Sample records for obtencao das constantes

  1. A Wind-Forced Modeling Study of the Canary Current System from 30 Degrees N to 42.5 Degrees N

    DTIC Science & Technology

    1998-06-01

    and Haynes and Barton (1990), using high resolution infra-red images from NOAA7 and NOAA9 and numerous in- situ measurements, reveal the existence of...dinamica das Aguas costeiras de Portugal. Dissertacao apresentada a Universidade de Lisboa para obtencao do grau de Doutor em Fisica, especializacao

  2. Wind-Forced Modeling Studies of Currents, Meanders, Eddies, and Filaments of the Canary Current System

    DTIC Science & Technology

    1997-06-01

    infra-red images from NOAA7 and NOAA9 and numerous in- situ measurements reveal the existence of a surface poleward flow off the northern coast of...dinamica das Aguas costeiras de Portugal. Dissertacao apresentada a Universidade de Lisboa para obtencao do grau de Doutor em Fisica, especializacao

  3. easyDAS: Automatic creation of DAS servers

    PubMed Central

    2011-01-01

    Background The Distributed Annotation System (DAS) has proven to be a successful way to publish and share biological data. Although there are more than 750 active registered servers from around 50 organizations, setting up a DAS server comprises a fair amount of work, making it difficult for many research groups to share their biological annotations. Given the clear advantage that the generalized sharing of relevant biological data is for the research community it would be desirable to facilitate the sharing process. Results Here we present easyDAS, a web-based system enabling anyone to publish biological annotations with just some clicks. The system, available at http://www.ebi.ac.uk/panda-srv/easydas is capable of reading different standard data file formats, process the data and create a new publicly available DAS source in a completely automated way. The created sources are hosted on the EBI systems and can take advantage of its high storage capacity and network connection, freeing the data provider from any network management work. easyDAS is an open source project under the GNU LGPL license. Conclusions easyDAS is an automated DAS source creation system which can help many researchers in sharing their biological data, potentially increasing the amount of relevant biological data available to the scientific community. PMID:21244646

  4. MyDas, an Extensible Java DAS Server

    PubMed Central

    Jimenez, Rafael C.; Quinn, Antony F.; Jenkinson, Andrew M.; Mulder, Nicola; Martin, Maria; Hunter, Sarah; Hermjakob, Henning

    2012-01-01

    A large number of diverse, complex, and distributed data resources are currently available in the Bioinformatics domain. The pace of discovery and the diversity of information means that centralised reference databases like UniProt and Ensembl cannot integrate all potentially relevant information sources. From a user perspective however, centralised access to all relevant information concerning a specific query is essential. The Distributed Annotation System (DAS) defines a communication protocol to exchange annotations on genomic and protein sequences; this standardisation enables clients to retrieve data from a myriad of sources, thus offering centralised access to end-users. We introduce MyDas, a web server that facilitates the publishing of biological annotations according to the DAS specification. It deals with the common functionality requirements of making data available, while also providing an extension mechanism in order to implement the specifics of data store interaction. MyDas allows the user to define where the required information is located along with its structure, and is then responsible for the communication protocol details. PMID:23028496

  5. MyDas, an extensible Java DAS server.

    PubMed

    Salazar, Gustavo A; García, Leyla J; Jones, Philip; Jimenez, Rafael C; Quinn, Antony F; Jenkinson, Andrew M; Mulder, Nicola; Martin, Maria; Hunter, Sarah; Hermjakob, Henning

    2012-01-01

    A large number of diverse, complex, and distributed data resources are currently available in the Bioinformatics domain. The pace of discovery and the diversity of information means that centralised reference databases like UniProt and Ensembl cannot integrate all potentially relevant information sources. From a user perspective however, centralised access to all relevant information concerning a specific query is essential. The Distributed Annotation System (DAS) defines a communication protocol to exchange annotations on genomic and protein sequences; this standardisation enables clients to retrieve data from a myriad of sources, thus offering centralised access to end-users.We introduce MyDas, a web server that facilitates the publishing of biological annotations according to the DAS specification. It deals with the common functionality requirements of making data available, while also providing an extension mechanism in order to implement the specifics of data store interaction. MyDas allows the user to define where the required information is located along with its structure, and is then responsible for the communication protocol details.

  6. Estimation of rate constants of PCB dechlorination reactions using an anaerobic dehalogenation model.

    PubMed

    Karakas, Filiz; Imamoglu, Ipek

    2017-02-15

    This study aims to estimate anaerobic dechlorination rate constants (k m ) of reactions of individual PCB congeners using data from four laboratory microcosms set up using sediment from Baltimore Harbor. Pathway k m values are estimated by modifying a previously developed model as Anaerobic Dehalogenation Model (ADM) which can be applied to any halogenated hydrophobic organic (HOC). Improvements such as handling multiple dechlorination activities (DAs) and co-elution of congeners, incorporating constraints, using new goodness of fit evaluation led to an increase in accuracy, speed and flexibility of ADM. DAs published in the literature in terms of chlorine substitutions as well as specific microorganisms and their combinations are used for identification of pathways. The best fit explaining the congener pattern changes was found for pathways of Phylotype DEH10, which has the ability to remove doubly flanked chlorines in meta and para positions, para flanked chlorines in meta position. The range of estimated k m values is between 0.0001-0.133d -1 , the median of which is found to be comparable to the few available published biologically confirmed rate constants. Compound specific modelling studies such as that performed by ADM can enable monitoring and prediction of concentration changes as well as toxicity during bioremediation. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Elongational flow of polymer melts at constant strain rate, constant stress and constant force

    NASA Astrophysics Data System (ADS)

    Wagner, Manfred H.; Rolón-Garrido, Víctor H.

    2013-04-01

    Characterization of polymer melts in elongational flow is typically performed at constant elongational rate or rarely at constant tensile stress conditions. One of the disadvantages of these deformation modes is that they are hampered by the onset of "necking" instabilities according to the Considère criterion. Experiments at constant tensile force have been performed even more rarely, in spite of the fact that this deformation mode is free from necking instabilities and is of considerable industrial relevance as it is the correct analogue of steady fiber spinning. It is the objective of the present contribution to present for the first time a full experimental characterization of a long-chain branched polyethylene melt in elongational flow. Experiments were performed at constant elongation rate, constant tensile stress and constant tensile force by use of a Sentmanat Extensional Rheometer (SER) in combination with an Anton Paar MCR301 rotational rheometer. The accessible experimental window and experimental limitations are discussed. The experimental data are modelled by using the Wagner I model. Predictions of the steady-start elongational viscosity in constant strain rate and creep experiments are found to be identical, albeit only by extrapolation of the experimental data to Hencky strains of the order of 6. For constant stress experiments, a minimum in the strain rate and a corresponding maximum in the elongational viscosity is found at a Hencky strain of the order of 3, which, although larger than the steady-state value, follows roughly the general trend of the steady-state elongational viscosity. The constitutive analysis also reveals that constant tensile force experiments indicate a larger strain hardening potential than seen in constant elongation rate or constant tensile stress experiments. This may be indicative of the effect of necking under constant elongation rate or constant tensile stress conditions according to the Considère criterion.

  8. Constants and pseudo-constants of the Kadomtsev-Petviashvili equation.

    PubMed

    Case, K M

    1985-08-01

    Elucidating earlier work, it is shown that the Kadomtsev-Petviashvili equation has n + 2 constants for all n >/= 0. It also has a pseudo-constant from which the constants can be obtained by differentiation with respect to time. The pseudo-constant can be obtained from a basis functional J(n) ((n+2)) = -1/18 [unk] y(n+2)q by taking repeated Poisson brackets with the Hamiltonian.

  9. Constants and pseudo-constants of the Kadomtsev-Petviashvili equation

    PubMed Central

    Case, K. M.

    1985-01-01

    Elucidating earlier work, it is shown that the Kadomtsev-Petviashvili equation has n + 2 constants for all n ≥ 0. It also has a pseudo-constant from which the constants can be obtained by differentiation with respect to time. The pseudo-constant can be obtained from a basis functional Jn(n+2) = -1/18 [unk] yn+2q by taking repeated Poisson brackets with the Hamiltonian. PMID:16593588

  10. Constants and pseudo-constants of the Kadomtsev-Petviashvili equation

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

    Case, K.M.

    1985-08-01

    Elucidating earlier work, it is shown that the Kadomtsev-Petviashvili equation has n + 2 constants for all n greater than or equal to 0. It also has a pseudo-constant from which the constants can be obtained by differentiation with respect to time. The pseudo-constant can be obtained from a basis functional J/sub n/sup (n+2)/ = -1/18 integral y/sup n+2/ q by taking repeated Poisson brackets with the Hamiltonian.

  11. "Das Konkrete ist das Abstrakte, an das man sich schließlich gewöhnt hat." (Laurent Schwartz) Über den Ablauf des mathematischen Verstehens

    NASA Astrophysics Data System (ADS)

    Lowsky, Martin

    Die im Titel genannte Aussage findet sich in den Lebenserinnerungen von Laurent Schwartz (1915-2002), einem der fruchtbarsten Mathematiker, Mitglied der Gruppe Bourbaki. Im Original lautet die Aussage: "un objet concret est un objet abstrait auquel on a fini par s'habituer." Schwartz erläutert sie am Beispiel des Integrals über {e^{-1/2{x^2}}} , das den Wert Wurzel aus 2π hat und in dem sich also die Zahlen e und π verknüpfen. Was Schwartz aber vor allem ausdrücken will, ist dies: Das mathematische Verständnisd geht langsam vor sich und es bedarf der Anstrengung. "Es ist eine Frage der Zeit und der Energie", sagt Schwartz, und gerade dies mache es so schwer, die höhere Mathematik unter das Volk zu bringen. Das Lernen und Lehren von Mathematik laufe eben mühevoll und langsam ab.

  12. Integrating sequence and structural biology with DAS

    PubMed Central

    Prlić, Andreas; Down, Thomas A; Kulesha, Eugene; Finn, Robert D; Kähäri, Andreas; Hubbard, Tim JP

    2007-01-01

    Background The Distributed Annotation System (DAS) is a network protocol for exchanging biological data. It is frequently used to share annotations of genomes and protein sequence. Results Here we present several extensions to the current DAS 1.5 protocol. These provide new commands to share alignments, three dimensional molecular structure data, add the possibility for registration and discovery of DAS servers, and provide a convention how to provide different types of data plots. We present examples of web sites and applications that use the new extensions. We operate a public registry of DAS sources, which now includes entries for more than 250 distinct sources. Conclusion Our DAS extensions are essential for the management of the growing number of services and exchange of diverse biological data sets. In addition the extensions allow new types of applications to be developed and scientific questions to be addressed. The registry of DAS sources is available at PMID:17850653

  13. DASMiner: discovering and integrating data from DAS sources

    PubMed Central

    2009-01-01

    Background DAS is a widely adopted protocol for providing syntactic interoperability among biological databases. The popularity of DAS is due to a simplified and elegant mechanism for data exchange that consists of sources exposing their RESTful interfaces for data access. As a growing number of DAS services are available for molecular biology resources, there is an incentive to explore this protocol in order to advance data discovery and integration among these resources. Results We developed DASMiner, a Matlab toolkit for querying DAS data sources that enables creation of integrated biological models using the information available in DAS-compliant repositories. DASMiner is composed by a browser application and an API that work together to facilitate gathering of data from different DAS sources, which can be used for creating enriched datasets from multiple sources. The browser is used to formulate queries and navigate data contained in DAS sources. Users can execute queries against these sources in an intuitive fashion, without the need of knowing the specific DAS syntax for the particular source. Using the source's metadata provided by the DAS Registry, the browser's layout adapts to expose only the set of commands and coordinate systems supported by the specific source. For this reason, the browser can interrogate any DAS source, independently of the type of data being served. The API component of DASMiner may be used for programmatic access of DAS sources by programs in Matlab. Once the desired data is found during navigation, the query is exported in the format of an API call to be used within any Matlab application. We illustrate the use of DASMiner by creating integrative models of histone modification maps and protein-protein interaction networks. These enriched datasets were built by retrieving and integrating distributed genomic and proteomic DAS sources using the API. Conclusion The support of the DAS protocol allows that hundreds of molecular biology

  14. Connecting the Dots in DAS

    ERIC Educational Resources Information Center

    Ford, Tracy

    2012-01-01

    Many institutions implement a distributed antenna system (DAS) as part of a holistic approach to providing better wireless coverage and capacity on campus. A DAS provides wireless service within a particular area or structure via a network of separate antenna nodes that are connected to a common source through fiber or coaxial cable. Because DAS…

  15. Constant fields and constant gradients in open ionic channels.

    PubMed Central

    Chen, D P; Barcilon, V; Eisenberg, R S

    1992-01-01

    Ions enter cells through pores in proteins that are holes in dielectrics. The energy of interaction between ion and charge induced on the dielectric is many kT, and so the dielectric properties of channel and pore are important. We describe ionic movement by (three-dimensional) Nemst-Planck equations (including flux and net charge). Potential is described by Poisson's equation in the pore and Laplace's equation in the channel wall, allowing induced but not permanent charge. Asymptotic expansions are constructed exploiting the long narrow shape of the pore and the relatively high dielectric constant of the pore's contents. The resulting one-dimensional equations can be integrated numerically; they can be analyzed when channels are short or long (compared with the Debye length). Traditional constant field equations are derived if the induced charge is small, e.g., if the channel is short or if the total concentration gradient is zero. A constant gradient of concentration is derived if the channel is long. Plots directly comparable to experiments are given of current vs voltage, reversal potential vs. concentration, and slope conductance vs. concentration. This dielectric theory can easily be tested: its parameters can be determined by traditional constant field measurements. The dielectric theory then predicts current-voltage relations quite different from constant field, usually more linear, when gradients of total concentration are imposed. Numerical analysis shows that the interaction of ion and channel can be described by a mean potential if, but only if, the induced charge is negligible, that is to say, the electric field is spatially constant. Images FIGURE 1 PMID:1376159

  16. New Quasar Studies Keep Fundamental Physical Constant Constant

    NASA Astrophysics Data System (ADS)

    2004-03-01

    Very Large Telescope sets stringent limit on possible variation of the fine-structure constant over cosmological time Summary Detecting or constraining the possible time variations of fundamental physical constants is an important step toward a complete understanding of basic physics and hence the world in which we live. A step in which astrophysics proves most useful. Previous astronomical measurements of the fine structure constant - the dimensionless number that determines the strength of interactions between charged particles and electromagnetic fields - suggested that this particular constant is increasing very slightly with time. If confirmed, this would have very profound implications for our understanding of fundamental physics. New studies, conducted using the UVES spectrograph on Kueyen, one of the 8.2-m telescopes of ESO's Very Large Telescope array at Paranal (Chile), secured new data with unprecedented quality. These data, combined with a very careful analysis, have provided the strongest astronomical constraints to date on the possible variation of the fine structure constant. They show that, contrary to previous claims, no evidence exist for assuming a time variation of this fundamental constant. PR Photo 07/04: Relative Changes with Redshift of the Fine Structure Constant (VLT/UVES) A fine constant To explain the Universe and to represent it mathematically, scientists rely on so-called fundamental constants or fixed numbers. The fundamental laws of physics, as we presently understand them, depend on about 25 such constants. Well-known examples are the gravitational constant, which defines the strength of the force acting between two bodies, such as the Earth and the Moon, and the speed of light. One of these constants is the so-called "fine structure constant", alpha = 1/137.03599958, a combination of electrical charge of the electron, the Planck constant and the speed of light. The fine structure constant describes how electromagnetic forces hold

  17. Inflation with a smooth constant-roll to constant-roll era transition

    NASA Astrophysics Data System (ADS)

    Odintsov, S. D.; Oikonomou, V. K.

    2017-07-01

    In this paper, we study canonical scalar field models, with a varying second slow-roll parameter, that allow transitions between constant-roll eras. In the models with two constant-roll eras, it is possible to avoid fine-tunings in the initial conditions of the scalar field. We mainly focus on the stability of the resulting solutions, and we also investigate if these solutions are attractors of the cosmological system. We shall calculate the resulting scalar potential and, by using a numerical approach, we examine the stability and attractor properties of the solutions. As we show, the first constant-roll era is dynamically unstable towards linear perturbations, and the cosmological system is driven by the attractor solution to the final constant-roll era. As we demonstrate, it is possible to have a nearly scale-invariant power spectrum of primordial curvature perturbations in some cases; however, this is strongly model dependent and depends on the rate of the final constant-roll era. Finally, we present, in brief, the essential features of a model that allows oscillations between constant-roll eras.

  18. The hubble constant.

    PubMed

    Huchra, J P

    1992-04-17

    The Hubble constant is the constant of proportionality between recession velocity and distance in the expanding universe. It is a fundamental property of cosmology that sets both the scale and the expansion age of the universe. It is determined by measurement of galaxy The Hubble constant is the constant of proportionality between recession velocity and development of new techniques for the measurements of galaxy distances, both calibration uncertainties and debates over systematic errors remain. Current determinations still range over nearly a factor of 2; the higher values favored by most local measurements are not consistent with many theories of the origin of large-scale structure and stellar evolution.

  19. Processing Approaches for DAS-Enabled Continuous Seismic Monitoring

    NASA Astrophysics Data System (ADS)

    Dou, S.; Wood, T.; Freifeld, B. M.; Robertson, M.; McDonald, S.; Pevzner, R.; Lindsey, N.; Gelvin, A.; Saari, S.; Morales, A.; Ekblaw, I.; Wagner, A. M.; Ulrich, C.; Daley, T. M.; Ajo Franklin, J. B.

    2017-12-01

    Distributed Acoustic Sensing (DAS) is creating a "field as laboratory" capability for seismic monitoring of subsurface changes. By providing unprecedented spatial and temporal sampling at a relatively low cost, DAS enables field-scale seismic monitoring to have durations and temporal resolutions that are comparable to those of laboratory experiments. Here we report on seismic processing approaches developed during data analyses of three case studies all using DAS-enabled seismic monitoring with applications ranging from shallow permafrost to deep reservoirs: (1) 10-hour downhole monitoring of cement curing at Otway, Australia; (2) 2-month surface monitoring of controlled permafrost thaw at Fairbanks, Alaska; (3) multi-month downhole and surface monitoring of carbon sequestration at Decatur, Illinois. We emphasize the data management and processing components relevant to DAS-based seismic monitoring, which include scalable approaches to data management, pre-processing, denoising, filtering, and wavefield decomposition. DAS has dramatically increased the data volume to the extent that terabyte-per-day data loads are now typical, straining conventional approaches to data storage and processing. To achieve more efficient use of disk space and network bandwidth, we explore improved file structures and data compression schemes. Because noise floor of DAS measurements is higher than that of conventional sensors, optimal processing workflow involving advanced denoising, deconvolution (of the source signatures), and stacking approaches are being established to maximize signal content of DAS data. The resulting workflow of data management and processing could accelerate the broader adaption of DAS for continuous monitoring of critical processes.

  20. Data Acquisition System(DAS) Sustaining Engineering

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This paper presents general information describing the Data Acquisition System contract, a summary of objectives, tasks performed and completed. The hardware deliverables which are comprised of: 1) Two ground DAS units; 2) Two flight DAS units; 3) Logistic spares; and 4) Shipping containers are described. Also included are the data requirements and scope of the contract.

  1. Constant load and constant volume response of municipal solid waste in simple shear.

    PubMed

    Zekkos, Dimitrios; Fei, Xunchang

    2017-05-01

    Constant load and constant volume simple shear testing was conducted on relatively fresh municipal solid waste (MSW) from two landfills in the United States, one in Michigan and a second in Texas, at respective natural moisture content below field capacity. The results were assessed in terms of two failure strain criteria, at 10% and 30% shear strain, and two interpretations of effective friction angle. Overall, friction angle obtained assuming that the failure plane is horizontal and at 10% shear strain resulted in a conservative estimation of shear strength of MSW. Comparisons between constant volume and constant load simple shear testing results indicated significant differences in the shear response of MSW with the shear resistance in constant volume being lower than the shear resistance in constant load. The majority of specimens were nearly uncompacted during specimen preparation to reproduce the state of MSW in bioreactor landfills or in uncontrolled waste dumps. The specimens had identical percentage of <20mm material but the type of <20mm material was different. The <20mm fraction from Texas was finer and of high plasticity. MSW from Texas was overall weaker in both constant load and constant volume conditions compared to Michigan waste. The results of these tests suggest the possibility of significantly lower shear strength of MSW in bioreactor landfills where waste is placed with low compaction effort and constant volume, i.e., "undrained", conditions may occur. Compacted MSW specimens resulted in shear strength parameters that are higher than uncompacted specimens and closer to values reported in the literature. However, the normalized undrained shear strength in simple shear for uncompacted and compacted MSW was still higher than the normalized undrained shear strength reported in the literature for clayey and silty soils. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. (In)validity of the constant field and constant currents assumptions in theories of ion transport.

    PubMed Central

    Syganow, A; von Kitzing, E

    1999-01-01

    Constant electric fields and constant ion currents are often considered in theories of ion transport. Therefore, it is important to understand the validity of these helpful concepts. The constant field assumption requires that the charge density of permeant ions and flexible polar groups is virtually voltage independent. We present analytic relations that indicate the conditions under which the constant field approximation applies. Barrier models are frequently fitted to experimental current-voltage curves to describe ion transport. These models are based on three fundamental characteristics: a constant electric field, negligible concerted motions of ions inside the channel (an ion can enter only an empty site), and concentration-independent energy profiles. An analysis of those fundamental assumptions of barrier models shows that those approximations require large barriers because the electrostatic interaction is strong and has a long range. In the constant currents assumption, the current of each permeating ion species is considered to be constant throughout the channel; thus ion pairing is explicitly ignored. In inhomogeneous steady-state systems, the association rate constant determines the strength of ion pairing. Among permeable ions, however, the ion association rate constants are not small, according to modern diffusion-limited reaction rate theories. A mathematical formulation of a constant currents condition indicates that ion pairing very likely has an effect but does not dominate ion transport. PMID:9929480

  3. Cosmological constant and quantum gravitational corrections to the running fine structure constant.

    PubMed

    Toms, David J

    2008-09-26

    The quantum gravitational contribution to the renormalization group behavior of the electric charge in Einstein-Maxwell theory with a cosmological constant is considered. Quantum gravity is shown to lead to a contribution to the running charge not present when the cosmological constant vanishes. This reopens the possibility, suggested by Robinson and Wilczek, of altering the scaling behavior of gauge theories at high energies although our result differs. We show the possibility of an ultraviolet fixed point that is linked directly to the cosmological constant.

  4. Constant symplectic 2-groupoids

    NASA Astrophysics Data System (ADS)

    Mehta, Rajan Amit; Tang, Xiang

    2018-05-01

    We propose a definition of symplectic 2-groupoid which includes integrations of Courant algebroids that have been recently constructed. We study in detail the simple but illustrative case of constant symplectic 2-groupoids. We show that the constant symplectic 2-groupoids are, up to equivalence, in one-to-one correspondence with a simple class of Courant algebroids that we call constant Courant algebroids. Furthermore, we find a correspondence between certain Dirac structures and Lagrangian sub-2-groupoids.

  5. Pedagogical Basis of DAS Formalism in Engineering Education

    ERIC Educational Resources Information Center

    Hiltunen, J.; Heikkinen, E.-P.; Jaako, J.; Ahola, J.

    2011-01-01

    The paper presents a new approach for a bachelor-level curriculum structure in engineering. The approach is called DAS formalism according to its three phases: description, analysis and synthesis. Although developed specifically for process and environmental engineering, DAS formalism has a generic nature and it could also be used in other…

  6. M-DAS: System for multispectral data analysis. [in Saginaw Bay, Michigan

    NASA Technical Reports Server (NTRS)

    Johnson, R. H.

    1975-01-01

    M-DAS is a ground data processing system designed for analysis of multispectral data. M-DAS operates on multispectral data from LANDSAT, S-192, M2S and other sources in CCT form. Interactive training by operator-investigators using a variable cursor on a color display was used to derive optimum processing coefficients and data on cluster separability. An advanced multivariate normal-maximum likelihood processing algorithm was used to produce output in various formats: color-coded film images, geometrically corrected map overlays, moving displays of scene sections, coverage tabulations and categorized CCTs. The analysis procedure for M-DAS involves three phases: (1) screening and training, (2) analysis of training data to compute performance predictions and processing coefficients, and (3) processing of multichannel input data into categorized results. Typical M-DAS applications involve iteration between each of these phases. A series of photographs of the M-DAS display are used to illustrate M-DAS operation.

  7. CODATA Fundamental Physical Constants

    National Institute of Standards and Technology Data Gateway

    SRD 121 NIST CODATA Fundamental Physical Constants (Web, free access)   This site, developed in the Physics Laboratory at NIST, addresses three topics: fundamental physical constants, the International System of Units (SI), which is the modern metric system, and expressing the uncertainty of measurement results.

  8. How to specify and measure sensitivity in Distributed Acoustic Sensing (DAS)?

    NASA Astrophysics Data System (ADS)

    Gabai, Haniel; Eyal, Avishay

    2017-04-01

    In Rayleigh-scattering-based Distributed Acoustic Sensing (DAS) an optical fiber is transformed into an array of thousands of 'virtual microphones'. This approach has gained tremendous popularity in recent years and is one of the most successful examples of a fiber-optic sensing method which made its way from the academia to the market. Despite the great amount of work done in this field, sensitivity, which is ones of the most critical parameters of any sensing technique, was rarely investigated in this context. In particular, little attention was given to its random characteristics. Without careful consideration of the random aspects of DAS, any attempt to specify its sensitivity or to compare between different DAS modalities is of limited value. Recently we introduced a new statistical parameter which defines DAS sensitivity and enables comparison between the performances of different DAS systems. In this paper we generalize the previous parameter and give a broader, simple and intuitive definition to DAS sensitivity. An important attribute of these parameters is that they can be easily extracted from the static backscatter profile of the sensing fiber. In the paper we derive the relation between DAS sensitivity and the static backscatter profile and present an experimental verification of this relation.

  9. Using DAS for reflection seismology - lessons learned from three field studies

    NASA Astrophysics Data System (ADS)

    Freifeld, B. M.; Dou, S.; Ajo Franklin, J. B.; Robertson, M.; Wood, T.; Daley, T. M.; White, D. J.; Worth, K.; Pevzner, R.; Yavuz, S.; dos Santos Maia Correa, J.; McDonald, S.

    2017-12-01

    Distributed acoustic sensing (DAS) has rapidly gained recognition for its potential for seismic imaging. For surface reflection seismology, the wide spatial aperture afforded by DAS is a primary motivation for its application, however the lower SNR of DAS has proven to be a significant impediment to acquiring data that can replace conventional receiver arrays. A further limitation of DAS cables is that the strain-dependent response is insensitive to acoustic energy which arrives orthogonal to the cable axis, reducing its effectiveness at seeing energy reflected from the deep subsurface. To enhance the sensitivity of DAS cables for reflection seismology, we have trialed at three field sites DAS cables with helical construction in which there is a significant component of optical fiber that is coincident with arriving broadside energy. We have installed helically wound DAS cables at the PTRC Aquistore Project in Saskatchewan, Canada and the CO2CRC Otway Project in Nirranda South, Victoria, Australia in shallow trenches. For the ADM Intelligent Monitoring Systems Project in Decatur, Illinois, USA we used a horizontal directional drilling method to install DAS cables at a depth that is greater than can be achieved using trenched installation. At the Otway and ADM sites we operated surface orbital vibrators (SOVs) at fixed locations to enhance sensitivity by stacking large numbers of sweeps. We present survey results from the three sites. Analysis of both vibroseis survey and SOV results show that the helical cable design achieves its primary objective of improving sensitivity to reflected energy, with further gains needed to achieve the sensitivity of conventional geophones.

  10. Study of morphometry to debit drainage basin (DAS) arau Padang city

    NASA Astrophysics Data System (ADS)

    Utama, Lusi; Amrizal, Berd, Isril; Zuherna

    2017-11-01

    High intensity rain that happened in Padang city cause the happening of floods at DAS Arau. Floods that happened in Padang besides caused high rain intensity, require to be by research about morphometry that is cause parameter the happening of floods. Morphometry drainage basin physical network (DAS) quantitatively related to DAS geomorphology that is related to form of DAS, river network, closeness of stream, ramp, usage of farm, high and gradient steepness of river. Form DAS will influence rain concentration to outlet. Make an index to closeness of stream depict closeness of river stream at one particular DAS. Speed of river stream influenced by storey, level steepness of river. Steepness storey, level is comparison of difference height of river downstream and upstream. Ever greater of steepness of river stream, excelsior speed of river stream that way on the contrary. High to lower speed of river stream influence occurrence of floods, more than anything else if when influenced by debit big. Usage of farm in glove its link to process of infiltration where if geology type which is impermeable, be difficult the happening of infiltration, this matter will enlarge value of run off. Research by descriptive qualitative that is about characteristic of DAS. Method the used is method survey with data collecting, in the form of rainfall data of year 2005 until year 2015 and Image of DEM IFSAR with resolution 5 meter, analyzed use Software ARGIS. Result of research got by DAS reside in at condition of floods gristle.

  11. Tachyon constant-roll inflation

    NASA Astrophysics Data System (ADS)

    Mohammadi, A.; Saaidi, Kh.; Golanbari, T.

    2018-04-01

    The constant-roll inflation is studied where the inflaton is taken as a tachyon field. Based on this approach, the second slow-roll parameter is taken as a constant which leads to a differential equation for the Hubble parameter. Finding an exact solution for the Hubble parameter is difficult and leads us to a numerical solution for the Hubble parameter. On the other hand, since in this formalism the slow-roll parameter η is constant and could not be assumed to be necessarily small, the perturbation parameters should be reconsidered again which, in turn, results in new terms appearing in the amplitude of scalar perturbations and the scalar spectral index. Utilizing the numerical solution for the Hubble parameter, we estimate the perturbation parameter at the horizon exit time and compare it with observational data. The results show that, for specific values of the constant parameter η , we could have an almost scale-invariant amplitude of scalar perturbations. Finally, the attractor behavior for the solution of the model is presented, and we determine that the feature could be properly satisfied.

  12. Ground Motion Analysis of Co-Located DAS and Seismometer Sensors

    NASA Astrophysics Data System (ADS)

    Wang, H. F.; Fratta, D.; Lord, N. E.; Lancelle, C.; Thurber, C. H.; Zeng, X.; Parker, L.; Chalari, A.; Miller, D.; Feigl, K. L.; Team, P.

    2016-12-01

    The PoroTomo research team deployed 8700-meters of Distributed Acoustic Sensing (DAS) cable in a shallow trench and 400-meters in a borehole at Brady Hot Springs, Nevada in March 2016 together with an array of 246, three-component geophones. The seismic sensors occupied a natural laboratory 1500 x 500 x 400 meters overlying the Brady geothermal field. The DAS cable was laid out in three parallel zig-zag lines with line segments approximately 100-meters in length and geophones were spaced at approximately 50-m intervals. In several line segments, geophones were co-located within one meter of the DAS cable. Both DAS and the conventional geophones recorded continuously over 15 days. A large Vibroseis truck (T-Rex) provided the seismic source at approximately 250 locations outside and within the array. The Vibroseis protocol called for excitation in one vertical and two orthogonal horizontal directions at each location. For each mode, three, 5-to-80-Hz upsweeps were made over 20 seconds. In addition, a moderate-sized earthquake with a local magnitude of 4.3 was recorded on March 21, 2016. Its epicenter was approximately 150-km away. Several DAS line segments with co-located geophone stations were used to test relationships between the strain rate recorded by DAS and ground velocity recorded by the geophones.

  13. DAS: A Data Management System for Instrument Tests and Operations

    NASA Astrophysics Data System (ADS)

    Frailis, M.; Sartor, S.; Zacchei, A.; Lodi, M.; Cirami, R.; Pasian, F.; Trifoglio, M.; Bulgarelli, A.; Gianotti, F.; Franceschi, E.; Nicastro, L.; Conforti, V.; Zoli, A.; Smart, R.; Morbidelli, R.; Dadina, M.

    2014-05-01

    The Data Access System (DAS) is a and data management software system, providing a reusable solution for the storage of data acquired both from telescopes and auxiliary data sources during the instrument development phases and operations. It is part of the Customizable Instrument WorkStation system (CIWS-FW), a framework for the storage, processing and quick-look at the data acquired from scientific instruments. The DAS provides a data access layer mainly targeted to software applications: quick-look displays, pre-processing pipelines and scientific workflows. It is logically organized in three main components: an intuitive and compact Data Definition Language (DAS DDL) in XML format, aimed for user-defined data types; an Application Programming Interface (DAS API), automatically adding classes and methods supporting the DDL data types, and providing an object-oriented query language; a data management component, which maps the metadata of the DDL data types in a relational Data Base Management System (DBMS), and stores the data in a shared (network) file system. With the DAS DDL, developers define the data model for a particular project, specifying for each data type the metadata attributes, the data format and layout (if applicable), and named references to related or aggregated data types. Together with the DDL user-defined data types, the DAS API acts as the only interface to store, query and retrieve the metadata and data in the DAS system, providing both an abstract interface and a data model specific one in C, C++ and Python. The mapping of metadata in the back-end database is automatic and supports several relational DBMSs, including MySQL, Oracle and PostgreSQL.

  14. Numerical results on the transcendence of constants involving pi, e, and Euler's constant

    NASA Technical Reports Server (NTRS)

    Bailey, David H.

    1988-01-01

    The existence of simple polynomial equations (integer relations) for the constants e/pi, e + pi, log pi, gamma (Euler's constant), e exp gamma, gamma/e, gamma/pi, and log gamma is investigated by means of numerical computations. The recursive form of the Ferguson-Fourcade algorithm (Ferguson and Fourcade, 1979; Ferguson, 1986 and 1987) is implemented on the Cray-2 supercomputer at NASA Ames, applying multiprecision techniques similar to those described by Bailey (1988) except that FFTs are used instead of dual-prime-modulus transforms for multiplication. It is shown that none of the constants has an integer relation of degree eight or less with coefficients of Euclidean norm 10 to the 9th or less.

  15. Constant-Pressure Hydraulic Pump

    NASA Technical Reports Server (NTRS)

    Galloway, C. W.

    1982-01-01

    Constant output pressure in gas-driven hydraulic pump would be assured in new design for gas-to-hydraulic power converter. With a force-multiplying ring attached to gas piston, expanding gas would apply constant force on hydraulic piston even though gas pressure drops. As a result, pressure of hydraulic fluid remains steady, and power output of the pump does not vary.

  16. Construction of Lines of Constant Density and Constant Refractive Index for Ternary Liquid Mixtures.

    ERIC Educational Resources Information Center

    Tasic, Aleksandar Z.; Djordjevic, Bojan D.

    1983-01-01

    Demonstrates construction of density constant and refractive index constant lines in triangular coordinate system on basis of systematic experimental determinations of density and refractive index for both homogeneous (single-phase) ternary liquid mixtures (of known composition) and the corresponding binary compositions. Background information,…

  17. A preliminary psychometric evaluation of Music in Dementia Assessment Scales (MiDAS).

    PubMed

    McDermott, Orii; Orgeta, Vasiliki; Ridder, Hanne Mette; Orrell, Martin

    2014-06-01

    Music in Dementia Assessment Scales (MiDAS), an observational outcome measure for music therapy with people with moderate to severe dementia, was developed from qualitative data of focus groups and interviews. Expert and peer consultations were conducted at each stage of the scale development to maximize its content validity. This study aimed to evaluate the psychometric properties of MiDAS. Care home residents with dementia attended weekly group music therapy for up to ten sessions. Music therapists and care home staff were requested to complete weekly MiDAS ratings. The Quality of Life Scale (QoL-AD) was completed at three time-points. A total of 629 (staff = 306, therapist = 323) MiDAS forms were completed. The statistical analysis revealed that MiDAS has high therapist inter-rater reliability, low staff inter-rater reliability, adequate staff test-retest reliability, adequate concurrent validity, and good construct validity. High factor loadings between the five MiDAS Visual Analogue Scale (VAS) items, levels of Interest, Response, Initiation, Involvement, and Enjoyment, were found. This study indicates that MiDAS has good psychometric properties despite the small sample size. Future research with a larger sample size could provide a more in-depth psychometric evaluation, including further exploration of the underlying factors. MiDAS provides a measure of engagement with musical experience and offers insight into who is likely to benefit on other outcomes such as quality of life or reduction in psychiatric symptoms.

  18. The observational constraint on constant-roll inflation

    NASA Astrophysics Data System (ADS)

    Gao, Qing

    2018-07-01

    We discuss the constant-roll inflation with constant ɛ2 and constant \\bar η . By using the method of Bessel function approximation, the analytical expressions for the scalar and tensor power spectra, the scalar and tensor spectral tilts, and the tensor to scalar ratio are derived up to the first order of ɛ1. The model with constant ɛ2 is ruled out by the observations at the 3σ confidence level, and the model with constant \\bar η is consistent with the observations at the 1σ confidence level. The potential for the model with constant \\bar η is also obtained from the Hamilton-Jacobi equation. Although the observations constrain the constant-roll inflation to be the slow-roll inflation, the n s- r results from the constant-roll inflation are not the same as those from the slow-roll inflation even when \\bar η 0.01.

  19. Elastic constants of calcite

    USGS Publications Warehouse

    Peselnick, L.; Robie, R.A.

    1962-01-01

    The recent measurements of the elastic constants of calcite by Reddy and Subrahmanyam (1960) disagree with the values obtained independently by Voigt (1910) and Bhimasenachar (1945). The present authors, using an ultrasonic pulse technique at 3 Mc and 25??C, determined the elastic constants of calcite using the exact equations governing the wave velocities in the single crystal. The results are C11=13.7, C33=8.11, C44=3.50, C12=4.82, C13=5.68, and C14=-2.00, in units of 1011 dyncm2. Independent checks of several of the elastic constants were made employing other directions and polarizations of the wave velocities. With the exception of C13, these values substantially agree with the data of Voigt and Bhimasenachar. ?? 1962 The American Institute of Physics.

  20. Connecting Fundamental Constants

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

    Di Mario, D.

    2008-05-29

    A model for a black hole electron is built from three basic constants only: h, c and G. The result is a description of the electron with its mass and charge. The nature of this black hole seems to fit the properties of the Planck particle and new relationships among basic constants are possible. The time dilation factor in a black hole associated with a variable gravitational field would appear to us as a charge; on the other hand the Planck time is acting as a time gap drastically limiting what we are able to measure and its dimension willmore » appear in some quantities. This is why the Planck time is numerically very close to the gravitational/electric force ratio in an electron: its difference, disregarding a {pi}{radical}(2) factor, is only 0.2%. This is not a coincidence, it is always the same particle and the small difference is between a rotating and a non-rotating particle. The determination of its rotational speed yields accurate numbers for many quantities, including the fine structure constant and the electron magnetic moment.« less

  1. How fundamental are fundamental constants?

    NASA Astrophysics Data System (ADS)

    Duff, M. J.

    2015-01-01

    I argue that the laws of physics should be independent of one's choice of units or measuring apparatus. This is the case if they are framed in terms of dimensionless numbers such as the fine structure constant, ?. For example, the standard model of particle physics has 19 such dimensionless parameters whose values all observers can agree on, irrespective of what clock, rulers or scales? they use to measure them. Dimensional constants, on the other hand, such as ?, c, G, e and k ?, are merely human constructs whose number and values differ from one choice of units to the next. In this sense, only dimensionless constants are 'fundamental'. Similarly, the possible time variation of dimensionless fundamental 'constants' of nature is operationally well defined and a legitimate subject of physical enquiry. By contrast, the time variation of dimensional constants such as ? or ? on which a good many (in my opinion, confusing) papers have been written, is a unit-dependent phenomenon on which different observers might disagree depending on their apparatus. All these confusions disappear if one asks only unit-independent questions. We provide a selection of opposing opinions in the literature and respond accordingly.

  2. Effective optical constants of anisotropic materials

    NASA Technical Reports Server (NTRS)

    Aronson, J. R.; Emslie, A. G.

    1980-01-01

    The applicability of a technique for determining the optical constants of soil or aerosol components on the basis of measurements of the reflectance or transmittance of inhomogeneous samples of component material is investigated. Optical constants for a sample of very pure quartzite were obtained by a specular reflection technique and line parameters were calculated by classical dispersion theory. Predictions of the reflectance of powdered quartz were then derived from optical constants measured for the anisotropic quartz and for pure quartz crystals, and compared with experimental measurements. The calculated spectra are found to resemble each other moderately well in shape, however the reflectance level calculated from the psuedo-optical constants (quartzite) is consistently below that calculated from quartz values. The spectrum calculated from the quartz optical constants is also shown to represent the experimental nonrestrahlen features more accurately. It is thus concluded that although optical constants derived from inhomogeneous materials may represent the spectral features of a powdered sample qualitatively a quantitative fit to observed data is not likely.

  3. Constant Communities in Complex Networks

    NASA Astrophysics Data System (ADS)

    Chakraborty, Tanmoy; Srinivasan, Sriram; Ganguly, Niloy; Bhowmick, Sanjukta; Mukherjee, Animesh

    2013-05-01

    Identifying community structure is a fundamental problem in network analysis. Most community detection algorithms are based on optimizing a combinatorial parameter, for example modularity. This optimization is generally NP-hard, thus merely changing the vertex order can alter their assignments to the community. However, there has been less study on how vertex ordering influences the results of the community detection algorithms. Here we identify and study the properties of invariant groups of vertices (constant communities) whose assignment to communities are, quite remarkably, not affected by vertex ordering. The percentage of constant communities can vary across different applications and based on empirical results we propose metrics to evaluate these communities. Using constant communities as a pre-processing step, one can significantly reduce the variation of the results. Finally, we present a case study on phoneme network and illustrate that constant communities, quite strikingly, form the core functional units of the larger communities.

  4. Universe of constant

    NASA Astrophysics Data System (ADS)

    Yongquan, Han

    2016-10-01

    The ideal gas state equation is not applicable to ordinary gas, it should be applied to the Electromagnetic ``gas'' that is applied to the radiation, the radiation should be the ultimate state of matter changes or initial state, the universe is filled with radiation. That is, the ideal gas equation of state is suitable for the Singular point and the universe. Maybe someone consider that, there is no vessel can accommodate radiation, it is because the Ordinary container is too small to accommodate, if the radius of your container is the distance that Light through an hour, would you still think it can't accommodates radiation? Modern scientific determinate that the radius of the universe now is about 1027 m, assuming that the universe is a sphere whose volume is approximately: V = 4.19 × 1081 cubic meters, the temperature radiation of the universe (cosmic microwave background radiation temperature of the universe, should be the closest the average temperature of the universe) T = 3.15k, radiation pressure P = 5 × 10-6 N / m 2, according to the law of ideal gas state equation, PV / T = constant = 6 × 1075, the value of this constant is the universe, The singular point should also equal to the constant Author: hanyongquan

  5. Crosslinking effect of dialdehyde starch (DAS) on decellularized porcine aortas for tissue engineering.

    PubMed

    Wang, Xu; Gu, Zhipeng; Qin, Huanhuan; Li, Li; Yang, Xu; Yu, Xixun

    2015-08-01

    Biological tissue-derived biomaterials must be chemically modified to avoid immediate degradation and immune response before being implanted in human body to replace malfunctioning organs. DAS with active aldehyde groups was employed to replace glutaraldehyde (GA), a most common synthetic crosslinking reagent in clinical practice, to fix bioprostheses for lower cytotoxicity. The aim of this research was to evaluate fixation effect of DAS. The tensile strength, crosslinking stability, cytotoxicity especially the anti-calcification capability of DAS-fixed tissues were investigated. The tensile strength and resistance to enzymatic degradation of samples were increased after DAS fixation, the values maintained stably in D-Hanks solution for several days. Meanwhile, ultrastructure of samples preserved well and the anti-calcification capability of samples were improved, the amount of positive staining points in the whole visual field of 15% DAS-fixed samples was only 0.576 times to GA-fixed ones. Moreover, both unreacted DAS and its hydrolytic products were nontoxic in cytotoxicity study. The results demonstrated DAS might be an effective crosslinking reagent to fix biological tissue-derived biomaterials in tissue engineering. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. A Safety Evaluation of DAS181, a Sialidase Fusion Protein, in Rodents

    PubMed Central

    Larson, Jeffrey L.; Kang, Seong-Kwi; Choi, Bo In; Hedlund, Maria; Aschenbrenner, Laura M.; Cecil, Beth; Machado, GloriaMay; Nieder, Matthew; Fang, Fang

    2011-01-01

    DAS181 is a novel inhaled drug candidate blocking influenza virus (IFV) and parainfluenza virus (PIV) infections through removal of sialic acid receptors from epithelial surface of the respiratory tract. To support clinical development, a 28-day Good Laboratory Practices inhalation toxicology study was conducted in Sprague-Dawley rats. In this study, achieved average daily doses based on exposure concentrations were 0.47, 0.90, 1.55, and 3.00 mg/kg/day of DAS181 in a dry powder formulation. DAS181 was well tolerated at all dose levels, and there were no significant toxicological findings. DAS181 administration did not affect animal body weight, food consumption, clinical signs, ophthalmology, respiratory parameters, or organ weight. Gross pathology evaluations were unremarkable. Histological examination of the lungs was devoid of pulmonary tissue damage, and findings were limited to mild and transient changes indicative of exposure and clearance of a foreign protein. DAS181 did not show any cytotoxic effects on human and animal primary cells, including hepatocytes, skeletal muscle cells, osteoblasts, or respiratory epithelial cells. DAS181 did not cause direct or indirect hemolysis. A laboratory abnormality observed in the 28-day toxicology study was mild and transient anemia in male rats at the 3.00 mg/kg dose, which is an expected outcome of enhanced clearance of desialylated red blood cells resulting from systemic exposure with DAS181. Another laboratory observation was a transient dose-dependent elevation in alkaline phosphatase (ALP), which can be attributed to reduced ALP clearance resulting from increased protein desialylation due to DAS181 systemic exposure. These laboratory parameters returned to normal at the end of the recovery period. PMID:21572096

  7. Larson-Miller Constant of Heat-Resistant Steel

    NASA Astrophysics Data System (ADS)

    Tamura, Manabu; Abe, Fujio; Shiba, Kiyoyuki; Sakasegawa, Hideo; Tanigawa, Hiroyasu

    2013-06-01

    Long-term rupture data for 79 types of heat-resistant steels including carbon steel, low-alloy steel, high-alloy steel, austenitic stainless steel, and superalloy were analyzed, and a constant for the Larson-Miller (LM) parameter was obtained in the current study for each material. The calculated LM constant, C, is approximately 20 for heat-resistant steels and alloys except for high-alloy martensitic steels with high creep resistance, for which C ≈ 30 . The apparent activation energy was also calculated, and the LM constant was found to be proportional to the apparent activation energy with a high correlation coefficient, which suggests that the LM constant is a material constant possessing intrinsic physical meaning. The contribution of the entropy change to the LM constant is not small, especially for several martensitic steels with large values of C. Deformation of such martensitic steels should accompany a large entropy change of 10 times the gas constant at least, besides the entropy change due to self-diffusion.

  8. Amerikas Einschätzung der deutschen Atomforschung: Das deutsche Uranprojekt

    NASA Astrophysics Data System (ADS)

    Walker, Mark

    2002-07-01

    Die amerikanischen Wissenschaftler und ihre emigrierten Kollegen, die am Bau der Atombombe beteiligt waren, verfügten über sehr widersprüchliche und großteils falsche Informationen über den Fortschritt des deutschen Uranprogramms. Noch nach Kriegsende lässt sich dies an Aussagen des Leiters der amerikanischen Alsos-Mission, Samuel Goudsmit, festmachen. Tatsächlich war das deutsche Programm hinsichtlich seiner wissenschaftlichen Grundlagen und des Managements nicht so unterlegen, wie vielfach behauptet wurde. Aber die deutschen Behörden waren nicht in der Lage, Geld und Ressourcen in gleichem Maße in das Uranprojekt zu investieren, wie etwa in das Peenemünder Raketenprojekt.

  9. Constant potential pulse polarography

    USGS Publications Warehouse

    Christie, J.H.; Jackson, L.L.; Osteryoung, R.A.

    1976-01-01

    The new technique of constant potential pulse polarography, In which all pulses are to be the same potential, is presented theoretically and evaluated experimentally. The response obtained is in the form of a faradaic current wave superimposed on a constant capacitative component. Results obtained with a computer-controlled system exhibit a capillary response current similar to that observed In normal pulse polarography. Calibration curves for Pb obtained using a modified commercial pulse polarographic instrument are in good accord with theoretical predictions.

  10. Constant-roll tachyon inflation and observational constraints

    NASA Astrophysics Data System (ADS)

    Gao, Qing; Gong, Yungui; Fei, Qin

    2018-05-01

    For the constant-roll tachyon inflation, we derive the analytical expressions for the scalar and tensor power spectra, the scalar and tensor spectral tilts and the tensor to scalar ratio to the first order of epsilon1 by using the method of Bessel function approximation. The derived ns-r results are compared with the observations, we find that only the constant-roll inflation with ηH being a constant is consistent with the observations and observations constrain the constant-roll inflation to be slow-roll inflation. The tachyon potential is also reconstructed for the constant-roll inflation which is consistent with the observations.

  11. Elastic constants and pressure derivative of elastic constants of Si1-xGex solid solution

    NASA Astrophysics Data System (ADS)

    Jivani, A. R.; Baria, J. K.; Vyas, P. S.; Jani, A. R.

    2013-02-01

    Elastic properties of Si1-xGex solid solution with arbitrary (atomic) concentration (x) are studied using the pseudo-alloy atom model based on the pseudopotential theory and on the higher-order perturbation scheme with the application of our own proposed model potential. We have used local-field correction function proposed by Sarkar et al to study Si-Ge system. The Elastic constants and pressure derivatives of elastic constants of the solid solution is investigated with different concentration x of Ge. It is found in the present study that the calculated numerical values of the aforesaid physical properties of Si-Ge system are function of x. The elastic constants (C11, C12 and C44) decrease linearly with increase in concentration x and pressure derivative of elastic constants (C11, C12 and C44) increase with the concentration x of Ge. This study provides better set of theoretical results for such solid solution for further comparison either with theoretical or experimental results.

  12. Present status of astronomical constants

    NASA Astrophysics Data System (ADS)

    Fukushima, T.

    Given was the additional information to the previous report on the recent progress in the determinations of astronomical constants (Fukushima 2000). First noted was the revision of LG as 6.969290134×10-10 based on the proposal to shift its status from a primary to a defining constant (Petit 2000). Next focused was the significant update of the correction to the current precession constant, Δp, based on the recent LLR-based determination (Chapront et al. 2000) as -0.3164+/-0.0030"/cy. By combining this and the equal weighted average of VLBI determinations (Mathews et al. 2000; Petrov 2000; Shirai and Fukushima 2000; Vondrak and Ron 2000) as -0.2968+/-0.0043"/cy, we derived the best estimate of precession constant as p = 5028.790+/-0.005"/cy. Also redetermined were some other quantities related to the precession formula; namely the offsets of Celestial Ephemeris Pole of the International Celestial Reference System as &Deltaψ0sinɛ0 = (-17.0+/-0.3) mas and Δɛ0 = (-5.1+/-0.3) mas. As a result, the obliquity of the ecliptic at the epoch J2000.0 was estimated as ɛ0 = 23°26'21."4059+/-0."0003. As a summary, presented was the (revised) IAU 2000 File of Current Best Estimates of astronomical constants, which is to replace the former 1994 version (Standish 1995).

  13. Graviton fluctuations erase the cosmological constant

    NASA Astrophysics Data System (ADS)

    Wetterich, C.

    2017-10-01

    Graviton fluctuations induce strong non-perturbative infrared renormalization effects for the cosmological constant. The functional renormalization flow drives a positive cosmological constant towards zero, solving the cosmological constant problem without the need to tune parameters. We propose a simple computation of the graviton contribution to the flow of the effective potential for scalar fields. Within variable gravity, with effective Planck mass proportional to the scalar field, we find that the potential increases asymptotically at most quadratically with the scalar field. The solutions of the derived cosmological equations lead to an asymptotically vanishing cosmological "constant" in the infinite future, providing for dynamical dark energy in the present cosmological epoch. Beyond a solution of the cosmological constant problem, our simplified computation also entails a sizeable positive graviton-induced anomalous dimension for the quartic Higgs coupling in the ultraviolet regime, substantiating the successful prediction of the Higgs boson mass within the asymptotic safety scenario for quantum gravity.

  14. DAS Microseismic and Strain Monitoring During Hydraulic Fracturing

    NASA Astrophysics Data System (ADS)

    Kahn, D.; Karrenbach, M. H.; Cole, S.; Boone, K.; Ridge, A.; Rich, J.; Langton, D.; Silver, K.

    2017-12-01

    Hydraulic fracturing operations in unconventional subsurface reservoirs are typically monitored using geophones located either at the surface or in adjacent wellbores. A novel approach to record hydraulic stimulations utilizes fiber-optic Distributed Acoustic Sensing (DAS). A fiber-optic cable was installed in a treatment well in a subsurface reservoir (Meramec formation). DAS data were recorded during fluid injection of same fibered well and also during injection into a nearby treatment well at a distance of 350m. For both scenarios the DAS sensing array consisted of approximately 1000 channels at a fine spatial and temporal sampling and with a large sensing aperture. Thus, the full strain wave field is measured along the borehole over its entire length. A variety of physical effects, such as temperature, low-frequency strain and microseismicity were measured and correlated with the treatment program during hydraulic fracturing of the wells. These physical effects occur at various frequency scales and produce complementary measurements. Microseismic events in the magnitude range of -0.5 and -2.0 at a maximum distance of 500m were observed and analyzed for recordings from the fiber-equipped treatment well and also neighboring treatment well. The analysis of this DAS data set demonstrates that current fiber-optic sensing technology can provide enough sensitivity to detect a significant number of microseismic events and that these events can be integrated with temperature and strain measurements for an improved subsurface reservoir description.

  15. Effects of Constant Flow vs. Constant Pressure Perfusion on Fluid Filtration in Severe Hypothermic Isolated Blood-Perfused Rat Lungs.

    PubMed

    Halsøy, Kathrine; Kondratiev, Timofey; Tveita, Torkjel; Bjertnaes, Lars J

    2016-01-01

    Victims of severe accidental hypothermia are prone to fluid extravasation but rarely develop lung edema. We hypothesize that combined hypothermia-induced increase in pulmonary vascular resistance (PVR) and a concomitant fall in cardiac output protect the lungs against edema development. Our aim was to explore in hypothermic-isolated blood-perfused rat lungs whether perfusion at constant pressure influences fluid filtration differently from perfusion at constant flow. Isolated blood-perfused rat lungs were hanging freely in a weight transducer for measuring weight changes (ΔW). Fluid filtration coefficient (Kfc), was determined by transiently elevating left atrial pressure (Pla) by 5.8 mmHg two times each during normothermia (37°C) and during hypothermia (15°C). The lung preparations were randomized to two groups. One group was perfused with constant flow (Constant flow group) and the other group with constant pulmonary artery pressure (Constant PPA group). Microvascular pressure (Pmv) was determined before and during elevation of Pla (ΔPmv) by means of the double occlusion technique. Kfc was calculated with the formula Kfc = ΔW/ΔPmv/min. All Kfc values were normalized to predicted lung weight (P LW ), which was based on body weight (BW) according to the formula: P LW  = 0.0053 BW - 0.48 and presented as Kfc PLW in mg/min/mmHg/g. At cessation, bronchoalveolar lavage (BAL) fluid/perfusate protein concentration (B/P) ratio was determined photometrically. Data were analyzed with parametric or non-parametric tests as appropriate. p  < 0.05 considered as significant. Perfusate flow remained constant in the Constant flow group, but was more than halved during hypothermia in the Constant PPA group concomitant with a more fold increase in PVR. In the Constant flow group, Kfc PLW and B/P ratio increased significantly by more than 10-fold during hypothermia concerted by visible signs of edema in the trachea. Hemoglobin and hematocrit increased within

  16. CODATA recommended values of the fundamental constants

    NASA Astrophysics Data System (ADS)

    Mohr, Peter J.; Taylor, Barry N.

    2000-11-01

    A review is given of the latest Committee on Data for Science and Technology (CODATA) adjustment of the values of the fundamental constants. The new set of constants, referred to as the 1998 values, replaces the values recommended for international use by CODATA in 1986. The values of the constants, and particularly the Rydberg constant, are of relevance to the calculation of precise atomic spectra. The standard uncertainty (estimated standard deviation) of the new recommended value of the Rydberg constant, which is based on precision frequency metrology and a detailed analysis of the theory, is approximately 1/160 times the uncertainty of the 1986 value. The new set of recommended values as well as a searchable bibliographic database that gives citations to the relevant literature is available on the World Wide Web at physics.nist.gov/constants and physics.nist.gov/constantsbib, respectively. .

  17. The Henry's constant of monochloramine.

    PubMed

    Garcia, Miguel A; Anderson, Michael A

    2018-02-01

    Monochloramine is a secondary disinfectant used in drinking water and is also formed in chlorinated wastewater. While known to hydrolyze over time and react with dissolved organic matter, its partitioning between the aqueous and gas phase has not been extensively studied. Preliminary experiments demonstrated that monochloramine concentrations in solutions open to the atmosphere or actively aerated decreased more rapidly than in sealed solutions, indicating significant losses to the atmosphere. For example, a monochloramine solution open to the atmosphere yielded a loss rate constant of 0.08 d -1 , a value twice that for sealed samples without headspace (0.04 d -1 ) where loss occurs exclusively as a result of hydrolysis. A solution aerated at 10 mL s -1 had a loss rate constant nearly 10× greater than that for hydrolysis alone (0.35 d -1 ). To better understand partitioning of monochloramine to the gas phase and potential for volatilization, the dimensionless Henry's law constants of monochloramine (K H ) were determined using an equilibrium headspace technique at five different temperatures (11, 16, 21, 27, and 32 °C). The resulting values ranged from 8 × 10 -3 to 4 × 10 -2 , indicating a semi-volatile compound, and were found to be consistent with quantitative structure activity relationship predictions. At 20 °C, monochloramine exhibits a dimensionless Henry's constant of about 1.7 × 10 -2 which is 35 times greater than ammonia but comparable to the Henry's constant of inorganic semi-volatile compounds such sulfur dioxide. The Henry's constant values for monochloramine suggests that volatilization could be a relevant loss process in open systems such as rivers receiving chlorinated wastewater effluent, swimming pools and cooling towers. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Constant voltage electro-slag remelting control

    DOEpatents

    Schlienger, M.E.

    1996-10-22

    A system for controlling electrode gap in an electro-slag remelt furnace has a constant regulated voltage and an electrode which is fed into the slag pool at a constant rate. The impedance of the circuit through the slag pool is directly proportional to the gap distance. Because of the constant voltage, the system current changes are inversely proportional to changes in gap. This negative feedback causes the gap to remain stable. 1 fig.

  19. Constant voltage electro-slag remelting control

    DOEpatents

    Schlienger, Max E.

    1996-01-01

    A system for controlling electrode gap in an electro-slag remelt furnace has a constant regulated voltage and an eletrode which is fed into the slag pool at a constant rate. The impedance of the circuit through the slag pool is directly proportional to the gap distance. Because of the constant voltage, the system current changes are inversely proportional to changes in gap. This negative feedback causes the gap to remain stable.

  20. Distributed Acoustic Sensing (DAS) Data for Periodic Hydraulic Tests

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

    Coleman, Thomas; Becker, Matthew

    California State University Long Beach evaluated hydraulic connectivity among geothermal wells using Periodic Hydraulic Testing (PHT) and Distributed Acoustic Sensing (DAS). The principal was to create a pressure signal in one well and observe the responding pressure signals in one or more observation wells to assess the permeability and storage of the fracture network that connects the two wells. DAS measured strain at mHz frequency in monitoring wells in response to PHT.

  1. New perspectives on constant-roll inflation

    NASA Astrophysics Data System (ADS)

    Cicciarella, Francesco; Mabillard, Joel; Pieroni, Mauro

    2018-01-01

    We study constant-roll inflation using the β-function formalism. We show that the constant rate of the inflaton roll is translated into a first order differential equation for the β-function which can be solved easily. The solutions to this equation correspond to the usual constant-roll models. We then construct, by perturbing these exact solutions, more general classes of models that satisfy the constant-roll equation asymptotically. In the case of an asymptotic power law solution, these corrections naturally provide an end to the inflationary phase. Interestingly, while from a theoretical point of view (in particular in terms of the holographic interpretation) these models are intrinsically different from standard slow-roll inflation, they may have phenomenological predictions in good agreement with present cosmological data.

