Visualization of newt aragonitic otoconial matrices using transmission electron microscopy

NASA Technical Reports Server (NTRS)

Steyger, P. S.; Wiederhold, M. L.

1995-01-01

Otoconia are calcified protein matrices within the gravity-sensing organs of the vertebrate vestibular system. These protein matrices are thought to originate from the supporting or hair cells in the macula during development. Previous studies of mammalian calcitic, barrel-shaped otoconia revealed an organized protein matrix consisting of a thin peripheral layer, a well-defined organic core and a flocculent matrix inbetween. No studies have reported the microscopic organization of the aragonitic otoconial matrix, despite its protein characterization. Pote et al. (1993b) used densitometric methods and inferred that prismatic (aragonitic) otoconia have a peripheral protein distribution, compared to that described for the barrel-shaped, calcitic otoconia of birds, mammals, and the amphibian utricle. By using tannic acid as a negative stain, we observed three kinds of organic matrices in preparations of fixed, decalcified saccular otoconia from the adult newt: (1) fusiform shapes with a homogenous electron-dense matrix; (2) singular and multiple strands of matrix; and (3) more significantly, prismatic shapes outlined by a peripheral organic matrix. These prismatic shapes remain following removal of the gelatinous matrix, revealing an internal array of organic matter. We conclude that prismatic otoconia have a largely peripheral otoconial matrix, as inferred by densitometry.

In-depth proteomic analysis of a mollusc shell: acid-soluble and acid-insoluble matrix of the limpet Lottia gigantea

PubMed Central

2012-01-01

Background Invertebrate biominerals are characterized by their extraordinary functionality and physical properties, such as strength, stiffness and toughness that by far exceed those of the pure mineral component of such composites. This is attributed to the organic matrix, secreted by specialized cells, which pervades and envelops the mineral crystals. Despite the obvious importance of the protein fraction of the organic matrix, only few in-depth proteomic studies have been performed due to the lack of comprehensive protein sequence databases. The recent public release of the gastropod Lottia gigantea genome sequence and the associated protein sequence database provides for the first time the opportunity to do a state-of-the-art proteomic in-depth analysis of the organic matrix of a mollusc shell. Results Using three different sodium hypochlorite washing protocols before shell demineralization, a total of 569 proteins were identified in Lottia gigantea shell matrix. Of these, 311 were assembled in a consensus proteome comprising identifications contained in all proteomes irrespective of shell cleaning procedure. Some of these proteins were similar in amino acid sequence, amino acid composition, or domain structure to proteins identified previously in different bivalve or gastropod shells, such as BMSP, dermatopontin, nacrein, perlustrin, perlucin, or Pif. In addition there were dozens of previously uncharacterized proteins, many containing repeated short linear motifs or homorepeats. Such proteins may play a role in shell matrix construction or control of mineralization processes. Conclusions The organic matrix of Lottia gigantea shells is a complex mixture of proteins comprising possible homologs of some previously characterized mollusc shell proteins, but also many novel proteins with a possible function in biomineralization as framework building blocks or as regulatory components. We hope that this data set, the most comprehensive available at present, will provide a platform for the further exploration of biomineralization processes in molluscs. PMID:22540284

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

Zhu, Cheng; Tsuge, Masashi; Khriachtchev, Leonid, E-mail: leonid.khriachtchev@helsinki.fi

Experimental and theoretical studies of HXeI and HXeH molecules in Ar, Kr, and Xe matrices are presented. HXeI exhibits the H–Xe stretching bands at 1238.0 and 1239.0 cm{sup −1} in Ar and Kr matrices, respectively, that are blue-shifted from the HXeI band observed in a Xe matrix (1193 cm{sup −1}) by 45 and 46 cm{sup −1}. These shifts are larger than those observed previously for HXeCl (27 and 16 cm{sup −1}) and HXeBr (37 and 23 cm{sup −1}); thus, the matrix effect is stronger for less stable molecules. The results for HXeI are qualitatively different from all previous results onmore » noble-gas hydrides with respect to the frequency order between Ar and Kr matrices. For previously studied HXeCl, HXeBr, and HXeCCH, the H–Xe stretching frequency is reliably (by >10 cm{sup −1}) higher in an Ar matrix than in a Kr matrix. In contrast, the H–Xe stretching frequency of HXeI in an Ar matrix is slightly lower than that in a Kr matrix. HXeH absorbs in Ar and Kr matrices at 1203.2 and 1192.1 cm{sup −1} (the stronger band for a Kr matrix), respectively. These bands are blue-shifted from the stronger band of HXeH in a Xe matrix (1166 cm{sup −1}) by 37 and 26 cm{sup −1}, and this frequency order is the same as observed for HXeCl, HXeBr, and HXeCCH but different from HXeI. The present hybrid quantum-classical simulations successfully describe the main experimental findings. For HXeI in the 〈110〉 (double substitution) site, the order of the H–Xe stretching frequencies (ν(Xe) < ν(Ar) < ν(Kr)) is in accord with the experimental observations, and also the frequency shifts in Ar and Kr matrices from a Xe matrix are well predicted (30 and 34 cm{sup −1}). Both in the theory and experiment, the order of the H–Xe stretching frequencies differs from the case of HXeCl, which suggests the adequate theoretical description of the matrix effect. For HXeH in the 〈100〉 (single substitution) site, the order of the frequencies is ν(Xe) < ν(Kr) < ν(Ar), which also agrees with the experiments. The calculated frequency shifts for HXeH in Ar and Kr matrices with respect to a Xe matrix (36 and 23 cm{sup −1}) are in a good agreement with the experiments. The present calculations predict an increase of the H–Xe stretching frequencies in the noble-gas matrices with respect to vacuum.« less

Relationship between diffusivity of water molecules inside hydrating tablets and their drug release behavior elucidated by magnetic resonance imaging.

PubMed

Kikuchi, Shingo; Onuki, Yoshinori; Kuribayashi, Hideto; Takayama, Kozo

2012-01-01

We reported previously that sustained release matrix tablets showed zero-order drug release without being affected by pH change. To understand drug release mechanisms more fully, we monitored the swelling and erosion of hydrating tablets using magnetic resonance imaging (MRI). Three different types of tablets comprised of polyion complex-forming materials and a hydroxypropyl methylcellulose (HPMC) were used. Proton density- and diffusion-weighted images of the hydrating tablets were acquired at intervals. Furthermore, apparent self-diffusion coefficient maps were generated from diffusion-weighted imaging to evaluate the state of hydrating tablets. Our findings indicated that water penetration into polyion complex tablets was faster than that into HPMC matrix tablets. In polyion complex tablets, water molecules were dispersed homogeneously and their diffusivity was relatively high, whereas in HPMC matrix tablets, water molecule movement was tightly restricted within the gel. An optimal tablet formulation determined in a previous study had water molecule penetration and diffusivity properties that appeared intermediate to those of polyion complex and HPMC matrix tablets; water molecules were capable of penetrating throughout the tablets and relatively high diffusivity was similar to that in the polyion complex tablet, whereas like the HPMC matrix tablet, it was well swollen. This study succeeded in characterizing the tablet hydration process. MRI provides profound insight into the state of water molecules in hydrating tablets; thus, it is a useful tool for understanding drug release mechanisms at a molecular level.

Predicting drug-target interactions by dual-network integrated logistic matrix factorization

NASA Astrophysics Data System (ADS)

Hao, Ming; Bryant, Stephen H.; Wang, Yanli

2017-01-01

In this work, we propose a dual-network integrated logistic matrix factorization (DNILMF) algorithm to predict potential drug-target interactions (DTI). The prediction procedure consists of four steps: (1) inferring new drug/target profiles and constructing profile kernel matrix; (2) diffusing drug profile kernel matrix with drug structure kernel matrix; (3) diffusing target profile kernel matrix with target sequence kernel matrix; and (4) building DNILMF model and smoothing new drug/target predictions based on their neighbors. We compare our algorithm with the state-of-the-art method based on the benchmark dataset. Results indicate that the DNILMF algorithm outperforms the previously reported approaches in terms of AUPR (area under precision-recall curve) and AUC (area under curve of receiver operating characteristic) based on the 5 trials of 10-fold cross-validation. We conclude that the performance improvement depends on not only the proposed objective function, but also the used nonlinear diffusion technique which is important but under studied in the DTI prediction field. In addition, we also compile a new DTI dataset for increasing the diversity of currently available benchmark datasets. The top prediction results for the new dataset are confirmed by experimental studies or supported by other computational research.

Internal damping due to dislocation movements induced by thermal expansion mismatch between matrix and particles in metal matrix composites. [Al/SiC

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

Girand, C.; Lormand, G.; Fougeres, R.

In metal matrix composites (MMCs), the mechanical 1 of the reinforcement-matrix interface is an important parameter because it governs the load transfer from matrix to particles, from which the mechanical properties of these materials are derived. Therefore, it would be useful to set out an experimental method able to characterize the interface and the adjacent matrix behaviors. Thus, a study has been undertaken by means of internal damping (I.D.) measurements, which are well known to be very sensitive for studying irreversible displacements at the atomic scale. More especially, this investigation is based on the fact that, during cooling of MMC's,more » stress concentrations originating from differences in coefficients of thermal expansion (C.T.E.) of matrix and particles should induce dislocation movements in the matrix surrounding the reinforcement; that is, local microplastic strains occur. Therefore, during I.D. measurements vs temperature these movements should contribute to MMCs I.D. in a process similar to those involved around first order phase transitions in solids. The aim of this paper is to present, in the case of Al/SiC particulate composites, new developments of this approach that has previously led to promising results in the case of Al-Si alloys.« less

Power-law expansion of the Universe from the bosonic Lorentzian type IIB matrix model

NASA Astrophysics Data System (ADS)

Ito, Yuta; Nishimura, Jun; Tsuchiya, Asato

2015-11-01

Recent studies on the Lorentzian version of the type IIB matrix model show that (3+1)D expanding universe emerges dynamically from (9+1)D space-time predicted by superstring theory. Here we study a bosonic matrix model obtained by omitting the fermionic matrices. With the adopted simplification and the usage of a large-scale parallel computer, we are able to perform Monte Carlo calculations with matrix size up to N = 512, which is twenty times larger than that used previously for the studies of the original model. When the matrix size is larger than some critical value N c ≃ 110, we find that (3+1)D expanding universe emerges dynamically with a clear large- N scaling property. Furthermore, the observed increase of the spatial extent with time t at sufficiently late times is consistent with a power-law behavior t 1/2, which is reminiscent of the expanding behavior of the Friedmann-Robertson-Walker universe in the radiation dominated era. We discuss possible implications of this result on the original supersymmetric model including fermionic matrices.

Calreticulin--an endoplasmic reticulum protein with calcium-binding activity is also found in the extracellular matrix.

PubMed

Somogyi, Eszter; Petersson, Ulrika; Hultenby, Kjell; Wendel, Mikael

2003-04-01

Previous studies have reported that calreticulin (CRT), a calcium-binding and chaperoning protein, is expressed only in the endoplasmatic reticulum, nucleus and at the cell surface. In this study we clearly show that odontoblasts and predentin matrix contain CRT. To our knowledge, this is the first time CRT has been described in the extracellular matrix. The expression of CRT was studied by immunohistochemistry, ultrastructural immunocytochemistry and in situ hybridization in developing rat teeth. CRT was detected as a 59-kDa protein in rat pulp cell culture medium and dentin extracellular matrix extract by Western blotting. The presence of the protein was shown in rat odontoblasts and predentin with immunohistochemistry. At the ultrastructural level, the labeling was distributed in the rat odontoblasts, ameloblasts and predentin. Northern blotting showed the presence of CRT mRNA in rat molars, which was confirmed by in situ hybridization in odontoblasts and ameloblasts. We now present the first convincing evidence that CRT is found in extracellular matrix where it may play an important role in mineralization.

Critical speeds and forced response solutions for active magnetic bearing turbomachinery, part 2

NASA Technical Reports Server (NTRS)

Rawal, D.; Keesee, J.; Kirk, R. Gordon

1991-01-01

The need for better performance of turbomachinery with active magnetic bearings has necessitated a study of such systems for accurate prediction of their vibrational characteristics. A modification of existing transfer matrix methods for rotor analysis is presented to predict the response of rotor systems with active magnetic bearings. The position of the magnetic bearing sensors is taken into account and the effect of changing sensor position on the vibrational characteristics of the rotor system is studied. The modified algorithm is validated using a simpler Jeffcott model described previously. The effect of changing from a rotating unbalance excitation to a constant excitation in a single plane is also studied. A typical eight stage centrifugal compressor rotor is analyzed using the modified transfer matrix code. The results for a two mass Jeffcott model were presented previously. The results obtained by running this model with the transfer matrix method were compared with the results of the Jeffcott analysis for the purposes of verification. Also included are plots of amplitude versus frequency for the eight stage centrifugal compressor rotor. These plots demonstrate the significant influence that sensor location has on the amplitude and critical frequencies of the rotor system.

Nonlinear Penalized Estimation of True Q-Matrix in Cognitive Diagnostic Models

ERIC Educational Resources Information Center

Xiang, Rui

2013-01-01

A key issue of cognitive diagnostic models (CDMs) is the correct identification of Q-matrix which indicates the relationship between attributes and test items. Previous CDMs typically assumed a known Q-matrix provided by domain experts such as those who developed the questions. However, misspecifications of Q-matrix had been discovered in the past…

A review of biostratigraphic studies in the olistostrome deposits of Karangsambung Formation

NASA Astrophysics Data System (ADS)

Hendrizan, Marfasran

2018-02-01

Planktonic foraminifera is widely used for marine sediment biostratigraphy. Foraminiferal biostratigraphy of Karangsambung Formation is relatively rare to be investigated by previous researchers. A review of foraminiferal biostratigraphy is expected to be early work to perform a research about the ages of Tertiary rock formations in Karangsambung. The research area is formed by olistostrome process; a sedimentary slide deposit characterized by bodies of harder rock mixed and dispersed in a matrix. Biostratigraphic studies based on foraminifera and nannoplankton in Karangsambung Formation are still qualitative analysis using fossils biomarker. However, the age of this formation is still debatable based on foraminifera and nannofossil analysis. Two explanations of debatable ages in Karangsambung Formation that is possibly developed in Karangsambung area: firstly, Karangsambung Formation is characterized by normal sedimentation in some places and other regions such Kali Welaran and Clebok, Village as a product of olistostrome, and secondly, Karangsambung Formation is olistostrome deposit. However, micropaleontology sampling and analysis in matrix clays from olistostrome were ignored causing biostratigraphical results in those matrix clays occurred in normal sedimentation process and achieving the age of middle Eocene to Oligocene. We suppose previous authors picked samples in matrix of Karangsambung Formation from several river sections, which will make misinterpretation of the age of Karangsambung Formation. The age of middle to late Eocene probably is the dates of the older sediment that was reworked by sliding and sampling process and accumulated in Karangsambung Formation. The date of Karangsambung Fm is in Oligocene period based on a finding of several calcareous nannofossils. Detailed micropaleontological analysis of olistostrome deposits in Karangsambung Formation should be reevaluated for new finding of the accurate dating. Re-evaluation should start from detailed sedimentological mapping of Karangsambung Fm transects based on previous authors especially Kali Welaran, Jatibungkus transect and Clebok section followed by systematic sampling of normal sedimentation process from olistostrome products and matrix clays of olistostrome Karangsambung Formation. Finally, quantitative method of micropaleontological analysis can be applied to identify the age of Karangsambung Formation.

On the regularity of the covariance matrix of a discretized scalar field on the sphere

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

Bilbao-Ahedo, J.D.; Barreiro, R.B.; Herranz, D.

2017-02-01

We present a comprehensive study of the regularity of the covariance matrix of a discretized field on the sphere. In a particular situation, the rank of the matrix depends on the number of pixels, the number of spherical harmonics, the symmetries of the pixelization scheme and the presence of a mask. Taking into account the above mentioned components, we provide analytical expressions that constrain the rank of the matrix. They are obtained by expanding the determinant of the covariance matrix as a sum of determinants of matrices made up of spherical harmonics. We investigate these constraints for five different pixelizationsmore » that have been used in the context of Cosmic Microwave Background (CMB) data analysis: Cube, Icosahedron, Igloo, GLESP and HEALPix, finding that, at least in the considered cases, the HEALPix pixelization tends to provide a covariance matrix with a rank closer to the maximum expected theoretical value than the other pixelizations. The effect of the propagation of numerical errors in the regularity of the covariance matrix is also studied for different computational precisions, as well as the effect of adding a certain level of noise in order to regularize the matrix. In addition, we investigate the application of the previous results to a particular example that requires the inversion of the covariance matrix: the estimation of the CMB temperature power spectrum through the Quadratic Maximum Likelihood algorithm. Finally, some general considerations in order to achieve a regular covariance matrix are also presented.« less

Matrix viscoplasticity and its shielding by active mechanics in microtissue models: experiments and mathematical modeling

NASA Astrophysics Data System (ADS)

Liu, Alan S.; Wang, Hailong; Copeland, Craig R.; Chen, Christopher S.; Shenoy, Vivek B.; Reich, Daniel H.

2016-09-01

The biomechanical behavior of tissues under mechanical stimulation is critically important to physiological function. We report a combined experimental and modeling study of bioengineered 3D smooth muscle microtissues that reveals a previously unappreciated interaction between active cell mechanics and the viscoplastic properties of the extracellular matrix. The microtissues’ response to stretch/unstretch actuations, as probed by microcantilever force sensors, was dominated by cellular actomyosin dynamics. However, cell lysis revealed a viscoplastic response of the underlying model collagen/fibrin matrix. A model coupling Hill-type actomyosin dynamics with a plastic perfectly viscoplastic description of the matrix quantitatively accounts for the microtissue dynamics, including notably the cells’ shielding of the matrix plasticity. Stretch measurements of single cells confirmed the active cell dynamics, and were well described by a single-cell version of our model. These results reveal the need for new focus on matrix plasticity and its interactions with active cell mechanics in describing tissue dynamics.

Matrix viscoplasticity and its shielding by active mechanics in microtissue models: experiments and mathematical modeling

PubMed Central

Liu, Alan S.; Wang, Hailong; Copeland, Craig R.; Chen, Christopher S.; Shenoy, Vivek B.; Reich, Daniel H.

2016-01-01

The biomechanical behavior of tissues under mechanical stimulation is critically important to physiological function. We report a combined experimental and modeling study of bioengineered 3D smooth muscle microtissues that reveals a previously unappreciated interaction between active cell mechanics and the viscoplastic properties of the extracellular matrix. The microtissues’ response to stretch/unstretch actuations, as probed by microcantilever force sensors, was dominated by cellular actomyosin dynamics. However, cell lysis revealed a viscoplastic response of the underlying model collagen/fibrin matrix. A model coupling Hill-type actomyosin dynamics with a plastic perfectly viscoplastic description of the matrix quantitatively accounts for the microtissue dynamics, including notably the cells’ shielding of the matrix plasticity. Stretch measurements of single cells confirmed the active cell dynamics, and were well described by a single-cell version of our model. These results reveal the need for new focus on matrix plasticity and its interactions with active cell mechanics in describing tissue dynamics. PMID:27671239

Five- and six-electron harmonium atoms: Highly accurate electronic properties and their application to benchmarking of approximate 1-matrix functionals

NASA Astrophysics Data System (ADS)

Cioslowski, Jerzy; Strasburger, Krzysztof

2018-04-01

Electronic properties of several states of the five- and six-electron harmonium atoms are obtained from large-scale calculations employing explicitly correlated basis functions. The high accuracy of the computed energies (including their components), natural spinorbitals, and their occupation numbers makes them suitable for testing, calibration, and benchmarking of approximate formalisms of quantum chemistry and solid state physics. In the case of the five-electron species, the availability of the new data for a wide range of the confinement strengths ω allows for confirmation and generalization of the previously reached conclusions concerning the performance of the presently known approximations for the electron-electron repulsion energy in terms of the 1-matrix that are at heart of the density matrix functional theory (DMFT). On the other hand, the properties of the three low-lying states of the six-electron harmonium atom, computed at ω = 500 and ω = 1000, uncover deficiencies of the 1-matrix functionals not revealed by previous studies. In general, the previously published assessment of the present implementations of DMFT being of poor accuracy is found to hold. Extending the present work to harmonically confined systems with even more electrons is most likely counterproductive as the steep increase in computational cost required to maintain sufficient accuracy of the calculated properties is not expected to be matched by the benefits of additional information gathered from the resulting benchmarks.

Bovine versus Porcine Acellular Dermal Matrix: A Comparison of Mechanical Properties.

PubMed

Adelman, David M; Selber, Jesse C; Butler, Charles E

2014-05-01

Porcine and bovine acellular dermal matrices (PADM and BADM, respectively) are the most commonly used biologic meshes for ventral hernia repair. A previous study suggests a higher rate of intraoperative device failures using PADM than BADM. We hypothesize that this difference is, in part, related to intrinsic mechanical properties of the matrix substrate and source material. The following study directly compares these 2 matrices to identify any potential differences in mechanical properties that may relate to clinical outcomes. Sections of PADM (Strattice; Lifecell, Branchburg, N.J.) and BADM (SurgiMend; TEI Biosciences, Boston, Mass.) were subjected to a series of biomechanical tests, including suture retention, tear strength, and uniaxial tensile strength. Results were collected and compared statistically. In all parameters, BADM exhibited a superior mechanical strength profile compared with PADM of similar thickness. Increased BADM thickness correlated with increased mechanical strength. In suture tear-through testing with steel wire, failure of the steel wire occurred in the 4-mm-thick BADM, whereas the matrix material failed in all other thicknesses of BADM and PADM. Before implantation, BADM is inherently stronger than PADM at equivalent thicknesses and considerably stronger at increased thicknesses. These results corroborate clinical data from a previous study in which PADM was associated with a higher intraoperative device failure rate. Although numerous properties of acellular dermal matrix contribute to clinical outcomes, surgeons should consider initial mechanical strength properties when choosing acellular dermal matrices for load-bearing applications such as hernia repair.

Implementation of Fiber Substructuring Into Strain Rate Dependent Micromechanics Analysis of Polymer Matrix Composites

NASA Technical Reports Server (NTRS)

Goldberg, Robert K.

2001-01-01

A research program is in progress to develop strain rate dependent deformation and failure models for the analysis of polymer matrix composites subject to impact loads. Previously, strain rate dependent inelastic constitutive equations developed to model the polymer matrix were incorporated into a mechanics of materials based micromechanics method. In the current work, the micromechanics method is revised such that the composite unit cell is divided into a number of slices. Micromechanics equations are then developed for each slice, with laminate theory applied to determine the elastic properties, effective stresses and effective inelastic strains for the unit cell. Verification studies are conducted using two representative polymer matrix composites with a nonlinear, strain rate dependent deformation response. The computed results compare well to experimentally obtained values.

Validating internet research: a test of the psychometric equivalence of internet and in-person samples.

PubMed

Meyerson, Paul; Tryon, Warren W

2003-11-01

This study evaluated the psychometric equivalency of Web-based research. The Sexual Boredom Scale was presented via the World-Wide Web along with five additional scales used to validate it. A subset of 533 participants that matched a previously published sample (Watt & Ewing, 1996) on age, gender, and race was identified. An 8 x 8 correlation matrix from the matched Internet sample was compared via structural equation modeling with a similar 8 x 8 correlation matrix from the previously published study. The Internet and previously published samples were psychometrically equivalent. Coefficient alpha values calculated on the matched Internet sample yielded reliability coefficients almost identical to those for the previously published sample. Factors such as computer administration and uncontrollable administration settings did not appear to affect the results. Demographic data indicated an overrepresentation of males by about 6% and Caucasians by about 13% relative to the U.S. Census (2000). A total of 2,230 participants were obtained in about 8 months without remuneration. These results suggest that data collection on the Web is (1) reliable, (2) valid, (3) reasonably representative, (4) cost effective, and (5) efficient.

Formic acid dimers in a nitrogen matrix

NASA Astrophysics Data System (ADS)

Lopes, Susy; Fausto, Rui; Khriachtchev, Leonid

2018-01-01

Formic acid (HCOOH) dimers are studied by infrared spectroscopy in a nitrogen matrix and by ab initio calculations. We benefit from the use of a nitrogen matrix where the lifetime of the higher-energy (cis) conformer is very long (˜11 h vs. 7 min in an argon matrix). As a result, in a nitrogen matrix, a large proportion of the cis conformer can be produced by vibrational excitation of the lower-energy (trans) conformer. Three trans-trans, four trans-cis, and three cis-cis dimers are found in the experiments. The spectroscopic information on most of these dimers is enriched compared to the previous studies in an argon matrix. The cis-cis dimers of ordinary formic acid (without deuteration) are reported here for the first time. Several conformational processes are obtained using selective excitation by infrared light, some of them also for the first time. In particular, we report on the formation of cis-cis dimers upon vibrational excitation of trans-cis dimers. Tunneling decays of several dimers have been detected in the dark. The tunneling decay of cis-cis dimers of formic acid as well as the stabilization of cis units in cis-cis dimers is also observed for the first time.

Formic acid dimers in a nitrogen matrix.

PubMed

Lopes, Susy; Fausto, Rui; Khriachtchev, Leonid

2018-01-21

Formic acid (HCOOH) dimers are studied by infrared spectroscopy in a nitrogen matrix and by ab initio calculations. We benefit from the use of a nitrogen matrix where the lifetime of the higher-energy (cis) conformer is very long (∼11 h vs. 7 min in an argon matrix). As a result, in a nitrogen matrix, a large proportion of the cis conformer can be produced by vibrational excitation of the lower-energy (trans) conformer. Three trans-trans, four trans-cis, and three cis-cis dimers are found in the experiments. The spectroscopic information on most of these dimers is enriched compared to the previous studies in an argon matrix. The cis-cis dimers of ordinary formic acid (without deuteration) are reported here for the first time. Several conformational processes are obtained using selective excitation by infrared light, some of them also for the first time. In particular, we report on the formation of cis-cis dimers upon vibrational excitation of trans-cis dimers. Tunneling decays of several dimers have been detected in the dark. The tunneling decay of cis-cis dimers of formic acid as well as the stabilization of cis units in cis-cis dimers is also observed for the first time.

Convex Banding of the Covariance Matrix

PubMed Central

Bien, Jacob; Bunea, Florentina; Xiao, Luo

2016-01-01

We introduce a new sparse estimator of the covariance matrix for high-dimensional models in which the variables have a known ordering. Our estimator, which is the solution to a convex optimization problem, is equivalently expressed as an estimator which tapers the sample covariance matrix by a Toeplitz, sparsely-banded, data-adaptive matrix. As a result of this adaptivity, the convex banding estimator enjoys theoretical optimality properties not attained by previous banding or tapered estimators. In particular, our convex banding estimator is minimax rate adaptive in Frobenius and operator norms, up to log factors, over commonly-studied classes of covariance matrices, and over more general classes. Furthermore, it correctly recovers the bandwidth when the true covariance is exactly banded. Our convex formulation admits a simple and efficient algorithm. Empirical studies demonstrate its practical effectiveness and illustrate that our exactly-banded estimator works well even when the true covariance matrix is only close to a banded matrix, confirming our theoretical results. Our method compares favorably with all existing methods, in terms of accuracy and speed. We illustrate the practical merits of the convex banding estimator by showing that it can be used to improve the performance of discriminant analysis for classifying sound recordings. PMID:28042189

Convex Banding of the Covariance Matrix.

PubMed

Bien, Jacob; Bunea, Florentina; Xiao, Luo

2016-01-01

We introduce a new sparse estimator of the covariance matrix for high-dimensional models in which the variables have a known ordering. Our estimator, which is the solution to a convex optimization problem, is equivalently expressed as an estimator which tapers the sample covariance matrix by a Toeplitz, sparsely-banded, data-adaptive matrix. As a result of this adaptivity, the convex banding estimator enjoys theoretical optimality properties not attained by previous banding or tapered estimators. In particular, our convex banding estimator is minimax rate adaptive in Frobenius and operator norms, up to log factors, over commonly-studied classes of covariance matrices, and over more general classes. Furthermore, it correctly recovers the bandwidth when the true covariance is exactly banded. Our convex formulation admits a simple and efficient algorithm. Empirical studies demonstrate its practical effectiveness and illustrate that our exactly-banded estimator works well even when the true covariance matrix is only close to a banded matrix, confirming our theoretical results. Our method compares favorably with all existing methods, in terms of accuracy and speed. We illustrate the practical merits of the convex banding estimator by showing that it can be used to improve the performance of discriminant analysis for classifying sound recordings.

Reactive solute transport in an asymmetrical fracture-rock matrix system

NASA Astrophysics Data System (ADS)

Zhou, Renjie; Zhan, Hongbin

2018-02-01

The understanding of reactive solute transport in a single fracture-rock matrix system is the foundation of studying transport behavior in the complex fractured porous media. When transport properties are asymmetrically distributed in the adjacent rock matrixes, reactive solute transport has to be considered as a coupled three-domain problem, which is more complex than the symmetric case with identical transport properties in the adjacent rock matrixes. This study deals with the transport problem in a single fracture-rock matrix system with asymmetrical distribution of transport properties in the rock matrixes. Mathematical models are developed for such a problem under the first-type and the third-type boundary conditions to analyze the spatio-temporal concentration and mass distribution in the fracture and rock matrix with the help of Laplace transform technique and de Hoog numerical inverse Laplace algorithm. The newly acquired solutions are then tested extensively against previous analytical and numerical solutions and are proven to be robust and accurate. Furthermore, a water flushing phase is imposed on the left boundary of system after a certain time. The diffusive mass exchange along the fracture/rock matrixes interfaces and the relative masses stored in each of three domains (fracture, upper rock matrix, and lower rock matrix) after the water flushing provide great insights of transport with asymmetric distribution of transport properties. This study has the following findings: 1) Asymmetric distribution of transport properties imposes greater controls on solute transport in the rock matrixes. However, transport in the fracture is mildly influenced. 2) The mass stored in the fracture responses quickly to water flushing, while the mass stored in the rock matrix is much less sensitive to the water flushing. 3) The diffusive mass exchange during the water flushing phase has similar patterns under symmetric and asymmetric cases. 4) The characteristic distance which refers to the zero diffusion between the fracture and the rock matrix during the water flushing phase is closely associated with dispersive process in the fracture.

Field investigation into unsaturated flow and transport in a fault: Model analyses

USGS Publications Warehouse

Liu, H.-H.; Salve, R.; Wang, J.-S.; Bodvarsson, G.S.; Hudson, D.

2004-01-01

Results of a fault test performed in the unsaturated zone of Yucca Mountain, Nevada, were analyzed using a three-dimensional numerical model. The fault was explicitly represented as a discrete feature and the surrounding rock was treated as a dual-continuum (fracture-matrix) system. Model calibration against seepage and water-travel-velocity data suggests that lithophysal cavities connected to fractures can considerably enhance the effective fracture porosity and therefore retard water flow in fractures. Comparisons between simulation results and tracer concentration data also indicate that matrix diffusion is an important mechanism for solute transport in unsaturated fractured rock. We found that an increased fault-matrix and fracture-matrix interface areas were needed to match the observed tracer data, which is consistent with previous studies. The study results suggest that the current site-scale model for the unsaturated zone of Yucca Mountain may underestimate radionuclide transport time within the unsaturated zone, because an increased fracture-matrix interface area and the increased effective fracture porosity arising from lithophysal cavities are not considered in the current site-scale model. ?? 2004 Published by Elsevier B.V.

Mechanical stabilization of proteolytically degradable polyethylene glycol dimethacrylate hydrogels through peptide interaction.

PubMed

Lim, Hyun Ju; Khan, Zara; Lu, Xi; Perera, T Hiran; Wilems, Thomas S; Ravivarapu, Krishna T; Smith Callahan, Laura A

2018-04-15

Balancing enhancement of neurite extension against loss of matrix support in synthetic hydrogels containing proteolytically degradable and bioactive signaling peptides to optimize tissue formation is difficult. Using a systematic approach, polyethylene glycol hydrogels containing concurrent continuous concentration gradients of the laminin derived bioactive signaling peptide, Ile-Lys-Val-Ala-Val (IKVAV), and collagen derived matrix metalloprotease degradable peptide, GPQGIWGQ, were fabricated and characterized. During proteolytic degradation of the concentration gradient hydrogels, the IKVAV and IWGQ cleavage fragment from GPQGIWGQ were found to interact and stabilize the bulk Young's Modulus of the hydrogel. Further testing of discrete samples containing GPQGIWGQ or its cleavage fragments, GPQG and IWGQ, indicates hydrophobic interactions between the peptides are not necessary for mechanical stabilization of the hydrogel, but changes in the concentration ratio between the peptides tethered in the hydrogel and salts and ions in the swelling solution can affect the stabilization. Encapsulation of human induced pluripotent stem cell derived neural stem cells did not reduce the mechanical properties of the hydrogel over a 14 day neural differentiation culture period, and IKVAV was found to maintain concentration dependent effects on neurite extension and mRNA gene expression of neural cytoskeletal markers, similar to previous studies. As a result, this work has significant implications for the analysis of biological studies in matrices, as the material and mechanical properties of the hydrogel may be unexpectedly temporally changing during culture due to interactions between peptide signaling elements, underscoring the need for greater matrix characterization during the degradation and cell culture. Greater emulation of the native extracellular matrix is necessary for tissue formation. To achieve this, matrices are becoming more complex, often including multiple bioactive signaling elements. However, peptide signaling in polyethylene glycol matrices and amino acids interactions between peptides can affect hydrogel material and mechanical properties, but are rarely studied. The current study identifies such an interaction between laminin derived peptide, IKVAV, and collagen derived matrix metalloprotease degradable peptide, GPQGIWGQ. Previous studies using these peptides did not identify their interactions' ability to mechanically stabilize the hydrogel during degradation. This work underscores the need for greater matrix characterization and consideration of bioactive signaling element effects temporally on the matrix's material and mechanical properties, as they can contribute to cellular response. Copyright © 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Structure-function correlations in glaucoma using matrix and standard automated perimetry versus time-domain and spectral-domain OCT devices.

PubMed

Pinto, Luciano Moreira; Costa, Elaine Fiod; Melo, Luiz Alberto S; Gross, Paula Blasco; Sato, Eduardo Toshio; Almeida, Andrea Pereira; Maia, Andre; Paranhos, Augusto

2014-04-10

We examined the structure-function relationship between two perimetric tests, the frequency doubling technology (FDT) matrix and standard automated perimetry (SAP), and two optical coherence tomography (OCT) devices (time-domain and spectral-domain). This cross-sectional study included 97 eyes from 29 healthy individuals, and 68 individuals with early, moderate, or advanced primary open-angle glaucoma. The correlations between overall and sectorial parameters of retinal nerve fiber layer thickness (RNFL) measured with Stratus and Spectralis OCT, and the visual field sensitivity obtained with FDT matrix and SAP were assessed. The relationship also was evaluated using a previously described linear model. The correlation coefficients for the threshold sensitivity measured with SAP and Stratus OCT ranged from 0.44 to 0.79, and those for Spectralis OCT ranged from 0.30 to 0.75. Regarding FDT matrix, the correlation ranged from 0.40 to 0.79 with Stratus OCT and from 0.39 to 0.79 with Spectralis OCT. Stronger correlations were found in the overall measurements and the arcuate sectors for both visual fields and OCT devices. A linear relationship was observed between FDT matrix sensitivity and the OCT devices. The previously described linear model fit the data from SAP and the OCT devices well, particularly in the inferotemporal sector. The FDT matrix and SAP visual sensitivities were related strongly to the RNFL thickness measured with the Stratus and Spectralis OCT devices, particularly in the overall and arcuate sectors. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

Discrimination Power of Polynomial-Based Descriptors for Graphs by Using Functional Matrices.

PubMed

Dehmer, Matthias; Emmert-Streib, Frank; Shi, Yongtang; Stefu, Monica; Tripathi, Shailesh

2015-01-01

In this paper, we study the discrimination power of graph measures that are based on graph-theoretical matrices. The paper generalizes the work of [M. Dehmer, M. Moosbrugger. Y. Shi, Encoding structural information uniquely with polynomial-based descriptors by employing the Randić matrix, Applied Mathematics and Computation, 268(2015), 164-168]. We demonstrate that by using the new functional matrix approach, exhaustively generated graphs can be discriminated more uniquely than shown in the mentioned previous work.

Discrimination Power of Polynomial-Based Descriptors for Graphs by Using Functional Matrices

PubMed Central

Dehmer, Matthias; Emmert-Streib, Frank; Shi, Yongtang; Stefu, Monica; Tripathi, Shailesh

2015-01-01

In this paper, we study the discrimination power of graph measures that are based on graph-theoretical matrices. The paper generalizes the work of [M. Dehmer, M. Moosbrugger. Y. Shi, Encoding structural information uniquely with polynomial-based descriptors by employing the Randić matrix, Applied Mathematics and Computation, 268(2015), 164–168]. We demonstrate that by using the new functional matrix approach, exhaustively generated graphs can be discriminated more uniquely than shown in the mentioned previous work. PMID:26479495

On the development of HSCT tail sizing criteria using linear matrix inequalities

NASA Technical Reports Server (NTRS)

Kaminer, Isaac

1995-01-01

This report presents the results of a study to extend existing high speed civil transport (HSCT) tail sizing criteria using linear matrix inequalities (LMI). In particular, the effects of feedback specifications, such as MIL STD 1797 Level 1 and 2 flying qualities requirements, and actuator amplitude and rate constraints on the maximum allowable cg travel for a given set of tail sizes are considered. Results comparing previously developed industry criteria and the LMI methodology on an HSCT concept airplane are presented.

Neutrino Mixing and the Double Tetrahedral Group

NASA Astrophysics Data System (ADS)

Bentov, Yoni; Zee, A.

2013-11-01

In the spirit of a previous study of the tetrahedral group T ≃A4, we discuss a minimalist scheme to derive the neutrino mixing matrix using the double tetrahedral group T‧, the double cover of T. The new features are three distinct two-dimensional representations and complex Clebsch-Gordan coefficients, which can result in a geometric source of CP violation in the neutrino mass matrix. In an appendix, we derive explicitly the relevant group theory for the tetrahedral group T and its double cover T‧.

Electrical percolation threshold of magnetostrictive inclusions in a piezoelectric matrix under simulated sintering conditions

NASA Astrophysics Data System (ADS)

Bedard, Antoine Joseph; Barbero, Ever J.

2018-03-01

Magnetoelectric (ME) composites can be produced by embedding magnetostrictive H particles in a piezoelectric E matrix derived from a piezoelectric powder precursor. Previously, using a bi-disperse hard-shell model (Barbero and Bedard in Comput Part Mech, 2018. https://doi.org/10.1007/s40571-017-0165-4), it has been shown that the electrical percolation threshold of the conductive H phase can be increased by decreasing the piezoelectric E particle size, relative to the H phase particle size, and by increasing short-range affinity between the E and H particles. This study builds on our previous study by exploring what happens during sintering of the ME composite when either the H or E particles undergo deformation. It was found that deformation of the H particles reduces the percolation threshold, and that deformation of E particles increases inter-phase H-E mechanical coupling, thus contributing to enhancing of ME coupling.

Visualization of extracellular matrix components within sectioned Salmonella biofilms on the surface of human gallstones.

PubMed

Marshall, Joanna M; Flechtner, Alan D; La Perle, Krista M; Gunn, John S

2014-01-01

Chronic carriage of Salmonella Typhi is mediated primarily through the formation of bacterial biofilms on the surface of cholesterol gallstones. Biofilms, by definition, involve the formation of a bacterial community encased within a protective macromolecular matrix. Previous work has demonstrated the composition of the biofilm matrix to be complex and highly variable in response to altered environmental conditions. Although known to play an important role in bacterial persistence in a variety of contexts, the Salmonella biofilm matrix remains largely uncharacterized under physiological conditions. Initial attempts to study matrix components and architecture of the biofilm matrix on gallstone surfaces were hindered by the auto-fluorescence of cholesterol. In this work we describe a method for sectioning and direct visualization of extracellular matrix components of the Salmonella biofilm on the surface of human cholesterol gallstones and provide a description of the major matrix components observed therein. Confocal micrographs revealed robust biofilm formation, characterized by abundant but highly heterogeneous expression of polysaccharides such as LPS, Vi and O-antigen capsule. CsgA was not observed in the biofilm matrix and flagellar expression was tightly restricted to the biofilm-cholesterol interface. Images also revealed the presence of preexisting Enterobacteriaceae encased within the structure of the gallstone. These results demonstrate the use and feasibility of this method while highlighting the importance of studying the native architecture of the gallstone biofilm. A better understanding of the contribution of individual matrix components to the overall biofilm structure will facilitate the development of more effective and specific methods to disrupt these bacterial communities.

Novel image analysis methods for quantification of in situ 3-D tendon cell and matrix strain.

PubMed

Fung, Ashley K; Paredes, J J; Andarawis-Puri, Nelly

2018-01-23

Macroscopic tendon loads modulate the cellular microenvironment leading to biological outcomes such as degeneration or repair. Previous studies have shown that damage accumulation and the phases of tendon healing are marked by significant changes in the extracellular matrix, but it remains unknown how mechanical forces of the extracellular matrix are translated to mechanotransduction pathways that ultimately drive the biological response. Our overarching hypothesis is that the unique relationship between extracellular matrix strain and cell deformation will dictate biological outcomes, prompting the need for quantitative methods to characterize the local strain environment. While 2-D methods have successfully calculated matrix strain and cell deformation, 3-D methods are necessary to capture the increased complexity that can arise due to high levels of anisotropy and out-of-plane motion, particularly in the disorganized, highly cellular, injured state. In this study, we validated the use of digital volume correlation methods to quantify 3-D matrix strain using images of naïve tendon cells, the collagen fiber matrix, and injured tendon cells. Additionally, naïve tendon cell images were used to develop novel methods for 3-D cell deformation and 3-D cell-matrix strain, which is defined as a quantitative measure of the relationship between matrix strain and cell deformation. The results support that these methods can be used to detect strains with high accuracy and can be further extended to an in vivo setting for observing temporal changes in cell and matrix mechanics during degeneration and healing. Copyright © 2017. Published by Elsevier Ltd.

Consistent forcing scheme in the cascaded lattice Boltzmann method

NASA Astrophysics Data System (ADS)

Fei, Linlin; Luo, Kai Hong

2017-11-01

In this paper, we give an alternative derivation for the cascaded lattice Boltzmann method (CLBM) within a general multiple-relaxation-time (MRT) framework by introducing a shift matrix. When the shift matrix is a unit matrix, the CLBM degrades into an MRT LBM. Based on this, a consistent forcing scheme is developed for the CLBM. The consistency of the nonslip rule, the second-order convergence rate in space, and the property of isotropy for the consistent forcing scheme is demonstrated through numerical simulations of several canonical problems. Several existing forcing schemes previously used in the CLBM are also examined. The study clarifies the relation between MRT LBM and CLBM under a general framework.

Oxygen Diffusion and Reaction Kinetics in Continuous Fiber Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Halbig, Michael C.; Eckel, Andrew J.; Cawley, James D.

1999-01-01

Previous stressed oxidation tests of C/SiC composites at elevated temperatures (350 C to 1500 C) and sustained stresses (69 MPa and 172 MPa) have led to the development of a finite difference cracked matrix model. The times to failure in the samples suggest oxidation occurred in two kinetic regimes defined by the rate controlling mechanisms (i.e. diffusion controlled and reaction controlled kinetics). Microstructural analysis revealed preferential oxidation along as-fabricated, matrix microcracks and also suggested two regimes of oxidation kinetics dependent on the oxidation temperature. Based on experimental results, observation, and theory, a finite difference model was developed. The model simulates the diffusion of oxygen into a matrix crack bridged by carbon fibers. The model facilitates the study of the relative importance of temperature, the reaction rate constant, and the diffusion coefficient on the overall oxidation kinetics.

A group matrix representation relevant to scales of measurement of clinical disease states via stratified vectors.

PubMed

Sawamura, Jitsuki; Morishita, Shigeru; Ishigooka, Jun

2016-02-09

Previously, we applied basic group theory and related concepts to scales of measurement of clinical disease states and clinical findings (including laboratory data). To gain a more concrete comprehension, we here apply the concept of matrix representation, which was not explicitly exploited in our previous work. Starting with a set of orthonormal vectors, called the basis, an operator Rj (an N-tuple patient disease state at the j-th session) was expressed as a set of stratified vectors representing plural operations on individual components, so as to satisfy the group matrix representation. The stratified vectors containing individual unit operations were combined into one-dimensional square matrices [Rj]s. The [Rj]s meet the matrix representation of a group (ring) as a K-algebra. Using the same-sized matrix of stratified vectors, we can also express changes in the plural set of [Rj]s. The method is demonstrated on simple examples. Despite the incompleteness of our model, the group matrix representation of stratified vectors offers a formal mathematical approach to clinical medicine, aligning it with other branches of natural science.

High accuracy broadband infrared spectropolarimetry

NASA Astrophysics Data System (ADS)

Krishnaswamy, Venkataramanan

Mueller matrix spectroscopy or Spectropolarimetry combines conventional spectroscopy with polarimetry, providing more information than can be gleaned from spectroscopy alone. Experimental studies on infrared polarization properties of materials covering a broad spectral range have been scarce due to the lack of available instrumentation. This dissertation aims to fill the gap by the design, development, calibration and testing of a broadband Fourier Transform Infra-Red (FT-IR) spectropolarimeter. The instrument operates over the 3-12 mum waveband and offers better overall accuracy compared to the previous generation instruments. Accurate calibration of a broadband spectropolarimeter is a non-trivial task due to the inherent complexity of the measurement process. An improved calibration technique is proposed for the spectropolarimeter and numerical simulations are conducted to study the effectiveness of the proposed technique. Insights into the geometrical structure of the polarimetric measurement matrix is provided to aid further research towards global optimization of Mueller matrix polarimeters. A high performance infrared wire-grid polarizer is characterized using the spectropolarimeter. Mueller matrix spectrum measurements on Penicillin and pine pollen are also presented.

An immunohistochemical and ultrastructural study of the pericellular matrix of uneroded hypertrophic chondrocytes in the mandibular condyle of aged c-src-deficient mice.

PubMed

Shibata, Shunichi; Baba, Otto; Oda, Tsuyoshi; Yokohama-Tamaki, Tamaki; Qin, Chunlin; Butler, William T; Sakakura, Yasunori; Takano, Yoshiro

2008-03-01

Previous studies indicate that hypertrophic chondrocytes can transdifferentiate or dedifferentiate and redifferentiate into bone cells during the endochondral bone formation. Mandibular condyle in aged c-src-deficient mice has incremental line-like striations consisting of cartilaginous and non-cartilaginous layers, and the former contains intact hypertrophic chondrocytes in uneroded lacunae. The purpose of this study is to determine the phenotype changes of uneroded hypertrophic chondrocytes. Immunohistochemical and ultrastructural examinations of the pericellular matrix of hypertrophic chondrocytes in the upper, middle, and lower regions of the mandibular condyle were conducted in aged c-src-deficient mice, using several antibodies of cartilage/bone marker proteins. Co-localisation of aggrecan, type I collagen, and dentin matrix protein-1 (DMP-1) or matrix extracellular phosphoprotein (MEPE) was detected in the pericellular matrix of the middle region. Ultrastructurally, granular substances in the pericellular matrix of the middle region were the remains of upper region chondrocytes, which were mixed with thick collagen fibrils. In the lower region, the width of the pericellular matrix and the amount of collagen fibrils were increased. Versican, type I collagen, DMP-1, and MEPE were detected in the osteocyte lacunae. Additionally, DMP-1 and MEPE were detected in the pericellular matrix of uneroded hypertrophic chondrocytes located in the lower, peripheral region of the mandibular condyle in younger c-src-deficient mice, but not in the aged wild-type mice. These results indicate that long-term survived, uneroded hypertrophic chondrocytes, at least in a part, acquire osteocytic characteristics.

Micromechanical Modeling of Woven Metal Matrix Composites

NASA Technical Reports Server (NTRS)

Bednarcyk, Brett A.; Pindera, Marek-Jerzy

1997-01-01

This report presents the results of an extensive micromechanical modeling effort for woven metal matrix composites. The model is employed to predict the mechanical response of 8-harness (8H) satin weave carbon/copper (C/Cu) composites. Experimental mechanical results for this novel high thermal conductivity material were recently reported by Bednarcyk et al. along with preliminary model results. The micromechanics model developed herein is based on an embedded approach. A micromechanics model for the local (micro-scale) behavior of the woven composite, the original method of cells (Aboudi), is embedded in a global (macro-scale) micromechanics model (the three-dimensional generalized method of cells (GMC-3D) (Aboudi). This approach allows representation of true repeating unit cells for woven metal matrix composites via GMC-3D, and representation of local effects, such as matrix plasticity, yarn porosity, and imperfect fiber-matrix bonding. In addition, the equations of GMC-3D were reformulated to significantly reduce the number of unknown quantities that characterize the deformation fields at the microlevel in order to make possible the analysis of actual microstructures of woven composites. The resulting micromechanical model (WCGMC) provides an intermediate level of geometric representation, versatility, and computational efficiency with respect to previous analytical and numerical models for woven composites, but surpasses all previous modeling work by allowing the mechanical response of a woven metal matrix composite, with an elastoplastic matrix, to be examined for the first time. WCGMC is employed to examine the effects of composite microstructure, porosity, residual stresses, and imperfect fiber-matrix bonding on the predicted mechanical response of 8H satin C/Cu. The previously reported experimental results are summarized, and the model predictions are compared to monotonic and cyclic tensile and shear test data. By considering appropriate levels of porosity, residual stresses, and imperfect fiber-matrix debonding, reasonably good qualitative and quantitative correlation is achieved between model and experiment.

The G matrix under fluctuating correlational mutation and selection.

PubMed

Revell, Liam J

2007-08-01

Theoretical quantitative genetics provides a framework for reconstructing past selection and predicting future patterns of phenotypic differentiation. However, the usefulness of the equations of quantitative genetics for evolutionary inference relies on the evolutionary stability of the additive genetic variance-covariance matrix (G matrix). A fruitful new approach for exploring the evolutionary dynamics of G involves the use of individual-based computer simulations. Previous studies have focused on the evolution of the eigenstructure of G. An alternative approach employed in this paper uses the multivariate response-to-selection equation to evaluate the stability of G. In this approach, I measure similarity by the correlation between response-to-selection vectors due to random selection gradients. I analyze the dynamics of G under several conditions of correlational mutation and selection. As found in a previous study, the eigenstructure of G is stabilized by correlational mutation and selection. However, over broad conditions, instability of G did not result in a decreased consistency of the response to selection. I also analyze the stability of G when the correlation coefficients of correlational mutation and selection and the effective population size change through time. To my knowledge, no prior study has used computer simulations to investigate the stability of G when correlational mutation and selection fluctuate. Under these conditions, the eigenstructure of G is unstable under some simulation conditions. Different results are obtained if G matrix stability is assessed by eigenanalysis or by the response to random selection gradients. In this case, the response to selection is most consistent when certain aspects of the eigenstructure of G are least stable and vice versa.

Simple and practical approach for computing the ray Hessian matrix in geometrical optics.

PubMed

Lin, Psang Dain

2018-02-01

A method is proposed for simplifying the computation of the ray Hessian matrix in geometrical optics by replacing the angular variables in the system variable vector with their equivalent cosine and sine functions. The variable vector of a boundary surface is similarly defined in such a way as to exclude any angular variables. It is shown that the proposed formulations reduce the computation time of the Hessian matrix by around 10 times compared to the previous method reported by the current group in Advanced Geometrical Optics (2016). Notably, the method proposed in this study involves only polynomial differentiation, i.e., trigonometric function calls are not required. As a consequence, the computation complexity is significantly reduced. Five illustrative examples are given. The first three examples show that the proposed method is applicable to the determination of the Hessian matrix for any pose matrix, irrespective of the order in which the rotation and translation motions are specified. The last two examples demonstrate the use of the proposed Hessian matrix in determining the axial and lateral chromatic aberrations of a typical optical system.

Extracellular Protease Inhibition Alters the Phenotype of Chondrogenically Differentiating Human Mesenchymal Stem Cells (MSCs) in 3D Collagen Microspheres.

PubMed

Han, Sejin; Li, Yuk Yin; Chan, Barbara Pui

2016-01-01

Matrix remodeling of cells is highly regulated by proteases and their inhibitors. Nevertheless, how would the chondrogenesis of mesenchymal stem cells (MSCs) be affected, when the balance of the matrix remodeling is disturbed by inhibiting matrix proteases, is incompletely known. Using a previously developed collagen microencapsulation platform, we investigated whether exposing chondrogenically differentiating MSCs to intracellular and extracellular protease inhibitors will affect the extracellular matrix remodeling and hence the outcomes of chondrogenesis. Results showed that inhibition of matrix proteases particularly the extracellular ones favors the phenotype of fibrocartilage rather than hyaline cartilage in chondrogenically differentiating hMSCs by upregulating type I collagen protein deposition and type II collagen gene expression without significantly altering the hypertrophic markers at gene level. This study suggests the potential of manipulating extracellular proteases to alter the outcomes of hMSC chondrogenesis, contributing to future development of differentiation protocols for fibrocartilage tissues for intervertebral disc and meniscus tissue engineering.

Extracellular Protease Inhibition Alters the Phenotype of Chondrogenically Differentiating Human Mesenchymal Stem Cells (MSCs) in 3D Collagen Microspheres

PubMed Central

Han, Sejin; Li, Yuk Yin; Chan, Barbara Pui

2016-01-01

Matrix remodeling of cells is highly regulated by proteases and their inhibitors. Nevertheless, how would the chondrogenesis of mesenchymal stem cells (MSCs) be affected, when the balance of the matrix remodeling is disturbed by inhibiting matrix proteases, is incompletely known. Using a previously developed collagen microencapsulation platform, we investigated whether exposing chondrogenically differentiating MSCs to intracellular and extracellular protease inhibitors will affect the extracellular matrix remodeling and hence the outcomes of chondrogenesis. Results showed that inhibition of matrix proteases particularly the extracellular ones favors the phenotype of fibrocartilage rather than hyaline cartilage in chondrogenically differentiating hMSCs by upregulating type I collagen protein deposition and type II collagen gene expression without significantly altering the hypertrophic markers at gene level. This study suggests the potential of manipulating extracellular proteases to alter the outcomes of hMSC chondrogenesis, contributing to future development of differentiation protocols for fibrocartilage tissues for intervertebral disc and meniscus tissue engineering. PMID:26760956

Managing healthcare information: analyzing trust.

PubMed

Söderström, Eva; Eriksson, Nomie; Åhlfeldt, Rose-Mharie

2016-08-08

Purpose - The purpose of this paper is to analyze two case studies with a trust matrix tool, to identify trust issues related to electronic health records. Design/methodology/approach - A qualitative research approach is applied using two case studies. The data analysis of these studies generated a problem list, which was mapped to a trust matrix. Findings - Results demonstrate flaws in current practices and point to achieving balance between organizational, person and technology trust perspectives. The analysis revealed three challenge areas, to: achieve higher trust in patient-focussed healthcare; improve communication between patients and healthcare professionals; and establish clear terminology. By taking trust into account, a more holistic perspective on healthcare can be achieved, where trust can be obtained and optimized. Research limitations/implications - A trust matrix is tested and shown to identify trust problems on different levels and relating to trusting beliefs. Future research should elaborate and more fully address issues within three identified challenge areas. Practical implications - The trust matrix's usefulness as a tool for organizations to analyze trust problems and issues is demonstrated. Originality/value - Healthcare trust issues are captured to a greater extent and from previously unchartered perspectives.

Not All Inner Ears are the Same: Otolith Matrix Proteins in the Inner Ear of Sub-Adult Cichlid Fish, Oreochromis Mossambicus, Reveal Insights Into the Biomineralization Process.

PubMed

Weigele, Jochen; Franz-Odendaal, Tamara A; Hilbig, Reinhard

2016-02-01

The fish ear stones (otoliths) consist mainly of calcium carbonate and have lower amounts of a proteinous matrix. This matrix consists of macromolecules, which directly control the biomineralization process. We analyzed the composition of this proteinous matrix by mass spectrometry in a shotgun approach. For this purpose, an enhanced protein purification technique was developed that excludes any potential contamination of proteins from body fluids. Using this method we identified eight proteins in the inner ear of Oreochromis mossambicus. These include the common otolith matrix proteins (OMP-1, otolin-1, neuroserpin, SPARC and otoconin), and three proteins (alpha tectorin, otogelin and transferrin) not previously localized to the otoliths. Moreover, we were able to exclude the occurrence of two matrix proteins (starmaker and pre-cerebellin-like protein) known from other fish species. In further analyses, we show that the absence of the OMP starmaker corresponds to calcitic otoliths and that pre-cerebellin-like protein is not present at any stage during the development of the otoliths of the inner ear. This study shows O. mossambicus does not have all of the known otolith proteins indicating that the matrix proteins in the inner ear of fish are not the same across species. Further functional studies of the novel proteins we identified during otolith development are required. © 2015 Wiley Periodicals, Inc.

Sparse Matrix for ECG Identification with Two-Lead Features.

PubMed

Tseng, Kuo-Kun; Luo, Jiao; Hegarty, Robert; Wang, Wenmin; Haiting, Dong

2015-01-01

Electrocardiograph (ECG) human identification has the potential to improve biometric security. However, improvements in ECG identification and feature extraction are required. Previous work has focused on single lead ECG signals. Our work proposes a new algorithm for human identification by mapping two-lead ECG signals onto a two-dimensional matrix then employing a sparse matrix method to process the matrix. And that is the first application of sparse matrix techniques for ECG identification. Moreover, the results of our experiments demonstrate the benefits of our approach over existing methods.

STUDIES ON CARTILAGE

PubMed Central

Sheldon, Huntington; Robinson, Robert A.

1960-01-01

Electron microscope observations on rabbit ear cartilage following the administration of papain show that both the elastic component of the matrix and the amorphous material disappear leaving a matrix which consists of delicate fibrils which are presumed to be collagen. This unmasking of fibrils coincides with the appearance of an abnormal component in the electrophoretic pattern of the rabbit's serum. The chondrocytes show vacuoles in their cytoplasm which appear at the same time that the cells appear crenated in the light microscope. A ruffly appearance of the cell surface membrane coincides with this vacuolization, and vacuoles often appear open and in continuity with the extracellular space. The resurgence of the rabbit ear is accompanied by a reconstitution of both the amorphous material and the elastic component of the matrix. During this period numerous dilated cisternae of the endoplasmic reticulum which contain a moderately dense material are present in the chondrocyte cytoplasm. We have been unable to demonstrate a direct relationship between the elastic component of the matrix and a particular component of the chondrocyte cytoplasm, but it is clear that changes occur in the cartilage cell cytoplasm during both the depletion and reconstitution of the matrix. Previous studies on the effect of papain on elastic tissue are noted and the possible relationships between changes in the cells and matrix of this elastic cartilage are discussed. PMID:19866569

Novel Entries in a Fungal Biofilm Matrix Encyclopedia

PubMed Central

Zarnowski, Robert; Westler, William M.; Lacmbouh, Ghislain Ade; Marita, Jane M.; Bothe, Jameson R.; Bernhardt, Jörg; Lounes-Hadj Sahraoui, Anissa; Fontaine, Joël; Sanchez, Hiram; Hatfield, Ronald D.; Ntambi, James M.; Nett, Jeniel E.; Mitchell, Aaron P.

2014-01-01

ABSTRACT Virulence of Candida is linked with its ability to form biofilms. Once established, biofilm infections are nearly impossible to eradicate. Biofilm cells live immersed in a self-produced matrix, a blend of extracellular biopolymers, many of which are uncharacterized. In this study, we provide a comprehensive analysis of the matrix manufactured by Candida albicans both in vitro and in a clinical niche animal model. We further explore the function of matrix components, including the impact on drug resistance. We uncovered components from each of the macromolecular classes (55% protein, 25% carbohydrate, 15% lipid, and 5% nucleic acid) in the C. albicans biofilm matrix. Three individual polysaccharides were identified and were suggested to interact physically. Surprisingly, a previously identified polysaccharide of functional importance, β-1,3-glucan, comprised only a small portion of the total matrix carbohydrate. Newly described, more abundant polysaccharides included α-1,2 branched α-1,6-mannans (87%) associated with unbranched β-1,6-glucans (13%) in an apparent mannan-glucan complex (MGCx). Functional matrix proteomic analysis revealed 458 distinct activities. The matrix lipids consisted of neutral glycerolipids (89.1%), polar glycerolipids (10.4%), and sphingolipids (0.5%). Examination of matrix nucleic acid identified DNA, primarily noncoding sequences. Several of the in vitro matrix components, including proteins and each of the polysaccharides, were also present in the matrix of a clinically relevant in vivo biofilm. Nuclear magnetic resonance (NMR) analysis demonstrated interaction of aggregate matrix with the antifungal fluconazole, consistent with a role in drug impedance and contribution of multiple matrix components. PMID:25096878

Investigations of Some Liquid Matrixes for Analyte Quantification by MALDI

NASA Astrophysics Data System (ADS)

Moon, Jeong Hee; Park, Kyung Man; Ahn, Sung Hee; Lee, Seong Hoon; Kim, Myung Soo

2015-06-01

Sample inhomogeneity is one of the obstacles preventing the generation of reproducible mass spectra by MALDI and to their use for the purpose of analyte quantification. As a potential solution to this problem, we investigated MALDI with some liquid matrixes prepared by nonstoichiometric mixing of acids and bases. Out of 27 combinations of acids and bases, liquid matrixes could be produced from seven. When the overall spectral features were considered, two liquid matrixes using α-cyano-4-hydroxycinnamic acid as the acid and 3-aminoquinoline and N,N-diethylaniline as bases were the best choices. In our previous study of MALDI with solid matrixes, we found that three requirements had to be met for the generation of reproducible spectra and for analyte quantification: (1) controlling the temperature by fixing the total ion count, (2) plotting the analyte-to-matrix ion ratio versus the analyte concentration as the calibration curve, and (3) keeping the matrix suppression below a critical value. We found that the same requirements had to be met in MALDI with liquid matrixes as well. In particular, although the liquid matrixes tested here were homogeneous, they failed to display spot-to-spot spectral reproducibility unless the first requirement above was met. We also found that analyte-derived ions could not be produced efficiently by MALDI with the above liquid matrixes unless the analyte was sufficiently basic. In this sense, MALDI processes with solid and liquid matrixes should be regarded as complementary techniques rather than as competing ones.

Investigations of Some Liquid Matrixes for Analyte Quantification by MALDI.

PubMed

Moon, Jeong Hee; Park, Kyung Man; Ahn, Sung Hee; Lee, Seong Hoon; Kim, Myung Soo

2015-10-01

Sample inhomogeneity is one of the obstacles preventing the generation of reproducible mass spectra by MALDI and to their use for the purpose of analyte quantification. As a potential solution to this problem, we investigated MALDI with some liquid matrixes prepared by nonstoichiometric mixing of acids and bases. Out of 27 combinations of acids and bases, liquid matrixes could be produced from seven. When the overall spectral features were considered, two liquid matrixes using α-cyano-4-hydroxycinnamic acid as the acid and 3-aminoquinoline and N,N-diethylaniline as bases were the best choices. In our previous study of MALDI with solid matrixes, we found that three requirements had to be met for the generation of reproducible spectra and for analyte quantification: (1) controlling the temperature by fixing the total ion count, (2) plotting the analyte-to-matrix ion ratio versus the analyte concentration as the calibration curve, and (3) keeping the matrix suppression below a critical value. We found that the same requirements had to be met in MALDI with liquid matrixes as well. In particular, although the liquid matrixes tested here were homogeneous, they failed to display spot-to-spot spectral reproducibility unless the first requirement above was met. We also found that analyte-derived ions could not be produced efficiently by MALDI with the above liquid matrixes unless the analyte was sufficiently basic. In this sense, MALDI processes with solid and liquid matrixes should be regarded as complementary techniques rather than as competing ones.

The ultra-structural organization of the elastic network in the intra- and inter-lamellar matrix of the intervertebral disc.

PubMed

Tavakoli, J; Elliott, D M; Costi, J J

2017-08-01

The inter-lamellar matrix (ILM)-located between adjacent lamellae of the annulus fibrosus-consists of a complex structure of elastic fibers, while elastic fibers of the intra-lamellar region are aligned predominantly parallel to the collagen fibers. The organization of elastic fibers under low magnification, in both inter- and intra-lamellar regions, was studied by light microscopic analysis of histologically prepared samples; however, little is known about their ultrastructure. An ultrastructural visualization of elastic fibers in the inter-lamellar matrix is crucial for describing their contribution to structural integrity, as well as mechanical properties of the annulus fibrosus. The aims of this study were twofold: first, to present an ultrastructural analysis of the elastic fiber network in the ILM and intra-lamellar region, including cross section (CS) and in-plane (IP) lamellae, of the AF using Scanning Electron Microscopy (SEM) and second, to -compare the elastic fiber orientation between the ILM and intra-lamellar region. Four samples (lumbar sheep discs) from adjacent sections (30μm thickness) of anterior annulus were partially digested by a developed NaOH-sonication method for visualization of elastic fibers by SEM. Elastic fiber orientation and distribution were quantified relative to the tangential to circumferential reference axis. Visualization of the ILM under high magnification revealed a dense network of elastic fibers that has not been previously described. Within the ILM, elastic fibers form a complex network, consisting of different size and shape fibers, which differed to those located in the intra-lamellar region. For both regions, the majority of fibers were oriented near 0° with respect to tangential to circumferential (TCD) direction and two minor symmetrical orientations of approximately±45°. Statistically, the orientation of elastic fibers between the ILM and intra-lamellar region was not different (p=0.171). The present study used extracellular matrix partial digestion to address significant gaps in understanding of disc microstructure and will contribute to multidisciplinary ultrastructure-function studies. Visualization of the intra-lamellar matrix under high magnification revealed a dense network of elastic fibers that has not been previously described. The present study used extracellular matrix partial digestion to address significant gaps in understanding of disc microstructure and will contribute to multidisciplinary ultrastructure-function studies. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Information matrix estimation procedures for cognitive diagnostic models.

PubMed

Liu, Yanlou; Xin, Tao; Andersson, Björn; Tian, Wei

2018-03-06

Two new methods to estimate the asymptotic covariance matrix for marginal maximum likelihood estimation of cognitive diagnosis models (CDMs), the inverse of the observed information matrix and the sandwich-type estimator, are introduced. Unlike several previous covariance matrix estimators, the new methods take into account both the item and structural parameters. The relationships between the observed information matrix, the empirical cross-product information matrix, the sandwich-type covariance matrix and the two approaches proposed by de la Torre (2009, J. Educ. Behav. Stat., 34, 115) are discussed. Simulation results show that, for a correctly specified CDM and Q-matrix or with a slightly misspecified probability model, the observed information matrix and the sandwich-type covariance matrix exhibit good performance with respect to providing consistent standard errors of item parameter estimates. However, with substantial model misspecification only the sandwich-type covariance matrix exhibits robust performance. © 2018 The British Psychological Society.

Salient Object Detection via Structured Matrix Decomposition.

PubMed

Peng, Houwen; Li, Bing; Ling, Haibin; Hu, Weiming; Xiong, Weihua; Maybank, Stephen J

2016-05-04

Low-rank recovery models have shown potential for salient object detection, where a matrix is decomposed into a low-rank matrix representing image background and a sparse matrix identifying salient objects. Two deficiencies, however, still exist. First, previous work typically assumes the elements in the sparse matrix are mutually independent, ignoring the spatial and pattern relations of image regions. Second, when the low-rank and sparse matrices are relatively coherent, e.g., when there are similarities between the salient objects and background or when the background is complicated, it is difficult for previous models to disentangle them. To address these problems, we propose a novel structured matrix decomposition model with two structural regularizations: (1) a tree-structured sparsity-inducing regularization that captures the image structure and enforces patches from the same object to have similar saliency values, and (2) a Laplacian regularization that enlarges the gaps between salient objects and the background in feature space. Furthermore, high-level priors are integrated to guide the matrix decomposition and boost the detection. We evaluate our model for salient object detection on five challenging datasets including single object, multiple objects and complex scene images, and show competitive results as compared with 24 state-of-the-art methods in terms of seven performance metrics.

Isotropic matrix elements of the collision integral for the Boltzmann equation

NASA Astrophysics Data System (ADS)

Ender, I. A.; Bakaleinikov, L. A.; Flegontova, E. Yu.; Gerasimenko, A. B.

2017-09-01

We have proposed an algorithm for constructing matrix elements of the collision integral for the nonlinear Boltzmann equation isotropic in velocities. These matrix elements have been used to start the recurrent procedure for calculating matrix elements of the velocity-nonisotropic collision integral described in our previous publication. In addition, isotropic matrix elements are of independent interest for calculating isotropic relaxation in a number of physical kinetics problems. It has been shown that the coefficients of expansion of isotropic matrix elements in Ω integrals are connected by the recurrent relations that make it possible to construct the procedure of their sequential determination.

Temperature profile and equipartition law in a Langevin harmonic chain

NASA Astrophysics Data System (ADS)

Kim, Sangrak

2017-09-01

Temperature profile in a Langevin harmonic chain is explicitly derived and the validity of the equipartition law is checked. First, we point out that the temperature profile in previous studies does not agree with the equipartition law: In thermal equilibrium, the temperature profile deviates from the same temperature distribution against the equipartition law, particularly at the ends of the chain. The matrix connecting temperatures of the heat reservoirs and the temperatures of the harmonic oscillators turns out to be a probability matrix. By explicitly calculating the power spectrum of the probability matrix, we will show that the discrepancy comes from the neglect of the power spectrum in higher frequency ω, which is in decay mode, and related with the imaginary number of wave number q.

The Effect of Oral Vaccination with Mycobacterium bovis BCG on the Development of Tuberculosis in Captive European Badgers (Meles meles).

PubMed

Chambers, Mark A; Aldwell, Frank; Williams, Gareth A; Palmer, Si; Gowtage, Sonya; Ashford, Roland; Dalley, Deanna J; Davé, Dipesh; Weyer, Ute; Salguero, Francisco J; Nunez, Alejandro; Nadian, Allan K; Crawshaw, Timothy; Corner, Leigh A L; Lesellier, Sandrine

2017-01-01

The European badger ( Meles meles ) is a reservoir host of Mycobacterium bovis and responsible for a proportion of the tuberculosis (TB) cases seen in cattle in the United Kingdom and Republic of Ireland. An injectable preparation of the bacillus Calmette-Guérin (BCG) vaccine is licensed for use in badgers in the UK and its use forms part of the bovine TB eradication plans of England and Wales. However, there are practical limitations to the widespread application of an injectable vaccine for badgers and a research priority is the development of an oral vaccine deliverable to badgers in bait. Previous studies reported the successful vaccination of badgers with oral preparations of 10 8 colony forming units (CFU) of both Pasteur and Danish strains of BCG contained within a lipid matrix composed of triglycerides of fatty acids. Protection against TB in these studies was expressed as a reduction in the number and apparent progression of visible lesions, and reductions in the bacterial load and dissemination of infection. To reduce the cost of an oral vaccine and reduce the potential for environmental contamination with BCG, it is necessary to define the minimal efficacious dose of oral BCG for badgers. The objectives of the two studies reported here were to compare the efficacy of BCG Danish strain in a lipid matrix with unformulated BCG given orally, and to evaluate the efficacy of BCG Danish in a lipid matrix at a 10-fold lower dose than previously evaluated in badgers. In the first study, both BCG unformulated and in a lipid matrix reduced the number and apparent progression of visible lesions and the dissemination of infection from the lung. In the second study, vaccination with BCG in the lipid matrix at a 10-fold lower dose produced a similar outcome, but with greater intra-group variability than seen with the higher dose in the first study. Further research is needed before we are able to recommend a final dose of BCG for oral vaccination of badgers against TB or to know whether oral vaccination of wild badgers with BCG will significantly reduce transmission of the disease.

The Effect of Oral Vaccination with Mycobacterium bovis BCG on the Development of Tuberculosis in Captive European Badgers (Meles meles)

PubMed Central

Chambers, Mark A.; Aldwell, Frank; Williams, Gareth A.; Palmer, Si; Gowtage, Sonya; Ashford, Roland; Dalley, Deanna J.; Davé, Dipesh; Weyer, Ute; Salguero, Francisco J.; Nunez, Alejandro; Nadian, Allan K.; Crawshaw, Timothy; Corner, Leigh A. L.; Lesellier, Sandrine

2017-01-01

The European badger (Meles meles) is a reservoir host of Mycobacterium bovis and responsible for a proportion of the tuberculosis (TB) cases seen in cattle in the United Kingdom and Republic of Ireland. An injectable preparation of the bacillus Calmette-Guérin (BCG) vaccine is licensed for use in badgers in the UK and its use forms part of the bovine TB eradication plans of England and Wales. However, there are practical limitations to the widespread application of an injectable vaccine for badgers and a research priority is the development of an oral vaccine deliverable to badgers in bait. Previous studies reported the successful vaccination of badgers with oral preparations of 108 colony forming units (CFU) of both Pasteur and Danish strains of BCG contained within a lipid matrix composed of triglycerides of fatty acids. Protection against TB in these studies was expressed as a reduction in the number and apparent progression of visible lesions, and reductions in the bacterial load and dissemination of infection. To reduce the cost of an oral vaccine and reduce the potential for environmental contamination with BCG, it is necessary to define the minimal efficacious dose of oral BCG for badgers. The objectives of the two studies reported here were to compare the efficacy of BCG Danish strain in a lipid matrix with unformulated BCG given orally, and to evaluate the efficacy of BCG Danish in a lipid matrix at a 10-fold lower dose than previously evaluated in badgers. In the first study, both BCG unformulated and in a lipid matrix reduced the number and apparent progression of visible lesions and the dissemination of infection from the lung. In the second study, vaccination with BCG in the lipid matrix at a 10-fold lower dose produced a similar outcome, but with greater intra-group variability than seen with the higher dose in the first study. Further research is needed before we are able to recommend a final dose of BCG for oral vaccination of badgers against TB or to know whether oral vaccination of wild badgers with BCG will significantly reduce transmission of the disease. PMID:28174695

Linear scaling computation of the Fock matrix. II. Rigorous bounds on exchange integrals and incremental Fock build

NASA Astrophysics Data System (ADS)

Schwegler, Eric; Challacombe, Matt; Head-Gordon, Martin

1997-06-01

A new linear scaling method for computation of the Cartesian Gaussian-based Hartree-Fock exchange matrix is described, which employs a method numerically equivalent to standard direct SCF, and which does not enforce locality of the density matrix. With a previously described method for computing the Coulomb matrix [J. Chem. Phys. 106, 5526 (1997)], linear scaling incremental Fock builds are demonstrated for the first time. Microhartree accuracy and linear scaling are achieved for restricted Hartree-Fock calculations on sequences of water clusters and polyglycine α-helices with the 3-21G and 6-31G basis sets. Eightfold speedups are found relative to our previous method. For systems with a small ionization potential, such as graphitic sheets, the method naturally reverts to the expected quadratic behavior. Also, benchmark 3-21G calculations attaining microhartree accuracy are reported for the P53 tetramerization monomer involving 698 atoms and 3836 basis functions.

