between 100 and 2000 Hz. A modified Forster apparatus seemed most applicable to simultaneously measure both damping and stiffness. Testing in vacuum reduced the effects of air on the measurements. In this method, a single composite sample is vibrated at its fundamental tone; then suddenly, the mechanical excitation is removed so that the sample's motion freely decays with time. Typical results are illlustrated in this paper.

  18. Fractal analysis and Gray level co-occurrence matrix method for evaluation of reperfusion injury in kidney medulla.

    PubMed

    Pantic, Igor; Nesic, Zorica; Paunovic Pantic, Jovana; Radojević-Škodrić, Sanja; Cetkovic, Mila; Basta Jovanovic, Gordana

    2016-05-21

    Fractal analysis and Gray level co-occurrence matrix method represent two novel mathematical algorithms commonly used in medical sciences as potential parts of computer-aided diagnostic systems. In this study, we tested the ability of these methods to discriminate the kidney medullar tissue suffering from reperfusion injury, from normal tissue. A total of 320 digital micrographs of Periodic acid-Schiff (PAS) - stained kidney medulla from 16 Wistar albino mice (20 per animal), were analyzed using National Institutes of Health ImageJ software (NIH, Bethesda, MD) and its plugins. 160 micrographs were obtained from the experimental group with induced reperfusion injury, and another 160 were obtained from the controls. For each micrograph we calculated the values of fractal dimension, lacunarity, as well as five GLCM features: angular second moment, entropy, inverse difference moment, GLCM contrast, and GLCM correlation. Discriminatory value of the parameters was tested using receiver operating characteristic (ROC) analysis, by measuring the area below ROC curve. The results indicate that certain features of GLCM algorithm have excellent discriminatory ability in evaluation of damaged kidney tissue. Fractal dimension and lacunarity as parameters of fractal analysis also had a relatively good discriminatory value in differentiation of injured from the normal tissue. Both methods have potentially promising application in future design of novel techniques applicable in cell physiology, histology and pathology.

  19. Clinical evaluation of a combined regenerative technique with enamel matrix derivative, bone grafts, and guided tissue regeneration.

    PubMed

    Harris, Randall J; Harris, Laura E; Harris, Christopher R; Harris, Anne J

    2007-04-01

    The goal of this study was to evaluate the clinical changes obtained when intra-bony defects were treated with an enamel matrix derivative (EMD), a bone graft, and guided tissue regeneration. Fifty patients with a periodontal defect not associated with a furcation and with an attachment loss of at least 7.0 mm were included in this study. Full-thickness flaps were reflected, the roots were planed, EMD was applied, a demineralized freeze-dried bone allograft combined with EMD was placed, a bioabsorbable membrane was placed, and more EMD was applied. The defect areas were then sutured. At a mean of 5.3 months after treatment, there was a mean increase in recession of 0.7 mm, a mean reduction in probing depth of 5.7 mm, and a mean gain in attachment level of 5.0 mm. In this study there was more recession in smokers than in nonsmokers and in defects associated with anterior teeth. Additionally, the deeper defects (those with greater probing depths and attachment level loss) had the greatest reductions in probing depth and gains in attachment level. Based on this study, this technique proved itself to be an effective method to improve the clinical situation when treating periodontal defects not involving furcations.

  20. Application of fractal and grey level co-occurrence matrix analysis in evaluation of brain corpus callosum and cingulum architecture.

    PubMed

    Pantic, Igor; Dacic, Sanja; Brkic, Predrag; Lavrnja, Irena; Pantic, Senka; Jovanovic, Tomislav; Pekovic, Sanja

    2014-10-01

    This aim of this study was to assess the discriminatory value of fractal and grey level co-occurrence matrix (GLCM) analysis methods in standard microscopy analysis of two histologically similar brain white mass regions that have different nerve fiber orientation. A total of 160 digital micrographs of thionine-stained rat brain white mass were acquired using a Pro-MicroScan DEM-200 instrument. Eighty micrographs from the anterior corpus callosum and eighty from the anterior cingulum areas of the brain were analyzed. The micrographs were evaluated using the National Institutes of Health ImageJ software and its plugins. For each micrograph, seven parameters were calculated: angular second moment, inverse difference moment, GLCM contrast, GLCM correlation, GLCM variance, fractal dimension, and lacunarity. Using the Receiver operating characteristic analysis, the highest discriminatory value was determined for inverse difference moment (IDM) (area under the receiver operating characteristic (ROC) curve equaled 0.925, and for the criterion IDM≤0.610 the sensitivity and specificity were 82.5 and 87.5%, respectively). Most of the other parameters also showed good sensitivity and specificity. The results indicate that GLCM and fractal analysis methods, when applied together in brain histology analysis, are highly capable of discriminating white mass structures that have different axonal orientation.

  1. Evaluation of the Antimicrobial Efficacy of a Novel Rifampin/Minocycline-Coated, Noncrosslinked Porcine Acellular Dermal Matrix Compared With Uncoated Scaffolds for Soft Tissue Repair.

    PubMed

    Majumder, Arnab; Scott, Jeffrey R; Novitsky, Yuri W

    2016-10-01

    Background Despite meticulous aseptic technique and systemic antibiotics, bacterial colonization of mesh remains a critical issue in hernia repair. A novel minocycline/rifampin tyrosine-coated, noncrosslinked porcine acellular dermal matrix (XenMatrix AB) was developed to protect the device from microbial colonization for up to 7 days. The objective of this study was to evaluate the in vitro and in vivo antimicrobial efficacy of this device against clinically isolated methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli. Methods XenMatrix AB was compared with 5 existing uncoated soft tissue repair devices using in vitro methods of zone of inhibition (ZOI) and scanning electron microscopy (SEM) at 24 hours following inoculation with MRSA or E coli These devices were also evaluated at 7 days following dorsal implantation and inoculation with MRSA or E coli (60 male New Zealand white rabbits, n = 10 per group) for viable colony-forming units (CFU), abscess formation and histopathologic response, respectively. Results In vitro studies demonstrated a median ZOI of 36 mm for MRSA and 16 mm for E coli for XenMatrix AB, while all uncoated devices showed no inhibition of bacterial growth (0 mm). SEM also demonstrated no visual evidence of MRSA or E coli colonization on the surface of XenMatrix AB compared with colonization of all other uncoated devices. In vivo XenMatrix AB demonstrated complete inhibition of bacterial colonization, no abscess formation, and a reduced inflammatory response compared with uncoated devices. Conclusion We demonstrated that XenMatrix AB possesses potent in vitro and in vivo antimicrobial efficacy against clinically isolated MRSA and E coli compared with uncoated devices.

  2. Systematic evaluation of matrix effects in hydrophilic interaction chromatography versus reversed phase liquid chromatography coupled to mass spectrometry.

    PubMed

    Periat, Aurélie; Kohler, Isabelle; Thomas, Aurélien; Nicoli, Raul; Boccard, Julien; Veuthey, Jean-Luc; Schappler, Julie; Guillarme, Davy

    2016-03-25

    Reversed phase liquid chromatography (RPLC) coupled to mass spectrometry (MS) is the gold standard technique in bioanalysis. However, hydrophilic interaction chromatography (HILIC) could represent a viable alternative to RPLC for the analysis of polar and/or ionizable compounds, as it often provides higher MS sensitivity and alternative selectivity. Nevertheless, this technique can be also prone to matrix effects (ME). ME are one of the major issues in quantitative LC-MS bioanalysis. To ensure acceptable method performance (i.e., trueness and precision), a careful evaluation and minimization of ME is required. In the present study, the incidence of ME in HILIC-MS/MS and RPLC-MS/MS was compared for plasma and urine samples using two representative sets of 38 pharmaceutical compounds and 40 doping agents, respectively. The optimal generic chromatographic conditions in terms of selectivity with respect to interfering compounds were established in both chromatographic modes by testing three different stationary phases in each mode with different mobile phase pH. A second step involved the assessment of ME in RPLC and HILIC under the best generic conditions, using the post-extraction addition method. Biological samples were prepared using two different sample pre-treatments, i.e., a non-selective sample clean-up procedure (protein precipitation and simple dilution for plasma and urine samples, respectively) and a selective sample preparation, i.e., solid phase extraction for both matrices. The non-selective pretreatments led to significantly less ME in RPLC vs. HILIC conditions regardless of the matrix. On the contrary, HILIC appeared as a valuable alternative to RPLC for plasma and urine samples treated by a selective sample preparation. Indeed, in the case of selective sample preparation, the compounds influenced by ME were different in HILIC and RPLC, and lower and similar ME occurrence was generally observed in RPLC vs. HILIC for urine and plasma samples

  3. Evaluation of ethylcellulose and its pseudolatex (Surelease) in preparation of matrix pellets of theophylline using extrusion-spheronization

    PubMed Central

    Garekani, Hadi Afrasiabi; Dolatabadi, Roshanak; Akhgari, Abbas; Abbaspour, Mohammad Reza; Sadeghi, Fatemeh

    2017-01-01

    Objective(s): This study evaluates the effect of substitution of microcrystalline cellulose (MCC) with ethylcellulose (EC) on mechanical and release characteristics of theophylline pellets. Materials and Methods: The effect of addition of EC was investigated on characteristics of pellets with varying drug content prepared by extrusion-spheronization. Also the effect of type of granulating liquid (water or Surelease) was investigated on characteristics of selected pellets. The pellets were characterized for particle size (sieve analysis), mechanical strength, morphology (microscopy), thermal (DSC) and dissolution behaviors. Results: The exrtudability of the wet mass was reduced upon inclusion of EC so that complete replacement of MCC was not possible. Increase in EC percentage led to lower production yield and formation of pellets with larger diameter and slightly rough surfaces. Inclusion of EC also affected the mechanical properties of pellets but had negligible effect on drug release profile. The surface of selected pellets became smoother and their production yield increased upon the use of Surelease as granulating liquid. In addition the rate of drug release decreased to some extent when Surelease was used. Conclusion: Preparation of theophylline pellets with EC alone was not possible in process of extrusion-spheronization. Partial replacement of MCC with EC changed physicomechanical properties of pellets but hardly affected drug release. Although the use of Surelease as granulation liquid slightly decreased the rate of drug release, desirable matrix pellets with sustained drug release could not be produced. Despite this outcome however, these pellets could benefit from reduced coating thickness for drug release control. PMID:28133518

  4. Design and Evaluation of Ethyl Cellulose Based Matrix Tablets of Ibuprofen with pH Modulated Release Kinetics

    PubMed Central

    Chandran, S.; Asghar, Laila F. A.; Mantha, Neelima

    2008-01-01

    Controlled release preparations have been reported to reduce the gastro irritant and ulcerogenic effects of non steroidal antiinflammatory drugs. In the present study, an attempt was made to develop matrix tablet-based controlled release formulations of ibuprofen, using ethyl cellulose as the rate-controlling polymer. In order to prevent initial release of the drug in the acidic environment of the stomach, cellulose acetate phthalate was incorporated in the matrix in varying amounts. It was found that with increasing the proportion of ethyl cellulose in the matrix, the drug release was extended for 14-16 h. Incorporation of cellulose acetate phthalate in ethyl cellulose matrix provided very low initial release of the drug in the first 2-3 h followed by enhanced release rate in alkaline medium owing to the high solubility of cellulose acetate phthalate at basic pH which led to creation of a porous matrix. It was concluded that combination of cellulose acetate phthalate with ethyl cellulose in the matrix base can be an effective means of developing a controlled release formulation of ibuprofen with very low initial release followed with controlled release up to 14-16 h. PMID:21394255

  5. Separate Evaluation of the Kinetics of Carbide Precipitation Occurring at the Interface of Preexisting Particles and Within the Austenitic Matrix in a Microalloyed Steel

    NASA Astrophysics Data System (ADS)

    Jung, Jae-Gil; Shin, Eunjoo; Lee, Young-Kook

    2017-01-01

    The isothermal kinetics of carbide precipitation occurring at the interface of preexisting (Ti,Nb)(N,C) particles and within the deformed γ-austenite matrix were separately evaluated using a Nb-Ti-V microalloyed steel through small-angle neutron scattering and transmission electron microscopy. While the specimen was isothermally held after deformation at 1223 K (950 °C), (Nb,Ti)(C,N) particles were precipitated at the interface of coarse (Ti,Nb)(N,C) particles preexisting in the recrystallized γ matrix. This resulted in a single size distribution curve, which was converted from the measured magnetic scattering cross section. However, during isothermal holding after deformation at 1123 K (850 °C), fine (Nb,Ti,V)(C,N) particles formed mainly within the deformed γ matrix, although some of them were precipitated at the interface of preexisting coarse (Ti,Nb)(N,C) particles. Accordingly, the specimens held at 1123 K (850 °C) exhibited double size distribution curves. The separate evaluation between matrix and interface precipitation kinetics was successfully performed using the size distribution curves due to the difference in particle size according to the nucleation site. The reliability of carbide precipitation kinetics was confirmed by comparing the measured ratio between magnetic and nuclear scattering cross sections with the ratio calculated based on the measured chemical composition of precipitates.

  6. Controlled release of 5-fluorouracil or mitomycin-c from polymer matrix: Preparation by radiation polymerization and in vivo evaluation of the anticancer drug/polymer composites

    NASA Astrophysics Data System (ADS)

    Li, Ximing; Shen, Weiming; Liu, Chengjie; Nishimoto, Sei-Ichi; Kagiya, Tsutomu

    Polymer tablets containing anticancer drugs such as 5-fluorouracil (5-FU) and mitomycin-C (MMC) have been prepared to evaluate the drug-release characteristics in vitro and the effect on local control of mouse solid tumors in vivo. Radiation-induced polymerization of hydrophilic monomers (2-hydroxyethyl methacrylate and related monomers) at low temperature (-80°C) was performed to immobilize 5-FU or MMC in the polymer matrix. The drug was dispersed as microcrystallines within the polymer matrix. The rate of drug release in vitro in buffer solution (pH7.0, 37°C) increased with increase in hydrophilicity of polymer matrix. Appropriate amount of crosslinks within the polymer matrix, as formed by ethylene glycol dimethacrylate (2G) added in the polymerization system, was effective to control the rate of drug release. The drug release became faster upon the addition of increasing amount of water in the radiation-induced polymerization. The tablet consisting of drug/polymer was buried surgically near solid tumors of striate muscle sarcoma (S180) transplanted to Kunming mice and the therapeutic effect of slow releasing drugs was evaluated in vivo by reference to intraperitoneal (i.p.) injection of the corresponding drugs. The slow releasing drugs led to high chemotherapeutic gain for local control of solid tumors with remarkable reduction of toxic side effect of the drugs.

  7. Revisiting caspases in sepsis

    PubMed Central

    Aziz, M; Jacob, A; Wang, P

    2014-01-01

    Sepsis is a life-threatening illness that occurs due to an abnormal host immune network which extends through the initial widespread and overwhelming inflammation, and culminates at the late stage of immunosupression. Recently, interest has been shifted toward therapies aimed at reversing the accompanying periods of immune suppression. Studies in experimental animals and critically ill patients have demonstrated that increased apoptosis of lymphoid organs and some parenchymal tissues contributes to this immune suppression, anergy and organ dysfunction. Immediate to the discoveries of the intracellular proteases, caspases for the induction of apoptosis and inflammation, and their striking roles in sepsis have been focused elaborately in a number of original and review articles. Here we revisited the different aspects of caspases in terms of apoptosis, pyroptosis, necroptosis and inflammation and focused their links in sepsis by reviewing several recent findings. In addition, we have documented striking perspectives which not only rewrite the pathophysiology, but also modernize our understanding for developing novel therapeutics against sepsis. PMID:25412304

  8. Searle's"Dualism Revisited"

    SciTech Connect

    P., Henry

    2008-11-20

    A recent article in which John Searle claims to refute dualism is examined from a scientific perspective. John Searle begins his recent article 'Dualism Revisited' by stating his belief that the philosophical problem of consciousness has a scientific solution. He then claims to refute dualism. It is therefore appropriate to examine his arguments against dualism from a scientific perspective. Scientific physical theories contain two kinds of descriptions: (1) Descriptions of our empirical findings, expressed in an every-day language that allows us communicate to each other our sensory experiences pertaining to what we have done and what we have learned; and (2) Descriptions of a theoretical model, expressed in a mathematical language that allows us to communicate to each other certain ideas that exist in our mathematical imaginations, and that are believed to represent, within our streams of consciousness, certain aspects of reality that we deem to exist independently of their being perceived by any human observer. These two parts of our scientific description correspond to the two aspects of our general contemporary dualistic understanding of the total reality in which we are imbedded, namely the empirical-mental aspect and the theoretical-physical aspect. The duality question is whether this general dualistic understanding of ourselves should be regarded as false in some important philosophical or scientific sense.

  9. Cats protecting birds revisited.

    PubMed

    Fan, Meng; Kuang, Yang; Feng, Zhilan

    2005-09-01

    In this paper, we revisit the dynamical interaction among prey (bird), mesopredator (rat), and superpredator (cat) discussed in [Courchamp, F., Langlais, M., Sugihara, G., 1999. Cats protecting birds: modelling the mesopredator release effect. Journal of Animal Ecology 68, 282-292]. First, we develop a prey-mesopredator-superpredator (i.e., bird-rat-cat, briefly, BRC) model, where the predator's functional responses are derived based on the classical Holling's time budget arguments. Our BRC model overcomes several model construction problems in Courchamp et al. (1999), and admits richer, reasonable and realistic dynamics. We explore the possible control strategies to save or restore the bird by controlling or eliminating the rat or the cat when the bird is endangered. We establish the existence of two types of mesopredator release phenomena: severe mesopredator release, where once superpredators are suppressed, a burst of mesopredators follows which leads their shared prey to extinction; and mild mesopredator release, where the mesopredator release could assert more negative impact on the endemic prey but does not lead the endemic prey to extinction. A sharp sufficient criterion is established for the occurrence of severe mesopredator release. We also show that, in a prey-mesopredator-superpredator trophic food web, eradication of introduced superpredators such as feral domestic cats in the BRC model, is not always the best solution to protect endemic insular prey. The presence of a superpredator may have a beneficial effect in such systems.

  10. Twin Signature Schemes, Revisited

    NASA Astrophysics Data System (ADS)

    Schäge, Sven

    In this paper, we revisit the twin signature scheme by Naccache, Pointcheval and Stern from CCS 2001 that is secure under the Strong RSA (SRSA) assumption and improve its efficiency in several ways. First, we present a new twin signature scheme that is based on the Strong Diffie-Hellman (SDH) assumption in bilinear groups and allows for very short signatures and key material. A big advantage of this scheme is that, in contrast to the original scheme, it does not require a computationally expensive function for mapping messages to primes. We prove this new scheme secure under adaptive chosen message attacks. Second, we present a modification that allows to significantly increase efficiency when signing long messages. This construction uses collision-resistant hash functions as its basis. As a result, our improvements make the signature length independent of the message size. Our construction deviates from the standard hash-and-sign approach in which the hash value of the message is signed in place of the message itself. We show that in the case of twin signatures, one can exploit the properties of the hash function as an integral part of the signature scheme. This improvement can be applied to both the SRSA based and SDH based twin signature scheme.

  11. Dynamic causal modelling revisited.

    PubMed

    Friston, K J; Preller, Katrin H; Mathys, Chris; Cagnan, Hayriye; Heinzle, Jakob; Razi, Adeel; Zeidman, Peter

    2017-02-17

    This paper revisits the dynamic causal modelling of fMRI timeseries by replacing the usual (Taylor) approximation to neuronal dynamics with a neural mass model of the canonical microcircuit. This provides a generative or dynamic causal model of laminar specific responses that can generate haemodynamic and electrophysiological measurements. In principle, this allows the fusion of haemodynamic and (event related or induced) electrophysiological responses. Furthermore, it enables Bayesian model comparison of competing hypotheses about physiologically plausible synaptic effects; for example, does attentional modulation act on superficial or deep pyramidal cells - or both? In this technical note, we describe the resulting dynamic causal model and provide an illustrative application to the attention to visual motion dataset used in previous papers. Our focus here is on how to answer long-standing questions in fMRI; for example, do haemodynamic responses reflect extrinsic (afferent) input from distant cortical regions, or do they reflect intrinsic (recurrent) neuronal activity? To what extent do inhibitory interneurons contribute to neurovascular coupling? What is the relationship between haemodynamic responses and the frequency of induced neuronal activity? This paper does not pretend to answer these questions; rather it shows how they can be addressed using neural mass models of fMRI timeseries.

  12. Synthesis of silica coated zinc oxide–poly(ethylene-co-acrylic acid) matrix and its UV shielding evaluation

    SciTech Connect

    Ramasamy, Mohankandhasamy; Kim, Yu Jun; Gao, Haiyan; Yi, Dong Kee; An, Jeong Ho

    2014-03-01

    Graphical abstract: - Highlights: • Well layer thickness controlled silica shell was made on ZnO nanoparticles. • PEAA, an interfacial agent is used to make nanocomposite–polymer matrix by twin-screw extruder. • Si-ZnO/PEAA matrix is highly stable and UV protective as compared to ZnO/PEAA matrix. • Nanoparticle embedded polymer matrix is suggested to make UV shielding fabrics with Nylon4. - Abstract: Silica coated zinc oxide nanoparticles (Si-ZnO NPs) (7 nm thick) were synthesized successfully and melt blended with poly(ethylene-co-acrylic acid) (PEAA resin) to improving ultraviolet (UV) shielding of zinc oxide nanoparticles (ZnO NPs). The photostability of both the ZnO NPs and Si-ZnO NPs were analyzed by the difference in photoluminescence (PL) and by methylene blue (MB) degradation. Photo-degradation studies confirmed that Si-ZnO NPs are highly photostable compared to ZnO NPs. The melt blended matrices were characterized by field emission scanning electron microscopy interfaced with energy dispersive X-ray spectroscopy (FE-SEM-EDX). The UV shielding property was analyzed from the transmittance spectra of UV–visible (UV–vis) spectroscopy. The results confirmed fine dispersion of thick Si-ZnO NPs in the entire resin matrix. Moreover, the Si-ZnO/PEAA showed about 97% UV shielding properties than the ZnO/PEAA.

  13. A drug-in-adhesive matrix based on thermoplastic elastomer: evaluation of percutaneous absorption, adhesion, and skin irritation.

    PubMed

    Wang, ChengXiao; Liu, Ran; Tang, XiuZhen; Han, Wei

    2012-12-01

    A novel drug-in-adhesive matrix was designed and prepared. A thermoplastic elastomer, styrene-isoprene-styrene (SIS) block copolymer, in combination with tackifying resin and plasticizer, was employed to compose the matrix. Capsaicin was selected as the model drug. The drug percutaneous absorption, adhesion properties, and skin irritation were investigated. The results suggested that the diffusion through SIS matrix was the rate-limiting step of capsaicin percutaneous absorption. [SI] content in SIS and SIS proportions put important effects on drug penetration and adhesion properties. The chemical enhancers had strong interactions with the matrix and gave small effect on enhancement of drug skin permeation. The in vivo absorption of samples showed low drug plasma peaks and a steady and constant plasma level for a long period. These results suggested that the possible side effects of drug were attenuated, and the pharmacological effects were enhanced with an extended therapeutic period after application of SIS matrix. The significant differences in pharmacokinetic parameters produced by different formulations demonstrated the influences of SIS copolymer on drug penetrability. Furthermore, the result of skin toxicity test showed that no skin irritation occurred in guinea pig skin after transdermal administration of formulations.

  14. Application of matrix singular value properties for evaluating gain and phase margins of multiloop systems. [stability margins for wing flutter suppression and drone lateral attitude control

    NASA Technical Reports Server (NTRS)

    Mukhopadhyay, V.; Newsom, J. R.

    1982-01-01

    A stability margin evaluation method in terms of simultaneous gain and phase changes in all loops of a multiloop system is presented. A universal gain-phase margin evaluation diagram is constructed by generalizing an existing method using matrix singular value properties. Using this diagram and computing the minimum singular value of the system return difference matrix over the operating frequency range, regions of guaranteed stability margins can be obtained. Singular values are computed for a wing flutter suppression and a drone lateral attitude control problem. The numerical results indicate that this method predicts quite conservative stability margins. In the second example if the eigenvalue magnitude is used instead of the singular value, as a measure of nearness to singularity, more realistic stability margins are obtained. However, this relaxed measure generally cannot guarantee global stability.

  15. Evaluation of matrix-assisted laser desorption ionization-time-of-flight mass spectrometry to differentiate between Candida albicans and Candida dubliniensis.

    PubMed

    Roberts, Amity L; Alelew, Aqilah; Iwen, Peter C

    2016-05-01

    Matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF-MS) analysis in conjunction with the direct formic acid (FA) sample processing method was evaluated for the ability to differentiate the closely related species of Candida albicans and Candida dubliniensis. The results showed that MALDI-TOF-MS, using the direct FA method, was reliable to differentiate between these species.

  16. Benjamin Franklin and Mesmerism, revisited.

    PubMed

    McConkey, Kevin M; Perry, Campbell

    2002-10-01

    The authors revisit and update their previous historiographical note (McConkey & Perry, 1985) on Benjamin Franklin's involvement with and investigation of animal magnetism or mesmerism. They incorporate more recent literature and offer additional comment about Franklin's role in and views about mesmerism. Franklin had a higher degree of personal involvement with and a more detailed opinion of mesmerism than has been previously appreciated.

  17. Cultural Warping of Childbirth, Revisited

    PubMed Central

    Budin, Wendy C.

    2007-01-01

    In this column, the editor of The Journal of Perinatal Education revisits Doris Haire's classic 1972 article, “The Cultural Warping of Childbirth,” and describes the birth culture of today. The editor also describes the contents of this issue, which offer a broad range of resources, research, and inspiration for childbirth educators in their efforts to promote normal birth.

  18. The "Mushroom Cloud" Demonstration Revisited

    ERIC Educational Resources Information Center

    Panzarasa, Guido; Sparnacci, Katia

    2013-01-01

    A revisitation of the classical "mushroom cloud" demonstration is described. Instead of aniline and benzoyl peroxide, the proposed reaction involves household chemicals such as alpha-pinene (turpentine oil) and trichloroisocyanuric acid ("Trichlor") giving an impressive demonstration of oxidation and combustion reactions that…

  19. Evaluating our understanding of the biological carbon pump using the transport matrix method and global nutrient distributions.

    NASA Astrophysics Data System (ADS)

    Bernardello, Raffaele; Martin, Adrian; Khatiwala, Samar; Kriest, Iris; Henson, Stephanie; Dunne, John; Totterdell, Ian; Allen, Icarus; Yool, Andrew

    2015-04-01

    Global net primary production by marine phytoplankton plays a key role in the Earth system, fuelling the marine ecosystem and supporting resources such as fisheries. A fraction of the resulting organic material sinks out of the euphotic zone as 'export production', sequestering large amounts of carbon at depth, away from the atmosphere. Model studies have demonstrated that atmospheric pCO2 concentrations can be very sensitive to small changes in the depth at which this organic material is remineralised into CO2 and nutrients. The accuracy of parameterisations for remineralisation has often been assessed by direct comparison of simulated and sparse observed fluxes of sinking material. The consequences of remineralisation, i.e. the global distribution of inorganic nutrients, provide a much stronger test of our knowledge concerning the impact of remineralisation on ocean nutrient cycles because they are much more densely sampled. In this study, we investigate how alternative paradigms for the Biological Carbon Pump (BCP) have distinctive signatures in the consequent global distribution of nutrients. We compare several combinations of parameterisations for export production and remineralisation within two different representations of ocean circulation using the Transport Matrix Method (Khatiwala, 2007). Export production is represented using an NPZD-DOP model (Kriest et al., 2010) and three remote sensing-derived estimates while remineralisation is represented by either constant or spatially variable values of the Martin's curve exponent (Martin et al., 1987). In order to evaluate the ability of each export-remineralisation combination to correctly represent the BCP, we introduce a set of diagnostics to allow the intercomparison between in-situ data and simulations. These diagnostics are based on both nutrient fields and water masses and are designed to minimize the influence of biases originating from the representation of ocean circulation on the model

  20. Evaluating Simulations of Primary Anthropogenic and Biomass Burning Organic Aerosols using Aerosol Mass Spectrometer Data and Positive Matrix Factorization Analysis

    NASA Astrophysics Data System (ADS)

    Fast, J.; Aiken, A.; Alexander, L.; Canagaratna, M.; Decarlo, P.; Herndon, S.; Jimenez, J.; Kleinman, L.; Ochoa, C.; Onasch, T.; Song, C.; Wiedinmyer, C.; Yu, X.; Zaveri, R.

    2008-12-01

    Most model predictions of organic matter are currently underestimated because the processes contributing to secondary organic aerosol (SOA) formation and transformation are not well understood. Since research associated with developing a better framework to improve the representation of specific gas-to-particle partitioning processes controlling SOA based on new measurements and theoretical relationships is on- going, this study seeks to determine whether 3-D models can adequately predict concentrations of primary organic aerosols (POA). If one assumes POA is non-volatile, then errors in POA predictions will results from uncertainties in the emission inventories and errors in transport and mixing processes. The WRF-chem model is used to predict POA in the vicinity of Mexico City during the 2006 MILAGRO field campaign. Particulate matter emission rates were obtained from urban and regional Mexican emission inventories and from biomass burning estimates derived from MODIS "hotspot" and vegetation databases. Organic aerosol predictions are evaluated using data from Aerodyne Aerosol Mass Spectrometer (AMS) instruments deployed at four ground sites and on two research aircraft and from Sunset Laboratory OCEC instruments deployed at two ground sites. Positive Matrix Factorization (PMF) has recently been applied to derive components of organic aerosols including: hydrocarbon-like organic aerosol (HOA), oxidized organic aerosol (OOA), and biomass burning organic aerosols (BBOA). The temporal variation of HOA is often similar to primary emissions of other species in urban areas. PMF analysis is currently available for three of the ground sites and for some of the aircraft flights. We found that the predicted POA was consistently lower than the measured organic matter at the ground sites, which is consistent with the expectation that SOA should be a large fraction of the total organic aerosol mass. A much better agreement was found when predicted POA was compared with HOA

  1. Evaluation of cultured human dermal- and dermo-epidermal substitutes focusing on extracellular matrix components: Comparison of protein and RNA analysis.

    PubMed

    Oostendorp, Corien; Meyer, Sarah; Sobrio, Monia; van Arendonk, Joyce; Reichmann, Ernst; Daamen, Willeke F; van Kuppevelt, Toin H

    2017-05-01

    Treatment of full-thickness skin defects with split-thickness skin grafts is generally associated with contraction and scar formation and cellular skin substitutes have been developed to improve skin regeneration. The evaluation of cultured skin substitutes is generally based on qualitative parameters focusing on histology. In this study we focused on quantitative evaluation to provide a template for comparison of human bio-engineered skin substitutes between clinical and/or research centers, and to supplement histological data. We focused on extracellular matrix proteins since these components play an important role in skin regeneration. As a model we analyzed the human dermal substitute denovoDerm and the dermo-epidermal skin substitute denovoSkin. The quantification of the extracellular matrix proteins type III collagen and laminin 5 in tissue homogenates using western blotting analysis and ELISA was not successful. The same was true for assaying lysyl oxidase, an enzyme involved in crosslinking of matrix molecules. As an alternative, gene expression levels were measured using qPCR. Various RNA isolation procedures were probed. The gene expression profile for specific dermal and epidermal genes could be measured reliably and reproducibly. Differences caused by changes in the cell culture conditions could easily be detected. The number of cells in the skin substitutes was measured using the PicoGreen dsDNA assay, which was found highly quantitative and reproducible. The (dis) advantages of assays used for quantitative evaluation of skin substitutes are discussed.

  2. A Novel Image Analysis Approach for Evaluation of Mixing Uniformity in Drug-Filled Silicone Rubber Matrix.

    PubMed

    Karami, Samaneh; Imani, Mohammad; Farahmandghavi, Farhid

    2013-10-25

    Nowadays, there is a lot of interest in developing long-acting drug delivery devices for human or veterinary applications including monolithic systems. Drug content uniformity of a monolithic device is highly dependent on the uniform distribution of drug particles within the polymeric matrix both in dispersion and distribution levels. Here, a range of formulations were prepared which consisted of progesterone (1%w/w) and estradiol benzoate (0.1%w/w) dispersed in a silicone rubber matrix. Blend uniformity of the compounds was analyzed by image analysis of SEM micrographs obtained from the cross-sections of the devices by a new image processing approach. Efficiency of mixing was investigated at the dispersion level by plotting the relative frequency of drug particles versus "projected area diameter" of their aggregates. Based on the particle size distribution results, a significant improvement was observed in the dispersion pattern of drug particles by adding silicone oil (9%w/w). Distribution pattern of the particles was investigated by transforming the micrographs into algebraic matrices. An "ideal matrix" was developed by assumption of uniform localization of the drug particles. Real matrices obtained for all of the formulations were compared with this ideal matrix as a reference. Closer similarity between the two matrices was observed for silicone oil-containing (9%w/w) samples showing the best dispersive and distributive mixing quality.

  3. Evaluation of the matrix exponential for use in ground-water-flow and solute-transport simulations; theoretical framework

    USGS Publications Warehouse

    Umari, A.M.; Gorelick, S.M.

    1986-01-01

    It is possible to obtain analytic solutions to the groundwater flow and solute transport equations if space variables are discretized but time is left continuous. From these solutions, hydraulic head and concentration fields for any future time can be obtained without ' marching ' through intermediate time steps. This analytical approach involves matrix exponentiation and is referred to as the Matrix Exponential Time Advancement (META) method. Two algorithms are presented for the META method, one for symmetric and the other for non-symmetric exponent matrices. A numerical accuracy indicator, referred to as the matrix condition number, was defined and used to determine the maximum number of significant figures that may be lost in the META method computations. The relative computational and storage requirements of the META method with respect to the time marching method increase with the number of nodes in the discretized problem. The potential greater accuracy of the META method and the associated greater reliability through use of the matrix condition number have to be weighed against this increased relative computational and storage requirements of this approach as the number of nodes becomes large. For a particular number of nodes, the META method may be computationally more efficient than the time-marching method, depending on the size of time steps used in the latter. A numerical example illustrates application of the META method to a sample ground-water-flow problem. (Author 's abstract)

  4. Nutational Damping Revisited

    NASA Astrophysics Data System (ADS)

    Burns, J. A.; Sharma, I.

    2000-10-01

    Motivated by the recent detection of complex rotational states for several asteroids and comets, as well as by the ongoing and planned spacecraft missions to such bodies, which should allow their rotational states to be accurately determined, we revisit the problem of the nutational damping of small solar system bodies. The nutational damping of asteroids has been approximately analyzed by Prendergast (1958), Burns and Safronov (1973), and Efroimsky and Lazarian (2000). Many other similar dynamical studies concern planetary wobble decay (e.g., Peale 1973; Yoder and Ward 1979), interstellar dust grain alignment (e.g., Purcell 1979; Lazarian and Efroimsky 1999) and damping of Earth's Chandler wobble (Lambeck 1980). Recall that rotational energy loss for an isolated body aligns the body's angular momentum vector with its axis of maximum inertia. Assuming anelastic dissipation, simple dimensional analysis determines a functional form of the damping timescale, on which all the above authors agree. However, the numerical coefficients of published results are claimed to differ by orders of magnitude. Differences have been ascribed to absent physics, to solutions that fail to satisfy boundary conditions perfectly, and to unphysical choices for the Q parameter. The true reasons for the discrepancy are unclear since, despite contrary claims, the full 3D problem (nutational damping of an anelastic ellipsoid) is analytically intractable so far. To move the debate forward, we compare the solution of a related 2D problem to the expressions found previously, and we present results from a finite element model. On this basis, we feel that previous rates for the decay of asteroidal tumbling (Harris 1994), derived from Burns and Safronov (1973), are likely to be accurate, at least to a factor of a few. Funded by NASA.

  5. Recovery evaluation of organophosphorus pesticides from bee pollen by matrix solid-phase dispersion extraction using sorbents based on silica and titania

    NASA Astrophysics Data System (ADS)

    Torres-Perea, C.; Muñoz-Rodríguez, D.; Medina-Peralta, S.; Carrera-Figueiras, C.; Moguel-Ordóñez, Y. B.

    2013-06-01

    This work focused on the evaluation of the recovery of organophosphorus pesticides from bee pollen after matrix solid phase-dispersion extraction (MSPD). Materials based on silica, titania and titania modified with polivylnylimidazole or polyestirene were used as adsorbents for the extraction of pesticides. Small amounts of fortified pollen (0.1 g, at 1 micro-g/g of pesticides), adsorbent (0.4 g) and solvent elution (1 mL de acetonitrile - ACN) were used in the extractions. For recovery evaluation, pollen extracts were analyzed by gas chromatography coupled with mass spectrometry.

  6. Formulation and evaluation of ileo-colonic targeted matrix-mini-tablets of Naproxen for chronotherapeutic treatment of rheumatoid arthritis.

    PubMed

    Hadi, Mohd Abdul; Raghavendra Rao, N G; Srinivasa Rao, A

    2016-01-01

    In this present research work, the aim was to develop ileo-colonic targeted matrix-mini-tablets-filled capsule system of Naproxen for chronotherapeutic treatment of Rheumatoid Arthritis. So Matrix-mini-tablets of Naproxen were prepared using microsomal enzyme dependent and pH-sensitive polymers by direct compression method which were further filled into an empty HPMC capsule. The compatibility was assessed using FT-IR and DSC studies for pure drug, polymers and their physical mixtures. The prepared batches were subjected to physicochemical studies, drug content estimation, in-vitro drug release and stability studies. When FTIR and DSC studies were performed, it was found that there was no interaction between Naproxen and polymers used. The physicochemical properties of all the prepared matrix-mini-tablets batches were found to be in limits. The drug content percentage in the optimized formulation F18 was found to be 99.24 ± 0.10%. Our optimized matrix-mini-tablets-filled-capsule formulation F18 releases Naproxen after a lag time of 2.45 ± 0.97 h and 27.30 ± 0.86%, 92.59 ± 0.47%, 99.38 ± 0.69% at the end of 5, 8, 12 h respectively. This formulation was also found to be stable as per the guidelines of International Conference on Harmonisation of Technical Requirements of Pharmaceuticals for Human Use. Thus, a novel ileo-colonic targeted delivery system of Naproxen was successfully developed by filling matrix-mini-tablets into an empty HPMC capsule shell for targeting early morning peak symptoms of rheumatoid arthritis.

  7. Revisiting instanton corrections to the Konishi multiplet

    NASA Astrophysics Data System (ADS)

    Alday, Luis F.; Korchemsky, Gregory P.

    2016-12-01

    We revisit the calculation of instanton effects in correlation functions in N=4 SYM involving the Konishi operator and operators of twist two. Previous studies revealed that the scaling dimensions and the OPE coefficients of these operators do not receive instanton corrections in the semiclassical approximation. We go beyond this approximation and demonstrate that, while operators belonging to the same N=4 supermultiplet ought to have the same conformal data, the evaluation of quantum instanton corrections for one operator can be mapped into a semiclassical computation for another operator in the same supermultiplet. This observation allows us to compute explicitly the leading instanton correction to the scaling dimension of operators in the Konishi supermultiplet as well as to their structure constants in the OPE of two half-BPS scalar operators. We then use these results, together with crossing symmetry, to determine instanton corrections to scaling dimensions of twist-four operators with large spin.

  8. Laboratory Experiments to Evaluate Matrix Diffusion of Dissolved Organic Carbon Carbon-14 in Southern Nevada Fractured-rock Aquifers

    SciTech Connect

    Hershey, Ronald L.; Fereday, Wyatt

    2016-05-01

    Dissolved inorganic carbon (DIC) carbon-14 (14C) is used to estimate groundwater ages by comparing the DIC 14C content in groundwater in the recharge area to the DIC 14C content in the downgradient sampling point. However, because of chemical reactions and physical processes between groundwater and aquifer rocks, the amount of DIC 14C in groundwater can change and result in 14C loss that is not because of radioactive decay. This loss of DIC 14C results in groundwater ages that are older than the actual groundwater ages. Alternatively, dissolved organic carbon (DOC) 14C in groundwater does not react chemically with aquifer rocks, so DOC 14C ages are generally younger than DIC 14C ages. In addition to chemical reactions, 14C ages may also be altered by the physical process of matrix diffusion. The net effect of a continuous loss of 14C to the aquifer matrix by matrix diffusion and then radioactive decay is that groundwater appears to be older than it actually is. Laboratory experiments were conducted to measure matrix diffusion coefficients for DOC 14C in volcanic and carbonate aquifer rocks from southern Nevada. Experiments were conducted using bromide (Br-) as a conservative tracer and 14C-labeled trimesic acid (TMA) as a surrogate for groundwater DOC. Outcrop samples from six volcanic aquifers and five carbonate aquifers in southern Nevada were used. The average DOC 14C matrix diffusion coefficient for volcanic rocks was 2.9 x 10-7 cm2/s, whereas the average for carbonate rocks was approximately the same at 1.7 x 10-7 cm2/s. The average Br- matrix diffusion coefficient for volcanic rocks was 10.4 x 10-7 cm2/s, whereas the average for carbonate rocks was less at 6.5 x 10-7 cm2/s. Carbonate rocks exhibited greater variability in

  9. A matrix effect and accuracy evaluation for the determination of elements in milk powder LIBS and laser ablation/ICP-OES spectrometry.

    PubMed

    Gilon, N; El-Haddad, J; Stankova, A; Lei, W; Ma, Q; Motto-Ros, V; Yu, J

    2011-11-01

    Laser ablation coupled to inductively coupled plasma optical emission spectrometry (LA-ICP-OES) and laser-induced breakdown spectroscopy (LIBS) were investigated for the determination of Ca, Mg, Zn and Na in milk samples. The accuracy of both methods was evaluated by comparison of the concentration found using LA-ICP-OES and LIBS with classical wet digestion associated with ICP-OES determination. The results were not fully acceptable, with biases from less than 1% to more than 60%. Matrix effects were also investigated. The sample matrix can influence the temperature, electron number density (n (e)) and other excitation characteristics in the ICP. These ICP characteristics were studied and evaluated during ablation of eight milk samples. Differences in n (e) (from 8.9 to 13.8 × 10(14) cm(-3)) and rotational temperature (ranging from 3,400 to 4,400 K) occurred with no correlation with trueness. LIBS results obtained after classical external calibration procedure gave degraded accuracy, indicating a strong matrix effect. The LIBS measurements clearly showed that the major problem in LA-ICP was related to the ablation process and that LIBS spectroscopy is an excellent diagnostic tool for LA-ICP techniques.

  10. Optimization and critical evaluation of decellularization strategies to develop renal extracellular matrix scaffolds as biological templates for organ engineering and transplantation

    PubMed Central

    Caralt, Mireia; Uzarski, Joseph S.; Iacob, Stanca; Obergfell, Kyle P.; Berg, Natasha; Bijonowski, Brent M.; Kiefer, Kathryn M.; Ward, Heather H.; Wandinger-Ness, Angela; Miller, William M.; Zhang, Zheng J.; Abecassis, Michael M.; Wertheim, Jason A.

    2014-01-01

    The ability to generate patient-specific cells through induced pluripotent stem cell (iPSC) technology has encouraged development of three-dimensional extracellular matrix (ECM) scaffolds as bioactive substrates for cell differentiation with the long-range goal of bioengineering organs for transplantation. Perfusion decellularization uses the vasculature to remove resident cells, leaving an intact ECM template wherein new cells grow; however, a rigorous evaluative framework assessing ECM structural and biochemical quality is lacking. To address this, we developed histologic scoring systems to quantify fundamental characteristics of decellularized rodent kidneys: ECM structure (tubules, vessels, glomeruli) and cell removal. We also assessed growth factor retention—indicating matrix biofunctionality. These scoring systems evaluated three strategies developed to decellularize kidneys (1% Triton X-100, 1% Triton X-100/0.1% sodium dodecyl sulfate (SDS), and 0.02% Trypsin-0.05% EGTA/1% Triton X-100). Triton and Triton/SDS preserved renal microarchitecture and retained matrix-bound bFGF and VEGF. Trypsin caused structural deterioration and growth factor loss. Triton/SDS-decellularized scaffolds maintained three hours of leak-free blood flow in a rodent transplantation model and supported repopulation with human iPSC-derived endothelial cells and tubular epithelial cells ex vivo. Taken together, we identify an optimal Triton/SDS-based decellularization strategy that produces a biomatrix that may ultimately serve as a rodent model for kidney bioengineering. PMID:25403742

  11. Optimization and critical evaluation of decellularization strategies to develop renal extracellular matrix scaffolds as biological templates for organ engineering and transplantation.

