Science.gov

Sample records for activation time constants

  1. Active imaging lens with real-time variable resolution and constant field of view

    NASA Astrophysics Data System (ADS)

    Parent, Jocelyn; Thibault, Simon

    2010-08-01

    We present a lens with a constant total field of view and real-time variable resolution in certain zones of interest. This smart imaging lens uses an active optical element to modify as desired the local distortion. This way, while keeping the total field of view constant, the resolution can be increased in a zone of interest, at the expense of decreasing it somewhere in the remaining part of the field of view. We first present the concept of this lens, using a deformable mirror as the active surface. Computer simulations are done with Zemax in which a magnifying power of 2 in a zone of interest representing 10% of the full field of view is achieved, using a f=12.5 mm lens and a F/# of 18. Different combinations of theses parameters would allow different performances and results. We then present experimental results of this lens with a prototype built using a ferrofluidic deformable mirror as the active element. Experimental results of a zone of increased resolution with a magnification of 1.32 and a zone of decreased resolution with a magnification of 0.80 are obtained.

  2. Time-Varying Fundamental Constants

    NASA Astrophysics Data System (ADS)

    Olive, Keith

    2003-04-01

    Recent data from quasar absorption systems can be interpreted as arising from a time variation in the fine-structure constant. However, there are numerous cosmological, astro-physical, and terrestrial bounds on any such variation. These includes bounds from Big Bang Nucleosynthesis (from the ^4He abundance), the Oklo reactor (from the resonant neutron capture cross-section of Sm), and from meteoretic lifetimes of heavy radioactive isotopes. The bounds on the variation of the fine-structure constant are significantly strengthened in models where all gauge and Yukawa couplings vary in a dependent manner, as would be expected in unified theories. Models which are consistent with all data are severly challenged when Equivalence Principle constraints are imposed.

  3. Effect of coil orientation on strength–duration time constant and I-wave activation with controllable pulse parameter transcranial magnetic stimulation

    PubMed Central

    D’Ostilio, Kevin; Goetz, Stefan M.; Hannah, Ricci; Ciocca, Matteo; Chieffo, Raffaella; Chen, Jui-Cheng A.; Peterchev, Angel V.; Rothwell, John C.

    2016-01-01

    Objective To compare the strength–duration (S–D) time constants of motor cortex structures activated by current pulses oriented posterior–anterior (PA) or anterior–posterior (AP) across the central sulcus. Methods Motor threshold and input–output curve, along with motor evoked potential (MEP) latencies, of first dorsal interosseus were determined at pulse widths of 30, 60, and 120 μs using a controllable pulse parameter (cTMS) device, with the coil oriented PA or AP. These were used to estimate the S–D time constant and we compared with data for responses evoked by cTMS of the ulnar nerve at the elbow. Results The S–D time constant with PA was shorter than for AP stimulation (230.9 ± 97.2 vs. 294.2 ± 90.9 μs; p < 0.001). These values were similar to those calculated after stimulation of ulnar nerve (197 ± 47 μs). MEP latencies to AP, but not PA stimulation were affected by pulse width, showing longer latencies following short duration stimuli. Conclusion PA and AP stimuli appear to activate the axons of neurons with different time constants. Short duration AP pulses are more selective than longer pulses in recruiting longer latency corticospinal output. Significance More selective stimulation of neural elements may be achieved by manipulating pulse width and orientation. PMID:26077634

  4. 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…

  5. Time constants of flat superconducting cables

    SciTech Connect

    Takacs, S.; Yamamoto, J.

    1997-06-01

    The frequency dependence of coupling losses is calculated for flat superconducting cables, including the electromagnetic coupling between different current loops on the cable. It is shown that there are two characteristic time constants for both parallel and transverse coupling losses. The values of these time constants {tau}{sub 0} and {tau}{sub 1} are calculated by introducing effective inductances for the current loops. In both cases, {tau}{sub 1} is considerably smaller than {tau}{sub 0}. As the most important methods of determining {tau}{sub 0} from AC losses - namely, the limiting slope of loss/cycle at zero frequency and the position of the maximum loss/cycle vs. frequency - estimate {tau}{sub 0} and {tau}{sub 1}, respectively, the results are important for practical measurements and evaluation of time constants from AC losses. At larger frequencies, the losses are more likely to those in normal conductors (skin effect). The calculation schemes can be applied to cables with closely wound strands (like the cable-in-conduit conductors), too. However, several other effects should be considered being different and/or more important with respect to other cable types (demagnetization factor of strands and cables, larger regions near the cable edges, smaller number of strands and subcables, etc.).

  6. Ventricular fibrillation time constant for swine.

    PubMed

    Wu, Jiun-Yan; Nimunkar, Amit J; Sun, Hongyu; O'Rourke, Ann; Huebner, Shane; Will, James A; Webster, John G

    2008-10-01

    The strength-duration curve for cardiac excitation can be modeled by a parallel resistor-capacitor circuit that has a time constant. Experiments on six pigs were performed by delivering current from the X26 Taser dart at a distance from the heart to cause ventricular fibrillation (VF). The X26 Taser is an electromuscular incapacitation device (EMD), which generates about 50 kV and delivers a pulse train of about 15-19 pulses s(-1) with a pulse duration of about 150 micros and peak current about 2 A. Similarly a continuous 60 Hz alternating current of the amplitude required to cause VF was delivered from the same distance. The average current and duration of the current pulse were estimated in both sets of experiments. The strength-duration equation was solved to yield an average time constant of 2.87 ms +/- 1.90 (SD). Results obtained may help in the development of safety standards for future electromuscular incapacitation devices (EMDs) without requiring additional animal tests.

  7. Measuring the RC time constant with Arduino

    NASA Astrophysics Data System (ADS)

    Pereira, N. S. A.

    2016-11-01

    In this work we use the Arduino UNO R3 open source hardware platform to assemble an experimental apparatus for the measurement of the time constant of an RC circuit. With adequate programming, the Arduino is used as a signal generator, a data acquisition system and a basic signal visualisation tool. Theoretical calculations are compared with direct observations from an analogue oscilloscope. Data processing and curve fitting is performed on a spreadsheet. The results obtained for the six RC test circuits are within the expected interval of values defined by the tolerance of the components. The hardware and software prove to be adequate to the proposed measurements and therefore adaptable to a laboratorial teaching and learning context.

  8. Time constant of the cerebral arterial bed in normal subjects.

    PubMed

    Kasprowicz, Magdalena; Diedler, Jennifer; Reinhard, Matthias; Carrera, Emmanuel; Steiner, Luzius A; Smielewski, Peter; Budohoski, Karol P; Haubrich, Christina; Pickard, John D; Czosnyka, Marek

    2012-07-01

    The time constant of cerebral arterial bed (in brief time constant) is a product of brain arterial compliance (C(a)) and resistance (CVR). We tested the hypothesis that in normal subjects, changes in end-tidal CO(2) (EtCO(2)) affect the value of the time constant. C(a) and CVR were estimated using mathematical transformations of arterial pressure (ABP) and transcranial Doppler (TCD) cerebral blood flow velocity waveforms. Responses of the time constant to controlled changes in EtCO(2) were compared in 34 young volunteers. Hypercapnia shortened the time constant (0.22 s [0.17, 0.26] vs. 0.16 s [0.13, 0.20]; p = 0.000001), while hypocapnia lengthened the time constant (0.22 s [0.17, 0.26] vs. 0.23 s [0.19, 0.32]; p < 0.0032). The time constant was negatively correlated with changes in EtCO(2) (R(partial) = -0.68, p < 0.000001). This was associated with a decrease in CVR when EtCO(2) increased (R(partial) = -0.80, p < 0.000001) and C(a) remained independent of changes in EtCO(2). C(a) was negatively correlated with mean ABP (R(partial) = -0.68, p < 0.000001). In summary, the time constant shortens with increasing EtCO(2). Its potential role in cerebrovascular investigations needs further studies.

  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. Time optimal paths for a constant speed unicycle

    SciTech Connect

    Reister, D.B.

    1991-01-01

    This paper uses the Pontryagin maximum principle to find time optimal paths for a constant speed unicycle. The time optimal paths consist of sequences of arcs of circles and straight lines. The maximum principle introduced concepts (dual variables, bang-bang solutions, singular solutions, and transversality conditions) that provide important insight into the nature of the time optimal paths. 10 refs., 6 figs.

  11. Scattering in an external electric field asymptotically constant in time

    SciTech Connect

    Adachi, Tadayoshi; Ishida, Atsuhide

    2011-06-15

    We show the asymptotic completeness for two-body quantum systems in an external electric field asymptotically non-zero constant in time. One of the main ingredients of this paper is to give some propagation estimates for physical propagators generated by time-dependent Hamiltonians which govern the systems under consideration.

  12. Early universe constraints on time variation of fundamental constants

    SciTech Connect

    Landau, Susana J.; Mosquera, Mercedes E.; Scoccola, Claudia G.; Vucetich, Hector

    2008-10-15

    We study the time variation of fundamental constants in the early Universe. Using data from primordial light nuclei abundances, cosmic microwave background, and the 2dFGRS power spectrum, we put constraints on the time variation of the fine structure constant {alpha} and the Higgs vacuum expectation value without assuming any theoretical framework. A variation in leads to a variation in the electron mass, among other effects. Along the same line, we study the variation of {alpha} and the electron mass m{sub e}. In a purely phenomenological fashion, we derive a relationship between both variations.

  13. Correction for instrument time constant in determination of reaction kinetics.

    SciTech Connect

    Chilton, Marie; Clark, Jared; Thomas, Nathan; Nicholson, Allen; Hansen, Lee D.; Hansen, Clifford W.; Hansen, Jaron

    2010-02-01

    Rates of reactions can be expressed as dn/dt = kcf(n) where n is moles of reaction, k is a rate constant, c is a proportionality constant, and f(n) is a function of the properties of the sample. When the instrument time constant, ?, and k are sufficiently comparable that measured rates are significantly affected by instrument response, correction for instrument response must be done to obtain accurate reaction kinetics. Correction for instrument response has previously been done by truncating early data or by use of the Tian equation. Both methods can lead to significant errors. We describe a method for simultaneous determination of ?, k, and c by fitting equations describing the combined instrument response and rate law to rates observed as a function of time. The method was tested with data on the heat rate from acid-catalyzed hydrolysis of sucrose.

  14. The cosmological constant problem and re-interpretation of time

    NASA Astrophysics Data System (ADS)

    Luo, M. J.

    2014-07-01

    We abandon the interpretation that time is a global parameter in quantum mechanics, replace it by a quantum dynamical variable playing the role of time. This operational re-interpretation of time provides a solution to the cosmological constant problem. The expectation value of the zero-point energy under the new time variable vanishes. The fluctuation of the vacuum energy as the leading contribution to the gravitational effect gives a correct order to the observed "dark energy". The "dark energy" as a mirage is always seen comparable with the matter energy density by an observer using the internal clock time. Conceptual consequences of the re-interpretation of time are also discussed.

  15. Testing Theories That Predict Time Variation of Fundamental Constants

    NASA Astrophysics Data System (ADS)

    Landau, Susana J.; Vucetich, Hector

    2002-05-01

    We consider astronomical and local bounds on the time variation of fundamental constants to test some generic Kaluza-Klein-like models and some particular cases of Beckenstein theory. Bounds on the free parameters of the different theories are obtained. Furthermore, we find that none of the proposed models is able to explain recent results (as from Webb and coworkers in 1999 and 2001) claiming an observed variation of the fine-structure constant from quasar absorption systems at redshifts 0.5

  16. 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.

  17. Computing classically exact diffusion constants using short-time trajectories

    SciTech Connect

    Voter, A. F.

    1989-07-10

    The classical diffusion constant of a point defect in an infinite lattice of binding sites is shown to be expressible as transition-state-theory rates multiplied by dynamical correction factors computed from short-time classical trajectories initiated at the site boundaries. The expression, which results from time differentiating the lattice-discretized mean-square displacement, is valid at any temperature for which the site lattice is well defined. It thus avoids both the time-scale limitations of direct molecular dynamics and the rare-event requirements of standard dynamical-correction methods.

  18. New method of measuring the thermal time constant of junction lasers

    SciTech Connect

    Fujita, O.

    1985-02-01

    A new method of measuring the thermal time constant of a junction laser's active region by using the output light power frequency response is presented. The thermal time constant tau can be calculated from the maximum value of the phase shift which is measured at a lower frequency than the cutoff frequency (1/2..pi..tau). This method is highly suitable for use under high drive current and/or high temperature conditions.

  19. Time Varying Gravitational Constant G via Entropic Force

    NASA Astrophysics Data System (ADS)

    M. R., Setare; Momeni, D.

    2011-10-01

    If the uncertainty principle applies to the Verlinde entropic idea, it leads to a new term in the Newton's second law of mechanics in the Planck's scale. This curious velocity dependent term inspires a frictional feature of the gravity In this short letter we address that this new term modifies the effective mass and the Newtonian constant as the time dependent quantities. Thus we must have a running on the value of the effective mass on the particle mass m near the holographic screen and the G. This result has a nigh relation with the Dirac hypothesis about the large numbers hypothesis (L.N.H.). We propose that the corrected entropic terms via Verlinde idea can be brought as a holographic evidence for the authenticity of the Dirac idea.

  20. Influence of a constant magnetic field on thrombocytes. [delay of blood coagulation time

    NASA Technical Reports Server (NTRS)

    Meyerova, Y. A.

    1974-01-01

    In an experiment on white mice it was found that a constant electromagnetic field with strength of 250-275 oersteds is biologically active at an exposure of 55 minutes. Qualitative and morphological changes in thrombocytes 1-3 days following exposure reduced their numbers, prolonged blood coagulation time and increased the number of leucocytes.

  1. Minimizing the area required for time constants in integrated circuits

    NASA Technical Reports Server (NTRS)

    Lyons, J. C.

    1972-01-01

    When a medium- or large-scale integrated circuit is designed, efforts are usually made to avoid the use of resistor-capacitor time constant generators. The capacitor needed for this circuit usually takes up more surface area on the chip than several resistors and transistors. When the use of this network is unavoidable, the designer usually makes an effort to see that the choice of resistor and capacitor combinations is such that a minimum amount of surface area is consumed. The optimum ratio of resistance to capacitance that will result in this minimum area is equal to the ratio of resistance to capacitance which may be obtained from a unit of surface area for the particular process being used. The minimum area required is a function of the square root of the reciprocal of the products of the resistance and capacitance per unit area. This minimum occurs when the area required by the resistor is equal to the area required by the capacitor.

  2. Is the possible fine-structure constant drift also a test of a time-dependent Planck constant?

    NASA Astrophysics Data System (ADS)

    Öztas, A. M.; Smith, M. L.

    2011-12-01

    The recent publication of spatial and distance variation of the fine-structure constant, α, derived from astronomical data of quasar emissions (QE) is exciting. The decreasing value of α over time, derived from data obtained from the Very Large Telescope (VLT) in Chile, encourages the search for other possible running constants. We surmise that emissions from distant supernovae, type Ia (SNe Ia), which are more blue than predictions are best explained by a decreasing Planck constant with increasing lookback time. We present some results from our theoretical work and comparison to the astronomical observations and suggest that both α and h might be running constants. More data are required to answer several questions about the origin of the "drifting" α and the possible time dependence of h. Astronomical tools such as SNe and QE may be the best means to secure the exacting data needed to confirm or deny these hypotheses.

  3. Time variation of the fine structure constant driven by quintessence

    NASA Astrophysics Data System (ADS)

    Anchordoqui, Luis; Goldberg, Haim

    2003-10-01

    There are indications from the study of quasar absorption spectra that the fine structure constant α may have been measurably smaller for redshifts z>2. Analyses of other data (149Sm fission rate for the Oklo natural reactor, variation of 187Re β-decay rate in meteorite studies, atomic clock measurements) which probe variations of α in the more recent past imply much smaller deviations from its present value. In this work we tie the variation of α to the evolution of the quintessence field proposed by Albrecht and Skordis, and show that agreement with all these data, as well as consistency with Wilkinson Microwave Anisotropy Probe observations, can be achieved for a range of parameters. Some definite predictions follow for upcoming space missions searching for violations of the equivalence principle.

  4. Measurement of sodium fluorescein wash-in time constants in subjects with peripheral vascular disease.

    PubMed

    Oh, D K; Zhang, A; Magin, R L

    1997-01-01

    The authors developed a noninvasive two-channel dynamic dermofluorometer that can quantitatively follow the rapid skin wash-in kinetics of a fluorescent dye to provide an assessment of local skin perfusion. The dermofluorometer was tested in normal subjects and diabetic patients with and without peripheral vascular disease. After an intravenous injection of 1-2 mL of a 10% solution of sodium fluorescein (1.1-2.8 mg/kg), the fluorescent signal was monitored from two sites on the skin surfaces of the forearm and foot. A 3.2-mm-diameter glass fiberoptic bundle was used both to transmit the excitation light (489 nm) and to receive the fluorescent emission (517 nm). Dermofluorometer readings were recorded approximately every second for 10-15 minutes following the injection. The time course of the fluorescein signal intensity was fit to a single exponential curve characterized by a wash-in time constant. There was no significant difference in arm wash-in time constants. Foot wash-in time constants were increased in diabetic patients who had past histories of foot ulcers relative to diabetic patients without a history of foot ulcers (3.2 vs 1.6 min., p < 0.05). Foot wash-in time constants were decreased in diabetic patients who had active infected foot ulcers. This study demonstrates the ability of the dynamic dermofluorometer to measure wash-in constants that reflect the local skin perfusion in less than 15 minutes after a low intravenous dose of sodium fluorescein.

  5. A reservoir of time constants for memory traces in cortical neurons.

    PubMed

    Bernacchia, Alberto; Seo, Hyojung; Lee, Daeyeol; Wang, Xiao-Jing

    2011-03-01

    According to reinforcement learning theory of decision making, reward expectation is computed by integrating past rewards with a fixed timescale. In contrast, we found that a wide range of time constants is available across cortical neurons recorded from monkeys performing a competitive game task. By recognizing that reward modulates neural activity multiplicatively, we found that one or two time constants of reward memory can be extracted for each neuron in prefrontal, cingulate and parietal cortex. These timescales ranged from hundreds of milliseconds to tens of seconds, according to a power law distribution, which is consistent across areas and reproduced by a 'reservoir' neural network model. These neuronal memory timescales were weakly, but significantly, correlated with those of monkey's decisions. Our findings suggest a flexible memory system in which neural subpopulations with distinct sets of long or short memory timescales may be selectively deployed according to the task demands.

  6. Peptides of the Constant Region of Antibodies Display Fungicidal Activity

    PubMed Central

    Polonelli, Luciano; Ciociola, Tecla; Magliani, Walter; Zanello, Pier Paolo; D'Adda, Tiziana; Galati, Serena; De Bernardis, Flavia; Arancia, Silvia; Gabrielli, Elena; Pericolini, Eva; Vecchiarelli, Anna; Arruda, Denise C.; Pinto, Marcia R.; Travassos, Luiz R.; Pertinhez, Thelma A.; Spisni, Alberto; Conti, Stefania

    2012-01-01

    Synthetic peptides with sequences identical to fragments of the constant region of different classes (IgG, IgM, IgA) of antibodies (Fc-peptides) exerted a fungicidal activity in vitro against pathogenic yeasts, such as Candida albicans, Candida glabrata, Cryptococcus neoformans, and Malassezia furfur, including caspofungin and triazole resistant strains. Alanine-substituted derivatives of fungicidal Fc-peptides, tested to evaluate the critical role of each residue, displayed unaltered, increased or decreased candidacidal activity in vitro. An Fc-peptide, included in all human IgGs, displayed a therapeutic effect against experimental mucosal and systemic candidiasis in mouse models. It is intriguing to hypothesize that some Fc-peptides may influence the antifungal immune response and constitute the basis for devising new antifungal agents. PMID:22470523

  7. Time resolution studies using digital constant fraction discrimination

    NASA Astrophysics Data System (ADS)

    Fallu-Labruyere, A.; Tan, H.; Hennig, W.; Warburton, W. K.

    2007-08-01

    Digital Pulse Processing (DPP) modules are being increasingly considered to replace modular analog electronics in medium-scale nuclear physics experiments (100-1000s of channels). One major area remains, however, where it has not been convincingly demonstrated that DPP modules are competitive with their analog predecessors—time-of-arrival measurement. While analog discriminators and time-to-amplitude converters can readily achieve coincidence time resolutions in the 300-500 ps range with suitably fast scintillators and Photomultiplier Tubes (PMTs), this capability has not been widely demonstrated with DPPs. Some concern has been expressed, in fact, that such time resolutions are attainable with the 10 ns sampling times that are presently commonly available. In this work, we present time-coincidence measurements taken using a commercially available DPP (the Pixie-4 from XIA LLC) directly coupled to pairs of fast PMTs mated with either LSO or LaBr 3 scintillator crystals and excited by 22Na γ-ray emissions. Our results, 886 ps for LSO and 576 ps for LaBr 3, while not matching the best literature results using analog electronics, are already well below 1 ns and fully adequate for a wide variety of experiments. These results are shown not to be limited by the DPPs themselves, which achieved 57 ps time resolution using a pulser, but are degraded in part both by the somewhat limited number of photoelectrons we collected and by a sub-optimum choice of PMT. Analysis further suggests that increasing the sampling speed would further improve performance. We therefore conclude that DPP time-of-arrival resolution is already adequate to supplant analog processing in many applications and that further improvements could be achieved with only modest efforts.

  8. IS THE GALACTIC COSMIC-RAY SPECTRUM CONSTANT IN TIME?

    SciTech Connect

    Eichler, David; Kumar, Rahul; Pohl, Martin E-mail: rahuliitk@gmail.com

    2013-06-01

    The hypothesis is considered that the present, local Galactic cosmic-ray spectrum is, due to source intermittency, softer than average over time and over the Galaxy. Measurements of muogenic nuclides underground could provide an independent measurement of the time-averaged spectrum. Source intermittency could also account for the surprising low anisotropy reported by the IceCube Collaboration. Predictions for Galactic emission of ultrahigh-energy (UHE) quanta, such as UHE gamma rays and neutrinos, might be higher or lower than previously estimated.

  9. Constant pressure and temperature discrete-time Langevin molecular dynamics

    SciTech Connect

    Grønbech-Jensen, Niels; Farago, Oded

    2014-11-21

    We present a new and improved method for simultaneous control of temperature and pressure in molecular dynamics simulations with periodic boundary conditions. The thermostat-barostat equations are built on our previously developed stochastic thermostat, which has been shown to provide correct statistical configurational sampling for any time step that yields stable trajectories. Here, we extend the method and develop a set of discrete-time equations of motion for both particle dynamics and system volume in order to seek pressure control that is insensitive to the choice of the numerical time step. The resulting method is simple, practical, and efficient. The method is demonstrated through direct numerical simulations of two characteristic model systems—a one-dimensional particle chain for which exact statistical results can be obtained and used as benchmarks, and a three-dimensional system of Lennard-Jones interacting particles simulated in both solid and liquid phases. The results, which are compared against the method of Kolb and Dünweg [J. Chem. Phys. 111, 4453 (1999)], show that the new method behaves according to the objective, namely that acquired statistical averages and fluctuations of configurational measures are accurate and robust against the chosen time step applied to the simulation.

  10. Time and Space Resolved Heat Transfer Measurements Under Nucleate Bubbles with Constant Heat Flux Boundary Conditions

    NASA Technical Reports Server (NTRS)

    Myers, Jerry G.; Hussey, Sam W.; Yee, Glenda F.; Kim, Jungho

    2003-01-01

    Investigations into single bubble pool boiling phenomena are often complicated by the difficulties in obtaining time and space resolved information in the bubble region. This usually occurs because the heaters and diagnostics used to measure heat transfer data are often on the order of, or larger than, the bubble characteristic length or region of influence. This has contributed to the development of many different and sometimes contradictory models of pool boiling phenomena and dominant heat transfer mechanisms. Recent investigations by Yaddanapyddi and Kim and Demiray and Kim have obtained time and space resolved heat transfer information at the bubble/heater interface under constant temperature conditions using a novel micro-heater array (10x10 array, each heater 100 microns on a side) that is semi-transparent and doubles as a measurement sensor. By using active feedback to maintain a state of constant temperature at the heater surface, they showed that the area of influence of bubbles generated in FC-72 was much smaller than predicted by standard models and that micro-conduction/micro-convection due to re-wetting dominated heat transfer effects. This study seeks to expand on the previous work by making time and space resolved measurements under bubbles nucleating on a micro-heater array operated under constant heat flux conditions. In the planned investigation, wall temperature measurements made under a single bubble nucleation site will be synchronized with high-speed video to allow analysis of the bubble energy removal from the wall.

  11. Comparison of Constant Time Delay and the System of Least Prompts in Teaching Chained Tasks.

    ERIC Educational Resources Information Center

    Wolery, Mark; And Others

    1990-01-01

    Four students (ages 10-14) with moderate mental retardation learned chained tasks with constant time delay and with the system of least prompts. Both strategies produced criterion-level performance; however, constant time delay was more efficient than least prompts in terms of number of sessions, percent of errors, and direct instructional time to…

  12. 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. PMID:26931831

  13. Dynamics of Perceived Exertion in Constant-Power Cycling: Time- and Workload-Dependent Thresholds

    ERIC Educational Resources Information Center

    Balagué, Natàlia; Hristovski, Robert; García, Sergi; Aguirre, Cecilia; Vázquez, Pablo; Razon, Selen; Tenenbaum, Gershon

    2015-01-01

    Purpose: The purpose of this study was to test the dynamics of perceived exertion shifts (PES) as a function of time and workload during constant-power cycling. Method: Fifty-two participants assigned to 4 groups performed a cycling task at 4 different constant workloads corresponding to their individual rates of perceived exertion (RPEs = 13, 15,…

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

    PubMed Central

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

    2016-01-01

    Study Objectives: 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. Methods: 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. Results: 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). Conclusions: 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. Citation: Wiriyaporn D, Wang L, Aboussouan LS. Expiratory time constant and sleep apnea severity in the overlap syndrome. J Clin Sleep Med 2016;12(3):327–332. PMID:26414979

  15. Calculation of reaction rate constants using approximate evolution of quantum trajectories in imaginary and real time

    NASA Astrophysics Data System (ADS)

    Garashchuk, Sophya

    2010-05-01

    Reaction rate constants can be directly obtained from evolution of the flux operator eigenvectors under the Boltzmann and Hamiltonian operators. This is achieved by evolving the quantum trajectory ensemble, representing a wavefunction, in imaginary time seamlessly switching to the real-time dynamics. Quantum-mechanical effects are incorporated through the quantum potential dependent on the trajectory momenta or on the derivatives of the wavefunction amplitude. For practicality the quantum potential and wavefunction nodes are described using linear basis, which is exact for Gaussian wavefunctions. For the Eckart barrier approximate rate constants show significant improvement over the parabolic barrier rate constants.

  16. Time constants and feedback transfer functions of EBR-II (Experimental Breeder Reactor) subassembly types

    SciTech Connect

    Grimm, K.N.; Meneghetti, D.

    1986-09-01

    Time constants, feedback reactivity transfer functions and power coefficients are calculated for stereotypical subassemblies in the EBR-II reactor. These quantities are calculated from nodal reactivities obtained from a reactor kinetic code analysis for a step change in power. Due to the multiplicity of eigenvalues, there are several time constants for each nodal position in a subassembly. Compared with these calculated values are analytically derived values for the initial node of a given channel.

  17. Decreased time constant of the pulmonary circulation in chronic thromboembolic pulmonary hypertension.

    PubMed

    MacKenzie Ross, Robert V; Toshner, Mark R; Soon, Elaine; Naeije, Robert; Pepke-Zaba, Joanna

    2013-07-15

    This study analyzed the relationship between pulmonary vascular resistance (PVR) and pulmonary arterial compliance (Ca) in patients with idiopathic pulmonary arterial hypertension (IPAH) and proximal chronic thromboembolic pulmonary hypertension (CTEPH). It has recently been shown that the time constant of the pulmonary circulation (RC time constant), or PVR × Ca, remains unaltered in various forms and severities of pulmonary hypertension, with the exception of left heart failure. We reasoned that increased wave reflection in proximal CTEPH would be another cause of the decreased RC time constant. We conducted a retrospective analysis of invasive pulmonary hemodynamic measurements in IPAH (n = 78), proximal CTEPH (n = 91) before (pre) and after (post) pulmonary endarterectomy (PEA), and distal CTEPH (n = 53). Proximal CTEPH was defined by a postoperative mean pulmonary artery pressure (PAP) of ≤25 mmHg. Outcome measures were the RC time constant, PVR, Ca, and relationship between systolic and mean PAPs. The RC time constant for pre-PEA CTEPH was 0.49 ± 0.11 s compared with post-PEA-CTEPH (0.37 ± 0.11 s, P < 0.0001), IPAH (0.63 ± 0.14 s, P < 0.001), and distal CTEPH (0.55 ± 0.12 s, P < 0.05). A shorter RC time constant was associated with a disproportionate decrease in systolic PAP with respect to mean PAP. We concluded that the pulmonary RC time constant is decreased in proximal CTEPH compared with IPAH, pre- and post-PEA, which may be explained by increased wave reflection but also, importantly, by persistent structural changes after the removal of proximal obstructions. A reduced RC time constant in CTEPH is in accord with a wider pulse pressure and hence greater right ventricular work for a given mean PAP.

  18. Computation of Rate Constants for Diffusion of Small Ligands to and from Buried Protein Active Sites.

    PubMed

    Wang, P-H; De Sancho, D; Best, R B; Blumberger, J

    2016-01-01

    The diffusion of ligands to actives sites of proteins is essential to enzyme catalysis and many cellular signaling processes. In this contribution we review our recently developed methodology for calculation of rate constants for diffusion and binding of small molecules to buried protein active sites. The diffusive dynamics of the ligand obtained from molecular dynamics simulation is coarse grained and described by a Markov state model. Diffusion and binding rate constants are then obtained either from the reactive flux formalism or by fitting the time-dependent population of the Markov state model to a phenomenological rate law. The method is illustrated by applications to diffusion of substrate and inhibitors in [NiFe] hydrogenase, CO-dehydrogenase, and myoglobin. We also discuss a recently developed sensitivity analysis that allows one to identify hot spots in proteins, where mutations are expected to have the strongest effects on ligand diffusion rates.

  19. Computation of Rate Constants for Diffusion of Small Ligands to and from Buried Protein Active Sites.

    PubMed

    Wang, P-H; De Sancho, D; Best, R B; Blumberger, J

    2016-01-01

    The diffusion of ligands to actives sites of proteins is essential to enzyme catalysis and many cellular signaling processes. In this contribution we review our recently developed methodology for calculation of rate constants for diffusion and binding of small molecules to buried protein active sites. The diffusive dynamics of the ligand obtained from molecular dynamics simulation is coarse grained and described by a Markov state model. Diffusion and binding rate constants are then obtained either from the reactive flux formalism or by fitting the time-dependent population of the Markov state model to a phenomenological rate law. The method is illustrated by applications to diffusion of substrate and inhibitors in [NiFe] hydrogenase, CO-dehydrogenase, and myoglobin. We also discuss a recently developed sensitivity analysis that allows one to identify hot spots in proteins, where mutations are expected to have the strongest effects on ligand diffusion rates. PMID:27497172

  20. Theory of diffusion of active particles that move at constant speed in two dimensions

    NASA Astrophysics Data System (ADS)

    Sevilla, Francisco J.; Gómez Nava, Luis A.

    2014-08-01

    Starting from a Langevin description of active particles that move with constant speed in infinite two-dimensional space and its corresponding Fokker-Planck equation, we develop a systematic method that allows us to obtain the coarse-grained probability density of finding a particle at a given location and at a given time in arbitrary short-time regimes. By going beyond the diffusive limit, we derive a generalization of the telegrapher equation. Such generalization preserves the hyperbolic structure of the equation and incorporates memory effects in the diffusive term. While no difference is observed for the mean-square displacement computed from the two-dimensional telegrapher equation and from our generalization, the kurtosis results in a sensible parameter that discriminates between both approximations. We carry out a comparative analysis in Fourier space that sheds light on why the standard telegrapher equation is not an appropriate model to describe the propagation of particles with constant speed in dispersive media.

  1. Influence of the loss of time-constants repertoire in pathologic heartbeat dynamics

    NASA Astrophysics Data System (ADS)

    Guzmán-Vargas, L.; Muñoz-Diosdado, A.; Angulo-Brown, F.

    2005-03-01

    We present a fractal analysis of diurnal heart interbeat time series from healthy young subjects and patients with congestive heart failure. We describe some differences between these groups by means of the calculation of some scale-invariant exponents. A previous simple model to reproduce the observed differences is briefly described (Phys. Rev. E 67 (2003) 052901). The model is based in first-order autoregressive processes and consists in the combination of time constants. We suggest that some changes occurring with disease could be related to the participation or absence of time constants. Finally, we also present a multifractal analysis of simulated sequences and their comparison with real data.

  2. Primary reactions in photosynthetic reaction centers of Rhodobacter sphaeroides - Time constants of the initial electron transfer

    NASA Astrophysics Data System (ADS)

    Dominguez, Pablo Nahuel; Himmelstoss, Matthias; Michelmann, Jeff; Lehner, Florian Thomas; Gardiner, Alastair T.; Cogdell, Richard J.; Zinth, Wolfgang

    2014-05-01

    The primary dynamics of reaction centers from Rhodobacter sphaeroides at room temperature are studied at low excitation intensities and low excitation rates. Analysis based on singular value decomposition yields three time constants in the picosecond range (ca. 1.2 ps, 3.5 ps and 220 ps). The spectral and temporal signatures are fully consistent with the step-wise electron transfer model published previously, with a first electron transfer to the bacteriochlorophyll with a time constant of 3.5 ps and a second 1.2 ps transfer to the bacteriopheophytin. No indications for adiabatic electron transfer are found in the time range >0.5 ps.

  3. Measurements of the time constant for steady ionization in shaped-charge barium releases

    NASA Technical Reports Server (NTRS)

    Hoch, Edward L.; Hallinan, Thomas J.

    1993-01-01

    Quantitative measurements of three solar illuminated shaped-charge barium releases injected at small angles to the magnetic field were made using a calibrated color television camera. Two of the releases were from 1989. The third release, a reanalysis of an event included in Hallinan's 1988 study of three 1986 releases, was included to provide continuity between the two studies. Time constants for ionization, measured during the first 25 s of each release, were found to vary considerably. The two 1989 time constants differed substantially, and both were significantly less than any of the 1986 time constants. On the basis of this variability, we conclude that the two 1989 releases showed evidence of continuous nonsolar ionization. One release showed nonsolar ionization which could not he attributed to Alfven's critical ionization velocity process, which requires a component of velocity perpendicular to the magnetic field providing a perpendicular energy greater than the ionization potential.

  4. Competing bounds on the present-day time variation of fundamental constants

    SciTech Connect

    Dent, Thomas; Stern, Steffen; Wetterich, Christof

    2009-04-15

    We compare the sensitivity of a recent bound on time variation of the fine structure constant from optical clocks with bounds on time-varying fundamental constants from atomic clocks sensitive to the electron-to-proton mass ratio, from radioactive decay rates in meteorites, and from the Oklo natural reactor. Tests of the weak equivalence principle also lead to comparable bounds on present variations of constants. The 'winner in sensitivity' depends on what relations exist between the variations of different couplings in the standard model of particle physics, which may arise from the unification of gauge interactions. Weak equivalence principle tests are currently the most sensitive within unified scenarios. A detection of time variation in atomic clocks would favor dynamical dark energy and put strong constraints on the dynamics of a cosmological scalar field.

  5. Competing bounds on the present-day time variation of fundamental constants

    NASA Astrophysics Data System (ADS)

    Dent, Thomas; Stern, Steffen; Wetterich, Christof

    2009-04-01

    We compare the sensitivity of a recent bound on time variation of the fine structure constant from optical clocks with bounds on time-varying fundamental constants from atomic clocks sensitive to the electron-to-proton mass ratio, from radioactive decay rates in meteorites, and from the Oklo natural reactor. Tests of the weak equivalence principle also lead to comparable bounds on present variations of constants. The “winner in sensitivity” depends on what relations exist between the variations of different couplings in the standard model of particle physics, which may arise from the unification of gauge interactions. Weak equivalence principle tests are currently the most sensitive within unified scenarios. A detection of time variation in atomic clocks would favor dynamical dark energy and put strong constraints on the dynamics of a cosmological scalar field.

  6. A Comparison of Simultaneous Prompting and Constant Time Delay Procedures in Teaching State Capitals

    ERIC Educational Resources Information Center

    Head, Kenneth David; Collins, Belva C.; Schuster, John W.; Ault, Melinda Jones

    2011-01-01

    This investigation compared the effectiveness and efficiency of constant time delay (CTD) and simultaneous prompting (SP) procedures in teaching discrete social studies facts to 4 high school students with learning and behavior disorders using an adapted alternating treatments design nested within a multiple probe design. The results indicated…

  7. A Comparison of Flexible Prompt Fading and Constant Time Delay for Five Children with Autism

    ERIC Educational Resources Information Center

    Soluaga, Doris; Leaf, Justin B.; Taubman, Mitchell; McEachin, John; Leaf, Ron

    2008-01-01

    Given the increasing rates of autism, identifying prompting procedures that can assist in the development of more optimal learning opportunities for this population is critical. Extensive empirical research exists supporting the effectiveness of various prompting strategies. Constant time delay (CTD) is a highly implemented prompting procedure…

  8. Using a Constant Time Delay Procedure to Teach Foundational Swimming Skills to Children with Autism

    ERIC Educational Resources Information Center

    Rogers, Laura; Hemmeter, Mary Louise; Wolery, Mark

    2010-01-01

    The purpose of this study was to evaluate the effectiveness of using a constant time delay procedure to teach foundational swimming skills to three children with autism. The skills included flutter kick, front-crawl arm strokes, and head turns to the side. A multiple-probe design across behaviors and replicated across participants was used.…

  9. Time constant measurement for control of induction heating processes for thixoforming

    NASA Astrophysics Data System (ADS)

    Gerlach, O.; Lechler, A.; Verl, A.

    2015-02-01

    In controlling induction heating systems, several measurement methods exist for controlled heating of metal billets into the semi-solid state for thixoforming. The most common approach is to measure the billet temperature, which suffers from various drawbacks leading to difficulties in process stability. The main disadvantages are the small temperature range of the process window and the alloy composition dependency of the correlation between temperature and liquid fraction. An alternative is to determine the liquid fraction of the billet by measuring the time constant of the load. Although time constant measurement is not affected by the mentioned problems, it is difficult to use it as a controlled variable. This paper shows that disturbances affecting time constant measurement are mainly caused by semiconductor losses inside the inverter. A method is introduced to compensate these losses. This method was implemented and tested in the embedded system of an induction heating unit, thereby showing that it is possible to use time constant measurement to determine the liquid fraction of a billet during induction heating.

  10. Concept for sleeve induction motor with 1-msec mechanical time constant

    NASA Technical Reports Server (NTRS)

    Wiegand, D. E.

    1968-01-01

    Conductive sleeve induction motor having a 1-msec mechanical time constant is used with solid-state devices to control all-electric servo power systems. The servomotor rotor inertia is small compared to the maximum force rating of the servo motion, permitting high no-load acceleration.

  11. Transport reversals of chiral active particles induced by a perpendicular constant force

    NASA Astrophysics Data System (ADS)

    Wu, Jian-chun; Zhou, Jia-ning; Ai, Bao-quan

    2016-11-01

    Transport of chiral active particles in a symmetric periodic potential is investigated in the presence of a constant force. It is found that due to chirality of active particles the transversal constant force can break the symmetry of the system and induce a longitudinal net current. There exists an optimal constant force at which the rectification is maximal. Remarkably, longitudinal current reversals can occur by suitably tailoring the transversal constant force. Therefore, particles with different chiralities move to different directions and can be effectively separated.

  12. Delay decomposition at a single server queue with constant service time and multiple inputs

    NASA Technical Reports Server (NTRS)

    Ziegler, C.; Schilling, D. L.

    1978-01-01

    Two network consisting of single server queues, each with a constant service time, are considered. The external inputs to each network are assumed to follow some general probability distribution. Several interesting equivalencies that exist between the two networks considered are derived. This leads to the introduction of an important concept in delay decomposition. It is shown that the waiting time experienced by a customer can be decomposed into two basic components called self-delay and interference delay.

  13. 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.

  14. In vivo Target Residence Time and Kinetic Selectivity: The Association Rate Constant as Determinant.

    PubMed

    de Witte, Wilhelmus E A; Danhof, Meindert; van der Graaf, Piet H; de Lange, Elizabeth C M

    2016-10-01

    It is generally accepted that, in conjunction with pharmacokinetics, the first-order rate constant of target dissociation is a major determinant of the time course and duration of in vivo target occupancy. Here we show that the second-order rate constant of target association can be equally important. On the basis of the commonly used mathematical models for drug-target binding, it is shown that a high target association rate constant can increase the (local) concentration of the drug, which decreases the rate of decline of target occupancy. The increased drug concentration can also lead to increased off-target binding and decreased selectivity. Therefore, the kinetics of both target association and dissociation need to be taken into account in the selection of drug candidates with optimal pharmacodynamic properties.

  15. In vivo Target Residence Time and Kinetic Selectivity: The Association Rate Constant as Determinant.

    PubMed

    de Witte, Wilhelmus E A; Danhof, Meindert; van der Graaf, Piet H; de Lange, Elizabeth C M

    2016-10-01

    It is generally accepted that, in conjunction with pharmacokinetics, the first-order rate constant of target dissociation is a major determinant of the time course and duration of in vivo target occupancy. Here we show that the second-order rate constant of target association can be equally important. On the basis of the commonly used mathematical models for drug-target binding, it is shown that a high target association rate constant can increase the (local) concentration of the drug, which decreases the rate of decline of target occupancy. The increased drug concentration can also lead to increased off-target binding and decreased selectivity. Therefore, the kinetics of both target association and dissociation need to be taken into account in the selection of drug candidates with optimal pharmacodynamic properties. PMID:27394919

  16. Response of body size and developmental time of Tribolium castaneum to constant versus fluctuating thermal conditions.

    PubMed

    Małek, D; Drobniak, S; Gozdek, A; Pawlik, K; Kramarz, P

    2015-07-01

    Temperature has profound effects on biological functions at all levels of organization. In ectotherms, body size is usually negatively correlated with ambient temperature during development, a phenomenon known as The Temperature-Size Rule (TSR). However, a growing number of studies have indicated that temperature fluctuations have a large influence on life history traits and the implications of such fluctuations for the TSR are unknown. Our study investigated the effect of different constant and fluctuating temperatures on the body mass and development time of red flour beetles (Tribolium castaneum Herbst, 1797); we also examined whether the sexes differed in their responses to thermal conditions. We exposed the progeny of half-sib families of a T. castaneum laboratory strain to one of four temperature regimes: constant 30°C, constant 25°C, fluctuating with a daily mean of 30°C, or fluctuating with a daily mean of 25°C. Sex-specific development time and body mass at emergence were determined. Beetles developed the fastest and had the greatest body mass upon emergence when they were exposed to a constant temperature of 30°C. This pattern was reversed when beetles experienced a constant temperature of 25°C: slowest development and lowest body mass upon emergence were observed. Fluctuations changed those effects significantly - impact of temperature on development time was smaller, while differences in body mass disappeared completely. Our results do not fit TSR predictions. Furthermore, regardless of the temperature regime, females acquired more mass, while there were no differences between sexes in development time to eclosion. This finding fails to support one of the explanations for smaller male size: that selection favors the early emergence of males. We found no evidence of genotype × environment interactions for selected set of traits.

  17. Memory efficient and constant time 2D-recursive spatial averaging filter for embedded implementations

    NASA Astrophysics Data System (ADS)

    Gan, Qifeng; Seoud, Lama; Ben Tahar, Houssem; Langlois, J. M. Pierre

    2016-04-01

    Spatial Averaging Filters (SAF) are extensively used in image processing for image smoothing and denoising. Their latest implementations have already achieved constant time computational complexity regardless of kernel size. However, all the existing O(1) algorithms require additional memory for temporary data storage. In order to minimize memory usage in embedded systems, we introduce a new two-dimensional recursive SAF. It uses previous resultant pixel values along both rows and columns to calculate the current one. It can achieve constant time computational complexity without using any additional memory usage. Experimental comparisons with previous SAF implementations shows that the proposed 2D-Recursive SAF does not require any additional memory while offering a computational time similar to the most efficient existing SAF algorithm. These features make it especially suitable for embedded systems with limited memory capacity.

  18. How Strongly does Dating Meteorites Constrain the Time-Dependence of the Fine-Structure Constant?

    NASA Astrophysics Data System (ADS)

    Fujii, Yasunori; Iwamoto, Akira

    We review our argument on the nature of the so-called meteorite constraint on the possible time-dependence of the fine-structure constant, emphasizing that dating meteorites at the present time is different in principle from searching directly for the traces in the past, as in the Oklo phenomenon and the QSO absorption lines. In the related literature, we still find some arguments not necessarily consistent with this difference to be taken properly into account. It does not immediately follow that any model-dependent approaches are useless in practice, though we cannot help suspecting that dating meteorites is no match for the Oklo and the QSO in probing the time-variability of the fine-structure constant, at this moment. Some of the relevance to the QSO data particularly in terms of the scalar field will be discussed.

  19. Bipolar square-wave current source for transient electromagnetic systems based on constant shutdown time

    NASA Astrophysics Data System (ADS)

    Wang, Shilong; Yin, Changchun; Lin, Jun; Yang, Yu; Hu, Xueyan

    2016-03-01

    Cooperative work of multiple magnetic transmitting sources is a new trend in the development of transient electromagnetic system. The key is the bipolar current waves shutdown, concurrently in the inductive load. In the past, it was difficult to use the constant clamping voltage technique to realize the synchronized shutdown of currents with different peak values. Based on clamping voltage technique, we introduce a new controlling method with constant shutdown time. We use the rising time to control shutdown time and use low voltage power source to control peak current. From the viewpoint of the circuit energy loss, by taking the high-voltage capacitor bypass resistance and the capacitor of the passive snubber circuit into account, we establish the relationship between the rising time and the shutdown time. Since the switch is not ideal, we propose a new method to test the shutdown time by the low voltage, the high voltage and the peak current. Experimental results show that adjustment of the current rising time can precisely control the value of the clamp voltage. When the rising time is fixed, the shutdown time is unchanged. The error for shutdown time deduced from the energy consumption is less than 6%. The new controlling method on current shutdown proposed in this paper can be used in the cooperative work of borehole and ground transmitting system.

  20. Real-time method and apparatus for measuring the decay-time constant of a fluorescing phosphor

    DOEpatents

    Britton, Jr., Charles L.; Beshears, David L.; Simpson, Marc L.; Cates, Michael R.; Allison, Steve W.

    1999-01-01

    A method for determining the decay-time constant of a fluorescing phosphor is provided, together with an apparatus for performing the method. The apparatus includes a photodetector for detecting light emitted by a phosphor irradiated with an excitation pulse and for converting the detected light into an electrical signal. The apparatus further includes a differentiator for differentiating the electrical signal and a zero-crossing discrimination circuit that outputs a pulse signal having a pulse width corresponding to the time period between the start of the excitation pulse and the time when the differentiated electrical signal reaches zero. The width of the output pulse signal is proportional to the decay-time constant of the phosphor.

  1. Delay decomposition at a single server queue with constant service time and multiple inputs. [Waiting time on computer network

    NASA Technical Reports Server (NTRS)

    Ziegler, C.; Schilling, D. L.

    1977-01-01

    Two networks consisting of single server queues, each with a constant service time, are considered. The external inputs to each network are assumed to follow some general probability distribution. Several interesting equivalencies that exist between the two networks considered are derived. This leads to the introduction of an important concept in delay decomposition. It is shown that the waiting time experienced by a customer can be decomposed into two basic components called self delay and interference delay.

  2. The method of variation of constants and multiple time scales in orbital mechanics.

    PubMed

    Newman, William I; Efroimsky, Michael

    2003-06-01

    The method of variation of constants is an important tool used to solve systems of ordinary differential equations, and was invented by Euler and Lagrange to solve a problem in orbital mechanics. This methodology assumes that certain "constants" associated with a homogeneous problem will vary in time in response to an external force. It also introduces one or more constraint equations. We show that these constraints can be generalized in analogy to gauge theories in physics, and that different constraints can offer conceptual advances and methodological benefits to the solution of the underlying problem. Examples are given from linear ordinary differential equation theory and from orbital mechanics. However, a slow driving force in the presence of multiple time scales contained in the underlying (homogeneous) problem nevertheless requires special care, and this has strong implications to the analytic and numerical solutions of problems ranging from celestial mechanics to molecular dynamics. (c) 2003 American Institute of Physics. PMID:12777110

  3. The method of variation of constants and multiple time scales in orbital mechanics.

    PubMed

    Newman, William I; Efroimsky, Michael

    2003-06-01

    The method of variation of constants is an important tool used to solve systems of ordinary differential equations, and was invented by Euler and Lagrange to solve a problem in orbital mechanics. This methodology assumes that certain "constants" associated with a homogeneous problem will vary in time in response to an external force. It also introduces one or more constraint equations. We show that these constraints can be generalized in analogy to gauge theories in physics, and that different constraints can offer conceptual advances and methodological benefits to the solution of the underlying problem. Examples are given from linear ordinary differential equation theory and from orbital mechanics. However, a slow driving force in the presence of multiple time scales contained in the underlying (homogeneous) problem nevertheless requires special care, and this has strong implications to the analytic and numerical solutions of problems ranging from celestial mechanics to molecular dynamics. (c) 2003 American Institute of Physics.

  4. Constant-net-time headway as a key mechanism behind pedestrian flow dynamics.

    PubMed

    Johansson, Anders

    2009-08-01

    We show that keeping a constant lower limit on the net-time headway is the key mechanism behind the dynamics of pedestrian streams. There is a large variety in flow and speed as functions of density for empirical data of pedestrian streams obtained from studies in different countries. The net-time headway, however, stays approximately constant over all these different data sets. By using this fact, we demonstrate how the underlying dynamics of pedestrian crowds, naturally follows from local interactions. This means that there is no need to come up with an arbitrary fit function (with arbitrary fit parameters) as has traditionally been done. Further, by using not only the average density values but the variance as well, we show how the recently reported stop-and-go waves [Helbing, Phys. Rev. E 75, 046109 (2007)] emerge when local density variations take values exceeding a certain maximum global (average) density, which makes pedestrians stop.

  5. Simulating diffusion processes in discontinuous media: A numerical scheme with constant time steps

    SciTech Connect

    Lejay, Antoine; Pichot, Geraldine

    2012-08-30

    In this article, we propose new Monte Carlo techniques for moving a diffusive particle in a discontinuous media. In this framework, we characterize the stochastic process that governs the positions of the particle. The key tool is the reduction of the process to a Skew Brownian motion (SBM). In a zone where the coefficients are locally constant on each side of the discontinuity, the new position of the particle after a constant time step is sampled from the exact distribution of the SBM process at the considered time. To do so, we propose two different but equivalent algorithms: a two-steps simulation with a stop at the discontinuity and a one-step direct simulation of the SBM dynamic. Some benchmark tests illustrate their effectiveness.

  6. Re/Os Constraint on the Time Variability of the Fine-Structure Constant

    NASA Astrophysics Data System (ADS)

    Fujii, Yasunori; Iwamoto, Akira

    2003-12-01

    We argue that the accuracy by which the isochron parameters of the decay 187Re→187Os are determined by dating iron meteorites may constrain the possible time dependence of the decay rate and hence of the fine-structure constant α, not directly but only in a model-dependent manner. From this point of view, some of the attempts to analyze the Oklo constraint and the results of the quasistellar-object absorption lines are reexamined.

  7. Re/Os constraint on the time variability of the fine-structure constant.

    PubMed

    Fujii, Yasunori; Iwamoto, Akira

    2003-12-31

    We argue that the accuracy by which the isochron parameters of the decay 187Re-->187Os are determined by dating iron meteorites may constrain the possible time dependence of the decay rate and hence of the fine-structure constant alpha, not directly but only in a model-dependent manner. From this point of view, some of the attempts to analyze the Oklo constraint and the results of the quasistellar-object absorption lines are reexamined.

  8. Isothermal Titration Calorimetry in Nanoliter Droplets with Sub-Second Time Constants

    PubMed Central

    Lubbers, Brad; Baudenbacher, Franz

    2011-01-01

    We reduced the reaction volume in microfabricated suspended-membrane titration calorimeters to nanoliter droplets and improved the sensitivities to below a nanowatt with time constants of around 100ms, The device performance was characterized using exothermic acid-base neutralizations and a detailed numerical model. The finite element based numerical model allowed us to determine the sensitivities within 1% and the temporal dynamics of the temperature rise in neutralization reactions as a function of droplet size. The model was used to determine the optimum calorimeter design (membrane size and thickness, junction area, and thermopile thickness) and sensitivities for sample volumes of 1 nl for silicon nitride and polymer membranes. We obtained a maximum sensitivity of 153 pW/√Hz for a 1 μm SiN membrane and 79 pW/√Hz for a 1 μm polymer membrane. The time constant of the calorimeter system was determined experimentally by using a pulsed laser to increase the temperature of nanoliter sample volumes. For a 2.5 nanoliter sample volume, we experimentally determined a noise equivalent power of 500 pW/√Hz and a 1/e time constant of 110ms for a modified commercially available infrared sensor with a thin-film thermopile. Furthermore, we demonstrated detection of 1.4 nJ reaction energies from injection of 25 pl of 1 mM HCl into a 2.5 nl droplet of 1 mM NaOH. PMID:21913688

  9. Thermal time constant: optimising the skin temperature predictive modelling in lower limb prostheses using Gaussian processes

    PubMed Central

    Buis, Arjan

    2016-01-01

    Elevated skin temperature at the body/device interface of lower-limb prostheses is one of the major factors that affect tissue health. The heat dissipation in prosthetic sockets is greatly influenced by the thermal conductive properties of the hard socket and liner material employed. However, monitoring of the interface temperature at skin level in lower-limb prosthesis is notoriously complicated. This is due to the flexible nature of the interface liners used which requires consistent positioning of sensors during donning and doffing. Predicting the residual limb temperature by monitoring the temperature between socket and liner rather than skin and liner could be an important step in alleviating complaints on increased temperature and perspiration in prosthetic sockets. To predict the residual limb temperature, a machine learning algorithm – Gaussian processes is employed, which utilizes the thermal time constant values of commonly used socket and liner materials. This Letter highlights the relevance of thermal time constant of prosthetic materials in Gaussian processes technique which would be useful in addressing the challenge of non-invasively monitoring the residual limb skin temperature. With the introduction of thermal time constant, the model can be optimised and generalised for a given prosthetic setup, thereby making the predictions more reliable. PMID:27695626

  10. Time Variation of the Fine Structure Constant in the Spacetime of a Cosmic Domain Wall

    NASA Astrophysics Data System (ADS)

    Campanelli, L.; Cea, P.; Tedesco, L.

    The gravitational field produced by a domain wall acts as a medium with spacetime-dependent permittivity ɛ. Therefore, the fine structure constant α=e2/4πɛ will be a time-dependent function at fixed position. The most stringent constraint on the time-variation of α comes from the natural reactor Oklo and gives |˙ α /α | < few × 10-17 yr-1. This limit constrains the tension of a cosmic domain wall to be less than σ ≲ 10-2 MeV3, and then represents the most severe limit on the energy density of a cosmic wall stretching our Universe.

  11. HUBBLE CONSTANT, LENSING, AND TIME DELAY IN RELATIVISTIC MODIFIED NEWTONIAN DYNAMICS

    SciTech Connect

    Tian, Yong; Ko, Chung-Ming; Chiu, Mu-Chen E-mail: cmko@astro.ncu.edu.tw

    2013-06-20

    The time delay in galaxy gravitational lensing systems has been used to determine the value of the Hubble constant. As with other dynamical phenomena on the galaxy scale, dark matter is often invoked in gravitational lensing to account for the 'missing mass' (the apparent discrepancy between the dynamical mass and the luminous mass). Alternatively, modified gravity can be used to explain the discrepancy. In this paper, we adopt the tensor-vector-scalar gravity (TeVe S), a relativistic version of Modified Newtonian Dynamics, to study gravitational lensing phenomena and derive the formulae needed to evaluate the Hubble constant. We test our method on quasar lensing by elliptical galaxies in the literature. We focus on double-image systems with time delay measurement. Three candidates are suitable for our study: HE 2149-2745, FBQ J0951+2635, and SBS 0909+532. The Hubble constant obtained is consistent with the value used to fit the cosmic microwave background result in a neutrino cosmological model.

  12. Measuring JHH values with a selective constant-time 2D NMR protocol

    NASA Astrophysics Data System (ADS)

    Lin, Liangjie; Wei, Zhiliang; Lin, Yanqin; Chen, Zhong

    2016-11-01

    Proton-proton scalar couplings play important roles in molecule structure elucidation. However, measurements of JHH values in complex coupled spin systems remain challenging. In this study, we develop a selective constant-time (SECT) 2D NMR protocol with which scalar coupling networks involving chosen protons can be revealed, and corresponding JHH values can be measured through doublets along the F1 dimension. All JHH values within a network of n fully coupled protons can be separately determined with (n - 1) SECT experiments. Additionally, the proposed pulse sequence possesses satisfactory sensitivity and handy implementation. Therefore, it will interest scientists who intend to address structural analyzes of molecules with overcrowded spectra, and may greatly facilitate the applications of scalar-coupling constants in molecule structure studies.

  13. Assessment of the time constant of relaxation: insights from simulations and hemodynamic measurements

    NASA Technical Reports Server (NTRS)

    De Mey, S.; Thomas, J. D.; Greenberg, N. L.; Vandervoort, P. M.; Verdonck, P. R.

    2001-01-01

    The objective of this study was to use high-fidelity animal data and numerical simulations to gain more insight into the reliability of the estimated relaxation constant derived from left ventricular pressure decays, assuming a monoexponential model with either a fixed zero or free moving pressure asymptote. Comparison of the experimental data with the results of the simulations demonstrated a trade off between the fixed zero and the free moving asymptote approach. The latter method more closely fits the pressure curves and has the advantage of producing an extra coefficient with potential diagnostic information. On the other hand, this method suffers from larger standard errors on the estimated coefficients. The method with fixed zero asymptote produces values of the time constant of isovolumetric relaxation (tau) within a narrow confidence interval. However, if the pressure curve is actually decaying to a nonzero pressure asymptote, this method results in an inferior fit of the pressure curve and a biased estimation of tau.

  14. Direct observation of single stationary-phase bacteria reveals a surprisingly long period of constant protein production activity

    PubMed Central

    Gefen, Orit; Fridman, Ofer; Ronin, Irine; Balaban, Nathalie Q.

    2014-01-01

    Exponentially growing bacteria are rarely found in the wild, as microorganisms tend to spend most of their lifetime at stationary phase. Despite this general prevalence of stationary-phase bacteria, they are as yet poorly characterized. Our goal was to quantitatively study this phase by direct observation of single bacteria as they enter into stationary phase and by monitoring their activity over several days during growth arrest. For this purpose, we devised an experimental procedure for starving single Escherichia coli bacteria in microfluidic devices and measured their activity by monitoring the production rate of fluorescent proteins. When amino acids were the sole carbon source, the production rate decreased by an order of magnitude upon entry into stationary phase. We found that, even while growth-arrested, bacteria continued to produce proteins at a surprisingly constant rate over several days. Our identification of this newly observed period of constant activity in nongrowing cells, designated as constant activity stationary phase, makes possible the conduction of assays that require constant protein expression over time, and are therefore difficult to perform under exponential growth conditions. Moreover, we show that exogenous protein expression bears no fitness cost on the regrowth of the population when starvation ends. Further characterization of constant activity stationary phase—a phase where nongrowing bacteria can be quantitatively studied over several days in a reproducible manner—should contribute to a better understanding of this ubiquitous but overlooked physiological state of bacteria in nature. PMID:24344288

  15. Electric field observations of time constants related to charging and charge neutralization processes in the ionosphere

    NASA Technical Reports Server (NTRS)

    Maynard, N. C.; Evans, D. S.; Troim, J.

    1982-01-01

    The Polar 5 electric field results are reviewed, and the transients from Polar 3 are presented. The phenomena are discussed from the standpoint of space charge. On the basis of the Polar 5 results, the large magnitude of the electric field from Polar 3 is seen as indicating that the observed space charge was probably within a few km or less of the payload. Reference is made to Cole's prediction (1960) that charges in the ionosphere would reach equilibrium with a time constant of the order of a few microsec. The processes involved in the two cases presented here require time constants of the order of ms. If the sheath dimensions are taken to be between 50 and 100 m, which is not considered unreasonable in view of the electric field measurements, then a qualitative estimate of the neutralization time would be the transit time for ions across the sheath. Since the kinetic velocity of a 1-eV proton is approximately 14 m/s, it would traverse the distance in 4 to 8 ms, assuming freedom of movement across magnetic field lines. This is the order of the decay times observed on Polar 5.

  16. Short time Fourier analysis of the electromyogram - Fast movements and constant contraction

    NASA Technical Reports Server (NTRS)

    Hannaford, Blake; Lehman, Steven

    1986-01-01

    Short-time Fourier analysis was applied to surface electromyograms (EMG) recorded during rapid movements, and during isometric contractions at constant forces. A portion of the data to be transformed by multiplying the signal by a Hamming window was selected, and then the discrete Fourier transform was computed. Shifting the window along the data record, a new spectrum was computed each 10 ms. The transformed data were displayed in spectograms or 'voiceprints'. This short-time technique made it possible to see time-dependencies in the EMG that are normally averaged in the Fourier analysis of these signals. Spectra of EMGs during isometric contractions at constant force vary in the short (10-20 ms) term. Short-time spectra from EMGs recorded during rapid movements were much less variable. The windowing technique picked out the typical 'three-burst pattern' in EMG's from both wrist and head movements. Spectra during the bursts were more consistent than those during isometric contractions. Furthermore, there was a consistent shift in spectral statistics in the course of the three bursts. Both the center frequency and the variance of the spectral energy distribution grew from the first burst to the second burst in the same muscle. The analogy between EMGs and speech signals is extended to argue for future applicability of short-time spectral analysis of EMG.

  17. Comparison of Constant Time Delay and the System of Least Prompts in Teaching Preschoolers with Developmental Delays.

    ERIC Educational Resources Information Center

    Doyle, Patricia; And Others

    1990-01-01

    The study compared the effectiveness and efficiency of constant time delay and the system of least prompts in teaching sight words to three developmentally delayed preschoolers. Results indicated that the constant time delay procedure resulted in fewer total trials, errors, percent of errors, and minutes of direct instructional time. (Author/DB)

  18. Strategies for obtaining long constant-pressure test times in shock tubes

    NASA Astrophysics Data System (ADS)

    Campbell, M. F.; Parise, T.; Tulgestke, A. M.; Spearrin, R. M.; Davidson, D. F.; Hanson, R. K.

    2015-11-01

    Several techniques have been developed for obtaining long, constant-pressure test times in reflected shock wave experiments in a shock tube, including the use of driver inserts, driver gas tailoring, helium gas diaphragm interfaces, driver extensions, and staged driver gas filling. These techniques are detailed here, including discussion on the most recent strategy, staged driver gas filling. Experiments indicate that this staged filling strategy increases available test time by roughly 20 % relative to single-stage filling of tailored driver gas mixtures, while simultaneously reducing the helium required per shock by up to 85 %. This filling scheme involves firstly mixing a tailored helium-nitrogen mixture in the driver section as in conventional driver filling and, secondly, backfilling a low-speed-of-sound gas such as nitrogen or carbon dioxide from a port close to the end cap of the driver section. Using this staged driver gas filling, in addition to the other techniques listed above, post-reflected shock test times of up to 0.102 s (102 ms) at 524 K and 1.6 atm have been obtained. Spectroscopically based temperature measurements in non-reactive mixtures have confirmed that temperature and pressure conditions remain constant throughout the length of these long test duration trials. Finally, these strategies have been used to measure low-temperature n-heptane ignition delay times.

  19. Time variation of the fine structure constant α from realistic models of Oklo reactors.

    NASA Astrophysics Data System (ADS)

    Gould, C. R.; Sharapov, E. I.; Lamoreaux, S. K.

    2006-11-01

    The topic of whether the fundamental constants of nature vary with time has been a subject of great interest since Dirac originally proposed the possibility that GN˜1/tuniverse. Recent observations of absorption spectra lines from distant quasars appeared to indicate a possible increase in the fine structure constant α over ten billion years. Contrarily, analyses of the time evolution of α from Oklo natural nuclear reactor data have yielded inconsistent results, some indicating a decrease over two billion years while others indicated no change. We have used known Oklo reactor epithermal spectral indices as criteria for selecting realistic reactor models. Reactors RZ2 and RZ10 were modeled with MCNP and the resulting neutron spectra were used to calculate the change in the ^149Sm capture cross section as a function of a possible shift in the energy of the 97.3-meV resonance. Our study resolves the contradictory situation with previous Oklo α-results. Our suggested 2 σ bound on a possible time variation of α over two billion years is stringent: -0.11 <=δαα <=0.24, in units of 10-7, but model dependent in that it assumes only α has varied over time.

