An experimental strategy validated to design cost-effective culture media based on response surface methodology.

PubMed

Navarrete-Bolaños, J L; Téllez-Martínez, M G; Miranda-López, R; Jiménez-Islas, H

2017-07-03

For any fermentation process, the production cost depends on several factors, such as the genetics of the microorganism, the process condition, and the culture medium composition. In this work, a guideline for the design of cost-efficient culture media using a sequential approach based on response surface methodology is described. The procedure was applied to analyze and optimize a culture medium of registered trademark and a base culture medium obtained as a result of the screening analysis from different culture media used to grow the same strain according to the literature. During the experiments, the procedure quantitatively identified an appropriate array of micronutrients to obtain a significant yield and find a minimum number of culture medium ingredients without limiting the process efficiency. The resultant culture medium showed an efficiency that compares favorably with the registered trademark medium at a 95% lower cost as well as reduced the number of ingredients in the base culture medium by 60% without limiting the process efficiency. These results demonstrated that, aside from satisfying the qualitative requirements, an optimum quantity of each constituent is needed to obtain a cost-effective culture medium. Study process variables for optimized culture medium and scaling-up production for the optimal values are desirable.

Demystifying the memory effect: A geometrical approach to understanding speckle correlations

NASA Astrophysics Data System (ADS)

Prunty, Aaron C.; Snieder, Roel K.

2017-05-01

The memory effect has seen a surge of research into its fundamental properties and applications since its discovery by Feng et al. [Phys. Rev. Lett. 61, 834 (1988)]. While the wave trajectories for which the memory effect holds are hidden implicitly in the diffusion probability function [Phys. Rev. B 40, 737 (1989)], the physical intuition of why these trajectories satisfy the memory effect has often been masked by the derivation of the memory correlation function itself. In this paper, we explicitly derive the specific trajectories through a random medium for which the memory effect holds. Our approach shows that the memory effect follows from a simple conservation argument, which imposes geometrical constraints on the random trajectories that contribute to the memory effect. We illustrate the time-domain effects of these geometrical constraints with numerical simulations of pulse transmission through a random medium. The results of our derivation and numerical simulations are consistent with established theory and experimentation.

Systematic approach to thermal leptogenesis

NASA Astrophysics Data System (ADS)

Frossard, T.; Garny, M.; Hohenegger, A.; Kartavtsev, A.; Mitrouskas, D.

2013-04-01

In this work we study thermal leptogenesis using nonequilibrium quantum field theory. Starting from fundamental equations for correlators of the quantum fields we describe the steps necessary to obtain quantum-kinetic equations for quasiparticles. These can easily be compared to conventional results and overcome conceptional problems inherent in the canonical approach. Beyond CP-violating decays we include also those scattering processes which are tightly related to the decays in a consistent approximation of fourth order in the Yukawa couplings. It is demonstrated explicitly how the S-matrix elements for the scattering processes in the conventional approach are related to two- and three-loop contributions to the effective action. We derive effective decay and scattering amplitudes taking medium corrections and thermal masses into account. In this context we also investigate CP-violating Higgs decay within the same formalism. From the kinetic equations we derive rate equations for the lepton asymmetry improved in that they include quantum-statistical effects and medium corrections to the quasiparticle properties.

Responses of Four Adolescent Females to Adolescent Fiction with Strong Female Characters.

ERIC Educational Resources Information Center

Carico, Kathleen M.

A study examined the effects of a reader response approach to literature in which literature is viewed as a medium for exploration and the effects of such an approach on a group of young women. Subjects of the study were four female middle school students, with the adult female researcher as participant observer. Books chosen for…

Transport properties of porous media from the microstructure

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

Torquato, S.

The determination of the effective transport properties of a random porous medium remains a challenging area of research because the properties depend on the microstructure in a highly complex fashion. This paper reviews recent theoretical and experimental progress that we have made on various aspects of this problem. A unified approach is taken to characterize the microstructure and the seemingly disparate properties of the medium.

Ground-state energies and charge radii of medium-mass nuclei in the unitary-model-operator approach

NASA Astrophysics Data System (ADS)

Miyagi, Takayuki; Abe, Takashi; Okamoto, Ryoji; Otsuka, Takaharu

2014-09-01

In nuclear structure theory, one of the most fundamental problems is to understand the nuclear structure based on nuclear forces. This attempt has been enabled due to the progress of the computational power and nuclear many-body approaches. However, it is difficult to apply the first-principle methods to medium-mass region, because calculations demand the huge model space as increasing the number of nucleons. The unitary-model-operator approach (UMOA) is one of the methods which can be applied to medium-mass nuclei. The essential point of the UMOA is to construct the effective Hamiltonian which does not induce the two-particle-two-hole excitations. A many-body problem is reduced to the two-body subsystem problem in an entire many-body system with the two-body effective interaction and one-body potential determined self-consistently. In this presentation, we will report the numerical results of ground-state energies and charge radii of 16O, 40Ca, and 56Ni in the UMOA, and discuss the saturation property by comparing our results with those in the other many-body methods and also experimental data. In nuclear structure theory, one of the most fundamental problems is to understand the nuclear structure based on nuclear forces. This attempt has been enabled due to the progress of the computational power and nuclear many-body approaches. However, it is difficult to apply the first-principle methods to medium-mass region, because calculations demand the huge model space as increasing the number of nucleons. The unitary-model-operator approach (UMOA) is one of the methods which can be applied to medium-mass nuclei. The essential point of the UMOA is to construct the effective Hamiltonian which does not induce the two-particle-two-hole excitations. A many-body problem is reduced to the two-body subsystem problem in an entire many-body system with the two-body effective interaction and one-body potential determined self-consistently. In this presentation, we will report the numerical results of ground-state energies and charge radii of 16O, 40Ca, and 56Ni in the UMOA, and discuss the saturation property by comparing our results with those in the other many-body methods and also experimental data. The part of numerical calculation has been done on the NEC SX8R at RCNP, Osaka University. This work was supported in part by MEXT SPIRE and JICFuS. It was also supported in part by the Program in part for Leading Graduate Schools, MEXT, Japan.

Surface-peaked medium effects in the interaction of nucleons with finite nuclei

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

Aguayo, F. J.; Arellano, H. F.

We investigate the asymptotic separation of the optical model potential for nucleon-nucleus scattering in momentum space, where the potential is split into a medium-independent term and another depending exclusively on the gradient of the density-dependent g matrix. This decomposition confines the medium sensitivity of the nucleon-nucleus coupling to the surface of the nucleus. We examine this feature in the context of proton-nucleus scattering at beam energies between 30 and 100 MeV and find that the pn coupling accounts for most of this sensitivity. Additionally, based on this general structure of the optical potential we are able to treat both, themore » medium dependence of the effective interaction and the full mixed density as described by single-particle shell models. The calculated scattering observables agree within 10% with those obtained by Arellano, Brieva, and Love in their momentum-space g-folding approach.« less

Resilience: A Meta-Analytic Approach

ERIC Educational Resources Information Center

Lee, Ji Hee; Nam, Suk Kyung; Kim, A-Reum; Kim, Boram; Lee, Min Young; Lee, Sang Min

2013-01-01

This study investigated the relationship between psychological resilience and its relevant variables by using a meta-analytic method. The results indicated that the largest effect on resilience was found to stem from the protective factors, a medium effect from risk factors, and the smallest effect from demographic factors. (Contains 4 tables.)

Transport of photons produced by lightning in clouds

NASA Technical Reports Server (NTRS)

Solakiewicz, Richard

1991-01-01

The optical effects of the light produced by lightning are of interest to atmospheric scientists for a number of reasons. Two techniques are mentioned which are used to explain the nature of these effects: Monte Carlo simulation; and an equivalent medium approach. In the Monte Carlo approach, paths of individual photons are simulated; a photon is said to be scattered if it escapes the cloud, otherwise it is absorbed. In the equivalent medium approach, the cloud is replaced by a single obstacle whose properties are specified by bulk parameters obtained by methods due to Twersky. Herein, Boltzmann transport theory is used to obtain photon intensities. The photons are treated like a Lorentz gas. Only elastic scattering is considered and gravitational effects are neglected. Water droplets comprising a cuboidal cloud are assumed to be spherical and homogeneous. Furthermore, it is assumed that the distribution of droplets in the cloud is uniform and that scattering by air molecules is neglible. The time dependence and five dimensional nature of this problem make it particularly difficult; neither analytic nor numerical solutions are known.

Mitigation of the inhibitory effect of soap by magnesium salt treatment of crude glycerol--a novel approach for enhanced biohydrogen production from the biodiesel industry waste.

PubMed

Sarma, Saurabh Jyoti; Brar, Satinder Kaur; Le Bihan, Yann; Buelna, Gerardo; Soccol, Carlos Ricardo

2014-01-01

Owing to its inhibitory effect on microbial growth, soap present in crude glycerol (CG) is a concern in biological valorization of the biodiesel manufacturing waste. By salting out strategy, up to 42% of the soap has been removed and the approach has beneficial effect on H2 production; however, removal of more than 7% of the soap was found to be inhibitory. Actually, soap is utilized as a co-substrate and due to removal; the carbon-nitrogen ratio of the medium might have decreased to reduce the production. Alternatively, without changing the carbon-nitrogen ratio of CG, MgSO4 treatment can convert the soap to its inactive form (scum). The approach was found to increase the H2 production rate (33.82%), cumulative H2 production (34.70%) as well as glycerol utilization (nearly 2.5-folds). Additionally, the treatment can increase the Mg (a nutrient) content of the medium from 0.57 ppm to 201.92 ppm. Copyright © 2013 Elsevier Ltd. All rights reserved.

Nonequilibrium Statistical Operator Method and Generalized Kinetic Equations

NASA Astrophysics Data System (ADS)

Kuzemsky, A. L.

2018-01-01

We consider some principal problems of nonequilibrium statistical thermodynamics in the framework of the Zubarev nonequilibrium statistical operator approach. We present a brief comparative analysis of some approaches to describing irreversible processes based on the concept of nonequilibrium Gibbs ensembles and their applicability to describing nonequilibrium processes. We discuss the derivation of generalized kinetic equations for a system in a heat bath. We obtain and analyze a damped Schrödinger-type equation for a dynamical system in a heat bath. We study the dynamical behavior of a particle in a medium taking the dissipation effects into account. We consider the scattering problem for neutrons in a nonequilibrium medium and derive a generalized Van Hove formula. We show that the nonequilibrium statistical operator method is an effective, convenient tool for describing irreversible processes in condensed matter.

Eigenvalue approach to coupled thermoelasticity in a rotating isotropic medium

NASA Astrophysics Data System (ADS)

Bayones, F. S.; Abd-Alla, A. M.

2018-03-01

In this paper the linear theory of the thermoelasticity has been employed to study the effect of the rotation in a thermoelastic half-space containing heat source on the boundary of the half-space. It is assumed that the medium under consideration is traction free, homogeneous, isotropic, as well as without energy dissipation. The normal mode analysis has been applied in the basic equations of coupled thermoelasticity and finally the resulting equations are written in the form of a vector- matrix differential equation which is then solved by eigenvalue approach. Numerical results for the displacement components, stresses, and temperature are given and illustrated graphically. Comparison was made with the results obtained in the presence and absence of the rotation. The results indicate that the effect of rotation, non-dimensional thermal wave and time are very pronounced.

Photobiomodulation of distinct lineages of human dermal fibroblasts: a rational approach towards the selection of effective light parameters for skin rejuvenation and wound healing

NASA Astrophysics Data System (ADS)

Mignon, Charles; Uzunbajakava, Natallia E.; Raafs, Bianca; Moolenaar, Mitchel; Botchkareva, Natalia V.; Tobin, Desmond J.

2016-03-01

Distinct lineages of human dermal fibroblasts play complementary roles in skin rejuvenation and wound healing, which makes them a target of phototherapy. However, knowledge about differential responses of specific cell lineages to different light parameters and moreover the actual molecular targets remain to be unravelled. The goal of this study was to investigate the impact of a range of parameters of light on the metabolic activity, collagen production, and cell migration of distinct lineages of human dermal fibroblasts. A rational approach was used to identify parameters with high therapeutic potential. Fibroblasts exhibited both inhibitory and cytotoxic change when exposed to a high dose of blue and cyan light in tissue culture medium containing photo-reactive species, but were stimulated by high dose red and near infrared light. Cytotoxic effects were eliminated by refreshing the medium after light exposure by removing potential ROS formed by extracellular photo-reactive species. Importantly, distinct lineages of fibroblasts demonstrated opposite responses to low dose blue light treatment when refreshing the medium after exposure. Low dose blue light treatment also significantly increased collagen production by papillary fibroblasts; high dose significantly retarded closure of the scratch wound without signs of cytotoxicity, and this is likely to have involved effects on both cell migration and proliferation. We recommend careful selection of fibroblast subpopulations and their culture conditions, a systematic approach in choosing and translating treatment parameters, and pursuit of fundamental research on identification of photoreceptors and triggered molecular pathways, while seeking effective parameters to address different stages of skin rejuvenation and wound healing.

Counterbalancing hydrodynamic sample distortion effects increases resolution of free-flow zone electrophoresis.

PubMed

Weber, G; Bauer, J

1998-06-01

On fractionation of highly heterogeneous protein mixtures, optimal resolution was achieved by forcing proteins to migrate through a preestablished pH gradient, until they entered a medium with a pH similar but not equal to their pIs. For this purpose, up to seven different media were pumped through the electrophoresis chamber so that they were flowing adjacently to each other, forming a pH gradient declining stepwise from the cathode to the anode. This gradient had a sufficiently strong band-focusing effect to counterbalance sample distortion effects of the flowing medium as proteins approached their isoelectric medium closer than 0.5 pH units. Continuous free-flow zone electrophoresis (FFZE) with high throughput capability was applicable if proteins did not precipitate or aggregate in these media. If components of heterogeneous protein mixtures had already started to precipitate or aggregate, in a medium with a pH exceeding their pI by more than 0.5 pH units, the application of interval modus and media forming flat pH gradients appeared advantageous.

Novel Aspects of Evolution of the Stokes Parameters for an Electromagnetic Wave in Anisotropic Media

NASA Astrophysics Data System (ADS)

Botet, R.; Kuratsuji, H.; Seto, R.

2006-08-01

Polarization of a plane electromagnetic wave travelling through a medium is studied in the slowly-varying field envelope approximation. It is shown that the problem is identical to the 4-momentum evolution of a negatively-charged massless relativistic particle in an electromagnetic field. The approach is exemplified by the resonant oscillations of circular polarization in a medium embedded in a static magnetic field and a modulated electric field. The effect of dissipation in the medium is discussed. It is shown that the Rabi oscillations are stable below a threshold depending on the absorption coefficient. Above it, oscillations disappear.

Effects of age and brightness contrast on perception of the Wundt-Hering illusion.

PubMed

Astor-Stetson, E; Purnell, T G

1990-10-01

Susceptibility to the Wundt-Hering illusion was studied as a function of age and contrast. Preschoolers, third-graders and college students were shown light-grey, medium-grey, and black Wundt-Hering figures on white ground. Pre-schoolers were most susceptible to the illusion, differing from third graders in the medium and high contrast conditions and from college students in all contrast conditions. Low contrast figures resulted in significantly less distortion than did high contrast figures for the preschoolers. The significant interaction of age and contrast effects highlights the importance of a developmental approach to the study of illusions.

Application of the Maxwell-Wagner-Hanai effective medium theory to the analysis of the interfacial polarization relaxations in conducting composite films

NASA Astrophysics Data System (ADS)

J-P Adohi, B.; Vanga Bouanga, C.; Fatyeyeva, K.; Tabellout, M.

2009-01-01

A new approach to explain the interfacial polarization phenomenon in conducting composite films is proposed. HCl-doped poly(ethylene terephthalate) (PET) and polyamide-6 (PA-6) matrices with embedded polyaniline (PANI) particles as filler were investigated and analysed, combining dielectric spectroscopy and AFM electrical images with the effective medium theory analysis. Up to three relaxation peaks attributed to the interfacial polarization phenomena were detected in the studied frequency range (0.1 Hz-1 MHz). The AFM electrical images revealed that the doped PA-6/PANI composite can be modelled as a single-type particle medium and the PET/PANI one as a two-type particle medium. A simple dielectric loss expression was derived from the Maxwell-Wagner-Hanai mixture equation and was applied to the experimental data to identify the interfaces involved in each of the relaxation peaks. The parameter values (permittivity, conductivity, volume fraction of the PANI particles) were found to agree well with the measured one, hence validating the models.

Dissociation of heavy quarkonium in hot QCD medium in a quasiparticle model

NASA Astrophysics Data System (ADS)

Agotiya, Vineet Kumar; Chandra, Vinod; Jamal, M. Yousuf; Nilima, Indrani

2016-11-01

Following a recent work on the effective description of the equations of state for hot QCD obtained from a hard thermal loop expression for the gluon self-energy, in terms of the quasigluons and quasiquarks and antiquarks with respective effective fugacities, the dissociation process of heavy quarkonium in hot QCD medium has been investigated. This has been done by investigating the medium modification to a heavy quark potential. The medium-modified potential has a quite different form (a long-range Coulomb tail in addition to the usual Yukawa term) in contrast to the usual picture of Debye screening. The flavor dependence binding energies of the heavy quarkonia states and the dissociation temperature have been obtained by employing the Debye mass for pure gluonic and full QCD case computed employing the quasiparticle picture. Thus, estimated dissociation patterns of the charmonium and bottomonium states, considering Debye mass from different approaches in the pure gluonic case and full QCD, have shown good agreement with the other potential model studies.

Estimation of Random Medium Parameters from 2D Post-Stack Seismic Data and Its Application in Seismic Inversion

NASA Astrophysics Data System (ADS)

Yang, X.; Zhu, P.; Gu, Y.; Xu, Z.

2015-12-01

Small scale heterogeneities of subsurface medium can be characterized conveniently and effectively using a few simple random medium parameters (RMP), such as autocorrelation length, angle and roughness factor, etc. The estimation of these parameters is significant in both oil reservoir prediction and metallic mine exploration. Poor accuracy and low stability existed in current estimation approaches limit the application of random medium theory in seismic exploration. This study focuses on improving the accuracy and stability of RMP estimation from post-stacked seismic data and its application in the seismic inversion. Experiment and theory analysis indicate that, although the autocorrelation of random medium is related to those of corresponding post-stacked seismic data, the relationship is obviously affected by the seismic dominant frequency, the autocorrelation length, roughness factor and so on. Also the error of calculation of autocorrelation in the case of finite and discrete model decreases the accuracy. In order to improve the precision of estimation of RMP, we design two improved approaches. Firstly, we apply region growing algorithm, which often used in image processing, to reduce the influence of noise in the autocorrelation calculated by the power spectrum method. Secondly, the orientation of autocorrelation is used as a new constraint in the estimation algorithm. The numerical experiments proved that it is feasible. In addition, in post-stack seismic inversion of random medium, the estimated RMP may be used to constrain inverse procedure and to construct the initial model. The experiment results indicate that taking inversed model as random medium and using relatively accurate estimated RMP to construct initial model can get better inversion result, which contained more details conformed to the actual underground medium.

Current information technology needs of small to medium sized apparel manufacturers and contractors

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

Wimple, C., LLNL

1998-04-01

This report documents recent efforts of the American Textile Partnership (AMTEX{sup TM}) Demand Activated Manufacturing Architecture (DAMA) Project to identify opportunities for cost effective enhanced information technology use by small to medium sized apparel manufacturers and contractors. Background on the AMTEX/DAMA project and objectives for the specific DAMA Small and Medium Enterprise (SME) effort are discussed in this section. The approach used to gather information about current opportunities or needs is outlined in Section 2 Approach, and relevant findings are identified and a brief analysis of the information gathered is presented in Section 3 Findings. Recommendations based on the analysis,more » are offered in Section 4 Recommendations, and plans are suggested for DAMA follow-on in Section 5 Future Plans. Trip reports for each of the companies visited are contained in Appendix E - Company Trip Reports. These individual reports contain the data upon which the analysis presented in Section 3 Findings is based.« less

Meta-Analysis of the Reasoned Action Approach (RAA) to Understanding Health Behaviors.

PubMed

McEachan, Rosemary; Taylor, Natalie; Harrison, Reema; Lawton, Rebecca; Gardner, Peter; Conner, Mark

2016-08-01

Reasoned action approach (RAA) includes subcomponents of attitude (experiential/instrumental), perceived norm (injunctive/descriptive), and perceived behavioral control (capacity/autonomy) to predict intention and behavior. To provide a meta-analysis of the RAA for health behaviors focusing on comparing the pairs of RAA subcomponents and differences between health protection and health-risk behaviors. The present research reports a meta-analysis of correlational tests of RAA subcomponents, examination of moderators, and combined effects of subcomponents on intention and behavior. Regressions were used to predict intention and behavior based on data from studies measuring all variables. Capacity and experiential attitude had large, and other constructs had small-medium-sized correlations with intention; all constructs except autonomy were significant independent predictors of intention in regressions. Intention, capacity, and experiential attitude had medium-large, and other constructs had small-medium-sized correlations with behavior; intention, capacity, experiential attitude, and descriptive norm were significant independent predictors of behavior in regressions. The RAA subcomponents have utility in predicting and understanding health behaviors.

Flotation removal of the microalga Nannochloropsis sp. using Moringa protein-oil emulsion: A novel green approach.

PubMed

Kandasamy, Ganesan; Shaleh, Sitti Raehanah Muhamad

2018-01-01

A new approach to recover microalgae from aqueous medium using a bio-flotation method is reported. The method involves utilizing a Moringa protein extract - oil emulsion (MPOE) for flotation removal of Nannochloropsis sp. The effect of various factors has been assessed using this method, including operating parameters such as pH, MPOE dose, algae concentration and mixing time. A maximum flotation efficiency of 86.5% was achieved without changing the pH condition of algal medium. Moreover, zeta potential analysis showed a marked difference in the zeta potential values when increase the MPOE dose concentration. An optimum condition of MPOE dosage of 50ml/L, pH 8, mixing time 4min, and a flotation efficiency of greater than 86% was accomplished. The morphology of algal flocs produced by protein-oil emulsion flocculant were characterized by microscopy. This flotation method is not only simple, but also an efficient method for harvesting microalgae from culture medium. Copyright © 2017 Elsevier Ltd. All rights reserved.

Improving English Language Learners' Academic Writing: A Multi-Strategy Approach to a Multi-Dimensional Challenge

ERIC Educational Resources Information Center

Marulanda Ángel, Nora Lucía; Martínez García, Juan Manuel

2017-01-01

The demands of the academic field and the constraints students have while learning how to write appropriately call for better approaches to teach academic writing. This research study examines the effect of a multifaceted academic writing module on pre-service teachers' composition skills in an English teacher preparation program at a medium sized…

Chiral magnetic currents with QGP medium response in heavy-ion collisions at RHIC and LHC energies

NASA Astrophysics Data System (ADS)

She, Duan; Feng, Sheng-Qin; Zhong, Yang; Yin, Zhong-Bao

2018-03-01

We calculate the electromagnetic current with a more realistic approach in the RHIC and LHC energy regions in the article. We take the partons formation time as the initial time of the magnetic field response of QGP medium. The maximum electromagnetic current and the time-integrated current are two important characteristics of the chiral magnetic effect (CME), which can characterize the intensity and duration of fluctuations of CME. We consider the finite frequency response of CME to a time-varying magnetic field, find a significant impact from QGP medium feedback, and estimate the generated electromagnetic current as a function of time, beam energy and impact parameter.

Proton-Nucleus Total Cross Sections in Coupled-Channel Approach

NASA Technical Reports Server (NTRS)

Tripathi, R. K.; Wilson, John W.; Cucinotta, Francis A.

2000-01-01

Recently, nucleon-nucleon (N-N) cross sections in the medium have been extracted directly from experiment. The in-medium N-N cross sections form the basic ingredients of several heavy-ion scattering approaches including the coupled-channel approach developed at the Langley Research Center. In the present study the ratio of the real to the imaginary part of the two-body scattering amplitude in the medium was investigated. These ratios are used in combination with the in-medium N-N cross sections to calculate total proton-nucleus cross sections. The agreement is excellent with the available experimental data. These cross sections are needed for the radiation risk assessment of space missions.

A Novel Approach for Controlling the Band Formation in Medium Mn Steels

NASA Astrophysics Data System (ADS)

Farahani, H.; Xu, W.; van der Zwaag, S.

2018-06-01

Formation of the microstructural ferrite/pearlite bands in medium Mn steels is an undesirable phenomenon commonly addressed through fast cooling treatments. In this study, a novel approach using the cyclic partial phase transformation concept is applied successfully to prevent microstructural band formation in a micro-chemically banded Fe-C-Mn-Si steel. The effectiveness of the new approach is assessed using the ASTM E1268-01 standard. The cyclic intercritical treatments lead to formation of isotropic microstructures even for cooling rates far below the critical one determined in conventional continuous cooling. In contrast, isothermal intercritical experiments have no effect on the critical cooling rate to suppress microstructural band formation. The origin of the suppression of band formation either by means of fast cooling or a cyclic partial phase transformation is investigated in detail. Theoretical modeling and microstructural observations confirm that band formation is suppressed only if the intercritical annealing treatment leads to partial reversion of the austenite-ferrite interfaces. The resulting interfacial Mn enrichment is responsible for suppression of the band formation upon final cooling at low cooling rates.

A Novel Approach for Controlling the Band Formation in Medium Mn Steels

NASA Astrophysics Data System (ADS)

Farahani, H.; Xu, W.; van der Zwaag, S.

2018-03-01

Formation of the microstructural ferrite/pearlite bands in medium Mn steels is an undesirable phenomenon commonly addressed through fast cooling treatments. In this study, a novel approach using the cyclic partial phase transformation concept is applied successfully to prevent microstructural band formation in a micro-chemically banded Fe-C-Mn-Si steel. The effectiveness of the new approach is assessed using the ASTM E1268-01 standard. The cyclic intercritical treatments lead to formation of isotropic microstructures even for cooling rates far below the critical one determined in conventional continuous cooling. In contrast, isothermal intercritical experiments have no effect on the critical cooling rate to suppress microstructural band formation. The origin of the suppression of band formation either by means of fast cooling or a cyclic partial phase transformation is investigated in detail. Theoretical modeling and microstructural observations confirm that band formation is suppressed only if the intercritical annealing treatment leads to partial reversion of the austenite-ferrite interfaces. The resulting interfacial Mn enrichment is responsible for suppression of the band formation upon final cooling at low cooling rates.

Principles and approach to developing mammalian cell culture media for high cell density perfusion process leveraging established fed-batch media.

PubMed

Lin, Henry; Leighty, Robert Woodrow; Godfrey, Scott; Wang, Samantha Boran

2017-07-01

Perfusion medium was successfully developed based on our fed-batch platform basal and feed media. A systematic development approach was undertaken by first optimizing the ratios of fed-batch basal and feed media followed by targeted removal of unnecessary and redundant components. With this reduction in components, the medium could then be further concentrated by 2× to increase medium depth. The medium osmolality was also optimized where we found ∼360 mOsm/kg was desirable resulting in a residual culture osmolality of ∼300 mOsm/kg for our cell lines. Further building on this, the amino acids Q, E, N, and D were rebalanced to reduce lactate and ammonium levels, and increase the cell-specific productivity without compromising on cell viability while leaving viable cell density largely unaffected. Further modifications were also made by increasing certain important vitamin and lipid concentrations, while eliminating other unnecessary vitamins. Overall, an effective perfusion medium was developed with all components remaining in the formulation understood to be important and their concentrations increased to improve medium depth. The critical cell-specific perfusion rate using this medium was then established for a cell line of interest to be 0.075 nL/cell-day yielding 1.2 g/L-day at steady state. This perfusion process was then successfully scaled up to a 100 L single-use bioreactor with an ATF6 demonstrating similar performance as a 2 L bioreactor with an ATF2. Large volume handling challenges in our fed-batch facility were overcome by developing a liquid medium version of the powder medium product contained in custom totes for plug-and-play use with the bioreactor. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:891-901, 2017. © 2017 American Institute of Chemical Engineers.