    PubMed

    Caralt, M; Uzarski, J S; Iacob, S; Obergfell, K P; Berg, N; Bijonowski, B M; Kiefer, K M; Ward, H H; Wandinger-Ness, A; Miller, W M; Zhang, Z J; Abecassis, M M; Wertheim, J A

    2015-01-01

    The ability to generate patient-specific cells through induced pluripotent stem cell (iPSC) technology has encouraged development of three-dimensional extracellular matrix (ECM) scaffolds as bioactive substrates for cell differentiation with the long-range goal of bioengineering organs for transplantation. Perfusion decellularization uses the vasculature to remove resident cells, leaving an intact ECM template wherein new cells grow; however, a rigorous evaluative framework assessing ECM structural and biochemical quality is lacking. To address this, we developed histologic scoring systems to quantify fundamental characteristics of decellularized rodent kidneys: ECM structure (tubules, vessels, glomeruli) and cell removal. We also assessed growth factor retention--indicating matrix biofunctionality. These scoring systems evaluated three strategies developed to decellularize kidneys (1% Triton X-100, 1% Triton X-100/0.1% sodium dodecyl sulfate (SDS) and 0.02% Trypsin-0.05% EGTA/1% Triton X-100). Triton and Triton/SDS preserved renal microarchitecture and retained matrix-bound basic fibroblast growth factor and vascular endothelial growth factor. Trypsin caused structural deterioration and growth factor loss. Triton/SDS-decellularized scaffolds maintained 3 h of leak-free blood flow in a rodent transplantation model and supported repopulation with human iPSC-derived endothelial cells and tubular epithelial cells ex vivo. Taken together, we identify an optimal Triton/SDS-based decellularization strategy that produces a biomatrix that may ultimately serve as a rodent model for kidney bioengineering.

  12. Forest Loss and the Biodiversity Threshold: An Evaluation Considering Species Habitat Requirements and the Use of Matrix Habitats

    PubMed Central

    Estavillo, Candelaria; Pardini, Renata; da Rocha, Pedro Luís Bernardo

    2013-01-01

    Habitat loss is the main driver of the current biodiversity crisis, a landscape-scale process that affects the survival of spatially-structured populations. Although it is well-established that species responses to habitat loss can be abrupt, the existence of a biodiversity threshold is still the cause of much controversy in the literature and would require that most species respond similarly to the loss of native vegetation. Here we test the existence of a biodiversity threshold, i.e. an abrupt decline in species richness, with habitat loss. We draw on a spatially-replicated dataset on Atlantic forest small mammals, consisting of 16 sampling sites divided between forests and matrix habitats in each of five 3600-ha landscapes (varying from 5% to 45% forest cover), and on an a priori classification of species into habitat requirement categories (forest specialists, habitat generalists and open-area specialists). Forest specialists declined abruptly below 30% of forest cover, and spillover to the matrix occurred only in more forested landscapes. Generalists responded positively to landscape heterogeneity, peaking at intermediary levels of forest cover. Open area specialists dominated the matrix and did not spillover to forests. As a result of these distinct responses, we observed a biodiversity threshold for the small mammal community below 30% forest cover, and a peak in species richness just above this threshold. Our results highlight that cross habitat spillover may be asymmetrical and contingent on landscape context, occurring mainly from forests to the matrix and only in more forested landscapes. Moreover, they indicate the potential for biodiversity thresholds in human-modified landscapes, and the importance of landscape heterogeneity to biodiversity. Since forest loss affected not only the conservation value of forest patches, but also the potential for biodiversity-mediated services in anthropogenic habitats, our work indicates the importance of proactive

  13. Nondestructive evaluation of damage in SiC/Al metal matrix composite using x ray tomographic microscopy

    SciTech Connect

    Breunig, T.M.

    1992-01-01

    A fundamental understanding of damage evolution will be required before metal matrix composites (MMC) can be utilized safely for structural applications. Although macroscopic mechanical response to cyclic loading has been monitored in many mechanical and thermal test programs, little is known about the nucleation and growth of damage in MMC's. The goal of the present work is to improve the understanding of damage accumulation in SiC/Al using a new microscopic non-destructive volume-imaging technique, X-ray Tomographic Microscopy (XTM), which has resolution comparable to optical microscopy. Correlation of damage initiation and accumulation mechanisms and the macroscopic mechanical response of samples are discussed for continuous fiber SiC/Al MMC's. A series of mechanical tests were performed on a continuous, aligned fiber SiC/Al MMC, and the ensuing three-dimensional damage state was nondestructively characterized using XTM to map the x-ray absorptivity within the sample. The types of damage detected include: fiber fracture (SiC sheath, and C core), fiber-matrix interface microcracking, intra-ply matrix voids, and cracks. Quantitative three-dimensional measurements of damage are reported in as-fabricated, monotonically loaded and mechanically fatigue loaded SiC/Al. The XTM results indicate that increases in observed macroscopic structural stiffness during monotonic loading and the first few fatigue cycles of an MMC coupon correspond to elimination of processing-related matrix porosity and to displacement of the fibers from a somewhat irregular arrangement into a more nearly hexagonal array. The XTM of monotonically loaded samples also show that the carbon cores begin to fracture at or below 828 MPa, that is, at loads far less than those for fracture of the entire fiber. The fracture of the SiC sheath appears to be significantly affected by the fracture of the C cores.

  14. Forest loss and the biodiversity threshold: an evaluation considering species habitat requirements and the use of matrix habitats.

    PubMed

    Estavillo, Candelaria; Pardini, Renata; da Rocha, Pedro Luís Bernardo

    2013-01-01

    Habitat loss is the main driver of the current biodiversity crisis, a landscape-scale process that affects the survival of spatially-structured populations. Although it is well-established that species responses to habitat loss can be abrupt, the existence of a biodiversity threshold is still the cause of much controversy in the literature and would require that most species respond similarly to the loss of native vegetation. Here we test the existence of a biodiversity threshold, i.e. an abrupt decline in species richness, with habitat loss. We draw on a spatially-replicated dataset on Atlantic forest small mammals, consisting of 16 sampling sites divided between forests and matrix habitats in each of five 3600-ha landscapes (varying from 5% to 45% forest cover), and on an a priori classification of species into habitat requirement categories (forest specialists, habitat generalists and open-area specialists). Forest specialists declined abruptly below 30% of forest cover, and spillover to the matrix occurred only in more forested landscapes. Generalists responded positively to landscape heterogeneity, peaking at intermediary levels of forest cover. Open area specialists dominated the matrix and did not spillover to forests. As a result of these distinct responses, we observed a biodiversity threshold for the small mammal community below 30% forest cover, and a peak in species richness just above this threshold. Our results highlight that cross habitat spillover may be asymmetrical and contingent on landscape context, occurring mainly from forests to the matrix and only in more forested landscapes. Moreover, they indicate the potential for biodiversity thresholds in human-modified landscapes, and the importance of landscape heterogeneity to biodiversity. Since forest loss affected not only the conservation value of forest patches, but also the potential for biodiversity-mediated services in anthropogenic habitats, our work indicates the importance of proactive

  15. Fiber-matrix integrity, micromorphology and flexural strength of glass fiber posts: Evaluation of the impact of rotary instruments.

    PubMed

    Pereira, Gabriel Kalil Rocha; Lançanova, Mateus; Wandscher, Vinicius Felipe; Kaizer, Osvaldo Bazzan; Limberger, Inácio; Özcan, Mutlu; Valandro, Luiz Felipe

    2015-08-01

    Several rotary instruments have been daily employed on clinic to promote cut aiming to adjust the length of fiber posts to the radicular conduct, but there is no information on the literature about the effects of the different rotary instruments and its impact on the micromorphology of surface and mechanical properties of the glass fiber post. This study aimed the impact of rotary instruments upon fiber-matrix integrity, micromorphology and flexural-strength of glass-fiber posts (GFP). GFP (N=110) were divided into 5 groups: Ctrl: as-received posts, DBc: coarse diamond-bur, DBff: extra-fine diamond-bur, CB: carbide-bur, DD: diamond-disc. Cutting procedures were performed under abundant irrigation. Posts exposed to rotary instruments were then subjected to 2-point inclined loading test (compression 45°) (n=10/group) and 3-point flexural-strength test (n=10/group). Fiber-matrix integrity and micromorphology at the cut surface were analyzed using a SEM (n=2/group). Cutting procedures did not significantly affect the 2-point (51.7±4.3-56.7±5.1 MPa) (p=0.0233) and 3-point flexural-strength (671.5±35.3-709.1±33.1 MPa) (p=0.0968) of the posts (One-way ANOVA and Tukey׳s test). Fiber detachment was observed only at the end point of the cut at the margins of the post. Cut surfaces of the CB group were smoother than those of the other groups. After 3-point flexural strength test, fiber-matrix separation was evident at the tensile side of the post. Rotary instruments tested with simultaneous water-cooling did not affect the resistance of the tested fiber posts but caused disintegration of the fibers from the matrix at the end of the cut, located at the margins.

  16. Evaluation of a molecularly imprinted polymer for determination of steroids in goat milk by matrix solid phase dispersion.

    PubMed

    Gañán, Judith; Morante-Zarcero, Sonia; Gallego-Picó, Alejandrina; Garcinuño, Rosa María; Fernández-Hernando, Pilar; Sierra, Isabel

    2014-08-01

    A molecularly imprinted polymer-matrix solid-phase dispersion methodology for simultaneous determination of five steroids in goat milk samples was proposed. Factors affecting the extraction recovery such as sample/dispersant ratio and washing and elution solvents were investigated. The molecularly imprinted polymer used as dispersant in the matrix solid-phase dispersion procedure showed high affinity to steroids, and the obtained extracts were sufficiently cleaned to be directly analyzed. Analytical separation was performed by micellar electrokinetic chromatography using a capillary electrophoresis system equipped with a diode array detector. A background electrolyte composed of borate buffer (25mM, pH 9.3), sodium dodecyl sulfate (10mM) and acetonitrile (20%) was used. The developed MIP-MSPD methodology was applied for direct determination of testosterone (T), estrone (E1), 17β-estradiol (17β-E2), 17α-ethinylestradiol (EE2) and progesterone (P) in different goat milk samples. Mean recoveries obtained ranged from 81% to 110%, with relative standard deviations (RSD)≤12%. The molecularly imprinted polymer-matrix solid-phase dispersion method is fast, selective, cost-effective and environment-friendly compared with other pretreatment methods used for extraction of steroids in milk.

  17. A novel image analysis approach for evaluation of mixing uniformity in drug-filled silicone rubber matrix.

    PubMed

    Karami, Samaneh; Imani, Mohammad; Farahmandghavi, Farhid

    2014-01-02

    Nowadays, there is a lot of interest in developing long-acting drug delivery devices for human or veterinary applications including monolithic systems. Drug content uniformity of a monolithic device is highly dependent on the uniform distribution of drug particles within the polymeric matrix both in dispersion and distribution levels. Here, a range of formulations were prepared which consisted of progesterone (1%w/w) and estradiol benzoate (0.1%w/w) dispersed in a silicone rubber matrix. Blend uniformity of the compounds was analyzed by image analysis of SEM micrographs obtained from the cross-sections of the devices by a new image processing approach. Efficiency of mixing was investigated at the dispersion level by plotting the relative frequency of drug particles versus “projected area diameter” of their aggregates. Based on the particle size distribution results, a significant improvement was observed in the dispersion pattern of drug particles by adding silicone oil (9%w/w). Distribution pattern of the particles was investigated by transforming the micrographs into algebraic matrices. An “ideal matrix” was developed by assumption of uniform localization of the drug particles. Real matrices obtained for all of the formulations were compared with this ideal matrix as a reference. Closer similarity between the two matrices was observed for silicone oil-containing (9%w/w) samples showing the best dispersive and distributive mixing quality.

  18. Enceladus' tidal dissipation revisited

    NASA Astrophysics Data System (ADS)

    Tobie, Gabriel; Behounkova, Marie; Choblet, Gael; Cadek, Ondrej; Soucek, Ondrej

    2016-10-01

    A series of chemical and physical evidence indicates that the intense activity at Enceladus' South Pole is related to a subsurface salty water reservoir underneath the tectonically active ice shell. The detection of a significant libration implies that this water reservoir is global and that the average ice shell thickness is about 20-25km (Thomas et al. 2016). The interpretation of gravity and topography data further predicts large variations in ice shell thickness, resulting in a shell potentially thinner than 5 km in the South Polar Terrain (SPT) (Cadek et al. 2016). Such an ice shell structure requires a very strong heat source in the interior, with a focusing mechanism at the SPT. Thermal diffusion through the ice shell implies that at least 25-30 GW is lost into space by passive diffusion, implying a very efficient dissipation mechanism in Enceladus' interior to maintain such an ocean/ice configuration thermally stable.In order to determine in which conditions such a large dissipation power may be generated, we model the tidal response of Enceladus including variable ice shell thickness. For the rock core, we consider a wide range of rheological parameters representative of water-saturated porous rock materials. We demonstrate that the thinning toward the South Pole leads to a strong increase in heat production in the ice shell, with a optimal thickness obtained between 1.5 and 3 km, depending on the assumed ice viscosity. Our results imply that the heat production in the ice shell within the SPT may be sufficient to counterbalance the heat loss by diffusion and to power eruption activity. However, outside the SPT, a strong dissipation in the porous core is required to counterbalance the diffusive heat loss. We show that about 20 GW can be generated in the core, for an effective viscosity of 1012 Pa.s, which is comparable to the effective viscosity estimated in water-saturated glacial tills on Earth. We will discuss the implications of this revisited tidal

  19. Dynamic Topography Revisited

    NASA Astrophysics Data System (ADS)

    Moresi, Louis

    2015-04-01

    Dynamic Topography Revisited Dynamic topography is usually considered to be one of the trinity of contributing causes to the Earth's non-hydrostatic topography along with the long-term elastic strength of the lithosphere and isostatic responses to density anomalies within the lithosphere. Dynamic topography, thought of this way, is what is left over when other sources of support have been eliminated. An alternate and explicit definition of dynamic topography is that deflection of the surface which is attributable to creeping viscous flow. The problem with the first definition of dynamic topography is 1) that the lithosphere is almost certainly a visco-elastic / brittle layer with no absolute boundary between flowing and static regions, and 2) the lithosphere is, a thermal / compositional boundary layer in which some buoyancy is attributable to immutable, intrinsic density variations and some is due to thermal anomalies which are coupled to the flow. In each case, it is difficult to draw a sharp line between each contribution to the overall topography. The second definition of dynamic topography does seem cleaner / more precise but it suffers from the problem that it is not measurable in practice. On the other hand, this approach has resulted in a rich literature concerning the analysis of large scale geoid and topography and the relation to buoyancy and mechanical properties of the Earth [e.g. refs 1,2,3] In convection models with viscous, elastic, brittle rheology and compositional buoyancy, however, it is possible to examine how the surface topography (and geoid) are supported and how different ways of interpreting the "observable" fields introduce different biases. This is what we will do. References (a.k.a. homework) [1] Hager, B. H., R. W. Clayton, M. A. Richards, R. P. Comer, and A. M. Dziewonski (1985), Lower mantle heterogeneity, dynamic topography and the geoid, Nature, 313(6003), 541-545, doi:10.1038/313541a0. [2] Parsons, B., and S. Daly (1983), The

  20. First Grade Writers Revisit Their Work

    ERIC Educational Resources Information Center

    Hansen, Jane A.

    2007-01-01

    In this article, the author focuses on first grade readers and writers who revisit their work and describes what first-graders do when they revisit their writing about science and literature and review collections of their work. The first-graders discussed here are in Elaine O'Connor's classroom at Clark Elementary School in Charlottesville. In a…

  1. Asymptotic structure of electrodynamics revisited

    NASA Astrophysics Data System (ADS)

    Herdegen, Andrzej

    2017-03-01

    We point out that recently published analyses of null and timelike infinity and long-range structures in electrodynamics to large extent rediscover results present in the literature. At the same time, some of the conclusions these recent works put forward may prove controversial. In view of these facts, we find it desirable to revisit the analysis taken up more than two decades ago, starting from earlier works on null infinity by other authors.

  2. Matrix theory compactifications on twisted tori

    NASA Astrophysics Data System (ADS)

    Chatzistavrakidis, Athanasios; Jonke, Larisa

    2012-05-01

    We study compactifications of Matrix theory on twisted tori and noncommutative versions of them. As a first step, we review the construction of multidimensional twisted tori realized as nilmanifolds based on certain nilpotent Lie algebras. Subsequently, matrix compactifications on tori are revisited, and the previously known results are supplemented with a background of a noncommutative torus with nonconstant noncommutativity and an underlying nonassociative structure on its phase space. Next, we turn our attention to three- and six-dimensional twisted tori, and we describe consistent backgrounds of Matrix theory on them by stating and solving the conditions which describe the corresponding compactification. Both commutative and noncommutative solutions are found in all cases. Finally, we comment on the correspondence among the obtained solutions and flux compactifications of 11-dimensional supergravity, as well as on relations among themselves, such as Seiberg-Witten maps and T-duality.

  3. Fourth generation detour matrix-based topological indices for QSAR/QSPR - part-1: development and evaluation.

    PubMed

    Marwaha, Rakesh Kumar; Jangra, Harish; Das, Kinkar C; Bharatam, P V; Madan, A K

    2012-01-01

    In the present study, four detour matrix-based Topological Indices (TIs) termed as augmented path eccentric connectivity indices 1-4 (denoted by (AP)ξ(1)(C), (AP)ξ(2)(C), (AP)ξ(3)(C) and (AP)ξ(4)(C)) as well as their topochemical versions (denoted by (AP)ξ(1c)(C), (AP)ξ(2c)(C), (AP)ξ(3c)(C) and (AP)ξ(4c)(C)) have been conceptualised. A modified detour matrix termed as chemical detour matrix (Δ(c)) has also been proposed so as to facilitate computation of index values of topochemical versions of the said TIs. Values of the proposed TIs were computed for all the possible structures containing three, four and five vertices using an in-house computer program. The said TIs exhibited exceptionally high discriminating power and high sensitivity towards branching/relative position of substituent(s) in cyclic structures amalgamated with negligible degeneracy. Due care was taken during the development of TIs so as to ensure that reduction in index values of complex chemical structures to be within reasonable limits without compromising discriminating power. The mathematical properties of one of the proposed TIs have also been studied. With exceptionally high discriminating power, high sensitivity towards branching as well as relative position(s) of substituents in cyclic structures and negligible degeneracy, the proposed indices offer a vast potential for use in characterisation of structures, similarity/dissimilarity studies, lead identification and optimisation, combinatorial library design and quantitative structure-activity/property/toxicity/pharmacokinetic relationship studies.

  4. Formulation development and optimization of sustained release matrix tablet of Itopride HCl by response surface methodology and its evaluation of release kinetics

    PubMed Central

    Bose, Anirbandeep; Wong, Tin Wui; Singh, Navjot

    2012-01-01

    The objective of this present investigation was to develop and formulate sustained release (SR) matrix tablets of Itopride HCl, by using different polymer combinations and fillers, to optimize by Central Composite Design response surface methodology for different drug release variables and to evaluate drug release pattern of the optimized product. Sustained release matrix tablets of various combinations were prepared with cellulose-based polymers: hydroxy propyl methyl cellulose (HPMC) and polyvinyl pyrolidine (pvp) and lactose as fillers. Study of pre-compression and post-compression parameters facilitated the screening of a formulation with best characteristics that underwent here optimization study by response surface methodology (Central Composite Design). The optimized tablet was further subjected to scanning electron microscopy to reveal its release pattern. The in vitro study revealed that combining of HPMC K100M (24.65 MG) with pvp(20 mg)and use of LACTOSE as filler sustained the action more than 12 h. The developed sustained release matrix tablet of improved efficacy can perform therapeutically better than a conventional tablet. PMID:23960836

  5. Evaluation of gas chromatography/matrix isolation infrared spectrometry for the determination of semivolatile organic compounds in air-sample extracts

    SciTech Connect

    Childers, J.W.; Wilson, N.K.; Barbour, R.K.

    1992-01-01

    The capabilities of gas chromatography/matrix isolation-infrared (GC/MI-IR) spectrometry for determination of semivolatile organic compounds (SVOCs) in air sample extracts were evaluated. Systematic experiments, using xylene isomers as test compounds, were conducted to determine the repeatability of the steps involved in GC/MI-IR measurements and to identify parameters that affect the precision in quantitation. The repeatability of MI-IR net absorbance measurements for single and replicate depositions was determined. The MI-IR net absorbance was nonlinear at concentrations higher than 52.1 ng/microliters, probably due to an increase in the sample spot size relative to the IR beam focus or a decrease in the matrix-to-solute ratio to less than acceptable matrix isolation conditions. The method detection limit for xylene isomers was between 1 and 2 ng/microliters injected on-column for routine measurements. Extensive signal averaging was required to obtain spectra at concentrations less than 1 ng/microliters. The method was tested by determining target SVOCs in ambient air sample extracts. The MI-IR quantitative results were compared to those from the system's flame ionization detector(FID). The FID response exhibited a high bias when unknown compounds coeluted with target analytes. The ability of GC/MI-IR to quantify target compounds in the presence of interferents and to discriminate between coeluting isomers is demonstrated.

  6. Evaluation of Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry for Identification of KPC-Producing Klebsiella pneumoniae.

    PubMed

    Gaibani, Paolo; Galea, Anna; Fagioni, Marco; Ambretti, Simone; Sambri, Vittorio; Landini, Maria Paola

    2016-10-01

    We evaluated a real-time single-peak (11.109-Da) detection assay based on matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for the identification of Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae Our results demonstrated that the 11.109-Da peak was detected in 88.2% of the KPC producers. Analysis of blaKPC-producing K. pneumoniae showed that the gene encoding the 11.109-Da protein was commonly (97.8%) associated with the Tn4401a isoform.

  7. Evaluation of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry for Identification of KPC-Producing Klebsiella pneumoniae

    PubMed Central

    Galea, Anna; Fagioni, Marco; Ambretti, Simone; Sambri, Vittorio; Landini, Maria Paola

    2016-01-01

    We evaluated a real-time single-peak (11.109-Da) detection assay based on matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) for the identification of Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae. Our results demonstrated that the 11.109-Da peak was detected in 88.2% of the KPC producers. Analysis of blaKPC-producing K. pneumoniae showed that the gene encoding the 11.109-Da protein was commonly (97.8%) associated with the Tn4401a isoform. PMID:27413192

  8. The Symbol Grounding Problem Revisited: A Thorough Evaluation of the ANS Mapping Account and the Proposal of an Alternative Account Based on Symbol–Symbol Associations

    PubMed Central

    Reynvoet, Bert; Sasanguie, Delphine

    2016-01-01

    Recently, a lot of studies in the domain of numerical cognition have been published demonstrating a robust association between numerical symbol processing and individual differences in mathematics achievement. Because numerical symbols are so important for mathematics achievement, many researchers want to provide an answer on the ‘symbol grounding problem,’ i.e., how does a symbol acquires its numerical meaning? The most popular account, the approximate number system (ANS) mapping account, assumes that a symbol acquires its numerical meaning by being mapped on a non-verbal and ANS. Here, we critically evaluate four arguments that are supposed to support this account, i.e., (1) there is an evolutionary system for approximate number processing, (2) non-symbolic and symbolic number processing show the same behavioral effects, (3) non-symbolic and symbolic numbers activate the same brain regions which are also involved in more advanced calculation and (4) non-symbolic comparison is related to the performance on symbolic mathematics achievement tasks. Based on this evaluation, we conclude that all of these arguments and consequently also the mapping account are questionable. Next we explored less popular alternative, where small numerical symbols are initially mapped on a precise representation and then, in combination with increasing knowledge of the counting list result in an independent and exact symbolic system based on order relations between symbols. We evaluate this account by reviewing evidence on order judgment tasks following the same four arguments. Although further research is necessary, the available evidence so far suggests that this symbol–symbol association account should be considered as a worthy alternative of how symbols acquire their meaning. PMID:27790179

  9. Revisiting the matricellular concept.

    PubMed

    Murphy-Ullrich, Joanne E; Sage, E Helene

    2014-07-01

    The concept of a matricellular protein was first proposed by Paul Bornstein in the mid-1990s to account for the non-lethal phenotypes of mice with inactivated genes encoding thrombospondin-1, tenascin-C, or SPARC. It was also recognized that these extracellular matrix proteins were primarily counter or de-adhesive. This review reappraises the matricellular concept after nearly two decades of continuous investigation. The expanded matricellular family as well as the diverse and often unexpected functions, cellular location, and interacting partners/receptors of matricellular proteins are considered. Development of therapeutic strategies that target matricellular proteins are discussed in the context of pathology and regenerative medicine.

  10. Revisiting the matricellular concept

    PubMed Central

    Murphy-Ullrich, Joanne E.; Sage, E. Helene

    2015-01-01

    The concept of a matricellular protein was first proposed by Paul Bornstein in the mid-1990s to account for the non-lethal phenotypes of mice with inactivated genes encoding thrombospondin-1, tenascin-C, or SPARC. It was also recognized that these extracellular matrix proteins were primarily counter or de-adhesive. This review reappraises the matricellular concept after nearly two decades of continuous investigation. The expanded matricellular family as well as the diverse and often unexpected functions, cellular location, and interacting partners/receptors of matricellular proteins are considered. Development of therapeutic strategies that target matricellular proteins are discussed in the context of pathology and regenerative medicine. PMID:25064829

  11. UV-MALDI mass spectrometric quantitation of uracil based pesticides in fruit soft drinks along with matrix effects evaluation.

    PubMed

    Ivanova, Bojidarka; Spiteller, Michael

    2014-02-01

    This study focused on the development of the accurate and precise quantitative method for the determination of pesticides bromacil (1), terbacil (2), lenacil (3), butafenacil (4) and flupropacil (5) in fruit based soft drinks. Three different types of drinks are bought from market; huddled orange fruit drink (100%) (I), red-oranges (II) and multivitamin drink containing strawberry, orange, banana and maracuja (III). Samples were analyzed "with" and "without" pulp utilizing LC-ESI (or APCI) MS/MS, HPLC-ESI-(or APCI)-MS/MS and UV-MALDI-Orbitrap-MS methods. The effect of high complexity of the food matrix on the analysis was discussed. Study focuses on the advantages of the UV-MALDI-Orbitrap-MS method compared to the traditionally involved GC alone or hybrid methods such as GC-MS and LC-MS/MS for quantification of pesticides in water and soft drinks. The developed method included the techniques performed for validation, calibration and standardization. The target pesticides are widely used for the treatment of citrus fruits and pineapples, but for soft drink products, there are still no clear regulations on pesticide residues limits. The matrix effects in the analysis of fruit drinks required implementation of the exact standard reference material corresponds to the variety of food matrices. This paper contributed to the broad analytical implementation of the UV-MALDI-Orbitrap-MS method in the quality control and assessment programs for monitoring of pesticide contamination in fruit based sodas.

  12. Radiolytic Cryovolcanism Revisited

    NASA Astrophysics Data System (ADS)

    Cooper, J. F.; Cooper, P. D.; Sittler, E. C.; Wesenberg, R. P.

    2013-12-01

    Active geysers of water vapor and ice grains from the south pole of Enceladus are not yet definitively explained in terms of energy sources and processes. Other instances of hot (Io) and cold (Mars, Triton) volcanism beyond Earth are known if not fully understood. We revisit, in comparison to other models, the 'Old Faithful' theory of radiolytic gas-driven cryovolcanism first proposed by Cooper et al. [Plan. Sp. Sci. 2009]. In the energetic electron irradiation environment of Enceladus within Saturn's magnetosphere, a 10-percent duty cycle could be maintained for current geyser activity driven by gases from oxidation of ammonia to N2 and methane to CO2 in the thermal margins of a south polar sea. Much shorter duty cycles down to 0.01 percent would be required to account for thermal power output up to 16 GW, Steady accumulation of oxidant energy over four billion years could have powered all Enceladus emissions over the past four hundred thousand to four hundred million years. There could be separate energy sources driving mass flow and thermal emission over vastly different time scales. Since episodic tidal dissipation on 10 Myr time scales at 0.1 - 1 Gyr intervals [O'Neill and Nimmo, Nature 2010], and thus duty cycles 1 - 10 percent, could heat the polar sea to the current level, the radiolytic energy source could easily power and modulate the geyser mass flow on million-year time scales. Maximum thermal emission temperature 223 K [Abramov and Spencer, Icarus 2009] hints at thermal buffering in the basal and vent wall layers by a 1:1 H2O:H2O2 radiolytic eutectic, assuming deep ice crust saturation with H2O2 from long cumulative surface irradiation and downward ice convection. Due to density stratification the peroxide eutectic and salt water layers could separate, so that the denser peroxide layer (1.2 g/cc) descends to the polar sea while the lighter salt water (1.05 g/cc) rises along separate channels. Methane reservoirs could be found dissolved into the polar

  13. Science deserves to be judged by its contents, not by its wrapping: Revisiting Seglen's work on journal impact and research evaluation

    PubMed Central

    Rousseau, Ronald; Sivertsen, Gunnar

    2017-01-01

    The scientific foundation for the criticism on the use of the Journal Impact Factor (JIF) in evaluations of individual researchers and their publications was laid between 1989 and 1997 in a series of articles by Per O. Seglen. His basic work has since influenced initiatives such as the San Francisco Declaration on Research Assessment (DORA), the Leiden Manifesto for research metrics, and The Metric Tide review on the role of metrics in research assessment and management. Seglen studied the publications of only 16 senior biomedical scientists. We investigate whether Seglen’s main findings still hold when using the same methods for a much larger group of Norwegian biomedical scientists with more than 18,000 publications. Our results support and add new insights to Seglen’s basic work. PMID:28350849

  14. Science deserves to be judged by its contents, not by its wrapping: Revisiting Seglen's work on journal impact and research evaluation.

    PubMed

    Zhang, Lin; Rousseau, Ronald; Sivertsen, Gunnar

    2017-01-01

    The scientific foundation for the criticism on the use of the Journal Impact Factor (JIF) in evaluations of individual researchers and their publications was laid between 1989 and 1997 in a series of articles by Per O. Seglen. His basic work has since influenced initiatives such as the San Francisco Declaration on Research Assessment (DORA), the Leiden Manifesto for research metrics, and The Metric Tide review on the role of metrics in research assessment and management. Seglen studied the publications of only 16 senior biomedical scientists. We investigate whether Seglen's main findings still hold when using the same methods for a much larger group of Norwegian biomedical scientists with more than 18,000 publications. Our results support and add new insights to Seglen's basic work.

  15. The guinea-pig skin sensitization test revisited: an evaluation formula to predict possible sensitization levels for eight chemicals used in household products.

    PubMed

    Momma, J; Kitajima, S; Inoue, T

    1998-02-20

    In predicting human skin sensitization due to possible risky chemicals, it is not sufficient to evaluate solely the minimum induction dose (MID) or the standard challenge dose (SCD) in the Guinea Pig Maximization Test (GPMT). Nakamura et al. (1994) (Nakamura, A., Momma, J., Sekiguchi, H., Noda, T., Yamano, T., Kaniwa, M., Kojima, S., Tsuda, M., Kurokawa, Y., 1994. A new protocol and criteria for quantitative determination of sensitization potencies of chemicals by guinea pig maximization test. Contact Dermatitis 31, 72-85) previously measured the residual dose of chemicals in the products implicated in human allergic accidents, and stated that '... the level of chemical in the products (direct exposure-dose = DED) was similar to or higher than value of sensitization potency.' However, several of the chemicals listed in their article, show an even lower value of sensitization potency than the DED, although a potential correlation between results of the GPMT and the DED was seemed to be evident; a key question about the essential rule of those parameters therefore remains open. Using the data of Nakamura et al. (1994), we analyzed the functional rules of the three independent parameters, the MID, the SCD, and the DED on which the GPMT is based. Calculations of the degree of allergic reactions elicited in humans provided a range of discrimination constants (D) using the formula; D = DED/(MID*SCD). Possible human allergic accidents may be predicted when the dose of a candidate chemical in a chemical product (equal to DED) exceeds the value; D*(MID*SCD), following the correct evaluation of the MID as well as the SCD.

  16. Development and Psychometric Evaluation of the Hansen Research Services Matrix Adaptive Test: A Measure of Nonverbal IQ.

    PubMed

    Hansen, John A

    2016-10-13

    Assessment of individuals on the autism spectrum often includes a measure of nonverbal IQ. One such measure is the Raven's Standard Progressive Matrices (RSPM). For large research studies with participants distributed nationally it is desirable for assessments to be available online. Because time is a premium, it is ideal that the measure produces accurate scores quickly. The Hansen Research Services Matrix Adaptive Test (HRS-MAT) addresses these needs and with similar psychometric properties of the RSPM. Scores based on the HRS-MAT correlated at r = .81 with those of the RSPM. In adult-child pairs, HRS-MAT scores correlated at approximately r = .50. Details from respondents in a national sample and psychometric properties including reliability and validity are discussed.

  17. Occupational exposures and chronic obstructive pulmonary disease (COPD): comparison of a COPD-specific job exposure matrix and expert-evaluated occupational exposures

    PubMed Central

    Kurth, Laura; Doney, Brent; Weinmann, Sheila

    2017-01-01

    Objectives To compare the occupational exposure levels assigned by our National Institute for Occupational Safety and Health chronic obstructive pulmonary disease-specific job exposure matrix (NIOSH COPD JEM) and by expert evaluation of detailed occupational information for various jobs held by members of an integrated health plan in the Northwest USA. Methods We analysed data from a prior study examining COPD and occupational exposures. Jobs were assigned exposure levels using 2 methods: (1) the COPD JEM and (2) expert evaluation. Agreement (Cohen’s κ coefficients), sensitivity and specificity were calculated to compare exposure levels assigned by the 2 methods for 8 exposure categories. Results κ indicated slight to moderate agreement (0.19–0.51) between the 2 methods and was highest for organic dust and overall exposure. Sensitivity of the matrix ranged from 33.9% to 68.5% and was highest for sensitisers, diesel exhaust and overall exposure. Specificity ranged from 74.7% to 97.1% and was highest for fumes, organic dust and mineral dust. Conclusions This COPD JEM was compared with exposures assigned by experts and offers a generalisable approach to assigning occupational exposure. PMID:27777373

  18. Increasing the Degrees of Freedom in Future Group Randomized Trials: The "df*" Method Revisited

    ERIC Educational Resources Information Center

    Murray, David M.; Blitstein, Jonathan L.; Hannan, Peter J.; Shadish, William R.

    2012-01-01

    Background: This article revisits an article published in Evaluation Review in 2005 on sample size estimation and power analysis for group-randomized trials. With help from a careful reader, we learned of an important error in the spreadsheet used to perform the calculations and generate the results presented in that article. As we studied the…

  19. Evaluation of tissue-engineered bone constructs using rabbit fetal osteoblasts on acellular bovine cancellous bone matrix

    PubMed Central

    Rashmi; Pathak, Rekha; Amarpal; Aithal, H. P.; Kinjavdekar, P.; Pawde, A. M.; Tiwari, A. K.; Sangeetha, P.; Tamilmahan, P.; Manzoor, A. B.

    2017-01-01

    Aim: The aim of this study was to generate composite bone graft and investigate the rabbit fetal osteoblasts adhesion, proliferation and penetration on acellular matrices of cancellous bone. Materials and Methods: Acellular cancellous bone was prepared and developed as in the previous study with little modification. These matrices were decellularized by rapid freeze and thaw cycle. To remove the cell debris, they were then treated with hydrogen peroxide (3%) and ethanol to remove antigenic cellular and nuclear materials from the scaffold. Primary osteoblast cells were harvested from 20 to 22 days old rabbit fetal long and calvarial bone. These cells were cultured and characterized using a specific marker. The third passaged fetal osteoblast cells were then seeded on the scaffold and incubated for 14 days. The growth pattern of the cells was observed. Scanning electron microscope and hematoxylin and eosin staining were used to investigate cells proliferation. Results: The cells were found to be growing well on the surface of the scaffold and were also present in good numbers with the matrix filopodial extensions upto inside of the core of the tissue. Conclusion: Thus, a viable composite scaffold of bone could be developed which has a great potential in the field of bone tissue engineering. PMID:28344398

  20. Complexity curve and grey level co-occurrence matrix in the texture evaluation of breast tumor on ultrasound images.

    PubMed

    Alvarenga, André Victor; Pereira, Wagner C A; Infantosi, Antonio Fernando C; Azevedo, Carolina M

    2007-02-01

    This work aims at investigating texture parameters in distinguishing malign and benign breast tumors on ultrasound images. A rectangular region of interest (ROI) containing the tumor and its neighboring was defined for each image. Five parameters were extracted from the complexity curve (CC) of the ROI. Another five parameters were calculated from the grey-level co-occurrence matrix (GLCM) also for the ROI. The same was carried out for internal tumor region, hence, totaling 20 parameters. The linear discriminant analysis was applied to sets of up to five parameters and then the performances were assessed. The most relevant individual parameters were the contrast (con) (from the GLCM over the ROI) and the maximum value (mvi) from the CC just for the tumor internal region). When they were taken together, a correct classification slightly over 80% of the breast tumors was achieved. The highest performance (accuracy=84.2%, sensitivity=87.0%, and specificity=78.8%) was obtained with mvi, con, the standard deviation of the pixel pairs and the entropy, both for GLCM, and the internal region contrast also from GLCM. Parameters extracted from the internal region generally performed better and were more significant than those from the ROI. Moreover, parameters calculated only from CC or GLCM resulted in no statistically significant performance difference. These findings suggest that the texture parameters can be useful to help radiologist in distinguishing between benign or malign breast tumors on ultrasound images.

  1. Representing 3-D cloud radiation effects in two-stream schemes: 2. Matrix formulation and broadband evaluation

    NASA Astrophysics Data System (ADS)

    Hogan, Robin J.; Schäfer, Sophia A. K.; Klinger, Carolin; Chiu, J. Christine; Mayer, Bernhard

    2016-07-01

    Estimating the impact of radiation transport through cloud sides on the global energy budget is hampered by the lack of a fast radiation scheme suitable for use in global atmospheric models that can represent these effects in both the shortwave and longwave. This two-part paper describes the development of such a scheme, which we refer to as the Speedy Algorithm for Radiative Transfer through Cloud Sides (SPARTACUS). The principle of the method is to add extra terms to the two-stream equations to represent lateral transport between clear and cloudy regions, which vary in proportion to the length of cloud edge as a function of height. The present paper describes a robust and accurate method for solving the coupled system of equations in both the shortwave and longwave in terms of matrix exponentials. This solver has been coupled to a correlated-k model for gas absorption. We then confirm the accuracy of SPARTACUS by performing broadband comparisons with fully 3-D radiation calculations by the Monte Carlo model "MYSTIC" for a cumulus cloud field, examining particularly the percentage change in cloud radiative effect (CRE) when 3-D effects are introduced. In the shortwave, SPARTACUS correctly captures this change to CRE, which varies with solar zenith angle between -25% and +120%. In the longwave, SPARTACUS captures well the increase in radiative cooling of the cloud, although it is only able to correctly simulate the 30% increase in surface CRE (around 4 W m-2) if an approximate correction is made for cloud clustering.

  2. Evaluation of Influence of Various Polymers on Dissolution and Phase Behavior of Carbamazepine-Succinic Acid Cocrystal in Matrix Tablets.

    PubMed

    Ullah, Majeed; Ullah, Hanif; Murtaza, Ghulam; Mahmood, Qaisar; Hussain, Izhar

    2015-01-01

    The aim of current study was to explore the influence of three commonly used polymers, that is, cellulosics and noncellulosics, for example, Methocel K4M, Kollidon VA/64, and Soluplus, on the phase disproportionation and drug release profile of carbamazepine-succinic acid (CBZ-SUC) cocrystal at varying drug to polymer ratios (1 : 1 to 1 : 0.25) in matrix tablets. The polymorphic phase disproportionation during in-depth dissolution studies of CBZ-SUC cocrystals and its crystalline properties were scrutinized by X-ray powder diffractrometry and Raman spectroscopy. The percent drug release from HPMC formulations (CSH) showed inverse relation with the concentration of polymer; that is, drug release increased with decrease in polymer concentration. On contrary, direct relation was observed between percent drug release and polymer concentrations of Kollidon VA 64/Soluplus (CSK, CSS). At similar polymer concentration, drug release from pure carbamazepine was slightly lower with HPMC formulations than that of cocrystal; however, opposite trend in release rate was observed with Kollidon VA/64 and Soluplus. The significant increase in dissolution rate of cocrystal occurred with Kollidon VA/64 and Soluplus at higher polymer concentration. Moreover, no phase change took place in Methocel and Kollidon formulations. No tablet residue was left for Soluplus formulation so the impact of polymer on cocrystal integrity cannot be predicted.

  3. Evaluation of Kitson's therapeutic nursing function matrix in the assessment of quality of nursing care in hospital.

    PubMed

    Norman, I J; Redfern, S J; Oliver, S; Tomalin, D A

    1994-08-01

    This paper describes our test of Kitson's structured observation and scoring technique (the Therapeutic Nursing Function Matrix--TNFM) and our development of her technique (referred to as the Quality Assessment Project scheme--QAP scheme) as methods of assessing the quality of patient care in hospital wards. Both techniques were tested for inter-observer reliability and for validity against continuous observation. Kitson's technique and the QAP scheme reached acceptable levels of inter-observer agreement for identification of patients' activities, but not for scoring of those activities. Overall, the QAP scheme was found to be more reliable than the Kitson technique. Validity testing against continuous observation again revealed acceptable levels of inter-observer agreement for identification of activities, but not for scoring of those activities. For the Kitson technique there was virtually no agreement in scoring between observers. The QAP scheme achieved higher agreement but needs further work to iron out problems of detail. The conclusion reached is that the QAP scheme is a promising method for assessing the quality of nursing care in hospital wards.

  4. Evaluation of polycyclic aromatic hydrocarbons in asphalt binder using matrix solid-phase dispersion and gas chromatography.

    PubMed

    Fernandes, Paulo R N; Soares, Sandra de A; Nascimento, Ronaldo F; Soares, Jorge B; Cavalcante, Rivelino M

    2009-10-01

    A method developed for the extraction and analysis of polycyclic aromatic hydrocarbons (PAHs) in the asphalt binder using a matrix solid-phase dispersion (MSPD) and gas chromatography is presented. The MSPD method was proposed as a rapid and easy approach to determining PAHs present in the maltenic phase of asphalt binder extracted through a mechanical shaking and sonication of the material. The recovery rates ranged from 62.77-89.92% (shaking) and from 56.54-93.6% (sonication) with relative standard deviations lower than 8.8%. The study shows that the recovery rates using shaking and sonication extractions are not significantly different at the p < 0.05 level. The limits of detection and quantification ranged from 0.7-1.8 mg/kg and 2.2-5.6 mg/kg, respectively. The proposed analytical method was applied to determine PAH levels in an asphalt binder from Brazil. The main PAHs found were BbF, BaP, Per, IncdP, DahA, and BghiP, with average concentrations of 10.2-20.7 mg/kg, but the PAHs Ace and Acy were not detected. However, Nap, Fl, Phen, Ant, Flr, Pyr, Chry, BaA, and BkF were present in average concentrations amounting to less than 10 mg/kg. The results showed that the MSPD method is potentially a valuable tool for the determination of PAHs in the asphalt binder.

  5. Formulation and in vitro evaluation of theophylline matrix tablets prepared by direct compression: Effect of polymer blends.

    PubMed

    El-Bagory, Ibrahim; Barakat, Nahla; Ibrahim, Mohamed A; El-Enazi, Fouza

    2012-07-01

    The deformation mechanism of pharmaceutical powders, used in formulating directly compressed matrix tablets, affects the characteristics of the formed tablets. Three polymers of different deformation mechanisms were tested for their impact on theophylline directly compressed tablets namely Kollidon SR (KL SR, plastic deformation), Ethylcellulose (EC, elastic deformation) and Carnauba wax (CW, brittle deformation) at different compression forces. However, tablets based mainly on KL SR, the plastically deformed polymer (TN1) exhibited the highest hardness values compared to the other formulae which are based on either blends of KL SR with CW, the very brittle deformed polymer. The upper detected force for TN formulae and the lower punch force were found to dependent mainly on the powder deformation. This difference is attributed to the work done during the compression phase as well as the work lost during the decompression phase. Furthermore, the release profiles of TN from formulae TN2 and TN4 that are based on the composition (2KL SR:1EC) and (1KL SR:2EC), respectively, were consistent with different deformation mechanisms of KL SR and EC and on the physicochemical properties like the water absorptive capacity of EC. Upon increasing the weight ratio of KL SR (TN2), the release rate was greatly retarded (39.4%, 37.1%, 35.0% and 33.6% released after 8 h at 5, 10, 15 and 20 kN.