  20. Antibody Constant Region Peptides Can Display Immunomodulatory Activity through Activation of the Dectin-1 Signalling Pathway

    PubMed Central

    Cenci, Elio; Monari, Claudia; Magliani, Walter; Ciociola, Tecla; Conti, Stefania; Gatti, Rita; Bistoni, Francesco; Polonelli, Luciano; Vecchiarelli, Anna

    2012-01-01

    We previously reported that a synthetic peptide with sequence identical to a CDR of a mouse monoclonal antibody specific for difucosyl human blood group A exerted an immunomodulatory activity on murine macrophages. It was therapeutic against systemic candidiasis without possessing direct candidacidal properties. Here we demonstrate that a selected peptide, N10K, putatively deriving from the enzymatic cleavage of the constant region (Fc) of human IgG1, is able to induce IL-6 secretion and pIkB-α activation. More importantly, it causes an up-regulation of Dectin-1 expression. This leads to an increased activation of β-glucan-induced pSyk, CARD9 and pIkB-α, and an increase in the production of pro-inflammatory cytokines such as IL-6, IL-12, IL-1β and TNF-α. The increased activation of this pathway coincides with an augmented phagocytosis of non opsonized Candida albicans cells by monocytes. The findings suggest that some Fc-peptides, potentially deriving from the proteolysis of immunoglobulins, may cause an unexpected immunoregulation in a way reminiscent of innate immunity molecules. PMID:22952831

  1. Determination of dissociation constants of pharmacologically active xanthones by capillary zone electrophoresis with diode array detection.

    PubMed

    Wu, Xiaomu; Gong, Suxuan; Bo, Tao; Liao, Yiping; Liu, Huwei

    2004-12-24

    In this article, the dissociation constants (pKa) of 10 pharmacologically active xanthones isolated from herbal medicine Securidaca inappendiculata were determined by capillary zone electrophoresis with diode array detection. The pKa values determined by the method based on the electrophoretic mobilities (calculated from migration times) have been proved by the method based on UV absorbance calculated from the online spectra corresponding peaks. No conspicuous difference was observed between the two methods with acceptable reproducibility. Two pKa values (pKa1 and pKa2) were found for four xanthones while generally the 10 compounds possess the pKa values ranging from 6.4 to 9.2. PMID:15641365

  2. Estimation of Nutation Time Constant Model Parameters for On-Axis Spinning Spacecraft

    NASA Technical Reports Server (NTRS)

    Schlee, Keith; Sudermann, James

    2008-01-01

    Calculating an accurate nutation time constant for a spinning spacecraft is an important step for ensuring mission success. Spacecraft nutation is caused by energy dissipation about the spin axis. Propellant slosh in the spacecraft fuel tanks is the primary source for this dissipation and can be simulated using a forced motion spin table. Mechanical analogs, such as pendulums and rotors, are typically used to simulate propellant slosh. A strong desire exists for an automated method to determine these analog parameters. The method presented accomplishes this task by using a MATLAB Simulink/SimMechanics based simulation that utilizes the Parameter Estimation Tool.

  3. Time constants and transfer functions for a homogeneous 900 MWt metallic fueled LMR

    SciTech Connect

    Grimm, K.N.; Meneghetti, D.

    1988-01-01

    Nodal transfer functions are calculated for a 900 MWt U10Zr-fueled sodium cooled reactor. From the transfer functions the time constants, feedback reactivity transfer function coefficients, and power coefficients can be determined. These quantities are calculated for core fuel, upper and lower axial reflector steel, radial blanket fuel, radial reflector steel, and B/sub 4/C rod shaft expansion effect. The quantities are compared to the analogous quantities of a 60 MWt metallic-fueled sodium cooled Experimental Breeder Reactor II configuration. 8 refs., 2 figs., 6 tabs.

  4. Oklo Constraint on the Time-Variabilityof the Fine-Structure Constant

    NASA Astrophysics Data System (ADS)

    Fujii, Yasunori

    The Oklo phenomenon, natural fission reactors which had taken place in Gabon about 2 billion years ago, provides one of the most stringent constraints on the possible time-variability of the fine-structure constant . We first review briefly what it is and how reliable it is in constraining . We then compare the result with a more recent result on the nonzero change of obtained from the observation of the QSO absorption lines. We suggest a possible way to make these results consistent with each other in terms of the behavior of a scalar field which is expected to be responsible for the acceleration of the universe.

  5. Developmental Times of Chrysomya megacephala (Fabricius) (Diptera: Calliphoridae) at Constant Temperatures and Applications in Forensic Entomology.

    PubMed

    Yang, Yong-Qiang; Li, Xue-Bo; Shao, Ru-Yue; Lyu, Zhou; Li, Hong-Wei; Li, Gen-Ping; Xu, Lyu-Zi; Wan, Li-Hua

    2016-09-01

    The characteristic life stages of infesting blowflies (Calliphoridae) such as Chrysomya megacephala (Fabricius) are powerful evidence for estimating the death time of a corpse, but an established reference of developmental times for local blowfly species is required. We determined the developmental rates of C. megacephala from southwest China at seven constant temperatures (16-34°C). Isomegalen and isomorphen diagrams were constructed based on the larval length and time for each developmental event (first ecdysis, second ecdysis, wandering, pupariation, and eclosion), at each temperature. A thermal summation model was constructed by estimating the developmental threshold temperature D0 and the thermal summation constant K. The thermal summation model indicated that, for complete development from egg hatching to eclosion, D0 = 9.07 ± 0.54°C and K = 3991.07 ± 187.26 h °C. This reference can increase the accuracy of estimations of postmortem intervals in China by predicting the growth of C. megacephala.

  6. Developmental Times of Chrysomya megacephala (Fabricius) (Diptera: Calliphoridae) at Constant Temperatures and Applications in Forensic Entomology.

    PubMed

    Yang, Yong-Qiang; Li, Xue-Bo; Shao, Ru-Yue; Lyu, Zhou; Li, Hong-Wei; Li, Gen-Ping; Xu, Lyu-Zi; Wan, Li-Hua

    2016-09-01

    The characteristic life stages of infesting blowflies (Calliphoridae) such as Chrysomya megacephala (Fabricius) are powerful evidence for estimating the death time of a corpse, but an established reference of developmental times for local blowfly species is required. We determined the developmental rates of C. megacephala from southwest China at seven constant temperatures (16-34°C). Isomegalen and isomorphen diagrams were constructed based on the larval length and time for each developmental event (first ecdysis, second ecdysis, wandering, pupariation, and eclosion), at each temperature. A thermal summation model was constructed by estimating the developmental threshold temperature D0 and the thermal summation constant K. The thermal summation model indicated that, for complete development from egg hatching to eclosion, D0 = 9.07 ± 0.54°C and K = 3991.07 ± 187.26 h °C. This reference can increase the accuracy of estimations of postmortem intervals in China by predicting the growth of C. megacephala. PMID:27581209

  7. Constant-time parallel sorting algorithm and its optical implementation using smart pixels

    NASA Astrophysics Data System (ADS)

    Louri, Ahmed; Hatch, James A., Jr.; Na, Jongwhoa

    1995-06-01

    Sorting is a fundamental operation that has important implications in a vast number of areas. For instance, sorting is heavily utilized in applications such as database machines, in which hashing techniques are used to accelerate data-processing algorithms. It is also the basis for interprocessor message routing and has strong implications in video telecommunications. However, high-speed electronic sorting networks are difficult to implement with VLSI technology because of the dense, global connectivity required. Optics eliminates this bottleneck by offering global interconnects, massive parallelism, and noninterfering communications. We present a parallel sorting algorithm and its efficient optical implementation. The algorithm sorts n data elements in few steps, independent of the number of elements to be sorted. Thus it is a constant-time sorting algorithm [i.e., O(1) time]. We also estimate the system's performance to show that the proposed sorting algorithm can provide at least 2 orders of magnitude improvement in execution time over conventional electronic algorithms.

  8. A Different Look at Dark Energy and the Time Variation of Fundamental Constants

    SciTech Connect

    Weinstein, Marvin; /SLAC

    2011-02-07

    This paper makes the simple observation that a fundamental length, or cutoff, in the context of Friedmann-Lemaitre-Robertson-Walker (FRW) cosmology implies very different things than for a static universe. It is argued that it is reasonable to assume that this cutoff is implemented by fixing the number of quantum degrees of freedom per co-moving volume (as opposed to a Planck volume) and the relationship of the vacuum-energy of all of the fields in the theory to the cosmological constant (or dark energy) is re-examined. The restrictions that need to be satisfied by a generic theory to avoid conflicts with current experiments are discussed, and it is shown that in any theory satisfying these constraints knowing the difference between w and minus one allows one to predict w. It is argued that this is a robust result and if this prediction fails the idea of a fundamental cutoff of the type being discussed can be ruled out. Finally, it is observed that, within the context of a specific theory, a co-moving cutoff implies a predictable time variation of fundamental constants. This is accompanied by a general discussion of why this is so, what are the strongest phenomenological limits upon this predicted variation, and which limits are in tension with the idea of a co-moving cutoff. It is pointed out, however, that a careful comparison of the predicted time variation of fundamental constants is not possible without restricting to a particular model field-theory and that is not done in this paper.

  9. Constant time tensor correlation experiments by non-gamma-encoded recoupling pulse sequences

    NASA Astrophysics Data System (ADS)

    Mou, Yun; Tsai, Tim W. T.; Chan, Jerry C. C.

    2012-10-01

    Constant-time tensor correlation under magic-angle spinning conditions is an important technique in solid-state nuclear magnetic resonance spectroscopy for the measurements of backbone or side-chain torsion angles of polypeptides and proteins. We introduce a general method for the design of constant-time tensor correlation experiments under magic-angle spinning. Our method requires that the amplitude of the average Hamiltonian must depend on all the three Euler angles bringing the principal axis system to the rotor-fixed frame, which is commonly referred to as non-gamma encoding. We abbreviate this novel approach as COrrelation of Non-Gamma-Encoded Experiment (CONGEE), which exploits the orientation-dependence of non-gamma-encoded sequences with respect to the magic-angle rotation axis. By manipulating the relative orientation of the average Hamiltonians created by two non-gamma-encoded sequences, one can obtain a modulation of the detected signal, from which the structural information can be extracted when the tensor orientations relative to the molecular frame are known. CONGEE has a prominent feature that the number of rf pulses and the total pulse sequence duration can be maintained to be constant so that for torsion angle determination the effects of systematic errors owing to the experimental imperfections and/or T2 effects could be minimized. As a proof of concept, we illustrate the utility of CONGEE in the correlation between the C' chemical shift tensor and the Cα-Hα dipolar tensor for the backbone psi angle determination. In addition to a detailed theoretical analysis, numerical simulations and experiments measured for [U-13C, 15N]-L-alanine and N-acetyl-[U-13C, 15N]-D,L-valine are used to validate our approach at a spinning frequency of 20 kHz.

  10. DEMETER Observations of Ionospheric Heating Time Constants Above the NWC VLF Transmitter

    NASA Astrophysics Data System (ADS)

    Bell, T. F.; Graf, K. L.; Inan, U. S.; Parrot, M.

    2011-12-01

    As demonstrated by recent DEMETER observations, intense 19.8 kHz VLF signals from the powerful (1 MW) NWC transmitter in Australia significantly heat the overlying ionosphere and produce significant changes in local electron and ion density and temperature at 700 km altitude [Parrot et al., 2007]. These changes are accompanied by a unique VLF plasma wave structure covering a 5 to 10 kHz band below the NWC signals and by quasi-electrostatic ELF turbulence. In order to determine the heating and cooling time constants of this effect, a campaign was carried out in which the NWC transmitter was programed to transmit a single CW pulse of 2 second duration every 10 seconds during periods in which the DEMETER spacecraft passed over the transmitter location. The data from this campaign show that the time constant for production of the unique VLF plasma wave structure and the quasi-electrostatic ELF turbulence ranged from 100 to 300 msec. However significant changes in electron and ion density and temperature during the 2 second pulses occurred only sporadically. This result suggests that small scale ( 10-100 m) plasma density irregularities are produced quickly by the heating pulses, but larger scale irregularities take significantly longer than 2 seconds to develop. We discuss the observations obtained during the campaign and the physical mechanisms involved in the heating process.

  11. Accelerating universe and the time-dependent fine-structure constant

    NASA Astrophysics Data System (ADS)

    Fujii, Yasunori

    2010-11-01

    I start with assuming a gravitational scalar field as the dark-energy supposed to be responsible for the accelerating universe. Also from the point of view of unification, a scalar field implies a time-variability of certain “constants” in Nature. In this context I once derived a relation for the time-variability of the fine-structure constant α: Δα/α =ζ Ƶ(α/π) Δσ, where ζ and Ƶ are the constants of the order one, while σ on the right-hand side is the scalar field in action in the accelerating universe. I use the reduced Planckian units with c=ℏ =MP(=(8π G)-1/2)=1. I then compared the dynamics of the accelerating universe, on one hand, and Δα/α derived from the analyses of QSO absorption lines, Oklo phenomenon, also different atomic clocks in the laboratories, on the other hand. I am here going to discuss the theoretical background of the relation, based on the scalar-tensor theory invented first by Jordan in 1955.

  12. The Effects of Constant Time Delay and Strategic Instruction on Students with Learning Disabilities' Maintenance and Generalization

    ERIC Educational Resources Information Center

    Flores, Margaret M.; Houchins, David E.; Shippen, Margaret E.

    2006-01-01

    The purpose of this series of case studies was to compare the impact of Constant Time Delay and Strategic Instruction on the maintenance and generalization of learning. Four middle school students with learning disabilities were effectively taught two different groups of multiplication facts using Constant Time Delay and Strategic instruction. The…

  13. Vestibular Compensation in Unilateral Patients Often Causes Both Gain and Time Constant Asymmetries in the VOR

    PubMed Central

    Ranjbaran, Mina; Katsarkas, Athanasios; Galiana, Henrietta L.

    2016-01-01

    The vestibulo-ocular reflex (VOR) is essential in our daily life to stabilize retinal images during head movements. Balanced vestibular functionality secures optimal reflex performance which otherwise can be distorted by peripheral vestibular lesions. Luckily, vestibular compensation in different neuronal sites restores VOR function to some extent over time. Studying vestibular compensation gives insight into the possible mechanisms for plasticity in the brain. In this work, novel experimental analysis tools are employed to reevaluate the VOR characteristics following unilateral vestibular lesions and compensation. Our results suggest that following vestibular lesions, asymmetric performance of the VOR is not only limited to its gain. Vestibular compensation also causes asymmetric dynamics, i.e., different time constants for the VOR during leftward or rightward passive head rotation. Potential mechanisms for these experimental observations are provided using simulation studies. PMID:27065839

  14. Vestibular Compensation in Unilateral Patients Often Causes Both Gain and Time Constant Asymmetries in the VOR.

    PubMed

    Ranjbaran, Mina; Katsarkas, Athanasios; Galiana, Henrietta L

    2016-01-01

    The vestibulo-ocular reflex (VOR) is essential in our daily life to stabilize retinal images during head movements. Balanced vestibular functionality secures optimal reflex performance which otherwise can be distorted by peripheral vestibular lesions. Luckily, vestibular compensation in different neuronal sites restores VOR function to some extent over time. Studying vestibular compensation gives insight into the possible mechanisms for plasticity in the brain. In this work, novel experimental analysis tools are employed to reevaluate the VOR characteristics following unilateral vestibular lesions and compensation. Our results suggest that following vestibular lesions, asymmetric performance of the VOR is not only limited to its gain. Vestibular compensation also causes asymmetric dynamics, i.e., different time constants for the VOR during leftward or rightward passive head rotation. Potential mechanisms for these experimental observations are provided using simulation studies. PMID:27065839

  15. Quantitative Analysis of Metabolic Mixtures by 2D 13C-Constant-Time TOCSY NMR Spectroscopy

    PubMed Central

    Bingol, Kerem; Zhang, Fengli; Bruschweiler-Li, Lei; Brüschweiler, Rafael

    2013-01-01

    An increasing number of organisms can be fully 13C-labeled, which has the advantage that their metabolomes can be studied by high-resolution 2D NMR 13C–13C constant-time (CT) TOCSY experiments. Individual metabolites can be identified via database searching or, in the case of novel compounds, through the reconstruction of their backbone-carbon topology. Determination of quantitative metabolite concentrations is another key task. Because significant peak overlaps in 1D NMR spectra prevents straightforward quantification through 1D peak integrals, we demonstrate here the direct use of 13C–13C CT-TOCSY spectra for metabolite quantification. This is accomplished through the quantum-mechanical treatment of the TOCSY magnetization transfer at short and long mixing times or by the use of analytical approximations, which are solely based on the knowledge of the carbon-backbone topologies. The methods are demonstrated for carbohydrate and amino-acid mixtures. PMID:23773204

  16. Effects of magnetic dipolar interactions on the specific time constant in superparamagnetic nanoparticle systems

    NASA Astrophysics Data System (ADS)

    Iacob, N.; Schinteie, G.; Bartha, C.; Palade, P.; Vekas, L.; Kuncser, V.

    2016-07-01

    A quantitative treatment of the effects of magnetic mutual interactions on the specific absorption rate of a superparamagnetic system of iron oxide nanoparticles coated with oleic acid is reported. The nanoparticle concentration of the considered ferrofluid samples varied from a very low (0.005) to a medium (0.16) value of the volume fraction, whereas the amplitude of the exciting AC magnetic field ranged from 14–35 kA m‑1. It was proved that a direct effect of the interparticle interactions resides in the regime of the modified superparamagnetism, dealing, besides the usual increase in the anisotropy energy barrier per nanoparticle, with the decrease in the specific time constant {τ0} of the relaxation law, usually considered as a material constant. Consequently, the increase in the specific absorption rate versus the volume fraction is significantly diminished in the presence of the interparticle interactions compared to the case of non-interacting superparamagnetic nanoparticles, with direct influence on the magnetic hyperthermia efficiency.

  17. Second order rate constants for intramolecular conversions: Application to gas-phase NMR relaxation times

    NASA Astrophysics Data System (ADS)

    Bauer, S. H.; Lazaar, K. I.

    1983-09-01

    The usually quoted expression for the second order rate constant, for a unimolecular reaction at the low pressure limit, is valid only for strictly irreversible processes. Its application to isomerization reactions (which are to some extent reversible) is demonstrably in error; corrected expressions have been published. Attention is directed to intramolecular conversions over low barriers, for which the inappropriateness of the unidirectional expression becomes obvious. For such isomerizations we propose a model which incorporates only operationally observable states, so that an essential conceptual ambiguity is avoided. Use of this model is illustrated for the syn⇄anti conversions of methyl nitrite, derived from a gas phase NMR coalescence curve (Mc:Tc). The present data suggest that during isomerization the alkyl nitrites may not be completely ergodic on a time scale of 10-9 s. A regional phase-space model is proposed which has the appropriate formalism to account for this behavior.

  18. Constraints on the Time Variation of the Fine Structure Constant by the 5-Year WMAP Data

    NASA Astrophysics Data System (ADS)

    Nakashima, M.; Nagata, R.; Yokoyama, J.

    2008-12-01

    The constraints on the time variation of the fine structure constant at recombination epoch relative to its present value, Δα/α ≡ (α_{rec} - α_{now})/α_{now}, are obtained from the analysis of the 5-year WMAP cosmic microwave background data. As a result of Markov-Chain Monte-Carlo analysis, it is found that, contrary to the analysis based on the previous WMAP data, the mean value of Δα/α = -0.0009 does not change significantly whether we use the Hubble Space Telescope (HST) measurement of the Hubble parameter as a prior or not. The resultant 95% confidence ranges of Δα/α are -0.028 < Δα/α < 0.026 with HST prior and -0.050 < Δα/α < 0.042 without HST prior.

  19. Time constant of defect relaxation in ion-irradiated 3C-SiC

    SciTech Connect

    Wallace, J. B.; Bayu Aji, L. B.; Kucheyev, S. O.; Shao, L.

    2015-05-18

    Above room temperature, the buildup of radiation damage in SiC is a dynamic process governed by the mobility and interaction of ballistically generated point defects. Here, we study the dynamics of radiation defects in 3C-SiC bombarded at 100 °C with 500 keV Ar ions, with the total ion dose split into a train of equal pulses. Damage–depth profiles are measured by ion channeling for a series of samples irradiated under identical conditions except for different durations of the passive part of the beam cycle. Results reveal an effective defect relaxation time constant of ∼3 ms (for second order kinetics) and a dynamic annealing efficiency of ∼40% for defects in both Si and C sublattices. This demonstrates a crucial role of dynamic annealing at elevated temperatures and provides evidence of the strong coupling of defect accumulation processes in the two sublattices of 3C-SiC.

  20. Precision Measurements: Testing the Time Variation of the Fine Structure Constant

    NASA Astrophysics Data System (ADS)

    Lamoreaux, Steve

    2004-05-01

    Often, precision measurements from diverse fields can be used to learn new facts about the universe. The usual definition of "precision" is based on improvements over previous measurements. A review of the present state of knowledge regarding the possible time variation of the fine structure constant α will be presented; "precise" data from natural phenomena, which include an apparent shift in the red-shift-scaled fine structure in the absorption spectra of quasar light, and the isotopic abundances in the fission products of a prehistoric natural reactor in Oklo, Gabon. Prospects to improve the accuracy for the constancy of α with laboratory experiments will be discussed. Our two experimental investigations currently being developed are based on optical spectroscopy of trapped ions and on radiofrequency spectroscopy of an atomic dysprosium beam. A sensitivity of dotα/α≈ 10-18/yr is anticipated. Because this accuracy exceeds that by which the second is defined, these measurements will necessarily be differential.

  1. Determination of the Newtonian Gravitational Constant G with Time-of-Swing Method

    SciTech Connect

    Luo Jun; Liu Qi; Tu Liangcheng; Shao Chenggang; Liu Linxia; Yang Shanqing; Li Qing; Zhang Yating

    2009-06-19

    We present a new value of the Newtonian gravitational constant G by using the time-of-swing method. Several improvements greatly reduce the uncertainties: (1) measuring the anelasticity of the fiber directly; (2) using spherical source masses minimizes the effects of density inhomogeneity and eccentricities; (3) using a quartz block pendulum simplifies its vibration modes and minimizes the uncertainty of inertial moment; (4) setting the pendulum and source masses both in a vacuum chamber reduces the error of measuring the relative positions. By two individual experiments, we obtain G=6.673 49(18)x10{sup -11} m{sup 3} kg{sup -1} s{sup -2} with a standard uncertainty of about 2.6 parts in 10{sup 5}.

  2. Bilateral control of master-slave manipulators with constant time delay.

    PubMed

    Forouzantabar, A; Talebi, H A; Sedigh, A K

    2012-01-01

    This paper presents a novel teleoperation controller for a nonlinear master-slave robotic system with constant time delay in communication channel. The proposed controller enables the teleoperation system to compensate human and environmental disturbances, while achieving master and slave position coordination in both free motion and contact situation. The current work basically extends the passivity based architecture upon the earlier work of Lee and Spong (2006) [14] to improve position tracking and consequently transparency in the face of disturbances and environmental contacts. The proposed controller employs a PID controller in each side to overcome some limitations of a PD controller and guarantee an improved performance. Moreover, by using Fourier transform and Parseval's identity in the frequency domain, we demonstrate that this new PID controller preserves the passivity of the system. Simulation and semi-experimental results show that the PID controller tracking performance is superior to that of the PD controller tracking performance in slave/environmental contacts.

  3. A multiple relaxation time extension of the constant speed kinetic model

    NASA Astrophysics Data System (ADS)

    Zadehgol, Abed; Ashrafizaadeh, Mahmud

    2016-02-01

    In this work, a multiple relaxation time (MRT) extension of the recently introduced constant speed kinetic model (CSKM) is proposed. The CSKM, which is an entropic kinetic model and based on unconventional entropies of Burg and Tssalis, was introduced in [A. Zadehgol and M. Ashrafizaadeh, J. Comput. Phys. 274, 803 (2014)]; [A. Zadehgol Phys. Rev. E 91, 063311 (2015)] as an extension of the model of Boghosian et al. [Phys. Rev. E 68, 025103 (2003)] in the limit of fixed speed continuous velocities. The present extension improves the stability of the previous models at very high Reynolds numbers, while allowing for a more convenient orthogonal lattice. The model is verified by solving the following benchmark problems: (i) the lid driven square cavity and (ii) the Kelvin-Helmholtz instability of thin shear layers in a doubly periodic square domain.

  4. Effects of high-frequency emphasis and compression time constants on speech intelligibility in noise.

    PubMed

    van Toor, Thijs; Verschuure, Hans

    2002-10-01

    The objectives of the study were to evaluate the effect of different settings with regard to speech intelligibility in noise both objectively and subjectively and thus determine a favoured setting of compression time parameters, pre-set program (high-frequency emphasis) or combination for each individual user in a prospective study. Another objective was to evaluate the relationship between patient characteristics (e.g. slope of hearing loss) and favoured settings. In total, 38 subjects divided over five audiological centres were fitted with the Philips Spaceline D71-40 BTE digital hearing aid. Subjects were asked to compare three predefined compression algorithms with different time constants, slow (indicated by the manufacturer as AVC), intermediate (NORMAL) and fast (SYLLABIC) over two 4-week periods using the intermediate setting in both comparisons and randomizing over the fast and slow conditions. A randomization determined whether a subject started with the comfort-oriented pre-set program (AUTO) or the speech intelligibility-oriented setting with high-frequency emphasis (SPIN). In a third 4-week period, the pre-sets AUTO and SPIN were compared using the setting of the compression time constants that gave the best results during the first two periods. Comparisons were made using a standard speech-in-noise test with three types of noise: continuous speaker noise, modulated ICRA-4 noise, and car noise. The patients were also asked to fill in a Dutch translation and adaptation of the APHAB questionnaire to indicate their impression of performance. The results indicate that no compression algorithm, pre-set or combination is favoured overall. The largest improvement in speech-in-noise scores was found with syllabic compression. The advantageous effect of high-frequency emphasis after optimization of compression timing is small. The APHAB showed that users tend to prefer the SPIN setting. We found no relationship between favoured compression or pre-set and the

  5. Effect of temporal acquisition parameters on image quality of strain time constant elastography.

    PubMed

    Nair, Sanjay; Varghese, Joshua; Chaudhry, Anuj; Righetti, Raffaella

    2015-04-01

    Ultrasound methods to image the time constant (TC) of elastographic tissue parameters have been recently developed. Elastographic TC images from creep or stress relaxation tests have been shown to provide information on the viscoelastic and poroelastic behavior of tissues. However, the effect of temporal ultrasonic acquisition parameters and input noise on the image quality of the resultant strain TC elastograms has not been fully investigated yet. Understanding such effects could have important implications for clinical applications of these novel techniques. This work reports a simulation study aimed at investigating the effects of varying windows of observation, acquisition frame rate, and strain signal-to-noise ratio (SNR) on the image quality of elastographic TC estimates. A pilot experimental study was used to corroborate the simulation results in specific testing conditions. The results of this work suggest that the total acquisition time necessary for accurate strain TC estimates has a linear dependence to the underlying strain TC (as estimated from the theoretical strain-vs.-time curve). The results also indicate that it might be possible to make accurate estimates of the elastographic TC (within 10% error) using windows of observation as small as 20% of the underlying TC, provided sufficiently fast acquisition rates (>100 Hz for typical acquisition depths). The limited experimental data reported in this study statistically confirm the simulation trends, proving that the proposed model can be used as upper bound guidance for the correct execution of the experiments.

  6. Stability and Relative Stability of Linear Systems with Many Constant Time Delays. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Barker, Larry Keith

    1976-01-01

    A method of determining the stability of linear systems with many constant time delays is developed. This technique, an extension of the tau-decomposition method, is used to examine not only the stability but also the relative stability of retarded systems with many delays and a class of neutral equations with one delay. Analytical equations are derived for partitioning the delay space of a retarded system with two time delays. The stability of the system in each of the regions defined by the partitioning curves in the parameter plane is determined using the extended tau-decomposition method. In addition, relative stability boundaries are defined using the extended tau-decompositon method in association with parameter plane techniques. Several applications of the extended tau-decomposition method are presented and compared with stability results obtained from other analyses. In all cases the results obtained using the method outlined herein coincide with and extend those of previous investigations. The extended tau-decomposition method applied to systems with time delays requires less computational effort and yields more complete stability analyses than previous techniques.

  7. Melatonin administration modifies circadian motor activity under constant light depending on the lighting conditions during suckling.

    PubMed

    Carpentieri, Agata R; Oliva, Clara; Díez-Noguera, Antoni; Cambras, Trinitat

    2015-01-01

    Early lighting conditions have been described to produce long-term effects on circadian behavior, which may also influence the response to agents acting on the circadian system. It has been suggested that melatonin (MEL) may act on the circadian pacemaker and as a scavenger of reactive oxygen and nitrogen species. Here, we studied the oxidative and behavioral changes caused by prolonged exposure to constant light (LL) in groups of rats that differed in MEL administration and in lighting conditions during suckling. The rats were exposed to either a light-dark cycle (LD) or LL. At 40 days old, rats were treated for 2 weeks with a daily subcutaneous injection of MEL (10 mg/kg body weight) or a vehicle at activity onset. Blood samples were taken before and after treatment, to determine catalase (CAT) activity and nitrite level in plasma. As expected, LL-reared rats showed a more stable motor activity circadian rhythm than LD rats. MEL treatment produced more reactivity in LD- than in LL rats, and was also able to alter the phase of the rhythm in LD rats. There were no significant differences in nitrite levels or CAT activity between the groups, although both variables increased with time. Finally, we also tested depressive signs by means of sucrose consumption, and anhedonia was found in LD males treated with MEL. The results suggest that the lighting conditions in early infancy are important for the long-term functionality of the circadian system, including rhythm manifestation, responses to MEL and mood alterations.

  8. Achieving what cannot be done: coping with the time constants in a dynamic decision task by doing something else.

    PubMed

    Brehmer, Berndt; Nählinder, Staffan

    2007-10-01

    This study examines how people handle the time constants in dynamic decision tasks, using a microworld called NEWFIRE which simulates forest fire fighting. The results showed that the participants did not adapt to the time constants, as shown by the fact that they did not discriminate between fires requiring different number of fire fighting units when varying the number of fire fighting units was a means of compensating for the time constants. If they were allowed to move units before the fire started their performance improved, suggesting that they could compensate for their problems with the time constants by restructuring the task in such a way that they did not need to consider them. It is suggested that such restructuring may well be how people handle dynamic tasks also in other circumstances, and that more effort should be put into studying what people actually do in dynamic tasks, rather than into only assessing whether or not they perform optimally.

  9. CONVERGENCE STUDIES OF MASS TRANSPORT IN DISKS WITH GRAVITATIONAL INSTABILITIES. I. THE CONSTANT COOLING TIME CASE

    SciTech Connect

    Michael, Scott; Steiman-Cameron, Thomas Y.; Durisen, Richard H.; Boley, Aaron C. E-mail: tomsc@astro.indiana.edu E-mail: aaron.boley@gmail.com

    2012-02-10

    We conduct a convergence study of a protostellar disk, subject to a constant global cooling time and susceptible to gravitational instabilities (GIs), at a time when heating and cooling are roughly balanced. Our goal is to determine the gravitational torques produced by GIs, the level to which transport can be represented by a simple {alpha}-disk formulation, and to examine fragmentation criteria. Four simulations are conducted, identical except for the number of azimuthal computational grid points used. A Fourier decomposition of non-axisymmetric density structures in cos (m{phi}), sin (m{phi}) is performed to evaluate the amplitudes A{sub m} of these structures. The A{sub m} , gravitational torques, and the effective Shakura and Sunyaev {alpha} arising from gravitational stresses are determined for each resolution. We find nonzero A{sub m} for all m-values and that A{sub m} summed over all m is essentially independent of resolution. Because the number of measurable m-values is limited to half the number of azimuthal grid points, higher-resolution simulations have a larger fraction of their total amplitude in higher-order structures. These structures act more locally than lower-order structures. Therefore, as the resolution increases the total gravitational stress decreases as well, leading higher-resolution simulations to experience weaker average gravitational torques than lower-resolution simulations. The effective {alpha} also depends upon the magnitude of the stresses, thus {alpha}{sub eff} also decreases with increasing resolution. Our converged {alpha}{sub eff} is consistent with predictions from an analytic local theory for thin disks by Gammie, but only over many dynamic times when averaged over a substantial volume of the disk.

  10. Time activities at the BIPM

    NASA Technical Reports Server (NTRS)

    Thomas, Claudine

    1995-01-01

    The generation and dissemination of International Atomic Time, TAI, and of Coordinated Universal Time, UTC, are explicitly mentioned in the list of the principal tasks of the BIPM, recalled in the Comptes Rendus of the 18th Conference Generale des Poids et Mesures, in 1987. These tasks are fulfilled by the BIPM Time Section, thanks to international cooperation with national timing centers, which maintain, under metrological conditions, the clocks used to generate TAI. Besides the current work of data collection and processing, research activities are carried out in order to adapt the computation of TAI to the most recent improvements occurring in the time and frequency domains. Studies concerning the application of general relativity and pulsar timing to time metrology are also actively pursued. This paper summarizes the work done in all these fields and outlines future projects.

  11. Characterization of the Dielectric Constant in the Trichoderma reesei Cel7B Active Site.

    PubMed

    Song, Xiangfei; Wang, Yefei; Zhang, Shujun; Yan, Shihai; Li, Tong; Yao, Lishan

    2015-07-27

    An attempt is made to evaluate the dielectric constant of the Trichoderma reesei Cel7B active site. Through kinetic measurements, the pKa value of the catalytic acid E201 is determined. Mutations (away from E201) with net charge changes are introduced to perturb the E201 pKa. It is shown that the mutation with a +1 charge change (including G225R, G230R, and A335R) decreases the pKa of E201, whereas the mutation with a -1 charge change (including Q149E, A222D, G225D, and G230D) increases the pKa. This effect is consistent with the electrostatic interaction between the changed charge and the E201 side chain. The fitting of the experimental data yields an apparent dielectric constant of 25-80. Molecular dynamics simulations with explicit water molecules indicate that the high solvent accessibility of the active site contributes largely to the high dielectric constant. ONIOM calculations show that high dielectric constant benefits the catalysis through decreasing the energy of the transition state relative to that of the enzyme substrate complex. PMID:26114648

  12. Characterization of the Dielectric Constant in the Trichoderma reesei Cel7B Active Site.

    PubMed

    Song, Xiangfei; Wang, Yefei; Zhang, Shujun; Yan, Shihai; Li, Tong; Yao, Lishan

    2015-07-27

    An attempt is made to evaluate the dielectric constant of the Trichoderma reesei Cel7B active site. Through kinetic measurements, the pKa value of the catalytic acid E201 is determined. Mutations (away from E201) with net charge changes are introduced to perturb the E201 pKa. It is shown that the mutation with a +1 charge change (including G225R, G230R, and A335R) decreases the pKa of E201, whereas the mutation with a -1 charge change (including Q149E, A222D, G225D, and G230D) increases the pKa. This effect is consistent with the electrostatic interaction between the changed charge and the E201 side chain. The fitting of the experimental data yields an apparent dielectric constant of 25-80. Molecular dynamics simulations with explicit water molecules indicate that the high solvent accessibility of the active site contributes largely to the high dielectric constant. ONIOM calculations show that high dielectric constant benefits the catalysis through decreasing the energy of the transition state relative to that of the enzyme substrate complex.

  13. New determination of the gravitational constant G with time-of-swing method

    SciTech Connect

    Tu Liangcheng; Li Qing; Wang Qinglan; Shao Chenggang; Yang Shanqing; Liu Linxia; Liu Qi; Luo Jun

    2010-07-15

    A new determination of the Newtonian gravitational constant G is presented by using a torsion pendulum with the time-of-swing method. Compared with our previous measurement with the same method, several improvements greatly reduced the uncertainties as follows: (i) two stainless steel spheres with more homogeneous density are used as the source masses instead of the cylinders used in the previous experiment, and the offset of the mass center from the geometric center is measured and found to be much smaller than that of the cylinders; (ii) a rectangular glass block is used as the main body of the pendulum, which has fewer vibration modes and hence improves the stability of the period and reduces the uncertainty of the moment of inertia; (iii) both the pendulum and source masses are placed in the same vacuum chamber to reduce the error of measuring the relative positions; (iv) changing the configurations between the ''near'' and ''far'' positions is remotely operated by using a stepper motor to lower the environmental disturbances; and (v) the anelastic effect of the torsion fiber is first measured directly by using two disk pendulums with the help of a high-Q quartz fiber. We have performed two independent G measurements, and the two G values differ by only 9 ppm. The combined value of G is (6.673 49{+-}0.000 18)x10{sup -11} m{sup 3} kg{sup -1} s{sup -2} with a relative uncertainty of 26 ppm.

  14. Automated Method for Estimating Nutation Time Constant Model Parameters for Spacecraft Spinning on Axis

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Calculating an accurate nutation time constant (NTC), or nutation rate of growth, for a spinning upper stage is important for ensuring mission success. Spacecraft nutation, or wobble, is caused by energy dissipation anywhere in the system. Propellant slosh in the spacecraft fuel tanks is the primary source for this dissipation and, if it is in a state of resonance, the NTC can become short enough to violate mission constraints. The Spinning Slosh Test Rig (SSTR) is a forced-motion spin table where fluid dynamic effects in full-scale fuel tanks can be tested in order to obtain key parameters used to calculate the NTC. We accomplish this by independently varying nutation frequency versus the spin rate and measuring force and torque responses on the tank. This method was used to predict parameters for the Genesis, Contour, and Stereo missions, whose tanks were mounted outboard from the spin axis. These parameters are incorporated into a mathematical model that uses mechanical analogs, such as pendulums and rotors, to simulate the force and torque resonances associated with fluid slosh.

  15. Cerebral Arterial Time Constant Recorded from the MCA and PICA in Normal Subjects.

    PubMed

    Kasprowicz, Magdalena; Czosnyka, Marek; Poplawska, Karolina; Reinhard, Matthias

    2016-01-01

    Cerebral arterial time constant (τ) estimates how quickly the cerebral arterial bed distal to the point of insonation is filled with arterial blood following a cardiac contraction. It is not known how τ behaves in different vascular territories in the brain. We therefore investigated the differences in τ of two cerebral arteries: the posterior inferior cerebellar artery (PICA) and the middle cerebral artery (MCA).Transcranial Doppler cerebral blood flow velocity (CBFV) in the PICA and left MCA along with Finapres arterial blood pressure (ABP) were simultaneously recorded in 35 young healthy volunteers. τ was estimated using mathematical transformations of pulse waveforms of ABP and the CBFV of the MCA and the PICA. Since τ is independent from the vessel radius, its comparison in different cerebral arteries was feasible. Mean ABP was 76.1 ± 9.6 mmHg. The CBFV of the MCA was higher than that of the PICA (59.7 ± 7.7 vs. 41.0 ± 4.5 cm/s; p < 0.000001). τ of the PICA was shorter than that of the MCA (0.15 ± 0.03 vs. 0.18 ± 0.03 s; p < 0.000001). The MCA-supplied vascular bed has a longer distal average length, measured from the place of insonation up to the small arterioles, than the PICA-supplied vascular bed. Therefore, a longer time is needed to fill it with arterial blood volume. This study thus confirms the physiological validity of the τ concept. PMID:27165908

  16. Properties of human motor units after prolonged activity at a constant firing rate.

    PubMed

    Johnson, K V B; Edwards, S C; Van Tongeren, C; Bawa, P

    2004-02-01

    The primary purpose of this study was to examine if there are changes in the intrinsic properties of spinal motoneurons after prolonged submaximal contractions. To do this, we assessed whether or not the synaptic drive to motoneurons needs to increase in order to maintain a constant firing rate of a motor unit. Recruitment of new units and an increase in total electromyographic (EMG) activity of the muscle of interest were taken as estimates of an increase in synaptic drive. Subjects were asked to maintain a constant firing rate of a clearly identifiable (targeted) motor unit from the first dorsal interosseous muscle for approximately 10 min, while surface EMG and force were recorded simultaneously. For the 60 units studied, the duration of the constant-firing-rate period ranged from 73 to 1,140 s (448 +/- 227 s; mean +/- SD). There was a significant increase ( t-test, p<0.001) in the magnitude of mean surface EMG, and DC force while the targeted motoneuron maintained a constant rate suggesting an increase in the net excitatory input to the motoneuron pool. Changes occurring simultaneously in other parameters, namely, variability in interspike interval, magnitude of force fluctuations, the duration of motor unit action potentials, and the median power frequency of surface EMG were also computed. The firing rates of 16 concurrently firing motoneurons, not controlled by the subject, remained constant. The key finding of this study is that after prolonged activity, a motoneuron requires a stronger excitatory input to maintain its firing rate. Additional results are indicative of significant changes in the characteristics of the synaptic inputs, changes at the neuromuscular junction (both pre- and postsynaptic regions) and the sarcolemma.

  17. Estimation of the rate constants associated with the inhibitory effect of okadaic acid on type 2A protein phosphatase by time-course analysis.

    PubMed Central

    Takai, A; Ohno, Y; Yasumoto, T; Mieskes, G

    1992-01-01

    As is often the case with tightly binding inhibitors, okadaic acid produces its inhibitory effect on type 2A protein phosphatase (PP2A) in a time-dependent manner. We measured the rate constants associated with the binding of okadaic acid to PP2A by analysing the time-course of the reduction of the p-nitrophenyl phosphate (pNPP) phosphatase activity of the enzyme after application of okadaic acid. The rate constants for dissociation of okadaic acid from PP2A were also estimated from the time-course of the recovery of the activity from inhibition by okadaic acid after addition of a mouse IgG1 monoclonal antibody raised against the inhibitor. Our results show that the rate constants for the binding of okadaic acid and PP2A are of the order of 10(7) M-1.s-1, a typical value for reactions involving relatively large molecules, whereas those for their dissociation are in the range 10(-4)-10(-3) s-1. The very low values of the latter seems to be the determining factor for the exceedingly high affinity of okadaic acid for PP2A. The dissociation constants for the interaction of okadaic acid with the free enzyme and the enzyme-substrate complex, estimated as the ratio of the rate constants, are both in the range 30-40 pM, in agreement with the results of previous dose-inhibition analyses. PMID:1329723

  18. Bayesian Estimation of the Active Concentration and Affinity Constants Using Surface Plasmon Resonance Technology.

    PubMed

    Feng, Feng; Kepler, Thomas B

    2015-01-01

    Surface plasmon resonance (SPR) has previously been employed to measure the active concentration of analyte in addition to the kinetic rate constants in molecular binding reactions. Those approaches, however, have a few restrictions. In this work, a Bayesian approach is developed to determine both active concentration and affinity constants using SPR technology. With the appropriate prior probabilities on the parameters and a derived likelihood function, a Markov Chain Monte Carlo (MCMC) algorithm is applied to compute the posterior probability densities of both the active concentration and kinetic rate constants based on the collected SPR data. Compared with previous approaches, ours exploits information from the duration of the process in its entirety, including both association and dissociation phases, under partial mass transport conditions; do not depend on calibration data; multiple injections of analyte at varying flow rates are not necessary. Finally the method is validated by analyzing both simulated and experimental datasets. A software package implementing our approach is developed with a user-friendly interface and made freely available. PMID:26098764

  19. Does Newton’s gravitational constant vary sinusoidally with time? Orbital motions say no

    NASA Astrophysics Data System (ADS)

    Iorio, Lorenzo

    2016-02-01

    A sinusoidally time-varying pattern of the values of Newton’s constant of gravitation G measured in Earth-based laboratories over the last few decades has been recently reported in the literature. We put to the test the hypothesis that the aforementioned harmonic variation may pertain to G itself in a direct and independent way. We numerically integrated the ad hoc modified equations of motion of the major bodies of the Solar System, finding that the orbits of the planets would be altered by an unacceptably larger amount in view of the present-day high accuracy astrometric measurements. In the case of Saturn, its geocentric right ascension α, declination δ and range ρ would be affected by up to {10}4-{10}5 milliarcseconds and 105 km, respectively; the present-day residuals of such observables are as little as about 4 milliarcseconds and 10-1 km, respectively. We analytically calculated the long-term orbital effects induced by the putative harmonic variation of G at hand, finding non-zero rates of change for the semimajor axis a, the eccentricity e and the argument of pericenter ω of a test particle. For the LAGEOS satellite, an orbital increase as large as 3.9 m yr-1 is predicted, in contrast with the observed decay of -0.203 ± 0.035 m yr-1. An anomalous perihelion precession as large as 14 arcseconds per century is implied for Saturn, while latest observations constrain it to the 10-4 arcseconds per century level. The rejection level provided by the Mercury’s perihelion rate is of the same order of magnitude.

  20. Conditioned reinforcement in chain schedules when time to reinforcement is held constant.

    PubMed

    Bell, Matthew C; Williams, Ben A

    2013-03-01

    Two alternative approaches describe determinants of responding to a stimulus temporally distant from primary reinforcement. One emphasizes the temporal relation of each stimulus to the primary reinforcer, with relative proximity of the stimulus determining response rate. A contrasting view emphasizes immediate consequences of responding to the stimulus, the key factor being the conditioned reinforcement value of those immediate consequences. To contrast these approaches, 4 pigeons were exposed to a two-component multiple schedule with three-link chain schedules in each component. Only middle-link stimuli differed between chains. Baseline reinforcement probabilities were 0.50 for both chains; during discrimination phases it was 1.0 for one chain and 0.0 for the other. During discrimination phases pigeons responded more to the reinforcement-correlated middle link than to the extinction-correlated middle link, demonstrating that responding was affected by the probability change. Terminal link responding was also higher in the reinforced chain, even though the terminal link stimulus was identical in both chains. Of greatest interest is initial link responding, which was temporally most distant from reinforcement. Initial link responding, necessarily equal in the two chains, was significantly higher during the 1.0/0.0 discrimination phases, even though overall reinforcement probability remained constant. For 3 of 4 birds, in fact, initial-link response rates were higher than terminal-link response rates, an outcome that can be ascribed only to the potent conditioned reinforcement properties of the middle-link stimulus during the discrimination phases. Results are incompatible with any account of chain behavior based solely on relative time to reinforcement.

  1. Thermoelectric properties of bismuth telluride nanowires in the constant relaxation-time approximation

    NASA Astrophysics Data System (ADS)

    Bejenari, I.; Kantser, V.

    2008-09-01

    Electronic structure of bismuth telluride nanowires with the growth directions [110] and [015] is studied in the framework of the anisotropic effective-mass method using the parabolic band approximation. The components of the electron and hole effective-mass tensors for six valleys are calculated for both growth directions. For a square nanowire, in the temperature range from 77 to 500 K, the dependence of the Seebeck coefficient S , the thermal κ , and electrical conductivity σ , as well as the figure of merit ZT on the nanowire thickness and on the excess hole concentration pex , are investigated in the constant relaxation-time approximation. The carrier confinement is shown to play essential role for nanowires with cross section less than 30×30nm2 . In contrast to the excess holes (impurities), the confinement decreases both the carrier concentration and the thermal conductivity but increases the maximum value of the Seebeck coefficient. The confinement effect is stronger for the direction [015] than for the direction [110] due to the carrier mass difference for these directions. In the restricted temperature range, the size quantum limit is valid when the P -type nanowire cross section is smaller than 8×10nm2 ( 6×7 and 5×5nm2 ) at the excess hole concentration pex=2×1018cm-3 ( pex=5×1018cm-3 and pex=1×1019cm-3 correspondingly). The carrier confinement increases the maximum value of ZT and shifts it toward high temperatures. For the growth direction [110], the maximum value of the figure of merit for the P -type nanowire is equal to 1.4, 1.6, and 2.8, correspondingly, at temperatures 310, 390, and 480 K and the cross sections 30×30 , 15×15 , and 7×7nm2 (pex=5×1018cm-3) . At room temperature, the figure of merit equals 1.2, 1.3, and 1.7, respectively.

  2. Are Fundamental Constants Really Constant?

    ERIC Educational Resources Information Center

    Swetman, T. P.

    1972-01-01

    Dirac's classical conclusions, that the values of e2, M and m are constants and the quantity of G decreases with time. Evoked considerable interest among researchers and traces historical development by which further experimental evidence points out that both e and G are constant values. (PS)

  3. An Evaluation of Constant Time Delay and Simultaneous Prompting Procedures in Skill Acquisition for Young Children with Autism

    ERIC Educational Resources Information Center

    Brandt, Julie A. Ackerlund; Weinkauf, Sara; Zeug, Nicole; Klatt, Kevin P.

    2016-01-01

    Previous research has shown that various prompting procedures are effective in teaching skills to children and adults with developmental disabilities. Simultaneous prompting includes proving a prompt immediately following an instruction; whereas constant time-delay procedures include a set time delay (i.e., 5 s or 10 s) prior to delivering a…

  4. Variation of fundamental constants in space and time: Theory and observations

    NASA Astrophysics Data System (ADS)

    Flambaum, V. V.

    2008-10-01

    Review of recent works devoted to the temporal and spatialvariation of the fundamental constants and dependence of the fundamentalconstants on the gravitational potential (violation of local position invariance) is presented. We discuss the variation of the fine structure constant α=e2/ħc, strong interaction andfundamental masses (Higgs vacuum), e.g. the electron-to-proton mass ratioμ=me/Mp or Xe=me/ΛQCD and Xq=mq/ΛQCD.We also present new results from Big Bang nucleosynthesisand Oklo natural nuclear reactor data and propose new measurements of enhanced effects in atoms, nuclei and molecules, both in quasar and laboratory spectra.

  5. Analysis of constant tension-induced rupture of lipid membranes using activation energy.

    PubMed

    Karal, Mohammad Abu Sayem; Levadnyy, Victor; Yamazaki, Masahito

    2016-05-11

    The stretching of biomembranes and lipid membranes plays important roles in various physiological and physicochemical phenomena. Here we analyzed the rate constant kp of constant tension-induced rupture of giant unilamellar vesicles (GUVs) as a function of tension σ using their activation energy Ua. To determine the values of kp, we applied constant tension to a GUV membrane using the micropipette aspiration method and observed the rupture of GUVs, and then analyzed these data statistically. First, we investigated the temperature dependence of kp for GUVs of charged lipid membranes composed of negatively charged dioleoylphosphatidylglycerol (DOPG) and electrically neutral dioleoylphosphatidylcholine (DOPC). By analyzing this result, the values of Ua of tension-induced rupture of DOPG/DOPC-GUVs were obtained. Ua decreased with an increase in σ, supporting the classical theory of tension-induced pore formation. The analysis of the relationship between Ua and σ using the theory on the electrostatic interaction effects on the tension-induced rupture of GUVs provided the equation of Ua including electrostatic interaction effects, which well fits the experimental data of the tension dependence of Ua. A constant which does not depend on tension, U0, was also found to contribute significantly to Ua. The Arrhenius equations for kp using the equation of Ua and the parameters determined by the above analysis fit well to the experimental data of the tension dependence of kp for DOPG/DOPC-GUVs as well as for DOPC-GUVs. On the basis of these results, we discussed the possible elementary processes underlying the tension-induced rupture of GUVs of lipid membranes. These results indicate that the Arrhenius equation using the experimentally determined Ua is useful in the analysis of tension-induced rupture of GUVs.

  6. Studies on chalcone derivatives: Complex formation, thermal behavior, stability constant and antioxidant activity

    NASA Astrophysics Data System (ADS)

    El-Sayed, Yusif S.; Gaber, M.

    2015-02-01

    The chalcone 3-[4‧-dimethylaminophenyl]-1-(2-pyridyl) prop-2-en-1-one (DMAPP) and 3-(4‧-diethylaminophenyl)-1-(2-pyridinyl) prop-2-en-1-one abbreviated as DEAPP have been synthesized and characterized with IR, 1H NMR, 13C NMR spectroscopic techniques as described previously (El-Daly et al., 2008; Gaber et al., 2009; El-Sayed, 2013). By using UV visible spectroscopy method the mole fraction ratio for copper with DMAPP and DEAPP complexes were determined and it was found to be 1:1. The stability constants of this complex have been determined by Job's method. The stability constant (Kf) of copper with DMAPP and DEAPP complexes in universal buffer pH = 3.2 was determined to be 9.9 × 104 and 5.2 × 104 respectively. The effect of Cu(II) ion on the emission spectrum of the free chalcone is also assigned. Adherence to Beer's law and Ringbom optimum concentration ranges are determined. The thermal decomposition of the metal complexes is studied by TGA technique. The kinetic parameters like activation energy, pre-exponential factor and entropy of activation are estimated. The structure of complexes was energetically optimized through molecular mechanics applying MM+ force field coupled with molecular dynamics simulation. The bond lengths and bond angles have been calculated to confirm the geometry of the ligands and their Cu(II) complexes. The mode of interaction of the chalcone to copper nanoparticles was studied. The apparent association constants of the colloidal copper nanoparticles:chalcone complexes in solution were evaluated using the spectral method and compared with the formation constant of the Cu(II) chalcone complexes. Antioxidant activity of these chalcones was evaluated by using 1,1‧-diphenyl-2-picrylhydrazyl (DPPHrad) radicals scavenging method, which showed that the antioxidant activity of DMAPP has higher value than the DEAPP. Semi-empirical study results showed that DMAPP have higher dipole moment than DEAPP [1].

  7. Effects of Vocabulary Instruction Using Constant Time Delay on Expository Reading of Young Adults with Intellectual Disability

    ERIC Educational Resources Information Center

    Hua, Youjia; Woods-Groves, Suzanne; Kaldenberg, Erica R.; Scheidecker, Bethany J.

    2013-01-01

    We investigated the effectiveness of using constant time delay (CTD) with young adults with intellectual disability on their vocabulary acquisition and retention, as well as expository reading comprehension. Four learners, ages 19 to 21 years, from a postsecondary education program for individuals with disabilities participated in the study.…

  8. Identification of Printed Nonsense Words for an Individual with Autism: A Comparison of Constant Time Delay and Stimulus Fading

    ERIC Educational Resources Information Center

    Redhair, Emily

    2011-01-01

    This study compared a stimulus fading (SF) procedure with a constant time delay (CTD) procedure for identification of consonant-vowel-consonant (CVC) nonsense words for a participant with autism. An alternating treatments design was utilized through a computer-based format. Receptive identification of target words was evaluated using a computer…

  9. Identification of Printed Nonsense Words for an Individual with Autism: A Comparison of Constant Time Delay and Stimulus Fading

    ERIC Educational Resources Information Center

    Redhair, Emily I.; McCoy, Kathleen M.; Zucker, Stanley H.; Mathur, Sarup R.; Caterino, Linda

    2013-01-01

    This study compared a stimulus fading (SF) procedure with a constant time delay (CTD) procedure for identification of consonant-vowel-consonant (CVC) nonsense words for a participant with autism. An alternating treatments design was utilized through a computer-based format. Receptive identification of target words was evaluated using a computer…

  10. Review of Recent Research Using Constant Time Delay to Teach Chained Tasks to Persons with Developmental Disabilities

    ERIC Educational Resources Information Center

    Dogoe, Maud; Banda, Devender R.

    2009-01-01

    We reviewed twelve studies that used the constant time delay (CTD) procedure to teach chained tasks to individuals with developmental disabilities from years 1996-2006. Variables analyzed include types of tasks that have been taught with the procedure, how effective CTD has been in teaching participants, and whether researchers have investigated…

  11. Comparing Simultaneous Prompting and Constant Time Delay to Teach Leisure Skills to Students with Moderate Intellectual Disability

    ERIC Educational Resources Information Center

    Seward, Jannike; Schuster, John W.; Ault, Melinda Jones; Collins, Belva C.; Hall, Meada

    2014-01-01

    We compared the effects of simultaneous prompting and constant time delay in teaching two solitaire card games to five high school students with moderate intellectual disability. An adapted alternating treatments within a multiple probe design was used to evaluate the effectiveness and efficiency of the procedures. Both procedures were effective…

  12. Using Video Prompting and Constant Time Delay to Teach an Internet Search Basic Skill to Students with Intellectual Disabilities

    ERIC Educational Resources Information Center

    Zisimopoulos, Dimitrios; Sigafoos, Jeff; Koutromanos, George

    2011-01-01

    We evaluated a video prompting and a constant time delay procedure for teaching three primary school students with moderate intellectual disabilities to access the Internet and download pictures related to participation in a classroom History project. Video clips were used as an antecedent prompt and as an error correction technique within a…

  13. Teaching Generalized Reading of Product Warning Labels to Young Adults with Autism Using the Constant Time Delay Procedure

    ERIC Educational Resources Information Center

    Dogoe, Maud S.; Banda, Devender R.; Lock, Robin H.; Feinstein, Rita

    2011-01-01

    This study examined the effectiveness of the constant timed delay procedure for teaching two young adults with autism to read, define, and state the contextual meaning of keywords on product warning labels of common household products. Training sessions were conducted in the dyad format using flash cards. Results indicated that both participants…

  14. The Effects of Constant Time Delay and Instructive Feedback on the Acquisition of English and Spanish Sight Words

    ERIC Educational Resources Information Center

    Appelman, Michelle; Vail, Cynthia O.; Lieberman-Betz, Rebecca G.

    2014-01-01

    The authors of this study evaluated the acquisition of instructive feedback information presented to four kindergarten children with mild delays taught in dyads using a constant time delay (CTD) procedure. They also assessed the learning of observational (dyadic partner) information within this instructional arrangement. A multiple probe design…

  15. Effects of Constant Time Delay Procedure on the Halliwick's Method of Swimming Rotation Skills for Children with Autism

    ERIC Educational Resources Information Center

    Yilmaz, Ilker; Konukman, Ferman; Birkan, Binyamin; Ozen, Arzu; Yanardag, Mehmet; Camursoy, Ilhan

    2010-01-01

    Effects of a constant time delay procedure on the Halliwick's method of swimming rotation skills (i.e., vertical and lateral rotation) for children with autism were investigated. A single subject multiple baseline model across behaviors with probe conditions was used. Participants were three boys, 8-9 years old. Data were collected over a 10-week…

  16. Isothermal titration calorimetry determination of individual rate constants of trypsin catalytic activity.

    PubMed

    Aguirre, César; Condado-Morales, Itzel; Olguin, Luis F; Costas, Miguel

    2015-06-15

    Determination of individual rate constants for enzyme-catalyzed reactions is central to the understanding of their mechanism of action and is commonly obtained by stopped-flow kinetic experiments. However, most natural substrates either do not fluoresce/absorb or lack a significant change in their spectra while reacting and, therefore, are frequently chemically modified to render adequate molecules for their spectroscopic detection. Here, isothermal titration calorimetry (ITC) was used to obtain Michaelis-Menten plots for the trypsin-catalyzed hydrolysis of several substrates at different temperatures (278-318K): four spectrophotometrically blind lysine and arginine N-free esters, one N-substituted arginine ester, and one amide. A global fitting of these data provided the individual rate constants and activation energies for the acylation and deacylation reactions, and the ratio of the formation and dissociation rates of the enzyme-substrate complex, leading also to the corresponding free energies of activation. The results indicate that for lysine and arginine N-free esters deacylation is the rate-limiting step, but for the N-substituted ester and the amide acylation is the slowest step. It is shown that ITC is able to produce quality kinetic data and is particularly well suited for those enzymatic reactions that cannot be measured by absorption or fluorescence spectroscopy.

  17. Time evolution of the fine structure constant in a two-field quintessence model

    NASA Astrophysics Data System (ADS)

    Bento, M. C.; Bertolami, O.; Santos, N. M.

    2004-11-01

    We examine the variation of the fine structure constant in the context of a two-field quintessence model. We find that, for solutions that lead to a transient late period of accelerated expansion, it is possible to fit the data arising from quasar spectra and comply with the bounds on the variation of α from the Oklo reactor, meteorite analysis, atomic clock measurements, cosmic microwave background radiation, and big bang nucleosynthesis. That is more difficult if we consider solutions corresponding to a late period of permanent accelerated expansion.

  18. Time-variability of the fine-structure constant expected from the Oklo constraint and the QSO absorption lines

    NASA Astrophysics Data System (ADS)

    Fujii, Yasunori

    2003-10-01

    The data from the QSO absorption lines indicating a nonzero time-variability of the fine-structure constant has been re-analyzed on the basis of a ``damped-oscillator'' fit, as motivated by the same type of behavior of a scalar field, dilaton, which mimics a cosmological constant to understand the accelerating universe. We find nearly as good fit to the latest data as the simple weighted mean. In this way, we offer a way to fit the more stringent result from the Oklo phenomenon, as well.

  19. Removal of visual feedback alters muscle activity and reduces force variability during constant isometric contractions.

    PubMed

    Baweja, Harsimran S; Patel, Bhavini K; Martinkewiz, Julie D; Vu, Julie; Christou, Evangelos A

    2009-07-01

    The purpose of this study was to compare force accuracy, force variability and muscle activity during constant isometric contractions at different force levels with and without visual feedback and at different feedback gains. In experiment 1, subjects were instructed to accurately match the target force at 2, 15, 30, 50, and 70% of their maximal isometric force with abduction of the index finger and maintain their force even in the absence of visual feedback. Each trial lasted 22 s and visual feedback was removed from 8-12 to 16-20 s. Each subject performed 6 trials at each target force, half with visual gain of 51.2 pixels/N and the rest with a visual gain of 12.8 pixels/N. Force error was calculated as the root mean square error of the force trace from the target line. Force variability was quantified as the standard deviation and coefficient of variation (CVF) of the force trace. The EMG activity of the agonist (first dorsal interosseus; FDI) was measured with bipolar surface electrodes placed distal to the innervation zone. Independent of visual gain and force level, subjects exhibited lower force error with the visual feedback condition (2.53 +/- 2.95 vs. 2.71 +/- 2.97 N; P < 0.01); whereas, force variability was lower when visual feedback was removed (CVF: 4.06 +/- 3.11 vs. 4.47 +/- 3.14, P < 0.01). The EMG activity of the FDI muscle was higher during the visual feedback condition and this difference increased especially at higher force levels (70%: 370 +/- 149 vs. 350 +/- 143 microV, P < 0.01). Experiment 2 examined whether the findings of experiment 1 were driven by the higher force levels and proximity in the gain of visual feedback. Subjects performed constant isometric contractions with the abduction of the index finger at an absolute force of 2 N, with two distinct feedback gains of 15 and 3,000 pixels/N. In agreement with the findings of experiment 1, subjects exhibited lower force error in the presence of visual feedback especially when the feedback

  20. Design and use of a constant geometry system to measure activated indium foil in personnel security badges

    SciTech Connect

    Barclay, R.K.

    1984-06-01

    A device for measuring the exposure rate from neutron-activated indium foil, under constant geometry, has been designed, constructed, and tested. The device is intended for use with the Juno ionization chambers, although it adapts to Victoreen CDV-700 and Victoreen 193 G-M instruments. Juno dose-response data for low (53 rad) and high (226 rad) doses were compiled and modeled. This model was compared to that assumed from the indium foil dose-response model in current use; plots of fitted and assumed models are congruent. An analysis of data from both Juno and CDV-700 instruments indicates that the constant geometry device may be used effectively to monitor the decay of In-116m. Tolerance limits for the Juno dose-response curve increase with time after activation, which results in diminished precision of dose estimates made by indium foil measurement. From the data collected in these experiments, the system appears to be most useful if activation is measured within 250 min after exposure. 5 references, 7 figures, 1 table.

  1. A Unified Kinetics and Equilibrium Experiment: Rate Law, Activation Energy, and Equilibrium Constant for the Dissociation of Ferroin

    ERIC Educational Resources Information Center

    Sattar, Simeen

    2011-01-01

    Tris(1,10-phenanthroline)iron(II) is the basis of a suite of four experiments spanning 5 weeks. Students determine the rate law, activation energy, and equilibrium constant for the dissociation of the complex ion in acid solution and base dissociation constant for phenanthroline. The focus on one chemical system simplifies a daunting set of…

  2. Quantum logic gates from time-dependent global magnetic field in a system with constant exchange

    SciTech Connect

    Nenashev, A. V. Dvurechenskii, A. V.; Zinovieva, A. F.; Gornov, A. Yu.; Zarodnyuk, T. S.

    2015-03-21

    We propose a method that implements a universal set of one- and two-quantum-bit gates for quantum computation in a system of coupled electron pairs with constant non-diagonal exchange interaction. In our proposal, suppression of the exchange interaction is performed by the continual repetition of single-spin rotations. A small g-factor difference between the electrons allows for addressing qubits and avoiding strong magnetic field pulses. Numerical experiments were performed to show that, to implement the one- and two-qubit operations, it is sufficient to change the strength of the magnetic field by a few Gauss. This introduces one and then the other electron in a resonance. To determine the evolution of the two-qubit system, we use the algorithms of optimal control theory.

  3. Reduction of the hydraulic retention time at constant high organic loading rate to reach the microbial limits of anaerobic digestion in various reactor systems.