Proton-Nucleus Elastic Cross Sections Using Two-Body In-Medium Scattering Amplitudes

NASA Technical Reports Server (NTRS)

Tripathi, R. K.; Wilson, John W.; Cucinotta, Francis A.

2001-01-01

Recently, a method was developed of extracting nucleon-nucleon (NN) cross sections in the medium directly from experiment. The in-medium NN cross sections form the basic ingredients of several heavy-ion scattering approaches including the coupled-channel approach developed at the Langley Research Center. The ratio of the real to the imaginary part of the two-body scattering amplitude in the medium was investigated. These ratios are used in combination with the in-medium NN cross sections to calculate elastic proton-nucleus cross sections. The agreement is excellent with the available experimental data. These cross sections are needed for the radiation risk assessment of space missions.

In-medium pseudoscalar D/B mesons and charmonium decay width

NASA Astrophysics Data System (ADS)

Chhabra, Rahul; Kumar, Arvind

2017-05-01

Using QCD sum rules and the chiral SU(3) model, we investigate the effect of temperature, density, strangeness fraction and isospin asymmetric parameter on the shift in masses and decay constants of the pseudoscalar D and B meson in the hadronic medium, which consist of nucleons and hyperons. The in-medium properties of D and B mesons within the QCD sum rule approach depend upon the quark and gluon condensates. In the chiral SU(3) model, quark and gluon condensates are introduced through the explicit symmetry breaking term and the trace anomaly property of the QCD, respectively and are written in terms of the scalar fields σ, ζ, δ and χ. Hence, through medium modification of σ, ζ, δ and χ fields, we obtain the medium-modified masses and decay constants of D and B mesons. As an application, using {}3P0 model, we calculate the in-medium decay width of the higher charmonium states ψ(3686), ψ(3770) and χ(3556) to the D\\bar{D} pairs, considering the in-medium mass of D mesons. These results may be important to understand the possible outcomes of the high-energy physics experiments, e.g., CBM and PANDA at GSI, Germany.

Effects of ethanol on red blood cell rheological behavior.

PubMed

Rabai, M; Detterich, J A; Wenby, R B; Toth, K; Meiselman, H J

2014-01-01

Consumption of red wine is associated with a decreased risk of several cardiovascular diseases (e.g., coronary artery disease, stroke), but unfortunately literature reports regarding ethanol's effects on hemorheological parameters are not concordant. In the present study, red blood cell (RBC) deformability was tested via laser ektacytometry (LORCA, 0.3-30 Pa) using two approaches: 1) addition of ethanol to whole blood at 0.25%-2% followed by incubation and testing in ethanol-free LORCA medium; 2) addition of ethanol to the LORCA medium at 0.25%-6% then testing untreated native RBC in these media. The effects of ethanol on deformability for oxidatively stressed RBC were investigated as were changes of RBC aggregation (Myrenne Aggregometer) for cells in autologous plasma or 3% 70 kDa dextran. Significant dose-related increases of RBC deformability were observed at 0.25% (p < 0.05) and higher concentrations only if ethanol was in the LORCA medium; no changes occurred for cells previously incubated with ethanol then tested in ethanol-free medium. The impaired deformability of cells pre-exposed to oxidative stress was improved only if ethanol was in the LORCA medium. RBC aggregation decreased with concentration at 0.25% and higher for cells in both autologous plasma and dextran 70. Our results indicate that ethanol reversibly improves erythrocyte deformability and irreversibly decreases erythrocyte aggregation; the relevance of these results to the health benefits of moderate wine consumption require further investigation.

Stem cells from human exfoliated deciduous teeth differentiate toward neural cells in a medium dynamically cultured with Schwann cells in a series of polydimethylsiloxanes scaffolds

NASA Astrophysics Data System (ADS)

Su, Wen-Ta; Pan, Yu-Jing

2016-08-01

Objective. Schwann cells (SCs) are primary structural and functional cells in the peripheral nervous system. These cells play a crucial role in peripheral nerve regeneration by releasing neurotrophic factors. This study evaluated the neural differentiation potential effects of stem cells from human exfoliated deciduous teeth (SHEDs) in a rat Schwann cell (RSC) culture medium. Approach. SHEDs and RSCs were individually cultured on a polydimethylsiloxane (PDMS) scaffold, and the effects of the RSC medium on the SHEDs differentiation between static and dynamic cultures were compared. Main results. Results demonstrated that the SHED cells differentiated by the RSC cultured medium in the static culture formed neurospheres after 7 days at the earliest, and SHED cells formed neurospheres within 3 days in the dynamic culture. These results confirm that the RSC culture medium can induce neurospheres formation, the speed of formation and the number of neurospheres (19.16 folds high) in a dynamic culture was superior to the static culture for 3 days culture. The SHED-derived spheres were further incubated in the RSCs culture medium, these neurospheres continuously differentiated into neurons and neuroglial cells. Immunofluorescent staining and RT-PCR revealed nestin, β-III tubulin, GFAP, and γ-enolase of neural markers on the differentiated cells. Significance. These results indicated that the RSC culture medium can induce the neural differentiation of SHED cells, and can be used as a new therapeutic tool to repair nerve damage.

A functional renormalization method for wave propagation in random media

NASA Astrophysics Data System (ADS)

Lamagna, Federico; Calzetta, Esteban

2017-08-01

We develop the exact renormalization group approach as a way to evaluate the effective speed of the propagation of a scalar wave in a medium with random inhomogeneities. We use the Martin-Siggia-Rose formalism to translate the problem into a non equilibrium field theory one, and then consider a sequence of models with a progressively lower infrared cutoff; in the limit where the cutoff is removed we recover the problem of interest. As a test of the formalism, we compute the effective dielectric constant of an homogeneous medium interspersed with randomly located, interpenetrating bubbles. A simple approximation to the renormalization group equations turns out to be equivalent to a self-consistent two-loops evaluation of the effective dielectric constant.

Traffic Adaptive Energy Efficient and Low Latency Medium Access Control for Wireless Sensor Networks

NASA Astrophysics Data System (ADS)

Yadav, Rajesh; Varma, Shirshu; Malaviya, N.

2008-05-01

Medium access control for wireless sensor networks has been a very active research area in the recent years. The traditional wireless medium access control protocol such as IEEE 802.11 is not suitable for the sensor network application because these are battery powered. The recharging of these sensor nodes is expensive and also not possible. The most of the literature in the medium access for the sensor network focuses on the energy efficiency. The proposed MAC protocol solves the energy inefficiency caused by idle listening, control packet overhead and overhearing taking nodes latency into consideration based on the network traffic. Simulation experiments have been performed to demonstrate the effectiveness of the proposed approach. The validation of the simulation results of the proposed MAC has been done by comparing it with the analytical model. This protocol has been simulated in Network Simulator ns-2.

Overview of LIDS Docking and Berthing System Seals

NASA Technical Reports Server (NTRS)

Daniels, Christopher C.; Dunlap, Patrick H., Jr.; deGroh, Henry C., III; Steinetz, Bruce M.; Oswald, Jay J.; Smith, Ian

2007-01-01

This viewgraph presentation describes the Low Impact Docking System (LIDS) docking and berthing system seals. The contents include: 1) Description of the Application: Low Impact Docking System (LIDS); 2) LIDS Seal Locations: Vehicle Undocked (Hatch Closed); 3) LIDS Seal Locations: Mechanical Pass Thru; 4) LIDS Seal Locations: Electrical and Pyro Connectors; 5) LIDS Seal Locations: Vehicle Docked (Hatches Open); 6) LIDS Seal Locations: Main Interface Seal; 7) Main Interface Seal Challenges and Specifications; 8) Approach; 9) Seal Concepts Under Development/Evaluation; 10) Elastomer Material Evaluations; 11) Evaluation of Relevant Seal Properties; 12) Medium-Scale (12") Gask-O-Seal Compression Tests; 13) Medium-Scale Compression Results; 14) Adhesion Forces of Elliptical Top Gask-o-seals; 15) Medium-Scale Seals; 16) Medium-Scale Leakage Results: Effect of Configuration; 17) Full Scale LIDS Seal Test Rig Development; 18) Materials International Space Station Experiment (MISSE 6A and 6B); and 19) Schedule.

Nonlocality and particle-clustering effects on the optical response of composite materials with metallic nanoparticles

NASA Astrophysics Data System (ADS)

Chen, C. W.; Chung, H. Y.; Chiang, H.-P.; Lu, J. Y.; Chang, R.; Tsai, D. P.; Leung, P. T.

2010-10-01

The optical properties of composites with metallic nanoparticles are studied, taking into account the effects due to the nonlocal dielectric response of the metal and the coalescing of the particles to form clusters. An approach based on various effective medium theories is followed, and the modeling results are compared with those from the cases with local response and particles randomly distributed through the host medium. Possible observations of our modeling results are illustrated via a calculation of the transmission of light through a thin film made of these materials. It is found that the nonlocal effects are particularly significant when the particles coalesce, leading to blue-shifted resonances and slightly lower values in the dielectric functions. The dependence of these effects on the volume fraction and fractal dimension of the metal clusters is studied in detail.

Reflectivity of a disordered monolayer estimated by graded refractive index and scattering models.

PubMed

Diamant, Ruth; Garcí-Valenzuela, Augusto; Fernández-Guasti, Manuel

2012-09-01

Reflectivity of a random monolayer, consisting of transparent spherical particles, is estimated using a graded refractive index model, an effective medium approach, and two scattering models. Two cases, a self-standing film and one with a substrate, are considered. Neither the surrounding medium nor the substrate are absorbing materials. Results at normal incidence, with different particle sizes, covering ratios and refractive indexes, are compared. The purpose of this work is to find under which circumstances, for reflectivity at normal incidence, a particle monolayer behaves as a graded refractive index film.

Metal-coated magnetic nanoparticles in an optically active medium: A nonreciprocal metamaterial

NASA Astrophysics Data System (ADS)

Christofi, Aristi; Stefanou, Nikolaos

2018-03-01

We report on the optical response of a nonreciprocal bianisotropic metamaterial, consisting of spherical, metal-coated magnetic nanoparticles embedded in an optically active medium, thus combining gyrotropy, plasmonic resonances, and chirality in a versatile design. The corresponding effective medium is deduced by an appropriate two-step generalized Maxwell-Garnett homogenization scheme. The associated photonic band structure and transmission spectra are obtained through a six-vector formulation of Maxwell equations, which provides an efficient framework for general bianisotropic structures going beyond existing approaches that involve cumbersome nonlinear eigenvalue problems. Our results, analyzed and discussed in the light of group theory, provide evidence that the proposed metamaterial exhibits some remarkable frequency-tunable properties, such as strong, plasmon-enhanced nonreciprocal polarization azimuth rotation and magnetochiral dichroism.

Effects of a blended learning approach on student outcomes in a graduate-level public health course.

PubMed

Kiviniemi, Marc T

2014-03-11

Blended learning approaches, in which in-person and online course components are combined in a single course, are rapidly increasing in health sciences education. Evidence for the relative effectiveness of blended learning versus more traditional course approaches is mixed. The impact of a blended learning approach on student learning in a graduate-level public health course was examined using a quasi-experimental, non-equivalent control group design. Exam scores and course point total data from a baseline, "traditional" approach semester (n = 28) was compared to that from a semester utilizing a blended learning approach (n = 38). In addition, student evaluations of the blended learning approach were evaluated. There was a statistically significant increase in student performance under the blended learning approach (final course point total d = 0.57; a medium effect size), even after accounting for previous academic performance. Moreover, student evaluations of the blended approach were very positive and the majority of students (83%) preferred the blended learning approach. Blended learning approaches may be an effective means of optimizing student learning and improving student performance in health sciences courses.

Green Chemistry by Nano-Catalysis

EPA Science Inventory

The approach of using MW technique with nano-catalysis and benign aqueous reaction medium can offer an extraordinary synergistic effect with greater potential than these three individual components in isolation. To illustrate the ‘‘proof-of-concept’’ of this “Green and Sustainabl...

Mechanical Strain Measurement from Coda Wave Interferometry

NASA Astrophysics Data System (ADS)

Azzola, J.; Schmittbuhl, J.; Zigone, D.; Masson, F.; Magnenet, V.

2017-12-01

Coda Wave Interferometry (CWI) aims at tracking small changes in solid materials like rocks where elastic waves are diffusing. They are intensively sampling the medium, making the technique much more sensitive than those relying on direct wave arrivals. Application of CWI to ambient seismic noise has found a large range of applications over the past years like for multiscale imaging but also for monitoring complex structures such as regional faults or reservoirs (Lehujeur et al., 2015). Physically, observed changes are typically interpreted as small variations of seismic velocities. However, this interpretation remains questionable. Here, a specific focus is put on the influence of the elastic deformation of the medium on CWI measurements. The goal of the present work is to show from a direct numerical and experimental modeling that deformation signal also exists in CWI measurements which might provide new outcomes for the technique.For this purpose, we model seismic wave propagation within a diffusive medium using a spectral element approach (SPECFEM2D) during an elastic deformation of the medium. The mechanical behavior is obtained from a finite element approach (Code ASTER) keeping the mesh grid of the sample constant during the whole procedure to limit numerical artifacts. The CWI of the late wave arrivals in the synthetic seismograms is performed using both a stretching technique in the time domain and a frequency cross-correlation method. Both show that the elastic deformation of the scatters is fully correlated with time shifts of the CWI differently from an acoustoelastic effect. As an illustration, the modeled sample is chosen as an effective medium aiming to mechanically and acoustically reproduce a typical granitic reservoir rock.Our numerical approach is compared to experimental results where multi-scattering of an acoustic wave through a perforated loaded Au4G (Dural) plate is performed at laboratory scale. Experimental and numerical results of the strain influence on CWI are shown to be consistent.Lehujeur, M., J. Vergne, J. Schmittbuhl, and A. Maggi. Characterization of ambient seismic noise near a deep geothermal reservoir and implications for interferometric methods: a case study in northern alsace, france. Geothermal Energy, 3(1):1-17, 2015.

Quantum Reflection of Massless Neutrinos from a Torsion-Induced Potential

NASA Astrophysics Data System (ADS)

Alimohammadi, M.; Shariati, A.

In the context of the Einstein-Cartan-Dirac model, where the torsion of the space-time couples to the axial currents of the fermions, we study the effects of this quantum-gravitational interaction on a massless neutrino beam crossing through a medium with a high number density of fermions at rest. We calculate the reflection amplitude and show that a specific fraction of the incident neutrinos reflects from this potential if the polarization of the medium is different from zero. We also discuss the order of magnitude of the fermionic number density in which this phenomenon is observable, in other theoretical contexts, for example, the strong gravity regime and the effective field theory approach.

Photon mass drag and the momentum of light in a medium

NASA Astrophysics Data System (ADS)

Partanen, Mikko; Häyrynen, Teppo; Oksanen, Jani; Tulkki, Jukka

2017-06-01

Conventional theories of electromagnetic waves in a medium assume that the energy propagating with the light pulse in the medium is entirely carried by the field. Thus, the possibility that the optical force field of the light pulse would drive forward an atomic mass density wave (MDW) and the related kinetic and elastic energies is neglected. In this work, we present foundations of a covariant theory of light propagation in a medium by considering a light wave simultaneously with the dynamics of the medium atoms driven by optoelastic forces between the induced dipoles and the electromagnetic field. We show that a light pulse having a total electromagnetic energy ℏ ω propagating in a nondispersive medium transfers a mass equal to δ m =(n2-1 ) ℏ ω /c2 , where n is the refractive index. MDW, which carries this mass, consists of atoms, which are more densely spaced inside the light pulse as a result of the field-dipole interaction. We also prove that the transfer of mass with the light pulse, the photon mass drag effect, gives an essential contribution to the total momentum of the light pulse, which becomes equal to the Minkowski momentum pM=n ℏ ω /c . The field's share of the momentum is the Abraham momentum pA=ℏ ω /(n c ) , while the difference pM-pA is carried by MDW. Due to the coupling of the field and matter, only the total momentum of the light pulse and the transferred mass δ m can be directly measured. Thus, our theory gives an unambiguous physical meaning to the Abraham and Minkowski momenta. We also show that to solve the centenary Abraham-Minkowski controversy of the momentum of light in a nondispersive medium in a way that is consistent with Newton's first law, one must account for the mass transfer effect. We derive the photon mass drag effect using two independent but complementary covariant models. In the mass-polariton (MP) quasiparticle approach, we consider the light pulse as a coupled state between the photon and matter, isolated from the rest of the medium. The momentum and the transferred mass of MP follow unambiguously from the Lorentz invariance and the fundamental conservation laws of nature. To enable the calculation of the mass and momentum distribution of a light pulse, we have also generalized the electrodynamics of continuous media to account for the space- and time-dependent optoelastic dynamics of the medium driven by the field-dipole forces. In this optoelastic continuum dynamics (OCD) approach, we obtain with an appropriate space-time discretization a numerically accurate solution of the Newtonian continuum dynamics of the medium when the light pulse is propagating in it. The OCD simulations of a Gaussian light pulse propagating in a diamond crystal give the same momentum pM and the transferred mass δ m for the light pulse as the MP quasiparticle approach. Our simulations also show that, after photon transmission, some nonequilibrium of the mass distribution is left in the medium. Since the elastic forces are included in our simulations on equal footing with the optical forces, our simulations also depict how the mass and thermal equilibria are reestablished by elastic waves. In the relaxation process, a small amount of photon energy is dissipated into lattice heat. We finally discuss a possibility of an optical waveguide setup for experimental measurement of the transferred mass of the light pulse. Our main result that a light pulse is inevitably associated with an experimentally measurable mass is a fundamental change in our understanding of light propagation in a medium.

Light clusters in nuclear matter: Excluded volume versus quantum many-body approaches

NASA Astrophysics Data System (ADS)

Hempel, Matthias; Schaffner-Bielich, Jürgen; Typel, Stefan; Röpke, Gerd

2011-11-01

The formation of clusters in nuclear matter is investigated, which occurs, e.g., in low-energy heavy-ion collisions or core-collapse supernovae. In astrophysical applications, the excluded volume concept is commonly used for the description of light clusters. Here we compare a phenomenological excluded volume approach to two quantum many-body models, the quantum statistical model and the generalized relativistic mean-field model. All three models contain bound states of nuclei with mass number A≤4. It is explored to which extent the complex medium effects can be mimicked by the simpler excluded volume model, regarding the chemical composition and thermodynamic variables. Furthermore, the role of heavy nuclei and excited states is investigated by use of the excluded volume model. At temperatures of a few MeV the excluded volume model gives a poor description of the medium effects on the light clusters, but there the composition is actually dominated by heavy nuclei. At larger temperatures there is a rather good agreement, whereas some smaller differences and model dependencies remain.

Relativistic and Nuclear Medium Effects on the Coulomb Sum Rule.

PubMed

Cloët, Ian C; Bentz, Wolfgang; Thomas, Anthony W

2016-01-22

In light of the forthcoming high precision quasielastic electron scattering data from Jefferson Lab, it is timely for the various approaches to nuclear structure to make robust predictions for the associated response functions. With this in mind, we focus here on the longitudinal response function and the corresponding Coulomb sum rule for isospin-symmetric nuclear matter at various baryon densities. Using a quantum field-theoretic quark-level approach which preserves the symmetries of quantum chromodynamics, as well as exhibiting dynamical chiral symmetry breaking and quark confinement, we find a dramatic quenching of the Coulomb sum rule for momentum transfers |q|≳0.5  GeV. The main driver of this effect lies in changes to the proton Dirac form factor induced by the nuclear medium. Such a dramatic quenching of the Coulomb sum rule was not seen in a recent quantum Monte Carlo calculation for carbon, suggesting that the Jefferson Lab data may well shed new light on the explicit role of QCD in nuclei.

Evaluation of low- and medium-cost IMUs for airborne gravimetry with UAVs

NASA Astrophysics Data System (ADS)

Deurloo, R. A.; Bastos, M. L.; Geng, Y.; Yan, W.

2011-12-01

The use of Unmanned Aerial Vehicles (UAVs) has increased in a large number of fields and is proving to be a good alternative to aerial surveys with traditional (manned) aircraft. In the scope of the PITVANT (Projecto de Investigação e Tecnologia em Veículos Aéreos Não-Tripulados) project, a research project funded by the Portuguese Ministry of Defence that aims at the development and demonstration of tools and technologies for UAVs, the Astronomical Observatory of the Faculty of Sciences of the University of Porto is investigating the use of UAVs for regional airborne gravimetry. The goal is to implement a so-called strapdown gravimetry system, based on the integrated use of GNSS and a low- to medium-cost IMU (Inertial Measurement Unit) that can be setup on board the UAVs developed within PITVANT. Two basic approaches exist in strapdown GNSS/IMU gravimetry: - to compute gravity disturbances directly from the combination of GNSS derived accelerations with accelerations measured by the IMU (the accelerometry approach); - to estimate the gravity disturbances as part of an inertial navigation solution using an (extended) Kalman filter (the inertial navigation approach). Because of the limitation of low- to medium-cost inertial systems the latter approach was used here. This method has proven to be effective in previous studies with this type of GNSS/IMU systems. To define the final system architecture, the performance of several different inertial systems was recently tested during an airborne survey with a regular aircraft, i.e. a CASA C212 from the Portuguese Air Force (PAF). Among the systems on board were a medium-cost Litton LN-200 and a low-cost Crossbow AHRS440, combined with a single GNSS receiver. Different Kalman filter configurations and GNSS processing options were investigated for each of the systems. The main goal was to assess the limits of the integrated GNSS/IMU systems to sense the gravity field (scalar gravimetry) and to evaluate their use and effectiveness in UAVs. The results of this analysis are presented here.

Optimization of medium components and physicochemical parameters to simultaneously enhance microbial growth and production of lypolitic enzymes by Stenotrophomonas sp.

PubMed

Mazzucotelli, Cintia Anabela; Agüero, María Victoria; Del Rosario Moreira, María; Ansorena, María Roberta

2016-05-01

The optimization of lipase and esterase production (LP and EP) and bacterial growth (BG) of a Stenotrophomonas sp. strain was developed. For this purpose, the effect of five different medium components and three physicochemical parameters were evaluated using a Plackett-Burman statistical design. Among eight variables, stirring speed, pH, and peptone concentration were found to be the most effective factors on the three responses under evaluation. An optimization study applying Box-Behnken response surface methodology was used to study the interactive effects of the three selected variables on LP/EP and microorganism growth. Predicted models were found to be significant with high regression coefficients (90%-99%). By using the desirability function approach, the optimum condition applying simultaneous optimization of the three responses under study resulted to be: stirring speed of 100 rpm, pH of 7.5, and a peptone concentration of 10 g/L, with a desirability value of 0.977. Under these optimal conditions, it is possible to achieve in the optimized medium a 15-fold increase in esterase productivity, a 117-fold increase in lipase production, and a 9-log CFU/mL increase in BG, compared with the basal medium without agitation. © 2015 International Union of Biochemistry and Molecular Biology, Inc.

A method for calculating proton-nucleus elastic cross-sections

NASA Technical Reports Server (NTRS)

Tripathi, R. K.; Wilson, J. W.; Cucinotta, F. A.

2002-01-01

Recently [Nucl. Instr. and Meth. B 145 (1998) 277; Extraction of in-medium nucleon-nucleon amplitude from experiment, NASA-TP, 1998], we developed a method of extracting nucleon-nucleon (N-N) cross-sections in the medium directly from experiment. The in-medium N-N cross-sections form the basic ingredients of several heavy-ion scattering approaches including the coupled-channel approach developed at the NASA Langley Research Center. We investigated [Proton-nucleus total cross-sections in coupled-channel approach, NASA/TP, 2000; Nucl. Instr. and Meth. B 173-174 (2001) 391] the ratio of real to imaginary part of the two body scattering amplitude in the medium. These ratios are used in combination with the in-medium N-N cross-sections to calculate proton-nucleus elastic cross-sections. The agreement is excellent with the available experimental data. These cross-sections are needed for the radiation risk assessment of space missions. c2002 Elsevier Science B.V. All rights reserved.

Multiple-layered effective medium approximation approach to modeling environmental effects on alumina passivated highly porous silicon nanostructured thin films measured by in-situ Mueller matrix ellipsometry

NASA Astrophysics Data System (ADS)

Mock, Alyssa; Carlson, Timothy; VanDerslice, Jeremy; Mohrmann, Joel; Woollam, John A.; Schubert, Eva; Schubert, Mathias

2017-11-01

Optical changes in alumina passivated highly porous silicon slanted columnar thin films during controlled exposure to toluene vapor are reported. Electron-beam evaporation glancing angle deposition and subsequent atomic layer deposition are utilized to deposit alumina passivated nanostructured porous silicon thin films. In-situ Mueller matrix generalized spectroscopic ellipsometry in an environmental cell is then used to determine changes in optical properties of the nanostructured thin films by inspection of individual Mueller matrix elements, each of which exhibit sensitivity to adsorption. The use of a multiple-layered effective medium approximation model allows for accurate description of the inhomogeneous nature of toluene adsorption onto alumina passivated highly porous silicon slanted columnar thin films.

Applicability of the Effective-Medium Approximation to Heterogeneous Aerosol Particles.

NASA Technical Reports Server (NTRS)

Mishchenko, Michael I.; Dlugach, Janna M.; Liu, Li

2016-01-01

The effective-medium approximation (EMA) is based on the assumption that a heterogeneous particle can have a homogeneous counterpart possessing similar scattering and absorption properties. We analyze the numerical accuracy of the EMA by comparing superposition T-matrix computations for spherical aerosol particles filled with numerous randomly distributed small inclusions and Lorenz-Mie computations based on the Maxwell-Garnett mixing rule. We verify numerically that the EMA can indeed be realized for inclusion size parameters smaller than a threshold value. The threshold size parameter depends on the refractive-index contrast between the host and inclusion materials and quite often does not exceed several tenths, especially in calculations of the scattering matrix and the absorption cross section. As the inclusion size parameter approaches the threshold value, the scattering-matrix errors of the EMA start to grow with increasing the host size parameter and or the number of inclusions. We confirm, in particular, the existence of the effective-medium regime in the important case of dust aerosols with hematite or air-bubble inclusions, but then the large refractive-index contrast necessitates inclusion size parameters of the order of a few tenths. Irrespective of the highly restricted conditions of applicability of the EMA, our results provide further evidence that the effective-medium regime must be a direct corollary of the macroscopic Maxwell equations under specific assumptions.

Technological effect of vibroprocessing by flows of organic granular media

NASA Astrophysics Data System (ADS)

Lebedev, V. A.; Shishkina, A. P.; Davydova, I. V.; Morozova, A. V.

2018-03-01

The analysis of approaches to modeling of vibrational processing by granulated media is carried out. The vibroprocessing model which provides effective finishing of the surfaces of the parts due to the stone fruit organic media granules is developed. The model is based on the granule flow energy impact on the surface being treated. As the main characteristic of the organic media processing, a specific volumetric metal scrap is used, the physical meaning of which is the increase rate in the thickness of the material removed from the surface at a given velocity and pressure of the medium. It is shown that the metal scrap depends on the medium flow velocity, the height of the loading column of the granular medium, and the conditions for the formation of a medium stationary circulation motion. Based on the analysis of the results of experimental studies of the influence of amplitude-frequency characteristics on the removal of metal in the process of vibroprocessing with abrasive granules, the dependence of the specific volume metal removal is proposed for organic media processing, taking into account the threshold amplitude and frequency of oscillations of the working chamber, at which the effect of surface treatment is observed. The established set of relationships describing the effective conditions for vibroprocessing with stone organic media was obtained using experimental data, which allows us to assume that the model obtained is valid.