  6. Formulation and in vitro evaluation of theophylline matrix tablets prepared by direct compression: Effect of polymer blends

    PubMed Central

    El-Bagory, Ibrahim; Barakat, Nahla; Ibrahim, Mohamed A.; El-Enazi, Fouza

    2011-01-01

    The deformation mechanism of pharmaceutical powders, used in formulating directly compressed matrix tablets, affects the characteristics of the formed tablets. Three polymers of different deformation mechanisms were tested for their impact on theophylline directly compressed tablets namely Kollidon SR (KL SR, plastic deformation), Ethylcellulose (EC, elastic deformation) and Carnauba wax (CW, brittle deformation) at different compression forces. However, tablets based mainly on KL SR, the plastically deformed polymer (TN1) exhibited the highest hardness values compared to the other formulae which are based on either blends of KL SR with CW, the very brittle deformed polymer. The upper detected force for TN formulae and the lower punch force were found to dependent mainly on the powder deformation. This difference is attributed to the work done during the compression phase as well as the work lost during the decompression phase. Furthermore, the release profiles of TN from formulae TN2 and TN4 that are based on the composition (2KL SR:1EC) and (1KL SR:2EC), respectively, were consistent with different deformation mechanisms of KL SR and EC and on the physicochemical properties like the water absorptive capacity of EC. Upon increasing the weight ratio of KL SR (TN2), the release rate was greatly retarded (39.4%, 37.1%, 35.0% and 33.6% released after 8 h at 5, 10, 15 and 20 kN. PMID:24115902

  7. Optimal Topology and Experimental Evaluation of Piezoelectric Materials for Actively Shunted General Electric Polymer Matrix Fiber Composite Blades

    NASA Technical Reports Server (NTRS)

    Choi, Benjamin B.; Duffy, Kirsten; Kauffman, Jeffrey L.; Kray, Nicholas

    2012-01-01

    NASA Glenn Research Center, in collaboration with GE Aviation, has begun the development of a smart adaptive structure system with piezoelectric (PE) transducers to improve composite fan blade damping at resonances. Traditional resonant damping approaches may not be realistic for rotating frame applications such as engine blades. The limited space in which the blades reside in the engine makes it impossible to accommodate the circuit size required to implement passive resonant damping. Thus, a novel digital shunt scheme has been developed to replace the conventional electric passive shunt circuits. The digital shunt dissipates strain energy through the load resistor on a power amplifier. General Electric (GE) designed and fabricated a variety of polymer matrix fiber composite (PMFC) test specimens. Investigating the optimal topology of PE sensors and actuators for each test specimen has revealed the best PE transducer location for each target mode. Also a variety of flexible patches, which can conform to the blade surface, have been tested to identify the best performing PE patch. The active damping control achieved significant performance at target modes. This work has been highlighted by successful spin testing up to 5000 rpm of subscale GEnx composite blades in Glenn s Dynamic Spin Rig.

  8. Optimal topology and experimental evaluation of PE materials for actively shunted GE polymer matrix fiber composite blades

    NASA Astrophysics Data System (ADS)

    Choi, Benjamin B.; Duffy, Kirsten; Kauffman, Jeffrey L.; Kray, Nicholas

    2012-04-01

    NASA Glenn Research Center (GRC), in collaboration with GE Aviation, has begun the development of a smart adaptive structure system with piezoelectric transducers to improve composite fan blade damping at resonances. Traditional resonant damping approaches may not be realistic for rotating frame applications such as engine blades. The limited space in which the blades reside in the engine makes it impossible to accommodate the circuit size required to implement passive resonant damping. Thus, we have developed a novel digital shunt scheme to replace the conventional electric passive shunt circuits. The digital shunt dissipates strain energy through the load capacitor on a power amplifier. GE designed and fabricated a variety of polymer matrix fiber composite (PMFC) test specimens. We investigated the optimal topology of PE sensors and actuators for each test specimen to discover the best PE transducer location for each target mode. Also a variety of flexible patches, which can conform to the blade surface, have been tested to identify the best performing piezoelectric patch. The active damping control achieved significant performance at target modes. This work has been highlighted by successful spin testing up to 5,000 rpm of subscale GEnx composite blades in GRC's Dynamic Spin Rig.

  9. Lithium in the Pleiades Revisited

    NASA Astrophysics Data System (ADS)

    King, J. R.; Hobbs, L. M.; Schuler, S. C.; Pinsonneault, M. H.

    2003-12-01

    New Li abundances have been derived for some 15-20 Pleiades dwarfs using new high-resolution and high S/N spectroscopy from HET/HRS. Previous studies suggested that our objects, all modest (projected) rotators, evinced considerable scatter in their Li abundances. We revisit the question of this scatter and its origin. This work has been supported by NSF grants AST 00-86576 and 02-39518, a South Carolina Space Grant Scholarship award, a generous donation from the Curry Foundation of Seneca, SC, and the NOAO Public Access Program.

  10. Reticulin immunostaining revisited

    PubMed Central

    Torres, Kara Melissa T.; Kazlouskaya, Viktoryia; Parikh, Kruti; Elston, Dirk M.

    2016-01-01

    Introduction: Reticulin staining has been suggested as an inexpensive tool in the differential diagnosis of melanoma versus benign nevi. In the present study, reticulin immunostaining patterns in malignant melanomas, benign intradermal nevi, and blue nevi were observed. The concordance in evaluation of the pattern between observers was also done. Materials and Methods: A retrospective search was performed in the computer database of the Ackerman Academy of Dermatopathology for “melanoma,” “melanocytic nevus,” and “blue nevus”. Fifty-six melanomas (30 of nodular subtype and 26 of superficial spreading subtype), 54 benign compound nevi, and 27 blue nevi were selected for the study. Patterns of reticulin staining in the dermis and the basement membrane in these melanocytic lesions were evaluated and the concordance between the two groups of authors was assessed. Statistical evaluation was performed with the Statistica® 10 program, Tulsa, OK. Concordance of the pattern evaluation was evaluated using Cohen's kappa coefficient. Results: Melanomas show a variable basement membrane pattern some of which show flat, thin and smooth pattern. Benign nevi almost never showed this flat pattern at the basement membrane zone. In the dermis, melanomas showed reticulin fibers surrounding groups of melanocytic cells while nevi predominantly had reticulin fibers around individual cells. There was greater agreement in evaluating the dermal component compared to the basement membrane pattern. Conclusion: The dermal reticulin staining pattern may be of some value in the diagnosis of melanocytic lesions, but poor concordance in evaluation of the basement membrane zone pattern limits its usefulness. PMID:26955582

  11. Human acellular dermal matrix allograft: A randomized, controlled human trial for the long-term evaluation of patients with extensive burns.

    PubMed

    Li, Xueyong; Meng, Xianghai; Wang, Xiaolin; Li, Yuejun; Li, Wangzhou; Lv, Xiaoxing; Xu, Xiaoli; Lei, Zhanjun; Li, Jinqing

    2015-06-01

    The potential of acellular dermal matrix (ADM) to improve cosmetic and functional outcomes has been demonstrated; however, there have been few clinical comparative studies assessing the long-term morphological, histological and functional changes after ADM placement. This study was designed to retrospectively evaluate the long-term outcomes of the cograft acellular dermal matrix with autologous thin split-thickness skin for the coverage of wounds in extensively burned patients. Thirty burn patients treated with a composite graft of ADM with autologous split-thickness skin from January 2007 to December 2009 were enrolled in this study. Another group of thirty patients who received only an autogenous split-thickness skin implant served as the control. Our study revealed that the collagen in the dermis treated with ADM were ordered, and the proportion of collagen III/I was much higher in the control group than in the ADM group. The basement membrane was prominent and continuous. Meanwhile, the VBSS (Vancouver Burn Skin Score) was used to evaluate skin quality, which shows a significant differences between the two group (P<0.001). Then the functional level was evaluated by the BI (Barthel Index), and the ADM group was much better than the control group (P=0.005). Based on these results, we concluded that the composite graft of ADM with autologous thin split-thickness skin was suitable for repairing the defects in functional areas after a burn. This technique might facilitate wound management with acceptable esthetic outcomes, good functional recovery and less scar hyperplasia at the donor site.

  12. Evaluation of Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry for Identification of Nocardia Species▿

    PubMed Central

    Verroken, A.; Janssens, M.; Berhin, C.; Bogaerts, P.; Huang, T.-D.; Wauters, G.; Glupczynski, Y.

    2010-01-01

    The identification of Nocardia species, usually based on biochemical tests together with phenotypic in vitro susceptibility and resistance patterns, is a difficult and lengthy process owing to the slow growth and limited reactivity of these bacteria. In this study, a panel of 153 clinical and reference strains of Nocardia spp., altogether representing 19 different species, were characterized by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). As reference methods for species identification, full-length 16S rRNA gene sequencing and phenotypical biochemical and enzymatic tests were used. In a first step, a complementary homemade reference database was established by the analysis of 110 Nocardia isolates (pretreated with 30 min of boiling and extraction) in the MALDI BioTyper software according to the manufacturer's recommendations for microflex measurement (Bruker Daltonik GmbH, Leipzig, Germany), generating a dendrogram with species-specific cluster patterns. In a second step, the MALDI BioTyper database and the generated database were challenged with 43 blind-coded clinical isolates of Nocardia spp. Following addition of the homemade database in the BioTyper software, MALDI-TOF MS provided reliable identification to the species level for five species of which more than a single isolate was analyzed. Correct identification was achieved for 38 of the 43 isolates (88%), including 34 strains identified to the species level and 4 strains identified to the genus level according to the manufacturer's log score specifications. These data suggest that MALDI-TOF MS has potential for use as a rapid (<1 h) and reliable method for the identification of Nocardia species without any substantial costs for consumables. PMID:20861335

  13. Molecular sieving of hyaluronan by synovial interstitial matrix and lymphatic capillary endothelium evaluated by lymph analysis in rabbits.

    PubMed

    Sabaratnam, S; Mason, R M; Levick, J R

    2003-11-01

    Synovial fluid hyaluronan (HA) profoundly buffers fluid loss from joints. This is attributed to the osmotic pressure of HA reflected by the joint lining. The aims were to quantify HA sieving during fluid drainage from joint to lymphatics and to compare the contributions of the synovial lining and lymphatic endothelium to sieving. HA (2100 kDa) and fluorescein-dextran (FD, 20 kDa) were infused under constant pressure into the knee cavity in anaesthetised rabbits. Samples were taken of femoral lymph and, after approximately 3-h transsynovial filtration, subsynovial fluid and mixed intra-articular fluid. [HA] and [FD] were analysed by HPLC and reflection was calculated as one minus transmitted fraction. Subsynovial and lymph [HA] were 16 and 12% of intra-articular [HA], which increased to 2.6 times infusate [HA] (P < 0.001, ANOVA, n = 19). [FD] was not significantly changed in infusate, aspirate, and subsynovial fluid but fell to 62% in femoral lymph due to dilution by skin/muscle lymph. The HA reflected fraction for the cavity-to-lymph barrier, R(lymph), was 0.54 +/- 0.03 (n = 82, mean +/- SEM), compared with 0.51 +/- 0.07 for cavity-to-subsynovium (R(syn), P > 0.05, Bonferroni) and 0.07 +/- 0.18 for subynovium-to-lymph (R(endo), P < 0.0001, Bonferroni). Lymphatic capillary endothelial reflection R(endo) was not significantly different from zero (one-sample t test). It is concluded that HA is partially sieved out of fluid leaving the joint cavity, and the sieve is the synovial lining interstitial matrix, not lymphatic capillary endothelium.

  14. Evaluation of the structural integrity and extracellular matrix components of tracheal allografts following cyclical decellularization techniques: comparison of three protocols.

    PubMed

    Haykal, Siba; Soleas, John P; Salna, Michael; Hofer, Stefan O P; Waddell, Thomas K

    2012-08-01

    Tracheal reconstruction is indicated in cases of malignancy, traumatic injury, and subglottic or tracheal stenosis. Recent progress in airway transplantation has provided renewed optimism for potential solutions for defects involving more than half of the tracheal length in adults or one-third of the tracheal length in children. Biologic scaffolds derived from decellularized tissues and organs have shown great promise in tracheal allotransplantation, and cyclical decellularization techniques have been hypothesized as abrogating the need for immunosuppressive therapy. In this study, we performed a direct comparison of three decellularization protocols (Protocols A, B, and C) previously described in the literature, two of which were described in tracheal tissue (Protocols A and B). We concentrated on the immunogenicity within the epithelium and mucosa, quantified and qualified the extracellular matrix (ECM) components, and performed compliance measurements on large circumferential decellularized tracheal scaffolds following cyclical decellularization techniques using all three protocols. Quantitative measurements of glycosaminoglycans (GAGs) showed a significant decrease in the mucosal component following 17 cycles of all 3 protocols as well as a significant decrease of GAGs in the cartilaginous component following cycles 1, 9, and 17 of Protocol A and cycle 17 of Protocol C. Compliance measurements were also shown to be different between the protocols, with grafts becoming more compliant at physiologic pressures after cyclical decellularization with Protocols A and B and slightly less compliant but remaining similar to native trachea using Protocol C. Positive staining for anti-major histocompatibility complex Class I (anti-MHCI) and anti-MHCII remained within the submucosal glandular components despite multiple cycles of decellularization using all three protocols. This study illustrated that there are significant differences in ECM composition and resultant

  15. Evaluation of physiological risk factors, oxidant-antioxidant imbalance, proteolytic and genetic variations of matrix metalloproteinase-9 in patients with pressure ulcer

    PubMed Central

    Latifa, Khlifi; Sondess, Sahli; Hajer, Graiet; Manel, Ben-Hadj-Mohamed; Souhir, Khelil; Nadia, Bouzidi; Abir, Jaballah; Salima, Ferchichi; Abdelhedi, Miled

    2016-01-01

    Pressure ulcer (PU) remains a common worldwide problem in all health care settings, it is synonymous with suffering. PU is a complex disease that is dependent on a number of interrelated factors. It involves multiple mechanisms such as physiological risk factors, chronic inflammation, oxidant–antioxidant imbalance and proteolytic attack on extracellular matrix by matrix metalloproteinases (MMP). Therefore, we propose that these wounds lead to molecular variations that can be detected by assessing biomarkers. In this study, we aimed to evaluate the major clinical elements and biological scars in Tunisian patients suffering from PU. Consistently, non-healing wound remains a challenging clinical problem. The complex challenges of the wound environment, involving nutrient deficiencies, bacterial infection, as well as the critical role played by inflammatory cells, should be considered because of their negative impact on wound healing. In addition, an imbalance between pro-oxidants and antioxidant systems seems to be more aggravated in patients with PU compared to healthy subjects. Of interest, this study provides further evidence to support a core role of the biological activity of MMP-9 in the pathogenesis of PU and indicates that the MMP9-1562 C/T (rs 3918242) functional polymorphism is associated with protection against this disease. PMID:27405842

  16. Evaluation of physiological risk factors, oxidant-antioxidant imbalance, proteolytic and genetic variations of matrix metalloproteinase-9 in patients with pressure ulcer.

    PubMed

    Latifa, Khlifi; Sondess, Sahli; Hajer, Graiet; Manel, Ben-Hadj-Mohamed; Souhir, Khelil; Nadia, Bouzidi; Abir, Jaballah; Salima, Ferchichi; Abdelhedi, Miled

    2016-07-11

    Pressure ulcer (PU) remains a common worldwide problem in all health care settings, it is synonymous with suffering. PU is a complex disease that is dependent on a number of interrelated factors. It involves multiple mechanisms such as physiological risk factors, chronic inflammation, oxidant-antioxidant imbalance and proteolytic attack on extracellular matrix by matrix metalloproteinases (MMP). Therefore, we propose that these wounds lead to molecular variations that can be detected by assessing biomarkers. In this study, we aimed to evaluate the major clinical elements and biological scars in Tunisian patients suffering from PU. Consistently, non-healing wound remains a challenging clinical problem. The complex challenges of the wound environment, involving nutrient deficiencies, bacterial infection, as well as the critical role played by inflammatory cells, should be considered because of their negative impact on wound healing. In addition, an imbalance between pro-oxidants and antioxidant systems seems to be more aggravated in patients with PU compared to healthy subjects. Of interest, this study provides further evidence to support a core role of the biological activity of MMP-9 in the pathogenesis of PU and indicates that the MMP9-1562 C/T (rs 3918242) functional polymorphism is associated with protection against this disease.

  17. Sync Matrix

    SciTech Connect

    Metz, William C.; Metz, W. Chris; Mitrani, Jacques E.; Hewett, Jr., Paul L.; Jones, Christopher A.

    2004-12-31

    Sync Matrix provides a graphic display of the relationships among all of the response activities of each jurisdiction. This is accomplished through software that organizes and displays the activities by jurisdiction, function, and time for easy review and analysis. The software can also integrate the displays of multiple jurisdictions to allow examination of the total response.

  18. SLIM--An Early Work Revisited

    SciTech Connect

    Chao, Alex; /SLAC

    2008-07-25

    An early, but at the time illuminating, piece of work on how to deal with a general, linearly coupled accelerator lattice is revisited. This work is based on the SLIM formalism developed in 1979-1981.

  19. McLean's second variation formula revisited

    NASA Astrophysics Data System (ADS)

    Lê, Hông Vân; Vanžura, Jiří

    2017-03-01

    We revisit McLean's second variation formulas for calibrated submanifolds in exceptional geometries, and correct his formulas concerning associative submanifolds and Cayley submanifolds, using a unified treatment based on the (relative) calibration method and Harvey-Lawson's identities.

  20. Mele-Maat Revisited.

    ERIC Educational Resources Information Center

    Stone, James C.

    This study provides an evaluation of the quality of immersion instruction in English as a second language in the Mele-Maat School, an English-medium, British-administered Polynesian school in Vanuatu, an independent South Pacific nation. The study consisted of one year of baseline data gathering and a second year for replication using standardized…

  1. Part Singing Revisited.

    ERIC Educational Resources Information Center

    Junda, Mary Ellen

    1997-01-01

    Maintains that children's success with drones, responsorial singing, and ostinatos in the primary grades can lead naturally to the singing of polyphony and homophony in the upper elementary grades. Recommends teachers using age-appropriate materials, teaching sequentially, and evaluating each instructional step. Lists national standards related to…

  2. The Protestant Establishment Revisited

    ERIC Educational Resources Information Center

    Baltzell, E. Digby

    1976-01-01

    The author's book, "The Protestant Establishment: Aristocracy and Caste in America", is highly critical of the WASP (White-Anglo-Saxon-Protestant) establishment and proposed the development and need for some sort of upper-class ruling-group. Here is a re-evaluation of his book, now thirteen years old, by the author. (Author/RK)

  3. Performance Measurement Revisited

    ERIC Educational Resources Information Center

    Axford, H. William

    1973-01-01

    Performance measurement, through unit-cost study programs, can be a step toward evaluating the value of systems. This article reports the application of unit-cost studies in technical service functions at a large state university, and presents three tables for labor costs in terms of minutes and dollars per volume. (4 references) (Author/SJ)

  4. Project Bluebook Revisited.

    ERIC Educational Resources Information Center

    Lockwood, Jeffrey F.

    1990-01-01

    Described is an interdisciplinary unit on pseudoscience which combines interest in unidentified flying objects (UFO's), physics, astronomy, art, and english composition. The different phases of the lesson, assignments, and evaluation are discussed. A list of books available on UFOs is provided. (CW)

  5. Creativity and Intuition Revisited

    ERIC Educational Resources Information Center

    Dollinger, Stephen J.; Palaskonis, Dimitra G.; Pearson, Jodi L.

    2004-01-01

    This study used the recently revised Myers Briggs Type Indicator (MBTI) and a variety of validated creativity measures to replicate a classic finding--that sensing-intuition predicts creativity--and to evaluate whether the other MBTI scales add to the prediction of creativity. 94 undergraduates completed the MBTI (form M self-scorable) and…

  6. Leadership Giftedness: Models Revisited.

    ERIC Educational Resources Information Center

    Roach, Adelma A.; Wyman, Leisy T.; Brookes, Heather; Chavez, Christina; Heath, Shirley Brice; Valdes, Guadalupe

    1999-01-01

    A decade-long study in underserved and at-risk communities evaluated young people identified as leaders within out-of-school youth organizations. Findings revealed that emerging youth leadership differs from established measures and leadership theories drawn from adults with a greater emphasis on how leadership happens, rather than who leaders…

  7. The Fresnel Integrals Revisited

    ERIC Educational Resources Information Center

    Chen, Hongwei

    2009-01-01

    This note presents another elementary method to evaluate the Fresnel integrals. It is interesting to see that this technique is also strong enough to capture a number of pairs of parameter integrals. The main ingredients of the method are the consideration of some related derivatives and linear differential equations.

  8. Histological evaluation of mineral trioxide aggregate and enamel matrix derivative combination in direct pulp capping: An in vivo study

    PubMed Central

    Bollu, Indira Priyadarshini; Velagula, L. Deepa; Bolla, Nagesh; Kumar, K. Kiran; Hari, Archana; Thumu, Jayaprakash

    2016-01-01

    Aim: The aim of this study is to evaluate the response of human pulp tissue to mineral trioxide aggregate (MTA), Emdogain (EMD), and combination of MTA/EMD. Materials and Methods: This study was performed on sixty intact first and second premolars of human maxillary and mandibular teeth. A standard pulpal exposure was done on all the teeth and was divided into three groups of twenty teeth each and was capped with MTA, EMD, and MTA/EMD combination. The final restoration was done with resin-modified glass ionomer cement. The teeth were then extracted on the 15th or 45th day and histological evaluation done. Results: Differences in inflammatory response and thickness of dentin bridge formation of the exposed pulp to the three different groups were statistically evaluated using Chi-square and Mann–Whitney tests and were found to be significant. No significant difference was found between MTA/EMD and MTA in terms of calcified bridge formation and pulp inflammatory response to the capping materials. Conclusions: MTA and MTA/EMD combination produced a better quality hard tissue response compared with the use of EMD. PMID:27994315

  9. Occupational health and safety: Designing and building with MACBETH a value risk-matrix for evaluating health and safety risks

    NASA Astrophysics Data System (ADS)

    Lopes, D. F.; Oliveira, M. D.; Costa, C. A. Bana e.

    2015-05-01

    Risk matrices (RMs) are commonly used to evaluate health and safety risks. Nonetheless, they violate some theoretical principles that compromise their feasibility and use. This study describes how multiple criteria decision analysis methods have been used to improve the design and the deployment of RMs to evaluate health and safety risks at the Occupational Health and Safety Unit (OHSU) of the Regional Health Administration of Lisbon and Tagus Valley. ‘Value risk-matrices’ (VRMs) are built with the MACBETH approach in four modelling steps: a) structuring risk impacts, involving the construction of descriptors of impact that link risk events with health impacts and are informed by scientific evidence; b) generating a value measurement scale of risk impacts, by applying the MACBETH-Choquet procedure; c) building a system for eliciting subjective probabilities that makes use of a numerical probability scale that was constructed with MACBETH qualitative judgments on likelihood; d) and defining a classification colouring scheme for the VRM. A VRM built with OHSU members was implemented in a decision support system which will be used by OHSU members to evaluate health and safety risks and to identify risk mitigation actions.

  10. Hantush Well Function revisited

    NASA Astrophysics Data System (ADS)

    Veling, E. J. M.; Maas, C.

    2010-11-01

    SummaryIn this paper, we comment on some recent numerical and analytical work to evaluate the Hantush Well Function. We correct an expression found in a Comment by Nadarajah [Nadarajah, S., 2007. A comment on numerical evaluation of Theis and Hantush-Jacob well functions. Journal of Hydrology 338, 152-153] to a paper by Prodanoff et al. [Prodanoff, J.A., Mansur, W.J., Mascarenhas, F.C.B., 2006. Numerical evaluation of Theis and Hantush-Jacob well functions. Journal of Hydrology 318, 173-183]. We subsequently derived another analytic representation based on a generalized hypergeometric function in two variables and from the hydrological literature we cite an analytic representation by Hunt [Hunt, B., 1977. Calculation of the leaky aquifer function. Journal of Hydrology 33, 179-183]. We have implemented both representations and compared the results. Using a convergence accelerator Hunt's representation of Hantush Well Function is efficient and accurate. While checking our implementations we found that Bear's table of the Hantush Well Function [Bear, J., 1979. Hydraulics of Groundwater. McGraw-Hill, New York, Tables 8-6] contains a number of typographical errors that are not present in the original table published by Hantush [Hantush, M.S., 1956. Analysis of data from pumping tests in leaky aquifers. Transactions, American Geophysical Union 37, 702-714]. Finally, we offer a very fast approximation with a maximum relative error of 0.0033 for the parameter range in the table given by Bear.

  11. Experimental bone defect healing with xenogenic demineralized bone matrix and bovine fetal growth plate as a new xenograft: radiological, histopathological and biomechanical evaluation.

    PubMed

    Bigham, A S; Dehghani, S N; Shafiei, Z; Nezhad, S Torabi

    2009-02-01

    The following study was designed to evaluate xenogenic bovine demineralized bone matrix (DBM) and new xenograft (Bovine fetal growth plate) effects on bone healing process. Twenty male White New Zealand rabbits were used in this study. In group I (n = 10) the defect was filled by xenogenic DBM and in group II (n = 10) the defect was filled by a segment of bovine fetal growth plate and was fixed by cercelage wire. Radiological, histopathological, and biomechanical evaluations were performed blindly and results scored and analyzed statistically. Statistical tests did not support significant differences between two groups radiographically (P > 0.05). There was a significant difference for union at the 28th postoperative radiologically (P < 0.05). Xenograft was superior to DBM group at the 28th postoperative day for radiological union (P < 0.03). Histopathological and biomechanical evaluation revealed no significant differences between two groups. In conclusion, the results of this study indicate that satisfactory healing occurred in rabbit radius defect filled with xenogenic bovine DBM and xenogenic bovine fetal growth plate. Complications were not identified and healing was faster in two grafting groups.

  12. Evaluation of Heterogeneous Options: Effects of MgO versus UO2 Matrix Selection for Minor Actinide Targets in a Sodium Fast Reactor

    SciTech Connect

    M. Pope; S. Bays; R. Ferrer

    2008-03-01

    The primary focus of this work was to compare MgO with UO2 as target matrix material options for burning minor actinides in a transmutation target within a sodium fast reactor. This analysis compared the transmutation performance of target assemblies having UO2 matrix to those having specifically MgO inert matrix.

  13. Monitoring phospholipids for assessment of ion enhancement and ion suppression in ESI and APCI LC/MS/MS for chlorpheniramine in human plasma and the importance of multiple source matrix effect evaluations.

    PubMed

    Ismaiel, Omnia A; Halquist, Matthew S; Elmamly, Magda Y; Shalaby, Abdalla; Thomas Karnes, H

    2008-11-15

    Biological matrix effects are a source of significant errors in both electrospray (ESI) and atmospheric pressure chemical ionization (APCI) LC/MS. Glycerophosphocholines (GPChos) and 2-lyso-glycerophosphocholines (2-lyso GPChos) are known to fragment to form ions at m/z 184 and m/z 104, respectively. Phospholipids were used as markers to evaluate matrix effects resulting in both ion suppression and enhancement using ESI and APCI modes in the determination of chlorpheniramine in human plasma. Results revealed that GPChos and 2-lyso GPChos demonstrated very low ionization efficiency in the APCI mode, post-column infusion experiments were performed to confirm that suppression and enhancement matrix ionization effects coincided with the elution profiles of the phospholipids. The mean matrix effect for chlorpheniramine using APCI was 75% less than the mean matrix effect in ESI, making APCI the ionization method of choice initially even though the absolute response was lower than in the ESI mode. The resulting APCI method showed acceptable results according to the FDA guidelines; however, a multiple source relative matrix effects study demonstrated variability. It was concluded that an absolute matrix effects study in one source of biological fluid may be not sufficient to ensure the validity of the method in various sources of matrix. In order to obviate the multiple matrix source variability, we employed an isotopically labeled internal standard for quantification of chlorpheniramine in the ESI mode. An additional validation was completed with the use of chlorpheniramine-d(6) as the internal standard. This method met all acceptance criteria according to the FDA guidelines, and the relative matrix affects study was successful.

  14. Granger causality revisited.

    PubMed

    Friston, Karl J; Bastos, André M; Oswal, Ashwini; van Wijk, Bernadette; Richter, Craig; Litvak, Vladimir

    2014-11-01

    This technical paper offers a critical re-evaluation of (spectral) Granger causality measures in the analysis of biological timeseries. Using realistic (neural mass) models of coupled neuronal dynamics, we evaluate the robustness of parametric and nonparametric Granger causality. Starting from a broad class of generative (state-space) models of neuronal dynamics, we show how their Volterra kernels prescribe the second-order statistics of their response to random fluctuations; characterised in terms of cross-spectral density, cross-covariance, autoregressive coefficients and directed transfer functions. These quantities in turn specify Granger causality - providing a direct (analytic) link between the parameters of a generative model and the expected Granger causality. We use this link to show that Granger causality measures based upon autoregressive models can become unreliable when the underlying dynamics is dominated by slow (unstable) modes - as quantified by the principal Lyapunov exponent. However, nonparametric measures based on causal spectral factors are robust to dynamical instability. We then demonstrate how both parametric and nonparametric spectral causality measures can become unreliable in the presence of measurement noise. Finally, we show that this problem can be finessed by deriving spectral causality measures from Volterra kernels, estimated using dynamic causal modelling.

  15. Interlaminar G(IIc) evaluation of toughened-resin matrix composites using the end-notched flexure test

    NASA Technical Reports Server (NTRS)

    Murri, G. B.; Obrien, T. K.

    1985-01-01

    The usefulness of the end-notched flexure (ENF) test for measuring G(IIc) for toughened composites was evaluated. Calculations were made using the measured flexural compliance from the ENF test and the measured axial modulus. Tests were conducted on three different composite materials, using laminates with two different span lengths and insert sizes. The error associated with neglecting nonlinear terms in the displacement-curvature relationship was analyzed to demonstrate the influence of specimen geometry on G(IIc) measurement. It is concluded that G(IIc) measurement may vary with the method of calculation, span length, or insert thickness, but these effects are minor compared to the large differences in measurements obtained for different materials. Hence, the ENF test is a valid one for screening materials for improvements in interlaminar shear fracture toughness.

  16. Process and outcome constructs for evaluating community-based participatory research projects: a matrix of existing measures.

    PubMed

    Sandoval, Jennifer A; Lucero, Julie; Oetzel, John; Avila, Magdalena; Belone, Lorenda; Mau, Marjorie; Pearson, Cynthia; Tafoya, Greg; Duran, Bonnie; Iglesias Rios, Lisbeth; Wallerstein, Nina

    2012-08-01

    Community-based participatory research (CBPR) has been widely used in public health research in the last decade as an approach to develop culturally centered interventions and collaborative research processes in which communities are directly involved in the construction and implementation of these interventions and in other application of findings. Little is known, however, about CBPR pathways of change and how these academic-community collaborations may contribute to successful outcomes. A new health CBPR conceptual model (Wallerstein N, Oetzel JG, Duran B et al. CBPR: What predicts outcomes? In: Minkler M, Wallerstein N (eds). Communication Based Participatory Research, 2nd edn. San Francisco, CA: John Wiley & Co., 2008) suggests that relationships between four components: context, group dynamics, the extent of community-centeredness in intervention and/or research design and the impact of these participatory processes on CBPR system change and health outcomes. This article seeks to identify instruments and measures in a comprehensive literature review that relates to these distinct components of the CBPR model and to present them in an organized and indexed format for researcher use. Specifically, 258 articles were identified in a review of CBPR (and related) literature from 2002 to 2008. Based on this review and from recommendations of a national advisory board, 46 CBPR instruments were identified and each was reviewed and coded using the CBPR logic model. The 46 instruments yielded 224 individual measures of characteristics in the CBPR model. While this study does not investigate the quality of the instruments, it does provide information about reliability and validity for specific measures. Group dynamics proved to have the largest number of identified measures, while context and CBPR system and health outcomes had the least. Consistent with other summaries of instruments, such as Granner and Sharpe's inventory (Granner ML, Sharpe PA. Evaluating community

  17. Evaluation of Effecting Parameters on Optimum Arrangement of Urban Land Uses and Assessment of Their Compatibility Using Adjacency Matrix

    NASA Astrophysics Data System (ADS)

    Vaezi, S.; Mesgari, M. S.; Kaviary, F.

    2015-12-01

    Todays, stability of human life is threatened by a set of parameters. So sustainable urban development theory is introduced after the stability theory to protect the urban environment. In recent years, sustainable urban development gains a lot of attraction by different sciences and totally becomes a final target for urban development planners and managers to use resources properly and to establish a balanced relationship among human, community, and nature. Proper distribution of services for decreasing spatial inequalities, promoting the quality of living environment, and approaching an urban stability requires an analytical understanding of the present situation. Understanding the present situation is the first step for making a decision and planning effectively. This paper evaluates effective parameters affecting proper arrangement of land-uses using a descriptive-analytical method, to develop a conceptual framework for understanding of the present situation of urban land-uses, based on the assessment of their compatibility. This study considers not only the local parameters, but also spatial parameters are included in this study. The results indicate that land-uses in the zone considered here are not distributed properly. Considering mentioned parameters and distributing service land-uses effectively cause the better use of these land-uses.

  18. Clinical and radiographic evaluation of copolymerized Polylactic/polyglycolic acids as a bone filler in combination with a cellular dermal matrix graft around immediate implants

    PubMed Central

    Soliman, Mahitab M.; Zaki, Azza Abdulrahman; El Gazaerly, Hanaa Mohamed; Shemmrani, Ammar Al; Sorour, Abd El Latif

    2014-01-01

    Objective This study was conducted to evaluate clinically and radiographically the use of a cellular dermal matrix allograft (Alloderm) in combination with PLA/PGA (Fisiograft) around immediate implants. Materials and Methods Fourteen patients were included in this study, three patients received two implants, total of seventeen implants were placed. Periapical radiographs and orthopantomographs were taken. The selected teeth were extracted atraumatically after the reflection of full thickness flaps. One-piece Zimmer implants were placed immediately into the sockets. Weeks from implantation, radiographic evaluation was made at 6 Fisiograft in powder form was placed in the osseous defects around the implants. The implants were immediately restored with provisional crowns free from occlusion. Patients were clinically evaluated at 3, 6, and 14 months after loading which was done after 6 weeks from implantation. Radiographic evaluation was made at 6 and 14 months from implant placement. Results showed that immediate implantation was successful in sixteen out of seventeen implants, clinical parameters regarding plaque index, gingival index, there was a slight decrease through the follow-up periods from 3 to 14 months but it was non-significant, while there was a significant decrease in the probing depth. Radiographically there was a significant increase in the bone density from 6 to 14 months post loading, while the vertical bone defect was significantly decreased. The fisiograft functioned well as space maker and scaffolding material. The Alloderm performed well as a membrane to be used in association with immediate implants and it has a good potentiality for increasing the width of the keratinized gingiva, which is an important feature for implant esthetics. Conclusion the combination technique between the bone graft and the membrane proved to be successful to overcome dehiscence and osseous defects around immediate implants. PMID:25780357

  19. Evaluation of dermal-epidermal skin equivalents ('composite-skin') of human keratinocytes in a collagen-glycosaminoglycan matrix(Integra artificial skin).

    PubMed

    Kremer, M; Lang, E; Berger, A C

    2000-09-01

    Integra artificial skin (Integra LifeSciences Corp., Plainsboro, NJ, USA) is a dermal template consisting of bovine collagen, chondroitin-6-sulphate and a silastic membrane manufactured as Integra. This product has gained widespread use in the clinical treatment of third degree burn wounds and full thickness skin defects of different aetiologies. The product was designed to significantly reduce the time needed to achieve final wound closure in the treatment of major burn wounds, to optimise the sparse autologous donor skin resources and to improve the durable mechanical quality of the skin substitute. The clinical procedure requires two stages. The first step creates a self neodermis, the second creates a self epidermis on the neodermis. However, it is desirable to cover major burn wounds early in a single step by a skin substitute consisting of a dermal equivalent seeded in vitro with autologous keratinocytes ('composite-skin') out of which a full thickness skin develops in vivo.The goal of this experimental study was to develop a method to integrate human keratinocytes in homogeneous distribution and depth into Integra Artificial Skin. The seeded cell-matrix composites were grafted onto athymic mice in order to evaluate their potential to reconstitute a human epidermis in vivo. We were able to demonstrate that the inoculated human keratinocytes reproducibly displayed a homogeneous pattern of distribution, adherence, proliferation and confluence. The cell-matrix composites grafted in this model exhibited good wound adherence, complete healing, minor wound contraction and had the potential to reconstitute an elastic, functional and durable human skin. Histologically we were able to show that the inoculated human keratinocytes in vivo colonised the matrix in a histomorphologically characteristic epidermal pattern (keratomorula, keratinocyte bubbling) and developed a persisting, stratified, keratinising epidermis which immunohistologically proved to be of human

  20. Durability Evaluation of a Thin Film Sensor System With Enhanced Lead Wire Attachments on SiC/SiC Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Lei, Jih-Fen; Kiser, J. Douglas; Singh, Mrityunjay; Cuy, Mike; Blaha, Charles A.; Androjna, Drago

    2000-01-01

    An advanced thin film sensor system instrumented on silicon carbide (SiC) fiber reinforced SiC matrix ceramic matrix composites (SiC/SiC CMCs), was evaluated in a Mach 0.3 burner rig in order to determine its durability to monitor material/component surface temperature in harsh environments. The sensor system included thermocouples in a thin film form (5 microns thick), fine lead wires (75 microns diameter), and the bonds between these wires and the thin films. Other critical components of the overall system were the heavy, swaged lead wire cable (500 microns diameter) that contained the fine lead wires and was connected to the temperature readout, and ceramic attachments which were bonded onto the CMCs for the purpose of securing the lead wire cables, The newly developed ceramic attachment features a combination of hoops made of monolithic SiC or SiC/SiC CMC (which are joined to the test article) and high temperature ceramic cement. Two instrumented CMC panels were tested in a burner rig for a total of 40 cycles to 1150 C (2100 F). A cycle consisted of rapid heating to 1150 C (2100 F), a 5 minute hold at 1150 C (2100 F), and then cooling down to room temperature in 2 minutes. The thin film sensor systems provided repeatable temperature measurements for a maximum of 25 thermal cycles. Two of the monolithic SiC hoops debonded during the sensor fabrication process and two of the SiC/SiC CMC hoops failed during testing. The hoops filled with ceramic cement, however, showed no sign of detachment after 40 thermal cycle test. The primary failure mechanism of this sensor system was the loss of the fine lead wire-to-thin film connection, which either due to detachment of the fine lead wires from the thin film thermocouples or breakage of the fine wire.

  1. Parmacokinetic evaluation of ibuprofen controlled release matrix tablets using hydrophilic Eudragit® polymer and co-excipients.

    PubMed

    Bakhsh, Sattar; Khan, Gul Majid; Menaa, Farid; Khan, Barkat Ali

    2015-09-01

    The present study was conducted to formulate controlled release dosage forms containing Ibuprofen with Eudragit® S 100 polymer. The tablets were formulated at three different ratios with the polymer to investigate the effect of different concentrations of polymer on in vitro drug release patterns/kinetics and in vivo absorption/pharmacokinetics. Pre-formulation studies were conducted including bulk density, tapped density, compressibility index, Hausner ratio and angle of repose. In vitro studies were conducted using phosphate buffer (pH 7.4) as dissolution medium. In vivo performance was evaluated using albino rabbits. Physico-chemical characteristics (i.e. dimensional tests, weight variation, hardness, friability and drug content determination) fell in the USP acceptable limits. The compressibility index was found to range between 12.02 ± 0.01% and 18.66 ± 0.03%, the Hausner ratio varied between 1.02 ± 0.01 and 1.19 ± 0.10 and the angle of repose ranged from 15.19 ± 0.01 to 24.52 ± 0.10, all indicating better flow properties than the bulk-reference standard. Both bulk and tapped densities also fell in the USP acceptable range. Ibuprofen market tablets showed Tmax of 2.1 ± 0.4h, which was significantly (P-value <0.05) lower compared to that of the reference standard (i.e. 4.09 ± 1.3h). Ibuprofen test formulation has a half-life (t1/2) of 16.9 ± 2.5h, which was significantly (P-value<0.001) higher compared to that of the reference standard (i.e. 9.23 ± 2.9h). Eudragit® S 100 polymers can be used efficiently to develop directly compressed prolonged release tablets.

  2. Evaluation of Matrix-Assisted Laser Desorption Ionization−Time of Flight Mass Spectrometry for Identification of Mycobacterium species, Nocardia species, and Other Aerobic Actinomycetes

    PubMed Central

    Buckwalter, S. P.; Olson, S. L.; Connelly, B. J.; Lucas, B. C.; Rodning, A. A.; Walchak, R. C.; Deml, S. M.; Wohlfiel, S. L.

    2015-01-01

    The value of matrix-assisted laser desorption ionization−time of flight mass spectrometry (MALDI-TOF MS) for the identification of bacteria and yeasts is well documented in the literature. Its utility for the identification of mycobacteria and Nocardia spp. has also been reported in a limited scope. In this work, we report the specificity of MALDI-TOF MS for the identification of 162 Mycobacterium species and subspecies, 53 Nocardia species, and 13 genera (totaling 43 species) of other aerobic actinomycetes using both the MALDI-TOF MS manufacturer's supplied database(s) and a custom database generated in our laboratory. The performance of a simplified processing and extraction procedure was also evaluated, and, similar to the results in an earlier literature report, our viability studies confirmed the ability of this process to inactivate Mycobacterium tuberculosis prior to analysis. Following library construction and the specificity study, the performance of MALDI-TOF MS was directly compared with that of 16S rRNA gene sequencing for the evaluation of 297 mycobacteria isolates, 148 Nocardia species isolates, and 61 other aerobic actinomycetes isolates under routine clinical laboratory working conditions over a 6-month period. MALDI-TOF MS is a valuable tool for the identification of these groups of organisms. Limitations in the databases and in the ability of MALDI-TOF MS to rapidly identify slowly growing mycobacteria are discussed. PMID:26637381

  3. DROMO propagator revisited

    NASA Astrophysics Data System (ADS)

    Urrutxua, Hodei; Sanjurjo-Rivo, Manuel; Peláez, Jesús

    2016-01-01

    In the year 2000 an in-house orbital propagator called DROMO (Peláez et al. in Celest Mech Dyn Astron 97:131-150, 2007. doi: 10.1007/s10569-006-9056-3) was developed by the Space Dynamics Group of the Technical University of Madrid, based in a set of redundant variables including Euler-Rodrigues parameters. An original deduction of the DROMO propagator is carried out, underlining its close relation with the ideal frame concept introduced by Hansen (Abh der Math-Phys Cl der Kon Sachs Ges der Wissensch 5:41-218, 1857). Based on the very same concept, Deprit (J Res Natl Bur Stand Sect B Math Sci 79B(1-2):1-15, 1975) proposed a formulation for orbit propagation. In this paper, similarities and differences with the theory carried out by Deprit are analyzed. Simultaneously, some improvements are introduced in the formulation, that lead to a more synthetic and better performing propagator. Also, the long-term effect of the oblateness of the primary is studied in terms of DROMO variables, and new numerical results are presented to evaluate the performance of the method.

  4. Classical galactosaemia revisited.

    PubMed

    Bosch, Annet M

    2006-08-01

    Classical galactosaemia (McKusick 230400) is an: autosomal recessive disorder of galactose metabolism, caused by a deficiency of the enzyme galactose-1-phosphate uridyltransferase (GALT; EC 2.7.712). Most patients present in the neonatal period, after ingestion of galactose, with jaundice, hepatosplenomegaly, hepatocellular insufficiency, food intolerance, hypoglycaemia, renal tubular dysfunction, muscle hypotonia, sepsis and cataract. The gold standard for diagnosis of classical galactosaemia is measurement of GALT activity in erythrocytes. Gas-chromatographic determination of urinary sugars and sugar alcohols demonstrates elevated concentrations of galactose and galactitol. The only therapy for patients with classical galactosaemia is a galactose-restricted diet, and initially all galactose must be removed from the diet as soon as the diagnosis is suspected. After the neonatal period, a lactose-free diet is advised in most countries, without restriction of galactose-containing fruit and vegetables. In spite of the strict diet, long-term complications such as retarded mental development, verbal dyspraxia, motor abnormalities and hypergonadotrophic hypogonadism are frequently seen in patients with classical galactosaemia. It has been suggested that these complications may result from endogenous galactose synthesis or from abnormal galactosylation. Novel therapeutic strategies, aiming at the prevention of galactose 1-phosphate production, should be developed. In the meantime, the follow-up protocol for patients with GALT deficiency should focus on early detection, evaluation and, if possible, early intervention in problems of motor, speech and cognitive development.