    PubMed

    Ziganshin, Ayrat M; Schmidt, Thomas; Lv, Zuopeng; Liebetrau, Jan; Richnow, Hans Hermann; Kleinsteuber, Sabine; Nikolausz, Marcell

    2016-10-01

    The effects of hydraulic retention time (HRT) reduction at constant high organic loading rate on the activity of hydrogen-producing bacteria and methanogens were investigated in reactors digesting thin stillage. Stable isotope fingerprinting was additionally applied to assess methanogenic pathways. Based on hydA gene transcripts, Clostridiales was the most active hydrogen-producing order in continuous stirred tank reactor (CSTR), fixed-bed reactor (FBR) and anaerobic sequencing batch reactor (ASBR), but shorter HRT stimulated the activity of Spirochaetales. Further decreasing HRT diminished Spirochaetales activity in systems with biomass retention. Based on mcrA gene transcripts, Methanoculleus and Methanosarcina were the predominantly active in CSTR and ASBR, whereas Methanosaeta and Methanospirillum activity was more significant in stably performing FBR. Isotope values indicated the predominance of aceticlastic pathway in FBR. Interestingly, an increased activity of Methanosaeta was observed during shortening HRT in CSTR and ASBR despite high organic acids concentrations, what was supported by stable isotope data.

  4. Reduction of the hydraulic retention time at constant high organic loading rate to reach the microbial limits of anaerobic digestion in various reactor systems.

    PubMed

    Ziganshin, Ayrat M; Schmidt, Thomas; Lv, Zuopeng; Liebetrau, Jan; Richnow, Hans Hermann; Kleinsteuber, Sabine; Nikolausz, Marcell

    2016-10-01

    The effects of hydraulic retention time (HRT) reduction at constant high organic loading rate on the activity of hydrogen-producing bacteria and methanogens were investigated in reactors digesting thin stillage. Stable isotope fingerprinting was additionally applied to assess methanogenic pathways. Based on hydA gene transcripts, Clostridiales was the most active hydrogen-producing order in continuous stirred tank reactor (CSTR), fixed-bed reactor (FBR) and anaerobic sequencing batch reactor (ASBR), but shorter HRT stimulated the activity of Spirochaetales. Further decreasing HRT diminished Spirochaetales activity in systems with biomass retention. Based on mcrA gene transcripts, Methanoculleus and Methanosarcina were the predominantly active in CSTR and ASBR, whereas Methanosaeta and Methanospirillum activity was more significant in stably performing FBR. Isotope values indicated the predominance of aceticlastic pathway in FBR. Interestingly, an increased activity of Methanosaeta was observed during shortening HRT in CSTR and ASBR despite high organic acids concentrations, what was supported by stable isotope data. PMID:26853042

  5. Frequency ratio of two optical clock transitions in 171Yb+ and constraints on the time variation of fundamental constants.

    PubMed

    Godun, R M; Nisbet-Jones, P B R; Jones, J M; King, S A; Johnson, L A M; Margolis, H S; Szymaniec, K; Lea, S N; Bongs, K; Gill, P

    2014-11-21

    Singly ionized ytterbium, with ultranarrow optical clock transitions at 467 and 436 nm, is a convenient system for the realization of optical atomic clocks and tests of present-day variation of fundamental constants. We present the first direct measurement of the frequency ratio of these two clock transitions, without reference to a cesium primary standard, and using the same single ion of 171Yb+. The absolute frequencies of both transitions are also presented, each with a relative standard uncertainty of 6×10(-16). Combining our results with those from other experiments, we report a threefold improvement in the constraint on the time variation of the proton-to-electron mass ratio, μ/μ=0.2(1.1)×10(-16)  yr(-1), along with an improved constraint on time variation of the fine structure constant, α/α=-0.7(2.1)×10(-17)  yr(-1). PMID:25479482

  6. Spatial variability of time-constant slip rates on the San Jacinto fault zone, southern California

    NASA Astrophysics Data System (ADS)

    Blisniuk, K.; Oskin, M. E.; Sharp, W. D.; Meriaux, A. B.; Rockwell, T. K.; Fletcher, K.; Owen, L. A.

    2011-12-01

    In southern California, the San Andreas (SAF) and San Jacinto fault (SJF) zones account for 70-80% of the relative dextral motion between the Pacific and North American plates, with some studies suggesting that the SJF zone may be the dominant structure. However, few slip rate measurements are available for the SJF zone, making it difficult to evaluate the partitioning of deformation across the plate boundary. To more reliably constrain the late Quaternary slip history of the SJF zone, we measured the displacement of well-preserved alluvial fans along the Clark and Coyote Creek fault strands of the SJF zone using field mapping and high-resolution LiDAR topographic data, and dated the fans using U-series on pedogenic carbonate clast-coatings and in situ cosmogenic 10Be. Our results from four sites along the Clark fault strand and two sites along the Coyote Creek fault strand indicate that late Quaternary slip rates have fluctuated along their length but have remained constant since the late Pleistocene. Slip rates along the Clark fault strand over the past 50-30 kyr decrease southward over a distance of ~60 km from ~13 mm/yr at Anza, to 8.9 ± 2.0 mm/yr at Rockhouse Canyon, and 1.5 ± 0.4 mm/yr near the SE end of the Santa Rosa Mountains, probably due to transfer of slip from the Clark fault strand to the Coyote Creek fault strand and nearby zones of distributed deformation. Slip rates of up to ~14 to 18 mm/yr summed across the southern SJF zone suggest that since the latest Pleistocene, the SJF zone may rival the southern SAF zone in accommodating deformation across the Pacific-North America Plate boundary.

  7. Real-time association rate constant measurement using combination tapered fiber-optic biosensor (CTFOB) dip-probes

    PubMed Central

    Simmonds, Boris; Wang, Chun-Wei; Kapoor, Rakesh

    2011-01-01

    This document reports a novel method of measuring association rate constant (ka) for antibody-antigen interaction using evanescent wave-based combination tapered fiber-optic biosensor (CTFOB) dip-probes. The method was demonstrated by measuring association rate constant for bovine serum albumin (BSA) and anti-BSA antibody interaction. “Direct method” was used for detection; goat anti-BSA “capture” antibodies were immobilized on the probe surfaces while the antigen (BSA) was directly labeled with Alexa 488 dye. The probes were subsequently submerged in 3 nM Labeled BSA in egg albumin (1 mg/ml). The fluorescence signal recorded was proportional to BSA anti-BSA conjugates and continuous signal was acquired suing a fiber optic spectrometer (Ocean Optics, Inc.). A 476 nm diode laser was use as an excitation source. Association constant was estimated from a plot of signal as a function of time. Measured association rate constant ka for the binding of BSA with anti-BSA at room temperature is (8.33 ± 0.01) ×104 M−1 s−1. PMID:21643496

  8. Off-line correction for excessive constant-fraction-discriminator walk in neutron time-of-flight experiments

    SciTech Connect

    Heilbronn, Lawrence; Iwata, Yoshiyuki; Iwase, H.

    2003-10-15

    A method for reducing excessive constant-fraction-discriminator walk that utilizes experimental data in the off-line analysis stage is introduced. Excessive walk is defined here as any walk that leads to an overall timing resolution that is much greater than the intrinsic timing resolution of the detection system. The method is able to reduce the contribution to the overall timing resolution from the walk that is equal to or less than the intrinsic timing resolution of the detectors. Although the method is explained in the context of a neutron time-of-flight experiment, it is applicable to any data set that satisfies two conditions. (1) A measure of the signal amplitude for each event must be recorded on an event-by-event basis; and (2) There must be a distinguishable class of events present where the timing information is known a priori.

  9. Gravitational Lens Time Delays: A Statistical Assessmentof Lens Model Dependences and Implications for the Global Hubble Constant

    SciTech Connect

    Oguri, Masamune; /KIPAC, Menlo Park

    2006-09-29

    Time delays between lensed multiple images have been known to provide an interesting probe of the Hubble constant, but such application is often limited by degeneracies with the shape of lens potentials. We propose a new statistical approach to examine the dependence of time delays on the complexity of lens potentials, such as higher-order perturbations, non-isothermality, and substructures. Specifically, we introduce a reduced time delay of the dimensionless form, and explore its behavior analytically and numerically as a function of the image configuration that is characterized by the asymmetry and opening angle of the image pair. In particular we derive a realistic conditional probability distribution for a given image configuration from Monte-Carlo simulations. We find that the probability distribution is sensitive to the image configuration such that more symmetric and/or smaller opening angle image pairs are more easily affected by perturbations on the primary lens potential. On average time delays of double lenses are less scattered than those of quadruple lenses. Furthermore, the realistic conditional distribution allows a new statistical method to constrain the Hubble constant from observed time delays. We find that 15 published time delay quasars constrain the Hubble constant to be H{sub 0} = 70 {+-} 3km s{sup -1} Mpc{sup -1}. While systematic errors coming from the heterogeneous nature of the quasar sample and the uncertainty of the input distribution of lens potentials should be considered, reasonable agreement with other estimates indicates the usefulness of our new approach as a cosmological and astrophysical probe, particularly in the era of large-scale synoptic surveys.

  10. An Efficient Format for Nearly Constant-Time Access to Arbitrary Time Intervals in Large Trace Files

    DOE PAGES

    Chan, Anthony; Gropp, William; Lusk, Ewing

    2008-01-01

    A powerful method to aid in understanding the performance of parallel applications uses log or trace files containing time-stamped events and states (pairs of events). These trace files can be very large, often hundreds or even thousands of megabytes. Because of the cost of accessing and displaying such files, other methods are often used that reduce the size of the tracefiles at the cost of sacrificing detail or other information. This paper describes a hierarchical trace file format that provides for display of an arbitrary time window in a time independent of the total size of the file andmore » roughly proportional to the number of events within the time window. This format eliminates the need to sacrifice data to achieve a smaller trace file size (since storage is inexpensive, it is necessary only to make efficient use of bandwidth to that storage). The format can be used to organize a trace file or to create a separate file of annotations that may be used with conventional trace files. We present an analysis of the time to access all of the events relevant to an interval of time and we describe experiments demonstrating the performance of this file format.« less

  11. Estimation of the path-averaged atmospheric refractive index structure constant from time-lapse imagery

    NASA Astrophysics Data System (ADS)

    Basu, Santasri; McCrae, Jack E.; Fiorino, Steven T.

    2015-05-01

    A time-lapse imaging experiment was conducted to monitor the effects of the atmosphere over some period of time. A tripod-mounted digital camera captured images of a distant building every minute. Correlation techniques were used to calculate the position shifts between the images. Two factors causing shifts between the images are: atmospheric turbulence, causing the images to move randomly and quickly, plus changes in the average refractive index gradient along the path which cause the images to move vertically, more slowly and perhaps in noticeable correlation with solar heating and other weather conditions. A technique for estimating the path-averaged C 2n from the random component of the image motion is presented here. The technique uses a derived set of weighting functions that depend on the size of the imaging aperture and the patch size in the image whose motion is being tracked. Since this technique is phase based, it can be applied to strong turbulence paths where traditional irradiance based techniques suffer from saturation effects.

  12. Theoretical determination of chemical rate constants using novel time-dependent methods

    NASA Technical Reports Server (NTRS)

    Dateo, Christopher E.

    1994-01-01

    The work completed within the grant period 10/1/91 through 12/31/93 falls primarily in the area of reaction dynamics using both quantum and classical mechanical methodologies. Essentially four projects have been completed and have been or are in preparation of being published. The majority of time was spent in the determination of reaction rate coefficients in the area of hydrocarbon fuel combustion reactions which are relevant to NASA's High Speed Research Program (HSRP). These reaction coefficients are important in the design of novel jet engines with low NOx emissions, which through a series of catalytic reactions contribute to the deterioration of the earth's ozone layer. A second area of research studied concerned the control of chemical reactivity using ultrashort (femtosecond) laser pulses. Recent advances in pulsed-laser technologies have opened up a vast new field to be investigated both experimentally and theoretically. The photodissociation of molecules adsorbed on surfaces using novel time-independent quantum mechanical methods was a third project. And finally, using state-of-the-art, high level ab initio electronic structure methods in conjunction with accurate quantum dynamical methods, the rovibrational energy levels of a triatomic molecule with two nonhydrogen atoms (HCN) were calculated to unprecedented levels of agreement between theory and experiment.

  13. Light deflection, lensing, and time delays from gravitational potentials and Fermat's principle in the presence of a cosmological constant

    SciTech Connect

    Ishak, Mustapha

    2008-11-15

    The contributions of the cosmological constant to the deflection angle and the time delays are derived from the integration of the gravitational potential as well as from Fermat's principle. The findings are in agreement with recent results using exact solutions to Einstein's equations and reproduce precisely the new {lambda} term in the bending angle and the lens equation. The consequences on time-delay expressions are explored. While it is known that {lambda} contributes to the gravitational time delay, it is shown here that a new {lambda} term appears in the geometrical time delay as well. Although these newly derived terms are perhaps small for current observations, they do not cancel out as previously claimed. Moreover, as shown before, at galaxy cluster scale, the {lambda} contribution can be larger than the second-order term in the Einstein deflection angle for several cluster lens systems.

  14. The application of constant recycle solids concentration in activated sludge process.

    PubMed

    Bonotan-Dura, F M; Yang, P Y

    1976-02-01

    The applicability of the model derived by Ramanathan and Gaudy (Biotechnol. Bioeng., 11, 207, (1969)) for completely mixed activated sludge treatment holding the recycle solids concentration as a system constant was investigated using an actual industrial organic wastewater. Short-term experiments were conducted at various dilution rates (1/8, 1/6, 1/4, 1/2, 1/1.5 hr-1) for two recycle solids concentration values (5000 and 7000 mg/liter). The influent substrate concentration was maintained at 1000 mg/liter COD and the hydraulic recycle ratio- alpha, was kept at 0.3. It was found that for bottling plant (Pepsi Cola) wastewaters, a steady state with respect to reactor biological solids and effluent COD, at different dilution rates, could be attained, lending experimental evidence to the assumption that a steady state could be reached in developing the model and also affecting the applicability of the model in industrial organic wastewater. The reactor biological solids and effluent COD calculated from the model closely agreed with the observed values at dilution rates lower than 0.5 hr-1. Operation at dilution rates higher than 0.5 hr-1 will washout the biological solids from the reactor and the recycle substrate concentration will be apparent if the concentration of XR were not increased.

  15. Classification of muscle activity based on effort level during constant pace running.

    PubMed

    Stirling, Lisa M; von Tscharner, Vinzenz; Kugler, Patrick F; Nigg, Benno M

    2011-08-01

    During running, psychologic and physiologic changes are manifested in the perception of effort, muscle properties and movement strategies. The latter two aspects are expressed as changes in electromyographic (EMG) activity. This paper tests the hypothesis that the EMG signals change in a systematic way during a run and that these changes are related to the effort level of the runner. Fifteen female recreational runners performed 1-h treadmill runs at a constant speed (95% of speed at ventilatory threshold). EMG signals were recorded from four muscles (tibialis anterior, gastrocnemius medialis, vastus lateralis, and semitendinosus). The wavelet transformed EMG data were used to discriminate between different effort phases of running using a support vector machine (SVM) approach. The effect of the penalty parameter, C, and cross validation folds, n, used were evaluated and found to have little influence on the outcome. Recognition rates of >80% were achieved for all C and n values across all muscles. Average recognition rates were: TA - 89.2, GM - 88.3%, VL - 84.6% and ST - 94.0%. These results suggest that selected lower extremity EMG signals using wavelet-based methods contained highly systematic differences that could be used by the SVM to discriminate between the low- and high-effort stages of prolonged running.

  16. Lab-scale experimental strategy for determining micropollutant partition coefficient and biodegradation constants in activated sludge.

    PubMed

    Pomiès, M; Choubert, J M; Wisniewski, C; Miège, C; Budzinski, H; Coquery, M

    2015-03-01

    The nitrifying/denitrifying activated sludge process removes several micropollutants from wastewater by sorption onto sludge and/or biodegradation. The objective of this paper is to propose and evaluate a lab-scale experimental strategy for the determination of partition coefficient and biodegradation constant for micropollutant with an objective of modelling their removal. Four pharmaceutical compounds (ibuprofen, atenolol, diclofenac and fluoxetine) covering a wide hydrophobicity range (log Kow from 0.16 to 4.51) were chosen. Dissolved and particulate concentrations were monitored for 4 days, inside two reactors working under aerobic and anoxic conditions, and under different substrate feed conditions (biodegradable carbon and nitrogen). We determined the mechanisms responsible for the removal of the target compounds: (i) ibuprofen was biodegraded, mainly under aerobic conditions by cometabolism with biodegradable carbon, whereas anoxic conditions suppressed biodegradation; (ii) atenolol was biodegraded under both aerobic and anoxic conditions (with a higher biodegradation rate under aerobic conditions), and cometabolism with biodegradable carbon was the main mechanism; (iii) diclofenac and fluoxetine were removed by sorption only. Finally, the abilities of our strategy were evaluated by testing the suitability of the parameters for simulating effluent concentrations and removal efficiency at a full-scale plant. PMID:25300180

  17. Classification of muscle activity based on effort level during constant pace running.

    PubMed

    Stirling, Lisa M; von Tscharner, Vinzenz; Kugler, Patrick F; Nigg, Benno M

    2011-08-01

    During running, psychologic and physiologic changes are manifested in the perception of effort, muscle properties and movement strategies. The latter two aspects are expressed as changes in electromyographic (EMG) activity. This paper tests the hypothesis that the EMG signals change in a systematic way during a run and that these changes are related to the effort level of the runner. Fifteen female recreational runners performed 1-h treadmill runs at a constant speed (95% of speed at ventilatory threshold). EMG signals were recorded from four muscles (tibialis anterior, gastrocnemius medialis, vastus lateralis, and semitendinosus). The wavelet transformed EMG data were used to discriminate between different effort phases of running using a support vector machine (SVM) approach. The effect of the penalty parameter, C, and cross validation folds, n, used were evaluated and found to have little influence on the outcome. Recognition rates of >80% were achieved for all C and n values across all muscles. Average recognition rates were: TA - 89.2, GM - 88.3%, VL - 84.6% and ST - 94.0%. These results suggest that selected lower extremity EMG signals using wavelet-based methods contained highly systematic differences that could be used by the SVM to discriminate between the low- and high-effort stages of prolonged running. PMID:21459608

  18. The application of constant recycle solids concentration in activated sludge process.

    PubMed

    Bonotan-Dura, F M; Yang, P Y

    1976-02-01

    The applicability of the model derived by Ramanathan and Gaudy (Biotechnol. Bioeng., 11, 207, (1969)) for completely mixed activated sludge treatment holding the recycle solids concentration as a system constant was investigated using an actual industrial organic wastewater. Short-term experiments were conducted at various dilution rates (1/8, 1/6, 1/4, 1/2, 1/1.5 hr-1) for two recycle solids concentration values (5000 and 7000 mg/liter). The influent substrate concentration was maintained at 1000 mg/liter COD and the hydraulic recycle ratio- alpha, was kept at 0.3. It was found that for bottling plant (Pepsi Cola) wastewaters, a steady state with respect to reactor biological solids and effluent COD, at different dilution rates, could be attained, lending experimental evidence to the assumption that a steady state could be reached in developing the model and also affecting the applicability of the model in industrial organic wastewater. The reactor biological solids and effluent COD calculated from the model closely agreed with the observed values at dilution rates lower than 0.5 hr-1. Operation at dilution rates higher than 0.5 hr-1 will washout the biological solids from the reactor and the recycle substrate concentration will be apparent if the concentration of XR were not increased. PMID:1252608

  19. Chemical to electrical transduction mechanisms from single metal oxide nanowire measurements: response time constant analysis

    NASA Astrophysics Data System (ADS)

    Morante, J. R.

    2013-11-01

    Insight into chemical to electrical transduction mechanisms taking place at the surface of a single metal oxide nanowire is reported due to its outstanding importance for determining the characteristics of resistive solid state gas sensors. The surface chemical reaction kinetics is discussed considering competitiveness phenomena among different active sites and gas species on the nanowire taken as a metal oxide monocrystal at the nanoscale level. Experimental results for different representative gas molecules are shown to determine and understand sensor selectivity. The reported gas species are carbon monoxide and water vapour as general reference molecules, and ethanol and ammonia species as special references for gas-solid interactions, respectively, on acid and basic sites. Kinetic properties are proposed as particular signatures for each of the possible surface chemical reactions, allowing their identification and distinction. Likewise, features such as thermal inertia limitation and effects of the molecular and monoatomic absorbed oxygen are also estimated considering operation working modes based on nanowire self-heating. Furthermore, the applicability of a surface electrical field on a one-dimensional metal oxide nanostructure to enhance the surface ionization of the absorbed molecules is also reviewed as a new type of metal oxide based nanosensor for achieving improved selectivity.

  20. Spectral editing of weakly coupled spins using variable flip angles in PRESS constant echo time difference spectroscopy: Application to GABA

    NASA Astrophysics Data System (ADS)

    Snyder, Jeff; Hanstock, Chris C.; Wilman, Alan H.

    2009-10-01

    A general in vivo magnetic resonance spectroscopy editing technique is presented to detect weakly coupled spin systems through subtraction, while preserving singlets through addition, and is applied to the specific brain metabolite γ-aminobutyric acid (GABA) at 4.7 T. The new method uses double spin echo localization (PRESS) and is based on a constant echo time difference spectroscopy approach employing subtraction of two asymmetric echo timings, which is normally only applicable to strongly coupled spin systems. By utilizing flip angle reduction of one of the two refocusing pulses in the PRESS sequence, we demonstrate that this difference method may be extended to weakly coupled systems, thereby providing a very simple yet effective editing process. The difference method is first illustrated analytically using a simple two spin weakly coupled spin system. The technique was then demonstrated for the 3.01 ppm resonance of GABA, which is obscured by the strong singlet peak of creatine in vivo. Full numerical simulations, as well as phantom and in vivo experiments were performed. The difference method used two asymmetric PRESS timings with a constant total echo time of 131 ms and a reduced 120° final pulse, providing 25% GABA yield upon subtraction compared to two short echo standard PRESS experiments. Phantom and in vivo results from human brain demonstrate efficacy of this method in agreement with numerical simulations.

  1. Spatially resolved measurements of mean spin-spin relaxation time constants.

    PubMed

    Nechifor, Ruben Emanuel; Romanenko, Konstantin; Marica, Florea; Balcom, Bruce J

    2014-02-01

    Magnetic Resonance measurements of the T2 distribution have become very common and they are a powerful way to probe microporous fluid bearing solids. While the structure of the T2 distribution, and changes in the structure, are often very informative, it is common to reduce the T2 distribution to a mean numeric quantity in order to provide a quantitative interpretation of the distribution. Magnetic Resonance Imaging measurements of the T2 distribution have recently been introduced, but they are time consuming, especially for 2 and 3 spatial dimensions. In this paper we explore a direct MRI measurement of the arithmetic mean of 1/T2, characterizing the distribution by using the initial slope of the spatially resolved T2 decay in a CPMG prepared Centric Scan SPRITE experiment. The methodology is explored with a test phantom sample and realistic petroleum reservoir core plug samples. The arithmetic mean of 1/T2 is related to the harmonic mean of T2. The mean obtained from the early decay is explored through measurements of uniform saturated core plug samples and by comparison to other means determined from the complete T2 distribution. Complementary data were obtained using SE-SPI T2 distribution MRI measurements. The utility of the arithmetic mean 1/T2 is explored through measurements of centrifuged core plug samples where the T2 distribution varies spatially. The harmonic mean T2 obtained from the early decay was employed to estimate the irreducible water saturation for core plug samples. PMID:24361482

  2. Spatially resolved measurements of mean spin-spin relaxation time constants

    NASA Astrophysics Data System (ADS)

    Nechifor, Ruben Emanuel; Romanenko, Konstantin; Marica, Florea; Balcom, Bruce J.

    2014-02-01

    Magnetic Resonance measurements of the T2 distribution have become very common and they are a powerful way to probe microporous fluid bearing solids. While the structure of the T2 distribution, and changes in the structure, are often very informative, it is common to reduce the T2 distribution to a mean numeric quantity in order to provide a quantitative interpretation of the distribution. Magnetic Resonance Imaging measurements of the T2 distribution have recently been introduced, but they are time consuming, especially for 2 and 3 spatial dimensions. In this paper we explore a direct MRI measurement of the arithmetic mean of 1/T2, characterizing the distribution by using the initial slope of the spatially resolved T2 decay in a CPMG prepared Centric Scan SPRITE experiment. The methodology is explored with a test phantom sample and realistic petroleum reservoir core plug samples. The arithmetic mean of 1/T2 is related to the harmonic mean of T2. The mean obtained from the early decay is explored through measurements of uniform saturated core plug samples and by comparison to other means determined from the complete T2 distribution. Complementary data were obtained using SE-SPI T2 distribution MRI measurements. The utility of the arithmetic mean 1/T2 is explored through measurements of centrifuged core plug samples where the T2 distribution varies spatially. The harmonic mean T2 obtained from the early decay was employed to estimate the irreducible water saturation for core plug samples.

  3. Change in fibrinolytic activity under the influence of a constant magnetic field. [blood coagulation normilization in heart patients

    NASA Technical Reports Server (NTRS)

    Yepishina, S. G.

    1974-01-01

    The fibrinolytic activity of plasma changes under the influence of a constant magnetic field (CMF) with a strength of 250 or 2500 oersteds. CMF shows a tendency toward normalization of fibrinolytic processes in the presence of pathological disturbances in fibrinolysis activation.

  4. Initial Sensorimotor and Cardiovascular Data Acquired from Soyuz Landings: Establishing a Functional Performance Recovery Time Constant

    NASA Technical Reports Server (NTRS)

    Reschke, M. F.; Kozlovskaya, I. B.; Kofman, I. S.; Tomilovskaya, E. S.; Cerisano, J. M.; Bloomberg, J. J.; Stenger, M. B.; Platts, S. H.; Rukavishnikov, I. V.; Fomina, E. V.; Lee, S. M. C.; Wood, S. J.; Mulavara, A. P.; Feiveson, A. H.; Fisher, E. A.

    2015-01-01

    INTRODUCTION Testing of crew responses following long-duration flights has not been previously possible until a minimum of more than 24 hours after landing. As a result, it has not been possible to determine the trend of the early recovery process, nor has it been possible to accurately assess the full impact of the decrements associated with long-duration flight. To overcome these limitations, both the Russian and U.S. programs have implemented joint testing at the Soyuz landing site. This International Space Station research effort has been identified as the functional Field Test, and represents data collect on NASA, Russian, European Space Agency, and Japanese Aerospace Exploration Agency crews. RESEARCH The primary goal of this research is to determine functional abilities associated with long-duration space flight crews beginning as soon after landing as possible on the day of landing (typically within 1 to 1.5 hours). This goal has both sensorimotor and cardiovascular elements. To date, a total of 15 subjects have participated in a 'pilot' version of the full 'field test'. The full version of the 'field test' will assess functional sensorimotor measurements included hand/eye coordination, standing from a seated position (sit-to-stand), walking normally without falling, measurement of dynamic visual acuity, discriminating different forces generated with the hands (both strength and ability to judge just noticeable differences of force), standing from a prone position, coordinated walking involving tandem heel-to-toe placement (tested with eyes both closed and open), walking normally while avoiding obstacles of differing heights, and determining postural ataxia while standing (measurement of quiet stance). Sensorimotor performance has been obtained using video records, and data from body worn inertial sensors. The cardiovascular portion of the investigation has measured blood pressure and heart rate during a timed stand test in conjunction with postural ataxia

  5. Simple analytical forms of the perpendicular diffusion coefficient for two-component turbulence. II. Dynamical turbulence with constant correlation time

    SciTech Connect

    Shalchi, A.

    2014-01-10

    We explore perpendicular diffusion based on the unified nonlinear transport theory. In Paper I, we focused on magnetostatic turbulence, whereas in the present article we include dynamical turbulence effects. For simplicity, we assume a constant correlation time. We show that there is now a nonvanishing contribution of the slab modes. We explore the parameter regimes in which the turbulence dynamics becomes important for perpendicular diffusion. Analytical forms for the perpendicular diffusion coefficient are derived, which can be implemented easily in solar modulation or shock acceleration codes.

  6. Resimulation of noise: a precision estimator for least square error curve-fitting tested for axial strain time constant imaging.

    PubMed

    Nair, S P; Righetti, R

    2015-05-01

    Recent elastography techniques focus on imaging information on properties of materials which can be modeled as viscoelastic or poroelastic. These techniques often require the fitting of temporal strain data, acquired from either a creep or stress-relaxation experiment to a mathematical model using least square error (LSE) parameter estimation. It is known that the strain versus time relationships for tissues undergoing creep compression have a non-linear relationship. In non-linear cases, devising a measure of estimate reliability can be challenging. In this article, we have developed and tested a method to provide non linear LSE parameter estimate reliability: which we called Resimulation of Noise (RoN). RoN provides a measure of reliability by estimating the spread of parameter estimates from a single experiment realization. We have tested RoN specifically for the case of axial strain time constant parameter estimation in poroelastic media. Our tests show that the RoN estimated precision has a linear relationship to the actual precision of the LSE estimator. We have also compared results from the RoN derived measure of reliability against a commonly used reliability measure: the correlation coefficient (CorrCoeff). Our results show that CorrCoeff is a poor measure of estimate reliability for non-linear LSE parameter estimation. While the RoN is specifically tested only for axial strain time constant imaging, a general algorithm is provided for use in all LSE parameter estimation.

  7. Design and simulation of the AC-coupled burst-mode receiver with the small time constant

    NASA Astrophysics Data System (ADS)

    Huang, Qiuyuan; Liu, Luling; Li, Senmao; Sun, Leijun

    2008-12-01

    Due to the Multipoint-to-Point nature of the uplink, the upstream data transmission in a GPON system is burst-mode, and both the guard time and preamble time are much shorter(32 bits and 44 bits respectively).This burst-mode nature of the GPON uplink brings many challenges for the design of the burst-mode receiver. This paper presents an improved design of the main amplifier which is fit for the AC-coupled burst-mode optical receiver with short time constant. Simulation analysis of this scheme at the aspect of the pattern dependent jitter and the data pattern jitter is also presented. Finally, simulation results are provided to show the feasibility of the scheme.

  8. Time to pay attention: attentional performance time-stamped prefrontal cholinergic activation, diurnality and performance

    PubMed Central

    Paolone, Giovanna; Lee, Theresa M.; Sarter, Martin

    2012-01-01

    Although the impairments in cognitive performance that result from shifting or disrupting daily rhythms have been demonstrated, the neuronal mechanisms that optimize fixed time daily performance are poorly understood. We previously demonstrated that daily practice of a sustained attention task (SAT) evokes a diurnal activity pattern in rats. Here we report that SAT practice at a fixed time produced practice time-stamped increases in prefrontal cholinergic neurotransmission that persisted after SAT practice was terminated and in a different environment. SAT time-stamped cholinergic activation occurred irrespective of whether the SAT was practiced during the light or dark phase or in constant light conditions. In contrast, prior daily practice of an operant schedule of reinforcement, albeit generating more rewards and lever presses per session than the SAT, neither activated the cholinergic system nor affected the animals' nocturnal activity pattern. Likewise, food-restricted animals exhibited strong food anticipatory activity (FAA) and attenuated activity during the dark period but FAA was not associated with increases in prefrontal cholinergic activity. Removal of cholinergic neurons impaired SAT performance and facilitated the reemergence of nocturnality. Shifting SAT practice away from a fixed time resulted in significantly lower performance. In conclusion, these experiments demonstrated that fixed time, daily practice of a task assessing attention generates a precisely practice time-stamped activation of the cortical cholinergic input system. Time-stamped cholinergic activation benefits fixed time performance and, if practiced during the light phase, contributes to a diurnal activity pattern. PMID:22933795

  9. A statistical evaluation of effective time constants of random telegraph noise with various operation timings of in-pixel source follower transistors

    NASA Astrophysics Data System (ADS)

    Yonezawa, A.; Kuroda, R.; Teramoto, A.; Obara, T.; Sugawa, S.

    2014-03-01

    We evaluated effective time constants of random telegraph noise (RTN) with various operation timings of in-pixel source follower transistors statistically, and discuss the dependency of RTN time constants on the duty ratio (on/off ratio) of MOSFET which is controlled by the gate to source voltage (VGS). Under a general readout operation of CMOS image sensor (CIS), the row selected pixel-source followers (SFs) turn on and not selected pixel-SFs operate at different bias conditions depending on the select switch position; when select switch locate in between the SF driver and column output line, SF drivers nearly turn off. The duty ratio and cyclic period of selected time of SF driver depends on the operation timing determined by the column read out sequence. By changing the duty ratio from 1 to 7.6 x 10-3, time constant ratio of RTN (time to capture <τc<)/(time to emission <τe<) of a part of MOSFETs increased while RTN amplitudes were almost the same regardless of the duty ratio. In these MOSFETs, <τc< increased and the majority of <τe< decreased and the minority of <τe< increased by decreasing the duty ratio. The same tendencies of behaviors of <τc< and <τe< were obtained when VGS was decreased. This indicates that the effective <τc< and <τe< converge to those under off state as duty ratio decreases. These results are important for the noise reduction, detection and analysis of in pixel-SF with RTN.

  10. Rate constant of exciton quenching of Ir(ppy)3 with hole measured by time-resolved luminescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Oyama, Shiho; Sakai, Heisuke; Murata, Hideyuki

    2016-03-01

    We observed the quenching of tris(2-phenylpyridinato)iridium(III) [Ir(ppy)3] excitons by polarons (holes or electrons) by time-resolved photoluminescence (PL) spectroscopy to clarify the dynamics of the triplet-polaron quenching of excitons. We employed a hole-only device (HOD) and an electron-only device (EOD), where the emitting layer consists of Ir(ppy)3 doped in 4,4‧-bis(carbazol-9-yl)biphenyl. Time-resolved PL spectroscopy of the EOD and HOD were measured under a constant current density. The results showed that the excitons of Ir(ppy)3 were significantly quenched only by holes. The PL decay curves of HOD were well fitted by the biexponential function, where lifetimes (τ1 and τ2) remain unchanged but the coefficient of each exponential term depends on hole current density. From the results, we proposed a model of exciton quenching where the exciton-hole quenching area expands with increasing hole current density. On the basis of the model, the triplet-polaron quenching rate constant Kq was determined.

  11. Analysis of position error by time constant in read-out resistive network for gamma-ray imaging detection system

    NASA Astrophysics Data System (ADS)

    Jeon, Su-Jin; Park, Chang-In; Son, Byung-Hee; Jung, Mi; Jang, Teak-Jin; Lee, Chun-Sik; Choi, Young-Wan

    2016-03-01

    Position-sensitive photomultiplier tubes (PSPMTs) in array are used as gamma ray position detector. Each PMT converts the light of wide spectrum range (100 nm ~ 2500 nm) to electrical signal with amplification. Because detection system size is determined by the number of output channels in the PSPMTs, resistive network has been used for reducing the number of output channels. The photo-generated current is distributed to the four output current pulses according to a ratio by resistance values of resistive network. The detected positions are estimated by the peak value of the distributed current pulses. However, due to parasitic capacitance of PSPMTs in parallel with resistor in the resistive network, the time constants should be considered. When the duration of current pulse is not long enough, peak value of distributed pulses is reduced and detected position error is increased. In this paper, we analyzed the detected position error in the resistive network and variation of time constant according to the input position of the PSPMTs.

  12. Comparing Teacher-Directed and Computer-Assisted Constant Time Delay for Teaching Functional Sight Words to Students with Moderate Intellectual Disability

    ERIC Educational Resources Information Center

    Coleman, Mari Beth; Hurley, Kevin J.; Cihak, David F.

    2012-01-01

    The purpose of this study was to compare the effectiveness and efficiency of teacher-directed and computer-assisted constant time delay strategies for teaching three students with moderate intellectual disability to read functional sight words. Target words were those found in recipes and were taught via teacher-delivered constant time delay or…

  13. Comparison of Constant Time Delay and the System of Least Prompts in Teaching Sight Word Reading to Students with Moderate Retardation.

    ERIC Educational Resources Information Center

    Gast, David L.; And Others

    1988-01-01

    Four moderately mentally retarded students, aged 8-13, were taught to read food words found in grocery stores, using constant time delay or system of least prompts procedures. Both strategies produced criterion-level performance in training and other settings, but the constant time delay procedure was more efficient. (Author/JDD)

  14. The Leisure-Time Activity of Citizens

    ERIC Educational Resources Information Center

    Sedova, N. N.

    2011-01-01

    Survey data show that Russians relegate free time and leisure activity to secondary status compared to work, and free time faces the threat of becoming devalued and losing its importance as a life value. At the same time, in the structure of Russians' leisure activities there is an ongoing tendency for leisure to become simpler, for active types…

  15. Temperature dependence of CsI(Tl) gamma-ray scintillation decay time constants and emission spectrum

    NASA Astrophysics Data System (ADS)

    Valentine, John; Moses, William W.; Derenzo, Stephen E.; Wehe, David K.; Knoll, Glenn F.

    1992-12-01

    The gamma-ray excited, temperature dependent scintillation characteristics of CsI(Tl) are reported over the temperature range of -100 to +50 degree(s)C. The modified Bollinger-Thomas and shaped square wave methods were used to measure the rise and decay times. The emission spectra were measured using a monochromator and corrected for monochromator and photocathode spectral efficiency. The shaped square wave method was also used to determine the scintillation yield as was a current mode method. The thermoluminescence emissions of CsI(Tl) were measured using the same current mode method. At room temperature, CsI(Tl) was found to have two primary decay components with decay time constants of (tau) (subscript 1) equals 679 +/- 10 ns (63.7%) and (tau) (subscript 2) equals 3.34 +/- 0.14 microsecond(s) (36.1%) and to have emission bands at about 400 and 560 nm. The (tau) (subscript 1) luminescent state was observed to be populated by an exponential process with a resulting rise time constant of 19.6 +/- 1.9 ns at room temperature. An ultra-fast decay component with a < 0.5 ns decay time was found to emit about 0.2% (about 100 photons/MeV) of the total scintillation light. At -100 degree(s)C (tau) (subscript 2) was too long to be resolved and (tau) (subscript 1) was determined to be 3.52 +/- 0.39 microsecond(s) , while the 400 nm emission band was not observed. At +50 degree(s)C the decay constants were found to be 628 ns (70%) and 2.63 microsecond(s) (30%) and both emission bands are present. Four different commercially available CsI(Tl) crystals were used. Minimal variations in the measured scintillation characteristics were observed among these four crystals. Thermoluminescence emissions were observed to have peak yields at -90, -65, -40, +20, and possibly -55 degree(s)C. The relative magnitudes and number of thermoluminescence peaks were found to vary from crystal to crystal.

  16. Cobalt, titanium and PMMA bone cement debris influence on mouse osteoblast cell elasticity, spring constant and calcium production activity

    PubMed Central

    Preedy, Emily Callard; Perni, Stefano

    2015-01-01

    Periprosthetic osteolysis and implant loosening are the outcomes of wear debris generation in total joint replacements. Wear debris formed from the implanted materials consisting of metals, polymers, ceramic and bone cement initiate the immune system response. Often osteoblasts, the principal cell type in bone tissue adjacent to the prostheses, are directly impacted. In this study, the influence of cobalt, titanium and PMMA bone cement particles of different sizes, charges and compositions on mouse osteoblast adhesion, nanomechanics (elasticity and spring constant) and metabolic activity were investigated. These studies were accompanied by osteoblast mineralisation experiments and cell uptake after exposure to particles at defined time points. Our results demonstrate that alteration of the nanomechanical properties are mainly dependent on the metal type rather than nanoparticles size and concentration. Moreover, despite uptake increasing over exposure time, the cell characteristics exhibit changes predominately after the first 24 hours, highlighting that the cell responses to nanoparticle exposure are not cumulative. Understanding these processes is critical to expanding our knowledge of implant loosening and elucidating the nature of prosthetic joint failure. PMID:27019701

  17. Lens galaxies in the Illustris simulation: power-law models and the bias of the Hubble constant from time delays

    NASA Astrophysics Data System (ADS)

    Xu, Dandan; Sluse, Dominique; Schneider, Peter; Springel, Volker; Vogelsberger, Mark; Nelson, Dylan; Hernquist, Lars

    2016-02-01

    A power-law density model, i.e. ρ (r) ∝ r^{-γ ^' }}, has been commonly employed in strong gravitational lensing studies, including the so-called time-delay technique used to infer the Hubble constant H0. However, since the radial scale at which strong lensing features are formed corresponds to the transition from the dominance of baryonic matter to dark matter, there is no known reason why galaxies should follow a power law in density. The assumption of a power law artificially breaks the mass-sheet degeneracy, a well-known invariance transformation in gravitational lensing which affects the product of Hubble constant and time delay and can therefore cause a bias in the determination of H0 from the time-delay technique. In this paper, we use the Illustris hydrodynamical simulations to estimate the amplitude of this bias, and to understand how it is related to observational properties of galaxies. Investigating a large sample of Illustris galaxies that have velocity dispersion σSIE ≥ 160 km s-1 at redshifts below z = 1, we find that the bias on H0 introduced by the power-law assumption can reach 20-50 per cent, with a scatter of 10-30 per cent (rms). However, we find that by selecting galaxies with an inferred power-law model slope close to isothermal, it is possible to reduce the bias on H0 to ≲ 5 per cent and the scatter to ≲ 10 per cent. This could potentially be used to form less biased statistical samples for H0 measurements in the upcoming large survey era.

  18. Linear free energy relationships between aqueous phase hydroxyl radical reaction rate constants and free energy of activation.

    PubMed

    Minakata, Daisuke; Crittenden, John

    2011-04-15

    The hydroxyl radical (HO(•)) is a strong oxidant that reacts with electron-rich sites on organic compounds and initiates complex radical chain reactions in aqueous phase advanced oxidation processes (AOPs). Computer based kinetic modeling requires a reaction pathway generator and predictions of associated reaction rate constants. Previously, we reported a reaction pathway generator that can enumerate the most important elementary reactions for aliphatic compounds. For the reaction rate constant predictor, we develop linear free energy relationships (LFERs) between aqueous phase literature-reported HO(•) reaction rate constants and theoretically calculated free energies of activation for H-atom abstraction from a C-H bond and HO(•) addition to alkenes. The theoretical method uses ab initio quantum mechanical calculations, Gaussian 1-3, for gas phase reactions and a solvation method, COSMO-RS theory, to estimate the impact of water. Theoretically calculated free energies of activation are found to be within approximately ±3 kcal/mol of experimental values. Considering errors that arise from quantum mechanical calculations and experiments, this should be within the acceptable errors. The established LFERs are used to predict the HO(•) reaction rate constants within a factor of 5 from the experimental values. This approach may be applied to other reaction mechanisms to establish a library of rate constant predictions for kinetic modeling of AOPs. PMID:21410278

  19. Time-frequency analysis of nonstationary vibration signals for deployable structures by using the constant-Q nonstationary gabor transform

    NASA Astrophysics Data System (ADS)

    Liu, Tao; Yan, Shaoze; Zhang, Wei

    2016-06-01

    Deployable structures have been widely used in on-orbit servicing spacecrafts, and the vibration properties of such structures have become increasingly important in the aerospace industry. The constant-Q nonstationary Gabor transform (CQ-NSGT) is introduced in this paper to accurately evaluate the variation in the frequency and amplitude of vibration signals along with time. First, an example signal is constructed on the basis of the vibration properties of deployable structures and is processed by the short-time Fourier transform, Wigner-Ville distribution, Hilbert-Huang transform, and CQ-NSGT. Results show that time and frequency resolutions are simultaneously fine only by employing CQ-NSGT. Subsequently, a zero padding operation is conducted to correct the calculation error at the end of the transform results. Finally, a set of experimental devices is constructed. The vibration signal of the experimental mode is processed by CQ-NSGT. On this basis, the experimental signal properties are discussed. This time-frequency method may be useful for formulating the dynamics for complex deployable structures.

  20. Recovery and radiation corrections and time constants of several sizes of shielded and unshielded thermocouple probes for measuring gas temperature

    NASA Technical Reports Server (NTRS)

    Glawe, G. E.; Holanda, R.; Krause, L. N.

    1978-01-01

    Performance characteristics were experimentally determined for several sizes of a shielded and unshielded thermocouple probe design. The probes are of swaged construction and were made of type K wire with a stainless steel sheath and shield and MgO insulation. The wire sizes ranged from 0.03- to 1.02-mm diameter for the unshielded design and from 0.16- to 0.81-mm diameter for the shielded design. The probes were tested through a Mach number range of 0.2 to 0.9, through a temperature range of room ambient to 1420 K, and through a total-pressure range of 0.03 to 0.2.2 MPa (0.3 to 22 atm). Tables and graphs are presented to aid in selecting a particular type and size. Recovery corrections, radiation corrections, and time constants were determined.

  1. New Quasar Studies Keep Fundamental Physical Constant Constant

    NASA Astrophysics Data System (ADS)

    2004-03-01

    atoms together and the way light interacts with atoms. But are these fundamental physical constants really constant? Are those numbers always the same, everywhere in the Universe and at all times? This is not as naive a question as it may seem. Contemporary theories of fundamental interactions, such as the Grand Unification Theory or super-string theories that treat gravity and quantum mechanics in a consistent way, not only predict a dependence of fundamental physical constants with energy - particle physics experiments have shown the fine structure constant to grow to a value of about 1/128 at high collision energies - but allow for their cosmological time and space variations. A time dependence of the fundamental constants could also easily arise if, besides the three space dimensions, there exist more hidden dimensions. Already in 1955, the Russian physicist Lev Landau considered the possibility of a time dependence of alpha. In the late 1960s, George Gamow in the United States suggested that the charge of the electron, and therefore also alpha, may vary. It is clear however that such changes, if any, cannot be large or they would already have been detected in comparatively simple experiments. Tracking these possible changes thus requires the most sophisticated and precise techniques. Looking back in time In fact, quite strong constraints are already known to exist for the possible variation of the fine structure constant alpha. One such constraint is of geological nature. It is based on measures taken in the ancient natural fission reactor located near Oklo (Gabon, West Africa) and which was active roughly 2,000 million years ago. By studying the distribution of a given set of elements - isotopes of the rare earths, for example of samarium - which were produced by the fission of uranium, one can estimate whether the physical process happened at a faster or slower pace than we would expect it nowadays. Thus we can measure a possible change of the value of the

  2. Chemotactic response with a constant delay-time mechanism in Ciona spermatozoa revealed by a high time resolution analysis of flagellar motility.

    PubMed

    Miyashiro, Daisuke; Shiba, Kogiku; Miyashita, Tahahiro; Baba, Shoji A; Yoshida, Manabu; Kamimura, Shinji

    2015-01-01

    During their chemotactic swimming toward eggs, sperm cells detect their species-specific chemoattractant and sense concentration gradients by unknown mechanisms. After sensing the attractant, sperm cells commonly demonstrate a series of responses involving different swimming patterns by changing flagellar beats, gradually approaching a swimming path toward the eggs, which is the source of chemoattractants. Shiba et al. observed a rapid increase in intracellular Ca(2+) concentrations in Ciona spermatozoa after sensing chemoattractants; however, the biochemical processes occurring inside the sperm cells are unclear. In the present study, we focused on the timing and sensing mechanism of chemical signal detection in Ciona. One of the most crucial problems to be solved is defining the initial epoch of chemotactic responses. We adopted a high rate of video recording (600 Hz) for detailed analysis of sperm motion and a novel method for detecting subtle signs of beat forms and moving paths of sperm heads. From these analyses, we estimated a virtual sensing point of the attractant before initiation of motility responses and found that the time delay from sensing to motility responses was almost constant. To evaluate the efficiency of this constant delay model, we performed computer simulation of chemotactic behaviors of Ciona spermatozoa. PMID:25572419

  3. SmB6 electron-phonon coupling constant from time- and angle-resolved photoelectron spectroscopy

    NASA Astrophysics Data System (ADS)

    Sterzi, A.; Crepaldi, A.; Cilento, F.; Manzoni, G.; Frantzeskakis, E.; Zacchigna, M.; van Heumen, E.; Huang, Y. K.; Golden, M. S.; Parmigiani, F.

    2016-08-01

    SmB6 is a mixed valence Kondo system resulting from the hybridization between localized f electrons and delocalized d electrons. We have investigated its out-of-equilibrium electron dynamics by means of time- and angle-resolved photoelectron spectroscopy. The transient electronic population above the Fermi level can be described by a time-dependent Fermi-Dirac distribution. By solving a two-temperature model that well reproduces the relaxation dynamics of the effective electronic temperature, we estimate the electron-phonon coupling constant λ to range from 0.13 ±0.03 to 0.04 ±0.01 . These extremes are obtained assuming a coupling of the electrons with either a phonon mode at 10 or 19 meV. A realistic value of the average phonon energy will give an actual value of λ within this range. Our results provide an experimental report on the material electron-phonon coupling, contributing to both the electronic transport and the macroscopic thermodynamic properties of SmB6.

  4. Reduction of methylene green by EDTA: a relation between dielectric constant of medium and activated state.

    PubMed

    Qamar, Noshab; Azmat, Rafia; Naz, Raheela

    2013-01-01

    Kinetics of an alkaline reduction of the methylene green with ethylenediaminetetraaceticacid (EDTA) as a role of dielectric constant of the medium with anecdotal ionic strength in a diverse solvent system (aqueous mixtures of methanol) (10-30%) was studied by measuring the specific rate constant of the reaction spectrophotometrically at λ (max) = 660nm. An effort has been made to give an elucidation of vital role of dielectric constant of the medium captivating into reflection of single sphere and double sphere complex in reaction assortment. This investigation leads to disclose that single sphere complex of the dye and reductant was found to be the most suitable complex existed in a varied organic solvent. The deviation of the theoretical values from experimental results for single sphere and double sphere complex model in the presence of an alkali and nitrate ions were justified through HPLC analysis. HPLC analysis recommended that a considerable amount of the dye degrades in the existence of nitrate ion and alkali and additional peaks which may be of by-product were obtained. This leads to confirm the non identical values of single sphere and double sphere model in the occurrence of nitrate and an alkali. Rate of deletion of color showed a linear liaison with respect to water content below 30% and temperature between 20-40(o)C whereas an increase in the concentration of organic solvent showed the inhibition of dye decoloration at given optimum condition. Therefore study was restricted up to 30% of methanol binary mixtures. A mechanism of reduction of dye has been proposed based on verdict.

  5. The time scale test for Ω: the inverse Hubble constant compared with the age of the universe.

    NASA Astrophysics Data System (ADS)

    Sandage, A.; Tammann, G. A.; Saha, A.

    1998-12-01

    The status of the HST program to calibrate the absolute magnitude at maximum of non-peculiar Type Ia supernovae is reviewed. Assuming, in first approximation, that SNe Ia are perfect standard candles gives an interim calibration, based on seven SNe Ia in six galaxies for which one has Cepheid distances, of >MB(max)< = -19.52±0.07, >MV(max)< = -19.48±0.07. Applying these calibrations to the Hubble diagram of 52 fiducial SNe Ia with good photometric data, and using a correction of 0.08 mag to an earlier adopted Cepheid period-luminosity relation gives H0 = 55±5 km s-1Mpc-1. Three other methods (via the Virgo cluster distance tied to the global expansion frame, the luminosity function of field spirals calibrated via Cepheids, and the physical methods using gravitational lenses, the Sunyaev-Zel'dovich effect, and expanding SN envelopes) confirm the long distance scale that is implied by this value. Second-parameter corrections to the supernovae method depending on decay rate affect this solution for H0 by, at most, 5%. A critique is given of the "Key Project" result that H0 > 70 (Freedman et al., 1998). Disagreements with their precepts are discussed. The Key Project results, reduced to the Virgo cluster distance of 21.5 Mpc, gives H0 = 55 km s-1Mpc-1. Adopting 13.5 Gyr for the time since the beginning of the expansion gives a timing test value of Ω(total) = 0.44 (-0.37,+1.16). This shows that the timing test for Omega, although powerful in principle because it measures the total mass, is presently impotent because the errors in H0 and Tu are too large. The principal result is that there is no time scale crisis in Big Bang cosmology, sans cosmological constant, because H0-1 > Tu decisively, using the long distance scale derived here.

  6. Cryogenic liquid hydrogen reorientation activated by constant reverse gravity acceleration of geyser initiation

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Shyu, K. L.

    1990-01-01

    A key objective for cryogenic fluid management in a spacecraft propulsion system is development of the technology necessary for acquisition or positioning of liquid outflow or vapor venting. Numerical simulation of positive liquid acquisition is attempted by introducing a reverse gravity acceleration from the propulsive thrust of auxiliary engines which exceeds critical value for the initiation of a geyser. Based on the computer simulation of flow fields during the course of fluid reorientation, six dimensionless parameters resulted. These parameters hold near-constant values through the entire range of liquid filled levels, from 30 to 80 percent, during the course of fluid reorientation.

  7. Constant reverse thrust activated reorientation of liquid hydrogen with Geyser initiation

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Shyu, K. L.

    1992-01-01

    A key objective of the cryogenic fluid management of the spacecraft propulsion system is to develop the technology necessary for acquisition or positioning of liquid outflow or vapor venting. Numerical simulation of positive liquid acquisition is attempted by introducing reverse gravity acceleration, resulting from the propulsive thrust of auxiliary engines, which exceeds critical value for the initiation of geyser. Based on the computer simulation of flowfields during the course of fluid reorientation, six dimensionless parameters resulted in this study. It shows that these parameters hold near-constant values through the entire ranges of liquid filled levels, from 30-80 percent, during the course of fluid reorientation.

  8. Gravity currents produced by constant and time varying inflow in a circular cross-section channel: Experiments and theory

    NASA Astrophysics Data System (ADS)

    Longo, S.; Ungarish, M.; Di Federico, V.; Chiapponi, L.; Addona, F.

    2016-04-01

    We investigate high-Reynolds number gravity currents (GC) in a horizontal channel of circular cross-section. We focus on GC sustained by constant or time varying inflow (volume of injected fluid ∝ tα, with α = 1 and α > 1). The novelty of our work is in the type of the gravity currents: produced by influx/outflux boundary conditions, and propagation in circular (or semi-circular) channel. The objective is to elucidate the main propagation features and correlate them to the governing dimensionless parameters; to this end, we use experimental observations guided by shallow-water (SW) theoretical models. The system is of Boussinesq type with the denser fluid (salt water) injected into the ambient fluid (tap water) at one end section of a circular tube of 19 cm diameter and 605 cm long. The ambient fluid fills the channel of radius r* up to a given height H* = βr* (0 < β < 2) where it is open to the atmosphere. This fluid is displaced by the intruding current and outflows either at the same or at the opposite end-side of the channel. The two different configurations (with return and no-return flow) allow to analyze the impact of the motion of the ambient fluid on the front speed of the intruding current. For Q larger than some threshold value, the current is expected theoretically to undergo a choking process which limits the speed/thickness of propagation. Two series of experiments were conducted with constant and time varying inflow. The choking effect was observed, qualitatively, in both series. The theory correctly predicts the qualitative behavior, but systematically overestimates the front speed of the current (consistent with previously-published data concerning rectangular and non-rectangular cross-sections), with larger discrepancies for the no-return flow case. These discrepancies are mainly due to: (i) the variations of the free-surface of the ambient fluid with respect to its nominal value (the theoretical model assumes a fixed free-slip top of the

  9. Effective charge on acetylcholinesterase active sites determined from the ionic strength dependence of association rate constants with cationic ligands.

    PubMed

    Nolte, H J; Rosenberry, T L; Neumann, E

    1980-08-01

    The reaction of the specific fluorescent cationic ligand N-methylacridinium with the active site of 11S acetylcholinesterase from electric eel was monitored by temperature-jump relaxation kinetics at a variety of ionic strengths. The ionic strength dependence of the bimolecular association rate constant is analyzed with a Brønsted-Debye-Hückel expression and leads to estimates of the association rate constant at zero ionic strength of K120 = 1.1 X 10(10) M-1 S-1 at 25 degrees C and the net charge number of the enzyme active site of ZE = -6.3. The ionic strength dependence of the second-order hydrolysis rate constant kcat/Kapp for acetylthiocholine under steady-state conditions is also very pronounced and indicates a value of ZE = -9. Thus, a large effective negative charge on the enzyme active site appears to be a general characteristic of its interaction with cationic ligands. The ionic strength dependence of Kcat/Kapp is identical with that of sodium chloride, sodium phosphate, and sodium citrate, thus ruling out any possibility that the phenomena arise from a specific, partially competitive binding of Na+ to the enzyme active site. Substitution of the calculated electrostatic parameters into theoretical equations indicates that the most significant effect of these ZE values is a 2-3 order of magnitude reduction in the rate constant for dissociation of the initial ligand-enzyme encounter complex; this decrease renders the bimolecular reaction diffusion controlled. The high value of k120 and the space requirements of six to nine charged groups suggest that regions of the enzyme surface area larger than the catalytic sites themselves are effective in trapping cationic ligands.

  10. Quantitative Structure-Activity Relationships Study on the Rate Constants of Polychlorinated Dibenzo-p-Dioxins with OH Radical

    PubMed Central

    Qi, Chuansong; Zhang, Chenxi; Sun, Xiaomin

    2015-01-01

    The OH-initiated reaction rate constants (kOH) are of great importance to measure atmospheric behaviors of polychlorinated dibenzo-p-dioxins (PCDDs) in the environment. The rate constants of 75 PCDDs with the OH radical at 298.15 K have been calculated using high level molecular orbital theory, and the rate constants (kα, kβ, kγ and kOH) were further analyzed by the quantitative structure-activity relationships (QSAR) study. According to the QSAR models, the relations between rate constants and the numbers and positions of Cl atoms, the energy of the highest occupied molecular orbital (EHOMO), the energy of the lowest unoccupied molecular orbital (ELUMO), the difference ΔEHOMO-LUMO between EHOMO and ELUMO, and the dipole of oxidizing agents (D) were discussed. It was found that EHOMO is the main factor in the kOH. The number of Cl atoms is more effective than the number of relative position of these Cl atoms in the kOH. The kOH decreases with the increase of the substitute number of Cl atoms. PMID:26274950

  11. Photodynamic activation of ion transport through lipid membranes and its correlation with an increased dielectric constant of the membrane.

    PubMed

    Killig, Frank; Stark, Günther

    2002-08-19

    Illumination of biological membranes with visible light in the presence of membrane-active sensitizers (e.g. rose bengal) is known to inactivate transport proteins such as ion channels and ion pumps. In some cases, however, illumination gives rise to an activation of transport. This is shown here for ion channels formed by alamethicin in lipid membranes, and for porin channels, which were isolated from the outer membrane of E. coli (OmpC) and from the outer membrane of mitochondria (VDAC) and were reconstituted in lipid membranes. An activation (in the form of an increased conductance) was also observed in the presence of the cation carriers valinomycin and nonactin. The activation phenomena were only present, if the membranes were made from lipids containing unsaturated double bonds. Activation was reduced in the presence of the antioxidant vitamin E. We suggest that the activation of the different transport systems has a common physical basis, namely an increase of the dielectric constant, epsilon(m), of the membrane interior by the presence of polar oxidation products of photodynamically induced lipid peroxidation. Experimental evidence for an enhanced dielectric constant was obtained from the finding of a light-induced increase of the membrane capacitance in the presence of rose bengal.

  12. The relationship between trunk muscle activation and trunk stiffness: examining a non-constant stiffness gain.

    PubMed

    Brown, Stephen H M; McGill, Stuart M

    2010-12-01

    The relationship between muscle activation, force and stiffness needs to be known to interpret the stability state of the spine. To test the relationship between these variables, a quick release approach was used to match quantified torso stiffness with an EMG activation-based estimate of individual muscle stiffnesses. The relationship between activation, force and stiffness was modelled as k = q x F/l, where k, F and l are muscle stiffness, force and length, respectively, and q is the dimensionless stiffness gain relating these variables. Under the tested experimental scenario, the 'stiffness gain', q, which linked activation with stiffness, demonstrated a decreasing trend with increasing levels of torso muscle activation. This highlights the likelihood that the choice of a single q value may be over simplistic to relate force to stiffness in muscles that control the spine. This has implications for understanding the potential for spine instability in situations requiring high muscular demand.

  13. Searching for space-time variation of the fine structure constant using QSO spectra: overview and future prospects

    NASA Astrophysics Data System (ADS)

    Berengut, J. C.; Dzuba, V. A.; Flambaum, V. V.; King, J. A.; Kozlov, M. G.; Murphy, M. T.; Webb, J. K.

    2010-11-01

    Current theories that seek to unify gravity with the other fundamental interactions suggest that spatial and temporal variation of fundamental constants is a possibility, or even a necessity, in an expanding Universe. Several studies have tried to probe the values of constants at earlier stages in the evolution of the Universe, using tools such as big-bang nucleosynthesis, the Oklo natural nuclear reactor, quasar absorption spectra, and atomic clocks (see, e.g. Flambaum & Berengut (2009)).

  14. The effect of concentration- and temperature-dependent dielectric constant on the activity coefficient of NaCl electrolyte solutions

    SciTech Connect

    Valiskó, Mónika; Boda, Dezső

    2014-06-21

    Our implicit-solvent model for the estimation of the excess chemical potential (or, equivalently, the activity coefficient) of electrolytes is based on using a dielectric constant that depends on the thermodynamic state, namely, the temperature and concentration of the electrolyte, ε(c, T). As a consequence, the excess chemical potential is split into two terms corresponding to ion-ion (II) and ion-water (IW) interactions. The II term is obtained from computer simulation using the Primitive Model of electrolytes, while the IW term is estimated from the Born treatment. In our previous work [J. Vincze, M. Valiskó, and D. Boda, “The nonmonotonic concentration dependence of the mean activity coefficient of electrolytes is a result of a balance between solvation and ion-ion correlations,” J. Chem. Phys. 133, 154507 (2010)], we showed that the nonmonotonic concentration dependence of the activity coefficient can be reproduced qualitatively with this II+IW model without using any adjustable parameter. The Pauling radii were used in the calculation of the II term, while experimental solvation free energies were used in the calculation of the IW term. In this work, we analyze the effect of the parameters (dielectric constant, ionic radii, solvation free energy) on the concentration and temperature dependence of the mean activity coefficient of NaCl. We conclude that the II+IW model can explain the experimental behavior using a concentration-dependent dielectric constant and that we do not need the artificial concept of “solvated ionic radius” assumed by earlier studies.

  15. The effect of concentration- and temperature-dependent dielectric constant on the activity coefficient of NaCl electrolyte solutions.

    PubMed

    Valiskó, Mónika; Boda, Dezső

    2014-06-21

    Our implicit-solvent model for the estimation of the excess chemical potential (or, equivalently, the activity coefficient) of electrolytes is based on using a dielectric constant that depends on the thermodynamic state, namely, the temperature and concentration of the electrolyte, ε(c, T). As a consequence, the excess chemical potential is split into two terms corresponding to ion-ion (II) and ion-water (IW) interactions. The II term is obtained from computer simulation using the Primitive Model of electrolytes, while the IW term is estimated from the Born treatment. In our previous work [J. Vincze, M. Valiskó, and D. Boda, "The nonmonotonic concentration dependence of the mean activity coefficient of electrolytes is a result of a balance between solvation and ion-ion correlations," J. Chem. Phys. 133, 154507 (2010)], we showed that the nonmonotonic concentration dependence of the activity coefficient can be reproduced qualitatively with this II+IW model without using any adjustable parameter. The Pauling radii were used in the calculation of the II term, while experimental solvation free energies were used in the calculation of the IW term. In this work, we analyze the effect of the parameters (dielectric constant, ionic radii, solvation free energy) on the concentration and temperature dependence of the mean activity coefficient of NaCl. We conclude that the II+IW model can explain the experimental behavior using a concentration-dependent dielectric constant and that we do not need the artificial concept of "solvated ionic radius" assumed by earlier studies.

  16. A procedure to find thermodynamic equilibrium constants for CO2 and CH4 adsorption on activated carbon.

    PubMed

    Trinh, T T; van Erp, T S; Bedeaux, D; Kjelstrup, S; Grande, C A

    2015-03-28

    Thermodynamic equilibrium for adsorption means that the chemical potential of gas and adsorbed phase are equal. A precise knowledge of the chemical potential is, however, often lacking, because the activity coefficient of the adsorbate is not known. Adsorption isotherms are therefore commonly fitted to ideal models such as the Langmuir, Sips or Henry models. We propose here a new procedure to find the activity coefficient and the equilibrium constant for adsorption which uses the thermodynamic factor. Instead of fitting the data to a model, we calculate the thermodynamic factor and use this to find first the activity coefficient. We show, using published molecular simulation data, how this procedure gives the thermodynamic equilibrium constant and enthalpies of adsorption for CO2(g) on graphite. We also use published experimental data to find similar thermodynamic properties of CO2(g) and of CH4(g) adsorbed on activated carbon. The procedure gives a higher accuracy in the determination of enthalpies of adsorption than ideal models do.

  17. Mouse Activity across Time Scales: Fractal Scenarios

    PubMed Central

    Lima, G. Z. dos Santos; Lobão-Soares, B.; do Nascimento, G. C.; França, Arthur S. C.; Muratori, L.; Ribeiro, S.; Corso, G.