The Comparative Instructional Effectiveness of Print-Based and Video-Based Instructional Materials for Teaching Practical Skills at a Distance

ERIC Educational Resources Information Center

Donkor, Francis

2010-01-01

Print-based instructional materials have been more popular than any other medium for teaching practical skills during the delivery of technical and vocational education and training via distance learning. However, the approach has its shortcomings and in recent times alternatives have been sought. The comparative instructional effectiveness of one…

STD 105: Process Groups as an Instructional Medium for Re-entry Women at Paul D. Camp Community College.

ERIC Educational Resources Information Center

Creamer, Elizabeth; Duggin, Molly; Kidd, Ronald

1999-01-01

An effective team-based, group-oriented personal development from a woman's perspective course explores the effects of several issues on the re-entry woman: the role that society and culture play in influencing women's vocational choices; women's roles; the economic necessity of work; stress; and relationships. A team-based approach provides a…

A MULTIFACETED, MEDIUM-THROUGHPUT APPROACH FOR DETECTING AND CHARACTERIZING DEVELOPMENTAL NEUROTOXICITY USING ZEBRAFISH.

EPA Science Inventory

To address the EPA's need to prioritize hundreds to thousands of chemicals for testing, we are developing a rapid, cost-effective in vivo screen for developmental neurotoxicity using zebrafish (Danio rerio), a small freshwater fish with external fertilization. Zebrafish embryos d...

A non-linear steady state characteristic performance curve for medium temperature solar energy collectors

NASA Astrophysics Data System (ADS)

Eames, P. C.; Norton, B.

A numerical simulation model was employed to investigate the effects of ambient temperature and insolation on the efficiency of compound parabolic concentrating solar energy collectors. The limitations of presently-used collector performance characterization curves were investigated and a new approach proposed.

Heat and Mass Transfer in an L Shaped Porous Medium

NASA Astrophysics Data System (ADS)

Salman Ahmed, N. J.; Azeem; Yunus Khan, T. M.

2017-08-01

This article is an extension to the heat transfer in L-shaped porous medium by including the mass diffusion. The heat and mass transfer in the porous domain is represented by three coupled partial differential equations representing the fluid movement, energy transport and mass transport. The equations are converted into algebraic form of equations by the application of finite element method that can be conveniently solved by matrix method. An iterative approach is adopted to solve the coupled equations by setting suitable convergence criterion. The results are discussed in terms of heat transfer characteristics influenced by physical parameters such as buoyancy ratio, Lewis number, Rayleigh number etc. It is found that these physical parameters have significant effect on heat and mass transfer behavior of L-shaped porous medium.

Experimental study of porous media flow using hydro-gel beads and LED based PIV

NASA Astrophysics Data System (ADS)

Harshani, H. M. D.; Galindo-Torres, S. A.; Scheuermann, A.; Muhlhaus, H. B.

2017-01-01

A novel experimental approach for measuring porous flow characteristics using spherical hydro-gel beads and particle image velocimetry (PIV) technique is presented. A transparent porous medium consisting of hydro-gel beads that are made of a super-absorbent polymer, allows using water as the fluid phase while simultaneously having the same refractive index. As a result, a more adaptable and cost effective refractive index matched (RIM) medium is created. The transparent nature of the porous medium allows optical systems to visualize the flow field by using poly-amide seeding particles (PSP). Low risk light emitting diode (LED) based light was used to illuminate the plane in order to track the seeding particles’ path for the characterization of the flow inside the porous medium. The system was calibrated using a manually measured flow by a flow meter. Velocity profiles were obtained and analysed qualitatively and quantitatively in order to characterise the flow. Results show that this adaptable, low risk experimental set-up can be used for flow measurements in porous medium under low Reynolds numbers. The limitations of using hydro-gel beads are also discussed.

A Hybrid Approach for Efficient Modeling of Medium-Frequency Propagation in Coal Mines

PubMed Central

Brocker, Donovan E.; Sieber, Peter E.; Waynert, Joseph A.; Li, Jingcheng; Werner, Pingjuan L.; Werner, Douglas H.

2015-01-01

An efficient procedure for modeling medium frequency (MF) communications in coal mines is introduced. In particular, a hybrid approach is formulated and demonstrated utilizing ideal transmission line equations to model MF propagation in combination with full-wave sections used for accurate simulation of local antenna-line coupling and other near-field effects. This work confirms that the hybrid method accurately models signal propagation from a source to a load for various system geometries and material compositions, while significantly reducing computation time. With such dramatic improvement to solution times, it becomes feasible to perform large-scale optimizations with the primary motivation of improving communications in coal mines both for daily operations and emergency response. Furthermore, it is demonstrated that the hybrid approach is suitable for modeling and optimizing large communication networks in coal mines that may otherwise be intractable to simulate using traditional full-wave techniques such as moment methods or finite-element analysis. PMID:26478686

Physically-Based Rendering of Particle-Based Fluids with Light Transport Effects

NASA Astrophysics Data System (ADS)

Beddiaf, Ali; Babahenini, Mohamed Chaouki

2018-03-01

Recent interactive rendering approaches aim to efficiently produce images. However, time constraints deeply affect their output accuracy and realism (many light phenomena are poorly or not supported at all). To remedy this issue, in this paper, we propose a physically-based fluid rendering approach. First, while state-of-the-art methods focus on isosurface rendering with only two refractions, our proposal (1) considers the fluid as a heterogeneous participating medium with refractive boundaries, and (2) supports both multiple refractions and scattering. Second, the proposed solution is fully particle-based in the sense that no particles transformation into a grid is required. This interesting feature makes it able to handle many particle types (water, bubble, foam, and sand). On top of that, a medium with different fluids (color, phase function, etc.) can also be rendered.

Efficient micropropagation and chlorocholine chloride induced stevioside production of Stevia rebaudiana Bertoni.

PubMed

Dey, Avishek; Kundu, Sayanti; Bandyopadhyay, Abhijit; Bhattacharjee, Aloke

2013-01-01

A promising method of micropropagation of Stevia rebaudiana Bertoni has been developed with an aim to increase the biomass, survivability of the plantlets and stevioside production, using chlorocholine chloride (CCC). Microshoots transferred to the MS medium containing different combinations CCC and IBA were found to be most effective in terms of growth pattern, hardening ability of the plantlets and stevioside content, compared to MS medium containing either IBA or CCC. Among other combinations tested, MS medium supplemented with 3 mg/l CCC and 3 mg/l IBA was found most effective in inducing significant changes like reduced shoot length, increased number of roots, higher leaf size, increased biomass and chlorophyll retaining capacity, higher survival percentage and most importantly the elevated stevioside content. Collectively, the major observations of this research indicate that application of CCC in micropropagation of S. rebaudiana Bertoni is a promising approach and has commercial prospects. Copyright © 2012 Académie des sciences. Published by Elsevier SAS. All rights reserved.

Story Maps as an Effective Social Medium for Data Synthesis, Communication, and Dissemination

NASA Astrophysics Data System (ADS)

Wright, D. J.; Verrill, A.; Artz, M.; Deming, R.

2014-12-01

The story map is a new medium for sharing not only data, but also photos, videos, sounds, and maps, as a way to tell a specific and compelling story by way of that content. It is emerging as a popular and effective social media too. The user may employ some fairly sophisticated cartographic functionality without advanced training in cartography or GIS. Story maps are essentially web map applications built from web maps, which in turn are built from web-accessible data (including OGC WMS, WFS). This paper will emphasize the approaches and technologies of web-based GIS to tell "stories" about important connections among scientists, resource managers, and policy makers focused on oceans and coasts within the US; and how combining the new medium of "intelligent Web maps" with text, multimedia content, and intuitive user experiences has a great potential to synthesize the data, and it primary interpretative message in order to inform, educate, and inspire about a wide variety of ocean science and policy issues.

Electromagnetic stress at the boundary: Photon pressure or tension?

PubMed

Wang, Shubo; Ng, Jack; Xiao, Meng; Chan, Che Ting

2016-03-01

It is well known that incident photons carrying momentum ℏk exert a positive photon pressure. But if light is impinging from a negative refractive medium in which ℏk is directed toward the source of radiation, should light exert a photon "tension" instead of a photon pressure? Using an ab initio method that takes the underlying microstructure of a material into account, we find that when an electromagnetic wave propagates from one material into another, the electromagnetic stress at the boundary is, in fact, indeterminate if only the macroscopic parameters are specified. Light can either pull or push the boundary, depending not only on the macroscopic parameters but also on the microscopic lattice structure of the polarizable units that constitute the medium. Within the context of an effective-medium approach, the lattice effect is attributed to electrostriction and magnetostriction, which can be accounted for by the Helmholtz stress tensor if we use the macroscopic fields to calculate the boundary optical stress.

Electromagnetic stress at the boundary: Photon pressure or tension?

PubMed Central

Wang, Shubo; Ng, Jack; Xiao, Meng; Chan, Che Ting

2016-01-01

It is well known that incident photons carrying momentum ℏk exert a positive photon pressure. But if light is impinging from a negative refractive medium in which ℏk is directed toward the source of radiation, should light exert a photon “tension” instead of a photon pressure? Using an ab initio method that takes the underlying microstructure of a material into account, we find that when an electromagnetic wave propagates from one material into another, the electromagnetic stress at the boundary is, in fact, indeterminate if only the macroscopic parameters are specified. Light can either pull or push the boundary, depending not only on the macroscopic parameters but also on the microscopic lattice structure of the polarizable units that constitute the medium. Within the context of an effective-medium approach, the lattice effect is attributed to electrostriction and magnetostriction, which can be accounted for by the Helmholtz stress tensor if we use the macroscopic fields to calculate the boundary optical stress. PMID:27034987

The Cotton-Mouton effect of liquid water. Part I: The dielectric continuum model

NASA Astrophysics Data System (ADS)

Ruud, Kenneth; Helgaker, Trygve; Rizzo, Antonio; Coriani, Sonia; Mikkelsen, Kurt V.

1997-07-01

We present a gauge-origin independent method for calculating the electric-field dependence of the molecular magnetizability—that is, the hypermagnetizability, related to the Cotton-Mouton Effect (CME)—of solvated molecules. In our approach, the solvated molecule is placed in a spherical cavity surrounded by a linear, homogeneous, and polarizable dielectric medium. We apply the model to investigate the dielectric-medium effects on the CME of liquid water. The effects of electron correlation, molecular geometry, and the surrounding dielectric continuum on the hypermagnetizability and the CME are investigated. The change induced in the hypermagnetizability anisotropy by the dielectric medium is the dominating effect, being almost twice as large as the correlation contribution. The combined effect of electron correlation and the dielectric continuum leads to a doubling of the hypermagnetizability anisotropy when going from the SCF gas phase value (Δη=17.89 a.u.) to the value obtained for the MCSCF wave function in the dielectric medium (Δη=39.74 a.u.). The effects of change in geometry are shown to be small. Our result for the static Cotton-Mouton constant averaged in the temperature range 283.15 K to 293.15 K, mC=15.2×10-20 G-2 cm3 mol-1, differs from experiment still by the sign and by a factor of almost 8. The major reason for this discrepancy is the neglect of short-range interactions such as hydrogen bonding and van der Waals interactions not accounted for by the continuum model.

A multi-frequency iterative imaging method for discontinuous inverse medium problem

NASA Astrophysics Data System (ADS)

Zhang, Lei; Feng, Lixin

2018-06-01

The inverse medium problem with discontinuous refractive index is a kind of challenging inverse problem. We employ the primal dual theory and fast solution of integral equations, and propose a new iterative imaging method. The selection criteria of regularization parameter is given by the method of generalized cross-validation. Based on multi-frequency measurements of the scattered field, a recursive linearization algorithm has been presented with respect to the frequency from low to high. We also discuss the initial guess selection strategy by semi-analytical approaches. Numerical experiments are presented to show the effectiveness of the proposed method.

Effect of mineral nutrients on cell growth and self-flocculation of Tolypothrix tenuis for the production of a biofertilizer.

PubMed

Silva, P G; Silva, H J

2007-02-01

The influence of mineral nutrients on the growth and self-flocculation of Tolypothrix tenuis was studied. The identification of possible limiting nutrients in the culture medium was performed by the biomass elemental composition approach. A factorial experimental design was used in order to estimate the contribution of macronutrients and micronutrients, as well as their interactions. Iron was identified to be limiting in the culture medium. The micronutrients influenced mainly cellular growth without effects on self-flocculation. Conversely, the self-flocculation capacity of the biomass increased at higher concentrations of macronutrients. The optimization of mineral nutrition of T. tenuis allowed a 73% increase in the final biomass level and 3.5 times higher flocculation rates.

Effects of a blended learning approach on student outcomes in a graduate-level public health course

PubMed Central

2014-01-01

Background Blended learning approaches, in which in-person and online course components are combined in a single course, are rapidly increasing in health sciences education. Evidence for the relative effectiveness of blended learning versus more traditional course approaches is mixed. Method The impact of a blended learning approach on student learning in a graduate-level public health course was examined using a quasi-experimental, non-equivalent control group design. Exam scores and course point total data from a baseline, “traditional” approach semester (n = 28) was compared to that from a semester utilizing a blended learning approach (n = 38). In addition, student evaluations of the blended learning approach were evaluated. Results There was a statistically significant increase in student performance under the blended learning approach (final course point total d = 0.57; a medium effect size), even after accounting for previous academic performance. Moreover, student evaluations of the blended approach were very positive and the majority of students (83%) preferred the blended learning approach. Conclusions Blended learning approaches may be an effective means of optimizing student learning and improving student performance in health sciences courses. PMID:24612923

Creating Visuals for TV; A Guide for Educators.

ERIC Educational Resources Information Center

Spear, James

There are countless ways educators can improve the quality of their educational television offerings. The Guide, planned especially for the television teacher or audiovisual director, particularly those approaching the television medium for the first time, is designed to acquaint the reader with production techniques for effective visuals to…

Freight distribution problems in congested urban areas : fast and effective solution procedures to time-dependent vehicle routing problems

DOT National Transportation Integrated Search

2011-01-01

Congestion is a common phenomenon in all medium to large cities of the world. Reliability of freight movement in urban areas is an important : issue to manufacturing or service companies whose operation is based in just-in-time approaches. These comp...

A Scenario Approach to Assessment of New Communications Media.

ERIC Educational Resources Information Center

Spangler, Kathleen; And Others

In a study supported by the Charles F. Kettering Foundation, a research team developed a methodology for illustrating the effective and ineffective uses of audio, video, and computer teleconferencing by developing scenarios for eacb medium. The group first invented a general situation--a conference involving participants with global, regional, and…

An Evaluation of 25 Selected ToxCast Chemicals in Medium-Throughput Assays to Detect Genotoxicity

EPA Science Inventory

ABSTRACTToxCast is a multi-year effort to develop a cost-effective approach for the US EPA to prioritize chemicals for toxicity testing. Initial evaluation of more than 500 high-throughput (HT) microwell-based assays without metabolic activation showed that most lacked high speci...

Neutrino Processes in Neutron Stars

NASA Astrophysics Data System (ADS)

Kolomeitsev, E. E.; Voskresensky, D. N.

2010-10-01

The aim of these lectures is to introduce basic processes responsible for cooling of neutron stars and to show how to calculate the neutrino production rate in dense strongly interacting nuclear medium. The formalism is presented that treats on equal footing one-nucleon and multiple-nucleon processes and reactions with virtual bosonic modes and condensates. We demonstrate that neutrino emission from dense hadronic component in neutron stars is subject of strong modifications due to collective effects in the nuclear matter. With the most important in-medium processes incorporated in the cooling code an overall agreement with available soft X ray data can be easily achieved. With these findings the so-called “standard” and “non-standard” cooling scenarios are replaced by one general “nuclear medium cooling scenario” which relates slow and rapid neutron star coolings to the star masses (interior densities). The lectures are split in four parts. Part I: After short introduction to the neutron star cooling problem we show how to calculate neutrino reaction rates of the most efficient one-nucleon and two-nucleon processes. No medium effects are taken into account in this instance. The effects of a possible nucleon pairing are discussed. We demonstrate that the data on neutron star cooling cannot be described without inclusion of medium effects. It motivates an assumption that masses of the neutron stars are different and that neutrino reaction rates should be strongly density dependent. Part II: We introduce the Green’s function diagram technique for systems in and out of equilibrium and the optical theorem formalism. The latter allows to perform calculations of production rates with full Green’s functions including all off-mass-shell effects. We demonstrate how this formalism works within the quasiparticle approximation. Part III: The basic concepts of the nuclear Fermi liquid approach are introduced. We show how strong interaction effects can be included within the Green’s function formalism. Softening of the pion mode with an baryon density increase is explicitly incorporated. We show examples of inconsistencies in calculations without inclusion of medium effects. Then we demonstrate calculations of different reaction rates in non-superfluid nuclear matter with taking into account medium effects. Many new reaction channels are open up in the medium and should be analyzed. Part IV: We discuss the neutrino production reactions in superfluid nuclear systems. The reaction rates of processes associated with the pair breaking and formation are calculated. Special attention is focused on the gauge invariance and the exact fulfillment of the Ward identities for the vector current. Finally we present comparison of calculations of neutron star cooling performed within nuclear medium cooling scenario with the available data.

In-Medium Parton Branching Beyond Eikonal Approximation

NASA Astrophysics Data System (ADS)

Apolinário, Liliana

2017-03-01

The description of the in-medium modifications of partonic showers has been at the forefront of current theoretical and experimental efforts in heavy-ion collisions. It provides a unique laboratory to extend our knowledge frontier of the theory of the strong interactions, and to assess the properties of the hot and dense medium (QGP) that is produced in ultra-relativistic heavy-ion collisions at RHIC and the LHC. The theory of jet quenching, a commonly used alias for the modifications of the parton branching resulting from the interactions with the QGP, has been significantly developed over the last years. Within a weak coupling approach, several elementary processes that build up the parton shower evolution, such as single gluon emissions, interference effects between successive emissions and corrections to radiative energy loss of massive quarks, have been addressed both at eikonal accuracy and beyond by taking into account the Brownian motion that high-energy particles experience when traversing a hot and dense medium. In this work, by using the setup of single gluon emission from a color correlated quark-antiquark pair in a singlet state (qbar{q} antenna), we calculate the in-medium gluon radiation spectrum beyond the eikonal approximation. The results show that we are able to factorize broadening effects from the modifications of the radiation process itself. This constitutes the final proof that a probabilistic picture of the parton shower evolution holds even in the presence of a QGP.

Intrinsic Multi-Scale Dynamic Behaviors of Complex Financial Systems.

PubMed

Ouyang, Fang-Yan; Zheng, Bo; Jiang, Xiong-Fei

2015-01-01

The empirical mode decomposition is applied to analyze the intrinsic multi-scale dynamic behaviors of complex financial systems. In this approach, the time series of the price returns of each stock is decomposed into a small number of intrinsic mode functions, which represent the price motion from high frequency to low frequency. These intrinsic mode functions are then grouped into three modes, i.e., the fast mode, medium mode and slow mode. The probability distribution of returns and auto-correlation of volatilities for the fast and medium modes exhibit similar behaviors as those of the full time series, i.e., these characteristics are rather robust in multi time scale. However, the cross-correlation between individual stocks and the return-volatility correlation are time scale dependent. The structure of business sectors is mainly governed by the fast mode when returns are sampled at a couple of days, while by the medium mode when returns are sampled at dozens of days. More importantly, the leverage and anti-leverage effects are dominated by the medium mode.

Using straw hydrolysate to cultivate Chlorella pyrenoidosa for high-value biomass production and the nitrogen regulation for biomass composition.

PubMed

Zhang, Tian-Yuan; Wang, Xiao-Xiong; Wu, Yin-Hu; Wang, Jing-Han; Deantes-Espinosa, Victor M; Zhuang, Lin-Lan; Hu, Hong-Ying; Wu, Guang-Xue

2017-11-01

Heterotrophic cultivation of Chlorella pyrenoidosa based on straw substrate was proposed as a promising approach in this research. The straw pre-treated by ammonium sulfite method was enzymatically hydrolyzed for medium preparation. The highest intrinsic growth rate of C. pyrenoidosa reached to 0.097h -1 in hydrolysate medium, which was quicker than that in glucose medium. Rising nitrogen concentration could significantly increase protein content and decrease lipid content in biomass, meanwhile fatty acids composition kept stable. The highest protein and lipid content in microalgal biomass reached to 62% and 32% under nitrogen excessive and deficient conditions, respectively. Over 40% of amino acids and fatty acids in biomass belonged to essential amino acids (EAA) and essential fatty acids (EFA), which were qualified for high-value uses. This research revealed the rapid biomass accumulation property of C. pyrenoidosa in straw hydrolysate medium and the effectiveness of nitrogen regulation to biomass composition at heterotrophic condition. Copyright © 2017. Published by Elsevier Ltd.

Lattice NRQCD study on in-medium bottomonium spectra using a novel Bayesian reconstruction approach

NASA Astrophysics Data System (ADS)

Kim, Seyong; Petreczky, Peter; Rothkopf, Alexander

2016-01-01

We present recent results on the in-medium modification of S- and P-wave bottomonium states around the deconfinement transition. Our study uses lattice QCD with Nf = 2 + 1 light quark flavors to describe the non-perturbative thermal QCD medium between 140MeV < T < 249MeV and deploys lattice regularized non-relativistic QCD (NRQCD) effective field theory to capture the physics of heavy quark bound states immersed therein. The spectral functions of the 3S1 (ϒ) and 3P1 (χb1) bottomonium states are extracted from Euclidean time Monte Carlo simulations using a novel Bayesian prescription, which provides higher accuracy than the Maximum Entropy Method. Based on a systematic comparison of interacting and free spectral functions we conclude that the ground states of both the S-wave (ϒ) and P-wave (χb1) channel survive up to T = 249MeV. Stringent upper limits on the size of the in-medium modification of bottomonium masses and widths are provided.

Buckling, stiffening, and negative dissipation in the dynamics of a biopolymer in an active medium

PubMed Central

Kikuchi, Norio; Ehrlicher, Allen; Koch, Daniel; Käs, Josef A.; Ramaswamy, Sriram; Rao, Madan

2009-01-01

We present a generic theory for the dynamics of a stiff filament under tension, in an active medium with orientational correlations, such as a microtubule in contractile actin. In sharp contrast to the case of a passive medium, we find the filament can stiffen, and possibly oscillate or buckle, depending on both the contractile or tensile nature of the activity and the filament-medium anchoring interaction. We also demonstrate a strong violation of the fluctuation–dissipation (FD) relation in the effective dynamics of the filament, including a negative FD ratio. Our approach is also of relevance to the dynamics of axons, and our model equations bear a remarkable formal similarity to those in recent work [Martin P, Hudspeth AJ, Juelicher F (2001) Proc Natl Acad Sci USA 98:14380–14385] on auditory hair cells. Detailed tests of our predictions can be made by using a single filament in actomyosin extracts or bacterial suspensions. PMID:19901332

Finite-size effects on the radiative energy loss of a fast parton in hot and dense strongly interacting matter

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

Caron-Huot, Simon; Gale, Charles

2010-12-15

We consider finite-size effects on the radiative energy loss of a fast parton moving in a finite-temperature, strongly interacting medium, using the light-cone path integral formalism put forward by B. G. Zakharov [JETP Lett. 63, 952 (1996); 65, 615 (1997)]. We present a convenient reformulation of the problem that makes possible its exact numerical analysis. This is done by introducing the concept of a radiation rate in the presence of finite-size effects. This effectively extends the finite-temperature approach of Arnold, Moore, and Yaffe [J. High Energy Phys. 11 (2001) 057; 12 (2001) 009; 06 (2001) 030] (AMY) to include interferencemore » between vacuum and medium radiation. We compare results with those obtained in the regime considered by AMY, with those obtained at leading order in an opacity expansion, and with those obtained deep in the Landau-Pomeranchuk-Migdal regime.« less

Efficacy of cognitive-behavioral therapy for childhood anxiety and depression.

PubMed

Crowe, Katherine; McKay, Dean

2017-06-01

A review of meta-analyses of cognitive-behavioral therapy (CBT) for childhood anxiety and depression was conducted. A total of 36 meta-analyses were identified that met inclusion criteria for this review. In most cases, medium-to-large effect sizes for treatment reduction were observed when CBT was compared to non-active control conditions. Small-to-medium effects were observed when CBT was compared to active control treatments. The available meta-analyses generally did not examine, or data were not sufficient to evaluate, potential moderators of outcome, differential effects for parental involvement, or changes in quality of life or functional outcomes associated with treatment. Accordingly, while CBT should be broadly considered an effective treatment approach for childhood anxiety and depression, additional research is warranted in order to establish guidelines for service delivery for complicating factors in client presentation. Copyright © 2017 Elsevier Ltd. All rights reserved.

How good is the turbid medium-based approach for accounting for light partitioning in contrasted grass--legume intercropping systems?

PubMed

Barillot, Romain; Louarn, Gaëtan; Escobar-Gutiérrez, Abraham J; Huynh, Pierre; Combes, Didier

2011-10-01

Most studies dealing with light partitioning in intercropping systems have used statistical models based on the turbid medium approach, thus assuming homogeneous canopies. However, these models could not be directly validated although spatial heterogeneities could arise in such canopies. The aim of the present study was to assess the ability of the turbid medium approach to accurately estimate light partitioning within grass-legume mixed canopies. Three contrasted mixtures of wheat-pea, tall fescue-alfalfa and tall fescue-clover were sown according to various patterns and densities. Three-dimensional plant mock-ups were derived from magnetic digitizations carried out at different stages of development. The benchmarks for light interception efficiency (LIE) estimates were provided by the combination of a light projective model and plant mock-ups, which also provided the inputs of a turbid medium model (SIRASCA), i.e. leaf area index and inclination. SIRASCA was set to gradually account for vertical heterogeneity of the foliage, i.e. the canopy was described as one, two or ten horizontal layers of leaves. Mixtures exhibited various and heterogeneous profiles of foliar distribution, leaf inclination and component species height. Nevertheless, most of the LIE was satisfactorily predicted by SIRASCA. Biased estimations were, however, observed for (1) grass species and (2) tall fescue-alfalfa mixtures grown at high density. Most of the discrepancies were due to vertical heterogeneities and were corrected by increasing the vertical description of canopies although, in practice, this would require time-consuming measurements. The turbid medium analogy could be successfully used in a wide range of canopies. However, a more detailed description of the canopy is required for mixtures exhibiting vertical stratifications and inter-/intra-species foliage overlapping. Architectural models remain a relevant tool for studying light partitioning in intercropping systems that exhibit strong vertical heterogeneities. Moreover, these models offer the possibility to integrate the effects of microclimate variations on plant growth.

On gel electrophoresis of dielectric charged particles with hydrophobic surface: A combined theoretical and numerical study.

