Science.gov

Sample records for mesoscopic biological test

  1. Cosmic heavy ion tracks in mesoscopic biological test objects

    NASA Technical Reports Server (NTRS)

    Facius, R.

    1994-01-01

    Since more than 20 years ago, when the National Academy of Sciences and the National Research Council of the U.S.A. released their report on 'HZE particle effects in manned spaced flight', it has been emphasized how difficult - if not even impossible - it is to assess their radiobiological impact on man from conventional studies where biological test organisms are stochastically exposed to 'large' fluences of heavy ions. An alternative, competing approach had been realized in the BIOSTACK experiments, where the effects of single cosmic as well as accelerator - heavy ions on individual biological test organisms could be investigated. Although presented from the beginning as the preferable approach for terrestrial investigations with accelerator heavy ions too ('The BIOSTACK as an approach to high LET radiation research'), only recently this insight is gaining more widespread recognition. In space flight experiments, additional constraints imposed by the infrastructure of the vehicle or satellite further impede such investigations. Restrictions concern the physical detector systems needed for the registration of the cosmic heavy ions' trajectories as well as the biological systems eligible as test organisms. Such optimized procedures and techniques were developed for the investigations on chromosome aberrations induced by cosmic heavy ions in cells of the stem meristem of lettuce seeds (Lactuca sativa) and for the investigation of the radiobiological response of Wolffia arriza, which is the smallest flowering (water) plant. The biological effects were studied by the coworkers of the Russian Institute of Biomedical Problems (IBMP) which in cooperation with the European Space Agency ESA organized the exposure in the Biosatellites of the Cosmos series. Since biological investigations and physical measurements of particle tracks had to be performed in laboratories widely separated, the preferred fixed contact between biological test objects and the particle detectors

  2. Cosmic heavy ion tracks in mesoscopic biological test objects

    SciTech Connect

    Facius, R.

    1994-12-31

    Since more than 20 years ago, when the National Academy of Sciences and the National Research Council of the U.S.A. released their report on `HZE particle effects in manned spaced flight`, it has been emphasized how difficult - if not even impossible - it is to assess their radiobiological impact on man from conventional studies where biological test organisms are stochastically exposed to `large` fluences of heavy ions. An alternative, competing approach had been realized in the BIOSTACK experiments, where the effects of single cosmic as well as accelerator - heavy ions on individual biological test organisms could be investigated. Although presented from the beginning as the preferable approach for terrestrial investigations with accelerator heavy ions too (`The BIOSTACK as an approach to high LET radiation research`), only recently this insight is gaining more widespread recognition. In space flight experiments, additional constraints imposed by the infrastructure of the vehicle or satellite further impede such investigations. Restrictions concern the physical detector systems needed for the registration of the cosmic heavy ions` trajectories as well as the biological systems eligible as test organisms. Such optimized procedures and techniques were developed for the investigations on chromosome aberrations induced by cosmic heavy ions in cells of the stem meristem of lettuce seeds (Lactuca sativa) and for the investigation of the radiobiological response of Wolffia arriza, which is the smallest flowering (water) plant. The biological effects were studied by the coworkers of the Russian Institute of Biomedical Problems (IBMP) which in cooperation with the European Space Agency ESA organized the exposure in the Biosatellites of the Cosmos series.

  3. The IWOP Technique and Wigner-Function Approach to Quantum Effect of Mesoscopic Biological Cell

    NASA Astrophysics Data System (ADS)

    Wang, Xiu-Xia

    2014-09-01

    Using the IWOP technique, Wigner function theory and TFD theory, the quantization of a mesoscopic biological cell equivalent circuit is proposed, The quantum fluctuations of the mesoscopic biological cell are researched in thermal vacuum state and vacuum state. It is shown that the IWOP technique, Wigner function theory and Umezawa-Takahashi's TFD theory play the key role in quantizing a mesoscopic biological cell at finite temperature and the fluctuations and uncertainty increase with increasing temperature and decrease with prolonged time.

  4. cellPACK: A Virtual Mesoscope to Model and Visualize Structural Systems Biology

    PubMed Central

    Johnson, Graham T.; Autin, Ludovic; Al-Alusi, Mostafa; Goodsell, David S.; Sanner, Michel F.; Olson, Arthur J.

    2014-01-01

    cellPACK assembles computational models of the biological mesoscale, an intermediate scale (10−7–10−8m) between molecular and cellular biology. cellPACK’s modular architecture unites existing and novel packing algorithms to generate, visualize and analyze comprehensive 3D models of complex biological environments that integrate data from multiple experimental systems biology and structural biology sources. cellPACK is currently available as open source code, with tools for validation of models and with recipes and models for five biological systems: blood plasma, cytoplasm, synaptic vesicles, HIV and a mycoplasma cell. We have applied cellPACK to model distributions of HIV envelope protein to test several hypotheses for consistency with experimental observations. Biologists, educators, and outreach specialists can interact with cellPACK models, develop new recipes and perform packing experiments through scripting and graphical user interfaces at http://cellPACK.org. PMID:25437435

  5. Crucial tests of macrorealist and semiclassical gravity models with freely falling mesoscopic nanospheres

    NASA Astrophysics Data System (ADS)

    Colin, Samuel; Durt, Thomas; Willox, Ralph

    2016-06-01

    Recently, several proposals have been made to test the quantum superposition principle in the mesoscopic regime. Most of these tests consist of a careful measurement of the loss of interference due to decoherence. Here we consider, instead, the spread in position of a freely falling nanosphere. We study in depth the dependence of this spread on self-gravity in the presence of decoherence (exotic and nonexotic). We show that the influence of self-gravity is robust in the presence of weak decoherence, and quantify this robustness by introducing a parameter, the critical decoherence, aimed at estimating the critical value above which self-gravity is overwhelmed by decoherence. We also emphasize the crucial role played by the spread of the initial wave packet for the sensitivity of free-fall experiments to decoherence.

  6. Mesoscopic Lawlessness

    NASA Astrophysics Data System (ADS)

    Laughlin, R. B.

    2012-02-01

    Whether physics will contribute significantly to unraveling the secrets of life, the grandest challenge of them all, depends critically on whether proteins and other mesoscale objects exhibit emergent law. By this I mean quantitative relationships among their measured properties that are always true. The jury is still out on the matter, for there is evidence both for and against, but it is spotty, on account of the difficulty of measuring 100 nm - 1000 objects without damaging them quantum mechanically. It is therefore not clear that history will repeat itself. Physics contributed mightily to 20th century materials science through its identification and mastery of powerful macroscopic emergent laws such as crystalline rigidity, superconductivity and ferromagnetism, but it cannot do the same thing in biology, regardless of how powerful computers get, unless nature cooperates. The challenge before us as physicists is therefore not to amass more and more terabytes of data and computational output but rather to search for and, with luck, find operating principles at the scale of life greater than those of chemistry, which is to say, greater than a world ruled by nothing but miraculous accidents.

  7. [Exposit in a biological test].

    PubMed

    Hoyer, I; Gängler, P; Will, R; Benkert, O

    1989-01-01

    The biocompatibility of the composite resin materials Exposit and Evicrol was tested by functional studies of the rat incisor and the biological test of the dental pulp of pigs. Exposit shows mainly reversible reactions of the vascular connective tissue both in the vital-microscopical examination of the immediate reaction and in short-term tests (24 hours, 7 days), where positive adaptation reactions (new vessels and revascularization) are to be observed. Evicrol causes distinct and irreversible damages in the pulp of the rat incisor. The results of the vital-microscopical examination are proven by histological checks of the rat incisor. In the morphological picture Exposit shows in pig teeth mainly slight and partly moderate inflammatory pulpal reactions after a period of 30 and 90 days. For Evicrol, however, severe reactions with a massive accumulation of inflammatory cells is to be observed after a period of 30 days. Despite an acceptable and, compared to Evicrol, a better biocompatibility of Exposit there is a demand for an exact pulp protection. PMID:2534010

  8. Complexity at mesoscopic lengthscale.

    PubMed

    Egami, T

    2015-09-01

    Modern materials are often complex in the structure at mesoscale. The method of pair-density function (PDF) is a powerful tool to characterize mesoscopic structure, bridging short- and long-range structures. PMID:26306189

  9. Automatic interpretation of biological tests.

    PubMed

    Boufriche-Boufaïda, Z

    1998-03-01

    In this article, an approach for an Automatic Interpretation of Biological Tests (AIBT) is described. The developed system is much needed in Preventive Medicine Centers (PMCs). It is designed as a self-sufficient system that could be easily used by trained nurses during the routine visit. The results that the system provides are not only useful to provide the PMC physicians with a preliminary diagnosis, but also allows them more time to focus on the serious cases, making the clinical visit more qualitative. On the other hand, because the use of such a system has been planned for many years, its possibilities for future extensions must be seriously considered. The methodology adopted can be interpreted as a combination of the advantages of two main approaches adopted in current diagnostic systems: the production system approach and the object-oriented system approach. From the rules, the ability of these approaches to capture the deductive processes of the expert in domains where causal mechanisms are often understood are retained. The object-oriented approach guides the elicitation and the engineering of knowledge in such a way that abstractions, categorizations and classifications are encouraged whilst individual instances of objects of any type are recognized as separate, independent entities. PMID:9684093

  10. Apparatus for automated testing of biological specimens

    DOEpatents

    Layne, Scott P.; Beugelsdijk, Tony J.

    1999-01-01

    An apparatus for performing automated testing of infections biological specimens is disclosed. The apparatus comprise a process controller for translating user commands into test instrument suite commands, and a test instrument suite comprising a means to treat the specimen to manifest an observable result, and a detector for measuring the observable result to generate specimen test results.

  11. Electron waiting times for the mesoscopic capacitor

    NASA Astrophysics Data System (ADS)

    Hofer, Patrick P.; Dasenbrook, David; Flindt, Christian

    2016-08-01

    We evaluate the distribution of waiting times between electrons emitted by a driven mesoscopic capacitor. Based on a wave packet approach we obtain analytic expressions for the electronic waiting time distribution and the joint distribution of subsequent waiting times. These semi-classical results are compared to a full quantum treatment based on Floquet scattering theory and good agreement is found in the appropriate parameter ranges. Our results provide an intuitive picture of the electronic emissions from the driven mesoscopic capacitor and may be tested in future experiments.

  12. - and Perovskite-Sensitised Mesoscopic Solar Cells

    NASA Astrophysics Data System (ADS)

    Grätzel, Michael; Durrant, James R.

    2015-10-01

    The following sections are included: * Introduction * Historical background * Mode of function of dye-sensitised solar cells * DSSC research and development * Solid-state mesoscopic cells based on molecular dyes or perovskite pigments as sensitisers * Pilot production of modules, field tests and commercial DSSC development * Outlook * Acknowledgements * References

  13. Entanglement of mesoscopic systems

    NASA Astrophysics Data System (ADS)

    Narnhofer, Heide; Thirring, Walter

    2002-11-01

    The entanglement of clouds of N=1011 atoms recently experimentally verified is expressed in terms of the fluctuation algebra introduced by [P. Goderis, A. Verbeure, and P. Vets, Commun. Phys. 128, 533 (1990)]. A mean-field Hamiltonian describing the coupling to a laser beam leads to different time evolutions if considered on microscopic or mesoscopic operators. Only the latter creates nontrivial correlations that finally after a measurement lead to entanglement between the clouds.

  14. Biomonitoring test procedures and biological criteria

    SciTech Connect

    Kszos, L.A.; Lipschultz, M.J.; Foster, W.E.

    1997-10-01

    The Water Environment Federation recently issued a special publication, Biomonitoring in the Water Environment. In this paper, the authors highlight the contents of the chapter 3, Biomonitoring Test Procedures, identify current trends in test procedures and introduce the concept of biological criteria (biocriteria). The book chapter (and this paper) focuses on freshwater and marine chronic and acute toxicity tests used in the National Pollutant Discharge Elimination System (NPDES) permits program to identify effluents and receiving waters containing toxic materials in acutely or chronically toxic concentrations. The two major categories of toxicity tests include acute tests and chronic tests. The USEPA chronic tests required in NPDEs permits have been shortened to 7 days by focusing on the most sensitive life-cycle stages; these tests are often referred to as short-term chronic tests. The type of test(s) required depend on NPDES permit requirements, objectives of the test, available resources, requirements of the test organisms, and effluent characteristics such as variability in flow or toxicity. The permit writer will determine the requirements for toxicity test(s) by considering such factors as dilution, effluent variability, and exposure variability. Whether the required test is acute or chronic, the objective of the test is to estimate the safe or no effect concentration which is defined as the concentration which will permit normal propagation of fish and other aquatic life in the receiving waters. In this paper, the authors review the types of toxicity tests, the commonly used test organisms, and the uses of toxicity test data. In addition, they briefly describe research on new methods and the use of biological criteria.

  15. Unit testing, model validation, and biological simulation

    PubMed Central

    Watts, Mark D.; Ghayoomie, S. Vahid; Larson, Stephen D.; Gerkin, Richard C.

    2016-01-01

    The growth of the software industry has gone hand in hand with the development of tools and cultural practices for ensuring the reliability of complex pieces of software. These tools and practices are now acknowledged to be essential to the management of modern software. As computational models and methods have become increasingly common in the biological sciences, it is important to examine how these practices can accelerate biological software development and improve research quality. In this article, we give a focused case study of our experience with the practices of unit testing and test-driven development in OpenWorm, an open-science project aimed at modeling Caenorhabditis elegans. We identify and discuss the challenges of incorporating test-driven development into a heterogeneous, data-driven project, as well as the role of model validation tests, a category of tests unique to software which expresses scientific models.

  16. Seismoelectric effects due to mesoscopic heterogeneities

    NASA Astrophysics Data System (ADS)

    Jougnot, Damien; Rubino, J. GermáN.; Carbajal, Marina Rosas; Linde, Niklas; Holliger, Klaus

    2013-05-01

    While the seismic effects of wave-induced fluid flow due to mesoscopic heterogeneities have been studied for several decades, the role played by these types of heterogeneities on seismoelectric phenomena is largely unexplored. To address this issue, we have developed a novel methodological framework which allows for the coupling of wave-induced fluid flow, as inferred through numerical oscillatory compressibility tests, with the pertinent seismoelectric conversion mechanisms. Simulating the corresponding response of a water-saturated sandstone sample containing mesoscopic fractures, we demonstrate for the first time that these kinds of heterogeneities can produce measurable seismoelectric signals under typical laboratory conditions. Given that this phenomenon is sensitive to key hydraulic and mechanical properties, we expect that the results of this pilot study will stimulate further exploration on this topic in several domains of the Earth, environmental, and engineering sciences.

  17. Mesoscopic modelling of columnar solidification

    NASA Astrophysics Data System (ADS)

    Založnik, M.; Viardin, A.; Souhar, Y.; Combeau, H.; Apel, M.

    2016-03-01

    We used two complementary modeling approaches for the simulation of columnar growth in directional solidification of organic alloys: a phase-field model and a mesoscopic envelope model of dendritic growth. While the phase-field method captures the details of the dendritic structure and of the growth dynamics, the mesoscopic model approximates the complex dendritic morphology by its envelope. The envelope growth is deduced from the velocities of the dendrite tips, calculated by an analytical LGK-type tip model that is matched to the heat and concentration fields in the stagnant film around the envelope. The computational cost of the mesoscopic model is several orders of magnitude lower and can bridge the gap between phase-field and macroscopic models. We demonstrate the applicability of the mesoscopic model to columnar growth and discuss its possibilities and limitations by comparisons with phase-field simulations for the same conditions.

  18. [Which biological matrix for cannabis testing?].

    PubMed

    Goullé, J-P; Lacroix, C

    2006-05-01

    Decisive analytical progress for biological cannabis testing has been achieved over the past ten years. These major contributions allow to accurately identify and quantify in detail the substances present in the body following cannabinoid exposure. Fast and reliable onsite urine testing is used to implement the French law on narcotic drugs and its relationship to motorway safety. A positive test result will indicate a very recent exposure which is detectable up to five days following intake. Then a clinical examination and blood collection are performed by a physician, with a subsequent blood tetrahydrocannabinol (THC) analysis by authorized professionals registered at the judicial court of appeal. A result higher than the cut-off value is associated with a very recent cannabis exposure. Blood, urine, saliva and sweat cannabis determination are assessed according to the most recent pharmacokinetic and analytical data. PMID:16710116

  19. Prospective Tests on Biological Models of Acupuncture

    PubMed Central

    2009-01-01

    The biological effects of acupuncture include the regulation of a variety of neurohumoral factors and growth control factors. In science, models or hypotheses with confirmed predictions are considered more convincing than models solely based on retrospective explanations. Literature review showed that two biological models of acupuncture have been prospectively tested with independently confirmed predictions: The neurophysiology model on the long-term effects of acupuncture emphasizes the trophic and anti-inflammatory effects of acupuncture. Its prediction on the peripheral effect of endorphin in acupuncture has been confirmed. The growth control model encompasses the neurophysiology model and suggests that a macroscopic growth control system originates from a network of organizers in embryogenesis. The activity of the growth control system is important in the formation, maintenance and regulation of all the physiological systems. Several phenomena of acupuncture such as the distribution of auricular acupuncture points, the long-term effects of acupuncture and the effect of multimodal non-specific stimulation at acupuncture points are consistent with the growth control model. The following predictions of the growth control model have been independently confirmed by research results in both acupuncture and conventional biomedical sciences: (i) Acupuncture has extensive growth control effects. (ii) Singular point and separatrix exist in morphogenesis. (iii) Organizers have high electric conductance, high current density and high density of gap junctions. (iv) A high density of gap junctions is distributed as separatrices or boundaries at body surface after early embryogenesis. (v) Many acupuncture points are located at transition points or boundaries between different body domains or muscles, coinciding with the connective tissue planes. (vi) Some morphogens and organizers continue to function after embryogenesis. Current acupuncture research suggests a convergence

  20. Mesoscopic simulations of recrystallization

    SciTech Connect

    Holm, E.A.; Rollett, A.D.; Srolovitz, D.J.

    1995-08-01

    The application of computer simulation to grain growth and recrystallization was strongly stimulated in the early 80s by the realization that Monte Carlo models could be applied to problems of grain structure evolution. By extension of the Ising model for domain modeling of magnetic domains to the Potts model (with generalized spin numbers) it was then possible to represent discretely grains (domains) by regions of similarly oriented sets of material (lattice) points. In parallel with this fascinating development, there also occured notable work on analytical models, especially by Abbruzzese and Bunge, which has been particularly useful for understanding the variation of texture (crystallographic preferred orientation) during grain growth processes. Geometric models of recrystallization, worked on most recently and productively by Nes et al., have been useful in connection with grain size prediction as a result of recrystallization. Also, mesh-based models have been developed to a high degree by Kawasaki, Fradkov and others, and, rather recently, by Humphreys to model not just grain growth but also the nucleation process in recrystallization. These models have the strength that they deal with the essential features of grains, i.e. the nodes, but have some limitations when second phases must be considered. These various approaches to modeling of recrystallization processes will be reviewed, with a special emphasis on practical approaches to implementing the Potts model. This model has been remarkably successful in modeling such diverse phenomena as dynamic recrystallization, secondary recrystallization (abnormal grain growth), particle-inhibited recrystallization, and grain structure evolution in soldering and welding. In summary, the application of mesoscopic simulation to the phenomenon of recrystallization has yielded much new insight into some longstanding deficiencies in our understanding.

  1. What can we learn from noise? - Mesoscopic nonequilibrium statistical physics.

    PubMed

    Kobayashi, Kensuke

    2016-01-01

    Mesoscopic systems - small electric circuits working in quantum regime - offer us a unique experimental stage to explorer quantum transport in a tunable and precise way. The purpose of this Review is to show how they can contribute to statistical physics. We introduce the significance of fluctuation, or equivalently noise, as noise measurement enables us to address the fundamental aspects of a physical system. The significance of the fluctuation theorem (FT) in statistical physics is noted. We explain what information can be deduced from the current noise measurement in mesoscopic systems. As an important application of the noise measurement to statistical physics, we describe our experimental work on the current and current noise in an electron interferometer, which is the first experimental test of FT in quantum regime. Our attempt will shed new light in the research field of mesoscopic quantum statistical physics. PMID:27477456

  2. Raise Test Scores: Integrate Biology and Calculus.

    ERIC Educational Resources Information Center

    Lukens, Jeffrey D.; Feinstein, Sheryl

    This paper presents the results of research that compared the academic achievement of high school students enrolled in an integrated Advanced Placement Biology/Advanced Placement Calculus course with students enrolled in traditional Advanced Placement Biology and Advanced Placement Calculus courses. Study subjects included high school students…

  3. TESTING AND EVALUATION IN THE BIOLOGICAL SCIENCES.

    ERIC Educational Resources Information Center

    NELSON, CLARENCE H.

    THIS REPORT OF THE CUEBS PANEL ON EDUCATION AND TESTING SERVES AS A RESOURCE FOR THE INSTRUCTOR PREPARING COURSE EXAMINATIONS. THE MAJOR TOPICS DISCUSSED ARE (1) THE PROCEDURES IN PREPARING AN ACHIEVEMENT TEST, (2) THE CATEGORIZATION AND CODING OF TEST ITEMS, AND (3) THE ADVANTAGES AND LIMITATIONS OF VARIOUS TESTING PROCEDURES. OVER 1300 OBJECTIVE…

  4. Statistics and Hypothesis Testing in Biology.

    ERIC Educational Resources Information Center

    Maret, Timothy J.; Ziemba, Robert E.

    1997-01-01

    Suggests that early in their education students be taught to use basic statistical tests as rigorous methods of comparing experimental results with scientific hypotheses. Stresses that students learn how to use statistical tests in hypothesis-testing by applying them in actual hypothesis-testing situations. To illustrate, uses questions such as…

  5. DNA-programmed mesoscopic architecture.

    PubMed

    Halverson, Jonathan D; Tkachenko, Alexei V

    2013-06-01

    We study the problem of the self-assembly of nanoparticles (NPs) into finite mesoscopic structures with a programmed local morphology and complex overall shape. Our proposed building blocks are NPs that are directionally functionalized with DNA. The combination of directionality and selectivity of interactions allows one to avoid unwanted metastable configurations, which have been shown to lead to slow self-assembly kinetics even in much simpler systems. With numerical simulations, we show that a variety of target mesoscopic objects can be designed and self-assembled in near perfect yield. They include cubes, pyramids, boxes, and even an Empire State Building model. We summarize our findings with a set of design strategies that leads to the successful self-assembly of a wide range of mesostructures. PMID:23848678

  6. DNA-programmed mesoscopic architecture

    NASA Astrophysics Data System (ADS)

    Halverson, Jonathan D.; Tkachenko, Alexei V.

    2013-06-01

    We study the problem of the self-assembly of nanoparticles (NPs) into finite mesoscopic structures with a programmed local morphology and complex overall shape. Our proposed building blocks are NPs that are directionally functionalized with DNA. The combination of directionality and selectivity of interactions allows one to avoid unwanted metastable configurations, which have been shown to lead to slow self-assembly kinetics even in much simpler systems. With numerical simulations, we show that a variety of target mesoscopic objects can be designed and self-assembled in near perfect yield. They include cubes, pyramids, boxes, and even an Empire State Building model. We summarize our findings with a set of design strategies that leads to the successful self-assembly of a wide range of mesostructures.

  7. Multidimensional Computerized Adaptive Testing for Indonesia Junior High School Biology

    ERIC Educational Resources Information Center

    Kuo, Bor-Chen; Daud, Muslem; Yang, Chih-Wei

    2015-01-01

    This paper describes a curriculum-based multidimensional computerized adaptive test that was developed for Indonesia junior high school Biology. In adherence to the Indonesian curriculum of different Biology dimensions, 300 items was constructed, and then tested to 2238 students. A multidimensional random coefficients multinomial logit model was…

  8. Gravitational decoherence for mesoscopic systems

    NASA Astrophysics Data System (ADS)

    Adler, Stephen L.; Bassi, Angelo

    2016-01-01

    We extend the recent gravitational decoherence analysis of Pikovski et al. to an individual mesoscopic system with internal state characterized by a coherent superposition of energy eigenstates. We express the Pikovski et al. effect directly in terms of the energy variance, and show that the interferometric visibility is bounded from below. Hence unlike collisional decoherence, the visibility does not approach zero at large times, although for a large system it can become very small.

  9. Mesoscopic Superposition States in Relativistic Landau Levels

    SciTech Connect

    Bermudez, A.; Martin-Delgado, M. A.; Solano, E.

    2007-09-21

    We show that a linear superposition of mesoscopic states in relativistic Landau levels can be built when an external magnetic field couples to a relativistic spin 1/2 charged particle. Under suitable initial conditions, the associated Dirac equation produces unitarily superpositions of coherent states involving the particle orbital quanta in a well-defined mesoscopic regime. We demonstrate that these mesoscopic superpositions have a purely relativistic origin and disappear in the nonrelativistic limit.

  10. Radiative Transfer on Mesoscopic Spatial Scales

    NASA Astrophysics Data System (ADS)

    Gardner, Adam Ronald

    Accurate predictions of light transport produced by illumination of turbid media such as biological tissues, cloudy atmospheres, terrestrial surfaces, and soft matter is essential in many applications including remote sensing, functional optical imaging, realistic image synthesis, and materials characterization. The inability to model light transport on mesoscopic scales limits the spatial resolution and information content that can be extracted from optical measurements. While effective approaches exist to model light transport in singly- and diffusely-scattering regimes, modeling light propagation over the mesoscopic spatial scales remains an important challenge. Radiative transfer on these scales must account for the complete 5-dimensional spatial and angular distributions of the radiant field. Here, we present novel stochastic and analytic methods to analyze and predict light propagation in turbid media generated by collimated illumination on mesoscopic scales. We also consider coupled transport problems, resulting from illumination and detection, to facilitate measurement design and inverse problems. Specifically, we introduce a coupled Forward-Adjoint Monte Carlo (cFAMC) method that leverages generalized optical reciprocity to enable the computation of spatially-resolved distributions of light interrogation for specific source-detector pairs. cFAMC can aid the design of optical diagnostic measurements by tailoring the light field to interrogate specific sub-volumes of interest. We use cFAMC to examine the effects of angular resolution on the resulting interrogation distributions and analyze a diagnostically-relevant compact fiber probe design for the detection of epithelial precancer. While Monte Carlo simulation is considered a gold standard method to solve the equation of radiative transfer (ERT), it is computationally expensive. Thus, methods to obtain ERT solutions at lower computational cost are valuable. We introduce a general analytical framework to

  11. CHIRONOMIDAE TOXICITY TESTS--BIOLOGICAL BACKGROUND AND PROCEDURES

    EPA Science Inventory

    Toxicity tests must be based on an understanding of the test animal's life cycle. The first section of this report describes the biological information needed to develop toxicity test procedures. The second section describes three categories of toxicity test systems - short-expos...

  12. Nonsymmetrized Correlations in Mesoscopic Current Measurements

    NASA Astrophysics Data System (ADS)

    Belzig, Wolfgang; Bednorz, Adam; Bruder, Christoph; Reulet, Bertrand

    2014-03-01

    A long-standing problem in quantum mesoscopic physics is which operator order corresponds to noise expressions like < I(ω) I(- ω) > , where I(ω) is the measured current at frequency ω. Symmetrized order describes a classical measurement while nonsymmetrized order corresponds to a quantum detector, e.g., one sensitive to either emission or absorption of photons. We show that both order schemes can be embedded in quantum weak-measurement theory taking into account measurements with memory, characterized by a memory function which is independent of a particular experimental detection scheme [A. Bednorz, C. Bruder, B. Reulet, and W. Belzig, Phys. Rev. Lett. 110, 250404 (2013)]. We discuss the resulting quasiprobabilities for different detector temperatures and how their negativity can be tested on the level of second-order correlation functions already. Experimentally, this negativity can be related to the squeezing of the many-body state of the transported electrons in an ac-driven tunnel junction.

  13. Mesoscopic electronics beyond DC transport

    NASA Astrophysics Data System (ADS)

    di Carlo, Leonardo

    Since the inception of mesoscopic electronics in the 1980's, direct current (dc) measurements have underpinned experiments in quantum transport. Novel techniques complementing dc transport are becoming paramount to new developments in mesoscopic electronics, particularly as the road is paved toward quantum information processing. This thesis describes seven experiments on GaAs/AlGaAs and graphene nanostructures unified by experimental techniques going beyond traditional dc transport. Firstly, dc current induced by microwave radiation applied to an open chaotic quantum dot is investigated. Asymmetry of mesoscopic fluctuations of induced current in perpendicular magnetic field is established as a tool for separating the quantum photovoltaic effect from classical rectification. A differential charge sensing technique is next developed using integrated quantum point contacts to resolve the spatial distribution of charge inside a double quantum clot. An accurate method for determining interdot tunnel coupling and electron temperature using charge sensing is demonstrated. A two-channel system for detecting current noise in mesoscopic conductors is developed, enabling four experiments where shot noise probes transmission properties not available in dc transport and Johnson noise serves as an electron thermometer. Suppressed shot noise is observed in quantum point contacts at zero parallel magnetic field, associated with the 0.7 structure in conductance. This suppression evolves with increasing field into the shot-noise signature of spin-lifted mode degeneracy. Quantitative agreement is found with a phenomenological model for density-dependent mode splitting. Shot noise measurements of multi-lead quantum-dot structures in the Coulomb blockade regime distill the mechanisms by which Coulomb interaction and quantum indistinguishability correlate electron flow. Gate-controlled sign reversal of noise cross correlation in two capacitively-coupled dots is observed, and shown to

  14. Using synthetic biology to make cells tomorrow's test tubes.

    PubMed

    Garcia, Hernan G; Brewster, Robert C; Phillips, Rob

    2016-04-18

    The main tenet of physical biology is that biological phenomena can be subject to the same quantitative and predictive understanding that physics has afforded in the context of inanimate matter. However, the inherent complexity of many of these biological processes often leads to the derivation of complex theoretical descriptions containing a plethora of unknown parameters. Such complex descriptions pose a conceptual challenge to the establishment of a solid basis for predictive biology. In this article, we present various exciting examples of how synthetic biology can be used to simplify biological systems and distill these phenomena down to their essential features as a means to enable their theoretical description. Here, synthetic biology goes beyond previous efforts to engineer nature and becomes a tool to bend nature to understand it. We discuss various recent and classic experiments featuring applications of this synthetic approach to the elucidation of problems ranging from bacteriophage infection, to transcriptional regulation in bacteria and in developing embryos, to evolution. In all of these examples, synthetic biology provides the opportunity to turn cells into the equivalent of a test tube, where biological phenomena can be reconstituted and our theoretical understanding put to test with the same ease that these same phenomena can be studied in the in vitro setting. PMID:26952708

  15. Combined biological tests for suicide prediction

    PubMed Central

    Coryell, William; Schlesser, Michael

    2007-01-01

    Disturbances in serotonin neuroregulation and in hypothalamic-pituitary-adrenal axis activity are both likely, and possibly independent, factors in the genesis of suicidal behavior. This analysis considers whether clinically accessible measures of these two disturbances have additive value in the estimation of risk for suicide. Seventy-four inpatients with RDC major or schizoaffective depressive disorders entered a prospective follow-up study from 1978–1981, underwent a dexamethasone suppression test (DST) and had fasting serum cholesterol levels available in the medical record. As reported earlier, patients who had had an abnormal DST result were significantly more likely to commit suicide during follow-up. Serum cholesterol concentrations did not differ by DST result and low cholesterol values were associated with subsequent suicide when age and sex were included as covariates. These results indicate that, with the use of age-appropriate thresholds, serum cholesterol concentrations may be combined with DST results to provide a clinically useful estimate of suicide risk. PMID:17289156

  16. Biologic concentration testing in inflammatory bowel disease.

    PubMed

    Vaughn, Byron P; Sandborn, William J; Cheifetz, Adam S

    2015-06-01

    Anti-TNF medications have revolutionized the care of patients with inflammatory bowel disease. However, despite an initial robust effect, loss of response is common and long-term results are disappointing. Much of this lack of durability may be due to inadequate dose optimization, and recent studies suggest a correlation between serum drug concentrations and clinical outcomes. Currently, in clinical practice, measurement of drug concentrations and antibodies to drug are typically performed only when a patient presents with active inflammatory bowel disease symptoms or during a potential immune-mediated reaction to anti-TNF ("reactive" setting). However, proactive monitoring of anti-TNF concentrations with titration to a therapeutic window (i.e., therapeutic concentration monitoring) represents a new strategy with many potential clinical benefits including prevention of immunogenicity, less need for IFX rescue therapy, and greater durability of IFX treatment. This review will cover the salient features of anti-TNF pharmacokinetics and pharmacodynamics and provide a rational approach for the use of anti-TNF concentration testing in both the reactive and proactive settings. PMID:25590953

  17. A test system for the biological safety cabinet

    PubMed Central

    Newsom, S. W. B.

    1974-01-01

    A simple, cheap and readily available test system for biological safety cabinets is described. It depends on the containment of an aerosol of Bacillus subtilis spores generated in a BIRD micronebulizer and the measurement of air flows with an anemometer. The system was set up to survey new equipment but equally valuable results have been obtained from tests during use. New units were often badly installed and used equipment was poorly maintained. It is suggested that any department which has a need for a biological safety cabinet must be in a position to test its function. Images PMID:4214380

  18. UNDERSTANDINGS OF BSCS BIOLOGY STUDENTS AS DETERMINED BY INSTRUCTIONAL TESTS.

    ERIC Educational Resources Information Center

    ROBINSON, JAMES T.

    EIGHT INSTRUCTIONAL TESTS SPANNED THE CURRICULUM OF ONE YEAR OF BIOLOGY STUDY. THE FIRST CONCERNED THE NATURE OF SCIENCE INCLUDED 4 AREAS OF EMPHASIS--THE NATURE AND FUNCTION OF HYPOTHESIS, THE IDEA OF CONTROLS IN EXPERIMENTS, INTERPRETATION OF GRAPHED DATA, AND THE NATURE OF DATA. THE SECOND TEST WAS DESIGNED TO SHOW AN UNDERSTANDING OF…

  19. Energy Cost of Controlling Mesoscopic Quantum Systems

    NASA Astrophysics Data System (ADS)

    Horowitz, Jordan M.; Jacobs, Kurt

    2015-09-01

    We determine the minimum energy required to control the evolution of any mesoscopic quantum system in the presence of arbitrary Markovian noise processes. This result provides the mesoscopic equivalent of the fundamental cost of refrigeration, sets the minimum power consumption of mesoscopic devices that operate out of equilibrium, and allows one to calculate the efficiency of any control protocol, whether it be open-loop or feedback control. As examples, we calculate the energy cost of maintaining a qubit in the ground state and the efficiency of resolved-sideband cooling of nano-mechanical resonators, and discuss the energy cost of quantum information processing.

  20. New challenges and opportunities in nonclinical safety testing of biologics.

    PubMed

    Baumann, Andreas; Flagella, Kelly; Forster, Roy; de Haan, Lolke; Kronenberg, Sven; Locher, Mathias; Richter, Wolfgang F; Theil, Frank-Peter; Todd, Marque

    2014-07-01

    New challenges and opportunities in nonclinical safety testing of biologics were discussed at the 3rd European BioSafe Annual General Membership meeting in November 2013 in Berlin: (i)Approaches to refine use of non-human primates in non-clinical safety testing of biologics and current experience on the use of minipigs as alternative non-rodent species.(ii)Tissue distribution studies as a useful tool to support pharmacokinetic/pharmacodynamic (PKPD) assessment of biologics, in that they provide valuable mechanistic insights at drug levels at the site of action.(iii)Mechanisms of nonspecific toxicity of antibody drug conjugates (ADC) and ways to increase the safety margins.(iv)Although biologics toxicity typically manifests as exaggerated pharmacology there are some reported case studies on unexpected toxicity.(v)Specifics of non-clinical development approaches of noncanonical monoclonal antibodies (mAbs), like bispecifics and nanobodies. PMID:24755365

  1. Mesoscopic Modelling of Financial Markets

    NASA Astrophysics Data System (ADS)

    Cordier, Stephane; Pareschi, Lorenzo; Piatecki, Cyrille

    2009-01-01

    We derive a mesoscopic description of the behavior of a simple financial market where the agents can create their own portfolio between two investment alternatives: a stock and a bond. The model is derived starting from the Levy-Levy-Solomon microscopic model (Levy et al. in Econ. Lett. 45:103-111, 1994; Levy et al. in Microscopic Simulation of Financial Markets: From Investor Behavior to Market Phenomena, Academic Press, San Diego, 2000) using the methods of kinetic theory and consists of a linear Boltzmann equation for the wealth distribution of the agents coupled with an equation for the price of the stock. From this model, under a suitable scaling, we derive a Fokker-Planck equation and show that the equation admits a self-similar lognormal behavior. Several numerical examples are also reported to validate our analysis.

  2. Current challenges and opportunities in nonclinical safety testing of biologics.

    PubMed

    Kronenberg, Sven; Baumann, Andreas; de Haan, Lolke; Hinton, Heather J; Moggs, Jonathan; Theil, Frank-Peter; Wakefield, Ian; Singer, Thomas

    2013-12-01

    Nonclinical safety testing of new biotherapeutic entities represents its own challenges and opportunities in drug development. Hot topics in this field have been discussed recently at the 2nd Annual BioSafe European General Membership Meeting. In this feature article, discussions on the challenges surrounding the use of PEGylated therapeutic proteins, selection of cynomolgus monkey as preclinical species, unexpected pharmacokinetics of biologics and the safety implications thereof are summarized. In addition, new developments in immunosafety testing of biologics, the use of transgenic mouse models and PK and safety implications of multispecific targeting approaches are discussed. Overall, the increasing complexity of new biologic modalities and formats warrants tailor-made nonclinical development strategies and experimental testing. PMID:23942260

  3. Seismological Field Observation of Mesoscopic Nonlinearity

    NASA Astrophysics Data System (ADS)

    Sens-Schönfelder, Christoph; Gassenmeier, Martina; Eulenfeld, Tom; Tilmann, Frederik; Korn, Michael; Niederleithinger, Ernst

    2016-04-01

    Noise based observations of seismic velocity changes have been made in various environments. We know of seasonal changes of velocities related to ground water or temperature changes, co-seismic changes originating from shaking or stress redistribution and changes related to volcanic activity. Is is often argued that a decrease of velocity is related to the opening of cracks while the closure of cracks leads to a velocity increase if permanent stress changes are invoked. In contrast shaking induced changes are often related to "damage" and subsequent "healing" of the material. The co-seismic decrease and transient recovery of seismic velocities can thus be explained with both - static stress changes or damage/healing processes. This results in ambiguous interpretations of the observations. Here we present the analysis of one particular seismic station in northern Chile that shows very strong and clear velocity changes associated with several earthquakes ranging from Mw=5.3 to Mw=8.1. The fact that we can observe the response to several events of various magnitudes from different directions offers the unique possibility to discern the two possible causative processes. We test the hypothesis, that the velocity changes are related to shaking rather than stress changes by developing an empirical model that is based on the local ground acceleration at the sensor site. The eight year of almost continuous observations of velocity changes are well modeled by a daily drop of the velocity followed by an exponential recovery. Both, the amplitude of the drop as well as the recovery time are proportional to the integrated acceleration at the seismic station. Effects of consecutive days are independent and superimposed resulting in strong changes after earthquakes and constantly increasing velocities during quiet days thereafter. This model describes the continuous observations of the velocity changes solely based on the acceleration time series without individually defined dates

  4. Mesoscopic model of actin-based propulsion.

    PubMed

    Zhu, Jie; Mogilner, Alex

    2012-01-01

    Two theoretical models dominate current understanding of actin-based propulsion: microscopic polymerization ratchet model predicts that growing and writhing actin filaments generate forces and movements, while macroscopic elastic propulsion model suggests that deformation and stress of growing actin gel are responsible for the propulsion. We examine both experimentally and computationally the 2D movement of ellipsoidal beads propelled by actin tails and show that neither of the two models can explain the observed bistability of the orientation of the beads. To explain the data, we develop a 2D hybrid mesoscopic model by reconciling these two models such that individual actin filaments undergoing nucleation, elongation, attachment, detachment and capping are embedded into the boundary of a node-spring viscoelastic network representing the macroscopic actin gel. Stochastic simulations of this 'in silico' actin network show that the combined effects of the macroscopic elastic deformation and microscopic ratchets can explain the observed bistable orientation of the actin-propelled ellipsoidal beads. To test the theory further, we analyze observed distribution of the curvatures of the trajectories and show that the hybrid model's predictions fit the data. Finally, we demonstrate that the model can explain both concave-up and concave-down force-velocity relations for growing actin networks depending on the characteristic time scale and network recoil. To summarize, we propose that both microscopic polymerization ratchets and macroscopic stresses of the deformable actin network are responsible for the force and movement generation. PMID:23133366

  5. Testing of Synthetic Biological Membranes for Forward Osmosis Applications

    NASA Technical Reports Server (NTRS)

    Parodi, Jurek; Mangado, Jaione Romero; Stefanson, Ofir; Flynn, Michael; Mancinelli, Rocco; Kawashima, Brian; Trieu, Serena; Brozell, Adrian; Rosenberg, Kevan

    2016-01-01

    Commercially available forward osmosis membranes have been extensively tested for human space flight wastewater treatment. Despite the improvements achieved in the last decades, there is still a challenge to produce reliable membranes with anti-fouling properties, chemical resistance, and high flux and selectivity. Synthetic biological membranes that mimic the ones present in nature, which underwent millions of years of evolution, represent a potential solution for further development and progress in membrane technology. Biomimetic forward osmosis membranes based on a polymeric support filter and coated with surfactant multilayers have been engineered to investigate how different manufacturing processes impact the performance and structure of the membrane. However, initial results of the first generation prototype membranes tests reveal a high scatter in the data, due to the current testing apparatus set up. The testing apparatus has been upgraded to improve data collection, reduce errors, and to allow higher control of the testing process.

  6. Wave basin model tests of technical-biological bank protection

    NASA Astrophysics Data System (ADS)

    Eisenmann, J.

    2012-04-01

    Sloped embankments of inland waterways are usually protected from erosion and other negative im-pacts of ship-induced hydraulic loads by technical revetments consisting of riprap. Concerning the dimensioning of such bank protection there are several design rules available, e.g. the "Principles for the Design of Bank and Bottom Protection for Inland Waterways" or the Code of Practice "Use of Standard Construction Methods for Bank and Bottom Protection on Waterways" issued by the BAW (Federal Waterways Engineering and Research Institute). Since the European Water Framework Directive has been put into action special emphasis was put on natural banks. Therefore the application of technical-biological bank protection is favoured. Currently design principles for technical-biological bank protection on inland waterways are missing. The existing experiences mainly refer to flowing waters with no or low ship-induced hydraulic loads on the banks. Since 2004 the Federal Waterways Engineering and Research Institute has been tracking the re-search and development project "Alternative Technical-Biological Bank Protection on Inland Water-ways" in company with the Federal Institute of Hydrology. The investigation to date includes the ex-amination of waterway sections where technical- biological bank protection is applied locally. For the development of design rules for technical-biological bank protection investigations shall be carried out in a next step, considering the mechanics and resilience of technical-biological bank protection with special attention to ship-induced hydraulic loads. The presentation gives a short introduction into hydraulic loads at inland waterways and their bank protection. More in detail model tests of a willow brush mattress as a technical-biological bank protec-tion in a wave basin are explained. Within the scope of these tests the brush mattresses were ex-posed to wave impacts to determine their resilience towards hydraulic loads. Since the

  7. Analytical Methods in Mesoscopic Systems

    NASA Astrophysics Data System (ADS)

    Mason, Douglas Joseph

    The prospect of designing technologies around the quantum behavior of mesoscopic devices is enticing. This thesis present several tools to facilitate the process of calculating and analyzing the quantum properties of such devices - resonance, boundary conditions, and the quantum-classical correspondence are major themes that we study with these tools. In Chapter 1, we begin by laying the groundwork for the tools that follow by defining the Hamiltonian, the Green's function, the scattering matrix, and the Landauer formalism for ballistic conduction. In Chapter 2, we present an efficient and easy-to-implement algorithm called the Outward Wave Algorithm, which calculates the conductance function and scattering density matrix when a system is coupled to an environment in a variety of geometries and contexts beyond the simple two-lead schematic. In Chapter 3, we present a unique geometry and numerical method called the Boundary Reflectin Matrix that allows us to calculate the full scattering matrix from arbitrary boundaries of a lattice system, and introduce the phenomenon of internal Bragg diffraction. In Chapter 4, we present a new method for visualizing wavefunctions called the Husimi map, which uses measurement by coherent states to form a bridge between the quantum flux operator and semiclassics. We extend the formalism from Chapter 4 to lattice systems in Chapter 5, and comment on our results in Chapter 3 and other work in the literature. These three tools - the Outward Wave Algorithm, the Boundary Reflection Matrix, and the Husimi map - work together to throw light on our interpretation of resonance and scattering in quantum systems, effectively codifying the expertise developed in semiclassics over the past few decades in an efficient and robust package. The data and images that they make available promise to help design better technologies based on quantum scattering.

  8. Proposal of a magnetohyperthermia system: preliminary biological tests

    NASA Astrophysics Data System (ADS)

    Guedes, M. H. A.; Guedes, M. E. A.; Morais, P. C.; Da Silva, M. F.; Santos, T. S.; Alves, J. P.; Bertelli, C. E.; Azevedo, R. B.; Lacava, Z. G. M.

    2004-05-01

    Magnetohyperthermia (MHT) has been proposed as an alternative therapy for cancer treatment. In order to perform MHT tests we have developed an apparatus operating at 1 MHz with AC magnetic field of 40 Oe in amplitude. Biological tests were performed after exposing the peritoneum region of mice to the AC field. Significative alterations were observed only when peritoneum was exposed by 10 min. The data allowed to conclude that: (1) the damage induced by the AC field to normal cells is related to the exposure time and (2) the equipment developed is adequate to perform MHT experiments.

  9. Stable planar mesoscopic photonic crystal cavities.

    PubMed

    Magno, G; Monmayrant, A; Grande, M; Lozes-Dupuy, F; Gauthier-Lafaye, O; Calò, G; Petruzzelli, V

    2014-07-15

    Mesoscopic self-collimation (MSC) in mesoscopic photonic crystals with high reflectivity is exploited to realize a novel high Q-factor cavity by means of mesoscopic PhC planar mirrors. These mirrors efficiently confine a mode inside a planar Fabry-Perot-like cavity, that results from a beam focusing effect that stabilizes the cavity even for small beam sizes, resembling the focusing behavior of curved mirrors. Moreover, they show an improved reflectivity with respect to their standard distributed Bragg reflector counterparts that allows higher compactness. A Q-factor higher than 10⁴ has been achieved for an optimized 5-period-long mirror cavity. The optimization of the Q-factor and the performances in terms of energy storage, field enhancement, and confinement are detailed. PMID:25121692

  10. Statistical tests for measures of colocalization in biological microscopy.

    PubMed

    McDonald, John H; Dunn, Kenneth W

    2013-12-01

    Colocalization analysis is the most common technique used for quantitative analysis of fluorescence microscopy images. Several metrics have been developed for measuring the colocalization of two probes, including Pearson's correlation coefficient (PCC) and Manders' correlation coefficient (MCC). However, once measured, the meaning of these measurements can be unclear; interpreting PCC or MCC values requires the ability to evaluate the significance of a particular measurement, or the significance of the difference between two sets of measurements. In previous work, we showed how spatial autocorrelation confounds randomization techniques commonly used for statistical analysis of colocalization data. Here we use computer simulations of biological images to show that the Student's one-sample t-test can be used to test the significance of PCC or MCC measurements of colocalization, and the Student's two-sample t-test can be used to test the significance of the difference between measurements obtained under different experimental conditions. PMID:24117417

  11. A mesoscopic model for (de)wetting.

    PubMed

    Merabia, S; Pagonabarraga, I

    2006-06-01

    We present a mesoscopic model for simulating the dynamics of a non-volatile liquid on a solid substrate. The wetting properties of the solid can be tuned from complete wetting to total non-wetting. This model opens the way to study the dynamics of drops and liquid thin films at mesoscopic length scales of the order of the nanometer. As particular applications, we analyze the kinetics of spreading of a liquid drop wetting a solid substrate and the dewetting of a liquid film on a hydrophobic substrate. In all these cases, very good agreement is found between simulations and theoretical predictions. PMID:16775662

  12. A study of fatigue mesoscopic elasto-plastic properties of a nickel-base superalloy by instrumented microindentation measurements

    NASA Astrophysics Data System (ADS)

    Ye, Duyi; Cha, Haibo; Xiao, Lei; Xu, Xuandong

    2012-01-01

    In this study the fatigue mesoscopic elasto-plastic properties of nickel-base superalloy GH4145/SQ were investigated using the instrumented microindentation testing coupled with the analytic calculation. The indentation characteristic parameters of low-cycle fatigue specimens, such as the indentation curvature ( C), the maximum penetration depth ( hmax), the initial unloading slope ( S), the residual depth of penetration ( h r), the recovered elastic work ( W e) and the residual plastic work ( W p), were determined from the experimental load-penetration depth ( P- h) curves, and the fatigue mesoscopic elasto-plastic properties ( E, σ y and n) were estimated using a well-developed analysis algorithm proposed by Dao et al. The distribution patterns of the fatigue mesoscopic mechanical properties were further verified in a statistical sense. The dependence of the fatigue mesoscopic elasto-plastic properties upon the imposed strain amplitude was discussed preliminarily in terms of microstructural examinations of fatigue failure specimens.

  13. Parity effect in a mesoscopic Fermi gas

    NASA Astrophysics Data System (ADS)

    Hofmann, Johannes; Lobos, Alejandro M.; Galitski, Victor

    2016-06-01

    We develop a quantitative analytic theory that accurately describes the odd-even effect observed experimentally in a one-dimensional, trapped Fermi gas with a small number of particles [G. Zürn et al., Phys. Rev. Lett. 111, 175302 (2013), 10.1103/PhysRevLett.111.175302]. We find that the underlying physics is similar to the parity effect known to exist in ultrasmall mesoscopic superconducting grains and atomic nuclei. However, in contrast to superconducting nanograins, the density (Hartree) correction dominates over the superconducting pairing fluctuations and leads to a much more pronounced odd-even effect in the mesoscopic, trapped Fermi gas. We calculate the corresponding parity parameter and separation energy using both perturbation theory and a path integral framework in the mesoscopic limit, generalized to account for the effects of the trap, pairing fluctuations, and Hartree corrections. Our results are in an excellent quantitative agreement with experimental data and exact diagonalization. Finally, we discuss a few-particle to many-particle crossover between the perturbative mesoscopic regime and nonperturbative many-body physics that the system approaches in the thermodynamic limit.

  14. Mesoscopic Rings with Spin-Orbit Interactions

    ERIC Educational Resources Information Center

    Berche, Bertrand; Chatelain, Christophe; Medina, Ernesto

    2010-01-01

    A didactic description of charge and spin equilibrium currents on mesoscopic rings in the presence of spin-orbit interaction is presented. Emphasis is made on the non-trivial construction of the correct Hamiltonian in polar coordinates, the calculation of eigenvalues and eigenfunctions and the symmetries of the ground-state properties. Spin…

  15. The mesoscopic modeling of laser ablation

    NASA Astrophysics Data System (ADS)

    Stoneham, A. M.; Ramos, M. M. D.; Ribeiro, R. M.

    It is common to look at the atomic processes of removal of atoms or ions from surfaces. At this microscopic scale, one has to understand which surface ions are involved, which excited states are created, how electrons are transferred and scattered, and how the excitation leads to ion removal. It is even more common to look at continuum models of energy deposition in solids, and at the subsequent heat transfer. In these macroscopic analyses, thermal conduction is combined with empirical assumptions about surface binding. Both these pictures are useful, and both pictures have weaknesses. The atomistic pictures concentrate on relatively few atoms, and do not recognize structural features or the energy and carrier fluxes on larger scales. The continuum macroscopic models leave out crystallographic information and the interplay of the processes with high nonequilibrium at smaller scales. Fortunately, there is a middle way: mesoscopic modeling, which both models the key microstructural features and provides a link between microscopic and macroscopic. In a mesoscopic model, the length scale is determined by the system; often this scale is similar to the grain size. Microstructural features like grain boundaries or dislocations are considered explicitly. The time scale in a mesoscopic model is determined by the ablation process (such as the pulse length) rather than the short time limitations of molecular dynamics, yet the highly nonequilibrium behavior is adequately represented. Mesoscopic models are especially important when key process rates vary on a short length scale. Some microstructural feature (like those in dentine or dental enamel) may absorb light much more than others; other features (like grain boundaries) may capture carriers readily, or allow easier evaporation, or capture and retain charge (like grain boundaries); it is these processes which need a mesoscopic analysis. The results described will be taken largely from the work on MgO of Ribeiro, Ramos, and

  16. Toxicity testing and instream biological monitoring in evaluating municipal effluents

    SciTech Connect

    Krier, K.; Pontasch, K.

    1995-12-31

    Twelve streams receiving municipal wastewater treatment plant effluents were evaluated in riffle areas above and below the outfall using the Environmental Protection Agency`s Rapid Bioassessment Protocols (RBPs) for benthic macroinvertebrates. Eight of the sites evaluated using RBP 1 exhibited stream health in the downstream riffles equaling or exceeding the upstream riffles. RBP 1 results suggested possible impacts at the remaining four sites, and these sites were more intensely evaluated using RBPs 2 and 3, acute effluent toxicity tests with Daphnia magna, and quantification of periphytic chlorophyll a and ash free dry weight (AFDW). Results from RBP 2 indicated three of the four sites evaluated have similar taxonomic richness above and below the outfall, while one site is heavily impacted by organic pollutants. Toxicity tests with 100% effluent resulted in no mortality with any of the four effluents tested. Relative to the respective upstream sites, chlorophyll a was significantly increased at one downstream site and significantly reduced at another. AFDW was similar above and below the outfalls in all streams. These results suggest that laboratory toxicity tests may not always be adequate predictors of instream biological effects.

  17. Membrane characteristics for biological blast overpressure testing using blast simulators.

    PubMed

    Alphonse, Vanessa D; Siva Sai Sujith Sajja, Venkata; Kemper, Andrew R; Rizel, Dave V; Duma, Stefan M; VandeVord, Pamela J

    2014-01-01

    Blast simulators often use passive-rupture membranes to generate shock waves similar to free-field blasts. The purpose of this study was to compare rupture patterns and pressure traces of three distinct membrane materials for biological and biomechanical blast studies. An Advanced Blast Simulator (ABS) located at the Center for Injury Biomechanics at Virginia Tech was used to test membrane characteristics. Acetate, Mylar, and aluminum sheets with different thicknesses were used to obtain pressures between 70–210 kPa. Static pressure was measured inside the tube at the test section using piezoelectric pressure sensors. Peak overpressure, positive duration, and positive impulse were calculated for each test. Rupture patterns and characteristic pressure traces were unique to each membrane type and thickness. Shock wave speed ranged between 1.2-1.8 Mach for static overpressures of 70–210 kPa. Acetate membranes fragmented sending pieces down the tube, but produced ideal (Friedlander) pressure traces. Mylar membranes bulged without fragmenting, but produced less-than-ideal pressure traces. Aluminum membranes did not fragment and produced ideal pressure traces. However, the cost of manufacturing and characterizing aluminum membranes should be considered during membrane selection. This study illustrates the advantages and disadvantages of using Mylar, acetate, and aluminum for passive rupture membranes for blast simulators. PMID:25405432

  18. Mesoscopic structure conditions the emergence of cooperation on social networks

    SciTech Connect

    Lozano, S.; Arenas, A.; Sanchez, A.

    2008-12-01

    We study the evolutionary Prisoner's Dilemma on two social networks substrates obtained from actual relational data. We find very different cooperation levels on each of them that cannot be easily understood in terms of global statistical properties of both networks. We claim that the result can be understood at the mesoscopic scale, by studying the community structure of the networks. We explain the dependence of the cooperation level on the temptation parameter in terms of the internal structure of the communities and their interconnections. We then test our results on community-structured, specifically designed artificial networks, finding a good agreement with the observations in both real substrates. Our results support the conclusion that studies of evolutionary games on model networks and their interpretation in terms of global properties may not be sufficient to study specific, real social systems. Further, the study allows us to define new quantitative parameters that summarize the mesoscopic structure of any network. In addition, the community perspective may be helpful to interpret the origin and behavior of existing networks as well as to design structures that show resilient cooperative behavior.

  19. Mesoscopic Structure Conditions the Emergence of Cooperation on Social Networks

    PubMed Central

    Lozano, Sergi; Arenas, Alex; Sánchez, Angel

    2008-01-01

    Background We study the evolutionary Prisoner's Dilemma on two social networks substrates obtained from actual relational data. Methodology/Principal Findings We find very different cooperation levels on each of them that cannot be easily understood in terms of global statistical properties of both networks. We claim that the result can be understood at the mesoscopic scale, by studying the community structure of the networks. We explain the dependence of the cooperation level on the temptation parameter in terms of the internal structure of the communities and their interconnections. We then test our results on community-structured, specifically designed artificial networks, finding a good agreement with the observations in both real substrates. Conclusion Our results support the conclusion that studies of evolutionary games on model networks and their interpretation in terms of global properties may not be sufficient to study specific, real social systems. Further, the study allows us to define new quantitative parameters that summarize the mesoscopic structure of any network. In addition, the community perspective may be helpful to interpret the origin and behavior of existing networks as well as to design structures that show resilient cooperative behavior. PMID:18382673

  20. Harvesting dissipated energy with a mesoscopic ratchet

    NASA Astrophysics Data System (ADS)

    Roche, B.; Roulleau, P.; Jullien, T.; Jompol, Y.; Farrer, I.; Ritchie, D. A.; Glattli, D. C.

    2015-04-01

    The search for new efficient thermoelectric devices converting waste heat into electrical energy is of major importance. The physics of mesoscopic electronic transport offers the possibility to develop a new generation of nanoengines with high efficiency. Here we describe an all-electrical heat engine harvesting and converting dissipated power into an electrical current. Two capacitively coupled mesoscopic conductors realized in a two-dimensional conductor form the hot source and the cold converter of our device. In the former, controlled Joule heating generated by a voltage-biased quantum point contact results in thermal voltage fluctuations. By capacitive coupling the latter creates electric potential fluctuations in a cold chaotic cavity connected to external leads by two quantum point contacts. For unequal quantum point contact transmissions, a net electrical current is observed proportional to the heat produced.

  1. Harvesting dissipated energy with a mesoscopic ratchet.

    PubMed

    Roche, B; Roulleau, P; Jullien, T; Jompol, Y; Farrer, I; Ritchie, D A; Glattli, D C

    2015-01-01

    The search for new efficient thermoelectric devices converting waste heat into electrical energy is of major importance. The physics of mesoscopic electronic transport offers the possibility to develop a new generation of nanoengines with high efficiency. Here we describe an all-electrical heat engine harvesting and converting dissipated power into an electrical current. Two capacitively coupled mesoscopic conductors realized in a two-dimensional conductor form the hot source and the cold converter of our device. In the former, controlled Joule heating generated by a voltage-biased quantum point contact results in thermal voltage fluctuations. By capacitive coupling the latter creates electric potential fluctuations in a cold chaotic cavity connected to external leads by two quantum point contacts. For unequal quantum point contact transmissions, a net electrical current is observed proportional to the heat produced. PMID:25828578

  2. A NONLINEAR MESOSCOPIC ELASTIC CLASS OF MATERIALS

    SciTech Connect

    P. JOHNSON; R. GUYER; L. OSTROVSKY

    1999-09-01

    It is becoming clear that the elastic properties of rock are shared by numerous other materials (sand, soil, some ceramics, concrete, etc.). These materials have one or more of the following properties in common strong nonlinearity, hysteresis in stress-strain relation, slow dynamics and discrete memory. Primarily, it is the material's compliance, the mesoscopic linkages between the rigid components, that give these materials their unusual elastic properties.

  3. Quantum gambling using mesoscopic ring qubits

    NASA Astrophysics Data System (ADS)

    Pakuła, Ireneusz

    2007-07-01

    Quantum Game Theory provides us with new tools for practising games and some other risk related enterprices like, for example, gambling. The two party gambling protocol presented by Goldenberg {\\it et al} is one of the simplest yet still hard to implement applications of Quantum Game Theory. We propose potential physical realisation of the quantum gambling protocol with use of three mesoscopic ring qubits. We point out problems in implementation of such game.

  4. Entropy production in mesoscopic stochastic thermodynamics: nonequilibrium kinetic cycles driven by chemical potentials, temperatures, and mechanical forces.

    PubMed

    Qian, Hong; Kjelstrup, Signe; Kolomeisky, Anatoly B; Bedeaux, Dick

    2016-04-20

    Nonequilibrium thermodynamics (NET) investigates processes in systems out of global equilibrium. On a mesoscopic level, it provides a statistical dynamic description of various complex phenomena such as chemical reactions, ion transport, diffusion, thermochemical, thermomechanical and mechanochemical fluxes. In the present review, we introduce a mesoscopic stochastic formulation of NET by analyzing entropy production in several simple examples. The fundamental role of nonequilibrium steady-state cycle kinetics is emphasized. The statistical mechanics of Onsager's reciprocal relations in this context is elucidated. Chemomechanical, thermomechanical, and enzyme-catalyzed thermochemical energy transduction processes are discussed. It is argued that mesoscopic stochastic NET in phase space provides a rigorous mathematical basis of fundamental concepts needed for understanding complex processes in chemistry, physics and biology. This theory is also relevant for nanoscale technological advances. PMID:26986039

  5. Entropy production in mesoscopic stochastic thermodynamics: nonequilibrium kinetic cycles driven by chemical potentials, temperatures, and mechanical forces

    NASA Astrophysics Data System (ADS)

    Qian, Hong; Kjelstrup, Signe; Kolomeisky, Anatoly B.; Bedeaux, Dick

    2016-04-01

    Nonequilibrium thermodynamics (NET) investigates processes in systems out of global equilibrium. On a mesoscopic level, it provides a statistical dynamic description of various complex phenomena such as chemical reactions, ion transport, diffusion, thermochemical, thermomechanical and mechanochemical fluxes. In the present review, we introduce a mesoscopic stochastic formulation of NET by analyzing entropy production in several simple examples. The fundamental role of nonequilibrium steady-state cycle kinetics is emphasized. The statistical mechanics of Onsager’s reciprocal relations in this context is elucidated. Chemomechanical, thermomechanical, and enzyme-catalyzed thermochemical energy transduction processes are discussed. It is argued that mesoscopic stochastic NET in phase space provides a rigorous mathematical basis of fundamental concepts needed for understanding complex processes in chemistry, physics and biology. This theory is also relevant for nanoscale technological advances.

  6. Seismoelectric effects caused by mesoscopic heterogeneities

    NASA Astrophysics Data System (ADS)

    Germán Rubino, J.; Jougnot, Damien; Rosas Carbajal, Marina; Linde, Niklas; Holliger, Klaus

    2013-04-01

    When a seismic wave propagates through a fluid saturated porous medium, it produces a relative motion between the fluid phase and the rock matrix. In the presence of an electric double layer at the fluid-solid interface, this movement introduces a separation of electrical charges which in turn generates a time-varying electrical source current and a resulting distribution of electrical potential. The presence of mesoscopic heterogeneities, that is, heterogeneities having sizes larger than the typical pore size but smaller than the prevailing wavelength, can induce a significant oscillatory fluid flow in response to the propagation of seismic waves. Indeed, the energy dissipation related to this phenomenon is considered to be one of the most common and important seismic attenuation mechanisms operating in the shallow part of the crust. Given that the amount of fluid flow produced by this phenomenon can be significant, a potentially important seismoelectric signal is also expected in such media. However, to the best of the authors' knowledge, the role played by mesoscopic wave-induced fluid flow on seismoelectric phenomenon is so far largely unexplored. In this work, we propose a numerical approach for computing seismoelectric signals related to the presence of mesoscopic heterogeneities. To this end, we consider a two-dimensional representative rock sample containing mesoscopic heterogeneities and apply an oscillatory compression on its top boundary. The solid phase is neither allowed to move on the bottom boundary nor to have horizontal displacements on the lateral boundaries and the fluid is not allowed to flow into or out of the sample. The fluid velocity field is determined by solving the quasi-static poroelastic equations in the space-frequency domain under the governing boundary conditions. Next, the seismoelectric conversion is calculated using the so-called effective electrical excess charge approach, which has been recently developed in streaming potential

  7. Mesoscopic organization reveals the constraints governing Caenorhabditis elegans nervous system.

    PubMed

    Pan, Raj Kumar; Chatterjee, Nivedita; Sinha, Sitabhra

    2010-01-01

    One of the biggest challenges in biology is to understand how activity at the cellular level of neurons, as a result of their mutual interactions, leads to the observed behavior of an organism responding to a variety of environmental stimuli. Investigating the intermediate or mesoscopic level of organization in the nervous system is a vital step towards understanding how the integration of micro-level dynamics results in macro-level functioning. The coordination of many different co-occurring processes at this level underlies the command and control of overall network activity. In this paper, we have considered the somatic nervous system of the nematode Caenorhabditis elegans, for which the entire neuronal connectivity diagram is known. We focus on the organization of the system into modules, i.e., neuronal groups having relatively higher connection density compared to that of the overall network. We show that this mesoscopic feature cannot be explained exclusively in terms of considerations such as, optimizing for resource constraints (viz., total wiring cost) and communication efficiency (i.e., network path length). Even including information about the genetic relatedness of the cells cannot account for the observed modular structure. Comparison with other complex networks designed for efficient transport (of signals or resources) implies that neuronal networks form a distinct class. This suggests that the principal function of the network, viz., processing of sensory information resulting in appropriate motor response, may be playing a vital role in determining the connection topology. Using modular spectral analysis we make explicit the intimate relation between function and structure in the nervous system. This is further brought out by identifying functionally critical neurons purely on the basis of patterns of intra- and inter-modular connections. Our study reveals how the design of the nervous system reflects several constraints, including its key

  8. Current Correlations from a Mesoscopic Anyon Collider.

    PubMed

    Rosenow, Bernd; Levkivskyi, Ivan P; Halperin, Bertrand I

    2016-04-15

    Fermions and bosons are fundamental realizations of exchange statistics, which governs the probability for two particles being close to each other spatially. Anyons in the fractional quantum Hall effect are an example for exchange statistics intermediate between bosons and fermions. We analyze a mesoscopic setup in which two dilute beams of anyons collide with each other, and relate the correlations of current fluctuations to the probability of particles excluding each other spatially. While current correlations for fermions vanish, negative correlations for anyons are a clear signature of a reduced spatial exclusion as compared to fermions. PMID:27127979

  9. Quantum measurement of a mesoscopic spin ensemble

    SciTech Connect

    Giedke, G.; Taylor, J. M.; Lukin, M. D.; D'Alessandro, D.; Imamoglu, A.