The impact of initialization procedures on unsupervised unmixing of hyperspectral imagery using the constrained positive matrix factorization

NASA Astrophysics Data System (ADS)

Masalmah, Yahya M.; Vélez-Reyes, Miguel

2007-04-01

The authors proposed in previous papers the use of the constrained Positive Matrix Factorization (cPMF) to perform unsupervised unmixing of hyperspectral imagery. Two iterative algorithms were proposed to compute the cPMF based on the Gauss-Seidel and penalty approaches to solve optimization problems. Results presented in previous papers have shown the potential of the proposed method to perform unsupervised unmixing in HYPERION and AVIRIS imagery. The performance of iterative methods is highly dependent on the initialization scheme. Good initialization schemes can improve convergence speed, whether or not a global minimum is found, and whether or not spectra with physical relevance are retrieved as endmembers. In this paper, different initializations using random selection, longest norm pixels, and standard endmembers selection routines are studied and compared using simulated and real data.

Google matrix of Twitter

NASA Astrophysics Data System (ADS)

Frahm, K. M.; Shepelyansky, D. L.

2012-10-01

We construct the Google matrix of the entire Twitter network, dated by July 2009, and analyze its spectrum and eigenstate properties including the PageRank and CheiRank vectors and 2DRanking of all nodes. Our studies show much stronger inter-connectivity between top PageRank nodes for the Twitter network compared to the networks of Wikipedia and British Universities studied previously. Our analysis allows to locate the top Twitter users which control the information flow on the network. We argue that this small fraction of the whole number of users, which can be viewed as the social network elite, plays the dominant role in the process of opinion formation on the network.

Evolutions of fluctuation modes and inner structures of global stock markets

NASA Astrophysics Data System (ADS)

Yan, Yan; Wang, Lei; Liu, Maoxin; Chen, Xiaosong

2016-09-01

The paper uses empirical data, including 42 globally main stock indices in the period 1996-2014, to systematically study the evolution of fluctuation modes and inner structures of global stock markets. The data are large in scale considering both time and space. A covariance matrix-based principle fluctuation mode analysis (PFMA) is used to explore the properties of the global stock markets. It has been ignored by previous studies that covariance matrix is more suitable than the correlation matrix to be the basis of PFMA. It is found that the principle fluctuation modes of global stock markets are in the same directions, and global stock markets are divided into three clusters, which are found to be closely related to the countries’ locations with exceptions of China, Russia and Czech Republic. A time-stable correlation network constructing method is proposed to solve the problem of high-level statistical uncertainty when the estimated periods are very short, and the complex dynamic network (CDN) is constructed to investigate the evolution of inner structures. The results show when the clusters emerge and how long the clusters exist. When the 2008 financial crisis broke out, the indices form one cluster. After these crises, only the European cluster still exists. These findings complement the previous studies, and can help investors and regulators to understand the global stock markets.

Round-robin study of arsenic implant dose measurement in silicon by SIMS

NASA Astrophysics Data System (ADS)

Simons, D.; Kim, K.; Benbalagh, R.; Bennett, J.; Chew, A.; Gehre, D.; Hasegawa, T.; Hitzman, C.; Ko, J.; Lindstrom, R.; MacDonald, B.; Magee, C.; Montgomery, N.; Peres, P.; Ronsheim, P.; Yoshikawa, S.; Schuhmacher, M.; Stockwell, W.; Sykes, D.; Tomita, M.; Toujou, F.; Won, J.

2006-07-01

An international round-robin study was undertaken under the auspices of ISO TC201/SC6 to determine the best analytical conditions and the level of interlaboratory agreement for the determination of the implantation dose of arsenic in silicon by secondary ion mass spectrometry (SIMS). Fifteen SIMS laboratories, as well as two laboratories that performed low energy electron-induced X-ray emission spectrometry (LEXES) and one that made measurements by instrumental neutron activation analysis (INAA) were asked to determine the implanted arsenic doses in three unknown samples using as a comparator NIST Standard Reference Material ® 2134. The use of a common reference material by all laboratories resulted in better interlaboratory agreement than was seen in a previous round-robin that lacked a common comparator. The relative standard deviation among laboratories was less than 4% for the medium-dose sample, but several percent larger for the low- and high-dose samples. The high-dose sample showed a significant difference between point-by-point and average matrix normalization because the matrix signal decreased in the vicinity of the implant peak, as observed in a previous study. The dose from point-by-point normalization was in close agreement with that determined by INAA. No clear difference in measurement repeatability was seen when comparing Si 2- and Si 3- as matrix references with AsSi -.

The association between vitamin K status and knee osteoarthritis features in older adults: the Health, Aging and Body Composition Study

USDA-ARS?s Scientific Manuscript database

Background: Vitamin K-dependent proteins, including the mineralization inhibitor matrix-gla protein (MGP), are found in joint tissues including cartilage and bone. Previous studies suggest low vitamin K status is associated with higher osteoarthritis (OA) prevalence and incidence. Objective: To cla...

Genetic Response of Rat Supraspinatus Tendon and Muscle to Exercise

PubMed Central

Rooney, Sarah Ilkhanipour; Tobias, John W.; Bhatt, Pankti R.; Kuntz, Andrew F.; Soslowsky, Louis J.

2015-01-01

Inflammation is a complex, biologic event that aims to protect and repair tissue. Previous studies suggest that inflammation is critical to induce a healing response following acute injury; however, whether similar inflammatory responses occur as a result of beneficial, non-injurious loading is unknown. The objective of this study was to screen for alterations in a subset of inflammatory and extracellular matrix genes to identify the responses of rat supraspinatus tendon and muscle to a known, non-injurious loading condition. We sought to define how a subset of genes representative of specific inflammation and matrix turnover pathways is altered in supraspinatus tendon and muscle 1) acutely following a single loading bout and 2) chronically following repeated loading bouts. In this study, Sprague-Dawley rats in the acute group ran a single bout of non-injurious exercise on a flat treadmill (10 m/min, 1 hour) and were sacrificed 12 or 24 hours after. Rats in the chronic group ran 5 days/wk for 1 or 8 weeks. A control group maintained normal cage activity. Supraspinatus muscle and tendon were harvested for RNA extractions, and a custom Panomics QuantiGene 2.0 multiplex assay was used to detect 48 target and 3 housekeeping genes. Muscle/tendon and acute/chronic groups had distinct gene expression. Components of the arachidonic acid cascade and matrix metalloproteinases and their inhibitors were altered with acute and chronic exercise. Collagen expression increased. Using a previously validated model of non-injurious exercise, we have shown that supraspinatus tendon and muscle respond to acute and chronic exercise by regulating inflammatory- and matrix turnover-related genes, suggesting that these pathways are involved in the beneficial adaptations to exercise. PMID:26447778

Headspace versus direct immersion solid phase microextraction in complex matrixes: investigation of analyte behavior in multicomponent mixtures.

PubMed

Gionfriddo, Emanuela; Souza-Silva, Érica A; Pawliszyn, Janusz

2015-08-18

This work aims to investigate the behavior of analytes in complex mixtures and matrixes with the use of solid-phase microextraction (SPME). Various factors that influence analyte uptake such as coating chemistry, extraction mode, the physicochemical properties of analytes, and matrix complexity were considered. At first, an aqueous system containing analytes bearing different hydrophobicities, molecular weights, and chemical functionalities was investigated by using commercially available liquid and solid porous coatings. The differences in the mass transfer mechanisms resulted in a more pronounced occurrence of coating saturation in headspace mode. Contrariwise, direct immersion extraction minimizes the occurrence of artifacts related to coating saturation and provides enhanced extraction of polar compounds. In addition, matrix-compatible PDMS-modified solid coatings, characterized by a new morphology that avoids coating fouling, were compared to their nonmodified analogues. The obtained results indicate that PDMS-modified coatings reduce artifacts associated with coating saturation, even in headspace mode. This factor, coupled to their matrix compatibility, make the use of direct SPME very practical as a quantification approach and the best choice for metabolomics studies where wide coverage is intended. To further understand the influence on analyte uptake on a system where additional interactions occur due to matrix components, ex vivo and in vivo sampling conditions were simulated using a starch matrix model, with the aim of mimicking plant-derived materials. Our results corroborate the fact that matrix handling can affect analyte/matrix equilibria, with consequent release of high concentrations of previously bound hydrophobic compounds, potentially leading to coating saturation. Direct immersion SPME limited the occurrence of the artifacts, which confirms the suitability of SPME for in vivo applications. These findings shed light into the implementation of in vivo SPME strategies in quantitative metabolomics studies of complex plant-based systems.

Determinants of Microdamage in Elderly Human Vertebral Trabecular Bone

PubMed Central

Follet, Hélène; Farlay, Delphine; Bala, Yohann; Viguet-Carrin, Stéphanie; Gineyts, Evelyne; Burt-Pichat, Brigitte; Wegrzyn, Julien; Delmas, Pierre; Boivin, Georges; Chapurlat, Roland

2013-01-01

Previous studies have shown that microdamage accumulates in bone as a result of physiological loading and occurs naturally in human trabecular bone. The purpose of this study was to determine the factors associated with pre-existing microdamage in human vertebral trabecular bone, namely age, architecture, hardness, mineral and organic matrix. Trabecular bone cores were collected from human L2 vertebrae (n = 53) from donors 54–95 years of age (22 men and 30 women, 1 unknown) and previous cited parameters were evaluated. Collagen cross-link content (PYD, DPD, PEN and % of collagen) was measured on surrounding trabecular bone. We found that determinants of microdamage were mostly the age of donors, architecture, mineral characteristics and mature enzymatic cross-links. Moreover, linear microcracks were mostly associated with the bone matrix characteristics whereas diffuse damage was associated with architecture. We conclude that linear and diffuse types of microdamage seemed to have different determinants, with age being critical for both types. PMID:23457465

Cryogenic regenerator including sarancarbon heat conduction matrix

NASA Technical Reports Server (NTRS)

Jones, Jack A. (Inventor); Petrick, S. Walter (Inventor); Britcliffe, Michael J. (Inventor)

1989-01-01

A saran carbon matrix is employed to conduct heat through the heat storing volume of a cryogenic regenerator. When helium is adsorbed into the saran carbon matrix, the combination exhibits a volumetric specific heat much higher than previously used lead balls. A helium adsorbed saran regenerator should allow much lower refrigerator temperatures than those practically obtainable with lead based regenerators for regenerator type refrigeration systems.

Possible evidence of amide bond formation between sinapinic acid and lysine-containing bacterial proteins by matrix-assisted laser desorption/ionization (MALDI) at 355 nm

USDA-ARS?s Scientific Manuscript database

We previously reported the apparent formation of matrix adducts of 3,5-dimethoxy-4-hydroxy-cinnamic acid (sinapinic acid or SA) via covalent attachment to disulfide bond-containing proteins (HdeA, HdeB and YbgS) from bacterial cell lysates ionized by matrix-assisted laser desorption/ionization (MALD...

Novel entries in a fungal biofilm matrix encyclopedia.

PubMed

Zarnowski, Robert; Westler, William M; Lacmbouh, Ghislain Ade; Marita, Jane M; Bothe, Jameson R; Bernhardt, Jörg; Lounes-Hadj Sahraoui, Anissa; Fontaine, Joël; Sanchez, Hiram; Hatfield, Ronald D; Ntambi, James M; Nett, Jeniel E; Mitchell, Aaron P; Andes, David R

2014-08-05

Virulence of Candida is linked with its ability to form biofilms. Once established, biofilm infections are nearly impossible to eradicate. Biofilm cells live immersed in a self-produced matrix, a blend of extracellular biopolymers, many of which are uncharacterized. In this study, we provide a comprehensive analysis of the matrix manufactured by Candida albicans both in vitro and in a clinical niche animal model. We further explore the function of matrix components, including the impact on drug resistance. We uncovered components from each of the macromolecular classes (55% protein, 25% carbohydrate, 15% lipid, and 5% nucleic acid) in the C. albicans biofilm matrix. Three individual polysaccharides were identified and were suggested to interact physically. Surprisingly, a previously identified polysaccharide of functional importance, β-1,3-glucan, comprised only a small portion of the total matrix carbohydrate. Newly described, more abundant polysaccharides included α-1,2 branched α-1,6-mannans (87%) associated with unbranched β-1,6-glucans (13%) in an apparent mannan-glucan complex (MGCx). Functional matrix proteomic analysis revealed 458 distinct activities. The matrix lipids consisted of neutral glycerolipids (89.1%), polar glycerolipids (10.4%), and sphingolipids (0.5%). Examination of matrix nucleic acid identified DNA, primarily noncoding sequences. Several of the in vitro matrix components, including proteins and each of the polysaccharides, were also present in the matrix of a clinically relevant in vivo biofilm. Nuclear magnetic resonance (NMR) analysis demonstrated interaction of aggregate matrix with the antifungal fluconazole, consistent with a role in drug impedance and contribution of multiple matrix components. Importance: This report is the first to decipher the complex and unique macromolecular composition of the Candida biofilm matrix, demonstrate the clinical relevance of matrix components, and show that multiple matrix components are needed for protection from antifungal drugs. The availability of these biochemical analyses provides a unique resource for further functional investigation of the biofilm matrix, a defining trait of this lifestyle. Copyright © 2014 Zarnowski et al.

Dissecting the Impact of Matrix Anchorage and Elasticity in Cell Adhesion

PubMed Central

Pompe, Tilo; Glorius, Stefan; Bischoff, Thomas; Uhlmann, Ina; Kaufmann, Martin; Brenner, Sebastian; Werner, Carsten

2009-01-01

Abstract Extracellular matrices determine cellular fate decisions through the regulation of intracellular force and stress. Previous studies suggest that matrix stiffness and ligand anchorage cause distinct signaling effects. We show herein how defined noncovalent anchorage of adhesion ligands to elastic substrates allows for dissection of intracellular adhesion signaling pathways related to matrix stiffness and receptor forces. Quantitative analysis of the mechanical balance in cell adhesion using traction force microscopy revealed distinct scalings of the strain energy imparted by the cells on the substrates dependent either on matrix stiffness or on receptor force. Those scalings suggested the applicability of a linear elastic theoretical framework for the description of cell adhesion in a certain parameter range, which is cell-type-dependent. Besides the deconvolution of biophysical adhesion signaling, site-specific phosphorylation of focal adhesion kinase, dependent either on matrix stiffness or on receptor force, also demonstrated the dissection of biochemical signaling events in our approach. Moreover, the net contractile moment of the adherent cells and their strain energy exerted on the elastic substrate was found to be a robust measure of cell adhesion with a unifying power-law scaling exponent of 1.5 independent of matrix stiffness. PMID:19843448

Reducing the orientation influence of Mueller matrix measurements for anisotropic scattering media

NASA Astrophysics Data System (ADS)

Sun, Minghao; He, Honghui; Zeng, Nan; Du, E.; He, Yonghong; Ma, Hui

2014-09-01

Mueller matrix polarimetry techniques contain rich micro-structural information of samples, such as the sizes and refractive indices of scatterers. Recently, Mueller matrix imaging methods have shown great potentials as powerful tools for biomedical diagnosis. However, the orientations of anisotropic fibrous structures in tissues have prominent influence on Mueller matrix measurements, resulting in difficulties for extracting micro-structural information effectively. In this paper, we apply the backscattering Mueller matrix imaging technique to biological samples with different microstructures, such as chicken heart muscle, bovine skeletal muscle, porcine liver and fat tissues. Experimental results show that the directions of the muscle fibers have prominent influence on the Mueller matrix elements. In order to reduce the orientation influence, we adopt the rotation-independent MMT and RLPI parameters, which were proposed in our previous studies, to the tissue samples. Preliminary results in this paper show that the orientation-independent parameters and their statistic features are helpful for analyzing the tissues to obtain their micro-structural properties. Since the micro-structure variations are often related to the pathological changes, the method can be applied to microscope imaging techniques and used to detect abnormal tissues such as cancer and other lesions for diagnosis purposes.

Characterizing microstructural features of biomedical samples by statistical analysis of Mueller matrix images

NASA Astrophysics Data System (ADS)

He, Honghui; Dong, Yang; Zhou, Jialing; Ma, Hui

2017-03-01

As one of the salient features of light, polarization contains abundant structural and optical information of media. Recently, as a comprehensive description of polarization property, the Mueller matrix polarimetry has been applied to various biomedical studies such as cancerous tissues detections. In previous works, it has been found that the structural information encoded in the 2D Mueller matrix images can be presented by other transformed parameters with more explicit relationship to certain microstructural features. In this paper, we present a statistical analyzing method to transform the 2D Mueller matrix images into frequency distribution histograms (FDHs) and their central moments to reveal the dominant structural features of samples quantitatively. The experimental results of porcine heart, intestine, stomach, and liver tissues demonstrate that the transformation parameters and central moments based on the statistical analysis of Mueller matrix elements have simple relationships to the dominant microstructural properties of biomedical samples, including the density and orientation of fibrous structures, the depolarization power, diattenuation and absorption abilities. It is shown in this paper that the statistical analysis of 2D images of Mueller matrix elements may provide quantitative or semi-quantitative criteria for biomedical diagnosis.

Fabrication of metal matrix composites by powder metallurgy: A review

NASA Astrophysics Data System (ADS)

Manohar, Guttikonda; Dey, Abhijit; Pandey, K. M.; Maity, S. R.

2018-04-01

Now a day's metal matrix components are used in may industries and it finds the applications in many fields so, to make it as better performable materials. So, the need to increase the mechanical properties of the composites is there. As seen from previous studies major problem faced by the MMC's are wetting, interface bonding between reinforcement and matrix material while they are prepared by conventional methods like stir casting, squeeze casting and other techniques which uses liquid molten metals. So many researchers adopt PM to eliminate these defects and to increase the mechanical properties of the composites. Powder metallurgy is one of the better ways to prepare composites and Nano composites. And the major problem faced by the conventional methods are uniform distribution of the reinforcement particles in the matrix alloy, many researchers tried to homogeneously dispersion of reinforcements in matrix but they find it difficult through conventional methods, among all they find ultrasonic dispersion is efficient. This review article is mainly concentrated on importance of powder metallurgy in homogeneous distribution of reinforcement in matrix by ball milling or mechanical milling and how powder metallurgy improves the mechanical properties of the composites.

Clonorchis sinensis excretory-secretory products regulate migration and invasion in cholangiocarcinoma cells via extracellular signal-regulated kinase 1/2/nuclear factor-κB-dependent matrix metalloproteinase-9 expression.

PubMed

Pak, Jhang Ho; Shin, Jimin; Song, In-Sung; Shim, Sungbo; Jang, Sung-Wuk

2017-01-01

Matrix metalloproteinase-9 plays an important role in the invasion and metastasis of various types of cancer cells. We have previously reported that excretory-secretory products from Clonorchis sinensis increases matrix metalloproteinase-9 expression. However, the regulatory mechanisms through which matrix metalloproteinase-9 expression affects cholangiocarcinoma development remain unclear. In the current study, we examined the potential role of excretory-secretory products in regulating the migration and invasion of various cholangiocarcinoma cell lines. We demonstrated that excretory-secretory products significantly induced matrix metalloproteinase-9 expression and activity in a concentration-dependent manner. Reporter gene and chromatin immunoprecipitation assays showed that excretory-secretory products induced matrix metalloproteinase-9 expression by enhancing the activity of nuclear factor-kappa B. Moreover, excretory-secretory products induced the degradation and phosphorylation of IκBα and stimulated nuclear factor-kappa B p65 nuclear translocation, which was regulated by extracellular signal-regulated kinase 1/2. Taken together, our findings indicated that the excretory-secretory product-dependent enhancement of matrix metalloproteinase-9 activity and subsequent induction of IκBα and nuclear factor-kappa B activities may contribute to the progression of cholangiocarcinoma. Copyright © 2016 Australian Society for Parasitology. Published by Elsevier Ltd. All rights reserved.

Numerical modelling of transdermal delivery from matrix systems: parametric study and experimental validation with silicone matrices.

PubMed

Snorradóttir, Bergthóra S; Jónsdóttir, Fjóla; Sigurdsson, Sven Th; Másson, Már

2014-08-01

A model is presented for transdermal drug delivery from single-layered silicone matrix systems. The work is based on our previous results that, in particular, extend the well-known Higuchi model. Recently, we have introduced a numerical transient model describing matrix systems where the drug dissolution can be non-instantaneous. Furthermore, our model can describe complex interactions within a multi-layered matrix and the matrix to skin boundary. The power of the modelling approach presented here is further illustrated by allowing the possibility of a donor solution. The model is validated by a comparison with experimental data, as well as validating the parameter values against each other, using various configurations with donor solution, silicone matrix and skin. Our results show that the model is a good approximation to real multi-layered delivery systems. The model offers the ability of comparing drug release for ibuprofen and diclofenac, which cannot be analysed by the Higuchi model because the dissolution in the latter case turns out to be limited. The experiments and numerical model outlined in this study could also be adjusted to more general formulations, which enhances the utility of the numerical model as a design tool for the development of drug-loaded matrices for trans-membrane and transdermal delivery. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

Efficient diagonalization of the sparse matrices produced within the framework of the UK R-matrix molecular codes

NASA Astrophysics Data System (ADS)

Galiatsatos, P. G.; Tennyson, J.

2012-11-01

The most time consuming step within the framework of the UK R-matrix molecular codes is that of the diagonalization of the inner region Hamiltonian matrix (IRHM). Here we present the method that we follow to speed up this step. We use shared memory machines (SMM), distributed memory machines (DMM), the OpenMP directive based parallel language, the MPI function based parallel language, the sparse matrix diagonalizers ARPACK and PARPACK, a variation for real symmetric matrices of the official coordinate sparse matrix format and finally a parallel sparse matrix-vector product (PSMV). The efficient application of the previous techniques rely on two important facts: the sparsity of the matrix is large enough (more than 98%) and in order to get back converged results we need a small only part of the matrix spectrum.

Neutrinoless ββ decay mediated by the exchange of light and heavy neutrinos: the role of nuclear structure correlations

NASA Astrophysics Data System (ADS)

Menéndez, J.

2018-01-01

Neutrinoless β β decay nuclear matrix elements calculated with the shell model and energy-density functional theory typically disagree by more than a factor of two in the standard scenario of light-neutrino exchange. In contrast, for a decay mediated by sterile heavy neutrinos the deviations are reduced to about 50%, an uncertainty similar to the one due to short-range effects. We compare matrix elements in the light- and heavy-neutrino-exchange channels, exploring the radial, momentum transfer and angular momentum-parity matrix element distributions, and considering transitions that involve correlated and uncorrelated nuclear states. We argue that the shorter-range heavy-neutrino exchange is less sensitive to collective nuclear correlations, and that discrepancies in matrix elements are mostly due to the treatment of long-range correlations in many-body calculations. Our analysis supports previous studies suggesting that isoscalar pairing correlations, which affect mostly the longer-range part of the neutrinoless β β decay operator, are partially responsible for the differences between nuclear matrix elements in the standard light-neutrino-exchange mechanism.

Massive quiver matrix models for massive charged particles in AdS

DOE PAGES

Asplund, Curtis T.; Denef, Frederik; Dzienkowski, Eric

2016-01-11

Here, we present a new class of N = 4 supersymmetric quiver matrix models and argue that it describes the stringy low-energy dynamics of internally wrapped D-branes in four-dimensional anti-de Sitter (AdS) flux compactifications. The Lagrangians of these models differ from previously studied quiver matrix models by the presence of mass terms, associated with the AdS gravitational potential, as well as additional terms dictated by supersymmetry. These give rise to dynamical phenomena typically associated with the presence of fluxes, such as fuzzy membranes, internal cyclotron motion and the appearance of confining strings. We also show how these models can bemore » obtained by dimensional reduction of four-dimensional supersymmetric quiver gauge theories on a three-sphere.« less

Photochemistry of cyclopentadiene isolated in low-temperature argon matrices

NASA Astrophysics Data System (ADS)

Miyazaki, Jun; Yamada, Yasuhiro

2004-04-01

The photochemistry of cyclopentadiene isolated in low-temperature argon matrices was studied by means of IR and UV/VIS spectroscopy. Bicyclo[2.1.0]pent-2-ene was formed by the irradiation of matrix-isolated cyclopentadiene using a super-high-pressure mercury lamp. When the matrix-isolated cyclopentadiene was irradiated with shorter wavelength using a low-pressure mercury lamp, further reactions of bicyclo[2.1.0]pent-2-ene were found to produce allylacetylene and vinylallene. While the photochemistry of cyclopentadiene to form bicyclo[2.1.0]pent-2-ene is known in a solution system, the production of allylacetylene and vinylallene in a matrix-isolated system has never been previously reported. The assignments of the species and the determination of the reaction mechanisms were performed using molecular orbital calculations.

A covariance correction that accounts for correlation estimation to improve finite-sample inference with generalized estimating equations: A study on its applicability with structured correlation matrices

PubMed Central

Westgate, Philip M.

2016-01-01

When generalized estimating equations (GEE) incorporate an unstructured working correlation matrix, the variances of regression parameter estimates can inflate due to the estimation of the correlation parameters. In previous work, an approximation for this inflation that results in a corrected version of the sandwich formula for the covariance matrix of regression parameter estimates was derived. Use of this correction for correlation structure selection also reduces the over-selection of the unstructured working correlation matrix. In this manuscript, we conduct a simulation study to demonstrate that an increase in variances of regression parameter estimates can occur when GEE incorporates structured working correlation matrices as well. Correspondingly, we show the ability of the corrected version of the sandwich formula to improve the validity of inference and correlation structure selection. We also study the relative influences of two popular corrections to a different source of bias in the empirical sandwich covariance estimator. PMID:27818539

A covariance correction that accounts for correlation estimation to improve finite-sample inference with generalized estimating equations: A study on its applicability with structured correlation matrices.

PubMed

Westgate, Philip M

2016-01-01

When generalized estimating equations (GEE) incorporate an unstructured working correlation matrix, the variances of regression parameter estimates can inflate due to the estimation of the correlation parameters. In previous work, an approximation for this inflation that results in a corrected version of the sandwich formula for the covariance matrix of regression parameter estimates was derived. Use of this correction for correlation structure selection also reduces the over-selection of the unstructured working correlation matrix. In this manuscript, we conduct a simulation study to demonstrate that an increase in variances of regression parameter estimates can occur when GEE incorporates structured working correlation matrices as well. Correspondingly, we show the ability of the corrected version of the sandwich formula to improve the validity of inference and correlation structure selection. We also study the relative influences of two popular corrections to a different source of bias in the empirical sandwich covariance estimator.

Sequential two-column electro-Fenton-photolytic reactor for the treatment of winery wastewater.

PubMed

Díez, A M; Sanromán, M A; Pazos, M

2017-01-01

The high amount of winery wastewaters produced each year makes their treatment a priority issue due to their problematic characteristics such as acid pH, high concentration of organic load and colourful compounds. Furthermore, some of these effluents can have dissolved pesticides, due to the previous grape treatments, which are recalcitrant to conventional treatments. Recently, photo-electro-Fenton process has been reported as an effective procedure to mineralize different organic contaminants and a promising technology for the treatment of these complex matrixes. However, the reactors available for applying this process are scarce and they show several limitations. In this study, a sequential two-column reactor for the photo-electro-Fenton treatment was designed and evaluated for the treatment of different pesticides, pirimicarb and pyrimethanil, used in wine production. Both studied pesticides were efficiently removed, and the transformation products were determined. Finally, the treatment of a complex aqueous matrix composed by winery wastewater and the previously studied pesticides was carried out in the designed sequential reactor. The high removals of TOC and COD reached and the low energy consumption demonstrated the efficiency of this new configuration.

Properties of quantum systems via diagonalization of transition amplitudes. II. Systematic improvements of short-time propagation

NASA Astrophysics Data System (ADS)

Vidanović, Ivana; Bogojević, Aleksandar; Balaž, Antun; Belić, Aleksandar

2009-12-01

In this paper, building on a previous analysis [I. Vidanović, A. Bogojević, and A. Belić, preceding paper, Phys. Rev. E 80, 066705 (2009)] of exact diagonalization of the space-discretized evolution operator for the study of properties of nonrelativistic quantum systems, we present a substantial improvement to this method. We apply recently introduced effective action approach for obtaining short-time expansion of the propagator up to very high orders to calculate matrix elements of space-discretized evolution operator. This improves by many orders of magnitude previously used approximations for discretized matrix elements and allows us to numerically obtain large numbers of accurate energy eigenvalues and eigenstates using numerical diagonalization. We illustrate this approach on several one- and two-dimensional models. The quality of numerically calculated higher-order eigenstates is assessed by comparison with semiclassical cumulative density of states.

Convergence in High Probability of the Quantum Diffusion in a Random Band Matrix Model

NASA Astrophysics Data System (ADS)

Margarint, Vlad

2018-06-01

We consider Hermitian random band matrices H in d ≥slant 1 dimensions. The matrix elements H_{xy}, indexed by x, y \\in Λ \\subset Z^d, are independent, uniformly distributed random variable if |x-y| is less than the band width W, and zero otherwise. We update the previous results of the converge of quantum diffusion in a random band matrix model from convergence of the expectation to convergence in high probability. The result is uniformly in the size |Λ| of the matrix.

Study of the Spectral Properties of Nanocomposites with CdSe Quantum Dots in a Wide Range of Low Temperatures

NASA Astrophysics Data System (ADS)

Magaryan, K. A.; Eremchev, I. Y.; Karimullin, K. R.; Knyazev, M. V.; Mikhailov, M. A.; Vasilieva, I. A.; Klimusheva, G. V.

2015-09-01

Luminescence spectra of the colloidal solution of CdSe quantum dots (in toluene) were studied in a wide range of low temperatures. Samples were synthesized in the liquid crystal matrix of cadmium octanoate (CdC8). A comparative analysis of the obtained data with previous results was performed.

Vectors, Change of Basis and Matrix Representation: Onto-Semiotic Approach in the Analysis of Creating Meaning

ERIC Educational Resources Information Center

Montiel, Mariana; Wilhelmi, Miguel R.; Vidakovic, Draga; Elstak, Iwan

2012-01-01

In a previous study, the onto-semiotic approach was employed to analyse the mathematical notion of different coordinate systems, as well as some situations and university students' actions related to these coordinate systems in the context of multivariate calculus. This study approaches different coordinate systems through the process of change of…

Tests of conformal field theory at the Yang-Lee singularity

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

Wydro, Tomasz; McCabe, John F.

2009-12-14

This paper studies the Yang-Lee edge singularity of 2-dimensional (2D) Ising model based on a quantum spin chain and transfer matrix measurements on the cylinder. Based on finite-size scaling, the low-lying excitation spectrum is found at the Yang-Lee edge singularity. Based on transfer matrix techniques, the single structure constant is evaluated at the Yang-Lee edge singularity. The results of both types of measurements are found to be fully consistent with the predictions for the (A{sub 4}, A{sub 1}) minimal conformal field theory, which was previously identified with this critical point.

Immunomodulatory effects of amniotic membrane matrix incorporated into collagen scaffolds.

PubMed

Hortensius, Rebecca A; Ebens, Jill H; Harley, Brendan A C

2016-06-01

Adult tendon wound repair is characterized by the formation of disorganized collagen matrix which leads to decreases in mechanical properties and scar formation. Studies have linked this scar formation to the inflammatory phase of wound healing. Instructive biomaterials designed for tendon regeneration are often designed to provide both structural and cellular support. In order to facilitate regeneration, success may be found by tempering the body's inflammatory response. This work combines collagen-glycosaminoglycan scaffolds, previously developed for tissue regeneration, with matrix materials (hyaluronic acid and amniotic membrane) that have been shown to promote healing and decreased scar formation in skin studies. The results presented show that scaffolds containing amniotic membrane matrix have significantly increased mechanical properties and that tendon cells within these scaffolds have increased metabolic activity even when the media is supplemented with the pro-inflammatory cytokine interleukin-1 beta. Collagen scaffolds containing hyaluronic acid or amniotic membrane also temper the expression of genes associated with the inflammatory response in normal tendon healing (TNF-α, COLI, MMP-3). These results suggest that alterations to scaffold composition, to include matrix known to decrease scar formation in vivo, can modify the inflammatory response in tenocytes. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1332-1342, 2016. © 2016 Wiley Periodicals, Inc.

Anti-proteolytic capacity and bonding durability of proanthocyanidin-biomodified demineralized dentin matrix

PubMed Central

Liu, Rui-Rui; Fang, Ming; Zhang, Ling; Tang, Cheng-Fang; Dou, Qi; Chen, Ji-Hua

2014-01-01

Our previous studies showed that biomodification of demineralized dentin collagen with proanthocyanidin (PA) for a clinically practical duration improves the mechanical properties of the dentin matrix and the immediate resin–dentin bond strength. The present study sought to evaluate the ability of PA biomodification to reduce collagenase-induced biodegradation of demineralized dentin matrix and dentin/adhesive interfaces in a clinically relevant manner. The effects of collagenolytic and gelatinolytic activity on PA-biomodified demineralized dentin matrix were analysed by hydroxyproline assay and gelatin zymography. Then, resin-/dentin-bonded specimens were prepared and challenged with bacterial collagenases. Dentin treated with 2% chlorhexidine and untreated dentin were used as a positive and negative control, respectively. Collagen biodegradation, the microtensile bond strengths of bonded specimens and the micromorphologies of the fractured interfaces were assessed. The results revealed that both collagenolytic and gelatinolytic activity on demineralized dentin were notably inhibited in the PA-biomodified groups, irrespective of PA concentration and biomodification duration. When challenged with exogenous collagenases, PA-biomodified bonded specimens exhibited significantly less biodegradation and maintained higher bond strengths than the untreated control. These results suggest that PA biomodification was effective at inhibiting proteolytic activity on demineralized dentin matrix and at stabilizing the adhesive/dentin interface against enzymatic degradation, is a new concept that has the potential to improve bonding durability. PMID:24810807

Proteomic analysis of the organic matrix of the abalone Haliotis asinina calcified shell

PubMed Central

2010-01-01

Background The formation of the molluscan shell is regulated to a large extent by a matrix of extracellular macromolecules that are secreted by the shell forming tissue, the mantle. This so called "calcifying matrix" is a complex mixture of proteins and glycoproteins that is assembled and occluded within the mineral phase during the calcification process. While the importance of the calcifying matrix to shell formation has long been appreciated, most of its protein components remain uncharacterised. Results Recent expressed sequence tag (EST) investigations of the mantle tissue from the tropical abalone (Haliotis asinina) provide an opportunity to further characterise the proteins in the shell by a proteomic approach. In this study, we have identified a total of 14 proteins from distinct calcified layers of the shell. Only two of these proteins have been previously characterised from abalone shells. Among the novel proteins are several glutamine- and methionine-rich motifs and hydrophobic glycine-, alanine- and acidic aspartate-rich domains. In addition, two of the new proteins contained Kunitz-like and WAP (whey acidic protein) protease inhibitor domains. Conclusion This is one of the first comprehensive proteomic study of a molluscan shell, and should provide a platform for further characterization of matrix protein functions and interactions. PMID:21050442

HBM Mice Have Altered Bone Matrix Composition And Improved Material Toughness

DOE PAGES

Ross, Ryan D.; Mashiatulla, Maleeha; Acerbo, Alvin S.; ...

2016-05-26

Here, the G171V mutation in the low density lipoprotein receptor-related protein 5 (LRP5) leads to a high bone mass (HBM) phenotype. Studies using an HBM transgenic mouse model have consistently found increased bone mass and whole-bone strength, but little attention has been paid to bone matrix quality. The current study sought to determine if the cortical bone matrix composition differs in HBM and wild-type mice and to determine how much of the variance in bone material properties is explained by variance in matrix composition. Consistent with previous studies, HBM mice had greater cortical area, moment of inertia, ultimate force, bendingmore » stiffness, and energy to failure than wild-type animals. Interestingly, the increased energy to failure was primarily caused by a large increase in post-yield behavior, with no difference in pre-yield behavior. The HBM mice had increased mineral-to-matrix and collagen cross-link ratios, and decreased crystallinity and carbonate substitution, but no differences in crystal length, intra-fibular strains, and mineral spacing compared to wild-type controls. The largest difference in material properties was a 2-fold increase in the modulus of toughness in HBM mice. Step-wise regression analyses found weak correlations between matrix composition and material properties, and interestingly, the matrix compositional parameters associated with the material properties varied between the wild-type and HBM genotypes. Although the mechanisms controlling the paradoxical combination of more mineralized yet tougher bone in HBM mice remain to be fully explained, the findings suggest that LRP5 represents a target to not only build greater bone quantity, but also to improve bone quality.« less

HBM Mice Have Altered Bone Matrix Composition And Improved Material Toughness

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

Ross, Ryan D.; Mashiatulla, Maleeha; Acerbo, Alvin S.

Here, the G171V mutation in the low density lipoprotein receptor-related protein 5 (LRP5) leads to a high bone mass (HBM) phenotype. Studies using an HBM transgenic mouse model have consistently found increased bone mass and whole-bone strength, but little attention has been paid to bone matrix quality. The current study sought to determine if the cortical bone matrix composition differs in HBM and wild-type mice and to determine how much of the variance in bone material properties is explained by variance in matrix composition. Consistent with previous studies, HBM mice had greater cortical area, moment of inertia, ultimate force, bendingmore » stiffness, and energy to failure than wild-type animals. Interestingly, the increased energy to failure was primarily caused by a large increase in post-yield behavior, with no difference in pre-yield behavior. The HBM mice had increased mineral-to-matrix and collagen cross-link ratios, and decreased crystallinity and carbonate substitution, but no differences in crystal length, intra-fibular strains, and mineral spacing compared to wild-type controls. The largest difference in material properties was a 2-fold increase in the modulus of toughness in HBM mice. Step-wise regression analyses found weak correlations between matrix composition and material properties, and interestingly, the matrix compositional parameters associated with the material properties varied between the wild-type and HBM genotypes. Although the mechanisms controlling the paradoxical combination of more mineralized yet tougher bone in HBM mice remain to be fully explained, the findings suggest that LRP5 represents a target to not only build greater bone quantity, but also to improve bone quality.« less

Comparison of two matrix data structures for advanced CSM testbed applications

NASA Technical Reports Server (NTRS)

Regelbrugge, M. E.; Brogan, F. A.; Nour-Omid, B.; Rankin, C. C.; Wright, M. A.

1989-01-01

The first section describes data storage schemes presently used by the Computational Structural Mechanics (CSM) testbed sparse matrix facilities and similar skyline (profile) matrix facilities. The second section contains a discussion of certain features required for the implementation of particular advanced CSM algorithms, and how these features might be incorporated into the data storage schemes described previously. The third section presents recommendations, based on the discussions of the prior sections, for directing future CSM testbed development to provide necessary matrix facilities for advanced algorithm implementation and use. The objective is to lend insight into the matrix structures discussed and to help explain the process of evaluating alternative matrix data structures and utilities for subsequent use in the CSM testbed.

Structure and assembly of a paramyxovirus matrix protein

PubMed Central

Battisti, Anthony J.; Meng, Geng; Winkler, Dennis C.; McGinnes, Lori W.; Plevka, Pavel; Steven, Alasdair C.; Morrison, Trudy G.; Rossmann, Michael G.

2012-01-01

Many pleomorphic, lipid-enveloped viruses encode matrix proteins that direct their assembly and budding, but the mechanism of this process is unclear. We have combined X-ray crystallography and cryoelectron tomography to show that the matrix protein of Newcastle disease virus, a paramyxovirus and relative of measles virus, forms dimers that assemble into pseudotetrameric arrays that generate the membrane curvature necessary for virus budding. We show that the glycoproteins are anchored in the gaps between the matrix proteins and that the helical nucleocapsids are associated in register with the matrix arrays. About 90% of virions lack matrix arrays, suggesting that, in agreement with previous biological observations, the matrix protein needs to dissociate from the viral membrane during maturation, as is required for fusion and release of the nucleocapsid into the host’s cytoplasm. Structure and sequence conservation imply that other paramyxovirus matrix proteins function similarly. PMID:22891297

Structure and assembly of a paramyxovirus matrix protein.

PubMed

Battisti, Anthony J; Meng, Geng; Winkler, Dennis C; McGinnes, Lori W; Plevka, Pavel; Steven, Alasdair C; Morrison, Trudy G; Rossmann, Michael G

2012-08-28

Many pleomorphic, lipid-enveloped viruses encode matrix proteins that direct their assembly and budding, but the mechanism of this process is unclear. We have combined X-ray crystallography and cryoelectron tomography to show that the matrix protein of Newcastle disease virus, a paramyxovirus and relative of measles virus, forms dimers that assemble into pseudotetrameric arrays that generate the membrane curvature necessary for virus budding. We show that the glycoproteins are anchored in the gaps between the matrix proteins and that the helical nucleocapsids are associated in register with the matrix arrays. About 90% of virions lack matrix arrays, suggesting that, in agreement with previous biological observations, the matrix protein needs to dissociate from the viral membrane during maturation, as is required for fusion and release of the nucleocapsid into the host's cytoplasm. Structure and sequence conservation imply that other paramyxovirus matrix proteins function similarly.

Optoelectronic switch matrix as a look-up table for residue arithmetic.

PubMed

Macdonald, R I

1987-10-01

The use of optoelectronic matrix switches to perform look-up table functions in residue arithmetic processors is proposed. In this application, switchable detector arrays give the advantage of a greatly reduced requirement for optical sources by comparison with previous optoelectronic residue processors.

Fracture mechanics of matrix cracking and delamination in glass/epoxy laminates

NASA Technical Reports Server (NTRS)

Caslini, M.; Zanotti, C.; Obrien, T. K.

1986-01-01

This study focused on characterizing matrix cracking and delamination behavior in multidirectional laminates. Static tension and tension-tension fatigue tests were conducted on two different layups. Damage onset, accumulation, and residual properties were measured. Matrix cracking was shown to have a considerable influence on residual stiffness of glass epoxy laminates, and could be predicted reasonably well for cracks in 90 deg piles using a simple shear lag analysis. A fracture mechanics analysis for the strain energy release rate associated with 90 deg ply-matrix crack formation was developed and was shown to correlate the onset of 90 deg ply cracks in different laminates. The linear degradation of laminate modulus with delamination area, previously observed for graphite epoxy laminates, was predicted for glass epoxy laminates using a simple rule of mixtures analysis. The strain energy release rate associated with edge delamination formation under static and cyclic loading was difficult to analyze because of the presence of several contemporary damage phenomena.

Extracellular DNA facilitates the formation of functional amyloids in Staphylococcus aureus biofilms.

PubMed

Schwartz, Kelly; Ganesan, Mahesh; Payne, David E; Solomon, Michael J; Boles, Blaise R

2016-01-01

Persistent staphylococcal infections often involve surface-associated communities called biofilms. Staphylococcus aureus biofilm development is mediated by the co-ordinated production of the biofilm matrix, which can be composed of polysaccharides, extracellular DNA (eDNA) and proteins including amyloid fibers. The nature of the interactions between matrix components, and how these interactions contribute to the formation of matrix, remain unclear. Here we show that the presence of eDNA in S. aureus biofilms promotes the formation of amyloid fibers. Conditions or mutants that do not generate eDNA result in lack of amyloids during biofilm growth despite the amyloidogeneic subunits, phenol soluble modulin peptides, being produced. In vitro studies revealed that the presence of DNA promotes amyloid formation by PSM peptides. Thus, this work exposes a previously unacknowledged interaction between biofilm matrix components that furthers our understanding of functional amyloid formation and S. aureus biofilm biology. © 2015 The Authors. Molecular Microbiology published by John Wiley & Sons Ltd.

Bone Formation is Affected by Matrix Advanced Glycation End Products (AGEs) In Vivo.

PubMed

Yang, Xiao; Mostafa, Ahmed Jenan; Appleford, Mark; Sun, Lian-Wen; Wang, Xiaodu

2016-10-01

Advanced glycation end products (AGEs) accumulate in bone extracellular matrix as people age. Although previous evidence shows that the accumulation of AGEs in bone matrix may impose significant effects on bone cells, the effect of matrix AGEs on bone formation in vivo is still poorly understood. To address this issue, this study used a unique rat model with autograft implant to investigate the in vivo response of bone formation to matrix AGEs. Fluorochrome biomarkers were sequentially injected into rats to label the dynamic bone formation in the presence of elevated levels of matrix AGEs. After sacrificing animals, dynamic histomorphometry was performed to determine mineral apposition rate (MAR), mineralized surface per bone surface (MS/BS), and bone formation rate (BFR). Finally, nanoindentation tests were performed to assess mechanical properties of newly formed bone tissues. The results showed that MAR, MS/BS, and BFR were significantly reduced in the vicinity of implant cores with high concentration of matrix AGEs, suggesting that bone formation activities by osteoblasts were suppressed in the presence of elevated matrix AGEs. In addition, MAR and BFR were found to be dependent on the surrounding environment of implant cores (i.e., cortical or trabecular tissues). Moreover, MS/BS and BFR were also dependent on how far the implant cores were away from the growth plate. These observations suggest that the effect of matrix AGEs on bone formation is dependent on the biological milieu around the implants. Finally, nanoindentation test results indicated that the indentation modulus and hardness of newly formed bone tissues were not affected by the presence of elevated matrix AGEs. In summary, high concentration of matrix AGEs may slow down the bone formation process in vivo, while imposing little effects on bone mineralization.

Solute atmospheres at dislocations

DOE PAGES

Hirth, John P.; Barnett, David M.; Hoagland, Richard G.

2017-06-01

In this study, a two-dimensional plane strain elastic solution is determined for the Cottrell solute atmosphere around an edge dislocation in an infinitely long cylinder of finite radius (the matrix), in which rows of solutes are represented by cylindrical rods with in-plane hydrostatic misfit (axial misfit is also considered). The periphery of the matrix is traction-free, thus introducing an image solute field which generates a solute-solute interaction energy that has not been considered previously. The relevant energy for the field of any distribution of solutes coexistent with a single edge dislocation along the (matrix) cylinder axis is determined, and coherencymore » effects are discussed and studied. Monte Carlo simulations accounting for all pertinent interactions over a range of temperatures are found to yield solute distributions different from classical results, namely, (1) Fermi-Dirac condensations at low temperatures at the free surface, (2) the majority of the atmosphere lying within an unexpectedly large non-linear interaction region near the dislocation core, and (3) temperature-dependent asymmetrical solute arrangements that promote bending. The solute distributions at intermediate temperatures show a 1/r dependence in agreement with previous linearized approximations. With a standard state of solute corresponding to a mean concentration, c 0, the relevant interaction energy expression presented in this work is valid when extended to large concentrations for which Henry's Law and Vegard's Law do not apply.« less

Solute atmospheres at dislocations

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

Hirth, John P.; Barnett, David M.; Hoagland, Richard G.

In this study, a two-dimensional plane strain elastic solution is determined for the Cottrell solute atmosphere around an edge dislocation in an infinitely long cylinder of finite radius (the matrix), in which rows of solutes are represented by cylindrical rods with in-plane hydrostatic misfit (axial misfit is also considered). The periphery of the matrix is traction-free, thus introducing an image solute field which generates a solute-solute interaction energy that has not been considered previously. The relevant energy for the field of any distribution of solutes coexistent with a single edge dislocation along the (matrix) cylinder axis is determined, and coherencymore » effects are discussed and studied. Monte Carlo simulations accounting for all pertinent interactions over a range of temperatures are found to yield solute distributions different from classical results, namely, (1) Fermi-Dirac condensations at low temperatures at the free surface, (2) the majority of the atmosphere lying within an unexpectedly large non-linear interaction region near the dislocation core, and (3) temperature-dependent asymmetrical solute arrangements that promote bending. The solute distributions at intermediate temperatures show a 1/r dependence in agreement with previous linearized approximations. With a standard state of solute corresponding to a mean concentration, c 0, the relevant interaction energy expression presented in this work is valid when extended to large concentrations for which Henry's Law and Vegard's Law do not apply.« less

An Electrostatic Net Model for the Role of Extracellular DNA in Biofilm Formation by Staphylococcus aureus.

PubMed

Dengler, Vanina; Foulston, Lucy; DeFrancesco, Alicia S; Losick, Richard

2015-12-01

Staphylococcus aureus is an important human pathogen that can form biofilms on various surfaces. These cell communities are protected from the environment by a self-produced extracellular matrix composed of proteins, DNA, and polysaccharide. The exact compositions and roles of the different components are not fully understood. In this study, we investigated the role of extracellular DNA (eDNA) and its interaction with the recently identified cytoplasmic proteins that have a moonlighting role in the biofilm matrix. These matrix proteins associate with the cell surface upon the drop in pH that naturally occurs during biofilm formation, and we found here that this association is independent of eDNA. Conversely, the association of eDNA with the matrix was dependent on matrix proteins. Both proteinase and DNase treatments severely reduced clumping of resuspended biofilms; highlighting the importance of both proteins and eDNA in connecting cells together. By adding an excess of exogenous DNA to DNase-treated biofilm, clumping was partially restored, confirming the crucial role of eDNA in the interconnection of cells. On the basis of our results, we propose that eDNA acts as an electrostatic net, interconnecting cells surrounded by positively charged matrix proteins at a low pH. Extracellular DNA (eDNA) is an important component of the biofilm matrix of diverse bacteria, but its role in biofilm formation is not well understood. Here we report that in Staphylococcus aureus, eDNA associates with cells in a manner that depends on matrix proteins and that eDNA is required to link cells together in the biofilm. These results confirm previous studies that showed that eDNA is an important component of the S. aureus biofilm matrix and also suggest that eDNA acts as an electrostatic net that tethers cells together via the proteinaceous layer of the biofilm matrix. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Field-scale effective matrix diffusion coefficient for fractured rock: results from literature survey.

PubMed

Zhou, Quanlin; Liu, Hui-Hai; Molz, Fred J; Zhang, Yingqi; Bodvarsson, Gudmundur S

2007-08-15

Matrix diffusion is an important mechanism for solute transport in fractured rock. We recently conducted a literature survey on the effective matrix diffusion coefficient, D(m)(e), a key parameter for describing matrix diffusion processes at the field scale. Forty field tracer tests at 15 fractured geologic sites were surveyed and selected for the study, based on data availability and quality. Field-scale D(m)(e) values were calculated, either directly using data reported in the literature, or by reanalyzing the corresponding field tracer tests. The reanalysis was conducted for the selected tracer tests using analytic or semi-analytic solutions for tracer transport in linear, radial, or interwell flow fields. Surveyed data show that the scale factor of the effective matrix diffusion coefficient (defined as the ratio of D(m)(e) to the lab-scale matrix diffusion coefficient, D(m), of the same tracer) is generally larger than one, indicating that the effective matrix diffusion coefficient in the field is comparatively larger than the matrix diffusion coefficient at the rock-core scale. This larger value can be attributed to the many mass-transfer processes at different scales in naturally heterogeneous, fractured rock systems. Furthermore, we observed a moderate, on average trend toward systematic increase in the scale factor with observation scale. This trend suggests that the effective matrix diffusion coefficient is likely to be statistically scale-dependent. The scale-factor value ranges from 0.5 to 884 for observation scales from 5 to 2000 m. At a given scale, the scale factor varies by two orders of magnitude, reflecting the influence of differing degrees of fractured rock heterogeneity at different geologic sites. In addition, the surveyed data indicate that field-scale longitudinal dispersivity generally increases with observation scale, which is consistent with previous studies. The scale-dependent field-scale matrix diffusion coefficient (and dispersivity) may have significant implications for assessing long-term, large-scale radionuclide and contaminant transport events in fractured rock, both for nuclear waste disposal and contaminant remediation.

PKA-induced receptor activator of NF-kappaB ligand (RANKL) expression in vascular cells mediates osteoclastogenesis but not matrix calcification.

PubMed

Tseng, Wendy; Graham, Lucia S; Geng, Yifan; Reddy, Aneela; Lu, Jinxiu; Effros, Rita B; Demer, Linda; Tintut, Yin

2010-09-24

Vascular calcification is a predictor of cardiovascular mortality and is prevalent in patients with atherosclerosis and chronic renal disease. It resembles skeletal osteogenesis, and many bone cells as well as bone-related factors involved in both formation and resorption have been localized in calcified arteries. Previously, we showed that aortic medial cells undergo osteoblastic differentiation and matrix calcification both spontaneously and in response to PKA agonists. The PKA signaling pathway is also involved in regulating bone resorption in skeletal tissue by stimulating osteoblast-production of osteoclast regulating cytokines, including receptor-activator of nuclear κB ligand (RANKL) and interleukins. Therefore, we investigated whether PKA activators regulate osteoclastogenesis in aortic smooth muscle cells (SMC). Treatment of murine SMC with the PKA agonist forskolin stimulated RANKL expression at both mRNA and protein levels. Forskolin also stimulated expression of interleukin-6 but not osteoprotegerin (OPG), an inhibitor of RANKL. Consistent with these results, osteoclastic differentiation was induced when monocytic preosteoclasts (RAW264.7) were cocultured with forskolin-treated aortic SMC. Oxidized phospholipids also slightly induced RANKL expression in T lymphocytes, another potential source of RANKL in the vasculature. Because previous studies have shown that RANKL treatment alone induces matrix calcification of valvular and vascular cells, we next examined whether RANKL mediates forskolin-induced matrix calcification by aortic SMC. RANKL inhibition with OPG had little or no effect on osteoblastic differentiation and matrix calcification of aortic SMC. These findings suggest that, as in skeletal tissues, PKA activation induces bone resorptive factors in the vasculature and that aortic SMC calcification specifically induced by PKA, is not mediated by RANKL.

Flexible matrix composite laminated disk/ring flywheel

NASA Technical Reports Server (NTRS)

Gupta, B. P.; Hannibal, A. J.

1984-01-01

An energy storage flywheel consisting of a quasi-isotropic composite disk overwrapped by a circumferentially wound ring made of carbon fiber and a elastometric matrix is proposed. Through analysis it was demonstrated that with an elastomeric matrix to relieve the radial stresses, a laminated disk/ring flywheel can be designed to store a least 80.3 Wh/kg or about 68% more than previous disk/ring designs. at the same time the simple construction is preserved.

Staggered chiral random matrix theory

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

Osborn, James C.

2011-02-01

We present a random matrix theory for the staggered lattice QCD Dirac operator. The staggered random matrix theory is equivalent to the zero-momentum limit of the staggered chiral Lagrangian and includes all taste breaking terms at their leading order. This is an extension of previous work which only included some of the taste breaking terms. We will also present some results for the taste breaking contributions to the partition function and the Dirac eigenvalues.

Degree of coherence for vectorial electromagnetic fields as the distance between correlation matrices.

PubMed

Luis, Alfredo

2007-04-01

We assess the degree of coherence of vectorial electromagnetic fields in the space-frequency domain as the distance between the cross-spectral density matrix and the identity matrix representing completely incoherent light. This definition is compared with previous approaches. It is shown that this distance provides an upper bound for the degree of coherence and visibility for any pair of scalar waves obtained by linear combinations of the original fields. This same approach emerges when applying a previous definition of global coherence to a Young interferometer.

Method and apparatus for optimized processing of sparse matrices

DOEpatents

Taylor, Valerie E.

1993-01-01

A computer architecture for processing a sparse matrix is disclosed. The apparatus stores a value-row vector corresponding to nonzero values of a sparse matrix. Each of the nonzero values is located at a defined row and column position in the matrix. The value-row vector includes a first vector including nonzero values and delimiting characters indicating a transition from one column to another. The value-row vector also includes a second vector which defines row position values in the matrix corresponding to the nonzero values in the first vector and column position values in the matrix corresponding to the column position of the nonzero values in the first vector. The architecture also includes a circuit for detecting a special character within the value-row vector. Matrix-vector multiplication is executed on the value-row vector. This multiplication is performed by multiplying an index value of the first vector value by a column value from a second matrix to form a matrix-vector product which is added to a previous matrix-vector product.

Thermal form-factor approach to dynamical correlation functions of integrable lattice models

NASA Astrophysics Data System (ADS)

Göhmann, Frank; Karbach, Michael; Klümper, Andreas; Kozlowski, Karol K.; Suzuki, Junji

2017-11-01

We propose a method for calculating dynamical correlation functions at finite temperature in integrable lattice models of Yang-Baxter type. The method is based on an expansion of the correlation functions as a series over matrix elements of a time-dependent quantum transfer matrix rather than the Hamiltonian. In the infinite Trotter-number limit the matrix elements become time independent and turn into the thermal form factors studied previously in the context of static correlation functions. We make this explicit with the example of the XXZ model. We show how the form factors can be summed utilizing certain auxiliary functions solving finite sets of nonlinear integral equations. The case of the XX model is worked out in more detail leading to a novel form-factor series representation of the dynamical transverse two-point function.

Age-Related Effects of Advanced Glycation End Products (Ages) in Bone Matrix on Osteoclastic Resorption.

PubMed

Yang, Xiao; Gandhi, Chintan; Rahman, Md Mizanur; Appleford, Mark; Sun, Lian-Wen; Wang, Xiaodu

2015-12-01

Advanced glycation end products (AGEs) accumulate in bone extracellular matrix as people age. Previous studies have shown controversial results regarding the role of in situ AGEs accumulation in osteoclastic resorption. To address this issue, this study cultured human osteoclast cells directly on human cadaveric bone slices from different age groups (young and elderly) to warrant its relevance to in vivo conditions. The cell culture was terminated on the 3rd, 7th, and 10th day, respectively, to assess temporal changes in the number of differentiated osteoclasts, the number and size of osteoclastic resorption pits, the amount of bone resorbed, as well as the amount of matrix AGEs released in the medium by resorption. In addition, the in situ concentration of matrix AGEs at each resorption pit was also estimated based on its AGEs autofluorescent intensity. The results indicated that (1) osteoclastic resorption activities were significantly correlated with the donor age, showing larger but shallower resorption pits on the elderly bone substrates than on the younger ones; (2) osteoclast resorption activities were not significantly dependent on the in situ AGEs concentration in bone matrix, and (3) a correlation was observed between osteoclast activities and the concentration of AGEs released by the resorption. These results suggest that osteoclasts tend to migrate away from initial anchoring sites on elderly bone substrate during resorption compared to younger bone substrates. However, such behavior is not directly related to the in situ concentration of AGEs in bone matrix at the resorption sites.

Acellular Mouse Kidney ECM can be Used as a Three-Dimensional Substrate to Test the Differentiation Potential of Embryonic Stem Cell Derived Renal Progenitors.

PubMed

Sambi, Manpreet; Chow, Theresa; Whiteley, Jennifer; Li, Mira; Chua, Shawn; Raileanu, Vanessa; Rogers, Ian M

2017-08-01

The development of strategies for tissue regeneration and bio-artificial organ development is based on our understanding of embryogenesis. Differentiation protocols attempt to recapitulate the signaling modalities of gastrulation and organogenesis, coupled with cell selection regimens to isolate the cells of choice. This strategy is impeded by the lack of optimal in vitro culture systems since traditional culture systems do not allow for the three-dimensional interaction between cells and the extracellular matrix. While artificial three-dimensional scaffolds are available, using the natural extracellular matrix scaffold is advantageous because it has a distinct architecture that is difficult to replicate. The adult extracellular matrix is predicted to mediate signaling related to tissue repair not embryogenesis but existing similarities between the two argues that the extracellular matrix will influence the differentiation of stem and progenitor cells. Previous studies using undifferentiated embryonic stem cells grown directly on acellular kidney ECM demonstrated that the acellular kidney supported cell growth but limited differentiation occurred. Using mouse kidney extracellular matrix and mouse embryonic stem cells we report that the extracellular matrix can support the development of kidney structures if the stem cells are first differentiated to kidney progenitor cells before being applied to the acellular organ.

Energy and energy gradient matrix elements with N-particle explicitly correlated complex Gaussian basis functions with L =1

NASA Astrophysics Data System (ADS)

Bubin, Sergiy; Adamowicz, Ludwik

2008-03-01

In this work we consider explicitly correlated complex Gaussian basis functions for expanding the wave function of an N-particle system with the L =1 total orbital angular momentum. We derive analytical expressions for various matrix elements with these basis functions including the overlap, kinetic energy, and potential energy (Coulomb interaction) matrix elements, as well as matrix elements of other quantities. The derivatives of the overlap, kinetic, and potential energy integrals with respect to the Gaussian exponential parameters are also derived and used to calculate the energy gradient. All the derivations are performed using the formalism of the matrix differential calculus that facilitates a way of expressing the integrals in an elegant matrix form, which is convenient for the theoretical analysis and the computer implementation. The new method is tested in calculations of two systems: the lowest P state of the beryllium atom and the bound P state of the positronium molecule (with the negative parity). Both calculations yielded new, lowest-to-date, variational upper bounds, while the number of basis functions used was significantly smaller than in previous studies. It was possible to accomplish this due to the use of the analytic energy gradient in the minimization of the variational energy.

Energy and energy gradient matrix elements with N-particle explicitly correlated complex Gaussian basis functions with L=1.

PubMed

Bubin, Sergiy; Adamowicz, Ludwik

2008-03-21

In this work we consider explicitly correlated complex Gaussian basis functions for expanding the wave function of an N-particle system with the L=1 total orbital angular momentum. We derive analytical expressions for various matrix elements with these basis functions including the overlap, kinetic energy, and potential energy (Coulomb interaction) matrix elements, as well as matrix elements of other quantities. The derivatives of the overlap, kinetic, and potential energy integrals with respect to the Gaussian exponential parameters are also derived and used to calculate the energy gradient. All the derivations are performed using the formalism of the matrix differential calculus that facilitates a way of expressing the integrals in an elegant matrix form, which is convenient for the theoretical analysis and the computer implementation. The new method is tested in calculations of two systems: the lowest P state of the beryllium atom and the bound P state of the positronium molecule (with the negative parity). Both calculations yielded new, lowest-to-date, variational upper bounds, while the number of basis functions used was significantly smaller than in previous studies. It was possible to accomplish this due to the use of the analytic energy gradient in the minimization of the variational energy.

Simple expression for the quantum Fisher information matrix

NASA Astrophysics Data System (ADS)

Šafránek, Dominik

2018-04-01

Quantum Fisher information matrix (QFIM) is a cornerstone of modern quantum metrology and quantum information geometry. Apart from optimal estimation, it finds applications in description of quantum speed limits, quantum criticality, quantum phase transitions, coherence, entanglement, and irreversibility. We derive a surprisingly simple formula for this quantity, which, unlike previously known general expression, does not require diagonalization of the density matrix, and is provably at least as efficient. With a minor modification, this formula can be used to compute QFIM for any finite-dimensional density matrix. Because of its simplicity, it could also shed more light on the quantum information geometry in general.

Comprehensive Thematic T-matrix Reference Database: a 2013-2014 Update

NASA Technical Reports Server (NTRS)

Mishchenko, Michael I.; Zakharova, Nadezhda T.; Khlebtsov, Nikolai G.; Wriedt, Thomas; Videen, Gorden

2014-01-01

This paper is the sixth update to the comprehensive thematic database of peer-reviewedT-matrix publications initiated by us in 2004 and includes relevant publications that have appeared since 2013. It also lists several earlier publications not incorporated in the original database and previous updates.

Evaluation of Subsurface Engineered Barriers at Waste Sites

DTIC Science & Technology

1998-08-01

28 3-4 MATRIX FOR EVALUATING BARRIER CQA/CQC AGAINST ACCEPTABLE INDSUTRY PRACTICES...STANDARDS................................................................. 66 4-2 MATRIX FOR EVALUATING CAP AGAINST ACCEPTABLE INDSUTRY PRACTICES...stated previously, the most widely used technique for containment is the soil-bentonite slurry wall. It is typically the most economical , utilizes low

More on Chemical Reaction Balancing.

ERIC Educational Resources Information Center

Swinehart, D. F.

1985-01-01

A previous article stated that only the matrix method was powerful enough to balance a particular chemical equation. Shows how this equation can be balanced without using the matrix method. The approach taken involves writing partial mathematical reactions and redox half-reactions, and combining them to yield the final balanced reaction. (JN)

Global Analysis Reveals the Complexity of the Human Glomerular Extracellular Matrix

PubMed Central

Byron, Adam; Humphries, Jonathan D.; Randles, Michael J.; Carisey, Alex; Murphy, Stephanie; Knight, David; Brenchley, Paul E.; Zent, Roy; Humphries, Martin J.

2014-01-01

The glomerulus contains unique cellular and extracellular matrix (ECM) components, which are required for intact barrier function. Studies of the cellular components have helped to build understanding of glomerular disease; however, the full composition and regulation of glomerular ECM remains poorly understood. We used mass spectrometry-based proteomics of enriched ECM extracts for a global analysis of human glomerular ECM in vivo and identified a tissue-specific proteome of 144 structural and regulatory ECM proteins. This catalog includes all previously identified glomerular components plus many new and abundant components. Relative protein quantification showed a dominance of collagen IV, collagen I, and laminin isoforms in the glomerular ECM together with abundant collagen VI and TINAGL1. Protein network analysis enabled the creation of a glomerular ECM interactome, which revealed a core of highly connected structural components. More than one half of the glomerular ECM proteome was validated using colocalization studies and data from the Human Protein Atlas. This study yields the greatest number of ECM proteins relative to previous investigations of whole glomerular extracts, highlighting the importance of sample enrichment. It also shows that the composition of glomerular ECM is far more complex than previously appreciated and suggests that many more ECM components may contribute to glomerular development and disease processes. The mass spectrometry proteomics data have been deposited to the ProteomeXchange Consortium with the dataset identifier PXD000456. PMID:24436468

Hidden secrets of deformation: Impact-induced compaction within a CV chondrite

NASA Astrophysics Data System (ADS)

Forman, L. V.; Bland, P. A.; Timms, N. E.; Collins, G. S.; Davison, T. M.; Ciesla, F. J.; Benedix, G. K.; Daly, L.; Trimby, P. W.; Yang, L.; Ringer, S. P.

2016-10-01

The CV3 Allende is one of the most extensively studied meteorites in worldwide collections. It is currently classified as S1-essentially unshocked-using the classification scheme of Stöffler et al. (1991), however recent modelling suggests the low porosity observed in Allende indicates the body should have undergone compaction-related deformation. In this study, we detail previously undetected evidence of impact through use of Electron Backscatter Diffraction mapping to identify deformation microstructures in chondrules, AOAs and matrix grains. Our results demonstrate that forsterite-rich chondrules commonly preserve crystal-plastic microstructures (particularly at their margins); that low-angle boundaries in deformed matrix grains of olivine have a preferred orientation; and that disparities in deformation occur between chondrules, surrounding and non-adjacent matrix grains. We find heterogeneous compaction effects present throughout the matrix, consistent with a highly porous initial material. Given the spatial distribution of these crystal-plastic deformation microstructures, we suggest that this is evidence that Allende has undergone impact-induced compaction from an initially heterogeneous and porous parent body. We suggest that current shock classifications (Stöffler et al., 1991) relying upon data from chondrule interiors do not constrain the complete shock history of a sample.

Computation of the soft anomalous dimension matrix in coordinate space

NASA Astrophysics Data System (ADS)

Mitov, Alexander; Sterman, George; Sung, Ilmo

2010-08-01

We complete the coordinate space calculation of the three-parton correlation in the two-loop massive soft anomalous dimension matrix. The full answer agrees with the result found previously by a different approach. The coordinate space treatment of renormalized two-loop gluon exchange diagrams exhibits their color symmetries in a transparent fashion. We compare coordinate space calculations of the soft anomalous dimension matrix with massive and massless eikonal lines and examine its nonuniform limit at absolute threshold.

Key principles of community-based natural resource management: a synthesis and interpretation of identified effective approaches for managing the commons.

PubMed

Gruber, James S

2010-01-01

This article examines recent research on approaches to community-based environmental and natural resource management and reviews the commonalities and differences between these interdisciplinary and multistakeholder initiatives. To identify the most effective characteristics of Community-based natural resource management (CBNRM), I collected a multiplicity of perspectives from research teams and then grouped findings into a matrix of organizational principles and key characteristics. The matrix was initially vetted (or "field tested") by applying numerous case studies that were previously submitted to the World Bank International Workshop on CBNRM. These practitioner case studies were then compared and contrasted with the findings of the research teams. It is hoped that the developed matrix may be useful to researchers in further focusing research, understanding core characteristics of effective and sustainable CBNRM, providing practitioners with a framework for developing new CBNRM initiatives for managing the commons, and providing a potential resource for academic institutions during their evaluation of their practitioner-focused environmental management and leadership curriculum.

General Population Job Exposure Matrix Applied to a Pooled Study of Prevalent Carpal Tunnel Syndrome

PubMed Central

Dale, Ann Marie; Zeringue, Angelique; Harris-Adamson, Carisa; Rempel, David; Bao, Stephen; Thiese, Matthew S.; Merlino, Linda; Burt, Susan; Kapellusch, Jay; Garg, Arun; Gerr, Fred; Hegmann, Kurt T.; Eisen, Ellen A.; Evanoff, Bradley

2015-01-01

A job exposure matrix may be useful for the study of biomechanical workplace risk factors when individual-level exposure data are unavailable. We used job title–based exposure data from a public data source to construct a job exposure matrix and test exposure-response relationships with prevalent carpal tunnel syndrome (CTS). Exposures of repetitive motion and force from the Occupational Information Network were assigned to 3,452 active workers from several industries, enrolled between 2001 and 2008 from 6 studies. Repetitive motion and force exposures were combined into high/high, high/low, and low/low exposure groupings in each of 4 multivariable logistic regression models, adjusted for personal factors. Although force measures alone were not independent predictors of CTS in these data, strong associations between combined physical exposures of force and repetition and CTS were observed in all models. Consistent with previous literature, this report shows that workers with high force/high repetition jobs had the highest prevalence of CTS (odds ratio = 2.14–2.95) followed by intermediate values (odds ratio = 1.09–2.27) in mixed exposed jobs relative to the lowest exposed workers. This study supports the use of a general population job exposure matrix to estimate workplace physical exposures in epidemiologic studies of musculoskeletal disorders when measures of individual exposures are unavailable. PMID:25700886

Analytic tools for investigating the structure of network reliability measures with regard to observation correlations

NASA Astrophysics Data System (ADS)

Prószyński, W.; Kwaśniak, M.

2018-03-01

A global measure of observation correlations in a network is proposed, together with the auxiliary indices related to non-diagonal elements of the correlation matrix. Based on the above global measure, a specific representation of the correlation matrix is presented, being the result of rigorously proven theorem formulated within the present research. According to the theorem, each positive definite correlation matrix can be expressed by a scale factor and a so-called internal weight matrix. Such a representation made it possible to investigate the structure of the basic reliability measures with regard to observation correlations. Numerical examples carried out for two test networks illustrate the structure of those measures that proved to be dependent on global correlation index. Also, the levels of global correlation are proposed. It is shown that one can readily find an approximate value of the global correlation index, and hence the correlation level, for the expected values of auxiliary indices being the only knowledge about a correlation matrix of interest. The paper is an extended continuation of the previous study of authors that was confined to the elementary case termed uniform correlation. The extension covers arbitrary correlation matrices and a structure of correlation effect.

Solidification of Magnesium (AM50A) / vol%. SiCp composite

NASA Astrophysics Data System (ADS)

Zhang, X.; Hu, H.

2012-01-01

Magnesium matrix composite is one of the advanced lightweight materials with high potential to be used in automotive and aircraft industries due to its low density and high specific mechanical properties. The magnesium composites can be fabricated by adding the reinforcements of fibers or/and particles. In the previous literature, extensive studies have been performed on the development of matrix grain structure of aluminum-based metal matrix composites. However, there is limited information available on the development of grain structure during the solidification of particulate-reinforced magnesium. In this work, a 5 vol.% SiCp particulate-reinforced magnesium (AM50A) matrix composite (AM50A/SiCp) was prepared by stir casting. The solidification behavior of the cast AM50A/SiCp composite was investigated by computer-based thermal analysis. Optical and scanning electron microscopies (SEM) were employed to examine the occurrence of nucleation and grain refinement involved. The results indicate that the addition of SiCp particulates leads to a finer grain structure in the composite compared with the matrix alloy. The refinement of grain structure should be attributed to both the heterogeneous nucleation and the restricted primary crystal growth.

Proteomic analysis of knock-down HLA-G in invasion of human trophoblast cell line JEG-3

PubMed Central

Liu, Haiyan; Liu, Xueyuan; Jin, Hong; Yang, Fengying; Gu, Weirong; Li, Xiaotian

2013-01-01

Previous studies showed that aberrant HLA-G expression in trophoblast cells plays important roles in trophoblast invasion; however, the mechanisms remain to be explored. In this study, we found that suppressed HLA-G expression could dramatically decrease the mRNA and protein expression levels of matrix metalloproteinase 2 and matrix metalloproteinase 9, and in the proteome assay, there were 3 identified proteins namely, prefoldin 1, eukaryotic translation elongation factor 2 and malate dehydrogenase 2, which were verified by Western blot and known to be associated with invasion, cell cycle and cell metabolism, respectively. Collectively, our study indicated a potential involvement of HLA-G in autocrine networks that may regulate prefoldin, MMPs and trophoblast invasion at the maternal-fetal interface in human pregnancy. PMID:24228107

Time-dependent variational principle in matrix-product state manifolds: Pitfalls and potential

NASA Astrophysics Data System (ADS)

Kloss, Benedikt; Lev, Yevgeny Bar; Reichman, David

2018-01-01

We study the applicability of the time-dependent variational principle in matrix-product state manifolds for the long time description of quantum interacting systems. By studying integrable and nonintegrable systems for which the long time dynamics are known we demonstrate that convergence of long time observables is subtle and needs to be examined carefully. Remarkably, for the disordered nonintegrable system we consider the long time dynamics are in good agreement with the rigorously obtained short time behavior and with previous obtained numerically exact results, suggesting that at least in this case, the apparent convergence of this approach is reliable. Our study indicates that, while great care must be exercised in establishing the convergence of the method, it may still be asymptotically accurate for a class of disordered nonintegrable quantum systems.