    2014-01-01

    In this work we devise a classification of mouse activity patterns based on accelerometer data using Detrended Fluctuation Analysis. We use two characteristic mouse behavioural states as benchmarks in this study: waking in free activity and slow-wave sleep (SWS). In both situations we find roughly the same pattern: for short time intervals we observe high correlation in activity - a typical 1/f complex pattern - while for large time intervals there is anti-correlation. High correlation of short intervals ( to : waking state and to : SWS) is related to highly coordinated muscle activity. In the waking state we associate high correlation both to muscle activity and to mouse stereotyped movements (grooming, waking, etc.). On the other side, the observed anti-correlation over large time scales ( to : waking state and to : SWS) during SWS appears related to a feedback autonomic response. The transition from correlated regime at short scales to an anti-correlated regime at large scales during SWS is given by the respiratory cycle interval, while during the waking state this transition occurs at the time scale corresponding to the duration of the stereotyped mouse movements. Furthermore, we find that the waking state is characterized by longer time scales than SWS and by a softer transition from correlation to anti-correlation. Moreover, this soft transition in the waking state encompass a behavioural time scale window that gives rise to a multifractal pattern. We believe that the observed multifractality in mouse activity is formed by the integration of several stereotyped movements each one with a characteristic time correlation. Finally, we compare scaling properties of body acceleration fluctuation time series during sleep and wake periods for healthy mice. Interestingly, differences between sleep and wake in the scaling exponents are comparable to previous works regarding human heartbeat. Complementarily, the nature of these sleep-wake dynamics could lead to a better

  18. Time-driven activity-based costing.

    PubMed

    Kaplan, Robert S; Anderson, Steven R

    2004-11-01

    In the classroom, activity-based costing (ABC) looks like a great way to manage a company's limited resources. But executives who have tried to implement ABC in their organizations on any significant scale have often abandoned the attempt in the face of rising costs and employee irritation. They should try again, because a new approach sidesteps the difficulties associated with large-scale ABC implementation. In the revised model, managers estimate the resource demands imposed by each transaction, product, or customer, rather than relying on time-consuming and costly employee surveys. This method is simpler since it requires, for each group of resources, estimates of only two parameters: how much it costs per time unit to supply resources to the business's activities (the total overhead expenditure of a department divided by the total number of minutes of employee time available) and how much time it takes to carry out one unit of each kind of activity (as estimated or observed by the manager). This approach also overcomes a serious technical problem associated with employee surveys: the fact that, when asked to estimate time spent on activities, employees invariably report percentages that add up to 100. Under the new system, managers take into account time that is idle or unused. Armed with the data, managers then construct time equations, a new feature that enables the model to reflect the complexity of real-world operations by showing how specific order, customer, and activity characteristics cause processing times to vary. This Tool Kit uses concrete examples to demonstrate how managers can obtain meaningful cost and profitability information, quickly and inexpensively. Rather than endlessly updating and maintaining ABC data,they can now spend their time addressing the deficiencies the model reveals: inefficient processes, unprofitable products and customers, and excess capacity.

  19. Time-driven activity-based costing.

    PubMed

    Kaplan, Robert S; Anderson, Steven R

    2004-11-01

    In the classroom, activity-based costing (ABC) looks like a great way to manage a company's limited resources. But executives who have tried to implement ABC in their organizations on any significant scale have often abandoned the attempt in the face of rising costs and employee irritation. They should try again, because a new approach sidesteps the difficulties associated with large-scale ABC implementation. In the revised model, managers estimate the resource demands imposed by each transaction, product, or customer, rather than relying on time-consuming and costly employee surveys. This method is simpler since it requires, for each group of resources, estimates of only two parameters: how much it costs per time unit to supply resources to the business's activities (the total overhead expenditure of a department divided by the total number of minutes of employee time available) and how much time it takes to carry out one unit of each kind of activity (as estimated or observed by the manager). This approach also overcomes a serious technical problem associated with employee surveys: the fact that, when asked to estimate time spent on activities, employees invariably report percentages that add up to 100. Under the new system, managers take into account time that is idle or unused. Armed with the data, managers then construct time equations, a new feature that enables the model to reflect the complexity of real-world operations by showing how specific order, customer, and activity characteristics cause processing times to vary. This Tool Kit uses concrete examples to demonstrate how managers can obtain meaningful cost and profitability information, quickly and inexpensively. Rather than endlessly updating and maintaining ABC data,they can now spend their time addressing the deficiencies the model reveals: inefficient processes, unprofitable products and customers, and excess capacity. PMID:15559451

  20. Neutron activation-based gamma scintigraphy in pharmacoscintigraphic evaluation of an Egalet constant-release drug delivery system.

    PubMed

    Marvola, Janne; Kanerva, Hanna; Slot, Lillian; Lipponen, Maija; Kekki, Tommi; Hietanen, Heikki; Mykkänen, Sirpa; Ariniemi, Kari; Lindevall, Kai; Marvola, Martti

    2004-08-20

    This paper is a report from a pharmacoscintigraphic study with an Egalet constant-release system containing caffeine and natural abundance samarium oxide. First the formulation was tested in vitro to clarify integrity during irradiation in the nuclear reactor. Then six healthy male volunteers were enrolled into the in vivo study. The in vitro release of caffeine obeyed all the time linear zero-order kinetics. The in vivo release of radioactive Sm2O3 consisted of three consequent linear phases with different slopes. The release rate was fastest while the product was in the small intestine and slowest when the product was in the descending colon. In terms of the bioavailability of caffeine, the most important factor seemed to be the residence time in the ascending and transverse colon. A long residence time in these sections led to high AUC values for caffeine. PMID:15288338

  1. Neutron activation-based gamma scintigraphy in pharmacoscintigraphic evaluation of an Egalet constant-release drug delivery system.

    PubMed

    Marvola, Janne; Kanerva, Hanna; Slot, Lillian; Lipponen, Maija; Kekki, Tommi; Hietanen, Heikki; Mykkänen, Sirpa; Ariniemi, Kari; Lindevall, Kai; Marvola, Martti

    2004-08-20

    This paper is a report from a pharmacoscintigraphic study with an Egalet constant-release system containing caffeine and natural abundance samarium oxide. First the formulation was tested in vitro to clarify integrity during irradiation in the nuclear reactor. Then six healthy male volunteers were enrolled into the in vivo study. The in vitro release of caffeine obeyed all the time linear zero-order kinetics. The in vivo release of radioactive Sm2O3 consisted of three consequent linear phases with different slopes. The release rate was fastest while the product was in the small intestine and slowest when the product was in the descending colon. In terms of the bioavailability of caffeine, the most important factor seemed to be the residence time in the ascending and transverse colon. A long residence time in these sections led to high AUC values for caffeine.

  2. Cosmology with varying constants.

    PubMed

    Martins, Carlos J A P

    2002-12-15

    The idea of possible time or space variations of the 'fundamental' constants of nature, although not new, is only now beginning to be actively considered by large numbers of researchers in the particle physics, cosmology and astrophysics communities. This revival is mostly due to the claims of possible detection of such variations, in various different contexts and by several groups. I present the current theoretical motivations and expectations for such variations, review the current observational status and discuss the impact of a possible confirmation of these results in our views of cosmology and physics as a whole.

  3. Sunspot Time Series: Passive and Active Intervals

    NASA Astrophysics Data System (ADS)

    Zięba, S.; Nieckarz, Z.

    2014-07-01

    Solar activity slowly and irregularly decreases from the first spotless day (FSD) in the declining phase of the old sunspot cycle and systematically, but also in an irregular way, increases to the new cycle maximum after the last spotless day (LSD). The time interval between the first and the last spotless day can be called the passive interval (PI), while the time interval from the last spotless day to the first one after the new cycle maximum is the related active interval (AI). Minima of solar cycles are inside PIs, while maxima are inside AIs. In this article, we study the properties of passive and active intervals to determine the relation between them. We have found that some properties of PIs, and related AIs, differ significantly between two group of solar cycles; this has allowed us to classify Cycles 8 - 15 as passive cycles, and Cycles 17 - 23 as active ones. We conclude that the solar activity in the PI declining phase (a descending phase of the previous cycle) determines the strength of the approaching maximum in the case of active cycles, while the activity of the PI rising phase (a phase of the ongoing cycle early growth) determines the strength of passive cycles. This can have implications for solar dynamo models. Our approach indicates the important role of solar activity during the declining and the rising phases of the solar-cycle minimum.

  4. Leisure time activities of elementary school children.

    PubMed

    Harrell, J S; Gansky, S A; Bradley, C B; McMurray, R G

    1997-01-01

    The three most common leisure time activities of 2,200 third and fourth grade children (mean age 8.8 + 0.8; 50.7% girls) and the association of the intensity levels of those activities with demographic variables and risk factors for cardiovascular disease are reported. Activities reported most often by boys were playing video games (33%), playing football (32%), bicycling (31%), watching television (28%), and playing basketball (26%). The girls reported doing homework (39%), bicycling (31%), watching television (30%), dancing (27%), and reading (23%). Overall, the children, especially girls, reported fairly sedentary activities, with an average metabolic equivalent level of 4.2 for girls and 4.8 for boys. Among boys, African Americans reported more vigorous activities than Whites, but the activities reported by White girls were somewhat more vigorous than those reported by non-White girls. Children from a higher socioeconomic status (SES), especially boys, reported a greater proportion of sedentary activities than lower SES children. The risk factors of cholesterol, blood pressure, skinfold thickness, and body mass index were not significantly associated with total activity score. However, significantly more nonobese than obese children reported a vigorous (high-intensity) activity as one of their top three activities.

  5. Preference as a Function of Active Interresponse Times: A Test of the Active Time Model

    ERIC Educational Resources Information Center

    Misak, Paul; Cleaveland, J. Mark

    2011-01-01

    In this article, we describe a test of the active time model for concurrent variable interval (VI) choice. The active time model (ATM) suggests that the time since the most recent response is one of the variables controlling choice in concurrent VI VI schedules of reinforcement. In our experiment, pigeons were trained in a multiple concurrent…

  6. cVEMP morphology changes with recording electrode position, but single motor unit activity remains constant.

    PubMed

    Rosengren, Sally M; Colebatch, James G; Borire, Adeniyi; Straumann, Dominik; Weber, Konrad P

    2016-04-15

    Cervical vestibular evoked myogenic potentials (cVEMPs) recorded over the lower quarter of the sternocleidomastoid (SCM) muscle in normal subjects may have opposite polarity to those recorded over the midpoint. It has thus been suggested that vestibular projections to the lower part of SCM might be excitatory rather than inhibitory. We tested the hypothesis that the SCM muscle receives both inhibitory and excitatory vestibular inputs. We recorded cVEMPs in 10 normal subjects with surface electrodes placed at multiple sites along the anterior (sternal) component of the SCM muscle. We compared several reference sites: sternum, ipsilateral and contralateral earlobes, and contralateral wrist. In five subjects, single motor unit responses were recorded at the upper, middle, and lower parts of the SCM muscle using concentric needle electrodes. The surface cVEMP had the typical positive-negative polarity at the midpoint of the SCM muscle. In all subjects, as the recording electrode was moved toward each insertion point, p13 amplitude became smaller and p13 latency increased, then the polarity inverted to a negative-positive waveform (n1-p1). Changing the reference site did not affect reflex polarity. There was a significant short-latency change in activity in 61/63 single motor units, and in each case this was a decrease or gap in firing, indicating an inhibitory reflex. Single motor unit recordings showed that the reflex was inhibitory along the entire SCM muscle. The cVEMP surface waveform inversion near the mastoid and sternal insertion points likely reflects volume conduction of the potential occurring with increasing distance from the motor point. PMID:26796756

  7. Matched elastic constants for a perfect helical planar state and a fast switching time in chiral nematic liquid crystals.

    PubMed

    Yu, Meina; Zhou, Xiaochen; Jiang, Jinghua; Yang, Huai; Yang, Deng-Ke

    2016-05-11

    Chiral nematic liquid crystals possess a self-assembled helical structure and exhibit unique selective reflection in visible and infrared light regions. Their optical properties can be electrically tuned. The tuning involves the unwinding and restoring of the helical structure. We carried out an experimental study on the mechanism of the restoration of the helical structure. We constructed chiral nematic liquid crystals with variable elastic constants by doping bent-dimers and studied their impact on the restoration. With matched twist and bend elastic constants, the helical structure can be restored dramatically fast from the field-induced homeotropic state. Furthermore, defects can be eliminated to produce a perfect planar state which exhibits high selective reflection.

  8. A semi-empirical equation for the response time of in-plane switching liquid crystal display and measurement of twist elastic constant

    NASA Astrophysics Data System (ADS)

    Xu, Daming; Peng, Fenglin; Tan, Guanjun; He, Juan; Wu, Shin-Tson

    2015-05-01

    A semi-empirical equation is developed to characterize the optical decay time of in-plane switching (IPS) and fringe field switching (FFS) liquid crystal displays. This equation takes the effects of elastic constants, cell gap, liquid crystal material, rubbing angle, and anchoring strength into account simultaneously. Good agreement between simulation and experiment is obtained. Moreover, this equation can be used to measure the twist elastic constant K22 of liquid crystals. The measured temperature-dependent K22 values of 5CB agree well with previously published results. Hence, our equation not only describes the response time of IPS and FFS cells but also provides a simple yet accurate method to determine the twist elastic constant of liquid crystal materials.

  9. Rate Constants and Activation Energies for Gas‐Phase Reactions of Three Cyclic Volatile Methyl Siloxanes with the Hydroxyl Radical

    PubMed Central

    Safron, Andreas; Strandell, Michael; Kierkegaard, Amelie

    2015-01-01

    ABSTRACT Reaction with hydroxyl radicals (OH) is the major pathway for removal of cyclic volatile methyl siloxanes (cVMS) from air. We present new measurements of second‐order rate constants for reactions of the cVMS octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) with OH determined at temperatures between 313 and 353 K. Our measurements were made using the method of relative rates with cyclohexane as a reference substance and were conducted in a 140‐mL gas‐phase reaction chamber with online mass spectrometry analysis. When extrapolated to 298 K, our measured reaction rate constants of D4 and D5 with the OH radical are 1.9 × 10−12 (95% confidence interval (CI): (1.7–2.2) × 10−12) and 2.6 × 10−12 (CI: (2.3–2.9) × 10−12) cm3 molecule−1 s−1, respectively, which are 1.9× and 1.7× faster than previous measurements. Our measured rate constant for D6 is 2.8 × 10−12 (CI: (2.5–3.2) × 10−12) cm3 molecule−1 s−1 and to our knowledge there are no comparable laboratory measurements in the literature. Reaction rates for D5 were 33% higher than for D4 (CI: 30–37%), whereas the rates for D6 were only 8% higher than for D5 (CI: 5–10%). The activation energies of the reactions of D4, D5, and D6 with OH were not statistically different and had a value of 4300 ± 2800 J/mol.

  10. Mouse activity across time scales: fractal scenarios.

    PubMed

    Lima, G Z dos Santos; Lobão-Soares, B; do Nascimento, G C; França, Arthur S C; Muratori, L; Ribeiro, S; Corso, G

    2014-01-01

    In this work we devise a classification of mouse activity patterns based on accelerometer data using Detrended Fluctuation Analysis. We use two characteristic mouse behavioural states as benchmarks in this study: waking in free activity and slowwave sleep (SWS). In both situations we find roughly the same pattern: for short time intervals we observe high correlation in activity--a typical 1/f complex pattern--while for large time intervals there is anti-correlation. High correlation of short intervals (0.01 s to 2 s: waking state and 0.01 s to 0.1 s: SWS) is related to highly coordinated muscle activity. In the waking state we associate high correlation both to muscle activity and to mouse stereotyped movements (grooming, waking, etc.). On the other side, the observed anti-correlation over large time scales (30 s to 300 s: waking state and 0.3 s to 5 s: SWS) during SWS appears related to a feedback autonomic response. The transition from correlated regime at short scales to an anti-correlated regime at large scales during SWS is given by the respiratory cycle interval, while during the waking state this transition occurs at the time scale corresponding to the duration of the stereotyped mouse movements. Furthermore, we find that the waking state is characterized by longer time scales than SWS and by a softer transition from correlation to anticorrelation. Moreover, this soft transition in the waking state encompass a behavioural time scale window that gives rise to a multifractal pattern. We believe that the observed multifractality in mouse activity is formed by the integration of several stereotyped movements each one with a characteristic time correlation. Finally, we compare scaling properties of body acceleration fluctuation time series during sleep and wake periods for healthy mice. Interestingly, differences between sleep and wake in the scaling exponents are comparable to previous works regarding human heartbeat. Complementarily, the nature of these sleep

  11. Recognition of Short Time-Paired Activities

    NASA Astrophysics Data System (ADS)

    Chaminda, Hapugahage Thilak; Klyuev, Vitaly; Naruse, Keitaro; Osano, Minetada

    We undertake numerous activities in our daily life and for some of those we forget to complete the action as originally intended. Significant aspects while performing most of these actions might be: “pairing of both hands simultaneously” and “short time consumption”. In this work an attempt has been made to recognize those kinds of Paired Activities (PAs), which are easy to forget, and to provide a method to remind about uncompleted PAs. To represent PAs, a study was done on opening and closing of various bottles. A model to define PAs, which simulated the paired behavior of both hands, is proposed, called “Paired Activity Model” (PAM). To recognize PAs using PAM, Paired Activity Recognition Algorithm (PARA) was implemented. Paired motion capturing was done by accelerometers, which were worn by subjects on the wrist areas of both hands. Individual and correlative behavior of both hands was used to recognize exact PA among other activities. Artificial Neural Network (ANN) algorithm was used for data categorization in PARA. ANN significantly outperformed the support vector machine algorithm in real time evaluations. In the user-independent case, PARA achieved recognition rates of 96% for only target PAs and 91% for target PAs undertaken amidst unrelated activities.

  12. Comparison of Constant Time Delay and Simultaneous Prompting Procedures: Teaching Functional Sight Words to Students with Intellectual Disabilities and Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    Swain, Rasheeda; Lane, Justin D.; Gast, David L.

    2015-01-01

    Constant time delay (CTD) and simultaneous prompting (SP) are effective response prompting procedures for teaching students with moderate to severe disabilities. The purpose of this study was to compare the efficiency of CTD and SP when teaching functional sight words to four students, 8-11 years of age, with moderate intellectual disability (ID)…

  13. Effectiveness and Efficiency of Constant-Time Delay and Most-to-Least Prompt Procedures in Teaching Daily Living Skills to Children with Intellectual Disabilities

    ERIC Educational Resources Information Center

    Aykut, Cigil

    2012-01-01

    This study is aimed at comparing the effectiveness and efficiency of constant-time delay and most-to-least prompt procedures in teaching daily living skills to children with mental retardation. Adapted alternating treatment design was used. The outcome shows that both procedures were equally effective in teaching the daily living skills. However,…

  14. Comparison of Simultaneous Prompting and Constant Time Delay Procedures in Teaching Children with Autism the Responses to Questions about Personal Information

    ERIC Educational Resources Information Center

    Akmanoglu, Nurgul; Kurt, Onur; Kapan, Alper

    2015-01-01

    The aim of the current study was to compare simultaneous prompting (SP) and constant time delay (CTD) in terms of their effectiveness and efficiency in teaching children with autism how to respond to questions about personal information. The adapted alternating treatments model was used in the study. Three male students with autism aged 4, 6, and…

  15. Particle loading time and humidity effects on the efficiency of an N95 filtering facepiece respirator model under constant and inhalation cyclic flows.

    PubMed

    Mahdavi, Alireza; Haghighat, Fariborz; Bahloul, Ali; Brochot, Clothilde; Ostiguy, Claude

    2015-06-01

    It is necessary to investigate the efficiencies of filtering facepiece respirators (FFRs) exposed to ultrafine particles (UFPs) for long periods of time, since the particle loading time may potentially affect the efficiency of FFRs. This article aims to investigate the filtration efficiency for a model of electrostatic N95 FFRs with constant and 'inhalation-only' cyclic flows, in terms of particle loading time effect, using different humidity conditions. Filters were exposed to generated polydisperse NaCl particles. Experiments were performed mimicking an 'inhalation-only' scenario with a cyclic flow of 85 l min(-1) as the minute volume [or 170 l min(-1) as mean inhalation flow (MIF)] and for two constant flows of 85 and 170 l min(-1), under three relative humidity (RH) levels of 10, 50, and 80%. Each test was performed for loading time periods of 6h and the particle penetration (10-205.4nm in electrical mobility diameter) was measured once every 2h. For a 10% RH, the penetration of smaller size particles (<80nm), including the most penetrating particle size (MPPS), decreased over time for both constant and cyclic flows. For 50 and 80% RH levels, the changes in penetration were typically observed in an opposite direction with less magnitude. The penetrations at MPPS increased with respect to loading time under constant flow conditions (85 and 170 l min(-1)): it did not substantially increase under cyclic flows. The comparison of the cyclic flow (85 l min(-1) as minute volume) and constant flow equal to the cyclic flow minute volume indicated that, for all conditions the penetration was significantly less for the constant flow than that of cyclic flow. The comparison between the cyclic (170 l min(-1) as MIF) and constant flow equal to cyclic flow MIF indicated that, for the initial stage of loading, the penetrations were almost equal, but they were different for the final stages of the loading time. For a 10% RH, the penetration of a wide range of sizes was observed

  16. Particle loading time and humidity effects on the efficiency of an N95 filtering facepiece respirator model under constant and inhalation cyclic flows.

    PubMed

    Mahdavi, Alireza; Haghighat, Fariborz; Bahloul, Ali; Brochot, Clothilde; Ostiguy, Claude

    2015-06-01

    It is necessary to investigate the efficiencies of filtering facepiece respirators (FFRs) exposed to ultrafine particles (UFPs) for long periods of time, since the particle loading time may potentially affect the efficiency of FFRs. This article aims to investigate the filtration efficiency for a model of electrostatic N95 FFRs with constant and 'inhalation-only' cyclic flows, in terms of particle loading time effect, using different humidity conditions. Filters were exposed to generated polydisperse NaCl particles. Experiments were performed mimicking an 'inhalation-only' scenario with a cyclic flow of 85 l min(-1) as the minute volume [or 170 l min(-1) as mean inhalation flow (MIF)] and for two constant flows of 85 and 170 l min(-1), under three relative humidity (RH) levels of 10, 50, and 80%. Each test was performed for loading time periods of 6h and the particle penetration (10-205.4nm in electrical mobility diameter) was measured once every 2h. For a 10% RH, the penetration of smaller size particles (<80nm), including the most penetrating particle size (MPPS), decreased over time for both constant and cyclic flows. For 50 and 80% RH levels, the changes in penetration were typically observed in an opposite direction with less magnitude. The penetrations at MPPS increased with respect to loading time under constant flow conditions (85 and 170 l min(-1)): it did not substantially increase under cyclic flows. The comparison of the cyclic flow (85 l min(-1) as minute volume) and constant flow equal to the cyclic flow minute volume indicated that, for all conditions the penetration was significantly less for the constant flow than that of cyclic flow. The comparison between the cyclic (170 l min(-1) as MIF) and constant flow equal to cyclic flow MIF indicated that, for the initial stage of loading, the penetrations were almost equal, but they were different for the final stages of the loading time. For a 10% RH, the penetration of a wide range of sizes was observed

  17. Absolute rate constant determinations for the deactivation of O/1D/ by time resolved decay of O/1D/ yields O/3P/ emission

    NASA Technical Reports Server (NTRS)

    Davidson, J. A.; Sadowski, C. M.; Schiff, H. I.; Howard, C. J.; Schmeltekopf, A. L.; Jennings, D. A.; Streit, G. E.

    1976-01-01

    Absolute rate constants for the deactivation of O(1D) atoms by some atmospheric gases have been determined by observing the time-resolved emission of O(1D) at 630 nm. O(1D) atoms were produced by the dissociation of ozone via repetitive laser pulses at 266 nm. Absolute rate constants for the relaxation of O(1D) at 298 K are reported for N2, O2, CO2, O3, H2, D2, CH4, HCl, NH3, H2O, N2O, and Ne. The results obtained are compared with previous relative and absolute measurements reported in the literature.

  18. TOWARD A NEW GEOMETRIC DISTANCE TO THE ACTIVE GALAXY NGC 4258. III. FINAL RESULTS AND THE HUBBLE CONSTANT

    SciTech Connect

    Humphreys, E. M. L.; Reid, M. J.; Moran, J. M.; Greenhill, L. J.; Argon, A. L.

    2013-09-20

    We report a new geometric maser distance estimate to the active galaxy NGC 4258. The data for the new model are maser line-of-sight (LOS) velocities and sky positions from 18 epochs of very long baseline interferometry observations, and LOS accelerations measured from a 10 yr monitoring program of the 22 GHz maser emission of NGC 4258. The new model includes both disk warping and confocal elliptical maser orbits with differential precession. The distance to NGC 4258 is 7.60 {+-} 0.17 {+-} 0.15 Mpc, a 3% uncertainty including formal fitting and systematic terms. The resulting Hubble constant, based on the use of the Cepheid variables in NGC 4258 to recalibrate the Cepheid distance scale, is H{sub 0} = 72.0 {+-} 3.0 km s{sup -1} Mpc{sup -1}.

  19. [Change in cross-bridge activation rate constant (Kac) after six-minute walk in patients with heart failure].

    PubMed

    Takahashi, M; Takeda, K; Saotome, T; Kobayashi, N; Yagi, S

    1994-01-01

    Cardiac adrenergic activity is increased in patients with congestive heart failure (CHF) and is excessively increased during mild exercise. Changes in cardiac adrenergic activity were examined in normal individuals and patients with CHF before and after mild exercise using the cross-bridge activation rate constant (Ka), which may represent the adrenergic activity related to the working left ventricular myocardium. Ten normal volunteers and 31 patients with stable CHF underwent echocardiography. The left ventricular ejection fraction (LVEF) was measured in all the CHF patients using left ventriculography or radionuclide cineangiography. The patients were classified into two groups: group 1 with an LVEF > or = 50% (n = 16) and group 2 with an LVEF < 50% (n = 15). The cause of CHF was old myocardial infarction in 25 patients and dilated cardiomyopathy in 6. All subjects exercised by walking for 6 min after resting in the supine position for 30 min. The blood pressure, electrocardiogram, phonocardiogram, and M-mode echocardiogram were recorded simultaneously before and after exercise. The values of Ka and Kac (Ka corrected for the individual heart rate) were calculated from the QS2 interval and the heart rate (HR) as follows: Ka = 3/QS2 interval, and Kac = Ka +0.0249 (66-HR). Before exercise, the HR was significantly higher in group 2, but the Kac value showed no significant difference between all three groups. The increase of HR with exercise (delta HR) and the Kac value after exercise were not significantly different between all three groups.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7823284

  20. Time-resolved microrheology of actively remodeling actomyosin networks

    NASA Astrophysics Data System (ADS)

    Silva, Marina Soares e.; Stuhrmann, Björn; Betz, Timo; Koenderink, Gijsje H.

    2014-07-01

    Living cells constitute an extraordinary state of matter since they are inherently out of thermal equilibrium due to internal metabolic processes. Indeed, measurements of particle motion in the cytoplasm of animal cells have revealed clear signatures of nonthermal fluctuations superposed on passive thermal motion. However, it has been difficult to pinpoint the exact molecular origin of this activity. Here, we employ time-resolved microrheology based on particle tracking to measure nonequilibrium fluctuations produced by myosin motor proteins in a minimal model system composed of purified actin filaments and myosin motors. We show that the motors generate spatially heterogeneous contractile fluctuations, which become less frequent with time as a consequence of motor-driven network remodeling. We analyze the particle tracking data on different length scales, combining particle image velocimetry, an ensemble analysis of the particle trajectories, and finally a kymograph analysis of individual particle trajectories to quantify the length and time scales associated with active particle displacements. All analyses show clear signatures of nonequilibrium activity: the particles exhibit random motion with an enhanced amplitude compared to passive samples, and they exhibit sporadic contractile fluctuations with ballistic motion over large (up to 30 μm) distances. This nonequilibrium activity diminishes with sample age, even though the adenosine triphosphate level is held constant. We propose that network coarsening concentrates motors in large clusters and depletes them from the network, thus reducing the occurrence of contractile fluctuations. Our data provide valuable insight into the physical processes underlying stress generation within motor-driven actin networks and the analysis framework may prove useful for future microrheology studies in cells and model organisms.

  1. Correction of dead-time and pile-up in a detector array for constant and rapidly varying counting rates

    NASA Astrophysics Data System (ADS)

    Guerrero, C.; Cano-Ott, D.; Mendoza, E.; Wright, T.

    2015-03-01

    The effect of dead-time and pile-up in counting experiments may become a significant source of uncertainty if not properly taken into account. Although analytical solutions to this problem have been proposed for simple set-ups with one or two detectors, these are limited when it comes to arrays where time correlation between the detector modules is used, and also in situations of variable counting rates. In this paper we describe the dead-time and pile-up corrections applied to the n_TOF Total Absorption Calorimeter (TAC), a 4π γ-ray detector made of 40 BaF2 modules operating at the CERN n_TOF facility. Our method is based on the simulation of the complete signal detection and event reconstruction processes and can be applied as well in the case of rapidly varying counting rates. The method is discussed in detail and then we present its successful application to the particular case of the measurement of 238U(n, γ) reactions with the TAC detector.

  2. REAL TIME DATA FOR REMEDIATION ACTIVITIES [11505

    SciTech Connect

    BROCK CT

    2011-01-13

    Health physicists from the CH2M HILL Plateau Remediation Company collaborated with Berkeley Nucleonics Corporation to modify the SAM 940 isotope identifier instrument to be used for nuclear waste remediation. These modifications coupled with existing capabilities of the SAM 940 have proven to be invaluable during remediation activities, reducing disposal costs by allowing swift remediation of targeted areas that have been identified as having isotopes of concern (IOC), and eliminating multiple visits to sites by declaring an excavation site clear of IOCs before demobilizing from the site. These advantages are enabled by accumulating spectral data for specific isotopes that is nearly 100 percent free of false positives, which are filtered out in 'real time.'

  3. Development of a non-delay line constant fraction discriminator based on the Padé approximant for time-of-flight positron emission tomography scanners

    NASA Astrophysics Data System (ADS)

    Kim, S. Y.; Ko, G. B.; Kwon, S. I.; Lee, J. S.

    2015-01-01

    In positron emission tomography, the constant fraction discriminator (CFD) circuit is used to acquire accurate arrival times for the annihilation photons with minimum sensitivity to time walk. As the number of readout channels increases, it becomes difficult to use conventional CFDs because of the large amount of space required for the delay line part of the circuit. To make the CFD compact, flexible, and easily controllable, a non-delay-line CFD based on the Padé approximant is proposed. The non-delay-line CFD developed in this study is shown to have timing performance that is similar to that of a conventional delay-line-based CFD in terms of the coincidence resolving time of a fast photomultiplier tube detector. This CFD can easily be applied to various positron emission tomography system designs that contain high-density detectors with multi-channel structures.

  4. How Constant Momentum Acceleration Decouples Energy and Space Focusing in Distance-of-Flight and Time-of-Flight Mass Spectrometries

    SciTech Connect

    Dennis, Elise; Gundlach-Graham, Alexander W.; Enke, Chris; Ray, Steven J.; Carado, Anthony J.; Barinaga, Charles J.; Koppenaal, David W.; Hieftje, Gary M.

    2013-05-01

    Time-of-flight (TOF) and distance-of-flight (DOF) mass spectrometers require means for focusing ions at the detector(s) because of initial dispersions of position and energy at the time of their acceleration. Time-of-flight mass spectrometers ordinarily employ constant energy acceleration (CEA), which creates a space-focus plane at which the initial spatial dispersion is corrected. In contrast, constant-momentum acceleration (CMA), in conjunction with an ion mirror, provides focus of the initial energy dispersion at the energy focus time for ions of all m/z at their respective positions along the flight path. With CEA, the initial energy dispersion is not simultaneously correctable as its effect on ion velocity is convoluted with that of the spatial dispersion. The initial spatial dispersion with CMA remains unchanged throughout the field-free region of the flight path, so spatial dispersion can be reduced before acceleration. Improved focus is possible when each dispersion can be addressed independently. With minor modification, a TOF mass spectrometer can be operated in CMA mode by treating the TOF detector as though it were a single element in the array of detectors that would be used in a DOF mass spectrometer. Significant improvement in mass resolution is thereby achieved, albeit over a narrow range of m/z values. In this paper, experimental and theoretical results are presented that illustrate the energy-focusing capabilities of both DOF and TOF mass spectrometry.

  5. Time-resolved optical emission imaging of an atmospheric plasma jet for different electrode positions with a constant electrode gap

    NASA Astrophysics Data System (ADS)

    Maletić, D.; Puač, N.; Selaković, N.; Lazović, S.; Malović, G.; Đorđević, A.; Petrović, Z. Lj

    2015-04-01

    The aim of this paper is to determine the influence of the position of the electrodes on the range of a plasma jet, for specific experimental conditions, by using time-resolved optical emission spectroscopy. The optimal position of the electrodes is determined for a fixed gas flow rate and applied excitation voltage. We characterize the helium plasma jet for different distances from the end of the glass tube, showing detailed results for four different electrode positions from the jet nozzle (7, 15, 30 and 50 mm). It was found that at the distance of 15 mm, the length of the plasma jet is at its maximum. The highest speeds of the plasma package travelling outside the glass tube of the atmospheric plasma jet are obtained for the same electrode configuration (15 mm from the jet nozzle). With the electrodes positioned at smaller distances from the nozzle, the plasma plume was much shorter, and at the larger distances the plasma did not even leave the glass tube.

  6. New definitions of pointing stability - ac and dc effects. [constant and time-dependent pointing error effects on image sensor performance

    NASA Technical Reports Server (NTRS)

    Lucke, Robert L.; Sirlin, Samuel W.; San Martin, A. M.

    1992-01-01

    For most imaging sensors, a constant (dc) pointing error is unimportant (unless large), but time-dependent (ac) errors degrade performance by either distorting or smearing the image. When properly quantified, the separation of the root-mean-square effects of random line-of-sight motions into dc and ac components can be used to obtain the minimum necessary line-of-sight stability specifications. The relation between stability requirements and sensor resolution is discussed, with a view to improving communication between the data analyst and the control systems engineer.

  7. A time-based potential step analysis of electrochemical impedance incorporating a constant phase element: a study of commercially pure titanium in phosphate buffered saline.

    PubMed

    Ehrensberger, Mark T; Gilbert, Jeremy L

    2010-05-01

    The measurement of electrochemical impedance is a valuable tool to assess the electrochemical environment that exists at the surface of metallic biomaterials. This article describes the development and validation of a new technique, potential step impedance analysis (PSIA), to assess the electrochemical impedance of materials whose interface with solution can be modeled as a simplified Randles circuit that is modified with a constant phase element. PSIA is based upon applying a step change in voltage to a working electrode and analyzing the subsequent current transient response in a combined time and frequency domain technique. The solution resistance, polarization resistance, and interfacial capacitance are found directly in the time domain. The experimental current transient is numerically transformed to the frequency domain to determine the constant phase exponent, alpha. This combined time and frequency approach was tested using current transients generated from computer simulations, from resistor-capacitor breadboard circuits, and from commercially pure titanium samples immersed in phosphate buffered saline and polarized at -800 mV or +1000 mV versus Ag/AgCl. It was shown that PSIA calculates equivalent admittance and impedance behavior over this range of potentials when compared to standard electrochemical impedance spectroscopy. This current transient approach characterizes the frequency response of the system without the need for expensive frequency response analyzers or software.

  8. Variable versus constant power strategies during cycling time-trials: prediction of time savings using an up-to-date mathematical model.

    PubMed

    Atkinson, G; Peacock, O; Passfield, L

    2007-07-01

    Swain (1997) employed the mathematical model of Di Prampero et al. (1979) to predict that, for cycling time-trials, the optimal pacing strategy is to vary power in parallel with the changes experienced in gradient and wind speed. We used a more up-to-date mathematical model with validated coefficients (Martin et al., 1998) to quantify the time savings that would result from such optimization of pacing strategy. A hypothetical cyclist (mass = 70 kg) and bicycle (mass = 10 kg) were studied under varying hypothetical wind velocities (-10 to 10 m x s(-1)), gradients (-10 to 10%), and pacing strategies. Mean rider power outputs of 164, 289, and 394 W were chosen to mirror baseline performances studied previously. The three race scenarios were: (i) a 10-km time-trial with alternating 1-km sections of 10% and -10% gradient; (ii) a 40-km time-trial with alternating 5-km sections of 4.4 and -4.4 m x s(-1) wind (Swain, 1997); and (iii) the 40-km time-trial delimited by Jeukendrup and Martin (2001). Varying a mean power of 289 W by +/- 10% during Swain's (1997) hilly and windy courses resulted in time savings of 126 and 51 s, respectively. Time savings for most race scenarios were greater than those suggested by Swain (1997). For a mean power of 289 W over the "standard" 40-km time-trial, a time saving of 26 s was observed with a power variability of 10%. The largest time savings were found for the hypothetical riders with the lowest mean power output who could vary power to the greatest extent. Our findings confirm that time savings are possible in cycling time-trials if the rider varies power in parallel with hill gradient and wind direction. With a more recent mathematical model, we found slightly greater time savings than those reported by Swain (1997). These time savings compared favourably with the predicted benefits of interventions such as altitude training or ingestion of carbohydrate-electrolyte drinks. Nevertheless, the extent to which such power output variations

  9. A Time Scheduling Model of Logistics Service Supply Chain Based on the Customer Order Decoupling Point: A Perspective from the Constant Service Operation Time

    PubMed Central

    Yang, Yi; Xu, Haitao; Liu, Xiaoyan; Wang, Yijia; Liang, Zhicheng

    2014-01-01

    In mass customization logistics service, reasonable scheduling of the logistics service supply chain (LSSC), especially time scheduling, is benefit to increase its competitiveness. Therefore, the effect of a customer order decoupling point (CODP) on the time scheduling performance should be considered. To minimize the total order operation cost of the LSSC, minimize the difference between the expected and actual time of completing the service orders, and maximize the satisfaction of functional logistics service providers, this study establishes an LSSC time scheduling model based on the CODP. Matlab 7.8 software is used in the numerical analysis for a specific example. Results show that the order completion time of the LSSC can be delayed or be ahead of schedule but cannot be infinitely advanced or infinitely delayed. Obtaining the optimal comprehensive performance can be effective if the expected order completion time is appropriately delayed. The increase in supply chain comprehensive performance caused by the increase in the relationship coefficient of logistics service integrator (LSI) is limited. The relative concern degree of LSI on cost and service delivery punctuality leads to not only changes in CODP but also to those in the scheduling performance of the LSSC. PMID:24715818

  10. A time scheduling model of logistics service supply chain based on the customer order decoupling point: a perspective from the constant service operation time.

    PubMed

    Liu, Weihua; Yang, Yi; Xu, Haitao; Liu, Xiaoyan; Wang, Yijia; Liang, Zhicheng

    2014-01-01

    In mass customization logistics service, reasonable scheduling of the logistics service supply chain (LSSC), especially time scheduling, is benefit to increase its competitiveness. Therefore, the effect of a customer order decoupling point (CODP) on the time scheduling performance should be considered. To minimize the total order operation cost of the LSSC, minimize the difference between the expected and actual time of completing the service orders, and maximize the satisfaction of functional logistics service providers, this study establishes an LSSC time scheduling model based on the CODP. Matlab 7.8 software is used in the numerical analysis for a specific example. Results show that the order completion time of the LSSC can be delayed or be ahead of schedule but cannot be infinitely advanced or infinitely delayed. Obtaining the optimal comprehensive performance can be effective if the expected order completion time is appropriately delayed. The increase in supply chain comprehensive performance caused by the increase in the relationship coefficient of logistics service integrator (LSI) is limited. The relative concern degree of LSI on cost and service delivery punctuality leads to not only changes in CODP but also to those in the scheduling performance of the LSSC.

  11. A time scheduling model of logistics service supply chain based on the customer order decoupling point: a perspective from the constant service operation time.

    PubMed

    Liu, Weihua; Yang, Yi; Xu, Haitao; Liu, Xiaoyan; Wang, Yijia; Liang, Zhicheng

    2014-01-01

    In mass customization logistics service, reasonable scheduling of the logistics service supply chain (LSSC), especially time scheduling, is benefit to increase its competitiveness. Therefore, the effect of a customer order decoupling point (CODP) on the time scheduling performance should be considered. To minimize the total order operation cost of the LSSC, minimize the difference between the expected and actual time of completing the service orders, and maximize the satisfaction of functional logistics service providers, this study establishes an LSSC time scheduling model based on the CODP. Matlab 7.8 software is used in the numerical analysis for a specific example. Results show that the order completion time of the LSSC can be delayed or be ahead of schedule but cannot be infinitely advanced or infinitely delayed. Obtaining the optimal comprehensive performance can be effective if the expected order completion time is appropriately delayed. The increase in supply chain comprehensive performance caused by the increase in the relationship coefficient of logistics service integrator (LSI) is limited. The relative concern degree of LSI on cost and service delivery punctuality leads to not only changes in CODP but also to those in the scheduling performance of the LSSC. PMID:24715818

  12. Measurement of homonuclear magnetic dipole-dipole interactions in multiple 1/2-spin systems using constant-time DQ-DRENAR NMR

    NASA Astrophysics Data System (ADS)

    Ren, Jinjun; Eckert, Hellmut

    2015-11-01

    A new pulse sequence entitled DQ-DRENAR (Double-Quantum based Dipolar Recoupling Effects Nuclear Alignment Reduction) was recently described for the quantitative measurement of magnetic dipole-dipole interactions in homonuclear spin-1/2 systems involving multiple nuclei. As described in the present manuscript, the efficiency and performance of this sequence can be significantly improved, if the measurement is done in the constant-time mode. We describe both the theoretical analysis of this method and its experimental validation of a number of crystalline model compounds, considering both symmetry-based and back-to-back (BABA) DQ-coherence excitation schemes. Based on the combination of theoretical analysis and experimental results we discuss the effect of experimental parameters such as the chemical shift anisotropy (CSA), the spinning rate, and the radio frequency field inhomogeneity upon its performance. Our results indicate that constant-time (CT-) DRENAR is a method of high efficiency and accuracy for compounds with multiple homonuclear spin systems with particular promise for the analysis of stronger-coupled and short T2 spin systems.

  13. Sub-nanosecond time-resolved ambient-pressure X-ray photoelectron spectroscopy setup for pulsed and constant wave X-ray light sources.

    PubMed

    Shavorskiy, Andrey; Neppl, Stefan; Slaughter, Daniel S; Cryan, James P; Siefermann, Katrin R; Weise, Fabian; Lin, Ming-Fu; Bacellar, Camila; Ziemkiewicz, Michael P; Zegkinoglou, Ioannis; Fraund, Matthew W; Khurmi, Champak; Hertlein, Marcus P; Wright, Travis W; Huse, Nils; Schoenlein, Robert W; Tyliszczak, Tolek; Coslovich, Giacomo; Robinson, Joseph; Kaindl, Robert A; Rude, Bruce S; Ölsner, Andreas; Mähl, Sven; Bluhm, Hendrik; Gessner, Oliver

    2014-09-01

    An apparatus for sub-nanosecond time-resolved ambient-pressure X-ray photoelectron spectroscopy studies with pulsed and constant wave X-ray light sources is presented. A differentially pumped hemispherical electron analyzer is equipped with a delay-line detector that simultaneously records the position and arrival time of every single electron at the exit aperture of the hemisphere with ~0.1 mm spatial resolution and ~150 ps temporal accuracy. The kinetic energies of the photoelectrons are encoded in the hit positions along the dispersive axis of the two-dimensional detector. Pump-probe time-delays are provided by the electron arrival times relative to the pump pulse timing. An average time-resolution of (780 ± 20) ps (FWHM) is demonstrated for a hemisphere pass energy E(p) = 150 eV and an electron kinetic energy range KE = 503-508 eV. The time-resolution of the setup is limited by the electron time-of-flight (TOF) spread related to the electron trajectory distribution within the analyzer hemisphere and within the electrostatic lens system that images the interaction volume onto the hemisphere entrance slit. The TOF spread for electrons with KE = 430 eV varies between ~9 ns at a pass energy of 50 eV and ~1 ns at pass energies between 200 eV and 400 eV. The correlation between the retarding ratio and the TOF spread is evaluated by means of both analytical descriptions of the electron trajectories within the analyzer hemisphere and computer simulations of the entire trajectories including the electrostatic lens system. In agreement with previous studies, we find that the by far dominant contribution to the TOF spread is acquired within the hemisphere. However, both experiment and computer simulations show that the lens system indirectly affects the time resolution of the setup to a significant extent by inducing a strong dependence of the angular spread of electron trajectories entering the hemisphere on the retarding ratio. The scaling of the angular spread with

  14. Sub-nanosecond time-resolved ambient-pressure X-ray photoelectron spectroscopy setup for pulsed and constant wave X-ray light sources.

    PubMed

    Shavorskiy, Andrey; Neppl, Stefan; Slaughter, Daniel S; Cryan, James P; Siefermann, Katrin R; Weise, Fabian; Lin, Ming-Fu; Bacellar, Camila; Ziemkiewicz, Michael P; Zegkinoglou, Ioannis; Fraund, Matthew W; Khurmi, Champak; Hertlein, Marcus P; Wright, Travis W; Huse, Nils; Schoenlein, Robert W; Tyliszczak, Tolek; Coslovich, Giacomo; Robinson, Joseph; Kaindl, Robert A; Rude, Bruce S; Ölsner, Andreas; Mähl, Sven; Bluhm, Hendrik; Gessner, Oliver

    2014-09-01

    An apparatus for sub-nanosecond time-resolved ambient-pressure X-ray photoelectron spectroscopy studies with pulsed and constant wave X-ray light sources is presented. A differentially pumped hemispherical electron analyzer is equipped with a delay-line detector that simultaneously records the position and arrival time of every single electron at the exit aperture of the hemisphere with ~0.1 mm spatial resolution and ~150 ps temporal accuracy. The kinetic energies of the photoelectrons are encoded in the hit positions along the dispersive axis of the two-dimensional detector. Pump-probe time-delays are provided by the electron arrival times relative to the pump pulse timing. An average time-resolution of (780 ± 20) ps (FWHM) is demonstrated for a hemisphere pass energy E(p) = 150 eV and an electron kinetic energy range KE = 503-508 eV. The time-resolution of the setup is limited by the electron time-of-flight (TOF) spread related to the electron trajectory distribution within the analyzer hemisphere and within the electrostatic lens system that images the interaction volume onto the hemisphere entrance slit. The TOF spread for electrons with KE = 430 eV varies between ~9 ns at a pass energy of 50 eV and ~1 ns at pass energies between 200 eV and 400 eV. The correlation between the retarding ratio and the TOF spread is evaluated by means of both analytical descriptions of the electron trajectories within the analyzer hemisphere and computer simulations of the entire trajectories including the electrostatic lens system. In agreement with previous studies, we find that the by far dominant contribution to the TOF spread is acquired within the hemisphere. However, both experiment and computer simulations show that the lens system indirectly affects the time resolution of the setup to a significant extent by inducing a strong dependence of the angular spread of electron trajectories entering the hemisphere on the retarding ratio. The scaling of the angular spread with

  15. Time-dependent changes in skeletal response to teriparatide: Escalating versus constant dose teriparatide (PTH 1–34) in osteoporotic women

    PubMed Central

    Yu, Elaine W.; Neer, Robert M.; Lee, Hang; Wyland, Jason J.; de la Paz, Amanda V.; Davis, Melissa C.; Okazaki, Makoto; Finkelstein, Joel S.

    2010-01-01

    Once-daily injections of teriparatide initially increase biochemical markers of bone formation and resorption, but markers peak after 6–12 months and then decline despite continued treatment. We sought to determine whether increasing teriparatide doses in a stepwise fashion could prolong skeletal responsiveness. We randomized 52 postmenopausal women with low spine and/or hip bone mineral density (BMD) to either a constant or an escalating subcutaneous teriparatide dose (30 mcg daily for 18 months or 20 mcg daily for 6 months, then 30 mcg daily for 6 months, then 40 mcg daily for 6 months). Serum procollagen I N-terminal propeptide, osteocalcin, and C-terminal telopeptide of type I collagen were assessed frequently. BMD of the spine, hip, radius, and total body was measured every 6 months. Acute changes in urinary cyclic AMP in response to teriparatide were examined in a subset of women in the constant dose group. All bone markers differed significantly between the two treatment groups. During the final six months, bone markers declined in the constant dose group but remained stable or increased in the escalating dose group (all markers, p<0.017). Nonetheless, mean area under the curve did not differ between treatments for any bone marker, and BMD increases were equivalent in both treatment groups. Acute renal response to teriparatide, as assessed by urinary cyclic AMP, did not change over 18 months of teriparatide administration. In conclusion, stepwise increases in teriparatide prevented the decline in bone turnover markers that is observed with chronic administration without altering BMD increases. The time-dependent waning of the response to teriparatide appears to be bone-specific. PMID:21111078

  16. Subependymal giant cell astrocytoma: a lesion with activated mTOR pathway and constant expression of glutamine synthetase.

    PubMed

    Buccoliero, Anna Maria; Caporalini, Chiara; Giordano, Flavio; Mussa, Federico; Scagnet, Mirko; Moscardi, Selene; Baroni, Gianna; Genitori, Lorenzo; Taddei, Gian Luigi

    2016-01-01

    Subependymal giant-cell astrocytoma (SEGA) is a rare tumor associated with tuberous sclerosis complex (TSC). TSC mainly involves the central nervous system (CNS) where SEGA, subependymal nodules, and cortical tubers may be present. First studies suggested the astrocytic nature of SEGA while successive studies demonstrated the mixed glio-neuronal nature. There are similarities between TSC-associated CNS lesions and type IIb focal cortical dysplasia (FCD). In all these pathologies, mammalian target of rapamycin (mTOR) pathway activation has been demonstrated. Recent data evidenced that balloon cells in FCD IIb express glutamine synthetase (GS). GS is involved in the clearance of glutamate. Cells expressing GS might exert an antiepileptic role. We evaluated by immunohistochemistry the glial fibrillary acidic protein (GFAP), neurofilaments (NF), and GS expression and the mTOR status (mTOR and phosphorylated ribosomal protein S6) in 16 SEGAs and 2 cortical tubers. Our purpose was to emphasize the mixed nature of SEGA and to further investigate the similarities between TSC-related CNS lesions (in particular SEGA) and FCD IIb. We confirm the glio-neuronal nature and the common activation of the mTOR pathway in SEGAs. In addition, we report for the first time that these tumors, analogously to FCD IIb, commonly express GS. Notably, the expression of mTOR, phosphorylated ribosomal protein S6, and GS was restricted to gemistocytic-like GFAP-negative cells. GS expression and mTOR pathway activation were also documented in cortical tubers. Further studies are necessary to understand the significance of GS expression in SEGAs as well as in cortical tubers. PMID:27390104

  17. Subependymal giant cell astrocytoma: a lesion with activated mTOR pathway and constant expression of glutamine synthetase.

    PubMed

    Buccoliero, Anna Maria; Caporalini, Chiara; Giordano, Flavio; Mussa, Federico; Scagnet, Mirko; Moscardi, Selene; Baroni, Gianna; Genitori, Lorenzo; Taddei, Gian Luigi

    2016-01-01

    Subependymal giant-cell astrocytoma (SEGA) is a rare tumor associated with tuberous sclerosis complex (TSC). TSC mainly involves the central nervous system (CNS) where SEGA, subependymal nodules, and cortical tubers may be present. First studies suggested the astrocytic nature of SEGA while successive studies demonstrated the mixed glio-neuronal nature. There are similarities between TSC-associated CNS lesions and type IIb focal cortical dysplasia (FCD). In all these pathologies, mammalian target of rapamycin (mTOR) pathway activation has been demonstrated. Recent data evidenced that balloon cells in FCD IIb express glutamine synthetase (GS). GS is involved in the clearance of glutamate. Cells expressing GS might exert an antiepileptic role. We evaluated by immunohistochemistry the glial fibrillary acidic protein (GFAP), neurofilaments (NF), and GS expression and the mTOR status (mTOR and phosphorylated ribosomal protein S6) in 16 SEGAs and 2 cortical tubers. Our purpose was to emphasize the mixed nature of SEGA and to further investigate the similarities between TSC-related CNS lesions (in particular SEGA) and FCD IIb. We confirm the glio-neuronal nature and the common activation of the mTOR pathway in SEGAs. In addition, we report for the first time that these tumors, analogously to FCD IIb, commonly express GS. Notably, the expression of mTOR, phosphorylated ribosomal protein S6, and GS was restricted to gemistocytic-like GFAP-negative cells. GS expression and mTOR pathway activation were also documented in cortical tubers. Further studies are necessary to understand the significance of GS expression in SEGAs as well as in cortical tubers.

  18. Sieve Estimation of Constant and Time-Varying Coefficients in Nonlinear Ordinary Differential Equation Models by Considering Both Numerical Error and Measurement Error

    PubMed Central

    Xue, Hongqi; Miao, Hongyu; Wu, Hulin

    2010-01-01

    This article considers estimation of constant and time-varying coefficients in nonlinear ordinary differential equation (ODE) models where analytic closed-form solutions are not available. The numerical solution-based nonlinear least squares (NLS) estimator is investigated in this study. A numerical algorithm such as the Runge–Kutta method is used to approximate the ODE solution. The asymptotic properties are established for the proposed estimators considering both numerical error and measurement error. The B-spline is used to approximate the time-varying coefficients, and the corresponding asymptotic theories in this case are investigated under the framework of the sieve approach. Our results show that if the maximum step size of the p-order numerical algorithm goes to zero at a rate faster than n−1/(p∧4), the numerical error is negligible compared to the measurement error. This result provides a theoretical guidance in selection of the step size for numerical evaluations of ODEs. Moreover, we have shown that the numerical solution-based NLS estimator and the sieve NLS estimator are strongly consistent. The sieve estimator of constant parameters is asymptotically normal with the same asymptotic co-variance as that of the case where the true ODE solution is exactly known, while the estimator of the time-varying parameter has the optimal convergence rate under some regularity conditions. The theoretical results are also developed for the case when the step size of the ODE numerical solver does not go to zero fast enough or the numerical error is comparable to the measurement error. We illustrate our approach with both simulation studies and clinical data on HIV viral dynamics. PMID:21132064

  19. Time since death and decay rate constants of Norway spruce and European larch deadwood in subalpine forests determined using dendrochronology and radiocarbon dating

    NASA Astrophysics Data System (ADS)

    Petrillo, M.; Cherubini, P.; Fravolini, G.; Ascher, J.; Schärer, M.; Synal, H.-A.; Bertoldi, D.; Camin, F.; Larcher, R.; Egli, M.

    2015-09-01

    Due to the large size and highly heterogeneous spatial distribution of deadwood, the time scales involved in the coarse woody debris (CWD) decay of Picea abies (L.) Karst. and Larix decidua Mill. in Alpine forests have been poorly investigated and are largely unknown. We investigated the CWD decay dynamics in an Alpine valley in Italy using the five-decay class system commonly employed for forest surveys, based on a macromorphological and visual assessment. For the decay classes 1 to 3, most of the dendrochronological samples were cross-dated to assess the time that had elapsed since tree death, but for decay classes 4 and 5 (poorly preserved tree rings) and some others not having enough tree rings, radiocarbon dating was used. In addition, density, cellulose and lignin data were measured for the dated CWD. The decay rate constants for spruce and larch were estimated on the basis of the density loss using a single negative exponential model. In the decay classes 1 to 3, the ages of the CWD were similar varying between 1 and 54 years for spruce and 3 and 40 years for larch with no significant differences between the classes; classes 1-3 are therefore not indicative for deadwood age. We found, however, distinct tree species-specific differences in decay classes 4 and 5, with larch CWD reaching an average age of 210 years in class 5 and spruce only 77 years. The mean CWD rate constants were 0.012 to 0.018 yr-1 for spruce and 0.005 to 0.012 yr-1 for larch. Cellulose and lignin time trends half-lives (using a multiple-exponential model) could be derived on the basis of the ages of the CWD. The half-lives for cellulose were 21 yr for spruce and 50 yr for larch. The half-life of lignin is considerably higher and may be more than 100 years in larch CWD.

  20. Active euthanasia--time for a decision.

    PubMed Central

    Jeffrey, D

    1994-01-01

    There has been renewed interest in the moral arguments surrounding euthanasia. Some patients are now apprehensive of advanced medical technology which they fear may result in a prolonged and undignified death. In the current situation of scarce resources for health care, both patients and doctors could be coerced into considering active euthanasia if it was legally available. In this paper it is argued that doctors now need to make a clear statement rejecting active euthanasia but affirming that in certain cases passive euthanasia, or letting die, may be morally justifiable. PMID:8204323

  1. Compassion is a constant.

    PubMed

    Scott, Tricia

    2015-11-01

    Compassion is a powerful word that describes an intense feeling of commiseration and a desire to help those struck by misfortune. Most people know intuitively how and when to offer compassion to relieve another person's suffering. In health care, compassion is a constant; it cannot be rationed because emergency nurses have limited time or resources to manage increasing demands.

  2. Compassion is a constant.

    PubMed

    Scott, Tricia

    2015-11-01

    Compassion is a powerful word that describes an intense feeling of commiseration and a desire to help those struck by misfortune. Most people know intuitively how and when to offer compassion to relieve another person's suffering. In health care, compassion is a constant; it cannot be rationed because emergency nurses have limited time or resources to manage increasing demands. PMID:26542898

  3. Haida Story Telling Time with Activity Folder.

    ERIC Educational Resources Information Center

    Cogo, Robert

    One in a series of curriculum materials on Southeast Alaska Natives, this booklet contains seven myths and legends from the Haida oral tradition, each accompanied by discussion questions and suggested learning activities. Intended for use in the intermediate grades, the stories are two to four pages long with many Haida words included in the text…

  4. Comparison of constant and time-variant optimal forcing approaches in El Niño simulations by using the Zebiak-Cane model

    NASA Astrophysics Data System (ADS)

    Tian, Ben; Duan, Wansuo

    2016-06-01

    Model errors offset by constant and time-variant optimal forcing vector approaches (termed COF and OFV, respectively) are analyzed within the framework of El Ni˜no simulations. Applying the COF and OFV approaches to the well-known Zebiak-Cane model, we re-simulate the 1997 and 2004 El Ni˜no events, both of which were poorly degraded by a certain amount of model error when the initial anomalies were generated by coupling the observed wind forcing to an ocean component. It is found that the Zebiak-Cane model with the COF approach roughly reproduced the 1997 El Ni˜no, but the 2004 El Ni˜no simulated by this approach defied an ENSO classification, i.e., it was hardly distinguishable as CP-El Ni˜no or EP-El Ni˜no. In both El Ni˜no simulations, substituting the COF with the OFV improved the fit between the simulations and observations because the OFV better manages the time-variant errors in the model. Furthermore, the OFV approach effectively corrected the modeled El Ni˜no events even when the observational data (and hence the computational time) were reduced. Such a cost-effective offset of model errors suggests a role for the OFV approach in complicated CGCMs.

  5. Time since death and decay rate constants of Norway spruce and European larch deadwood in subalpine forests determined using dendrochronology and radiocarbon dating

    NASA Astrophysics Data System (ADS)

    Petrillo, Marta; Cherubini, Paolo; Fravolini, Giulia; Marchetti, Marco; Ascher-Jenull, Judith; Schärer, Michael; Synal, Hans-Arno; Bertoldi, Daniela; Camin, Federica; Larcher, Roberto; Egli, Markus

    2016-03-01

    Due to the large size (e.g. sections of tree trunks) and highly heterogeneous spatial distribution of deadwood, the timescales involved in the coarse woody debris (CWD) decay of Picea abies (L.) Karst. and Larix decidua Mill. in Alpine forests are largely unknown. We investigated the CWD decay dynamics in an Alpine valley in Italy using the chronosequence approach and the five-decay class system that is based on a macromorphological assessment. For the decay classes 1-3, most of the dendrochronological samples were cross-dated to assess the time that had elapsed since tree death, but for decay classes 4 and 5 (poorly preserved tree rings) radiocarbon dating was used. In addition, density, cellulose, and lignin data were measured for the dated CWD. The decay rate constants for spruce and larch were estimated on the basis of the density loss using a single negative exponential model, a regression approach, and the stage-based matrix model. In the decay classes 1-3, the ages of the CWD were similar and varied between 1 and 54 years for spruce and 3 and 40 years for larch, with no significant differences between the classes; classes 1-3 are therefore not indicative of deadwood age. This seems to be due to a time lag between the death of a standing tree and its contact with the soil. We found distinct tree-species-specific differences in decay classes 4 and 5, with larch CWD reaching an average age of 210 years in class 5 and spruce only 77 years. The mean CWD rate constants were estimated to be in the range 0.018 to 0.022 y-1 for spruce and to about 0.012 y-1 for larch. Snapshot sampling (chronosequences) may overestimate the age and mean residence time of CWD. No sampling bias was, however, detectable using the stage-based matrix model. Cellulose and lignin time trends could be derived on the basis of the ages of the CWD. The half-lives for cellulose were 21 years for spruce and 50 years for larch. The half-life of lignin is considerably higher and may be more than

  6. Time perspective and physical activity among central Appalachian adolescents.

    PubMed

    Gulley, Tauna

    2013-04-01

    Time perspective is a cultural behavioral concept that reflects individuals' orientations or attitudes toward the past, present, or future. Individuals' time perspectives influence their choices regarding daily activities. Time perspective is an important consideration when teaching adolescents about the importance of being physically active. However, little is known about the relationship between time perspective and physical activity among adolescents. The purpose of this study was to determine the time perspective of central Appalachian adolescents and explore the relationship between time perspective and physical activity. This study was guided by The theory of planned behavior (TPB). One hundred and ninety-three students completed surveys to examine time perspective and physical activity behaviors. Data were collected in one school. Results of this study can inform school nurses and high school guidance counselors about the importance of promoting a future-oriented time perspective to improve physical activity and educational outcomes.

  7. A direct comparison of U.S. Environmental Protection Agency's method 304B and batch tests for determining activated-sludge biodegradation rate constants for volatile organic compounds

    SciTech Connect

    Cano, M.L.; Wilcox, M.E.; Compernolle, R. van

    1999-12-01

    Biodegradation rate constants for volatile organic compounds (VOCs) in activated-sludge systems are needed to quantify emissions. One current US environmental Protection Agency method for determining a biodegradation rate constant is Method 304B. In this approach, a specific activated-sludge unit is simulated by a continuous biological treatment system with a sealed headspace. Batch experiments, however, can be alternatives to Method 304B. Two of these batch methods are the batch test that uses oxygen addition (BOX) and the serum bottle test (SBT). In this study, Method 304B was directly compared to BOX and SBT experiments. A pilot-scale laboratory reactor was constructed to serve as the Method 304B unit. Biomass from the unit was also used to conduct BOX and modified SBT experiments (modification involved use of a sealed draft-tube reactor with a headspace recirculation pump instead of a serum bottle) for 1,2-dichloroethane, diisopropyl ether, methyl tertiary butyl ether, and toluene. Three experimental runs--each consisting of one Method 304B experiment, one BOX experiment, and one modified SBT experiment--were completed. The BOX and SBT data for each run were analyzed using a Monod model, and best-fit biodegradation kinetic parameters were determined for each experiment, including a first-order biodegradation rate constant (K{sub 1}). Experimental results suggest that for readily biodegradable VOCs the two batch techniques can provide improved means of determining biodegradation rate constants compared with Method 304B. In particular, these batch techniques avoid the Method 304B problem associated with steady-state effluent concentrations below analytical detection limits. However, experimental results also suggest that the two batch techniques should not be used to determine biodegradation rate constants for slowly degraded VOCs (i.e., K{sub 1} {lt} 0.1 L/g VSS-h).

  8. In situ real-time monitoring of profile evolution during plasma etching of mesoporous low-dielectric-constant SiO{sub 2}

    SciTech Connect

    Gerung, Henry; Brinker, C. Jeffrey; Brueck, Steven R.J.; Han, Sang M.

    2005-03-01

    We have employed attenuated total reflection Fourier transforms infrared spectroscopy (ATR-FTIRS) to monitor the profile evolution of patterned mesoporous, low-dielectric-constant SiO{sub 2} films in situ and in real time during plasma etching. A stack of patterned photoresist, anti-reflective coating, and mesoporous SiO{sub 2} is etched in an inductively coupled plasma reactor, using CHF{sub 3} and Ar. During etching, the IR absorbance of Si-O-Si stretching modes near 1080 cm{sup -1} decreases, and the rate of decrease in Si-O-Si absorbance translates to the SiO{sub 2} removal rate. When corrected for the exponentially decaying evanescent electric field, the removal rate helps monitor the profile evolution and predict the final etch profile. The predicted profiles are in excellent agreement with the cross-sectional images taken by scanning electron microscopy. In a similar approach, we calculate the absolute total number of C-F bonds in the sidewall passivation and observe its formation rate as a function of time. Assuming that the thickness of the sidewall passivation tapers down towards the trench bottom, we deduce that C-F formation occurs mostly in the final stage of etching when the trench bottom meets the Ge ATR crystal and that a critical amount of C-F buildup is necessary to maintain the anisotropic etch profile.