PubMed

Majee, Partha Sarathi; Bhattacharyya, Somnath; Gopmandal, Partha Pratim; Ohshima, Hiroyuki

2018-03-01

A theoretical study on the gel electrophoresis of a charged particle incorporating the effects of dielectric polarization and surface hydrophobicity at the particle-liquid interface is made. A simplified model based on the weak applied field and low charge density assumption is also presented and compared with the full numerical model for a nonpolarizable particle to elucidate the nonlinear effects such as double layer polarization and relaxation as well as surface conduction. The main motivation of this study is to analyze the electrophoresis of the surface functionalized nanoparticle with tunable hydrophobicity or charged fluid drop in gel medium by considering the electrokinetic effects and hydrodynamic interactions between the particle and the gel medium. An effective medium approach, in which the transport in the electrolyte-saturated hydrogel medium is governed by the Brinkman equation, is adopted in the present analysis. The governing electrokinetic equations based on the conservation principles are solved numerically. The Navier-slip boundary condition along with the continuity condition of dielectric displacement are imposed on the surface of the hydrophobic polarizable particle. The impact of the slip length on the electrophoresis is profound for a thinner Debye layer, however, surface conduction effect also becomes significant for a hydrophobic particle. Impact of hydrophobicity and relaxation effects are higher for a larger particle. Dielectric polarization creates a reduction in its electrophoretic propulsion and has negligible impact at the thinner Debye length as well as lower gel screening length. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Evaluation of an Innovative Approach to Validation of ...

EPA Pesticide Factsheets

UV disinfection is an effective process for inactivating many microbial pathogens found in source waters with the potential as stand-alone treatment or in combination with other disinfectants. For surface and groundwater sourced drinking water applications, the U.S. Environmental Protection Agency (USEPA) provided guidance on the validation of UV reactors nearly a decade ago. The focus of the guidance was primarily for inactivation of Cryptosporidium and Giardia. Over the last ten years many lessons have been learned, validation practices have been modified, new science issues discovered, and changes in operation & monitoring of UV systems need to be addressed. Also, there remains no standard approach for validating UV reactors to meet a 4-log (99.99%) inactivation of viruses. USEPA in partnership with the Cadmus Group, Carollo Engineers, and other State & Industry collaborators, are evaluating new approaches for validating UV reactors to meet groundwater & surface water pathogen inactivation including viruses for low-pressure and medium-pressure UV systems. A particular challenge for medium-pressure UV is the monitoring of low-wavelength germicidal contributions for appropriate crediting of disinfection under varying reactor conditions of quartz sleeve fouling, lamp aging, and changes in UV absorbance of the water over time. In the current effort, bench and full-scale studies are being conducted on a low pressure (LP) UV reactor and a medium pressure (MP) UV re

Effect of primary and secondary parameters on analytical estimation of effective thermal conductivity of two phase materials using unit cell approach

NASA Astrophysics Data System (ADS)

S, Chidambara Raja; P, Karthikeyan; Kumaraswamidhas, L. A.; M, Ramu

2018-05-01

Most of the thermal design systems involve two phase materials and analysis of such systems requires detailed understanding of the thermal characteristics of the two phase material. This article aimed to develop geometry dependent unit cell approach model by considering the effects of all primary parameters (conductivity ratio and concentration) and secondary parameters (geometry, contact resistance, natural convection, Knudsen and radiation) for the estimation of effective thermal conductivity of two-phase materials. The analytical equations have been formulated based on isotherm approach for 2-D and 3-D spatially periodic medium. The developed models are validated with standard models and suited for all kind of operating conditions. The results have shown substantial improvement compared to the existing models and are in good agreement with the experimental data.

Effects of Composite Pions on the Chiral Condensate within the PNJL Model at Finite Temperature

NASA Astrophysics Data System (ADS)

Blaschke, D.; Dubinin, A.; Ebert, D.; Friesen, A. V.

2018-05-01

We investigate the effect of composite pions on the behaviour of the chiral condensate at finite temperature within the Polyakov-loop improved NJL model. To this end we treat quark-antiquark correlations in the pion channel (bound states and scattering continuum) within a Beth-Uhlenbeck approach that uses medium-dependent phase shifts. A striking medium effect is the Mott transition which occurs when the binding energy vanishes and the discrete pion bound state merges the continuum. This transition is triggered by the lowering of the continuum edge due to the chiral restoration transition. This in turn also entails a modification of the Polyakov-loop so that the SU(3) center symmetry gets broken at finite temperature and dynamical quarks (and gluons) appear in the system, taking over the role of the dominant degrees of freedom from the pions. At low temperatures our model reproduces the chiral perturbation theory result for the chiral condensate while at high temperatures the PNJL model result is recovered. The new aspect of the current work is a consistent treatment of the chiral restoration transition region within the Beth-Uhlenbeck approach on the basis of mesonic phase shifts for the treatment of the correlations.

Medium optimization by orthogonal array and response surface methodology for cholesterol oxidase production by Streptomyces lavendulae NCIM 2499.

PubMed

Chauhan, Awadesh K; Survase, Shrikant A; Kishenkumar, Jyoti; Annapure, Uday S

2009-06-01

This paper deals with the optimization of culture conditions for the production of cholesterol oxidase (COD) by Streptomyces lavendulae NCIM 2499 using the one-factor-at-a-time method, orthogonal array method and response surface methodology (RSM) approaches. The one-factor-at-a-time method was adopted to investigate the effects of medium components (i.e. carbon and nitrogen) and environmental factors (i.e. initial pH) on biomass growth and COD production. Subsequently, an L12 orthogonal matrix was used to evaluate the significance of glycerol, soyabean meal, malt extract, K2HPO4, MgSO4 and NaCl. The effects of media components were ranked according to their effects on the production of COD as malt extract > soyabean meal > K2HPO4 > NaCl > MgSO4 > glycerol. The subsequent optimization of the four most significant factors viz. malt extract, soyabean meal, K2HPO4 and NaCl, was carried out by employing a central composite rotatable design (CCRD) of RSM. There was a 2.48-fold increase in productivity of COD as compared to the unoptimized media by using these statistical approaches.

Domain wall network as QCD vacuum: confinement, chiral symmetry, hadronization

NASA Astrophysics Data System (ADS)

Nedelko, Sergei N.; Voronin, Vladimir V.

2017-03-01

An approach to QCD vacuum as a medium describable in terms of statistical ensemble of almost everywhere homogeneous Abelian (anti-)self-dual gluon fields is reviewed. These fields play the role of the confining medium for color charged fields as well as underline the mechanism of realization of chiral SUL(Nf) × SUR(Nf) and UA(1) symmetries. Hadronization formalism based on this ensemble leads to manifestly defined quantum effective meson action. Strong, electromagnetic and weak interactions of mesons are represented in the action in terms of nonlocal n-point interaction vertices given by the quark-gluon loops averaged over the background ensemble. Systematic results for the mass spectrum and decay constants of radially excited light, heavy-light mesons and heavy quarkonia are presented. Relationship of this approach to the results of functional renormalization group and Dyson-Schwinger equations, and the picture of harmonic confinement is briefly outlined.

Microenvironmental pH measurement during sodium naproxenate dissolution in acidic medium by UV/vis imaging.

PubMed

Østergaard, Jesper; Jensen, Henrik; Larsen, Susan W; Larsen, Claus; Lenke, Jim

2014-11-01

Variable dissolution from sodium salts of drugs containing a carboxylic acid group after passing the acidic environment of the stomach may affect oral bioavailability. The aim of the present proof of concept study was to investigate pH effects in relation to the dissolution of sodium naproxenate in 0.01M hydrochloric acid. For this purpose a UV/vis imaging-based approach capable of measuring microenvironmental pH in the vicinity of the solid drug compact as well as monitoring drug dissolution was developed. Using a pH indicating dye real-time spatially resolved measurement of pH was achieved. Sodium naproxenate, can significantly alter the local pH of the dissolution medium, is eventually neutralized and precipitates as the acidic species naproxen. The developed approach is considered useful for detailed studies of pH dependent dissolution phenomena in dissolution testing. Copyright © 2014 Elsevier B.V. All rights reserved.

A Lattice-Boltzmann model to simulate diffractive nonlinear ultrasound beam propagation in a dissipative fluid medium

NASA Astrophysics Data System (ADS)

Abdi, Mohamad; Hajihasani, Mojtaba; Gharibzadeh, Shahriar; Tavakkoli, Jahan

2012-12-01

Ultrasound waves have been widely used in diagnostic and therapeutic medical applications. Accurate and effective simulation of ultrasound beam propagation and its interaction with tissue has been proved to be important. The nonlinear nature of the ultrasound beam propagation, especially in the therapeutic regime, plays an important role in the mechanisms of interaction with tissue. There are three main approaches in current computational fluid dynamics (CFD) methods to model and simulate nonlinear ultrasound beams: macroscopic, mesoscopic and microscopic approaches. In this work, a mesoscopic CFD method based on the Lattice-Boltzmann model (LBM) was investigated. In the developed method, the Boltzmann equation is evolved to simulate the flow of a Newtonian fluid with the collision model instead of solving the Navier-Stokes, continuity and state equations which are used in conventional CFD methods. The LBM has some prominent advantages over conventional CFD methods, including: (1) its parallel computational nature; (2) taking microscopic boundaries into account; and (3) capability of simulating in porous and inhomogeneous media. In our proposed method, the propagating medium is discretized with a square grid in 2 dimensions with 9 velocity vectors for each node. Using the developed model, the nonlinear distortion and shock front development of a finiteamplitude diffractive ultrasonic beam in a dissipative fluid medium was computed and validated against the published data. The results confirm that the LBM is an accurate and effective approach to model and simulate nonlinearity in finite-amplitude ultrasound beams with Mach numbers of up to 0.01 which, among others, falls within the range of therapeutic ultrasound regime such as high intensity focused ultrasound (HIFU) beams. A comparison between the HIFU nonlinear beam simulations using the proposed model and pseudospectral methods in a 2D geometry is presented.

Exploring the cost-utility of stratified primary care management for low back pain compared with current best practice within risk-defined subgroups.

PubMed

Whitehurst, David G T; Bryan, Stirling; Lewis, Martyn; Hill, Jonathan; Hay, Elaine M

2012-11-01

Stratified management for low back pain according to patients' prognosis and matched care pathways has been shown to be an effective treatment approach in primary care. The aim of this within-trial study was to determine the economic implications of providing such an intervention, compared with non-stratified current best practice, within specific risk-defined subgroups (low-risk, medium-risk and high-risk). Within a cost-utility framework, the base-case analysis estimated the incremental healthcare cost per additional quality-adjusted life year (QALY), using the EQ-5D to generate QALYs, for each risk-defined subgroup. Uncertainty was explored with cost-utility planes and acceptability curves. Sensitivity analyses were performed to consider alternative costing methodologies, including the assessment of societal loss relating to work absence and the incorporation of generic (ie, non-back pain) healthcare utilisation. The stratified management approach was a cost-effective treatment strategy compared with current best practice within each risk-defined subgroup, exhibiting dominance (greater benefit and lower costs) for medium-risk patients and acceptable incremental cost to utility ratios for low-risk and high-risk patients. The likelihood that stratified care provides a cost-effective use of resources exceeds 90% at willingness-to-pay thresholds of £4000 (≈ 4500; $6500) per additional QALY for the medium-risk and high-risk groups. Patients receiving stratified care also reported fewer back pain-related days off work in all three subgroups. Compared with current best practice, stratified primary care management for low back pain provides a highly cost-effective use of resources across all risk-defined subgroups.

Survival in a Down Economy: A Budget Reduction Process for Superintendents

ERIC Educational Resources Information Center

Davis, E. E.; Coffland, Jack A.

2010-01-01

Dramatic reductions in the dollars available for public education require a new and systemic approach to balancing school district budgets. This manual provides numerous examples of successful budget reduction strategies based on a six-step process that has demonstrated its effectiveness in small, medium, and large school districts. Supported by…

English Through Drama: A Way of Teaching.

ERIC Educational Resources Information Center

Parry, Christopher

This book describes drama as a medium for effective English teaching. The author discusses his experiences while attempting to carry on a teaching approach, centered in dramatic activity, which had been developing in the Perse School, in Cambridge, England, for nearly fifty years. Having learned English at the same school and in the same…

A More Effective Way to Advertise the Distance Education Programmes: Mobile Marketing Approach

ERIC Educational Resources Information Center

Sabuncuoglu Aybar, Ayda; Gokaliler, Ebru

2011-01-01

Nowadays organizations strive to find the ways to communicate with their target audiences by using varied advertising mediums because of the developments on the information communication technologies and the globalization. In this context, like the other institutions, the distance education institutions has to execute communication activities by…

Student Response to Hypermedia in the Lecture Theatre: A Case Study.

ERIC Educational Resources Information Center

Conway, Damian

The Computer Science Department at Monash University (Victoria, Australia) recently began presenting lectures using projection of a hypertext system, HyperLecture, running on a notebook computer as the primary medium. This paper presents a statistical analysis of student reactions to this approach, focusing on the effects, as perceived by the…

Competitive Strategy and Influences on E-Learning in Entrepreneur-Led SMEs

ERIC Educational Resources Information Center

Roffe, Ian

2007-01-01

Purpose: To explore the influence of competitive strategy in entrepreneur-led SMEs and the effects on e-learning HRD. Design/methodology/approach: Performance consulting company reviews provide holistic information on nine case studies on small and medium sized enterprises drawn from the printing, agri-foods and media industries. Findings:…

Orthogonal array deciphering MRS medium requirements for isolated Lactobacillus rhamnosus ZY with cell properties characterization.

PubMed

Zhang, Yu; Ng, I-Son; Yao, Chuanyi; Lu, Yinghua

2014-09-01

Lactobacillus rhamnosus is a well-known lactic acid bacterium (LAB), but a new ZY strain was isolated for the first time from commercial probiotic powder recently. Although many studies have focused on developing cost-effective media for the production of LAB, the de Man, Rogosa and Sharpe (MRS) medium is still the most common medium for bioprocesses. The aim of the current study is to decipher the composition of MRS based on a statistical approach, which will allow a higher biomass of Lactobacillus to be obtained. In Taguchi's approach, an L27 orthogonal array was adopted to evaluate the significance of 10 ingredients in MRS, in which the effects of the components were ranked according to their effect on biomass at OD600 as dextrose > MnSO4·H2O > beef extract > CH3COONa > MgSO4 > yeast extract > proteose peptone > K2HPO4 > ammonium citrate > Tween 80. Although the individual trace elements of ammonium citrate, K2HPO4, CH3COONa and MgSO4 in MRS had an insignificant influence on the biomass after statistical analysis, the total elimination of trace elements would predominantly affect the cell growth of Lactobacillus. Further characterization of the cell properties through attenuated total reflectance of Fourier transform infrared (ATR-FTIR) spectroscopy and protein identification via SDS-PAGE coupled with tandem mass spectrometry implied that dextrose as major carbon source in MRS played the most crucial role for L. rhamnosus production. Copyright © 2014 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Inclusion-Based Effective Medium Models for the Permeability of a 3D Fractured Rock Mass

NASA Astrophysics Data System (ADS)

Ebigbo, A.; Lang, P. S.; Paluszny, A.; Zimmerman, R. W.

2015-12-01

Following the work of Saevik et al. (Transp. Porous Media, 2013; Geophys. Prosp., 2014), we investigate the ability of classical inclusion-based effective medium theories to predict the macroscopic permeability of a fractured rock mass. The fractures are assumed to be thin, oblate spheroids, and are treated as porous media in their own right, with permeability kf, and are embedded in a homogeneous matrix having permeability km. At very low fracture densities, the effective permeability is given exactly by a well-known expression that goes back at least as far as Fricke (Phys. Rev., 1924). For non-trivial fracture densities, an effective medium approximation must be employed. We have investigated several such approximations: Maxwell's method, the differential method, and the symmetric and asymmetric versions of the self-consistent approximation. The predictions of the various approximate models are tested against the results of explicit numerical simulations, averaged over numerous statistical realizations for each set of parameters. Each of the various effective medium approximations satisfies the Hashin-Shtrikman (H-S) bounds. Unfortunately, these bounds are much too far apart to provide quantitatively useful estimates of keff. For the case of zero matrix permeability, the well-known approximation of Snow, which is based on network considerations rather than a continuum approach, is shown to essentially coincide with the upper H-S bound, thereby proving that the commonly made assumption that Snow's equation is an "upper bound" is indeed correct. This problem is actually characterized by two small parameters, the aspect ratio of the spheroidal fractures, α, and the permeability ratio, κ = km/kf. Two different regimes can be identified, corresponding to α < κ and κ < α, and expressions for each of the effective medium approximations are developed in both regimes. In both regimes, the symmetric version of the self-consistent approximation is the most accurate.

Strategies for waste management in small and medium towns of developing countries: a case study of India.

PubMed

Sundaravadivel, M; Vigneswaran, S

2003-01-01

This paper evaluates the issues of waste management in small and medium towns (SMTs) (with population in the range of 10,000-100,000) of India, and identifies the need for a multi-disciplinary approach encompassing technological, economic and financial aspects of the issues to effect improvements. A comprehensive set of cross-disciplinary strategies is suggested to improve the prevailing conditions with environmentally appropriate, economically efficient and financially self-sustaining waste management services. Based on a case study of four SMTs in the State of Tamil Nadu in India, this paper evaluates the application of the suggested strategies and offers policy recommendations.

Heat transfer in porous medium embedded with vertical plate: Non-equilibrium approach - Part B

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

Quadir, G. A., E-mail: Irfan-magami@Rediffmail.com, E-mail: gaquadir@gmail.com; Badruddin, Irfan Anjum

2016-06-08

This work is continuation of the paper Part A. Due to large number of results, the paper is divided into two section with section-A (Part A) discussing the effect of various parameters such as heat transfer coefficient parameter, thermal conductivity ratio etc. on streamlines and isothermal lines. Section-B highlights the heat transfer characteristics in terms of Nusselt number The Darcy model is employed to simulate the flow inside the medium. It is assumed that the heat transfer takes place by convection and radiation. The governing partial differential equations are converted into non-dimensional form and solved numerically using finite element method.

A time-domain method for prediction of noise radiated from supersonic rotating sources in a moving medium

NASA Astrophysics Data System (ADS)

Huang, Zhongjie; Siozos-Rousoulis, Leonidas; De Troyer, Tim; Ghorbaniasl, Ghader

2018-02-01

This paper presents a time-domain method for noise prediction of supersonic rotating sources in a moving medium. The proposed approach can be interpreted as an extensive time-domain solution for the convected permeable Ffowcs Williams and Hawkings equation, which is capable of avoiding the Doppler singularity. The solution requires special treatment for construction of the emission surface. The derived formula can explicitly and efficiently account for subsonic uniform constant flow effects on radiated noise. Implementation of the methodology is realized through the Isom thickness noise case and high-speed impulsive noise prediction from helicopter rotors.

Calculation of Transfer Functions of Multilayer Biotissues in the Problems of Correction of Their Fluorescence Spectra

NASA Astrophysics Data System (ADS)

Lysenko, S. A.

2018-01-01

A method for rapid calculation of a flux of stimulated fluorescence of a multilayer optically dense medium with inhomogeneous distribution of the fluorophore has been developed. The light field in the medium at the excitation wavelength of fluorescence is represented by a superposition of incident collimated, incident diffuse, and reflected diffuse fluxes. A two-stream approximation is used to describe the light field in the medium at the wavelength of emission of the fluorescence. Fluxes in adjacent elementary layers of the medium and on its surface are connected by simple matrix operators that are obtained using a combination of engineering approaches of radiation-transfer theory and single-scattering approximation. The calculations of fluorescence fluxes of a four-layer biotissue that are excited and recorded at 400-800 nm are compared with their Monte Carlo simulation with a discrepancy of 1%. The effect of the propagation medium on the fluorescence spectra of 5-ALA-induced protoporphyrin IX that are recorded from human skin was studied, and a technique for their correction that is based on measurements and quantitative analysis of the diffuse reflectance spectrum of skin was proposed.

Medium modified two-body scattering amplitude from proton-nucleus total cross-sections

NASA Technical Reports Server (NTRS)

Tripathi, R. K.; Wilson, J. W.; Cucinotta, F. A.

2001-01-01

Recently (R.K. Tripathi, J.W. Wilson, F.A. Cucinotta, Nucl. Instr. and Meth. B 145 (1998) 277; R.K. Tripathi, F.A. Cucinotta, J.W. Wilson, NASA-TP-1998-208438), we have extracted nucleon-nucleon (N-N) cross-sections in the medium directly from experiment. The in-medium N-N cross-sections form the basic ingredients of several heavy-ion scattering approaches including the coupled-channel approach developed at the NASA Langley Research Center. Here, we investigate the ratio of real to imaginary part of the two-body scattering amplitude in the medium. These ratios are used in combination with the in-medium N-N cross-sections to calculate total proton-nucleus cross-sections. The agreement is excellent with the available experimental data. These cross-sections are needed for the radiation risk assessment of space missions. c2001 Elsevier Science B.V. All rights reserved.

Velocity sensitivity of seismic body waves to the anisotropic parameters of a TTI-medium

NASA Astrophysics Data System (ADS)

Zhou, Bing; Greenhalgh, Stewart

2008-09-01

We formulate the derivatives of the phase and group velocities for each of the anisotropic parameters in a tilted transversely isotropic medium (TTI-medium). This is a common geological model in seismic exploration and has five elastic moduli or related Thomsen parameters and two orientation angles defining the axis of symmetry of the rock. We present two independent methods to compute the derivatives and examine the formulae with real anisotropic rocks. The formulations and numerical computations do not encounter any singularity problem when applied to the two quasi shear waves, which is a problem with other approaches. The two methods yield the same results, which show in a quantitative way the sensitivity behaviour of the phase and the group velocities to all of the elastic moduli or Thomsen's anisotropic parameters as well as the orientation angles in the 2D and 3D cases. One can recognize the dominant (strong effect) and weak (or 'dummy') parameters for the three seismic body-wave modes (qP, qSV, qSH) and their effective domains over the whole range of phase-slowness directions. These sensitivity patterns indicate the possibility of nonlinear kinematic inversion with the three wave modes for determining the anisotropic parameters and imaging an anisotropic medium.

REVIEWS OF TOPICAL PROBLEMS The quark-gluon medium

NASA Astrophysics Data System (ADS)

Dremin, Igor M.; Leonidov, Andrei V.

2011-02-01

The properties of the quark-gluon medium observed in high-energy nucleus-nucleus collisions are discussed. The main experimental facts about these collisions are briefly described and compared with data about proton-proton collisions. Both microscopic and macroscopic approaches to their description are reviewed. The chromodynamics of the quark-gluon medium at high energies is mainly considered. The energy loss of partons moving in this medium is treated. The principal conclusion is that the medium possesses some collective properties which are crucial for understanding the experimental observations.

Surface waves on multilayer hyperbolic metamaterials: Operator approach to effective medium approximation

NASA Astrophysics Data System (ADS)

Popov, Vladislav; Lavrinenko, Andrei V.; Novitsky, Andrey

2018-03-01

In this paper, we elaborate on the operator effective medium approximation developed recently in Popov et al. [Phys. Rev. B 94, 085428 (2016), 10.1103/PhysRevB.94.085428] to get insight into the surface polariton excitation at the interface of a multilayer hyperbolic metamaterial (HMM). In particular, we find that HMMs with bilayer unit cells support the TE- and TM-polarized surface waves beyond the Maxwell Garnett approximation due to the spatial dispersion interpreted as effective magnetoelectric coupling. The latter is also responsible for the dependence of surface wave propagation on the order of layers in the unit cell. Elimination of the magnetoelectric coupling in three-layer unit cells complying with inversion symmetry restores the qualitative regularity of the Maxwell Garnett approximation, as well as strongly suppresses the influence of the order of layers in the unit cell.

Quantitative modeling of coupled piezo-elastodynamic behavior of piezoelectric actuators bonded to an elastic medium for structural health monitoring: a review.

PubMed

Huang, Guoliang; Song, Fei; Wang, Xiaodong

2010-01-01

Elastic waves, especially guided waves, generated by a piezoelectric actuator/sensor network, have shown great potential for on-line health monitoring of advanced aerospace, nuclear, and automotive structures in recent decades. Piezoelectric materials can function as both actuators and sensors in these applications due to wide bandwidth, quick response and low costs. One of the most fundamental issues surrounding the effective use of piezoelectric actuators is the quantitative evaluation of the resulting elastic wave propagation by considering the coupled piezo-elastodynamic behavior between the actuator and the host medium. Accurate characterization of the local interfacial stress distribution between the actuator and the host medium is the key issue for the problem. This paper presents a review of the development of analytical, numerical and hybrid approaches for modeling of the coupled piezo-elastodynamic behavior. The resulting elastic wave propagation for structural health monitoring is also summarized.

Medium-induced change of the optical response of metal clusters in rare-gas matrices

NASA Astrophysics Data System (ADS)

Xuan, Fengyuan; Guet, Claude

2017-10-01

Interaction with the surrounding medium modifies the optical response of embedded metal clusters. For clusters from about ten to a few hundreds of silver atoms, embedded in rare-gas matrices, we study the environment effect within the matrix random phase approximation with exact exchange (RPAE) quantum approach, which has proved successful for free silver clusters. The polarizable surrounding medium screens the residual two-body RPAE interaction, adds a polarization term to the one-body potential, and shifts the vacuum energy of the active delocalized valence electrons. Within this model, we calculate the dipole oscillator strength distribution for Ag clusters embedded in helium droplets, neon, argon, krypton, and xenon matrices. The main contribution to the dipole surface plasmon red shift originates from the rare-gas polarization screening of the two-body interaction. The large size limit of the dipole surface plasmon agrees well with the classical prediction.

Flow-Signature Analysis of Water Consumption in Nonresidential Building Water Networks Using High-Resolution and Medium-Resolution Smart Meter Data: Two Case Studies

NASA Astrophysics Data System (ADS)

Clifford, Eoghan; Mulligan, Sean; Comer, Joanne; Hannon, Louise

2018-01-01

Real-time monitoring of water consumption activities can be an effective mechanism to achieve efficient water network management. This approach, largely enabled by the advent of smart metering technologies, is gradually being practiced in domestic and industrial contexts. In particular, identifying water consumption habits from flow-signatures, i.e., the specific end-usage patterns, is being investigated as a means for conservation in both the residential and nonresidential context. However, the quality of meter data is bivariate (dependent on number of meters and data temporal resolution) and as a result, planning a smart metering scheme is relatively difficult with no generic design approach available. In this study, a comprehensive medium-resolution to high-resolution smart metering program was implemented at two nonresidential trial sites to evaluate the effect of spatial and temporal data aggregation. It was found that medium-resolution water meter data were capable of exposing regular, continuous, peak use, and diurnal patterns which reflect group wide end-usage characteristics. The high-resolution meter data permitted flow-signature at a personal end-use level. Through this unique opportunity to observe water usage characteristics via flow-signature patterns, newly defined hydraulic-based design coefficients determined from Poisson rectangular pulse were developed to intuitively aid in the process of pattern discovery with implications for automated activity recognition applications. A smart meter classification and siting index was introduced which categorizes meter resolution in terms of their suitable application.

A Multivariate Approach to Evaluate Biomass Production, Biochemical Composition and Stress Compounds of Spirulina platensis Cultivated in Wastewater.

PubMed

Çelekli, Abuzer; Topyürek, Ali; Markou, Giorgos; Bozkurt, Hüseyin

2016-10-01

The study was performed to investigate the effects of using cow effluent for the cultivation of Spirulina platensis on its biomass production and cell physiology. S. platensis was cultivated in three different cow effluents (CE) used as cultivation medium during 15 days. CE was prepared using dry cow manures, and it was further modified with supplement of NaNO 3 (CEN) and NaNO 3  + NaCl (CENS). High nitrate value stimulated chlorophyll-a and total protein content of the cyanobacterium and also biomass production in standards medium (SM) and CEN media. Total carbohydrate content of S. platensis grown in CE media was found to be higher (p < 0.05) than that of SM. Productions of biomass and biochemical compounds by the cyanobacterium grown on the CE and SM media were evaluated by using multivariate approach. Conductivity, oxidation reduction potential (ORP), salinity, pH, and TDS played important role (p < 0.01) in the biochemical composition. As an effective explanatory factor, ORP had a significant positive correlation with H 2 O 2 , whereas negatively correlated with chlorophyll-α, biomass production, filament length, and proline. Canonical correspondence analysis proposed that biochemical compounds of S. platensis were not only affected by salinity and nutrition of media but also by pH and ORP. The present study indicated that CEN as a low cost model medium had high potential for the production of biomass by S. platensis with high protein content.