    2006-09-15

    We describe a method for precise estimation of the polarization of a mesoscopic spin ensemble by using its coupling to a single two-level system. Our approach requires a minimal number of measurements on the two-level system for a given measurement precision. We consider the application of this method to the case of nuclear-spin ensemble defined by a single electron-charged quantum dot: we show that decreasing the electron spin dephasing due to nuclei and increasing the fidelity of nuclear-spin-based quantum memory could be within the reach of present day experiments.

  10. Mesoscopic systems: classical irreversibility and quantum coherence.

    PubMed

    Barbara, Bernard

    2012-09-28

    Mesoscopic physics is a sub-discipline of condensed-matter physics that focuses on the properties of solids in a size range intermediate between bulk matter and individual atoms. In particular, it is characteristic of a domain where a certain number of interacting objects can easily be tuned between classical and quantum regimes, thus enabling studies at the border of the two. In magnetism, such a tuning was first realized with large-spin magnetic molecules called single-molecule magnets (SMMs) with archetype Mn(12)-ac. In general, the mesoscopic scale can be relatively large (e.g. micrometre-sized superconducting circuits), but, in magnetism, it is much smaller and can reach the atomic scale with rare earth (RE) ions. In all cases, it is shown how quantum relaxation can drastically reduce classical irreversibility. Taking the example of mesoscopic spin systems, the origin of irreversibility is discussed on the basis of the Landau-Zener model. A classical counterpart of this model is described enabling, in particular, intuitive understanding of most aspects of quantum spin dynamics. The spin dynamics of mesoscopic spin systems (SMM or RE systems) becomes coherent if they are well isolated. The study of the damping of their Rabi oscillations gives access to most relevant decoherence mechanisms by different environmental baths, including the electromagnetic bath of microwave excitation. This type of decoherence, clearly seen with spin systems, is easily recovered in quantum simulations. It is also observed with other types of qubits such as a single spin in a quantum dot or a superconducting loop, despite the presence of other competitive decoherence mechanisms. As in the molecular magnet V(15), the leading decoherence terms of superconducting qubits seem to be associated with a non-Markovian channel in which short-living entanglements with distributions of two-level systems (nuclear spins, impurity spins and/or charges) leading to 1/f noise induce τ(1)-like

  11. Dormancy and Recovery Testing for Biological Wastewater Processors

    NASA Technical Reports Server (NTRS)

    Hummerick, Mary F.; Coutts, Janelle L.; Lunn, Griffin M.; Spencer, LaShelle; Khodadad, Christina L.; Birmele, Michele N.; Frances, Someliz; Wheeler, Raymond

    2015-01-01

    Resource recovery and recycling waste streams to usable water via biological water processors is a plausible component of an integrated water purification system. Biological processing as a pretreatment can reduce the load of organic carbon and nitrogen compounds entering physiochemical systems downstream. Aerated hollow fiber membrane bioreactors, have been proposed and studied for a number of years as an approach for treating wastewater streams for space exploration.

  12. Optomechanical tests of hydrated biological tissues subjected to laser shaping

    SciTech Connect

    Omel'chenko, A I; Sobol', E N

    2008-03-31

    The mechanical properties of a matrix are studied upon changing the size and shape of biological tissues during dehydration caused by weak laser-induced heating. The cartilage deformation, dehydration dynamics, and hydraulic conductivity are measured upon laser heating. The hydrated state and the shape of samples of separated fascias and cartilaginous tissues were controlled by using computer-aided processing of tissue images in polarised light. (laser biology)

  13. Vestigial Biological Structures: A Classroom-Applicable Test of Creationist Hypotheses

    ERIC Educational Resources Information Center

    Senter, Phil; Ambrocio, Zenis; Andrade, Julia B.; Foust, Katanya K.; Gaston, Jasmine E.; Lewis, Ryshonda P.; Liniewski, Rachel M.; Ragin, Bobby A.; Robinson, Khanna L.; Stanley, Shane G.

    2015-01-01

    Lists of vestigial biological structures in biology textbooks are so short that some young-Earth creationist authors claim that scientists have lost confidence in the existence of vestigial structures and can no longer identify any verifiable ones. We tested these hypotheses with a method that is easily adapted to biology classes. We used online…

  14. Analysis of mesoscopic attenuation in gas-hydrate bearing sediments

    NASA Astrophysics Data System (ADS)

    Rubino, J. G.; Ravazzoli, C. L.; Santos, J. E.

    2007-05-01

    Several authors have shown that seismic wave attenuation combined with seismic velocities constitute a useful geophysical tool to infer the presence and amounts of gas hydrates lying in the pore space of the sediments. However, it is still not fully understood the loss mechanism associated to the presence of the hydrates, and most of the works dealing with this problem focuse on macroscopic fluid flow, friction between hydrates and sediment matrix and squirt flow. It is well known that an important cause of the attenuation levels observed in seismic data from some sedimentary regions is the mesoscopic loss mechanism, caused by heterogeneities in the rock and fluid properties greater than the pore size but much smaller than the wavelengths. In order to analyze this effect in heterogeneous gas-hydrate bearing sediments, we developed a finite-element procedure to obtain the effective complex modulus of an heterogeneous porous material containing gas hydrates in its pore space using compressibility tests at different oscillatory frequencies in the seismic range. The complex modulus were obtained by solving Biot's equations of motion in the space-frequency domain with appropriate boundary conditions representing a gedanken laboratory experiment measuring the complex volume change of a representative sample of heterogeneous bulk material. This complex modulus in turn allowed us to obtain the corresponding effective phase velocity and quality factor for each frequency and spatial gas hydrate distribution. Physical parameters taken from the Mallik 5L-38 Gas Hydrate Research well (Mackenzie Delta, Canada) were used to analyze the mesoscopic effects in realistic hydrated sediments.

  15. Mesoscopic pinning forces in neutron star crusts

    NASA Astrophysics Data System (ADS)

    Seveso, S.; Pizzochero, P. M.; Grill, F.; Haskell, B.

    2016-02-01

    The crust of a neutron star is thought to be comprised of a lattice of nuclei immersed in a sea of free electrons and neutrons. As the neutrons are superfluid, their angular momentum is carried by an array of quantized vortices. These vortices can pin to the nuclear lattice and prevent the neutron superfluid from spinning down, allowing it to store angular momentum which can then be released catastrophically, giving rise to a pulsar glitch. A crucial ingredient for this model is the maximum pinning force that the lattice can exert on the vortices, as this allows us to estimate the angular momentum that can be exchanged during a glitch. In this paper, we perform, for the first time, a detailed and quantitative calculation of the pinning force per unit length acting on a vortex immersed in the crust and resulting from the mesoscopic vortex-lattice interaction. We consider realistic vortex tensions, allow for displacement of the nuclei and average over all possible orientations of the crystal with respect to the vortex. We find that, as expected, the mesoscopic pinning force becomes weaker for longer vortices and is generally much smaller than previous estimates, based on vortices aligned with the crystal. Nevertheless, the forces we obtain still have maximum values of the order of fpin ≈ 1015 dyn cm-1, which would still allow for enough angular momentum to be stored in the crust to explain large Vela glitches, if part of the star is decoupled during the event.

  16. Mesoscopic Physics of Electrons and Photons

    NASA Astrophysics Data System (ADS)

    Akkermans, Eric; Montambaux, Gilles

    2001-12-01

    Quantum mesoscopic physics covers a whole class in interference effects related to the propagation of waves in complex and random media. These effects are ubiquitous in physics, from the behaviour of electrons in metals and semiconductors to the propagation of electromagnetic waves in suspensions such as colloids, and quantum systems like cold atomic gases. A solid introduction to quantum mesoscopic physics, this book is a modern account of the problem of coherent wave propagation in random media. It provides a unified account of the basic theoretical tools and methods, highlighting the common aspects of the various optical and electronic phenomena involved and presenting a large number of experimental results. With over 200 figures, and exercises throughout, the book is ideal for graduate students in physics, electrical engineering, applied physics, acoustics and astrophysics. It will also be an interesting reference for researchers in this rapidly evolving field. Presents a large number of experimental results to give readers a broad overview of the field Self-contained, with all elementary presentations of the necessary basic theories in quantum mechanics and scattering theory Contains exercises throughout the book to help readers understand the concepts

  17. The Mesoscopic Electrochemistry of Molecular Junctions

    NASA Astrophysics Data System (ADS)

    Bueno, Paulo R.; Benites, Tiago A.; Davis, Jason J.

    2016-01-01

    Within the context of an electron dynamic (time-dependent) perspective and a voltage driving force acting to redistribute electrons between metallic and addressable molecular states, we define here the associated electron admittance and conductance. We specifically present a mesoscopic approach to resolving the electron transfer rate associated with the electrochemistry of a redox active film tethered to metallic leads and immersed in electrolyte. The methodology is centred on aligning the lifetime of the process of electron exchange with associated resistance and capacitance quantities. Notably, however, these are no longer those empirically known as charge transfer resistance and pseudo-capacitance, but are those derived instead from a consideration of the quantum states contained in molecular films and their accessibility through a scattering region existing between them and the metallic probe. The averaged lifetime (τr) associated with the redox site occupancy is specifically dependent on scattering associated with the quantum channels linking them to the underlying metallic continuum and associated with both a quantum resistance (Rq) and an electrochemical (redox) capacitance (Cr). These are related to electron transfer rate through k = 1/τr = (RqCr)-1. The proposed mesoscopic approach is consistent with Marcus’s (electron transfer rate) theory and experimental measurements obtained by capacitance spectroscopy.

  18. Mesoscopic Simulation Methods for Polymer Dynamics

    NASA Astrophysics Data System (ADS)

    Larson, Ronald

    2015-03-01

    We assess the accuracy and efficiency of mesoscopic simulation methods, namely Brownian Dynamics (BD), Stochastic Rotation Dynamics (SRD) and Dissipative Particle Dynamics (DPD), for polymers in solution at equilibrium and in flows in microfluidic geometries. Both SRD and DPD use solvent ``particles'' to carry momentum, and so account automatically for hydrodynamic interactions both within isolated polymer coils, and with other polymer molecules and with nearby solid boundaries. We assess quantitatively the effects of artificial particle inertia and fluid compressibility and show that they can be made small with appropriate choice of simulation parameters. We then use these methods to study flow-induced migration of polymer chains produced by: 1) hydrodynamic interactions, 2) streamline curvature or stress-gradients, and 3) convection of wall depletion zones. We show that huge concentration gradients can be produced by these mechanisms in microfluidic geometries that can be exploited for separation of polymers by size in periodic contraction-expansion geometries. We also assess the range of conditions for which BD, SRD or DPD is preferable for mesoscopic simulations. Finally, we show how such methods can be used to simulate quantitatively the swimming of micro-organisms such as E. coli. In collaboration with Lei Jiang and Tongyang Zhao, University of Michigan, Ann Arbor, MI.

  19. The Mesoscopic Electrochemistry of Molecular Junctions

    PubMed Central

    Bueno, Paulo R.; Benites, Tiago A.; Davis, Jason J.

    2016-01-01

    Within the context of an electron dynamic (time-dependent) perspective and a voltage driving force acting to redistribute electrons between metallic and addressable molecular states, we define here the associated electron admittance and conductance. We specifically present a mesoscopic approach to resolving the electron transfer rate associated with the electrochemistry of a redox active film tethered to metallic leads and immersed in electrolyte. The methodology is centred on aligning the lifetime of the process of electron exchange with associated resistance and capacitance quantities. Notably, however, these are no longer those empirically known as charge transfer resistance and pseudo-capacitance, but are those derived instead from a consideration of the quantum states contained in molecular films and their accessibility through a scattering region existing between them and the metallic probe. The averaged lifetime (τr) associated with the redox site occupancy is specifically dependent on scattering associated with the quantum channels linking them to the underlying metallic continuum and associated with both a quantum resistance (Rq) and an electrochemical (redox) capacitance (Cr). These are related to electron transfer rate through k = 1/τr = (RqCr)−1. The proposed mesoscopic approach is consistent with Marcus’s (electron transfer rate) theory and experimental measurements obtained by capacitance spectroscopy. PMID:26757677

  20. Video and HTML: Testing Online Tutorial Formats with Biology Students

    ERIC Educational Resources Information Center

    Craig, Cindy L.; Friehs, Curt G.

    2013-01-01

    This study compared two common types of online information literacy tutorials: a streaming media tutorial using animation and narration and a text-based tutorial with static images. Nine sections of an undergraduate biology lab class (234 students total) were instructed by a librarian on how to use the BIOSIS Previews database. Three sections…

  1. Should soil testing services measure soil biological activity?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Health of agricultural soils depends largely on conservation management to promote soil organic C accumulation. Total soil organic C changes slowly, but active fractions are more dynamic. A key indicator of healthy soil is potential biological activity, which could be measured rapidly with soil te...

  2. Persisting Misconceptions: Using Pre- and Post-Tests to Identify Biological Misconceptions.

    ERIC Educational Resources Information Center

    Nazario, Gladys M.; Burrowes, Patricia A.; Rodriguez, Julio

    2002-01-01

    Explains a research project conducted at the University of Puerto Rico among students taking biology to develop and test a constructivist learning environment and identify students' misconceptions in biology. Lists the questions on which students showed misconceptions during the pre- and post-tests. (Contains 27 references.) (YDS)

  3. Universality of Mesoscopic Fluctuations for Orthogonal Polynomial Ensembles

    NASA Astrophysics Data System (ADS)

    Breuer, Jonathan; Duits, Maurice

    2016-03-01

    We prove that the fluctuations of mesoscopic linear statistics for orthogonal polynomial ensembles are universal in the sense that two measures with asymptotic recurrence coefficients have the same asymptotic mesoscopic fluctuations (under an additional assumption on the local regularity of one of the measures). The convergence rate of the recurrence coefficients determines the range of scales on which the limiting fluctuations are identical. Our main tool is an analysis of the Green's function for the associated Jacobi matrices.As a particular consequencewe obtain a central limit theorem for the modified Jacobi Unitary Ensembles on all mesoscopic scales.

  4. Mesoscopic magnetism and superconductivity: recent perspectives.

    SciTech Connect

    Basaran, Ali C.; Villegas, Javier E.; Jiang, J. S.; Hoffmann, Axel; Schuller, Ivan K.

    2015-11-01

    Mesoscopic Superconductivity and Magnetism at intermediate (“Mesoscopic”) length scales between atomic and bulk, have a long history of interesting new science. The existence of multiple length scales allows for the development of new science when different length scales become comparable to relevant geometric sizes. Different new phenomena appear due to topological interactions, geometric confinement, proximity between dissimilar materials, dimensional crossover, and collective effects induced by the periodicity. In this brief review we are not able to cover comprehensively this vast field. Instead we select a few recent exciting highlights, which illustrate the type of novel science which can be accomplished in superconducting and magnetic structures. Superconductors and magnetic materials can serve as model systems and provide new ideas, which can be extended to other systems such as ferroelectrics and multiferroics. In this paper we also highlight general open questions and new directions in which the field may move.

  5. Mesoscopic and continuum modelling of angiogenesis.

    PubMed

    Spill, F; Guerrero, P; Alarcon, T; Maini, P K; Byrne, H M

    2015-02-01

    Angiogenesis is the formation of new blood vessels from pre-existing ones in response to chemical signals secreted by, for example, a wound or a tumour. In this paper, we propose a mesoscopic lattice-based model of angiogenesis, in which processes that include proliferation and cell movement are considered as stochastic events. By studying the dependence of the model on the lattice spacing and the number of cells involved, we are able to derive the deterministic continuum limit of our equations and compare it to similar existing models of angiogenesis. We further identify conditions under which the use of continuum models is justified, and others for which stochastic or discrete effects dominate. We also compare different stochastic models for the movement of endothelial tip cells which have the same macroscopic, deterministic behaviour, but lead to markedly different behaviour in terms of production of new vessel cells. PMID:24615007

  6. Paramagnetic supercurrent in a mesoscopic superconducting disk

    NASA Astrophysics Data System (ADS)

    Kanda, Akinobu; Ootuka, Youiti

    2003-05-01

    We report an experimental evidence for the paramagnetic supercurrent flowing along the periphery of a mesoscopic superconducting disk in decreasing perpendicular magnetic fields. The sample is an Al superconducting disk with a thin drain lead. Several Cu leads are connected to different parts of the ring periphery through highly resistive tunnel junctions. From voltage drop across a tunnel junction, we study the change in the local superconducting energy gap as a function of perpendicular magnetic field. We find that the energy gap at the ring periphery decreases with decreasing the magnetic field, showing that the circulating supercurrent is in the direction supporting the external magnetic field ( paramagnetic). The condition for the observation is the same as that for the paramagnetic Meissner effect (Geim et al., Nature 390 (1997) 259), implying that the origin of the paramagnetic Meissner effect is the paramagnetic supercurrent.

  7. Giant vortex state in mesoscopic superconductors

    NASA Astrophysics Data System (ADS)

    Cobacy García, Luis; Giraldo, Jairo

    2005-08-01

    Using the self-consistent solution of the nonlinear Ginzburg-Landau equations, the superconducting state of a type II mesoscopic cylinder and of an infinite thin sheet with a circular hole (antidot), in the presence of an homogeneous magnetic field is studied. Close to the third critical field, the magnetic field penetrates the sample in the form of a vortex around the axis of the cylinder or of the antidot. This result has been found previously by other authors. The vortex, called a giant vortex, can carry several flux quanta. The giant vortex is persistent when the state is metastable and evolves to the so called paramagnetic Meissner effect (PME) within the cylinder. The behaviour of this effect as a function of the Ginzburg-Landau (GL) parameter is studied and the results are discussed. Gibbs free energy, order parameter and magnetic induccion as a function of the applied field and of the GL parameter are also studied.

  8. Mesoscopic rings with spin-orbit interactions

    NASA Astrophysics Data System (ADS)

    Berche, Bertrand; Chatelain, Christophe; Medina, Ernesto

    2010-09-01

    A didactic description of charge and spin equilibrium currents on mesoscopic rings in the presence of spin-orbit interaction is presented. Emphasis is made on the non-trivial construction of the correct Hamiltonian in polar coordinates, the calculation of eigenvalues and eigenfunctions and the symmetries of the ground-state properties. Spin currents are derived following an intuitive definition, and then a more thorough derivation is built upon the canonical Lagrangian formulation that emphasizes the SU(2) gauge structure of the transport problem of spin-1/2 fermions in spin-orbit active media. The quantization conditions that follow from the constraint of single-valued Pauli spinors are also discussed. The targeted students are those of a graduate condensed matter physics course.

  9. Equilibrium and shot noise in mesoscopic systems

    SciTech Connect

    Martin, T.

    1994-10-01

    Within the last decade, there has been a resurgence of interest in the study of noise in Mesoscopic devices, both experimentally and theoretically. Noise in solid state devices can have different origins: there is 1/f noise, which is believed to arise from fluctuations in the resistance of the sample due to the motion of impurities. On top of this contribution is a frequency independent component associated with the stochastic nature of electron transport, which will be the focus of this paper. If the sample considered is small enough that dephasing and inelastic effects can be neglected, equilibrium (thermal) and excess noise can be completely described in terms of the elastic scattering properties of the sample. As mentioned above, noise arises as a consequence of random processes governing the transport of electrons. Here, there are two sources of randomness: first, electrons incident on the sample occupy a given energy state with a probability given by the Fermi-Dirac distribution function. Secondly, electrons can be transmitted across the sample or reflected in the same reservoir where they came from with a probability given by the quantum mechanical transmission/reflection coefficients. Equilibrium noise refers to the case where no bias voltage is applied between the leads connected to the sample, where thermal agitation alone allows the electrons close to the Fermi level to tunnel through the sample. In general, equilibrium noise is related to the conductance of the sample via the Johnson-Nyquist formula. In the presence of a bias, in the classical regime, one expects to recover the full shot noise < {Delta}{sup 2}I >= 2I{Delta}{mu} as was observed a long time ago in vacuum diodes. In the Mesoscopic regime, however, excess noise is reduced below the shot noise level. The author introduces a more intuitive picture, where the current passing through the device is a superposition of pulses, or electron wave packets, which can be transmitted or reflected.

  10. LASER BIOLOGY: Optomechanical tests of hydrated biological tissues subjected to laser shaping

    NASA Astrophysics Data System (ADS)

    Omel'chenko, A. I.; Sobol', E. N.

    2008-03-01

    The mechanical properties of a matrix are studied upon changing the size and shape of biological tissues during dehydration caused by weak laser-induced heating. The cartilage deformation, dehydration dynamics, and hydraulic conductivity are measured upon laser heating. The hydrated state and the shape of samples of separated fascias and cartilaginous tissues were controlled by using computer-aided processing of tissue images in polarised light.

  11. Testing systems for biologic markers of genotoxic exposure and effect

    SciTech Connect

    Mendelsohn, M.L.

    1986-11-19

    Societal interest in genotoxicity stems from two concerns: the fear of carcinogenesis secondary to somatic mutation; and the fear of birth defects and decreasing genetic fitness secondary to heritable mutation. There is a pressing need to identify agents that can cause these effects, to understand the underlying dose-response relationships, to identify exposed populations, and to estimate both the magnitude of exposure and the risk of adverse health effects in such populations. Biologic markers refer either to evidence in surrogate organisms, or to the expressions of exposure and effect in human populations. 21 refs.

  12. Broken detailed balance at mesoscopic scales in active biological systems.

    PubMed

    Battle, Christopher; Broedersz, Chase P; Fakhri, Nikta; Geyer, Veikko F; Howard, Jonathon; Schmidt, Christoph F; MacKintosh, Fred C

    2016-04-29

    Systems in thermodynamic equilibrium are not only characterized by time-independent macroscopic properties, but also satisfy the principle of detailed balance in the transitions between microscopic configurations. Living systems function out of equilibrium and are characterized by directed fluxes through chemical states, which violate detailed balance at the molecular scale. Here we introduce a method to probe for broken detailed balance and demonstrate how such nonequilibrium dynamics are manifest at the mesosopic scale. The periodic beating of an isolated flagellum from Chlamydomonas reinhardtii exhibits probability flux in the phase space of shapes. With a model, we show how the breaking of detailed balance can also be quantified in stationary, nonequilibrium stochastic systems in the absence of periodic motion. We further demonstrate such broken detailed balance in the nonperiodic fluctuations of primary cilia of epithelial cells. Our analysis provides a general tool to identify nonequilibrium dynamics in cells and tissues. PMID:27126047

  13. Biologically Relevant Exposure Science for 21st Century Toxicity Testing

    EPA Science Inventory

    High visibility efforts in toxicity testing and computational toxicology including the recent NRC report, Toxicity Testing in the 21st Century: a Vision and Strategy (NRC, 2007), raise important research questions and opportunities for the field of exposure science. The authors ...

  14. Emerging measurement techniques for studies of mesoscopic superconductors.

    SciTech Connect

    Rydh, A.; Tagliati, S.; Nilsson, R. A.; Xie, R.; Pearson, J. E.; Welp, U.; Kwok, W. K.; Divan, R.

    2008-01-01

    Experimental research on mesoscopic systems puts high demands on the measurement infrastructure, including measurement system with associated sample preparation, experimental design, measurement electronics, and data collection. Successful experiments require both the ability to manufacture small samples and to successfully and accurately study their novel properties. Here, we discuss some aspects and recent advancements of general measurement techniques that should benefit several characterization methods such as thermodynamic, magnetic, and transport studies of mesoscopic superconductors.

  15. Reaction times to weak test lights. [psychophysics biological model

    NASA Technical Reports Server (NTRS)

    Wandell, B. A.; Ahumada, P.; Welsh, D.

    1984-01-01

    Maloney and Wandell (1984) describe a model of the response of a single visual channel to weak test lights. The initial channel response is a linearly filtered version of the stimulus. The filter output is randomly sampled over time. Each time a sample occurs there is some probability increasing with the magnitude of the sampled response - that a discrete detection event is generated. Maloney and Wandell derive the statistics of the detection events. In this paper a test is conducted of the hypothesis that the reaction time responses to the presence of a weak test light are initiated at the first detection event. This makes it possible to extend the application of the model to lights that are slightly above threshold, but still within the linear operating range of the visual system. A parameter-free prediction of the model proposed by Maloney and Wandell for lights detected by this statistic is tested. The data are in agreement with the prediction.

  16. IERL-RTP PROCEDURES MANUAL: LEVEL 1 ENVIRONMENTAL ASSESSMENT BIOLOGICAL TESTS

    EPA Science Inventory

    The manual gives revised procedures for Level 1 environmental assessment biological tests, and supersedes the first edition, EPA-600/7-77-043 (NTIS No. PB 268484), published in April 1977. The revised biological procedures complement the Level 1 chemical and physical procedures p...

  17. Expertise for Teaching Biology Situated in the Context of Genetic Testing

    ERIC Educational Resources Information Center

    van der Zande, Paul; Akkerman, Sanne F.; Brekelmans, Mieke; Waarlo, Arend Jan; Vermunt, Jan D.

    2012-01-01

    Contemporary genomics research will impact the daily practice of biology teachers who want to teach up-to-date genetics in secondary education. This article reports on a research project aimed at enhancing biology teachers' expertise for teaching genetics situated in the context of genetic testing. The increasing body of scientific knowledge…

  18. A Knowledge Base for Teaching Biology Situated in the Context of Genetic Testing

    ERIC Educational Resources Information Center

    van der Zande, Paul; Waarlo, Arend Jan; Brekelmans, Mieke; Akkerman, Sanne F.; Vermunt, Jan D.

    2011-01-01

    Recent developments in the field of genomics will impact the daily practice of biology teachers who teach genetics in secondary education. This study reports on the first results of a research project aimed at enhancing biology teacher knowledge for teaching genetics in the context of genetic testing. The increasing body of scientific knowledge…

  19. Australian Biology Test Item Bank, Years 11 and 12. Volume II: Year 12.

    ERIC Educational Resources Information Center

    Brown, David W., Ed.; Sewell, Jeffrey J., Ed.

    This document consists of test items which are applicable to biology courses throughout Australia (irrespective of course materials used); assess key concepts within course statement (for both core and optional studies); assess a wide range of cognitive processes; and are relevant to current biological concepts. These items are arranged under…

  20. Field test of a biological assumption of instream flow models

    SciTech Connect

    Cada, G.F.; Sale, M.J.; Cushman, R.M.; Loar, J.M.

    1983-01-01

    Hydraulic-rating methods are an attractive means of deriving instream flow recommendations at many small hydropower sites because they represent a compromise between relatively inexpensive, low-resolution, discharge methods and the costly, complex, habitat evaluation models. Like the other methods, however, they rely on certain biological assumptions about the relationship between aquatic biota and streamflow characteristics. One such assumption is that benthic production available as food for fishes is proportional to stream bottom area. Wetted perimeter is an easily measured physical parameter which represents bottom area and that is a function of discharge. Therefore, wetted perimeter should reflect the benthic food resource available to support stream fishes under varying flows. As part of a larger effort to compare a number of existing instream flow assessment methods in southern Appalachian trout streams, we examined the validity of the benthos/wetted perimeter relationship at four field sites. Benthos samples were taken at permanent riffle transects over a variety of discharges and were used to relate observed benthos densities to the fluctuations in wetted perimeter and streamflow in these systems. For most of the sites and taxa examined, benthic densities did not show a consistent relationship with discharge/wetted perimeter dynamics. Our analysis indicates that simple physical habitat descriptors obtained from hydraulic-rating models do not provide sufficient information on the response of benthic organisms to decreased discharges. Consequently, these methods may not be sufficient to protect aquatic resources in water-use conflicts.

  1. Cosmo Cassette: A Microfluidic Microgravity Microbial System For Synthetic Biology Unit Tests and Satellite Missions

    NASA Technical Reports Server (NTRS)

    Berliner, Aaron J.

    2013-01-01

    Although methods in the design-build-test life cycle of the synthetic biology field have grown rapidly, the expansion has been non-uniform. The design and build stages in development have seen innovations in the form of biological CAD and more efficient means for building DNA, RNA, and other biological constructs. The testing phase of the cycle remains in need of innovation. Presented will be both a theoretical abstraction of biological measurement and a practical demonstration of a microfluidics-based platform for characterizing synthetic biological phenomena. Such a platform demonstrates a design of additive manufacturing (3D printing) for construction of a microbial fuel cell (MFC) to be used in experiments carried out in space. First, the biocompatibility of the polypropylene chassis will be demonstrated. The novel MFCs will be cheaper, and faster to make and iterate through designs. The novel design will contain a manifold switchingdistribution system and an integrated in-chip set of reagent reservoirs fabricated via 3D printing. The automated nature of the 3D printing yields itself to higher resolution switching valves and leads to smaller sized payloads, lower cost, reduced power and a standardized platform for synthetic biology unit tests on Earth and in space. It will be demonstrated that the application of unit testing in synthetic biology will lead to the automatic construction and validation of desired constructs. Unit testing methodologies offer benefits of preemptive problem identification, change of facility, simplicity of integration, ease of documentation, and separation of interface from implementation, and automated design.

  2. VALIDITY OF EFFLUENT AND AMBIENT TOXICITY TESTS FOR PREDICTING BIOLOGICAL IMPACT, BACK RIVER, BALTIMORE HARBOR, MARYLAND

    EPA Science Inventory

    The purpose for the study was to measure the toxicity of effluents discharged to an estuary using freshwater test species and compare the predictions with the receiving water biological impact. In addition, ambient tests were done in conjunction with salinity tolerance tests to c...

  3. IERL-RTP PROCEDURES MANUAL: LEVEL 1. ENVIRONMENTAL ASSESSMENT BIOLOGICAL TESTS FOR PILOT STUDIES

    EPA Science Inventory

    The manual gives Level 1 biological testing procedures (recommended by Industrial Environmental Research Laboratory--Research Triangle Park) for personnel experienced in conducting bioassays on samples from industrial and energy producing processes. The phased environmental asses...

  4. Memory effects and mesoscopic quantum transport

    NASA Astrophysics Data System (ADS)

    Knezevic, Irena

    The active region of a mesoscopic structure or a modern semiconductor device needs to be treated as a dynamically open many-body system, exchanging information and particles with the contacts. The feedback from the active region to the contacts cannot be neglected, especially during the transient regime, because, due to the small size, both the active region and the contacts contain a small number of electrons. In this work, a rigorous theoretical approach for treating mesoscopic electronic systems as open many-body systems is developed. It is based on the partial-trace-free (PTF) approach that has provided a new outlook on the evolution of the reduced density matrix of an open system, and enabled several lines of research, which are presented in this work. First, an effective, memory-containing interaction was recognized in the equations of motion for the representation submatrices of the evolution operator (these submatrices are written in a special basis, adapted for the PTF approach, in the Liouville space of the composite closed system). The memory dressing, a quantity that separates the effective from the physical interaction, was identified. It obeys a self-contained nonlinear equation of motion (the Riccati matrix equation), whose solution can be represented in a diagrammatic fashion and enables physical approximations beyond the weak coupling limit. On the other hand, a foundation for the generalization of nonequilibrium Green's functions to open systems was laid. Two-time correlation functions were generalized, and evolution in both the transient and the steady-state regime was discussed. Based on the PTF approach, a second-order master equation of motion was derived for the reduced density matrix of the active region of a real electronic system: a resonant-tunneling diode (RTD). This equation incorporates the exchange of information and particles between the active region and the contacts, while being computationally tractable. The master equation was

  5. Method of testing very soft biological tissues in compression.

    PubMed

    Miller, Karol

    2005-01-01

    Mechanical properties of very soft tissues, such as brain, liver, kidney and prostate have recently joined the mainstream research topics in biomechanics. This has happened in spite of the fact that these tissues do not bear mechanical loads. The interest in the biomechanics of very soft tissues has been motivated by the developments in computer-integrated and robot-aided surgery--in particular, the emergence of automatic surgical tools and robots-as well as advances in virtual reality techniques. Mechanical testing of very soft tissues provides a formidable challenge for an experimenter. Very soft tissues are usually tested in compression using an unconfined compression set-up, which requires ascertaining that friction between sample faces and stress-strain machine platens is close to zero. In this paper a more reliable method of testing is proposed. In the proposed method top and bottom faces of a cylindrical specimen with low aspect ratio are rigidly attached to the platens of the stress-strain machine (e.g. using surgical glue). This arrangement allows using a no-slip boundary condition in the analysis of the results. Even though the state of deformation in the sample cannot be treated as orthogonal the relationships between total change of height (measured) and strain are obtained. Two important results are derived: (i) deformed shape of a cylindrical sample subjected to uniaxial compression is independent on the form of constitutive law, (ii) vertical extension in the plane of symmetry lambda(z) is proportional to the total change of height for strains as large as 30%. The importance and relevance of these results to testing procedures in biomechanics are highlighted. PMID:15519351

  6. Modeling the Drug Discovery Process: The Isolation and Biological Testing of Eugenol from Clove Oil

    NASA Astrophysics Data System (ADS)

    Miles, William H.; Smiley, Patricia M.

    2002-01-01

    This experiment describes the isolation and biological testing of eugenol and neutral compounds from commercially available clove oil. By coupling the chemical separation of the components of clove oil (an experiment described in many introductory organic laboratory textbooks) with a simple antibiotic test, the students "discover" the biologically active compound in clove oil. This experiment models one of the primary methods used in the discovery of new pharmaceutical agents.

  7. Quantum Mesoscopic Physics of Electrons and Photons

    NASA Astrophysics Data System (ADS)

    Akkermans, Eric

    2013-03-01

    We first review basic notions of coherent quantum transport at the mesoscopic scale for both electronic and photonic systems. We then show that successful descriptions developed for coherent electronic transport (e.g. weak localization and UCF) and thermodynamics (persistent currents), noise and full counting statistics can be extended and applied to the study of Quantum Electrodynamics of quantum conductors and of quantum optics based on photons emitted by such conductors. In this context, we discuss the two following specific problems : (1) Ramsey fringes and time domain interference for particle creation form a quantum vacuum with a specific application to dynamical Coulomb blockade. In that setup, the current noise of a coherent conductor is biased by two successive voltage pulses. An interference pattern between photon assisted processes is observed which is explained by the contribution of several processes to the probability to emit photons after each pulse. Recent experiments in this context will be discussed. (2) Quantum emitter coupled to a fractal environment. A new and unexpected type of oscillatory structures for the probability of spontaneous emission has been obtained which results from the fractal nature of the quantum vacuum. When applied to the case of a tunnel junction as a quantum emitter of photons, the same oscillatory structure arises for the conductance of the tunnel junction. This work was supported by the Israel Science Foundation Grant No.924/09

  8. Mesoscopic quantum multiplex for channeling bunches

    NASA Astrophysics Data System (ADS)

    Shen, Jing

    1998-09-01

    (1) Bogacz-Cline channeling is an interesting idea that can transform a bunch of low particle intensity to a collider of high luminosity but it was maintained as impossible to carry out because of three technical problems. (2) The first of which is discussed in this paper, and it is how to get billions particles from each bunch to enter into and channel through a single crystal channel. (3) Two basic difficulties of entrance are discussed in this paper. The first is due to the Heisenberg's uncertainty, and the second is the dimension reduction of a beam bunch in crystal from 3D to 1D. (4) To overcome these difficulties, a hybrid device named Mesoscopic Quantum Multiplex (MQM) is designed to achieve entrance and channeling. It is a quantum generalization of classical multiplex in detector readout electronics for the classical-quantum interface. It is made by nano-crystalline technology. (5) The MQM can channel the Richter-Kimura-Takada flat e± beams of NLC-JLC, and low emittance p or heavy ion beams as well as the Bogacz-Cline μ± beams, and the Nagamine-Chu cool μ± beams.

  9. Mesoscopic hydrothermodynamics of complex-structured materials

    NASA Astrophysics Data System (ADS)

    Vasconcellos, Áurea R.; Silva, A. A. P.; Luzzi, Roberto; Casas-Vázquez, J.; Jou, David

    2013-10-01

    Some experimental results in the study of disordered systems, polymeric fluids, solutions of micelles and surfactants, ionic-glass conductors, and others show a hydrodynamic behavior labeled “anomalous” with properties described by some kind of fractional power laws in place of the standard ones. This is a consequence of the fractal-like structure that is present in these systems of which we do not have a detailed description, thus impairing the application of the conventional ensemble formalism of statistical mechanics. In order to obtain a physical picture of the phenomenon for making predictions which may help with technological and industrial decisions, one may resort to different styles (so-called nonconventional) in statistical mechanics. In that way can be introduced a theory for handling such impaired situations, a nonconventional mesoscopic hydrothermodynamics (MHT). We illustrate the question presenting an application in a contracted description of such nonconventional MHT, consisting in the use of the Renyi approach to derive a set of coupled nonstandard evolution equations, one for the density, a nonconventional Maxwell-Cattaneo equation, which in a limiting case goes over a non-Fickian diffusion equation, and other for the velocity in fluids under forced flow. For illustration the theory is applied to the study of the hydrodynamic motion in several soft-matter systems under several conditions such as streaming flow appearing in electrophoretic techniques and flow generated by harmonic forces arising in optical traps. The equivalence with Lévy processes is discussed and comparison with experiment is done.

  10. Mesoscopic magnetomechanical hysteresis in a magnetorheological elastomer

    NASA Astrophysics Data System (ADS)

    Biller, A. M.; Stolbov, O. V.; Raikher, Yu. L.

    2015-08-01

    Field-induced magnetostatic interaction in a pair of identical particles made of a magnetically soft ferromagnet is studied. It is shown that due to saturation of the ferromagnet magnetization, this case differs significantly from the (super)paramagnetic one. A numerical solution is given, discussed, and compared with that provided by a simpler model (nonlinear mutual dipoles). We show that for multidomain ferromagnetic particles embedded in an elastomer matrix, as for paramagnetic ones in the same environment, pair clusters may form or break by a hysteresis scenario. However, the magnetization saturation brings in important features to this effect. First, the bistability state and the hysteresis take place only in a limited region of the material parameters of the system. Second, along with the hysteresis jumps occurring under the sole influence of the field, the "latent" hysteresis is possible which realizes only if the action of the field is combined with some additional (nonmagnetic) external factor. The obtained conditions, when used to assess the possibility of clustering in real magnetorheological polymers, infer an important role of mesoscopic magnetomechanical hysteresis for the macroscopic properties of these composites.

  11. Chylomicrons: Advances in biology, pathology, laboratory testing, and therapeutics.

    PubMed

    Julve, Josep; Martín-Campos, Jesús M; Escolà-Gil, Joan Carles; Blanco-Vaca, Francisco

    2016-04-01

    The adequate absorption of lipids is essential for all mammalian species due to their inability to synthesize some essential fatty acids and fat-soluble vitamins. Chylomicrons (CMs) are large, triglyceride-rich lipoproteins that are produced in intestinal enterocytes in response to fat ingestion, which function to transport the ingested lipids to different tissues. In addition to the contribution of CMs to postprandial lipemia, their remnants, the degradation products following lipolysis by lipoprotein lipase, are linked to cardiovascular disease. In this review, we will focus on the structure-function and metabolism of CMs. Second, we will analyze the impact of gene defects reported to affect CM metabolism and, also, the role of CMs in other pathologies, such as atherothrombotic cardiovascular disease and diabetes mellitus. Third, we will provide an overview of the laboratory tests currently used to study CM disorders, and, finally, we will highlight current treatments in diseases affecting CMs. PMID:26868089

  12. Dormancy and Recovery Testing for Biological Wastewater Processors

    NASA Technical Reports Server (NTRS)

    Hummerick, Mary E.; Coutts, Janelle L.; Lunn, Griffin M.; Spencer, LaShelle; Khodadad, Christina L.; Birmele, Michele N.; Frances, Someliz; Wheeler, Raymond

    2015-01-01

    Bioreactors, such as the aerated hollow fiber membrane type, have been proposed and studied for a number of years as an alternate approach for treating wastewater streams for space exploration. Several challenges remain to be resolved before these types of bioreactors can be used in space settings, including transporting the bioreactors with intact and active biofilms, whether that be to the International Space Station or beyond, or procedures for safing the systems and placing them into a dormant state for later start-up. Little information is available on such operations as it is not common practice for terrestrial systems. This study explored several dormancy processes for established bioreactors to determine optimal storage and recovery conditions. Procedures focused on complete isolation of the microbial communities from an operational standpoint and observing the effects of: 1) storage temperature, and 2) storage with or without the reactor bulk fluid. The first consideration was tested from a microbial integrity and power consumption standpoint; both ambient temperature (25 C) and cold (4 C) storage conditions were studied. The second consideration was explored; again, for microbial integrity as well as plausible real-world scenarios of how terrestrially established bioreactors would be transported to microgravity and stored for periods of time between operations. Biofilms were stored without the reactor bulk fluid to simulate transport of established biofilms into microgravity, while biofilms stored with the reactor bulk fluid simulated the most simplistic storage condition to implement operations for extended periods of nonuse. Dormancy condition did not have an influence on recovery in initial studies with immature biofilms (48 days old), however a lengthy recovery time was required (20+ days). Bioreactors with fully established biofilms (13 months) were able to recover from a 7-month dormancy period to steady state operation within 4 days (approx. 1

  13. Dormancy and Recovery Testing for Biological Wastewater Processors

    NASA Technical Reports Server (NTRS)

    Hummerick, Mary E.; Coutts, Janelle L.; Lunn, Griffin M.; Spencer, LaShelle; Khodadad, Christina L.; Frances, Someliz; Wheller, Raymond

    2015-01-01

    Bioreactors, such as aerated membrane type bioreactors have been proposed and studied for a number of years as an alternate approach for treating wastewater streams for space exploration. Several challenges remain before these types of bioreactors can be used in space settings, including transporting the bioreactors with their microbial communities to space, whether that be the International Space Station or beyond, or procedures for safing the systems and placing them into dormant state for later start-up. Little information is available on such operations as it is not common practice for terrestrial systems. This study explored several dormancy processes for established bioreactors to determine optimal storage and recovery conditions. Procedures focused on complete isolation of the microbial communities from an operational standpoint and observing the effects of: 1) storage temperature, and 2) storage with or without the reactor bulk fluid. The first consideration was tested from a microbial integrity and power consumption standpoint; both room temperature (25 C) and cold (4 C) storage conditions were studied. The second consideration was explored; again, for microbial integrity as well as plausible real-world scenarios of how terrestrially established bioreactors would be transported to microgravity and stored for periods of time between operations. Biofilms were stored without the reactor bulk fluid to simulate transport of established biofilms into microgravity, while biofilms stored with the reactor bulk fluid simulated the most simplistic storage condition to implement operations for extended periods of nonuse. Dormancy condition did not have an influence on recovery in initial studies with immature biofilms (48 days old), however, a lengthy recovery time was required (20+ days). Bioreactors with fully established biofilms (13 months) were able to recover from a 7-month dormancy period to steady state operation within 4 days (approximately 1 residence cycle

  14. High-frequency search for mass-coupled mesoscopic forces

    NASA Astrophysics Data System (ADS)

    Yan, Haiyang; Otto, Hans; Weisman, Evan; Khatiwada, Rakshya; Long, Josh

    2014-03-01

    The possible existence of unobserved interactions of nature with ranges of mesoscopic scale (microns to millimeters) and very weak couplings to matter has attracted a great deal of scientific attention. We report on an experimental search for exotic mass-coupled in this range. Our technique uses a planar, double-torsional tungsten oscillator as a test mass, a similar oscillator as a source mass, and a stiff conducting shield in between them to suppress backgrounds. This method affords operation at the limit of instrumental thermal noise, which we have we have recently demonstrated with a measurement of the noise kinetic energy of a detector prototype in thermal equilibrium at room temperature. The fluctuations of the oscillator in a high-Q torsional mode with a resonant frequency near 1 kHz are detected with capacitive transducers coupled to a sensitive differential amplifier. The apparatus is calibrated by means of a known electrostatic force and input from a finite-element model of the selected mode. The measured kinetic energy is in agreement with the expected value of 1/2 kT.

  15. Using biological data to test climate change refugia

    NASA Astrophysics Data System (ADS)

    Morelli, T. L.; Maher, S. P.

    2015-12-01

    The concept of refugia has been discussed from theoretical and paleontological perspectives to address how populations persisted during periods of unfavorable climate. Recently, several studies have applied the idea to contemporary landscapes to identify locations that are buffered from climate change effects so as to favor greater persistence of valued resources relative to other areas. Refugia are now being discussed among natural resource agencies as a potential adaptation option in the face of anthropogenic climate change. Using downscaled climate data, we identified hypothetical refugial meadows in the Sierra Nevada and then tested them using survey and genetic data from Belding's ground squirrel (Urocitellus beldingi) populations. We predicted that refugial meadows would show higher genetic diversity, higher rates of occupancy and lower rates of extirpation over time. At each step of the research, we worked with managers to ensure the largest impact. Although no panacea, identifying climate change refugia could be an important strategy for prioritizing habitats for management intervention in order to conserve populations. This research was supported by the California LCC, the Northeast Climate Science Center, and NSF.

  16. 40 CFR 230.61 - Chemical, biological, and physical evaluation and testing.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 26 2013-07-01 2013-07-01 false Chemical, biological, and physical evaluation and testing. 230.61 Section 230.61 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) OCEAN DUMPING SECTION 404(b)(1) GUIDELINES FOR SPECIFICATION OF DISPOSAL SITES FOR DREDGED OR FILL MATERIAL Evaluation and Testing...

  17. 40 CFR 230.61 - Chemical, biological, and physical evaluation and testing.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 25 2014-07-01 2014-07-01 false Chemical, biological, and physical evaluation and testing. 230.61 Section 230.61 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) OCEAN DUMPING SECTION 404(b)(1) GUIDELINES FOR SPECIFICATION OF DISPOSAL SITES FOR DREDGED OR FILL MATERIAL Evaluation and Testing...

  18. 40 CFR 230.61 - Chemical, biological, and physical evaluation and testing.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 25 2011-07-01 2011-07-01 false Chemical, biological, and physical evaluation and testing. 230.61 Section 230.61 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) OCEAN DUMPING SECTION 404(b)(1) GUIDELINES FOR SPECIFICATION OF DISPOSAL SITES FOR DREDGED OR FILL MATERIAL Evaluation and Testing...

  19. Effects of Scoring by Section and Independent Scorers' Patterns on Scorer Reliability in Biology Essay Tests

    ERIC Educational Resources Information Center

    Ebuoh, Casmir N.; Ezeudu, S. A.

    2015-01-01

    The study investigated the effects of scoring by section, use of independent scorers and conventional patterns on scorer reliability in Biology essay tests. It was revealed from literature review that conventional pattern of scoring all items at a time in essay tests had been criticized for not being reliable. The study was true experimental study…

  20. A Computer-Aided Self-Testing System for Biological Psychology.

    ERIC Educational Resources Information Center

    Leiblum, M. D.; And Others

    1994-01-01

    Describes the production of a computer-aided, self-testing system for university students enrolled in a first-year course in biological psychology. Project aspects described include selection, acquisition and description of software; question banks and test structures; modes of use (computer or printed version); evaluation; and future plans. (11…

  1. Test on the structure of biological sequences via Chaos Game Representation.

    PubMed

    Cénac, Peggy

    2005-01-01

    In this paper biological sequences are modelled by stationary ergodic sequences. A new family of statistical tests to characterize the randomness of the inputs is proposed and analyzed. Tests for independence and for the determination of the appropriate order of a Markov chain are constructed with the Chaos Game Representation (CGR), and applied to several genomes. PMID:16646845

  2. Testing with Feedback Yields Potent, but Piecewise, Learning of History and Biology Facts

    ERIC Educational Resources Information Center

    Pan, Steven C.; Gopal, Arpita; Rickard, Timothy C.

    2016-01-01

    Does correctly answering a test question about a multiterm fact enhance memory for the entire fact? We explored that issue in 4 experiments. Subjects first studied Advanced Placement History or Biology facts. Half of those facts were then restudied, whereas the remainder were tested using "5 W" (i.e., "who, what, when, where",…

  3. Collaborative Testing Improves Performance but Not Content Retention in a Large-Enrollment Introductory Biology Class

    ERIC Educational Resources Information Center

    Leight, Hayley; Saunders, Cheston; Calkins, Robin; Withers, Michelle

    2012-01-01

    Collaborative testing has been shown to improve performance but not always content retention. In this study, we investigated whether collaborative testing could improve both performance and content retention in a large, introductory biology course. Students were semirandomly divided into two groups based on their performances on exam 1. Each group…

  4. Using Open-Book Tests to Strengthen the Study Skills of Community-College Biology Students

    ERIC Educational Resources Information Center

    Phillips, Gregory

    2006-01-01

    The author observed that students enrolled in first-year college biology courses often had weak study skills. This longitudinal study examined the use of open-book tests to encourage reading and to assess the improvement of college students' study skills. There was a statistically significant improvement from the initial test to the final test…

  5. Mesoscopic spin Hall effect in semiconductor nanostructures

    NASA Astrophysics Data System (ADS)

    Zarbo, Liviu

    The spin Hall effect (SHE) is a name given to a collection of diverse phenomena which share two principal features: (i) longitudinal electric current flowing through a paramagnetic semiconductor or metallic sample leads to transverse spin current and spin accumulation of opposite sign at opposing lateral edges; (ii) SHE does not require externally applied magnetic field or magnetic ordering in the equilibrium state of the sample, instead it relies on the presence of spin-orbit (SO) couplings within the sample. This thesis elaborates on a new type of phenomenon within the SHE family, predicted in our recent studies [Phys. Rev. B 72, 075361 (2005); Phys. Rev. Lett. 95, 046601 (2005); Phys. Rev. B 72, 075335 (2005); Phys. Rev. B 73 , 075303 (2006); and Europhys. Lett. 77, 47004 (2007)], where pure spin current flows through the transverse electrodes attached to a clean finitesize two-dimensional electron gas (2DEG) due to unpolarized charge current injected through its longitudinal leads. If transverse leads are removed, the effect manifests as nonequilibrium spin Hall accumulation at the lateral edges of 2DEG wires. The SO coupling driving this SHE effect is of the Rashba type, which arises due to structural inversion asymmetry of semiconductor heterostructure hosting the 2DEG. We term the effect "mesoscopic" because the spin Hall currents and accumulations reach optimal value in samples of the size of the spin precession length---the distance over which the spin of an electron precesses by an angle pi. In strongly SO-coupled structures this scale is of the order of ˜100 nm, and, therefore, mesoscopic in the sense of being much larger than the characteristic microscopic scales (such as the Fermi wavelength, screening length, or the mean free path in disordered systems), but still much smaller than the macroscopic ones. Although the first theoretical proposal for SHE, driven by asymmetry in SO-dependent scattering of spin-up and spin-down electrons off impurities

  6. CHAIRMEN'S FOREWORD: The Seventh International Conference on New Phenomena in Mesoscopic Structures & The Fifth International Conference on Surfaces and Interfaces of Mesoscopic Devices

    NASA Astrophysics Data System (ADS)

    Aoyagi, Yoshinobu; Goodnick, Stephen M.

    2006-05-01

    , non-equilibrium transport, instabilities, nano-electro-mechanical systems, mesoscopic Josephson effects, phase coherence and breaking, and the Kondo effect •Systems of nanodevices: Quantum cellular automata, systolic SET processors, quantum neural nets, adaptive effects in circuits, and molecular circuits •Nanomaterials: nanotubes, nanowires, organic and molecular materials, self-assembled nano wires, and organic devices •Nanobioelectronics: electronic properties of biological structures on the nanoscale. This year's conference was organized by Prof Stephen Goodnick, Arizona State University, and Prof Yoshinobu Aoyagi, Tokyo Institute of Technology. The conference benefited from 14 invited speakers, whose topics spanned the above list, and a total of 97 registered attendees. The largest contingent was from Japan, followed closely by the US. In total, there were 49 from Japan, 31 fiom the US, and 17 from Europe. The organizers want to especially thank the sponsors for the meeting: The Office of Naval Research, the Army Research Office, and Arizona State University on the US side, and the Japan Society for the Promotion of Science, through their 151 Committee, on the Japanese side. PROGRAM COMMITTEE •Prof Gerhard Abstreiter, Technical University of Munich •Prof Tsuneya Ando, Tokyo Institute of Technology •Prof John Barker, University of Glasgow •Prof Jonathan Bird, the University at Buffalo •Prof Robert Blick, University of Wisconsin •Prof David Ferry, Chair, Arizona State University •Dr Yoshiro Hirayama, NTT Basic Research Laboratories •Dr Koji Ishibashi, RIKEN •Prof Carlo Jacoboni, University of Modena •Prof David Janes, Purdue University •Prof Friedl Kuchar, University of Leoben •Prof K. Matsumoto, Osaka University •Prof Wolfgang Porod, Notre Dame University •Prof Michiharu Tabe, Shizuoka University •Prof Joachim Wolter, Eindhoven Institute of Technology •Prof Lukas Worschech, University of Würzburg •Dr Naoki Yokoyama, Fujitsu

  7. Mesoscopic Ensembles of Polar Bosons in Triple-Well Potentials

    SciTech Connect

    Lahaye, T.; Pfau, T.; Santos, L.

    2010-04-30

    Mesoscopic dipolar Bose gases in triple-well potentials offer a minimal system for the analysis of the nonlocal character of the dipolar interaction. We show that this nonlocal character may be clearly revealed by a variety of possible ground-state phases. In addition, an appropriate control of short-range and dipolar interactions may lead to novel scenarios for the dynamics of polar bosons in lattices, including the dynamical creation of mesoscopic quantum superpositions, which may be employed in the design of Heisenberg-limited atom interferometers.

  8. Generalized correlation functions for conductance fluctuations and the mesoscopic spin Hall effect

    NASA Astrophysics Data System (ADS)

    Ramos, J. G. G. S.; Barbosa, A. L. R.; Bazeia, D.; Hussein, M. S.; Lewenkopf, C. H.

    2012-12-01

    We study the spin Hall conductance fluctuations in ballistic mesoscopic systems. We obtain universal expressions for the spin and charge current fluctuations, cast in terms of current-current autocorrelation functions. We show that the latter are conveniently parametrized as deformed Lorentzian shape lines, functions of an external applied magnetic field and the Fermi energy. We find that the charge current fluctuations show quite unique statistical features at the symplectic-unitary crossover regime. Our findings are based on an evaluation of the generalized transmission coefficients correlation functions within the stub model and are amenable to experimental test.

  9. Impact of criticism of null-hypothesis significance testing on statistical reporting practices in conservation biology.

    PubMed

    Fidler, Fiona; Burgman, Mark A; Cumming, Geoff; Buttrose, Robert; Thomason, Neil

    2006-10-01

    Over the last decade, criticisms of null-hypothesis significance testing have grown dramatically, and several alternative practices, such as confidence intervals, information theoretic, and Bayesian methods, have been advocated. Have these calls for change had an impact on the statistical reporting practices in conservation biology? In 2000 and 2001, 92% of sampled articles in Conservation Biology and Biological Conservation reported results of null-hypothesis tests. In 2005 this figure dropped to 78%. There were corresponding increases in the use of confidence intervals, information theoretic, and Bayesian techniques. Of those articles reporting null-hypothesis testing--which still easily constitute the majority--very few report statistical power (8%) and many misinterpret statistical nonsignificance as evidence for no effect (63%). Overall, results of our survey show some improvements in statistical practice, but further efforts are clearly required to move the discipline toward improved practices. PMID:17002771

  10. A Knowledge Base for Teaching Biology Situated in the Context of Genetic Testing

    NASA Astrophysics Data System (ADS)

    van der Zande, Paul; Waarlo, Arend Jan; Brekelmans, Mieke; Akkerman, Sanne F.; Vermunt, Jan D.

    2011-10-01

    Recent developments in the field of genomics will impact the daily practice of biology teachers who teach genetics in secondary education. This study reports on the first results of a research project aimed at enhancing biology teacher knowledge for teaching genetics in the context of genetic testing. The increasing body of scientific knowledge concerning genetic testing and the related consequences for decision-making indicate the societal relevance of such a situated learning approach. What content knowledge do biology teachers need for teaching genetics in the personal health context of genetic testing? This study describes the required content knowledge by exploring the educational practice and clinical genetic practices. Nine experienced teachers and 12 respondents representing the clinical genetic practices (clients, medical professionals, and medical ethicists) were interviewed about the biological concepts and ethical, legal, and social aspects (ELSA) of testing they considered relevant to empowering students as future health care clients. The ELSA suggested by the respondents were complemented by suggestions found in the literature on genetic counselling. The findings revealed that the required teacher knowledge consists of multiple layers that are embedded in specific genetic test situations: on the one hand, the knowledge of concepts represented by the curricular framework and some additional concepts (e.g. multifactorial and polygenic disorder) and, on the other hand, more knowledge of ELSA and generic characteristics of genetic test practice (uncertainty, complexity, probability, and morality). Suggestions regarding how to translate these characteristics, concepts, and ELSA into context-based genetics education are discussed.

  11. Establishing construct validity of the Biology I Subject Area Testing program in Mississippi

    NASA Astrophysics Data System (ADS)

    Philippoff, Christy Michelle Hollis

    Science education has undergone many revisions since it was permanently embedded in the country's educational curriculum at the end of the 19th century. Some of these revisions occurred as a direct result of the No Child Left Behind Act (NCLB). This legislation placed more accountability on schools than ever before by requiring that all students pass a series of standardized tests (USDE, 2010). High schools in Mississippi require four areas of standardized testing: English II, Algebra I, U.S. History, and Biology I (Wroten, 2008). The focus of this study is the Biology I Subject Area Test. In an effort to determine the validity of that test, this study explores the importance of the Mississippi Biology I content standards according to the importance ratings and frequency of use ratings by science professionals in Mississippi. The science professionals surveyed for this study were high school science teachers, college science professors and scientists in their professional settings. The science professionals' importance ratings were compared to the importance ratings placed on the content strands by the Mississippi Biology I Subject Area Test. To further determine the test's validity, it is also compared to the National Science Education Standards.

  12. An investigation on impacts of scheduling configurations on Mississippi biology subject area testing

    NASA Astrophysics Data System (ADS)

    Marchette, Frances Lenora

    The purpose of this mixed modal study was to compare the results of Biology Subject Area mean scores of students on a 4 x 4 block schedule, A/B block schedule, and traditional year-long schedule for 1A to 5A size schools. This study also reviewed the data to determine if minority or gender issues might influence the test results. Interviews with administrators and teachers were conducted about the type of schedule configuration they use and the influence that the schedule has on student academic performance on the Biology Subject Area Test. Additionally, this research further explored whether schedule configurations allow sufficient time for students to construct knowledge. This study is important to schools, teachers, and administrators because it can assist them in considering the impacts that different types of class schedules have on student performance and if ethnic or gender issues are influencing testing results. This study used the causal-comparative method for the quantitative portion of the study and constant comparative method for the qualitative portion to explore the relationship of school schedules on student academic achievement on the Mississippi Biology Subject Area Test. The aggregate means of selected student scores indicate that the Mississippi Biology Subject Area Test as a measure of student performance reveals no significant difference on student achievement for the three school schedule configurations. The data were adjusted for initial differences of gender, minority, and school size on the three schedule configurations. The results suggest that schools may employ various schedule configurations and expect student performance on the Mississippi Biology Subject Area Test to be unaffected. However, many areas of concern were identified in the interviews that might impact on school learning environments. These concerns relate to effective classroom management, the active involvement of students in learning, the adequacy of teacher education

  13. Bioinformatics for the synthetic biology of natural products: integrating across the Design-Build-Test cycle.

    PubMed

    Carbonell, Pablo; Currin, Andrew; Jervis, Adrian J; Rattray, Nicholas J W; Swainston, Neil; Yan, Cunyu; Takano, Eriko; Breitling, Rainer

    2016-08-27

    Covering: 2000 to 2016Progress in synthetic biology is enabled by powerful bioinformatics tools allowing the integration of the design, build and test stages of the biological engineering cycle. In this review we illustrate how this integration can be achieved, with a particular focus on natural products discovery and production. Bioinformatics tools for the DESIGN and BUILD stages include tools for the selection, synthesis, assembly and optimization of parts (enzymes and regulatory elements), devices (pathways) and systems (chassis). TEST tools include those for screening, identification and quantification of metabolites for rapid prototyping. The main advantages and limitations of these tools as well as their interoperability capabilities are highlighted. PMID:27185383

  14. Transport dissipative particle dynamics model for mesoscopic advection- diffusion-reaction problems

    SciTech Connect

    Zhen, Li; Yazdani, Alireza; Tartakovsky, Alexandre M.; Karniadakis, George E.

    2015-07-07

    We present a transport dissipative particle dynamics (tDPD) model for simulating mesoscopic problems involving advection-diffusion-reaction (ADR) processes, along with a methodology for implementation of the correct Dirichlet and Neumann boundary conditions in tDPD simulations. tDPD is an extension of the classic DPD framework with extra variables for describing the evolution of concentration fields. The transport of concentration is modeled by a Fickian flux and a random flux between particles, and an analytical formula is proposed to relate the mesoscopic concentration friction to the effective diffusion coefficient. To validate the present tDPD model and the boundary conditions, we perform three tDPD simulations of one-dimensional diffusion with different boundary conditions, and the results show excellent agreement with the theoretical solutions. We also performed two-dimensional simulations of ADR systems and the tDPD simulations agree well with the results obtained by the spectral element method. Finally, we present an application of the tDPD model to the dynamic process of blood coagulation involving 25 reacting species in order to demonstrate the potential of tDPD in simulating biological dynamics at the mesoscale. We find that the tDPD solution of this comprehensive 25-species coagulation model is only twice as computationally expensive as the DPD simulation of the hydrodynamics only, which is a significant advantage over available continuum solvers.

  15. Mesoscopic structures reveal the network between the layers of multiplex data sets

    NASA Astrophysics Data System (ADS)

    Iacovacci, Jacopo; Wu, Zhihao; Bianconi, Ginestra

    2015-10-01

    Multiplex networks describe a large variety of complex systems, whose elements (nodes) can be connected by different types of interactions forming different layers (networks) of the multiplex. Multiplex networks include social networks, transportation networks, or biological networks in the cell or in the brain. Extracting relevant information from these networks is of crucial importance for solving challenging inference problems and for characterizing the multiplex networks microscopic and mesoscopic structure. Here we propose an information theory method to extract the network between the layers of multiplex data sets, forming a "network of networks." We build an indicator function, based on the entropy of network ensembles, to characterize the mesoscopic similarities between the layers of a multiplex network, and we use clustering techniques to characterize the communities present in this network of networks. We apply the proposed method to study the Multiplex Collaboration Network formed by scientists collaborating on different subjects and publishing in the American Physical Society journals. The analysis of this data set reveals the interplay between the collaboration networks and the organization of knowledge in physics.

  16. Stochastic resonance with a mesoscopic reaction-diffusion system.

    PubMed

    Mahara, Hitoshi; Yamaguchi, Tomohiko; Parmananda, P

    2014-06-01

    In a mesoscopic reaction-diffusion system with an Oregonator reaction model, we show that intrinsic noise can drive a resonant stable pattern in the presence of the initial subthreshold perturbations. Both spatially periodic and aperiodic stochastic resonances are demonstrated by employing the Gillespies stochastic simulation algorithm. The mechanisms for these phenomena are discussed. PMID:25019857

  17. Mesoscopic faults in the Bregaglia (Bergell) massif, Central Alps

    NASA Astrophysics Data System (ADS)

    Passerini, P.; Sguazzoni, G.; Marcucci, M.

    1991-11-01

    The strike, direction of dip and pitch of the striae along mesoscopic faults in the Oligocene granodiorite-tonalite of Val Masino-Val Bregaglia (Bergell) are analysed. Most fault planes are steeply dipping, and show strike-slip or oblique-slip motion. Dominant strikes are NNW or NNE. A relative chronology of fault sets is suggested based on the presence of different minerals (chlorite and epidote) on fault planes. The pattern of mesoscopic faults in the Val Masino-Val Bregaglia massif does not follow the earlier tectonic trends of the Pennidic nappe edifice, nor even the trend of the nearby section of the Insubric Line considered at both regional and mesoscopic scales. The mesoscopic analysis of the Val Masino-Val Bregaglia massif thus reveals a fault system largely oblique to the major Alpine lineaments. The observed fault pattern does not reveal traces of thrusting referable to late Alpine orogenic phases, and can be related to subsequent deformation, dominated by strike-slip movements; this pattern does not match the traditional schemes of extensional dip-slip faulting following orogenesis. It records a stage of tectonic evolution which follows nappe emplacement, yet it precedes vertical or extensional post-orogenic tectonics.

  18. Finite-element methods for spatially resolved mesoscopic electron transport

    NASA Astrophysics Data System (ADS)

    Kramer, Stephan

    2013-09-01

    A finite-element method is presented for calculating the quantum conductance of mesoscopic two-dimensional electron devices of complex geometry attached to semi-infinite leads. For computational purposes, the leads must be cut off at some finite length. To avoid spurious, unphysical reflections, this is modeled by transparent boundary conditions. We introduce the Hardy space infinite-element technique from acoustic scattering as a way of setting up transparent boundary conditions for transport computations spanning the range from the quantum mechanical to the quasiclassical regime. These boundary conditions are exact even for wave packets and thus are especially useful in the limit of high energies with many excited modes. Yet, they possess a memory-friendly sparse matrix representation. In addition to unbounded domains, Hardy space elements allow us to truncate those parts of the computational domain which are irrelevant for the calculation of the transport properties. Thus, the computation can be done only on the region that is essential for a physically meaningful simulation of the scattering states. The benefits of the method are demonstrated by three examples. The convergence properties are tested on the transport through a quasi-one-dimensional quantum wire. It is shown that higher-order finite elements considerably improve current conservation and establish the correct phase shift between the real and the imaginary parts of the electron wave function. The Aharonov-Bohm effect demonstrates that characteristic features of quantum interference can be assessed. A simulation of electron magnetic focusing exemplifies the capability of the computational framework to study the crossover from quantum to quasiclassical behavior.

  19. Sound and Faulty Arguments Generated by Preservice Biology Teachers When Testing Hypotheses Involving Unobservable Entities.

    ERIC Educational Resources Information Center

    Lawson, Anton E.

    2002-01-01

    Investigates the responses of a sample of preservice biology teachers enrolled in a teaching methods course to a casual question about why water rose in a jar inverted over a burning candle placed in a pan of water by formulating and testing six hypotheses. (Contains 43 references.) (Author/YDS)

  20. Gender Differences in Caribbean Students' Performance on a Test of Errors in Biological Labelling.

    ERIC Educational Resources Information Center

    Soyibo, Kola

    1999-01-01

    Discusses the performance of 11th-grade students from Barbados, Belize, Jamaica, St. Lucia, St. Vincent, and Trinidad (n=1216) on an Errors in Biological Labeling Test (EBLT). Concludes that performance was low in six categories of errors, and that girls performed significantly better on each category of error than did boys. Contains 15…

  1. 77 FR 22282 - Draft Guidelines on Biologics Quality Monitoring: Testing for the Detection of Mycoplasma...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-13

    ... Animal and Plant Health Inspection Service Draft Guidelines on Biologics Quality Monitoring: Testing for the Detection of Mycoplasma Contamination AGENCY: Animal and Plant Health Inspection Service, USDA... Service under the Virus-Serum-Toxin Act, we are requesting comments on the scope of the guideline and...

