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. 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.

  8. 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.

  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. 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…

  14. 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.

  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

    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

  19. 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.

  20. 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

  1. 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.

  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

    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.

  5. 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

  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. 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

  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. 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

  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 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.

  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 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.

  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 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

  5. 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.

  6. 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.

  7. 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.

  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. 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 ...

  13. 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

  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. 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.

  8. 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

  9. 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.

  10. 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.

  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. 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…

  17. 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

  18. 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",…

  19. 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…

  20. 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...

  1. 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...

  2. 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...

  3. 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…

  4. 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…

  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. 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.

  11. 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.

  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. 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

  12. 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.

  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. 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.

  19. 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.

  20. 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.

  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. 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

  7. [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

  8. 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.

  9. 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

  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. 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.

  17. 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

  18. 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

  19. 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.

  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 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.

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  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. 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

  20. 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

  1. 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.

  2. 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

  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. 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.

  5. 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.

  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. 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

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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

  1. 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

  2. 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

  3. 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

  4. 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.

  5. 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.

  6. 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

  7. 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

  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. 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

  15. 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.

  16. 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

  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. 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.

  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. 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.

  9. 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

  10. 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