  2. Phenotypic and genotypic characterization of influenza virus mutants selected with the sialidase fusion protein DAS181

    PubMed Central

    Triana-Baltzer, Gallen B.; Sanders, Rebecca L.; Hedlund, Maria; Jensen, Kellie A.; Aschenbrenner, Laura M.; Larson, Jeffrey L.; Fang, Fang

    2011-01-01

    Background Influenza viruses (IFVs) frequently achieve resistance to antiviral drugs, necessitating the development of compounds with novel mechanisms of action. DAS181 (Fludase®), a sialidase fusion protein, may have a reduced potential for generating drug resistance due to its novel host-targeting mechanism of action. Methods IFV strains B/Maryland/1/59 and A/Victoria/3/75 (H3N2) were subjected to >30 passages under increasing selective pressure with DAS181. The DAS181-selected IFV isolates were characterized in vitro and in mice. Results Despite extensive passaging, DAS181-selected viruses exhibited a very low level of resistance to DAS181, which ranged between 3- and 18-fold increase in EC50. DAS181-selected viruses displayed an attenuated phenotype in vitro, as exhibited by slower growth, smaller plaque size and increased particle to pfu ratios relative to wild-type virus. Further, the DAS181 resistance phenotype was unstable and was substantially reversed over time upon DAS181 withdrawal. In mice, the DAS181-selected viruses exhibited no greater virulence than their wild-type counterparts. Genotypic and phenotypic analysis of DAS181-selected viruses revealed mutations in the haemagglutinin (HA) and neuraminidase (NA) molecules and also changes in HA and NA function. Conclusions Results indicate that resistance to DAS181 is minimal and unstable. The DAS181-selected IFV isolates exhibit reduced fitness in vitro, likely due to altered HA and NA functions. PMID:21097900

  3. Capacitive Cells for Dielectric Constant Measurement

    ERIC Educational Resources Information Center

    Aguilar, Horacio Munguía; Maldonado, Rigoberto Franco

    2015-01-01

    A simple capacitive cell for dielectric constant measurement in liquids is presented. As an illustrative application, the cell is used for measuring the degradation of overheated edible oil through the evaluation of their dielectric constant.

  4. The Hubble Constant.

    PubMed

    Jackson, Neal

    2015-01-01

    I review the current state of determinations of the Hubble constant, which gives the length scale of the Universe by relating the expansion velocity of objects to their distance. There are two broad categories of measurements. The first uses individual astrophysical objects which have some property that allows their intrinsic luminosity or size to be determined, or allows the determination of their distance by geometric means. The second category comprises the use of all-sky cosmic microwave background, or correlations between large samples of galaxies, to determine information about the geometry of the Universe and hence the Hubble constant, typically in a combination with other cosmological parameters. Many, but not all, object-based measurements give H 0 values of around 72-74 km s -1 Mpc -1 , with typical errors of 2-3 km s -1 Mpc -1 . This is in mild discrepancy with CMB-based measurements, in particular those from the Planck satellite, which give values of 67-68 km s -1 Mpc -1 and typical errors of 1-2 km s -1 Mpc -1 . The size of the remaining systematics indicate that accuracy rather than precision is the remaining problem in a good determination of the Hubble constant. Whether a discrepancy exists, and whether new physics is needed to resolve it, depends on details of the systematics of the object-based methods, and also on the assumptions about other cosmological parameters and which datasets are combined in the case of the all-sky methods.

  5. Relativistic problems on astronomical constants.

    NASA Astrophysics Data System (ADS)

    Tao, Jinhe; Huang, Tianyi

    1999-06-01

    The fact that modern astronomical observational technique has made rapid progress and the 1PN approximation of general relativity has been extensively applied in celestial mechanics and astrometry, makes it is necessary to investigate and examine the system of astronomical constants carefully and rigorously in the relativistic framework. The mass of a celestial body in the solar system should be defined as its BD mass that changes relatively in an amount less than 10-19 and could be considered as a constant. The equations satisfied by the gravitational potentials are not Poisson equations anymore but depend on the choice of the coordinate gauge. Therefore the gravitational potentials cannot be expanded in the traditional harmonics. It is neccessary to choose the coordinate gauge and take BD multipole moments as astronomical constants. The obliquity of the ecliptic has been determined in high precision and it would be neccessary to give a conventional definition of the 1PN ecliptic. A relativistic definition of the geoid is important and left to be discussed. The astronomical constants that relate the units of time and length have been clearly defined but need to be clarified to avoid their misuse.

  6. MATHEMATICAL CONSTANTS.

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

    Robinson, H.P.; Potter, Elinor

    1971-03-01

    This collection of mathematical data consists of two tables of decimal constants arranged according to size rather than function, a third table of integers from 1 to 1000, giving some of their properties, and a fourth table listing some infinite series arranged according to increasing size of the coefficients of the terms. The decimal values of Tables I and II are given to 20 D.

  7. The 1% concordance Hubble constant

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

    Bennett, C. L.; Larson, D.; Weiland, J. L.

    2014-10-20

    The determination of the Hubble constant has been a central goal in observational astrophysics for nearly a hundred years. Extraordinary progress has occurred in recent years on two fronts: the cosmic distance ladder measurements at low redshift and cosmic microwave background (CMB) measurements at high redshift. The CMB is used to predict the current expansion rate through a best-fit cosmological model. Complementary progress has been made with baryon acoustic oscillation (BAO) measurements at relatively low redshifts. While BAO data do not independently determine a Hubble constant, they are important for constraints on possible solutions and checks on cosmic consistency. Amore » precise determination of the Hubble constant is of great value, but it is more important to compare the high and low redshift measurements to test our cosmological model. Significant tension would suggest either uncertainties not accounted for in the experimental estimates or the discovery of new physics beyond the standard model of cosmology. In this paper we examine in detail the tension between the CMB, BAO, and cosmic distance ladder data sets. We find that these measurements are consistent within reasonable statistical expectations and we combine them to determine a best-fit Hubble constant of 69.6 ± 0.7 km s{sup –1} Mpc{sup –1}. This value is based upon WMAP9+SPT+ACT+6dFGS+BOSS/DR11+H {sub 0}/Riess; we explore alternate data combinations in the text. The combined data constrain the Hubble constant to 1%, with no compelling evidence for new physics.« less

  8. Carter constant and angular momentum

    NASA Astrophysics Data System (ADS)

    Mukherjee, Sajal; Nayak, K. Rajesh

    We investigate the Carter-like constant in the case of a particle moving in a nonrelativistic dipolar potential. This special case is a missing link between the Carter constant in stationary and axially symmetric spacetimes (SASS) such as Kerr solution and its possible Newtonian counterpart. We use this system to carry over the definition of angular momentum from the Newtonian mechanics to the relativistic SASS.

  9. High-Temperature Slow Crack Growth of Silicon Carbide Determined by Constant-Stress-Rate and Constant-Stress Testing

    NASA Technical Reports Server (NTRS)

    Choi, Sung H.; Salem, J. A.; Nemeth, N. N.

    1998-01-01

    High-temperature slow-crack-growth behaviour of hot-pressed silicon carbide was determined using both constant-stress-rate ("dynamic fatigue") and constant-stress ("static fatigue") testing in flexure at 1300 C in air. Slow crack growth was found to be a governing mechanism associated with failure of the material. Four estimation methods such as the individual data, the Weibull median, the arithmetic mean and the median deviation methods were used to determine the slow crack growth parameters. The four estimation methods were in good agreement for the constant-stress-rate testing with a small variation in the slow-crack-growth parameter, n, ranging from 28 to 36. By contrast, the variation in n between the four estimation methods was significant in the constant-stress testing with a somewhat wide range of n= 16 to 32.

  10. Local probe studies on lattice distortions and electronic correlations in manganites

    NASA Astrophysics Data System (ADS)

    Lopes, Armandina Maria Lima

    Nesta tese apresenta-se um estudo experimental das distorcoes locais e correlacoes electronicas em oxidos magneticos com magnetoresistencia colossal. A tecnica de sonda local - Correlacao Angular Perturbada - e utilizada em amostras caracterizadas quanto as suas propriedades macroscopicas nomeadamente propriedades estruturais, magneticas e electricas, tendo em vista a obtencao de informacao microscopica relevante via gradiente de campo electrico e campo magnetico hiperfino, focando em particular os seguintes aspectos: -Distorcoes de rede e agregados de polaroes no sistema LaMnO3+Delta. E apresentado um estudo dos gradientes de campo electrica e campo magnetico hiperfino em amostras representativas do sistema LaMnO3+Delta, correlacionando estas propriedades locais com a caracterizacao das propriedades macroscopicas, efectuada nas mesmas amostras. Desta forma, foi possivel estudar a natureza microscopica das distorcoes polaronicas. Foi dada especial atencao ao composto com composicao LaMnO3.12 uma vez que este e um sistema padrao de uma manganite ferromagnetica-isoladora que apresenta uma transicao estrutural romboedrica (R)-ortorrombica (O) perto da temperatura ambiente. O estudo revelou que agregados de distorcoes locais sobrevivem ate 776 K, na fase de estrutura media mais simetrica (romboedrica), onde, por simetria, os octaedros MnO6 deveriam ser regulares. Estas distorcoes sao semelhantes as observadas no sistema LaMnO3 onde os octaedros MnO6 apresentam uma distorcao Jahn-Teller colectiva. Com a diminuicao da temperatura observa-se um aumento continuo destes agregados. Abaixo de uma temperatura critica estas distorcoes relaxam acomodando-se numa estrutura com reduzidas distorcoes Jahn-teller. Verificou-se tambem que a transicao estrutural (macroscopica) pode ser entendida como uma transicao de percolacao dos ambientes microscopicos. -Coexistencia das ordens electrica e magnetica no sistema Pr1-xCaxMnO3. E apresentado o primeiro estudo de gradiente de campo

  11. REACTOR PHYSICS CONSTANTS

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

    None

    1963-07-01

    This second edition is based on data available on March 15, 1961. Sections on constants necessary for the interpretation of experimental data and on digital computer programs for reactor design and reactor physics have been added. 1344 references. (D.C.W.)

  12. Adjoint-based constant-mass partial derivatives

    DOE PAGES

    Favorite, Jeffrey A.

    2017-09-01

    In transport theory, adjoint-based partial derivatives with respect to mass density are constant-volume derivatives. Likewise, adjoint-based partial derivatives with respect to surface locations (i.e., internal interface locations and the outer system boundary) are constant-density derivatives. This study derives the constant-mass partial derivative of a response with respect to an internal interface location or the outer system boundary and the constant-mass partial derivative of a response with respect to the mass density of a region. Numerical results are given for a multiregion two-dimensional (r-z) cylinder for three very different responses: the uncollided gamma-ray flux at an external detector point, k effmore » of the system, and the total neutron leakage. Finally, results from the derived formulas compare extremely well with direct perturbation calculations.« less

  13. Systematics of constant roll inflation

    NASA Astrophysics Data System (ADS)

    Anguelova, Lilia; Suranyi, Peter; Wijewardhana, L. C. R.

    2018-02-01

    We study constant roll inflation systematically. This is a regime, in which the slow roll approximation can be violated. It has long been thought that this approximation is necessary for agreement with observations. However, recently it was understood that there can be inflationary models with a constant, and not necessarily small, rate of roll that are both stable and compatible with the observational constraint ns ≈ 1. We investigate systematically the condition for such a constant-roll regime. In the process, we find a whole new class of inflationary models, in addition to the known solutions. We show that the new models are stable under scalar perturbations. Finally, we find a part of their parameter space, in which they produce a nearly scale-invariant scalar power spectrum, as needed for observational viability.

  14. Inflation with a constant rate of roll

    NASA Astrophysics Data System (ADS)

    Motohashi, Hayato; Starobinsky, Alexei A.; Yokoyama, Jun'ichi

    2015-09-01

    We consider an inflationary scenario where the rate of inflaton roll defined by ̈phi/H dot phi remains constant. The rate of roll is small for slow-roll inflation, while a generic rate of roll leads to the interesting case of 'constant-roll' inflation. We find a general exact solution for the inflaton potential required for such inflaton behaviour. In this model, due to non-slow evolution of background, the would-be decaying mode of linear scalar (curvature) perturbations may not be neglected. It can even grow for some values of the model parameter, while the other mode always remains constant. However, this always occurs for unstable solutions which are not attractors for the given potential. The most interesting particular cases of constant-roll inflation remaining viable with the most recent observational data are quadratic hilltop inflation (with cutoff) and natural inflation (with an additional negative cosmological constant). In these cases even-order slow-roll parameters approach non-negligible constants while the odd ones are asymptotically vanishing in the quasi-de Sitter regime.

  15. Inflation with a constant rate of roll

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

    Motohashi, Hayato; Starobinsky, Alexei A.; Yokoyama, Jun'ichi, E-mail: motohashi@kicp.uchicago.edu, E-mail: alstar@landau.ac.ru, E-mail: yokoyama@resceu.s.u-tokyo.ac.jp

    2015-09-01

    We consider an inflationary scenario where the rate of inflaton roll defined by {sup ··}φ/H φ-dot remains constant. The rate of roll is small for slow-roll inflation, while a generic rate of roll leads to the interesting case of 'constant-roll' inflation. We find a general exact solution for the inflaton potential required for such inflaton behaviour. In this model, due to non-slow evolution of background, the would-be decaying mode of linear scalar (curvature) perturbations may not be neglected. It can even grow for some values of the model parameter, while the other mode always remains constant. However, this always occurs formore » unstable solutions which are not attractors for the given potential. The most interesting particular cases of constant-roll inflation remaining viable with the most recent observational data are quadratic hilltop inflation (with cutoff) and natural inflation (with an additional negative cosmological constant). In these cases even-order slow-roll parameters approach non-negligible constants while the odd ones are asymptotically vanishing in the quasi-de Sitter regime.« less

  16. User Manual for the AZ-101 Data Acquisition System (AS-101 DAS)

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

    BRAYTON, D.D.

    2000-02-17

    User manual for the TK AZ-101 Waste Retrieval System Data Acquisition System. The purpose of this document is to describe use of the AZ-101 Data Acquisition System (AZ-101 DAS). The AZ-101 DAS is provided to fulfill the requirements for data collection and monitoring as defined in Letters of Instruction (LOI) from Numatec Hanford Corporation (NHC) to Fluor Federal Services (FFS). For a complete description of the system, including design, please refer to the AZ-101 DAS System Description document, RPP-5572.

  17. Theoretical Evaluation of the Transient Response of Constant Head and Constant Flow-Rate Permeability Tests

    USGS Publications Warehouse

    Zhang, M.; Takahashi, M.; Morin, R.H.; Esaki, T.

    1998-01-01

    A theoretical analysis is presented that compares the response characteristics of the constant head and the constant flowrate (flow pump) laboratory techniques for quantifying the hydraulic properties of geologic materials having permeabilities less than 10-10 m/s. Rigorous analytical solutions that describe the transient distributions of hydraulic gradient within a specimen are developed, and equations are derived for each method. Expressions simulating the inflow and outflow rates across the specimen boundaries during a constant-head permeability test are also presented. These solutions illustrate the advantages and disadvantages of each method, including insights into measurement accuracy and the validity of using Darcy's law under certain conditions. The resulting observations offer practical considerations in the selection of an appropriate laboratory test method for the reliable measurement of permeability in low-permeability geologic materials.

  18. A full set of langatate high-temperature acoustic wave constants: elastic, piezoelectric, dielectric constants up to 900°C.

    PubMed

    Davulis, Peter M; da Cunha, Mauricio Pereira

    2013-04-01

    A full set of langatate (LGT) elastic, dielectric, and piezoelectric constants with their respective temperature coefficients up to 900°C is presented, and the relevance of the dielectric and piezoelectric constants and temperature coefficients are discussed with respect to predicted and measured high-temperature SAW propagation properties. The set of constants allows for high-temperature acoustic wave (AW) propagation studies and device design. The dielectric constants and polarization and conductive losses were extracted by impedance spectroscopy of parallel-plate capacitors. The measured dielectric constants at high temperatures were combined with previously measured LGT expansion coefficients and used to determine the elastic and piezoelectric constants using resonant ultrasound spectroscopy (RUS) measurements at temperatures up to 900°C. The extracted LGT piezoelectric constants and temperature coefficients show that e11 and e14 change by up to 62% and 77%, respectively, for the entire 25°C to 900°C range when compared with room-temperature values. The LGT high-temperature constants and temperature coefficients were verified by comparing measured and predicted phase velocities (vp) and temperature coefficients of delay (TCD) of SAW delay lines fabricated along 6 orientations in the LGT plane (90°, 23°, Ψ) up to 900°C. For the 6 tested orientations, the predicted SAW vp agree within 0.2% of the measured vp on average and the calculated TCD is within 9.6 ppm/°C of the measured value on average over the temperature range of 25°C to 900°C. By including the temperature dependence of both dielectric and piezoelectric constants, the average discrepancies between predicted and measured SAW properties were reduced, on average: 77% for vp, 13% for TCD, and 63% for the turn-over temperatures analyzed.

  19. Wormholes and the cosmological constant problem.

    NASA Astrophysics Data System (ADS)

    Klebanov, I.

    The author reviews the cosmological constant problem and the recently proposed wormhole mechanism for its solution. Summation over wormholes in the Euclidean path integral for gravity turns all the coupling parameters into dynamical variables, sampled from a probability distribution. A formal saddle point analysis results in a distribution with a sharp peak at the cosmological constant equal to zero, which appears to solve the cosmological constant problem. He discusses the instabilities of the gravitational Euclidean path integral and the difficulties with its interpretation. He presents an alternate formalism for baby universes, based on the "third quantization" of the Wheeler-De Witt equation. This approach is analyzed in a minisuperspace model for quantum gravity, where it reduces to simple quantum mechanics. Once again, the coupling parameters become dynamical. Unfortunately, the a priori probability distribution for the cosmological constant and other parameters is typically a smooth function, with no sharp peaks.

  20. Calculation of kinetic rate constants from thermodynamic data

    NASA Technical Reports Server (NTRS)

    Marek, C. John

    1995-01-01

    A new scheme for relating the absolute value for the kinetic rate constant k to the thermodynamic constant Kp is developed for gases. In this report the forward and reverse rate constants are individually related to the thermodynamic data. The kinetic rate constants computed from thermodynamics compare well with the current kinetic rate constants. This method is self consistent and does not have extensive rules. It is first demonstrated and calibrated by computing the HBr reaction from H2 and Br2. This method then is used on other reactions.

  1. Constant-roll (quasi-)linear inflation

    NASA Astrophysics Data System (ADS)

    Karam, A.; Marzola, L.; Pappas, T.; Racioppi, A.; Tamvakis, K.

    2018-05-01

    In constant-roll inflation, the scalar field that drives the accelerated expansion of the Universe is rolling down its potential at a constant rate. Within this framework, we highlight the relations between the Hubble slow-roll parameters and the potential ones, studying in detail the case of a single-field Coleman-Weinberg model characterised by a non-minimal coupling of the inflaton to gravity. With respect to the exact constant-roll predictions, we find that assuming an approximate slow-roll behaviour yields a difference of Δ r = 0.001 in the tensor-to-scalar ratio prediction. Such a discrepancy is in principle testable by future satellite missions. As for the scalar spectral index ns, we find that the existing 2-σ bound constrains the value of the non-minimal coupling to ξphi ~ 0.29–0.31 in the model under consideration.

  2. Equivalent refractive-index structure constant of non-Kolmogorov turbulence.

    PubMed

    Li, Yujie; Zhu, Wenyue; Wu, Xiaoqing; Rao, Ruizhong

    2015-09-07

    The relationship between the non-Kolmogorov refractive-index structure constant and the Kolmogorov refractive-index structure constant is derived by using the refractive-index structure function and the variance of refractive-index fluctuations. It shows that the non-Kolmogorov structure constant is proportional to the Kolmogorov structure constant and the scaling factor depends on the outer scale and the spectral power law. For a fixed Kolmogorov structure constant, the non-Kolmogorov structure constant increases with a increasing outer scale for the power law less than 11/3, the trend is opposite for the power law greater than 11/3. This equivalent relation provides a way of obtaining the non-Kolmogorov structure constant by using the Kolmogorov structure constant.

  3. Systematic harmonic power laws inter-relating multiple fundamental constants

    NASA Astrophysics Data System (ADS)

    Chakeres, Donald; Buckhanan, Wayne; Andrianarijaona, Vola

    2017-01-01

    Power laws and harmonic systems are ubiquitous in physics. We hypothesize that 2, π, the electron, Bohr radius, Rydberg constant, neutron, fine structure constant, Higgs boson, top quark, kaons, pions, muon, Tau, W, and Z when scaled in a common single unit are all inter-related by systematic harmonic powers laws. This implies that if the power law is known it is possible to derive a fundamental constant's scale in the absence of any direct experimental data of that constant. This is true for the case of the hydrogen constants. We created a power law search engine computer program that randomly generated possible positive or negative powers searching when the product of logical groups of constants equals 1, confirming they are physically valid. For 2, π, and the hydrogen constants the search engine found Planck's constant, Coulomb's energy law, and the kinetic energy law. The product of ratios defined by two constants each was the standard general format. The search engine found systematic resonant power laws based on partial harmonic fraction powers of the neutron for all of the constants with products near 1, within their known experimental precision, when utilized with appropriate hydrogen constants. We conclude that multiple fundamental constants are inter-related within a harmonic power law system.

  4. A hundred years with the cosmological constant

    NASA Astrophysics Data System (ADS)

    Grøn, Øyvind G.

    2018-07-01

    The main points in the history of the cosmological constant are briefly discussed. As a conceptual background, useful for teaching of physics at an elementary college and university level, Newton’s theory formulated locally in terms of the Poisson equation is presented, and it is shown how it is modified by the introduction of the cosmological constant. The different physical interpretations of the cosmological constant, as introduced by Einstein in 1917 and interpreted by Lemaître in 1934, are presented. Energy conservation in an expanding universe dominated by vacuum energy is discussed. The connection between the cosmological constant and the quantum mechanical vacuum energy is mentioned, together with the problem that a quantum mechanical calculation of the density of the vacuum energy gives a vastly too large value of the cosmological constant. The article is concluded by reviewing a solution of this problem that was presented on May 11, 2017.

  5. Effect on head-wind profiles and mean head-wind velocity on landing capacity flying constant-airspeed and constant-groundspeed approaches

    NASA Technical Reports Server (NTRS)

    Hastings, E. C., Jr.; Kelley, W. W.

    1979-01-01

    A study was conducted to determine the effect of head-wind profiles and mean head-wind velocities on runway landing capacity for airplanes flying constant-airspeed and constant-groundspeed approaches. It was determined that when the wind profiles were encountered with the currently used constant airspeed approach method, the landing capacity was reduced. The severity of these reductions increased as the mean head-wind value of the profile increased. When constant-groundspeed approaches were made in the same wind profiles, there were no losses in landing capacity. In an analysis of mean head winds, it was determined that in a mean head wind of 35 knots, the landing capacity using constant-airspeed approaches was 13% less than for the no wind condition. There were no reductions in landing capacity with constant-groundspeed approaches for mean head winds less than 35 knots. This same result was observed when the separation intervals between airplanes was reduced.

  6. Automated Microwave Dielectric Constant Measurement

    DTIC Science & Technology

    1987-03-01

    IJSWC TR 86-46 AD.-A 184 182 AUTOMATED MICROWAVE DIELECTRIC CONSTANT MEASUREMENT SYTIEM BY B. C. GLANCY A. KRALL PESEARCH AND TECHNOLOGY DEPARTMENT...NO0. NO. ACCESSION NO. Silver Spring, Maryland 20903-500061152N ZROO1 ZRO131 R1AA29 11. TITLE (Include Security Classification) AUTOMATED MICROWAVE ...constants as a funct on of microwave frequency has been simplified using an automated testing apparatus. This automated procedure is based on the use of a

  7. Reports on Astronomical Constants

    NASA Astrophysics Data System (ADS)

    Fukushima, Toshio

    Recent progress in the determination of astronomical constants is reviewed. By using the latest numerical integration of LC (Irwin and Fukushima, 1999) and the latest value of the geoidal potential W0 (Groten, 1999), we reestimated the general relativistic scale constants as LC = 1.480~826~867~4 × 10-8 ± 1.4 × 10-17, LG = 6.969~290~13 × 10-10 ± 6 × 10-18, and LB = 1.550~519~767~5 × 10-8 ± 2.0 × 10-17. Presented is a proposal to fix the numerical value of LG as the above in order to remove the geophysical ambiguity in its evaluation in the future. Next focused upon is the correction to the IAU 1976 Precession (Lieske et al., 1977). By simply averaging the latest VLBI-based determinations (Mathews et al., 2000; Petrov, 2000; Shirai and Fukushima, 2000; Vondrak and Ron, 2000) and the latest LLR-based determinations (Chapront et al., 1999), we obtained the best estimates of precession-related quantities at J2000.0: the general precession in longitude, p = 5~028.78 ± 0.03 ''/cy; obliquity of the ecliptic, ɛ0 = 23o26'21.''405~6 ± 0.''0005; and the pole offsets of the CEP of ICRS, Δ ψ0 sin ɛ0 = (-17.5 ± 0.8) mas, and Δ ɛ0 = (-5.2 ± 0.4) mas. After quoting the latest determination of mass of Pluto-Charon system (Tholen and Buie, 1997) and the recent change of G (Mohr and Taylor, 1999), proposed is a draft IAU 2000 File of Current Best Estimates of Astronomical Constants to replace the former 1994 version (Standish, 1995). It may even supplant the IAU 1976 System of Astronomical Constants (Duncombe et al., 1977), subject to discussion at this General Assembly.

  8. Weak Acid Ionization Constants and the Determination of Weak Acid-Weak Base Reaction Equilibrium Constants in the General Chemistry Laboratory

    ERIC Educational Resources Information Center

    Nyasulu, Frazier; McMills, Lauren; Barlag, Rebecca

    2013-01-01

    A laboratory to determine the equilibrium constants of weak acid negative weak base reactions is described. The equilibrium constants of component reactions when multiplied together equal the numerical value of the equilibrium constant of the summative reaction. The component reactions are weak acid ionization reactions, weak base hydrolysis…

  9. Dielectric Constant of Undercooled Water.

    DTIC Science & Technology

    1981-09-01

    can or radiation shield, and the experimental stage. The two cans are evacu- -3 ated to about 10 3 mm Hg. The outer can is made of aluminum and is...wrapped with aluminum tubing through which a commercial circulator-cooler pumps a circulating fluid with its tempera- ture controlled to 20 mK between...Control and Measurement System" Strem, R.B., Das, B.K., and Greer, S.C., Rev. Sci. Instrum., in press. 17 Type S-1, Thermometrics , Inc., Ediaon, N.J. 183

  10. Moisture Forecast Bias Correction in GEOS DAS

    NASA Technical Reports Server (NTRS)

    Dee, D.

    1999-01-01

    Data assimilation methods rely on numerous assumptions about the errors involved in measuring and forecasting atmospheric fields. One of the more disturbing of these is that short-term model forecasts are assumed to be unbiased. In case of atmospheric moisture, for example, observational evidence shows that the systematic component of errors in forecasts and analyses is often of the same order of magnitude as the random component. we have implemented a sequential algorithm for estimating forecast moisture bias from rawinsonde data in the Goddard Earth Observing System Data Assimilation System (GEOS DAS). The algorithm is designed to remove the systematic component of analysis errors and can be easily incorporated in an existing statistical data assimilation system. We will present results of initial experiments that show a significant reduction of bias in the GEOS DAS moisture analyses.

  11. Soil-moisture constants and their variation

    Treesearch

    Walter M. Broadfoot; Hubert D. Burke

    1958-01-01

    "Constants" like field capacity, liquid limit, moisture equivalent, and wilting point are used by most students and workers in soil moisture. These constants may be equilibrium points or other values that describe soil moisture. Their values under specific soil and cover conditions have been discussed at length in the literature, but few general analyses and...

  12. Brady's Geothermal Field DAS Earthquake Data

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

    Kurt Feigl

    The submitted data correspond to the vibration caused by a 3.4 M earthquake and captured by the DAS horizontal and vertical arrays during the PoroTomo Experiment. Earthquake information : M 4.3 - 23km ESE of Hawthorne, Nevada Time: 2016-03-21 07:37:10 (UTC) Location: 38.479 N 118.366 W Depth: 9.9 km

  13. Prevalence of mabDAS-1 positivity in biopsy specimens from the esophagogastric junction.

    PubMed

    Rogge-Wolf, Claudia; Seldenrijk, Cornelis A; Das, Kiron M; Timmer, Robin; Breumelhof, Ronald; Smout, André J P M; Amenta, Peter S; Griffel, Louis H

    2002-12-01

    Intestinal metaplasia (IM) is a precursor for malignancies at the esophagogastric junction. A monoclonal antibody, mAbDAS-1, can probably identify cellular characteristics of IM before the appearance of goblet cells. The aim of this study was to examine the prevalence of mAbDAS-1 positivity in biopsies from the squamocolumnar junction (SCJ) and to correlate this positivity with the presence of IM and clinical findings. In 559 patients, reflux symptoms were scored, and the presence of reflux esophagitis and hiatus hernia was evaluated during endoscopy. Two biopsy specimens were obtained from the SCJ. In a subset of patients (n = 99), biopsies from the endoscopically defined cardiac region (2 cm distal to proximal margin of gastric folds) were available. Biopsy specimens were stained with hematoxylin and eosin, Alcian Blue, modified Giemsa, and mAbDAS-1. mAbDAS-1 positivity was observed in the SCJ biopsies of 201 of 486 (41.4%) patients without IM and in 64 of 73 (87.7%) patients with IM. Patients without IM but with antibody positivity showed similar histological characteristics as patients with IM at the SCJ. Biopsies of 123 of 559 patients (22%) revealed a columnar-cuboidal epithelium, which was found to be mAbDAS-1 positive in 64.2% (77 of 123). Tissue specimens from the cardiac region without IM stained positive in 14.2% (13 of 91), 12 of those also stained at the SCJ. In patients without IM, a high prevalence of mAbDAS-1 positivity was observed. Biopsies of these patients showed similar histological characteristics as patients with IM. Although not all patients exhibiting this reactivity may develop IM, mAbDAS-1 reactivity may help in the understanding of the histogenesis of IM at the SCJ.

  14. Diurnal rhythm of the pituitary-adrenocortical response to stress: effect of constant light and constant darkness

    NASA Technical Reports Server (NTRS)

    Vernikos-Danellis, J.; Winget, C. M.; Hetherington, N. W.

    1970-01-01

    The existence of a biological rhythm in the response of animals to noxious stimuli and drugs is well known. However, the mechanism of this response is not well understood. This study was undertaken to describe the existence of a diurnal rhythm in the hypothalamic-pituitary-adrenocortical system before and after stress in female rats kept in controlled environmental conditions in 12L:12D, 24L:OD, or OL:24D. Plasma ACTH and plasma corticosterone concentrations were compared in unstressed animals. The time pattern in the response to stress was determined at four hourly intervals during a 24 hr period in which plasma ACTH and plasma corticosterone were measured at different time intervals. The stress response varied considerably with time of day in both magnitude and duration. The adrenals of rats exposed to constant light for 45 days atrophied, whereas the adrenals of animals kept in constant dark for the same period did not differ significantly from those of controls kept in 12L:12D. The increase in plasma ACTH in response to stress was greater both in the animals maintained in constant light and in constant dark than in the 12L:12D controls. Homeostatic mechanisms involved in these changes are discussed.

  15. Averaging of elastic constants for polycrystals

    DOE PAGES

    Blaschke, Daniel N.

    2017-10-13

    Many materials of interest are polycrystals, i.e., aggregates of single crystals. Randomly distributed orientations of single crystals lead to macroscopically isotropic properties. Here in this paper, we briefly review strategies of calculating effective isotropic second and third order elastic constants from the single crystal ones. Our main emphasis is on single crystals of cubic symmetry. Specifically, the averaging of third order elastic constants has not been particularly successful in the past, and discrepancies have often been attributed to texturing of polycrystals as well as to uncertainties in the measurement of elastic constants of both poly and single crystals. While thismore » may well be true, we also point out here shortcomings in the theoretical averaging framework.« less

  16. Role of endothelium sensitivity to shear stress in noradrenaline-induced constriction of feline femoral arterial bed under constant flow and constant pressure perfusions.

    PubMed

    Kartamyshev, Sergey P; Balashov, Sergey A; Melkumyants, Arthur M

    2007-01-01

    The effect of shear stress at the endothelium in the attenuation of the noradrenaline-induced constriction of the femoral vascular bed perfused at a constant blood flow was investigated in 16 anesthetized cats. It is known that the adrenergic vasoconstriction of the femoral vascular bed is considerably greater at a constant pressure perfusion than at a constant blood flow. This difference may depend on the ability of the endothelium to relax smooth muscle in response to an increase in wall shear stress. Since the shear stress is directly related to the blood flow and inversely related to the third power of vessel diameter, vasoconstriction at a constant blood flow increases the wall shear stress that is the stimulus for smooth muscle relaxation opposing constriction. On the other hand, at a constant perfusion pressure, vasoconstriction is accompanied by a decrease in flow rate, which prevents a wall shear stress increase. To reveal the effect of endothelial sensitivity to shear stress, we compared noradrenaline-induced changes in total and proximal arterial resistances during perfusion of the hind limb at a constant blood flow and at a constant pressure in vessels with intact and injured endothelium. We found that in the endothelium-intact bed the same concentration of noradrenaline at a constant flow caused an increase in overall vascular peripheral resistance that was half as large as at a constant perfusion pressure. This difference is mainly confined to the proximal arterial vessels (arteries and large arterioles) whose resistance at a constant flow increased only 0.19 +/- 0.03 times compared to that at a constant pressure. The removal of the endothelium only slightly increased constrictor responses at the perfusion under a constant pressure (noradrenaline-induced increases of both overall and proximal arterial resistance augmented by 12%), while the responses of the proximal vessels at a constant flow became 4.7 +/- 0.4 times greater than in the endothelium

  17. Cosmological Constant: A Lesson from Bose-Einstein Condensates

    NASA Astrophysics Data System (ADS)

    Finazzi, Stefano; Liberati, Stefano; Sindoni, Lorenzo

    2012-02-01

    The cosmological constant is one of the most pressing problems in modern physics. We address this issue from an emergent gravity standpoint, by using an analogue gravity model. Indeed, the dynamics of the emergent metric in a Bose-Einstein condensate can be described by a Poisson-like equation with a vacuum source term reminiscent of a cosmological constant. The direct computation of this term shows that in emergent gravity scenarios this constant may be naturally much smaller than the naive ground-state energy of the emergent effective field theory. This suggests that a proper computation of the cosmological constant would require a detailed understanding about how Einstein equations emerge from the full microscopic quantum theory. In this light, the cosmological constant appears as a decisive test bench for any quantum or emergent gravity scenario.

  18. Cosmological constant: a lesson from Bose-Einstein condensates.

    PubMed

    Finazzi, Stefano; Liberati, Stefano; Sindoni, Lorenzo

    2012-02-17

    The cosmological constant is one of the most pressing problems in modern physics. We address this issue from an emergent gravity standpoint, by using an analogue gravity model. Indeed, the dynamics of the emergent metric in a Bose-Einstein condensate can be described by a Poisson-like equation with a vacuum source term reminiscent of a cosmological constant. The direct computation of this term shows that in emergent gravity scenarios this constant may be naturally much smaller than the naive ground-state energy of the emergent effective field theory. This suggests that a proper computation of the cosmological constant would require a detailed understanding about how Einstein equations emerge from the full microscopic quantum theory. In this light, the cosmological constant appears as a decisive test bench for any quantum or emergent gravity scenario.

  19. Dynamic Characteristics of The DSI-Type Constant-Flow Valves

    NASA Astrophysics Data System (ADS)

    Kang, Yuan; Hu, Sheng-Yan; Chou, Hsien-Chin; Lee, Hsing-Han

    Constant flow valves have been presented in industrial applications or academic studies, which compensate recess pressures of a hydrostatic bearing to resist load fluctuating. The flow rate of constant-flow valves can be constant in spite of the pressure changes in recesses, however the design parameters must be specified. This paper analyzes the dynamic responses of DSI-type constant-flow valves that is designed as double pistons on both ends of a spool with single feedback of working pressure and regulating restriction at inlet. In this study the static analysis presents the specific relationships among design parameters for constant flow rate and the dynamic analyses give the variations around the constant flow rate as the working pressure fluctuates.

  20. FOREWORD: International determination of the Avogadro constant International determination of the Avogadro constant

    NASA Astrophysics Data System (ADS)

    Massa, Enrico; Nicolaus, Arnold

    2011-04-01

    This issue of Metrologia collects papers about the results of an international research project aimed at the determination of the Avogadro constant, NA, by counting the atoms in a silicon crystal highly enriched with the isotope 28Si. Fifty years ago, Egidi [1] thought about realizing an atomic mass standard. In 1965, Bonse and Hart [2] operated the first x-ray interferometer, thus paving the way to the achievement of Egidi's dream, and soon Deslattes et al [3] completed the first counting of the atoms in a natural silicon crystal. The present project, outlined by Zosi [4] in 1983, began in 2004 by combining the experiences and capabilities of the BIPM, INRIM, IRMM, NIST, NPL, NMIA, NMIJ and PTB. The start signal, ratified by a memorandum of understanding, was a contract for the production of a silicon crystal highly enriched with 28Si. The enrichment process was undertaken by the Central Design Bureau of Machine Building in St Petersburg. Subsequently, a polycrystal was grown in the Institute of Chemistry of High-Purity Substances of the Russian Academy of Sciences in Nizhny Novgorod and a 28Si boule was grown and purified by the Leibniz-Institut für Kristallzüchtung in Berlin. Isotope enrichment made it possible to apply isotope dilution mass spectroscopy, to determine the Avogadro constant with unprecedented accuracy, and to fulfil Egidi's dream. To convey Egidi's 'fantasy' into practice, two 28Si kilogram prototypes shaped as quasi-perfect spheres were manufactured by the Australian Centre for Precision Optics; their isotopic composition, molar mass, mass, volume, density and lattice parameter were accurately determined and their surfaces were chemically and physically characterized at the atomic scale. The paper by Andreas et al reviews the work carried out; it collates all the findings and illustrates how Avogadro's constant was obtained. Impurity concentration and gradients in the enriched crystal were measured by infrared spectroscopy and taken into

  1. Simple constant-current-regulated power supply

    NASA Technical Reports Server (NTRS)

    Priebe, D. H. E.; Sturman, J. C.

    1977-01-01

    Supply incorporates soft-start circuit that slowly ramps current up to set point at turn-on. Supply consists of full-wave rectifier, regulating pass transistor, current feedback circuit, and quad single-supply operational-amplifier circuit providing control. Technique is applicable to any system requiring constant dc current, such as vacuum tube equipment, heaters, or battery charges; it has been used to supply constant current for instrument calibration.

  2. Definition and Measurement of Selection Bias: From Constant Ratio to Constant Difference

    ERIC Educational Resources Information Center

    Cahan, Sorel; Gamliel, Eyal

    2006-01-01

    Despite its intuitive appeal and popularity, Thorndike's constant ratio (CR) model for unbiased selection is inherently inconsistent in "n"-free selection. Satisfaction of the condition for unbiased selection, when formulated in terms of success/acceptance probabilities, usually precludes satisfaction by the converse probabilities of…

  3. Constant-pressure Blowers

    NASA Technical Reports Server (NTRS)

    Sorensen, E

    1940-01-01

    The conventional axial blowers operate on the high-pressure principle. One drawback of this type of blower is the relatively low pressure head, which one attempts to overcome with axial blowers producing very high pressure at a given circumferential speed. The Schicht constant-pressure blower affords pressure ratios considerably higher than those of axial blowers of conventional design with approximately the same efficiency.

  4. Cosmological constant is a conserved charge

    NASA Astrophysics Data System (ADS)

    Chernyavsky, Dmitry; Hajian, Kamal

    2018-06-01

    Cosmological constant can always be considered as the on-shell value of a top form in gravitational theories. The top form is the field strength of a gauge field, and the theory enjoys a gauge symmetry. We show that cosmological constant is the charge of the global part of the gauge symmetry, and is conserved irrespective of the dynamics of the metric and other fields. In addition, we introduce its conjugate chemical potential, and prove the generalized first law of thermodynamics which includes variation of cosmological constant as a conserved charge. We discuss how our new term in the first law is related to the volume–pressure term. In parallel with the seminal Wald entropy, this analysis suggests that pressure can also be considered as a conserved charge.

  5. MiDAS: the field guide to the microbes of activated sludge.

    PubMed

    McIlroy, Simon Jon; Saunders, Aaron Marc; Albertsen, Mads; Nierychlo, Marta; McIlroy, Bianca; Hansen, Aviaja Anna; Karst, Søren Michael; Nielsen, Jeppe Lund; Nielsen, Per Halkjær

    2015-01-01

    The Microbial Database for Activated Sludge (MiDAS) field guide is a freely available online resource linking the identity of abundant and process critical microorganisms in activated sludge wastewater treatment systems to available data related to their functional importance. Phenotypic properties of some of these genera are described, but most are known only from sequence data. The MiDAS taxonomy is a manual curation of the SILVA taxonomy that proposes a name for all genus-level taxa observed to be abundant by large-scale 16 S rRNA gene amplicon sequencing of full-scale activated sludge communities. The taxonomy can be used to classify unknown sequences, and the online MiDAS field guide links the identity to the available information about their morphology, diversity, physiology and distribution. The use of a common taxonomy across the field will provide a solid foundation for the study of microbial ecology of the activated sludge process and related treatment processes. The online MiDAS field guide is a collaborative workspace intended to facilitate a better understanding of the ecology of activated sludge and related treatment processes--knowledge that will be an invaluable resource for the optimal design and operation of these systems. © The Author(s) 2015. Published by Oxford University Press.

  6. MiDAS: the field guide to the microbes of activated sludge

    PubMed Central

    McIlroy, Simon Jon; Saunders, Aaron Marc; Albertsen, Mads; Nierychlo, Marta; McIlroy, Bianca; Hansen, Aviaja Anna; Karst, Søren Michael; Nielsen, Jeppe Lund; Nielsen, Per Halkjær

    2015-01-01

    The Microbial Database for Activated Sludge (MiDAS) field guide is a freely available online resource linking the identity of abundant and process critical microorganisms in activated sludge wastewater treatment systems to available data related to their functional importance. Phenotypic properties of some of these genera are described, but most are known only from sequence data. The MiDAS taxonomy is a manual curation of the SILVA taxonomy that proposes a name for all genus-level taxa observed to be abundant by large-scale 16 S rRNA gene amplicon sequencing of full-scale activated sludge communities. The taxonomy can be used to classify unknown sequences, and the online MiDAS field guide links the identity to the available information about their morphology, diversity, physiology and distribution. The use of a common taxonomy across the field will provide a solid foundation for the study of microbial ecology of the activated sludge process and related treatment processes. The online MiDAS field guide is a collaborative workspace intended to facilitate a better understanding of the ecology of activated sludge and related treatment processes—knowledge that will be an invaluable resource for the optimal design and operation of these systems. Database URL: http://www.midasfieldguide.org PMID:26120139

  7. Influences of brain tissue poroelastic constants on intracranial pressure (ICP) during constant-rate infusion.

    PubMed

    Li, Xiaogai; von Holst, Hans; Kleiven, Svein

    2013-01-01

    A 3D finite element (FE) model has been developed to study the mean intracranial pressure (ICP) response during constant-rate infusion using linear poroelasticity. Due to the uncertainties in the poroelastic constants for brain tissue, the influence of each of the main parameters on the transient ICP infusion curve was studied. As a prerequisite for transient analysis, steady-state simulations were performed first. The simulated steady-state pressure distribution in the brain tissue for a normal cerebrospinal fluid (CSF) circulation system showed good correlation with experiments from the literature. Furthermore, steady-state ICP closely followed the infusion experiments at different infusion rates. The verified steady-state models then served as a baseline for the subsequent transient models. For transient analysis, the simulated ICP shows a similar tendency to that found in the experiments, however, different values of the poroelastic constants have a significant effect on the infusion curve. The influence of the main poroelastic parameters including the Biot coefficient α, Skempton coefficient B, drained Young's modulus E, Poisson's ratio ν, permeability κ, CSF absorption conductance C(b) and external venous pressure p(b) was studied to investigate the influence on the pressure response. It was found that the value of the specific storage term S(ε) is the dominant factor that influences the infusion curve, and the drained Young's modulus E was identified as the dominant parameter second to S(ε). Based on the simulated infusion curves from the FE model, artificial neural network (ANN) was used to find an optimised parameter set that best fit the experimental curve. The infusion curves from both the FE simulation and using ANN confirmed the limitation of linear poroelasticity in modelling the transient constant-rate infusion.

  8. Space Shuttle astrodynamical constants

    NASA Technical Reports Server (NTRS)

    Cockrell, B. F.; Williamson, B.

    1978-01-01

    Basic space shuttle astrodynamic constants are reported for use in mission planning and construction of ground and onboard software input loads. The data included here are provided to facilitate the use of consistent numerical values throughout the project.

  9. The Conformal Factor and the Cosmological Constant

    NASA Astrophysics Data System (ADS)

    Giddings, Steven B.

    The issue of the conformal factor in quantum gravity is examined for Lorentzian signature spacetimes. In Euclidean signature, the “wrong” sign of the conformal action makes the path integral undefined, but in Lorentzian signature this sign is tied to the instability of gravity and once this is accounted for the path integral should be well-defined. In this approach it is not obvious that the Baum-Hawking-Coleman mechanism for suppression of the cosmological constant functions. It is conceivable that since the multiuniverse system exhibits an instability for positive cosmological constant, the dynamics should force the system to zero cosmological constant.

  10. Dynamical approach to the cosmological constant.

    PubMed

    Mukohyama, Shinji; Randall, Lisa

    2004-05-28

    We consider a dynamical approach to the cosmological constant. There is a scalar field with a potential whose minimum occurs at a generic, but negative, value for the vacuum energy, and it has a nonstandard kinetic term whose coefficient diverges at zero curvature as well as the standard kinetic term. Because of the divergent coefficient of the kinetic term, the lowest energy state is never achieved. Instead, the cosmological constant automatically stalls at or near zero. The merit of this model is that it is stable under radiative corrections and leads to stable dynamics, despite the singular kinetic term. The model is not complete, however, in that some reheating is required. Nonetheless, our approach can at the very least reduce fine-tuning by 60 orders of magnitude or provide a new mechanism for sampling possible cosmological constants and implementing the anthropic principle.

  11. Constant voltage and constant current control implementation for electric vehicles (evs) wireless charger

    NASA Astrophysics Data System (ADS)

    Tampubolon, Marojahan; Pamungkas, Laskar; Hsieh, Yao Ching; Chiu, Huang Jen

    2018-04-01

    This paper presents the implementation of Constant Voltage (CV) and Constant Current (CC) control for a wireless charger system. A battery charging system needs these control modes to ensure the safety of the battery and the effectiveness of the charging system. Here, the wireless charger system does not employ any post-regulator stage to control the output voltage and output current of the charger. But, it uses a variable frequency control incorporated with a conventional PI control. As a result, the size and the weight of the system are reduced. This paper discusses the brief review of the SS-WPT, control strategy and implementation of the CV and CC control. Experimental hardware with 2kW output power has been performed and tested. The results show that the proposed CV and CC control method works well with the system.

  12. Asymptotically Vanishing Cosmological Constant in the Multiverse

    NASA Astrophysics Data System (ADS)

    Kawai, Hikaru; Okada, Takashi

    We study the problem of the cosmological constant in the context of the multiverse in Lorentzian space-time, and show that the cosmological constant will vanish in the future. This sort of argument was started by Sidney Coleman in 1989, and he argued that the Euclidean wormholes make the multiverse partition function a superposition of various values of the cosmological constant Λ, which has a sharp peak at Λ = 0. However, the implication of the Euclidean analysis to our Lorentzian space-time is unclear. With this motivation, we analyze the quantum state of the multiverse in Lorentzian space-time by the WKB method, and calculate the density matrix of our universe by tracing out the other universes. Our result predicts vanishing cosmological constant. While Coleman obtained the enhancement at Λ = 0 through the action itself, in our Lorentzian analysis the similar enhancement arises from the front factor of eiS in the universe wave function, which is in the next leading order in the WKB approximation.

  13. Dereplication, Aggregation and Scoring Tool (DAS Tool) v1.0

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

    SIEBER, CHRISTIAN

    Communities of uncultivated microbes are critical to ecosystem function and microorganism health, and a key objective of metagenomic studies is to analyze organism-specific metabolic pathways and reconstruct community interaction networks. This requires accurate assignment of genes to genomes, yet existing binning methods often fail to predict a reasonable number of genomes and report many bins of low quality and completeness. Furthermore, the performance of existing algorithms varies between samples and biotypes. Here, we present a dereplication, aggregation and scoring strategy, DAS Tool, that combines the strengths of a flexible set of established binning algorithms. DAS Tools applied to a constructedmore » community generated more accurate bins than any automated method. Further, when applied to samples of different complexity, including soil, natural oil seeps, and the human gut, DAS Tool recovered substantially more near-complete genomes than any single binning method alone. Included were three genomes from a novel lineage . The ability to reconstruct many near-complete genomes from metagenomics data will greatly advance genome-centric analyses of ecosystems.« less

  14. Comparing otoacoustic emissions evoked by chirp transients with constant absorbed sound power and constant incident pressure magnitude.

    PubMed

    Keefe, Douglas H; Feeney, M Patrick; Hunter, Lisa L; Fitzpatrick, Denis F

    2017-01-01

    Human ear-canal properties of transient acoustic stimuli are contrasted that utilize measured ear-canal pressures in conjunction with measured acoustic pressure reflectance and admittance. These data are referenced to the tip of a probe snugly inserted into the ear canal. Promising procedures to calibrate across frequency include stimuli with controlled levels of incident pressure magnitude, absorbed sound power, and forward pressure magnitude. An equivalent pressure at the eardrum is calculated from these measured data using a transmission-line model of ear-canal acoustics parameterized by acoustically estimated ear-canal area at the probe tip and length between the probe tip and eardrum. Chirp stimuli with constant incident pressure magnitude and constant absorbed sound power across frequency were generated to elicit transient-evoked otoacoustic emissions (TEOAEs), which were measured in normal-hearing adult ears from 0.7 to 8 kHz. TEOAE stimuli had similar peak-to-peak equivalent sound pressure levels across calibration conditions. Frequency-domain TEOAEs were compared using signal level, signal-to-noise ratio (SNR), coherence synchrony modulus (CSM), group delay, and group spread. Time-domain TEOAEs were compared using SNR, CSM, instantaneous frequency and instantaneous bandwidth. Stimuli with constant incident pressure magnitude or constant absorbed sound power across frequency produce generally similar TEOAEs up to 8 kHz.

  15. Dielectric-constant gas thermometry

    NASA Astrophysics Data System (ADS)

    Gaiser, Christof; Zandt, Thorsten; Fellmuth, Bernd

    2015-10-01

    The principles, techniques and results from dielectric-constant gas thermometry (DCGT) are reviewed. Primary DCGT with helium has been used for measuring T-T90 below the triple point of water (TPW), where T is the thermodynamic temperature and T90 is the temperature on the international temperature scale of 1990 (ITS-90), and, in an inverse regime with T as input quantity, for determining the Boltzmann constant at the TPW. Furthermore, DCGT allows the determination of several important material properties including the polarizability of neon and argon as well as the virial coefficients of helium, neon, and argon. With interpolating DCGT (IDCGT), the ITS-90 has been approximated in the temperature range from 4 K to 25 K. An overview and uncertainty budget for each of these applications of DCGT is provided, accompanied by corroborating evidence from the literature or, for IDCGT, a CIPM key comparison.

  16. Higher success rate with transcranial electrical stimulation of motor-evoked potentials using constant-voltage stimulation compared with constant-current stimulation in patients undergoing spinal surgery.

    PubMed

    Shigematsu, Hideki; Kawaguchi, Masahiko; Hayashi, Hironobu; Takatani, Tsunenori; Iwata, Eiichiro; Tanaka, Masato; Okuda, Akinori; Morimoto, Yasuhiko; Masuda, Keisuke; Tanaka, Yuu; Tanaka, Yasuhito

    2017-10-01

    During spine surgery, the spinal cord is electrophysiologically monitored via transcranial electrical stimulation of motor-evoked potentials (TES-MEPs) to prevent injury. Transcranial electrical stimulation of motor-evoked potential involves the use of either constant-current or constant-voltage stimulation; however, there are few comparative data available regarding their ability to adequately elicit compound motor action potentials. We hypothesized that the success rates of TES-MEP recordings would be similar between constant-current and constant-voltage stimulations in patients undergoing spine surgery. The objective of this study was to compare the success rates of TES-MEP recordings between constant-current and constant-voltage stimulation. This is a prospective, within-subject study. Data from 100 patients undergoing spinal surgery at the cervical, thoracic, or lumbar level were analyzed. The success rates of the TES-MEP recordings from each muscle were examined. Transcranial electrical stimulation with constant-current and constant-voltage stimulations at the C3 and C4 electrode positions (international "10-20" system) was applied to each patient. Compound muscle action potentials were bilaterally recorded from the abductor pollicis brevis (APB), deltoid (Del), abductor hallucis (AH), tibialis anterior (TA), gastrocnemius (GC), and quadriceps (Quad) muscles. The success rates of the TES-MEP recordings from the right Del, right APB, bilateral Quad, right TA, right GC, and bilateral AH muscles were significantly higher using constant-voltage stimulation than those using constant-current stimulation. The overall success rates with constant-voltage and constant-current stimulations were 86.3% and 68.8%, respectively (risk ratio 1.25 [95% confidence interval: 1.20-1.31]). The success rates of TES-MEP recordings were higher using constant-voltage stimulation compared with constant-current stimulation in patients undergoing spinal surgery. Copyright © 2017

  17. GenExp: an interactive web-based genomic DAS client with client-side data rendering.

    PubMed

    Gel Moreno, Bernat; Messeguer Peypoch, Xavier

    2011-01-01

    The Distributed Annotation System (DAS) offers a standard protocol for sharing and integrating annotations on biological sequences. There are more than 1000 DAS sources available and the number is steadily increasing. Clients are an essential part of the DAS system and integrate data from several independent sources in order to create a useful representation to the user. While web-based DAS clients exist, most of them do not have direct interaction capabilities such as dragging and zooming with the mouse. Here we present GenExp, a web based and fully interactive visual DAS client. GenExp is a genome oriented DAS client capable of creating informative representations of genomic data zooming out from base level to complete chromosomes. It proposes a novel approach to genomic data rendering and uses the latest HTML5 web technologies to create the data representation inside the client browser. Thanks to client-side rendering most position changes do not need a network request to the server and so responses to zooming and panning are almost immediate. In GenExp it is possible to explore the genome intuitively moving it with the mouse just like geographical map applications. Additionally, in GenExp it is possible to have more than one data viewer at the same time and to save the current state of the application to revisit it later on. GenExp is a new interactive web-based client for DAS and addresses some of the short-comings of the existing clients. It uses client-side data rendering techniques resulting in easier genome browsing and exploration. GenExp is open source under the GPL license and it is freely available at http://gralggen.lsi.upc.edu/recerca/genexp.

  18. GenExp: An Interactive Web-Based Genomic DAS Client with Client-Side Data Rendering

    PubMed Central

    Gel Moreno, Bernat; Messeguer Peypoch, Xavier

    2011-01-01

    Background The Distributed Annotation System (DAS) offers a standard protocol for sharing and integrating annotations on biological sequences. There are more than 1000 DAS sources available and the number is steadily increasing. Clients are an essential part of the DAS system and integrate data from several independent sources in order to create a useful representation to the user. While web-based DAS clients exist, most of them do not have direct interaction capabilities such as dragging and zooming with the mouse. Results Here we present GenExp, a web based and fully interactive visual DAS client. GenExp is a genome oriented DAS client capable of creating informative representations of genomic data zooming out from base level to complete chromosomes. It proposes a novel approach to genomic data rendering and uses the latest HTML5 web technologies to create the data representation inside the client browser. Thanks to client-side rendering most position changes do not need a network request to the server and so responses to zooming and panning are almost immediate. In GenExp it is possible to explore the genome intuitively moving it with the mouse just like geographical map applications. Additionally, in GenExp it is possible to have more than one data viewer at the same time and to save the current state of the application to revisit it later on. Conclusions GenExp is a new interactive web-based client for DAS and addresses some of the short-comings of the existing clients. It uses client-side data rendering techniques resulting in easier genome browsing and exploration. GenExp is open source under the GPL license and it is freely available at http://gralggen.lsi.upc.edu/recerca/genexp. PMID:21750706

  19. When is the growth index constant?

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

    Polarski, David; Starobinsky, Alexei A.; Giacomini, Hector, E-mail: david.polarski@umontpellier.fr, E-mail: alstar@landau.ac.ru, E-mail: hector.giacomini@lmpt.univ-tours.fr

    The growth index γ is an interesting tool to assess the phenomenology of dark energy (DE) models, in particular of those beyond general relativity (GR). We investigate the possibility for DE models to allow for a constant γ during the entire matter and DE dominated stages. It is shown that if DE is described by quintessence (a scalar field minimally coupled to gravity), this behaviour of γ is excluded either because it would require a transition to a phantom behaviour at some finite moment of time, or, in the case of tracking DE at the matter dominated stage, because themore » relative matter density Ω {sub m} appears to be too small. An infinite number of solutions, with Ω {sub m} and γ both constant, are found with w {sub DE} = 0 corresponding to Einstein-de Sitter universes. For all modified gravity DE models satisfying G {sub eff} ≥ G , among them the f ( R ) DE models suggested in the literature, the condition to have a constant w {sub DE} is strongly violated at the present epoch. In contrast, DE tracking dust-like matter deep in the matter era, but with Ω {sub m} <1, requires G {sub eff} > G and an example is given using scalar-tensor gravity for a range of admissible values of γ. For constant w {sub DE} inside GR, departure from a quasi-constant value is limited until today. Even a large variation of w {sub DE} may not result in a clear signature in the change of γ. The change however is substantial in the future and the asymptotic value of γ is found while its slope with respect to Ω {sub m} (and with respect to z ) diverges and tends to −∞.« less

  20. A New Physical Constant And Its Importance To Energy Production

    NASA Astrophysics Data System (ADS)

    Angus, Andrew

    2003-03-01

    The purpose of this paper is to introduce a new physical constant symbolized by the Greek letter lambda. This paper explains how the new physical constant was derived. This paper also explains the significance of the new physical constant as an alternative explanation to Einstein's Law of Photoelectric Effect. The new physical constant leads to a deeper understanding of the nature of the photon. Furthermore, this new physical constant leads us to the existence of two types of photon, the Planck photon and the Angus photon. Finally, the author also explains the importance of this new physical constant in energy production.

  1. On multisoliton solutions of the constant astigmatism equation

    NASA Astrophysics Data System (ADS)

    Hlaváč, Adam

    2015-09-01

    We introduce an algebraic formula producing infinitely many exact solutions of the constant astigmatism equation {z}{yy}+{(1/z)}{xx}+2=0 from a given seed. A construction of corresponding surfaces of constant astigmatism is then a matter of routine. As a special case, we consider multisoliton solutions of the constant astigmatism equation defined as counterparts of famous multisoliton solutions of the sine-Gordon equation. A few particular examples are surveyed as well.

  2. 40 CFR 86.519-90 - Constant volume sampler calibration.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 19 2013-07-01 2013-07-01 false Constant volume sampler calibration... Regulations for 1978 and Later New Motorcycles; Test Procedures § 86.519-90 Constant volume sampler calibration. (a) The CVS (Constant Volume Sampler) is calibrated using an accurate flowmeter and restrictor...

  3. 40 CFR 86.519-90 - Constant volume sampler calibration.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 19 2012-07-01 2012-07-01 false Constant volume sampler calibration... Regulations for 1978 and Later New Motorcycles; Test Procedures § 86.519-90 Constant volume sampler calibration. (a) The CVS (Constant Volume Sampler) is calibrated using an accurate flowmeter and restrictor...

  4. 40 CFR 86.519-90 - Constant volume sampler calibration.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 18 2011-07-01 2011-07-01 false Constant volume sampler calibration... Regulations for 1978 and Later New Motorcycles; Test Procedures § 86.519-90 Constant volume sampler calibration. (a) The CVS (Constant Volume Sampler) is calibrated using an accurate flowmeter and restrictor...

  5. 40 CFR 86.519-90 - Constant volume sampler calibration.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 19 2014-07-01 2014-07-01 false Constant volume sampler calibration... Regulations for 1978 and Later New Motorcycles; Test Procedures § 86.519-90 Constant volume sampler calibration. (a) The CVS (Constant Volume Sampler) is calibrated using an accurate flowmeter and restrictor...