  2. Recent advances in sensitized mesoscopic solar cells.

    PubMed

    Grätzel, Michael

    2009-11-17

    -intensive high vacuum and materials purification steps that are currently employed in the fabrication of all other thin-film solar cells. Organic materials are abundantly available, so that the technology can be scaled up to the terawatt scale without running into feedstock supply problems. This gives organic-based solar cells an advantage over the two major competing thin-film photovoltaic devices, i.e., CdTe and CuIn(As)Se, which use highly toxic materials of low natural abundance. However, a drawback of the current embodiment of OPV cells is that their efficiency is significantly lower than that for single and multicrystalline silicon as well as CdTe and CuIn(As)Se cells. Also, polymer-based OPV cells are very sensitive to water and oxygen and, hence, need to be carefully sealed to avoid rapid degradation. The research discussed within the framework of this Account aims at identifying and providing solutions to the efficiency problems that the OPV field is still facing. The discussion focuses on mesoscopic solar cells, in particular, dye-sensitized solar cells (DSCs), which have been developed in our laboratory and remain the focus of our investigations. The efficiency problem is being tackled using molecular science and nanotechnology. The sensitizer constitutes the heart of the DSC, using sunlight to pump electrons from a lower to a higher energy level, generating in this fashion an electric potential difference, which can exploited to produce electric work. Currently, there is a quest for sensitizers that achieve effective harnessing of the red and near-IR part of sunlight, converting these photons to electricity better than the currently used generation of dyes. Progress in this area has been significant over the past few years, resulting in a boost in the conversion efficiency of the DSC that will be reviewed. PMID:19715294

  3. Human toxoplasmosis: which biological diagnostic tests are best suited to which clinical situations?

    PubMed

    Murat, Jean-Benjamin; Hidalgo, Hélène Fricker; Brenier-Pinchart, Marie-Pierre; Pelloux, Hervé

    2013-09-01

    The Toxoplasma gondii parasite is a worldwide threat most particularly in fetal life and immunosuppression. In most clinical situations (except in some ocular cases), correct detection or identification of toxoplasmosis requires biological analysis. This article considers the laboratory tools that have been developed in this field since the discovery of the pathogen, with emphasis on the most recent tests and how they can or should be used in different clinical situations. The authors also discuss the requirements and pitfalls that one should be aware of when biologically investigating this intriguing parasitosis. PMID:24053275

  4. Offer of rapid testing and alternative biological samples as practical tools to implement HIV screening programs.

    PubMed

    Parisi, Maria Rita; Soldini, Laura; Di Perri, Giovanni; Tiberi, Simon; Lazzarin, Adriano; Lillo, Flavia B

    2009-10-01

    Implementation of HIV testing has the objective to increase screening, identify and counsel persons with infection, link them to clinical services and reduce transmission. Rapid tests and/or alternative biological samples (like oral fluid) give the option for a better general consent in approaching screening, immediate referral of HIV positives to medical treatment and partner notification. We tested the performance characteristics of an oral fluid-based rapid HIV test (Rapidtest HIV lateral flow-Healthchem diag. LLC) in comparison with routinely utilized methods in a selected population of known positive (N = 121) or negative (N = 754) subjects. The sensitivity of the rapid test was 99.1% (one false negative sample) and the specificity 98.8%. Five negatives showed a faint reactivity, 3 of these were reactive also in the reference test, one with a p24 only reaction in Western blot. If these 3 samples were excluded from the analysis the specificity increases to 99.2%. Results from our study confirm that, although a continuous improvement of the test performance is still needed to minimize false negative and positive results, rapid test and alternative biological samples may contribute to HIV prevention strategies by reaching a larger population particularly when and where regular screening procedures are difficult to obtain. PMID:20128446

  5. Biology, host specificity tests, and risk assessment of the sawfly Heteroperreyia hubrichi, a potential biological control agent of Schinus terebinthifolius in Hawaii

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Abstract. Heteroperreyia hubrichi Malaise (Hymenoptera: Pergidae), a foliage feeding sawfly of Schinus terebinthifolius Raddi (Sapindales: Anacardiaceae), was studied to assess its suitability as a classical biological control agent of this invasive weed in Hawaii. Nochoice host-specificity tests we...

  6. Science Teacher Efficacy and Outcome Expectancy as Predictors of Students' End-of-Instruction (EOI) Biology I Test Scores

    ERIC Educational Resources Information Center

    Angle, Julie; Moseley, Christine

    2009-01-01

    The purpose of this study was to compare teacher efficacy beliefs of secondary Biology I teachers whose students' mean scores on the statewide End-of-Instruction (EOI) Biology I test met or exceeded the state academic proficiency level (Proficient Group) to teacher efficacy beliefs of secondary Biology I teachers whose students' mean scores on the…

  7. BEO-Life, a Test and Refurbishment Support for Biological Research Facilities

    NASA Astrophysics Data System (ADS)

    Engeln, I.; Hueser, D.; Reese, C.; Schoenfeld, R.

    Since the ISS commenced its operational phase, the need of ground based test and refurbishment support, facilitating the utilisation of the station and especially its facilities for biological research, becomes increasingly important.. The onboard biological research facilities (e.g. BIOLAB) are designed and built for a life time of 10 years, requiring the regular exchange of the integrated life support systems. The exact conditioning of the atmosphere in these systems plays an important role for the scientific outcome. The composition of the air (O2, N2 and CO2) as well as the humidity and the temperature inside the experiment chambers containing the plants and cell-cultures needs to be adjustable for various types of experiments. Since the various ingredients for a life support system are consumables, which consumption depends on the number of performed experiments, the life support systems needs to be refurbished from time to time. Our contribution to this challenge is BEO- Life, which offers a unique test, refurbishment and qualification environment for maintenance and re-supply for life support systems of the ISS onboard biological facilities. BEO-Life provides the ground support for all these tasks, such as tests, maintenance, verification and procedures. To fulfil the demanding requirements for the automatic and stable conditioning of the life support system, a complex arrangement of pumps, valves, sensors and an electronic system including software with exact control algorithms is provided. Beside the refurbishment activities, BEO-Life will support preliminary ground-based investigations of scientists before utilisation of the ISS biological research facilities, too. In conclusion, we offer a novel service element for the ground-based maintenance of biological research facilities onboard the ISS. This service can be easily adapted to the needs of users for preparatory work.

  8. An analytical study of seismoelectric signals produced by 1-D mesoscopic heterogeneities

    NASA Astrophysics Data System (ADS)

    Monachesi, Leonardo B.; Rubino, J. Germán; Rosas-Carbajal, Marina; Jougnot, Damien; Linde, Niklas; Quintal, Beatriz; Holliger, Klaus

    2015-04-01

    The presence of mesoscopic heterogeneities in fluid-saturated porous rocks can produce measurable seismoelectric signals due to wave-induced fluid flow between regions of differing compressibility. The dependence of these signals on the petrophysical and structural characteristics of the probed rock mass remains largely unexplored. In this work, we derive an analytical solution to describe the seismoelectric response of a rock sample, containing a horizontal layer at its centre, that is subjected to an oscillatory compressibility test. We then adapt this general solution to compute the seismoelectric signature of a particular case related to a sample that is permeated by a horizontal fracture located at its centre. Analyses of the general and particular solutions are performed to study the impact of different petrophysical and structural parameters on the seismoelectric response. We find that the amplitude of the seismoelectric signal is directly proportional to the applied stress, to the Skempton coefficient contrast between the host rock and the layer, and to a weighted average of the effective excess charge of the two materials. Our results also demonstrate that the frequency at which the maximum electrical potential amplitude prevails does not depend on the applied stress or the Skempton coefficient contrast. In presence of strong permeability variations, this frequency is rather controlled by the permeability and thickness of the less permeable material. The results of this study thus indicate that seismoelectric measurements can potentially be used to estimate key mechanical and hydraulic rock properties of mesoscopic heterogeneities, such as compressibility, permeability and fracture compliance.

  9. Biological and chemical tests of contaminated soils to determine bioavailability and environmentally acceptable endpoints (EAE)

    SciTech Connect

    Montgomery, C.R.; Menzie, C.A.; Pauwells, S.J.

    1995-12-31

    The understanding of the concept of bioavailability of soil contaminants to receptors and its use in supporting the development of EAE is growing but still incomplete. Nonetheless, there is increased awareness of the importance of such data to determine acceptable cleanup levels and achieve timely site closures. This presentation discusses a framework for biological and chemical testing of contaminated soils developed as part of a Gas Research Institute (GRI) project entitled ``Environmentally Acceptable Endpoints in Soil Using a Risk Based Approach to Contaminated Site Management Based on Bioavailability of Chemicals in Soil.`` The presentation reviews the GRI program, and summarizes the findings of the biological and chemical testing section published in the GRI report. The three primary components of the presentation are: (1) defining the concept of bioavailability within the existing risk assessment paradigm, (2) assessing the usefulness of the existing tests to measure bioavailability and test frameworks used to interpret these measurements, and (3) suggesting how a small selection of relevant tests could be incorporated into a flexible testing scheme for soils to address this issue.

  10. Flux flow in current driven mesoscopic superconductors: size effects

    NASA Astrophysics Data System (ADS)

    Sánchez-Lotero, Pedro; Domínguez, Daniel; Albino Aguiar, J.

    2016-06-01

    Flux-flow phenomena in a superconducting mesoscopic stripe submitted to an applied current and external magnetic field is studied. The time-dependent Ginzburg-Landau equations are solved numerically to obtain the electric and magnetic response of the system. It is shown that the I- V curves, for the wider strips, present a universal behaviour. The dependence of the flux-flow resistivity on the magnetic field and width allow us to propose a criterion characterizing, both, the macroscopic and mesoscopic regimes. The power spectrum of the average voltage permits identifying the effect of surface currents in vortices movement. Based on the maximum value of the power spectrum first harmonic we propose a geometric condition for matching between the sample dimensions and the vortex lattice parameter.

  11. Robust mesoscopic superposition of strongly correlated ultracold atoms

    SciTech Connect

    Hallwood, David W.; Ernst, Thomas; Brand, Joachim

    2010-12-15

    We propose a scheme to create coherent superpositions of annular flow of strongly interacting bosonic atoms in a one-dimensional ring trap. The nonrotating ground state is coupled to a vortex state with mesoscopic angular momentum by means of a narrow potential barrier and an applied phase that originates from either rotation or a synthetic magnetic field. We show that superposition states in the Tonks-Girardeau regime are robust against single-particle loss due to the effects of strong correlations. The coupling between the mesoscopically distinct states scales much more favorably with particle number than in schemes relying on weak interactions, thus making particle numbers of hundreds or thousands feasible. Coherent oscillations induced by time variation of parameters may serve as a 'smoking gun' signature for detecting superposition states.

  12. Mesoscopic stability and sedimentation waves in settling periodic arrays.

    PubMed

    Felderhof, B U

    2003-11-01

    The stability of a periodic array of particles settling in a viscous incompressible fluid under the influence of gravity is investigated in the framework of the point sedimentation model. The simple cubic array is unstable, but the body-centered and face-centered cubic arrays with gravity directed along one of the crystal axes are mesoscopically stable, i.e., they are stable except for very long wavelength in a certain domain of directions of the wave vector. In such mesoscopically stable arrays the instability is suppressed in periodic boundary conditions for systems smaller than a maximum size. In a stable finite system the particles perform small motions about the positions of the regular array, and sedimentation waves propagate through the system. PMID:14682796

  13. [Testing the sterilisation effect of autoclaves by means of biological indicators (author's transl)].

    PubMed

    Werner, H P; Kindt, R; Borneff, J

    1975-07-01

    Because of the great number of failures with sterilization-programs it seems to be necessary to check up the effect of sterilization not only by the annual official tests but also continuously with biological indicators. Marketable indicators have not to be tested necessarily at present. Therefore six different types of indicators were examined experimentally and under practice-conditions. As to be seen in table 1 samples of the same charge didn't show great differences, in spite of this germ-counts of several charges differed considerably. Reductions of germ-counts after sterilization in the autoclave at 123,5 degrees C (fig. 1) and at 134 degrees C (fig 2), as well as with hot air at 120-125 degrees C (fig 3) and 133-138 degrees C (fig 4) demonstrate the heat-resistance. The individual biological indicators differ in killing-time and times of survival (table 2). Our tests demonstrate that only single biological indicators (table 4) will grant satisfying results in continuous checking of sterilization process. PMID:811008

  14. Counting statistics for mesoscopic conductors with internal degrees of freedom.

    PubMed

    Birchall, Christopher; Schomerus, Henning

    2010-07-01

    We consider the transport of electrons passing through a mesoscopic device possessing internal dynamical quantum degrees of freedom. The mutual interaction between the system and the conduction electrons contributes to the current fluctuations, which we describe in terms of full counting statistics. We identify conditions where this discriminates coherent from incoherent internal dynamics and also identify and illustrate conditions under which the device acts to dynamically bunch transmitted or reflected electrons, thereby generating super-Poissonian noise. PMID:20867723

  15. Vortex states and magnetization curve of square mesoscopic superconductors.

    SciTech Connect

    Melnikov, A. S.; Nefedov, I. M.; Ryzhov, D. A.; Shereshevskii, I. A.; Vinokur, V. M.; Vysheslavtsev, P. P.; Materials Science Division; Russian Academy of Sciences

    2002-03-22

    The structure of the vortex states in a square mesoscopic superconductor is analyzed in detail using the numerical simulation within the time-dependent Ginzburg-Landau (TDGL) theory. Various vortex states (vortices, vortex molecules, multiquanta vortices) are observed and the magnetization curve is obtained. Different changes in vortex structures are identified with the peculiarities on the magnetization curve. Stability of a state consisting of vortices and antivortices is discussed.

  16. Phosphorus recycling potential assessment by a biological test applied to wastewater sludge.

    PubMed

    Braak, Etienne; Auby, Sarah; Piveteau, Simon; Guilayn, Felipe; Daumer, Marie-Line

    2016-01-01

    Phosphorus (P) recycling as mineral fertilizer from wastewater activated sludge (WAS) depends on the amount that can be dissolved and separated from the organic matter before the final crystallization step. The aim of the biological phosphorus dissolution potential (BPDP) test developed here was to assess the maximum amount of P that could be biologically released from WAS prior that the liquid phase enters the recovery process. It was first developed for sludge combining enhanced biological phosphorus removal and iron chloride. Because carbohydrates are known to induce acidification during the first stage of anaerobic digestion, sucrose was used as a co-substrate. Best results were obtained after 24-48 h, without inoculum, with a sugar/sludge ratio of 0.5 gCOD/gVS and under strict anaerobic conditions. Up to 75% of the total phosphorus in sludge from a wastewater treatment plant combining enhanced biological phosphorus removal and iron chloride phosphorus removal could be dissolved. Finally, the test was applied to assess BPDP from different sludge using alum compounds for P removal. No dissolution was observed when alum polychloride was used and less than 20% when alum sulphate was used. In all the cases, comparison to chemical acidification showed that the biological process was a major contributor to P dissolution. The possibility to crystallize struvite was discussed from the composition of the liquids obtained. The BPDP will be used not only to assess the potential for phosphorus recycling from sludge, but also to study the influence of the co-substrates available for anaerobic digestion of sludge. PMID:26786893

  17. An investigation of algebraic quantum dynamics for mesoscopic coupled electric circuits with mutual inductance

    NASA Astrophysics Data System (ADS)

    Pahlavani, H.; Kolur, E. Rahmanpour

    2016-08-01

    Based on the electrical charge discreteness, the Hamiltonian operator for the mutual inductance coupled quantum mesoscopic LC circuits has been found. The persistent current on two driven coupled mesoscopic electric pure L circuits (two quantum loops) has been obtained by using algebraic quantum dynamic approach. The influence of the mutual inductance on energy spectrum and quantum fluctuations of the charge and current for two coupled quantum electric mesoscopic LC circuits have been investigated.

  18. Energy relaxation rate and its mesoscopic fluctuations in quantum dots

    NASA Astrophysics Data System (ADS)

    Kozii, Vladyslav A.; Skvortsov, Mikhail A.

    2016-08-01

    We analyze the applicability of the Fermi-golden-rule description of quasiparticle relaxation in a closed diffusive quantum dot with electron-electron interaction. Assuming that single-particle levels are already resolved but the initial stage of quasiparticle disintegration can still be described by a simple exponential decay, we calculate the average inelastic energy relaxation rate of single-particle excitations and its mesoscopic fluctuations. The smallness of mesoscopic fluctuations can then be used as a criterion for the validity of the Fermi-golden-rule description. Technically, we implement the real-space Keldysh diagram technique, handling correlations in the quasi-discrete spectrum non-perturbatively by means of the non-linear supersymmetric sigma model. The unitary symmetry class is considered for simplicity. Our approach is complementary to the lattice-model analysis of Fock space: though we are not able to describe many-body localization, we derive the exact lowest-order expression for mesoscopic fluctuations of the relaxation rate, making no assumptions on the matrix elements of the interaction. It is shown that for the quasiparticle with the energy ε on top of the thermal state with the temperature T, fluctuations of its energy width become large and the Fermi-golden-rule description breaks down at max { ε , T } ∼ Δ√{ g }, where Δ is the mean level spacing in the quantum dot, and g is its dimensionless conductance.

  19. Combining molecular dynamics with mesoscopic Green's function reaction dynamics simulations

    NASA Astrophysics Data System (ADS)

    Vijaykumar, Adithya; Bolhuis, Peter G.; ten Wolde, Pieter Rein

    2015-12-01

    In many reaction-diffusion processes, ranging from biochemical networks, catalysis, to complex self-assembly, the spatial distribution of the reactants and the stochastic character of their interactions are crucial for the macroscopic behavior. The recently developed mesoscopic Green's Function Reaction Dynamics (GFRD) method enables efficient simulation at the particle level provided the microscopic dynamics can be integrated out. Yet, many processes exhibit non-trivial microscopic dynamics that can qualitatively change the macroscopic behavior, calling for an atomistic, microscopic description. We propose a novel approach that combines GFRD for simulating the system at the mesoscopic scale where particles are far apart, with a microscopic technique such as Langevin dynamics or Molecular Dynamics (MD), for simulating the system at the microscopic scale where reactants are in close proximity. This scheme defines the regions where the particles are close together and simulated with high microscopic resolution and those where they are far apart and simulated with lower mesoscopic resolution, adaptively on the fly. The new multi-scale scheme, called MD-GFRD, is generic and can be used to efficiently simulate reaction-diffusion systems at the particle level.

  20. A mesoscopic Rydberg impurity in an atomic quantum gas

    NASA Astrophysics Data System (ADS)

    Schmidt, Richard; Sadeghpour, Hossein; Demler, Eugene

    2016-05-01

    Impurity problems have been at the forefront of research in condensed matter physics for several decades. In this talk, we show that Rydberg impurity excitations in ultracold quantum gases present a new frontier in impurity research. Here vastly different energy scales compete, signified in deeply bound Rydberg molecules of mesoscopic size. This situation poses a new challenge for theoretical physics and necessitates the confluence of methods ranging from mesoscopic to atomic physics. In our work, we develop a novel many-body theory for the non-equilibrium dynamics of giant impurity excitations Bose gases. Such single Rydberg impurity excitations have recently been observed, and we demonstrate that the observations can be understood from our theoretical approach which incorporates atomic and many-body theory. The crossover from few-body dynamics to quantum many-body collective behavior - manifest in the appearance of a novel superpolaronic state - is elucidated in our unified functional determinant approach, valid at zero and finite temperature. The time-dependent formalism is not restricted to Rydberg systems but can be generally applied to impurities in bosonic and fermionic environments and opens new possibilities to study impurity dynamics in mesoscopic systems.

  1. Insects as test systems for assessing the potential role of microgravity in biological development and evolution

    NASA Astrophysics Data System (ADS)

    Vernós, I.; Carratalá, M.; González-Jurado, J.; Valverde, J. R.; Calleja, M.; Domingo, A.; Vinós, J.; Cervera, M.; Marco, R.

    Gravity and radiation are undoubtedly the two major environmental factors altered in space. Gravity is a weak force, which creates a permanent potential field acting on the mass of biological systems and their cellular components, strongly reduced in space flights. Developmental systems, particularly at very early stages, provide the larger cellular compartments known, where the effects of alterations in the size of the gravity vector on living organisms can be more effectively tested. The insects, one of the more highly evolved classes of animals in which early development occurs in a syncytial embryo, are systems particularly well suited to test these effects and the specific developmental mechanisms affected. Furthermore, they share some basic features such as small size, short life cycles, relatively high radio-resistance, etc. and show a diversity of developmental strategies and tempos advantageous in experiments of this type in space. Drosophila melanogaster, the current biological paradigm to study development, with so much genetic and evolutionary background available, is clearly the reference organism for these studies. The current evidence on the effects of the physical parameters altered in space flights on insect development indicate a surprising correlation between effects seen on the fast developing and relatively small Drosophila embryo and the more slowly developing and large Carausius morosus system. In relation to the issue of the importance of developmental and environmental constraints in biological evolution, still the missing link in current evolutionary thinking, insects and space facilities for long-term experiments could provide useful experimental settings where to critically assess how development and evolution may be interconnected. Finally, it has to be pointed out that since there are experimental data indicating a possible synergism between microgravity and space radiation, possible effects of space radiation should be taken into

  2. Detecting Change in Biological Rhythms: A Multivariate Permutation Test Approach to Fourier-Transformed Data

    PubMed Central

    Blackford, Jennifer Urbano; Salomon, Ronald M.; Waller, Niels G.

    2009-01-01

    Treatment-related changes in neurobiological rhythms are of increasing interest to psychologists, psychiatrists, and biological rhythms researchers. New methods for analyzing change in rhythms are needed, as most common methods disregard the rich complexity of biological processes. Large time series data sets reflect the intricacies of underlying neurobiological processes, but can be difficult to analyze. We propose the use of Fourier methods with multivariate permutation test (MPT) methods for analyzing change in rhythms from time series data. To validate the use of MPT for Fourier-transformed data, we performed Monte Carlo simulations and compared statistical power and family-wise error for MPT to Bonferroni-corrected and uncorrected methods. Results show that MPT provides greater statistical power than Bonferroni-corrected tests, while appropriately controlling family-wise error. We applied this method to human, pre-and post-treatment, serially-sampled neurotransmitter data to confirm the utility of this method using real data. Together, Fourier with MPT methods provides a statistically powerful approach for detecting change in biological rhythms from time series data. PMID:19212840

  3. METHODS FOR USING 3-D ULTRASOUND SPECKLE TRACKING IN BIAXIAL MECHANICAL TESTING OF BIOLOGICAL TISSUE SAMPLES

    PubMed Central

    Yap, Choon Hwai; Park, Dae Woo; Dutta, Debaditya; Simon, Marc; Kim, Kang

    2014-01-01

    Being multilayered and anisotropic, biological tissues such as cardiac and arterial walls are structurally complex, making full assessment and understanding of their mechanical behavior challenging. Current standard mechanical testing uses surface markers to track tissue deformations and does not provide deformation data below the surface. In the study described here, we found that combining mechanical testing with 3-D ultrasound speckle tracking could overcome this limitation. Rat myocardium was tested with a biaxial tester and was concurrently scanned with high-frequency ultrasound in three dimensions. The strain energy function was computed from stresses and strains using an iterative non-linear curve-fitting algorithm. Because the strain energy function consists of terms for the base matrix and for embedded fibers, spatially varying fiber orientation was also computed by curve fitting. Using finite-element simulations, we first validated the accuracy of the non-linear curve-fitting algorithm. Next, we compared experimentally measured rat myocardium strain energy function values with those in the literature and found a matching order of magnitude. Finally, we retained samples after the experiments for fiber orientation quantification using histology and found that the results satisfactorily matched those computed in the experiments. We conclude that 3-D ultrasound speckle tracking can be a useful addition to traditional mechanical testing of biological tissues and may provide the benefit of enabling fiber orientation computation. PMID:25616585

  4. - and Mesoscopic Soft Condensed Matter Architectures on Semiconductor Surfaces

    NASA Astrophysics Data System (ADS)

    Samuilov, Vladimir; Seo, Young-Soo; Ksenevich, Vitaly; Galibert, Jean; Sokolov, John; Rafailovich, Miriam

    2003-03-01

    A novel and simple approach of self-organized fabrication of two dimensional mesoscopic networks with the feature size down to 50 nm has been developed. The technique is based on the self-organized patterning in a thin layer of complex liquid (polymer solution) in the presence of humid atmosphere. Two dimensional mesoscopic honeycomb-shaped carbon structures were produced by high temperature annealing of nitrocellulose precursors [1]. The polymer network was also utilized as a mask for further reactive ion etching of surfaces with epi-layer of GaAs [2,3] and GaAs/AlGaAs ? -doped heterostructures [4]. The electrical transport in the obtained structures was studied in a temperature range from 1.9 to 300 K and in pulsed magnetic fields up to 35 T. A crossover from the Mott variable range hopping to the Colomb-gap Efros-Shklovskii variable range hopping has been observed experimentally in mesoscopic carbon structures [1]. At low fields, ln(R/R0) is proportional to B2. In the intermediate range, the magnetoresistance is linear on B. At high temperatures, if the hopping distance is comparable to the localization length, the observed small negative magnetoresistance in our samples is consistent to the weak-localization picture. Magnetoresistance of patterned GaAs/AlGaAs ?-doped structures is negative [4], which is relater to quantum interference in hopping regime. At B=0, the resistance showed typical behavior of a two-dimensional hopping. Below about 20 K, the data followed the Mott variable-range-hopping mechanism for two dimensions. Also, we have used diblock-copolymer system, self-assembled with L-B technique, to produce nano-patterns. These structures were utilized as templates for introducing metal nanopatterns on semiconductor surfaces by reactive ion beam etching for magnetic storage systems [5] and DNA separation on a flat surface [6] devices. 1. V.A. Samuilov, J. Galibert, V.K. Ksenevich, V.J. Goldman, M. Rafailovich, J. Sokolov, I.A. Bashmakov, V.A. Dorosinets

  5. HRI catalytic two-stage liquefaction (CTSL) process materials: chemical analysis and biological testing

    SciTech Connect

    Wright, C.W.; Later, D.W.

    1985-12-01

    This report presents data from the chemical analysis and biological testing of coal liquefaction materials obtained from the Hydrocarbon Research, Incorporated (HRI) catalytic two-stage liquefaction (CTSL) process. Materials from both an experimental run and a 25-day demonstration run were analyzed. Chemical methods of analysis included adsorption column chromatography, high-resolution gas chromatography, gas chromatography/mass spectrometry, low-voltage probe-inlet mass spectrometry, and proton nuclear magnetic resonance spectroscopy. The biological activity was evaluated using the standard microbial mutagenicity assay and an initiation/promotion assay for mouse-skin tumorigenicity. Where applicable, the results obtained from the analyses of the CTSL materials have been compared to those obtained from the integrated and nonintegrated two-stage coal liquefaction processes. 18 refs., 26 figs., 22 tabs.

  6. [Plasma antioxidant activity--a test for impaired biological functions of endoecology, exotrophy, and inflammation reactions].

    PubMed

    Titov, V N; Krylin, V V; Dmitriev, V A; Iashin, Ia I

    2010-07-01

    The authors discuss the diagnostic value of a test for total serum antioxidant activity determined by an electrochemistry method on a liquid chromatograph (without a column), by using an amperometric detector, as well as the composition of the endogenously synthesized hydrophilic and hydrophobic acceptors of reactive oxygen species (ROS). Uric acid is a major hydrophilic acceptor of ROS; monoenic oleic fatty acid acts as its major lipophilic acceptor. The constant determined by the authors for of 03 oleic acid oxidation during automatic titration in the organic medium is an order of magnitude higher than that for alpha-tocopherol, beta-carotene and linoleic fatty acid; its concentration is also an order of magnitude higher. In oxidative stress, the adrenal steroid hormone dehydroepiandrosterone initiates oleic acid synthesis via expression of palmitoyl elongase and steatoryl desaturase. In early steps of phylogenesis in primates, spontaneous mutation resulted in ascorbic acid synthesis gene knockout; phylogenetically, further other mutation knocked out the gene encoding the synthesis of uricase and the conversion of uric acid to alantoin. In primates, uric acid became not only a catabolite of purine bases in vivo, but also the major endogenous hydrophilic acceptor of ROS. This philogenetic order makes it clear why the epithelium in the proximal nephron tubule entirely reabsorbs uric acid (a catabolite?) from primary urine and then secretes it again to urine depending on the impairment of biological functions of endoecology (the intercellular medium being contaminated with biological rubbish), the activation of a biological inflammatory reaction, the cellular production of ROS, and the reduction in serum total antioxidant activity. With each biological reaction, there was an increase in the blood content of uric acid as a hydrophilic acceptor of ROS, by actively lowering its secretion into urine. Uric acid is a diagnostic test of inflammation, or rather compensatory

  7. Ergometer error and biological variation in power output in a performance test with three cycle ergometers.

    PubMed

    Paton, C D; Hopkins, W G

    2006-06-01

    When physical performance is monitored with an ergometer, random error arising from the ergometer combines with biological variation from the subject to limit the precision of estimation of performance changes. We report here the contributions of ergometer error and biological variation to the error of measurement in a performance test with two popular cycle ergometers (air-braked Kingcycle, mobile SRM crankset) and a relatively new inexpensive mobile ergometer (PowerTap hub). Eleven well-trained male cyclists performed a familiarization trial followed by three 5-min time trials within 2 wk on a racing cycle fitted with the SRM and PowerTap and mounted on the Kingcycle. Mean power output in each trial was recorded with all ergometers simultaneously. A novel analysis using mixed modelling of log-transformed mean power provided estimates of the standard error of measurement as a coefficient of variation and its components arising from the ergometer and the cyclists. The usual errors of measurement were: Kingcycle 2.2 %, PowerTap 1.5 %, and SRM 1.6 % (90 % confidence limits +/- 1.3). The components of these errors arising purely from the ergometers and the cyclists were: Kingcycle 1.8 %, PowerTap 0.9 %, SRM 1.1 %, and cyclists 1.2 % (+/- 1.5). Thus, ergometer errors and biological variation made substantial contributions to the usual error of measurement. Use of the best ergometers and of test protocols that reduce biological variation would improve monitoring of the small changes that matter to elite athletes. PMID:16767608

  8. Assessment of a multi-assay biological diagnostic test for mood disorders in a Japanese population.

    PubMed

    Yamamori, Hidenaga; Ishima, Tamaki; Yasuda, Yuka; Fujimoto, Michiko; Kudo, Noriko; Ohi, Kazutaka; Hashimoto, Kenji; Takeda, Masatoshi; Hashimoto, Ryota

    2016-01-26

    The current diagnostic tests for mood disorders, including major depressive disorder (MDD) and bipolar disorder (BD), have limitations. Inflammatory markers, growth factors, and oxidative stress markers are involved in the pathophysiology of mood disorders. A multi-assay biological diagnostic test combining these biomarkers might improve diagnostic efficiency. The plasma levels of soluble tumor necrosis factor receptor 2 (sTNFR2), epidermal growth factor (EGF), and myeloperoxidase were measured in 40 MDD patients, 40 BD patients and 40 controls in a Japanese population. We also investigated the plasma levels of these markers in 40 patients with schizophrenia to determine the utility of these markers in differential diagnosis. The plasma levels of sTNFR2 were significantly higher in BD and schizophrenia patients than in controls. The plasma levels of EGF and myeloperoxidase were significantly higher in patients with BD than in controls. The correct classification rate obtained from discriminant analysis with sTNFR2 and EGF between controls and mood disorders was 69.2%, with a sensitivity and specificity of 62.5% and 82.5%, respectively. The correct classification rate obtained from discriminant analysis with sTNFR2 and EGF between controls and BD was 85.0%, with a sensitivity and specificity of 77.6% and 92.5%, respectively. Our results suggest that sTNFR2 and EGF could be biological markers of BD. Further studies are needed to determine the utility of these markers in diagnostic tests for mood disorders. PMID:26687272

  9. Inquiry-based laboratory investigations and student performance on standardized tests in biological science

    NASA Astrophysics Data System (ADS)

    Patke, Usha

    Achievement data from the 3rd International Mathematics and Sciences Study and Program for International Student Assessment in science have indicated that Black students from economically disadvantaged families underachieve at alarming rates in comparison to White and economically advantaged peer groups. The study site was a predominately Black, urban school district experiencing underachievement. The purpose of this correlational study was to examine the relationship between students' use of inquiry-based laboratory investigations and their performance on the Biology End of Course Test, as well as to examine the relationship while partialling out the effects of student gender. Constructivist theory formed the theoretical foundation of the study. Students' perceived levels of experience with inquiry-based laboratory investigations were measured using the Laboratory Program Variable Inventory (LPVI) survey. LPVI scores of 256 students were correlated with test scores and were examined by student gender. The Pearson correlation coefficient revealed a small direct correlation between students' experience in inquiry-based laboratory investigation classes and standardized test scores on the Biology EOCT. A partial correlational analysis indicated that the correlation remained after controlling for gender. This study may prompt a change from teacher-centered to student-centered pedagogy at the local site in order to increase academic achievement for all students. The results of this study may also influence administrators and policy makers to initiate local, state, or nationwide curricular development. A change in curriculum may promote social change as students become more competent, and more able, to succeed in life beyond secondary school.

  10. [Biological testing of fibrogenic effect of dust from the "Gliwice" mine on the lung tissue].

    PubMed

    Zyłka-Włoszczyk, M; Szymczykiewicz, K; Szaflarska-Stojko, E; Olczyk, D

    1990-01-01

    Animal study was carried out to determine biological aggressiveness of mining dust by means of pulmonary tests. Dust samples, 50 mg settled dust, a mixture from 3 different mine layers (sample A) and 50 mg dust collected by the gravimetric method from different mine layers (sample B) were administered in two respective test groups by a single intratracheal injection. Silica content, determined according to Polezhayev, was found to range from 4.6% (sample A) to 12.7% (sample B). In months 3 and 6 of the experiment lung content of hydroxyproline was determined following Stegemann. Biochemical tests for hydroxyproline content revealed highest increase in the lungs of Group 2 animals 6 months after the onset of the experiment (10.312 mg). Very similar result was obtained in Group 1, with injected settled dust mixture: hydroxyproline level amounted to 10.214 mg. Both sample A and sample B induced elevated level of lung hydroxyproline although silica content in dust sample differed considerably. The study revealed that the biological aggressiveness of settled dust was not proportionate to the content of pure silica. It is thought that increased fibrogenic potentials of the settled dust may have resulted from defected crystalline structure of silica due to the grinding of the mineral in a hand-mill. PMID:2215202

  11. Collaborative Testing Improves Performance but Not Content Retention in a Large-Enrollment Introductory Biology Class

    PubMed Central

    Leight, Hayley; Saunders, Cheston; Calkins, Robin; Withers, Michelle

    2012-01-01

    Collaborative testing has been shown to improve performance but not always content retention. In this study, we investigated whether collaborative testing could improve both performance and content retention in a large, introductory biology course. Students were semirandomly divided into two groups based on their performances on exam 1. Each group contained equal numbers of students scoring in each grade category (“A”–“F”) on exam 1. All students completed each of the four exams of the semester as individuals. For exam 2, one group took the exam a second time in small groups immediately following the individually administered test. The other group followed this same format for exam 3. Individual and group exam scores were compared to determine differences in performance. All but exam 1 contained a subset of cumulative questions from the previous exam. Performances on the cumulative questions for exams 3 and 4 were compared for the two groups to determine whether there were significant differences in content retention. Even though group test scores were significantly higher than individual test scores, students who participated in collaborative testing performed no differently on cumulative questions than students who took the previous exam as individuals. PMID:23222835

  12. Chemical analysis and biological testing of materials from the EDS coal liquefaction process: a status report

    SciTech Connect

    Later, D.W.; Pelroy, R.A.; Wilson, B.W.

    1984-05-01

    Representative process materials were obtained from the EDS pilot plant for chemical and biological analyses. These materials were characterized for biological activity and chemical composition using a microbial mutagenicity assay and chromatographic and mass spectrometric analytical techniques. The two highest boiling distillation cuts, as well as process solvent (PS) obtained from the bottoms recycle mode operation, were tested for initiation of mouse skin tumorigenicity. All three materials were active; the crude 800/sup 0 +/F cut was substantially more potent than the crude bottoms recycle PS or 750 to 800/sup 0/F distillate cut. Results from chemical analyses showed the EDS materials, in general, to be more highly alkylated and have higher hydroaromatic content than analogous SRC II process materials (no in-line process hydrogenation) used for comparison. In the microbial mutagenicity assays the N-PAC fractions showed greater activity than did the aliphatic hydrocarbon, hydroxy-PAH, or PAH fractions, although mutagenicity was detected in certain PAH fractions by a modified version of the standard microbial mutagenicity assay. Mutagenic activities for the EDS materials were lower, overall, than those for the corresponding materials from the SRC II process. The EDS materials produced under different operational modes had distinguishable differences in both their chemical constituency and biological activity. The primary differences between the EDS materials studied here and their SRC II counterparts used for comparison are most likely attributable to the incorporation of catalytic hydrogenation in the EDS process. 27 references, 28 figures, 27 tables.

  13. Pre-release efficacy test of the prospective biological control agent Arytinnis hakani on the invasive weed Genista monspessulana

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In weed biological control, conducting a pre-release efficacy test can help ascertain if prospective biological control agents will be capable of controlling the target plant. Currently, the phloem-feeding psyllid, Arytinnis hakani, is being evaluated as a prospective agent for the exotic invasive w...

  14. The Development and Testing of Environmental and Societal-Related College General Biology Laboratory Experiences. Final Report.

    ERIC Educational Resources Information Center

    Lucido, Phillip J.

    The purpose of this project was to develop and test the effectiveness of relevant and functional general biology laboratory experiences based on the various media with which the student came in day-to-day contact. The review of the literature pertaining to the development of innovative general biology laboratory procedures for the college level…

  15. DAISY: a new software tool to test global identifiability of biological and physiological systems.

    PubMed

    Bellu, Giuseppina; Saccomani, Maria Pia; Audoly, Stefania; D'Angiò, Leontina

    2007-10-01

    A priori global identifiability is a structural property of biological and physiological models. It is considered a prerequisite for well-posed estimation, since it concerns the possibility of recovering uniquely the unknown model parameters from measured input-output data, under ideal conditions (noise-free observations and error-free model structure). Of course, determining if the parameters can be uniquely recovered from observed data is essential before investing resources, time and effort in performing actual biomedical experiments. Many interesting biological models are nonlinear but identifiability analysis for nonlinear system turns out to be a difficult mathematical problem. Different methods have been proposed in the literature to test identifiability of nonlinear models but, to the best of our knowledge, so far no software tools have been proposed for automatically checking identifiability of nonlinear models. In this paper, we describe a software tool implementing a differential algebra algorithm to perform parameter identifiability analysis for (linear and) nonlinear dynamic models described by polynomial or rational equations. Our goal is to provide the biological investigator a completely automatized software, requiring minimum prior knowledge of mathematical modelling and no in-depth understanding of the mathematical tools. The DAISY (Differential Algebra for Identifiability of SYstems) software will potentially be useful in biological modelling studies, especially in physiology and clinical medicine, where research experiments are particularly expensive and/or difficult to perform. Practical examples of use of the software tool DAISY are presented. DAISY is available at the web site http://www.dei.unipd.it/~pia/. PMID:17707944

  16. Molecular and Biological Diagnostic Tests for Monitoring Benzimidazole Resistance in Human Soil-Transmitted Helminths

    PubMed Central

    Diawara, Aïssatou; Schwenkenbecher, Jan M.; Kaplan, Ray M.; Prichard, Roger K.

    2013-01-01

    In endemic countries with soil-transmitted helminths mass drug administration with albendazole or mebendazole are being implemented as a control strategy. However, it is well known in veterinary helminths that the use of the same benzimidazole drugs can place selection on the β-tubulin gene, leading to resistance. Given the concern that resistance could arise in human soil-transmitted helminths, there is an urgent need to develop accurate diagnostic tools for monitoring resistance. In this study, we developed molecular assays to detect putative resistance genetic changes in Ascaris lumbricoides, Trichuris trichiura, and hookworms, and we optimized an egg hatch assay for the canine hookworm Ancylostoma caninum and applied it to Necator americanus. Both assays were tested on field samples. The molecular assays demonstrated their reproducibility and capacity to detect the presence of worms carrying putative resistance-associated genetic changes. However, further investigations are needed to validate our molecular and biological tests on additional field isolates. PMID:23458960

  17. Testing and characterization of a biologically-inspired first-order directional MEMS microphone

    NASA Astrophysics Data System (ADS)

    Antonelli, Daniel

    First-order directional microphones have a response that is proportional to the spatial gradient of sound pressure. The overall response, however, will also be influenced by the average sound pressure acting on the microphone diaphragm. For directional microphones to exhibit the desired first-order figure-8 directivity pattern, the response must be dominated by the pressure gradient rather than the pressure. A testing process has been developed to characterize the acoustic response of a biologically-inspired first-order directional MEMS microphone by separating the total measured response into the response due to the spatial average of the pressure and the response due to pressure gradient. Understanding how the pressure and pressure gradient of a sound field separately influence the overall behavior of this class of microphone is critical to assessing their performance. An experimental test setup and data processing algorithms have been developed which are shown to successfully achieve these goals.

  18. Molecular and biological diagnostic tests for monitoring benzimidazole resistance in human soil-transmitted helminths.

    PubMed

    Diawara, Aïssatou; Schwenkenbecher, Jan M; Kaplan, Ray M; Prichard, Roger K

    2013-06-01

    In endemic countries with soil-transmitted helminths mass drug administration with albendazole or mebendazole are being implemented as a control strategy. However, it is well known in veterinary helminths that the use of the same benzimidazole drugs can place selection on the β-tubulin gene, leading to resistance. Given the concern that resistance could arise in human soil-transmitted helminths, there is an urgent need to develop accurate diagnostic tools for monitoring resistance. In this study, we developed molecular assays to detect putative resistance genetic changes in Ascaris lumbricoides, Trichuris trichiura, and hookworms, and we optimized an egg hatch assay for the canine hookworm Ancylostoma caninum and applied it to Necator americanus. Both assays were tested on field samples. The molecular assays demonstrated their reproducibility and capacity to detect the presence of worms carrying putative resistance-associated genetic changes. However, further investigations are needed to validate our molecular and biological tests on additional field isolates. PMID:23458960

  19. Electrophoresis tests on STS-3 and ground control experiments - A basis for future biological sample selections

    NASA Technical Reports Server (NTRS)

    Morrison, D. R.; Lewis, M. L.

    1982-01-01

    Static zone electrophoresis is an electrokinetic method of separating macromolecules and small particles. However, its application for the isolation of biological cells and concentrated protein solutions is limited by sedimentation and convection. Microgravity eliminates or reduces sedimentation, floatation, and density-driven convection arising from either Joule heating or concentration differences. The advantages of such an environment were first demonstrated in space during the Apollo 14 and 16 missions. In 1975 the Electrophoresis Technology Experiment (MA-011) was conducted during the Apollo-Soyuz Test Project flight. In 1979 a project was initiated to repeat the separations of human kidney cells. One of the major objectives of the Electrophoresis Equipment Verification Tests (EEVT) on STS-3 was to repeat and thereby validate the first successful electrophoretic separation of human kidney cells. Attention is given to the EEVT apparatus, the preflight electrophoresis, and inflight operational results.

  20. Support for the revocation of general safety test regulations in biologics license applications.

    PubMed

    Evans, Dana M; Thorn, Jennifer M; Arch-Douglas, Katherine; Sperry, Justin B; Thompson, Bruce; Davis, Heather L; McCluskie, Michael J

    2016-05-01

    The United States Food and Drug Administration recently removed the requirement for a General Safety Test (GST) for biologics in the Code of Federal Regulations (21 CFR 610.11). The GST, as well as abnormal toxicity (European Pharmacopeia) and innocuity tests (World Health Organization), were designed to test for extraneous toxic contaminants on each product lot intended for human use. Tests require one-week observations for general health and weight following injection of specified volumes of product batches into guinea pigs and mice. At the volumes specified, dose-related toxicity may result when the product is pharmacologically active in rodents. With vaccines, required doses may be > 3 logs higher than intended human dose on a weight-adjusted basis and if an immune modulatory adjuvant is included, systemic immune hyperactivation may cause toxicity. Herein, using the CpG/alum adjuvant combination we evaluated the different test protocols and showed their unsuitability for this adjuvant combination. PMID:26996102

  1. In silico model-based inference: a contemporary approach for hypothesis testing in network biology

    PubMed Central

    Klinke, David J.

    2014-01-01

    Inductive inference plays a central role in the study of biological systems where one aims to increase their understanding of the system by reasoning backwards from uncertain observations to identify causal relationships among components of the system. These causal relationships are postulated from prior knowledge as a hypothesis or simply a model. Experiments are designed to test the model. Inferential statistics are used to establish a level of confidence in how well our postulated model explains the acquired data. This iterative process, commonly referred to as the scientific method, either improves our confidence in a model or suggests that we revisit our prior knowledge to develop a new model. Advances in technology impact how we use prior knowledge and data to formulate models of biological networks and how we observe cellular behavior. However, the approach for model-based inference has remained largely unchanged since Fisher, Neyman and Pearson developed the ideas in the early 1900’s that gave rise to what is now known as classical statistical hypothesis (model) testing. Here, I will summarize conventional methods for model-based inference and suggest a contemporary approach to aid in our quest to discover how cells dynamically interpret and transmit information for therapeutic aims that integrates ideas drawn from high performance computing, Bayesian statistics, and chemical kinetics. PMID:25139179

  2. [Tests of biological indicators in controling sterilisation processes of autoclaves (author's transl)].

    PubMed

    Holstein, N

    1975-07-01

    For the control of sterilisation processes in autoclaves several biological indicators were examined and compared with native spore samples. The biological indicators were STERIKON (Merck, Darmstadt), KILIT (BBL, USA); the ampulated native spore samples came from Mainz and Berlin, furthermore Bac. subtilis was used on arenaceous quartz. To receive more accurate results and better possibilities for standardization, indicators were not tested in autoclaves but in ultrathermostates. The effect of heat on the viability of ampulated test spores was ascertained by the count of colony formating units on count plates. With two of the tested indicators, KILIT and STERIKON, success of the germicidal process can also be seen by the change of color of the contents of the ampules. Investigations showed ampulated wet spore samples to be totally inefficient, because of their low resistance level, but also suspensios of Bac. subtilis did not meet requirements. Tests of KILIT indicated equally unsatisfactory low levels of heat resistance. Only KTERIKON met the requirements and equalled native spore samples. Since the producer lowered the heat resistance, which was too high initially, by reducing the sowing of spores to 10(2)-10(3) per ml medium of the ampules, the germicidal curve became almost ideal. It has to be mentioned that STERIKON-ampules can only be recommended to ampule-producing-industries. For the control of medicaments in ampules a replacement of native spore samples by STERIKON will only be possible, after the producer has standardized the optimal heat resistance and prevented its decrease while being stored. At present native spore samples are still indispensable - also because they can be widely employed. PMID:811007

  3. Fabrication of mesoscopic floating Si wires by introducing dislocations

    NASA Astrophysics Data System (ADS)

    Motohashi, Mitsuya; Shimizu, Kazuya; Suzuki, Toshiaki; Niwa, Masaaki

    2014-12-01

    We fabricated a mesoscopic Si wire by introducing dislocations in a silicon wafer before HF anodization. The dislocations formed along the (111) crystal plane. The outline of the dislocation line was an inverted triangle. The resulting wire floated on a bridge girder and had a hybrid structure consisting of a porous layer and crystalline Si. The cross section of the wire had an inverted triangle shape. The wire formation mechanism is discussed in terms of carrier transport, crystal structure, and dislocation formation during anodization.

  4. A mesoscopic network model for permanent set in crosslinked elastomers

    SciTech Connect

    Weisgraber, T H; Gee, R H; Maiti, A; Clague, D S; Chinn, S; Maxwell, R S

    2009-01-29

    A mesoscopic computational model for polymer networks and composites is developed as a coarse-grained representation of the composite microstructure. Unlike more complex molecular dynamics simulations, the model only considers the effects of crosslinks on mechanical behavior. The elastic modulus, which depends only on the crosslink density and parameters in the bond potential, is consistent with rubber elasticity theory, and the network response satisfies the independent network hypothesis of Tobolsky. The model, when applied to a commercial filled silicone elastomer, quantitatively reproduces the experimental permanent set and stress-strain response due to changes in the crosslinked network from irradiation.

  5. Two-particle friction in a mesoscopic solvent.

    PubMed

    Lee, Song Hi; Kapral, Raymond

    2005-06-01

    The effects of hydrodynamic interactions on the friction tensors for two particles in solution are studied. The particles have linear dimensions on nanometer scales and are either simple spherical particles interacting with the solvent through repulsive Lennard-Jones forces or are composite cluster particles whose atomic components interact with the solvent through repulsive Lennard-Jones forces. The solvent dynamics is modeled at a mesoscopic level through multiparticle collisions that conserve mass, momentum, and energy. The dependence of the two-particle relative friction tensors on the interparticle separation indicates the importance of hydrodynamic interactions for these nanoparticles. PMID:15974799

  6. Quantum description of a time-dependent mesoscopic RLC circuit

    NASA Astrophysics Data System (ADS)

    Pedrosa, I. A.

    2012-11-01

    In this paper, we present a comprehensive quantum description of a mesoscopic RLC circuit with time-dependent resistance, inductance and capacitance. Based on the dynamical invariant method and using quadratic invariants, we derive exact nonstationary quantum states for this circuit and write them in terms of solutions of the Milne-Pinney equation. Afterwards, we use quadratic invariants to construct coherent states for this quantized system and employ them to investigate quantum properties of the RLC circuit. In particular, we show that the product of the quantum fluctuations of the charge and the magnetic flux does not satisfy the minimum uncertainty relation.

  7. Mesoscopic stoner instability in metallic nanoparticles revealed by shot noise.

    PubMed

    Sothmann, Björn; König, Jürgen; Gefen, Yuval

    2012-04-20

    We study sequential tunneling through a metallic nanoparticle close to the Stoner instability coupled to parallel magnetized electrodes. Increasing the bias voltage successively opens transport channels associated with excitations of the nanoparticle's total spin. For the current this leads just to a steplike increase. The Fano factor, in contrast, shows oscillations between large super-Poissonian and sub-Poissonian values as a function of bias voltage. We explain the enhanced Fano factor in terms of generalized random-telegraph noise and propose the shot noise as a convenient tool to probe the mesoscopic Stoner instability. PMID:22680743

  8. Mesoscopic Simulations of Microfluidic Flow in Irregular Geometries

    NASA Astrophysics Data System (ADS)

    Shendruk, Tyler N.; Slater, Gary W.

    2009-03-01

    Stochastic Rotation Dynamics, a particle-based model for mesoscopic fluid dynamics, is used to study two and three-dimensional flow in a variety of complex boundaries and for a range of low Reynolds numbers (between 10 and 200). The systems considered are of two types: they consist of either irregular geometries such as dimpled pipes or require adaptive boundary conditions such as particle impact on a solid boundary. We apply out techniques to microfluidic devices with complex channel walls such as those used for slalom chromatography and sinusoidal undulation surface patterning chromatography. Numerical results showing good agreement with experimental data and previous computational simulations are presented.

  9. Proximity effect thermometer for local temperature measurements on mesoscopic samples.

    SciTech Connect

    Aumentado, J.; Eom, J.; Chandrasekhar, V.; Baldo, P. M.; Rehn, L. E.; Materials Science Division; Northwestern Univ; Univ. of Chicago

    1999-11-29

    Using the strong temperature-dependent resistance of a normal metal wire in proximity to a superconductor, we have been able to measure the local temperature of electrons heated by flowing a direct-current (dc) in a metallic wire to within a few tens of millikelvin at low temperatures. By placing two such thermometers at different parts of a sample, we have been able to measure the temperature difference induced by a dc flowing in the samples. This technique may provide a flexible means of making quantitative thermal and thermoelectric measurements on mesoscopic metallic samples.

  10. Fabrication and measurement of multi-terminal mesoscopic Josephson junctions

    NASA Astrophysics Data System (ADS)

    Solovyeva, Natalya; Tetsuya, Mishima; Santos, Michael; Shabani, Javad; Manucharyan, Vladimir

    We present fabrication and characterization of 3- and 4-terminal mesoscopic Josephson junctions involving InAs quantum well heterostructures and superconducting Al contacts. A cross-shaped nanowire junction region with dimensions of order a few 100 nm is dry-etched in the 2DEG, followed by deposition of superconducting contacts and gating electrodes. These novel 0D devices have been recently predicted to have topological features in their Andreev spectra and finite-bias transport; they may also be useful in efforts towards observation and braiding of Majorana fermions in the solid state. // This material is based upon work supported by the NSF under Grant No. DMR-1207537.

  11. Biology-inspired microphysiological system approaches to solve the prediction dilemma of substance testing.

    PubMed

    Marx, Uwe; Andersson, Tommy B; Bahinski, Anthony; Beilmann, Mario; Beken, Sonja; Cassee, Flemming R; Cirit, Murat; Daneshian, Mardas; Fitzpatrick, Susan; Frey, Olivier; Gaertner, Claudia; Giese, Christoph; Griffith, Linda; Hartung, Thomas; Heringa, Minne B; Hoeng, Julia; de Jong, Wim H; Kojima, Hajime; Kuehnl, Jochen; Leist, Marcel; Luch, Andreas; Maschmeyer, Ilka; Sakharov, Dmitry; Sips, Adrienne J A M; Steger-Hartmann, Thomas; Tagle, Danilo A; Tonevitsky, Alexander; Tralau, Tewes; Tsyb, Sergej; van de Stolpe, Anja; Vandebriel, Rob; Vulto, Paul; Wang, Jufeng; Wiest, Joachim; Rodenburg, Marleen; Roth, Adrian

    2016-01-01

    The recent advent of microphysiological systems - microfluidic biomimetic devices that aspire to emulate the biology of human tissues, organs and circulation in vitro - is envisaged to enable a global paradigm shift in drug development. An extraordinary US governmental initiative and various dedicated research programs in Europe and Asia have led recently to the first cutting-edge achievements of human single-organ and multi-organ engineering based on microphysiological systems. The expectation is that test systems established on this basis would model various disease stages, and predict toxicity, immunogenicity, ADME profiles and treatment efficacy prior to clinical testing. Consequently, this technology could significantly affect the way drug substances are developed in the future. Furthermore, microphysiological system-based assays may revolutionize our current global programs of prioritization of hazard characterization for any new substances to be used, for example, in agriculture, food, ecosystems or cosmetics, thus, replacing laboratory animal models used currently. Thirty-six experts from academia, industry and regulatory bodies present here the results of an intensive workshop (held in June 2015, Berlin, Germany). They review the status quo of microphysiological systems available today against industry needs, and assess the broad variety of approaches with fit-for-purpose potential in the drug development cycle. Feasible technical solutions to reach the next levels of human biology in vitro are proposed. Furthermore, key organ-on-a-chip case studies, as well as various national and international programs are highlighted. Finally, a roadmap into the future is outlined, to allow for more predictive and regulatory-accepted substance testing on a global scale. PMID:27180100

  12. Mesoscopic imaging of fluorescent proteins using multi-spectral optoacoustic tomography (MSOT)

    NASA Astrophysics Data System (ADS)

    Razansky, Daniel; Vinegoni, Claudio; Ntziachristos, Vasilis

    2009-02-01

    Noninvasive imaging of biological tissues using visible and near-infrared light may provide numerous insights into the underlying morphology or tissue function using a great variety of contrast and probing mechanisms. Nevertheless, mesoscopic-scale (i.e 1mm-1cm sized) living organisms remain largely inaccessible by current optical imaging methods. Depending on the optical properties of a particular object, light diffusion can significantly limit the resolution that can be achieved at depths beyond several hundred microns. To enable in-vivo optical contrast imaging of many important model organisms, such as insects, worms and similarly sized biological specimens, we have developed a multi-spectral optoacoustic tomography technique for high-resolution imaging of optically diffusive organisms and tissues. The method is capable of imaging at depths from sub-millimeter up to a centimeter range with a scalable spatial resolution on the order of magnitude of a few tenths of microns. Furthermore, we show for the first time that the technique is capable of resolving spatial distribution of fluorescent proteins inside intact opaque organisms, thus overcoming depth limitations of current fluorescence microscopy techniques.

  13. "Active" drops as phantom models for living cells: a mesoscopic particle-based approach.

    PubMed

    Dallavalle, Marco; Lugli, Francesca; Rapino, Stefania; Zerbetto, Francesco

    2016-04-13

    Drops and biological cells share some morphological features and visco-elastic properties. The modelling of drops by mesoscopic non-atomistic models has been carried out to a high degree of success in recent years. We extend such treatment and discuss a simple, drop-like model to describe the interactions of the outer layer of cells with the surfaces of materials. Cells are treated as active mechanical objects that are able to generate adhesion forces. They appear with their true size and are made of "parcels of fluids" or beads. The beads are described by (very) few quantities/parameters related to fundamental chemical forces such as hydrophilicity and lipophilicity that represent an average of the properties of a patch of material or an area of the cell(s) surface. The investigation of adhesion dynamics, motion of individual cells, and the collective behavior of clusters of cells on materials is possible. In the simulations, the drops become active soft matter objects and different from regular droplets they do not fuse when in contact, their trajectories are not Brownian, and they can be forced "to secrete" molecules, to name some of the properties targeted by the modeling. The behavior that emerges from the simulations allows ascribing some cell properties to their mechanics, which are related to their biological features. PMID:26890581

  14. Time dependence of mesoscopic strain distribution for triaxial woven carbon-fiber-reinforced polymer under creep loading measured by digital image correlation

    NASA Astrophysics Data System (ADS)

    Koyanagi, Jun; Nagayama, Hideo; Yoneyama, Satoru; Aoki, Takahira

    2016-06-01

    This paper presents the time dependence of the mesoscopic strain of a triaxial woven carbon-fiber-reinforced polymer under creep loading measured using digital image correlation (DIC). Two types of DIC techniques were employed for the measurement: conventional subset DIC and mesh DIC. Static tensile and creep tests were carried out, and the time dependence of the mesoscopic strain distribution was investigated by applying these techniques. The ultimate failure of this material is dominated by inter-bundle decohesion caused by relative rigid rotation and relating shear stress. Therefore, these were focused on in the present study. During the creep tests, the fiber directional strain, shear strain, and rotation were monitored using the DIC, and the mechanism for the increase in the specimen's macro-strain over time was investigated based on the results obtained by the DIC measurement.

  15. Time dependence of mesoscopic strain distribution for triaxial woven carbon-fiber-reinforced polymer under creep loading measured by digital image correlation

    NASA Astrophysics Data System (ADS)

    Koyanagi, Jun; Nagayama, Hideo; Yoneyama, Satoru; Aoki, Takahira

    2016-01-01

    This paper presents the time dependence of the mesoscopic strain of a triaxial woven carbon-fiber-reinforced polymer under creep loading measured using digital image correlation (DIC). Two types of DIC techniques were employed for the measurement: conventional subset DIC and mesh DIC. Static tensile and creep tests were carried out, and the time dependence of the mesoscopic strain distribution was investigated by applying these techniques. The ultimate failure of this material is dominated by inter-bundle decohesion caused by relative rigid rotation and relating shear stress. Therefore, these were focused on in the present study. During the creep tests, the fiber directional strain, shear strain, and rotation were monitored using the DIC, and the mechanism for the increase in the specimen's macro-strain over time was investigated based on the results obtained by the DIC measurement.

  16. The Closed Equilibrated Biological Aquatic System: A 12 months Test of an Artificial Aquatic Ecosystem

    NASA Astrophysics Data System (ADS)

    Blüm, V.; Andriske, M.; Ludwig, Ch.; Paaßen, U.; Voeste, D.

    1999-01-01

    The ``Closed Equilibrated Biological Aquatic System'' (C.E.B.A.S.) is finally disposed for long-term multi-generation experiments with aquatic organisms in a space station. Therefore a minimum operation time of three month is required. It is verified in three versions of laboratory prototypes. The third one passed successfully a 12 months mid-term test in 1995/96 thus demonstrating its high biological stability. The third version of the C.E.B.A.S. consists of a 100 l animal tank, two plant cultivators with a volume of 15 l each with independent illuminations, a 3.0 l semibiological ``mechanical'' filter, a 3.0 l bacteria filter, a heating/cooling device and a dummy filter unit. The live-bearing teleost Xiphophorus helleri is the vertebrate and the pulmonate water snail Biomphalaria glabrata the invertebrate experimental animal in the system. The rootless higher water plant Ceratophyllum demersum is the producer organism. Ammonia oxidizing bacteria and other microorganisms settle in the filters. A simple data acquisition is combined with temperature and plant illumination control. Besides of the space aspects the C.E.B.A.S. proved to be an extremely suitable tool to investigate the organism and subcomponent interactions in a well defined terrestrial aquatic closed ecosystem by providing physical, chemical and biological data which allow an approach to a comprehensive system analysis. Moreover the C.E.B.A.S. is the base for the development of innovative combined animal-plant aquaculture systems for human nutrition on earth which could be implemented into bioregenerative life support systems with a higher degree of complexity suitable for lunar or planetary bases.

  17. Seismoelectric signals produced by mesoscopic heterogeneities: an analytical and numerical study

    NASA Astrophysics Data System (ADS)

    Linde, N.; Rosas Carbajal, M.; Rubino, J. G.; Monachesi, L. B.; Jougnot, D.; Holliger, K.

    2014-12-01

    The presence of mesoscopic heterogeneities, such as fractures, in fluid-saturated porous rocks can produce measurable seismoelectric signals due to wave-induced fluid flow between regions of differing compressibility. Wave-induced fluid flow is a well-known seismic attenuation mechanism, which evidences a strong frequency-dependence that is related to petrophysical and structural properties of the host rock. Therefore, seismoelectric signals arising from this mechanism are expected to depend on the same kind of parameters. However, these remain largely unexplored. In this work, we first propose a numerical approach for computing seismoelectric signals related to the presence of mesoscopic heterogeneities and explore its spectroscopic behavior. To obtain the explicit dependence of the seismoelectric signal on petrophysical and structural parameters, we derive an analytical solution to describe the seismoelectric response of a rock sample containing a horizontal layer at its center that is subjected to an oscillatory compressibility test. We then adapt this general solution to compute the seismoelectric signature of a particular case related to a sample that is permeated by a horizontal fracture. We find that the amplitude of the seismoelectric signal is directly proportional to the applied stress, to the Skempton coefficient contrast between the host rock and the layer, and to a weighted average of the effective excess charge of the two materials. Our results also demonstrate that the frequency at which the maximum electrical potential amplitude prevails is controlled by the permeability and thickness of the less permeable material. The results of this study thus indicate that seismoelectric measurements can potentially be used to estimate key mechanical and hydraulic rock properties, such as compressibility, permeability, and fracture normal compliance.

  18. Unconventional states and geometric effects in mesoscopic systems of ultra-cold atomic Fermi gases

    SciTech Connect

    Bolech, C. J.

    2014-10-15

    During the last decade, experiments all over the world started to test the superconducting state of matter using a newly developed mesoscopic tunable system: trapped ultra-cold atomic gases. Theorists and experimentalists hand-in-hand are now able to advance our understanding of the superconducting state by asking new questions that probe further into the physical mechanisms underlying the phenomenon and the door is open to the exploration of exotic unconventional superconducting states. In particular, a series of experiments on systems of trapped cold atomic gases were aimed at studying the effects of polarization on superconducting pairing. Two different experimental groups encountered surprising qualitative and quantitative discrepancies which seemed to be a function of the confining geometry and the cooling protocol. Our numerical studies demonstrate a tendency towards metastability and suggest an explanation for the observed discrepancy. From our calculations, the most likely solution which is consistent with the experiments supports a state strikingly similar to the so called FFLO state (after Ferrell, Fulde, Larkin and Ovchinnikov), which had been theorized long ago but eluded detection so far. Moreover, the three-dimensional scenario described above is reminiscent of predictions for one-dimensional systems of dilute polarized attractive gases and another set of ultra-cold-atom experiments incorporates optical lattices to study this reduced-dimensionality setting. The measurements are in quantitative agreement with theoretical calculations (using a wide array of numerical and analytic techniques) in which a partially polarized phase is found to be the one-dimensional analogue of the FFLO state. Moreover, exploring the dimensional-crossover regime, our latest findings indicate that the mesoscopic nature of these quasi-one-dimensional systems favors the appearance of a new type of Mott phase transition involving an emergent pair-superfluid of equal

  19. Insight or illusion? Seeing inside the cell with mesoscopic simulations

    PubMed Central

    Shillcock, Julian C.

    2008-01-01

    The expulsion of material from a cell by fusion of vesicles at the plasma membrane, and the entry of a virus by membrane invagination are complex membrane-associated processes whose control is crucial to cell survival. Our ability to visualize the dynamics of such processes experimentally is limited by spatial resolution and the speed of molecular rearrangements. The increase in computing power of the last few decades enables the construction of computational tools for observing cellular processes in silico. As experiments yield increasing amounts of data on the protein and lipid constituents of the cell, computer simulations parametrized using this data are beginning to allow models of cellular processes to be interrogated in ways unavailable in the laboratory. Mesoscopic simulations retain only those molecular features that are believed to be relevant to the processes of interest. This allows the dynamics of spatially heterogeneous membranes and the crowded cytoplasmic environment to be followed at a modest computational cost. The price for such power is that the atomic detail of the constituents is much lower than in atomistic Molecular Dynamics simulations. We argue that this price is worth paying because mesoscopic simulations can generate new insight into the complex, dynamic life of a cell. PMID:19404447

  20. Density functional theory for systems with mesoscopic inhomogeneities

    NASA Astrophysics Data System (ADS)

    Ciach, A.; Gozdz, W. T.

    2016-06-01

    We study the effects of fluctuations on the mesoscopic length scale on systems with mesoscopic inhomogeneities. Equations for the correlation function and for the average volume fraction are derived in the self-consistent Gaussian approximation. The equations are further simplified by postulating the expression for the structure factor consistent with scattering experiments for self-assembling systems. Predictions of the approximate theory are verified by a comparison with the exact results obtained earlier for the one-dimensional lattice model with first-neighbor attraction and third-neighbor repulsion. We find qualitative agreement for the correlation function, the equation of state and the dependence of the chemical potential μ on the volume fraction ζ. Our results confirm also that strong inhomogeneities in the disordered phase are found only in the case of strong repulsion. The inhomogeneities are reflected in an oscillatory decay of the correlation function with a very large correlation length, three inflection points in the μ ≤ft(\\zeta \\right) curve and a compressibility that for increasing ζ takes very large, very small and again very large values.