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

Malone, Fionn D., E-mail: f.malone13@imperial.ac.uk; Lee, D. K. K.; Foulkes, W. M. C.

The recently developed density matrix quantum Monte Carlo (DMQMC) algorithm stochastically samples the N-body thermal density matrix and hence provides access to exact properties of many-particle quantum systems at arbitrary temperatures. We demonstrate that moving to the interaction picture provides substantial benefits when applying DMQMC to interacting fermions. In this first study, we focus on a system of much recent interest: the uniform electron gas in the warm dense regime. The basis set incompleteness error at finite temperature is investigated and extrapolated via a simple Monte Carlo sampling procedure. Finally, we provide benchmark calculations for a four-electron system, comparing ourmore » results to previous work where possible.« less

Differential modulation of degradative and repair responses of interleukin-1-treated chondrocytes by platelet-derived growth factor.

PubMed Central

Harvey, A K; Stack, S T; Chandrasekhar, S

1993-01-01

Interleukin 1 (IL-1) plays a dual role in cartilage matrix degeneration by promoting extracellular proteinase action such as the matrix metalloproteinases (increased degradation) and by suppressing the synthesis of extracellular matrix molecules (inhibition of repair). Platelet-derived growth factor (PDGF) is a wound-healing hormone which is released along with IL-1 during the inflammatory response. Since previous studies have shown that PDGF enhances IL-1 alpha effects on metalloproteinase activity, in this report, we have examined whether PDGF modifies IL-1 beta effects on cartilage proteoglycan synthesis. Initially, we confirmed that rabbit articular chondrocytes treated with IL-1 beta + PDGF induced higher proteinase activity, in comparison with IL-1-treated cells. We further observed that the increased proteinase activity correlated with an increase in the synthesis of collagenase/stromelysin proteins and a corresponding increase in the steady-state mRNA levels for both the enzymes. Studies on IL-1 receptor expression suggested that PDGF caused an increase in IL-1 receptor expression which, by augmenting the IL-1 response, may have led to the increase in proteinase induction. Analysis of proteoglycan synthesis confirmed that IL-1 reduced the incorporation of sulphated proteoglycan, aggrecan, into the extracellular matrix of chondrocytes, whereas PDGF stimulated it. However, cells treated with IL-1 + PDGF synthesized normal levels of aggrecan. This is in contrast with cells treated with IL-1 + fibroblast growth factor, in which case only proteinase activity was potentiated. The results allow us to conclude that (a) the two effector functions that play a role in matrix remodelling, namely matrix lysis (proteinase induction) and matrix repair (proteoglycan synthesis), occur via distinct pathways and (b) PDGF may play a crucial role in cartilage repair by initially causing matrix degradation followed by promoting new matrix synthesis. Images Figure 1 Figure 2 Figure 5 Figure 6 PMID:8503839

Expression of extracellular matrix metalloproteinase inducer in odontogenic cysts.

PubMed

Ali, Mohammad Abdulhadi Abbas

2008-08-01

Extracellular matrix metalloproteinase inducer (EMMPRIN) is known to induce matrix metalloproteinase (MMP) production. The expression of EMMPRIN in odontogenic cysts has not been previously studied. This study was done to determine the presence and the variability of EMMPRIN expression in various types of odontogenic cysts. An immunohistochemical study using a polyclonal anti-EMMPRIN antibody was done using 48 odontogenic cyst cases: 13 odontogenic keratocysts (OKCs), 18 dentigerous cysts (DCs), and 17 periapical cysts (PAs). Twelve cases of normal dental follicles (DFs) were also included in this study for comparison. EMMPRIN immunoreactivity was detected in all of the cysts and DFs studied. In odontogenic cysts, EMMPRIN immunoreactivity was generally higher in basal cells than in suprabasal cells. The overall EMMPRIN expression in the epithelial lining of the 3 different types of odontogenic cyst was significantly higher than in the DFs. Overall EMMPRIN expression was also found to be significantly higher in the epithelial lining of OKCs than in the other types of cysts. This study confirmed that EMMPRIN is present in odontogenic cysts and DFs. The higher EMMPRIN expression in OKCs suggests that it may be involved in the aggressive behavior of this type of cyst.

Auto-Bäcklund transformations for a matrix partial differential equation

NASA Astrophysics Data System (ADS)

Gordoa, P. R.; Pickering, A.

2018-07-01

We derive auto-Bäcklund transformations, analogous to those of the matrix second Painlevé equation, for a matrix partial differential equation. We also then use these auto-Bäcklund transformations to derive matrix equations involving shifts in a discrete variable, a process analogous to the use of the auto-Bäcklund transformations of the matrix second Painlevé equation to derive a discrete matrix first Painlevé equation. The equations thus derived then include amongst other examples a semidiscrete matrix equation which can be considered to be an extension of this discrete matrix first Painlevé equation. The application of this technique to the auto-Bäcklund transformations of the scalar case of our partial differential equation has not been considered before, and so the results obtained here in this scalar case are also new. Other equations obtained here using this technique include a scalar semidiscrete equation which arises in the case of the second Painlevé equation, and which does not seem to have been thus derived previously.

Creeping attachment after 10 years of treatment of a gingival recession with acellular dermal matrix: a case report.

PubMed

Santos, Antonio; Goumenos, George; Pascual, Andrés; Nart, Jose

2011-02-01

Acellular dermal matrix grafts have become a good alternative to autogenous soft tissue grafts in root coverage. Until now, the literature has reported short- or medium-term data regarding the stability of the gingival margin after the use of acellular dermal matrix on root coverage. The aim of this article is to describe a case report with 10 years of evolution with creeping attachment that developed bucally on a moderate recession of a maxillary canine with an old composite restoration subsequent to an acellular dermal matrix. Long-term creeping attachment and complete root coverage on a restored tooth treated with acellular dermal matrix has not been previously reported in the dental literature.

Matrix quality and disturbance frequency drive evolution of species behavior at habitat boundaries.

PubMed

Martin, Amanda E; Fahrig, Lenore

2015-12-01

Previous theoretical studies suggest that a species' landscape should influence the evolution of its dispersal characteristics, because landscape structure affects the costs and benefits of dispersal. However, these studies have not considered the evolution of boundary crossing, that is, the tendency of animals to cross from habitat to nonhabitat ("matrix"). It is important to understand this dispersal behavior, because of its effects on the probability of population persistence. Boundary-crossing behavior drives the rate of interaction with matrix, and thus, it influences the rate of movement among populations and the risk of dispersal mortality. We used an individual-based, spatially explicit model to simulate the evolution of boundary crossing in response to landscape structure. Our simulations predict higher evolved probabilities of boundary crossing in landscapes with more habitat, less fragmented habitat, higher-quality matrix, and more frequent disturbances (i.e., fewer generations between local population extinction events). Unexpectedly, our simulations also suggest that matrix quality and disturbance frequency have much stronger effects on the evolution of boundary crossing than either habitat amount or habitat fragmentation. Our results suggest that boundary-crossing responses are most affected by the costs of dispersal through matrix and the benefits of escaping local extinction events. Evolution of optimal behavior at habitat boundaries in response to the landscape may have implications for species in human-altered landscapes, because this behavior may become suboptimal if the landscape changes faster than the species' evolutionary response to that change. Understanding how matrix quality and habitat disturbance drive evolution of behavior at boundaries, and how this in turn influences the extinction risk of species in human-altered landscapes should help us identify species of conservation concern and target them for management.

Comprehensive T-matrix Reference Database: A 2009-2011 Update

NASA Technical Reports Server (NTRS)

Zakharova, Nadezhda T.; Videen, G.; Khlebtsov, Nikolai G.

2012-01-01

The T-matrix method is one of the most versatile and efficient theoretical techniques widely used for the computation of electromagnetic scattering by single and composite particles, discrete random media, and particles in the vicinity of an interface separating two half-spaces with different refractive indices. This paper presents an update to the comprehensive database of peer-reviewed T-matrix publications compiled by us previously and includes the publications that appeared since 2009. It also lists several earlier publications not included in the original database.

A genome-wide association study for clinical mastitis in first parity US Holstein cows using a single-step approach and a genomic matrix re-weighting procedure

USDA-ARS?s Scientific Manuscript database

Clinical mastitis (CM) is one of the health disorders with largest impacts on dairy farming profitability and animal welfare. Previous studies have consistently shown that CM is under genetic control but knowledge about regions of the genome associated with resistance to CM in US Holstein is lacking...

Structural Requirements For Bone Sialoprotein Binding And Modulation Of Matrix Metalloproteinase-2

PubMed Central

Jain, Alka; Karadag, Abdullah; Fisher, Larry W.; Fedarko, Neal S.

2008-01-01

Bone sialoprotein (BSP) has been shown to induce limited gelatinase activity in latent matrix metalloproteinase-2 (MMP-2) without removal of the propeptide and to restore enzymatic activity to MMP-2 previously inhibited by tissue inhibitor of matrix metalloproteinase-2 (TIMP2). The current study identifies structural domains in human BSP and MMP-2 that contribute to these interactions. The 26 amino acid domain encoded by exon 4 of BSP is shown by a series of binding and activity assays to be involved in the displacement of MMP-2′s propeptide from the active site and thereby inducing the protease activity. Binding assays in conjunction with enzyme activity assays demonstrate that both amino- and carboxy-terminal domains of BSP contribute to restoration of activity to TIMP2-inhibited MMP-2, while the MMP-2 hemopexin domain is not required for reactivation. PMID:18729384

Structural requirements for bone sialoprotein binding and modulation of matrix metalloproteinase-2.

PubMed

Jain, Alka; Karadag, Abdullah; Fisher, Larry W; Fedarko, Neal S

2008-09-23

Bone sialoprotein (BSP) has been shown to induce limited gelatinase activity in latent matrix metalloproteinase-2 (MMP-2) without removal of the propeptide and to restore enzymatic activity to MMP-2 previously inhibited by tissue inhibitor of matrix metalloproteinase-2 (TIMP2). The current study identifies structural domains in human BSP and MMP-2 that contribute to these interactions. The 26 amino acid domain encoded by exon 4 of BSP is shown by a series of binding and activity assays to be involved in the displacement of MMP-2's propeptide from the active site and thereby inducing the protease activity. Binding assays in conjunction with enzyme activity assays demonstrate that both amino- and carboxy-terminal domains of BSP contribute to restoration of activity to TIMP2-inhibited MMP-2, while the MMP-2 hemopexin domain is not required for reactivation.

Implementation of Laminate Theory Into Strain Rate Dependent Micromechanics Analysis of Polymer Matrix Composites

NASA Technical Reports Server (NTRS)

Goldberg, Robert K.

2000-01-01

A research program is in progress to develop strain rate dependent deformation and failure models for the analysis of polymer matrix composites subject to impact loads. Previously, strain rate dependent inelastic constitutive equations developed to model the polymer matrix were implemented into a mechanics of materials based micromechanics method. In the current work, the computation of the effective inelastic strain in the micromechanics model was modified to fully incorporate the Poisson effect. The micromechanics equations were also combined with classical laminate theory to enable the analysis of symmetric multilayered laminates subject to in-plane loading. A quasi-incremental trapezoidal integration method was implemented to integrate the constitutive equations within the laminate theory. Verification studies were conducted using an AS4/PEEK composite using a variety of laminate configurations and strain rates. The predicted results compared well with experimentally obtained values.

Optimal experimental designs for fMRI when the model matrix is uncertain.

PubMed

Kao, Ming-Hung; Zhou, Lin

2017-07-15

This study concerns optimal designs for functional magnetic resonance imaging (fMRI) experiments when the model matrix of the statistical model depends on both the selected stimulus sequence (fMRI design), and the subject's uncertain feedback (e.g. answer) to each mental stimulus (e.g. question) presented to her/him. While practically important, this design issue is challenging. This mainly is because that the information matrix cannot be fully determined at the design stage, making it difficult to evaluate the quality of the selected designs. To tackle this challenging issue, we propose an easy-to-use optimality criterion for evaluating the quality of designs, and an efficient approach for obtaining designs optimizing this criterion. Compared with a previously proposed method, our approach requires a much less computing time to achieve designs with high statistical efficiencies. Copyright © 2017 Elsevier Inc. All rights reserved.

Functional role of EMMPRIN in the formation and mineralisation of dental matrix in mouse molars.

PubMed

Xie, Ming; Xing, Guofang; Hou, Liwen; Bao, Jing; Chen, Yuqing; Jiao, Ting; Zhang, Fuqiang

2015-02-01

Our previous research has shown that the extracellular matrix metalloproteinase inducer (EMMPRIN) is expressed during and may function in the early development of tooth germs. In the present study, we observed the specific expression of EMMPRIN in ameloblasts and odontoblasts during the middle and late stages of tooth germ development using immunohistochemistry. Furthermore, to extend our understanding of the function of EMMPRIN in odontogenesis, we used an anti-EMMPRIN function-blocking antibody to remove EMMPRIN activity in tooth germ culture in vitro. Both the formation and mineralisation of dental hard tissues were suppressed in the tooth germ culture after the abrogation of EMMPRIN. Meanwhile, significant reductions in VEGF, MMP-9, ALPL, ameloblastin, amelogenin and enamelin expression were observed in antibody-treated tooth germ explants compared to control and normal serum-treated explants. The current results illustrate that EMMPRIN may play a critical role in the processing and maturation of the dental matrix.

Enhancing interacting residue prediction with integrated contact matrix prediction in protein-protein interaction.

PubMed

Du, Tianchuan; Liao, Li; Wu, Cathy H

2016-12-01

Identifying the residues in a protein that are involved in protein-protein interaction and identifying the contact matrix for a pair of interacting proteins are two computational tasks at different levels of an in-depth analysis of protein-protein interaction. Various methods for solving these two problems have been reported in the literature. However, the interacting residue prediction and contact matrix prediction were handled by and large independently in those existing methods, though intuitively good prediction of interacting residues will help with predicting the contact matrix. In this work, we developed a novel protein interacting residue prediction system, contact matrix-interaction profile hidden Markov model (CM-ipHMM), with the integration of contact matrix prediction and the ipHMM interaction residue prediction. We propose to leverage what is learned from the contact matrix prediction and utilize the predicted contact matrix as "feedback" to enhance the interaction residue prediction. The CM-ipHMM model showed significant improvement over the previous method that uses the ipHMM for predicting interaction residues only. It indicates that the downstream contact matrix prediction could help the interaction site prediction.

Mueller matrix microscope: a quantitative tool to facilitate detections and fibrosis scorings of liver cirrhosis and cancer tissues.

PubMed

Wang, Ye; He, Honghui; Chang, Jintao; He, Chao; Liu, Shaoxiong; Li, Migao; Zeng, Nan; Wu, Jian; Ma, Hui

2016-07-01

Today the increasing cancer incidence rate is becoming one of the biggest threats to human health.Among all types of cancers, liver cancer ranks in the top five in both frequency and mortality rate all over the world. During the development of liver cancer, fibrosis often evolves as part of a healing process in response to liver damage, resulting in cirrhosis of liver tissues. In a previous study, we applied the Mueller matrix microscope to pathological liver tissue samples and found that both the Mueller matrix polar decomposition (MMPD) and Mueller matrix transformation (MMT) parameters are closely related to the fibrous microstructures. In this paper,we take this one step further to quantitatively facilitate the fibrosis detections and scorings of pathological liver tissue samples in different stages from cirrhosis to cancer using the Mueller matrix microscope. The experimental results of MMPD and MMT parameters for the fibrotic liver tissue samples in different stages are measured and analyzed. We also conduct Monte Carlo simulations based on the sphere birefringence model to examine in detail the influence of structural changes in different fibrosis stages on the imaging parameters. Both the experimental and simulated results indicate that the polarized light microscope and transformed Mueller matrix parameter scan provide additional quantitative information helpful for fibrosis detections and scorings of liver cirrhosis and cancers. Therefore, the polarized light microscope and transformed Mueller matrix parameters have a good application prospect in liver cancer diagnosis.

Mueller matrix microscope: a quantitative tool to facilitate detections and fibrosis scorings of liver cirrhosis and cancer tissues

NASA Astrophysics Data System (ADS)

Wang, Ye; He, Honghui; Chang, Jintao; He, Chao; Liu, Shaoxiong; Li, Migao; Zeng, Nan; Wu, Jian; Ma, Hui

2016-07-01

Today the increasing cancer incidence rate is becoming one of the biggest threats to human health. Among all types of cancers, liver cancer ranks in the top five in both frequency and mortality rate all over the world. During the development of liver cancer, fibrosis often evolves as part of a healing process in response to liver damage, resulting in cirrhosis of liver tissues. In a previous study, we applied the Mueller matrix microscope to pathological liver tissue samples and found that both the Mueller matrix polar decomposition (MMPD) and Mueller matrix transformation (MMT) parameters are closely related to the fibrous microstructures. In this paper, we take this one step further to quantitatively facilitate the fibrosis detections and scorings of pathological liver tissue samples in different stages from cirrhosis to cancer using the Mueller matrix microscope. The experimental results of MMPD and MMT parameters for the fibrotic liver tissue samples in different stages are measured and analyzed. We also conduct Monte Carlo simulations based on the sphere birefringence model to examine in detail the influence of structural changes in different fibrosis stages on the imaging parameters. Both the experimental and simulated results indicate that the polarized light microscope and transformed Mueller matrix parameters can provide additional quantitative information helpful for fibrosis detections and scorings of liver cirrhosis and cancers. Therefore, the polarized light microscope and transformed Mueller matrix parameters have a good application prospect in liver cancer diagnosis.

Acausal measurement-based quantum computing

NASA Astrophysics Data System (ADS)

Morimae, Tomoyuki

2014-07-01

In measurement-based quantum computing, there is a natural "causal cone" among qubits of the resource state, since the measurement angle on a qubit has to depend on previous measurement results in order to correct the effect of by-product operators. If we respect the no-signaling principle, by-product operators cannot be avoided. Here we study the possibility of acausal measurement-based quantum computing by using the process matrix framework [Oreshkov, Costa, and Brukner, Nat. Commun. 3, 1092 (2012), 10.1038/ncomms2076]. We construct a resource process matrix for acausal measurement-based quantum computing restricting local operations to projective measurements. The resource process matrix is an analog of the resource state of the standard causal measurement-based quantum computing. We find that if we restrict local operations to projective measurements the resource process matrix is (up to a normalization factor and trivial ancilla qubits) equivalent to the decorated graph state created from the graph state of the corresponding causal measurement-based quantum computing. We also show that it is possible to consider a causal game whose causal inequality is violated by acausal measurement-based quantum computing.

Interaction of formic acid with nitrogen: stabilization of the higher-energy conformer.

PubMed

Marushkevich, Kseniya; Räsänen, Markku; Khriachtchev, Leonid

2010-10-07

Conformational change is an important concept in chemistry and physics. In the present work, we study conformations of formic acid (HCOOH, FA) and report the preparation and identification of the complex of the higher-energy conformer cis-FA with N(2) in an argon matrix. The cis-FA···N(2) complex was synthesized by combining annealing and vibrational excitation of the ground-state trans-FA in a FA/N(2)/Ar matrix. The assignment is based on IR spectroscopic measurements and ab initio calculations. The cis-FA···N(2) complex decay in an argon matrix is much slower compared with the cis-FA monomer. In agreement with the experimental observations, the calculations predict a substantial increase in the stabilization barrier for the cis-FA···N(2) complex compared with the uncomplexed cis-FA monomer. A number of solvation effects in an argon matrix are computationally estimated and discussed. The present results on the cis-FA···N(2) complex show that intermolecular interaction can stabilize intrinsically unstable conformers, as previously found for some other cis-FA complexes.

Inhibition of membrane type-1 matrix metalloproteinase by cancer drugs interferes with the homing of diabetogenic T cells into the pancreas.

PubMed

Savinov, Alexei Y; Rozanov, Dmitri V; Golubkov, Vladislav S; Wong, F Susan; Strongin, Alex Y

2005-07-29

We have discovered that clinically tested inhibitors of matrix metalloproteinases can control the functional activity of T cell membrane type-1 matrix metalloproteinase (MT1-MMP) and the onset of disease in a rodent model of type 1 diabetes in non-obese diabetic mice. We determined that MT1-MMP proteolysis of the T cell surface CD44 adhesion receptor affects the homing of T cells into the pancreas. We also determined that both the induction of the intrinsic T cell MT1-MMP activity and the shedding of cellular CD44 follow the adhesion of insulin-specific, CD8-positive, Kd-restricted T cells to the matrix. Conversely, inhibition of these events by AG3340 (a potent hydroxamate inhibitor that was widely used in clinical trials in cancer patents) impedes the transmigration of diabetogenic T cells into the pancreas and protects non-obese diabetic mice from diabetes onset. Overall, our studies have divulged a previously unknown function of MT1-MMP and identified a promising novel drug target in type I diabetes.

Efficient Implementation of the Invariant Imbedding T-Matrix Method and the Separation of Variables Method Applied to Large Nonspherical Inhomogeneous Particles

NASA Technical Reports Server (NTRS)

Bi, Lei; Yang, Ping; Kattawar, George W.; Mishchenko, Michael I.

2012-01-01

Three terms, ''Waterman's T-matrix method'', ''extended boundary condition method (EBCM)'', and ''null field method'', have been interchangeable in the literature to indicate a method based on surface integral equations to calculate the T-matrix. Unlike the previous method, the invariant imbedding method (IIM) calculates the T-matrix by the use of a volume integral equation. In addition, the standard separation of variables method (SOV) can be applied to compute the T-matrix of a sphere centered at the origin of the coordinate system and having a maximal radius such that the sphere remains inscribed within a nonspherical particle. This study explores the feasibility of a numerical combination of the IIM and the SOV, hereafter referred to as the IIMþSOV method, for computing the single-scattering properties of nonspherical dielectric particles, which are, in general, inhomogeneous. The IIMþSOV method is shown to be capable of solving light-scattering problems for large nonspherical particles where the standard EBCM fails to converge. The IIMþSOV method is flexible and applicable to inhomogeneous particles and aggregated nonspherical particles (overlapped circumscribed spheres) representing a challenge to the standard superposition T-matrix method. The IIMþSOV computational program, developed in this study, is validated against EBCM simulated spheroid and cylinder cases with excellent numerical agreement (up to four decimal places). In addition, solutions for cylinders with large aspect ratios, inhomogeneous particles, and two-particle systems are compared with results from discrete dipole approximation (DDA) computations, and comparisons with the improved geometric-optics method (IGOM) are found to be quite encouraging.

Nipah Virus C Protein Recruits Tsg101 to Promote the Efficient Release of Virus in an ESCRT-Dependent Pathway.

PubMed

Park, Arnold; Yun, Tatyana; Vigant, Frederic; Pernet, Olivier; Won, Sohui T; Dawes, Brian E; Bartkowski, Wojciech; Freiberg, Alexander N; Lee, Benhur

2016-05-01

The budding of Nipah virus, a deadly member of the Henipavirus genus within the Paramyxoviridae, has been thought to be independent of the host ESCRT pathway, which is critical for the budding of many enveloped viruses. This conclusion was based on the budding properties of the virus matrix protein in the absence of other virus components. Here, we find that the virus C protein, which was previously investigated for its role in antagonism of innate immunity, recruits the ESCRT pathway to promote efficient virus release. Inhibition of ESCRT or depletion of the ESCRT factor Tsg101 abrogates the C enhancement of matrix budding and impairs live Nipah virus release. Further, despite the low sequence homology of the C proteins of known henipaviruses, they all enhance the budding of their cognate matrix proteins, suggesting a conserved and previously unknown function for the henipavirus C proteins.

Observation of Transient Surface-Bound Intermediates by Interfacial Matrix Stabilization Spectroscopy (imss)

NASA Astrophysics Data System (ADS)

Jarrah, Nina K.; Moore, David T.

2014-06-01

Interfacial matrix stabilization spectroscopy is a new technique based on matrix isolation spectroscopy, but where a cryogenic matrix is deposited over the top of a film sample, in order to characterize interactions between the substrate and molecular dopants. The IMSS technique harnesses the well-established ability of cryogenic matrices to trap and stabilize transient species, although in this case it is applied to intermediates relevant to heterogeneous catalysis. In this proof-of-concept study, we present data for CO and O2 reactants binding to TiO2 and Au/TiO2 nanoparticle films, where in the latter case the Au nanoparticles were created by de-wetting of a 22.5 nm overlayer at 450 K. The films are first pre-saturated with CO at 40 K, then cooled to 20 K, at which point an argon matrix is deposited over the top of them. The spectra are then annealed in stages over a range of temperatures between 20 and 40 K. In all cases, the presence of the Ar matrix alters the appearance of the CO bands, revealing additional structure, such as a broad feature at 2150 wn, which is typically attributed to CO interacting with OH groups on the TiO2 surface, but is not observed at 40 K for these samples in the absence of the matrix. The interpretation is that the matrix induces a caging-effect that prevents molecules from desorbing from weak binding sites from which they would be "pumped away" in the vacuum chamber if the matrix were not present. Perhaps the most interesting feature of these spectra is a small but sharp band at 2112 wn that appears ONLY when O2 is added to the argon matrix as a dopant. This transient band grows in following annealing at 32 K, but then disappears upon annealing above 34 K, suggesting that it may correspond to a reactive intermediate. The band occurs for samples both with and without Au present on the TiO2 surface, but shows a larger intensity in the latter case. Possible assignments for the observed band in light of previous studies from the literature will be discussed in detail.

Matrix metalloproteinases in exercise and obesity.

PubMed

Jaoude, Jonathan; Koh, Yunsuk

2016-01-01

Matrix metalloproteinases (MMPs) are zinc- and calcium-dependent endoproteinases that have the ability to break down extracellular matrix. The large range of MMPs' functions widens their spectrum of potential role as activators or inhibitors in tissue remodeling, cardiovascular diseases, and obesity. In particular, MMP-1, -2, and -9 may be associated with exercise and obesity. Thus, the current study reviewed the effects of different types of exercise (resistance and aerobic) on MMP-1, -2, and -9. Previous studies report that the response of MMP-2 and -9 to resistance exercise is dependent upon the length of exercise training, since long-term resistance exercise training increased both MMP-2 and -9, whereas acute bout of resistance exercise decreased these MMPs. Aerobic exercise produces an inconsistent result on MMPs, although some studies showed a decrease in MMP-1. Obesity is related to a relatively lower level of MMP-9, indicating that an exercise-induced increase in MMP-9 may positively influence obesity. A comprehensive understanding of the relationship between exercise, obesity, and MMPs does not exist yet. Future studies examining the acute and chronic responses of these MMPs using different subject models may provide a better understanding of the molecular mechanisms that are associated with exercise, obesity, and cardiovascular disease.

Local effect of zoledronic acid on new bone formation in posterolateral spinal fusion with demineralized bone matrix in a murine model.

PubMed

Zwolak, Pawel; Farei-Campagna, Jan; Jentzsch, Thorsten; von Rechenberg, Brigitte; Werner, Clément M

2018-01-01

Posterolateral spinal fusion is a common orthopaedic surgery performed to treat degenerative and traumatic deformities of the spinal column. In posteriolateral spinal fusion, different osteoinductive demineralized bone matrix products have been previously investigated. We evaluated the effect of locally applied zoledronic acid in combination with commercially available demineralized bone matrix putty on new bone formation in posterolateral spinal fusion in a murine in vivo model. A posterolateral sacral spine fusion in murine model was used to evaluate the new bone formation. We used the sacral spine fusion model to model the clinical situation in which a bone graft or demineralized bone matrix is applied after dorsal instrumentation of the spine. In our study, group 1 received decortications only (n = 10), group 2 received decortication, and absorbable collagen sponge carrier, group 3 received decortication and absorbable collagen sponge carrier with zoledronic acid in dose 10 µg, group 4 received demineralized bone matrix putty (DBM putty) plus decortication (n = 10), and group 5 received DBM putty, decortication and locally applied zoledronic acid in dose 10 µg. Imaging was performed using MicroCT for new bone formation assessment. Also, murine spines were harvested for histopathological analysis 10 weeks after surgery. The surgery performed through midline posterior approach was reproducible. In group with decortication alone there was no new bone formation. Application of demineralized bone matrix putty alone produced new bone formation which bridged the S1-S4 laminae. Local application of zoledronic acid to demineralized bone matrix putty resulted in significant increase of new bone formation as compared to demineralized bone matrix putty group alone. A single local application of zoledronic acid with DBM putty during posterolateral fusion in sacral murine spine model increased significantly new bone formation in situ in our model. Therefore, our results justify further investigations to potentially use local application of zoledronic acid in future clinical studies.

Finite-time scaling at the Anderson transition for vibrations in solids

NASA Astrophysics Data System (ADS)

Beltukov, Y. M.; Skipetrov, S. E.

2017-11-01

A model in which a three-dimensional elastic medium is represented by a network of identical masses connected by springs of random strengths and allowed to vibrate only along a selected axis of the reference frame exhibits an Anderson localization transition. To study this transition, we assume that the dynamical matrix of the network is given by a product of a sparse random matrix with real, independent, Gaussian-distributed nonzero entries and its transpose. A finite-time scaling analysis of the system's response to an initial excitation allows us to estimate the critical parameters of the localization transition. The critical exponent is found to be ν =1.57 ±0.02 , in agreement with previous studies of the Anderson transition belonging to the three-dimensional orthogonal universality class.

An efficient matrix product operator representation of the quantum chemical Hamiltonian

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

Keller, Sebastian, E-mail: sebastian.keller@phys.chem.ethz.ch; Reiher, Markus, E-mail: markus.reiher@phys.chem.ethz.ch; Dolfi, Michele, E-mail: dolfim@phys.ethz.ch

We describe how to efficiently construct the quantum chemical Hamiltonian operator in matrix product form. We present its implementation as a density matrix renormalization group (DMRG) algorithm for quantum chemical applications. Existing implementations of DMRG for quantum chemistry are based on the traditional formulation of the method, which was developed from the point of view of Hilbert space decimation and attained higher performance compared to straightforward implementations of matrix product based DMRG. The latter variationally optimizes a class of ansatz states known as matrix product states, where operators are correspondingly represented as matrix product operators (MPOs). The MPO construction schememore » presented here eliminates the previous performance disadvantages while retaining the additional flexibility provided by a matrix product approach, for example, the specification of expectation values becomes an input parameter. In this way, MPOs for different symmetries — abelian and non-abelian — and different relativistic and non-relativistic models may be solved by an otherwise unmodified program.« less

New infinite-dimensional hidden symmetries for heterotic string theory

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

Gao Yajun

The symmetry structures of two-dimensional heterotic string theory are studied further. A (2d+n)x(2d+n) matrix complex H-potential is constructed and the field equations are extended into a complex matrix formulation. A pair of Hauser-Ernst-type linear systems are established. Based on these linear systems, explicit formulations of new hidden symmetry transformations for the considered theory are given and then these symmetry transformations are verified to constitute infinite-dimensional Lie algebras: the semidirect product of the Kac-Moody o(d,d+n-circumflex) and Virasoro algebras (without center charges). These results demonstrate that the heterotic string theory under consideration possesses more and richer symmetry structures than previously expected.

Effects of osmotic pressure in the extracellular matrix on tissue deformation.

PubMed

Lu, Y; Parker, K H; Wang, W

2006-06-15

In soft tissues, large molecules such as proteoglycans trapped in the extracellular matrix (ECM) generate high levels of osmotic pressure to counter-balance external pressures. The semi-permeable matrix and fixed negative charges on these molecules serve to promote the swelling of tissues when there is an imbalance of molecular concentrations. Structural molecules, such as collagen fibres, form a network of stretch-resistant matrix, which prevents tissue from over-swelling and keeps tissue integrity. However, collagen makes little contribution to load bearing; the osmotic pressure in the ECM is the main contributor balancing external pressures. Although there have been a number of studies on tissue deformation, there is no rigorous analysis focusing on the contribution of the osmotic pressure in the ECM on the viscoelastic behaviour of soft tissues. Furthermore, most previous works were carried out based on the assumption of infinitesimal deformation, whereas tissue deformation is finite under physiological conditions. In the current study, a simplified mathematical model is proposed. Analytic solutions for solute distribution in the ECM and the free-moving boundary were derived by solving integro-differential equations under constant and dynamic loading conditions. Osmotic pressure in the ECM is found to contribute significantly to the viscoelastic characteristics of soft tissues during their deformation.

Fibrin matrix for suspension of regenerative cells in an artificial nerve conduit.

PubMed

Kalbermatten, D F; Kingham, P J; Mahay, D; Mantovani, C; Pettersson, J; Raffoul, W; Balcin, H; Pierer, G; Terenghi, G

2008-06-01

Peripheral nerve injury presents with specific problems of neuronal reconstructions, and from a clinical viewpoint a tissue engineering approach would facilitate the process of repair and regeneration. We have previously used artificial nerve conduits made from bioresorbable poly-3-hydroxybutyrate (PHB) in order to refine the ways in which peripheral nerves are repaired and reconnected to the target muscles and skin. The addition of Schwann cells (SC) or differentiated mesenchymal stem cells (dMSC) to the conduits enhances regeneration. In this study, we have used a matrix based on fibrin (Tisseel) to fill optimally the nerve-conduits with cells. In vitro analysis showed that both SC and MSC adhered significantly better to PHB in the presence of fibrin and cells continued to maintain their differentiated state. Cells were more optimally distributed throughout the conduit when seeded in fibrin than by delivery in growth medium alone. Transplantation of the nerve conduits in vivo showed that cells in combination with fibrin matrix significantly increased nerve regeneration distance (using PGP9.5 and S100 distal and proximal immunohistochemistry) when compared with empty PHB conduits. This study shows the beneficial combinatory effect of an optimised matrix, cells and conduit material as a step towards bridging nerve gaps which should ultimately lead to improved functional recovery following nerve injury.

Multispectral Palmprint Recognition Using a Quaternion Matrix

PubMed Central

Xu, Xingpeng; Guo, Zhenhua; Song, Changjiang; Li, Yafeng

2012-01-01

Palmprints have been widely studied for biometric recognition for many years. Traditionally, a white light source is used for illumination. Recently, multispectral imaging has drawn attention because of its high recognition accuracy. Multispectral palmprint systems can provide more discriminant information under different illuminations in a short time, thus they can achieve better recognition accuracy. Previously, multispectral palmprint images were taken as a kind of multi-modal biometrics, and the fusion scheme on the image level or matching score level was used. However, some spectral information will be lost during image level or matching score level fusion. In this study, we propose a new method for multispectral images based on a quaternion model which could fully utilize the multispectral information. Firstly, multispectral palmprint images captured under red, green, blue and near-infrared (NIR) illuminations were represented by a quaternion matrix, then principal component analysis (PCA) and discrete wavelet transform (DWT) were applied respectively on the matrix to extract palmprint features. After that, Euclidean distance was used to measure the dissimilarity between different features. Finally, the sum of two distances and the nearest neighborhood classifier were employed for recognition decision. Experimental results showed that using the quaternion matrix can achieve a higher recognition rate. Given 3000 test samples from 500 palms, the recognition rate can be as high as 98.83%. PMID:22666049

Multispectral palmprint recognition using a quaternion matrix.

PubMed

Xu, Xingpeng; Guo, Zhenhua; Song, Changjiang; Li, Yafeng

2012-01-01

Palmprints have been widely studied for biometric recognition for many years. Traditionally, a white light source is used for illumination. Recently, multispectral imaging has drawn attention because of its high recognition accuracy. Multispectral palmprint systems can provide more discriminant information under different illuminations in a short time, thus they can achieve better recognition accuracy. Previously, multispectral palmprint images were taken as a kind of multi-modal biometrics, and the fusion scheme on the image level or matching score level was used. However, some spectral information will be lost during image level or matching score level fusion. In this study, we propose a new method for multispectral images based on a quaternion model which could fully utilize the multispectral information. Firstly, multispectral palmprint images captured under red, green, blue and near-infrared (NIR) illuminations were represented by a quaternion matrix, then principal component analysis (PCA) and discrete wavelet transform (DWT) were applied respectively on the matrix to extract palmprint features. After that, Euclidean distance was used to measure the dissimilarity between different features. Finally, the sum of two distances and the nearest neighborhood classifier were employed for recognition decision. Experimental results showed that using the quaternion matrix can achieve a higher recognition rate. Given 3000 test samples from 500 palms, the recognition rate can be as high as 98.83%.

Flax Fiber Hydrophobic Extract Inhibits Human Skin Cells Inflammation and Causes Remodeling of Extracellular Matrix and Wound Closure Activation

PubMed Central

Styrczewska, Monika; Kostyn, Anna; Kulma, Anna; Majkowska-Skrobek, Grazyna; Augustyniak, Daria; Prescha, Anna; Czuj, Tadeusz; Szopa, Jan

2015-01-01

Inflammation is the basis of many diseases, with chronic wounds amongst them, limiting cell proliferation and tissue regeneration. Our previous preclinical study of flax fiber applied as a wound dressing and analysis of its components impact on the fibroblast transcriptome suggested flax fiber hydrophobic extract use as an anti-inflammatory and wound healing preparation. The extract contains cannabidiol (CBD), phytosterols, and unsaturated fatty acids, showing great promise in wound healing. In in vitro proliferation and wound closure tests the extract activated cell migration and proliferation. The activity of matrix metalloproteinases in skin cells was increased, suggesting activation of extracellular components remodeling. The expression of cytokines was diminished by the extract in a cannabidiol-dependent manner, but β-sitosterol can act synergistically with CBD in inflammation inhibition. Extracellular matrix related genes were also analyzed, considering their importance in further stages of wound healing. The extract activated skin cell matrix remodeling, but the changes were only partially cannabidiol- and β-sitosterol-dependent. The possible role of fatty acids also present in the extract is suggested. The study shows the hydrophobic flax fiber components as wound healing activators, with anti-inflammatory cannabidiol acting in synergy with sterols, and migration and proliferation promoting agents, some of which still require experimental identification. PMID:26347154

Formation of bone-like mineralized matrix by periodontal ligament cells in vivo: a morphological study in rats.

PubMed

Hiraga, Toru; Ninomiya, Tadashi; Hosoya, Akihiro; Takahashi, Masafumi; Nakamura, Hiroaki

2009-01-01

Periodontal ligament (PDL) is a unique connective tissue that not only connects cementum and alveolar bone to support teeth, but also plays an important role in reconstructing periodontal tissues. Previous studies have suggested that PDL cells have osteogenic potential; however, they lack precise histological examinations. Here, we studied bone-like matrix formation by PDL cells in rats using morphological techniques. Rat and human PDL cells exhibited substantial alkaline phosphatase activity and induced mineralization in vitro. RT-PCR analyses showed that PDL cells expressed the osteoblast markers, Runx2, osterix, and osteocalcin. These results suggest that PDL cells share similar phenotypes with osteoblasts. To examine the bone-like matrix formation in vivo, PDL cells isolated from green fluorescent protein (GFP)-transgenic rats were inoculated with hydroxyapatite (HA) disks into wild-type rats. Five weeks after the implantation, the pores in HA disks were occupied by GFP-positive cells. Mineralized matrix formation was also found on the surface of HA pores. At 12 weeks, some of the pores were filled with bone-like mineralized matrices (BLMM), which were positive for the bone matrix proteins, osteopontin, bone sialoprotein, and osteocalcin. Immunohistochemical examination revealed that most of the osteoblast- and osteocyte-like cells on or in the BLMM were GFP-positive, suggesting that the BLMM were directly formed by the inoculated PDL cells. On the pore surfaces, Sharpey's fiber-like structures embedded in cementum-like mineralized layers were also observed. These results collectively suggest that PDL cells have the ability to form periodontal tissues and could be a useful source for regenerative therapies of periodontal diseases.

Past matrix stiffness primes epithelial cells and regulates their future collective migration through a mechanical memory.

PubMed

Nasrollahi, Samila; Walter, Christopher; Loza, Andrew J; Schimizzi, Gregory V; Longmore, Gregory D; Pathak, Amit

2017-11-01

During morphogenesis and cancer metastasis, grouped cells migrate through tissues of dissimilar stiffness. Although the influence of matrix stiffness on cellular mechanosensitivity and motility are well-recognized, it remains unknown whether these matrix-dependent cellular features persist after cells move to a new microenvironment. Here, we interrogate whether priming of epithelial cells by a given matrix stiffness influences their future collective migration on a different matrix - a property we refer to as the 'mechanical memory' of migratory cells. To prime cells on a defined matrix and track their collective migration onto an adjoining secondary matrix of dissimilar stiffness, we develop a modular polyacrylamide substrate through step-by-step polymerization of different PA compositions. We report that epithelial cells primed on a stiff matrix migrate faster, display higher actomyosin expression, form larger focal adhesions, and retain nuclear YAP even after arriving onto a soft secondary matrix, as compared to their control behavior on a homogeneously soft matrix. Priming on a soft ECM causes a reverse effect. The depletion of YAP dramatically reduces this memory-dependent migration. Our results present a previously unidentified regulation of mechanosensitive collective cell migration by past matrix stiffness, in which mechanical memory depends on YAP activity. Copyright © 2017 Elsevier Ltd. All rights reserved.

Tracking Time Evolution of Collective Attention Clusters in Twitter: Time Evolving Nonnegative Matrix Factorisation.

PubMed

Saito, Shota; Hirata, Yoshito; Sasahara, Kazutoshi; Suzuki, Hideyuki

2015-01-01

Micro-blogging services, such as Twitter, offer opportunities to analyse user behaviour. Discovering and distinguishing behavioural patterns in micro-blogging services is valuable. However, it is difficult and challenging to distinguish users, and to track the temporal development of collective attention within distinct user groups in Twitter. In this paper, we formulate this problem as tracking matrices decomposed by Nonnegative Matrix Factorisation for time-sequential matrix data, and propose a novel extension of Nonnegative Matrix Factorisation, which we refer to as Time Evolving Nonnegative Matrix Factorisation (TENMF). In our method, we describe users and words posted in some time interval by a matrix, and use several matrices as time-sequential data. Subsequently, we apply Time Evolving Nonnegative Matrix Factorisation to these time-sequential matrices. TENMF can decompose time-sequential matrices, and can track the connection among decomposed matrices, whereas previous NMF decomposes a matrix into two lower dimension matrices arbitrarily, which might lose the time-sequential connection. Our proposed method has an adequately good performance on artificial data. Moreover, we present several results and insights from experiments using real data from Twitter.

Comprehensive T-Matrix Reference Database: A 2007-2009 Update

NASA Technical Reports Server (NTRS)

Mishchenko, Michael I.; Zakharova, Nadia T.; Videen, Gorden; Khlebtsov, Nikolai G.; Wriedt, Thomas

2010-01-01

The T-matrix method is among the most versatile, efficient, and widely used theoretical techniques for the numerically exact computation of electromagnetic scattering by homogeneous and composite particles, clusters of particles, discrete random media, and particles in the vicinity of an interface separating two half-spaces with different refractive indices. This paper presents an update to the comprehensive database of T-matrix publications compiled by us previously and includes the publications that appeared since 2007. It also lists several earlier publications not included in the original database.

New method for propagating the square root covariance matrix in triangular form. [using Kalman-Bucy filter

NASA Technical Reports Server (NTRS)

Choe, C. Y.; Tapley, B. D.

1975-01-01

A method proposed by Potter of applying the Kalman-Bucy filter to the problem of estimating the state of a dynamic system is described, in which the square root of the state error covariance matrix is used to process the observations. A new technique which propagates the covariance square root matrix in lower triangular form is given for the discrete observation case. The technique is faster than previously proposed algorithms and is well-adapted for use with the Carlson square root measurement algorithm.

Polymer-mediated nanorod self-assembly predicted by dissipative particle dynamics simulations.

PubMed

Khani, Shaghayegh; Jamali, Safa; Boromand, Arman; Hore, Michael J A; Maia, Joao

2015-09-14

Self-assembly of nanoparticles in polymer matrices is an interesting and growing subject in the field of nanoscience and technology. We report herein on modelling studies of the self-assembly and phase behavior of nanorods in a homopolymer matrix, with the specific goal of evaluating the role of deterministic entropic and enthalpic factors that control the aggregation/dispersion in such systems. Grafting polymer brushes from the nanorods is one approach to control/impact their self-assembly capabilities within a polymer matrix. From an energetic point of view, miscible interactions between the brush and the matrix are required for achieving a better dispersibility; however, grafting density and brush length are the two important parameters in dictating the morphology. Unlike in previous computational studies, the present Dissipative Particle Dynamics (DPD) simulation framework is able to both predict dispersion or aggregation of nanorods and determine the self-assembled structure, allowing for the determination of a phase diagram, which takes all of these factors into account. Three types of morphologies are predicted: dispersion, aggregation and partial aggregation. Moreover, favorable enthalpic interactions between the brush and the matrix are found to be essential for expanding the window for achieving a well-dispersed morphology. A three-dimensional phase diagram is mapped on which all the afore-mentioned parameters are taken into account. Additionally, in the case of immiscibility between brushes and the matrix, simulations predict the formation of some new and tunable structures.

Scattering matrix approach to the dissociative recombination of HCO{sup +} and N{sub 2}H{sup +}

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

Fonseca dos Santos, S.; Douguet, N.; Orel, A. E.

We present a theoretical study of the indirect dissociative recombination of linear polyatomic ions at low collisional energies. The approach is based on the computation of the scattering matrix just above the ionization threshold and enables the explicit determination of all diabatic electronic couplings responsible for dissociative recombination. In addition, we use the multi-channel quantum-defect theory to demonstrate the precision of the scattering matrix by reproducing accurately ab initio Rydberg state energies of the neutral molecule. We consider the molecular ions N{sub 2}H{sup +} and HCO{sup +} as benchmark systems of astrophysical interest and improve former theoretical studies, which hadmore » repeatedly produced smaller cross sections than experimentally measured. Specifically, we demonstrate the crucial role of the previously overlooked stretching modes for linear polyatomic ions with large permanent dipole moment. The theoretical cross sections for both ions agree well with experimental data over a wide energy range. Finally, we consider the potential role of the HOC{sup +} isomer in the experimental cross sections of HCO{sup +} at energies below 10 meV.« less

A model to predict thermal conductivity of irradiated U-Mo dispersion fuel

NASA Astrophysics Data System (ADS)

Burkes, Douglas E.; Huber, Tanja K.; Casella, Andrew M.

2016-05-01

Numerous global programs are focused on the continued development of existing and new research and test reactor fuels to achieve maximum attainable uranium loadings to support the conversion of a number of the world's remaining high-enriched uranium fueled reactors to low-enriched uranium fuel. Some of these programs are focused on assisting with the development and qualification of a fuel design that consists of a uranium-molybdenum (U-Mo) alloy dispersed in an aluminum matrix as one option for reactor conversion. Thermal conductivity is an important consideration in determining the operational temperature of the fuel and can be influenced by interaction layer formation between the dispersed phase and matrix and upon the concentration of the dispersed phase within the matrix. This paper extends the use of a simple model developed previously to study the influence of interaction layer formation as well as the size and volume fraction of fuel particles dispersed in the matrix, Si additions to the matrix, and Mo concentration in the fuel particles on the effective thermal conductivity of the U-Mo/Al composite during irradiation. The model has been compared to experimental measurements recently conducted on U-Mo/Al dispersion fuels at two different fission densities with acceptable agreement. Observations of the modeled results indicate that formation of an interaction layer and subsequent consumption of the matrix reveals a rather significant effect on effective thermal conductivity. The modeled interaction layer formation and subsequent consumption of the high thermal conductivity matrix was sensitive to the average dispersed fuel particle size, suggesting this parameter as one of the most effective in minimizing thermal conductivity degradation of the composite, while the influence of Si additions to the matrix in the model was highly dependent upon irradiation conditions.

Identification and Characterization of the Lysine-Rich Matrix Protein Family in Pinctada fucata: Indicative of Roles in Shell Formation.

PubMed

Liang, Jian; Xie, Jun; Gao, Jing; Xu, Chao-Qun; Yan, Yi; Jia, Gan-Chu; Xiang, Liang; Xie, Li-Ping; Zhang, Rong-Qing

2016-12-01

Mantle can secret matrix proteins playing key roles in regulating the process of shell formation. The genes encoding lysine-rich matrix proteins (KRMPs) are one of the most highly expressed matrix genes in pearl oysters. However, the expression pattern of KRMPs is limited and the functions of them still remain unknown. In this study, we isolated and identified six new members of lysine-rich matrix proteins, rich in lysine, glycine and tyrosine, and all of them are basic matrix proteins. Combined with four members of the KRMPs previously reported, all these proteins can be divided into three subclasses according to the results of phylogenetic analyses: KRMP1-3 belong to subclass KPI, KRMP4-5 belong to KPII, and KRMP6-10 belong to KPIII. Three subcategories of lysine-rich matrix proteins are highly expressed in the D-phase, the larvae and adult mantle. Lysine-rich matrix proteins are involved in the shell repairing process and associated with the formation of the shell and pearl. What's more, they can cause abnormal shell growth after RNA interference. In detail, KPI subgroup was critical for the beginning formation of the prismatic layer; both KPII and KPIII subgroups participated in the formation of prismatic layer and nacreous layer. Compared with different temperatures and salinity stimulation treatments, the influence of changes in pH on KRMPs gene expression was the greatest. Recombinant KRMP7 significantly inhibited CaCO 3 precipitation, changed the morphology of calcite, and inhibited the growth of aragonite in vitro. Our results are beneficial to understand the functions of the KRMP genes during shell formation.

A model to predict thermal conductivity of irradiated U–Mo dispersion fuel

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

Burkes, Douglas E.; Huber, Tanja K.; Casella, Andrew M.

The Office of Materials Management and Minimization Reactor Conversion Program continues to develop existing and new research and test reactor fuels to achieve maximum attainable uranium loadings to support the conversion of a number of the world’s remaining high-enriched uranium fueled reactors to low-enriched uranium fuel. The program is focused on assisting with the development and qualification of a fuel design that consists of a uranium-molybdenum (U-Mo) alloy dispersed in an aluminum matrix as one option for reactor conversion. Thermal conductivity is an important consideration in determining the operational temperature of the fuel and can be influenced by interaction layermore » formation between the dispersed phase and matrix and upon the concentration of the dispersed phase within the matrix. This paper extends the use of a simple model developed previously to study the influence of interaction layer formation as well as the size and volume fraction of fuel particles dispersed in the matrix, Si additions to the matrix, and Mo concentration in the fuel particles on the effective thermal conductivity of the U-Mo/Al composite during irradiation. The model has been compared to experimental measurements recently conducted on U-Mo/Al dispersion fuels at two different fission densities with acceptable agreement. Observations of the modeled results indicate that formation of an interaction layer and subsequent consumption of the matrix reveals a rather significant effect on effective thermal conductivity. The modeled interaction layer formation and subsequent consumption of the high thermal conductivity matrix was sensitive to the average dispersed fuel particle size, suggesting this parameter as one of the most effective in minimizing thermal conductivity degradation of the composite, while the influence of Si additions to the matrix in the model was highly dependent upon irradiation conditions.« less

ISOCT study of collagen crosslinking of collagen in cancer models (Conference Presentation)

NASA Astrophysics Data System (ADS)

Spicer, Graham; Young, Scott T.; Yi, Ji; Shea, Lonnie D.; Backman, Vadim

2016-03-01

The role of extracellular matrix modification and signaling in cancer progression is an increasingly recognized avenue for the progression of the disease. Previous study of field effect carcinogenesis with Inverse Spectroscopic Optical Coherence Tomography (ISOCT) has revealed pronounced changes in the nanoscale-sensitive mass fractal dimension D measured from field effect tissue when compared to healthy tissue. However, the origin of this difference in tissue ultrastructure in field effect carcinogenesis has remained poorly understood. Here, we present findings supporting the idea that enzymatic crosslinking of the extracellular matrix is an effect that presents at the earliest stages of carcinogenesis. We use a model of collagen gel with crosslinking induced by lysyl oxidase (LOXL4) to recapitulate the difference in D previously reported from healthy and cancerous tissue biopsies. Furthermore, STORM imaging of this collagen gel model verifies the morphologic effects of enzymatic crosslinking at length scales as small as 40 nm, close to the previously reported lower length scale sensitivity threshold of 35 nm for ISOCT. Analysis of the autocorrelation function from STORM images of collagen gels and subsequent fitting to the Whittle-Matérn correlation function shows a similar effect of LOXL4 on D from collagen measured with ISOCT and STORM. We extend this to mass spectrometric study of tissue to directly measure concentrations of collagen crosslink residues. The validation of ISOCT as a viable tool for non-invasive rapid quantification of collagen ultrastructure lends it to study other physiological phenomena involving ECM restructuring such as atherosclerotic plaque screening or cervical ripening during pregnancy.

Improved dynamic MRI reconstruction by exploiting sparsity and rank-deficiency.

PubMed

Majumdar, Angshul

2013-06-01

In this paper we address the problem of dynamic MRI reconstruction from partially sampled K-space data. Our work is motivated by previous studies in this area that proposed exploiting the spatiotemporal correlation of the dynamic MRI sequence by posing the reconstruction problem as a least squares minimization regularized by sparsity and low-rank penalties. Ideally the sparsity and low-rank penalties should be represented by the l(0)-norm and the rank of a matrix; however both are NP hard penalties. The previous studies used the convex l(1)-norm as a surrogate for the l(0)-norm and the non-convex Schatten-q norm (0

Exploiting Symmetry on Parallel Architectures.

NASA Astrophysics Data System (ADS)

Stiller, Lewis Benjamin

1995-01-01

This thesis describes techniques for the design of parallel programs that solve well-structured problems with inherent symmetry. Part I demonstrates the reduction of such problems to generalized matrix multiplication by a group-equivariant matrix. Fast techniques for this multiplication are described, including factorization, orbit decomposition, and Fourier transforms over finite groups. Our algorithms entail interaction between two symmetry groups: one arising at the software level from the problem's symmetry and the other arising at the hardware level from the processors' communication network. Part II illustrates the applicability of our symmetry -exploitation techniques by presenting a series of case studies of the design and implementation of parallel programs. First, a parallel program that solves chess endgames by factorization of an associated dihedral group-equivariant matrix is described. This code runs faster than previous serial programs, and discovered it a number of results. Second, parallel algorithms for Fourier transforms for finite groups are developed, and preliminary parallel implementations for group transforms of dihedral and of symmetric groups are described. Applications in learning, vision, pattern recognition, and statistics are proposed. Third, parallel implementations solving several computational science problems are described, including the direct n-body problem, convolutions arising from molecular biology, and some communication primitives such as broadcast and reduce. Some of our implementations ran orders of magnitude faster than previous techniques, and were used in the investigation of various physical phenomena.

N-WASP and cortactin are involved in invadopodium-dependent chemotaxis to EGF in breast tumor cells

PubMed Central

DesMarais, Vera; Yamaguchi, Hideki; Oser, Matthew; Soon, Lilian; Mouneimne, Ghassan; Sarmiento, Corina; Eddy, Robert; Condeelis, John

2009-01-01

Metastatic mammary carcinoma cells, which have previously been observed to form mature, matrix degrading invadopodia on a thick ECM matrix, are able to form invadopodia with similar characteristics on glass without previously applied matrix. They form in response to EGF, and contain the usual invadopodium core proteins N-WASP, Arp2/3, cortactin, cofilin, and F-actin. The study of invadopodia on glass allows for higher resolution analysis including the use of total internal reflection microscopy and analysis of their relationship to other cell motility events, in particular, lamellipodium extension and chemotaxis toward an EGF gradient. Invadopodium formation on glass requires N-WASP and cortactin but not microtubules. In a gradient of EGF more invadopodia form on the side of the cells facing the source of EGF. In addition, depletion of N-WASP or cortactin, which blocks invadopodium fromation, inhibits chemotaxis of cells towards EGF. This appears to be a localized defect in chemotaxis since depletion of N-WASP or cortactin via siRNA had no effect on lamellipodium protrusion or barbed end generation at the lamellipodium's leading edge. Since chemotaxis to EGF by breast tumor cells is involved in metastasis, inhibiting N-WASP activity in breast tumor cells might prevent metastasis of tumor cells while not affecting chemotaxis-dependent innate immunity which depends on WASp function in macrophages. PMID:19373774

Arc spray fabrication of metal matrix composite monotape

NASA Technical Reports Server (NTRS)

Westfall, L. J. (Inventor)

1985-01-01

Arc metal spraying is used to spray liquid metal onto an array of high strength fibers that were previously wound onto a large drum contained inside a controlled atmosphere chamber. This chamber is first evacuated to remove gaseous contaminants and then backfilled with a neutral gas up to atmospheric pressure. This process is used to produce a large size metal matrix composite monotape.

An improved semi-implicit method for structural dynamics analysis

NASA Technical Reports Server (NTRS)

Park, K. C.

1982-01-01

A semi-implicit algorithm is presented for direct time integration of the structural dynamics equations. The algorithm avoids the factoring of the implicit difference solution matrix and mitigates the unacceptable accuracy losses which plagued previous semi-implicit algorithms. This substantial accuracy improvement is achieved by augmenting the solution matrix with two simple diagonal matrices of the order of the integration truncation error.

Impact of enhancin genes on potency of LdNPV in gypsy moth

Treesearch

Kelli Hoover; Jim McNeil; Alyssa Gendron; James. Slavicek

2011-01-01

Lymantria dispar nucleopolyhedrovirus (LdNPV) contains two enhancin genes (E1 and E2) encoding proteases that degrade key peritrophic matrix (PM) proteins, thereby promoting infection and mortality by the virus. In a previous study, gypsy moth larvae inoculated with LdNPV in which both E1 and E2 were deleted (double deletion virus) resulted in a non-...

The role of porous matrix in water flow regulation within a karst unsaturated zone: an integrated hydrogeophysical approach

NASA Astrophysics Data System (ADS)

Carrière, Simon D.; Chalikakis, Konstantinos; Danquigny, Charles; Davi, Hendrik; Mazzilli, Naomi; Ollivier, Chloé; Emblanch, Christophe

2016-11-01

Some portions of the porous rock matrix in the karst unsaturated zone (UZ) can contain large volumes of water and play a major role in water flow regulation. The essential results are presented of a local-scale study conducted in 2011 and 2012 above the Low Noise Underground Laboratory (LSBB - Laboratoire Souterrain à Bas Bruit) at Rustrel, southeastern France. Previous research revealed the geological structure and water-related features of the study site and illustrated the feasibility of specific hydrogeophysical measurements. In this study, the focus is on hydrodynamics at the seasonal and event timescales. Magnetic resonance sounding (MRS) measured a high water content (more than 10 %) in a large volume of rock. This large volume of water cannot be stored in fractures and conduits within the UZ. MRS was also used to measure the seasonal variation of water stored in the karst UZ. A process-based model was developed to simulate the effect of vegetation on groundwater recharge dynamics. In addition, electrical resistivity tomography (ERT) monitoring was used to assess preferential water pathways during a rain event. This study demonstrates the major influence of water flow within the porous rock matrix on the UZ hydrogeological functioning at both the local (LSBB) and regional (Fontaine de Vaucluse) scales. By taking into account the role of the porous matrix in water flow regulation, these findings may significantly improve karst groundwater hydrodynamic modelling, exploitation, and sustainable management.

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

Sechin, Ivan, E-mail: shnbuz@gmail.com, E-mail: zotov@mi.ras.ru; ITEP, B. Cheremushkinskaya Str. 25, Moscow 117218; Zotov, Andrei, E-mail: shnbuz@gmail.com, E-mail: zotov@mi.ras.ru

In this paper we propose versions of the associative Yang-Baxter equation and higher order R-matrix identities which can be applied to quantum dynamical R-matrices. As is known quantum non-dynamical R-matrices of Baxter-Belavin type satisfy this equation. Together with unitarity condition and skew-symmetry it provides the quantum Yang-Baxter equation and a set of identities useful for different applications in integrable systems. The dynamical R-matrices satisfy the Gervais-Neveu-Felder (or dynamical Yang-Baxter) equation. Relation between the dynamical and non-dynamical cases is described by the IRF (interaction-round-a-face)-Vertex transformation. An alternative approach to quantum (semi-)dynamical R-matrices and related quantum algebras was suggested by Arutyunov, Chekhov,more » and Frolov (ACF) in their study of the quantum Ruijsenaars-Schneider model. The purpose of this paper is twofold. First, we prove that the ACF elliptic R-matrix satisfies the associative Yang-Baxter equation with shifted spectral parameters. Second, we directly prove a simple relation of the IRF-Vertex type between the Baxter-Belavin and the ACF elliptic R-matrices predicted previously by Avan and Rollet. It provides the higher order R-matrix identities and an explanation of the obtained equations through those for non-dynamical R-matrices. As a by-product we also get an interpretation of the intertwining transformation as matrix extension of scalar theta function likewise R-matrix is interpreted as matrix extension of the Kronecker function. Relations to the Gervais-Neveu-Felder equation and identities for the Felder’s elliptic R-matrix are also discussed.« less

Higher Matrix Stiffness Upregulates Osteopontin Expression in Hepatocellular Carcinoma Cells Mediated by Integrin β1/GSK3β/β-Catenin Signaling Pathway.

PubMed

You, Yang; Zheng, Qiongdan; Dong, Yinying; Wang, Yaohui; Zhang, Lan; Xue, Tongchun; Xie, Xiaoying; Hu, Chao; Wang, Zhiming; Chen, Rongxin; Wang, Yanhong; Cui, Jiefeng; Ren, Zhenggang

2015-01-01

Increased stromal stiffness is associated with hepatocellular carcinoma (HCC) development and progression. However, the molecular mechanism by which matrix stiffness stimuli modulate HCC progress is largely unknown. In this study, we explored whether matrix stiffness-mediated effects on osteopontin (OPN) expression occur in HCC cells. We used a previously reported in vitro culture system with tunable matrix stiffness and found that OPN expression was remarkably upregulated in HCC cells with increasing matrix stiffness. Furthermore, the phosphorylation level of GSK3β and the expression of nuclear β-catenin were also elevated, indicating that GSK3β/β-catenin pathway might be involved in OPN regulation. Knock-down analysis of integrin β1 showed that OPN expression and p-GSK3β level were downregulated in HCC cells grown on high stiffness substrate compared with controls. Simultaneously, inhibition of GSK-3β led to accumulation of β-catenin in the cytoplasm and its enhanced nuclear translocation, further triggered the rescue of OPN expression, suggesting that the integrin β1/GSK-3β/β-catenin pathway is specifically activated for matrix stiffness-mediated OPN upregulation in HCC cells. Tissue microarray analysis confirmed that OPN expression was positively correlated with the expression of LOX and COL1. Taken together, high matrix stiffness upregulated OPN expression in HCC cells via the integrin β1/GSK-3β/β-catenin signaling pathway. It highlights a new insight into a pathway involving physical mechanical signal and biochemical signal molecules which contributes to OPN expression in HCC cells.

Corrigendum: New Form of Kane's Equations of Motion for Constrained Systems

NASA Technical Reports Server (NTRS)

Roithmayr, Carlos M.; Bajodah, Abdulrahman H.; Hodges, Dewey H.; Chen, Ye-Hwa

2007-01-01

A correction to the previously published article "New Form of Kane's Equations of Motion for Constrained Systems" is presented. Misuse of the transformation matrix between time rates of change of the generalized coordinates and generalized speeds (sometimes called motion variables) resulted in a false conclusion concerning the symmetry of the generalized inertia matrix. The generalized inertia matrix (sometimes referred to as the mass matrix) is in fact symmetric and usually positive definite when one forms nonminimal Kane's equations for holonomic or simple nonholonomic systems, systems subject to nonlinear nonholonomic constraints, and holonomic or simple nonholonomic systems subject to impulsive constraints according to Refs. 1, 2, and 3, respectively. The mass matrix is of course symmetric when one forms minimal equations for holonomic or simple nonholonomic systems using Kane s method as set forth in Ref. 4.

Method of multivariate spectral analysis

DOEpatents

Keenan, Michael R.; Kotula, Paul G.

2004-01-06

A method of determining the properties of a sample from measured spectral data collected from the sample by performing a multivariate spectral analysis. The method can include: generating a two-dimensional matrix A containing measured spectral data; providing a weighted spectral data matrix D by performing a weighting operation on matrix A; factoring D into the product of two matrices, C and S.sup.T, by performing a constrained alternating least-squares analysis of D=CS.sup.T, where C is a concentration intensity matrix and S is a spectral shapes matrix; unweighting C and S by applying the inverse of the weighting used previously; and determining the properties of the sample by inspecting C and S. This method can be used to analyze X-ray spectral data generated by operating a Scanning Electron Microscope (SEM) with an attached Energy Dispersive Spectrometer (EDS).

Polymer-based metal nano-coated disposable target for matrix-assisted and matrix-free laser desorption/ionization mass spectrometry.

PubMed

Bugovsky, Stefan; Winkler, Wolfgang; Balika, Werner; Koranda, Manfred; Allmaier, Günter

2016-07-15

The ideal MALDI/LDI mass spectrometry sample target for an axial TOF instrument possesses a variety of properties. Primarily, it should be chemically inert to the sample, i.e. analyte, matrix and solvents, highly planar across the whole target, without any previous chemical contact and provide a uniform surface to facilitate reproducible measurements without artifacts from previous sample or matrix compounds. This can be hard to achieve with a metal target, which has to be extensively cleaned every time after use. Any cleaning step may leave residues behind, may change the surface properties due to the type of cleaning method used or even cause microscopic scratches over time hence altering matrix crystallization behavior. Alternatively, use of disposable targets avoids these problems. As each possesses the same surface they therefore have the potential to replace the conventional full metal targets so commonly employed. Furthermore, low cost single-use targets with high planarity promise an easier compliance with GLP guidelines as they alleviate the problem of low reproducibility due to inconsistent sample/matrix crystallization and changes to the target surface properties. In our tests, polymeric metal nano-coated targets were compared to a stainless steel reference. The polymeric metal nano-coated targets exhibited all the performance characteristics for a MALDI MS sample support, and even surpassed the - in our lab commonly used - reference in some aspects like limit of detection. The target exhibits all necessary features such as electrical conductivity, vacuum, laser and solvent compatibility. Copyright © 2016 Elsevier Inc. All rights reserved.

Visualizing cell extracellular matrix (ECM) deposited by cells cultured on aligned bacteriophage M13 thin films.

PubMed

Wu, Laying; Lee, L Andrew; Niu, Zhongwei; Ghoshroy, Soumitra; Wang, Qian

2011-08-02

Topographical features ranging from micro- to nanometers can affect cell orientation and migratory pathways, which are important factors in tissue engineering and tumor migration. In our previous study, a convective assembly of bacteriophage M13 resulted in thin films which could be used to control the alignment of cells. However, several questions regarding its underlying reasons to dictate cell alignment remained unanswered. Here, we further study the nanometer topographical features generated by the bacteriophage M13 crystalline film, which results in the alignment of the cells and extracellular matrix (ECM) proteins. Sequential imaging analyses at micro- and nanoscale levels of aligned cells and fibrillar matrix proteins were documented using scanning electron microscopy and immunofluorescence microscopy. As a result, we observed baby hamster kidney cells with higher degree of alignment on the ordered M13 substrates than NIH-3T3 fibroblasts, a difference which could be attributed to the intrinsic nature of the cells' production of ECM proteins. The results from this study provide a crucial insight into the topographical features of a biological thin film, which can be utilized to control the orientation of cells and surrounding ECM proteins.

Global quantum discord and matrix product density operators

NASA Astrophysics Data System (ADS)

Huang, Hai-Lin; Cheng, Hong-Guang; Guo, Xiao; Zhang, Duo; Wu, Yuyin; Xu, Jian; Sun, Zhao-Yu

2018-06-01

In a previous study, we have proposed a procedure to study global quantum discord in 1D chains whose ground states are described by matrix product states [Z.-Y. Sun et al., Ann. Phys. 359, 115 (2015)]. In this paper, we show that with a very simple generalization, the procedure can be used to investigate quantum mixed states described by matrix product density operators, such as quantum chains at finite temperatures and 1D subchains in high-dimensional lattices. As an example, we study the global discord in the ground state of a 2D transverse-field Ising lattice, and pay our attention to the scaling behavior of global discord in 1D sub-chains of the lattice. We find that, for any strength of the magnetic field, global discord always shows a linear scaling behavior as the increase of the length of the sub-chains. In addition, global discord and the so-called "discord density" can be used to indicate the quantum phase transition in the model. Furthermore, based upon our numerical results, we make some reliable predictions about the scaling of global discord defined on the n × n sub-squares in the lattice.

Students' proficiency scores within multitrait item response theory

NASA Astrophysics Data System (ADS)

Scott, Terry F.; Schumayer, Daniel

2015-12-01

In this paper we present a series of item response models of data collected using the Force Concept Inventory. The Force Concept Inventory (FCI) was designed to poll the Newtonian conception of force viewed as a multidimensional concept, that is, as a complex of distinguishable conceptual dimensions. Several previous studies have developed single-trait item response models of FCI data; however, we feel that multidimensional models are also appropriate given the explicitly multidimensional design of the inventory. The models employed in the research reported here vary in both the number of fitting parameters and the number of underlying latent traits assumed. We calculate several model information statistics to ensure adequate model fit and to determine which of the models provides the optimal balance of information and parsimony. Our analysis indicates that all item response models tested, from the single-trait Rasch model through to a model with ten latent traits, satisfy the standard requirements of fit. However, analysis of model information criteria indicates that the five-trait model is optimal. We note that an earlier factor analysis of the same FCI data also led to a five-factor model. Furthermore the factors in our previous study and the traits identified in the current work match each other well. The optimal five-trait model assigns proficiency scores to all respondents for each of the five traits. We construct a correlation matrix between the proficiencies in each of these traits. This correlation matrix shows strong correlations between some proficiencies, and strong anticorrelations between others. We present an interpretation of this correlation matrix.

Tamarixetin 3-O-β-d-Glucopyranoside from Azadirachta indica Leaves: Gastroprotective Role through Inhibition of Matrix Metalloproteinase-9 Activity in Mice.

PubMed

Yadav, Dharmendra K; Bharitkar, Yogesh P; Hazra, Abhijit; Pal, Uttam; Verma, Sugreev; Jana, Sayantan; Singh, Umesh P; Maiti, Nakul C; Mondal, Nirup B; Swarnakar, Snehasikta

2017-05-26

Neem (Azadirachta indica) is a well-known medicinal and insecticidal plant. Although previous studies have reported the antiulcer activity of neem leaf extract, the lead compound is still unidentified. The present study reports tamarixetin 3-O-β-d-glucopyranoside (1) from a methanol extract of neem leaves and its gastroprotective activity in an animal model. Compound 1 showed significant protection against indomethacin-induced gastric ulceration in mice in a dose-dependent manner. Moreover, ex vivo and circular dichroism studies confirmed that 1 inhibited the enzyme matrix metalloproteinase-9 (MMP-9) activity with an IC 50 value of ca. 50 μM. Molecular docking and dynamics showed the binding of 1 into the pocket of the active site of MMP-9, forming a coordination complex with the catalytic zinc, thus leading to inhibition of MMP-9 activity.

Stimulatory effects of advanced glycation endproducts (AGEs) on fibronectin matrix assembly.

PubMed

Pastino, Alexandra K; Greco, Todd M; Mathias, Rommel A; Cristea, Ileana M; Schwarzbauer, Jean E

2017-05-01

Advanced glycation endproducts (AGEs) are a heterogeneous group of compounds that form via non-enzymatic glycation of proteins throughout our lifespan and at a higher rate in certain chronic diseases such as diabetes. AGEs contribute to the progression of fibrosis, in part by stimulating cellular pathways that affect gene expression. Long-lived ECM proteins are targets for non-enzymatic glycation but the question of whether the AGE-modified ECM leads to excess ECM accumulation and fibrosis remains unanswered. In this study, cellular changes due to AGE accretion in the ECM were investigated. Non-enzymatic glycation of proteins in a decellularized fibroblast ECM was achieved by incubating the ECM in a solution of methylglyoxal (MGO). Mass spectrometry of fibronectin (FN) isolated from the glycated matrix identified twenty-eight previously unidentified MGO-derived AGE modification sites including functional sites such as the RGD integrin-binding sequence. Mesangial cells grown on the glycated, decellularized matrix assembled increased amounts of FN matrix. Soluble AGE-modified bovine serum albumin (BSA) also stimulated FN matrix assembly and this effect was reduced by function-blocking antibodies against the receptor for AGE (RAGE). These results indicate that cells respond to AGEs by increasing matrix assembly and that RAGE is involved in this response. This raises the possibility that the accumulation of ECM during the progression of fibrosis may be enhanced by cell interactions with AGEs on a glycated ECM. Copyright © 2016 Elsevier B.V. All rights reserved.

Using molecular dynamics simulations and finite element method to study the mechanical properties of nanotube reinforced polyethylene and polyketone

NASA Astrophysics Data System (ADS)

Rouhi, S.; Alizadeh, Y.; Ansari, R.; Aryayi, M.

2015-09-01

Molecular dynamics simulations are used to study the mechanical behavior of single-walled carbon nanotube reinforced composites. Polyethylene and polyketone are selected as the polymer matrices. The effects of nanotube atomic structure and diameter on the mechanical properties of polymer matrix nanocomposites are investigated. It is shown that although adding nanotube to the polymer matrix raises the longitudinal elastic modulus significantly, the transverse tensile and shear moduli do not experience important change. As the previous finite element models could not be used for polymer matrices with the atom types other than carbon, molecular dynamics simulations are used to propose a finite element model which can be used for any polymer matrices. It is shown that this model can predict Young’s modulus with an acceptable accuracy.

A differential CDM model for fatigue of unidirectional metal matrix composites

NASA Technical Reports Server (NTRS)

Arnold, S. M.; Kruch, S.