  5. Coherence and Coreference Revisited

    PubMed Central

    KEHLER, ANDREW; KERTZ, LAURA; ROHDE, HANNAH; ELMAN, JEFFREY L.

    2011-01-01

    For more than three decades, research into the psycholinguistics of pronoun interpretation has argued that hearers use various interpretation ‘preferences’ or ‘strategies’ that are associated with specific linguistic properties of antecedent expressions. This focus is a departure from the type of approach outlined in Hobbs (1979), who argues that the mechanisms supporting pronoun interpretation are driven predominantly by semantics, world knowledge and inference, with particular attention to how these are used to establish the coherence of a discourse. On the basis of three new experimental studies, we evaluate a coherence-driven analysis with respect to four previously proposed interpretation biases—based on grammatical role parallelism, thematic roles, implicit causality, and subjecthood—and argue that the coherence-driven analysis can explain the underlying source of the biases and predict in what contexts evidence for each will surface. The results further suggest that pronoun interpretation is incrementally influenced by probabilistic expectations that hearers have regarding what coherence relations are likely to ensue, together with their expectations about what entities will be mentioned next, which, crucially, are conditioned on those coherence relations. PMID:22923856

  6. Universal Keplerian state transition matrix

    NASA Technical Reports Server (NTRS)

    Shepperd, S. W.

    1985-01-01

    A completely general method for computing the Keplerian state transition matrix in terms of Goodyear's universal variables is presented. This includes a new scheme for solving Kepler's problem which is a necessary first step to computing the transition matrix. The Kepler problem is solved in terms of a new independent variable requiring the evaluation of only one transcendental function. Furthermore, this transcendental function may be conveniently evaluated by means of a Gaussian continued fraction.

  7. Extracellular matrix remodeling: the common denominator in connective tissue diseases. Possibilities for evaluation and current understanding of the matrix as more than a passive architecture, but a key player in tissue failure.

    PubMed

    Karsdal, Morten A; Nielsen, Mette J; Sand, Jannie M; Henriksen, Kim; Genovese, Federica; Bay-Jensen, Anne-Christine; Smith, Victoria; Adamkewicz, Joanne I; Christiansen, Claus; Leeming, Diana J

    2013-03-01

    Increased attention is paid to the structural components of tissues. These components are mostly collagens and various proteoglycans. Emerging evidence suggests that altered components and noncoded modifications of the matrix may be both initiators and drivers of disease, exemplified by excessive tissue remodeling leading to tissue stiffness, as well as by changes in the signaling potential of both intact matrix and fragments thereof. Although tissue structure until recently was viewed as a simple architecture anchoring cells and proteins, this complex grid may contain essential information enabling the maintenance of the structure and normal functioning of tissue. The aims of this review are to (1) discuss the structural components of the matrix and the relevance of their mutations to the pathology of diseases such as fibrosis and cancer, (2) introduce the possibility that post-translational modifications (PTMs), such as protease cleavage, citrullination, cross-linking, nitrosylation, glycosylation, and isomerization, generated during pathology, may be unique, disease-specific biochemical markers, (3) list and review the range of simple enzyme-linked immunosorbent assays (ELISAs) that have been developed for assessing the extracellular matrix (ECM) and detecting abnormal ECM remodeling, and (4) discuss whether some PTMs are the cause or consequence of disease. New evidence clearly suggests that the ECM at some point in the pathogenesis becomes a driver of disease. These pathological modified ECM proteins may allow insights into complicated pathologies in which the end stage is excessive tissue remodeling, and provide unique and more pathology-specific biochemical markers.

  8. In vitro and in vivo evaluation of the effects of demineralized bone matrix or calcium sulfate addition to polycaprolactone-bioglass composites.

    PubMed

    Erdemli, O; Captug, O; Bilgili, H; Orhan, D; Tezcaner, A; Keskin, D

    2010-01-01

    The objective of this study was to improve the efficacy of polycaprolactone/bioglass (PCL/BG) bone substitute using demineralized bone matrix (DBM) or calcium sulfate (CS) as a third component. Composite discs involving either DBM or CS were prepared by compression moulding. Bioactivity of discs was evaluated by energy dispersive X-ray spectroscopy (ESCA) and scanning electron microscopy (SEM) following simulated body fluid incubation. The closest Calcium/Phosphate ratio to that of hydroxyl carbonate apatite crystals was observed for PCL/ BG/DBM group (1.53) after 15 day incubation. Addition of fillers increased microhardness and compressive modulus of discs. However, after 4 and 6-week PBS incubations, PCL/BG/DBM discs showed significant decrease in modulus (from 266.23 to 54.04 and 33.45 MPa, respectively) in parallel with its highest water uptakes (36.3 and 34.7%). Discs preserved their integrity with only considerable weight loss (7.5-14.5%) in PCL/BG/DBM group. In vitro cytotoxicity tests showed that all discs were biocompatible.

  9. Evaluation of two matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) systems for the identification of Candida species.

    PubMed

    Lacroix, C; Gicquel, A; Sendid, B; Meyer, J; Accoceberry, I; François, N; Morio, F; Desoubeaux, G; Chandenier, J; Kauffmann-Lacroix, C; Hennequin, C; Guitard, J; Nassif, X; Bougnoux, M-E

    2014-02-01

    Candida spp. are responsible for severe infections in immunocompromised patients and those undergoing invasive procedures. The accurate identification of Candida species is important because emerging species can be associated with various antifungal susceptibility spectra. Conventional methods have been developed to identify the most common pathogens, but have often failed to identify uncommon species. Several studies have reported the efficiency of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for the identification of clinically relevant Candida species. In this study, we evaluated two commercially available MALDI-TOF systems, Andromas™ and Bruker Biotyper™, for Candida identification in routine diagnosis. For this purpose, we investigated 1383 Candida isolates prospectively collected in eight hospital laboratories during routine practice. MALDI-TOF MS results were compared with those obtained using conventional phenotypic methods. Analysis of rDNA gene sequences with internal transcribed regions or D1-D2 regions is considered the reference standard for identification. Both MALDI-TOF MS systems could accurately identify 98.3% of the isolates at the species level (1359/1383 for Andromas™; 1360/1383 for Bruker Biotyper™) vs. 96.5% for conventional techniques. Furthermore, whereas conventional methods failed to identify rare or emerging species, these were correctly identified by MALDI-TOF MS. Both MALDI-TOF MS systems are accurate and cost-effective alternatives to conventional methods for mycological identification of clinically relevant Candida species and should improve the diagnosis of fungal infections as well as patient management.

  10. Chronotherapeutic drug delivery of Tamarind gum, Chitosan and Okra gum controlled release colon targeted directly compressed Propranolol HCl matrix tablets and in-vitro evaluation.

    PubMed

    Newton, A M J; Indana, V L; Kumar, Jatinder

    2015-08-01

    The main objective of this investigation is to develop a chronotherapeutic drug delivery of various natural polymers based colon targeted drug delivery systems to treat early morning sign in BP. The polymers such as Tamarind gum, Okra gum and Chitosan were used in the formulation design. A model drug Propranolol HCl was incorporated in the formulation in order to assess the controlled release and time dependent release potential of various natural polymers. A novel polymer Tamarind gum was extracted and used as a prime polymer in this study to prove the superiority of this polymer over other leading natural polymer. Propranolol HCl was used as a model drug which undergoes hepatic metabolism and witnesses the poor bioavailability. The matrix tablets of Propranolol HCl were prepared by direct compression. The tablets were evaluated for various quality control parameters and found to be within the limits. Carbopol 940 was used as an auxiliary polymer to modify the drug release and physicochemical characteristics of the tablets. The in vitro release studies were performed in 0.1N HCl for 1.5h, followed by pH 6.8 phosphate buffer for 2h and pH 7.4 phosphate buffer till maximum amount of drug release. The in vitro release profile of the formulations were fitted with various pharmacokinetic mathematical models and analyzed for release profile. The formulations prepared with Tamarind gum prolonged the release for an extended period of time compared to other polymer based formulation and showed an excellent compression characteristic.

  11. Application of the Dynamic Gastric Model to evaluate the effect of food on the drug release characteristics of a hydrophilic matrix formulation.

    PubMed

    Chessa, S; Huatan, H; Levina, M; Mehta, R Y; Ferrizzi, D; Rajabi-Siahboomi, A R

    2014-05-15

    Characterisation of the effect of food on the bio-performance of modified and extended release dosage forms can be very challenging due to the need to replicate the dynamic biochemical conditions of the human gut as well as the complex physical processing modalities under fed state. Classical compendial methods are useful for testing the quality of pharmaceutical dosage forms but typically have limitations in the accurate prediction of food-effect in-vivo. Preliminary evaluation of the Dynamic Gastric Model (DGM) shows that it can provide substantially more detailed mechanistic information on dosage form properties compared to conventional compendial testing. The potential effect of food on the drug release and physical properties of a hydrophilic matrix formulation containing a model drug, hydrochlorothiazide, was studied using compendial methods, bio-relevant media and the DGM (in combination with an off-line intestinal model). Whilst the compendial methods with biorelevant media provided good correlation with the dissolution rates observed using the DGM/intestinal model under simulated fasted state, the quantification of simulated fed state performance changes was much more challenging using the compendial methods. Classical compendial studies using biorelevant FeSSIF and FaSSIF media could not readily discern differences in dissolution performance under fasted and fed states; however, the DGM could detect significant changes in both physical properties as well as drug release performance under fed state processing.

  12. Evaluation of a Semiquantitative Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry Method for Rapid Antimicrobial Susceptibility Testing of Positive Blood Cultures.

    PubMed

    Jung, Jette S; Hamacher, Christina; Gross, Birgit; Sparbier, Katrin; Lange, Christoph; Kostrzewa, Markus; Schubert, Sören

    2016-11-01

    With the increasing prevalence of multidrug-resistant Gram-negative bacteria, rapid identification of the pathogen and its individual antibiotic resistance is crucial to ensure adequate antiinfective treatment at the earliest time point. Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry for the identification of bacteria directly from the blood culture bottle has been widely established; however, there is still an urgent need for new methods that permit rapid resistance testing. Recently, a semiquantitative MALDI-TOF mass spectrometry-based method for the prediction of antibiotic resistance was described. We evaluated this method for detecting nonsusceptibility against two β-lactam and two non-β-lactam antibiotics. A collection of 30 spiked blood cultures was tested for nonsusceptibility against gentamicin and ciprofloxacin. Furthermore, 99 patient-derived blood cultures were tested for nonsusceptibility against cefotaxime, piperacillin-tazobactam, and ciprofloxacin in parallel with MALDI-TOF mass spectrometry identification from the blood culture fluid. The assay correctly classified all isolates tested for nonsusceptibility against gentamicin and cefotaxime. One misclassification for ciprofloxacin nonsusceptibility and five misclassifications for piperacillin-tazobactam nonsusceptibility occurred. Identification of the bacterium and prediction of nonsusceptibility was possible within approximately 4 h.

  13. Structural and biological evaluation of lignin addition to simple and silver-doped hydroxyapatite thin films synthesized by matrix-assisted pulsed laser evaporation.

    PubMed

    Janković, A; Eraković, S; Ristoscu, C; Mihailescu Serban, N; Duta, L; Visan, A; Stan, G E; Popa, A C; Husanu, M A; Luculescu, C R; Srdić, V V; Janaćković, Dj; Mišković-Stanković, V; Bleotu, C; Chifiriuc, M C; Mihailescu, I N

    2015-01-01

    We report on thin film deposition by matrix-assisted pulsed laser evaporation of simple hydroxyapatite (HA) or silver (Ag) doped HA combined with the natural biopolymer organosolv lignin (Lig) (Ag:HA-Lig). Solid cryogenic target of aqueous dispersions of Ag:HA-Lig composite and its counterpart without silver (HA-Lig) were prepared for evaporation using a KrF* excimer laser source. The expulsed material was assembled onto TiO2/Ti substrata or silicon wafers and subjected to physical-chemical investigations. Smooth, uniform films adherent to substratum were observed. The chemical analyses confirmed the presence of the HA components, but also evidenced traces of Ag and Lig. Deposited HA was Ca deficient, which is indicative of a film with increased solubility. Recorded X-ray Diffraction patterns were characteristic for amorphous films. Lig presence in thin films was undoubtedly proved by both X-ray Photoelectron and Fourier Transform Infra-Red Spectroscopy analyses. The microbiological evaluation showed that the newly assembled surfaces exhibited an inhibitory activity both on the initial steps of biofilm forming, and on mature bacterial and fungal biofilm development. The intensity of the anti-biofilm activity was positively influenced by the presence of the Lig and/or Ag, in the case of Staphylococcus aureus, Pseudomonas aeruginosa and Candida famata biofilms. The obtained surfaces exhibited a low cytotoxicity toward human mesenchymal stem cells, being therefore promising candidates for fabricating implantable biomaterials with increased biocompatibility and resistance to microbial colonization and further biofilm development.

  14. Evaluation of VITEK Mass Spectrometry (MS), a Matrix-Assisted Laser Desorption Ionization Time-of-Flight MS System for Identification of Anaerobic Bacteria

    PubMed Central

    Lee, Wonmok; Kim, Myungsook; Yong, Dongeun; Jeong, Seok Hoon; Chong, Yunsop

    2015-01-01

    Background By conventional methods, the identification of anaerobic bacteria is more time consuming and requires more expertise than the identification of aerobic bacteria. Although the matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) systems are relatively less studied, they have been reported to be a promising method for the identification of anaerobes. We evaluated the performance of the VITEK MS in vitro diagnostic (IVD; 1.1 database; bioMérieux, France) in the identification of anaerobes. Methods We used 274 anaerobic bacteria isolated from various clinical specimens. The results for the identification of the bacteria by VITEK MS were compared to those obtained by phenotypic methods and 16S rRNA gene sequencing. Results Among the 249 isolates included in the IVD database, the VITEK MS correctly identified 209 (83.9%) isolates to the species level and an additional 18 (7.2%) at the genus level. In particular, the VITEK MS correctly identified clinically relevant and frequently isolated anaerobic bacteria to the species level. The remaining 22 isolates (8.8%) were either not identified or misidentified. The VITEK MS could not identify the 25 isolates absent from the IVD database to the species level. Conclusions The VITEK MS showed reliable identifications for clinically relevant anaerobic bacteria. PMID:25553283

  15. A clinical evaluation of guided tissue regeneration with a bioabsorbable matrix membrane combined with an allograft bone graft. A series of case reports.

    PubMed

    Harris, R J

    1997-06-01

    THE PURPOSE OF THIS STUDY was to evaluate the clinical effectiveness of a surgical technique in treating periodontal defects. The technique combined tetracycline treatment of a root planed root, grafting of the osseous defect with a demineralized freeze-dried bone allograft combined with tetracycline and the placement of a bioabsorbable matrix membrane, made of polylactic acid softened with citric acid ester. Thirty defects were treated in 27 patients. Statistically significant changes, as a result of the surgical procedure, were observed in marginal recession (mean: 0.5 mm), probing depth reductions (mean: 5.7 mm), and attachment level gain (mean: 5.2 mm). No statistically significant difference existed between the results in the furcation and non-furcation groups. The defects with probing depths > or = 10 mm had a greater mean probing depth reduction (7.4 mm) and mean attachment level improvement (7.2 mm) than the defects with < 10 mm probing depths (probing depth reduction 4.5 mm and attachment level gain 3.9 mm). The proposed surgical procedure seemed to be an effective method to treat periodontal defects.

  16. Development and evaluation of surface treatments to enhance the fiber-matrix adhesion in PAN-based carbon fiber/liquid crystal polymer composites

    SciTech Connect

    King, J.A.

    1989-01-01

    Various amine and electrochemical polymerization treatments were applied to comingled as-received AS4 carbon fiber/Liquid Crystal Polymer (LCP) fibers, and unidirectional composite plates were fabricated. Short beam shear (SBS) tests were conducted to determine the level of AS4 carbon fiber-LCP matrix adhesion present. The shear strength of the as-received AS4/LCP system was approximately 49 MPa (7.1 ksi). The as-received AS4 fiber-LCP matrix adhesion was determined to be reasonably good, at approximately 85 to 90% of a perfect bond as determined by micromechanics analyses. Several di/triamine treatments yielded approximately a 10 to 15% increase in fiber-matrix adhesion relative to the as-received AS4/LCP system. The electropolymerization of a polyphenylene oxide (PPO) coating on the AS4 surface enhanced the fiber-matrix adhesion by 14% relative to the as-received AS4/LCP system. Apparently, a good bond was established between the AS4 fiber, the PPO coating, and the LCP matrix. After these treatments, SEM observations of the shear failure surfaces indicated that a perfect fiber-matrix bond was obtained. That is, the failure location was in the LCP matrix material. A two-dimensional finite element analysis also supported this result. Thus, in order to improve the shear strength of the AS4/LCP system further, the shear strength of the LCP matrix material must be increased.

  17. Head Start Evaluation and Research Center. Progress Report of Research Studies 1966 to 1967. Document 1, Development of the Matrix Test.

    ERIC Educational Resources Information Center

    Zimiles, Herbert; Asch, Harvey

    A matrix test was devised to assess cognitive skills associated with inferential reasoning. The format of the test requires the subject to choose, from among four alternatives, a figure which is related to other given figures on the basis of appearance, content, or spatial position in the matrix. The test consists of three perceptual matching…

  18. Evaluation of Aerosol Mixing State Classes in the GISS Modele-matrix Climate Model Using Single-particle Mass Spectrometry Measurements

    NASA Technical Reports Server (NTRS)

    Bauer, Susanne E.; Ault, Andrew; Prather, Kimberly A.

    2013-01-01

    Aerosol particles in the atmosphere are composed of multiple chemical species. The aerosol mixing state, which describes how chemical species are mixed at the single-particle level, provides critical information on microphysical characteristics that determine the interaction of aerosols with the climate system. The evaluation of mixing state has become the next challenge. This study uses aerosol time-of-flight mass spectrometry (ATOFMS) data and compares the results to those of the Goddard Institute for Space Studies modelE-MATRIX (Multiconfiguration Aerosol TRacker of mIXing state) model, a global climate model that includes a detailed aerosol microphysical scheme. We use data from field campaigns that examine a variety of air mass regimens (urban, rural, and maritime). At all locations, polluted areas in California (Riverside, La Jolla, and Long Beach), a remote location in the Sierra Nevada Mountains (Sugar Pine) and observations from Jeju (South Korea), the majority of aerosol species are internally mixed. Coarse aerosol particles, those above 1 micron, are typically aged, such as coated dust or reacted sea-salt particles. Particles below 1 micron contain large fractions of organic material, internally-mixed with sulfate and black carbon, and few external mixtures. We conclude that observations taken over multiple weeks characterize typical air mass types at a given location well; however, due to the instrumentation, we could not evaluate mass budgets. These results represent the first detailed comparison of single-particle mixing states in a global climate model with real-time single-particle mass spectrometry data, an important step in improving the representation of mixing state in global climate models.

  19. Evaluation of aerosol mixing state classes in the GISS modelE-MATRIX climate model using single-particle mass spectrometry measurements

    NASA Astrophysics Data System (ADS)

    Bauer, Susanne E.; Ault, Andrew; Prather, Kimberly A.

    2013-09-01

    Aerosol particles in the atmosphere are composed of multiple chemical species. The aerosol mixing state, which describes how chemical species are mixed at the single-particle level, provides critical information on microphysical characteristics that determine the interaction of aerosols with the climate system. The evaluation of mixing state has become the next challenge. This study uses aerosol time-of-flight mass spectrometry (ATOFMS) data and compares the results to those of the Goddard Institute for Space Studies modelE-MATRIX (Multiconfiguration Aerosol TRacker of mIXing state) model, a global climate model that includes a detailed aerosol microphysical scheme. We use data from field campaigns that examine a variety of air mass regimens (urban, rural, and maritime). At all locations, polluted areas in California (Riverside, La Jolla, and Long Beach), a remote location in the Sierra Nevada Mountains (Sugar Pine) and observations from Jeju (South Korea), the majority of aerosol species are internally mixed. Coarse aerosol particles, those above 1 µm, are typically aged, such as coated dust or reacted sea-salt particles. Particles below 1 µm contain large fractions of organic material, internally mixed with sulfate and black carbon, and few external mixtures. We conclude that observations taken over multiple weeks characterize typical air mass types at a given location well; however, due to the instrumentation, we could not evaluate mass budgets. These results represent the first detailed comparison of single-particle mixing states in a global climate model with real-time single-particle mass spectrometry data, an important step in improving the representation of mixing state in global climate models.

  20. Analysis of Antiretrovirals in Single Hair Strands for Evaluation of Drug Adherence with Infrared-Matrix-Assisted Laser Desorption Electrospray Ionization Mass Spectrometry Imaging.

    PubMed

    Rosen, Elias P; Thompson, Corbin G; Bokhart, Mark T; Prince, Heather M A; Sykes, Craig; Muddiman, David C; Kashuba, Angela D M

    2016-01-19

    Adherence to a drug regimen can be a strong predictor of health outcomes, and validated measures of adherence are necessary at all stages of therapy from drug development to prescription. Many of the existing metrics of drug adherence (e.g., self-report, pill counts, blood monitoring) have limitations, and analysis of hair strands has recently emerged as an objective alternative. Traditional methods of hair analysis based on LC-MS/MS (segmenting strands at ≥1 cm length) are not capable of preserving a temporal record of drug intake at higher resolution than approximately 1 month. Here, we evaluated the detectability of HIV antiretrovirals (ARVs) in hair from a range of drug classes using infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) mass spectrometry imaging (MSI) with 100 μm resolution. Infrared laser desorption of hair strands was shown to penetrate into the strand cortex, allowing direct measurement by MSI without analyte extraction. Using optimized desorption conditions, a linear correlation between IR-MALDESI ion abundance and LC-MS/MS response was observed for six common ARVs with estimated limits of detection less than or equal to 1.6 ng/mg hair. The distribution of efavirenz (EFV) was then monitored in a series of hair strands collected from HIV infected, virologically suppressed patients. Because of the role hair melanin plays in accumulation of basic drugs (like most ARVs), an MSI method to quantify the melanin biomarker pyrrole-2,3,5-tricarboxylic acid (PTCA) was evaluated as a means of normalizing drug response between patients to develop broadly applicable adherence criteria.

  1. Evaluation of the effectiveness of enamel matrix derivative, bone grafts, and membrane in the treatment of mandibular Class II furcation defects.

    PubMed

    Jaiswal, Ritika; Deo, Vikas

    2013-01-01

    The combination of osseous graft with barrier membrane and enamel matrix protein derivative (EMD) has the potential to result in a synergistic effect. Therefore, the aim of this study was to evaluate the effectiveness of EMD in combination with demineralized freeze-dried bone allograft (BG) and bioresorbable membrane (Biomesh) in the treatment of human mandibular Class II furcation defects over a period of 12 months. Thirty patients with chronic periodontitis and a single Class II furcation defect on the buccal or lingual surface of mandibular teeth were included. The clinical parameters evaluated were probing pocket depth (PPD), horizontal probing depth (HPD), vertical relative attachment level (V-RAL), and relative gingival margin level (RGML). three groups were created based on treatment method: EMD + BG + guided tissue regeneration (GTR), BG + GTR, and open flap debridement (OFD). All three groups showed a statistically significant PPD reduction of 1.74 ± 1.00 mm, 0.81 ± 0.31 mm, and 0.46 ± 0.52 mm at 12 months postsurgery. EMD + BG + GTR showed a significantly greater PPD reduction compared with BG + GTR, as well as OFD. EMD + BG + GTR showed a statistically significant vertical clinical attachment gain of 2.12 ± 1.07 mm at 12 months compared with BG + GTR as well as OFD. Significant reductions in mean HPD were observed for EMD + BG + GTR (2.10 mm) as well as BG + GTR (1.5 mm). The number of Class II furcation defects that closed or converted to Class I was greatest for EMD + BG + GTR. It can be concluded that EMD + BG + GTR resulted in a statistically significant reduction of PPD, V-RAL gain, and a nonsignificantly greater reduction of HPD compared to BG + GTR.

  2. Development and evaluation of one-step TaqMan real-time reverse transcription-PCR assays targeting nucleoprotein, matrix, and hemagglutinin genes of equine influenza virus.

    PubMed

    Lu, Zhengchun; Chambers, Thomas M; Boliar, Saikat; Branscum, Adam J; Sturgill, Tracy L; Timoney, Peter J; Reedy, Stephanie E; Tudor, Lynn R; Dubovi, Edward J; Vickers, Mary Lynne; Sells, Stephen; Balasuriya, Udeni B R

    2009-12-01

    The objective of this study was to develop and evaluate new TaqMan real-time reverse transcription-PCR (rRT-PCR) assays by the use of the minor groove binding probe to detect a wide range of equine influenza virus (EIV) strains comprising both subtypes of the virus (H3N8 and H7N7). A total of eight rRT-PCR assays were developed, targeting the nucleoprotein (NP), matrix (M), and hemagglutinin (HA) genes of the two EIV subtypes. None of the eight assays cross-reacted with any of the other known equine respiratory viruses. Three rRT-PCR assays (EqFlu NP, M, and HA3) which can detect strains of the H3N8 subtype were evaluated using nasal swabs received for routine diagnosis and swabs collected from experimentally inoculated horses. All three rRT-PCR assays have greater specificity and sensitivity than virus isolation by egg inoculation (93%, 89%, and 87% sensitivity for EqFlu NP, EqFlu M, and EqFlu HA3 assays, respectively). These assays had analytical sensitivities of >or=10 EIV RNA molecules. Comparison of the sensitivities of rRT-PCR assays targeting the NP and M genes of both subtypes with egg inoculation and the Directigen Flu A test clearly shows that molecular assays provide the highest sensitivity. The EqFlu HA7 assay targeting the H7 HA gene is highly specific for the H7N7 subtype of EIV. It should enable highly reliable surveillance for the H7N7 subtype, which is thought to be extinct or possibly still circulating at a very low level in nature. The assays that we developed provide a fast and reliable means of EIV diagnosis and subtype identification of EIV subtypes.

  3. Evaluation of the Vitek MS Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry System for Identification of Clinically Relevant Filamentous Fungi

    PubMed Central

    McMullen, Allison R.; Wallace, Meghan A.; Pincus, David H.; Wilkey, Kathy

    2016-01-01

    Invasive fungal infections have a high rate of morbidity and mortality, and accurate identification is necessary to guide appropriate antifungal therapy. With the increasing incidence of invasive disease attributed to filamentous fungi, rapid and accurate species-level identification of these pathogens is necessary. Traditional methods for identification of filamentous fungi can be slow and may lack resolution. Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) has emerged as a rapid and accurate method for identification of bacteria and yeasts, but a paucity of data exists on the performance characteristics of this method for identification of filamentous fungi. The objective of our study was to evaluate the accuracy of the Vitek MS for mold identification. A total of 319 mold isolates representing 43 genera recovered from clinical specimens were evaluated. Of these isolates, 213 (66.8%) were correctly identified using the Vitek MS Knowledge Base, version 3.0 database. When a modified SARAMIS (Spectral Archive and Microbial Identification System) database was used to augment the version 3.0 Knowledge Base, 245 (76.8%) isolates were correctly identified. Unidentified isolates were subcultured for repeat testing; 71/319 (22.3%) remained unidentified. Of the unidentified isolates, 69 were not in the database. Only 3 (0.9%) isolates were misidentified by MALDI-TOF MS (including Aspergillus amoenus [n = 2] and Aspergillus calidoustus [n = 1]) although 10 (3.1%) of the original phenotypic identifications were not correct. In addition, this methodology was able to accurately identify 133/144 (93.6%) Aspergillus sp. isolates to the species level. MALDI-TOF MS has the potential to expedite mold identification, and misidentifications are rare. PMID:27225405

  4. Regulating drug release behavior and kinetics from matrix tablets based on fine particle-sized ethyl cellulose ether derivatives: an in vitro and in vivo evaluation.

    PubMed

    Shah, Kifayat Ullah; Khan, Gul Majid

    2012-01-01

    The design and fabrication of sustained/controlled release dosage forms, employing new excipients capable of extending/controlling the release of drugs from the dosage forms over prolonged periods, has worked well in achieving optimally enhanced therapeutic levels of the drugs. In this sense, the objective of this study was to investigate the suitability of selected cellulose ether derivatives for use in direct compression (DC) and as efficient drug release controlling agents. Controlled release matrix tablets of ciprofloxacin were prepared at different drug-to-polymer (D : P) ratios by direct compression using a fine particle sized ethylcellulose ether derivative (ETHOCEL Standard Premium 7FP) as rate controlling polymer. The tablets obtained were evaluated for various physico-chemical characteristics and in-vitro drug release studies were conducted in phosphate buffer (pH 7.4) using PharmaTest dissolution apparatus at constant temperature of 37 °C ± 0.1. Similarity factor f(2) was employed to the release profiles of test formulations and were compared with marketed ciprofloxacin conventional tablets. Drug release mechanism and the kinetics involved were investigated by fitting the release profile data to various kinetic models. It was found that with increasing the proportion of ethylcellulose ether derivative in the matrix, the drug release was significantly extended up to 24 hours. The tablets exhibited zero order or nearly zero order drug transport mechanism. In vivo drug release performance of the developed controlled release tablets and reference conventional tablets containing ciprofloxacin were determined in rabbit serum according to randomized two-way crossover study design using High Performance Liquid Chromatography. Several bioavailability parameters of both the test tablets and conventional tablets including C(max⁡), T(max⁡) and AUC(0-t) were compared which showed an optimized C(max⁡) and T(max⁡) (P < 0.05). A good correlation was obtained

  5. Machining as a mechanical property test revisited

    NASA Astrophysics Data System (ADS)

    Smith, David L.

    There is much need for data on mechanical behavior of metals at high strains and strain rates. This need is dictated by modeling of processes like forming and machining, wherein the material in the deformation zone is subjected to severe deformation conditions atypical of conventional material property tests such as tension and torsion. Accurate flow stress data is an essential input for robust prediction of process outputs. Similar requirements arise from applications in high speed ballistic penetration and design of materials for armor. Since the deformation zone in cutting of metals is characterized by unique and extreme combinations of strain, strain rate and temperature, an opportunity exists for using plane-strain cutting as a mechanical property test for measuring flow properties of metals. The feasibility of using plane-strain cutting to measure flow properties of metals is revisited in the light of recent data showing controllability of the deformation conditions in chip formation by systematic variation of process input parameters. A method is outlined as to how the deformation conditions can be varied by changing the process parameters. The method is applied to cutting of commercially pure copper (FCC), iron (BCC) and zinc (HCP). Forces and chip geometries are measured, in conjunction with particle image velocimetry characterization of the deformation using high speed image sequences. The flow stresses are estimated from these measurements. The measured flow stress and its dependence on strain are shown to agree well with prior measurements of these parameters using conventional tests, and flow stress inferred from hardness characterization. The method is also demonstrated to be able to measure properties of metals that recrystallize at room temperature (zinc), wherein quasi-static tests predict much lower strength. Sources of variability and uncertainty in the application of this measurement technique are discussed. Future work in the context of further

  6. Gravity current jump conditions, revisited

    NASA Astrophysics Data System (ADS)

    Ungarish, Marius; Hogg, Andrew J.

    2016-11-01

    Consider the flow of a high-Reynolds-number gravity current of density ρc in an ambient fluid of density ρa in a horizontal channel z ∈ [ 0 , H ] , with gravity in - z direction. The motion is often modeled by a two-layer formulation which displays jumps (shocks) in the height of the interface, in particular at the leading front of the dense layer. Various theoretical models have been advanced to predict the dimensionless speed of the jump, Fr = U /√{g' h } ; g' , h are reduced gravity and jump height. We revisit this problem and using the Navier-Stokes equations, integrated over a control volume embedding the jump, derive balances of mass and momentum fluxes. We focus on understanding the closures needed to complete this model and we show the vital need to understand the pressure head losses over the jump, which we show can be related to the vorticity fluxes at the boundaries of the control volume. Our formulation leads to two governing equations for three dimensionless quantities. Closure requires one further assumption, depending on which we demonstrate that previous models for gravity current fronts and internal bores can be recovered. This analysis yield new insights into existing results, and also provides constraints for potential new formulae.

  7. Revisiting intracellular calcium signaling semantics.

    PubMed

    Haiech, Jacques; Audran, Emilie; Fève, Marie; Ranjeva, Raoul; Kilhoffer, Marie-Claude

    2011-12-01

    Cells use intracellular free calcium concentration changes for signaling. Signal encoding occurs through both spatial and temporal modulation of the free calcium concentration. The encoded message is detected by an ensemble of intracellular sensors forming the family of calcium-binding proteins (CaBPs) which must faithfully translate the message using a new syntax that is recognized by the cell. The cell is home to a significant although limited number of genes coding for proteins involved in the signal encoding and decoding processes. In a cell, only a subset of this ensemble of genes is expressed, leading to a genetic regulation of the calcium signal pathways. Calmodulin (CaM), the most ubiquitous expressed intracellular calcium-binding protein, plays a major role in calcium signal translation. Similar to a hub, it is central to a large and finely tuned network, receiving information, integrating it and dispatching the cognate response. In this review, we examine the different steps starting with an external stimulus up to a cellular response, with special emphasis on CaM and the mechanism by which it decodes calcium signals and translates it into exquisitely coordinated cellular events. By this means, we will revisit the calcium signaling semantics, hoping that we will ease communication between scientists dealing with calcium signals in different biological systems and different domains.

  8. Revisiting Bohr's semiclassical quantum theory.

    PubMed

    Ben-Amotz, Dor

    2006-10-12

    Bohr's atomic theory is widely viewed as remarkable, both for its accuracy in predicting the observed optical transitions of one-electron atoms and for its failure to fully correspond with current electronic structure theory. What is not generally appreciated is that Bohr's original semiclassical conception differed significantly from the Bohr-Sommerfeld theory and offers an alternative semiclassical approximation scheme with remarkable attributes. More specifically, Bohr's original method did not impose action quantization constraints but rather obtained these as predictions by simply matching photon and classical orbital frequencies. In other words, the hydrogen atom was treated entirely classically and orbital quantized emerged directly from the Planck-Einstein photon quantization condition, E = h nu. Here, we revisit this early history of quantum theory and demonstrate the application of Bohr's original strategy to the three quintessential quantum systems: an electron in a box, an electron in a ring, and a dipolar harmonic oscillator. The usual energy-level spectra, and optical selection rules, emerge by solving an algebraic (quadratic) equation, rather than a Bohr-Sommerfeld integral (or Schroedinger) equation. However, the new predictions include a frozen (zero-kinetic-energy) state which in some (but not all) cases lies below the usual zero-point energy. In addition to raising provocative questions concerning the origin of quantum-chemical phenomena, the results may prove to be of pedagogical value in introducing students to quantum mechanics.

  9. Preparation of SiC based Aluminium metal matrix nano composites by high intensity ultrasonic cavitation process and evaluation of mechanical and tribological properties

    NASA Astrophysics Data System (ADS)

    Murthy, N. V.; Prasad Reddy, A.; Selvaraj, N.; Rao, C. S. P.

    2016-09-01

    Request augments on a worldwide scale for the new materials. The metal matrix nano composites can be used in numerous applications of helicopter structural parts, gas turbine exit guide vane's, space shuttle, and other structural applications. The key mailman to ameliorate performance of composite matrix in aluminium alloy metal reinforces nano particles in the matrix of alloy uniformly, which ameliorates composite properties without affecting limit of ductility. The ultrasonic assisted stir casting helped agitation was successfully used to fabricate Al 2219 metal matrix of alloy reinforced with (0.5, 1, 1.5 and 2) wt.% of nano silicon carbide (SiC) particles of different sizes 50nm and 150nm. The micrographs of scanning electron microscopy of nano composite were investigated it reveals that the uniform dispersion of nano particles silicon carbide in aluminium alloy 2219 matrix and with the low porosity. How the specific wear rate was vary with increasing weight percentage of nano particles at constant load and speed as shown in results and discussions. And the mechanical properties showed that the ultimate tensile strength and hardness of metal matrix nano composite AA 2219 / nano SiC of 50nm and 150nm lean to augment with increase weight percentage of silicon carbide content in the matrix alloy.

  10. Revisit boundary conditions for the self-adjoint angular flux formulation

    SciTech Connect

    Wang, Yaqi; Gleicher, Frederick N.

    2015-03-01

    We revisit the boundary conditions for SAAF. We derived the equivalent parity variational form ready for coding up. The more rigorous approach of evaluating odd parity should be solving the odd parity equation coupled with the even parity. We proposed a symmetric reflecting boundary condition although neither positive definiteness nor even-odd decoupling is achieved. A simple numerical test verifies the validity of these boundary conditions.

  11. The Future of Engineering Education--Revisited

    ERIC Educational Resources Information Center

    Wankat, Phillip C.; Bullard, Lisa G.

    2016-01-01

    This paper revisits the landmark CEE series, "The Future of Engineering Education," published in 2000 (available free in the CEE archives on the internet) to examine the predictions made in the original paper as well as the tools and approaches documented. Most of the advice offered in the original series remains current. Despite new…

  12. Phenomenology of n - n ¯ oscillations revisited

    DOE PAGES

    Gardner, S.; Jafari, E.

    2015-05-22

    We revisit the phenomenology of n-n¯ oscillations in the presence of external magnetic fields, highlighting the role of spin. We show, contrary to long-held belief, that the n-n¯ transition rate need not be suppressed, opening new opportunities for its empirical study.

  13. Revisiting separation properties of convex fuzzy sets

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Separation of convex sets by hyperplanes has been extensively studied on crisp sets. In a seminal paper separability and convexity are investigated, however there is a flaw on the definition of degree of separation. We revisited separation on convex fuzzy sets that have level-wise (crisp) disjointne...

  14. The Rotating Morse-Pekeris Oscillator Revisited

    ERIC Educational Resources Information Center

    Zuniga, Jose; Bastida, Adolfo; Requena, Alberto

    2008-01-01

    The Morse-Pekeris oscillator model for the calculation of the vibration-rotation energy levels of diatomic molecules is revisited. This model is based on the realization of a second-order exponential expansion of the centrifugal term about the minimum of the vibrational Morse oscillator and the subsequent analytical resolution of the resulting…

  15. Topological string theory revisited I: The stage

    NASA Astrophysics Data System (ADS)

    Jia, Bei

    2016-08-01

    In this paper, we reformulate topological string theory using supermanifolds and supermoduli spaces, following the approach worked out by Witten (Superstring perturbation theory revisited, arXiv:1209.5461). We intend to make the construction geometrical in nature, by using supergeometry techniques extensively. The goal is to establish the foundation of studying topological string amplitudes in terms of integration over appropriate supermoduli spaces.

  16. Revisiting the Regenerative Possibilities of Ortiz

    ERIC Educational Resources Information Center

    Duques, Matthew

    2004-01-01

    The author of this article revisits Simon Ortiz's poem, "From Sand Creek," in which the latter can in so few words convey both the horrific tragedy of conquest and colonization, while at the same time find a space for possibility, a means for recovery that is never about forgetting but always occurs as a kind of recuperative remembering. Ortiz…

  17. Revisiting Basic Counseling Skills with Children

    ERIC Educational Resources Information Center

    Van Velsor, Patricia

    2004-01-01

    Counseling with children can be challenging for counselors whose training focused on adult clients. The purpose of this article is to offer information to counselors seeking to improve their skills with children, revisiting a topic discussed in an earlier Journal of Counseling & Development article by P. Erdman and R. Lampe (1996). Examples of…

  18. The black hole S-Matrix from quantum mechanics

    NASA Astrophysics Data System (ADS)

    Betzios, Panagiotis; Gaddam, Nava; Papadoulaki, Olga

    2016-11-01

    We revisit the old black hole S-Matrix construction and its new partial wave expansion of 't Hooft. Inspired by old ideas from non-critical string theory & c = 1 Matrix Quantum Mechanics, we reformulate the scattering in terms of a quantum mechanical model — of waves scattering off inverted harmonic oscillator potentials — that exactly reproduces the unitary black hole S-Matrix for all spherical harmonics; each partial wave corresponds to an inverted harmonic oscillator with ground state energy that is shifted relative to the s-wave oscillator. Identifying a connection to 2d string theory allows us to show that there is an exponential degeneracy in how a given total initial energy may be distributed among many partial waves of the 4d black hole.

  19. Multicenter Evaluation of the Vitek MS Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry System for Identification of Gram-Positive Aerobic Bacteria

    PubMed Central

    Burnham, Carey-Ann D.; Bythrow, Maureen; Garner, Omai B.; Ginocchio, Christine C.; Jennemann, Rebecca; Lewinski, Michael A.; Manji, Ryhana; Mochon, A. Brian; Procop, Gary W.; Richter, Sandra S.; Sercia, Linda; Westblade, Lars F.; Ferraro, Mary Jane; Branda, John A.

    2013-01-01

    Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF) is gaining momentum as a tool for bacterial identification in the clinical microbiology laboratory. Compared with conventional methods, this technology can more readily and conveniently identify a wide range of organisms. Here, we report the findings from a multicenter study to evaluate the Vitek MS v2.0 system (bioMérieux, Inc.) for the identification of aerobic Gram-positive bacteria. A total of 1,146 unique isolates, representing 13 genera and 42 species, were analyzed, and results were compared to those obtained by nucleic acid sequence-based identification as the reference method. For 1,063 of 1,146 isolates (92.8%), the Vitek MS provided a single identification that was accurate to the species level. For an additional 31 isolates (2.7%), multiple possible identifications were provided, all correct at the genus level. Mixed-genus or single-choice incorrect identifications were provided for 18 isolates (1.6%). Although no identification was obtained for 33 isolates (2.9%), there was no specific bacterial species for which the Vitek MS consistently failed to provide identification. In a subset of 463 isolates representing commonly encountered important pathogens, 95% were accurately identified to the species level and there were no misidentifications. Also, in all but one instance, the Vitek MS correctly differentiated Streptococcus pneumoniae from other viridans group streptococci. The findings demonstrate that the Vitek MS system is highly accurate for the identification of Gram-positive aerobic bacteria in the clinical laboratory setting. PMID:23658261

  20. Investigation and Evaluation of an in Situ Interpolymer Complex of Carbopol with Polyvinylpyrrolidone as a Matrix for Gastroretentive Tablets of Ranitidine Hydrochloride.

    PubMed

    Yusif, Rehab Mohammad; Abu Hashim, Irhan Ibrahim; Mohamed, Elham Abdelmonem; El Rakhawy, Mohamed Magdy

    2016-01-01

    Carbopol (CP) is a biocompatible bioadhesive polymer used as a matrix for gastroretentive (GR) tablets, however, its rapid hydration shortens its bioadhesion and floating when incorporated in effervescent formulae. The interpolymer complexation of CP with polyvinylpyrrolidone (PVP) significantly reduced the excessive hydration of CP, prolonging floating and maintaining the mucoadhesiveness. In early attempts, a lengthy process was followed to prepare such an interpolymer complex. In this study, an in situ interpolymer complexation between CP and two grades of PVP (K25 and K90) in 0.1 N HCl was investigated and characterized by Fourier transform infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC). Hence, directly compressed GR tablets of different combinations of PVP and CP with sodium bicarbonate (SB) as an effervescent agent were examined for prolonged gastroretention and sustained release of ranitidine hydrochloride (RHCl) as a model drug. Tablets were evaluated for in vitro buoyancy, bioadhesiveness, swelling, and drug release in 0.1 N HCl. All GR tablets containing PVP-CP combinations achieved more prolonged floating (>24 h) than CP tablets (5.2 h). Their bioadhesiveness, swelling, and drug release were dependent on the PVP molecular weight and its ratio to CP. Drug release profiles of all formulae followed non-Fickian diffusion. Formula containing the PVP K90-CP combination at a respective ratio of 1 : 3 (P90C13) was a promising system, exhibiting good floating and bioadhesive properties as well as sustained drug release. Abdominal X-ray imaging of P90C13 formula, loaded with barium sulfate, in six healthy volunteers showed a mean gastric retention period of 6.8±0.3 h.

  1. Evaluation of matrix-assisted laser desorption ionization-time of flight mass spectrometry for species identification of Acinetobacter strains isolated from blood cultures.