  1. Density functional theory for systems with mesoscopic inhomogeneities.

    PubMed

    Ciach, A; Gozdz, W T

    2016-06-22

    We study the effects of fluctuations on the mesoscopic length scale on systems with mesoscopic inhomogeneities. Equations for the correlation function and for the average volume fraction are derived in the self-consistent Gaussian approximation. The equations are further simplified by postulating the expression for the structure factor consistent with scattering experiments for self-assembling systems. Predictions of the approximate theory are verified by a comparison with the exact results obtained earlier for the one-dimensional lattice model with first-neighbor attraction and third-neighbor repulsion. We find qualitative agreement for the correlation function, the equation of state and the dependence of the chemical potential μ on the volume fraction ζ. Our results confirm also that strong inhomogeneities in the disordered phase are found only in the case of strong repulsion. The inhomogeneities are reflected in an oscillatory decay of the correlation function with a very large correlation length, three inflection points in the [Formula: see text] curve and a compressibility that for increasing ζ takes very large, very small and again very large values. PMID:27116121

  2. Mesoscopic Fluorescence Molecular Tomography for Evaluating Engineered Tissues.

    PubMed

    Ozturk, Mehmet S; Chen, Chao-Wei; Ji, Robin; Zhao, Lingling; Nguyen, Bao-Ngoc B; Fisher, John P; Chen, Yu; Intes, Xavier

    2016-03-01

    Optimization of regenerative medicine strategies includes the design of biomaterials, development of cell-seeding methods, and control of cell-biomaterial interactions within the engineered tissues. Among these steps, one paramount challenge is to non-destructively image the engineered tissues in their entirety to assess structure, function, and molecular expression. It is especially important to be able to enable cell phenotyping and monitor the distribution and migration of cells throughout the bulk scaffold. Advanced fluorescence microscopic techniques are commonly employed to perform such tasks; however, they are limited to superficial examination of tissue constructs. Therefore, the field of tissue engineering and regenerative medicine would greatly benefit from the development of molecular imaging techniques which are capable of non-destructive imaging of three-dimensional cellular distribution and maturation within a tissue-engineered scaffold beyond the limited depth of current microscopic techniques. In this review, we focus on an emerging depth-resolved optical mesoscopic imaging technique, termed laminar optical tomography (LOT) or mesoscopic fluorescence molecular tomography (MFMT), which enables longitudinal imaging of cellular distribution in thick tissue engineering constructs at depths of a few millimeters and with relatively high resolution. The physical principle, image formation, and instrumentation of LOT/MFMT systems are introduced. Representative applications in tissue engineering include imaging the distribution of human mesenchymal stem cells embedded in hydrogels, imaging of bio-printed tissues, and in vivo applications. PMID:26645079

  3. Theory of Mesoscopic Threshold Detectors of non-Gaussian Noise

    NASA Astrophysics Data System (ADS)

    Jordan, Andrew

    2009-03-01

    Recently, measurements of current fluctuations arising from the charge discreteness (shot noise) have become an invaluable tool in mesoscopic physics, the most noticeable achievement being the measurement of quasi-particle charge in the fractional quantum Hall state. Typically, shot noise experiments report measurements of the zero-frequency noise power, which is a characteristic of the Gaussian component of current fluctuations. A natural generalization of the noise power, the counting statistics of charge transmitted through a system, is interesting in itself, because it contains complete information about the electron transport on a long time scale. However, the measurement of non-Gaussian noise effects presents an experimental challenge because of the limitations imposed by the central limit theorem. This difficulty can be partly overcome by placing an auxiliary mesoscopic system (detector) very close to the noise source and arranging strong coupling to the noise. This leads to the idea of a threshold detector, which is able to measure rare current fluctuations. Its basic principle is analogous to a pole vault: A detection event occurs when the measured system variable exceeds a given threshold value. A natural candidate for such a threshold detector is a metastable system operating on an activation principle. By measuring the rate of switching out of the metastable state, information about the statistical properties of the noise driving the system may be extracted. This requires solving the Kramers' problem of noise-activated escape from a metastable state beyond the Gaussian noise approximation and investigating how the measurement circuit affects threshold detection.

  4. Modeling of mesoscopic electrokinetic phenomena using charged dissipative particle dynamics

    NASA Astrophysics Data System (ADS)

    Deng, Mingge; Li, Zhen; Karniadakis, George

    2015-11-01

    In this work, we propose a charged dissipative particle dynamics (cDPD) model for investigation of mesoscopic electrokinetic phenomena. In particular, this particle-based method was designed to simulate micro- or nano- flows which governing by Poisson-Nernst-Planck (PNP) equation coupled with Navier-Stokes (NS) equation. For cDPD simulations of wall-bounded fluid systems, a methodology for imposing correct Dirichlet and Neumann boundary conditions for both PNP and NS equations is developed. To validate the present cDPD model and the corresponding boundary method, we perform cDPD simulations of electrostatic double layer (EDL) in the vicinity of a charged wall, and the results show good agreement with the mean-field theoretical solutions. The capacity density of a parallel plate capacitor in salt solution is also investigated with different salt concentration. Moreover, we utilize the proposed methodology to study the electroosmotic and electroosmotic/pressure-driven flow in a micro-channel. In the last, we simulate the dilute polyelectrolyte solution both in bulk and micro-channel, which show the flexibility and capability of this method in studying complex fluids. This work was sponsored by the Collaboratory on Mathematics for Mesoscopic Modeling of Materials (CM4) supported by DOE.

  5. Assessment of mesoscopic particle-based methods in microfluidic geometries

    NASA Astrophysics Data System (ADS)

    Zhao, Tongyang; Wang, Xiaogong; Jiang, Lei; Larson, Ronald G.

    2013-08-01

    We assess the accuracy and efficiency of two particle-based mesoscopic simulation methods, namely, Dissipative Particle Dynamics (DPD) and Stochastic Rotation Dynamics (SRD) for predicting a complex flow in a microfluidic geometry. Since both DPD and SRD use soft or weakly interacting particles to carry momentum, both methods contain unavoidable inertial effects and unphysically high fluid compressibility. To assess these effects, we compare the predictions of DPD and SRD for both an exact Stokes-flow solution and nearly exact solutions at finite Reynolds numbers from the finite element method for flow in a straight channel with periodic slip boundary conditions. This flow represents a periodic electro-osmotic flow, which is a complex flow with an analytical solution for zero Reynolds number. We find that SRD is roughly ten-fold faster than DPD in predicting the flow field, with better accuracy at low Reynolds numbers. However, SRD has more severe problems with compressibility effects than does DPD, which limits the Reynolds numbers attainable in SRD to around 25-50, while DPD can achieve Re higher than this before compressibility effects become too large. However, since the SRD method runs much faster than DPD does, we can afford to enlarge the number of grid cells in SRD to reduce the fluid compressibility at high Reynolds number. Our simulations provide a method to estimate the range of conditions for which SRD or DPD is preferable for mesoscopic simulations.

  6. A test of biological trait analysis with nematodes and an anthropogenic stressor.

    PubMed

    Mitwally, Hanan M; Fleeger, John W

    2016-03-01

    Aquatic ecosystems are fundamentally altered by nutrient enrichment, and effective monitoring tools are needed to detect biological responses especially in the early stages of eutrophication. We tested the utility of biological trait analysis (BTA) to quantify the temporal responses of nematodes inhabiting salt marsh creeks that were experimentally enriched with nutrients for 6 years. Feeding, body shape, and tail shape traits were characterized on >6000 nematodes from annual samples from enriched and non-enriched sites. Here, we ask if trait combinations are more effective than single traits in detecting the magnitude and rate of change. We also sought to identify combinations of traits that best distinguish natural from nutrient-induced variation. BTA revealed that feeding, body shape, and all traits combined equally detected the response to nutrient enrichment. Compared to single traits however, BTAs were more sensitive to temporal trends and better distinguished natural variation from the response to nutrient enrichment. Tail shape traits (that might respond to altered sediment texture or geochemistry) were not affected by enrichment, and feeding traits yielded the greatest difference between enriched and reference communities indicating that changes in food resources drove responses. Feeding traits provided the highest quality information content in our study, and the use of feeding traits alone may adequately identify anthropogenic effects in many studies. However, we caution that body shape, tail shape, and feeding traits were strongly interrelated at our study site, and a diversity of trait groups may increase the information content of BTAs in more diverse habitats. PMID:26846290

  7. Persistent Currents and Quantum Critical Phenomena in Mesoscopic Physics

    NASA Astrophysics Data System (ADS)

    Zelyak, Oleksandr

    In this thesis, we study persistent currents and quantum critical phenomena in the systems of mesoscopic physics. As an introduction in Chapter 1 we familiarize the reader with the area of mesoscopic physics. We explain how mesoscopic systems are different from quantum systems of single atoms and molecules and bulk systems with an Avogadro number of elements. We also describe some important mesoscopic phenomena. One of the mathematical tools that we extensively use in our studies is Random Matrix Theorty. This theory is not a part of standard physics courses and for educational purposes we provide the basics of Random Matrix Theory in Chapter 2. In Chapter 3 we study the persistent current of noninteracting electrons in quantum billiards. We consider simply connected chaotic Robnik-Berry quantum billiard and its annular analog. The electrons move in the presence of a point-like magnetic flux at the center of the billiard. For the simply connected billiard, we find a large diamagnetic contribution to the persistent current at small flux, which is independent of the flux and is proportional to the number of electrons (or equivalently the density since we keep the area fixed). The size of this diamagnetic contribution is much larger than the previously studied mesoscopic fluctuations in the persistent current in the simply connected billiard. This behavior of persistent current can ultimately be traced to the response of the angular-momentum l = 0 levels (neglected in semiclassical expansions) on the unit disk to a point-like flux at its center. We observe the same behavior for the annular billiard when the inner radius is much smaller than the outer one. We also find that the usual fluctuating persistent current and Anderson-like localization due to boundary scattering are seen when the annulus tends to a one-dimensional ring. We explore the conditions for the observability of this phenomenon. In Chapter 4 we study quantum critical phenomena in a system of two

  8. Novel Biological Approaches for Testing the Contributions of Single DSBs and DSB Clusters to the Biological Effects of High LET Radiation.

    PubMed

    Mladenova, Veronika; Mladenov, Emil; Iliakis, George

    2016-01-01

    The adverse biological effects of ionizing radiation (IR) are commonly attributed to the generation of DNA double-strand breaks (DSBs). IR-induced DSBs are generated by clusters of ionizations, bear damaged terminal nucleotides, and frequently comprise base damages and single-strand breaks in the vicinity generating a unique DNA damage-clustering effect that increases DSB "complexity." The number of ionizations in clusters of different radiation modalities increases with increasing linear energy transfer (LET), and is thought to determine the long-known LET-dependence of the relative biological effectiveness (RBE). Multiple ionizations may also lead to the formation of DSB clusters, comprising two or more DSBs that destabilize chromatin further and compromise overall processing. DSB complexity and DSB-cluster formation are increasingly considered in the development of mathematical models of radiation action, which are then "tested" by fitting available experimental data. Despite a plethora of such mathematical models the ultimate goal, i.e., the "a priori" prediction of the radiation effect, has not yet been achieved. The difficulty partly arises from unsurmountable difficulties in testing the fundamental assumptions of such mathematical models in defined biological model systems capable of providing conclusive answers. Recently, revolutionary advances in methods allowing the generation of enzymatic DSBs at random or in well-defined locations in the genome, generate unique testing opportunities for several key assumptions frequently fed into mathematical modeling - including the role of DSB clusters in the overall effect. Here, we review the problematic of DSB-cluster formation in radiation action and present novel biological technologies that promise to revolutionize the way we address the biological consequences of such lesions. We describe new ways of exploiting the I-SceI endonuclease to generate DSB-clusters at random locations in the genome and describe the

  9. Epistemological Predictors of "Self Efficacy on Learning Biology" and "Test Anxiety Related to Evaluation of Learning on Biology" for Pre-service Elementary Teachers

    NASA Astrophysics Data System (ADS)

    Köksal, Mustafa Serdar

    2011-11-01

    The degree to which pre-service teachers learn biology is related to both motivational factors of self-regulation and factors regarding epistemological beliefs. At the same time, self-regulation and epistemological beliefs are also associated with one another. Based on this relationship, the purpose of this study was to investigate the relationship between components of epistemological beliefs and self-refulation (self-efficacy and test-anxiety) on learning biology. The study was conducted with 411 pre-service elementary and pre-service elementary science teachers by using a predictive research approach. Collected data was analyzed by the multiple linear regression technique. The results showed that only the belief about "existence of one truth" was a significant predictor of test anxiety while there was no epistemological predictor of self-efficacy. Conclusions and implications of the study will be discussed.

  10. Non-markovian mesoscopic dissipative dynamics of open quantum spin chains

    NASA Astrophysics Data System (ADS)

    Benatti, F.; Carollo, F.; Floreanini, R.; Narnhofer, H.

    2016-01-01

    We study the dissipative dynamics of N quantum spins with Lindblad generator consisting of operators scaling as fluctuations, namely with the inverse square-root of N. In the large N limit, the microscopic dissipative time-evolution converges to a non-Markovian unitary dynamics on strictly local operators, while at the mesoscopic level of fluctuations it gives rise to a dissipative non-Markovian dynamics. The mesoscopic time-evolution is Gaussian and exhibits either a stable or an unstable asymptotic character; furthermore, the mesoscopic dynamics builds correlations among fluctuations that survive in time even when the original microscopic dynamics is unable to correlate local observables.

  11. Novel Biological Approaches for Testing the Contributions of Single DSBs and DSB Clusters to the Biological Effects of High LET Radiation

    PubMed Central

    Mladenova, Veronika; Mladenov, Emil; Iliakis, George

    2016-01-01

    The adverse biological effects of ionizing radiation (IR) are commonly attributed to the generation of DNA double-strand breaks (DSBs). IR-induced DSBs are generated by clusters of ionizations, bear damaged terminal nucleotides, and frequently comprise base damages and single-strand breaks in the vicinity generating a unique DNA damage-clustering effect that increases DSB “complexity.” The number of ionizations in clusters of different radiation modalities increases with increasing linear energy transfer (LET), and is thought to determine the long-known LET-dependence of the relative biological effectiveness (RBE). Multiple ionizations may also lead to the formation of DSB clusters, comprising two or more DSBs that destabilize chromatin further and compromise overall processing. DSB complexity and DSB-cluster formation are increasingly considered in the development of mathematical models of radiation action, which are then “tested” by fitting available experimental data. Despite a plethora of such mathematical models the ultimate goal, i.e., the “a priori” prediction of the radiation effect, has not yet been achieved. The difficulty partly arises from unsurmountable difficulties in testing the fundamental assumptions of such mathematical models in defined biological model systems capable of providing conclusive answers. Recently, revolutionary advances in methods allowing the generation of enzymatic DSBs at random or in well-defined locations in the genome, generate unique testing opportunities for several key assumptions frequently fed into mathematical modeling – including the role of DSB clusters in the overall effect. Here, we review the problematic of DSB-cluster formation in radiation action and present novel biological technologies that promise to revolutionize the way we address the biological consequences of such lesions. We describe new ways of exploiting the I-SceI endonuclease to generate DSB-clusters at random locations in the genome and

  12. Testing surrogacy assumptions: can threatened and endangered plants be grouped by biological similarity and abundances?

    PubMed

    Che-Castaldo, Judy P; Neel, Maile C

    2012-01-01

    There is renewed interest in implementing surrogate species approaches in conservation planning due to the large number of species in need of management but limited resources and data. One type of surrogate approach involves selection of one or a few species to represent a larger group of species requiring similar management actions, so that protection and persistence of the selected species would result in conservation of the group of species. However, among the criticisms of surrogate approaches is the need to test underlying assumptions, which remain rarely examined. In this study, we tested one of the fundamental assumptions underlying use of surrogate species in recovery planning: that there exist groups of threatened and endangered species that are sufficiently similar to warrant similar management or recovery criteria. Using a comprehensive database of all plant species listed under the U.S. Endangered Species Act and tree-based random forest analysis, we found no evidence of species groups based on a set of distributional and biological traits or by abundances and patterns of decline. Our results suggested that application of surrogate approaches for endangered species recovery would be unjustified. Thus, conservation planning focused on individual species and their patterns of decline will likely be required to recover listed species. PMID:23240051

  13. Dosimetric and biological results from the Bacillus subtilis Biostack experiment with the Apollo-Soyuz Test Project.

    PubMed

    Facius, R; Bucker, H; Horneck, G; Reitz, G; Schafer, M

    1979-01-01

    The evaluation of the Bacillus subtilis experiment has been completed. The biological and the physical results for this part of the Apollo-Soyuz Test Project (ASTP) Biostack experiment are given. This comprises dosimetric data for the cosmic radiation at that orbit as well as biological findings from two types of plastic detectors. Further, the frequency distributions of the physical quantities atomic number, energy and energy loss of the heavy ions within the sample of spores hit are presented. The biological hazard presented by cosmic HZE-particles has been much underestimated. PMID:12001965

  14. Simulating mesoscopic reaction-diffusion systems using the Gillespie algorithm

    SciTech Connect

    Bernstein, David

    2004-12-12

    We examine an application of the Gillespie algorithm to simulating spatially inhomogeneous reaction-diffusion systems in mesoscopic volumes such as cells and microchambers. The method involves discretizing the chamber into elements and modeling the diffusion of chemical species by the movement of molecules between neighboring elements. These transitions are expressed in the form of a set of reactions which are added to the chemical system. The derivation of the rates of these diffusion reactions is by comparison with a finite volume discretization of the heat equation on an unevenly spaced grid. The diffusion coefficient of each species is allowed to be inhomogeneous in space, including discontinuities. The resulting system is solved by the Gillespie algorithm using the fast direct method. We show that in an appropriate limit the method reproduces exact solutions of the heat equation for a purely diffusive system and the nonlinear reaction-rate equation describing the cubic autocatalytic reaction.

  15. Simulating mesoscopic reaction-diffusion systems using the Gillespie algorithm.

    PubMed

    Bernstein, David

    2005-04-01

    We examine an application of the Gillespie algorithm to simulating spatially inhomogeneous reaction-diffusion systems in mesoscopic volumes such as cells and microchambers. The method involves discretizing the chamber into elements and modeling the diffusion of chemical species by the movement of molecules between neighboring elements. These transitions are expressed in the form of a set of reactions which are added to the chemical system. The derivation of the rates of these diffusion reactions is by comparison with a finite volume discretization of the heat equation on an unevenly spaced grid. The diffusion coefficient of each species is allowed to be inhomogeneous in space, including discontinuities. The resulting system is solved by the Gillespie algorithm using the fast direct method. We show that in an appropriate limit the method reproduces exact solutions of the heat equation for a purely diffusive system and the nonlinear reaction-rate equation describing the cubic autocatalytic reaction. PMID:15903653

  16. Acoustic dynamics of network-forming glasses at mesoscopic wavelengths.

    PubMed

    Ferrante, C; Pontecorvo, E; Cerullo, G; Chiasera, A; Ruocco, G; Schirmacher, W; Scopigno, T

    2013-01-01

    The lack of long-range structural order in amorphous solids induces well known thermodynamic anomalies, which are the manifestation of distinct peculiarities in the vibrational spectrum. Although the impact of such anomalies vanishes in the long wavelength, elastic continuum limit, it dominates at length scales comparable to interatomic distances, implying an intermediate transition regime still poorly understood. Here we report a study of such mesoscopic domains by means of a broadband version of picosecond photo-acoustics, developed to coherently generate and detect hypersonic sound waves in the sub-THz region with unprecedented sampling efficiency. We identify a temperature-dependent fractal v(3/2) frequency behaviour of the sound attenuation, pointing to the presence of marginally stable regions and a transition between the two above mentioned limits. The essential features of this behaviour are captured by a theoretical approach based on random spatial variation of the shear modulus, including anharmonic interactions. PMID:23653205

  17. Acoustic dynamics of network-forming glasses at mesoscopic wavelengths

    PubMed Central

    Ferrante, C.; Pontecorvo, E.; Cerullo, G.; Chiasera, A.; Ruocco, G.; Schirmacher, W.; Scopigno, T.

    2013-01-01

    The lack of long-range structural order in amorphous solids induces well known thermodynamic anomalies, which are the manifestation of distinct peculiarities in the vibrational spectrum. Although the impact of such anomalies vanishes in the long wavelength, elastic continuum limit, it dominates at length scales comparable to interatomic distances, implying an intermediate transition regime still poorly understood. Here we report a study of such mesoscopic domains by means of a broadband version of picosecond photo-acoustics, developed to coherently generate and detect hypersonic sound waves in the sub-THz region with unprecedented sampling efficiency. We identify a temperature-dependent fractal v3/2 frequency behaviour of the sound attenuation, pointing to the presence of marginally stable regions and a transition between the two above mentioned limits. The essential features of this behaviour are captured by a theoretical approach based on random spatial variation of the shear modulus, including anharmonic interactions. PMID:23653205

  18. Mesoscopic Patterns of Neural Activity Support Songbird Cortical Sequences

    PubMed Central

    Guitchounts, Grigori; Velho, Tarciso; Lois, Carlos; Gardner, Timothy J.

    2015-01-01

    Time-locked sequences of neural activity can be found throughout the vertebrate forebrain in various species and behavioral contexts. From “time cells” in the hippocampus of rodents to cortical activity controlling movement, temporal sequence generation is integral to many forms of learned behavior. However, the mechanisms underlying sequence generation are not well known. Here, we describe a spatial and temporal organization of the songbird premotor cortical microcircuit that supports sparse sequences of neural activity. Multi-channel electrophysiology and calcium imaging reveal that neural activity in premotor cortex is correlated with a length scale of 100 µm. Within this length scale, basal-ganglia–projecting excitatory neurons, on average, fire at a specific phase of a local 30 Hz network rhythm. These results show that premotor cortical activity is inhomogeneous in time and space, and that a mesoscopic dynamical pattern underlies the generation of the neural sequences controlling song. PMID:26039895

  19. Chirality in block copolymer melts: mesoscopic helicity from intersegment twist.

    PubMed

    Zhao, Wei; Russell, Thomas P; Grason, Gregory M

    2013-02-01

    We study the effects of chirality at the segment scale on the thermodynamics of block copolymer melts using self-consistent field theory. In linear diblock melts where segments of one block prefer a twisted, or cholesteric, texture, we show that melt assembly is critically sensitive to the ratio of random coil size to the preferred pitch of cholesteric twist. For weakly chiral melts (large pitch), mesophases remain achiral, while below a critical value of pitch, two mesoscopically chiral phases are stable: an undulated lamellar phase and a phase of hexagonally ordered helices. We show that the nonlinear sensitivity of mesoscale chiral order to preferred pitch derives specifically from the geometric and thermodynamic coupling of the helical mesodomain shape to the twisted packing of chiral segments within the core, giving rise to a second-order cylinder-to-helix transition. PMID:23414052

  20. Mesoscopic mechanical resonators as quantum noninertial reference frames

    NASA Astrophysics Data System (ADS)

    Katz, B. N.; Blencowe, M. P.; Schwab, K. C.

    2015-10-01

    An atom attached to a micrometer-scale wire that is vibrating at a frequency ˜100 MHz and with displacement amplitude ˜1 nm experiences an acceleration magnitude ˜109ms -2 , approaching the surface gravity of a neutron star. As one application of such extreme noninertial forces in a mesoscopic setting, we consider a model two-path atom interferometer with one path consisting of the 100 MHz vibrating wire atom guide. The vibrating wire guide serves as a noninertial reference frame and induces an in principle measurable phase shift in the wave function of an atom traversing the wire frame. We furthermore consider the effect on the two-path atom wave interference when the vibrating wire is modeled as a quantum object, hence functioning as a quantum noninertial reference frame. We outline a possible realization of the vibrating wire, atom interferometer using a superfluid helium quantum interference setup.

  1. Magnetostatic interactions in mesoscopic Ni80Fe20 ring arrays

    NASA Astrophysics Data System (ADS)

    Wang, J.; Adeyeye, A. O.; Singh, N.

    2005-12-01

    We investigate, directly using magnetic force microscopy, the effect of magnetostatic interactions in arrays of Ni80Fe20 mesoscopic rings. The rings were fabricated on silicon substrate using deep ultraviolet lithography at 248 nm exposure wavelength. We observed that the transitions from onion-to-vortex and vortex-to-reverse onion magnetic states are strongly dependent on the edge-to-edge-spacing of the rings due to dipolar magnetostatic interaction. For a closely packed ring array, the transition from onion to vortex state occurs at a much lower field due to collective magnetic switching as compared with widely spaced rings. The remanent magnetic state is found to be very sensitive to the orientation of the applied field due to shape anisotropy.

  2. Imaging coherent transport in a mesoscopic graphene ring

    NASA Astrophysics Data System (ADS)

    Cabosart, Damien; Faniel, Sébastien; Martins, Frederico; Brun, Boris; Felten, Alexandre; Bayot, Vincent; Hackens, Benoit

    2014-11-01

    Mesoscopic graphene devices often exhibit complex transport properties, stemming both from the peculiar electronic band structure of graphene and from the high sensitivity of transport to local disorder in this two-dimensional crystal. To disentangle contributions of disorder in the different transport phenomena at play in such devices, it is necessary to devise new local-probe methods and to establish links between transport and the microscopic structure of the devices. Here, we present a spatially resolved investigation of coherent transport inside a graphene quantum ring (QR), where Aharonov-Bohm conductance oscillations are observed. Thanks to scanning gate microscopy (SGM), we first identify spatial signatures of the Coulomb blockade, associated with disorder-induced localized states, and of charge-carrier interferences. We then image resonant states which decorate the QR local density of states (LDOS). Simulations of the LDOS in a model disorder graphene QR and temperature dependence of SGM maps confirm the presence of such scarred states.

  3. Manipulating mesoscopic multipartite entanglement with atom-light interfaces

    SciTech Connect

    Stasinska, J.; Rodo, C.; Paganelli, S.; Birkl, G.; Sanpera, A.

    2009-12-15

    Entanglement between two macroscopic atomic ensembles induced by measurement on an ancillary light system has proven to be a powerful method for engineering quantum memories and quantum state transfer. Here we investigate the feasibility of such methods for generation, manipulation, and detection of genuine multipartite entanglement (Greenberger-Horne-Zeilinger and clusterlike states) between mesoscopic atomic ensembles without the need of individual addressing of the samples. Our results extend in a nontrivial way the Einstein-Podolsky-Rosen entanglement between two macroscopic gas samples reported experimentally in [B. Julsgaard, A. Kozhekin, and E. Polzik, Nature (London) 413, 400 (2001)]. We find that under realistic conditions, a second orthogonal light pulse interacting with the atomic samples, can modify and even reverse the entangling action of the first one leaving the samples in a separable state.

  4. Mesoscopic resonating valence bond system on a triple dot.

    PubMed

    Le Hur, Karyn; Recher, Patrik; Dupont, Emilie; Loss, Daniel

    2006-03-17

    We theoretically introduce a mesoscopic pendulum from a triple dot. The pendulum is fastened through a singly occupied dot (spin qubit). Two other strongly capacitively coupled islands form a double-dot charge qubit with one electron in excess oscillating between the two low-energy charge states (1,0) and (0,1). The triple dot is placed between two superconducting leads. Under realistic conditions, the main proximity effect stems from the injection of resonating singlet (valence) bonds on the triple dot. This gives rise to a Josephson current that is charge- and spin-dependent and, as a consequence, exhibits a distinct resonance as a function of the superconducting phase difference. PMID:16605773

  5. Mesoscopic patterns of neural activity support songbird cortical sequences.

    PubMed

    Markowitz, Jeffrey E; Liberti, William A; Guitchounts, Grigori; Velho, Tarciso; Lois, Carlos; Gardner, Timothy J

    2015-06-01

    Time-locked sequences of neural activity can be found throughout the vertebrate forebrain in various species and behavioral contexts. From "time cells" in the hippocampus of rodents to cortical activity controlling movement, temporal sequence generation is integral to many forms of learned behavior. However, the mechanisms underlying sequence generation are not well known. Here, we describe a spatial and temporal organization of the songbird premotor cortical microcircuit that supports sparse sequences of neural activity. Multi-channel electrophysiology and calcium imaging reveal that neural activity in premotor cortex is correlated with a length scale of 100 µm. Within this length scale, basal-ganglia-projecting excitatory neurons, on average, fire at a specific phase of a local 30 Hz network rhythm. These results show that premotor cortical activity is inhomogeneous in time and space, and that a mesoscopic dynamical pattern underlies the generation of the neural sequences controlling song. PMID:26039895

  6. Mesoscopic Josephson junctions with switchable current-phase relation

    NASA Astrophysics Data System (ADS)

    Strambini, E.; Bergeret, F. S.; Giazotto, F.

    2015-10-01

    We propose and analyze a mesoscopic Josephson junction consisting of two ferromagnetic insulator-superconductors (FI-Ss) coupled through a normal metal (N) layer. The Josephson current of the junction is non-trivially affected by the spin-splitting field induced by the FIs in the two superconductors. In particular, it shows sizeable enhancement by increasing the amplitude of the exchange field (hex) and displays a switchable current-phase relation which depends on the relative orientation of h ex in the FIs. In a realistic EuS/Al-based setup this junction can be exploited as a high-resolution threshold sensor for the magnetic field as well as an on-demand tunable kinetic inductor.

  7. Electron teleportation via Majorana bound states in a mesoscopic superconductor.

    PubMed

    Fu, Liang

    2010-02-01

    Zero-energy Majorana bound states in superconductors have been proposed to be potential building blocks of a topological quantum computer, because quantum information can be encoded nonlocally in the fermion occupation of a pair of spatially separated Majorana bound states. However, despite intensive efforts, nonlocal signatures of Majorana bound states have not been found in charge transport. In this work, we predict a striking nonlocal phase-coherent electron transfer process by virtue of tunneling in and out of a pair of Majorana bound states. This teleportation phenomenon only exists in a mesoscopic superconductor because of an all-important but previously overlooked charging energy. We propose an experimental setup to detect this phenomenon in a superconductor-quantum-spin-Hall-insulator-magnetic-insulator hybrid system. PMID:20366777

  8. Interfacial nanorheology: Probing molecular mobility in mesoscopic polymeric systems

    NASA Astrophysics Data System (ADS)

    Sills, Scott E.

    Investigating the finite size limited structural relaxations in mesoscopic polymer systems is central to nanotechnological applications involving thin films, complex structures, and nanoscale phase-separated systems; for example, polymer electrolyte membranes, optoelectronic devices, and ultrahigh-density thermomechanical data storage (terabit recording). In such systems, bulk statistical averaging and continuum models are jeopardized. Interfacial constraints lead to bulk-deviating molecular dynamics and dictate material and transport properties. The objective of this dissertation is to provide insight to the exotic mesoscopic behaviors in thin films by developing novel rheological and tribological analytical methods based on scanning probe microscopy (SPM). Activation energies are deduced for the molecular motions associated with internal friction dissipation, and the temperature resolved length scale for cooperative motion during the glass transition is directly obtained for polystyrene. These results confirm the dynamical heterogeneity of the glass transition and reveal a crossover from intra- to inter-molecular relaxation in the transition regime. The impact of dimensional constraints on molecular mobility in ultrathin polymer films is explored through interfacial glass-transition profiles. With these profiles, a structural model of the rheological changes near interfacial boundaries is constructed as function of molecular weight and crosslinking density. The manifestation of interfacial constraints in nanotechnological applications is illustrated for thermomechanical recording, where rheological gradients near the substrate dictate the contact pressure and strain shielding at the substrate compromises film stability. A foundation for the critical aspects of interfacial stability is developed, and mechanically graded interfaces and modulus-matching techniques are explored as a means of improving the stability, durability, and stress transmission characteristics

  9. Hearing Tests on Mobile Devices: Evaluation of the Reference Sound Level by Means of Biological Calibration

    PubMed Central

    Kipiński, Lech; Grysiński, Tomasz; Kręcicki, Tomasz

    2016-01-01

    Background Hearing tests carried out in home setting by means of mobile devices require previous calibration of the reference sound level. Mobile devices with bundled headphones create a possibility of applying the predefined level for a particular model as an alternative to calibrating each device separately. Objective The objective of this study was to determine the reference sound level for sets composed of a mobile device and bundled headphones. Methods Reference sound levels for Android-based mobile devices were determined using an open access mobile phone app by means of biological calibration, that is, in relation to the normal-hearing threshold. The examinations were conducted in 2 groups: an uncontrolled and a controlled one. In the uncontrolled group, the fully automated self-measurements were carried out in home conditions by 18- to 35-year-old subjects, without prior hearing problems, recruited online. Calibration was conducted as a preliminary step in preparation for further examination. In the controlled group, audiologist-assisted examinations were performed in a sound booth, on normal-hearing subjects verified through pure-tone audiometry, recruited offline from among the workers and patients of the clinic. In both the groups, the reference sound levels were determined on a subject’s mobile device using the Bekesy audiometry. The reference sound levels were compared between the groups. Intramodel and intermodel analyses were carried out as well. Results In the uncontrolled group, 8988 calibrations were conducted on 8620 different devices representing 2040 models. In the controlled group, 158 calibrations (test and retest) were conducted on 79 devices representing 50 models. Result analysis was performed for 10 most frequently used models in both the groups. The difference in reference sound levels between uncontrolled and controlled groups was 1.50 dB (SD 4.42). The mean SD of the reference sound level determined for devices within the same model

  10. Mesoscopic model and free energy landscape for protein-DNA binding sites: analysis of cyanobacterial promoters.

    PubMed

    Tapia-Rojo, Rafael; Mazo, Juan José; Hernández, José Ángel; Peleato, María Luisa; Fillat, María F; Falo, Fernando

    2014-10-01

    The identification of protein binding sites in promoter sequences is a key problem to understand and control regulation in biochemistry and biotechnological processes. We use a computational method to analyze promoters from a given genome. Our approach is based on a physical model at the mesoscopic level of protein-DNA interaction based on the influence of DNA local conformation on the dynamics of a general particle along the chain. Following the proposed model, the joined dynamics of the protein particle and the DNA portion of interest, only characterized by its base pair sequence, is simulated. The simulation output is analyzed by generating and analyzing the Free Energy Landscape of the system. In order to prove the capacity of prediction of our computational method we have analyzed nine promoters of Anabaena PCC 7120. We are able to identify the transcription starting site of each of the promoters as the most populated macrostate in the dynamics. The developed procedure allows also to characterize promoter macrostates in terms of thermo-statistical magnitudes (free energy and entropy), with valuable biological implications. Our results agree with independent previous experimental results. Thus, our methods appear as a powerful complementary tool for identifying protein binding sites in promoter sequences. PMID:25275384

  11. Imaging of mesoscopic-scale organisms using selective-plane optoacoustic tomography

    NASA Astrophysics Data System (ADS)

    Razansky, Daniel; Vinegoni, Claudio; Ntziachristos, Vasilis

    2009-05-01

    Mesoscopic-scale living organisms (i.e. 1 mm to 1 cm sized) remain largely inaccessible by current optical imaging methods due to intensive light scattering in tissues. Therefore, imaging of many important model organisms, such as insects, fishes, worms and similarly sized biological specimens, is currently limited to embryonic or other transparent stages of development. This makes it difficult to relate embryonic cellular and molecular mechanisms to consequences in organ function and animal behavior in more advanced stages and adults. Herein, we have developed a selective-plane illumination optoacoustic tomography technique for in vivo imaging of optically diffusive organisms and tissues. The method is capable of whole-body imaging at depths from the sub-millimeter up to centimeter range with a scalable spatial resolution in the order of magnitude of a few tenths of microns. In contrast to pure optical methods, the spatial resolution here is not determined nor limited by light diffusion; therefore, such performance cannot be achieved by any other optical imaging technology developed so far. The utility of the method is demonstrated on several whole-body models and small-animal extremities.

  12. Mesoscopic Model and Free Energy Landscape for Protein-DNA Binding Sites: Analysis of Cyanobacterial Promoters

    PubMed Central

    Tapia-Rojo, Rafael; Mazo, Juan José; Hernández, José Ángel; Peleato, María Luisa; Fillat, María F.; Falo, Fernando

    2014-01-01

    The identification of protein binding sites in promoter sequences is a key problem to understand and control regulation in biochemistry and biotechnological processes. We use a computational method to analyze promoters from a given genome. Our approach is based on a physical model at the mesoscopic level of protein-DNA interaction based on the influence of DNA local conformation on the dynamics of a general particle along the chain. Following the proposed model, the joined dynamics of the protein particle and the DNA portion of interest, only characterized by its base pair sequence, is simulated. The simulation output is analyzed by generating and analyzing the Free Energy Landscape of the system. In order to prove the capacity of prediction of our computational method we have analyzed nine promoters of Anabaena PCC 7120. We are able to identify the transcription starting site of each of the promoters as the most populated macrostate in the dynamics. The developed procedure allows also to characterize promoter macrostates in terms of thermo-statistical magnitudes (free energy and entropy), with valuable biological implications. Our results agree with independent previous experimental results. Thus, our methods appear as a powerful complementary tool for identifying protein binding sites in promoter sequences. PMID:25275384

  13. Nature of Mesoscopic Organization in Protic Ionic Liquid-Alcohol Mixtures.

    PubMed

    Schroer, Wolffram; Triolo, Alessandro; Russina, Olga

    2016-03-10

    The mesoscopic morphology of mixtures of ethylammonium nitrate, a protic ionic liquid, and n-pentanol is explored for the first time using small angle X-ray scattering as a function of concentration and temperature. Both compounds are amphiphilic and characterized by an extended hydrogen bonding network; however, though macroscopically homogeneous, their mixtures are highly heterogeneous at the mesoscopic spatial scales. Previous structural studies rationalized similar features in related mixtures proposing the existence of large aggregates or micelle- and/or microemulsion-like structures. Here we show that a detailed analysis of the present concentration and temperature resolved experimental data set supports a structural scenario where the mesoscopic heterogeneities are the due to density fluctuations that are precursors of liquid-liquid phase separation. Accordingly no existence of structurally organized aggregates (such as micellar or microemulsion aggregates) is required to account for the mesoscopic heterogeneities detected in this class of binary mixtures. PMID:26895177

  14. Advances in design and testing of limited angle optical diffraction tomographysystem for biological applications

    NASA Astrophysics Data System (ADS)

    Kuś, A.; Makowski, P.; Kujawińska, M.

    2016-03-01

    Optical diffraction tomography has been steadily proving its potential to study one of the hot topics in modern cell biology -- 3D dynamic changes in cells' morphology represented with refractive index values. In this technique digital holography is combined with tomographic reconstruction and thus it is necessary to provide projections acquired at different viewing directions. Usually the Mach-Zehnder interferometer configuration is used and while the object beam performs scanning, the reference beam is in most cases stationary. This approach either limits possible scanning strategies or requires additional mechanical movement to be introduced in the reference beam. On the other hand, spiral or grid scanning is possible in alternative common-path or Michelson configurations. However, in this case there is no guarantee that a specimen is sparse enough for the object to interfere with an object-free part of the beam. In this paper we present a modified version of Mach-Zehnder interferometer-based tomographic microscope, in which both object and reference beam are subject to scanning using one scanning device only thus making any scanning scenario possible. This concept is realized with a custom-built optical system in the reference beam and is appropriate for mechanical as well as optical scanning. Usually, the tomographic reconstruction setups and algorithms are verified using a microsphere phantom, which is not enough to test the influence of the distribution of the projections. In this work we propose a more complex calibration object created using two-photon polymerization.

  15. Examples of testing global identifiability of biological and biomedical models with the DAISY software.

    PubMed

    Saccomani, Maria Pia; Audoly, Stefania; Bellu, Giuseppina; D'Angiò, Leontina

    2010-04-01

    DAISY (Differential Algebra for Identifiability of SYstems) is a recently developed computer algebra software tool which can be used to automatically check global identifiability of (linear and) nonlinear dynamic models described by differential equations involving polynomial or rational functions. Global identifiability is a fundamental prerequisite for model identification which is important not only for biological or medical systems but also for many physical and engineering systems derived from first principles. Lack of identifiability implies that the parameter estimation techniques may not fail but any obtained numerical estimates will be meaningless. The software does not require understanding of the underlying mathematical principles and can be used by researchers in applied fields with a minimum of mathematical background. We illustrate the DAISY software by checking the a priori global identifiability of two benchmark nonlinear models taken from the literature. The analysis of these two examples includes comparison with other methods and demonstrates how identifiability analysis is simplified by this tool. Thus we illustrate the identifiability analysis of other two examples, by including discussion of some specific aspects related to the role of observability and knowledge of initial conditions in testing identifiability and to the computational complexity of the software. The main focus of this paper is not on the description of the mathematical background of the algorithm, which has been presented elsewhere, but on illustrating its use and on some of its more interesting features. DAISY is available on the web site http://www.dei.unipd.it/ approximately pia/. PMID:20185123

  16. High Resolution Higher Energy X-ray Microscope for Mesoscopic Materials

    NASA Astrophysics Data System (ADS)

    Snigireva, I.; Snigirev, A.

    2013-10-01

    We developed a novel X-ray microscopy technique to study mesoscopically structured materials, employing compound refractive lenses. The easily seen advantage of lens-based methodology is the possibility to retrieve high resolution diffraction pattern and real-space images in the same experimental setup. Methodologically the proposed approach is similar to the studies of crystals by high resolution transmission electron microscopy. The proposed microscope was applied for studying of mesoscopic materials such as natural and synthetic opals, inverted photonic crystals.

  17. Quantum fluctuations in mesoscopic systems: II, Summary of previous research: Progress report, 1990--1991

    SciTech Connect

    Not Available

    1991-01-01

    This summarizes results from the current DOE funding period (9/88--9/91). Analytical results are presented on the subject of the universal conductance fluctuations in mesoscopic conductors, in particular the connection with low temperature 1/F noise magnitudes in disordered systems. Novel correlations in laser speckle patterns are discussed. And other results on the quantum transport in mesoscopic electronic systems are described. (GHH)

  18. Quantum fluctuations in mesoscopic systems: II, Summary of previous research: Progress report, 1990--1991

    SciTech Connect

    Not Available

    1991-12-31

    This summarizes results from the current DOE funding period (9/88--9/91). Analytical results are presented on the subject of the universal conductance fluctuations in mesoscopic conductors, in particular the connection with low temperature 1/F noise magnitudes in disordered systems. Novel correlations in laser speckle patterns are discussed. And other results on the quantum transport in mesoscopic electronic systems are described. (GHH)

  19. Modelling and control strategy testing of biological and chemical phosphorus removal at Avedøre WWTP.

    PubMed

    Ingildsen, P; Rosen, C; Gernaey, K V; Nielsen, M K; Guildal, T; Jacobsen, B N

    2006-01-01

    The biological phosphorus removal process is often implemented at plants by the construction of an anaerobic bio-p tank in front of the traditional N removing plant configuration. However, biological phosphorus removal is also observed in plant configurations constructed only for nitrogen removal and simultaneous or post-precipitation. The operational experience with this "accidental" biological phosphorus removal is often mixed with quite a lot of frustration, as the process seems to come and go and hence behaves quite uncontrollably. The aim of this work is to develop ways of intentionally exploiting the biological phosphorus process by the use of instrumentation, control and automation to reduce the consumption of precipitants. Means to this end are first to calibrate a modified ASM2d model to a full-scale wastewater treatment plant (WWTP), including both biological and chemical phosphorus removal and a model of the sedimentation process. Second, based on the calibrated model a benchmark model is developed and various control strategies for biological phosphorus removal are tested. Experiences and knowledge gained from the strategies presented and discussed in this paper are vital inputs for the full-scale implementation of a control strategy for biological phosphorus removal at Avedøre WWTP, which is described in another paper. The two papers hence show a way to bridge the gap from model to full implementation. PMID:16722060

  20. Space experiment "Cellular Responses to Radiation in Space (CELLRAD)": Hardware and biological system tests

    NASA Astrophysics Data System (ADS)

    Hellweg, Christine E.; Dilruba, Shahana; Adrian, Astrid; Feles, Sebastian; Schmitz, Claudia; Berger, Thomas; Przybyla, Bartos; Briganti, Luca; Franz, Markus; Segerer, Jürgen; Spitta, Luis F.; Henschenmacher, Bernd; Konda, Bikash; Diegeler, Sebastian; Baumstark-Khan, Christa; Panitz, Corinna; Reitz, Günther

    2015-11-01

    One factor contributing to the high uncertainty in radiation risk assessment for long-term space missions is the insufficient knowledge about possible interactions of radiation with other spaceflight environmental factors. Such factors, e.g. microgravity, have to be considered as possibly additive or even synergistic factors in cancerogenesis. Regarding the effects of microgravity on signal transduction, it cannot be excluded that microgravity alters the cellular response to cosmic radiation, which comprises a complex network of signaling pathways. The purpose of the experiment "Cellular Responses to Radiation in Space" (CELLRAD, formerly CERASP) is to study the effects of combined exposure to microgravity, radiation and general space flight conditions on mammalian cells, in particular Human Embryonic Kidney (HEK) cells that are stably transfected with different plasmids allowing monitoring of proliferation and the Nuclear Factor κB (NF-κB) pathway by means of fluorescent proteins. The cells will be seeded on ground in multiwell plate units (MPUs), transported to the ISS, and irradiated by an artificial radiation source after an adaptation period at 0 × g and 1 × g. After different incubation periods, the cells will be fixed by pumping a formaldehyde solution into the MPUs. Ground control samples will be treated in the same way. For implementation of CELLRAD in the Biolab on the International Space Station (ISS), tests of the hardware and the biological systems were performed. The sequence of different steps in MPU fabrication (cutting, drilling, cleaning, growth surface coating, and sterilization) was optimized in order to reach full biocompatibility. Different coatings of the foil used as growth surface revealed that coating with 0.1 mg/ml poly-D-lysine supports cell attachment better than collagen type I. The tests of prototype hardware (Science Model) proved its full functionality for automated medium change, irradiation and fixation of cells. Exposure of

  1. Space experiment "Cellular Responses to Radiation in Space (CellRad)": Hardware and biological system tests.

    PubMed

    Hellweg, Christine E; Dilruba, Shahana; Adrian, Astrid; Feles, Sebastian; Schmitz, Claudia; Berger, Thomas; Przybyla, Bartos; Briganti, Luca; Franz, Markus; Segerer, Jürgen; Spitta, Luis F; Henschenmacher, Bernd; Konda, Bikash; Diegeler, Sebastian; Baumstark-Khan, Christa; Panitz, Corinna; Reitz, Günther

    2015-11-01

    One factor contributing to the high uncertainty in radiation risk assessment for long-term space missions is the insufficient knowledge about possible interactions of radiation with other spaceflight environmental factors. Such factors, e.g. microgravity, have to be considered as possibly additive or even synergistic factors in cancerogenesis. Regarding the effects of microgravity on signal transduction, it cannot be excluded that microgravity alters the cellular response to cosmic radiation, which comprises a complex network of signaling pathways. The purpose of the experiment "Cellular Responses to Radiation in Space" (CellRad, formerly CERASP) is to study the effects of combined exposure to microgravity, radiation and general space flight conditions on mammalian cells, in particular Human Embryonic Kidney (HEK) cells that are stably transfected with different plasmids allowing monitoring of proliferation and the Nuclear Factor κB (NF-κB) pathway by means of fluorescent proteins. The cells will be seeded on ground in multiwell plate units (MPUs), transported to the ISS, and irradiated by an artificial radiation source after an adaptation period at 0 × g and 1 × g. After different incubation periods, the cells will be fixed by pumping a formaldehyde solution into the MPUs. Ground control samples will be treated in the same way. For implementation of CellRad in the Biolab on the International Space Station (ISS), tests of the hardware and the biological systems were performed. The sequence of different steps in MPU fabrication (cutting, drilling, cleaning, growth surface coating, and sterilization) was optimized in order to reach full biocompatibility. Different coatings of the foil used as growth surface revealed that coating with 0.1 mg/ml poly-D-lysine supports cell attachment better than collagen type I. The tests of prototype hardware (Science Model) proved its full functionality for automated medium change, irradiation and fixation of cells. Exposure of

  2. A Test of the Relationship between Reading Ability & Standardized Biology Assessment Scores

    ERIC Educational Resources Information Center

    Allen, Denise A.

    2014-01-01

    Little empirical evidence suggested that independent reading abilities of students enrolled in biology predicted their performance on the Biology I Graduation End-of-Course Assessment (ECA). An archival study was conducted at one Indiana urban public high school in Indianapolis, Indiana, by examining existing educational assessment data to test…

  3. Using Middle School Test Scores to Predict Success in Ninth Grade Biology

    ERIC Educational Resources Information Center

    McDowell, Lorrie D.

    2013-01-01

    Success in ninth grade is essential to a student's success throughout high school. Many high schools retain the traditional science course sequence of teaching biology first to ninth graders who may or may not be cognitively ready for today's biology content. A few school districts in Georgia are offering a flexible science course sequence in the…

  4. Host-specificity testing on Leipothrix dipsacivagus (Acari: Eriophyidae), a candidate for biological control of Dipsacus spp.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leipothrix dipsacivagus Petanovic & Rector is the first eriophyid mite recorded from hosts in the genus Dipsacus and is considered a potential candidate for biological control of invasive teasels (Dipsacaceae). Host-specificity testing on Leipothrix dipsacivagus (Acari: Eriophyidae) was carried out ...

  5. Inferring local competition intensity from patch size distributions: a test using biological soil crusts

    USGS Publications Warehouse

    Bowker, Matthew A.; Maestre, Fernando T.

    2012-01-01

    Dryland vegetation is inherently patchy. This patchiness goes on to impact ecology, hydrology, and biogeochemistry. Recently, researchers have proposed that dryland vegetation patch sizes follow a power law which is due to local plant facilitation. It is unknown what patch size distribution prevails when competition predominates over facilitation, or if such a pattern could be used to detect competition. We investigated this question in an alternative vegetation type, mosses and lichens of biological soil crusts, which exhibit a smaller scale patch-interpatch configuration. This micro-vegetation is characterized by competition for space. We proposed that multiplicative effects of genetics, environment and competition should result in a log-normal patch size distribution. When testing the prevalence of log-normal versus power law patch size distributions, we found that the log-normal was the better distribution in 53% of cases and a reasonable fit in 83%. In contrast, the power law was better in 39% of cases, and in 8% of instances both distributions fit equally well. We further hypothesized that the log-normal distribution parameters would be predictably influenced by competition strength. There was qualitative agreement between one of the distribution's parameters (μ) and a novel intransitive (lacking a 'best' competitor) competition index, suggesting that as intransitivity increases, patch sizes decrease. The correlation of μ with other competition indicators based on spatial segregation of species (the C-score) depended on aridity. In less arid sites, μ was negatively correlated with the C-score (suggesting smaller patches under stronger competition), while positive correlations (suggesting larger patches under stronger competition) were observed at more arid sites. We propose that this is due to an increasing prevalence of competition transitivity as aridity increases. These findings broaden the emerging theory surrounding dryland patch size distributions

  6. Magnetic response measurements of mesoscopic superconducting and normal metal rings

    NASA Astrophysics Data System (ADS)

    Bluhm, Hendrik

    The main part of this thesis reports three experiments on the magnetic response of mesoscopic superconducting and normal metal rings using a scanning SQUID microscope. The first experiment explores the magnetic response and fluxoid transitions of superconducting, mesoscopic bilayer aluminum rings in the presence of two coupled order parameters arising from the layered structure. For intermediate couplings, metastable states that have different phase winding numbers around the ring in each of the two order parameters were observed. Larger coupling locks the relative phase, so that the two order parameters are only manifest in the temperature dependence of the response. With increasing proximitization, this signature gradually disappears. The data can be described with a two-order-parameter Ginzburg-Landau theory. The second experiment concentrates on fluxoid transitions in similar, but single-layer rings. Near the critical temperature, the transitions, which are induced by applying a flux to the ring, only admit a single fluxoid at a time. At lower temperatures, several fluxoids enter or leave at once, and the final state approaches the ground state. Currently available theoretical frameworks cannot quantitatively explain the data. Heating and quasiparticle diffusion are likely important for a quantitative understanding of this experiment, which could provide a model system for studying the nonlinear dynamics of superconductors far from equilibrium. The third and most important scanning SQUID study concerns 33 individual mesoscopic gold rings. All measured rings show a paramagnetic linear susceptibility and a poorly understood anomaly around zero field, both of which are likely due to unpaired defect spins. The response of sufficiently small rings also has a component that is periodic in the flux through the ring, with a period close to h/e. Its amplitude varies in sign and magnitude from ring to ring, and its typical value and temperature dependence agree with

  7. Science Library of Test Items. Volume Seventeen. A Collection of Multiple Choice Test Items Relating Mainly to Biology.

    ERIC Educational Resources Information Center

    New South Wales Dept. of Education, Sydney (Australia).

    As one in a series of test item collections developed by the Assessment and Evaluation Unit of the Directorate of Studies, items are made available to teachers for the construction of unit tests or term examinations or as a basis for class discussion. Each collection was reviewed for content validity and reliability. The test items meet syllabus…

  8. Optical Mirror from Laser-Trapped Mesoscopic Particles

    NASA Astrophysics Data System (ADS)

    Grzegorczyk, Tomasz M.; Rohner, Johann; Fournier, Jean-Marc

    2014-01-01

    Trapping of mesoscopic particles by optical forces usually relies on the gradient force, whereby particles are attracted into optical wells formed by landscaping the intensity of an optical field. This is most often achieved by optical Gaussian beams, interference patterns, general phase contrast methods, or other mechanisms. Hence, although the simultaneous trapping of several hundreds of particles can be achieved, these particles remain mostly independent with negligible interaction. Optical matter, however, relies on close packing and binding forces, with fundamentally different electrodynamic properties. In this Letter, we build ensembles of optically bound particles to realize a reflective surface that can be used to image an object or to focus a light beam. To our knowledge, this is the first experimental proof of the creation of a mirror by optical matter, and represents an important step toward the realization of a laser-trapped mirror (LTM) in space. From a theoretical point of view, optically bound close packing requires an exact solver of Maxwell's equations in order to precisely compute the field scattered by the collection of particles. Such rigorous calculations have been developed and are used here to study the focusing and resolving power of an LTM.

  9. The circuit architecture of whole brains at the mesoscopic scale.

    PubMed

    Mitra, Partha P

    2014-09-17

    Vertebrate brains of even moderate size are composed of astronomically large numbers of neurons and show a great degree of individual variability at the microscopic scale. This variation is presumably the result of phenotypic plasticity and individual experience. At a larger scale, however, relatively stable species-typical spatial patterns are observed in neuronal architecture, e.g., the spatial distributions of somata and axonal projection patterns, probably the result of a genetically encoded developmental program. The mesoscopic scale of analysis of brain architecture is the transitional point between a microscopic scale where individual variation is prominent and the macroscopic level where a stable, species-typical neural architecture is observed. The empirical existence of this scale, implicit in neuroanatomical atlases, combined with advances in computational resources, makes studying the circuit architecture of entire brains a practical task. A methodology has previously been proposed that employs a shotgun-like grid-based approach to systematically cover entire brain volumes with injections of neuronal tracers. This methodology is being employed to obtain mesoscale circuit maps in mouse and should be applicable to other vertebrate taxa. The resulting large data sets raise issues of data representation, analysis, and interpretation, which must be resolved. Even for data representation the challenges are nontrivial: the conventional approach using regional connectivity matrices fails to capture the collateral branching patterns of projection neurons. Future success of this promising research enterprise depends on the integration of previous neuroanatomical knowledge, partly through the development of suitable computational tools that encapsulate such expertise. PMID:25233311

  10. Energy transfer in mesoscopic vibrational systems enabled by eigenfrequency fluctuations

    NASA Astrophysics Data System (ADS)

    Atalaya, Juan

    Energy transfer between low-frequency vibrational modes can be achieved by means of nonlinear coupling if their eigenfrequencies fulfill certain nonlinear resonance conditions. Because of the discreteness of the vibrational spectrum at low frequencies, such conditions may be difficult to satisfy for most low-frequency modes in typical mesoscopic vibrational systems. Fluctuations of the vibrational eigenfrequencies can also be relatively strong in such systems. We show that energy transfer between modes can occur in the absence of nonlinear resonance if frequency fluctuations are allowed. The case of three modes with cubic nonlinear coupling and no damping is particularly interesting. It is found that the system has a non-thermal equilibrium state which depends only on the initial conditions. The rate at which the system approaches to such state is determined by the parameters such as the noise strength and correlation time, the nonlinearity strength and the detuning from exact nonlinear resonance. We also discuss the case of many weakly coupled modes. Our results shed light on the problem of energy relaxation of low-frequency vibrational modes into the continuum of high-frequency vibrational modes. The results have been obtained with Mark Dykman. Alternative email: jatalaya2012@gmail.com.

  11. Analysing DNA structural parameters using a mesoscopic model

    NASA Astrophysics Data System (ADS)

    Amarante, Tauanne D.; Weber, Gerald

    2014-03-01

    The Peyrard-Bishop model is a mesoscopic approximation to model DNA and RNA molecules. Several variants of this model exists, from 3D Hamiltonians, including torsional angles, to simpler 2D versions. Currently, we are able to parametrize the 2D variants of the model which allows us to extract important information about the molecule. For example, with this technique we were able recently to obtain the hydrogen bonds of RNA from melting temperatures, which previously were obtainable only from NMR measurements. Here, we take the 3D torsional Hamiltonian and set the angles to zero. Curiously, in doing this we do not recover the traditional 2D Hamiltonians. Instead, we obtain a different 2D Hamiltonian which now includes a base pair step distance, commonly known as rise. A detailed knowledge of the rise distance is important as it determines the overall length of the DNA molecule. This 2D Hamiltonian provides us with the exciting prospect of obtaining DNA structural parameters from melting temperatures. Our results of the rise distance at low salt concentration are in good qualitative agreement with those from several published x-ray measurements. We also found an important dependence of the rise distance with salt concentration. In contrast to our previous calculations, the elastic constants now show little dependence with salt concentrations which appears to be closer to what is seen experimentally in DNA flexibility experiments.

  12. Electron-photon coupling in mesoscopic quantum electrodynamics

    NASA Astrophysics Data System (ADS)

    Cottet, A.; Kontos, T.; Douçot, B.

    2015-05-01

    Understanding the interaction between cavity photons and electronic nanocircuits is crucial for the development of mesoscopic quantum electrodynamics (QED). One has to combine ingredients from atomic cavity QED, such as orbital degrees of freedom, with tunneling physics and strong cavity field inhomogeneities, specific to superconducting circuit QED. It is therefore necessary to introduce a formalism which bridges between these two domains. We develop a general method based on a photonic pseudopotential to describe the electric coupling between electrons in a nanocircuit and cavity photons. In this picture, photons can induce simultaneously orbital energy shifts, tunneling, and local orbital transitions. We study in detail the elementary example of a single quantum dot with a single normal metal reservoir, coupled to a cavity. Photon-induced tunneling terms lead to a nonuniversal relation between the cavity frequency pull and the damping pull. Our formalism can also be applied to multiple quantum dot circuits, molecular circuits, quantum point contacts, metallic tunnel junctions, and superconducting nanostructures enclosing Andreev bound states or Majorana bound states, for instance.

  13. Mesoscopic structure formation in condensed matter due to vacuum fluctuations

    NASA Astrophysics Data System (ADS)

    Sen, Siddhartha; Gupta, Kumar S.; Coey, J. M. D.

    2015-10-01

    An observable influence of zero-point fluctuations of the vacuum electromagnetic field on bound electrons is well known in the hydrogen atom, where it produces the Lamb shift. Here, we adapt an approach used to explain the Lamb shift in terms of a slight expansion of the orbits due to interaction with the zero-point field and apply it to assemblies of N electrons that are modeled as independent atomically bound two-level systems. The effect is to stabilize a collective ground-state energy, which leads to a prediction of novel effects at room temperature for quasi-two-dimensional systems over a range of parameters in the model, namely, N , the two-level excitation energy ℏ ω and the ionization energy ℏ ω +ɛ . Some mesoscopic systems where these effects may be observable include water sheaths on protein or DNA, surfaces of gaseous nanobubbles, and the magnetic response of inhomogeneous, electronically dilute oxides. No such effects are envisaged for uniform three-dimensional systems.

  14. Bridging microscopic and mesoscopic simulations of lipid bilayers.

    PubMed Central

    Ayton, Gary; Voth, Gregory A

    2002-01-01

    A lipid bilayer is modeled using a mesoscopic model designed to bridge atomistic bilayer simulations with macro-scale continuum-level simulation. Key material properties obtained from detailed atomistic-level simulations are used to parameterize the meso-scale model. The fundamental length and time scale of the meso-scale simulation are at least an order of magnitude beyond that used at the atomistic level. Dissipative particle dynamics cast in a new membrane formulation provides the simulation methodology. A meso-scale representation of a dimyristoylphosphatidylcholine membrane is examined in the high and low surface tension regimes. At high surface tensions, the calculated modulus is found to be slightly less than the atomistically determined value. This result agrees with the theoretical prediction that high-strain thermal undulations still persist, which have the effect of reducing the value of the atomistically determined modulus. Zero surface tension simulations indicate the presence of strong thermal undulatory modes, whereas the undulation spectrum and the calculated bending modulus are in excellent agreement with theoretical predictions and experiment. PMID:12496103

  15. The Circuit Architecture of Whole Brains at the Mesoscopic Scale

    PubMed Central

    Mitra, Partha P.

    2014-01-01

    Vertebrate brains of even moderate size are composed of astronomically large numbers of neurons and show a great degree of individual variability at the microscopic scale. This variation is presumably the result of phenotypic plasticity and individual experience. At a larger scale, however, relatively stable species-typical spatial patterns are observed in neuronal architecture, e.g., the spatial distributions of somata and axonal projection patterns, probably the result of a genetically encoded developmental program. The mesoscopic scale of analysis of brain architecture is the transitional point between a microscopic scale where individual variation is prominent and the macroscopic level where a stable, species-typical neural architecture is observed. The empirical existence of this scale, implicit in neuroanatomical atlases, combined with advances in computational resources, makes studying the circuit architecture of entire brains a practical task. A methodology has previously been proposed that employs a shotgun-like grid-based approach to systematically cover entire brain volumes with injections of neuronal tracers. This methodology is being employed to obtain mesoscale circuit maps in mouse and should be applicable to other vertebrate taxa. The resulting large data sets raise issues of data representation, analysis, and interpretation, which must be resolved. Even for data representation the challenges are nontrivial: the conventional approach using regional connectivity matrices fails to capture the collateral branching patterns of projection neurons. Future success of this promising research enterprise depends on the integration of previous neuroanatomical knowledge, partly through the development of suitable computational tools that encapsulate such expertise. PMID:25233311

  16. Activated wetting dynamics in the presence of mesoscopic surface disorder

    NASA Astrophysics Data System (ADS)

    Davitt, Kristina; Pettersen, Michael; Rolley, Etienne

    2012-02-01

    Although disorder is commonly used to explain contact angle hysteresis, it is often neglected when considering wetting dynamics. When viscous forces are negligible, contact-line velocity is modelled by the Molecular Kinetic Theory [1], which predicts an activated motion driven by molecular jumps on preferential adsorption sites. We believe that in the presence of mesoscopic disorder, this model can be reinterpreted and that the activation length is no longer molecular-sized but is related to depinning events on the surface. This hypothesis is supported by a study of the wetting of cesium by liquid hydrogen in which it was shown that the activation length is of the order of the expected roughness [2]. However, no systematic study between the activation area and the length scale of the disorder has previously been made. We study wetting dynamics on metal films evaporated under different conditions, allowing us to obtain films with lateral grain sizes ranging from 10 to 200 nm. We find that the activation area deduced from wetting experiments is coherent with these sizes; however, its precise relation to the scale of disorder is not clear.[1] T.D. Blake and J.M. Haynes, J. Colloid Interface Sci. 30, 421 (1969)[2] E. Rolley and C. Guthmann, PRL 98, 166105 (2007)

  17. Mesoscopic Higher Regularity and Subadditivity in Elliptic Homogenization

    NASA Astrophysics Data System (ADS)

    Armstrong, Scott; Kuusi, Tuomo; Mourrat, Jean-Christophe

    2016-05-01

    We introduce a new method for obtaining quantitative results in stochastic homogenization for linear elliptic equations in divergence form. Unlike previous works on the topic, our method does not use concentration inequalities (such as Poincaré or logarithmic Sobolev inequalities in the probability space) and relies instead on a higher (C k , k ≥ 1) regularity theory for solutions of the heterogeneous equation, which is valid on length scales larger than a certain specified mesoscopic scale. This regularity theory, which is of independent interest, allows us to, in effect, localize the dependence of the solutions on the coefficients and thereby accelerate the rate of convergence of the expected energy of the cell problem by a bootstrap argument. The fluctuations of the energy are then tightly controlled using subadditivity. The convergence of the energy gives control of the scaling of the spatial averages of gradients and fluxes (that is, it quantifies the weak convergence of these quantities), which yields, by a new "multiscale" Poincaré inequality, quantitative estimates on the sublinearity of the corrector.

  18. Scanning gate transconductance microscopy and spectroscopy of a mesoscopic ring

    NASA Astrophysics Data System (ADS)

    Hackens, Benoit; Martins, Frederico; Faniel, Sebastien; Bayot, Vincent; Pala, Marco; Sellier, Hermann; Huant, Serge; Desplanque, Ludovic; Wallart, Xavier

    2011-03-01

    In scanning gate microscopy (SGM), a dc voltage is applied to a sharp tip moving in the vicinity of a device. This alters the electrostatic potential seen by electrons inside the device, and consequently changes the device conductance. Here, we superimpose a small ac voltage to the dc bias applied on the tip, and record the change of device conductance at the tip bias modulation frequency, i.e. the local transconductance. We first image the low temperature transconductance of a mesoscopic ring patterned in a two-dimensional electron system (2DES) hosted in an InGaAs/InAlAs heterostructure. The tranconductance images are decorated by concentric features that we associate with charging of electron traps located close to the 2DES. We perform spectroscopy of these traps by positioning the tip close to them, and recording the ring transconductance as a function of the tip dc voltage and the bias accross the quantum ring. We observe Coulomb diamonds in our spectroscopic data, which confirms that Coulomb blockade is at play.

  19. Reconstructing protein remodeled membranes in molecular detail from mesoscopic models

    PubMed Central

    Lyman, Edward; Cui, Haosheng; Voth, Gregory A.