  9. Rate constant for the reaction of OH with methyl iodide, a re-determination by flash photolysis of water vapour and time resolved resonance fluorescence of OH

    NASA Astrophysics Data System (ADS)

    Zhang, Shaoliang; Strekowski, Rafal; Zetzsch, Cornelius

    2010-05-01

    Methyl iodide is a major source gas for atmospheric iodine, and it is mainly emitted from the ocean. Aqueous-phase reactions, such as hydrolysis and exchange reactions with chloride control its emissions to the atmosphere, where its lifetime is limited to less than a week, mainly by photolysis. A minor contribution to the loss processes in the troposphere is the gas-phase reaction with OH radicals, that has been investigated by several authors. On the other hand, this reaction turned out to be uncertain in spite of interest in nuclear safety after the International Phebus Fission Product programme, initiated in 1988. Some of the most important observed phenomena with regard to the chemistry of iodine were not predicted, clearly showing the need for carrying out rate constant determinations for the reactions of I2 and CH3I with OH, which is a major oxidant product from the air radiolysis under accident conditions. We have measured the rate constant for the reaction OH + CH3I - H2O + CH2I in He at 260 mbar in the temperature range from 298 to 362 K. OH radicals were produced by flash photolysis of H2O in the vacuum-UV at wavelengths > 115 nm using a Xe flash lamp with a MgF2 window. Time profiles of OH radicals are monitored by resonance fluorescence of the A2 Σ - X2 Π transition at 308 nm, induced by the emission from a microwave discharge of a flow of He and H2O, a few Torr each. The signal is monitored by photon counting and multichannel scaling, collecting the counts from 50 flashes each, obtaind by pulsed photolysis of various mixtures of H2O and CH3I under slow-flow conditions. Decays of OH in the presence of CH3I are observed to be exponential, and the decay rates are found to be linearly dependent on the concentration of CH3I. Rate constants, k ± 2σ (in units of 10-14 cm3 s-1) of 4.14±0.20, 6.33±0.68, 7.31±1.18 and 8.24±1.60 at 298, 326, 352 and 362 K, respectively, are obtained from linear regressions and lead to an Arrhenius expression of k = 1.5

  10. How Young Children Spend Their Time: Television and Other Activities.

    ERIC Educational Resources Information Center

    Huston, Aletha C.; Wright, John C.; Marquis, Janet; Green, Samuel B.

    1999-01-01

    Examined television viewing over three years among two cohorts of 2- and 4-year olds. Found that viewing declined with age. With age, time in reading and educational activities increased on weekdays but declined on weekends, and sex differences in time-use patterns increased. Increased time in educational activities, social interaction, and video…

  11. How constant momentum acceleration decouples energy and space focusing in distance-of-flight and time-of-flight mass spectrometries.

    PubMed

    Dennis, Elise A; Gundlach-Graham, Alexander W; Enke, Christie G; Ray, Steven J; Carado, Anthony J; Barinaga, Charles J; Koppenaal, David W; Hieftje, Gary M

    2013-05-01

    Resolution in time-of-flight mass spectrometry (TOFMS) is ordinarily limited by the initial energy and space distributions within an instrument's acceleration region and by the length of the field-free flight zone. With gaseous ion sources, these distributions lead to systematic flight-time errors that cannot be simultaneously corrected with conventional static-field ion-focusing devices (i.e., an ion mirror). It is known that initial energy and space distributions produce non-linearly correlated errors in both ion velocity and exit time from the acceleration region. Here we reinvestigate an old acceleration technique, constant-momentum acceleration (CMA), to decouple the effects of initial energy and space distributions. In CMA, only initial ion energies (and not their positions) affect the velocity ions gain. Therefore, with CMA, the spatial distribution within the acceleration region can be manipulated without creating ion-velocity error. The velocity differences caused by a spread in initial ion energy can be corrected with an ion mirror. We discuss here the use of CMA and independent focusing of energy and space distributions for both distance-of-flight mass spectrometry (DOFMS) and TOFMS. Performance characteristics of our CMA-DOFMS and CMA-TOFMS instrument, fitted with a glow-discharge ionization source, are described. In CMA-DOFMS, resolving powers (FWHM) of greater than 1000 are achieved for atomic ions with a flight length of 285 mm. In CMA-TOFMS, only ions over a narrow range of m/z values can be energy-focused; however, the technique offers improved resolution for these focused ions, with resolving powers of greater than 2000 for a separation distance of 350 mm.

  12. Transglutaminase 2 gene ablation protects against renal ischemic injury by blocking constant NF-{kappa}B activation

    SciTech Connect

    Kim, Dae-Seok; Kim, Bora; Tahk, Hongmin; Kim, Dong-Hyun; Ahn, Eu-Ree; Choi, Changsun; Jeon, Yoon; Park, Seo Young; Lee, Ho; Oh, Seung Hyun; Kim, Soo-Youl

    2010-12-17

    Research highlights: {yields} No acute renal tubular necrotic lesions were found in TGase2{sup -/-} mice with ischemic kidney injury. {yields} NF-{kappa}B activation is reduced in TGase2{sup -/-} mice with ischemic kidney injury. {yields} Hypoxic stress did not increase NF-{kappa}B activity in MEFs from TGase2{sup -/-} mice. {yields} COX-2 induction is suppressed in TGase2{sup -/-} mice with ischemic kidney injury. -- Abstract: Transglutaminase 2 knockout (TGase2{sup -/-}) mice show significantly reduced inflammation with decreased myofibroblasts in a unilateral ureteral obstruction (UUO) model, but the mechanism remains to be clarified. Nuclear factor-{kappa}B (NF-{kappa}B) activation plays a major role in the progression of inflammation in an obstructive nephropathy model. However, the key factors extending the duration of NF-{kappa}B activation in UUO are not known. In several inflammatory diseases, we and others recently found that TGase 2 plays a key role in extending NF-{kappa}B activation, which contributes to the pathogenesis of disease. In the current study, we found that NF-{kappa}B activity in mouse embryogenic fibroblasts (MEFs) from TGase2{sup -/-} mice remained at the control level while the NF-{kappa}B activity of wild-type (WT) MEFs was highly increased under hypoxic stress. Using the obstructive nephropathy model, we found that NF-{kappa}B activity remained at the control level in TGase2{sup -/-} mouse kidney tissues, as measured by COX-2 expression, but was highly increased in WT tissues. We conclude that TGase 2 gene ablation reduces the duration of NF-{kappa}B activation in ischemic injury.

  13. Detection analysis of surface hydroxyl active sites and simulation calculation of the surface dissociation constants of aqueous diatomite suspensions

    NASA Astrophysics Data System (ADS)

    Ma, Shu-Cui; Wang, Zhi-Gang; Zhang, Ji-Lin; Sun, De-Hui; Liu, Gui-Xia

    2015-02-01

    The surface properties of the diatomite were investigated using nitrogen adsorption/deadsorption isotherms, TG-DSC, FTIR, and XPS, and surface protonation-deprotonation behavior was determined by continuous acid-base potentiometric titration technique. The diatomite sample with porous honeycomb structure has a BET specific surface area of 10.21 m2/g and large numbers of surface hydroxyl functional groups (i.e. tbnd Si-OH, tbnd Fe-OH, and tbnd Al-OH). These surface hydroxyls can be protonated or deprotonated depending on the pH of the suspension. The experimental potentiometric data in two different ionic strength solutions (0.1 and 0.05 mol/L NaCl) were fitted using ProtoFit GUI V2.1 program by applying diffuse double layer model (DLM) with three amphoteric sites and minimizing the sum of squares between a dataset derivative function and a model derivative function. The optimized surface parameters (i.e. surface dissociation constants (log K1, log K2) and surface site concentrations (log C)) of the sample were obtained. Based on the optimized surface parameters, the surface species distribution was calculated using Program-free PHREEQC 3.1.2. Thus, this work reveals considerable new information about surface protonation-deprotonation processes and surface adsorptive behaviors of the diatomite, which helps us to effectively use the cheap and cheerful diatomite clay adsorbent.

  14. Genome-Wide Association Study Reveals Constant and Specific Loci for Hematological Traits at Three Time Stages in a White Duroc × Erhualian F2 Resource Population

    PubMed Central

    Zhang, Zhiyan; Hong, Yuan; Gao, Jun; Xiao, Shijun; Ma, Junwu; Zhang, Wanchang; Ren, Jun; Huang, Lusheng

    2013-01-01

    Hematological traits are important indicators of immune function and have been commonly examined as biomarkers of disease and disease severity in humans. Pig is an ideal biomedical model for human diseases due to its high degree of similarity with human physiological characteristics. Here, we conducted genome-wide association studies (GWAS) for 18 hematological traits at three growth stages (days 18, 46 and 240) in a White Duroc × Erhualian F2 intercross. In total, we identified 38 genome-wide significant regions containing 185 genome-wide significant SNPs by single-marker GWAS or LONG-GWAS. The significant regions are distributed on pig chromosomes (SSC) 1, 4, 5, 7, 8, 10, 11, 12, 13, 17 and 18, and most of significant SNPs reside on SSC7 and SSC8. Of the 38 significant regions, 7 show constant effects on hematological traits across the whole life stages, and 6 regions have time-specific effects on the measured traits at early or late stages. The most prominent locus is the genomic region between 32.36 and 84.49 Mb on SSC8 that is associated with multiple erythroid traits. The KIT gene in this region appears to be a promising candidate gene. The findings improve our understanding of the genetic architecture of hematological traits in pigs. Further investigations are warranted to characterize the responsible gene(s) and causal variant(s) especially for the major loci on SSC7 and SSC8. PMID:23691082

  15. A Neurophysiological Approach for Evaluating Noise-Induced Sleep Disturbance: Calculating the Time Constant of the Dynamic Characteristics in the Brainstem

    PubMed Central

    Tagusari, Junta; Matsui, Toshihito

    2016-01-01

    Chronic sleep disturbance induced by traffic noise is considered to cause environmental sleep disorder, which increases the risk of cardiovascular disease, stroke, diabetes and other stress-related diseases. However, noise indices for the evaluation of sleep disturbance are not based on the neurophysiological process of awakening regulated by the brainstem. In this study, through the neurophysiological approach, we attempted (1) to investigate the thresholds of awakening due to external stimuli in the brainstem; (2) to evaluate the dynamic characteristics in the brainstem and (3) to verify the validity of existing noise indices. Using the mathematical Phillips–Robinson model, we obtained thresholds of awakening in the brainstem for different durations of external stimuli. The analysis revealed that the brainstem seemed insensitive to short stimuli and that the response to external stimuli in the brainstem could be approximated by a first-order lag system with a time constant of 10–100 s. These results suggest that the brainstem did not integrate sound energy as external stimuli, but neuroelectrical signals from auditory nerve. To understand the awakening risk accumulated in the brainstem, we introduced a new concept of “awakening potential” instead of sound energy. PMID:27023587

  16. Green technology effect of injection pressure, timing and compression ratio in constant pressure heat addition cycle by an eco-friendly material.

    PubMed

    Karthikayan, S; Sankaranarayanan, G; Karthikeyan, R

    2015-11-01

    Present energy strategies focus on environmental issues, especially environmental pollution prevention and control by eco-friendly green technologies. This includes, increase in the energy supplies, encouraging cleaner and more efficient energy management, addressing air pollution, greenhouse effect, global warming, and climate change. Biofuels provide the panorama of new fiscal opportunities for people in rural area for meeting their need and also the demand of the local market. Biofuels concern protection of the environment and job creation. Renewable energy sources are self-reliance resources, have the potential in energy management with less emissions of air pollutants. Biofuels are expected to reduce dependability on imported crude oil with connected economic susceptibility, reduce greenhouse gases, other pollutants and invigorate the economy by increasing demand and prices for agricultural products. The use of neat paradise tree oil and induction of eco-friendly material Hydrogen through inlet manifold in a constant pressure heat addition cycle engine (diesel engine) with optimized engine operating parameters such as injection timing, injection pressure and compression ratio. The results shows the heat utilization efficiency for neat vegetable oil is 29% and neat oil with 15% Hydrogen as 33%. The exhaust gas temperature (EGT) for 15% of H2 share as 450°C at full load and the heat release of 80J/deg. crank angle for 15% Hydrogen energy share.

  17. Green technology effect of injection pressure, timing and compression ratio in constant pressure heat addition cycle by an eco-friendly material.

    PubMed

    Karthikayan, S; Sankaranarayanan, G; Karthikeyan, R

    2015-11-01

    Present energy strategies focus on environmental issues, especially environmental pollution prevention and control by eco-friendly green technologies. This includes, increase in the energy supplies, encouraging cleaner and more efficient energy management, addressing air pollution, greenhouse effect, global warming, and climate change. Biofuels provide the panorama of new fiscal opportunities for people in rural area for meeting their need and also the demand of the local market. Biofuels concern protection of the environment and job creation. Renewable energy sources are self-reliance resources, have the potential in energy management with less emissions of air pollutants. Biofuels are expected to reduce dependability on imported crude oil with connected economic susceptibility, reduce greenhouse gases, other pollutants and invigorate the economy by increasing demand and prices for agricultural products. The use of neat paradise tree oil and induction of eco-friendly material Hydrogen through inlet manifold in a constant pressure heat addition cycle engine (diesel engine) with optimized engine operating parameters such as injection timing, injection pressure and compression ratio. The results shows the heat utilization efficiency for neat vegetable oil is 29% and neat oil with 15% Hydrogen as 33%. The exhaust gas temperature (EGT) for 15% of H2 share as 450°C at full load and the heat release of 80J/deg. crank angle for 15% Hydrogen energy share. PMID:26025643

  18. A constant-alpha force-free-field analysis of the active region AR 4711 of February, 1986

    NASA Technical Reports Server (NTRS)

    Yang, Hai-Shou; Hong, Q. F.; Ding, Y. J.

    1988-01-01

    The theory of Yang et al. (1983) is used to analyze the large active region AR 4711 of Feb. 1986. This region stored between 0.01 x 10 to the 32nd and 5.36 x 10 to the 32nd erg of extractable free magnetic energy, sufficient to supply the energies of the observed flare activities in this region. The region was an energetic quadrupolar sunspot group, occurring during solar minimum; this group was strongly twisted and produced many intense flares.

  19. Oxidation of substituted phenols in the environment: A QSAR analysis of rate constants for reaction with singlet oxygen. [Quantitative Structure-Activity Relationship

    SciTech Connect

    Tratnyek, P.G.; Holgne, J. , Duebendorf )

    1991-09-01

    Substituted phenols can be oxidized by singlet oxygen ({sup 1}O{sub 2}), which is formed in sunlit surface waters, and it has been suggested that this reaction may contribute to the environmental fate of phenolic substances. In aqueous solution, the observed rate of phenol disappearance is due to reaction of both the phenolate anion and the undissociated phenol. In order to quantify the effect of substituents on the rates of these reactions, second-order rate constants have been measured for both species for 22 substituted phenols by use of a model system containing the sensitizer rose bengal. Correlation analysis based on half-wave oxidation potentials, E{sub 1/2}, and on {sigma} constants reveals significant quantitative structure-activity relationships (QSARs) for both the undissociated phenols and the phenolate anions. Ortho- and multisubstituted phenols have been included in the correlations. These QSARs are consistent with the rate-limiting formation of a precursor complex with a small amount of charge-transfer character and can be used to predict additional rate constants for a wide range of environmentally significant substituted phenols.

  20. New Quasar Studies Keep Fundamental Physical Constant Constant

    NASA Astrophysics Data System (ADS)

    2004-03-01

    atoms together and the way light interacts with atoms. But are these fundamental physical constants really constant? Are those numbers always the same, everywhere in the Universe and at all times? This is not as naive a question as it may seem. Contemporary theories of fundamental interactions, such as the Grand Unification Theory or super-string theories that treat gravity and quantum mechanics in a consistent way, not only predict a dependence of fundamental physical constants with energy - particle physics experiments have shown the fine structure constant to grow to a value of about 1/128 at high collision energies - but allow for their cosmological time and space variations. A time dependence of the fundamental constants could also easily arise if, besides the three space dimensions, there exist more hidden dimensions. Already in 1955, the Russian physicist Lev Landau considered the possibility of a time dependence of alpha. In the late 1960s, George Gamow in the United States suggested that the charge of the electron, and therefore also alpha, may vary. It is clear however that such changes, if any, cannot be large or they would already have been detected in comparatively simple experiments. Tracking these possible changes thus requires the most sophisticated and precise techniques. Looking back in time In fact, quite strong constraints are already known to exist for the possible variation of the fine structure constant alpha. One such constraint is of geological nature. It is based on measures taken in the ancient natural fission reactor located near Oklo (Gabon, West Africa) and which was active roughly 2,000 million years ago. By studying the distribution of a given set of elements - isotopes of the rare earths, for example of samarium - which were produced by the fission of uranium, one can estimate whether the physical process happened at a faster or slower pace than we would expect it nowadays. Thus we can measure a possible change of the value of the

  1. Homonuclear BIRD-decoupled spectra for measuring one-bond couplings with highest resolution: CLIP/CLAP-RESET and constant-time-CLIP/CLAP-RESET

    NASA Astrophysics Data System (ADS)

    Reinsperger, Tony; Luy, Burkhard

    2014-02-01

    Heteronuclear one-bond couplings are of interest for various aspects of structural analysis of small organic molecules, including for example the distinction of axial and equatorial protons or the use of RDCs as angular constraints. Such couplings are most easily measured from pure doublets in HSQC-type spectra. Recently, the fully decoupled RESET HSQC experiment was reported and several other so-called pure-shift methods followed that allow for the removal of splittings due to homonuclear scalar interactions in one and two-dimensional NMR. In this work we present broadband homonuclear decoupled CLIP/CLAP-RESET experiments based on an isotope-selective BIRD filter element using a recently reported improved version of Zangger-Sterk data chunking. The concatenated FIDs result in multiplets in which most homonuclear splittings are removed while the heteronuclear one-bond couplings are retained. Couplings can be extracted in an IPAP fashion without scaling of subspectra by the use of optimized coherence transfer elements like the COB-INEPT. The method leads to complete homonuclear decoupling for CH groups and CH3 groups in isotropic samples, but leaves residual splittings with antiphase contributions for e.g. CH2 groups due to 2JHH coupling evolution that is not affected by the BIRD element. For this case we present a constant-time version of the proposed BIRD decoupling scheme with full homonuclear decoupling. In addition, the effects of strong coupling are discussed. Strong coupling artifacts cannot be circumvented, but the proposed experiments allow their distinct recognition.

  2. Estimating the plasma effect-site equilibrium rate constant (Ke₀) of propofol by fitting time of loss and recovery of consciousness.

    PubMed

    Wu, Qi; Sun, Baozhu; Wang, Shuqin; Zhao, Lianying; Qi, Feng

    2013-01-01

    The present paper proposes a new approach for fitting the plasma effect-site equilibrium rate constant (Ke0) of propofol to satisfy the condition that the effect-site concentration (Ce) is equal at the time of loss of consciousness (LOC) and recovery of consciousness (ROC). Forty patients receiving intravenous anesthesia were divided into 4 groups and injected propofol 1.4, 1.6, 1.8, or 2 mg/kg at 1,200 mL/h. Durations from the start of injection to LOC and to ROC were recorded. LOC and ROC were defined as an observer's assessment of alertness and sedation scale change from 3 to 2 and from 2 to 3, respectively. Software utilizing bisection method iteration algorithms was built. Then, Ke0 satisfying the CeLOC=CeROC condition was estimated. The accuracy of the Ke0 estimated by our method was compared with the Diprifusor TCI Pump built-in Ke0 (0.26 min(-1)), and the Orchestra Workstation built-in Ke0 (1.21 min(-1)) in another group of 21 patients who were injected propofol 1.4 to 2 mg/kg. Our results show that the population Ke0 of propofol was 0.53 ± 0.18 min(-1). The regression equation for adjustment by dose (mg/kg) and age was Ke0=1.42-0.30 × dose-0.0074 × age. Only Ke0 adjusted by dose and age achieved the level of accuracy required for clinical applications. We conclude that the Ke0 estimated based on clinical signs and the two-point fitting method significantly improved the ability of CeLOC to predict CeROC. However, only the Ke0 adjusted by dose and age and not a fixed Ke0 value can meet clinical requirements of accuracy.

  3. Young Urban African American Adolescents' Experience of Discretionary Time Activities

    ERIC Educational Resources Information Center

    Bohnert, Amy M.; Richards, Maryse H.; Kolmodin, Karen E.; Lakin, Brittany L.

    2008-01-01

    This cross-sectional study examined the daily discretionary time experiences of 246 (107 boys, 139 girls) fifth through eighth grade urban African American adolescents using the Experience Sampling Method. Relations between the types of activities (i.e., active structured, active unstructured, passive unstructured) engaged in during discretionary…

  4. (.)VO(2) and EMG activity kinetics during moderate and severe constant work rate exercise in trained cyclists.

    PubMed

    Cleuziou, Christophe; Perrey, Stephane; Borrani, Fabio; Lecoq, Anne Marie; Courteix, Daniel; Germain, Philippe; Obert, Philippe

    2004-12-01

    The purpose of this study was to compare O(2) uptake ((.)VO(2)) and muscle electromyography activity kinetics during moderate and severe exercise to test the hypothesis of progressive recruitment of fast-twitch fibers in the explanation of the VO(2) slow component. After an incremental test to exhaustion, 7 trained cyclists (mean +/- SD, 61.4 +/- 4.2 ml x min(-1) x kg(- 1)) performed several square-wave transitions for 6 min at moderate and severe intensities on a bicycle ergometer. The (.)VO(2) response and the electrical activity (i.e., median power frequency, MDF) of the quadriceps vastus lateralis and vastus medialis of both lower limbs were measured continuously during exercise. After 2 to 3 min of exercise onset, MDF values increased similarly during moderate and severe exercise for almost all muscles whereas a (.)VO(2) slow component occurred during severe exercise. There was no relationship between the increase of MDF values and the magnitude of the (.)VO(2) slow component during the severe exercise. These results suggest that the origin of the slow component may not be due to the progressive recruitment of fast-twitch fibers.

  5. Multiscale time activity data exploration via temporal clustering visualization spreadsheet.

    PubMed

    Woodring, Jonathan; Shen, Han-Wei

    2009-01-01

    Time-varying data is usually explored by animation or arrays of static images. Neither is particularly effective for classifying data by different temporal activities. Important temporal trends can be missed due to the lack of ability to find them with current visualization methods. In this paper, we propose a method to explore data at different temporal resolutions to discover and highlight data based upon time-varying trends. Using the wavelet transform along the time axis, we transform data points into multi-scale time series curve sets. The time curves are clustered so that data of similar activity are grouped together, at different temporal resolutions. The data are displayed to the user in a global time view spreadsheet where she is able to select temporal clusters of data points, and filter and brush data across temporal scales. With our method, a user can interact with data based on time activities and create expressive visualizations. PMID:19008560

  6. COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses. VII. Time delays and the Hubble constant from WFI J2033-4723

    NASA Astrophysics Data System (ADS)

    Vuissoz, C.; Courbin, F.; Sluse, D.; Meylan, G.; Chantry, V.; Eulaers, E.; Morgan, C.; Eyler, M. E.; Kochanek, C. S.; Coles, J.; Saha, P.; Magain, P.; Falco, E. E.

    2008-09-01

    Gravitationally lensed quasars can be used to map the mass distribution in lensing galaxies and to estimate the Hubble constant H0 by measuring the time delays between the quasar images. Here we report the measurement of two independent time delays in the quadruply imaged quasar WFI J2033-4723 (z = 1.66). Our data consist of R-band images obtained with the Swiss 1.2 m EULER telescope located at La Silla and with the 1.3 m SMARTS telescope located at Cerro Tololo. The light curves have 218 independent epochs spanning 3 full years of monitoring between March 2004 and May 2007, with a mean temporal sampling of one observation every 4th day. We measure the time delays using three different techniques, and we obtain Δ tB-A = 35.5 ± 1.4 days (3.8%) and Δ tB-C = 62.6+ 4.1- 2.3~days ~ (+ 6.5%- 3.7%), where A is a composite of the close, merging image pair. After correcting for the time delays, we find R-band flux ratios of FA/FB = 2.88 ± 0.04, FA/FC = 3.38 ± 0.06, and FA1/FA2 = 1.37 ± 0.05 with no evidence for microlensing variability over a time scale of three years. However, these flux ratios do not agree with those measured in the quasar emission lines, suggesting that longer term microlensing is present. Our estimate of H0 agrees with the concordance value: non-parametric modeling of the lensing galaxy predicts H0 = 67+13-10 km s-1 Mpc-1, while the Single Isothermal Sphere model yields H0 = 63+7-3 km s-1 Mpc-1 (68% confidence level). More complex lens models using a composite de Vaucouleurs plus NFW galaxy mass profile show twisting of the mass isocontours in the lensing galaxy, as do the non-parametric models. As all models also require a significant external shear, this suggests that the lens is a member of the group of galaxies seen in field of view of WFI J2033-4723. Based on observations obtained with the 1.2 m EULER Swiss Telescope, the 1.3 m Small and Moderate Aperture Research Telescope System (SMARTS) which is operated by the SMARTS Consortium, and the

  7. Time Perspective and Physical Activity among Central Appalachian Adolescents

    ERIC Educational Resources Information Center

    Gulley, Tauna

    2013-01-01

    Time perspective is a cultural behavioral concept that reflects individuals' orientations or attitudes toward the past, present, or future. Individuals' time perspectives influence their choices regarding daily activities. Time perspective is an important consideration when teaching adolescents about the importance of being physically…

  8. American Time Use Survey: Sleep Time and Its Relationship to Waking Activities

    PubMed Central

    Basner, Mathias; Fomberstein, Kenneth M.; Razavi, Farid M.; Banks, Siobhan; William, Jeffrey H.; Rosa, Roger R.; Dinges, David F.

    2007-01-01

    Study Objectives: To gain some insight into how various behavioral (lifestyle) factors influence sleep duration, by investigation of the relationship of sleep time to waking activities using the American Time Use Survey (ATUS). Design: Cross-sectional data from ATUS, an annual telephone survey of a population sample of US citizens who are interviewed regarding how they spent their time during a 24-hour period between 04:00 on the previous day and 04:00 on the interview day. Participants: Data were pooled from the 2003, 2004, and 2005 ATUS databases involving N=47,731 respondents older than 14 years of age. Interventions: N/A Results: Adjusted multiple linear regression models showed that the largest reciprocal relationship to sleep was found for work time, followed by travel time, which included commute time. Only shorter than average sleepers (<7.5 h) spent more time socializing, relaxing, and engaging in leisure activities, while both short (<5.5 h) and long sleepers (≥8.5 h) watched more TV than the average sleeper. The extent to which sleep time was exchanged for waking activities was also shown to depend on age and gender. Sleep time was minimal while work time was maximal in the age group 45–54 yr, and sleep time increased both with lower and higher age. Conclusions: Work time, travel time, and time for socializing, relaxing, and leisure are the primary activities reciprocally related to sleep time among Americans. These activities may be confounding the frequently observed association between short and long sleep on one hand and morbidity and mortality on the other hand and should be controlled for in future studies. Citation: Basner M; Fomberstein KM; Razavi FM; Banks S; William JH; Rosa RR; Dinges DF. American time use survey: sleep time and its relationship to waking activities. SLEEP 2007;30(9):1085-1095. PMID:17910380

  9. Real-time spectroscopic monitoring of photocatalytic activity promoted by graphene in a microfluidic reactor

    NASA Astrophysics Data System (ADS)

    Li, Yifan; Lin, Beichen; Ge, Likai; Guo, Hongchen; Chen, Xinyi; Lu, Miao

    2016-06-01

    Photocatalytic microreactors have been utilized as rapid, versatile platforms for the characterization of photocatalysts. In this work, a photocatalytic microreactor integrated with absorption spectroscopy was proposed for the real-time monitoring of photocatalytic activity using different catalysts. The validity of this method was investigated by the rapid screening on the photocatalytic performance of a titanium oxide (TiO2)-decorated graphene oxide (GO) sheet for the degradation of methylene blue under monochromatic visible irradiation. The sampling interval time could be minimized to 10 s for achieving real-time detection. The best photocatalytic activity was observed for an optimized TiO2/GO weight mixing ratio of 7:11, with a reaction rate constant up to 0.067 min‑1. The addition of GO into TiO2 enhances photocatalytic activity and adsorption of MB molecules. The synthetic reaction rate constant was up to approximately 0.11 min‑1, which was also the highest among the catalysts. The microreactor exhibited good sensitivity and reproducibility without weakening the performance of the photocatalysts. Consequently, the photocatalytic microreactor is promising as a simple, portable, and rapid screening tool for new photocatalysts.

  10. Real-time spectroscopic monitoring of photocatalytic activity promoted by graphene in a microfluidic reactor

    PubMed Central

    Li, Yifan; Lin, Beichen; Ge, Likai; Guo, Hongchen; Chen, Xinyi; Lu, Miao

    2016-01-01

    Photocatalytic microreactors have been utilized as rapid, versatile platforms for the characterization of photocatalysts. In this work, a photocatalytic microreactor integrated with absorption spectroscopy was proposed for the real-time monitoring of photocatalytic activity using different catalysts. The validity of this method was investigated by the rapid screening on the photocatalytic performance of a titanium oxide (TiO2)-decorated graphene oxide (GO) sheet for the degradation of methylene blue under monochromatic visible irradiation. The sampling interval time could be minimized to 10 s for achieving real-time detection. The best photocatalytic activity was observed for an optimized TiO2/GO weight mixing ratio of 7:11, with a reaction rate constant up to 0.067 min−1. The addition of GO into TiO2 enhances photocatalytic activity and adsorption of MB molecules. The synthetic reaction rate constant was up to approximately 0.11 min−1, which was also the highest among the catalysts. The microreactor exhibited good sensitivity and reproducibility without weakening the performance of the photocatalysts. Consequently, the photocatalytic microreactor is promising as a simple, portable, and rapid screening tool for new photocatalysts. PMID:27346555

  11. Constant-time 2D and 3D through-bond correlation NMR spectroscopy of solids under 60 kHz MAS

    NASA Astrophysics Data System (ADS)

    Zhang, Rongchun; Ramamoorthy, Ayyalusamy

    2016-01-01

    Establishing connectivity and proximity of nuclei is an important step in elucidating the structure and dynamics of molecules in solids using magic angle spinning (MAS) NMR spectroscopy. Although recent studies have successfully demonstrated the feasibility of proton-detected multidimensional solid-state NMR experiments under ultrafast-MAS frequencies and obtaining high-resolution spectral lines of protons, assignment of proton resonances is a major challenge. In this study, we first re-visit and demonstrate the feasibility of 2D constant-time uniform-sign cross-peak correlation (CTUC-COSY) NMR experiment on rigid solids under ultrafast-MAS conditions, where the sensitivity of the experiment is enhanced by the reduced spin-spin relaxation rate and the use of low radio-frequency power for heteronuclear decoupling during the evolution intervals of the pulse sequence. In addition, we experimentally demonstrate the performance of a proton-detected pulse sequence to obtain a 3D 1H/13C/1H chemical shift correlation spectrum by incorporating an additional cross-polarization period in the CTUC-COSY pulse sequence to enable proton chemical shift evolution and proton detection in the incrementable t1 and t3 periods, respectively. In addition to through-space and through-bond 13C/1H and 13C/13C chemical shift correlations, the 3D 1H/13C/1H experiment also provides a COSY-type 1H/1H chemical shift correlation spectrum, where only the chemical shifts of those protons, which are bonded to two neighboring carbons, are correlated. By extracting 2D F1/F3 slices (1H/1H chemical shift correlation spectrum) at different 13C chemical shift frequencies from the 3D 1H/13C/1H spectrum, resonances of proton atoms located close to a specific carbon atom can be identified. Overall, the through-bond and through-space homonuclear/heteronuclear proximities determined from the 3D 1H/13C/1H experiment would be useful to study the structure and dynamics of a variety of chemical and biological

  12. Constant-time 2D and 3D through-bond correlation NMR spectroscopy of solids under 60 kHz MAS.

    PubMed

    Zhang, Rongchun; Ramamoorthy, Ayyalusamy

    2016-01-21

    Establishing connectivity and proximity of nuclei is an important step in elucidating the structure and dynamics of molecules in solids using magic angle spinning (MAS) NMR spectroscopy. Although recent studies have successfully demonstrated the feasibility of proton-detected multidimensional solid-state NMR experiments under ultrafast-MAS frequencies and obtaining high-resolution spectral lines of protons, assignment of proton resonances is a major challenge. In this study, we first re-visit and demonstrate the feasibility of 2D constant-time uniform-sign cross-peak correlation (CTUC-COSY) NMR experiment on rigid solids under ultrafast-MAS conditions, where the sensitivity of the experiment is enhanced by the reduced spin-spin relaxation rate and the use of low radio-frequency power for heteronuclear decoupling during the evolution intervals of the pulse sequence. In addition, we experimentally demonstrate the performance of a proton-detected pulse sequence to obtain a 3D (1)H/(13)C/(1)H chemical shift correlation spectrum by incorporating an additional cross-polarization period in the CTUC-COSY pulse sequence to enable proton chemical shift evolution and proton detection in the incrementable t1 and t3 periods, respectively. In addition to through-space and through-bond (13)C/(1)H and (13)C/(13)C chemical shift correlations, the 3D (1)H/(13)C/(1)H experiment also provides a COSY-type (1)H/(1)H chemical shift correlation spectrum, where only the chemical shifts of those protons, which are bonded to two neighboring carbons, are correlated. By extracting 2D F1/F3 slices ((1)H/(1)H chemical shift correlation spectrum) at different (13)C chemical shift frequencies from the 3D (1)H/(13)C/(1)H spectrum, resonances of proton atoms located close to a specific carbon atom can be identified. Overall, the through-bond and through-space homonuclear/heteronuclear proximities determined from the 3D (1)H/(13)C/(1)H experiment would be useful to study the structure and dynamics of

  13. Constants and Variables of Nature

    SciTech Connect

    Sean Carroll

    2009-04-03

    It is conventional to imagine that the various parameters which characterize our physical theories, such as the fine structure constant or Newton’s gravitational constant, are truly “constant”, in the sense that they do not change from place to place or time to time. Recent developments in both theory and observation have led us to re-examine this assumption, and to take seriously the possibility that our supposed constants are actually gradually changing. I will discuss why we might expect these parameters to vary, and what observation and experiment have to say about the issue.

  14. 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.

  15. The Elasticity of Time: Associations between Physical Activity and Use of Time in Adolescents

    ERIC Educational Resources Information Center

    Olds, Tim; Ferrar, Katia E.; Gomersall, Sjaan R.; Maher, Carol; Walters, J. L.

    2012-01-01

    The way an individual uses one's time can greatly affect his or her health. The purpose of this article was to examine the cross-sectional cross-elasticity relationships for use of time domains in a sample of Australian adolescents. This study analyzed 24-hour recall time use data collected using the Multimedia Activity Recall for Children and…

  16. Circadian Activity Rhythms, Time Urgency, and Achievement Concerns.

    ERIC Educational Resources Information Center

    Watts, Barbara L.

    Many physiological and psychological processes fluctuate throughout the day in fairly stable, rhythmic patterns. The relationship between individual differences in circadian activity rhythms and a sense of time urgency were explored as well as a number of achievement-related variables. Undergraduates (N=308), whose circadian activity rhythms were…

  17. Trajectory data analyses for pedestrian space-time activity study.

    PubMed

    Qi, Feng; Du, Fei

    2013-02-25

    It is well recognized that human movement in the spatial and temporal dimensions has direct influence on disease transmission(1-3). An infectious disease typically spreads via contact between infected and susceptible individuals in their overlapped activity spaces. Therefore, daily mobility-activity information can be used as an indicator to measure exposures to risk factors of infection. However, a major difficulty and thus the reason for paucity of studies of infectious disease transmission at the micro scale arise from the lack of detailed individual mobility data. Previously in transportation and tourism research detailed space-time activity data often relied on the time-space diary technique, which requires subjects to actively record their activities in time and space. This is highly demanding for the participants and collaboration from the participants greatly affects the quality of data(4). Modern technologies such as GPS and mobile communications have made possible the automatic collection of trajectory data. The data collected, however, is not ideal for modeling human space-time activities, limited by the accuracies of existing devices. There is also no readily available tool for efficient processing of the data for human behavior study. We present here a suite of methods and an integrated ArcGIS desktop-based visual interface for the pre-processing and spatiotemporal analyses of trajectory data. We provide examples of how such processing may be used to model human space-time activities, especially with error-rich pedestrian trajectory data, that could be useful in public health studies such as infectious disease transmission modeling. The procedure presented includes pre-processing, trajectory segmentation, activity space characterization, density estimation and visualization, and a few other exploratory analysis methods. Pre-processing is the cleaning of noisy raw trajectory data. We introduce an interactive visual pre-processing interface as well as an

  18. Trajectory data analyses for pedestrian space-time activity study.

    PubMed

    Qi, Feng; Du, Fei

    2013-01-01

    It is well recognized that human movement in the spatial and temporal dimensions has direct influence on disease transmission(1-3). An infectious disease typically spreads via contact between infected and susceptible individuals in their overlapped activity spaces. Therefore, daily mobility-activity information can be used as an indicator to measure exposures to risk factors of infection. However, a major difficulty and thus the reason for paucity of studies of infectious disease transmission at the micro scale arise from the lack of detailed individual mobility data. Previously in transportation and tourism research detailed space-time activity data often relied on the time-space diary technique, which requires subjects to actively record their activities in time and space. This is highly demanding for the participants and collaboration from the participants greatly affects the quality of data(4). Modern technologies such as GPS and mobile communications have made possible the automatic collection of trajectory data. The data collected, however, is not ideal for modeling human space-time activities, limited by the accuracies of existing devices. There is also no readily available tool for efficient processing of the data for human behavior study. We present here a suite of methods and an integrated ArcGIS desktop-based visual interface for the pre-processing and spatiotemporal analyses of trajectory data. We provide examples of how such processing may be used to model human space-time activities, especially with error-rich pedestrian trajectory data, that could be useful in public health studies such as infectious disease transmission modeling. The procedure presented includes pre-processing, trajectory segmentation, activity space characterization, density estimation and visualization, and a few other exploratory analysis methods. Pre-processing is the cleaning of noisy raw trajectory data. We introduce an interactive visual pre-processing interface as well as an

  19. Physical Activity, Study Sitting Time, Leisure Sitting Time, and Sleep Time Are Differently Associated With Obesity in Korean Adolescents

    PubMed Central

    Kong, Il Gyu; Lee, Hyo-Jeong; Kim, So Young; Sim, Songyong; Choi, Hyo Geun

    2015-01-01

    Abstract Low physical activity, long leisure sitting time, and short sleep time are risk factors for obesity, but the association with study sitting time is unknown. The objective of this study was to evaluate the association between these factors and obesity. We analyzed the association between physical activity, study sitting time, leisure sitting time, and sleep time and subject weight (underweight, healthy weight, overweight, and obese), using data from a large population-based survey, the 2013 Korea Youth Risk Behavior Web-based Survey. Data from 53,769 participants were analyzed using multinomial logistic regression analyses with complex sampling. Age, sex, region of residence, economic level, smoking, stress level, physical activity, sitting time for study, sitting time for leisure, and sleep time were adjusted as the confounders. Low physical activity (adjusted odds ratios [AORs] = 1.03, 1.12) and long leisure sitting time (AORs = 1.15, 1.32) were positively associated with overweight and obese. Low physical activity (AOR = 1.33) and long leisure sitting time (AOR = 1.12) were also associated with underweight. Study sitting time was negatively associated with underweight (AOR = 0.86) but was unrelated to overweight (AOR = 0.97, 95% confidence interval [CI] = 0.91–1.03) and obese (AOR = 0.94, 95% CI = 0.84–1.04). Sleep time (<6 hours; ≥6 hours, <7 hours; ≥7 hours, <8 hours) was adversely associated with underweight (AORs = 0.67, 0.79, and 0.88) but positively associated with overweight (AORs = 1.19, 1.17, and 1.08) and obese (AORs = 1.33, 1.36, and 1.30) in a dose–response relationship. In adolescents, increasing physical activity, decreasing leisure sitting time, and obtaining sufficient sleep would be beneficial in maintaining a healthy weight. However, study sitting time was not associated with overweight or obese. PMID:26554807

  20. Temporal variation of coupling constants and nucleosynthesis

    NASA Astrophysics Data System (ADS)

    Oberhummer, H.; Csótó, A.; Fairbairn, M.; Schlattl, H.; Sharma, M. M.

    2003-05-01

    We investigate the triple-alpha process and the Oklo phenomenon to obtain constraints on possible cosmological time variations of fundamental constants. Specifically we study cosmological temporal constraints for the fine structure constant and nucleon and meson masses.

  1. Time required for motor activity in lucid dreams.

    PubMed

    Erlacher, Daniel; Schredl, Michael

    2004-12-01

    The present study investigated the relationship between the time required for specific tasks (counting and performing squats) in lucid dreams and in the waking state. Five proficient lucid dreamers (26-34 yr. old, M=29.8, SD=3.0; one woman and four men) participated. Analysis showed that the time needed for counting in a lucid dream is comparable to the time needed for counting in wakefulness, but motor activities required more time in lucid dreams than in the waking state. PMID:15739850

  2. Time required for motor activity in lucid dreams.

    PubMed

    Erlacher, Daniel; Schredl, Michael

    2004-12-01

    The present study investigated the relationship between the time required for specific tasks (counting and performing squats) in lucid dreams and in the waking state. Five proficient lucid dreamers (26-34 yr. old, M=29.8, SD=3.0; one woman and four men) participated. Analysis showed that the time needed for counting in a lucid dream is comparable to the time needed for counting in wakefulness, but motor activities required more time in lucid dreams than in the waking state.

  3. Viscous time lags between starburst and AGN activity

    NASA Astrophysics Data System (ADS)

    Blank, Marvin; Duschl, Wolfgang J.

    2016-10-01

    There is strong observational evidence indicating a time lag of order of some 100 Myr between the onset of starburst and AGN activity in galaxies. Dynamical time lags have been invoked to explain this. We extend this approach by introducing a viscous time lag the gas additionally needs to flow through the AGN's accretion disc before it reaches the central black hole. Our calculations reproduce the observed time lags and are in accordance with the observed correlation between black hole mass and stellar velocity dispersion.

  4. Ionospheric Electron Density during Magnetically Active Times over Istanbul

    NASA Astrophysics Data System (ADS)

    Naz Erbaş, Bute; Kaymaz, Zerefsan; Ceren Moral, Aysegul; Emine Ceren Kalafatoglu Eyiguler, R. A..

    2016-07-01

    In this study, we analyze electron density variations over Istanbul using Dynasonde observations during the magnetically active times. In order to perform statistical analyses, we first determined magnetic storms and magnetospheric substorm intervals from October 2012 to October 2015 using Kyoto's magnetic index data. Corresponding ionospheric parameters, such as critical frequency of F2 region (foF2), maximum electron density height (hmF2), total electron density (TEC) etc. were retrieved from Dynasonde data base at Istanbul Technical University's Space Weather Laboratory. To understand the behavior of electron density during the magnetically active times, we remove the background quiet time variations first and then quantify the anomalies. In this presentation, we will report results from our preliminary analyses from the selected cases corresponding to the strong magnetic storms. Initial results show lower electron densities at noon times and higher electron densities in the late afternoon toward sunset times when compared to the electron densities of magnetically quiet times. We also compare the results with IRI and TIEGCM ionospheric models in order to understand the physical and dynamical causes of these variations. During the presentation we will also discuss the role of these changes during the magnetically active times on the GPS communications through ionosphere.

  5. Effect of altering starting length and activation timing of muscle on fiber strain and muscle damage.

    PubMed

    Butterfield, Timothy A; Herzog, Walter

    2006-05-01

    Muscle strain injuries are some of the most frequent injuries in sports and command a great deal of attention in an effort to understand their etiology. These injuries may be the culmination of a series of subcellular events accumulated through repetitive lengthening (eccentric) contractions during exercise, and they may be influenced by a variety of variables including fiber strain magnitude, peak joint torque, and starting muscle length. To assess the influence of these variables on muscle injury magnitude in vivo, we measured fiber dynamics and joint torque production during repeated stretch-shortening cycles in the rabbit tibialis anterior muscle, at short and long muscle lengths, while varying the timing of activation before muscle stretch. We found that a muscle subjected to repeated stretch-shortening cycles of constant muscle-tendon unit excursion exhibits significantly different joint torque and fiber strains when the timing of activation or starting muscle length is changed. In particular, measures of fiber strain and muscle injury were significantly increased by altering activation timing and increasing the starting length of the muscle. However, we observed differential effects on peak joint torque during the cyclic stretch-shortening exercise, as increasing the starting length of the muscle did not increase torque production. We conclude that altering activation timing and muscle length before stretch may influence muscle injury by significantly increasing fiber strain magnitude and that fiber dynamics is a more important variable than muscle-tendon unit dynamics and torque production in influencing the magnitude of muscle injury.

  6. Solar Irradiance Variations on Active Region Time Scales

    NASA Technical Reports Server (NTRS)

    Labonte, B. J. (Editor); Chapman, G. A. (Editor); Hudson, H. S. (Editor); Willson, R. C. (Editor)

    1984-01-01

    The variations of the total solar irradiance is an important tool for studying the Sun, thanks to the development of very precise sensors such as the ACRIM instrument on board the Solar Maximum Mission. The largest variations of the total irradiance occur on time scales of a few days are caused by solar active regions, especially sunspots. Efforts were made to describe the active region effects on total and spectral irradiance.

  7. Planning in time - Windows and durations for activities and goals

    NASA Technical Reports Server (NTRS)

    Vere, S. A.

    1983-01-01

    The present general purpose automated planner/scheduler generates parallel plans aimed at the achievement of goals having imposed time constraints, with both durations and start time windows being specifiable for sets of goal conditions. Deterministic durations of such parallel plan activities as actions, events triggered by circumstances, inferences, and scheduled events entirely outside the actor's control, are explicitly modeled and may be any computable function of the activity variables. The final plan network resembles a PERT chart. Examples are given from the traditional 'blocksworld', and from a realistic 'Spaceworld' in which an autonomous spacecraft photographs objects in deep space and transmits the information to earth.

  8. When constants are important

    SciTech Connect

    Beiu, V.

    1997-04-01

    In this paper the authors discuss several complexity aspects pertaining to neural networks, commonly known as the curse of dimensionality. The focus will be on: (1) size complexity and depth-size tradeoffs; (2) complexity of learning; and (3) precision and limited interconnectivity. Results have been obtained for each of these problems when dealt with separately, but few things are known as to the links among them. They start by presenting known results and try to establish connections between them. These show that they are facing very difficult problems--exponential growth in either space (i.e. precision and size) and/or time (i.e., learning and depth)--when resorting to neural networks for solving general problems. The paper will present a solution for lowering some constants, by playing on the depth-size tradeoff.

  9. Patterns of Activity Revealed by a Time Lag Analysis of a Model Active Region

    NASA Astrophysics Data System (ADS)

    Bradshaw, Stephen; Viall, Nicholeen

    2016-05-01

    We investigate the global activity patterns predicted from a model active region heated by distributions of nanoflares that have a range of average frequencies. The activity patterns are manifested in time lag maps of narrow-band instrument channel pairs. We combine an extrapolated magnetic skeleton with hydrodynamic and forward modeling codes to create a model active region, and apply the time lag method to synthetic observations. Our aim is to recover some typical properties and patterns of activity observed in active regions. Our key findings are: 1. Cooling dominates the time lag signature and the time lags between the channel pairs are generally consistent with observed values. 2. Shorter coronal loops in the core cool more quickly than longer loops at the periphery. 3. All channel pairs show zero time lag when the line-of-sight passes through coronal loop foot-points. 4. There is strong evidence that plasma must be re-energized on a time scale comparable to the cooling timescale to reproduce the observed coronal activity, but it is likely that a relatively broad spectrum of heating frequencies operates across active regions. 5. Due to their highly dynamic nature, we find nanoflare trains produce zero time lags along entire flux tubes in our model active region that are seen between the same channel pairs in observed active regions.

  10. A constant threat for HIV: Fc-engineering to enhance broadly neutralizing antibody activity for immunotherapy of the acquired immunodeficiency syndrome.

    PubMed

    Nimmerjahn, Falk

    2015-08-01

    Passive immunotherapy with polyclonal or hyperimmune serum immunoglobulin G (IgG) preparations provides an efficient means of protecting immunocompromised patients from microbial infections. More recently, the use of passive immunotherapy to prevent or to treat established infections with the human immunodeficiency virus (HIV) has gained much attention, due to promising preclinical data obtained in monkey and humanized mouse in vivo model systems, demonstrating that the transfer of HIV-specific antibodies can not only prevent HIV infection, but also diminish virus load during chronic infection. Furthermore, an array of broadly neutralizing HIV-specific antibodies has become available and the importance of the IgG constant region as a critical modulator of broadly neutralizing activity has been demonstrated. The aim of this review is to summarize the most recent findings with regard to the molecular and cellular mechanisms responsible for antibody-mediated clearance of HIV infection, and to discuss how this may help to improve HIV therapy via optimizing Fcγ-receptor-dependent activities of HIV-specific antibodies.

  11. Effective cosmological constant induced by stochastic fluctuations of Newton's constant

    NASA Astrophysics Data System (ADS)

    de Cesare, Marco; Lizzi, Fedele; Sakellariadou, Mairi

    2016-09-01

    We consider implications of the microscopic dynamics of spacetime for the evolution of cosmological models. We argue that quantum geometry effects may lead to stochastic fluctuations of the gravitational constant, which is thus considered as a macroscopic effective dynamical quantity. Consistency with Riemannian geometry entails the presence of a time-dependent dark energy term in the modified field equations, which can be expressed in terms of the dynamical gravitational constant. We suggest that the late-time accelerated expansion of the Universe may be ascribed to quantum fluctuations in the geometry of spacetime rather than the vacuum energy from the matter sector.

  12. Understanding human activity patterns based on space-time-semantics

    NASA Astrophysics Data System (ADS)

    Huang, Wei; Li, Songnian

    2016-11-01

    Understanding human activity patterns plays a key role in various applications in an urban environment, such as transportation planning and traffic forecasting, urban planning, public health and safety, and emergency response. Most existing studies in modeling human activity patterns mainly focus on spatiotemporal dimensions, which lacks consideration of underlying semantic context. In fact, what people do and discuss at some places, inferring what is happening at the places, cannot be simple neglected because it is the root of human mobility patterns. We believe that the geo-tagged semantic context, representing what individuals do and discuss at a place and a specific time, drives a formation of specific human activity pattern. In this paper, we aim to model human activity patterns not only based on space and time but also with consideration of associated semantics, and attempt to prove a hypothesis that similar mobility patterns may have different motivations. We develop a spatiotemporal-semantic model to quantitatively express human activity patterns based on topic models, leading to an analysis of space, time and semantics. A case study is conducted using Twitter data in Toronto based on our model. Through computing the similarities between users in terms of spatiotemporal pattern, semantic pattern and spatiotemporal-semantic pattern, we find that only a small number of users (2.72%) have very similar activity patterns, while the majority (87.14%) show different activity patterns (i.e., similar spatiotemporal patterns and different semantic patterns, similar semantic patterns and different spatiotemporal patterns, or different in both). The population of users that has very similar activity patterns is decreased by 56.41% after incorporating semantic information in the corresponding spatiotemporal patterns, which can quantitatively prove the hypothesis.

  13. Varying Constants, Gravitation and Cosmology

    NASA Astrophysics Data System (ADS)

    Uzan, Jean-Philippe

    2011-12-01

    Fundamental constants are a cornerstone of our physical laws. Any constant varying in space and/or time would reflect the existence of an almost massless field that couples to matter. This will induce a violation of the universality of free fall. Thus, it is of utmost importance for our understanding of gravity and of the domain of validity of general relativity to test for their constancy. We detail the relations between the constants, the tests of the local position invariance and of the universality of free fall. We then review the main experimental and observational constraints that have been obtained from atomic clocks, the Oklo phenomenon, solar system observations, meteorite dating, quasar absorption spectra, stellar physics, pulsar timing, the cosmic microwave background and big bang nucleosynthesis. At each step we describe the basics of each system, its dependence with respect to the constants, the known systematic effects and the most recent constraints that have been obtained. We then describe the main theoretical frameworks in which the low-energy constants may actually be varying and we focus on the unification mechanisms and the relations between the variation of different constants. To finish, we discuss the more speculative possibility of understanding their numerical values and the apparent fine-tuning that they confront us with.

  14. Decentralized testing for prothrombin time and activated partial thromboplastin time using a dry chemistry portable analyzer.

    PubMed

    Rose, V L; Dermott, S C; Murray, B F; McIver, M M; High, K A; Oberhardt, B J

    1993-06-01

    Previous work has established the precision and accuracy of a portable blood coagulation analysis system using paramagnetic particles contained in a dry reagent on a disposable test card. We examined the deployment of this technology in decentralized hospital settings and compared test results obtained in the surgical intensive care unit, coronary care unit, and outpatient cardiology clinic with those obtained in the central laboratory. Nursing personnel were instructed in the use of the system, and quality control testing was performed daily by the laboratory staff. In the intensive care units, patient subjects included those on whom tests of prothrombin time and activated partial thromboplastin time had been ordered. Immediate determinations were performed by the intensive care unit nursing staff on the same citrated, whole-blood samples that were subsequently sent to the central laboratory. In the outpatient cardiology clinic, fingerstick blood samples were obtained for prothrombin time determinations with the dry chemistry system. Paired prothrombin time samples obtained by venipuncture were run in the hospital laboratory. The study involved multiple users, multiple locations, two lots of activated partial thromboplastin time cards, and several different instruments, over an extended period. Correlation coefficients between the dry chemistry system and the hospital laboratory under these conditions were in an acceptable range in all sites studied. We concluded that, with appropriate training and quality assurance, the dry chemistry system provides an acceptable alternative to the hospital laboratory for prothrombin time and activated partial thromboplastin time determinations. PMID:8503733

  15. 5 CFR 551.426 - Time spent in charitable activities.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 5 Administrative Personnel 1 2013-01-01 2013-01-01 false Time spent in charitable activities. 551.426 Section 551.426 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT CIVIL SERVICE REGULATIONS PAY ADMINISTRATION UNDER THE FAIR LABOR STANDARDS ACT Hours of Work Application of Principles...

  16. 5 CFR 551.426 - Time spent in charitable activities.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 5 Administrative Personnel 1 2012-01-01 2012-01-01 false Time spent in charitable activities. 551.426 Section 551.426 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT CIVIL SERVICE REGULATIONS PAY ADMINISTRATION UNDER THE FAIR LABOR STANDARDS ACT Hours of Work Application of Principles...

  17. 5 CFR 551.426 - Time spent in charitable activities.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 5 Administrative Personnel 1 2011-01-01 2011-01-01 false Time spent in charitable activities. 551.426 Section 551.426 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT CIVIL SERVICE REGULATIONS PAY ADMINISTRATION UNDER THE FAIR LABOR STANDARDS ACT Hours of Work Application of Principles...

  18. 5 CFR 551.426 - Time spent in charitable activities.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 5 Administrative Personnel 1 2014-01-01 2014-01-01 false Time spent in charitable activities. 551.426 Section 551.426 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT CIVIL SERVICE REGULATIONS PAY ADMINISTRATION UNDER THE FAIR LABOR STANDARDS ACT Hours of Work Application of Principles...

  19. Physical Activity in High School during "Free-Time" Periods

    ERIC Educational Resources Information Center

    Silva, Pedro; Sousa, Michael; Sá, Carla; Ribeiro, José; Mota, Jorge

    2015-01-01

    The purpose of this study was to examine youth physical activity (PA) in free-time periods during high school days and their contribution to total PA. Differences in terms of sex, age, body mass index and school level were assessed in a sample of Portuguese adolescents. Participants totalled 213 (135 girls), aged 14.6 ± 1.7, from two different…

  20. Influence of computer work under time pressure on cardiac activity.

    PubMed

    Shi, Ping; Hu, Sijung; Yu, Hongliu

    2015-03-01

    Computer users are often under stress when required to complete computer work within a required time. Work stress has repeatedly been associated with an increased risk for cardiovascular disease. The present study examined the effects of time pressure workload during computer tasks on cardiac activity in 20 healthy subjects. Heart rate, time domain and frequency domain indices of heart rate variability (HRV) and Poincaré plot parameters were compared among five computer tasks and two rest periods. Faster heart rate and decreased standard deviation of R-R interval were noted in response to computer tasks under time pressure. The Poincaré plot parameters showed significant differences between different levels of time pressure workload during computer tasks, and between computer tasks and the rest periods. In contrast, no significant differences were identified for the frequency domain indices of HRV. The results suggest that the quantitative Poincaré plot analysis used in this study was able to reveal the intrinsic nonlinear nature of the autonomically regulated cardiac rhythm. Specifically, heightened vagal tone occurred during the relaxation computer tasks without time pressure. In contrast, the stressful computer tasks with added time pressure stimulated cardiac sympathetic activity.

  1. Discretionary time among older adults: how do physical activity promotion interventions affect sedentary and active behaviors?

    PubMed

    Lee, Rebecca E; King, Abby C

    2003-01-01

    Investigation goals were to document discretionary time activities among older adults, determine whether time spent in discretionary activities varied by gender, and investigate whether participation in a prescribed physical activity (P) intervention increased the time that older adults spend in discretionary time physical activities that were not specifically prescribed by interventions. Longitudinal data were drawn from 2 published studies of older adults. Study 1 compared 2 PA interventions in healthy older men and women (N = 103, M =70.2 years), and Study 2 compared a PA intervention with a nutrition intervention in healthy older women (N =93, M =63.1 years). Participants in both studies completed similar assessments of their discretionary time activities using the Community Healthy Activities Model Program for Seniors questionnaire. Across both studies, at baseline, over 95% of participants reported talking on the telephone and reading as frequent sedentary discretionary time activities; over 80% reported visiting with friends and watching television or listening to the radio. Women engaged in significantly greater hours of social activities and household maintenance activities than did men (p <.05). From baseline to 12-month posttest, social, recreational, and household activities remained stable by gender and across time after participating in a PA intervention. Despite previously documented 2- to 3-hr increases in physical activities occurring in response to the study interventions, increases did not generalize for most participants to activities not prescribed by the intervention. Older adults are participating in numerous sedentary social and recreational activities that appear to remain stable across time and in the face of PA intervention prescriptions. PMID:12704013

  2. Privileging physical activity over healthy eating: 'Time' to Choose?

    PubMed

    Chircop, Andrea; Shearer, Cindy; Pitter, Robert; Sim, Meaghan; Rehman, Laurene; Flannery, Meredith; Kirk, Sara

    2015-09-01

    Physical activity and healthy eating have long been promoted as key strategies in tackling the 'wicked problem' of obesity. Both practices are assumed to go hand-in-hand, but whether one dominates the other has largely remained unexamined. Moreover, time, a dimension beyond the socio-ecological model, is a critical factor of families' busy lives, but related challenges are rarely articulated. We conducted 47 family interviews as part of a mixed methods study examining environmental influences on youth obesity in Nova Scotia, Eastern Canada. Participants were recruited from six schools at the junior high school level (grades 7-9; age range 12-14 years) based on location (urban, suburban and rural) and neighborhood socioeconomic status (high and low socioeconomic status). Time pressure to meet the demands associated with scheduled physical activity for youth was the dominant theme across interviews from all neighborhoods. Physical activity and healthy eating were valued differently, with greater value placed on physical activity than healthy eating. The pressure to engage youth in organized physical activity appeared to outweigh the importance of healthy eating, which led to neglecting family meals at home and consuming fast food and take out options. Our findings further reinforce the need to move beyond the socio-ecological model and integrate critical dimensions such as 'time', its challenges and opportunities, to allow for a more nuanced understanding of contemporary healthy living. It appears 'timely' to focus on healthy public policy in support of families, instead of unwittingly supporting a fast food industry that profits from time-pressured families.

  3. Full Time Course Kinetics of the Streptokinase-Plasminogen Activation Pathway*

    PubMed Central

    Nolan, Miranda; Bouldin, Samantha D.; Bock, Paul E.

    2013-01-01

    Our previously hypothesized mechanism for the pathway of plasminogen (Pg) activation by streptokinase (SK) was tested by the use of full time course kinetics. Three discontinuous chromogenic substrate initial rate assays were developed with different quenching conditions that enabled quantitation of the time courses of Pg depletion, plasmin (Pm) formation, transient formation of the conformationally activated SK·Pg* catalytic complex intermediate, formation of the SK·Pm catalytic complex, and the free concentrations of Pg, Pm, and SK. Analysis of full time courses of Pg activation by five concentrations of SK along with activity-based titrations of SK·Pg* and SK·Pm formation yielded rate and dissociation constants within 2-fold of those determined previously by continuous measurement of parabolic chromogenic substrate hydrolysis and fluorescence-based equilibrium binding. The results obtained with orthogonal assays provide independent support for a mechanism in which the conformationally activated SK·Pg* complex catalyzes an initial cycle of Pg proteolytic conversion to Pm that acts as a trigger. Higher affinity binding of the formed Pm to SK outcompetes Pg binding, terminating the trigger cycle and initiating the bullet catalytic cycle by the SK·Pm complex that converts the residual Pg into Pm. The new assays can be adapted to quantitate SK-Pg activation in the context of SK- or Pg-directed inhibitors, effectors, and SK allelic variants. To support this, we show for the first time with an assay specific for SK·Pg* that fibrinogen forms a ternary SK·Pg*·fibrinogen complex, which assembles with 200-fold enhanced SK·Pg* affinity, signaled by a perturbation of the SK·Pg* active site. PMID:23970549

  4. Analysis of time-resolved interaction force mode AFM imaging using active and passive probes.

    PubMed

    Giray Oral, Hasan; Parlak, Zehra; Levent Degertekin, F

    2012-09-01

    We present an in-depth analysis of time-resolved interaction force (TRIF) mode imaging for atomic force microscopy (AFM). A nonlinear model of an active AFM probe, performing simultaneous topography and material property imaging on samples with varying elasticity and adhesion is implemented in Simulink®. The model is capable of simulating various imaging modes, probe structures, sample material properties, tip-sample interaction force models, and actuation and feedback schemes. For passive AFM cantilevers, the model is verified by comparing results from the literature. As an example of an active probe, the force sensing integrated readout and active tip (FIRAT) probe is used. Simulation results indicate that the active and damped nature of FIRAT provides a significant level of control over the force applied to the sample, minimizing sample indentation and topography error. Active tip control (ATC) preserves constant contact time during force control for stable contact while preventing the loss of material property information such as elasticity and adhesive force. Simulation results are verified by TRIF mode imaging of the samples with both soft and stiff regions. PMID:22813887

  5. Monetary cost for time spent in everyday physical activities.

    PubMed

    Hsu, Anne S; Vlaev, Ivo

    2014-05-01

    We measured utility curves for the hypothetical monetary costs as a function of time engaged in three everyday physical activities: walking, standing, and sitting. We found that activities requiring more physical exertion resulted in steeper discount curves, i.e., perceived cost as a function of time. We also examined the effects of gain vs. loss framing (whether the activity brought additional rewards or prevented losses) as well as the effects of the individual factors of gender, income, and BMI. Steeper discount curves were associated with higher income (annual household ≥ median of $45,000) and gain framing (which indicates loss aversion). There were interactions between gender and frame, and also income and frame: Females and higher income participants showed loss aversion whereas males and lower income participants were not affected by framing. Males showed less discounting in gain frames relative to females, whereas females showed less discounting in loss frames relative to males. In gain frames, higher income participants discounted more but in loss frames there was no effect of income. We also found individual tendencies for discounting across activities: if an individual exhibited steeper discounting for one activity, they were also more likely to exhibit steeper discounting for the other activities. These results have implications for designers of interventions to encourage non-exercise physical activities, suggesting that loss-framed incentives are more effective for women and those with middle class (or greater) incomes. Furthermore loss framed incentives have more uniform impact across income brackets because people discount loss frames similarly regardless of income whereas those with middle-class incomes are not as motivated by gain frames. Our results also demonstrate a general method for examining the costs of effort associated with everyday activities. PMID:24632051

  6. Monetary cost for time spent in everyday physical activities.

    PubMed

    Hsu, Anne S; Vlaev, Ivo

    2014-05-01

    We measured utility curves for the hypothetical monetary costs as a function of time engaged in three everyday physical activities: walking, standing, and sitting. We found that activities requiring more physical exertion resulted in steeper discount curves, i.e., perceived cost as a function of time. We also examined the effects of gain vs. loss framing (whether the activity brought additional rewards or prevented losses) as well as the effects of the individual factors of gender, income, and BMI. Steeper discount curves were associated with higher income (annual household ≥ median of $45,000) and gain framing (which indicates loss aversion). There were interactions between gender and frame, and also income and frame: Females and higher income participants showed loss aversion whereas males and lower income participants were not affected by framing. Males showed less discounting in gain frames relative to females, whereas females showed less discounting in loss frames relative to males. In gain frames, higher income participants discounted more but in loss frames there was no effect of income. We also found individual tendencies for discounting across activities: if an individual exhibited steeper discounting for one activity, they were also more likely to exhibit steeper discounting for the other activities. These results have implications for designers of interventions to encourage non-exercise physical activities, suggesting that loss-framed incentives are more effective for women and those with middle class (or greater) incomes. Furthermore loss framed incentives have more uniform impact across income brackets because people discount loss frames similarly regardless of income whereas those with middle-class incomes are not as motivated by gain frames. Our results also demonstrate a general method for examining the costs of effort associated with everyday activities.