    PubMed

    Kishii, K; Kikuchi, K; Matsuda, N; Yoshida, A; Okuzumi, K; Uetera, Y; Yasuhara, H; Moriya, K

    2014-05-01

    The clinical relevance of Acinetobacter species, other than A. baumannii, as human pathogens has not been sufficiently assessed owing to the insufficiency of simple phenotypic clinical diagnostic laboratory tests. Infections caused by these organisms have different impacts on clinical outcome and require different treatment and management approaches. It is therefore important to correctly identify Acinetobacter species. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has been introduced to identify a wide range of microorganisms in clinical laboratories, but only a few studies have examined its utility for identifying Acinetobacter species, particularly those of the non-Acinetobacter baumannii complex. We therefore evaluated MALDI-TOF MS for identification of Acinetobacter species by comparing it with sequence analysis of rpoB using 123 isolates of Acinetobacter species from blood. Of the isolates examined, we identified 106/123 (86.2%) to species, and 16/123 (13.0%) could only be identified as acinetobacters. The identity of one isolate could not be established. Of the 106 species identified, 89/106 (84.0%) were confirmed by rpoB sequence analysis, and 17/106 (16.0%) were discordant. These data indicate correct identification of 89/123 (72.4%) isolates. Surprisingly, all blood culture isolates were identified as 13 species of Acinetobacter, and the incidence of Acinetobacter pittii was unexpectedly high (42/123; 34.1%) and exceeded that of A. baumannii (22/123; 17.9%). Although the present identification rate using MALDI-TOF MS is not acceptable for species-level identification of Acinetobacter, further expansion of the database should remedy this situation.

  2. Multicenter evaluation of the Vitek MS matrix-assisted laser desorption ionization-time of flight mass spectrometry system for identification of Gram-positive aerobic bacteria.

    PubMed

    Rychert, Jenna; Burnham, Carey-Ann D; Bythrow, Maureen; Garner, Omai B; Ginocchio, Christine C; Jennemann, Rebecca; Lewinski, Michael A; Manji, Ryhana; Mochon, A Brian; Procop, Gary W; Richter, Sandra S; Sercia, Linda; Westblade, Lars F; Ferraro, Mary Jane; Branda, John A

    2013-07-01

    Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF) is gaining momentum as a tool for bacterial identification in the clinical microbiology laboratory. Compared with conventional methods, this technology can more readily and conveniently identify a wide range of organisms. Here, we report the findings from a multicenter study to evaluate the Vitek MS v2.0 system (bioMérieux, Inc.) for the identification of aerobic Gram-positive bacteria. A total of 1,146 unique isolates, representing 13 genera and 42 species, were analyzed, and results were compared to those obtained by nucleic acid sequence-based identification as the reference method. For 1,063 of 1,146 isolates (92.8%), the Vitek MS provided a single identification that was accurate to the species level. For an additional 31 isolates (2.7%), multiple possible identifications were provided, all correct at the genus level. Mixed-genus or single-choice incorrect identifications were provided for 18 isolates (1.6%). Although no identification was obtained for 33 isolates (2.9%), there was no specific bacterial species for which the Vitek MS consistently failed to provide identification. In a subset of 463 isolates representing commonly encountered important pathogens, 95% were accurately identified to the species level and there were no misidentifications. Also, in all but one instance, the Vitek MS correctly differentiated Streptococcus pneumoniae from other viridans group streptococci. The findings demonstrate that the Vitek MS system is highly accurate for the identification of Gram-positive aerobic bacteria in the clinical laboratory setting.

  3. Five years on: Revisiting GSN data quality

    NASA Astrophysics Data System (ADS)

    Gee, L. S.; Nettles, M.; Ekstrom, G.; Davis, J. P.; Ringler, A. T.; Storm, T. L.; Wilson, D.; Anderson, K. R.

    2014-12-01

    In 2010, the Lamont Waveform Quality Center (WQC) conducted an in-depth review of ten stations in the Global Seismographic Network (GSN). IU stations (CASY, DAV, KIP, KONO, WCI), IC stations (SSE, XAN), and II stations (ALE, DGAR, RPN) were analyzed using a scaling analysis based on data-synthetic comparisons, evaluation of noise levels, assessment of inter-sensor coherence, and polarization analysis. These reports (available from http://www.ldeo.columbia.edu/~ekstrom/Projects/WQC.html) highlighted a number of significant problems in GSN data quality, including the frequency-dependent loss of gain in the STS-1 seismometer (Ekström et al., 2006) that has been attributed to the presence of humidity in the electronics, cables, and connectors (Yuki and Ishihara, 2002; Hutt and Ringler, 2011). The reports from the WQC spurred a number of changes in the operation of the GSN, including the adoption of the policy of annual calibrations and the development of new tools and metrics to monitor, evaluate, and communicate data quality. In parallel, the USGS' Albuquerque Seismological Laboratory (ASL) and UCSD's Project IDA worked with the IRIS Consortium to upgrade GSN stations with new data acquisition systems, to refurbish the STS-1 seismometers with new electronics, and to expand the deployment of secondary broadband sensors. We revisit the 2010 reports, using the tools of the WQC as well as a number of newly developed tools such as the USGS' Data Quality Analyzer and IRIS' MUSTANG, and provide an update on GSN data quality. Our initial focus is on CASY and KIP, the first two stations reviewed by the WQC. Our goal is to evaluate progress in the last five years and assess our ability to quantify data quality as well as to identify potential problems that could compromise data quality in the future. Ekström, G., C. A. Dalton, and M. Nettles (2006). Observations of time-dependent errors in long-period instrument gain at global seismic stations. Seismological Research Letters

  4. Revisiting the 1761 Transatlantic Tsunami

    NASA Astrophysics Data System (ADS)

    Baptista, Maria Ana; Wronna, Martin; Miranda, Jorge Miguel

    2016-04-01

    The tsunami catalogs of the Atlantic include two transatlantic tsunamis in the 18th century the well known 1st November 1755 and the 31st March 1761. The 31st March 1761 earthquake struck Portugal, Spain, and Morocco. The earthquake occurred around noontime in Lisbon alarming the inhabitants and throwing down ruins of the past 1st November 1755 earthquake. According to several sources, the earthquake was followed by a tsunami observed as far as Cornwall (United Kingdom), Cork (Ireland) and Barbados (Caribbean). The analysis of macroseismic information and its compatibility with tsunami travel time information led to a source area close to the Ampere Seamount with an estimated epicenter circa 34.5°N 13°W. The estimated magnitude of the earthquake was 8.5. In this study, we revisit the tsunami observations, and we include a report from Cadiz not used before. We use the results of the compilation of the multi-beam bathymetric data, that covers the area between 34°N - 38°N and 12.5°W - 5.5°W and use the recent tectonic map published for the Southwest Iberian Margin to select among possible source scenarios. Finally, we use a non-linear shallow water model that includes the discretization and explicit leap-frog finite difference scheme to solve the shallow water equations in the spherical or Cartesian coordinate to compute tsunami waveforms and tsunami inundation and check the results against the historical descriptions to infer the source of the event. This study received funding from project ASTARTE- Assessment Strategy and Risk Reduction for Tsunamis in Europe a collaborative project Grant 603839, FP7-ENV2013 6.4-3

  5. Evaluation and prevention of the negative matrix effect of terpenoids on pesticides in apples quantification by gas chromatography-tandem mass spectrometry.

    PubMed

    Giacinti, Géraldine; Raynaud, Christine; Capblancq, Sophie; Simon, Valérie

    2017-02-03

    The sample matrix can enhance the gas chromatography signal of pesticide residues relative to that obtained with the same concentration of pesticide in solvent. This paper is related to negative matrix effects observed in coupled gas chromatography-mass spectrometry ion trap (GC/MS(2)) quantification of pesticides in concentrated extracts of apple peel prepared by the Quick Easy Cheap Effective Rugged and Safe (QuEChERS) method. It is focused on the pesticides most frequently used on the apple varieties studied, throughout the crop cycle, right up to harvest, to combat pests and diseases and to improve fruit storage properties. Extracts from the fleshy receptacle (flesh), the epiderm (peel) and fruit of three apple varieties were studied by high-performance thin-layer chromatography hyphenated with UV-vis light detection (HPTLC/UV visible). The peel extracts had high concentrations of triterpenic acids (oleanolic and ursolic acids), reaching 25mgkg(-1), whereas these compounds were not detected in the flesh extracts (<0.05mgkg(-1)). A significant relationship has been found between the levels of these molecules and negative matrix effects in GC/MS(2). The differences in the behavior of pesticides with respect to matrix effects can be accounted for by the physicochemical characteristics of the molecules (lone pairs, labile hydrogen, conjugation). The HPTLC/UV visible method developed here for the characterization of QuEChERS extracts acts as a complementary clean-up method, aimed to decrease the negative matrix effects of such extracts.

  6. Evaluation and prevention of the negative matrix effect of terpenoids on pesticides in apples quantification by gas chromatography-tandem mass spectrometry.

    PubMed

    Giacinti, Géraldine; Raynaud, Christine; Capblancq, Sophie; Simon, Valérie

    2016-12-21

    The sample matrix can enhance the gas chromatography signal of pesticide residues relative to that obtained with the same concentration of pesticide in solvent. This paper is related to negative matrix effects observed in coupled gas chromatography-mass spectrometry ion trap (GC/MS(2)) quantification of pesticides in concentrated extracts of apple peel prepared by the Quick Easy Cheap Effective Rugged and Safe (QuEChERS) method. It is focused on the pesticides most frequently used on the apple varieties studied, throughout the crop cycle, right up to harvest, to combat pests and diseases and to improve fruit storage properties. Extracts from the fleshy receptacle (flesh), the epiderm (peel) and fruit of three apple varieties were studied by high-performance thin-layer chromatography hyphenated with UV-vis light detection (HPTLC/UV visible). The peel extracts had high concentrations of triterpenic acids (oleanolic and ursolic acids), reaching 25mgkg(-1), whereas these compounds were not detected in the flesh extracts (<0.05mgkg(-1)). A significant relationship has been found between the levels of these molecules and negative matrix effects in GC/MS(2). The differences in the behavior of pesticides with respect to matrix effects can be accounted for by the physicochemical characteristics of the molecules (lone pairs, labile hydrogen, conjugation). The HPTLC/UV visible method developed here for the characterization of QuEChERS extracts acts as a complementary clean-up method, aimed to decrease the negative matrix effects of such extracts.

  7. Associations between in-hospital bed occupancy and unplanned 72-h revisits to the emergency department: a register study

    PubMed Central

    2014-01-01

    Background A possible downstream effect of high in-hospital bed occupancy is that patients in the emergency department (ED) who would benefit from in-hospital care are denied admission. The present study aimed at evaluating this hypothesis through investigating associations between in-hospital bed occupancy at the time of presentation in the ED and the probability for unplanned 72-hour (72-h) revisits to the ED among patients discharged at index. A second outcome was unplanned 72-h revisits resulting in admission. Methods All visits to the ED of a 420-bed emergency hospital in southern Sweden between 1 January 2011 and 31 December 2012, which did not result in admission, death, or transfer to another hospital were included. Revisiting fractions were computed for in-hospital occupancy intervals <85%, 85% to 90%, 90% to 95%, 95% to 100%, 100% to 105%, and ≥105%. Multivariate models were constructed in an attempt to take confounding factors from, e.g., presenting complaints, age, referral status, and triage priority into account. Results Included in the study are 81,878 visits. The fraction of unplanned 72-h revisits/unplanned 72-h revisits resulting in admission was 5.8%/1.4% overall, 6.2%/1.4% for occupancy <85%, 6.4%/1.5% for occupancy 85% to 90%, 5.8%/1.4% for occupancy 90% to 95%, 6.0%/1.6% for occupancy 95% to 100%, 5.4%/1.6% for occupancy 100% to 105%, and 4.9%/1.4% for occupancy ≥105%. In the multivariate models, a trend to lower probability of unplanned 72-h revisits was observed at occupancy ≥105% compared to occupancy <95% (OR 0.88, CI 0.76 to 1.01). No significant associations between in-hospital occupancy at index and the probability of making unplanned 72-h revisits resulting in admission were observed. Conclusions The lack of associations between in-hospital occupancy and unplanned 72-h revisits does not support the hypothesis that ED patients are inappropriately discharged when in-hospital beds are scarce. The results are reassuring as they

  8. Hybrid matrix fiber composites

    DOEpatents

    Deteresa, Steven J.; Lyon, Richard E.; Groves, Scott E.

    2003-07-15

    Hybrid matrix fiber composites having enhanced compressive performance as well as enhanced stiffness, toughness and durability suitable for compression-critical applications. The methods for producing the fiber composites using matrix hybridization. The hybrid matrix fiber composites include two chemically or physically bonded matrix materials, whereas the first matrix materials are used to impregnate multi-filament fibers formed into ribbons and the second matrix material is placed around and between the fiber ribbons that are impregnated with the first matrix material and both matrix materials are cured and solidified.

  9. Using the Boston Consulting Group Matrix To Analyze College Programs: Should that New Major Be Approved?

    ERIC Educational Resources Information Center

    Green, Mark T.; Odom, Lamar; Alexander, Jacquelyn; Hudspeth, Elizabeth; Hudsepth, Gregory

    2003-01-01

    Describes potential use of Boston Consulting Group Matrix to evaluate proposed new college and university programs or majors. The product evaluation matrix consisted of two major variables: product growth rate and market share. Provides an example of the matrix. (PKP)

  10. Development and Evaluation of an Externally Air-Cooled Low-Flow torch and the Attenuation of Space Charge and Matrix Effects in Inductively Coupled Plasma Mass Spectrometry

    SciTech Connect

    Praphairaksit, Narong

    2000-09-12

    An externally air-cooled low-flow torch has been constructed and successfully demonstrated for applications in inductively coupled plasma mass spectrometry (ICP-MS). The torch is cooled by pressurized air flowing at ~70 L/min through a quartz air jacket onto the exterior of the outer tube. The outer gas flow rate and operating RF forward power are reduced considerably. Although plasmas can be sustained at the operating power as low as 400 W with a 2 L/min of outer gas flow, somewhat higher power and outer gas flows are advisable. A stable and analytical useful plasma can be obtained at 850 W with an outer gas flow rate of ~4 L/min. Under these conditions, the air-cooled plasma produces comparable sensitivities, doubly charged ion ratios, matrix effects and other analytical merits as those produced by a conventional torch while using significantly less argon and power requirements. Metal oxide ion ratios are slightly higher with the air-cooled plasma but can be mitigated by reducing the aerosol gas flow rate slightly with only minor sacrifice in analyte sensitivity. A methodology to alleviate the space charge and matrix effects in ICP-MS has been developed. A supplemental electron source adapted from a conventional electron impact ionizer is added to the base of the skimmer. Electrons supplied from this source downstream of the skimmer with suitable amount and energy can neutralize the positive ions in the beam extracted from the plasma and diminish the space charge repulsion between them. As a result, the overall ion transmission efficiency and consequent analyte ion sensitivities are significantly improved while other important analytical aspects, such as metal oxide ion ratio, doubly charged ion ratio and background ions remain relatively unchanged with the operation of this electron source. This technique not only improves the ion transmission efficiency but also minimizes the matrix effects drastically. The matrix-induced suppression of signal for even the most

  11. The flow along an external corner revisited

    NASA Astrophysics Data System (ADS)

    Denier, Jim; Jewell, Nathaniel

    2013-11-01

    We revisit the problem of the flow of an almost inviscid fluid along an external corner made from the junction of two quarter infinite plates joined at an angle 0 < α < π / 2 . The structure of the boundary layer which develops along the corner is explored using a computational approach based upon a spectral element discretisation of the steady two-dimensional boundary-layer equations. We pay particular attention to the case when the angle α is small, thus approximating the semi-infinte quarter plate problem considered by Stewartson (1961) and recently revisited by Duck & Hewitt (2012). Our results, which demonstrate a thickening of the boundary-layer near the sharp corner, will be discussed in the context of the asymptotic theory developed in the aforementioned papers.

  12. Development and evaluation of natural gum-based extended release matrix tablets of two model drugs of different water solubilities by direct compression.

    PubMed

    Ofori-Kwakye, Kwabena; Mfoafo, Kwadwo Amanor; Kipo, Samuel Lugrie; Kuntworbe, Noble; Boakye-Gyasi, Mariam El

    2016-01-01

    The study was aimed at developing extended release matrix tablets of poorly water-soluble diclofenac sodium and highly water-soluble metformin hydrochloride by direct compression using cashew gum, xanthan gum and hydroxypropylmethylcellulose (HPMC) as release retardants. The suitability of light grade cashew gum as a direct compression excipient was studied using the SeDeM Diagram Expert System. Thirteen tablet formulations of diclofenac sodium (∼100 mg) and metformin hydrochloride (∼200 mg) were prepared with varying amounts of cashew gum, xanthan gum and HPMC by direct compression. The flow properties of blended powders and the uniformity of weight, crushing strength, friability, swelling index and drug content of compressed tablets were determined. In vitro drug release studies of the matrix tablets were conducted in phosphate buffer (diclofenac: pH 7.4; metformin: pH 6.8) and the kinetics of drug release was determined by fitting the release data to five kinetic models. Cashew gum was found to be suitable for direct compression, having a good compressibility index (ICG) value of 5.173. The diclofenac and metformin matrix tablets produced generally possessed fairly good physical properties. Tablet swelling and drug release in aqueous medium were dependent on the type and amount of release retarding polymer and the solubility of drug used. Extended release of diclofenac (∼24 h) and metformin (∼8-12 h) from the matrix tablets in aqueous medium was achieved using various blends of the polymers. Drug release from diclofenac tablets fitted zero order, first order or Higuchi model while release from metformin tablets followed Higuchi or Hixson-Crowell model. The mechanism of release of the two drugs was mostly through Fickian diffusion and anomalous non-Fickian diffusion. The study has demonstrated the potential of blended hydrophilic polymers in the design and optimization of extended release matrix tablets for soluble and poorly soluble drugs by direct

  13. Revisiting Cementoblastoma with a Rare Case Presentation

    PubMed Central

    Narasimhan, Malathi; Ramalingam, Suganya; Anandan, Soumya; Ranganathan, Subhashini

    2017-01-01

    Cementoblastoma is a rare benign odontogenic neoplasm which is characterized by the proliferation of cellular cementum. Diagnosis of cementoblastoma is challenging because of its protracted clinical, radiographic features, and bland histological appearance; most often cementoblastoma is often confused with other cementum and bone originated lesions. The aim of this article is to overview/revisit, approach the diagnosis of cementoblastoma, and also present a unique radiographic appearance of a cementoblastoma lesion associated with an impacted tooth. PMID:28337352

  14. [Comparative evaluation of physical-mechanical properties and surface morphology of the samples of base self cured acrylic resin "Redont-kolir" polymerized in the silicone and alginate matrixes].

    PubMed

    2014-01-01

    Determination of advantages of using silicone or alginate impression material as a matrix is decisive for quality of immediate and transitional dentures manufactured by the direct method using self-cured acrylic resins. The aim of this study was a comparative evaluation of physical-mechanical properties and surface morphology of the samples of base self-cured acrylic resin "Redont-kolir" polymerized in the silicone and alginate matrix. The samples were polymerized in the C-silicone - "Zeta plus-putty" ("Zhermack", Italy) and alginate -"Ypeen" ("Spofa Dental", Czech Republic) matrixes under different regimes: 1) in the pneumopolymerizer "Averon" at an air pressure of 3 atm., a temperature of 450C for 15 minutes, and 2) polymerization in water at 450C for 15 minutes. We determined the following physical and mechanical properties: bending load, toughness, bending stress at break, hardness by Heppler, conical point of fluidity and water absorption. Electron microscopy studies of the samples have been conducted on electronic raster microscope JSM-840 ("Jeol", Japan). As a result of studies, it was found that the optimum regime of polymerization for acrylate "Redont-kolir" is in the pneumopolymerizer "Averon" at an air pressure of 3 atm., a temperature of 450 C for 15 minutes. By the results of studying the surface morphology of the samples we can draw a conclusion that the use of an alginate impression material as matrix allows to obtain a qualitatively better surface of denture. But taking into account the technological properties of the alginate impression materials, namely an expressed shrinkage, their use for this purpose must be limited by the time during which the impression matrix remain stable in size, which is specified by manufacturer's recommendations.

  15. BHQ revisited (2): Texture development

    NASA Astrophysics Data System (ADS)

    Kilian, Rüdiger; Heilbronner, Renée

    2016-04-01

    appears that grains can be unfavourably oriented for glide despite their c-axis direction falling in those positions which were used in the "classical" interpretation. Additionally, it turns out that grain-scale dispersion axes can be used to describe the kinematic behaviour in a more consistent way compared to the rotations axes obtained from intragranular misorientations in the range of 2-10°. The implications derived from the experimental data set will be compared to data obtained from natural quartz mylonites which formed in a comparable recrystallization regime. This is the companion poster to "BHQ revisited (I) looking at grain size" where the development of the dynamically recrystallized grain size is addressed. Reference cited: Heilbronner, R., and J. Tullis (2006), Evolution of c axis pole figures and grain size during dynamic recrystallization: Results from experimentally sheared quartzite, J. Geophys. Res., 111, B10202, doi:10.1029/2005JB004194.

  16. One-step preparation of CdS nanocrystals supported on thiolated silica-gel matrix and evaluation of photocatalytic performance.

    PubMed

    Andrade, George R S; Nascimento, Cristiane C; Neves, Erick C; Barbosa, Cintya D'Angeles Espirito Santo; Costa, Luiz P; Barreto, Ledjane S; Gimenez, Iara F

    2012-02-15

    Here we report the use of a thiol-functionalized silica-gel to prepare supported CdS nanocrystals by a facile one-step procedure. Upon changing the relative proportion of the matrix we obtained nanocrystals with different average sizes and size distributions, as evidenced by spectroscopic measurements as well as TEM images. Photoluminescence spectra also indicated that the main effect of the matrix is related to the size control since the spectral profiles were found to be strongly dependent on the excitation wavelength. The performance of the material in the photocatalytic degradation of two commercial dyes (methylene blue and rhodamine 6G) has been tested under sunlight radiation, showing promising results. Almost complete decolorization has been observed after 80 min of exposure, with no adsorption on the silica surface.

  17. Evaluation of the Bruker Biotyper Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry System for Identification of Blood Isolates of Acinetobacter Species

    PubMed Central

    Hsueh, Po-Ren; Kuo, Lu-Cheng; Chang, Tsung-Chain; Lee, Tai-Fen; Teng, Shih-Hua; Chuang, Yu-Chung; Teng, Lee-Jene

    2014-01-01

    Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) (Bruker Biotyper) was able to accurately identify 98.6% (142/144) of Acinetobacter baumannii isolates, 72.4% (63/87) of A. nosocomialis isolates, and 97.6% (41/42) of A. pittii isolates. All Acinetobacter junii, A. ursingii, A. johnsonii, and A. radioresistens isolates (n = 28) could also be identified correctly by Bruker Biotyper. PMID:24899038

  18. Multiresidue analysis of multiclass pesticides and polyaromatic hydrocarbons in fatty fish by gas chromatography tandem mass spectrometry and evaluation of matrix effect.

    PubMed

    Chatterjee, Niladri S; Utture, Sagar; Banerjee, Kaushik; Ahammed Shabeer, T P; Kamble, Narayan; Mathew, Suseela; Ashok Kumar, K

    2016-04-01

    This paper reports a selective and sensitive method for multiresidue determination of 119 chemical residues including pesticides and polyaromatic hydrocarbons (PAH) in high fatty fish matrix. The novel sample preparation method involved extraction of the target analytes from homogenized fish meat (5 g) in acetonitrile (15 mL, 1% acetic acid) after three-phase partitioning with hexane (2 mL) and the remaining aqueous layer. An aliquot (1.5 mL) of the acetonitrile layer was aspirated and subjected to two-stage dispersive solid phase extraction (dSPE) cleanup and the residues were finally estimated by gas chromatography mass spectrometry with selected reaction monitoring (GC-MS/MS). The co-eluted matrix components were identified on the basis of their accurate mass by GC with quadrupole time of flight MS. Addition of hexane during extraction and optimized dSPE cleanup significantly minimized the matrix effects. Recoveries at 10, 25 and 50 μg/kg were within 60-120% with associated precision, RSD<11%.

  19. Confirmation of β-agonist residues in bovine retina and liver using HPLC-MS/MS and evaluation of matrix-dependent problems.

    PubMed

    Regal, Patricia; Díaz-Bao, Mónica; Barreiro, Rocío; Vázquez, Beatriz I; Cepeda, Alberto

    2017-04-01

    β-Agonists or β-adrenergic agonists are synthetic drugs sometimes used for therapeutic purposes in veterinary medicine. However, these compounds also belong to a class of illegal growth promoters that decrease the fat content in farm animals. The purpose of this study was to develop an analytical LC-MS/MS confirmatory method for the detection of nine β-agonists in bovine retina and liver tissues. The obtained CCα values ranged from 0.29 to 1.54 µg kg(-)(1) in retina and from 0.03 to 0.18 µg kg(-)(1) in liver, and CCβ values from 0.50 to 2.63 µg kg(-)(1) and from 0.05 to 0.30 µg kg(-)(1), respectively. Additionally, the importance of a matrix effect in these two tissues for the achievement of accurate detection of non-compliant samples was studied and discussed. It was concluded that the main characteristic of this phenomena is its considerable variability from one animal to another. Also, the total amount of matrix in the final extract can provide differences in the matrix-matched calibration line.

  20. Interlaboratory evaluation of an off-line supercritical fluid extraction/infrared spectrometric method for determination of petroleum hydrocarbons in solid matrixes

    SciTech Connect

    Lopez-Avila, V.; Young, R.; Kim, R.; Beckert, W.F. )

    1993-05-01

    A collaborative study was conducted, with 14 laboratories participating, to determine the method accuracy and precision of the proposed U.S. Environmental Protection Agency Methods 3560 and 8440. These methods involve the extraction of petroleum hydrocarbons from solid matrixes with supercritical carbon dioxide at 340 atm and 80 degrees C for 30 min (dynamic), collection of the extracted materials in tetrachloroethene (Method 3560), and analysis of the extracts by infrared (IR) spectrometry (Method 8440). The study design was based on the AOAC blind replicate design with balanced replicates. The study samples consisted of 4 solid matrixes that had petroleum hydrocarbon contents ranging from 614 to 32,600 mg/kg. Each of the 4 matrixes was extracted in triplicate, and the extracts were analyzed with 2 different IR spectrometers. In addition, each of the participating laboratories extracted a sample of unspiked clay soil, the same clay soil spiked with corn oil and reference oil at 1000 mg/kg each, and the same clay soil wetted to 30% water content and spiked with motor oil at 10,000 mg/kg (the latter 3 samples were extracted only once). Results indicated that the overall method accuracy for concentrations ranging from 614 to 32,600 mg/kg was 82.9%; the mean recoveries of petroleum hydrocarbons for each of the 4 solid matrixes ranged from 77.9 to 107% for analyses performed with the Perkin-Elmer Fourier transform IR spectrometer and from 75.9 to 101% for analyses performed with the Buck-Scientific IR spectrometer; the differences between the 2 instruments on a sample-by-sample basis were less than 17% for the total petroleum hydrocarbon determinations. The interlaboratory method precisions (RSDR) appeared to be matrix-dependent and ranged from 17.3 to 45.4% for analyses performed with the Perkin-Elmer Fourier transform IR spectrometer and from 16.7 to 47.9% for the Buck-Scientific IR spectrometer.

  1. Multimedia Matrix: A Cognitive Strategy for Designers.

    ERIC Educational Resources Information Center

    Sherry, Annette C.

    This instructional development project evaluates the effect of a matrix-based strategy to assist multimedia authors in acquiring and applying principles for effective multimedia design. The Multimedia Matrix, based on the Park and Hannafin "Twenty Principles and Implications for Interactive Multimedia" design, displays a condensed…

  2. Matrix-assisted diffusion-ordered spectroscopy: choosing a matrix.

    PubMed

    Gramosa, Nilce V; Ricardo, Nágila M S P; Adams, Ralph W; Morris, Gareth A; Nilsson, Mathias

    2016-06-07

    Diffusion-ordered spectroscopy (DOSY) is an important technique for separating the NMR signals of the components in a mixture, and relies on differences in diffusion coefficient. Standard DOSY experiments therefore struggle when the components of a mixture are of similar size, and hence diffuse at similar rates. Fortunately, the diffusion coefficients of solutes can be manipulated by changing the matrix in which they diffuse, using matrix components that interact differentially with them, a technique known as matrix-assisted DOSY. In the present investigation, we evaluate the performance of a number of new, previously used, and mixed matrices with an informative test mixture: the three positional isomers of dihydroxybenzene. The aim of this work is to present the matrix-assisted DOSY user with information about the potential utility of a set of matrices (and combinations of matrices), including ionic and non-ionic surfactants, complexing agents, polymers, and mixed solvents. A variety of matrices improved the diffusion resolution of the signals of the test system, with the best separation achieved by mixed micelles of sodium dodecyl sulfate and cetyl trimethylammonium bromide. The use of mixed matrices offers great potential for the analyst to tailor the matrix to a particular sample under study. © 2016 The Authors Magnetic Resonance in Chemistry Published by John Wiley & Sons, Ltd.

  3. The evaluation of the pyrochemistry for the treatment of Gen IV nuclear fuels Inert matrix chlorination studies in the gas phase or molten chloride salts

    NASA Astrophysics Data System (ADS)

    Bourg, S.; Péron, F.; Lacquement, J.

    2007-01-01

    The structure of the fuels for the future Gen IV nuclear reactors will be totally different from those of PWR, especially for the GFR concept including a closed cycle. In these reactors, fissile materials (carbides or nitrides of actinides) should be surrounded by an inert matrix. In order to build a reprocessing process scheme, the behavior of the potential inert matrices (silicon carbide, titanium nitride, and zirconium carbide and nitride) was studied by hydro- and pyrometallurgy. This paper deals with the chlorination results at high temperature by pyrometallurgy. For the first time, the reactivity of the matrix towards chlorine gas was assessed in the gas phase. TiN, ZrN and ZrC are very reactive from 400 °C whereas it is necessary to be over 900 °C for SiC to be as fast. In molten chloride melts, the bubbling of chlorine gas is less efficient than in gas phase but it is possible to attack the matrices. Electrochemical methods were also used to dissolve the refractory materials, leading to promising results with TiN, ZrN and ZrC. The massive SiC samples used were not conductive enough to be studied and in this case specific SiC-coated carbon electrodes were used. The key point of these studies was to find a method to separate the matrix compounds from the fissile material in order to link the head to the core of the process (electrochemical separation or liquid-liquid reductive extraction in the case of a pyrochemical reprocessing).

  4. Carbonate fuel cell matrix

    DOEpatents

    Farooque, Mohammad; Yuh, Chao-Yi

    1996-01-01

    A carbonate fuel cell matrix comprising support particles and crack attenuator particles which are made platelet in shape to increase the resistance of the matrix to through cracking. Also disclosed is a matrix having porous crack attenuator particles and a matrix whose crack attenuator particles have a thermal coefficient of expansion which is significantly different from that of the support particles, and a method of making platelet-shaped crack attenuator particles.

  5. Evaluation of matrix solid-phase dispersion (MSPD) extraction for multi-fenicols determination in shrimp and fish by liquid chromatography-electrospray ionisation tandem mass spectrometry.

    PubMed

    Tao, Yanfei; Zhu, Fangwei; Chen, Dongmei; Wei, Huimin; Pan, Yuanhu; Wang, Xu; Liu, Zhenli; Huang, Lingli; Wang, Yulian; Yuan, Zonghui

    2014-05-01

    A quantitative LC-MS/MS method was developed for the determination of chloramphenicol (CAP), thiamphenicol (TAP), florfenicol (FF) and florfenicol amine (FFA) in shrimp and fish. This rapid simple and effective extraction method was based on matrix solid-phase dispersion (MSPD). The best results were obtained using C18 as dispersant sorbent. The correlation coefficient (r) with each matrix-matched calibration curve is higher than 0.999 at the range of 0.05-0.8μg/kg for CAP and FF, 0.1-1.6μg/kg for FFA and TAP. CCα and CCβ of the fenicols upon the method were ranged from 0.01 to 0.09μg/kg and 0.04 to 0.25μg/kg respectively. In the fortified levels recoveries of the four compounds ranged from 83.8% to 98.8% with RSDs lower than 13.7%. The proposed method has been applied successfully to the analysis of CAP, TAP, FF and FFA in shrimp and fish samples, which demonstrates that this method is fast, sensitive, reliable and environmental friendly.

  6. Evaluation of the drug solubility and rush ageing on drug release performance of various model drugs from the modified release polyethylene oxide matrix tablets.

    PubMed

    Shojaee, Saeed; Nokhodchi, Ali; Maniruzzaman, Mohammed

    2017-02-01

    Hydrophilic matrix systems are currently some of the most widely used drug delivery systems for controlled-release oral dosage forms. Amongst a variety of polymers, polyethylene oxide (PEO) is considered an important material used in pharmaceutical formulations. As PEO is sensitive to thermal oxidation, it is susceptible to free radical oxidative attack. The aim of this study was to investigate the stability of PEO based formulations containing different model drugs with different water solubility, namely propranolol HCl, theophylline and zonisamide. Both polyox matrices 750 and 303 grade were used as model carriers for the manufacture of tablets stored at 40 °C. The results of the present study suggest that the drug release from the matrix was affected by the length of storage conditions, solubility of drugs and the molecular weight of the polymers. Generally, increased drug release rates were prevalent in soluble drug formulations (propranolol) when stored at the elevated temperature (40 °C). In contrast, it was not observed with semi soluble (theophylline) and poorly soluble (zonisamide) drugs especially when formulated with PEO 303 polymer. This indicates that the main parameters controlling the drug release from fresh polyox matrices are the solubility of the drug in the dissolution medium and the molecular weight of the polymer. DSC traces indicated that that there was a big difference in the enthalpy and melting points of fresh and aged PEO samples containing propranolol, whereas the melting point of the aged polyox samples containing theophylline and zonisamide was unaffected. Graphical abstract ᅟ.

  7. Evaluation of Stress-Induced Microbial Siderophore from Pseudomonas aeruginosa Strain S1 as a Potential Matrix Metalloproteinase Inhibitor in Wound Healing Applications.

    PubMed

    Thyagarajan, Sita Lakshmi; Kandhasamy, S; Ramanathan, Giriprasath; Sivagnanam, Uma Tiruchirapalli; Perumal, P T

    2016-05-01

    Matrix metalloproteinases (MMPs) are zinc-dependent proteolytic enzymes capable of causing various inflammatory and various degenerative diseases if over-expressed. The active site of these enzymes is a zinc binding motif which binds to the specific site on the substrate and induce degradation. Hence an inhibitor is required to form a complex with zinc motif which hampers the binding ability of MMPs. To obtain novel MMPs inhibitor for wound healing, the chelating activity of siderophore from the microbial source was focused. During screening for siderophore production, strain S1 produced the highest amount of siderophore in the minimal salts medium. The isolate was confirmed as Pseudomonas aeruginosa strain S1 based on 16S rRNA gene sequencing and phylogenetic analysis. The activity of the siderophore was assayed using chrome azurol sulphonate and purified by the chromatographic techniques. The structural evidence through Fourier transform infrared and nuclear magnetic resonance spectra revealed that the isolated siderophore is a catecholate type with the distinctive characters. The positive results of calcein and fluozin-3 assays indicate that siderophore could bind to divalent metal ions, namely Fe(2+) and Zn(2+). As the siderophore compound focused on wound healing property, the in vitro studies revealed the viability of NH3T3 fibroblast cells and its efficiency in matrix modulating was confirmed through gelatin zymogram.

  8. Matrix with Prescribed Eigenvectors

    ERIC Educational Resources Information Center

    Ahmad, Faiz

    2011-01-01

    It is a routine matter for undergraduates to find eigenvalues and eigenvectors of a given matrix. But the converse problem of finding a matrix with prescribed eigenvalues and eigenvectors is rarely discussed in elementary texts on linear algebra. This problem is related to the "spectral" decomposition of a matrix and has important technical…

  9. The intraclass covariance matrix.

    PubMed

    Carey, Gregory

    2005-09-01

    Introduced by C.R. Rao in 1945, the intraclass covariance matrix has seen little use in behavioral genetic research, despite the fact that it was developed to deal with family data. Here, I reintroduce this matrix, and outline its estimation and basic properties for data sets on pairs of relatives. The intraclass covariance matrix is appropriate whenever the research design or mathematical model treats the ordering of the members of a pair as random. Because the matrix has only one estimate of a population variance and covariance, both the observed matrix and the residual matrix from a fitted model are easy to inspect visually; there is no need to mentally average homologous statistics. Fitting a model to the intraclass matrix also gives the same log likelihood, likelihood-ratio (LR) chi2, and parameter estimates as fitting that model to the raw data. A major advantage of the intraclass matrix is that only two factors influence the LR chi2--the sampling error in estimating population parameters and the discrepancy between the model and the observed statistics. The more frequently used interclass covariance matrix adds a third factor to the chi2--sampling error of homologous statistics. Because of this, the degrees of freedom for fitting models to an intraclass matrix differ from fitting that model to an interclass matrix. Future research is needed to establish differences in power-if any--between the interclass and the intraclass matrix.

  10. Sloan Digital Sky Survey Photometric Calibration Revisited

    SciTech Connect

    Marriner, John; /Fermilab

    2012-06-29

    The Sloan Digital Sky Survey calibration is revisited to obtain the most accurate photometric calibration. A small but significant error is found in the flat-fielding of the Photometric telescope used for calibration. Two SDSS star catalogs are compared and the average difference in magnitude as a function of right ascension and declination exhibits small systematic errors in relative calibration. The photometric transformation from the SDSS Photometric Telescope to the 2.5 m telescope is recomputed and compared to synthetic magnitudes computed from measured filter bandpasses.

  11. Revisiting the texture zero neutrino mass matrices

    NASA Astrophysics Data System (ADS)

    Singh, Madan; Ahuja, Gulsheen; Gupta, Manmohan

    2016-12-01

    In the light of refined and large measurements of the reactor mixing angle θ, we have revisited the texture three- and two-zero neutrino mass matrices in the flavor basis. For Majorana neutrinos, it has been explicitly shown that all the texture three-zero mass matrices remain ruled out. Further, for both normal and inverted mass ordering, for the texture two-zero neutrino mass matrices one finds interesting constraints on the Dirac-like CP-violating phase δ and Majorana phases ρ and σ.

  12. The Holstein polaron problem revisited

    NASA Astrophysics Data System (ADS)

    Tayebi, Amin; Zelevinsky, Vladimir

    2016-06-01

    The Holstein Hamiltonian was proposed half a century ago; since then, decades of research have come up empty handed in the pursuit of a closed-form solution. An exact solution to the two-site Holstein model is presented in this paper. The obtained results provide a clear image of the Hamiltonian structure and allow for the investigation of the symmetry, energy level crossings and polaronic characteristics of the system. The main mathematical tool is a three-term recurrence relation between the wave function amplitudes, which was obtained using the properties of a family of orthogonal functions, namely the Poisson-Charlier polynomials. It is shown that, with the appropriate choice of basis, the eigenfunctions of the problem naturally fall into two families (parities) associated with the discrete {{{Z}}}2 symmetry of the Hamiltonian. The asymptotic solution to the recurrence relation is found by using the Birkhoff expansion. The asymptotic sets the truncation criterion for the wave function, which ensures the accurate calculation of the energy levels for any strength of electron-phonon interaction. The level crossing of states with different parities is discussed and the exact points of broken symmetry are found analytically. The results are used as the building blocks for studying a four-site system. The inherited symmetries lead to the formation of a sparse matrix that is convenient for numerical calculations.

  13. Evaluation of the Bruker Biotyper Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry System for Identification of Blood Isolates of Vibrio Species

    PubMed Central

    Cheng, Wern-Cherng; Jan, I-Shiow; Chen, Jong-Min; Teng, Shih-Hua; Teng, Lee-Jene; Sheng, Wang-Huei; Ko, Wen-Chien

    2015-01-01

    Among 56 blood isolates of Vibrio species identified by sequencing analysis of 16S rRNA and rpoB genes, the Bruker Biotyper matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) system correctly identified all isolates of Vibrio vulnificus (n = 20), V. parahaemolyticus (n = 2), and V. fluvialis (n = 1) but none of the isolates of serogroup non-O1/O139 (non-serogroup O1, non-O139) V. cholerae (n = 33) to the species level. All of these serogroup non-O1/O139 V. cholerae isolates were correctly identified using the newly created MALDI-TOF MS database. PMID:25740773

  14. Evaluation of the mechanical properties of conventionally-cast Al matrix composites reinforced by quasicrystalline Al-Cu-Fe particles using continuous ball indentation technique

    NASA Astrophysics Data System (ADS)

    Fleury, E.; Lee, S. M.; Kim, W. T.; Kim, D. H.

    2000-10-01

    Room temperature mechanical properties of the Al/(AlCuFe)p and Al96Cu4/(AlCuFe)p cast composites were estimated from uniaxial compressive test and continuous ball indentation technique. Values of the Young's modulus and yield stress determined from continuous ball indentation tests were slightly overestimated, suggesting a surface effect on the mechanical properties. However, it was shown that the Al-Cu-Fe particles provided a significant increase of the elastic modulus, yield stress, and strain hardening, especially in the range up to 10% volume fraction of reinforcements. Also, determination of the hardness by continuous-ball-indentation tests revealed a strong influence of the matrix strength on the mechanical properties of the conventionally cast composites.

  15. Nanocrystal doped matrixes

    DOEpatents

    Parce, J. Wallace; Bernatis, Paul; Dubrow, Robert; Freeman, William P.; Gamoras, Joel; Kan, Shihai; Meisel, Andreas; Qian, Baixin; Whiteford, Jeffery A.; Ziebarth, Jonathan

    2010-01-12

    Matrixes doped with semiconductor nanocrystals are provided. In certain embodiments, the semiconductor nanocrystals have a size and composition such that they absorb or emit light at particular wavelengths. The nanocrystals can comprise ligands that allow for mixing with various matrix materials, including polymers, such that a minimal portion of light is scattered by the matrixes. The matrixes of the present invention can also be utilized in refractive index matching applications. In other embodiments, semiconductor nanocrystals are embedded within matrixes to form a nanocrystal density gradient, thereby creating an effective refractive index gradient. The matrixes of the present invention can also be used as filters and antireflective coatings on optical devices and as down-converting layers. Processes for producing matrixes comprising semiconductor nanocrystals are also provided. Nanostructures having high quantum efficiency, small size, and/or a narrow size distribution are also described, as are methods of producing indium phosphide nanostructures and core-shell nanostructures with Group II-VI shells.

  16. On the evaluation of nonadiabatic coupling matrix elements for MCSCF/CI wave functions. IV. Second derivative terms using analytic gradient methods

    NASA Astrophysics Data System (ADS)

    Saxe, Paul; Yarkony, David R.

    1987-01-01

    A recently proposed methodology for determining second derivative nonadiabatic coupling matrix elements h(J,I,Rα,R) ≡<ΨJ(r;R)‖(∂2/∂R2α )ΨI(r;R)>r based on analytic gradient methods is implemented and discussed. Here r denotes the electronic coordinates, R the nuclear coordinates, and the ΨJ (r;R) are eigenfunctions of the nonrelativistic Born-Oppenheimer Hamiltonian at the state averaged MCSCF/CI level. The region of a conical intersection of the 1,2 2A' potential energy surfaces of the Li-H2 system is considered in order to illustrate the potential of this approach. The relation between h(J,I,Rα,R) and the first derivative matrix elements g(J,I,Rα,R) ≡<ΨJ(r;R)‖(∂/∂Rα)ΨI (r;R)>r is considered and the role of symmetry discussed. The h(J,I,Rα,R) are analyzed in terms of contributions from molecular orbital and CI coefficient derivatives and the importance of the various nuclear degree of freedom, Rα, is considered. It is concluded that for the case considered a flexible multiconfiguration wave function is desirable for characterizing h(J,I,Rα,R). This methodology complements recent advances in treating nonadiabatic processes for diatomic and triatomic systems starting with adiabatic states, including the work of Mead, Truhlar, and co-workers on conical (Jahn-Teller) intersections in X3 systems, by providing an essential computational step for the ab initio characterization the relevant electronic structure parameters.

  17. Sustained-release effervescent floating matrix tablets of baclofen: development, optimization and in vitro-in vivo evaluation in healthy human volunteers

    PubMed Central

    Gande, S

    2011-01-01

    Background and the purpose of the study Baclofen, a centrally acting skeletal muscle relaxant, is indicated in the long-term treatment of spasticity. It is difficult to formulate baclofen sustained release dosage forms because its absorption on arrival to colon (or even before) is low or nonexistent. In the present investigation efforts were made to improve the bioavailability of baclofen by increasing the residence time of the drug through sustained-release matrix tablet formulation via gastroretentive mechanism. Methods Tablets were prepared by wet granulation technique. The influence of gas generating and gel forming agents, amount of baclofen and total weight of tablet on physical properties, in vitro buoyancy, floating lag time, drug release, DSC, X-ray studies were investigated. The release mechanisms were explored and explained by applying zero order, first order, Higuchi and Korsmeyer equations. The selected formulations were subjected to stability study for the period of three months. Results For all formulations, kinetics of drug release from tablet followed Higuchi's square root of time kinetic treatment heralding diffusion as predominant mechanism of drug release. Formulations containing 20 mg and 40 mg (F-1 and F-7) showed similar release profiles. There was no significant change in the selected formulations, when subjected to accelerated stability conditions over a period of three months. X-ray imaging in six healthy human volunteers revealed a mean gastric retention period of 5.50±0.7 hrs for the selected formulation. Conclusion Stable, sustained release effervescent floating matrix tablets of baclofen could be prepared by wet granulation technique. PMID:22615658

  18. Evaluation of a recent product to remove lipids and other matrix co-extractives in the analysis of pesticide residues and environmental contaminants in foods.