    2014-01-01

    We present a method for “inverse coarse graining,” rebuilding a higher resolution model from a lower resolution one, in order to rebuild protein coats for remodeled membranes of complex topology. The specific case of membrane remodeling by N-BAR domain containing proteins is considered here, although the overall method is general and thus applicable to other membrane remodeling phenomena. Our approach begins with a previously developed, discretized mesoscopic continuum membrane model (EM2) which has been shown to capture the reticulated membrane topologies often observed for N-BAR/liposome systems by electron microscopy (EM). The information in the EM2 model — directions of the local curvatures and a low resolution sample of the membrane surface — is then used to construct a coarse-grained (CG) system with one site per lipid and 26 sites per protein. We demonstrate the approach on pieces of EM2 structures with three different topologies that have been observed by EM: A tubule, a “Y” junction, and a torus. We show that the approach leads to structures that are stable under subsequent constant temperature CG simulation, and end by considering the future application of the methodology as a hybrid approach that combines experimental information with computer modeling. PMID:21503332

  20. Mesoscopic harmonic mapping of electromechanical response in a relaxor ferroelectric

    NASA Astrophysics Data System (ADS)

    Vasudevan, Rama K.; Zhang, Shujun; Ding, Jilai; Okatan, M. Baris; Jesse, Stephen; Kalinin, Sergei V.; Bassiri-Gharb, Nazanin

    2015-06-01

    Relaxor-ferroelectrics are renowned for very large electrostrictive response, enabling applications in transducers, actuators, and energy harvesters. However, insight into the dissimilar contributions (polarization rotation, wall motion) to the electromechanical response from electrostrictive strain, and separation of such contributions from linear piezoelectric response are largely ignored at the mesoscale. Here, we employ a band-excitation piezoresponse force microscopy (BE-PFM) technique to explore the first and second harmonics of the piezoelectric response in prototypical relaxor-ferroelectric 0.72Pb(Mg1/3Nb2/3)O3-0.28PbTiO3 (PMN-0.28PT) single crystals. Third order polynomial fitting of the second harmonic reveals considerable correlation between the cubic coefficient map and the first harmonic piezoresponse amplitude. These results are interpreted under a modified Rayleigh framework, as evidence for domain wall contributions to enhanced electromechanical response. These studies highlight the contribution of domain wall motion in the electromechanical response of relaxor ferroelectrics, and further show the utility of harmonic BE-PFM measurements in spatially mapping the mesoscopic variability inherent in disordered systems.

  1. Computational approach to phenomenological mesoscopic field dislocation mechanics

    NASA Astrophysics Data System (ADS)

    Roy, Anish

    2005-11-01

    A variety of physically observed size-effects and patterning behavior in plastic response at the micron scale and below have raised interesting challenges for the modeling of plastic flow at these scales. In this thesis, two such models appropriate for length scales of < 0.1mum and 0.1mum-100mum are considered. The first (FDM) is conceptually appropriate for scales where all dislocations are resolved. The second (PMFDM) is a moving space-time averaged version of the first, appropriate for mesoscopic plasticity. In the first part of the thesis, FDM is shown to be capable of representing the elastic stress fields of dislocation distributions in a generally anisotropic medium of finite extent. It is also shown to have some success, naturally limited as expected, in prediction of yield drop, back stress and development of inhomogeneity from homogeneous initial conditions and boundary conditions which would otherwise produce homogeneous deformation in conventional plasticity. The space-time averaged version of FDM, PMFDM, requires additional closure statements due to the inherent nonlinearity of FDM. This is achieved through the use of a robust macroscopic model of strain-gradient plasticity that attempts to model effects of geometrically-necessary dislocations only in work-hardening. Finite element method-based computational predictions of the theory demonstrate several experimentally observed features of meso and macro scale plasticity. The model, which fundamentally accounts for fine scale dislocation mechanisms, seems to be an adequate representation of plasticity for these scales.

  2. Mesoscopic structure of neuronal tracts from time-dependent diffusion

    PubMed Central

    Burcaw, Lauren M.; Fieremans, Els; Novikov, Dmitry S.

    2015-01-01

    Interpreting brain diffusion MRI measurements in terms of neuronal structure at a micrometer level is an exciting unresolved problem. Here we consider diffusion transverse to a bundle of fibers, and show theoretically, as well as using Monte Carlo simulations and measurements in a phantom made of parallel fibers mimicking axons, that the time dependent diffusion coefficient approaches its macroscopic limit slowly, in a (lnt)/t fashion. The logarithmic singularity arises due to short range disorder in the fiber packing. We identify short range disorder in axonal fibers based on histological data from the splenium, and argue that the time dependent contribution to the overall diffusion coefficient from the extra-axonal water dominates that of the intra-axonal water. This dominance may explain the bias in measuring axon diameters in clinical settings. The short range disorder is also reflected in the linear frequency dependence of the diffusion coefficient measured with oscillating gradients, in agreement with recent experiments. Our results relate the measured diffusion to the mesoscopic structure of neuronal tissue, uncovering the sensitivity of diffusion metrics to axonal arrangement within a fiber tract, and providing an alternative interpretation of axonal diameter mapping techniques. PMID:25837598

  3. PRATHAM: Parallel Thermal Hydraulics Simulations using Advanced Mesoscopic Methods

    SciTech Connect

    Joshi, Abhijit S; Jain, Prashant K; Mudrich, Jaime A; Popov, Emilian L

    2012-01-01

    At the Oak Ridge National Laboratory, efforts are under way to develop a 3D, parallel LBM code called PRATHAM (PaRAllel Thermal Hydraulic simulations using Advanced Mesoscopic Methods) to demonstrate the accuracy and scalability of LBM for turbulent flow simulations in nuclear applications. The code has been developed using FORTRAN-90, and parallelized using the message passing interface MPI library. Silo library is used to compact and write the data files, and VisIt visualization software is used to post-process the simulation data in parallel. Both the single relaxation time (SRT) and multi relaxation time (MRT) LBM schemes have been implemented in PRATHAM. To capture turbulence without prohibitively increasing the grid resolution requirements, an LES approach [5] is adopted allowing large scale eddies to be numerically resolved while modeling the smaller (subgrid) eddies. In this work, a Smagorinsky model has been used, which modifies the fluid viscosity by an additional eddy viscosity depending on the magnitude of the rate-of-strain tensor. In LBM, this is achieved by locally varying the relaxation time of the fluid.

  4. Escape of a mesoscopic particle from a modulated optical trap

    NASA Astrophysics Data System (ADS)

    Kruse, J. R.; Dykman, M. I.; Golding, B.

    2003-03-01

    We describe experiments on noise-induced escape of a mesoscopic particle from a bistable potential well. The potential is created by the interaction of two focused laser beams with a glass sphere of diameter ˜ 1 μm. The trapping potential is mapped quantitatively in 3-dimensions by a statistical method [1]. The dynamics of the particle can be varied from highly overdamped to underdamped by tuning the density of the surrounding environment. The eigenfrequencies of the trapped particle, as well as over-barrier transition rates W, have been directly measured as a function of damping. When the potential is modulated, the escape probability of the particle over the potential barrier becomes synchronized with the driving field. At large modulation amplitude, we find that the system approaches a saddle-node bifurcation. We have measured the critical exponent that describes the amplitude dependence of ln W as the bifurcation point is approached. By varying the modulation frequency, it is possible to probe the non-adiabatic region where the critical exponent has been predicted to change, with results in agreement with theory and numerical simulations. [1] L.I. McCann, M.I. Dykman, and B. Golding, Nature 402, 785 (1999).

  5. Critical tests for determination of microbiological quality and biological activity in commercial vermicompost samples of different origins.

    PubMed

    Grantina-Ievina, Lelde; Andersone, Una; Berkolde-Pīre, Dace; Nikolajeva, Vizma; Ievinsh, Gederts

    2013-12-01

    The aim of the present paper was to show that differences in biological activity among commercially produced vermicompost samples can be found by using a relatively simple test system consisting of microorganism tests on six microbiological media and soilless seedling growth tests with four vegetable crop species. Significant differences in biological properties among analyzed samples were evident both at the level of microbial load as well as plant growth-affecting activity. These differences were mostly manufacturer- and feedstock-associated, but also resulted from storage conditions of vermicompost samples. A mature vermicompost sample that was produced from sewage sludge still contained considerable number of Escherichia coli. Samples from all producers contained several potentially pathogenic fungal species such as Aspergillus fumigatus, Pseudallescheria boidii, Pseudallescheria fimeti, Pseudallescheria minutispora, Scedosporium apiospermum, Scedosporium prolificans, Scopulariopsis brevicaulis, Stachybotrys chartarum, Geotrichum spp., Aphanoascus terreus, and Doratomyces columnaris. In addition, samples from all producers contained plant growth-promoting fungi from the genera Trichoderma and Mortierella. The described system can be useful both for functional studies aiming at understanding of factors affecting quality characteristics of vermicompost preparations and for routine testing of microbiological quality and biological activity of organic waste-derived composts and vermicomposts. PMID:23504062

  6. Testing biological effects of hand-washing grey water for reuse in irrigation on an urban farm: a case study.

    PubMed

    Khan, Mohammad Zain; Sim, Yei Lin; Lin, Yang Jian; Lai, Ka Man

    2013-01-01

    The feasibility of reusing hand-washing grey water contaminated with antibacterial hand-washing liquid for irrigation purposes in an urban farm is explored in this case study. Experiments are carried out to investigate if the quality of this grey water allows for its reuse in agriculture as per the guidelines established by the World Health Organization (WHO). However, there is no guideline to test the biological effect of grey water prior to agricultural use. It is plausible that the antibacterial property of the grey water can harm the soil microbial system and plants when applied to land, even if all other water quality parameters satisfy the WHO limit. We use algae (Chlorella vulgaris) and indigenous soil bacteria as initial plant and soil bacteria indicators, respectively, to test the potential inhibition of the water on plants and soil bacteria. Results show that the chemical oxygen demand (COD) of the grey water is 10% higher than the WHO permissible level, while all other water quality parameters are within the limits after four days of our experimental period. An inhibitory effect is observed in all of the biological tests. However, the inhibitory effect on algae and soil bacteria is not observed after the four-day period. The case study demonstrates a new approach for testing the biological effect of grey water, which can be used in conjunction with the WHO guideline, and provides data for this urban farm to set up a future water treatment system for grey-water reuse in irrigation. PMID:23530370

  7. Energy utilization in fluctuating biological energy converters

    PubMed Central

    Szőke, Abraham; Hajdu, Janos

    2016-01-01

    We have argued previously [Szoke et al., FEBS Lett. 553, 18–20 (2003); Curr. Chem. Biol. 1, 53–57 (2007)] that energy utilization and evolution are emergent properties based on a small number of established laws of physics and chemistry. The relevant laws constitute a framework for biology on a level intermediate between quantum chemistry and cell biology. There are legitimate questions whether these concepts are valid at the mesoscopic level. Such systems fluctuate appreciably, so it is not clear what their efficiency is. Advances in fluctuation theorems allow the description of such systems on a molecular level. We attempt to clarify this topic and bridge the biochemical and physical descriptions of mesoscopic systems. PMID:27191009

  8. Cosmic radiation exposure of biological test systems during the EXPOSE-R mission

    NASA Astrophysics Data System (ADS)

    Berger, Thomas; Hajek, Michael; Bilski, Pawel

    2015-01-01

    In the frame of the EXPOSE-R mission outside the Russian Zvezda Module of the International Space Station (ISS) passive thermoluminescence dosimeters were applied to measure the radiation exposure of biological samples. The detectors were located beneath the sample carriers to determine the dose levels for maximum shielding. The dose measured beneath the sample carriers varied between 317 +/- 10 and 230 +/- 2 mGy, which amount to an average dose rate of 381 +/- 12 and 276 +/- 2 μGy d-1. These values are close to those assessed for the interior of the ISS and reflect the high shielding of the biological experiments within the EXPOSE-R facility. As a consequence of the high shielding (several g cm-2), the biological samples were predominantly exposed to galactic cosmic heavy ions and trapped protons in the Earth's radiation belts, whereas the trapped electrons did not reach the samples.

  9. The effects of co-teaching on student test performance and attitudes towards science in high school biology

    NASA Astrophysics Data System (ADS)

    Cole, Virginia Scott

    Reform efforts in response to the inclusion of students with disabilities into general education classrooms have become necessary to shift students' placements into the science classroom. An investigation into the effects of co-teaching in high school biology classrooms was conducted to explore the impact of two models of co-teaching on biology students' achievement and their attitudes towards science. Quantitative data were collected using a diagnostic exam, student chapter test scores, and the Scientific Attitude Inventory II (SAI II) (Moore & Foy, 1997). Additionally, qualitative data were collected from student and teacher interviews, as well as reflections recorded by the general education participating teacher. The study occurred at a predominantly African-American high school in an Alabama city school with approximately 700 students. The population for the study was composed of 62 high school biology students, with 18 of those students placed inclusively in the biology classroom as a result of No Child Left Behind legislation. The participating teachers consisted of one general education biology teacher and one highly qualified, science special education teacher. Twelve students, along with the special education participating teacher, were interviewed and provided qualitative data after completion of the study. The general education teacher provided teacher reflection responses to contribute qualitatively on the impact of co-teaching in high school biology. Quantitative data analysis was performed using descriptive statistics, ANOVA, and paired samples t tests analyses. ANOVA results revealed that there were no changes in student test scores of achievement due to the models of instruction implemented. The implementation of no co-teaching, station teaching, and the one-teaching, one-drifting co-teaching models of instruction did not result in significant changes in students' achievement. Furthermore, paired samples t tests revealed no change in students

  10. A Discriminant Analytic Test of Biglan's Theoretical Distinction between Biology and English Department Chairpersons.

    ERIC Educational Resources Information Center

    Hayward, Patricia C.

    1986-01-01

    Discriminant functional analysis was used to compare structural variables of department size, institution type, and highest degree awarded with academic discipline to determine which accounts for more variance in biology and English department chairpersons' responses to questions concerning their influence. Generally, structural variables…

  11. Testing Effect and Complex Comprehension in a Large Introductory Undergraduate Biology Course

    ERIC Educational Resources Information Center

    Pagliarulo, Christopher L.

    2011-01-01

    Traditional undergraduate biology courses are content intensive, requiring students to understand and remember large amounts of information in short periods of time. Yet most students maintain little of the material encountered during their education. Poor knowledge retention is a main cause of academic failure and high undergraduate attrition…

  12. 77 FR 30887 - Amendments to Sterility Test Requirements for Biological Products; Correction

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-24

    ... rule that appeared in the Federal Register of May 3, 2012. (77 FR 26162). The final rule provides... Biologics Evaluation and Research (HFM-17), Food and Drug Administration, 1401 Rockville Pike, Suite 200N, Rockville, MD 20852- 1448, 301-827-6210. SUPPLEMENTARY INFORMATION: In FR Doc. 2012-10649, appearing on...

  13. Selection of test plant list for weed biological control with molecular and biochemical data

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The initial steps of weed biological control programs involve the determination of the host range of a prospective agent prior to consideration for release. Accurately predicting the host range of a potential agent is fundamental to this process. This may be conducted first in the country of origin ...

  14. Membrane materials for storing biological samples intended for comparative nanotoxicological testing

    NASA Astrophysics Data System (ADS)

    Metelkin, A.; Kuznetsov, D.; Kolesnikov, E.; Chuprunov, K.; Kondakov, S.; Osipov, A.; Samsonova, J.

    2015-11-01

    The study is aimed at identifying the samples of most promising membrane materials for storing dry specimens of biological fluids (Dried Blood Spots, DBS technology). Existing sampling systems using cellulose fiber filter paper have a number of drawbacks such as uneven distribution of the sample spot, dependence of the spot spreading area on the individual biosample properties, incomplete washing-off of the sample due to partially inconvertible sorption of blood components on cellulose fibers, etc. Samples of membrane materials based on cellulose, polymers and glass fiber with applied biosamples were studied using methods of scanning electron microscopy, FT-IR spectroscopy and surface-wetting measurement. It was discovered that cellulose-based membrane materials sorb components of biological fluids inside their structure, while membranes based on glass fiber display almost no interaction with the samples and biological fluid components dry to films in the membrane pores between the structural fibers. This characteristic, together with the fact that membrane materials based on glass fiber possess sufficient strength, high wetting properties and good storage capacity, attests them as promising material for dry samples of biological fluids storage systems.

  15. VALIDITY OF EFFLUENT AND AMBIENT TOXICITY TESTS FOR PREDICTING BIOLOGICAL IMPACT, SCIPPO CREEK, CIRCLEVILLE, OHIO

    EPA Science Inventory

    The report describes the first site study on Scippo Creek at Circleville, Ohio, which receives only one discharge from a chemical resins plant using batch operations. Scippo Creek is a small sunfish/bass stream flowing through an agricultural area in central Ohio. Previous biolog...

  16. Transport dissipative particle dynamics model for mesoscopic advection-diffusion-reaction problems.

    PubMed

    Li, Zhen; Yazdani, Alireza; Tartakovsky, Alexandre; Karniadakis, George Em

    2015-07-01

    We present a transport dissipative particle dynamics (tDPD) model for simulating mesoscopic problems involving advection-diffusion-reaction (ADR) processes, along with a methodology for implementation of the correct Dirichlet and Neumann boundary conditions in tDPD simulations. tDPD is an extension of the classic dissipative particle dynamics (DPD) framework with extra variables for describing the evolution of concentration fields. The transport of concentration is modeled by a Fickian flux and a random flux between tDPD particles, and the advection is implicitly considered by the movements of these Lagrangian particles. An analytical formula is proposed to relate the tDPD parameters to the effective diffusion coefficient. To validate the present tDPD model and the boundary conditions, we perform three tDPD simulations of one-dimensional diffusion with different boundary conditions, and the results show excellent agreement with the theoretical solutions. We also performed two-dimensional simulations of ADR systems and the tDPD simulations agree well with the results obtained by the spectral element method. Finally, we present an application of the tDPD model to the dynamic process of blood coagulation involving 25 reacting species in order to demonstrate the potential of tDPD in simulating biological dynamics at the mesoscale. We find that the tDPD solution of this comprehensive 25-species coagulation model is only twice as computationally expensive as the conventional DPD simulation of the hydrodynamics only, which is a significant advantage over available continuum solvers. PMID:26156459

  17. Transport dissipative particle dynamics model for mesoscopic advection-diffusion-reaction problems

    NASA Astrophysics Data System (ADS)

    Li, Zhen; Yazdani, Alireza; Tartakovsky, Alexandre; Karniadakis, George Em

    2015-07-01

    We present a transport dissipative particle dynamics (tDPD) model for simulating mesoscopic problems involving advection-diffusion-reaction (ADR) processes, along with a methodology for implementation of the correct Dirichlet and Neumann boundary conditions in tDPD simulations. tDPD is an extension of the classic dissipative particle dynamics (DPD) framework with extra variables for describing the evolution of concentration fields. The transport of concentration is modeled by a Fickian flux and a random flux between tDPD particles, and the advection is implicitly considered by the movements of these Lagrangian particles. An analytical formula is proposed to relate the tDPD parameters to the effective diffusion coefficient. To validate the present tDPD model and the boundary conditions, we perform three tDPD simulations of one-dimensional diffusion with different boundary conditions, and the results show excellent agreement with the theoretical solutions. We also performed two-dimensional simulations of ADR systems and the tDPD simulations agree well with the results obtained by the spectral element method. Finally, we present an application of the tDPD model to the dynamic process of blood coagulation involving 25 reacting species in order to demonstrate the potential of tDPD in simulating biological dynamics at the mesoscale. We find that the tDPD solution of this comprehensive 25-species coagulation model is only twice as computationally expensive as the conventional DPD simulation of the hydrodynamics only, which is a significant advantage over available continuum solvers.

  18. Transport dissipative particle dynamics model for mesoscopic advection-diffusion-reaction problems

    PubMed Central

    Yazdani, Alireza; Tartakovsky, Alexandre; Karniadakis, George Em

    2015-01-01

    We present a transport dissipative particle dynamics (tDPD) model for simulating mesoscopic problems involving advection-diffusion-reaction (ADR) processes, along with a methodology for implementation of the correct Dirichlet and Neumann boundary conditions in tDPD simulations. tDPD is an extension of the classic dissipative particle dynamics (DPD) framework with extra variables for describing the evolution of concentration fields. The transport of concentration is modeled by a Fickian flux and a random flux between tDPD particles, and the advection is implicitly considered by the movements of these Lagrangian particles. An analytical formula is proposed to relate the tDPD parameters to the effective diffusion coefficient. To validate the present tDPD model and the boundary conditions, we perform three tDPD simulations of one-dimensional diffusion with different boundary conditions, and the results show excellent agreement with the theoretical solutions. We also performed two-dimensional simulations of ADR systems and the tDPD simulations agree well with the results obtained by the spectral element method. Finally, we present an application of the tDPD model to the dynamic process of blood coagulation involving 25 reacting species in order to demonstrate the potential of tDPD in simulating biological dynamics at the mesoscale. We find that the tDPD solution of this comprehensive 25-species coagulation model is only twice as computationally expensive as the conventional DPD simulation of the hydrodynamics only, which is a significant advantage over available continuum solvers. PMID:26156459

  19. Cosmic Radiation Exposure of Biological Test Systems During the EXPOSE-E Mission

    PubMed Central

    Hajek, Michael; Bilski, Pawel; Körner, Christine; Vanhavere, Filip; Reitz, Günther

    2012-01-01

    Abstract In the frame of the EXPOSE-E mission on the Columbus external payload facility EuTEF on board the International Space Station, passive thermoluminescence dosimeters were applied to measure the radiation exposure of biological samples. The detectors were located either as stacks next to biological specimens to determine the depth dose distribution or beneath the sample carriers to determine the dose levels for maximum shielding. The maximum mission dose measured in the upper layer of the depth dose part of the experiment amounted to 238±10 mGy, which relates to an average dose rate of 408±16 μGy/d. In these stacks of about 8 mm height, the dose decreased by 5–12% with depth. The maximum dose measured beneath the sample carriers was 215±16 mGy, which amounts to an average dose rate of 368±27 μGy/d. These values are close to those assessed for the interior of the Columbus module and demonstrate the high shielding of the biological experiments within the EXPOSE-E facility. Besides the shielding by the EXPOSE-E hardware itself, additional shielding was experienced by the external structures adjacent to EXPOSE-E, such as EuTEF and Columbus. This led to a dose gradient over the entire exposure area, from 215±16 mGy for the lowest to 121±6 mGy for maximum shielding. Hence, the doses perceived by the biological samples inside EXPOSE-E varied by 70% (from lowest to highest dose). As a consequence of the high shielding, the biological samples were predominantly exposed to galactic cosmic heavy ions, while electrons and a significant fraction of protons of the radiation belts and solar wind did not reach the samples. Key Words: Space radiation—Dosimetry—Passive radiation detectors—Thermoluminescence—EXPOSE-E. Astrobiology 12, 387–392. PMID:22680685

  20. Cosmic radiation exposure of biological test systems during the EXPOSE-E mission.

    PubMed

    Berger, Thomas; Hajek, Michael; Bilski, Pawel; Körner, Christine; Vanhavere, Filip; Reitz, Günther

    2012-05-01

    In the frame of the EXPOSE-E mission on the Columbus external payload facility EuTEF on board the International Space Station, passive thermoluminescence dosimeters were applied to measure the radiation exposure of biological samples. The detectors were located either as stacks next to biological specimens to determine the depth dose distribution or beneath the sample carriers to determine the dose levels for maximum shielding. The maximum mission dose measured in the upper layer of the depth dose part of the experiment amounted to 238±10 mGy, which relates to an average dose rate of 408±16 μGy/d. In these stacks of about 8 mm height, the dose decreased by 5-12% with depth. The maximum dose measured beneath the sample carriers was 215±16 mGy, which amounts to an average dose rate of 368±27 μGy/d. These values are close to those assessed for the interior of the Columbus module and demonstrate the high shielding of the biological experiments within the EXPOSE-E facility. Besides the shielding by the EXPOSE-E hardware itself, additional shielding was experienced by the external structures adjacent to EXPOSE-E, such as EuTEF and Columbus. This led to a dose gradient over the entire exposure area, from 215±16 mGy for the lowest to 121±6 mGy for maximum shielding. Hence, the doses perceived by the biological samples inside EXPOSE-E varied by 70% (from lowest to highest dose). As a consequence of the high shielding, the biological samples were predominantly exposed to galactic cosmic heavy ions, while electrons and a significant fraction of protons of the radiation belts and solar wind did not reach the samples. PMID:22680685

  1. A versatile system for biological and soil chemical tests on a planetary landing craft. I - Scientific objectives

    NASA Technical Reports Server (NTRS)

    Radmer, R. J.; Kok, B.; Martin, J. P.

    1976-01-01

    We describe an approach for the remote detection and characterization of life in planetary soil samples. A mass spectrometer is used as the central sensor to monitor changes in the gas phase in eleven test cells filled with soil. Many biological assays, ranging from general 'in situ' assays to specific metabolic processes (such as photosynthesis, respiration, denitrification, etc.) can be performed by appropriate additions to the test cell via attached preloaded injector capsules. The system is also compatible with a number of chemical assays such as the analysis of atmospheric composition (both chemical and isotopic), the status of soil water, and the determination of compounds of carbon, nitrogen and sulfur in the soil.

  2. Mesoscopics of ultrasound and seismic waves: application to passive imaging

    NASA Astrophysics Data System (ADS)

    Larose, É.

    2006-05-01

    This manuscript deals with different aspects of the propagation of acoustic and seismic waves in heterogeneous media, both simply and multiply scattering ones. After a short introduction on conventional imaging techniques, we describe two observations that demonstrate the presence of multiple scattering in seismic records: the equipartition principle, and the coherent backscattering effect (Chap. 2). Multiple scattering is related to the mesoscopic nature of seismic and acoustic waves, and is a strong limitation for conventional techniques like medical or seismic imaging. In the following part of the manuscript (Chaps. 3 5), we present an application of mesoscopic physics to acoustic and seismic waves: the principle of passive imaging. By correlating records of ambient noise or diffuse waves obtained at two passive sensors, it is possible to reconstruct the impulse response of the medium as if a source was placed at one sensor. This provides the opportunity of doing acoustics and seismology without a source. Several aspects of this technique are presented here, starting with theoretical considerations and numerical simulations (Chaps. 3, 4). Then we present experimental applications (Chap. 5) to ultrasound (passive tomography of a layered medium) and to seismic waves (passive imaging of California, and the Moon, with micro-seismic noise). Physique mésoscopique des ultrasons et des ondes sismiques : application à l'imagerie passive. Cet article de revue rassemble plusieurs aspects fondamentaux et appliqués de la propagation des ondes acoustiques et élastiques dans les milieux hétérogènes, en régime de diffusion simple ou multiple. Après une introduction sur les techniques conventionelles d'imagerie sismique et ultrasonore, nous présentons deux expériences qui mettent en évidence la présence de diffusion multiple dans les enregistrements sismologiques : l'équipartition des ondes, et la rétrodiffusion cohérente (Chap. 2). La diffusion multiple des

  3. Transport studies of mesoscopic and magnetic topological insulators

    NASA Astrophysics Data System (ADS)

    Kandala, Abhinav

    Topological Insulators (TI) are a novel class of materials that are ideally insulating in the bulk, but have gapless, metallic states at the surface. These surface states have very exciting properties such as suppressed backscattering and spin-momentum locking, which are of great interest for research efforts towards dissipation-less electronics and spintronics. The popular thermo-electrics from the Bi chalcogenide family -- Bi2Se3 and Bi 2Te3 -- have been experimentally demonstrated to be promising candidate TI materials, and form the chosen material system for this dissertation research. The first part of this dissertation research focuses on low temperature magneto-transport measurements of mesoscopic topological insulator devices (Chapter 3). The top-down patterning of epitaxial thin films of Bi2Se 3 and Bi2Te3 (that are plagued with bulk conduction) is motivated, in part, by an effort to enhance the surface-to-volume ratio in mesoscopic channels. At cryogenic temperatures, transport measurements of these devices reveal periodic conductance fluctuations in straight channel devices, despite the lack of any explicit patterning of the TI film into a ring or a loop. A careful analysis of the surface morphology and comparison with the transport data then demonstrate that scattering off the edges of triangular plateaus at the surface leads to the creation of Aharonov-Bohm electronic orbits responsible for the periodicity. Another major focus of this dissertation work is on combining topological insulators with magnetism. This has been shown to open a gap in the surface states leading to possibilities of magnetic "gating" and the realization of dissipation-less transport at zero-field, amongst several other exotic quantum phenomena. In this dissertation, I present two different schemes for probing these effects in electrical transport devices -- interfacing with insulating ferromagnets (Chapter 4) and bulk magnetic doping (Chapter 5). In Chapter 4, I shall present the

  4. [The importance of using biological test objects in studying the toxicity of surface-active substances].

    PubMed

    Mudryĭ, I V; Debrivnaia, I E

    1996-01-01

    The Azotobacter agilis [correction of azobacter agile] culture appeared to be the most sensitive one among the studied test objects. Buckwheat as a test plant can be recommended in studying the toxicity of surface-active substances. PMID:9035856

  5. Magnetic responses in 1D mesoscopic rings and cylinders

    NASA Astrophysics Data System (ADS)

    Maiti, Santanu K.

    2006-03-01

    I investigated a detailed study of persistent current and low-field magnetic susceptibility in one-dimensional mesoscopic rings and cylinders threaded by slowly varying magnetic flux φ in the tight-binding model. In perfect rings described by constant number of electrons Ne, current shows only saw-tooth variation with φ, while for those rings described by constant chemical potential μ, current varies saw-tooth like for some special choices of μ, but in all other cases it shows kink-like structures. On the other hand, in perfect cylinders I get both saw-tooth and kink-like structures in persistent current whether these cylinders are described by constant Ne or μ. In presence of impurity, current gets a continuous variation with φ only for the rings described by constant Ne, while in all other cases it depends on the choice of μ. My exact calculation predicts that the diamagnetic and paramagnetic sign of the low-field currents can be determined exactly for the rings described by constant Ne. In perfect rings, I get only diamagnetic currents both for odd and even Ne, while in presence of impurity current always shows diamagnetic sign for the rings with odd Ne and paramagnetic sign for the rings with even Ne. Both for the perfect and disordered rings described by constant μ the sign of the current cannot be mentioned exactly since it depends on the choice of μ and disordered configurations. Similar arguments are also true for the cylinders those are described either by constant Ne or by constant μ since the sign of the current in these systems depends on Ne, μ and disordered configurations.

  6. Mesoscopic dynamics of diffusion-influenced enzyme kinetics.

    PubMed

    Chen, Jiang-Xing; Kapral, Raymond

    2011-01-28

    A particle-based mesoscopic model for enzyme kinetics is constructed and used to investigate the influence of diffusion on the reactive dynamics. Enzymes and enzyme-substrate complexes are modeled as finite-size soft spherical particles, while substrate, product, and solvent molecules are point particles. The system is evolved using a hybrid molecular dynamics-multiparticle collision dynamics scheme. Both the nonreactive and reactive dynamics are constructed to satisfy mass, momentum, and energy conservation laws, and reversible reaction steps satisfy detailed balance. Hydrodynamic interactions among the enzymes and complexes are automatically accounted for in the dynamics. Diffusion manifests itself in various ways, notably in power-law behavior in the evolution of the species concentrations. In accord with earlier investigations, regimes where the product production rate exhibits either monotonic or nonmonotonic behavior as a function of time are found. In addition, the species concentrations display both t(-1/2) and t(-3/2) power-law behavior, depending on the dynamical regime under investigation. For high enzyme volume fractions, cooperative effects influence the enzyme kinetics. The time dependent rate coefficient determined from the mass action rate law is computed and shown to depend on the enzyme concentration. Lifetime distributions of substrate molecules newly released in complex dissociation events are determined and shown to have either a power-law form for rebinding to the same enzyme from which they were released or an exponential form for rebinding to different enzymes. The model can be used and extended to explore a variety of issues related concentration effects and diffusion on enzyme kinetics. PMID:21280744

  7. Concentration fluctuations in a mesoscopic oscillating chemical reaction system

    NASA Astrophysics Data System (ADS)

    Qian, Hong; Saffarian, Saveez; Elson, Elliot L.

    2002-08-01

    Under sustained pumping, kinetics of macroscopic nonlinear biochemical reaction systems far from equilibrium either can be in a stationary steady state or can execute sustained oscillations about a fixed mean. For a system of two dynamic species X and Y, the concentrations nx and ny will be constant or will repetitively trace a closed loop in the (nx, ny) phase plane, respectively. We study a mesoscopic system with nx and ny very small; hence the occurrence of random fluctuations modifies the deterministic behavior and the law of mass action is replaced by a stochastic model. We show that nx and ny execute cyclic random walks in the (nx, ny) plane whether or not the deterministic kinetics for the corresponding macroscopic system represents a steady or an oscillating state. Probability distributions and correlation functions for nx(t) and ny(t) show quantitative but not qualitative differences between states that would appear as either oscillating or steady in the corresponding macroscopic systems. A diffusion-like equation for probability P(nx, ny, t) is obtained for the two-dimensional Brownian motion in the (nx, ny) phase plane. In the limit of large nx, ny, the deterministic nonlinear kinetics derived from mass action is recovered. The nature of large fluctuations in an oscillating nonequilibrium system and the conceptual difference between "thermal stochasticity" and "temporal complexity" are clarified by this analysis. This result is relevant to fluorescence correlation spectroscopy and metabolic reaction networks. fluorescence correlation spectroscopy | limit cycle | nanobiochemistry | nonequilibrium steady state | random walk

  8. Mesoscopic coarse-grained simulations of lysozyme adsorption.

    PubMed

    Yu, Gaobo; Liu, Jie; Zhou, Jian

    2014-05-01

    Coarse-grained simulations are adopted to study the adsorption behavior of lysozyme on different (hydrophobic, neutral hydrophilic, zwitterionic, negatively charged, and positively charged) surfaces at the mesoscopic microsecond time scale (1.2 μs). Simulation results indicate the following: (i) the conformation change of lysozyme on the hydrophobic surface is bigger than any other studied surfaces; (ii) the active sites of lysozyme are faced to the hydrophobic surface with a "top end-on" orientation, while they are exposed to the liquid phase on the hydrophilic surface with a "back-on" orientation; (iii) the neutral hydrophilic surface can induce the adsorption of lysozyme, while the nonspecific protein adsorption can be resisted by the zwitterionic surface; (iv) when the solution ionic strength is low, lysozyme can anchor on the negatively charged surface easily but cannot adsorb on the positively charged surface; (v) when the solution ionic strength is high, the positively charged lysozyme can also adsorb on the like-charged surface; (vi) the major positive potential center of lysozyme, especially the residue ARG128, plays a vital role in leading the adsorption of lysozyme on charged surfaces; (vii) when the ionic strength is high, a counterion layer is formed above the positively charged surface, which is the key factor why lysozyme can adsorb on a like-charged surface. The coarse-grained method based on the MARTINI force field for proteins and the BMW water model could provide an efficient way to understand protein interfacial adsorption behavior at a greater length scale and time scale. PMID:24785197

  9. Self-consistent theory for systems with mesoscopic fluctuations.

    PubMed

    Ciach, A; Góźdź, W T

    2016-10-19

    We have developed a theory for inhomogeneous systems that allows for the incorporation of the effects of mesoscopic fluctuations. A hierarchy of equations relating the correlation and direct correlation functions for the local excess [Formula: see text] of the volume fraction of particles ζ has been obtained, and an approximation leading to a closed set of equations for the two-point functions has been introduced for the disordered inhomogeneous phase. We have numerically solved the self-consistent equations for one-dimensional (1D) and three-dimensional (3D) models with short-range attraction and long-range repulsion. Predictions for all of the qualitative properties of the 1D model agree with the exact results, but only semi-quantitative agreement is obtained in the simplest version of the theory. The effects of fluctuations in the two 3D models considered are significantly different, despite the very similar properties of these models in the mean-field approximation. In both cases we obtain the sequence of large-small-large compressibility for increasing ζ. The very small compressibility is accompanied by the oscillatory decay of correlations with correlation lengths that are orders of magnitude larger than the size of particles. In one of the two models considered, the small compressibility becomes very small and the large compressibility becomes very large with decreasing temperature, and eventually van der Waals loops appear. Further studies are necessary in order to determine the nature of the strongly inhomogeneous phase present for intermediate volume fractions in 3D. PMID:27545343

  10. Tunable quasiparticle trapping in Meissner and vortex states of mesoscopic superconductors

    NASA Astrophysics Data System (ADS)

    Taupin, M.; Khaymovich, I. M.; Meschke, M.; Mel'Nikov, A. S.; Pekola, J. P.

    2016-03-01

    Nowadays, superconductors serve in numerous applications, from high-field magnets to ultrasensitive detectors of radiation. Mesoscopic superconducting devices, referring to those with nanoscale dimensions, are in a special position as they are easily driven out of equilibrium under typical operating conditions. The out-of-equilibrium superconductors are characterized by non-equilibrium quasiparticles. These extra excitations can compromise the performance of mesoscopic devices by introducing, for example, leakage currents or decreased coherence time in quantum devices. By applying an external magnetic field, one can conveniently suppress or redistribute the population of excess quasiparticles. In this article, we present an experimental demonstration and a theoretical analysis of such effective control of quasiparticles, resulting in electron cooling both in the Meissner and vortex states of a mesoscopic superconductor. We introduce a theoretical model of quasiparticle dynamics, which is in quantitative agreement with the experimental data.

  11. Giant Mesoscopic Fluctuations and Long-Range Superconducting Correlations in Superconductor-Ferromagnet Structures.

    PubMed

    Mel'nikov, A S; Buzdin, A I

    2016-08-12

    The fluctuating superconducting correlations emerging in dirty hybrid structures under the conditions of the strong proximity effect are demonstrated to affect the validity range of the widely used formalism of Usadel equations at mesoscopic scales. In superconductor-ferromagnet structures these giant mesoscopic fluctuations originating from the interference effects for the Cooper pair wave function in the presence of the exchange field can be responsible for an anomalously slow decay of superconducting correlations in a ferromagnet even when the noncollinear and spin-orbit effects are negligible. The resulting sample-to-sample fluctuations of the Josephson current in superconductor-ferromagnetic-superconductor junctions and the local density of states in superconductor-ferromagnetic hybrid structures can provide an explanation of the long-range proximity phenomena observed in mesoscopic samples with collinear magnetization. PMID:27563990

  12. Tunable quasiparticle trapping in Meissner and vortex states of mesoscopic superconductors

    PubMed Central

    Taupin, M.; Khaymovich, I. M.; Meschke, M.; Mel'nikov, A. S.; Pekola, J. P.

    2016-01-01

    Nowadays, superconductors serve in numerous applications, from high-field magnets to ultrasensitive detectors of radiation. Mesoscopic superconducting devices, referring to those with nanoscale dimensions, are in a special position as they are easily driven out of equilibrium under typical operating conditions. The out-of-equilibrium superconductors are characterized by non-equilibrium quasiparticles. These extra excitations can compromise the performance of mesoscopic devices by introducing, for example, leakage currents or decreased coherence time in quantum devices. By applying an external magnetic field, one can conveniently suppress or redistribute the population of excess quasiparticles. In this article, we present an experimental demonstration and a theoretical analysis of such effective control of quasiparticles, resulting in electron cooling both in the Meissner and vortex states of a mesoscopic superconductor. We introduce a theoretical model of quasiparticle dynamics, which is in quantitative agreement with the experimental data. PMID:26980225

  13. Tunable quasiparticle trapping in Meissner and vortex states of mesoscopic superconductors.

    PubMed

    Taupin, M; Khaymovich, I M; Meschke, M; Mel'nikov, A S; Pekola, J P

    2016-01-01

    Nowadays, superconductors serve in numerous applications, from high-field magnets to ultrasensitive detectors of radiation. Mesoscopic superconducting devices, referring to those with nanoscale dimensions, are in a special position as they are easily driven out of equilibrium under typical operating conditions. The out-of-equilibrium superconductors are characterized by non-equilibrium quasiparticles. These extra excitations can compromise the performance of mesoscopic devices by introducing, for example, leakage currents or decreased coherence time in quantum devices. By applying an external magnetic field, one can conveniently suppress or redistribute the population of excess quasiparticles. In this article, we present an experimental demonstration and a theoretical analysis of such effective control of quasiparticles, resulting in electron cooling both in the Meissner and vortex states of a mesoscopic superconductor. We introduce a theoretical model of quasiparticle dynamics, which is in quantitative agreement with the experimental data. PMID:26980225

  14. Giant Mesoscopic Fluctuations and Long-Range Superconducting Correlations in Superconductor-Ferromagnet Structures

    NASA Astrophysics Data System (ADS)

    Mel'nikov, A. S.; Buzdin, A. I.

    2016-08-01

    The fluctuating superconducting correlations emerging in dirty hybrid structures under the conditions of the strong proximity effect are demonstrated to affect the validity range of the widely used formalism of Usadel equations at mesoscopic scales. In superconductor-ferromagnet structures these giant mesoscopic fluctuations originating from the interference effects for the Cooper pair wave function in the presence of the exchange field can be responsible for an anomalously slow decay of superconducting correlations in a ferromagnet even when the noncollinear and spin-orbit effects are negligible. The resulting sample-to-sample fluctuations of the Josephson current in superconductor-ferromagnetic-superconductor junctions and the local density of states in superconductor-ferromagnetic hybrid structures can provide an explanation of the long-range proximity phenomena observed in mesoscopic samples with collinear magnetization.

  15. A second generation mesoscopic lipid bilayer model: Connections to field-theory descriptions of membranes and nonlocal hydrodynamics

    NASA Astrophysics Data System (ADS)

    Ayton, Gary S.; McWhirter, J. Liam; Voth, Gregory A.

    2006-02-01

    A new mesoscopic membrane model is developed in order to examine long-wavelength structural and dynamical membrane phenomena. Two different explicit mesoscopic solvent models are employed. The first mesoscopic solvent is denoted the big liquid oscillating blob system, which is parametrized to model water at a coarse-grained level and is motivated by a Langevin-like approach; the resulting membrane dynamics predict a solvent viscosity dependence consistent with the known viscosity of water. The second mesoscopic solvent is a Weeks-Chandler-Anderson model. Here, it is found that the correct mesoscopic hydrodynamic scaling of the membrane undulation dynamics is still preserved, although accelerated. When the behavior of the two membranes in close proximity to one another is examined, very little correlated motion is observed. However, the theoretically predicted scaling of the entropic undulation energy is confirmed, demonstrating that the entropic interaction between two membranes becomes increasingly repulsive with decreasing separation.

  16. Testing biological liquid samples using modified m-line spectroscopy method

    NASA Astrophysics Data System (ADS)

    Augusciuk, Elzbieta; Rybiński, Grzegorz

    2005-09-01

    Non-chemical method of detection of sugar concentration in biological (animal and plant source) liquids has been investigated. Simplified set was build to show the easy way of carrying out the survey and to make easy to gather multiple measurements for error detecting and statistics. Method is suggested as easy and cheap alternative for chemical methods of measuring sugar concentration, but needing a lot effort to be made precise.

  17. Instrument for controlling the application of mechanical loads to biological and bicompatible test subjects

    DOEpatents

    Lintilhac, P.M.; Vesecky, T.B.

    1995-09-19

    An apparatus and methods are disclosed facilitating the application of forces and measurement of dimensions of a test subject. In one arrangement the test subject is coupled to a forcing frame and controlled forces applied thereto. Force applied to the test subject is measured and controlled. A dimensional characteristic of the test subject, such as growth, is measured by a linear variable differential transformer. The growth measurement data can be used to control the force applied. The transducer module receives force and dimensional data from the forcing frame. The transducer module is a separate, microprocessor-based unit that communicates the test data to a controller unit that controls the application of force to the test subject and receives the test data from the transducer module for force control, storage, and/or communication to the user. 8 figs.

  18. Instrument for controlling the application of mechanical loads to biological and bicompatible test subjects

    DOEpatents

    Lintilhac, Phillip M.; Vesecky, Thompson B.

    1995-01-01

    Apparatus and methods are disclosed facilitating the application of forces and measurement of dimensions of a test subject. In one arrangement the test subject is coupled to a forcing frame and controlled forces applied thereto. Force applied to the test subject is measured and controlled. A dimensional characteristic of the test subject, such as growth, is measured by a linear variable differential transformer. The growth measurement data can be used to control the force applied. The transducer module receives force and dimensional data from the forcing frame. The transducer module is a separate, microprocessor-based unit that communicates the test data to a controller unit that controls the application of force to the test subject and receives the test data from the transducer module for force control, storage, and/or communication to the user.

  19. 1 alpha,25-dihydroxyvitamin D3 analogs featuring aromatic and heteroaromatic rings: design, synthesis, and preliminary biological testing.

    PubMed

    Posner, G H; Li, Z; White, M C; Vinader, V; Takeuchi, K; Guggino, S E; Dolan, P; Kensler, T W

    1995-10-27

    Aromatic compounds 2a-c, analogs of 1 alpha, 25-dihydroxyvitamin (calcitriol, 1), and heteroaromatic compounds 4a-c and 5a-c, analogs of 19-nor-1 alpha, 25-dihydroxyvitamin D3 (3), were designed to simulate the topology of their biologically potent parent compounds while avoiding previtamin D equilibrium. Convergent and facile total syntheses of the analogs (+)-2b, (+)-2c, (-)-4b, and (-)-5b were achieved via carbonyl addition of regiospecifically formed organolithium nucleophiles to the enantiomerically pure C,D-ring ketone (+)-17, characteristic of natural calcitriol (1). Likewise, hybrid analogs 20a-c were prepared to determine whether incorporation of a known potentiating side chain would lead to increased biological activity. Preliminary in vitro biological testing showed that aromatic analogs (+)-2b, (+)-2c, and 20a-c as well as heteroaromatic analogs (-)-4b and (-)-5b have very low affinities for the calf thymus vitamin D receptor but considerable antiproliferative activities in murine keratinocytes at micromolar concentration. No biological advantage was observed in this keratinocyte assay for the doubly modified hybrid analogs 20a-c over the singly modified parent (+)-2b. Analog (+)-2b, but surprisingly not the corresponding analog 20b differing from (+)-2b only in the side chain, showed considerable activity in nongenomic opening of calcium channels in rat osteosarcoma cells. PMID:7473581

  20. Probabilistic simulation of mesoscopic “Schrödinger cat” states

    NASA Astrophysics Data System (ADS)

    Opanchuk, B.; Rosales-Zárate, L.; Reid, M. D.; Drummond, P. D.

    2014-02-01

    We carry out probabilistic phase-space sampling of mesoscopic Schrödinger cat quantum states, demonstrating multipartite Bell violations for up to 60 qubits. We use states similar to those generated in photonic and ion-trap experiments. These results show that mesoscopic quantum superpositions are directly accessible to probabilistic sampling, and we analyze the properties of sampling errors. We also demonstrate dynamical simulation of super-decoherence in ion traps. Our computer simulations can be either exponentially faster or slower than experiment, depending on the correlations measured.

  1. Contact resistance and phase slips in mesoscopic superfluid-atom transport

    NASA Astrophysics Data System (ADS)

    Eckel, S.; Lee, Jeffrey G.; Jendrzejewski, F.; Lobb, C. J.; Campbell, G. K.; Hill, W. T.

    2016-06-01

    We experimentally measure transport of superfluid, bosonic atoms in a mesoscopic system: a small channel connecting two large reservoirs. Starting far from equilibrium (superfluid in a single reservoir), we observe first resistive flow transitioning at a critical current into superflow, characterized by oscillations. We reproduce this full evolution with a simple electronic circuit model. We compare our fitted conductance to two different microscopic phenomenological models. We also show that the oscillations are consistent with LC oscillations as estimated by the kinetic inductance and effective capacitance in our system. Our experiment provides an attractive platform to begin to probe the mesoscopic transport properties of a dilute, superfluid, Bose gas.

  2. Decoherence as attenuation of mesoscopic echoes in a spin-chain channel

    NASA Astrophysics Data System (ADS)

    Álvarez, Gonzalo A.; Danieli, Ernesto P.; Levstein, Patricia R.; Pastawski, Horacio M.

    2010-07-01

    An initial local excitation in a confined quantum system evolves, exploring the whole system and returning to the initial position as a mesoscopic echo at the Heisenberg time. We consider two weakly coupled spin chains, a spin ladder, where one is a quantum channel while the other represents an environment. We quantify decoherence in the quantum channel through the attenuation of the mesoscopic echoes. We evaluate decoherence rates for different ratios between sources of amplitude fluctuation and dephasing in the interchain interaction Hamiltonian. The many-body dynamics is seen as a one-body evolution with a decoherence rate given by the Fermi golden rule.

  3. Biological alternatives to chemical identification for the ecotoxicological assessment of industrial effluents: The RTG-2 in vitro cytotoxicity test

    SciTech Connect

    Castano, A. . Centro de Sanidad Ambiental); Vega, M.; Blazquez, T.; Tarazona, J.V. )

    1994-10-01

    Ecotoxicology is concerned with the effects of chemicals on biological systems. Identifying components of complex aqueous effluents poses special problems, and can be useless if there is a lack of information on the biological effects of the identified chemicals. Toxicity-based (bioassay-directed) sample fractionation can be very useful, but the small amount of fractioned material is a constraint that can be solved by using in vitro tests. The RTG-2 in vitro cytotoxicity test has been used to assess (a) the efficacy of a treatment plant in the aeronautics industry and (b) the exposure of fish and molluscs cultured in Esteiro Bay to the effluent of a fish-processing factory. Ecotoxicological assessments could be done without identifying the responsible chemicals. The RTG-2 test was used in combination with concentration/fractionation procedures. It proved that the toxicity of the liquid wastes from the aeronautics industry was eliminated by the treatment, and that molluscs and fish reared in Esteiro Bay had accumulated toxic chemicals dumped by the fish-processing factory. A combination of the RTG-2 cytotoxicity test and HPLC proved to give useful information even for chemicals not identified by GC-MS.

  4. Biological testing of sediment for the Olympia Harbor Navigation Improvement Project, 1988: Geoduck, amphipod, and echinoderm bioassays

    SciTech Connect

    Ward, J.A.; Word, J.Q.; Antrim, L.D.

    1989-05-01

    The Olympia Harbor Navigation Improvement Project requires the dredging of approximately 330,000 cubic yards (cy) of sediment from the harbor entrance channel and 205,185 cy from the turning basin. Puget Sound Dredged Disposal Analysis (PSDDA) partial characterization studies were used to plan a full sediment characterization in which chemical analyses and biological testing of sediments evaluated the suitability of the dredged material for unconfined, open-water disposal. The US Army Corps of Engineers (COE), Seattle District, contracted with NOAA/NMFS, Environmental Conservation Division, to perform the chemical analysis and Microtox bioassay tests, and with the Battelle/Marine Sciences Laboratory (MSL) in Sequim to perform flow-through solid-phase bioassays utilizing juvenile (8 to 10 mm) geoduck clams, Panopea generosa, and static solid phase bioassays using the phoxocephalid amphipod, Rhepoxynius abronius, developing embryos and gametes of the purple sea urchin, Strongylocentrotus purpuratus, and the larvae of the Pacific oyster Crassostrea gigas. When the results of the biological tests were evaluated under PSDDA guidelines, it was found that all the tested sediment treatments from Olympia Harbor are suitable for unconfined open-water disposal. 14 refs., 12 figs., 3 tabs.

  5. Planar biaxial testing of soft biological tissue using rakes: A critical analysis of protocol and fitting process.

    PubMed

    Fehervary, Heleen; Smoljkić, Marija; Vander Sloten, Jos; Famaey, Nele

    2016-08-01

    Mechanical characterization of soft biological tissue is becoming more and more prevalent. Despite the growing use of planar biaxial testing for soft tissue characterization, testing conditions and subsequent data analysis have not been standardized and vary widely. This also influences the quality of the result of the parameter fitting. Moreover, the testing conditions and data analysis are often not or incompletely reported, which impedes the proper comparison of parameters obtained from different studies. With a focus on planar biaxial tests using rakes, this paper investigates varying testing conditions and varying data analysis methods and their effect on the quality of the parameter fitting results. By means of a series of finite element simulations, aspects such as number of rakes, rakes׳ width, loading protocol, constitutive model, material stiffness and anisotropy are evaluated based on the degree of homogeneity of the stress field, and on the correlation between the experimentally obtained stress and the stress derived from the constitutive model. When calculating the aforementioned stresses, different definitions of the section width and deformation gradient are used in literature, each of which are looked into. Apart from this degree of homogeneity and correlation, also the effect on the quality of the parameter fitting result is evaluated. The results show that inhomogeneities can be reduced to a minimum for wise choices of testing conditions and analysis methods, but never completely eliminated. Therefore, a new parameter optimization procedure is proposed that corrects for the inhomogeneities in the stress field and induces significant improvements to the fitting results. Recommendations are made for best practice in rake-based planar biaxial testing of soft biological tissues and subsequent parameter fitting, and guidelines are formulated for reporting thereof in publications. PMID:26854936

  6. Putting the Biological Species Concept to the Test: Using Mating Networks to Delimit Species

    PubMed Central

    Lagache, Lélia; Leger, Jean-Benoist; Daudin, Jean-Jacques; Petit, Rémy J.; Vacher, Corinne

    2013-01-01

    Although interfertility is the key criterion upon which Mayr’s biological species concept is based, it has never been applied directly to delimit species under natural conditions. Our study fills this gap. We used the interfertility criterion to delimit two closely related oak species in a forest stand by analyzing the network of natural mating events between individuals. The results reveal two groups of interfertile individuals connected by only few mating events. These two groups were largely congruent with those determined using other criteria (morphological similarity, genotypic similarity and individual relatedness). Our study, therefore, shows that the analysis of mating networks is an effective method to delimit species based on the interfertility criterion, provided that adequate network data can be assembled. Our study also shows that although species boundaries are highly congruent across methods of species delimitation, they are not exactly the same. Most of the differences stem from assignment of individuals to an intermediate category. The discrepancies between methods may reflect a biological reality. Indeed, the interfertility criterion is an environment-dependant criterion as species abundances typically affect rates of hybridization under natural conditions. Thus, the methods of species delimitation based on the interfertility criterion are expected to give results slightly different from those based on environment-independent criteria (such as the genotypic similarity criteria). However, whatever the criterion chosen, the challenge we face when delimiting species is to summarize continuous but non-uniform variations in biological diversity. The grade of membership model that we use in this study appears as an appropriate tool. PMID:23818990

  7. Radiotoxicity of gadolinium-148 and radium-223 in mouse testes: relative biological effectiveness of alpha-particle emitters in vivo.

    PubMed

    Howell, R W; Goddu, S M; Narra, V R; Fisher, D R; Schenter, R E; Rao, D V

    1997-03-01

    The biological effects of radionuclides that emit alpha particles are of considerable interest in view of their potential for therapy and their presence in the environment. The present work is a continuation of our ongoing effort to study the radiotoxicity of alpha-particle emitters in vivo using the survival of murine testicular sperm heads as the biological end point. Specifically, the relative biological effectiveness (RBE) of very low-energy alpha particles (3.2 MeV) emitted by 148Gd is investigated and determined to be 7.4 +/- 2.4 when compared to the effects of acute external 120 kVp X rays. This datum, in conjunction with our earlier results for 210Po and 212Pb in equilibrium with its daughters, is used to revise and extend the range of validity of our previous RBE-energy relationship for alpha particles emitted by tissue-incorporated radionuclides. The new empirical relationship is given by RBE alpha = 9.14 - 0.510 E alpha where 3 < E alpha < 9 MeV. The validity of this empirical relationship is tested by determining the RBE of the prolific alpha-particle emitter 223Ra (in equilibrium with its daughters) experimentally in the same biological model and comparing the value obtained experimentally with the predicted value. The resulting RBE values are 5.4 +/- 0.9 and 5.6, respectively. This close agreement strongly supports the adequacy of the empirical RBE-E alpha relationship to predict the biological effects of alpha-particle emitters in vivo. PMID:9052681

  8. Experimental Work in Biology: Book 1, Food Tests; Book 2, Enzymes; Book 3, Soil.

    ERIC Educational Resources Information Center

    Mackean, D. G.

    Laboratory experiments are presented in these first three manuals of a six-volume series for use at the 12- to 16-year-old, or British CSE, level. On the subject of food tests, 17 exercises are prepared in connection with Biuret reactions, starch and emulsion tests, Millon's and Benedict's reagents, reagent sensitivity, and calorific values and…

  9. Alignment between High School Biology Curriculum Standard and the Standardised Tests of Four Provinces in China

    ERIC Educational Resources Information Center

    Lu, Qun; Liu, Enshan

    2012-01-01

    With the development and implementation of new curriculum standards, the field tests of education reform in senior high schools began in 2004 in four pilot provinces in mainland China. After five years of the reform, it is necessary to know how and to what extent the curriculum standard guides test classroom instruction. The present study was…

  10. Proposed biological testing methods for the United States incineration-at-sea research program

    SciTech Connect

    Strobel, C.J.; Gentile, J.H.; Schimmel, S.C.; Carr, R.S.; Williams, J.W.

    1988-01-01

    As part of the United States Environmental Protection Agency's Incineration-at-Sea research program, a suite of toxicity tests has been selected for assessing the toxicity of incinerator emissions generated during the combustion of chlorinated wastes. The test organisms for the five short-term chronic tests are the inland silverside, Menidia beryllina, the myside Mysidopsis bahia, the red macroalga Champia parvula, the polychaete Dinophilus gyrociliatus, and gametes from the sea urchin Arbacia punctulata. The durations of individual tests range from 2 hours to 7 days. The endpoints include survival, growth and reproductive effects. The results have demonstrated that the proposed methodologies can be used to test the toxicity of gaseous emissions, and that there appears to be no significant toxicity associated with the combustion products of a carrier fuel oil.

  11. A biology-based dynamic approach for the reconciliation of acute and chronic toxicity tests: application to Daphnia magna.

    PubMed

    Zaldívar, José-Manuel; Baraibar, Joaquín

    2011-03-01

    There is the need to integrate existing toxicity data in a coherent framework for extending their domain of applicability as well as their extrapolation potential. This integration would also reduce time and cost-consuming aspects of these tests and reduce animal usage. In this work, based on data extracted from literature, we have assessed the advantages that a dynamic biology-toxicant fate coupled model for Daphnia magna could provide when assessing toxicity data, in particular, the possibility to obtain from short-term (acute) toxicity test long-term (chronic) toxicity values taking into account the inherent variability of D. magna populations and the multiple sources of data. The results show that this approach overcomes some of the limitations of existing toxicity tests and that the prediction errors are considerably reduced when compared with the factor from 2 to 5 obtained using acute-to-chronic ratios. PMID:21168184

  12. Mesoscopic Strains Maps in Woven Composite Laminas During Off-axis Tension

    NASA Astrophysics Data System (ADS)

    Anzelotti, G.; Nicoletto, G.; Riva, E.

    2010-06-01

    The mechanics of woven carbon-fiber reinforced plastic (CFRP) composites is influenced by the complex architecture of the reinforcement phase. Computational (i.e. finite element based) approaches have been used increasingly to model not only the global laminate stiffness, but also damage evolution and laminate strength. The modeling combines the identification of the architectural unit cell (UC), the selection of suitable constitutive models of the different phases, the creation of a fine discretization of the UC in finite elements, the application of an incremental solution procedure that solves iteratively for the stresses and strains in the UC, [1]. The experimental validation of computational models is carried out mainly at the macroscopical level, i.e. simulation of the macroscopic stress-strain curve. Damage, however, is a localized, straindependent phenomenon and therefore only accurate strain distribution within the UC (at the mesolevel) can identify critical conditions in terms of damage location, extension and evolution. The validation of computational damage procedures is a key task and full-field optical strain analysis methods appear the ideal instrument. However, only limited examples of direct finte element method (FEM) vs experimental strain correlation are found because of the limited sensitivity and spatial resolution of some techniques and the complexity and applicative difficulty of others. The aim of the present paper is to present the application of the digital image correlation (DIC) technique, [2], to the full-field strain analysis at the mesoscopic level (i.e. within the UC) of a woven CFRP lamina when the direction of loading forms an angle to the material direction. The material under consideration is a woven carbon fiber reinforced epoxy composite. Orthogonal yarns, each made of of several thousand fibers, are woven according the twill-weave architecture is shown in Fig. 1a. Single-ply laminas were manufactured and tested to eliminate

  13. Single and multiple streamer DBD micro-discharges for testing inactivation of biologically contaminated surfaces

    NASA Astrophysics Data System (ADS)

    Prukner, Vaclav; Dolezalova, Eva; Simek, Milan

    2014-10-01

    Highly reactive environment produced by atmospheric-pressure, non-equilibrium plasmas generated by surface dielectric barrier discharges (SDBDs) may be used for inactivation of biologically contaminated surfaces. We investigated decontamination efficiency of reactive environment produced by single/multiple surface streamer micro-discharge driven by amplitude-modulated AC power in coplanar electrode geometry on biologically contaminated surface by Escherichia coli. The discharges were fed by synthetic air with water vapor admixtures at atmospheric pressure, time of treatment was set from 10 second to 10 minutes, diameters of used SDBD electrodes (single and multiple streamer) and homogeneously contaminated disc samples were equal (25 mm), the distance between the electrode and contaminated surface was 2 mm. Both a conventional cultivation and fluorescent method LIVE/DEAD Bacterial Viability kit were applied to estimate counts of bacteria after the plasma treatment. Inactivation was effective and bacteria partly lost ability to grow and became injured and viable/active but non-cultivable (VBNC/ABNC). Work was supported by the MEYS under Project LD13010, VES13 COST CZ (COST Action MP 1101).

  14. Dynamic studies of proton diffusion in mesoscopic heterogeneous matrix

    PubMed Central

    Gutman, M.; Nachliel, E.; Kiryati, S.

    1992-01-01

    The thin water layer, as found in chloroplast or mitochondria, is confined between low dielectric amphypathic surfaces a few nm apart. The physical properties of this mesoscopic space, and how its dimensions affect the rate of chemical reactions proceeding in it, is the subject for this study. The method selected for this purpose is time resolved fluorometry which can monitor the reversible dissociation of a proton from excited molecule of pyranine (8 hydroxy pyrene 1,3,6 tri sulfonate) trapped in thin water layers of a multilamellar vesicle made of neutral or slightly charged phospholipids. The results were analyzed by a computer program of N. Agmon (Pines, E., D. Huppert, and N. Agmon. 1988. J. Am. Chem. Soc. 88:5620-5630) that simulates the diffusion of a proton, subjected to electrostatic attraction, in a thin water layer enclosed between low affinity, proton binding surfaces. The analysis determines the diffusion coefficient of the proton, the effective dielectric constant of the water and the water accessibility of the phosphomoieties of the lipids. These parameters were measured for various lipids [egg-phosphatidylcholine (egg PC), dipalmitoyl phosphatidylcholine (DPPC), cholesterol + DPPC (1:1) and egg PC plus phosphatidyl serine (9:1)] and under varying osmotic pressure which reduces the width of the water layer down to ∼10 ∼ across. We found that: (a) The effective dielectric constant of the aqueous layer, depending on the lipid composition, is ∼40. (b) The diffusion coefficient of the proton in the thin layer (30-10 ∼ across) is that measured in bulk water D = 9.3 10-5 cm2/s, indicating that the water retains its normal liquid state even on contact with the membrane. (c) The reactivity of the phosphomoiety, quantitated by rate of its reaction with proton, diminishes under lateral pressure which reduces the surface area per lipid. We find no evidence for abnormal dynamics of proton transfer at the lipid water interface which, by any mechanism

  15. Quantum transport and dynamics of phonons in mesoscopic systems

    NASA Astrophysics Data System (ADS)

    Santamore, Deborah Hannah

    Recent advances in nanotechnology have shrunk the size of rnesoscopic structures. This allows us to investigate the quantum mechanics of mechanical oscillators. In this thesis we focus on two aspects. In Part I, an individual discrete mode structure of an oscillator and its effect to thermal conductance have been thoroughly examined: Specifically, we investigated the reduction in the thermal conductance in the quantum limit due to phonon scattering by surface roughness, first using scalar waves, then using full three dimensional elasticity theory for an elastic beam with a rectangular cross section. At low frequencies, we find power laws for the scattering coefficients that are strongly mode dependent, and different from the results deriving from Rayleigh scattering of scalar waves, that is often assumed. The scattering gives temperature dependent contributions to the reduction in thermal conductance with the same power laws. At higher frequencies, the scattering coefficient becomes large at the onset frequency of each mode due to the flat dispersion. We use our results to attempt a quantitative understanding of the suppression of the thermal conductance from the universal value observed in experiment. As individual phonon energy becomes comparable to or greater than the thermal energy, the individual phonon dynamics within each mode can be resolved. In Part II, we examine a possibility of detecting individual quanta of a system: We investigate a scheme that makes a quantum non-demolition measurement of the excitation level of a mesoscopic mechanical oscillator by utilizing the anharmonic coupling between two bending modes of an elastic beam. The non-linear coupling between the two modes shifts the resonant frequency of the readout oscillator proportionate to the excitation of the system oscillator. This frequency shift may be detected as a phase shift of the readout oscillation when driven on resonance. We show that in an appropriate regime this measurement

  16. Dispersed oil toxicity tests with biological species indigenous to the Gulf of Mexico. Final report

    SciTech Connect

    Fucik, K.W.; Carr, K.A.; Balcom, B.J.

    1994-08-01

    Static and flowthrough aquatic acute toxicity testing protocols were utilized on eggs and larvae of seven commercially important invertebrates and fishes from the Gulf of Mexico. Test organisms were exposed to Central and Western Gulf oils, dispersed oil, and Corexit 9527. Species included brown shrimp (Penaeus aztecus), white shrimp (Penaeus setiferus), blue crab (Callinectes sapidus), eastern oyster (Crassostrea virginica), red drum (Sciaenops ocellatus), inland silverside (Menidia berylina), and spot (Leiosomus xanthurus). Atlantic menhaden (Brevoortia tyrannus) was also tested because gulf menhaden were not available. Mysids (Mysidopsis bahia) were evaluated as part of a chronic toxicity assessment.

  17. Preparation and antibacterial performance testing of Ag nanoparticles embedded biological materials

    NASA Astrophysics Data System (ADS)

    Li, Xiaoyun; Gao, Guanhui; Sun, Chengjun; Zhu, Yaoyao; Qu, Lingyun; Jiang, Fenghua; Ding, Haibing

    2015-03-01

    In this study, we developed an environmentally friendly chemistry strategy to synthesize Ag nanoparticles (Ag-NPs) embedded biological material, powdered mussel shell (PMS). With the PMS as scaffolds and surfactant, Ag nanoparticles of controllable size dispersed uniformly on it via liquid chemical reduction approach. Morphologies and characteristics of synthesized Ag-NPs/PMS hybrids were analyzed with TEM, SEM and XPS. Antibacterial properties were investigated with Gram-positive bacteria (Arthrobacter sulfureus (A. sulfureus) YACS14, Staphylococcus aureus (S. aureus)) and Gram-negative bacteria (Vibrio anguillarum (V. anguillarum) MVM425, Escherichia coli (E. coli)). The antimicrobial results illustrated that Ag-NPs/PMS composites have antibacterial effect on both sea water and fresh water bacteria with a better effect on sea water bacteria. The degree of antibacterial effect is directly related to the amount of Ag released from Ag-NPs/PMS.