  7. The Timing of Noise-Sensitive Activities in Residential Areas

    NASA Technical Reports Server (NTRS)

    Fields, J. M.

    1985-01-01

    Data from a nationally representative survey of time use was analyzed to provide estimates of the percentage of the population which is engaged in noise sensitive activities during each hour of the day on weekdays, Fridays, Saturdays and Sundays. Estimates are provided of the percentage engaged in aural communication activities at home, sleeping at home, or simply at home. The day can be roughly divided into four noise sensitivity periods consisting of two relatively steady state periods, night and day and the early morning and evening transition periods. Weekends differ from weekdays in that the morning transition period is one hour later and the numbers of people engaged in aural communication during the day at home are approximately one-half to three-quarters greater. The extent and timing of noise sensitive activities was found to be similiar for all parts of the United States, for different sizes of urban areas, and for the three seasons surveyed (September through May). The timing of activity periods does not differ greatly by sex or age even though women and people over 65 are much more likely to be at home during the daytime.

  8. Dynamics of hippocampal ensemble activity realignment: time versus space.

    PubMed

    Redish, A D; Rosenzweig, E S; Bohanick, J D; McNaughton, B L; Barnes, C A

    2000-12-15

    Whether hippocampal map realignment is coupled more strongly to position or time was studied in rats trained to shuttle on a linear track. The rats were required to run from a start box and to pause at a goal location at a fixed location relative to stable distal cues (room-aligned coordinate frame). The origin of each lap was varied by shifting the start box and track as a unit (box-aligned coordinate frame) along the direction of travel. As observed by Gothard et al. (1996a), on each lap the hippocampal activity realigned from a representation that was box-aligned to one that was room-aligned. We studied the dynamics of this transition using a measure of how well the moment-by-moment ensemble activity matched the expected activity given the location of the animal in each coordinate frame. The coherency ratio, defined as the ratio of the matches for the two coordinate systems, provides a quantitative measure of the ensemble activity alignment and was used to compare four possible descriptions of the realignment process. The elapsed time since leaving the box provided a better predictor of the occurrence of the transition than any of the three spatial parameters investigated, suggesting that the shift between coordinate systems is at least partially governed by a stochastic, time-dependent process.

  9. The timing of noise-sensitive activities in residential areas

    NASA Astrophysics Data System (ADS)

    Fields, J. M.

    1985-07-01

    Data from a nationally representative survey of time use was analyzed to provide estimates of the percentage of the population which is engaged in noise sensitive activities during each hour of the day on weekdays, Fridays, Saturdays and Sundays. Estimates are provided of the percentage engaged in aural communication activities at home, sleeping at home, or simply at home. The day can be roughly divided into four noise sensitivity periods consisting of two relatively steady state periods, night and day and the early morning and evening transition periods. Weekends differ from weekdays in that the morning transition period is one hour later and the numbers of people engaged in aural communication during the day at home are approximately one-half to three-quarters greater. The extent and timing of noise sensitive activities was found to be similiar for all parts of the United States, for different sizes of urban areas, and for the three seasons surveyed (September through May). The timing of activity periods does not differ greatly by sex or age even though women and people over 65 are much more likely to be at home during the daytime.

  10. Real-time transposable element activity in individual live cells.

    PubMed

    Kim, Neil H; Lee, Gloria; Sherer, Nicholas A; Martini, K Michael; Goldenfeld, Nigel; Kuhlman, Thomas E

    2016-06-28

    The excision and reintegration of transposable elements (TEs) restructure their host genomes, generating cellular diversity involved in evolution, development, and the etiology of human diseases. Our current knowledge of TE behavior primarily results from bulk techniques that generate time and cell ensemble averages, but cannot capture cell-to-cell variation or local environmental and temporal variability. We have developed an experimental system based on the bacterial TE IS608 that uses fluorescent reporters to directly observe single TE excision events in individual cells in real time. We find that TE activity depends upon the TE's orientation in the genome and the amount of transposase protein in the cell. We also find that TE activity is highly variable throughout the lifetime of the cell. Upon entering stationary phase, TE activity increases in cells hereditarily predisposed to TE activity. These direct observations demonstrate that real-time live-cell imaging of evolution at the molecular and individual event level is a powerful tool for the exploration of genome plasticity in stressed cells. PMID:27298350

  11. Real-time transposable element activity in individual live cells

    PubMed Central

    Lee, Gloria; Martini, K. Michael

    2016-01-01

    The excision and reintegration of transposable elements (TEs) restructure their host genomes, generating cellular diversity involved in evolution, development, and the etiology of human diseases. Our current knowledge of TE behavior primarily results from bulk techniques that generate time and cell ensemble averages, but cannot capture cell-to-cell variation or local environmental and temporal variability. We have developed an experimental system based on the bacterial TE IS608 that uses fluorescent reporters to directly observe single TE excision events in individual cells in real time. We find that TE activity depends upon the TE’s orientation in the genome and the amount of transposase protein in the cell. We also find that TE activity is highly variable throughout the lifetime of the cell. Upon entering stationary phase, TE activity increases in cells hereditarily predisposed to TE activity. These direct observations demonstrate that real-time live-cell imaging of evolution at the molecular and individual event level is a powerful tool for the exploration of genome plasticity in stressed cells. PMID:27298350

  12. Using online lectures to make time for active learning.

    PubMed

    Prunuske, Amy J; Batzli, Janet; Howell, Evelyn; Miller, Sarah

    2012-09-01

    To make time in class for group activities devoted to critical thinking, we integrated a series of short online lectures into the homework assignments of a large, introductory biology course at a research university. The majority of students viewed the online lectures before coming to class and reported that the online lectures helped them to complete the in-class activity and did not increase the amount of time they devoted to the course. In addition, students who viewed the online lecture performed better on clicker questions designed to test lower-order cognitive skills. The in-class activities then gave the students practice analyzing the information in groups and provided the instructor with feedback about the students' understanding of the material. On the basis of the results of this study, we support creating hybrid course models that allow students to learn the fundamental information outside of class time, thereby creating time during the class period to be dedicated toward the conceptual understanding of the material.

  13. On the Khinchin Constant

    NASA Technical Reports Server (NTRS)

    Bailey, David H.; Borwein, Jonathan M.; Crandall, Richard E.; Craw, James M. (Technical Monitor)

    1995-01-01

    We prove known identities for the Khinchin constant and develop new identities for the more general Hoelder mean limits of continued fractions. Any of these constants can be developed as a rapidly converging series involving values of the Riemann zeta function and rational coefficients. Such identities allow for efficient numerical evaluation of the relevant constants. We present free-parameter, optimizable versions of the identities, and report numerical results.

  14. Studies in the system MgO-SiO2-CO2-H2O(I): The activity-product constant of chrysotile

    USGS Publications Warehouse

    Hostetler, P.B.; Christ, C.L.

    1968-01-01

    Chrysotile dissolves congruently in water according to the reaction: Mg3Si2O6(OH)4c + 5H2Ol = 3Mgaq2+ + 6OHaq- + 2H4SiO4aq. Experimental determination of the activity-product constant of chrysotile, Kchr = [Mg2+]3[OH-]6[H4SiO4aq]2, at 90??C, yields the value of Kchr = 10-49.2 ?? 100.5. A synthetic sample and a natural sample from New Idria, California, were used in the determination. Values of Kchr were calculated for temperatures ranging from 0??C to 200??C, using the thermochemical data of King et al. (1967) for chrysotile and antigorite, various solubility data for silica, and ionic partial molal heat capacities estimated by the method of criss and Cobble (1964a). Kchr is 10-54.1 at 0??C, rises to a maximum value of 10-48.5 at approximately 135??C, and is 10-49.1 at 200??C (all values for the three-phase system, chrysotile plus solution plus vapor). The calculated 90??C value is 10-49.1, in excellent agreement with the experimental value; for 25??C, the calculated value is 10-50.8. ?? 1968.

  15. Time-activity relationships to VOC personal exposure factors

    NASA Astrophysics Data System (ADS)

    Edwards, Rufus D.; Schweizer, Christian; Llacqua, Vito; Lai, Hak Kan; Jantunen, Matti; Bayer-Oglesby, Lucy; Künzli, Nino

    Social and demographic factors have been found to play a significant role in differences between time-activity patterns of population subgroups. Since time-activity patterns largely influence personal exposure to compounds as individuals move across microenvironments, exposure subgroups within the population may be defined by factors that influence daily activity patterns. Socio-demographic and environmental factors that define time-activity subgroups also define quantifiable differences in VOC personal exposures to different sources and individual compounds in the Expolis study. Significant differences in exposures to traffic-related compounds ethylbenzene, m- and p-xylene and o-xylene were observed in relation to gender, number of children and living alone. Categorization of exposures further indicated time exposed to traffic at work and time in a car as important determinants. Increased exposures to decane, nonane and undecane were observed for males, housewives and self-employed. Categorization of exposures indicated exposure subgroups related to workshop use and living downtown. Higher exposures to 3-carene and α-pinene commonly found in household cleaning products and fragrances were associated with more children, while exposures to traffic compounds ethylbenzene, m- and p-xylene and o-xylene were reduced with more children. Considerable unexplained variation remained in categorization of exposures associated with home product use and fragrances, due to individual behavior and product choice. More targeted data collection methods in VOC exposure studies for these sources should be used. Living alone was associated with decreased exposures to 2-methyl-1-propanol and 1-butanol, and traffic-related compounds. Identification of these subgroups may help to reduce the large amount of unexplained variation in VOC exposure studies. Further they may help in assessing impacts of urban planning that result in changes in behavior of individuals, resulting in shifts in

  16. Modified active disturbance rejection control for time-delay systems.

    PubMed

    Zhao, Shen; Gao, Zhiqiang

    2014-07-01

    Industrial processes are typically nonlinear, time-varying and uncertain, to which active disturbance rejection control (ADRC) has been shown to be an effective solution. The control design becomes even more challenging in the presence of time delay. In this paper, a novel modification of ADRC is proposed so that good disturbance rejection is achieved while maintaining system stability. The proposed design is shown to be more effective than the standard ADRC design for time-delay systems and is also a unified solution for stable, critical stable and unstable systems with time delay. Simulation and test results show the effectiveness and practicality of the proposed design. Linear matrix inequality (LMI) based stability analysis is provided as well.

  17. 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. PMID:17743107

  18. The cosmological constant

    NASA Technical Reports Server (NTRS)

    Carroll, Sean M.; Press, William H.; Turner, Edwin L.

    1992-01-01

    The cosmological constant problem is examined in the context of both astronomy and physics. Effects of a nonzero cosmological constant are discussed with reference to expansion dynamics, the age of the universe, distance measures, comoving density of objects, growth of linear perturbations, and gravitational lens probabilities. The observational status of the cosmological constant is reviewed, with attention given to the existence of high-redshift objects, age derivation from globular clusters and cosmic nuclear data, dynamical tests of Omega sub Lambda, quasar absorption line statistics, gravitational lensing, and astrophysics of distant objects. Finally, possible solutions to the physicist's cosmological constant problem are examined.

  19. Brain activity during interval timing depends on sensory structure.

    PubMed

    Pfeuty, Micha; Ragot, Richard; Pouthas, Viviane

    2008-04-14

    Precise timing is crucial for accurate perception and action in the range of hundreds of milliseconds. One still unresolved question concerns the influence of sensory information content on timing mechanisms. Numerous studies have converged to suggest that the CNV (Contingent Negative Variation), a slow negative wave that develops between two events, notably reflects temporal processing of the interval between these two events. The present study aimed at investigating CNV activity in duration discrimination tasks using either filled (continuous tones) or empty intervals (silent periods bounded by two brief tones). Participants had to compare a test duration with a 600-ms standard. Time perception was markedly better in the 'empty' than in the 'filled' condition. Electrophysiological analyses performed on the longest test duration (794 ms) of the comparison phase revealed an effect of the sensory structure on both the CNV amplitude and CNV time-course. The CNV amplitude was larger for filled than for empty intervals, suggesting a superimposition of timing-dependent activity and sensory sustained activity. Furthermore, the CNV time-course paralleled the temporal structure of the memorized sensory event: for filled intervals, the CNV amplitude stopped increasing at 600 ms, i.e. the expected end of the continuous tone; for empty intervals, in contrast, the CNV amplitude precisely increased at 600 ms, i.e. the expected onset of the second brief tone. These results suggest that the CNV reflects the mental rehearsal of the memorized sensory event, in line with the idea that temporal processing in the sub-second range is based on sensory information.

  20. YB-1 gene expression is kept constant during myocyte differentiation through replacement of different transcription factors and then falls gradually under the control of neural activity.

    PubMed

    Kobayashi, Shunsuke; Tanaka, Toru; Moue, Masamitsu; Ohashi, Sachiyo; Nishikawa, Taishi

    2015-11-01

    We have previously reported that translation of acetylcholine receptor α-subunit (AChR α) mRNA in skeletal muscle cells is regulated by Y-box binding protein 1 (YB-1) in response to neural activity, and that in the postnatal mouse developmental changes in the amount of YB-1 mRNA are similar to those of AChR α mRNA, which is known to be regulated by myogenic transcription factors. Here, we examined transcriptional regulation of the YB-1 gene in mouse skeletal muscle and differentiating C2C12 myocytes. Although neither YB-1 nor AChR α was detected at either the mRNA or protein level in adult hind limb muscle, YB-1 expression was transiently activated in response to denervation of the sciatic nerve and completely paralleled that of AChR α, suggesting that these genes are regulated by the same transcription factors. However, during differentiation of C2C12 cells to myotubes, the level of YB-1 remained constant even though the level of AChR α increased markedly. Reporter gene, gel mobility shift and ChIP assays revealed that in the initial stage of myocyte differentiation, transcription of the YB-1 gene was regulated by E2F1 and Sp1, and was then gradually replaced under the control of both MyoD and myogenin through an E-box sequence in the proximal region of the YB-1 gene promoter. These results suggest that transcription factors for the YB-1 gene are exchanged during skeletal muscle cell differentiation, perhaps playing a role in translational control of mRNAs by YB-1 in both myotube formation and the response of skeletal muscle tissues to neural stimulation.

  1. Time-Driven Activity-Based Costing in Emergency Medicine.

    PubMed

    Yun, Brian J; Prabhakar, Anand M; Warsh, Jonathan; Kaplan, Robert; Brennan, John; Dempsey, Kyle E; Raja, Ali S

    2016-06-01

    Value in emergency medicine is determined by both patient-important outcomes and the costs associated with achieving them. However, measuring true costs is challenging. Without an understanding of costs, emergency department (ED) leaders will be unable to determine which interventions might improve value for their patients. Although ongoing research may determine which outcomes are meaningful, an accurate costing system is also needed. This article reviews current costing mechanisms in the ED and their pitfalls. It then describes how time-driven activity-based costing may be superior to these current costing systems. Time-driven activity-based costing, in addition to being a more accurate costing system, can be used for process improvements in the ED. PMID:26365921

  2. Time-Driven Activity-Based Costing in Emergency Medicine.

    PubMed

    Yun, Brian J; Prabhakar, Anand M; Warsh, Jonathan; Kaplan, Robert; Brennan, John; Dempsey, Kyle E; Raja, Ali S

    2016-06-01

    Value in emergency medicine is determined by both patient-important outcomes and the costs associated with achieving them. However, measuring true costs is challenging. Without an understanding of costs, emergency department (ED) leaders will be unable to determine which interventions might improve value for their patients. Although ongoing research may determine which outcomes are meaningful, an accurate costing system is also needed. This article reviews current costing mechanisms in the ED and their pitfalls. It then describes how time-driven activity-based costing may be superior to these current costing systems. Time-driven activity-based costing, in addition to being a more accurate costing system, can be used for process improvements in the ED.

  3. Fundamental Physical Constants

    National Institute of Standards and Technology Data Gateway

    SRD 121 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.

  4. Calculation of magnetostriction constants

    NASA Astrophysics Data System (ADS)

    Tatebayashi, T.; Ohtsuka, S.; Ukai, T.; Mori, N.

    1986-02-01

    The magnetostriction constants h1 and h2 for Ni and Fe metals and the anisotropy constants K1 and K2 for Fe metal are calculated on the basis of the approximate d bands obtained by Deegan's prescription, by using Gilat-Raubenheimer's method. The obtained results are compared with the experimental ones.

  5. Muscle activation characteristics of the front leg during baseball swings with timing correction for sudden velocity decrease.

    PubMed

    Ohta, Yoichi; Nakamoto, Hiroki; Ishii, Yasumitsu; Ikudome, Sachi; Takahashi, Kyohei; Shima, Norihiro

    2014-01-01

    This study aimed to clarify the activation characteristics of the vastus lateralis muscle in the front leg during timing correction for a sudden decrease in the velocity of a target during baseball swings. Eleven male collegiate baseball players performed coincident timing tasks that comprised constant velocity of 8 m/s (unchanged) and a sudden decrease in velocity from 8 to 4 m/s (decreased velocity). Electromyography (EMG) revealed that the muscle activation was typically monophasic when responding unchanged conditions. The type of muscle activation during swings in response to decreased velocity condition was both monophasic and biphasic. When biphasic activation appeared in response to decreased velocity, the impact time and the time to peak EMG amplitude were significantly prolonged and the timing error was significantly smaller than that of monophasic activation. However, the EMG onset from the target start was consistent both monophasic and biphasic activation in response to conditions of decreased velocity. In addition, batters with small timing errors in response to decreased velocity were more likely to generate biphasic EMG activation. These findings indicated that timing correction for a sudden decrease in the velocity of an oncoming target is achieved by modifying the muscle activation characteristics of the vastus lateralis muscle of front leg from monophasic to biphasic to delay reaching peak muscle activation and thus prolong impact time. Therefore, the present findings suggests that the extent of timing errors in response to decreased velocity is influenced by the ability to correct muscle activation after its initiation rather than by delaying the initiation timing of muscle activation during baseball swings.

  6. Muscle activation characteristics of the front leg during baseball swings with timing correction for sudden velocity decrease.

    PubMed

    Ohta, Yoichi; Nakamoto, Hiroki; Ishii, Yasumitsu; Ikudome, Sachi; Takahashi, Kyohei; Shima, Norihiro

    2014-01-01

    This study aimed to clarify the activation characteristics of the vastus lateralis muscle in the front leg during timing correction for a sudden decrease in the velocity of a target during baseball swings. Eleven male collegiate baseball players performed coincident timing tasks that comprised constant velocity of 8 m/s (unchanged) and a sudden decrease in velocity from 8 to 4 m/s (decreased velocity). Electromyography (EMG) revealed that the muscle activation was typically monophasic when responding unchanged conditions. The type of muscle activation during swings in response to decreased velocity condition was both monophasic and biphasic. When biphasic activation appeared in response to decreased velocity, the impact time and the time to peak EMG amplitude were significantly prolonged and the timing error was significantly smaller than that of monophasic activation. However, the EMG onset from the target start was consistent both monophasic and biphasic activation in response to conditions of decreased velocity. In addition, batters with small timing errors in response to decreased velocity were more likely to generate biphasic EMG activation. These findings indicated that timing correction for a sudden decrease in the velocity of an oncoming target is achieved by modifying the muscle activation characteristics of the vastus lateralis muscle of front leg from monophasic to biphasic to delay reaching peak muscle activation and thus prolong impact time. Therefore, the present findings suggests that the extent of timing errors in response to decreased velocity is influenced by the ability to correct muscle activation after its initiation rather than by delaying the initiation timing of muscle activation during baseball swings. PMID:25918848

  7. Muscle Activation Characteristics of the Front Leg During Baseball Swings with Timing Correction for Sudden Velocity Decrease

    PubMed Central

    Ohta, Yoichi; Nakamoto, Hiroki; Ishii, Yasumitsu; Ikudome, Sachi; Takahashi, Kyohei; Shima, Norihiro

    2015-01-01

    This study aimed to clarify the activation characteristics of the vastus lateralis muscle in the front leg during timing correction for a sudden decrease in the velocity of a target during baseball swings. Eleven male collegiate baseball players performed coincident timing tasks that comprised constant velocity of 8 m/s (unchanged) and a sudden decrease in velocity from 8 to 4 m/s (decreased velocity). Electromyography (EMG) revealed that the muscle activation was typically monophasic when responding unchanged conditions. The type of muscle activation during swings in response to decreased velocity condition was both monophasic and biphasic. When biphasic activation appeared in response to decreased velocity, the impact time and the time to peak EMG amplitude were significantly prolonged and the timing error was significantly smaller than that of monophasic activation. However, the EMG onset from the target start was consistent both monophasic and biphasic activation in response to conditions of decreased velocity. In addition, batters with small timing errors in response to decreased velocity were more likely to generate biphasic EMG activation. These findings indicated that timing correction for a sudden decrease in the velocity of an oncoming target is achieved by modifying the muscle activation characteristics of the vastus lateralis muscle of front leg from monophasic to biphasic to delay reaching peak muscle activation and thus prolong impact time. Therefore, the present findings suggests that the extent of timing errors in response to decreased velocity is influenced by the ability to correct muscle activation after its initiation rather than by delaying the initiation timing of muscle activation during baseball swings. PMID:25918848

  8. Interevent time distributions of human multi-level activity in a virtual world

    NASA Astrophysics Data System (ADS)

    Mryglod, O.; Fuchs, B.; Szell, M.; Holovatch, Yu.; Thurner, S.

    2015-02-01

    Studying human behavior in virtual environments provides extraordinary opportunities for a quantitative analysis of social phenomena with levels of accuracy that approach those of the natural sciences. In this paper we use records of player activities in the massive multiplayer online game Pardus over 1238 consecutive days, and analyze dynamical features of sequences of actions of players. We build on previous work where temporal structures of human actions of the same type were quantified, and provide an empirical understanding of human actions of different types. This study of multi-level human activity can be seen as a dynamic counterpart of static multiplex network analysis. We show that the interevent time distributions of actions in the Pardus universe follow highly non-trivial distribution functions, from which we extract action-type specific characteristic 'decay constants'. We discuss characteristic features of interevent time distributions, including periodic patterns on different time scales, bursty dynamics, and various functional forms on different time scales. We comment on gender differences of players in emotional actions, and find that while males and females act similarly when performing some positive actions, females are slightly faster for negative actions. We also observe effects on the age of players: more experienced players are generally faster in making decisions about engaging in and terminating enmity and friendship, respectively.

  9. Real-Time Enzyme Kinetics by Quantitative NMR Spectroscopy and Determination of the Michaelis-Menten Constant Using the Lambert-W Function

    ERIC Educational Resources Information Center

    Her, Cheenou; Alonzo, Aaron P.; Vang, Justin Y.; Torres, Ernesto; Krishnan, V. V.

    2015-01-01

    Enzyme kinetics is an essential part of a chemistry curriculum, especially for students interested in biomedical research or in health care fields. Though the concept is routinely performed in undergraduate chemistry/biochemistry classrooms using other spectroscopic methods, we provide an optimized approach that uses a real-time monitoring of the…

  10. 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.

  11. Activity Time Budget during Foraging Trips of Emperor Penguins

    PubMed Central

    Watanabe, Shinichi; Sato, Katsufumi; Ponganis, Paul J.

    2012-01-01

    We developed an automated method using depth and one axis of body acceleration data recorded by animal-borne data loggers to identify activities of penguins over long-term deployments. Using this technique, we evaluated the activity time budget of emperor penguins (n = 10) both in water and on sea ice during foraging trips in chick-rearing season. During the foraging trips, emperor penguins alternated dive bouts (4.8±4.5 h) and rest periods on sea ice (2.5±2.3 h). After recorder deployment and release near the colony, the birds spent 17.9±8.4% of their time traveling until they reached the ice edge. Once at the ice edge, they stayed there more than 4 hours before the first dive. After the first dive, the mean proportions of time spent on the ice and in water were 30.8±7.4% and 69.2±7.4%, respectively. When in the water, they spent 67.9±3.1% of time making dives deeper than 5 m. Dive activity had no typical diurnal pattern for individual birds. While in the water between dives, the birds had short resting periods (1.2±1.7 min) and periods of swimming at depths shallower than 5 m (0.25±0.38 min). When the birds were on the ice, they primarily used time for resting (90.3±4.1% of time) and spent only 9.7±4.1% of time traveling. Thus, it appears that, during foraging trips at sea, emperor penguins traveled during dives >5 m depth, and that sea ice was primarily used for resting. Sea ice probably provides refuge from natural predators such as leopard seals. We also suggest that 24 hours of sunlight and the cycling of dive bouts with short rest periods on sea ice allow emperor penguins to dive continuously throughout the day during foraging trips to sea. PMID:23185608

  12. Limits on the time variation of the electromagnetic fine-structure constant in the low energy limit from absorption lines in the spectra of distant quasars.

    PubMed

    Srianand, R; Chand, H; Petitjean, P; Aracil, B

    2004-03-26

    We present the results of a detailed many-multiplet analysis performed on a new sample of Mg ii systems observed in high quality quasar spectra obtained using the Very Large Telescope. The weighted mean value of the variation in alpha derived from our analysis over the redshift range 0.4time of 9.7 Gyr in the most favored cosmological model today. This gives a 3sigma limit, -2.5 x 10(-16)time variation of alpha, that forms the strongest constraint obtained based on high redshift quasar absorption line systems.

  13. Integrated active sensor system for real time vibration monitoring

    PubMed Central

    Liang, Qijie; Yan, Xiaoqin; Liao, Xinqin; Cao, Shiyao; Lu, Shengnan; Zheng, Xin; Zhang, Yue

    2015-01-01

    We report a self-powered, lightweight and cost-effective active sensor system for vibration monitoring with multiplexed operation based on contact electrification between sensor and detected objects. The as-fabricated sensor matrix is capable of monitoring and mapping the vibration state of large amounts of units. The monitoring contents include: on-off state, vibration frequency and vibration amplitude of each unit. The active sensor system delivers a detection range of 0–60 Hz, high accuracy (relative error below 0.42%), long-term stability (10000 cycles). On the time dimension, the sensor can provide the vibration process memory by recording the outputs of the sensor system in an extend period of time. Besides, the developed sensor system can realize detection under contact mode and non-contact mode. Its high performance is not sensitive to the shape or the conductivity of the detected object. With these features, the active sensor system has great potential in automatic control, remote operation, surveillance and security systems. PMID:26538293

  14. Integrated active sensor system for real time vibration monitoring.

    PubMed

    Liang, Qijie; Yan, Xiaoqin; Liao, Xinqin; Cao, Shiyao; Lu, Shengnan; Zheng, Xin; Zhang, Yue

    2015-11-05

    We report a self-powered, lightweight and cost-effective active sensor system for vibration monitoring with multiplexed operation based on contact electrification between sensor and detected objects. The as-fabricated sensor matrix is capable of monitoring and mapping the vibration state of large amounts of units. The monitoring contents include: on-off state, vibration frequency and vibration amplitude of each unit. The active sensor system delivers a detection range of 0-60 Hz, high accuracy (relative error below 0.42%), long-term stability (10000 cycles). On the time dimension, the sensor can provide the vibration process memory by recording the outputs of the sensor system in an extend period of time. Besides, the developed sensor system can realize detection under contact mode and non-contact mode. Its high performance is not sensitive to the shape or the conductivity of the detected object. With these features, the active sensor system has great potential in automatic control, remote operation, surveillance and security systems.

  15. Influence of short-time imidacloprid and acetamiprid application on soil microbial metabolic activity and enzymatic activity.

    PubMed

    Wang, Fei; Yao, Jun; Chen, Huilun; Yi, Zhengji; Choi, Martin M F

    2014-09-01

    The influence of two neonicotinoids, i.e., imidacloprid (IMI) and acetamiprid (ACE), on soil microbial activities was investigated in a short period of time using a combination of the microcalorimetric approach and enzyme tests. Thermodynamic parameters such as Q T (J g(-1) soil), ∆H met (kJ mol(-1)), J Q/S (J g(-1) h(-1)), k (h(-1)), and soil enzymatic activities, dehydrogenase, phosphomonoesterase, arginine deaminase, and urease, were used to evaluate whole metabolic activity changes and acute toxicity following IMI and ACE treatment. Various profiles of thermogenic curves reflect different soil microbial activities. The microbial growth rate constant k, total heat evolution Q T (expect for IMI), and inhibitory ratio I show linear relationship with the doses of IMI and ACE. Q T for IMI increases at 0.0-20 μg g(-1) and then decreases at 20-80 μg g(-1), possibly attributing to the presence of tolerant microorganisms. The 50 % inhibitory ratios (IC50) of IMI and ACE are 95.7 and 77.2 μg g(-1), respectively. ACE displays slightly higher toxicity than IMI. Plots of k and Q T against microbial biomass-C indicate that the k and Q T are growth yield-dependent. IMI and ACE show 29.6; 40.4 and 23.0; and 23.3, 21.7, and 30.5 % inhibition of dehydrogenase, phosphomonoesterase, and urease activity, respectively. By contrast, the arginine deaminase activity is enhanced by 15.2 and 13.2 % with IMI and ACE, respectively. The parametric indices selected give a quantitative dose-response relationship of both insecticides and indicate that ACE is more toxic than IMI due to their difference in molecular structures. PMID:24819438

  16. Time delay between cardiac and brain activity during sleep transitions

    NASA Astrophysics Data System (ADS)

    Long, Xi; Arends, Johan B.; Aarts, Ronald M.; Haakma, Reinder; Fonseca, Pedro; Rolink, Jérôme

    2015-04-01

    Human sleep consists of wake, rapid-eye-movement (REM) sleep, and non-REM (NREM) sleep that includes light and deep sleep stages. This work investigated the time delay between changes of cardiac and brain activity for sleep transitions. Here, the brain activity was quantified by electroencephalographic (EEG) mean frequency and the cardiac parameters included heart rate, standard deviation of heartbeat intervals, and their low- and high-frequency spectral powers. Using a cross-correlation analysis, we found that the cardiac variations during wake-sleep and NREM sleep transitions preceded the EEG changes by 1-3 min but this was not the case for REM sleep transitions. These important findings can be further used to predict the onset and ending of some sleep stages in an early manner.

  17. Time-frequency analysis of rhythmic masticatory muscle activity.

    PubMed

    Farella, Mauro; Palla, Sandro; Gallo, Luigi Maria

    2009-06-01

    The aim of this study was to develop and validate under laboratory conditions an algorithm for a time-frequency analysis of rhythmic masticatory muscle activity (RMMA). The algorithm baseband demodulated the electromyographic (EMG) signal to provide a frequency versus time representation. Using appropriate thresholds for frequency and power parameters, it was possible to automatically assess the features of RMMA without examiner interaction. The algorithm was first tested using synthetic EMG signals and then using real EMG signals obtained from the masticatory muscles of 11 human subjects who underwent well-defined rhythmic, static, and possible confounding oral tasks. The accuracy of detection was quantified by receiver operating characteristics (ROC) curves. Sensitivity and specificity values were > or =90% and > or =96%, respectively. The areas under the ROC curves were > or =95% (standard error +/-0.1%). The proposed approach represents a promising tool to effectively investigate rhythmical contractions of the masticatory muscles.

  18. SMART: a system supporting medical activities in real-time.

    PubMed

    Pisanelli, D M; Consorti, F; Merialdo, P

    1997-01-01

    This paper describes the system SMART whose goal is real-time assistance to physicians who execute diagnostic or therapeutic protocols in a clinical context. SMART is able to retrieve a protocol from its knowledge base and to monitor its execution step by step for a single patient. Different protocols for different patients can be followed at the same time in a health care structure. The prototype realized supports the execution of protocols for evaluating surgical risks. It has been implemented according to the specifications given by the 4th Surgical Clinic of "Policlinico Umberto I" and reflects the activities actually performed in that hospital. However, the protocol model defined is general purpose and we envisage an easy application to other contexts and therefore to the informatization of other protocols.

  19. Time Dependence of Joy's Law for Emerging Active Regions

    NASA Astrophysics Data System (ADS)

    Chintzoglou, Georgios; Zhang, J.; Liu, Y.

    2013-07-01

    Joy's law governs the tilt of Active Regions (ARs) with respect to their absolute heliographic latitude. Together with Hale's law of hemispheric polarity, it is essential in constraining solar dynamo models. However, previous studies on Joy's law show only a weak positive trend between AR tilt angles and latitudes. In this study, we are focusing on the time dependence of Joy's law, for the cases of emerging ARs of Solar Cycle 24. We selected 40 ARs that emerge on the East hemisphere, effectively maximizing the observing time for each AR. Then, by converting the helioprojective maps into heliographic, we determine the geometrical as well as the magnetic-flux-weighted centroids for each emergence case. That way we are able to track the temporal evolution of their physical properties, including locations, fluxes of positive and negative polarities, as well as the tilt angles of these regions in a continuous manner until emergence stops and the ARs assume their final state.

  20. 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.

  1. The cosmological constant problem

    SciTech Connect

    Dolgov, A.D.

    1989-05-01

    A review of the cosmological term problem is presented. Baby universe model and the compensating field model are discussed. The importance of more accurate data on the Hubble constant and the Universe age is stressed. 18 refs.

  2. Philicities, Fugalities, and Equilibrium Constants.

    PubMed

    Mayr, Herbert; Ofial, Armin R

    2016-05-17

    The mechanistic model of Organic Chemistry is based on relationships between rate and equilibrium constants. Thus, strong bases are generally considered to be good nucleophiles and poor nucleofuges. Exceptions to this rule have long been known, and the ability of iodide ions to catalyze nucleophilic substitutions, because they are good nucleophiles as well as good nucleofuges, is just a prominent example for exceptions from the general rule. In a reaction series, the Leffler-Hammond parameter α = δΔG(⧧)/δΔG° describes the fraction of the change in the Gibbs energy of reaction, which is reflected in the change of the Gibbs energy of activation. It has long been considered as a measure for the position of the transition state; thus, an α value close to 0 was associated with an early transition state, while an α value close to 1 was considered to be indicative of a late transition state. Bordwell's observation in 1969 that substituent variation in phenylnitromethanes has a larger effect on the rates of deprotonation than on the corresponding equilibrium constants (nitroalkane anomaly) triggered the breakdown of this interpretation. In the past, most systematic investigations of the relationships between rates and equilibria of organic reactions have dealt with proton transfer reactions, because only for few other reaction series complementary kinetic and thermodynamic data have been available. In this Account we report on a more general investigation of the relationships between Lewis basicities, nucleophilicities, and nucleofugalities as well as between Lewis acidities, electrophilicities, and electrofugalities. Definitions of these terms are summarized, and it is suggested to replace the hybrid terms "kinetic basicity" and "kinetic acidity" by "protophilicity" and "protofugality", respectively; in this way, the terms "acidity" and "basicity" are exclusively assigned to thermodynamic properties, while "philicity" and "fugality" refer to kinetics

  3. 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.

  4. Beyond the Hubble Constant

    NASA Astrophysics Data System (ADS)

    1995-08-01

    about the distances to galaxies and thereby about the expansion rate of the Universe. A simple way to determine the distance to a remote galaxy is by measuring its redshift, calculate its velocity from the redshift and divide this by the Hubble constant, H0. For instance, the measured redshift of the parent galaxy of SN 1995K (0.478) yields a velocity of 116,000 km/sec, somewhat more than one-third of the speed of light (300,000 km/sec). From the universal expansion rate, described by the Hubble constant (H0 = 20 km/sec per million lightyears as found by some studies), this velocity would indicate a distance to the supernova and its parent galaxy of about 5,800 million lightyears. The explosion of the supernova would thus have taken place 5,800 million years ago, i.e. about 1,000 million years before the solar system was formed. However, such a simple calculation works only for relatively ``nearby'' objects, perhaps out to some hundred million lightyears. When we look much further into space, we also look far back in time and it is not excluded that the universal expansion rate, i.e. the Hubble constant, may have been different at earlier epochs. This means that unless we know the change of the Hubble constant with time, we cannot determine reliable distances of distant galaxies from their measured redshifts and velocities. At the same time, knowledge about such change or lack of the same will provide unique information about the time elapsed since the Universe began to expand (the ``Big Bang''), that is, the age of the Universe and also its ultimate fate. The Deceleration Parameter q0 Cosmologists are therefore eager to determine not only the current expansion rate (i.e., the Hubble constant, H0) but also its possible change with time (known as the deceleration parameter, q0). Although a highly accurate value of H0 has still not become available, increasing attention is now given to the observational determination of the second parameter, cf. also the Appendix at the

  5. Henry's law constants of polyols

    NASA Astrophysics Data System (ADS)

    Compernolle, S.; Müller, J.-F.

    2014-05-01

    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. Depending on the case, infinite dilution activity coefficients (IDACs), solid state pressures or activity coefficient ratios are obtained as intermediary results. 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.

  6. Cardiac anisotropy: is it negligible regarding noninvasive activation time imaging?

    PubMed

    Modre, Robert; Seger, Michael; Fischer, Gerald; Hintermüller, Christoph; Hayn, Dieter; Pfeifer, Bernhard; Hanser, Friedrich; Schreier, Günter; Tilg, Bernhard

    2006-04-01

    The aim of this study was to quantify the effect of cardiac anisotropy in the activation-based inverse problem of electrocardiography. Differences of the patterns of simulated body surface potential maps for isotropic and anisotropic conditions were investigated with regard to activation time (AT) imaging of ventricular depolarization. AT maps were estimated by solving the nonlinear inverse ill-posed problem employing spatio-temporal regularization. Four different reference AT maps (sinus rhythm, right-ventricular and septal pacing, accessory pathway) were calculated with a bidomain theory based anisotropic finite-element heart model in combination with a cellular automaton. In this heart model a realistic fiber architecture and conduction system was implemented. Although the anisotropy has some effects on forward solutions, effects on inverse solutions are small indicating that cardiac anisotropy might be negligible for some clinical applications (e.g., imaging of focal events) of our AT imaging approach. The main characteristic events of the AT maps were estimated despite neglected electrical anisotropy in the inverse formulation. The worst correlation coefficient of the estimated AT maps was 0.810 in case of sinus rhythm. However, all characteristic events of the activation pattern were found. The results of this study confirm our clinical validation studies of noninvasive AT imaging in which cardiac anisotropy was neglected.

  7. Varying Fine-Structure Constant and the Cosmological Constant Problem

    NASA Astrophysics Data System (ADS)

    Fujii, Yasunori

    We start with a brief account of the latest analysis of the Oklo phenomenon providing the still most stringent constraint on time variability of the fine-structure constant α. Comparing this with the recent result from the measurement of distant QSO's appears to indicate a non-uniform time-dependence, which we argue to be related to another recent finding of the accelerating universe. This view is implemented in terms of the scalar-tensor theory, applied specifically to the small but nonzero cosmological constant. Our detailed calculation shows that these two phenomena can be understood in terms of a common origin, a particular behavior of the scalar field, dilaton. We also sketch how this theoretical approach makes it appropriate to revisit non-Newtonian gravity featuring small violation of Weak Equivalence Principle at medium distances.

  8. School playgrounds and physical activity policies as predictors of school and home time activity

    PubMed Central

    2011-01-01

    Background Previous work has suggested that the number of permanent play facilities in school playgrounds and school-based policies on physical activity can influence physical activity in children. However, few comparable studies have used objective measures of physical activity or have had little adjustment for multiple confounders. Methods Physical activity was measured by accelerometry over 5 recess periods and 3 full school days in 441 children from 16 primary schools in Dunedin, New Zealand. The number of permanent play facilities (swing, fort, slide, obstacle course, climbing wall etc) in each school playground was counted on three occasions by three researchers following a standardized protocol. Information on school policies pertaining to physical activity and participation in organized sport was collected by questionnaire. Results Measurement of school playgrounds proved to be reliable (ICC 0.89) and consistent over time. Boys were significantly more active than girls (P < 0.001), but little time overall was spent in moderate-vigorous physical activity (MVPA). Boys engaged in MVPA for 32 (SD 17) minutes each day of which 17 (10) took place at school compared with 23 (14) and 11 (7) minutes respectively in girls. Each additional 10-unit increase in play facilities was associated with 3.2% (95% CI 0.0-6.4%) more total activity and 8.3% (0.8-16.3%) more MVPA during recess. By contrast, school policy score was not associated with physical activity in children. Conclusion The number of permanent play facilities in school playgrounds is associated with higher physical activity in children, whereas no relationship was observed for school policies relating to physical activity. Increasing the number of permanent play facilities may offer a cost-effective long-term approach to increasing activity levels in children. PMID:21521530

  9. Infrared optical activity: electric field approaches in time domain.

    PubMed

    Rhee, Hanju; Choi, Jun-Ho; Cho, Minhaeng

    2010-12-21

    Vibrational circular dichroism (VCD) spectroscopy provides detailed information about the absolute configurations of chiral molecules including biomolecules and synthetic drugs. This method is the infrared (IR) analogue of the more popular electronic CD spectroscopy that uses the ultraviolet and visible ranges of the electromagnetic spectrum. Because conventional electronic CD spectroscopy measures the difference in signal intensity, problems such as weak signal and low time-resolution can limit its utility. To overcome the difficulties associated with that approach, we have recently developed femtosecond IR optical activity (IOA) spectrometry, which directly measures the IOA free-induction-decay (FID), the impulsive chiroptical IR response that occurs over time. In this Account, we review the time-domain electric field measurement and calculation methods used to simultaneously characterize VCD and related vibrational optical rotatory dispersion (VORD) spectra. Although conventional methods measure the electric field intensity, this vibrational technique is based on a direct phase-and-amplitude measurement of the electric field of the chiroptical signal over time. This method uses a cross-polarization analyzer to carry out heterodyned spectral interferometry. The cross-polarization scheme enables us to selectively remove the achiral background signal, which is the dominant noise component present in differential intensity measurement techniques. Because we can detect the IOA FID signal in a phase-amplitude-sensitive manner, we can directly characterize the time-dependent electric dipole/magnetic dipole response function and the complex chiral susceptibility that contain information about the angular oscillations of charged particles. These parameters yield information about the VCD and VORD spectra. In parallel with such experimental developments, we have also calculated the IOA FID signal and the resulting VCD spectrum. These simulations use a quantum mechanical

  10. Infrared optical activity: electric field approaches in time domain.

    PubMed

    Rhee, Hanju; Choi, Jun-Ho; Cho, Minhaeng

    2010-12-21

    Vibrational circular dichroism (VCD) spectroscopy provides detailed information about the absolute configurations of chiral molecules including biomolecules and synthetic drugs. This method is the infrared (IR) analogue of the more popular electronic CD spectroscopy that uses the ultraviolet and visible ranges of the electromagnetic spectrum. Because conventional electronic CD spectroscopy measures the difference in signal intensity, problems such as weak signal and low time-resolution can limit its utility. To overcome the difficulties associated with that approach, we have recently developed femtosecond IR optical activity (IOA) spectrometry, which directly measures the IOA free-induction-decay (FID), the impulsive chiroptical IR response that occurs over time. In this Account, we review the time-domain electric field measurement and calculation methods used to simultaneously characterize VCD and related vibrational optical rotatory dispersion (VORD) spectra. Although conventional methods measure the electric field intensity, this vibrational technique is based on a direct phase-and-amplitude measurement of the electric field of the chiroptical signal over time. This method uses a cross-polarization analyzer to carry out heterodyned spectral interferometry. The cross-polarization scheme enables us to selectively remove the achiral background signal, which is the dominant noise component present in differential intensity measurement techniques. Because we can detect the IOA FID signal in a phase-amplitude-sensitive manner, we can directly characterize the time-dependent electric dipole/magnetic dipole response function and the complex chiral susceptibility that contain information about the angular oscillations of charged particles. These parameters yield information about the VCD and VORD spectra. In parallel with such experimental developments, we have also calculated the IOA FID signal and the resulting VCD spectrum. These simulations use a quantum mechanical

  11. Variation of Fundamental Constants

    NASA Astrophysics Data System (ADS)

    Flambaum, V. V.

    2006-11-01

    Theories unifying gravity with other interactions suggest temporal and spatial variation of the fundamental ``constants'' in expanding Universe. The spatial variation can explain a fine tuning of the fundamental constants which allows humans (and any life) to appear. We appeared in the area of the Universe where the values of the fundamental constants are consistent with our existence. We present a review of recent works devoted to the variation of the fine structure constant α, strong interaction and fundamental masses. There are some hints for the variation in quasar absorption spectra. Big Bang nucleosynthesis, and Oklo natural nuclear reactor data. A very promising method to search for the variation of the fundamental constants consists in comparison of different atomic clocks. Huge enhancement of the variation effects happens in transition between accidentally degenerate atomic and molecular energy levels. A new idea is to build a ``nuclear'' clock based on the ultraviolet transition between very low excited state and ground state in Thorium nucleus. This may allow to improve sensitivity to the variation up to 10 orders of magnitude! Huge enhancement of the variation effects is also possible in cold atomic and molecular collisions near Feshbach resonance.

  12. Time Use Patterns between Maintenance, Subsistence and Leisure Activities: A Case Study in China

    ERIC Educational Resources Information Center

    Hui-fen, Zhou; Zhen-shan, Li; Dong-qian, Xue; Yang, Lei

    2012-01-01

    The Chinese government conducted its first time use survey of the activities of Chinese individuals in 2008. Activities were classified into three broad types, maintenance activities, subsistence activities and leisure activities. Time use patterns were defined by an individuals' time spent on maintenance, subsistence and leisure activities each…

  13. 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.

  14. On the precision of automated activation time estimation

    NASA Technical Reports Server (NTRS)

    Kaplan, D. T.; Smith, J. M.; Rosenbaum, D. S.; Cohen, R. J.

    1988-01-01

    We examined how the assignment of local activation times in epicardial and endocardial electrograms is affected by sampling rate, ambient signal-to-noise ratio, and sinx/x waveform interpolation. Algorithms used for the estimation of fiducial point locations included dV/dtmax, and a matched filter detection algorithm. Test signals included epicardial and endocardial electrograms overlying both normal and infarcted regions of dog myocardium. Signal-to-noise levels were adjusted by combining known data sets with white noise "colored" to match the spectral characteristics of experimentally recorded noise. For typical signal-to-noise ratios and sampling rates, the template-matching algorithm provided the greatest precision in reproducibly estimating fiducial point location, and sinx/x interpolation allowed for an additional significant improvement. With few restrictions, combining these two techniques may allow for use of digitization rates below the Nyquist rate without significant loss of precision.

  15. The Hubble constant

    NASA Technical Reports Server (NTRS)

    Huchra, John P.

    1992-01-01

    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 radial velocities and distances. Although there has been considerable progress in the 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.

  16. Optimal design of active and semi-active suspensions including time delays and preview

    NASA Astrophysics Data System (ADS)

    Hac', A.; Youn, I.

    1993-10-01

    Several control laws for active and semi-active suspension based on a linear half car model are derived and investigated. The strategies proposed take full advantage of the fact that the road input to the rear wheels is a delayed version of that to the front wheels, which in turn can be obtained either from the measurements of the front wheels and body motions or by direct preview of road irregularities if preview sensors are available. The suspension systems are optimized with respect to ride comfort, road holding and suspension rattle space as expressed by the mean-square-values of body acceleration (including effects of heave and pitch), tire deflections and front and rear suspension travels. The optimal control laws that minimize the given performance index and include passivity constraints in the semi-active case are derived using calculus of variation. The optimal semi-active suspension becomes piecewise linear, varying between passive and fully active systems and combinations of them. The performances of active and semi-active systems with and without preview were evaluated by numerical simulation in the time and frequency domains. The results show that incorporation of time delay between the front and rear axles in controller design improves the dynamic behavior of the rear axle and control of body pitch motion, while additional preview improves front wheel dynamics and body heave.

  17. Innovation diffusion on time-varying activity driven networks

    NASA Astrophysics Data System (ADS)

    Rizzo, Alessandro; Porfiri, Maurizio

    2016-01-01

    Since its introduction in the 1960s, the theory of innovation diffusion has contributed to the advancement of several research fields, such as marketing management and consumer behavior. The 1969 seminal paper by Bass [F.M. Bass, Manag. Sci. 15, 215 (1969)] introduced a model of product growth for consumer durables, which has been extensively used to predict innovation diffusion across a range of applications. Here, we propose a novel approach to study innovation diffusion, where interactions among individuals are mediated by the dynamics of a time-varying network. Our approach is based on the Bass' model, and overcomes key limitations of previous studies, which assumed timescale separation between the individual dynamics and the evolution of the connectivity patterns. Thus, we do not hypothesize homogeneous mixing among individuals or the existence of a fixed interaction network. We formulate our approach in the framework of activity driven networks to enable the analysis of the concurrent evolution of the interaction and individual dynamics. Numerical simulations offer a systematic analysis of the model behavior and highlight the role of individual activity on market penetration when targeted advertisement campaigns are designed, or a competition between two different products takes place.

  18. Activated partial thromboplastin time: new tricks for an old dogma.

    PubMed

    Lippi, Giuseppe; Favaloro, Emmanuel J

    2008-10-01

    The activated partial thromboplastin time (APTT) is the most common coagulation test procedure performed in routine laboratories, apart from the prothrombin time. The test is traditionally used for identifying quantitative and qualitative abnormalities in the intrinsic and common pathways of coagulation, monitoring anticoagulant therapy with unfractionated heparin, and detecting inhibitors of blood coagulation, the most common of which is the lupus anticoagulant. Whereas short APTT values have been mostly overlooked in the past, recent evidence suggests that these might be associated with hypercoagulability. Although clinical relevance is yet to be clearly defined, hypercoagulability detected by a shortened APTT appears to be significantly associated with a major risk of venous thromboembolism independently from other variables such as blood group, the presence of inherited thrombophilia, and factor VIII levels. This novel finding suggests that this traditional, simple, and inexpensive test might have renewed utility along with traditional thrombophilic tests in the evaluation of venous thromboembolic risk. In addition, APTT waveform analysis is also providing mounting evidence of added utility, in particular for identifying sepsis and disseminated intravascular coagulation in critically ill patients (particularly where this might worsen the prognosis), for monitoring therapy in patients with inhibitors, and as a diagnostic aid to identify patients with antiphospholipid antibodies. In total, such emerging evidence suggests that the APTT is either an old dogma displaying new tricks or else might describe a new dogma for an old laboratory trick. PMID:19085761

  19. Time-Resolved Spectroscopy of Active Binary Stars

    NASA Technical Reports Server (NTRS)

    Brown, Alexander

    2000-01-01

    This NASA grant covered EUVE observing and data analysis programs during EUVE Cycle 5 GO observing. The research involved a single Guest Observer project 97-EUVE-061 "Time-Resolved Spectroscopy of Active Binary Stars". The grant provided funding that covered 1.25 months of the PI's salary. The activities undertaken included observation planning and data analysis (both temporal and spectral). This project was awarded 910 ksec of observing time to study seven active binary stars, all but one of which were actually observed. Lambda-And was observed on 1997 Jul 30 - Aug 3 and Aug 7-14 for a total of 297 ksec; these observations showed two large complex flares that were analyzed by Osten & Brown (1999). AR Psc, observed for 350 ksec on 1997 Aug 27 - Sep 13, showed only relatively small flares that were also discussed by Osten & Brown (1999). EUVE observations of El Eri were obtained on 1994 August 24-28, simultaneous with ASCA X-ray spectra. Four flares were detected by EUVE with one of these also observed simultaneously, by ASCA. The other three EUVE observations were of the stars BY Dra (1997 Sep 22-28), V478 Lyr (1998 May 18-27), and sigma Gem (1998 Dec 10-22). The first two stars showed a few small flares. The sigma Gem data shows a beautiful complete flare with a factor of ten peak brightness compared to quiescence. The flare rise and almost all the decay phase are observed. Unfortunately no observations in other spectral regions were obtained for these stars. Analysis of the lambda-And and AR Psc observations is complete and the results were published in Osten & Brown (1999). Analysis of the BY Dra, V478 Lyr and sigma Gem EUVE data is complete and will be published in Osten (2000, in prep.). The El Eri EUV analysis is also completed and the simultaneous EUV/X-ray study will be published in Osten et al. (2000, in prep.). Both these latter papers will be submitted in summer 2000. All these results will form part of Rachel Osten's PhD thesis.

  20. Recess Activities of the Week (RAW): Promoting Free Time Physical Activity to Combat Childhood Obesity

    ERIC Educational Resources Information Center

    Sinclair, Christina D.; Stellino, Megan Babkes; Partidge, Julie A.

    2008-01-01

    Childhood obesity and inactivity levels among young Americans have risen steadily over the last few decades, and has become a major concern. Participation in regular physical activity helps prevent excess adiposity in children and youth. Recess is a regularly occurring period of time in school children's days which is an opportunity to help them…

  1. Influence of different anoxic time exposures on active biomass, protozoa and filamentous bacteria in activated sludge.

    PubMed

    Rodriguez-Perez, S; Fermoso, F G; Arnaiz, C

    2016-01-01

    Medium-sized wastewater treatment plants are considered too small to implement anaerobic digestion technologies and too large for extensive treatments. A promising option as a sewage sludge reduction method is the inclusion of anoxic time exposures. In the present study, three different anoxic time exposures of 12, 6 and 4 hours have been studied to reduce sewage sludge production. The best anoxic time exposure was observed under anoxic/oxic cycles of 6 hours, which reduced 29.63% of the biomass production compared with the oxic control conditions. The sludge under different anoxic time exposures, even with a lower active biomass concentration than the oxic control conditions, showed a much higher metabolic activity than the oxic control conditions. Microbiological results suggested that both protozoa density and abundance of filamentous bacteria decrease under anoxic time exposures compared to oxic control conditions. The anoxic time exposures 6/6 showed the highest reduction in both protozoa density, 37.5%, and abundance of filamentous bacteria, 41.1%, in comparison to the oxic control conditions. The groups of crawling ciliates, carnivorous ciliates and filamentous bacteria were highly influenced by the anoxic time exposures. Protozoa density and abundance of filamentous bacteria have been shown as promising bioindicators of biomass production reduction.

  2. Influence of different anoxic time exposures on active biomass, protozoa and filamentous bacteria in activated sludge.

    PubMed

    Rodriguez-Perez, S; Fermoso, F G; Arnaiz, C

    2016-01-01

    Medium-sized wastewater treatment plants are considered too small to implement anaerobic digestion technologies and too large for extensive treatments. A promising option as a sewage sludge reduction method is the inclusion of anoxic time exposures. In the present study, three different anoxic time exposures of 12, 6 and 4 hours have been studied to reduce sewage sludge production. The best anoxic time exposure was observed under anoxic/oxic cycles of 6 hours, which reduced 29.63% of the biomass production compared with the oxic control conditions. The sludge under different anoxic time exposures, even with a lower active biomass concentration than the oxic control conditions, showed a much higher metabolic activity than the oxic control conditions. Microbiological results suggested that both protozoa density and abundance of filamentous bacteria decrease under anoxic time exposures compared to oxic control conditions. The anoxic time exposures 6/6 showed the highest reduction in both protozoa density, 37.5%, and abundance of filamentous bacteria, 41.1%, in comparison to the oxic control conditions. The groups of crawling ciliates, carnivorous ciliates and filamentous bacteria were highly influenced by the anoxic time exposures. Protozoa density and abundance of filamentous bacteria have been shown as promising bioindicators of biomass production reduction. PMID:27508364

  3. XrayOpticsConstants

    2005-06-20

    This application (XrayOpticsConstants) is a tool for displaying X-ray and Optical properties for a given material, x-ray photon energy, and in the case of a gas, pressure. The display includes fields such as the photo-electric absorption attenuation length, density, material composition, index of refraction, and emission properties (for scintillator materials).

  4. Spots and Flares: Stellar Activity in the Time Domain Era

    NASA Astrophysics Data System (ADS)

    Davenport, James

    2015-08-01

    Time domain photometric surveys for large numbers of stars have ushered in a new era of statistical studies of astrophysics. This new parameter space allows us to observe how stars behave and change on a human timescale, and facilitates ensemble studies to understand how stars change over cosmic timescales. With current and planned time domain stellar surveys, we will be able to put the Sun in a Galactic context, and discover how typical or unique our parent star truly is. The goal of this thesis is to develop techniques for detecting and analyzing the most prominent forms of magnetic activity from low-mass stars in modern time domain surveys: starspots and flares. Magnetic field strength is a fundamental property that decays over a star's life. As a result, flux modulations from both flares and starspots become smaller amplitude and more infrequent in light curves. Methods for detecting these forms of magnetic activity will be extensible to future time domain surveys, and helpful in characterizing the properties of stars as they age. Flares can be detected in sparsely sampled wide field surveys by searching for bright single-point outliers in light curves. Using both red optical and near infrared data from ground-based surveys over many years, I have constrained the rate of flares in multiple wavelengths for an ensemble of M dwarfs. Studying flares in these existing ground-based datasets will enable predictions for future survey yields. Space-based photometry enables continuous and precise monitoring of stars for many years, which is crucial for obtaining a complete census of flares from a single star. Using 11 months of 1-minute photometry for the M dwarf GJ 1243, I have amassed over 6100 flare events, the largest sample of white light flares for any low-mass star. I have also created the first high fidelity empirical white light flare template, which shows three distinct phases in typical flare light curves. With this template, I demonstrate that complex multi

  5. Spots and Flares: Stellar Activity in the Time Domain Era

    NASA Astrophysics Data System (ADS)

    Davenport, James R. A.

    Time domain photometric surveys for large numbers of stars have ushered in a new era of statistical studies of astrophysics. This new parameter space allows us to observe how stars behave and change on a human timescale, and facilitates ensemble studies to understand how stars change over cosmic timescales. With current and planned time domain stellar surveys, we will be able to put the Sun in a Galactic context, and discover how typical or unique our parent star truly is. The goal of this thesis is to develop techniques for detecting and analyzing the most prominent forms of magnetic activity from low-mass stars in modern time domain surveys: starspots and flares. Magnetic field strength is a fundamental property that decays over a star's life. As a result, flux modulations from both flares and starspots become smaller amplitude and more infrequent in light curves. Methods for detecting these forms of magnetic activity will be extensible to future time domain surveys, and helpful in characterizing the properties of stars as they age. Flares can be detected in sparsely sampled wide field surveys by searching for bright single-point outliers in light curves. Using both red optical and near infrared data from ground-based surveys over many years, I have constrained the rate of flares in multiple wavelengths for an ensemble of M dwarfs. Studying flares in these existing ground-based datasets will enable predictions for future survey yields. Space-based photometry enables continuous and precise monitoring of stars for many years, which is crucial for obtaining a complete census of flares from a single star. Using 11 months of 1-minute photometry for the M dwarf GJ 1243, I have amassed over 6100 flare events, the largest sample of white light flares for any low-mass star. I have also created the first high fidelity empirical white light flare template, which shows three distinct phases in typical flare light curves. With this template, I demonstrate that complex multi

  6. Real-time Neural Network predictions of geomagnetic activity indices

    NASA Astrophysics Data System (ADS)

    Bala, R.; Reiff, P. H.

    2009-12-01

    The Boyle potential or the Boyle Index (BI), Φ (kV)=10-4 (V/(km/s))2 + 11.7 (B/nT) sin3(θ/2), is an empirically-derived formula that can characterize the Earth's polar cap potential, which is readily derivable in real time using the solar wind data from ACE (Advanced Composition Explorer). The BI has a simplistic form that utilizes a non-magnetic "viscous" and a magnetic "merging" component to characterize the magnetospheric behavior in response to the solar wind. We have investigated its correlation with two of conventional geomagnetic activity indices in Kp and the AE index. We have shown that the logarithms of both 3-hr and 1-hr averages of the BI correlate well with the subsequent Kp: Kp = 8.93 log10(BI) - 12.55 along with 1-hr BI correlating with the subsequent log10(AE): log10(AE) = 1.78 log10(BI) - 3.6. We have developed a new set of algorithms based on Artificial Neural Networks (ANNs) suitable for short term space weather forecasts with an enhanced lead-time and better accuracy in predicting Kp and AE over some leading models; the algorithms omit the time history of its targets to utilize only the solar wind data. Inputs to our ANN models benefit from the BI and its proven record as a forecasting parameter since its initiation in October, 2003. We have also performed time-sensitivity tests using cross-correlation analysis to demonstrate that our models are as efficient as those that incorporates the time history of the target indices in their inputs. Our algorithms can predict the upcoming full 3-hr Kp, purely from the solar wind data and achieve a linear correlation coefficient of 0.840, which means that it predicts the upcoming Kp value on average to within 1.3 step, which is approximately the resolution of the real-time Kp estimate. Our success in predicting Kp during a recent unexpected event (22 July ’09) is shown in the figure. Also, when predicting an equivalent "one hour Kp'', the correlation coefficient is 0.86, meaning on average a prediction

  7. Varying constant cosmologies and cosmic singularities

    NASA Astrophysics Data System (ADS)

    Dabrowski, Mariusz P.; Marosek, Konrad

    2013-02-01

    We review standard and non-standard cosmological singularities paying special attention onto those which are of a weak type and do not necessarily exhibit geodesic incompletness. Then, we discuss how these singularities can be weakened, strengthened, or avoided due to the time-variation of the physical constants such as the speed of light c and the gravitational constant G.

  8. Innovative techniques to analyze time series of geomagnetic activity indices

    NASA Astrophysics Data System (ADS)

    Balasis, Georgios; Papadimitriou, Constantinos; Daglis, Ioannis A.; Potirakis, Stelios M.; Eftaxias, Konstantinos

    2016-04-01

    Magnetic storms are undoubtedly among the most important phenomena in space physics and also a central subject of space weather. The non-extensive Tsallis entropy has been recently introduced, as an effective complexity measure for the analysis of the geomagnetic activity Dst index. The Tsallis entropy sensitively shows the complexity dissimilarity among different "physiological" (normal) and "pathological" states (intense magnetic storms). More precisely, the Tsallis entropy implies the emergence of two distinct patterns: (i) a pattern associated with the intense magnetic storms, which is characterized by a higher degree of organization, and (ii) a pattern associated with normal periods, which is characterized by a lower degree of organization. Other entropy measures such as Block Entropy, T-Complexity, Approximate Entropy, Sample Entropy and Fuzzy Entropy verify the above mentioned result. Importantly, the wavelet spectral analysis in terms of Hurst exponent, H, also shows the existence of two different patterns: (i) a pattern associated with the intense magnetic storms, which is characterized by a fractional Brownian persistent behavior (ii) a pattern associated with normal periods, which is characterized by a fractional Brownian anti-persistent behavior. Finally, we observe universality in the magnetic storm and earthquake dynamics, on a basis of a modified form of the Gutenberg-Richter law for the Tsallis statistics. This finding suggests a common approach to the interpretation of both phenomena in terms of the same driving physical mechanism. Signatures of discrete scale invariance in Dst time series further supports the aforementioned proposal.

  9. Activity in prelimbic cortex subserves fear memory reconsolidation over time

    PubMed Central

    Stern, Cristina A.J.; Gazarini, Lucas; Vanvossen, Ana C.; Hames, Mayara S.; Bertoglio, Leandro J.

    2014-01-01

    The prelimbic cortex has been implicated in the consolidation of previously learned fear. Herein, we report that temporarily inactivating this medial prefrontal cortex subregion with the GABAA agonist muscimol (4.0 nmol in 0.2 μL per hemisphere) was able to equally disrupt 1-, 7-, and 21-d-old contextual fear memories after their brief retrieval in rats. In all cases, this effect was prevented when memory reactivation was omitted. These results indicate that recent and remote fear memories are susceptible to reconsolidation blockade induced by prelimbic cortex inactivation. It was also demonstrated that the disrupting effect of prelimbic cortex inactivation on fear memory persisted over 11 d, and did not show extinction-related features, such as reinstatement. Infusing the same dose and volume of muscimol bilaterally into the infralimbic cortex after brief retrieval/reactivation of the fear memory did not disrupt it, as seen in prelimbic cortex-inactivated animals. The expression of Zif268/Egr1, the product of an immediate early gene related to memory reconsolidation, was also less pronounced in the infralimbic cortex than in prelimbic cortex following memory retrieval/reactivation. Altogether, the present findings highlight that activity in the prelimbic cortex may reestablish reactivated aversive memories and, therefore, contribute to their maintenance over time. PMID:24344180

  10. Wall of fundamental constants

    SciTech Connect

    Olive, Keith A.; Peloso, Marco; Uzan, Jean-Philippe

    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 the 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.

  11. Predicted Chemical Activation Rate Constants for HO2 + CH2NH: The Dominant Role of a Hydrogen-Bonded Pre-reactive Complex.