  6. 40 CFR 86.519-90 - Constant volume sampler calibration.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 18 2010-07-01 2010-07-01 false Constant volume sampler calibration... Regulations for 1978 and Later New Motorcycles; Test Procedures § 86.519-90 Constant volume sampler calibration. (a) The CVS (Constant Volume Sampler) is calibrated using an accurate flowmeter and restrictor...

  7. Rate Constants and Mechanisms of Protein–Ligand Binding

    PubMed Central

    Pang, Xiaodong; Zhou, Huan-Xiang

    2017-01-01

    Whereas protein–ligand binding affinities have long-established prominence, binding rate constants and binding mechanisms have gained increasing attention in recent years. Both new computational methods and new experimental techniques have been developed to characterize the latter properties. It is now realized that binding mechanisms, like binding rate constants, can and should be quantitatively determined. In this review, we summarize studies and synthesize ideas on several topics in the hope of providing a coherent picture of and physical insight into binding kinetics. The topics include microscopic formulation of the kinetic problem and its reduction to simple rate equations; computation of binding rate constants; quantitative determination of binding mechanisms; and elucidation of physical factors that control binding rate constants and mechanisms. PMID:28375732

  8. Wall of fundamental constants

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

    Olive, Keith A.; School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota, 55455; Peloso, Marco

    2011-02-15

    We consider the signatures of a domain wall produced in the spontaneous symmetry breaking involving a dilatonlike scalar field coupled to electromagnetism. Domains on either side of the wall exhibit slight differences in their respective values of the fine-structure constant, {alpha}. If such a wall is present within our Hubble volume, absorption spectra at large redshifts may or may not provide a variation in {alpha} relative to the terrestrial value, depending on our relative position with respect to the wall. This wall could resolve the contradiction between claims of a variation of {alpha} based on Keck/Hires data and of themore » constancy of {alpha} based on Very Large Telescope data. We derive the properties of the wall and the parameters of the underlying microscopic model required to reproduce the possible spatial variation of {alpha}. We discuss the constraints on the existence of the low-energy domain wall and describe its observational implications concerning the variation of the fundamental constants.« less

  9. Diffusion constant of slowly rotating black three-brane

    NASA Astrophysics Data System (ADS)

    Amoozad, Z.; Sadeghi, J.

    2018-01-01

    In this paper, we take the slowly rotating black three-brane background and perturb it by introducing a vector gauge field. We find the components of the gauge field through Maxwell equations and Bianchi identities. Using currents and some ansatz we find Fick's first law at long wavelength regime. An interesting result for this non-trivial supergravity background is that the diffusion constant on the stretched horizon which emerges from Fick's first law is a complex constant. The pure imaginary part of the diffusion constant appears because the black three-brane has angular momentum. By taking the static limit of the corresponding black brane the well known diffusion constant will be recovered. On the other hand, from the point of view of the Fick's second law, we have the dispersion relation ω = - iDq2 and we found a damping of hydrodynamical flow in the holographically dual theory. Existence of imaginary term in the diffusion constant introduces an oscillating propagation of the gauge field in the dual field theory.

  10. Calculation of individual isotope equilibrium constants for geochemical reactions

    USGS Publications Warehouse

    Thorstenson, D.C.; Parkhurst, D.L.

    2004-01-01

    Theory is derived from the work of Urey (Urey H. C. [1947] The thermodynamic properties of isotopic substances. J. Chem. Soc. 562-581) to calculate equilibrium constants commonly used in geochemical equilibrium and reaction-transport models for reactions of individual isotopic species. Urey showed that equilibrium constants of isotope exchange reactions for molecules that contain two or more atoms of the same element in equivalent positions are related to isotope fractionation factors by ?? = (Kex)1/n, where n is the number of atoms exchanged. This relation is extended to include species containing multiple isotopes, for example 13C16O18O and 1H2H18O. The equilibrium constants of the isotope exchange reactions can be expressed as ratios of individual isotope equilibrium constants for geochemical reactions. Knowledge of the equilibrium constant for the dominant isotopic species can then be used to calculate the individual isotope equilibrium constants. Individual isotope equilibrium constants are calculated for the reaction CO2g = CO2aq for all species that can be formed from 12C, 13C, 16O, and 18O; for the reaction between 12C18 O2aq and 1H218Ol; and among the various 1H, 2H, 16O, and 18O species of H2O. This is a subset of a larger number of equilibrium constants calculated elsewhere (Thorstenson D. C. and Parkhurst D. L. [2002] Calculation of individual isotope equilibrium constants for implementation in geochemical models. Water-Resources Investigation Report 02-4172. U.S. Geological Survey). Activity coefficients, activity-concentration conventions for the isotopic variants of H2O in the solvent 1H216Ol, and salt effects on isotope fractionation have been included in the derivations. The effects of nonideality are small because of the chemical similarity of different isotopic species of the same molecule or ion. The temperature dependence of the individual isotope equilibrium constants can be calculated from the temperature dependence of the fractionation

  11. Hamaker constants of iron oxide nanoparticles.

    PubMed

    Faure, Bertrand; Salazar-Alvarez, German; Bergström, Lennart

    2011-07-19

    The Hamaker constants for iron oxide nanoparticles in various media have been calculated using Lifshitz theory. Expressions for the dielectric responses of three iron oxide phases (magnetite, maghemite, and hematite) were derived from recently published optical data. The nonretarded Hamaker constants for the iron oxide nanoparticles interacting across water, A(1w1) = 33 - 39 zJ, correlate relatively well with previous reports, whereas the calculated values in nonpolar solvents (hexane and toluene), A(131) = 9 - 29 zJ, are much lower than the previous estimates, particularly for magnetite. The magnitude of van der Waals interactions varies significantly between the studied phases (magnetite < maghemite < hematite), which highlights the importance of a thorough characterization of the particles. The contribution of magnetic dispersion interactions for particle sizes in the superparamagnetic regime was found to be negligible. Previous conjectures related to colloidal stability and self-assembly have been revisited on the basis of the new Lifshitz values of the Hamaker constants.

  12. Reisen im freien Fall - Teil 2: Das Zwillingsparadoxon aus dem Blickwinkel der ART

    NASA Astrophysics Data System (ADS)

    Sonne, Bernd; Weiß, Reinhard

    2013-07-01

    Nachdem wir uns mit den Prinzipien der ART und einigen Beispielen vertraut gemacht haben, kommen wir nun zur Berechnung des Zwillingsparadoxons aus Sicht des reisenden Zwillings. Dabei spielt das Äquivalenzprinzip eine große Rolle. Deshalb wird die Bewegungssituation noch einmal erläutert, diesmal aus Sicht von Katrin. Sie befindet sich in ihrem System S'in Ruhe. In ihrem System läuft die Zeit t'ab. Nach dem Start fühlt Katrin jedoch eine Kraft, die sie als Gravitationskraft interpretieren kann. Sie merkt es daran, dass sie in den Sitz gedrückt wird. Nach einiger Zeit werden die Triebwerke abgeschaltet, und das Raumschiff fliegt mit konstanter Geschwindigkeit weiter, Phase 2. Anschließend wird der Schub der Triebwerke solange umgekehrt, bis das Raumschiff irgendwo mit der Geschwindigkeit null am Umkehrpunkt U landet, Phase 3 (Abb. 15.1). Die Erde, auf der sich Michael befindet, bewegt sich mit x'(t') aus Sicht von Katrin im freien Fall von ihr weg, s. das Experiment mit dem steigenden Fahrstuhl in Abschn. 13.2.1.

  13. Dielectric constant of liquid alkanes and hydrocarbon mixtures

    NASA Technical Reports Server (NTRS)

    Sen, A. D.; Anicich, V. G.; Arakelian, T.

    1992-01-01

    The complex dielectric constants of n-alkanes with two to seven carbon atoms have been measured. The measurements were conducted using a slotted-line technique at 1.2 GHz and at atmospheric pressure. The temperature was varied from the melting point to the boiling point of the respective alkanes. The real part of the dielectric constant was found to decrease with increasing temperature and correlate with the change in the molar volume. An upper limit to all the loss tangents was established at 0.001. The complex dielectric constants of a few mixtures of liquid alkanes were also measured at room temperature. For a pentane-octane mixture the real part of the dielectric constant could be explained by the Clausius-Mosotti theory. For the mixtures of n-hexane-ethylacetate and n-hexane-acetone the real part of the dielectric constants could be explained by the Onsager theory extended to mixtures. The dielectric constant of the n-hexane-acetone mixture displayed deviations from the Onsager theory at the highest fractions of acetone. The dipole moments of ethylacetate and acetone were determined for dilute mixtures using the Onsager theory and were found to be in agreement with their accepted gas-phase values. The loss tangents of the mixtures exhibited a linear relationship with the volume fraction for low concentrations of the polar liquids.

  14. Biodegradation testing of chemicals with high Henry's constants - Separating mass and effective concentration reveals higher rate constants.

    PubMed

    Birch, Heidi; Andersen, Henrik R; Comber, Mike; Mayer, Philipp

    2017-05-01

    During simulation-type biodegradation tests, volatile chemicals will continuously partition between water phase and headspace. This study addressed how (1) this partitioning affects test results and (2) can be accounted for by combining equilibrium partition and dynamic biodegradation models. An aqueous mixture of 9 (semi)volatile chemicals was first generated using passive dosing and then diluted with environmental surface water producing concentrations in the ng/L to μg/L range. After incubation for 2 h to 4 weeks, automated Headspace Solid Phase Microextraction (HS-SPME) was applied directly on the test systems to measure substrate depletion by biodegradation relatively to abiotic controls. HS-SPME was also applied to determine air to water partitioning ratios. Biodegradation rate constants relating to the chemical in the water phase, k water , were generally a factor 1 to 11 times higher than biodegradation rate constants relating to the total mass of chemical in the test system, k system , with one exceptional factor of 72 times for a long chain alkane. True water phase degradation rate constants were found (i) more appropriate for risk assessment than test system rate constants, (ii) to facilitate extrapolation to other air-water systems and (iii) to be better defined input parameters for aquatic exposure and fate models. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Comparing otoacoustic emissions evoked by chirp transients with constant absorbed sound power and constant incident pressure magnitude

    PubMed Central

    Keefe, Douglas H.; Feeney, M. Patrick; Hunter, Lisa L.; Fitzpatrick, Denis F.

    2017-01-01

    Human ear-canal properties of transient acoustic stimuli are contrasted that utilize measured ear-canal pressures in conjunction with measured acoustic pressure reflectance and admittance. These data are referenced to the tip of a probe snugly inserted into the ear canal. Promising procedures to calibrate across frequency include stimuli with controlled levels of incident pressure magnitude, absorbed sound power, and forward pressure magnitude. An equivalent pressure at the eardrum is calculated from these measured data using a transmission-line model of ear-canal acoustics parameterized by acoustically estimated ear-canal area at the probe tip and length between the probe tip and eardrum. Chirp stimuli with constant incident pressure magnitude and constant absorbed sound power across frequency were generated to elicit transient-evoked otoacoustic emissions (TEOAEs), which were measured in normal-hearing adult ears from 0.7 to 8 kHz. TEOAE stimuli had similar peak-to-peak equivalent sound pressure levels across calibration conditions. Frequency-domain TEOAEs were compared using signal level, signal-to-noise ratio (SNR), coherence synchrony modulus (CSM), group delay, and group spread. Time-domain TEOAEs were compared using SNR, CSM, instantaneous frequency and instantaneous bandwidth. Stimuli with constant incident pressure magnitude or constant absorbed sound power across frequency produce generally similar TEOAEs up to 8 kHz. PMID:28147608

  16. Temperature Dependence Of Elastic Constants Of Polymers

    NASA Technical Reports Server (NTRS)

    Simha, Robert; Papazoglou, Elisabeth

    1989-01-01

    Two papers extend theory of elastic constants of disordered solids to finite temperatures below glass-transition temperatures. First paper, entitled "Elastic Constants of Disordered Solids II: Temperature Dependence," applies to cryogenic temperatures. Second paper, entitled "Theory of Thermoelastic Properties for Polymer Glasses," develops unified treatment for static compressional and elongational properties at temperatures up to glass-transition temperatures.

  17. Das Prinzip Bewegung - Herz und Gehirn als Metaphern des menschlichen Lebens

    NASA Astrophysics Data System (ADS)

    Otis, Laura

    In diesem Jahr, in dem wir Charles Darwins gedenken, möchte ich etwas riskieren und eine Frage erörtern, die für die Literatur ebenso wie für die Biologie zentral ist: Was ist das Leben? Die Antwort auf diese Frage finden wir nicht in der Bibliothek und nicht im Labor, zumindest nicht an diesen erkenntnisproduzierenden Stellen allein. Als Literaturwissenschaftlerin und ehemalige Naturwissenschaftlerin glaube ich, dass wir das Leben nur verstehen werden, wenn wir seinen Wirkungen überall nachforschen, inklusive in der Literatur.

  18. Experimental determination of the effective strong coupling constant

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

    Alexandre Deur; Volker Burkert; Jian-Ping Chen

    2007-07-01

    We extract an effective strong coupling constant from low Q{sup 2} data on the Bjorken sum. Using sum rules, we establish its Q{sup 2}-behavior over the complete Q{sup 2}-range. The result is compared to effective coupling constants extracted from different processes and to calculations based on Schwinger-Dyson equations, hadron spectroscopy or lattice QCD. Although the connection between the experimentally extracted effective coupling constant and the calculations is not clear, the results agree surprisingly well.

  19. Cosmological constant in scale-invariant theories

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

    Foot, Robert; Kobakhidze, Archil; Volkas, Raymond R.

    2011-10-01

    The incorporation of a small cosmological constant within radiatively broken scale-invariant models is discussed. We show that phenomenologically consistent scale-invariant models can be constructed which allow a small positive cosmological constant, providing certain relation between the particle masses is satisfied. As a result, the mass of the dilaton is generated at two-loop level. Another interesting consequence is that the electroweak symmetry-breaking vacuum in such models is necessarily a metastable ''false'' vacuum which, fortunately, is not expected to decay on cosmological time scales.

  20. A Graphical Procedure for the Simultaneous Determination of the Distribution Constant of Iodine and the Stability Constants of Trihalide Anions.

    ERIC Educational Resources Information Center

    Kahwa, I. A.

    1984-01-01

    Discusses a graphical procedure which allows the distribution constant of iodine to be determined simultaneously with the trihalide anion stability constant. In addition, the procedure extends the experimental chemistry from distribution equilibria to important thermodynamic and bonding features. Advantages of using the procedure are also…

  1. Charged structure constants from modularity

    NASA Astrophysics Data System (ADS)

    Das, Diptarka; Datta, Shouvik; Pal, Sridip

    2017-11-01

    We derive a universal formula for the average heavy-heavy-light structure constants for 2 d CFTs with non-vanishing u(1) charge. The derivation utilizes the modular properties of one-point functions on the torus. Refinements in N=2 SCFTs, show that the resulting Cardy-like formula for the structure constants has precisely the same shifts in the central charge as that of the thermodynamic entropy found earlier. This analysis generalizes the recent results by Kraus and Maloney for CFTs with an additional global u(1) symmetry [1]. Our results at large central charge are also shown to match with computations from the holographic dual, which suggest that the averaged CFT three-point coefficient also serves as a useful probe of detecting black hole hair.

  2. Regularizing cosmological singularities by varying physical constants

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

    Dąbrowski, Mariusz P.; Marosek, Konrad, E-mail: mpdabfz@wmf.univ.szczecin.pl, E-mail: k.marosek@wmf.univ.szczecin.pl

    2013-02-01

    Varying physical constant cosmologies were claimed to solve standard cosmological problems such as the horizon, the flatness and the Λ-problem. In this paper, we suggest yet another possible application of these theories: solving the singularity problem. By specifying some examples we show that various cosmological singularities may be regularized provided the physical constants evolve in time in an appropriate way.

  3. The method of constant stimuli is inefficient

    NASA Technical Reports Server (NTRS)

    Watson, Andrew B.; Fitzhugh, Andrew

    1990-01-01

    Simpson (1988) has argued that the method of constant stimuli is as efficient as adaptive methods of threshold estimation and has supported this claim with simulations. It is shown that Simpson's simulations are not a reasonable model of the experimental process and that more plausible simulations confirm that adaptive methods are much more efficient that the method of constant stimuli.

  4. Establishment of feeder-free culture system for human induced pluripotent stem cell on DAS nanocrystalline graphene

    NASA Astrophysics Data System (ADS)

    Lee, Hyunah; Nam, Donggyu; Choi, Jae-Kyung; Araúzo-Bravo, Marcos J.; Kwon, Soon-Yong; Zaehres, Holm; Lee, Taehee; Park, Chan Young; Kang, Hyun-Wook; Schöler, Hans R.; Kim, Jeong Beom

    2016-02-01

    The maintenance of undifferentiated human pluripotent stem cells (hPSC) under xeno-free condition requires the use of human feeder cells or extracellular matrix (ECM) coating. However, human-derived sources may cause human pathogen contamination by viral or non-viral agents to the patients. Here we demonstrate feeder-free and xeno-free culture system for hPSC expansion using diffusion assisted synthesis-grown nanocrystalline graphene (DAS-NG), a synthetic non-biological nanomaterial which completely rule out the concern of human pathogen contamination. DAS-NG exhibited advanced biocompatibilities including surface nanoroughness, oxygen containing functional groups and hydrophilicity. hPSC cultured on DAS-NG could maintain pluripotency in vitro and in vivo, and especially cell adhesion-related gene expression profile was comparable to those of cultured on feeders, while hPSC cultured without DAS-NG differentiated spontaneously with high expression of somatic cell-enriched adhesion genes. This feeder-free and xeno-free culture method using DAS-NG will facilitate the generation of clinical-grade hPSC.

  5. More exact solutions of the constant astigmatism equation

    NASA Astrophysics Data System (ADS)

    Hlaváč, Adam

    2018-01-01

    By using Bäcklund transformation for the sine-Gordon equation, new periodic exact solutions of the constant astigmatism equation zyy +(1 / z) xx + 2 = 0 are generated from a seed which corresponds to Lipschitz surfaces of constant astigmatism.

  6. Scalar-tensor theory of gravitation with negative coupling constant

    NASA Technical Reports Server (NTRS)

    Smalley, L. L.; Eby, P. B.

    1976-01-01

    The possibility of a Brans-Dicke scalar-tensor gravitation theory with a negative coupling constant is considered. The admissibility of a negative-coupling theory is investigated, and a simplified cosmological solution is obtained which allows a negative derivative of the gravitation constant. It is concluded that a Brans-Dicke theory with a negative coupling constant can be a viable alternative to general relativity and that a large negative value for the coupling constant seems to bring the original scalar-tensor theory into close agreement with perihelion-precession results in view of recent observations of small solar oblateness.

  7. Profiles of equilibrium constants for self-association of aromatic molecules

    NASA Astrophysics Data System (ADS)

    Beshnova, Daria A.; Lantushenko, Anastasia O.; Davies, David B.; Evstigneev, Maxim P.

    2009-04-01

    Analysis of the noncovalent, noncooperative self-association of identical aromatic molecules assumes that the equilibrium self-association constants are either independent of the number of molecules (the EK-model) or change progressively with increasing aggregation (the AK-model). The dependence of the self-association constant on the number of molecules in the aggregate (i.e., the profile of the equilibrium constant) was empirically derived in the AK-model but, in order to provide some physical understanding of the profile, it is proposed that the sources for attenuation of the equilibrium constant are the loss of translational and rotational degrees of freedom, the ordering of molecules in the aggregates and the electrostatic contribution (for charged units). Expressions are derived for the profiles of the equilibrium constants for both neutral and charged molecules. Although the EK-model has been widely used in the analysis of experimental data, it is shown in this work that the derived equilibrium constant, KEK, depends on the concentration range used and hence, on the experimental method employed. The relationship has also been demonstrated between the equilibrium constant KEK and the real dimerization constant, KD, which shows that the value of KEK is always lower than KD.

  8. On determining dose rate constants spectroscopically.

    PubMed

    Rodriguez, M; Rogers, D W O

    2013-01-01

    To investigate several aspects of the Chen and Nath spectroscopic method of determining the dose rate constants of (125)I and (103)Pd seeds [Z. Chen and R. Nath, Phys. Med. Biol. 55, 6089-6104 (2010)] including the accuracy of using a line or dual-point source approximation as done in their method, and the accuracy of ignoring the effects of the scattered photons in the spectra. Additionally, the authors investigate the accuracy of the literature's many different spectra for bare, i.e., unencapsulated (125)I and (103)Pd sources. Spectra generated by 14 (125)I and 6 (103)Pd seeds were calculated in vacuo at 10 cm from the source in a 2.7 × 2.7 × 0.05 cm(3) voxel using the EGSnrc BrachyDose Monte Carlo code. Calculated spectra used the initial photon spectra recommended by AAPM's TG-43U1 and NCRP (National Council of Radiation Protection and Measurements) Report 58 for the (125)I seeds, or TG-43U1 and NNDC(2000) (National Nuclear Data Center, 2000) for (103)Pd seeds. The emitted spectra were treated as coming from a line or dual-point source in a Monte Carlo simulation to calculate the dose rate constant. The TG-43U1 definition of the dose rate constant was used. These calculations were performed using the full spectrum including scattered photons or using only the main peaks in the spectrum as done experimentally. Statistical uncertainties on the air kerma/history and the dose rate/history were ≤0.2%. The dose rate constants were also calculated using Monte Carlo simulations of the full seed model. The ratio of the intensity of the 31 keV line relative to that of the main peak in (125)I spectra is, on average, 6.8% higher when calculated with the NCRP Report 58 initial spectrum vs that calculated with TG-43U1 initial spectrum. The (103)Pd spectra exhibit an average 6.2% decrease in the 22.9 keV line relative to the main peak when calculated with the TG-43U1 rather than the NNDC(2000) initial spectrum. The measured values from three different investigations are

  9. Detecting Changes Following the Provision of Assistive Devices: Utility of the WHO-DAS II

    ERIC Educational Resources Information Center

    Raggi, Alberto

    2010-01-01

    The World Health Organization Disability Assessment Schedule II (WHO-DAS II) is a non-disease-specific International Classification of Functioning, Disability, and Health-based disability assessment instrument developed to measure activity limitations and restrictions to participation. The aim of this pilot study is to evaluate WHO-DAS II…

  10. Beauty vector meson decay constants from QCD sum rules

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

    Lucha, Wolfgang; Melikhov, Dmitri; D. V. Skobeltsyn Institute of Nuclear Physics, M. V. Lomonosov Moscow State University, 119991, Moscow

    We present the outcomes of a very recent investigation of the decay constants of nonstrange and strange heavy-light beauty vector mesons, with special emphasis on the ratio of any such decay constant to the decay constant of the corresponding pseudoscalar meson, by means of Borel-transformed QCD sum rules. Our results suggest that both these ratios are below unity.

  11. Optimal trace inequality constants for interior penalty discontinuous Galerkin discretisations of elliptic operators using arbitrary elements with non-constant Jacobians

    NASA Astrophysics Data System (ADS)

    Owens, A. R.; Kópházi, J.; Eaton, M. D.

    2017-12-01

    In this paper, a new method to numerically calculate the trace inequality constants, which arise in the calculation of penalty parameters for interior penalty discretisations of elliptic operators, is presented. These constants are provably optimal for the inequality of interest. As their calculation is based on the solution of a generalised eigenvalue problem involving the volumetric and face stiffness matrices, the method is applicable to any element type for which these matrices can be calculated, including standard finite elements and the non-uniform rational B-splines of isogeometric analysis. In particular, the presented method does not require the Jacobian of the element to be constant, and so can be applied to a much wider variety of element shapes than are currently available in the literature. Numerical results are presented for a variety of finite element and isogeometric cases. When the Jacobian is constant, it is demonstrated that the new method produces lower penalty parameters than existing methods in the literature in all cases, which translates directly into savings in the solution time of the resulting linear system. When the Jacobian is not constant, it is shown that the naive application of existing approaches can result in penalty parameters that do not guarantee coercivity of the bilinear form, and by extension, the stability of the solution. The method of manufactured solutions is applied to a model reaction-diffusion equation with a range of parameters, and it is found that using penalty parameters based on the new trace inequality constants result in better conditioned linear systems, which can be solved approximately 11% faster than those produced by the methods from the literature.

  12. Optical constants of concentrated aqueous ammonium sulfate.

    NASA Technical Reports Server (NTRS)

    Remsberg, E. E.

    1973-01-01

    Using experimental data obtained from applying spectroscopy to a 39-wt-% aqueous ammonium sulfate solution, it is shown that, even though specific aerosol optical constants appear quite accurate, spectral variations may exist as functions of material composition or concentration or both. Prudent users of optical constant data must then include liberal data error estimates when performing calculations or in interpreting spectroscopic surveys of collected aerosol material.

  13. Elastic constants from microscopic strain fluctuations

    PubMed

    Sengupta; Nielaba; Rao; Binder

    2000-02-01

    Fluctuations of the instantaneous local Lagrangian strain epsilon(ij)(r,t), measured with respect to a static "reference" lattice, are used to obtain accurate estimates of the elastic constants of model solids from atomistic computer simulations. The measured strains are systematically coarse-grained by averaging them within subsystems (of size L(b)) of a system (of total size L) in the canonical ensemble. Using a simple finite size scaling theory we predict the behavior of the fluctuations as a function of L(b)/L and extract elastic constants of the system in the thermodynamic limit at nonzero temperature. Our method is simple to implement, efficient, and general enough to be able to handle a wide class of model systems, including those with singular potentials without any essential modification. We illustrate the technique by computing isothermal elastic constants of "hard" and "soft" disk triangular solids in two dimensions from Monte Carlo and molecular dynamics simulations. We compare our results with those from earlier simulations and theory.

  14. Numerical study of anomalous dynamic scaling behaviour of (1+1)-dimensional Das Sarma-Tamborenea model

    NASA Astrophysics Data System (ADS)

    Xun, Zhi-Peng; Tang, Gang; Han, Kui; Hao, Da-Peng; Xia, Hui; Zhou, Wei; Yang, Xi-Quan; Wen, Rong-Ji; Chen, Yu-Ling

    2010-07-01

    In order to discuss the finite-size effect and the anomalous dynamic scaling behaviour of Das Sarma-Tamborenea growth model, the (1+1)-dimensional Das Sarma-Tamborenea model is simulated on a large length scale by using the kinetic Monte-Carlo method. In the simulation, noise reduction technique is used in order to eliminate the crossover effect. Our results show that due to the existence of the finite-size effect, the effective global roughness exponent of the (1+1)-dimensional Das Sarma-Tamborenea model systematically decreases with system size L increasing when L > 256. This finding proves the conjecture by Aarao Reis[Aarao Reis F D A 2004 Phys. Rev. E 70 031607]. In addition, our simulation results also show that the Das Sarma-Tamborenea model in 1+1 dimensions indeed exhibits intrinsic anomalous scaling behaviour.

  15. Direct Measurement of Equilibrium Constants for High-Affinity Hemoglobins

    PubMed Central

    Kundu, Suman; Premer, Scott A.; Hoy, Julie A.; Trent, James T.; Hargrove, Mark S.

    2003-01-01

    The biological functions of heme proteins are linked to their rate and affinity constants for ligand binding. Kinetic experiments are commonly used to measure equilibrium constants for traditional hemoglobins comprised of pentacoordinate ligand binding sites and simple bimolecular reaction schemes. However, kinetic methods do not always yield reliable equilibrium constants with more complex hemoglobins for which reaction mechanisms are not clearly understood. Furthermore, even where reaction mechanisms are clearly understood, it is very difficult to directly measure equilibrium constants for oxygen and carbon monoxide binding to high-affinity (KD ≪ 1 μM) hemoglobins. This work presents a method for direct measurement of equilibrium constants for high-affinity hemoglobins that utilizes a competition for ligands between the "target" protein and an array of "scavenger" hemoglobins with known affinities. This method is described for oxygen and carbon monoxide binding to two hexacoordinate hemoglobins: rice nonsymbiotic hemoglobin and Synechocystis hemoglobin. Our results demonstrate that although these proteins have different mechanisms for ligand binding, their affinities for oxygen and carbon monoxide are similar. Their large affinity constants for oxygen, 285 and ∼100 μM−1 respectively, indicate that they are not capable of facilitating oxygen transport. PMID:12770899

  16. Size-dependent Hamaker constants for silver and gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Pinchuk, Pavlo; Jiang, Ke

    2015-08-01

    Hamaker-Lifshitz constants are material specific constants that are used to calculate van der Waals interaction forces between small particles in solution. Typically, these constants are size-independent and material specific. According to the Lifshitz theory, the Hamaker-Lifshitz constants can be calculated by taking integrals that include the dielectric permittivity, as a function of frequency, of the interacting particles and the medium around particles. The dielectric permittivity of interacting metal nanoparticles can be calculated using the Drude model, which is based on the assumption of motion of free conducting electrons. For bulk metals, the Drude model does not predict any sizedependence of the dielectric permittivity. However, the conducting electrons in small noble metal nanoparticles (R ~ 10nm) exhibit surface scattering, which changes the complex permittivity function. In this work, we show theoretically that scattering of the free conducting electrons inside silver and gold nanoparticles with the size of 1 - 50 nm leads to size-dependent dielectric permittivity and Hamaker-Lifshitz constants. We calculate numerically the Hamaker-Lifshitz constants for silver and gold nanoparticles with different diameters. The results of the study might be of interests for understanding colloidal stability of metal nanoparticles.

  17. Non-minimally coupled varying constants quantum cosmologies

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

    Balcerzak, Adam, E-mail: abalcerz@wmf.univ.szczecin.pl

    We consider gravity theory with varying speed of light and varying gravitational constant. Both constants are represented by non-minimally coupled scalar fields. We examine the cosmological evolution in the near curvature singularity regime. We find that at the curvature singularity the speed of light goes to infinity while the gravitational constant vanishes. This corresponds to the Newton's Mechanics limit represented by one of the vertex of the Bronshtein-Zelmanov-Okun cube [1,2]. The cosmological evolution includes both the pre-big-bang and post-big-bang phases separated by the curvature singularity. We also investigate the quantum counterpart of the considered theory and find the probability ofmore » transition of the universe from the collapsing pre-big-bang phase to the expanding post-big-bang phase.« less

  18. Negative Dielectric Constant Material Based on Ion Conducting Materials

    NASA Technical Reports Server (NTRS)

    Gordon, Keith L. (Inventor); Kang, Jin Ho (Inventor); Park, Cheol (Inventor); Lillehei, Peter T. (Inventor); Harrison, Joycelyn S. (Inventor)

    2017-01-01

    Metamaterials or artificial negative index materials (NIMs) have generated great attention due to their unique and exotic electromagnetic properties. One exemplary negative dielectric constant material, which is an essential key for creating the NIMs, was developed by doping ions into a polymer, a protonated poly (benzimidazole) (PBI). The doped PBI showed a negative dielectric constant at megahertz (MHz) frequencies due to its reduced plasma frequency and an induction effect. The magnitude of the negative dielectric constant and the resonance frequency were tunable by doping concentration. The highly doped PBI showed larger absolute magnitude of negative dielectric constant at just above its resonance frequency than the less doped PBI.

  19. Negative Dielectric Constant Material Based on Ion Conducting Materials

    NASA Technical Reports Server (NTRS)

    Gordon, Keith L. (Inventor); Kang, Jin Ho (Inventor); Harrison, Joycelyn S. (Inventor); Park, Cheol (Inventor); Lillehei, Peter T. (Inventor)

    2014-01-01

    Metamaterials or artificial negative index materials (NIMs) have generated great attention due to their unique and exotic electromagnetic properties. One exemplary negative dielectric constant material, which is an essential key for creating the NIMs, was developed by doping ions into a polymer, a protonated poly(benzimidazole) (PBI). The doped PBI showed a negative dielectric constant at megahertz (MHz) frequencies due to its reduced plasma frequency and an induction effect. The magnitude of the negative dielectric constant and the resonance frequency were tunable by doping concentration. The highly doped PBI showed larger absolute magnitude of negative dielectric constant at just above its resonance frequency than the less doped PBI.

  20. A simple cosmology with a varying fine structure constant.

    PubMed

    Sandvik, Håvard Bunes; Barrow, John D; Magueijo, João

    2002-01-21

    We investigate the cosmological consequences of a theory in which the electric charge e can vary. In this theory the fine structure "constant," alpha, remains almost constant in the radiation era, undergoes a small increase in the matter era, but approaches a constant value when the universe starts accelerating because of a positive cosmological constant. This model satisfies geonuclear, nucleosynthesis, and cosmic microwave background constraints on time variation in alpha, while fitting the observed accelerating Universe and evidence for small alpha variations in quasar spectra. It also places specific restrictions on the nature of the dark matter. Further tests, involving stellar spectra and Eötvös experiments, are proposed.

  1. Determination of the Boltzmann constant by dielectric-constant gas thermometry

    NASA Astrophysics Data System (ADS)

    Fellmuth, Bernd; Fischer, Joachim; Gaiser, Christof; Jusko, Otto; Priruenrom, Tasanee; Sabuga, Wladimir; Zandt, Thorsten

    2011-10-01

    Within an international project directed to the new definition of the base unit kelvin, the Boltzmann constant k has been determined by dielectric-constant gas thermometry at PTB. In the pressure range from about 1 MPa to 7 MPa, 11 helium isotherms have been measured at the triple point of water (TPW) by applying a new special experimental setup consisting of a large-volume thermostat, a vacuum-isolated measuring system, stainless-steel 10 pF cylindrical capacitors, an autotransformer ratio capacitance bridge, a high-purity gas-handling system including a mass spectrometer, and traceably calibrated special pressure balances with piston-cylinder assemblies having effective areas of 2 cm2. The value of k has been deduced from the linear, ideal-gas term of an appropriate virial expansion fitted to the combined isotherms. A detailed uncertainty budget has been established by performing Monte Carlo simulations. The main uncertainty components result from the measurement of pressure and capacitance as well as the influence of the effective compressibility of the measuring capacitor and impurities contained in the helium gas. The combination of the results obtained at the TPW (kTPW = 1.380 654 × 10-23 J K-1, relative standard uncertainty 9.2 parts per million) with data measured earlier at low temperatures (21 K to 27 K, kLT = 1.380 657 × 10-23 J K-1, 15.9 parts per million) has yielded a value of k = 1.380 655 × 10-23 J K-1 with uncertainty of 7.9 parts per million.

  2. Chandra Independently Determines Hubble Constant

    NASA Astrophysics Data System (ADS)

    2006-08-01

    A critically important number that specifies the expansion rate of the Universe, the so-called Hubble constant, has been independently determined using NASA's Chandra X-ray Observatory. This new value matches recent measurements using other methods and extends their validity to greater distances, thus allowing astronomers to probe earlier epochs in the evolution of the Universe. "The reason this result is so significant is that we need the Hubble constant to tell us the size of the Universe, its age, and how much matter it contains," said Max Bonamente from the University of Alabama in Huntsville and NASA's Marshall Space Flight Center (MSFC) in Huntsville, Ala., lead author on the paper describing the results. "Astronomers absolutely need to trust this number because we use it for countless calculations." Illustration of Sunyaev-Zeldovich Effect Illustration of Sunyaev-Zeldovich Effect The Hubble constant is calculated by measuring the speed at which objects are moving away from us and dividing by their distance. Most of the previous attempts to determine the Hubble constant have involved using a multi-step, or distance ladder, approach in which the distance to nearby galaxies is used as the basis for determining greater distances. The most common approach has been to use a well-studied type of pulsating star known as a Cepheid variable, in conjunction with more distant supernovae to trace distances across the Universe. Scientists using this method and observations from the Hubble Space Telescope were able to measure the Hubble constant to within 10%. However, only independent checks would give them the confidence they desired, considering that much of our understanding of the Universe hangs in the balance. Chandra X-ray Image of MACS J1149.5+223 Chandra X-ray Image of MACS J1149.5+223 By combining X-ray data from Chandra with radio observations of galaxy clusters, the team determined the distances to 38 galaxy clusters ranging from 1.4 billion to 9.3 billion

  3. On the Kolmogorov constant in stochastic turbulence models

    NASA Astrophysics Data System (ADS)

    Heinz, Stefan

    2002-11-01

    The Kolmogorov constant is fundamental in stochastic models of turbulence. To explain the reasons for observed variations of this quantity, it is calculated for two flows by various methods and data. Velocity fluctuations are considered as the sum of contributions due to anisotropy, acceleration fluctuations and stochastic forcing that is controlled by the Kolmogorov constant. It is shown that the effects of anisotropy and acceleration fluctuations are responsible for significant variations of the Kolmogorov constant. It is found near 2 for flows where anisotropy and acceleration fluctuations contribute to the energy budget, and near 6 if such contributions disappear.

  4. Procedures for determining MATMOD-4V material constants

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

    Lowe, T.C.

    1993-11-01

    The MATMOD-4V constitutive relations were developed from the original MATMOD model to extend the range of nonelastic deformation behaviors represented to include transient phenomena such as strain softening. Improvements in MATMOD-4V increased the number of independent material constants and the difficulty in determining their values. Though the constitutive relations are conceptually simple, their form and procedures for obtaining their constants can be complex. This paper reviews in detail the experiments, numerical procedures, and assumptions that have been used to determine a complete set of MATMOD-4V constants for high purity aluminum.

  5. Earthquake recording at the Stanford DAS Array with fibers in existing telecomm conduits

    NASA Astrophysics Data System (ADS)

    Biondi, B. C.; Martin, E. R.; Yuan, S.; Cole, S.; Karrenbach, M. H.

    2017-12-01

    The Stanford Distributed Acoustic Sensing Array (SDASA-1) has been continuously recording seismic data since September 2016 on 2.5 km of single mode fiber optics in existing telecommunications conduits under Stanford's campus. The array is figure-eight shaped and roughly 600 m along its widest side with a channel spacing of roughly 8 m. This array is easy to maintain and is nonintrusive, making it well suited to urban environments, but it sacrifices some cable-to-ground coupling compared to more traditional seismometers. We have been testing its utility for earthquake recording, active seismic, and ambient noise interferometry. This talk will focus on earthquake observations. We will show comparisons between the strain rates measured throughout the DAS array and the particle velocities measured at the nearby Jasper Ridge Seismic Station (JRSC). In some of these events, we will point out directionality features specific to DAS that can require slight modifications in data processing. We also compare repeatability of DAS and JRSC recordings of blasts from a nearby quarry. Using existing earthquake databases, we have created a small catalog of DAS earthquake observations by pulling records of over 700 Northern California events spanning Sep. 2016 to Jul. 2017 from both the DAS data and JRSC. On these events we have tested common array methods for earthquake detection and location including beamforming and STA/LTA analysis in time and frequency. We have analyzed these events to approximate thresholds on what distances and magnitudes are clearly detectible by the DAS array. Further analysis should be done on detectability with methods tailored to small events (for example, template matching). In creating this catalog, we have developed open source software available for free download that can manage large sets of continuous seismic data files (both existing files, and files as they stream in). This software can both interface with existing earthquake networks, and

  6. Methodology for extracting local constants from petroleum cracking flows

    DOEpatents

    Chang, Shen-Lin; Lottes, Steven A.; Zhou, Chenn Q.

    2000-01-01

    A methodology provides for the extraction of local chemical kinetic model constants for use in a reacting flow computational fluid dynamics (CFD) computer code with chemical kinetic computations to optimize the operating conditions or design of the system, including retrofit design improvements to existing systems. The coupled CFD and kinetic computer code are used in combination with data obtained from a matrix of experimental tests to extract the kinetic constants. Local fluid dynamic effects are implicitly included in the extracted local kinetic constants for each particular application system to which the methodology is applied. The extracted local kinetic model constants work well over a fairly broad range of operating conditions for specific and complex reaction sets in specific and complex reactor systems. While disclosed in terms of use in a Fluid Catalytic Cracking (FCC) riser, the inventive methodology has application in virtually any reaction set to extract constants for any particular application and reaction set formulation. The methodology includes the step of: (1) selecting the test data sets for various conditions; (2) establishing the general trend of the parametric effect on the measured product yields; (3) calculating product yields for the selected test conditions using coupled computational fluid dynamics and chemical kinetics; (4) adjusting the local kinetic constants to match calculated product yields with experimental data; and (5) validating the determined set of local kinetic constants by comparing the calculated results with experimental data from additional test runs at different operating conditions.

  7. Psychometric Properties of the Disability Assessment Schedule (DAS) for Behavior Problems: An Independent Investigation

    ERIC Educational Resources Information Center

    Tsakanikos, Elias; Underwood, Lisa; Sturmey, Peter; Bouras, Nick; McCarthy, Jane

    2011-01-01

    The present study employed the Disability Assessment Schedule (DAS) to assess problem behaviors in a large sample of adults with ID (N = 568) and evaluate the psychometric properties of this instrument. Although the DAS problem behaviors were found to be internally consistent (Cronbach's [alpha] = 0.87), item analysis revealed one weak item…

  8. Scene-based nonuniformity correction using local constant statistics.

    PubMed

    Zhang, Chao; Zhao, Wenyi

    2008-06-01

    In scene-based nonuniformity correction, the statistical approach assumes all possible values of the true-scene pixel are seen at each pixel location. This global-constant-statistics assumption does not distinguish fixed pattern noise from spatial variations in the average image. This often causes the "ghosting" artifacts in the corrected images since the existing spatial variations are treated as noises. We introduce a new statistical method to reduce the ghosting artifacts. Our method proposes a local-constant statistics that assumes that the temporal signal distribution is not constant at each pixel but is locally true. This considers statistically a constant distribution in a local region around each pixel but uneven distribution in a larger scale. Under the assumption that the fixed pattern noise concentrates in a higher spatial-frequency domain than the distribution variation, we apply a wavelet method to the gain and offset image of the noise and separate out the pattern noise from the spatial variations in the temporal distribution of the scene. We compare the results to the global-constant-statistics method using a clean sequence with large artificial pattern noises. We also apply the method to a challenging CCD video sequence and a LWIR sequence to show how effective it is in reducing noise and the ghosting artifacts.

  9. Anbindung des SISIS-SunRise-Bibliothekssystems an das zentrale Identitätsmanagement

    NASA Astrophysics Data System (ADS)

    Ebner, Ralf; Pretz, Edwin

    Wir berichten über Konzepte und Implementierungen zur Datenprovisionierung aus den Personenverwaltungssystemen der Technischen Universität München (TUM) über das zentrale Metadirectory am Leibniz-Rechenzentrum (LRZ) in das SISIS-SunRise-Bibliothekssystem der Universitätsbibliothek der TUM (TUB). Es werden drei Implementierungsvarianten diskutiert, angefangen von der Generierung und Übertragung einfacher CSV-Dateien über ein OpenLDAP-basiertes Konzept als Backend für die SISIS-Datenbank bis zur endgültigen Implementierung mit dem OCLC IDM Connector.

  10. Projection rule for complex-valued associative memory with large constant terms

    NASA Astrophysics Data System (ADS)

    Kitahara, Michimasa; Kobayashi, Masaki

    Complex-valued Associative Memory (CAM) has an inherent property of rotation invariance. Rotation invariance produces many undesirable stable states and reduces the noise robustness of CAM. Constant terms may remove rotation invariance, but if the constant terms are too small, rotation invariance does not vanish. In this paper, we eliminate rotation invariance by introducing large constant terms to complex-valued neurons. We have to make constant terms sufficiently large to improve the noise robustness. We introduce a parameter to control the amplitudes of constant terms into projection rule. The large constant terms are proved to be effective by our computer simulations.

  11. Role of dielectric constant in electrohydrodynamics of conducting fluids

    NASA Technical Reports Server (NTRS)

    Rhodes, Percy H.; Snyder, Robert S.; Roberts, Glyn O.

    1992-01-01

    Electrohydrodynamic (EHD) flows are driven by the interaction of an electric field with variations in electric conductivity or dielectric constant. In reported EHD experiments on the deformation of drops of immiscible dielectric fluids, the role of conductivity has tended to overshadow the role of dielectric constant. Often, large conductivity contrasts were convenient because the conductivities of the dielectric fluid were relatively uncertain. As a result, the observed effects were always qualitatively the same as if there had been no contrast in dielectric constant. Our early experiments studying the EHC deformations of cylindrical streams readily showed the conductivity effect but the dielectric constant effect was not discernible. We have modified our flow chamber and improved our method of observation and can now see an unequivocal dielectric constant effect which is in agreement with the prior theory. In this paper we first give a brief description of the physics of charge buildup at the interface of an immersed spherical drop or flowing cylindrical sample stream and then show how these charge distributions lead to interface distortions and accompanying viscous flows which constitute EHD. We next review theory and experiment describing the deformation of spherical drops. We show that in the reported drop deformation experiments, the contrast in dielectric constant was never sufficient to reverse the deformation due to the conductivity contrast. We review our work describing the deformation of a cylindrical stream of one fluid flowing in a parallel flow of another, and we compare the deformation equations with those for spherical drops. Finally, we show a definite experimental dielectric constant effect for cylindrical stream of aqueous polystyrene latex suspension. The dielectric constant varies with the frequency of the imposed electric field, and the associated EHD flow change is very apparent.

  12. Getting through to circadian oscillators: why use constant routines?

    NASA Technical Reports Server (NTRS)

    Duffy, Jeanne F.; Dijk, Derk-Jan

    2002-01-01

    Overt 24-h rhythmicity is composed of both exogenous and endogenous components, reflecting the product of multiple (periodic) feedback loops with a core pacemaker at their center. Researchers attempting to reveal the endogenous circadian (near 24-h) component of rhythms commonly conduct their experiments under constant environmental conditions. However, even under constant environmental conditions, rhythmic changes in behavior, such as food intake or the sleep-wake cycle, can contribute to observed rhythmicity in many physiological and endocrine variables. Assessment of characteristics of the core circadian pacemaker and its direct contribution to rhythmicity in different variables, including rhythmicity in gene expression, may be more reliable when such periodic behaviors are eliminated or kept constant across all circadian phases. This is relevant for the assessment of the status of the circadian pacemaker in situations in which the sleep-wake cycle or food intake regimes are altered because of external conditions, such as in shift work or jet lag. It is also relevant for situations in which differences in overt rhythmicity could be due to changes in either sleep oscillatory processes or circadian rhythmicity, such as advanced or delayed sleep phase syndromes, in aging, or in particular clinical conditions. Researchers studying human circadian rhythms have developed constant routine protocols to assess the status of the circadian pacemaker in constant behavioral and environmental conditions, whereas this technique is often thought to be unnecessary in the study of animal rhythms. In this short review, the authors summarize constant routine methodology and what has been learned from constant routines and argue that animal and human circadian rhythm researchers should (continue to) use constant routines as a step on the road to getting through to central and peripheral circadian oscillators in the intact organism.

  13. Variación temporal de las constantes fundamentales

    NASA Astrophysics Data System (ADS)

    Landau, S. J.; Vucetich, H.

    La variación temporal de las constantes fundamentales es un problema que ha motivado numerosos trabajos teóricos y experimentales desde la hipótesis de los grandes números de Dirac en 1937. Entre los métodos experimentales y observacionales para establecer restricciones sobre la variación de las constantes fundamentes es importante mencionar: comparación entre relojes atómicos[1], métodos geofísicos[2][3], análisis de sistemas de absorción en quasares[4][5][6] y cotas provenientes de la nucleosíntesis primordial[7]. En un trabajo reciente[5], se reportó una significativa variación en la constante de estructura fina. Intentos de unificar las cuatro interacciones fundamentales dieron como resultado teorías con múltiples dimensiones como las teorías de Kaluza-Klein y teorías de supercuerdas. Estas teorías proporcionan un marco teórico natural para el estudio de la variación temporal de las constantes fundamentales. A su vez, un modelo sencillo para estudiar la variación de la constante de estructura fina, fue propuesto en [8], a partir de premisas muy generales como ser covarianza, invarianza de gauge, causalidad y invarianza ante reversiones temporales en el electromagnetismo. Diferentes versiones de las teorías antes mencionadas coinciden en predecir variaciones temporales de las constantes fundamentales pero difieren en la forma de esta variación[9][10]. De esta manera, las restricciones establecidas experimentalmente sobre la variación de las constantes fundamentales pueden ser una herramienta importante para testear estas diferentes teorías. En este trabajo, utilizamos las cotas provenientes de diversas técnicas experimentales, para testear si las mismas son consistentes con alguna de las teorías antes mencionadas. En particular, establecemos cotas sobre la variación de los parámentros libres de las diferentes teorías como por ejemplo el radio de las dimensiones extras en las teorías tipo Kaluza-Klein.

  14. Fast optimization algorithms and the cosmological constant

    NASA Astrophysics Data System (ADS)

    Bao, Ning; Bousso, Raphael; Jordan, Stephen; Lackey, Brad

    2017-11-01

    Denef and Douglas have observed that in certain landscape models the problem of finding small values of the cosmological constant is a large instance of a problem that is hard for the complexity class NP (Nondeterministic Polynomial-time). The number of elementary operations (quantum gates) needed to solve this problem by brute force search exceeds the estimated computational capacity of the observable Universe. Here we describe a way out of this puzzling circumstance: despite being NP-hard, the problem of finding a small cosmological constant can be attacked by more sophisticated algorithms whose performance vastly exceeds brute force search. In fact, in some parameter regimes the average-case complexity is polynomial. We demonstrate this by explicitly finding a cosmological constant of order 10-120 in a randomly generated 1 09-dimensional Arkani-Hamed-Dimopoulos-Kachru landscape.

  15. Convexity and concavity constants in Lorentz and Marcinkiewicz spaces

    NASA Astrophysics Data System (ADS)

    Kaminska, Anna; Parrish, Anca M.

    2008-07-01

    We provide here the formulas for the q-convexity and q-concavity constants for function and sequence Lorentz spaces associated to either decreasing or increasing weights. It yields also the formula for the q-convexity constants in function and sequence Marcinkiewicz spaces. In this paper we extent and enhance the results from [G.J.O. Jameson, The q-concavity constants of Lorentz sequence spaces and related inequalities, Math. Z. 227 (1998) 129-142] and [A. Kaminska, A.M. Parrish, The q-concavity and q-convexity constants in Lorentz spaces, in: Banach Spaces and Their Applications in Analysis, Conference in Honor of Nigel Kalton, May 2006, Walter de Gruyter, Berlin, 2007, pp. 357-373].

  16. The constant displacement scheme for tracking particles in heterogeneous aquifers

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

    Wen, X.H.; Gomez-Hernandez, J.J.

    1996-01-01

    Simulation of mass transport by particle tracking or random walk in highly heterogeneous media may be inefficient from a computational point of view if the traditional constant time step scheme is used. A new scheme which adjusts automatically the time step for each particle according to the local pore velocity, so that each particle always travels a constant distance, is shown to be computationally faster for the same degree of accuracy than the constant time step method. Using the constant displacement scheme, transport calculations in a 2-D aquifer model, with nature log-transmissivity variance of 4, can be 8.6 times fastermore » than using the constant time step scheme.« less

  17. Constant-current control method of multi-function electromagnetic transmitter.

    PubMed

    Xue, Kaichang; Zhou, Fengdao; Wang, Shuang; Lin, Jun

    2015-02-01

    Based on the requirements of controlled source audio-frequency magnetotelluric, DC resistivity, and induced polarization, a constant-current control method is proposed. Using the required current waveforms in prospecting as a standard, the causes of current waveform distortion and current waveform distortion's effects on prospecting are analyzed. A cascaded topology is adopted to achieve 40 kW constant-current transmitter. The responsive speed and precision are analyzed. According to the power circuit of the transmitting system, the circuit structure of the pulse width modulation (PWM) constant-current controller is designed. After establishing the power circuit model of the transmitting system and the PWM constant-current controller model, analyzing the influence of ripple current, and designing an open-loop transfer function according to the amplitude-frequency characteristic curves, the parameters of the PWM constant-current controller are determined. The open-loop transfer function indicates that the loop gain is no less than 28 dB below 160 Hz, which assures the responsive speed of the transmitting system; the phase margin is 45°, which assures the stabilization of the transmitting system. Experimental results verify that the proposed constant-current control method can keep the control error below 4% and can effectively suppress load change caused by the capacitance of earth load.

  18. Constant-current control method of multi-function electromagnetic transmitter

    NASA Astrophysics Data System (ADS)

    Xue, Kaichang; Zhou, Fengdao; Wang, Shuang; Lin, Jun

    2015-02-01

    Based on the requirements of controlled source audio-frequency magnetotelluric, DC resistivity, and induced polarization, a constant-current control method is proposed. Using the required current waveforms in prospecting as a standard, the causes of current waveform distortion and current waveform distortion's effects on prospecting are analyzed. A cascaded topology is adopted to achieve 40 kW constant-current transmitter. The responsive speed and precision are analyzed. According to the power circuit of the transmitting system, the circuit structure of the pulse width modulation (PWM) constant-current controller is designed. After establishing the power circuit model of the transmitting system and the PWM constant-current controller model, analyzing the influence of ripple current, and designing an open-loop transfer function according to the amplitude-frequency characteristic curves, the parameters of the PWM constant-current controller are determined. The open-loop transfer function indicates that the loop gain is no less than 28 dB below 160 Hz, which assures the responsive speed of the transmitting system; the phase margin is 45°, which assures the stabilization of the transmitting system. Experimental results verify that the proposed constant-current control method can keep the control error below 4% and can effectively suppress load change caused by the capacitance of earth load.

  19. Annotation and visualization of endogenous retroviral sequences using the Distributed Annotation System (DAS) and eBioX

    PubMed Central

    Martínez Barrio, Álvaro; Lagercrantz, Erik; Sperber, Göran O; Blomberg, Jonas; Bongcam-Rudloff, Erik

    2009-01-01

    Background The Distributed Annotation System (DAS) is a widely used network protocol for sharing biological information. The distributed aspects of the protocol enable the use of various reference and annotation servers for connecting biological sequence data to pertinent annotations in order to depict an integrated view of the data for the final user. Results An annotation server has been devised to provide information about the endogenous retroviruses detected and annotated by a specialized in silico tool called RetroTector. We describe the procedure to implement the DAS 1.5 protocol commands necessary for constructing the DAS annotation server. We use our server to exemplify those steps. Data distribution is kept separated from visualization which is carried out by eBioX, an easy to use open source program incorporating multiple bioinformatics utilities. Some well characterized endogenous retroviruses are shown in two different DAS clients. A rapid analysis of areas free from retroviral insertions could be facilitated by our annotations. Conclusion The DAS protocol has shown to be advantageous in the distribution of endogenous retrovirus data. The distributed nature of the protocol is also found to aid in combining annotation and visualization along a genome in order to enhance the understanding of ERV contribution to its evolution. Reference and annotation servers are conjointly used by eBioX to provide visualization of ERV annotations as well as other data sources. Our DAS data source can be found in the central public DAS service repository, , or at . PMID:19534743

  20. Microfabricated microengine with constant rotation rate

    DOEpatents

    Romero, Louis A.; Dickey, Fred M.

    1999-01-01

    A microengine uses two synchronized linear actuators as a power source and converts oscillatory motion from the actuators into constant rotational motion via direct linkage connection to an output gear or wheel. The microengine provides output in the form of a continuously rotating output gear that is capable of delivering drive torque at a constant rotation to a micromechanism. The output gear can have gear teeth on its outer perimeter for directly contacting a micromechanism requiring mechanical power. The gear is retained by a retaining means which allows said gear to rotate freely. The microengine is microfabricated of polysilicon on one wafer using surface micromachining batch fabrication.

  1. Cosmological constant implementing Mach principle in general relativity

    NASA Astrophysics Data System (ADS)

    Namavarian, Nadereh; Farhoudi, Mehrdad

    2016-10-01

    We consider the fact that noticing on the operational meaning of the physical concepts played an impetus role in the appearance of general relativity (GR). Thus, we have paid more attention to the operational definition of the gravitational coupling constant in this theory as a dimensional constant which is gained through an experiment. However, as all available experiments just provide the value of this constant locally, this coupling constant can operationally be meaningful only in a local area. Regarding this point, to obtain an extension of GR for the large scale, we replace it by a conformal invariant model and then, reduce this model to a theory for the cosmological scale via breaking down the conformal symmetry through singling out a specific conformal frame which is characterized by the large scale characteristics of the universe. Finally, we come to the same field equations that historically were proposed by Einstein for the cosmological scale (GR plus the cosmological constant) as the result of his endeavor for making GR consistent with the Mach principle. However, we declare that the obtained field equations in this alternative approach do not carry the problem of the field equations proposed by Einstein for being consistent with Mach's principle (i.e., the existence of de Sitter solution), and can also be considered compatible with this principle in the Sciama view.

  2. Semiconductor photoelastic constants measured by light scattering in superlattices

    NASA Astrophysics Data System (ADS)

    He, J.; Sapriel, J.; Brugger, H.

    1989-03-01

    The technique for the measurement of the photoelastic constants that is based on light scattering (Raman and Brillouin) by superlattice acoustic phonons is refined and applied to Ga1-xAlxAs and Si1-xGex materials. The photoelastic constants of Ga1-xAlxAs with respect to GaAs and those of Si0.5Ge0.5 with respect to Si are measured as a function of the wavelength of the laser excitation. One finds that the photoelastic constant of Ga1-xAlxAs undergoes a nonlinear variation with the aluminum concentration x and that the ratio of the photoelastic constants of Si0.5Ge0.5 and Si varies strongly as a function of laser wavelength.

  3. Anharmonic Potential Constants and Their Dependence Upon Bond Length

    DOE R&D Accomplishments Database

    Herschbach, D. R.; Laurie, V. W.

    1961-01-01

    Empirical study of cubic and quartic vibrational force constants for diatomic molecules shows them to be approximately exponential functions of internuclear distance. A family of curves is obtained, determined by the location of the bonded atoms in rows of the periodic table. Displacements between successive curves correspond closely to those in Badger's rule for quadratic force constants (for which the parameters are redetermined to accord with all data now available). Constants for excited electronic and ionic states appear on practically the same curves as those for the ground states. Predictions based on the diatomic correlations agree with the available cubic constants for bond stretching in polyatomic molecules, regardless of the type of bonding involved. Implications of these regularities are discussed. (auth)

  4. A model for solar constant secular changes

    NASA Technical Reports Server (NTRS)

    Schatten, Kenneth H.

    1988-01-01

    In this paper, contrast models for solar active region and global photospheric features are used to reproduce the observed Active Cavity Radiometer and Earth Radiation Budget secular trends in reasonably good fashion. A prediction for the next decade of solar constant variations is made using the model. Secular trends in the solar constant obtained from the present model support the view that the Maunder Minimum may be related to the Little Ice Age of the 17th century.

  5. On determining dose rate constants spectroscopically

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

    Rodriguez, M.; Rogers, D. W. O.

    2013-01-15

    Purpose: To investigate several aspects of the Chen and Nath spectroscopic method of determining the dose rate constants of {sup 125}I and {sup 103}Pd seeds [Z. Chen and R. Nath, Phys. Med. Biol. 55, 6089-6104 (2010)] including the accuracy of using a line or dual-point source approximation as done in their method, and the accuracy of ignoring the effects of the scattered photons in the spectra. Additionally, the authors investigate the accuracy of the literature's many different spectra for bare, i.e., unencapsulated {sup 125}I and {sup 103}Pd sources. Methods: Spectra generated by 14 {sup 125}I and 6 {sup 103}Pd seedsmore » were calculated in vacuo at 10 cm from the source in a 2.7 Multiplication-Sign 2.7 Multiplication-Sign 0.05 cm{sup 3} voxel using the EGSnrc BrachyDose Monte Carlo code. Calculated spectra used the initial photon spectra recommended by AAPM's TG-43U1 and NCRP (National Council of Radiation Protection and Measurements) Report 58 for the {sup 125}I seeds, or TG-43U1 and NNDC(2000) (National Nuclear Data Center, 2000) for {sup 103}Pd seeds. The emitted spectra were treated as coming from a line or dual-point source in a Monte Carlo simulation to calculate the dose rate constant. The TG-43U1 definition of the dose rate constant was used. These calculations were performed using the full spectrum including scattered photons or using only the main peaks in the spectrum as done experimentally. Statistical uncertainties on the air kerma/history and the dose rate/history were Less-Than-Or-Slanted-Equal-To 0.2%. The dose rate constants were also calculated using Monte Carlo simulations of the full seed model. Results: The ratio of the intensity of the 31 keV line relative to that of the main peak in {sup 125}I spectra is, on average, 6.8% higher when calculated with the NCRP Report 58 initial spectrum vs that calculated with TG-43U1 initial spectrum. The {sup 103}Pd spectra exhibit an average 6.2% decrease in the 22.9 keV line relative to the main peak

  6. The contrasting roles of Planck's constant in classical and quantum theories

    NASA Astrophysics Data System (ADS)

    Boyer, Timothy H.