Grafilm; An Approach to a New Medium.

ERIC Educational Resources Information Center

Bryne-Daniel, J.

"Grafilm" is a new medium which combines a variety of graphic and illustrative techniques on film stock. For example, by drawing on film it is possible to create a new type of animation. The emphasis in this book is on a graphic/poetic approach to film-making rather than a photographic/prosaic one. The book consists of a series of projects which…

The Better Beginnings, Better Futures Project: Findings from Grade 3 to Grade 9

ERIC Educational Resources Information Center

Peters, Ray DeV.; Bradshaw, Alison J.; Petrunka, Kelly; Nelson, Geoffrey; Herry, Yves; Craig, Wendy M.; Arnold, Robert; Parker, Kevin C. H.; Khan, Shahriar R.; Hoch, Jeffrey S.; Pancer, S. Mark; Loomis, Colleen; Belanger, Jean-Marc; Evers, Susan; Maltais, Claire; Thompson, Katherine; Rossiter, Melissa D.

2010-01-01

Although comprehensive and ecological approaches to early childhood prevention are commonly advocated, there are few examples of long-term follow-up of such programs. In this monograph, we investigate the medium- and long-term effects of an ecological, community-based prevention project for primary school children and families living in three…

From Starter to Finish: Producing Sourdough Breads to Illustrate the Use of Industrial Microorganisms

ERIC Educational Resources Information Center

Wagner, Stephen C.

2005-01-01

An approach where students first develop and make a medium to grow an Lactobacillus sanfranciscensis (LS) strain, the bacterium used to make San Francisco sourdough bread is described. It offers an effective and donable strategy to teach about industrial microbiology process and the types of organisms used in these endeavors.

The Educational Impact of Online Learning: How Do University Students Perform in Subsequent Courses?

ERIC Educational Resources Information Center

Krieg, John M.; Henson, Steven E.

2016-01-01

Using a large student-level dataset from a medium-sized regional comprehensive university, we measure the impact of taking an online prerequisite course on follow-up course grades. To control for self-selection into online courses, we utilize student, instructor, course, and time fixed effects augmented with an instrumental variable approach. We…

Science Communication Through Art: Objectives, Challenges, and Outcomes.

PubMed

Lesen, Amy E; Rogan, Ama; Blum, Michael J

2016-09-01

The arts are becoming a favored medium for conveying science to the public. Tracking trending approaches, such as community-engaged learning, alongside challenges and goals can help establish metrics to achieve more impactful outcomes, and to determine the effectiveness of arts-based science communication for raising awareness or shaping public policy. Copyright © 2016 Elsevier Ltd. All rights reserved.

Developing an Approach for Comparing Students' Multimodal Text Creations: A Case Study

ERIC Educational Resources Information Center

Levy, Mike; Kimber, Kay

2009-01-01

Classroom teachers routinely make judgments on the quality of their students' work based on their recognition of how effectively the student has assembled key features of the genre or the medium. Yet how readily can teachers talk about the features of student-created multimodal texts in ways that can improve learning and performance? This article…

Determining Responsiveness to Tier 2 Intervention in Response to Intervention: Level of Performance, Growth, or Both

ERIC Educational Resources Information Center

Milburn, Trelani F.; Lonigan, Christopher J.; Phillips, Beth M.

2017-01-01

This response to intervention study examined agreement between classification methods of preschool children's responsiveness to Tier 2 intervention using level of performance (25th percentile), growth (equivalent to small and medium effect sizes), and both level of performance and growth in a dual-discrepancy approach. Overall, 181 children…

The Relation between Mastery Goals and Intrinsic Motivation among University Students: A Longitudinal Study

ERIC Educational Resources Information Center

Bieg, Sonja; Reindl, Marion; Dresel, Markus

2017-01-01

The present work broadens previous research on students' mastery goals and intrinsic motivation by exploring their reciprocal effects using a longitudinal approach. To this end, a study using four measurement points was conducted during 10 weeks of one semester. The sample comprised 1156 students enrolled in psychology courses at a medium-sized…

Mechanism-based strategies for protein thermostabilization.

PubMed

Mozhaev, V V

1993-03-01

Strategies for stabilizing enzymes can be derived from a two-step model of irreversible inactivation that involves preliminary reversible unfolding, followed by an irreversible step. Reversible unfolding is best prevented by covalent immobilization, whereas methods such as covalent modification of amino acid residues or 'medium engineering' (by the addition of low-molecular-weight compounds) are effective against irreversible 'incorrect' refolding. Genetic modification of the protein sequence is the most effective approach for preventing chemical deterioration.

Intrinsic Multi-Scale Dynamic Behaviors of Complex Financial Systems

PubMed Central

Ouyang, Fang-Yan; Zheng, Bo; Jiang, Xiong-Fei

2015-01-01

The empirical mode decomposition is applied to analyze the intrinsic multi-scale dynamic behaviors of complex financial systems. In this approach, the time series of the price returns of each stock is decomposed into a small number of intrinsic mode functions, which represent the price motion from high frequency to low frequency. These intrinsic mode functions are then grouped into three modes, i.e., the fast mode, medium mode and slow mode. The probability distribution of returns and auto-correlation of volatilities for the fast and medium modes exhibit similar behaviors as those of the full time series, i.e., these characteristics are rather robust in multi time scale. However, the cross-correlation between individual stocks and the return-volatility correlation are time scale dependent. The structure of business sectors is mainly governed by the fast mode when returns are sampled at a couple of days, while by the medium mode when returns are sampled at dozens of days. More importantly, the leverage and anti-leverage effects are dominated by the medium mode. PMID:26427063

Finite-element solution to multidimensional multisource electromagnetic problems in the frequency domain using non-conforming meshes

NASA Astrophysics Data System (ADS)

Soloveichik, Yury G.; Persova, Marina G.; Domnikov, Petr A.; Koshkina, Yulia I.; Vagin, Denis V.

2018-03-01

We propose an approach to solving multisource induction logging problems in multidimensional media. According to the type of induction logging tools, the measurements are performed in the frequency range of 10 kHz to 14 MHz, transmitter-receiver offsets vary in the range of 0.5-8 m or more, and the trajectory length is up to 1 km. For calculating the total field, the primary-secondary field approach is used. The secondary field is calculated with the use of the finite-element method (FEM), irregular non-conforming meshes with local refinements and a direct solver. The approach to constructing basis functions with the continuous tangential components (from Hcurl(Ω)) on the non-conforming meshes from the standard shape vector functions is developed. On the basis of this method, the algorithm of generating global matrices and a vector of the finite-element equation system is proposed. We also propose the method of grouping the logging tool positions, which makes it possible to significantly increase the computational effectiveness. This is achieved due to the compromise between the possibility of using the 1-D background medium, which is very similar to the investigated multidimensional medium for a small group, and the decrease in the number of the finite-element matrix factorizations with the increasing number of tool positions in one group. For calculating the primary field, we propose the method based on the use of FEM. This method is highly effective when the 1-D field is required to be calculated at a great number of points. The use of this method significantly increases the effectiveness of the primary-secondary field approach. The proposed approach makes it possible to perform modelling both in the 2.5-D case (i.e. without taking into account a borehole and/or invasion zone effect) and the 3-D case (i.e. for models with a borehole and invasion zone). The accuracy of numerical results obtained with the use of the proposed approach is compared with the one obtained by other codes for 1-D and 3-D anisotropic models. The results of this comparison lend support to the validity of our code. We also present the numerical results proving greater effectiveness of the finite-element approach proposed for calculating the 1-D field in comparison with the known codes implementing the semi-analytical methods for the case in which the field is calculated at a large number of points. Additionally, we present the numerical results which confirm the accuracy advantages of the automatic choice of a background medium for calculating the 1-D field as well as the results of 2.5-D modelling for a geoelectrical model with anisotropic layers, a fault and long tool-movement trajectory with the varying dip angle.

Quantifying the Availability of Vertebrate Hosts to Ticks: A Camera-Trapping Approach

PubMed Central

Hofmeester, Tim R.; Rowcliffe, J. Marcus; Jansen, Patrick A.

2017-01-01

The availability of vertebrate hosts is a major determinant of the occurrence of ticks and tick-borne zoonoses in natural and anthropogenic ecosystems and thus drives disease risk for wildlife, livestock, and humans. However, it remains challenging to quantify the availability of vertebrate hosts in field settings, particularly for medium-sized to large-bodied mammals. Here, we present a method that uses camera traps to quantify the availability of warm-bodied vertebrates to ticks. The approach is to deploy camera traps at questing height at a representative sample of random points across the study area, measure the average photographic capture rate for vertebrate species, and then correct these rates for the effective detection distance. The resulting “passage rate” is a standardized measure of the frequency at which vertebrates approach questing ticks, which we show is proportional to contact rate. A field test across twenty 1-ha forest plots in the Netherlands indicated that this method effectively captures differences in wildlife assemblage composition between sites. Also, the relative abundances of three life stages of the sheep tick Ixodes ricinus from drag sampling were correlated with passage rates of deer, which agrees with the known association with this group of host species, suggesting that passage rate effectively reflects the availability of medium- to large-sized hosts to ticks. This method will facilitate quantitative studies of the relationship between densities of questing ticks and the availability of different vertebrate species—wild as well as domesticated species—in natural and anthropogenic settings. PMID:28770219

Optical extinction of highly porous aerosol following atmospheric freeze drying

NASA Astrophysics Data System (ADS)

Adler, Gabriela; Haspel, Carynelisa; Moise, Tamar; Rudich, Yinon

2014-06-01

Porous glassy particles are a potentially significant but unexplored component of atmospheric aerosol that can form by aerosol processing through the ice phase of high convective clouds. The optical properties of porous glassy aerosols formed from a freeze-dry cycle simulating freezing and sublimation of ice particles were measured using a cavity ring down aerosol spectrometer (CRD-AS) at 532 nm and 355 nm wavelength. The measured extinction efficiency was significantly reduced for porous organic and mixed organic-ammonium sulfate particles as compared to the extinction efficiency of the homogeneous aerosol of the same composition prior to the freeze-drying process. A number of theoretical approaches for modeling the optical extinction of porous aerosols were explored. These include effective medium approximations, extended effective medium approximations, multilayer concentric sphere models, Rayleigh-Debye-Gans theory, and the discrete dipole approximation. Though such approaches are commonly used to describe porous particles in astrophysical and atmospheric contexts, in the current study, these approaches predicted an even lower extinction than the measured one. Rather, the best representation of the measured extinction was obtained with an effective refractive index retrieved from a fit to Mie scattering theory assuming spherical particles with a fixed void content. The single-scattering albedo of the porous glassy aerosols was derived using this effective refractive index and was found to be lower than that of the corresponding homogeneous aerosol, indicating stronger relative absorption at the wavelengths measured. The reduced extinction and increased absorption may be of significance in assessing direct, indirect, and semidirect forcing in regions where porous aerosols are expected to be prevalent.

From medium heterogeneity to flow and transport: A time-domain random walk approach

NASA Astrophysics Data System (ADS)

Hakoun, V.; Comolli, A.; Dentz, M.

2017-12-01

The prediction of flow and transport processes in heterogeneous porous media is based on the qualitative and quantitative understanding of the interplay between 1) spatial variability of hydraulic conductivity, 2) groundwater flow and 3) solute transport. Using a stochastic modeling approach, we study this interplay through direct numerical simulations of Darcy flow and advective transport in heterogeneous media. First, we study flow in correlated hydraulic permeability fields and shed light on the relationship between the statistics of log-hydraulic conductivity, a medium attribute, and the flow statistics. Second, we determine relationships between Eulerian and Lagrangian velocity statistics, this means, between flow and transport attributes. We show how Lagrangian statistics and thus transport behaviors such as late particle arrival times are influenced by the medium heterogeneity on one hand and the initial particle velocities on the other. We find that equidistantly sampled Lagrangian velocities can be described by a Markov process that evolves on the characteristic heterogeneity length scale. We employ a stochastic relaxation model for the equidistantly sampled particle velocities, which is parametrized by the velocity correlation length. This description results in a time-domain random walk model for the particle motion, whose spatial transitions are characterized by the velocity correlation length and temporal transitions by the particle velocities. This approach relates the statistical medium and flow properties to large scale transport, and allows for conditioning on the initial particle velocities and thus to the medium properties in the injection region. The approach is tested against direct numerical simulations.

Capillary-tube-based extension of thermoacoustic theory for a random medium

NASA Astrophysics Data System (ADS)

Roh, Heui-Seol; Raspet, Richard; Bass, Henry E.

2005-09-01

Thermoacoustic theory for a single capillary tube is extended to random bulk medium on the basis of capillary tubes. The characteristics of the porous stack inside the resonator such as the tortuosity, dynamic shape factor, and porosity are introduced for the extension of wave equation by following Attenborough's approach. Separation of the dynamic shape factor for the viscous and thermal effect is adopted and scaling using the dynamic shape factor and tortuosity factor is demonstrated. The theoretical and experimental comparison of thermoviscous functions in reticulated vitreous carbon (RVC) and aluminum foam shows reasonable agreement. The extension is useful for investigations of the properties of a stack with arbitrary shapes of non-parallel pores.

Effective viscoelastic properties of shales.

NASA Astrophysics Data System (ADS)

Cornet, Jan; Dabrowski, Marcin; Schmid, Daniel

2017-04-01

Shales are often characterized as being elasto-plastic: they deform elastically for stresses below a certain yield and plastically at the limit. This approach dismisses any time dependent behavior that occurs in nature. Our goal is to better understand this time dependency by considering the visco-elastic behavior of shales before plasticity is reached. Shales are also typically heterogeneous and the question arises as to how to derive their effective properties in order to model them as a homogeneous medium. We model shales using inclusion based models due to their versatility and their ability to represent the microstructure. The inclusions represent competent quartz or calcite grains which are set in a viscous matrix made of clay minerals. Our approach relies on both numerical and analytical results in two dimension and we use them to cross check each other. The numerical results are obtained using MILAMIN, a fast-finite element solver for large problems, while the analytical solutions are based on the correspondence principle of linear viscoelasticity. This principle allows us to use the results on effective properties already derived for elastic bodies and to adapt them to viscoelastic bodies. We start by revisiting the problem of a single inclusion in an infinite medium and then move on to consider many inclusions.

Structural Engineering of Nanoporous Anodic Alumina Photonic Crystals by Sawtooth-like Pulse Anodization.

PubMed

Law, Cheryl Suwen; Santos, Abel; Nemati, Mahdieh; Losic, Dusan

2016-06-01

This study presents a sawtooth-like pulse anodization approach aiming to create a new type of photonic crystal structure based on nanoporous anodic alumina. This nanofabrication approach enables the engineering of the effective medium of nanoporous anodic alumina in a sawtooth-like manner with precision. The manipulation of various anodization parameters such as anodization period, anodization amplitude, number of anodization pulses, ramp ratio and pore widening time allows a precise control and fine-tuning of the optical properties (i.e., characteristic transmission peaks and interferometric colors) exhibited by nanoporous anodic alumina photonic crystals (NAA-PCs). The effect of these anodization parameters on the photonic properties of NAA-PCs is systematically evaluated for the establishment of a fabrication methodology toward NAA-PCs with tunable optical properties. The effective medium of the resulting NAA-PCs is demonstrated to be optimal for the development of optical sensing platforms in combination with reflectometric interference spectroscopy (RIfS). This application is demonstrated by monitoring in real-time the formation of monolayers of thiol molecules (11-mercaptoundecanoic acid) on the surface of gold-coated NAA-PCs. The obtained results reveal that the adsorption mechanism between thiol molecules and gold-coated NAA-PCs follows a Langmuir isotherm model, indicating a monolayer sorption mechanism.

Effects of Bacteria on Artemia franciscana Cultured in Different Gnotobiotic Environments

PubMed Central

Marques, Antonio; Dinh, Thi; Ioakeimidis, Christos; Huys, Geert; Swings, Jean; Verstraete, Willy; Dhont, Jean; Sorgeloos, Patrick; Bossier, Peter

2005-01-01

The use of probiotics is receiving considerable attention as an alternative approach to control microbiota in aquaculture farms, especially in hatching facilities. However, application with consistent results is hampered by insufficient information on their modes of action. To investigate whether dead bacteria (allowing investigation of their nutritional effect) or live bacteria (allowing evaluation of their probiotic effect) have any beneficial effect towards Artemia franciscana and, subsequently, if live bacteria have probiotic effects beyond the effects observed with dead bacteria, a model system was employed using gnotobiotic Artemia as a test organism. Nauplii were cultured in the presence of 10 bacterial strains combined with four different major axenic live feeds (two strains of Saccharomyces cerevisiae and two strains of Dunaliella tertiolecta) differing in their nutritional values. In combination with poor- and medium-quality live feeds, dead bacteria exerted a strong effect on Artemia survival but a rather weak or no effect on individual length and constituted a maximum of only 5.9% of the total ash-free dry weight supplied. These effects were reduced or even disappeared when medium- to good-quality major feed sources were used, possibly due to improvements in the health status of Artemia. Some probiotic bacteria, such as GR 8 (Cytophaga spp.), improved (not always significantly) the performance of nauplii beyond the effect observed with dead bacteria, independently of the feed supplied. The present approach can be an excellent system to study the exact mode of action of bacteria, especially if combined with challenge tests or other types of analysis (e.g., transcriptome and proteonomic analysis). PMID:16085818

Medium optimization for the production of recombinant nattokinase by Bacillus subtilis using response surface methodology.

PubMed

Chen, Po Ting; Chiang, Chung-Jen; Chao, Yun-Peng

2007-01-01

Nattokinase is a potent fibrinolytic enzyme with the potential for fighting cardiovascular diseases. Most recently, a new Bacillus subtilis/Escherichia coli (B. subtilis/E. coli) shuttle vector has been developed to achieve stable production of recombinant nattokinase in B. subtilis (Chen; et al. 2007, 23, 808-813). With this developed B. subtilis strain, the design of an optimum but cost-effective medium for high-level production of recombinant nattokinase was attempted by using response surface methodology. On the basis of the Plackett-Burman design, three critical medium components were selected. Subsequently, the optimum combination of selected factors was investigated by the Box-Behnken design. As a result, it gave the predicted maximum production of recombinant nattokinase with 71 500 CU/mL for shake-flask cultures when the concentrations of soybean hydrolysate, potassium phosphate, and calcium chloride in medium were at 6.100, 0.415, and 0.015%, respectively. This was further verified by a duplicated experiment. Moreover, the production scheme based on the optimum medium was scaled up in a fermenter. The batch fermentation of 3 L was carried out by controlling the condition at 37 degrees C and dissolved oxygen reaching 20% of air saturation level while the fermentation pH was initially set at 8.5. Without the need for controlling the broth pH, recombinant nattokinase production with a yield of 77 400 CU/mL (corresponding to 560 mg/L) could be obtained in the culture broth within 24 h. In particular, the recombinant B. subtilis strain was found fully stable at the end of fermentation when grown on the optimum medium. Overall, it indicates the success of this experimental design approach in formulating a simple and cost-effective medium, which provides the developed strain with sufficient nutrient supplements for stable and high-level production of recombinant nattokinase in a fermenter.

Acoustic metamaterials with broadband and wide-angle impedance matching

NASA Astrophysics Data System (ADS)

Liu, Chenkai; Luo, Jie; Lai, Yun

2018-04-01

We propose a general approach to design broadband and wide-angle impedance-matched acoustic metamaterials. Such an unusual acoustic impedance matching characteristic can be well explained by using a spatially dispersive effective medium theory. For demonstrations, we used silicone rubber, which has a huge impedance contrast with water, to design one- and two-dimensional acoustic structures which are almost perfectly impedance matched to water for a wide range of incident angles and in a broad frequency band. Our work opens up an approach to realize extraordinary acoustic impedance matching properties via metamaterial-design techniques.

Photonic band gap effect and structural color from silver nanoparticle gelatin emulsion

NASA Astrophysics Data System (ADS)

Kok, Mang Hin; Ma, Rui; Lee, Jeffrey Chi Wai; Tam, Wing Yim; Chan, C. T.; Sheng, Ping; Cheah, Kok Wai

2005-10-01

We have fabricated planar structures of silver nanoparticles in monochromatic gelatin emulsion with a continuous spacing ranging from 0.15-0.40 micron using a two-beam interference of a single laser source. Our planar holograms display a colorful “rainbow” pattern and photonic bandgaps covering the visible and IR ranges. We model the planar silver nanoparticle-gelatin composite system using an effective medium approach and good agreement is obtained between theory and experiment.

WIKI-Enhanced Scaffolding to Encourage Student Participation in a Content and Language Integrated Learning (CLIL) Classroom

ERIC Educational Resources Information Center

Lin, Chun-Yi

2014-01-01

Given the fact that more and more universities stress on using English as medium to teach students with diverse backgrounds, the content and language integrated learning approach (CLIL) is now frequently introduced to faculty to support effective instruction and learning. Inspired by a CLIL workshop I attended, in which the instructor offered an…

Gas hydrate cool storage system

DOEpatents

Ternes, Mark P.; Kedl, Robert J.

1985-01-01

This invention is a process for formation of a gas hydrate to be used as a cool storage medium using a refrigerant in water. Mixing of the immiscible refrigerant and water is effected by addition of a surfactant and agitation. The difficult problem of subcooling during the process is overcome by using the surfactant and agitation and performance of the process significantly improves and approaches ideal.

The Multi-Frequency Correlation Between Eua and sCER Futures Prices: Evidence from the Emd Approach

NASA Astrophysics Data System (ADS)

Zhang, Yue-Jun; Huang, Yi-Song

2015-05-01

Currently European Union Allowances (EUA) and secondary Certified Emission Reduction (sCER) have become two dominant carbon trading assets for investors and their linkage attracts much attention from academia and practitioners in recent years. Under this circumstance, we use the empirical mode decomposition (EMD) approach to decompose the two carbon futures contract prices and discuss their correlation from the multi-frequency perspective. The empirical results indicate that, first, the EUA and sCER futures price movements can be divided into those triggered by the long-term, medium-term and short-term market impacts. Second, the price movements in the EUA and sCER futures markets are primarily caused by the long-term impact, while the short-term impact can only explain a small fraction. Finally, the long-term (short-term) effect on EUA prices is statistically uncorrelated with the short-term (long-term) effect of sCER prices, and there is a medium or strong lead-and-lag correlation between the EUA and sCER price components with the same time scales. These results may provide some important insights of price forecast and arbitraging activities for carbon futures market investors, analysts and regulators.

Mitigation of multipath effect in GNSS short baseline positioning by the multipath hemispherical map

NASA Astrophysics Data System (ADS)

Dong, D.; Wang, M.; Chen, W.; Zeng, Z.; Song, L.; Zhang, Q.; Cai, M.; Cheng, Y.; Lv, J.

2016-03-01

Multipath is one major error source in high-accuracy GNSS positioning. Various hardware and software approaches are developed to mitigate the multipath effect. Among them the MHM (multipath hemispherical map) and sidereal filtering (SF)/advanced SF (ASF) approaches utilize the spatiotemporal repeatability of multipath effect under static environment, hence they can be implemented to generate multipath correction model for real-time GNSS data processing. We focus on the spatial-temporal repeatability-based MHM and SF/ASF approaches and compare their performances for multipath reduction. Comparisons indicate that both MHM and ASF approaches perform well with residual variance reduction (50 %) for short span (next 5 days) and maintains roughly 45 % reduction level for longer span (next 6-25 days). The ASF model is more suitable for high frequency multipath reduction, such as high-rate GNSS applications. The MHM model is easier to implement for real-time multipath mitigation when the overall multipath regime is medium to low frequency.

Fluorescent chemosensor based on urea/thiourea moiety for sensing of Hg(II) ions in an aqueous medium with high sensitivity and selectivity: A comparative account on effect of molecular architecture on chemosensing

NASA Astrophysics Data System (ADS)

Mishra, Jayanti; Kaur, Harpreet; Ganguli, Ashok K.; Kaur, Navneet

2018-06-01

Mercury is a well-known heavy metal ion which is extremely poisonous to health but is still employed in the form of mercury salts and organomercury compounds in various industrial, anthropological and agricultural activities. Henceforth, its sensing in aqueous medium is an area of great interest in order to avoid its hazardous effect. In the present manuscript, urea/thiourea linkage bearing four organic ligands (1a, 1b, 2a and 2b) are synthesized by a three-step synthetic approach. The organic ligands were then employed to develop organic nanoparticles by re-precipitation method which was further probed for their selective recognition behavior in an aqueous medium using fluorescence spectroscopy. The fluorescence emission profile of the ONPs is used as a tool for the tracking of sensing behavior. The ONPs of 1b has shown selective recognition towards Hg(II) in aqueous medium evidenced by enhancement of fluorescence emission intensity after complexation of 1b ONP with Hg(II), among several alkali, alkaline earth and transition metal ions with a detection limit of the order of 0.84 μM. The ability of the proposed sensor to sense Hg(II) ions with high selectivity and sensitivity could be accounted to photo-induced electron transfer (PET) "OFF" mechanism at λem = 390 nm. This study reveals the application of the proposed thiourea-based sensor for the selective recognition of the Hg(II) ions in an aqueous medium.

Taurine Biosynthesis in a Fish Liver Cell Line (ZFL) Adapted to a Serum-Free Medium

PubMed Central

Liu, Chieh-Lun; Watson, Aaron M.; Place, Allen R.; Jagus, Rosemary

2017-01-01

Although taurine has been shown to play multiple important physiological roles in teleosts, little is known about the molecular mechanisms underlying dietary requirements. Cell lines can provide useful tools for deciphering biosynthetic pathways and their regulation. However, culture media and sera contain variable taurine levels. To provide a useful cell line for the investigation of taurine homeostasis, an adult zebrafish liver cell line (ZFL) has been adapted to a taurine-free medium by gradual accommodation to a commercially available synthetic medium, UltraMEM™-ITES. Here we show that ZFL cells are able to synthesize taurine and be maintained in medium without taurine. This has allowed for the investigation of the effects of taurine supplementation on cell growth, cellular amino acid pools, as well as the expression of the taurine biosynthetic pathway and taurine transporter genes in a defined fish cell type. After taurine supplementation, cellular taurine levels increase but hypotaurine levels stay constant, suggesting little suppression of taurine biosynthesis. Cellular methionine levels do not change after taurine addition, consistent with maintenance of taurine biosynthesis. The addition of taurine to cells grown in taurine-free medium has little effect on transcript levels of the biosynthetic pathway genes for cysteine dioxygenase (CDO), cysteine sulfinate decarboxylase (CSAD), or cysteamine dioxygenase (ADO). In contrast, supplementation with taurine causes a 30% reduction in transcript levels of the taurine transporter, TauT. This experimental approach can be tailored for the development of cell lines from aquaculture species for the elucidation of their taurine biosynthetic capacity. PMID:28587087

Comparative metabolomics reveals the mechanism of avermectin production enhancement by S-adenosylmethionine.