    PubMed

    Han, Lijun; Matarrita, Jessie; Sapozhnikova, Yelena; Lehotay, Steven J

    2016-06-03

    This study demonstrates the application of a novel lipid removal product to the residue analysis of 65 pesticides and 52 environmental contaminants in kale, pork, salmon, and avocado by fast, low pressure gas chromatography - tandem mass spectrometry (LPGC-MS/MS). Sample preparation involves QuEChERS extraction followed by use of EMR-Lipid ("enhanced matrix removal of lipids") and an additional salting out step for cleanup. The optimal amount of EMR-Lipid was determined to be 500mg for 2.5mL extracts for most of the analytes. The co-extractive removal efficiency by the EMR-Lipid cleanup step was 83-98% for fatty samples and 79% for kale, including 76% removal of chlorophyll. Matrix effects were typically less than ±20%, in part because analyte protectants were used in the LPGC-MS/MS analysis. The recoveries of polycyclic aromatic hydrocarbons and diverse pesticides were mostly 70-120%, whereas recoveries of nonpolar polybrominated diphenyl ethers and polychlorinated biphenyls were mostly lower than 70% through the cleanup procedure. With the use of internal standards, method validation results showed that 76-85 of the 117 analytes achieved satisfactory results (recoveries of 70-120% and RSD≤20%) in pork, avocado, and kale, while 53 analytes had satisfactory results in salmon. Detection limits were 5-10ng/g for all but a few analytes. EMR-Lipid is a new sample preparation tool that serves as another useful option for cleanup in multiresidue analysis, particularly of fatty foods.

  19. A parable of oil and water: Revisiting Prince William Sound, four years after

    SciTech Connect

    Keeble, J.

    1993-12-31

    On Good Friday, March 24, 1989, the Exxon oil tanker Valdez foundered on Bligh Reef, spilling 11 million gallons of crude oil into Alaska`s Prince William Sound. To Alaskans, especially fishing people, this was a shocking but not entirely unanticipated event, as there had been several near misses in the twelve years since the opening of oil shipping from Valdez, Alaska. This article revisits Prince William sound to evaluate both the lingering environmental effects and the socio-economic effects of the spill and the huge monetary settlement from the spills.

  20. Effective Career Exploration Programs Revisited.

    ERIC Educational Resources Information Center

    Wiggins, James D.

    1987-01-01

    Replicated findings of Wiggins and Moody (1981). Evaluated four types of high school career exploration programs: cluster (N=53), Career Maturity Inventory (N=52), Career Survey (N=57), and Self-Directed Search/Vocational Preference Inventory (N=55). Results favored latter three programs which allowed students to pursue their own interests instead…

  1. Statistical evaluation of the influence of soil properties on recoveries and matrix effects during the analysis of pharmaceutical compounds and steroids by quick, easy, cheap, effective, rugged and safe extraction followed by liquid chromatography-tandem mass spectrometry.

    PubMed

    Salvia, Marie-Virginie; Cren-Olivé, Cécile; Vulliet, Emmanuelle

    2013-11-08

    Numerous chemical products are dispersed in our environment. Many of them are recognized as harmful to humans and the ecosystem. Among these harmful substances are antibiotics and steroid hormones. Currently, very few data are available on the presence and fate of these substances in the environment, in particular for solid matrices, mainly due to a lack of analytical methodologies. Indeed, soil is a very complex matrix, and the nature and composition of the soil has a significant impact on the extraction efficiency and the sensitivity of the method. For this reason a statistical approach was performed to study the influence of soil parameters (clay, silt, sand and organic carbon percentages and cation exchange capacity (CEC)) on recoveries and matrix effects of various pharmaceuticals and steroids. Thus, an analysis of covariance (ANCOVA) was performed when several substances were analyzed simultaneously, whereas a Pearson correlation was used to study the compounds individually. To the best of our knowledge, this study is the first time such an experiment was performed. The results showed that clay and organic carbon percentages as well as the CEC have an impact on the recoveries of most of the target substances, the variables being anti-correlated. This result suggests that the compounds are trapped in soils with high levels of clay and organic carbon and a high CEC. For the matrix effects, it was shown that the organic carbon content has a significant effect on steroid hormones and penicillin G matrix effects (positive correlation). Finally, interaction effects (first order) were evaluated. This latter point corresponds to the crossed effects that occur between explanatory variables (soil parameters). Indeed, the value taken by an explanatory variable can have an influence on the effect that another explanatory variable has on a dependent variable. For instance, it was shown that some parameters (silt, sand) have an impact on the effect that clay content has on

  2. Hybridized polymer matrix composites

    NASA Technical Reports Server (NTRS)

    House, E. E.; Hoggatt, J. T.; Symonds, W. A.

    1980-01-01

    The extent to which graphite fibers are released from resin matrix composites that are exposed to fire and impact conditions was determined. Laboratory simulations of those conditions that could exist in the event of an aircraft crash and burn situation were evaluated. The effectiveness of various hybridizing concepts in preventing this release of graphite fibers were also evaluated. The baseline (i.e., unhybridized) laminates examined were prepared from commercially available graphite/epoxy, graphite/polyimide, and graphite/phenolic materials. Hybridizing concepts investigated included resin fillers, laminate coatings, resin blending, and mechanical interlocking of the graphite reinforcement. The baseline and hybridized laminates' mechanical properties, before and after isothermal and humidity aging, were also compared. It was found that a small amount of graphite fiber was released from the graphite/epoxy laminates during the burn and impact conditions used in this program. However, the extent to which the fibers were released is not considered a severe enough problem to preclude the use of graphite reinforced composites in civil aircraft structure. It also was found that several hybrid concepts eliminated this fiber release. Isothermal and humidity aging did not appear to alter the fiber release tendencies.

  3. Hershfield factor revisited: Correcting annual maximum precipitation

    NASA Astrophysics Data System (ADS)

    Papalexiou, Simon Michael; Dialynas, Yannis G.; Grimaldi, Salvatore

    2016-11-01

    The Hershfield factor (H) is a multiplier aiming to correct the error between fixed time interval maxima (F-maxima) and sliding maxima (S-maxima) as a direct consequence of temporal discretization of hydrometeorological time series. Rainfall is typically recorded over discrete intervals, e.g., over fixed 24-h intervals, and the historical series express average values over these intervals. This temporal discretization introduces an important systematic error on rainfall characteristics such as the annual maxima. Research to date suggests that our understanding of this error across different time scales is limited. In this study we revisit the probabilistic nature of the H-factor in an unprecedentedly large analysis comprising thousands of up-to-date hourly records across the US. We study the probabilistic behavior of F- and S-maxima of the historical records. We quantify the discretization error of the rainfall maxima and its statistical properties at different time scales. We revisit the classical definitions of the H-factor and we investigate the exact probability distribution of H-factor. We introduce a bounded exponential distribution with an atom at one, which closely depicts the empirical distribution of the H-factor. Notable is the result that the proposed mixed-type distribution is invariant across a range of time scales. This work clarifies the probabilistic nature of the rainfall maxima correction. The results may have wide use across a range of hydrological applications.

  4. AB289. SPR-16 A preliminary evaluation of vaginal alignment following a transvaginal procedure using MatriStem™ pelvic floor matrix in the rhesus macaque

    PubMed Central

    Easley, Deanna C.; Barone, William R.; Moalli, Pamela A.; Abramowitch, Steven D.

    2016-01-01

    Objective Implantation of biological or synthetic mesh is the most common method of surgical intervention for pelvic organ prolapse, however, complications ensuing from these surgical repairs occur in 15.5% of cases. MatristemTM (ACell, Inc., USA) Pelvic Floor Matrix is a urinary bladder matrix (UBM) device indicated for transvaginal repair. This device is remodeled and replaced by host tissue following implantation, which raises the concern that the process may result in a loss of support to the vagina. Thus, the goal of this study was to quantify measurable changes in vaginal alignment via magnetic resonance imaging (MRI) before (pre) and after (10 days and 3 months) a transvaginal procedure with this device in a rhesus macaque model. Methods Two rhesus macaques underwent a transvaginal procedure in accordance with the IACUC at the University of Pittsburgh (protocol #13081928). Level 1 & 2 support to the vagina was transected to simulate compromised support. Two sheets of 6-ply MatriStemTM were implanted to support the anterior and posterior vagina. Vaginal alignment was derived from MRIs taken pre, 10 days, and 3 months after surgery. The border of the vagina was manually traced, and used to calculate the centroid of each tracing. These centroids represent the path of the vagina through the pelvis. Further, a 3D coordinate system was mapped to the pelvis, and lines fit to the proximal and distal vagina were used to measure the angle of each line with respect to a cephalic oriented axis in the mid-sagittal plane, which is referred to as the angle of elevation. Results At 10 days, the angle of elevation became more acute by 8.6% and 17%, respectively. These changes reflect expectations of a tensioned transvaginal fixation of the vagina. At 3 months post-surgery, angles of elevation approached pre surgery conditions, indicating that MatriStemTM was providing a comparable level of support to native tissue, even following remodeling. Conclusions This preliminary

  5. The jugular venous pressure revisited

    PubMed Central

    CHIACO, JOHN MICHAEL S. CHUA; PARIKH, NISHA I.; FERGUSSON, DAVID J.

    2016-01-01

    Assessment of the jugular venous pressure is often inadequately performed and undervalued. Here, we review the physiologic and anatomic basis for the jugular venous pressure, including the discrepancy between right atrial and central venous pressures. We also describe the correct method of evaluating this clinical finding and review the clinical relevance of the jugular venous pressure, especially its value in assessing the severity and response to treatment of congestive heart failure. Waveforms reflective of specific conditions are also discussed. PMID:24085809

  6. Use of synthetic data to evaluate positive matrix factorization as a source apportionment tool for PM2.5 exposure data.

    PubMed

    Brinkman, Gregory; Vance, Gary; Hannigan, Michael P; Milford, Jana B

    2006-03-15

    Positive matrix factorization (PMF) was applied to synthetic datasets that simulate personal exposures to airborne PM2.5 from 12 sources. Three differentfilter analysis scenarios using different analytical chemistry techniques were considered. The full suite scenario quantified elemental carbon, organic carbon, inorganic ions, trace elements, and trace organic species including carboxylic acids and organic compounds with -OH functionality. A second scenario excluded trace elements and a third assumed that derivatization steps to quantify polar organic compounds were not performed. Similar errors in source apportionment were seen with all three scenarios. In most cases, PMF failed to separate out factors corresponding to road dust and vegetative debris, two sources that made relatively uniform contributions to the synthetic exposures. Factors representing wood smoke, natural gas combustion, and meat cooking sources were difficult to identify due to a lack of unique tracers with concentrations reliably above the detection limits assumed in the study. Factors representing cigarette smoke, candle smoke, gasoline exhaust, and secondary aerosols were comparatively easy to identify. When contributions from a pair of sources, such as diesel and gasoline exhaust, were highly correlated in the synthetic datasets, a single factor corresponding to both sources was usually found.

  7. Design, synthesis, and biological evaluation of novel matrix metalloproteinase inhibitors as potent antihemorrhagic agents: from hit identification to an optimized lead.

    PubMed

    Orbe, Josune; Sánchez-Arias, Juan A; Rabal, Obdulia; Rodríguez, José A; Salicio, Agustina; Ugarte, Ana; Belzunce, Miriam; Xu, Musheng; Wu, Wei; Tan, Haizhong; Ma, Hongyu; Páramo, José A; Oyarzabal, Julen

    2015-03-12

    Growing evidence suggests that matrix metalloproteinases (MMP) are involved in thrombus dissolution; then, considering that new therapeutic strategies are required for controlling hemorrhage, we hypothesized that MMP inhibition may reduce bleeding by delaying fibrinolysis. Thus, we designed and synthesized a novel series of MMP inhibitors to identify potential candidates for acute treatment of bleeding. Structure-based and knowledge-based strategies were utilized to design this novel chemical series, α-spiropiperidine hydroxamates, of potent and soluble (>75 μg/mL) pan-MMP inhibitors. The initial hit, 12, was progressed to an optimal lead 19d. Racemic 19d showed a remarkable in vitro phenotypic response and outstanding in vivo efficacy; in fact, the mouse bleeding time at 1 mg/kg was 0.85 min compared to 29.28 min using saline. In addition, 19d displayed an optimal ADME and safety profile (e.g., no thrombus formation). Its corresponding enantiomers were separated, leading to the preclinical candidate 5 (described in Drug Annotations series, J. Med. Chem. 2015, ).

  8. Simultaneous determination of 13 phytohormones in oilseed rape tissues by liquid chromatography-electrospray tandem mass spectrometry and the evaluation of the matrix effect.

    PubMed

    Fan, Sufang; Wang, Xiupin; Li, Peiwu; Zhang, Qi; Zhang, Wen

    2011-03-01

    In the experiment, a high-performance liquid chromatography and electrospray ionization-tandem mass spectrometry with selected reaction monitoring was used to simultaneously determine various classes of phytohormones, including indole-3-acetic acid, α-naphthaleneacetic acid, 2-chlorobenzoic acid, 4-chlorobenzoic acid, indole-3-butyric acid, gibberellic acid, 2,4-dichlorophenoxyacetic acid, 2-naphthoxyacetic acid, abscisic acid, 2,3,5-triiodobenzoic acid, uniconazole, paclobutrazol and 2,4-epibassinolide in rape tissues. The analyses were separated by an HPLC equipped with a reversed-phase column using a binary solvent system composed of methanol and water, both containing 0.1% of formic acid. The matrix effect was also considered and determined. The technology was applied to analyze rape tissues, including roots, stems, leaves, flowers, immature pods and rape seeds. The rape tissues were subjected to ultrasound-assisted extraction and purified by dispersive solid-phase extraction, and then transferred into the liquid chromatography system. The detection limit for each plant hormone was defined by the ratio of signal/background noise (S/N) of 3. The results showed perfect linearity (R(2) values of 0.9987-1.0000) and reproducibility of elution times (relative standard deviations, RSDs,<1%) and peak areas (RSDs,<7%) for all target compounds.

  9. Biofilm Matrix Proteins

    PubMed Central

    Fong, Jiunn N. C.; Yildiz, Fitnat H.

    2015-01-01

    Proteinaceous components of the biofilm matrix include secreted extracellular proteins, cell surface adhesins and protein subunits of cell appendages such as flagella and pili. Biofilm matrix proteins play diverse roles in biofilm formation and dissolution. They are involved in attaching cells to surfaces, stabilizing the biofilm matrix via interactions with exopolysaccharide and nucleic acid components, developing three-dimensional biofilm architectures, and dissolving biofilm matrix via enzymatic degradation of polysaccharides, proteins, and nucleic acids. In this chapter, we will review functions of matrix proteins in a selected set of microorganisms, studies of the matrix proteomes of Vibrio cholerae and Pseudomonas aeruginosa, and roles of outer membrane vesicles and of nucleoid-binding proteins in biofilm formation. PMID:26104709

  10. Effective-Medium Models for Marine Gas Hydrates, Mallik Revisited

    NASA Astrophysics Data System (ADS)

    Terry, D. A.; Knapp, C. C.; Knapp, J. H.

    2011-12-01

    Hertz-Mindlin type effective-medium dry-rock elastic models have been commonly used for more than three decades in rock physics analysis, and recently have been applied to assessment of marine gas hydrate resources. Comparisons of several effective-medium models with derivative well-log data from the Mackenzie River Valley, Northwest Territories, Canada (i.e. Mallik 2L-38 and 5L-38) were made several years ago as part of a marine gas hydrate joint industry project in the Gulf of Mexico. The matrix/grain supporting model (one of the five models compared) was clearly a better representation of the Mallik data than the other four models (2 cemented sand models; a pore-filling model; and an inclusion model). Even though the matrix/grain supporting model was clearly better, reservations were noted that the compressional velocity of the model was higher than the compressional velocity measured via the sonic logs, and that the shear velocities showed an even greater discrepancy. Over more than thirty years, variations of Hertz-Mindlin type effective medium models have evolved for unconsolidated sediments and here, we briefly review their development. In the past few years, the perfectly smooth grain version of the Hertz-Mindlin type effective-medium model has been favored over the infinitely rough grain version compared in the Gulf of Mexico study. We revisit the data from the Mallik wells to review assertions that effective-medium models with perfectly smooth grains are a better predictor than models with infinitely rough grains. We briefly review three Hertz-Mindlin type effective-medium models, and standardize nomenclature and notation. To calibrate the extended effective-medium model in gas hydrates, we use a well accepted framework for unconsolidated sediments through Hashin-Shtrikman bounds. We implement the previously discussed effective-medium models for saturated sediments with gas hydrates and compute theoretical curves of seismic velocities versus gas hydrate

  11. Automatic switching matrix

    DOEpatents

    Schlecht, Martin F.; Kassakian, John G.; Caloggero, Anthony J.; Rhodes, Bruce; Otten, David; Rasmussen, Neil

    1982-01-01

    An automatic switching matrix that includes an apertured matrix board containing a matrix of wires that can be interconnected at each aperture. Each aperture has associated therewith a conductive pin which, when fully inserted into the associated aperture, effects electrical connection between the wires within that particular aperture. Means is provided for automatically inserting the pins in a determined pattern and for removing all the pins to permit other interconnecting patterns.

  12. Teaching Improvement Model Designed with DEA Method and Management Matrix

    ERIC Educational Resources Information Center

    Montoneri, Bernard

    2014-01-01

    This study uses student evaluation of teachers to design a teaching improvement matrix based on teaching efficiency and performance by combining management matrix and data envelopment analysis. This matrix is designed to formulate suggestions to improve teaching. The research sample consists of 42 classes of freshmen following a course of English…

  13. Finite size effect on classical ideal gas revisited

    NASA Astrophysics Data System (ADS)

    Ghosh, P.; Ghosh, S.; Mitra, J.; Bera, N.

    2015-09-01

    Finite size effects on classical ideal gas are revisited. The micro-canonical partition function for a collection of ideal particles confined in a box is evaluated using Euler-Maclaurin’s as well as Poisson's summation formula. In Poisson's summation formula there are some exponential terms which are absent in Euler-Maclaurin’s formula. In the thermodynamic limit the exponential correction is negligibly small but in the macro/nano dimensions and at low temperatures they may have a great significance. The consequences of finite size effects have been illustrated by redoing the calculations in one and three dimensions keeping the exponential corrections. Global and local thermodynamic properties, diffusion driven by the finite size effect, and effect on speed of sound have been discussed. Thermo-size effects, similar to thermoelectric effects, have been described in detail and may be a theoretical basis with which to design nano-scaled devices. This paper can also be very helpful for undergraduate and graduate students in physics and chemistry as an instructive exercise for a good course in statistical mechanics.

  14. Gastroretentive Matrix Tablets of Boswellia Oleogum Resin: Preparation, Optimization, In Vitro Evaluation, and Cytoprotective Effect on Indomethacin-Induced Gastric Ulcer in Rabbits.

    PubMed

    Yusif, Rehab Mohammad; Abu Hashim, Irhan Ibrahim; Mohamed, Elham Abdelmonem; Badria, Farid Abd-Elreheim

    2016-04-01

    Currently available anti-ulcer drugs suffer from serious side effects which limited their uses and prompted the need to search for a safe and efficient new anti-ulcer agent. Boswellia gum resin (BR) emerged as a safe, efficient, natural, and economic potential cytoprotective agent. Thus, it is of medical importance to develop gastroretentive (GR) formulations of BR to enhance its bioavailability and anti-ulcer efficacy. Early attempts involved the use of organic solvents and non-applicability to large-scale production. In this study, different tablet formulations were prepared by simple direct compression combining floating and bioadhesion mechanisms employing hydroxypropyl methylcellulose (HPMC), sodium carboxymethyl cellulose (SCMC), pectin (PC), and/or carbopol (CP) as bioadhesive polymers and sodium bicarbonate (SB) as a gas former. The prepared tablets were subjected for assessment of swelling, floating, bioadhesion, and drug release in 0.1 N HCl. The optimized GR formulation was examined for its protective effect on the gastric ulcer induced by indomethacin in albino rabbits compared with lactose tablets. The obtained results disclosed that swelling, floating, bioadhesion, and drug release of the GR tablets of BR depend mainly on the nature of the matrix and the ratio of polymer combinations. Moreover, a combination of SCMC-CP in a ratio of 2:1 (SCP21) exhibited desirable floating, bioadhesion, swelling, and extended drug release. Also, a 6-h pretreatment with SCP21 tablets decreased the severity of inflammation and number of bleeding spots among ulcer-induced rabbits in comparison to those treated with lactose tablets.

  15. A comparative evaluation of the effectiveness of subpedicle acellular dermal matrix allograft with subepithelial connective tissue graft in the treatment of isolated marginal tissue recession: A clinical study

    PubMed Central

    Shori, Tony; Kolte, Abhay; Kher, Vishal; Dharamthok, Swarup; Shrirao, Tushar

    2013-01-01

    Introduction: The most common problem encountered in our day to day practice is exposed root surface or a tooth getting long. The main indication for root coverage procedures are esthetics and/or cosmetic demands followed by the management of root hypersensitivity, root caries or when it hampers proper plaque removal. Over the years, various techniques have been used to achieve root coverage. Aim and Objectives: The aim of this study was to compare the effectiveness of subpedicle acellular dermal matrix allograft (ADMA) with subepithelial connective tissue graft (SCTG) in the treatment of isolated marginal tissue recession. Materials and Methods: Twenty systemically healthy patients aged between 18 to 50 years (mean age29.7±4.35 years) with a recession defect on the labial and the buccal surfaces of any teeth were selected for the study. Ten patients received the test treatment (ADMA), ten patients received the control treatment (SCTG). Clinical recordings assessed at baseline, three months and six months post surgery, included Plaque index (PI), Papillary bleeding index (PBI), Gingival recession (REC), Probing pocket depth (PPD), Clinical attachment level (CAL) and Width of keratinized gingival (WKG). Results: Test group (ADMA) showed 86.93% mean root coverage while control group (SCTG) showed 84.72% at six months post surgery. Mean increase in the width of keratinized gingiva was significantly greater in the SCTG group (3.3±0.48mm) compared to ADMA group (2.4±0.51mm). Conclusion: Both the treatment produced a significant reduction in gingival recession and probing pocket depth and significant gain in clinical attachment level and width of keratinised gingiva. PMID:23633778

  16. Hypertriglyceridemia and Cardiovascular Diseases: Revisited

    PubMed Central

    Han, Seung Hwan; Nicholls, Stephen J; Sakuma, Ichiro; Zhao, Dong

    2016-01-01

    Residual cardiovascular risk and failure of high density lipoprotein cholesterol raising treatment have refocused interest on targeting hypertriglyceridemia. Hypertriglyceridemia, triglyceride-rich lipoproteins, and remnant cholesterol have demonstrated to be important risk factors for cardiovascular disease; this has been demonstrated in experimental, genetic, and epidemiological studies. Fibrates can reduce cardiovascular event rates with or without statins. High dose omega-3 fatty acids continue to be evaluated and new specialized targeting treatment modulating triglyceride pathways, such as inhibition of apolipoprotein C-III and angiopoietin-like proteins, are being tested with regard to their effects on lipid profiles and cardiovascular outcomes. In this review, we will discuss the role of hypertriglyceridemia, triglyceride-rich lipoproteins and remnant cholesterol on cardiovascular disease, and the potential implications for treatment stargeting hypertriglyceridemia. PMID:27014342

  17. Toynbee revisited: eustachian tubal sonograph.

    PubMed

    Wilson, H L

    1982-01-01

    The ETS represents a modern version of the Toynbee tube. The ETS replaces the tube with sophisticated electronic equipment that amplifies and records the sounds of air entering the middle ear. The results of the test correlate well with the clinical behavior of the eustachian tube. The ETS does this by permitting the auditory tube to function in its normal state. It requires minimal patient response and does not require a soundproof room. It allows performance of the Toynbee, Politzer, and Valsalva maneuvers with the equipment in place and does not interfere with catheterization of the tubal orifice. Medications may be applied to the nose and nasopharynx or be given parenterally while the sonograph is in place. Thus far, it appears that the ETS is very useful in evaluating dysfunction of the eustachian tube.

  18. Hacking the Matrix.

    PubMed

    Czerwinski, Michael; Spence, Jason R

    2017-01-05

    Recently in Nature, Gjorevski et al. (2016) describe a fully defined synthetic hydrogel that mimics the extracellular matrix to support in vitro growth of intestinal stem cells and organoids. The hydrogel allows exquisite control over the chemical and physical in vitro niche and enables identification of regulatory properties of the matrix.

  19. Polymer NDE; Proceedings of the European Workshop on Nondestructive Evaluation of Polymers and Polymer Matrix Composites, Termar do Vimeiro, Portugal, September 4, 5, 1984

    SciTech Connect

    Ashbe, K.M.G.

    1986-01-01

    The state of the art in the characterization, detection and quantification of defects in polymer materials for industrial and aerospace applications is described. The defects include inhomogeneous mixing, inclusions of foreign materials, macroscopic anisotropy, segregation and residual stress. The manifestations of the defects are discussed in terms of NDT methods for probing the microstructure at the molecular level and for determining the molecular orientation of the polymer constituents. NDT techniques are also described for lifetime prediction and in-service testing of laminated composites. Analytical methods are reviewed for using acoustic emission data to monitor physical changes in gels and solids, detect defects in filament wound pressure vessels, and evaluate failure mechanisms in CFRP materials. NDT applications are also described for employing electromagnetic wave propagation, vibrations, elastic wave, and holographic interferographic data for qualitative and quantitative evaluation of the effects of defects and loading on polymer materials.

  20. Revisiting Lepton Flavor Universality in B Decays.

    PubMed

    Feruglio, Ferruccio; Paradisi, Paride; Pattori, Andrea

    2017-01-06

    Lepton flavor universality (LFU) in B decays is revisited by considering a class of semileptonic operators defined at a scale Λ above the electroweak scale v. The importance of quantum effects, so far neglected in the literature, is emphasized. We construct the low-energy effective Lagrangian taking into account the running effects from Λ down to v through the one-loop renormalization group equations (RGEs) in the limit of exact electroweak symmetry and QED RGEs from v down to the 1 GeV scale. The most important quantum effects turn out to be the modification of the leptonic couplings of the vector boson Z and the generation of a purely leptonic effective Lagrangian. Large LFU breaking effects in Z and τ decays and visible lepton flavor violating effects in the processes τ→μℓℓ, τ→μρ, τ→μπ, and τ→μη^{(')} are induced.

  1. Revisiting Lepton Flavor Universality in B Decays

    NASA Astrophysics Data System (ADS)

    Feruglio, Ferruccio; Paradisi, Paride; Pattori, Andrea

    2017-01-01

    Lepton flavor universality (LFU) in B decays is revisited by considering a class of semileptonic operators defined at a scale Λ above the electroweak scale v . The importance of quantum effects, so far neglected in the literature, is emphasized. We construct the low-energy effective Lagrangian taking into account the running effects from Λ down to v through the one-loop renormalization group equations (RGEs) in the limit of exact electroweak symmetry and QED RGEs from v down to the 1 GeV scale. The most important quantum effects turn out to be the modification of the leptonic couplings of the vector boson Z and the generation of a purely leptonic effective Lagrangian. Large LFU breaking effects in Z and τ decays and visible lepton flavor violating effects in the processes τ →μ ℓℓ, τ →μ ρ , τ →μ π , and τ →μ η(') are induced.

  2. Re-visiting the electrophysiology of language.

    PubMed

    Obleser, Jonas

    2015-09-01

    This editorial accompanies a special issue of Brain and Language re-visiting old themes and new leads in the electrophysiology of language. The event-related potential (ERP) as a series of characteristic deflections ("components") over time and their distribution on the scalp has been exploited by speech and language researchers over decades to find support for diverse psycholinguistic models. Fortunately, methodological and statistical advances have allowed human neuroscience to move beyond some of the limitations imposed when looking at the ERP only. Most importantly, we currently witness a refined and refreshed look at "event-related" (in the literal sense) brain activity that relates itself more closely to the actual neurobiology of speech and language processes. It is this imminent change in handling and interpreting electrophysiological data of speech and language experiments that this special issue intends to capture.

  3. Revisiting gravitino dark matter in thermal leptogenesis

    NASA Astrophysics Data System (ADS)

    Ibe, Masahiro; Suzuki, Motoo; Yanagida, Tsutomu T.

    2017-02-01

    In this paper, we revisit the gravitino dark matter scenario in the presence of the bilinear R-parity violating interaction. In particular, we discuss a consistency with the thermal leptogenesis. For a high reheating temperature required for the thermal leptogenesis, the gravitino dark matter tends to be overproduced, which puts a severe upper limit on the gluino mass. As we will show, a large portion of parameter space of the gravitino dark matter scenario has been excluded by combining the constraints from the gravitino abundance and the null results of the searches for the superparticles at the LHC experiments. In particular, the models with the stau (and other charged slepton) NLSP has been almost excluded by the searches for the long-lived charged particles at the LHC unless the required reheating temperature is somewhat lowered by assuming, for example, a degenerated right-handed neutrino mass spectrum.

  4. Olfactory pathogenesis of idiopathic Parkinson disease revisited.

    PubMed

    Lerner, Alicja; Bagic, Anto

    2008-06-15

    Idiopathic Parkinson disease (PD) is traditionally considered a movement disorder with hallmark lesions located in the substantia nigra pars compacta (SNpc). However, recent histopathological studies of some PD cases suggest the possibility of a multisystem disorder which progresses in a predictable sequence as described in Braak's staging criteria. The disease process starts in the dorsal motor nucleus of the vagus (dmX) and anterior olfactory nucleus and bulb, and from there, spreads through the brainstem nuclei to ultimately reach the SNpc, which then presents as symptomatic PD. In this article, we would like to revisit the olfactory pathogenesis of PD based on Braak's staging system and review anatomical pathways supporting such a possibility. We also suggest some biomarkers for early stages of PD. Additionally, we present and discuss the possibility that a prion-like process underlies the neurodegenerative changes in PD.

  5. Seasonal dating of Sappho's 'Midnight Poem' revisited

    NASA Astrophysics Data System (ADS)

    Cuntz, Manfred; Gurdemir, Levent; George, Martin

    2016-04-01

    Sappho was a Greek lyric poet who composed a significant array of pristine poetry. Although much of it has been lost, her reputation has endured thanks to numerous surviving fragments. One of her contributions includes the so-called 'Midnight Poem', which contains a line about the Pleiades, setting sometime before midnight, and supposedly observed from the island of Lesbos. This poem also refers to the setting of the Moon. Sappho's Midnight Poem thus represents a prime example of where ancient poetry and astronomy merge, and it also offers the possibility of seasonal dating. Previously, Herschberg and Mebius (1990) estimated that the poem was composed in late winter/early spring, a time frame that is not unusual for lyrics of an amorous nature. The aim of our paper is to revisit this earlier finding by using modern-day software. Our study confirms Herschberg and Mebius' result, but also conveys further information.

  6. Visser's massive graviton bimetric theory revisited

    SciTech Connect

    Roany, Alain de; Chauvineau, Bertrand; Freitas Pacheco, Jose A. de

    2011-10-15

    A massive gravity theory was proposed by Visser in the late 1990s. This theory, based on a background metric b{sub {alpha}{beta}} and on an usual dynamical metric g{sub {alpha}{beta}} has the advantage of being free of ghosts as well as discontinuities present in other massive theories proposed in the past. In the present investigation, the equations of Visser's theory are revisited with particular care on the related conservation laws. It will be shown that a multiplicative factor is missing in the graviton tensor originally derived by Visser, which has no incidence on the weak field approach but becomes important in the strong field regime when, for instance, cosmological applications are considered. In this case, contrary to some previous claims found in the literature, we conclude that a nonstatic background metric is required in order to obtain a solution able to mimic the {Lambda}CDM cosmology.

  7. Revisiting the R νMDM models

    NASA Astrophysics Data System (ADS)

    Cai, Yi; Schmidt, Michael A.

    2016-05-01

    Combining neutrino mass generation and a dark matter candidate in a unified model has always been intriguing. We revisit the class of R νMDM models, which incorporate minimal dark matter in radiative neutrino mass models based on the one-loop ultraviolet completions of the Weinberg operator. The possibility of an exact accidental Z 2 is completely ruled out in this scenario. We study the phenomenology of one of the models with an approximate Z 2 symmetry. In addition to the Standard Model particles, it contains two real scalar quintuplets, one vector-like quadruplet fermion and a fermionic quintuplet. The neutral component of the fermionic quintuplet serves as a good dark matter candidate which can be tested by the future direct and indirect detection experiments. The constraints from flavor physics and electroweak-scale naturalness are also discussed.

  8. Grassmann matrix quantum mechanics

    DOE PAGES

    Anninos, Dionysios; Denef, Frederik; Monten, Ruben

    2016-04-21

    We explore quantum mechanical theories whose fundamental degrees of freedom are rectangular matrices with Grassmann valued matrix elements. We study particular models where the low energy sector can be described in terms of a bosonic Hermitian matrix quantum mechanics. We describe the classical curved phase space that emerges in the low energy sector. The phase space lives on a compact Kähler manifold parameterized by a complex matrix, of the type discovered some time ago by Berezin. The emergence of a semiclassical bosonic matrix quantum mechanics at low energies requires that the original Grassmann matrices be in the long rectangular limit.more » In conclusion, we discuss possible holographic interpretations of such matrix models which, by construction, are endowed with a finite dimensional Hilbert space.« less

  9. Grassmann matrix quantum mechanics

    SciTech Connect

    Anninos, Dionysios; Denef, Frederik; Monten, Ruben

    2016-04-21

    We explore quantum mechanical theories whose fundamental degrees of freedom are rectangular matrices with Grassmann valued matrix elements. We study particular models where the low energy sector can be described in terms of a bosonic Hermitian matrix quantum mechanics. We describe the classical curved phase space that emerges in the low energy sector. The phase space lives on a compact Kähler manifold parameterized by a complex matrix, of the type discovered some time ago by Berezin. The emergence of a semiclassical bosonic matrix quantum mechanics at low energies requires that the original Grassmann matrices be in the long rectangular limit. In conclusion, we discuss possible holographic interpretations of such matrix models which, by construction, are endowed with a finite dimensional Hilbert space.

  10. Fuzzy risk matrix.

    PubMed

    Markowski, Adam S; Mannan, M Sam

    2008-11-15

    A risk matrix is a mechanism to characterize and rank process risks that are typically identified through one or more multifunctional reviews (e.g., process hazard analysis, audits, or incident investigation). This paper describes a procedure for developing a fuzzy risk matrix that may be used for emerging fuzzy logic applications in different safety analyses (e.g., LOPA). The fuzzification of frequency and severity of the consequences of the incident scenario are described which are basic inputs for fuzzy risk matrix. Subsequently using different design of risk matrix, fuzzy rules are established enabling the development of fuzzy risk matrices. Three types of fuzzy risk matrix have been developed (low-cost, standard, and high-cost), and using a distillation column case study, the effect of the design on final defuzzified risk index is demonstrated.

  11. A matrix model from string field theory

    NASA Astrophysics Data System (ADS)

    Zeze, Syoji

    2016-09-01

    We demonstrate that a Hermitian matrix model can be derived from level truncated open string field theory with Chan-Paton factors. The Hermitian matrix is coupled with a scalar and U(N) vectors which are responsible for the D-brane at the tachyon vacuum. Effective potential for the scalar is evaluated both for finite and large N. Increase of potential height is observed in both cases. The large N matrix integral is identified with a system of N ZZ branes and a ghost FZZT brane.

  12. Matrix computations on mesh arrays

    SciTech Connect

    Moreno, J.H.

    1989-01-01

    This dissertation addresses the systematic derivation of mesh arrays for matrix computations, in particular realizing the algorithm-specific arrays and mapping algorithms onto class-specific arrays. A data-dependency graph-based transformational method is proposed in a design frame work consisting of two stages, namely algorithm regularization and derivation of arrays. The first stage derives the fully-parallel data-dependency graph (FPG) of an algorithm and transforms this graph into a three-dimensional one with unidirectional nearest-neighbor dependencies (a multi-mesh graph MMG). The second stage transforms the MMG into a two-dimensional G-graph, which is realized as an algorithm-specific array or mapped onto a class-specific array. This stage allows the incorporation of implementation restrictions and the evaluation of tradeoffs in properties of cells, as well as the derivation of arrays for fixed-size data and partitioned problems, while performing optimization of specific performance/cost measures. The proposed method is formalized by presenting a sufficient set of transformations and demonstrating the equivalence of graphs obtained from those transformations. Moreover, it is demonstrated that the MMG representation is always possible, due to the characteristics of the operators. The method has been applied to a collection of matrix algorithms, including matrix multiplication, convolution, matrix decompositions, transitive closure, the Faddeev algorithm, and BBA{sup {minus}1}. The examples show that, in addition to the features listed earlier, this method is easy to apply. Moreover, the method is compared with other techniques, concluding that it is advantageous because it meets evaluation criteria and produces more efficient arrays.

  13. Hybrid matrix amplifier

    DOEpatents

    Martens, J.S.; Hietala, V.M.; Plut, T.A.

    1995-01-03

    The present invention comprises a novel matrix amplifier. The matrix amplifier includes an active superconducting power divider (ASPD) having N output ports; N distributed amplifiers each operatively connected to one of the N output ports of the ASPD; and a power combiner having N input ports each operatively connected to one of the N distributed amplifiers. The distributed amplifier can included M stages of amplification by cascading superconducting active devices. The power combiner can include N active elements. The resulting (N[times]M) matrix amplifier can produce signals of high output power, large bandwidth, and low noise. 6 figures.

  14. Hybrid matrix amplifier

    DOEpatents

    Martens, Jon S.; Hietala, Vincent M.; Plut, Thomas A.

    1995-01-01

    The present invention comprises a novel matrix amplifier. The matrix amplifier includes an active superconducting power divider (ASPD) having N output ports; N distributed amplifiers each operatively connected to one of the N output ports of the ASPD; and a power combiner having N input ports each operatively connected to one of the N distributed amplifiers. The distributed amplifier can included M stages of amplification by cascading superconducting active devices. The power combiner can include N active elements. The resulting (N.times.M) matrix amplifier can produce signals of high output power, large bandwidth, and low noise.

  15. Faces of matrix models

    NASA Astrophysics Data System (ADS)

    Morozov, A.

    2012-08-01

    Partition functions of eigenvalue matrix models possess a number of very different descriptions: as matrix integrals, as solutions to linear and nonlinear equations, as τ-functions of integrable hierarchies and as special-geometry prepotentials, as result of the action of W-operators and of various recursions on elementary input data, as gluing of certain elementary building blocks. All this explains the central role of such matrix models in modern mathematical physics: they provide the basic "special functions" to express the answers and relations between them, and they serve as a dream model of what one should try to achieve in any other field.

  16. Pesticide-Exposure Matrix

    Cancer.gov

    The "Pesticide-exposure Matrix" was developed to help epidemiologists and other researchers identify the active ingredients to which people were likely exposed when their homes and gardens were treated for pests in past years.

  17. Floating matrix dosage form for dextromethorphan hydrobromide based on gas forming technique: in vitro and in vivo evaluation in healthy volunteers.

    PubMed

    Hu, Liandong; Li, Li; Yang, Xun; Liu, Wei; Yang, Jianxue; Jia, Yanhong; Shang, Chuang; Xu, Hongxin

    2011-01-18

    The objective of this study was to develop the dextromethorphan hydrobromide sustained-release (DMB-SR) tablets using floating technique to prolong the gastric residence time and compared their pharmacokinetic behavior with conventional sustained release tablets. DMB-SR floating tablets were prepared employing hydroxypropyl methylcellulose (HPMC) as hydrophilic gel material, sodium bicarbonate as gas-generating agent and hexadecanol as floating assistant agent. An orthogonal experiment design method was used to select the optimized formulation. The floating tablets were evaluated for uniformity of weight, hardness, friability, drug content, floating characteristics, in vitro release and in vivo bioavailability. The optimized tablets were prepared with HPMC K4M 25 mg, sodium bicarbonate 20 mg and hexadecanol 18 mg. The prepared tablets could float within 3 min and maintain for more than 24 h. The data of physical parameters were all lie within the limits. Drug release at 12 h was more than 85%. The comparative pharmacokinetic study was performed by administration of the DMB-SR floating tablets and conventional DMB-SR tablets. The area under curve of plasma concentration-time (AUC) of floating tablets was slightly higher than that of reference tablets, T(max) was prolonged apparently. The results showed the floating tablets are a feasible approach for the sustained-release preparation of drugs, which have limited absorption sites in the stomach.

  18. Evaluation of MALDI-TOF MS (Matrix-Assisted Laser Desorption-Ionization Time-of-Flight Mass Spectrometry) for routine identification of anaerobic bacteria.

    PubMed

    Rodríguez-Sánchez, Belén; Alcalá, Luis; Marín, Mercedes; Ruiz, Adrián; Alonso, Elena; Bouza, Emilio

    2016-12-01

    Information regarding the use of MALDI-TOF MS as an alternative to conventional laboratory methods for the rapid and reliable identification of bacterial isolates is still limited. In this study, MALDI-TOF MS was evaluated on 295 anaerobic isolates previously identified by 16S rRNA gene sequencing and with biochemical tests (Rapid ID 32A system, BioMérieux). In total, 85.8% of the isolates were identified by MALDI-TOF MS at the species level vs 49.8% using the Rapid ID 32A system (p < 0.0001). None of the isolates was discordantly identified at the genus level using MALDI-TOF MS and only 9 of them could not be identified using the method. Thus, our results show that MALDI-TOF MS is a robust and reliable tool for the identification of anaerobic isolates in the microbiology laboratory. Its implementation will reduce the turnaround time for a final identification and the number of isolates that require 16S rRNA sequencing.

  19. Nonadiabatic couplings from the Kohn-Sham derivative matrix: Formulation by time-dependent density-functional theory and evaluation in the pseudopotential framework

    NASA Astrophysics Data System (ADS)

    Hu, Chunping; Sugino, Osamu; Hirai, Hirotoshi; Tateyama, Yoshitaka

    2010-12-01

    We study the time-dependent density-functional theory formulation of nonadiabatic couplings (NAC’s) to settle problems regarding practical calculations. NAC’s have so far been rigorously formulated on the basis of the density response scheme and expressed using the nuclear derivative of the Hamiltonian, ∂H/∂R, whereby causing the pseudopotential problem. When rewritten using the nuclear derivative operator, ∂/∂R, or the d operator, the formula is found free of the problem and thus provides a working numerical scheme. The d-operator-based formulation also allows us to lay a foundation on the empirical Slater transition-state method and to show an improved way of using the auxiliary excited-state wave-function ansatz, both of which have been utilized in previous works. Evaluation of NAC near either the Jahn-Teller or the Renner-Teller intersection in various molecular systems shows that the values of NAC are much improved over previous calculations when the d-operator formula is implemented in the pseudopotential framework.

  20. Functional Polymer Matrix Fibers

    DTIC Science & Technology

    2007-11-02

    the carbon nanofibers led to the deterioration of the polymeric cellulose structure. Extensive research on the surface treatment of carbon nanofibers...1 November 2003 - 14-Mar-05 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER FA8655-03-1-3042 Functional Polymer Matrix Fibres 5b. GRANT NUMBER 5c. PROGRAM...MARYLABONE RD LONDON NWl 5TH PERFORMANCE REPORT Project title: Functional polymer matrix fibers Period of performance: 1 November 2003 - 31 October 2004

  1. Optical coherency matrix tomography

    PubMed Central

    Kagalwala, Kumel H.; Kondakci, H. Esat; Abouraddy, Ayman F.; Saleh, Bahaa E. A.