    2018-04-01

    We trace the historical appearance of Planck's constant in physics, and we note that initially the constant did not appear in connection with quanta. Furthermore, we emphasize that Planck's constant can appear in both classical and quantum theories. In both theories, Planck's constant sets the scale of atomic phenomena. However, the roles played in the foundations of the theories are sharply different. In quantum theory, Planck's constant is crucial to the structure of the theory. On the other hand, in classical electrodynamics, Planck's constant is optional, since it appears only as the scale factor for the (homogeneous) source-free contribution to the general solution of Maxwell's equations. Since classical electrodynamics can be solved while taking the homogenous source-free contribution in the solution as zero or non-zero, there are naturally two different theories of classical electrodynamics, one in which Planck's constant is taken as zero and one where it is taken as non-zero. The textbooks of classical electromagnetism present only the version in which Planck's constant is taken to vanish.

  7. Cohesive Energy-Lattice Constant and Bulk Modulus-Lattice Constant Relationships: Alkali Halides, Ag Halides, Tl Halides

    NASA Technical Reports Server (NTRS)

    Schlosser, Herbert

    1992-01-01

    In this note we present two expressions relating the cohesive energy, E(sub coh), and the zero pressure isothermal bulk modulus, B(sub 0), of the alkali halides. Ag halides and TI halides, with the nearest neighbor distances, d(sub nn). First, we show that the product E(sub coh)d(sub 0) within families of halide crystals with common crystal structure is to a good approximation constant, with maximum rms deviation of plus or minus 2%. Secondly, we demonstrate that within families of halide crystals with a common cation and common crystal structure the product B(sub 0)d(sup 3.5)(sub nn) is a good approximation constant, with maximum rms deviation of plus or minus 1.36%.

  8. Measuring Boltzmann's Constant with Carbon Dioxide

    ERIC Educational Resources Information Center

    Ivanov, Dragia; Nikolov, Stefan

    2013-01-01

    In this paper we present two experiments to measure Boltzmann's constant--one of the fundamental constants of modern-day physics, which lies at the base of statistical mechanics and thermodynamics. The experiments use very basic theory, simple equipment and cheap and safe materials yet provide very precise results. They are very easy and…

  9. Recommended Values of the Fundamental Physical Constants: A Status Report

    PubMed Central

    Taylor, Barry N.; Cohen, E. Richard

    1990-01-01

    We summarize the principal advances made in the fundamental physical constants field since the completion of the 1986 CODATA least-squares adjustment of the constants and discuss their implications for both the 1986 set of recommended values and the next least-squares adjustment. In general, the new results lead to values of the constants with uncertainties 5 to 7 times smaller than the uncertainties assigned the 1986 values. However, the changes in the values themselves are less than twice the 1986 assigned one-standard-deviation uncertainties and thus are not highly significant. Although much new data has become available since 1986, three new results dominate the analysis: a value of the Planck constant obtained from a realization of the watt; a value of the fine-structure constant obtained from the magnetic moment anomaly of the electron; and a value of the molar gas constant obtained from the speed of sound in argon. Because of their dominant role in determining the values and uncertainties of many of the constants, it is highly desirable that additional results of comparable uncertainty that corroborate these three data items be obtained before the next adjustment is carried out. Until then, the 1986 CODATA set of recommended values will remain the set of choice. PMID:28179787

  10. Optimal Server Scheduling to Maintain Constant Customer Waiting Times

    DTIC Science & Technology

    1988-12-01

    I I• I I I I I LCn CN OPTIMAL SERVER SCHEDUUNG TO MAINTAIN CONSTANT CUSTOMER WAITING TIMES THESIS Thomas J. Frey Captain UISAF AFIT/GOR/ENS/88D-7...hw bees appsewlf in ple rtan. cd = , ’ S 087 AFIT/GORMENS/8D-7 OPTIMAL SERVER SCHEDUUNG TO MAINTAIN~ CONSTANT CUSTOMER WAITING TIMES THESIS Thomas j...CONSTANT CUSTOMER WAITING TIMES THESIS Presented to the Faculty of the School of Engineering of the Air Force Institute of Technology Air University In

  11. Optimal plane change during constant altitude hypersonic flight

    NASA Technical Reports Server (NTRS)

    Mease, K. D.; Vinh, N. X.; Kuo, S. H.

    1988-01-01

    Future spacecraft operating in the vicinity of the earth may have resort to the atmosphere as an aid in effecting orbital change. While a previous treatment of this technique chose constant altitude, speed, and angle-of-attack values in order to maximize the plane change for a fixed amount of propellant consumption during hypersonic flight, the former two parameters are presently released from the constraint of constancy. The general characteristics of the optimal controls are described on the basis of the domain of maneuverability, and numerical solutions are obtained for several specific cases. Under the condition of constant-altitude flight, it is generally not optimal to fly at constant angle-of-attack.

  12. Compilation of Henry's law constants, version 3.99

    NASA Astrophysics Data System (ADS)

    Sander, R.

    2014-11-01

    Many atmospheric chemicals occur in the gas phase as well as in liquid cloud droplets and aerosol particles. Therefore, it is necessary to understand the distribution between the phases. According to Henry's law, the equilibrium ratio between the abundances in the gas phase and in the aqueous phase is constant for a dilute solution. Henry's law constants of trace gases of potential importance in environmental chemistry have been collected and converted into a uniform format. The compilation contains 14775 values of Henry's law constants for 3214 species, collected from 639 references. It is also available on the internet at http://www.henrys-law.org.

  13. Our Universe from the cosmological constant

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

    Barrau, Aurélien; Linsefors, Linda, E-mail: Aurelien.Barrau@cern.ch, E-mail: linda.linsefors@lpsc.in2p3.fr

    The issue of the origin of the Universe and of its contents is addressed in the framework of bouncing cosmologies, as described for example by loop quantum gravity. If the current acceleration is due to a true cosmological constant, this constant is naturally conserved through the bounce and the Universe should also be in a (contracting) de Sitter phase in the remote past. We investigate here the possibility that the de Sitter temperature in the contracting branch fills the Universe with radiation that causes the bounce and the subsequent inflation and reheating. We also consider the possibility that this givesmore » rise to a cyclic model of the Universe and suggest some possible tests.« less

  14. Planck's Constant as a Natural Unit of Measurement

    ERIC Educational Resources Information Center

    Quincey, Paul

    2013-01-01

    The proposed revision of SI units would embed Planck's constant into the definition of the kilogram, as a fixed constant of nature. Traditionally, Planck's constant is not readily interpreted as the size of something physical, and it is generally only encountered by students in the mathematics of quantum physics. Richard Feynman's…

  15. A 90 day chronic toxicity study of Nigerian herbal preparation DAS-77 in rats

    PubMed Central

    2012-01-01

    Background The herbal preparation DAS-77, used for the treatment of various ailments in Nigeria, contains the milled bark of Mangifera indica L. and root of Carica papaya L. Toxicological assessment of the preparation was carried out in this study. Methods In the acute toxicity study, DAS-77 was administered to mice p.o. up to 20 g/kg in divided doses and i.p. at 250–3000 mg/kg. Mortality within 24 h was recorded. In the chronic toxicity study, rats were treated p.o. for 90 days at doses of 80, 400 (therapeutic dose, TD) and 2000 mg/kg. By 90 days, animals were sacrificed and blood samples collected for hematological and biochemical analysis. Organs were harvested for weight determination, antioxidants and histopathological assessments. Results DAS-77 did not produce any lethality administered p.o. up to 20 g/kg in divided doses but the i.p. LD50 was 1122.0 mg/kg. At TD, DAS-77 produced significant (p < 0.05) reductions in body weight, food intake and K+, and increases in ovary weight, neutrophils and HDL, which were reversible. Histopathological presentations were generally normal. Effects at the other doses were comparable to those at TD except for reversible increases in antioxidants in the liver, kidney and testes, and sperm abnormality, and reductions in liver enzymes, sperm motility and count. Conclusions Findings in this study revealed that DAS-77 is relatively safe with the potential for enhancing in vivo antioxidant activity. However, possibly reversible side-effects include electrolyte imbalance and sterility in males. PMID:22892317

  16. A 90 day chronic toxicity study of Nigerian herbal preparation DAS-77 in rats.

    PubMed

    Afolabi, Saheed O; Akindele, Abidemi J; Awodele, Olufunsho; Anunobi, Chidozie C; Adeyemi, Olufunmilayo O

    2012-06-28

    The herbal preparation DAS-77, used for the treatment of various ailments in Nigeria, contains the milled bark of Mangifera indica L. and root of Carica papaya L. Toxicological assessment of the preparation was carried out in this study. In the acute toxicity study, DAS-77 was administered to mice p.o. up to 20 g/kg in divided doses and i.p. at 250-3000 mg/kg. Mortality within 24 h was recorded. In the chronic toxicity study, rats were treated p.o. for 90 days at doses of 80, 400 (therapeutic dose, TD) and 2000 mg/kg. By 90 days, animals were sacrificed and blood samples collected for hematological and biochemical analysis. Organs were harvested for weight determination, antioxidants and histopathological assessments. DAS-77 did not produce any lethality administered p.o. up to 20 g/kg in divided doses but the i.p. LD50 was 1122.0 mg/kg. At TD, DAS-77 produced significant (p < 0.05) reductions in body weight, food intake and K+, and increases in ovary weight, neutrophils and HDL, which were reversible. Histopathological presentations were generally normal. Effects at the other doses were comparable to those at TD except for reversible increases in antioxidants in the liver, kidney and testes, and sperm abnormality, and reductions in liver enzymes, sperm motility and count. Findings in this study revealed that DAS-77 is relatively safe with the potential for enhancing in vivo antioxidant activity. However, possibly reversible side-effects include electrolyte imbalance and sterility in males.

  17. Atomic weights: no longer constants of nature

    USGS Publications Warehouse

    Coplen, Tyler B.; Holden, Norman E.

    2011-01-01

    Many of us were taught that the standard atomic weights we found in the back of our chemistry textbooks or on the Periodic Table of the Chemical Elements hanging on the wall of our chemistry classroom are constants of nature. This was common knowledge for more than a century and a half, but not anymore. The following text explains how advances in chemical instrumentation and isotopic analysis have changed the way we view atomic weights and why they are no longer constants of nature

  18. Vacuum-Assisted, Constant-Force Exercise Device

    NASA Technical Reports Server (NTRS)

    Hansen, Christopher P.; Jensen, Scott

    2006-01-01

    The vacuum-assisted, constant-force exercise device (VAC-FED) has been proposed to fill a need for a safe, reliable exercise machine that would provide constant loads that could range from 20 to 250 lb (0.09 to 1.12 kN) with strokes that could range from 6 to 36 in. (0.15 to 0.91 m). The VAC-FED was originally intended to enable astronauts in microgravity to simulate the lifting of free weights, but it could just as well be used on Earth for simulated weight lifting and other constant-force exercises. Because the VAC-FED would utilize atmospheric/vacuum differential pressure instead of weights to generate force, it could weigh considerably less than either a set of free weights or a typical conventional exercise machine based on weights. Also, the use of atmospheric/ vacuum differential pressure to generate force would render the VAC-FED inherently safer, relative to free weights and to conventional exercise machines that utilize springs to generate forces. The overall function of the VAC-FED would be to generate a constant tensile force in an output cable, which would be attached to a bar, handle, or other exercise interface. The primary force generator in the VAC-FED would be a piston in a cylinder. The piston would separate a volume vented to atmosphere at one end of the cylinder from an evacuated volume at the other end of the cylinder (see figure). Hence, neglecting friction at the piston seals, the force generated would be nearly constant equal to the area of the piston multiplied by the atmospheric/vacuum differential pressure. In the vented volume in the cylinder, a direct-force cable would be looped around a pulley on the piston, doubling the stroke and halving the tension. One end of the direct-force cable would be anchored to a cylinder cap; the other end of the direct-force cable would be wrapped around a variable-ratio pulley that would couple tension to the output cable. As its name suggests, the variable-ratio pulley would contain a mechanism that

  19. Stress-stress fluctuation formula for elastic constants in the NPT ensemble

    NASA Astrophysics Data System (ADS)

    Lips, Dominik; Maass, Philipp

    2018-05-01

    Several fluctuation formulas are available for calculating elastic constants from equilibrium correlation functions in computer simulations, but the ones available for simulations at constant pressure exhibit slow convergence properties and cannot be used for the determination of local elastic constants. To overcome these drawbacks, we derive a stress-stress fluctuation formula in the NPT ensemble based on known expressions in the NVT ensemble. We validate the formula in the NPT ensemble by calculating elastic constants for the simple nearest-neighbor Lennard-Jones crystal and by comparing the results with those obtained in the NVT ensemble. For both local and bulk elastic constants we find an excellent agreement between the simulated data in the two ensembles. To demonstrate the usefulness of the formula, we apply it to determine the elastic constants of a simulated lipid bilayer.

  20. Das CARNOTsche Paradigma und seine erkenntnistheoretischen Implikationen

    NASA Astrophysics Data System (ADS)

    Schöpf, Hans-Georg

    Der vorliegende historisch-kritische Essay führt die Eigentümlichkeiten der klassischen phänomenologischen Thermodynamik auf das von CARNOT geschaffene Paradigma zurück und greift einige damit zusammenhängende Fragen auf.Translated AbstractCARNOT's Paradigm and its Epistemological ImplicationsThe present historic-critical essay traces the pecularities of classical phenomenological thermodynamics back to the paradigm, created by CARNOT, and takes up some questions to which this paradigm gives rise.

  1. Temperature and size-dependent Hamaker constants for metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Jiang, K.; Pinchuk, P.

    2016-08-01

    Theoretical values of the Hamaker constant have been calculated for metal nanoparticles using Lifshitz theory. The theory describes the Hamaker constant in terms of the permittivity of the interacting bodies. Metal nanoparticles exhibit an internal size effect that alters the dielectric permittivity of the particle when its size falls below the mean free path of the conducting electrons. This size dependence of the permittivity leads to size-dependence of the Hamaker constant for metal nanoparticles. Additionally, the electron damping and the plasma frequency used to model the permittivity of the particle exhibit temperature-dependence, which lead to temperature dependence of the Hamaker constant. In this work, both the size and temperature dependence for gold, silver, copper, and aluminum nanoparticles is demonstrated. The results of this study might be of interest for studying the colloidal stability of nanoparticles in solution.

  2. Temperature and size-dependent Hamaker constants for metal nanoparticles.

    PubMed

    Jiang, K; Pinchuk, P

    2016-08-26

    Theoretical values of the Hamaker constant have been calculated for metal nanoparticles using Lifshitz theory. The theory describes the Hamaker constant in terms of the permittivity of the interacting bodies. Metal nanoparticles exhibit an internal size effect that alters the dielectric permittivity of the particle when its size falls below the mean free path of the conducting electrons. This size dependence of the permittivity leads to size-dependence of the Hamaker constant for metal nanoparticles. Additionally, the electron damping and the plasma frequency used to model the permittivity of the particle exhibit temperature-dependence, which lead to temperature dependence of the Hamaker constant. In this work, both the size and temperature dependence for gold, silver, copper, and aluminum nanoparticles is demonstrated. The results of this study might be of interest for studying the colloidal stability of nanoparticles in solution.

  3. Fundamental Insight on Developing Low Dielectric Constant Polyimides

    NASA Technical Reports Server (NTRS)

    Simpson, J. O.; SaintClair, A. K.

    1997-01-01

    Thermally stable, durable, insulative polyimides are in great demand for the fabrication of microelectronic devices. In this investigation dielectric and optical properties have been studied for several series of aromatic polyimides. The effect of polarizability, fluorine content, and free volume on dielectric constant was examined. In general, minimizing polarizability, maximizing free volume and fluorination all lowered dielectric constants in the polyimides studied.

  4. Do migratory flight paths of raptors follow constant geographical or geomagnetic courses?

    USGS Publications Warehouse

    Thorup, K.; Fuller, M.; Alerstam, T.; Hake, M.; Kjellen, N.; Strandberg, R.

    2006-01-01

    We tested whether routes of raptors migrating over areas with homogeneous topography follow constant geomagnetic courses more or less closely than constant geographical courses. We analysed the routes taken over land of 45 individual raptors tracked by satellite-based radiotelemetry: 25 peregrine falcons, Falco peregrinus, on autumn migration between North and South America, and seven honey buzzards, Pernis apivorus, and 13 ospreys, Pandion haliaetus, on autumn migration between Europe and Africa. Overall, migration directions showed a better agreement with constant geographical than constant geomagnetic courses. Tracks deviated significantly from constant geomagnetic courses, but were not significantly different from geographical courses. After we removed movements directed far from the mean direction, which may not be migratory movements, migration directions still showed a better agreement with constant geographical than constant geomagnetic courses, but the directions of honey buzzards and ospreys were not significantly different from constant geomagnetic courses either. That migration routes of raptors followed by satellite telemetry are in closer accordance with constant geographical compass courses than with constant geomagnetic compass courses may indicate that geographical (e.g. based on celestial cues) rather than magnetic compass mechanisms are of dominating importance for the birds' long-distance orientation.

  5. The SeaDAS Processing and Analysis System: SeaWiFS, MODIS, and Beyond

    NASA Astrophysics Data System (ADS)

    MacDonald, M. D.; Ruebens, M.; Wang, L.; Franz, B. A.

    2005-12-01

    The SeaWiFS Data Analysis System (SeaDAS) is a comprehensive software package for the processing, display, and analysis of ocean data from a variety of satellite sensors. Continuous development and user support by programmers and scientists for more than a decade has helped to make SeaDAS the most widely used software package in the world for ocean color applications, with a growing base of users from the land and sea surface temperature community. Full processing support for past (CZCS, OCTS, MOS) and present (SeaWiFS, MODIS) sensors, and anticipated support for future missions such as NPP/VIIRS, enables end users to reproduce the standard ocean archive product suite distributed by NASA's Ocean Biology Processing Group (OBPG), as well as a variety of evaluation and intermediate ocean, land, and atmospheric products. Availability of the processing algorithm source codes and a software build environment also provide users with the tools to implement custom algorithms. Recent SeaDAS enhancements include synchronization of MODIS processing with the latest code and calibration updates from the MODIS Calibration Support Team (MCST), support for all levels of MODIS processing including Direct Broadcast, a port to the Macintosh OS X operating system, release of the display/analysis-only SeaDAS-Lite, and an extremely active web-based user support forum.

  6. Can compactifications solve the cosmological constant problem?

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

    Hertzberg, Mark P.; Center for Theoretical Physics, Department of Physics,Massachusetts Institute of Technology,77 Massachusetts Ave, Cambridge, MA 02139; Masoumi, Ali

    2016-06-30

    Recently, there have been claims in the literature that the cosmological constant problem can be dynamically solved by specific compactifications of gravity from higher-dimensional toy models. These models have the novel feature that in the four-dimensional theory, the cosmological constant Λ is much smaller than the Planck density and in fact accumulates at Λ=0. Here we show that while these are very interesting models, they do not properly address the real cosmological constant problem. As we explain, the real problem is not simply to obtain Λ that is small in Planck units in a toy model, but to explain whymore » Λ is much smaller than other mass scales (and combinations of scales) in the theory. Instead, in these toy models, all other particle mass scales have been either removed or sent to zero, thus ignoring the real problem. To this end, we provide a general argument that the included moduli masses are generically of order Hubble, so sending them to zero trivially sends the cosmological constant to zero. We also show that the fundamental Planck mass is being sent to zero, and so the central problem is trivially avoided by removing high energy physics altogether. On the other hand, by including various large mass scales from particle physics with a high fundamental Planck mass, one is faced with a real problem, whose only known solution involves accidental cancellations in a landscape.« less

  7. Degravitation of the cosmological constant in bigravity

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

    Platscher, Moritz; Smirnov, Juri, E-mail: moritz.platscher@mpi-hd.mpg.de, E-mail: juri.smirnov@mpi-hd.mpg.de

    2017-03-01

    In this article the phenomenon of degravitation of the cosmological constant is studied in the framework of bigravity. It is demonstrated that despite a sizable value of the cosmological constant its gravitational effect can be only mild. The bigravity framework is chosen for this demonstration as it leads to a consistent, ghost-free theory of massive gravity. We show that degravitation takes place in the limit where the physical graviton is dominantly a gauge invariant metric combination. We present and discuss several phenomenological consequences expected in this regime.

  8. Identification of elastic, dielectric, and piezoelectric constants in piezoceramic disks.

    PubMed

    Perez, Nicolas; Andrade, Marco A B; Buiochi, Flavio; Adamowski, Julio C

    2010-12-01

    Three-dimensional modeling of piezoelectric devices requires a precise knowledge of piezoelectric material parameters. The commonly used piezoelectric materials belong to the 6mm symmetry class, which have ten independent constants. In this work, a methodology to obtain precise material constants over a wide frequency band through finite element analysis of a piezoceramic disk is presented. Given an experimental electrical impedance curve and a first estimate for the piezoelectric material properties, the objective is to find the material properties that minimize the difference between the electrical impedance calculated by the finite element method and that obtained experimentally by an electrical impedance analyzer. The methodology consists of four basic steps: experimental measurement, identification of vibration modes and their sensitivity to material constants, a preliminary identification algorithm, and final refinement of the material constants using an optimization algorithm. The application of the methodology is exemplified using a hard lead zirconate titanate piezoceramic. The same methodology is applied to a soft piezoceramic. The errors in the identification of each parameter are statistically estimated in both cases, and are less than 0.6% for elastic constants, and less than 6.3% for dielectric and piezoelectric constants.

  9. Elastic Constants of Ni-Mn-Ga Magnetic Shape Memory Alloys

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

    Stipcich, M.; Manosa, L.; Planes, A.

    2004-01-01

    We have measured the adiabatic second order elastic constants of two Ni-Mn-Ga magnetic shape memory crystals with different martensitic transition temperatures, using ultrasonic methods. The temperature dependence of the elastic constants has been followed across the ferromagnetic transition and down to the martensitic transition temperature. Within experimental errors no noticeable change in any of the elastic constants has been observed at the Curie point. The temperature dependence of the shear elastic constant C' has been found to be very different for the two alloys. Such a different behavior is in agreement with recent theoretical predictions for systems undergoing multi-stage structuralmore » transitions.« less

  10. Fluctuations, ghosts, and the cosmological constant

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

    Hirayama, T.; Holdom, B.

    2004-12-15

    For a large region of parameter space involving the cosmological constant and mass parameters, we discuss fluctuating spacetime solutions that are effectively Minkowskian on large time and distance scales. Rapid, small amplitude oscillations in the scale factor have a frequency determined by the size of a negative cosmological constant. A field with modes of negative energy is required. If it is gravity that induces a coupling between the ghostlike and normal fields, we find that this results in stochastic rather than unstable behavior. The negative energy modes may also permit the existence of Lorentz invariant fluctuating solutions of finite energymore » density. Finally we consider higher derivative gravity theories and find oscillating metric solutions in these theories without the addition of other fields.« less

  11. LAMMPS Implementation of Constant Energy Dissipative Particle Dynamics (DPD-E)

    DTIC Science & Technology

    2014-03-01

    LAMMPS Implementation of Constant Energy Dissipative Particle Dynamics (DPD-E) by James P. Larentzos, John K. Brennan, Joshua D. Moore, and...MD 21005-5069 ARL-TR-6863 March 2014 LAMMPS Implementation of Constant Energy Dissipative Particle Dynamics (DPD-E) James P...13 September 2013 4. TITLE AND SUBTITLE LAMMPS Implementation of Constant Energy Dissipative Particle Dynamics (DPD-E) 5a. CONTRACT NUMBER 5b

  12. Brady's Geothermal Field - Map of DAS, Nodal, Vibroseis and Reftek Station Deployment

    DOE Data Explorer

    Kurt Feigl

    2016-10-15

    Map of DAS, nodal, vibroseis and Reftek stations during March 2016 deployment. The plot on the left has nodal stations labeled; the plot on the right has vibroseis observations labeled. Stations are shown in map-view using Brady's rotated X-Y coordinates with side plots denoting elevation with respect to the WGS84 ellipsoid. Blue circles denote vibroseis data, x symbols denote DAS (cyan for horizontal and magenta for vertical), black asterisks denote Reftek data, and red plus signs denote nodal data. This map can be found on UW-Madison's askja server at /PoroTomo/DATA/MAPS/Deployment_Stations.pdf

  13. Simple Model with Time-Varying Fine-Structure ``Constant''

    NASA Astrophysics Data System (ADS)

    Berman, M. S.

    2009-10-01

    Extending the original version written in colaboration with L.A. Trevisan, we study the generalisation of Dirac's LNH, so that time-variation of the fine-structure constant, due to varying electrical and magnetic permittivities is included along with other variations (cosmological and gravitational ``constants''), etc. We consider the present Universe, and also an inflationary scenario. Rotation of the Universe is a given possibility in this model.

  14. Energy consumption analysis of constant voltage and constant current operations in capacitive deionization

    DOE PAGES

    Qu, Yatian; Campbell, Patrick G.; Gu, Lei; ...

    2016-09-21

    Here we report our studies to compare energy consumption of a CDI cell in constant voltage (CV) and constant current (CC) operations, with a focus on understanding the underlying physics of consumption patterns. The comparison is conducted under conditions that the CV and CC operations result in the same amounts of input charge and within identical charging phase durations. We present two electrical circuit models to simulate energy consumption in charging phase: one is a simple RC circuit model, and the other a transmission line circuit model. We built and tested a CDI cell to validate the transmission line model,more » and performed a series of experiments to compare CV versus CC operation under the condition of equal applied charge and charging duration. The experiments show that CC mode consumes energy at 33.8 kJ per mole of ions removed, which is only 28% of CV mode energy consumption (120.6 kJ/mol), but achieves similar level of salt removals. Lastly, together, the models and experiment support our major conclusion that CC is more energy efficient than CV for equal charge and charging duration. The models also suggest that the lower energy consumption of CC in charging is due to its lower resistive dissipation.« less

  15. Energy consumption analysis of constant voltage and constant current operations in capacitive deionization

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

    Qu, Yatian; Campbell, Patrick G.; Gu, Lei

    Here we report our studies to compare energy consumption of a CDI cell in constant voltage (CV) and constant current (CC) operations, with a focus on understanding the underlying physics of consumption patterns. The comparison is conducted under conditions that the CV and CC operations result in the same amounts of input charge and within identical charging phase durations. We present two electrical circuit models to simulate energy consumption in charging phase: one is a simple RC circuit model, and the other a transmission line circuit model. We built and tested a CDI cell to validate the transmission line model,more » and performed a series of experiments to compare CV versus CC operation under the condition of equal applied charge and charging duration. The experiments show that CC mode consumes energy at 33.8 kJ per mole of ions removed, which is only 28% of CV mode energy consumption (120.6 kJ/mol), but achieves similar level of salt removals. Lastly, together, the models and experiment support our major conclusion that CC is more energy efficient than CV for equal charge and charging duration. The models also suggest that the lower energy consumption of CC in charging is due to its lower resistive dissipation.« less

  16. Base units of the SI, fundamental constants and modern quantum physics.

    PubMed

    Bordé, Christian J

    2005-09-15

    Over the past 40 years, a number of discoveries in quantum physics have completely transformed our vision of fundamental metrology. This revolution starts with the frequency stabilization of lasers using saturation spectroscopy and the redefinition of the metre by fixing the velocity of light c. Today, the trend is to redefine all SI base units from fundamental constants and we discuss strategies to achieve this goal. We first consider a kinematical frame, in which fundamental constants with a dimension, such as the speed of light c, the Planck constant h, the Boltzmann constant k(B) or the electron mass m(e) can be used to connect and redefine base units. The various interaction forces of nature are then introduced in a dynamical frame, where they are completely characterized by dimensionless coupling constants such as the fine structure constant alpha or its gravitational analogue alpha(G). This point is discussed by rewriting the Maxwell and Dirac equations with new force fields and these coupling constants. We describe and stress the importance of various quantum effects leading to the advent of this new quantum metrology. In the second part of the paper, we present the status of the seven base units and the prospects of their possible redefinitions from fundamental constants in an experimental perspective. The two parts can be read independently and they point to these same conclusions concerning the redefinitions of base units. The concept of rest mass is directly related to the Compton frequency of a body, which is precisely what is measured by the watt balance. The conversion factor between mass and frequency is the Planck constant, which could therefore be fixed in a realistic and consistent new definition of the kilogram based on its Compton frequency. We discuss also how the Boltzmann constant could be better determined and fixed to replace the present definition of the kelvin.

  17. Time variation of fundamental constants in nonstandard cosmological models

    NASA Astrophysics Data System (ADS)

    Mosquera, M. E.; Civitarese, O.

    2017-10-01

    In this work we have studied the lithium problem in nonstandard cosmological models. In particular, by using the public code alterbbn, we have included in the computation of the primordial light nuclei abundances, the effects of the inclusion of dark energy and dark entropy, along with the variation of the fine structure constant and the Higgs vacuum expectation value. In order to set constrains on the variation of the fundamental constants we have compared our theoretical results with the available observational data. We have found that the lithium abundance is reduced for not-null variation at the 3 σ -level of both constants.

  18. Automated real time constant-specificity surveillance for disease outbreaks.

    PubMed

    Wieland, Shannon C; Brownstein, John S; Berger, Bonnie; Mandl, Kenneth D

    2007-06-13

    For real time surveillance, detection of abnormal disease patterns is based on a difference between patterns observed, and those predicted by models of historical data. The usefulness of outbreak detection strategies depends on their specificity; the false alarm rate affects the interpretation of alarms. We evaluate the specificity of five traditional models: autoregressive, Serfling, trimmed seasonal, wavelet-based, and generalized linear. We apply each to 12 years of emergency department visits for respiratory infection syndromes at a pediatric hospital, finding that the specificity of the five models was almost always a non-constant function of the day of the week, month, and year of the study (p < 0.05). We develop an outbreak detection method, called the expectation-variance model, based on generalized additive modeling to achieve a constant specificity by accounting for not only the expected number of visits, but also the variance of the number of visits. The expectation-variance model achieves constant specificity on all three time scales, as well as earlier detection and improved sensitivity compared to traditional methods in most circumstances. Modeling the variance of visit patterns enables real-time detection with known, constant specificity at all times. With constant specificity, public health practitioners can better interpret the alarms and better evaluate the cost-effectiveness of surveillance systems.

  19. Planck Constant Determination from Power Equivalence

    NASA Astrophysics Data System (ADS)

    Newell, David B.

    2000-04-01

    Equating mechanical to electrical power links the kilogram, the meter, and the second to the practical realizations of the ohm and the volt derived from the quantum Hall and the Josephson effects, yielding an SI determination of the Planck constant. The NIST watt balance uses this power equivalence principle, and in 1998 measured the Planck constant with a combined relative standard uncertainty of 8.7 x 10-8, the most accurate determination to date. The next generation of the NIST watt balance is now being assembled. Modification to the experimental facilities have been made to reduce the uncertainty components from vibrations and electromagnetic interference. A vacuum chamber has been installed to reduce the uncertainty components associated with performing the experiment in air. Most of the apparatus is in place and diagnostic testing of the balance should begin this year. Once a combined relative standard uncertainty of one part in 10-8 has been reached, the power equivalence principle can be used to monitor the possible drift in the artifact mass standard, the kilogram, and provide an accurate alternative definition of mass in terms of fundamental constants. *Electricity Division, Electronics and Electrical Engineering Laboratory, Technology Administration, U.S. Department of Commerce. Contribution of the National Institute of Standards and Technology, not subject to copyright in the U.S.

  20. Calculation of individual isotope equilibrium constants for implementation in geochemical models

    USGS Publications Warehouse

    Thorstenson, Donald C.; Parkhurst, David L.

    2002-01-01

    Theory is derived from the work of Urey to calculate equilibrium constants commonly used in geochemical equilibrium and reaction-transport models for reactions of individual isotopic species. Urey showed that equilibrium constants of isotope exchange reactions for molecules that contain two or more atoms of the same element in equivalent positions are related to isotope fractionation factors by , where is n the number of atoms exchanged. This relation is extended to include species containing multiple isotopes, for example and , and to include the effects of nonideality. The equilibrium constants of the isotope exchange reactions provide a basis for calculating the individual isotope equilibrium constants for the geochemical modeling reactions. The temperature dependence of the individual isotope equilibrium constants can be calculated from the temperature dependence of the fractionation factors. Equilibrium constants are calculated for all species that can be formed from and selected species containing , in the molecules and the ion pairs with where the subscripts g, aq, l, and s refer to gas, aqueous, liquid, and solid, respectively. These equilibrium constants are used in the geochemical model PHREEQC to produce an equilibrium and reaction-transport model that includes these isotopic species. Methods are presented for calculation of the individual isotope equilibrium constants for the asymmetric bicarbonate ion. An example calculates the equilibrium of multiple isotopes among multiple species and phases.

  1. Global Gridded Data from the Goddard Earth Observing System Data Assimilation System (GEOS-DAS)

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The Goddard Earth Observing System Data Assimilation System (GEOS-DAS) timeseries is a globally gridded atmospheric data set for use in climate research. This near real-time data set is produced by the Data Assimilation Office (DAO) at the NASA Goddard Space Flight Center in direct support of the operational EOS instrument product generation from the Terra (12/1999 launch), Aqua (05/2002 launch) and Aura (01/2004 launch) spacecrafts. The data is archived in the EOS Core System (ECS) at the Goddard Earth Sciences Data and Information Services Center/Distributed Active Archive Center (GES DISC DAAC). The data is only a selection of the products available from the GEOS-DAS. The data is organized chronologically in timeseries format to facilitate the computation of statistics. GEOS-DAS data will be available for the time period January 1, 2000, through present.

  2. The Rate Constant for Fluorescence Quenching

    ERIC Educational Resources Information Center

    Legenza, Michael W.; Marzzacco, Charles J.

    1977-01-01

    Describes an experiment that utilizes fluorescence intensity measurements from a Spectronic 20 to determine the rate constant for the fluorescence quenching of various aromatic hydrocarbons by carbon tetrachloride in an ethanol solvent. (MLH)

  3. Measuring Primary Teachers' Attitudes Toward Teaching Science: Development of the Dimensions of Attitude Toward Science (DAS) Instrument

    NASA Astrophysics Data System (ADS)

    van Aalderen-Smeets, Sandra; Walma van der Molen, Juliette

    2013-03-01

    In this article, we present a valid and reliable instrument which measures the attitude of in-service and pre-service primary teachers toward teaching science, called the Dimensions of Attitude Toward Science (DAS) Instrument. Attention to the attitudes of primary teachers toward teaching science is of fundamental importance to the professionalization of these teachers in the field of primary science education. With the development of this instrument, we sought to fulfill the need for a statistically and theoretically valid and reliable instrument to measure pre-service and in-service teachers' attitudes. The DAS Instrument is based on a comprehensive theoretical framework for attitude toward (teaching) science. After pilot testing, the DAS was revised and subsequently validated using a large group of respondents (pre-service and in-service primary teachers) (N = 556). The theoretical underpinning of the DAS combined with the statistical data indicate that the DAS possesses good construct validity and that it proves to be a promising instrument that can be utilized for research purposes, and also as a teacher training and coaching tool. This instrument can therefore make a valuable contribution to progress within the field of science education.

  4. Brady's Geothermal Field DAS Vibroseis Data

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

    Kurt Feigl

    2016-03-25

    The submitted data correspond to the monitored vibrations caused by a vibroseis seismically exciting the ground in the vertical direction and captured by the DAS horizontal and vertical arrays during the PoroTomo Experiment. The data also include a file with the acceleration record at the Vibroseis. Vibroseis Sweep Details: Sweep on location T84 Stage 4 (Mode P 60 s long record ) Time: 2016-03-25 14:01:15 (UTC) Location: 39.80476089N, -119.0027625W Elevation: 1272.0M (on ground surface at the site) Sweep length: 20 seconds Frequencies: 5 Hz to 20 Hz

  5. Efficient Delivery and Visualization of Long Time-Series Datasets Using Das2 Tools

    NASA Astrophysics Data System (ADS)

    Piker, C.; Granroth, L.; Faden, J.; Kurth, W. S.

    2017-12-01

    For over 14 years the University of Iowa Radio and Plasma Wave Group has utilized a network transparent data streaming and visualization system for most daily data review and collaboration activities. This system, called Das2, was originally designed in support of the Cassini Radio and Plasma Wave Science (RPWS) investigation, but is now relied on for daily review and analysis of Voyager, Polar, Cluster, Mars Express, Juno and other mission results. In light of current efforts to promote automatic data distribution in space physics it seems prudent to provide an overview of our open source Das2 programs and interface definitions to the wider community and to recount lessons learned. This submission will provide an overview of interfaces that define the system, describe the relationship between the Das2 effort and Autoplot and will examine handling Cassini RPWS Wideband waveforms and dynamic spectra as examples of dealing with long time-series data sets. In addition, the advantages and limitations of the current Das2 tool set will be discussed, as well as lessons learned that are applicable to other data sharing initiatives. Finally, plans for future developments including improved catalogs to support 'no-software' data sources and redundant multi-server fail over, as well as new adapters for CSV (Comma Separated Values) and JSON (Javascript Object Notation) output to support Cassini closeout and the HAPI (Heliophysics Application Programming Interface) initiative are outlined.

  6. Comparison of entrainment in constant volume and constant flux dense currents over sloping bottoms

    NASA Astrophysics Data System (ADS)

    Bhaganagar, K.; Nayamatullah, M.; Cenedese, C.

    2014-12-01

    Three dimensional high resolution large eddy simulations (LES) are employed to simulate lock-exchange and constant flux dense flows over inclined surface with the aim of investigating, visualizing and describing the turbulent structure and the evolution of bottom-propagating compositional density current at the channel bottom. The understanding of dynamics of density current is largely determined by the amount of interfacial mixing or entrainment between the ambient and dense fluids. No previous experimental or numerical studies have been done to estimate entrainment in classical lock-exchange system. The differences in entrainment between the lock-exchange and constant flux are explored. Comparing the results of flat bed with inclined surface results, flow exhibits significant differences near the leading edge or nose of the front of the density currents due to inclination of surface. Further, the instabilities are remarkably enhanced resulting Kelvin-Helmholtz and lobe-cleft type of instabilities arises much earlier in time. In this study, a brief analysis of entrainment on lock-exchange density current is presented using different bed slopes and a set of reduced gravity values (g'). We relate the entrainment value with different flow parameters such as Froude number (Fr) and Reynolds number (Re).

  7. A causa das estações do ano: modelos mentais

    NASA Astrophysics Data System (ADS)

    de Campos, J. A. S.; de Araujo, J. F. S.

    2003-08-01

    A década de 70 do século passado foi marcada pelo estudo das concepções alternativas que os alunos trazem para a sala de aula. A identificação destas concepções foi o ponto de partida para promover a mudança conceitual, onde as pré-concepções seriam trocadas pelas concepções científicas. Na década seguinte, surgiram muitas propostas de estratégias educacionais para facilitar esta troca, na sua maioria baseadas na idéia do conflito cognitivo, proposta por Piaget. Entretanto, os resultados pouco animadores conduziram à percepção de que a mudança conceitual é um processo mais complexo. Pelas idéias da Ciência Cognitiva, a mudança conceitual é uma mudança progressiva dos modelos mentais que o aluno tem sobre o mundo físico, através de enriquecimento e revisão. A causa das Estações do Ano é um tópico sobre o qual a maioria dos estudantes apresenta concepções alternativas. Os autores fizeram um levantamento sobre as pré-concepções encontradas em trabalhos sobre o tema (16 referências), procurando encontrar elementos comuns que indicassem a presença de modelos mentais específicos. As pré-concepções encontradas na literatura foram obtidas usando-se diversas metodologias (desde entrevistas clínicas até questionários de múltipla escolha) e envolvendo alunos e professores de diferentes regiões geográficas. A partir de uma análise aprofundada de cada trabalho, e utilizando-se a técnica das Redes Sistêmicas, chegou-se a conclusão que as diversas pré-concepções identificadas (em torno de 50), poderiam ser representadas por 6 modelos mentais, onde a explicação da causa das estações do ano tem um mecanismo causal responsável. Os mecanismos causais identificados foram: a dependência da distância, a dependência da orientação, a dependência conjunta da distância e orientação, a dependência da obstrução, a dependência da velocidade e a dependência da inclinação dos raios solares. Foram ainda identificadas

  8. Safety evaluation of genetically modified DAS-40278-9 maize in a subchronic rodent feeding study.

    PubMed

    Zou, Shiying; Lang, Tianqi; Liu, Xu; Huang, Kunlun; He, Xiaoyun

    2018-07-01

    Genetically modified (GM) maize, DAS-40278-9, expresses the aryloxyalkanoate dioxygenase-1 (AAD-1) protein, which confers tolerance to 2,4-dichlorophenoxyacetic acid (2,4-D) and aryloxyphenoxypropionate (AOPP) herbicides. The aad-1 gene, which expresses the AAD-1 protein, was derived from Gram-negative soil bacterium, Sphingobium herbicidovorans. A 90-day sub-chronic toxicity study was conducted on rats as a component of the safety evaluation of DAS-40278-9 maize. Rats were given formulated diets containing maize grain from DAS-40278-9 or a non-GM near isogenic control comparator at an incorporation rate of 12.5%, 25%, or 50% (w/w), respectively for 90 days. In addition, another group of rats was fed a basic rodent diet. Animals were evaluated by cage-side and hand-held detailed clinical observations, ophthalmic examinations, body weights/body weight gains, feed consumption, hematology, serum chemistry, selected organ weights, and gross and histopathological examinations. Under the condition of this study, DAS-40278-9 maize did not cause any treatment-related effects in rats compared with rats fed diets containing non-GM maize. Copyright © 2018 Elsevier Inc. All rights reserved.

  9. Using Constant Time Delay to Teach Braille Word Recognition

    ERIC Educational Resources Information Center

    Hooper, Jonathan; Ivy, Sarah; Hatton, Deborah

    2014-01-01

    Introduction: Constant time delay has been identified as an evidence-based practice to teach print sight words and picture recognition (Browder, Ahlbrim-Delzell, Spooner, Mims, & Baker, 2009). For the study presented here, we tested the effectiveness of constant time delay to teach new braille words. Methods: A single-subject multiple baseline…

  10. Revision of an automated microseismic location algorithm for DAS - 3C geophone hybrid array

    NASA Astrophysics Data System (ADS)

    Mizuno, T.; LeCalvez, J.; Raymer, D.

    2017-12-01

    Application of distributed acoustic sensing (DAS) has been studied in several areas in seismology. One of the areas is microseismic reservoir monitoring (e.g., Molteni et al., 2017, First Break). Considering the present limitations of DAS, which include relatively low signal-to-noise ratio (SNR) and no 3C polarization measurements, a DAS - 3C geophone hybrid array is a practical option when using a single monitoring well. Considering the large volume of data from distributed sensing, microseismic event detection and location using a source scanning type algorithm is a reasonable choice, especially for real-time monitoring. The algorithm must handle both strain rate along the borehole axis for DAS and particle velocity for 3C geophones. Only a small quantity of large SNR events will be detected throughout a large aperture encompassing the hybrid array; therefore, the aperture is to be optimized dynamically to eliminate noisy channels for a majority of events. For such hybrid array, coalescence microseismic mapping (CMM) (Drew et al., 2005, SPE) was revised. CMM forms a likelihood function of location of event and its origin time. At each receiver, a time function of event arrival likelihood is inferred using an SNR function, and it is migrated to time and space to determine hypocenter and origin time likelihood. This algorithm was revised to dynamically optimize such a hybrid array by identifying receivers where a microseismic signal is possibly detected and using only those receivers to compute the likelihood function. Currently, peak SNR is used to select receivers. To prevent false results due to small aperture, a minimum aperture threshold is employed. The algorithm refines location likelihood using 3C geophone polarization. We tested this algorithm using a ray-based synthetic dataset. Leaney (2014, PhD thesis, UBC) is used to compute particle velocity at receivers. Strain rate along the borehole axis is computed from particle velocity as DAS microseismic

  11. Wave propagation in and around negative-dielectric-constant discharge plasma

    NASA Astrophysics Data System (ADS)

    Sakai, Osamu; Iwai, Akinori; Omura, Yoshiharu; Iio, Satoshi; Naito, Teruki

    2018-03-01

    The modes of wave propagation in media with a negative dielectric constant are not simple, unlike those for electromagnetic waves in media with a positive dielectric constant (where modes propagate inside the media with positive phase velocity since the refractive index is usually positive). Instead, they depend on the permeability sign, either positive or negative, and exhibit completely different features. In this report, we investigated a wave confined on the surface of a negative-dielectric-constant and a positive-permeability plasma medium for which the refractive index is imaginary. The propagation mode is similar to surface plasmon polaritons on the metal containing free electrons, but its frequency band is different due to the significant spatial gradient of the dielectric constant and a different pressure term. We also studied a wave with a negative dielectric constant and negative permeability, where the refractive index is negative. This wave can propagate inside the media, but its phase velocity is negative. It also shares similar qualities with waves in plasmonic devices with negative permeability in the photon range.

  12. Strong resetting of the mammalian clock by constant light followed by constant darkness

    PubMed Central

    Chen, Rongmin; Seo, Dong-oh; Bell, Elijah; von Gall, Charlotte; Lee, Choogon

    2008-01-01

    The mammalian molecular circadian clock in the suprachiasmatic nuclei (SCN) regulates locomotor activity rhythms as well as clocks in peripheral tissues (Reppert and Weaver, 2002; Ko and Takahashi, 2006). Constant light (LL) can induce behavioral and physiological arrhythmicity, by desynchronizing clock cells in the SCN (Ohta et al., 2005). We examined how the disordered clock cells resynchronize by probing the molecular clock and measuring behavior in mice transferred from LL to constant darkness (DD). The circadian locomotor activity rhythms disrupted in LL become robustly rhythmic again from the beginning of DD, and the starting phase of the rhythm in DD is specific, not random, suggesting that the desynchronized clock cells are quickly reset in an unconventional manner by the L:D transition. By measuring mPERIOD protein rhythms, we showed that the SCN and peripheral tissue clocks quickly become rhythmic again in phase with the behavioral rhythms. We propose that this resetting mechanism may be different from conventional phase shifting, which involves light-induction of Period genes (Albrecht et al., 1997; Shearman et al., 1997; Shigeyoshi et al., 1997). Using our functional insights, we could shift the circadian phase of locomotor activity rhythms by 12 hours using a 15-hour LL treatment: essentially producing phase reversal by a single light pulse, a feat that has not been reported previously in wild-type mice and that has potential clinical utility. PMID:19005049

  13. Assimilation of SBUV Version 8 Radiances into the GEOS Ozone DAS

    NASA Technical Reports Server (NTRS)

    Mueller, Martin D.; Stajner, Ivanka; Bhartia, Pawan K.

    2004-01-01

    In operational weather forecasting, the assimilation of brightness temperatures from satellite sounders, instead of assimilation of 1D-retrievals has become increasingly common practice over the last two decades. Compared to these systems, assimilation of trace gases is still at a relatively early stage of development, and efforts to directly assimilate radiances instead of retrieved products have just begun a few years ago, partially because it requires much more computation power due to the employment of a radiative transport forward model (FM). This paper will focus on a method to assimilate SBUV/2 radiances (albedos) into the Global Earth Observation System Ozone Data Assimilation Scheme (GEOS-03DAS). While SBUV-type instruments cannot compete with newer sensors in terms of spectral and horizontal resolution, they feature a continuous data record back to 1978, which makes them very valuable for trend studies. Assimilation can help spreading their ground coverage over the whole globe, as has been previously demonstrated with the GEOS-03DAS using SBUV Version 6 ozone profiles. Now, the DAS has been updated to use the newly released SBUV Version 8 data. We will compare pre]lmlnarv results of SBUV radiance assimilation with the assimilation of retrieved ozone profiles, discuss methods to deal with the increased computational load, and try to assess the error characteristics and future potential of the new approach.

  14. Cantilever spring constant calibration using laser Doppler vibrometry

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

    Ohler, Benjamin

    2007-06-15

    Uncertainty in cantilever spring constants is a critical issue in atomic force microscopy (AFM) force measurements. Though numerous methods exist for calibrating cantilever spring constants, the accuracy of these methods can be limited by both the physical models themselves as well as uncertainties in their experimental implementation. Here we report the results from two of the most common calibration methods, the thermal tune method and the Sader method. These were implemented on a standard AFM system as well as using laser Doppler vibrometry (LDV). Using LDV eliminates some uncertainties associated with optical lever detection on an AFM. It also offersmore » considerably higher signal to noise deflection measurements. We find that AFM and LDV result in similar uncertainty in the calibrated spring constants, about 5%, using either the thermal tune or Sader methods provided that certain limitations of the methods and instrumentation are observed.« less

  15. Instanton rate constant calculations close to and above the crossover temperature.

    PubMed

    McConnell, Sean; Kästner, Johannes

    2017-11-15

    Canonical instanton theory is known to overestimate the rate constant close to a system-dependent crossover temperature and is inapplicable above that temperature. We compare the accuracy of the reaction rate constants calculated using recent semi-classical rate expressions to those from canonical instanton theory. We show that rate constants calculated purely from solving the stability matrix for the action in degrees of freedom orthogonal to the instanton path is not applicable at arbitrarily low temperatures and use two methods to overcome this. Furthermore, as a by-product of the developed methods, we derive a simple correction to canonical instanton theory that can alleviate this known overestimation of rate constants close to the crossover temperature. The combined methods accurately reproduce the rate constants of the canonical theory along the whole temperature range without the spurious overestimation near the crossover temperature. We calculate and compare rate constants on three different reactions: H in the Müller-Brown potential, methylhydroxycarbene → acetaldehyde and H 2  + OH → H + H 2 O. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  16. Imaging nanoclusters in the constant height mode of the dynamic SFM.

    PubMed

    Barth, Clemens; Pakarinen, Olli H; Foster, Adam S; Henry, Claude R

    2006-04-14

    For the first time, high quality images of metal nanoclusters which were recorded in the constant height mode of a dynamic scanning force microscope (dynamic SFM) are shown. Surfaces of highly ordered pyrolytic graphite (HOPG) were used as a test substrate since metal nanoclusters with well defined and symmetric shapes can be created by epitaxial growth. We performed imaging of gold clusters with sizes between 5 and 15 nm in both scanning modes, constant Δf mode and constant height mode, and compared the image contrast. We notice that clusters in constant height images appear much sharper, and exhibit more reasonable lateral shapes and sizes in comparison to images recorded in the constant Δf mode. With the help of numerical simulations we show that only a microscopically small part of the tip apex (nanotip) is probably the main contributor for the image contrast formation. In principle, the constant height mode can be used for imaging surfaces of any material, e.g. ionic crystals, as shown for the system Au/NaCl(001).

  17. Variable energy constant current accelerator structure

    DOEpatents

    Anderson, O.A.

    1988-07-13

    A variable energy, constant current ion beam accelerator structure is disclosed comprising an ion source capable of providing the desired ions, a pre-accelerator for establishing an initial energy level, a matching/pumping module having means for focusing means for maintaining the beam current, and at least one main accelerator module for continuing beam focus, with means capable of variably imparting acceleration to the beam so that a constant beam output current is maintained independent of the variable output energy. In a preferred embodiment, quadrupole electrodes are provided in both the matching/pumping module and the one or more accelerator modules, and are formed using four opposing cylinder electrodes which extend parallel to the beam axis and are spaced around the beam at 90/degree/ intervals with opposing electrodes maintained at the same potential. 12 figs., 3 tabs.

  18. Einfluss des Internets auf das Informations-, Einkaufs- und Verkehrsverhalten

    NASA Astrophysics Data System (ADS)

    Nerlich, Mark R.; Schiffner, Felix; Vogt, Walter

    Mit Daten aus eigenen Erhebungen können das einkaufsbezogene Informations- und Einkaufsverhalten im Zusammenhang mit den verkehrlichen Aspekten (Distanzen, Verkehrsmittel, Wegekopplungen) dargestellt werden. Die Differenzierung in die drei Produktkategorien des täglichen, mittelfristigen und des langfristigen Bedarfs berücksichtigt in erster Linie die Wertigkeit eines Gutes, die seine Erwerbshäufigkeit unmittelbar bestimmt. Der Einsatz moderner IKT wie das Internet eröffnet dem Endverbraucher neue Möglichkeiten bei Information und Einkauf. Die verkehrliche Relevanz von Online-Shopping wird deutlich, wenn man berücksichtigt, dass im Mittel rund 17% aller Online-Einkäufe, die die Probanden durchgeführt haben, Einkäufe in Ladengeschäften ersetzen. Dies gilt in verstärktem Maße für Online-Informationen: etwa die Hälfte hätte alternativ im stationären Einzelhandel stattgefunden. Da der Erwerb von Gütern des täglichen Bedarfs häufig nahräumlich und in relevantem Anteil nicht-motorisiert erfolgen kann, sind in diesem Segment - im Gegensatz zum mittel- und langfristigen Bedarf - nur geringe Substitutionseffekte zu beobachten.

  19. Dielectric constants of soils at microwave frequencies

    NASA Technical Reports Server (NTRS)

    Geiger, F. E.; Williams, D.

    1972-01-01

    A knowledge of the complex dielectric constant of soils is essential in the interpretation of microwave airborne radiometer data of the earth's surface. Measurements were made at 37 GHz on various soils from the Phoenix, Ariz., area. Extensive data have been obtained for dry soil and soil with water content in the range from 0.6 to 35 percent by dry weight. Measurements were made in a two arm microwave bridge and results were corrected for reflections at the sample interfaces by solution of the parallel dielectric plate problem. The maximum dielectric constants are about a factor of 3 lower than those reported for similar soils at X-band frequencies.

  20. Further thoughts on the solar constant

    NASA Astrophysics Data System (ADS)

    Thompson, Frank

    2018-05-01

    I read with interest the recent paper (Brizova and Slegr 2017 Phys. Educ. 52 013008) regarding an experiment to measure the solar constant using a bolometer. The authors admitted that their measurements gave a value much lower than expected.

  1. Rate constants measured for hydrated electron reactions with peptides and proteins

    NASA Technical Reports Server (NTRS)

    Braams, R.

    1968-01-01

    Effects of ionizing radiation on the amino acids of proteins and the reactivity of the protonated amino group depends upon the pK subscript a of the group. Estimates of the rate constants for reactions involving the amino acid side chains are presented. These rate constants gave an approximate rate constant for three different protein molecules.

  2. An adaptive-binning method for generating constant-uncertainty/constant-significance light curves with Fermi -LAT data

    DOE PAGES

    Lott, B.; Escande, L.; Larsson, S.; ...

    2012-07-19

    Here, we present a method enabling the creation of constant-uncertainty/constant-significance light curves with the data of the Fermi-Large Area Telescope (LAT). The adaptive-binning method enables more information to be encapsulated within the light curve than with the fixed-binning method. Although primarily developed for blazar studies, it can be applied to any sources. Furthermore, this method allows the starting and ending times of each interval to be calculated in a simple and quick way during a first step. The reported mean flux and spectral index (assuming the spectrum is a power-law distribution) in the interval are calculated via the standard LATmore » analysis during a second step. In the absence of major caveats associated with this method Monte-Carlo simulations have been established. We present the performance of this method in determining duty cycles as well as power-density spectra relative to the traditional fixed-binning method.« less

  3. Optical constants of electroplated gold from spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Synowicki, R. A.; Herzinger, Craig M.; Hall, James T.; Malingowski, Andrew

    2017-11-01

    The optical constants of an opaque electroplated gold film (Laser Gold from Epner Technology Inc.), were determined by spectroscopic ellipsometry at room temperature over the spectral range from 0.142 μm in the vacuum ultraviolet to 36 μm in the infrared (photon energy range 0.034-8.75 eV). Data from two separate ellipsometer instruments covering different spectral ranges were analyzed simultaneously. The optical constants n&k or ε1&ε2 were determined by fitting an oscillator dispersion model combining Drude, Gaussian, and Sellmeier dispersion functions to the experimental Ψ and Δ data. The data were analyzed using both an ideal bulk substrate model and a simple overlayer model to account for surface roughness. Including the optical surface roughness layer improved ellipsometric data fits in the UV, and using a separate Drude function for the surface layer improved fits in the infrared. The surface roughness was also characterized using an Atomic Force Microscope. Using an oscillator dispersion model for the optical constants determined in this work allows for more realistic extrapolation to longer infrared wavelengths. Extending optical constants out to 50 μm and beyond is important for calibrating far-infrared reflectance measurements. Applications include understanding the thermal performance of cryogenic space-based instruments, such as the James Webb Space Telescope (JWST).

  4. Distributed Acoustic Sensing (DAS) for Periodic Hydraulic Tests: Laboratory Data

    DOE Data Explorer

    Coleman, Thomas

    2015-02-27

    These data were collected in the laboratory located at California State University Long Beach. They consist of DAS data collected from a fiber optic cable placed in a tank of water, subjected to oscillating head. These tests are described in the article linked below.

  5. Conjugate Acid-Base Pairs, Free Energy, and the Equilibrium Constant

    ERIC Educational Resources Information Center

    Beach, Darrell H.

    1969-01-01

    Describes a method of calculating the equilibrium constant from free energy data. Values of the equilibrium constants of six Bronsted-Lowry reactions calculated by the author's method and by a conventional textbook method are compared. (LC)

  6. Free energy perturbation method for measuring elastic constants of liquid crystals

    NASA Astrophysics Data System (ADS)

    Joshi, Abhijeet

    There is considerable interest in designing liquid crystals capable of yielding specific morphological responses in confined environments, including capillaries and droplets. The morphology of a liquid crystal is largely dictated by the elastic constants, which are difficult to measure and are only available for a handful of substances. In this work, a first-principles based method is proposed to calculate the Frank elastic constants of nematic liquid crystals directly from atomistic models. These include the standard splay, twist and bend deformations, and the often-ignored but important saddle-splay constant. The proposed method is validated using a well-studied Gay-Berne(3,5,2,1) model; we examine the effects of temperature and system size on the elastic constants in the nematic and smectic phases. We find that our measurements of splay, twist, and bend elastic constants are consistent with previous estimates for the nematic phase. We further outline the implementation of our approach for the saddle-splay elastic constant, and find it to have a value at the limits of the Ericksen inequalities. We then proceed to report results for the elastic constants commonly known liquid crystals namely 4-pentyl-4'-cynobiphenyl (5CB) using atomistic model, and show that the values predicted by our approach are consistent with a subset of the available but limited experimental literature.

  7. Caregivers as Teachers: Using Constant Time Delay To Teach Adults How To Use Constant Time Delay.

    ERIC Educational Resources Information Center

    Wall, Maureen E.; Gast, David L.

    1997-01-01

    A study involving four caregivers evaluated the effectiveness of a systematic instructional procedure known as constant time delay (CTD) in teaching caregivers how to use CTD to teach their adolescent or adult children, siblings, or clients with disabilities, response chain skills. Results found the procedure to be effective. (CR)

  8. Fine structure constant defines visual transparency of graphene.

    PubMed

    Nair, R R; Blake, P; Grigorenko, A N; Novoselov, K S; Booth, T J; Stauber, T; Peres, N M R; Geim, A K

    2008-06-06

    There are few phenomena in condensed matter physics that are defined only by the fundamental constants and do not depend on material parameters. Examples are the resistivity quantum, h/e2 (h is Planck's constant and e the electron charge), that appears in a variety of transport experiments and the magnetic flux quantum, h/e, playing an important role in the physics of superconductivity. By and large, sophisticated facilities and special measurement conditions are required to observe any of these phenomena. We show that the opacity of suspended graphene is defined solely by the fine structure constant, a = e2/hc feminine 1/137 (where c is the speed of light), the parameter that describes coupling between light and relativistic electrons and that is traditionally associated with quantum electrodynamics rather than materials science. Despite being only one atom thick, graphene is found to absorb a significant (pa = 2.3%) fraction of incident white light, a consequence of graphene's unique electronic structure.

  9. An Inverse Square Law Variation for Hubble's Constant

    NASA Astrophysics Data System (ADS)

    Day, Orville W., Jr.

    1999-11-01

    The solution to Einstein's gravitational field equations is examined, using a Robertson-Walker metric with positive curvature, when Hubble's parameter, H_0, is taken to be a constant divided by R^2. R is the cosmic scale factor for the universe treated as a three-dimensional hypersphere in a four-dimensional Euclidean space. This solution produces a self-energy of the universe, W^(0)_self, proportional to the square of the total mass, times the universal gravitational constant divided by the cosmic scale factor, R. This result is totally analogous to the self-energy of the electromagnetic field of a charged particle, W^(0)_self = ke^2/2r, where the total charge e is squared, k is the universal electric constant and r is the scale factor, usually identified as the radius of the particle. It is shown that this choice for H0 leads to physically meaningful results for the average mass density and pressure, and a deacceleration parameter q_0=1.