PubMed

Tian, Pingping; Cao, Peng; Hu, Dong; Wang, Depei; Zhang, Jian; Wang, Lin; Zhu, Yan; Gao, Qiang

2017-05-01

It was found that S-adenosylmethionine (SAM) could effectively improve avermectin titer with 30-60 μg/mL addition to FH medium. To clearly elucidate the mechanism of SAM on intracellular metabolites of Streptomyces avermitilis, a GC-MS-based comparative metabolomics approach was carried out. First, 230 intracellular metabolites were identified and 14 of them remarkably influenced avermectin biosynthesis were discriminative biomarkers between non-SAM groups and SAM-treated groups by principal components analysis (PCA) and partial least squares (PLS). Based on further key metabolic pathway analyses, these biomarkers, such as glucose, oxaloacetic acid, fatty acids (in soybean oil), threonine, valine, and leucine, were identified as potentially beneficial precursors and added in medium. Compared with single-precursor feeding, the combined feeding of the precursors and SAM markedly increased the avermectin titer. The co-feeding approach not only directly verified our hypothesis on the mechanism of SAM by comparative metabolomics, but also provided a novel strategy to increase avermectin production.

Regge spectra of excited mesons, harmonic confinement, and QCD vacuum structure

NASA Astrophysics Data System (ADS)

Nedelko, Sergei N.; Voronin, Vladimir E.

2016-05-01

An approach to QCD vacuum as a medium describable in terms of a statistical ensemble of almost everywhere homogeneous Abelian (anti-)self-dual gluon fields is briefly reviewed. These fields play the role of the confining medium for color charged fields as well as underline the mechanism of realization of chiral S UL(Nf)×S UR(Nf) and UA(1 ) symmetries. Hadronization formalism based on this ensemble leads to manifestly defined quantum effective meson action. Strong, electromagnetic, and weak interactions of mesons are represented in the action in terms of nonlocal n -point interaction vertices given by the quark-gluon loops averaged over the background ensemble. New systematic results for the mass spectrum and decay constants of radially excited light, heavy-light mesons, and heavy quarkonia are presented. The interrelation between the present approach, models based on ideas of soft-wall anti-de Sitter/QCD, light-front holographic QCD, and the picture of harmonic confinement is outlined.

Noise impact of advanced high lift systems

NASA Technical Reports Server (NTRS)

Elmer, Kevin R.; Joshi, Mahendra C.

1995-01-01

The impact of advanced high lift systems on aircraft size, performance, direct operating cost and noise were evaluated for short-to-medium and medium-to-long range aircraft with high bypass ratio and very high bypass ratio engines. The benefit of advanced high lift systems in reducing noise was found to be less than 1 effective-perceived-noise decibel level (EPNdB) when the aircraft were sized to minimize takeoff gross weight. These aircraft did, however, have smaller wings and lower engine thrusts for the same mission than aircraft with conventional high lift systems. When the advanced high lift system was implemented without reducing wing size and simultaneously using lower flap angles that provide higher L/D at approach a cumulative noise reduction of as much as 4 EPNdB was obtained. Comparison of aircraft configurations that have similar approach speeds showed cumulative noise reduction of 2.6 EPNdB that is purely the result of incorporating advanced high lift system in the aircraft design.

Baryons and baryon resonances in nuclear matter

NASA Astrophysics Data System (ADS)

Lenske, Horst; Dhar, Madhumita; Gaitanos, Theodoros; Cao, Xu

2018-01-01

Theoretical approaches to the production of hyperons and baryon resonances in elementary hadronic reactions and heavy ion collisions are reviewed. The focus is on the production and interactions of baryons in the lowest SU(3) flavor octet and states from the next higher SU(3) flavor decuplet. Approaches using the SU(3) formalism for interactions of mesons and baryons and effective field theory for hyperons are discussed. An overview of application to free space and in-medium baryon-baryon interactions is given and the relation to a density functional theory is indicated. The intimate connection between baryon resonances and strangeness production is shown first for reactions on the nucleon. Pion-induced hypernuclear reactions are shown to proceed essentially through the excitation of intermediate nucleon resonances. Transport theory in conjunction with a statistical fragmentation model is an appropriate description of hypernuclear production in antiproton and heavy ion induced fragmentation reactions. The excitation of subnuclear degrees of freedom in peripheral heavy ion collisions at relativistic energies is reviewed. The status of in-medium resonance physics is discussed.

Extreme learning machine based optimal embedding location finder for image steganography

PubMed Central

Aljeroudi, Yazan

2017-01-01

In image steganography, determining the optimum location for embedding the secret message precisely with minimum distortion of the host medium remains a challenging issue. Yet, an effective approach for the selection of the best embedding location with least deformation is far from being achieved. To attain this goal, we propose a novel approach for image steganography with high-performance, where extreme learning machine (ELM) algorithm is modified to create a supervised mathematical model. This ELM is first trained on a part of an image or any host medium before being tested in the regression mode. This allowed us to choose the optimal location for embedding the message with best values of the predicted evaluation metrics. Contrast, homogeneity, and other texture features are used for training on a new metric. Furthermore, the developed ELM is exploited for counter over-fitting while training. The performance of the proposed steganography approach is evaluated by computing the correlation, structural similarity (SSIM) index, fusion matrices, and mean square error (MSE). The modified ELM is found to outperform the existing approaches in terms of imperceptibility. Excellent features of the experimental results demonstrate that the proposed steganographic approach is greatly proficient for preserving the visual information of an image. An improvement in the imperceptibility as much as 28% is achieved compared to the existing state of the art methods. PMID:28196080

Rational Design of Photonic Dust from Nanoporous Anodic Alumina Films: A Versatile Photonic Nanotool for Visual Sensing

PubMed Central

Chen, Yuting; Santos, Abel; Wang, Ye; Kumeria, Tushar; Ho, Daena; Li, Junsheng; Wang, Changhai; Losic, Dusan

2015-01-01

Herein, we present a systematic study on the development, optimisation and applicability of interferometrically coloured distributed Bragg reflectors based on nanoporous anodic alumina (NAA-DBRs) in the form of films and nanoporous microparticles as visual/colorimetric analytical tools. Firstly, we synthesise a complete palette of NAA-DBRs by galvanostatic pulse anodisation approach, in which the current density is altered in a periodic fashion in order to engineer the effective medium of the resulting photonic films in depth. NAA-DBR photonic films feature vivid colours that can be tuned across the UV-visible-NIR spectrum by structural engineering. Secondly, the effective medium of the resulting photonic films is assessed systematically by visual analysis and reflectometric interference spectroscopy (RIfS) in order to establish the most optimal nanoporous platforms to develop visual/colorimetric tools. Then, we demonstrate the applicability of NAA-DBR photonic films as a chemically selective sensing platform for visual detection of mercury(II) ions. Finally, we generate a new nanomaterial, so-called photonic dust, by breaking down NAA-DBRs films into nanoporous microparticles. The resulting microparticles (μP-NAA-DBRs) display vivid colours and are sensitive towards changes in their effective medium, opening new opportunities for developing advanced photonic nanotools for a broad range of applications. PMID:26245759

Rational Design of Photonic Dust from Nanoporous Anodic Alumina Films: A Versatile Photonic Nanotool for Visual Sensing

NASA Astrophysics Data System (ADS)

Chen, Yuting; Santos, Abel; Wang, Ye; Kumeria, Tushar; Ho, Daena; Li, Junsheng; Wang, Changhai; Losic, Dusan

2015-08-01

Herein, we present a systematic study on the development, optimisation and applicability of interferometrically coloured distributed Bragg reflectors based on nanoporous anodic alumina (NAA-DBRs) in the form of films and nanoporous microparticles as visual/colorimetric analytical tools. Firstly, we synthesise a complete palette of NAA-DBRs by galvanostatic pulse anodisation approach, in which the current density is altered in a periodic fashion in order to engineer the effective medium of the resulting photonic films in depth. NAA-DBR photonic films feature vivid colours that can be tuned across the UV-visible-NIR spectrum by structural engineering. Secondly, the effective medium of the resulting photonic films is assessed systematically by visual analysis and reflectometric interference spectroscopy (RIfS) in order to establish the most optimal nanoporous platforms to develop visual/colorimetric tools. Then, we demonstrate the applicability of NAA-DBR photonic films as a chemically selective sensing platform for visual detection of mercury(II) ions. Finally, we generate a new nanomaterial, so-called photonic dust, by breaking down NAA-DBRs films into nanoporous microparticles. The resulting microparticles (μP-NAA-DBRs) display vivid colours and are sensitive towards changes in their effective medium, opening new opportunities for developing advanced photonic nanotools for a broad range of applications.

Transport coefficients of a hot QCD medium and their relative significance in heavy-ion collisions

NASA Astrophysics Data System (ADS)

Mitra, Sukanya; Chandra, Vinod

2017-11-01

The main focus of this article is to obtain various transport coefficients for a hot QCD medium that is likely to be produced while colliding two heavy nuclei ultra-relativistically. The technical approach adopted here is the semiclassical transport theory. The away-from-equilibrium linearized transport equation has been set up by employing the Chapman-Enskog technique from the kinetic theory of a many-particle system with a collision term that includes the binary collisions of quarks/antiquarks and gluons. In order to include the effects of a strongly interacting, thermal medium, a quasi-particle description of a realistic hot QCD equation of state has been employed through the equilibrium modeling of the momentum distributions of gluons and quarks with nontrivial dispersion relations while extending the model for finite but small quark chemical potential. The effective coupling for strong interaction has been redefined following the charge renormalization under the scheme of the quasi-particle model. The consolidated effects on transport coefficients are seen to have a significant impact on their temperature dependence. Finally, the relative significances of momentum and heat transfer, as well as the charge diffusion processes in hot QCD, have been investigated by studying the ratios of the respective transport coefficients indicating different physical laws.

Realisation and advanced engineering of true optical rugate filters based on nanoporous anodic alumina by sinusoidal pulse anodisation

NASA Astrophysics Data System (ADS)

Santos, Abel; Yoo, Jeong Ha; Rohatgi, Charu Vashisth; Kumeria, Tushar; Wang, Ye; Losic, Dusan

2016-01-01

This study is the first realisation of true optical rugate filters (RFs) based on nanoporous anodic alumina (NAA) by sinusoidal waves. An innovative and rationally designed sinusoidal pulse anodisation (SPA) approach in galvanostatic mode is used with the aim of engineering the effective medium of NAA in a sinusoidal fashion. A precise control over the different anodisation parameters (i.e. anodisation period, anodisation amplitude, anodisation offset, number of pulses, anodisation temperature and pore widening time) makes it possible to engineer the characteristic reflection peaks and interferometric colours of NAA-RFs, which can be finely tuned across the UV-visible-NIR spectrum. The effect of the aforementioned anodisation parameters on the photonic properties of NAA-RFs (i.e. characteristic reflection peaks and interferometric colours) is systematically assessed in order to establish for the first time a comprehensive rationale towards NAA-RFs with fully controllable photonic properties. The experimental results are correlated with a theoretical model (Looyenga-Landau-Lifshitz - LLL), demonstrating that the effective medium of these photonic nanostructures can be precisely described by the effective medium approximation. NAA-RFs are also demonstrated as chemically selective photonic platforms combined with reflectometric interference spectroscopy (RIfS). The resulting optical sensing system is used to assess the reversible binding affinity between a model drug (i.e. indomethacin) and human serum albumin (HSA) in real-time. Our results demonstrate that this system can be used to determine the overall pharmacokinetic profile of drugs, which is a critical aspect to be considered for the implementation of efficient medical therapies.This study is the first realisation of true optical rugate filters (RFs) based on nanoporous anodic alumina (NAA) by sinusoidal waves. An innovative and rationally designed sinusoidal pulse anodisation (SPA) approach in galvanostatic mode is used with the aim of engineering the effective medium of NAA in a sinusoidal fashion. A precise control over the different anodisation parameters (i.e. anodisation period, anodisation amplitude, anodisation offset, number of pulses, anodisation temperature and pore widening time) makes it possible to engineer the characteristic reflection peaks and interferometric colours of NAA-RFs, which can be finely tuned across the UV-visible-NIR spectrum. The effect of the aforementioned anodisation parameters on the photonic properties of NAA-RFs (i.e. characteristic reflection peaks and interferometric colours) is systematically assessed in order to establish for the first time a comprehensive rationale towards NAA-RFs with fully controllable photonic properties. The experimental results are correlated with a theoretical model (Looyenga-Landau-Lifshitz - LLL), demonstrating that the effective medium of these photonic nanostructures can be precisely described by the effective medium approximation. NAA-RFs are also demonstrated as chemically selective photonic platforms combined with reflectometric interference spectroscopy (RIfS). The resulting optical sensing system is used to assess the reversible binding affinity between a model drug (i.e. indomethacin) and human serum albumin (HSA) in real-time. Our results demonstrate that this system can be used to determine the overall pharmacokinetic profile of drugs, which is a critical aspect to be considered for the implementation of efficient medical therapies. Electronic supplementary information (ESI) available: Table containing a comprehensive summary of the effect of the different anodisation parameters on the characteristic reflection peaks of NAA-RFs and further information on the relationship between glucose concentration and its refractive index and examples of ΔλPeak calculation for establishing the binding affinity between HSA and indomethacin molecules. See DOI: 10.1039/c5nr05462a

An Analytic Approach to Projectile Motion in a Linear Resisting Medium

ERIC Educational Resources Information Center

Stewart, Sean M.

2006-01-01

The time of flight, range and the angle which maximizes the range of a projectile in a linear resisting medium are expressed in analytic form in terms of the recently defined Lambert W function. From the closed-form solutions a number of results characteristic to the motion of the projectile in a linear resisting medium are analytically confirmed,…

Implementing English as a Medium of Instruction in a Ukrainian University: Challenges, Adjustments, and Opportunities

ERIC Educational Resources Information Center

Goodman, Bridget A.

2014-01-01

English as a medium of instruction (EMI) programs are an increasing phenomenon in European universities. This paper takes an ethnographic approach to understanding the impact of EMI on pedagogy in a private university in eastern Ukraine. Fieldwork was conducted over the 2010-2011 academic year in nine English-medium and three Russian-medium…

Analysis mathematical literacy skills in terms of the students’ metacognition on PISA-CPS model

NASA Astrophysics Data System (ADS)

Ovan; Waluya, S. B.; Nugroho, S. E.

2018-03-01

This research was aimed to know the effectiveness of PISA-CPS model and desceibe the mathematical literacy skills (KLM) in terms of the students’ metacognition. This study used Mixed Methods approaches with the concurrent embedded desaign. The technique of data analysis on quantitative research done analysis of lesson plan, prerequisite test, test hypotesis 1 and hypotesis test. While qualitative research done data reduction, data presentation, and drawing conclution and data verification. The subject of this study was the students of Grade Eight (VIII) of SMP Islam Sultan Agung 4 Semarang, Central Java. The writer analyzed the data with quantitative and qualitative approaches based on the metacognition of the students in low, medium and high groups. Subsequently, taken the mathematical literacy skills (KLM) from students’ metacognition in low, medium, and high . The results of the study showed that the PISA-CPS model was complete and the students’ mathematical literacy skills in terms of the students’ metacognition taught by the PISA-CPS model was higher than the expository learning. metacognitions’ students classified low hadmathematical literacy skills (KLM) less good, metacognitions’ students classified medium had mathematical literacy skills (KLM) good enough, metacognitions’ students classified high had mathematical literacy skills (KLM) very good. Based onresult analysis got conclusion that the PISA-CPS model was effective toward the students’ mathematical literacy skills (KLM). To increase the students’ mathematical literacy skills (KLM), the teachers need to provide reinforcements in the form of the exercises so that the student’s mathematical literacy was achieved at level 5 and level 6.

Interplay between proton-neutron pairing and deformation in self-conjugated medium mass nuclei

NASA Astrophysics Data System (ADS)

Gambacurta, Danilo; Lacroix, Denis

2016-05-01

We employ a model combining self-consistent mean-field and shell model techniques to study the competition between particle-like and proton-neutron pairing correlations in fp-shell even-even self-conjugate nuclei. Deformation effects are realistically and microscopically described. The resulting approach can give a precise description of pairing correlations and eventually treat the coexistence of different condensate formed of pairs with different total spin/ isospin. The standard BCS calculations are systematically compared with approaches including correlation effects beyond the independent quasi-particle picture. The competition between proton-neutron correlations in the isoscalar and isovector channels is also analyzed, as well as their dependence on the deformation properties.

Taking into account the impact of attrition on the assessment of response shift and true change: a multigroup structural equation modeling approach.

PubMed

Verdam, Mathilde G E; Oort, Frans J; van der Linden, Yvette M; Sprangers, Mirjam A G

2015-03-01

Missing data due to attrition present a challenge for the assessment and interpretation of change and response shift in HRQL outcomes. The objective was to handle such missingness and to assess response shift and 'true change' with the use of an attrition-based multigroup structural equation modeling (SEM) approach. Functional limitations and health impairments were measured in 1,157 cancer patients, who were treated with palliative radiotherapy for painful bone metastases, before [time (T) 0], every week after treatment (T1 through T12), and then monthly for up to 2 years (T13 through T24). To handle missing data due to attrition, the SEM procedure was extended to a multigroup approach, in which we distinguished three groups: short survival (3-5 measurements), medium survival (6-12 measurements), and long survival (>12 measurements). Attrition after third, sixth, and 13th measurement occasions was 11, 24, and 41 %, respectively. Results show that patterns of change in functional limitations and health impairments differ between patients with short, medium, or long survival. Moreover, three response-shift effects were detected: recalibration of 'pain' and 'sickness' and reprioritization of 'physical functioning.' If response-shift effects would not have been taken into account, functional limitations and health impairments would generally be underestimated across measurements. The multigroup SEM approach enables the analysis of data from patients with different patterns of missing data due to attrition. This approach does not only allow for detection of response shift and assessment of true change across measurements, but also allow for detection of differences in response shift and true change across groups of patients with different attrition rates.

Numerical simulation for peristalsis of Carreau-Yasuda nanofluid in curved channel with mixed convection and porous space

PubMed Central

Tanveer, Anum; Hayat, T.; Alsaedi, A.; Ahmad, B.

2017-01-01

Main theme of present investigation is to model and analyze the peristaltic activity of Carraeu-Yasuda nanofluid saturating porous space in a curved channel. Unlike the traditional approach, the porous medium effects are characterized by employing modified Darcy’s law for Carreau-Yasuda fluid. To our knowledge this is first attempt in this direction for Carreau-Yasuda fluid. Heat and mass transfer are further considered. Simultaneous effects of heat and mass transfer are examined in presence of mixed convection, viscous dissipation and thermal radiation. The compliant characteristics for channel walls are taken into account. The resulting complex mathematical system has been discussed for small Reynolds number and large wavelength concepts. Numerical approximation to solutions are thus plotted in graphs and the physical description is presented. It is concluded that larger porosity in a medium cause an enhancement in fluid velocity and reduction in concentration. PMID:28151968

Spectroscopy of 50Sc and ab initio calculations of B (M 3 ) strengths

NASA Astrophysics Data System (ADS)

Garnsworthy, A. B.; Bowry, M.; Olaizola, B.; Holt, J. D.; Stroberg, S. R.; Cruz, S.; Georges, S.; Hackman, G.; MacLean, A. D.; Measures, J.; Patel, H. P.; Pearson, C. J.; Svensson, C. E.

2017-10-01

The GRIFFIN spectrometer at TRIUMF-ISAC has been used to study excited states and transitions in 50Sc following the β decay of 50Ca. Branching ratios were determined from the measured γ -ray intensities, and angular correlations of γ rays have been used to firmly assign the spins of excited states. The presence of an isomeric state that decays by an M 3 transition with a B (M 3 ) strength of 13.6(7) W.u. has been confirmed. We compare the first ab initio calculations of B (M 3 ) strengths in light- and medium-mass nuclei from the valence-space in-medium similarity renormalization group approach, using consistently derived effective Hamiltonians and effective M 3 operator. The experimental data are well reproduced for isoscalar M 3 transitions when using bare g factors, but the strength of isovector M 3 transitions are found to be underestimated by an order of magnitude.

Excitation of turbulence by density waves

NASA Technical Reports Server (NTRS)

Tichen, C. M.

1985-01-01

A nonlinear system describes the microdynamical state of turbulence that is excited by density waves. It consists of an equation of propagation and a master equation. A group-scaling generates the scaled equations of many interacting groups of distribution functions. The two leading groups govern the transport processes of evolution and eddy diffusivity. The remaining sub-groups represent the relaxation for the approach of diffusivity to equilibrium. In strong turbulence, the sub-groups disperse themselves and the ensemble acts like a medium that offers an effective damping to close the hierarchy. The kinetic equation of turbulence is derived. It calculates the eddy viscosity and identifies the effective damping of the assumed medium self-consistently. It formulates the coupling mechanism for the intensification of the turbulent energy at the expense of the wave energy, and the transfer mechanism for the cascade. The spectra of velocity and density fluctuations find the power law k sup-2 and k sup-4, respectively.

Numerical simulation for peristalsis of Carreau-Yasuda nanofluid in curved channel with mixed convection and porous space.

PubMed

Tanveer, Anum; Hayat, T; Alsaedi, A; Ahmad, B

2017-01-01

Main theme of present investigation is to model and analyze the peristaltic activity of Carraeu-Yasuda nanofluid saturating porous space in a curved channel. Unlike the traditional approach, the porous medium effects are characterized by employing modified Darcy's law for Carreau-Yasuda fluid. To our knowledge this is first attempt in this direction for Carreau-Yasuda fluid. Heat and mass transfer are further considered. Simultaneous effects of heat and mass transfer are examined in presence of mixed convection, viscous dissipation and thermal radiation. The compliant characteristics for channel walls are taken into account. The resulting complex mathematical system has been discussed for small Reynolds number and large wavelength concepts. Numerical approximation to solutions are thus plotted in graphs and the physical description is presented. It is concluded that larger porosity in a medium cause an enhancement in fluid velocity and reduction in concentration.

Life support approaches for Mars missions

NASA Astrophysics Data System (ADS)

Drysdale, A. E.; Ewert, M. K.; Hanford, A. J.

Life support approaches for Mars missions are evaluated using an equivalent system mass (ESM) approach, in which all significant costs are converted into mass units. The best approach, as defined by the lowest mission ESM, depends on several mission parameters, notably duration, environment and consequent infrastructure costs, and crew size, as well as the characteristics of the technologies which are available. Generally, for the missions under consideration, physicochemical regeneration is most cost effective. However, bioregeneration is likely to be of use for producing salad crops for any mission, for producing staple crops for medium duration missions, and for most food, air and water regeneration for long missions (durations of a decade). Potential applications of in situ resource utilization need to be considered further.

Temporal behavior of a solute cloud in a fractal heterogeneous porous medium at different scales

NASA Astrophysics Data System (ADS)

Ross, Katharina; Attinger, Sabine

2010-05-01

Water pollution is still a very real problem and the need for efficient models for flow and solute transport in heterogeneous porous or fractured media is evident. In our study we focus on solute transport in heterogeneous fractured media. In heterogeneous fractured media the shape of the pores and fractures in the subsurface might be modeled as a fractal network or a heterogeneous structure with infinite correlation length. To derive explicit results for larger scale or effective transport parameters in such structures is the aim of this work. To describe flow and transport we investigate the temporal behavior of transport coefficients of solute movement through a spatially heterogeneous medium. It is necessary to distinguish between two fundamentally different quantities characterizing the solute dispersion: The effective dispersion coefficient Deff(t) represents the physical (observable) dispersion in one given realization of the medium. It is conceptually different from the mathematically simpler ensemble dispersion coefficient Dens(t) which characterizes the (abstract) dispersion with respect to the set of all possible realizations of the medium. In the framework of a stochastic approach DENTZ ET AL. (2000 I[2] & II[3]) derive explicit expressions for the temporal behavior of the center-of-mass velocity and the dispersion of the concentration distribution, using a second order perturbation expansion. In their model the authors assume a finite correlation length of the heterogeneities and use a GAUSSIAN correlation function. In a first step, we model the fractured medium as a heterogeneous porous medium with infinite correlation length and neglect single fractures. ZHAN & WHEATCRAFT (1996[4]) analyze the macrodispersivity tensor in fractal porous media using a non-integer exponent which consists of the HURST coefficient and the fractal dimension D. To avoid this non-integer exponent for numerical reasons we extend the study of DENTZ ET AL. (2000 I[2] & II[3]) and derive explicit expressions for the center-of-mass velocity and the longitudinal dispersion coefficient for isotropic and anisotropic media as well as for point-like (where the extent of the source distribution is small compared to the correlation lengths of the heterogeneities) and spatially extended injections. Our results clearly show that the difference between Deff and Dens persists for all times. In other words, ensemble mixing and effective mixing coefficients do not approach the same asymptotic limit. The center-of-mass fluctuations between different flow paths for a plume traveling through the medium never become irrelevant and ergodicity breaks down in such media. Our ongoing work concerns the investigation of the transversal dispersion coefficient and the extension of the upscaling method coarse graining[1] to heterogeneous fractal porous media with embedded single fractures. References [1]ATTINGER, S. (2003): Generalized coarse graining procedures for flow in porous media, Computational Geosciences, 7 (4), pp. 253-273. [2]DENTZ, M. / KINZELBACH, H. / ATTINGER, S. and W. KINZELBACH (2000): Temporal behavior of a solute cloud in a heterogeneous porous medium: 1. Point-like injection, Water Resources Research, 36 (12), pp. 3591-3604. [3]DENTZ, M. / KINZELBACH, H. / ATTINGER, S. and W. KINZELBACH (2000): Temporal behavior of a solute cloud in a heterogeneous porous medium: 2. Spatially extended injection, Water Resources Research, 36 (12), pp. 3605-3614. [4]ZHAN, H. and S. W. WHEATCRAFT (1996): Macrodispersivity tensor for nonreactive solute transport in isotropic and anisotropic fractal porous media: Analytical solutions, Water Resources Research, 32 (12), pp. 3461-3474.

13 C Flux Analysis Reveals that Rebalancing Medium Amino Acid Composition can Reduce Ammonia Production while Preserving Central Carbon Metabolism of CHO Cell Cultures.

PubMed

McAtee Pereira, Allison G; Walther, Jason L; Hollenbach, Myles; Young, Jamey D

2018-02-06

13 C metabolic flux analysis (MFA) provides a rigorous approach to quantify intracellular metabolism of industrial cell lines. In this study, 13 C MFA was used to characterize the metabolic response of Chinese hamster ovary (CHO) cells to a novel medium variant designed to reduce ammonia production. Ammonia inhibits growth and viability of CHO cell cultures, alters glycosylation of recombinant proteins, and enhances product degradation. Ammonia production was reduced by manipulating the amino acid composition of the culture medium; specifically, glutamine, glutamate, asparagine, aspartate, and serine levels were adjusted. Parallel 13 C flux analysis experiments determined that, while ammonia production decreased by roughly 40%, CHO cell metabolic phenotype, growth, viability, and monoclonal antibody (mAb) titer were not significantly altered by the changes in media composition. This study illustrates how 13 C flux analysis can be applied to assess the metabolic effects of media manipulations on mammalian cell cultures. The analysis revealed that adjusting the amino acid composition of CHO cell culture media can effectively reduce ammonia production while preserving fluxes throughout central carbon metabolism. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Improving forecasting accuracy of medium and long-term runoff using artificial neural network based on EEMD decomposition.