1992-01-01

A multiaxial, isothermal, continuum damage mechanics (CDM) model for fatigue of a unidirectional metal matrix composite volume element is presented. The model is phenomenological, stress based, and assumes a single scalar internal damage variable, the evolution of which is anisotropic. The development of the fatigue damage model, (i.e., evolutionary law) is based on the definition of an initially transversely isotropic fatigue limit surface, a static fracture surface, and a normalized stress amplitude function. The anisotropy of these surfaces and function, and therefore the model, is defined through physically meaningful invariants reflecting the local stress and material orientation. This transversely isotropic model is shown, when taken to it's isotropic limit, to directly simplify to a previously developed and validated isotropic fatigue continuum damage model. Results of a nondimensional parametric study illustrate (1) the flexibility of the present formulation in attempting to characterize a class of composite materials, and (2) the capability of the formulation in predicting anticipated qualitative trends in the fatigue behavior of unidirectional metal matrix composites. Also, specific material parameters representing an initial characterization of the composite system SiC/Ti 15-3 and the matrix material (Ti 15-3) are reported.

Proteolytic processing of lysyl oxidase-like-2 in the extracellular matrix is required for crosslinking of basement membrane collagen IV.

PubMed

López-Jiménez, Alberto J; Basak, Trayambak; Vanacore, Roberto M

2017-10-13

Lysyl oxidase-like-2 (LOXL2) is an enzyme secreted into the extracellular matrix that crosslinks collagens by mediating oxidative deamination of lysine residues. Our previous work demonstrated that this enzyme crosslinks the 7S domain, a structural domain that stabilizes collagen IV scaffolds in the basement membrane. Despite its relevant role in extracellular matrix biosynthesis, little is known about the structural requirements of LOXL2 that enable collagen IV crosslinking. In this study, we demonstrate that LOXL2 is processed extracellularly by serine proteases, generating a 65-kDa form lacking the first two scavenger receptor cysteine-rich domains. Site-specific mutagenesis to prevent proteolytic processing generated a full-length enzyme that is active in vitro toward a soluble substrate, but fails to crosslink insoluble collagen IV within the extracellular matrix. In contrast, the processed form of LOXL2 binds to collagen IV and crosslinks the 7S domain. Together, our data demonstrate that proteolytic processing is an important event that allows LOXL2-mediated crosslinking of basement membrane collagen IV. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Semicarbazide-sensitive amine oxidase and extracellular matrix deposition by smooth-muscle cells

NASA Technical Reports Server (NTRS)

Langford, Shannon D.; Trent, Margaret B.; Boor, Paul J.

2002-01-01

We have recently reported in vivo disruption of collagen and elastin architecture within blood vessel walls resulting from the selective inhibition of the enzyme semicarbazide-sensitive amine oxidase (SSAO). This study further investigates the effects of SSAO inhibition on extracellular matrix deposition by smooth-muscle cells (SMCs) cultured from neonatal rat hearts. SMCs were characterized, SSAO activity was measured, and soluble and insoluble collagen and elastin in the extracellular matrix (ECM) were quantified. Cultured neonatal rat heart SMC exhibited a monotypic synthetic phenotype that likely represents a myofibroblast. Detectable levels of SSAO activity present throughout 30-d culture peaked at 7-14 d, coinciding with the production of ECM. The addition of enzyme inhibitors and alternate SSAO substrates (benzylamine) produced varied and, in some cases, marked changes in SSAO activity as well as in the composition of mature and soluble matrix components. Similar to our previous in vivo findings, in vitro SSAO inhibition produced aberrations in collagen and elastin deposition by heart SMC. Because changes in SSAO activity are associated with cardiovascular pathologic states, this enzyme may play a protective or modulating role by regulating ECM production during pathologic insult.

Matrix Transformation in Boron Containing High-Temperature Co-Re-Cr Alloys

NASA Astrophysics Data System (ADS)

Strunz, Pavel; Mukherji, Debashis; Beran, Přemysl; Gilles, Ralph; Karge, Lukas; Hofmann, Michael; Hoelzel, Markus; Rösler, Joachim; Farkas, Gergely

2018-03-01

An addition of boron largely increases the ductility in polycrystalline high-temperature Co-Re alloys. Therefore, the effect of boron on the alloy structural characteristics is of high importance for the stability of the matrix at operational temperatures. Volume fractions of ɛ (hexagonal close-packed—hcp), γ (face-centered cubic—fcc) and σ (Cr2Re3 type) phases were measured at ambient and high temperatures (up to 1500 °C) for a boron-containing Co-17Re-23Cr alloy using neutron diffraction. The matrix phase undergoes an allotropic transformation from ɛ to γ structure at high temperatures, similar to pure cobalt and to the previously investigated, more complex Co-17Re-23Cr-1.2Ta-2.6C alloy. It was determined in this study that the transformation temperature depends on the boron content (0-1000 wt. ppm). Nevertheless, the transformation temperature did not change monotonically with the increase in the boron content but reached a minimum at approximately 200 ppm of boron. A probable reason is the interplay between the amount of boron in the matrix and the amount of σ phase, which binds hcp-stabilizing elements (Cr and Re). Moreover, borides were identified in alloys with high boron content.

In Vivo Validation of Volume Flow Measurements of Pulsatile Flow Using a Clinical Ultrasound System and Matrix Array Transducer.

PubMed

Hudson, John M; Williams, Ross; Milot, Laurent; Wei, Qifeng; Jago, James; Burns, Peter N

2017-03-01

The goal of this study was to evaluate the accuracy of a non-invasive C-plane Doppler estimation of pulsatile blood flow in the lower abdominal vessels of a porcine model. Doppler ultrasound measurements from a matrix array transducer system were compared with invasive volume flow measurements made on the same vessels with a surgically implanted ultrasonic transit-time flow probe. For volume flow rates ranging from 60 to 750 mL/min, agreement was very good, with a Pearson correlation coefficient of 0.97 (p < 0.0001) and a mean bias of -4.2%. The combination of 2-D matrix array technology and fast processing gives this Doppler method clinical potential, as many of the user- and system-dependent parameters of previous methods, including explicit vessel angle and diameter measurements, are eliminated. Copyright © 2016 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

Development of biomimetic nanocomposites as bone extracellular matrix for human osteoblastic cells.

PubMed

Bhowmick, Arundhati; Mitra, Tapas; Gnanamani, Arumugam; Das, Manas; Kundu, Patit Paban

2016-05-05

Here, we have developed biomimetic nanocomposites containing chitosan, poly(vinyl alcohol) and nano-hydroxyapatite-zinc oxide as bone extracellular matrix for human osteoblastic cells and characterized by Fourier transform infrared spectroscopy, powder X-ray diffraction. Scanning electron microscopy images revealed interconnected macroporous structures. Moreover, in this study, the problem related to fabricating a porous composite with good mechanical strength has been resolved by incorporating 5wt% of nano-hydroxyapatite-zinc oxide into chitosan-poly(vinyl alcohol) matrix; the present composite showed high tensile strength (20.25MPa) while maintaining appreciable porosity (65.25%). These values are similar to human cancellous bone. These nanocomposites also showed superior water uptake, antimicrobial and biodegradable properties than the previously reported results. Compatibility with human blood and pH was observed, indicating nontoxicity of these materials to the human body. Moreover, proliferation of osteoblastic MG-63 cells onto the nanocomposites was also observed without having any negative effect. Copyright © 2016 Elsevier Ltd. All rights reserved.

Intra-Articular Lubricin Gene Therapy for Post-Traumatic Arthritis

DTIC Science & Technology

2015-09-01

recreational activities. In our previously funded work, we developed the Yucatan minipig as a large animal model of PTOA following an intra-articular...65% in the deep zone. Water allows load-dependent deformation of the cartilage. It provides nutrition and medium for lubrication, creating a low...spread within the matrix. Chondrocytes receive their nutrition by diffusion through the matrix. Chondrocytes are specialized cells for synthesizing

Performance evaluation of matrix gradient coils.

PubMed

Jia, Feng; Schultz, Gerrit; Testud, Frederik; Welz, Anna Masako; Weber, Hans; Littin, Sebastian; Yu, Huijun; Hennig, Jürgen; Zaitsev, Maxim

2016-02-01

In this paper, we present a new performance measure of a matrix coil (also known as multi-coil) from the perspective of efficient, local, non-linear encoding without explicitly considering target encoding fields. An optimization problem based on a joint optimization for the non-linear encoding fields is formulated. Based on the derived objective function, a figure of merit of a matrix coil is defined, which is a generalization of a previously known resistive figure of merit for traditional gradient coils. A cylindrical matrix coil design with a high number of elements is used to illustrate the proposed performance measure. The results are analyzed to reveal novel features of matrix coil designs, which allowed us to optimize coil parameters, such as number of coil elements. A comparison to a scaled, existing multi-coil is also provided to demonstrate the use of the proposed performance parameter. The assessment of a matrix gradient coil profits from using a single performance parameter that takes the local encoding performance of the coil into account in relation to the dissipated power.

Matrix-free mass spectrometric imaging using laser desorption ionisation Fourier transform ion cyclotron resonance mass spectrometry.

PubMed

Goodwin, Richard J A; Pitt, Andrew R; Harrison, David; Weidt, Stefan K; Langridge-Smith, Pat R R; Barrett, Michael P; Logan Mackay, C

2011-04-15

Mass spectrometry imaging (MSI) is a powerful tool in metabolomics and proteomics for the spatial localization and identification of pharmaceuticals, metabolites, lipids, peptides and proteins in biological tissues. However, sample preparation remains a crucial variable in obtaining the most accurate distributions. Common washing steps used to remove salts, and solvent-based matrix application, allow analyte spreading to occur. Solvent-free matrix applications can reduce this risk, but increase the possibility of ionisation bias due to matrix adhesion to tissue sections. We report here the use of matrix-free MSI using laser desorption ionisation performed on a 12 T Fourier transform ion cyclotron resonance (FTICR) mass spectrometer. We used unprocessed tissue with no post-processing following thaw-mounting on matrix-assisted laser desorption ionisation (MALDI) indium-tin oxide (ITO) target plates. The identification and distribution of a range of phospholipids in mouse brain and kidney sections are presented and compared with previously published MALDI time-of-flight (TOF) MSI distributions. Copyright © 2011 John Wiley & Sons, Ltd.

Comprehensive Thematic T-Matrix Reference Database: A 2014-2015 Update

NASA Technical Reports Server (NTRS)

Mishchenko, Michael I.; Zakharova, Nadezhda; Khlebtsov, Nikolai G.; Videen, Gorden; Wriedt, Thomas

2015-01-01

The T-matrix method is one of the most versatile and efficient direct computer solvers of the macroscopic Maxwell equations and is widely used for the computation of electromagnetic scattering by single and composite particles, discrete random media, and particles in the vicinity of an interface separating two half-spaces with different refractive indices. This paper is the seventh update to the comprehensive thematic database of peer-reviewed T-matrix publications initiated by us in 2004 and includes relevant publications that have appeared since 2013. It also lists a number of earlier publications overlooked previously.

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

Albeverio, Sergio; Chen Kai; Fei Shaoming

A necessary separability criterion that relates the structures of the total density matrix and its reductions is given. The method used is based on the realignment method [K. Chen and L. A. Wu, Quant. Inf. Comput. 3, 193 (2003)]. The separability criterion naturally generalizes the reduction separability criterion introduced independently in the previous work [M. Horodecki and P. Horodecki, Phys. Rev. A 59, 4206 (1999) and N. J. Cerf, C. Adami, and R. M. Gingrich, Phys. Rev. A 60, 898 (1999)]. In special cases, it recovers the previous reduction criterion and the recent generalized partial transposition criterion [K. Chen andmore » L. A. Wu, Phys. Lett. A 306, 14 (2002)]. The criterion involves only simple matrix manipulations and can therefore be easily applied.« less

Preprocessing with image denoising and histogram equalization for endoscopy image analysis using texture analysis.

PubMed

Hiroyasu, Tomoyuki; Hayashinuma, Katsutoshi; Ichikawa, Hiroshi; Yagi, Nobuaki

2015-08-01

A preprocessing method for endoscopy image analysis using texture analysis is proposed. In a previous study, we proposed a feature value that combines a co-occurrence matrix and a run-length matrix to analyze the extent of early gastric cancer from images taken with narrow-band imaging endoscopy. However, the obtained feature value does not identify lesion zones correctly due to the influence of noise and halation. Therefore, we propose a new preprocessing method with a non-local means filter for de-noising and contrast limited adaptive histogram equalization. We have confirmed that the pattern of gastric mucosa in images can be improved by the proposed method. Furthermore, the lesion zone is shown more correctly by the obtained color map.

On optimal improvements of classical iterative schemes for Z-matrices

NASA Astrophysics Data System (ADS)

Noutsos, D.; Tzoumas, M.

2006-04-01

Many researchers have considered preconditioners, applied to linear systems, whose matrix coefficient is a Z- or an M-matrix, that make the associated Jacobi and Gauss-Seidel methods converge asymptotically faster than the unpreconditioned ones. Such preconditioners are chosen so that they eliminate the off-diagonal elements of the same column or the elements of the first upper diagonal [Milaszewicz, LAA 93 (1987) 161-170], Gunawardena et al. [LAA 154-156 (1991) 123-143]. In this work we generalize the previous preconditioners to obtain optimal methods. "Good" Jacobi and Gauss-Seidel algorithms are given and preconditioners, that eliminate more than one entry per row, are also proposed and analyzed. Moreover, the behavior of the above preconditioners to the Krylov subspace methods is studied.

Expanding (3+1)-dimensional universe from a lorentzian matrix model for superstring theory in (9+1) dimensions.

PubMed

Kim, Sang-Woo; Nishimura, Jun; Tsuchiya, Asato

2012-01-06

We reconsider the matrix model formulation of type IIB superstring theory in (9+1)-dimensional space-time. Unlike the previous works in which the Wick rotation was used to make the model well defined, we regularize the Lorentzian model by introducing infrared cutoffs in both the spatial and temporal directions. Monte Carlo studies reveal that the two cutoffs can be removed in the large-N limit and that the theory thus obtained has no parameters other than one scale parameter. Moreover, we find that three out of nine spatial directions start to expand at some "critical time," after which the space has SO(3) symmetry instead of SO(9).

Nicotine-induced retardation of chondrogenesis through down-regulation of IGF-1 signaling pathway to inhibit matrix synthesis of growth plate chondrocytes in fetal rats

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

Deng, Yu; Cao, Hong; Cu, Fenglong

Previous studies have confirmed that maternal tobacco smoking causes intrauterine growth retardation (IUGR) and skeletal growth retardation. Among a multitude of chemicals associated with cigarette smoking, nicotine is one of the leading candidates for causing low birth weights. However, the possible mechanism of delayed chondrogenesis by prenatal nicotine exposure remains unclear. We investigated the effects of nicotine on fetal growth plate chondrocytes in vivo and in vitro. Rats were given 2.0 mg/kg·d of nicotine subcutaneously from gestational days 11 to 20. Prenatal nicotine exposure increased the levels of fetal blood corticosterone and resulted in fetal skeletal growth retardation. Moreover, nicotinemore » exposure induced the inhibition of matrix synthesis and down-regulation of insulin-like growth factor 1 (IGF-1) signaling in fetal growth plates. The effects of nicotine on growth plates were studied in vitro by exposing fetal growth plate chondrocytes to 0, 1, 10, or 100 μM of nicotine for 10 days. Nicotine inhibited matrix synthesis and down-regulated IGF-1 signaling in chondrocytes in a concentration-dependent manner. These results suggest that prenatal nicotine exposure induces delayed chondrogenesis and that the mechanism may involve the down-regulation of IGF-1 signaling and the inhibition of matrix synthesis by growth plate chondrocytes. The present study aids in the characterization of delayed chondrogenesis caused by prenatal nicotine exposure, which might suggest a candidate mechanism for intrauterine origins of osteoporosis and osteoarthritis. - Highlights: ► Prenatal nicotine-exposure could induce delayed chondrogenesis in fetal rats. ► Nicotine inhibits matrix synthesis of fetal growth plate chondrocytes. ► Nicotine inhibits IGF-1 signaling pathway in fetal growth plate chondrocytes.« less

Selective Cell Adhesion and Biosensing Applications of Bio-Active Block Copolymers Prepared by CuAAC/Thiol-ene Double Click Reactions.

PubMed

Oyman Eyrilmez, Gizem; Doran, Sean; Murtezi, Eljesa; Demir, Bilal; Odaci Demirkol, Dilek; Coskunol, Hakan; Timur, Suna; Yagci, Yusuf

2015-09-01

N-Acetyl-l-cysteine (NAC)-capped poly(methyl methacrylate)-b-polycaprolactone block copolymer (PMMA-b-PCL-NAC) was prepared using the previously described one-pot photoinduced sequential CuAAC/thiol-ene double click procedure. PMMA-b-PCL-NAC had previously shown good applicability as a matrix for cell adhesion of cells from the Vero cell line (African green monkey kidney epithelial). Here, in this work, PMMA-b-PCL-NAC served as an excellent immobilization matrix for biomolecule conjugation. Covalent binding of RGD (R: arginine, G: glycine, and D: aspartic acid) peptide sequence onto the PMMA-b-PCL-NAC-coated surface was performed via EDC chemistry. RGD-modified PMMA-b-PCL-NAC (PMMA-b-PCL-NAC-RGD) as a non-toxic cell proliferation platform was used for selective "integrin αvβ3-mediated cell adhesion and biosensing studies. Both optical and electrochemical techniques were used to monitor the adhesion differences between "integrin αvβ3" receptor positive and negative cell lines on to the designed biofunctional surfaces. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Study of dipion transitions among Υ(3S), Υ(2S), and Υ(1S) states

NASA Astrophysics Data System (ADS)

Cronin-Hennessy, D.; Gao, K. Y.; Hietala, J.; Kubota, Y.; Klein, T.; Lang, B. W.; Poling, R.; Scott, A. W.; Smith, A.; Zweber, P.; Dobbs, S.; Metreveli, Z.; Seth, K. K.; Tomaradze, A.; Ernst, J.; Ecklund, K. M.; Severini, H.; Love, W.; Savinov, V.; Lopez, A.; Mehrabyan, S.; Mendez, H.; Ramirez, J.; Huang, G. S.; Miller, D. H.; Pavlunin, V.; Sanghi, B.; Shipsey, I. P. J.; Xin, B.; Adams, G. S.; Anderson, M.; Cummings, J. P.; Danko, I.; Hu, D.; Moziak, B.; Napolitano, J.; He, Q.; Insler, J.; Muramatsu, H.; Park, C. S.; Thorndike, E. H.; Yang, F.; Artuso, M.; Blusk, S.; Khalil, S.; Li, J.; Menaa, N.; Mountain, R.; Nisar, S.; Randrianarivony, K.; Sia, R.; Skwarnicki, T.; Stone, S.; Wang, J. C.; Bonvicini, G.; Cinabro, D.; Dubrovin, M.; Lincoln, A.; Pappas, S. P.; Weinstein, A. J.; Asner, D. M.; Edwards, K. W.; Naik, P.; Briere, R. A.; Ferguson, T.; Tatishvili, G.; Vogel, H.; Watkins, M. E.; Rosner, J. L.; Adam, N. E.; Alexander, J. P.; Cassel, D. G.; Duboscq, J. E.; Ehrlich, R.; Fields, L.; Galik, R. S.; Gibbons, L.; Gray, R.; Gray, S. W.; Hartill, D. L.; Heltsley, B. K.; Hertz, D.; Jones, C. D.; Kandaswamy, J.; Kreinick, D. L.; Kuznetsov, V. E.; Mahlke-Krüger, H.; Mohapatra, D.; Onyisi, P. U. E.; Patterson, J. R.; Peterson, D.; Pivarski, J.; Riley, D.; Ryd, A.; Sadoff, A. J.; Schwarthoff, H.; Shi, X.; Stroiney, S.; Sun, W. M.; Wilksen, T.; Athar, S. B.; Patel, R.; Yelton, J.; Rubin, P.; Cawlfield, C.; Eisenstein, B. I.; Karliner, I.; Kim, D.; Lowrey, N.; Selen, M.; White, E. J.; Wiss, J.; Mitchell, R. E.; Shepherd, M. R.; Besson, D.; Pedlar, T. K.

2007-10-01

We present measurements of decay matrix elements for hadronic transitions of the form Υ(nS)→Υ(mS)ππ, where (n,m)=(3,1),(2,1),(3,2). We reconstruct charged and neutral pion modes with the final state Upsilon decaying to either μ+μ- or e+e-. Dalitz plot distributions for the 12 decay modes are fit individually as well as jointly assuming isospin symmetry, thereby measuring the matrix elements of the decay amplitude. We observe and account for the anomaly previously noted in the dipion invariant mass distribution for the Υ(3S)→Υ(1S)ππ transition and obtain good descriptions of the dynamics of the decay using the most general decay amplitude allowed by partial conservation of the axial-vector current considerations. The fits further indicate that the Υ(2S)→Υ(1S)ππ and Υ(3S)→Υ(2S)ππ transitions also show the presence of terms in the decay amplitude that were previously ignored, although at a relatively suppressed level.

Critical assessment of the formation of hydrogen peroxide in dough by fermenting yeast cells.

PubMed

Rezaei, Mohammad N; Dornez, Emmie; Verstrepen, Kevin J; Courtin, Christophe M

2015-02-01

Fermentation of bread dough leads to strengthening of the dough matrix. This effect has previously been ascribed to the action of hydrogen peroxide (H2O2) produced by yeast in dough. In this study, we re-evaluate the production of H2O2 by yeast in dough and aqueous fermentation broth. Results show that the previously reported high levels of H2O2 in fermenting dough were most probably due to the lack of specificity of the potassium dichromate/acetic acid-based method used. Using the chemiluminescent HyPerBlu assay, no yeast H2O2 production could be detected in fermented dough or broth. Even though the formation of low levels of H2O2 cannot be ruled out due to the presence of catalase in flour and the fast reaction of H2O2 with gluten proteins, our results suggest that the changes in dough matrix rheological properties upon fermentation are not due to production of H2O2 by yeast. Copyright © 2014 Elsevier Ltd. All rights reserved.

Enamel proteins mitigate mechanical and structural degradations in mature human enamel during acid attack

NASA Astrophysics Data System (ADS)

Lubarsky, Gennady V.; Lemoine, Patrick; Meenan, Brian J.; Deb, Sanjukta; Mutreja, Isha; Carolan, Patrick; Petkov, Nikolay

2014-04-01

A hydrazine deproteination process was used to investigate the role of enamel proteins in the acid erosion of mature human dental enamel. Bright field high resolution transmission electron micrographs and x-ray diffraction analysis show no crystallographic changes after the hydrazine treatment with similar nanoscale hydroxyapatite crystallite size and orientation for sound and de-proteinated enamel. However, the presence of enamel proteins reduces the erosion depth, the loss of hardness and the loss of structural order in enamel, following exposure to citric acid. Nanoindentation creep is larger for sound enamel than for deproteinated enamel but it reduces in sound enamel after acid attack. These novel results are consistent with calcium ion-mediated visco-elasticty in enamel matrix proteins as described previously for nacre, bone and dental proteins. They are also in good agreement with a previous double layer force spectroscopy study by the authors which found that the proteins electrochemically buffer enamel against acid attack. Finally, this suggests that acid attack, and more specifically dental erosion, is influenced by ionic permeation through the enamel layer and that it is mitigated by the enamel protein matrix.

Synthesis and morphology of hydroxyapatite/polyethylene oxide nanocomposites with block copolymer compatibilized interfaces

NASA Astrophysics Data System (ADS)

Lee, Ji Hoon; Shofner, Meisha

2012-02-01

In order to exploit the promise of polymer nanocomposites, special consideration should be given to component interfaces during synthesis and processing. Previous results from this group have shown that nanoparticles clustered into larger structures consistent with their native shape when the polymer matrix crystallinity was high. Therefore in this research, the nanoparticles are disguised from a highly-crystalline polymer matrix by cloaking them with a matrix-compatible block copolymer. Specifically, spherical and needle-shaped hydroxyapatite nanoparticles were synthesized using a block copolymer templating method. The block copolymer used, polyethylene oxide-b-polymethacrylic acid, remained on the nanoparticle surface following synthesis with the polyethylene oxide block exposed. These nanoparticles were subsequently added to a polyethylene oxide matrix using solution processing. Characterization of the nanocomposites indicated that the copolymer coating prevented the nanoparticles from assembling into ordered clusters and that the matrix crystallinity was decreased at a nanoparticle spacing of approximately 100 nm.

Apparatus and system for multivariate spectral analysis

DOEpatents

Keenan, Michael R.; Kotula, Paul G.

2003-06-24

An apparatus and system for determining the properties of a sample from measured spectral data collected from the sample by performing a method of multivariate spectral analysis. The method can include: generating a two-dimensional matrix A containing measured spectral data; providing a weighted spectral data matrix D by performing a weighting operation on matrix A; factoring D into the product of two matrices, C and S.sup.T, by performing a constrained alternating least-squares analysis of D=CS.sup.T, where C is a concentration intensity matrix and S is a spectral shapes matrix; unweighting C and S by applying the inverse of the weighting used previously; and determining the properties of the sample by inspecting C and S. This method can be used by a spectrum analyzer to process X-ray spectral data generated by a spectral analysis system that can include a Scanning Electron Microscope (SEM) with an Energy Dispersive Detector and Pulse Height Analyzer.

Geographic extension of an uneven-aged, multi-species matrix growth model for northern hardwood forests

Treesearch

Audra E. Kolbe; Joseph Buongiorno; Michael Vasievich

1999-01-01

The objective of this study was to update and extend the geographic range of a forest growth model for northern hardwoods, developed previously with data from the fourth Wisconsin inventory (Lin et al., 1996. Ecol. Model., 91: 193-211.). To this end, Lin's model was recalibrated with data from the recent fifth inventory of Wisconsin and Michigan, and with the...

Interactions between human osteoblasts and prostate cancer cells in a novel 3D in vitro model

PubMed Central

Sieh, Shirly; Lubik, Amy A; Clements, Judith A; Nelson, Colleen C

2010-01-01

Cell-cell and cell-matrix interactions play a major role in tumor morphogenesis and cancer metastasis. Therefore, it is crucial to create a model with a biomimetic microenvironment that allows such interactions to fully represent the pathophysiology of a disease for an in vitro study. This is achievable by using three-dimensional (3D) models instead of conventional two-dimensional (2D) cultures with the aid of tissue engineering technology. We are now able to better address the complex intercellular interactions underlying prostate cancer (CaP) bone metastasis through such models. In this study, we assessed the interaction of CaP cells and human osteoblasts (hOBs) within a tissue engineered bone (TEB) construct. Consistent with other in vivo studies, our findings show that intercellular and CaP cell-bone matrix interactions lead to elevated levels of matrix metalloproteinases, steroidogenic enzymes and the CaP biomarker, prostate specific antigen (PSA); all associated with CaP metastasis. Hence, it highlights the physiological relevance of this model. We believe that this model will provide new insights for understanding of the previously poorly understood molecular mechanisms of bone metastasis, which will foster further translational studies, and ultimately offer a potential tool for drug screening. PMID:21197221

The Role of Viscoelasticity on the Fatigue of Angle-ply Polymer Matrix Composites at High and Room Temperatures- A Micromechanical Approach

NASA Astrophysics Data System (ADS)

Sayyidmousavi, Alireza; Bougherara, Habiba; Fawaz, Zouheir

2015-06-01

A micromechanical approach is adopted to study the role of viscoelasticity on the fatigue behavior of polymer matrix composites. In particular, the study examines the interaction of fatigue and creep in angle ply carbon/epoxy at 25 and 114 °C. The matrix phase is modeled as a vicoelastic material using Schapery's single integral constitutive equation. Taking viscoelsticity into account allows the study of creep strain evolution during the fatigue loading. The fatigue failure criterion is expressed in terms of the fatigue failure functions of the constituent materials. The micromechanical model is also used to calculate these fatigue failure functions from the knowledge of the S-N diagrams of the composite material in longitudinal, transverse and shear loadings thus eliminating the need for any further experimentation. Unlike the previous works, the present study can distinguish between the strain evolution due to fatigue and creep. The results can clearly show the contribution made by the effect of viscoelasticity to the total strain evolution during the fatigue life of the specimen. Although the effect of viscoelsticity is found to increase with temperature, its contribution to strain development during fatigue is compromised by the shorter life of the specimen when compared to lower temperatures.

The association between MMP2 -1306 C > T (rs243865) polymorphism and risk of prostate cancer.

PubMed

Shajarehpoor Salavati, L; Tafvizi, F; Manjili, H K

2017-02-01

Prostate cancer is the second most common cancer in men. Matrix metalloproteinase-2 (MMP2) is the most important member of the matrix metalloproteinase family. MMP2 digests the basement membrane and causes changes in the extracellular matrix which in turn facilitate cancer invasion. It, therefore, has a major role in tumor angiogenesis. Previous studies have identified a single-nucleotide polymorphism C/T at position -1306 of MMP2 gene promoter which is a key regulatory factor in cancer progression. The present study aimed to determine the association between MMP2 polymorphism and the risk of prostate cancer in Iranian men. This case-control study was performed on 50 paraffin-embedded prostate cancer tissue samples and 54 blood samples from healthy men. Genotyping of the samples was performed using high-resolution melting analysis (HRM). Finally, 20 % of the genotypes were confirmed by sequencing. No significant associations were found between CT and TT genotypes and the risk of prostate cancer. However, there were no significant relationships between the genotypes and the studied factors, e.g., age, pathological stage, and Gleason Score. MMP2 -1306 C > T (rs243865) polymorphism was not significantly related with prostate cancer susceptibility in Iranian men.

Comparative expression of the four enamel matrix protein genes, amelogenin, ameloblastin, enamelin and amelotin during amelogenesis in the lizard Anolis carolinensis.

PubMed

Gasse, Barbara; Sire, Jean-Yves

2015-01-01

In a recent study, we have demonstrated that amelotin (AMTN) gene structure and its expression during amelogenesis have changed during tetrapod evolution. Indeed, this gene is expressed throughout enamel matrix deposition and maturation in non-mammalian tetrapods, while in mammals its expression is restricted to the transition and maturation stages of amelogenesis. Previous studies of amelogenin (AMEL) gene expression in a lizard and a salamander have shown similar expression pattern to that in mammals, but to our knowledge there are no data regarding ameloblastin (AMBN) and enamelin (ENAM) expression in non-mammalian tetrapods. The present study aims to look at, and compare, the structure and expression of four enamel matrix protein genes, AMEL, AMBN, ENAM and AMTN during amelogenesis in the lizard Anolis carolinensis. We provide the full-length cDNA sequence of A. carolinensis AMEL and AMBN, and show for the first time the expression of ENAM and AMBN in a non-mammalian species. During amelogenesis in A. carolinensis, AMEL, AMBN and ENAM expression in ameloblasts is similar to that described in mammals. It is noteworthy that AMEL and AMBN expression is also found in odontoblasts. Our findings indicate that AMTN is the only enamel matrix protein gene that is differentially expressed in ameloblasts between mammals and sauropsids. Changes in AMTN structure and expression could be the key to explain the structural differences between mammalian and reptilian enamel, i.e. prismatic versus non-prismatic.

Activation of Parathyroid Hormone 2 Receptor Induces Decorin Expression and Promotes Wound Repair

PubMed Central

Sato, Emi; Zhang, Ling-juan; Dorschner, Robert A.; Adase, Christopher A.; Choudhury, Biswa P.; Gallo, Richard L.

2018-01-01

In this study, we report that TIP39, a parathyroid hormone ligand family member that was recently identified to be expressed in the skin, can induce decorin expression and enhance wound repair. Topical treatment of mice with TIP39 accelerated wound repair, whereas TIP39-deficient mice had delayed repair that was associated with formation of abnormal collagen bundles. To study the potential mechanism responsible for the action of TIP39 in the dermis, fibroblasts were cultured in three-dimensional collagen gels, a process that results in enhanced decorin expression unless activated to differentiate to adipocytes, whereupon these cells reduce expression of several proteoglycans, including decorin. Small interfering RNA-mediated silencing of parathyroid hormone 2 receptor (PTH2R), the receptor for TIP39, suppressed the expression of extracellular matrix-related genes, including decorin, collagens, fibronectin, and matrix metalloproteases. Skin wounds in TIP39−/− mice had decreased decorin expression, and addition of TIP39 to cultured fibroblasts induced decorin and increased phosphorylation and nuclear translocation of CREB. Fibroblasts differentiated to adipocytes and treated with TIP39 also showed increased decorin and production of chondroitin sulfate. Furthermore, the skin of PTH2R−/− mice showed abnormal extracellular matrix structure, decreased decorin expression, and skin hardness. Thus, the TIP39-PTH2R system appears to be a previously unrecognized mechanism for regulation of extracellular matrix formation and wound repair. PMID:28454729

Volumetric characterization of human patellar cartilage matrix on phase contrast x-ray computed tomography

NASA Astrophysics Data System (ADS)

Abidin, Anas Z.; Nagarajan, Mahesh B.; Checefsky, Walter A.; Coan, Paola; Diemoz, Paul C.; Hobbs, Susan K.; Huber, Markus B.; Wismüller, Axel

2015-03-01

Phase contrast X-ray computed tomography (PCI-CT) has recently emerged as a novel imaging technique that allows visualization of cartilage soft tissue, subsequent examination of chondrocyte patterns, and their correlation to osteoarthritis. Previous studies have shown that 2D texture features are effective at distinguishing between healthy and osteoarthritic regions of interest annotated in the radial zone of cartilage matrix on PCI-CT images. In this study, we further extend the texture analysis to 3D and investigate the ability of volumetric texture features at characterizing chondrocyte patterns in the cartilage matrix for purposes of classification. Here, we extracted volumetric texture features derived from Minkowski Functionals and gray-level co-occurrence matrices (GLCM) from 496 volumes of interest (VOI) annotated on PCI-CT images of human patellar cartilage specimens. The extracted features were then used in a machine-learning task involving support vector regression to classify ROIs as healthy or osteoarthritic. Classification performance was evaluated using the area under the receiver operating characteristic (ROC) curve (AUC). The best classification performance was observed with GLCM features correlation (AUC = 0.83 +/- 0.06) and homogeneity (AUC = 0.82 +/- 0.07), which significantly outperformed all Minkowski Functionals (p < 0.05). These results suggest that such quantitative analysis of chondrocyte patterns in human patellar cartilage matrix involving GLCM-derived statistical features can distinguish between healthy and osteoarthritic tissue with high accuracy.

Fiber Development and Matrix Production in Tissue Engineered Menisci using Bovine Mesenchymal Stem Cells and Fibrochondrocytes

PubMed Central

McCorry, Mary Clare; Bonassar, Lawrence J.

2017-01-01

Mesenchymal stem cells (MSCs) have been investigated with promising results for meniscus healing and tissue engineering. While MSCs are known to contribute to ECM production, less is known about how MSCs produce and align large organized fibers for application to tissue engineering the meniscus. The goal of this study was to investigate the capability of MSCs to produce and organize extracellular matrix molecules compared to meniscal fibrochondrocytes (FCCs). Bovine FCCs and MSCs were encapsulated in an anatomically accurate collagen meniscus using mono-culture and co-culture of each cell type. Each meniscus was mechanically anchored at the horns to mimic the physiological fixation by the meniscal entheses. Mechanical fixation generates a static mechanical boundary condition previously shown to induce formation of oriented fiber by FCCs. Samples were cultured for 4 weeks and then evaluated for biochemical composition and fiber development. MSCs increased the GAG and collagen production in both co-culture and mono-culture groups compared to FCC mono-culture. Collagen organization was greatest in the FCC mono-culture group. While MSCs had increased matrix production they lacked the fiber organization capabilities of FCCs. This study suggests that GAG production and fiber formation are linked. Co-culture can be used as a means of balancing the synthetic properties of MSCs and the matrix remodeling capabilities of FCCs for tissue engineering applications. PMID:27925474

Limit analysis of hollow spheres or spheroids with Hill orthotropic matrix

NASA Astrophysics Data System (ADS)

Pastor, Franck; Pastor, Joseph; Kondo, Djimedo

2012-03-01

Recent theoretical studies of the literature are concerned by the hollow sphere or spheroid (confocal) problems with orthotropic Hill type matrix. They have been developed in the framework of the limit analysis kinematical approach by using very simple trial velocity fields. The present Note provides, through numerical upper and lower bounds, a rigorous assessment of the approximate criteria derived in these theoretical works. To this end, existing static 3D codes for a von Mises matrix have been easily extended to the orthotropic case. Conversely, instead of the non-obvious extension of the existing kinematic codes, a new original mixed approach has been elaborated on the basis of the plane strain structure formulation earlier developed by F. Pastor (2007). Indeed, such a formulation does not need the expressions of the unit dissipated powers. Interestingly, it delivers a numerical code better conditioned and notably more rapid than the previous one, while preserving the rigorous upper bound character of the corresponding numerical results. The efficiency of the whole approach is first demonstrated through comparisons of the results to the analytical upper bounds of Benzerga and Besson (2001) or Monchiet et al. (2008) in the case of spherical voids in the Hill matrix. Moreover, we provide upper and lower bounds results for the hollow spheroid with the Hill matrix which are compared to those of Monchiet et al. (2008).

High-Throughput Screening of Vascular Endothelium-Destructive or Protective Microenvironments: Cooperative Actions of Extracellular Matrix Composition, Stiffness, and Structure.

PubMed

Ding, Yonghui; Floren, Michael; Tan, Wei

2017-06-01

Pathological modification of the subendothelial extracellular matrix (ECM) has closely been associated with endothelial activation and subsequent cardiovascular disease progression. To understand regulatory mechanisms of these matrix modifications, the majority of previous efforts have focused on the modulation of either chemical composition or matrix stiffness on 2D smooth surfaces without simultaneously probing their cooperative effects on endothelium function on in vivo like 3D fibrous matrices. To this end, a high-throughput, combinatorial microarray platform on 2D and 3D hydrogel settings to resemble the compositions, stiffness, and structure of healthy and diseased subendothelial ECM has been established, and further their respective and combined effects on endothelial attachment, proliferation, inflammation, and junctional integrity have been investigated. For the first time, the results demonstrate that 3D fibrous structure resembling native ECM is a critical endothelium-protective microenvironmental factor by maintaining the stable, quiescent endothelium with strong resistance to proinflammatory stimuli. It is also revealed that matrix stiffening, in concert with chemical compositions resembling diseased ECM, particularly collagen III, could aggravate activation of nuclear factor kappa B, disruption of endothelium integrity, and susceptibility to proinflammatory stimuli. This study elucidates cooperative effects of various microenvironmental factors on endothelial activation and sheds light on new in vitro model for cardiovascular diseases. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Toughening mechanisms in bioinspired multilayered materials.

PubMed

Askarinejad, Sina; Rahbar, Nima

2015-01-06

Outstanding mechanical properties of biological multilayered materials are strongly influenced by nanoscale features in their structure. In this study, mechanical behaviour and toughening mechanisms of abalone nacre-inspired multilayered materials are explored. In nacre's structure, the organic matrix, pillars and the roughness of the aragonite platelets play important roles in its overall mechanical performance. A micromechanical model for multilayered biological materials is proposed to simulate their mechanical deformation and toughening mechanisms. The fundamental hypothesis of the model is the inclusion of nanoscale pillars with near theoretical strength (σth ~ E/30). It is also assumed that pillars and asperities confine the organic matrix to the proximity of the platelets, and, hence, increase their stiffness, since it has been previously shown that the organic matrix behaves more stiffly in the proximity of mineral platelets. The modelling results are in excellent agreement with the available experimental data for abalone nacre. The results demonstrate that the aragonite platelets, pillars and organic matrix synergistically affect the stiffness of nacre, and the pillars significantly contribute to the mechanical performance of nacre. It is also shown that the roughness induced interactions between the organic matrix and aragonite platelet, represented in the model by asperity elements, play a key role in strength and toughness of abalone nacre. The highly nonlinear behaviour of the proposed multilayered material is the result of distributed deformation in the nacre-like structure due to the existence of nano-asperities and nanopillars with near theoretical strength. Finally, tensile toughness is studied as a function of the components in the microstructure of nacre.

Toughening mechanisms in bioinspired multilayered materials

PubMed Central

Askarinejad, Sina; Rahbar, Nima

2015-01-01

Outstanding mechanical properties of biological multilayered materials are strongly influenced by nanoscale features in their structure. In this study, mechanical behaviour and toughening mechanisms of abalone nacre-inspired multilayered materials are explored. In nacre's structure, the organic matrix, pillars and the roughness of the aragonite platelets play important roles in its overall mechanical performance. A micromechanical model for multilayered biological materials is proposed to simulate their mechanical deformation and toughening mechanisms. The fundamental hypothesis of the model is the inclusion of nanoscale pillars with near theoretical strength (σth ~ E/30). It is also assumed that pillars and asperities confine the organic matrix to the proximity of the platelets, and, hence, increase their stiffness, since it has been previously shown that the organic matrix behaves more stiffly in the proximity of mineral platelets. The modelling results are in excellent agreement with the available experimental data for abalone nacre. The results demonstrate that the aragonite platelets, pillars and organic matrix synergistically affect the stiffness of nacre, and the pillars significantly contribute to the mechanical performance of nacre. It is also shown that the roughness induced interactions between the organic matrix and aragonite platelet, represented in the model by asperity elements, play a key role in strength and toughness of abalone nacre. The highly nonlinear behaviour of the proposed multilayered material is the result of distributed deformation in the nacre-like structure due to the existence of nano-asperities and nanopillars with near theoretical strength. Finally, tensile toughness is studied as a function of the components in the microstructure of nacre. PMID:25551150

Quantifying lost information due to covariance matrix estimation in parameter inference

NASA Astrophysics Data System (ADS)

Sellentin, Elena; Heavens, Alan F.

2017-02-01

Parameter inference with an estimated covariance matrix systematically loses information due to the remaining uncertainty of the covariance matrix. Here, we quantify this loss of precision and develop a framework to hypothetically restore it, which allows to judge how far away a given analysis is from the ideal case of a known covariance matrix. We point out that it is insufficient to estimate this loss by debiasing the Fisher matrix as previously done, due to a fundamental inequality that describes how biases arise in non-linear functions. We therefore develop direct estimators for parameter credibility contours and the figure of merit, finding that significantly fewer simulations than previously thought are sufficient to reach satisfactory precisions. We apply our results to DES Science Verification weak lensing data, detecting a 10 per cent loss of information that increases their credibility contours. No significant loss of information is found for KiDS. For a Euclid-like survey, with about 10 nuisance parameters we find that 2900 simulations are sufficient to limit the systematically lost information to 1 per cent, with an additional uncertainty of about 2 per cent. Without any nuisance parameters, 1900 simulations are sufficient to only lose 1 per cent of information. We further derive estimators for all quantities needed for forecasting with estimated covariance matrices. Our formalism allows to determine the sweetspot between running sophisticated simulations to reduce the number of nuisance parameters, and running as many fast simulations as possible.

A microwave backscattering model for precipitation

NASA Astrophysics Data System (ADS)

Ermis, Seda

A geophysical microwave backscattering model for space borne and ground-based remote sensing of precipitation is developed and used to analyze backscattering measurements from rain and snow type precipitation. Vector Radiative Transfer (VRT) equations for a multilayered inhomogeneous medium are applied to the precipitation region for calculation of backscattered intensity. Numerical solution of the VRT equation for multiple layers is provided by the matrix doubling method to take into account close range interactions between particles. In previous studies, the VRT model was used to calculate backscattering from a rain column on a sea surface. In the model, Mie scattering theory for closely spaced scatterers was used to determine the phase matrix for each sublayer characterized by a set of parameters. The scatterers i.e. rain drops within the sublayers were modelled as spheres with complex permittivities. The rain layer was bounded by rough boundaries; the interface between the cloud and the rain column as well as the interface between the sea surface and the rain were all analyzed by using the integral equation model (IEM). Therefore, the phase matrix for the entire rain column was generated by the combination of surface and volume scattering. Besides Mie scattering, in this study, we use T-matrix approach to examine the effect of the shape to the backscattered intensities since larger raindrops are most likely oblique in shape. Analyses show that the effect of obliquity of raindrops to the backscattered wave is related with size of the scatterers and operated frequency. For the ground-based measurement system, the VRT model is applied to simulate the precipitation column on horizontal direction. Therefore, the backscattered reflectivities for each unit range of volume are calculated from the backscattering radar cross sections by considering radar range and effective illuminated area of the radar beam. The volume scattering phase matrices for each range interval are calculated by Mie scattering theory. VRT equations are solved by matrix doubling method to compute phase matrix for entire radar beam. Model results are validated with measured data by X-band dual polarization Phase Tilt Weather Radar (PTWR) for snow, rain, wet hail type precipitation. The geophysical parameters given the best fit with measured reflectivities are used in previous models i.e. Rayleigh Approximation and Mie scattering and compared with the VRT model. Results show that reflectivities calculated by VRT models are differed up to 10 dB from the Rayleigh approximation model and up to 5 dB from the Mie Scattering theory due to both multiple scattering and attenuation losses for the rain rates as high as 80 mm/h.

On the multivariate total least-squares approach to empirical coordinate transformations. Three algorithms

NASA Astrophysics Data System (ADS)

Schaffrin, Burkhard; Felus, Yaron A.

2008-06-01

The multivariate total least-squares (MTLS) approach aims at estimating a matrix of parameters, Ξ, from a linear model ( Y- E Y = ( X- E X ) · Ξ) that includes an observation matrix, Y, another observation matrix, X, and matrices of randomly distributed errors, E Y and E X . Two special cases of the MTLS approach include the standard multivariate least-squares approach where only the observation matrix, Y, is perturbed by random errors and, on the other hand, the data least-squares approach where only the coefficient matrix X is affected by random errors. In a previous contribution, the authors derived an iterative algorithm to solve the MTLS problem by using the nonlinear Euler-Lagrange conditions. In this contribution, new lemmas are developed to analyze the iterative algorithm, modify it, and compare it with a new ‘closed form’ solution that is based on the singular-value decomposition. For an application, the total least-squares approach is used to estimate the affine transformation parameters that convert cadastral data from the old to the new Israeli datum. Technical aspects of this approach, such as scaling the data and fixing the columns in the coefficient matrix are investigated. This case study illuminates the issue of “symmetry” in the treatment of two sets of coordinates for identical point fields, a topic that had already been emphasized by Teunissen (1989, Festschrift to Torben Krarup, Geodetic Institute Bull no. 58, Copenhagen, Denmark, pp 335-342). The differences between the standard least-squares and the TLS approach are analyzed in terms of the estimated variance component and a first-order approximation of the dispersion matrix of the estimated parameters.

Bioengineering Human Myocardium on Native Extracellular Matrix

PubMed Central

Guyette, Jacques P.; Charest, Jonathan M; Mills, Robert W; Jank, Bernhard J.; Moser, Philipp T.; Gilpin, Sarah E.; Gershlak, Joshua R.; Okamoto, Tatsuya; Gonzalez, Gabriel; Milan, David J.; Gaudette, Glenn R.; Ott, Harald C.

2015-01-01

Rationale More than 25 million individuals suffer from heart failure worldwide, with nearly 4,000 patients currently awaiting heart transplantation in the United States. Donor organ shortage and allograft rejection remain major limitations with only about 2,500 hearts transplanted each year. As a theoretical alternative to allotransplantation, patient-derived bioartificial myocardium could provide functional support and ultimately impact the treatment of heart failure. Objective The objective of this study is to translate previous work to human scale and clinically relevant cells, for the bioengineering of functional myocardial tissue based on the combination of human cardiac matrix and human iPS-derived cardiac myocytes. Methods and Results To provide a clinically relevant tissue scaffold, we translated perfusion-decellularization to human scale and obtained biocompatible human acellular cardiac scaffolds with preserved extracellular matrix composition, architecture, and perfusable coronary vasculature. We then repopulated this native human cardiac matrix with cardiac myocytes derived from non-transgenic human induced pluripotent stem cells (iPSCs) and generated tissues of increasing three-dimensional complexity. We maintained such cardiac tissue constructs in culture for 120 days to demonstrate definitive sarcomeric structure, cell and matrix deformation, contractile force, and electrical conduction. To show that functional myocardial tissue of human scale can be built on this platform, we then partially recellularized human whole heart scaffolds with human iPSC-derived cardiac myocytes. Under biomimetic culture, the seeded constructs developed force-generating human myocardial tissue, showed electrical conductivity, left ventricular pressure development, and metabolic function. Conclusions Native cardiac extracellular matrix scaffolds maintain matrix components and structure to support the seeding and engraftment of human iPS-derived cardiac myocytes, and enable the bioengineering of functional human myocardial-like tissue of multiple complexities. PMID:26503464

Predicting the required number of training samples. [for remotely sensed image data based on covariance matrix estimate quality criterion of normal distribution

NASA Technical Reports Server (NTRS)

Kalayeh, H. M.; Landgrebe, D. A.

1983-01-01

A criterion which measures the quality of the estimate of the covariance matrix of a multivariate normal distribution is developed. Based on this criterion, the necessary number of training samples is predicted. Experimental results which are used as a guide for determining the number of training samples are included. Previously announced in STAR as N82-28109

Analysis of Phospholipid Mixtures from Biological Tissues by Matrix-Assisted Laser Desorption and Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS): A Laboratory Experiment

ERIC Educational Resources Information Center

Eibisch, Mandy; Fuchs, Beate; Schiller, Jurgen; Sub, Rosmarie; Teuber, Kristin

2011-01-01

Matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS) is increasingly used to investigate the phospholipid (PL) compositions of tissues and body fluids, often without previous separation of the total mixture into the individual PL classes. Therefore, the questions of whether all PL classes are detectable…

Improved Dot Diffusion For Image Halftoning

DTIC Science & Technology

1999-01-01

The dot diffusion method for digital halftoning has the advantage of parallelism unlike the error diffusion method. The method was recently improved...by optimization of the so-called class matrix so that the resulting halftones are comparable to the error diffused halftones . In this paper we will...first review the dot diffusion method. Previously, 82 class matrices were used for dot diffusion method. A problem with this size of class matrix is

Nanoparticle-assisted laser desorption/ionization mass spectrometry: Novel sample preparation methods and nanoparticle screening for plant metabolite imaging

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

Yagnik, Gargey B.

The main goal of the presented research is development of nanoparticle based matrix-assisted laser desorption ionization-mass spectrometry (MALDI-MS). This dissertation includes the application of previously developed data acquisition methods, development of novel sample preparation methods, application and comparison of novel nanoparticle matrices, and comparison of two nanoparticle matrix application methods for MALDI-MS and MALDI-MS imaging.

Soy matrix drug delivery systems obtained by melt-processing techniques.

PubMed

Vaz, Cláudia M; van Doeveren, Patrick F N M; Reis, Rui L; Cunha, António M

2003-01-01

The aim of this study was to develop new soy protein drug delivery matrix systems by melt-processing techniques, namely, extrusion and injection moulding. The soy matrix systems with an encapsulated drug (theophylline, TH) were previously compounded by extrusion performed at two different pH values, (i) pH 4 (SIpDtp) and (ii) pH 7 (SIDtp), and further injection-moulded into a desired shape. During the extrusion process the matrixes SIDtp were also cross-linked with glyoxal (0.6X-SIDtp) and reinforced with a bioactive filler, hydroxylapatite (SI-HADtp). The obtained mouldings were used to study the drug-release mechanisms from the plastic soy-TH matrixes. In an isotonic saline solution (ISS) buffered at pH 5.0 (200 mM acetate buffer), the resulting release kinetics could be described using the Fick's second law of diffusion. Because the diffusion coefficients were found to be constant and the boundary conditions to be stationary, these systems are drug-diffusion controlled. Conversely, the dominant phenomena in an isotonic saline solution buffered at pH 7.4 (200 mM Tris/HCl buffer) are more complex. In fact, because of the higher polymer solubility, the resulting matrix is time-variant. So, the drug release is affected by swelling, drug diffusion, and polymer dissolution, being faster when compared to ISS-200 mM acetate buffer, pH 5.0. The changes in the formulation composition affecting the correspondent release rates were also investigated. At pH 7.4, increasing the cross-linking degree of the polymer matrix (via reaction with glyoxal or heat treatment) or decreasing the net charge (extruding at pH near its isoelectric point) led to lower release rates. The incorporation of ceramic filler caused the opposite effect. Because of the low solubility of the matrix at pH 5.0, no significant variations were detected with variations in the selected formulations. These systems, based on a nonstandard protein-based material, seem to be very promising to be used as carriers for drug delivery.

Electrothermal atomisation atomic absorption conditions and matrix modifications for determining antimony, arsenic, bismuth, cadmium, gallium, gold, indium, lead, molybdenum, palladium, platinum, selenium, silver, tellurium, thallium and tin following back-extraction of organic aminohalide extracts

USGS Publications Warehouse

Clark, J.R.

1986-01-01

A multi-element organic-extraction and back-extraction procedure, that had been developed previously to eliminate matrix interferences in the determination of a large number of trace elements in complex materials such as geological samples, produced organic and aqueous solutions that were complex. Electrothermal atomisation atomic absorption conditions and matrix modifications have been developed for 13 of the extracted elements (Ag, As, Au, Bi, Cd, Ga, In, Pb, Sb, Se, Sn, Te and Tl) that enhance sensitivity, alleviate problems resulting from the complex solutions and produce acceptable precision. Platinum, Pd and Mo can be determined without matrix modification directly on the original unstripped extracts.

An efficient matrix-matrix multiplication based antisymmetric tensor contraction engine for general order coupled cluster.

PubMed

Hanrath, Michael; Engels-Putzka, Anna

2010-08-14

In this paper, we present an efficient implementation of general tensor contractions, which is part of a new coupled-cluster program. The tensor contractions, used to evaluate the residuals in each coupled-cluster iteration are particularly important for the performance of the program. We developed a generic procedure, which carries out contractions of two tensors irrespective of their explicit structure. It can handle coupled-cluster-type expressions of arbitrary excitation level. To make the contraction efficient without loosing flexibility, we use a three-step procedure. First, the data contained in the tensors are rearranged into matrices, then a matrix-matrix multiplication is performed, and finally the result is backtransformed to a tensor. The current implementation is significantly more efficient than previous ones capable of treating arbitrary high excitations.

Counterbalancing anti-adhesive effects of Tenascin-C through fibronectin expression in endothelial cells.

PubMed

Radwanska, Agata; Grall, Dominique; Schaub, Sébastien; Divonne, Stéphanie Beghelli-de la Forest; Ciais, Delphine; Rekima, Samah; Rupp, Tristan; Sudaka, Anne; Orend, Gertraud; Van Obberghen-Schilling, Ellen

2017-10-06

Cellular fibronectin (FN) and tenascin-C (TNC) are prominent development- and disease-associated matrix components with pro- and anti-adhesive activity, respectively. Whereas both are present in the tumour vasculature, their functional interplay on vascular endothelial cells remains unclear. We have previously shown that basally-oriented deposition of a FN matrix restricts motility and promotes junctional stability in cultured endothelial cells and that this effect is tightly coupled to expression of FN. Here we report that TNC induces FN expression in endothelial cells. This effect counteracts the potent anti-adhesive activity of TNC and leads to the assembly of a dense highly-branched subendothelial matrix that enhances tubulogenic activity. These findings suggest that pro-angiogenic remodelling of the perivascular matrix may involve TNC-induced upregulation of FN in endothelial cells.

Quorum-sensing regulation of the biofilm matrix genes (pel) of Pseudomonas aeruginosa.

PubMed

Sakuragi, Yumiko; Kolter, Roberto

2007-07-01

Quorum sensing (QS) has been previously shown to play an important role in the development of Pseudomonas aeruginosa biofilms (D. G. Davies et al., Science 280:295-298, 1998). Although QS regulation of swarming and DNA release has been shown to play important roles in biofilm development, regulation of genes directly involved in biosynthesis of biofilm matrix has not been described. Here, transcription of the pel operon, essential for the production of a glucose-rich matrix exopolysaccharide, is shown to be greatly reduced in lasI and rhlI mutants. Chemical complementation of the lasI mutant with 3-oxo-dodecanoyl homoserine lactone restores pel transcription to the wild-type level and biofilm formation ability. These findings thus connect QS signaling and transcription of genes responsible for biofilm matrix biosynthesis.

Moderate (2%, v/v) Ethanol Feeding Alters Hepatic Wound Healing after Acute Carbon Tetrachloride Exposure in Mice

PubMed Central

Deshpande, Krutika T.; Liu, Shinlan; McCracken, Jennifer M.; Jiang, Lu; Gaw, Ta Ehpaw; Kaydo, Lindsey N.; Richard, Zachary C.; O’Neil, Maura F.; Pritchard, Michele T.

2016-01-01

Wound healing consists of three overlapping phases: inflammation, proliferation, and matrix synthesis and remodeling. Prolonged alcohol abuse can cause liver fibrosis due to deregulated matrix remodeling. Previous studies demonstrated that moderate ethanol feeding enhances liver fibrogenic markers and frank fibrosis independent of differences in CCl4-induced liver injury. Our objective was to determine whether or not other phases of the hepatic wound healing response were affected by moderate ethanol after CCl4 exposure. Mice were fed moderate ethanol (2% v/v) for two days and then were exposed to CCl4 and euthanized 24–96 h later. Liver injury was not different between pair- and ethanol-fed mice; however, removal of necrotic tissue was delayed after CCl4-induced liver injury in ethanol-fed mice. Inflammation, measured by TNFα mRNA and protein and hepatic Ly6c transcript accumulation, was reduced and associated with enhanced hepatocyte apoptosis after ethanol feeding. Hepatocytes entered the cell cycle equivalently in pair- and ethanol-fed mice after CCl4 exposure, but hepatocyte proliferation was prolonged in livers from ethanol-fed mice. CCl4-induced hepatic stellate cell activation was increased and matrix remodeling was prolonged in ethanol-fed mice compared to controls. Taken together, moderate ethanol affected each phase of the wound healing response to CCl4. These data highlight previously unknown effects of moderate ethanol exposure on hepatic wound healing after acute hepatotoxicant exposure. PMID:26751492

Characterization and quantification of grape variety by means of shikimic acid concentration and protein fingerprint in still white wines.

PubMed

Chabreyrie, David; Chauvet, Serge; Guyon, François; Salagoïty, Marie-Hélène; Antinelli, Jean-François; Medina, Bernard

2008-08-27

Protein profiles, obtained by high-performance capillary electrophoresis (HPCE) on white wines previously dialyzed, combined with shikimic acid concentration and multivariate analysis, were used for the determination of grape variety composition of a still white wine. Six varieties were studied through monovarietal wines elaborated in the laboratory: Chardonnay (24 samples), Chenin (24), Petit Manseng (7), Sauvignon (37), Semillon (24), and Ugni Blanc (9). Homemade mixtures were elaborated from authentic monovarietal wines according to a Plackett-Burman sampling plan. After protein peak area normalization, a matrix was elaborated containing protein results of wines (mixtures and monovarietal). Partial least-squares processing was applied to this matrix allowing the elaboration of a model that provided a varietal quantification precision of around 20% for most of the grape varieties studied. The model was applied to commercial samples from various geographical origins, providing encouraging results for control purposes.

Depth estimation of multi-layered impact damage in PMC using lateral thermography

NASA Astrophysics Data System (ADS)

Whitlow, Travis; Kramb, Victoria; Reibel, Rick; Dierken, Josiah

2018-04-01

Characterization of impact damage in polymer matrix composites (PMCs) continues to be a challenge due to the complex internal structure of the material. Nondestructive characterization approaches such as normal incident immersion ultrasound and flash thermography are sensitive to delamination damage, but do not provide information regarding damage obscured by the delaminations. Characterization of material state below a delamination requires a technique which is sensitive to in-plane damage modes such as matrix cracking and fiber breakage. Previous studies of the lateral heat flow through a composite laminate showed that the diffusion time was sensitive to the depth of the simulated damage zone. The current study will further evaluate the lateral diffusion model to provide sensitivity limits for the modeled flaw dimensions. Comparisons between the model simulations and experimental data obtained using a concentrated heat source and machined targets will also be presented.

Characterising encapsulated nuclear waste using cosmic-ray muon tomography

NASA Astrophysics Data System (ADS)

Clarkson, A.; Hamilton, D. J.; Hoek, M.; Ireland, D. G.; Johnstone, J. R.; Kaiser, R.; Keri, T.; Lumsden, S.; Mahon, D. F.; McKinnon, B.; Murray, M.; Nutbeam-Tuffs, S.; Shearer, C.; Yang, G.; Zimmerman, C.

2015-03-01

Tomographic imaging techniques using the Coulomb scattering of cosmic-ray muons have been shown previously to successfully identify and characterise low- and high-Z materials within an air matrix using a prototype scintillating-fibre tracker system. Those studies were performed as the first in a series to assess the feasibility of this technology and image reconstruction techniques in characterising the potential high-Z contents of legacy nuclear waste containers for the U.K. Nuclear Industry. The present work continues the feasibility study and presents the first images reconstructed from experimental data collected using this small-scale prototype system of low- and high-Z materials encapsulated within a concrete-filled stainless-steel container. Clear discrimination is observed between the thick steel casing, the concrete matrix and the sample materials assayed. These reconstructed objects are presented and discussed in detail alongside the implications for future industrial scenarios.

Morphological elucidation of basal ganglia circuits contributing reward prediction

PubMed Central

Fujiyama, Fumino; Takahashi, Susumu; Karube, Fuyuki

2015-01-01

Electrophysiological studies in monkeys have shown that dopaminergic neurons respond to the reward prediction error. In addition, striatal neurons alter their responsiveness to cortical or thalamic inputs in response to the dopamine signal, via the mechanism of dopamine-regulated synaptic plasticity. These findings have led to the hypothesis that the striatum exhibits synaptic plasticity under the influence of the reward prediction error and conduct reinforcement learning throughout the basal ganglia circuits. The reinforcement learning model is useful; however, the mechanism by which such a process emerges in the basal ganglia needs to be anatomically explained. The actor–critic model has been previously proposed and extended by the existence of role sharing within the striatum, focusing on the striosome/matrix compartments. However, this hypothesis has been difficult to confirm morphologically, partly because of the complex structure of the striosome/matrix compartments. Here, we review recent morphological studies that elucidate the input/output organization of the striatal compartments. PMID:25698913

A nutrient mixture inhibits glioblastoma xenograft U-87 MG growth in male nude mice.

PubMed

Roomi, M W; Kalinovsky, T; Rath, M; Niedzwiecki, A

2016-03-01

Brain tumors are highly aggressive tumors characterized by secretions of high levels of matrix metalloproteinase-2 and -9, leading to tumor growth, invasion and metastasis by digesting the basement membrane and extracellular matrix components. We previously demonstrated the effectiveness of a nutrient mixture (NM) containing ascorbic acid, lysine, proline, and green tea extract in vitro: on activity of urokinase plasminogen activator, matrix metalloproteinases and TIMPs in various human glioblastoma (LN-18, T-98G and A-172) cell lines and on glioblastoma A-172 cell proliferation and Matrigel invasion. Our main objective in this study was to investigate the effect of the NM in vivo on human glioblastoma U-87 MG cell line. Athymic male nude mice inoculated with 3·10(6) U-87 MG cells subcutaneously and were fed a regular diet or a regular diet supplemented with 0.5% NM. Four weeks later, the mice were sacrificed, the tumors were weighed and measured. The samples were studied histologically. NM inhibited tumor weight and tumor burden by 53% (p = 0.015) and 48% (p = 0.010), respectively. These results suggest the therapeutic potential of NM as an adjuvant in the treatment of glioblastoma.

Fluctuation-dissipation theory of input-output interindustrial relations

NASA Astrophysics Data System (ADS)

Iyetomi, Hiroshi; Nakayama, Yasuhiro; Aoyama, Hideaki; Fujiwara, Yoshi; Ikeda, Yuichi; Souma, Wataru

2011-01-01

In this study, the fluctuation-dissipation theory is invoked to shed light on input-output interindustrial relations at a macroscopic level by its application to indices of industrial production (IIP) data for Japan. Statistical noise arising from finiteness of the time series data is carefully removed by making use of the random matrix theory in an eigenvalue analysis of the correlation matrix; as a result, two dominant eigenmodes are detected. Our previous study successfully used these two modes to demonstrate the existence of intrinsic business cycles. Here a correlation matrix constructed from the two modes describes genuine interindustrial correlations in a statistically meaningful way. Furthermore, it enables us to quantitatively discuss the relationship between shipments of final demand goods and production of intermediate goods in a linear response framework. We also investigate distinctive external stimuli for the Japanese economy exerted by the current global economic crisis. These stimuli are derived from residuals of moving-average fluctuations of the IIP remaining after subtracting the long-period components arising from inherent business cycles. The observation reveals that the fluctuation-dissipation theory is applicable to an economic system that is supposed to be far from physical equilibrium.

Matrix metalloproteinase-2 plays a critical role in overload induced skeletal muscle hypertrophy.

PubMed

Zhang, Qia; Joshi, Sunil K; Lovett, David H; Zhang, Bryon; Bodine, Sue; Kim, Hubert T; Liu, Xuhui

2014-01-01

extracellular matrix (ECM) components are instrumental in maintaining homeostasis and muscle fiber functional integrity. Skeletal muscle hypertrophy is associated with ECM remodeling. Specifically, recent studies have reported the involvement of matrix metalloproteinases (MMPs) in muscle ECM remodeling. However, the functional role of MMPs in muscle hypertrophy remains largely unknown. in this study, we examined the role of MMP-2 in skeletal muscle hypertrophy using a previously validated method where the plantaris muscle of mice were subjected to mechanical overload due to the surgical removal of synergist muscles (gastrocnemius and soleus). following two weeks of overload, we observed a significant increase in MMP-2 activity and up-regulation of ECM components and remodeling enzymes in the plantaris muscles of wild-type mice. However, MMP-2 knockout mice developed significantly less hypertrophy and ECM remodeling in response to overload compared to their wild-type littermates. Investigation of protein synthesis rate and Akt/mTOR signaling revealed no difference between wild-type and MMP-2 knockout mice, suggesting that a difference in hypertrophy was independent of protein synthesis. taken together, our results suggest that MMP-2 is a key mediator of ECM remodeling in the setting of skeletal muscle hypertrophy.

Matrix metalloproteinase-2 plays a critical role in overload induced skeletal muscle hypertrophy.

PubMed

Zhang, Qia; Joshi, Sunil K; Lovett, David H; Zhang, Bryon; Bodine, Sue; Kim, Hubert; Liu, Xuhui

2014-07-01

extracellular matrix (ECM) components are instrumental in maintaining homeostasis and muscle fiber functional integrity. Skeletal muscle hypertrophy is associated with ECM remodeling. Specifically, recent studies have reported the involvement of matrix metalloproteinases (MMPs) in muscle ECM remodeling. However, the functional role of MMPs in muscle hypertrophy remains largely unknown. in this study, we examined the role of MMP-2 in skeletal muscle hypertrophy using a previously validated method where the plantaris muscle of mice were subjected to mechanical overload due to the surgical removal of synergist muscles (gastrocnemius and soleus). following two weeks of overload, we observed a significant increase in MMP-2 activity and up-regulation of ECM components and remodeling enzymes in the plantaris muscles of wild-type mice. However, MMP-2 knockout mice developed significantly less hypertrophy and ECM remodeling in response to overload compared to their wild-type littermates. Investigation of protein synthesis rate and Akt/mTOR signaling revealed no difference between wild-type and MMP-2 knockout mice, suggesting that a difference in hypertrophy was independent of protein synthesis. taken together, our results suggest that MMP-2 is a key mediator of ECM remodeling in the setting of skeletal muscle hypertrophy.

The impact of yeast fermentation on dough matrix properties.

PubMed

Rezaei, Mohammad N; Jayaram, Vinay B; Verstrepen, Kevin J; Courtin, Christophe M

2016-08-01

Most studies on dough properties are performed on yeastless dough to exclude the complicating, time-dependent effect of yeast. Baker's yeast, however, impacts dough matrix properties during fermentation, probably through the production of primary (CO2 and ethanol) and secondary (glycerol, acetic acid and succinic acid) metabolites. The aim of this study is to obtain a better understanding of the changes in yeasted dough behavior introduced by fermentation, by investigating the impact of yeast fermentation on Farinograph dough consistency, dough spread, Kieffer rig dough extensibility and gluten agglomeration behavior in a fermented dough-batter gluten starch separation system. Results show that fermentation leads to a dough with less flow and lower extensibility that breaks more easily under stress and strain. The dough showed less elastic and more plastic deformation behavior. Gluten agglomerates were smaller for yeasted dough than for the unyeasted control. These changes probably have to be attributed to metabolites generated during fermentation. Indeed, organic acids and also ethanol in concentrations produced by yeast were previously shown to have similar effects in yeastless dough. These findings imply the high importance of yeast fermentation metabolites on dough matrix properties in industrial bread production. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

A reassessment of the taxonomic position of mesosaurs, and a surprising phylogeny of early amniotes

NASA Astrophysics Data System (ADS)

Laurin, Michel; Piñeiro, Graciela H.

2017-11-01

We reassess the phylogenetic position of mesosaurs by using a data matrix that is updated and slightly expanded from a matrix that the first author published in 1995 with his former thesis advisor. The revised matrix, which incorporates anatomical information published in the last twenty years and observations on several mesosaur specimens (mostly from Uruguay) includes seventeen terminal taxa and 129 characters (four more taxa and five more characters than the original matrix from 1995). The new matrix also differs by incorporating more ordered characters (all morphoclines were ordered). Parsimony analyses in PAUP 4 using the branch and bound algorithm show that the new matrix supports a position of mesosaurs at the very base of Sauropsida, as suggested by the first author in 1995. The exclusion of mesosaurs from a less inclusive clade of sauropsids is supported by a Bremer (Decay) index of 4 and a bootstrap frequency of 66%, both of which suggest that this result is moderately robust. The most parsimonious trees include some unexpected results, such as placing the anapsid reptile Paleothyris near the base of diapsids, and all of parareptiles as the sister-group of younginiforms (the most crownward diapsids included in the analyses). Turtles are placed among parareptiles, as the sister-group of pareiasaurs (and in diapsids, given that parareptiles are nested within diapsids). This unexpected result offers a potential solution to the long-lasting controversy about the position of turtles because previous studies viewed a position among diapsids and among parareptiles as mutually exclusive alternatives.

Composite propellant combustion with low aluminum agglomeration

NASA Astrophysics Data System (ADS)

Mullen, Jessica Christine

Aluminum behavior---accumulation, agglomeration and ignition---is studied in a unique, wide-distribution, ammonium perchlorate/hydroxyl-terminated polybutadiene (AP/HTPB) propellant formulation that results in low Al agglomeration, even at low pressures (1--30 atm). Variations in formulation---such as fine-AP/binder ratio, Al particle size, Al loading, coarse-AP size---are also examined. A fuel-rich, oxygenated binder matrix highly loaded with fine (2-mum) AP (FAP) at 75/25:FAP/binder (by mass) is found to have premixed flame conditions that produce minimal agglomeration (without ignition) of 15-mum Al. Coarse AP (CAP) is added to the system in the form of either particles (200 or 400 mum) or pressed-AP laminates (simulated CAP). In the 2-D laminate system the CAP/oxyfuel-matrix flame structure is seen to be similar to that previously described for non-aluminized laminates with split (diffusion) and merged (partially-premixed) flame regimes, depending on pressure and fuel-matrix thickness. Both laminate and particulate systems show that with CAP present, Al can agglomerate more extensively on CAP via lateral surface migration from fuel matrix to the CAP region. The particulate CAP system also shows that Al can accumulate/agglomerate via settling on CAP from above (in the direction of burning). Both systems, but more clearly the 2-D laminates, show that with CAP present, Al is ignited by the outer CAP/fuel-matrix canopy flames. Thus, a propellant formulation is proposed for reducing overall Al agglomeration through intrinsically reduced agglomeration in the fuel-matrix and a reduced number of CAP-particle agglomerates via higher FAP/CAP ratio.

Size-dependent penetrant diffusion in polymer glasses.

PubMed

Meng, Dong; Zhang, Kai; Kumar, Sanat K

2018-05-18

Molecular Dynamics simulations are used to understand the underpinning basis of the transport of gas-like solutes in deeply quenched polymeric glasses. As found in previous work, small solutes, with sizes smaller than 0.15 times the chain monomer size, move as might be expected in a medium with large pores. In contrast, the motion of larger solutes is activated and is strongly facilitated by matrix motion. In particular, solute motion is coupled to the local elastic fluctuations of the matrix as characterized by the Debye-Waller factor. While similar ideas have been previously proposed for the viscosity of supercooled liquids above their glass transition, to our knowledge, this is the first illustration of this concept in the context of solute mass transport in deeply quenched polymer glasses.

Prediction of thermal cycling induced cracking in polmer matrix composites

NASA Technical Reports Server (NTRS)

Mcmanus, Hugh L.

1994-01-01

The work done in the period August 1993 through February 1994 on the 'Prediction of Thermal Cycling Induced Cracking In Polymer Matrix Composites' program is summarized. Most of the work performed in this period, as well as the previous one, is described in detail in the attached Master's thesis, 'Analysis of Thermally Induced Damage in Composite Space Structures,' by Cecelia Hyun Seon Park. Work on a small thermal cycling and aging chamber was concluded in this period. The chamber was extensively tested and calibrated. Temperatures can be controlled very precisely, and are very uniform in the test chamber. Based on results obtained in the previous period of this program, further experimental progressive cracking studies were carried out. The laminates tested were selected to clarify the differences between the behaviors of thick and thin ply layers, and to explore other variables such as stacking sequence and scaling effects. Most specimens tested were made available from existing stock at Langley Research Center. One laminate type had to be constructed from available prepreg material at Langley Research Center. Specimens from this laminate were cut and prepared at MIT. Thermal conditioning was carried out at Langley Research Center, and at the newly constructed MIT facility. Specimens were examined by edge inspection and by crack configuration studies, in which specimens were sanded down in order to examine the distribution of cracks within the specimens. A method for predicting matrix cracking due to decreasing temperatures and/or thermal cycling in all plies of an arbitrary laminate was implemented as a computer code. The code also predicts changes in properties due to the cracking. Extensive correlations between test results and code predictions were carried out. The computer code was documented and is ready for distribution.

Strong synergistic effects in PLA/PCL blends: Impact of PLA matrix viscosity.