  18. Integrity testing of Planova™ BioEX virus removal filters used in the manufacture of biological products.

    PubMed

    Sekine, Shinya; Komuro, Masayasu; Sohka, Takayuki; Sato, Terry

    2015-05-01

    Confirmation of virus filter integrity is crucial for ensuring the safety of biological products. Two main types of virus filter defects may produce inconsistent and undesirable performance in virus removal: improper pore-size distribution across the membrane; and specific damage, such as tears, broken fibers, or pinholes. Two integrity tests are performed on each individual filter manufactured by Asahi Kasei Medical to ensure the absence of these defects prior to shipment. In this study, we verified that typical usage of Planova™ BioEX filters would not improperly shift the pore-size distribution. Damage occurring during shipment and use (e.g., broken fibers or pinholes) can be detected by end-users with sufficient sensitivity using air-water diffusion based leakage tests. We prepared and tested filters with model pinhole defects of various sizes to develop standard acceptance criteria for the leakage test relative to porcine parvovirus infectivity logarithmic reduction values (LRVs). Our results demonstrate that pinhole defects at or below a certain size for each effective filter surface area have no significant impact on the virus LRV. In conclusion the leakage test is sufficiently sensitive to serve as the sole end-user integrity test for Planova™ BioEX filters, facilitating their use in biopharmaceuticals manufacturing. PMID:25753822

  19. Ecological evaluation of proposed dredged material from the John F. Baldwin Ship Channel: Phase 3 -- biological testing

    SciTech Connect

    Kohn, N.P.; Karle, L.M.; Pinza, M.R.; Mayhew, H.L.; White, P.J.; Gruendell, B.D.; Word, J.Q.

    1993-10-01

    The John F. Baldwin Ship Channel is a 28-mile-long portion of the San Francisco Bay to Stockton Ship Channel, the primary shipping lane through San Francisco Bay and Delta. The San Francisco District of the US Army Corps of Engineers (USACE) is responsible for construction of the John F. Baldwin Ship Channel, which is authorized to be deepened to a project depth of {minus}45 ft relative to mean lower low water (MLLW). Approximately 8.5 million cubic yards (mcy) of sediment will be removed from the channel to reach this project depth. The USACE requested Battelle/Marine Sciences Laboratory (MSL) to conduct testing for ocean disposal under the guidelines in Evaluation of Dredged Material Proposed for Ocean Disposal-Testing Manual (EPA/USACE 1991). This testing manual contains a tiered evaluation approach developed specifically for ocean disposal of dredged material at a selected site. In this study, John F. Baldwin Ship Channel sediments were evaluated under the Tier III (biological) testing guidance, which is considered to be highly stringent and protective of the environment. The Tier III guidance for ocean disposal testing requires tests of water column effects, (following dredged material disposal), deposited sediment toxicity, and bioaccumulation of contaminants from deposited sediment (dredged material).

  20. Reflective mesoscopic spectroscopy for noninvasive detection of reflective index alternations at nano-scale

    NASA Astrophysics Data System (ADS)

    Tao, Yuanhao; Ding, Zhihua

    2011-01-01

    Cancer has been one of the most serious threats to human life. However, there is no substantial improvement in overall treatment of cancer patients. One of the key reasons is the unavailability of convenient method to detect cellular alterations in ultra-early stage of carcinogenesis processes, where genetic aberrations at nano-scale have not yet resulted in histological changes. In this paper, we described an optical method based on reflective mesoscopic spectroscopy for ultra-early cancer detection. According to mesoscopic light transport theory, photons propagating in one dimension (1D) within a weakly disordered medium have the non-self-averaging effect. Reflected signal after 1D propagating is sensitive to any length scale of refractive index fluctuations due to multiple interferences of light waves travelling along 1D trajectory. The principle of mesoscopic spectroscopy for perceiving reflective index fluctuations at length scale of nanometers is introduced. A system for the measurement of reflective mesoscopic spectroscopy based on spatial-incoherence broadband source and spectrometer is established. Simulations on light propagation in cell-emulating model with controlled refractive index distribution are done by finite-difference time-domain (FDTD) approach.

  1. Solubilization of poorly soluble lichen metabolites for biological testing on cell lines.

    PubMed

    Kristmundsdóttir, Thórdís; Jónsdóttir, Elsa; Ogmundsdóttir, Helga M; Ingólfsdóttir, Kristín

    2005-04-01

    The depside atranorin and depsidone fumarprotocetraric acid, isolated from the lichens Stereocaulon alpinum and Cetraria islandica, respectively, were chosen as prototypes for poorly soluble natural compounds in an effort to facilitate testing in pharmacological models. Solubilizing agents previously identified as being non-toxic towards a malignant leukemic (K-562) cell line and suitable for testing of anti-proliferative activity of the dibenzofuran lichen metabolite (+)-usnic acid were used in solubilization studies of the depside and depsidone. Cyclodextrin derivatives were found to be most suitable for solubilizing the lichen compounds, the greatest rise in solubility being witnessed for fumarprotocetraric acid, increasing almost 300-fold from 0.03 mg/ml in water to 8.98 mg/ml in 10% 2-hydroxypropyl-beta-cyclodextrin (HPbetaCD). Subsequently, the lichen compounds, including (+)-usnic acid, were solubilized in 10% HPbetaCD and tested for effects on three malignant human cell lines; T-47D (breast), Panc-1 (pancreas) and PC-3 (prostate) in a standard proliferation assay. Atranorin and fumarprotocetraric acid did not exhibit anti-proliferative effects but usnic acid was active against all test cell lines with EC50 values of 4.3-8.2 microg/ml. The non-toxic solubilizing agents used in this study could prove useful for pharmacological testing of other poorly soluble natural products. PMID:15784343

  2. Determining Biology Student Teachers' Cognitive Structure on the Concept of "Diffusion" through the Free Word-Association Test and the Drawing-Writing Technique

    ERIC Educational Resources Information Center

    Kurt, Hakan; Ekici, Gülay; Aktas, Murat; Aksu, Özlem

    2013-01-01

    The aim of the current study is to investigate student biology teachers' cognitive structures related to "diffusion" through the free word-association test and the drawing-writing technique. As the research design of the study, the qualitative research method was applied. The data were collected from 44 student biology teachers. The free…

  3. Development and testing of new biologically-based polymers as advanced biocompatible contact lenses

    SciTech Connect

    Bertozzi, Carolyn R.

    2000-06-01

    Nature has evolved complex and elegant materials well suited to fulfill a myriad of functions. Lubricants, structural scaffolds and protective sheaths can all be found in nature, and these provide a rich source of inspiration for the rational design of materials for biomedical applications. Many biological materials are based in some fashion on hydrogels, the crosslinked polymers that absorb and hold water. Biological hydrogels contribute to processes as diverse as mineral nucleation during bone growth and protection and hydration of the cell surface. The carbohydrate layer that coats all living cells, often referred to as the glycocalyx, has hydrogel-like properties that keep cell surfaces well hydrated, segregated from neighboring cells, and resistant to non-specific protein deposition. With the molecular details of cell surface carbohydrates now in hand, adaptation of these structural motifs to synthetic materials is an appealing strategy for improving biocompatibility. The goal of this collaborative project between Prof. Bertozzi's research group, the Center for Advanced Materials at Lawrence Berkeley National Laboratory and Sunsoft Corporation was the design, synthesis and characterization of novel hydrogel polymers for improved soft contact lens materials. Our efforts were motivated by the urgent need for improved materials that allow extended wear, and essential feature for those whose occupation requires the use of contact lenses rather than traditional spectacles. Our strategy was to transplant the chemical features of cell surface molecules into contact lens materials so that they more closely resemble the tissue in which they reside. Specifically, we integrated carbohydrate molecules similar to those found on cell surfaces, and sulfoxide materials inspired by the properties of the carbohydrates, into hydrogels composed of biocompatible and manufacturable substrates. The new materials were characterized with respect to surface and bulk hydrophilicity, and

  4. Some biological aspects of Mysidopsis juniae (Crustacea:Mysidacea) and its use in chronic toxicity tests

    SciTech Connect

    Badaro-Pedroso, C. Nipper, M.G.

    1995-12-31

    As part of the joint effort to develop marine toxicity tests with organisms abundant at the Brazilian coast, some aspects for the laboratory culture of M. juniae and its sensitivity to single chemicals were studied. Organisms fed a mixture of brine shrimp (Artemia sp.) nauplii and the microalgae Isochrysis galbana reached sexual maturity 10 days before animals fed brine shrimp nauplii only. Under best conditions, sexual maturity was reached on the 9th--11th day and newborn mysids hatched on the 16th--18th day, Short-term chronic toxicity tests were initiated with 7-day old mysids and exposure time was 11 days, with growth (length and dry weight) as test endpoints. Experiments were undertaken with zinc, copper, and ammonia. Zinc did not affect the organisms at concentrations between 0.018 and 0.1 mg/L, which were one order of magnitude lower than the average 96-h; LC50 value. The NOEC and LOEC values were the same for length and weight in some tests with copper and ammonia (Cu: 0.006 and 0.015 mg/L; NH{sub 3}: 0.32 and 0.87 mg/L, respectively), but revealed length as a more sensitive endpoint than weight in others (length NOEC and LOEC: 0.23 and 0.53 mgNH{sub 3}/L; weight: 0.53 and 0.99 mgNH{sub 3}/L, respectively). The authors speculate that this could be caused by time-dependent variations in the lipid content of the organisms. Length would be a steadier and more reliable endpoint for chronic toxicity tests with M. juniae. The results show that the method has potential applications for the evaluation and monitoring of contaminated marine systems along the Brazilian coast.

  5. From the microscopic to the mesoscopic properties of lyotropic reverse hexagonal liquid crystals.

    PubMed

    Libster, Dima; Ishai, Paul Ben; Aserin, Abraham; Shoham, Gil; Garti, Nissim

    2008-03-01

    In the present study we aimed to explore a correlation between the microstructural properties of the lyotropic reverse hexagonal phase (HII) of the GMO/tricaprylin/phosphatidylcholine/water system and its mesoscopic structure. The mesoscopic organization of discontinuous and anisotropic domains was examined, in the native state, using environmental scanning electron microscopy. The topography of the HII mesophases was imaged directly in their hydrated state, as a function of aqueous-phase concentration and composition, when a proline amino acid was solubilized into the systems as a kosmotropic (water-structure maker) guest molecule. The domain structures of several dozen micrometers in size, visualized in the environmental scanning electron microscopy, were found to possess fractal characteristics, indicating a discontinuous and disordered alignment of the corresponding internal water rods on the mesoscale. On the microstructural level, SAXS measurements revealed that as water content (Cw) increases the characteristic lattice parameter of the mesophases increases as well. Using the water concentration as the mass measure of the mixtures, a scaling relationship between the lattice parameter and the concentration was found to obey a power law whereby the derived fractal dimension was the relevant exponent, confirming the causal link between the microscopic and mesoscopic organizations. The topography of the HII mesophase was found to be affected by the microstructural parameters and the composition of the samples. Thermal analysis experiments involving these systems further confirmed that the behavior of water underpins both microscopical and mesoscopic features of the systems. It was shown that both the swelling of the lattice parameter and the mesoscopic domains is correlated to the bulk water concentration in the water rods. PMID:18197712

  6. The Acid Test for Biological Science: STAP Cells, Trust, and Replication.

    PubMed

    Lancaster, Cheryl

    2016-02-01

    In January 2014, a letter and original research article were published in Nature describing a process whereby somatic mouse cells could be converted into stem cells by subjecting them to stress. These "stimulus-triggered acquisition of pluripotency" (STAP) cells were shown to be capable of contributing to all cell types of a developing embryo, and extra-embryonic tissues. The lead author of the publications, Haruko Obokata, became an overnight celebrity in Japan, where she was dubbed the new face of Japanese science. However, in the weeks that followed publication of the research, issues arose. Other laboratories and researchers (including authors on the original papers) found that they were unable to replicate Obokata et al.'s work. Closer scrutiny of the papers by the scientific community also suggested that there was manipulation of images that had been published, and Obokata was accused of misconduct. Those who should have been supervising her work (also her co-authors on the publications) were also heavily criticised. The STAP cell saga of 2014 is used as an example to highlight the importance of trust and replication in twenty-first century biological science. The role of trust in the scientific community is highlighted, and the effects on interactions between science and the public examined. Similarly, this essay aims to highlight the importance of replication, and how this is understood by researchers, the media, and the public. The expected behaviour of scientists in the twenty-first century is now more closely scrutinised. PMID:25649070

  7. Hydrodynamic Testing of a Biological Sharkskin Replica Manufactured Using the Vacuum Casting Method

    NASA Astrophysics Data System (ADS)

    Luo, Yuehao; Liu, Yufei; Zhang, De Yuan

    2015-02-01

    Numerous facts have validated that sharkskin possesses the obvious drag reduction effect in certain turbulent flowing stations, and it has huge potential and important applications in the fields of agriculture, aerospace, industry, transportation, daily life and so on, which have attracted increased attention throughout the world. To meet the increasing requirements of practical applications, it has been progressively developing into an urgent problem to manufacture sharkskin surfaces with perfect forming quality and high drag-reducing effect. In this paper, the vacuum casting method is put forward to fabricate the drag-reducing surface with the real sharkskin morphology by eliminating the air bubbles from the bottom of sophisticated morphology in the pouring process. Meanwhile, a novel and facile “marking key point” method is explored and adopted to search for the corresponding biological sharkskin and negative template, a more convincing way to evaluate the replicating precision is systematically illustrated and the hydrodynamic experiment is carried out in the water tunnel. The results indicate that wall resistance over sharkskin surface replicated by the vacuum casting method can be decreased by about 12.5% compared with the smooth skin. In addition, the drag reduction mechanism hypotheses of sharkskin are generalized from different respects. This paper will improve the comprehension of the sharkskin fabrication method and expand biomimetic sharkskin technology into more applications in the fluid engineering.

  8. 1994 Baseline biological studies for the Device Assembly Facility at the Nevada Test Site

    SciTech Connect

    Townsend, Y.E.; Woodward, B.D.; Hunter, R.B.; Greger, P.D.; Saethre, M.B.

    1995-02-01

    This report describes environmental work performed at the Device Assembly Facility (DAF) in 1994 by the Basic Environmental Monitoring and Compliance Program (BECAMP). The DAF is located near the Mojave-Great Basin desert transition zone 27 km north of Mercury. The area immediately around the DAF building complex is a gentle slope cut by 1 to 3 m deep arroyos, and occupied by transitional vegetation. In 1994, construction activities were largely limited to work inside the perimeter fence. The DAF was still in a preoperational mode in 1994, and no nuclear materials were present. The DAF facilities were being occupied so there was water in the sewage settling pond, and the roads and lights were in use. Sampling activities in 1994 represent the first year in the proposed monitoring scheme. The proposed biological monitoring plan gives detailed experimental protocols. Plant, lizard, tortoise, small mammal, and bird surveys were performed in 1994. The authors briefly outline procedures employed in 1994. Studies performed on each taxon are reviewed separately then summarized in a concluding section.

  9. Testing Foundations of Biological Scaling Theory Using Automated Measurements of Vascular Networks.

    PubMed

    Newberry, Mitchell G; Ennis, Daniel B; Savage, Van M

    2015-08-01

    Scientists have long sought to understand how vascular networks supply blood and oxygen to cells throughout the body. Recent work focuses on principles that constrain how vessel size changes through branching generations from the aorta to capillaries and uses scaling exponents to quantify these changes. Prominent scaling theories predict that combinations of these exponents explain how metabolic, growth, and other biological rates vary with body size. Nevertheless, direct measurements of individual vessel segments have been limited because existing techniques for measuring vasculature are invasive, time consuming, and technically difficult. We developed software that extracts the length, radius, and connectivity of in vivo vessels from contrast-enhanced 3D Magnetic Resonance Angiography. Using data from 20 human subjects, we calculated scaling exponents by four methods-two derived from local properties of branching junctions and two from whole-network properties. Although these methods are often used interchangeably in the literature, we do not find general agreement between these methods, particularly for vessel lengths. Measurements for length of vessels also diverge from theoretical values, but those for radius show stronger agreement. Our results demonstrate that vascular network models cannot ignore certain complexities of real vascular systems and indicate the need to discover new principles regarding vessel lengths. PMID:26317654

  10. Effects of activated carbon amended sediment on biological responses in Chironomus riparius multi-generation testing.

    PubMed

    Nybom, Inna; Abel, Sebastian; Mäenpää, Kimmo; Akkanen, Jarkko

    2016-11-15

    The biological effects of activated carbon (AC) amendments in sediments were studied with the midge Chironomus riparius. The effects on larvae growth were studied using three different AC particles sizes (PAC: 90% <63μm, MAC: ø 63-200μm and GAC: ø 420-1700μm). The long- term effects of MAC were studied in an emergence experiment over two generations (P, F1), together with larvae growth experiment over three generations (P, F1, F2). Retarded growth and development of the larvae were observed in the two smallest particle sizes (PAC and MAC), as well as morphological changes in the gut wall microvilli layer studied from transmission electron micrographs. In addition, at high AC treatments the larvae reaching fourth instar stage were of a smaller size compared to the controls. With PAC treatment AC amendment dosages higher than 1% of sediment dry weight induced mortality. In the emergence experiment there was an indication of a delay in F1 generation emergence. Male dry weight (dw) in P generation was significantly reduced in the 2.5% MAC treatment. The effects of AC amendments were more obvious in the C. riparius larvae compared to the effects seen in emerging adults exposed to AC-amended sediment during the larval stage. PMID:27450330

  11. Synthesis and Biological Testing of Novel Glucosylated Epigallocatechin Gallate (EGCG) Derivatives.

    PubMed

    Zhang, Xin; Wang, Jing; Hu, Jiang-Miao; Huang, Ye-Wei; Wu, Xiao-Yun; Zi, Cheng-Ting; Wang, Xuan-Jun; Sheng, Jun

    2016-01-01

    Epigallocatechin gallate (EGCG) is the most abundant component of green tea catechins and has strong physiological activities. In this study, two novel EGCG glycosides (EGCG-G1 and EGCG-G2) were chemoselectively synthesized by a chemical modification strategy. Each of these EGCG glycosides underwent structure identification, and the structures were assigned as follows: epigallocatechin gallate-4''-O-β-d-glucopyranoside (EGCG-G1, 2) and epigallocatechin gallate-4',4''-O-β-d-gluco-pyranoside (EGCG-G2, 3). The EGCG glycosides were evaluated for their anticancer activity in vitro against two human breast cell lines (MCF-7 and MDA-MB-231) using MTT assays. The inhibition rate of EGCG glycosides (EGCG-G1 and EGCG-G2) is not obvious. The EGCG glycosides are more stable than EGCG in aqueous solutions, but exhibited decreasing antioxidant activity in the DPPH radical-scavenging assay (EGCG > EGCG-G2 > EGCG-G1). Additionally, the EGCG glycosides exhibited increased water solubility: EGCG-G2 and EGCG-G1 were 15 and 31 times as soluble EGCG, respectively. The EGCG glycosides appear to be useful, and further studies regarding their biological activity are in progress. PMID:27187321

  12. Testing Foundations of Biological Scaling Theory Using Automated Measurements of Vascular Networks

    PubMed Central

    Newberry, Mitchell G; Ennis, Daniel B; Savage, Van M

    2015-01-01

    Scientists have long sought to understand how vascular networks supply blood and oxygen to cells throughout the body. Recent work focuses on principles that constrain how vessel size changes through branching generations from the aorta to capillaries and uses scaling exponents to quantify these changes. Prominent scaling theories predict that combinations of these exponents explain how metabolic, growth, and other biological rates vary with body size. Nevertheless, direct measurements of individual vessel segments have been limited because existing techniques for measuring vasculature are invasive, time consuming, and technically difficult. We developed software that extracts the length, radius, and connectivity of in vivo vessels from contrast-enhanced 3D Magnetic Resonance Angiography. Using data from 20 human subjects, we calculated scaling exponents by four methods—two derived from local properties of branching junctions and two from whole-network properties. Although these methods are often used interchangeably in the literature, we do not find general agreement between these methods, particularly for vessel lengths. Measurements for length of vessels also diverge from theoretical values, but those for radius show stronger agreement. Our results demonstrate that vascular network models cannot ignore certain complexities of real vascular systems and indicate the need to discover new principles regarding vessel lengths. PMID:26317654

  13. Biologic surveys for the Sandia National Laboratories, Coyote Canyon Test Complex, Kirtland Air Force Base, Albuquerque, New Mexico

    SciTech Connect

    Sullivan, R.M.; Knight, P.J.

    1994-05-25

    This report provides results of a comprehensive biologic survey performed in Coyote Canyon Test Complex (CCTC), Sandia National Laboratories (SNL), Bernalillo County, New Mexico, which was conducted during the spring and summer of 1992 and 1993. CCTC is sited on land owned by the Department of Energy (DOE) and Kirtland Air Force Base and managed by SNL. The survey covered 3,760 acres of land, most of which is rarely disturbed by CCTC operations. Absence of grazing by livestock and possibly native ungulates, and relative to the general condition of private range lands throughout New Mexico, and relative to other grazing lands in central New Mexico. Widely dispersed, low intensity use by SNL as well as prohibition of grazing has probably contributed to abundance of special status species such as grama grass cactus within the CCTC area. This report evaluates threatened and endangered species found in the area, as well as comprehensive assessment of biologic habitats. Included are analyses of potential impacts and mitigative measures designed to reduce or eliminate potential impacts. Included is a summary of CCTC program and testing activities.

  14. Host range testing and biology of Abia sericea (Cimbicidae), a candidate for biological control of invasive teasels (Dipsacus spp.) in North America

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Invasive teasels (Dipsacus spp., Dipsacaceae) are widespread in the USA, being present in 43 states and listed as noxious in five. The cimbicid sawfly Abia sericea (L.) is under evaluation as a potential agent for biological control of teasels. The host range, biology, and life history of this ins...

  15. Engineering aspects of the experiment and results of animal tests. [Apollo 17 Biological Cosmic Ray Experiment

    NASA Technical Reports Server (NTRS)

    Look, B. C.; Tremor, J. W.; Barrows, W. F.; Zabower, H. R.; Suri, K.; Park, E. G., Jr.; Durso, J. A.; Leon, H. A.; Haymaker, W.; Lindberg, R. G.

    1975-01-01

    A closed passive system independent of support from the spacecraft or its crew was developed to house five pocket mice for their flight on Apollo XVII. The reaction of potassium superoxide with carbon dioxide and water vapor to produce oxygen provided a habitable atmosphere within the experiment package. The performance of the system and the ability of the mice to survive the key preflight tests gave reasonable assurance that the mice would also withstand the Apollo flight.-

  16. ``Test kit'' for detection of biologically important anions: A salicylidene-hydrazine based Schiff base

    NASA Astrophysics Data System (ADS)

    Dalapati, Sasanka; Alam, Md Akhtarul; Jana, Sankar; Karmakar, Saswati; Guchhait, Nikhil

    2013-02-01

    Test paper coated with Schiff base [(N,N/-bis(5-nitro-salicylidene)hydrazine] receptor 1 (host) can selectively detect fluoride and acetate ions (guest) by developing yellow color which can be detected by naked-eye both in aqueous-acetonitrile solution and in solid supported test kit. UV-vis spectral analysis shows that the absorption peaks at 288 and 345 nm of receptor 1 gradually decrease its initial intensity and new red shifted absorption bands at 397 nm and 455 nm gradually appear upon addition of increasing amount of F- and AcO- ions over several tested anions such as HPO4-, Cl, Br, I, NO3-, NO2-, HSO4-, HSO3-, and ClO4- in aqueous-acetonitrile solvent. The colorimetric test results and UV-vis spectral analysis are in well agreement with 1H NMR titration results in d6-DMSO solvent. The receptor 1 forms 1:2 stable complexes with F- and AcO- ions. However, similar kind of observation obtained from UV-vis titrations in presence of AcOH corresponds to 1:1 complexation ratio indicating the formation of H-bonding interaction between the receptor and anions (F- and AcO- ions). So, the observed 1:2 complexation ratio can only be explained on the basis of deprotonation (˜1 eqv.) and H-bonding (˜1 eqv.) interactions [1]. The ratiometric analysis of host-guest complexes corroborates well with the proposed theoretical model optimization at Density Functional Theory (DFT) level.

  17. System development and early biological tests in NASA's biomass production chamber

    NASA Technical Reports Server (NTRS)

    Wheeler, R. M.; Mackowiak, C. L.; Dreschel, T. W.; Sager, J. C.; Prince, R. P.; Knott, W. M.; Hinkle, C. R.; Strayer, R. F.

    1990-01-01

    The Biomass Production Chamber at Kennedy Space Center was constructed to conduct large scale plant growth studies for NASA's CELSS program. Over the past four years, physical systems and computer control software have been continually upgraded and the degree of atmospheric leakage from the chamber has decreased from about 40 to 5 percent of the total volume per day. Early tests conducted with a limited degree of closure showed that total crop (wheat) growth from the best trays was within 80 percent of reported optimal yields for similar light levels. Yields from subsequent tests under more tightly closed conditions have not been as good--up to only 65 percent of optimal yields. Yields appear to have decreased with increasing closure, yet potential problems exist in cultural techniques and further studies are warranted. With the ability to tightly seal the chamber, quantitative data were gathered on CO2 and water exchange rates. Results showed that stand photosynthesis and transpiration reached a peak near 25 days after planting, soon after full vegetative ground cover was established. In the final phase of testing when atmospheric closure was the highest, ethylene gas levels in the chamber rose from about 10 to nearly 120 ppb. Evidence suggests that the ethylene originated from the wheat plants themselves and may have caused an epinastic rolling of the leaves, but no apparent detrimental effects on whole plant function.

  18. Hardy-Weinberg Equilibrium Testing of Biological Ascertainment for Mendelian Randomization Studies

    PubMed Central

    Rodriguez, Santiago; Gaunt, Tom R.

    2009-01-01

    Mendelian randomization (MR) permits causal inference between exposures and a disease. It can be compared with randomized controlled trials. Whereas in a randomized controlled trial the randomization occurs at entry into the trial, in MR the randomization occurs during gamete formation and conception. Several factors, including time since conception and sampling variation, are relevant to the interpretation of an MR test. Particularly important is consideration of the “missingness” of genotypes that can be originated by chance, genotyping errors, or clinical ascertainment. Testing for Hardy-Weinberg equilibrium (HWE) is a genetic approach that permits evaluation of missingness. In this paper, the authors demonstrate evidence of nonconformity with HWE in real data. They also perform simulations to characterize the sensitivity of HWE tests to missingness. Unresolved missingness could lead to a false rejection of causality in an MR investigation of trait-disease association. These results indicate that large-scale studies, very high quality genotyping data, and detailed knowledge of the life-course genetics of the alleles/genotypes studied will largely mitigate this risk. The authors also present a Web program (http://www.oege.org/software/hwe-mr-calc.shtml) for estimating possible missingness and an approach to evaluating missingness under different genetic models. PMID:19126586

  19. Mesoscopic features of charge generation in organic semiconductors.

    PubMed

    Savoie, Brett M; Jackson, Nicholas E; Chen, Lin X; Marks, Tobin J; Ratner, Mark A

    2014-11-18

    CONSPECTUS: In the past two decades, organic materials have been extensively investigated by numerous research groups worldwide for implementation in organic photovoltaic (OPV) devices. The interest in organic semiconductors is spurred by their potential low cost and facile tunability, making OPV devices a potentially disruptive technology. To study OPV operating mechanisms is also to explore a knowledge gap in our general understanding of materials, because both the time scales (femtosecond to microsecond) and length scales (nanometer to micrometer) relevant to OPV functionality occupy a challenging and fascinating space between the traditional regimes of quantum chemistry and solid-state physics. New theoretical frameworks and computational tools are needed to bridge the aforementioned length and time scales, and they must satisfy the criteria of computational tractability for systems involving 10(4)-10(6) atoms, while also maintaining predictive utility. While this challenge is far from solved, advances in density functional theory (DFT) have allowed researchers to investigate the ground- and excited-state properties of many intermediate sized systems (10(2)-10(3) atoms) that provide the outlines of the larger problem. Results on these smaller systems are already sufficient to predict optical gaps and trends in valence band energies, correct erroneous interpretations of experimental data, and develop models for charge generation and transport in OPV devices. The active films of high-efficiency OPV devices are comprised of mesoscopic mixtures of electron donor (D) and electron acceptor (A) species, a "bulk-heterojunction" (BHJ) device, subject to variable degrees of structural disorder. Depending on the degree of intermolecular electronic coupling and energy level alignment, the spatial delocalization of photoexcitations and charge carriers can affect the dynamics of the solar cell. In this Account, we provide an overview of three pivotal characteristics of solar

  20. Shell structure and classical orbits in mesoscopic systems

    NASA Astrophysics Data System (ADS)

    Tanaka, Kaori

    The theme of this thesis is to understand global shell structure of a finite many-fermion system in connection with short periodic orbits of the corresponding classical system. It is the overall shell structure, or partly resolved quantum fluctuations in the density of states, that is often enough for describing various properties of a system of interacting particles. Through semiclassical periodic orbit theory, one can visualize quantum- mechanical phenomena in terms of simple classical orbits. It is particularly interesting to study this quantum- classical connection in the mesoscopic systems of simple metal clusters and quantum dots, as their size as well as the number of particles can be much larger than in such systems as atoms and nuclei. We first illustrate a direct connection between quantum shells and classical periodic orbits by means of a mathematical model of a cranked two-dimensional harmonic oscillator. The quantum spectrum exhibits intriguing features, forming the Farey fan pattern. Furthermore, there is an analogy between this cranked model and the system of charged particles in a uniform magnetic field. We then go on to examine the electronic shell structure of simple metal clusters and quantum dots under a homogeneous magnetic field, taking simple mean-field models for these systems. The so-called supershell structure, a long-range, beating modulation of the electronic shell structure of simple metal clusters, is a fascinating example which can be explained semiclassically in terms of short periodic orbits of high degeneracy. We study the effect of an external magnetic field on this supershell structure, assuming a spherical infinite well as a simple yet realistic mean-field potential for the valence electrons. It is found that there is little perceptible change in the supershells for experimentally feasible field strengths, and if yet stronger fields are assumed, the supershells get destroyed and new beat patterns appear. For semiclassical

  1. Directed self-assembly of mesoscopic components for led applications

    NASA Astrophysics Data System (ADS)

    Tkachenko, Anton

    Light-emitting diodes (LEDs) constitute a rapidly evolving and fast growing technology that promises to replace incandescent bulbs and compact fluorescent lights in many illumination applications. Large-area LED luminaires have a capability to transform lighting by providing a venue for development of smart lighting systems with additional benefits, such as visible light communications, sensing, health and productivity improvement through color temperature control, capability of creating "virtual sky" ceiling, and many others. The objective of this work is to explore directed self-assembly (DSA) approaches suitable for cost-effective assembly of large amount of LEDs and other mesoscopic (i.e. millimeter and sub-millimeter) electronic components and thus to enable manufacturing of smart lighting luminaires. Existing alternative approaches for assembly of semiconductor dies are examined including transfer printing, laser-assisted die transfer, and various directed self-assembly approaches using shape-recognition, magnetic and capillary forces, etc. After comparing their advantages and limitations, we developed two approaches to magnetic force-assisted DSA of LEDs on a large-area substrate in liquid and air medium. The first approach involves pick-up of buoyant and magnetic dies from the liquid surface onto the flexible substrate in a roll-to-roll process. The possibility of high-speed assembly of LED dies is demonstrated, but with a low yield due to the influence of the capillary force of the carrier liquid and the difficulty in ensuring reliable supply of dies to the assembly interface. To overcome the aforementioned challenges this process was modified to assemble the dies by sinking them onto the receiving substrate with a stencil mask on top, demonstrating LED assembly with a very low error rate but at a lower speed. A solder-assisted self-alignment is used to further improve placement precision and to ensure the proper orientation of the dies. The second

  2. Effectiveness of Treatment for Adolescent Substance Use: Is Biological Drug Testing Sufficient?

    PubMed Central

    Schuler, Megan S; Griffin, Beth Ann; Ramchand, Rajeev; Almirall, Daniel; McCaffrey, Daniel F

    2014-01-01

    Objective: The purpose of this study was to compare the relative effectiveness of three treatment modalities for adolescent substance use: biological drug screening (BDS), Motivational Enhancement Therapy–Cognitive Behavioral Therapy (MET/CBT5), and BDS combined with MET/CBT5, relative to no treatment. Method: This study comprised 5,186 adolescents (70% male) enrolled in substance use treatment and tracked through the Substance Abuse and Mental Health Services Administration’s Center for Substance Abuse Treatment’s database (BDS = 1,110; MET/CBT5 = 784; BDS combined with MET/CBT5 = 2,539; no treatment = 753). Outcomes of interest were substance use frequency and severity of substance use problems at 3, 6, and 12 months, as measured by the Global Appraisal of Individual Needs survey. Propensity score weighting was used to adjust for pretreatment covariate imbalances between groups. Weighted generalized linear models were used to estimate the impact of treatment on outcomes at 3, 6, and 12 months. Results: BDS, alone or in combination with MET/CBT5, was associated with improved substance use and substance problems outcomes. Relative to youth reporting no treatment services, the BDS group reported significantly lower substance use at all visits, with the observed difference increasing over time. BDS alone was associated with significantly fewer substance problems than BDS combined with MET/CBT5 at all visits and significantly lower use at 12 months. Conclusions: Our results demonstrate significant improvement on substance use outcomes associated with BDS and offer preliminary evidence that BDS, particularly standalone BDS, may be an effective form of drug treatment for adolescents. Further work, including randomized studies, should explore the optimal format of administering BDS to adolescents to achieve maximum effectiveness. PMID:24650830

  3. Embracing Biological and Methodological Variance in a New Approach to Pre-Clinical Stroke Testing.

    PubMed

    Kent, Thomas A; Mandava, Pitchaiah

    2016-08-01

    High-profile failures in stroke clinical trials have discouraged clinical translation of neuroprotectants. While there are several plausible explanations for these failures, we believe that the fundamental problem is the way clinical and pre-clinical studies are designed and analyzed for heterogeneous disorders such as stroke due to innate biological and methodological variability that current methods cannot capture. Recent efforts to address pre-clinical rigor and design, while important, are unable to account for variability present even in genetically homogenous rodents. Indeed, efforts to minimize variability may lessen the clinical relevance of pre-clinical models. We propose a new approach that recognizes the important role of baseline stroke severity and other factors in influencing outcome. Analogous to clinical trials, we propose reporting baseline factors that influence outcome and then adapting for the pre-clinical setting a method developed for clinical trial analysis where the influence of baseline factors is mathematically modeled and the variance quantified. A new therapy's effectiveness is then evaluated relative to the pooled outcome variance at its own baseline conditions. In this way, an objective threshold for robustness can be established that must be overcome to suggest its effectiveness when expanded to broader populations outside of the controlled environment of the PI's laboratory. The method is model neutral and subsumes sources of variance as reflected in baseline factors such as initial stroke severity. We propose that this new approach deserves consideration for providing an objective method to select agents worthy of the commitment of time and resources in translation to clinical trials. PMID:27018014

  4. Trait-Based Representation of Biological Nitrification: Model Development, Testing, and Predicted Community Composition

    PubMed Central

    Bouskill, Nicholas J.; Tang, Jinyun; Riley, William J.; Brodie, Eoin L.

    2012-01-01

    Trait-based microbial models show clear promise as tools to represent the diversity and activity of microorganisms across ecosystem gradients. These models parameterize specific traits that determine the relative fitness of an “organism” in a given environment, and represent the complexity of biological systems across temporal and spatial scales. In this study we introduce a microbial community trait-based modeling framework (MicroTrait) focused on nitrification (MicroTrait-N) that represents the ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) and nitrite-oxidizing bacteria (NOB) using traits related to enzyme kinetics and physiological properties. We used this model to predict nitrifier diversity, ammonia (NH3) oxidation rates, and nitrous oxide (N2O) production across pH, temperature, and substrate gradients. Predicted nitrifier diversity was predominantly determined by temperature and substrate availability, the latter was strongly influenced by pH. The model predicted that transient N2O production rates are maximized by a decoupling of the AOB and NOB communities, resulting in an accumulation and detoxification of nitrite to N2O by AOB. However, cumulative N2O production (over 6 month simulations) is maximized in a system where the relationship between AOB and NOB is maintained. When the reactions uncouple, the AOB become unstable and biomass declines rapidly, resulting in decreased NH3 oxidation and N2O production. We evaluated this model against site level chemical datasets from the interior of Alaska and accurately simulated NH3 oxidation rates and the relative ratio of AOA:AOB biomass. The predicted community structure and activity indicate (a) parameterization of a small number of traits may be sufficient to broadly characterize nitrifying community structure and (b) changing decadal trends in climate and edaphic conditions could impact nitrification rates in ways that are not captured by extant biogeochemical models. PMID

  5. Effects of supercypermethrin, a synthetic developmental pyrethroid, on four biological test systems.

    PubMed

    Miadoková, E; Vlcková, V; Dúhová, V; Trebatická, M; Garajová, L; Grolmus, J; Podstavková, S; Vlcek, D

    1992-01-01

    The genotoxic potential of the insecticide supercypermethrin, a second-generation pyrethroid, was studied on four different test systems. It was non-mutagenic to Salmonella typhimurium strains TA1535, TA100, TA1538, TA98 and TA97 in the presence and absence of S9 mixture. It induced gene conversion at the tryptophan locus and induced point mutations at the isoleucine locus in Saccharomyces cerevisiae cells. A slight increase in the frequency of aberrant anaphases and telophases in root tips of Hordeum vulgare and Vicia faba was observed, but no genotoxic effects were detected in Drosophila melanogaster. PMID:1381478

  6. Photodegradation of fluorene in aqueous solution: Identification and biological activity testing of degradation products.

    PubMed

    Kinani, Said; Souissi, Yasmine; Kinani, Aziz; Vujović, Svetlana; Aït-Aïssa, Sélim; Bouchonnet, Stéphane

    2016-04-15

    Degradation of fluorene under UV-vis irradiation in water was investigated and structural elucidation of the main photoproducts was achieved using gas chromatography coupled with mass spectrometry. Twenty-six photoproducts were structurally identified, mainly on the basis of electron ionization mass spectra interpretation. The main generated transformation products are hydroxy derivatives. Some secondary photoproducts including fluorenone, hydroxy fluorenone, 2-biphenyl carboxylic acid, biphenylene, methanol fluorene congeners and hydroxy fluorene dimers were also observed. A photodegradation pathway was suggested on the basis of the chemical structures of photoproducts. Fluorene as well as its main photoproducts for which chemical standards were commercially available were tested for their ability to elicit cytotoxic, estrogenic and dioxin-like activity by using in vitro cell-based bioassays. None of the tested compounds was cytotoxic at concentrations up to 100μM. However, 2-hydroxyfluorene and 3-hydroxyfluorene exerted significant estrogenic and dioxin-like activity on a concentration range of 3-30μM, while fluorene and 9-hydroxyfluorene were weakly or not active, respectively, in our assays. This supports the view that photodegradation processes can generate by-products of higher toxicological concern than the parent compound and strengthens the need to further identify transformation products in the aquatic environment. PMID:26987414

  7. Relationships among sediment chemistry, toxicity testing, and biology: What can large-scale monitoring teach us?

    SciTech Connect

    Summers, J.K.; Macauley, J.M.; Engle, V.D.; Malaeb, Z.

    1995-12-31

    The Environmental Monitoring and Assessment Program for Estuarine Resources has collected sediments from over 1,000 varying locations in the estuaries of the United States. At each of these sites, sediments are analyzed for bulk chemistry, tested for toxicity to Ampelisca abdita, and enumerated regarding benthic community structure and abundance. In addition, tissue residues have been examined for selected fish and shellfish species and toxicity testing has been completed at selected sites for alternative species. The statistical and ecological relationships among these indicators have been examined with regard to how they can used to identify the overall ecological condition of a site, an estuary, or populations of estuaries. Comparisons of these relationships among different regions of the country show major differences in the modes of exposure and response being prevalent in the Southeast and Gulf Coasts as compared to the Mid-Atlantic and West Coasts. While the extent of sediment contamination in the Southeast and Gulf estuaries appears to be similar to that of the Mid-Atlantic and California Coasts, the degree of contamination at contaminated sites is much greater in Mid-Atlantic estuaries. An examination of the primary contaminants suggests that the primary sources of contamination in the Mid-Atlantic are industrial and urban while the Southeast and Gulf estuaries are dominated by agricultural contaminants.

  8. Diagnosis of tetanus immunization status: multicenter assessment of a rapid biological test.

    PubMed

    Colombet, Isabelle; Saguez, Colette; Sanson-Le Pors, Marie-José; Coudert, Benoît; Chatellier, Gilles; Espinoza, Pierre

    2005-09-01

    Diagnosis of tetanus immunization status by medical interview of patients with wounds is poor. Many protected patients receive unnecessary vaccine or immunoglobulin, and unprotected patients may receive nothing. The aim of this study is to evaluate the feasibility and accuracy of the Tetanos Quick Stick (TQS) rapid finger prick stick test in the emergency department for determining immunization status. We designed a prospective multicenter study for blinded comparison of TQS with an enzyme-linked immunosorbent assay (ELISA). Adults referred for open wounds in 37 French hospital emergency departments had the TQS after receiving standard care (emergency-TQS). TQS was also performed in the hospital laboratory on total blood (blood/lab-TQS) and serum (serum/lab-TQS). ELISA was performed with the same blood sample at a central laboratory. We assessed concordance between emergency-TQS and blood/lab-TQS by the kappa test and the diagnostic accuracy (likelihood ratios) of medical interview, emergency-TQS, and lab-TQS. ELISA was positive in 94.6% of the 988 patients included. Concordance between blood/emergency-TQS and blood/lab-TQS results was moderate (kappa=0.6), with a high proportion of inconclusive blood/emergency-TQS tests (9.8%). Likelihood ratios for immunization were 3.0 (95% confidence interval [CI], 1.8 to 5.1), 36.6 (95% CI, 5.3 to 255.3), 89.1 (95% CI, 5.6 to 1,405.0), and 92.7 (95% CI, 5.9 to 1,462.0) for medical interview, blood/emergency-TQS, blood/lab-TQS, and serum/lab-TQS, respectively. The sensitivity of the blood/emergency-TQS was 76.7%, and the specificity was 98% by reference to the ELISA. TQS use in the emergency room could make tetanus prevention more accurate if its technical feasibility were improved, and our assessment will be supplemented by a cost effectiveness study. PMID:16148171

  9. Diagnosis of Tetanus Immunization Status: Multicenter Assessment of a Rapid Biological Test

    PubMed Central

    Colombet, Isabelle; Saguez, Colette; Sanson-Le Pors, Marie-José; Coudert, Benoît; Chatellier, Gilles; Espinoza, Pierre

    2005-01-01

    Diagnosis of tetanus immunization status by medical interview of patients with wounds is poor. Many protected patients receive unnecessary vaccine or immunoglobulin, and unprotected patients may receive nothing. The aim of this study is to evaluate the feasibility and accuracy of the Tetanos Quick Stick (TQS) rapid finger prick stick test in the emergency department for determining immunization status. We designed a prospective multicenter study for blinded comparison of TQS with an enzyme-linked immunosorbent assay (ELISA). Adults referred for open wounds in 37 French hospital emergency departments had the TQS after receiving standard care (emergency-TQS). TQS was also performed in the hospital laboratory on total blood (blood/lab-TQS) and serum (serum/lab-TQS). ELISA was performed with the same blood sample at a central laboratory. We assessed concordance between emergency-TQS and blood/lab-TQS by the kappa test and the diagnostic accuracy (likelihood ratios) of medical interview, emergency-TQS, and lab-TQS. ELISA was positive in 94.6% of the 988 patients included. Concordance between blood/emergency-TQS and blood/lab-TQS results was moderate (κ = 0.6), with a high proportion of inconclusive blood/emergency-TQS tests (9.8%). Likelihood ratios for immunization were 3.0 (95% confidence interval [CI], 1.8 to 5.1), 36.6 (95% CI, 5.3 to 255.3), 89.1 (95% CI, 5.6 to 1,405.0), and 92.7 (95% CI, 5.9 to 1,462.0) for medical interview, blood/emergency-TQS, blood/lab-TQS, and serum/lab-TQS, respectively. The sensitivity of the blood/emergency-TQS was 76.7%, and the specificity was 98% by reference to the ELISA. TQS use in the emergency room could make tetanus prevention more accurate if its technical feasibility were improved, and our assessment will be supplemented by a cost effectiveness study. PMID:16148171

  10. Mesoscopic modeling of cancer photothermal therapy using single-walled carbon nanotubes and near infrared radiation: insights through an off-lattice Monte Carlo approach

    NASA Astrophysics Data System (ADS)

    Gong, Feng; Hongyan, Zhang; Papavassiliou, Dimitrios V.; Bui, Khoa; Lim, Christina; Duong, Hai M.

    2014-05-01

    Single-walled carbon nanotubes (SWNTs) are promising heating agents in cancer photothermal therapy when under near infrared radiation, yet few efforts have been focused on the quantitative understanding of the photothermal energy conversion in biological systems. In this article, a mesoscopic study that takes into account SWNT morphologies (diameter and aspect ratio) and dispersions (orientation and concentration), as well as thermal boundary resistance, is performed by means of an off-lattice Monte Carlo simulation. Results indicate that SWNTs with orientation perpendicular to the laser, smaller diameter and better dispersion have higher heating efficiency in cancer photothermal therapy. Thermal boundary resistances greatly inhibit thermal energy transfer away from SWNTs, thereby affecting their heating efficiency. Through appropriate interfacial modification around SWNTs, compared to the surrounding healthy tissue, a higher temperature of the cancer cell can be achieved, resulting in more effective cancer photothermal therapy. These findings promise to bridge the gap between macroscopic and microscopic computational studies of cancer photothermal therapy.

  11. Determination of MBT-waste reactivity - An infrared spectroscopic and multivariate statistical approach to identify and avoid failures of biological tests.

    PubMed

    Böhm, K; Smidt, E; Binner, E; Schwanninger, M; Tintner, J; Lechner, P

    2010-04-01

    The Austrian Landfill Ordinance provides limit values regarding the reactivity for the disposal of mechanically biologically treated (MBT) waste before landfilling. The potential reactivity determined by biological tests according to the Austrian Standards (OENORM S 2027 1-2) can be underestimated if the microbial community is affected by environmental conditions. New analytical tools have been developed as an alternative to error-prone and time-consuming biological tests. Fourier Transform Infrared (FT-IR) spectroscopy in association with Partial Least Squares Regression (PLS-R) was used to predict the reactivity parameters respiration activity (RA(4)) and gas generation sum (GS(21)) as well as to detect errors resulting from inhibiting effects on biological tests. For this purpose 250 MBT-waste samples from different Austrian MBT-plants were investigated using FT-IR spectroscopy in the mid (MIR) and near infrared (NIR) area and biological tests. Spectroscopic results were compared with those from biological tests. Arising problems caused by interferences of RA(4) and GS(21) are discussed. It is shown that FT-IR spectroscopy predicts RA(4) and GS(21) reliably to assess stability of MBT-waste materials and to detect errors. PMID:19854633

  12. Biological monitoring of toxic pollutants in ocean waters: physiological stress testing of bay and coastal mussels in California

    SciTech Connect

    Severeid, R.L.

    1983-01-01

    This report describes the results of the first two years of a study designed to assess the health of marine ecosystems; the Biological Effects Assessment Study. Using the mussel (Mytilus sp.) as a representative marine organism, the effects of exposure to chronic, low levels of toxic trace metals, pesticides and petroleum hydrocarbons were determined by a method of physiological stress testing, Scope for Growth. The Scope for Growth (SFG) index is the theoretical amount of energy available to an organism for growth and reproduction after maintenance requirements are taken into account. The more energy available, the higher the index, the healthier the organism. Low or negative values indicate the organism is stressed. Four commonly measured physiological parameters are used to calculate the SFG index: oxygen consumption, ammonia excretion, assimilation efficiency, and clearance rate. The report includes the results of the first two years of the Biological Effects Assessment Study, the background for State Water Resources Control Board's involvement in the field of pollution monitoring, a brief discussion of the methods, materials and calculations used to determine the SFG index, a discussion of the factors that influence the Scope for Growth index, and the future of the program.

  13. Field scale testing of a hyperfiltration unit for removal of creosote and pentachlorophenol from ground water: Chemical and biological assessment

    SciTech Connect

    Middaugh, D.P.; Thomas, R.L.; Lantz, S.E.; Heard, C.S.; Mueller, J.G.

    1994-01-01

    Chemical analyses and biological response data were used to assess the efficacy of a field-scale hyperfiltration unit in the removal of polycyclic aromatic hydrocarbons (PAHs) and other organic compounds from creosote- and pentachlorophenol (PCP)-contaminated ground water recovered from the former American Creosote Works in Escambia County, Pensacola, Florida. The hyperfiltration unit consisted of 4 modules containing porous stainless steel tubes which were coated with a formed-in-place zirconium hydrous oxide-polyacrylic acid (ZOPA) membrane. A 5-fold concentration of the feedwater (80% volume reduction) with up to 97% removal of high molecular weight PAHs was achieved during pre-demonstration and field-demonstration runs of the hyperfiltration unit. Toxicological and teratogenic data for embryonic inland silversides, Menidia beryllina, indicated that 100, 10 and 1% solutions of the ground water sample used in the pre-demonstration run caused statistically significant (p < or - 0.05) biological responses when compared to controls. Permeates from both runs, diluted to 1%, met the pre-condition of non-toxic responses in 48h tests with Ceriodaphnia dubia. Meeting this requirement allowed for discharge of diluted permeate into the county's sanitary sewerage collector system.

  14. Environmental Technology Verification: Supplement to Test/QA Plan for Biological and Aerosol Testing of General Ventilation Air Cleaners; Bioaerosol Inactivation Efficiency by HVAC In-Duct Ultraviolet Light Air Cleaners

    EPA Science Inventory

    The Air Pollution Control Technology Verification Center has selected general ventilation air cleaners as a technology area. The Generic Verification Protocol for Biological and Aerosol Testing of General Ventilation Air Cleaners is on the Environmental Technology Verification we...

  15. Herpes Murine Model as a Biological Assay to Test Dialyzable Leukocyte Extracts Activity

    PubMed Central

    Salinas-Jazmín, Nohemí; Estrada-Parra, Sergio; Becerril-García, Miguel Angel; Limón-Flores, Alberto Yairh; Vázquez-Leyva, Said; Pavón, Lenin; Velasco-Velázquez, Marco Antonio; Pérez-Tapia, Sonia Mayra

    2015-01-01

    Human dialyzable leukocyte extracts (DLEs) are heterogeneous mixtures of low-molecular-weight peptides that are released on disruption of peripheral blood leukocytes from healthy donors. DLEs improve clinical responses in infections, allergies, cancer, and immunodeficiencies. Transferon is a human DLE that has been registered as a hemoderivate by Mexican health authorities and commercialized nationally. To develop an animal model that could be used routinely as a quality control assay for Transferon, we standardized and validated a murine model of cutaneous HSV-1 infection. Using this model, we evaluated the activity of 27 Transferon batches. All batches improved the survival of HSV-1-infected mice, wherein average survival rose from 20.9% in control mice to 59.6% in Transferon-treated mice. The activity of Transferon correlated with increased serum levels of IFN-γ and reduced IL-6 and TNF-α concentrations. Our results demonstrate that (i) this mouse model of cutaneous herpes can be used to examine the activity of DLEs, such as Transferon; (ii) the assay can be used as a routine test for batch release; (iii) Transferon is produced with high homogeneity between batches; (iv) Transferon does not have direct virucidal, cytoprotective, or antireplicative effects; and (v) the protective effect of Transferon in vivo correlates with changes in serum cytokines. PMID:25984538

  16. Biology Notes.

    ERIC Educational Resources Information Center

    School Science Review, 1983

    1983-01-01

    Describes laboratory procedures, demonstrations, and classroom activities/materials, including chi-square tests on a microcomputer, an integrated biology game, microscope slides of leaf stomata, culturing soil nematodes, technique for watering locust egg-laying tubes, hazards of biological chemicals (such as benzene, benzidene, calchicine,…

  17. Tests of a practical visible-NIR imaging Fourier transform spectrometer for biological and chemical fluorescence emission measurements.

    PubMed

    Li, Jianping; Chan, Robert K Y; Wang, Xuzhu

    2009-11-01

    An imaging Fourier transform spectrometer (IFTS) designed for fluorescence emission measurements is reported. The spectral range extension from NIR to visible of the system is realized by using a simple and low-cost optical beam-folding position-tracking technique. Spectral resolution as high as 9.78cm(-1)(0.4nm at 632.8nm) and maximum image resolution up to 300x300 pixels are proved by the system tests on its optical performances. Imaging fluorescence spectra acquisition of quantum dot clusters and single 200nm diameter fluorescent beads have demonstrated the system's potential for high throughput imaging spectroscopic measurements of fluorescent biological and chemical samples. PMID:19997347

  18. A mathematical model for the interpretation of nuclear bomb test derived 14C incorporation in biological systems

    NASA Astrophysics Data System (ADS)

    Bernard, Samuel; Frisén, Jonas; Spalding, Kirsty L.

    2010-04-01

    Human tissues continually replace dying cells with newborn cells. However, the rate of renewal varies by orders of magnitudes between blood cells, which are renewed every day and neurons, for which renewal is non-existent or limited to specific regions of the brain. Between those extreme are many tissues that turnover on a time scale of years, although no direct measurements have been done. We present here a mathematical method to estimate cell turnover in slowly renewing biological systems. Age distribution of DNA can be estimated from the integration of radiocarbon derived from nuclear bomb-testing during the cold war (1955-1963). For slowly renewing tissues, this method provides a better estimate of the average age of the tissue than direct estimates from the bomb-curve. Moreover, death, birth and turnover rates can be estimated. We highlight this method with data from human fat cells.

  19. Biologic overview for the Nevada Nuclear Waste Storage Investigations, Nevada Test Site, Nye County, Nevada

    SciTech Connect

    Collins, E.; O`Farrell, T.P.; Rhoads, W.A.

    1982-01-01

    The Nevada Nuclear Waste Storage Investigations project study area includes five major vegetation associations characteristic of the transition between the northern extent of the Mojave Desert and the southern extent of the Great Basin Desert. A total of 32 species of reptiles, 66 species of birds, and 46 species of mammals are known to occur within these associations elsewhere on the Nevada Test Site. Ten species of plants, and the mule deer, wild horse, feral burro, and desert tortoise were defined as possible sensitive species because they are protected by federal and state regulations, or are being considered for such protection. The major agricultural resources of southern Nye County included 737,000 acres of public grazing land managed by the Bureau of Land Management, and 9500 acres of irrigated crop land located in the Beatty/Oasis valleys, the Amargosa Valley, and Ash Meadows. Range lands are of poor quality. Alfalfa and cotton are the major crops along with small amounts of grains, Sudan grass, turf, fruits, and melons. The largest impacts to known ecosystems are expected to result from: extensive disturbances associated with construction of roads, seismic lines, drilling pads, and surface facilities; storage and leaching of mined spoils; disposal of water; off-road vehicle travel; and, over several hundred years, elevated soil temperatures. Significant impacts to off-site areas such as Ash Meadows are anticipated if new residential developments are built there to accommodate an increased work force. Several species of concern and their essential habitats are located at Ash Meadows. Available literature contained sufficient baseline information to assess potential impacts of the proposed project on an area-wide basis. It was inadequate to support analysis of potential impacts on specific locations selected for site characterization studies, mining an exploratory shaft, or the siting and operation of a repository.

  20. Bottle Biology.

    ERIC Educational Resources Information Center

    CSTA Journal, 1995

    1995-01-01

    Provides hands-on biology activities using plastic bottles that allow students to become engaged in asking questions, creating experiments, testing hypotheses, and generating answers. Activities explore terrestrial and aquatic systems. (MKR)

  1. DNA Fingerprinting To Improve Data Collection Efficiency and Yield in a Host-Specificity Test of a Weed Biological Control Candidate

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An open-field test was conducted in southern France to assess the host-specificity of Ceratapion basicorne, a candidate for biological control of yellow starthistle (Centaurea solstitialis; YST). Test plants were infested by naturally occurring populations of C. basicorne but were also exposed to s...

  2. Mesoscopic Superposition States Generated by Synthetic Spin-Orbit Interaction in Fock-State Lattices

    NASA Astrophysics Data System (ADS)

    Wang, Da-Wei; Cai, Han; Liu, Ren-Bao; Scully, Marlan O.

    2016-06-01

    Mesoscopic superposition states of photons can be prepared in three cavities interacting with the same two-level atom. By periodically modulating the three cavity frequencies around the transition frequency of the atom with a 2 π /3 phase difference, the time reversal symmetry is broken and an optical circulator is generated with chiralities depending on the quantum state of the atom. A superposition of the atomic states can guide photons from one cavity to a mesoscopic superposition of the other two cavities. The physics can be understood in a finite spin-orbit-coupled Fock-state lattice where the atom and the cavities carry the spin and the orbit degrees of freedom, respectively. This scheme can be realized in circuit QED architectures and provides a new platform for exploring quantum information and topological physics in novel lattices.

  3. Mesoscopic Superposition States Generated by Synthetic Spin-Orbit Interaction in Fock-State Lattices.

    PubMed

    Wang, Da-Wei; Cai, Han; Liu, Ren-Bao; Scully, Marlan O

    2016-06-01

    Mesoscopic superposition states of photons can be prepared in three cavities interacting with the same two-level atom. By periodically modulating the three cavity frequencies around the transition frequency of the atom with a 2π/3 phase difference, the time reversal symmetry is broken and an optical circulator is generated with chiralities depending on the quantum state of the atom. A superposition of the atomic states can guide photons from one cavity to a mesoscopic superposition of the other two cavities. The physics can be understood in a finite spin-orbit-coupled Fock-state lattice where the atom and the cavities carry the spin and the orbit degrees of freedom, respectively. This scheme can be realized in circuit QED architectures and provides a new platform for exploring quantum information and topological physics in novel lattices. PMID:27314706

  4. Multiparticle Correlations in Mesoscopic Scattering: Boson Sampling, Birthday Paradox, and Hong-Ou-Mandel Profiles

    NASA Astrophysics Data System (ADS)

    Urbina, Juan-Diego; Kuipers, Jack; Matsumoto, Sho; Hummel, Quirin; Richter, Klaus

    2016-03-01

    The interplay between single-particle interference and quantum indistinguishability leads to signature correlations in many-body scattering. We uncover these with a semiclassical calculation of the transmission probabilities through mesoscopic cavities for systems of noninteracting particles. For chaotic cavities we provide the universal form of the first two moments of the transmission probabilities over ensembles of random unitary matrices, including weak localization and dephasing effects. If the incoming many-body state consists of two macroscopically occupied wave packets, their time delay drives a quantum-classical transition along a boundary determined by the bosonic birthday paradox. Mesoscopic chaotic scattering of Bose-Einstein condensates is, then, a realistic candidate to build a boson sampler and to observe the macroscopic Hong-Ou-Mandel effect.

  5. Puzzling electron behavior analogous to the Braess paradox in a mesoscopic networ

    NASA Astrophysics Data System (ADS)

    Toussaint, Sébastien; Faniel, Sébastien; Martins, Frederico; Pala, Marco; Desplanque, Ludovic; Wallart, Xavier; Huant, Serge; Sellier, Hermann; Bayot, Vincent; Hackens, Benoit

    A counterintuitive behavior analogous to the Braess paradox is encountered in a two-terminal mesoscopic network patterned in a two-dimensional electron system (2DES). Decreasing locally the electron density of one channel in the network paradoxically leads to an increased network conductance. Our scanning gate microscopy experiments reveals this puzzling conductance variation, thanks to tip-induced localized modifications of electron flow throughout the network's channels at low temperature, in the ballistic and coherent regime of transport. We compare the amplitude of the measured anomalous conductance variation with conductance changes induced by other mechanisms at play in the mesoscopic network, such as interference phenomena between different paths, and Coulomb blockade due to disorder-induced localized states. The robustness of this puzzling behavior is inspected by varying the global 2DES density, magnetic field and temperature S.T. acknowledges support from the Belgian FRS-FNRS (FRIA).

  6. Puzzling electron behavior analogous to the Braess paradox in a mesoscopic network

    NASA Astrophysics Data System (ADS)

    Toussaint, Sébastien; Faniel, Sébastien; Martins, Frederico; Pala, Marco; Desplanque, Ludovic; Wallart, Xavier; Huant, Serge; Sellier, Hermann; Bayot, Vincent; Hackens, Benoit

    A counterintuitive behavior analogous to the Braess paradox is encountered in a two-terminal mesoscopic network patterned in a two-dimensional electron system (2DES). Decreasing locally the electron density of one channel in the network paradoxically leads to an increased network conductance. Our scanning gate microscopy experiments reveals this puzzling conductance variation, thanks to tip-induced localized modifications of electron flow throughout the network's channels at low temperature, in the ballistic and coherent regime of transport. We compare the amplitude of the measured anomalous conductance variation with conductance changes induced by other mechanisms at play in the mesoscopic network, such as interference phenomena between different paths, and Coulomb blockade due to disorder-induced localized states. The robustness of this puzzling behavior is inspected by varying the global 2DES density, magnetic field and temperature. S.T. acknowledges support from the Belgian FRS-FNRS (FRIA).

  7. Quantization, coherent states and geometric phases of a generalized nonstationary mesoscopic RLC circuit

    NASA Astrophysics Data System (ADS)

    Pedrosa, Inácio A.; Melo, Jilvan L.; Salatiel, Sadoque

    2014-11-01

    We present an alternative quantum treatment for a generalized mesoscopic RLC circuit with time-dependent resistance, inductance and capacitance. Taking advantage of the Lewis and Riesenfeld quantum invariant method and using quadratic invariants we obtain exact nonstationary Schrödinger states for this electromagnetic oscillation system. Afterwards, we construct coherent and squeezed states for the quantized RLC circuit and employ them to investigate some of the system's quantum properties, such as quantum fluctuations of the charge and the magnetic flux and the corresponding uncertainty product. In addition, we derive the geometric, dynamical and Berry phases for this nonstationary mesoscopic circuit. Finally we evaluate the dynamical and Berry phases for three special circuits. Surprisingly, we find identical expressions for the dynamical phase and the same formulae for the Berry's phase.

  8. Mesoscopic Hamiltonian for the fluctuations of adsorbed Lennard-Jones liquid films.

    PubMed

    Fernández, Eva M; Chacón, Enrique; MacDowell, Luis G; Tarazona, Pedro

    2015-06-01

    We use Monte Carlo simulations of a Lennard-Jones fluid adsorbed on a short-range planar wall substrate to study the fluctuations in the thickness of the wetting layer, and we get a quantitative and consistent characterization of their mesoscopic Hamiltonian, H[ξ]. We have observed important finite-size effects, which were hampering the analysis of previous results obtained with smaller systems. The results presented here support an appealing simple functional form for H[ξ], close but not exactly equal to the theoretical nonlocal proposal made on the basis a generic density-functional analysis by Parry and coworkers. We have analyzed systems under different wetting conditions, as a proof of principle for a method that provides a quantitative bridge between the molecular interactions and the phenomenology of wetting films at mesoscopic scales. PMID:26172722

  9. Hexatic and mesoscopic phases in a 2D quantum coulomb system.

    PubMed

    Clark, Bryan K; Casula, Michele; Ceperley, D M

    2009-07-31

    We study the Wigner crystal melting in a two-dimensional quantum system of distinguishable particles interacting via the 1/r Coulomb potential. We use quantum Monte Carlo methods to calculate its phase diagram, locate the Wigner crystal region, and analyze its instabilities towards the liquid phase. We discuss the role of quantum effects in the critical behavior of the system, and compare our numerical results with the classical theory of melting, and the microemulsion theory of frustrated Coulomb systems. We find a Pomeranchuk effect much larger then in solid helium. In addition, we find that the exponent for the algebraic decay of the hexatic phase differs significantly from the Kosterilitz-Thouless theory of melting. We search for the existence of mesoscopic phases and find evidence of metastable bubbles but no mesoscopic phase that is stable in equilibrium. PMID:19792514

  10. Mesoscopic analysis of Gibbs' criterion for sessile nanodroplets on trapezoidal substrates.

    PubMed

    Dutka, F; Napiórkowski, M; Dietrich, S

    2012-02-14

    By taking into account precursor films accompanying nanodroplets on trapezoidal substrates we show that on a mesoscopic level of description one does not observe the phenomenon of liquid-gas-substrate contact line pinning at substrate edges. This phenomenon is present in a macroscopic description and leads to non-unique contact angles which can take values within a range determined by the so-called Gibbs' criterion. Upon increasing the volume of the nanodroplet the apparent contact angle evaluated within the mesoscopic approach changes continuously between two limiting values fulfilling Gibbs' criterion, while the contact line moves smoothly across the edge of the trapezoidal substrate. The spatial extent of the range of positions of the contact line, corresponding to the variations of the contact angle between the values given by Gibbs' criterion, is of the order of ten fluid particle diameters. PMID:22360210

  11. Spectroscopy and Thermometry of Drumhead Modes in a Mesoscopic Trapped-Ion Crystal using Entanglement

    NASA Astrophysics Data System (ADS)

    Sawyer, Brian; Britton, Joseph; Keith, Adam; Wang, Joseph; Freericks, James; Uys, Hermann; Biercuk, Michael; Bollinger, John

    2012-06-01

    Studies of quantum mechanics at intermediate scales between microscopic and mesoscopic regimes have recently focused on the observation of quantum coherent phenomena in optomechanical systems. We demonstrate spectroscopy and thermometry of individual motional modes in a mesoscopic 2D ion array using entanglement-induced decoherence as a method of transduction. Our system is a ˜400 μm-diameter planar crystal of several hundred ^9Be^+ ions exhibiting complex drumhead modes in the confining potential of a Penning trap. Exploiting precise control over the ^9Be^+ valence electron spins, we apply a homogeneous spin-dependent optical dipole force to excite arbitrary transverse modes with an effective wavelength approaching the interparticle spacing (˜20 μm). Center-of-mass displacements of ˜120 pm are detected via entanglement of spin and motional degrees of freedom.