  10. Median statistics estimates of Hubble and Newton's constants

    NASA Astrophysics Data System (ADS)

    Bethapudi, Suryarao; Desai, Shantanu

    2017-02-01

    Robustness of any statistics depends upon the number of assumptions it makes about the measured data. We point out the advantages of median statistics using toy numerical experiments and demonstrate its robustness, when the number of assumptions we can make about the data are limited. We then apply the median statistics technique to obtain estimates of two constants of nature, Hubble constant (H0) and Newton's gravitational constant ( G , both of which show significant differences between different measurements. For H0, we update the analyses done by Chen and Ratra (2011) and Gott et al. (2001) using 576 measurements. We find after grouping the different results according to their primary type of measurement, the median estimates are given by H0 = 72.5^{+2.5}_{-8} km/sec/Mpc with errors corresponding to 95% c.l. (2 σ) and G=6.674702^{+0.0014}_{-0.0009} × 10^{-11} Nm2kg-2 corresponding to 68% c.l. (1σ).

  11. Design verification of large time constant thermal shields for optical reference cavities.

    PubMed

    Zhang, J; Wu, W; Shi, X H; Zeng, X Y; Deng, K; Lu, Z H

    2016-02-01

    In order to achieve high frequency stability in ultra-stable lasers, the Fabry-Pérot reference cavities shall be put inside vacuum chambers with large thermal time constants to reduce the sensitivity to external temperature fluctuations. Currently, the determination of thermal time constants of vacuum chambers is based either on theoretical calculation or time-consuming experiments. The first method can only apply to simple system, while the second method will take a lot of time to try out different designs. To overcome these limitations, we present thermal time constant simulation using finite element analysis (FEA) based on complete vacuum chamber models and verify the results with measured time constants. We measure the thermal time constants using ultrastable laser systems and a frequency comb. The thermal expansion coefficients of optical reference cavities are precisely measured to reduce the measurement error of time constants. The simulation results and the experimental results agree very well. With this knowledge, we simulate several simplified design models using FEA to obtain larger vacuum thermal time constants at room temperature, taking into account vacuum pressure, shielding layers, and support structure. We adopt the Taguchi method for shielding layer optimization and demonstrate that layer material and layer number dominate the contributions to the thermal time constant, compared with layer thickness and layer spacing.

  12. 50 CFR 648.53 - Acceptable biological catch (ABC), annual catch limits (ACL), annual catch targets (ACT), DAS...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... catch limits (ACL), annual catch targets (ACT), DAS allocations, and individual fishing quotas (IFQ... limits (ACL), annual catch targets (ACT), DAS allocations, and individual fishing quotas (IFQ). (a... process specified in § 648.55 and is equal to the overall scallop fishery ACL. The ABC/ACL shall be...

  13. 50 CFR 648.53 - Acceptable biological catch (ABC), annual catch limits (ACL), annual catch targets (ACT), DAS...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... catch limits (ACL), annual catch targets (ACT), DAS allocations, and individual fishing quotas (IFQ... limits (ACL), annual catch targets (ACT), DAS allocations, and individual fishing quotas (IFQ). (a... process specified in § 648.55 and is equal to the overall scallop fishery ACL. The ABC/ACL shall be...

  14. Variations of the Solar Constant. [conference

    NASA Technical Reports Server (NTRS)

    Sofia, S. (Editor)

    1981-01-01

    The variations in data received from rocket-borne and balloon-borne instruments are discussed. Indirect techniques to measure and monitor the solar constant are presented. Emphasis is placed on the correlation of data from the Solar Maximum Mission and the Nimbus 7 satellites.

  15. Boson mapping techniques applied to constant gauge fields in QCD

    NASA Technical Reports Server (NTRS)

    Hess, Peter Otto; Lopez, J. C.

    1995-01-01

    Pairs of coordinates and derivatives of the constant gluon modes are mapped to new gluon-pair fields and their derivatives. Applying this mapping to the Hamiltonian of constant gluon fields results for large coupling constants into an effective Hamiltonian which separates into one describing a scalar field and another one for a field with spin two. The ground state is dominated by pairs of gluons coupled to color and spin zero with slight admixtures of color zero and spin two pairs. As color group we used SU(2).

  16. The Hubble Constant.

    PubMed

    Jackson, Neal

    2007-01-01

    I review the current state of determinations of the Hubble constant, which gives the length scale of the Universe by relating the expansion velocity of objects to their distance. In the last 20 years, much progress has been made and estimates now range between 60 and 75 km s -1 Mpc -1 , with most now between 70 and 75 km s -1 Mpc -1 , a huge improvement over the factor-of-2 uncertainty which used to prevail. Further improvements which gave a generally agreed margin of error of a few percent rather than the current 10% would be vital input to much other interesting cosmology. There are several programmes which are likely to lead us to this point in the next 10 years.

  17. Teaching Foreign Cultural Literacy with Margarethe von Trotta's "Das Versprechen"

    ERIC Educational Resources Information Center

    Kuttenberg, Eva

    2003-01-01

    This article describes model units for an in-depth cultural analysis of "Das Versprechen" in undergraduate college courses including intermediate German, German culture and civilization, advanced conversation and composition, and film. Practical suggestions for pre-viewing, viewing, and post-viewing activities as well as assessment in…

  18. [Grades evaluation of Phellodendri chinensis cortex pieces based on quality constant].

    PubMed

    Deng, Zhe; Jiao, Meng-Jiao; Zhang, Jun; Zhang, Qing; Cui, Wen-Jin; Shen, Li; Cheng, Jin-Tang; Liu, An

    2017-09-01

    Quality constant is a comprehensive grades evaluation method for traditional Chinese medicine decoction pieces, which is better but based on traditional way. In this paper, a new grading mode for Phellodendri chinensis pieces was established based on quality constant evaluation method. The results showed that the range of relative quality constant for 15 batches of different samples was from 0.41 to 0.96. As customary, if these samples were divided into three grades: the relative quality constant shall be ≥0.77 for first grade; <0.77 but ≥0.48 for the second grade; and <0.48 for the third grade. This research indicated that the quality constant mode can be used to effectively grade the P. chinensis pieces in a scientific, reasonable, objective and specific way. Simultaneously, it provided a beneficial reference for grading cortex herbal pieces or medicines. Copyright© by the Chinese Pharmaceutical Association.

  19. Determination of Henry’s Law Constants Using Internal Standards with Benchmark Values

    EPA Science Inventory

    It is shown that Henry’s law constants can be experimentally determined by comparing headspace content of compounds with known constants to interpolate the constants of other compounds. Studies were conducted over a range of water temperatures to identify temperature dependence....

  20. Constant mean curvature slicings of Kantowski-Sachs spacetimes

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

    Heinzle, J. Mark

    2011-04-15

    We investigate existence, uniqueness, and the asymptotic properties of constant mean curvature (CMC) slicings in vacuum Kantowski-Sachs spacetimes with positive cosmological constant. Since these spacetimes violate the strong energy condition, most of the general theorems on CMC slicings do not apply. Although there are in fact Kantowski-Sachs spacetimes with a unique CMC foliation or CMC time function, we prove that there also exist Kantowski-Sachs spacetimes with an arbitrary number of (families of) CMC slicings. The properties of these slicings are analyzed in some detail.

  1. Optical constants of liquid and solid methane

    NASA Technical Reports Server (NTRS)

    Martonchik, John V.; Orton, Glenn S.

    1994-01-01

    The optical constants n(sub r) + in(sub i) of liquid methane and phase 1 solid methane were determined over the entire spectral range by the use of various data sources published in the literature. Kramers-Kronig analyses were performed on the absorption spectra of liquid methane at the boiling point (111 K) and the melting point (90 K) and on the absorption spectra of phase 1 solid methane at the melting point and at 30 K. Measurements of the static dielectric constant at these temperatures and refractive indices determined over limited spectral ranges were used as constraints in the analyses. Applications of methane optical properties to studies of outer solar system bodies are described.

  2. In vitro and in vivo comparisons of constant resistance AC iontophoresis and DC iontophoresis.

    PubMed

    Li, S Kevin; Higuchi, William I; Zhu, Honggang; Kern, Steven E; Miller, David J; Hastings, Matthew S

    2003-09-04

    A previous in vitro constant electrical resistance alternating current (AC) iontophoresis study with human epidermal membrane (HEM) and a model neutral permeant has shown less inter- and intra-sample variability in iontophoretic transport relative to conventional constant direct current (DC) iontophoresis. The objectives of the present study were to address the following questions. (1) Can the skin electrical resistance be maintained at a constant level by AC in humans in vivo? (2) Are the in vitro data with HEM representative of those in vivo? (3) Does constant skin resistance AC iontophoresis have less inter- and intra-sample variability than conventional constant current DC iontophoresis in vivo? (4) What are the electrical and the barrier properties of skin during iontophoresis in vivo? In the present study, in vitro HEM experiments were carried out with the constant resistance AC and the conventional constant current DC methods using mannitol and glucose as the neutral model permeants. In vivo human experiments were performed using glucose as the permeant with a constant skin resistance AC only protocol and two conventional constant current DC methods (continuous constant current DC and constant current DC with its polarity alternated every 10 min with a 3:7 on:off duty cycle). Constant current DC iontophoresis was conducted with commercial constant current DC devices, and constant resistance AC iontophoresis was carried out by reducing and maintaining the skin resistance at a constant target value with AC supplied from a function generator. This study shows that (1) skin electrical resistance can be maintained at a constant level during AC iontophoresis in vivo; (2) HEM in vitro and human skin in vivo demonstrate similar electrical and barrier properties, and these properties are consistent with our previous findings; (3) there is general qualitative and semi-quantitative agreement between the HEM data in vitro and human skin data in vivo; and (4) constant

  3. [Pleural mesothelioma in a school teacher: asbestos exposure due to DAS paste].

    PubMed

    Barbieri, Pietro Gino; Somigliana, Anna; Girelli, Roberto; Lombardi, Sandra; Sarnico, Michela; Silvestri, Stefano

    2016-03-24

    Malignant mesothelioma cases among primary school teachers are usually linked with asbestos exposure due to the mineral contained in the building structure. Among the approximately 12,000 cases of mesothelioma described in the fourth report of the National Mesothelioma Register, 11 cases of primary school teachers are reported, in spite of the fact that the "catalogue of asbestos use" does not describe circumstances of asbestos exposure other than or different to that due to asbestos contained in the buildings. Four cases in the Brescia Provincial Mesothelioma Register are identified as teachers, without this circumstance of exposure. To characterize the asbestos concentration and fibre type retained in the lungs of a teacher reported as a new mesothelioma case and preliminarily classified as of unknown asbestos exposure. The mesothelioma case presented here was diagnosed at age 78 and malignant mesothelioma was confirmed at autopsy; the patient was interviewed directly for occupational history. Samples of lung parenchyma from necropsies were collected, stored and analyzed by scanning electron microscope (SEM) and samples of DAS paste were analyzed by SEM to detect asbestos fibre content. It was possible to confirm past exposure to DAS paste in forming and finishing dry items and toys during school recreational activity almost every day from the mid-60s to about the mid-70s. Subsequent SEM analysis showed: i) chrysotile fibres were found in an old and unused pack of DAS paste; ii) a lung burden of 1,400 asbestos bodies, 310.000 total asbestos fibres (33% chrysotile, 67% amphibole) and 210.000 talc fibre per gr/dry lung tissue was detected from necropsies performed on the subject. These results seem to be in agreement with an occupational exposure to asbestos due to past use of DAS paste. After the investigation, this case was reclassified from "unknowun" to " sure" occupational asbestos exposure. The occupational origin of the tumour was recognized by the Italian

  4. Estimation of hydrolysis rate constants for carbamates ...

    EPA Pesticide Factsheets

    Cheminformatics based tools, such as the Chemical Transformation Simulator under development in EPA’s Office of Research and Development, are being increasingly used to evaluate chemicals for their potential to degrade in the environment or be transformed through metabolism. Hydrolysis represents a major environmental degradation pathway; unfortunately, only a small fraction of hydrolysis rates for about 85,000 chemicals on the Toxic Substances Control Act (TSCA) inventory are in public domain, making it critical to develop in silico approaches to estimate hydrolysis rate constants. In this presentation, we compare three complementary approaches to estimate hydrolysis rates for carbamates, an important chemical class widely used in agriculture as pesticides, herbicides and fungicides. Fragment-based Quantitative Structure Activity Relationships (QSARs) using Hammett-Taft sigma constants are widely published and implemented for relatively simple functional groups such as carboxylic acid esters, phthalate esters, and organophosphate esters, and we extend these to carbamates. We also develop a pKa based model and a quantitative structure property relationship (QSPR) model, and evaluate them against measured rate constants using R square and root mean square (RMS) error. Our work shows that for our relatively small sample size of carbamates, a Hammett-Taft based fragment model performs best, followed by a pKa and a QSPR model. This presentation compares three comp

  5. Diffusional falsification of kinetic constants on Lineweaver-Burk plots.

    PubMed

    Ghim, Y S; Chang, H N

    1983-11-07

    The effect of mass transfer resistances on the Lineweaver-Burk plots in immobilized enzyme systems has been investigated numerically and with analytical approximate solutions. While Hamilton, Gardner & Colton (1974) studied the effect of internal diffusion resistances in planar geometry, our study was extended to the combined effect of internal and external diffusion in cylindrical and spherical geometries as well. The variation of Lineweaver-Burk plots with respect to the geometries was minimized by modifying the Thiele modulus and the Biot number with the shape factor. Especially for a small Biot number all the three Lineweaver-Burk plots fell on a single line. As was discussed by Hamilton et al. (1974), the curvature of the line for large external diffusion resistances was small enough to be assumed linear, which was confirmed from the two approximate solutions for large and small substrate concentrations. Two methods for obtaining intrinsic kinetic constants were proposed: First, we obtained both maximum reaction rate and Michaelis constant by fitting experimental data to a straight line where external diffusion resistance was relatively large, and second, we obtained Michaelis constant from apparent Michaelis constant from the figure in case we knew maximum reaction rate a priori.

  6. Incorporating Parallel Computing into the Goddard Earth Observing System Data Assimilation System (GEOS DAS)

    NASA Technical Reports Server (NTRS)

    Larson, Jay W.

    1998-01-01

    Atmospheric data assimilation is a method of combining actual observations with model forecasts to produce a more accurate description of the earth system than the observations or forecast alone can provide. The output of data assimilation, sometimes called the analysis, are regular, gridded datasets of observed and unobserved variables. Analysis plays a key role in numerical weather prediction and is becoming increasingly important for climate research. These applications, and the need for timely validation of scientific enhancements to the data assimilation system pose computational demands that are best met by distributed parallel software. The mission of the NASA Data Assimilation Office (DAO) is to provide datasets for climate research and to support NASA satellite and aircraft missions. The system used to create these datasets is the Goddard Earth Observing System Data Assimilation System (GEOS DAS). The core components of the the GEOS DAS are: the GEOS General Circulation Model (GCM), the Physical-space Statistical Analysis System (PSAS), the Observer, the on-line Quality Control (QC) system, the Coupler (which feeds analysis increments back to the GCM), and an I/O package for processing the large amounts of data the system produces (which will be described in another presentation in this session). The discussion will center on the following issues: the computational complexity for the whole GEOS DAS, assessment of the performance of the individual elements of GEOS DAS, and parallelization strategy for some of the components of the system.

  7. I/O Parallelization for the Goddard Earth Observing System Data Assimilation System (GEOS DAS)

    NASA Technical Reports Server (NTRS)

    Lucchesi, Rob; Sawyer, W.; Takacs, L. L.; Lyster, P.; Zero, J.

    1998-01-01

    The National Aeronautics and Space Administration (NASA) Data Assimilation Office (DAO) at the Goddard Space Flight Center (GSFC) has developed the GEOS DAS, a data assimilation system that provides production support for NASA missions and will support NASA's Earth Observing System (EOS) in the coming years. The GEOS DAS will be used to provide background fields of meteorological quantities to EOS satellite instrument teams for use in their data algorithms as well as providing assimilated data sets for climate studies on decadal time scales. The DAO has been involved in prototyping parallel implementations of the GEOS DAS for a number of years and is now embarking on an effort to convert the production version from shared-memory parallelism to distributed-memory parallelism using the portable Message-Passing Interface (MPI). The GEOS DAS consists of two main components, an atmospheric General Circulation Model (GCM) and a Physical-space Statistical Analysis System (PSAS). The GCM operates on data that are stored on a regular grid while PSAS works with observational data that are scattered irregularly throughout the atmosphere. As a result, the two components have different data decompositions. The GCM is decomposed horizontally as a checkerboard with all vertical levels of each box existing on the same processing element(PE). The dynamical core of the GCM can also operate on a rotated grid, which requires communication-intensive grid transformations during GCM integration. PSAS groups observations on PEs in a more irregular and dynamic fashion.

  8. A comparison of constant-load and constant-deflection stress-corrosion tests on precracked DCB specimens. [Double Cantilever Beam

    NASA Technical Reports Server (NTRS)

    Dorward, R. C.; Hasse, K. R.

    1978-01-01

    A comparison is made between measurements of stress-corrosion crack propagation made by a constant-load procedure and by a constant-deflection procedure. Precracked double cantilever beam specimens from 7075 aluminum alloy plate were used. The specimens were oriented in such a way that cracking would begin in the short-transverse plane and would propagate in the rolling direction. The specimens were subjected to a buffered salt-chromate solution and a 3.6% synthetic sea salt solution. The measurements were made optically with a binocular microscope. Stress intensities and crack lengths were calculated and crack velocities were obtained. Velocity was plotted against the average calculated stress intensity. Good agreement between the two methods was found for the salt-chromate solution, although some descrepancies were noted for the artificial sea salt solution.

  9. The Dependence of the Spring Constant in the Linear Range on Spring Parameters

    ERIC Educational Resources Information Center

    Khotimah, Siti Nurul; Viridi, Sparisoma; Widayani; Khairurrijal

    2011-01-01

    In basic physics laboratories, springs are normally used to determine both spring constants and the Earth's gravitational acceleration. Students generally do not notice that the spring constant is not a universal constant, but depends on the spring parameters. This paper shows and verifies that the spring constant in the linear range is inversely…

  10. Spray Gun With Constant Mixing Ratio

    NASA Technical Reports Server (NTRS)

    Simpson, William G.

    1987-01-01

    Conceptual mechanism mounted in handle of spray gun maintains constant ratio between volumetric flow rates in two channels leading to spray head. With mechanism, possible to keep flow ratio near 1:1 (or another desired ratio) over range of temperatures, orifice or channel sizes, or clogging conditions.

  11. Large numbers hypothesis. IV - The cosmological constant and quantum physics

    NASA Technical Reports Server (NTRS)

    Adams, P. J.

    1983-01-01

    In standard physics quantum field theory is based on a flat vacuum space-time. This quantum field theory predicts a nonzero cosmological constant. Hence the gravitational field equations do not admit a flat vacuum space-time. This dilemma is resolved using the units covariant gravitational field equations. This paper shows that the field equations admit a flat vacuum space-time with nonzero cosmological constant if and only if the canonical LNH is valid. This allows an interpretation of the LNH phenomena in terms of a time-dependent vacuum state. If this is correct then the cosmological constant must be positive.

  12. Kny Coupling Constants and Form Factors from the Chiral Bag Model

    NASA Astrophysics Data System (ADS)

    Jeong, M. T.; Cheon, Il-T.

    2000-09-01

    The form factors and coupling constants for KNΛ and KNΣ interactions have been calculated in the framework of the Chiral Bag Model with vector mesons. Taking into account vector meson (ρ, ω, K*) field effects, we find -3.88 ≤ gKNΛ ≤ -3.67 and 1.15 ≤ gKNΣ ≤ 1.24, where the quark-meson coupling constants are determined by fitting the renormalized, πNN coupling constant, [gπNN(0)]2/4π = 14.3. It is shown that vector mesons make significant contributions to the coupling constants gKNΛ and gKNΣ. Our values are existing within the experimental limits compared to the phenomenological values extracted from the kaon photo production experiments.

  13. Determination of magneto-optical constant of Fe films with weak measurements

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

    Qiu, Xiaodong; Hu, Dejiao; Du, Jinglei

    2014-09-29

    In this letter, a detecting method for the magneto-optical constant is presented by using weak measurements. The photonic spin Hall effect (PSHE), which manifests itself as spin-dependent splitting, is introduced to characterize the magneto-optical constant, and a propagation model to describe the quantitative relation between the magneto-optical constant and the PSHE is established. According to the amplified shift of the PSHE detected by weak measurements, we determinate the magneto-optical constant of the Fe film sample. The Kerr rotation is measured via the standard polarimetry method to verify the rationality and feasibility of our method. These findings may provide possible applicationsmore » in magnetic physics research.« less

  14. Detection and Mapping of the September 2017 Mexico Earthquakes Using DAS Fiber-Optic Infrastructure Arrays

    NASA Astrophysics Data System (ADS)

    Karrenbach, M. H.; Cole, S.; Williams, J. J.; Biondi, B. C.; McMurtry, T.; Martin, E. R.; Yuan, S.

    2017-12-01

    Fiber-optic distributed acoustic sensing (DAS) uses conventional telecom fibers for a wide variety of monitoring purposes. Fiber-optic arrays can be located along pipelines for leak detection; along borders and perimeters to detect and locate intruders, or along railways and roadways to monitor traffic and identify and manage incidents. DAS can also be used to monitor oil and gas reservoirs and to detect earthquakes. Because thousands of such arrays are deployed worldwide and acquiring data continuously, they can be a valuable source of data for earthquake detection and location, and could potentially provide important information to earthquake early-warning systems. In this presentation, we show that DAS arrays in Mexico and the United States detected the M8.1 and M7.2 Mexico earthquakes in September 2017. At Stanford University, we have deployed a 2.4 km fiber-optic DAS array in a figure-eight pattern, with 600 channels spaced 4 meters apart. Data have been recorded continuously since September 2016. Over 800 earthquakes from across California have been detected and catalogued. Distant teleseismic events have also been recorded, including the two Mexican earthquakes. In Mexico, fiber-optic arrays attached to pipelines also detected these two events. Because of the length of these arrays and their proximity to the event locations, we can not only detect the earthquakes but also make location estimates, potentially in near real time. In this presentation, we review the data recorded for these two events recorded at Stanford and in Mexico. We compare the waveforms recorded by the DAS arrays to those recorded by traditional earthquake sensor networks. Using the wide coverage provided by the pipeline arrays, we estimate the event locations. Such fiber-optic DAS networks can potentially play a role in earthquake early-warning systems, allowing actions to be taken to minimize the impact of an earthquake on critical infrastructure components. While many such fiber

  15. A two force-constant model for complexes B⋯M-X (B is a Lewis base and MX is any diatomic molecule): Intermolecular stretching force constants from centrifugal distortion constants D(J) or Δ(J).

    PubMed

    Bittner, Dror M; Walker, Nicholas R; Legon, Anthony C

    2016-02-21

    A two force-constant model is proposed for complexes of the type B⋯MX, in which B is a simple Lewis base of at least C2v symmetry and MX is any diatomic molecule lying along a Cn axis (n ≥ 2) of B. The model assumes a rigid subunit B and that force constants beyond quadratic are negligible. It leads to expressions that allow, in principle, the determination of three quadratic force constants F11, F12, and F22 associated with the r(B⋯M) = r2 and r(M-X) = r1 internal coordinates from the equilibrium centrifugal distortion constants DJ (e) or ΔJ (e), the equilibrium principal axis coordinates a1 and a2, and equilibrium principal moments of inertia. The model can be applied generally to complexes containing different types of intermolecular bond. For example, the intermolecular bond of B⋯MX can be a hydrogen bond if MX is a hydrogen halide, a halogen-bond if MX is a dihalogen molecule, or a stronger, coinage-metal bond if MX is a coinage metal halide. The equations were tested for BrCN, for which accurate equilibrium spectroscopic constants and a complete force field are available. In practice, equilibrium values of DJ (e) or ΔJ (e) for B⋯MX are not available and zero-point quantities must be used instead. The effect of doing so has been tested for BrCN. The zero-point centrifugal distortion constants DJ (0) or ΔJ (0) for all B⋯MX investigated so far are of insufficient accuracy to allow F11 and F22 to be determined simultaneously, even under the assumption F12 = 0 which is shown to be reasonable for BrCN. The calculation of F22 at a series of fixed values of F11 reveals, however, that in cases for which F11 is sufficiently larger than F22, a good approximation to F22 is obtained. Plots of F22 versus F11 have been provided for Kr⋯CuCl, Xe⋯CuCl, OC⋯CuCl, and C2H2⋯AgCl as examples. Even in cases where F22 ∼ F11 (e.g., OC⋯CuCl), such plots will yield either F22 or F11 if the other becomes available.

  16. A two force-constant model for complexes B⋯M-X (B is a Lewis base and MX is any diatomic molecule): Intermolecular stretching force constants from centrifugal distortion constants DJ or ΔJ

    NASA Astrophysics Data System (ADS)

    Bittner, Dror M.; Walker, Nicholas R.; Legon, Anthony C.

    2016-02-01

    A two force-constant model is proposed for complexes of the type B⋯MX, in which B is a simple Lewis base of at least C2v symmetry and MX is any diatomic molecule lying along a Cn axis (n ≥ 2) of B. The model assumes a rigid subunit B and that force constants beyond quadratic are negligible. It leads to expressions that allow, in principle, the determination of three quadratic force constants F11, F12, and F22 associated with the r(B⋯M) = r2 and r(M-X) = r1 internal coordinates from the equilibrium centrifugal distortion constants DJ e or ΔJ e , the equilibrium principal axis coordinates a1 and a2, and equilibrium principal moments of inertia. The model can be applied generally to complexes containing different types of intermolecular bond. For example, the intermolecular bond of B⋯MX can be a hydrogen bond if MX is a hydrogen halide, a halogen-bond if MX is a dihalogen molecule, or a stronger, coinage-metal bond if MX is a coinage metal halide. The equations were tested for BrCN, for which accurate equilibrium spectroscopic constants and a complete force field are available. In practice, equilibrium values of DJ e or ΔJ e for B⋯MX are not available and zero-point quantities must be used instead. The effect of doing so has been tested for BrCN. The zero-point centrifugal distortion constants DJ 0 or ΔJ 0 for all B⋯MX investigated so far are of insufficient accuracy to allow F11 and F22 to be determined simultaneously, even under the assumption F12 = 0 which is shown to be reasonable for BrCN. The calculation of F22 at a series of fixed values of F11 reveals, however, that in cases for which F11 is sufficiently larger than F22, a good approximation to F22 is obtained. Plots of F22 versus F11 have been provided for Kr⋯CuCl, Xe⋯CuCl, OC⋯CuCl, and C2H2⋯AgCl as examples. Even in cases where F22 ˜ F11 (e.g., OC⋯CuCl), such plots will yield either F22 or F11 if the other becomes available.

  17. Garlic extract diallyl sulfide (DAS) activates nuclear receptor CAR to induce the Sult1e1 gene in mouse liver.

    PubMed

    Sueyoshi, Tatsuya; Green, William D; Vinal, Kellie; Woodrum, Tyler S; Moore, Rick; Negishi, Masahiko

    2011-01-01

    Constituent chemicals in garlic extract are known to induce phase I and phase II enzymes in rodent livers. Here we have utilized Car(+/+) and Car(-/-) mice to demonstrate that the nuclear xenobiotic receptor CAR regulated the induction of the estrogen sulfotransferase Sult1e1 gene by diallyl sulfide (DAS) treatment in mouse liver. DAS treatment caused CAR accumulation in the nucleus, resulting in a remarkable increase of SULT1E1 mRNA (3,200 fold) and protein in the livers of Car(+/+) females but not of Car(-/-) female mice. DAS also induced other CAR-regulated genes such as Cyp2b10, Cyp3a11 and Gadd45β. Compared with the rapid increase of these mRNA levels, which began as early as 6 hours after DAS treatment, the levels of SULT1E1 mRNA began increasing after 24 hours. This slow response to DAS suggested that CAR required an additional factor to activate the Sult1e1 gene or that this activation was indirect. Despite the remarkable induction of SULT1E1, there was no decrease in the serum levels of endogenous E2 or increase of estrone sulfate while the clearance of exogenously administrated E2 was accelerated in DAS treated mice.

  18. (Re)locating (I)dentity With(in) Politicized (Re)presentation of Fe/Male Body in Kamala Das' Poetry

    ERIC Educational Resources Information Center

    Sultana, Sharmin; Sarwar, Nadia

    2016-01-01

    This paper is going to argue that the selected poems of renowned Indian poet Kamala Das are inclined to relocate both feminine and masculine identity through the politicized representation of body. Kamala Das' representation of body in her poems has always been viewed as a medium of re-historicizing the pain, sufferings, and psychological trauma…

  19. The Deaf Acculturation Scale (DAS): Development and Validation of a 58-Item Measure

    PubMed Central

    Maxwell-McCaw, Deborah; Zea, Maria Cecilia

    2011-01-01

    This study involved the development and validation of the Deaf Acculturation Scale (DAS), a new measure of cultural identity for Deaf and hard-of-hearing (hh) populations. Data for this study were collected online and involved a nation-wide sample of 3,070 deaf/hh individuals. Results indicated strong internal reliabilities for all the subscales, and construct validity was established by demonstrating that the DAS could discriminate groups based on parental hearing status, school background, and use of self-labels. Construct validity was further demonstrated through factorial analyses, and findings resulted in a final 58-item measure. Directions for future research are discussed. PMID:21263041

  20. Determination of mass density, dielectric, elastic, and piezoelectric constants of bulk GaN crystal.

    PubMed

    Soluch, Waldemar; Brzozowski, Ernest; Lysakowska, Magdalena; Sadura, Jolanta

    2011-11-01

    Mass density, dielectric, elastic, and piezoelectric constants of bulk GaN crystal were determined. Mass density was obtained from the measured ratio of mass to volume of a cuboid. The dielectric constants were determined from the measured capacitances of an interdigital transducer (IDT) deposited on a Z-cut plate and from a parallel plate capacitor fabricated from this plate. The elastic and piezoelectric constants were determined by comparing the measured and calculated SAW velocities and electromechanical coupling coefficients on the Z- and X-cut plates. The following new constants were obtained: mass density p = 5986 kg/m(3); relative dielectric constants (at constant strain S) ε(S)(11)/ε(0) = 8.6 and ε(S)(11)/ε(0) = 10.5, where ε(0) is a dielectric constant of free space; elastic constants (at constant electric field E) C(E)(11) = 349.7, C(E)(12) = 128.1, C(E)(13) = 129.4, C(E)(33) = 430.3, and C(E)(44) = 96.5 GPa; and piezoelectric constants e(33) = 0.84, e(31) = -0.47, and e(15) = -0.41 C/m(2).

  1. Simulating Supercapacitors: Can We Model Electrodes As Constant Charge Surfaces?

    PubMed

    Merlet, Céline; Péan, Clarisse; Rotenberg, Benjamin; Madden, Paul A; Simon, Patrice; Salanne, Mathieu

    2013-01-17

    Supercapacitors based on an ionic liquid electrolyte and graphite or nanoporous carbon electrodes are simulated using molecular dynamics. We compare a simplified electrode model in which a constant, uniform charge is assigned to each carbon atom with a realistic model in which a constant potential is applied between the electrodes (the carbon charges are allowed to fluctuate). We show that the simulations performed with the simplified model do not provide a correct description of the properties of the system. First, the structure of the adsorbed electrolyte is partly modified. Second, dramatic differences are observed for the dynamics of the system during transient regimes. In particular, upon application of a constant applied potential difference, the increase in the temperature, due to the Joule effect, associated with the creation of an electric current across the cell follows Ohm's law, while unphysically high temperatures are rapidly observed when constant charges are assigned to each carbon atom.

  2. Statistical Quality Control of Moisture Data in GEOS DAS

    NASA Technical Reports Server (NTRS)

    Dee, D. P.; Rukhovets, L.; Todling, R.

    1999-01-01

    A new statistical quality control algorithm was recently implemented in the Goddard Earth Observing System Data Assimilation System (GEOS DAS). The final step in the algorithm consists of an adaptive buddy check that either accepts or rejects outlier observations based on a local statistical analysis of nearby data. A basic assumption in any such test is that the observed field is spatially coherent, in the sense that nearby data can be expected to confirm each other. However, the buddy check resulted in excessive rejection of moisture data, especially during the Northern Hemisphere summer. The analysis moisture variable in GEOS DAS is water vapor mixing ratio. Observational evidence shows that the distribution of mixing ratio errors is far from normal. Furthermore, spatial correlations among mixing ratio errors are highly anisotropic and difficult to identify. Both factors contribute to the poor performance of the statistical quality control algorithm. To alleviate the problem, we applied the buddy check to relative humidity data instead. This variable explicitly depends on temperature and therefore exhibits a much greater spatial coherence. As a result, reject rates of moisture data are much more reasonable and homogeneous in time and space.

  3. Expiratory Time Constant and Sleep Apnea Severity in the Overlap Syndrome.

    PubMed

    Wiriyaporn, Darunee; Wang, Lu; Aboussouan, Loutfi S

    2016-03-01

    Lung mechanics in the overlap of COPD and sleep apnea impact the severity of sleep apnea. Specifically, increased lung compliance with hyperinflation protects against sleep apnea, whereas increased airway resistance worsens sleep apnea. We sought to assess whether the expiratory time constant, which reflects lung mechanics, is associated with sleep apnea severity in such patients. Polysomnographies in 34 subjects with the overlap syndrome were reviewed. Three time constants were measured for each of up to 5 stages (wake, NREM stages, and REM). The time constants were derived by fitting time and pressure coordinates on the expiratory portion of a nasal pressure signal along an exponentially decaying equation, and solving for the time constant. Demographics, morphometrics, wake end-tidal CO2, right diaphragmatic arc on a chest radiograph, and the apnea-hypopnea index (AHI) were recorded. The time constant was not associated with age, gender, body mass index, right diaphragmatic arc, or wake end-tidal CO2, and was not significantly different between sleep stages. A mean time constant (TC) was therefore obtained. Subjects with a TC > 0.5 seconds had a greater AHI than those with a TC ≤ 0.5 seconds (median AHI 58 vs. 18, respectively, p = 0.003; Odds ratio of severe sleep apnea 10.6, 95% CI 3.9-51.1, p = 0.005). A larger time constant in the overlap syndrome is associated with increased odds of severe sleep apnea, suggesting a greater importance of airway resistance relative to lung compliance in sleep apnea causation in these subjects. © 2016 American Academy of Sleep Medicine.

  4. The vibrational dependence of dissociative recombination: Rate constants for N{sub 2}{sup +}

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

    Guberman, Steven L., E-mail: slg@sci.org

    Dissociative recombination rate constants are reported with electron temperature dependent uncertainties for the lowest 5 vibrational levels of the N{sub 2}{sup +} ground state. The rate constants are determined from ab initio calculations of potential curves, electronic widths, quantum defects, and cross sections. At 100 K electron temperature, the rate constants overlap with the exception of the third vibrational level. At and above 300 K, the rate constants for excited vibrational levels are significantly smaller than that for the ground level. It is shown that any experimentally determined total rate constant at 300 K electron temperature that is smaller thanmore » 2.0 × 10{sup −7} cm{sup 3}/s is likely to be for ions that have a substantially excited vibrational population. Using the vibrational level specific rate constants, the total rate constant is in very good agreement with that for an excited vibrational distribution found in a storage ring experiment. It is also shown that a prior analysis of a laser induced fluorescence experiment is quantitatively flawed due to the need to account for reactions with unknown rate constants. Two prior calculations of the dissociative recombination rate constant are shown to be inconsistent with the cross sections upon which they are based. The rate constants calculated here contribute to the resolution of a 30 year old disagreement between modeled and observed N{sub 2}{sup +} ionospheric densities.« less

  5. Clinical Course of Homozygous Hemoglobin Constant Spring in Pediatric Patients.

    PubMed

    Komvilaisak, Patcharee; Jetsrisuparb, Arunee; Fucharoen, Goonnapa; Komwilaisak, Ratana; Jirapradittha, Junya; Kiatchoosakun, Pakaphan

    2018-04-17

    Hemoglobin (Hb) Constant Spring is an alpha-globin gene variant due to a mutation of the stop codon resulting in the elongation of the encoded polypeptide from 141 to 172 amino acid residues. Patients with homozygous Hb Constant Spring are usually mildly anemic. We retrospectively describe clinical manifestations, diagnosis, laboratory investigations, treatment, and associated findings in pediatric patients with homozygous Hb Constant Spring followed-up at Srinagarind Hospital. Sixteen pediatric cases (5 males and 11 females) were diagnosed in utero (N=6) or postnatal (n=10). Eleven cases were diagnosed with homozygous Hb Constant Spring, 4 with homozygous Hb Constant Spring with heterozygous Hb E, and 1 with homozygous Hb Constant Spring with homozygous Hb E. Three cases were delivered preterm. Six patients had low birth weights. Clinical manifestations included fetal anemia in 6 cases, hepatomegaly in 1 case, hepatosplenomegaly in 2 cases, splenomegaly in 1 case. Twelve cases exhibited early neonatal jaundice, 9 of which required phototherapy. Six cases received red cell transfusions; 1 (3), >1 (3). After the first few months of life, almost all patients had mild microcytic hypochromic anemia and an increased reticulocyte count with a wide red cell distribution (RDW), but no longer required red cell transfusion. At 1 to 2 years of age, some patients still had mild microcytic hypochromic anemia and some had normocytic hypochromic anemia with Hb around 10 g/dL, increased reticulocyte count and wide RDW. Associated findings included hypothyroidism (2), congenital heart diseases (4), genitourinary abnormalities (3), gastrointestinal abnormalities (2), and developmental delay (1). Pediatric patients with homozygous Hb Constant Spring developed severe anemia in utero and up to the age of 2 to 3 months postnatal, requiring blood transfusions. Subsequently, their anemia was mild with no evidence of hepatosplenomegaly. Their Hb level was above 9 g/dL with hypochromic

  6. 21 CFR 1250.85 - Drinking fountains and coolers; ice; constant temperature bottles.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Drinking fountains and coolers; ice; constant... Drinking fountains and coolers; ice; constant temperature bottles. (a) Drinking fountains and coolers shall... prevent backflow. (b) Ice shall not be permitted to come in contact with water in coolers or constant...

  7. 21 CFR 1250.85 - Drinking fountains and coolers; ice; constant temperature bottles.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Drinking fountains and coolers; ice; constant... Drinking fountains and coolers; ice; constant temperature bottles. (a) Drinking fountains and coolers shall... prevent backflow. (b) Ice shall not be permitted to come in contact with water in coolers or constant...

  8. 21 CFR 1250.85 - Drinking fountains and coolers; ice; constant temperature bottles.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Drinking fountains and coolers; ice; constant... Drinking fountains and coolers; ice; constant temperature bottles. (a) Drinking fountains and coolers shall... prevent backflow. (b) Ice shall not be permitted to come in contact with water in coolers or constant...

  9. 21 CFR 1250.85 - Drinking fountains and coolers; ice; constant temperature bottles.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Drinking fountains and coolers; ice; constant... Drinking fountains and coolers; ice; constant temperature bottles. (a) Drinking fountains and coolers shall... prevent backflow. (b) Ice shall not be permitted to come in contact with water in coolers or constant...

  10. 21 CFR 1250.85 - Drinking fountains and coolers; ice; constant temperature bottles.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Drinking fountains and coolers; ice; constant... Drinking fountains and coolers; ice; constant temperature bottles. (a) Drinking fountains and coolers shall... prevent backflow. (b) Ice shall not be permitted to come in contact with water in coolers or constant...

  11. Determination of stability constants of aminoglycoside antibiotics with their metal complexes

    NASA Astrophysics Data System (ADS)

    Tiwow, Vanny M. A.

    2014-03-01

    One group of aminoglycoside antibiotics contains aminosugars. The aminosugar neomycin B with its derivate product neamine (2-Deoxy-4-0-(2,6-diamino-2,6-dideoxy-α-D-glucopyranosyl)-D-Streptamine) was identified as a free ligands and metal complexes. In particular, the stability constants of metal complexes by potentiometric titration techniques were investigated. Our previous study had determined the acid dissociation constants of these aminosugars with few metal complexes in fair depth. In this work, the complexation of two pyridine-containing amino alcohols and an amino sugar (neamine) have been measured potentiometrically. For instance, the stability constant of copper(II) complexation were determine and the model system generated an excellent fit. Stability constants with several metals have been determined and will be reported.

  12. Paramecia Swim with a constant propulsion in Solutions of Varying Viscosity

    NASA Astrophysics Data System (ADS)

    Valles, James M., Jr.; Jung, Ilyong; Mickalide, Harry; Park, Hojin; Powers, Thomas

    2012-02-01

    Paramecia swim through the coordinated beating of the 1000's of cilia covering their body. We have measured the swimming speed of populations of Paramecium Caudatam in solutions of different viscosity, η, to see how their propulsion changes with increased drag. We have found the average instantaneous speed, V to decrease monotonically with increasing η. The product ηv is roughly constant over a factor of 7 change in viscosity suggesting that paramecia swim at constant propulsion force. The distribution of swimming speeds is Gaussian. The width appears proportional to the average speed implying that both fast and slow swimmers exert a constant propulsion. We discuss the possibility that this behavior implies that the body cilia beat at constant force with varying viscosity.

  13. Constant mortality and fertility over age in Hydra

    PubMed Central

    Schaible, Ralf; Scheuerlein, Alexander; Dańko, Maciej J.; Gampe, Jutta; Martínez, Daniel E.; Vaupel, James W.

    2015-01-01

    Senescence, the increase in mortality and decline in fertility with age after maturity, was thought to be inevitable for all multicellular species capable of repeated breeding. Recent theoretical advances and compilations of data suggest that mortality and fertility trajectories can go up or down, or remain constant with age, but the data are scanty and problematic. Here, we present compelling evidence for constant age-specific death and reproduction rates in Hydra, a basal metazoan, in a set of experiments comprising more than 3.9 million days of observations of individual Hydra. Our data show that 2,256 Hydra from two closely related species in two laboratories in 12 cohorts, with cohort age ranging from 0 to more than 41 y, have extremely low, constant rates of mortality. Fertility rates for Hydra did not systematically decline with advancing age. This falsifies the universality of the theories of the evolution of aging that posit that all species deteriorate with age after maturity. The nonsenescent life history of Hydra implies levels of maintenance and repair that are sufficient to prevent the accumulation of damage for at least decades after maturity, far longer than the short life expectancy of Hydra in the wild. A high proportion of stem cells, constant and rapid cell turnover, few cell types, a simple body plan, and the fact that the germ line is not segregated from the soma are characteristics of Hydra that may make nonsenescence feasible. Nonsenescence may be optimal because lifetime reproduction may be enhanced more by extending adult life spans than by increasing daily fertility. PMID:26644561

  14. Constant mortality and fertility over age in Hydra.

    PubMed

    Schaible, Ralf; Scheuerlein, Alexander; Dańko, Maciej J; Gampe, Jutta; Martínez, Daniel E; Vaupel, James W

    2015-12-22

    Senescence, the increase in mortality and decline in fertility with age after maturity, was thought to be inevitable for all multicellular species capable of repeated breeding. Recent theoretical advances and compilations of data suggest that mortality and fertility trajectories can go up or down, or remain constant with age, but the data are scanty and problematic. Here, we present compelling evidence for constant age-specific death and reproduction rates in Hydra, a basal metazoan, in a set of experiments comprising more than 3.9 million days of observations of individual Hydra. Our data show that 2,256 Hydra from two closely related species in two laboratories in 12 cohorts, with cohort age ranging from 0 to more than 41 y, have extremely low, constant rates of mortality. Fertility rates for Hydra did not systematically decline with advancing age. This falsifies the universality of the theories of the evolution of aging that posit that all species deteriorate with age after maturity. The nonsenescent life history of Hydra implies levels of maintenance and repair that are sufficient to prevent the accumulation of damage for at least decades after maturity, far longer than the short life expectancy of Hydra in the wild. A high proportion of stem cells, constant and rapid cell turnover, few cell types, a simple body plan, and the fact that the germ line is not segregated from the soma are characteristics of Hydra that may make nonsenescence feasible. Nonsenescence may be optimal because lifetime reproduction may be enhanced more by extending adult life spans than by increasing daily fertility.

  15. Novas determinações dos parâmetros atmosféricos das estrelas anãs brancas DA

    NASA Astrophysics Data System (ADS)

    Giovannini, O.; Costa, A. F. M.; Kepler, S. O.

    2003-08-01

    Nós temos selecionado uma amostra de estrelas anãs brancas DA (atmosfera de hidrogênio) a partir dos índices de Strömgren cujos valores estão próximos a região de instabilidade das estrelas anãs brancas DA variáveis, as chamadas estrelas DAV ou ZZ Ceti. O objetivo é determinar os parâmetros fundamentais (temperatura efetiva, Teff, aceleração da gravidade, log g, e massa) destas estrelas para verificar quais os parâmetros estelares estão envolvidos com o mecanismo de pulsação das estrelas DAV. Nós obtemos, até agora, mais de 120 espectros óticos de estrelas DA. Entre as estrelas selecionadas há 20 estrelas variáveis (DAV). Assim, podemos verificar se existem ou não estrelas não variáveis dentro da faixa de instabilidade das estrelas ZZ Ceti. Neste trabalho nós apresentamos a determinação dos parâmetros atmosféricos (temperatura efetiva, Teff, e aceleração da gravidade, log g) das estrelas anãs brancas DA usando os novos modelos de atmosfera ML2/a = 0.6. Estes modelos têm sido utilizados recentemente por fornecerem uma excelente consistência interna na determinação das temperaturas nas regiões do ultra-violeta e ótico. Os parâmetros atmosféricos são determinados espectroscopicamente através da comparação do fluxo de energia das linhas de Balmer (Hb à H9) entre os espectros observados e sintéticos (gerados pelos modelos de atmosfera). As temperaturas obtidas com os novos modelos são, em geral, menores (~ 1000 K menos) que as temperaturas determinadas anteriormente, com modelos ML1. Os valores de log g não mudaram significativamente (menos de 10%). A faixa de instabilidade das DAVs está entre 11000 e 13000 K, consistente com dados de outros autores.

  16. Solution Strategies for Constant Acceleration Problems

    ERIC Educational Resources Information Center

    Wheaton, S. M.; Binder, P.-M.

    2017-01-01

    We discuss strategies for the general solution of single-step 1D constant acceleration problems. In a slightly restricted form, these problems have five variables (?"x," "v[subscript 0]," "v," "a" and "t") and two independent equations, so three variables must be given to solve for the other two,…

  17. Dielectric constants of soils at microwave frequencies-2

    NASA Technical Reports Server (NTRS)

    Wang, J.; Schmugge, T.; Williams, D.

    1978-01-01

    The dielectric constants of several soil samples were measured at frequencies of 5 and 19 GHz using the infinite transmission line method. The results of these measurements are presented and discussed with respect to soil types and texture structures. A comparison is made with other measurements at 1.4 GHz. At all three frequencies, the dependence of dielectric constant on soil moisture can be approximated by two straight lines. At low moisture, the slope is less than at high moisture level. The intersection of the two lines is believed to be a function of soil texture.

  18. Newman-Penrose constants of the Kerr-Newman metric

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

    Gong Xuefei; Shang Yu; Bai Shan

    The Newman-Unti formalism of the Kerr-Newman metric near future null infinity is developed, with which the Newman-Penrose constants for both the gravitational and electromagnetic fields of the Kerr-Newman metric are computed and shown to be zero. The multipole structure near future null infinity in the sense of Janis-Newman of the Kerr-Newman metric is then further studied. It is found that up to the 2{sup 4}-pole, modulo a constant dependent upon the order of the pole, these multipole moments agree with those of Geroch-Hansen multipole moments defined at spatial infinity.

  19. Imaging performance of an isotropic negative dielectric constant slab.

    PubMed

    Shivanand; Liu, Huikan; Webb, Kevin J

    2008-11-01

    The influence of material and thickness on the subwavelength imaging performance of a negative dielectric constant slab is studied. Resonance in the plane-wave transfer function produces a high spatial frequency ripple that could be useful in fabricating periodic structures. A cost function based on the plane-wave transfer function provides a useful metric to evaluate the planar slab lens performance, and using this, the optimal slab dielectric constant can be determined.

  20. Distributed Acoustic Sensing (DAS) Array near a Highway for Traffic Monitoring and Near-Surface Shear-Wave Velocity Profiles

    NASA Astrophysics Data System (ADS)

    Wang, H. F.; Fratta, D.; Lancelle, C.; Ak, E. Ms; Lord, N. E.

    2017-12-01

    Monitoring traffic is important for many technical reasons. It allows for better design of future roads and assessment of the state of current roads. The number, size, weight, and speed of vehicles control deterioration rate. Also, real-time information supplies data to intelligent information systems to help control traffic. Recently there have been studies looking at monitoring traffic seismically as vibrations from traffic are not sensitive to weather and poor visibility. Furthermore, traffic noise can be used to image S-wave velocity distribution in the near surface by capturing and interpreting Rayleigh and Love waves (Nakata, 2016; Zeng et al. 2016). The capability of DAS for high spatial sampling (1 m), temporal sampling (up to 10 kHz), and distributed nature (tens of kilometers) allows for a closer look at the traffic as it passes and how the speed of the vehicle may change over the length of the array. The potential and difficulties of using DAS for these objectives were studied using two DAS arrays. One at Garner Valley in Southern California (a 700-meter array adjacent to CA Highway 74) and another in Brady Hot Springs, Nevada (an 8700-meter array adjacent to Interstate 80). These studies experimentally evaluated the use of DAS data for monitoring traffic and assessing the use of traffic vibration as non-localized sources for seismic imaging. DAS arrays should also be resilient to issues with lighting conditions that are problematic for video monitoring and it may be sensitive to the weight of a vehicle. This study along a major interstate provides a basis for examining DAS' potential and limitations as a key component of intelligent highway systems.

  1. Teaching Nanochemistry: Madelung Constants of Nanocrystals

    ERIC Educational Resources Information Center

    Baker, Mark D.; Baker, A. David

    2010-01-01

    The Madelung constants for binary ionic nanoparticles are determined. The computational method described here sums the Coulombic interactions of each ion in the particle without the use of partial charges commonly used for bulk materials. The results show size-dependent lattice energies. This is a useful concept in teaching how properties such as…

  2. Unruh thermal hadronization and the cosmological constant

    NASA Astrophysics Data System (ADS)

    Frassino, Antonia M.; Bleicher, Marcus; Mann, Robert B.

    2018-05-01

    We use black holes with a negative cosmological constant to investigate aspects of the freeze-out temperature for hadron production in high energy heavy-ion collisions. The two black hole solutions present in the anti-de Sitter geometry have different mass and are compared to the data showing that the small black hole solution is in good agreement. This is a new feature in the literature since the small black hole in general relativity has different thermodynamic behavior from that of the large black hole solution. We find that the inclusion of the cosmological constant (which can be interpreted as the plasma pressure) leads to a lowering of the temperature of the freeze-out curve as a function of the baryochemical potential, improving the description previously suggested by Castorina, Kharzeev, and Satz.

  3. A review and empirical study of the composite scales of the Das-Naglieri cognitive assessment system.

    PubMed

    McCrea, Simon M

    2009-01-01

    Alexander Luria's model of the working brain consisting of three functional units was formulated through the examination of hundreds of focal brain-injury patients. Several psychometric instruments based on Luria's syndrome analysis and accompanying qualitative tasks have been developed since the 1970s. In the mid-1970s, JP Das and colleagues defined a specific cognitive processes model based directly on Luria's two coding units termed simultaneous and successive by studying diverse cross-cultural, ability, and socioeconomic strata. The cognitive assessment system is based on the PASS model of cognitive processes and consists of four composite scales of Planning-Attention-Simultaneous-Successive (PASS) devised by Naglieri and Das in 1997. Das and colleagues developed the two new scales of planning and attention to more closely model Luria's theory of higher cortical functions. In this paper a theoretical review of Luria's theory, Das and colleagues elaboration of Luria's model, and the neural correlates of PASS composite scales based on extant studies is summarized. A brief empirical study of the neuropsychological specificity of the PASS composite scales in a sample of 33 focal cortical stroke patients using cluster analysis is then discussed. Planning and simultaneous were sensitive to right hemisphere lesions. These findings were integrated with recent functional neuroimaging studies of PASS scales. In sum it was found that simultaneous is strongly dependent on dual bilateral occipitoparietal interhemispheric coordination whereas successive demonstrated left frontotemporal specificity with some evidence of interhemispheric coordination across the prefrontal cortex. Hence, support for the validity of the PASS composite scales was found as well as for the axiom of the independence of code content from code type originally specified in 1994 by Das, Naglieri, and Kirby.

  4. A New Contribution for WYP 2005: The Golden Ratio, Bohr Radius, Planck's Constant, Fine-Structure Constant and g-Factors

    NASA Astrophysics Data System (ADS)

    Heyrovska, R.; Narayan, S.

    2005-10-01

    Recently, the ground state Bohr radius (aB) of hydrogen was shown to be divided into two Golden sections, aB,p = aB/ø2 and aB,e = aB/ø at the point of electrical neutrality, where ø = 1.618 is the Golden ratio (R. Heyrovska, Molecular Physics 103: 877-882, and the literature cited therein). The origin of the difference of two energy terms in the Rydberg equation was thus shown to be in the ground state energy itself, as shown below: EH = (1/2)e2/(κaB) = (1/2)(e2/κ) [(1/aB,p - (1/aB,e)] (1). This work brings some new results that 1) a unit charge in vacuum has a magnetic moment, 2) (e2/2κ) in eq. (1) is an electromagnetic condenser constant, 3) the de Broglie wavelengths of the proton and electron correspond to the Golden arcs of a circle with the Bohr radius, 4) the fine structure constant (α) is the ratio of the Planck's constants without and with the interaction of light with matter, 5) the g-factors of the electron and proton, ge/2 and gp/2 divide the Bohr radius at the magnetic center and 6) the ``mysterious'' value (137.036) of α -1 = (360/ø2) - (2/ø3), where (2/ø3) arises from the difference, (gp - ge).

  5. Garlic Extract Diallyl Sulfide (DAS) Activates Nuclear Receptor CAR to Induce the Sult1e1 Gene in Mouse Liver

    PubMed Central

    Sueyoshi, Tatsuya; Green, William D.; Vinal, Kellie; Woodrum, Tyler S.; Moore, Rick; Negishi, Masahiko

    2011-01-01

    Constituent chemicals in garlic extract are known to induce phase I and phase II enzymes in rodent livers. Here we have utilized Car +/+ and Car −/− mice to demonstrate that the nuclear xenobiotic receptor CAR regulated the induction of the estrogen sulfotransferase Sult1e1 gene by diallyl sulfide (DAS) treatment in mouse liver. DAS treatment caused CAR accumulation in the nucleus, resulting in a remarkable increase of SULT1E1 mRNA (3,200 fold) and protein in the livers of Car +/+ females but not of Car −/− female mice. DAS also induced other CAR-regulated genes such as Cyp2b10, Cyp3a11 and Gadd45β. Compared with the rapid increase of these mRNA levels, which began as early as 6 hourrs after DAS treatment, the levels of SULT1E1 mRNA began increasing after 24 hours. This slow response to DAS suggested that CAR required an additional factor to activate the Sult1e1 gene or that this activation was indirect. Despite the remarkable induction of SULT1E1, there was no decrease in the serum levels of endogenous E2 or increase of estrone sulfate while the clearance of exogenously administrated E2 was accelerated in DAS treated mice. PMID:21698271

  6. [Grades evaluation of Scutellariae Radix slices based on quality constant].

    PubMed

    Deng, Zhe; Zhang, Jun; Jiao, Meng-Jiao; Zhong, Wen; Cui, Wen-Jin; Cheng, Jin-Tang; Chen, Sha; Wang, Yue-Sheng; Liu, An

    2017-05-01

    By measuring the morphological indexes and the marker components content of 22 batches of Scutellariae Radix slices as well as calculating the quality constant, this research was aimed to establish a new method of evaluating the specifications and grades of Scutellariae Radix slices. The quality constants of these samples were in the range of 0.04-0.49, which can be divided into several grades based on the real requirement. If they were divided into three grades, the quality constant was ≥0.39 for the first grade, <0.39 but ≥0.24 for the second grade, and <0.24 for the third grade. This work indicated that the quality constants characterizing both apparent parameters and intrinsic quality can be used as a comprehensive evaluation index to classify the grades of traditional Chinese medicine quantitatively, clearly and objectively. The research results in this paper would provide new ideas and references for evaluating the specifications and grades of traditional Chinese medicines. Copyright© by the Chinese Pharmaceutical Association.

  7. Constant-pH Molecular Dynamics Simulations for Large Biomolecular Systems

    DOE PAGES

    Radak, Brian K.; Chipot, Christophe; Suh, Donghyuk; ...

    2017-11-07

    We report that an increasingly important endeavor is to develop computational strategies that enable molecular dynamics (MD) simulations of biomolecular systems with spontaneous changes in protonation states under conditions of constant pH. The present work describes our efforts to implement the powerful constant-pH MD simulation method, based on a hybrid nonequilibrium MD/Monte Carlo (neMD/MC) technique within the highly scalable program NAMD. The constant-pH hybrid neMD/MC method has several appealing features; it samples the correct semigrand canonical ensemble rigorously, the computational cost increases linearly with the number of titratable sites, and it is applicable to explicit solvent simulations. The present implementationmore » of the constant-pH hybrid neMD/MC in NAMD is designed to handle a wide range of biomolecular systems with no constraints on the choice of force field. Furthermore, the sampling efficiency can be adaptively improved on-the-fly by adjusting algorithmic parameters during the simulation. Finally, illustrative examples emphasizing medium- and large-scale applications on next-generation supercomputing architectures are provided.« less

  8. Constant-pH Molecular Dynamics Simulations for Large Biomolecular Systems

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

    Radak, Brian K.; Chipot, Christophe; Suh, Donghyuk

    We report that an increasingly important endeavor is to develop computational strategies that enable molecular dynamics (MD) simulations of biomolecular systems with spontaneous changes in protonation states under conditions of constant pH. The present work describes our efforts to implement the powerful constant-pH MD simulation method, based on a hybrid nonequilibrium MD/Monte Carlo (neMD/MC) technique within the highly scalable program NAMD. The constant-pH hybrid neMD/MC method has several appealing features; it samples the correct semigrand canonical ensemble rigorously, the computational cost increases linearly with the number of titratable sites, and it is applicable to explicit solvent simulations. The present implementationmore » of the constant-pH hybrid neMD/MC in NAMD is designed to handle a wide range of biomolecular systems with no constraints on the choice of force field. Furthermore, the sampling efficiency can be adaptively improved on-the-fly by adjusting algorithmic parameters during the simulation. Finally, illustrative examples emphasizing medium- and large-scale applications on next-generation supercomputing architectures are provided.« less

  9. Frequency-constant Q, unity and disorder

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

    Hargreaves, N.D.

    1995-12-31

    In exploration geophysics we obtain information about the earth by observing its response to different types of applied force. The response can cover the full range of possible Q values (where Q, the quality factor, is a measure of energy dissipation), from close to infinity in the case of deep crustal seismic to close to 0 in the case of many electromagnetic methods. When Q is frequency-constant, however, the various types of response have a common scaling behavior and can be described as being self-affine. The wave-equation then takes on a generalised form, changing from the standard wave-equation at Qmore » = {infinity} to the diffusion equation at Q = 0, via lossy, diffusive, propagation at intermediate Q values. Solutions of this wave-diffusion equation at any particular Q value can be converted to an equivalent set of results for any other Q value. In particular it is possible to convert from diffusive to wave propagation by a mapping from Q < {infinity} to Q = {infinity}. In the context of seismic sounding this is equivalent to applying inverse Q-filtering; in a more general context the mapping integrates different geophysical observations by referencing them to the common result at Q = {infinity}. The self-affinity of the observations for frequency-constant Q is an expression of scale invariance in the fundamental physical properties of the medium of propagation, this being the case whether the mechanism of diffusive propagation is scattering of intrinsic attenuation. Scale invariance, or fractal scaling, is a general property of disordered systems; the assumption of frequency-constant Q not only implies a unity between different geophysical observations, but also suggests that it is the disordered nature of the earth`s sub-surface that is the unifying factor.« less

  10. A Constant-Force Resistive Exercise Unit

    NASA Technical Reports Server (NTRS)

    Colosky, Paul; Ruttley, Tara

    2010-01-01

    A constant-force resistive exercise unit (CFREU) has been invented for use in both normal gravitational and microgravitational environments. In comparison with a typical conventional exercise machine, this CFREU weighs less and is less bulky: Whereas weight plates and associated bulky supporting structures are used to generate resistive forces in typical conventional exercise machines, they are not used in this CFREU. Instead, resistive forces are generated in this CFREU by relatively compact, lightweight mechanisms based on constant-torque springs wound on drums. Each such mechanism is contained in a module, denoted a resistive pack, that includes a shaft for making a torque connection to a cable drum. During a stroke of resistive exercise, the cable is withdrawn from the cable drum against the torque exerted by the resistance pack. The CFREU includes a housing, within which can be mounted one or more resistive pack(s). The CFREU also includes mechanisms for engaging any combination of (1) one or more resistive pack(s) and (2) one or more spring(s) within each resistive pack to obtain a desired level of resistance.