PubMed

Ostafinska, Aleksandra; Fortelný, Ivan; Hodan, Jiří; Krejčíková, Sabina; Nevoralová, Martina; Kredatusová, Jana; Kruliš, Zdeněk; Kotek, Jiří; Šlouf, Miroslav

2017-05-01

Blends of two biodegradable polymers, poly(lactic acid) (PLA) and poly(ϵ-caprolactone) (PCL), with strong synergistic improvement in mechanical performance were prepared by melt-mixing using the optimized composition (80/20) and the optimized preparation procedure (a melt-mixing followed by a compression molding) according to our previous study. Three different PLA polymers were employed, whose viscosity decreased in the following order: PLC ≈ PLA1 > PLA2 > PLA3. The blends with the highest viscosity matrix (PLA1/PCL) exhibited the smallest PCL particles (d∼0.6μm), an elastic-plastic stable fracture (as determined from instrumented impact testing) and the strongest synergistic improvement in toughness (>16× with respect to pure PLA, exceeding even the toughness of pure PCL). According to the available literature, this was the highest toughness improvement in non-compatiblized PLA/PCL blends ever achieved. The decrease in the matrix viscosity resulted in an increase in the average PCL particle size and a dramatic decrease in the overall toughness: the completely stable fracture (for PLA1/PCL) changed to the stable fracture followed by unstable crack propagation (for PLA2/PCL) and finally to the completely brittle fracture (for PLA3/PCL). The stiffness of all blends remained at well acceptable level, slightly above the theoretical predictions based on the equivalent box model. Despite several previous studies, the results confirmed that PLA and PCL could behave as compatible polymers, but the final PLA/PCL toughness is extremely sensitive to the PCL particle size distribution, which is influenced by both processing conditions and PLA viscosity. PLA/PCL blends with high stiffness (due to PLA) and toughness (due to PCL) are very promising materials for medical applications, namely for the bone tissue engineering. Copyright © 2017 Elsevier Ltd. All rights reserved.

Efficient conjugate gradient algorithms for computation of the manipulator forward dynamics

NASA Technical Reports Server (NTRS)

Fijany, Amir; Scheid, Robert E.

1989-01-01

The applicability of conjugate gradient algorithms for computation of the manipulator forward dynamics is investigated. The redundancies in the previously proposed conjugate gradient algorithm are analyzed. A new version is developed which, by avoiding these redundancies, achieves a significantly greater efficiency. A preconditioned conjugate gradient algorithm is also presented. A diagonal matrix whose elements are the diagonal elements of the inertia matrix is proposed as the preconditioner. In order to increase the computational efficiency, an algorithm is developed which exploits the synergism between the computation of the diagonal elements of the inertia matrix and that required by the conjugate gradient algorithm.

Pattern identification in time-course gene expression data with the CoGAPS matrix factorization.

PubMed

Fertig, Elana J; Stein-O'Brien, Genevieve; Jaffe, Andrew; Colantuoni, Carlo

2014-01-01

Patterns in time-course gene expression data can represent the biological processes that are active over the measured time period. However, the orthogonality constraint in standard pattern-finding algorithms, including notably principal components analysis (PCA), confounds expression changes resulting from simultaneous, non-orthogonal biological processes. Previously, we have shown that Markov chain Monte Carlo nonnegative matrix factorization algorithms are particularly adept at distinguishing such concurrent patterns. One such matrix factorization is implemented in the software package CoGAPS. We describe the application of this software and several technical considerations for identification of age-related patterns in a public, prefrontal cortex gene expression dataset.

Comprehensive Thematic T-Matrix Reference Database: A 2015-2017 Update

NASA Technical Reports Server (NTRS)

Mishchenko, Michael I.; Zakharova, Nadezhda; Khlebtsov, Nikolai G.; Videen, Gorden; Wriedt, Thomas

2017-01-01

The T-matrix method pioneered by Peter C. Waterman is one of the most versatile and efficient numerically exact computer solvers of the time-harmonic macroscopic Maxwell equations. It is widely used for the computation of electromagnetic scattering by single and composite particles, discrete random media, periodic structures (including metamaterials), and particles in the vicinity of plane or rough interfaces separating media with different refractive indices. This paper is the eighth update to the comprehensive thematic database of peer-reviewed T-matrix publications initiated in 2004 and lists relevant publications that have appeared since 2015. It also references a small number of earlier publications overlooked previously.

Comprehensive thematic T-matrix reference database: A 2015-2017 update

NASA Astrophysics Data System (ADS)

Mishchenko, Michael I.; Zakharova, Nadezhda T.; Khlebtsov, Nikolai G.; Videen, Gorden; Wriedt, Thomas

2017-11-01

The T-matrix method pioneered by Peter C. Waterman is one of the most versatile and efficient numerically exact computer solvers of the time-harmonic macroscopic Maxwell equations. It is widely used for the computation of electromagnetic scattering by single and composite particles, discrete random media, periodic structures (including metamaterials), and particles in the vicinity of plane or rough interfaces separating media with different refractive indices. This paper is the eighth update to the comprehensive thematic database of peer-reviewed T-matrix publications initiated in 2004 and lists relevant publications that have appeared since 2015. It also references a small number of earlier publications overlooked previously.

Surface fuel treatments in young, regenerating stands affect wildfire severity in a mixed conifer forest, eastside Cascade Range, Washington, USA

Treesearch

Christina Lyons-Tinsley; David L. Peterson

2012-01-01

Previous studies have debated the flammability of young regenerating stands, especially those in a matrix of mature forest, and no consensus has emerged as to whether young stands are inherently prone to high-severity wildfire. This topic has recently been addressed using spatial imagery, and weak inferences were made given the scale mismatch between the coarse...

High temperature heat exchanger studies for applications to gas turbines

NASA Astrophysics Data System (ADS)

Min, June Kee; Jeong, Ji Hwan; Ha, Man Yeong; Kim, Kui Soon

2009-12-01

Growing demand for environmentally friendly aero gas-turbine engines with lower emissions and improved specific fuel consumption can be met by incorporating heat exchangers into gas turbines. Relevant researches in such areas as the design of a heat exchanger matrix, materials selection, manufacturing technology, and optimization by a variety of researchers have been reviewed in this paper. Based on results reported in previous studies, potential heat exchanger designs for an aero gas turbine recuperator, intercooler, and cooling-air cooler are suggested.

Silencing by nuclear matrix attachment distinguishes cell-type specificity: association with increased proliferation capacity.

PubMed

Linnemann, Amelia K; Krawetz, Stephen A

2009-05-01

DNA loop organization by nuclear scaffold/matrix attachment is a key regulator of gene expression that may provide a means to modulate phenotype. We have previously shown that attachment of genes to the NaCl-isolated nuclear matrix correlates with their silencing in HeLa cells. In contrast, expressed genes were associated with the lithium 3,5-diiodosalicylate (LIS)-isolated nuclear scaffold. To define their role in determining phenotype matrix attached regions (MARs) on human chromosomes 14-18 were identified as a function of expression in a primary cell line. The locations of MARs in aortic adventitial fibroblast (AoAF) cells were very stable (r = 0.909) and 96% of genes attached at MARs are silent (P < 0.001). Approximately one-third of the genes uniquely expressed in AoAF cells were associated with the HeLa cell nuclear matrix and silenced. Comparatively, 81% were associated with the AoAF cell nuclear scaffold (P < 0.001) and expressed. This suggests that nuclear scaffold/matrix association mediates a portion of cell type-specific gene expression thereby modulating phenotype. Interestingly, nuclear matrix attachment and thus silencing of specific genes that regulate proliferation and maintain the integrity of the HeLa cell genome suggests that transformation may at least in part be achieved through aberrant nuclear matrix attachment.

A proteinaceous organic matrix regulates carbonate mineral production in the marine teleost intestine

PubMed Central

Schauer, Kevin L.; LeMoine, Christophe M. R.; Pelin, Adrian; Corradi, Nicolas; Warren, Wesley C.; Grosell, Martin

2016-01-01

Marine teleost fish produce CaCO3 in their intestine as part of their osmoregulatory strategy. This precipitation is critical for rehydration and survival of the largest vertebrate group on earth, yet the molecular mechanisms that regulate this reaction are unknown. Here, we isolate and characterize an organic matrix associated with the intestinal precipitates produced by Gulf toadfish (Opsanus beta). Toadfish precipitates were purified using two different methods, and the associated organic matrix was extracted. Greater than 150 proteins were identified in the isolated matrix by mass spectrometry and subsequent database searching using an O. beta transcriptomic sequence library produced here. Many of the identified proteins were enriched in the matrix compared to the intestinal fluid, and three showed no substantial homology to any previously characterized protein in the NCBI database. To test the functionality of the isolated matrix, a micro-modified in vitro calcification assay was designed, which revealed that low concentrations of isolated matrix substantially promoted CaCO3 production, where high concentrations showed an inhibitory effect. High concentrations of matrix also decreased the incorporation of magnesium into the forming mineral, potentially providing an explanation for the variability in magnesium content observed in precipitates produced by different fish species. PMID:27694946

Amorphization of the interaction products in U-Mo/Al dispersion fuel during irradiation

NASA Astrophysics Data System (ADS)

Ryu, Ho Jin; Kim, Yeon Soo; Hofman, G. L.

2009-04-01

The microstructures of the product resulting from interaction between U-Mo fuel particles and the Al matrix in U-Mo/Al dispersion fuel are discussed. We analyzed the available characterization results for the Al matrix dispersion fuels from both the out-of-pile and in-pile tests and examined the difference between these results. The morphology of pores that form in the interaction products during irradiation is similar to the porosity previously observed in irradiation-induced amorphized uranium compounds. The available diffraction studies for the interaction products formed in both the out-of-pile and in-pile tests are analyzed. We have concluded that the interaction products in the U-Mo/Al dispersion fuel are formed as an amorphous state or become amorphous during irradiation, depending on the irradiation conditions.

Algebraic Bethe ansatz for the XXZ Heisenberg spin chain with triangular boundaries and the corresponding Gaudin model

NASA Astrophysics Data System (ADS)

Manojlović, N.; Salom, I.

2017-10-01

The implementation of the algebraic Bethe ansatz for the XXZ Heisenberg spin chain in the case, when both reflection matrices have the upper-triangular form is analyzed. The general form of the Bethe vectors is studied. In the particular form, Bethe vectors admit the recurrent procedure, with an appropriate modification, used previously in the case of the XXX Heisenberg chain. As expected, these Bethe vectors yield the strikingly simple expression for the off-shell action of the transfer matrix of the chain as well as the spectrum of the transfer matrix and the corresponding Bethe equations. As in the XXX case, the so-called quasi-classical limit gives the off-shell action of the generating function of the corresponding trigonometric Gaudin Hamiltonians with boundary terms.

Computational Investigation of Structured Shocks in Al/SiC-Particulate Metal-Matrix Composites

DTIC Science & Technology

2011-06-01

used to implement the dynamic-mixture model into the VUMAT user-material subroutine of ABAQUS /Explicit. Owing to the attendant large strains and...that the residual thermal - expansion effects are more pronounced in the aluminium-matrix than in SiC-particulates. This finding is consistent with the...simple waves (CSWs) (Davison, 2008). . In accordance with the previously observed larger thermal - expansion effects in Al, Figure 5(b) shows that the

Complex torso reconstruction with human acellular dermal matrix: long-term clinical follow-up.

PubMed

Nemeth, Nicole L; Butler, Charles E

2009-01-01

Although reports have demonstrated good early outcomes with human acellular dermal matrix even when used for complex, contaminated defects, no long-term outcomes have been reported. The authors reviewed the long-term outcomes of 13 patients who had complex torso reconstructions that included human acellular dermal matrix. All patients were at increased risk for mesh-related complications. Eight patients died as a result of progression of their oncologic disease at a mean of 258 days postoperatively. The mean follow-up for the remaining five patients was 43.7 months. Six patients had early complications (none were human acellular dermal matrix-related) and were reported on previously. Two patients had developed complications since the initial report. One patient developed a flap donor-site seroma remote from the reconstruction site, and another developed a recurrent ventral hernia. No patients have required additional surgery for human acellular dermal matrix-related complications. This follow-up report indicates that human acellular dermal matrix repair of large, complex torso defects can result in good long-term outcomes even when patients are at high risk for mesh-related complications.

A matrix-inversion method for gamma-source mapping from gamma-count data

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

Adsley, Ian; Burgess, Claire; Bull, Richard K

In a previous paper it was proposed that a simple matrix inversion method could be used to extract source distributions from gamma-count maps, using simple models to calculate the response matrix. The method was tested using numerically generated count maps. In the present work a 100 kBq Co{sup 60} source has been placed on a gridded surface and the count rate measured using a NaI scintillation detector. The resulting map of gamma counts was used as input to the matrix inversion procedure and the source position recovered. A multi-source array was simulated by superposition of several single-source count maps andmore » the source distribution was again recovered using matrix inversion. The measurements were performed for several detector heights. The effects of uncertainties in source-detector distances on the matrix inversion method are also examined. The results from this work give confidence in the application of the method to practical applications, such as the segregation of highly active objects amongst fuel-element debris. (authors)« less

Matrix-free mass spectrometric imaging using laser desorption ionisation Fourier transform ion cyclotron resonance mass spectrometry

PubMed Central

Goodwin, Richard J A; Pitt, Andrew R; Harrison, David; Weidt, Stefan K; Langridge-Smith, Pat R R; Barrett, Michael P; Logan Mackay, C

2011-01-01

Mass spectrometry imaging (MSI) is a powerful tool in metabolomics and proteomics for the spatial localization and identification of pharmaceuticals, metabolites, lipids, peptides and proteins in biological tissues. However, sample preparation remains a crucial variable in obtaining the most accurate distributions. Common washing steps used to remove salts, and solvent-based matrix application, allow analyte spreading to occur. Solvent-free matrix applications can reduce this risk, but increase the possibility of ionisation bias due to matrix adhesion to tissue sections. We report here the use of matrix-free MSI using laser desorption ionisation performed on a 12 T Fourier transform ion cyclotron resonance (FTICR) mass spectrometer. We used unprocessed tissue with no post-processing following thaw-mounting on matrix-assisted laser desorption ionisation (MALDI) indium-tin oxide (ITO) target plates. The identification and distribution of a range of phospholipids in mouse brain and kidney sections are presented and compared with previously published MALDI time-of-flight (TOF) MSI distributions. Copyright © 2011 John Wiley & Sons, Ltd. PMID:21416534

Matrix Optical Absorption in UV-MALDI MS

NASA Astrophysics Data System (ADS)

Robinson, Kenneth N.; Steven, Rory T.; Bunch, Josephine

2018-03-01

In ultraviolet matrix-assisted laser desorption/ionization mass spectrometry (UV-MALDI MS) matrix compound optical absorption governs the uptake of laser energy, which in turn has a strong influence on experimental results. Despite this, quantitative absorption measurements are lacking for most matrix compounds. Furthermore, despite the use of UV-MALDI MS to detect a vast range of compounds, investigations into the effects of laser energy have been primarily restricted to single classes of analytes. We report the absolute solid state absorption spectra of the matrix compounds α-cyano-4-hydroxycinnamic acid (CHCA), para-nitroaniline (PNA), 2-mercaptobenzothiazole (MBT), 2,5-dihydroxybenzoic acid (2,5-DHB), and 2,4,6-trihydroxyacetophenone (THAP). The desorption/ionization characteristics of these matrix compounds with respect to laser fluence was investigated using mixed systems of matrix with either angiotensin II, PC(34:1) lipid standard, or haloperidol, acting as representatives for typical classes of analyte encountered in UV-MALDI MS. The first absolute solid phase spectra for PNA, MBT, and THAP are reported; additionally, inconsistencies between previously published spectra for CHCA are resolved. In light of these findings, suggestions are made for experimental optimization with regards to matrix and laser wavelength selection. The relationship between matrix optical cross-section and wavelength-dependant threshold fluence, fluence of maximum ion yield, and R, a new descriptor for the change in ion intensity with fluence, are described. A matrix cross-section of 1.3 × 10-17 cm-2 was identified as a potential minimum for desorption/ionization of analytes.

Matrix Optical Absorption in UV-MALDI MS.

PubMed

Robinson, Kenneth N; Steven, Rory T; Bunch, Josephine

2018-03-01

In ultraviolet matrix-assisted laser desorption/ionization mass spectrometry (UV-MALDI MS) matrix compound optical absorption governs the uptake of laser energy, which in turn has a strong influence on experimental results. Despite this, quantitative absorption measurements are lacking for most matrix compounds. Furthermore, despite the use of UV-MALDI MS to detect a vast range of compounds, investigations into the effects of laser energy have been primarily restricted to single classes of analytes. We report the absolute solid state absorption spectra of the matrix compounds α-cyano-4-hydroxycinnamic acid (CHCA), para-nitroaniline (PNA), 2-mercaptobenzothiazole (MBT), 2,5-dihydroxybenzoic acid (2,5-DHB), and 2,4,6-trihydroxyacetophenone (THAP). The desorption/ionization characteristics of these matrix compounds with respect to laser fluence was investigated using mixed systems of matrix with either angiotensin II, PC(34:1) lipid standard, or haloperidol, acting as representatives for typical classes of analyte encountered in UV-MALDI MS. The first absolute solid phase spectra for PNA, MBT, and THAP are reported; additionally, inconsistencies between previously published spectra for CHCA are resolved. In light of these findings, suggestions are made for experimental optimization with regards to matrix and laser wavelength selection. The relationship between matrix optical cross-section and wavelength-dependant threshold fluence, fluence of maximum ion yield, and R, a new descriptor for the change in ion intensity with fluence, are described. A matrix cross-section of 1.3 × 10 -17 cm -2 was identified as a potential minimum for desorption/ionization of analytes. Graphical Abstract ᅟ.

Quadratic canonical transformation theory and higher order density matrices.

PubMed

Neuscamman, Eric; Yanai, Takeshi; Chan, Garnet Kin-Lic

2009-03-28

Canonical transformation (CT) theory provides a rigorously size-extensive description of dynamic correlation in multireference systems, with an accuracy superior to and cost scaling lower than complete active space second order perturbation theory. Here we expand our previous theory by investigating (i) a commutator approximation that is applied at quadratic, as opposed to linear, order in the effective Hamiltonian, and (ii) incorporation of the three-body reduced density matrix in the operator and density matrix decompositions. The quadratic commutator approximation improves CT's accuracy when used with a single-determinant reference, repairing the previous formal disadvantage of the single-reference linear CT theory relative to singles and doubles coupled cluster theory. Calculations on the BH and HF binding curves confirm this improvement. In multireference systems, the three-body reduced density matrix increases the overall accuracy of the CT theory. Tests on the H(2)O and N(2) binding curves yield results highly competitive with expensive state-of-the-art multireference methods, such as the multireference Davidson-corrected configuration interaction (MRCI+Q), averaged coupled pair functional, and averaged quadratic coupled cluster theories.

D-Glucose as a modifying agent in gelatin/collagen matrix and reservoir nanoparticles for Calendula officinalis delivery.

PubMed

Lam, P-L; Kok, S H-L; Bian, Z-X; Lam, K-H; Tang, J C-O; Lee, K K-H; Gambari, R; Chui, C-H

2014-05-01

Gelatin/Collagen-based matrix and reservoir nanoparticles require crosslinkers to stabilize the formed nanosuspensions, considering that physical instability is the main challenge of nanoparticulate systems. The use of crosslinkers improves the physical integrity of nanoformulations under the-host environment. Aldehyde-based fixatives, such as formaldehyde and glutaraldehyde, have been widely applied to the crosslinking process of polymeric nanoparticles. However, their potential toxicity towards human beings has been demonstrated in many previous studies. In order to tackle this problem, D-glucose was used during nanoparticle formation to stabilize the gelatin/collagen-based matrix wall and reservoir wall for the deliveries of Calendula officinalis powder and oil, respectively. In addition, therapeutic selectivity between malignant and normal cells could be observed. The C. officinalis powder loaded nanoparticles significantly strengthened the anti-cancer effect towards human breast adenocarcinoma MCF7 cells and human hepatoma SKHep1 cells when compared with the free powder. On the contrary, the nanoparticles did not show significant cytotoxicity towards normal esophageal epithelial NE3 cells and human skin keratinocyte HaCaT cells. On the basis of these evidences, D-glucose modified gelatin/collagen matrix nanoparticles containing C. officinalis powder might be proposed as a safer alternative vehicle for anti-cancer treatments. Copyright © 2014 Elsevier B.V. All rights reserved.

Marine fouling release silicone/carbon nanotube nanocomposite coatings: on the importance of the nanotube dispersion state.

PubMed

Beigbeder, Alexandre; Mincheva, Rosica; Pettitt, Michala E; Callow, Maureen E; Callow, James A; Claes, Michael; Dubois, Philippe

2010-05-01

The present work reports on the influence of the dispersion quality of multiwall carbon nanotubes (MWCNTs) in a silicone matrix on the marine fouling-release performance of the resulting nanocomposite coatings. A first set of coatings filled with different nanofiller contents was prepared by the dilution of a silicone/MWCNTs masterbatch within a hydrosilylation-curing polydimethylsiloxane resin. The fouling-release properties of the nanocomposite coatings were studied through laboratory assays with the marine alga (seaweed) Ulva, a common fouling species. As reported previously (see Ref. [19]), the addition of a small (0.05%) amount of carbon nanotubes substantially improves the fouling-release properties of the silicone matrix. This paper shows that this improvement is dependent on the amount of filler, with a maximum obtained with 0.1 wt% of multiwall carbon nanotubes (MWCNTs). The method of dispersion of carbon nanotubes in the silicone matrix is also shown to significantly (p = 0.05) influence the fouling-release properties of the coatings. Dispersing 0.1% MWCNTs using the masterbatch approach yielded coatings with circa 40% improved fouling-release properties over those where MWCNTs were dispersed directly in the polymeric matrix. This improvement is directly related to the state of nanofiller dispersion within the cross-linked silicone coating.

4PBA strongly attenuates endoplasmic reticulum stress, fibrosis, and mitochondrial apoptosis markers in cyclosporine treated human gingival fibroblasts.

PubMed

Ranga Rao, Suresh; Subbarayan, Rajasekaran; Ajitkumar, Supraja; Murugan Girija, Dinesh

2018-01-01

Cyclosporine induces overgrowth of human gingiva. Previously we have shown (i) cyclosporine-inducing ER stress in human gingival fibroblasts (HGF), (ii) increased matrix protein expression, and (iii) interference with mitochondrial pro- and anti-apoptotic factors. This study was undertaken to assess the effects of melatonin (an antioxidant), 4PBA (an ER stress inhibitor), and simvastatin on the expression of ER Stress markers as well as on matrix and mitochondrial markers. HGF incubated with cyclosporine, or without melatonin/4PBA/statin. After 24 hr of incubation, mRNA expression of ER stress markers (GRP78, CHOP, XBP1, and XBPs) and matrix protein markers (like α-SMA, VEGF, TGF-β, CTGF), and mitochondrial apoptosis markers estimated and compared with housekeeping gene GAPDH. Compared to the control cyclosporine significantly augmented ER Stress and matrix proteins, which decreased significantly with the use of melatonin, 4PBA, and simvastatin. The mitochondrial proapoptotic molecule cyclophilin D, as well as Bcl2 expression also decreased after PBA treatment, paralleling an increase in cytochrome c expression. The effect of 4PBA was much more pronounced than the influence of other two. In conclusion, 4PBA could be a viable therapeutic option for drug-induced gingival overgrowth. © 2017 Wiley Periodicals, Inc.

Mitochondrial matrix delivery using MITO-Porter, a liposome-based carrier that specifies fusion with mitochondrial membranes

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

Yasuzaki, Yukari; Yamada, Yuma; Harashima, Hideyoshi, E-mail: harasima@pharm.hokudai.ac.jp

2010-06-25

Mitochondria are the principal producers of energy in cells of higher organisms. It was recently reported that mutations and defects in mitochondrial DNA (mtDNA) are associated with various mitochondrial diseases including a variety of neurodegenerative and neuromuscular diseases. Therefore, an effective mitochondrial gene therapy and diagnosis would be expected to have great medical benefits. To achieve this, therapeutic agents need to be delivered into the innermost mitochondrial space (mitochondrial matrix), which contains the mtDNA pool. We previously reported on the development of MITO-Porter, a liposome-based carrier that introduces macromolecular cargos into mitochondria via membrane fusion. In this study, we providemore » a demonstration of mitochondrial matrix delivery and the visualization of mitochondrial genes (mtDNA) in living cells using the MITO-Porter. We first prepared MITO-Porter containing encapsulated propidium iodide (PI), a fluorescent dye used to stain nucleic acids to detect mtDNA. We then confirmed the emission of red-fluorescence from PI by conjugation with mtDNA, when the carriers were incubated in the presence of isolated rat liver mitochondria. Finally, intracellular observation by confocal laser scanning microscopy clearly verified that the MITO-Porter delivered PI to the mitochondrial matrix.« less

Enhanced secretion of TIMP-1 by human hypertrophic scar keratinocytes could contribute to fibrosis.

PubMed

Simon, Franck; Bergeron, Daniele; Larochelle, Sébastien; Lopez-Vallé, Carlos A; Genest, Hervé; Armour, Alexis; Moulin, Véronique J

2012-05-01

Hypertrophic scars are a pathological process characterized by an excessive deposition of extracellular matrix components. Using a tissue-engineered reconstructed human skin (RHS) method, we previously reported that pathological keratinocytes induce formation of a fibrotic dermal matrix. We further investigated keratinocyte action using conditioned media. Results showed that conditioned media induce a similar action on dermal thickness similar to when an epidermis is present. Using a two-dimensional electrophoresis technique, we then compared conditioned media from normal or hypertrophic scar keratinocytes and determined that TIMP-1 was increased in conditioned media from hypertrophic scar keratinocytes. This differential profile was confirmed using ELISA, assaying TIMP-1 presence on media from monolayer cultured keratinocytes and from RHS. The dermal matrix of these RHS was recreated using mesenchymal cells from three different origins (skin, wound and hypertrophic scar). The effect of increased TIMP-1 levels on dermal fibrosis was also validated independently from the mesenchymal cell origin. Immunodetection of TIMP-1 showed that this protein was increased in the epidermis of hypertrophic scar biopsies. The findings of this study represent an important advance in understanding the role of keratinocytes as a direct potent modulator for matrix degradation and scar tissue remodeling, possibly through inactivation of MMPs. Copyright © 2011 Elsevier Ltd and ISBI. All rights reserved.

Simulation of the neutron response matrix of an EJ309 liquid scintillator

NASA Astrophysics Data System (ADS)

Bai, Huaiyong; Wang, Zhimin; Zhang, Luyu; Jiang, Haoyu; Lu, Yi; Chen, Jinxiang; Zhang, Guohui

2018-04-01

The neutron response matrix is the basis for measuring the neutron energy spectrum through unfolding the pulse height spectrum detected with a liquid scintillator. Based on the light output of the EJ309 liquid scintillator and the related reaction cross sections, a Monte Carlo code is developed to obtain the neutron response matrix. The effects of the related reactions, the contributions of different number of neutron interactions and the wall effect of the recoil proton are discussed. With the obtained neutron response matrix and the GRAVEL iterative unfolding method, the neutron energy spectra of the 252Cf and the 241AmBe neutron sources are measured, and the results are respectively compared with the theoretical prediction of the 252Cf neutron energy spectrum and the previous results of the 241AmBe neutron energy spectra.

Degree of coupling and efficiency of energy converters far-from-equilibrium

NASA Astrophysics Data System (ADS)

Vroylandt, Hadrien; Lacoste, David; Verley, Gatien

2018-02-01

In this paper, we introduce a real symmetric and positive semi-definite matrix, which we call the non-equilibrium conductance matrix, and which generalizes the Onsager response matrix for a system in a non-equilibrium stationary state. We then express the thermodynamic efficiency in terms of the coefficients of this matrix using a parametrization similar to the one used near equilibrium. This framework, then valid arbitrarily far from equilibrium allows to set bounds on the thermodynamic efficiency by a universal function depending only on the degree of coupling between input and output currents. It also leads to new general power-efficiency trade-offs valid for macroscopic machines that are compared to trade-offs previously obtained from uncertainty relations. We illustrate our results on an unicycle heat to heat converter and on a discrete model of a molecular motor.

Efficacy of hemostatic matrix and microporous polysaccharide hemospheres.

PubMed

Lewis, Kevin M; Atlee, Holly; Mannone, Angela; Lin, Lawrence; Goppelt, Andreas

2015-02-01

Microporous Polysaccharide Hemospheres (MPH) are a new plant-derived polysaccharide powder hemostat. Previous studies investigated MPH as a replacement to nonflowable hemostatic agents of different application techniques (e.g., oxidized cellulose, collagen); therefore, the purpose of this study was to determine if MPH is a surrogate for flowable hemostatic agents of similar handling and application techniques, specifically a flowable thrombin-gelatin hemostatic matrix. Hemostatic efficacy was compared using a heparinized porcine abrasion model mimicking a capsular tear of a parenchymal organ. MPH (ARISTA, 1 g) and hemostatic matrix (Floseal, 1 mL) were applied, according to a randomized scheme, to paired hepatic abrasions (40 lesions per group). Hemostatic success, control of bleeding, and blood loss were assessed 2, 5, and 10 min after treatment. Hemostatic success and control of bleeding were analyzed using odds ratios and blood loss using mean differences. Hemostatic matrix provided superior hemostatic success relative to MPH at 5 (odds ratio: 0.035, 95% confidence interval: 0.004-0.278) and 10 min (0.032, 0.007-0.150), provided superior control of bleeding at 5 (0.006, <0.001-0.037) and 10 min (0.009, 0.001-0.051), and had significantly less blood loss at 5 (mean difference: 0.3118 mL/min, 95% confidence interval: 0.0939-0.5296) and 10 min (0.5025, 0.2489-0.7561). These findings corroborate other MPH investigations regarding its low-level efficacy and suggest that MPH is not an appropriate surrogate for hemostatic matrix despite similar application techniques. The lack of a procoagulant within MPH may likely be the reason for its lower efficacy and need for multiple applications. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Maintaining Elastogenicity of Mesenchymal Stem Cell-Derived Smooth Muscle Cells in Two-Dimensional Culture.

PubMed

Dahal, Shataakshi; Broekelman, Thomas; Mecham, Robert P; Ramamurthi, Anand

2018-06-01

Abdominal aortic aneurysms (AAAs) are localized expansions of the abdominal aorta that grow slowly to rupture. AAA growth is driven by irreversible elastic matrix breakdown in the aorta wall by chronically upregulated matrix metalloproteases (MMPs). Since adult vascular smooth muscle cells (SMCs) poorly regenerate elastic matrix, we previously explored utility of bone marrow mesenchymal stem cells and SMCs derived therefrom (BM-SMCs) for this purpose. One specific differentiated phenotype (cBM-SMCs) generated on a fibronectin substrate in presence of exogenous transforming growth factor-β and platelet-derived growth factor exhibited superior elastogenicity versus other phenotypes, and usefully provided proelastogenic and antiproteolytic stimuli to aneurysmal SMCs. Since in vivo cell therapy demands large cell inoculates, these derived SMCs must be propagated in vitro while maintaining their superior elastogenic, proelastogenic, and antiproteolytic characteristics. In this work, we thus investigated the culture conditions that must be provided to this propagation phase, which ensure that the differentiated SMCs maintain their phenotype and matrix regenerative benefits. Our results indicate that our BM-SMCs retain their phenotype in long-term culture even in the absence of differentiation growth factors and fibronectin substrate, but these conditions must be continued to be provided during postdifferentiation propagation if they are to maintain their superior elastic matrix deposition, crosslinking, and fiber formation properties. Our study, however, showed that cells propagated under these conditions exhibit higher expression of MMP-2, but favorably, no expression of elastolytic MMP-9. Hence, the study outcomes provide crucial guidelines to maintain phenotypic stability of cBM-SMCs during their propagation in two-dimensional culture before their delivery to the AAA wall for therapy.

A novel chaotic image encryption scheme using DNA sequence operations

NASA Astrophysics Data System (ADS)

Wang, Xing-Yuan; Zhang, Ying-Qian; Bao, Xue-Mei

2015-10-01

In this paper, we propose a novel image encryption scheme based on DNA (Deoxyribonucleic acid) sequence operations and chaotic system. Firstly, we perform bitwise exclusive OR operation on the pixels of the plain image using the pseudorandom sequences produced by the spatiotemporal chaos system, i.e., CML (coupled map lattice). Secondly, a DNA matrix is obtained by encoding the confused image using a kind of DNA encoding rule. Then we generate the new initial conditions of the CML according to this DNA matrix and the previous initial conditions, which can make the encryption result closely depend on every pixel of the plain image. Thirdly, the rows and columns of the DNA matrix are permuted. Then, the permuted DNA matrix is confused once again. At last, after decoding the confused DNA matrix using a kind of DNA decoding rule, we obtain the ciphered image. Experimental results and theoretical analysis show that the scheme is able to resist various attacks, so it has extraordinarily high security.

Dynamic heterogeneities and non-Gaussian behavior in two-dimensional randomly confined colloidal fluids

NASA Astrophysics Data System (ADS)

Schnyder, Simon K.; Skinner, Thomas O. E.; Thorneywork, Alice L.; Aarts, Dirk G. A. L.; Horbach, Jürgen; Dullens, Roel P. A.

2017-03-01

A binary mixture of superparamagnetic colloidal particles is confined between glass plates such that the large particles become fixed and provide a two-dimensional disordered matrix for the still mobile small particles, which form a fluid. By varying fluid and matrix area fractions and tuning the interactions between the superparamagnetic particles via an external magnetic field, different regions of the state diagram are explored. The mobile particles exhibit delocalized dynamics at small matrix area fractions and localized motion at high matrix area fractions, and the localization transition is rounded by the soft interactions [T. O. E. Skinner et al., Phys. Rev. Lett. 111, 128301 (2013), 10.1103/PhysRevLett.111.128301]. Expanding on previous work, we find the dynamics of the tracers to be strongly heterogeneous and show that molecular dynamics simulations of an ideal gas confined in a fixed matrix exhibit similar behavior. The simulations show how these soft interactions make the dynamics more heterogeneous compared to the disordered Lorentz gas and lead to strong non-Gaussian fluctuations.

Randomized placebo controlled blinded study to assess valsartan efficacy in preventing left ventricle remodeling in patients with dual chamber pacemaker--Rationale and design of the trial.

PubMed

Tomasik, Andrzej; Jacheć, Wojciech; Wojciechowska, Celina; Kawecki, Damian; Białkowska, Beata; Romuk, Ewa; Gabrysiak, Artur; Birkner, Ewa; Kalarus, Zbigniew; Nowalany-Kozielska, Ewa

2015-05-01

Dual chamber pacing is known to have detrimental effect on cardiac performance and heart failure occurring eventually is associated with increased mortality. Experimental studies of pacing in dogs have shown contractile dyssynchrony leading to diffuse alterations in extracellular matrix. In parallel, studies on experimental ischemia/reperfusion injury have shown efficacy of valsartan to inhibit activity of matrix metalloproteinase-9, to increase the activity of tissue inhibitor of matrix metalloproteinase-3 and preserve global contractility and left ventricle ejection fraction. To present rationale and design of randomized blinded trial aimed to assess whether 12 month long administration of valsartan will prevent left ventricle remodeling in patients with preserved left ventricle ejection fraction (LVEF ≥ 40%) and first implantation of dual chamber pacemaker. A total of 100 eligible patients will be randomized into three parallel arms: placebo, valsartan 80 mg/daily and valsartan 160 mg/daily added to previously used drugs. The primary endpoint will be assessment of valsartan efficacy to prevent left ventricle remodeling during 12 month follow-up. We assess patients' functional capacity, blood plasma activity of matrix metalloproteinases and their tissue inhibitors, NT-proBNP, tumor necrosis factor alpha, and Troponin T. Left ventricle function and remodeling is assessed echocardiographically: M-mode, B-mode, tissue Doppler imaging. If valsartan proves effective, it will be an attractive measure to improve long term prognosis in aging population and increasing number of pacemaker recipients. ClinicalTrials.org (NCT01805804). Copyright © 2015 Elsevier Inc. All rights reserved.

Scattering Matrix for the Interaction between Solar Acoustic Waves and Sunspots. I. Measurements

NASA Astrophysics Data System (ADS)

Yang, Ming-Hsu; Chou, Dean-Yi; Zhao, Hui

2017-01-01

Assessing the interaction between solar acoustic waves and sunspots is a scattering problem. The scattering matrix elements are the most commonly used measured quantities to describe scattering problems. We use the wavefunctions of scattered waves of NOAAs 11084 and 11092 measured in the previous study to compute the scattering matrix elements, with plane waves as the basis. The measured scattered wavefunction is from the incident wave of radial order n to the wave of another radial order n‧, for n=0{--}5. For a time-independent sunspot, there is no mode mixing between different frequencies. An incident mode is scattered into various modes with different wavenumbers but the same frequency. Working in the frequency domain, we have the individual incident plane-wave mode, which is scattered into various plane-wave modes with the same frequency. This allows us to compute the scattering matrix element between two plane-wave modes for each frequency. Each scattering matrix element is a complex number, representing the transition from the incident mode to another mode. The amplitudes of diagonal elements are larger than those of the off-diagonal elements. The amplitude and phase of the off-diagonal elements are detectable only for n-1≤slant n\\prime ≤slant n+1 and -3{{Δ }}k≤slant δ {k}x≤slant 3{{Δ }}k, where δ {k}x is the change in the transverse component of the wavenumber and Δk = 0.035 rad Mm-1.

Microfabricated discontinuous-edge surface topographies influence osteoblast adhesion, migration, cytoskeletal organization, and proliferation and enhance matrix and mineral deposition in vitro.

PubMed

Hamilton, D W; Wong, K S; Brunette, D M

2006-05-01

The fabrication of surfaces that stimulate increased adhesion, migration, and differentiated function of osteoblasts has been viewed as being desirable for many orthopedic applications. Previous studies have shown that microfabricated pits and grooves alter adhesion, spreading, matrix secretion, and production of mineral by rat calvarial osteoblasts (RCOs). The mechanisms underlying these effects are unknown, although microenvironment and cell alignment are considered to play a role. The aim of this work was to investigate the behavior of RCOs on microfabricated discontinuous-edge surfaces (DESs), which could provide an alternative means to control both the microenvironment and cellular alignment. Two types of discontinuous-type structures were employed, gap-cornered boxes and micron scale pillars. DES gap-cornered boxes and the pillars influenced the arrangement of F-actin, microtubules, and vinculin. Osteoblasts were guided in their direction of migration on both types of substrata. Both box DESs and pillars altered the staining intensity and localization pattern of phosphotyrosine and src-activated FAK localization. Cell multilayering, matrix deposition, and mineralization were enhanced on both discontinuous topographies when compared with smooth controls. This study shows that DESs alter adhesion, migration, and proliferative responses from osteoblasts at early time points (<1 week) and promote multilayering, matrix deposition, and mineral deposition at later times (2-6 weeks). Such topographical patterns could potentially be employed as effective surface features on bone-contacting implants or in membrane-based periodontal applications.

Tensile and compressive behavior of Borsic/aluminum

NASA Technical Reports Server (NTRS)

Herakovich, C. T.; Davis, J. G., Jr.; Viswanathan, C. N.

1977-01-01

The results of an experimental investigation of the mechanical behavior of Borsic/aluminum are presented. Composite laminates were tested in tension and compression for monotonically increasing load and also for variable loading cycles in which the maximum load was increased in each successive cycle. It is shown that significant strain-hardening, and corresponding increase in yield stress, is exhibited by the metal matrix laminates. For matrix dominated laminates, the current yield stress is essentially identical to the previous maximum stress, and unloading is essentially linear with large permanent strains after unloading. For laminates with fiber dominated behavior, the yield stress increases with increase in the previous maximum stress, but the increase in yield stress does not keep pace with the previous maximum stress. These fiber dominated laminates exhibit smaller nonlinear strains, reversed nonlinear behavior during unloading, and smaller permanent strains after unloading. Compression results from sandwich beams and flat coupons are shown to differ considerably. Results from beam specimens tend to exhibit higher values for modulus, yield stress, and strength.

Mechanistic modelling of drug release from a polymer matrix using magnetic resonance microimaging.

PubMed

Kaunisto, Erik; Tajarobi, Farhad; Abrahmsen-Alami, Susanna; Larsson, Anette; Nilsson, Bernt; Axelsson, Anders

2013-03-12

In this paper a new model describing drug release from a polymer matrix tablet is presented. The utilization of the model is described as a two step process where, initially, polymer parameters are obtained from a previously published pure polymer dissolution model. The results are then combined with drug parameters obtained from literature data in the new model to predict solvent and drug concentration profiles and polymer and drug release profiles. The modelling approach was applied to the case of a HPMC matrix highly loaded with mannitol (model drug). The results showed that the drug release rate can be successfully predicted, using the suggested modelling approach. However, the model was not able to accurately predict the polymer release profile, possibly due to the sparse amount of usable pure polymer dissolution data. In addition to the case study, a sensitivity analysis of model parameters relevant to drug release was performed. The analysis revealed important information that can be useful in the drug formulation process. Copyright © 2013 Elsevier B.V. All rights reserved.

Matrix stiffness modulates infection of endothelial cells by Listeria monocytogenes via expression of cell surface vimentin.

PubMed

Bastounis, Effie E; Yeh, Yi-Ting; Theriot, Julie A

2018-05-02

Extracellular matrix stiffness (ECM) is one of the many mechanical forces acting on mammalian adherent cells and an important determinant of cellular function. While the effect of ECM stiffness on many aspects of cellular behavior has been previously studied, how ECM stiffness might mediate susceptibility of host cells to infection by bacterial pathogens was hitherto unexplored. To address this open question, we manufactured hydrogels of varying physiologically-relevant stiffness and seeded human microvascular endothelial cells (HMEC-1) on them. We then infected HMEC-1 with the bacterial pathogen Listeria monocytogenes (Lm), and found that adhesion of Lm onto host cells increases monotonically with increasing matrix stiffness, an effect that requires the activity of focal adhesion kinase (FAK). We identified cell surface vimentin as a candidate surface receptor mediating stiffness-dependent adhesion of Lm to HMEC-1 and found that bacterial infection of these host cells is decreased when the amount of surface vimentin is reduced. Our results provide the first evidence that ECM stiffness can mediate the susceptibility of mammalian host cells to infection by a bacterial pathogen.

Cure Cycle Design Methodology for Fabricating Reactive Resin Matrix Fiber Reinforced Composites: A Protocol for Producing Void-free Quality Laminates

NASA Technical Reports Server (NTRS)

Hou, Tan-Hung

2014-01-01

For the fabrication of resin matrix fiber reinforced composite laminates, a workable cure cycle (i.e., temperature and pressure profiles as a function of processing time) is needed and is critical for achieving void-free laminate consolidation. Design of such a cure cycle is not trivial, especially when dealing with reactive matrix resins. An empirical "trial and error" approach has been used as common practice in the composite industry. Such an approach is not only costly, but also ineffective at establishing the optimal processing conditions for a specific resin/fiber composite system. In this report, a rational "processing science" based approach is established, and a universal cure cycle design protocol is proposed. Following this protocol, a workable and optimal cure cycle can be readily and rationally designed for most reactive resin systems in a cost effective way. This design protocol has been validated through experimental studies of several reactive polyimide composites for a wide spectrum of usage that has been documented in the previous publications.

Expansion and melting of Xe nanocrystals in Si

NASA Astrophysics Data System (ADS)

Faraci, Giuseppe; Pennisi, Agata R.; Zontone, Federico; Li, Boquan; Petrov, Ivan

2006-12-01

Xe agglomerates confined in a Si matrix by ion implantation were synthesized with different size depending on the implantation process and/or the thermal treatment. At low temperature Xe nanocrystals are formed, whose expansion and melting were studied in the range 15- 300K . Previous high resolution x-ray diffraction spectra were corroborated with complementary techniques such as two-dimensional imaging plate patterns and transmission electron microscopy. We detected fcc Xe nanocrystals whose properties were size dependent. The experiments showed that in annealed samples epitaxial condensation of small Xe clusters, on the cavities of the Si matrix, gave in fact expanded and oriented Xe, suggesting a possible preferential growth of Xe(311) planes oriented orthogonally to the Si[02-2] direction. On the contrary, small Xe clusters in an amorphous Si matrix have a fcc lattice contracted as a consequence of surface tension. Furthermore, a solid-to-liquid phase transition size dependent was found. Expansion of fcc Xe lattice was accurately determined as a function of the temperature. Overpressurized nanocrystals and/or binary size distributions were disproved.

In situ characterization of advanced glycation end products (AGEs) in collagen and model extracellular matrix by solid state NMR.

PubMed

Li, R; Rajan, R; Wong, W C V; Reid, D G; Duer, M J; Somovilla, V J; Martinez-Saez, N; Bernardes, G J L; Hayward, R; Shanahan, C M

2017-12-14

Non-enzymatic glycation of extracellular matrix with (U- 13 C 5 )-d-ribose-5-phosphate (R5P), enables in situ 2D ssNMR identification of many deleterious protein modifications and crosslinks, including previously unreported oxalamido and hemiaminal (CH 3 -CH(OH)NHR) substructures. Changes in charged residue proportions and distribution may be as important as crosslinking in provoking and understanding harmful tissue changes.

Minimum-error quantum distinguishability bounds from matrix monotone functions: A comment on 'Two-sided estimates of minimum-error distinguishability of mixed quantum states via generalized Holevo-Curlander bounds' [J. Math. Phys. 50, 032106 (2009)

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

Tyson, Jon

2009-06-15

Matrix monotonicity is used to obtain upper bounds on minimum-error distinguishability of arbitrary ensembles of mixed quantum states. This generalizes one direction of a two-sided bound recently obtained by the author [J. Tyson, J. Math. Phys. 50, 032106 (2009)]. It is shown that the previously obtained special case has unique properties.

Robust alignment of chromatograms by statistically analyzing the shifts matrix generated by moving window fast Fourier transform cross-correlation.

PubMed

Zhang, Mingjing; Wen, Ming; Zhang, Zhi-Min; Lu, Hongmei; Liang, Yizeng; Zhan, Dejian

2015-03-01

Retention time shift is one of the most challenging problems during the preprocessing of massive chromatographic datasets. Here, an improved version of the moving window fast Fourier transform cross-correlation algorithm is presented to perform nonlinear and robust alignment of chromatograms by analyzing the shifts matrix generated by moving window procedure. The shifts matrix in retention time can be estimated by fast Fourier transform cross-correlation with a moving window procedure. The refined shift of each scan point can be obtained by calculating the mode of corresponding column of the shifts matrix. This version is simple, but more effective and robust than the previously published moving window fast Fourier transform cross-correlation method. It can handle nonlinear retention time shift robustly if proper window size has been selected. The window size is the only one parameter needed to adjust and optimize. The properties of the proposed method are investigated by comparison with the previous moving window fast Fourier transform cross-correlation and recursive alignment by fast Fourier transform using chromatographic datasets. The pattern recognition results of a gas chromatography mass spectrometry dataset of metabolic syndrome can be improved significantly after preprocessing by this method. Furthermore, the proposed method is available as an open source package at https://github.com/zmzhang/MWFFT2. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Simultaneous separation and quantitation of amino acids and polyamines of forest tree tissues and cell cultures within a single high-performance liquid chromatography run using dansyl derivatization

Treesearch

Rakesh Minocha; Stephanie Long

2004-01-01

The objective of the present study was to develop a rapid HPLC method for simultaneous separation and quantitation of dansylated amino acids and common polyamines in the same matrix for analyzing forest tree tissues and cell cultures. The major modifications incorporated into this method as compared to previously published HPLC methods for separation of only dansyl...

Attributed community mining using joint general non-negative matrix factorization with graph Laplacian

NASA Astrophysics Data System (ADS)

Chen, Zigang; Li, Lixiang; Peng, Haipeng; Liu, Yuhong; Yang, Yixian

2018-04-01

Community mining for complex social networks with link and attribute information plays an important role according to different application needs. In this paper, based on our proposed general non-negative matrix factorization (GNMF) algorithm without dimension matching constraints in our previous work, we propose the joint GNMF with graph Laplacian (LJGNMF) to implement community mining of complex social networks with link and attribute information according to different application needs. Theoretical derivation result shows that the proposed LJGNMF is fully compatible with previous methods of integrating traditional NMF and symmetric NMF. In addition, experimental results show that the proposed LJGNMF can meet the needs of different community minings by adjusting its parameters, and the effect is better than traditional NMF in the community vertices attributes entropy.

A new construction of Calabi-Yau manifolds: Generalized CICYs

NASA Astrophysics Data System (ADS)

Anderson, Lara B.; Apruzzi, Fabio; Gao, Xin; Gray, James; Lee, Seung-Joo

2016-05-01

We present a generalization of the complete intersection in products of projective space (CICY) construction of Calabi-Yau manifolds. CICY three-folds and four-folds have been studied extensively in the physics literature. Their utility stems from the fact that they can be simply described in terms of a 'configuration matrix', a matrix of integers from which many of the details of the geometries can be easily extracted. The generalization we present is to allow negative integers in the configuration matrices which were previously taken to have positive semi-definite entries. This broadening of the complete intersection construction leads to a larger class of Calabi-Yau manifolds than that considered in previous work, which nevertheless enjoys much of the same degree of calculational control. These new Calabi-Yau manifolds are complete intersections in (not necessarily Fano) ambient spaces with an effective anticanonical class. We find examples with topology distinct from any that has appeared in the literature to date. The new manifolds thus obtained have many interesting features. For example, they can have smaller Hodge numbers than ordinary CICYs and lead to many examples with elliptic and K3-fibration structures relevant to F-theory and string dualities.

Modular structural elements in the replication origin region of Tetrahymena rDNA.

PubMed Central

Du, C; Sanzgiri, R P; Shaiu, W L; Choi, J K; Hou, Z; Benbow, R M; Dobbs, D L

1995-01-01

Computer analyses of the DNA replication origin region in the amplified rRNA genes of Tetrahymena thermophila identified a potential initiation zone in the 5'NTS [Dobbs, Shaiu and Benbow (1994), Nucleic Acids Res. 22, 2479-2489]. This region consists of a putative DNA unwinding element (DUE) aligned with predicted bent DNA segments, nuclear matrix or scaffold associated region (MAR/SAR) consensus sequences, and other common modular sequence elements previously shown to be clustered in eukaryotic chromosomal origin regions. In this study, two mung bean nuclease-hypersensitive sites in super-coiled plasmid DNA were localized within the major DUE-like element predicted by thermodynamic analyses. Three restriction fragments of the 5'NTS region predicted to contain bent DNA segments exhibited anomalous migration characteristic of bent DNA during electrophoresis on polyacrylamide gels. Restriction fragments containing the 5'NTS region bound Tetrahymena nuclear matrices in an in vitro binding assay, consistent with an association of the replication origin region with the nuclear matrix in vivo. The direct demonstration in a protozoan origin region of elements previously identified in Drosophila, chick and mammalian origin regions suggests that clusters of modular structural elements may be a conserved feature of eukaryotic chromosomal origins of replication. Images PMID:7784181

Unexpected timely fracture union in matrix metalloproteinase 9 deficient mice.

PubMed

Yuasa, Masato; Saito, Masanori; Molina, Cesar; Moore-Lotridge, Stephanie N; Benvenuti, Michael A; Mignemi, Nicholas A; Okawa, Atsushi; Yoshii, Toshitaka; Schwartz, Herbert S; Nyman, Jeffry S; Schoenecker, Jonathan G

2018-01-01

Immediately following a fracture, a fibrin laden hematoma is formed to prevent bleeding and infection. Subsequently, the organized removal of fibrin, via the protease plasmin, is essential to permit fracture repair through angiogenesis and ossification. Yet, when plasmin activity is lost, the depletion of fibrin alone is insufficient to fully restore fracture repair, suggesting the existence of additional plasmin targets important for fracture repair. Previously, activated matrix metalloproteinase 9 (MMP-9) was demonstrated to function in fracture repair by promoting angiogenesis. Given that MMP-9 is a defined plasmin target, it was hypothesized that pro-MMP-9, following plasmin activation, promotes fracture repair. This hypothesis was tested in a fixed murine femur fracture model with serial assessment of fracture healing. Contrary to previous findings, a complete loss of MMP-9 failed to affect fracture healing and union through 28 days post injury. Therefore, these results demonstrated that MMP-9 is dispensable for timely fracture union and cartilage transition to bone in fixed femur fractures. Pro-MMP-9 is therefore not a significant target of plasmin in fracture repair and future studies assessing additional plasmin targets associated with angiogenesis are warranted.

Direct S -matrix calculation for diffractive structures and metasurfaces

NASA Astrophysics Data System (ADS)

Shcherbakov, Alexey A.; Stebunov, Yury V.; Baidin, Denis F.; Kämpfe, Thomas; Jourlin, Yves

2018-06-01

The paper presents a derivation of analytical components of S matrices for arbitrary planar diffractive structures and metasurfaces in the Fourier domain. The attained general formulas for S -matrix components can be applied within both formulations in the Cartesian and curvilinear metric. A numerical method based on these results can benefit from all previous improvements of the Fourier domain methods. In addition, we provide expressions for S -matrix calculation in the case of periodically corrugated layers of two-dimensional materials, which are valid for arbitrary corrugation depth-to-period ratios. As an example, the derived equations are used to simulate resonant grating excitation of graphene plasmons and the impact of a silica interlayer on corresponding reflection curves.

On Max-Plus Algebra and Its Application on Image Steganography

PubMed Central

Santoso, Kiswara Agung

2018-01-01

We propose a new steganography method to hide an image into another image using matrix multiplication operations on max-plus algebra. This is especially interesting because the matrix used in encoding or information disguises generally has an inverse, whereas matrix multiplication operations in max-plus algebra do not have an inverse. The advantages of this method are the size of the image that can be hidden into the cover image, larger than the previous method. The proposed method has been tested on many secret images, and the results are satisfactory which have a high level of strength and a high level of security and can be used in various operating systems. PMID:29887761

Effects of sources on time-domain finite difference models.

PubMed

Botts, Jonathan; Savioja, Lauri

2014-07-01

Recent work on excitation mechanisms in acoustic finite difference models focuses primarily on physical interpretations of observed phenomena. This paper offers an alternative view by examining the properties of models from the perspectives of linear algebra and signal processing. Interpretation of a simulation as matrix exponentiation clarifies the separate roles of sources as boundaries and signals. Boundary conditions modify the matrix and thus its modal structure, and initial conditions or source signals shape the solution, but not the modal structure. Low-frequency artifacts are shown to follow from eigenvalues and eigenvectors of the matrix, and previously reported artifacts are predicted from eigenvalue estimates. The role of source signals is also briefly discussed.

On Max-Plus Algebra and Its Application on Image Steganography.

PubMed

Santoso, Kiswara Agung; Fatmawati; Suprajitno, Herry

2018-01-01

We propose a new steganography method to hide an image into another image using matrix multiplication operations on max-plus algebra. This is especially interesting because the matrix used in encoding or information disguises generally has an inverse, whereas matrix multiplication operations in max-plus algebra do not have an inverse. The advantages of this method are the size of the image that can be hidden into the cover image, larger than the previous method. The proposed method has been tested on many secret images, and the results are satisfactory which have a high level of strength and a high level of security and can be used in various operating systems.

The photobase generator nifedipine as a novel matrix for the detection of polyphenols in matrix-assisted laser desorption/ionization mass spectrometry.

PubMed

Nguyen, Huu-Nghi; Tanaka, Mitsuru; Komabayashi, Genki; Matsui, Toshiro

2016-10-01

Matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS) is widely used for the detection and analysis of ionizable compounds. However, the method has less potential for the analysis of neutral compounds, such as polyphenols, owing to their lack of favorable proton-attachment or -removal groups. In this study, we reported for the first time that nifedipine (2,6-dimethyl-3,5-dicarbomethoxy-4-(2-nitrophenyl)-1,4-dihydropyridine), which is a strong photobase generator commonly used in polymerization, can abstract protons from neutral compounds in negative mode-MALDI experiments. When nifedipine (5 mg/ml) was used as a matrix reagent, the limit of detection (LOD) for epigallocatechin-3-O-gallate (EGCG) was determined to be 100 fmol/spot, which constitutes >50-fold improvement compared to the LOD obtained when trans-3-indoleacrylic acid, a matrix reagent previously reported for polyphenol detection, was used. Of the dihydropyridines investigated, only nifedipine facilitated the detection of EGCG, suggesting that the nitrosophenyl pyridine derivative of nifedipine formed by photoreduction under laser irradiation at 355 nm plays a crucial role in detecting polyphenols in negative mode. Reduced MS detection of 5-O-methylnaringenin indicated that nifedipine may preferably remove a proton from the 5-position OH group in the A ring of the flavonoid skeleton. The significant MS detection by nifedipine was extensively observed for polyphenols including flavones, flavonones, chalcones, stilbenoids and phenolic acids. In conclusion, nifedipine can act as a novel matrix for improving polyphenol detection by MALDI-MS in negative mode. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Electronic coupling matrix elements from charge constrained density functional theory calculations using a plane wave basis set

NASA Astrophysics Data System (ADS)

Oberhofer, Harald; Blumberger, Jochen

2010-12-01

We present a plane wave basis set implementation for the calculation of electronic coupling matrix elements of electron transfer reactions within the framework of constrained density functional theory (CDFT). Following the work of Wu and Van Voorhis [J. Chem. Phys. 125, 164105 (2006)], the diabatic wavefunctions are approximated by the Kohn-Sham determinants obtained from CDFT calculations, and the coupling matrix element calculated by an efficient integration scheme. Our results for intermolecular electron transfer in small systems agree very well with high-level ab initio calculations based on generalized Mulliken-Hush theory, and with previous local basis set CDFT calculations. The effect of thermal fluctuations on the coupling matrix element is demonstrated for intramolecular electron transfer in the tetrathiafulvalene-diquinone (Q-TTF-Q-) anion. Sampling the electronic coupling along density functional based molecular dynamics trajectories, we find that thermal fluctuations, in particular the slow bending motion of the molecule, can lead to changes in the instantaneous electron transfer rate by more than an order of magnitude. The thermal average, ( {< {| {H_ab } |^2 } > } )^{1/2} = 6.7 {mH}, is significantly higher than the value obtained for the minimum energy structure, | {H_ab } | = 3.8 {mH}. While CDFT in combination with generalized gradient approximation (GGA) functionals describes the intermolecular electron transfer in the studied systems well, exact exchange is required for Q-TTF-Q- in order to obtain coupling matrix elements in agreement with experiment (3.9 mH). The implementation presented opens up the possibility to compute electronic coupling matrix elements for extended systems where donor, acceptor, and the environment are treated at the quantum mechanical (QM) level.

Dark matter statistics for large galaxy catalogs: power spectra and covariance matrices

NASA Astrophysics Data System (ADS)

Klypin, Anatoly; Prada, Francisco

2018-06-01

Large-scale surveys of galaxies require accurate theoretical predictions of the dark matter clustering for thousands of mock galaxy catalogs. We demonstrate that this goal can be achieve with the new Parallel Particle-Mesh (PM) N-body code GLAM at a very low computational cost. We run ˜22, 000 simulations with ˜2 billion particles that provide ˜1% accuracy of the dark matter power spectra P(k) for wave-numbers up to k ˜ 1hMpc-1. Using this large data-set we study the power spectrum covariance matrix. In contrast to many previous analytical and numerical results, we find that the covariance matrix normalised to the power spectrum C(k, k΄)/P(k)P(k΄) has a complex structure of non-diagonal components: an upturn at small k, followed by a minimum at k ≈ 0.1 - 0.2 hMpc-1, and a maximum at k ≈ 0.5 - 0.6 hMpc-1. The normalised covariance matrix strongly evolves with redshift: C(k, k΄)∝δα(t)P(k)P(k΄), where δ is the linear growth factor and α ≈ 1 - 1.25, which indicates that the covariance matrix depends on cosmological parameters. We also show that waves longer than 1h-1Gpc have very little impact on the power spectrum and covariance matrix. This significantly reduces the computational costs and complexity of theoretical predictions: relatively small volume ˜(1h-1Gpc)3 simulations capture the necessary properties of dark matter clustering statistics. As our results also indicate, achieving ˜1% errors in the covariance matrix for k < 0.50 hMpc-1 requires a resolution better than ɛ ˜ 0.5h-1Mpc.

Grape seed extracts inhibit dentin matrix degradation by MMP-3

PubMed Central

Khaddam, Mayssam; Salmon, Benjamin; Le Denmat, Dominique; Tjaderhane, Leo; Menashi, Suzanne; Chaussain, Catherine; Rochefort, Gaël Y.; Boukpessi, Tchilalo

2014-01-01

Since Matrix metalloproteinases (MMPs) have been suggested to contribute to dentin caries progression, the hypothesis that MMP inhibition would affect the progression of dentin caries is clinically relevant. Grape seed extracts (GSE) have been previously reported to be natural inhibitors of MMPs. Objective: To evaluate the capacity of a GSE mouthrinse to prevent the degradation of demineralized dentin matrix by MMP-3 (stromelysin-1). Materials and Methods: Standardized blocks of dentin obtained from sound permanent teeth extracted for orthodontic reasons were demineralized with Ethylenediaminetetraacetic acid (EDTA) and pretreated either with (A) GSE (0.2% w/v), (B) amine fluoride (AmF) (20% w/v), (C) a mouthrinse which contains both, (D) placebo, (E) sodium fluoride (0.15 mg.ml−1), (F) PBS, (G) Chlorhexidine digluconate (CHX), or (H) zinc chloride (ZnCl2). The dentin blocks were then incubated with activated recombinant MMP-3. The supernatants were analyzed by Western Blot for several dentin matrix proteins known to be MMP-3 substrate. In parallel, scanning electron microscopy (SEM) was performed on resin replica of the dentin blocks. Results: Western blot analysis of the supernatants revealed that MMP-3 released from the dentin matrix small proteoglycans (decorin and biglycan) and dentin sialoprotein (DSP) in the AmF, sodium fluoride, PBS and placebo pretreated groups, but not in the GSE and mouthrinse pretreated groups. SEM examination of resin replica showed that the mouthrinse and its active components not only had an anti-MMP action but also modified the dentin surface accessibility. Conclusion: This study shows that GSE either alone or combined with AmF as in the evaluated mouthrinse limits dentin matrix degradation. This association may be promising to prevent the progression of caries within dentin. However, the procedure should be adapted to clinically relevant durations. PMID:25400590

Tectonic slicing and mixing processes along the subduction interface: The Sistan example (Eastern Iran)

NASA Astrophysics Data System (ADS)

Bonnet, G.; Agard, P.; Angiboust, S.; Monié, P.; Jentzer, M.; Omrani, J.; Whitechurch, H.; Fournier, M.

2018-06-01

Suture zones preserve metamorphosed relicts of subducted ocean floor later exhumed along the plate interface that can provide critical insights on subduction zone processes. Mélange-like units are exceptionally well-exposed in the Sistan suture (Eastern Iran), which results from the closure of a branch of the Neotethys between the Lut and Afghan continental blocks. High pressure rocks found in the inner part of the suture zone (i.e., Ratuk complex) around Gazik are herein compared to previously studied outcrops along the belt. Detailed field investigations and mapping allow the distinction of two kinds of subduction-related block-in-matrix units: a siliciclastic-matrix complex and a serpentinite-matrix complex. The siliciclastic-matrix complex includes barely metamorphosed blocks of serpentinized peridotite, radiolarite and basalt of maximum greenschist-facies grade (i.e., maximum temperature of 340 °C). The serpentinite-matrix complex includes blocks of various grades and lithologies: mafic eclogites, amphibolitized blueschists, blue-amphibole-bearing metacherts and aegirine-augite-albite rocks. Eclogites reached peak pressure conditions around 530 °C and 2.3 GPa and isothermal retrogression down to 530 °C and 0.9 GPa. Estimation of peak PT conditions for the other rocks are less-well constrained but suggest equilibration at P < 1 GPa. Strikingly similar Ar-Ar ages of 86 ± 3 Ma, along 70 km, are obtained for phengite and amphibole from fourteen eclogite and amphibolitized blueschist blocks. Ages in Gazik are usually younger than further south (e.g., Sulabest), but there is little age difference between the various kinds of rocks. These results (radiometric ages, observed structures and rock types) support a tectonic origin of the serpentinite-matrix mélange and shed light on subduction zone dynamics, particularly on coeval detachment and exhumation mechanisms of slab-derived rocks.

Geochemical and oxygen isotope perspective of a new R chondrite Dhofar 1671: Affinity with ordinary chondrites

NASA Astrophysics Data System (ADS)

Ali, Arshad; Nasir, Sobhi J.; Jabeen, Iffat; Al Rawas, Ahmed; Banerjee, Neil R.; Osinski, Gordon R.

2017-09-01

Dhofar 1671 is a relatively new meteorite that previous studies suggest belongs to the Rumuruti chondrite class. Major and REE compositions are generally in agreement with average values of the R chondrites (RCs). Moderately volatile elements such as Se and Zn abundances are lower than the R chondrite values that are similar to those in ordinary chondrites (OCs). Porphyritic olivine pyroxene (POP), radial pyroxene (RP), and barred olivine (BO) chondrules are embedded in a proportionately equal volume of matrix, one of the characteristic features of RCs. Microprobe analyses demonstrate compositional zoning in chondrule and matrix olivines showing Fa-poor interior and Fa-rich outer zones. Precise oxygen isotope data for chondrules and matrix obtained by laser-assisted fluorination show a genetic isotopic relationship between OCs and RCs. On the basis of our data, we propose a strong affinity between these groups and suggest that OC chondrule precursors could have interacted with a 17O-rich matrix to form RC chondrules (i.e., ∆17O shifts from 1‰ to 3‰). These interactions could have occurred at the same time as "exotic" clasts in brecciated samples formed such as NWA 10214 (LL3-6), Parnallee (LL3), PCA91241 (R3.8-6), and Dhofar 1671 (R3.6). We also infer that the source of the oxidation and 17O enrichment is the matrix, which may have been enriched in 17O-rich water. The abundance of matrix in RCs relative to OCs, ensured that these rocks would be apparently more oxidized and appreciably 17O-enriched. In situ analysis of Dhofar 1671 is recommended to further strengthen the link between OCs and RCs.

Degradomic and yeast 2-hybrid inactive catalytic domain substrate trapping identifies new membrane-type 1 matrix metalloproteinase (MMP14) substrates: CCN3 (Nov) and CCN5 (WISP2).

PubMed

Butler, Georgina S; Connor, Andrea R; Sounni, Nor Eddine; Eckhard, Ulrich; Morrison, Charlotte J; Noël, Agnès; Overall, Christopher M

2017-05-01

Members of the CCN family of matricellular proteins are cytokines linking cells to the extracellular matrix. We report that CCN3 (Nov) and CCN5 (WISP2) are novel substrates of MMP14 (membrane-type 1-matrix metalloproteinase, MT1-MMP) that we identified using MMP14 "inactive catalytic domain capture" (ICDC) as a yeast two-hybrid protease substrate trapping platform in parallel with degradomics mass spectrometry screens for MMP14 substrates. CCN3 and CCN5, previously unknown substrates of MMPs, were biochemically validated as substrates of MMP14 and other MMPs in vitro-CCN5 was processed in the variable region by MMP14 and MMP2, as well as by MMP1, 3, 7, 8, 9 and 15. CCN1, 2 and 3 are proangiogenic factors yet we found novel opposing activity of CCN5 that was potently antiangiogenic in an aortic ring vessel outgrowth model. MMP14, a known regulator of angiogenesis, cleaved CCN5 and abrogated the angiostatic activity. CCN3 was also processed in the variable region by MMP14 and MMP2, and by MMP1, 8 and 9. In addition to the previously reported cleavages of CCN1 and CCN2 by several MMPs we found that MMPs 8, 9, and 1 process CCN1, and MMP8 and MMP9 also process CCN2. Thus, our study reveals additional and pervasive family-wide processing of CCN matricellular proteins/cytokines by MMPs. Furthermore, CCN5 cleavage by proangiogenic MMPs results in removal of an angiogenic brake held by CCN5. This highlights the importance of thorough dissection of MMP substrates that is needed to reveal higher-level control mechanisms beyond type IV collagen and other extracellular matrix protein remodelling in angiogenesis. We find CCN family member cleavage by MMPs is more pervasive than previously reported and includes CCN3 (Nov) and CCN5 (WISP2). CCN5 is a novel antiangiogenic factor, whose function is abrogated by proangiogenic MMP cleavage. By processing CCN proteins, MMPs regulate cell responses angiogenesis in connective tissues. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Fiber Contraction Approaches for Improving CMC Proportional Limit

NASA Technical Reports Server (NTRS)

DiCarlo, James A.; Yun, Hee Mann

1997-01-01

The fact that the service life of ceramic matrix composites (CMC) decreases dramatically for stresses above the CMC proportional limit has triggered a variety of research activities to develop microstructural approaches that can significantly improve this limit. As discussed in a previous report, both local and global approaches exist for hindering the propagation of cracks through the CMC matrix, the physical source for the proportional limit. Local approaches include: (1) minimizing fiber diameter and matrix modulus; (2) maximizing fiber volume fraction, fiber modulus, and matrix toughness; and (3) optimizing fiber-matrix interfacial shear strength; all of which should reduce the stress concentration at the tip of cracks pre existing or created in the matrix during CMC service. Global approaches, as with pre-stressed concrete, center on seeking mechanisms for utilizing the reinforcing fiber to subject the matrix to in-situ compressive stresses which will remain stable during CMC service. Demonstrated CMC examples for the viability of this residual stress approach are based on strain mismatches between the fiber and matrix in their free states, such as, thermal expansion mismatch and creep mismatch. However, these particular mismatch approaches are application limited in that the residual stresses from expansion mismatch are optimum only at low CMC service temperatures and the residual stresses from creep mismatch are typically unidirectional and difficult to implement in complex-shaped CMC.

Silencing by nuclear matrix attachment distinguishes cell-type specificity: association with increased proliferation capacity

PubMed Central

Linnemann, Amelia K.; Krawetz, Stephen A.

2009-01-01

DNA loop organization by nuclear scaffold/matrix attachment is a key regulator of gene expression that may provide a means to modulate phenotype. We have previously shown that attachment of genes to the NaCl-isolated nuclear matrix correlates with their silencing in HeLa cells. In contrast, expressed genes were associated with the lithium 3,5-diiodosalicylate (LIS)-isolated nuclear scaffold. To define their role in determining phenotype matrix attached regions (MARs) on human chromosomes 14–18 were identified as a function of expression in a primary cell line. The locations of MARs in aortic adventitial fibroblast (AoAF) cells were very stable (r = 0.909) and 96% of genes attached at MARs are silent (P < 0.001). Approximately one-third of the genes uniquely expressed in AoAF cells were associated with the HeLa cell nuclear matrix and silenced. Comparatively, 81% were associated with the AoAF cell nuclear scaffold (P < 0.001) and expressed. This suggests that nuclear scaffold/matrix association mediates a portion of cell type-specific gene expression thereby modulating phenotype. Interestingly, nuclear matrix attachment and thus silencing of specific genes that regulate proliferation and maintain the integrity of the HeLa cell genome suggests that transformation may at least in part be achieved through aberrant nuclear matrix attachment. PMID:19276204

Near-optimal matrix recovery from random linear measurements.

PubMed

Romanov, Elad; Gavish, Matan

2018-06-25

In matrix recovery from random linear measurements, one is interested in recovering an unknown M-by-N matrix [Formula: see text] from [Formula: see text] measurements [Formula: see text], where each [Formula: see text] is an M-by-N measurement matrix with i.i.d. random entries, [Formula: see text] We present a matrix recovery algorithm, based on approximate message passing, which iteratively applies an optimal singular-value shrinker-a nonconvex nonlinearity tailored specifically for matrix estimation. Our algorithm typically converges exponentially fast, offering a significant speedup over previously suggested matrix recovery algorithms, such as iterative solvers for nuclear norm minimization (NNM). It is well known that there is a recovery tradeoff between the information content of the object [Formula: see text] to be recovered (specifically, its matrix rank r) and the number of linear measurements n from which recovery is to be attempted. The precise tradeoff between r and n, beyond which recovery by a given algorithm becomes possible, traces the so-called phase transition curve of that algorithm in the [Formula: see text] plane. The phase transition curve of our algorithm is noticeably better than that of NNM. Interestingly, it is close to the information-theoretic lower bound for the minimal number of measurements needed for matrix recovery, making it not only state of the art in terms of convergence rate, but also near optimal in terms of the matrices it successfully recovers. Copyright © 2018 the Author(s). Published by PNAS.

A chimeric protein composed of NuMA fused to the DNA binding domain of LANA is sufficient for the ori-P-dependent DNA replication

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

Ohsaki, Eriko; Ueda, Keiji, E-mail: kueda@virus.me

The Kaposi's sarcoma-associated herpesvirus (KSHV) genome is stably maintained in KSHV-infected PEL cell lines during cell division. We previously showed that accumulation of LANA in the nuclear matrix fraction could be important for the latent DNA replication, and that the functional significance of LANA should be its recruitment of ori-P to the nuclear matrix. Here, we investigated whether the forced localization of the LANA-DNA binding domain (DBD) to the nuclear matrix facilitated ori-P-containing plasmid replication. We demonstrated that chimeric proteins constructed by fusion of LANA DBD with the nuclear mitotic apparatus protein (NuMA), which is one of the components ofmore » the nuclear matrix, could bind with ori-P and enhance replication of an ori-P-containing plasmid, compared with that in the presence of DBD alone. These results further suggested that the ori-P recruitment to the nuclear matrix through the binding with DBD is important for latent viral DNA replication. - Highlights: •KSHV replication in latency depends on LANA localization to the nuclear matrix. •LANA DBD was fused with NuMA, a nuclear matrix protein, at the N- and C-terminus. •NuMA-DBD was in the nuclear matrix and supported the ori-P dependent replication. •LANA in the nuclear matrix should be important for the KSHV replication in latency.« less

Two band model for the cuprates

NASA Astrophysics Data System (ADS)

Liu, Shiu; White, Steven

2009-03-01

We use a numerical canonical transformation approach to derive an effective two-band model for the hole-doped cuprates, which keeps both oxygen and copper orbitals but removes double occupancy from each. A similar model was considered previously by Frenkel, Gooding, Shraiman, and Siggia (PRB 41, number 1, page 350). We compare the numerically derived model with previously obtained analytical results. In addition to the usual hopping terms between oxygens tpp and Cu-Cu exchange terms Jdd, the model also includes a strong copper-oxygen exchange interaction Jpd and a Kondo-like spin-flip oxygen-oxygen hopping term Kpdp. We use the density matrix renormalization group to study the charge, spin, and pairing properties of the derived model on ladder systems.