  12. Boundary scattering in quasi-ballistic graphene/hexagonal boron nitride mesoscopic wires

    NASA Astrophysics Data System (ADS)

    Iguchi, Kazuyuki; Masubuchi, Satoru; Yamaguchi, Takehiro; Ohnuki, Masahiro; Watanabe, Kenji; Taniguchi, Takashi; Machida, Tomoki

    2012-02-01

    In a quasi-ballistic transport regime where the mean free path is larger than the width of conduction channel, diffusive boundary scattering results in an anomalous positive magnetoresistance due to a megnetic commensurability effect between cyclotron motion and sample width. In this work, we fabricate a high-mobility two terminal graphene mesoscopic wire on hexagonal boron nitride with a mean free path comparable to sample width ˜ 1 μm. Magnetoresistance of the graphene mesoscopic wire shows a peak structure at a magnetic field which scales with the ratio of the cyclotron radius Rc to the wire width w. The peak field increases with back-gate voltage as a consequence that the ratio w/Rc is modified due to the change in Rc. These results indicate the quasi-ballistic transport and diffusive boundary scattering in graphene on hexagonal boron nitride.

  13. Density-dependent thermopower oscillations in mesoscopic two-dimensional electron gases

    NASA Astrophysics Data System (ADS)

    Narayan, Vijay; Kogan, Eugene; Ford, Chris; Pepper, Michael; Kaveh, Moshe; Griffiths, Jonathan; Jones, Geb; Beere, Harvey; Ritchie, Dave

    2014-08-01

    We present thermopower S and resistance R measurements on GaAs-based mesoscopic two-dimensional electron gases as functions of the electron density ns. At high ns we observe good agreement between the measured S and SMOTT, the Mott prediction for a non-interacting metal. As ns is lowered, we observe a crossover from Mott-like behaviour to that where S shows strong oscillations and even sign changes. Remarkably, there are absolutely no features in R corresponding to those in S. In fact, R is devoid of even any universal conductance fluctuations. A statistical analysis of the thermopower oscillations from two devices of dissimilar dimensions suggest a universal nature of the oscillations. We critically examine whether they can be mesoscopic fluctuations of the kind described by Lesovik and Khmelnitskii (1988 Sov. Phys. JETP 67 957).

  14. Phoretic self-propulsion: a mesoscopic description of reaction dynamics that powers motion

    NASA Astrophysics Data System (ADS)

    de Buyl, Pierre; Kapral, Raymond

    2013-01-01

    The fabrication of synthetic self-propelled particles and the experimental investigations of their dynamics have stimulated interest in self-generated phoretic effects that propel nano- and micron-scale objects. Theoretical modeling of these phenomena is often based on a continuum description of the solvent for different phoretic propulsion mechanisms, including, self-electrophoresis, self-diffusiophoresis and self-thermophoresis. The work in this paper considers various types of catalytic chemical reaction at the motor surface and in the bulk fluid that come into play in mesoscopic descriptions of the dynamics. The formulation is illustrated by developing the mesoscopic reaction dynamics for exothermic and dissociation reactions that are used to power motor motion. The results of simulations of the self-propelled dynamics of composite Janus particles by these mechanisms are presented.

  15. Spectrum and properties of mesoscopic surface-coupled phonons in rectangular wires

    NASA Astrophysics Data System (ADS)

    Patamia, Steven Eugene

    This dissertation presents original analytical derivations of the propagating modes of coupled mesoscopic phonons in an isotropic rectangular wire with stress-free surfaces. Incidental to the derivations, novel consequences of the derived cutoff modes are presented as they affect the low-energy heat conductance of such wires, or indeed any property that depends upon the dimensionality of the phase space within which the modes reside. Owing to nonseparability of the free-surface boundary conditions, an analytic description of coupled mesoscopic modes has heretofore been presumed to be underivable. Results presented herein show that the mode spectrum of coupled mesoscopic phonons is both subtle and rich, but considerable success in their analytic derivation is achieved. Using numerical methods developed for resonance problems, at least one contemporary researcher has purported to exhibit the lowest dispersion branches of propagating mesoscopic phonon modes in GaAs---which is not isotropic. The accuracy of these branches has not been measured, but they bear a qualitative consistency with isotropic modes derived herein. Since before the beginning of the 20th century, analytical solutions have been known for the infinite thin plate and even the case of waveguides with circular cross sections. Solutions for these special cases take the form of transcendental relations among the wavenumber and boundary parameters, but the underlying wavefunctions are separable in the coordinates. The analytical results presented herein for the general rectangular case involve nonseparable solutions whose separable components do not individually satisfy the boundary conditions. These solutions also take the form of transcendental relations, but there are sets of transcendental relations for each family of the cases that partition the problem. Consequently, the eigenspectrum, while defined by exact forms, must be enumerated by identifying plotted intersections of the root families of these

  16. Dispersion of PMMA-grafted, mesoscopic iron-oxide rods in polymer films.

    PubMed

    Ferrier, Robert C; Huang, Yun; Ohno, Kohji; Composto, Russell J

    2016-03-01

    This study investigates the parameters that affect the dispersion of polymer grafted mesoscopic iron-oxide rods (FeMRs) in polymer matrices. FeMRs (212 nm long by 36 nm in diameter) are grafted with poly(methyl methacrylate) (PMMA) at three different brush molecular weights: 3.7 kg mol(-1), 32 kg mol(-1), and 160 kg mol(-1). Each FeMR sample was cast in a polymer thin film consisting of either PMMA or poly(ethylene oxide) (PEO) each at a molecular weight much higher or much lower than the brush molecular weight. We find that the FeMRs with 160 kg mol(-1) brush disperse in all matrices while the FeMRs with 32 kg mol(-1) and 3.7 kg mol(-1) brushes aggregate in all matrices. We perform simple free energy calculations, taking into account steric repulsion from the brush and van der Waals attraction between FeMRs. We find that there is a barrier for aggregation for the FeMRs with the largest brush, while there is no barrier for the other FeMRs. Therefore, for these mesoscopic particles, the brush size is the main factor that determines the dispersion state of FeMRs in polymer matrices with athermal or weakly attractive brush-matrix interactions. These studies provide new insight into the mechanisms that affect dispersion in polymer matrices of mesoscopic particles and therefore guide the design of composite films with well-dispersed mesoscopic particles. PMID:26908174

  17. Mesoscopic transport and interferometry with wave packets of ultracold atoms: Effects of quantum coherence and interactions

    SciTech Connect

    Das, Kunal K.

    2011-09-15

    We propose a way to simulate mesoscopic transport processes with counterpropagating wave packets of ultracold atoms in quasi-one-dimensional (1D) waveguides and show quantitative agreement with analytical results. The method allows the study of a broad range of transport processes at the level of individual modes, not possible in electronic systems. Typically suppressed effects of quantum coherence become manifest, along with the effects of tunable interactions, which can be used to develop a simpler type of sensitive atom interferometer.

  18. Observation of Paramagnetic Supercurrent in Mesoscopic Superconducting Rings and Disks Using Multiple-Small Method

    NASA Astrophysics Data System (ADS)

    Kanda, A.; Baelus, B. J.; Peeters, F. M.; Kadowaki, K.; Ootuka, Y.

    2005-08-01

    Responses of mesoscopic superconducting rings and disks to perpendicular magnetic fields are studied by using the multiple-small-tunnel-junction method, in which transport properties of several small tunnel junctions attached to the sample are measured simultaneously. This allows us for a direct experimental observation of the paramagnetic supercurrent, which is closely related to the paramagnetic Meissner effect. The results are compared with numerical results based on the nonlinear Ginzburg-Landau theory.

  19. Charge distributions due to paramagnetism and diamagnetism in thin mesoscopic superconducting rings [rapid communication

    NASA Astrophysics Data System (ADS)

    Zhu, Bao-He; Zhou, Shi-Ping; Zha, Guo-Qiao; Yang, Kui

    2005-05-01

    The charge distribution in a thin mesoscopic superconducting ring is investigated by the phenomenological Ginzburg Landau theory. Considering a ring in a giant vortex state, we find that the charge near the inner radius may change its sign from negative to positive with increasing the applied field. It is also found that the charge distributions are due to the competition between the paramagnetic Meissner effect and the diamagnetic Meissner effect.

  20. The influence of society's mesoscopic structure on the rate of epidemic spreading

    NASA Astrophysics Data System (ADS)

    Kashisaz, Hadi; Darooneh, Amir H.

    2016-06-01

    In this study, we investigate the role of the mesoscopic structural properties of a scale-free social network on the contagion spreading. We focus on both the exponent of power-law community size distribution function (β) and the mixing parameter (μ). Findings show that increasing β reduces the rate of epidemic spreading. On the other hand, increasing μ increases the rate of epidemic spreading. Two innovating parameters, Temperature and cos θ , are introduced here to analyze these effects.

  1. Quantum fluctuations of mesoscopic RLC circuit with sources and time-dependant resistances

    NASA Astrophysics Data System (ADS)

    Neouioua, B.; Benamira, F.; Benbitour, M. A.

    2015-05-01

    We discuss the quantization of two mesoscopic coupled RLC circuits with sources and a time-dependent resistances. We use unitary transformations to decouple the system and calculate the charge-current fluctuations for each loop. An adequate time-dependent form of resistances is used to simplify the quantum evolution of the system. We find that the charge-current fluctuations verify the Heisenberg principle and decrease when the time elapses.

  2. The influence of society's mesoscopic structure on the rate of epidemic spreading.

    PubMed

    Kashisaz, Hadi; Darooneh, Amir H

    2016-06-01

    In this study, we investigate the role of the mesoscopic structural properties of a scale-free social network on the contagion spreading. We focus on both the exponent of power-law community size distribution function (β) and the mixing parameter (μ). Findings show that increasing β reduces the rate of epidemic spreading. On the other hand, increasing μ increases the rate of epidemic spreading. Two innovating parameters, Temperature and cos θ, are introduced here to analyze these effects. PMID:27368779

  3. Epistemological Predictors of "Self Efficacy on Learning Biology" and "Test Anxiety Related to Evaluation of Learning on Biology" for Pre-Service Elementary Teachers

    ERIC Educational Resources Information Center

    Koksal, Mustafa Serdar

    2011-01-01

    The degree to which pre-service teachers learn biology is related to both motivational factors of self-regulation and factors regarding epistemological beliefs. At the same time, self-regulation and epistemological beliefs are also associated with one another. Based on this relationship, the purpose of this study was to investigate the…

  4. A Comparison of the Hypothetical and Operational Objectives of the Nelson Biology Test, Form E 1965 and the New York State Regents Examination in Biology, June 1972.

    ERIC Educational Resources Information Center

    White, Mary Frances

    The investigator of this study, using a sample that included 382 boys from the City of New York, 366 girls from the City, and 379 boys and 368 girls from the suburban areas of the county of Westchester, attempted to ascertain the operational, cognitive objectives of the two biology achievement instruments. The method used to analyze objectives was…

  5. Stochastic path integrals and geometric theory of mesoscopic stochastic pumps and reversible ratchets.

    NASA Astrophysics Data System (ADS)

    Nemenman, Ilya

    2008-03-01

    A variety of stochastic systems, from enzyme kinetics to epidemiology, exhibit pump-like behaviors, where adiabatic changes of parameters result in a nonzero directed current through the system. Using the stochastic path integral technique from mesoscopic physics, we have been able to relate these and similar phenomena to geometric effects in mesoscopic stochastic kinetics and construct their unifying theory. In the talk, this methodology will be demonstrated on three examples: (1) an adiabatic pump effect in the evolution of a Michaelis-Menten enzyme, treated as a classical two-state stochastic system; (2) a reversible ratchet; and (3) a related novel phenomenon in a previously unexplored domain, namely the SIS epidemiological model. In all of these examples, pump-like currents follow from very similar geometric phase contributions to the effective action in the stochastic path integral representation of the moment generating functional, and our construction provides the universal technique for identification, prediction, and calculation of these currents in an arbitrary mesoscopic stochastic framework.

  6. Lattices of ultracold atom traps over arrays of nano- and mesoscopic superconducting disks

    NASA Astrophysics Data System (ADS)

    Sokolovsky, Vladimir; Prigozhin, Leonid

    2016-04-01

    A lattice of traps for ultracold neutral atoms is a promising tool for experimental investigation in quantum physics and quantum information processing. We consider regular arrays of thin film type-II superconducting nanodisks, with only one pinned vortex in each of them, and also arrays of mesoscopic disks, each containing many vortices whose distribution is characterized by the superconducting current density. In both cases we show theoretically that the induced magnetic field can create a 3D lattice of magnetic traps for cold atoms without any additional bias field. Applying a bias DC field parallel to the superconductor surface, one can control the depth and sizes of the traps, their heights above the chip surface, potential barriers between the traps, as well as the structure and dimension of the lattices. In the adiabatic approximation the atom cloud shape is represented by the shape of a closed iso-surface of the magnetic field magnitude chosen in accordance with the atom cloud temperature. The computed trap sizes, heights and the distances between the neighboring traps are typically from tens to hundreds nanometers for nanodisks and of the order of 1 μm for mesoscopic disks. Our calculations show that the depth of magnetic traps on mesoscopic disks is, typically, between 0.3 G and 7.6 G; for the nanodisks the depth is about 0.3 G.

  7. Analytical methods to determine the effective mesoscopic and macroscopic elastic properties of cortical bone.

    PubMed

    Parnell, William J; Vu, M B; Grimal, Q; Naili, S

    2012-07-01

    We compare theoretical predictions of the effective elastic moduli of cortical bone at both the meso- and macroscales. We consider the efficacy of three alternative approaches: the method of asymptotic homogenization, the Mori-Tanaka scheme and the Hashin-Rosen bounds. The methods concur for specific engineering moduli such as the axial Young's modulus but can vary for others. In a past study, the effect of porosity alone on mesoscopic properties of cortical bone was considered, taking the matrix to be isotropic. Here, we consider the additional influence of the transverse isotropy of the matrix. We make the point that micromechanical approaches can be used in two alternative ways to predict either the macroscopic (size of cortical bone sample) or mesoscopic (in between micro- and macroscales) effective moduli, depending upon the choice of representative volume element size. It is widely accepted that the mesoscale behaviour is an important aspect of the mechanical behaviour of bone but models incorporating its effect have started to appear only relatively recently. Before this only macroscopic behaviour was addressed. Comparisons are drawn with experimental data and simulations from the literature for macroscale predictions with particularly good agreement in the case of dry bone. Finally, we show how predictions of the effective mesoscopic elastic moduli can be made which retain dependence on the well-known porosity gradient across the thickness of cortical bone. PMID:22109098

  8. Mesoscopic Interactions and Species Coexistence in Evolutionary Game Dynamics of Cyclic Competitions

    NASA Astrophysics Data System (ADS)

    Cheng, Hongyan; Yao, Nan; Huang, Zi-Gang; Park, Junpyo; Do, Younghae; Lai, Ying-Cheng

    2014-12-01

    Evolutionary dynamical models for cyclic competitions of three species (e.g., rock, paper, and scissors, or RPS) provide a paradigm, at the microscopic level of individual interactions, to address many issues in coexistence and biodiversity. Real ecosystems often involve competitions among more than three species. By extending the RPS game model to five (rock-paper-scissors-lizard-Spock, or RPSLS) mobile species, we uncover a fundamental type of mesoscopic interactions among subgroups of species. In particular, competitions at the microscopic level lead to the emergence of various local groups in different regions of the space, each involving three species. It is the interactions among the groups that fundamentally determine how many species can coexist. In fact, as the mobility is increased from zero, two transitions can occur: one from a five- to a three-species coexistence state and another from the latter to a uniform, single-species state. We develop a mean-field theory to show that, in order to understand the first transition, group interactions at the mesoscopic scale must be taken into account. Our findings suggest, more broadly, the importance of mesoscopic interactions in coexistence of great many species.

  9. Combining molecular dynamics with mesoscopic Green’s function reaction dynamics simulations

    SciTech Connect

    Vijaykumar, Adithya; Bolhuis, Peter G.; Rein ten Wolde, Pieter

    2015-12-07

    In many reaction-diffusion processes, ranging from biochemical networks, catalysis, to complex self-assembly, the spatial distribution of the reactants and the stochastic character of their interactions are crucial for the macroscopic behavior. The recently developed mesoscopic Green’s Function Reaction Dynamics (GFRD) method enables efficient simulation at the particle level provided the microscopic dynamics can be integrated out. Yet, many processes exhibit non-trivial microscopic dynamics that can qualitatively change the macroscopic behavior, calling for an atomistic, microscopic description. We propose a novel approach that combines GFRD for simulating the system at the mesoscopic scale where particles are far apart, with a microscopic technique such as Langevin dynamics or Molecular Dynamics (MD), for simulating the system at the microscopic scale where reactants are in close proximity. This scheme defines the regions where the particles are close together and simulated with high microscopic resolution and those where they are far apart and simulated with lower mesoscopic resolution, adaptively on the fly. The new multi-scale scheme, called MD-GFRD, is generic and can be used to efficiently simulate reaction-diffusion systems at the particle level.

  10. Convergence of methods for coupling of microscopic and mesoscopic reaction-diffusion simulations

    NASA Astrophysics Data System (ADS)

    Flegg, Mark B.; Hellander, Stefan; Erban, Radek

    2015-05-01

    In this paper, three multiscale methods for coupling of mesoscopic (compartment-based) and microscopic (molecular-based) stochastic reaction-diffusion simulations are investigated. Two of the three methods that will be discussed in detail have been previously reported in the literature; the two-regime method (TRM) and the compartment-placement method (CPM). The third method that is introduced and analysed in this paper is called the ghost cell method (GCM), since it works by constructing a "ghost cell" in which molecules can disappear and jump into the compartment-based simulation. Presented is a comparison of sources of error. The convergent properties of this error are studied as the time step Δt (for updating the molecular-based part of the model) approaches zero. It is found that the error behaviour depends on another fundamental computational parameter h, the compartment size in the mesoscopic part of the model. Two important limiting cases, which appear in applications, are considered: Δt → 0 and h is fixed; Δt → 0 and h → 0 such that √{ Δt } / h is fixed. The error for previously developed approaches (the TRM and CPM) converges to zero only in the limiting case (ii), but not in case (i). It is shown that the error of the GCM converges in the limiting case (i). Thus the GCM is superior to previous coupling techniques if the mesoscopic description is much coarser than the microscopic part of the model.

  11. Mesoscopic Interactions and Species Coexistence in Evolutionary Game Dynamics of Cyclic Competitions

    PubMed Central

    Cheng, Hongyan; Yao, Nan; Huang, Zi-Gang; Park, Junpyo; Do, Younghae; Lai, Ying-Cheng

    2014-01-01

    Evolutionary dynamical models for cyclic competitions of three species (e.g., rock, paper, and scissors, or RPS) provide a paradigm, at the microscopic level of individual interactions, to address many issues in coexistence and biodiversity. Real ecosystems often involve competitions among more than three species. By extending the RPS game model to five (rock-paper-scissors-lizard-Spock, or RPSLS) mobile species, we uncover a fundamental type of mesoscopic interactions among subgroups of species. In particular, competitions at the microscopic level lead to the emergence of various local groups in different regions of the space, each involving three species. It is the interactions among the groups that fundamentally determine how many species can coexist. In fact, as the mobility is increased from zero, two transitions can occur: one from a five- to a three-species coexistence state and another from the latter to a uniform, single-species state. We develop a mean-field theory to show that, in order to understand the first transition, group interactions at the mesoscopic scale must be taken into account. Our findings suggest, more broadly, the importance of mesoscopic interactions in coexistence of great many species. PMID:25501627

  12. Thermal Design, Test and Analysis of PharmaSat, a Small Class D Spacecraft with a Biological Experiment

    NASA Technical Reports Server (NTRS)

    Diaz-Aguado, Millan F.; VanOutryve, Cassandra; Ghassemiah, Shakib; Beasley, Christopher; Schooley, Aaron

    2009-01-01

    Small spacecraft have been increasing in popularity because of their low cost, short turnaround and relative efficiency. In the past, small spacecraft have been primarily used for technology demonstrations, but advances in technology have made the miniaturization of space science possible [1,2]. PharmaSat is a low cost, small three cube size spacecraft, with a biological experiment on board, built at NASA (National Aeronautics and Space Administration) Ames Research Center. The thermal design of small spacecraft presents challenges as their smaller surface areas translate into power and thermal constraints. The spacecraft is thermally designed to run colder in the Low Earth Orbit space environment, and heated to reach the temperatures required by the science payload. The limited power supply obtained from the solar panels on small surfaces creates a constraint in the power used to heat the payload to required temperatures. The pressurized payload is isolated with low thermally conductance paths from the large ambient temperature changes. The thermal design consists of different optical properties of section surfaces, Multi Layer Insulation (MLI), low thermal conductance materials, flexible heaters and thermal spreaders. The payload temperature is controlled with temperature sensors and flexible heaters. Finite Element Analysis (FEA) and testing were used to aid the thermal design of the spacecraft. Various tests were conducted to verify the thermal design. An infrared imager was used on the electronic boards to find large heat sources and eliminate any possible temperature runaways. The spacecraft was tested in a thermal vacuum chamber to optimize the thermal and power analysis and qualify the thermal design of the spacecraft for the mission.

  13. Analysis of Eight Oil Spill Dispersants Using Rapid, In Vitro Tests for Endocrine and Other Biological Activity

    PubMed Central

    Judson, Richard S.; Martin, Matthew T.; Reif, David M.; Houck, Keith A.; Knudsen, Thomas B.; Rotroff, Daniel M.; Xia, Menghang; Sakamuru, Srilatha; Huang, Ruili; Shinn, Paul; Austin, Christopher P.; Kavlock, Robert J.; Dix, David J.

    2010-01-01

    The Deepwater Horizon oil spill has led to the use of >1 M gallons of oil spill dispersants, which are mixtures of surfactants and solvents. Because of this large scale use there is a critical need to understand the potential for toxicity of the currently used dispersant and potential alternatives, especially given the limited toxicity testing information that is available. In particular, some dispersants contain nonylphenol ethoxylates (NPEs), which can degrade to nonylphenol (NP), a known endocrine disruptor. Given the urgent need to generate toxicity data, we carried out a series of in vitro high-throughput assays on eight commercial dispersants. These assays focused on the estrogen and androgen receptors (ER and AR), but also included a larger battery of assays probing other biological pathways. Cytotoxicity in mammalian cells was also quantified. No activity was seen in any AR assay. Two dispersants showed a weak ER signal in one assay (EC50 of 16 ppm for Nokomis 3-F4 and 25 ppm for ZI-400). NPs and NPEs also had a weak signal in this same ER assay. Note that Corexit 9500, the currently used product, does not contain NPEs and did not show any ER activity. Cytotoxicity values for six of the dispersants were statistically indistinguishable, with median LC50 values ∼100 ppm. Two dispersants, JD 2000, SAF-RON GOLD, were significantly less cytotoxic than the others with LC50 values approaching or exceeding 1000 ppm. PMID:20602530

  14. Multifrequency acoustics as a probe of mesoscopic blood coagulation dynamics

    NASA Astrophysics Data System (ADS)

    Ganesan, Adarsh; Rajendran, Gokulnath; Ercole, Ari; Seshia, Ashwin

    2016-08-01

    Coagulation is a complex enzymatic polymerisation cascade. Disordered coagulation is common in medicine and may be life-threatening yet clinical assays are typically bulky and/or provide an incomplete picture of clot mechanical evolution. We present the adaptation of an in-plane acoustic wave device: quartz crystal microbalance with dissipation at multiple harmonics to determine the time-evolution of mesoscale mechanical properties of clot formation in vitro. This approach is sensitive to changes in surface and bulk clot structure in various models of induced coagulopathy. Furthermore, we are able to show that clot formation at surfaces has different kinetics and mechanical strength to that in the bulk, which may have implications for the design of bioprosthetic materials. The "Multifrequency acoustics" approach thus enables unique capability to portray biological processes concerning blood coagulation.

  15. Imaging mesoscopic nuclear spin noise with a diamond magnetometer

    NASA Astrophysics Data System (ADS)

    Meriles, Carlos A.; Jiang, Liang; Goldstein, Garry; Hodges, Jonathan S.; Maze, Jeronimo; Lukin, Mikhail D.; Cappellaro, Paola

    2010-09-01

    Magnetic resonance imaging can characterize and discriminate among tissues using their diverse physical and biochemical properties. Unfortunately, submicrometer screening of biological specimens is presently not possible, mainly due to lack of detection sensitivity. Here we analyze the use of a nitrogen-vacancy center in diamond as a magnetic sensor for nanoscale nuclear spin imaging and spectroscopy. We examine the ability of such a sensor to probe the fluctuations of the "classical" dipolar field due to a large number of neighboring nuclear spins in a densely protonated sample. We identify detection protocols that appropriately take into account the quantum character of the sensor and find a signal-to-noise ratio compatible with realistic experimental parameters. Through various example calculations we illustrate different kinds of image contrast. In particular, we show how to exploit the comparatively long nuclear spin correlation times to reconstruct a local, high-resolution sample spectrum.

  16. Physics Characterization of TLD-600 and TLD-700 and Acceptance Testing of New XRAD 160 Biological X-Ray Irradiator

    NASA Astrophysics Data System (ADS)

    Cao, Yanan

    2: Acceptance testing of new X-RAD 160 Biological X-Ray Irradiator. Purpose: An X-RAD 160 Biological X-Ray Irradiator was recently installed at Duke University to serve as a key device for cellular radiobiology research. The purpose of this study is to perform acceptance testing on the new irradiator for operator radiation safety and irradiation specifications. Methods: The acceptance testing included tests of the following components: (1) Leakage radiation survey, (2) Half-value layer (beam quality), (3) Uniformity, (4) KVp accuracy, (5) Exposure at varying mA (linearity of mA), (6) Exposure at varying kVp, (7) Inverse square measurements, (8) Field size measurement, (9) Exposure constancy. The irradiation parameters for each components of first round of acceptance testing performed on September 21, 2012 were: Leakage radiation survey (none, 160 kVp, 18 mA, 200s), Beam quality (40cm, 50-140 kVp in 10 kVp incensement, 1 mA, 10s, none), Uniformity (40cm, 160 kVp, 18 mA, 15s, F1), KVp accuracy (40cm, 50-150 kVp in 10 kVp incensement, 10 mA, 15s, none), Linearity of mA (40cm, 160 kVp, 2-18 mA, 15s, none), Inverse square measurements (20-63cm, 160 kVp, 1mA, 30s, none), Field size measurement (40cm, 160 kVp, 10 mA, 15s, none), Exposure constancy (40cm, 160 kVp, 18 mA, 20s, none). The irradiation parameters for each components for each components of second round of acceptance testing performed on November 18, 2012 were: Beam quality (40cm, 35-150 kVp, 1 mA, 10s, F1), KVp accuracy (40cm, 35-150 kVp, 1 mA, 10s, F1), Variation of kVp (40cm, 160 kVp, 18 mA, 30s, F1), Linearity of mA (40cm, 160 kVp, 1-18 mA, 30s, F1), Uniformity (40cm, 160 kVp, 18 mA, 30s, F1), Inverse square measurements (20-63cm, 160 kVp, 18 mA, 30s, F1). Results: The first round of acceptance testing performed on September 21, 2012 failed due to the fact that the measured exposure along the X-axis was significantly non-uniform; the exposure greatly decreases going in the left direction, which is a clear

  17. Factors in seventh grade academics associated with performance levels on the tenth grade biology end of course test in selected middle and high schools in northwest Georgia

    NASA Astrophysics Data System (ADS)

    Ward, Jennifer Henry

    This study attempted to identify factors in seventh grade academics that are associated with overall success in tenth grade biology. The study addressed the following research questions: Are there significant differences in performance levels in seventh grade Criterion Referenced Competency Test (CRCT) scores in science, math, reading, and language arts associated with performance categories in tenth grade biology End of Course Test (EOCT) and the following demographic variables : gender, ethnicity, socioeconomic status, disability category, and English language proficiency level? Is there a relationship among the categorical variables on the tenth grade biology EOCT and the same five demographic variables? Retrospective causal comparative research was used on a representative sample from the middle schools in three North Georgia counties who took the four CRCTs in the 2006-2007 school year, and took the biology EOCT in the 2009-2010 school year. Chi square was used to determine the relationships of the various demographic variables on three biology EOCT performance categories. Twoway ANOVA determined relationships between the seventh grade CRCT scores of students in the various demographic groups and their performance levels on the biology EOCT. Students' performance levels on the biology EOCT matched their performance levels on the seventh grade CRCTs consistently. Females performed better than males on all seventh grade CRCTs. Black and Hispanic students did worse than White and Asian/Asian Indian students on the math CRCT. Students living in poverty did worse on reading and language arts CRCTs than students who were better off. Special education students did worse on science, reading, and language arts CRCTs than students not receiving special education services. English language learners did worse than native English speakers on all seventh grade CRCTs. These findings suggest that remedial measures may be taken in the seventh grade that could impact

  18. A mesostructurally-based anisotropic continuum model for biological soft tissues--decoupled invariant formulation.

    PubMed

    Limbert, Georges

    2011-11-01

    Characterising and modelling the mechanical behaviour of biological soft tissues is an essential step in the development of predictive computational models to assist research for a wide range of applications in medicine, biology, tissue engineering, pharmaceutics, consumer goods, cosmetics, transport or military. It is therefore critical to develop constitutive models that can capture particular rheological mechanisms operating at specific length scales so that these models are adapted for their intended applications. Here, a novel mesoscopically-based decoupled invariant-based continuum constitutive framework for transversely isotropic and orthotropic biological soft tissues is developed. A notable feature of the formulation is the full decoupling of shear interactions. The constitutive model is based on a combination of the framework proposed by Lu and Zhang [Lu, J., Zhang, L., 2005. Physically motivated invariant formulation for transversely isotropic hyperelasticity. International Journal of Solids and Structures 42, 6015-6031] and the entropic mechanics of tropocollagen molecules and collagen assemblies. One of the key aspects of the formulation is to use physically-based nanoscopic quantities that could be extracted from experiments and/or atomistic/molecular dynamics simulations to inform the macroscopic constitutive behaviour. This effectively couples the material properties at different levels of the multi-scale hierarchical structure of collagenous tissues. The orthotropic hyperelastic model was shown to reproduce very well the experimental multi-axial properties of rabbit skin. A new insight into the shear response of a skin sample subjected to a simulated indentation test was obtained using numerical direct sensitivity analyses. PMID:22098866

  19. Assessing Students' Abilities in Processes of Scientific Inquiry in Biology Using a Paper-and-Pencil Test

    ERIC Educational Resources Information Center

    Nowak, Kathrin Helena; Nehring, Andreas; Tiemann, Rüdiger; Upmeier zu Belzen, Annette

    2013-01-01

    The aim of the study was to describe, categorise and analyse students' (aged 14-16) processes of scientific inquiry in biology and chemistry education. Therefore, a theoretical structure for scientific inquiry for both biology and chemistry, the VerE model, was developed. This model consists of nine epistemological acts, which combine…

  20. Open-field host specificity test of Gratiana boliviana (Coleoptera:Chrysomelidae), a biological control agent of Tropical Soda Apple (Solanaceae) in the United States

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An open-field experiment was conducted to asses the suitability of the South American leaf feeding beetle Gratiana boliviana Spaeth for biological control of Solanum viarum Dunal in the USA. An open-field test with eggplant, Solanum melongena L., was conducted on the campus of the University of Buen...

  1. Biological testing and chemical analysis of process materials from an integrated two stage coal liquefaction: a status report

    SciTech Connect

    Wilson, B.W.; Buhl, P.; Moroni, E.C.

    1983-07-01

    Samples for chemical characterization and biological testing were obtained from ITSL runs 3LCF7, 3LCF8 and 3LCF9. Chemical analysis of these materials showed that SCT products were composed of fewer compounds than analogous materials from Solvent Refined Coal (SRC) processes. Major components in the SCT materials were three-, four-, five- and six-ring neutral polycyclic aromatic hydrocarbons (PAH). Methyl(C/sub 1/) and C/sub 2/ homologs of these compounds were present in relatively low concentrations, compared to their non-alkylated homologs. Organic nitrogen was primarily in the form of tertiary polycyclic aromatic nitrogen heterocycles and carbazoles. Little or no amino PAH (APAH) or cyano PAH were detected in samples taken during normal PDU operations, however, mutagenic APAH were produced during off-normal operation. Microbial mutagenicity appeared to be due mainly to the presence of APAH which were probably formed in the LC finer due to failure of the catalyst to promote deamination following carbon-nitrogen bond scission of nitrogen-containing hydroaromatics. This failure was observed for the off-normal runs where it was likely that the catalyst had been deactivated. Carcinogenic activity of ITSL materials as assessed by (tumors per animal) in the initiation/promotion mouse skin painting assay was slightly reduced for materials produced with good catalyst under normal operation compared to those collected during recycle of the LC Finer feed. Initiation activity of the latter samples did not appear to be significantly different from that of other coal derived materials with comparable boiling ranges. The observed initiation activity was not unexpected, considering analytical data which showed the presence of four-, five- and six-ring PAH in ITSL materials.

  2. Critical behavior of a two-dimensional complex fluid: Macroscopic and mesoscopic views

    NASA Astrophysics Data System (ADS)

    Choudhuri, Madhumita; Datta, Alokmay

    2016-04-01

    Liquid disordered (Ld) to liquid ordered (Lo) phase transition in myristic acid [MyA, CH3(CH2) 12COOH ] Langmuir monolayers was studied macroscopically as well as mesoscopically to locate the critical point. Macroscopically, isotherms of the monolayer were obtained across the 20 ∘C-38 ∘Ctemperature (T ) range and the critical point was estimated, primarily from the vanishing of the order parameter, at ≈38 ∘C. Mesoscopically, domain morphology in the Ld-Lo coexistence regime was imaged using the technique of Brewster angle microscopy (BAM) as a function of T and the corresponding power spectral density function (PSDF) obtained. Monolayer morphology passed from stable circular domains and a sharp peak in PSDF to stable dendritic domains and a divergence of the correlation length as the critical point was approached from below. The critical point was found to be consistent at ≈38 ∘Cfrom both isotherm and BAM results. In the critical regime the scaling behavior of the transition followed the two-dimensional Ising model. Additionally, we obtained a precritical regime, over a temperature range of ≈8 ∘C below Tc, characterized by fluctuations in the order parameter at the macroscopic scale and at the mesoscopic scale characterized by unstable domains of fingering or dendritic morphology as well as proliferation of a large number of small sized domains, multiple peaks in the power spectra, and a corresponding fluctuation in the peak q values with T . Further, while comparing temperature studies on an ensemble of MyA monolayers with those on a single monolayer, the system was found to be not strictly ergodic in that the ensemble development did not strictly match with the time development in the system. In particular, the critical temperature was found to be lowered in the latter. These results clearly show that the critical behavior in fatty acid monolayer phase transitions have features of both complex and nonequilibrium systems.

  3. Convergence of methods for coupling of microscopic and mesoscopic reaction-diffusion simulations

    PubMed Central

    Flegga, Mark B.; Hellander, Stefan; Erban, Radek

    2015-01-01

    In this paper, three multiscale methods for coupling of mesoscopic (compartment-based) and microscopic (molecular-based) stochastic reaction-diffusion simulations are investigated. Two of the three methods that will be discussed in detail have been previously reported in the literature; the two-regime method (TRM) and the compartment-placement method (CPM). The third method that is introduced and analysed in this paper is called the ghost cell method (GCM), since it works by constructing a “ghost cell” in which molecules can disappear and jump into the compartment-based simulation. Presented is a comparison of sources of error. The convergent properties of this error are studied as the time step Δt (for updating the molecular-based part of the model) approaches zero. It is found that the error behaviour depends on another fundamental computational parameter h, the compartment size in the mesoscopic part of the model. Two important limiting cases, which appear in applications, are considered: (i) Δt → 0 and h is fixed; (ii) Δt → 0 and h → 0 such that √Δt/h is fixed. The error for previously developed approaches (the TRM and CPM) converges to zero only in the limiting case (ii), but not in case (i). It is shown that the error of the GCM converges in the limiting case (i). Thus the GCM is superior to previous coupling techniques if the mesoscopic description is much coarser than the microscopic part of the model. PMID:26568640

  4. Towards a mesoscopic model of water-like fluids with hydrodynamic interactions.

    PubMed

    Mazzitelli, Irene; Venturoli, Maddalena; Melchionna, Simone; Succi, Sauro

    2011-09-28

    We present a mesoscopic lattice model for non-ideal fluid flows with directional interactions, mimicking the effects of hydrogen bonds in water. The model supports a rich and complex structural dynamics of the orientational order parameter, and exhibits the formation of disordered domains whose size and shape depend on the relative strength of directional order and thermal diffusivity. By letting the directional forces carry an inverse density dependence, the model is able to display a correlation between ordered domains and low density regions, reflecting the idea of water as a denser liquid in the disordered state than in the ordered one. PMID:21974559

  5. Mesoscopic strain fields in woven composites: Experiments vs. finite element modeling

    NASA Astrophysics Data System (ADS)

    Nicoletto, Gianni; Anzelotti, Giancarlo; Riva, Enrica

    2009-03-01

    Detailed determination of strain in woven composite materials is fundamental for understanding their mechanics and for validating sophisticated computational models. The digital image correlation technique is briefly presented and applied to the full-field strain determination in a twill-weave carbon-fiber-reinforced-plastic (CFRP) composite under in-plane loading. The experimental results are used to assess companion results obtained with an ad hoc finite element-based model. The DIC vs. FEM comparison is carried out at the mesoscopic scale.

  6. Quantum Fluctuations of Mesoscopic Damped Circuit Involving Capacitance-Inductance Coupling at a Finite Temperature

    NASA Astrophysics Data System (ADS)

    Xu, Xing-Lei; Xu, Shi-Min; Li, Hong-Qi

    2008-06-01

    The quantization of mesoscopic damped circuit involving capacitance-inductance coupling is proposed by the method of thrice linear transformation and damped harmonic oscillator quantization. The quantum fluctuations of the charges and current of each loop are calculated by thermo-field dynamics (TFD) in thermal vacuum state, thermal coherent state and thermal squeezed state, respectively. It is shown that the quantum fluctuations of the charges and current not only depend on circuit inherent parameter and coupled magnitude, but also rely on squeezed coefficients, squeezed angle, environmental temperature and damped resistance. And, because of influence of environmental temperature and damped resistance, the quantum fluctuations increase with increasing temperature and decrease with prolonging time.

  7. Quantum fluctuations of mesoscopic RLC circuit involving complicated coupling in thermal squeezed state

    NASA Astrophysics Data System (ADS)

    Xu, Xing-Lei; Li, Hong-Qi; Wang, Ji-Suo

    2007-06-01

    Starting from the Kirchhoff's equation for electric circuits and in reference of damped harmonic oscillator quantization and thermo-field dynamics (TFD), the quantization of damped double-resonance mesoscopic RLC circuit involving complicated coupling is proposed. The quantum fluctuations of charge and current of each loop are calculated in thermal squeezed state, thermal coherent state and thermal vacuum state, respectively. The results not only depend on the circuit proper parameters and coupled magnitude, but also rely on the squeezing coefficients, environmental temperature and damped resistance. The fluctuations increase with temperature rising and decay with time.

  8. Collective state measurement of mesoscopic ensembles with single-atom resolution.

    PubMed

    Zhang, Hao; McConnell, Robert; Cuk, Senka; Lin, Qian; Schleier-Smith, Monika H; Leroux, Ian D; Vuletić, Vladan

    2012-09-28

    We demonstrate single-atom resolution, as well as detection sensitivity more than 20 dB below the quantum projection noise limit, for hyperfine-state-selective measurements on mesoscopic ensembles containing 100 or more atoms. The measurement detects the atom-induced shift of the resonance frequency of an optical cavity containing the ensemble. While spatially varying coupling of atoms to the cavity prevents the direct observation of a quantized signal, the demonstrated measurement resolution provides the readout capability necessary for atomic interferometry substantially below the standard quantum limit and down to the Heisenberg limit. PMID:23030090

  9. Bridging the Gap between Mesoscopic and Macroscopic Models: The Case of Multicellular Tumor Spheroids

    NASA Astrophysics Data System (ADS)

    Delsanto, P. P.; Griffa, M.; Condat, C. A.; Delsanto, S.; Morra, L.

    2005-04-01

    Multicellular tumor spheroids are valuable experimental tools in cancer research. By introducing an intermediate model, we have been able to successfully relate mesoscopic and macroscopic descriptions of spheroid growth. Since these descriptions stem from completely different roots (cell dynamics, and energy conservation and scaling arguments, respectively), their consistency validates both approaches and allows us to establish a direct correspondence between parameters characterizing processes occurring at different scales. Our approach may find applications as an example of bridging the gap between models at different scale levels in other contexts.

  10. Mesoscopic Correlation of Supramolecular Chirality in One-Dimensional Hydrogen-Bonded Assemblies

    SciTech Connect

    Weckesser, J.; De Vita, A.; Barth, J. V.; Cai, C.; Kern, K.

    2001-08-27

    The ordering of 4-[trans-2-(pyrid-4-yl-vinyl)] benzoic acid, a two-dimensional chiral species, was studied by scanning tunneling microscopy at noble metal surfaces. Homochiral molecules self-assemble in supramolecular chiral hydrogen-bonded twin chains, which order in nanogratings where the supramolecular chirality is strictly correlated over the entire {mu}m domains without intimate molecular contact. Model simulations indicate that the underlying mesoscopic chiral resolution is associated with twin chains acting as chiroselective templates for transient molecular attachment, which process mediates the gratings' evolution.

  11. On the dynamics of a time-dependent mesoscopic LC circuit with a negative inductance

    NASA Astrophysics Data System (ADS)

    Pedrosa, I. A.; Nogueira, E.; Guedes, I.

    2016-05-01

    We discuss the problem of a mesoscopic LC circuit with a negative inductance ruled by a time-dependent Hermitian Hamiltonian. Classically, we find unusual expressions for the Faraday’s law and for the inductance of a solenoid. Quantum mechanically, we solve exactly the time-dependent Schrödinger equation through the Lewis and Riesenfeld invariant operator method and construct Gaussian wave packet solutions for this time-dependent LC circuit. We also evaluate the expectation values of the charge and the magnetic flux in these Gaussian states, their quantum fluctuations and the corresponding uncertainty product.

  12. Mesoscopic modeling of multi-physicochemical transport phenomena in porous media

    SciTech Connect

    Kang, Qinjin; Wang, Moran; Mukherjee, Partha P; Lichtner, Peter C

    2009-01-01

    We present our recent progress on mesoscopic modeling of multi-physicochemical transport phenomena in porous media based on the lattice Boltzmann method. Simulation examples include injection of CO{sub 2} saturated brine into a limestone rock, two-phase behavior and flooding phenomena in polymer electrolyte fuel cells, and electroosmosis in homogeneously charged porous media. It is shown that the lattice Boltzmann method can account for multiple, coupled physicochemical processes in these systems and can shed some light on the underlying physics occuning at the fundamental scale. Therefore, it can be a potential powerful numerical tool to analyze multi-physicochemical processes in various energy, earth, and environmental systems.

  13. Paramagnetic supercurrent and transition points between different vortex states in mesoscopic superconducting disks

    NASA Astrophysics Data System (ADS)

    Kanda, Akinobu; Ootuka, Youiti

    2004-05-01

    We investigated the paramagnetic supercurrent and the transition points between different vortex states in mesoscopic superconducting disks. We observed paramagnetic supercurrent in four disks: two 33 nm thick and two 50 nm thick, all 1.50 μm in diameter. Analyses of the supercurrent symmetry and the intervals between transition points showed that defects did not play a crucial role in our samples or in the samples first reported to show the paramagnetic Meissner effect (PME) [Nature 396 (1998) 144]. This supports our previous conclusion that the origin of the PME is the paramagnetic supercurrent.

  14. A single Abrikosov vortex trapped in a mesoscopic superconducting cylindrical surface

    NASA Astrophysics Data System (ADS)

    Carapella, G.; Sabatino, P.; Costabile, G.

    2011-11-01

    We investigate the behaviour of a single Abrikosov vortex trapped in a mesoscopic superconducting cylindrical surface with a magnetic field applied transverse to its axis. In the framework of the time-dependent Ginzburg-Landau formalism we show that, provided the transport current and the magnetic field are not large, the vortex behaves as an overdamped quasi-particle in a tilted washboard potential. The cylindrical thin strip with the trapped vortex exhibits E(J) curves and time-dependent electric fields very similar to the ones exhibited by a resistively shunted Josephson weak link.

  15. Charged, dipolar soft matter systems from a combined microscopic–mesoscopic viewpoint

    NASA Astrophysics Data System (ADS)

    Schröder, Christian; Steinhauser, Othmar

    2016-09-01

    As an example of charged, dipolar soft matter, the ionic liquid 1-ethyl-3-methyl-imidazolium dicyanamide is studied by coarse-grained molecular dynamics simulations. We focus on the link between microscopic and mesoscopic properties for both structure and dynamics. Thereby, the generalized Kirkwood g K-factor plays a central role in establishing this link which is not possible on the basis of molecular hydrodynamics. The decoupling between translational and rotational motion is indicative of the dynamical heterogeneity in ionic liquids.

  16. Linear invariants and the quantum dynamics of a nonstationary mesoscopic RLC circuit with a source

    NASA Astrophysics Data System (ADS)

    Pedrosa, I. A.; Melo, J. L.; Nogueira, E.

    2014-10-01

    In this paper, we use Hermitian linear invariants and the Lewis and Riesenfeld invariant method to obtain the general solution of the Schrödinger equation for a mesoscopic RLC circuit with time-dependent resistance, inductance, capacitance and a power source and represent it in terms of an arbitrary weight function. In addition, we construct Gaussian wave packet solutions for this electromagnetic oscillation circuit and employ them to calculate the quantum fluctuations of the charge and the magnetic flux as well as the associated uncertainty product. We also show that the width of the Gaussian packet and the fluctuations do not depend on the external power.

  17. Sub-Poissonian atom-number fluctuations by three-body loss in mesoscopic ensembles.

    PubMed

    Whitlock, S; Ockeloen, C F; Spreeuw, R J C

    2010-03-26

    We show that three-body loss of trapped atoms leads to sub-Poissonian atom-number fluctuations. We prepare hundreds of dense ultracold ensembles in an array of magnetic microtraps which undergo rapid three-body decay. The shot-to-shot fluctuations of the number of atoms per trap are sub-Poissonian, for ensembles comprising 50-300 atoms. The measured relative variance or Fano factor F=0.53+/-0.22 agrees very well with the prediction by an analytic theory (F=3/5) and numerical calculations. These results will facilitate studies of quantum information science with mesoscopic ensembles. PMID:20366518

  18. Direct Observation of Vortex Shells and Magic Numbers in Mesoscopic Superconducting Disks

    NASA Astrophysics Data System (ADS)

    Grigorieva, I. V.; Escoffier, W.; Richardson, J.; Vinnikov, L. Y.; Dubonos, S.; Oboznov, V.

    2006-02-01

    We have studied vortex configurations in mesoscopic superconducting disks using the Bitter decoration technique. For a broad range of vorticities L the circular geometry is found to lead to the formation of concentric shells of vortices. From images obtained on disks of different sizes in a range of magnetic fields we traced the evolution of vortex states and identified stable and metastable configurations of interacting vortices. Furthermore, the analysis of shell filling with increasing L allowed us to identify magic numbers corresponding to the appearance of consecutive new shells.

  19. Twisting Carbon Nanotube Ropes with the Mesoscopic Distinct Element Method: Geometry, Packing, and Nanomechanics.

    PubMed

    Wang, Yuezhou; Ostanin, Igor; Gaidău, Cristian; Dumitric, Traian

    2015-11-17

    The geometry and internal packing of twisted ropes composed of carbon nanotubes (CNTs) are considered, and a numerical solution in the context of the mesoscopic distinct element method (MDEM) is proposed. Compared to the state of the art, MDEM accounts in a computationally tractable manner for both the deformation of the fiber and the distributed van der Waals cohesive energy between fibers. These features enable us to investigate the torsional response in a new regime where the twisted rope develops packing rearrangements and aspect-ratio-dependent geometric nonlinearities. MDEM emerges as a robust simulation method for studying twisted agglomerates comprising semiflexible nanofibers. PMID:26411396

  20. Charged, dipolar soft matter systems from a combined microscopic-mesoscopic viewpoint.

    PubMed

    Schröder, Christian; Steinhauser, Othmar

    2016-09-01

    As an example of charged, dipolar soft matter, the ionic liquid 1-ethyl-3-methyl-imidazolium dicyanamide is studied by coarse-grained molecular dynamics simulations. We focus on the link between microscopic and mesoscopic properties for both structure and dynamics. Thereby, the generalized Kirkwood g K-factor plays a central role in establishing this link which is not possible on the basis of molecular hydrodynamics. The decoupling between translational and rotational motion is indicative of the dynamical heterogeneity in ionic liquids. PMID:27376788

  1. Structure and rheology of star polymers in confined geometries: a mesoscopic simulation study.

    PubMed

    Zheng, Feiwo; Goujon, Florent; Mendonça, Ana C F; Malfreyt, Patrice; Tildesley, Dominic J

    2015-11-28

    Mesoscopic simulations of star polymer melts adsorbed onto solid surfaces are performed using the dissipative particle dynamics (DPD) method. A set of parameters is developed to study the low functionality star polymers under shear. The use of a new bond-angle potential between the arms of the star creates more rigid chains and discriminates between different functionalities at equilibrium, but still allows the polymers to deform appropriately under shear. The rheology of the polymer melts is studied by calculating the kinetic friction and viscosity and there is good agreement with experimental properties of these systems. The study is completed with predictive simulations of star polymer solutions in an athermal solvent. PMID:26435466

  2. Mesoscopic structural analysis of bedrock exposures at the Oak Ridge K-25 Site, Oak Ridge, Tennessee

    SciTech Connect

    Lemiszki, P.J.

    1995-07-01

    This document presents the detailed study of outcrop of mesoscopic structures during the geologic mapping completed in 1992-1993. The purpose of this study was to document the geometry and style of outcrop scale structures, such as fractures and faults and relate them to map scale structures present in the Oak Ridge K-25 Area. This report was prepared to document site characterization data collected during the scoping phase investigations in accordance with the requirements of the Comprehensive Environmental Response, Compensation, and Liability Act.

  3. Photo-induced conductance fluctuations in mesoscopic Ge/Si systems with quantum dots

    SciTech Connect

    Stepina, N. P.; Dvurechenskii, A. V.; Nikiforov, A. I.; Moers, J.; Gruetzmacher, D.

    2014-08-20

    We study the evolution of electron transport in strongly localized mesoscopic system with quantum dots under small photon flux. Exploring devices with narrow transport channels lead to the observation of giant fluctuations of the photoconductance, which is attributed to the strong dependence of hopping current on the filling of dots by holes. In our experiments, single-photon mode operation is indicated by the linear dependence of the frequency of photo-induced fluctuations on the light intensity and the step-like response of conductance on the pulse excitation. The effect of the light wavelength, measurement temperature, size of the conductive channel on the device efficiency are considered.

  4. Statistical model of dephasing in mesoscopic devices introduced in the scattering matrix formalism

    NASA Astrophysics Data System (ADS)

    Pala, Marco G.; Iannaccone, Giuseppe

    2004-06-01

    We propose a phenomenological model of dephasing in mesoscopic transport, based on the introduction of random-phase fluctuations in the computation of the scattering matrix of the system. A Monte Carlo averaging procedure allows us to extract electrical and microscopic device properties. We show that, in this picture, scattering matrix properties enforced by current conservation and time-reversal invariance still hold. In order to assess the validity of the proposed approach, we present simulations of conductance and magnetoconductance of Aharonov-Bohm rings that reproduce the behavior observed in experiments, in particular as far as aspects related to decoherence are concerned.

  5. USE OF THE BLUE MUSSEL, MYTILUS EDULIS, IN WATER QUALITY TOXICITY TESTING AND IN SITU MARINE BIOLOGICAL MONITORING

    EPA Science Inventory

    An effort was undertaken at the Environmental Protection Agency's (EPA) Environmental Research Laboratory, Narragansett (ERL-N),Rhode Island, to evaluate the integration of in situ biological monitoring with the blue mussel, Mytilus edulis L. into EPA's Complex Effluent Toxicity ...

  6. Development and application of a two-tier diagnostic test measuring college biology students' understanding of diffusion and osmosis after a course of instruction

    NASA Astrophysics Data System (ADS)

    Odom, Arthur Louis; Barrow, Lloyd H.

    This study involved the development and application of a two-tier diagnostic test measuring college biology students' understanding of diffusion and osmosis after a course of instruction. The development procedure had three general steps: defining the content boundaries of the test, collecting information on students' misconceptions, and instrument development. Misconception data were collected from interviews and multiple-choice questions with free response answers. The data were used to develop 12 two-tier multiple choice items in which the first tier examined content knowledge and the second examined understanding of that knowledge. The conceptual knowledge examined was the particulate and random nature of matter, concentration and tonicity, the influence of life forces on diffusion and osmosis, membranes, kinetic energy of matter, the process of diffusion, and the process of osmosis. The diagnostic instrument was administered to 240 students (123 non-biology majors and 117 biology majors) enrolled in a college freshman biology laboratory course. The students had completed a unit on diffusion and osmosis. The content taught was carefully defined by propositional knowledge statements, and was the same content that defined the content boundaries of the test. The split-half reliability was .74. Difficulty indices ranged from 0.23 to 0.95, and discrimination indices ranged from 0.21 to 0.65. Each item was analyzed to determine student understanding of, and identify misconceptions about, diffusion and osmosis.Received: 18 June 1993; Revised: 16 February 1994;

  7. Analysis of the properties of the molecular-cluster xenon mixture in the mesoscopic phase transition region

    NASA Astrophysics Data System (ADS)

    Kurlapov, L. I.; Kassymov, A. B.

    2016-04-01

    We report on the results of calculation of the concentrations of cluster subcomponents in a molecular-cluster xenon mixture at temperatures and pressures at which the gas experiences a mesoscopic phase transition. The existence of such a transition follows from singularities of the temperature dependence of viscosity, from the behavior of the cluster thermodiffusion coefficient, and from the features of the distributions of cluster subcomponents in the centrifuge. The mesoscopic phase transition is manifested in the intermediate position of the molecular-cluster mixture between the gas and the liquid judging from its properties in the transition region.

  8. A new transport phenomenon in nanostructures: a mesoscopic analog of the Braess paradox encountered in road networks

    NASA Astrophysics Data System (ADS)

    Pala, Marco; Sellier, Hermann; Hackens, Benoit; Martins, Frederico; Bayot, Vincent; Huant, Serge

    2012-08-01

    The Braess paradox, known for traffic and other classical networks, lies in the fact that adding a new route to a congested network in an attempt to relieve congestion can degrade counterintuitively the overall network performance. Recently, we have extended the concept of the Braess paradox to semiconductor mesoscopic networks, whose transport properties are governed by quantum physics. In this paper, we demonstrate theoretically that, alike in classical systems, congestion plays a key role in the occurrence of a Braess paradox in mesoscopic networks.

  9. Current status and recommendations for the future of research, teaching, and testing in the biological sciences of radiation oncology: report of the American Society for Radiation Oncology Cancer Biology/Radiation Biology Task Force, executive summary.

    PubMed

    Wallner, Paul E; Anscher, Mitchell S; Barker, Christopher A; Bassetti, Michael; Bristow, Robert G; Cha, Yong I; Dicker, Adam P; Formenti, Silvia C; Graves, Edward E; Hahn, Stephen M; Hei, Tom K; Kimmelman, Alec C; Kirsch, David G; Kozak, Kevin R; Lawrence, Theodore S; Marples, Brian; McBride, William H; Mikkelsen, Ross B; Park, Catherine C; Weidhaas, Joanne B; Zietman, Anthony L; Steinberg, Michael

    2014-01-01

    In early 2011, a dialogue was initiated within the Board of Directors (BOD) of the American Society for Radiation Oncology (ASTRO) regarding the future of the basic sciences of the specialty, primarily focused on the current state and potential future direction of basic research within radiation oncology. After consideration of the complexity of the issues involved and the precise nature of the undertaking, in August 2011, the BOD empanelled a Cancer Biology/Radiation Biology Task Force (TF). The TF was charged with developing an accurate snapshot of the current state of basic (preclinical) research in radiation oncology from the perspective of relevance to the modern clinical practice of radiation oncology as well as the education of our trainees and attending physicians in the biological sciences. The TF was further charged with making suggestions as to critical areas of biological basic research investigation that might be most likely to maintain and build further the scientific foundation and vitality of radiation oncology as an independent and vibrant medical specialty. It was not within the scope of service of the TF to consider the quality of ongoing research efforts within the broader radiation oncology space, to presume to consider their future potential, or to discourage in any way the investigators committed to areas of interest other than those targeted. The TF charge specifically precluded consideration of research issues related to technology, physics, or clinical investigations. This document represents an Executive Summary of the Task Force report. PMID:24246724

  10. Current Status and Recommendations for the Future of Research, Teaching, and Testing in the Biological Sciences of Radiation Oncology: Report of the American Society for Radiation Oncology Cancer Biology/Radiation Biology Task Force, Executive Summary

    SciTech Connect

    Wallner, Paul E.; Anscher, Mitchell S.; Barker, Christopher A.; Bassetti, Michael; Bristow, Robert G.; Dicker, Adam P.; Formenti, Silvia C.; Graves, Edward E.; Hahn, Stephen M.; Hei, Tom K.; Kimmelman, Alec C.; Kirsch, David G.; Kozak, Kevin R.; Lawrence, Theodore S.; Marples, Brian; and others

    2014-01-01

    In early 2011, a dialogue was initiated within the Board of Directors (BOD) of the American Society for Radiation Oncology (ASTRO) regarding the future of the basic sciences of the specialty, primarily focused on the current state and potential future direction of basic research within radiation oncology. After consideration of the complexity of the issues involved and the precise nature of the undertaking, in August 2011, the BOD empanelled a Cancer Biology/Radiation Biology Task Force (TF). The TF was charged with developing an accurate snapshot of the current state of basic (preclinical) research in radiation oncology from the perspective of relevance to the modern clinical practice of radiation oncology as well as the education of our trainees and attending physicians in the biological sciences. The TF was further charged with making suggestions as to critical areas of biological basic research investigation that might be most likely to maintain and build further the scientific foundation and vitality of radiation oncology as an independent and vibrant medical specialty. It was not within the scope of service of the TF to consider the quality of ongoing research efforts within the broader radiation oncology space, to presume to consider their future potential, or to discourage in any way the investigators committed to areas of interest other than those targeted. The TF charge specifically precluded consideration of research issues related to technology, physics, or clinical investigations. This document represents an Executive Summary of the Task Force report.

  11. Universality and quantized response in bosonic mesoscopic tunneling

    NASA Astrophysics Data System (ADS)

    Yin, Shaoyu; Béri, Benjamin

    2016-06-01

    We show that tunneling involving bosonic wires and/or boson integer quantum Hall (bIQH) edges is characterized by features that are far more universal than those in their fermionic counterpart. Considering a pair of minimal geometries, we examine the tunneling conductance as a function of energy (e.g., chemical potential bias) at high and low energy limits, finding a low energy enhancement and a universal high versus zero energy relation that hold for all wire/bIQH edge combinations. Beyond this universality present in all the different topological (bIQH-edge) and nontopological (wire) setups, we also discover a number of features distinguishing the topological bIQH edges, which include a current imbalance to chemical potential bias ratio that is quantized despite the lack of conductance quantization in the bIQH edges themselves. The predicted phenomena require only initial states to be thermal and thus are well suited for tests with ultracold bosons forming wires and bIQH states. For the latter, we highlight a potential realization based on single component bosons in the recently observed Harper-Hofstadter band structure.

  12. Fractionally distilled SRC-I, SRC-II, EDS, H-Coal and ITSL direct coal liquefaction process materials: a comparative summary of chemical analysis and biological testing

    SciTech Connect

    Wright, C.W.; Later, D.W.; Dauble, D.D.; Wilson, B.W.

    1985-07-01

    This document reports and compares the results compiled from chemical analyses and biological testing of coal liquefaction process materials which were fractionally distilled, after production, into various comparable boiling-point range cuts. Comparative analyses were performed on solvent refined coal (SRC)-I, SRC-II, H-Coal, EDS an integrated two-stage liquefaction (ITSL) distillate materials. Mutagenicity and carcinogenicity assays were conducted in conjunction with chromatographic and mass spectrometric analyses to provide detailed, comparative, chemical and biological assessments. Where possible, results obtained from the distillate cuts are compared to those from coal liquefaction materials with limited boiling ranges. Work reported here was conducted by investigators in the Biology and Chemistry Department at the Pacific Northwest Laboratory (PNL), Richland, WA. 38 refs., 16 figs., 27 tabs.

  13. Hands-on equals minds-on? A test of linkage between laboratory experience and measured achievement in an introductory college biology course

    NASA Astrophysics Data System (ADS)

    Racich, Leo Peter 3rd

    This study investigated the specific contribution of laboratory experience to student performance on achievement tests in an introductory college biology course. This required pre-medical student course (900 students) was separated by the biology department into a lecture course and a laboratory course, creating the study groups. The topics selected for treatment were in the field of molecular biology, including restriction enzyme manipulation and plasmid mapping of DNA sequences. Random samples (30 per group) of students enrolled in the lecture course and laboratory course, lecture course only, or laboratory course only were post-tested and second post-tested for objective test achievement in the topical field after laboratory participation. Student self-reported essays on topical concept gains from laboratory experience were categorized and analyzed in relation to achievement outcomes. A significant difference (F = 5.47, df = 2,87, alpha = .05) was present within the group by test achievement scores. Analysis showed no significant difference in test scores over time for the laboratory and lecture and laboratory only groups. There was a significant decline in test scores for the lecture only group over time. Analysis of 509 student self-reported essays showed approximately 18.5% reporting no abstract comprehension gain from the specific laboratory experience they chose to report. Approximately 8.3% of the essays reported increased confusion of topical concepts after participating in the laboratory exercise. The balance of the students (73.3%) reported increased topical concept understanding after laboratory exercise participation. The results suggest the importance of laboratory participation for long-term concept retention and the benefit of post-laboratory experience reflection time before objective testing. Direct instruction without laboratory experience appears to yield gains which are short term in nature. Student self-reports suggested cognitive gains from

  14. Coupling field theory with mesoscopic dynamical simulations of multicomponent lipid bilayers.

    PubMed

    McWhirter, J Liam; Ayton, Gary; Voth, Gregory A

    2004-11-01

    A method for simulating a two-component lipid bilayer membrane in the mesoscopic regime is presented. The membrane is modeled as an elastic network of bonded points; the spring constants of these bonds are parameterized by the microscopic bulk modulus estimated from earlier atomistic nonequilibrium molecular dynamics simulations for several bilayer mixtures of DMPC and cholesterol. The modulus depends on the composition of a point in the elastic membrane model. The dynamics of the composition field is governed by the Cahn-Hilliard equation where a free energy functional models the coupling between the composition and curvature fields. The strength of the bonds in the elastic network are then modulated noting local changes in the composition and using a fit to the nonequilibrium molecular dynamics simulation data. Estimates for the magnitude and sign of the coupling parameter in the free energy model are made treating the bending modulus as a function of composition. A procedure for assigning the remaining parameters in the free energy model is also outlined. It is found that the square of the mean curvature averaged over the entire simulation box is enhanced if the strength of the bonds in the elastic network are modulated in response to local changes in the composition field. We suggest that this simulation method could also be used to determine if phase coexistence affects the stress response of the membrane to uniform dilations in area. This response, measured in the mesoscopic regime, is already known to be conditioned or renormalized by thermal undulations. PMID:15347594

  15. Mesoscopic turbulence and local order in Janus particles self-propelling under an ac electric field

    NASA Astrophysics Data System (ADS)

    Nishiguchi, Daiki; Sano, Masaki

    2015-11-01

    To elucidate mechanisms of mesoscopic turbulence exhibited by active particles, we experimentally study turbulent states of nonliving self-propelled particles. We realize an experimental system with dense suspensions of asymmetrical colloidal particles (Janus particles) self-propelling on a two-dimensional surface under an ac electric field. Velocity fields of the Janus particles in the crowded situation can be regarded as a sort of turbulence because it contains many vortices and their velocities change abruptly. Correlation functions of their velocity field reveal the coexistence of polar alignment and antiparallel alignment interactions, which is considered to trigger mesoscopic turbulence. Probability distributions of local order parameters for polar and nematic orders indicate the formation of local clusters with particles moving in the same direction. A broad peak in the energy spectrum of the velocity field appears at the spatial scales where the polar alignment and the cluster formation are observed. Energy is injected at the particle scale and conserved quantities such as energy could be cascading toward the larger clusters.