  11. Change is a Constant.

    PubMed

    Lubowitz, James H; Provencher, Matthew T; Brand, Jefferson C; Rossi, Michael J; Poehling, Gary G

    2015-06-01

    In 2015, Henry P. Hackett, Managing Editor, Arthroscopy, retires, and Edward A. Goss, Executive Director, Arthroscopy Association of North America (AANA), retires. Association is a positive constant, in a time of change. With change comes a need for continuing education, research, and sharing of ideas. While the quality of education at AANA and ISAKOS is superior and most relevant, the unique reason to travel and meet is the opportunity to interact with innovative colleagues. Personal interaction best stimulates new ideas to improve patient care, research, and teaching. Through our network, we best create innovation. Copyright © 2015 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

  12. Determination of acidity constants of curcumin in aqueous solution and apparent rate constant of its decomposition

    NASA Astrophysics Data System (ADS)

    Bernabé-Pineda, Margarita; Ramírez-Silva, María. Teresa; Romero-Romo, Mario; González-Vergara, Enrique; Rojas-Hernández, Alberto

    2004-04-01

    The stability of curcumin (H 3Cur) in aqueous media is improved when the systems in which it is present are at high pH values (higher than 11.7), fitting a model describable by a pseudo-zero order with a rate constant k' for the disappearance of the Cur 3- species of 1.39 (10 -9) M min -1. There were three acidity constants measured for the curcumin as follows: p KA3=10.51±0.01 corresponding to the equilibrium HCur 2-=Cur 3-+H +, a p KA2=9.88±0.02 corresponding to the equilibrium H 2Cur -=HCur -2+H +. These p KA values were attributed to the hydrogen of the phenol part of the curcumin, while the p KA1=8.38±0.04 corresponds to the equilibrium H 3Cur=H 2Cur -+H + and is attributed the acetylacetone type group. Formation of quinoid structures play an important role in the tautomeric forms of the curcumin in aqueous media, which makes the experimental values differ from the theoretically calculated ones, depending on the conditions adopted in the study.

  13. Precisely and Accurately Inferring Single-Molecule Rate Constants

    PubMed Central

    Kinz-Thompson, Colin D.; Bailey, Nevette A.; Gonzalez, Ruben L.

    2017-01-01

    The kinetics of biomolecular systems can be quantified by calculating the stochastic rate constants that govern the biomolecular state versus time trajectories (i.e., state trajectories) of individual biomolecules. To do so, the experimental signal versus time trajectories (i.e., signal trajectories) obtained from observing individual biomolecules are often idealized to generate state trajectories by methods such as thresholding or hidden Markov modeling. Here, we discuss approaches for idealizing signal trajectories and calculating stochastic rate constants from the resulting state trajectories. Importantly, we provide an analysis of how the finite length of signal trajectories restrict the precision of these approaches, and demonstrate how Bayesian inference-based versions of these approaches allow rigorous determination of this precision. Similarly, we provide an analysis of how the finite lengths and limited time resolutions of signal trajectories restrict the accuracy of these approaches, and describe methods that, by accounting for the effects of the finite length and limited time resolution of signal trajectories, substantially improve this accuracy. Collectively, therefore, the methods we consider here enable a rigorous assessment of the precision, and a significant enhancement of the accuracy, with which stochastic rate constants can be calculated from single-molecule signal trajectories. PMID:27793280

  14. On anthropic solutions of the cosmological constant problem

    NASA Astrophysics Data System (ADS)

    Banks, Tom; Dine, Michael; Motl, Lubos

    2001-01-01

    Motivated by recent work of Bousso and Polchinski (BP), we study theories which explain the small value of the cosmological constant using the anthropic principle. We argue that simultaneous solution of the gauge hierarchy problem is a strong constraint on any such theory. We exhibit three classes of models which satisfy these constraints. The first is a version of the BP model with precisely two large dimensions. The second involves 6-branes and antibranes wrapped on supersymmetric 3-cycles of Calabi-Yau manifolds, and the third is a version of the irrational axion model. All of them have possible problems in explaining the size of microwave background fluctuations. We also find that most models of this type predict that all constants in the low energy lagrangian, as well as the gauge groups and representation content, are chosen from an ensemble and cannot be uniquely determined from the fundamental theory. In our opinion, this significantly reduces the appeal of this kind of solution of the cosmological constant problem. On the other hand, we argue that the vacuum selection problem of string theory might plausibly have an anthropic, cosmological solution.

  15. Constant-pH molecular dynamics using stochastic titration

    NASA Astrophysics Data System (ADS)

    Baptista, António M.; Teixeira, Vitor H.; Soares, Cláudio M.

    2002-09-01

    A new method is proposed for performing constant-pH molecular dynamics (MD) simulations, that is, MD simulations where pH is one of the external thermodynamic parameters, like the temperature or the pressure. The protonation state of each titrable site in the solute is allowed to change during a molecular mechanics (MM) MD simulation, the new states being obtained from a combination of continuum electrostatics (CE) calculations and Monte Carlo (MC) simulation of protonation equilibrium. The coupling between the MM/MD and CE/MC algorithms is done in a way that ensures a proper Markov chain, sampling from the intended semigrand canonical distribution. This stochastic titration method is applied to succinic acid, aimed at illustrating the method and examining the choice of its adjustable parameters. The complete titration of succinic acid, using constant-pH MD simulations at different pH values, gives a clear picture of the coupling between the trans/gauche isomerization and the protonation process, making it possible to reconcile some apparently contradictory results of previous studies. The present constant-pH MD method is shown to require a moderate increase of computational cost when compared to the usual MD method.

  16. Constant DI pacing suppresses cardiac alternans formation in numerical cable models

    NASA Astrophysics Data System (ADS)

    Zlochiver, S.; Johnson, C.; Tolkacheva, E. G.

    2017-09-01

    Cardiac repolarization alternans describe the sequential alternation of the action potential duration (APD) and can develop during rapid pacing. In the ventricles, such alternans may rapidly turn into life risking arrhythmias under conditions of spatial heterogeneity. Thus, suppression of alternans by artificial pacing protocols, or alternans control, has been the subject of numerous theoretical, numerical, and experimental studies. Yet, previous attempts that were inspired by chaos control theories were successful only for a short spatial extent (<2 cm) from the pacing electrode. Previously, we demonstrated in a single cell model that pacing with a constant diastolic interval (DI) can suppress the formation of alternans at high rates of activation. We attributed this effect to the elimination of feedback between the pacing cycle length and the last APD, effectively preventing restitution-dependent alternans from developing. Here, we extend this idea into cable models to study the extent by which constant DI pacing can control alternans during wave propagation conditions. Constant DI pacing was applied to ventricular cable models of up to 5 cm, using human kinetics. Our results show that constant DI pacing significantly shifts the onset of both cardiac alternans and conduction blocks to higher pacing rates in comparison to pacing with constant cycle length. We also demonstrate that constant DI pacing reduces the propensity of spatially discordant alternans, a precursor of wavebreaks. We finally found that the protective effect of constant DI pacing is stronger for increased electrotonic coupling along the fiber in the sense that the onset of alternans is further shifted to higher activation rates. Overall, these results support the potential clinical applicability of such type of pacing in improving protocols of implanted pacemakers, in order to reduce the risk of life-threatening arrhythmias. Future research should be conducted in order to experimentally validate

  17. Cosmological Constant as a Manifestation of the Hierarchy

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

    Chen, Pisin; Gu, Je-An

    2007-12-21

    There has been the suggestion that the cosmological constant as implied by the dark energy is related to the well-known hierarchy between the Planck scale, M{sub PI}, and the Standard Model scale, M{sub SM}. Here we further propose that the same framework that addresses this hierarchy problem must also address the smallness problem of the cosmological constant. Specifically, we investigate the minimal supersymmetric (SUSY) extension of the Randall-Sundrum model where SUSY-breaking is induced on the TeV brane and transmitted into the bulk. We show that the Casimir energy density of the system indeed conforms with the observed dark energy scale.

  18. Equilibrium constant for calcium ion and ascorbate ion.

    PubMed

    Tsao, C S

    1984-02-15

    The combination of calcium and ascorbic acid in water at 25 degrees C has been examined by measuring the change of free calcium ion concentration as ascorbate was added in small increment to a solution of calcium. The data show clearly that complex formation between calcium ion and ascorbate ion occurred. At ionic strength mu = 0.1-0.2, the equilibrium constant of Ca++ and the singly-charged ascorbate ion has been measured to be 2.1 M-1. The precision of the result is better than 5% and the accuracy is estimated to be better than 20%. The application of the equilibrium constants is discussed.

  19. Gladstone-Dale constant for CF4. [experimental design

    NASA Technical Reports Server (NTRS)

    Burner, A. W., Jr.; Goad, W. K.

    1980-01-01

    The Gladstone-Dale constant, which relates the refractive index to density, was measured for CF4 by counting fringes of a two-beam interferometer, one beam of which passes through a cell containing the test gas. The experimental approach and sources of systematic and imprecision errors are discussed. The constant for CF4 was measured at several wavelengths in the visible region of the spectrum. A value of 0.122 cu cm/g with an uncertainty of plus or minus 0.001 cu cm/g was determined for use in the visible region. A procedure for noting the departure of the gas density from the ideal-gas law is discussed.

  20. Brady's Geothermal Field DAS and DTS Surface and Borehole Array Metadata

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

    Dante Fratta

    This metadata submission includes the coordinates of the DAS and DTS surface and borehole arrays, the list of file names, and the list of recorded files during testing at the PoroTomo Natural Laboratory at Brady Hot Spring in Nevada. Testing was completed during March 2016.

  1. Comparison between variable and constant rotor speed operation on WINDMEL-II

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

    Sasamoto, Akira; Matsumiya, Hikaru; Kawamura, Shunji

    1996-10-01

    On a wind turbine control system for rotor revolution speed, it is believed that variable speed operation has the advantages over constant speed from a view point of both aerodynamics and mechanics. However, there is no experimental study which shows the differences. In this report, the authors intend to clarify the differences about shaft torque by using experimental data, from a new wind turbine system which has both variable and constant operation. The result in observation of the experimental data shows that variable speed operational shaft torque is lower than constant speed operational one.

  2. Note: Spring constant calibration of nanosurface-engineered atomic force microscopy cantilevers

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

    Ergincan, O., E-mail: orcunergincan@gmail.com; Palasantzas, G.; Kooi, B. J.

    2014-02-15

    The determination of the dynamic spring constant (k{sub d}) of atomic force microscopy cantilevers is of crucial importance for converting cantilever deflection to accurate force data. Indeed, the non-destructive, fast, and accurate measurement method of the cantilever dynamic spring constant by Sader et al. [Rev. Sci. Instrum. 83, 103705 (2012)] is confirmed here for plane geometry but surface modified cantilevers. It is found that the measured spring constants (k{sub eff}, the dynamic one k{sub d}), and the calculated (k{sub d,1}) are in good agreement within less than 10% error.

  3. The Solar Constant: A Take Home Lab

    ERIC Educational Resources Information Center

    Eaton, B. G.; And Others

    1977-01-01

    Describes a method that uses energy from the sun, absorbed by aluminum discs, to melt ice, and allows the determination of the solar constant. The take-home equipment includes Styrofoam cups, a plastic syringe, and aluminum discs. (MLH)

  4. Examination of Effective Dielectric Constants Derived from Non-Spherical Melting Hydrometeor

    NASA Astrophysics Data System (ADS)

    Liao, L.; Meneghini, R.

    2009-04-01

    The bright band, a layer of enhanced radar echo associated with melting hydrometeors, is often observed in stratiform rain. Understanding the microphysical properties of melting hydrometeors and their scattering and propagation effects is of great importance in accurately estimating parameters of the precipitation from spaceborne radar and radiometers. However, one of the impediments in the study of the radar signature of the melting layer is the determination of effective dielectric constants of melting hydrometeors. Although a number of mixing formulas are available to compute the effective dielectric constants, their results vary to a great extent when water is a component of the mixture, such as in the case of melting snow. It is also physically unclear as to how to select among these various formulas. Furthermore, the question remains as to whether these mixing formulas can be applied to computations of radar polarimetric parameters from non-spherical melting particles. Recently, several approaches using numerical methods have been developed to derive the effective dielectric constants of melting hydrometeors, i.e., mixtures consisting of air, ice and water, based on more realistic melting models of particles, in which the composition of the melting hydrometeor is divided into a number of identical cells. Each of these cells is then assigned in a probabilistic way to be water, ice or air according to the distribution of fractional water contents for a particular particle. While the derived effective dielectric constants have been extensively tested at various wavelengths over a range of particle sizes, these numerical experiments have been restricted to the co-polarized scattering parameters from spherical particles. As polarimetric radar has been increasingly used in the study of microphysical properties of hydrometeors, an extension of the theory to polarimetric variables should provide additional information on melting processes. To account for polarimetric

  5. Colossal dielectric constant up to gigahertz at room temperature

    NASA Astrophysics Data System (ADS)

    Krohns, S.; Lunkenheimer, P.; Kant, Ch.; Pronin, A. V.; Brom, H. B.; Nugroho, A. A.; Diantoro, M.; Loidl, A.

    2009-03-01

    The applicability of recently discovered materials with extremely high ("colossal") dielectric constants, required for future electronics, suffers from the fact that their dielectric constant ɛ' only is huge in a limited frequency range below about 1 MHz. In the present report, we show that the dielectric properties of a charge-ordered nickelate, La15/8Sr1/8NiO4, surpass those of other materials. Especially, ɛ' retains its colossal magnitude of >10 000 well into the gigahertz range.

  6. Experimental determination of third-order elastic constants of diamond.

    PubMed

    Lang, J M; Gupta, Y M

    2011-03-25

    To determine the nonlinear elastic response of diamond, single crystals were shock compressed along the [100], [110], and [111] orientations to 120 GPa peak elastic stresses. Particle velocity histories and elastic wave velocities were measured by using laser interferometry. The measured elastic wave profiles were used, in combination with published acoustic measurements, to determine the complete set of third-order elastic constants. These constants represent the first experimental determination, and several differ significantly from those calculated by using theoretical models.

  7. Rotational Spectra and Nuclear Quadrupole Coupling Constants of Iodoimidazoles

    NASA Astrophysics Data System (ADS)

    Cooper, Graham A.; Anderson, Cara J.; Medcraft, Chris; Legon, Anthony; Walker, Nick

    2017-06-01

    The microwave spectra of two isomers of iodoimidazole have been recorded and assigned with resolution of their nuclear quadrupole coupling constants. These constants have been analysed in terms of the conjugation between the lone pairs on the iodine atom and the aromatic π-bonding system, and the effect of this conjugation on the distribution of π-electron density in the ring. A comparison of these properties has been made between iodoimidazole and other 5- and 6-membered aromatic rings bonded to halogen atoms.

  8. Multiphoton amplitude in a constant background field

    NASA Astrophysics Data System (ADS)

    Ahmad, Aftab; Ahmadiniaz, Naser; Corradini, Olindo; Kim, Sang Pyo; Schubert, Christian

    2018-01-01

    In this contribution, we present our recent compact master formulas for the multiphoton amplitudes of a scalar propagator in a constant background field using the worldline fomulation of quantum field theory. The constant field has been included nonperturbatively, which is crucial for strong external fields. A possible application is the scattering of photons by electrons in a strong magnetic field, a process that has been a subject of great interest since the discovery of astrophysical objects like radio pulsars, which provide evidence that magnetic fields of the order of 1012G are present in nature. The presence of a strong external field leads to a strong deviation from the classical scattering amplitudes. We explicitly work out the Compton scattering amplitude in a magnetic field, which is a process of potential relevance for astrophysics. Our final result is compact and suitable for numerical integration.

  9. Gravity-independent constant force resistive exercise unit

    NASA Technical Reports Server (NTRS)

    Colosky, Jr., Paul E. (Inventor); Ruttley, Tara M. (Inventor)

    2004-01-01

    This invention describes a novel gravity-independent exercise unit designed for use in microgravity, or on the ground, as a means by which to counter muscle atrophy and bone degradation due to disuse or underuse. Modular resistive packs comprising constant torque springs provide constant force opposing the withdrawal of an exercise cable from the device. In addition to uses within the space program, the compact resistive packs of the CFREU allow the unit to be small enough for easy use as a home gym for personal use, or as a supplement for rehabilitation programs. Resistive packs may be changed conveniently out of the CFREU according to the desired exercise regimen. Thus, the resistive packs replace the need for expensive, heavy, and bulky traditional weight plates. The CFREU may be employed by hospitals, rehabilitation and physical therapy clinics, and other related professional businesses.

  10. Distinguishing mechanisms for alternans in cardiac cells using constant-diastolic-interval pacing

    NASA Astrophysics Data System (ADS)

    Cherry, Elizabeth M.

    2017-09-01

    Alternans, a proarrhythmic dynamical state in which cardiac action potentials alternate between long and short durations despite a constant pacing period, traditionally has been explained at the cellular level using nonlinear dynamics principles under the assumption that the action potential duration (APD) is determined solely by the time elapsed since the end of the previous action potential, called the diastolic interval (DI). In this scenario, APDs at a steady state should be the same provided that the preceding DIs are the same. Nevertheless, experiments attempting to eliminate alternans by dynamically adjusting the timing of pacing stimuli to keep the DI constant showed that alternans persisted, contradicting the traditional theory. It is now widely known that alternans also can arise from a different mechanism associated with intracellular calcium cycling. Our goal is to determine whether intracellular calcium dynamics can explain the experimental findings regarding the persistence of alternans despite a constant DI. For this, we use mathematical models capable of producing alternans through both voltage- and calcium-mediated mechanisms. We show that for voltage-driven alternans, action potentials elicited from a constant-DI protocol are always the same. However, in the case of calcium-driven alternans, the constant-DI protocol can result in alternans. Reducing the strength of the calcium instability progressively reduces and finally eliminates constant-DI alternans. Our findings suggest that screening for the presence of alternans using a constant-DI protocol has the potential for differentiating between voltage-driven and calcium-driven alternans.

  11. Integriertes Informationsmanagement an der Westfälischen Wilhelms-Universität Münster - Das Projekt MIRO

    NASA Astrophysics Data System (ADS)

    Vogl, Raimund; Gildhorn, Antje; Labitzke, Jörg; Wibberg, Michael

    An der Westfälischen Wilhelms-Universität Münster (WWU) wurde bereits 1996 ein tragfähiges, kooperativ ausgerichtetes System der IT-Governance im Zusammenspiel zentraler und dezentraler IT-Leistungserbringer etabliert. Um den Anforderungen an ein integriertes Informationsmanagement im Überlappungsfeld von Information, Kommunikation und Medien (IKM) durch das Zusammenspiel der zentralen Einrichtungen Universitätsverwaltung (UniV), Universitäts- und Landesbibliothek (ULB) und Zentrum für Informationsverarbeitung (ZIV) gerecht zu werden, wurde 2003 der IKM-Service institutionalisiert. In diesem Rahmen wurde das Projekt Münster Information System for Research and Organization (MIRO) entwickelt, das als Leistungszentrum für Forschungsinformation von der DFG gefördert wird. Die bisherigen Projekterfahrungen, erreichten Ziele und verbleibenden Aufgaben werden dargestellt. Im Projektverlauf haben sich insbesondere die etablierten IT-Governance und Versorgungs-Strukturen sowie die Unterstützung der Hochschulleitung als essentielle Erfolgskriterien erwiesen.

  12. Effect of Cold Temperature on the Dielectric Constant of Soil

    DTIC Science & Technology

    2012-04-01

    explosive device (IED) threats is ground-penetrating radar ( GPR ). Proper development of GPR technology for this application requires a unique...success or failure of GPR as a detection technique. One soil property of interest to radar engineers is the dielectric constant. Previous...results to temperatures, moisture levels, and frequencies relevant to GPR systems. 2. Dielectric Constant and the Ring-resonator Concept The two

  13. Colossal dielectric constant in PrFeO 3 semiconductor ceramics

    NASA Astrophysics Data System (ADS)

    Prasad, Bandi Vittal; Rao, G. Narsinga; Chen, J. W.; Babu, D. Suresh

    2012-02-01

    The perovskite PrFeO 3 ceramics were synthesized via sol-gel method. The dielectric properties and impedance spectroscopy (IS) of these ceramics were studied in the frequency range from 100 Hz to 1000 kHz in the temperature range from 80 K to 300 K. These materials exhibited colossal dielectric constant value of ˜10 4 at room temperature. The response is similar to that observed for relaxorferroelectrics. IS data analysis indicates the ceramics to be electrically heterogeneous semiconductor consisting of semiconducting grains with dielectric constant 30 and more resistive grain boundaries with effective dielectric constant ˜10 4. We conclude, therefore that grain boundary effect is the primary source for the high effective permittivity in PrFeO 3 ceramics.

  14. Spectroscopic Constants of the Known Electronic States of Lead Monofluoride

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

    McRaven, C.P.; Sivakumar, P.; Shafer-Ray, N.E.

    2010-08-01

    Based on measurements made by mass-resolved 1 + 1{prime} + 1{double_prime} resonance-enhanced multiphoton ionization spectroscopy, we have determined new molecular constants describing the rotational and fine structure levels of the B, D, E, and F states of the most abundant isotopic variant {sup 208}Pb{sup 19}F, and we summarize the spectroscopic constants for all the know electronic states of the radical. Many spectroscopic constants for the isotopologues {sup 206}Pb{sup 19}F and {sup 207}Pb{sup 19}F have also been determined. The symmetry of the D-state is found to be {sup 2}{pi}{sub 1/2}, and the F-state is found to be an {Omega} = 3/2more » state.« less

  15. Synthesis and Characterization of High-Dielectric-Constant Nanographite-Polyurethane Composite

    NASA Astrophysics Data System (ADS)

    Mishra, Praveen; Bhat, Badekai Ramachandra; Bhattacharya, B.; Mehra, R. M.

    2018-05-01

    In the face of ever-growing demand for capacitors and energy storage devices, development of high-dielectric-constant materials is of paramount importance. Among various dielectric materials available, polymer dielectrics are preferred for their good processability. We report herein synthesis and characterization of nanographite-polyurethane composite with high dielectric constant. Nanographite showed good dispersibility in the polyurethane matrix. The thermosetting nature of polyurethane gives the composite the ability to withstand higher temperature without melting. The resultant composite was studied for its dielectric constant (ɛ) as a function of frequency. The composite exhibited logarithmic variation of ɛ from 3000 at 100 Hz to 225 at 60 kHz. The material also exhibited stable dissipation factor (tan δ) across the applied frequencies, suggesting its ability to resist current leakage.

  16. Constant-Current Source For Measuring Low Resistances

    NASA Technical Reports Server (NTRS)

    Toomath, Robert L.

    1996-01-01

    Constant-current source constructed for measuring electrical resistances up to few ohms in power-supply equipment. By setting current at 1 A and measuring resulting voltage drop across item under test, one obtains voltage reading numerically equal to resistance in ohms.

  17. Calibration of the k- ɛ model constants for use in CFD applications

    NASA Astrophysics Data System (ADS)

    Glover, Nina; Guillias, Serge; Malki-Epshtein, Liora

    2011-11-01

    The k- ɛ turbulence model is a popular choice in CFD modelling due to its robust nature and the fact that it has been well validated. However it has been noted in previous research that the k- ɛ model has problems predicting flow separation as well as unconfined and transient flows. The model contains five empirical model constants whose values were found through data fitting for a wide range of flows (Launder 1972) but ad-hoc adjustments are often made to these values depending on the situation being modeled. Here we use the example of flow within a regular street canyon to perform a Bayesian calibration of the model constants against wind tunnel data. This allows us to assess the sensitivity of the CFD model to changes in these constants, find the most suitable values for the constants as well as quantifying the uncertainty related to the constants and the CFD model as a whole.

  18. Nuclear shielding constants by density functional theory with gauge including atomic orbitals

    NASA Astrophysics Data System (ADS)

    Helgaker, Trygve; Wilson, Philip J.; Amos, Roger D.; Handy, Nicholas C.

    2000-08-01

    Recently, we introduced a new density-functional theory (DFT) approach for the calculation of NMR shielding constants. First, a hybrid DFT calculation (using 5% exact exchange) is performed on the molecule to determine Kohn-Sham orbitals and their energies; second, the constants are determined as in nonhybrid DFT theory, that is, the paramagnetic contribution to the constants is calculated from a noniterative, uncoupled sum-over-states expression. The initial results suggested that this semiempirical DFT approach gives shielding constants in good agreement with the best ab initio and experimental data; in this paper, we further validate this procedure, using London orbitals in the theory, having implemented DFT into the ab initio code DALTON. Calculations on a number of small and medium-sized molecules confirm that our approach produces shieldings in excellent agreement with experiment and the best ab initio results available, demonstrating its potential for the study of shielding constants of large systems.

  19. Comparison of Distributed Acoustic Sensing (DAS) from Fiber-Optic Cable to Three Component Geophones in an Underground Mine

    NASA Astrophysics Data System (ADS)

    Speece, M. A.; Nesladek, N. J.; Kammerer, C.; Maclaughlin, M.; Wang, H. F.; Lord, N. E.

    2017-12-01

    We conducted experiments in the Underground Education Mining Center on the Montana Tech campus, Butte, Montana, to make a direct comparison between Digital Acoustic Sensing (DAS) and three-component geophones in a mining setting. The sources used for this project where a vertical sledgehammer, oriented shear sledgehammer, and blasting caps set off in both unstemmed and stemmed drillholes. Three-component Geospace 20DM geophones were compared with three different types of fiber-optic cable: (1) Brugg strain, (2) Brugg temperature, and (3) Optical Cable Corporation strain. We attached geophones to the underground mine walls and on the ground surface above the mine. We attached fiber-optic cables to the mine walls and placed fiber-optic cable in boreholes drilled through an underground pillar. In addition, we placed fiber-optic cables in a shallow trench at the surface of the mine. We converted the DAS recordings from strain rate to strain prior to comparison with the geophone data. The setup of the DAS system for this project led to a previously unknown triggering problem that compromised the early samples of the DAS traces often including the first-break times on the DAS records. Geophones clearly recorded the explosives; however, the large amount of energy and its close distance from the fiber-optic cables seemed to compromise the entire fiber loop. The underground hammer sources produced a rough match between the DAS records and the geophone records. However, the sources on the surface of the mine, specifically the sources oriented inline with the fiber-optic cables, produced a close match between the fiber-optic traces and the geophone traces. All three types of fiber-optic cable that were in the mine produced similar results, and one type did not clearly outperform the others. Instead, the coupling of the cable to rock appears to be the most important factor determining DAS data quality. Moreover, we observed the importance of coupling in the boreholes, where

  20. Rate constant for reaction of atomic hydrogen with germane

    NASA Technical Reports Server (NTRS)

    Nava, David F.; Payne, Walter A.; Marston, George; Stief, Louis J.

    1990-01-01

    Due to the interest in the chemistry of germane in the atmospheres of Jupiter and Saturn, and because previously reported kinetic reaction rate studies at 298 K gave results differing by a factor of 200, laboratory measurements were performed to determine the reaction rate constant for H + GeH4. Results of the study at 298 K, obtained via the direct technique of flash photolysis-resonance fluorescence, yield the reaction rate constant, k = (4.08 + or - 0.22) x 10(exp -12) cu cm/s.

  1. EHealth: self-management in inflammatory bowel disease and in irritable bowel syndrome using novel constant-care web applications. EHealth by constant-care in IBD and IBS.

    PubMed

    Pedersen, Natalia

    2015-12-01

    Inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS) are chronic gastrointestinal disorders of unknown aetiology of increasing incidence and changing disease activity or severity. Approximately 60-80% of IBD patients suffer from IBS. Monitoring and treatment goals of IBD are to optimise the disease course by prolonging remission periods and preventing or shortening periods of active disease. Constant-care web-monitoring and treatment approaches with active patient involvement have been proven effective in UC, increasing patients' adherence and improving the disease outcomes.   To assess the feasibility and efficacy of the novel constant-care eHealth applications in: i) CD patients treated with infliximab (IFX), ii) UC patients with active disease on mesalazine, iii) IBS patients and iv) IBD patients with IBS on a low FODMAP diet (LFD).   New constant-care web applications www.cd.constant-care.dk, www.meza.constant-care.dk and www.ibs.constant-care.dk in IBD patients were developed and assessed in this thesis. An integrated inflammatory burden measure of disease activity, consisting of a subjective (clinical indices) and of an objective (faecal calprotectin) part and a treatment guide to drug doses and intervals, was incorporated into the web applications and used by patients. Web-guided IFX treatment in CD demonstrated patients' inter- and intra-individual variability in infusion intervals and provided patients with individualised treatment according to their needs. Web-guided treatment with multimatrix mesalazine was efficacious in a majority of UC patients with mild-to-moderate disease activity. Web-guided IBS-monitoring in IBD and in IBS patients on LFD was shown to be a feasible method that actively involved patients in their disease management and had a positive short-term impact on the disease. Moreover, the new constant-care concepts were demonstrated to be safe and to have a positive impact on quality of life and adherence to treatment and

  2. Apparatus producing constant cable tension for intermittent demand

    DOEpatents

    Lauritzen, Ted

    1985-01-01

    The disclosed apparatus produces constant tension in superconducting electrical cable, or some other strand, under conditions of intermittent demand, as the cable is unreeled from a reel or reeled thereon. The apparatus comprises a pivotally supported swing frame on which the reel is rotatably supported, a rotary motor, a drive train connected between the motor and the reel and including an electrically controllable variable torque slip clutch, a servo transducer connected to the swing frame for producing servo input signals corresponding to the position thereof, a servo control system connected between the transducer and the clutch for regulating the torque transmitted by the clutch to maintain the swing frame in a predetermined position, at least one air cylinder connected to the swing frame for counteracting the tension in the cable, and pressure regulating means for supplying a constant air pressure to the cylinder to establish the constant tension in the cable, the servo system and the clutch being effective to produce torque on the reel in an amount sufficient to provide tension in the cable corresponding to the constant force exerted by the air cylinder. The drive train also preferably includes a fail-safe brake operable to its released position by electrical power in common with the servo system, for preventing rotation of the reel if there is a power failure. A shock absorber and biasing springs may also be connected to the swing frame, such springs biasing the frame toward its predetermined position. The tension in the cable may be measured by force measuring devices engageable with the bearings for the reel shaft, such bearings being supported for slight lateral movement. The reel shaft is driven by a Shmidt coupler which accommodates such movement.

  3. Transient times in linear metabolic pathways under constant affinity constraints.

    PubMed

    Lloréns, M; Nuño, J C; Montero, F

    1997-10-15

    In the early seventies, Easterby began the analytical study of transition times for linear reaction schemes [Easterby (1973) Biochim. Biophys. Acta 293, 552-558]. In this pioneer work and in subsequent papers, a state function (the transient time) was used to measure the period before the stationary state, for systems constrained to work under both constant and variable input flux, was reached. Despite the undoubted usefulness of this quantity to describe the time-dependent features of these kinds of systems, its application to the study of chemical reactions under other constraints is questionable. In the present work, a generalization of these magnitudes to linear metabolic pathways functioning under a constant-affinity constraint is carried out. It is proved that classical definitions of transient times do not reflect the actual properties of the transition to the steady state in systems evolving under this restriction. Alternatively, a more adequate framework for interpretation of the transient times for systems with both constant and variable input flux is suggested. Within this context, new definitions that reflect more accurately the transient characteristics of constant affinity systems are stated. Finally, the meaning of these transient times is discussed.

  4. Radii effect on the translation spring constant of force transducer beams

    NASA Technical Reports Server (NTRS)

    Scott, C. E.

    1992-01-01

    Multi-component strain-gage force transducer design requires the designer to determine the spring constant of the numerous beams or flexures incorporated in the transducer. The classical beam deflection formulae that are used in calculating these spring constants typically assume that the beam has a uniform moment of inertia along the entire beam length. In practice all beams have a radius at the end where the beam interfaces with the shoulder of the transducer, and on short beams in particular this increases the beam spring constant considerably. A Basic computer program utilizing numerical integration is presented to determine this effect.

  5. Semi-empirical proton binding constants for natural organic matter

    NASA Astrophysics Data System (ADS)

    Matynia, Anthony; Lenoir, Thomas; Causse, Benjamin; Spadini, Lorenzo; Jacquet, Thierry; Manceau, Alain

    2010-03-01

    Average proton binding constants ( KH,i) for structure models of humic (HA) and fulvic (FA) acids were estimated semi-empirically by breaking down the macromolecules into reactive structural units (RSUs), and calculating KH,i values of the RSUs using linear free energy relationships (LFER) of Hammett. Predicted log KH,COOH and log KH,Ph-OH are 3.73 ± 0.13 and 9.83 ± 0.23 for HA, and 3.80 ± 0.20 and 9.87 ± 0.31 for FA. The predicted constants for phenolic-type sites (Ph-OH) are generally higher than those derived from potentiometric titrations, but the difference may not be significant in view of the considerable uncertainty of the acidity constants determined from acid-base measurements at high pH. The predicted constants for carboxylic-type sites agree well with titration data analyzed with Model VI (4.10 ± 0.16 for HA, 3.20 ± 0.13 for FA; Tipping, 1998), the Impermeable Sphere model (3.50-4.50 for HA; Avena et al., 1999), and the Stockholm Humic Model (4.10 ± 0.20 for HA, 3.50 ± 0.40 for FA; Gustafsson, 2001), but differ by about one log unit from those obtained by Milne et al. (2001) with the NICA-Donnan model (3.09 ± 0.51 for HA, 2.65 ± 0.43 for FA), and used to derive recommended generic values. To clarify this ambiguity, 10 high-quality titration data from Milne et al. (2001) were re-analyzed with the new predicted equilibrium constants. The data are described equally well with the previous and new sets of values ( R2 ⩾ 0.98), not necessarily because the NICA-Donnan model is overparametrized, but because titration lacks the sensitivity needed to quantify the full binding properties of humic substances. Correlations between NICA-Donnan parameters are discussed, but general progress is impeded by the unknown number of independent parameters that can be varied during regression of a model fit to titration data. The high consistency between predicted and experimental KH,COOH values, excluding those of Milne et al. (2001), gives faith in the proposed

  6. Quantum-gravity predictions for the fine-structure constant

    NASA Astrophysics Data System (ADS)

    Eichhorn, Astrid; Held, Aaron; Wetterich, Christof

    2018-07-01

    Asymptotically safe quantum fluctuations of gravity can uniquely determine the value of the gauge coupling for a large class of grand unified models. In turn, this makes the electromagnetic fine-structure constant calculable. The balance of gravity and matter fluctuations results in a fixed point for the running of the gauge coupling. It is approached as the momentum scale is lowered in the transplanckian regime, leading to a uniquely predicted value of the gauge coupling at the Planck scale. The precise value of the predicted fine-structure constant depends on the matter content of the grand unified model. It is proportional to the gravitational fluctuation effects for which computational uncertainties remain to be settled.

  7. Some Dynamical Effects of the Cosmological Constant

    NASA Astrophysics Data System (ADS)

    Axenides, M.; Floratos, E. G.; Perivolaropoulos, L.

    Newton's law gets modified in the presence of a cosmological constant by a small repulsive term (antigravity) that is proportional to the distance. Assuming a value of the cosmological constant consistent with the recent SnIa data (Λ~=10-52 m-2), we investigate the significance of this term on various astrophysical scales. We find that on galactic scales or smaller (less than a few tens of kpc), the dynamical effects of the vacuum energy are negligible by several orders of magnitude. On scales of 1 Mpc or larger however we find that the vacuum energy can significantly affect the dynamics. For example we show that the velocity data in the local group of galaxies correspond to galactic masses increased by 35% in the presence of vacuum energy. The effect is even more important on larger low density systems like clusters of galaxies or superclusters.

  8. BOREAS RSS-17 Dielectric Constant Profile Measurements

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Nickeson, Jaime (Editor); McDonald, Kyle C.; Zimmerman, Reiner; Way, JoBea

    2000-01-01

    The BOREAS RSS-17 team acquired and analyzed imaging radar data from the ESA's ERS-1 over a complete annual cycle at the BOREAS sites in Canada in 1994 to detect shifts in radar backscatter related to varying environmental conditions. This data set consists of dielectric constant profile measurements from selected trees at various BOREAS flux tower sites. The relative dielectric constant was measured at C-band (frequency = 5 GHz) as a function of depth into the trunk of three trees at each site, Measurements were made during April 1994 with an Applied Microwave Corporation field PDP fitted with a 0.358-cm (0.141-inch) diameter coaxial probe tip. The data are available in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  9. Voicing produced by a constant velocity lung source

    PubMed Central

    Howe, M. S.; McGowan, R. S.

    2013-01-01

    An investigation is made of the influence of subglottal boundary conditions on the prediction of voiced sounds. It is generally assumed in mathematical models of voicing that vibrations of the vocal folds are maintained by a constant subglottal mean pressure pI, whereas voicing is actually initiated by contraction of the chest cavity until the subglottal pressure becomes large enough to separate the vocal folds. The problem is reformulated to determine voicing characteristics in terms of a prescribed volumetric flow rate Qo of air from the lungs—the evolution of the resulting time-dependent subglottal mean pressure p¯_(t) is then governed by glottal mechanics, the aeroacoustics of the vocal tract, and the influence of continued contraction of the lungs. The new problem is analyzed in detail for an idealized mechanical vocal system that permits precise specification of all boundary conditions. Predictions of the glottal volume velocity pulse shape are found to be in good general agreement with the traditional constant-pI theory when pI is set equal to the time averaged value of p¯_(t). But, in all cases examined the constant-pI approximation yields values of the mean flow rates Qo and sound pressure levels that are smaller by as much as 10%. PMID:23556600

  10. The DAS28-ESR cutoff value necessary to achieve remission under the new Boolean-based remission criteria in patients receiving tocilizumab.

    PubMed

    Hirabayashi, Yasuhiko; Ishii, Tomonori

    2013-01-01

    To seek the cutoff value of the 28-joint disease activity score using erythrocyte sedimentation rate (DAS28-ESR) that is necessary to achieve remission under the new Boolean-based criteria, we analyzed the data for 285 patients with rheumatoid arthritis registered between May 2008 and November 2009 by the Michinoku Tocilizumab Study Group and observed for 1 year after receiving tocilizumab (TCZ) in real clinical practice. Remission rates under the DAS28-ESR criteria and the Boolean criteria were assessed every 6 months after the first TCZ dose. The DAS28-ESR cutoff value necessary to achieve remission under the new criteria was analyzed by receiver operating characteristic (ROC) analysis. Data were analyzed using last observation carried forward. After 12 months of TCZ use, remission was achieved in 164 patients (57.5 %) by DAS28-ESR and 71 patients (24.9 %) under the new criteria for clinical trials. CRP levels scarcely affected remission rates, and the difference between remission rates defined by DAS28-ESR and by the new criteria was mainly due to patient global assessment (PGA). Improvement of PGA was inversely related to disease duration. ROC analysis revealed that the DAS28-ESR cutoff value necessary to predict remission under the new criteria for clinical trials was 1.54, with a sensitivity of 88.7 %, specificity of 85.5 %, positive predictive value of 67.0 %, and negative predictive value of 95.8 %. A DAS28-ESR cutoff value of 1.54 may be reasonable to predict achievement of remission under the new Boolean-based criteria for clinical trials in patients receiving TCZ.

  11. Low noise constant current source for bias dependent noise measurements

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

    Talukdar, D.; Bose, Suvendu; Bardhan, K. K.

    2011-01-15

    A low noise constant current source used for measuring the 1/f noise in disordered systems in ohmic as well as nonohmic regime is described. The source can supply low noise constant current starting from as low as 1 {mu}A to a few tens of milliampere with a high voltage compliance limit of around 20 V. The constant current source has several stages, which can work in a standalone manner or together to supply the desired value of load current. The noise contributed by the current source is very low in the entire current range. The fabrication of a low noisemore » voltage preamplifier modified for bias dependent noise measurements and based on the existing design available in the MAT04 data sheet is also described.« less

  12. The rate constant of a quantum-diffusion-controlled bimolecular reaction

    NASA Astrophysics Data System (ADS)

    Bondarev, B. V.

    1986-04-01

    A quantum-mechanical equation is derived in the tight-bond approximation which describes the motion and chemical interaction of a pair of species A and B when their displacement in the matrix is caused by tunnelling. Within the framework of the discrete model of random walks, definitions are given of the probability and rate constant of a reaction A + B → P (products) proceeding in a condensed medium. A method is suggested for calculating the rate constant of a quantum-diffusion-controlled bimolecular reaction. By this method, an expression is obtained for the rate constant in the stationary spherically symmetrical case. An equation for the density matrix is also proposed which describes the motion and chemical interaction of a pair of species when the quantum and classical diffusion are competitive.

  13. Holographic dark energy with cosmological constant

    NASA Astrophysics Data System (ADS)

    Hu, Yazhou; Li, Miao; Li, Nan; Zhang, Zhenhui

    2015-08-01

    Inspired by the multiverse scenario, we study a heterotic dark energy model in which there are two parts, the first being the cosmological constant and the second being the holographic dark energy, thus this model is named the ΛHDE model. By studying the ΛHDE model theoretically, we find that the parameters d and Ωhde are divided into a few domains in which the fate of the universe is quite different. We investigate dynamical behaviors of this model, and especially the future evolution of the universe. We perform fitting analysis on the cosmological parameters in the ΛHDE model by using the recent observational data. We find the model yields χ2min=426.27 when constrained by Planck+SNLS3+BAO+HST, comparable to the results of the HDE model (428.20) and the concordant ΛCDM model (431.35). At 68.3% CL, we obtain -0.07<ΩΛ0<0.68 and correspondingly 0.04<Ωhde0<0.79, implying at present there is considerable degeneracy between the holographic dark energy and cosmological constant components in the ΛHDE model.

  14. Ocean Color Measurements from Landsat-8 OLI using SeaDAS

    NASA Technical Reports Server (NTRS)

    Franz, Bryan Alden; Bailey, Sean W.; Kuring, Norman; Werdell, P. Jeremy

    2014-01-01

    The Operational Land Imager (OLI) is a multi-spectral radiometer hosted on the recently launched Landsat-8 satellite. OLI includes a suite of relatively narrow spectral bands at 30-meter spatial resolution in the visible to shortwave infrared that make it a potential tool for ocean color radiometry: measurement of the reflected spectral radiance upwelling from beneath the ocean surface that carries information on the biogeochemical constituents of the upper ocean euphotic zone. To evaluate the potential of OLI to measure ocean color, processing support was implemented in SeaDAS, which is an open-source software package distributed by NASA for processing, analysis, and display of ocean remote sensing measurements from a variety of satellite-based multi-spectral radiometers. Here we describe the implementation of OLI processing capabilities within SeaDAS, including support for various methods of atmospheric correction to remove the effects of atmospheric scattering and absorption and retrieve the spectral remote-sensing reflectance (Rrs; sr exp 1). The quality of the retrieved Rrs imagery will be assessed, as will the derived water column constituents such as the concentration of the phytoplankton pigment chlorophyll a.

  15. Computer Calculation of First-Order Rate Constants

    ERIC Educational Resources Information Center

    Williams, Robert C.; Taylor, James W.

    1970-01-01

    Discusses the computer program used to calculate first-order rate constants. Discussion includes data preparation, weighting options, comparison techniques, infinity point adjustment, least-square fit, Guggenheim calculation, and printed outputs. Exemplifies the utility of the computer program by two experiments: (1) the thermal decomposition of…

  16. The effect of diamic acid additives on the dielectric constant of polyimides

    NASA Technical Reports Server (NTRS)

    Stoakley, Diane M.; St. Clair, Anne K.

    1988-01-01

    The effect of six selected diamic acids additives (including 2,2-prime bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride-aniline (An); 4,4-prime-oxydiphthalic anhydride-An, 3,3-prime diaminodiphenyl sulfone-phthalic anhydride (PA); 4,4-prime-oxydianiline-PA; 2,2-bis 4(4-aminophenoxy)phenyl hexafluoropropane-PA; and 2,2-bis 4(3-aminophenoxy)phenyl hexafluoropropane-PA) on the dielectric constants of low-dielectric-constant polyimide resins was evaluated. It was found that the effect of the incorporation of the diamic acids on reducing the dielectric constant of polyimides may be limited as the dielectric constant of the base resin itself becomes very low. The additives were found to lower the resin's values of glass transition temperature, with no effect on thermooxidative stability.

  17. Constitutive Model Constants for Al7075-T651 and Al7075-T6

    NASA Astrophysics Data System (ADS)

    Brar, N. S.; Joshi, V. S.; Harris, B. W.

    2009-12-01

    Aluminum 7075-T651 and 7075-T6 are characterized at quasi-static and high strain rates to determine Johnson-Cook (J-C) strength and fracture model constants. Constitutive model constants are required as input to computer codes to simulate projectile (fragment) impact or similar impact events on structural components made of these materials. Although the two tempers show similar elongation at breakage, the ultimate tensile strength of T651 temper is generally lower than the T6 temper. Johnson-Cook strength model constants (A, B, n, C, and m) for the two alloys are determined from high strain rate tension stress-strain data at room and high temperature to 250°C. The Johnson-Cook fracture model constants are determined from quasi-static and medium strain rate as well as high temperature tests on notched and smooth tension specimens. Although the J-C strength model constants are similar, the fracture model constants show wide variations. Details of the experimental method used and the results for the two alloys are presented.

  18. The transmembrane gradient of the dielectric constant influences the DPH lifetime distribution.

    PubMed

    Konopásek, I; Kvasnicka, P; Amler, E; Kotyk, A; Curatola, G

    1995-11-06

    The fluorescence lifetime distribution of 1,6-diphenyl-1,3,5-hexatriene (DPH) and 1-[4-(trimethylamino)phenyl]-6-phenyl-1,3,5-hexatriene (TMA-DPH) in egg-phosphatidylcholine liposomes was measured in normal and heavy water. The lower dielectric constant (by approximately 12%) of heavy water compared with normal water was employed to provide direct evidence that the drop of the dielectric constant along the membrane normal shifts the centers of the distribution of both DPH and TMA-DPH to higher values and sharpens the widths of the distribution. The profile of the dielectric constant along the membrane normal was not found to be a linear gradient (in contrast to [1]) but a more complex function. Presence of cholesterol in liposomes further shifted the center of the distributions to higher value and sharpened them. In addition, it resulted in a more gradient-like profile of the dielectric constant (i.e. linearization) along the normal of the membrane. The effect of the change of dielectric constant on the membrane proteins is discussed.

  19. Determination of elastic constants of a generally orthotropic plate by modal analysis

    NASA Astrophysics Data System (ADS)

    Lai, T. C.; Lau, T. C.

    1993-01-01

    This paper describes a method of finding the elastic constants of a generally orthotropic composite thin plate through modal analysis based on a Rayleigh-Ritz formulation. The natural frequencies and mode shapes for a plate with free-free boundary conditions are obtained with chirp excitation. Based on the eigenvalue equation and the constitutive equations of the plate, an iteration scheme is derived using the experimentally determined natural frequencies to arrive at a set of converged values for the elastic constants. Four sets of experimental data are required for the four independent constants: namely the two Young's moduli E1 and E2, the in-plane shear modulus G12, and one Poisson's ratio nu12. The other Poisson's ratio nu21 can then be determined from the relationship among the constants. Comparison with static test results indicate good agreement. Choosing the right combinations of natural modes together with a set of reasonable initial estimates for the constants to start the iteration has been found to be crucial in achieving convergence.

  20. Defect-induced change of temperature-dependent elastic constants in BCC iron

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

    Gao, N.; Setyawan, W.; Zhang, S. H.

    2017-07-01

    The effects of radiation-induced defects (randomly distributed vacancies, voids, and interstitial dislocation loops) on temperature-dependent elastic constants, C11, C12, and C44 in BCC iron, are studied with molecular dynamics method. The elastic constants are found to decrease with increasing temperatures for all cases containing different defects. The presence of vacancies, voids, or interstitial loops further decreases the elastic constants. For a given number of point defects, the randomly distributed vacancies show the strongest effect compared to voids or interstitial loops. All these results are expected to provide useful information to combine with experimental results for further understanding of radiation damage.

  1. On the Law of Inertia. Translation of: Ueber das Beharrungsgesetz

    NASA Astrophysics Data System (ADS)

    Lange, Ludwig

    2014-04-01

    This article is a translation of Ludwig Lange: "Ueber das Beharrungsgesetz" in: Berichte ueber Verhandlungen der Koenigl. Saechsischen Gesellschaft der Wissenschaften, math.-physik. Klasse (Leipzig, 1885), SS. 333-351. Translated by Herbert Pfister, Institut für Theoretische Physik, Universität Tübingen, Auf der Morgenstelle 14, 72076 Tübingen, Germany; herbert.pfister@uni-tuebingen.de. Kind assistance by Julian Barbour is acknowledged.

  2. Time constant determination for electrical equivalent of biological cells

    NASA Astrophysics Data System (ADS)

    Dubey, Ashutosh Kumar; Dutta-Gupta, Shourya; Kumar, Ravi; Tewari, Abhishek; Basu, Bikramjit

    2009-04-01

    The electric field interactions with biological cells are of significant interest in various biophysical and biomedical applications. In order to study such important aspect, it is necessary to evaluate the time constant in order to estimate the response time of living cells in the electric field (E-field). In the present study, the time constant is evaluated by considering the hypothesis of electrical analog of spherical shaped cells and assuming realistic values for capacitance and resistivity properties of cell/nuclear membrane, cytoplasm, and nucleus. In addition, the resistance of cytoplasm and nucleoplasm was computed based on simple geometrical considerations. Importantly, the analysis on the basis of first principles shows that the average values of time constant would be around 2-3 μs, assuming the theoretical capacitance values and the analytically computed resistance values. The implication of our analytical solution has been discussed in reference to the cellular adaptation processes such as atrophy/hypertrophy as well as the variation in electrical transport properties of cellular membrane/cytoplasm/nuclear membrane/nucleoplasm.

  3. Lattice constant in nonstoichiometric uranium dioxide from first principles

    NASA Astrophysics Data System (ADS)

    Bruneval, Fabien; Freyss, Michel; Crocombette, Jean-Paul

    2018-02-01

    Nonstoichiometric uranium dioxide experiences a shrinkage of its lattice constant with increasing oxygen content, in both the hypostoichiometric and the hyperstoichiometric regimes. Based on first-principles calculations within the density functional theory (DFT)+U approximation, we have developed a point defect model that accounts for the volume of relaxation of the most significant intrinsic defects of UO2. Our point defect model takes special care of the treatment of the charged defects in the equilibration of the model and in the determination of reliable defect volumes of formation. In the hypostoichiometric regime, the oxygen vacancies are dominant and explain the lattice constant variation with their surprisingly positive volume of relaxation. In the hyperstoichiometric regime, the uranium vacancies are predicted to be the dominating defect,in contradiction with experimental observations. However, disregarding uranium vacancies allows us to recover a good match for the lattice-constant variation as a function of stoichiometry. This can be considered a clue that the uranium vacancies are indeed absent in UO2 +x, possibly due to the very slow diffusion of uranium.

  4. A constant current charge technique for low Earth orbit life testing

    NASA Technical Reports Server (NTRS)

    Glueck, Peter

    1991-01-01

    A constant current charge technique for low earth orbit testing of nickel cadmium cells is presented. The method mimics the familiar taper charge of the constant potential technique while maintaining cell independence for statistical analysis. A detailed example application is provided and the advantages and disadvantages of this technique are discussed.

  5. Effective Torsion and Spring Constants in a Hybrid Translational-Rotational Oscillator

    ERIC Educational Resources Information Center

    Nakhoda, Zein; Taylor, Ken

    2011-01-01

    A torsion oscillator is a vibrating system that experiences a restoring torque given by [tau] = -[kappa][theta] when it experiences a rotational displacement [theta] from its equilibrium position. The torsion constant [kappa] (kappa) is analogous to the spring constant "k" for the traditional translational oscillator (for which the restoring force…

  6. Validation of Land-Surface Mosaic Heterogeneity in the GEOS DAS

    NASA Technical Reports Server (NTRS)

    Bosilovich, Michael G.; Molod, Andrea; Houser, Paul R.; Schubert, Siegfried

    1999-01-01

    The Mosaic Land-surface Model (LSM) has been included into the current GEOS Data Assimilation System (DAS). The LSM uses a more advanced representation of physical processes than previous versions of the GEOS DAS, including the representation of sub-grid heterogeneity of the land-surface through the Mosaic approach. As a first approximation, Mosaic assumes that all similar surface types within a grid-cell can be lumped together as a single'tile'. Within one GCM grid-cell, there might be 1 - 5 different tiles or surface types. All tiles are subjected to the grid-scale forcing (radiation, air temperature and specific humidity, and precipitation), and the sub-grid variability is a function of the tile characteristics. In this paper, we validate the LSM sub-grid scale variability (tiles) using a variety of surface observing stations from the Southern Great Plains (SGP) site of the Atmospheric Radiation Measurement (ARM) Program. One of the primary goals of SGP ARM is to study the variability of atmospheric radiation within a G,CM grid-cell. Enough surface data has been collected by ARM to extend this goal to sub-grid variability of the land-surface energy and water budgets. The time period of this study is the Summer of 1998 (June I - September 1). The ARM site data consists of surface meteorology, energy flux (eddy correlation and bowen ratio), soil water observations spread over an area similar to the size of a G-CM grid-cell. Various ARM stations are described as wheat and alfalfa crops, pasture and range land. The LSM tiles considered at the grid-space (2 x 2.5) nearest the ARM site include, grassland, deciduous forests, bare soil and dwarf trees. Surface energy and water balances for each tile type are compared with observations. Furthermore, we will discuss the land-surface sub-grid variability of both the ARM observations and the DAS.

  7. Fundamental constants and high-resolution spectroscopy

    NASA Astrophysics Data System (ADS)

    Bonifacio, P.; Rahmani, H.; Whitmore, J. B.; Wendt, M.; Centurion, M.; Molaro, P.; Srianand, R.; Murphy, M. T.; Petitjean, P.; Agafonova, I. I.; D'Odorico, S.; Evans, T. M.; Levshakov, S. A.; Lopez, S.; Martins, C. J. A. P.; Reimers, D.; Vladilo, G.

    2014-01-01

    Absorption-line systems detected in high resolution quasar spectra can be used to compare the value of dimensionless fundamental constants such as the fine-structure constant, α, and the proton-to-electron mass ratio, μ = m_p/m_e, as measured in remote regions of the Universe to their value today on Earth. In recent years, some evidence has emerged of small temporal and also spatial variations in α on cosmological scales which may reach a fractional level of ≈ 10 ppm (parts per million). We are conducting a Large Programme of observations with the Very Large Telescope's Ultraviolet and Visual Echelle Spectrograph (UVES), and are obtaining high-resolution ({R ≈ 60 000}) and high signal-to-noise ratio (S/N ≈ 100) spectra calibrated specifically to study the variations of the fundamental constants. We here provide a general overview of the Large Programme and report on the first results for these two constants, discussed in detail in Molaro et al. (2013) and Rahmani et al. (2013). A stringent bound for Δα/α is obtained for the absorber at z_abs = 1.6919 towards HE 2217-2818. The absorption profile is complex with several very narrow features, and is modeled with 32 velocity components. The relative variation in α in this system is +1.3± 2.4_stat ± 1.0_sys ppm if Al II λ 1670 Å and three Fe II transitions are used, and +1.1 ± 2.6_stat ppm in a slightly different analysis with only Fe II transitions used. This is one of the tightest bounds on α-variation from an individual absorber and reveals no evidence for variation in α at the 3-ppm precision level (1σ confidence). The expectation at this sky position of the recently-reported dipolar variation of α is (3.2-5.4)±1.7 ppm depending on dipole model used and this constraint of Δα/α at face value is not supporting this expectation but not inconsistent with it at the 3σ level. For the proton-to-electron mass ratio the analysis of the H_2 absorption lines of the z_abs ≈ 2.4018 damped Lyα system

  8. Vicinal fluorine-fluorine coupling constants: Fourier analysis

    NASA Astrophysics Data System (ADS)

    San Fabián, J.; Westra Hoekzema, A. J. A.

    2004-10-01

    Stereochemical dependences of vicinal fluorine-fluorine nuclear magnetic resonance coupling constants (3JFF) have been studied with the multiconfigurational self-consistent field in the restricted active space approach, with the second-order polarization propagator approximation (SOPPA), and with density functional theory. The SOPPA results show the best overall agreement with experimental couplings. The relationship with the dihedral angle between the coupled fluorines has been studied by Fourier analysis, the result is very different from that of proton-proton couplings. The Fourier coefficients do not resemble those of a typical Karplus equation. The four nonrelativistic contributions to the coupling constants of 1,2-difluoroethane configurations have been studied separately showing that up to six Fourier coefficients are required to reproduce the calculated values satisfactorily. Comparison with Fourier coefficients for matching hydrogen fluoride dimer configurations suggests that the higher order Fourier coefficients (Cn⩾3) originate mainly from through-space Fermi contact interaction. The through-space interaction is the main reason 3JFF do not follow the Karplus equation.

  9. Modified large number theory with constant G

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

    Recami, E.

    1983-03-01

    The inspiring ''numerology'' uncovered by Dirac, Eddington, Weyl, et al. can be explained and derived when it is slightly modified so to connect the ''gravitational world'' (cosmos) with the ''strong world'' (hadron), rather than with the electromagnetic one. The aim of this note is to show the following. In the present approach to the ''Large Number Theory,'' cosmos and hadrons are considered to be (finite) similar systems, so that the ratio R-bar/r-bar of the cosmos typical length R-bar to the hadron typical length r-bar is constant in time (for instance, if both cosmos and hadrons undergo an expansion/contraction cycle: accordingmore » to the ''cyclical big-bang'' hypothesis: then R-bar and r-bar can be chosen to be the maximum radii, or the average radii). As a consequence, then gravitational constant G results to be independent of time. The present note is based on work done in collaboration with P.Caldirola, G. D. Maccarrone, and M. Pavsic.« less

  10. Simple liquid models with corrected dielectric constants

    PubMed Central

    Fennell, Christopher J.; Li, Libo; Dill, Ken A.

    2012-01-01

    Molecular simulations often use explicit-solvent models. Sometimes explicit-solvent models can give inaccurate values for basic liquid properties, such as the density, heat capacity, and permittivity, as well as inaccurate values for molecular transfer free energies. Such errors have motivated the development of more complex solvents, such as polarizable models. We describe an alternative here. We give new fixed-charge models of solvents for molecular simulations – water, carbon tetrachloride, chloroform and dichloromethane. Normally, such solvent models are parameterized to agree with experimental values of the neat liquid density and enthalpy of vaporization. Here, in addition to those properties, our parameters are chosen to give the correct dielectric constant. We find that these new parameterizations also happen to give better values for other properties, such as the self-diffusion coefficient. We believe that parameterizing fixed-charge solvent models to fit experimental dielectric constants may provide better and more efficient ways to treat solvents in computer simulations. PMID:22397577

  11. Rate constant for the reaction of atomic chlorine with methane

    NASA Technical Reports Server (NTRS)

    Lin, C. L.; Leu, M. T.; Demore, W. B.

    1978-01-01

    The rate constant and temperature dependence of the Cl + CH4 reaction have been investigated by the techniques of competitive chlorination of CH4/C2H6 mixtures and by discharge-flow/mass spectroscopy. The objectives were to determine an accurate value for the rate constant for use in stratospheric modeling, and to clarify discrepancies in results previously obtained by different techniques. The results deduced from the competitive chlorination study are in good agreement with the absolute values measured by the mass spectrometric method, and at temperatures above 300 K are in good agreement with measurements by other techniques based on resonance fluorescence detection of atomic chlorine. However, in the 220-300 K region, the competitive experiments indicate lower rate constants than those obtained by resonance fluorescence methods, and do not reproduce the curved Arrhenius plots seen in some of those studies.

  12. Indirect NMR spin-spin coupling constants in diatomic alkali halides

    NASA Astrophysics Data System (ADS)

    Jaszuński, Michał; Antušek, Andrej; Demissie, Taye B.; Komorovsky, Stanislav; Repisky, Michal; Ruud, Kenneth

    2016-12-01

    We report the Nuclear Magnetic Resonance (NMR) spin-spin coupling constants for diatomic alkali halides MX, where M = Li, Na, K, Rb, or Cs and X = F, Cl, Br, or I. The coupling constants are determined by supplementing the non-relativistic coupled-cluster singles-and-doubles (CCSD) values with relativistic corrections evaluated at the four-component density-functional theory (DFT) level. These corrections are calculated as the differences between relativistic and non-relativistic values determined using the PBE0 functional with 50% exact-exchange admixture. The total coupling constants obtained in this approach are in much better agreement with experiment than the standard relativistic DFT values with 25% exact-exchange, and are also noticeably better than the relativistic PBE0 results obtained with 50% exact-exchange. Further improvement is achieved by adding rovibrational corrections, estimated using literature data.