Local matrix learning in clustering and applications for manifold visualization.

PubMed

Arnonkijpanich, Banchar; Hasenfuss, Alexander; Hammer, Barbara

2010-05-01

Electronic data sets are increasing rapidly with respect to both, size of the data sets and data resolution, i.e. dimensionality, such that adequate data inspection and data visualization have become central issues of data mining. In this article, we present an extension of classical clustering schemes by local matrix adaptation, which allows a better representation of data by means of clusters with an arbitrary spherical shape. Unlike previous proposals, the method is derived from a global cost function. The focus of this article is to demonstrate the applicability of this matrix clustering scheme to low-dimensional data embedding for data inspection. The proposed method is based on matrix learning for neural gas and manifold charting. This provides an explicit mapping of a given high-dimensional data space to low dimensionality. We demonstrate the usefulness of this method for data inspection and manifold visualization. 2009 Elsevier Ltd. All rights reserved.

Statistical analysis of effective singular values in matrix rank determination

NASA Technical Reports Server (NTRS)

Konstantinides, Konstantinos; Yao, Kung

1988-01-01

A major problem in using SVD (singular-value decomposition) as a tool in determining the effective rank of a perturbed matrix is that of distinguishing between significantly small and significantly large singular values to the end, conference regions are derived for the perturbed singular values of matrices with noisy observation data. The analysis is based on the theories of perturbations of singular values and statistical significance test. Threshold bounds for perturbation due to finite-precision and i.i.d. random models are evaluated. In random models, the threshold bounds depend on the dimension of the matrix, the noisy variance, and predefined statistical level of significance. Results applied to the problem of determining the effective order of a linear autoregressive system from the approximate rank of a sample autocorrelation matrix are considered. Various numerical examples illustrating the usefulness of these bounds and comparisons to other previously known approaches are given.

Acellular dermal matrix as an adjunct in treatment of neuropathic pain at the wrist.

PubMed

Peterson, Steven L; Adham, Mehdi N

2006-08-01

Traumatic or surgical injury to superficial sensory nerves at the wrist can lead to significant morbidity. Multiple treatment modalities have been proposed, including the use of flap coverage to provide soft-tissue padding and decrease tactile irritation. In this report, acellular dermal matrix (AlloDerm) was used as an alternative to flap coverage, thereby avoiding the need for a donor site. Five patients with postsurgical and five patients with posttraumatic neuropathic pain at the wrist underwent neuroma excision and/or neurolysis followed by interposition of acellular dermal matrix allograft between skin and nerve. Patients were followed from 12 to 25 months and demonstrated substantial improvement in pain. Eight previously employed patients returned to their prior occupations. Dermal matrix allograft may provide cushioning and/or a gliding surface for the nerve and represents a simple alternative to flap coverage in the treatment of neuropathic pain at the wrist.

Fine-granularity inference and estimations to network traffic for SDN.

PubMed

Jiang, Dingde; Huo, Liuwei; Li, Ya

2018-01-01

An end-to-end network traffic matrix is significantly helpful for network management and for Software Defined Networks (SDN). However, the end-to-end network traffic matrix's inferences and estimations are a challenging problem. Moreover, attaining the traffic matrix in high-speed networks for SDN is a prohibitive challenge. This paper investigates how to estimate and recover the end-to-end network traffic matrix in fine time granularity from the sampled traffic traces, which is a hard inverse problem. Different from previous methods, the fractal interpolation is used to reconstruct the finer-granularity network traffic. Then, the cubic spline interpolation method is used to obtain the smooth reconstruction values. To attain an accurate the end-to-end network traffic in fine time granularity, we perform a weighted-geometric-average process for two interpolation results that are obtained. The simulation results show that our approaches are feasible and effective.

High temperature tension-compression fatigue behavior of a tungsten copper composite

NASA Technical Reports Server (NTRS)

Verrilli, Michael J.; Gabb, Timothy P.

1990-01-01

The high temperature fatigue of a (O)12 tungsten fiber reinforced copper matrix composite was investigated. Specimens having fiber volume percentages of 10 and 36 were fatigued under fully-reversed, strain-controlled conditions at both 260 and 560 C. The fatigue life was found to be independent of fiber volume fraction because fatigue damage preferentially occurred in the matrix. Also, the composite fatigue lives were shorter at 560 C as compared to 260 C due to changes in mode of matrix failure. On a total strain basis, the fatigue life of the composite at 560 C was the same as the life of unreinforced copper, indicating that the presence of the fibers did not degrade the fatigue resistance of the copper matrix in this composite system. Comparison of strain-controlled fatigue data to previously-generated load-controlled data revealed that the strain-controlled fatigue lives were longer because of mean strain and mean stress effects.

Fine-granularity inference and estimations to network traffic for SDN

PubMed Central

Huo, Liuwei; Li, Ya

2018-01-01

An end-to-end network traffic matrix is significantly helpful for network management and for Software Defined Networks (SDN). However, the end-to-end network traffic matrix's inferences and estimations are a challenging problem. Moreover, attaining the traffic matrix in high-speed networks for SDN is a prohibitive challenge. This paper investigates how to estimate and recover the end-to-end network traffic matrix in fine time granularity from the sampled traffic traces, which is a hard inverse problem. Different from previous methods, the fractal interpolation is used to reconstruct the finer-granularity network traffic. Then, the cubic spline interpolation method is used to obtain the smooth reconstruction values. To attain an accurate the end-to-end network traffic in fine time granularity, we perform a weighted-geometric-average process for two interpolation results that are obtained. The simulation results show that our approaches are feasible and effective. PMID:29718913

Non-convex Statistical Optimization for Sparse Tensor Graphical Model

PubMed Central

Sun, Wei; Wang, Zhaoran; Liu, Han; Cheng, Guang

2016-01-01

We consider the estimation of sparse graphical models that characterize the dependency structure of high-dimensional tensor-valued data. To facilitate the estimation of the precision matrix corresponding to each way of the tensor, we assume the data follow a tensor normal distribution whose covariance has a Kronecker product structure. The penalized maximum likelihood estimation of this model involves minimizing a non-convex objective function. In spite of the non-convexity of this estimation problem, we prove that an alternating minimization algorithm, which iteratively estimates each sparse precision matrix while fixing the others, attains an estimator with the optimal statistical rate of convergence as well as consistent graph recovery. Notably, such an estimator achieves estimation consistency with only one tensor sample, which is unobserved in previous work. Our theoretical results are backed by thorough numerical studies. PMID:28316459

A novel FPGA-programmable switch matrix interconnection element in quantum-dot cellular automata

NASA Astrophysics Data System (ADS)

Hashemi, Sara; Rahimi Azghadi, Mostafa; Zakerolhosseini, Ali; Navi, Keivan

2015-04-01

The Quantum-dot cellular automata (QCA) is a novel nanotechnology, promising extra low-power, extremely dense and very high-speed structure for the construction of logical circuits at a nanoscale. In this paper, initially previous works on QCA-based FPGA's routing elements are investigated, and then an efficient, symmetric and reliable QCA programmable switch matrix (PSM) interconnection element is introduced. This element has a simple structure and offers a complete routing capability. It is implemented using a bottom-up design approach that starts from a dense and high-speed 2:1 multiplexer and utilise it to build the target PSM interconnection element. In this study, simulations of the proposed circuits are carried out using QCAdesigner, a layout and simulation tool for QCA circuits. The results demonstrate high efficiency of the proposed designs in QCA-based FPGA routing.

Cerebrospinal fluid levels of matrix metalloproteinase-9 and tissue inhibitor of metalloproteinase-1 in subacute sclerosing panencephalitis.

PubMed

Ichiyama, Takashi; Matsushige, Takeshi; Siba, Peter; Suarkia, Dagwin; Takasu, Toshiaki; Miki, Kenji; Furukawa, Susumu

2008-05-01

To investigate the brain inflammation and damage in subacute sclerosing panencephalitis (SSPE), the cerebrospinal fluid (CSF) concentrations of matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of metalloproteinase-1 (TIMP-1) were determined in SSPE patients. CSF MMP-9 and TIMP-1 levels were measured in 23 patients with SSPE in Papua New Guinea by ELISA. CSF MMP-9 levels and MMP-9/TIMP-1 ratios of SSPE patients were significantly higher than controls (p<0.001 and p=0.005, respectively). There were no significant differences in CSF TIMP-1 levels between SSPE patients and controls. Previous studies suggested that CSF MMP-9 levels reflect inflammatory damage to the brain. Our findings suggest that the MMP-9 level in CSF is an indicator of inflammatory damage to the brain in SSPE.

Macrophage involvement affects matrix stiffness-related influences on cell osteogenesis under three-dimensional culture conditions.

PubMed

He, Xiao-Tao; Wu, Rui-Xin; Xu, Xin-Yue; Wang, Jia; Yin, Yuan; Chen, Fa-Ming

2018-04-15

Accumulating evidence indicates that the physicochemical properties of biomaterials exert profound influences on stem cell fate decisions. However, matrix-based regulation selected through in vitro analyses based on a given cell population do not genuinely reflect the in vivo conditions, in which multiple cell types are involved and interact dynamically. This study constitutes the first investigation of how macrophages (Mφs) in stiffness-tunable transglutaminase cross-linked gelatin (TG-gel) affect the osteogenesis of bone marrow-derived mesenchymal stem cells (BMMSCs). When a single cell type was cultured, low-stiffness TG-gels promoted BMMSC proliferation, whereas high-stiffness TG-gels supported cell osteogenic differentiation. However, Mφs in high-stiffness TG-gels were more likely to polarize toward the pro-inflammatory M1 phenotype. Using either conditioned medium (CM)-based incubation or Transwell-based co-culture, we found that Mφs encapsulated in the low-stiffness matrix exerted a positive effect on the osteogenesis of co-cultured BMMSCs. Conversely, Mφs in high-stiffness TG-gels negatively affected cell osteogenic differentiation. When both cell types were cultured in the same TG-gel type and placed into the Transwell system, the stiffness-related influences of Mφs on BMMSCs were significantly altered; both the low- and high-stiffness matrix induced similar levels of BMMSC osteogenesis. Although the best material parameter for synergistically affecting Mφs and BMMSCs remains unknown, our data suggest that Mφ involvement in the co-culture system alters previously identified material-related influences on BMMSCs, such as matrix stiffness-related effects, which were identified based on a culture system involving a single cell type. Such Mφ-stem cell interactions should be considered when establishing proper matrix parameter-associated cell regulation in the development of biomimetic biomaterials for regenerative applications. The substrate stiffness of a scaffold plays critical roles in modulating both reparative cells, such as mesenchymal stem cells (MSCs), and immune cells, such as macrophages (Mφs). Although the influences of material stiffness on either Mφs or MSCs, have been extensively described, how the two cell types respond to matrix cues to dynamically affect each other in a three-dimensional (3D) biosystem remains largely unknown. Here, we report our findings that, in a platform wherein Mφs and bone marrow-derived MSCs coexist, matrix stiffness can influence stem cell fate through both direct matrix-associated regulation and indirect Mφ-based modulation. Our data support future studies of the MSC-Mφ-matrix interplay in the 3D context to optimize matrix parameters for the development of the next biomaterial. Copyright © 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Changes in cortical cytoskeletal and extracellular matrix gene expression in prostate cancer are related to oncogenic ERG deregulation.

PubMed

Schulz, Wolfgang A; Ingenwerth, Marc; Djuidje, Carolle E; Hader, Christiane; Rahnenführer, Jörg; Engers, Rainer

2010-09-22

The cortical cytoskeleton network connects the actin cytoskeleton to various membrane proteins, influencing cell adhesion, polarity, migration and response to extracellular signals. Previous studies have suggested changes in the expression of specific components in prostate cancer, especially of 4.1 proteins (encoded by EPB41 genes) which form nodes in this network. Expression of EPB41L1, EPB41L2, EPB41L3 (protein: 4.1B), EPB41L4B (EHM2), EPB41L5, EPB49 (dematin), VIL2 (ezrin), and DLG1 (summarized as "cortical cytoskeleton" genes) as well as ERG was measured by quantitative RT-PCR in a well-characterized set of 45 M0 prostate adenocarcinoma and 13 benign tissues. Hypermethylation of EPB41L3 and GSTP1 was compared in 93 cancer tissues by methylation-specific PCR. Expression of 4.1B was further studied by immunohistochemistry. EPB41L1 and EPB41L3 were significantly downregulated and EPB41L4B was upregulated in cancer tissues. Low EPB41L1 or high EPB41L4B expression were associated with earlier biochemical recurrence. None of the other cortical cytoskeleton genes displayed expression changes, in particular EPB49 and VIL2, despite hints from previous studies. EPB41L3 downregulation was significantly associated with hypermethylation of its promoter and strongly correlated with GSTP1 hypermethylation. Protein 4.1B was detected most strongly in the basal cells of normal prostate epithelia. Its expression in carcinoma cells was similar to the weaker one in normal luminal cells. EPB41L3 downregulation and EPB41L4B upregulation were essentially restricted to the 22 cases with ERG overexpression. Expression changes in EPB41L3 and EPB41L4B closely paralleled those previously observed for the extracellular matrix genes FBLN1 and SPOCK1, respectively. Specific changes in the cortical cytoskeleton were observed during prostate cancer progression. They parallel changes in the expression of extracellular matrix components and all together appear to be associated with oncogenic ERG overexpression. We hypothesize that these alterations may contribute to the increased invasivity conferred to prostate cancer cells by ERG deregulation.

Immunocytochemical localization of amelogenin in rat incisor ameloblasts using ultrathin frozen sections.

PubMed

Nishikawa, S; Takagi, T; Sasa, S

1990-01-01

The localization of amelogenin, an enamel matrix protein, was examined by ultrastructural immunocytochemistry using unembedded ultrathin frozen sections of undecalcified rat incisor ameloblasts. Antibody against bovine amelogenin labeled Golgi complexes, secretory granules, and lysosomal structures in the preameloblasts and inner enamel-secretory ameloblasts as well as the enamel. The antibody also labeled dentin matrix facing preameloblasts. These results support the findings in previous reports using conventional epon embedded specimens. However, rough-surfaced endoplasmic reticulum failed to be labeled by this antibody.

Linear matrix inequality approach to exponential synchronization of a class of chaotic neural networks with time-varying delays

NASA Astrophysics Data System (ADS)

Wu, Wei; Cui, Bao-Tong

2007-07-01

In this paper, a synchronization scheme for a class of chaotic neural networks with time-varying delays is presented. This class of chaotic neural networks covers several well-known neural networks, such as Hopfield neural networks, cellular neural networks, and bidirectional associative memory networks. The obtained criteria are expressed in terms of linear matrix inequalities, thus they can be efficiently verified. A comparison between our results and the previous results shows that our results are less restrictive.

Affine Projection Algorithm with Improved Data-Selective Method Using the Condition Number

NASA Astrophysics Data System (ADS)

Ban, Sung Jun; Lee, Chang Woo; Kim, Sang Woo

Recently, a data-selective method has been proposed to achieve low misalignment in affine projection algorithm (APA) by keeping the condition number of an input data matrix small. We present an improved method, and a complexity reduction algorithm for the APA with the data-selective method. Experimental results show that the proposed algorithm has lower misalignment and a lower condition number for an input data matrix than both the conventional APA and the APA with the previous data-selective method.

Nucleon matrix elements with Nf=2+1+1 maximally twisted fermions

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

Simon Dinter, Constantia Alexandrou, Martha Constantinou, Vincent Drach, Karl Jansen, Dru Renner

2010-06-01

We present the first lattice calculation of nucleon matrix elements using four dynamical flavors. We use the Nf=2+1+1 maximally twisted mass formulation. The renormalization is performed non-perturbatively in the RI'-MOM scheme and results are given for the vector and axial vector operators with up to one-derivative. Our calculation of the average momentum of the unpolarized non-singlet parton distribution is presented and compared to our previous results obtained from the Nf=2 case.

GR@PPA 2.8: Initial-state jet matching for weak-boson production processes at hadron collisions

NASA Astrophysics Data System (ADS)

Odaka, Shigeru; Kurihara, Yoshimasa

2012-04-01

The initial-state jet matching method introduced in our previous studies has been applied to the event generation of single W and Z production processes and diboson (WW, WZ and ZZ) production processes at hadron collisions in the framework of the GR@PPA event generator. The generated events reproduce the transverse momentum spectra of weak bosons continuously in the entire kinematical region. The matrix elements (ME) for hard interactions are still at the tree level. As in previous versions, the decays of weak bosons are included in the matrix elements. Therefore, spin correlations and phase-space effects in the decay of weak bosons are exact at the tree level. The program package includes custom-made parton shower programs as well as ME-based hard interaction generators in order to achieve self-consistent jet matching. The generated events can be passed to general-purpose event generators to make the simulation proceed down to the hadron level. Catalogue identifier: ADRH_v3_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADRH_v3_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.: 112 146 No. of bytes in distributed program, including test data, etc.: 596 667 Distribution format: tar.gz Programming language: Fortran; with some included libraries coded in C and C++ Computer: All Operating system: Any UNIX-like system RAM: 1.6 Mega bytes at minimum Classification: 11.2 Catalogue identifier of previous version: ADRH_v2_0 Journal reference of previous version: Comput. Phys. Comm. 175 (2006) 665 External routines: Bash and Perl for the setup, and CERNLIB, ROOT, LHAPDF, PYTHIA according to the user's choice. Does the new version supersede the previous version?: No, this version supports only a part of the processes included in the previous versions. Nature of problem: We need to combine those processes including 0 jet and 1 jet in the matrix elements using an appropriate matching method, in order to simulate weak-boson production processes in the entire kinematical region. Solution method: The leading logarithmic components to be included in parton distribution functions and parton showers are subtracted from 1-jet matrix elements. Custom-made parton shower programs are provided to ensure satisfactory performance of the matching method. Reasons for new version: An initial-state jet matching method has been implemented. Summary of revisions: Weak-boson production processes associated with 0 jet and 1 jet can be consistently merged using the matching method. Restrictions: The built-in parton showers are not compatible with the PYTHIA new PS and the HERWIG PS. Unusual features: A large number of particles may be produced by the parton showers and passed to general-purpose event generators. Running time: About 10 min for initialization plus 25 s for every 1k-event generation for W production in the LHC condition, on a 3.0-GHz Intel Xeon processor with the default setting.

A comparison of companion matrix methods to find roots of a trigonometric polynomial

NASA Astrophysics Data System (ADS)

Boyd, John P.

2013-08-01

A trigonometric polynomial is a truncated Fourier series of the form fN(t)≡∑j=0Naj cos(jt)+∑j=1N bj sin(jt). It has been previously shown by the author that zeros of such a polynomial can be computed as the eigenvalues of a companion matrix with elements which are complex valued combinations of the Fourier coefficients, the "CCM" method. However, previous work provided no examples, so one goal of this new work is to experimentally test the CCM method. A second goal is introduce a new alternative, the elimination/Chebyshev algorithm, and experimentally compare it with the CCM scheme. The elimination/Chebyshev matrix (ECM) algorithm yields a companion matrix with real-valued elements, albeit at the price of usefulness only for real roots. The new elimination scheme first converts the trigonometric rootfinding problem to a pair of polynomial equations in the variables (c,s) where c≡cos(t) and s≡sin(t). The elimination method next reduces the system to a single univariate polynomial P(c). We show that this same polynomial is the resultant of the system and is also a generator of the Groebner basis with lexicographic ordering for the system. Both methods give very high numerical accuracy for real-valued roots, typically at least 11 decimal places in Matlab/IEEE 754 16 digit floating point arithmetic. The CCM algorithm is typically one or two decimal places more accurate, though these differences disappear if the roots are "Newton-polished" by a single Newton's iteration. The complex-valued matrix is accurate for complex-valued roots, too, though accuracy decreases with the magnitude of the imaginary part of the root. The cost of both methods scales as O(N3) floating point operations. In spite of intimate connections of the elimination/Chebyshev scheme to two well-established technologies for solving systems of equations, resultants and Groebner bases, and the advantages of using only real-valued arithmetic to obtain a companion matrix with real-valued elements, the ECM algorithm is noticeably inferior to the complex-valued companion matrix in simplicity, ease of programming, and accuracy.

Infrared study of matrix-isolated ethyl cyanide: simulation of the photochemistry in the atmosphere of Titan.

PubMed

Toumi, A; Piétri, N; Couturier-Tamburelli, I

2015-11-11

Low-temperature Ar matrix isolation has been carried out to investigate the infrared spectrum of ethyl cyanide (CH3CH2CN), a molecule present in the atmosphere of Titan. The λ > 120 nm and λ > 230 nm photolysis reactions of ethyl cyanide in an Ar matrix were also performed in order to compare the behaviour of this compound when it is submitted to high and low energetic radiations. These different wavelengths have been used with the aim to reproduce the radiation reaching the various parts of the atmosphere. Several photoproducts have been identified during photolysis such as vinyl cyanide (CH2[double bond, length as m-dash]CHCN), cyanoacetylene (HC3N), and ethylene/hydrogen cyanide (C2H4/HCN), ethylene/hydrogen isocyanide (C2H4/HNC), acetylene/hydrogen cyanide (C2H2/HCN), acetylene/hydrogen isocyanide (C2H2/HNC), and acetylene:methylenimine (C2H2:HNCH2) complexes. Ethyl isocyanide (CH3CH2NC) and a ketenimine form (CH3CH[double bond, length as m-dash]C[double bond, length as m-dash]NH) have been identified as well. Photoproduct identification and spectral assignments were done using previous studies and density functional theory (DFT) calculations with the B3LYP/cc-pVTZ basis set.

Increased mitochondrial matrix directed superoxide production by fatty acid hydroperoxides in skeletal muscle mitochondria

PubMed Central

Bhattacharya, Arunabh; Lustgarten, Michael; Shi, Yun; Liu, Yuhong; Jang, Youngmok C; Pulliam, Daniel; Jernigan, Amanda L; Van Remmen, Holly

2013-01-01

Previous studies have shown that muscle atrophy is associated with mitochondrial dysfunction and an increased rate of mitochondrial reactive oxygen species production. We recently demonstrated that fatty acid hydroperoxides (FA-OOH) are significantly elevated in mitochondria isolated from atrophied muscles. The purpose of the current study is to determine whether FA-OOH can alter skeletal muscle mitochondrial function. We found that FA-OOH (at low micromolar concentrations) induces mitochondrial dysfunction assessed by decrease in the rate of ATP production, oxygen consumption and activity of respiratory chain complexes I and III. Using methods to distinguish superoxide release towards the matrix and inter-membrane space, we demonstrate that FA-OOH significantly elevates oxidative stress in the mitochondrial matrix (and not the inter-membrane space) with complex I as the major site of superoxide production (most likely from a site upstream of the ubiquinone binding site but downstream from the flavin binding site-the iron sulfur clusters). Our results are the first to indicate that FA-OOH’s are important modulators of mitochondrial function and oxidative stress in skeletal muscle mitochondria and may play an important role in muscle atrophies that are associated with increased generation of FA-OOH’s, e.g., denervation-induced muscle atrophy. PMID:21172427

Free space optical communication using beam parameters with translational and transverse rotational invariance.

PubMed

Ivan, J Solomon; Goswami, Kaumudibikash

2015-06-01

Two natural requirements on a measurable quantity possessed by a paraxially propagating light-field to be suitable for free space optical communication are invariance under free space propagation and invariance under transverse plane rotation. While the former invariance ensures that the measurable quantity is robust while signalling through free space, the latter invariance ensures that a detector measuring the quantity can be oriented at any angle in the transverse plane, and a measurement by the detector yields the same value for the quantity irrespective of the transverse angle, thus avoiding alignment issues. The variance matrix of a paraxially propagating light-field is analyzed from the perspective of the aforementioned invariances. That the "charge" of a paraxial light-field, which is contained in the variance matrix, and which has been previously well studied for its suitability toward free space optical communication, possesses these two invariance properties, emerges naturally in the analysis. Seven functionally independent quantities other than charge, which are derived from the variance matrix, and which share these invariances, are presented and studied for their suitability toward signalling through turbulent atmosphere using the low-order Hermite-Gaussian modes. It is found that the spot size of a Gaussian light-field can be effectively used as a switch, to communicate through short distances in a turbulent atmosphere.

Strontium-doped hydroxyapatite polysaccharide materials effect on ectopic bone formation

PubMed Central

Aid-Launais, R.; Sagardoy, T.; Siadous, R.; Bareille, R.; Rey, S.; Pechev, S.; Etienne, L.; Kalisky, J.; de Mones, E.; Letourneur, D.; Amedee Vilamitjana, J.

2017-01-01

Previous studies performed using polysaccharide-based matrices supplemented with hydroxyapatite (HA) particles showed their ability to form in subcutaneous and intramuscular sites a mineralized and osteoid tissue. Our objectives are to optimize the HA content in the matrix and to test the combination of HA with strontium (Sr-HA) to increase the matrix bioactivity. First, non-doped Sr-HA powders were combined to the matrix at three different ratios and were implanted subcutaneously for 2 and 4 weeks. Interestingly, matrices showed radiolucent properties before implantation. Quantitative analysis of micro-CT data evidenced a significant increase of mineralized tissue formed ectopically with time of implantation and allowed us to select the best ratio of HA to polysaccharides of 30% (w/w). Then, two Sr-substitution of 8% and 50% were incorporated in the HA powders (8Sr-HA and 50Sr-HA). Both Sr-HA were chemically characterized and dispersed in matrices. In vitro studies performed with human mesenchymal stem cells (MSCs) demonstrated the absence of cytotoxicity of the Sr-doped matrices whatever the amount of incorporated Sr. They also supported osteoblastic differentiation and activated the expression of one late osteoblastic marker involved in the mineralization process i.e. osteopontin. In vivo, subcutaneous implantation of these Sr-doped matrices induced osteoid tissue and blood vessels formation. PMID:28910401

Conserved G-matrices of morphological and life-history traits among continental and island blue tit populations.

PubMed

Delahaie, B; Charmantier, A; Chantepie, S; Garant, D; Porlier, M; Teplitsky, C

2017-08-01

The genetic variance-covariance matrix (G-matrix) summarizes the genetic architecture of multiple traits. It has a central role in the understanding of phenotypic divergence and the quantification of the evolutionary potential of populations. Laboratory experiments have shown that G-matrices can vary rapidly under divergent selective pressures. However, because of the demanding nature of G-matrix estimation and comparison in wild populations, the extent of its spatial variability remains largely unknown. In this study, we investigate spatial variation in G-matrices for morphological and life-history traits using long-term data sets from one continental and three island populations of blue tit (Cyanistes caeruleus) that have experienced contrasting population history and selective environment. We found no evidence for differences in G-matrices among populations. Interestingly, the phenotypic variance-covariance matrices (P) were divergent across populations, suggesting that using P as a substitute for G may be inadequate. These analyses also provide the first evidence in wild populations for additive genetic variation in the incubation period (that is, the period between last egg laid and hatching) in all four populations. Altogether, our results suggest that G-matrices may be stable across populations inhabiting contrasted environments, therefore challenging the results of previous simulation studies and laboratory experiments.

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

Rementeria, Rosalia; Poplawsky, Jonathan D.; Aranda, Maria M.

Current studies using atom probe tomography (APT) show that bainitic ferrite formed at low temperature contains more carbon than what is consistent with the paraequilibrium phase diagram. However, nanocrystalline bainitic ferrite exhibits a non-homogeneous distribution of carbon atoms in arrangements with specific compositions, i.e. Cottrell atmospheres, carbon clusters, and carbides, in most cases with a size of a few nanometers. The ferrite volume within a single platelet that is free of these carbon-enriched regions is extremely small. Proximity histograms can be compromised on the ferrite side, and a great deal of care should be taken to estimate the carbon contentmore » in regions of bainitic ferrite free from carbon agglomeration. For this purpose, APT measurements were first validated for the ferritic phase in a pearlitic sample and further performed for the bainitic ferrite matrix in high-silicon steels isothermally transformed between 200 °C and 350 °C. Additionally, results were compared with the carbon concentration values derived from X-ray diffraction (XRD) analyses considering a tetragonal lattice and previous APT studies. In conclusion, the present results reveal a strong disagreement between the carbon content values in the bainitic ferrite matrix as obtained by APT and those derived from XRD measurements. Those differences have been attributed to the development of carbon-clustered regions with an increased tetragonality in a carbon-depleted matrix.« less

The nonchromatin substructures of the nucleus: the ribonucleoprotein (RNP)-containing and RNP-depleted matrices analyzed by sequential fractionation and resinless section electron microscopy

PubMed Central

1986-01-01

The nonchromatin structure or matrix of the nucleus has been studied using an improved fractionation in concert with resinless section electron microscopy. The resinless sections show the nucleus of the intact cell to be filled with a dense network or lattice composed of soluble proteins and chromatin in addition to the structural nuclear constituents. In the first fractionation step, soluble proteins are removed by extraction with Triton X-100, and the dense nuclear lattice largely disappears. Chromatin and nonchromatin nuclear fibers are now sharply imaged. Nuclear constituents are further separated into three well-defined, distinct protein fractions. Chromatin proteins are those that require intact DNA for their association with the nucleus and are released by 0.25 M ammonium sulfate after internucleosomal DNA is cut with DNAase I. The resulting structure retains most heterogeneous nuclear ribonucleoprotein (hnRNP) and is designated the RNP-containing nuclear matrix. The proteins of hnRNP are those associated with the nucleus only if RNA is intact. These are released when nuclear RNA is briefly digested with RNAase A. Ribonuclease digestion releases 97% of the hnRNA and its associated proteins. These proteins correspond to the hnRNP described by Pederson (Pederson, T., 1974, J. Mol. Biol., 83:163- 184) and are distinct from the proteins that remain in the ribonucleoprotein (RNP)-depleted nuclear matrix. The RNP-depleted nuclear matrix is a core structure that retains lamins A and C, the intermediate filaments, and a unique set of nuclear matrix proteins (Fey, E. G., K. M. Wan, and S. Penman, 1984, J. Cell Biol. 98:1973- 1984). This core had been previously designated the nuclear matrix- intermediate filament scaffold and its proteins are a third, distinct, and nonoverlapping subset of the nuclear nonhistone proteins. Visualizing the nuclear matrix using resinless sections shows that nuclear RNA plays an important role in matrix organization. Conventional Epon-embedded electron microscopy sections show comparatively little of the RNP-containing and RNP-depleted nuclear matrix structure. In contrast, resinless sections show matrix interior to be a three-dimensional network of thick filaments bounded by the nuclear lamina. The filaments are covered with 20-30-nm electron dense particles which may contain the hnRNA. The large electron dense bodies, enmeshed in the interior matrix fibers, have the characteristic morphology of nucleoli. Treatment of the nuclear matrix with RNAase results in the aggregation of the interior fibers and the extensive loss of the 20-30-nm particles.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:3700470

The Study of Leukocyte Functions in a Rotating Wall Vessel

NASA Technical Reports Server (NTRS)

Trial, JoAnn

1998-01-01

The objective of this study was to investigate the behavior of leukocytes under free-fall conditions in a rotating wall vessel. In such a vessel, the tendency of a cell to fall in response to gravity is opposed by the rotation of the vessel and the culture medium within, keeping the cells in suspension without fluid shear. Previous reports indicated that such functions as lymphocyte migration through collagen matrix or monocyte cytokine secretion are altered under these conditions, and these changes correlate with similar functional defects of cultured cells seen during spaceflight.

Degree of Approximation by a General Cλ -Summability Method

NASA Astrophysics Data System (ADS)

Sonker, S.; Munjal, A.

2018-03-01

In the present study, two theorems explaining the degree of approximation of signals belonging to the class Lip(α, p, w) by a more general C λ -method (Summability method) have been formulated. Improved estimations have been observed in terms of λ(n) where (λ(n))‑α ≤ n ‑α for 0 < α ≤ 1 as compared to previous studies presented in terms of n. These estimations of infinite matrices are very much applicable in solid state physics which further motivates for an investigation of perturbations of matrix valued functions.

Chaotic itinerancy in the oscillator neural network without Lyapunov functions.

PubMed

Uchiyama, Satoki; Fujisaka, Hirokazu

2004-09-01

Chaotic itinerancy (CI), which is defined as an incessant spontaneous switching phenomenon among attractor ruins in deterministic dynamical systems without Lyapunov functions, is numerically studied in the case of an oscillator neural network model. The model is the pseudoinverse-matrix version of the previous model [S. Uchiyama and H. Fujisaka, Phys. Rev. E 65, 061912 (2002)] that was studied theoretically with the aid of statistical neurodynamics. It is found that CI in neural nets can be understood as the intermittent dynamics of weakly destabilized chaotic retrieval solutions. Copyright 2004 American Institute of Physics

Lucigenin-dependent chemiluminescence in articular chondrocytes.

PubMed

Rathakrishnan, C; Tiku, M L

1993-08-01

We were recently able to measure intracellular levels of hydrogen peroxide within normal articular chondrocytes using the trapped indicator 2',7'-dichlorofluorescein diacetate. Further studies have shown that stimulated chondrocytes produce luminol-dependent chemiluminescence, suggesting that these cells produce hydrogen peroxide and singlet oxygen. In the present study, we have investigated the lucigenin-dependent chemiluminescence response in normal articular chondrocytes. Chondrocytes either in suspension or adhered to cover slips showed lucigenin-dependent chemiluminescence. There was a dose-dependent increase in chemiluminescence response when chondrocytes were incubated with soluble stimuli like phorbol-myristate-acetate, concanavalin A, and f-met-leu-phe. Catalase and the metabolic inhibitor, sodium azide, which inhibits the enzyme myeloperoxidase, had no inhibitory effect on lucigenin-dependent chemiluminescence production. Only the antioxidant, superoxide dismutase, prevented lucigenin-dependent chemiluminescence, indicating that this assay measures the production of superoxide anions by chondrocytes. We confirmed that chondrocytes release superoxide radicals using the biochemical assay of ferricytochrome c reduction. Since cartilage tissue is semi-transparent, we were able to measure chemiluminescence response in live cartilage tissue, showing that chondrocytes which are embedded within the matrix can also generate superoxide anion radicals. Reactive oxygen intermediates have been shown to play a significant role in the degradation of matrix in arthritis. Our previous and present studies suggest that oxygen radicals produced by chondrocytes may be an important mechanism by which chondrocytes induce cartilage matrix degradation.

Development of a Calcifiable Matrix for Bone Formation.

DTIC Science & Technology

1987-09-01

Previous editions are obsolete. SECURITY CLASSIFICATION OF THIS PAGE 4 ! Ir .€ w)N "," f " f " W"€ r ,. . , a v " -.-. ,. . P "w...process is hydroxyapatite *o(15). It was the purpose of our study to determine if three different doses of -.ofour variations of the polypentapeptide...phosphate would bind until a cascading series of events led to calcium phosphate deposition and its conversion to hydroxyapatite . The validity of this

Reduction of Burn Progression with Topical Delivery of (Antitumor Necrosis Factor-alpha )-Hyaluronic Acid Conjugates

DTIC Science & Technology

2012-01-01

antibody conjugation to HA The conjugation chemistry followed a method previously developed in our laboratory. Briefly, HA (12 mg) was modi - fied...Webster MW, McGill JB, Schwartz SL. Promotion and acceleration of diabetic ulcer healing by arginine-glycine-aspartic acid (RGD) peptide matrix. RGD...Study Group. Diabetes Care 1995; 18: 39–46. 32. Ho-Asjoe M, Chronnell CM, Frame JD, Leigh IM, Carver N. Immunohistochemical analysis of burn depth. J

Separable Ernst-Shakin-Thaler expansions of local potentials

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

Bund, G.W.

The boundary condition Ernst-Shakin-Thaler method, introduced previously to generate separable expansions of local potentials of finite range, is applied to the study of the triplet s-wave Malfliet-Tjon potential. The effect of varying the radius where the boundary condition is applied on the T matrix is analyzed. Further, we compare the convergence of the n-d scattering cross sections in the quartet state below the breakup threshold for expansions corresponding to two different boundaries.

Novel Approach for Positioning Sensor Lead Wires on SiC-Based Monolithic Ceramic and FRCMC Components/Subcomponents Having Flat and Curved Surfaces

NASA Technical Reports Server (NTRS)

Kiser, J. Douglas; Singh, Mrityunjay; Lei, Jin-Fen; Martin, Lisa C.

1999-01-01

A novel attachment approach for positioning sensor lead wires on silicon carbide-based monolithic ceramic and fiber reinforced ceramic matrix composite (FRCMC) components has been developed. This approach is based on an affordable, robust ceramic joining technology, named ARCJoinT, which was developed for the joining of silicon carbide-based ceramic and fiber reinforced composites. The ARCJoinT technique has previously been shown to produce joints with tailorable thickness and good high temperature strength. In this study, silicon carbide-based ceramic and FRCMC attachments of different shapes and sizes were joined onto silicon carbide fiber reinforced silicon carbide matrix (SiC/ SiC) composites having flat and curved surfaces. Based on results obtained in previous joining studies. the joined attachments should maintain their mechanical strength and integrity at temperatures up to 1350 C in air. Therefore they can be used to position and secure sensor lead wires on SiC/SiC components that are being tested in programs that are focused on developing FRCMCs for a number of demanding high temperature applications in aerospace and ground-based systems. This approach, which is suitable for installing attachments on large and complex shaped monolithic ceramic and composite components, should enhance the durability of minimally intrusive high temperature sensor systems. The technology could also be used to reinstall attachments on ceramic components that were damaged in service.

Development of Thioaryl-Based Matrix Metalloproteinase-12 Inhibitors with Alternative Zinc-Binding Groups: Synthesis, Potentiometric, NMR, and Crystallographic Studies.

PubMed

Nuti, Elisa; Cuffaro, Doretta; Bernardini, Elisa; Camodeca, Caterina; Panelli, Laura; Chaves, Sílvia; Ciccone, Lidia; Tepshi, Livia; Vera, Laura; Orlandini, Elisabetta; Nencetti, Susanna; Stura, Enrico A; Santos, M Amélia; Dive, Vincent; Rossello, Armando

2018-05-24

Matrix metalloproteinase-12 (MMP-12) selective inhibitors could play a role in the treatment of lung inflammatory and cardiovascular diseases. In the present study, the previously reported 4-methoxybiphenylsulfonyl hydroxamate and carboxylate based inhibitors (1b and 2b) were modified to enhance their selectivity for MMP-12. In the newly synthesized thioaryl derivatives, the nature of the zinc binding group (ZBG) and the sulfur oxidation state were changed. Biological assays carried out in vitro on human MMPs with the resulting compounds led to identification of a sulfide, 4a, bearing an N-1-hydroxypiperidine-2,6-dione (HPD) group as new ZBG. Compound 4a is a promising hit compound since it displayed a nanomolar affinity for MMP-12 with a marked selectivity over MMP-9, MMP-1, and MMP-14. Solution complexation studies with Zn 2+ were performed to characterize the chelating abilities of the new compounds and confirmed the bidentate binding mode of HPD derivatives. X-ray crystallography studies using MMP-12 and MMP-9 catalytic domains were carried out to rationalize the biological results.

Search for Majorana Neutrinos Near the Inverted Mass Hierarchy Region with KamLAND-Zen

NASA Astrophysics Data System (ADS)

Gando, A.; Gando, Y.; Hachiya, T.; Hayashi, A.; Hayashida, S.; Ikeda, H.; Inoue, K.; Ishidoshiro, K.; Karino, Y.; Koga, M.; Matsuda, S.; Mitsui, T.; Nakamura, K.; Obara, S.; Oura, T.; Ozaki, H.; Shimizu, I.; Shirahata, Y.; Shirai, J.; Suzuki, A.; Takai, T.; Tamae, K.; Teraoka, Y.; Ueshima, K.; Watanabe, H.; Kozlov, A.; Takemoto, Y.; Yoshida, S.; Fushimi, K.; Banks, T. I.; Berger, B. E.; Fujikawa, B. K.; O'Donnell, T.; Winslow, L. A.; Efremenko, Y.; Karwowski, H. J.; Markoff, D. M.; Tornow, W.; Detwiler, J. A.; Enomoto, S.; Decowski, M. P.; KamLAND-Zen Collaboration

2016-08-01

We present an improved search for neutrinoless double-beta (0 ν β β ) decay of 136Xe in the KamLAND-Zen experiment. Owing to purification of the xenon-loaded liquid scintillator, we achieved a significant reduction of the Agm110 contaminant identified in previous searches. Combining the results from the first and second phase, we obtain a lower limit for the 0 ν β β decay half-life of T1/2 0 ν>1.07 ×1 026 yr at 90% C.L., an almost sixfold improvement over previous limits. Using commonly adopted nuclear matrix element calculations, the corresponding upper limits on the effective Majorana neutrino mass are in the range 61-165 meV. For the most optimistic nuclear matrix elements, this limit reaches the bottom of the quasidegenerate neutrino mass region.

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.

Charge-Transfer Complexes and Photochemistry of Ozone with Ferrocene and n-Butylferrocene: A UV-vis Matrix-Isolation Study.

PubMed

Pinelo, Laura F; Kugel, Roger W; Ault, Bruce S

2015-10-15

The reactions of ozone with ferrocene (cp2Fe) and with n-butylferrocene (n-butyl cp2Fe) were studied using matrix isolation, UV-vis spectroscopy, and theoretical calculations. The codeposition of cp2Fe with O3 and of n-butyl cp2Fe with O3 into an argon matrix led to the production of 1:1 charge-transfer complexes with absorptions at 765 and 815 nm, respectively. These absorptions contribute to the green matrix color observed upon initial deposition. The charge-transfer complexes underwent photochemical reactions upon irradiation with red light (λ ≥ 600 nm). Theoretical UV-vis spectra of the charge-transfer complexes and photochemical products were calculated using TD-DFT at the B3LYP/6-311G++(d,2p) level of theory. The calculated UV-vis spectra were in good agreement with the experimental results. MO analysis of these long-wavelength transitions showed them to be n→ π* on the ozone subunit in the complex and indicated that the formation of the charge-transfer complex between ozone and cp2Fe or n-butyl cp2Fe affects how readily the π* orbital on O3 is populated when red light (λ ≥ 600 nm) is absorbed. 1:1 complexes of cp2Fe and n-butyl cp2Fe with O2 were also observed experimentally and calculated theoretically. These results support and enhance previous infrared studies of the mechanism of photooxidation of ferrocene by ozone, a reaction that has considerable significance for the formation of iron oxide thin films for a range of applications.

Imaging MALDI MS of Dosed Brain Tissues Utilizing an Alternative Analyte Pre-extraction Approach

NASA Astrophysics Data System (ADS)

Quiason, Cristine M.; Shahidi-Latham, Sheerin K.

2015-06-01

Matrix-assisted laser desorption ionization (MALDI) imaging mass spectrometry has been adopted in the pharmaceutical industry as a useful tool to detect xenobiotic distribution within tissues. A unique sample preparation approach for MALDI imaging has been described here for the extraction and detection of cobimetinib and clozapine, which were previously undetectable in mouse and rat brain using a single matrix application step. Employing a combination of a buffer wash and a cyclohexane pre-extraction step prior to standard matrix application, the xenobiotics were successfully extracted and detected with an 8 to 20-fold gain in sensitivity. This alternative approach for sample preparation could serve as an advantageous option when encountering difficult to detect analytes.

Statistics of time delay and scattering correlation functions in chaotic systems. II. Semiclassical approximation

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

Novaes, Marcel

2015-06-15

We consider S-matrix correlation functions for a chaotic cavity having M open channels, in the absence of time-reversal invariance. Relying on a semiclassical approximation, we compute the average over E of the quantities Tr[S{sup †}(E − ϵ) S(E + ϵ)]{sup n}, for general positive integer n. Our result is an infinite series in ϵ, whose coefficients are rational functions of M. From this, we extract moments of the time delay matrix Q = − iħS{sup †}dS/dE and check that the first 8 of them agree with the random matrix theory prediction from our previous paper [M. Novaes, J. Math. Phys.more » 56, 062110 (2015)].« less

Random Matrix Approach for Primal-Dual Portfolio Optimization Problems

NASA Astrophysics Data System (ADS)

Tada, Daichi; Yamamoto, Hisashi; Shinzato, Takashi

2017-12-01

In this paper, we revisit the portfolio optimization problems of the minimization/maximization of investment risk under constraints of budget and investment concentration (primal problem) and the maximization/minimization of investment concentration under constraints of budget and investment risk (dual problem) for the case that the variances of the return rates of the assets are identical. We analyze both optimization problems by the Lagrange multiplier method and the random matrix approach. Thereafter, we compare the results obtained from our proposed approach with the results obtained in previous work. Moreover, we use numerical experiments to validate the results obtained from the replica approach and the random matrix approach as methods for analyzing both the primal and dual portfolio optimization problems.

Simultaneous Separation of Actinium and Radium Isotopes from a Proton Irradiated Thorium Matrix

DOE PAGES

Mastren, Tara; Radchenko, Valery; Owens, Allison; ...

2017-08-15

A new method has been developed for the isolation of 223,224,225Ra, in high yield and purity, from a proton irradiated 232Th matrix. We report an all-aqueous process using multiple solid-supported adsorption steps including a citrate chelation method developed to remove >99.9% of the barium contaminants by activity from the final radium product. Moreover, we developed a procedure involving the use of three columns in succession, and the separation of 223,224,225Ra from the thorium matrix was obtained with an overall recovery yield of 91 ± 3%, average radiochemical purity of 99.9%, and production yields that correspond to physical yields based onmore » previously measured excitation functions.« less

Robust extraction of basis functions for simultaneous and proportional myoelectric control via sparse non-negative matrix factorization

NASA Astrophysics Data System (ADS)

Lin, Chuang; Wang, Binghui; Jiang, Ning; Farina, Dario

2018-04-01

Objective. This paper proposes a novel simultaneous and proportional multiple degree of freedom (DOF) myoelectric control method for active prostheses. Approach. The approach is based on non-negative matrix factorization (NMF) of surface EMG signals with the inclusion of sparseness constraints. By applying a sparseness constraint to the control signal matrix, it is possible to extract the basis information from arbitrary movements (quasi-unsupervised approach) for multiple DOFs concurrently. Main Results. In online testing based on target hitting, able-bodied subjects reached a greater throughput (TP) when using sparse NMF (SNMF) than with classic NMF or with linear regression (LR). Accordingly, the completion time (CT) was shorter for SNMF than NMF or LR. The same observations were made in two patients with unilateral limb deficiencies. Significance. The addition of sparseness constraints to NMF allows for a quasi-unsupervised approach to myoelectric control with superior results with respect to previous methods for the simultaneous and proportional control of multi-DOF. The proposed factorization algorithm allows robust simultaneous and proportional control, is superior to previous supervised algorithms, and, because of minimal supervision, paves the way to online adaptation in myoelectric control.

One-step direct-laser metal writing of sub-100 nm 3D silver nanostructures in a gelatin matrix

NASA Astrophysics Data System (ADS)

Kang, SeungYeon; Vora, Kevin; Mazur, Eric

2015-03-01

Developing an ability to fabricate high-resolution, 3D metal nanostructures in a stretchable 3D matrix is a critical step to realizing novel optoelectronic devices such as tunable bulk metal-dielectric optical devices and THz metamaterial devices that are not feasible with alternative techniques. We report a new chemistry method to fabricate high-resolution, 3D silver nanostructures using a femtosecond-laser direct metal writing technique. Previously, only fabrication of 3D polymeric structures or single-/few-layer metal structures was possible. Our method takes advantage of unique gelatin properties to overcome such previous limitations as limited freedom in 3D material design and short sample lifetime. We fabricate more than 15 layers of 3D silver nanostructures with a resolution of less than 100 nm in a stable dielectric matrix that is flexible and has high large transparency that is well-matched for potential applications in the optical and THz metamaterial regimes. This is a single-step process that does not require any further processing. This work will be of interest to those interested in fabrication methods that utilize nonlinear light-matter interactions and the realization of future metamaterials.

Orchestin, a calcium-binding phosphoprotein, is a matrix component of two successive transitory calcified biomineralizations cyclically elaborated by a terrestrial crustacean.

PubMed

Hecker, Arnaud; Quennedey, Brigitte; Testenière, Olivier; Quennedey, André; Graf, François; Luquet, Gilles

2004-06-01

Orchestia cavimana is a crustacean that cyclically replaces its calcified cuticle during molting cycles in order to grow. Its terrestrial way of life requires storage of calcium during each premolt period, as calcareous concretions, in tubular diverticula of the midgut. During the postmolt period the stored calcium is reabsorbed and is translocated through the storage organ epithelium as calcified small spherules. In a previous study, we sequenced and characterized a remarkable component of the organic matrix of the premolt storage structures, Orchestin, which is a calcium-binding phosphoprotein. In this paper, we analyzed the spatiotemporal expression of the orchestin gene by Northern blotting and in situ hybridization, and its translated product by immunocytochemistry. We found evidence that the gene and the protein are expressed specifically during premolt in the storage organs. More interestingly, we demonstrated that the protein is synthesized also during the postmolt period, as a component of the organic matrix of the calcium resorption spherules. Thus, Orchestin is a matrix component that is synthesized by the same cells to contribute alternately to the elaboration of two different calcifications. These results, in addition to the physical and chemical features of the protein, suggest that Orchestin is probably a key molecule in the calcium carbonate precipitation process leading to the cyclic elaboration of two transitory calcified mineralizations by the crustacean Orchestia.

Fast screening of short-chain chlorinated paraffins in indoor dust samples by graphene-assisted laser desorption/ionization mass spectrometry.

PubMed

Huang, Xiu; Liu, Qian; Gao, Wei; Wang, Yawei; Nie, Zhou; Yao, Shouzhuo; Jiang, Guibin

2018-03-01

As an important class of emerging chemical contaminants, short-chain chlorinated paraffins (SCCPs) are considered as one of the most challenging groups of compounds to analyze. In this paper, we report a new method for fast screening of SCCPs based on matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) with graphene as a matrix and 2,5,6,9-tetrachlorodecane as an internal standard. We found that the use of graphene as MALDI matrix generated high peak intensities for SCCPs while producing few background noises. The ion fragmentation mechanisms of SCCPs in MALDI are discussed in detail. Under the optimized conditions, much lower detection limits of SCCP congeners (0.1-5ng/mL) than those reported previously were obtained. Other distinct advantages such as short analysis time and simplified sample preparation procedures are also demonstrated. The method was successfully applied in fast screening of SCCPs in indoor dust samples and monitoring of human exposure levels to SCCPs, and the results were verified by gas chromatography coupled to negative chemical ionization quadrupole time-of-flight high-resolution mass spectrometry. This work not only offers a new promising tool for SCCP studies, but also further demonstrates the promise of graphene as a new generation of MALDI matrix. Copyright © 2017 Elsevier B.V. All rights reserved.

"Magic" Ionization Mass Spectrometry

NASA Astrophysics Data System (ADS)

Trimpin, Sarah

2016-01-01

The systematic study of the temperature and pressure dependence of matrix-assisted ionization (MAI) led us to the discovery of the seemingly impossible, initially explained by some reviewers as either sleight of hand or the misinterpretation by an overzealous young scientist of results reported many years before and having little utility. The "magic" that we were attempting to report was that with matrix assistance, molecules, at least as large as bovine serum albumin (66 kDa), are lifted into the gas phase as multiply charged ions simply by exposure of the matrix:analyte sample to the vacuum of a mass spectrometer. Applied heat, a laser, or voltages are not necessary to achieve charge states and ion abundances only previously observed with electrospray ionization (ESI). The fundamentals of how solid phase volatile or nonvolatile compounds are converted to gas-phase ions without added energy currently involves speculation providing a great opportunity to rethink mechanistic understanding of ionization processes used in mass spectrometry. Improved understanding of the mechanism(s) of these processes and their connection to ESI and matrix-assisted laser desorption/ionization may provide opportunities to further develop new ionization strategies for traditional and yet unforeseen applications of mass spectrometry. This Critical Insights article covers developments leading to the discovery of a seemingly magic ionization process that is simple to use, fast, sensitive, robust, and can be directly applied to surface characterization using portable or high performance mass spectrometers.

Refining mortality estimates in shark demographic analyses: a Bayesian inverse matrix approach.

PubMed

Smart, Jonathan J; Punt, André E; White, William T; Simpfendorfer, Colin A

2018-01-18

Leslie matrix models are an important analysis tool in conservation biology that are applied to a diversity of taxa. The standard approach estimates the finite rate of population growth (λ) from a set of vital rates. In some instances, an estimate of λ is available, but the vital rates are poorly understood and can be solved for using an inverse matrix approach. However, these approaches are rarely attempted due to prerequisites of information on the structure of age or stage classes. This study addressed this issue by using a combination of Monte Carlo simulations and the sample-importance-resampling (SIR) algorithm to solve the inverse matrix problem without data on population structure. This approach was applied to the grey reef shark (Carcharhinus amblyrhynchos) from the Great Barrier Reef (GBR) in Australia to determine the demography of this population. Additionally, these outputs were applied to another heavily fished population from Papua New Guinea (PNG) that requires estimates of λ for fisheries management. The SIR analysis determined that natural mortality (M) and total mortality (Z) based on indirect methods have previously been overestimated for C. amblyrhynchos, leading to an underestimated λ. The updated Z distributions determined using SIR provided λ estimates that matched an empirical λ for the GBR population and corrected obvious error in the demographic parameters for the PNG population. This approach provides opportunity for the inverse matrix approach to be applied more broadly to situations where information on population structure is lacking. © 2018 by the Ecological Society of America.

Decorin and biglycan retain LDL in disease-prone valvular and aortic subendothelial intimal matrix

PubMed Central

Neufeld, Edward B.; Zadrozny, Leah M.; Phillips, Darci; Aponte, Angel; Yu, Zu-Xi; Balaban, Robert S.

2014-01-01

Objective Subendothelial LDL retention by intimal matrix proteoglycans is an initial step in atherosclerosis and calcific aortic valve disease. Herein, we identify decorin and biglycan as the proteoglycans that preferentially retain LDL in intimal matrix at disease-prone sites in normal valve and vessel wall. Methods The porcine aortic valve and renal artery ostial diverter, initiation sites of calcific valve disease and renal atherosclerosis, respectively, from normal non-diseased animals were used as models in these studies. Results Fluorescent human LDL was selectively retained on the lesion-prone collagen/proteoglycan-enriched aortic surface of the valve, where the elastic lamina is depleted, as previously observed in lesion-prone sites in the renal ostium. iTRAQ mass spectrometry of valve and diverter protein extracts identified decorin and biglycan as the major subendothelial intimal matrix proteoglycans electrostatically retained on human LDL affinity columns. Decorin levels correlated with LDL binding in lesion-prone sites in both tissues. Collagen binding to LDL was shown to be proteoglycan-mediated. All known basement membrane proteoglycans bound LDL suggesting they may modulate LDL uptake into the subendothelial matrix. The association of purified decorin with human LDL in an in vitro microassay was blocked by serum albumin and heparin suggesting anti-atherogenic roles for these proteins in vivo. Conclusions LDL electrostatic interactions with decorin and biglycan in the valve leaflets and vascular wall is a major source of LDL retention. The complementary electrostatic sites on LDL or these proteoglycans may provide a novel therapeutic target for preventing one of the earliest events in these cardiovascular diseases. PMID:24529131

Effects of landscape matrix on population connectivity of an arboreal mammal, Petaurus breviceps.

PubMed

Malekian, Mansoureh; Cooper, Steven J B; Saint, Kathleen M; Lancaster, Melanie L; Taylor, Andrea C; Carthew, Susan M

2015-09-01

Ongoing habitat loss and fragmentation is considered a threat to biodiversity as it can create small, isolated populations that are at increased risk of extinction. Tree-dependent species are predicted to be highly sensitive to forest and woodland loss and fragmentation, but few studies have tested the influence of different types of landscape matrix on gene flow and population structure of arboreal species. Here, we examine the effects of landscape matrix on population structure of the sugar glider (Petaurus breviceps) in a fragmented landscape in southeastern South Australia. We collected 250 individuals across 12 native Eucalyptus forest remnants surrounded by cleared agricultural land or exotic Pinus radiata plantations and a large continuous eucalypt forest. Fifteen microsatellite loci were genotyped and analyzed to infer levels of population differentiation and dispersal. Genetic differentiation among most forest patches was evident. We found evidence for female philopatry and restricted dispersal distances for females relative to males, suggesting there is male-biased dispersal. Among the environmental variables, spatial variables including geographic location, minimum distance to neighboring patch, and degree of isolation were the most important in explaining genetic variation. The permeability of a cleared agricultural matrix to dispersing gliders was significantly higher than that of a pine matrix, with the gliders dispersing shorter distances across the latter. Our results added to previous findings for other species of restricted dispersal and connectivity due to habitat fragmentation in the same region, providing valuable information for the development of strategies to improve the connectivity of populations in the future.

Coherent Activity in Bilateral Parieto-Occipital Cortices during P300-BCI Operation.

PubMed

Takano, Kouji; Ora, Hiroki; Sekihara, Kensuke; Iwaki, Sunao; Kansaku, Kenji

2014-01-01

The visual P300 brain-computer interface (BCI), a popular system for electroencephalography (EEG)-based BCI, uses the P300 event-related potential to select an icon arranged in a flicker matrix. In earlier studies, we used green/blue (GB) luminance and chromatic changes in the P300-BCI system and reported that this luminance and chromatic flicker matrix was associated with better performance and greater subject comfort compared with the conventional white/gray (WG) luminance flicker matrix. To highlight areas involved in improved P300-BCI performance, we used simultaneous EEG-fMRI recordings and showed enhanced activities in bilateral and right lateralized parieto-occipital areas. Here, to capture coherent activities of the areas during P300-BCI, we collected whole-head 306-channel magnetoencephalography data. When comparing functional connectivity between the right and left parieto-occipital channels, significantly greater functional connectivity in the alpha band was observed under the GB flicker matrix condition than under the WG flicker matrix condition. Current sources were estimated with a narrow-band adaptive spatial filter, and mean imaginary coherence was computed in the alpha band. Significantly greater coherence was observed in the right posterior parietal cortex under the GB than under the WG condition. Re-analysis of previous EEG-based P300-BCI data showed significant correlations between the power of the coherence of the bilateral parieto-occipital cortices and their performance accuracy. These results suggest that coherent activity in the bilateral parieto-occipital cortices plays a significant role in effectively driving the P300-BCI.

Effect of Botulinum Toxin Type A on TGF-β/Smad Pathway Signaling: Implications for Silicone-Induced Capsule Formation.

PubMed

Kim, Sena; Ahn, Moonsang; Piao, Yibo; Ha, Yooseok; Choi, Dae-Kyoung; Yi, Min-Hee; Shin, Nara; Kim, Dong Woon; Oh, Sang-Ha

2016-11-01

One of the most serious complications of breast surgery using implants is capsular contracture. Several preventive treatments have been introduced; however, the mechanism of capsule formation has not been resolved completely. The authors previously identified negative effects of botulinum toxin type A on capsule formation, expression of transforming growth factor (TGF)-β1, and differentiation of fibroblasts into myofibroblasts. Thus, the authors investigated how to prevent capsule formation by using botulinum toxin type A, particularly by means of TGF-β1 signaling, in human fibroblasts. In vitro, cultured human fibroblasts were treated with TGF-β1 and/or botulinum toxin type A. Expression of collagen, matrix metalloproteinase, and Smad was examined by Western blotting. The activation of matrix metalloproteinase was observed by gelatin zymography. In vivo, the effect of botulinum toxin type A on the phosphorylation of Smad2 in silicone-induced capsule formation was evaluated by immunocytochemistry. In vitro, the phosphorylation of Smad2 was inhibited by botulinum toxin type A treatment. The expression levels of collagen types 1 and 3 were inhibited by botulinum toxin type A treatment, whereas those of matrix metalloproteinase-2 and matrix metalloproteinase-9 were enhanced. Gelatin zymography experiments confirmed enhanced matrix metalloproteinase-2 activity in collagen degradation. In vivo, botulinum toxin type A treatment reduced capsule thickness and Smad2 phosphorylation in silicone-induced capsules. This study suggests that botulinum toxin type A plays an important role in the inhibition of capsule formation through the TGF-β/Smad signaling pathway. Therapeutic, V.

On the equilibrium state of a small system with random matrix coupling to its environment

NASA Astrophysics Data System (ADS)

Lebowitz, J. L.; Pastur, L.

2015-07-01

We consider a random matrix model of interaction between a small n-level system, S, and its environment, a N-level heat reservoir, R. The interaction between S and R is modeled by a tensor product of a fixed n× n matrix and a N× N Hermitian random matrix. We show that under certain ‘macroscopicity’ conditions on R, the reduced density matrix of the system {{ρ }S}=T{{r}R}ρ S\\cup R(eq), is given by ρ S(c)˜ exp \\{-β {{H}S}\\}, where HS is the Hamiltonian of the isolated system. This holds for all strengths of the interaction and thus gives some justification for using ρ S(c) to describe some nano-systems, like biopolymers, in equilibrium with their environment (Seifert 2012 Rep. Prog. Phys. 75 126001). Our results extend those obtained previously in (Lebowitz and Pastur 2004 J. Phys. A: Math. Gen. 37 1517-34) (Lebowitz et al 2007 Contemporary Mathematics (Providence RI: American Mathematical Society) pp 199-218) for a special two-level system.

Analysis of the release process of phenylpropanolamine hydrochloride from ethylcellulose matrix granules IV.(1)) Evaluation of the controlled release properties for in vivo and in vitro release systems.

PubMed

Fukui, Atsuko; Fujii, Ryuta; Yonezawa, Yorinobu; Sunada, Hisakazu

2007-11-01

In the pharmaceutical preparation of a controlled release drug, it is very important and necessary to understand the release properties. The dissolution test is a very important and useful method for understanding and predicting drug-release properties. It was readily confirmed in the previous paper that the release process could be assessed quantitatively by a combination of the square-root time law and cube-root law equations for ethylcellulose (EC) matrix granules of phenylpropanolamine hydrochloride (PPA). In this paper EC layered granules were used in addition to EC matrix. The relationship between release property and the concentration of PPA in plasma after administration using beagle dogs were examined. Then it was confirmed that the correlativity for EC layered granules and EC matrix were similar each other. Therefore, it was considered that the dissolution test is useful for prediction of changes in concentration of PPA in the blood with time. And it was suggested that EC layered granules were suitable as a controlled release system as well as EC matrix.

Cellulose biosynthesis by the beta-proteobacterium, Chromobacterium violaceum.

PubMed

Recouvreux, Derce O S; Carminatti, Claudimir A; Pitlovanciv, Ana K; Rambo, Carlos R; Porto, Luismar M; Antônio, Regina V

2008-11-01

The Chromobacterium violaceum ATCC 12472 genome was sequenced by The Brazilian National Genome Project Consortium. Previous annotation reported the presence of cellulose biosynthesis genes in that genome. Analysis of these genes showed that, as observed in other bacteria, they are organized in two operons. In the present work, experimental evidences of the presence of cellulose in the extracellular matrix of the biofilm produced by C. violaceum in static cultures are shown. Biofilm samples were enzymatically digested by cellulase, releasing glucose units, suggesting the presence of cellulose as an extracellular matrix component. Fluorescence microscopy observations showed that C. violaceum produces a cellulase-sensitive extracellular matrix composed of fibers able to bind calcofluor. C. violaceum grows on medium containing Congo red, forming brown-red colonies. Together, these results suggest that cellulase-susceptible matrix material is cellulose. Scanning electronic microscopy analysis showed that the extracellular matrix exhibited a network of microfibrils, typical of bacterial cellulose. Although cellulose production is widely distributed between several bacterial species, including at least the groups of Gram-negative proteobacteria alpha and gamma, we give for the first time experimental evidence for cellulose production in beta-proteobacteria.

The matrix peptide exporter HAF-1 signals a mitochondrial unfolded protein response by activating the transcription factor ZC376.7 in C. elegans

PubMed Central

Haynes, Cole M.; Yang, Yun; Blais, Steven P.; Neubert, Thomas A.; Ron, David

2010-01-01

Summary Genetic analyses previously implicated the matrix-localized protease ClpP in signaling the stress of protein misfolding in the mitochondrial matrix to activate nuclear encoded mitochondrial chaperone genes in C. elegans (UPRmt). Here we report that haf-1, a gene encoding a mitochondria-localized ATP-binding cassette protein, is required for signaling within the UPRmt and for coping with misfolded protein stress. Peptide efflux from isolated mitochondria was ATP-dependent and required HAF-1 and the protease ClpP. Defective UPRmt signaling in the haf-1 deleted worms was associated with failure of the bZIP protein, ZC376.7, to localize to nuclei in worms with perturbed mitochondrial protein folding, whereas zc376.7(RNAi) strongly inhibited the UPRmt. These observations suggest a simple model whereby perturbation of the protein-folding environment in the mitochondrial matrix promotes ClpP-mediated generation of peptides whose haf-1-dependent export from the matrix contributes to UPRmt signaling across the mitochondrial inner membrane. PMID:20188671

Improved full analytical polygon-based method using Fourier analysis of the three-dimensional affine transformation.

PubMed

Pan, Yijie; Wang, Yongtian; Liu, Juan; Li, Xin; Jia, Jia

2014-03-01

Previous research [Appl. Opt.52, A290 (2013)] has revealed that Fourier analysis of three-dimensional affine transformation theory can be used to improve the computation speed of the traditional polygon-based method. In this paper, we continue our research and propose an improved full analytical polygon-based method developed upon this theory. Vertex vectors of primitive and arbitrary triangles and the pseudo-inverse matrix were used to obtain an affine transformation matrix representing the spatial relationship between the two triangles. With this relationship and the primitive spectrum, we analytically obtained the spectrum of the arbitrary triangle. This algorithm discards low-level angular dependent computations. In order to add diffusive reflection to each arbitrary surface, we also propose a whole matrix computation approach that takes advantage of the affine transformation matrix and uses matrix multiplication to calculate shifting parameters of similar sub-polygons. The proposed method improves hologram computation speed for the conventional full analytical approach. Optical experimental results are demonstrated which prove that the proposed method can effectively reconstruct three-dimensional scenes.

Genetic polymorphism of matrix metalloproteinase family and chronic obstructive pulmonary disease susceptibility: a meta-analysis.

PubMed

Zhou, Hongbin; Wu, Yinfang; Jin, Yan; Zhou, Jiesen; Zhang, Chao; Che, Luanqing; Jing, Jiyong; Chen, Zhihua; Li, Wen; Shen, Huahao

2013-10-02

Matrix metalloproteinase (MMP) family is considered to be associated with chronic obstructive pulmonary disease (COPD) pathogenesis, however, no consistent results have been provided by previous studies. In this report, we performed Meta analysis to investigate the association between four kinds of MMP single nucleotide polymorphisms (SNP, MMP1 -1607 1G/2G, MMP3 -1171 5A/6A, MMP9 -1562 C/T, MMP12 -82 A/G) and COPD risk from 21 studies including 4184 cases and 5716 controls. Both overall and subgroup association between SNP and COPD susceptibility were tested. There was no evident association between MMP polymorphisms and COPD susceptibility in general population. On the other hand, subgroup analysis suggested that MMP9 -1562 C/T polymorphism was related to COPD, as we found that C allele carriers were at lower risk in some subgroups stratified by lung function, age and genotype identification method, compared with TT homozygotes. Our results indicated the genotype TT might be one genetic risk factor of severe COPD.

Chaotic, informational and synchronous behaviour of multiplex networks

NASA Astrophysics Data System (ADS)

Baptista, M. S.; Szmoski, R. M.; Pereira, R. F.; Pinto, S. E. De Souza

2016-03-01

The understanding of the relationship between topology and behaviour in interconnected networks would allow to charac- terise and predict behaviour in many real complex networks since both are usually not simultaneously known. Most previous studies have focused on the relationship between topology and synchronisation. In this work, we provide analytical formulas that shows how topology drives complex behaviour: chaos, information, and weak or strong synchronisation; in multiplex net- works with constant Jacobian. We also study this relationship numerically in multiplex networks of Hindmarsh-Rose neurons. Whereas behaviour in the analytically tractable network is a direct but not trivial consequence of the spectra of eigenvalues of the Laplacian matrix, where behaviour may strongly depend on the break of symmetry in the topology of interconnections, in Hindmarsh-Rose neural networks the nonlinear nature of the chemical synapses breaks the elegant mathematical connec- tion between the spectra of eigenvalues of the Laplacian matrix and the behaviour of the network, creating networks whose behaviour strongly depends on the nature (chemical or electrical) of the inter synapses.

A Limited Comparison of the Thermal Durability of Polyimide Candidate Matrix Polymers with PMR-15

NASA Technical Reports Server (NTRS)

Bowles, Kenneth J.; Papadopoulos, Demetrios S.; Scheiman, Daniel A.; Inghram, Linda L.; McCorkle, Linda S.; Klans, Ojars V.

2003-01-01

Studies were conducted with six different candidate high-temperature neat matrix resin specimens of varied geometric shapes to investigate the mechanisms involved in the thermal degradation of polyimides like PMR-15. The metrics for assessing the quality of these candidates were chosen to be glass transition temperature (T(sub g)), thermo-oxidative stability, dynamic mechanical properties, microstructural changes, and dimensional stability. The processing and mechanical properties were not investigated in the study reported herein. The dimensional changes and surface layer growth were measured and recorded. The data were in agreement with earlier published data. An initial weight increase reaction was observed to be dominating at the lower temperatures. However, at the more elevated temperatures, the weight loss reactions were prevalent and probably masked the weight gain reaction. These data confirmed the findings of the existence of an initial weight gain reaction previously reported. Surface- and core-dependent weight losses were shown to control the polymer degradation at the higher temperatures.

Complex Langevin analysis of the spontaneous symmetry breaking in dimensionally reduced super Yang-Mills models

NASA Astrophysics Data System (ADS)

Anagnostopoulos, Konstantinos N.; Azuma, Takehiro; Ito, Yuta; Nishimura, Jun; Papadoudis, Stratos Kovalkov

2018-02-01

In recent years the complex Langevin method (CLM) has proven a powerful method in studying statistical systems which suffer from the sign problem. Here we show that it can also be applied to an important problem concerning why we live in four-dimensional spacetime. Our target system is the type IIB matrix model, which is conjectured to be a nonperturbative definition of type IIB superstring theory in ten dimensions. The fermion determinant of the model becomes complex upon Euclideanization, which causes a severe sign problem in its Monte Carlo studies. It is speculated that the phase of the fermion determinant actually induces the spontaneous breaking of the SO(10) rotational symmetry, which has direct consequences on the aforementioned question. In this paper, we apply the CLM to the 6D version of the type IIB matrix model and show clear evidence that the SO(6) symmetry is broken down to SO(3). Our results are consistent with those obtained previously by the Gaussian expansion method.

The electronic structure of VO in its ground and electronically excited states: A combined matrix isolation and quantum chemical (MRCI) study

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

Hübner, Olaf; Hornung, Julius; Himmel, Hans-Jörg, E-mail: hans-jorg.himmel@aci.uni-heidelberg.de

2015-07-14

The electronic ground and excited states of the vanadium monoxide (VO) molecule were studied in detail. Electronic absorption spectra for the molecule isolated in Ne matrices complement the previous gas-phase spectra. A thorough quantum chemical (multi-reference configuration interaction) study essentially confirms the assignment and characterization of the electronic excitations observed for VO in the gas-phase and in Ne matrices and allows the clarification of open issues. It provides a complete overview over the electronically excited states up to about 3 eV of this archetypical compound.

Enhancement of matrix metalloproteinases 2 and 9 accompanied with neurogenesis following collagen glycosaminoglycan matrix implantation after surgical brain injury.

PubMed

Hsu, Wei-Cherng; Yu, Chun-Hsien; Kung, Woon-Man; Huang, Kuo-Feng

2018-06-01

Surgical brain injury may result in irreversible neurological deficits. Our previous report showed that partial regeneration of a traumatic brain lesion is achieved by implantation of collagen glycosaminoglycan (CGM). Matrix metalloproteinases (MMPs) may play an important role in neurogenesis but there is currently a lack of studies displaying the relationship between the stimulation of MMPs and neurogenesis after collagen glycosaminoglycan implantation following surgical brain trauma. The present study was carried out to further examine the expression of MMP2 and MMP9 after implantation of collagen glycosaminoglycan (CGM) following surgical brain trauma. Using the animal model of surgically induced brain lesion, we implanted CGM into the surgical trauma. Rats were thus divided into three groups: (1) sham operation group: craniotomy only; (2) lesion (L) group: craniotomy + surgical trauma lesion; (3) lesion + CGM (L + CGM) group: CGM implanted following craniotomy and surgical trauma lesion. Cells positive for SOX2 (marker of proliferating neural progenitor cells) and matrix metalloproteinases (MMP2 and MMP9) in the lesion boundary zone were assayed and analyzed by immunofluorescence and ELISA commercial kits, respectively. Our results demonstrated that following implantation of CGM after surgical brain trauma, significant increases in MMP2 + /SOX2 + cells and MMP9 + /SOX2 + cells were seen within the lesion boundary zone in the L + CGM group. Tissue protein concentrations of MMP2 and MMP9 also increased after CGM scaffold implantation. These findings suggest that implantation of a CGM scaffold alone after surgical brain trauma can enhance the expression of MMP2 and MMP9 accompanied by neurogenesis.