    2015-01-01

    The coherence of an optical beam having multiple degrees of freedom (DoFs) is described by a coherency matrix G spanning these DoFs. This optical coherency matrix has not been measured in its entirety to date—even in the simplest case of two binary DoFs where G is a 4 × 4 matrix. We establish a methodical yet versatile approach—optical coherency matrix tomography—for reconstructing G that exploits the analogy between this problem in classical optics and that of tomographically reconstructing the density matrix associated with multipartite quantum states in quantum information science. Here G is reconstructed from a minimal set of linearly independent measurements, each a cascade of projective measurements for each DoF. We report the first experimental measurements of the 4 × 4 coherency matrix G associated with an electromagnetic beam in which polarization and a spatial DoF are relevant, ranging from the traditional two-point Young’s double slit to spatial parity and orbital angular momentum modes. PMID:26478452

  2. Evaluation of anorganic bovine-derived hydroxyapatite matrix/cell binding peptide as a bone graft material in the treatment of human periodontal infrabony defects: A clinico-radiographic study

    PubMed Central

    Fatima, Ghousia; Shivamurthy, Ravindra; Thakur, Srinath; Baseer, Mohammad Abdul

    2015-01-01

    Background: Various bone graft materials have been used in the treatment of periodontal defects. A synthetic bone substitute material composed of P-15 with anorganic bone mineral has been scantly studied. Hence, the present study was aimed to evaluate and compare the efficacy of anorganic bovine-derived hydroxyapatite matrix (ABM)/cell binding peptide (P-15) in human periodontal infrabony defects with that of open flap debridement (OFD) alone. Materials and Methods: A split-mouth, randomized controlled clinical study was designed to investigate the efficacy of ABM/P-15. In this clinical trial, 10 patients having bilateral periodontal infrabony defects were treated either with ABM/P-15 or OFD and followed for a period of 9 months. At baseline and at 9 months probing pocket depth (PPD), relative attachment level (RAL), depth of a defect, and radiographic bone level were measured; and compared between test and control sites. Results: A statistically significant reduction (P < 0.001) in PPD was observed in test sites compared to control sites. Both sites showed a gain in RAL without any significant difference. Similarly, the radiographic evaluation revealed significantly higher radiographic defect fill in test sites as compared to control sites (P < 0.001). Conclusion: ABM/P-15 bone graft material appears to be useful and beneficial in the treatment of human periodontal infrabony defects. PMID:26941516

  3. Evaluation.

    ERIC Educational Resources Information Center

    McAnany, Emile G.; And Others

    1980-01-01

    Two lead articles set the theme for this issue devoted to evaluation as Emile G. McAnany examines the usefulness of evaluation and Robert C. Hornik addresses four widely accepted myths about evaluation. Additional articles include a report of a field evaluation done by the Accion Cultural Popular (ACPO); a study of the impact of that evaluation by…

  4. Decellularized bone matrix grafts for calvaria regeneration

    PubMed Central

    Lee, Dong Joon; Diachina, Shannon; Lee, Yan Ting; Zhao, Lixing; Zou, Rui; Tang, Na; Han, Han; Chen, Xin; Ko, Ching-Chang

    2016-01-01

    Decellularization is a promising new method to prepare natural matrices for tissue regeneration. Successful decellularization has been reported using various tissues including skin, tendon, and cartilage, though studies using hard tissue such as bone are lacking. In this study, we aimed to define the optimal experimental parameters to decellularize natural bone matrix using 0.5% sodium dodecyl sulfate and 0.1% NH4OH. Then, the effects of decellularized bone matrix on rat mesenchymal stem cell proliferation, osteogenic gene expression, and osteogenic differentiations in a two-dimensional culture system were investigated. Decellularized bone was also evaluated with regard to cytotoxicity, biochemical, and mechanical characteristics in vitro. Evidence of complete decellularization was shown through hematoxylin and eosin staining and DNA measurements. Decellularized bone matrix displayed a cytocompatible property, conserved structure, mechanical strength, and mineral content comparable to natural bone. To study new bone formation, implantation of decellularized bone matrix particles seeded with rat mesenchymal stem cells was conducted using an orthotopic in vivo model. After 3 months post-implantation into a critical-sized defect in rat calvaria, new bone was formed around decellularized bone matrix particles and also merged with new bone between decellularized bone matrix particles. New bone formation was analyzed with micro computed tomography, mineral apposition rate, and histomorphometry. Decellularized bone matrix stimulated mesenchymal stem cell proliferation and osteogenic differentiation in vitro and in vivo, achieving effective bone regeneration and thereby serving as a promising biological bone graft. PMID:28228929

  5. Predator-prey interactions, resource depression and patch revisitation

    USGS Publications Warehouse

    Erwin, R.M.

    1989-01-01

    Generalist predators may be confronted by different types of prey in different patches: sedentary and conspicuous, cryptic (with or without refugia), conspicuous and nonsocial, or conspicuous and social. I argue that, where encounter rates with prey are of most importance, patch revisitation should be a profitable tactic where prey have short 'recovery' times (conspicuous, nonsocial prey), or where anti-predator response (e.g. shoaling) may increase conspicuousness. Predictions are made for how temporal changes in prey encounter rates should affect revisit schedules and feeding rates for the 4 different prey types.

  6. Revisiting the phase diagram of hard ellipsoids

    NASA Astrophysics Data System (ADS)

    Odriozola, Gerardo

    2012-04-01

    In this work, the well-known Frenkel-Mulder phase diagram of hard ellipsoids of revolution [D. Frenkel and B. M. Mulder, Mol. Phys. 55, 1171 (1985), 10.1080/00268978500101971] is revisited by means of replica exchange Monte Carlo simulations. The method provides good sampling of dense systems and so, solid phases can be accessed without the need of imposing a given structure. At high densities, we found plastic solids and fcc-like crystals for semi-spherical ellipsoids (prolates and oblates), and SM2 structures [P. Pfleiderer and T. Schilling, Phys. Rev. E 75, 020402 (2007)] for x : 1-prolates and 1 : x-oblates with x ≥ 3. The revised fluid-crystal and isotropic-nematic transitions reasonably agree with those presented in the Frenkel-Mulder diagram. An interesting result is that, for small system sizes (100 particles), we obtained 2:1- and 1.5:1-prolate equations of state without transitions, while some order is developed at large densities. Furthermore, the symmetric oblate cases are also reluctant to form ordered phases.

  7. Targeting Cancer Metabolism - Revisiting the Warburg Effects

    PubMed Central

    Tran, Quangdon; Lee, Hyunji; Park, Jisoo; Kim, Seon-Hwan; Park, Jongsun

    2016-01-01

    After more than half of century since the Warburg effect was described, this atypical metabolism has been standing true for almost every type of cancer, exhibiting higher glycolysis and lactate metabolism and defective mitochondrial ATP production. This phenomenon had attracted many scientists to the problem of elucidating the mechanism of, and reason for, this effect. Several models based on oncogenic studies have been proposed, such as the accumulation of mitochondrial gene mutations, the switch from oxidative phosphorylation respiration to glycolysis, the enhancement of lactate metabolism, and the alteration of glycolytic genes. Whether the Warburg phenomenon is the consequence of genetic dysregulation in cancer or the cause of cancer remains unknown. Moreover, the exact reasons and physiological values of this peculiar metabolism in cancer remain unclear. Although there are some pharmacological compounds, such as 2-deoxy-D-glucose, dichloroacetic acid, and 3-bromopyruvate, therapeutic strategies, including diet, have been developed based on targeting the Warburg effect. In this review, we will revisit the Warburg effect to determine how much scientists currently understand about this phenomenon and how we can treat the cancer based on targeting metabolism. PMID:27437085

  8. Revisiting the argument from fetal potential.

    PubMed

    Manninen, Bertha Alvarez

    2007-05-17

    One of the most famous, and most derided, arguments against the morality of abortion is the argument from potential, which maintains that the fetus' potential to become a person and enjoy the valuable life common to persons, entails that its destruction is prima facie morally impermissible. In this paper, I will revisit and offer a defense of the argument from potential.First, I will criticize the classical arguments proffered against the importance of fetal potential, specifically the arguments put forth by philosophers Peter Singer and David Boonin, by carefully unpacking the claims made in these arguments and illustrating why they are flawed.Secondly, I will maintain that fetal potential is morally relevant when it comes to the morality of abortion, but that it must be accorded a proper place in the argument. This proper place, however, cannot be found until we first answer a very important and complex question: we must first address the issue of personal identity, and when the fetus becomes the type of being who is relevantly identical to a future person. I will illustrate why the question of fetal potential can only be meaningfully addressed after we have first answered the question of personal identity and how it relates to the human fetus.

  9. Carbon emission from global hydroelectric reservoirs revisited.

    PubMed

    Li, Siyue; Zhang, Quanfa

    2014-12-01

    Substantial greenhouse gas (GHG) emissions from hydropower reservoirs have been of great concerns recently, yet the significant carbon emitters of drawdown area and reservoir downstream (including spillways and turbines as well as river reaches below dams) have not been included in global carbon budget. Here, we revisit GHG emission from hydropower reservoirs by considering reservoir surface area, drawdown zone and reservoir downstream. Our estimates demonstrate around 301.3 Tg carbon dioxide (CO2)/year and 18.7 Tg methane (CH4)/year from global hydroelectric reservoirs, which are much higher than recent observations. The sum of drawdown and downstream emission, which is generally overlooked, represents 42 % CO2 and 67 % CH4 of the total emissions from hydropower reservoirs. Accordingly, the global average emissions from hydropower are estimated to be 92 g CO2/kWh and 5.7 g CH4/kWh. Nonetheless, global hydroelectricity could currently reduce approximate 2,351 Tg CO2eq/year with respect to fuel fossil plant alternative. The new findings show a substantial revision of carbon emission from the global hydropower reservoirs.

  10. Hyperinflation in Brazil, Israel, and Nicaragua revisited

    NASA Astrophysics Data System (ADS)

    Szybisz, Martín A.; Szybisz, Leszek

    2017-01-01

    The aim of the present work is to address the description of hyperinflation regimens in economy. The spirals of hyperinflation developed in Brazil, Israel, and Nicaragua are revisited. This new analysis of data indicates that the episodes occurred in Brazil and Nicaragua can be understood within the frame of the model available in the literature, which is based on a nonlinear feedback (NLF) characterized by an exponent β > 0. In the NLF model the accumulated consumer price index carries a finite time singularity of the type 1 /(tc - t) (1 - β) / β determining a critical time tc at which the economy would crash. It is shown that in the case of Brazil the entire episode cannot be described with a unique set of parameters because the time series was strongly affected by a change of policy. This fact gives support to the "so called" Lucas critique, who stated that model's parameters usually change once policy changes. On the other hand, such a model is not able to provide any tc in the case of the weaker hyperinflation occurred in Israel. It is shown that in this case the fit of data yields β → 0. This limit leads to the linear feedback formulation which does not predict any tc. An extension for the NLF model is suggested.

  11. [What mirror neurons have revealed: revisited].

    PubMed

    Murata, Akira; Maeda, Kazutaka

    2014-06-01

    The first paper on mirror neurons was published in 1992. In the span of over two decades since then, much knowledge about the relationship between social cognitive function and the motor control system has been accumulated. Direct matching of visual actions and their corresponding motor representations is the most important functional property of mirror neuron. Many studies have emphasized intrinsic simulation as a core concept for mirror neurons. Mirror neurons are thought to play a role in social cognitive function. However, the function of mirror neurons in the macaque remains unclear, because such cognitive functions are limited or lacking in macaque monkeys. It is therefore important to discuss these neurons in the context of motor function. Rizzolatti and colleagues have stressed that the most important function of mirror neurons in macaques is recognition of actions performed by other individuals. I suggest that mirror neurons in the Macaque inferior pariental lobule might be correlated with body schema. In the parieto-premotor network, matching of corollary discharge and actual sensory feedback is an essential neuronal operation. Recently, neurons showing mirror properties were found in some cortical areas outside the mirror neuron system. The current work would revisit the outcomes of mirror neuron studies to discuss the function of mirror neurons in the monkey.

  12. No-scale ripple inflation revisited

    SciTech Connect

    Li, Tianjun; Li, Zhijin; Nanopoulos, Dimitri V. E-mail: lizhijin@physics.tamu.edu

    2014-04-01

    We revisit the no-scale ripple inflation model, where no-scale supergravity is modified by an additional term for the inflaton field in the Kähler potential. This term not only breaks one SU(N,1) symmetry explicitly, but also plays an important role for inflation. We generalize the superpotential in the no-scale ripple inflation model slightly. There exists a discrete Z{sub 2} symmetry/parity in the scalar potential in general, which can be preserved or violated by the non-canonical nomalized inflaton kinetic term. Thus, there are three inflation paths: one parity invariant path, and the left and right paths for parity violating scenario. We show that the inflations along the parity invariant path and right path are consistent with the Planck results. However, the gavitino mass for the parity invariant path is so large that the inflation results will be invalid if we consider the inflaton supersymmetry breaking soft mass term. Thus, only the inflation along the right path gives the correct and consistent results. Notably, the tensor-to-scalar ratio in such case can be large, with a value around 0.05, which may be probed by the future Planck experiment.

  13. The super-GUT CMSSM revisited

    NASA Astrophysics Data System (ADS)

    Ellis, John; Evans, Jason L.; Mustafayev, Azar; Nagata, Natsumi; Olive, Keith A.

    2016-11-01

    We revisit minimal supersymmetric SU(5) grand unification (GUT) models in which the soft supersymmetry-breaking parameters of the minimal supersymmetric Standard Model (MSSM) are universal at some input scale, M_in, above the supersymmetric gauge-coupling unification scale, M_GUT. As in the constrained MSSM (CMSSM), we assume that the scalar masses and gaugino masses have common values, m_0 and m_{1/2}, respectively, at M_in, as do the trilinear soft supersymmetry-breaking parameters A_0. Going beyond previous studies of such a super-GUT CMSSM scenario, we explore the constraints imposed by the lower limit on the proton lifetime and the LHC measurement of the Higgs mass, m_h. We find regions of m_0, m_{1/2}, A_0 and the parameters of the SU(5) superpotential that are compatible with these and other phenomenological constraints such as the density of cold dark matter, which we assume to be provided by the lightest neutralino. Typically, these allowed regions appear for m_0 and m_{1/2} in the multi-TeV region, for suitable values of the unknown SU(5) GUT-scale phases and superpotential couplings, and with the ratio of supersymmetric Higgs vacuum expectation values tan β ≲ 6.

  14. Post-inflationary gravitino production revisited

    SciTech Connect

    Ellis, John; Garcia, Marcos A.G.; Olive, Keith A.; Nanopoulos, Dimitri V.; Peloso, Marco E-mail: garciagarcia@physics.umn.edu E-mail: olive@physics.umn.edu

    2016-03-01

    We revisit gravitino production following inflation. As a first step, we review the standard calculation of gravitino production in the thermal plasma formed at the end of post-inflationary reheating when the inflaton has completely decayed. Next we consider gravitino production prior to the completion of reheating, assuming that the inflaton decay products thermalize instantaneously while they are still dilute. We then argue that instantaneous thermalization is in general a good approximation, and also show that the contribution of non-thermal gravitino production via the collisions of inflaton decay products prior to thermalization is relatively small. Our final estimate of the gravitino-to-entropy ratio is approximated well by a standard calculation of gravitino production in the post-inflationary thermal plasma assuming total instantaneous decay and thermalization at a time t ≅ 1.2/Γ{sub φ}. Finally, in light of our calculations, we consider potential implications of upper limits on the gravitino abundance for models of inflation, with particular attention to scenarios for inflaton decays in supersymmetric Starobinsky-like models.

  15. Revisiting the phase diagram of hard ellipsoids.

    PubMed

    Odriozola, Gerardo

    2012-04-07

    In this work, the well-known Frenkel-Mulder phase diagram of hard ellipsoids of revolution [D. Frenkel and B. M. Mulder, Mol. Phys. 55, 1171 (1985)] is revisited by means of replica exchange Monte Carlo simulations. The method provides good sampling of dense systems and so, solid phases can be accessed without the need of imposing a given structure. At high densities, we found plastic solids and fcc-like crystals for semi-spherical ellipsoids (prolates and oblates), and SM2 structures [P. Pfleiderer and T. Schilling, Phys. Rev. E 75, 020402 (2007)] for x : 1-prolates and 1 : x-oblates with x ≥ 3. The revised fluid-crystal and isotropic-nematic transitions reasonably agree with those presented in the Frenkel-Mulder diagram. An interesting result is that, for small system sizes (100 particles), we obtained 2:1- and 1.5:1-prolate equations of state without transitions, while some order is developed at large densities. Furthermore, the symmetric oblate cases are also reluctant to form ordered phases.

  16. Binocularity and visual search-Revisited.

    PubMed

    Zou, Bochao; Utochkin, Igor S; Liu, Yue; Wolfe, Jeremy M

    2017-02-01

    Binocular rivalry is a phenomenon of visual competition in which perception alternates between two monocular images. When two eye's images only differ in luminance, observers may perceive shininess, a form of rivalry called binocular luster. Does dichoptic information guide attention in visual search? Wolfe and Franzel (Perception & Psychophysics, 44(1), 81-93, 1988) reported that rivalry could guide attention only weakly, but that luster (shininess) "popped out," producing very shallow Reaction Time (RT) × Set Size functions. In this study, we have revisited the topic with new and improved stimuli. By using a checkerboard pattern in rivalry experiments, we found that search for rivalry can be more efficient (16 ms/item) than standard, rivalrous grating (30 ms/item). The checkerboard may reduce distracting orientation signals that masked the salience of rivalry between simple orthogonal gratings. Lustrous stimuli did not pop out when potential contrast and luminance artifacts were reduced. However, search efficiency was substantially improved when luster was added to the search target. Both rivalry and luster tasks can produce search asymmetries, as is characteristic of guiding features in search. These results suggest that interocular differences that produce rivalry or luster can guide attention, but these effects are relatively weak and can be hidden by other features like luminance and orientation in visual search tasks.

  17. Generalized matrix inversion is not harder than matrix multiplication

    NASA Astrophysics Data System (ADS)

    Petkovic, Marko D.; Stanimirovic, Predrag S.

    2009-08-01

    Starting from the Strassen method for rapid matrix multiplication and inversion as well as from the recursive Cholesky factorization algorithm, we introduced a completely block recursive algorithm for generalized Cholesky factorization of a given symmetric, positive semi-definite matrix . We used the Strassen method for matrix inversion together with the recursive generalized Cholesky factorization method, and established an algorithm for computing generalized {2,3} and {2,4} inverses. Introduced algorithms are not harder than the matrix-matrix multiplication.

  18. Extracellular matrix structure.

    PubMed

    Theocharis, Achilleas D; Skandalis, Spyros S; Gialeli, Chrysostomi; Karamanos, Nikos K

    2016-02-01

    Extracellular matrix (ECM) is a non-cellular three-dimensional macromolecular network composed of collagens, proteoglycans/glycosaminoglycans, elastin, fibronectin, laminins, and several other glycoproteins. Matrix components bind each other as well as cell adhesion receptors forming a complex network into which cells reside in all tissues and organs. Cell surface receptors transduce signals into cells from ECM, which regulate diverse cellular functions, such as survival, growth, migration, and differentiation, and are vital for maintaining normal homeostasis. ECM is a highly dynamic structural network that continuously undergoes remodeling mediated by several matrix-degrading enzymes during normal and pathological conditions. Deregulation of ECM composition and structure is associated with the development and progression of several pathologic conditions. This article emphasizes in the complex ECM structure as to provide a better understanding of its dynamic structural and functional multipotency. Where relevant, the implication of the various families of ECM macromolecules in health and disease is also presented.

  19. Matrix interdiction problem

    SciTech Connect

    Pan, Feng; Kasiviswanathan, Shiva

    2010-01-01

    In the matrix interdiction problem, a real-valued matrix and an integer k is given. The objective is to remove k columns such that the sum over all rows of the maximum entry in each row is minimized. This combinatorial problem is closely related to bipartite network interdiction problem which can be applied to prioritize the border checkpoints in order to minimize the probability that an adversary can successfully cross the border. After introducing the matrix interdiction problem, we will prove the problem is NP-hard, and even NP-hard to approximate with an additive n{gamma} factor for a fixed constant {gamma}. We also present an algorithm for this problem that achieves a factor of (n-k) mUltiplicative approximation ratio.

  20. Evaluating Training.

    ERIC Educational Resources Information Center

    Brethower, Karen S.; Rummler, Geary A.

    1979-01-01

    Presents general systems models (ballistic system, guided system, and adaptive system) and an evaluation matrix to help in examining training evaluation alternatives and in deciding what evaluation is appropriate. Includes some guidelines for conducting evaluation studies using four designs (control group, reversal, multiple baseline, and…

  1. Matrixed business support comparison study.

    SciTech Connect

    Parsons, Josh D.

    2004-11-01

    The Matrixed Business Support Comparison Study reviewed the current matrixed Chief Financial Officer (CFO) division staff models at Sandia National Laboratories. There were two primary drivers of this analysis: (1) the increasing number of financial staff matrixed to mission customers and (2) the desire to further understand the matrix process and the opportunities and challenges it creates.

  2. Rheocasting Al Matrix Composites

    NASA Astrophysics Data System (ADS)

    Girot, F. A.; Albingre, L.; Quenisset, J. M.; Naslain, R.

    1987-11-01

    Aluminum alloy matrix composites reinforced by SiC short fibers (or whiskers) can be prepared by rheocasting, a process which consists of the incorporation and homogeneous distribution of the reinforcement by stirring within a semi-solid alloy. Using this technique, composites containing fiber volume fractions in the range of 8-15%, have been obtained for various fibers lengths (i.e., 1 mm, 3 mm and 6 mm for SiC fibers). This paper attempts to delineate the best compocasting conditions for aluminum matrix composites reinforced by short SiC (e.g Nicalon) or SiC whiskers (e.g., Tokamax) and characterize the resulting microstructures.

  3. Density matrix perturbation theory.

    PubMed

    Niklasson, Anders M N; Challacombe, Matt

    2004-05-14

    An orbital-free quantum perturbation theory is proposed. It gives the response of the density matrix upon variation of the Hamiltonian by quadratically convergent recursions based on perturbed projections. The technique allows treatment of embedded quantum subsystems with a computational cost scaling linearly with the size of the perturbed region, O(N(pert.)), and as O(1) with the total system size. The method allows efficient high order perturbation expansions, as demonstrated with an example involving a 10th order expansion. Density matrix analogs of Wigner's 2n+1 rule are also presented.

  4. Threshold Concepts and Student Engagement: Revisiting Pedagogical Content Knowledge

    ERIC Educational Resources Information Center

    Zepke, Nick

    2013-01-01

    This article revisits the notion that to facilitate quality learning requires teachers in higher education to have pedagogical content knowledge. It constructs pedagogical content knowledge as a teaching and learning space that brings content and pedagogy together. On the content knowledge side, it suggests that threshold concepts, akin to a…

  5. Magnetic Braking Revisited: Activities for the Undergraduate Laboratory

    ERIC Educational Resources Information Center

    Ireson, Gren; Twidle, John

    2008-01-01

    This paper revisits the demonstration of Lenz by dropping magnets down a non-magnetic tube. Recent publications are reviewed and ideas for undergraduate laboratory investigations are suggested. Finally, an example of matching theory to observation is presented. (Contains 4 tables, 5 figures and 3 footnotes.)

  6. Revisiting Jack Goody to Rethink Determinisms in Literacy Studies

    ERIC Educational Resources Information Center

    Collin, Ross

    2013-01-01

    This article revisits Goody's arguments about literacy's influence on social arrangements, culture, cognition, economics, and other domains of existence. Whereas some of his arguments tend toward technological determinism (i.e., literacy causes change in the world), other of his arguments construe literacy as a force that shapes and is shaped by…

  7. Revisiting the Role of Communication in Adolescent Intimate Partner Violence

    ERIC Educational Resources Information Center

    Messinger, Adam M.; Rickert, Vaughn I.; Fry, Deborah A.; Lessel, Harriet; Davidson, Leslie L.

    2012-01-01

    A growing literature suggests that communication strategies can promote or inhibit intimate partner violence (IPV). Research on communication is still needed on a group ripe for early IPV intervention: high school-aged adolescents. This article revisits our previous analyses of young female reproductive clinic patients (Messinger, Davidson, &…

  8. College-Level Sheltered Instruction: Revisiting the Issue of Effectiveness

    ERIC Educational Resources Information Center

    Knoblock, Natalia; Youngquist, Judy

    2016-01-01

    Finding an effective instruction mode for ESL students in the US educational system has not been an easy task. The country's secondary and tertiary institutions continue to struggle to meet the needs of their large non-native student populations. The article revisits the debate whether sheltered instruction is an effective model to follow. In our…

  9. Revisiting Constructivist Teaching Methods in Ontario Colleges Preparing for Accreditation

    ERIC Educational Resources Information Center

    Schultz, Rachel A.

    2015-01-01

    At the time of writing, the first community colleges in Ontario were preparing for transition to an accreditation model from an audit system. This paper revisits constructivist literature, arguing that a more pragmatic definition of constructivism effectively blends positivist and interactionist philosophies to achieve both student centred…

  10. Educational Administration and the Management of Knowledge: 1980 Revisited

    ERIC Educational Resources Information Center

    Bates, Richard

    2013-01-01

    This paper revisits the thesis of a 1980 paper that suggested a new approach to educational administration based upon the New Sociology of Education. In particular it updates answers to the six key questions asked by that paper: what counts as knowledge; how is what counts as knowledge organised; how is what counts as knowledge transmitted; how is…

  11. Closing Achievement Gaps: Revisiting Benjamin S. Bloom's "Learning for Mastery"

    ERIC Educational Resources Information Center

    Guskey, Thomas R.

    2007-01-01

    The problem of achievement gaps among different subgroups of students has been evident in education for many years. This manuscript revisits the work of renowned educator Benjamin S. Bloom, who saw reducing gaps in the achievement of various groups of students as a simple problem of reducing variation in student learning outcomes. Bloom observed…

  12. Moral Judgment Development across Cultures: Revisiting Kohlberg's Universality Claims

    ERIC Educational Resources Information Center

    Gibbs, John C.; Basinger, Karen S.; Grime, Rebecca L.; Snarey, John R.

    2007-01-01

    This article revisits Kohlberg's cognitive developmental claims that stages of moral judgment, facilitative processes of social perspective-taking, and moral values are commonly identifiable across cultures. Snarey [Snarey, J. (1985). "The cross-cultural universality of social-moral development: A critical review of Kohlbergian research."…

  13. Literary Origins of the Term "School Psychologist" Revisited

    ERIC Educational Resources Information Center

    Fagan, Thomas K.

    2005-01-01

    Previous research on the literary origins of the term "school psychologist" is revisited, and conclusions are revised in light of new evidence. It appears that the origin of the term in the American literature occurred as early as 1898 in an article by Hugo Munsterberg, predating the usage by Wilhelm Stern in 1911. The early references to the…

  14. Girl Number 20 Revisited: Feminist Literacies in New Hard Times

    ERIC Educational Resources Information Center

    Gonick, Marnina

    2007-01-01

    This paper revisits the question of "voice" in the context of neo-liberal social and educational reform. "Voice" has been one of the key concepts of feminist and critical pedagogies in the theory and practice of producing social transformation. I argue in this paper, that the political effectiveness of this concept needs to be…

  15. Facilitating Grade Acceleration: Revisiting the Wisdom of John Feldhusen

    ERIC Educational Resources Information Center

    Culross, Rita R.; Jolly, Jennifer L.; Winkler, Daniel

    2013-01-01

    This article revisits the 1986 Feldhusen, Proctor, and Black recommendations on grade skipping. These recommendations originally appeared as 12 guidelines. In this article, the guidelines are grouped into three general categories: how to screen accelerant candidates, how to engage with the adults in the acceleration process (e.g., teachers,…

  16. Bohr’s ‘Light and Life’ revisited

    NASA Astrophysics Data System (ADS)

    Nussenzveig, H. M.

    2015-11-01

    I revisit Niels Bohr’s famous 1932 ‘Light and Life’ lecture, confronting it with current knowledge. Topics covered include: life origin and evolution, quantum mechanics and life, brain and mind, consciousness and free will, and light as a tool for biology, with special emphasis on optical tweezers and their contributions to biophysics. Specialized knowledge of biology is not assumed.

  17. Antidote for Zero Tolerance: Revisiting a "Reclaiming" School.

    ERIC Educational Resources Information Center

    Farner, Conrad D.

    2002-01-01

    Reports on a revisit to the Frank Lloyd Wright Middle School, which implemented strategies to deal with disciplinary problems. The school continues to progress towards creating the type of reclaiming environment necessary to ensure the needs of all students. Strategies used include alternatives to zero tolerance policy; smaller teams of students;…

  18. The Importance of Being a Complement: CED Effects Revisited

    ERIC Educational Resources Information Center

    Jurka, Johannes

    2010-01-01

    This dissertation revisits subject island effects (Ross 1967, Chomsky 1973) cross-linguistically. Controlled acceptability judgment studies in German, English, Japanese and Serbian show that extraction out of specifiers is consistently degraded compared to extraction out of complements, indicating that the Condition on Extraction domains (CED,…

  19. Revisiting the Trust Effect in Urban Elementary Schools

    ERIC Educational Resources Information Center

    Adams, Curt M.; Forsyth, Patrick B.

    2013-01-01

    More than a decade after Goddard, Tschannen-Moran, and Hoy (2001) found that collective faculty trust in clients predicts student achievement in urban elementary schools, we sought to identify a plausible link for this relationship. Our purpose in revisiting the trust effect was twofold: (1) to test the main effect of collective faculty trust on…

  20. Evaluation of the Interactions between Water Extractable Soil Organic Matter and Metal Cations (Cu(II), Eu(III)) Using Excitation-Emission Matrix Combined with Parallel Factor Analysis

    PubMed Central

    Wei, Jing; Han, Lu; Song, Jing; Chen, Mengfang

    2015-01-01

    The objectives of this study were to evaluate the binding behavior of Cu(II) and Eu(III) with water extractable organic matter (WEOM) in soil, and assess the competitive effect of the cations. Excitation-emission matrix (EEM) fluorescence spectrometry was used in combination with parallel factor analysis (PARAFAC) to obtain four WEOM components: fulvic-like, humic-like, microbial degraded humic-like, and protein-like substances. Fluorescence titration experiments were performed to obtain the binding parameters of PARAFAC-derived components with Cu(II) and Eu(III). The conditional complexation stability constants (logKM) of Cu(II) with the four components ranged from 5.49 to 5.94, and the Eu(III) logKM values were between 5.26 to 5.81. The component-specific binding parameters obtained from competitive binding experiments revealed that Cu(II) and Eu(III) competed for the same binding sites on the WEOM components. These results would help understand the molecular binding mechanisms of Cu(II) and Eu(III) with WEOM in soil environment. PMID:26121300

  1. Detecting Cracks in Ceramic Matrix Composites by Electrical Resistance

    NASA Technical Reports Server (NTRS)

    Smith, Craig; Gyekenyesi, Andrew

    2011-01-01

    The majority of damage in SiC/SiC ceramic matrix composites subjected to monotonic tensile loads is in the form of distributed matrix cracks. These cracks initiate near stress concentrations, such as 90o fiber tows or large matrix pores and continue to accumulate with additional stress until matrix crack saturation is achieved. Such damage is difficult to detect with conventional nondestructive evaluation techniques (immersion ultrasonics, x-ray, etc.). Monitoring a specimen.s electrical resistance change provides an indirect approach for monitoring matrix crack density. Sylramic-iBN fiber- reinforced SiC composites with a melt infiltrated (MI) matrix were tensile tested at room temperature. Results showed an increase in resistance of more than 500% prior to fracture, which can be detected either in situ or post-damage. A relationship between resistance change and matrix crack density was also determined.

  2. Detecting Damage in Ceramic Matrix Composites Using Electrical Resistance

    NASA Technical Reports Server (NTRS)

    Smith, Craig E.; Gyekenyesi, Andrew

    2011-01-01

    The majority of damage in SiC/SiC ceramic matrix composites subjected to monotonic tensile loads is in the form of distributed matrix cracks. These cracks initiate near stress concentrations, such as 90 deg fiber tows or large matrix pores and continue to accumulate with additional stress until matrix crack saturation is achieved. Such damage is difficult to detect with conventional nondestructive evaluation techniques (immersion ultrasonics, x-ray, etc.). Monitoring a specimen.s electrical resistance change provides an indirect approach for monitoring matrix crack density. Sylramic-iBN fiber- reinforced SiC composites with a melt infiltrated (MI) matrix were tensile tested at room temperature. Results showed an increase in resistance of more than 500% prior to fracture, which can be detected either in situ or post-damage. A relationship between resistance change and matrix crack density was also determined.

  3. Evaluating the Use of the Inquiry Matrix.

    ERIC Educational Resources Information Center

    Priestley, Holly; Priestley, William J.; Sutman, Frank X.; Schmuckler, Joseph S.; Hilosky, Alexandra; White, Michael

    The Modified-Revised Science Teacher's Behavior Inventory (MR-STBI) was used in earlier studies to analyze the teaching strategies emphasized in instruction in science classrooms. This analysis showed changes in teaching strategies that occurred as a result of science teachers' professional development through longer-term modeled,…

  4. Evaluation of Bi as internal standard to minimize matrix effects on the direct determination of Pb in vinegar by graphite furnace atomic absorption spectrometry using Ru permanent modifier with co-injection of Pd/Mg(NO 3) 2

    NASA Astrophysics Data System (ADS)

    de Oliveira, Silvana Ruella; Neto, José Anchieta Gomes

    2007-09-01

    Bismuth was evaluated as an internal standard for the direct determination of Pb in vinegar by graphite furnace atomic absorption spectrometry using Ru as a permanent modifier with co-injection of Pd/Mg(NO 3) 2. The correlation coefficient of the graph plotted from the normalized absorbance signals of Bi versus Pb was r = 0.989. Matrix effects were evaluated by analyzing the slope ratios between the analytical curve obtained from reference solutions prepared in 0.2% (v/v) HNO 3 and analytical curves obtained from Pb additions in red and white wine vinegar samples. The calculated ratios were around 1.04 and 1.02 for analytical curves established applying an internal standard and 1.3 and 1.5 for analytical curves without. Analytical curves in the 2.5-15 μg L - 1 Pb concentration interval were established using the ratio Pb absorbance to Bi absorbance versus analyte concentration, and typical linear correlations of r = 0.999 were obtained. The proposed method was applied for direct determination of Pb in 18 commercial vinegar samples and the Pb concentration varied from 2.6 to 31 μg L - 1 . Results were in agreement at a 95% confidence level (paired t-test) with those obtained for digested samples. Recoveries of Pb added to vinegars varied from 96 to 108% with and from 72 to 86% without an internal standard. Two water standard reference materials diluted in vinegar sample were also analyzed and results were in agreement with certified values at a 95% confidence level. The characteristic mass was 40 pg Pb and the useful lifetime of the tube was around 1600 firings. The limit of detection was 0.3 μg L - 1 and the relative standard deviation was ≤ 3.8% and ≤ 8.3% ( n = 12) for a sample containing 10 μg L - 1 Pb with and without internal standard, respectively.

  5. Genetic Relationships Between Chondrules, Rims and Matrix

    NASA Technical Reports Server (NTRS)

    Huss, G. R.; Alexander, C. M. OD.; Palme, H.; Bland, P. A.; Wasson, J. T.

    2004-01-01

    The most primitive chondrites are composed of chondrules and chondrule fragments, various types of inclusions, discrete mineral grains, metal, sulfides, and fine-grained materials that occur as interchondrule matrix and as chondrule/inclusion rims. Understanding how these components are related is essential for understanding how chondrites and their constituents formed and were processed in the solar nebula. For example, were the first generations of chondrules formed by melting of matrix or matrix precursors? Did chondrule formation result in appreciable transfer of chondrule material into the matrix? Here, we consider three types of data: 1) compositional data for bulk chondrites and matrix, 2) mineralogical and textural information, and 3) the abundances and characteristics of presolar materials that reside in the matrix and rims. We use these data to evaluate the roles of evaporation and condensation, chondrule formation, mixing of different nebular components, and secondary processing both in the nebula and on the parent bodies. Our goal is to identify the things that are reasonably well established and to point out the areas that need additional work.

  6. Matrix Embedded Organic Synthesis

    NASA Astrophysics Data System (ADS)

    Kamakolanu, U. G.; Freund, F. T.

    2016-05-01

    In the matrix of minerals such as olivine, a redox reaction of the low-z elements occurs. Oxygen is oxidized to the peroxy state while the low-Z-elements become chemically reduced. We assign them a formula [CxHyOzNiSj]n- and call them proto-organics.

  7. Constructing the matrix

    NASA Astrophysics Data System (ADS)

    Elliott, John

    2012-09-01

    As part of our 'toolkit' for analysing an extraterrestrial signal, the facility for calculating structural affinity to known phenomena must be part of our core capabilities. Without such a resource, we risk compromising our potential for detection and decipherment or at least causing significant delay in the process. To create such a repository for assessing structural affinity, all known systems (language parameters) need to be structurally analysed to 'place' their 'system' within a relational communication matrix. This will need to include all known variants of language structure, whether 'living' (in current use) or ancient; this must also include endeavours to incorporate yet undeciphered scripts and non-human communication, to provide as complete a picture as possible. In creating such a relational matrix, post-detection decipherment will be assisted by a structural 'map' that will have the potential for 'placing' an alien communication with its nearest known 'neighbour', to assist subsequent categorisation of basic parameters as a precursor to decipherment. 'Universal' attributes and behavioural characteristics of known communication structure will form a range of templates (Elliott, 2001 [1] and Elliott et al., 2002 [2]), to support and optimise our attempt at categorising and deciphering the content of an extraterrestrial signal. Detection of the hierarchical layers, which comprise intelligent, complex communication, will then form a matrix of calculations that will ultimately score affinity through a relational matrix of structural comparison. In this paper we develop the rationales and demonstrate functionality with initial test results.

  8. Matrix product state renormalization

    NASA Astrophysics Data System (ADS)

    Bal, M.; Rams, M. M.; Zauner, V.; Haegeman, J.; Verstraete, F.

    2016-11-01

    The truncation or compression of the spectrum of Schmidt values is inherent to the matrix product state (MPS) approximation of one-dimensional quantum ground states. We provide a renormalization group picture by interpreting this compression as an application of Wilson's numerical renormalization group along the imaginary time direction appearing in the path integral representation of the state. The location of the physical index is considered as an impurity in the transfer matrix and static MPS correlation functions are reinterpreted as dynamical impurity correlations. Coarse-graining the transfer matrix is performed using a hybrid variational ansatz based on matrix product operators, combining ideas of MPS and the multiscale entanglement renormalization ansatz. Through numerical comparison with conventional MPS algorithms, we explicitly verify the impurity interpretation of MPS compression, as put forward by V. Zauner et al. [New J. Phys. 17, 053002 (2015), 10.1088/1367-2630/17/5/053002] for the transverse-field Ising model. Additionally, we motivate the conceptual usefulness of endowing MPS with an internal layered structure by studying restricted variational subspaces to describe elementary excitations on top of the ground state, which serves to elucidate a transparent renormalization group structure ingrained in MPS descriptions of ground states.

  9. High Resolution Rapid Revisits Insar Monitoring of Surface Deformation

    NASA Astrophysics Data System (ADS)

    Singhroy, V.; Li, J.; Charbonneau, F.

    2014-12-01

    Monitoring surface deformation on strategic energy and transportation corridors requires high resolution spatial and temporal InSAR images for mitigation and safety purposes. High resolution air photos, lidar and other satellite images are very useful in areas where the landslides can be fatal. Recently, radar interferometry (InSAR) techniques using more rapid revisit images from several radar satellites are increasingly being used in active deformation monitoring. The Canadian RADARSAT Constellation (RCM) is a three-satellite mission that will provide rapid revisits of four days interferometric (InSAR) capabilities that will be very useful for complex deformation monitoring. For instance, the monitoring of surface deformation due to permafrost activity, complex rock slide motion and steam assisted oil extraction will benefit from this new rapid revisit capability. This paper provide examples of how the high resolution (1-3 m) rapid revisit InSAR capabilities will improve our monitoring of surface deformation and provide insights in understanding triggering mechanisms. We analysed over a hundred high resolution InSAR images over a two year period on three geologically different sites with various configurations of topography, geomorphology, and geology conditions. We show from our analysis that the more frequent InSAR acquisitions are providing more information in understanding the rates of movement and failure process of permafrost triggered retrogressive thaw flows; the complex motion of an asymmetrical wedge failure of an active rock slide and the identification of over pressure zones related to oil extraction using steam injection. Keywords: High resolution, InSAR, rapid revisits, triggering mechanisms, oil extraction.

  10. Inverter Matrix for the Clementine Mission

    NASA Technical Reports Server (NTRS)

    Buehler, M. G.; Blaes, B. R.; Tardio, G.; Soli, G. A.

    1994-01-01

    An inverter matrix test circuit was designed for the Clementine space mission and is built into the RRELAX (Radiation and Reliability Assurance Experiment). The objective is to develop a circuit that will allow the evaluation of the CMOS FETs using a lean data set in the noisy spacecraft environment.

  11. Nonzero θ13 with unbroken μ -τ symmetry of the active neutrino mass matrix in the presence of a light sterile neutrino

    NASA Astrophysics Data System (ADS)

    Borah, Debasish

    2017-02-01

    We revisit the possibility of generating a nonzero reactor mixing angle in a scenario where there is a sterile neutrino at the eV scale apart from the usual three sub-eV scale active neutrinos. We show that the 3 ×3 active neutrino mass matrix can possess a μ -τ symmetry and can still be consistent with the nonzero value of the reactor mixing angle θ13 if this μ -τ symmetry is broken in the sterile neutrino sector. We first propose a simple model based on the discrete flavor symmetry A4×Z3×Z3' to realize such a scenario and then numerically evaluate the complete 3 +1 neutrino parameter space that allows such a possibility. We show that the possibility of generating a nonzero θ13 can, in general, remain valid even if the present 3 +1 neutrino global fit data get ruled out by future experiments. We also discuss the possible implications at neutrinoless double beta decay (0 ν β β ) experiments in view of the latest results from the KamLAND-Zen experiment.

  12. Revisiting the conundrum of trehalose stabilization.

    PubMed

    Katyal, Nidhi; Deep, Shashank

    2014-12-28

    Protein aggregation and loss of protein's biological functionality are manifestations of protein instability. Cosolvents, in particular trehalose, are widely accepted antidotes against such destabilization. Although numerous theories have been promulgated in the literature with regard to its mechanism of stabilization, the present scenario is still elusive in view of the discrepancies existing in them. To this end, we have revisited the conundrum and attempted to rationalize the mechanism by conducting thorough investigation of the effect of trehalose on the native, partially unfolded and denatured states of protein "Lysozyme" by means of molecular dynamic (MD) simulations under different temperature and concentration regimes. Two-dimensional contour plots along with principal component analysis suggest that trehalose molecules offer on-pathway stabilization unaltering the principal direction of protein's motion, although it slows down protein dynamics so that the protein gets trapped in the homogeneous ensemble of conformations closer to the native state. Free energy landscape reveals higher population of native compared to intermediate and denatured states. Delphi results and calculation of the preferential interaction parameter demonstrate that this relative stabilization of the native state can be ascribed to be the consequence of favourable interactions of trehalose with side chains of certain loci on the protein surface encompassing polar flexible residues. Stability of protein results from the observed difference in binding affinity of trehalose for native and denatured states of protein. Our findings are at variance with the common conception of relative destabilization of the denatured state. Rather, we provide evidence for relative stabilization of the native state. This stabilization is due to interplay of protein-trehalose, water-trehalose, water-water, protein-water and trehalose-trehalose interactions.

  13. The coordinate coherent states approach revisited

    SciTech Connect

    Miao, Yan-Gang Zhang, Shao-Jun

    2013-02-15

    We revisit the coordinate coherent states approach through two different quantization procedures in the quantum field theory on the noncommutative Minkowski plane. The first procedure, which is based on the normal commutation relation between an annihilation and creation operators, deduces that a point mass can be described by a Gaussian function instead of the usual Dirac delta function. However, we argue this specific quantization by adopting the canonical one (based on the canonical commutation relation between a field and its conjugate momentum) and show that a point mass should still be described by the Dirac delta function, which implies that the concept of point particles is still valid when we deal with the noncommutativity by following the coordinate coherent states approach. In order to investigate the dependence on quantization procedures, we apply the two quantization procedures to the Unruh effect and Hawking radiation and find that they give rise to significantly different results. Under the first quantization procedure, the Unruh temperature and Unruh spectrum are not deformed by noncommutativity, but the Hawking temperature is deformed by noncommutativity while the radiation specturm is untack. However, under the second quantization procedure, the Unruh temperature and Hawking temperature are untack but the both spectra are modified by an effective greybody (deformed) factor. - Highlights: Black-Right-Pointing-Pointer Suggest a canonical quantization in the coordinate coherent states approach. Black-Right-Pointing-Pointer Prove the validity of the concept of point particles. Black-Right-Pointing-Pointer Apply the canonical quantization to the Unruh effect and Hawking radiation. Black-Right-Pointing-Pointer Find no deformations in the Unruh temperature and Hawking temperature. Black-Right-Pointing-Pointer Provide the modified spectra of the Unruh effect and Hawking radiation.