  13. Optimized constants for an ultraviolet light-adjustable intraocular lens.

    PubMed

    Conrad-Hengerer, Ina; Dick, H Burkhard; Hütz, Werner W; Haigis, Wolfgang; Hengerer, Fritz H

    2011-12-01

    To determine the accuracy of intraocular lens (IOL) power calculations and to suggest adjusted constants for implantation of ultraviolet light-adjustable IOLs. Center for Vision Science, Ruhr University Eye Clinic, Bochum, Germany. Cohort study. Eyes with a visually significant cataract that had phacoemulsification with implantation of a light-adjustable IOL were evaluated. IOLMaster measurements were performed before phacoemulsification and IOL implantation and 4 weeks after surgery before the first adjustment of the IOL. The difference in the expected refraction and estimation error was studied. The study evaluated 125 eyes. Using the surgical constants provided by the manufacturer of the light-adjustable IOL, the SRK/T formula gave a more hyperopic refraction than the Hoffer Q and Holladay 1 formulas. The mean error of prediction was 0.93 diopter (D) ± 0.69 (SD), 0.91 ± 0.63 D, and 0.86 ± 0.65 D, respectively. The corresponding mean absolute error of prediction was 0.98 ± 0.61 D, 0.93 ± 0.61 D, and 0.90 ± 0.59 D, respectively. With optimized constants for the formulas, the mean error of prediction was 0.00 ± 0.63 D for Hoffer Q, 0.00 ± 0.64 D for Holladay 1, and 0.00 ± 0.66 D for SRK/T. The expected refraction after phacoemulsification and implantation of a light-adjustable IOL toward the hyperopic side of the desired refraction could be considered when using the optimized constants for all formulas. Copyright © 2011 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  14. Modeling a constant power load for nickel-hydrogen battery testing using SPICE

    NASA Technical Reports Server (NTRS)

    Bearden, Douglas B.; Lollar, Louis F.; Nelms, R. M.

    1990-01-01

    The effort to design and model a constant power load for the HST (Hubble Space Telescope) nickel-hydrogen battery tests is described. The constant power load was designed for three different simulations on the batteries: life cycling, reconditioning, and capacity testing. A dc-dc boost converter was designed to act as this constant power load. A boost converter design was chosen because of the low test battery voltage (4 to 6 VDC) generated and the relatively high power requirement of 60 to 70 W. The SPICE model was shown to consistently predict variations in the actual circuit as various designs were attempted. It is concluded that the confidence established in the SPICE model of the constant power load ensures its extensive utilization in future efforts to improve performance in the actual load circuit.

  15. 50 CFR 648.10 - VMS and DAS requirements for vessel owners/operators.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 12 2013-10-01 2013-10-01 false VMS and DAS requirements for vessel owners/operators. 648.10 Section 648.10 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE FISHERIES OF THE NORTHEASTERN...

  16. Functionalised graphene sheets as effective high dielectric constant fillers

    NASA Astrophysics Data System (ADS)

    Romasanta, Laura J.; Hernández, Marianella; López-Manchado, Miguel A.; Verdejo, Raquel

    2011-08-01

    A new functionalised graphene sheet (FGS) filled poly(dimethyl)siloxane insulator nanocomposite has been developed with high dielectric constant, making it well suited for applications in flexible electronics. The dielectric permittivity increased tenfold at 10 Hz and 2 wt.% FGS, while preserving low dielectric losses and good mechanical properties. The presence of functional groups on the graphene sheet surface improved the compatibility nanofiller/polymer at the interface, reducing the polarisation process. This study demonstrates that functionalised graphene sheets are ideal nanofillers for the development of new polymer composites with high dielectric constant values. PACS: 78.20.Ci, 72.80.Tm, 62.23.Kn

  17. Role of dielectric constant in electrohydrodynamics of conducting fluids

    NASA Technical Reports Server (NTRS)

    Rhodes, Percy H.; Snyder, Robert S.; Roberts, Glyn O.

    1994-01-01

    Electrohydrodynamic sample distortion during continuous flow electrophoresis is an experiment to be conducted during the second International Microgravity Laboratory (IML-2) in July 1994. The specific objective of this experiment is the distortion caused by the difference in dielectric constant between the sample and surrounding buffer. Although the role of sample conductivity in electrohydrodynamic has been the subject of both flight and ground experiments, the separate role of dielectric constant, independent of sample conductivity, has not been measured. This paper describes some of the laboratory research and model development that will support the flight experiment on IML-2.

  18. Topological quantization in units of the fine structure constant.

    PubMed

    Maciejko, Joseph; Qi, Xiao-Liang; Drew, H Dennis; Zhang, Shou-Cheng

    2010-10-15

    Fundamental topological phenomena in condensed matter physics are associated with a quantized electromagnetic response in units of fundamental constants. Recently, it has been predicted theoretically that the time-reversal invariant topological insulator in three dimensions exhibits a topological magnetoelectric effect quantized in units of the fine structure constant α=e²/ℏc. In this Letter, we propose an optical experiment to directly measure this topological quantization phenomenon, independent of material details. Our proposal also provides a way to measure the half-quantized Hall conductances on the two surfaces of the topological insulator independently of each other.

  19. Nonlocal conservation laws of the constant astigmatism equation

    NASA Astrophysics Data System (ADS)

    Hlaváč, Adam; Marvan, Michal

    2017-03-01

    For the constant astigmatism equation, we construct a system of nonlocal conservation laws (an abelian covering) closed under the reciprocal transformations. The corresponding potentials are functionally independent modulo a Wronskian type relation.

  20. 18 CFR 806.12 - Constant-rate aquifer testing.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... withdraw or increase a withdrawal of groundwater shall perform a constant-rate aquifer test in accordance... groundwater availability analysis to determine the availability of water during a 1-in-10-year recurrence...

  1. 18 CFR 806.12 - Constant-rate aquifer testing.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... withdraw or increase a withdrawal of groundwater shall perform a constant-rate aquifer test in accordance... groundwater availability analysis to determine the availability of water during a 1-in-10-year recurrence...

  2. 18 CFR 806.12 - Constant-rate aquifer testing.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... withdraw or increase a withdrawal of groundwater shall perform a constant-rate aquifer test in accordance... groundwater availability analysis to determine the availability of water during a 1-in-10-year recurrence...

  3. 18 CFR 806.12 - Constant-rate aquifer testing.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... withdraw or increase a withdrawal of groundwater shall perform a constant-rate aquifer test in accordance... groundwater availability analysis to determine the availability of water during a 1-in-10-year recurrence...

  4. Constant-frequency, clamped-mode resonant converters

    NASA Technical Reports Server (NTRS)

    Tsai, Fu-Sheng; Materu, Peter; Lee, Fred C.

    1987-01-01

    Two novel clamped-mode resonant converters are proposed which operate at a constant frequency while retaining many desired features of conventional series- and parallel-resonant converters. State-plane analysis techniques are used to identify all possible operating modes and define their mode boundaries. Control-to-output characteristics are derived that specify the regions for natural and forced commutation. The predicted operating modes are verified using a prototype circuit.

  5. Phase Velocity and Full-Waveform Analysis of Co-located Distributed Acoustic Sensing (DAS) Channels and Geophone Sensor

    NASA Astrophysics Data System (ADS)

    Parker, L.; Mellors, R. J.; Thurber, C. H.; Wang, H. F.; Zeng, X.

    2015-12-01

    A 762-meter Distributed Acoustic Sensing (DAS) array with a channel spacing of one meter was deployed at the Garner Valley Downhole Array in Southern California. The array was approximately rectangular with dimensions of 180 meters by 80 meters. The array also included two subdiagonals within the rectangle along which three-component geophones were co-located. Several active sources were deployed, including a 45-kN, swept-frequency, shear-mass shaker, which produced strong Rayleigh waves across the array. Both DAS and geophone traces were filtered in 2-Hz steps between 4 and 20 Hz to obtain phase velocities as a function of frequency from fitting the moveout of travel times over distances of 35 meters or longer. As an alternative to this traditional means of finding phase velocity, it is theoretically possible to find the Rayleigh-wave phase velocity at each point of co-location as the ratio of DAS and geophone responses, because DAS is sensitive to ground strain and geophones are sensitive to ground velocity, after suitable corrections for instrument response (Mikumo & Aki, 1964). The concept was tested in WPP, a seismic wave propagation program, by first validating and then using a 3D synthetic, full-waveform seismic model to simulate the effect of increased levels of noise and uncertainty as data go from ideal to more realistic. The results obtained from this study provide a better understanding of the DAS response and its potential for being combined with traditional seismometers for obtaining phase velocity at a single location. This analysis is part of the PoroTomo project (Poroelastic Tomography by Adjoint Inverse Modeling of Data from Seismology, Geodesy, and Hydrology, http://geoscience.wisc.edu/feigl/porotomo).

  6. The effects of rigid motions on elastic network model force constants

    PubMed Central

    Lezon, Timothy R.

    2012-01-01

    Elastic network models provide an efficient way to quickly calculate protein global dynamics from experimentally determined structures. The model’s single parameter, its force constant, determines the physical extent of equilibrium fluctuations. The values of force constants can be calculated by fitting to experimental data, but the results depend on the type of experimental data used. Here we investigate the differences between calculated values of force constants _t to data from NMR and X-ray structures. We find that X-ray B factors carry the signature of rigid-body motions, to the extent that B factors can be almost entirely accounted for by rigid motions alone. When fitting to more refined anisotropic temperature factors, the contributions of rigid motions are significantly reduced, indicating that the large contribution of rigid motions to B factors is a result of over-fitting. No correlation is found between force constants fit to NMR data and those fit to X-ray data, possibly due to the inability of NMR data to accurately capture protein dynamics. PMID:22228562

  7. The effects of rigid motions on elastic network model force constants.

    PubMed

    Lezon, Timothy R

    2012-04-01

    Elastic network models provide an efficient way to quickly calculate protein global dynamics from experimentally determined structures. The model's single parameter, its force constant, determines the physical extent of equilibrium fluctuations. The values of force constants can be calculated by fitting to experimental data, but the results depend on the type of experimental data used. Here, we investigate the differences between calculated values of force constants and data from NMR and X-ray structures. We find that X-ray B factors carry the signature of rigid-body motions, to the extent that B factors can be almost entirely accounted for by rigid motions alone. When fitting to more refined anisotropic temperature factors, the contributions of rigid motions are significantly reduced, indicating that the large contribution of rigid motions to B factors is a result of over-fitting. No correlation is found between force constants fit to NMR data and those fit to X-ray data, possibly due to the inability of NMR data to accurately capture protein dynamics. Copyright © 2011 Wiley Periodicals, Inc.

  8. Long-Term Efficacy of Constant Current Deep Brain Stimulation in Essential Tremor.

    PubMed

    Rezaei Haddad, Ali; Samuel, Michael; Hulse, Natasha; Lin, Hsin-Ying; Ashkan, Keyoumars

    2017-07-01

    Ventralis intermedius deep brain stimulation is an established intervention for medication-refractory essential tremor. Newer constant current stimulation technology offers theoretical advantage over the traditional constant voltage systems in terms of delivering a more biologically stable therapy. There are no previous reports on the outcomes of constant current deep brain stimulation in the treatment of essential tremor. This study aimed to evaluate the long-term efficacy of ventralis intermedius constant current deep brain stimulation in patients diagnosed with essential tremor. Essential tremor patients implanted with constant current deep brain stimulation for a minimum of three years were evaluated. Clinical outcomes were assessed using the Fahn-Tolosa-Marin tremor rating scale at baseline and postoperatively at the time of evaluation. The quality of life in the patients was assessed using the Quality of Life in Essential Tremor questionnaire. Ten patients were evaluated with a median age at evaluation of 74 years (range 66-79) and a mean follow up time of 49.7 (range 36-78) months since starting stimulation. Constant current ventralis intermedius deep brain stimulation was well tolerated and effective in all patients with a mean score improvement from 50.7 ± 5.9 to 17.4 ± 5.7 (p = 0.0020) in the total Fahn-Tolosa-Marin rating scale score (65.6%). Furthermore, the total combined mean Quality of Life in Essential Tremor score was improved from 56.2 ± 4.9 to 16.8 ± 3.5 (p value = 0.0059) (70.1%). This report shows that long-term constant current ventralis intermedius deep brain stimulation is a safe and effective intervention for essential tremor patients. © 2017 International Neuromodulation Society.

  9. An equivalent method of mixed dielectric constant in passive microwave/millimeter radiometric measurement

    NASA Astrophysics Data System (ADS)

    Su, Jinlong; Tian, Yan; Hu, Fei; Gui, Liangqi; Cheng, Yayun; Peng, Xiaohui

    2017-10-01

    Dielectric constant is an important role to describe the properties of matter. This paper proposes This paper proposes the concept of mixed dielectric constant(MDC) in passive microwave radiometric measurement. In addition, a MDC inversion method is come up, Ratio of Angle-Polarization Difference(RAPD) is utilized in this method. The MDC of several materials are investigated using RAPD. Brightness temperatures(TBs) which calculated by MDC and original dielectric constant are compared. Random errors are added to the simulation to test the robustness of the algorithm. Keywords: Passive detection, microwave/millimeter, radiometric measurement, ratio of angle-polarization difference (RAPD), mixed dielectric constant (MDC), brightness temperatures, remote sensing, target recognition.

  10. The impact of constant light on the estrous cycle of the rat.

    PubMed

    Campbell, C S; Schwartz, N B

    1980-04-01

    The initial effects of constant bright light on the events of the rat estrous cycle were monitored in order to examine the interdependence of the hormonal and behavioral rhythms which comprise the cycle. Females exposed to constant bright light for only one cycle either failed to ovulate or showed a delay in the hormonal and behavioral events of the cycle as well as in ovulation. Females exposed to constant light for two cycles 1) failed to ovulate, 2) showed an advancement, or 3) showed a delay in the hormonal events of the estrous cycle and ovulation. Vaginal cytology and the onset of locomotor activity did not maintain their normal temporal relationships with the other events of the estrous cycle in constant light. In spite of the absence of an external timing signal, the majority of hormonal rhythms maintained their normal phase relationships and showed little sign of internal desynchrony. Ovaries in many animals showed high rates of follicular atresia early in the cycle, suggesting that the effects of bright constant light are far more complex than can be attributed to a simple absence of an external timing signal.

  11. Some relations among engineering constants of wood

    Treesearch

    Jen Y. Liu; Robert J. Ross

    1998-01-01

    Wood may be described as an orthotropic material with unique and independent mechanical properties in the directions of three mutually perpendicular axes– longitudinal ( L ), radial ( R ), and tangential (T ). These mechanical properties are also called engineering constants. Orthotropic materials are of special relevance to composite materials. Therefore, mathematical...

  12. Hubble Space Telescope secondary mirror vertex radius/conic constant test

    NASA Technical Reports Server (NTRS)

    Parks, Robert

    1991-01-01

    The Hubble Space Telescope backup secondary mirror was tested to determine the vertex radius and conic constant. Three completely independent tests (to the same procedure) were performed. Similar measurements in the three tests were highly consistent. The values obtained for the vertex radius and conic constant were the nominal design values within the error bars associated with the tests. Visual examination of the interferometric data did not show any measurable zonal figure error in the secondary mirror.

  13. Effect of material constants on power output in piezoelectric vibration-based generators.

    PubMed

    Takeda, Hiroaki; Mihara, Kensuke; Yoshimura, Tomohiro; Hoshina, Takuya; Tsurumi, Takaaki

    2011-09-01

    A possible power output estimation based on material constants in piezoelectric vibration-based generators is proposed. A modified equivalent circuit model of the generator was built and was validated by the measurement results in the generator fabricated using potassium sodium niobate-based and lead zirconate titanate (PZT) ceramics. Subsequently, generators with the same structure using other PZT-based and bismuth-layered structure ferroelectrics ceramics were fabricated and tested. The power outputs of these generators were expressed as a linear functions of the term composed of electromechanical coupling coefficients k(sys)(2) and mechanical quality factors Q*(m) of the generator. The relationship between device constants (k(sys)(2) and Q*(m)) and material constants (k(31)(2) and Q(m)) was clarified. Estimation of the power output using material constants is demonstrated and the appropriate piezoelectric material for the generator is suggested.

  14. Gravitational lensing effects in a time-variable cosmological 'constant' cosmology

    NASA Technical Reports Server (NTRS)

    Ratra, Bharat; Quillen, Alice

    1992-01-01

    A scalar field phi with a potential V(phi) varies as phi exp -alpha(alpha is greater than 0) has an energy density, behaving like that of a time-variable cosmological 'constant', that redshifts less rapidly than the energy densities of radiation and matter, and so might contribute significantly to the present energy density. We compute, in this spatially flat cosmology, the gravitational lensing optical depth, and the expected lens redshift distribution for fixed source redshift. We find, for the values of alpha of about 4 and baryonic density parameter Omega of about 0.2 consistent with the classical cosmological tests, that the optical depth is significantly smaller than that in a constant-Lambda model with the same Omega. We also find that the redshift of the maximum of the lens distribution falls between that in the constant-Lambda model and that in the Einstein-de Sitter model.

  15. Variable energy constant current accelerator structure

    DOEpatents

    Anderson, Oscar A.

    1990-01-01

    A variable energy, constant current ion beam accelerator structure is disclosed comprising an ion source capable of providing the desired ions, a pre-accelerator for establishing an initial energy level, a matching/pumping module having means for focusing means for maintaining the beam current, and at least one main accelerator module for continuing beam focus, with means capable of variably imparting acceleration to the beam so that a constant beam output current is maintained independent of the variable output energy. In a preferred embodiment, quadrupole electrodes are provided in both the matching/pumping module and the one or more accelerator modules, and are formed using four opposing cylinder electrodes which extend parallel to the beam axis and are spaced around the beam at 90.degree. intervals with opposing electrodes maintained at the same potential. Adjacent cylinder electrodes of the quadrupole structure are maintained at different potentials to thereby reshape the cross section of the charged particle beam to an ellipse in cross section at the mid point along each quadrupole electrode unit in the accelerator modules. The beam is maintained in focus by alternating the major axis of the ellipse along the x and y axis respectively at adjacent quadrupoles. In another embodiment, electrostatic ring electrodes may be utilized instead of the quadrupole electrodes.

  16. Bioclimatic Thresholds, Thermal Constants and Survival of Mealybug, Phenacoccus solenopsis (Hemiptera: Pseudococcidae) in Response to Constant Temperatures on Hibiscus

    PubMed Central

    Sreedevi, Gudapati; Prasad, Yenumula Gerard; Prabhakar, Mathyam; Rao, Gubbala Ramachandra; Vennila, Sengottaiyan; Venkateswarlu, Bandi

    2013-01-01

    Temperature-driven development and survival rates of the mealybug, Phenacoccussolenopsis Tinsley (Hemiptera: Pseudococcidae) were examined at nine constant temperatures (15, 20, 25, 27, 30, 32, 35 and 40°C) on hibiscus ( Hibiscus rosa -sinensis L.). Crawlers successfully completed development to adult stage between 15 and 35°C, although their survival was affected at low temperatures. Two linear and four nonlinear models were fitted to describe developmental rates of P . solenopsis as a function of temperature, and for estimating thermal constants and bioclimatic thresholds (lower, optimum and upper temperature thresholds for development: Tmin, Topt and Tmax, respectively). Estimated thresholds between the two linear models were statistically similar. Ikemoto and Takai’s linear model permitted testing the equivalence of lower developmental thresholds for life stages of P . solenopsis reared on two hosts, hibiscus and cotton. Thermal constants required for completion of cumulative development of female and male nymphs and for the whole generation were significantly lower on hibiscus (222.2, 237.0, 308.6 degree-days, respectively) compared to cotton. Three nonlinear models performed better in describing the developmental rate for immature instars and cumulative life stages of female and male and for generation based on goodness-of-fit criteria. The simplified β type distribution function estimated Topt values closer to the observed maximum rates. Thermodynamic SSI model indicated no significant differences in the intrinsic optimum temperature estimates for different geographical populations of P . solenopsis . The estimated bioclimatic thresholds and the observed survival rates of P . solenopsis indicate the species to be high-temperature adaptive, and explained the field abundance of P . solenopsis on its host plants. PMID:24086597

  17. Response of the human vestibulo-ocular reflex system to constant angular acceleration. I. Theoretical study.

    PubMed

    Boumans, L J; Rodenburg, M; Maas, A J

    1983-01-01

    The response of the human vestibulo-ocular reflex system to a constant angular acceleration is calculated using a second order model with an adaptation term. After first reaching a maximum the peracceleratory response declines. When the stimulus duration is long the decay is mainly governed by the adaptation time constant Ta, which enables to reliably estimate this time constant. In the postacceleratory period of constant velocity there is a reversal in response. The magnitude and the time course of the per- and postacceleratory response are calculated for various values of the cupular time constant T1, the adaptation time constant Ta, and the stimulus duration, thus enabling their influence to be assessed.

  18. Galaxy Formation Efficiency and the Multiverse Explanation of the Cosmological Constant with EAGLE Simulations

    NASA Astrophysics Data System (ADS)

    Barnes, Luke A.; Elahi, Pascal J.; Salcido, Jaime; Bower, Richard G.; Lewis, Geraint F.; Theuns, Tom; Schaller, Matthieu; Crain, Robert A.; Schaye, Joop

    2018-04-01

    Models of the very early universe, including inflationary models, are argued to produce varying universe domains with different values of fundamental constants and cosmic parameters. Using the cosmological hydrodynamical simulation code from the EAGLE collaboration, we investigate the effect of the cosmological constant on the formation of galaxies and stars. We simulate universes with values of the cosmological constant ranging from Λ = 0 to Λ0 × 300, where Λ0 is the value of the cosmological constant in our Universe. Because the global star formation rate in our Universe peaks at t = 3.5 Gyr, before the onset of accelerating expansion, increases in Λ of even an order of magnitude have only a small effect on the star formation history and efficiency of the universe. We use our simulations to predict the observed value of the cosmological constant, given a measure of the multiverse. Whether the cosmological constant is successfully predicted depends crucially on the measure. The impact of the cosmological constant on the formation of structure in the universe does not seem to be a sharp enough function of Λ to explain its observed value alone.

  19. Galaxy formation efficiency and the multiverse explanation of the cosmological constant with EAGLE simulations

    NASA Astrophysics Data System (ADS)

    Barnes, Luke A.; Elahi, Pascal J.; Salcido, Jaime; Bower, Richard G.; Lewis, Geraint F.; Theuns, Tom; Schaller, Matthieu; Crain, Robert A.; Schaye, Joop

    2018-07-01

    Models of the very early Universe, including inflationary models, are argued to produce varying universe domains with different values of fundamental constants and cosmic parameters. Using the cosmological hydrodynamical simulation code from the EAGLE collaboration, we investigate the effect of the cosmological constant on the formation of galaxies and stars. We simulate universes with values of the cosmological constant ranging from Λ = 0 to Λ0 × 300, where Λ0 is the value of the cosmological constant in our Universe. Because the global star formation rate in our Universe peaks at t = 3.5 Gyr, before the onset of accelerating expansion, increases in Λ of even an order of magnitude have only a small effect on the star formation history and efficiency of the universe. We use our simulations to predict the observed value of the cosmological constant, given a measure of the multiverse. Whether the cosmological constant is successfully predicted depends crucially on the measure. The impact of the cosmological constant on the formation of structure in the universe does not seem to be a sharp enough function of Λ to explain its observed value alone.

  20. Constant-Elasticity-of-Substitution Simulation

    NASA Technical Reports Server (NTRS)

    Reiter, G.

    1986-01-01

    Program simulates constant elasticity-of-substitution (CES) production function. CES function used by economic analysts to examine production costs as well as uncertainties in production. User provides such input parameters as price of labor, price of capital, and dispersion levels. CES minimizes expected cost to produce capital-uncertainty pair. By varying capital-value input, one obtains series of capital-uncertainty pairs. Capital-uncertainty pairs then used to generate several cost curves. CES program menu driven and features specific print menu for examining selected output curves. Program written in BASIC for interactive execution and implemented on IBM PC-series computer.

  1. Event DAS-444Ø6-6 soybean grown in Brazil is compositionally equivalent to non-transgenic soybean.

    PubMed

    Fast, Brandon J; Galan, Maria P; Schafer, Ariane C

    2016-04-02

    Soybean event DAS-444Ø6-6 is tolerant to the herbicides 2,4-D, glyphosate, and glufosinate. An investigation of potential unintended adverse compositional changes in a genetically modified crop is required to meet government regulatory requirements in various geographies. A study to meet these requirements in Brazil was completed demonstrating compositional equivalency between DAS-444Ø6-6 and non-transgenic soybean. This study supplements the extensive literature supporting transgenesis as less disruptive of crop composition compared with traditional breeding methods.

  2. Protein dielectric constants determined from NMR chemical shift perturbations.

    PubMed

    Kukic, Predrag; Farrell, Damien; McIntosh, Lawrence P; García-Moreno E, Bertrand; Jensen, Kristine Steen; Toleikis, Zigmantas; Teilum, Kaare; Nielsen, Jens Erik

    2013-11-13

    Understanding the connection between protein structure and function requires a quantitative understanding of electrostatic effects. Structure-based electrostatic calculations are essential for this purpose, but their use has been limited by a long-standing discussion on which value to use for the dielectric constants (ε(eff) and ε(p)) required in Coulombic and Poisson-Boltzmann models. The currently used values for ε(eff) and ε(p) are essentially empirical parameters calibrated against thermodynamic properties that are indirect measurements of protein electric fields. We determine optimal values for ε(eff) and ε(p) by measuring protein electric fields in solution using direct detection of NMR chemical shift perturbations (CSPs). We measured CSPs in 14 proteins to get a broad and general characterization of electric fields. Coulomb's law reproduces the measured CSPs optimally with a protein dielectric constant (ε(eff)) from 3 to 13, with an optimal value across all proteins of 6.5. However, when the water-protein interface is treated with finite difference Poisson-Boltzmann calculations, the optimal protein dielectric constant (ε(p)) ranged from 2 to 5 with an optimum of 3. It is striking how similar this value is to the dielectric constant of 2-4 measured for protein powders and how different it is from the ε(p) of 6-20 used in models based on the Poisson-Boltzmann equation when calculating thermodynamic parameters. Because the value of ε(p) = 3 is obtained by analysis of NMR chemical shift perturbations instead of thermodynamic parameters such as pK(a) values, it is likely to describe only the electric field and thus represent a more general, intrinsic, and transferable ε(p) common to most folded proteins.

  3. Unified Technical Concepts. Module 12: Time Constants.

    ERIC Educational Resources Information Center

    Technical Education Research Center, Waco, TX.

    This concept module on time constants is one of thirteen modules that provide a flexible, laboratory-based physics instructional package designed to meet the specialized needs of students in two-year, postsecondary technical schools. Each of the thirteen concept modules discusses a single physics concept and how it is applied to each energy…

  4. a Measurement of the Fine Structure Constant

    NASA Astrophysics Data System (ADS)

    Hensley, Joel M.; Wicht, Andreas; Sarajlic, Edina; Chu, Steven

    2002-06-01

    Using an atom interferometer method, we measure the recoil velocity of cesium due to the coherent scattering of a photon. This measurement is used to obtain a preliminary value of ħ/MCs and the fine structure constant, α, with an uncertainty Δα/α = 7.3 × 10-9.

  5. Unitaxial constant velocity microactuator

    DOEpatents

    McIntyre, Timothy J.

    1994-01-01

    A uniaxial drive system or microactuator capable of operating in an ultra-high vacuum environment. The mechanism includes a flexible coupling having a bore therethrough, and two clamp/pusher assemblies mounted in axial ends of the coupling. The clamp/pusher assemblies are energized by voltage-operated piezoelectrics therewithin to operatively engage the shaft and coupling causing the shaft to move along its rotational axis through the bore. The microactuator is capable of repeatably positioning to sub-manometer accuracy while affording a scan range in excess of 5 centimeters. Moreover, the microactuator generates smooth, constant velocity motion profiles while producing a drive thrust of greater than 10 pounds. The system is remotely controlled and piezoelectrically driven, hence minimal thermal loading, vibrational excitation, or outgassing is introduced to the operating environment.

  6. Electronic transport in two-dimensional high dielectric constant nanosystems

    DOE PAGES

    Ortuño, M.; Somoza, A. M.; Vinokur, V. M.; ...

    2015-04-10

    There has been remarkable recent progress in engineering high-dielectric constant two dimensional (2D) materials, which are being actively pursued for applications in nanoelectronics in capacitor and memory devices, energy storage, and high-frequency modulation in communication devices. Yet many of the unique properties of these systems are poorly understood and remain unexplored. Here we report a numerical study of hopping conductivity of the lateral network of capacitors, which models two-dimensional insulators, and demonstrate that 2D long-range Coulomb interactions lead to peculiar size effects. We find that the characteristic energy governing electronic transport scales logarithmically with either system size or electrostatic screeningmore » length depending on which one is shorter. Our results are relevant well beyond their immediate context, explaining, for example, recent experimental observations of logarithmic size dependence of electric conductivity of thin superconducting films in the critical vicinity of superconductor-insulator transition where a giant dielectric constant develops. Our findings mark a radical departure from the orthodox view of conductivity in 2D systems as a local characteristic of materials and establish its macroscopic global character as a generic property of high-dielectric constant 2D nanomaterials.« less

  7. Electronic transport in two-dimensional high dielectric constant nanosystems.

    PubMed

    Ortuño, M; Somoza, A M; Vinokur, V M; Baturina, T I

    2015-04-10

    There has been remarkable recent progress in engineering high-dielectric constant two dimensional (2D) materials, which are being actively pursued for applications in nanoelectronics in capacitor and memory devices, energy storage, and high-frequency modulation in communication devices. Yet many of the unique properties of these systems are poorly understood and remain unexplored. Here we report a numerical study of hopping conductivity of the lateral network of capacitors, which models two-dimensional insulators, and demonstrate that 2D long-range Coulomb interactions lead to peculiar size effects. We find that the characteristic energy governing electronic transport scales logarithmically with either system size or electrostatic screening length depending on which one is shorter. Our results are relevant well beyond their immediate context, explaining, for example, recent experimental observations of logarithmic size dependence of electric conductivity of thin superconducting films in the critical vicinity of superconductor-insulator transition where a giant dielectric constant develops. Our findings mark a radical departure from the orthodox view of conductivity in 2D systems as a local characteristic of materials and establish its macroscopic global character as a generic property of high-dielectric constant 2D nanomaterials.

  8. Differential Mobility Spectrometry: Preliminary Findings on Determination of Fundamental Constants

    NASA Technical Reports Server (NTRS)

    Limero, Thomas; Cheng, Patti; Boyd, John

    2007-01-01

    The electron capture detector (ECD) has been used for 40+ years (1) to derive fundamental constants such as a compound's electron affinity. Given this historical perspective, it is not surprising that differential mobility spectrometry (DMS) might be used in a like manner. This paper will present data from a gas chromatography (GC)-DMS instrument that illustrates the potential capability of this device to derive fundamental constants for electron-capturing compounds. Potential energy curves will be used to provide possible explanation of the data.

  9. Constant envelope OFDM scheme for 6PolSK-QPSK

    NASA Astrophysics Data System (ADS)

    Li, Yupeng; Ding, Ding

    2018-03-01

    A constant envelope OFDM scheme with phase modulator (PM-CE-OFDM) for 6PolSK-QPSK modulation was demonstrated. Performance under large fiber launch power is measured to check its advantages in counteracting fiber nonlinear impairments. In our simulation, PM-CE-OFDM, RF-assisted constant envelope OFDM (RF-CE-OFDM) and conventional OFDM (Con-OFDM) are transmitted through 80 km standard single mode fiber (SSMF) single channel and WDM system. Simulation results confirm that PM-CE-OFDM has best performance in resisting fiber nonlinearity. In addition, benefiting from the simple system structure, the complexity and cost of PM-CE-OFDM system could be reduced effectively.

  10. Flame Chemiluminescence Rate Constants for Quantitative Microgravity Combustion Diagnostics

    NASA Technical Reports Server (NTRS)

    Luque, Jorge; Smith, Gregory P.; Jeffries, Jay B.; Crosley, David R.; Weiland, Karen (Technical Monitor)

    2001-01-01

    Absolute excited state concentrations of OH(A), CH(A), and C2(d) were determined in three low pressure premixed methane-air flames. Two dimensional images of chemiluminescence from these states were recorded by a filtered CCD camera, processed by Abel inversion, and calibrated against Rayleigh scattering, Using a previously validated 1-D flame model with known chemistry and excited state quenching rate constants, rate constants are extracted for the reactions CH + O2 (goes to) OH(A) + CO and C2H + O (goes to) CH(A) + CO at flame temperatures. Variations of flame emission intensities with stoichiometry agree well with model predictions.

  11. Value of the Cosmological Constant in Emergent Quantum Gravity

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

    Hogan, Craig

    It is suggested that the exact value of the cosmological constant could be derived from first principles, based on entanglement of the Standard Model field vacuum with emergent holographic quantum geometry. For the observed value of the cosmological constant, geometrical information is shown to agree closely with the spatial information density of the QCD vacuum, estimated in a free-field approximation. The comparison is motivated by a model of exotic rotational fluctuations in the inertial frame that can be precisely tested in laboratory experiments. Cosmic acceleration in this model is always positive, but fluctuates with characteristic coherence lengthmore » $$\\approx 100$$km and bandwidth $$\\approx 3000$$ Hz.« less

  12. Functionalised graphene sheets as effective high dielectric constant fillers

    PubMed Central

    2011-01-01

    A new functionalised graphene sheet (FGS) filled poly(dimethyl)siloxane insulator nanocomposite has been developed with high dielectric constant, making it well suited for applications in flexible electronics. The dielectric permittivity increased tenfold at 10 Hz and 2 wt.% FGS, while preserving low dielectric losses and good mechanical properties. The presence of functional groups on the graphene sheet surface improved the compatibility nanofiller/polymer at the interface, reducing the polarisation process. This study demonstrates that functionalised graphene sheets are ideal nanofillers for the development of new polymer composites with high dielectric constant values. PACS: 78.20.Ci, 72.80.Tm, 62.23.Kn PMID:21867505

  13. Variations in the fine-structure constant constraining gravity theories

    NASA Astrophysics Data System (ADS)

    Bezerra, V. B.; Cunha, M. S.; Muniz, C. R.; Tahim, M. O.; Vieira, H. S.

    2016-08-01

    In this paper, we investigate how the fine-structure constant, α, locally varies in the presence of a static and spherically symmetric gravitational source. The procedure consists in calculating the solution and the energy eigenvalues of a massive scalar field around that source, considering the weak-field regime. From this result, we obtain expressions for a spatially variable fine-structure constant by considering suitable modifications in the involved parameters admitting some scenarios of semi-classical and quantum gravities. Constraints on free parameters of the approached theories are calculated from astrophysical observations of the emission spectra of a white dwarf. Such constraints are finally compared with those obtained in the literature.

  14. Critique of Coleman's Theory of the Vanishing Cosmological Constant

    NASA Astrophysics Data System (ADS)

    Susskind, Leonard

    In these lectures I would like to review some of the criticisms to the Coleman worm-hole theory of the vanishing cosmological constant. In particular, I would like to focus on the most fundamental assumption that the path integral over topologies defines a probability for the cosmological constant which has the form EXP(A) with A being the Baum-Hawking-Coleman saddle point. Coleman argues that the euclideam path integral over all geometries may be dominated by special configurations which consist of large smooth "spheres" connected by any number of narrow wormholes. Formally summing up such configurations gives a very divergent expression for the path integral…

  15. Constant scalar curvature hypersurfaces in (3 + 1) -dimensional GHMC Minkowski spacetimes

    NASA Astrophysics Data System (ADS)

    Smith, Graham

    2018-06-01

    We prove that every (3 + 1) -dimensional flat GHMC Minkowski spacetime which is not a translation spacetime or a Misner spacetime carries a unique foliation by spacelike hypersurfaces of constant scalar curvature. In other words, we prove that every such spacetime carries a unique time function with isochrones of constant scalar curvature. Furthermore, this time function is a smooth submersion.

  16. Algorithm for Calculating the Dissociation Constants of Ampholytes in Nonbuffer Systems

    NASA Astrophysics Data System (ADS)

    Lysova, S. S.; Skripnikova, T. A.; Zevatskii, Yu. E.

    2018-05-01

    An algorithm for calculating the dissociation constants of ampholytes in aqueous solutions is developed on the basis of spectrophotometric data in the UV and visible ranges without pH measurements of a medium and without buffer solutions. The proposed algorithm has been experimentally tested for five ampholytes of different strengths. The relative error of measuring dissociation constants is less than 5%.

  17. CONSTRAINTS ON SPATIAL VARIATIONS IN THE FINE-STRUCTURE CONSTANT FROM PLANCK

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

    O'Bryan, Jon; Smidt, Joseph; De Bernardis, Francesco

    2015-01-01

    We use the cosmic microwave background (CMB) anisotropy data from Planck to constrain the spatial fluctuations of the fine-structure constant α at a redshift of 1100. We use a quadratic estimator to measure the four-point correlation function of the CMB temperature anisotropies and extract the angular power spectrum fine-structure constant spatial variations projected along the line of sight at the last scattering surface. At tens of degree angular scales and above, we constrain the fractional rms fluctuations of the fine-structure constant to be (δα/α){sub rms} < 3.4 × 10{sup –3} at the 68% confidence level. We find no evidence formore » a spatially varying α at a redshift of 10{sup 3}.« less

  18. Hadron mass and decays constant predictions of the valence approximation to lattice QCD

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

    Weingarten, D.

    1993-05-01

    A key goal of the lattice formulation of QCD is to reproduce the masses and decay constants of the low-lying baryons and mesons. Lattice QCD mass and decay constant predictions for the real world are supposed to be obtained from masses and decay constants calculated with finite lattice spacing and finite lattice volume by taking the limits of zero spacing and infinite volume. In addition, since the algorithms used for hadron mass and decay constant calculations become progressively slower for small quark masses, results are presently found with quark masses much larger than the expected values of the up andmore » down quark masses. Predictions for the properties of hadrons containing up and down quarks then require a further extrapolation to small quark masses. The author reports here mass and decay constant predictions combining all three extrapolations for Wilson quarks in the valence (quenched) approximation. This approximation may be viewed as replacing the momentum and frequency dependent color dielectric constant arising from quark-antiquark vacuum polarization with its zero-momentum, zero-frequency limit. These calculations used approximately one year of machine time on the GF11 parallel computer running at a sustained rate of between 5 and 7 Gflops.« less

  19. Is the cosmological constant screened in Liouville gravity with matter?

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

    Inami, Takeo; Koyama, Yoji; Nakayama, Yu

    In this study, there has been a proposal that infrared quantum effects of massless interacting field theories in de Sitter space may provide time-dependent screening of the cosmological constant. As a concrete model of the proposal, we study the three loop corrections to the energy–momentum tensor of massless λΦ 4 theory in the background of classical Liouville gravity in D = 2 dimensional de Sitter space. We find that the cosmological constant is screened, in sharp contrast to the massless λΦ 4 theory in D = 4 dimensions due to the sign difference between the cosmological constant of the Liouvillemore » gravity and that of the Einstein gravity. To argue for the robustness of our prediction, we introduce the concept of time-dependent infrared counter-terms and examine if they recover the de Sitter invariance in the λΦ 4 theory in comparison with the Sine–Gordon model, where it was possible.« less

  20. Earth’s gravity and the cosmological constant: a worked example

    NASA Astrophysics Data System (ADS)

    Pereira, J. A. M.

    2016-03-01

    The cosmological constant regained the attention of the scientific community following the recent discovery of the accelerated expansion of the Universe. Consequently, interest in the subject increased amongst the public such that it now often appears in the classroom and popular science publications. The purpose of this article is to use basic concepts of Newtonian mechanics, like dynamics, kinetic energy and potential energy diagrams, in a scenario where the cosmological constant’s action, considered as being an inertial force driven by the accelerated expansion of the Universe, could counteract Earth’s gravity. The effect that the cosmological constant might have near the Earth’s surface is discussed showing how everyday life would change. This is done in such a way that makes it accessible to students in their first year of college. Finally, the modern interpretation of the cosmological constant, associated with the existence of dark energy, is briefly discussed along with upper limit estimations for its value based on the anthropic principle.

  1. Stiffness-constant variation in nickel-based alloys: Experiment and theory

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

    Hennion, M.; Hennion, B.

    1979-01-01

    Recent measurements of the spin-wave stiffness constant in several nickel alloys at various concentrations are interpreted within a random-phase approximation, coherent-potential approximation (RPA-CPA) band model which uses the Hartree-Fock approximation to treat the intraatomic correlations. We give a theoretical description of the possible impurity states in the Hartree-Fock approximation. This allows the determination of the Hartree-Fock solutions which can account for the stiffness-constant behavior and the magnetic moment on the impurity for all the investigated alloys. For alloys such as NiCr, NiV, NiMo, and NiRu, the magnetizations of which deviate from the Slater-Pauling curve, our determination does not correspond tomore » previous works and is consequently discussed. The limits of the model appear mainly due to local-environment effects; in the case of NiMn, it is found that a ternary-alloy model with some Mn atoms in the antiferromagnetic state can account for both stiffness-constant and magnetization behaviors.« less

  2. Advanced concepts for transformers pressboard dielectric constant and mechanical strength

    NASA Astrophysics Data System (ADS)

    1982-03-01

    Of the numerous electrical considerations in a material, the value of the dielectric constant serves as an important criterion in designing proper insulation systems. Ways to reduce the dielectric constant of solid (fibrous) insulating materials were investigated. A literature search was made on cellulosic and synthetic fibers and also additives which offered the potential for dielectric constant reduction of the solid insulation. Sample board structures were produced in the laboratory and tested for electrical, mechanical and chemical characteristics. Electrical tests determined the suitability of the material at transformer test and operating conditions. The mechanical tests established the physical characteristics of the modified board structures. Chemical tests checked the conductivity of the aqueous extract, acidity, and ash content. Further, compatibility with transformer oil and some aging tests were performed. An actual computer transformer design was made based on one of the modified board structures and the reduction in core steel and transformer losses were shown.

  3. Is the cosmological constant screened in Liouville gravity with matter?

    DOE PAGES

    Inami, Takeo; Koyama, Yoji; Nakayama, Yu; ...

    2015-05-19

    In this study, there has been a proposal that infrared quantum effects of massless interacting field theories in de Sitter space may provide time-dependent screening of the cosmological constant. As a concrete model of the proposal, we study the three loop corrections to the energy–momentum tensor of massless λΦ 4 theory in the background of classical Liouville gravity in D = 2 dimensional de Sitter space. We find that the cosmological constant is screened, in sharp contrast to the massless λΦ 4 theory in D = 4 dimensions due to the sign difference between the cosmological constant of the Liouvillemore » gravity and that of the Einstein gravity. To argue for the robustness of our prediction, we introduce the concept of time-dependent infrared counter-terms and examine if they recover the de Sitter invariance in the λΦ 4 theory in comparison with the Sine–Gordon model, where it was possible.« less

  4. Preliminary Planck constant measurements via UME oscillating magnet Kibble balance

    NASA Astrophysics Data System (ADS)

    Ahmedov, H.; Babayiğit Aşkın, N.; Korutlu, B.; Orhan, R.

    2018-06-01

    The UME Kibble balance project was initiated in the second half of 2014. During this period we have studied the theoretical aspects of Kibble balances, in which an oscillating magnet generates AC Faraday’s voltage in a stationary coil, and constructed a trial version to implement this idea. The remarkable feature of this approach is that it can establish the link between the Planck constant and a macroscopic mass by one single experiment in the most natural way. Weak dependences on variations of environmental and experimental conditions, small size, and other useful features offered by this novel approach reduce the complexity of the experimental set-up. This paper describes the principles of the oscillating magnet Kibble balance and gives details of the preliminary Planck constant measurements. The value of the Planck constant determined with our apparatus is \\boldsymbol{h}/{{\\boldsymbol{h}}\\boldsymbol 90}={1}{.000} {004}~ , with a relative standard uncertainty of 6 ppm.

  5. History and progress on accurate measurements of the Planck constant

    NASA Astrophysics Data System (ADS)

    Steiner, Richard

    2013-01-01

    The measurement of the Planck constant, h, is entering a new phase. The CODATA 2010 recommended value is 6.626 069 57 × 10-34 J s, but it has been a long road, and the trip is not over yet. Since its discovery as a fundamental physical constant to explain various effects in quantum theory, h has become especially important in defining standards for electrical measurements and soon, for mass determination. Measuring h in the International System of Units (SI) started as experimental attempts merely to prove its existence. Many decades passed while newer experiments measured physical effects that were the influence of h combined with other physical constants: elementary charge, e, and the Avogadro constant, NA. As experimental techniques improved, the precision of the value of h expanded. When the Josephson and quantum Hall theories led to new electronic devices, and a hundred year old experiment, the absolute ampere, was altered into a watt balance, h not only became vital in definitions for the volt and ohm units, but suddenly it could be measured directly and even more accurately. Finally, as measurement uncertainties now approach a few parts in 108 from the watt balance experiments and Avogadro determinations, its importance has been linked to a proposed redefinition of a kilogram unit of mass. The path to higher accuracy in measuring the value of h was not always an example of continuous progress. Since new measurements periodically led to changes in its accepted value and the corresponding SI units, it is helpful to see why there were bumps in the road and where the different branch lines of research joined in the effort. Recalling the bumps along this road will hopefully avoid their repetition in the upcoming SI redefinition debates. This paper begins with a brief history of the methods to measure a combination of fundamental constants, thus indirectly obtaining the Planck constant. The historical path is followed in the section describing how the improved

  6. Vicinal fluorine-fluorine coupling constants: Fourier analysis.

    PubMed

    San Fabián, J; Westra Hoekzema, A J A

    2004-10-01

    Stereochemical dependences of vicinal fluorine-fluorine nuclear magnetic resonance coupling constants (3JFF) have been studied with the multiconfigurational self-consistent field in the restricted active space approach, with the second-order polarization propagator approximation (SOPPA), and with density functional theory. The SOPPA results show the best overall agreement with experimental couplings. The relationship with the dihedral angle between the coupled fluorines has been studied by Fourier analysis, the result is very different from that of proton-proton couplings. The Fourier coefficients do not resemble those of a typical Karplus equation. The four nonrelativistic contributions to the coupling constants of 1,2-difluoroethane configurations have been studied separately showing that up to six Fourier coefficients are required to reproduce the calculated values satisfactorily. Comparison with Fourier coefficients for matching hydrogen fluoride dimer configurations suggests that the higher order Fourier coefficients (Cn> or =3) originate mainly from through-space Fermi contact interaction. The through-space interaction is the main reason 3JFF do not follow the Karplus equation. (c) 2004 American Institute of Physics

  7. Constant volume gas cell optical phase-shifter

    DOEpatents

    Phillion, Donald W.

    2002-01-01

    A constant volume gas cell optical phase-shifter, particularly applicable for phase-shifting interferometry, contains a sealed volume of atmospheric gas at a pressure somewhat different than atmospheric. An optical window is present at each end of the cell, and as the length of the cell is changed, the optical path length of a laser beam traversing the cell changes. The cell comprises movable coaxial tubes with seals and a volume equalizing opening. Because the cell is constant volume, the pressure, temperature, and density of the contained gas do not change as the cell changes length. This produces an exactly linear relationship between the change in the length of the gas cell and the change in optical phase of the laser beam traversing it. Because the refractive index difference between the gas inside and the atmosphere outside is very much the same, a large motion must be made to change the optical phase by the small fraction of a wavelength that is required by phase-shifting interferometry for its phase step. This motion can be made to great fractional accuracy.

  8. Accelerating Sequential Gaussian Simulation with a constant path

    NASA Astrophysics Data System (ADS)

    Nussbaumer, Raphaël; Mariethoz, Grégoire; Gravey, Mathieu; Gloaguen, Erwan; Holliger, Klaus

    2018-03-01

    Sequential Gaussian Simulation (SGS) is a stochastic simulation technique commonly employed for generating realizations of Gaussian random fields. Arguably, the main limitation of this technique is the high computational cost associated with determining the kriging weights. This problem is compounded by the fact that often many realizations are required to allow for an adequate uncertainty assessment. A seemingly simple way to address this problem is to keep the same simulation path for all realizations. This results in identical neighbourhood configurations and hence the kriging weights only need to be determined once and can then be re-used in all subsequent realizations. This approach is generally not recommended because it is expected to result in correlation between the realizations. Here, we challenge this common preconception and make the case for the use of a constant path approach in SGS by systematically evaluating the associated benefits and limitations. We present a detailed implementation, particularly regarding parallelization and memory requirements. Extensive numerical tests demonstrate that using a constant path allows for substantial computational gains with very limited loss of simulation accuracy. This is especially the case for a constant multi-grid path. The computational savings can be used to increase the neighbourhood size, thus allowing for a better reproduction of the spatial statistics. The outcome of this study is a recommendation for an optimal implementation of SGS that maximizes accurate reproduction of the covariance structure as well as computational efficiency.

  9. A Brief History of the J.P. Das Developmental Disabilities Centre

    ERIC Educational Resources Information Center

    Sobsey, Dick

    2008-01-01

    The J.P. Das Developmental Disabilities Centre celebrated its 40th anniversary on September 1, 2007, followed by The University of Alberta's 100th anniversary in 2008. The year 2008 also brought the appointment of a new Director for the Centre. As the immediate past Director of the Centre, the author recounts some of the history of the J.P. Das…

  10. Accurate Measurements of the Dielectric Constant of Seawater at L Band

    NASA Technical Reports Server (NTRS)

    Lang, Roger; Zhou, Yiwen; Utku, Cuneyt; Le Vine, David

    2016-01-01

    This paper describes measurements of the dielectric constant of seawater at a frequency of 1.413 GHz, the center of the protected band (i.e., passive use only) used in the measurement of sea surface salinity from space. The objective of the measurements is to accurately determine the complex dielectric constant of seawater as a function of salinity and temperature. A resonant cylindrical microwave cavity in transmission mode has been employed to make the measurements. The measurements are made using standard seawater at salinities of 30, 33, 35, and 38 practical salinity units over a range of temperatures from 0 degree C to 35 degree C in 5 degree C intervals. Repeated measurements have been made at each temperature and salinity. Mean values and standard deviations are then computed. The total error budget indicates that the real and imaginary parts of the dielectric constant have a combined standard uncertainty of about 0.3 over the range of salinities and temperatures considered. The measurements are compared with the dielectric constants obtained from the model functions of Klein and Swift and those of Meissner and Wentz. The biggest differences occur at low and high temperatures.

  11. Invited Review Article: Measurements of the Newtonian constant of gravitation, G

    NASA Astrophysics Data System (ADS)

    Rothleitner, C.; Schlamminger, S.

    2017-11-01

    By many accounts, the Newtonian constant of gravitation G is the fundamental constant that is most difficult to measure accurately. Over the past three decades, more than a dozen precision measurements of this constant have been performed. However, the scatter of the data points is much larger than the uncertainties assigned to each individual measurement, yielding a Birge ratio of about five. Today, G is known with a relative standard uncertainty of 4.7 × 10-5, which is several orders of magnitudes greater than the relative uncertainties of other fundamental constants. In this article, various methods to measure G are discussed. A large array of different instruments ranging from the simple torsion balance to the sophisticated atom interferometer can be used to determine G. Some instruments, such as the torsion balance can be used in several different ways. In this article, the advantages and disadvantages of different instruments as well as different methods are discussed. A narrative arc from the historical beginnings of the different methods to their modern implementation is given. Finally, the article ends with a brief overview of the current state of the art and an outlook.

  12. Invited Review Article: Measurements of the Newtonian constant of gravitation, G.

    PubMed

    Rothleitner, C; Schlamminger, S

    2017-11-01

    By many accounts, the Newtonian constant of gravitation G is the fundamental constant that is most difficult to measure accurately. Over the past three decades, more than a dozen precision measurements of this constant have been performed. However, the scatter of the data points is much larger than the uncertainties assigned to each individual measurement, yielding a Birge ratio of about five. Today, G is known with a relative standard uncertainty of 4.7 × 10 -5 , which is several orders of magnitudes greater than the relative uncertainties of other fundamental constants. In this article, various methods to measure G are discussed. A large array of different instruments ranging from the simple torsion balance to the sophisticated atom interferometer can be used to determine G. Some instruments, such as the torsion balance can be used in several different ways. In this article, the advantages and disadvantages of different instruments as well as different methods are discussed. A narrative arc from the historical beginnings of the different methods to their modern implementation is given. Finally, the article ends with a brief overview of the current state of the art and an outlook.

  13. Impact of non-constant concentration exposure on lethality of inhaled hydrogen cyanide.

    PubMed

    Sweeney, Lisa M; Sommerville, Douglas R; Channel, Stephen R

    2014-03-01

    The ten Berge model, also known as the toxic load model, is an empirical approach in hazard assessment modeling for estimating the relationship between the inhalation toxicity of a chemical and the exposure duration. The toxic load (TL) is normally expressed as a function of vapor concentration (C) and duration (t), with TL equaling C(n) × t being a typical form. Hypothetically, any combination of concentration and time that yields the same "toxic load" will give a constant biological response. These formulas have been developed and tested using controlled, constant concentration animal studies, but the validity of applying these assumptions to time-varying concentration profiles has not been tested. Experiments were designed to test the validity of the model under conditions of non-constant acute exposure. Male Sprague-Dawley rats inhaled constant or pulsed concentrations of hydrogen cyanide (HCN) generated in a nose-only exposure system for 5, 15, or 30 min. The observed lethality of HCN for the 11 different C versus t profiles was used to evaluate the ability of the model to adequately describe the lethality of HCN under the conditions of non-constant inhalation exposure. The model was found to be applicable under the tested conditions, with the exception of the median lethality of very brief, high concentration, discontinuous exposures.

  14. Determining Planck's Constant Using a Light-emitting Diode.

    ERIC Educational Resources Information Center

    Sievers, Dennis; Wilson, Alan

    1989-01-01

    Describes a method for making a simple, inexpensive apparatus which can be used to determine Planck's constant. Provides illustrations of a circuit diagram using one or more light-emitting diodes and a BASIC computer program for simplifying calculations. (RT)

  15. The ideal Kolmogorov inertial range and constant

    NASA Technical Reports Server (NTRS)

    Zhou, YE

    1993-01-01

    The energy transfer statistics measured in numerically simulated flows are found to be nearly self-similar for wavenumbers in the inertial range. Using the measured self-similar form, an 'ideal' energy transfer function and the corresponding energy flux rate were deduced. From this flux rate, the Kolmogorov constant was calculated to be 1.5, in excellent agreement with experiments.

  16. Microscopic theoretical study of frequency dependent dielectric constant of heavy fermion systems

    NASA Astrophysics Data System (ADS)

    Shadangi, Keshab Chandra; Rout, G. C.

    2017-05-01

    The dielectric polarization and the dielectric constant plays a vital role in the deciding the properties of the Heavy Fermion Systems. In the present communication we consider the periodic Anderson's Model which consists of conduction electron kinetic energy, localized f-electron kinetic energy and the hybridization between the conduction and localized electrons, besides the Coulomb correlation energy. We calculate dielectric polarization which involves two particle Green's functions which are calculated by using Zubarev's Green's function technique. Using the equations of motion of the fermion electron operators. Finally, the temperature and frequency dependent dielectric constant is calculated from the dielectric polarization function. The charge susceptibility and dielectric constant are computed numerically for different physical parameters like the position (Ef) of the f-electron level with respect to fermi level, the strength of the hybridization (V) between the conduction and localized f-electrons, Coulomb correlation potential temperature and optical phonon wave vector (q). The results will be discussed in a reference to the experimental observations of the dielectric constants.

  17. Analytical Considerations about the Cosmological Constant and Dark Energy

    NASA Astrophysics Data System (ADS)

    Abreu, Everton M. C.; de Assis, Leonardo P. G.; Dos Reis, Carlos M. L.

    The accelerated expansion of the universe has now been confirmed by several independent observations including those of high redshift type Ia supernovae, and the cosmic microwave background combined with the large scale structure of the universe. Another way of presenting this kinematic property of the universe is to postulate the existence of a new and exotic entity, with negative pressure, the dark energy (DE). In spite of observationally well established, no single theoretical model provides an entirely compelling framework within which cosmic acceleration or DE can be understood. At present all existing observational data are in agreement with the simplest possibility that the cosmological constant be a candidate for DE. This case is internally self-consistent and noncontradictory. The extreme smallness of the cosmological constant expressed in either Planck, or even atomic units means only that its origin is not related to strong, electromagnetic, and weak interactions. Although in this case DE reduces to only a single fundamental constant we still have no derivation from any underlying quantum field theory for its small value. From the principles of quantum cosmologies, for example, it is possible to obtain the reason for an inverse-square law for the cosmological constant with no conflict with observations. Despite the fact that this general expression is well known, in this work we introduce families of analytical solutions for the scale factor different from the current literature. The knowledge of the scale factor behavior might shed some light on these questions mentioned above since the entire evolution of a homogeneous isotropic universe is contained in the scale factor. We use different parameters for these solutions and with these parameters we establish a connection with the equation of state for different DE scenarios.

  18. ESTIMATION OF CARBOXYLIC ACID ESTER HYDROLYSIS RATE CONSTANTS

    EPA Science Inventory

    SPARC chemical reactivity models were extended to calculate hydrolysis rate constants for carboxylic acid esters from molecular structure. The energy differences between the initial state and the transition state for a molecule of interest are factored into internal and external...

  19. Binding constants of membrane-anchored receptors and ligands depend strongly on the nanoscale roughness of membranes.

    PubMed

    Hu, Jinglei; Lipowsky, Reinhard; Weikl, Thomas R

    2013-09-17

    Cell adhesion and the adhesion of vesicles to the membranes of cells or organelles are pivotal for immune responses, tissue formation, and cell signaling. The adhesion processes depend sensitively on the binding constant of the membrane-anchored receptor and ligand proteins that mediate adhesion, but this constant is difficult to measure in experiments. We have investigated the binding of membrane-anchored receptor and ligand proteins with molecular dynamics simulations. We find that the binding constant of the anchored proteins strongly decreases with the membrane roughness caused by thermally excited membrane shape fluctuations on nanoscales. We present a theory that explains the roughness dependence of the binding constant for the anchored proteins from membrane confinement and that relates this constant to the binding constant of soluble proteins without membrane anchors. Because the binding constant of soluble proteins is readily accessible in experiments, our results provide a useful route to compute the binding constant of membrane-anchored receptor and ligand proteins.

  20. A nuclear data approach for the Hubble constant measurements

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

    Pritychenko, B.

    2015-06-09

    An extraordinary number of Hubble constant measurements challenges physicists with selection of the best numerical value. The standard U.S. Nuclear Data Program (USNDP) codes and procedures have been applied to resolve this issue. The nuclear data approach has produced the most probable or recommended Hubble constant value of 67.00(770) (km/sec)/Mpc. This recommended value is based on the last 25 years of experimental research and includes contributions from different types of measurements. The present result implies (14.6±1.7) x 10 9 years as a rough estimate for the age of the Universe. The complete list of recommended results is given and possiblemore » implications are discussed.« less

  1. Rocket calibration of the Nimbus 6 solar constant measurements.

    PubMed

    Duncan, C H; Harrison, R G; Hickey, J R; Kendall, J M; Thekaekara, M P; Willson, R C

    1977-10-01

    Total solar irradiance was observed simultaneously outside the earth's atmosphere by three types of absolute cavity radiometers and duplicates of four of the Nimbus 6 Earth Radiation Budget (ERB) solar channels in a June 1976 Sounding Rocket Experiment. The preliminary average solar constant result from the cavity radiometers is 1367 W m(-2) with an uncertainty of less than +/-0.5% in SI units. The duplicate ERB channel 3 on the rocket gave a value of 1389 W mm(-2) which agreed exactly with the Nimbus 6 ERB channel 3 measurement made simultaneously with the rocket flight. Therefore, Nimbus 6 ERB solar constant values should be reduced approximately 1.6% in order to convert the values to SI units.