Direct Comparison of Physical Properties of Bacillus subtilis NCIB 3610 and B-1 Biofilms

PubMed Central

Kesel, Sara; Grumbein, Stefan; Gümperlein, Ina; Tallawi, Marwa; Marel, Anna-Kristina

2016-01-01

Many bacteria form surface-attached communities known as biofilms. Due to the extreme resistance of these bacterial biofilms to antibiotics and mechanical stresses, biofilms are of growing interest not only in microbiology but also in medicine and industry. Previous studies have determined the extracellular polymeric substances present in the matrix of biofilms formed by Bacillus subtilis NCIB 3610. However, studies on the physical properties of biofilms formed by this strain are just emerging. In particular, quantitative data on the contributions of biofilm matrix biopolymers to these physical properties are lacking. Here, we quantitatively investigated three physical properties of B. subtilis NCIB 3610 biofilms: the surface roughness and stiffness and the bulk viscoelasticity of these biofilms. We show how specific biomolecules constituting the biofilm matrix formed by this strain contribute to those biofilm properties. In particular, we demonstrate that the surface roughness and surface elasticity of 1-day-old NCIB 3610 biofilms are strongly affected by the surface layer protein BslA. For a second strain, B. subtilis B-1, which forms biofilms containing mainly γ-polyglutamate, we found significantly different physical biofilm properties that are also differently affected by the commonly used antibacterial agent ethanol. We show that B-1 biofilms are protected from ethanol-induced changes in the biofilm's stiffness and that this protective effect can be transferred to NCIB 3610 biofilms by the sole addition of γ-polyglutamate to growing NCIB 3610 biofilms. Together, our results demonstrate the importance of specific biofilm matrix components for the distinct physical properties of B. subtilis biofilms. PMID:26873313

Hierarchical spatial segregation of two Mediterranean vole species: the role of patch-network structure and matrix composition.

PubMed

Pita, Ricardo; Lambin, Xavier; Mira, António; Beja, Pedro

2016-09-01

According to ecological theory, the coexistence of competitors in patchy environments may be facilitated by hierarchical spatial segregation along axes of environmental variation, but empirical evidence is limited. Cabrera and water voles show a metapopulation-like structure in Mediterranean farmland, where they are known to segregate along space, habitat, and time axes within habitat patches. Here, we assess whether segregation also occurs among and within landscapes, and how this is influenced by patch-network and matrix composition. We surveyed 75 landscapes, each covering 78 ha, where we mapped all habitat patches potentially suitable for Cabrera and water voles, and the area effectively occupied by each species (extent of occupancy). The relatively large water vole tended to be the sole occupant of landscapes with high habitat amount but relatively low patch density (i.e., with a few large patches), and with a predominantly agricultural matrix, whereas landscapes with high patch density (i.e., many small patches) and low agricultural cover, tended to be occupied exclusively by the small Cabrera vole. The two species tended to co-occur in landscapes with intermediate patch-network and matrix characteristics, though their extents of occurrence were negatively correlated after controlling for environmental effects. In combination with our previous studies on the Cabrera-water vole system, these findings illustrated empirically the occurrence of hierarchical spatial segregation, ranging from within-patches to among-landscapes. Overall, our study suggests that recognizing the hierarchical nature of spatial segregation patterns and their major environmental drivers should enhance our understanding of species coexistence in patchy environments.

Potential Use of {sup 18}F-fluorodeoxyglucose Positron Emission Tomography–Based Quantitative Imaging Features for Guiding Dose Escalation in Stage III Non-Small Cell Lung Cancer

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

Fried, David V., E-mail: dvfried@mdanderson.org; Graduate School of Biomedical Sciences, The University of Texas MD Anderson Cancer Center, Houston, Texas; Mawlawi, Osama

2016-02-01

Purpose: To determine whether previously identified quantitative image features (QIFs) based on {sup 18}F-fluorodeoxyglucose positron emission tomography (FDG-PET) (co-occurrence matrix energy and solidity) are able to isolate subgroups of patients who would receive a benefit or detriment from dose escalation in terms of overall survival (OS) or progression-free survival (PFS). Methods and Materials: Subgroups of a previously analyzed 225 patient cohort were generated with the use of 5-percentile increment cutoff values of disease solidity and primary tumor co-occurrence matrix energy. The subgroups were analyzed with a log-rank test to determine whether there was a difference in OS and PFS betweenmore » patients treated with 60 to 70 Gy and those receiving 74 Gy. Results: In the entire patient cohort, there was no statistical difference in terms of OS or PFS between patients receiving 74 Gy and those receiving 60 to 70 Gy. It was qualitatively observed that as disease solidity and primary co-occurrence matrix energy increased, patients receiving 74 Gy had an improved OS and PFS compared with those receiving 60 to 70 Gy. The opposite trend (detriment of receiving 74 Gy) was also observed regarding low values of disease solidity and primary co-occurrence matrix energy. Conclusions: FDG-PET–based QIFs were found to be capable of isolating subgroups of patients who received a benefit or detriment from dose escalation.« less

An ESS maximum principle for matrix games.

PubMed

Vincent, T L; Cressman, R

2000-11-01

Previous work has demonstrated that for games defined by differential or difference equations with a continuum of strategies, there exists a G-function, related to individual fitness, that must take on a maximum with respect to a virtual variable v whenever v is one of the vectors in the coalition of vectors which make up the evolutionarily stable strategy (ESS). This result, called the ESS maximum principle, is quite useful in determining candidates for an ESS. This principle is reformulated here, so that it may be conveniently applied to matrix games. In particular, we define a matrix game to be one in which fitness is expressed in terms of strategy frequencies and a matrix of expected payoffs. It is shown that the G-function in the matrix game setting must again take on a maximum value at all the strategies which make up the ESS coalition vector. The reformulated maximum principle is applicable to both bilinear and nonlinear matrix games. One advantage in employing this principle to solve the traditional bilinear matrix game is that the same G-function is used to find both pure and mixed strategy solutions by simply specifying an appropriate strategy space. Furthermore we show how the theory may be used to solve matrix games which are not in the usual bilinear form. We examine in detail two nonlinear matrix games: the game between relatives and the sex ratio game. In both of these games an ESS solution is determined. These examples not only illustrate the usefulness of this approach to finding solutions to an expanded class of matrix games, but aids in understanding the nature of the ESS as well.

Key-Generation Algorithms for Linear Piece In Hand Matrix Method

NASA Astrophysics Data System (ADS)

Tadaki, Kohtaro; Tsujii, Shigeo

The linear Piece In Hand (PH, for short) matrix method with random variables was proposed in our former work. It is a general prescription which can be applicable to any type of multivariate public-key cryptosystems for the purpose of enhancing their security. Actually, we showed, in an experimental manner, that the linear PH matrix method with random variables can certainly enhance the security of HFE against the Gröbner basis attack, where HFE is one of the major variants of multivariate public-key cryptosystems. In 1998 Patarin, Goubin, and Courtois introduced the plus method as a general prescription which aims to enhance the security of any given MPKC, just like the linear PH matrix method with random variables. In this paper we prove the equivalence between the plus method and the primitive linear PH matrix method, which is introduced by our previous work to explain the notion of the PH matrix method in general in an illustrative manner and not for a practical use to enhance the security of any given MPKC. Based on this equivalence, we show that the linear PH matrix method with random variables has the substantial advantage over the plus method with respect to the security enhancement. In the linear PH matrix method with random variables, the three matrices, including the PH matrix, play a central role in the secret-key and public-key. In this paper, we clarify how to generate these matrices and thus present two probabilistic polynomial-time algorithms to generate these matrices. In particular, the second one has a concise form, and is obtained as a byproduct of the proof of the equivalence between the plus method and the primitive linear PH matrix method.

Enamel organic matrix: potential structural role in enamel and relationship to residual basement membrane constituents at the dentin enamel junction

PubMed Central

McGuire, Jacob D.; Walker, Mary P.; Dusevich, Vladimir; Wang, Yong; Gorski, Jeff P.

2015-01-01

Although mature enamel is predominantly composed of mineral, a previously uncharacterized organic matrix layer remains in the post-eruptive tissue that begins at the dentin enamel junction and extends 200–300 µm towards the outer tooth surface. Identification of the composition of this layer has been hampered by its insolubility; however, we have developed a single step method to isolate the organic enamel matrix relatively intact. After dissociative dissolution of the matrix with SDS and urea, initial characterization by Western blotting and gel zymography indicates the presence of type IV and type VII basement membrane collagens and active matrix metalloproteinase-20. When combined with data from transgenic knockout mice and from human mutations, these data suggest that the enamel organic matrix (EOM) and dentin enamel junction may have a structural and functional relationship with basement membranes, e.g. skin. To clarify this relationship, we hypothesize a “foundation” model which proposes that components of the EOM form a support structure that stabilizes the crystalline enamel layer, and bonds it to the underlying dentin along the dentin enamel junction. Since we have also co-localized an active matrix metalloproteinase to this layer, our hypothesis suggests that, under pathologic conditions, MMP-mediated degradation of the EOM could destabilize the enamel–dentin interface. PMID:25158177

Coherent Microwave Scattering Model of Marsh Grass

NASA Astrophysics Data System (ADS)

Duan, Xueyang; Jones, Cathleen E.

2017-12-01

In this work, we developed an electromagnetic scattering model to analyze radar scattering from tall-grass-covered lands such as wetlands and marshes. The model adopts the generalized iterative extended boundary condition method (GIEBCM) algorithm, previously developed for buried cylindrical media such as vegetation roots, to simulate the scattering from the grass layer. The major challenge of applying GIEBCM to tall grass is the extremely time-consuming iteration among the large number of short subcylinders building up the grass. To overcome this issue, we extended the GIEBCM to multilevel GIEBCM, or M-GIEBCM, in which we first use GIEBCM to calculate a T matrix (transition matrix) database of "straws" with various lengths, thicknesses, orientations, curvatures, and dielectric properties; we then construct the grass with a group of straws from the database and apply GIEBCM again to calculate the T matrix of the overall grass scene. The grass T matrix is transferred to S matrix (scattering matrix) and combined with the ground S matrix, which is computed using the stabilized extended boundary condition method, to obtain the total scattering. In this article, we will demonstrate the capability of the model by simulating scattering from scenes with different grass densities, different grass structures, different grass water contents, and different ground moisture contents. This model will help with radar experiment design and image interpretation for marshland and wetland observations.

Proteomic analysis of sea urchin (Strongylocentrotus purpuratus) spicule matrix

PubMed Central

2010-01-01

Background The sea urchin embryo has been an important model organism in developmental biology for more than a century. This is due to its relatively simple construction, translucent appearance, and the possibility to follow the fate of individual cells as development to the pluteus larva proceeds. Because the larvae contain tiny calcitic skeletal elements, the spicules, they are also important model organisms for biomineralization research. Similar to other biominerals the spicule contains an organic matrix, which is thought to play an important role in its formation. However, only few spicule matrix proteins were identified previously. Results Using mass spectrometry-based methods we have identified 231 proteins in the matrix of the S. purpuratus spicule matrix. Approximately two thirds of the identified proteins are either known or predicted to be extracellular proteins or transmembrane proteins with large ectodomains. The ectodomains may have been solubilized by partial proteolysis and subsequently integrated into the growing spicule. The most abundant protein of the spicule matrix is SM50. SM50-related proteins, SM30-related proteins, MSP130 and related proteins, matrix metalloproteases and carbonic anhydrase are among the most abundant components. Conclusions The spicule matrix is a relatively complex mixture of proteins not only containing matrix-specific proteins with a function in matrix assembly or mineralization, but also: 1) proteins possibly important for the formation of the continuous membrane delineating the mineralization space; 2) proteins for secretory processes delivering proteinaceous or non-proteinaceous precursors; 3) or proteins reflecting signaling events at the cell/matrix interface. Comparison of the proteomes of different skeletal matrices allows prediction of proteins of general importance for mineralization in sea urchins, such as SM50, SM30-E, SM29 or MSP130. The comparisons also help point out putative tissue-specific proteins, such as tooth phosphodontin or specific spicule matrix metalloproteases of the MMP18/19 group. Furthermore, the direct sequence analysis of peptides by MS/MS validates many predicted genes and confirms the existence of the corresponding proteins. PMID:20565753

Empathic control through coordinated interaction of amygdala, theory of mind and extended pain matrix brain regions.

PubMed

Bruneau, Emile G; Jacoby, Nir; Saxe, Rebecca

2015-07-01

Brain regions in the "pain matrix", can be activated by observing or reading about others in physical pain. In previous research, we found that reading stories about others' emotional suffering, by contrast, recruits a different group of brain regions mostly associated with thinking about others' minds. In the current study, we examined the neural circuits responsible for deliberately regulating empathic responses to others' pain and suffering. In Study 1, a sample of college-aged participants (n=18) read stories about physically painful and emotionally distressing events during functional magnetic resonance imaging (fMRI), while either actively empathizing with the main character or trying to remain objective. In Study 2, the same experiment was performed with professional social workers, who are chronically exposed to human suffering (n=21). Across both studies activity in the amygdala was associated with empathic regulation towards others' emotional pain, but not their physical pain. In addition, psychophysiological interaction (PPI) analysis and Granger causal modeling (GCM) showed that amygdala activity while reading about others' emotional pain was preceded by and positively coupled with activity in the theory of mind brain regions, and followed by and negatively coupled with activity in regions associated with physical pain and bodily sensations. Previous work has shown that the amygdala is critically involved in the deliberate control of self-focused distress - the current results extend the central importance of amygdala activity to the control of other-focused empathy, but only when considering others' emotional pain. Copyright © 2015 Elsevier Inc. All rights reserved.

Cell adhesion in zebrafish myogenesis: distribution of intermediate filaments, microfilaments, intracellular adhesion structures and extracellular matrix.

PubMed

Costa, Manoel L; Escaleira, Roberta C; Jazenko, Fernanda; Mermelstein, Claudia S

2008-10-01

To overcome the limitations of in vitro studies, we have been studying myogenesis in situ in zebrafish embryos, at a sub-cellular level. While in previous works we focused on myofibrillogenesis and some aspects of adhesion structures, here we describe in more detail cell adhesion structures and interactions among cytoskeletal components, membrane and extracellular matrix during zebrafish muscle development. We studied the intermediate filaments, and we describe the full range of desmin distribution in zebrafish development, from perinuclear to striated, until its deposition around the intersomite septa of older somites. This adhesion structure, positive for desmin and actin, has not been previously observed in myogenesis in vitro. We also show that actin is initially located in the intersomite septum region whereas it is confined to the myofibrils later on. While actin localization changes during development, the adhesion complex proteins vinculin, paxillin, talin, dystrophin, laminin and fibronectin always appear exclusively at the intersomite septa, and appear to be co-distributed, even though the extracellular proteins accumulates before the intracellular ones. Contrary to the adhesion proteins, that are continuously distributed, desmin and sarcomeric actin form triangular aggregates among the septa and the cytoskeleton. We studied the cytoskeletal linker plectin as well, and we show that it has a distribution similar to desmin and not to actin. We conclude that the in situ adhesion structures differ from their in vitro counterparts, and that the actual zebrafish embryo myogenesis is quite different than that which occurs in in vitro systems. Copyright 2008 Wiley-Liss, Inc.

Cell-mediated fibre recruitment drives extracellular matrix mechanosensing in engineered fibrillar microenvironments

NASA Astrophysics Data System (ADS)

Baker, Brendon M.; Trappmann, Britta; Wang, William Y.; Sakar, Mahmut S.; Kim, Iris L.; Shenoy, Vivek B.; Burdick, Jason A.; Chen, Christopher S.

2015-12-01

To investigate how cells sense stiffness in settings structurally similar to native extracellular matrices, we designed a synthetic fibrous material with tunable mechanics and user-defined architecture. In contrast to flat hydrogel surfaces, these fibrous materials recapitulated cell-matrix interactions observed with collagen matrices including stellate cell morphologies, cell-mediated realignment of fibres, and bulk contraction of the material. Increasing the stiffness of flat hydrogel surfaces induced mesenchymal stem cell spreading and proliferation; however, increasing fibre stiffness instead suppressed spreading and proliferation for certain network architectures. Lower fibre stiffness permitted active cellular forces to recruit nearby fibres, dynamically increasing ligand density at the cell surface and promoting the formation of focal adhesions and related signalling. These studies demonstrate a departure from the well-described relationship between material stiffness and spreading established with hydrogel surfaces, and introduce fibre recruitment as a previously undescribed mechanism by which cells probe and respond to mechanics in fibrillar matrices.

A novel three-stage distance-based consensus ranking method

NASA Astrophysics Data System (ADS)

Aghayi, Nazila; Tavana, Madjid

2018-05-01

In this study, we propose a three-stage weighted sum method for identifying the group ranks of alternatives. In the first stage, a rank matrix, similar to the cross-efficiency matrix, is obtained by computing the individual rank position of each alternative based on importance weights. In the second stage, a secondary goal is defined to limit the vector of weights since the vector of weights obtained in the first stage is not unique. Finally, in the third stage, the group rank position of alternatives is obtained based on a distance of individual rank positions. The third stage determines a consensus solution for the group so that the ranks obtained have a minimum distance from the ranks acquired by each alternative in the previous stage. A numerical example is presented to demonstrate the applicability and exhibit the efficacy of the proposed method and algorithms.

Ground states of linear rotor chains via the density matrix renormalization group

NASA Astrophysics Data System (ADS)

Iouchtchenko, Dmitri; Roy, Pierre-Nicholas

2018-04-01

In recent years, experimental techniques have enabled the creation of ultracold optical lattices of molecules and endofullerene peapod nanomolecular assemblies. It was previously suggested that the rotor model resulting from the placement of dipolar linear rotors in one-dimensional lattices at low temperature has a transition between ordered and disordered phases. We use the density matrix renormalization group (DMRG) to compute ground states of chains of up to 100 rotors and provide further evidence of the phase transition in the form of a diverging entanglement entropy. We also propose two methods and present some first steps toward rotational spectra of such molecular assemblies using DMRG. The present work showcases the power of DMRG in this new context of interacting molecular rotors and opens the door to the study of fundamental questions regarding criticality in systems with continuous degrees of freedom.

Equine-derived bone mineral matrix for maxillary sinus floor augmentation: a clinical, radiographic, histologic, and histomorphometric case series.

PubMed

Nevins, Myron; Heinemann, Friedhelm; Janke, Ulrich W; Lombardi, Teresa; Nisand, David; Rocchietta, Isabella; Santoro, Giacomo; Schupbach, Peter; Kim, David M

2013-01-01

The objective of this proof-of-principle multicenter case series was to examine the bone regenerative potential of a newly introduced equine-derived bone mineral matrix (Equimatrix) to provide human sinus augmentation for the purpose of implant placement in the posterior maxilla. There were 10 patients requiring 12 maxillary sinus augmentations enrolled in this study. Histologic results at 6 months demonstrated abundant amounts of vital new bone in intimate contact with residual graft particles. Active bridging between residual graft particles with newly regenerated bone was routinely observed in intact core specimens. A mean value of 23.4% vital bone formation was observed at 6 months. This compared favorably with previous results using xenografts to produce bone in the maxillary sinus for the purpose of dental implant placement. Both the qualitative and quantitative results of this case series suggest comparable bone regenerative results at 6 months to bovine-derived xenografts.

Comparative study of original recover and recover KL in separable non-negative matrix factorization for topic detection in Twitter

NASA Astrophysics Data System (ADS)

Prabandari, R. D.; Murfi, H.

2017-07-01

An increasing amount of information on social media such as Twitter requires an efficient way to find the topics so that the information can be well managed. One of an automated method for topic detection is separable non-negative matrix factorization (SNMF). SNMF assumes that each topic has at least one word that does not appear on other topics. This method uses the direct approach and gives polynomial-time complexity, while the previous methods are iterative approaches and have NP-hard complexity. There are three steps of SNMF algorithm, i.e. constructing word co-occurrences, finding anchor words, and recovering topics. In this paper, we examine two topic recover methods, namely original recover that is using algebraic manipulation and recover KL that using probability approach with Kullback-Leibler divergence. Our simulations show that recover KL provides better accuracies in term of topic recall than original recover.

Avoidance of stress corrosion susceptibility in high strength aluminum alloys by control of grain boundary and matrix microstructure

NASA Technical Reports Server (NTRS)

Adler, P.; Deiasi, R.

1974-01-01

The relation of microstructure to the mechanical strength and stress corrosion resistance of highest strength and overaged tempers of BAR and 7050 aluminum alloys was investigated. Comparison is made with previously studied 7075 aluminum alloy. Optical microscopy, transmission electron microscopy, and differential scanning calorimetry were used to characterize the grain morphology, matrix microstructure, and grain boundary microstructure of these tempers. Grain boundary interparticle spacing was significant to stress corrosion crack propagation for all three alloys; increasing interparticle spacing led to increased resistance to crack propagation. In addition, the fire grain size in Bar and 7050 appears to enhance crack propagation. The highest strength temper of 7050 has a comparatively high resistance to crack initiation. Overall stress corrosion behavior is dependent on environment pH, and evaluation over a range of pH is recommended.

Identification of observer/Kalman filter Markov parameters: Theory and experiments

NASA Technical Reports Server (NTRS)

Juang, Jer-Nan; Phan, Minh; Horta, Lucas G.; Longman, Richard W.

1991-01-01

An algorithm to compute Markov parameters of an observer or Kalman filter from experimental input and output data is discussed. The Markov parameters can then be used for identification of a state space representation, with associated Kalman gain or observer gain, for the purpose of controller design. The algorithm is a non-recursive matrix version of two recursive algorithms developed in previous works for different purposes. The relationship between these other algorithms is developed. The new matrix formulation here gives insight into the existence and uniqueness of solutions of certain equations and gives bounds on the proper choice of observer order. It is shown that if one uses data containing noise, and seeks the fastest possible deterministic observer, the deadbeat observer, one instead obtains the Kalman filter, which is the fastest possible observer in the stochastic environment. Results are demonstrated in numerical studies and in experiments on an ten-bay truss structure.

The sensitivity of direct identification from positive BacT/ALERT™ (bioMérieux) blood culture bottles by matrix-assisted laser desorption ionization time-of-flight mass spectrometry is low.

PubMed

Szabados, F; Michels, M; Kaase, M; Gatermann, S

2011-02-01

Recently, matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been presented as a novel method for the direct identification of bacteria from positive blood culture bottles. The rate of the MALDI TOF MS-based identification in the present study from positive BacT/ALERT (bioMérieux, Marcy l'Etoile, France) blood culture bottles was 30%, which is far below the previously reported sensitivities using the BACTEC (Becton Dickinson, Franklin Lakes, NJ, USA) system. We also found evidence that the Biotyper algorithm did not identify a second pathogen in cases of positive BacT/ALERT blood culture bottles containing two different species. © 2010 The Authors. Journal Compilation © 2010 European Society of Clinical Microbiology and Infectious Diseases.

Adhesion properties of Lactobacillus rhamnosus mucus-binding factor to mucin and extracellular matrix proteins.

PubMed

Nishiyama, Keita; Nakamata, Koichi; Ueno, Shintaro; Terao, Akari; Aryantini, Ni Putu Desy; Sujaya, I Nengah; Fukuda, Kenji; Urashima, Tadasu; Yamamoto, Yuji; Mukai, Takao

2015-01-01

We previously described potential probiotic Lactobacillus rhamnosus strains, isolated from fermented mare milk produced in Sumbawa Island, Indonesia, which showed high adhesion to porcine colonic mucin (PCM) and extracellular matrix (ECM) proteins. Recently, mucus-binding factor (MBF) was found in the GG strain of L. rhamnosus as a mucin-binding protein. In this study, we assessed the ability of recombinant MBF protein from the FSMM22 strain, one of the isolates of L. rhamnosus from fermented Sumbawa mare milk, to adhere to PCM and ECM proteins by overlay dot blot and Biacore assays. MBF bound to PCM, laminin, collagen IV, and fibronectin with submicromolar dissociation constants. Adhesion of the FSMM22 mbf mutant strain to PCM and ECM proteins was significantly less than that of the wild-type strain. Collectively, these results suggested that MBF contribute to L. rhamnosus host colonization via mucin and ECM protein binding.

EPS forces in Bacillus subtilis biofilms

NASA Astrophysics Data System (ADS)

Zhang, Wenbo; Angelini, Thomas; Tsai, Shih-Ming; Nixon, Ryan

2014-03-01

Bacteria have evolved to congregate in complex communities known as biofilms. The structure that holds a biofilm together is a matrix called extracellular polymeric substance (EPS). It has been observed in previous studies that EPS up-regulation occurs when the nutrient levels fall below a threshold concentration; this increase in EPS concentration produces an osmotic pressure that forces the colony to spread outward. This osmotic pressure may drive nutrient uptake, but the stresses generated by the EPS matrix has never been measured. Here we present measurements of the forces exerted by a biofilm on its supporting substrate and on its fluid nutrients. In our experiments, we use a technique analogous to traction force microscopy to measure strain in agar nutrient substrates imposed by Bacillus subtilis biofilms. By running additional test to measure the permeability and elastic modulus of the agar, we can estimate the pressure generated by the biofilm.

Drude weight of the spin-(1)/(2) XXZ chain: Density matrix renormalization group versus exact diagonalization

NASA Astrophysics Data System (ADS)

Karrasch, C.; Hauschild, J.; Langer, S.; Heidrich-Meisner, F.

2013-06-01

We revisit the problem of the spin Drude weight D of the integrable spin-1/2 XXZ chain using two complementary approaches, exact diagonalization (ED) and the time-dependent density-matrix renormalization group (tDMRG). We pursue two main goals. First, we present extensive results for the temperature dependence of D. By exploiting time translation invariance within tDMRG, one can extract D for significantly lower temperatures than in previous tDMRG studies. Second, we discuss the numerical quality of the tDMRG data and elaborate on details of the finite-size scaling of the ED results, comparing calculations carried out in the canonical and grand-canonical ensembles. Furthermore, we analyze the behavior of the Drude weight as the point with SU(2)-symmetric exchange is approached and discuss the relative contribution of the Drude weight to the sum rule as a function of temperature.

Amyloid fibers provide structural integrity to Bacillus subtilis biofilms.

PubMed

Romero, Diego; Aguilar, Claudio; Losick, Richard; Kolter, Roberto

2010-02-02

Bacillus subtilis forms biofilms whose constituent cells are held together by an extracellular matrix. Previous studies have shown that the protein TasA and an exopolysaccharide are the main components of the matrix. Given the importance of TasA in biofilm formation, we characterized the physicochemical properties of this protein. We report that purified TasA forms fibers of variable length and 10-15 nm in width. Biochemical analyses, in combination with the use of specific dyes and microscopic analyses, indicate that TasA forms amyloid fibers. Consistent with this hypothesis, TasA fibers required harsh treatments (e.g., formic acid) to be depolymerized. When added to a culture of a tasA mutant, purified TasA restored wild-type biofilm morphology, indicating that the purified protein retained biological activity. We propose that TasA forms amyloid fibers that bind cells together in the biofilm.

Enhancement of cooperation in the spatial prisoner's dilemma with a coherence-resonance effect through annealed randomness at a cooperator-defector boundary; comparison of two variant models

NASA Astrophysics Data System (ADS)

Tanimoto, Jun

2016-11-01

Inspired by the commonly observed real-world fact that people tend to behave in a somewhat random manner after facing interim equilibrium to break a stalemate situation whilst seeking a higher output, we established two models of the spatial prisoner's dilemma. One presumes that an agent commits action errors, while the other assumes that an agent refers to a payoff matrix with an added random noise instead of an original payoff matrix. A numerical simulation revealed that mechanisms based on the annealing of randomness due to either the action error or the payoff noise could significantly enhance the cooperation fraction. In this study, we explain the detailed enhancement mechanism behind the two models by referring to the concepts that we previously presented with respect to evolutionary dynamic processes under the names of enduring and expanding periods.

A Fast Gradient Method for Nonnegative Sparse Regression With Self-Dictionary

NASA Astrophysics Data System (ADS)

Gillis, Nicolas; Luce, Robert

2018-01-01

A nonnegative matrix factorization (NMF) can be computed efficiently under the separability assumption, which asserts that all the columns of the given input data matrix belong to the cone generated by a (small) subset of them. The provably most robust methods to identify these conic basis columns are based on nonnegative sparse regression and self dictionaries, and require the solution of large-scale convex optimization problems. In this paper we study a particular nonnegative sparse regression model with self dictionary. As opposed to previously proposed models, this model yields a smooth optimization problem where the sparsity is enforced through linear constraints. We show that the Euclidean projection on the polyhedron defined by these constraints can be computed efficiently, and propose a fast gradient method to solve our model. We compare our algorithm with several state-of-the-art methods on synthetic data sets and real-world hyperspectral images.

Process quality planning of quality function deployment for carrot syrup

NASA Astrophysics Data System (ADS)

Ekawati, Yurida; Noya, Sunday; Widjaja, Filemon

2017-06-01

Carrot products are rarely available in the market. Based on previous research that had been done using QFD to generate product design of carrots products, the research to produce the process quality planning had been carried out. The carrot product studied was carrot syrup. The research resulted in a process planning matrix for carrot syrup. The matrix gives information about critical process plan and the priority of the critical process plan. The critical process plan on the production process of carrot syrup consists of carrots sorting, carrots peeling, carrots washing, blanching process, carrots cutting, the making of pureed carrots, filtering carrot juice, the addition of sugar in carrot juice, the addition of food additives in carrot juice, syrup boiling, syrup filtering, syrup filling into the bottle, the bottle closure and cooling. The information will help the design of the production process of carrot syrup.

Snapshot Mueller polarimetry for biomedical diagnostic related to human liver fibrosis: evaluation of the method for biomedical assessments

NASA Astrophysics Data System (ADS)

Babilotte, P.; Dubreuil, M.; Rivet, S.; Lijour, Y.; Sevrain, D.; Martin, L.; Le Brun, G.; Le Grand, Y.; Le Jeune, B.

2011-10-01

Human liver biopsy samples, consisting into a 16 μm thickness biomaterial chemically fixed into a formaldehyde matrix, and stained by red picrosirius dye, are analysed for different states of fibrosis degeneration. Polarimetric methods, and specially Mueller polarimetry based on wavelength coding, have been qualified as an efficient tool to describe many different biological aspects. The polarimetric characteristics of the media, extracted from a Lu and Chipman decomposition1, 2 of their Mueller Matrix (MM), are correlated with the degeneracy level of tissue. Different works and results linked to the clinical analysis will be presented and compared to previous performed works.3 Polarimetric imaging will be presented and compared with SHG measurements. A statistical analysis of the distribution of polarimetric parameters (such as the retardance R and depolarisation Pd) will be presented too, in order to characterise the liver fibrosis level into the biomaterial under study.

Matrix metalloproteinase 9 (MMP-9) is indispensable for long term potentiation in the central and basal but not in the lateral nucleus of the amygdala.

PubMed

Gorkiewicz, Tomasz; Balcerzyk, Marcin; Kaczmarek, Leszek; Knapska, Ewelina

2015-01-01

It has been shown that matrix metalloproteinase 9 (MMP-9) is required for synaptic plasticity, learning and memory. In particular, MMP-9 involvement in long-term potentiation (LTP, the model of synaptic plasticity) in the hippocampus and prefrontal cortex has previously been demonstrated. Recent data suggest the role of MMP-9 in amygdala-dependent learning and memory. Nothing is known, however, about its physiological correlates in the specific pathways in the amygdala. In the present study we show that LTP in the basal and central but not lateral amygdala (LA) is affected by MMP-9 knock-out. The MMP-9 dependency of LTP was confirmed in brain slices treated with a specific MMP-9 inhibitor. The results suggest that MMP-9 plays different roles in synaptic plasticity in different nuclei of the amygdala.

Improved search for heavy neutrinos in the decay π → e ν

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

Aguilar-Arevalo, A.; Aoki, M.; Blecher, M.

In this study, a search for massive neutrinos has been made in the decay π + → e +ν. No evidence was found for extra peaks in the positron energy spectrum indicative of pion decays involving massive neutrinos (π → e +ν h). Upper limits (90 % C.L.) on the neutrino mixing matrix element |U ei| 2 in the neutrino mass region 60–135 MeV/c 2 were set, which are an order of magnitude improvement over previous results.

Improved search for heavy neutrinos in the decay π → e ν

DOE PAGES

Aguilar-Arevalo, A.; Aoki, M.; Blecher, M.; ...

2018-04-17

In this study, a search for massive neutrinos has been made in the decay π + → e +ν. No evidence was found for extra peaks in the positron energy spectrum indicative of pion decays involving massive neutrinos (π → e +ν h). Upper limits (90 % C.L.) on the neutrino mixing matrix element |U ei| 2 in the neutrino mass region 60–135 MeV/c 2 were set, which are an order of magnitude improvement over previous results.

Non-traditional applications of laser desorption/ionization mass spectrometry

NASA Astrophysics Data System (ADS)

McAlpin, Casey R.

Seven studies were carried out using laser desorption/ionization mass spectrometry (LDI MS) to develop enhanced methodologies for a variety of analyte systems by investigating analyte chemistries, ionization processes, and elimination of spectral interferences. Applications of LDI and matrix assisted laser/desorption/ionization (MALDI) have been previously limited by poorly understood ionization phenomena, and spectral interferences from matrices. Matrix assisted laser desorption ionization MS is well suited to the analysis of proteins. However, the proteins associated with bacteriophages often form complexes which are too massive for detection with a standard MALDI mass spectrometer. As such, methodologies for pretreatment of these samples are discussed in detail in the first chapter. Pretreatment of bacteriophage samples with reducing agents disrupted disulfide linkages and allowed enhanced detection of bacteriophage proteins. The second chapter focuses on the use of MALDI MS for lipid compounds whose molecular mass is significantly less than the proteins for which MALDI is most often applied. The use of MALDI MS for lipid analysis presented unique challenges such as matrix interference and differential ionization efficiencies. It was observed that optimization of the matrix system, and addition of cationization reagents mitigated these challenges and resulted in an enhanced methodology for MALDI MS of lipids. One of the challenges commonly encountered in efforts to expand MALDI MS applications is as previously mentioned interferences introduced by organic matrix molecules. The third chapter focuses on the development of a novel inorganic matrix replacement system called metal oxide laser ionization mass spectrometry (MOLI MS). In contrast to other matrix replacements, considerable effort was devoted to elucidating the ionization mechanism. It was shown that chemisorption of analytes to the metal oxide surface produced acidic adsorbed species which then protonated free analyte molecules. Expanded applications of MOLI MS were developed following description of the ionization mechanism. A series of experiments were carried out involving treatment of metal oxide surfaces with reagent molecules to expand MOLI MS and develop enhanced MOLI MS methodologies. It was found that treatment of the metal oxide surface with a small molecule to act as a proton source expanded MOLI MS to analytes which did not form acidic adsorbed species. Proton-source pretreated MOLI MS was then used for the analysis of oils obtained from the fast, anoxic pyrolysis of biomass (py-oil). These samples are complex and produce MOLI mass spectra with many peaks. In this experiment, methods of data reduction including Kendrick mass defects and nominal mass z*-scores, which are commonly used for the study of petroleum fractions, were used to interpret these spectra and identify the major constituencies of py-oils. Through data reduction and collision induced dissociation (CID), homologous series of compounds were rapidly identified. The final chapter involves using metal oxides to catalytically cleave the ester linkage on lipids containing fatty acids in addition to ionization. The cleavage process results in the production of spectra similar to those observed with saponification/methylation. Fatty acid profiles were generated for a variety of micro-organisms to differentiate between bacterial species. (Abstract shortened by UMI.)

Multi scale imaging of the Cloudy Zone in the Tazewell IIICD Meteorite

NASA Astrophysics Data System (ADS)

Einsle, J. F.; Harrison, R. J.; Nichols, C. I. O.; Blukis, R.; Midgley, P. A.; Eggeman, A.; Saghi, Z.; Bagot, P.

2015-12-01

Paleomagnetic studies of iron and stony iron meteorites suggest that many small planetary bodies possessed molten cores resulting in the generation of a magnetic field. As these bodies cooled, Fe-Ni metal trapped within their mantle underwent a series of low-temperature transitions, leading to the familiar Widmanstatten intergrowth of kamacite and taenite. Adjacent to the kamacite/taenite interface is the so-called "cloudy zone" (CZ): a nanoscale intergrowth of tetrataenite islands in an Fe-rich matrix phase formed via spinodal decomposition. It has recently been shown (Bryson et al. 2015, Nature) that the CZ encodes a time-series record of the evolution of the magnetic field generated by the molten core of the planetary body. Extracting meaningful paleomagnetic data from the CZ relies, on a thorough understanding of the 3D chemical and magnetic properties of the intergrowth focsusing on the interactions between the magnetically hard tetrataenite islands and the magnetically soft matrix. Here we present a multi scale study of the chemical and crystallographic make up of the CZ in the Tazewell IIICD meteorite, using a range of advanced microscopy techniques. The results provide unprecedented insight into the architecture of the CZ, with implications for how the CZ acquires chemical transformation remanance during cooling on the parent body. Previous 2D transmission electron microscope studies of the CZ suggested that the matrix is an ordered Fe3Ni phase with the L12 structure. Interpretation of the electron diffraction patterns and chemical maps in these studies was hindered by a failure to resolve signals from overlapping island and matrix phases. Here we obtain high resolution electron diffraction and 3D chemical maps with near atomic resolution using a combination of scanning precession electron diffraction, 3D STEM EDS and atom probe tomography. Using this combined methodology we reslove for the first time the phenomena of secondary precipitation in the tetrataenite islands and chemical partitioning of trace elements between the island and matrix phases. The new crystallographic and compositional measurements present a quantitative picture of low-temperature local equilibrium in the Fe-Ni system. This leads to an improved understanding of the magnetic models used to perform paleomagnetism of the CZ.

Sparse PCA with Oracle Property.

PubMed

Gu, Quanquan; Wang, Zhaoran; Liu, Han

In this paper, we study the estimation of the k -dimensional sparse principal subspace of covariance matrix Σ in the high-dimensional setting. We aim to recover the oracle principal subspace solution, i.e., the principal subspace estimator obtained assuming the true support is known a priori. To this end, we propose a family of estimators based on the semidefinite relaxation of sparse PCA with novel regularizations. In particular, under a weak assumption on the magnitude of the population projection matrix, one estimator within this family exactly recovers the true support with high probability, has exact rank- k , and attains a [Formula: see text] statistical rate of convergence with s being the subspace sparsity level and n the sample size. Compared to existing support recovery results for sparse PCA, our approach does not hinge on the spiked covariance model or the limited correlation condition. As a complement to the first estimator that enjoys the oracle property, we prove that, another estimator within the family achieves a sharper statistical rate of convergence than the standard semidefinite relaxation of sparse PCA, even when the previous assumption on the magnitude of the projection matrix is violated. We validate the theoretical results by numerical experiments on synthetic datasets.

Sparse PCA with Oracle Property

PubMed Central

Gu, Quanquan; Wang, Zhaoran; Liu, Han

2014-01-01

In this paper, we study the estimation of the k-dimensional sparse principal subspace of covariance matrix Σ in the high-dimensional setting. We aim to recover the oracle principal subspace solution, i.e., the principal subspace estimator obtained assuming the true support is known a priori. To this end, we propose a family of estimators based on the semidefinite relaxation of sparse PCA with novel regularizations. In particular, under a weak assumption on the magnitude of the population projection matrix, one estimator within this family exactly recovers the true support with high probability, has exact rank-k, and attains a s/n statistical rate of convergence with s being the subspace sparsity level and n the sample size. Compared to existing support recovery results for sparse PCA, our approach does not hinge on the spiked covariance model or the limited correlation condition. As a complement to the first estimator that enjoys the oracle property, we prove that, another estimator within the family achieves a sharper statistical rate of convergence than the standard semidefinite relaxation of sparse PCA, even when the previous assumption on the magnitude of the projection matrix is violated. We validate the theoretical results by numerical experiments on synthetic datasets. PMID:25684971

The optimal fiber volume fraction and fiber-matrix property compatibility in fiber reinforced composites

NASA Technical Reports Server (NTRS)

Pan, Ning

1992-01-01

Although the question of minimum or critical fiber volume fraction beyond which a composite can then be strengthened due to addition of fibers has been dealt with by several investigators for both continuous and short fiber composites, a study of maximum or optimal fiber volume fraction at which the composite reaches its highest strength has not been reported yet. The present analysis has investigated this issue for short fiber case based on the well-known shear lag (the elastic stress transfer) theory as the first step. Using the relationships obtained, the minimum spacing between fibers is determined upon which the maximum fiber volume fraction can be calculated, depending on the fiber packing forms within the composites. The effects on the value of this maximum fiber volume fraction due to such factors as fiber and matrix properties, fiber aspect ratio and fiber packing forms are discussed. Furthermore, combined with the previous analysis on the minimum fiber volume fraction, this maximum fiber volume fraction can be used to examine the property compatibility of fiber and matrix in forming a composite. This is deemed to be useful for composite design. Finally some examples are provided to illustrate the results.

Improving the Numerical Stability of Fast Matrix Multiplication

DOE PAGES

Ballard, Grey; Benson, Austin R.; Druinsky, Alex; ...

2016-10-04

Fast algorithms for matrix multiplication, namely those that perform asymptotically fewer scalar operations than the classical algorithm, have been considered primarily of theoretical interest. Apart from Strassen's original algorithm, few fast algorithms have been efficiently implemented or used in practical applications. However, there exist many practical alternatives to Strassen's algorithm with varying performance and numerical properties. Fast algorithms are known to be numerically stable, but because their error bounds are slightly weaker than the classical algorithm, they are not used even in cases where they provide a performance benefit. We argue in this study that the numerical sacrifice of fastmore » algorithms, particularly for the typical use cases of practical algorithms, is not prohibitive, and we explore ways to improve the accuracy both theoretically and empirically. The numerical accuracy of fast matrix multiplication depends on properties of the algorithm and of the input matrices, and we consider both contributions independently. We generalize and tighten previous error analyses of fast algorithms and compare their properties. We discuss algorithmic techniques for improving the error guarantees from two perspectives: manipulating the algorithms, and reducing input anomalies by various forms of diagonal scaling. In conclusion, we benchmark performance and demonstrate our improved numerical accuracy.« less

Optical absorption spectra of the uranium (4+) ion in the thorium germanate matrix

NASA Astrophysics Data System (ADS)

Gajek, Z.; Krupa, J. C.; Antic-Fidancev, E.

1997-01-01

Visible and infrared absorption measurements on the 0953-8984/9/2/023/img6 ion in tetragonal zircon-type matrix 0953-8984/9/2/023/img7 are reported and analysed in terms of the standard parametrization scheme. The observed 17 main peaks and a number of less intense lines have been assigned and fitted to most of the 32 allowed electric dipole transitions with the root mean square error equal to 0953-8984/9/2/023/img8. The free-ion parameters obtained for the model Hamiltonian, 0953-8984/9/2/023/img9, 0953-8984/9/2/023/img10, 0953-8984/9/2/023/img11 and 0953-8984/9/2/023/img12, as well as the corresponding crystal-field parameters, 0953-8984/9/2/023/img13, 0953-8984/9/2/023/img14, 0953-8984/9/2/023/img15, 0953-8984/9/2/023/img16 and 0953-8984/9/2/023/img17, agree fairly well with the initial theoretical estimations. The results are discussed in relation to the previous spectroscopic study on the scheelite-type matrix 0953-8984/9/2/023/img18.

Epimorphin expression in interstitial pneumonia

PubMed Central

Terasaki, Yasuhiro; Fukuda, Yuh; Suga, Moritaka; Ikeguchi, Naoki; Takeya, Motohiro

2005-01-01

Epimorphin modulates epithelial morphogenesis in embryonic mouse organs. We previously suggested that epimorphin contributes to repair of bleomycin-induced pulmonary fibrosis in mice via epithelium-mesenchyme interactions. To clarify the role of epimorphin in human lungs, we evaluated epimorphin expression and localization in normal lungs, lungs with nonspecific interstitial pneumonia (NSIP), and lungs with usual interstitial pneumonia (UIP); we also studied the effect of recombinant epimorphin on cultured human alveolar epithelial cells in vitro. Northern and Western blotting analyses revealed that epimorphin expression in NSIP samples were significantly higher than those in control lungs and lungs with UIP. Immunohistochemistry showed strong epimorphin expression in mesenchymal cells of early fibrotic lesions and localization of epimorphin protein on mesenchymal cells and extracellular matrix of early fibrotic lesions in the nonspecific interstitial pneumonia group. Double-labeled fluorescent images revealed expression of matrix metalloproteinase 2 in re-epithelialized cells overlying epimorphin-positive early fibrotic lesions. Immunohistochemistry and metalloproteinase activity assay demonstrated augmented expression of metalloproteinase induced by recombinant epimorphin in human alveolar epithelial cells. These findings suggest that epimorphin contributes to repair of pulmonary fibrosis in nonspecific interstitial pneumonia, perhaps partly by inducing expression of matrix metalloproteinase 2, which is an important proteolytic factor in lung remodeling. PMID:15651999

Investigation of solvent-free MALDI-TOFMS sample preparation methods for the analysis of organometallic and coordination compounds.

PubMed

Hughes, Laura; Wyatt, Mark F; Stein, Bridget K; Brenton, A Gareth

2009-01-15

An investigation of various solvent-free matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) sample preparation methods for the characterization of organometallic and coordination compounds is described. Such methods are desirable for insoluble materials, compounds that are only soluble in disadvantageous solvents, or complexes that dissociate in solution, all of which present a major "difficulty" to most mass spectrometry techniques. First-row transition metal acetylacetonate complexes, which have been characterized previously by solution preparation MALDI-TOFMS, were used to evaluate the various solvent-free procedures. These procedures comprise two distinct steps: the first being the efficient "solids mixing" (the mixing of sample and matrix), and the second being the effective transfer of the sample/matrix mixture to the MALDI target plate. This investigation shows that vortex mixing is the most efficient first step and that smearing using a microspatula is the most effective second step. In addition, the second step is shown to be much more critical than the first step in obtaining high-quality data. Case studies of truly insoluble materials highlight the importance of these techniques for the wider chemistry community.

Tumorigenic Potential of Extracellular Matrix Metalloproteinase Inducer

PubMed Central

Zucker, Stanley; Hymowitz, Michelle; Rollo, Ellen E.; Mann, Richard; Conner, Cathleen E.; Cao, Jian; Foda, Hussein D.; Tompkins, David C.; Toole, Bryan P.

2001-01-01

Extracellular matrix metalloproteinase inducer (EMMPRIN), a glycoprotein present on the cancer cell plasma membrane, enhances fibroblast synthesis of matrix metalloproteinases (MMPs). The demonstration that peritumoral fibroblasts synthesize most of the MMPs in human tumors rather than the cancer cells themselves has ignited interest in the role of EMMPRIN in tumor dissemination. In this report we have demonstrated a role for EMMPRIN in cancer progression. Human MDA-MB-436 breast cancer cells, which are tumorigenic but slow growing in vivo, were transfected with EMMPRIN cDNA and injected orthotopically into mammary tissue of female NCr nu/nu mice. Green fluorescent protein was used to visualize metastases. In three experiments, breast cancer cell clones transfected with EMMPRIN cDNA were considerably more tumorigenic and invasive than plasmid-transfected cancer cells. Increased gelatinase A and gelatinase B expression (demonstrated by in situ hybridization and gelatin substrate zymography) was demonstrated in EMMPRIN-enhanced tumors. In contrast to de novo breast cancers in humans, human tumors transplanted into mice elicited minimal stromal or inflammatory cell reactions. Based on these experimental studies and our previous demonstration that EMMPRIN is prominently displayed in human cancer tissue, we propose that EMMPRIN plays an important role in cancer progression by increasing synthesis of MMPs. PMID:11395366

miR-132 Regulates Dendritic Spine Structure by Direct Targeting of Matrix Metalloproteinase 9 mRNA.

PubMed

Jasińska, Magdalena; Miłek, Jacek; Cymerman, Iwona A; Łęski, Szymon; Kaczmarek, Leszek; Dziembowska, Magdalena

2016-09-01

Mir-132 is a neuronal activity-regulated microRNA that controls the morphology of dendritic spines and neuronal transmission. Similar activities have recently been attributed to matrix metalloproteinase-9 (MMP-9), an extrasynaptic protease. In the present study, we provide evidence that miR-132 directly regulates MMP-9 mRNA in neurons to modulate synaptic plasticity. With the use of luciferase reporter system, we show that miR-132 binds to the 3'UTR of MMP-9 mRNA to regulate its expression in neurons. The overexpression of miR-132 in neurons reduces the level of endogenous MMP-9 protein secretion. In synaptoneurosomes, metabotropic glutamate receptor (mGluR)-induced signaling stimulates the dissociation of miR-132 from polyribosomal fractions and shifts it towards the messenger ribonucleoprotein (mRNP)-containing fraction. Furthermore, we demonstrate that the overexpression of miR-132 in the cultured hippocampal neurons from Fmr1 KO mice that have increased synaptic MMP-9 level provokes enlargement of the dendritic spine heads, a process previously implicated in enhanced synaptic plasticity. We propose that activity-dependent miR-132 regulates structural plasticity of dendritic spines through matrix metalloproteinase 9.

Synthesis of linear regression coefficients by recovering the within-study covariance matrix from summary statistics.

PubMed

Yoneoka, Daisuke; Henmi, Masayuki

2017-06-01

Recently, the number of regression models has dramatically increased in several academic fields. However, within the context of meta-analysis, synthesis methods for such models have not been developed in a commensurate trend. One of the difficulties hindering the development is the disparity in sets of covariates among literature models. If the sets of covariates differ across models, interpretation of coefficients will differ, thereby making it difficult to synthesize them. Moreover, previous synthesis methods for regression models, such as multivariate meta-analysis, often have problems because covariance matrix of coefficients (i.e. within-study correlations) or individual patient data are not necessarily available. This study, therefore, proposes a brief explanation regarding a method to synthesize linear regression models under different covariate sets by using a generalized least squares method involving bias correction terms. Especially, we also propose an approach to recover (at most) threecorrelations of covariates, which is required for the calculation of the bias term without individual patient data. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

In-Situ Strain Analysis of Potential Habitat Composites Exposed to a Simulated Long-Term Lunar Radiation Exposure

NASA Technical Reports Server (NTRS)

Rojdev, Kristina; O'Rourke, Mary Jane; Hill, Charles; Nutt, Steven; Atwell, William

2010-01-01

NASA is studying the effects of long-term space radiation on potential multifunctional composite materials for habitats to better determine their characteristics in the harsh space environment. Two composite materials were selected for the study and were placed in a test stand that simulated the stresses of a pressure vessel wall on the material. The samples in the test stand were exposed to radiation at either a fast dose rate or a slow dose rate, and their strain and temperature was recorded during the exposure. It was found that during a fast dose rate exposure the materials saw a decreased strain with time, or a shrinking of the materials. Given previous radiation studies of polymers, this is believed to be a result of crosslinking occurring in the matrix material. However, with a slow dose rate, the materials saw an increase in strain with time, or a stretching of the materials. This result is consistent with scission or degradation of the matrix occurring, possibly due to oxidative degradation.

A Study on the Rectification Property of Self-Assembled Viologen Single Molecules Using a Scanning Tunneling Microscopy.

PubMed

Lee, Nam-Suk; Shin, Hoon-Kyu; Kwon, Young-Soo

2015-02-01

An ultrahigh vacuum scanning tunneling microscopy (UHV-STM) and a scanning tunneling spectroscopy (STS) are used measure the rectification property of self-assembled viologen single molecules (VC8SH, VC10SH, HSC8VC8SH, and HSC10VC10SH) in the previous study. Using STM we observe viologen single molecules in the self-assembled octanethiol (OT) SAM matrix. In the OT matrix a mixed phase that includes a c(4 x 2) superlattice of high-density standing up-phase is observed. We indicate high peak current-like rectifications at + 1.68 V(VC8SH), + 1.56 V(VC10SH), + 1.14 V(HSC8VC8SH), and + 1.04 V(HSC10VC10SH) based on the experiment implemented in this study. In addition, transition voltages (Vtrans) from direct tunneling to the Fowler-Nordheim tunneling are presented at 1.08 V(VC8SH), 0.97 V(VC10SH), 0.99 V(HSC8VC8SH), and 0.89 V(HSC1VC1SH).

Capillary electrophoresis coupled with electrochemiluminescence for determination of atomoxetine hydrochloride and the study on its interactions with three proteins.

PubMed

Zeng, Hua-jin; Yang, Ran; Zhang, Ying; Li, Jian-jun; Qu, Ling-bo

2015-03-01

A simple, rapid and sensitive method for the determination of atomoxetine hydrochloride (AH) by capillary electrophoresis with electrochemiluminescence detection (CE-ECL) using tris(2,2'-bipyridyl) ruthenium (II) was developed. Under optimized conditions, the determinations of AH in capsules and rat plasmas and the study on its interactions with three plasma proteins, including bovine serum albumin, cytochrome c and myoglobin were performed successfully. Relative to some previous studies, in this paper the methodologies for the determination of AH in aqueous solution and spiked plasma systems were established, respectively. By comparing the difference between the two work curves of two systems, the matrix effect in plasma samples on the determination of AH by the CE-ECL method was discussed in detail. The results indicated that the effect of the matrix in plasma samples should not be ignored even if no obvious interference was found in the electropherograms and the establishment of method validation in complex samples by the CE-ECL method was necessary. Copyright © 2014 John Wiley & Sons, Ltd.

A parametric study of fracture toughness of fibrous composite materials

NASA Technical Reports Server (NTRS)

Poe, C. C., Jr.

1987-01-01

Impacts to fibrous composite laminates by objects with low velocities can break fibers giving crack-like damage. The damage may not extend completely through a thick laminate. The tension strength of these damage laminates is reduced much like that of cracked metals. The fracture toughness depends on fiber and matrix properties, fiber orientations, and stacking sequence. Accordingly, a parametric study was made to determine how fiber and matrix properties and fiber orientations affect fracture toughness and notch sensitivity. The values of fracture toughness were predicted from the elastic constants of the laminate and the failing strain of the fibers using a general fracture toughness parameter developed previously. For a variety of laminates, values of fracture toughness from tests of center-cracked specimens and values of residual strength from tests of thick laminates with surface cracks were compared to the predictions to give credibility to the study. In contrast to the usual behavior of metals, it is shown that both ultimate tensile strength and fracture toughness of composites can be increased without increasing notch sensitivity.

Deducing Wild 2 Components with a Statistical Dataset of Olivine in Chondrite Matrix

NASA Technical Reports Server (NTRS)

Frank, D. R.; Zolensky, M. E.; Le, L.

2012-01-01

Introduction: A preliminary exam of the Wild 2 olivine yielded a major element distribution that is strikingly similar to those for aqueously altered carbonaceous chondrites (CI, CM, and CR) [1], in which FeO-rich olivine is preferentially altered. With evidence lacking for large-scale alteration in Wild 2, the mechanism for this apparent selectivity is poorly understood. We use a statistical approach to explain this distribution in terms of relative contributions from different chondrite forming regions. Samples and Analyses: We have made a particular effort to obtain the best possible analyses of both major and minor elements in Wild 2 olivine and the 5-30 micrometer population in chondrite matrix. Previous studies of chondrite matrix either include larger isolated grains (not found in the Wild 2 collection) or lack minor element abundances. To overcome this gap in the existing data, we have now compiled greater than 10(exp 3) EPMA analyses of matrix olivine in CI, CM, CR, CH, Kakangari, C2-ungrouped, and the least equilibrated CO, CV, LL, and EH chondrites. Also, we are acquiring TEM/EDXS analyses of the Wild 2 olivine with 500s count times, to reduce relative errors of minor elements with respect to those otherwise available. Results: Using our Wild 2 analyses and those from [2], the revised major element distribution is more similar to anhydrous IDPs than previous results, which were based on more limited statistics (see figure below). However, a large frequency peak at Fa(sub 0-1) still persists. All but one of these grains has no detectable Cr, which is dissimilar to the Fa(sub 0-1) found in the CI and CM matrices. In fact, Fa(sub 0-1) with strongly depleted Cr content is a composition that appears to be unique to Kakangari and enstatite (highly reduced) chondrites. We also note the paucity of Fa(sub greater than 58), which would typically indicate crystallization in a more oxidizing environment [3]. We conclude that, relative to the bulk of anhydrous IDPs, Wild 2 may have received a larger contribution from the Kakangari and/or enstatite chondrite forming regions. Alternatively, Wild 2 may have undergone accretion in an anomalously reducing region, marked by nebular condensation of this atypical forsterite. In [4], a similar conclusion was reached with an Fe-XANES study. We will also use similar lines of reasoning, and our previous conclusions in [5], to constrain the relative contributions of silicates that appear to have been radially transported from different ordinary and carbonaceous chondrite forming regions to the Kuiper Belt. In addition, the widespread depletion of Cr in these FeO-rich (Fa(sub greater than 20)) fragments is consistent with mild thermal metamorphism in Wild 2.

The influence of heterogeneous nucleation on the surface crystallization of guaifenesin from melt extrudates containing Eudragit L10055 or Acryl-EZE.

PubMed

Bruce, Caroline D; Fegely, Kurt A; Rajabi-Siahboomi, Ali R; McGinity, James W

2010-05-01

The objective of this study was to investigate the influence of talc and humidity conditions during storage on the crystal growth of guaifenesin on the surface of melt-extruded matrix tablets. Tablets consisted of the model drug guaifenesin in a matrix of either Acryl-EZE(R) or Eudragit(R) L10055 and either no talc, 25% or 50% talc. After processing, the hot-melt-extruded matrix tablets were supersaturated with amorphous guaifenesin, which resulted in the development of guaifenesin drug crystals on exposed surfaces of the tablet during storage (all tablets were stored at 24 degrees C). A previously developed, quantitative test was used to assay for surface guaifenesin. In tablets with a drug-to-polymer ratio of 19:81, talc-containing tablets exhibited an earlier onset of crystal growth (storage at 17% relative humidity). The presence of talc also increased the amount of surface crystallization and was independent of the talc concentration, since the talc levels used in this study exceeded the critical nucleant concentration. Additional non-melting components did not have an additive effect on surface crystal growth. High humidity during storage (78%) increased guaifenesin crystallization, but moisture uptake of tablets did not correlate with increased drug recrystallization. When storage at 17% relative humidity was interrupted for 3days by storage at 78% relative humidity before the tablets were returned to their previous low RH storage conditions, crystal growth quickly increased during the high RH interval and remained at an elevated level throughout the remaining storage period. A similar intermediate period of low, 17% relative humidity in tablets stored before and after that time at 78% RH did not affect surface crystallization levels. The effects of humidity and talc on the crystallization of guaifenesin from melt-extruded dosage forms supersaturated with amorphous drug were ascribed to heterogeneous nucleation.

Fibronectin matrix assembly is essential for cell condensation during chondrogenesis

PubMed Central

Singh, Purva; Schwarzbauer, Jean E.

2014-01-01

ABSTRACT Mesenchymal cell condensation is the initiating event in endochondral bone formation. Cell condensation is followed by differentiation into chondrocytes, which is accompanied by induction of chondrogenic gene expression. Gene mutations involved in chondrogenesis cause chondrodysplasias and other skeletal defects. Using mesenchymal stem cells (MSCs) in an in vitro chondrogenesis assay, we found that knockdown of the diastrophic dysplasia (DTD) sulfate transporter (DTDST, also known as SLC26A2), which is required for normal cartilage development, blocked cell condensation and caused a significant reduction in fibronectin matrix. Knockdown of fibronectin with small interfering RNAs (siRNAs) also blocked condensation. Fibrillar fibronectin matrix was detected prior to cell condensation, and its levels increased during and after condensation. Inhibition of fibronectin matrix assembly by use of the functional upstream domain (FUD) of adhesin F1 from Streptococcus pyogenes prevented cell condensation by MSCs and also by the chondrogenic cell line ATDC5. Our data show that cell condensation and induction of chondrogenesis depend on fibronectin matrix assembly and DTDST, and indicate that this transporter is required earlier in chondrogenesis than previously appreciated. They also raise the possibility that certain of the skeletal defects in DTD patients might derive from the link between DTDST, fibronectin matrix and condensation. PMID:25146392

Fibronectin matrix assembly is essential for cell condensation during chondrogenesis.

PubMed

Singh, Purva; Schwarzbauer, Jean E

2014-10-15

Mesenchymal cell condensation is the initiating event in endochondral bone formation. Cell condensation is followed by differentiation into chondrocytes, which is accompanied by induction of chondrogenic gene expression. Gene mutations involved in chondrogenesis cause chondrodysplasias and other skeletal defects. Using mesenchymal stem cells (MSCs) in an in vitro chondrogenesis assay, we found that knockdown of the diastrophic dysplasia (DTD) sulfate transporter (DTDST, also known as SLC26A2), which is required for normal cartilage development, blocked cell condensation and caused a significant reduction in fibronectin matrix. Knockdown of fibronectin with small interfering RNAs (siRNAs) also blocked condensation. Fibrillar fibronectin matrix was detected prior to cell condensation, and its levels increased during and after condensation. Inhibition of fibronectin matrix assembly by use of the functional upstream domain (FUD) of adhesin F1 from Streptococcus pyogenes prevented cell condensation by MSCs and also by the chondrogenic cell line ATDC5. Our data show that cell condensation and induction of chondrogenesis depend on fibronectin matrix assembly and DTDST, and indicate that this transporter is required earlier in chondrogenesis than previously appreciated. They also raise the possibility that certain of the skeletal defects in DTD patients might derive from the link between DTDST, fibronectin matrix and condensation. © 2014. Published by The Company of Biologists Ltd.

The kinesin KIF9 and reggie/flotillin proteins regulate matrix degradation by macrophage podosomes

PubMed Central

Cornfine, Susanne; Himmel, Mirko; Kopp, Petra; el Azzouzi, Karim; Wiesner, Christiane; Krüger, Marcus; Rudel, Thomas; Linder, Stefan

2011-01-01

Podosomes are actin-based matrix contacts in a variety of cell types, most notably monocytic cells, and are characterized by their ability to lyse extracellular matrix material. Besides their dependence on actin regulation, podosomes are also influenced by microtubules and microtubule-dependent transport processes. Here we describe a novel role for KIF9, a previously little-characterized member of the kinesin motor family, in the regulation of podosomes in primary human macrophages. We find that small interfering RNA (siRNA)/short-hairpin RNA–induced knockdown of KIF9 significantly affects both numbers and matrix degradation of podosomes. Overexpression and microinjection experiments reveal that the unique C-terminal region of KIF9 is crucial for these effects, presumably through binding of specific interactors. Indeed, we further identify reggie-1/flotillin-2, a signaling mediator between intracellular vesicles and the cell periphery, as an interactor of the KIF9 C-terminus. Reggie-1 dynamically colocalizes with KIF9 in living cells, and, consistent with KIF9-mediated effects, siRNA-induced knockdown of reggies/flotillins significantly impairs matrix degradation by podosomes. In sum, we identify the kinesin KIF9 and reggie/flotillin proteins as novel regulators of macrophage podosomes and show that their interaction is critical for the matrix-degrading ability of these structures. PMID:21119006

Analysis of solar spectra in the middle ultraviolet and visible for atmospheric trace constituents measurements. [hydroxyl radicals

NASA Technical Reports Server (NTRS)

Goldman, A.

1980-01-01

Individual spectral line parameters including line positions, strengths, and intensities were generated for the sq Alpha Sigma - sq Chi Pi (0,0) band of OH, applicable to atmospheric and high temperatures. Energy levels and transition frequencies are calculated by numerically diagonalizing the Hamiltonian. Line strengths are calculated using the dipole matrix and eigenvectors derived from energy matrix diagonalization. The line strengths are compared to those calculated from previously published algebraic line strength formulas. Tables of line parameters are presented for 240 K and 4600 K.

Stress as an order parameter for the glass transition

NASA Astrophysics Data System (ADS)

Visscher, P. B.; Logan, W. T.

1990-09-01

The stress tensor has been considered as a possible order parameter for the liquid-glass transition, and its autocorrelation matrix (elements of which are the integrands in the Green-Kubo formulas for bulk and shear viscosity) have been measured in simulations. However, only the k=0 spatial Fourier component has apparently been previously measured. We have measured four Fourier components of all matrix elements of the stress-stress correlation function, and we find that some of those with nonzero wave vector are significantly more persistent (slower decaying) than the k=0 component.

Electrostatic interactions and binding orientation of HIV-1 matrix studied by neutron reflectivity.

PubMed

Nanda, Hirsh; Datta, Siddhartha A K; Heinrich, Frank; Lösche, Mathias; Rein, Alan; Krueger, Susan; Curtis, Joseph E

2010-10-20

The N-terminal matrix (MA) domain of the HIV-1 Gag protein is responsible for binding to the plasma membrane of host cells during viral assembly. The putative membrane-binding interface of MA was previously mapped by means of mutagenesis and analysis of its trimeric crystal structure. However, the orientation of MA on membranes has not been directly determined by experimental measurements. We present neutron reflectivity measurements that resolve the one-dimensional scattering length density profile of MA bound to a biomimetic of the native viral membrane. A molecular refinement procedure was developed using atomic structures of MA to determine the orientation of the protein on the membrane. The orientation defines a lipid-binding interface consistent with previous mutagenesis results. The MA protein maintains this orientation without the presence of a myristate group, driven only by electrostatic interactions. Furthermore, MA is found to penetrate the membrane headgroup region peripherally such that only the side chains of specific Lys and Arg residues interact with the surface. The results suggest that electrostatic interactions are sufficient to favorably orient MA on viral membrane mimics. The spatial determination of the membrane-bound protein demonstrates the ability of neutron reflectivity to discern orientation and penetration under physiologically relevant conditions. Copyright © 2010 Biophysical Society. Published by Elsevier Inc. All rights reserved.

The pgaABCD Locus of Escherichia coli Promotes the Synthesis of a Polysaccharide Adhesin Required for Biofilm Formation

PubMed Central

Wang, Xin; Preston, James F.; Romeo, Tony

2004-01-01

Production of a polysaccharide matrix is a hallmark of bacterial biofilms, but the composition of matrix polysaccharides and their functions are not widely understood. Previous studies of the regulation of Escherichia coli biofilm formation suggested the involvement of an unknown adhesin. We now establish that the pgaABCD (formerly ycdSRQP) locus affects biofilm development by promoting abiotic surface binding and intercellular adhesion. All of the pga genes are required for optimal biofilm formation under a variety of growth conditions. A pga-dependent cell-bound polysaccharide was isolated and determined by nuclear magnetic resonance analyses to consist of unbranched β-1,6-N-acetyl-d-glucosamine, a polymer previously unknown from the gram-negative bacteria but involved in adhesion by staphylococci. The pga genes are predicted to encode envelope proteins involved in synthesis, translocation, and possibly surface docking of this polysaccharide. As predicted, if poly-β-1,6-GlcNAc (PGA) mediates cohesion, metaperiodate caused biofilm dispersal and the release of intact cells, whereas treatment with protease or other lytic enzymes had no effect. The pgaABCD operon exhibits features of a horizontally transferred locus and is present in a variety of eubacteria. Therefore, we propose that PGA serves as an adhesin that stabilizes biofilms of E. coli and other bacteria. PMID:15090514

Search for Majorana Neutrinos Near the Inverted Mass Hierarchy Region with KamLAND-Zen.

PubMed

Gando, A; Gando, Y; Hachiya, T; Hayashi, A; Hayashida, S; Ikeda, H; Inoue, K; Ishidoshiro, K; Karino, Y; Koga, M; Matsuda, S; Mitsui, T; Nakamura, K; Obara, S; Oura, T; Ozaki, H; Shimizu, I; Shirahata, Y; Shirai, J; Suzuki, A; Takai, T; Tamae, K; Teraoka, Y; Ueshima, K; Watanabe, H; Kozlov, A; Takemoto, Y; Yoshida, S; Fushimi, K; Banks, T I; Berger, B E; Fujikawa, B K; O'Donnell, T; Winslow, L A; Efremenko, Y; Karwowski, H J; Markoff, D M; Tornow, W; Detwiler, J A; Enomoto, S; Decowski, M P

2016-08-19

We present an improved search for neutrinoless double-beta (0νββ) decay of ^{136}Xe in the KamLAND-Zen experiment. Owing to purification of the xenon-loaded liquid scintillator, we achieved a significant reduction of the ^{110m}Ag contaminant identified in previous searches. Combining the results from the first and second phase, we obtain a lower limit for the 0νββ decay half-life of T_{1/2}^{0ν}>1.07×10^{26}  yr at 90% C.L., an almost sixfold improvement over previous limits. Using commonly adopted nuclear matrix element calculations, the corresponding upper limits on the effective Majorana neutrino mass are in the range 61-165 meV. For the most optimistic nuclear matrix elements, this limit reaches the bottom of the quasidegenerate neutrino mass region.

Search for Majorana Neutrinos Near the Inverted Mass Hierarchy Region with KamLAND-Zen

DOE PAGES

Gando, A.; Gando, Y.; Hachiya, T.; ...

2016-08-16

Here, we present an improved search for neutrinoless double-beta (0νββ) decay of Xe 136 in the KamLAND-Zen experiment. Owing to purification of the xenon-loaded liquid scintillator, we achieved a significant reduction of the Ag 110m contaminant identified in previous searches. Combining the results from the first and second phase, we obtain a lower limit for the 0νββ decay half-life of Tmore » $$0v\\atop{1/2}$$ > 1.07×10 26 yr at 90% C.L., an almost sixfold improvement over previous limits. Using commonly adopted nuclear matrix element calculations, the corresponding upper limits on the effective Majorana neutrino mass are in the range 61-165 meV. Finally, for the most optimistic nuclear matrix elements, this limit reaches the bottom of the quasidegenerate neutrino mass region.« less

A rapid and high-precision method for sulfur isotope δ(34)S determination with a multiple-collector inductively coupled plasma mass spectrometer: matrix effect correction and applications for water samples without chemical purification.

PubMed

Lin, An-Jun; Yang, Tao; Jiang, Shao-Yong

2014-04-15

Previous studies have indicated that prior chemical purification of samples, although complex and time-consuming, is essential in obtaining precise and accurate results for sulfur isotope ratios using multiple-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). In this study, we introduce a new, rapid and precise MC-ICP-MS method for sulfur isotope determination from water samples without chemical purification. The analytical work was performed on an MC-ICP-MS instrument with medium mass resolution (m/Δm ~ 3000). Standard-sample bracketing (SSB) was used to correct samples throughout the analytical sessions. Reference materials included an Alfa-S (ammonium sulfate) standard solution, ammonium sulfate provided by the lab of the authors and fresh seawater from the South China Sea. A range of matrix-matched Alfa-S standard solutions and ammonium sulfate solutions was used to investigate the matrix (salinity) effect (matrix was added in the form of NaCl). A seawater sample was used to confirm the reliability of the method. Using matrix-matched (salinity-matched) Alfa-S as the working standard, the measured δ(34)S value of AS (-6.73 ± 0.09‰) was consistent with the reference value (-6.78 ± 0.07‰) within the uncertainty, suggesting that this method could be recommended for the measurement of water samples without prior chemical purification. The δ(34)S value determination for the unpurified seawater also yielded excellent results (21.03 ± 0.18‰) that are consistent with the reference value (20.99‰), thus confirming the feasibility of the technique. The data and the results indicate that it is feasible to use MC-ICP-MS and matrix-matched working standards to measure the sulfur isotopic compositions of water samples directly without chemical purification. In comparison with the existing MC-ICP-MS techniques, the new method is better for directly measuring δ(34)S values in water samples with complex matrices; therefore, it can significantly accelerate analytical turnover. Copyright © 2014 John Wiley & Sons, Ltd.

Solidification processing of monotectic alloy matrix composites

NASA Technical Reports Server (NTRS)

Frier, Nancy L.; Shiohara, Yuh; Russell, Kenneth C.

1989-01-01

Directionally solidified aluminum-indium alloys of the monotectic composition were found to form an in situ rod composite which obeys a lambda exp 2 R = constant relation. The experimental data shows good agreement with previously reported results. A theoretical boundary between cellular and dendritic growth conditions was derived and compared with experiments. The unique wetting characteristics of the monotectic alloys can be utilized to tailor the interface structure in metal matrix composites. Metal matrix composites with monotectic and hypermonotectic Al-In matrices were made by pressure infiltration, remelted and directionally solidified to observe the wetting characteristics of the alloys as well as the effect on structure of solidification in the constrained field of the fiber interstices. Models for monotectic growth are modified to take into account solidification in these constrained fields.

On the origin of dual Lax pairs and their r-matrix structure

NASA Astrophysics Data System (ADS)

Avan, Jean; Caudrelier, Vincent

2017-10-01

We establish the algebraic origin of the following observations made previously by the authors and coworkers: (i) A given integrable PDE in 1 + 1 dimensions within the Zakharov-Shabat scheme related to a Lax pair can be cast in two distinct, dual Hamiltonian formulations; (ii) Associated to each formulation is a Poisson bracket and a phase space (which are not compatible in the sense of Magri); (iii) Each matrix in the Lax pair satisfies a linear Poisson algebra a la Sklyanin characterized by the same classical r matrix. We develop the general concept of dual Lax pairs and dual Hamiltonian formulation of an integrable field theory. We elucidate the origin of the common r-matrix structure by tracing it back to a single Lie-Poisson bracket on a suitable coadjoint orbit of the loop algebra sl(2 , C) ⊗ C(λ ,λ-1) . The results are illustrated with the examples of the nonlinear Schrödinger and Gerdjikov-Ivanov hierarchies.

Hypercube matrix computation task

NASA Technical Reports Server (NTRS)

Calalo, Ruel H.; Imbriale, William A.; Jacobi, Nathan; Liewer, Paulett C.; Lockhart, Thomas G.; Lyzenga, Gregory A.; Lyons, James R.; Manshadi, Farzin; Patterson, Jean E.

1988-01-01

A major objective of the Hypercube Matrix Computation effort at the Jet Propulsion Laboratory (JPL) is to investigate the applicability of a parallel computing architecture to the solution of large-scale electromagnetic scattering problems. Three scattering analysis codes are being implemented and assessed on a JPL/California Institute of Technology (Caltech) Mark 3 Hypercube. The codes, which utilize different underlying algorithms, give a means of evaluating the general applicability of this parallel architecture. The three analysis codes being implemented are a frequency domain method of moments code, a time domain finite difference code, and a frequency domain finite elements code. These analysis capabilities are being integrated into an electromagnetics interactive analysis workstation which can serve as a design tool for the construction of antennas and other radiating or scattering structures. The first two years of work on the Hypercube Matrix Computation effort is summarized. It includes both new developments and results as well as work previously reported in the Hypercube Matrix Computation Task: Final Report for 1986 to 1987 (JPL Publication 87-18).

Maintenance of neural progenitor cell stemness in 3D hydrogels requires matrix remodelling

NASA Astrophysics Data System (ADS)

Madl, Christopher M.; Lesavage, Bauer L.; Dewi, Ruby E.; Dinh, Cong B.; Stowers, Ryan S.; Khariton, Margarita; Lampe, Kyle J.; Nguyen, Duong; Chaudhuri, Ovijit; Enejder, Annika; Heilshorn, Sarah C.