  16. Mesoscopic turbulence and local order in Janus particles self-propelling under an ac electric field.

    PubMed

    Nishiguchi, Daiki; Sano, Masaki

    2015-11-01

    To elucidate mechanisms of mesoscopic turbulence exhibited by active particles, we experimentally study turbulent states of nonliving self-propelled particles. We realize an experimental system with dense suspensions of asymmetrical colloidal particles (Janus particles) self-propelling on a two-dimensional surface under an ac electric field. Velocity fields of the Janus particles in the crowded situation can be regarded as a sort of turbulence because it contains many vortices and their velocities change abruptly. Correlation functions of their velocity field reveal the coexistence of polar alignment and antiparallel alignment interactions, which is considered to trigger mesoscopic turbulence. Probability distributions of local order parameters for polar and nematic orders indicate the formation of local clusters with particles moving in the same direction. A broad peak in the energy spectrum of the velocity field appears at the spatial scales where the polar alignment and the cluster formation are observed. Energy is injected at the particle scale and conserved quantities such as energy could be cascading toward the larger clusters. PMID:26651697

  17. Mesoscopic bar magnet based on ε-Fe2O3 hard ferrite

    PubMed Central

    Ohkoshi, Shin-ichi; Namai, Asuka; Yamaoka, Takehiro; Yoshikiyo, Marie; Imoto, Kenta; Nasu, Tomomichi; Anan, Shizuka; Umeta, Yoshikazu; Nakagawa, Kosuke; Tokoro, Hiroko

    2016-01-01

    Ferrite magnets have a long history. They are used in motors, magnetic fluids, drug delivery systems, etc. Herein we report a mesoscopic ferrite bar magnet based on rod-shaped ε-Fe2O3 with a large coercive field (>25 kOe). The ε-Fe2O3–based bar magnet is a single crystal with a single magnetic domain along the longitudinal direction. A wide frequency range spectroscopic study shows that the crystallographic a-axis of ε-Fe2O3, which corresponds to the longitudinal direction of the bar magnet, plays an important role in linear and non-linear magneto-optical transitions, phonon modes, and the magnon (Kittel mode). Due to its multiferroic property, a magnetic-responsive non-linear optical sheet is manufactured as an application using an ε-Fe2O3–based bar magnet, resin, and polyethylene terephthalate. Furthermore, from the viewpoint of the large coercive field property, we demonstrate that a mesoscopic ε-Fe2O3 bar magnet can be used as a magnetic force microscopy probe. PMID:27273575

  18. Surface-sensitive two-dimensional magneto-fingerprint in mesoscopic Bi2Se3 channels.

    PubMed

    Kandala, Abhinav; Richardella, Anthony; Zhang, Duming; Flanagan, Thomas C; Samarth, Nitin

    2013-06-12

    Periodic Aharonov–Bohm and Altshuler–Aronov–Spivak oscillations have traditionally been observed in lateral transport through patterned mesoscopic loops of diffusive conductors. However, our studies of perpendicular-to-plane magnetotransport in straight-channel, diffusive devices of epitaxial Bi2Se3 surprisingly reveal signatures of Aharonov–Bohm orbits, periodic conductance fluctuation magneto-fingerprints, even though the devices are not explicitly patterned into loops. We show that the length scale of these orbits corresponds to the typical perimeter of triangular terraces found on the surface of these thin film devices, strongly suggesting that the periodic magneto-fingerprint arises from coherent scattering of electron waves from the step-edges. Our interpretation is bolstered by control measurements in devices without such surface morphology that only show a conventional, aperiodic magneto-fingerprint. These results show that lithographically patterned Bi2Se3 devices provide a novel class of mesoscopic physical systems for systematic studies of coherent surface sensitive transport. PMID:23642037

  19. Dynamic responses of series parallel-plate mesoscopic capacitors to time-dependent external voltage

    NASA Astrophysics Data System (ADS)

    Wang, Jin-Hua; Quan, Jun

    2015-11-01

    We investigate the dynamic responses of the series parallel-plate mesoscopic capacitors to a time-dependent external voltage. The results indicate that the quantum coherence between two capacitors strongly depends on the frequency of the external voltage and the distance between the two capacitors (c-c distance). The behaviors of the series capacitance incompletely follow the Kirchhoff’s laws; only in the low frequency case or the limit of the c-c distance, the capacitance approaches to the classical series capacitance. In addition, the real part of the frequency-dependent capacitance shows a maximum and a minimum, which appear around the peak of the imaginary part. These phenomena may be associated with the plasmon excitation in the mesoscopic capacitors. Project supported by the National Natural Science Foundation of China (Grant No. 11304276), the Natural Science Foundation of Guangdong Province, China (Grant No. 2014A030307035), the Cultivation of Innovative Talents in Colleges and Universities of Guangdong Province, China (Grant No. LYM10098), and the Doctor Subject Foundation of Lingnan Normal University of China (Grant No. ZL1004).

  20. Thermodynamics of the mesoscopic thermoelectric heat engine beyond the linear-response regime

    NASA Astrophysics Data System (ADS)

    Yamamoto, Kaoru; Hatano, Naomichi

    2015-10-01

    Mesoscopic thermoelectric heat engine is much anticipated as a device that allows us to utilize with high efficiency wasted heat inaccessible by conventional heat engines. However, the derivation of the heat current in this engine seems to be either not general or described too briefly, even inappropriately in some cases. In this paper, we give a clear-cut derivation of the heat current of the engine with suitable assumptions beyond the linear-response regime. It resolves the confusion in the definition of the heat current in the linear-response regime. After verifying that we can construct the same formalism as that of the cyclic engine, we find the following two interesting results within the Landauer-Büttiker formalism: the efficiency of the mesoscopic thermoelectric engine reaches the Carnot efficiency if and only if the transmission probability is finite at a specific energy and zero otherwise; the unitarity of the transmission probability guarantees the second law of thermodynamics, invalidating Benenti et al.'s argument in the linear-response regime that one could obtain a finite power with the Carnot efficiency under a broken time-reversal symmetry [Phys. Rev. Lett. 106, 230602 (2011), 10.1103/PhysRevLett.106.230602]. These results demonstrate how quantum mechanics constrains thermodynamics.

  1. Mesoscopic Segregation of Excitation and Inhibition in a Brain Network Model

    PubMed Central

    Malagarriga, Daniel; Villa, Alessandro E. P.; Garcia-Ojalvo, Jordi; Pons, Antonio J.

    2015-01-01

    Neurons in the brain are known to operate under a careful balance of excitation and inhibition, which maintains neural microcircuits within the proper operational range. How this balance is played out at the mesoscopic level of neuronal populations is, however, less clear. In order to address this issue, here we use a coupled neural mass model to study computationally the dynamics of a network of cortical macrocolumns operating in a partially synchronized, irregular regime. The topology of the network is heterogeneous, with a few of the nodes acting as connector hubs while the rest are relatively poorly connected. Our results show that in this type of mesoscopic network excitation and inhibition spontaneously segregate, with some columns acting mainly in an excitatory manner while some others have predominantly an inhibitory effect on their neighbors. We characterize the conditions under which this segregation arises, and relate the character of the different columns with their topological role within the network. In particular, we show that the connector hubs are preferentially inhibitory, the more so the larger the node's connectivity. These results suggest a potential mesoscale organization of the excitation-inhibition balance in brain networks. PMID:25671573

  2. Mesoscopic deformation features of shocked porous ceramic: Polycrystalline modeling and experimental observations

    NASA Astrophysics Data System (ADS)

    Yu, Yin; Wang, Wenqiang; He, Hongliang; Jiang, Tailong; Huan, Qiang; Zhang, Fuping; Li, Yongqiang; Lu, Tiecheng

    2015-03-01

    To prevent functional failure, the macroscopic shock response of ceramics needs to be understood. We explored the mesoscopic deformation features of porous ceramics, which are responsible for the measured macroscopic "plastic" wave profiles, using polycrystalline modeling and experiments. A polycrystalline model is established that considers the influence of two major microstructures (multi-voids and grain boundaries) in the porous ceramics. Shock experiments with the recovery of shocked porous lead zirconate titanate ceramics were conducted. The computational results show that shear cracks nucleate around voids under shock because of severe shear stress concentrations. Broken fragments fill the voids and lead to void collapse. Representative long-distance extended cracks and thick crevices are observed in the recovered sample subjected to 3.3 GPa compression. These representative features are reproduced by the polycrystalline model. An initial transgranular crack translates into an intergranular crack after a certain propagation range to form a long-distance extended crack. Intergranular cracks branch from the main transgranular crack during main crack propagation to form a thick crevice. The simultaneous propagation of main and branching cracks results in a more effective shock energy dissipation. Slippage and rotation deformation induced by multi-cracks allows the shocked porous ceramic to deform even after all the voids have collapsed. Mesoscopic deformations of porous ceramics induce significant stress relaxations and lead to macroscopic "plastic" wave profiles. The polycrystalline model will aid microstructures design and provide guidance for preventing the shock failure of functional ceramics.

  3. Detecting weak coupling in mesoscopic systems with a nonequilibrium Fano resonance

    NASA Astrophysics Data System (ADS)

    Xiao, S.; Yoon, Y.; Lee, Y.-H.; Bird, J. P.; Ochiai, Y.; Aoki, N.; Reno, J. L.; Fransson, J.

    2016-04-01

    A critical aspect of quantum mechanics is the nonlocal nature of the wave function, a characteristic that may yield unexpected coupling of nominally isolated systems. The capacity to detect this coupling can be vital in many situations, especially those in which its strength is weak. In this work, we address this problem in the context of mesoscopic physics, by implementing an electron-wave realization of a Fano interferometer using pairs of coupled quantum point contacts (QPCs). Within this scheme, the discrete level required for a Fano resonance is provided by pinching off one of the QPCs, thereby inducing the formation of a quasibound state at the center of its self-consistent potential barrier. Using this system, we demonstrate a form of nonequilibrium Fano resonance (NEFR), in which nonlinear electrical biasing of the interferometer gives rise to pronounced distortions of its Fano resonance. Our experimental results are captured well by a quantitative theoretical model, which considers a system in which a standard two-path Fano interferometer is coupled to an additional, intruder, continuum. According to this theory, the observed distortions in the Fano resonance arise only in the presence of coupling to the intruder, indicating that the NEFR provides a sensitive means to infer the presence of weak coupling between mesoscopic systems.

  4. Mesoscopic segregation of excitation and inhibition in a brain network model.

    PubMed

    Malagarriga, Daniel; Villa, Alessandro E P; Garcia-Ojalvo, Jordi; Pons, Antonio J

    2015-02-01

    Neurons in the brain are known to operate under a careful balance of excitation and inhibition, which maintains neural microcircuits within the proper operational range. How this balance is played out at the mesoscopic level of neuronal populations is, however, less clear. In order to address this issue, here we use a coupled neural mass model to study computationally the dynamics of a network of cortical macrocolumns operating in a partially synchronized, irregular regime. The topology of the network is heterogeneous, with a few of the nodes acting as connector hubs while the rest are relatively poorly connected. Our results show that in this type of mesoscopic network excitation and inhibition spontaneously segregate, with some columns acting mainly in an excitatory manner while some others have predominantly an inhibitory effect on their neighbors. We characterize the conditions under which this segregation arises, and relate the character of the different columns with their topological role within the network. In particular, we show that the connector hubs are preferentially inhibitory, the more so the larger the node's connectivity. These results suggest a potential mesoscale organization of the excitation-inhibition balance in brain networks. PMID:25671573

  5. Percolation transition at growing spatiotemporal fractal patterns in models of mesoscopic neural networks.

    PubMed

    Franović, Igor; Miljković, Vladimir

    2009-06-01

    Spike packet propagation is modeled in mesoscopic-scale networks, composed of locally and recurrently coupled neural pools, and embedded in a two-dimensional lattice. Site dynamics is governed by three key parameters--pool connectedness probability, synaptic strength (following the steady-state distribution of some realizations of spike-timing-dependent plasticity learning rule), and the neuron refractoriness. Formation of spatiotemporal patterns in our model, synfire chains, exhibits critical behavior, with the emerging percolation phase transition controlled by the probability for nonzero synaptic strength value. Applying the finite-size scaling method, we infer the critical probability dependence on synaptic strength and refractoriness and determine the effects of connection topology on the pertaining percolation clusters fractal dimensions. We find that the directed percolation and the pair contact process with diffusion constitute the relevant universality classes of phase transitions observed in a class of mesoscopic-scale network models, which may be related to recently reported data on in vitro cultures. PMID:19658540

  6. Mesoscopic bar magnet based on ε-Fe2O3 hard ferrite

    NASA Astrophysics Data System (ADS)

    Ohkoshi, Shin-Ichi; Namai, Asuka; Yamaoka, Takehiro; Yoshikiyo, Marie; Imoto, Kenta; Nasu, Tomomichi; Anan, Shizuka; Umeta, Yoshikazu; Nakagawa, Kosuke; Tokoro, Hiroko

    2016-06-01

    Ferrite magnets have a long history. They are used in motors, magnetic fluids, drug delivery systems, etc. Herein we report a mesoscopic ferrite bar magnet based on rod-shaped ε-Fe2O3 with a large coercive field (>25 kOe). The ε-Fe2O3–based bar magnet is a single crystal with a single magnetic domain along the longitudinal direction. A wide frequency range spectroscopic study shows that the crystallographic a-axis of ε-Fe2O3, which corresponds to the longitudinal direction of the bar magnet, plays an important role in linear and non-linear magneto-optical transitions, phonon modes, and the magnon (Kittel mode). Due to its multiferroic property, a magnetic-responsive non-linear optical sheet is manufactured as an application using an ε-Fe2O3–based bar magnet, resin, and polyethylene terephthalate. Furthermore, from the viewpoint of the large coercive field property, we demonstrate that a mesoscopic ε-Fe2O3 bar magnet can be used as a magnetic force microscopy probe.

  7. A mesoscopic reaction rate model for shock initiation of multi-component PBX explosives.

    PubMed

    Liu, Y R; Duan, Z P; Zhang, Z Y; Ou, Z C; Huang, F L

    2016-11-01

    The primary goal of this research is to develop a three-term mesoscopic reaction rate model that consists of a hot-spot ignition, a low-pressure slow burning and a high-pressure fast reaction terms for shock initiation of multi-component Plastic Bonded Explosives (PBX). Thereinto, based on the DZK hot-spot model for a single-component PBX explosive, the hot-spot ignition term as well as its reaction rate is obtained through a "mixing rule" of the explosive components; new expressions for both the low-pressure slow burning term and the high-pressure fast reaction term are also obtained by establishing the relationships between the reaction rate of the multi-component PBX explosive and that of its explosive components, based on the low-pressure slow burning term and the high-pressure fast reaction term of a mesoscopic reaction rate model. Furthermore, for verification, the new reaction rate model is incorporated into the DYNA2D code to simulate numerically the shock initiation process of the PBXC03 and the PBXC10 multi-component PBX explosives, and the numerical results of the pressure histories at different Lagrange locations in explosive are found to be in good agreements with previous experimental data. PMID:27258213

  8. Diffuse phase transition in ferroelectrics with mesoscopic heterogeneity: Mean-field theory

    SciTech Connect

    Li, S.; Eastman, J.A.; Newnham, R.E.; Cross, L.E.

    1997-05-01

    The diffuse phase transition in ferroelectrics with mesoscopic heterogeneity has been discussed within the context of a superparaelectric model by using the Ginzburg-Landau formalism. In the Curie region ferroelectrics with mesoscopic heterogeneity are treated as {open_quotes}superparaelectrics{close_quotes} consisting of a mass of polar clusters, each of which has Ising character. Based on the mean-field theory, the influence of the finite-size effects of polar clusters on their structural instability has been discussed by considering a coherent lattice coupling between two structurally different regions. In particular, we have analytically derived the explicit solutions of the distribution of local polarizations. In turn, the processes of polar nanophase precipitation and coarsening have been also discussed in conjunction with the local chemical or structural inhomogeneity. Moreover, we have also analyzed the relationship between the local polarization distribution and the static dielectric susceptibility in ferroelectrics with the nanometric scale heterogeneity. The width of the Curie region is dependent upon the distribution of the sum of localized correlation length, which reflects the size distribution of heterogeneity. The presented analysis reveals that the diffuse phase transition is closely associated with the existence of nanometric polar clusters and their physical size distribution. Intriguingly, our theoretical results bear a very close resemblance to most experimental observations. {copyright} {ital 1997} {ital The American Physical Society}

  9. Mesoscopic bar magnet based on ε-Fe2O3 hard ferrite.

    PubMed

    Ohkoshi, Shin-Ichi; Namai, Asuka; Yamaoka, Takehiro; Yoshikiyo, Marie; Imoto, Kenta; Nasu, Tomomichi; Anan, Shizuka; Umeta, Yoshikazu; Nakagawa, Kosuke; Tokoro, Hiroko

    2016-01-01

    Ferrite magnets have a long history. They are used in motors, magnetic fluids, drug delivery systems, etc. Herein we report a mesoscopic ferrite bar magnet based on rod-shaped ε-Fe2O3 with a large coercive field (>25 kOe). The ε-Fe2O3-based bar magnet is a single crystal with a single magnetic domain along the longitudinal direction. A wide frequency range spectroscopic study shows that the crystallographic a-axis of ε-Fe2O3, which corresponds to the longitudinal direction of the bar magnet, plays an important role in linear and non-linear magneto-optical transitions, phonon modes, and the magnon (Kittel mode). Due to its multiferroic property, a magnetic-responsive non-linear optical sheet is manufactured as an application using an ε-Fe2O3-based bar magnet, resin, and polyethylene terephthalate. Furthermore, from the viewpoint of the large coercive field property, we demonstrate that a mesoscopic ε-Fe2O3 bar magnet can be used as a magnetic force microscopy probe. PMID:27273575

  10. Thermodynamics of the mesoscopic thermoelectric heat engine beyond the linear-response regime.

    PubMed

    Yamamoto, Kaoru; Hatano, Naomichi

    2015-10-01

    Mesoscopic thermoelectric heat engine is much anticipated as a device that allows us to utilize with high efficiency wasted heat inaccessible by conventional heat engines. However, the derivation of the heat current in this engine seems to be either not general or described too briefly, even inappropriately in some cases. In this paper, we give a clear-cut derivation of the heat current of the engine with suitable assumptions beyond the linear-response regime. It resolves the confusion in the definition of the heat current in the linear-response regime. After verifying that we can construct the same formalism as that of the cyclic engine, we find the following two interesting results within the Landauer-Büttiker formalism: the efficiency of the mesoscopic thermoelectric engine reaches the Carnot efficiency if and only if the transmission probability is finite at a specific energy and zero otherwise; the unitarity of the transmission probability guarantees the second law of thermodynamics, invalidating Benenti et al.'s argument in the linear-response regime that one could obtain a finite power with the Carnot efficiency under a broken time-reversal symmetry [Phys. Rev. Lett. 106, 230602 (2011)]. These results demonstrate how quantum mechanics constrains thermodynamics. PMID:26565226

  11. Electronic transport properties in random one-dimensional chains containing mesoscopic-ring defects

    NASA Astrophysics Data System (ADS)

    Huang, X.

    1999-11-01

    We study the electronic transport properties in one-dimensional systems with two kinds of mesoscopic ring defects: squarelike mesoscopic ring (SMR) defects and siamese-twins-like mescoscopic ring (STMR) defects. By using the transfer-matrix method, the resonant energies (where the transmission coefficient T=1) are derived successfully for both system. For the one SMR defect system, two resonant energies are found as a function of the magnetic flux Φ threading the ring defect, while for the latter case, two magnetic-flux-dependent and one magnetic-flux-independent resonant energies are predicted in the system, furthermore, if Φ takes some specific values, one of the Φ-dependent resonant energies may be the same as the Φ-independent resonant energy. The word ``resonant'' is used to describe this situation. When a finite concentration of SMR or STMR defects are randomly embedded in a perfect chain, the numerical results confirm all the analytical predictions. Finally, for the ``resonant'' case, we show numerically a rather wide perfect transmission region which is almost ten times as wide as that of the ``unresonant'' case.

  12. Decommissioning samples from the Ft. Lewis, WA, solvent refined coal pilot plant: chemical analysis and biological testing

    SciTech Connect

    Weimer, W.C.; Wright, C.W.

    1985-10-01

    This report presents the results from chemical analyses and limited biological assays of three sets of samples from the Ft. Lewis, WA solvent refined coal (SRC) pilot plant. The samples were collected during the process of decommissioning this facility. Chemical composition was determined for chemical class fractions of the samples by using high-resolution gas chromatography (GC), high-resolution GC/mass spectrometry (MS) and high-resolution MS. Biological activity was measuring using both the histidine reversion microbial mutagenicity assay with Salmonella typhimurium, TA98 and an initiation/promotion mouse-skin tumorigenicity assay. 19 refs., 7 figs., 27 tabs.

  13. Testing a model of science process skills acquisition: An interaction with parents' education, preferred language, gender, science attitude, cognitive development, academic ability, and biology knowledge

    NASA Astrophysics Data System (ADS)

    Germann, Paul J.

    Path analysis techniques were used to test a hypothesized structural model of direct and indirect causal effects of student variables on science process skills. The model was tested twice using data collected at the beginning and end of the school year from 67 9th- and 10th-grade biology students who lived in a rural Franco-American community in New England. Each student variable was found to have significant effects, accounting for approximately 80% of the variance in science process skills achievement. Academic ability, biology knowledge, and language preference had significant direct effects. There were significant mediated effects by cognitive development, parents' education, and attitude toward science in school. The variables of cognitive development and academic ability had the greatest total effects on science process skills. Implications for practitioners and researchers are discussed.

  14. Otoconia as test masses in biological accelerometers: what can we learn about their formation from evolutionary studies and from work in microgravity?

    NASA Technical Reports Server (NTRS)

    Ross, M. D.; Donovan, K. M.

    1986-01-01

    This paper reviews previous findings and introduces new material about otolith end organs that help us to understand their functioning and development. In particular, we consider the end organs as biological accelerometers. The otoconia are dealt with as test masses whose substructure and evolutionary trend toward calcite may prove significant in understanding formation requirements. Space-flight helps illuminate the influence of gravity, while right-left asymmetry is suggested by study of certain rat strains.

  15. Enhancement of persistent current in mesoscopic rings and cylinders: shortest and next possible shortest higher-order hopping

    NASA Astrophysics Data System (ADS)

    Maiti, Santanu K.; Chowdhury, J.; Karmakar, S. N.

    2006-06-01

    We present a detailed study of persistent current and low-field magnetic susceptibility in single isolated normal metal mesoscopic rings and cylinders in the tight-binding model with higher-order hopping integral in the Hamiltonian. Our exact calculations show that order of magnitude enhancement of persistent current takes place even in the presence of disorder if we include the higher-order hopping integral in the Hamiltonian. In strictly one-channel mesoscopic rings the sign of the low-field currents can be predicted exactly even in the presence of impurity. We observe that perfect rings with both odd and even numbers of electrons support only diamagnetic currents. On the other hand in the disordered rings, irrespective of realization of the disordered configurations of the ring, we always get diamagnetic currents with odd numbers of electrons and paramagnetic currents with even numbers of electrons. In mesoscopic cylinders the sign of the low-field currents cannot be predicted exactly since it strongly depends on the total number of electrons, Ne, and also on the disordered configurations of the system. From the variation of persistent current amplitude with system size for constant electron density, we conclude that the enhancement of persistent current due to additional higher-order hopping integrals is visible only in the mesoscopic regime.

  16. Using Models at the Mesoscopic Scale in Teaching Physics: Two Experimental Interventions in Solid Friction and Fluid Statics

    ERIC Educational Resources Information Center

    Besson, Ugo; Viennot, Laurence

    2004-01-01

    This article examines the didactic suitability of introducing models at an intermediate (i.e. mesoscopic) scale in teaching certain subjects, at an early stage. The design and evaluation of two short sequences based on this rationale will be outlined: one bears on propulsion by solid friction, the other on fluid statics in the presence of gravity.…

  17. Testing Models: A Key Aspect to Promote Teaching Activities Related to Models and Modelling in Biology Lessons?

    ERIC Educational Resources Information Center

    Krell, Moritz; Krüger, Dirk

    2016-01-01

    This study investigated biology teachers' (N = 148) understanding of models and modelling (MoMo), their model-related teaching activities and relations between the two. A framework which distinguishes five aspects of MoMo in science ("nature of models," "multiple models," "purpose of models," "testing…

  18. The Effects of Co-Teaching on Student Test Performance and Attitudes towards Science in High School Biology

    ERIC Educational Resources Information Center

    Cole, Virginia Scott

    2009-01-01

    Reform efforts in response to the inclusion of students with disabilities into general education classrooms have become necessary to shift students' placements into the science classroom. An investigation into the effects of co-teaching in high school biology classrooms was conducted to explore the impact of two models of co-teaching on biology…

  19. The androgen receptor and its use in biological assays: looking toward effect-based testing and its applications.

    PubMed

    Cadwallader, Amy B; Lim, Carol S; Rollins, Douglas E; Botrè, Francesco

    2011-11-01

    Steroid abuse is a growing problem among amateur and professional athletes. Because of an inundation of newly and illegally synthesized steroids with minor structural modifications and other designer steroid receptor modulators, there is a need to develop new methods of detection which do not require prior knowledge of the abused steroid structure. The number of designer steroids currently being abused is unknown because detection methods in general are only identifying substances with a known structure. The detection of doping is moving away from merely checking for exposure to prohibited substance toward detecting an effect of prohibited substances, as biological assays can do. Cell-based biological assays are the next generation of assays which should be utilized by antidoping laboratories; they can detect androgenic anabolic steroid and other human androgen receptor (hAR) ligand presence without knowledge of their structure and assess the relative biological activity of these compounds. This review summarizes the hAR and its action and discusses its relevance to sports doping and its use in biological assays. PMID:22080898

  20. The Androgen Receptor and Its Use in Biological Assays: Looking Toward Effect-Based Testing and Its Applications

    PubMed Central

    Cadwallader, Amy B.; Lim, Carol S.; Rollins, Douglas E.; Botrè, Francesco

    2015-01-01

    Steroid abuse is a growing problem among amateur and professional athletes. Because of an inundation of newly and illegally synthesized steroids with minor structural modifications and other designer steroid receptor modulators, there is a need to develop new methods of detection which do not require prior knowledge of the abused steroid structure. The number of designer steroids currently being abused is unknown because detection methods in general are only identifying substances with a known structure. The detection of doping is moving away from merely checking for exposure to prohibited substance toward detecting an effect of prohibited substances, as biological assays can do. Cell-based biological assays are the next generation of assays which should be utilized by antidoping laboratories; they can detect androgenic anabolic steroid and other human androgen receptor (hAR) ligand presence without knowledge of their structure and assess the relative biological activity of these compounds. This review summarizes the hAR and its action and discusses its relevance to sports doping and its use in biological assays. PMID:22080898

  1. Concepts and Tests for the Remote-Controlled Dismantling of the Biological Shield and Form work of the KNK Reactor - 13425

    SciTech Connect

    Neff, Sylvia; Graf, Anja; Petrick, Holger; Rothschmitt, Stefan; Klute, Stefan

    2013-07-01

    The compact sodium-cooled nuclear reactor facility Karlsruhe (KNK), a prototype Fast Breeder, is currently in an advanced stage of dismantling. Complete dismantling is based on 10 partial licensing steps. In the frame of the 9. decommissioning permit, which is currently ongoing, the dismantling of the biological shield is foreseen. The biological shield consists of heavy reinforced concrete with built-in steel fitments, such as form-work of the reactor tank, pipe sleeves, ventilation channels, and measuring devices. Due to the activation of the inner part of the biological shield, dismantling has to be done remote-controlled. During a comprehensive basic design phase a practical dismantling strategy was developed. Necessary equipment and tools were defined. Preliminary tests revealed that hot wire plasma cutting is the most favorable cutting technology due to the geometrical boundary conditions, the varying distance between cutter and material, and the heavy concrete behind the steel form-work. The cutting devices will be operated remotely via a carrier system with an industrial manipulator. The carrier system has expandable claws to adjust to the varying diameter of the reactor shaft during dismantling progress. For design approval of this prototype development, interaction between manipulator and hot wire plasma cutting was tested in a real configuration. For the demolition of the concrete structure, an excavator with appropriate tools, such as a hydraulic hammer, was selected. Other mechanical cutting devices, such as a grinder or rope saw, were eliminated because of concrete containing steel spheres added to increase the shielding factor of the heavy concrete. Dismantling of the biological shield will be done in a ring-wise manner due to static reasons. During the demolition process, the excavator is positioned on its tripod in three concrete recesses made prior to the dismantling of the separate concrete rings. The excavator and the manipulator carrier system

  2. Guided self-assembly and directed restructuring of mesoscopic silica using electric fields

    NASA Astrophysics Data System (ADS)

    Ku, Anthony Yu-Chung

    Surfactant-templated synthesis of ceramics has received considerable attention due to the ease with which these methods produce materials with well-controlled nanometer-sized porosity. A key limitation with this approach is the pores produced by the surfactant template do not always adopt the desired long-range order. Specifically, the ability to straighten the pores, orient them in desired directions, and eliminate domain boundaries must be improved in order for these materials to be useful as membranes for filtration, sensing or catalysis. One solution to this problem is to guide the self-assembly using applied fields. The idea is to produce short-range order using self-assembly while generating long-range order using the field. Electric fields are an intriguing option because they are easily controlled and can produce orientation in different directions. Recent work by Trau et al. found that mesoscopic silica prepared under the combined influence of high strength electric fields, surface registry and confinement effects possessed oriented nanochannels. The goal of this project was to study the effects of electric fields on surfactant-templated mesoscopic silica. It was found that low strength (E ˜ 200 V/m) electric fields can both guide the self-assembly of the structure as it forms and alter the organization of material that has already ordered. This is the first demonstration of the latter effect in a templated ceramic system. Experimentally, micron-sized particles transformed into continuous fibers under the influence of the field. This macroscopic change in morphology was accompanied by alignment of the surfactant-templated pores in the direction of the field. Quantitative analysis of the response indicates these structural changes occur through an electrokinetic mechanism rather than dielectric polarization. The distinction is important as electrokinetic phenomena arise from the action of a field on free charge while polarization depends on the dielectric

  3. Efficiency of biological activator formulated material (BAFM) for volatile organic compounds removal--preliminary batch culture tests with activated sludge.

    PubMed

    Corre, Charline; Couriol, Catherine; Amrane, Abdeltif; Dumont, Eric; Andrès, Yves; Le Cloirec, Pierre

    2012-01-01

    During biological degradation, such as biofiltration of air loaded with volatile organic compounds, the pollutant is passed through a bed packed with a solid medium acting as a biofilm support. To improve microorganism nutritional equilibrium and hence to enhance the purification capacities, a Biological Activator Formulated Material (BAFM) was developed, which is a mixture of solid nutrients dissolving slowly in a liquid phase. This solid was previously validated on mineral pollutants: ammonia and hydrogen sulphide. To evaluate the efficiency of such a material for biodegradation of some organic compounds, a simple experiment using an activated sludge batch reactor was carried out. The pollutants (sodium benzoate, phenol, p-nitrophenol and 2-4-dichlorophenol) were in the concentration range 100 to 1200 mg L(-1). The positive impact of the formulated material was shown. The improvement of the degradation rates was in the range 10-30%. This was the consequence of the low dissolution of the nutrients incorporated during material formulation, followed by their consumption by the biomass, as shown for urea used as a nitrogen source. Owing to its twofold interest (mechanical resistance and nutritional supplementation), the Biological Activator Formulated Material seems to be a promising material. Its addition to organic or inorganic supports should be investigated to confirm its relevance for implementation in biofilters. PMID:22988627

  4. Design of a new monitoring network and first testing of new biological assessment methods according to water framework directive.

    PubMed

    Sommerhäuser, Mario; Scharner, Christoph; Schimmer, Hannes; Schindler, Anna; Plantikow, Kerstin; Vietoris, Friederike

    2007-09-01

    In most European member states, more or less completely new monitoring networks and assessment methods had to be developed as basic technical tools for the implementation of the EU Water Framework Directive (WFD). In the river basin of the Stever, the largest tributary to the river Lippe (River Rhine, Northrhine-Westphalia, Germany), a WFD-monitoring network was developed, and new German biological methods for rivers, developed for the purposes of the WFD, have been applied. Like most rivers in the German lowland areas, nearly all the river courses of the Stever system are altered by hydro-morphological degradation (straightening, bank fixation, lack of canopy etc.). In 2005 and 2006, the biological quality components of macroinvertebrates, fish and macrophytes were investigated and evaluated for the assessment of the ecological status of about 50 surface water bodies within the whole Stever system. Basic physical and chemical parameters, as well as priority substances, have been analysed in the same period. In this contribution, the design of the new monitoring network, the core principles of the German biological methods, and the most important results of the pilot monitoring will be presented. As main impacts with severe effects on the faunal and floral communities, the many migration barriers and the bad quality of the river morphology could be stated. Organic pollution is no more a severe problem in the Stever. The pilot project was successfully conducted in close collaboration with the water authorities (District Government Münster) and the water association Lippeverband. PMID:17726557

  5. Two-stage coal liquefaction process materials from the Wilsonville Facility operated in the nonintegrated and integrated modes: chemical analyses and biological testing

    SciTech Connect

    Later, D.W.

    1985-01-01

    This document reports the results from chemical analyses and biological testing of process materials sampled during operation of the Wilsonville Advanced Coal Liquefaction Research and Development Facility (Wilsonville, Alabama) in both the noncoupled or nonintegrated (NTSL Run 241) and coupled or integrated (ITSL Run 242) two-stage liquefaction operating modes. Mutagenicity and carcinogenicity assays were conducted in conjunction with chromatographic and mass spectrometric analyses to provide detailed, comparative chemical and biological assessments of several NTSL and ITSL process materials. In general, the NTSL process materials were biologically more active and chemically more refractory than analogous ITSL process materials. To provide perspective, the NTSL and ITSL results are compared with those from similar testing and analyses of other direct coal liquefaction materials from the solvent refined coal (SRC) I, SRC II and EDS processes. Comparisons are also made between two-stage coal liquefaction materials from the Wilsonville pilot plant and the C.E. Lummus PDU-ITSL Facility in an effort to assess scale-up effects in these two similar processes. 36 references, 26 figures, 37 tables.

  6. Four-terminal resistances in mesoscopic networks of metallic wires: Weak localisation and correlations

    NASA Astrophysics Data System (ADS)

    Texier, Christophe; Montambaux, Gilles

    2016-01-01

    We consider the electronic transport in multi-terminal mesoscopic networks of weakly disordered metallic wires. After a brief description of the classical transport, we analyse the weak localisation (WL) correction to the four-terminal resistances, which involves an integration of the Cooperon over the wires with proper weights. We provide an interpretation of these weights in terms of classical transport properties. We illustrate the formalism on examples and show that weak localisation to four-terminal conductances may become large in some situations. In a second part, we study the correlations of four-terminal resistances and show that integration of Diffuson and Cooperon inside the network involves the same weights as the WL. The formulae are applied to multiconnected wire geometries.

  7. Modeling snow-crystal growth: a three-dimensional mesoscopic approach.

    PubMed

    Gravner, Janko; Griffeath, David

    2009-01-01

    We introduce a three-dimensional, computationally feasible, mesoscopic model for snow-crystal growth, based on diffusion of vapor, anisotropic attachment, and a boundary layer. Several case studies are presented that faithfully replicate most observed snow-crystal morphology, an unusual achievement for a mathematical model. In particular, many of the most striking physical specimens feature both facets and branches, and our model provides an explanation for this phenomenon. We also duplicate many other observed traits, including ridges, ribs, sandwich plates, and hollow columns, as well as various dynamic instabilities. The concordance of observed phenomena suggests that the ingredients in our model are the most important ones in the development of physical snow crystals. PMID:19257039

  8. Mesoscopic simulation of phase behaviors and structures in an amphiphile-solvent system

    NASA Astrophysics Data System (ADS)

    Yamada, Kohtaro; Yasuno, Emiko; Kawabata, Youhei; Okuzono, Tohru; Kato, Tadashi

    2014-06-01

    We have performed a three-dimensional simulation of mesoscopic structures in a mixture of AB amphiphilic molecule and C solvent by employing the density-functional theory under the conditions that (i) the size of the AB is much larger than C and (ii) the affinity between A and B is much larger than the affinity between B and C. First, we have calculated the free energy of five periodic structures, i.e., the lamellar phase, hexagonally packed cylinders, body-centered-cubic spheres, face-centered-cubic spheres, and gyroid phase for different sets of the concentration of AB (ϕ¯AB) and the χ parameter (χAC). By comparing the free energies for these structures, the χAC-ϕ ¯AB phase diagram has been obtained. In addition to these periodic structures, it has been shown that nonperiodic structures such as spherical and rodlike micelles can be obtained although they might be metastable phase.

  9. Controlling the quantum dynamics of a mesoscopic spin bath in diamond

    PubMed Central

    de Lange, Gijs; van der Sar, Toeno; Blok, Machiel; Wang, Zhi-Hui; Dobrovitski, Viatcheslav; Hanson, Ronald

    2012-01-01

    Understanding and mitigating decoherence is a key challenge for quantum science and technology. The main source of decoherence for solid-state spin systems is the uncontrolled spin bath environment. Here, we demonstrate quantum control of a mesoscopic spin bath in diamond at room temperature that is composed of electron spins of substitutional nitrogen impurities. The resulting spin bath dynamics are probed using a single nitrogen-vacancy (NV) centre electron spin as a magnetic field sensor. We exploit the spin bath control to dynamically suppress dephasing of the NV spin by the spin bath. Furthermore, by combining spin bath control with dynamical decoupling, we directly measure the coherence and temporal correlations of different groups of bath spins. These results uncover a new arena for fundamental studies on decoherence and enable novel avenues for spin-based magnetometry and quantum information processing. PMID:22536480

  10. Balanced double-loop mesoscopic interferometer based on Josephson proximity nanojunctions

    SciTech Connect

    Ronzani, Alberto Altimiras, Carles; Giazotto, Francesco

    2014-01-20

    We report on the fabrication and characterization of a two-terminal mesoscopic interferometer based on three V/Cu/V Josephson junctions having nanoscale cross-section. The junctions have been arranged in a double-ring geometry realized by metallic thin film deposition through a suspended mask defined by electron beam lithography. Although a significant amount of asymmetry between the critical current of each junction is observed, we show that the interferometer is able to suppress the supercurrent to a level lower than 6 parts per thousand, being here limited by measurement resolution. The present nano-device is suitable for low-temperature magnetometric and gradiometric measurements over the micrometric scale.

  11. Paramagnetic reentrant effect in high purity mesoscopic AgNb proximity structures

    PubMed

    Muller-Allinger; Mota

    2000-04-01

    We discuss the magnetic response of clean Ag coated Nb proximity cylinders in the temperature range 150 &mgr;Kmesoscopic temperature regime, the normal-metal-superconductor system shows the yet unexplained paramagnetic reentrant effect, discovered some years ago [P. Visani, A. C. Mota, and A. Pollini, Phys. Rev. Lett. 65, 1514 (1990)], superimposing on full Meissner screening. The logarithmic slope of the reentrant paramagnetic susceptibility chi(para)(T) approximately exp(-L/xi(N)) is limited by the condition xi(N) = n L, with xi(N) = Planck's over 2piv(F)/2pik(B)T, the thermal coherence length and n = 1,2,4. At the lowest temperatures, chi(para) compensates the diamagnetic susceptibility of the whole AgNb structure. PMID:11019037

  12. Mesoscopic quantum superposition of the generalized cat state: A diffraction limit

    NASA Astrophysics Data System (ADS)

    Ghosh, Suranjana; Sharma, Raman; Roy, Utpal; Panigrahi, Prasanta K.

    2015-11-01

    The orthogonality of cat and displaced cat states, underlying Heisenberg limited measurement in quantum metrology, is studied in the limit of a large number of states. The mesoscopic superposition of the generalized cat state is correlated with the corresponding state overlap function, controlled by the sub-Planck structures arising from phase-space interference. The asymptotic expression of this overlap function is evaluated, and the validity of large phase-space support and distinguishability of the constituent states, in which context the asymptotic limit is achieved, are discussed in detail. For a large number of coherent states, uniformly located on a circle, the overlap function significantly matches the diffraction pattern for a circular ring source with uniform angular strength. This is in accordance with the van Cittert-Zernike theorem, where the overlap function, similar to the mutual coherence function, matches a diffraction pattern. The physical situation under consideration is delineated in phase space by utilizing the Husimi Q function.

  13. Revealing the flux: Using processed Husimi maps to visualize dynamics of bound systems and mesoscopic transport

    NASA Astrophysics Data System (ADS)

    Mason, Douglas J.; Borunda, Mario F.; Heller, Eric J.

    2015-04-01

    We elaborate upon the "processed Husimi map" representation for visualizing quantum wave functions using coherent states as a measurement of the local phase space to produce a vector field related to the probability flux. Adapted from the Husimi projection, the processed Husimi map is mathematically related to the flux operator under certain limits but offers a robust and flexible alternative since it can operate away from these limits and in systems that exhibit zero flux. The processed Husimi map is further capable of revealing the full classical dynamics underlying a quantum wave function since it reverse engineers the wave function to yield the underlying classical ray structure. We demonstrate the capabilities of processed Husimi maps on bound systems with and without electromagnetic fields, as well as on open systems on and off resonance, to examine the relationship between closed system eigenstates and mesoscopic transport.

  14. Broadband giant-refractive-index material based on mesoscopic space-filling curves.

    PubMed

    Chang, Taeyong; Kim, Jong Uk; Kang, Seung Kyu; Kim, Hyowook; Kim, Do Kyung; Lee, Yong-Hee; Shin, Jonghwa

    2016-01-01

    The refractive index is the fundamental property of all optical materials and dictates Snell's law, propagation speed, wavelength, diffraction, energy density, absorption and emission of light in materials. Experimentally realized broadband refractive indices remain <40, even with intricately designed artificial media. Herein, we demonstrate a measured index >1,800 resulting from a mesoscopic crystal with a dielectric constant greater than three million. This gigantic enhancement effect originates from the space-filling curve concept from mathematics. The principle is inherently very broad band, the enhancement being nearly constant from zero up to the frequency of interest. This broadband giant-refractive-index medium promises not only enhanced resolution in imaging and raised fundamental absorption limits in solar energy devices, but also compact, power-efficient components for optical communication and increased performance in many other applications. PMID:27573337

  15. Mesoscopic Metal-Insulator Transition at Ferroelastic Domain Walls in VO2

    SciTech Connect

    Jones, Keith M; Kalinin, Sergei V; Kolmakov, Andrei; Luk'yanchuk, Prof. Igor A.; Meunier, Vincent; Proksch, Roger; Shelton Jr, William Allison; Strelcov, Evgheni; Tselev, Alexander

    2010-01-01

    The novel phenomena induced by symmetry breaking at homointerfaces between ferroic variants in ferroelectric and ferroelastic materials have attracted recently much attention. Using variable temperature scanning microwave microscopy, we demonstrate the mesoscopic strain-induced metal-insulator phase transitions in the vicinity of ferroelastic domain walls in the semiconductive VO2 that nucleated at temperatures as much as 10-12 C below bulk transition, resulting in the formation of conductive channels in the material. Density functional theory is used to rationalize the process low activation energy. This behavior, linked to the strain inhomogeneity inherent in ferroelastic materials, can strongly affect interpretation of phase-transition studies in VO2 and similar materials with symmetry-lowering transitions, and can also be used to enable new generations of electronic devices though strain engineering of conductive and semiconductive regions.

  16. Ex situ elaborated proximity mesoscopic structures for ultrahigh vacuum scanning tunneling spectroscopy

    SciTech Connect

    Stolyarov, V. S.; Cren, T. Debontridder, F.; Brun, C.; Veshchunov, I. S.; Skryabina, O. V.; Rusanov, A. Yu.; Roditchev, D.

    2014-04-28

    We apply ultrahigh vacuum Scanning Tunneling Spectroscopy (STS) at ultra-low temperature to study proximity phenomena in metallic Cu in contact with superconducting Nb. In order to solve the problem of Cu-surface contamination, Cu(50 nm)/Nb(100 nm) structures are grown by respecting the inverted order of layers on SiO{sub 2}/Si substrate. Once transferred into vacuum, the samples are cleaved at the structure-substrate interface. As a result, a contamination-free Cu-surface is exposed in vacuum. It enables high-resolution STS of superconducting correlations induced by proximity from the underlying superconducting Nb layer. By applying magnetic field, we generate unusual proximity-induced superconducting vortices and map them with a high spatial and energy resolution. The suggested method opens a way to access local electronic properties of complex electronic mesoscopic devices by performing ex situ STS under ultrahigh vacuum.

  17. Tsallis, Rényi, and Shannon entropies for time-dependent mesoscopic RLC circuits

    NASA Astrophysics Data System (ADS)

    Aguiar, V.; Guedes, I.; Pedrosa, I. A.

    2015-11-01

    We calculate information measures using the Tsallis, Rényi, and Shannon entropies for two classes (Lane-Emden and Caldirola-Kanai) of time-dependent mesoscopic RLC circuits. To determine the expressions for the entropies, we used the dynamical invariant method to obtain the exact Schrödinger wave function big (ψ _n (x,t)big ). For the state n=0, all the expressions found are given in terms of ρ , a c-number quantity satisfying a nonlinear differential equation. For the Caldirola-Kanai system, the entropies do not vary with time, but decrease with increasing damping factor. For the Lane-Emden system, the entropies decrease with increasing time. We also analyze the behavior of the Shannon and Rényi lengths in the charge and magnetic flux spaces and compare them with the respective standard deviations.

  18. The role of the stagnant-film thickness in mesoscopic modeling of equiaxed grain envelopes

    NASA Astrophysics Data System (ADS)

    Souhar, Youssef; De Felice, Valerio F.; Založnik, Miha; Combeau, Hervé; Beckermann, Christoph

    2016-03-01

    The mesoscopic envelope model overcomes the limitations of phase-field methods. It can be applied at larger scales and can include fluid flow at reasonable computing cost. It consists of the description of a dendritic grain by an envelope that links the active dendrite branches. The grain is modelled as an evolving porous medium and the liquid-solid phase change and solute transport are modelled by volume-averaged equations. The velocities of the dendrite tips are determined by the local solute-concentration field in the proximity of the envelope through an analytical stagnant-film model. In this publication, we present our implementation of the model for a binary alloy and we discuss the influence of the stagnant-film thickness, the principal model parameter, on the predicted 3D equiaxed grains by comparisons with the scaling laws for binary-alloy dendrites obtained in recent experiments by Melendez and Beckermann.

  19. Whispering-gallery acoustic sensing: characterization of mesoscopic films and scanning probe microscopy applications.

    PubMed

    La Rosa, Andres H; Li, Nan; Fernandez, Rodolfo; Wang, Xiaohua; Nordstrom, Richard; Padigi, S K

    2011-09-01

    Full understanding of the physics underlying the striking changes in viscoelasticity, relaxation time, and phase transitions that mesoscopic fluid-like films undergo at solid-liquid interfaces, or under confinement between two sliding solid boundaries, constitutes one of the major challenges in condensed matter physics. Their role in the imaging process of solid substrates by scanning probe microscopy (SPM) is also currently controversial. Aiming at improving the reliability and versatility of instrumentation dedicated to characterize mesoscopic films, a noninvasive whispering-gallery acoustic sensing (WGAS) technique is introduced; its application as feedback control in SPM is also demonstrated. To illustrate its working principle and potential merits, WGAS has been integrated into a SPM that uses a sharp tip attached to an electrically driven 32-kHz piezoelectric tuning fork (TF), the latter also tighten to the operating microscope's frame. Such TF-based SPMs typically monitor the TF's state of motion by electrical means, hence subjected to the effects caused by the inherent capacitance of the device (i.e., electrical resonance differing from the probe's mechanical resonance). Instead, the novelty of WGAS resides in exploiting the already existent microscope's frame as an acoustic cavity (its few centimeter-sized perimeter closely matching the operating acoustic wavelength) where standing-waves (generated by the nanometer-sized oscillations of the TF's tines) are sensitively detected by an acoustic transducer (the latter judiciously placed around the microscope's frame perimeter for attaining maximum detection). This way, WGAS is able to remote monitoring, via acoustic means, the nanometer-sized amplitude motion of the TF's tines. (This remote-detection method resembles the ability to hear faint, but still clear, levels of sound at the galleries of a cathedral, despite the extraordinary distance location of the sound source.) In applications aiming at

  20. Reprint of: Four-terminal resistances in mesoscopic networks of metallic wires: Weak localisation and correlations

    NASA Astrophysics Data System (ADS)

    Texier, Christophe; Montambaux, Gilles

    2016-08-01

    We consider the electronic transport in multi-terminal mesoscopic networks of weakly disordered metallic wires. After a brief description of the classical transport, we analyse the weak localisation (WL) correction to the four-terminal resistances, which involves an integration of the Cooperon over the wires with proper weights. We provide an interpretation of these weights in terms of classical transport properties. We illustrate the formalism on examples and show that weak localisation to four-terminal conductances may become large in some situations. In a second part, we study the correlations of four-terminal resistances and show that integration of Diffuson and Cooperon inside the network involves the same weights as the WL. The formulae are applied to multiconnected wire geometries.

  1. Gate-tunable indirect exchange interaction in spin-orbit-coupled mesoscopic rings

    NASA Astrophysics Data System (ADS)

    Nikoofard, H.; Heidari Semiromi, E.

    2015-05-01

    We study the carrier-mediated exchange interaction, the so-called Ruderman-Kittel-Kasuya-Yosida (RKKY) coupling, between two magnetic impurity moments embedded in a semiconductor mesoscopic ring. We treat the ring in the presence of an Aharonov-Bohm-type magnetic flux and the Rashba and Dresselhaus spin-orbit interactions (RSOI and DSOI). Energy eigenvalues of the system are obtained within a tight-binding framework and the strength of the indirect exchange interaction vs. RSOI strengths are plotted for different values of DSOI strength. The results show that the type of the impurity magnetic order, ferromagnetic (F) or antiferromagnetic (AF), depends on the RSOI and DSOI strengths. This leads to a full electrical control on the magnetic alignment of the system through, e.g., an external gate voltage.

  2. 3. QUANTUM DOTS AND WELLS, MESOSCOPIC NETWORKS : Submicron charge-density-wave devices

    NASA Astrophysics Data System (ADS)

    van der Zant, H. J. S.; Markovic, N.; Slot, E.

    2001-10-01

    We review our fabrication methods to produce submicron charge-density-wave (CDW) structures and present measurements of CDW dynamics on a microscopic scale. Our data show that mesoscopic CDW dynamics is different from bulk behavior. We have studied current-conversion and found a size-effect that can not be accounted for by existing models. An explanation might be that the removal and addition of wave fronts becomes correlated in time when probe spacing is reduced below a few µm. On small segments we occasionally observe negative differential resistance in the I(V) characteristics and sometimes the resistance may even become negative. We believe that the interplay between CDW deformations (strain) and quasi-particles may yield non-equilibrium effects that play a crucial role in this new phenomenon. No detailed theoretical calculations are available. Our measurements clearly show the need of a microscopic model for CDW dynamics.

  3. Nonlocal supercurrent in mesoscopic multiterminal SNS Josephson junction in the low-temperature limit

    NASA Astrophysics Data System (ADS)

    Golikova, T. E.; Wolf, M. J.; Beckmann, D.; Batov, I. E.; Bobkova, I. V.; Bobkov, A. M.; Ryazanov, V. V.

    2014-03-01

    A nonlocal supercurrent was observed in mesoscopic planar SNS Josephson junctions with additional normal-metal electrodes, where nonequilibrium quasiparticles were injected from a normal-metal electrode into one of the superconducting banks of the Josephson junction in the absence of a net transport current through the junction. We claim that the observed effect is due to a supercurrent counterflow, appearing to compensate for the quasiparticle flow in the SNS weak link. We have measured the responses of SNS junctions for different distances between the quasiparticle injector and the SNS junction at temperatures far below the superconducting transition temperature. The charge-imbalance relaxation length was estimated by using a modified Kadin, Smith, and Skocpol scheme in the case of a planar geometry. The model developed allows us to describe the interplay of charge imbalance and Josephson effects in the nanoscale proximity system in detail.

  4. Coherent mesoscopic transport through a quantum-dot embedded carbon nanotube ring threaded with magnetic flux

    NASA Astrophysics Data System (ADS)

    Zhao, Hong-Kang; Wang, Jian

    2004-03-01

    We have investigated the coherent mesoscopic transport through a quantum-dot (QD) embedded carbon nanotube ring (CNR) by employing the nonequilibrium Green's function (NGF) technique. The Landauer-Büttiker-like formula is presented to calculate the differential conductance and current-voltage characteristics. Due to the interference of the electrons transporting in the two paths of CNR, the resultant conductivity of electron through the system is determined by the compound concrete structure of CNR-QD system. The tunneling current appears quantum behavior obviously in the small region of source-drain bias. The conductance is adjusted by the gate voltage Vg and the magnetic flux φ. The reversal resonance has been displayed versus the gate voltage, and it is symmetric about Vg for the type I CNR, but it is asymmetric for the type II CNR. The phase inverse oscillations are also presented for the different types of CNRs.

  5. Spectroscopy and thermometry of drumhead modes in a mesoscopic trapped-ion crystal using entanglement.

    PubMed

    Sawyer, Brian C; Britton, Joseph W; Keith, Adam C; Wang, C-C Joseph; Freericks, James K; Uys, Hermann; Biercuk, Michael J; Bollinger, John J

    2012-05-25

    We demonstrate spectroscopy and thermometry of individual motional modes in a mesoscopic 2D ion array using entanglement-induced decoherence as a method of transduction. Our system is a ~400 μm-diameter planar crystal of several hundred 9Be(+) ions exhibiting complex drumhead modes in the confining potential of a Penning trap. Exploiting precise control over the 9Be(+) valence electron spins, we apply a homogeneous spin-dependent optical dipole force to excite arbitrary transverse modes with an effective wavelength approaching the interparticle spacing (~20 μm). Center-of-mass displacements below 1 nm are detected via the entanglement of spin and motional degrees of freedom. PMID:23003249

  6. Spectroscopy and Thermometry of Drumhead Modes in a Mesoscopic Trapped-Ion Crystal Using Entanglement

    NASA Astrophysics Data System (ADS)

    Sawyer, Brian C.; Britton, Joseph W.; Keith, Adam C.; Wang, C.-C. Joseph; Freericks, James K.; Uys, Hermann; Biercuk, Michael J.; Bollinger, John J.

    2012-05-01

    We demonstrate spectroscopy and thermometry of individual motional modes in a mesoscopic 2D ion array using entanglement-induced decoherence as a method of transduction. Our system is a ˜400μm-diameter planar crystal of several hundred Be+9 ions exhibiting complex drumhead modes in the confining potential of a Penning trap. Exploiting precise control over the Be+9 valence electron spins, we apply a homogeneous spin-dependent optical dipole force to excite arbitrary transverse modes with an effective wavelength approaching the interparticle spacing (˜20μm). Center-of-mass displacements below 1 nm are detected via the entanglement of spin and motional degrees of freedom.

  7. Ballistic thermal rectification in asymmetric three-terminal mesoscopic dielectric systems

    NASA Astrophysics Data System (ADS)

    Ming, Yi; Xian Wang, Zhe; Ding, Ze Jun; Li, Hui Min

    2010-10-01

    By coupling a temperature probe to the asymmetric three-terminal mesoscopic dielectric system, ballistic thermal rectification at low temperature is analytically studied based on the Landauer formulation of transport theory. It is seen that thermal rectification is a purely quantum effect and the quantum statistics of phonons in thermal reservoirs is necessary. Moreover, when the phonon re-emits into the system from the temperature probe, energy changing is necessary to realize thermal rectification. Another necessary condition is the different asymmetries for phonons with different frequencies, which is reflected by the dependence of the ratio τRC(ω)/τRL(ω) on ω, the phonon's frequency, where τRC(ω) and τRL(ω) are respectively the transmission coefficients from two asymmetric terminals to the temperature probe. The analytical results are confirmed by extensive numerical simulations.

  8. Thermoelectric transport of mesoscopic conductors coupled to voltage and thermal probes

    NASA Astrophysics Data System (ADS)

    Sánchez, David; Serra, Llorenç

    2011-11-01

    We investigate the basic properties of the thermopower (Seebeck coefficient) of phase-coherent conductors under the influence of dephasing and inelastic processes. Transport across the system is caused by a voltage bias or a thermal gradient applied between two terminals. Inelastic scattering is modeled with the aid of an additional probe acting as an ideal potentiometer and thermometer. We find that inelastic scattering reduces the conductor's thermopower and, more unexpectedly, generates a magnetic field asymmetry in the Seebeck coefficient. The latter effect is shown to be a higher-order effect in the Sommerfeld expansion. We discuss our result by using two illustrative examples. First, we consider a generic mesoscopic system described within random matrix theory and demonstrate that thermopower fluctuations disappear quickly as the number of probe modes increases. Second, the asymmetry is explicitly calculated in the quantum limit of a ballistic microjunction. We find that asymmetric scattering strongly enhances the effect and discuss its dependence on temperature and Fermi energy.

  9. Generic mesoscopic neural networks based on statistical mechanics of neocortical interactions

    NASA Astrophysics Data System (ADS)

    Ingber, Lester

    1992-02-01

    A series of papers has developed a statistical mechanics of neocortical interactions (SMNI), deriving aggregate behavior of experimentally observed columns of neurons from statistical electrical-chemical properties of synaptic interactions, demonstrating its capability in describing large-scale properties of short-term memory and electroencephalographic systematics. This methodology also defines an algorithm to construct a mesoscopic neural network, based on realistic neocortical processes and parameters, to record patterns of brain activity and to compute the evolution of this system. Furthermore, this algorithm is quite generic and can be used to similarly process information in other systems, especially, but not limited to, those amenable to modeling by mathematical physics techniques alternatively described by path-integral Lagrangians, Fokker-Planck equations, or Langevin rate equations. This methodology is made possible and practical by a confluence of techniques drawn from SMNI itself, modern methods of functional stochastic calculus defining nonlinear Lagrangians, very fast simulated reannealing, and parallel-processing computation.

  10. Mesoscopic modeling of liquid water transport in polymer electrolyte fuel cells

    SciTech Connect

    Mukherjee, Partha P; Wang, Chao Yang

    2008-01-01

    A key performance limitation in polymer electrolyte fuel cells (PEFC), manifested in terms of mass transport loss, originates from liquid water transport and resulting flooding phenomena in the constituent components. Liquid water leads to the coverage of the electrochemically active sites in the catalyst layer (CL) rendering reduced catalytic activity and blockage of the available pore space in the porous CL and fibrous gas diffusion layer (GDL) resulting in hindered oxygen transport to the active reaction sites. The cathode CL and the GDL therefore playa major role in the mass transport loss and hence in the water management of a PEFC. In this article, we present the development of a mesoscopic modeling formalism coupled with realistic microstructural delineation to study the profound influence of the pore structure and surface wettability on liquid water transport and interfacial dynamics in the PEFC catalyst layer and gas diffusion layer.

  11. Stochastic Bistability and Bifurcation in a Mesoscopic Signaling System with Autocatalytic Kinase

    PubMed Central

    Bishop, Lisa M.; Qian, Hong

    2010-01-01

    Abstract Bistability is a nonlinear phenomenon widely observed in nature including in biochemical reaction networks. Deterministic chemical kinetics studied in the past has shown that bistability occurs in systems with strong (cubic) nonlinearity. For certain mesoscopic, weakly nonlinear (quadratic) biochemical reaction systems in a small volume, however, stochasticity can induce bistability and bifurcation that have no macroscopic counterpart. We report the simplest yet known reactions involving driven phosphorylation-dephosphorylation cycle kinetics with autocatalytic kinase. We show that the noise-induced phenomenon is correlated with free energy dissipation and thus conforms with the open-chemical system theory. A previous reported noise-induced bistability in futile cycles is found to have originated from the kinase synchronization in a bistable system with slow transitions, as reported here. PMID:20074511

  12. Vortex patterns in a mesoscopic superconducting rod with a magnetic dot

    NASA Astrophysics Data System (ADS)

    Doria, Mauro M.; de C. Romaguera, Antonio R.; Peeters, F. M.

    2010-03-01

    We study a mesoscopic superconducting rod with a magnetic dot on its top having its moment oriented along the axis of symmetry. We study the dependence of the vortex pattern with the height and find that for very short and very long rods, the vortex pattern acquires a simple structure, consisting of giant and of multivortex states, respectively. In the long limit, the most stable configuration consists of two vortices, that reach the lateral surface of the rod diametrically opposed. The long rod shows reentrant behavior within some range of its radius and of the dot’s magnetic moment. Our results are obtained within the Ginzburg-Landau approach in the limit of no magnetic shielding.

  13. Using Brownian motion to measure shape asymmetry in mesoscopic matter using optical tweezers.

    PubMed

    Roy, Basudev; Mondal, Argha; Bera, Sudipta K; Banerjee, Ayan

    2016-06-21

    We propose a new method for quantifying shape asymmetry on the mesoscopic scale. The method takes advantage of the intrinsic coupling between rotational and translational Brownian motion (RBM and TBM, respectively) which happens in the case of asymmetric particles. We determine the coupling by measuring different correlation functions of the RBM and TBM for single, morphologically different, weakly trapped red blood cells in optical tweezers. The cells have different degrees of asymmetry that are controllably produced by varying the hypertonicity of their aqueous environment. We demonstrate a clear difference in the nature of the correlation functions both qualitatively and quantitatively for three types of cells having a varying degree of asymmetry. This method can have a variety of applications ranging from early stage disease diagnosis to quality control in microfabrication. PMID:27198612

  14. Bohm-Aharonov and Kondo effects on tunneling currents in a mesoscopic ring

    SciTech Connect

    Davidovich, M.A.; Anda, E.V.; Chiappe, G.

    1997-03-01

    We present an analysis of the Kondo effect on the Bohm-Aharonov oscillations of the tunneling currents in a mesoscopic ring with a quantum dot inserted in one of its arms. The system is described by an Anderson-impurity tight-binding Hamiltonian where the electron-electron interaction is restricted to the dot. The currents are obtained using nonequilibrium Green functions calculated through a cumulant diagrammatic expansion in the chain approximation. It is shown that at low temperature, even with the system out of resonance, the Kondo peak provides a channel for the electron to tunnel through the dot, giving rise to the Bohm-Aharonov oscillations of the current. At high temperature these oscillations are important only if the dot level is aligned to the Fermi level, when the resonance condition is satisfied. {copyright} {ital 1997} {ital The American Physical Society}

  15. Whispering-gallery acoustic sensing: Characterization of mesoscopic films and scanning probe microscopy applications

    NASA Astrophysics Data System (ADS)

    La Rosa, Andres H.; Li, Nan; Fernandez, Rodolfo; Wang, Xiaohua; Nordstrom, Richard; Padigi, S. K.

    2011-09-01

    Full understanding of the physics underlying the striking changes in viscoelasticity, relaxation time, and phase transitions that mesoscopic fluid-like films undergo at solid-liquid interfaces, or under confinement between two sliding solid boundaries, constitutes one of the major challenges in condensed matter physics. Their role in the imaging process of solid substrates by scanning probe microscopy (SPM) is also currently controversial. Aiming at improving the reliability and versatility of instrumentation dedicated to characterize mesoscopic films, a noninvasive whispering-gallery acoustic sensing (WGAS) technique is introduced; its application as feedback control in SPM is also demonstrated. To illustrate its working principle and potential merits, WGAS has been integrated into a SPM that uses a sharp tip attached to an electrically driven 32-kHz piezoelectric tuning fork (TF), the latter also tighten to the operating microscope's frame. Such TF-based SPMs typically monitor the TF's state of motion by electrical means, hence subjected to the effects caused by the inherent capacitance of the device (i.e., electrical resonance differing from the probe's mechanical resonance). Instead, the novelty of WGAS resides in exploiting the already existent microscope's frame as an acoustic cavity (its few centimeter-sized perimeter closely matching the operating acoustic wavelength) where standing-waves (generated by the nanometer-sized oscillations of the TF's tines) are sensitively detected by an acoustic transducer (the latter judiciously placed around the microscope's frame perimeter for attaining maximum detection). This way, WGAS is able to remote monitoring, via acoustic means, the nanometer-sized amplitude motion of the TF's tines. (This remote-detection method resembles the ability to hear faint, but still clear, levels of sound at the galleries of a cathedral, despite the extraordinary distance location of the sound source.) In applications aiming at

  16. Mesoscopic model parametrization of hydrogen bonds and stacking interactions of RNA from melting temperatures

    PubMed Central

    Weber, Gerald

    2013-01-01

    Information about molecular interactions in DNA can be obtained from experimental melting temperature data by using mesoscopic statistical physics models. Here, we extend the technique to RNA and show that the new parameters correctly reproduce known properties such as the stronger hydrogen bonds of AU base pairs. We also were able to calculate a complete set of elastic constants for all 10 irreducible combinations of nearest neighbours (NNs). We believe that this is particularly useful as experimentally derived information about RNA elasticity is relatively scarce. The melting temperature prediction using the present model improves over those from traditional NN model, providing thus an alternative way to calculate these temperatures for RNA. Additionally, we calculated the site-dependent base pair oscillation to explain why RNA shows larger oscillation amplitudes despite having stronger AU hydrogen bonds. PMID:23087379

  17. Superposition and entanglement of mesoscopic squeezed vacuum states in cavity QED

    SciTech Connect

    Chen Changyong; Feng Mang; Gao Kelin

    2006-03-15

    We propose a scheme to generate superposition and entanglement between the mesoscopic squeezed vacuum states by considering the two-photon interaction of N two-level atoms in a cavity with high quality factor, assisted by a strong driving field. By virtue of specific choices of the cavity detuning, a number of multiparty entangled states can be prepared, including the entanglement between the atomic and the squeezed vacuum cavity states and between the squeezed vacuum states and the coherent states of the cavities. We also present how to prepare entangled states and 'Schroedinger cats' states regarding the squeezed vacuum states of the cavity modes. The possible extension and application of our scheme are discussed. Our scheme is close to the reach with current cavity QED techniques.

  18. Studying brain functions with mesoscopic measurements: advances in electrocorticography for non-human primates

    PubMed Central

    Fukushima, Makoto; Chao, Zenas C.

    2015-01-01

    Our brain is organized in a modular structure. Information in different modalities is processed within distinct cortical areas. However, individual cortical areas cannot enable complex cognitive functions without interacting with other cortical areas. Electrocorticography (ECoG) has recently become an important tool for studying global network activity across cortical areas in animal models. With stable recordings of electrical field potentials from multiple cortical areas, ECoG provides an opportunity to systematically study large-scale cortical activity at a mesoscopic spatiotemporal resolution under various experimental conditions. Recent developments in thin, flexible ECoG electrodes permit recording field potentials from not only gyral but intrasulcal cortical surfaces. Our review here focuses on the recent advances of ECoG applications to non-human primates. PMID:25889531

  19. Testing for HIV

    MedlinePlus

    ... Medical Devices Radiation-Emitting Products Vaccines, Blood & Biologics Animal & Veterinary Cosmetics Tobacco Products Vaccines, Blood & Biologics Home Vaccines, Blood & Biologics Safety & Availability (Biologics) HIV Home Test Kits Testing for HIV Share Tweet Linkedin Pin it More ...

  20. Phase Competition and Magnetotransport Phenomena in Manganite Films and Mesoscopic Structures

    NASA Astrophysics Data System (ADS)

    Wu, Tom

    2006-03-01

    The importance of competition between ferromagnetic metallic (FMM) and charge-ordered insulating (COI) phases in the physics of bulk manganites has been established through a wide variety of techniques. One exotic consequence of this phase competition is step-like features in magnetotransport observed in bulk and single-crystals of Pr0.65(CaySr1-y)0.35MnO3 (PCSMO) with 0.7<=y<=0.8. The length-scale of the phase coexistence is ˜1 micron, motivating a study of structures with dimensions similar to this natural length scale where phenomenology distinct from that of bulk counterparts is expected. Toward that end, we have synthesized films and laterally confined mesoscopic bridges of PCSMO and studied their magnetotransport properties. In particular, we observed: (1) Intrinsic ultrasharp magnetization steps below 5 K in both bulk and film samples and their dependence on the extrinsic measurement protocols; (2) Spontaneous jumps of resistance during both the ramping of magnetic field and the relaxation after the field cycle; (3) I-V curves exhibiting negative differential resistance (NDR) in certain ranges of temperature and magnetic field. All of these phenomena can be explained in the context of interconversion between the COI phase and the FMM phase. As expected, this interconversion can be triggered by external magnetic field, as found in the case of the magnetization and resistance steps. Alternatively, in the mesoscopic structures with dimensions similar to the size of the competing FMM and COI domains, a local Joule heating-induced annihilation of conducting filaments causes the anomalous NDR.