  2. Cosmological perturbations of axion with a dynamical decay constant

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

    Kobayashi, Takeshi; INFN, Sezione di Trieste,Via Bonomea 265, 34136 Trieste; Takahashi, Fuminobu

    2016-08-25

    A QCD axion with a time-dependent decay constant has been known to be able to accommodate high-scale inflation without producing topological defects or too large isocurvature perturbations on CMB scales. We point out that a dynamical decay constant also has the effect of enhancing the small-scale axion isocurvature perturbations. The enhanced axion perturbations can even exceed the periodicity of the axion potential, and thus lead to the formation of axionic domain walls. Unlike the well-studied axionic walls, the walls produced from the enhanced perturbations are not bounded by cosmic strings, and thus would overclose the universe independently of the numbermore » of degenerate vacua along the axion potential.« less

  3. Third-order elastic constants of diamond determined from experimental data

    DOE PAGES

    Winey, J. M.; Hmiel, A.; Gupta, Y. M.

    2016-06-01

    The pressure derivatives of the second-order elastic constants (SOECs) of diamond were determined by analyzing previous sound velocity measurements under hydrostatic stress [McSkimin and Andreatch, J. Appl. Phys. 43, 294 (1972)]. Furthermore, our analysis corrects an error in the previously reported results.We present a complete and corrected set of third-order elastic constants (TOECs) using the corrected pressure derivatives, together with published data for the nonlinear elastic response of shock compressed diamond [Lang and Gupta, Phys. Rev. Lett. 106, 125502 (2011)] and it differs significantly from TOECs published previously.

  4. Constitutive Model Constants for Al7075-T651 and Al7075-T6

    NASA Astrophysics Data System (ADS)

    Brar, Nachhatter; Joshi, Vasant; Harris, Bryan

    2009-06-01

    Aluminum 7075-T651 and 7075-T6 are characterized at quasi-static and high strain rates to determine Johnson-Cook (J-C) strength and fracture model constants. Constitutive model constants are required as input to computer codes to simulate projectile (fragment) impact or similar impact events on structural components made of these material. J-C strength model constants (A, B, n, C, and m) for the two alloys are determined from tension stress-strain data at room and high temperature to 250^oC. J-C strength model constants for Al7075-T651 are: A=527 MPa, B=676 MPa, n=0.71, C=0.017, and m=1.61 and for Al7075-T6: A = 546 MPa, B = 674 MPa, n = 0.72, C = 0.059, and m =1.56. J-C fracture model constants are determined form quasi-static and high strain rate/high temperature tests on notched and smooth tension specimens. J-C fracture model constants for the two alloys are: Al7075-T651; D1 = 0.110, D2 = 0.573, D3= -3.4446, D4 = 0.016, and D 5= 1.099 and Al7075-T6; D1= 0.451 D2= -0.952 D3= -.068, D4 =0.036, and D5 = 0.697.

  5. Constant pressure mode extended simple gradient liquid chromatography system for micro and nanocolumns.

    PubMed

    Šesták, Jozef; Kahle, Vladislav

    2014-07-11

    Performing gradient liquid chromatography at constant pressure instead of constant flow rate has serious potential for shortening the analysis time and increasing the productivity of HPLC instruments that use gradient methods. However, in the constant pressure mode the decreasing column permeability during a long period of time negatively affects the repeatability of retention time. Thus a volume-based approach, in which the detector signal is plotted as a function of retention volume, must be taken into consideration. Traditional HPLC equipment, however, requires quite complex hardware and software modifications in order to work at constant pressure and in the volume-based mode. In this short communication, a low cost and easily feasible pressure-controlled extension of the previously described simple gradient liquid chromatography platform is proposed. A test mixture of four nitro esters was separated by 10-60% (v/v) acetone/water gradient and a high repeatability of retention volumes at 20MPa (RSD less than 0.45%) was realized. Separations were also performed at different values of pressure (20, 25, and 31MPa), and only small variations of the retention volumes (up to 0.8%) were observed. In this particular case, the gain in the analysis speed of 7% compared to the constant flow mode was realized at a constant pressure. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Tolman lengths and rigidity constants of multicomponent fluids: Fundamental theory and numerical examples

    NASA Astrophysics Data System (ADS)

    Aasen, Ailo; Blokhuis, Edgar M.; Wilhelmsen, Øivind

    2018-05-01

    The curvature dependence of the surface tension can be described by the Tolman length (first-order correction) and the rigidity constants (second-order corrections) through the Helfrich expansion. We present and explain the general theory for this dependence for multicomponent fluids and calculate the Tolman length and rigidity constants for a hexane-heptane mixture by use of square gradient theory. We show that the Tolman length of multicomponent fluids is independent of the choice of dividing surface and present simple formulae that capture the change in the rigidity constants for different choices of dividing surface. For multicomponent fluids, the Tolman length, the rigidity constants, and the accuracy of the Helfrich expansion depend on the choice of path in composition and pressure space along which droplets and bubbles are considered. For the hexane-heptane mixture, we find that the most accurate choice of path is the direction of constant liquid-phase composition. For this path, the Tolman length and rigidity constants are nearly linear in the mole fraction of the liquid phase, and the Helfrich expansion represents the surface tension of hexane-heptane droplets and bubbles within 0.1% down to radii of 3 nm. The presented framework is applicable to a wide range of fluid mixtures and can be used to accurately represent the surface tension of nanoscopic bubbles and droplets.

  7. High-temperature langatate elastic constants and experimental validation up to 900 degrees C.

    PubMed

    Davulis, Peter M; da Cunha, Mauricio Pereira

    2010-01-01

    This paper reports on a set of langatate (LGT) elastic constants extracted from room temperature to 1100 degrees C using resonant ultrasound spectroscopy techniques and an accompanying assessment of these constants at high temperature. The evaluation of the constants employed SAW device measurements from room temperature to 900 degrees C along 6 different LGT wafer orientations. Langatate parallelepipeds and wafers were aligned, cut, ground, and polished, and acoustic wave devices were fabricated at the University of Maine facilities along specific orientations for elastic constant extraction and validation. SAW delay lines were fabricated on LGT wafers prepared at the University of Maine using 100-nm platinumrhodium- zirconia electrodes capable of withstanding temperatures up to 1000 degrees C. The numerical predictions based on the resonant ultrasound spectroscopy high-temperature constants were compared with SAW phase velocity, fractional frequency variation, and temperature coefficients of delay extracted from SAW delay line frequency response measurements. In particular, the difference between measured and predicted fractional frequency variation is less than 2% over the 25 degrees C to 900 degrees C temperature range and within the calculated and measured discrepancies. Multiple temperature-compensated orientations at high temperature were predicted and verified in this paper: 4 of the measured orientations had turnover temperatures (temperature coefficient of delay = 0) between 200 and 420 degrees C, and 2 had turnover temperatures below 100 degrees C. In summary, this work reports on extracted high-temperature elastic constants for LGT up to 1100 degrees C, confirmed the validity of those constants by high-temperature SAW device measurements up to 900 degrees C, and predicted and identified temperature-compensated LGT orientations at high temperature.

  8. The Physiology Constant Database of Teen-Agers in Beijing

    PubMed Central

    Wei-Qi, Wei; Guang-Jin, Zhu; Cheng-Li, Xu; Shao-Mei, Han; Bao-Shen, Qi; Li, Chen; Shu-Yu, Zu; Xiao-Mei, Zhou; Wen-Feng, Hu; Zheng-Guo, Zhang

    2004-01-01

    Physiology constants of adolescents are important to understand growing living systems and are a useful reference in clinical and epidemiological research. Until recently, physiology constants were not available in China and therefore most physiologists, physicians, and nutritionists had to use data from abroad for reference. However, the very difference between the Eastern and Western races casts doubt on the usefulness of overseas data. We have therefore created a database system to provide a repository for the storage of physiology constants of teen-agers in Beijing. The several thousands of pieces of data are now divided into hematological biochemistry, lung function, and cardiac function with all data manually checked before being transferred into the database. The database was accomplished through the development of a web interface, scripts, and a relational database. The physiology data were integrated into the relational database system to provide flexible facilities by using combinations of various terms and parameters. A web browser interface was designed for the users to facilitate their searching. The database is available on the web. The statistical table, scatter diagram, and histogram of the data are available for both anonym and user according to queries, while only the user can achieve detail, including download data and advanced search. PMID:15258669

  9. Modification of the erythrocyte membrane dielectric constant by alcohols.

    PubMed

    Orme, F W; Moronne, M M; Macey, R I

    1988-08-01

    Aliphatic alcohols are found to stimulate the transmembrane fluxes of a hydrophobic cation (tetraphenylarsonium, TPA) and anion (AN-12) 5-20 times in red blood cells. The results are analyzed using the Born-Parsegian equation (Parsegian, A., 1969, Nature (London) 221:844-846), together with the Clausius-Mossotti equation to calculate membrane dielectric energy barriers. Using established literature values of membrane thickness, native membrane dielectric constant, TPA ionic radius, and alcohol properties (partition coefficient, molar volume, dielectric constant), the TPA permeability data is predicted remarkably well by theory. If the radius of AN-12 is taken as 1.9 A, its permeability in the presence of butanol is also described by our analysis. Further, the theory quantitatively accounts for the data of Gutknecht and Tosteson (Gutknecht, J., Tosteson, D.C., 1970, J. Gen. Physiol. 55:359-374) covering alcohol-induced conductivity changes of 3 orders of magnitude in artificial bilayers. Other explanations including perturbations of membrane fluidity, surface charge, membrane thickness, and dipole potential are discussed. However, the large magnitude of the stimulation, the more pronounced effect on smaller ions, and the acceleration of both anions and cations suggest membrane dielectric constant change as the primary basis of alcohol effects.

  10. Determination of thermodynamic values of acidic dissociation constants and complexation constants of profens and their utilization for optimization of separation conditions by Simul 5 Complex.

    PubMed

    Riesová, Martina; Svobodová, Jana; Ušelová, Kateřina; Tošner, Zdeněk; Zusková, Iva; Gaš, Bohuslav

    2014-10-17

    In this paper we determine acid dissociation constants, limiting ionic mobilities, complexation constants with β-cyclodextrin or heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin, and mobilities of resulting complexes of profens, using capillary zone electrophoresis and affinity capillary electrophoresis. Complexation parameters are determined for both neutral and fully charged forms of profens and further corrected for actual ionic strength and variable viscosity in order to obtain thermodynamic values of complexation constants. The accuracy of obtained complexation parameters is verified by multidimensional nonlinear regression of affinity capillary electrophoretic data, which provides the acid dissociation and complexation parameters within one set of measurements, and by NMR technique. A good agreement among all discussed methods was obtained. Determined complexation parameters were used as input parameters for simulations of electrophoretic separation of profens by Simul 5 Complex. An excellent agreement of experimental and simulated results was achieved in terms of positions, shapes, and amplitudes of analyte peaks, confirming the applicability of Simul 5 Complex to complex systems, and accuracy of obtained physical-chemical constants. Simultaneously, we were able to demonstrate the influence of electromigration dispersion on the separation efficiency, which is not possible using the common theoretical approaches, and predict the electromigration order reversals of profen peaks. We have shown that determined acid dissociation and complexation parameters in combination with tool Simul 5 Complex software can be used for optimization of separation conditions in capillary electrophoresis. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. History and progress on accurate measurements of the Planck constant.

    PubMed

    Steiner, Richard

    2013-01-01

    The measurement of the Planck constant, h, is entering a new phase. The CODATA 2010 recommended value is 6.626 069 57 × 10(-34) J s, but it has been a long road, and the trip is not over yet. Since its discovery as a fundamental physical constant to explain various effects in quantum theory, h has become especially important in defining standards for electrical measurements and soon, for mass determination. Measuring h in the International System of Units (SI) started as experimental attempts merely to prove its existence. Many decades passed while newer experiments measured physical effects that were the influence of h combined with other physical constants: elementary charge, e, and the Avogadro constant, N(A). As experimental techniques improved, the precision of the value of h expanded. When the Josephson and quantum Hall theories led to new electronic devices, and a hundred year old experiment, the absolute ampere, was altered into a watt balance, h not only became vital in definitions for the volt and ohm units, but suddenly it could be measured directly and even more accurately. Finally, as measurement uncertainties now approach a few parts in 10(8) from the watt balance experiments and Avogadro determinations, its importance has been linked to a proposed redefinition of a kilogram unit of mass. The path to higher accuracy in measuring the value of h was not always an example of continuous progress. Since new measurements periodically led to changes in its accepted value and the corresponding SI units, it is helpful to see why there were bumps in the road and where the different branch lines of research joined in the effort. Recalling the bumps along this road will hopefully avoid their repetition in the upcoming SI redefinition debates. This paper begins with a brief history of the methods to measure a combination of fundamental constants, thus indirectly obtaining the Planck constant. The historical path is followed in the section describing how the

  12. Large dielectric constant in zirconia polypyrrole hybrid nanocomposites.

    PubMed

    Dey, Ashis; De, S K

    2007-06-01

    Zirconia nanoparticles have been synthesized by a novel two-reverse emulsion technique and combined with polypyrrole (PPY) to form ZrO2-PPY nanocomposites. Complex impedance and dielectric permittivity of ZrO2-PPY nanocomposite have been investigated as a function of frequency and temperature for different compositions. The composite samples are characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning and transmission electron microscopy. The composites reveal ordered semiconducting behaviour. Polypyrrole is the major component in electrical transport process of the samples. A very large dielectric constant of about 12,000 at room temperature has been observed. The colossal dielectric constant is mainly dominated by interfacial polarization due to Maxwell-Wagner relaxation effect. Two completely separate groups of dielectric relaxation have been observed. The low frequency dielectric relaxation arises from surface defect states of zirconia nanoparticles. The broad peak at high frequency is due to Maxwell-Wagner type polarization.

  13. Periodic Inclusion—Matrix Microstructures with Constant Field Inclusions

    NASA Astrophysics Data System (ADS)

    Liu, Liping; James, Richard D.; Leo, Perry H.

    2007-04-01

    We find a class of special microstructures consisting of a periodic array of inclusions, with the special property that constant magnetization (or eigenstrain) of the inclusion implies constant magnetic field (or strain) in the inclusion. The resulting inclusions, which we term E-inclusions, have the same property in a finite periodic domain as ellipsoids have in infinite space. The E-inclusions are found by mapping the magnetostatic or elasticity equations to a constrained minimization problem known as a free-boundary obstacle problem. By solving this minimization problem, we can construct families of E-inclusions with any prescribed volume fraction between zero and one. In two dimensions, our results coincide with the microstructures first introduced by Vigdergauz,[1,2] while in three dimensions, we introduce a numerical method to calculate E-inclusions. E-inclusions extend the important role of ellipsoids in calculations concerning phase transformations and composite materials.

  14. Size- and temperature-dependent Hamaker constants for heterogeneous systems of interacting nanoparticles

    NASA Astrophysics Data System (ADS)

    Pinchuk, P.; Pinchuk, A. O.

    2016-09-01

    Hamaker-Lifshitz constants are used to calculate van der Waals interaction forces between small particles in solution. Typically, these constants are size-independent and material specific. According to the Lifshitz theory, the Hamaker-Lifshitz constants can be calculated by taking integrals that include the dielectric permittivity, as a function of frequency, of the interacting particles and the medium around particles. The dielectric permittivity of interacting metal nanoparticles can be calculated using the free-electron Drude model for metals. For bulk metals, the Drude model does is size independent. However, the conducting electrons in small metal nanoparticles exhibit surface scattering, which changes the complex dielectric permittivity function. Additionally, the Drude model can be modified to include temperature dependence. That is, an increase in temperature leads to thermal volume expansion and increased phonon population, which affect the scattering rate of the electrons and the plasma frequency. Both of these terms contribute significantly to the Drude model for the dielectric permittivity of the particles. In this work, we show theoretically that scattering of the free conducting electrons inside noble metal nanoparticles with the size of 1 - 50 nm leads to size-dependent dielectric permittivity and Hamaker-Lifshitz constants. In addition, we calculate numerically the Hamaker-Lifshitz constants for a variety of temperatures. The results of the study might be of interest for understanding colloidal stability of metal nanoparticles.

  15. Numerical determination of visible/NIR optical constants from laboratory spectra of HED meteorites

    NASA Astrophysics Data System (ADS)

    Davalos, Jorge A. G.; Carvano, Jorge Márcio; Blanco, Julio

    2017-03-01

    Radiative transfer models in particulate media (Hapke, 1981, 1993, 2012b; Shkuratov et al., 1999) are the most versatile tool that can be used to retrieve both composition and surface physical properties from observation of asteroids and other atmosphereless bodies of the Solar System. One caveat is that these methods require as input a sufficiently comprehensive set of optical constants of suitable template materials. These optical constants are the real and imaginary parts of the refractive indexes of the material as function of wavelength, and have to be derived from laboratory measurements of samples of minerals and meteorites. Optical constants can be calculated from a variety of types of measurements, and each has its problems and limitations. In particular, a problem with the determination of optical constants from measurement of reflectance is that the measurements need to be themselves interpreted using radiative transfer models. This is an issue because the number of parameters used in the most accurate versions of the radiative transfer models is large, and for most of the samples many of these parameters were not measured independently. As a result, attempts in the literature to retrieve optical constants from reflectance measurements tend to assume values for the unknown parameters, which can lead to uncertainties in the retrieved optical constants that can be difficult to quantify. In this work we propose a numerical method that allows the simultaneous inversion of the optical constant and the model parameters. This model is then applied to a set of reflectance spectra of 5 HED meteorites from the RELAB database that were measured with the same setup for samples with several particle size intervals. Our results indicate that our method is able to retrieve optical constants which are able to reproduce the measured reflectance of the samples over a large range (25-500 μm) of particle diameters. It is also found that the solutions obtained in this way

  16. Brief note on Ashtekar-Magnon-Das conserved quantities in quadratic curvature theories

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

    Pang Yi

    2011-04-15

    In this note, we correct a mistake in the mass formula in [N. Okuyama and J. i. Koga, Phys. Rev. D 71, 084009 (2005).] which generalizes the Ashtekar-Magnon-Das method to incorporate extended gravities with quadratic curvature terms. The corrected mass formula confirms that the black hole masses for recently discovered critical gravities vanish.

  17. Helicopter TEM parameters analysis and system optimization based on time constant

    NASA Astrophysics Data System (ADS)

    Xiao, Pan; Wu, Xin; Shi, Zongyang; Li, Jutao; Liu, Lihua; Fang, Guangyou

    2018-03-01

    Helicopter transient electromagnetic (TEM) method is a kind of common geophysical prospecting method, widely used in mineral detection, underground water exploration and environment investigation. In order to develop an efficient helicopter TEM system, it is necessary to analyze and optimize the system parameters. In this paper, a simple and quantitative method is proposed to analyze the system parameters, such as waveform, power, base frequency, measured field and sampling time. A wire loop model is used to define a comprehensive 'time constant domain' that shows a range of time constant, analogous to a range of conductance, after which the characteristics of the system parameters in this domain is obtained. It is found that the distortion caused by the transmitting base frequency is less than 5% when the ratio of the transmitting period to the target time constant is greater than 6. When the sampling time window is less than the target time constant, the distortion caused by the sampling time window is less than 5%. According to this method, a helicopter TEM system, called CASHTEM, is designed, and flight test has been carried out in the known mining area. The test results show that the system has good detection performance, verifying the effectiveness of the method.

  18. Does 'anchor sleep' entrain circadian rhythms? Evidence from constant routine studies.

    PubMed Central

    Minors, D S; Waterhouse, J M

    1983-01-01

    Experiments have been performed in an isolation unit to investigate the effects of abnormal sleep-waking schedules upon circadian rhythms of renal excretion and deep-body temperature. In confirmation of previous work, nychthemeral rhythms appeared to be 'anchored' to a 24 h period if 4 h sleep was taken regularly each day, even though another 4 h was taken irregularly. The endogenous components were investigated by assessing circadian rhythmicity under constant routine conditions, that is, when rhythmic influences in the environment and sleep-waking pattern had been minimized. Analysis of the constant routine data indicated the presence of a rhythmic component which had been stabilized to a period of 24 h by the 'anchor sleep'. In addition, a delayed component was also present. The starting time of the constant routines produced a direct effect upon the rhythms, which was presumed to result from removing the 'masking' effect that sleep normally exerts upon rhythms. There was some evidence that the relative importance of the masking effect and the delayed component depended upon the variable under consideration. The implications of these findings, in terms of the effects of anchor sleep, the presence of more than one internal clock and the usefulness of constant routines, are discussed. PMID:6663508

  19. Determination of the dispersion constant in a constrained vapor bubble thermosyphon

    NASA Technical Reports Server (NTRS)

    Dasgupta, Sunando; Plawsky, Joel L.; Wayner, Peter C., Jr.

    1995-01-01

    The isothermal profiles of the extended meniscus in a quartz cuvette were measured in a gravitational field using an image analyzing interferometer which is based on computer enhanced video microscopy of the naturally occurring interference fringes. The experimental results for heptane and pentane menisci were analyzed using the extended Young Laplace Equation. These isothermal results characterized the interfacial force field in-siru at the start of the heat transfer experiments by quantifying the dispersion constant, which is a function of the liquid-solid system and cleaning procedures. The experimentally obtained values of the disjoining pressure and the dispersion constants were compared to that predicted from the DLP theory and good agreements were obtained. The measurements are critical to the subsequent non-isothermal experiments because one of the major variables in the heat sink capability of the Constrained Vapor Bubble Thermosyphon, CVBT, is the dispersion constant. In all previous studies of micro heat pipes the value of the dispersion constant has been 'estimated'. One of the major advantages of the current glass cell is the ability to view the extended meniscus at all times. Experimentally, we find that the extended Young-Laplace Equation is an excellent model for the force field at the solid-liquid-vapor interfaces.

  20. Low energy determination of the QCD strong coupling constant on the lattice

    DOE PAGES

    Maezawa, Yu; Petreczky, Peter

    2016-09-28

    Here we present a determination of the strong coupling constant from lattice QCD using the moments of pseudo-scalar charmonium correlators calculated using highly improved staggerered quark action. We obtain a value α s( μ = mc) = 0.3397(56), which is the lowest energy determination of the strong coupling constant so far.

  1. How to obtain a cosmological constant from small exotic R4

    NASA Astrophysics Data System (ADS)

    Asselmeyer-Maluga, Torsten; Król, Jerzy

    2018-03-01

    In this paper we determine the cosmological constant as a topological invariant by applying certain techniques from low dimensional differential topology. We work with a small exotic R4 which is embedded into the standard R4. Any exotic R4 is a Riemannian smooth manifold with necessary non-vanishing curvature tensor. To determine the invariant part of such curvature we deal with a canonical construction of R4 where it appears as a part of the complex surface K 3 # CP(2) bar. Such R4's admit hyperbolic geometry. This fact simplifies significantly the calculations and enforces the rigidity of the expressions. In particular, we explain the smallness of the cosmological constant with a value consisting of a combination of (natural) topological invariant. Finally, the cosmological constant appears to be a topologically supported quantity.

  2. Organic solar cells based on high dielectric constant materials: An approach to increase efficiency

    NASA Astrophysics Data System (ADS)

    Hamam, Khalil Jumah Tawfiq

    The efficiency of organic solar cells still lags behind inorganic solar cells due to their low dielectric constant which results in a weakly screened columbic attraction between the photogenerated electron-hole system, therefore the probability of charge separating is low. Having an organic material with a high dielectric constant could be the solution to get separated charges or at least weakly bounded electron-hole pairs. Therefore, high dielectric constant materials have been investigated and studied by measuring modified metal-phthalocyanine (MePc) and polyaniline in pellets and thin films. The dielectric constant was investigated as a function of temperature and frequency in the range of 20Hz to1MHz. For MePc we found that the high dielectric constant was an extrinsic property due to water absorption and the formation of hydronuim ion allowed by the ionization of the functional groups such as sulphonated and carboxylic groups. The dielectric constant was high at low frequencies and decreasing as the frequency increase. Investigated materials were applied in fabricated bilayer heterojunction organic solar cells. The application of these materials in an organic solar cells show a significant stability under room conditions rather than improvement in their efficiency.

  3. Characterizing full matrix constants of piezoelectric single crystals with strong anisotropy using two samples

    NASA Astrophysics Data System (ADS)

    Tang, Liguo; Zhang, Yang; Cao, Wenwu

    2016-10-01

    Although the self-consistency of the full matrix material constants of a piezoelectric sample obtained by the resonant ultrasonic spectroscopy technique can be guaranteed because all constants come from the same sample, it is a great challenge to determine the constants of a piezoelectric sample with strong anisotropy because it might not be possible to identify enough resonance modes from the resonance spectrum. To overcome this difficulty, we developed a strategy to use two samples of similar geometries to increase the number of easy identifiable modes. Unlike the IEEE resonance methods, sample-to-sample variation here is negligible because the two samples have almost the same dimensions, cut from the same specimen and poled under the same conditions. Using this method, we have measured the full matrix constants of a [011]c poled 0.71Pb(Mg1/3Nb2/3)O3-0.29PbTiO3 single crystal, which has 17 independent constants. The self-consistency of the obtained results is checked by comparing the calculated elastic stiffness constants c33 D , c44 D , and c55 D with those directly measured ones using the ultrasonic pulse-echo method.

  4. EFFECTIVE ACIDITY CONSTANT BEHAVIOR NEAR ZERO CHARGE CONDITIONS

    EPA Science Inventory

    Surface site (>SOH group) acidity reactions require expressions of the form: Ka = [>SOHn-1(z-1)]aH+EXP(-DG/RT)/[>SOHnz] (where all variables have their usual meaning). One can rearrange this expression to generate an effective acidity constant historically defined as: Qa = Ka...

  5. L-band Dielectric Constant Measurements of Seawater (Oral presentation and SMOS Poster)

    NASA Technical Reports Server (NTRS)

    Lang, Roger H.; Utku, Cuneyt; LeVine, David M.

    2003-01-01

    This paper describes a resonant cavity technique for the measurement of the dielectric constant of seawater as a function of its salinity. Accurate relationships between salinity and dielectric constant (which determines emissivity) are needed for sensor systems such as SMOS and Aquarius that will monitor salinity from space in the near future. The purpose of the new measurements is to establish the dependence of the dielectric constant of seawater on salinity in contemporary units (e.g. psu) and to take advantage of modern instrumentation to increase the accuracy of these measurements. The measurement device is a brass cylindrical cavity 16cm in diameter and 7cm in height. The seawater is introduced into the cavity through a slender glass tube having an inner diameter of 0.1 mm. By assuming that this small amount of seawater slightly perturbs the internal fields in the cavity, perturbation theory can be employed. A simple formula results relating the real part of the dielectric constant to the change in resonant frequency of the cavity. In a similar manner, the imaginary part of the dielectric constant is related to the change in the cavity s Q. The expected accuracy of the cavity technique is better than 1% for the real part and 1 to 2% for the imaginary part. Presently, measurements of methanol have been made and agree with precision measurements in the literature to within 1% in both real and imaginary parts. Measurements have been made of the dielectric constant of seawater samples from Ocean Scientific in the United Kingdom with salinities of 10, 30, 35 and 38 psu. All measurements were made at room temperature. Plans to make measurements at a range of temperatures and salinities will be discussed.

  6. Determining the Optimal Values of Exponential Smoothing Constants--Does Solver Really Work?

    ERIC Educational Resources Information Center

    Ravinder, Handanhal V.

    2013-01-01

    A key issue in exponential smoothing is the choice of the values of the smoothing constants used. One approach that is becoming increasingly popular in introductory management science and operations management textbooks is the use of Solver, an Excel-based non-linear optimizer, to identify values of the smoothing constants that minimize a measure…

  7. Radiation balances and the solar constant

    NASA Technical Reports Server (NTRS)

    Crommelynck, D.

    1981-01-01

    The radiometric concepts are defined in order to consider various types of radiation balances and relate them to the diabetic form of the energy balance. Variability in space and time of the components of the radiation field are presented. A specific concept for sweeping which is tailored to the requirements is proposed. Finally, after establishing the truncated character of the present knowledge of the radiation balance. The results of the last observations of the solar constant are given. Ground and satellite measurement techniques are discussed.

  8. The Newton constant and gravitational waves in some vector field adjusting mechanisms

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

    Santillán, Osvaldo P.; Scornavacche, Marina, E-mail: firenzecita@hotmail.com, E-mail: marina.scorna@hotmail.com

    At the present, there exist some Lorentz breaking scenarios which explain the smallness of the cosmological constant at the present era [1]–[2]. An important aspect to analyze is the propagation of gravitational waves and the screening or enhancement of the Newton constant G {sub N} in these models. The problem is that the Lorentz symmetry breaking terms may induce an unacceptable value of the Newton constant G {sub N} or introduce longitudinal modes in the gravitational wave propagation. Furthermore this breaking may spoil the standard dispersion relation ω= ck . In [3] the authors have presented a model suggesting thatmore » the behavior of the gravitational constant is correct for asymptotic times. In the present work, an explicit checking is made and we finally agree with these claims. Furthermore, it is suggested that the gravitational waves are also well behaved for large times. In the process, some new models with the same behavior are obtained, thus enlarging the list of possible adjustment mechanisms.« less

  9. A summary of the Planck constant determinations using the NRC Kibble balance

    NASA Astrophysics Data System (ADS)

    Wood, B. M.; Sanchez, C. A.; Green, R. G.; Liard, J. O.

    2017-06-01

    We present a summary of the Planck constant determinations using the NRC watt balance, now referred to as the NRC Kibble balance. The summary includes a reanalysis of the four determinations performed in late 2013, as well as three new determinations performed in 2016. We also present a number of improvements and modifications to the experiment resulting in lower noise and an improved uncertainty analysis. As well, we present a systematic error that had been previously unrecognized and we have quantified its correction. The seven determinations, using three different nominal masses and two different materials, are reanalysed in a manner consistent with that used by the CODATA Task Group on Fundamental Constants (TGFC) and includes a comprehensive assessment of correlations. The result is a Planck constant of 6.626 070 133(60)  ×10-34 Js and an inferred value of the Avogadro constant of 6.022 140 772(55)  ×1023 mol-1. These fractional uncertainties of less than 10-8 are the smallest published to date.

  10. A Limited In-Flight Evaluation of the Constant Current Loop Strain Measurement Method

    NASA Technical Reports Server (NTRS)

    Olney, Candida D.; Collura, Joseph V.

    1997-01-01

    For many years, the Wheatstone bridge has been used successfully to measure electrical resistance and changes in that resistance. However, the inherent problem of varying lead wire resistance can cause errors when the Wheatstone bridge is used to measure strain in a flight environment. The constant current loop signal-conditioning card was developed to overcome that difficulty. This paper describes a limited evaluation of the constant current loop strain measurement method as used in the F-16XL ship 2 Supersonic Laminar Flow Control flight project. Several identical strain gages were installed in close proximity on a shock fence which was mounted under the left wing of the F- 1 6XL ship 2. Two strain gage bridges were configured using the constant current loop, and two were configured using the Wheatstone bridge circuitry. Flight data comparing the output from the constant current loop configured gages to that of the Wheatstone bridges with respect to signal output, error, and noise are given. Results indicate that the constant current loop strain measurement method enables an increased output, unaffected by lead wire resistance variations, to be obtained from strain gages.

  11. Compilation of Henry's law constants (version 4.0) for water as solvent

    NASA Astrophysics Data System (ADS)

    Sander, R.

    2015-04-01

    Many atmospheric chemicals occur in the gas phase as well as in liquid cloud droplets and aerosol particles. Therefore, it is necessary to understand the distribution between the phases. According to Henry's law, the equilibrium ratio between the abundances in the gas phase and in the aqueous phase is constant for a dilute solution. Henry's law constants of trace gases of potential importance in environmental chemistry have been collected and converted into a uniform format. The compilation contains 17 350 values of Henry's law constants for 4632 species, collected from 689 references. It is also available at http://www.henrys-law.org.

  12. Formulas for the elastic constants of plates with integral waffle-like stiffening

    NASA Technical Reports Server (NTRS)

    Dow, Norris R; Libove, Charles; Hubka, Ralph E

    1954-01-01

    Formulas are derived for the fifteen elastic constants associated with bending, stretching, twisting, and shearing of plates with closely spaced integral ribbing in a variety of configurations and proportions. In the derivation the plates are considered, conceptually, as more uniform orthotropic plates somewhat on the order of plywood. The constants, which include the effectiveness of the ribs for resisting deformations other than bending and stretching in their longitudinal directions, are defined in terms of four coefficients, and theoretical and experimental methods for the evaluation of these coefficients are discussed. Four of the more important elastic constants are predicted by these formulas and are compared with test results. Good correlation is obtained. (author)

  13. 50 CFR 648.10 - VMS and DAS requirements for vessel owners/operators.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... notification. The owner of a vessel issued a limited access monkfish or red crab permit who is participating in... confirmation numbers for the current and immediately prior NE multispecies, monkfish, or red crab fishing trip... specified in § 648.94(c); and any vessel issued a limited access red crab permit subject to the red crab DAS...

  14. Locus of the apices of projectile trajectories under constant drag

    NASA Astrophysics Data System (ADS)

    Hernández-Saldaña, H.

    2017-11-01

    Using the hodograph method, we present an analytical solution for projectile coplanar motion under constant drag, parametrised by the velocity angle. We find the locus formed by the apices of the projectile trajectories, and discuss its implementation for the motion of a particle on an inclined plane in presence of Coulomb friction. The range and time of flight are obtained numerically, and we find that the optimal launching angle is smaller than in the drag-free case. This is a good example of a problem with constant dissipation of energy that includes curvature; it is appropriate for intermediate courses of mechanics.

  15. Remote Sensing of Salinity: The Dielectric Constant of Sea Water

    NASA Technical Reports Server (NTRS)

    LeVine, David M.; Lang, R.; Utku, C.; Tarkocin, Y.

    2011-01-01

    Global monitoring of sea surface salinity from space requires an accurate model for the dielectric constant of sea water as a function of salinity and temperature to characterize the emissivity of the surface. Measurements are being made at 1.413 GHz, the center frequency of the Aquarius radiometers, using a resonant cavity and the perturbation method. The cavity is operated in a transmission mode and immersed in a liquid bath to control temperature. Multiple measurements are made at each temperature and salinity. Error budgets indicate a relative accuracy for both real and imaginary parts of the dielectric constant of about 1%.

  16. Advances in the analysis and design of constant-torque springs

    NASA Technical Reports Server (NTRS)

    McGuire, John R.; Yura, Joseph A.

    1996-01-01

    In order to improve the design procedure of constant-torque springs used in aerospace applications, several new analysis techniques have been developed. These techniques make it possible to accurately construct a torque-rotation curve for any general constant-torque spring configuration. These new techniques allow for friction in the system to be included in the analysis, an area of analysis that has heretofore been unexplored. The new analysis techniques also include solutions for the deflected shape of the spring as well as solutions for drum and roller support reaction forces. A design procedure incorporating these new capabilities is presented.

  17. Solar Constant (SOLCON) Experiment: Ground Support Equipment (GSE) software development

    NASA Technical Reports Server (NTRS)

    Gibson, M. Alan; Thomas, Susan; Wilson, Robert

    1991-01-01

    The Solar Constant (SOLCON) Experiment, the objective of which is to determine the solar constant value and its variability, is scheduled for launch as part of the Space Shuttle/Atmospheric Laboratory for Application and Science (ATLAS) spacelab mission. The Ground Support Equipment (GSE) software was developed to monitor and analyze the SOLCON telemetry data during flight and to test the instrument on the ground. The design and development of the GSE software are discussed. The SOLCON instrument was tested during Davos International Solar Intercomparison, 1989 and the SOLCON data collected during the tests are analyzed to study the behavior of the instrument.

  18. Omnidirectional antenna having constant phase

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

    Sena, Matthew

    Various technologies presented herein relate to constructing and/or operating an antenna having an omnidirectional electrical field of constant phase. The antenna comprises an upper plate made up of multiple conductive rings, a lower ground-plane plate, a plurality of grounding posts, a conical feed, and a radio frequency (RF) feed connector. The upper plate has a multi-ring configuration comprising a large outer ring and several smaller rings of equal size located within the outer ring. The large outer ring and the four smaller rings have the same cross-section. The grounding posts ground the upper plate to the lower plate while maintainingmore » a required spacing/parallelism therebetween.« less

  19. Henry's law constants of polyols

    NASA Astrophysics Data System (ADS)

    Compernolle, S.; Müller, J.-F.

    2014-12-01

    Henry's law constants (HLC) are derived for several polyols bearing between 2 and 6 hydroxyl groups, based on literature data for water activity, vapour pressure and/or solubility. While deriving HLC and depending on the case, also infinite dilution activity coefficients (IDACs), solid state vapour pressures or activity coefficient ratios are obtained as intermediate results. An error analysis on the intermediate quantities and the obtained HLC is included. For most compounds, these are the first values reported, while others compare favourably with literature data in most cases. Using these values and those from a previous work (Compernolle and Müller, 2014), an assessment is made on the partitioning of polyols, diacids and hydroxy acids to droplet and aqueous aerosol.

  20. Penna Bit-String Model with Constant Population

    NASA Astrophysics Data System (ADS)

    de Oliveira, P. M. C.; de Oliveira, S. Moss; Sá Martins, J. S.

    We removed from the Penna model for biological aging any random killing Verhulst factor. Deaths are due only to genetic diseases and the population size is fixed, instead of fluctuating around some constant value. We show that these modifications give qualitatively the same results obtained in an earlier paper, where the random killings (used to avoid an exponential increase of the population) were applied only to newborns.

  1. Integration of DAS (distributed acoustic sensing) vertical seismic profile and geostatistically modeled lithology data to characterize an enhanced geothermal system.

    NASA Astrophysics Data System (ADS)

    Cronin, S. P.; Trainor Guitton, W.; Team, P.; Pare, A.; Jreij, S.; Powers, H.

    2017-12-01

    In March 2016, a 4-week field data acquisition took place at Brady's Natural Lab (BNL), an enhanced geothermal system (EGS) in Fallan, NV. During these 4 weeks, a vibe truck executed 6,633 sweeps, recorded by nodal seismometers, horizontal distributed acoustic sensing (DAS) cable, and 400 meters of vertical DAS cable. DAS provides lower signal to noise ratio than traditional geophones but better spatial resolution. The analysis of DAS VSP included Fourier transform, and filtering to remove all up-going energy. Thus, allowing for accurate first arrival picking. We present an example of the Gradual Deformation Method (GDM) using DAS VSP and lithological data to produce a distribution of valid velocity models of BNL. GDM generates continuous perturbations of prior model realizations seeking the best match to the data (i.e. minimize the misfit). Prior model realizations honoring the lithological data were created using sequential Gaussian simulation, a commonly used noniterative geostatistical method. Unlike least-squares-based methods of inversion, GDM readily incorporates a priori information, such as a variogram calculated from well-based lithology information. Additionally, by producing a distribution of models, as opposed to one optimal model, GDM allows for uncertainty quantification. This project aims at assessing the integrated technologies ability to monitor changes in the water table (possibly to one meter resolution) by exploiting the dependence of seismic wave velocities on water saturation of the subsurface. This project, which was funded in part by the National Science Foundation, is a part of the PoroTomo project, funded by a grant from the U.S. Department of Energy.

  2. Evaluating Henry's law constant of N-nitrosodimethylamine (NDMA).

    PubMed

    Haruta, Shinsuke; Jiao, Wentao; Chen, Weiping; Chang, Andrew C; Gan, Jay

    2011-01-01

    N-Nitrosodimethylamine (NDMA), a potential carcinogen, may contaminate the groundwater when the reclaimed wastewater is used for irrigation and groundwater recharge. Henry's law constant is a critical parameter to assess the fate and transport of reclaimed wastewater-borne NDMA in the soil profile. We conducted a laboratory experiment in which the change of NDMA concentration in water exposed to the atmosphere was measured with respect to time and, based on the data, obtained the dimensionless Henry's law constant (K(H)') of NDMA, at 1.0 x 10(-4). The K(H)' suggests that NDMA has a relatively high potential to volatilize in the field where NDMA-containing wastewater is used for irrigation and the volatilization loss may be a significant pathway of NDMA transport. The experiment was based on the two boundary-layer approach of mass transfer at the atmosphere-water interface. It is an expedient method to delineate K(H)' for volatile or semi-volatile compounds present in water at low concentrations.

  3. Evaluation of constant current alternating current iontophoresis for transdermal drug delivery.

    PubMed

    Yan, Guang; Li, S Kevin; Higuchi, William I

    2005-12-10

    Previous studies in our laboratory have demonstrated that alternating current (AC) iontophoresis can significantly decrease skin electric resistance and enhance the transport of charged permeants across skin. Flux variability of neutral permeants during AC iontophoresis was also found to be less than that of conventional direct current (DC) iontophoresis. The objectives of the present study were to evaluate flux enhancement of constant current AC transdermal iontophoresis and compare the AC flux with that of constant current DC iontophoresis. Iontophoresis studies of AC amplitude of 1, 2, and 5 mA were conducted in side-by-side diffusion cells with donor solution of 0.015, 0.15, and 1.0 M tetraethylammonium (TEA) chloride and receiver solution of phosphate buffered saline (PBS) using human epidermal membrane (HEM). Conventional constant current DC iontophoresis of 0.2 mA was also performed under similar conditions. TEA and mannitol were the model permeants. The following are the major findings in the present study. The flux of TEA increased proportionally with the AC current for all three TEA chloride concentrations and at the AC frequency used in the present study. When the permeant and its counter ion were the only ionic species in the donor chamber, the fluxes during DC iontophoresis were weakly dependent of its donor concentration. The fluxes of TEA during constant current AC iontophoresis were moderately related to the donor concentration with the highest TEA flux observed under the 1.0 M TEA chloride condition although the relationship between flux and donor concentration was not linear. A trend of decreasing electroosmotic transport with increasing donor TEA chloride concentration was observed with significant sample-to-sample variability during DC iontophoresis. Mannitol permeability was also observed to decrease with increasing TEA chloride concentration in the donor under the AC conditions, but data variability under AC was significantly smaller than that

  4. Finite-Temperature Behavior of PdH x Elastic Constants Computed by Direct Molecular Dynamics

    DOE PAGES

    Zhou, X. W.; Heo, T. W.; Wood, B. C.; ...

    2017-05-30

    In this paper, robust time-averaged molecular dynamics has been developed to calculate finite-temperature elastic constants of a single crystal. We find that when the averaging time exceeds a certain threshold, the statistical errors in the calculated elastic constants become very small. We applied this method to compare the elastic constants of Pd and PdH 0.6 at representative low (10 K) and high (500 K) temperatures. The values predicted for Pd match reasonably well with ultrasonic experimental data at both temperatures. In contrast, the predicted elastic constants for PdH 0.6 only match well with ultrasonic data at 10 K; whereas, atmore » 500 K, the predicted values are significantly lower. We hypothesize that at 500 K, the facile hydrogen diffusion in PdH 0.6 alters the speed of sound, resulting in significantly reduced values of predicted elastic constants as compared to the ultrasonic experimental data. Finally, literature mechanical testing experiments seem to support this hypothesis.« less

  5. General relativity with small cosmological constant from spontaneous compactification of Lovelock theory in vacuum

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

    Canfora, Fabrizio; Willison, Steven; Giacomini, Alex

    2009-08-15

    It is shown that Einstein gravity in four dimensions with small cosmological constant and small extra dimensions can be obtained by spontaneous compactification of Lovelock gravity in vacuum. Assuming that the extra dimensions are compact spaces of constant curvature, general relativity is recovered within a certain class of Lovelock theories possessing necessarily cubic or higher order terms in curvature. This bounds the higher dimension to at least 7. Remarkably, the effective gauge coupling and Newton constant in four dimensions are not proportional to the gravitational constant in higher dimensions, but are shifted with respect to their standard values. This effectmore » opens up new scenarios where a maximally symmetric solution in higher dimensions could decay into the compactified spacetime either by tunneling or through a gravitational analog of ghost condensation. Indeed, this is what occurs requiring both the extra dimensions and the four-dimensional cosmological constant to be small.« less

  6. The cosmological constant and dark energy

    NASA Astrophysics Data System (ADS)

    Peebles, P. J.; Ratra, Bharat

    2003-04-01

    Physics welcomes the idea that space contains energy whose gravitational effect approximates that of Einstein’s cosmological constant, Λ; today the concept is termed dark energy or quintessence. Physics also suggests that dark energy could be dynamical, allowing for the arguably appealing picture of an evolving dark-energy density approaching its natural value, zero, and small now because the expanding universe is old. This would alleviate the classical problem of the curious energy scale of a millielectron volt associated with a constant Λ. Dark energy may have been detected by recent cosmological tests. These tests make a good scientific case for the context, in the relativistic Friedmann-Lemaître model, in which the gravitational inverse-square law is applied to the scales of cosmology. We have well-checked evidence that the mean mass density is not much more than one-quarter of the critical Einstein de Sitter value. The case for detection of dark energy is not yet as convincing but still serious; we await more data, which may be derived from work in progress. Planned observations may detect the evolution of the dark-energy density; a positive result would be a considerable stimulus for attempts at understanding the microphysics of dark energy. This review presents the basic physics and astronomy of the subject, reviews the history of ideas, assesses the state of the observational evidence, and comments on recent developments in the search for a fundamental theory.

  7. On the Henry constant and isosteric heat at zero loading in gas phase adsorption.

    PubMed

    Do, D D; Nicholson, D; Do, H D

    2008-08-01

    The Henry constant and the isosteric heat of adsorption at zero loading are commonly used as indicators of the strength of the affinity of an adsorbate for a solid adsorbent. It is assumed that (i) they are observable in practice, (ii) the Van Hoff's plot of the logarithm of the Henry constant versus the inverse of temperature is always linear and the slope is equal to the heat of adsorption, and (iii) the isosteric heat of adsorption at zero loading is either constant or weakly dependent on temperature. We show in this paper that none of these three points is necessarily correct, first because these variables might not be observable since they are outside the range of measurability; second that the linearity of the Van Hoff plot breaks down at very high temperature, and third that the isosteric heat versus loading is a strong function of temperature. We demonstrate these points using Monte Carlo integration and Monte Carlo simulation of adsorption of various gases on a graphite surface. Another issue concerning the Henry constant is related to the way the adsorption excess is defined. The most commonly used equation is the one that assumes that the void volume is the volume extended all the way to a boundary passing through the centres of the outermost solid atoms. With this definition the Henry constant can become negative at high temperatures. Although adsorption at these temperatures may not be practical because of the very low value of the Henry constant, it is more useful to define the Henry constant in such a way that it is always positive at all temperatures. Here we propose the use of the accessible volume; the volume probed by the adsorbate when it is in nonpositive regions of the potential, to calculate the Henry constant.

  8. Growth rate and trapping efficacy of nematode-trapping fungi under constant and fluctuating temperatures.

    PubMed

    Fernández, A S; Larsen, M; Wolstrup, J; Grønvold, J; Nansen, P; Bjørn, H

    1999-08-01

    The effect of temperature on radial growth and predatory activity of different isolates of nematode-trapping fungi was assessed. Four isolates of Duddingtonia flagrans and one isolate of Arthrobotrys oligospora were inoculated on petri dishes containing either cornmeal agar (CMA) or faecal agar and then incubated for 14 days under three different constant and fluctuating temperature regimes. The radial growth was similar on the two substrates at each temperature regime. All fungal isolates showed a higher growth rate at a constant 20 degrees C. At 10 degrees and 15 degrees C, all D. flagrans isolates showed very similar patterns of radial growth at both constant and fluctuating temperatures. At 20 degrees C, they grew significantly faster at constant than at fluctuating temperatures. A. oligospora grew significantly faster than all D. flagrans isolates except when incubated at a fluctuating 20 degrees C. Spores of each fungal isolate were added to faecal cultures containing eggs of Cooperia oncophora at a concentration of 6250 spores/g faeces. The cultures were incubated for 14 days at the same temperature regimes described above. Control faeces (without fungal material) were also cultured. More larvae were recovered from the fungus-treated cultures incubated at a constant 10 degrees or 15 degrees C than from those incubated at the respective fluctuating temperatures, except for one D. flagrans isolate. Incubation at 20 degrees C showed the opposite effect. The general reduction observed in the number of nematode larvae due to fungal trapping was 18-25% and 48-80% for a constant and fluctuating 10 degrees C, 70-96% and 93-95% for a constant and fluctuating 15 degrees C, and 63-98% and 0-25% for a constant and fluctuating 20 degrees C, respectively.

  9. Constant-intensity waves and their modulation instability in non-Hermitian potentials

    NASA Astrophysics Data System (ADS)

    Makris, K. G.; Musslimani, Z. H.; Christodoulides, D. N.; Rotter, S.

    2015-07-01

    In all of the diverse areas of science where waves play an important role, one of the most fundamental solutions of the corresponding wave equation is a stationary wave with constant intensity. The most familiar example is that of a plane wave propagating in free space. In the presence of any Hermitian potential, a wave's constant intensity is, however, immediately destroyed due to scattering. Here we show that this fundamental restriction is conveniently lifted when working with non-Hermitian potentials. In particular, we present a whole class of waves that have constant intensity in the presence of linear as well as of nonlinear inhomogeneous media with gain and loss. These solutions allow us to study the fundamental phenomenon of modulation instability in an inhomogeneous environment. Our results pose a new challenge for the experiments on non-Hermitian scattering that have recently been put forward.

  10. Cosmic acceleration in the nonlocal approach to the cosmological constant problem

    NASA Astrophysics Data System (ADS)

    Oda, Ichiro

    2018-04-01

    We have recently constructed a manifestly local formulation of a nonlocal approach to the cosmological constant problem which can treat with quantum effects from both matter and gravitational fields. In this formulation, it has been explicitly shown that the effective cosmological constant is radiatively stable even in the presence of the gravitational loop effects. Since we are naturally led to add the R^2 term and the corresponding topological action to an original action, we make use of this formulation to account for the late-time acceleration of expansion of the universe in case of the open universes with infinite space-time volume. We will see that when the "scalaron", which exists in the R^2 gravity as an extra scalar field, has a tiny mass of the order of magnitude {O}(1 meV), we can explain the current value of the cosmological constant in a consistent manner.

  11. Rationalizing 5000-Fold Differences in Receptor-Binding Rate Constants of Four Cytokines

    PubMed Central

    Pang, Xiaodong; Qin, Sanbo; Zhou, Huan-Xiang

    2011-01-01

    The four cytokines erythropoietin (EPO), interleukin-4 (IL4), human growth hormone (hGH), and prolactin (PRL) all form four-helix bundles and bind to type I cytokine receptors. However, their receptor-binding rate constants span a 5000-fold range. Here, we quantitatively rationalize these vast differences in rate constants by our transient-complex theory for protein-protein association. In the transient complex, the two proteins have near-native separation and relative orientation, but have yet to form the short-range specific interactions of the native complex. The theory predicts the association rate constant as ka=ka0exp(−ΔGel∗/kBT) where ka0 is the basal rate constant for reaching the transient complex by random diffusion, and the Boltzmann factor captures the rate enhancement due to electrostatic attraction. We found that the vast differences in receptor-binding rate constants of the four cytokines arise mostly from the differences in charge complementarity among the four cytokine-receptor complexes. The basal rate constants (ka0) of EPO, IL4, hGH, and PRL were similar (5.2 × 105 M−1s−1, 2.4 × 105 M−1s−1, 1.7 × 105 M−1s−1, and 1.7 × 105 M−1s−1, respectively). However, the average electrostatic free energies (ΔGe1∗) were very different (−4.2 kcal/mol, −2.4 kcal/mol, −0.1 kcal/mol, and −0.5 kcal/mol, respectively, at ionic strength = 160 mM). The receptor-binding rate constants predicted without adjusting any parameters, 6.2 × 108 M−1s−1, 1.3 × 107 M−1s−1, 2.0 × 105 M−1s−1, and 7.6 × 104 M−1s−1, respectively, for EPO, IL4, hGH, and PRL agree well with experimental results. We uncover that these diverse rate constants are anticorrelated with the circulation concentrations of the cytokines, with the resulting cytokine-receptor binding rates very close to the limits set by the half-lives of the receptors, suggesting that these binding rates are functionally relevant and perhaps evolutionarily

  12. Evaluation of uncertainty in the adjustment of fundamental constants

    NASA Astrophysics Data System (ADS)

    Bodnar, Olha; Elster, Clemens; Fischer, Joachim; Possolo, Antonio; Toman, Blaza

    2016-02-01

    Combining multiple measurement results for the same quantity is an important task in metrology and in many other areas. Examples include the determination of fundamental constants, the calculation of reference values in interlaboratory comparisons, or the meta-analysis of clinical studies. However, neither the GUM nor its supplements give any guidance for this task. Various approaches are applied such as weighted least-squares in conjunction with the Birge ratio or random effects models. While the former approach, which is based on a location-scale model, is particularly popular in metrology, the latter represents a standard tool used in statistics for meta-analysis. We investigate the reliability and robustness of the location-scale model and the random effects model with particular focus on resulting coverage or credible intervals. The interval estimates are obtained by adopting a Bayesian point of view in conjunction with a non-informative prior that is determined by a currently favored principle for selecting non-informative priors. Both approaches are compared by applying them to simulated data as well as to data for the Planck constant and the Newtonian constant of gravitation. Our results suggest that the proposed Bayesian inference based on the random effects model is more reliable and less sensitive to model misspecifications than the approach based on the location-scale model.

  13. 18 CFR 806.12 - Constant-rate aquifer testing.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... groundwater availability analysis to determine the availability of water during a 1-in-10-year recurrence... 18 Conservation of Power and Water Resources 2 2010-04-01 2010-04-01 false Constant-rate aquifer testing. 806.12 Section 806.12 Conservation of Power and Water Resources SUSQUEHANNA RIVER BASIN...

  14. Experimental and Estimated Rate Constants for the Reactions of Hydroxyl Radicals with Several Halocarbons

    NASA Technical Reports Server (NTRS)

    DeMore, W.B.

    1996-01-01

    Relative rate experiments are used to measure rate constants and temperature dependencies of the reactions of OH with CH3F (41), CH2FCl (31), CH2BrCl (30B1), CH2Br2 (3OB2), CHBr3 (2OB3), CF2BrCHFCl (123aBl(alpha)), and CF2ClCHCl2 (122). Rate constants for additional compounds of these types are estimated using an empirical rate constant estimation method which is based on measured rate constants for a wide range of halocarbons. The experimental data are combined with the estimated and previously reported rate constants to illustrate the effects of F, Cl, and Br substitution on OH rate constants for a series of 19 halomethanes and 25 haloethanes. Application of the estimation technique is further illustrated for some higher hydrofluorocarbons (HFCs), including CHF2CF2CF2CF2H (338pcc), CF3CHFCHFCF2CF3 (43-10mee), CF3CH2CH2CF3 (356ffa), CF3CH2CF2CH2CF3 (458mfcf), CF3CH2CHF2 (245fa), and CF3CH2CF2CH3 (365mfc). The predictions are compared with literature data for these compounds.

  15. Elastic constants of hcp 4He: Path-integral Monte Carlo results versus experiment

    NASA Astrophysics Data System (ADS)

    Ardila, Luis Aldemar Peña; Vitiello, Silvio A.; de Koning, Maurice

    2011-09-01

    The elastic constants of hcp 4He are computed using the path-integral Monte Carlo (PIMC) method. The stiffness coefficients are obtained by imposing different distortions to a periodic cell containing 180 atoms, followed by measurement of the elements of the corresponding stress tensor. For this purpose an appropriate path-integral expression for the stress tensor observable is derived and implemented into the pimc++ package. In addition to allowing the determination of the elastic stiffness constants, this development also opens the way to an explicit atomistic determination of the Peierls stress for dislocation motion using the PIMC technique. A comparison of the results to available experimental data shows an overall good agreement of the density dependence of the elastic constants, with the single exception of C13. Additional calculations for the bcc phase, on the other hand, show good agreement for all elastic constants.

  16. Cosmological constant problem and renormalized vacuum energy density in curved background

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

    Kohri, Kazunori; Matsui, Hiroki, E-mail: kohri@post.kek.jp, E-mail: matshiro@post.kek.jp

    The current vacuum energy density observed as dark energy ρ{sub dark}≅ 2.5×10{sup −47} GeV{sup 4} is unacceptably small compared with any other scales. Therefore, we encounter serious fine-tuning problem and theoretical difficulty to derive the dark energy. However, the theoretically attractive scenario has been proposed and discussed in literature: in terms of the renormalization-group (RG) running of the cosmological constant, the vacuum energy density can be expressed as ρ{sub vacuum}≅ m {sup 2} H {sup 2} where m is the mass of the scalar field and rather dynamical in curved spacetime. However, there has been no rigorous proof to derivemore » this expression and there are some criticisms about the physical interpretation of the RG running cosmological constant. In the present paper, we revisit the RG running effects of the cosmological constant and investigate the renormalized vacuum energy density in curved spacetime. We demonstrate that the vacuum energy density described by ρ{sub vacuum}≅ m {sup 2} H {sup 2} appears as quantum effects of the curved background rather than the running effects of cosmological constant. Comparing to cosmological observational data, we obtain an upper bound on the mass of the scalar fields to be smaller than the Planck mass, m ∼< M {sub Pl}.« less

  17. Current observations with a decaying cosmological constant allow for chaotic cyclic cosmology

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

    Ellis, George F.R.; Platts, Emma; Weltman, Amanda

    2016-04-01

    We use the phase plane analysis technique of Madsen and Ellis [1] to consider a universe with a true cosmological constant as well as a cosmological 'constant' that is decaying. Time symmetric dynamics for the inflationary era allows eternally bouncing models to occur. Allowing for scalar field dynamic evolution, we find that if dark energy decays in the future, chaotic cyclic universes exist provided the spatial curvature is positive. This is particularly interesting in light of current observations which do not yet rule out either closed universes or possible evolution of the cosmological constant. We present only a proof ofmore » principle, with no definite claim on the physical mechanism required for the present dark energy to decay.« less

  18. Extracting Diffusion Constants from Echo-Time-Dependent PFG NMR Data Using Relaxation-Time Information

    NASA Astrophysics Data System (ADS)

    Vandusschoten, D.; Dejager, P. A.; Vanas, H.

    Heterogeneous (bio)systems are often characterized by several water-containing compartments that differ in relaxation time values and diffusion constants. Because of the relatively small differences among these diffusion constants, nonoptimal measuring conditions easily lead to the conclusion that a single diffusion constant suffices to describe the water mobility in a heterogeneous (bio)system. This paper demonstrates that the combination of a T2 measurement and diffusion measurements at various echo times (TE), based on the PFG MSE sequence, enables the accurate determination of diffusion constants which are less than a factor of 2 apart. This new method gives errors of the diffusion constant below 10% when two fractions are present, while the standard approach of a biexponential fit to the diffusion data in identical circumstances gives larger (>25%) errors. On application of this approach to water in apple parenchyma tissue, the diffusion constant of water in the vacuole of the cells ( D = 1.7 × 10 -9 m 2/s) can be distinguished from that of the cytoplasm ( D = 1.0 × 10 -9 m 2/s). Also, for mung bean seedlings, the cell size determined by PFG MSE measurements increased from 65 to 100 μm when the echo time increased from 150 to 900 ms, demonstrating that the interpretation of PFG SE data used to investigate cell sizes is strongly dependent on the T2 values of the fractions within the sample. Because relaxation times are used to discriminate the diffusion constants, we propose to name this approach diffusion analysis by relaxation- time- separated (DARTS) PFG NMR.

  19. A Constant Pressure Bomb

    NASA Technical Reports Server (NTRS)

    Stevens, F W

    1924-01-01

    This report describes a new optical method of unusual simplicity and of good accuracy suitable to study the kinetics of gaseous reactions. The device is the complement of the spherical bomb of constant volume, and extends the applicability of the relationship, pv=rt for gaseous equilibrium conditions, to the use of both factors p and v. The method substitutes for the mechanical complications of a manometer placed at some distance from the seat of reaction the possibility of allowing the radiant effects of reaction to record themselves directly upon a sensitive film. It is possible the device may be of use in the study of the photoelectric effects of radiation. The method makes possible a greater precision in the measurement of normal flame velocities than was previously possible. An approximate analysis shows that the increase of pressure and density ahead of the flame is negligible until the velocity of the flame approaches that of sound.

  20. PLZT capacitor and method to increase the dielectric constant

    DOEpatents

    Taylor, Ralph S.; Fairchild, Manuel Ray; Balachjandran, Uthamalingam; Lee, Tae H.

    2017-12-12

    A ceramic-capacitor includes a first electrically-conductive-layer, a second electrically-conductive-layer arranged proximate to the first electrically-conductive-layer, and a dielectric-layer interposed between the first electrically-conductive-layer and the second electrically-conductive-layer. The dielectric-layer is formed of a lead-lanthanum-zirconium-titanate material (PLZT), wherein the PLZT is characterized by a dielectric-constant greater than 125, when measured at 25 degrees Celsius and zero Volts bias, and an excitation frequency of ten-thousand Hertz (10 kHz). A method for increasing a dielectric constant of the lead-lanthanum-zirconium-titanate material (PLZT) includes the steps of depositing PLZT to form a dielectric-layer of a ceramic-capacitor, and heating the ceramic-capacitor to a temperature not greater than 300.degree. C.