2017-12-01

Neural progenitor cell (NPC) culture within three-dimensional (3D) hydrogels is an attractive strategy for expanding a therapeutically relevant number of stem cells. However, relatively little is known about how 3D material properties such as stiffness and degradability affect the maintenance of NPC stemness in the absence of differentiation factors. Over a physiologically relevant range of stiffness from ~0.5 to 50 kPa, stemness maintenance did not correlate with initial hydrogel stiffness. In contrast, hydrogel degradation was both correlated with, and necessary for, maintenance of NPC stemness. This requirement for degradation was independent of cytoskeletal tension generation and presentation of engineered adhesive ligands, instead relying on matrix remodelling to facilitate cadherin-mediated cell-cell contact and promote β-catenin signalling. In two additional hydrogel systems, permitting NPC-mediated matrix remodelling proved to be a generalizable strategy for stemness maintenance in 3D. Our findings have identified matrix remodelling, in the absence of cytoskeletal tension generation, as a previously unknown strategy to maintain stemness in 3D.

Modified Hartree-Fock-Bogoliubov theory at finite temperature

NASA Astrophysics Data System (ADS)

Dinh Dang, Nguyen; Arima, Akito

2003-07-01

The modified Hartree-Fock-Bogoliubov (MHFB) theory at finite temperature is derived, which conserves the unitarity relation of the particle-density matrix. This is achieved by constructing a modified-quasiparticle-density matrix, where the fluctuation of the quasiparticle number is microscopically built in. This matrix can be directly obtained from the usual quasiparticle-density matrix by applying the secondary Bogoliubov transformation, which includes the quasiparticle-occupation number. It is shown that, in the limit of constant pairing parameter, the MHFB theory yields the previously obtained modified BCS (MBCS) equations. It is also proved that the modified quasiparticle-random-phase approximation, which is based on the MBCS quasiparticle excitations, conserves the Ikeda sum rule. The numerical calculations of the pairing gap, heat capacity, level density, and level-density parameter within the MBCS theory are carried out for 120Sn. The results show that the superfluid-normal phase transition is completely washed out. The applicability of the MBCS up to a temperature as high as T˜5 MeV is analyzed in detail.

Combined effect of matrix cracking and stress-free edge on delamination

NASA Technical Reports Server (NTRS)

Salpekar, S. A.; Obrien, T. K.

1990-01-01

The effect of the stress-free edge on the growth of local delaminations initiating from a matrix crack in (0 sub 2/90 sub 4) sub s and (+ or - 45.90 sub 4) sub s glass epoxy laminates is investigated using 3-D finite element analysis. The presence of high interlaminar normal stresses at the intersection (corner) of the matrix crack with the stress-free edge, suggests that a mode I delamination may initiate at the corners. The strain energy release rates (G) were calculated by modeling a uniform through-width delamination and two inclined delaminations at 10.6 deg and 45 deg to the matrix crack. All components of G have high values near the free edges. The mode I component of G is high at small delamination length and becomes zero for a delamination length of one-ply thickness. The total G values near the free edge agreed well with previously derived closed form solution. The quasi-3D solutions agreed well with the 3-D interior solutions.

Combined effect of matrix cracking and stress-free edge on delamination

NASA Technical Reports Server (NTRS)

Salpekar, Satish A.; O'Brien, T. K.

1991-01-01

The effect of the stress-free edge on the growth of local delaminations initiating from a matrix crack in (O sub 2/90 sub 4) sub s and (+/- 45.90 sub 4) sub s glass epoxy laminates is investigated using 3D finite element analysis. The presence of high interlaminar normal stresses at the intersection (corner) of the matrix crack with the stress-free edge, suggests that a mode I delamination may initiate at the corners. The strain energy release rates (G) were calculated by modeling a uniform through-width delamination and two inclined delaminations at 10.6 deg and 45 deg to the matrix crack. All components of G have high values near the free edges. The mode I component of G is high at small delamination length and becomes zero for a delamination length of one-ply thickness. The total G values near the free edge agreed well with previously derived closed form solution. The quasi-3D solutions agreed well with the 3D interior solutions.

Maintenance of Neural Progenitor Cell Stemness in 3D Hydrogels Requires Matrix Remodeling

PubMed Central

Madl, Christopher M.; LeSavage, Bauer L.; Dewi, Ruby E.; Dinh, Cong B.; Stowers, Ryan S.; Khariton, Margarita; Lampe, Kyle J.; Nguyen, Duong; Chaudhuri, Ovijit; Enejder, Annika; Heilshorn, Sarah C.

2017-01-01

Neural progenitor cell (NPC) culture within 3D hydrogels is an attractive strategy for expanding a therapeutically-relevant number of stem cells. However, relatively little is known about how 3D material properties such as stiffness and degradability affect the maintenance of NPC stemness in the absence of differentiation factors. Over a physiologically-relevant range of stiffness from ~0.5–50 kPa, stemness maintenance did not correlate with initial hydrogel stiffness. In contrast, hydrogel degradation was both correlated with, and necessary for, maintenance of NPC stemness. This requirement for degradation was independent of cytoskeletal tension generation and presentation of engineered adhesive ligands, instead relying on matrix remodeling to facilitate cadherin-mediated cell-cell contact and promote β-catenin signaling. In two additional hydrogel systems, permitting NPC-mediated matrix remodeling proved to be a generalizable strategy for stemness maintenance in 3D. Our findings have identified matrix remodeling, in the absence of cytoskeletal tension generation, as a previously unknown strategy to maintain stemness in 3D. PMID:29115291

Shape control of structures with semi-definite stiffness matrices for adaptive wings

NASA Astrophysics Data System (ADS)

Austin, Fred; Van Nostrand, William C.; Rossi, Michael J.

1993-09-01

Maintaining an optimum-wing cross section during transonic cruise can dramatically reduce the shock-induced drag and can result in significant fuel savings and increased range. Our adaptive-wing concept employs actuators as truss elements of active ribs to reshape the wing cross section by deforming the structure. In our previous work, to derive the shape control- system gain matrix, we developed a procedure that requires the inverse of the stiffness matrix of the structure without the actuators. However, this method cannot be applied to designs where the actuators are required structural elements since the stiffness matrices are singular when the actuator are removed. Consequently, a new method was developed, where the order of the problem is reduced and only the inverse of a small nonsingular partition of the stiffness matrix is required to obtain the desired gain matrix. The procedure was experimentally validated by achieving desired shapes of a physical model of an aircraft-wing rib. The theory and test results are presented.

Matrix factorization-based data fusion for gene function prediction in baker's yeast and slime mold.

PubMed

Zitnik, Marinka; Zupan, Blaž

2014-01-01

The development of effective methods for the characterization of gene functions that are able to combine diverse data sources in a sound and easily-extendible way is an important goal in computational biology. We have previously developed a general matrix factorization-based data fusion approach for gene function prediction. In this manuscript, we show that this data fusion approach can be applied to gene function prediction and that it can fuse various heterogeneous data sources, such as gene expression profiles, known protein annotations, interaction and literature data. The fusion is achieved by simultaneous matrix tri-factorization that shares matrix factors between sources. We demonstrate the effectiveness of the approach by evaluating its performance on predicting ontological annotations in slime mold D. discoideum and on recognizing proteins of baker's yeast S. cerevisiae that participate in the ribosome or are located in the cell membrane. Our approach achieves predictive performance comparable to that of the state-of-the-art kernel-based data fusion, but requires fewer data preprocessing steps.

Matrix completion-based reconstruction for undersampled magnetic resonance fingerprinting data.

PubMed

Doneva, Mariya; Amthor, Thomas; Koken, Peter; Sommer, Karsten; Börnert, Peter

2017-09-01

An iterative reconstruction method for undersampled magnetic resonance fingerprinting data is presented. The method performs the reconstruction entirely in k-space and is related to low rank matrix completion methods. A low dimensional data subspace is estimated from a small number of k-space locations fully sampled in the temporal direction and used to reconstruct the missing k-space samples before MRF dictionary matching. Performing the iterations in k-space eliminates the need for applying a forward and an inverse Fourier transform in each iteration required in previously proposed iterative reconstruction methods for undersampled MRF data. A projection onto the low dimensional data subspace is performed as a matrix multiplication instead of a singular value thresholding typically used in low rank matrix completion, further reducing the computational complexity of the reconstruction. The method is theoretically described and validated in phantom and in-vivo experiments. The quality of the parameter maps can be significantly improved compared to direct matching on undersampled data. Copyright © 2017 Elsevier Inc. All rights reserved.

A Tensor Product Formulation of Strassen's Matrix Multiplication Algorithm with Memory Reduction

DOE PAGES

Kumar, B.; Huang, C. -H.; Sadayappan, P.; ...

1995-01-01

In this article, we present a program generation strategy of Strassen's matrix multiplication algorithm using a programming methodology based on tensor product formulas. In this methodology, block recursive programs such as the fast Fourier Transforms and Strassen's matrix multiplication algorithm are expressed as algebraic formulas involving tensor products and other matrix operations. Such formulas can be systematically translated to high-performance parallel/vector codes for various architectures. In this article, we present a nonrecursive implementation of Strassen's algorithm for shared memory vector processors such as the Cray Y-MP. A previous implementation of Strassen's algorithm synthesized from tensor product formulas required working storagemore » of size O(7 n ) for multiplying 2 n × 2 n matrices. We present a modified formulation in which the working storage requirement is reduced to O(4 n ). The modified formulation exhibits sufficient parallelism for efficient implementation on a shared memory multiprocessor. Performance results on a Cray Y-MP8/64 are presented.« less

Noise suppression for dual-energy CT via penalized weighted least-square optimization with similarity-based regularization

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

Harms, Joseph; Wang, Tonghe; Petrongolo, Michael

Purpose: Dual-energy CT (DECT) expands applications of CT imaging in its capability to decompose CT images into material images. However, decomposition via direct matrix inversion leads to large noise amplification and limits quantitative use of DECT. Their group has previously developed a noise suppression algorithm via penalized weighted least-square optimization with edge-preservation regularization (PWLS-EPR). In this paper, the authors improve method performance using the same framework of penalized weighted least-square optimization but with similarity-based regularization (PWLS-SBR), which substantially enhances the quality of decomposed images by retaining a more uniform noise power spectrum (NPS). Methods: The design of PWLS-SBR is basedmore » on the fact that averaging pixels of similar materials gives a low-noise image. For each pixel, the authors calculate the similarity to other pixels in its neighborhood by comparing CT values. Using an empirical Gaussian model, the authors assign high/low similarity value to one neighboring pixel if its CT value is close/far to the CT value of the pixel of interest. These similarity values are organized in matrix form, such that multiplication of the similarity matrix to the image vector reduces image noise. The similarity matrices are calculated on both high- and low-energy CT images and averaged. In PWLS-SBR, the authors include a regularization term to minimize the L-2 norm of the difference between the images without and with noise suppression via similarity matrix multiplication. By using all pixel information of the initial CT images rather than just those lying on or near edges, PWLS-SBR is superior to the previously developed PWLS-EPR, as supported by comparison studies on phantoms and a head-and-neck patient. Results: On the line-pair slice of the Catphan{sup ©}600 phantom, PWLS-SBR outperforms PWLS-EPR and retains spatial resolution of 8 lp/cm, comparable to the original CT images, even at 90% reduction in noise standard deviation (STD). Similar performance on spatial resolution is observed on an anthropomorphic head phantom. In addition, results of PWLS-SBR show substantially improved image quality due to preservation of image NPS. On the Catphan{sup ©}600 phantom, NPS using PWLS-SBR has a correlation of 93% with that via direct matrix inversion, while the correlation drops to −52% for PWLS-EPR. Electron density measurement studies indicate high accuracy of PWLS-SBR. On seven different materials, the measured electron densities calculated from the decomposed material images using PWLS-SBR have a root-mean-square error (RMSE) of 1.20%, while the results of PWLS-EPR have a RMSE of 2.21%. In the study on a head-and-neck patient, PWLS-SBR is shown to reduce noise STD by a factor of 3 on material images with image qualities comparable to CT images, whereas fine structures are lost in the PWLS-EPR result. Additionally, PWLS-SBR better preserves low contrast on the tissue image. Conclusions: The authors propose improvements to the regularization term of an optimization framework which performs iterative image-domain decomposition for DECT with noise suppression. The regularization term avoids calculation of image gradient and is based on pixel similarity. The proposed method not only achieves a high decomposition accuracy, but also improves over the previous algorithm on NPS as well as spatial resolution.« less

Noise suppression for dual-energy CT via penalized weighted least-square optimization with similarity-based regularization

PubMed Central

Harms, Joseph; Wang, Tonghe; Petrongolo, Michael; Niu, Tianye; Zhu, Lei

2016-01-01

Purpose: Dual-energy CT (DECT) expands applications of CT imaging in its capability to decompose CT images into material images. However, decomposition via direct matrix inversion leads to large noise amplification and limits quantitative use of DECT. Their group has previously developed a noise suppression algorithm via penalized weighted least-square optimization with edge-preservation regularization (PWLS-EPR). In this paper, the authors improve method performance using the same framework of penalized weighted least-square optimization but with similarity-based regularization (PWLS-SBR), which substantially enhances the quality of decomposed images by retaining a more uniform noise power spectrum (NPS). Methods: The design of PWLS-SBR is based on the fact that averaging pixels of similar materials gives a low-noise image. For each pixel, the authors calculate the similarity to other pixels in its neighborhood by comparing CT values. Using an empirical Gaussian model, the authors assign high/low similarity value to one neighboring pixel if its CT value is close/far to the CT value of the pixel of interest. These similarity values are organized in matrix form, such that multiplication of the similarity matrix to the image vector reduces image noise. The similarity matrices are calculated on both high- and low-energy CT images and averaged. In PWLS-SBR, the authors include a regularization term to minimize the L-2 norm of the difference between the images without and with noise suppression via similarity matrix multiplication. By using all pixel information of the initial CT images rather than just those lying on or near edges, PWLS-SBR is superior to the previously developed PWLS-EPR, as supported by comparison studies on phantoms and a head-and-neck patient. Results: On the line-pair slice of the Catphan©600 phantom, PWLS-SBR outperforms PWLS-EPR and retains spatial resolution of 8 lp/cm, comparable to the original CT images, even at 90% reduction in noise standard deviation (STD). Similar performance on spatial resolution is observed on an anthropomorphic head phantom. In addition, results of PWLS-SBR show substantially improved image quality due to preservation of image NPS. On the Catphan©600 phantom, NPS using PWLS-SBR has a correlation of 93% with that via direct matrix inversion, while the correlation drops to −52% for PWLS-EPR. Electron density measurement studies indicate high accuracy of PWLS-SBR. On seven different materials, the measured electron densities calculated from the decomposed material images using PWLS-SBR have a root-mean-square error (RMSE) of 1.20%, while the results of PWLS-EPR have a RMSE of 2.21%. In the study on a head-and-neck patient, PWLS-SBR is shown to reduce noise STD by a factor of 3 on material images with image qualities comparable to CT images, whereas fine structures are lost in the PWLS-EPR result. Additionally, PWLS-SBR better preserves low contrast on the tissue image. Conclusions: The authors propose improvements to the regularization term of an optimization framework which performs iterative image-domain decomposition for DECT with noise suppression. The regularization term avoids calculation of image gradient and is based on pixel similarity. The proposed method not only achieves a high decomposition accuracy, but also improves over the previous algorithm on NPS as well as spatial resolution. PMID:27147376

Linear constraint relations in biochemical reaction systems: I. Classification of the calculability and the balanceability of conversion rates.

PubMed

van der Heijden, R T; Heijnen, J J; Hellinga, C; Romein, B; Luyben, K C

1994-01-05

Measurements provide the basis for process monitoring and control as well as for model development and validation. Systematic approaches to increase the accuracy and credibility of the empirical data set are therefore of great value. In (bio)chemical conversions, linear conservation relations such as the balance equations for charge, enthalpy, and/or chemical elements, can be employed to relate conversion rates. In a pactical situation, some of these rates will be measured (in effect, be calculated directly from primary measurements of, e.g., concentrations and flow rates), as others can or cannot be calculated from the measured ones. When certain measured rates can also be calculated from other measured rates, the set of equations, the accuracy and credibility of the measured rates can indeed be improved by, respectively, balancing and gross error diagnosis. The balanced conversion rates are more accurate, and form a consistent set of data, which is more suitable for further application (e.g., to calculate nonmeasured rates) than the raw measurements. Such an approach has drawn attention in previous studies. The current study deals mainly with the problem of mathematically classifying the conversion rates into balanceable and calculable rates, given the subset of measured rates. The significance of this problem is illustrated with some examples. It is shown that a simple matrix equation can be derived that contains the vector of measured conversion rates and the redundancy matrix R. Matrix R plays a predominant role in the classification problem. In supplementary articles, significance of the redundancy matrix R for an improved gross error diagnosis approach will be shown. In addition, efficient equations have been derived to calculate the balanceable and/or calculable rates. The method is completely based on matrix algebra (principally different from the graph-theoretical approach), and it is easily implemented into a computer program. (c) 1994 John Wiley & Sons, Inc.

Controlled Neutralization of Anions in Cryogenic Matrices by Near-Threshold Photodetachment

NASA Astrophysics Data System (ADS)

Ludwig, Ryan M.; Moore, David T.

2014-06-01

Using matrix isolation FTIR, we have observed the formation of anionic copper carbonyl complexes [Cu(CO)n]- (n=1-3) following co-deposition of Cu- and counter-cations (Ar+ or Kr+) into argon matrices doped with CO. The infrared bands have been previously assigned in argon matrix studies employing laser ablation, however they were quite weak compared to the bands for the corresponding neutral species. In the current study, when the deposition is carried out in fully darkened conditions at 10 K with high CO concentrations (1-2%), only the bands for the anionic complexes are observed initially via FTIR. However, upon mild irradiation with broadband visible light, the anionic bands are rapidly depleted, with concomitant appearance of bands corresponding to neutral copper carbonyl complexes. This photo-triggered neutralization is attributed to photodetachment of electrons from the anions, which then "flow" through the solid argon matrix to recombine in the matrix with non-adjacent trapping sites. This mechanism is supported by the appearance of a new band near 1515 wn, assigned to the (CO)2- species in argon. The wavelength dependence of the photodetachment will be discussed in detail, although preliminary indications are that the thresholds for the copper carbonyls, which are normally in the infrared, are shifted into the visible region of the spectrum in argon matrices. This likely occurs because the conduction band of solid argon is known to lie about 1 eV above the vacuum level, and thus the electron must have at least this much energy in order to escape into the matrix and find a trapping site. Funding support from NSF CAREER Award CHE-0955637 is gratefully acknowledged Ryan M. Ludwig and David T. Moore, J. Chem. Phys. 139, 244202 (2013) Zhou, M.; Andrews, L., J. Chem. Phys. 111, 4548 (1999). Thompson, W.E.; Jacox, M.E.; J. Chem. Phys. 91, 735 (1991). Stanzel, J. et al.; Collect. Czech. Chem. Comm. 72, 1 (2007). Harbich, W. et al.; Phys. Rev. B. 76, 104306 (2007).

Matrix Metalloproteinase 9 in Epilepsy: The Role of Neuroinflammation in Seizure Development

PubMed Central

2016-01-01

Matrix metalloproteinase 9 is a proteolytic enzyme which is recently one of the more often studied biomarkers. Its possible use as a biomarker of neuronal damage in stroke, heart diseases, tumors, multiple sclerosis, and epilepsy is being widely indicated. In epilepsy, MMP-9 is suggested to play a role in epileptic focus formation and in the stimulation of seizures. The increase of MMP-9 activity in the epileptic focus was observed both in animal models and in clinical studies. MMP-9 contributes to formation of epileptic focus, for example, by remodeling of synapses. Its proteolytic action on the elements of blood-brain barrier and activation of chemotactic processes facilitates accumulation of inflammatory cells and induces seizures. Also modification of glutamatergic transmission by MMP-9 is associated with seizures. In this review we will try to recapitulate the results of previous studies about MMP-9 in terms of its association with epilepsy. We will discuss the mechanisms of its actions and present the results revealed in animal models and clinical studies. We will also provide a comparison of the results of various studies on MMP-9 levels in the context of its possible use as a biomarker of the activity of epilepsy. PMID:28104930

Dimerization of Matrix Metalloproteinase-2 (MMP-2)

PubMed Central

Koo, Bon-Hun; Kim, Yeon Hyang; Han, Jung Ho; Kim, Doo-Sik

2012-01-01

Matrix metalloproteinase-2 (MMP-2) functions in diverse biological processes through the degradation of extracellular and non-extracellular matrix molecules. Because of its potential for tissue damage, there are several ways to regulate MMP-2 activity, including gene expression, compartmentalization, zymogen activation, and enzyme inactivation by extracellular inhibitors. Enzyme regulation through zymogen activation is important for the regulation of MMP-2 activity. In our previous studies, we showed that thrombin directly cleaved the propeptide of MMP-2 at specific sites for enzyme activation. We also demonstrated that heparan sulfate was required for thrombin-mediated activation of pro-MMP-2 by binding to thrombin, presumably through conformational changes at the active site of the enzyme. This suggests a regulatory mechanism for thrombin-mediated activation of pro-MMP-2. In this study, we found that MMP-2 formed a reduction-sensitive homodimer in a controlled manner and that Ca2+ ion was essential for homodimerization of MMP-2. Homodimerization was not associated with protein kinase C-mediated phosphorylation of MMP-2. MMP-2 formed a homodimer through an intermolecular disulfide bond between Cys102 and the neighboring Cys102. Homodimerization of MMP-2 enhanced thrombin-mediated activation of pro-MMP-2. Moreover, the MMP-2 homodimer could cleave a small peptide substrate without removal of the propeptide. Taken together, our experimental data suggest a novel regulatory mechanism for pro-MMP-2 activation that is modulated through homodimerization of MMP-2. PMID:22577146

Quantitative estimation of the cost of parasitic castration in a Helisoma anceps population using a matrix population model.

PubMed

Negovetich, N J; Esch, G W

2008-10-01

Larval trematodes frequently castrate their snail intermediate hosts. When castrated, the snails do not contribute offspring to the population, yet they persist and compete with the uninfected individuals for the available food resources. Parasitic castration should reduce the population growth rate lambda, but the magnitude of this decrease is unknown. The present study attempted to quantify the cost of parasitic castration at the level of the population by mathematically modeling the population of the planorbid snail Helisoma anceps in Charlie's Pond, North Carolina. Analysis of the model identified the life-history trait that most affects lambda, and the degree to which parasitic castration can lower lambda. A period matrix product model was constructed with estimates of fecundity, survival, growth rates, and infection probabilities calculated in a previous study. Elasticity analysis was performed by increasing the values of the life-history traits by 10% and recording the percentage change in lambda. Parasitic castration resulted in a 40% decrease in lambda of H. anceps. Analysis of the model suggests that decreasing the size at maturity was more effective at reducing the cost of castration than increasing survival or growth rates of the snails. The current matrix model was the first to mathematically describe a snail population, and the predictions of the model are in agreement with published research.

Carbon concentration measurements by atom probe tomography in the ferritic phase of high-silicon steels

DOE PAGES

Rementeria, Rosalia; Poplawsky, Jonathan D.; Aranda, Maria M.; ...

2016-12-19

Current studies using atom probe tomography (APT) show that bainitic ferrite formed at low temperature contains more carbon than what is consistent with the paraequilibrium phase diagram. However, nanocrystalline bainitic ferrite exhibits a non-homogeneous distribution of carbon atoms in arrangements with specific compositions, i.e. Cottrell atmospheres, carbon clusters, and carbides, in most cases with a size of a few nanometers. The ferrite volume within a single platelet that is free of these carbon-enriched regions is extremely small. Proximity histograms can be compromised on the ferrite side, and a great deal of care should be taken to estimate the carbon contentmore » in regions of bainitic ferrite free from carbon agglomeration. For this purpose, APT measurements were first validated for the ferritic phase in a pearlitic sample and further performed for the bainitic ferrite matrix in high-silicon steels isothermally transformed between 200 °C and 350 °C. Additionally, results were compared with the carbon concentration values derived from X-ray diffraction (XRD) analyses considering a tetragonal lattice and previous APT studies. In conclusion, the present results reveal a strong disagreement between the carbon content values in the bainitic ferrite matrix as obtained by APT and those derived from XRD measurements. Those differences have been attributed to the development of carbon-clustered regions with an increased tetragonality in a carbon-depleted matrix.« less

Extracellular Matrix Hydrogel Derived from Human Umbilical Cord as a Scaffold for Neural Tissue Repair and Its Comparison with Extracellular Matrix from Porcine Tissues.

PubMed

Kočí, Zuzana; Výborný, Karel; Dubišová, Jana; Vacková, Irena; Jäger, Aleš; Lunov, Oleg; Jiráková, Klára; Kubinová, Šárka

2017-06-01

Extracellular matrix (ECM) hydrogels prepared by tissue decellularization have been reported as natural injectable materials suitable for neural tissue repair. In this study, we prepared ECM hydrogel derived from human umbilical cord (UC) and evaluated its composition and mechanical and biological properties in comparison with the previously described ECM hydrogels derived from porcine urinary bladder (UB), brain, and spinal cord. The ECM hydrogels did not differ from each other in the concentration of collagen, while the highest content of glycosaminoglycans as well as the shortest gelation time was found for UC-ECM. The elastic modulus was then found to be the highest for UB-ECM. In spite of a different origin, topography, and composition, all ECM hydrogels similarly promoted the migration of human mesenchymal stem cells (MSCs) and differentiation of neural stem cells, as well as axonal outgrowth in vitro. However, only UC-ECM significantly improved proliferation of tissue-specific UC-derived MSCs when compared with the other ECMs. Injection of UC-ECM hydrogels into a photothrombotic cortical ischemic lesion in rats proved its in vivo gelation and infiltration with host macrophages. In summary, this study proposes UC-ECM hydrogel as an easily accessible biomaterial of human origin, which has the potential for neural as well as other soft tissue reconstruction.

Sparse representation of whole-brain fMRI signals for identification of functional networks.

PubMed

Lv, Jinglei; Jiang, Xi; Li, Xiang; Zhu, Dajiang; Chen, Hanbo; Zhang, Tuo; Zhang, Shu; Hu, Xintao; Han, Junwei; Huang, Heng; Zhang, Jing; Guo, Lei; Liu, Tianming

2015-02-01

There have been several recent studies that used sparse representation for fMRI signal analysis and activation detection based on the assumption that each voxel's fMRI signal is linearly composed of sparse components. Previous studies have employed sparse coding to model functional networks in various modalities and scales. These prior contributions inspired the exploration of whether/how sparse representation can be used to identify functional networks in a voxel-wise way and on the whole brain scale. This paper presents a novel, alternative methodology of identifying multiple functional networks via sparse representation of whole-brain task-based fMRI signals. Our basic idea is that all fMRI signals within the whole brain of one subject are aggregated into a big data matrix, which is then factorized into an over-complete dictionary basis matrix and a reference weight matrix via an effective online dictionary learning algorithm. Our extensive experimental results have shown that this novel methodology can uncover multiple functional networks that can be well characterized and interpreted in spatial, temporal and frequency domains based on current brain science knowledge. Importantly, these well-characterized functional network components are quite reproducible in different brains. In general, our methods offer a novel, effective and unified solution to multiple fMRI data analysis tasks including activation detection, de-activation detection, and functional network identification. Copyright © 2014 Elsevier B.V. All rights reserved.

Investigation and modeling of the elastic-plastic fracture behavior of continuous woven fabric-reinforced ceramic composites

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

Kahl, W.K.

1997-03-01

The paper describes a study which attempted to extrapolate meaningful elastic-plastic fracture toughness data from flexure tests of a chemical vapor-infiltrated SiC/Nicalon fiber-reinforced ceramic matrix composite. Fibers in the fabricated composites were pre-coated with pyrolytic carbon to varying thicknesses. In the tests, crack length was not measured and the study employed an estimate procedure, previously used successfully for ductile metals, to derive J-R curve information. Results are presented in normalized load vs. normalized displacements and comparative J{sub Ic} behavior as a function of fiber precoating thickness.

Detection of HOCl-mediated protein oxidation products in the extracellular matrix of human atherosclerotic plaques.

PubMed Central

Woods, Alan A; Linton, Stuart M; Davies, Michael J

2003-01-01

Oxidation is believed to play a role in atherosclerosis. Oxidized lipids, sterols and proteins have been detected in early, intermediate and advanced human lesions at elevated levels. The spectrum of oxidized side-chain products detected on proteins from homogenates of advanced human lesions has been interpreted in terms of the occurrence of two oxidative mechanisms, one involving oxygen-derived radicals catalysed by trace transition metal ions, and a second involving chlorinating species (HOCl or Cl2), generated by the haem enzyme myeloperoxidase (MPO). As MPO is released extracellularly by activated monocytes (and possibly macrophages) and is a highly basic protein, it would be expected to associate with polyanions such as the glycosaminoglycans of the extracellular matrix, and might result in damage being localized at such sites. In this study proteins extracted from extracellular matrix material obtained from advanced human atherosclerotic lesions are shown to contain elevated levels of oxidized amino acids [3,4-dihydroxyphenylalanine (DOPA), di-tyrosine, 2-hydroxyphenylalanine ( o-Tyr)] when compared with healthy (human and pig) arterial tissue. These matrix-derived materials account for 83-96% of the total oxidized protein side-chain products detected in these plaques. Oxidation of matrix components extracted from healthy artery tissue, and model proteins, with reagent HOCl is shown to give rise to a similar pattern of products to those detected in advanced human lesions. The detection of elevated levels of DOPA and o-Tyr, which have been previously attributed to the occurrence of oxygen-radical-mediated reactions, by HOCl treatment, suggests an alternative route to the formation of these materials in plaques. This is believed to involve the formation and subsequent decomposition of protein chloramines. PMID:12456264

A study of the native cell wall structures of the marine alga Ventricaria ventricosa (Siphonocladales, Chlorophyceae) using atomic force microscopy.

PubMed

Eslick, Enid M; Beilby, Mary J; Moon, Anthony R

2014-04-01

A substantial proportion of the architecture of the plant cell wall remains unknown with a few cell wall models being proposed. Moreover, even less is known about the green algal cell wall. Techniques that allow direct visualization of the cell wall in as near to its native state are of importance in unravelling the spatial arrangement of cell wall structures and hence in the development of cell wall models. Atomic force microscopy (AFM) was used to image the native cell wall of living cells of Ventricaria ventricosa (V. ventricosa) at high resolution under physiological conditions. The cell wall polymers were identified mainly qualitatively via their structural appearance. The cellulose microfibrils (CMFs) were easily recognizable and the imaging results indicate that the V. ventricosa cell wall has a cross-fibrillar structure throughout. We found the native wall to be abundant in matrix polysaccharides existing in different curing states. The soft phase matrix polysaccharides susceptible by the AFM scanning tip existed as a glutinous fibrillar meshwork, possibly incorporating both the pectic- and hemicellulosic-type substances. The hard phase matrix producing clearer images, revealed coiled fibrillar structures associated with CMFs, sometimes being resolved as globular structures by the AFM tip. The coiling fibrillar structures were also seen in the images of isolated cell wall fragments. The mucilaginous component of the wall was discernible from the gelatinous cell wall matrix as it formed microstructural domains over the surface. AFM has been successful in imaging the native cell wall and revealing novel findings such as the 'coiling fibrillar structures' and cell wall components which have previously not been seen, that is, the gelatinous matrix phase.

Dynamics of water in strawberry and red onion as studied by dielectric spectroscopy

NASA Astrophysics Data System (ADS)

Jansson, H.; Huldt, C.; Bergman, R.; Swenson, J.

2005-01-01

We have investigated the microscopic dynamics of strawberry and red onion by means of broadband dielectric spectroscopy. In contrast to most of the previous experiments on carbohydrate-rich biological materials, which have mainly considered the more global dynamics of the “biological matrix,” we are here focusing on the microscopic dynamics of mainly the associated water. The results for both strawberry and red onion show that the imaginary part of the permittivity contains one conductivity term and a clear dielectric loss peak, which was found to be similar to the strongest relaxation process of water in carbohydrate solutions. The temperature dependence of the relaxation process was analyzed for different water content. The relaxation process slows down, and its temperature dependence becomes more non-Arrhenius, with decreasing water content. The reason for this is most likely that, on average, the water molecules interact more strongly with carbohydrates and other biological materials at low water content, and the dynamical properties of this biological matrix changes substantially with increasing temperature (from an almost rigid matrix where the water is basically unable to perform long-range diffusion due to confinement effects, to a dynamic matrix with no static confinement effects), which also changes (i.e., reduces) the activation energy of the relaxation process with increasing temperature (i.e., causes a non-Arrhenius temperature dependence). This further changes the conductivity from mainly polarization effects at low temperatures, due to hindered ionic motions, to long-range diffusivity at T>250K . Thus, around this temperature ions in the carbohydrate solution no longer get stuck in confined cavities, since the motion of the biological matrix “opens up” the cavities and the ions are then able to perform long-range migration.

Formation of Hydrogen Sulfide in Wine: Interactions between Copper and Sulfur Dioxide.

PubMed

Bekker, Marlize Z; Smith, Mark E; Smith, Paul A; Wilkes, Eric N

2016-09-10

The combined synergistic effects of copper (Cu(2+)) and sulfur dioxide (SO₂) on the formation of hydrogen sulfide (H₂S) in Verdelho and Shiraz wine samples post-bottling was studied over a 12-month period. The combined treatment of Cu(2+) and SO₂ significantly increased H₂S formation in Verdelho wines samples that were not previously treated with either Cu(2+) or SO₂. The formation of H₂S produced through Cu(2+) mediated reactions was likely either: (a) directly through the interaction of SO₂ with either Cu(2+) or H₂S; or (b) indirectly through the interaction of SO₂ with other wine matrix compounds. To gain better understanding of the mechanisms responsible for the significant increases in H₂S concentration in the Verdelho samples, the interaction between Cu(2+) and SO₂ was studied in a model wine matrix with and without the presence of a representative thiol quenching compound (4-methylbenzoquinone, 4MBQ). In these model studies, the importance of naturally occurring wine compounds and wine additives, such as quinones, SO₂, and metal ions, in modulating the formation of H₂S post-bottling was demonstrated. When present in equimolar concentrations a 1:1 ratio of H₂S- and SO₂-catechol adducts were produced. At wine relevant concentrations, however, only SO₂-adducts were produced, reinforcing that the competition reactions of sulfur nucleophiles, such as H₂S and SO₂, with wine matrix compounds play a critical role in modulating final H₂S concentrations in wines.

Fatigue behavior of a cross-ply metal matrix composite at elevated temperature under the strain controlled mode

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

Sanders, B.P.; Mall, S.; Dennis, L.B.

1997-10-01

A study was conducted to investigate the fatigue behavior of a cross-ply metal matrix composite subjected to fully-reversed, strain-controlled fatigue cycling at elevated temperature. The stress-strain response, maximum and minimum stresses, and modulus during cycling were analyzed to characterize the macro-mechanical behavior. Additionally, microscopy and fractography were conducted to identify damage mechanisms. Damage always initiated in the 90 deg plies, but the governing factor in the fatigue life was damage in the 0 deg plies. The dominant failure mode was fracturing of fibers in the 0 deg plies when the maximum strain was greater than 0.55%, but the dominant failuremore » mode was matrix cracking when the maximum strain was less than 0.55%. Combining the fatigue life data with the macro-mechanical and microscopic observations, a fatigue life diagram was developed and partitioned into three regions. These regions showed relationships between the maximum applied strain and the dominant damage mechanisms. Also, on a strain range basis, the fatigue lives of the specimens tested under the strain-controlled mode in this study were compared with its counterpart under the load-controlled mode of the previous study. It was found that the fatigue lives for these two conditions were the same within the experimental scatter. The MMC tested in this investigation was the Ti-15V-3Cr-3Al-3Sn titanium alloy reinforced with 36 volume percent of silicon carbide fibers (SCS-6).« less

Random matrix theory analysis of cross-correlations in the US stock market: Evidence from Pearson’s correlation coefficient and detrended cross-correlation coefficient

NASA Astrophysics Data System (ADS)

Wang, Gang-Jin; Xie, Chi; Chen, Shou; Yang, Jiao-Jiao; Yang, Ming-Yan

2013-09-01

In this study, we first build two empirical cross-correlation matrices in the US stock market by two different methods, namely the Pearson’s correlation coefficient and the detrended cross-correlation coefficient (DCCA coefficient). Then, combining the two matrices with the method of random matrix theory (RMT), we mainly investigate the statistical properties of cross-correlations in the US stock market. We choose the daily closing prices of 462 constituent stocks of S&P 500 index as the research objects and select the sample data from January 3, 2005 to August 31, 2012. In the empirical analysis, we examine the statistical properties of cross-correlation coefficients, the distribution of eigenvalues, the distribution of eigenvector components, and the inverse participation ratio. From the two methods, we find some new results of the cross-correlations in the US stock market in our study, which are different from the conclusions reached by previous studies. The empirical cross-correlation matrices constructed by the DCCA coefficient show several interesting properties at different time scales in the US stock market, which are useful to the risk management and optimal portfolio selection, especially to the diversity of the asset portfolio. It will be an interesting and meaningful work to find the theoretical eigenvalue distribution of a completely random matrix R for the DCCA coefficient because it does not obey the Marčenko-Pastur distribution.

An Alternative Theory of the Universe Based Upon a Balanced Particulate-Ethereal, Tri-Based, Ten-Dimensional, Self-Propagating Matrix

NASA Astrophysics Data System (ADS)

Cogley, Thomas

2010-02-01

A model of the Universe of man designated ``MU'' is proposed. Based upon 10 working and 1 generating dimension or firmament the makeup of MU will be described. The balance of the Universe and the position form of time space and gravity will be described. The particulate physical and ethereal nature is one that departs from previous theories but is of the utmost importance in balancing the Universe and accounting for the shortfalls of the proposed theories of the day. The ten-dimensional +1 matrix will be described along with its sub-parts each distinct and closely bound to a separate dimensional level. The connections or doors between the firmaments and the methods by which they stay open close and remain separated from each other is described. Of great importance is the propagation of a firmament within the Matrix. Each firmament is itself independent and distinctly wrapped by a unique layer of the matrix. Yet each firmament is itself a separate image or part of the next larger firmament as can be thought of a subunit of that firmament. Thus each is separate yet still a part of the greater sized firmament that follows. The sizes of the dimensions are in a repeatable and constant multiple of the previous dimension. Sizes of the dimensions will be discussed. The function, form, and structural layout of the universe will be shown to have a fractal relationship to natural systems on earth and even to the image of man. )

The multifacet graphically contracted function method. I. Formulation and implementation

NASA Astrophysics Data System (ADS)

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

2014-08-01

The basic formulation for the multifacet generalization of the graphically contracted function (MFGCF) electronic structure method is presented. The analysis includes the discussion of linear dependency and redundancy of the arc factor parameters, the computation of reduced density matrices, Hamiltonian matrix construction, spin-density matrix construction, the computation of optimization gradients for single-state and state-averaged calculations, graphical wave function analysis, and the efficient computation of configuration state function and Slater determinant expansion coefficients. Timings are given for Hamiltonian matrix element and analytic optimization gradient computations for a range of model problems for full-CI Shavitt graphs, and it is observed that both the energy and the gradient computation scale as O(N2n4) for N electrons and n orbitals. The important arithmetic operations are within dense matrix-matrix product computational kernels, resulting in a computationally efficient procedure. An initial implementation of the method is used to present applications to several challenging chemical systems, including N2 dissociation, cubic H8 dissociation, the symmetric dissociation of H2O, and the insertion of Be into H2. The results are compared to the exact full-CI values and also to those of the previous single-facet GCF expansion form.

The multifacet graphically contracted function method. I. Formulation and implementation.

PubMed

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

2014-08-14

The basic formulation for the multifacet generalization of the graphically contracted function (MFGCF) electronic structure method is presented. The analysis includes the discussion of linear dependency and redundancy of the arc factor parameters, the computation of reduced density matrices, Hamiltonian matrix construction, spin-density matrix construction, the computation of optimization gradients for single-state and state-averaged calculations, graphical wave function analysis, and the efficient computation of configuration state function and Slater determinant expansion coefficients. Timings are given for Hamiltonian matrix element and analytic optimization gradient computations for a range of model problems for full-CI Shavitt graphs, and it is observed that both the energy and the gradient computation scale as O(N(2)n(4)) for N electrons and n orbitals. The important arithmetic operations are within dense matrix-matrix product computational kernels, resulting in a computationally efficient procedure. An initial implementation of the method is used to present applications to several challenging chemical systems, including N2 dissociation, cubic H8 dissociation, the symmetric dissociation of H2O, and the insertion of Be into H2. The results are compared to the exact full-CI values and also to those of the previous single-facet GCF expansion form.

HPLC-MS/MS method optimisation for matrix metalloproteinase 3 and matrix metalloproteinase 9 determination in human blood serum using target analysis.

PubMed

Kotnik, Petra; Krajnc, Metka Koren; Pahor, Artur; Finšgar, Matjaž; Knez, Željko

2018-02-20

A quantitative analysis of zinc endopeptidases matrix metalloproteinase 9 (MMP9) and matrix metalloproteinase 3 (MMP3) from human blood serum are presented. Both matrix metalloproteinases (MMP) are present in human blood serum and can be used as biomarkers for different diseases. The analysis was performed using LC-MS/MS with a triple quadrupole mass spectrometer, based on two specific peptides of each MMP in comparison with an enzyme-linked immunosorbent assay (ELISA). While the conditions for the LC-MS/MS analysis of MMP9 peptides were previously reported for bronchoalveolar lavage fluid, the analysis of MMP3 peptides was newly quantified for human blood serum herein for the first time. For MMP3, the linear behaviour was determined in the concentration range from 1.0-200.0ng/mL (R 2 =0.997) with an LLOD of 0.5ng/mL. For MMP9, linearity was determined in the concentration range from 6.5-65.0ng/mL (R 2 =0.995) with an LLOD of 2.0ng/mL. Copyright © 2017 Elsevier B.V. All rights reserved.

Diesel Exhaust Exposure and the Risk of Lung Cancer—A Review of the Epidemiological Evidence

PubMed Central

Sun, Yi; Bochmann, Frank; Nold, Annette; Mattenklott, Markus

2014-01-01

To critically evaluate the association between diesel exhaust (DE) exposure and the risk of lung cancer, we conducted a systematic review of published epidemiological evidences. To comprehensively identify original studies on the association between DE exposure and the risk of lung cancer, literature searches were performed in literature databases for the period between 1970 and 2013, including bibliographies and cross-referencing. In total, 42 cohort studies and 32 case-control studies were identified in which the association between DE exposures and lung cancer was examined. In general, previous studies suffer from a series of methodological limitations, including design, exposure assessment methods and statistical analysis used. A lack of objective exposure information appears to be the main problem in interpreting epidemiological evidence. To facilitate the interpretation and comparison of previous studies, a job-exposure matrix (JEM) of DE exposures was created based on around 4,000 historical industrial measurements. The values from the JEM were considered during interpretation and comparison of previous studies. Overall, neither cohort nor case-control studies indicate a clear exposure-response relationship between DE exposure and lung cancer. Epidemiological studies published to date do not allow a valid quantification of the association between DE and lung cancer. PMID:24473109

An Algebraic Construction of Duality Functions for the Stochastic {U_q( A_n^{(1)})} Vertex Model and Its Degenerations

NASA Astrophysics Data System (ADS)

Kuan, Jeffrey

2018-03-01

A recent paper (Kuniba in Nucl Phys B 913:248-277, 2016) introduced the stochastic U}_q(A_n^{(1)})} vertex model. The stochastic S-matrix is related to the R-matrix of the quantum group {U_q(A_n^{(1)})} by a gauge transformation. We will show that a certain function {D^+_{m intertwines with the transfer matrix and its space reversal. When interpreting the transfer matrix as the transition matrix of a discrete-time totally asymmetric particle system on the one-dimensional lattice Z , the function {D^+m} becomes a Markov duality function {Dm} which only depends on q and the vertical spin parameters μ_x. By considering degenerations in the spectral parameter, the duality results also hold on a finite lattice with closed boundary conditions, and for a continuous-time degeneration. This duality function had previously appeared in a multi-species ASEP(q, j) process (Kuan in A multi-species ASEP(q, j) and q-TAZRP with stochastic duality, 2017). The proof here uses that the R-matrix intertwines with the co-product, but does not explicitly use the Yang-Baxter equation. It will also be shown that the stochastic U}_q(A_n^{(1)})} is a multi-species version of a stochastic vertex model studied in Borodin and Petrov (Higher spin six vertex model and symmetric rational functions, 2016) and Corwin and Petrov (Commun Math Phys 343:651-700, 2016). This will be done by generalizing the fusion process of Corwin and Petrov (2016) and showing that it matches the fusion of Kulish and yu (Lett Math Phys 5:393-403, 1981) up to the gauge transformation. We also show, by direct computation, that the multi-species q-Hahn Boson process (which arises at a special value of the spectral parameter) also satisfies duality with respect to D_∞, generalizing the single-species result of Corwin (Int Math Res Not 2015:5577-5603, 2015).

Internal energy deposition with silicon nanoparticle-assisted laser desorption/ionization (SPALDI) mass spectrometry

NASA Astrophysics Data System (ADS)

Dagan, Shai; Hua, Yimin; Boday, Dylan J.; Somogyi, Arpad; Wysocki, Ronald J.; Wysocki, Vicki H.

2009-06-01

The use of silicon nanoparticles for laser desorption/ionization (LDI) is a new appealing matrix-less approach for the selective and sensitive mass spectrometry of small molecules in MALDI instruments. Chemically modified silicon nanoparticles (30 nm) were previously found to require very low laser fluence in order to induce efficient LDI, which raised the question of internal energy deposition processes in that system. Here we report a comparative study of internal energy deposition from silicon nanoparticles to previously explored benzylpyridinium (BP) model compounds during LDI experiments. The internal energy deposition in silicon nanoparticle-assisted laser desorption/ionization (SPALDI) with different fluorinated linear chain modifiers (decyl, hexyl and propyl) was compared to LDI from untreated silicon nanoparticles and from the organic matrix, [alpha]-cyano-4-hydroxycinnamic acid (CHCA). The energy deposition to internal vibrational modes was evaluated by molecular ion survival curves and indicated that the ions produced by SPALDI have an internal energy threshold of 2.8-3.7 eV. This is slightly lower than the internal energy induced using the organic CHCA matrix, with similar molecular survival curves as previously reported for LDI off silicon nanowires. However, the internal energy associated with desorption/ionization from the silicon nanoparticles is significantly lower than that reported for desorption/ionization on silicon (DIOS). The measured survival yields in SPALDI gradually decrease with increasing laser fluence, contrary to reported results for silicon nanowires. The effect of modification of the silicon particle surface with semifluorinated linear chain silanes, including fluorinated decyl (C10), fluorinated hexyl (C6) and fluorinated propyl (C3) was explored too. The internal energy deposited increased with a decrease in the length of the modifier alkyl chain. Unmodified silicon particles exhibited the highest analyte internal energy deposition. These findings may suggest a role of the modifier as a moderator in the energy dissipation and relaxation process. The relatively low internal energy content of SPALDI-produced ions indicates that this is a "soft" desorption technique, with potential advantages in the analysis of labile compounds.

Chinchilla middle ear transmission matrix model and middle-ear flexibilitya)

PubMed Central

Ravicz, Michael E.; Rosowski, John J.

2017-01-01

The function of the middle ear (ME) in transforming ME acoustic inputs and outputs (sound pressures and volume velocities) can be described with an acoustic two-port transmission matrix. This description is independent of the load on the ME (cochlea or ear canal) and holds in either direction: forward (from ear canal to cochlea) or reverse (from cochlea to ear canal). A transmission matrix describing ME function in chinchilla, an animal commonly used in auditory research, is presented, computed from measurements of forward ME function: input admittance YTM, ME pressure gain GMEP, ME velocity transfer function HV, and cochlear input admittance YC, in the same set of ears [Ravicz and Rosowski (2012b). J. Acoust. Soc. Am. 132, 2437–2454; (2013a). J. Acoust. Soc. Am. 133, 2208–2223; (2013b). J. Acoust. Soc. Am. 134, 2852–2865]. Unlike previous estimates, these computations require no assumptions about the state of the inner ear, effectiveness of ME manipulations, or measurements of sound transmission in the reverse direction. These element values are generally consistent with physical constraints and the anatomical ME “transformer ratio.” Differences from a previous estimate in chinchilla [Songer and Rosowski (2007). J. Acoust. Soc. Am. 122, 932–942] may be due to a difference in ME flexibility between the two subject groups. PMID:28599566

Chinchilla middle ear transmission matrix model and middle-ear flexibility.

PubMed

Ravicz, Michael E; Rosowski, John J

2017-05-01

The function of the middle ear (ME) in transforming ME acoustic inputs and outputs (sound pressures and volume velocities) can be described with an acoustic two-port transmission matrix. This description is independent of the load on the ME (cochlea or ear canal) and holds in either direction: forward (from ear canal to cochlea) or reverse (from cochlea to ear canal). A transmission matrix describing ME function in chinchilla, an animal commonly used in auditory research, is presented, computed from measurements of forward ME function: input admittance Y TM , ME pressure gain G MEP , ME velocity transfer function H V , and cochlear input admittance Y C , in the same set of ears [Ravicz and Rosowski (2012b). J. Acoust. Soc. Am. 132, 2437-2454; (2013a). J. Acoust. Soc. Am. 133, 2208-2223; (2013b). J. Acoust. Soc. Am. 134, 2852-2865]. Unlike previous estimates, these computations require no assumptions about the state of the inner ear, effectiveness of ME manipulations, or measurements of sound transmission in the reverse direction. These element values are generally consistent with physical constraints and the anatomical ME "transformer ratio." Differences from a previous estimate in chinchilla [Songer and Rosowski (2007). J. Acoust. Soc. Am. 122, 932-942] may be due to a difference in ME flexibility between the two subject groups.

The essential role of inorganic substrate in the migration and osteoblastic differentiation of mesenchymal stem cells.

PubMed

He, Jing; Meng, Guolong; Yao, Ruijuan; Jiang, Bo; Wu, Yao; Wu, Fang

2016-06-01

The physical environment, which is an integral part of the stem cell niche, is critical in regulating stem cell functions and differentiation into specific lineages. Previous studies have primarily focused on modulating the polymeric matrixes, including the extracellular matrix. Here, we report that the presence of the inorganic substrate (Ti and hydroxyapatite (HA)) in addition to the collagen overlayer plays an essential role in cytoskeletal organization, migration and differentiation of mesenchymal stem cells (MSCs). The osteogenic differentiation of MSCs was suppressed on pure collagen substrate alone, despite collagen greatly enhancing the MSC adhesion and proliferation. The results indicated a strong correlation between MSC motility and osteoblastic differentiation. In particular, the presence of the inorganic matrix promoted the activation of the canonical WNT-β-Catenin pathway and stimulated transcription, leading to osteoblastic differentiation, which was likely due to the internal forces generated "dynamically" during cell migration. Compared to the Ti substrate, hydroxyapatite promoted the collagen self-assembly and the formation of the collagen fibrous network, which is critical for MSC motility and osteogenic differentiation. The HA-collagen matrix exhibited the most favourable stress fibre formation, the longest migration distance (2.8-fold higher than that of the pure collagen sample and 1.9-fold higher than that of Ti-collagen), and the best osteogenic differentiation activities. These findings might have important implications for our understanding of the fundamental MSC functions and the optimal design of bone regeneration materials. Copyright © 2016 Elsevier Ltd. All rights reserved.

A Framework for Integrated Component and System Analyses of Instabilities

NASA Technical Reports Server (NTRS)

Ahuja, Vineet; Erwin, James; Arunajatesan, Srinivasan; Cattafesta, Lou; Liu, Fei

2010-01-01

Instabilities associated with fluid handling and operation in liquid rocket propulsion systems and test facilities usually manifest themselves as structural vibrations or some form of structural damage. While the source of the instability is directly related to the performance of a component such as a turbopump, valve or a flow control element, the associated pressure fluctuations as they propagate through the system have the potential to amplify and resonate with natural modes of the structural elements and components of the system. In this paper, the authors have developed an innovative multi-level approach that involves analysis at the component and systems level. The primary source of the unsteadiness is modeled with a high-fidelity hybrid RANS/LES based CFD methodology that has been previously used to study instabilities in feed systems. This high fidelity approach is used to quantify the instability and understand the physics associated with the instability. System response to the driving instability is determined through a transfer matrix approach wherein the incoming and outgoing pressure and velocity fluctuations are related through a transfer (or transmission) matrix. The coefficients of the transfer matrix for each component (i.e. valve, pipe, orifice etc.) are individually derived from the flow physics associated with the component. A demonstration case representing a test loop/test facility comprised of a network of elements is constructed with the transfer matrix approach and the amplification of modes analyzed as the instability propagates through the test loop.

Differential continuum damage mechanics models for creep and fatigue of unidirectional metal matrix composites

NASA Technical Reports Server (NTRS)

Arnold, S. M.; Kruch, S.

1991-01-01

Three multiaxial isothermal continuum damage mechanics models for creep, fatigue, and creep/fatigue interaction of a unidirectional metal matrix composite volume element are presented, only one of which will be discussed in depth. Each model is phenomenological and stress based, with varying degrees of complexity to accurately predict the initiation and propagation of intergranular and transgranular defects over a wide range of loading conditions. The development of these models is founded on the definition of an initially transversely isotropic fatigue limit surface, static fracture surface, normalized stress amplitude function and isochronous creep damage failure surface, from which both fatigue and creep damage evolutionary laws can be obtained. The anisotropy of each model is defined through physically meaningful invariants reflecting the local stress and material orientation. All three transversely isotropic models have been shown, when taken to their isotropic limit, to directly simplify to previously developed and validated creep and fatigue continuum damage theories. Results of a nondimensional parametric study illustrate (1) the flexibility of the present formulation when attempting to characterize a large class of composite materials, and (2) its ability to predict anticipated qualitative trends in the fatigue behavior of unidirectional metal matrix composites. Additionally, the potential for the inclusion of various micromechanical effects (e.g., fiber/matrix bond strength, fiber volume fraction, etc.), into the phenomenological anisotropic parameters is noted, as well as a detailed discussion regarding the necessary exploratory and characterization experiments needed to utilize the featured damage theories.

Mitochondrial p53 mediates a transcription-independent regulation of cell respiration and interacts with the mitochondrial F₁F₀-ATP synthase

PubMed Central

Bergeaud, Marie; Mathieu, Lise; Guillaume, Arnaud; Moll, Ute M; Mignotte, Bernard; Le Floch, Nathalie; Vayssière, Jean-Luc; Rincheval, Vincent

2013-01-01

We and others previously reported that endogenous p53 can be located at mitochondria in the absence of stress, suggesting that p53 has a role in the normal physiology of this organelle. The aim of this study was to characterize in unstressed cells the intramitochondrial localization of p53 and identify new partners and functions of p53 in mitochondria. We find that the intramitochondrial pool of p53 is located in the intermembrane space and the matrix. Of note, unstressed HCT116 p53+/+ cells simultaneously show increased O₂ consumption and decreased mitochondrial superoxide production compared with their p53-null counterpart. This data was confirmed by stable H1299 cell lines expressing low levels of p53 specifically targeted to the matrix. Using immunoprecipitation and mass spectrometry, we identified the oligomycin sensitivity-conferring protein (OSCP), a subunit of the F₁F₀-ATP synthase complex, as a new partner of endogenous p53, specifically interacting with p53 localized in the matrix. Interestingly, this interaction seems implicated in mitochondrial p53 localization. Moreover, p53 localized in the matrix promotes the assembly of F₁F₀-ATP synthase. Taking into account that deregulations of mitochondrial respiration and reactive oxygen species production are tightly linked to cancer development, we suggest that mitochondrial p53 may be an important regulator of normal mitochondrial and cellular physiology, potentially exerting tumor suppression activity inside mitochondria. PMID:23966169

Mitochondrial p53 mediates a transcription-independent regulation of cell respiration and interacts with the mitochondrial F₁F0-ATP synthase.

PubMed

Bergeaud, Marie; Mathieu, Lise; Guillaume, Arnaud; Moll, Ute M; Mignotte, Bernard; Le Floch, Nathalie; Vayssière, Jean-Luc; Rincheval, Vincent

2013-09-01

We and others previously reported that endogenous p53 can be located at mitochondria in the absence of stress, suggesting that p53 has a role in the normal physiology of this organelle. The aim of this study was to characterize in unstressed cells the intramitochondrial localization of p53 and identify new partners and functions of p53 in mitochondria. We find that the intramitochondrial pool of p53 is located in the intermembrane space and the matrix. Of note, unstressed HCT116 p53(+/+) cells simultaneously show increased O₂ consumption and decreased mitochondrial superoxide production compared with their p53-null counterpart. This data was confirmed by stable H1299 cell lines expressing low levels of p53 specifically targeted to the matrix. Using immunoprecipitation and mass spectrometry, we identified the oligomycin sensitivity-conferring protein (OSCP), a subunit of the F₁F₀-ATP synthase complex, as a new partner of endogenous p53, specifically interacting with p53 localized in the matrix. Interestingly, this interaction seems implicated in mitochondrial p53 localization. Moreover, p53 localized in the matrix promotes the assembly of F₁F₀-ATP synthase. Taking into account that deregulations of mitochondrial respiration and reactive oxygen species production are tightly linked to cancer development, we suggest that mitochondrial p53 may be an important regulator of normal mitochondrial and cellular physiology, potentially exerting tumor suppression activity inside mitochondria.

Use of Small Angle Neutron Scattering to Study Various Properties of Wool and Mohair Fibres

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

Franklyn, C. B.; Toeroek, Gy.

2011-12-13

To maintain a competitive edge in the wool and mohair industry, a detailed knowledge and understanding of the properties of wool fibres is essential. Standard techniques are used to determine fibre diameter, length and strength; however, properties such as hydroscopicity, lustre and changes in fibre structure following chemical or mechanical treatment are not so well understood. The unique capabilities of small angle neutron scattering to study changes in the supermolecular structure of wool fibres, particularly at the level of the microfibril-matrix complex, have been used to provide previously unknown features of the fibres. The results of these studies are presented.

Development of a scanning time of flight microscope and its application to the study of charge transport in phase separated structured organic semiconductors

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

Paul, Sanjoy; Ellman, Brett, E-mail: bellman@kent.edu; Singh, Gautam

We describe a tool for studying the two-dimensional spatial variation in electronic properties of organic semiconductors: the scanning time-of-flight microscope (STOFm). The STOFm simultaneously measures the transmittance of polarized light and time-of-flight current transients with a pixel size <30 μm, making it especially valuable for studies of the correlations of structure with charge generation and transport in liquid crystalline organic semiconductors (LC OSCs). Adapting a previously developed photopolymerization technique, we characterize the instrument using patterned samples of a LC OSC bounded by a non-semiconducting polymer matrix.

Objective Assessment and Design Improvement of a Staring, Sparse Transducer Array by the Spatial Crosstalk Matrix for 3D Photoacoustic Tomography

PubMed Central

Kosik, Ivan; Raess, Avery

2015-01-01

Accurate reconstruction of 3D photoacoustic (PA) images requires detection of photoacoustic signals from many angles. Several groups have adopted staring ultrasound arrays, but assessment of array performance has been limited. We previously reported on a method to calibrate a 3D PA tomography (PAT) staring array system and analyze system performance using singular value decomposition (SVD). The developed SVD metric, however, was impractical for large system matrices, which are typical of 3D PAT problems. The present study consisted of two main objectives. The first objective aimed to introduce the crosstalk matrix concept to the field of PAT for system design. Figures-of-merit utilized in this study were root mean square error, peak signal-to-noise ratio, mean absolute error, and a three dimensional structural similarity index, which were derived between the normalized spatial crosstalk matrix and the identity matrix. The applicability of this approach for 3D PAT was validated by observing the response of the figures-of-merit in relation to well-understood PAT sampling characteristics (i.e. spatial and temporal sampling rate). The second objective aimed to utilize the figures-of-merit to characterize and improve the performance of a near-spherical staring array design. Transducer arrangement, array radius, and array angular coverage were the design parameters examined. We observed that the performance of a 129-element staring transducer array for 3D PAT could be improved by selection of optimal values of the design parameters. The results suggested that this formulation could be used to objectively characterize 3D PAT system performance and would enable the development of efficient strategies for system design optimization. PMID:25875177

Graft copolymers of ethyl methacrylate on waxy maize starch derivatives as novel excipients for matrix tablets: drug release and fronts movement kinetics.

PubMed

Marinich, J A; Ferrero, C; Jiménez-Castellanos, M R

2012-04-01

A previous paper deals with the physicochemical and technological characterization of novel graft copolymers of ethyl methacrylate (EMA) on waxy maize starch (MS) and hydroxypropylstarch (MHS). The results obtained suggested the potential application of these copolymers as excipients for compressed non-disintegrating matrix tablets. Therefore, the purpose of the present study was to investigate the mechanism governing drug release from matrix systems prepared with the new copolymers and anhydrous theophylline or diltiazem HCl as model drugs with different solubility. The influence of the carbohydrate nature, drying procedure and initial pore network on drug release kinetics was also evaluated. Drug release experiments were performed from free tablets. Radial drug release and fronts movement kinetics were also analysed, and several mathematical models were employed to ascertain the drug release mechanisms. The drug release markedly depends on the drug solubility and the carbohydrate nature but is practically not affected by the drying process and the initial matrix porosity. A faster drug release is observed for matrices containing diltiazem HCl compared with those containing anhydrous theophylline, in accordance with the higher drug solubility and the higher friability of diltiazem matrices. In fact, although diffusion is the prevailing drug release mechanism for all matrices, the erosion mechanism seems to have some contribution in several formulations containing diltiazem. A reduction in the surface exposed to the dissolution medium (radial release studies) leads to a decrease in the drug release rate, but the release mechanism is not essentially modified. The nearly constant erosion front movement confirms the behaviour of these systems as inert matrices where the drugs are released mainly by diffusion through the porous structure. Copyright © 2011 Elsevier B.V. All rights reserved.

Fourier Transformed Infra-Red Imaging of Femoral Neck Bone: Reduced Heterogeneity of Mineral-to-Matrix and Carbonate-to-Phosphate and more Variable Crystallinity in Treatment-Naïve Fracture Cases compared to Fracture-Free Controls

PubMed Central

Gourion-Arsiquaud, Samuel; Lukashova, Lyudmilla; Power, Jon; Loveridge, Nigel; Reeve, Jonathan; Boskey, Adele L.

2012-01-01

After age 60 hip fracture risk strongly increases, but only a fifth of this increase is attributable to reduced mineral density (BMD, measured clinically). Changes in bone quality, specifically bone composition as measured by Fourier Transform Infrared spectroscopic imaging (FTIRI), also contribute to fracture risk. Here, FTIRI was applied to study the femoral neck and provide spatially derived information on its mineral and matrix properties in age-matched fractured and non-fractured bones. Whole femoral neck cross sections, divided into quadrants along the neck’s axis, from 10 women with hip fracture and 10 cadaveric controls were studied using FTIRI and micro-computed Tomography. Although 3-dimensional micro-CT bone mineral densities were similar, the mineral-to-matrix ratio was reduced in the cases of hip fracture, confirming previous reports. New findings were that the FTIRI microscopic variation (heterogeneity) of the mineral-to-matrix ratio was substantially reduced in the fracture group as was the heterogeneity of the carbonate-to-phosphate ratio. Conversely, the heterogeneity of crystallinity was increased. Increased variation of crystallinity was statistically associated with reduced variation of the carbonate-to-phosphate ratio. Anatomical variation in these properties between the different femoral neck quadrants was reduced in the fracture group compared to controls. While our treatment-naïve patients had reduced rather than increased bending resistance, these changes in heterogeneity associated with hip fracture are in another way comparable to the effects of experimental bisphosphonate therapy, which decreases heterogeneity and other indicators of bone’s toughness as a material. PMID:22865771

Fourier transform infrared imaging of femoral neck bone: reduced heterogeneity of mineral-to-matrix and carbonate-to-phosphate and more variable crystallinity in treatment-naive fracture cases compared with fracture-free controls.

PubMed

Gourion-Arsiquaud, Samuel; Lukashova, Lyudmilla; Power, Jon; Loveridge, Nigel; Reeve, Jonathan; Boskey, Adele L

2013-01-01

After the age of 60 years, hip fracture risk strongly increases, but only a fifth of this increase is attributable to reduced bone mineral density (BMD, measured clinically). Changes in bone quality, specifically bone composition as measured by Fourier transform infrared spectroscopic imaging (FTIRI), also contribute to fracture risk. Here, FTIRI was applied to study the femoral neck and provide spatially derived information on its mineral and matrix properties in age-matched fractured and nonfractured bones. Whole femoral neck cross sections, divided into quadrants along the neck's axis, from 10 women with hip fracture and 10 cadaveric controls were studied using FTIRI and micro-computed tomography. Although 3-dimensional micro-CT bone mineral densities were similar, the mineral-to-matrix ratio was reduced in the cases of hip fracture, confirming previous reports. New findings were that the FTIRI microscopic variation (heterogeneity) of the mineral-to-matrix ratio was substantially reduced in the fracture group as was the heterogeneity of the carbonate-to-phosphate ratio. Conversely, the heterogeneity of crystallinity was increased. Increased variation of crystallinity was statistically associated with reduced variation of the carbonate-to-phosphate ratio. Anatomical variation in these properties between the different femoral neck quadrants was reduced in the fracture group compared with controls. Although our treatment-naive patients had reduced rather than increased bending resistance, these changes in heterogeneity associated with hip fracture are in another way comparable to the effects of experimental bisphosphonate therapy, which decreases heterogeneity and other indicators of bone's toughness as a material. Copyright © 2013 American Society for Bone and Mineral Research.

Multi-energy CT based on a prior rank, intensity and sparsity model (PRISM).

PubMed

Gao, Hao; Yu, Hengyong; Osher, Stanley; Wang, Ge

2011-11-01

We propose a compressive sensing approach for multi-energy computed tomography (CT), namely the prior rank, intensity and sparsity model (PRISM). To further compress the multi-energy image for allowing the reconstruction with fewer CT data and less radiation dose, the PRISM models a multi-energy image as the superposition of a low-rank matrix and a sparse matrix (with row dimension in space and column dimension in energy), where the low-rank matrix corresponds to the stationary background over energy that has a low matrix rank, and the sparse matrix represents the rest of distinct spectral features that are often sparse. Distinct from previous methods, the PRISM utilizes the generalized rank, e.g., the matrix rank of tight-frame transform of a multi-energy image, which offers a way to characterize the multi-level and multi-filtered image coherence across the energy spectrum. Besides, the energy-dependent intensity information can be incorporated into the PRISM in terms of the spectral curves for base materials, with which the restoration of the multi-energy image becomes the reconstruction of the energy-independent material composition matrix. In other words, the PRISM utilizes prior knowledge on the generalized rank and sparsity of a multi-energy image, and intensity/spectral characteristics of base materials. Furthermore, we develop an accurate and fast split Bregman method for the PRISM and demonstrate the superior performance of the PRISM relative to several competing methods in simulations.

First Industrial Tests of a Drum Monitor Matrix Correction for the Fissile Mass Measurement in Large Volume Historic Metallic Residues with the Differential Die-away Technique

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

Antoni, R.; Passard, C.; Perot, B.

2015-07-01

The fissile mass in radioactive waste drums filled with compacted metallic residues (spent fuel hulls and nozzles) produced at AREVA La Hague reprocessing plant is measured by neutron interrogation with the Differential Die-away measurement Technique (DDT. In the next years, old hulls and nozzles mixed with Ion-Exchange Resins will be measured. The ion-exchange resins increase neutron moderation in the matrix, compared to the waste measured in the current process. In this context, the Nuclear Measurement Laboratory (NML) of CEA Cadarache has studied a matrix effect correction method, based on a drum monitor ({sup 3}He proportional counter inside the measurement cavity).more » A previous study performed with the NML R and D measurement cell PROMETHEE 6 has shown the feasibility of method, and the capability of MCNP simulations to correctly reproduce experimental data and to assess the performances of the proposed correction. A next step of the study has focused on the performance assessment of the method on the industrial station using numerical simulation. A correlation between the prompt calibration coefficient of the {sup 239}Pu signal and the drum monitor signal was established using the MCNPX computer code and a fractional factorial experimental design composed of matrix parameters representative of the variation range of historical waste. Calculations have showed that the method allows the assay of the fissile mass with an uncertainty within a factor of 2, while the matrix effect without correction ranges on 2 decades. In this paper, we present and discuss the first experimental tests on the industrial ACC measurement system. A calculation vs. experiment benchmark has been achieved by performing dedicated calibration measurement with a representative drum and {sup 235}U samples. The preliminary comparison between calculation and experiment shows a satisfactory agreement for the drum monitor. The final objective of this work is to confirm the reliability of the modeling approach and the industrial feasibility of the method, which will be implemented on the industrial station for the measurement of historical wastes. (authors)« less

Body fluid matrix evaluation on a Roche cobas 8000 system.

PubMed

Owen, William E; Thatcher, Mindy L; Crabtree, Karolyn J; Greer, Ryan W; Strathmann, Frederick G; Straseski, Joely A; Genzen, Jonathan R

2015-09-01

Chemical analysis of body fluids is commonly requested by physicians. Because most commercial FDA-cleared clinical laboratory assays are not validated by diagnostic manufacturers for "non-serum" and "non-plasma" specimens, laboratories may need to complete additional validation studies to comply with regulatory requirements regarding body fluid testing. The objective of this report is to perform recovery studies to evaluate potential body fluid matrix interferences for commonly requested chemistry analytes. Using an IRB-approved protocol, previously collected clinical body fluid specimens (biliary/hepatic, cerebrospinal, dialysate, drain, pancreatic, pericardial, peritoneal, pleural, synovial, and vitreous) were de-identified and frozen (-20°C) until experiments were performed. Recovery studies (spiking with high concentration serum, control, and/or calibrator) were conducted using 10% spiking solution by volume; n=5 specimens per analyte/body fluid investigated. Specimens were tested on a Roche cobas 8000 system (c502, c702, e602, and ISE modules). In all 80 analyte/body fluid combinations investigated (including amylase, total bilirubin, urea nitrogen, carbohydrate antigen 19-9, carcinoembryonic antigen, cholesterol, chloride, creatinine, glucose, potassium, lactate dehydrogenase, lipase, rheumatoid factor, sodium, total protein, triglycerides, and uric acid), the average percent recovery was within predefined acceptable limits (less than ±10% from the calculated ideal recovery). The present study provides evidence against the presence of any systematic matrix interference in the analyte/body fluid combinations investigated on the Roche cobas 8000 system. Such findings support the utility of ongoing body fluid validation initiatives conducted to maintain compliance with regulatory requirements. Copyright © 2015 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

Association of functional MMP-2 gene variant with intracranial aneurysms: case-control genetic association study and meta-analysis.

PubMed

Alg, Varinder S; Ke, Xiayi; Grieve, Joan; Bonner, Stephen; Walsh, Daniel C; Bulters, Diederik; Kitchen, Neil; Houlden, Henry; Werring, David J

2018-01-15

Abnormalities in Matrix Metalloproteinase (MMP) genes, which are important in extracellular matrix (ECM) maintenance and therefore arterial wall integrity are a plausible underlying mechanism of intracranial aneurysm (IA) formation, growth and subsequent rupture. We investigated whether the rs243865 C > T SNP (single nucleotide polymorphism) within the MMP-2 gene (which influences gene transcription) is associated with IA compared to matched controls. We conducted a case-control genetic association study, adjusted for known IA risk factors (smoking and hypertension), in a UK Caucasian population of 1409 patients with intracranial aneurysms (IA), and 1290 matched controls, to determine the association of the rs243865 C > T functional MMP-2 gene SNP with IA (overall, and classified as ruptured and unruptured). We also undertook a meta-analysis of two previous studies examining this SNP. The rs243865 T allele was associated with IA presence in univariate (OR 1.18 [95% CI 1.04-1.33], p = .01) and in multi-variable analyses adjusted for smoking and hypertension status (OR 1.16 [95% CI 1.01-1.35], p = .042). Subgroup analysis demonstrated an association of the rs243865 SNP with ruptured IA (OR 1.18 [95% CI 1.03-1.34] p = .017), but, not unruptured IA (OR 1.17 [95% CI 0.97-1.42], p = .11). Our study demonstrated an association between the functional MMP-2 rs243865 variant and IAs. Our findings suggest a genetic role for altered extracellular matrix integrity in the pathogenesis of IA development and rupture.

pLARmEB: integration of least angle regression with empirical Bayes for multilocus genome-wide association studies.

PubMed

Zhang, J; Feng, J-Y; Ni, Y-L; Wen, Y-J; Niu, Y; Tamba, C L; Yue, C; Song, Q; Zhang, Y-M

2017-06-01

Multilocus genome-wide association studies (GWAS) have become the state-of-the-art procedure to identify quantitative trait nucleotides (QTNs) associated with complex traits. However, implementation of multilocus model in GWAS is still difficult. In this study, we integrated least angle regression with empirical Bayes to perform multilocus GWAS under polygenic background control. We used an algorithm of model transformation that whitened the covariance matrix of the polygenic matrix K and environmental noise. Markers on one chromosome were included simultaneously in a multilocus model and least angle regression was used to select the most potentially associated single-nucleotide polymorphisms (SNPs), whereas the markers on the other chromosomes were used to calculate kinship matrix as polygenic background control. The selected SNPs in multilocus model were further detected for their association with the trait by empirical Bayes and likelihood ratio test. We herein refer to this method as the pLARmEB (polygenic-background-control-based least angle regression plus empirical Bayes). Results from simulation studies showed that pLARmEB was more powerful in QTN detection and more accurate in QTN effect estimation, had less false positive rate and required less computing time than Bayesian hierarchical generalized linear model, efficient mixed model association (EMMA) and least angle regression plus empirical Bayes. pLARmEB, multilocus random-SNP-effect mixed linear model and fast multilocus random-SNP-effect EMMA methods had almost equal power of QTN detection in simulation experiments. However, only pLARmEB identified 48 previously reported genes for 7 flowering time-related traits in Arabidopsis thaliana.