PubMed

Wang, Wen-chuan; Chau, Kwok-wing; Qiu, Lin; Chen, Yang-bo

2015-05-01

Hydrological time series forecasting is one of the most important applications in modern hydrology, especially for the effective reservoir management. In this research, an artificial neural network (ANN) model coupled with the ensemble empirical mode decomposition (EEMD) is presented for forecasting medium and long-term runoff time series. First, the original runoff time series is decomposed into a finite and often small number of intrinsic mode functions (IMFs) and a residual series using EEMD technique for attaining deeper insight into the data characteristics. Then all IMF components and residue are predicted, respectively, through appropriate ANN models. Finally, the forecasted results of the modeled IMFs and residual series are summed to formulate an ensemble forecast for the original annual runoff series. Two annual reservoir runoff time series from Biuliuhe and Mopanshan in China, are investigated using the developed model based on four performance evaluation measures (RMSE, MAPE, R and NSEC). The results obtained in this work indicate that EEMD can effectively enhance forecasting accuracy and the proposed EEMD-ANN model can attain significant improvement over ANN approach in medium and long-term runoff time series forecasting. Copyright © 2015 Elsevier Inc. All rights reserved.

Let's talk about sleep: a systematic review of psychological interventions to improve sleep in college students.

PubMed

Friedrich, Anja; Schlarb, Angelika A

2018-02-01

Sleep problems are a common occurrence in college students. Insomnia, nightmares and impaired sleep quality lead to several mental health issues, as well as impaired academic performance. Although different sleep programmes exist, a systematic overview comparing their effectiveness is still missing. This systematic review aims to provide an overview of psychological interventions to improve sleep in college students. Seven databases were searched from November to December 2016 (MEDLINE, EMBASE, PsycINFO, Cinahl, Cochrane Library, PubMed, OpenSigle). The search string included search terms from three different topics: sleep, intervention and college students. Outcome measures included subjective as well as objective measures and focused on sleep, sleep-related and mental health variables. Twenty-seven studies met the inclusion criteria. They were assigned to four intervention categories: (1) sleep hygiene, (2) cognitive-behavioural therapy (CBT), (3) relaxation, mindfulness and hypnotherapy and (4) other psychotherapeutic interventions. Fifteen studies were randomized controlled trials. While sleep hygiene interventions provided small to medium effects, the CBTs showed large effects. The variability of the effect sizes was especially large in the relaxation category, ranging from very small to very large effect sizes. Other psychotherapeutic interventions showed medium effects. CBT approaches provided the best effects for the improvement of different sleep variables in college students. Five studies included insomnia patients. The other three intervention categories also showed promising results with overall medium effects. In the future, CBT should be combined with relaxation techniques, mindfulness and hypnotherapy. Furthermore, the interventions should broaden their target group and include more sleep disorders. © 2017 European Sleep Research Society.

Estimating regression to the mean and true effects of an intervention in a four-wave panel study.

PubMed

Gmel, Gerhard; Wicki, Matthias; Rehm, Jürgen; Heeb, Jean-Luc

2008-01-01

First, to analyse whether a taxation-related decrease in spirit prices had a similar effect on spirit consumption for low-, medium- and high-level drinkers. Secondly, as the relationship between baseline values and post-intervention changes is confounded with regression to the mean (RTM) effects, to apply different approaches for estimating the RTM effect and true change. Consumption of spirits and total alcohol consumption were analysed in a four-wave panel study (one pre-intervention and three post-intervention measurements) of 889 alcohol consumers sampled from the general population of Switzerland. Two correlational methods, one method quantitatively estimating the RTM effect and one growth curve approach based on hierarchical linear models (HLM), were used to estimate RTM effects among low-, medium- and high-level drinkers. Adjusted for RTM effects, high-level drinkers increased consumption more than lighter drinkers in the short term, but this was not a persisting effect. Changes in taxation affected mainly light and moderate drinkers in the long term. All methods concurred that RTM effects were present to a considerable degree, and methods quantifying the RTM effect or adjusting for it yielded similar estimates. Intervention studies have to consider RTM effects both in the study design and in the evaluation methods. Observed changes can be adjusted for RTM effects and true change can be estimated. The recommended method, particularly if the aim is to estimate change not only for the sample as a whole, but for groups of drinkers with different baseline consumption levels, is growth curve modelling. If reliability of measurement instruments cannot be increased, the incorporation of more than one pre-intervention measurement point may be a valuable adjustment of the study design.

A homogenization approach for the effective drained viscoelastic properties of 2D porous media and an application for cortical bone.

PubMed

Nguyen, Sy-Tuan; Vu, Mai-Ba; Vu, Minh-Ngoc; To, Quy-Dong

2018-02-01

Closed-form solutions for the effective rheological properties of a 2D viscoelastic drained porous medium made of a Generalized Maxwell viscoelastic matrix and pore inclusions are developed and applied for cortical bone. The in-plane (transverse) effective viscoelastic bulk and shear moduli of the Generalized Maxwell rheology of the homogenized medium are expressed as functions of the porosity and the viscoelastic properties of the solid phase. When deriving these functions, the classical inverse Laplace-Carson transformation technique is avoided, due to its complexity, by considering the short and long term approximations. The approximated results are validated against exact solutions obtained from the inverse Laplace-Carson transform for a simple configuration when the later is available. An application for cortical bone with assumption of circular pore in the transverse plane shows that the proposed approximation fit very well with experimental data. Copyright © 2017 Elsevier Ltd. All rights reserved.

The effect of multiplicity of stellar encounters and the diffusion coefficients in a locally homogeneous three-dimensional stellar medium: Removing the classical divergence

NASA Astrophysics Data System (ADS)

Rastorguev, A. S.; Utkin, N. D.; Chumak, O. V.

2017-08-01

Agekyan's λ-factor that allows for the effect of multiplicity of stellar encounters with large impact parameters has been used for the first time to directly calculate the diffusion coefficients in the phase space of a stellar system. Simple estimates show that the cumulative effect, i.e., the total contribution of distant encounters to the change in the velocity of a test star, given the multiplicity of stellar encounters, is finite, and the logarithmic divergence inherent in the classical description of diffusion is removed, as was shown previously byKandrup using a different, more complex approach. In this case, the expressions for the diffusion coefficients, as in the classical description, contain the logarithm of the ratio of two independent quantities: the mean interparticle distance and the impact parameter of a close encounter. However, the physical meaning of this logarithmic factor changes radically: it reflects not the divergence but the presence of two characteristic length scales inherent in the stellar medium.

Teaching Medium-Sized ERP Systems - A Problem-Based Learning Approach

NASA Astrophysics Data System (ADS)

Winkelmann, Axel; Matzner, Martin

In order to increase the diversity in IS education, we discuss an approach for teaching medium-sized ERP systems in master courses. Many of today's IS curricula are biased toward large ERP packages. Nevertheless, these ERP systems are only a part of the ERP market. Hence, this chapter describes a course outline for a course on medium-sized ERP systems. Students had to study, analyze, and compare five different ERP systems during a semester. The chapter introduces a procedure model and scenario for setting up similar courses at other universities. Furthermore, it describes some of the students' outcomes and evaluates the contribution of the course with regard to a practical but also academic IS education.

Effect of motion cues during complex curved approach and landing tasks: A piloted simulation study

NASA Technical Reports Server (NTRS)

Scanlon, Charles H.

1987-01-01

A piloted simulation study was conducted to examine the effect of motion cues using a high fidelity simulation of commercial aircraft during the performance of complex approach and landing tasks in the Microwave Landing System (MLS) signal environment. The data from these tests indicate that in a high complexity MLS approach task with moderate turbulence and wind, the pilot uses motion cues to improve path tracking performance. No significant differences in tracking accuracy were noted for the low and medium complexity tasks, regardless of the presence of motion cues. Higher control input rates were measured for all tasks when motion was used. Pilot eye scan, as measured by instrument dwell time, was faster when motion cues were used regardless of the complexity of the approach tasks. Pilot comments indicated a preference for motion. With motion cues, pilots appeared to work harder in all levels of task complexity and to improve tracking performance in the most complex approach task.

Reinvestigation of Brevibacterium sp. Strain KY-4313 as a Source of Canthaxanthin

PubMed Central

Nelis, H. J.; De Leenheer, A. P.

1989-01-01

The hydrocarbon-utilizing Brevibacterium sp. strain KY-4313 was reevaluated for its potential to produce canthaxanthin, a carotenoid pigment of strong commercial interest. Three approaches were used to optimize the canthaxanthin yield from this organism, i.e., the preparation of mutants, the addition of supposedly carotenogenic chemicals to the growth medium, and growth promotion. Following treatment of the parent strain with N-nitrosomethylurea, a presumed mutant was isolated which showed a 32% increase in cellular canthaxanthin content. No effective carotenogenic chemicals were found in connection with hydrocarbon fermentations, in which mainly growth promotion through periodic medium renewal proved conducive to enhanced pigment production. Carotenogenesis could be stimulated in brain heart infusion broth by adding alcohols or retinol. Improved growth in this medium was generally not associated with higher canthaxanthin yields. Both superior growth and pigment levels were obtained in a newly designed medium based on fumaric acid-molasses. The maximum yields of canthaxanthin in shake flasks were (in milligrams per liter) 4.2 (brain heart infusion broth plus propanol-zinc sulfate), 3.6 (hydrocarbon medium), and 9.3 (fumaric acid-molasses), which represent a significant improvement over the originally reported optimal result (1 mg/liter). The corresponding yields of echinenone, the direct precursor of canthaxanthin, were 1.2, 1.6, and 2.3 mg/liter, respectively. Two-liter hydrocarbon batch fermentations involving medium renewal maximally produced 7.2 mg of canthaxanthin and 3.7 mg of echinenone per liter. PMID:16348027

Continued development of a semianalytical solution for two-phase fluid and heat flow in a porous medium

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

Doughty, C.; Pruess, K.

1991-06-01

Over the past few years the authors have developed a semianalytical solution for transient two-phase water, air, and heat flow in a porous medium surrounding a constant-strength linear heat source, using a similarity variable {eta} = r/{radical}t. Although the similarity transformation approach requires a simplified geometry, all the complex physical mechanisms involved in coupled two-phase fluid and heat flow can be taken into account in a rigorous way, so that the solution may be applied to a variety of problems of current interest. The work was motivated by adverse to predict the thermohydrological response to the proposed geologic repository formore » heat-generating high-level nuclear wastes at Yucca Mountain, Nevada, in a partially saturated, highly fractured volcanic formation. The paper describes thermal and hydrologic conditions near the heat source; new features of the model; vapor pressure lowering; and the effective-continuum representation of a fractured/porous medium.« less

Homogenization via the strong-permittivity-fluctuation theory with nonzero depolarization volume

NASA Astrophysics Data System (ADS)

Mackay, Tom G.

2004-08-01

The depolarization dyadic provides the scattering response of a single inclusion particle embedded within a homogenous background medium. These dyadics play a central role in formalisms used to estimate the effective constitutive parameters of homogenized composite mediums (HCMs). Conventionally, the inclusion particle is taken to be vanishingly small; this allows the pointwise singularity of the dyadic Green function associated with the background medium to be employed as the depolarization dyadic. A more accurate approach is pursued in this communication by taking into account the nonzero spatial extent of inclusion particles. Depolarization dyadics corresponding to inclusion particles of nonzero volume are incorporated within the strong-permittivity-fluctuation theory (SPFT). The linear dimensions of inclusion particles are assumed to be small relative to the electromagnetic wavelength(s) and the SPFT correlation length. The influence of the size of inclusion particles upon SPFT estimates of the HCM constitutive parameters is investigated for anisotropic dielectric HCMs.In particular, the interplay between correlation length and inclusion size is explored.

Simulations on false gain in recombination-pumped soft-X-ray lasers

NASA Astrophysics Data System (ADS)

Ozaki, T.; Kuroda, H.

1997-10-01

Numerical investigations are performed on false gain due to axial plasma expansion, which is expected to be important in initial proof-of-principle studies of recombination-pumped soft-X-ray lasers with extended capabilities. Modelling calculations of experiments with slab boron nitride targets reveal large false gain coefficients approaching 20 cm-1 in the case of plasmas with short active medium lengths. The false gain in the case of fiber targets is found to be of equal magnitude to that for slabs in the case of plasmas with less than 0.1 cm active medium lengths. Calculations for slab targets predict that adopting a tolerance of ǃ cm-1 for gain will severely restrict the time and the active medium length of the plasma that can be used for error-free observations, while those for fiber targets are found to be considerably relaxed. The effects of false gain in the 54.2 + Na Balmer ! laser is also investigated, again revealing the importance of this phenomena under optimum gain conditions.

Quantitative Modeling of Coupled Piezo-Elastodynamic Behavior of Piezoelectric Actuators Bonded to an Elastic Medium for Structural Health Monitoring: A Review

PubMed Central

Huang, Guoliang; Song, Fei; Wang, Xiaodong

2010-01-01

Elastic waves, especially guided waves, generated by a piezoelectric actuator/sensor network, have shown great potential for on-line health monitoring of advanced aerospace, nuclear, and automotive structures in recent decades. Piezoelectric materials can function as both actuators and sensors in these applications due to wide bandwidth, quick response and low costs. One of the most fundamental issues surrounding the effective use of piezoelectric actuators is the quantitative evaluation of the resulting elastic wave propagation by considering the coupled piezo-elastodynamic behavior between the actuator and the host medium. Accurate characterization of the local interfacial stress distribution between the actuator and the host medium is the key issue for the problem. This paper presents a review of the development of analytical, numerical and hybrid approaches for modeling of the coupled piezo-elastodynamic behavior. The resulting elastic wave propagation for structural health monitoring is also summarized. PMID:22319319

Oxidation of L-phenylalanine by diperiodatoargentate(III) in aqueous alkaline medium. A Mechanistic approach

NASA Astrophysics Data System (ADS)

Lamani, S. D.; Veeresh, T. M.; Nandibewoor, S. T.

2009-12-01

The kinetics of oxidation of L-phenylalanine (L-Phe) by diperiodatoargentate(III) (DPA) in alkaline medium at a constant ionic strength of 0.25 mol/dm-3 has been studied spectrophotometrically. The reaction between DPA and L-phenylalanine in alkaline medium exhibits 1: 1 stoichiometry (L-phenylalanine: DPA). The reaction shows first order in [DPA] and has less than unit order dependence each in both [L-Phe] and [Alkali] and retarding effect of [IO{4/-}] under the reaction conditions. The active species of DPA is understood to be as monoperiodatoargentate(III) (MPA). The reaction is shown to proceed via a MPA-L-Phe complex, which decomposes in a rate-determining step to give intermediates followed by a fast step to give the products. The products were identified by spot and spectroscopic studies. The reaction constants involved in the different steps of the mechanisms were calculated. The activation parameters with respect to slow step of the mechanism were computed and discussed. The thermodynamic quantities were also determined for the reaction.

BioComponent Robots

DTIC Science & Technology

2014-02-13

sterile water. Culture medium was prepared with 70% Leibovitz’s L15 medium, 18% Grace’s Insect Medium, 12% fetal bovine serum (FBS), 3.4 mg/mL yeast...SECURITY CLASSIFICATION OF: The project goal was to exploit insect cell culture and tissue engineering approaches to generate biological actuators...utilizing the unique hardiness and longevity of insect cell sources for device applications for robotics. In contrast to mammalian cells and tissues

Effect of hydrotalcite-like compounds on the aqueous solubility of some poorly water-soluble drugs.

PubMed

Ambrogi, Valeria; Fardella, Giuseppe; Grandolini, Giuliano; Nocchetti, Morena; Perioli, Luana

2003-07-01

A new approach of improving drug dissolution properties is described. This method exploits the property of a carrier owing to the hydrotalcite-type anionic clays (HTlc). HTlc is an inorganic layered solid that lodges anionic compounds among its layers. As HTlc dissolves at acidic pH values (pH < 4), the anions intercalated among the layers are promptly released in the medium. In this article some nonsteroidal antiinflammatory drugs were chosen as models of poorly water-soluble drugs. They were intercalated in HTlc and solubility measurements in acidic medium were performed. A remarkable improvement of drug solubility was observed especially in the case of indomethacin. Copyright 2003 Wiley-Liss, Inc. and the American Pharmacists Association

Aiding flow Thermo-Solutal Convection in Porous Cavity: ANN approach

NASA Astrophysics Data System (ADS)

Jafer Kazi1, Mohammed; Ameer Ahamad, N.; Yunus Khan, T. M.

2017-08-01

The transfer of thermal energy along with the diffusion of mass is common phenomenon that occurs in nature. The thermos-solutal convection in porous medium arises due to combined effect of diffusion of heat as well as mass inside the domain. The density variation of fluid due to absorbed heat at one end of porous cavity leads to fluid movement which in turn initiates the heat transfer. The mass diffusion inside the porous regime occurs due to concentration difference between two ends of cavity. Generally this phenomenon is studied with the help of numerical methods but current work emphasis the successful usage of artificial neural network in predicting the thermos-solutal convection of aiding flow in porous medium.

Three-dimensional localization and optical imaging of objects in turbid media with independent component analysis.

PubMed

Xu, M; Alrubaiee, M; Gayen, S K; Alfano, R R

2005-04-01

A new approach for optical imaging and localization of objects in turbid media that makes use of the independent component analysis (ICA) from information theory is demonstrated. Experimental arrangement realizes a multisource illumination of a turbid medium with embedded objects and a multidetector acquisition of transmitted light on the medium boundary. The resulting spatial diversity and multiple angular observations provide robust data for three-dimensional localization and characterization of absorbing and scattering inhomogeneities embedded in a turbid medium. ICA of the perturbations in the spatial intensity distribution on the medium boundary sorts out the embedded objects, and their locations are obtained from Green's function analysis based on any appropriate light propagation model. Imaging experiments were carried out on two highly scattering samples of thickness approximately 50 times the transport mean-free path of the respective medium. One turbid medium had two embedded absorptive objects, and the other had four scattering objects. An independent component separation of the signal, in conjunction with diffusive photon migration theory, was used to locate the embedded inhomogeneities. In both cases, improved lateral and axial localizations of the objects over the result obtained by use of common photon migration reconstruction algorithms were achieved. The approach is applicable to different medium geometries, can be used with any suitable photon propagation model, and is amenable to near-real-time imaging applications.

Energy-density field approach for low- and medium-frequency vibroacoustic analysis of complex structures using a statistical computational model

NASA Astrophysics Data System (ADS)

Kassem, M.; Soize, C.; Gagliardini, L.

2009-06-01

In this paper, an energy-density field approach applied to the vibroacoustic analysis of complex industrial structures in the low- and medium-frequency ranges is presented. This approach uses a statistical computational model. The analyzed system consists of an automotive vehicle structure coupled with its internal acoustic cavity. The objective of this paper is to make use of the statistical properties of the frequency response functions of the vibroacoustic system observed from previous experimental and numerical work. The frequency response functions are expressed in terms of a dimensionless matrix which is estimated using the proposed energy approach. Using this dimensionless matrix, a simplified vibroacoustic model is proposed.

Combined phosphorescence-holographic approach for singlet oxygen detection in biological media

NASA Astrophysics Data System (ADS)

Semenova, I. V.; Belashov, A. V.; Beltukova, D. M.; Petrov, N. V.; Vasyutinskii, O. S.

2015-06-01

The paper presents a novel combined approach aimed to detect and monitor singlet oxygen molecules in biological specimens by means of the simultaneous recording and monitoring of their deactivation dynamics in the two complementary channels: radiative and nonradiative. The approach involves both the direct registration of phosphorescence at the wavelength of about 1270 nm caused by radiative relaxation of excited singlet oxygen molecules and holographic recording of thermal disturbances in the medium produced by their nonradiative relaxation. The data provides a complete set of information on singlet oxygen location and dynamics in the medium. The approach was validated in the case study of photosensitized generation of singlet oxygen in onion cell structures.

A high-throughput media design approach for high performance mammalian fed-batch cultures

PubMed Central

Rouiller, Yolande; Périlleux, Arnaud; Collet, Natacha; Jordan, Martin; Stettler, Matthieu; Broly, Hervé

2013-01-01

An innovative high-throughput medium development method based on media blending was successfully used to improve the performance of a Chinese hamster ovary fed-batch medium in shaking 96-deepwell plates. Starting from a proprietary chemically-defined medium, 16 formulations testing 43 of 47 components at 3 different levels were designed. Media blending was performed following a custom-made mixture design of experiments considering binary blends, resulting in 376 different blends that were tested during both cell expansion and fed-batch production phases in one single experiment. Three approaches were chosen to provide the best output of the large amount of data obtained. A simple ranking of conditions was first used as a quick approach to select new formulations with promising features. Then, prediction of the best mixes was done to maximize both growth and titer using the Design Expert software. Finally, a multivariate analysis enabled identification of individual potential critical components for further optimization. Applying this high-throughput method on a fed-batch, rather than on a simple batch, process opens new perspectives for medium and feed development that enables identification of an optimized process in a short time frame. PMID:23563583

Linking human capital and enterprise sustainability in Indonesian medium-sized food manufacturing enterprises: the role of informal knowledge sharing practice

NASA Astrophysics Data System (ADS)

Sunardi, O.

2017-12-01

Medium-sized food manufacturing enterprises in Indonesia are significant in a number of contexts, in terms of their part to the national production (GDP) and their establishment to the employment. In term of their role to national production, manufacturing sector contributes the highest GDP by 85%. In this sector, food manufacturing subsector contributes the highest GDP. Nevertheless, they faced the same common problems: quality of human capital and sustainability issues. Previous government supplementary programs have been established to expand the human capital capability amongst medium enterprises. Adequate amount of fund has been apportioned to develop human capital, though, the medium enterprises sustainability is still in question. This study proposes and examines the human capital role from informal knowledge sharing perspective. By conducting qualitative approach through interviews to four informants in Indonesian medium-sized food manufacturing enterprises, a set of hypotheses is derived from this study for future quantitative study. This study indicates that human capital traits (diverse education background, employee skills, and employee experience) could leverage the practice of informal knowledge sharing. Constructs such as mutual trust and reciprocal intention could play as mediating variables, and cultural interpretation perspective could act as moderating factor to informal knowledge sharing effectiveness. In final, informal knowledge sharing is indicated to play as moderating variable for human capital policy and practice to support enterprise sustainability.

Rapid screening of serum-free media for the growth of adherent Vero cells by using a small-scale and non-invasive tool.

PubMed

Petiot, Emma; Fournier, Frantz; Gény, Cécile; Pinton, Hervé; Marc, Annie

2010-03-01

The paper proposes a rapid screening method for a first step improvement of an animal component-free medium dedicated to the growth of the anchorage-dependent Vero cell line. A new, rapid, and non-invasive technique is presented to specifically monitor cultures of adherent cells in 96-well plates. The operating conditions of an image analyzer are adapted to take into account the decrease of cell size when the attached cell density increases. An experimental design is carried out to assess the influence of ten component groups in the original medium. Two groups including protein extracts, growth factor, insulin, glucose, and pyruvate show significant positive effects. The groups with vitamins and molecules related to nitrogenous bases display a less pronounced influence. The mixture of amino acids, B(1) vitamin, magnesium sulfate, and sodium phosphate as well as the couple sodium citrate and ferric chloride lead to a downward trend. The screening results are proved to be scalable in stirred cultures with cells on microcarriers. An improved serum-free medium, with some component groups being removed or added, can be rapidly formulated to reach respectively similar or 1.6 times higher cell density than in the original medium. The results from this global approach could be helpful to further focus experiments on identified medium components.

Enhanced production of optically pure d (-) lactic acid from nutritionally rich Borassus flabellifer sugar and whey protein hydrolysate based-fermentation medium.

PubMed

Reddy Tadi, Subbi Rami; E V R, Arun; Limaye, Anil Mukund; Sivaprakasam, Senthilkumar

2017-03-01

The aim of this study is to optimize the production of optically pure d (-) lactic acid (DLA) employing a cost-effective production medium. Based on the designed biomass approach, Sporolactobacillus inulinus NBRC 13595 was found to exhibit high DLA titer (19.0 g L -1 ) and optical purity (99.6%). A cost-effective medium was constituted using Palmyra palm jaggery (PJ) from Borassus flabellifer and whey protein hydrolysate (WPH) as carbon and nitrogen sources, respectively. Plackett-Burman design indicated that PJ, WPH, and MnSO 4 as significant variables influence DLA production. A rotatable central composite design and response surface methodology were used to optimize the PJ and WPH concentrations. A maximum DLA titer (170.14 g L -1 ) was predicted for 222.24 g L -1 of PJ and 11.99 g L -1 of WPH, respectively. Fermentation experimental results exhibited a maximum DLA titer (189.0 ± 8.53 g L -1 ) and productivity (5.25 ± 0.24 g L -1 H -1 ), which is the highest ever reported for DLA production from a renewable feedstock in the batch process. The present investigation substantiates that the potential application of economically viable raw feedstocks (PJ and WPH) for enhanced DLA production, which is attributed to 2.5-fold reduction in DLA production cost compared with conventional medium. © 2015 International Union of Biochemistry and Molecular Biology, Inc.

Risk determinants of small and medium-sized manufacturing enterprises (SMEs) - an exploratory study in New Zealand

NASA Astrophysics Data System (ADS)

Islam, Ariful; Tedford, Des

2012-08-01

The smooth running of small and medium-sized manufacturing enterprises (SMEs) presents a significant challenge irrespective of the technological and human resources they may have at their disposal. SMEs continuously encounter daily internal and external undesirable events and unwanted setbacks to their operations that detract from their business performance. These are referred to as `disturbances' in our research study. Among the disturbances, some are likely to create risks to the enterprises in terms of loss of production, manufacturing capability, human resource, market share, and, of course, economic losses. These are finally referred to as `risk determinant' on the basis of their correlation with some risk indicators, which are linked to operational, occupational, and economic risks. To deal with these risk determinants effectively, SMEs need a systematic method of approach to identify and treat their potential effects along with an appropriate set of tools. However, initially, a strategic approach is required to identify typical risk determinants and their linkage with potential business risks. In this connection, we conducted this study to explore the answer to the research question: what are the typical risk determinants encountered by SMEs? We carried out an empirical investigation with a multi-method research approach (a combination of a questionnaire-based mail survey involving 212 SMEs and five in-depth case studies) in New Zealand. This paper presents a set of typical internal and external risk determinants, which need special attention to be dealt with to minimize operational risks of an SME.

Rapid in vitro propagation, conservation and analysis of genetic stability of Viola pilosa.

PubMed

Soni, Madhvi; Kaur, Rajinder

2014-01-01

A protocol for in vitro propagation was developed for Viola pilosa, a plant of immense medicinal value. To start with in vitro propagation, the sterilized explants (buds) were cultured on MS basal medium supplemented with various concentrations of growth regulators. One of the medium compositions MS basal + 0.5 mg/l BA + 0.5 mg/l TDZ + 0.5 mg/l GA3 gave best results for in vitro shoot bud establishment. Although the problem of shoot vitrification occurred on this medium but this was overcome by transferring the vitrified shoots on MS medium supplemented with 1 mg/l BA and 0.25 mg/l Kn. The same medium was found to be the best medium for further in vitro shoot multiplication. 100 % root induction from in vitro grown shoots was obtained on half strength MS medium supplemented with 1 mg/l IBA. In vitro formed plantlets were hardened and transferred to soil with 83 % survival. Additionally, conservation of in vitro multiplying shoots was also attempted using two different approaches namely slowing down the growth at low temperature and cryopreservation following vitrification. At low temperature retrieval rate was better at 10 °C than at 4 °C after conservation of in vitro multiplying shoots. In cryopreservation-vitrification studies, the vitrified shoot buds gave maximum retrieval of 41.66 % when they were precooled at 4 °C, while only 16.66 % vitrified shoots were retrieved from those precooled at 10 °C. Genetic stability of the in vitro grown plants was analysed by RAPD and ISSR markers which indicated no somaclonal variation among in vitro grown plants demonstrating the feasibility of using the protocol without any adverse genetical effects.