    PubMed

    Ali, Mohamad Akbar; Sonk, Jason A; Barker, John R

    2016-09-15

    The reaction of methanimine (CH2NH) with the hydroperoxy (HO2) radical has been investigated by using a combination of ab initio and density functional theory (CCSD(T)/CBSB7//B3LYP+Dispersion/CBSB7) and master equation calculations based on transition state theory (TST). Variational TST was used to compute both canonical (CVTST) and microcanonical (μVTST) rate constants for barrierless reactions. The title reaction starts with the reversible formation of a cyclic prereactive complex (PRC) that is bound by ∼11 kcal/mol and contains hydrogen bonds to both nitrogen and oxygen. The reaction path for the entrance channel was investigated by a series of constrained optimizations, which showed that the reaction is barrierless (i.e., no intrinsic energy barrier along the path). However, the variations in the potential energy, vibrational frequencies, and rotational constants reveal that the two hydrogen bonds are formed sequentially, producing two reaction flux bottlenecks (i.e., two transition states) along the reaction path, which were modeled using W. H. Miller's unified TST approach. The rate constant computed for the formation of the PRC is pressure-dependent and increases at lower temperatures. Under atmospheric conditions, the PRC dissociates rapidly and its lifetime is too short for it to undergo significant bimolecular reaction with other species. A small fraction isomerizes via a cyclic transition state and subsequent reactions lead to products normally expected from hydrogen abstraction reactions. The kinetics of the HO2 + CH2NH reaction system differs substantially from the analogous isoelectronic reaction systems involving C2H4 and CH2O, which have been the subjects of previous experimental and theoretical studies.

  12. Predicted Chemical Activation Rate Constants for HO2 + CH2NH: The Dominant Role of a Hydrogen-Bonded Pre-reactive Complex.

    PubMed

    Ali, Mohamad Akbar; Sonk, Jason A; Barker, John R

    2016-09-15

    The reaction of methanimine (CH2NH) with the hydroperoxy (HO2) radical has been investigated by using a combination of ab initio and density functional theory (CCSD(T)/CBSB7//B3LYP+Dispersion/CBSB7) and master equation calculations based on transition state theory (TST). Variational TST was used to compute both canonical (CVTST) and microcanonical (μVTST) rate constants for barrierless reactions. The title reaction starts with the reversible formation of a cyclic prereactive complex (PRC) that is bound by ∼11 kcal/mol and contains hydrogen bonds to both nitrogen and oxygen. The reaction path for the entrance channel was investigated by a series of constrained optimizations, which showed that the reaction is barrierless (i.e., no intrinsic energy barrier along the path). However, the variations in the potential energy, vibrational frequencies, and rotational constants reveal that the two hydrogen bonds are formed sequentially, producing two reaction flux bottlenecks (i.e., two transition states) along the reaction path, which were modeled using W. H. Miller's unified TST approach. The rate constant computed for the formation of the PRC is pressure-dependent and increases at lower temperatures. Under atmospheric conditions, the PRC dissociates rapidly and its lifetime is too short for it to undergo significant bimolecular reaction with other species. A small fraction isomerizes via a cyclic transition state and subsequent reactions lead to products normally expected from hydrogen abstraction reactions. The kinetics of the HO2 + CH2NH reaction system differs substantially from the analogous isoelectronic reaction systems involving C2H4 and CH2O, which have been the subjects of previous experimental and theoretical studies. PMID:27529639

  13. Varying constants quantum cosmology

    SciTech Connect

    Leszczyńska, Katarzyna; Balcerzak, Adam; Dabrowski, Mariusz P. E-mail: abalcerz@wmf.univ.szczecin.pl

    2015-02-01

    We discuss minisuperspace models within the framework of varying physical constants theories including Λ-term. In particular, we consider the varying speed of light (VSL) theory and varying gravitational constant theory (VG) using the specific ansätze for the variability of constants: c(a) = c{sub 0} a{sup n} and G(a)=G{sub 0} a{sup q}. We find that most of the varying c and G minisuperspace potentials are of the tunneling type which allows to use WKB approximation of quantum mechanics. Using this method we show that the probability of tunneling of the universe ''from nothing'' (a=0) to a Friedmann geometry with the scale factor a{sub t} is large for growing c models and is strongly suppressed for diminishing c models. As for G varying, the probability of tunneling is large for G diminishing, while it is small for G increasing. In general, both varying c and G change the probability of tunneling in comparison to the standard matter content (cosmological term, dust, radiation) universe models.

  14. Time-Resolved Records of Magnetic Activity on the Pallasite Parent Body and Psyche

    NASA Astrophysics Data System (ADS)

    Bryson, J. F. J.; Nichols, C. I. O.; Herrero-Albillos, J.; Kronast, F.; Kasama, T.; Alimadadi, H.; van der Laan, G.; Nimmo, F.; Harrison, R. J.

    2014-12-01

    Although many small bodies apparently generated dynamo fields in the early solar system, the nature and temporal evolution of these fields has remained enigmatic. Time-resolved records of the Earth's planetary field have been essential in understanding the dynamic history of our planet, and equivalent information from asteroids could provide a unique insight into the development of the solar system. Here we present time-resolved records of magnetic activity on the main-group pallasite parent body and (16) Psyche, obtained using newly-developed nanomagnetic imaging techniques. For the pallasite parent body, the inferred field direction remained relatively constant and the intensity was initially stable at ~100 μT before it decreased in two discrete steps down to 0 μT. We interpret this behaviour as due to vigorous dynamo activity driven by compositional convection in the core, ultimately transitioning from a dipolar to multipolar field as the inner core grew from the bottom-up. For Psyche (measured from IVA iron meteorites), the inferred field direction reversed, while the intensity remained stable at >50 μT. Psyche cooled rapidly as an unmantled core, although the resulting thermal convection alone cannot explain these observations. Instead, this behaviour required top-down core solidification, and is attributed either to compositional convection (if the core also solidified from the bottom-up) or convection generated directly by top-down solidification (e.g. Fe-snow). The mechanism governing convection in small body cores is an open question (due partly to uncertainties in the direction of core solidification), and these observations suggest that unconventional (i.e. not thermal) mechanisms acted in the early solar system. These mechanisms are very efficient at generating convection, implying a long-lasting and widespread epoch of dynamo activity among small bodies in the early solar system.

  15. Sleep and sleep homeostasis in constant darkness in the rat.

    PubMed

    Deboer, Tom; de Boer, Tom

    2009-09-01

    According to the two-process model of sleep regulation, a homeostatic Process S increases during waking and decreases during sleep. The time course of Process S can be derived on the basis of changes in vigilance states and changes in electroencephalogram slow-wave activity (SWA, activity below 4 Hz) during non-rapid eye movement (NREM) sleep. In most mouse strains, an optimal fit between S and SWA was achieved with one increasing (active during waking and REM sleep) and one decreasing time constant (active during NREM sleep) for Process S. However, in the rat, systematic deviations in the light and dark periods were observed, which were resolved by introducing different decreasing time constants between the light and dark periods. The present study shows that this difference between the rest (light) and active (dark) phases remains, and may even be larger, after animals are adapted to constant dark conditions for at least a week. In addition, the data show that the build-up rate of SWA at the onset of a NREM sleep episode is slow compared with the increase rate under light-dark conditions, and that this build-up rate changes with the circadian phase. The slow build-up rate introduces a systematic error between the simulation of Process S and SWA in NREM sleep. The circadian modulation of the build-up rate may, together with circadian changes in NREM sleep episode duration, be the source of the necessity of introducing a difference in the decreasing time constant between the rest and active phases.

  16. Food reward without a timing component does not alter the timing of activity under positive energy balance.

    PubMed

    van der Vinne, V; Akkerman, J; Lanting, G D; Riede, S J; Hut, R A

    2015-09-24

    Circadian clocks drive daily rhythms in physiology and behavior which allow organisms to anticipate predictable daily changes in the environment. In most mammals, circadian rhythms result in nocturnal activity patterns although plasticity of the circadian system allows activity patterns to shift to different times of day. Such plasticity is seen when food access is restricted to a few hours during the resting (light) phase resulting in food anticipatory activity (FAA) in the hours preceding food availability. The mechanisms underlying FAA are unknown but data suggest the involvement of the reward system and homeostatic regulation of metabolism. We previously demonstrated the isolated effect of metabolism by inducing diurnality in response to energetic challenges. Here the importance of reward timing in inducing daytime activity is assessed. The daily activity distribution of mice earning palatable chocolate at their preferred time by working in a running wheel was compared with that of mice receiving a timed palatable meal at noon. Mice working for chocolate (WFC) without being energetically challenged increased their total daily activity but this did not result in a shift to diurnality. Providing a chocolate meal at noon each day increased daytime activity, identifying food timing as a factor capable of altering the daily distribution of activity and rest. These results show that timing of food reward and energetic challenges are both independently sufficient to induce diurnality in nocturnal mammals. FAA observed following timed food restriction is likely the result of an additive effect of distinct regulatory pathways activated by energetic challenges and food reward.

  17. Food reward without a timing component does not alter the timing of activity under positive energy balance.

    PubMed

    van der Vinne, V; Akkerman, J; Lanting, G D; Riede, S J; Hut, R A

    2015-09-24

    Circadian clocks drive daily rhythms in physiology and behavior which allow organisms to anticipate predictable daily changes in the environment. In most mammals, circadian rhythms result in nocturnal activity patterns although plasticity of the circadian system allows activity patterns to shift to different times of day. Such plasticity is seen when food access is restricted to a few hours during the resting (light) phase resulting in food anticipatory activity (FAA) in the hours preceding food availability. The mechanisms underlying FAA are unknown but data suggest the involvement of the reward system and homeostatic regulation of metabolism. We previously demonstrated the isolated effect of metabolism by inducing diurnality in response to energetic challenges. Here the importance of reward timing in inducing daytime activity is assessed. The daily activity distribution of mice earning palatable chocolate at their preferred time by working in a running wheel was compared with that of mice receiving a timed palatable meal at noon. Mice working for chocolate (WFC) without being energetically challenged increased their total daily activity but this did not result in a shift to diurnality. Providing a chocolate meal at noon each day increased daytime activity, identifying food timing as a factor capable of altering the daily distribution of activity and rest. These results show that timing of food reward and energetic challenges are both independently sufficient to induce diurnality in nocturnal mammals. FAA observed following timed food restriction is likely the result of an additive effect of distinct regulatory pathways activated by energetic challenges and food reward. PMID:26215921

  18. Total individual ion activity coefficients of calcium and carbonate in seawater at 25°C and 35%. salinity, and implications to the agreement between apparent and thermodynamic constants of calcite and aragonite

    USGS Publications Warehouse

    Plummer, L. Neil; Sundquist, Eric T.

    1982-01-01

    We have calculated the total individual ion activity coefficients of carbonate and calcium,  and , in seawater. Using the ratios of stoichiometric and thermodynamic constants of carbonic acid dissociation and total mean activity coefficient data measured in seawater, we have obtained values which differ significantly from those widely accepted in the literature. In seawater at 25°C and 35%. salinity the (molal) values of  and  are 0.038 ± 0.002 and 0.173 ± 0.010, respectively. These values of  and  are independent of liquid junction errors and internally consistent with the value . By defining  and  on a common scale (), the product  is independent of the assigned value of  and may be determined directly from thermodynamic measurements in seawater. Using the value  and new thermodynamic equilibrium constants for calcite and aragonite, we show that the apparent constants of calcite and aragonite are consistent with the thermodynamic equilibrium constants at 25°C and 35%. salinity. The demonstrated consistency between thermodynamic and apparent constants of calcite and aragonite does not support a hypothesis of stable Mg-calcite coatings on calcite or aragonite surfaces in seawater, and suggests that the calcite critical carbonate ion curve of Broecker and Takahashi (1978,Deep-Sea Research25, 65–95) defines the calcite equilibrium boundary in the oceans, within the uncertainty of the data.

  19. Highly sensitive index of sympathetic activity based on time-frequency spectral analysis of electrodermal activity.

    PubMed

    Posada-Quintero, Hugo F; Florian, John P; Orjuela-Cañón, Álvaro D; Chon, Ki H

    2016-09-01

    Time-domain indices of electrodermal activity (EDA) have been used as a marker of sympathetic tone. However, they often show high variation between subjects and low consistency, which has precluded their general use as a marker of sympathetic tone. To examine whether power spectral density analysis of EDA can provide more consistent results, we recently performed a variety of sympathetic tone-evoking experiments (43). We found significant increase in the spectral power in the frequency range of 0.045 to 0.25 Hz when sympathetic tone-evoking stimuli were induced. The sympathetic tone assessed by the power spectral density of EDA was found to have lower variation and more sensitivity for certain, but not all, stimuli compared with the time-domain analysis of EDA. We surmise that this lack of sensitivity in certain sympathetic tone-inducing conditions with time-invariant spectral analysis of EDA may lie in its inability to characterize time-varying dynamics of the sympathetic tone. To overcome the disadvantages of time-domain and time-invariant power spectral indices of EDA, we developed a highly sensitive index of sympathetic tone, based on time-frequency analysis of EDA signals. Its efficacy was tested using experiments designed to elicit sympathetic dynamics. Twelve subjects underwent four tests known to elicit sympathetic tone arousal: cold pressor, tilt table, stand test, and the Stroop task. We hypothesize that a more sensitive measure of sympathetic control can be developed using time-varying spectral analysis. Variable frequency complex demodulation, a recently developed technique for time-frequency analysis, was used to obtain spectral amplitudes associated with EDA. We found that the time-varying spectral frequency band 0.08-0.24 Hz was most responsive to stimulation. Spectral power for frequencies higher than 0.24 Hz were determined to be not related to the sympathetic dynamics because they comprised less than 5% of the total power. The mean value of time

  20. Highly sensitive index of sympathetic activity based on time-frequency spectral analysis of electrodermal activity.

    PubMed

    Posada-Quintero, Hugo F; Florian, John P; Orjuela-Cañón, Álvaro D; Chon, Ki H

    2016-09-01

    Time-domain indices of electrodermal activity (EDA) have been used as a marker of sympathetic tone. However, they often show high variation between subjects and low consistency, which has precluded their general use as a marker of sympathetic tone. To examine whether power spectral density analysis of EDA can provide more consistent results, we recently performed a variety of sympathetic tone-evoking experiments (43). We found significant increase in the spectral power in the frequency range of 0.045 to 0.25 Hz when sympathetic tone-evoking stimuli were induced. The sympathetic tone assessed by the power spectral density of EDA was found to have lower variation and more sensitivity for certain, but not all, stimuli compared with the time-domain analysis of EDA. We surmise that this lack of sensitivity in certain sympathetic tone-inducing conditions with time-invariant spectral analysis of EDA may lie in its inability to characterize time-varying dynamics of the sympathetic tone. To overcome the disadvantages of time-domain and time-invariant power spectral indices of EDA, we developed a highly sensitive index of sympathetic tone, based on time-frequency analysis of EDA signals. Its efficacy was tested using experiments designed to elicit sympathetic dynamics. Twelve subjects underwent four tests known to elicit sympathetic tone arousal: cold pressor, tilt table, stand test, and the Stroop task. We hypothesize that a more sensitive measure of sympathetic control can be developed using time-varying spectral analysis. Variable frequency complex demodulation, a recently developed technique for time-frequency analysis, was used to obtain spectral amplitudes associated with EDA. We found that the time-varying spectral frequency band 0.08-0.24 Hz was most responsive to stimulation. Spectral power for frequencies higher than 0.24 Hz were determined to be not related to the sympathetic dynamics because they comprised less than 5% of the total power. The mean value of time

  1. 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.

  2. Predicting Child Physical Activity and Screen Time: Parental Support for Physical Activity and General Parenting Styles

    PubMed Central

    Crain, A. Lauren; Senso, Meghan M.; Levy, Rona L.; Sherwood, Nancy E.

    2014-01-01

    Objective: To examine relationships between parenting styles and practices and child moderate-to-vigorous physical activity (MVPA) and screen time. Methods: Participants were children (6.9 ± 1.8 years) with a body mass index in the 70–95th percentile and their parents (421 dyads). Parent-completed questionnaires assessed parental support for child physical activity (PA), parenting styles and child screen time. Children wore accelerometers to assess MVPA. Results: Parenting style did not predict MVPA, but support for PA did (positive association). The association between support and MVPA, moreover, varied as a function of permissive parenting. For parents high in permissiveness, the association was positive (greater support was related to greater MVPA and therefore protective). For parents low in permissiveness, the association was neutral; support did not matter. Authoritarian and permissive parenting styles were both associated with greater screen time. Conclusions: Parenting practices and styles should be considered jointly, offering implications for tailored interventions. PMID:24812256

  3. Asympotics with positive cosmological constant

    NASA Astrophysics Data System (ADS)

    Bonga, Beatrice; Ashtekar, Abhay; Kesavan, Aruna

    2014-03-01

    Since observations to date imply that our universe has a positive cosmological constant, one needs an extension of the theory of isolated systems and gravitational radiation in full general relativity from the asymptotically flat to asymptotically de Sitter space-times. In current definitions, one mimics the boundary conditions used in asymptotically AdS context to conclude that the asymptotic symmetry group is the de Sitter group. However, these conditions severely restricts radiation and in fact rules out non-zero flux of energy, momentum and angular momentum carried by gravitational waves. Therefore, these formulations of asymptotically de Sitter space-times are uninteresting beyond non-radiative spacetimes. The situation is compared and contrasted with conserved charges and fluxes at null infinity in asymptotically flat space-times.

  4. DNA replication origin activation in space and time.

    PubMed

    Fragkos, Michalis; Ganier, Olivier; Coulombe, Philippe; Méchali, Marcel

    2015-06-01

    DNA replication begins with the assembly of pre-replication complexes (pre-RCs) at thousands of DNA replication origins during the G1 phase of the cell cycle. At the G1-S-phase transition, pre-RCs are converted into pre-initiation complexes, in which the replicative helicase is activated, leading to DNA unwinding and initiation of DNA synthesis. However, only a subset of origins are activated during any S phase. Recent insights into the mechanisms underlying this choice reveal how flexibility in origin usage and temporal activation are linked to chromosome structure and organization, cell growth and differentiation, and replication stress.

  5. About variable constants

    NASA Astrophysics Data System (ADS)

    Blichert-Toft, J.; Albarede, F.

    2011-12-01

    When only modern isotope compositions are concerned, the choice of normalization values is inconsequential provided that their values are universally accepted. No harm is done as long as large amounts of standard reference material with known isotopic differences with respect to the reference value ('anchor point') can be maintained under controlled conditions. For over five decades, the scientific community has been referring to an essentially unavailable SMOW for stable O and H isotopes and to a long-gone belemnite sample for carbon. For radiogenic isotopes, the isotope composition of the daughter element, the parent-daughter ratio, and a particular value of the decay constant are all part of the reference. For the Lu-Hf system, for which the physical measurements of the decay constant have been particularly defective, the reference includes the isotope composition of Hf and the Lu/Hf ratio of an unfortunately heterogeneous chondrite mix that has been successively refined by Patchett and Tatsumoto (1981), Blichert-Toft and Albarede (1997, BTA), and Bouvier et al. (2008, BVP). The \\varepsilonHf(T) difference created by using BTA and BVP is nearly within error (+0.45 epsilon units today and -0.36 at 3 Ga) and therefore of little or no consequence. A more serious issue arises when the chondritic reference is taken to represent the Hf isotope evolution of the Bulk Silicate Earth (BSE): the initial isotope composition of the Solar System, as determined by the indistinguishable intercepts of the external eucrite isochron (Blichert-Toft et al., 2002) and the internal angrite SAH99555 isochron (Thrane et al., 2010), differs from the chondrite value of BTA and BVP extrapolated to 4.56 Ga by ~5 epsilon units. This difference and the overestimated value of the 176Lu decay constant derived from the slopes of these isochrons, have been interpreted as reflecting irradiation of the solar nebula by either gamma (Albarede et al., 2006) or cosmic rays (Thrane et al., 2010) during

  6. Active versus Passive Screen Time for Young Children

    ERIC Educational Resources Information Center

    Sweetser, Penelope; Johnson, Daniel; Ozdowska, Anne; Wyeth, Peta

    2012-01-01

    In this paper we report some initial findings from our investigations into the Australian Government's Longitudinal Study of Australian Children dataset. It is revealed that the majority of Australian children are exceeding the government's Screen Time recommendations and that most of their screen time is spent as TV viewing, as opposed to video…

  7. Family Time Activities and Adolescents' Emotional Well-Being

    ERIC Educational Resources Information Center

    Offer, Shira

    2013-01-01

    The literature is divided on the issue of what matters for adolescents' well-being, with one approach focusing on quality and the other on routine family time. Using the experience sampling method, a unique form of time diary, and survey data drawn from the 500 Family Study ("N" = 237 adolescents with 8,122 observations), this study examined the…

  8. Intrinsically Motivated, Free-Time Physical Activity: Considerations for Recess

    ERIC Educational Resources Information Center

    Stellino, Megan Babkes; Sinclair, Christina D.

    2008-01-01

    The current childhood obesity rates raise concern about youths' health and the role that a sedentary lifestyle plays in this growing trend. Focusing on how children choose to spend their free time is one approach that may yield ideas for reducing childhood obesity. Recess is a regularly occurring "free time" period in elementary schools. It is,…

  9. Measurement of the solar constant

    NASA Technical Reports Server (NTRS)

    Crommelynck, D.

    1981-01-01

    The absolute value of the solar constant and the long term variations that exist in the absolute value of the solar constant were measured. The solar constant is the total irradiance of the Sun at a distance of one astronomical unit. An absolute radiometer removed from the effects of the atmosphere with its calibration tested in situ was used to measure the solar constant. The importance of an accurate knowledge of the solar constant is emphasized.

  10. Instrumented Shoes for Real-Time Activity Monitoring Applications.

    PubMed

    Moufawad El Achkar, Christopher; Lenoble-Hoskovec, Constanze; Major, Kristof; Paraschiv-Ionescu, Anisoara; Büla, Christophe; Aminian, Kamiar

    2016-01-01

    Activity monitoring in daily life is gaining momentum as a health assessment tool, especially in older adults and at-risk populations. Several research-based and commercial systems have been proposed with varying performances in classification accuracy. Configurations with many sensors are generally accurate but cumbersome, whereas single sensors tend to have lower accuracies. To this end, we propose an instrumented shoes system capable of accurate activity classification and gait analysis that contains sensors located entirely at the level of the shoes. One challenge in daily activity monitoring is providing punctual and subject-tailored feedback to improve mobility. Therefore, the instrumented shoe system was equipped with a Bluetooth® module to transmit data to a smartphone and perform detailed activity profiling of the monitored subjects. The potential applications of such a system are numerous in mobility and fall risk-assessment as well as in fall prevention. PMID:27332298

  11. Photo-activated ionic gelation of alginate hydrogel: real-time rheological monitoring of the two-step crosslinking mechanism.

    PubMed

    Higham, Alina K; Bonino, Christopher A; Raghavan, Srinivasa R; Khan, Saad A

    2014-07-21

    We examine the gelation of alginate undergoing ionic crosslinking upon ultraviolet (UV) irradiation using in situ dynamic rheology. Hydrogels are formed by combining alginate with calcium carbonate (CaCO3) particles and a photoacid generator (PAG). The PAG is photolyzed upon UV irradiation, resulting in the release of free calcium ions for ionic crosslinking. The viscous and elastic moduli during gelation are monitored as a function of the UV irradiation intensity, exposure time, alginate concentration, and the ratio between alginate and calcium carbonate. Gel time decreases as irradiation intensity increases because a larger concentration of PAG is photolyzed. Interestingly, dark curing, the continuing growth of microstructure in the absence of UV light, is observed. In some instances, the sample transitions from a solution to a gel during the dark curing phase. Additionally, when exposed to constant UV irradiation after the dark curing phase, samples reach the same plateau modulus as samples exposed to constant UV without dark curing, implying that dark curing does not affect the gelation mechanism. We believe the presence of dark curing is the result of the acidic environment persisting within the sample, allowing CaCO3 to dissociate, thereby releasing free Ca(2+) ions capable of binding with the available appropriate ionic blocks of the polymer chains. The growth of microstructure is then detected if the activation barrier has been crossed to release sufficient calcium ions. In this regard, we calculate a value of 30 J that represents the activation energy required to initiate gelation.

  12. Photo-activated ionic gelation of alginate hydrogel: real-time rheological monitoring of the two-step crosslinking mechanism.

    PubMed

    Higham, Alina K; Bonino, Christopher A; Raghavan, Srinivasa R; Khan, Saad A

    2014-07-21

    We examine the gelation of alginate undergoing ionic crosslinking upon ultraviolet (UV) irradiation using in situ dynamic rheology. Hydrogels are formed by combining alginate with calcium carbonate (CaCO3) particles and a photoacid generator (PAG). The PAG is photolyzed upon UV irradiation, resulting in the release of free calcium ions for ionic crosslinking. The viscous and elastic moduli during gelation are monitored as a function of the UV irradiation intensity, exposure time, alginate concentration, and the ratio between alginate and calcium carbonate. Gel time decreases as irradiation intensity increases because a larger concentration of PAG is photolyzed. Interestingly, dark curing, the continuing growth of microstructure in the absence of UV light, is observed. In some instances, the sample transitions from a solution to a gel during the dark curing phase. Additionally, when exposed to constant UV irradiation after the dark curing phase, samples reach the same plateau modulus as samples exposed to constant UV without dark curing, implying that dark curing does not affect the gelation mechanism. We believe the presence of dark curing is the result of the acidic environment persisting within the sample, allowing CaCO3 to dissociate, thereby releasing free Ca(2+) ions capable of binding with the available appropriate ionic blocks of the polymer chains. The growth of microstructure is then detected if the activation barrier has been crossed to release sufficient calcium ions. In this regard, we calculate a value of 30 J that represents the activation energy required to initiate gelation. PMID:24894636

  13. The Hubble constant.

    PubMed

    Tully, R B

    1993-06-01

    Five methods of estimating distances have demonstrated internal reproducibility at the level of 5-20% rms accuracy. The best of these are the cepheid (and RR Lyrae), planetary nebulae, and surface-brightness fluctuation techniques. Luminosity-line width and Dn-sigma methods are less accurate for an individual case but can be applied to large numbers of galaxies. The agreement is excellent between these five procedures. It is determined that Hubble constant H0 = 90 +/- 10 km.s-1.Mpc-1 [1 parsec (pc) = 3.09 x 10(16) m]. It is difficult to reconcile this value with the preferred world model even in the low-density case. The standard model with Omega = 1 may be excluded unless there is something totally misunderstood about the foundation of the distance scale or the ages of stars. PMID:11607391

  14. The Hubble constant.

    PubMed Central

    Tully, R B

    1993-01-01

    Five methods of estimating distances have demonstrated internal reproducibility at the level of 5-20% rms accuracy. The best of these are the cepheid (and RR Lyrae), planetary nebulae, and surface-brightness fluctuation techniques. Luminosity-line width and Dn-sigma methods are less accurate for an individual case but can be applied to large numbers of galaxies. The agreement is excellent between these five procedures. It is determined that Hubble constant H0 = 90 +/- 10 km.s-1.Mpc-1 [1 parsec (pc) = 3.09 x 10(16) m]. It is difficult to reconcile this value with the preferred world model even in the low-density case. The standard model with Omega = 1 may be excluded unless there is something totally misunderstood about the foundation of the distance scale or the ages of stars. PMID:11607391

  15. 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.

  16. Unitaxial constant velocity microactuator

    DOEpatents

    McIntyre, T.J.

    1994-06-07

    A uniaxial drive system or microactuator capable of operating in an ultra-high vacuum environment is disclosed. 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-nanometer 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. 10 figs.

  17. Constant attitude orbit transfer

    NASA Astrophysics Data System (ADS)

    Cress, Peter; Evans, Michael

    A two-impulse orbital transfer technique is described in which the spacecraft attitude remains constant for both burns, eliminating the need for attitude maneuvers between the burns. This can lead to significant savings in vehicle weight, cost and complexity. Analysis is provided for a restricted class of applications of this transfer between circular orbits. For those transfers with a plane change less than 30 deg, the total velocity cost of the maneuver is less than twelve percent greater than that of an optimum plane split Hohmann transfer. While this maneuver does not minimize velocity requirement, it does provide a means of achieving necessary transfer while substantially reducing the cost and complexity of the spacecraft.

  18. 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.

  19. Clinical NECR in 18F-FDG PET scans: optimization of injected activity and variable acquisition time. Relationship with SNR

    NASA Astrophysics Data System (ADS)

    Carlier, T.; Ferrer, L.; Necib, H.; Bodet-Milin, C.; Rousseau, C.; Kraeber-Bodéré, F.

    2014-10-01

    The injected activity and the acquisition time per bed position for 18F-FDG PET scans are usually optimized by using metrics obtained from phantom experiments. However, optimal activity and time duration can significantly vary from a phantom set-up and from patient to patient. An approach using a patient-specific noise equivalent count rate (NECR) modelling has been previously proposed for optimizing clinical scanning protocols. We propose using the clinical NECR on a large population as a function of the body mass index (BMI) for deriving the optimal injected activity and acquisition duration per bed position. The relationship between the NEC and the signal-to-noise ratio (SNR) was assessed both in a phantom and in a clinical setting. 491 consecutive patients were retrospectively evaluated and divided into 4 BMI subgroups. Two criteria were used to optimize the injected activity and the time per bed position was adjusted using the NECR value while keeping the total acquisition time constant. Finally, the relationship between NEC and SNR was investigated using an anthropomorphic phantom and a population of 507 other patients. While the first dose regimen suggested a unique injected activity (665 MBq) regardless of the BMI, the second dose regimen proposed a variable activity and a total acquisition time according to the BMI. The NEC improvement was around 35% as compared with the local current injection rule. Variable time per bed position was derived according to BMI and anatomical region. NEC and number of true events were found to be highly correlated with SNR for the phantom set-up and partially confirmed in the patient study for the BMI subgroup under 28 kg m-2 suggesting that for the scanner, the nonlinear reconstruction algorithm used in this study and BMI < 28 kg m-2, NEC, or the number of true events linearly correlated with SNR2.

  20. Using smartphones to collect time-activity data for long-term personal-level air pollution exposure assessment.

    PubMed

    Glasgow, Mark L; Rudra, Carole B; Yoo, Eun-Hye; Demirbas, Murat; Merriman, Joel; Nayak, Pramod; Crabtree-Ide, Christina; Szpiro, Adam A; Rudra, Atri; Wactawski-Wende, Jean; Mu, Lina

    2016-06-01

    Because of the spatiotemporal variability of people and air pollutants within cities, it is important to account for a person's movements over time when estimating personal air pollution exposure. This study aimed to examine the feasibility of using smartphones to collect personal-level time-activity data. Using Skyhook Wireless's hybrid geolocation module, we developed "Apolux" (Air, Pollution, Exposure), an Android(TM) smartphone application designed to track participants' location in 5-min intervals for 3 months. From 42 participants, we compared Apolux data with contemporaneous data from two self-reported, 24-h time-activity diaries. About three-fourths of measurements were collected within 5 min of each other (mean=74.14%), and 79% of participants reporting constantly powered-on smartphones (n=38) had a daily average data collection frequency of <10 min. Apolux's degree of temporal resolution varied across manufacturers, mobile networks, and the time of day that data collection occurred. The discrepancy between diary points and corresponding Apolux data was 342.3 m (Euclidian distance) and varied across mobile networks. This study's high compliance and feasibility for data collection demonstrates the potential for integrating smartphone-based time-activity data into long-term and large-scale air pollution exposure studies.

  1. Vicinal coupling constants and protein dynamics.

    PubMed

    Hoch, J C; Dobson, C M; Karplus, M

    1985-07-16

    The effects of motional averaging on the analysis of vicinal spin-spin coupling constants derived from proton NMR studies of proteins have been examined. Trajectories obtained from molecular dynamics simulations of bovine pancreatic trypsin inhibitor and of hen egg white lysozyme were used in conjunction with an expression for the dependence of the coupling constant on the intervening dihedral angle to calculate the time-dependent behavior of the coupling constants. Despite large fluctuations, the time-average values of the coupling constants are not far from those computed for the average structure in the cases where fluctuations occur about a single potential well. The calculated differences show a high correlation with the variation in the magnitude of the fluctuations of individual dihedral angles. For the cases where fluctuations involve multiple sites, large differences are found between the time-average values and the average structure values for the coupling constants. Comparison of the simulation results with the experimental trends suggests that side chains with more than one position are more common in proteins than is inferred from X-ray results. It is concluded that for the main chain, motional effects do not introduce significant errors where vicinal coupling constants are used in structure determinations; however, for side chains, the motional average can alter deductions about the structure. Accurately measured coupling constants are shown to provide information concerning the magnitude of dihedral angle fluctuations.

  2. Time well spent? Assessing nursing-supply chain activities.

    PubMed

    Ferenc, Jeff

    2010-02-01

    The amount of time nurses spend providing direct patient care seems to be continually eroding. So it's little wonder a survey conducted last year of critical care, OR nurses and nurse executives found that half of the 1600 respondents feel they spend too much time on supply chain duties. Most also said their supply chain duties impact patient safe ty and their ability to provide bedside care. Experts interviewed for this report believe it's time for supply chain leaders and nurses to develop a closer working partnership. Included are their recommendations to improve performance.

  3. Time Regained: When People Stop a Physical Activity Program, How Does Their Time Use Change? A Randomised Controlled Trial

    PubMed Central

    Gomersall, Sjaan; Maher, Carol; English, Coralie; Rowlands, Alex; Olds, Tim

    2015-01-01

    The aim of this study was to investigate how previously inactive adults who had participated in a structured, partly supervised 6-week exercise program restructured their time budgets when the program ended. Using a randomised controlled trial design, 129 previously inactive adults were recruited and randomly allocated to one of three groups: a Moderate or Extensive six-week physical activity intervention (150 and 300 additional minutes of exercise per week, respectively) or a Control group. Additional physical activity was accumulated through both group and individual exercise sessions with a wide range of activities. Use of time and time spent in energy expenditure zones was measured using a computerised 24-h self-report recall instrument, the Multimedia Activity Recall for Children and Adults, and accelerometry at baseline, mid- and end-program and at 3- and 6-months follow up. At final follow up, all significant changes in time use domains had returned to within 20 minutes of baseline levels (Physical Activity 1-2 min/d, Active Transport 3-9 min/d, Self-Care 0-2 min/d, Television/Videogames 13-18 min/d in the Moderate and Extensive group, relative to Controls, respectively, p>0.05). Similarly, all significant changes in time spent in the moderate energy expenditure zone had returned to within 1-3 min/d baseline levels (p>0.05), however time spent in vigorous physical activity according to accelerometry estimates remained elevated, although the changes were small in magnitude (1 min/d in the Moderate and Extensive groups, relative to Controls, p=0.01). The results of this study demonstrate strong recidivist patterns in physical activity, but also in other aspects of time use. In designing and determining the effectiveness of exercise interventions, future studies would benefit from considering the whole profile of time use, rather than focusing on individual activities. Trial Registration Australian New Zealand Clinical Trials Registry ACTRN12610000248066 PMID

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

    SciTech Connect

    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 faster than using the constant time step scheme.

  5. Time-resolved Spectroscopy of Active Binary Stars

    NASA Astrophysics Data System (ADS)

    Brown, Alexander

    EUVE has provided the first stellar coronal spectra showing individual emission lines, thereby allowing coronal modelling at a level of sophistication previously unattainable. Long EUVE observations have shown the prevalence of large-scale flaring in the coronae of active binary stars. We propose to obtain EUVE DSS spectra and photometry for 8 active binaries, four of which have never been observed by EUVE (EI Eri, AR Psc, V478 Lyr, BY Dra) and four EUV-bright systems that merit reobservation (Sigma CrB, Sigma Gem, Xi UMa, Lambda And). We shall use these observations to derive high quality quiescent coronal spectra for modelling, and to obtain new flare data. We shall try to coordinate these observations with ground-based radio observations and other spacecraft, if the scheduling allows. The proposed observations will significantly increase the available EUVE spectroscopy of active binaries.

  6. 21 CFR 864.7140 - Activated whole blood clotting time tests.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Activated whole blood clotting time tests. 864....7140 Activated whole blood clotting time tests. (a) Identification. An activated whole blood clotting... pulmonary embolism by measuring the coagulation time of whole blood. (b) Classification. Class...

  7. 21 CFR 864.7140 - Activated whole blood clotting time tests.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Activated whole blood clotting time tests. 864....7140 Activated whole blood clotting time tests. (a) Identification. An activated whole blood clotting... pulmonary embolism by measuring the coagulation time of whole blood. (b) Classification. Class...

  8. 21 CFR 864.7140 - Activated whole blood clotting time tests.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Activated whole blood clotting time tests. 864....7140 Activated whole blood clotting time tests. (a) Identification. An activated whole blood clotting... pulmonary embolism by measuring the coagulation time of whole blood. (b) Classification. Class...

  9. 21 CFR 864.7140 - Activated whole blood clotting time tests.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Activated whole blood clotting time tests. 864....7140 Activated whole blood clotting time tests. (a) Identification. An activated whole blood clotting... pulmonary embolism by measuring the coagulation time of whole blood. (b) Classification. Class...

  10. 21 CFR 864.7140 - Activated whole blood clotting time tests.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Activated whole blood clotting time tests. 864....7140 Activated whole blood clotting time tests. (a) Identification. An activated whole blood clotting... pulmonary embolism by measuring the coagulation time of whole blood. (b) Classification. Class...

  11. Low Discretionary Time as a Barrier to Physical Activity and Intervention Uptake

    ERIC Educational Resources Information Center

    Wolin, Kathleen Y.; Bennett, Gary G.; McNeill, Lorna H.; Sorensen, Glorian; Emmons, Karen M.

    2008-01-01

    Objective: To determine whether self-reported discretionary time was associated with physical activity and uptake of a physical activity promotion intervention in a multi-ethnic urban sample. Methods: We examined the association of self-reported discretionary time with hours/week of leisure-time physical activity at baseline and physical activity…

  12. Circle Time: An Exploratory Study of Activities and Challenging Behavior in Head Start Classrooms

    ERIC Educational Resources Information Center

    Zaghlawan, Hasan Y.; Ostrosky, Michaelene M.

    2011-01-01

    The purpose of this descriptive study was to examine circle time activities in eight Head Start classrooms. A total of 7 h of observations occurred in eight classrooms. Songs and academic activities were the most frequently occurring activities. Challenging behavior during circle time also was examined. The three activities with the highest…

  13. Inhibition of potato polyphenol oxidase by anions and activity in various carboxylate buffers (pH 4.8) at constant ionic strength.

    PubMed

    Malkin, B D; Thickman, K R; Markworth, C J; Wilcox, D E; Kull, F J

    2001-01-01

    The activity of potato polyphenol oxidase (tyrosinase) toward DL-3,4-dihydroxyphenylalanine (K(M) 5.39 mM) was studied using a variety of carboxylate buffers at a common pH and ionic strength. Enzyme activity, greatest in citrate and least in oxalate, correlated with increasing carboxyl concentration and molecular mass. The lower activity in oxalate was attributed to more effective chelation of a copper(II) form of the enzyme by the oxalate dianion. Sodium halide salts inhibited the enzyme. Although there was little difference in inhibition between sodium and potassium salts, the degree and type of inhibition was anion dependent; K(is), values for NaCl and KCl, (competitive inhibitors) were 1.82 and 1.62 mM, whereas Na(2) SO(4) and K(2) SO(4) (mixed inhibitors) had K(is) and K(ii) values in the 250 to 450 mM range. PMID:11342282

  14. A solar cycle timing predictor - The latitude of active regions

    NASA Technical Reports Server (NTRS)

    Schatten, Kenneth H.

    1990-01-01

    A 'Spoerer butterfly' method is used to examine solar cycle 22. It is shown from the latitude of active regions that the cycle can now be expected to peak near November 1989 + or - 8 months, basically near the latter half of 1989.

  15. Time for Action: Advocacy for Physical Activity in Later Life

    ERIC Educational Resources Information Center

    Grant, Bevan

    2010-01-01

    By 2050, the over 65 year's age group will account for approximately one quarter of the population. This will have many unprecedented social and economic consequences of which one is the cost associated with health. A preventive health related behaviour attracting considerable attention is physical activity, something that becomes less popular…

  16. 2D Time-lapse Seismic Tomography Using An Active Time Constraint (ATC) Approach

    EPA Science Inventory

    We propose a 2D seismic time-lapse inversion approach to image the evolution of seismic velocities over time and space. The forward modeling is based on solving the eikonal equation using a second-order fast marching method. The wave-paths are represented by Fresnel volumes rathe...

  17. College Textbook Reading Assignments and Class Time Activity

    ERIC Educational Resources Information Center

    Aagaard, Lola; Conner, Timothy W., II.; Skidmore, Ronald L.

    2014-01-01

    A convenient cluster sample of 105 undergraduate students at a regional university in the midsouth completed a survey regarding their use of college textbooks, what strategies might increase the likelihood of their reading textbook assignments, and their preference for how class time was used. Descriptive analysis was conducted on the results and…

  18. Real-Time GNSS Positioning Along Canada's Active Coastal Margin

    NASA Astrophysics Data System (ADS)

    Henton, J. A.; Dragert, H.; Lu, Y.

    2014-12-01

    High-rate, low-latency Global Navigation Satellite System (GNSS) data are being refined for real-time applications to monitor and report motions related to large earthquakes in coastal British Columbia. Given the tectonic setting of Canada's west coast, specific goals for real-time regional geodetic monitoring are: (1) the collection of GNSS data with adequate station density to identify the deformation field for regional earthquakes with M>7.3; (2) the robust, continuous real-time analyses of GNSS data with a precision of 1-2 cm and a latency of less than 10s; and (3) the display of results with attending automated alarms and estimations of earthquake parameters. Megathrust earthquakes (M>8) are the primary targets for immediate identification, since the tsunamis they generate will strike the coast within 15 to 20 min. However, large (6.0time precise point positioning streams for regional sites received from the Canadian Geodetic Survey (CGS), the Jet Propulsion Laboratory (JPL), and the Plate Boundary Observatory (PBO). The comparison of these various real-time solutions allows a realistic evaluation of day-to-day software performance especially when faced with adverse conditions such as data gaps or poor satellite geometry. Forward models for scenario earthquakes in this region are used to "fingerprint" the coseismic displacements expected from various offshore events which allows an evaluation of the effectiveness of the current regional coverage. The present distribution and density of real-time sites is largely sufficient for aiding the timely estimation of size, location

  19. Adolescents' Time Use: Effects on Substance Use, Delinquency and Sexual Activity

    ERIC Educational Resources Information Center

    Barnes, Grace M.; Hoffman, Joseph H.; Welte, John W.; Farrell, Michael P.; Dintcheff, Barbara A.

    2007-01-01

    Using an integration of social control theory and the routine activity perspective, adolescent time use was examined for effects on problem behaviors. We examined a wide variety of time use categories, including homework, extracurricular activities, sports time, alone time, paid work, housework, television watching, as well as indices of family…

  20. Physical activity and type 1 diabetes: time for a rewire?

    PubMed

    Colberg, Sheri R; Laan, Remmert; Dassau, Eyal; Kerr, David

    2015-05-01

    While being physically active bestows many health benefits on individuals with type 1 diabetes, their overall blood glucose control is not enhanced without an effective balance of insulin dosing and food intake to maintain euglycemia before, during, and after exercise of all types. At present, a number of technological advances are already available to insulin users who desire to be physically active with optimal blood glucose control, although a number of limitations to those devices remain. In addition to continued improvements to existing technologies and introduction of new ones, finding ways to integrate all of the available data to optimize blood glucose control and performance during and following exercise will likely involve development of "smart" calculators, enhanced closed-loop systems that are able to use additional inputs and learn, and social aspects that allow devices to meet the needs of the users. PMID:25568144

  1. Molecular Mechanisms and Timing of Cortical Immune Activation in Schizophrenia

    PubMed Central

    Volk, David W.; Chitrapu, Anjani; Edelson, Jessica R.; Roman, Kaitlyn M.; Moroco, Annie E.; Lewis, David A.

    2016-01-01

    Objective Immune-related abnormalities are commonly reported in schizophrenia, including higher mRNA levels for the viral restriction factor interferon-induced transmembrane protein (IFITM) in the prefrontal cortex. The authors sought to clarify whether higher IFITM mRNA levels and other immune-related disturbances in the prefrontal cortex are the consequence of an ongoing molecular cascade contributing to immune activation or the reflection of a long-lasting maladaptive response to an in utero immune-related insult. Method Quantitative polymerase chain reaction was employed to measure mRNA levels for immune-related cytokines and transcriptional regulators, including those reported to regulate IFITM expression, in the prefrontal cortex from 62 schizophrenia and 62 healthy subjects and from adult mice exposed prenatally to maternal immune activation or in adulthood to the immune stimulant poly(I:C). Results Schizophrenia subjects had markedly higher mRNA levels for interleukin 6 (IL-6) (+379%) and interferon-β (+29%), which induce IFITM expression; lower mRNA levels for Schnurri-2 (−10%), a transcriptional inhibitor that lowers IFITM expression; and higher mRNA levels for nuclear factor-κB (+86%), a critical transcription factor that mediates cytokine regulation of immune-related gene expression. In adult mice that received daily poly(I:C) injections, but not in offspring with prenatal exposure to maternal immune activation, frontal cortex mRNA levels were also markedly elevated for IFITM (+304%), multiple cytokines including IL-6 (+493%), and nuclear factor-κB (+151%). Conclusions These data suggest that higher prefrontal cortex IFITM mRNA levels in schizophrenia may be attributable to adult, but not prenatal, activation of multiple immune markers and encourage further investigation into the potential role of these and other immune markers as therapeutic targets in schizophrenia. PMID:26133963

  2. Effects of forward and backward transitions in light intensities in tau-illuminance curves of the rat motor activity rhythm under constant dim light.

    PubMed

    Cambras, Trinitat; Díez-Noguera, Antoni

    2012-07-01

    Circadian rhythms are strongly influenced by light intensity, the effects of which may persist beyond the duration of light exposure (aftereffects). Here, the authors constructed period-illuminance curves for the motor activity circadian rhythm of male and female rats by recording the effects of a series of small upward and downward steps in light intensity (illuminance ranging between .01 lux of dim red light and 1 lux of white light) on their activity. In all cases, stepwise changes were made in five logarithmic steps (irradiance: dim red light: .692 µW/cm(2) and white light: .006, .016, .044, .12, and .315 µW/cm(2), corresponding, respectively, to .02, .05, .14, .13, and 1 lux measured at cage level), with changes in intensity every 2 wks. One group of rats (DLD) started in dim red light, moved up to 1 lux white light, and then back down to the original light intensity. Another group (LDL) started at 1 lux, moved down to .01 lux, and then back up to the original intensity. Motor activity data were recorded throughout the experiment and tau values, the percentage of variance explained by the rhythm, and the mean motor activity for each stage and group were calculated. The results show differences in the dynamics of tau values between the DLD and LDL groups and between males and females. In the LDL group, the tau values of both males and females were dependent on light intensity, and were similar for the forward and backward transitions. In other words, no aftereffects were found, and no differences were detected between males and females. In the DLD group, however, differences were found between males and females. Males had a tau value of 24 h 20 min under dim red light, 25 h 40 min under 1 lux, and 24 h 50 min on return to dim red light. It is noticeable that the tau values of the backward branch of the illuminance curve contradicted classical predictions, since at .38 and .14 lux the tau values were shorter than those found under the same intensities after

  3. Locating and Activating Molecular 'Time Bombs': Induction of Mycolata Prophages.

    PubMed

    Dyson, Zoe A; Brown, Teagan L; Farrar, Ben; Doyle, Stephen R; Tucci, Joseph; Seviour, Robert J; Petrovski, Steve

    2016-01-01

    Little is known about the prevalence, functionality and ecological roles of temperate phages for members of the mycolic acid producing bacteria, the Mycolata. While many lytic phages infective for these organisms have been isolated, and assessed for their suitability for use as biological control agents of activated sludge foaming, no studies have investigated how temperate phages might be induced for this purpose. Bioinformatic analysis using the PHAge Search Tool (PHAST) on Mycolata whole genome sequence data in GenBank for members of the genera Gordonia, Mycobacterium, Nocardia, Rhodococcus, and Tsukamurella revealed 83% contained putative prophage DNA sequences. Subsequent prophage inductions using mitomycin C were conducted on 17 Mycolata strains. This led to the isolation and genome characterization of three novel Caudovirales temperate phages, namely GAL1, GMA1, and TPA4, induced from Gordonia alkanivorans, Gordonia malaquae, and Tsukamurella paurometabola, respectively. All possessed highly distinctive dsDNA genome sequences.

  4. Locating and Activating Molecular 'Time Bombs': Induction of Mycolata Prophages.

    PubMed

    Dyson, Zoe A; Brown, Teagan L; Farrar, Ben; Doyle, Stephen R; Tucci, Joseph; Seviour, Robert J; Petrovski, Steve

    2016-01-01

    Little is known about the prevalence, functionality and ecological roles of temperate phages for members of the mycolic acid producing bacteria, the Mycolata. While many lytic phages infective for these organisms have been isolated, and assessed for their suitability for use as biological control agents of activated sludge foaming, no studies have investigated how temperate phages might be induced for this purpose. Bioinformatic analysis using the PHAge Search Tool (PHAST) on Mycolata whole genome sequence data in GenBank for members of the genera Gordonia, Mycobacterium, Nocardia, Rhodococcus, and Tsukamurella revealed 83% contained putative prophage DNA sequences. Subsequent prophage inductions using mitomycin C were conducted on 17 Mycolata strains. This led to the isolation and genome characterization of three novel Caudovirales temperate phages, namely GAL1, GMA1, and TPA4, induced from Gordonia alkanivorans, Gordonia malaquae, and Tsukamurella paurometabola, respectively. All possessed highly distinctive dsDNA genome sequences. PMID:27487243

  5. Understanding Time-driven Activity-based Costing.

    PubMed

    Sharan, Alok D; Schroeder, Gregory D; West, Michael E; Vaccaro, Alexander R

    2016-03-01

    Transitioning to a value-based health care system will require providers to increasingly scrutinize their outcomes and costs. Although there has been a great deal of effort to understand outcomes, cost accounting in health care has been a greater challenge. Currently the cost accounting methods used by hospitals and providers are based off a fee-for-service system. As resources become increasingly scarce and the health care system attempts to understand which services provide the greatest value, it will be critically important to understand the true costs of delivering a service. An understanding of the true costs of a particular service will help providers make smarter decisions on how to allocate and utilize resources as well as determine which activities are nonvalue added. Achieving value will require providers to have a greater focus on accurate outcome data as well as better methods of cost accounting. PMID:26889988

  6. Understanding Time-driven Activity-based Costing.

    PubMed

    Sharan, Alok D; Schroeder, Gregory D; West, Michael E; Vaccaro, Alexander R

    2016-03-01

    Transitioning to a value-based health care system will require providers to increasingly scrutinize their outcomes and costs. Although there has been a great deal of effort to understand outcomes, cost accounting in health care has been a greater challenge. Currently the cost accounting methods used by hospitals and providers are based off a fee-for-service system. As resources become increasingly scarce and the health care system attempts to understand which services provide the greatest value, it will be critically important to understand the true costs of delivering a service. An understanding of the true costs of a particular service will help providers make smarter decisions on how to allocate and utilize resources as well as determine which activities are nonvalue added. Achieving value will require providers to have a greater focus on accurate outcome data as well as better methods of cost accounting.

  7. Effect of a school-based active play intervention on sedentary time and physical activity in preschool children.

    PubMed

    O'Dwyer, M V; Fairclough, S J; Ridgers, N D; Knowles, Z R; Foweather, L; Stratton, G

    2013-12-01

    Early childhood is a critical time for promoting physical activity. Few studies have investigated the effect of interventions in this population. The aim of this study was to investigate the effect of a school-based active play intervention on preschool children's sedentary time and physical activity. Preschool children were recruited from randomly selected preschools. Schools were randomly assigned to an intervention or comparison group. One teacher per intervention school received training from active play professionals in the delivery of a 6-week active play programme. Comparison schools continued their usual practice. Children wore a uni-axial accelerometer for 7 days at baseline, immediately after and at 6-month post-intervention. No significant intervention effects were observed for sedentary time or physical activity. However, sex and hours spent at school were significant predictors of physical activity. Children who spent fewer hours (half-day children) at school were significantly more active than their full-day counterparts. Physical activity during the intervention classes was high even though neither daily physical activity nor sedentary time changed. Notably children who spent more time at preschool were less active suggesting that preschool was not as conducive to physical activity engagement as other environments.

  8. Physical Activity, Screen Time, and Sitting among US Adolescents

    PubMed Central

    Carson, Valerie; Staiano, Amanda E.; Katzmarzyk, Peter T.

    2015-01-01

    Purpose To describe daily levels of sitting, moderate- to vigorous-intensity physical activity (MVPA), television viewing, and computer use in a representative sample of US adolescents and to make comparisons between sex, race/ethnicity, weight status, and age groups. Methods Results are based on 3556 adolescents aged 12-19 years from the 2007-2012 National Health and Nutrition Examination Survey. Participants self-reported demographic variables and their sitting, MVPA, and television viewing (2011-2012 only) and computer use (2011-2012 only) levels. Height and weight were measured to calculate body mass index. Descriptive data were calculated and ANOVA, chi-square, and logistic regression analyses were conducted to examine demographic differences. Results On average, 7.5 hours/day were spent sitting, with females sitting more than males across the majority of demographic groups. Furthermore, obese males sat more than non-overweight males. For MVPA, the overall sample participated in a median 34 minutes/day, with females participating in less MVPA than males across all demographic groups. Additionally, non-overweight males participated in more MVPA than obese males, and non-Hispanic white females participated in more MVPA than females in all other race/ethnicity groups. For television viewing and computer use, 38% and 22% of the sample engaged in more than 2 hours/day, respectively, and several race/ethnicity differences were observed. Conclusions This study provides the first US population estimates on the levels of sitting and updates population estimates of MVPA, television viewing and computer use in US adolescents. Continued efforts are needed to promote healthy active lifestyles in American adolescents. PMID:25050541

  9. A problem with estimating the pseudo- activation energy of kerogen thermal maturation from Connan's time-temperature relation in oil genesis.

    USGS Publications Warehouse

    Barker, C.E.

    1984-01-01

    Connan's time-temperature relation in oil genesis as derived from first-order reaction kinetics is algebraically correct, but its application to natural petroleum generation is invalidated by the assumption that the ratio of initial kerogen concentration to degraded kerogen concentration is constant from deposition to the initiation of intense oil generation. The ratio can only remain constant if no reaction is occurring and, therefore, Connan's data on 'reaction time' in petroleum generation (assumed to be the age of the sediment) only measures the time elapsed since the system formed. Thus, the widely cited pseudo-activation energy of 11-14 kcal/mole computed from Connan's equation for the start of oil generation from kerogen is meaningless.-Author

  10. Real-Time Active Cosmic Neutron Background Reduction Methods

    SciTech Connect

    Mukhopadhyay, Sanjoy; Maurer, Richard; Wolff, Ronald; Mitchell, Stephen; Guss, Paul

    2013-09-01

    Neutron counting using large arrays of pressurized 3He proportional counters from an aerial system or in a maritime environment suffers from the background counts from the primary cosmic neutrons and secondary neutrons caused by cosmic ray-induced mechanisms like spallation and charge-exchange reaction. This paper reports the work performed at the Remote Sensing Laboratory–Andrews (RSL-A) and results obtained when using two different methods to reduce the cosmic neutron background in real time. Both methods used shielding materials with a high concentration (up to 30% by weight) of neutron-absorbing materials, such as natural boron, to remove the low-energy neutron flux from the cosmic background as the first step of the background reduction process. Our first method was to design, prototype, and test an up-looking plastic scintillator (BC-400, manufactured by Saint Gobain Corporation) to tag the cosmic neutrons and then create a logic pulse of a fixed time duration (~120 μs) to block the data taken by the neutron counter (pressurized 3He tubes running in a proportional counter mode). The second method examined the time correlation between the arrival of two successive neutron signals to the counting array and calculated the excess of variance (Feynman variance Y2F)1 in the neutron count distribution from Poisson distribution. The dilution of this variance from cosmic background values ideally would signal the presence of man-made neutrons.2 The first method has been technically successful in tagging the neutrons in the cosmic-ray flux and preventing them from being counted in the 3He tube array by electronic veto—field measurement work shows the efficiency of the electronic veto counter to be about 87%. The second method has successfully derived an empirical relationship between the percentile non-cosmic component in a neutron flux and the Y2F of the measured neutron count distribution. By using shielding materials alone, approximately 55% of the neutron flux

  11. Real-time active cosmic neutron background reduction methods

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Sanjoy; Maurer, Richard; Wolff, Ronald; Mitchell, Stephen; Guss, Paul

    2013-09-01

    Neutron counting using large arrays of pressurized 3He proportional counters from an aerial system or in a maritime environment suffers from the background counts from the primary cosmic neutrons and secondary neutrons caused by cosmic ray‒induced mechanisms like spallation and charge-exchange reaction. This paper reports the work performed at the Remote Sensing Laboratory-Andrews (RSL-A) and results obtained when using two different methods to reduce the cosmic neutron background in real time. Both methods used shielding materials with a high concentration (up to 30% by weight) of neutron-absorbing materials, such as natural boron, to remove the lowenergy neutron flux from the cosmic background as the first step of the background reduction process. Our first method was to design, prototype, and test an up-looking plastic scintillator (BC-400, manufactured by Saint Gobain Corporation) to tag the cosmic neutrons and then create a logic pulse of a fixed time duration (~120 μs) to block the data taken by the neutron counter (pressurized 3He tubes running in a proportional counter mode). The second method examined the time correlation between the arrival of two successive neutron signals to the counting array and calculated the excess of variance (Feynman variance Y2F)1 in the neutron count distribution from Poisson distribution. The dilution of this variance from cosmic background values ideally would signal the presence of manmade neutrons.2 The first method has been technically successful in tagging the neutrons in the cosmic-ray flux and preventing them from being counted in the 3He tube array by electronic veto—field measurement work shows the efficiency of the electronic veto counter to be about 87%. The second method has successfully derived an empirical relationship between the percentile non-cosmic component in a neutron flux and the Y2F of the measured neutron count distribution. By using shielding materials alone, approximately 55% of the neutron flux

  12. Global Night-Time Lights for Observing Human Activity

    NASA Technical Reports Server (NTRS)

    Hipskind, Stephen R.; Elvidge, Chris; Gurney, K.; Imhoff, Mark; Bounoua, Lahouari; Sheffner, Edwin; Nemani, Ramakrishna R.; Pettit, Donald R.; Fischer, Marc

    2011-01-01

    We present a concept for a small satellite mission to make systematic, global observations of night-time lights with spatial resolution suitable for discerning the extent, type and density of human settlements. The observations will also allow better understanding of fine scale fossil fuel CO2 emission distribution. The NASA Earth Science Decadal Survey recommends more focus on direct observations of human influence on the Earth system. The most dramatic and compelling observations of human presence on the Earth are the night light observations taken by the Defence Meteorological System Program (DMSP) Operational Linescan System (OLS). Beyond delineating the footprint of human presence, night light data, when assembled and evaluated with complementary data sets, can determine the fine scale spatial distribution of global fossil fuel CO2 emissions. Understanding fossil fuel carbon emissions is critical to understanding the entire carbon cycle, and especially the carbon exchange between terrestrial and oceanic systems.

  13. Parallel effects of memory set activation and search on timing and working memory capacity

    PubMed Central

    Schweickert, Richard; Fortin, Claudette; Xi, Zhuangzhuang; Viau-Quesnel, Charles

    2014-01-01

    Accurately estimating a time interval is required in everyday activities such as driving or cooking. Estimating time is relatively easy, provided a person attends to it. But a brief shift of attention to another task usually interferes with timing. Most processes carried out concurrently with timing interfere with it. Curiously, some do not. Literature on a few processes suggests a general proposition, the Timing and Complex-Span Hypothesis: A process interferes with concurrent timing if and only if process performance is related to complex span. Complex-span is the number of items correctly recalled in order, when each item presented for study is followed by a brief activity. Literature on task switching, visual search, memory search, word generation and mental time travel supports the hypothesis. Previous work found that another process, activation of a memory set in long term memory, is not related to complex-span. If the Timing and Complex-Span Hypothesis is true, activation should not interfere with concurrent timing in dual-task conditions. We tested such activation in single-task memory search task conditions and in dual-task conditions where memory search was executed with concurrent timing. In Experiment 1, activating a memory set increased reaction time, with no significant effect on time production. In Experiment 2, set size and memory set activation were manipulated. Activation and set size had a puzzling interaction for time productions, perhaps due to difficult conditions, leading us to use a related but easier task in Experiment 3. In Experiment 3 increasing set size lengthened time production, but memory activation had no significant effect. Results here and in previous literature on the whole support the Timing and Complex-Span Hypotheses. Results also support a sequential organization of activation and search of memory. This organization predicts activation and set size have additive effects on reaction time and multiplicative effects on percent

  14. A hundred years of activated sludge: time for a rethink

    PubMed Central

    Sheik, Abdul R.; Muller, Emilie E. L.; Wilmes, Paul

    2014-01-01

    Biological wastewater treatment plants (BWWTPs) based on the activated sludge (AS) process have dramatically improved worldwide water sanitation despite increased urbanization and industrialization. However, current AS-based operations are considered economically and environmentally unsustainable. In this Perspective, we discuss our current understanding of microbial populations and their metabolic transformations in AS-based BWWTPs in view of developing more sustainable processes in the future. In particular, much has been learned over the course of the past 25 years about specialized microorganisms, which could be more comprehensively leveraged to recover energy and/or nutrients from wastewater streams. To achieve this, we propose a bottom-up design approach, focused around the concept of a “wastewater biorefinery column”, which would rely on the engineering of distinct ecological niches into a BWWTP in order to guarantee the targeted enrichment of specific organismal groups which in turn will allow the harvest of high-value resources from wastewater. This concept could be seen as a possible grand challenge to microbial ecologists and engineers alike at the centenary of the discovery of the AS process. PMID:24624120

  15. "Active Living" Related to the Rural-Urban Continuum: A Time-Use Perspective

    ERIC Educational Resources Information Center

    Millward, Hugh; Spinney, Jamie

    2011-01-01

    Purpose: This paper assesses the degree to which "active living" varies along the rural-urban continuum, within the county-sized regional municipality of Halifax, Nova Scotia. Methods: Time-diary data from the Halifax Space-Time Activity Research project were used to compute daily participation rates (PRs) and time durations, at various physical…

  16. The Daily Lives of Adolescents with an Autism Spectrum Disorder: Discretionary Time Use and Activity Partners

    ERIC Educational Resources Information Center

    Orsmond, Gael I.; Kuo, Hsin-Yu

    2011-01-01

    This study explores the daily lives, particularly discretionary time, of adolescents with an autism spectrum disorder (ASD). We describe the activities and activity partners of adolescents, the factors associated with their discretionary time use, and the impact of time use on their autism symptoms. Mothers of 103 adolescents with an ASD completed…

  17. Implications for future activity of Grímsvötn volcano, Iceland, from compositional time series of historical tephra

    NASA Astrophysics Data System (ADS)

    Carpentier, Marion; Sigmarsson, Olgeir; Larsen, Gudrun

    2014-05-01

    The nature of future eruptions of active volcanoes is hard to predict. Improved understanding of the past volcanic activity is probably the best way to infer future eruptive scenarios. The most active volcano in Iceland, Grímsvötn, last erupted in 2011 with consequences for habitants living close to the volcano and aviation in the North-Atlantic. In an effort to better understand the magmatic system of the volcano, we have investigated the compositions of 23 selected tephra layers representing the last 8 centuries of volcanic activity at Grímsvötn. The tephra was collected in the ablation area of outlet glaciers from Vatnajökull ice cap. The ice-conserved tephra are less prone to alteration than those exposed in soil sections. Major element analyses are indistinguishable and of quartz-normative tholeiite composition, and Sr and Nd isotope ratios are constant. In contrast, both trace element concentrations (Th range from 0.875 ppm to 1.37 ppm and Ni from 28.5 ppm to 56.6 ppm) in the basalts and Pb isotopes show small but significant variations. The high-precision analyses of Pb isotope ratios allow the identification of tephra samples (3 in total) with more radiogenic ratios than the bulk of the samples. The tephra of constant isotope ratios show linear increase in incompatible element concentrations with time. The rate of increasing concentrations permits exploring possible future scenarios assuming that the magmatic system beneath the volcano follows the established historical evolution. Assuming similar future behaviour of the magma system beneath Grímsvötn volcano, the linear increase in e.g. Th concentration suggests that the volcano is likely to principally produce basalts for the next 500-1000 years. Evolution of water concentration will most likely follow those of incompatible elements with consequent increases in explosiveness of future Grímsvötn eruptions.

  18. Physical Activity, Study Sitting Time, Leisure Sitting Time, and Sleep Time Are Differently Associated With Obesity in Korean Adolescents: A Population-Based Study.