  14. Revisiting mu suppression in autism spectrum disorder.

    PubMed

    Dumas, Guillaume; Soussignan, Robert; Hugueville, Laurent; Martinerie, Jacques; Nadel, Jacqueline

    2014-10-17

    Two aspects of the EEG literature lead us to revisit mu suppression in Autism Spectrum Disorder (ASD). First and despite the fact that the mu rhythm can be functionally segregated in two discrete sub-bands, 8-10 Hz and 10-12/13 Hz, mu-suppression in ASD has been analyzed as a homogeneous phenomenon covering the 8-13 Hz frequency. Second and although alpha-like activity is usually found across the entire scalp, ASD studies of action observation have focused on the central electrodes (C3/C4). The present study was aimed at testing on the whole brain the hypothesis of a functional dissociation of mu and alpha responses to the observation of human actions in ASD according to bandwidths. Electroencephalographic (EEG) mu and alpha responses to execution and observation of hand gestures were recorded on the whole scalp in high functioning subjects with ASD and typical subjects. When two bandwidths of the alpha-mu 8-13 Hz were distinguished, a different mu response to observation appeared for subjects with ASD in the upper sub-band over the sensorimotor cortex, whilst the lower sub-band responded similarly in the two groups. Source reconstructions demonstrated that this effect was related to a joint mu-suppression deficit over the occipito-parietal regions and an increase over the frontal regions. These findings suggest peculiarities in top-down response modulation in ASD and question the claim of a global dysfunction of the MNS in autism. This research also advocates for the use of finer grained analyses at both spatial and spectral levels for future directions in neurophysiological accounts of autism.

  15. SU-E-I-43: Photoelectric Cross Section Revisited

    SciTech Connect

    Haga, A; Nakagawa, K; Kotoku, J; Horikawa, Y

    2015-06-15

    Purpose: The importance of the precision in photoelectric cross-section value increases for recent developed technology such as dual energy computed tomography, in which some reconstruction algorithms require the energy dependence of the photo-absorption in each material composition of human being. In this study, we revisited the photoelectric cross-section calculation by self-consistent relativistic Hartree-Fock (HF) atomic model and compared with that widely distributed as “XCOM database” in National Institute of Standards and Technology, which was evaluated with localdensity approximation for electron-exchange (Fock)z potential. Methods: The photoelectric cross section can be calculated with the electron wave functions in initial atomic state (bound electron) and final continuum state (photoelectron). These electron states were constructed based on the selfconsistent HF calculation, where the repulsive Coulomb potential from the electron charge distribution (Hartree term) and the electron exchange potential with full electromagnetic interaction (Fock term) were included for the electron-electron interaction. The photoelectric cross sections were evaluated for He (Z=2), Be (Z=4), C (Z=6), O (Z=8), and Ne (Z=10) in energy range of 10keV to 1MeV. The Result was compared with XCOM database. Results: The difference of the photoelectric cross section between the present calculation and XCOM database was 8% at a maximum (in 10keV for Be). The agreement tends to be better as the atomic number increases. The contribution from each atomic shell has a considerable discrepancy with XCOM database except for K-shell. However, because the photoelectric cross section arising from K-shell is dominant, the net photoelectric cross section was almost insensitive to the different handling in Fock potential. Conclusion: The photoelectric cross-section program has been developed based on the fully self-consistent relativistic HF atomic model. Due to small effect on the Fock

  16. Matrix metalloproteinases in metabolic syndrome.

    PubMed

    Hopps, E; Caimi, G

    2012-03-01

    Metabolic syndrome is commonly accompanied by an elevated cardiovascular risk with high morbidity and mortality. The alterations of the arterial vasculature begin with endothelial dysfunction and lead to micro- and macrovascular complications. The remodeling of the endothelial basal membrane, that promotes erosion and thrombosis, has a multifactorial pathogenesis that includes leukocyte activation, increased oxidative stress and also an altered matrix metalloproteinases (MMPs) expression. MMPs are endopeptidases which degrade extracellular matrix proteins, such as collagen, gelatins, fibronectin and laminin. They can be secreted by several cells within the vascular wall, but macrophages are determinant in the atherosclerotic plaques. Their activity is regulated by tissue inhibitors of MMP (TIMPs) and also by other molecules, such as plasmin. MMPs could be implicated in plaque instability predisposing to vascular complications. It has been demonstrated that an impaired MMP or TIMP expression is associated with higher risk of all-cause mortality. A large number of studies evaluated MMPs pattern in obesity, diabetes mellitus, arterial hypertension and dyslipidemia, all of which define metabolic syndrome according to several Consensus Statement (i.e. IDF, ATP III, AHA). However, few research have been carried out on subjects with metabolic syndrome. The evidences of an improvement in MMP/TIMP ratio with diet, exercise and medical therapy should encourage further investigations with the intent to contrast the atherosclerotic process and to reduce morbidity and mortality of this kind of patients.

  17. Useful extremum principle for the variational calculation of matrix elements

    NASA Technical Reports Server (NTRS)

    Gerjuoy, E.; Rau, A. R. P.; Rosenberg, L.; Spruch, L.

    1974-01-01

    Variational principles are considered for the approximate evaluation of the diagonal matrix elements of an arbitrary known linear Hermitian operator. A method is derived that is immediately applicable to the variational determination of both the off-diagonal and diagonal matrix elements of normal and modified Green's functions.

  18. Random matrix theory

    NASA Astrophysics Data System (ADS)

    Edelman, Alan; Rao, N. Raj

    Random matrix theory is now a big subject with applications in many disciplines of science, engineering and finance. This article is a survey specifically oriented towards the needs and interests of a numerical analyst. This survey includes some original material not found anywhere else. We include the important mathematics which is a very modern development, as well as the computational software that is transforming the theory into useful practice.

  19. Metal Matrix Composites

    NASA Astrophysics Data System (ADS)

    Mortensen, Andreas; Llorca, Javier

    2010-08-01

    In metal matrix composites, a metal is combined with another, often nonmetallic, phase to produce a novel material having attractive engineering attributes of its own. A subject of much research in the 1980s and 1990s, this class of materials has, in the past decade, increased significantly in variety. Copper matrix composites, layered composites, high-conductivity composites, nanoscale composites, microcellular metals, and bio-derived composites have been added to a palette that, ten years ago, mostly comprised ceramic fiber- or particle-reinforced light metals together with some well-established engineering materials, such as WC-Co cermets. At the same time, research on composites such as particle-reinforced aluminum, aided by novel techniques such as large-cell 3-D finite element simulation or computed X-ray microtomography, has served as a potent vehicle for the elucidation of the mechanics of high-contrast two-phase elastoplastic materials, with implications that range well beyond metal matrix composites.

  20. Evaluation of the Bruker Biotyper and Vitek MS Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry Systems for Identification of Nonfermenting Gram-Negative Bacilli Isolated from Cultures from Cystic Fibrosis Patients

    PubMed Central

    Marko, Daniel C.; Saffert, Ryan T.; Cunningham, Scott A.; Hyman, Jay; Walsh, John; Arbefeville, Sophie; Howard, Wanita; Pruessner, Jon; Safwat, Nedal; Cockerill, Franklin R.; Bossler, Aaron D.; Patel, Robin

    2012-01-01

    The Bruker Biotyper and Vitek MS matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry (MS) instruments were evaluated for the identification of nonfermenting Gram-negative bacilli (NFGNB) by a blinded comparison to conventional biochemical or molecular methods. Two hundred NFGNB that were recovered from cultures from cystic fibrosis patients in the University of Iowa Health Care (UIHC) Microbiology Laboratory between 1 January 2006 and 31 October 2010 were sent to Mayo Clinic for analysis with the Bruker Biotyper (software version 3.0) and to bioMérieux for testing with Vitek MS (SARAMIS database version 3.62). If two attempts at direct colony testing failed to provide an acceptable MALDI-TOF identification, an extraction procedure was performed. The MS identifications from both of these systems were provided to UIHC for comparison to the biochemical or molecular identification that had been reported in the patient record. Isolates with discordant results were analyzed by 16S rRNA gene sequencing at UIHC. After discrepancy testing, the Bruker Biotyper result agreed with the biochemical or molecular method, with 72.5% of isolates to the species level, 5.5% to the complex level, and 19% to the genus level (3% not identified). The level of agreement for Vitek MS was 80% species, 3.5% complex, 6% genus, and 3.5% family (7% not identified). Both MS systems provided rapid (≤3 min per isolate) and reliable identifications. The agreement of combined species/complex/genus-level identification with the reference method was higher for the Bruker Biotyper (97% versus 89.5%, P = 0.004) but required an extraction step more often. Species-level agreement with the reference method was similar for both MS systems (72.5% and 80%, P = 0.099). PMID:22495566

  1. Evaluation of the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry Bruker Biotyper for identification of Penicillium marneffei, Paecilomyces species, Fusarium solani, Rhizopus species, and Pseudallescheria boydii.

    PubMed

    Chen, Ying-Sheng; Liu, Yen-Hung; Teng, Shih-Hua; Liao, Chun-Hsing; Hung, Chien-Ching; Sheng, Wang-Huei; Teng, Lee-Jene; Hsueh, Po-Ren

    2015-01-01

    We evaluated the performance of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), the MALDI Bruker Biotyper system (microflex LT; Bruker Daltonik GmbH, Bremen, Germany), on the identification of 50 isolates of clinically encountered molds, including Penicillium marneffei (n = 28), Paecilomyces species (n = 12), Fusarium solani (n = 6), Rhizopus species (n = 3), and Pseudallescheria boydii (n = 1). The isolates were identified to species levels by sequence analysis of the internal transcribed spacer (ITS) regions using primers ITS1 and ITS4. None of the 28 genetically well characterized isolates of P. marneffei were identified as P. marneffei by MALDI-TOF MS, because P. marneffei was not present in either Bruker general library (DB 5627) or Bruker filamentous fungi library V1.0. However, the rate of accurate identification as P. marneffei (score value ≥ 2.000) was 85.7% based on newly created database from one P. marneffei strain (NTUH-3370) by MALDI Biotyper system. Sequencing analysis of these 22 non-P. marneffei isolates of molds revealed seven Paecilomyces variotii, six F. solani, four Paecilomyces lilacinus, and one each of Paecilomyces sinensis, Rhizopus arrhizus, R. oryzae, R. microspores, and P. boydii. Although all the seven P. variotii isolates, four of the six F. solani, two of the four P. lilacinus, and two of the three isolates of Rhizopus species, and the P. boydii isolate had concordant identification results between MALDI-TOF MS and sequencing analysis, the score values of these isolates were all of <1.700. This study indicated that the MALDI Bruker Biotyper is ineffective for identifying P. marneffei and other unusual molds because of the current database limitations. Therefore, it is necessary to continuously update the MALDI-TOF MS databases.

  2. Superfund chemical data matrix, 1996

    SciTech Connect

    1996-06-01

    The Superfund Chemical Data Matrix (SCDM) is a source for factor values and benchmark values applied when evaluating potential National Priorities List (NPL) sites using the Hazard Ranking System. The HRS assigns factor values for toxicity, gas migration potential, gas and ground water mobility, surface water persistence, and bioaccumulation potential based on the physical, chemical, and radiological properties of hazardous substances present at a site. Hazardous substances, as defined for HRS purposes, are CERCLA hazardous substances plus CERCLA pollutants and contaminants. The HRS also assigns extra weight to targets with exposure levels to hazardous substances that are at or above benchmarks. These benchmarks include both risk-based screening concentrations and concentrations specified in regulatory limits for the hazardous substances present at a site for a particular migration pathway.

  3. Thermoplastic matrix composite processing model

    NASA Technical Reports Server (NTRS)

    Dara, P. H.; Loos, A. C.

    1985-01-01

    The effects the processing parameters pressure, temperature, and time have on the quality of continuous graphite fiber reinforced thermoplastic matrix composites were quantitatively accessed by defining the extent to which intimate contact and bond formation has occurred at successive ply interfaces. Two models are presented predicting the extents to which the ply interfaces have achieved intimate contact and cohesive strength. The models are based on experimental observation of compression molded laminates and neat resin conditions, respectively. Identified as the mechanism explaining the phenomenon by which the plies bond to themselves is the theory of autohesion (or self diffusion). Theoretical predictions from the Reptation Theory between autohesive strength and contact time are used to explain the effects of the processing parameters on the observed experimental strengths. The application of a time-temperature relationship for autohesive strength predictions is evaluated. A viscoelastic compression molding model of a tow was developed to explain the phenomenon by which the prepreg ply interfaces develop intimate contact.

  4. Application of transmissibility matrix and random matrix to Bayesian system identification with response measurements only

    NASA Astrophysics Data System (ADS)

    Yan, Wang-Ji; Katafygiotis, Lambros S.

    2016-10-01

    The problem of stochastic system identification utilizing response measurements only is considered in this paper. A negative log-likelihood function utilized to determine the posterior most probable parameters and their associated uncertainties is formulated by incorporating transmissibility matrix concept, random matrix theory and Bayes’ theorem. A numerically iterative coupled method involving the optimization of the parameters in groups is proposed so as to reduce the dimension of the numerical optimization problem involved. The initial guess for the parameters to be optimized is also properly estimated through asymptotic analysis. One novel feature of the proposed method is to avoid repeated time-consuming evaluation of the determinant and inverse of the covariance matrix during optimization due to exploring the statistical properties of the trace of Wishart matrix. The proposed method requires no information about the model of the external input. The theory described in this work is illustrated with synthetic data and field data measured from a laboratory model installed with wireless sensors.

  5. t matrix of metallic wire structures

    SciTech Connect

    Zhan, T. R. Chui, S. T.

    2014-04-14

    To study the electromagnetic resonance and scattering properties of complex structures of which metallic wire structures are constituents within multiple scattering theory, the t matrix of individual structures is needed. We have recently developed a rigorous and numerically efficient equivalent circuit theory in which retardation effects are taken into account for metallic wire structures. Here, we show how the t matrix can be calculated analytically within this theory. We illustrate our method with the example of split ring resonators. The density of states and cross sections for scattering and absorption are calculated, which are shown to be remarkably enhanced at resonant frequencies. The t matrix serves as the basic building block to evaluate the interaction of wire structures within the framework of multiple scattering theory. This will open the door to efficient design and optimization of assembly of wire structures.

  6. t matrix of metallic wire structures

    NASA Astrophysics Data System (ADS)

    Zhan, T. R.; Chui, S. T.

    2014-04-01

    To study the electromagnetic resonance and scattering properties of complex structures of which metallic wire structures are constituents within multiple scattering theory, the t matrix of individual structures is needed. We have recently developed a rigorous and numerically efficient equivalent circuit theory in which retardation effects are taken into account for metallic wire structures. Here, we show how the t matrix can be calculated analytically within this theory. We illustrate our method with the example of split ring resonators. The density of states and cross sections for scattering and absorption are calculated, which are shown to be remarkably enhanced at resonant frequencies. The t matrix serves as the basic building block to evaluate the interaction of wire structures within the framework of multiple scattering theory. This will open the door to efficient design and optimization of assembly of wire structures.

  7. The Stern-Gerlach experiment revisited

    NASA Astrophysics Data System (ADS)

    Schmidt-Böcking, Horst; Schmidt, Lothar; Lüdde, Hans Jürgen; Trageser, Wolfgang; Templeton, Alan; Sauer, Tilman

    2016-12-01

    experimental example for such directional quantization in scattering processes is shown. Last not least, the early history of the "almost" discovery of the electron spin in the SGE is revisited.

  8. Alkaline phosphatase revisited: hydrolysis of alkyl phosphates.

    PubMed

    O'Brien, Patrick J; Herschlag, Daniel

    2002-03-05

    Escherichia coli alkaline phosphatase (AP) is the prototypical two metal ion catalyst with two divalent zinc ions bound approximately 4 A apart in the active site. Studies spanning half a century have elucidated many structural and mechanistic features of this enzyme, rendering it an attractive model for investigating the potent catalytic power of bimetallic centers. Unfortunately, fundamental mechanistic features have been obscured by limitations with the standard assays. These assays generate concentrations of inorganic phosphate (P(i)) in excess of its inhibition constant (K(i) approximately 1 muM). This tight binding by P(i) has affected the majority of published kinetic constants. Furthermore, binding limits k(cat)/K(m) for reaction of p-nitrophenyl phosphate, the most commonly employed substrate. We describe a sensitive (32)P-based assay for hydrolysis of alkyl phosphates that avoids the complication of product inhibition. We have revisited basic mechanistic features of AP with these alkyl phosphate substrates. The results suggest that the chemical step for phosphorylation of the enzyme limits k(cat)/K(m). The pH-rate profile and additional results suggest that the serine nucleophile is active in its anionic form and has a pK(a) of < or = 5.5 in the free enzyme. An inactivating pK(a) of 8.0 is observed for binding of both substrates and inhibitors, and we suggest that this corresponds to ionization of a zinc-coordinated water molecule. Counter to previous suggestions, inorganic phosphate dianion appears to bind to the highly charged AP active site at least as strongly as the trianion. The dependence of k(cat)/K(m) on the pK(a) of the leaving group follows a Brønsted correlation with a slope of beta(lg) = -0.85 +/- 0.1, differing substantially from the previously reported value of -0.2 obtained from data with a less sensitive assay. This steep leaving group dependence is consistent with a largely dissociative transition state for AP-catalyzed hydrolysis of

  9. Pair correlation and twin primes revisited

    PubMed Central

    Conrey, Brian

    2016-01-01

    We establish a connection between the conjectural two-over-two ratios formula for the Riemann zeta-function and a conjecture concerning correlations of a certain arithmetic function. Specifically, we prove that the ratios conjecture and the arithmetic correlations conjecture imply the same result. This casts a new light on the underpinnings of the ratios conjecture, which previously had been motivated by analogy with formulae in random matrix theory and by a heuristic recipe. PMID:27843409

  10. On the Matrix Exponential Function

    ERIC Educational Resources Information Center

    Hou, Shui-Hung; Hou, Edwin; Pang, Wan-Kai

    2006-01-01

    A novel and simple formula for computing the matrix exponential function is presented. Specifically, it can be used to derive explicit formulas for the matrix exponential of a general matrix A satisfying p(A) = 0 for a polynomial p(s). It is ready for use in a classroom and suitable for both hand as well as symbolic computation.

  11. Max-min distance nonnegative matrix factorization.

    PubMed

    Wang, Jim Jing-Yan; Gao, Xin

    2015-01-01

    Nonnegative Matrix Factorization (NMF) has been a popular representation method for pattern classification problems. It tries to decompose a nonnegative matrix of data samples as the product of a nonnegative basis matrix and a nonnegative coefficient matrix. The columns of the coefficient matrix can be used as new representations of these data samples. However, traditional NMF methods ignore class labels of the data samples. In this paper, we propose a novel supervised NMF algorithm to improve the discriminative ability of the new representation by using the class labels. Using the class labels, we separate all the data sample pairs into within-class pairs and between-class pairs. To improve the discriminative ability of the new NMF representations, we propose to minimize the maximum distance of the within-class pairs in the new NMF space, and meanwhile to maximize the minimum distance of the between-class pairs. With this criterion, we construct an objective function and optimize it with regard to basis and coefficient matrices, and slack variables alternatively, resulting in an iterative algorithm. The proposed algorithm is evaluated on three pattern classification problems and experiment results show that it outperforms the state-of-the-art supervised NMF methods.

  12. Hydrodynamic limit of Wigner-Poisson kinetic theory: Revisited

    NASA Astrophysics Data System (ADS)

    Akbari-Moghanjoughi, M.

    2015-02-01

    In this paper, we revisit the hydrodynamic limit of the Langmuir wave dispersion relation based on the Wigner-Poisson model in connection with that obtained directly from the original Lindhard dielectric function based on the random-phase-approximation. It is observed that the (fourth-order) expansion of the exact Lindhard dielectric constant correctly reduces to the hydrodynamic dispersion relation with an additional term of fourth-order, beside that caused by the quantum diffraction effect. It is also revealed that the generalized Lindhard dielectric theory accounts for the recently discovered Shukla-Eliasson attractive potential (SEAP). However, the expansion of the exact Lindhard static dielectric function leads to a k4 term of different magnitude than that obtained from the linearized quantum hydrodynamics model. It is shown that a correction factor of 1/9 should be included in the term arising from the quantum Bohm potential of the momentum balance equation in fluid model in order for a correct plasma dielectric response treatment. Finally, it is observed that the long-range oscillatory screening potential (Friedel oscillations) of type cos ( 2 k F r ) / r 3 , which is a consequence of the divergence of the dielectric function at point k = 2kF in a quantum plasma, arises due to the finiteness of the Fermi-wavenumber and is smeared out in the limit of very high electron number-densities, typical of white dwarfs and neutron stars. In the very low electron number-density regime, typical of semiconductors and metals, where the Friedel oscillation wavelength becomes much larger compared to the interparticle distances, the SEAP appears with a much deeper potential valley. It is remarked that the fourth-order approximate Lindhard dielectric constant approaches that of the linearized quantum hydrodynamic in the limit if very high electron number-density. By evaluation of the imaginary part of the Lindhard dielectric function, it is shown that the Landau

  13. 14 CFR 1214.205 - Revisit and/or retrieval services.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 5 2011-01-01 2010-01-01 true Revisit and/or retrieval services. 1214.205... Substantial Investment in the STS Program § 1214.205 Revisit and/or retrieval services. These services will be... dedicated price will be charged. If the user's retrieval requirement is such that it can be accomplished...

  14. 14 CFR 1214.205 - Revisit and/or retrieval services.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 5 2010-01-01 2010-01-01 false Revisit and/or retrieval services. 1214.205... Substantial Investment in the STS Program § 1214.205 Revisit and/or retrieval services. These services will be... dedicated price will be charged. If the user's retrieval requirement is such that it can be accomplished...

  15. 14 CFR 1214.205 - Revisit and/or retrieval services.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 5 2012-01-01 2012-01-01 false Revisit and/or retrieval services. 1214.205... Substantial Investment in the STS Program § 1214.205 Revisit and/or retrieval services. These services will be... dedicated price will be charged. If the user's retrieval requirement is such that it can be accomplished...

  16. 14 CFR § 1214.205 - Revisit and/or retrieval services.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 5 2014-01-01 2014-01-01 false Revisit and/or retrieval services. § 1214... Have Made Substantial Investment in the STS Program § 1214.205 Revisit and/or retrieval services. These..., the full dedicated price will be charged. If the user's retrieval requirement is such that it can...

  17. 14 CFR 1214.205 - Revisit and/or retrieval services.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 5 2013-01-01 2013-01-01 false Revisit and/or retrieval services. 1214.205... Substantial Investment in the STS Program § 1214.205 Revisit and/or retrieval services. These services will be... dedicated price will be charged. If the user's retrieval requirement is such that it can be accomplished...

  18. Enthalpy-Entropy Compensation (EEC) Effect: A Revisit.

    PubMed

    Pan, Animesh; Biswas, Tapas; Rakshit, Animesh K; Moulik, Satya P

    2015-12-31

    A short account of the developments and perspectives of IKR (iso-kinetic relation) and EEC (enthalpy (H) - entropy (S) compensation) has been presented. The IKR and EEC are known to be extra thermodynamic or empirical correlations though linear H-S correlation can be thermodynamically deduced. Attempt has also been made to explain the phenomena in terms of statistical thermodynamics. In this study, we have briefly revisited the fundamentals of both IKR and EEC from kinetic and thermodynamic grounds. A detailed revisit of the EEC phenomenon on varied kinetic and equilibrium processes has been also presented. Possible correlations among the free energy (ΔG), enthalpy (ΔH), and entropy (ΔS) changes of different similar and nonsimilar chemical processes under varied conditions have been discussed with possible future projections.

  19. The cellulose resource matrix.

    PubMed

    Keijsers, Edwin R P; Yılmaz, Gülden; van Dam, Jan E G

    2013-03-01

    The emerging biobased economy is causing shifts from mineral fossil oil based resources towards renewable resources. Because of market mechanisms, current and new industries utilising renewable commodities, will attempt to secure their supply of resources. Cellulose is among these commodities, where large scale competition can be expected and already is observed for the traditional industries such as the paper industry. Cellulose and lignocellulosic raw materials (like wood and non-wood fibre crops) are being utilised in many industrial sectors. Due to the initiated transition towards biobased economy, these raw materials are intensively investigated also for new applications such as 2nd generation biofuels and 'green' chemicals and materials production (Clark, 2007; Lange, 2007; Petrus & Noordermeer, 2006; Ragauskas et al., 2006; Regalbuto, 2009). As lignocellulosic raw materials are available in variable quantities and qualities, unnecessary competition can be avoided via the choice of suitable raw materials for a target application. For example, utilisation of cellulose as carbohydrate source for ethanol production (Kabir Kazi et al., 2010) avoids the discussed competition with easier digestible carbohydrates (sugars, starch) deprived from the food supply chain. Also for cellulose use as a biopolymer several different competing markets can be distinguished. It is clear that these applications and markets will be influenced by large volume shifts. The world will have to reckon with the increase of competition and feedstock shortage (land use/biodiversity) (van Dam, de Klerk-Engels, Struik, & Rabbinge, 2005). It is of interest - in the context of sustainable development of the bioeconomy - to categorize the already available and emerging lignocellulosic resources in a matrix structure. When composing such "cellulose resource matrix" attention should be given to the quality aspects as well as to the available quantities and practical possibilities of processing the

  20. What Is Inflammatory Breast Cancer? Revisiting the Case Definition

    DTIC Science & Technology

    2010-03-03

    Cancer? Revisiting the Case Definition Paul H. Levine 1 ,*, Ladan Zolfaghari 1 , Heather Young 1 , Muhannad Hafi 1 , Timothy Cannon 1 , Chitra Ganesan 1 ...Carmela Veneroso 1 , Rachel Brem 2 and Mark Sherman 3 1 The Department of Epidemiology and Biostatistics, George Washington University School of...gwumc.edu; Tel.: + 1 -202-994-4582; Fax: + 1 -202-994-0082. Received: 14 December 2009; in revised form: 10 February 2010 / Accepted: 1 March 2010

  1. Non linear evolution: revisiting the solution in the saturation region

    NASA Astrophysics Data System (ADS)

    Contreras, Carlos; Levin, Eugene; Meneses, Rodrigo

    2014-10-01

    In this paper we revisit the problem of the solution to Balitsky-Kovchegov equation deeply in the saturation domain. We find that solution has the form given in ref. [23] but it depends on variable and the value of Const is calculated in this paper. We propose the solution for full BFKL kernel at large in the entire kinematic region that satisfies the McLerran-Venugopalan-type [3-7] initial condition.

  2. Discussion of "Computational Electrocardiography: Revisiting Holter ECG Monitoring".

    PubMed

    Baumgartner, Christian; Caiani, Enrico G; Dickhaus, Hartmut; Kulikowski, Casimir A; Schiecke, Karin; van Bemmel, Jan H; Witte, Herbert

    2016-08-05

    This article is part of a For-Discussion-Section of Methods of Information in Medicine about the paper "Computational Electrocardiography: Revisiting Holter ECG Monitoring" written by Thomas M. Deserno and Nikolaus Marx. It is introduced by an editorial. This article contains the combined commentaries invited to independently comment on the paper of Deserno and Marx. In subsequent issues the discussion can continue through letters to the editor.

  3. Indoor air and human health revisited: A recent IAQ symposium

    SciTech Connect

    Gammage, R.B.

    1994-12-31

    Indoor Air and Human Health Revisited was a speciality symposium examining the scientific underpinnings of sensory and sensitivity effects, allergy and respiratory disease, neurotoxicity and cancer. An organizing committee selected four persons to chain the sessions and invite experts to give state-of-the-art presentations that will be published as a book. A summary of the presentations is made and some critical issues identified.

  4. Supported Molecular Matrix Electrophoresis.

    PubMed

    Matsuno, Yu-Ki; Kameyama, Akihiko

    2015-01-01

    Mucins are difficult to separate using conventional gel electrophoresis methods such as SDS-PAGE and agarose gel electrophoresis, owing to their large size and heterogeneity. On the other hand, cellulose acetate membrane electrophoresis can separate these molecules, but is not compatible with glycan analysis. Here, we describe a novel membrane electrophoresis technique, termed "supported molecular matrix electrophoresis" (SMME), in which a porous polyvinylidene difluoride (PVDF) membrane filter is used to achieve separation. This description includes the separation, visualization, and glycan analysis of mucins with the SMME technique.

  5. Exact two-component Hamiltonians revisited.

    PubMed

    Liu, Wenjian; Peng, Daoling

    2009-07-21

    Two routes for deriving the exact two-component Hamiltonians are compared. In the first case, as already known, we start directly from the matrix representation of the Dirac operator in a restricted kinetically balanced basis and make a single block diagonalization. In the second case, not considered before, we start instead from the Foldy-Wouthuysen operator and make proper use of resolutions of the identity. The expressions are surprisingly different. It turns out that a mistake was made in the former formulation when going from the Dirac to the Schrodinger picture. The two formulations become equivalent after the mistake is corrected.

  6. Exact two-component Hamiltonians revisited

    SciTech Connect

    Liu Wenjian; Peng Daoling

    2009-07-21

    Two routes for deriving the exact two-component Hamiltonians are compared. In the first case, as already known, we start directly from the matrix representation of the Dirac operator in a restricted kinetically balanced basis and make a single block diagonalization. In the second case, not considered before, we start instead from the Foldy-Wouthuysen operator and make proper use of resolutions of the identity. The expressions are surprisingly different. It turns out that a mistake was made in the former formulation when going from the Dirac to the Schroedinger picture. The two formulations become equivalent after the mistake is corrected.

  7. Medial vascular calcification revisited: review and perspectives

    PubMed Central

    Lanzer, Peter; Boehm, Manfred; Sorribas, Victor; Thiriet, Marc; Janzen, Jan; Zeller, Thomas; St Hilaire, Cynthia; Shanahan, Catherine

    2014-01-01

    Vascular calcifications (VCs) are actively regulated biological processes associated with crystallization of hydroxyapatite in the extracellular matrix and in cells of the media (VCm) or intima (VCi) of the arterial wall. Both patterns of VC often coincide and occur in patients with type II diabetes, chronic kidney disease, and other less frequent disorders; VCs are also typical in senile degeneration. In this article, we review the current state of knowledge about the pathology, molecular biology, and nosology of VCm, expand on potential mechanisms responsible for poor prognosis, and expose some of the directions for future research in this area. PMID:24740885

  8. Revisiting the revisit: added evidence for a social chemosignal in human emotional tears.

    PubMed

    Sobel, Noam

    2017-01-01

    In a study by Gelstein et al., we found that human emotional tears act as a social chemosignal. In the first of three different experiments in that study we observed that sniffing women's emotional tears reduced the sexual attractiveness attributed by men to pictures of women's faces. In a study partly titled "Chemosignaling effects of human tears revisited", Gračanin et al. claim failed replication of this effect in a series of experiments, one they described as "exactly the same procedure" as Gelstein. Given that Gračanin et al. refused our extended offer to jointly replicate the experiment at our expense, we can merely comment on their effort. We find that Gračanin, who are not a chemosignaling laboratory, used methodology that falls short of standards typically applied in chemosignaling research. Thus, their experiments were profoundly different from Gelstein. Finally, we found that in reanalysing their raw data we could in fact replicate the effect from Gelstein. Thus, we conclude that the failed replication in Gračanin is neither a replication nor failed.

  9. Development and Performance Evaluations of HfO2-Si and Rare Earth-Si Based Environmental Barrier Bond Coat Systems for SiC/SiC Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming

    2014-01-01

    Ceramic environmental barrier coatings (EBC) and SiCSiC ceramic matrix composites (CMCs) will play a crucial role in future aircraft propulsion systems because of their ability to significantly increase engine operating temperatures, improve component durability, reduce engine weight and cooling requirements. Advanced EBC systems for SiCSiC CMC turbine and combustor hot section components are currently being developed to meet future turbine engine emission and performance goals. One of the significant material development challenges for the high temperature CMC components is to develop prime-reliant, high strength and high temperature capable environmental barrier coating bond coat systems, since the current silicon bond coat cannot meet the advanced EBC-CMC temperature and stability requirements. In this paper, advanced NASA HfO2-Si based EBC bond coat systems for SiCSiC CMC combustor and turbine airfoil applications are investigated. The coating design approach and stability requirements are specifically emphasized, with the development and implementation focusing on Plasma Sprayed (PS) and Electron Beam-Physic Vapor Deposited (EB-PVD) coating systems and the composition optimizations. High temperature properties of the HfO2-Si based bond coat systems, including the strength, fracture toughness, creep resistance, and oxidation resistance were evaluated in the temperature range of 1200 to 1500 C. Thermal gradient heat flux low cycle fatigue and furnace cyclic oxidation durability tests were also performed at temperatures up to 1500 C. The coating strength improvements, degradation and failure modes of the environmental barrier coating bond coat systems on SiCSiC CMCs tested in simulated stress-environment interactions are briefly discussed and supported by modeling. The performance enhancements of the HfO2-Si bond coat systems with rare earth element dopants and rare earth-silicon based bond coats are also highlighted. The advanced bond coat systems, when

  10. Simulating runoff under changing climatic conditions: Revisiting an apparent deficiency of conceptual rainfall-runoff models

    NASA Astrophysics Data System (ADS)

    Fowler, Keirnan J. A.; Peel, Murray C.; Western, Andrew W.; Zhang, Lu; Peterson, Tim J.

    2016-03-01

    Hydrologic models have potential to be useful tools in planning for future climate variability. However, recent literature suggests that the current generation of conceptual rainfall runoff models tend to underestimate the sensitivity of runoff to a given change in rainfall, leading to poor performance when evaluated over multiyear droughts. This research revisited this conclusion, investigating whether the observed poor performance could be due to insufficient model calibration and evaluation techniques. We applied an approach based on Pareto optimality to explore trade-offs between model performance in different climatic conditions. Five conceptual rainfall runoff model structures were tested in 86 catchments in Australia, for a total of 430 Pareto analyses. The Pareto results were then compared with results from a commonly used model calibration and evaluation method, the Differential Split Sample Test. We found that the latter often missed potentially promising parameter sets within a given model structure, giving a false negative impression of the capabilities of the model. This suggests that models may be more capable under changing climatic conditions than previously thought. Of the 282[347] cases of apparent model failure under the split sample test using the lower [higher] of two model performance criteria trialed, 155[120] were false negatives. We discuss potential causes of remaining model failures, including the role of data errors. Although the Pareto approach proved useful, our aim was not to suggest an alternative calibration strategy, but to critically assess existing methods of model calibration and evaluation. We recommend caution when interpreting split sample results.

  11. Data from acellular human heart matrix.

    PubMed

    Sánchez, Pedro L; Fernández-Santos, M Eugenia; Espinosa, M Angeles; González-Nicolas, M Angeles; Acebes, Judith R; Costanza, Salvatore; Moscoso, Isabel; Rodríguez, Hugo; García, Julio; Romero, Jesús; Kren, Stefan M; Bermejo, Javier; Yotti, Raquel; Del Villar, Candelas Pérez; Sanz-Ruiz, Ricardo; Elizaga, Jaime; Taylor, Doris A; Fernández-Avilés, Francisco

    2016-09-01

    Perfusion decellularization of cadaveric hearts removes cells and generates a cell-free extracellular matrix scaffold containing acellular vascular conduits, which are theoretically sufficient to perfuse and support tissue-engineered heart constructs. This article contains additional data of our experience decellularizing and testing structural integrity and composition of a large series of human hearts, "Acellular human heart matrix: a critical step toward whole heat grafts" (Sanchez et al., 2015) [1]. Here we provide the information about the heart decellularization technique, the valve competence evaluation of the decellularized scaffolds, the integrity evaluation of epicardial and myocardial coronary circulation, the pressure volume measurements, the primers used to assess cardiac muscle gene expression and, the characteristics of donors, donor hearts, scaffolds and perfusion decellularization process.

  12. Relic neutrino decoupling with flavour oscillations revisited

    SciTech Connect

    Salas, Pablo F. de; Pastor, Sergio

    2016-07-28

    We study the decoupling process of neutrinos in the early universe in the presence of three-flavour oscillations. The evolution of the neutrino spectra is found by solving the corresponding momentum-dependent kinetic equations for the neutrino density matrix, including for the first time the proper collision integrals for both diagonal and off-diagonal elements. This improved calculation modifies the evolution of the off-diagonal elements of the neutrino density matrix and changes the deviation from equilibrium of the frozen neutrino spectra. However, it does not vary the contribution of neutrinos to the cosmological energy density in the form of radiation, usually expressed in terms of the effective number of neutrinos, N{sub eff}. We find a value of N{sub eff}=3.045, in agreement with previous theoretical calculations and consistent with the latest analysis of Planck data. This result does not depend on the ordering of neutrino masses. We also consider the effect of non-standard neutrino-electron interactions (NSI), predicted in many theoretical models where neutrinos acquire mass. For two sets of NSI parameters allowed by present data, we find that N{sub eff} can be reduced down to 3.040 or enhanced up to 3.059.

  13. Relic neutrino decoupling with flavour oscillations revisited

    NASA Astrophysics Data System (ADS)

    de Salas, Pablo F.; Pastor, Sergio

    2016-07-01

    We study the decoupling process of neutrinos in the early universe in the presence of three-flavour oscillations. The evolution of the neutrino spectra is found by solving the corresponding momentum-dependent kinetic equations for the neutrino density matrix, including for the first time the proper collision integrals for both diagonal and off-diagonal elements. This improved calculation modifies the evolution of the off-diagonal elements of the neutrino density matrix and changes the deviation from equilibrium of the frozen neutrino spectra. However, it does not vary the contribution of neutrinos to the cosmological energy density in the form of radiation, usually expressed in terms of the effective number of neutrinos, Neff. We find a value of Neff = 3.045, in agreement with previous theoretical calculations and consistent with the latest analysis of Planck data. This result does not depend on the ordering of neutrino masses. We also consider the effect of non-standard neutrino-electron interactions (NSI), predicted in many theoretical models where neutrinos acquire mass. For two sets of NSI parameters allowed by present data, we find that Neff can be reduced down to 3.040 or enhanced up to 3.059.

  14. Ceramic matrix and resin matrix composites: A comparison

    NASA Technical Reports Server (NTRS)

    Hurwitz, Frances I.

    1987-01-01

    The underlying theory of continuous fiber reinforcement of ceramic matrix and resin matrix composites, their fabrication, microstructure, physical and mechanical properties are contrasted. The growing use of organometallic polymers as precursors to ceramic matrices is discussed as a means of providing low temperature processing capability without the fiber degradation encountered with more conventional ceramic processing techniques. Examples of ceramic matrix composites derived from particulate-filled, high char yield polymers and silsesquioxane precursors are provided.

  15. Perturbative approach to covariance matrix of the matter power spectrum

    SciTech Connect

    Mohammed, Irshad; Seljak, Uros; Vlah, Zvonimir

    2016-06-30

    We evaluate the covariance matrix of the matter power spectrum using perturbation theory up to dominant terms at 1-loop order and compare it to numerical simulations. We decompose the covariance matrix into the disconnected (Gaussian) part, trispectrum from the modes outside the survey (beat coupling or super-sample variance), and trispectrum from the modes inside the survey, and show how the different components contribute to the overall covariance matrix. We find the agreement with the simulations is at a 10\\% level up to $k \\sim 1 h {\\rm Mpc^{-1}}$. We show that all the connected components are dominated by the large-scale modes ($k<0.1 h {\\rm Mpc^{-1}}$), regardless of the value of the wavevectors $k,\\, k'$ of the covariance matrix, suggesting that one must be careful in applying the jackknife or bootstrap methods to the covariance matrix. We perform an eigenmode decomposition of the connected part of the covariance matrix, showing that at higher $k$ it is dominated by a single eigenmode. The full covariance matrix can be approximated as the disconnected part only, with the connected part being treated as an external nuisance parameter with a known scale dependence, and a known prior on its variance for a given survey volume. Finally, we provide a prescription for how to evaluate the covariance matrix from small box simulations without the need to simulate large volumes.

  16. Perturbative approach to covariance matrix of the matter power spectrum

    NASA Astrophysics Data System (ADS)

    Mohammed, Irshad; Seljak, Uroš; Vlah, Zvonimir

    2017-04-01

    We evaluate the covariance matrix of the matter power spectrum using perturbation theory up to dominant terms at 1-loop order and compare it to numerical simulations. We decompose the covariance matrix into the disconnected (Gaussian) part, trispectrum from the modes outside the survey (supersample variance) and trispectrum from the modes inside the survey, and show how the different components contribute to the overall covariance matrix. We find the agreement with the simulations is at a 10 per cent level up to k ∼ 1 h Mpc-1. We show that all the connected components are dominated by the large-scale modes (k < 0.1 h Mpc-1), regardless of the value of the wave vectors k, k΄ of the covariance matrix, suggesting that one must be careful in applying the jackknife or bootstrap methods to the covariance matrix. We perform an eigenmode decomposition of the connected part of the covariance matrix, showing that at higher k, it is dominated by a single eigenmode. The full covariance matrix can be approximated as the disconnected part only, with the connected part being treated as an external nuisance parameter with a known scale dependence, and a known prior on its variance for a given survey volume. Finally, we provide a prescription for how to evaluate the covariance matrix from small box simulations without the need to simulate large volumes.

  17. Mixed Mode Matrix Multiplication

    SciTech Connect

    Meng-Shiou Wu; Srinivas Aluru; Ricky A. Kendall

    2004-09-30

    In modern clustering environments where the memory hierarchy has many layers (distributed memory, shared memory layer, cache,...), an important question is how to fully utilize all available resources and identify the most dominant layer in certain computations. When combining algorithms on all layers together, what would be the best method to get the best performance out of all the resources we have? Mixed mode programming model that uses thread programming on the shared memory layer and message passing programming on the distributed memory layer is a method that many researchers are using to utilize the memory resources. In this paper, they take an algorithmic approach that uses matrix multiplication as a tool to show how cache algorithms affect the performance of both shared memory and distributed memory algorithms. They show that with good underlying cache algorithm, overall performance is stable. When underlying cache algorithm is bad, superlinear speedup may occur, and an increasing number of threads may also improve performance.

  18. Matrix membranes and integrability

    SciTech Connect

    Zachos, C.; Fairlie, D.; Curtright, T.

    1997-06-01

    This is a pedagogical digest of results reported in Curtright, Fairlie, {ampersand} Zachos 1997, and an explicit implementation of Euler`s construction for the solution of the Poisson Bracket dual Nahm equation. But it does not cover 9 and 10-dimensional systems, and subsequent progress on them Fairlie 1997. Cubic interactions are considered in 3 and 7 space dimensions, respectively, for bosonic membranes in Poisson Bracket form. Their symmetries and vacuum configurations are explored. Their associated first order equations are transformed to Nahm`s equations, and are hence seen to be integrable, for the 3-dimensional case, by virtue of the explicit Lax pair provided. Most constructions introduced also apply to matrix commutator or Moyal Bracket analogs.

  19. Hyaluronan: A Matrix Component

    NASA Astrophysics Data System (ADS)

    Rügheimer, Louise

    2008-09-01

    The glucosaminoglycan hyaluronan is a key component of the extracellular matrix. It is a large, negatively charged molecule that can act as an ion exchange reservoir for positive ions. Hyaluronan is involved in renomedullary water handling through its water-binding capacity. In the renal medulla, the main source for hyaluronan production is the renomedullary interstitial cells. Hyaluronan synthases are found in the inner part of the plasma membrane and polymerize hyaluronan chains which are extruded into the extracellular space. Hyaluronidases are a family of enzymes involved in the degradation of hyaluronan. They have a wide range of properties, including differences in size, inhibitor sensitivities, catalytic mechanisms, substrate specificities and pH optima.

  20. Light cone matrix product

    SciTech Connect

    Hastings, Matthew B

    2009-01-01

    We show how to combine the light-cone and matrix product algorithms to simulate quantum systems far from equilibrium for long times. For the case of the XXZ spin chain at {Delta} = 0.5, we simulate to a time of {approx} 22.5. While part of the long simulation time is due to the use of the light-cone method, we also describe a modification of the infinite time-evolving bond decimation algorithm with improved numerical stability, and we describe how to incorporate symmetry into this algorithm. While statistical sampling error means that we are not yet able to make a definite statement, the behavior of the simulation at long times indicates the appearance of either 'revivals' in the order parameter as predicted by Hastings and Levitov (e-print arXiv:0806.4283) or of a distinct shoulder in the decay of the order parameter.