Associations between Culturally Relevant Recruitment Strategies and Participant Interest, Enrollment and Generalizability in a Weight-loss Intervention for African American Families.

PubMed

Huffman, Lauren E; Wilson, Dawn K; Kitzman-Ulrich, Heather; Lyerly, Jordan E; Gause, Haylee M; Resnicow, Ken

2016-07-21

Culturally relevant recruitment strategies may be an important approach for recruiting ethnic minorities for interventions. Previous research has examined associations between recruitment strategies and enrollment of African Americans (AA), but has not explored more deeply the role of incorporating sociocultural values into recruitment strategies. Our current study explores whether sociocultural recruitment mediums were associated with demographics, interest and enrollment in a weight-loss intervention. Sociocultural mediums included community partnerships, culturally relevant ads, sociocultural events, or word-of-mouth. Non-sociocultural mediums included community/school events that did not specifically target AAs. Analyses examined whether demographics of enrolled families differed by recruitment strategy and if recruitment strategy predicted scheduling a baseline visit, enrolling in a run-in phase, and enrolling in the intervention program. Families recruited from culturally relevant ads, sociocultural events, or word-of-mouth were 1.96 times more likely to schedule a baseline visit (OR=1.96, 95% CI=1.05, 3.68) than families recruited from non-sociocultural mediums. No differences were found for sociocultural mediums on enrolling in the run-in phase or the intervention. However, among enrolled families, those recruited from sociocultural mediums were less likely to be employed (X(2) [1, N=142] =5.53, P<.05) and more likely to have lower income (X(2) [1, N=142] =13.57, P<.05). Sociocultural mediums were associated with scheduling a baseline visit, but not enrollment. They were, however, effective in recruiting a more generalizable sample among enrolled participants based on demographic characteristics. Integrating sociocultural values into recruitment methods may be a valuable strategy for increasing interest in participation among underrepresented AA families.

Effective electromagnetic properties of microheterogeneous materials with surface phenomena

NASA Astrophysics Data System (ADS)

Levin, Valery; Markov, Mikhail; Mousatov, Aleksandr; Kazatchenko, Elena; Pervago, Evgeny

2017-10-01

In this paper, we present an approach to calculate the complex dielectric permittivity of a micro-heterogeneous medium composed of non-conductive solid inclusions embedded into the conductive liquid continuous host. To take into account the surface effects, we approximate the inclusion by a layered ellipsoid consisting of a dielectric core and an infinitesimally thin outer shell corresponding to an electrical double layer (EDL). To predict the effective complex dielectric permittivity of materials with a high concentration of inclusions, we have modified the Effective Field Method (EFM) for the layered ellipsoidal particles with complex electrical properties. We present the results of complex permittivity calculations for the composites with randomly and parallel oriented ellipsoidal inclusions. To analyze the influence of surface polarization, we have accomplished modeling in a wide frequency range for different existing physic-chemical models of double electrical layer. The results obtained show that the tensor of effective complex permittivity of a micro-heterogeneous medium with surface effects has complicate dependences on the component electrical properties, spatial material texture, and the inclusion shape (ellipsoid aspect ratio) and size. The dispersion of dielectric permittivity corresponds to the frequency dependence for individual inclusion of given size, and does not depend on the inclusion concentration.

Life support approaches for Mars missions

NASA Technical Reports Server (NTRS)

Drysdale, A. E.; Ewert, M. K.; Hanford, A. J.

2003-01-01

Life support approaches for Mars missions are evaluated using an equivalent system mass (ESM) approach, in which all significant costs are converted into mass units. The best approach, as defined by the lowest mission ESM, depends on several mission parameters, notably duration, environment and consequent infrastructure costs, and crew size, as well as the characteristics of the technologies which are available. Generally, for the missions under consideration, physicochemical regeneration is most cost effective. However, bioregeneration is likely to be of use for producing salad crops for any mission, for producing staple crops for medium duration missions, and for most food, air and water regeneration for long missions (durations of a decade). Potential applications of in situ resource utilization need to be considered further. c2002 Published by Elsevier Science Ltd on behalf of COSPAR.

Life support approaches for Mars missions.

PubMed

Drysdale, A E; Ewert, M K; Hanford, A J

2003-01-01

Life support approaches for Mars missions are evaluated using an equivalent system mass (ESM) approach, in which all significant costs are converted into mass units. The best approach, as defined by the lowest mission ESM, depends on several mission parameters, notably duration, environment and consequent infrastructure costs, and crew size, as well as the characteristics of the technologies which are available. Generally, for the missions under consideration, physicochemical regeneration is most cost effective. However, bioregeneration is likely to be of use for producing salad crops for any mission, for producing staple crops for medium duration missions, and for most food, air and water regeneration for long missions (durations of a decade). Potential applications of in situ resource utilization need to be considered further. c2002 Published by Elsevier Science Ltd on behalf of COSPAR.

Mesenchymal Stromal Cell Secreted Sphingosine 1-Phosphate (S1P) Exerts a Stimulatory Effect on Skeletal Myoblast Proliferation

PubMed Central

Tani, Alessia; Anderloni, Giulia; Pierucci, Federica; Matteini, Francesca; Chellini, Flaminia; Zecchi Orlandini, Sandra; Meacci, Elisabetta

2014-01-01

Bone-marrow-derived mesenchymal stromal cells (MSCs) have the potential to significantly contribute to skeletal muscle healing through the secretion of paracrine factors that support proliferation and enhance participation of the endogenous muscle stem cells in the process of repair/regeneration. However, MSC-derived trophic molecules have been poorly characterized. The aim of this study was to investigate paracrine signaling effects of MSCs on skeletal myoblasts. It was found, using a biochemical and morphological approach that sphingosine 1-phosphate (S1P), a natural bioactive lipid exerting a broad range of muscle cell responses, is secreted by MSCs and represents an important factor by which these cells exert their stimulatory effects on C2C12 myoblast and satellite cell proliferation. Indeed, exposure to conditioned medium obtained from MSCs cultured in the presence of the selective sphingosine kinase inhibitor (iSK), blocked increased cell proliferation caused by the conditioned medium from untreated MSCs, and the addition of exogenous S1P in the conditioned medium from MSCs pre-treated with iSK further increased myoblast proliferation. Finally, we also demonstrated that the myoblast response to MSC-secreted vascular endothelial growth factor (VEGF) involves the release of S1P from C2C12 cells. Our data may have important implications in the optimization of cell-based strategies to promote skeletal muscle regeneration. PMID:25264785

General quantitative analysis of stress partitioning and boundary conditions in undrained biphasic porous media via a purely macroscopic and purely variational approach

NASA Astrophysics Data System (ADS)

Serpieri, Roberto; Travascio, Francesco

2016-03-01

In poroelasticity, the effective stress law relates the external stress applied to the medium to the macroscopic strain of the solid phase and the interstitial pressure of the fluid saturating the mixture. Such relationship has been formerly introduced by Terzaghi in form of a principle. To date, no poroelastic theory is capable of recovering a stress partitioning law in agreement with Terzaghi's postulated one in the absence of ad hoc constitutive assumptions on the medium. We recently proposed a variational macroscopic continuum description of two-phase poroelasticity to derive a general biphasic formulation at finite deformations, termed variational macroscopic theory of porous media (VMTPM). Such approach proceeds from the inclusion of the intrinsic volumetric strain among the kinematic descriptors aside to macroscopic displacements, and as a variational theory, uses the Hamilton least-action principle as the unique primitive concept of mechanics invoked to derive momentum balance equations. In a previous related work it was shown that, for the subclass of undrained problems, VMTPM predicts that stress is partitioned in the two phases in strict compliance with Terzaghi's law, irrespective of the microstructural and constitutive features of a given medium. In the present contribution, we further develop the linearized framework of VMTPM to arrive at a general operative formula that allows the quantitative determination of stress partitioning in a jacketed test over a generic isotropic biphasic specimen. This formula is quantitative and general, in that it relates the partial phase stresses to the externally applied stress as function of partitioning coefficients that are all derived by strictly following a purely variational and purely macroscopic approach, and in the absence of any specific hypothesis on the microstructural or constitutive features of a given medium. To achieve this result, the stiffness coefficients of the theory are derived by using exclusively variational arguments. We derive the boundary conditions attained across the boundary of a poroelastic saturated medium in contact with an impermeable surface also based on purely variational arguments. A technique to retrieve bounds for the resulting elastic moduli, based on Hashin's composite spheres assemblage method, is also reported. Notably, in spite of the minimal mechanical hypotheses introduced, a rich mechanical behavior is observed.

Coupled fluid and solid mechanics study for improved permeability estimation of fines' invaded porous materials

NASA Astrophysics Data System (ADS)

Mirabolghasemi, M.; Prodanovic, M.

2012-12-01

The problem of fine particle infiltration is seen in fields from subsurface transport, to drug delivery to industrial slurry flows. Sediment filtration and pathogen retention are well-known subsurface engineering problems that have been extensively studied through different macroscopic, microscopic and experimental modeling techniques Due to heterogeneity, standard constitutive relationships and models yield poor predictions for flow (e.g. permeability) and rock properties (e.g. elastic moduli) of the invaded (damaged) porous media. This severely reduces our ability to, for instance, predict retention, pressure build-up, newly formed flow pathways or porous medium mechanical behavior. We chose a coupled computational fluid dynamics (CFD) - discrete element modeling (DEM) approach to simulate the particulate flow through porous media represented by sphere packings. In order to minimize the uncertainty involved in estimating the flow properties of porous media on Darcy scale and address the dynamic nature of filtration process, this microscopic approach is adapted as a robust method that can incorporate particle interaction physics as well as the heterogeneity of the porous medium.. The coupled simulation was done in open-source packages which has both CFD (openFOAM) and DEM components (LIGGGHTS). We ran several sensitivity analyses over different parameters such as particle/grain size ratio, fluid viscosity, flow rate and sphere packing porosity in order to investigate their effects on the depth of invasion and damaged porous medium permeability. The response of the system to the variation of different parameters is reflected through different clogging mechanism; for instance, bridging is the dominant mechanism of pore-throat clogging when larger particles penetrate into the packing, whereas, in case of fine particles which are much smaller than porous medium grains (1/20 in diameter), this mechanism is not very effective due to the frequent formation and destruction of particle bridges. Finally, depending on the material and fluids that penetrate into the porous medium, the ionic forces might play a significant role in the filtration process. We thus also report on influence of particle attachment (and detachment) on the type of clogging mechanisms. Pore scale simulations allow for visualization and understanding of fundamental processes, and, further, the velocity fields are integrated into a distinctly non-monotonic permeability-porosity/(depth of penetration) relationship.

Thermal convection in three-dimensional fractured porous media

NASA Astrophysics Data System (ADS)

Mezon, C.; Mourzenko, V. V.; Thovert, J.-F.; Antoine, R.; Fontaine, F.; Finizola, A.; Adler, P. M.

2018-01-01

Thermal convection is numerically computed in three-dimensional (3D) fluid saturated isotropically fractured porous media. Fractures are randomly inserted as two-dimensional (2D) convex polygons. Flow is governed by Darcy's 2D and 3D laws in the fractures and in the porous medium, respectively; exchanges take place between these two structures. Results for unfractured porous media are in agreement with known theoretical predictions. The influence of parameters such as the fracture aperture (or fracture transmissivity) and the fracture density on the heat released by the whole system is studied for Rayleigh numbers up to 150 in cubic boxes with closed-top conditions. Then, fractured media are compared to homogeneous porous media with the same macroscopic properties. Three major results could be derived from this study. The behavior of the system, in terms of heat release, is determined as a function of fracture density and fracture transmissivity. First, the increase in the output flux with fracture density is linear over the range of fracture density tested. Second, the increase in output flux as a function of fracture transmissivity shows the importance of percolation. Third, results show that the effective approach is not always valid, and that the mismatch between the full calculations and the effective medium approach depends on the fracture density in a crucial way.

Efficient anisotropic quasi-P wavefield extrapolation using an isotropic low-rank approximation

NASA Astrophysics Data System (ADS)

Zhang, Zhen-dong; Liu, Yike; Alkhalifah, Tariq; Wu, Zedong

2018-04-01

The computational cost of quasi-P wave extrapolation depends on the complexity of the medium, and specifically the anisotropy. Our effective-model method splits the anisotropic dispersion relation into an isotropic background and a correction factor to handle this dependency. The correction term depends on the slope (measured using the gradient) of current wavefields and the anisotropy. As a result, the computational cost is independent of the nature of anisotropy, which makes the extrapolation efficient. A dynamic implementation of this approach decomposes the original pseudo-differential operator into a Laplacian, handled using the low-rank approximation of the spectral operator, plus an angular dependent correction factor applied in the space domain to correct for anisotropy. We analyse the role played by the correction factor and propose a new spherical decomposition of the dispersion relation. The proposed method provides accurate wavefields in phase and more balanced amplitudes than a previous spherical decomposition. Also, it is free of SV-wave artefacts. Applications to a simple homogeneous transverse isotropic medium with a vertical symmetry axis (VTI) and a modified Hess VTI model demonstrate the effectiveness of the approach. The Reverse Time Migration applied to a modified BP VTI model reveals that the anisotropic migration using the proposed modelling engine performs better than an isotropic migration.

Measurement techniques of exposure to nanomaterials in the workplace for low- and medium-income countries: A systematic review.

PubMed

Boccuni, Fabio; Gagliardi, Diana; Ferrante, Riccardo; Rondinone, Bruna Maria; Iavicoli, Sergio

2017-10-01

Nanotechnology offers many opportunities but there is still considerable uncertainty about the health risks and how to assess these.In the field of risk analysis for workers potentially exposed to nano-objects and their agglomerates and aggregates (NOAA) different methodological approaches to measure airborne NOAA have been proposed.This study proposes a systematic review of scientific literature on occupational exposure to NOAA in the workplace with the aim to identify techniques of exposure measurement to be recommended in low- and medium-income countries.We gathered scientific papers reporting techniques of NOAA exposure measurements in the workplace, we summarized the data for each eligible technique according to PRISMA guidelines, and we rated the quality of evidence following an adapted GRADE approach.We found 69 eligible studies to be included in qualitative synthesis: the majority of studies reported a moderate quality and only two studies demonstrated the use of a high quality exposure measurement technique.The review demonstrates that a basic exposure measurement, i.e. evidence for the presence or absence of NOAA in the workplace air, can be achieved with moderate (40 techniques) to high (2 techniques) quality; comprehensive exposure measurement, that allow the quantification of NOAA in the workplace, can be achieved with moderate (11 techniques) to high (2 techniques) quality.The findings of the study also allowed to finalize a list of requirements that must be fulfilled by an effective measurement technique (either basic or comprehensive) and to highlight the main weaknesses that need to be tackled for an effective affordability evaluation of measurement techniques to be recommended in low- and medium-income countries. Copyright © 2017 Elsevier GmbH. All rights reserved.

Hypoxic-Preconditioned Bone Marrow Stem Cell Medium Significantly Improves Outcome After Retinal Ischemia in Rats

PubMed Central

Roth, Steven; Dreixler, John C.; Mathew, Biji; Balyasnikova, Irina; Mann, Jacob R.; Boddapati, Venkat; Xue, Lai; Lesniak, Maciej S.

2016-01-01

Purpose We have previously demonstrated the protective effect of bone marrow stem cell (BMSC)-conditioned medium in retinal ischemic injury. We hypothesized here that hypoxic preconditioning of stem cells significantly enhances the neuroprotective effect of the conditioned medium and thereby augments the protective effect in ischemic retina. Methods Rats were subjected to retinal ischemia by increasing intraocular pressure to 130 to 135 mm Hg for 55 minutes. Hypoxic-preconditioned, hypoxic unconditioned, or normoxic medium was injected into the vitreous 24 hours after ischemia ended. Recovery was assessed 7 days after injections by comparing electroretinography measurements, histologic examination, and apoptosis (TUNEL, terminal deoxynucleotidyl transferase–mediated dUTP nick end labeling assay). To compare proteins secreted into the medium in the groups and the effect of hypoxic exposure, we used rat cytokine arrays. Results Eyes injected with hypoxic BMSC–conditioned medium 24 hours after ischemia demonstrated significantly enhanced return of retinal function, decreased retinal ganglion cell layer loss, and attenuated apoptosis compared to those administered normoxic or hypoxic unconditioned medium. Hypoxic-preconditioned medium had 21 significantly increased protein levels compared to normoxic medium. Conclusions The medium from hypoxic-preconditioned BMSCs robustly restored retinal function and prevented cell loss after ischemia when injected 24 hours after ischemia. The protective effect was even more pronounced than in our previous studies of normoxic conditioned medium. Prosurvival signals triggered by the secretome may play a role in this neuroprotective effect. PMID:27367588

Isogeometric frictionless contact analysis with the third medium method

NASA Astrophysics Data System (ADS)

Kruse, R.; Nguyen-Thanh, N.; Wriggers, P.; De Lorenzis, L.

2018-01-01

This paper presents an isogeometric formulation for frictionless contact between deformable bodies, based on the recently proposed concept of the third medium. This concept relies on continuum formulations not only for the contacting bodies but also for a fictitious intermediate medium in which the bodies can move and interact. Key to the formulation is a suitable definition of the constitutive behavior of the third medium. In this work, based on a number of numerical tests, the role of the material parameters of the third medium is systematically assessed. We also assess the rate of spatial convergence for higher-order discretizations, stemming from the regularization of the non-smooth contact problem inherent to the third medium approach. Finally, problems with self contact are considered and turn out to be an attractive application of the method.

Platelet lysate enhances synovial fluid multipotential stromal cells functions: Implications for therapeutic use.

PubMed

Altaie, Ala; Baboolal, Thomas G; Wall, Owen; Jones, Elena; McGonagle, Dennis

2018-03-01

Although intra-articular injection of platelet products is increasingly used for joint regenerative approaches, there are few data on their biological effects on joint-resident multipotential stromal cells (MSCs), which are directly exposed to the effects of these therapeutic strategies. Therefore, this study investigated the effect of platelet lysate (PL) on synovial fluid-derived MSCs (SF-MSCs), which in vivo have direct access to sites of cartilage injury. SF-MSCs were obtained during knee arthroscopic procedures (N = 7). Colony forming unit-fibroblast (CFU-F), flow-cytometric phenotyping, carboxyfluorescein succinimidyl ester-based immunomodulation for T-cell and trilineage differentiation assays were performed using PL and compared with standard conditions. PL-enhanced SF-MSC (PL-MSC) proliferation as CFU-F colonies was 1.4-fold larger, and growing cultures had shorter population-doubling times. PL-MSCs and fetal calf serum (FCS)-MSCs had the same immunophenotype and similar immunomodulation activities. In chondrogenic and osteogenic differentiation assays, PL-MSCs produced 10% more sulfated-glycosaminoglycan (sGAG) and 45% less Ca ++ compared with FCS-MSCs, respectively. Replacing chondrogenic medium transforming growth factor-β3 with 20% or 50% PL further increased sGAG production of PL-MSCs by 69% and 95%, respectively, compared with complete chondrogenic medium. Also, Dulbecco's Modified Eagle's Medium high glucose (HG-DMEM) plus 50% PL induced more chondrogenesis compared with HG-DMEM plus 10% FCS and was comparable to complete chondrogenic medium. This is the first study to assess SF-MSC responses to PL and provides biological support to the hypothesis that PL may be capable of modulating multiple functional aspects of joint resident MSCs with direct access to injured cartilage. Copyright © 2017 International Society for Cellular Therapy. Published by Elsevier Inc. All rights reserved.

In Vitro Effect of Apigenin and Danshen in Tibial Dyschondroplasia Through Inhibition of Heat-Shock Protein 90 and Vascular Endothelial Growth Factor Expressions in Avian Growth Plate Cells.

PubMed

Mehmood, Khalid; Zhang, Hui; Iqbal, Muhammad Kashif; Rehman, Mujeeb Ur; Shahzad, Muhammad; Li, Kun; Huang, Shucheng; Nabi, Fazul; Zhang, Lihong; Li, Jiakui

2017-09-01

Tibial dyschondroplasia (TD) is one of the common skeletal abnormalities in fast-growing birds, and it is characterized by nonvascularized, unmineralized, and nonviable cartilage in the tibial growth plate that fails to form bone. The aim of this study was to check the in vitro effect of apigenin and danshen on heat-shock protein 90 (Hsp90) and vascular endothelial growth factor (VEGF) expressions in avian growth plate cells treated with sublethal concentration of thiram. Initially, chondrocytes from chicken growth plates were isolated on culturx ed medium with and without various concentration of thiram to determine the sublethal dose. Then, to check the effect of apigenin and danshen, the chondrocytes were treated first with a sublethal (2.5 μM) concentration of thiram and then with different doses (10, 20, 40, and 80 μM) of apigenin and danshen. The mRNA expression levels of Hsp90 and VEGF genes were evaluated by quantitative reverse transcription polymerase chain reaction (RT-qPCR). The results showed that the expression levels of Hsp90 and VEGF mRNA transcripts were increased significantly (P < 0.05) in thiram-treated chondrocytes culture medium up to 1.5-fold, whereas apigenin and danshen therapy to chondrocytes in culture medium significantly (P < 0.05) reduced the Hsp90 and VEGF expression levels. In conclusion, up-regulation of both (Hsp90 and VEGF) genes and damage to chondrocytes in culture medium caused by thiram can be restored by using apigenin and danshen. Therefore, apigenin and danshen therapies are suggested and encouraged as a promising approach to control TD in broiler chickens.

REVISITING NUCLEOPHILIC SUBSTITUTION REACTIONS: MICROWAVE-ASSISTED SYNTHESIS OF AZIDES, THIOCYANATES AND SULFONES IN AQUEOUS MEDIUM

EPA Science Inventory

A practical, rapid and efficient microwave (MW) promoted synthesis of various azides, thiocyanates and sulfones, is described in aqueous medium. This general and expeditious MW-enhanced nucleophilic substitution approach uses easily accessible starting materials such as halides o...

Third-order Zeeman effect in highly charged ions

NASA Astrophysics Data System (ADS)

Varentsova, A. S.; Agababaev, V. A.; Volchkova, A. M.; Glazov, D. A.; Volotka, A. V.; Shabaev, V. M.; Plunien, G.

2017-10-01

The contribution of the third order in magnetic field to the Zeeman splitting of the ground state of hydrogenlike, lithiumlike, and boronlike ions in the range Z = 6 - 82 is investigated within the relativistic approach. Both perturbative and non-perturbative methods of calculation are employed and found to be in agreement. For lithiumlike and boronlike ions the interelectronic-interaction effects are taken into account within the approximation of the local screening potential. The contribution of the third-order effect in low- and medium-Z boronlike ions is found to be important for anticipated high-precision measurements.

Quantum yield and rate constant of the singlet 1Δ g oxygen luminescence in an aqueous medium in the presence of nanoscale inhomogeneities

NASA Astrophysics Data System (ADS)

Jarnikova, E. S.; Parkhats, M. V.; Stasheuski, A. S.; Lepeshkevich, S. V.; Dzhagarov, B. M.

2017-04-01

The quantum yields and lifetimes of photosensitized luminescence of the 1Δ g state of singlet oxygen in an aquatic media with a controlled concentration of dielectric anisotropy centers (polyethylene glycol) have been measured using the methods of laser fluorometry. It is established that the quantum yield and the rate constant ( k r ) of the a 1Δ g → X 3Σ g - luminescence of 1O2 increase as the polymer concentration increases. The effect is analyzed within a general approach involving a relationship between kr and dielectric properties of the medium and is explained by the increased density of photon states and the local field factor in the space around O2( a 1Δ g ).

Application of digital control techniques for satellite medium power DC-DC converters

NASA Astrophysics Data System (ADS)

Skup, Konrad R.; Grudzinski, Pawel; Nowosielski, Witold; Orleanski, Piotr; Wawrzaszek, Roman

2010-09-01

The objective of this paper is to present a work concerning a digital control loop system for satellite medium power DC-DC converters that is done in Space Research Centre. The whole control process of a described power converter bases on a high speed digital signal processing. The paper presents a development of a FPGA digital controller for voltage mode stabilization that was implemented using VHDL. The described controllers are a classical digital PID controller and a bang-bang controller. The used converter for testing is a simple model of 5-20 W, 200 kHz buck power converter. A high resolution digital PWM approach is presented. Additionally a simple and effective solution of filtering of an analog-to-digital converter output is presented.

The misleading nature of in vitro and ex vivo findings in studying the impact of stress hormones on NK cell cytotoxicity.

PubMed

Gotlieb, Neta; Rosenne, Ella; Matzner, Pini; Shaashua, Lee; Sorski, Liat; Ben-Eliyahu, Shamgar

2015-03-01

In vitro and ex vivo studies assessing the impact of stress hormones on immune competence commonly replace the natural milieu of leukocytes with an artificial medium, excluding plasma factors, hormones, and cytokines. Given prevalent inconsistencies between in vitro, ex vivo, and in vivo findings, we studied whether such procedures could yield misleading outcomes regarding the impact of stress hormones on NK cell cytotoxicity (NKCC), using fresh human whole blood samples. We found that in the presence of plasma 10-30-fold higher concentrations of cortisol, epinephrine, and prostaglandin-E2 (PGE2) were required to reach suppression levels evident in the context of artificial medium. Importantly, whereas the NK suppressive effects of PGE2 occurred immediately and remained stable upon prolonged exposure, the suppressive effects of cortisol slowly increased over time. Last, to simulate the exclusion of stress factors in the ex vivo approach, we subjected whole blood to stress hormones (as occurs in vivo), and abruptly removed them. We found that the effects of epinephrine and PGE2 quickly disappeared, while the effects of cortisol persisted. Overall, these findings demonstrate the potential misleading nature of in vitro and ex vivo procedures, and specifically suggest that (i) the common in vitro findings of profound suppression of NKCC by stress hormones are overestimation of their direct effects expected in vivo; and (ii) the common ex vivo approach cannot reflect the direct in vivo suppressive effects of epinephrine and PGE2 on NKCC, while inflating the effects of glucocorticoids. Some of these fallacies may be circumvented by using non-delayed whole blood NKCC assays in humans. Copyright © 2014 Elsevier Inc. All rights reserved.

Ensemble superparameterization versus stochastic parameterization: A comparison of model uncertainty representation in tropical weather prediction

NASA Astrophysics Data System (ADS)

Subramanian, Aneesh C.; Palmer, Tim N.

2017-06-01

Stochastic schemes to represent model uncertainty in the European Centre for Medium-Range Weather Forecasts (ECMWF) ensemble prediction system has helped improve its probabilistic forecast skill over the past decade by both improving its reliability and reducing the ensemble mean error. The largest uncertainties in the model arise from the model physics parameterizations. In the tropics, the parameterization of moist convection presents a major challenge for the accurate prediction of weather and climate. Superparameterization is a promising alternative strategy for including the effects of moist convection through explicit turbulent fluxes calculated from a cloud-resolving model (CRM) embedded within a global climate model (GCM). In this paper, we compare the impact of initial random perturbations in embedded CRMs, within the ECMWF ensemble prediction system, with stochastically perturbed physical tendency (SPPT) scheme as a way to represent model uncertainty in medium-range tropical weather forecasts. We especially focus on forecasts of tropical convection and dynamics during MJO events in October-November 2011. These are well-studied events for MJO dynamics as they were also heavily observed during the DYNAMO field campaign. We show that a multiscale ensemble modeling approach helps improve forecasts of certain aspects of tropical convection during the MJO events, while it also tends to deteriorate certain large-scale dynamic fields with respect to stochastically perturbed physical tendencies approach that is used operationally at ECMWF.