    PubMed

    Kong, Il Gyu; Lee, Hyo-Jeong; Kim, So Young; Sim, Songyong; Choi, Hyo Geun

    2015-11-01

    Low physical activity, long leisure sitting time, and short sleep time are risk factors for obesity, but the association with study sitting time is unknown. The objective of this study was to evaluate the association between these factors and obesity.We analyzed the association between physical activity, study sitting time, leisure sitting time, and sleep time and subject weight (underweight, healthy weight, overweight, and obese), using data from a large population-based survey, the 2013 Korea Youth Risk Behavior Web-based Survey. Data from 53,769 participants were analyzed using multinomial logistic regression analyses with complex sampling. Age, sex, region of residence, economic level, smoking, stress level, physical activity, sitting time for study, sitting time for leisure, and sleep time were adjusted as the confounders.Low physical activity (adjusted odds ratios [AORs] = 1.03, 1.12) and long leisure sitting time (AORs = 1.15, 1.32) were positively associated with overweight and obese. Low physical activity (AOR = 1.33) and long leisure sitting time (AOR = 1.12) were also associated with underweight. Study sitting time was negatively associated with underweight (AOR = 0.86) but was unrelated to overweight (AOR = 0.97, 95% confidence interval [CI] = 0.91-1.03) and obese (AOR = 0.94, 95% CI = 0.84-1.04). Sleep time (<6 hours; ≥6 hours, <7 hours; ≥7 hours, <8 hours) was adversely associated with underweight (AORs = 0.67, 0.79, and 0.88) but positively associated with overweight (AORs = 1.19, 1.17, and 1.08) and obese (AORs = 1.33, 1.36, and 1.30) in a dose-response relationship.In adolescents, increasing physical activity, decreasing leisure sitting time, and obtaining sufficient sleep would be beneficial in maintaining a healthy weight. However, study sitting time was not associated with overweight or obese. PMID:26554807

  19. TOPICAL REVIEW The cosmological constant puzzle

    NASA Astrophysics Data System (ADS)

    Bass, Steven D.

    2011-04-01

    The accelerating expansion of the Universe points to a small positive vacuum energy density and negative vacuum pressure. A strong candidate is the cosmological constant in Einstein's equations of general relativity. Possible contributions are zero-point energies and the condensates associated with spontaneous symmetry breaking. The vacuum energy density extracted from astrophysics is 1056 times smaller than the value expected from quantum fields and standard model particle physics. Is the vacuum energy density time dependent? We give an introduction to the cosmological constant puzzle and ideas how to solve it.

  20. 21 CFR 1250.42 - Water systems; constant temperature bottles.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Water systems; constant temperature bottles. 1250...; constant temperature bottles. (a) The water system, whether of the pressure or gravity type, shall be... at all times as to prevent contamination of the water. (e) Constant temperature bottles and...

  1. 21 CFR 1250.42 - Water systems; constant temperature bottles.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Water systems; constant temperature bottles. 1250...; constant temperature bottles. (a) The water system, whether of the pressure or gravity type, shall be... at all times as to prevent contamination of the water. (e) Constant temperature bottles and...

  2. 21 CFR 1250.42 - Water systems; constant temperature bottles.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Water systems; constant temperature bottles. 1250...; constant temperature bottles. (a) The water system, whether of the pressure or gravity type, shall be... at all times as to prevent contamination of the water. (e) Constant temperature bottles and...

  3. Comparison of the rate constants for energy transfer in the light-harvesting protein, C-phycocyanin, calculated from Foerster`s theory and experimentally measured by time-resolved fluorescence spectroscopy

    SciTech Connect

    Debreczeny, M.P.

    1994-05-01

    We have measured and assigned rate constants for energy transfer between chromophores in the light-harvesting protein C-phycocyanin (PC), in the monomeric and trimeric aggregation states, isolated from Synechococcus sp. PCC 7002. In order to compare the measured rate constants with those predicted by Fdrster`s theory of inductive resonance in the weak coupling limit, we have experimentally resolved several properties of the three chromophore types ({beta}{sub 155} {alpha}{sub 84}, {beta}{sub 84}) found in PC monomers, including absorption and fluorescence spectra, extinction coefficients, fluorescence quantum yields, and fluorescence lifetimes. The cpcB/C155S mutant, whose PC is missing the {beta}{sub 155} chromophore, was, useful in effecting the resolution of the chromophore properties and in assigning the experimentally observed rate constants for energy transfer to specific pathways.

  4. Time-dependent effects of dim light at night on re-entrainment and masking of hamster activity rhythms.

    PubMed

    Frank, David W; Evans, Jennifer A; Gorman, Michael R

    2010-04-01

    Bright light has been established as the most ubiquitous environmental cue that entrains circadian timing systems under natural conditions. Light equivalent in intensity to moonlight (<1 lux), however, also strongly modulates circadian function in a number of entrainment paradigms. For example, compared to completely dark nights, dim nighttime illumination accelerated re-entrainment of hamster activity rhythms to 4-hour phase advances and delays of an otherwise standard laboratory photocycle. The purpose of this study was to determine if a sensitive period existed in the night during which dim illumination had a robust influence on speed of re-entrainment. Male Siberian hamsters were either exposed to dim light throughout the night, for half of the night, or not at all. Compared to dark nights, dim illumination throughout the entire night decreased by 29% the time for the midpoint of the active phase to re-entrain to a 4-hour phase advance and by 26% for a 4-hour delay. Acceleration of advances and delays were also achieved with 5 hours of dim light per night, but effects depended on whether dim light was present in the first half, second half, or first and last quarters of the night. Both during phase shifting and steady-state entrainment, partially lit nights also produced strong positive and negative masking effects, as well as entrainment aftereffects in constant darkness. Thus, even in the presence of a strong zeitgeber, light that might be encountered under a natural nighttime sky potently modulates the circadian timing system of hamsters.

  5. ON THE VARIATIONS OF FUNDAMENTAL CONSTANTS AND ACTIVE GALACTIC NUCLEUS FEEDBACK IN THE QUASI-STELLAR OBJECT HOST GALAXY RXJ0911.4+0551 at z = 2.79

    SciTech Connect

    Weiss, A.; Henkel, C.; Menten, K. M.; Walter, F.; Downes, D.; Cox, P.; Carrili, C. L.

    2012-07-10

    We report on sensitive observations of the CO(J = 7{yields}6) and C I({sup 3}P{sub 2} {yields} {sup 3}P{sub 1}) transitions in the z = 2.79 QSO host galaxy RXJ0911.4+0551 using the IRAM Plateau de Bure interferometer. Our extremely high signal-to-noise spectra combined with the narrow CO line width of this source (FWHM = 120 km s{sup -1}) allows us to estimate sensitive limits on the spacetime variations of the fundamental constants using two emission lines. Our observations show that the C I and CO line shapes are in good agreement with each other but that the C I line profile is of the order of 10% narrower, presumably due to the lower opacity in the latter line. Both lines show faint wings with velocities up to {+-}250 km s{sup -1}, indicative of a molecular outflow. As such, the data provide direct evidence for negative feedback in the molecular gas phase at high redshift. Our observations allow us to determine the observed frequencies of both transitions with so far unmatched accuracy at high redshift. The redshift difference between the CO and C I lines is sensitive to variations of {Delta}F/F with F = {alpha}{sup 2}/{mu} where {alpha} is the fine structure constant and {mu} is the electron-to-proton mass ratio. We find {Delta}F/F (6.9 {+-} 3.7) Multiplication-Sign 10{sup -6} at a look-back time of 11.3 Gyr, which, within the uncertainties, is consistent with no variations of the fundamental constants.

  6. Accelerometer-Measured Physical Activity and Sedentary Time Differ According to Education Level in Young Adults.

    PubMed

    Kantomaa, Marko T; Tikanmäki, Marjaana; Kankaanpää, Anna; Vääräsmäki, Marja; Sipola-Leppänen, Marika; Ekelund, Ulf; Hakonen, Harto; Järvelin, Marjo-Riitta; Kajantie, Eero; Tammelin, Tuija H

    2016-01-01

    This study examined the association of education level with objectively measured physical activity and sedentary time in young adults. Data from the Finnish ESTER study (2009-2011) (n = 538) was used to examine the association between educational attainment and different subcomponents of physical activity and sedentary time measured using hip-worn accelerometers (ActiGraph GT1M) for seven consecutive days. Overall physical activity, moderate-to-vigorous physical activity (MVPA), light-intensity physical activity and sedentary time were calculated separately for weekdays and weekend days. A latent profile analysis was conducted to identify the different profiles of sedentary time and the subcomponents of physical activity. The educational differences in accelerometer-measured physical activity and sedentary time varied according to the subcomponents of physical activity, and between weekdays and weekend days. A high education level was associated with high MVPA during weekdays and weekend days in both sexes, high sedentary time during weekdays in both sexes, and a low amount of light-intensity physical activity during weekdays in males and during weekdays and weekend days in females. The results indicate different challenges related to unhealthy behaviours in young adults with low and high education: low education is associated with a lack of MVPA, whereas high education is associated with a lack of light-intensity physical activity and high sedentary time especially during weekdays. PMID:27403958

  7. Accelerometer-Measured Physical Activity and Sedentary Time Differ According to Education Level in Young Adults

    PubMed Central

    Kantomaa, Marko T.; Tikanmäki, Marjaana; Kankaanpää, Anna; Vääräsmäki, Marja; Sipola-Leppänen, Marika; Ekelund, Ulf; Hakonen, Harto; Järvelin, Marjo-Riitta; Kajantie, Eero; Tammelin, Tuija H.

    2016-01-01

    This study examined the association of education level with objectively measured physical activity and sedentary time in young adults. Data from the Finnish ESTER study (2009–2011) (n = 538) was used to examine the association between educational attainment and different subcomponents of physical activity and sedentary time measured using hip-worn accelerometers (ActiGraph GT1M) for seven consecutive days. Overall physical activity, moderate-to-vigorous physical activity (MVPA), light-intensity physical activity and sedentary time were calculated separately for weekdays and weekend days. A latent profile analysis was conducted to identify the different profiles of sedentary time and the subcomponents of physical activity. The educational differences in accelerometer-measured physical activity and sedentary time varied according to the subcomponents of physical activity, and between weekdays and weekend days. A high education level was associated with high MVPA during weekdays and weekend days in both sexes, high sedentary time during weekdays in both sexes, and a low amount of light-intensity physical activity during weekdays in males and during weekdays and weekend days in females. The results indicate different challenges related to unhealthy behaviours in young adults with low and high education: low education is associated with a lack of MVPA, whereas high education is associated with a lack of light-intensity physical activity and high sedentary time especially during weekdays. PMID:27403958

  8. Time to care? Health of informal older carers and time spent on health related activities: an Australian survey

    PubMed Central

    2013-01-01

    Background Little is known about the time spent on specific health related activities by older adult informal carers who assist people with chronic illness. Research has not yet addressed the association between carer health status and their care demands. Such information could inform policy and health system efforts to manage chronic illness. Methods We conducted an Australia wide survey using recall questionnaires to record time use. The study asked how much time is spent on “most days” for the most common activities like taking medication, self-treatment and testing, and how much time in the last month on less common activities like attending a physician or shopping associated with health needs. The survey was mailed to 5,000 members of National Seniors Australia; 2,500 registrants on the National Diabetes Services Scheme; and 3,100 members of the Australian Lung Foundation. A total of 2519 people responded, including 313 people who identified as informal carers. Statistical analysis was undertaken using Stata 11. Standard errors and confidence intervals were derived using bootstrapping techniques within Stata 11. Results Most carers (96.2%) had chronic illness themselves, and those with greater numbers of chronic illnesses were those who faced the greatest overall time demands. The top decile of carers devoted between 8.5 and 10 hours a day to personal and caring health related activities. Informal carers with chronic illness spent more time managing their own health than people with chronic illness who were not informal carers. These carers spent more time on caring for others than on caring for their own health. High levels of caring responsibility were associated with poorer reported carer health. Conclusions Policy and health care services will need to adapt to recognise and reduce the time burden on carers who themselves have chronic illness. More carefully targeted investment in the social infrastructure of formal care would free up carers for other

  9. 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.

  10. Evidence for sequential and increasing activation of replication origins along replication timing gradients in the human genome.

    PubMed

    Guilbaud, Guillaume; Rappailles, Aurélien; Baker, Antoine; Chen, Chun-Long; Arneodo, Alain; Goldar, Arach; d'Aubenton-Carafa, Yves; Thermes, Claude; Audit, Benjamin; Hyrien, Olivier

    2011-12-01

    Genome-wide replication timing studies have suggested that mammalian chromosomes consist of megabase-scale domains of coordinated origin firing separated by large originless transition regions. Here, we report a quantitative genome-wide analysis of DNA replication kinetics in several human cell types that contradicts this view. DNA combing in HeLa cells sorted into four temporal compartments of S phase shows that replication origins are spaced at 40 kb intervals and fire as small clusters whose synchrony increases during S phase and that replication fork velocity (mean 0.7 kb/min, maximum 2.0 kb/min) remains constant and narrowly distributed through S phase. However, multi-scale analysis of a genome-wide replication timing profile shows a broad distribution of replication timing gradients with practically no regions larger than 100 kb replicating at less than 2 kb/min. Therefore, HeLa cells lack large regions of unidirectional fork progression. Temporal transition regions are replicated by sequential activation of origins at a rate that increases during S phase and replication timing gradients are set by the delay and the spacing between successive origin firings rather than by the velocity of single forks. Activation of internal origins in a specific temporal transition region is directly demonstrated by DNA combing of the IGH locus in HeLa cells. Analysis of published origin maps in HeLa cells and published replication timing and DNA combing data in several other cell types corroborate these findings, with the interesting exception of embryonic stem cells where regions of unidirectional fork progression seem more abundant. These results can be explained if origins fire independently of each other but under the control of long-range chromatin structure, or if replication forks progressing from early origins stimulate initiation in nearby unreplicated DNA. These findings shed a new light on the replication timing program of mammalian genomes and provide a general

  11. Oscillatory phase modulates the timing of neuronal activations and resulting behavior.

    PubMed

    Coon, W G; Gunduz, A; Brunner, P; Ritaccio, A L; Pesaran, B; Schalk, G

    2016-06-01

    Human behavioral response timing is highly variable from trial to trial. While it is generally understood that behavioral variability must be due to trial-by-trial variations in brain function, it is still largely unknown which physiological mechanisms govern the timing of neural activity as it travels through networks of neuronal populations, and how variations in the timing of neural activity relate to variations in the timing of behavior. In our study, we submitted recordings from the cortical surface to novel analytic techniques to chart the trajectory of neuronal population activity across the human cortex in single trials, and found joint modulation of the timing of this activity and of consequent behavior by neuronal oscillations in the alpha band (8-12Hz). Specifically, we established that the onset of population activity tends to occur during the trough of oscillatory activity, and that deviations from this preferred relationship are related to changes in the timing of population activity and the speed of the resulting behavioral response. These results indicate that neuronal activity incurs variable delays as it propagates across neuronal populations, and that the duration of each delay is a function of the instantaneous phase of oscillatory activity. We conclude that the results presented in this paper are supportive of a general model for variability in the effective speed of information transmission in the human brain and for variability in the timing of human behavior. PMID:26975551

  12. Are Canadian Seniors Becoming More Active? Empirical Evidence Based on Time-Use Data

    ERIC Educational Resources Information Center

    Victorino, Charlemaigne C.; Gauthier, A. H.

    2005-01-01

    In this study, we examine trends in the patterns of time use of seniors in Canada since the 1980s. In particular, we ask whether today's seniors devote more, or less, time to productive activities than 20 years ago. Our inquiry is motivated by the claims that today's seniors are not engaged in "active aging." This study uses data from a series of…

  13. Exploring Time Allocation for Academic Activities by University Students in France

    ERIC Educational Resources Information Center

    Fernex, Alain; Lima, Laurent; de Vries, Erica

    2015-01-01

    The purpose of this article is to study how students allocate time to different university and extra-university activities and to identify factors that might explain variability both between and within fields of study. At the heart of this exercise is the question of the time students dedicate to academic activities in competition with a whole…

  14. Statistical Properties of Longitudinal Time-Activity Data for Use in Human Exposure Modeling

    EPA Science Inventory

    Understanding the longitudinal properties of the time spent in different locations and activities is important in characterizing human exposure to pollutants. The results of a four-season longitudinal time-activity diary study in eight working adults are presented, with the goal ...

  15. Constant illumination reduces circulating melatonin and impairs immune function in the cricket Teleogryllus commodus

    PubMed Central

    Michaelides, Ellie B.; Rupasinghe, Thusitha; Tull, Dedreia; Green, Mark P.; Jones, Therésa M.

    2015-01-01

    Exposure to constant light has a range of negative effects on behaviour and physiology, including reduced immune function in both vertebrates and invertebrates. It is proposed that the associated suppression of melatonin (a ubiquitous hormone and powerful antioxidant) in response to the presence of light at night could be an underlying mechanistic link driving the changes to immune function. Here, we investigated the relationship between constant illumination, melatonin and immune function, using a model invertebrate species, the Australian black field cricket, Teleogryllus commodus. Crickets were reared under either a 12 h light: 12 h dark regimen or a constant 24 h light regimen. Circulating melatonin concentration and immune function (haemocyte concentration, lytic activity and phenoloxidase (PO) activity) were assessed in individual adult crickets through the analysis of haemolymph. Constant illumination reduced melatonin and had a negative impact on haemocyte concentrations and lytic activity, but its effect on PO activity was less apparent. Our data provide the first evidence, to our knowledge, of a link between exposure to constant illumination and variation in haemocyte concentration in an invertebrate model, while also highlighting the potential complexity of the immune response following exposure to constant illumination. This study provides insight into the possible negative effect of artificial night-time lighting on the physiology of invertebrates, but whether lower and potentially more ecologically relevant levels of light at night produce comparable results, as has been reported in several vertebrate taxa, remains to be tested. PMID:26339535

  16. Beyond the Hubble Constant

    NASA Astrophysics Data System (ADS)

    1995-08-01

    spectrum was observed a few nights later with the EMMI instrument at the ESO NTT at La Silla. Further direct images were taken with EMMI and also with the high-resolution NTT SUSI camera, three of which are shown on the photo with text accompanying this Press Release. The supernova is located only 1 arcsecond from the centre of the parent galaxy. As the supernova was very faint (its magnitude was about 22.7, or about 5 million times fainter than what can be seen with the unaided eye), an exposure of 2.5 hours was necessary to collect enough photons to allow a classification of its spectrum. Because of the very small angular distance, the light from the supernova was heavily contaminated with that of the parent galaxy, but the excellent angular resolution of the NTT optics made it possible to overcome this problem. It was also possible to measure the redshift [2] of the galaxy (and thereby of the supernova) as 0.478. This demonstrates that SN 1995K is the most distant supernova (indeed, the most distant star!) ever observed [3]. The spectrum clearly showed SN 1995K to be of Type Ia. This is evident by a comparison with that of a ``standard'' Type Ia supernova (SN 1989B), cf. the graph with explanatory text attached to this Press Release. When the redshift of SN 1995K is taken into account, the two spectra are very similar. The current belief is that supernovae of this type are due to the explosions of white dwarf stars in compact binary systems which are triggered by the successive accretion of stellar material from the other component. As the sequence of NTT images shows, SN 1995K quickly faded and in late May 1995, it could no longer be observed. The rate of change (the ``light-curve'') also closely matched that of a normal Type Ia supernova. Why Are Type Ia Supernovae So Important? While supernovae are important astrophysical objects by themselves, Type Ia supernovae are also of great interest to cosmologists. The main reason is that they provide independent information

  17. Self-Reported Sitting Time, Physical Activity and Fibrinolytic and Other Novel Cardio-Metabolic Biomarkers in Active Swedish Seniors

    PubMed Central

    Howard, Bethany J.; Hurtig-Wennlöf, Anita; Olsson, Lovisa A.; Nilsson, Torbjörn K.; Dunstan, David W.; Wennberg, Patrik

    2016-01-01

    Background Too much sitting is linked with an increased risk of cardiovascular disease and mortality. The mediating mechanisms for these associations are largely unknown, however dysregulated fibrinolysis have emerged as a possible contributor. Objective We examined the associations of self-reported overall sitting time and physical activity with fibrinolytic and other novel cardio-metabolic biomarkers in older adults. Materials and Methods Data was analysed for 364 participants (74±7 yrs) of the Active Seniors group (retired, living independently in their own homes). Linear regression analyses examined associations of categories of categories of sitting time (≤3, 3–6, >6 hrs/day) and overall physical activity (Low, Moderate and High) with biomarkers in serum or plasma, adjusting for age, gender and smoking (with further adjustment for either overall physical activity or sitting time and BMI in secondary analyses). Results Compared to sitting ≤ 3 hrs/day, sitting >6 hrs/day was associated with higher tissue plasminogen activator (tPA) and tissue plasminogen activator/plasminogen activator inhibitor-1 complex (tPA-PAI-1 complex). These associations were not independent of overall physical activity or BMI. Compared to those in the high physical activity, low physical activity was associated with a higher BMI, high-sensitivity C-reactive protein (hs-CRP) and tPA-PAI-1 complex levels. Only the associations of BMI and hs-CRP were independent of sitting time. Conclusions These findings provide preliminary cross-sectional evidence for the relationships of sitting time with fibrinolytic markers in older adults. They also reinforce the importance of regular physical activity for cardio-metabolic health. PMID:27658041

  18. Activity patterns and time budgeting of Aplysia fasciata under field and laboratory conditions.

    PubMed

    Susswein, A J; Gev, S; Feldman, E; Markovich, S

    1983-11-01

    Activity patterns of Aplysia fasciata were observed in a protected port environment and in an aquarium. In both, major activities were feeding and mating, which collectively took up about 45% of the total time of the animals. Active behaviors occurred primarily at night; much of the day was spent in the inactive state. Activities were highly synchronized, with large numbers of animals performing the same behaviors simultaneously at a specific time. Mating and eating occurred primarily at different times; relatively few animals were observed performing these behaviors simultaneously. Many animals laying eggs were simultaneously mating as females.

  19. Motives for and barriers to physical activity in twin pairs discordant for leisure time physical activity for 30 years.

    PubMed

    Aaltonen, S; Leskinen, T; Morris, T; Alen, M; Kaprio, J; Liukkonen, J; Kujala, U

    2012-02-01

    Long-term persistent physical activity is important in the prevention of chronic diseases, but a large number of people do not participate in physical activity to obtain health benefits. The purpose of this study was to examine the motives and perceived barriers to long-term engagement in leisure time physical activity. Same-sex twin pairs (N=16, mean age 60) discordant for physical activity over 30 years were identified from the Finnish Twin Cohort. We evaluated participants' physical activity motivation with the 73-item Recreational Exercise Motivation Measure and assessed barriers to physical activity with a 25-item questionnaire. The characteristics of physical activity motivation and perceived barriers between the active and inactive co-twins were analysed using paired tests. Motives related to the sub-dimensions of enjoyment and physical fitness and psychological state were the most important reasons for participation in physical activity among all the twin individuals analysed. The sub-dimensions mastery (p=0.018, Cohen's d=0.76), physical fitness (p=0.029, Cohen's d=0.69), and psychological state (p=0.039, Cohen's d=0.65) differed significantly between active and inactive co-twins. More than half of the participants reported no reasons for not being physically active. If reasons existed, participation in physical activity was deterred mostly by pain and various health problems. This study found no differences in perceived barriers between active and inactive co-twins. We conclude from our results that the main factors promoting persistent leisure time physical activity were participants' wish to improve or maintain their physical skills or techniques, a feeling that exercise would improve their mental and physical health and that they found the activity enjoyable. This study helps us understand the importance of the role of motives and the minor role of perceived barriers for engagement in persistent physical activity. PMID:22318531

  20. Location, Timing, and Social Structure Patterns Related to Physical Activity Participation in Weight Loss Programs

    ERIC Educational Resources Information Center

    Gay, Jennifer L.; Trevarthen, Grace

    2013-01-01

    Less than half of the adults in the United States meet national guidelines for physical activity. Physical activity programs can induce short-term improvements in physical activity. To develop effective interventions, researchers and practitioners should consider the timing, location, and social structure patterns of participants. Using a pretest,…

  1. Educational Activities for the Life Over Time Exhibit at The Field Museum.

    ERIC Educational Resources Information Center

    Laraba, Peter; Wickland, Thomas J.

    The activities presented in this book, designed to help 4th through 8th grade instructors teach about the history of life, help students prepare for a visit to a museum exhibit on life through time. The pre- and post-visit activities as well as the in-museum activities help students prepare for and enjoy their 4.5 billion year trip through time at…

  2. Developmental patterns and parental correlates of youth leisure-time physical activity.

    PubMed

    Lam, Chun Bun; McHale, Susan M

    2015-02-01

    This study examined the developmental patterns and parental correlates of youth leisure-time physical activity from middle childhood through adolescence. On 5 occasions across 7 years, fathers, mothers, and children who were first- and second born from 201 European American, working- and middle-class families participated in home and multiple nightly phone interviews. Multilevel modeling revealed that, controlling for family socioeconomic status, neighborhood characteristics, and youth overweight status and physical health, leisure-time physical activity increased during middle childhood and declined across adolescence, and the decline was more pronounced for girls than for boys. Moreover, controlling for time-varying, parental work hours and youth interest in sports and outdoor activities, on occasions when fathers and mothers spent proportionally more time on these activities with youth than usual, youth also spent more total time on these activities than usual. The within-person association between mother-youth joint involvement and youth's total involvement in leisure-time physical activity reached statistical significance at the transition to adolescence, and became stronger over time. Findings highlight the importance of maintaining adolescents', especially girls', physical activity levels and targeting both fathers' and mothers' involvement to promote youth's physical activity.

  3. Absolute radiometry and the solar constant

    NASA Technical Reports Server (NTRS)

    Willson, R. C.

    1974-01-01

    A series of active cavity radiometers (ACRs) are described which have been developed as standard detectors for the accurate measurement of irradiance in absolute units. It is noted that the ACR is an electrical substitution calorimeter, is designed for automatic remote operation in any environment, and can make irradiance measurements in the range from low-level IR fluxes up to 30 solar constants with small absolute uncertainty. The instrument operates in a differential mode by chopping the radiant flux to be measured at a slow rate, and irradiance is determined from two electrical power measurements together with the instrumental constant. Results are reported for measurements of the solar constant with two types of ACRs. The more accurate measurement yielded a value of 136.6 plus or minus 0.7 mW/sq cm (1.958 plus or minus 0.010 cal/sq cm per min).

  4. Cosmological constant in scale-invariant theories

    SciTech Connect

    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.

  5. Non-Formal Education in Free Time: Leisure- or Work-Orientated Activity?

    ERIC Educational Resources Information Center

    Thoidis, Ioannis; Pnevmatikos, Dimitrios

    2014-01-01

    This article deals with the relationship between adults' free time and further education. More specifically, the paper addresses the question of whether there are similarities and analogies between the leisure time that adults dedicate to non-formal educational activities and free time per se. A structured questionnaire was used to examine…

  6. Revisiting the Time Trade-off Hypothesis: Work, Organized Activities, and Academics during College

    PubMed Central

    Maggs, Jennifer L.

    2014-01-01

    How adolescents spend their time has long-term implications for their educational, health, and labor market outcomes, yet surprisingly little research has explored the time use of students across days and semesters. The current study used longitudinal daily diary data from a sample of college students attending a large public university in the Northeastern US (n = 726, Mage = 18.4) that was followed for 14 days within each of 7 semesters (for up to 98 diary days per student). The study had two primary aims. The first aim was to explore demographic correlates of employment time, organized activity time, and academic time. The second aim was to provide a rigorous test of the time trade-off hypothesis, which suggests that students will spend less time on academics when they spend more time on employment and extracurricular activities. The results demonstrated that time use varied by gender, parental education, and race/ethnicity. Furthermore, the results from multi-level models provided some support for the time trade-off hypothesis, although associations varied by the activity type and whether the day was a weekend. More time spent on employment was linked to less time spent on academics across days and semesters whereas organized activities were associated with less time on academics at the daily level only. The negative associations between employment and academics were most pronounced on weekdays. These results suggest that students may balance certain activities across days, whereas other activities may be in competition over longer time frames (i.e., semesters). PMID:25381597

  7. Restricting opportunities to be active during school time: do children compensate by increasing physical activity levels after school?

    PubMed

    Dale, D; Corbin, C B; Dale, K S

    2000-09-01

    Opportunities for children to be physically active during school time are sparse and becoming increasingly so. The purpose of this investigation was to determine if children would compensate for school days (9 a.m.-3 p.m.) of restricted physical activity opportunities by increasing activity levels after school (3 p.m.-7:30 p.m.). Third and fourth grade children (N = 76) each wore a CSA accelerometer for 4 nonconsecutive days. Two days were categorized as active--during school, all children participated in outdoor recess and physical education class. Two days were categorized as restricted--all children spent their recess time indoors at a computer terminal, and no physical education class was scheduled. Dependent t tests revealed that children did not compensate for a sedentary school day by increasing their levels of physical activity after school. In fact, average movement counts per minute were higher in the 3 p.m.-7:30 p.m. period following the active day (525 counts.min-1) versus the restricted day (186 counts.min-1). These findings suggest cause for concern if children's opportunities to be active within school time are limited. Several reasons are given as to why children did not compensate or "make up" for the physical activity opportunities missed during the restricted school day.

  8. 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.

  9. Thermally activated switching at long time scales in exchange-coupled magnetic grains

    NASA Astrophysics Data System (ADS)

    Almudallal, Ahmad M.; Mercer, J. I.; Whitehead, J. P.; Plumer, M. L.; van Ek, J.; Fal, T. J.

    2015-10-01

    Rate coefficients of the Arrhenius-Néel form are calculated for thermally activated magnetic moment reversal for dual layer exchange-coupled composite (ECC) media based on the Langer formalism and are applied to study the sweep rate dependence of M H hysteresis loops as a function of the exchange coupling I between the layers. The individual grains are modeled as two exchange-coupled Stoner-Wohlfarth particles from which the minimum energy paths connecting the minimum energy states are calculated using a variant of the string method and the energy barriers and attempt frequencies calculated as a function of the applied field. The resultant rate equations describing the evolution of an ensemble of noninteracting ECC grains are then integrated numerically in an applied field with constant sweep rate R =-d H /d t and the magnetization calculated as a function of the applied field H . M H hysteresis loops are presented for a range of values I for sweep rates 105Oe /s ≤R ≤1010Oe /s and a figure of merit that quantifies the advantages of ECC media is proposed. M H hysteresis loops are also calculated based on the stochastic Landau-Lifshitz-Gilbert equations for 108Oe /s ≤R ≤1010Oe /s and are shown to be in good agreement with those obtained from the direct integration of rate equations. The results are also used to examine the accuracy of certain approximate models that reduce the complexity associated with the Langer-based formalism and which provide some useful insight into the reversal process and its dependence on the coupling strength and sweep rate. Of particular interest is the clustering of minimum energy states that are separated by relatively low-energy barriers into "metastates." It is shown that while approximating the reversal process in terms of "metastates" results in little loss of accuracy, it can reduce the run time of a kinetic Monte Carlo (KMC) simulation of the magnetic decay of an ensemble of dual layer ECC media by 2 -3 orders of magnitude

  10. Trade-offs between commuting time and health-related activities.

    PubMed

    Christian, Thomas J

    2012-10-01

    To further understand documented associations between obesity and urban sprawl, this research describes individuals' trade-offs between health-related activities and commuting time. A cross-section of 24,861 working-age individuals employed full-time and residing in urban counties is constructed from the American Time Use Survey (2003-2010). Data are analyzed using seemingly unrelated regressions to quantify health-related activity decreases in response to additional time spent commuting. Outcomes are total daily minutes spent in physical activity at a moderate or greater intensity, preparing food, eating meals with family, and sleeping. Commuting time is measured as all travel time between home and work and vice versa. The mean commuting time is 62 min daily, the median is 55 min, and 10.1% of workers commute 120 min or more. Spending an additional 60 min daily commuting above average is associated with a 6% decrease in aggregate health-related activities and spending an additional 120 min is associated with a 12% decrease. The greatest percentage of commuting time comes from sleeping time reductions (28-35%). Additionally, larger proportions of commuting time are taken from physical activity and food preparation relative to the mean commuting length: of 60 min spent commuting, 16.1% is taken from physical activity and 4.1% is taken from food preparation; of 120 min commuting, 20.3% is taken from physical activity and 5.6% is taken from food preparation. The results indicate that longer commutes are associated with behavioral patterns which over time may contribute to obesity and other poor health outcomes. These findings will assist both urban planners and researchers wishing to understand time constraints' impacts on health. PMID:22689293

  11. Leisure Time Physical Activity and Mortality: A Detailed Pooled Analysis of the Dose-Response Relationship

    PubMed Central

    Arem, Hannah; Moore, Steven C.; Patel, Alpa; Hartge, Patricia; de Gonzalez, Amy Berrington; Visvanathan, Kala; Campbell, Peter T.; Freedman, Michal; Weiderpass, Elisabete; Adami, Hans Olov; Linet, Martha S.; Lee, I-Min; Matthews, Charles E.

    2015-01-01

    Importance The 2008 Physical Activity Guidelines for Americans recommended a minimum of 75 vigorous-intensity or 150 moderate-intensity minutes per week (7.5 metabolic equivalent hours per week (MET h/wk)) of aerobic activity for “substantial” health benefit, and suggested “additional” benefits by doing more than double this amount. However, the upper limit of longevity benefit or possible harm with more physical activity is unclear. Objective To quantify the dose-response association between leisure-time physical activity and mortality, and to define the upper limit of benefit or harm associated with more physical activity. Design We pooled data from six studies in the NCI Cohort Consortium (baseline 1992–2003). We used Cox proportional hazards regression with cohort stratification to generate multivariable-adjusted hazard ratios (HR) and 95% confidence intervals (CI). Median follow-up time was 14.2 years. Setting Population-based prospective cohorts in the U.S. and Europe with self-reported physical activity. Participants 661,137 men and women (116,686 deaths); median age 62 (range 21–98) years. Exposure Leisure-time moderate- to vigorous-intensity physical activity Main Outcome Mortality Results Compared to those reporting no leisure-time physical activity, we observed a 20% lower mortality risk among those performing less than the recommended 7.5 MET h/wk minimum (HR=0.80, 95% CI 0.78–0.82), a 31% lower risk at 1–2 times the recommended minimum (0.69, 0.67–0.70), and a 37% lower risk at 2–3 times the minimum (0.63, 0.62–0.65). An upper threshold for mortality benefit occurred at 3–5 times the physical activity recommendation (0.61, 0.59–0.62), but compared to the recommended minimum, the additional benefit was modest (31% vs. 39%). There was no evidence of harm at 10+ times the recommended minimum (0.68, 0.59–0.78). A similar dose-response was observed for mortality due to cardiovascular disease and to cancer. Conclusions and

  12. Time-resolved observation of thermally activated rupture of a capillary-condensed water nanobridge

    SciTech Connect

    Bak, Wan; Sung, Baekman; Kim, Jongwoo; Kwon, Soyoung; Kim, Bongsu; Jhe, Wonho

    2015-01-05

    The capillary-condensed liquid bridge is one of the most ubiquitous forms of liquid in nature and contributes significantly to adhesion and friction of biological molecules as well as microscopic objects. Despite its important role in nanoscience and technology, the rupture process of the bridge is not well understood and needs more experimental works. Here, we report real-time observation of rupture of a capillary-condensed water nanobridge in ambient condition. During slow and stepwise stretch of the nanobridge, we measured the activation time for rupture, or the latency time required for the bridge breakup. By statistical analysis of the time-resolved distribution of activation time, we show that rupture is a thermally activated stochastic process and follows the Poisson statistics. In particular, from the Arrhenius law that the rupture rate satisfies, we estimate the position-dependent activation energies for the capillary-bridge rupture.

  13. Objectively measured physical activity and sedentary time in European adolescents: the HELENA study.

    PubMed

    Ruiz, Jonatan R; Ortega, Francisco B; Martínez-Gómez, David; Labayen, Idoia; Moreno, Luis A; De Bourdeaudhuij, Ilse; Manios, Yannis; Gonzalez-Gross, Marcela; Mauro, Beatrice; Molnar, Denes; Widhalm, Kurt; Marcos, Ascensión; Beghin, Laurent; Castillo, Manuel J; Sjöström, Michael

    2011-07-15

    The authors' aim in this cross-sectional study was to characterize levels of objectively measured physical activity and sedentary time in adolescents from 9 European countries. The study comprised 2,200 European adolescents (1,184 girls) participating in the HELENA cross-sectional study (2006-2008). Physical activity was measured by accelerometry and was expressed as average intensity (counts/minute) and amount of time (minutes/day) spent engaging in moderate- to vigorous-intensity physical activity (MVPA). Time spent in sedentary behaviors was also objectively measured. Cardiorespiratory fitness was measured by means of the 20-m shuttle run test. Level of maternal education was reported by the adolescents. A higher proportion of boys (56.8% of boys vs. 27.5% of girls) met the physical activity recommendations of at least 60 minutes/day of MVPA. Adolescents spent most of the registered time in sedentary behaviors (9 hours/day, or 71% of the registered time). Both average intensity and MVPA were higher in adolescents with high cardiorespiratory fitness, and sedentary time was lower in the high-fitness group. There were no physical activity or sedentary time differences between maternal education categories. These data provide an objective measure of physical activity and amount of time spent in sedentary behaviors in a relatively large number of European adolescents.

  14. Summary of the Effort to Use Active-induced Time Correlation Techniques to Measure the Enrichment of HEU

    SciTech Connect

    McConchie, Seth M.; Crye, Jason Michael; Pena, Kirsten; Sword, Eric; Mihalczo, John T.

    2015-09-30

    This document summarizes the effort to use active-induced time correlation techniques to measure the enrichment of bulk quantities of enriched uranium. In summary, these techniques use an external source to initiate fission chains, and the time distribution of the detected fission chain neutrons is sensitive to the fissile material enrichment. The number of neutrons emitted from a chain is driven by the multiplication of the item, and the enrichment is closely coupled to the multiplication of the item. As the enrichment increases (decreases), the multiplication increases (decreases) if the geometry is held constant. The time distribution of fission chain neutrons is a complex function of the enrichment and material configuration. The enrichment contributes to the probability of a subsequent fission in a chain via the likelihood of fissioning on an even-numbered isotope versus an odd-numbered isotope. The material configuration contributes to the same probability via solid angle effects for neutrons inducing subsequent fissions and the presence of any moderating material. To simplify the ability to accurately measure the enrichment, an associated particle imaging (API) D-T neutron generator and an array of plastic scintillators are used to simultaneously image the item and detect the fission chain neutrons. The image is used to significantly limit the space of enrichment and material configuration and enable the enrichment to be determined unambiguously.

  15. Motivation and Barriers for Leisure-Time Physical Activity in Socioeconomically Disadvantaged Women

    PubMed Central

    Santos, Inês; Ball, Kylie; Crawford, David; Teixeira, Pedro J.

    2016-01-01

    Introduction The aim of this study was to examine cross-sectional and longitudinal associations between motivation and barriers for physical activity, and physical activity behavior in women living in socioeconomic disadvantage. This study also examined whether weight control intentions moderate those associations. Methods Data from 1664 women aged 18–46 years was collected at baseline and three-year follow-up as part of the Resilience for Eating and Activity Despite Inequality study. In mail-based surveys, women reported sociodemographic and neighborhood environmental characteristics, intrinsic motivation, goals and perceived family barriers to be active, weight control intentions and leisure-time physical activity (assessed through the IPAQ-L). Linear regression models assessed the association of intrinsic motivation, goals and barriers with physical activity at baseline and follow-up, adjusting for environmental characteristics and also physical activity at baseline (for longitudinal analyses), and the moderating effects of weight control intentions were examined. Results Intrinsic motivation and, to a lesser extent, appearance and relaxation goals for being physically active were consistently associated with leisure-time physical activity at baseline and follow-up. Perceived family barriers, health, fitness, weight and stress relief goals were associated with leisure-time physical activity only at baseline. Moderated regression analyses revealed that weight control intentions significantly moderated the association between weight goals and leisure-time physical activity at baseline (β = 0.538, 99% CI = 0.057, 0.990) and between intrinsic motivation and leisure-time physical activity at follow-up (β = 0.666, 99% CI = 0.188, 1.145). For women actively trying to control their weight, intrinsic motivation was significantly associated with leisure-time physical activity at follow-up (β = 0.184, 99% CI = 0.097, 0.313). Conclusions Results suggest that

  16. Physical Activity Measurement Device Agreement: Pedometer Steps/Minute and Physical Activity Time

    ERIC Educational Resources Information Center

    Scruggs, Philip W.; Mungen, Jonathan D.; Oh, Yoonsin

    2010-01-01

    The purpose of this study was to examine agreement between the Walk4Life DUO pedometer (W4L; Walk4Life, Plainfield, Illinois, USA) and two criterion instruments in the measurement of physical activity. Participants (N = 189, M = 16.74 years, SD = 0.99) in high school physical education concurrently wore the DUO (i.e., comparison instrument) and…

  17. Direct measurement of activation time and nucleation rate in capillary-condensed water nanomeniscus

    SciTech Connect

    Sung, Baekman; Kim, Jongwoo; Stambaugh, Corey; Chang, Sung-Jin; Jhe, Wonho

    2013-11-18

    We demonstrate real-time observation of nucleation of the single water nanomeniscus formed via capillary condensation. We directly measure (i) activation time by time-resolved atomic force microscopy and (ii) nucleation rate by statistical analysis of its exponential distribution, which is the experimental evidence that the activation process is stochastic and follows the Poisson statistics. It implies that formation of the water nanomeniscus is triggered by nucleation, which requires activation for producing a nucleus. We also find the dependence of the nucleation rate on the tip-sample distance and temperature.

  18. Revisiting the question: Does high-latitude solar activity lead low-latitude solar activity in time phase?

    SciTech Connect

    Kong, D. F.; Qu, Z. N.; Guo, Q. L.

    2014-05-01

    Cross-correlation analysis and wavelet transform methods are used to investigate whether high-latitude solar activity leads low-latitude solar activity in time phase or not, using the data of the Carte Synoptique solar filaments archive from 1919 March to 1989 December. From the cross-correlation analysis, high-latitude solar filaments have a time lead of 12 Carrington solar rotations with respect to low-latitude ones. Both the cross-wavelet transform and wavelet coherence indicate that high-latitude solar filaments lead low-latitude ones in time phase. Furthermore, low-latitude solar activity is better correlated with high-latitude solar activity of the previous cycle than with that of the following cycle, which is statistically significant. Thus, the present study confirms that high-latitude solar activity in the polar regions is indeed better correlated with the low-latitude solar activity of the following cycle than with that of the previous cycle, namely, leading in time phase.

  19. Effects of reaction time variability and age on brain activity during Stroop task performance.

    PubMed

    Tam, Angela; Luedke, Angela C; Walsh, Jeremy J; Fernandez-Ruiz, Juan; Garcia, Angeles

    2015-09-01

    Variability in reaction time during task performance may reflect fluctuations in attention and cause reduced performance in goal-directed tasks, yet it is unclear whether the mechanisms behind this phenomenon change with age. Using fMRI, we tested young and cognitively healthy older adults with the Stroop task to determine whether aging affects the neural mechanisms underlying intra-individual reaction time variability. We found significant between-group differences in BOLD activity modulated by reaction time. In older adults, longer reaction times were associated with greater activity in frontoparietal attentional areas, while in younger adults longer reaction times were associated with greater activity in default mode network areas. Our results suggest that the neural correlates of reaction time variability change with healthy aging, reinforcing the concept of functional plasticity to maintain high cognitive function throughout the lifespan.

  20. Softening of infrared-active mode of perovskite BaZrO{sub 3} proved by terahertz time-domain spectroscopy

    SciTech Connect

    Helal, M. A.; Mori, T.; Kojima, S.

    2015-05-04

    The low-frequency infrared-active optical modes were studied in a barium zirconate, BaZrO{sub 3}, single crystal with the perovskite structure using terahertz (THz) time-domain spectroscopy (TDS). The real and imaginary parts of the dielectric constants were accurately determined in the frequency range between 0.2 and 2.7 THz. Upon cooling from room temperature to 8 K, the lowest-frequency TO1 mode at 2.32 THz showed a pronounced softening to 1.94 THz. The real part of the dielectric constant at 0.5 THz determined by THz-TDS obeys Barrett's relation, and the existence of a plateau confirms that the quantum effects lead to saturation of the soft mode frequencies of the TO1 and TO2 modes below ≈20 K. This is reminiscent of incipient ferroelectrics with the perovskite structure such as CaTiO{sub 3}.

  1. Leisure-time physical activity and psychological well-being in university students.

    PubMed

    Molina-García, J; Castillo, I; Queralt, A

    2011-10-01

    An analysis of psychological well-being (self-esteem and subjective vitality) of 639 Spanish university students was performed, while accounting for the amount of leisure-time physical activity. The Spanish versions of the Rosenberg Self-Esteem Scale and Subjective Vitality Scale were employed. Participants were divided into four groups (Low, Moderate, High, and Very high) depending on estimation of energy expenditure in leisure-time physical activity. Men and women having higher physical activity rated higher mean subjective vitality; however, differences in self-esteem were observed only in men, specifically between Very high and the other physical activity groups. PMID:22238852

  2. Leisure-time physical activity and psychological well-being in university students.

    PubMed

    Molina-García, J; Castillo, I; Queralt, A

    2011-10-01

    An analysis of psychological well-being (self-esteem and subjective vitality) of 639 Spanish university students was performed, while accounting for the amount of leisure-time physical activity. The Spanish versions of the Rosenberg Self-Esteem Scale and Subjective Vitality Scale were employed. Participants were divided into four groups (Low, Moderate, High, and Very high) depending on estimation of energy expenditure in leisure-time physical activity. Men and women having higher physical activity rated higher mean subjective vitality; however, differences in self-esteem were observed only in men, specifically between Very high and the other physical activity groups.

  3. Human intracranial high-frequency activity maps episodic memory formation in space and time.

    PubMed

    Burke, John F; Long, Nicole M; Zaghloul, Kareem A; Sharan, Ashwini D; Sperling, Michael R; Kahana, Michael J

    2014-01-15

    Noninvasive neuroimaging studies have revealed a network of brain regions that activate during human memory encoding; however, the relative timing of such activations remains unknown. Here we used intracranially recorded high-frequency activity (HFA) to first identify regions that activate during successful encoding. Then, we leveraged the high-temporal precision of HFA to investigate the timing of such activations. We found that memory encoding invokes two spatiotemporally distinct activations: early increases in HFA that involve the ventral visual pathway as well as the medial temporal lobe and late increases in HFA that involve the left inferior frontal gyrus, left posterior parietal cortex, and left ventrolateral temporal cortex. We speculate that these activations reflect higher-order visual processing and top-down modulation of attention/semantic information, respectively.

  4. Synthesis of Mannich bases: 2-(3-Phenylaminopropionyloxy)-benzoic acid and 3-Phenylamino-1-(2,4,6-trimethoxy-phenyl)-propan-1-one, their toxicity, ionization constant, antimicrobial and antioxidant activities.

    PubMed

    Oloyede, Ganiyat K; Willie, Itoro E; Adeeko, Oluwakemi O

    2014-12-15

    Mannich bases 2-(3-Phenylaminopropionyloxy)-benzoic acid (A) and 3-Phenylamino-1-(2,4,6-trimethoxy-phenyl)-propan-1-one (B) were synthesized. Structures were confirmed by ultraviolet/visible and infra-red spectroscopies. The ionization constant (pKa) values at 8.3 and 8.0 reported for compounds A and B, respectively, indicated that protonation might occur at physiological pH. The LC50 values of 145,595 μg/ml (A) and 82,526 μg/ml (B) obtained from Brine shrimp lethality testing showed that both compounds were non-toxic. The two compounds possessed significant antimicrobial activity against bacterial and fungal strains; Escherichia coli, Staphylococcus aereus, Bacillus subtilis, Pseudomonas aeruginosa, Klebsiella pneumoniae, Salmonellae typhi, Candida albicans, Rhizopus stolonifer, Aspergillus niger and Penicillium notatum when compared with standards, gentamicin and tioconazole for bacteria and fungi, respectively. In vitro antioxidant screening by the DPPH free radical scavenging method and the scavenging effect on hydrogen peroxide showed that the compounds possessed significant antioxidant activity when compared with antioxidant standards ascorbic acid, butylated hydroxylanisole and α-tocopherol. PMID:25038706

  5. Time Use and Physical Activity: A Shift Away from Movement across the Globe

    PubMed Central

    Ng, Shu Wen; Popkin, Barry

    2012-01-01

    Technology linked with reduced physical activity (PA) in occupational work, home/domestic work, and travel and increased sedentary activities, especially television viewing, dominates the globe. Using detailed historical data on time allocation, occupational distributions, energy expenditures data by activity, and time-varying measures of metabolic equivalents of task (MET) for activities when available, we measure historical and current MET by four major PA domains (occupation, home production, travel, and active leisure) and sedentary time among adults (> 18 years). Trends by domain for the United States (1965–2009), the United Kingdom (1961–2005), Brazil (2002–2007), China (1991–2009), and India (2000–2005) are presented. We also project changes in energy expenditure by domain and sedentary time (excluding sleep and personal care) to 2020 and 2030 for each of these countries. The use of previously unexplored detailed time allocation and energy expenditures and other datasets represents a useful addition to our ability to document activity and inactivity globally. Given the potential impact on weight gain and other cardiometabolic health risks, the differential declines in MET of activity and increases in sedentary time across the globe represents a major threat to global health. PMID:22694051

  6. Real-time fMRI-based activation analysis and stimulus control

    NASA Astrophysics Data System (ADS)

    Moench, Tobias; Hollmann, Maurice; Bernarding, Johannes

    2007-03-01

    The real-time analysis of brain activation using functional MRI data offers a wide range of new experiments such as investigating self-regulation or learning strategies. However, besides special data acquisition and real-time data analysing techniques such examination requires dynamic and adaptive stimulus paradigms and self-optimising MRI-sequences. This paper presents an approach that enables the unified handling of parameters influencing the different software systems involved in the acquisition and analysing process. By developing a custom-made Experiment Description Language (EDL) this concept is used for a fast and flexible software environment which treats aspects like extraction and analysis of activation as well as the modification of the stimulus presentation. We describe how extracted real-time activation is subsequently evaluated by comparing activation patterns to previous acquired templates representing activated regions of interest for different predefined conditions. According to those results the stimulus presentation is adapted. The results showed that the developed system in combination with EDL is able to reliably detect and evaluate activation patterns in real-time. With a processing time for data analysis of about one second the approach is only limited by the natural time course of the hemodynamic response function of the brain activation.

  7. Seasonal variation in physical activity and sedentary time in different European regions. The HELENA study.

    PubMed

    Gracia-Marco, Luis; Ortega, Francisco B; Ruiz, Jonatan R; Williams, Craig A; Hagströmer, Maria; Manios, Yannis; Kafatos, Anthony; Béghin, Laurent; Polito, Angela; De Henauw, Stefaan; Valtueña, Jara; Widhalm, Kurt; Molnar, Denes; Alexy, Ute; Moreno, Luis A; Sjöström, Michael

    2013-01-01

    This report aims (1) to examine the association between seasonality and physical activity (PA) and sedentary time in European adolescents and (2) to investigate whether this association was influenced by geographical location (Central-North versus South of Europe), which implies more or less extreme weather and daylight hours. Valid data on PA, sedentary time and seasonality were obtained in 2173 adolescents (1175 females; 12.5-17.5 years) included in this study. Physical activity and sedentary time were measured by accelerometers. ANCOVA was conducted to analyse the differences in PA and sedentary time across seasons. Results showed that girls had lower levels of moderate to vigorous PA (MVPA) and average PA, and spent more time in sedentary activities in winter compared with spring (all P < 0.05). Stratified analyses showed differences in PA and sedentary time between winter and spring in European girls from Central-North of Europe (P < 0.05 for sedentary time). There were no differences between PA and sedentary time across seasonality in boys. In conclusion, winter is related with less time spent in MVPA, lower average PA and higher time spent in sedentary activities in European adolescent girls, compared with spring. These differences seem to mainly occur in Central-North Europe.

  8. Correlates of children's time-specific physical activity: a review of the literature.

    PubMed

    Stanley, Rebecca M; Ridley, Kate; Dollman, James

    2012-01-01

    Assessment of correlates of physical activity occurring at different times of the day, locations and contexts, is imperative to understanding children's physical activity behaviour. The purpose of this review was to identify the correlates of children's physical activity (aged 8-14 years) occurring during the school break time and after-school periods. A review was conducted of the peer-reviewed literature, published between 1990 and January 2011. A total of 22 studies (12 school break time studies, 10 after-school studies) were included in the review. Across the 22 studies, 17 studies were cross-sectional and five studies were interventions. In the school break time studies, 39 potential correlates were identified, of which gender and age were consistently associated with school break time physical activity in two or more studies, and family affluence, access to a gym, access to four or more physical activity programs and the condition of a playing field were all associated with school break time physical activity in only one study. Access to loose and fixed equipment, playground markings, size of and access to play space and the length of school break time were all positively associated with changes in school break time physical activity in intervention studies. Thirty-six potential correlates of after-school physical activity were identified. Gender (with boys more active), younger age, lower body mass index (for females), lower TV viewing/playing video games, and greater access to facilities were associated with higher levels of after-school physical activity in two or more studies. Parent supervision was negatively associated with females' after-school physical activity in one study. This review has revealed a relatively small number of studies investigating the school break time and after-school periods in the specified age range and only a few correlates have demonstrated a consistent association with physical activity. This highlights the infancy of this

  9. Physical activity and sedentary time: male perceptions in a university work environment.

    PubMed

    George, Emma S; Kolt, Gregory S; Rosenkranz, Richard R; Guagliano, Justin M

    2014-03-01

    Promoting physical activity and reducing sedentary time in males can be challenging, and interventions tailored specifically for males are limited. Understanding male perceptions of physical activity and sedentary behavior is important to inform development of relevant interventions, especially for males working in an office setting. As part of a larger intervention study to increase physical activity and reduce sedentary time, male university employees aged 35 to 64 years were invited to partake in focus groups to discuss benefits, motivators, and barriers related to physical activity and sedentary time. Five semistructured focus group sessions, ranging from 50 to 70 minutes in duration, were conducted on two campuses at an Australian university. A total of 15 participants (9 academic/faculty staff and 6 professional staff), with a mean (± SD) age of 46.1 (±8.0) years took part in the study. Health and family were commonly discussed motivators for physical activity, whereas time constraints and work commitments were major barriers to physical activity participation. Sedentary time was a perceived "by-product" of participants' university employment, as a substantial proportion of their days were spent sitting, primarily at a computer. Participants believed that physical activity should be recognized as a legitimate activity at work, embedded within the university culture and endorsed using a top-down approach. It is important to encourage breaks in sedentary time and recognize physical activity as a legitimate health-promoting activity that is supported and encouraged during working hours. These findings can be used as a platform from which to develop targeted strategies to promote physical activity in male university employees.

  10. Phase advancement and nucleus-specific timing of thalamocortical activity during slow cortical oscillation

    PubMed Central

    Slézia, Andrea; Hangya, Balázs; Ulbert, István; Acsády, László

    2011-01-01

    The exact timing of cortical afferent activity is instrumental for the correct coding and retrieval of internal and external stimuli. Thalamocortical inputs represent the most significant subcortical pathway to the cortex, but the precise timing and temporal variability of thalamocortical activity is not known. To examine this question, we studied the phase of thalamic action potentials relative to cortical oscillations and established correlations among phase, the nuclear location of the thalamocortical neurons and the frequency of cortical activity. The phase of thalamic action potentials depended on the exact frequency of the slow cortical oscillation both on long (minutes) and short (single wave) time scales. Faster waves were accompanied by phase advancement in both cases. Thalamocortical neurons located in different nuclei fired at significantly different phases of the slow waves but were active at similar phase of spindle oscillations. Different thalamic nuclei displayed distinct burst patterns. Bursts with higher number of action potentials displayed progressive phase advancement in a nucleus-specific manner. Thalamic neurons located along nuclear borders were characterized by mixed burst and phase properties. Our data demonstrate that the temporal relationship between cortical and thalamic activity is not fixed but displays dynamic changes during oscillatory activity. The timing depends on the precise location and exact activity of thalamocortical cells and the ongoing cortical network pattern. This variability of thalamic output and its coupling to cortical activity can enable thalamocortical neurons to actively participate in the coding and retrieval of complex cortical signals. PMID:21228169

  11. A DNA Sequence Element That Advances Replication Origin Activation Time in Saccharomyces cerevisiae

    PubMed Central

    Pohl, Thomas J.; Kolor, Katherine; Fangman, Walton L.; Brewer, Bonita J.; Raghuraman, M. K.

    2013-01-01

    Eukaryotic origins of DNA replication undergo activation at various times in S-phase, allowing the genome to be duplicated in a temporally staggered fashion. In the budding yeast Saccharomyces cerevisiae, the activation times of individual origins are not intrinsic to those origins but are instead governed by surrounding sequences. Currently, there are two examples of DNA sequences that are known to advance origin activation time, centromeres and forkhead transcription factor binding sites. By combining deletion and linker scanning mutational analysis with two-dimensional gel electrophoresis to measure fork direction in the context of a two-origin plasmid, we have identified and characterized a 19- to 23-bp and a larger 584-bp DNA sequence that are capable of advancing origin activation time. PMID:24022751

  12. Physical Activity Energy Expenditure in Dutch Adolescents: Contribution of Active Transport to School, Physical Education, and Leisure Time Activities

    ERIC Educational Resources Information Center

    Slingerland, Menno; Borghouts, Lars B.; Hesselink, Matthijs K. C.

    2012-01-01

    Background: Detailed knowledge about physical activity energy expenditure (PAEE) can guide the development of school interventions aimed at reducing overweight in adolescents. However, relevant components of PAEE have never been objectively quantified in this population. This study investigated the contribution of active transport to and from…

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

    PubMed

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

    1992-05-01

    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.

  14. 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

  15. Measuring enjoyment of physical activity in older adults: invariance of the physical activity enjoyment scale (paces) across groups and time

    PubMed Central

    2011-01-01

    The purpose of this study was to validate the Physical Activity Enjoyment Scale (PACES) in a sample of older adults. Participants within two different exercise groups were assessed at two time points, 6 months apart. Group and longitudinal invariance was established for a novel, 8-item version of the PACES. The shortened, psychometrically sound measure provides researchers and practitioners an expedited and reliable instrument for assessing the enjoyment of physical activity. PMID:21951520

  16. Objectively measured sedentary time and physical activity in women with fibromyalgia: a cross-sectional study

    PubMed Central

    Ruiz, Jonatan R; Segura-Jiménez, Víctor; Ortega, Francisco B; Álvarez-Gallardo, Inmaculada C; Camiletti-Moirón, Daniel; Aparicio, Virginia A; Carbonell-Baeza, Ana; Femia, Pedro; Munguía-Izquierdo, Diego; Delgado-Fernández, Manuel

    2013-01-01

    Objectives To characterise levels of objectively measured sedentary time and physical activity in women with fibromyalgia. Design Cross-sectional study. Setting Local Association of Fibromyalgia (Granada, Spain). Participants The study comprised 94 women with diagnosed fibromyalgia who did not have other severe somatic or psychiatric disorders, or other diseases that prevent physical loading, able to ambulate and to communicate and capable and willing to provide informed consent. Primary outcome measures Sedentary time and physical activity were measured by accelerometry and expressed as time spent in sedentary behaviours, average physical activity intensity (counts/minute) and amount of time (minutes/day) spent in moderate intensity and in moderate-to-vigorous-intensity physical activity (MVPA). Results The proportion of women meeting the physical activity recommendations of 30 min/day of MVPA on 5 or more days a week was 60.6%. Women spent, on average, 71% of their waking time (approximately 10 h/day) in sedentary behaviours. Both sedentary behaviour and physical activity levels were similar across age groups, waist circumference and percentage body fat categories, years since clinical diagnosis, marital status, educational level and occupational status, regardless of the severity of the disease (all p>0.1). Time spent on moderate-intensity physical activity and MVPA was, however, lower in those with greater body mass index (BMI) (−6.6 min and −7 min, respectively, per BMI category increase, <25, 25–30, >30 kg/m2; p values for trend were 0.056 and 0.051, respectively). Women spent, on average, 10 min less on MVPA (p<0.001) and 22 min less on sedentary behaviours during weekends compared with weekdays (p=0.051). Conclusions These data provide an objective measure of the amount of time spent on sedentary activities and on physical activity in women with fibromyalgia. PMID:23794573

  17. The association between leisure-time physical activity and dietary fat in American adults.

    PubMed Central

    Simoes, E J; Byers, T; Coates, R J; Serdula, M K; Mokdad, A H; Heath, G W

    1995-01-01

    Relations between leisure-time physical activity and dietary fat were examined in a population-based probability sample of 29,672 adults in the 1990 Behavioral Risk Factor Surveillance System. Consumption of 13 high-fat food items and participation in physical activities were measured, and fat and activity scores were calculated. Dietary fat and physical activity were strongly and inversely associated. This association was independent of nine other demographic and behavioral risk factors. Etiologic researchers should consider that diet and physical activity can potentially confound each other, and creators of public health messages that target one behavior should consider including the other. PMID:7856785

  18. Pre & Postsynaptic Tuning of Action Potential Timing by Spontaneous GABAergic Activity

    PubMed Central

    Caillard, Olivier

    2011-01-01

    Frequency and timing of action potential discharge are key elements for coding and transfer of information between neurons. The nature and location of the synaptic contacts, the biophysical parameters of the receptor-operated channels and their kinetics of activation are major determinants of the firing behaviour of each individual neuron. Ultimately the intrinsic excitability of each neuron determines the input-output function. Here we evaluate the influence of spontaneous GABAergic synaptic activity on the timing of action potentials in Layer 2/3 pyramidal neurones in acute brain slices from the somatosensory cortex of young rats. Somatic dynamic current injection to mimic synaptic input events was employed, together with a simple computational model that reproduce subthreshold membrane properties. Besides the well-documented control of neuronal excitability, spontaneous background GABAergic activity has a major detrimental effect on spike timing. In fact, GABAA receptors tune the relationship between the excitability and fidelity of pyramidal neurons via a postsynaptic (the reversal potential for GABAA activity) and a presynaptic (the frequency of spontaneous activity) mechanism. GABAergic activity can decrease or increase the excitability of pyramidal neurones, depending on the difference between the reversal potential for GABAA receptors and the threshold for action potential. In contrast, spike time jitter can only be increased proportionally to the difference between these two membrane potentials. Changes in excitability by background GABAergic activity can therefore only be associated with deterioration of the reliability of spike timing. PMID:21789249

  19. The Developmental Pathway From Pubertal Timing to Delinquency and Sexual Activity From Early to Late Adolescence

    PubMed Central

    Negriff, Sonya; Elizabeth, J. Susman; Trickett, Penelope K.

    2013-01-01

    There is strong evidence that early pubertal timing is associated with adolescent problem behaviors. However, there has been limited investigation of the mechanisms or developmental relationships. The present study examined longitudinal models incorporating pubertal timing, delinquency, and sexual activity in a sample of 454 adolescents (9–13 years old at enrollment; 47% females). Participants were seen for three assessments approximately 1 year apart. Characteristics of friendship networks (older friends, male friends, older male friends) were examined as mediators. Structural equation modeling was used to test these associations as well as temporal relationships between sexual activity and delinquency. Results showed that early pubertal timing at Time 1 was related to more sexual activity at Time 2, which was related to higher delinquency at Time 3, a trend mediation effect. None of the friendship variables mediated these associations. Gender or maltreatment status did not moderate the meditational pathways. The results also supported the temporal sequence of sexual activity preceding increases in delinquency. These findings reveal that early maturing adolescents may actively seek out opportunities to engage in sexual activity which appears to be risk for subsequent delinquency. PMID:21191640

  20. The developmental pathway from pubertal timing to delinquency and sexual activity from early to late adolescence.

    PubMed

    Negriff, Sonya; Susman, Elizabeth J; Trickett, Penelope K

    2011-10-01

    There is strong evidence that early pubertal timing is associated with adolescent problem behaviors. However, there has been limited investigation of the mechanisms or developmental relationships. The present study examined longitudinal models incorporating pubertal timing, delinquency, and sexual activity in a sample of 454 adolescents (9-13 years old at enrollment; 47% females). Participants were seen for three assessments approximately 1 year apart. Characteristics of friendship networks (older friends, male friends, older male friends) were examined as mediators. Structural equation modeling was used to test these associations as well as temporal relationships between sexual activity and delinquency. Results showed that early pubertal timing at Time 1 was related to more sexual activity at Time 2, which was related to higher delinquency at Time 3, a trend mediation effect. None of the friendship variables mediated these associations. Gender or maltreatment status did not moderate the meditational pathways. The results also supported the temporal sequence of sexual activity preceding increases in delinquency. These findings reveal that early maturing adolescents may actively seek out opportunities to engage in sexual activity which appears to be risk for subsequent delinquency. PMID:21191640